阅读说明：本技术 自动平衡谐振能量方法及所用装置 (Method and apparatus for automatically balancing resonant energy ) 是由 孙建中 翁大丰 于 2021-02-08 设计创作，主要内容包括：本发明公开了一种自动平衡谐振能量装置：包括功能模块M、输出隔离变压器、MOS管Q1、MOS管Q2、原边MOS管Q、至少一套的谐振复位电路；功能模块M根据内部系统逻辑电路和反馈电压,控制MOS管Q1或MOS管Q2导通/截至。本发明还同时提供了一种自动平衡谐振能量方法。本发明不需要增加一个闭环调节环路来抑制激磁电感电流次开关频率震荡；本发明经过两个开关周期能迅速地消除激磁电感电流次开关频率震荡,而使用闭环调节环路来抑制激磁电感电流次开关频率震荡需要相当多开关周期才能使得激磁电感电流次开关频率震荡逐渐消除。(The invention discloses an automatic balance resonance energy device, which comprises: the device comprises a functional module M, an output isolation transformer, an MOS (metal oxide semiconductor) tube Q1, an MOS tube Q2, a primary side MOS tube Q and at least one set of resonance reset circuit; the functional module M controls the on/off of the MOS transistor Q1 or the MOS transistor Q2 according to the internal system logic circuit and the feedback voltage. The invention also provides a method for automatically balancing the resonance energy. According to the invention, a closed loop regulating loop is not required to be added to inhibit the secondary switching frequency oscillation of the exciting inductance current; the invention can rapidly eliminate the secondary switching frequency oscillation of the exciting inductance current through two switching cycles, and the secondary switching frequency oscillation of the exciting inductance current can be gradually eliminated only by using a closed loop regulating loop to inhibit the secondary switching frequency oscillation of the exciting inductance current through a plurality of switching cycles.)

1. Automatic balance resonance energy device, characterized by:

the device comprises a functional module M, an output isolation transformer, an MOS (metal oxide semiconductor) tube Q1, an MOS tube Q2, a primary side MOS tube Q and at least one set of resonance reset circuit;

the functional module M controls the on/off of the MOS transistor Q1 or the MOS transistor Q2 according to the internal system logic circuit and the feedback voltage.

2. The self-balancing resonant energy device of claim 1, wherein:

the functional module M controls the on/off of the MOS transistor Q1 or the MOS transistor Q2 according to the internal system logic circuit and the feedback voltages FB1 and FB 2.

3. The self-balancing resonant energy device of claim 2, wherein:

the output isolation transformer comprises a primary winding Np, a secondary winding Ns, a reset winding Nt1 and a reset winding Nt 2;

two sets of vibration reset circuits are provided;

one set of resonance reset circuit does: the resistor Ru1 and the resistor Rd1 are connected in series, and then are connected in parallel with the resonant capacitor Cr1 and the diode Dr1, and the resistor Rd1 is grounded; the resistor Ru1 is connected with the non-homonymous end of the reset winding Nt 1;

the other set of resonance reset circuit is as follows: the resistor Ru2 and the resistor Rd2 are connected in series, and then are connected in parallel with the resonant capacitor Cr2 and the diode Dr2, and the resistor Rd2 is grounded; the resistor Ru2 is connected with the non-homonymous end of the reset winding Nt 2;

a pin DR1 of the functional module M is connected with the grid electrode of the MOS transistor Q1; the source electrode of the MOS transistor Q1 is grounded, and the drain electrode of the MOS transistor Q1 is connected with the dotted terminal of the reset winding Nt 1; the MOS tube Q1 controls a resonance reset circuit formed by a resonance capacitor Cr1, a diode Dr1, a reset winding Nt1, a voltage division network of a resistor Ru1 and a resistor Rd 1;

a pin DR2 of the functional module M is connected with the grid electrode of the MOS transistor Q2; the source electrode of the MOS transistor Q2 is grounded, and the drain electrode of the MOS transistor Q2 is connected with the dotted terminal of the reset winding Nt 2; the MOS tube Q2 controls a resonance reset circuit formed by a voltage division network of a resonance capacitor Cr2, a diode Dr2, a reset winding Nt2 and resistors Ru2 and Rd 2;

pin FB1 and resistor R of functional module M_U1 and a resistance R_D1, feeding back a peak value and a valley value of a voltage waveform on the resonant capacitor, and controlling the conduction of the MOS tube Q1 to be cut off by the functional module according to the voltage waveform on the resonant capacitor;

pin FB2 and resistor R of functional module M_U2 and a resistance R_D2, feeding back the peak value and the valley value of the voltage waveform on the resonant capacitor, and controlling the conduction of the MOS tube Q2 to be cut off by the functional module according to the voltage waveform on the resonant capacitor;

a pin DR of the functional module M is connected with a grid electrode of the primary side MOS tube Q; the drain electrode of the primary side MOS tube Q is connected with the non-homonymous end of the primary side winding Np; the source electrode of the primary side MOS tube Q is respectively connected with the pin Ss and the resistor R of the functional module M_SConnected by a resistor R_SGrounding;

V_INis a primary side input voltage, V_INIs connected to the dotted terminal of the primary winding Np, V_INThe other end of the first and second electrodes is grounded;

the secondary winding Ns is connected to an input port of the secondary output circuit section.

4. The self-balancing resonant energy device of claim 1, wherein:

the functional module M controls the MOS tube Q1 or the MOS tube Q2 to be switched on/off according to the internal system logic circuit and the feedback voltage FB or the body diode current information of the MOS tubes Q1 and Q2; the MOS transistor Q1 controls a resonance reset network of the resonance capacitor Cr 1; the MOS transistor Q2 controls a resonant reset network of the resonant capacitor Cr 2.

5. The self-balancing resonant energy device of claim 4, wherein:

the output isolation transformer comprises a primary winding Np, a secondary winding Ns and a reset winding Nt;

the resonant reset circuit is a set;

the resonance reset circuit is as follows: the resonant capacitor Cr1 and the diode Dr1 are connected in parallel, and then are connected with the drain electrode of the MOS transistor Q1; the resonant capacitor Cr2 and the diode Dr2 are connected in parallel, and then are connected with the drain electrode of the MOS transistor Q2;

the grid of the MOS transistor Q1 is connected with a pin DR1 of the functional module M, and the source of the MOS transistor Q1 is connected with a pin Cs of the functional module M; the grid of the MOS transistor Q2 is connected with a pin DR2 of the functional module M, and the source of the MOS transistor Q2 is connected with a pin Cs of the functional module M; in the functional module M, a resistor is connected between the Cs pin and the ground of the functional module M;

the dotted terminal of the reset winding Nt is connected to the following terminals respectively: a pin FB of the functional module M, a resonant capacitor Cr1, a diode Dr1, a resonant capacitor Cr2 and a diode Dr 2; the non-homonymous end of the reset winding Nt is grounded;

a pin DR of the functional module M is connected with a grid electrode of the primary side MOS tube Q; the drain electrode of the primary side MOS tube Q is connected with the non-homonymous end of the primary side winding Np; the source electrode of the primary side MOS tube Q is respectively connected with a pin Ss and a resistor Rs of the functional module M, and the resistor Rs is grounded;

V_INis a primary side input voltage, V_INIs connected to the dotted terminal of the primary winding Np, V_INThe other end of the first and second electrodes is grounded;

the secondary winding Ns is connected to the input port of the secondary output circuit section.

6. An automatic balancing resonant energy device as claimed in any one of claims 1 to 3, wherein:

the resonance reset circuit is completed on the secondary side of the isolation transformer, and a functional block M1 is needed to be added on the primary side of the isolation transformer to receive the isolation driving pulse transmitted by the secondary side of the isolation transformer through the coupling pulse transformer or two coupling capacitors to control the conduction/cut-off of the primary side MOS tube Q;

the output information of the functional module M is coupled to the functional module M1 through a coupling pulse transformer or two high-voltage small capacitors C1 and C2 in an isolation mode; the functional module M1 has a corresponding port for receiving the output information of the functional module M transmitted by the isolation coupling of a pulse transformer or the isolation coupling of two high-voltage small capacitors C1 and C2;

a pin DR of the functional module M1 is connected with a grid electrode of a primary side MOS tube Q of the output isolation transformer; the source of the primary side MOS transistor Q is connected to the detection resistor Rs and the pin Ss of the functional module M1.

7. The self-balancing resonant energy device of claims 1, 4 or 5, wherein:

the resonance reset is controlled at the secondary side of the isolation transformer, the conduction of the primary side MOS tube Q of the isolation transformer is cut to the condition that the transmission is isolated by the driving pulse transmitted by the functional module M at the secondary side of the isolation transformer through the coupling pulse transformer or the two coupling capacitors, the functional module M1 outputs DR driving pulse to control the conduction and the disconnection of the primary side MOS tube Q of the isolation transformer through a ZVS switch according to the output information of the functional module M received by the driving pulse transmitted by the coupling pulse transformer or the two coupling capacitors and the functional module M1 feeds back voltage according to the detection resistor Rs;

the output information of the functional module M is coupled to the functional module M1 through a coupling pulse transformer or two high-voltage small capacitors C1 and C2 in an isolation mode; the functional module M1 has a corresponding port for receiving the output information of the functional module M transmitted by the isolation coupling of a pulse transformer or the isolation coupling of two high-voltage small capacitors C1 and C2;

a pin DR of the functional module M1 is connected with a grid electrode of a primary side MOS tube Q of the output isolation transformer; the source of the primary side MOS transistor Q is connected to the detection resistor Rs and the pin Ss of the functional module M1.

8. The method for automatically balancing the resonance energy is characterized in that: the secondary switching frequency oscillation of the exciting inductor current can be eliminated after two switching periods.

9. The method of automatically balancing resonant energy of claim 8, wherein any one of:

in the first mode, after a primary side MOS tube Q of the isolation transformer is cut off, the exciting inductive current i of the isolation transformer_LM(t) automatically resonates to the resonant capacitor Cr1 through the reset winding Nt1 and a body diode in the MOS tube Q1, and simultaneously, an excitation inductive current i of the isolation transformer_LM(t) automatically resonates to the resonant capacitor Cr2 through the reset winding Nt2 and a body diode in the MOS tube Q2 when the exciting inductive current i of the isolation transformer is in resonance_LM(t) decaying from Im to zero, the voltages on the two resonant capacitors Cr1 and Cr2 reach a peak value, and if the number of turns of Nt1 is equal to the number of turns of Nt2, the voltages on the two resonant capacitors Cr1 and Cr2 are finally equal no matter the initial voltages of the two resonant capacitors Cr1 and Cr 2; if the capacitance value Cr1 is Cr2, the exciting inductive current i of the isolation transformer_LM(t) during the period from Im value to zero, the secondary winding Ns, the reset winding Nt1 and the reset winding Nt2 of the isolation transformer excite the inductive current i in the form of coupled inductor_LM(t) automatically distributing the energy, and transmitting the energy to the resonant capacitor with the lowest energy storage, so that when the flyback multiple windings with the same number of turns are output, the output voltage of each winding is automatically balanced, and the output voltage of each winding with the same number of turns is the same;

second, after the primary MOS tube Q of the isolation transformer is cut off, the exciting inductive current i of the isolation transformer_LM(t) resonating to the resonant capacitor Cr1 and the resonant capacitor Cr2 via the reset winding Nt and the body diodes of MOS transistor Q1 and MOS transistor Q2 when the exciting inductor current i of the isolation transformer is_LM(t) the voltage on the two resonant capacitors Cr1 and Cr2 reaches the peak value no matter the initial voltage of the resonant capacitor Cr1 and the oscillating capacitor Cr2, and the voltages on the two resonant capacitors Cr1 and Cr2 are basically equal; due to the body diode action of the MOS transistor Q1 and the MOS transistor Q2, the resonance voltage of the reset winding Nt is always changed along with the voltage of the instantaneous lowest resonance capacitor Cr1 or the resonance capacitor Cr 2; if the voltage on the resonant capacitor Cr1 is lower than the voltage on the resonant capacitor Cr2, the exciting inductive current i of the isolation transformer_LM(t) only the resonant capacitor Cr1 is charged, and the voltage of the reset winding Nt is changed along with the voltage on the resonant capacitor Cr 1; such thatThe voltage on the resonant capacitor Cr1 is equal to the voltage on the resonant capacitor Cr2, and then the exciting inductance current i of the isolation transformer_LM(t) the resonance capacitor Cr1 and the resonance capacitor Cr2 are charged simultaneously until the peak voltage of the resonance capacitor Cr1 or the resonance capacitor Cr2 is reached; therefore, the exciting inductive current i in the isolation transformer_LM(t) in the period from Im value to zero, regardless of the initial voltage of the two resonant capacitors Cr1 and Cr2, the exciting inductor current i_LM(t) energy is automatically distributed to the resonance capacitor Cr1 and the resonance capacitor Cr2, and the final energy storage of the resonance capacitor Cr1 and the resonance capacitor Cr2 are basically equal, or when the voltage of the resonance capacitor Cr1 is lower than the initial voltage of the resonance capacitor Cr2, the exciting inductance current of the isolation transformer only charges the resonance capacitor Cr1 through the reset winding Nt until the exciting inductance current i of the isolation transformer_LM(t) decays from Im to zero.

10. The method of automatically balancing resonant energy of claim 9, wherein:

the resonance reset control is carried out on the secondary side of the isolation transformer to ensure that the isolation transformer can effectively perform resonance reset, and the primary side MOS tube Q of the isolation transformer is switched on and off by a ZVS switch.

Technical Field

The invention relates to a device for automatically balancing resonant energy and a corresponding method.

Background

As shown in fig. 1, in a currently existing forward converter adopting resonance reset, energy corresponding to a current in an excitation inductor Lm of an isolation transformer resonates with energy corresponding to a voltage of a resonant capacitor Cr to perform energy exchange, so that a current in the excitation inductor Lm of the isolation transformer is reversed, reset of the isolation transformer is completed, and a ZVS conduction condition may be provided for a primary MOS transistor Q1 of the isolation transformer. The energy corresponding to the current of the excitation inductor Lm of the isolation transformer directly corresponds to the voltage-second product corresponding to the conduction period of the primary MOS transistor Q1 of the isolation transformer, and obviously, the larger the corresponding voltage-second product is, the larger the current in the corresponding excitation inductor Lm is. However, as a result of resonating with energy corresponding to the current of the magnetizing inductance Lm of the isolation transformer and energy corresponding to the voltage of the resonant capacitor Cr, the current in the magnetizing inductance Lm of the isolation transformer is reversed, that is, after the instantaneous value Im of the current of the magnetizing inductance Lm of the isolation transformer at the turn-off time of the primary MOS transistor Q1 resonates with the resonant capacitor, the current of the magnetizing inductance of the isolation transformer becomes the value-Im. Obviously, when the voltage-second product corresponding to the conduction period of the primary side MOS transistor of the isolation transformer changes rapidly, the magnitude of the exciting inductance current of the isolation transformer corresponding to each switching period also changes rapidly.

The resonance reset method can generate secondary switching frequency oscillation caused by exciting inductance current of the isolation transformer, and comprises the following steps: as shown in fig. 1, in the current switching cycle, the exciting inductor current increases linearly from zero in the on-time of the primary side MOS transistor Q1 of the isolation transformer, which is fixed correspondingly, and the exciting inductor current i is at the turn-off time of the primary side MOS transistor Q1 of the isolation transformer_LM(t) increasing to the Im value; after the primary side MOS tube Q1 of the isolation transformer is cut off, the inductive current i is excited_LMAnd (t) resetting the resonance with the resonance capacitor Cr to change the exciting inductor current from Im to-Im. (specifically, the resonant reset process is described as follows in the circuit shown in FIG. 1: the current i of the magnetizing inductor Lm_LM(t) resonating with a resonance reset circuit formed by a winding Nt, a body diode of a MOS tube Q2 and a resonance capacitor Cr; exciting inductive current i of isolation transformer_LM(t) the voltage of the resonant capacitor Cr is attenuated to zero by Im, the voltage of the resonant capacitor Cr is increased to a peak value from zero, and the MOS tube Q2 can be conducted under the ZVS condition because the body diode of the MOS tube Q2 is conducted; as the MOS tube Q2 is conducted under the ZVS condition, the resonance capacitor Cr continues to resonate with the exciting inductance Lm of the isolation transformer until the voltage of the resonance capacitor Cr is attenuated to zero from the peak value, the parallel diode Dr of the resonance capacitor Cr is conducted, and the current i of the exciting inductance Lm of the isolation transformer is conducted_LM(t) changes from zero to an Im value); in the conduction time of the primary side MOS tube Q1 of the isolation transformer fixed correspondingly in the next switching period, the current i of the exciting inductor Lm_LM(t) starting to increase linearly from-Im, and exciting an inductor Lm current i at the moment when a primary side MOS (metal oxide semiconductor) tube Q1 of the isolation transformer is turned off_LM(t) increasing from-Im to 0 (set to extreme)(ii) a After the primary MOS tube Q1 of the isolation transformer is cut off, the exciting inductance Lm resonates with the resonant capacitor through the corresponding resonant reset circuit, and the current i of the exciting inductance Lm of the isolation transformer_LM(t) also becomes a 0 value. Thus exciting the current i of the inductor Lm_LM(t) the current values at the turn-off time of the primary side MOS transistor Q1 of the isolation transformer in the adjacent switching period are respectively 0 and Im, which alternately appear as shown in fig. 2, and the repetition frequency is one half of the switching frequency, which is called the exciting inductor current secondary switching frequency oscillation.

Obviously, in the conduction time of the primary side MOS tube Q1 of the isolation transformer, the current flowing through the primary side MOS tube Q1 is the exciting inductance Lm current i of the isolation transformer_LM(t) sum of reflected current of output current of forward converter, and current i of exciting inductor Lm_LMThe (t) times of switching frequency oscillation will naturally affect the magnitude of the output current of the forward converter. Therefore, it is necessary to overcome and suppress the secondary switching frequency oscillation of the exciting inductor current to ensure the accurate control of the output current of the forward converter.

Disclosure of Invention

The invention provides a device for automatically balancing resonance energy and a corresponding method.

In order to solve the above technical problems, the present invention provides an automatic balancing resonance energy apparatus:

the device comprises a functional module M, an output isolation transformer, an MOS (metal oxide semiconductor) tube Q1, an MOS tube Q2, a primary side MOS tube Q and at least one set of resonance reset circuit;

the functional module M controls the on/off of the MOS transistor Q1 or the MOS transistor Q2 according to the internal system logic circuit and the feedback voltage.

As an improvement of the self-balancing resonant energy device of the present invention:

the functional module M controls the on/off of the MOS tube Q1 or the MOS tube Q2 according to the internal system logic circuit and feedback voltages FB1 and FB2 (namely the voltage division network outputs of Ru1 and Rd1, Ru2 and Rd 2).

That is, the resonant reset circuit controlled by the MOS transistor Q1 resets in the current switching period, and the resonant reset circuit controlled by the MOS transistor Q2 resets in the next switching period; this alternately resets.

As a further improvement of the self-balancing resonant energy device of the present invention:

the output isolation transformer comprises a primary winding Np, a secondary winding Ns, a reset winding Nt1 and a reset winding Nt 2;

two sets of vibration reset circuits are provided;

one set of resonance reset circuit does: the resistor Ru1 and the resistor Rd1 are connected in series, and then are connected in parallel with the resonant capacitor Cr1 and the diode Dr1, and the resistor Rd1 is grounded; the resistor Ru1 is connected with the non-homonymous end of the reset winding Nt 1;

the other set of resonance reset circuit is as follows: the resistor Ru2 and the resistor Rd2 are connected in series, and then are connected in parallel with the resonant capacitor Cr2 and the diode Dr2, and the resistor Rd2 is grounded; the resistor Ru2 is connected with the non-homonymous end of the reset winding Nt 2;

a pin DR1 of the functional module M is connected with the grid electrode of the MOS transistor Q1; the source electrode of the MOS transistor Q1 is grounded, and the drain electrode of the MOS transistor Q1 is connected with the dotted terminal of the reset winding Nt 1; the MOS tube Q1 controls a resonance reset circuit formed by a resonance capacitor Cr1, a diode Dr1, a reset winding Nt1, a voltage division network of a resistor Ru1 and a resistor Rd 1;

a pin DR2 of the functional module M is connected with the grid electrode of the MOS transistor Q2; the source electrode of the MOS transistor Q2 is grounded, and the drain electrode of the MOS transistor Q2 is connected with the dotted terminal of the reset winding Nt 2; the MOS tube Q2 controls a resonance reset circuit formed by a voltage division network of a resonance capacitor Cr2, a diode Dr2, a reset winding Nt2 and resistors Ru2 and Rd 2;

pin FB1 and resistor R of functional module M_U1 and a resistance R_D1, feeding back a peak value and a valley value of a voltage waveform on the resonant capacitor, and controlling the conduction of the MOS tube Q1 to be cut off by the functional module according to the voltage waveform on the resonant capacitor;

pin FB2 and resistor R of functional module M_U2 and a resistance R_D2, feeding back the peak value and the valley value of the voltage waveform on the resonant capacitor, and controlling the conduction of the MOS tube Q2 to be cut off by the functional module according to the voltage waveform on the resonant capacitor;

a pin DR of the functional module M is connected with a grid electrode of the primary side MOS tube Q; the drain electrode of the primary side MOS tube Q is connected with the non-homonymous end of the primary side winding Np; source of primary side MOS tube QThe poles of the resistor are respectively connected with the pins Ss and the resistors R of the functional module M_SConnected by a resistor R_SGrounding;

V_INis a primary side input voltage, V_INIs connected to the dotted terminal of the primary winding Np, V_INThe other end of the first and second electrodes is grounded;

the secondary winding Ns is connected to an input port of the secondary output circuit section.

As a further improvement of the self-balancing resonant energy device of the present invention:

the functional module M controls the MOS transistor Q1 or the MOS transistor Q2 to be switched on/off according to the internal system logic circuit and the feedback voltage FB (namely, the voltage waveform of the detection winding Nt) or the body diode current information of the MOS transistors Q1 and Q2; the MOS transistor Q1 controls a resonance reset network of the resonance capacitor Cr 1; the MOS transistor Q2 controls a resonant reset network of the resonant capacitor Cr 2.

As a further improvement of the self-balancing resonant energy device of the present invention:

the output isolation transformer comprises a primary winding Np, a secondary winding Ns and a reset winding Nt;

the resonant reset circuit is a set;

the resonance reset circuit is as follows: the resonant capacitor Cr1 and the diode Dr1 are connected in parallel, and then are connected with the drain electrode of the MOS transistor Q1; the resonant capacitor Cr2 and the diode Dr2 are connected in parallel, and then are connected with the drain electrode of the MOS transistor Q2;

the grid of the MOS transistor Q1 is connected with a pin DR1 of the functional module M, and the source of the MOS transistor Q1 is connected with a pin Cs of the functional module M; the grid of the MOS transistor Q2 is connected with a pin DR2 of the functional module M, and the source of the MOS transistor Q2 is connected with a pin Cs of the functional module M; in the functional module M, a resistor is connected between the Cs pin and the ground of the functional module M;

the dotted terminal of the reset winding Nt is connected to the following terminals respectively: a pin FB of the functional module M, a resonant capacitor Cr1, a diode Dr1, a resonant capacitor Cr2 and a diode Dr 2; the non-homonymous end of the reset winding Nt is grounded;

a pin DR of the functional module M is connected with a grid electrode of the primary side MOS tube Q; the drain electrode of the primary side MOS tube Q is connected with the non-homonymous end of the primary side winding Np; the source electrode of the primary side MOS tube Q is respectively connected with a pin Ss and a resistor Rs of the functional module M, and the resistor Rs is grounded;

V_INis a primary side input voltage, V_INIs connected to the dotted terminal of the primary winding Np, V_INThe other end of the first and second electrodes is grounded;

the secondary winding Ns is connected to the input port of the secondary output circuit section.

As a further improvement of the self-balancing resonant energy device of the present invention:

the resonance reset circuit is completed on the secondary side of the isolation transformer, and a functional block M1 is needed to be added on the primary side of the isolation transformer to receive the isolation driving pulse transmitted by the secondary side of the isolation transformer through the coupling pulse transformer or two coupling capacitors to control the conduction/cut-off of the primary side MOS tube Q;

the output information of the functional module M is coupled to the functional module M1 through a coupling pulse transformer or two high-voltage small capacitors C1 and C2 in an isolation mode; the functional module M1 has a corresponding port for receiving the output information of the functional module M transmitted by the isolation coupling of a pulse transformer or the isolation coupling of two high-voltage small capacitors C1 and C2;

a pin DR of the functional module M1 is connected with a grid electrode of a primary side MOS tube Q of the output isolation transformer; the source of the primary side MOS transistor Q is connected to the detection resistor Rs and the pin Ss of the functional module M1.

As a further improvement of the self-balancing resonant energy device of the present invention:

the resonance reset is controlled at the secondary side of the isolation transformer, the conduction of the primary side MOS tube Q of the isolation transformer is cut to the condition that the transmission is isolated by the driving pulse transmitted by the functional module M at the secondary side of the isolation transformer through the coupling pulse transformer or the two coupling capacitors, the functional module M1 outputs DR driving pulse to control the conduction and the disconnection of the primary side MOS tube Q of the isolation transformer through a ZVS switch according to the output information of the functional module M received by the driving pulse transmitted by the coupling pulse transformer or the two coupling capacitors and the functional module M1 feeds back voltage according to the detection resistor Rs;

the output information of the functional module M is coupled to the functional module M1 through a coupling pulse transformer or two high-voltage small capacitors C1 and C2 in an isolation mode; the functional module M1 has a corresponding port for receiving the output information of the functional module M transmitted by the isolation coupling of a pulse transformer or the isolation coupling of two high-voltage small capacitors C1 and C2;

a pin DR of the functional module M1 is connected with a grid electrode of a primary side MOS tube Q of the output isolation transformer; the source of the primary side MOS transistor Q is connected to the detection resistor Rs and the pin Ss of the functional module M1.

The invention also provides a method for automatically balancing the resonance energy, which comprises the following steps: the secondary switching frequency oscillation of the exciting inductor current can be eliminated (rapidly eliminated) through two switching cycles, and the secondary switching frequency oscillation of the exciting inductor current can be gradually eliminated by using a closed loop regulating loop to inhibit the secondary switching frequency oscillation of the exciting inductor current through a plurality of switching cycles.

The improvement of the method for automatically balancing the resonance energy is any one of the following methods:

in the first mode, after a primary side MOS tube Q of the isolation transformer is cut off, the exciting inductive current i of the isolation transformer_LM(t) automatically resonates to the resonant capacitor Cr1 through the reset winding Nt1 and a body diode in the MOS tube Q1, and simultaneously, an excitation inductive current i of the isolation transformer_LM(t) automatically resonates to the resonant capacitor Cr2 through the reset winding Nt2 and a body diode in the MOS tube Q2 when the exciting inductive current i of the isolation transformer is in resonance_LM(t) decaying from Im to zero, the voltages on the two resonant capacitors Cr1 and Cr2 reach a peak value, and if the number of turns of Nt1 is equal to the number of turns of Nt2, the voltages on the two resonant capacitors Cr1 and Cr2 are finally equal no matter the initial voltages of the two resonant capacitors Cr1 and Cr 2; if the capacitance value Cr1 is Cr2, the exciting inductive current i of the isolation transformer_LM(t) during the period from Im value to zero, the secondary winding Ns, the reset winding Nt1 and the reset winding Nt2 of the isolation transformer excite the inductive current i in the form of coupled inductor_LM(t) automatically distributing the energy, and transmitting the energy to the resonant capacitor with the lowest energy storage, so that when the flyback multiple windings with the same number of turns are output, the output voltage of each winding is automatically balanced, and the output voltage of each winding with the same number of turns is the same;

second mode, after the primary side MOS tube Q of the isolation transformer is cut off, the excitation inductance of the isolation transformer is electrifiedStream i_LM(t) resonating to the resonant capacitor Cr1 and the resonant capacitor Cr2 via the reset winding Nt and the body diodes of MOS transistor Q1 and MOS transistor Q2 when the exciting inductor current i of the isolation transformer is_LM(t) the voltage on the two resonant capacitors Cr1 and Cr2 reaches the peak value no matter the initial voltage of the resonant capacitor Cr1 and the oscillating capacitor Cr2, and the voltages on the two resonant capacitors Cr1 and Cr2 are basically equal; due to the body diode action of the MOS transistor Q1 and the MOS transistor Q2, the resonance voltage of the reset winding Nt is always changed along with the voltage of the instantaneous lowest resonance capacitor Cr1 or the resonance capacitor Cr 2; if the voltage on the resonant capacitor Cr1 is lower than the voltage on the resonant capacitor Cr2, the exciting inductive current i of the isolation transformer_LM(t) only the resonant capacitor Cr1 is charged, and the voltage of the reset winding Nt is changed along with the voltage on the resonant capacitor Cr 1; thus, the voltage on the resonant capacitor Cr1 is equal to the voltage on the resonant capacitor Cr2, and then the exciting inductance current i of the isolation transformer_LM(t) the resonance capacitor Cr1 and the resonance capacitor Cr2 are charged simultaneously until the peak voltage of the resonance capacitor Cr1 or the resonance capacitor Cr2 is reached; therefore, the exciting inductive current i in the isolation transformer_LM(t) in the period from Im value to zero, regardless of the initial voltage of the two resonant capacitors Cr1 and Cr2, the exciting inductor current i_LM(t) energy is automatically distributed to the resonance capacitor Cr1 and the resonance capacitor Cr2, and the final energy storage of the resonance capacitor Cr1 and the resonance capacitor Cr2 are basically equal, or when the voltage of the resonance capacitor Cr1 is lower than the initial voltage of the resonance capacitor Cr2, the exciting inductance current of the isolation transformer only charges the resonance capacitor Cr1 through the reset winding Nt until the exciting inductance current i of the isolation transformer_LM(t) decays from Im to zero.

As a further improvement of the method for automatically balancing the resonance energy of the invention: the resonance reset control is carried out on the secondary side of the isolation transformer to ensure that the isolation transformer can effectively perform resonance reset, and the primary side MOS tube Q of the isolation transformer is switched on and off by a ZVS switch.

The invention can effectively restrain and overcome the excitation inductance current secondary switching frequency oscillation; the method comprises the following specific steps:

1. a closed loop regulating loop is not required to be added to inhibit the secondary switching frequency oscillation of the exciting inductance current;

2. the secondary switching frequency oscillation of the exciting inductance current can be rapidly eliminated through two switching cycles, and the secondary switching frequency oscillation of the exciting inductance current can be gradually eliminated only by using a closed loop regulating loop to inhibit the secondary switching frequency oscillation of the exciting inductance current through a plurality of switching cycles;

3. the output current can be accurately controlled without considering the secondary switching frequency oscillation of the exciting inductance current.

4. Because the secondary switching frequency oscillation of the exciting inductance current is rapidly eliminated, the voltage peak value of the reset resonant capacitor corresponding to the exciting inductance current is lower, and the turn-off voltage borne by the primary side MOS is lower.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a presently existing forward converter employing resonant reset;

FIG. 2 is a diagram of an excitation inductor current subswitch frequency oscillation waveform of FIG. 1;

FIG. 3 is a circuit diagram for automatically balancing resonance energy according to embodiment 1;

FIG. 4 is a circuit diagram for automatically balancing resonance energy according to embodiment 2;

FIG. 5 is a graph of the driving pulse and the counter-stress inductor current waveform of the primary side MOS transistor controlled by the circuit for automatically balancing resonant energy of the embodiment 2;

in fig. 5, the upper diagram is the driving pulse waveform of the primary side MOS transistor of the isolation transformer, and the lower diagram is the exciting inductance current waveform of the isolation transformer;

FIG. 6 is a circuit diagram of the embodiment 3 for automatically balancing the resonance energy at the secondary side of the isolation transformer;

fig. 7 is a circuit diagram of the self-balancing of resonant energy at the secondary side of the isolation transformer as described in example 4.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

example 1: an automatic balancing resonant energy device, as shown in fig. 3:

the device comprises a functional module M, an output isolation transformer, an MOS (metal oxide semiconductor) tube Q1, an MOS tube Q2, a primary side MOS tube Q and two sets of resonance reset circuits;

the output isolation transformer comprises a primary winding Np, a secondary winding Ns, a reset winding Nt1 and a reset winding Nt2, and the 4 windings are wound on the same magnetic core;

one set of resonance reset circuit does: the resistor Ru1 and the resistor Rd1 are connected in series, and then are connected in parallel with the resonant capacitor Cr1 and the diode Dr1, and the resistor Rd1 is grounded; the resistor Ru1 is connected with the non-homonymous end of the reset winding Nt 1;

the other set of resonance reset circuit is as follows: the resistor Ru2 and the resistor Rd2 are connected in series, and then are connected in parallel with the resonant capacitor Cr2 and the diode Dr2, and the resistor Rd2 is grounded; the resistor Ru2 is connected with the non-homonymous end of the reset winding Nt 2;

a pin DR1 of the functional module M is connected with the grid electrode of the MOS transistor Q1; the source electrode of the MOS transistor Q1 is grounded, and the drain electrode of the MOS transistor Q1 is connected with the dotted terminal of the reset winding Nt 1; the MOS transistor Q1 controls a resonant reset circuit formed by a resonant capacitor Cr1, a diode Dr1, a reset winding Nt1 and a voltage division network of a resistor Ru1 and a resistor Rd 1.

A pin DR2 of the functional module M is connected with the grid electrode of the MOS transistor Q2; the source electrode of the MOS transistor Q2 is grounded, and the drain electrode of the MOS transistor Q2 is connected with the dotted terminal of the reset winding Nt 2; the MOS transistor Q2 controls a resonant reset circuit formed by a voltage division network of a resonant capacitor Cr2, a diode Dr2, a reset winding Nt2 and resistors Ru2 and Rd 2.

Pin FB1 and resistor R of functional module M_U1 and a resistance R_D1, feeding back a peak value and a valley value of a voltage waveform on the resonant capacitor, and controlling the conduction of the MOS tube Q1 to be cut off by the functional module according to the voltage waveform on the resonant capacitor;

pin FB2 and resistor R of functional module M_U2 and a resistance R_D2, feeding back the peak value and the valley value of the voltage waveform on the resonant capacitor, and controlling the conduction of the MOS tube Q2 to be cut off by the functional module according to the voltage waveform on the resonant capacitor;

a pin DR of the functional module M is connected with a grid electrode of the primary side MOS tube Q; the drain electrode of the primary side MOS tube Q is connected with the non-homonymous end of the primary side winding Np; the source electrode of the primary side MOS tube Q is respectively connected with the pin Ss and the resistor R of the functional module M_SConnected by a resistor R_SAnd (4) grounding.

V_INIs a primary side input voltage, V_INIs connected to the dotted terminal of the primary winding Np, V_INThe other end of the first and second electrodes is grounded;

the secondary winding Ns is connected to an input port of the secondary output circuit section.

That is, compared with the conventional forward converter as shown in fig. 1, embodiment 1 of the present invention adds a set of resonant reset circuits. The two sets of resonance reset circuits alternately perform resonance reset, and specifically, the functional module M controls the conduction/cut-off of the MOS transistor Q1 or the MOS transistor Q2 according to an internal system logic circuit and feedback voltages FB1 and FB2 (i.e., voltage division network outputs of Ru1 and Rd1, and Ru2 and Rd 2); that is, the resonant reset circuit controlled by the MOS transistor Q1 resets in the current switching period, and the resonant reset circuit controlled by the MOS transistor Q2 resets in the next switching period; this alternately resets.

Description of the drawings: a D-type trigger can be used in a logic circuit of an internal system of the functional module M to divide the switching frequency, and the output Q end and the QB end of the D-type trigger respectively control the MOS transistors Q1 and Q2 to carry out resonance reset, so that the functional module M can be easily prepared and obtained according to the technical scheme provided by the invention.

In fig. 3, after the primary side MOS transistor Q of the isolation transformer is cut off, the exciting inductor current i of the isolation transformer_LM(t) automatically resonates to the resonant capacitor Cr1 through the reset winding Nt1 and a body diode in the MOS tube Q1, and simultaneously, an excitation inductive current i of the isolation transformer_LM(t) automatically resonates to the resonant capacitor Cr2 through the reset winding Nt2 and a body diode in the MOS tube Q2 when the exciting inductive current i of the isolation transformer is in resonance_LM(t) decaying from Im to zero, the voltages on the two resonant capacitors Cr1 and Cr2 reach a peak value, and if the number of turns of Nt1 is equal to the number of turns of Nt2, the voltages on the two resonant capacitors Cr1 and Cr2 are finally equal no matter the initial voltages of the two resonant capacitors Cr1 and Cr 2; if the capacitance value C isr1 ═ Cr2, i.e. the charges stored in the two resonant capacitors Cr1 and Cr2 are equal, and the exciting inductor current i in the isolating transformer is equal_LM(t) during the period from Im value to zero, the secondary winding Ns, the reset winding Nt1 and the reset winding Nt2 of the isolation transformer excite the inductive current i in the form of coupled inductor_LMAnd (t) automatically distributing the energy, namely, transmitting the energy to the resonant capacitor with the lowest energy storage, namely, automatically balancing the output voltage of each winding when the flyback multiple windings with the same number of turns are output, so that the output voltages of the windings with the same number of turns are the same.

Due to this characteristic, the exciting inductor current i in the isolation transformer_LMDuring the period of decay from the Im value to zero, if Nt1 is Nt2 and Cr1 is Cr2, the energy of the magnetizing inductor current is automatically distributed to the resonant capacitors Cr1 and Cr2 no matter the initial voltage of the two resonant capacitors Cr1 and Cr2, and the final energy storage of the resonant capacitors Cr1 and Cr2 is basically equal. Specifically, the method comprises the following steps: if the voltage on the resonant capacitor Cr1 is lower than the voltage on the resonant capacitor Cr2, the exciting inductive current i of the isolation transformer_LM(t) the resonant capacitor Cr1 will be charged only via the reset winding Nt1, so that the voltage on the resonant capacitor Cr1 is equal to the voltage on the resonant capacitor Cr2, and then the magnetizing inductor current of the isolation transformer will simultaneously charge the resonant capacitor Cr1 via the reset winding Nt1 and the resonant capacitor Cr2 via the reset winding Nt2, until the peak voltage of the resonant capacitor Cr1 or Cr2 is reached. It is also possible that the Cr1 voltage is always lower than the initial voltage of Cr2, the exciting inductor current of the isolation transformer will charge only the resonant capacitor Cr1 through the reset winding Nt1 until the exciting inductor current i of the isolation transformer_LM(t) decays from Im to zero.

In the exciting inductance current i_LMAfter (t) decays from Im to zero, the obtained reverse exciting inductor current will not necessarily be-Im, and will be determined according to the initial values of the two resonant capacitors Cr1 and Cr2, regardless of whether the resonant reset circuit controlled by the MOS transistor Q1 or the resonant reset circuit controlled by the MOS transistor Q2 operates.

The method comprises the following specific steps:

1) assuming that the initial voltages of the two resonant capacitors Cr1 and Cr2 are both zero, the obtained inverse excitation inductance current is-Im/2;

2) when the steady-state resonance is reset, assuming that the initial voltage of the resonance capacitor Cr1 is zero and the initial voltage of the resonance capacitor Cr2 is a peak value, the obtained inverse excitation inductance current is-Im; and vice versa;

3) and assuming that the initial voltages of the two resonant capacitors Cr1 and Cr2 are not zero, the obtained reverse-phase excitation inductance current is determined according to one half of the total energy obtained by superposing all the energies.

Obviously, at the time of steady-state resonance reset, the resonance reset circuit controlled by the MOS transistor Q1 or the MOS transistor Q2 is reset at the current switching period (the operation of the reset circuit has been described in the background, and is not repeated here); the resonance reset circuit controlled by the MOS transistor Q2 or the MOS transistor Q1 resets in the next switching period; the alternating resetting is to make the initial voltage of the two resonant capacitors Cr1 and Cr2 alternately zero and peak, which makes the resulting inverse exciting inductor current be-Im.

When the input voltage fluctuates or the output power increases, the conduction time of the primary side MOS tube Q of the isolation transformer suddenly increases to cause the exciting inductance current i_LM(t) when the current value suddenly increases to Im + Δ, the resonant reset circuit controlled by the MOS transistor Q1 (or the MOS transistor Q2) resets in the current switching period, and the corresponding resonant reset circuit controlled by the MOS transistor Q2 (or the MOS transistor Q1) resets in the next switching period, so that the amplitude of the obtained reverse-phase exciting inductor current is reduced; because when the inductive current i is excited_LM(t) the sudden increase will cause the peak voltage of both the resonant capacitors Cr1 and Cr2 to increase, i.e. the resonant capacitor Cr1 or Cr2 increases from the original peak voltage to a new peak value; alternatively, the resonant capacitor Cr2 or Cr1 is increased from zero voltage to a new peak voltage. Thus, the energy corresponding to the newly added excitation inductor current Im + Δ is absorbed by the two resonant capacitors Cr1 and Cr2, respectively, so that the energy added to each of the two resonant capacitors Cr1 and Cr2 is smaller than the energy added to one resonant capacitor Cr shown in fig. 1, and the amplitude of the inverse excitation inductor current value generated by the new peak voltage of the two resonant capacitors Cr1 or Cr2 is smaller than Im + Δ. Thus, the resonance reset is controlled alternately through MOS transistors Q1 and Q2,the instantaneous values of the exciting inductance current at the turn-off time of the primary side MOS tube Q of each adjacent switching period can be automatically and rapidly adjusted to be basically the same without any regulating loop.

Example 2, as shown in figure 4.

One resonant reset winding is omitted from the comparison of fig. 3 corresponding to example 1. The functional module M controls the MOS transistor Q1 or the MOS transistor Q2 to be switched on/off according to the internal system logic circuit and the feedback voltage FB (namely, the voltage waveform of the detection winding Nt) or the body diode current information of the MOS transistors Q1 and Q2; the MOS transistor Q1 controls a resonance reset network of the resonance capacitor Cr 1; the MOS transistor Q2 controls a resonant reset network of the resonant capacitor Cr 2. The resonant capacitance Cr1 ═ Cr 2.

The method specifically comprises the following steps:

the device comprises a functional module M, an output isolation transformer, an MOS (metal oxide semiconductor) tube Q1, an MOS tube Q2, a primary side MOS tube Q and a set of resonance reset circuit;

the output isolation transformer comprises a primary winding Np, a secondary winding Ns and a reset winding Nt;

the resonance reset circuit is as follows: the resonant capacitor Cr1 and the diode Dr1 are connected in parallel, and then are connected with the drain electrode of the MOS transistor Q1; the resonant capacitor Cr2 and the diode Dr2 are connected in parallel, and then are connected with the drain electrode of the MOS transistor Q2;

the grid of the MOS transistor Q1 is connected with a pin DR1 of the functional module M, and the source of the MOS transistor Q1 is connected with a pin Cs of the functional module M; the grid of the MOS transistor Q2 is connected with a pin DR2 of the functional module M, and the source of the MOS transistor Q2 is connected with a pin Cs of the functional module M; in the functional module M, a detection resistor is connected between the Cs pin and the ground of the functional module M to detect a change of the sum of the total currents of the MOS transistors Q1 and Q2.

The dotted terminal of the reset winding Nt is connected to the following terminals respectively: a pin FB of the functional module M, a resonant capacitor Cr1, a diode Dr1, a resonant capacitor Cr2 and a diode Dr 2; the non-homonymous end of the reset winding Nt is grounded;

a pin DR of the functional module M is connected with a grid electrode of the primary side MOS tube Q; the drain electrode of the primary side MOS tube Q is connected with the non-homonymous end of the primary side winding Np; the source electrode of the primary side MOS tube Q is respectively connected with the pin Ss and the resistor Rs of the functional module M, and the resistor Rs is grounded.

V_INIs a primary side input voltage, V_INIs connected to the dotted terminal of the primary winding Np, V_INThe other end of the first and second electrodes is grounded;

the secondary winding Ns is connected to the input port of the secondary output circuit section.

In fig. 4, after the primary side MOS transistor Q of the isolation transformer is cut off, the exciting inductor current i of the isolation transformer_LM(t) resonating to the resonant capacitor Cr1 and the resonant capacitor Cr2 via the reset winding Nt and the body diodes of MOS transistor Q1 and MOS transistor Q2 when the exciting inductor current i of the isolation transformer is_LM(t) decays from the Im value to zero, and the voltages on the two resonant capacitors Cr1 and Cr2 reach peak values no matter the initial voltages of the resonant capacitor Cr1 and the resonant capacitor Cr2, and the voltages on the two resonant capacitors Cr1 and Cr2 are basically equal. Due to the body diode action of the MOS transistor Q1 and the MOS transistor Q2, the resonance voltage of the reset winding Nt is always changed along with the voltage of the instantaneous lowest resonance capacitor Cr1 or the resonance capacitor Cr 2. That is, if the voltage on the resonant capacitor Cr1 is lower than the voltage on the resonant capacitor Cr2, the exciting inductor current i of the isolation transformer is_LM(t) only the resonant capacitor Cr1 is charged, and the voltage of the reset winding Nt is changed along with the voltage on the resonant capacitor Cr 1; thus, the voltage on the resonant capacitor Cr1 is equal to the voltage on the resonant capacitor Cr2, and then the exciting inductance current i of the isolation transformer_LM(t) the resonance capacitor Cr1 and the resonance capacitor Cr2 will be charged simultaneously until the peak voltage of the resonance capacitor Cr1 or the resonance capacitor Cr2 is reached. It is this characteristic that the exciting inductive current i in the isolation transformer_LM(t) in the period from Im value to zero, regardless of the initial voltage of the two resonant capacitors Cr1 and Cr2, the exciting inductor current i_LMThe energy of (t) is automatically distributed to the resonant capacitor Cr1 and the resonant capacitor Cr2, and the final stored energy of the resonant capacitor Cr1 and the resonant capacitor Cr2 is basically equal. It is also possible that the voltage of the resonant capacitor Cr1 is always lower than the initial voltage of the resonant capacitor Cr2, and the exciting inductor current of the isolation transformer will only charge the resonant capacitor Cr1 through the reset winding Nt until the exciting inductor current i of the isolation transformer_LM(t) decays from Im to zero.

In the exciting inductance current i_LMAfter (t) decays from Im to zero, the obtained reverse exciting inductor current will not necessarily be-Im, and will be determined according to the initial values of the two resonant capacitors Cr1 and Cr2, regardless of whether the resonant reset circuit controlled by the MOS transistor Q1 or the resonant reset circuit controlled by the MOS transistor Q2 operates. The method comprises the following specific steps:

1) assuming that the initial voltages of the two resonant capacitors Cr1 and Cr2 are zero, the obtained opposite-phase excitation inductance current is-Im/2;

2) when the resonance is reset in a steady state, the initial voltage of the resonance capacitor Cr1 is assumed to be zero, and the initial voltage of the resonance capacitor Cr2 is assumed to be a peak value, so that the obtained opposite-phase excitation inductance current is-Im, and vice versa.

3) And assuming that the initial voltages of the two resonant capacitors Cr1 and Cr2 are not zero, the obtained reverse excitation inductance current is determined by half of the total energy after all the energies are superposed.

Note that: when the primary side MOS tube Q of the isolation transformer is conducted, if Np is equal to Nt, the dotted end of the reset winding Nt outputs corresponding input voltage V_INThe input voltage is added to the drains of MOS transistors Q1 and Q2 through a resonant capacitor Cr1 or Cr2, and the maximum voltage V borne between the drains and the sources of MOS transistors Q1 and Q2_DSMAXIs an input voltage V_INAdded with peak voltage V of resonant capacitor Cr1 or Cr2_{CR_PEAK}Namely: v_DSMAX＝V_IN+V_{CR_PEAK}. When the primary side MOS tube Q of the isolation transformer is cut off, the dotted terminal of the reset winding Nt outputs the resonance voltage change of the corresponding resonance capacitor Cr1 or Cr 2. The output voltage of the same name terminal of the reset winding Nt can be used to control when the MOS transistor Q1 or Q2 is turned on and off. The functional module M detects that the input terminal of the dotted terminal of the reset winding Nt is FB, and when the resonant voltage of the resonant capacitor Cr1 or Cr2 reaches the peak value, that is, the input terminal FB of the functional module M reaches the lowest valley value, it means that the body diode current of the MOS transistor Q1 or Q2 is zero. When the sum of the total body diode currents of the MOS tubes Q1 and Q2 is zero, the functional module M controls the MOS tube Q1 or Q2 to be conducted, the resonant capacitor Cr1 or Cr2 continues to resonate with the excitation inductor through the MOS tube Q1 or Q2 and the reset winding Nt until the voltage on the resonant capacitor Cr1 or Cr2 is zero and the sum is zeroThe parallel diode Dr1 or Dr2 is rendered conductive, the reset winding Nt voltage is zero, i.e. the voltage is zero; the FB voltage at the input end of the functional module M is zero, and the inductive current i is excited_LMAnd (t) finishing reverse, and finishing resonance reset by the isolation transformer. Since the MOS transistor Q1 or Q2 continues to be turned on, the voltage of the reset winding Nt is zero, and the voltage of the input terminal FB of the functional module M is continuously zero. Until the next switching period begins, the functional module M controls the MOS transistor Q1 or Q2 to be switched off according to the internal system logic circuit, and the reverse exciting inductive current i_LM(t) input of power supply V via primary winding Np_INAnd feeding back energy and enabling a primary side MOS tube Q of the isolation transformer to be switched on under the ZVS switching condition. In the next switching period, the functional module M controls the MOS transistor Q2 or Q1 to be conducted, the resonant capacitor Cr2 or Cr1 is resonated with the exciting inductor through the MOS transistor Q2 or Q1 and the reset winding Nt until the voltage on the resonant capacitor Cr2 or Cr1 is zero to enable the diode Dr2 or Dr1 connected in parallel to be conducted, and the voltage on the reset winding Nt is zero; exciting inductor current i_LMAnd (t) finishing reverse, and finishing resonance reset by the isolation transformer. Therefore, the MOS tubes Q1 and Q2 are conducted alternately in adjacent switching periods to complete the resonant reset of the isolation transformer, and the MOS tube Q on the primary side of the isolation transformer can be conducted and cut off under the ZVS switching condition. So that the forward converter operates with high efficiency switching.

As shown in fig. 5, when the input voltage fluctuates or the output power increases, the conduction time of the primary MOS of the isolation transformer increases suddenly, resulting in an exciting inductor current i_LM(t) suddenly increasing to Im + Δ, resetting the resonant reset circuit controlled by Q1 in the current switching period, and resetting the resonant reset circuit controlled by Q2 in the next switching period, so that the amplitude of the obtained reverse exciting inductor current is rapidly reduced; this exciting inductive current i_LM(t) a sudden increase, which will cause the peak voltages of Cr1 and Cr2 to increase, i.e. Cr1 or Cr2 increases from the original peak voltage to a new peak value; cr2 or Cr1 increased from zero voltage to a new peak voltage. Thus, the energy corresponding to the newly added excitation inductor current Im + Δ is absorbed by the two resonant capacitors Cr1 and Cr2, respectively, so that the energy added to each of the two resonant capacitors Cr1 and Cr2 is smaller than the energy added to one resonant capacitor Cr shown in fig. 1, and is absorbed by the resonant capacitor CThe magnitude of the reverse excitation inductor current value resulting from the new peak voltage of r1 or Cr2 will be less than Im + Δ. Therefore, the resonance resetting is controlled alternately by the MOS tubes Q1 and Q2, and the instantaneous values of the exciting inductance current at the turn-off time of the primary side MOS tube Q of the adjacent switching periods can be adjusted to be basically the same rapidly without any adjusting loop.

In the present invention, if the resonant reset circuit is implemented on the secondary side of the isolation transformer, a functional module M1 is added on the primary side of the isolation transformer to receive the isolation driving pulse transmitted from the secondary side of the isolation transformer through the coupling pulse transformer or two coupling capacitors to control the conduction of the primary side MOS transistor Q.

The resonant reset circuit of embodiment 3, corresponding to fig. 3, is completed at the secondary side of the isolation transformer, as shown in fig. 6. The method comprises the following specific steps:

the differences with respect to example 1 are:

the operation principle of the resonance reset in fig. 6 is completely the same as that in fig. 3, only the secondary side of the isolation transformer controls the resonance reset, so that the conduction cutoff of the primary side MOS transistor Q of the isolation transformer needs to be isolated and transmitted by the functional module M on the secondary side of the isolation transformer through the driving pulse transmitted by the coupling pulse transformer or the two coupling capacitors, the functional module M1 requires the conduction cutoff of the primary side MOS transistor of the isolation transformer according to the output information of the functional module M received from the driving pulse transmitted by the coupling pulse transformer or the two coupling capacitors, and the functional module M1 outputs a DR driving pulse to control the output of the primary side MOS transistor Q of the isolation transformer to be switched on and off by the ZVS switch according to the feedback voltage of the detection resistor Rs.

That is, according to the comparison of fig. 6 and fig. 3, example 3 differs from example 1 in that:

the output information of the functional module M is coupled to the functional module M1 through a coupling pulse transformer or two high-voltage small capacitors C1 and C2 in an isolation mode; the functional module M1 has a corresponding port to receive the output information of the functional module M transmitted via a pulse transformer isolation coupling or two high-voltage small capacitors C1 and C2 isolation coupling.

A pin DR of the functional module M1 is connected with a grid electrode of a primary side MOS tube Q of the output isolation transformer; the source of the primary side MOS transistor Q is connected to the detection resistor Rs and the pin Ss of the functional module M1.

The working process is characterized in that: the resonance reset control is carried out on the secondary side of the isolation transformer to ensure that the isolation transformer can effectively perform resonance reset, and the primary side MOS tube Q of the isolation transformer is switched on and off by a ZVS switch.

Embodiment 4, the resonance reset circuit corresponding to fig. 4 is completed at the secondary side of the isolation transformer, as shown in fig. 7:

the differences with respect to example 2 are:

the operation principle of the resonance reset in fig. 7 is completely the same as that in fig. 4, only the secondary side of the isolation transformer controls the resonance reset, so that the conduction cutoff of the primary side MOS transistor Q of the isolation transformer needs to be isolated and transmitted by the functional module M on the secondary side of the isolation transformer through the driving pulse transmitted by the coupling pulse transformer or the two coupling capacitors, the functional module M1 requires the conduction cutoff of the primary side MOS transistor of the isolation transformer according to the output information of the functional module M received from the driving pulse transmitted by the coupling pulse transformer or the two coupling capacitors, and the functional module M1 outputs a DR driving pulse to control the output of the primary side MOS transistor Q of the isolation transformer to be switched on and off by the ZVS switch according to the feedback voltage of the detection resistor Rs.

That is, according to the comparison of fig. 7 and fig. 4, example 4 differs from example 2 in that:

the output information of the functional module M is coupled to the functional module M1 through a coupling pulse transformer or two high-voltage small capacitors C1 and C2 in an isolation mode; the functional module M1 has a corresponding port to receive the output information of the functional module M transmitted via a pulse transformer isolation coupling or two high-voltage small capacitors C1 and C2 isolation coupling.

A pin DR of the functional module M1 is connected with a grid electrode of a primary side MOS tube Q of the output isolation transformer; the source of the primary side MOS transistor Q is connected to the detection resistor Rs and the pin Ss of the functional module M1.

The working process is characterized in that: the resonance reset control is carried out on the secondary side of the isolation transformer to ensure that the isolation transformer can effectively perform resonance reset, and the primary side MOS tube Q of the isolation transformer is switched on and off by a ZVS switch.

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.