阅读说明：本技术 一种退磁迭代控制的隔离型功率转换方法及功率转换电路 (Isolated power conversion method and power conversion circuit for demagnetization iterative control ) 是由 励晔 黄飞明 贺洁 于 2020-12-11 设计创作，主要内容包括：本发明公开了一种退磁迭代控制的隔离型功率转换方法及功率转换电路,包括高频变压器,所述高频变压器的原边与功率开关管电路中的原边功率管电连接,所述高频变压器的副边通过所述副边同步整流管分别与充电电容电路和输出反馈电路电连接,所述高频变压器的原边和副边分别与功率转换集成控制芯片电连接；本发明提出新型的退磁时间迭代环路控制架构,通过迭代运算退磁时间的长短来控制原边功率管的开关,该方法消除了反激式隔离电源右半平面零点,增加环路带宽,提升系统响应速度。还通过纹波注入方法,消除高速动态响应时信号噪声干扰的影响,采用电压自适应导通时间控制技术,省去原边电流采样电阻,降低了系统成本,并提高了系统可靠性。(The invention discloses an isolated power conversion method and a power conversion circuit for demagnetization iterative control, which comprise a high-frequency transformer, wherein the primary side of the high-frequency transformer is electrically connected with a primary power tube in a power switch tube circuit, the secondary side of the high-frequency transformer is respectively electrically connected with a charging capacitor circuit and an output feedback circuit through a secondary synchronous rectifier tube, and the primary side and the secondary side of the high-frequency transformer are respectively electrically connected with a power conversion integrated control chip; the invention provides a novel demagnetization time iterative loop control framework, which controls the switching of a primary power tube by iteratively calculating the demagnetization time, eliminates the right half-plane zero point of a flyback isolation power supply, increases the loop bandwidth, and improves the response speed of a system. And the influence of signal noise interference during high-speed dynamic response is eliminated by a ripple injection method, and a voltage self-adaptive on-time control technology is adopted, so that a primary side current sampling resistor is omitted, the system cost is reduced, and the system reliability is improved.)

1. An isolated power conversion method based on demagnetization iterative control is characterized by comprising the following steps:

firstly, a high-frequency transformer circuit of a power conversion circuit comprises a high-frequency transformer, the power-on is initial, a secondary side control circuit of the high-frequency transformer maintains a turn-off state, a primary side control circuit of the high-frequency transformer comprises an oscillator module, an alternative selector and a self-adaptive conduction time control circuit, the oscillator module in the primary side control circuit triggers the self-adaptive conduction time control circuit through the '0' input end of the alternative selector, the self-adaptive conduction time control circuit controls the conduction of a primary side power tube in a power switch tube circuit electrically connected with the self-adaptive conduction time control circuit to enable the high-frequency transformer to enter an excitation stage, and the high-frequency transformer carries out the charging of the excitation stage on a secondary side power supply capacitor in a charging capacitor circuit electrically connected with the secondary side of the high-frequency transformer through a power supply unit in the secondary side control;

step two, when the self-adaptive on-time control circuit controls the turn-off of a primary power tube in the power switch tube circuit, the high-frequency transformer enters a demagnetization stage, the high-frequency transformer charges an output capacitor in a charging capacitor circuit electrically connected to a secondary side of the high-frequency transformer in the demagnetization stage, at the moment, the secondary control circuit still maintains the turn-off of a secondary synchronous rectifier tube electrically connected to the secondary side of the high-frequency transformer, and the primary side and the secondary side of the high-frequency transformer are prevented from being opened at the same time;

after a plurality of continuous excitation stages are performed under the control of the oscillator module and the self-adaptive on-time control circuit, when the charging voltage of the secondary power supply capacitor reaches a set threshold value, the secondary control circuit sends a pulse communication signal to the primary control circuit through a high-voltage capacitor isolation circuit by using a control signal modulation circuit arranged inside the secondary control circuit so as to establish communication handshake with the primary control circuit in a demagnetization stage, and only after the handshake succeeds, the alternative selector in the primary control circuit always selects the demodulated communication signal acquired by the '1' input end to trigger the self-adaptive on-time control circuit; therefore, the secondary synchronous rectifier tube and the primary power tube controlled by the self-adaptive on-time control circuit are only controlled by the secondary control circuit to be switched on and switched off; if the primary side control circuit does not receive the communication handshake signals of the secondary side control circuit all the time, after the primary side control circuit controls a primary side power tube for dozens of switching cycles by using an oscillator module, a logic circuit with a microcontroller function arranged in the oscillator module controls the oscillator module to stop outputting signals until the primary side control circuit is automatically turned off, and the first step is repeated to restart the system;

step four, summing the feedback voltage value of the secondary side output feedback circuit of the high-frequency transformer with the output signal of the ripple injection module, comparing the obtained summed voltage value with the reference voltage value of the reference voltage circuit in the secondary side control circuit, and when the summed voltage value is smaller than the reference voltage value of the reference voltage circuit and the demagnetization time of the period is more than or equal to the demagnetization time of the previous period minus the iteration error quantity, namely Tdemⁿ≥Tdem^n-1-ΔTdem；

In the formula: tdemⁿThe demagnetization time of the nth switch; unit: microsecond;

Tdem^n-1the demagnetization time of the (n-1) th switch; unit: microsecond;

Δ Tdem iteration error amount; unit: nanosecond;

when two conditions are met, a demagnetization time iteration control unit in the secondary side control circuit firstly turns off a secondary side synchronous rectifying tube through a secondary side turn-off/turn-on unit in the secondary side control circuit, then delays for a few nanoseconds, sends a TX turn-on signal to the primary side control circuit through a control signal modulation circuit in the secondary side control circuit, the signal is coupled through a high-voltage capacitor isolation circuit and demodulated by a control signal demodulation circuit in the primary side control circuit to generate an RX signal, then the RX signal is input into a self-adaptive turn-on time control circuit in the primary side control circuit, the self-adaptive turn-on time control circuit controls the conduction of a primary side power tube, so that the high-frequency transformer obtains excitation storage energy, and simultaneously the self-adaptive turn-on time control circuit calculates the turn-on time of the primary side power tube according to a primary side bus voltage VIN parameter of the high-frequency transformer and automatically turns off the primary, the high-frequency transformer is enabled to enter a demagnetization stage and output energy to a secondary side, and a secondary side control circuit conducts a secondary side synchronous rectifying tube through a secondary side turn-off/turn-on unit arranged inside the secondary side control circuit; ensuring that a load end of a secondary side of the high-frequency transformer obtains energy supply;

and step five, detecting the feedback voltage of an output feedback circuit at the load end of the secondary side of the high-frequency transformer in real time, and repeating the step four to realize energy transfer after power conversion is carried out on the primary side of the high-frequency transformer to the secondary side of the high-frequency transformer.

2. The isolated power conversion method based on iterative demagnetization control according to claim 1,

the self-adaptive on-time control circuit comprises a voltage division circuit electrically connected with a primary side bus voltage VIN, and a first voltage control current source circuit electrically connected with the voltage division circuit, wherein the first voltage control current source circuit generates a bias current in direct proportion to the primary side bus voltage VIN, the first voltage control current source circuit is respectively and electrically connected with one end of a first capacitor, one end of a first switch and a positive input end of a second comparator, the first switch is controlled by a first single trigger circuit, the first single trigger circuit is electrically connected with a trigger output end of an alternative selector in the primary side control circuit, a negative input end of the second comparator is electrically connected with a positive electrode of a first reference voltage source, the other end of the first capacitor VIN, the other end of the first switch, a negative electrode of the first reference voltage source and a negative electrode of the primary side bus voltage are grounded, the output end of the second comparator is electrically connected with the input end of the phase inverter, and the output end of the phase inverter is electrically connected with the trigger end of the primary side power tube.

3. The isolated power conversion method based on iterative demagnetization control according to claim 2,

the self-adaptive on-time control circuit in the fourth step calculates the on-time Ton of the primary side power tube according to the primary side bus voltage VIN parameter as follows:

Ton＝C*V/(1/k*G*VIN)，

where VIN is the primary bus voltage at the primary input voltage bus of the high frequency transformer,

c is the capacitance value of the first capacitor,

v is a voltage value of the first reference voltage source,

1/k is the voltage division coefficient of the voltage division circuit,

g is a transconductance value of the first voltage controlled current source circuit.

4. The power conversion circuit of the isolated power conversion method based on demagnetization iteration control according to claim 3, characterized by comprising:

the high-frequency transformer circuit is used for voltage conversion transmission in power conversion, the high-frequency transformer circuit comprises a high-frequency transformer, the primary side of the high-frequency transformer is electrically connected with a primary side power tube in the power switch tube circuit, the secondary side of the high-frequency transformer is respectively electrically connected with a charging capacitor circuit and an output feedback circuit through a secondary side synchronous rectifier tube, the charging capacitor circuit comprises a secondary side positive output end with one end electrically connected to the excitation stage of the high-frequency transformer and a secondary side power supply capacitor with the other end electrically connected to the negative electrode of the secondary side load output end in the demagnetization stage, the high-frequency transformer circuit also comprises an output capacitor bridged on the secondary side load output end, and the output feedback circuit comprises serial RFB1 and RFB2 divider resistors bridged on the secondary side load output end; and the primary side and the secondary side of the high-frequency transformer are respectively and electrically connected with the power conversion integrated control chip.

5. The power conversion circuit of the isolated power conversion method based on iterative demagnetization control according to claim 4, wherein the power conversion integrated control chip internally comprises a primary side control circuit, a high-voltage capacitor isolation circuit and a secondary side control circuit, and the primary side control circuit is electrically connected with the power switch tube circuit; the secondary side control circuit is respectively and electrically connected with the secondary side synchronous rectifier tube, the output feedback circuit and a secondary side positive output end of the high-frequency transformer in the excitation stage; and the secondary side control circuit is communicated with the primary side control circuit through the high-voltage capacitor isolation circuit.

6. The power conversion circuit of the isolated power conversion method based on iterative demagnetization control according to claim 5, wherein the primary side control circuit internally comprises:

the oscillator module is used for providing a working pulse oscillation signal in the primary side control circuit;

the alternative selector is used for receiving the working pulse oscillation signal output by the oscillator module and receiving the communication signal transmitted by the high-voltage capacitive isolation circuit;

the D trigger is used for receiving the communication signal transmitted by the high-voltage capacitor isolation circuit and outputting a trigger result to the control end of the alternative selector from the output end;

the self-adaptive on-time control circuit is used for receiving an output signal of the output end of the alternative selector and controlling the on-time and the off-time of a primary side power tube in the power switch tube circuit by combining the primary side bus voltage VIN of the high-frequency transformer;

the oscillator module is electrically connected with an input end of an alternative selector '0', an input end of an alternative selector '1' is electrically connected with an output end of a control signal demodulation circuit, a Q output end of the D trigger is electrically connected with a control end of the alternative selector, a D input end of the D trigger is electrically connected with a high level, and a time sequence CLK input end of the D trigger is electrically connected with the high-voltage capacitor isolation circuit through the control signal demodulation circuit; the output end of the alternative selector is electrically connected with the self-adaptive on-time control circuit included in the primary side control circuit.

7. The power conversion circuit of the isolated power conversion method based on demagnetization iterative control according to claim 6, wherein the secondary side control circuit includes therein:

the power supply unit is electrically connected with a secondary positive output end of the high-frequency transformer in an excitation stage to obtain electric energy so as to charge a secondary power supply capacitor in the charging capacitor circuit;

the ripple injection module is used for providing a ripple signal required by summation with a feedback voltage value of the output feedback circuit;

the adder is used for summing the ripple signal and the feedback voltage value of the output feedback circuit;

the demagnetization time iteration control unit is used for realizing the communication handshake control and the demagnetization time iteration control between the secondary side control circuit and the primary side control circuit through the high-voltage capacitor isolation circuit;

the secondary side turn-off/turn-on unit is used for controlling the turn-off/turn-on of the secondary side synchronous rectifier tube and the demagnetization time iteration control unit;

a reference voltage circuit providing a reference voltage value compared with a result of summing between the ripple signal and a feedback voltage value of the output feedback circuit;

a first comparator for comparing a result of summing between the ripple signal and a feedback voltage value of the output feedback circuit with a reference voltage value of the reference voltage circuit in magnitude;

and the control signal modulation circuit is used for modulating the communication handshake signals output by the demagnetization time iteration control unit.

8. The power conversion circuit according to claim 7, wherein the demagnetization time iterative control unit comprises a second switch having a control terminal electrically connected to the output terminal of the secondary side turn-off/turn-on unit, and a third switch having a control terminal electrically connected to the output terminal of the secondary side turn-off/turn-on unit through a pulse trigger circuit, wherein a first base of the second switch is electrically connected to the second voltage-controlled current source circuit, a second base of the second switch is electrically connected to a first base of the third switch and a positive input terminal of a third comparator TB, a second base of the third switch is grounded to a negative terminal of the secondary side of the high frequency transformer during the demagnetization period, and a second base of the second switch is electrically connected to a first base of a fourth switch and one end of a second capacitor, the second base electrode of the fourth switch is electrically connected with one end of the third capacitor, the second base electrode of the fourth switch is also electrically connected with the negative electrode of the positive iteration error amount voltage source and the positive electrode of the negative iteration error amount voltage source respectively, the positive pole of the positive iteration error voltage source is electrically connected with the negative input end of the third comparator TB through a fifth switch and the negative pole of the negative iteration error voltage source is electrically connected with the negative input end of the third comparator TB through a sixth switch, the output end of the third comparator TB is electrically connected with the D input end of a second D trigger, the Q output end of the second D trigger is electrically connected with the control end of the fifth switch, the Q non-output end of the second D trigger is electrically connected with the control end of the sixth switch, the control end of the fourth switch and the CP input end of the second D trigger are electrically connected with the ONTRIG output end of the first comparator, and the output end of the third comparator TB is also electrically connected with the control signal modulation circuit.

9. The power conversion circuit of the isolated power conversion method based on iterative demagnetization control according to claim 8,

the ripple injection module comprises a seventh switch, a control end of the seventh switch is electrically connected with an ONTRIG output end of the first comparator through a second single trigger circuit, a first base of the seventh switch is electrically connected with one end of a second reference voltage source, a second base of the seventh switch is electrically connected with one end of a fourth capacitor and one end of a first resistor, a second base of the seventh switch is further electrically connected with the adder, and the other ends of the second reference voltage source, the fourth capacitor and the first resistor are grounded with a secondary cathode of the high-frequency transformer in a demagnetization stage.

Technical Field

The invention belongs to the field of integrated circuits related to power conversion control circuits, relates to a switching power supply control technology, and particularly relates to an isolated power conversion method and a power conversion circuit for demagnetization iterative control.

Background

With the rapid development of 5G communication, Internet of things, smart home and the like, the shipment volume of electronic products such as mobile phones, PADs, small household appliances, network equipment and the like is increased dramatically, and the related power chips are driven to grow rapidly year by year.

The isolation type power converter realizes energy transfer in a high-frequency transformer electromagnetic conversion mode, and the electrical isolation characteristic of the isolation type power converter avoids the harm of a high-voltage input domain to low-voltage equipment or a human body, so that the isolation type power converter is widely applied to a power supply system of electronic equipment. The flyback isolated power supply is the mainstream application of the medium and small power section isolated power supply due to the simple application structure and low cost. The feedback control signal of the flyback isolation power supply is generally transmitted by devices such as a main high-frequency transformer or an optical coupler, the system response of the flyback isolation power supply lags behind one switching period by adopting the control signal transmitted by the main high-frequency transformer, and the system response is influenced by the slow transmission speed of the control signal transmitted by the optical coupler. In addition, the flyback isolated power supply with the conventional architecture has a right half-plane zero point, and the problem of system stability is often solved by reducing the loop bandwidth in application, so that the loop dynamic response speed is low.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides an isolated power conversion method and a power conversion circuit for demagnetization iteration control.

In order to achieve the above object, the present invention provides an isolated power conversion method for demagnetization iterative control, comprising the steps of:

firstly, a high-frequency transformer circuit of a power conversion circuit comprises a high-frequency transformer, the power-on is initial, a secondary side control circuit of the high-frequency transformer maintains a turn-off state, a primary side control circuit of the high-frequency transformer comprises an oscillator module, an alternative selector and a self-adaptive conduction time control circuit, the oscillator module in the primary side control circuit triggers the self-adaptive conduction time control circuit through the '0' input end of the alternative selector, the self-adaptive conduction time control circuit controls the conduction of a primary side power tube in a power switch tube circuit electrically connected with the self-adaptive conduction time control circuit to enable the high-frequency transformer to enter an excitation stage, and the high-frequency transformer carries out the charging of the excitation stage on a secondary side power supply capacitor in a charging capacitor circuit electrically connected with the secondary side of the high-frequency transformer through a power supply unit in the secondary side control;

step two, when the self-adaptive on-time control circuit controls the turn-off of a primary power tube in the power switch tube circuit, the high-frequency transformer enters a demagnetization stage, the high-frequency transformer charges an output capacitor in a charging capacitor circuit electrically connected to a secondary side of the high-frequency transformer in the demagnetization stage, at the moment, the secondary control circuit still maintains the turn-off of a secondary synchronous rectifier tube electrically connected to the secondary side of the high-frequency transformer, and the primary side and the secondary side of the high-frequency transformer are prevented from being opened at the same time;

after a plurality of continuous excitation stages are performed under the control of the oscillator module and the self-adaptive on-time control circuit, when the charging voltage of the secondary power supply capacitor reaches a set threshold value, the secondary control circuit sends a pulse communication signal to the primary control circuit through a high-voltage capacitor isolation circuit by using a control signal modulation circuit arranged inside the secondary control circuit so as to establish communication handshake with the primary control circuit in a demagnetization stage, and only after the handshake succeeds, the alternative selector in the primary control circuit always selects the demodulated communication signal acquired by the '1' input end to trigger the self-adaptive on-time control circuit; therefore, the secondary synchronous rectifier tube and the primary power tube controlled by the self-adaptive on-time control circuit are only controlled by the secondary control circuit to be switched on and switched off; if the primary side control circuit does not receive the communication handshake signals of the secondary side control circuit all the time, after the primary side control circuit controls a primary side power tube for dozens of switching cycles by using an oscillator module, a logic circuit with a microcontroller function arranged in the oscillator module controls the oscillator module to stop outputting signals until the primary side control circuit is automatically turned off, and the first step is repeated to restart the system;

step four, the feedback voltage value of the output feedback circuit of the secondary side of the high-frequency transformer is summed with the output signal of the ripple injection module, the obtained summed voltage value is compared with the reference voltage value of the reference voltage circuit in the secondary side control circuit,when the summation voltage value is less than the reference voltage value of the reference voltage circuit and the demagnetization time of the period is more than or equal to the demagnetization time of the previous period minus the iteration error amount, namely Tdemⁿ≥Tdem^n-1-ΔTdem；

In the formula: tdemⁿThe demagnetization time of the nth switch; unit: microsecond;

Tdem^n-1the demagnetization time of the (n-1) th switch; unit: microsecond;

Δ Tdem iteration error amount; unit: nanosecond;

when two conditions are met, a demagnetization time iteration control unit in the secondary side control circuit firstly turns off a secondary side synchronous rectifying tube through a secondary side turn-off/turn-on unit in the secondary side control circuit, then delays for a few nanoseconds, sends a TX turn-on signal to the primary side control circuit through a control signal modulation circuit in the secondary side control circuit, the signal is coupled through a high-voltage capacitor isolation circuit and demodulated by a control signal demodulation circuit in the primary side control circuit to generate an RX signal, then the RX signal is input into a self-adaptive turn-on time control circuit in the primary side control circuit, the self-adaptive turn-on time control circuit controls the conduction of a primary side power tube, so that the high-frequency transformer obtains excitation storage energy, and simultaneously the self-adaptive turn-on time control circuit calculates the turn-on time of the primary side power tube according to a primary side bus voltage VIN parameter of the high-frequency transformer and automatically turns off the primary, the high-frequency transformer is enabled to enter a demagnetization stage and output energy to a secondary side, and a secondary side control circuit conducts a secondary side synchronous rectifying tube through a secondary side turn-off/turn-on unit arranged inside the secondary side control circuit; ensuring that a load end of a secondary side of the high-frequency transformer obtains energy supply;

and step five, detecting the feedback voltage of an output feedback circuit at the load end of the secondary side of the high-frequency transformer in real time, and repeating the step four to realize energy transfer after power conversion is carried out on the primary side of the high-frequency transformer to the secondary side of the high-frequency transformer.

In addition, the embodiment according to the present invention may also have the following additional technical features:

the self-adaptive on-time control circuit comprises a voltage division circuit electrically connected with a primary side bus voltage VIN, and a first voltage control current source circuit electrically connected with the voltage division circuit, wherein the first voltage control current source circuit generates a bias current in direct proportion to the primary side bus voltage VIN, the first voltage control current source circuit is respectively and electrically connected with one end of a first capacitor, one end of a first switch and a positive input end of a second comparator, the first switch is controlled by a first single trigger circuit, the first single trigger circuit is electrically connected with a trigger output end of an alternative selector in the primary side control circuit, a negative input end of the second comparator is electrically connected with a positive electrode of a first reference voltage source, the other end of the first capacitor VIN, the other end of the first switch, a negative electrode of the first reference voltage source and a negative electrode of the primary side bus voltage are grounded, the output end of the second comparator is electrically connected with the input end of the phase inverter, and the output end of the phase inverter is electrically connected with the trigger end of the primary side power tube.

The self-adaptive on-time control circuit in the fourth step calculates the on-time Ton of the primary side power tube according to the primary side bus voltage VIN parameter as follows:

Ton＝C*V/(1/k*G*VIN)，

where VIN is the primary bus voltage at the primary input voltage bus of the high frequency transformer,

c is the capacitance value of the first capacitor,

v is a voltage value of the first reference voltage source,

1/k is the voltage division coefficient of the voltage division circuit,

g is a transconductance value of the first voltage controlled current source circuit.

A power conversion circuit of an isolated power conversion method based on demagnetization iteration control comprises the following steps:

the high-frequency transformer circuit is used for voltage conversion transmission in power conversion, the high-frequency transformer circuit comprises a high-frequency transformer, the primary side of the high-frequency transformer is electrically connected with a primary side power tube in the power switch tube circuit, the secondary side of the high-frequency transformer is respectively electrically connected with a charging capacitor circuit and an output feedback circuit through a secondary side synchronous rectifier tube, the charging capacitor circuit comprises a secondary side positive output end with one end electrically connected to the excitation stage of the high-frequency transformer and a secondary side power supply capacitor with the other end electrically connected to the negative electrode of the secondary side load output end in the demagnetization stage, the high-frequency transformer circuit also comprises an output capacitor bridged on the secondary side load output end, and the output feedback circuit comprises serial RFB1 and RFB2 divider resistors bridged on the secondary side load output end; and the primary side and the secondary side of the high-frequency transformer are respectively and electrically connected with the power conversion integrated control chip.

The power conversion integrated control chip internally comprises a primary side control circuit, a high-voltage capacitor isolation circuit and a secondary side control circuit, wherein the primary side control circuit is electrically connected with the power switch tube circuit; the secondary side control circuit is respectively and electrically connected with the secondary side synchronous rectifier tube, the output feedback circuit and a secondary side positive output end of the high-frequency transformer in the excitation stage; and the secondary side control circuit is communicated with the primary side control circuit through the high-voltage capacitor isolation circuit.

The primary side control circuit comprises:

the oscillator module is used for providing a working pulse oscillation signal in the primary side control circuit;

the alternative selector is used for receiving the working pulse oscillation signal output by the oscillator module and receiving the communication signal transmitted by the high-voltage capacitive isolation circuit;

the D trigger is used for receiving the communication signal transmitted by the high-voltage capacitor isolation circuit and outputting a trigger result to the control end of the alternative selector from the output end;

the self-adaptive on-time control circuit is used for receiving an output signal of the output end of the alternative selector and controlling the on-time and the off-time of a primary side power tube in the power switch tube circuit by combining the primary side bus voltage VIN of the high-frequency transformer;

the oscillator module is electrically connected with an input end of an alternative selector '0', an input end of an alternative selector '1' is electrically connected with an output end of a control signal demodulation circuit, a Q output end of the D trigger is electrically connected with a control end of the alternative selector, a D input end of the D trigger is electrically connected with a high level, and a time sequence CLK input end of the D trigger is electrically connected with the high-voltage capacitor isolation circuit through the control signal demodulation circuit; the output end of the alternative selector is electrically connected with the self-adaptive on-time control circuit included in the primary side control circuit.

The inside of secondary limit control circuit is including being equipped with:

the power supply unit is electrically connected with a secondary positive output end of the high-frequency transformer in an excitation stage to obtain electric energy so as to charge a secondary power supply capacitor in the charging capacitor circuit;

the ripple injection module is used for providing a ripple signal required by summation with a feedback voltage value of the output feedback circuit;

the adder is used for summing the ripple signal and the feedback voltage value of the output feedback circuit;

the demagnetization time iteration control unit is used for realizing the communication handshake control and the demagnetization time iteration control between the secondary side control circuit and the primary side control circuit through the high-voltage capacitor isolation circuit;

the secondary side turn-off/turn-on unit is used for controlling the turn-off/turn-on of the secondary side synchronous rectifier tube and the demagnetization time iteration control unit;

a reference voltage circuit providing a reference voltage value compared with a result of summing between the ripple signal and a feedback voltage value of the output feedback circuit;

a first comparator for comparing a result of summing between the ripple signal and a feedback voltage value of the output feedback circuit with a reference voltage value of the reference voltage circuit in magnitude;

and the control signal modulation circuit is used for modulating the communication handshake signals output by the demagnetization time iteration control unit.

The demagnetization time iteration control unit comprises a control end, a second switch and a control end, wherein the second switch and the control end are electrically connected with the output end of the secondary side turn-off/turn-on unit through a pulse trigger circuit, the third switch is electrically connected with the output end of the secondary side turn-off/turn-on unit, a first base of the second switch is electrically connected with a second voltage control current source circuit, a second base of the second switch is electrically connected with a first base of the third switch and a positive input end of a third comparator TB, a second base of the third switch is electrically connected with a secondary side cathode of a demagnetization stage of the high-frequency transformer, a second base of the second switch is electrically connected with a first base of a fourth switch and one end of a second capacitor, a second base of the fourth switch is electrically connected with one end of a third capacitor, and a second base of the fourth switch is electrically connected with a positive electrode of a positive iteration error amount voltage source and a negative iteration error amount voltage source respectively, the positive electrode of the positive iteration error voltage source is electrically connected with the negative input end of a third comparator TB through a fifth switch and the negative iteration error voltage source is electrically connected with the D input end of a second D trigger through a sixth switch, the Q output end of the second D trigger is electrically connected with the control end of the fifth switch, the Q non-output end of the second D trigger is electrically connected with the control end of the sixth switch, the control end of the fourth switch and the CP input end of the second D trigger are electrically connected with the ONTRIG output end of the first comparator, and the output end of the third comparator TB is also electrically connected with a control signal modulation circuit.

The ripple injection module comprises a seventh switch, a control end of the seventh switch is electrically connected with an ONTRIG output end of the first comparator through a second single trigger circuit, a first base of the seventh switch is electrically connected with one end of a second reference voltage source, a second base of the seventh switch is electrically connected with one end of a fourth capacitor and one end of a first resistor, a second base of the seventh switch is further electrically connected with the adder, and the other ends of the second reference voltage source, the fourth capacitor and the first resistor are grounded with a secondary cathode of the high-frequency transformer in a demagnetization stage.

The invention provides an isolated power conversion method and circuit with high-speed dynamic response demagnetization iterative control, which are characterized in that a control signal generated by a secondary side is transmitted to a primary side in real time to control the switching of a primary side power tube through high-voltage isolation signal coupling, so that the signal transmission delay time is reduced. In addition, the invention also provides a novel demagnetization time iterative loop control framework, the switching of the primary power tube is controlled by iteratively calculating the demagnetization time, the method eliminates the right half-plane zero point of the flyback isolation power supply, increases the loop bandwidth and improves the response speed of the system. In addition, the invention also eliminates the influence of signal noise interference during high-speed dynamic response by a ripple injection method, and improves the stability of the system. The invention combines a demagnetization time iterative loop control framework, adopts a voltage self-adaptive conduction time control technology, saves a primary current sampling resistor, reduces the system cost and improves the system reliability.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments taken in conjunction with the accompanying drawings,

FIG. 1 is a schematic diagram of the power conversion circuitry control circuitry of the present invention;

FIG. 2 is a control circuit loop control schematic of the power conversion circuitry of the present invention;

FIG. 3 is a schematic diagram of the demagnetization time iterative control principle of the present invention;

FIG. 4 is a schematic diagram of the ripple injection signal waveform of the present invention;

FIG. 5 is a schematic diagram of an adaptive on-time control circuit according to the present invention;

FIG. 6 is a schematic diagram of the principle of the demagnetization time iterative control unit of the invention;

FIG. 7 is a schematic diagram of the ripple injection module of the present invention;

101-an input voltage bus, 102-a high-frequency transformer, 103-a primary power tube, 104-a secondary synchronous rectifier tube, 105-an output capacitor, 106-a secondary power supply capacitor, 107-an output feedback circuit, 110-a primary control circuit, 111-an alternative selector, 112-an oscillator module, 113-D flip-flop, 114-a control signal demodulation circuit, 115-an adaptive on-time control circuit, 120-a secondary control circuit, 121-a control signal modulation circuit, 122-a high level node, 123-a secondary off/on unit, 124-a demagnetization time iteration control unit, 125-a ripple injection module, 126-a power supply unit, 127-a first comparator, 128-an adder and 129-a reference voltage circuit, 130-high voltage capacitor isolation circuit, 501-voltage division circuit, 502-first voltage control current source circuit, 503-first one-time trigger circuit, 505-first switch, 506-first capacitor, 507-first reference voltage source, 508-second comparator, 509-inverter.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention. The following is further explained with reference to the drawings;

in fig. 1 to 7, an isolated power conversion method based on demagnetization iterative control is provided, which includes the steps of:

step one, the high frequency transformer circuit of the power conversion circuit comprises a high frequency transformer 102, and the power is initially electrified, the secondary control circuit 120 of the high frequency transformer 102 maintains an off state, the primary control circuit 110 of the high frequency transformer 102 includes an oscillator module 112, an alternative selector 111, and an adaptive on-time control circuit 115, the oscillator module 112 in the primary side control circuit 110 triggers the adaptive on-time control circuit 115 through the input of the alternative selector 111 '0', the adaptive on-time control circuit 115 controls the on-state of the primary power tube 103 in the power switching tube circuit electrically connected to the adaptive on-time control circuit, so that the high-frequency transformer 102 enters an excitation stage, the high frequency transformer 102 charges the secondary power supply capacitor 106 in the secondary charging capacitor circuit electrically connected to the secondary side of the high frequency transformer through the power supply unit 126 in the secondary control circuit 120;

step two, when the adaptive on-time control circuit 115 controls the turn-off of the primary power tube 103 in the power switch tube circuit, the high-frequency transformer 102 enters a demagnetization stage, the high-frequency transformer 102 charges the output capacitor 105 in the charging capacitor circuit electrically connected to the secondary side of the high-frequency transformer 102 in the demagnetization stage, at this time, the secondary control circuit 120 still maintains the turn-off of the secondary synchronous rectifier tube 104 electrically connected to the secondary side of the high-frequency transformer 102, and the primary side and the secondary side of the high-frequency transformer 102 are prevented from being simultaneously opened;

step three, after a plurality of consecutive excitation stages under the control of the oscillator module 112 and the adaptive on-time control circuit 115, when the charging voltage of the secondary power supply capacitor 106 reaches a set threshold value, the secondary control circuit 120 sends a pulse communication signal to the primary control circuit 110 through the high-voltage capacitor isolation circuit 130 by using the control signal modulation circuit 121 arranged inside, so as to establish a communication handshake with the primary control circuit 110 at a demagnetization stage, and only after the handshake succeeds, the alternative selector 111 in the primary control circuit 110 always selects the demodulated communication signal obtained at the '1' input end to trigger the adaptive on-time control circuit 115; therefore, the secondary synchronous rectifier 104 and the primary power tube 103 controlled by the adaptive on-time control circuit 115 are both turned on and off only by the secondary control circuit 120; if the primary side control circuit 110 does not receive the communication handshake signal of the secondary side control circuit 120 all the time, after the primary side control circuit 110 controls the primary side power tube 103 by using the oscillator module 112 for tens of switching cycles, the oscillator module 112 is controlled by a logic circuit with a microcontroller function arranged in the oscillator module 112 to stop outputting signals until the primary side control circuit 110 is automatically turned off, and the first step is repeated to restart the system;

step four, summing the feedback voltage value of the secondary side output feedback circuit 107 of the high-frequency transformer 102 with the output signal of the ripple injection module 125, comparing the obtained summed voltage value with the reference voltage value of the reference voltage circuit in the secondary side control circuit 120, and when the summed voltage value is smaller than the reference voltage value of the reference voltage circuit and the demagnetization time of the period is greater than or equal to the demagnetization time of the previous period minus the iteration error, namely Tdemⁿ≥Tdem^n-1-ΔTdem；

In the formula: tdemⁿThe demagnetization time of the nth switch; unit: microsecond;

Tdem^n-1the demagnetization time of the (n-1) th switch; unit: microsecond;

Δ Tdem iteration error amount; unit: nanosecond;

when the two conditions are met, the demagnetization time iterative control unit 124 in the secondary control circuit 120 firstly turns off the secondary synchronous rectifier 104 through the secondary turn-off/turn-on unit 123 in the secondary control circuit 120, and then delays for several nanoseconds, sends a TX on signal to the primary control circuit 110 through the control signal modulation circuit 121 in the secondary control circuit 120, the TX on signal is coupled through the high-voltage capacitance isolation circuit 130, and is demodulated by the control signal demodulation circuit 114 in the primary control circuit 110 to generate an RX signal, and then the RX signal is input to the adaptive on-time control circuit 115 in the primary control circuit 110, and controls the primary power tube 103 to be on, so that the high-frequency transformer 102 obtains excitation VIN stored energy, and the adaptive on-time control circuit 115 calculates the on-time of the primary power tube 103 according to the primary bus voltage parameter of the high-frequency transformer 102, after the time is finished, the primary power tube 103 is automatically turned off, so that the high-frequency transformer 102 enters a demagnetization stage and outputs energy to the secondary side, and the secondary side control circuit 120 turns on the secondary side synchronous rectifier tube 104 through a secondary side turn-off/turn-on unit 123 included inside; ensuring that the load end of the secondary side of the high-frequency transformer 102 obtains energy supply;

and step five, detecting the feedback voltage of the output feedback circuit 107 at the load end of the secondary side of the high-frequency transformer 102 in real time, and repeating the step four to realize energy transfer after power conversion is carried out on the primary side of the high-frequency transformer 102 to the secondary side of the high-frequency transformer 102.

The adaptive on-time control circuit 115 includes a voltage dividing circuit 501 electrically connected to a primary side bus voltage VIN, and a first voltage control current source circuit 502 electrically connected to the voltage dividing circuit 501, where the first voltage control current source circuit 502 generates a bias current proportional to the primary side bus voltage VIN, the first voltage control current source circuit 502 is electrically connected to one end of a first capacitor 506, one end of a first switch 505, and a positive input terminal of a second comparator 508, the first switch 505 is controlled by a first one-time trigger circuit 503, the first one-time trigger circuit 503 is electrically connected to a trigger output terminal of the two-select selector 111 in the primary side control circuit 110, a negative input terminal of the second comparator is electrically connected to a positive electrode of a first reference voltage source 507, another end of the first capacitor 506, another end of the first switch 505, a negative electrode of the first reference voltage source 507 is common to the negative electrode of the primary side bus voltage VIN, the output end of the second comparator 508 is electrically connected to the input end of an inverter 509, and the output end of the inverter 509 is electrically connected to the trigger end of the primary power tube 103.

The self-adaptive on-time control circuit 115 in the fourth step calculates the on-time Ton of the primary side power tube 103 according to the primary side bus voltage VIN parameter as follows:

Ton＝C*V/(1/k*G*VIN)，

where VIN is the primary bus voltage on the primary input voltage bus 101 of the high frequency transformer,

c is the capacitance value of the first capacitor 506,

v is the voltage value of the first reference voltage source 507,

1/k is the voltage division coefficient of the voltage division circuit 501,

g is the transconductance value of the first voltage controlled current source circuit 502.

A power conversion circuit of an isolated power conversion method based on demagnetization iteration control comprises the following steps:

the high-frequency transformer circuit is used for voltage conversion transmission in power conversion, the high-frequency transformer circuit comprises a high-frequency transformer 102, the primary side of the high-frequency transformer 102 is electrically connected with a primary power tube 103 in the power switch tube circuit, the secondary side of the high-frequency transformer 102 is respectively electrically connected with a charging capacitor circuit and an output feedback circuit 107 through a secondary synchronous rectifier tube 104, the charging capacitor circuit comprises a secondary power supply capacitor 106, one end of the secondary power supply capacitor 106 is electrically connected with the positive output end of the secondary side of the high-frequency transformer 102 in the excitation stage, the other end of the secondary power supply capacitor 106 is electrically connected with the negative electrode of the secondary load output end in the demagnetization stage, the charging capacitor circuit also comprises an output capacitor 105, the output feedback circuit 107 comprises serial RFB1 and RFB2 divider resistors, and the serial RFB 89; the primary side and the secondary side of the high-frequency transformer 102 are respectively and electrically connected with the power conversion integrated control chip.

The power conversion integrated control chip internally comprises a primary side control circuit 110, a high-voltage capacitance isolation circuit 130 and a secondary side control circuit 120, wherein the primary side control circuit 110 is electrically connected with the power switch tube circuit; the secondary control circuit 120 is electrically connected to the secondary synchronous rectifier 104, the output feedback circuit 107, and a secondary positive output terminal of the high-frequency transformer 102 at the excitation stage, respectively; the secondary control circuit 120 communicates with the primary control circuit 110 via the high-voltage capacitive isolation circuit 130.

The primary side control circuit 110 includes:

an oscillator module 112, configured to provide a working pulse oscillation signal in the primary side control circuit 110;

the alternative selector 111 is configured to receive the working pulse oscillation signal output by the oscillator module 112 and receive the communication signal transmitted by the high-voltage capacitive isolation circuit 130;

the D flip-flop 113 is configured to receive the communication signal transmitted by the high-voltage capacitive isolation circuit 130, and output a trigger result to the control end of the one-of-two selector 111 through an output end;

the self-adaptive on-time control circuit is used for receiving an output signal of the output end of the alternative selector and controlling the on-time and the off-time of a primary side power tube in the power switch tube circuit by combining the primary side bus voltage VIN of the high-frequency transformer;

the oscillator module 112 is electrically connected to an input end of the one-of-two selector 111 '0', an input end of the one-of-two selector 111 '1' is electrically connected to an output end of the control signal demodulation circuit 121, a Q output end of the D flip-flop 113 is electrically connected to a control end of the one-of-two selector 111, a D input end of the D flip-flop 113 is electrically connected to a high level, and a timing CLK input end of the D flip-flop 113 is electrically connected to the high voltage capacitor isolation circuit 130 through the control signal demodulation circuit 121; the output terminal of the alternative selector 111 is electrically connected to the adaptive on-time control circuit 115 included in the primary side control circuit 110.

The secondary control circuit 120 includes:

the power supply unit 126 is electrically connected with the positive secondary output end of the high-frequency transformer 102 in the excitation stage to obtain electric energy, so as to charge the secondary power supply capacitor 106 in the charging capacitor circuit;

a ripple injection module 125 for providing a ripple signal required for summing with the feedback voltage value of the output feedback circuit 107;

an adder 128 for performing summation between the ripple signal and the feedback voltage value of the output feedback circuit 107;

a demagnetization time iterative control unit 124, configured to implement handshake control and demagnetization time iterative control between the secondary control circuit 120 and the primary control circuit 110 through communication between the high-voltage capacitor isolation circuit 130;

a secondary side turn-off/turn-on unit 123, configured to control turn-off/turn-on of the secondary side synchronous rectifier 104 and the demagnetization time iteration control unit 124;

a reference voltage circuit 129 that provides a reference voltage value that is compared with the result of summing between the ripple signal and the feedback voltage value of the output feedback circuit 107;

a first comparator 127 for comparing the magnitude of the result of the summation between the ripple signal and the feedback voltage value of the output feedback circuit 107 with the reference voltage value of the reference voltage circuit 129;

and the control signal modulation circuit 121 is configured to modulate the communication handshake signal output by the demagnetization time iteration control unit 124.

The demagnetization time iteration control unit 124 comprises a second switch and a third switch, wherein the second switch is electrically connected with the output end of the secondary side turn-off/turn-on unit 123 at the control end, the second switch is electrically connected with the output end of the secondary side turn-off/turn-on unit 123 at the control end through a pulse trigger circuit, the first base of the second switch is electrically connected with the second voltage control current source circuit, the second base of the second switch is electrically connected with the first base of the third switch and the positive input end of the third comparator TB, the second base of the third switch is grounded with the negative side of the demagnetization stage of the high-frequency transformer, the second base of the second switch is electrically connected with the first base of the fourth switch and one end of the second capacitor, the second base of the fourth switch is electrically connected with one end of the third capacitor, and the second base of the fourth switch is electrically connected with the negative electrode of the forward iteration quantity voltage source and the positive electrode of the iteration negative iteration error quantity voltage source respectively, the positive electrode of the positive iteration error voltage source is electrically connected with the negative input end of a third comparator TB through a fifth switch and the negative electrode of the negative iteration error voltage source is electrically connected with the D input end of a second D flip-flop through a sixth switch, the Q output end of the second D flip-flop is electrically connected with the control end of the fifth switch, the Q non-output end of the second D flip-flop is electrically connected with the control end of the sixth switch, the control end of the fourth switch and the CP input end of the second D flip-flop are electrically connected with the ONTRIG output end of the first comparator 127, and the output end of the third comparator TB is further electrically connected with the control signal modulation circuit 121.

The ripple injection module 125 includes a seventh switch having a control end electrically connected to the ONTRIG output end of the first comparator 127 through a second single trigger circuit, a first base of the seventh switch is electrically connected to one end of the second reference voltage source, a second base of the seventh switch is electrically connected to one end of the fourth capacitor and one end of the first resistor, a second base of the seventh switch is further electrically connected to the adder 128, and the other end of the second reference voltage source, the fourth capacitor and the first resistor is grounded to the negative pole of the secondary side of the demagnetization stage of the high-frequency transformer 102.

Fig. 1 is a block diagram of a control circuit of a power conversion system according to the present invention. The high-frequency transformer comprises a high-frequency transformer 102T 1, a primary power tube 103NP, a secondary synchronous rectifier tube 104NS, a secondary power supply capacitor 106 CSS, an output capacitor 105 COUT, output voltage-dividing resistors RFB1 and RFB2 in an output feedback circuit 107, a primary control circuit 110, a secondary control circuit 120 and a high-voltage capacitor isolation circuit 130.

Wherein the primary side control circuit 110 includes: the system comprises an alternative selector 111, an oscillator module 112, a D trigger 113, a control signal demodulation circuit 114 and an adaptive on-time control circuit 115.

Wherein the secondary control circuit 120 includes: the circuit comprises a control signal modulation circuit 121, a high-level node 122, a secondary side turn-off/turn-on unit 123, a demagnetization time iteration control circuit 124, a ripple injection module 125, a power supply unit 126, a first comparator 127, an adder circuit 128 and a reference voltage circuit 129.

Here, the primary side control circuit 110, the secondary side control circuit 120 and the high voltage capacitive isolation circuit 130 may be integrated in one chip.

Here, the high voltage capacitive isolation circuit 130 includes a high voltage isolation capacitor, or a signal isolation circuit such as a high frequency isolation coil. The primary side control circuit is used for realizing electrical isolation between the primary side control circuit and the secondary side control circuit, and meanwhile, a communication link is realized between the primary side control circuit and the secondary side control circuit.

Before the system is powered on, the voltage of the secondary supply capacitor 106 CSS is zero, the voltage of the output capacitor 105 COUT is zero, and the primary side control circuit 110 and the secondary side control circuit 120 are both kept in an off state.

At the initial power-on of the system, the output end Q of the D flip-flop 113 is initialized to low level, and the signal of the '0' input end of the standard logic unit alternative selector 111 is gated. The initial output of the oscillator module 112 is at a low level, the initial value of the output end ONP of the adaptive on-time control circuit 115 is at a low level, and the primary power tube 103NP is kept in an off state. Thereafter, the oscillator module 112 in the primary side control circuit 110 starts to operate, and the pulse signal output by the oscillator module passes through the alternative selector 111, and then triggers the adaptive on-time control circuit 115 to output a positive level pulse signal ONP, where the positive level pulse width of the ONP is inversely proportional to the primary side bus voltage VIN. In the stage that the ONP signal is a positive level pulse, the primary power tube 103NP is turned on, and enters an excitation process with the input voltage bus 101 and the high frequency transformer 102T 1.

During the excitation, the dotted terminal of the high frequency transformer 102T 1 is at a low level, the dotted terminal is at a high level, and the high level node 122 corresponds thereto. That is, drain signal VD of secondary synchronous rectifier 104NS is at a high level, and this high level charges secondary power supply capacitor CSS through power supply section 126. Here, power supply unit 126 is a unidirectional dc current source, and when the voltage at high-level node 122 VD is greater than the voltage across secondary power supply capacitor 106 CSS, power supply unit 126 charges secondary power supply capacitor 106 CSS, and when the VD voltage is less than the voltage across secondary power supply capacitor 106 CSS, power supply unit 126 disconnects the charging path to secondary power supply capacitor 106 CSS, and neither charges nor discharges.

When the positive level pulse of the ONP signal is turned to a low level, the primary power tube 103NP is turned off, the homonymous terminal of the high-frequency transformer 102T 1 becomes a high level, and the synonym terminal is a low level relative to the homonymous terminal, the high-frequency transformer 102 enters a demagnetization stage, and the energy in the high-frequency transformer 102 charges the output capacitor COUT through the body diode of the secondary synchronous rectifier 104NS, so that the output voltage rises. At this time, the secondary synchronous rectifier 104NS is kept off, and the primary side and the secondary side of the high-frequency transformer 102 are prevented from being simultaneously opened.

The output frequency of the oscillator module 112 may be set slightly greater than 20KHz, avoiding the audio range.

The switches of the entire conversion circuitry are controlled by the oscillator module 112 before the control signal demodulation circuit 114 receives the signal.

In one switching cycle, secondary supply capacitor 106 CSS can only be charged when high-frequency transformer 102T 1 is excited, and the amount of charge depends on the magnitude of the current source of power supply unit 126 and the excitation time of high-frequency transformer 102T 1.

After a plurality of switching cycles, the voltage of the secondary supply capacitor 106 CSS gradually increases, and when the voltage of the secondary supply capacitor 106 CSS reaches a set threshold, the secondary prepares to send a handshake signal, and establishes communication with the primary side after passing through the control signal modulation circuit 121, the high-voltage capacitor isolation circuit 130, and the control signal demodulation circuit 114.

The communication handshake process occurs during the demagnetization phase of high frequency transformer 102.

In the communication handshake process, the secondary side sends out a pulse signal TX, which is modulated by the control signal modulation circuit 121, coupled by the high-voltage capacitive isolation circuit 130, and demodulated by the control signal demodulation circuit 114 to generate an RX signal, which is respectively connected to the clock input terminal of the D flip-flop 113 and the one-out-of-two selector 111. The input terminal of the D flip-flop 113 starts to terminate high, and after the input terminal is triggered by the RX signal and the output terminal becomes high, the either-or selector 111 is controlled to always select the RX signal at the '1' input terminal. After that, the ONP positive level pulse signal of the adaptive on-time control circuit 115 is triggered by the RX signal. The on time of the primary power tube 103NP is the ONP positive level pulse width.

The secondary side turn-off/turn-on unit 123 detects a communication handshake process, and controls the secondary side power tube 103 NS to turn on and off after the primary side control circuit successfully handshakes with the secondary side.

In the primary side and secondary side handshaking process, the secondary side synchronous rectifier 104NS is kept off, and the primary side and the secondary side are prevented from being opened simultaneously.

If the primary side does not receive the communication handshake signals of the secondary side all the time, the primary side control circuit is automatically turned off after the oscillator module 112 controls the switch for tens of switching cycles, and the system is restarted.

When the handshake is successful, the switching of the primary power tube 103NP and the switching of the secondary synchronous rectifier 104NS are controlled only by the secondary control unit 120.

When the handshake is successful, the secondary synchronous rectifier 104NS can be controlled by the secondary control unit 120 to conduct.

RFB1 and RFB2 are output feedback voltage dividing resistors, a feedback signal FB of which is input to one end of the secondary adder circuit 128 and summed with an output signal FBB of the ripple injection module 125, and then the output FBs signal is connected to a negative input end of the first comparator 127, and a positive input end of the first comparator 127 is connected to the reference voltage value VR signal output by the reference voltage circuit 129.

When the FBS signal is less than the reference voltage value VR of the reference voltage circuit 129, it indicates that the output voltage VOUT is less than the target value, and the primary side is required to transfer energy to the secondary side through the switching operation of the primary power tube 103 NP. The conduction of the primary side through the primary side power tube 103NP is controlled by the output signal of the first comparator 127 and the output signal of the demagnetization time iterative control circuit 124 at the same time, and the turn-off of the primary side power tube 103NP is controlled by the adaptive conduction time control circuit 115.

When the FBS signal is smaller than the reference voltage value VR of the reference voltage circuit 129, the output signal ONTRIG of the first comparator 127 is a high level pulse, which indicates that the system needs the primary power tube 103NP to be conducted to transfer energy to the secondary side, and this signal serves as one of the conditions that the primary power tube 103NP is conducted. The timing of the conduction of the primary power tube 103NP is controlled by the demagnetization time iterative control circuit 124, which is another condition for the conduction of the primary power tube 103 NP. When the two conditions are met, the demagnetization time iterative control circuit 124 outputs a primary power tube 103NP switching request signal TX, which is modulated by the control signal modulation circuit 121, signal-coupled by the high-voltage capacitance isolation circuit 130, and demodulated by the control signal demodulation circuit 114, then transmitted to the primary generation signal RX, and then input to the adaptive on-time control circuit 115 through the alternative selector 111, thereby generating a switching signal ONP. The working states are circularly executed, so that the energy is transferred from the primary side to the secondary side.

The switching frequency of the system controlled by demagnetization iteration is variable, the right half plane zero point is eliminated, and the frequency jitter of the system improves the EMI performance of the system.

Fig. 2 is a control circuit loop control schematic diagram of the power conversion circuitry of the present invention. The signal of the secondary side output feedback circuit 107 and the signal of the ripple injection module 125 are summed by the adder 128 to generate an FBS signal, the FBS signal is input to the demagnetization time iteration control unit 124, when the system meets two conditions that the FBS voltage is less than the reference voltage value VR (v (FBS) < V (VR)) of the reference voltage circuit 129 and the demagnetization time Tdemn of the period is greater than or equal to the demagnetization time of the previous period minus the iteration error amount (Tdemn-1- Δ Tdem), the demagnetization time iteration control unit 124 firstly sends a signal through the secondary side turn-off/turn-on unit 123 in the secondary side control circuit 120, turns off the secondary side synchronous rectifier tube 104NS, and then sends a turn-on signal TX after delaying for several nanoseconds to the primary side power tube 103NP electrically connected to the primary side of the high frequency transformer 102, the signal is coupled and transmitted by the high voltage capacitor isolation circuit 130 to generate an RX signal, and is input to the NP adaptive turn-on time control circuit 115 of the primary side power tube, the self-adaptive on-time control circuit 115 controls the conduction of the primary power tube 103NP, the high-frequency transformer 102 stores energy in an excitation mode, meanwhile, the self-adaptive on-time control circuit 115 calculates the on-time of the primary power tube 103NP according to parameters such as primary bus voltage VIN and the like, the primary power tube 103NP is automatically turned off after the time is finished, the high-frequency transformer 102 demagnetizes and outputs energy to the secondary side, the secondary side detects that the demagnetization of the high-frequency transformer 102 starts, the secondary power tube 103 NS is turned on through the secondary side turn-off/turn-on unit 123, and simultaneously the secondary side detects in real time that a feedback signal is ready to start the work of the next period

Fig. 3 is a schematic diagram of the demagnetization time iterative control principle of the invention. In the figure, 301 represents a switching current waveform at the n-1 th time, 302 represents a switching current waveform at the n-th time, 310 represents the amount of change of the duty ratio from the n-1 st time to the n-th time, 311 represents the amount of change of the current from the n-1 st time to the n-th time, 312 represents the demagnetization time of the n-1 st time, 313 represents the demagnetization time of the n-th time switch of the invention, 314 represents the demagnetization time iteration error amount, and 315 represents the demagnetization time of the n-th time switch of the conventional control method.

When the duty ratio from the (n-1) th switching to the (n) th switching is slightly increased by Δ d, the demagnetization time of the conventional control method is correspondingly decreased by Δ d × Ts (where Ts represents the time of one switching cycle), as shown in the diagram 315, although the current is also increased by Δ IL due to the increase of the duty ratio, the average current output at the demagnetization stage is decreased due to the decrease of the demagnetization time, which results in the existence of a zero point on the right half plane of the system.

The demagnetization time is obtained by iterative computation, namely the demagnetization time of the nth switch is more than or equal to the demagnetization time of the nth-1 switch minus an iterative error quantity delta Tdem (Tdemn is more than or equal to Tdemn-1-delta Tdem), the iterative error quantity delta Tdem is controlled, and the output average current can be increased when the duty ratio of the system is increased, so that the right half plane zero point is eliminated, the loop bandwidth is increased, and the response speed of the system is improved.

Fig. 4 is a schematic diagram of the ripple injection signal waveform of the present invention. In the figure, FB denotes the output feedback signal, FBB is the ripple injection signal, FBs is the sum of the FB and FBB signals, VR is the reference voltage value of the reference voltage circuit 129, and ONTRIG is the output signal of the first comparator 127.

The ripple injection signal FBB from the ripple injection module 125 is synchronized with the ONTRIG signal, and when the ONTRIG signal changes from low to high, the FBB signal rises instantaneously, and drops exponentially after keeping tens of nanoseconds, and usually the change amplitude of the FBB signal is tens of millivolts.

Compared with the FB signal, the summed FBS signal has steep change at the valley bottom, and the output signal is inverted cleanly and uniquely after intersecting with the reference voltage value VR of the reference voltage circuit 129, so that the disorder of the system operation caused by the random generation of the ONTRIG signal due to noise is avoided. According to the method, the influence of signal noise interference during high-speed dynamic response is eliminated by a ripple injection method, and the stability of the system is improved.

FIG. 5 is a schematic diagram of an adaptive on-time control circuit according to the present invention. The circuit comprises a voltage division circuit 501, a first voltage control current source circuit 502, a first one-time trigger circuit 503, a first switch 505, a first capacitor 506, a first reference voltage source 507U1, a second comparator 508 and an inverter 509.

The voltage divider 501 and the first voltage-controlled current source circuit 502 generate a bias current IB proportional to the magnitude of the primary bus voltage VIN, and then the bias current IB enters the positive input terminal of the second comparator 508 through the node 534.

The first reference voltage source 507 outputs a voltage of a normally set level of volts to the negative input of the second comparator 508.

When the PON signal output by the output terminal of the alternative-selection selector 111 in the initial state is at a low level, the output signal of the first one-shot trigger circuit 503 is at a low level through the node 533, the first switch 505 is turned off, the bias current IB charges the first capacitor 506, the node 534 is at a high level and is higher than the output voltage of the first reference voltage source 507, the second comparator 508 outputs a high level, after passing through the inverter 509, the output signal PDRV is at a low level, the output signal PDRV is connected to the gate of the primary power tube 103NP, and the primary power tube 103NP is turned off.

When the PON signal changes from low to high, the first one-shot trigger circuit 503 outputs a positive pulse signal, the first switch 505 is turned on briefly, the first capacitor 506 discharges to ground quickly, the node 534 is at a zero level, the second comparator 508 outputs a low level, the PDRV signal changes from a low level to a high level, and the primary power tube 103NP is turned on. When the first switch 505 is turned on briefly and then turned off again, the bias current IB charges the first capacitor 506 again, the voltage at the node 534 continuously rises, and when the level of the node 534 is higher than the output voltage of the first reference voltage source 507, the second comparator 508 outputs a high level, the PDRV signal returns to a low level, and the primary power tube 103NP is turned off.

The turn-on of the primary power tube 103NP is synchronized with the rising edge of the PON signal, and the turn-off of the primary power tube 103NP is controlled by the charging time of the first capacitor 506.

The on-time Ton of the primary power tube 103NP is C (506) × V (507)/(1/k × G × VIN), the primary bus voltage VIN has the formula VIN × Ton ═ IL × Lp, and IL ═ C (506) × V (507)/(1/k × G × Lp) can be obtained, where C (506) is the capacitance of the first capacitor 506, V (507) is the voltage of the first reference voltage source 507, 1/k is the voltage division coefficient 501, G is the transconductance of 502, Lp is the primary inductance of the high-frequency transformer 102, and IL is the primary exciting current of the high-frequency transformer 102. Wherein the value range of C (506) is several-10 picofarads, and the value range of V (507) is several volts, such as 2 volts. The value range of 1/K is 0.001-0.005, and the value range of G is 10 e-6. The primary exciting current of the high-frequency transformer 102 is controlled by the constant, so that an exciting current sampling resistor is omitted, the system cost is reduced, and the system reliability is improved.

In fig. 6, under the high level control of the output terminal of the secondary side turn-off/turn-on unit 123, the second switch SW2 is turned on, the third switch SW3 instantaneously turns on and clears the residual charge of the second capacitor C2 under the action of the One Shot of the single pulse trigger circuit, and then the second voltage control current source circuit Ibias1 passes through the second switch SW2 and TdemⁿThe phase is charging the second capacitor C2, where TdemⁿThe charging time of (a) is t ═ C × V/I, where C is the second capacitor C2 in fig. 6, the charging current I is fixed, and the primary side bus voltage electrically connected to the primary side of the different high-frequency transformer 102 is constantThe VIN voltage corresponds to different t times. After the charging is finished, the voltage value will act on the positive input terminal of the first comparator 127 at the same time, and when the first comparator 127 meets the condition that the summation voltage value is smaller than the reference voltage value of the reference voltage circuit, the ONTRIG terminal outputs a high level, and the high level acts on the CP input terminal of the second D flip-flop at the same time, so that the Q output terminal of the second D flip-flop outputs a high level, and the fourth switch SW4 and the fifth switch SW5 are opened. The third capacitor C3 latches the charging time to Tdem^n-1The first comparator 127 outputs Tdem after the demagnetization time of the current period is more than or equal to the demagnetization time of the last period minus the iteration error quantity conditionⁿ≥Tdem^n-1- Δ Tdem; when the condition is satisfied, the comparison result of the high level is output, and the result is the TX on signal sent to the primary side control circuit by the control signal modulation circuit 121 in the secondary side control circuit 120.

In fig. 7, the output terminal of the first comparator 127, the second one-shot circuit OT2 outputs a high level, the seventh switch SW7 is turned on, and the fourth capacitor C4 is charged by the second reference voltage source U2, and the voltage value acts as the ripple injection signal FBB at the adder 128 terminal; when the output terminal ONTRIG of the first comparator 127 outputs a low level, the seventh switch SW7 is turned off, and the first resistor R provides a charge-discharging loop for the fourth capacitor C4.

In this specification, a particular feature, structure, material, or characteristic described is included in at least one embodiment or example of the invention. The above schematic representations do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.