阅读说明：本技术 一种开关电源的磁隔离反馈装置、方法和开关电源 (Magnetic isolation feedback device and method of switching power supply and switching power supply ) 是由 李通 谭章德 张敏 刘旭龙 郑培杰 于 2020-04-20 设计创作，主要内容包括：本发明公开了一种开关电源的磁隔离反馈装置、方法和开关电源,该装置包括：采样模块,用于采样开关电源的输出端的输出电压；输出控制模块,用于对采样得到的开关电源的输出端的输出电压进行脉冲化处理,得到脉冲信号；耦合模块,用于将脉冲化处理后的脉冲信号转化为脉冲沿信号后,将脉冲沿信号反馈至开关电源的输入端的输入控制模块,以实现开关电源的输入端的输入控制模块的输出与开关电源的输出端的输出控制模块同步。本发明的方案,可以解决在开关电源的输入端和输出端之间采用光耦实现隔离和信号反馈影响开关电源的稳定性和使用寿命的问题,达到提升开关电源的稳定性和使用寿命的效果。(The invention discloses a magnetic isolation feedback device and method of a switching power supply and the switching power supply, the device comprises: the sampling module is used for sampling the output voltage of the output end of the switching power supply; the output control module is used for carrying out pulse processing on the output voltage of the output end of the sampled switching power supply to obtain a pulse signal; and the coupling module is used for converting the pulse signal after the pulse processing into a pulse edge signal and feeding the pulse edge signal back to the input control module at the input end of the switching power supply so as to realize the synchronization of the output of the input control module at the input end of the switching power supply and the output control module at the output end of the switching power supply. According to the scheme provided by the invention, the problem that the stability and the service life of the switching power supply are influenced by realizing isolation and signal feedback by adopting the optical coupler between the input end and the output end of the switching power supply can be solved, and the effects of improving the stability and the service life of the switching power supply are achieved.)

1. A magnetically isolated feedback arrangement for a switching power supply, comprising: the device comprises a sampling module, an output control module and a coupling module; wherein the content of the first and second substances,

the sampling module is used for sampling the output voltage of the output end of the switching power supply;

the output control module is used for carrying out pulse processing on the output voltage of the output end of the sampled switching power supply to obtain a pulse signal;

and the coupling module is used for converting the pulse signal after the pulse processing into a pulse edge signal and feeding the pulse edge signal back to the input control module at the input end of the switching power supply so as to realize the synchronization of the output of the input control module at the input end of the switching power supply and the output control module at the output end of the switching power supply.

2. The magnetically isolated feedback arrangement of a switching power supply according to claim 1, wherein the sampling module comprises: the first voltage division module and the second voltage division module;

the first voltage division module and the second voltage division module are arranged between the output end of the switching power supply and the ground in series, and the common end of the first voltage division module and the common end of the second voltage division module are connected to the feedback end of the output control module.

3. The magnetically isolated feedback apparatus of claim 1 or 2, wherein the output control module comprises: a first DC/DC control chip.

4. The magnetically isolated feedback apparatus of claim 3, wherein the output control module further comprises: the first output capacitor, the second output capacitor and the first output resistor; wherein the content of the first and second substances,

the first output capacitor is connected between the COMP end of the first DC/DC control chip and the common ends of the first voltage division module and the second voltage division module; the second output capacitor is connected between the RT/CT end of the first DC/DC control chip and the ground; and the first output resistor is connected between the UREF end of the first DC/DC control chip and the RT/CT end of the first DC/DC control chip.

5. The magnetically isolated feedback arrangement of a switching power supply according to claim 3, wherein the coupling module comprises: the pulse transformer, the first resistor, the second resistor and the first capacitor; wherein the content of the first and second substances,

the homonymous terminal of the primary side of the pulse transformer is connected to the OUT terminal of the first DC/DC control chip through a first capacitor and a second capacitor, and the heteronymous terminal of the primary side of the pulse transformer is connected to a power ground;

and the secondary side of the pulse transformer is connected with the second resistor in parallel and then is connected to the input control module of the input end of the switching power supply.

6. A switching power supply, comprising: the output end of the magnetic isolation feedback circuit is connected to the input end of the power main loop; the magnetic isolation feedback circuit is the magnetic isolation feedback device of the switching power supply according to any one of claims 1 to 5.

7. A magnetic isolation feedback method of a switching power supply is characterized by comprising the following steps:

sampling the output voltage of the output end of the switching power supply through a sampling module;

through an output control module, pulse processing is carried out on the output voltage of the output end of the sampled switching power supply to obtain a pulse signal;

through the coupling module, after the pulse signal after the pulse processing is converted into the pulse edge signal, the pulse edge signal is fed back to the input control module of the input end of the switching power supply, so that the output of the input control module of the input end of the switching power supply is synchronous with the output control module of the output end of the switching power supply.

Technical Field

The invention belongs to the technical field of power supplies, and particularly relates to a magnetic isolation feedback device and method of a switching power supply and the switching power supply, in particular to a magnetic isolation feedback circuit of the switching power supply, the switching power supply with the magnetic isolation feedback circuit and a magnetic isolation feedback method of the switching power supply.

Background

Switching power supplies have taken an important position in electronic engineering and its products by virtue of their small size and high efficiency. In the application of the switching power supply, in order to reduce conducted interference in a power supply system of the switching power supply, it is often required that an input terminal and an output terminal of the switching power supply are isolated from each other.

For the input end and the output end of the switching power supply are isolated from each other, the traditional method is to use the optical coupler to realize isolation and signal feedback, but the current transfer coefficient of the optical coupler can gradually decrease along with the increase of working time due to the use of the light-emitting diode, so that the voltage regulation rate and the load regulation rate are reduced, and the stability and the service life of the whole switching power supply are influenced. The voltage regulation rate is an influence of a change in input voltage on a change in output voltage, and the load regulation rate is an influence of a change in load on a change in output voltage.

The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.

Disclosure of Invention

The invention aims to provide a magnetic isolation feedback device and method of a switching power supply and the switching power supply, aiming at overcoming the problem that the stability and the service life of the switching power supply are influenced by isolation and signal feedback between the input end and the output end of the switching power supply by adopting an optical coupler, and achieving the effects of improving the stability and the service life of the switching power supply.

The invention provides a magnetic isolation feedback device of a switching power supply, which comprises: the device comprises a sampling module, an output control module and a coupling module; the sampling module is used for sampling the output voltage of the output end of the switching power supply; the output control module is used for carrying out pulse processing on the output voltage of the output end of the sampled switching power supply to obtain a pulse signal; and the coupling module is used for converting the pulse signal after the pulse processing into a pulse edge signal and feeding the pulse edge signal back to the input control module at the input end of the switching power supply so as to realize the synchronization of the output of the input control module at the input end of the switching power supply and the output control module at the output end of the switching power supply.

Optionally, the sampling module comprises: the first voltage division module and the second voltage division module; the first voltage division module and the second voltage division module are arranged between the output end of the switching power supply and the ground in series, and the common end of the first voltage division module and the common end of the second voltage division module are connected to the feedback end of the output control module.

Optionally, the output control module comprises: a first DC/DC control chip.

Optionally, the output control module further includes: the first output capacitor, the second output capacitor and the first output resistor; the first output capacitor is connected between the COMP end of the first DC/DC control chip and the common ends of the first voltage division module and the second voltage division module; the second output capacitor is connected between the RT/CT end of the first DC/DC control chip and the ground; and the first output resistor is connected between the UREF end of the first DC/DC control chip and the RT/CT end of the first DC/DC control chip.

Optionally, a coupling module comprising: the pulse transformer, the first resistor, the second resistor and the first capacitor; the homonymous terminal of the primary side of the pulse transformer is connected to the OUT terminal of the first DC/DC control chip through a first capacitor and a second capacitor, and the heteronymous terminal of the primary side of the pulse transformer is connected to a power ground; and the secondary side of the pulse transformer is connected with the second resistor in parallel and then is connected to the input control module of the input end of the switching power supply.

In accordance with another aspect of the present invention, there is provided a switching power supply, including: the output end of the magnetic isolation feedback circuit is connected to the input end of the power main loop; the magnetic isolation feedback circuit is specifically the magnetic isolation feedback device of the switching power supply.

In another aspect, the present invention provides a magnetic isolation feedback method for a switching power supply, including: sampling the output voltage of the output end of the switching power supply through a sampling module; through an output control module, pulse processing is carried out on the output voltage of the output end of the sampled switching power supply to obtain a pulse signal; through the coupling module, after the pulse signal after the pulse processing is converted into the pulse edge signal, the pulse edge signal is fed back to the input control module of the input end of the switching power supply, so that the output of the input control module of the input end of the switching power supply is synchronous with the output control module of the output end of the switching power supply.

According to the scheme, the output voltage of the switching power supply is sampled and subjected to pulse processing, and then the output voltage is coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the problems that the current transfer coefficient is reduced along with the increase of working time, the voltage and load regulation rate is reduced, and the stability and the service life are reduced in an optical isolation scheme can be solved, and the stability, the reliability and the service life of the switching power supply can be effectively improved.

Furthermore, according to the scheme of the invention, the output voltage of the switching power supply is sampled and subjected to pulse processing, and then is coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the problems of complexity and large volume of a magnetic isolation feedback circuit can be solved, and the volume of the magnetic isolation type switching power supply is reduced.

Furthermore, according to the scheme of the invention, a pulse width signal modulated according to an error signal can be obtained by directly inputting a voltage signal obtained by sampling into a DC/DC control chip by using the DC/DC control chip, then the pulse signal is converted into a pulse edge signal by a pulse edge transmission circuit and can be directly sent to another DC/DC control chip at the input end, so that the DC/DC control chip at the input end is synchronous with the pulse edge signal, the output pulse width of the DC/DC control chip at the input end is adjusted to achieve the purpose of stabilizing the voltage, the stability of the switching power supply is improved, and the service life of the switching power supply is prolonged.

Therefore, according to the scheme provided by the invention, the output voltage of the switching power supply is sampled and subjected to pulse processing, and then coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the problem that the stability and the service life of the switching power supply are influenced by realizing isolation and signal feedback by adopting an optical coupler between the input end and the output end of the switching power supply is solved, and the effects of improving the stability and the service life of the switching power supply are achieved.

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

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

Fig. 1 is a schematic structural diagram of a magnetic isolation feedback device of a switching power supply according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a switching power supply according to an embodiment of the present invention, specifically, a schematic structural diagram of a switching power supply using a novel magnetic isolation feedback;

fig. 3 is a flowchart illustrating a magnetic isolation feedback method of a switching power supply according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In consideration of the fact that the stability and the service life of the switching power supply are influenced by the fact that the optical coupler is adopted between the input end and the output end of the switching power supply to achieve isolation and signal feedback, other isolation feedback modes such as magnetic isolation are mostly adopted in application occasions with high requirements on the stability, the reliability and the service life of the switching power supply. Among them, the superior high temperature performance, long life and wide band of magnetic isolation make it a staple of high reliability application. However, since the magnetic isolation requires error amplification and modulation of the voltage obtained by sampling the output, and demodulation is required after the voltage reaches the input side, the circuit is complicated, and the circuit volume is increased.

For example: other ways of isolating feedback may include: magnetic isolation feedback and high-voltage isolation chip (such as capacitive isolation) feedback, which are the most commonly used isolation methods, plus optical coupling isolation. The specific isolation method of magnetic isolation is to use a transformer or a coupled inductor for isolation.

Therefore, the scheme of the invention provides a simple magnetic isolation feedback circuit (namely, a switching power supply which uses a simple magnetic isolation scheme and has a small volume), so that the problems that the current transfer coefficient of the optical isolation scheme is reduced along with the increase of the working time, the voltage and load regulation rate is reduced, and the stability and the service life are reduced can be solved, and the stability, the reliability and the service life of the switching power supply can be effectively improved; the problems of complex circuit and large volume of magnetic isolation feedback can be solved, and the volume of the magnetic isolation type switch power supply is reduced.

According to an embodiment of the present invention, there is provided a magnetically isolated feedback arrangement for a switching power supply. Referring to fig. 1, a schematic diagram of an embodiment of the apparatus of the present invention is shown. The magnetic isolation feedback device, namely the magnetic isolation feedback loop, of the switching power supply can comprise: the input end of the switch power supply is provided with an input control module.

In particular, the sampling module may be configured to sample an output voltage at an output terminal of the switching power supply.

Optionally, the sampling module comprises: the device comprises a first voltage division module and a second voltage division module. For example: the first voltage dividing module may be a resistor R1. And the second voltage division module can be a resistor R2. The first voltage division module and the second voltage division module are arranged between the output end of the switching power supply and the ground in series, and the common end of the first voltage division module and the common end of the second voltage division module are connected to the feedback end of the output control module.

From this, through first voltage division module and second voltage division module to the output voltage of switching power supply output end sample, simple structure, and can guarantee that the sampling result is accurate.

Specifically, the output control module may be configured to perform pulse processing on the output voltage of the output end of the sampled switching power supply to obtain a pulse signal.

Optionally, the output control module may include: a first DC/DC control chip, such as DC/DC control chip U2.

For example: the feedback circuit is simplified by using a DC/DC control chip (e.g., a first DC/DC control chip) at the output of the switching power supply to process the output sampled voltage. And then after the output of the DC/DC control chip (such as the first DC/DC control chip) at the output end of the switching power supply is subjected to pulse processing, the output of the DC/DC control chip (such as the second DC/DC control chip) at the input end of the switching power supply is coupled to the DC/DC control chip (such as the second DC/DC control chip) at the input end of the switching power supply through a pulse transformer, so that the output of the DC/DC control chip (such as the second DC/DC control chip) at the input end of the switching power supply is synchronous with the output of the DC/DC controller (such as the first DC/DC control chip). And the isolation feedback adopts a pulse edge transmission circuit, so that the volume of the isolation transformer can be reduced.

Therefore, the output voltage of the switching power supply is subjected to pulse processing by sampling the first DC/DC control chip, the structure is simple, and the pulse processing result is reliable.

More optionally, the output control module may further include: the circuit comprises a first output capacitor, a second output capacitor and a first output resistor.

The first output capacitor is connected between the COMP end of the first DC/DC control chip and a common end of the first voltage division module and the second voltage division module. And the second output capacitor is connected between the RT/CT end of the first DC/DC control chip and the ground. And the first output resistor is connected between the UREF end of the first DC/DC control chip and the RT/CT end of the first DC/DC control chip.

Therefore, the first output capacitor, the second output capacitor, the first output resistor and the like are used as peripheral circuits of the first DC/DC control chip, and the processing effect of the first DC/DC control chip on the pulse processing of the switching power supply can be improved.

Specifically, the coupling module may be configured to convert the pulse signal after the pulse processing into a pulse edge signal, and then feed back the pulse edge signal to the input control module at the input end of the switching power supply, so as to synchronize the output of the input control module at the input end of the switching power supply with the output control module at the output end of the switching power supply.

For example: by using a second DC/DC control chip (e.g., a first DC/DC control chip), the sampled voltage signal is directly input to the chip (e.g., the first DC/DC control chip), then the pulse width signal modulated according to the error signal can be obtained, then the pulse signal is converted into pulse edge signal by means of pulse edge transmission circuit, a DC/DC control chip, such as a second DC/DC control chip, may be fed directly to the input, synchronizing the input control chip with the pulse edge signal, therefore, the purpose of stabilizing the voltage is achieved by adjusting the output pulse width of the input end chip, the problems that the current transfer coefficient is reduced along with the increase of the working time, the voltage and load regulation rate is reduced, the stability and the service life are reduced in an optical isolation scheme can be solved, and the stability, the reliability and the service life of the switching power supply can be effectively improved. And need not introduce outside high frequency carrier, the circuit is succinct, compact structure, can solve the complicated and great problem of volume of circuit of magnetic isolation feedback, reduces the volume of magnetic isolation formula switching power supply.

Therefore, after the output voltage of the switching power supply is sampled and subjected to pulse processing, the output voltage is coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the output pulse width of the input end chip is adjusted, the voltage stability is improved, the stability of the switching power supply is improved, and the service life of the switching power supply is prolonged.

Optionally, the coupling module, i.e. the pulse transmission circuit, comprises: pulse transformer, first resistance, second resistance and first electric capacity. For example: the pulse transformer may be a transformer T2, the first resistor may be a resistor R3, the second resistor may be a resistor R4, and the first capacitor may be a capacitor C2.

The dotted terminal of the primary side of the pulse transformer is connected to the OUT terminal of the first DC/DC control chip through the first capacitor and the second capacitor, and the dotted terminal of the primary side of the pulse transformer is connected to the power ground. And the secondary side of the pulse transformer is connected with the second resistor in parallel and then is connected to the input control module of the input end of the switching power supply. An input control module comprising: and a second DC/DC control chip.

For example: a magnetically isolated feedback loop, which may include: the sampling resistors R1 and R2, the output end DC/DC control chip U2 (such as the first DC/DC control chip) and the peripheral circuit thereof, the pulse transformer T2 and R3, R4 and C2 which form a pulse transmission circuit together with the T2. The input end DC/DC control chip needs to have the functions of starting by using an input voltage, receiving an external pulse signal and synchronously driving the switching tube. The output end DC/DC chip only needs to have the function of adjusting the pulse width of the output signal according to the feedback.

Therefore, the pulse signal after the pulse processing is converted into the pulse edge signal and then fed back to the input control module of the input end of the switching power supply through the pulse transformer, the first resistor, the second resistor and the first capacitor, the structure is simple, and the processing effect can be guaranteed.

Through a large number of tests, the technical scheme of the invention is adopted, the output voltage of the switching power supply is sampled and subjected to pulse processing, and then the output voltage is coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the problems of current transfer coefficient reduction, voltage and load regulation rate reduction, stability and service life reduction of an optical isolation scheme along with the increase of working time can be solved, and the stability, reliability and service life of the switching power supply can be effectively improved.

According to an embodiment of the present invention, there is also provided a switching power supply corresponding to a magnetically isolated feedback arrangement of the switching power supply. The switching power supply may include: the magnetic isolation feedback circuit comprises a power supply main loop and a magnetic isolation feedback circuit, wherein the output end of the power supply main loop is connected to the input end of the magnetic isolation feedback circuit, and the output end of the magnetic isolation feedback circuit is connected to the input end of the power supply main loop. The magnetic isolation feedback circuit is specifically the magnetic isolation feedback device of the switching power supply.

Therefore, the stability of the switching power supply can be improved and the service life of the switching power supply can be prolonged through the matching arrangement of the main power supply loop and the magnetic isolation feedback circuit.

For example, as shown in fig. 2, the switching power supply using the magnetic isolation feedback circuit in the solution of the present invention may include a power supply main loop and a magnetic isolation feedback loop, the power supply main loop may mainly include a switching power supply input terminal DC/DC control chip U1 (such as the second DC/DC control chip described above) and its peripheral circuit, a field effect transistor Q1, a high frequency transformer T1, rectifier diodes D1 and D3, a freewheeling diode D2, an output inductor L1, an output capacitor c 1. the magnetic isolation feedback loop may include sampling resistors R1 and R2, an output terminal DC/DC control chip U2 (such as the first DC/DC control chip described above) and its peripheral circuit, a pulse transformer T2, and R3, R4, and C2. which together with T2 form a pulse transmission circuit, wherein the input terminal DC/DC control chip may need to have a function of starting using an input voltage, being capable of receiving an external pulse signal and synchronously driving the switching tube.

For example: the peripheral circuit can be a circuit necessary for meeting the normal working requirement of the chip; the resistor, the capacitor and the diode are used for meeting the normal work of the chip. The U2 peripheral circuits function identically to U1, and differ because they use different chips. The U1 needs to have the function of receiving the secondary pulse signal and synchronously driving the switch tube. The U2 may be implemented by using a general pulse width modulation chip, and may be configured to adjust the PWM output according to the sampling voltage.

Specifically, the power main loop comprises an input end control module of an input end of a switching power supply, a switching tube, a high-frequency transformer, a first rectifying diode, a second rectifying diode, a first freewheeling diode, an output inductor and an output capacitor, wherein the input end control module comprises a second DC/DC control chip, for example, the switching tube is a field effect transistor Q1, the high-frequency transformer is a transformer T1, the first rectifying diode is a rectifying diode D1, the second rectifying diode is a rectifying diode D3, the first freewheeling diode is a freewheeling diode D2, the output inductor is an inductor L1 and the output capacitor is a capacitor C1.

The homonymous terminal of the primary side of the first transformer in the high-frequency transformer is connected with a signal ground, and the synonym terminal of the primary side of the first transformer is connected to the power supply end of the second DC/DC control chip. The dotted terminal of the secondary side of the first transformer is connected to the anode of the first rectifying diode, then connected to the cathode of the first freewheeling diode, and connected to the input terminal of the magnetic isolation feedback circuit after passing through the output inductor. The first end of the output capacitor is connected to one end, far away from the first rectifying diode, of the output inductor, and the second end of the output capacitor is connected to the anode of the first freewheeling diode and the synonym end of the secondary side of the first transformer. The dotted terminal of the primary side of a second transformer in the high-frequency transformer is connected to the power supply end of a second DC/DC control chip, the synonym terminal of the primary side of the second transformer is connected to the drain electrode of the switching tube, and the grid electrode of the switching tube is connected to the output end of the second DC/DC control chip. The synonym end of the secondary side of the second transformer is connected with the anode of a second rectifier diode, and the cathode of the second rectifier diode is connected to the power supply end of an output control module in the magnetic isolation feedback circuit. The homonymous terminal of the secondary side of the second transformer is connected with the power ground. The FB terminal and the SS terminal of the second DC/DC control chip are connected to the output terminal of the magnetic isolation feedback circuit.

Further, the power main loop may further include: the first to fourth input resistors, the first input diode, and the first to fourth input capacitors.

The synonym end of the primary side of the first transformer is connected to the anode of the first input diode, and the cathode of the first input diode is connected to the power supply end of the second DC/DC control chip. The dotted terminal of the primary side of the second transformer is connected to the cathode of the first input diode through the first input resistor, and the anode of the first input diode is connected to the dotted terminal of the primary side of the first transformer. The first input capacitor is connected between the dotted terminal of the primary side of the second transformer and the ground terminal. The second input capacitor is connected between the power supply terminal of the second DC/DC control chip and the ground terminal of the second DC/DC control chip. The third input capacitor is connected between the reference terminal of the second DC/DC control chip and the CS terminal of the second DC/DC control chip. The second input resistor is connected between the reference terminal of the second DC/DC control chip and the RT terminal of the second DC/DC control chip. The first end of the third input resistor and the first end of the fourth input resistor are connected and connected to the source electrode of the switching tube, and the second end of the third input resistor is connected to the ground end of the second DC/DC control chip. The second end of the fourth input resistor is connected with the signal ground. The fourth input capacitor is connected between the second connection of the third input resistor and the signal ground.

The operating principle of the circuit shown in fig. 2 is: after the power supply is switched on, the input end DC/DC control chip U1 is started according to a set frequency, the output voltage of the circuit is established, and the output end DC/DC control chip U2 starts to work. The output voltage error signal is sampled by the voltage dividing and sampling resistors R1 and R2 and then is directly sent to the feedback terminal FB of the output terminal DC/DC control chip U2, so that the output pulse width of the output terminal DC/DC control chip U2 is modulated according to the sampling voltage, the output pulse width modulation signal is transmitted to the feedback pin of the input terminal DC/DC control chip U1 through a pulse transmission circuit formed by the resistor R3, the capacitor C2, the pulse transformer T2 and the resistor R4, the pulse width modulation signal output by the input terminal DC/DC control chip U1 is synchronous with the output terminal DC/DC control chip U2, the on-off time of the field effect transistor Q1 is adjusted, and the output voltage is stable.

For example: modulating its output pulse width according to the sampled voltage may include: a comparator is arranged in the chip, one pin of the comparator is connected with the sampling voltage, and the other pin of the comparator is connected with a standard voltage source in the chip; the sampling voltage should be the same as the standard voltage in theory, when the sampling voltage is greater than or less than the standard voltage, the comparator will output the corresponding output to the PWM wave generator inside the chip, and the PWM wave generator will adjust the pulse width of the PWM wave.

For example: adjusting the on-off time of the field effect transistor Q1 may include: u1 is also a PWM control chip (pulse width modulation chip), but U1 has a function of receiving a secondary pulse signal and synchronously driving the switching tubes. When the U1 receives the pulse signal fed back by the pulse transmission circuit (the pulse signal is modulated by the sampling voltage), the pulse width of the PWM wave is adjusted according to the pulse signal (i.e. the time of the PWM wave at high level and low level in one period is adjusted). The output PWM wave is connected with the control end of the switch tube, the switch tube is conducted when the PWM wave is at high level (or low level), and the conduction time of the switch tube is adjusted after the chip adjusts the time of high level and low level in a period (as for whether the switch tube is conducted at high level or low level, the conduction time is related to the characteristics of the switch tube and a specific circuit).

The pulse transformer T2 required in the scheme of the invention can be small in volume, and the circuit is very simple, so that the problems that the stability of a system is reduced when the optical coupling isolation is used for long-time work, and the traditional magnetic isolation circuit is complex and too large in volume are solved.

For example: since the signal transmitted in the pulse transmission circuit is a modulated pulse signal, the frequency of the signal is high, and the current thereof is small because it is the transmitted signal. And the volume of the transformer is related to the frequency and magnitude of the current flowing through the transformer. The larger the frequency of the current flowing through the transformer and the smaller the current, the smaller the volume of the transformer can be made.

Since the processing and functions implemented by the switching power supply of this embodiment substantially correspond to the embodiments, principles, and examples of the foregoing devices, reference may be made to the related descriptions in the foregoing embodiments without being detailed in the description of this embodiment.

Through a large number of tests, the technical scheme of the invention is adopted, and the output voltage of the switching power supply is sampled and subjected to pulse processing and then coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the problems of complexity and large volume of a magnetic isolation feedback circuit can be solved, and the volume of the magnetic isolation type switching power supply is reduced.

According to an embodiment of the present invention, there is also provided a magnetic isolation feedback method for a switching power supply corresponding to the switching power supply, as shown in fig. 3, which is a schematic flow chart of an embodiment of the method of the present invention. The magnetic isolation feedback method of the switching power supply can comprise the following steps: step S110 to step S130.

At step S110, an output voltage of an output terminal of the switching power supply is sampled by the sampling module.

In step S120, the sampled output voltage of the output terminal of the switching power supply is subjected to pulse processing by the output control module, so as to obtain a pulse signal.

In step S130, after the pulse signal after the pulse processing is converted into a pulse edge signal by the coupling module, the pulse edge signal is fed back to the input control module of the input terminal of the switching power supply, so as to synchronize the output of the input control module of the input terminal of the switching power supply with the output control module of the output terminal of the switching power supply.

For example: by using a second DC/DC control chip (e.g., a first DC/DC control chip), the sampled voltage signal is directly input to the chip (e.g., the first DC/DC control chip), then the pulse width signal modulated according to the error signal can be obtained, then the pulse signal is converted into pulse edge signal by means of pulse edge transmission circuit, a DC/DC control chip, such as a second DC/DC control chip, may be fed directly to the input, synchronizing the input control chip with the pulse edge signal, therefore, the output pulse width of the input end chip is adjusted to achieve the purpose of stabilizing the voltage, the problems that the current transfer coefficient of an optical isolation scheme is reduced along with the increase of working time, the voltage and load regulation rate is reduced, and the stability and the service life are reduced can be solved, and the stability, the reliability and the service life of the switching power supply can be effectively improved; and need not introduce outside high frequency carrier, the circuit is succinct, compact structure, can solve the complicated and great problem of volume of circuit of magnetic isolation feedback, reduces the volume of magnetic isolation formula switching power supply.

Therefore, after the output voltage of the switching power supply is sampled and subjected to pulse processing, the output voltage is coupled to the input end of the switching power supply, so that the output voltage of the input end of the switching power supply is synchronous with the sampling voltage of the output end of the switching power supply, the output pulse width of the input end chip is adjusted, the voltage stability is improved, the stability of the switching power supply is improved, and the service life of the switching power supply is prolonged.

Since the processing and functions implemented by the method of this embodiment substantially correspond to the embodiments, principles, and examples of the switching power supply, reference may be made to the related descriptions in the foregoing embodiments without being detailed in the description of this embodiment.

Through a large number of tests, the technical scheme of the embodiment is adopted, a DC/DC control chip is used, a voltage signal obtained by sampling is directly input into the DC/DC control chip, a pulse width signal modulated according to an error signal can be obtained, then the pulse signal is converted into a pulse edge signal through a pulse edge transmission circuit, and the pulse edge signal can be directly sent to another DC/DC control chip at the input end, so that the DC/DC control chip at the input end is synchronous with the pulse edge signal, the output pulse width of the DC/DC control chip at the input end is adjusted to achieve the purpose of stabilizing the voltage, the stability of the switching power supply is improved, and the service life of the switching power supply is prolonged.

In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.

The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.