CN109742931B - A power isolation feedback method and circuit - Google Patents

Abstract

The invention discloses a power supply isolation feedback method and a circuit, comprising the following steps: s1, performing partial pressure sampling on an input voltage signal to obtain a voltage sampling signal; s2, synthesizing the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal; s3, converting the first voltage signal into an ultrasonic signal, and converting the ultrasonic signal into a second voltage signal after passing through an insulating medium; s4, rectifying and filtering the second voltage signal to obtain a response voltage signal; and S5, performing closed-loop control on the response voltage signal to obtain an output voltage signal. Due to the adoption of the technical scheme, compared with the prior art, the invention utilizes the characteristic that ultrasonic energy passes through liquid or solid insulating medium to achieve the purpose of improving isolation voltage; the high isolation voltage class can be achieved, the manufacturing cost is low, and the transmitted feedback voltage signals are safe and reliable.

Description

A power isolation feedback method and circuit

Technical field

The invention relates to the technical field of voltage sampling electrical isolation, and in particular to a power isolation feedback method and circuit.

Background technique

At present, in the field of high-voltage power supply applications, multiple power supplies are usually used in series to superimpose the output to achieve the purpose of outputting high voltage. In order to improve the stability of the system, each power module itself needs to perform feedback closed-loop regulation of its own output voltage. However, the voltage between the output terminals of different power modules and the input grid will increase as the number of series power supplies increases. As shown in Figure 1, it is a schematic diagram of the series output of multi-module isolated power supplies. The positive and negative poles of the output terminals of power module 1 and power module N are connected end to end. In order to ensure the stability of the output voltage of each module, a voltage isolation feedback loop must be used for closed-loop control. As the number of module stages increases, the isolation voltage capability of the voltage isolation feedback circuit of the corresponding stage is required to be higher and higher.

The commonly used isolation voltage feedback methods include: optical coupling device isolation feedback, transformer isolation feedback, optical fiber isolation feedback and Hall voltage sensor. Optocoupled isolation feedback, the device withstand voltage value is low, the highest is only a few thousand volts, and there is a shift in the operating point. The insulation of the transformer isolation feedback skeleton is insufficient, the manufacturing process is complex, the volume is large, and the efficiency is low. It can only be applied to AC output voltage. Optical fiber isolation feedback effect is good, the voltage level is high, it requires modulation and demodulation circuit, and the cost is high. Hall voltage sensors also have requirements that cannot meet the isolation voltage level. Therefore, there is an urgent need to develop an isolation feedback circuit that not only has high isolation voltage and insulation level, but also has low manufacturing cost.

Contents of the invention

In order to solve the problem in the background art that the existing power supply isolation feedback circuit cannot have both low cost and high isolation voltage level, the present invention provides a power supply isolation feedback method. The specific technical solution is as follows.

A power isolation feedback method, the method includes the following steps:

S1. Voltage sampling, divide and sample the input voltage signal to obtain the voltage sampling signal;

S2. Amplitude modulation, synthesize the voltage sampling signal and the constant amplitude carrier signal to obtain the first voltage signal;

S3. Ultrasonic transmission, converting the first voltage signal into an ultrasonic signal, and then converting the ultrasonic signal into a second voltage signal after passing through the insulating medium;

S4. Signal restoration, rectifying and filtering the second voltage signal to obtain a response voltage signal;

S5. Closed-loop control: perform closed-loop control on the response voltage signal to obtain an output voltage signal.

In the above method, the input voltage signal is the output voltage of the isolated feedback power module. The amplitude modulation (synthesizing the voltage sampling signal and the constant amplitude carrier signal) refers to multiplying the voltage sampling signal and the constant amplitude carrier signal. The constant amplitude carrier signal may be a unidirectional square wave, a bidirectional square wave or a sine wave.

First, the output voltage of the power module that needs feedback is divided and sampled to obtain a voltage sampling signal; in order to make the voltage sampling signal reach the driving frequency of the ultrasonic transmission unit, the voltage sampling signal is synthesized with a constant amplitude carrier signal to obtain The ultrasonic transmission unit drives a first voltage signal with the same frequency; utilizing the characteristics of ultrasonic waves that can pass through liquid or solid insulating media, the first voltage signal is converted into an ultrasonic signal. After the ultrasonic signal passes through the insulating medium, it is converted as the second voltage signal to achieve the purpose of isolating the voltage; then through signal restoration and closed-loop control, the output voltage signal is finally obtained. The circuits used to realize amplitude modulation, signal restoration, and closed-loop control are all existing technologies, and the present invention does not make any improvements to these circuits themselves. This solution uses the characteristic that ultrasonic waves can pass through liquid or solid insulating media to achieve the purpose of increasing the isolation voltage; it utilizes the wide linear area between the transmitting ultrasonic device and the receiving ultrasonic device, and the voltage amplitude in the linear area is transmitted to achieve different Linear feedback of voltage between potentiometric circuits. Not only can a high isolation voltage level be achieved, but the manufacturing cost is low, and the transmitted feedback voltage signal is safe and reliable.

Preferably, the following step is further included between S2 and S3: power amplification, performing power amplification processing on the first voltage signal so that it can drive the ultrasonic transmission unit.

In order to make the first voltage signal reach the rated power for driving the ultrasonic transmission unit, the first voltage signal is subjected to power amplification processing so that it can drive the ultrasonic transmission unit.

Preferably, the step between S1 and S2 is as follows: applying a first reference voltage based on the voltage sampling signal; and the step between S4 and S5 is as follows: applying the first reference voltage on the basis of the response voltage signal. A second reference voltage is applied to .

The second reference power supply has the same polarity as the first reference power supply, and an inverting amplifier input is used to perform subtraction operations; or the second reference power supply and the first reference source have opposite polarities, and a non-inverting amplifier input is used to perform addition operations. In order to satisfy the better linear transmission voltage of the ultrasonic device and avoid the range where the small signal response is not sensitive enough and the linearity is not good, the first reference signal (V1) is applied to give the voltage signal an offset, so that the ultrasonic device works in a sensitive range. linear operating range. After the ultrasonic transmission is completed, in order to restore the signal (eliminate the previous offset), the second reference voltage is applied in the reverse direction (V1 can be applied in the reverse direction, or -V1 can be applied in the same direction). In this way, the final output voltage The size of the signal is proportional to the voltage sampling signal.

Preferably, the following step is further included between S3 and S4: impedance matching, performing impedance matching processing on the ultrasonic receiving device.

By performing impedance matching processing on the ultrasonic receiving device, the second voltage signal is made more stable in the entire range.

Based on the same inventive concept, the present invention also provides a power isolation feedback circuit, including:

A voltage sampling unit is used to divide and sample the output voltage of the isolated feedback power module to obtain a voltage sampling signal;

Constant amplitude carrier signal generator, used to generate constant amplitude carrier signals;

An amplitude modulation unit, used to synthesize the voltage sampling signal and the constant amplitude carrier signal to obtain a first voltage signal;

Ultrasonic transmission unit, the ultrasonic transmission unit includes an ultrasonic transmitting device, an ultrasonic receiving device and an insulating medium located between the two; the ultrasonic transmitting device is used to receive the first voltage signal and convert it into an ultrasonic signal; The ultrasonic receiving device is used to receive the ultrasonic signal and convert it into a second voltage signal;

a signal reduction unit, used to rectify and filter the second voltage signal to obtain a response voltage signal;

A control unit configured to perform closed-loop control on the response voltage signal to obtain an output voltage signal;

The output end of the voltage sampling unit is connected to the first input end of the amplitude modulation unit, and the output end of the constant amplitude carrier signal generator is connected to the second input end of the amplitude modulation unit; the amplitude modulation unit The output end of the ultrasonic wave transmitting device is connected to the input end of the ultrasonic wave receiving device, the output end of the ultrasonic wave receiving device is connected to the input end of the signal reduction unit, and the output end of the signal reduction unit is connected to the input end of the control unit. .

In the above circuit, the input voltage signal is the output voltage of the power module that is isolated and fed back. The amplitude modulation unit uses a multiplier to multiply the voltage sampling signal and the constant amplitude carrier signal. The constant amplitude carrier signal may be a unidirectional square wave, a bidirectional square wave or a sine wave. The signal restoration unit is composed of a rectifier circuit and a filter circuit. The rectifier circuit may be a bridge rectifier circuit, and the filter circuit is composed of an inductor and a capacitor.

First, the voltage sampling unit performs voltage dividing sampling on the output voltage of the power module that needs feedback to obtain a voltage sampling signal; in order to make the voltage sampling signal reach the driving frequency of the ultrasonic transmission unit, the voltage sampling unit is used to sample the voltage through the amplitude modulation unit. The signal is synthesized with the constant-amplitude carrier signal generated by the constant-amplitude carrier signal generator to obtain a first voltage signal consistent with the driving frequency of the ultrasonic transmission unit; utilizing the characteristics of ultrasonic waves that can penetrate liquid or solid insulating media, the ultrasonic wave passes through the ultrasonic transmission unit The first voltage signal is converted into an ultrasonic signal. After the ultrasonic signal passes through the insulating medium, it is converted into a second voltage signal to achieve the purpose of isolating the voltage; then the signal is restored through the signal restoration unit, and finally through The control unit performs closed-loop control and finally obtains the output voltage signal. The circuits used in the amplitude modulation unit, signal restoration unit and closed-loop control unit are all existing technologies, and the present invention does not make any improvements to these circuits themselves. This solution uses the characteristic that ultrasonic waves can pass through liquid or solid insulating media to achieve the purpose of increasing the isolation voltage; it utilizes the wide linear area between the transmitting ultrasonic device and the receiving ultrasonic device, and the voltage amplitude is transmitted in the linear area to achieve Linear feedback of voltage between circuits of different potentials. Not only can a high isolation voltage level be achieved, but the manufacturing cost is low, and the transmitted feedback voltage signal is safe and reliable.

Preferably, a power amplification unit is further provided between the amplitude modulation unit and the ultrasonic transmitting device, and the power amplifying unit is used to perform power amplification processing on the first voltage signal to drive the ultrasonic transmitting device. The input end of the power amplification unit is connected to the output end of the amplitude modulation unit, and the output end of the power amplification unit is connected to the input end of the ultrasonic transmitting device.

In order to make the first voltage signal reach the rated power for driving the ultrasonic transmission unit, the first voltage signal is subjected to power amplification processing through a power amplification unit so that it can drive the ultrasonic transmission unit.

Preferably, a first amplifier and a first reference power supply are further provided between the voltage sampling unit and the amplitude modulation unit, and the first input terminal of the first amplifier is connected to the output terminal of the voltage sampling unit, so The second input terminal of the first amplifier is connected to the output terminal of the first reference power supply, and the output terminal of the first amplifier is connected to the input terminal of the amplitude modulation unit;

A second amplifier and a second reference power supply are also provided between the signal restoration unit and the control unit. The first input terminal of the second amplifier is connected to the output terminal of the signal restoration unit. The second amplifier The second input terminal is connected to the output terminal of the second reference power supply, and the output terminal of the second amplifier is connected to the input terminal of the control unit.

In order to satisfy the better linear transmission voltage of the ultrasonic device and avoid the interval where the small signal response is not sensitive enough and the linearity is not good, the first amplifier and the first reference power supply are used to apply a first voltage on the basis of the voltage sampling signal. The reference signal (V1) gives an offset to the voltage signal, allowing the ultrasonic device to operate in a sensitive linear operating range. After the ultrasonic transmission is completed, in order to restore the signal (eliminate the previous offset), the second reference voltage is applied in the reverse direction through the second amplifier and the second reference power supply (V1 can be applied in the reverse direction, or - in the same direction) V1), that is, applying a second reference voltage based on the response signal, so that the size of the final output voltage signal is proportional to the voltage sampling signal.

Preferably, an impedance matching unit is further provided between the ultrasonic receiving device and the reduction unit, and the impedance matching unit is used to perform impedance matching processing on the ultrasonic receiving device. The input end of the impedance matching unit is connected to the output end of the ultrasonic receiving device, and the output end of the impedance matching unit is connected to the input end of the signal restoration unit.

By performing impedance matching processing on the ultrasonic receiving device, the second voltage signal is made more stable in the entire range. The impedance matching unit is an existing technology, and the present invention does not make any improvements to this circuit.

Preferably, the amplitude modulation unit is a multiplier.

Preferably, both the first amplifier and the second amplifier are operational amplifiers.

Due to the adoption of the above technical solution, compared with the existing technology, the present invention utilizes the characteristics of ultrasonic waves that can pass through liquid or solid insulating media to achieve the purpose of increasing the isolation voltage; it utilizes the wide gap between the transmitting ultrasonic device and the receiving ultrasonic device. In the linear region, the voltage amplitude is transmitted in the linear region to realize linear feedback of voltage between circuits with different potentials. Not only can a high isolation voltage level be achieved, but the manufacturing cost is low, and the transmitted feedback voltage signal is safe and reliable. The invention can easily feed back the output voltage samples of power modules with different levels of potential to the front-end converter to control the stability of the voltage. The size of the insulation voltage is determined by changing the type and distance of the insulation material. It is very convenient and has a wide linear working area. Small size and low cost.

Description of the drawings

Figure 1 is a flow chart of the power supply isolation feedback method of the present invention;

Figure 2 is a schematic diagram of the circuit structure of Embodiment 2 of the present invention;

Figure 3 is a schematic diagram of the circuit structure of Embodiment 3 of the present invention;

Figure 4 is a schematic structural diagram of the ultrasonic receiving and transmitting device of the present invention;

Figure 5 is a schematic diagram of the relationship between the excitation voltage and the response voltage between the ultrasonic transmitting and receiving devices of the present invention;

Figure 6 is a schematic diagram of the circuit structure of Embodiment 4 of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Example 1

Referring to Figure 1, a power isolation feedback method includes the following steps:

S1. Perform voltage dividing and sampling on the input voltage signal to obtain the voltage sampling signal;

S2. Apply reference voltage 1 based on the voltage sampling signal;

S3. Synthesize the voltage sampling signal and the constant amplitude carrier signal to obtain the first voltage signal;

S4. Convert the first voltage signal into an ultrasonic signal, and then convert the ultrasonic signal into a second voltage signal after passing through the insulating medium;

S5. Perform impedance matching, rectification and filtering on the second voltage signal to obtain a response voltage signal;

S6. Apply reference voltage 2 based on the response voltage signal;

S7. Perform closed-loop control on the response voltage signal to obtain the final output voltage signal.

Example 2

See Figure 2 for a power supply isolation feedback circuit. include:

A voltage sampling unit, the voltage sampling unit includes a first resistor R1 and a second resistor R2, used for dividing and sampling the output voltage of the isolated feedback power module to obtain a voltage sampling signal;

A first amplifier (amplifier 1 in the figure) and a first reference power supply (reference power supply 1 in the figure). The first input end of the first amplifier is connected to the output end of the voltage sampling unit. The first amplifier The second input terminal is connected to the output terminal of the first reference power supply.

Amplitude modulation unit, the amplitude modulation unit is a multiplier, used to multiply the voltage sampling signal and the constant amplitude carrier signal to obtain a first voltage signal; the first input end of the multiplier and the Connect the output of the first amplifier.

A constant amplitude carrier signal generator, which is an active crystal oscillator, used to generate a square wave signal; the second input end of the multiplier is connected to the output end of the active crystal oscillator.

Power amplification unit, the power amplification unit is a power amplification circuit, used to perform power amplification processing on the first voltage signal to drive the ultrasonic transmitting device; the input end of the power amplification circuit and the input end of the multiplier Output connection.

Ultrasonic transmission unit, the ultrasonic transmission unit includes an ultrasonic transmitting device (an ultrasonic transmitting device in the figure), an ultrasonic receiving device (an ultrasonic receiving device in the figure), and an insulating medium (transformer oil in the figure) located between the two; The ultrasonic transmitting device is used to receive the first voltage signal and convert it into an ultrasonic signal; after the ultrasonic signal passes through the insulating medium, the ultrasonic receiving device receives the ultrasonic signal and converts it into a third Two voltage signals; the input end of the ultrasonic transmitting device is connected to the output end of the power amplifier circuit.

An impedance matching unit (an impedance matching circuit in the figure), the impedance matching unit is used to perform impedance matching processing on the second voltage signal, and the input end of the impedance matching unit is connected to the output end of the ultrasonic receiving device.

A signal restoration unit (precision rectifier circuit in the figure) is used to rectify and filter the second voltage signal to obtain a response voltage signal; the input terminal of the signal restoration unit is connected to the output terminal of the impedance matching unit.

A second amplifier (amplifier 2 in the figure) and a second reference power supply (reference power supply 2 in the figure). The first input end of the second amplifier is connected to the output end of the signal restoration unit. The second amplifier The second input terminal is connected to the output terminal of the second reference power supply.

A control unit (a control circuit in the figure) is used to perform closed-loop control on the response voltage signal to obtain a final output voltage signal; the input end of the control unit is connected to the output end of the second amplifier.

The insulating medium between the ultrasonic transmitting device and the ultrasonic receiving device is No. 25 transformer oil, and the distance between the ultrasonic transmitting device and the ultrasonic receiving device is 10 mm.

The first amplifier and the second amplifier both use a general operational amplifier LM358; the multiplier uses an AD734; the active crystal oscillator uses an active crystal oscillator with a frequency of 40kHz and a rated voltage of 5V, and the input to the multiplier is square. wave signal; the power amplifier circuit adopts LM386 power amplification integrated circuit; the ultrasonic transmitting device adopts 40T, and the ultrasonic receiving device adopts 40R; the control unit is an embedded system STM32, and the first reference power supply output voltage value is 1.0V, and the maximum excitation voltage amplitude can reach 20V. The output voltage value of the second reference power supply is -1.0V. With this design, the isolation voltage reaches more than 35KV.

Example 3

See Figure 3 for a power supply isolation feedback circuit. include:

A voltage sampling unit, the voltage sampling unit includes a first resistor R1 and a second resistor R2, used for dividing and sampling the output voltage of the isolated feedback power module to obtain a voltage sampling signal;

A first amplifier (amplifier 1 in the figure) and a first reference power supply (reference power supply 1 in the figure). The first input end of the first amplifier is connected to the output end of the voltage sampling unit. The first amplifier The second input terminal is connected to the output terminal of the first reference power supply.

Amplitude modulation unit, the amplitude modulation unit is a multiplier, used to multiply the voltage sampling signal and the constant amplitude carrier signal to obtain a first voltage signal; the first input end of the multiplier and the Connect the output of the first amplifier.

A constant amplitude carrier signal generator, which is a sine wave generator, used to generate a sine wave signal; the second input end of the multiplier is connected to the output end of the sine wave generator.

Power amplification unit, the power amplification unit is a power amplification circuit, used to perform power amplification processing on the first voltage signal to drive the ultrasonic transmitting device; the input end of the power amplification circuit and the input end of the multiplier Output connection.

Ultrasonic transmission unit, the ultrasonic transmission unit includes an ultrasonic transmitting device (an ultrasonic transmitting device in the figure), an ultrasonic receiving device (an ultrasonic receiving device in the figure), and an insulating medium (transformer oil in the figure) located between the two; The ultrasonic transmitting device is used to receive the first voltage signal and convert it into an ultrasonic signal; after the ultrasonic signal passes through the insulating medium, the ultrasonic receiving device receives the ultrasonic signal and converts it into a third Two voltage signals; the input end of the ultrasonic transmitting device is connected to the output end of the power amplifier circuit.

An impedance matching unit (an impedance matching circuit in the figure), the impedance matching unit is used to perform impedance matching processing on the ultrasonic receiving device, and the input end of the impedance matching unit is connected to the output end of the ultrasonic receiving device.

A signal restoration unit (precision rectifier circuit in the figure) is used to rectify and filter the second voltage signal to obtain a response voltage signal; the input terminal of the signal restoration unit is connected to the output terminal of the impedance matching unit.

A second amplifier (amplifier 2 in the figure) and a second reference power supply (reference power supply 2 in the figure). The first input end of the second amplifier is connected to the output end of the signal restoration unit. The second amplifier The second input terminal is connected to the output terminal of the second reference power supply.

A control unit (a control circuit in the figure) is used to perform closed-loop control on the response voltage signal to obtain a final output voltage signal; the input end of the control unit is connected to the output end of the second amplifier.

The insulating medium between the ultrasonic transmitting device and the ultrasonic receiving device is tetrafluoroethylene, and the distance between the ultrasonic transmitting device and the ultrasonic receiving device is 3 mm.

The first amplifier and the second amplifier both use high-performance operational amplifier OPA2227; the multiplier uses AD633; the frequency of the sine wave generator is 40kHz, and the input to multiplier 3 is a sine wave; the power amplifier The circuit uses TDA2030 power amplifier integrated circuit; the ultrasonic transmitter uses 40T, and the ultrasonic receiving device uses 40R; the control unit is a pulse width modulation control chip SG3525, and the output voltage value of the first reference power supply is between 0.5V -1.2V, with this design, the isolation voltage reaches more than 35KV.

Figure 4 is a schematic structural diagram of the ultrasonic receiving and transmitting device. The transmitting ultrasonic device and the receiving ultrasonic device are installed opposite the insulating medium. The insulating medium can be liquid, solid or gas with good insulating properties such as transformer oil, tetrafluoroethylene, epoxy resin, sulfur hexafluoride, etc. The isolation voltage depends on the insulation properties of the insulating material and the distance between the two ultrasonic devices.

Under the action of ultrasonic waves, the receiving ultrasonic device causes mechanical oscillation and outputs an electrical signal with a frequency of 40KHz, which is then connected to the impedance matching circuit and then into the precision rectifier circuit. Here, the 40KHz carrier frequency signal has been filtered out, leaving only the unipolar outer envelope voltage signal of the modulated carrier signal. At the same time, in order to restore the reference power supply 1 applied to amplifier 1, a reference power supply 2 is applied to amplifier 2. . In this way, the voltage signal output by amplifier 2 is proportional to the sampling voltage obtained by the voltage dividing resistors R1 and R2. Finally, it is sent to the control circuit, and after algorithm processing, the control signal is output to the converter to complete the entire closed-loop control and ultimately achieve stable high-voltage output.

The relationship between the excitation voltage and the response voltage between the ultrasonic transmitting and receiving devices is shown in Figure 5. Since ultrasonic devices usually have a vibration threshold, the second curve in Figure 6 is selected to work. The threshold voltage can be set through the reference power supply 1.

Example 4

See Figure 6 for a power supply isolation feedback circuit. The entire feedback circuit is divided into 12 parts. The first part is the voltage sampling circuit, consisting of R1 and R2, which completes the voltage sampling of the power module. Vin_H and Vin_L are the high and low terminals of the feedback power module output respectively; the second part is the first amplifier, consisting of resistors R3, R4, R5, R6 It is composed of the operational amplifier LM358-1, and the circuit structure is an adder circuit; the third part is the first reference voltage, which is composed of resistors R7, R8, R9 and the reference voltage source TL431-1. The fourth part is the 40KHz square wave generator circuit, which is implemented by active crystal oscillator Y1 and capacitor C1. The fifth part is the amplitude modulation synthesis circuit, which is implemented by the multiplier AD734. The first signal is differentially input between X1 and X2 and comes from the output of the first amplifier. The second signal is differentially input between Y1 and Y2 and comes from the active crystal oscillator. The output signal of Y1. The sixth part is the power amplifier circuit, which is composed of the integrated power amplifier circuit LM386 and the capacitor C2. The signal comes from C1 and is input by the third pin of LM386; the seventh part is the ultrasonic transmitting and receiving circuit, which consists of the transmitting end P1 and the receiving end P2. And isolating dielectric transformer oil composition. The eighth part is the impedance matching circuit, which is composed of inductor L1 and capacitor C3. The ninth part is a precision rectification and filtering circuit, which consists of resistors R10, R11, R12, R13, R14, R15, R16, operational amplifiers LM358-2, LM358-3, and diodes D1 and D2. C4 completes the filtering function. The tenth part is the second amplifier, which is composed of R17, R18, R19 and operational amplifier LM358-4. The circuit structure is a subtraction circuit. The eleventh part is the second reference voltage, which is composed of resistors R20, R21, R22 and reference voltage source TL431-2. The twelfth part is the control circuit, which is implemented by STM32 small system.

The following table shows the differences between the main parameters of the present invention and the prior art:

As can be seen from the above table, the optocoupler device feedback method has low isolation voltage level, small linear range, low cost, and can only feed back DC voltage; the transformer feedback method is large and heavy, has a high isolation voltage level, but can only feed back AC voltage, and The cost is high, and the voltage linearity is also small when the signal is small; the Hall voltage sensor feedback voltage level is low, the cost is also high, and the linearity range is small. The method used in the present invention can have a very high isolation voltage level, a small volume, good linearity in the full range of small voltages and large voltages, and low cost, and is also suitable for feedback of AC and DC voltages. Compared with the first three, it can not only overcome their respective shortcomings, but also possess their respective advantages, and the overall performance is very excellent.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be used Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent substitutions are made to some of the technical features; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (4)

1. A power isolation feedback method, the method includes the following steps: S1. Perform voltage dividing and sampling on the input voltage signal to obtain the voltage sampling signal; S2. Apply the first reference voltage based on the voltage sampling signal; S3. Synthesize the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal, and perform power amplification processing on the first voltage signal so that it can drive the ultrasonic transmission unit; S4. Convert the first voltage signal into an ultrasonic signal. After the ultrasonic signal passes through the insulating medium, it is converted into a second voltage signal; S5. Perform impedance matching, rectification and filtering on the second voltage signal to obtain a response voltage signal; S6. Apply a second reference voltage based on the response voltage signal; S7. Perform closed-loop control on the response voltage signal to obtain an output voltage signal. 2. A power isolation feedback circuit, characterized by including: A voltage sampling unit, including a first resistor and a second resistor, is used to divide and sample the output voltage of the isolated feedback power module to obtain a voltage sampling signal; Constant amplitude carrier signal generator, used to generate constant amplitude carrier signals; An amplitude modulation unit, used to synthesize the voltage sampling signal and the constant amplitude carrier signal to obtain a first voltage signal; Ultrasonic transmission unit, the ultrasonic transmission unit includes an ultrasonic transmitting device, an ultrasonic receiving device and an insulating medium located between the two; the ultrasonic transmitting device is used to receive the first voltage signal and convert it into an ultrasonic signal; The ultrasonic receiving device is used to receive the ultrasonic signal and convert it into a second voltage signal; A power amplification unit, located between the amplitude modulation unit and the ultrasonic transmitting device, is used to perform power amplification processing on the first voltage signal to drive the ultrasonic transmitting device; a signal reduction unit, used to rectify and filter the second voltage signal to obtain a response voltage signal; A control unit configured to perform closed-loop control on the response voltage signal to obtain an output voltage signal; A first amplifier and a first reference power supply are further provided between the voltage sampling unit and the amplitude modulation unit. The first input end of the first amplifier is connected to the output end of the voltage sampling unit. The first The second input terminal of the amplifier is connected to the output terminal of the first reference power supply, and the output terminal of the first amplifier is connected to the first input terminal of the amplitude modulation unit; A second amplifier and a second reference power supply are also provided between the signal restoration unit and the control unit. The first input terminal of the second amplifier is connected to the output terminal of the signal restoration unit. The second amplifier The second input terminal is connected to the output terminal of the second reference power supply, and the output terminal of the second amplifier is connected to the input terminal of the control unit; An impedance matching unit is also provided between the ultrasonic receiving device and the reduction unit, and the impedance matching unit is used to perform impedance matching processing on the ultrasonic receiving device; The output end of the constant amplitude carrier signal generator is connected to the second input end of the amplitude modulation unit; the output end of the amplitude modulation unit is connected to the input end of the ultrasonic transmitting device, and the output of the ultrasonic receiving device The terminal is connected to the input terminal of the signal restoration unit. 3. The power supply isolation feedback circuit according to claim 2, wherein the amplitude modulation unit is a multiplier. 4. The power supply isolation feedback circuit according to claim 2 or 3, characterized in that: the first amplifier and the second amplifier are both operational amplifiers.