CN109742931B - Power supply isolation feedback method and circuit - Google Patents
Power supply isolation feedback method and circuit Download PDFInfo
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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
Technical Field
The invention relates to the technical field of voltage sampling electrical isolation, in particular to a power supply isolation feedback method and a circuit.
Background
At present, in the field of high-voltage power application, a plurality of power supplies are commonly used for series superposition output, so as to achieve the purpose of outputting high voltage. In order to improve the stability of the system, each power module needs to perform feedback closed-loop regulation on the output voltage of the power module. However, the voltage between the output terminals of the different power supply modules and the input power grid increases with the number of series power supplies. As shown in fig. 1, a schematic diagram of a multi-module isolated power supply series output is shown. The positive pole and the negative pole of the output end of power module 1 and power module N end to end, in order to guarantee the stability of every module output voltage, must use voltage isolation feedback loop to carry out 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 existing common method for feeding back the isolation voltage comprises the following steps: the optical coupling device comprises an optical coupling device isolation feedback, a transformer isolation feedback, an optical fiber isolation feedback and a Hall voltage sensor. The optical coupling isolation feedback has low voltage withstand value of the device, which is only a few kilovolts at most, and the working point is deviated. The isolation feedback framework of the transformer has the defects of insufficient insulativity, complex process manufacturing, large volume, low efficiency and the like, and can only be applied to the condition of alternating current output voltage. The optical fiber isolation feedback effect is good, the voltage level is high, a modulation and demodulation circuit is needed, and the cost is high. Hall voltage sensors also have the requirement that they cannot reach an isolated voltage level. Therefore, there is a need to develop an isolation feedback circuit with high isolation voltage insulation level and low manufacturing cost.
Disclosure of Invention
In order to solve the problem that the existing power supply isolation feedback circuit in the background technology cannot have low cost and high isolation voltage level, the invention provides a power supply isolation feedback method, and the specific technical scheme is as follows.
A power isolation feedback method, the method comprising the steps of:
s1, voltage sampling, namely performing partial pressure sampling on an input voltage signal to obtain a voltage sampling signal;
s2, amplitude modulation, namely synthesizing the voltage sampling signal and a constant-amplitude carrier signal to obtain a first voltage signal;
s3, ultrasonic transmission is carried out, the first voltage signal is converted into an ultrasonic signal, and the ultrasonic signal passes through an insulating medium and is then converted into a second voltage signal;
s4, signal reduction, namely rectifying and filtering the second voltage signal to obtain a response voltage signal;
s5, performing closed-loop control on the response voltage signal to obtain an output voltage signal.
In the above method, the input voltage signal is an output voltage of the power module that is fed back in an isolated manner. The amplitude modulation (combining the voltage sample signal with the constant amplitude carrier signal) refers to multiplying the voltage sample signal with the constant amplitude carrier signal. The constant amplitude carrier signal can be a unidirectional square wave, or a bidirectional square wave or a sinusoidal wave.
Firstly, carrying out partial pressure sampling on the output voltage of a power module needing feedback to obtain a voltage sampling signal; in order to enable the voltage sampling signal to reach the driving frequency for driving the ultrasonic transmission unit, synthesizing the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal consistent with the driving frequency of the ultrasonic transmission unit; the characteristic that ultrasonic energy passes through liquid or solid insulating medium is utilized to convert the first voltage signal into an ultrasonic signal, and the ultrasonic signal passes through the insulating medium and then is converted into a second voltage signal so as to achieve the purpose of voltage isolation; and then, finally obtaining an output voltage signal through signal reduction and closed-loop control. The circuits used for realizing amplitude modulation, signal restoration and closed-loop control are all the prior art, and the invention does not make any improvement on the circuits per se. The scheme utilizes the characteristic that ultrasonic energy passes through liquid or solid insulating medium to achieve the purpose of improving isolation voltage; the linear feedback of the voltage between different potential circuits is realized by using a wider linear region between the transmitting ultrasonic device and the receiving ultrasonic device and transmitting the voltage amplitude in the linear region. The high isolation voltage class can be achieved, the manufacturing cost is low, and the transmitted feedback voltage signals are safe and reliable.
Preferably, the steps between S2 and S3 further include: and power amplification is carried out on the first voltage signal, so that the first voltage signal 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 as to drive the ultrasonic transmission unit.
Preferably, the steps between S1 and S2 further include: applying a first reference voltage on the basis of the voltage sampling signal; the steps between S4 and S5 also comprise the following steps: a second reference voltage is applied on the basis of the response voltage signal.
The second reference power supply has the same polarity as the first reference power supply, and performs subtraction operation using an inverting amplifier input, or performs addition operation using an in-phase amplifier input with the second reference power supply having opposite polarity to the first reference source. In order to meet the better linear transmission voltage of the ultrasonic device, a section with insensitive tiny signal response and poor linearity is avoided, and the voltage signal is given an offset by applying a first reference signal (V1), so that the ultrasonic device works in a sensitive linear working range. After the ultrasonic transmission is completed, in order to restore the signal (to eliminate the previous offset), a second reference voltage is applied in the opposite direction (V1 may be applied in the opposite direction or-V1 may be applied in the same direction), so that the magnitude of the finally output voltage signal is proportional to the voltage sampling signal.
Preferably, the steps between S3 and S4 further include: and performing impedance matching, namely performing impedance matching treatment on the ultrasonic receiving device.
By performing impedance matching processing on the ultrasonic receiving device, the second voltage signal is more stable in the whole range.
Based on the same inventive concept, the invention also provides a power isolation feedback circuit, comprising:
the voltage sampling unit is used for carrying out partial pressure sampling on the output voltage of the power module which is fed back in an isolated mode to obtain a voltage sampling signal;
the constant amplitude carrier signal generator is used for generating constant amplitude carrier signals;
the amplitude modulation unit is used for synthesizing the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal;
the ultrasonic transmission unit comprises an ultrasonic transmitting device, an ultrasonic receiving device and an insulating medium positioned between the ultrasonic transmitting device and the ultrasonic receiving device; the ultrasonic wave transmitting device is used for receiving the first voltage signal and converting the first voltage signal into an ultrasonic wave signal; the ultrasonic receiving device is used for receiving the ultrasonic signal and converting the ultrasonic signal into a second voltage signal;
the signal recovery unit is used for rectifying and filtering the second voltage signal to obtain a response voltage signal;
the control unit is used for performing closed-loop control on the response voltage signal to obtain an output voltage signal;
the output end of the voltage sampling unit is connected with the first input end of the amplitude modulation unit, and the output end of the constant-amplitude carrier signal generator is connected with the second input end of the amplitude modulation unit; the output end of the amplitude modulation unit is connected with the input end of the ultrasonic wave transmitting device, the output end of the ultrasonic wave receiving device is connected with the input end of the signal restoring unit, and the output end of the signal restoring unit is connected with the input end of the control unit.
In the circuit, the input voltage signal is the output voltage of the power module which is fed back in an isolated mode. The amplitude modulation unit adopts a multiplier to multiply the voltage sampling signal with a constant amplitude carrier signal. The constant amplitude carrier signal can be a unidirectional square wave, or a bidirectional square wave or a sinusoidal wave. The signal recovery unit is composed of a rectifying circuit and a filtering circuit, wherein the rectifying circuit can be a bridge rectifying circuit, and the filtering circuit is composed of an inductor and a capacitor.
Firstly, the voltage sampling unit is used for carrying out partial pressure sampling on the output voltage of the power module needing feedback to obtain a voltage sampling signal; in order to enable the voltage sampling signal to reach the driving frequency for driving the ultrasonic transmission unit, the amplitude modulation unit synthesizes the voltage sampling signal and 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; the characteristic that ultrasonic energy passes through liquid or solid insulating medium is utilized, the first voltage signal is converted into an ultrasonic signal through an ultrasonic transmission unit, and the ultrasonic signal passes through the insulating medium and is then converted into a second voltage signal, so that the purpose of voltage isolation is achieved; and then, carrying out signal reduction through a signal reduction unit, and finally, carrying out closed-loop control through a control unit to finally obtain an output voltage signal. The circuits used by the amplitude modulation unit, the signal reduction unit and the closed-loop control unit are all the prior art, and the invention does not make any improvement on the circuits. The scheme utilizes the characteristic that ultrasonic energy passes through liquid or solid insulating medium to achieve the purpose of improving the isolation voltage; the linear feedback of the voltage between different potential circuits is realized by using a wider linear region between the transmitting ultrasonic device and the receiving ultrasonic device and transmitting the voltage amplitude in the linear region. The high isolation voltage class can be achieved, the manufacturing cost is low, and the transmitted feedback voltage signals are safe and reliable.
Preferably, a power amplifying unit is further arranged between the amplitude modulation unit and the ultrasonic transmitting device, and the power amplifying unit is used for performing power amplifying processing on the first voltage signal so as to drive the ultrasonic transmitting device. The input end of the power amplification unit is connected with the output end of the amplitude modulation unit, and the output end of the power amplification unit is connected with the input end of the ultrasonic wave transmitting device.
In order to make the first voltage signal reach the rated power for driving the ultrasonic transmission unit, the power amplification unit is used for carrying out power amplification treatment on the first voltage signal so as to enable the first voltage signal to drive the ultrasonic transmission unit.
Preferably, a first amplifier and a first reference power supply are further arranged between the voltage sampling unit and the amplitude modulation unit, a first input end of the first amplifier is connected with an output end of the voltage sampling unit, a second input end of the first amplifier is connected with an output end of the first reference power supply, and an output end of the first amplifier is connected with an input end of the amplitude modulation unit;
the signal recovery unit is characterized in that a second amplifier and a second reference power supply are further arranged between the signal recovery unit and the control unit, a first input end of the second amplifier is connected with an output end of the signal recovery unit, a second input end of the second amplifier is connected with an output end of the second reference power supply, and an output end of the second amplifier is connected with an input end of the control unit.
In order to meet the better linear transmission voltage of the ultrasonic device, a section with insensitive tiny signal reaction and poor linearity is avoided, a first reference signal (V1) is applied on the basis of the voltage sampling signal through the first amplifier and the first reference power supply, and an offset is given to the voltage signal, so that the ultrasonic device works in a sensitive linear working range. After the ultrasonic transmission is completed, in order to restore the signal (eliminate the previous offset), a second reference voltage is applied in a reverse direction (V1 may be applied in a reverse direction or-V1 may be applied in the same direction) through the second amplifier and the second reference power supply, that is, the second reference voltage is applied on the basis of the response signal, so that the magnitude of the finally output voltage signal is proportional to the voltage sampling signal.
Preferably, an impedance matching unit is further arranged between the ultrasonic receiving device and the restoring unit, and the impedance matching unit is used for performing impedance matching processing on the ultrasonic receiving device. The input end of the impedance matching unit is connected with the output end of the ultrasonic receiving device, and the output end of the impedance matching unit is connected with the input end of the signal restoring unit.
By performing impedance matching processing on the ultrasonic receiving device, the second voltage signal is more stable in the whole range. The impedance matching unit is prior art and the invention does not make any improvement to the circuit.
Preferably, the amplitude modulation unit is a multiplier.
Preferably, the first amplifier and the second amplifier are both operational amplifiers.
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 linear feedback of the voltage between different potential circuits is realized by using a wider linear region between the transmitting ultrasonic device and the receiving ultrasonic device and transmitting the voltage amplitude in the linear region. The high isolation voltage class can be achieved, the manufacturing cost is low, and the transmitted feedback voltage signals are safe and reliable. The invention can conveniently feed back the output voltage samples of the power supply modules with different level potentials to the pre-stage converter, control the voltage stabilization, determine the insulation voltage by changing the type and the distance of the insulation material, and has the advantages of convenience, wide whole volume of the linear working area, and low cost.
Drawings
FIG. 1 is a flow chart of a power isolation feedback method of the present invention;
fig. 2 is a schematic circuit diagram of embodiment 2 of the present invention;
fig. 3 is a schematic circuit diagram of embodiment 3 of the present invention;
FIG. 4 is a schematic diagram of the structure of an ultrasonic receiving and transmitting device of the present invention;
FIG. 5 is a schematic diagram showing the relationship between excitation voltage and response voltage between ultrasonic transmitting and receiving devices according to the present invention;
fig. 6 is a schematic circuit diagram of embodiment 4 of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
Example 1
Referring to fig. 1, a power isolation feedback method includes the steps of:
s1, performing partial pressure sampling on an input voltage signal to obtain a voltage sampling signal;
s2, applying a reference voltage 1 on the basis of the voltage sampling signal;
s3, synthesizing the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal;
s4, converting the first voltage signal into an ultrasonic signal, and converting the ultrasonic signal into a second voltage signal after the ultrasonic signal passes through an insulating medium;
s5, performing impedance matching, rectification and filtering on the second voltage signal to obtain a response voltage signal;
s6, applying a reference voltage 2 on the basis of the response voltage signal;
and S7, performing closed-loop control on the response voltage signal to obtain a final output voltage signal.
Example 2
Referring to fig. 2, a power isolation feedback circuit. Comprising the following steps:
the voltage sampling unit comprises a first resistor R1 and a second resistor R2 and is used for carrying out partial pressure sampling on the output voltage of the power module which is fed back in an isolated mode to obtain a voltage sampling signal;
the voltage sampling device comprises a first amplifier (an amplifier 1 in the figure) and a first reference power supply (the reference power supply 1 in the figure), wherein a first input end of the first amplifier is connected with an output end of the voltage sampling unit, and a second input end of the first amplifier is connected with an output end of the first reference power supply.
The amplitude modulation unit is a multiplier and is used for multiplying the voltage sampling signal and the constant amplitude carrier signal to obtain a first voltage signal; the first input of the multiplier is connected to the output of the first amplifier.
The constant amplitude carrier signal generator is an active crystal oscillator and is used for generating square wave signals; and the second input end of the multiplier is connected with the output end of the active crystal oscillator.
The power amplification unit is a power amplification circuit and is used for carrying out power amplification treatment on the first voltage signal so as to drive the ultrasonic wave transmitting device; the input end of the power amplifying circuit is connected with the output end of the multiplier.
The ultrasonic transmission unit comprises an ultrasonic transmission device (an ultrasonic transmission device in the figure), an ultrasonic receiving device (an ultrasonic receiving device in the figure) and an insulating medium (transformer oil in the figure) positioned between the ultrasonic transmission device and the ultrasonic receiving device; the ultrasonic wave transmitting device is used for receiving the first voltage signal and converting the first voltage signal into an ultrasonic wave signal; after the ultrasonic signal passes through the insulating medium, the ultrasonic receiving device receives the ultrasonic signal and converts the ultrasonic signal into a second voltage signal; the input end of the ultrasonic wave transmitting device is connected with the output end of the power amplifying circuit.
And the impedance matching unit (in the figure, an impedance matching circuit) is used for performing impedance matching processing on the second voltage signal, and the input end of the impedance matching unit is connected with the output end of the ultrasonic receiving device.
The signal recovery unit (a precise rectification circuit in the figure) is used for rectifying and filtering the second voltage signal to obtain a response voltage signal; the input end of the signal restoring unit is connected with the output end of the impedance matching unit.
The second amplifier (amplifier 2 in the figure) and the second reference power supply (reference power supply 2 in the figure), the first input end of the second amplifier is connected with the output end of the signal reduction unit, and the second input end of the second amplifier is connected with the output end of the second reference power supply.
The control unit (control circuit in the figure) is used for performing closed-loop control on the response voltage signal to obtain a final output voltage signal; the input end of the control unit is connected with the output end of the second amplifier.
The insulating medium between the ultrasonic wave transmitting device and the ultrasonic wave receiving device adopts No. 25 transformer oil, and the distance between the ultrasonic wave transmitting device and the ultrasonic wave receiving device is 10mm.
The first amplifier and the second amplifier both adopt a common operational amplifier LM358; the multiplier adopts AD734; the active crystal oscillator adopts an active crystal oscillator with the frequency of 40kHz and the rated voltage of 5V, and is input to the multiplier to be a square wave signal; the power amplifying circuit adopts an LM386 power amplifying integrated circuit; the ultrasonic wave transmitting device adopts 40T, and the ultrasonic wave receiving device adopts 40R; the control unit is an embedded system STM32, the output voltage value of the first reference power supply is 1.0V, and the maximum excitation voltage amplitude can reach 20V. The second reference power supply output voltage value is-1.0V. With the design, the isolation voltage reaches more than 35 KV.
Example 3
Referring to fig. 3, a power isolation feedback circuit. Comprising the following steps:
the voltage sampling unit comprises a first resistor R1 and a second resistor R2 and is used for carrying out partial pressure sampling on the output voltage of the power module which is fed back in an isolated mode to obtain a voltage sampling signal;
the voltage sampling device comprises a first amplifier (an amplifier 1 in the figure) and a first reference power supply (the reference power supply 1 in the figure), wherein a first input end of the first amplifier is connected with an output end of the voltage sampling unit, and a second input end of the first amplifier is connected with an output end of the first reference power supply.
The amplitude modulation unit is a multiplier and is used for multiplying the voltage sampling signal and the constant amplitude carrier signal to obtain a first voltage signal; the first input of the multiplier is connected to the output of the first amplifier.
The constant amplitude carrier signal generator is a sine wave generator and is used for generating sine wave signals; and the second input end of the multiplier is connected with the output end of the sine wave generator.
The power amplification unit is a power amplification circuit and is used for carrying out power amplification treatment on the first voltage signal so as to drive the ultrasonic wave transmitting device; the input end of the power amplifying circuit is connected with the output end of the multiplier.
The ultrasonic transmission unit comprises an ultrasonic transmission device (an ultrasonic transmission device in the figure), an ultrasonic receiving device (an ultrasonic receiving device in the figure) and an insulating medium (transformer oil in the figure) positioned between the ultrasonic transmission device and the ultrasonic receiving device; the ultrasonic wave transmitting device is used for receiving the first voltage signal and converting the first voltage signal into an ultrasonic wave signal; after the ultrasonic signal passes through the insulating medium, the ultrasonic receiving device receives the ultrasonic signal and converts the ultrasonic signal into a second voltage signal; the input end of the ultrasonic wave transmitting device is connected with the output end of the power amplifying circuit.
And the impedance matching unit (in the figure, an impedance matching circuit) is used for carrying out impedance matching treatment on the ultrasonic receiving device, and the input end of the impedance matching unit is connected with the output end of the ultrasonic receiving device.
The signal recovery unit (a precise rectification circuit in the figure) is used for rectifying and filtering the second voltage signal to obtain a response voltage signal; the input end of the signal restoring unit is connected with the output end of the impedance matching unit.
The second amplifier (amplifier 2 in the figure) and the second reference power supply (reference power supply 2 in the figure), the first input end of the second amplifier is connected with the output end of the signal reduction unit, and the second input end of the second amplifier is connected with the output end of the second reference power supply.
The control unit (control circuit in the figure) is used for performing closed-loop control on the response voltage signal to obtain a final output voltage signal; the input end of the control unit is connected with the output end of the second amplifier.
The insulating medium between the ultrasonic wave transmitting device and the ultrasonic wave receiving device adopts tetrafluoroethylene, and the distance between the ultrasonic wave transmitting device and the ultrasonic wave receiving device is 3mm.
The first amplifier and the second amplifier both adopt a high-performance operational amplifier OPA2227; the multiplier adopts AD633; the frequency of the sine wave generator is 40kHz, and the sine wave generator is input to the multiplier 3 to form sine waves; the power amplifying circuit adopts a TDA2030 power amplifying integrated circuit; the ultrasonic wave transmitting device adopts 40T, and the ultrasonic wave receiving device adopts 40R; the control unit is a pulse width modulation control chip SG3525, the output voltage value of the first reference power supply is between 0.5V and 1.2V, and the isolation voltage is more than 35 KV.
Fig. 4 is a schematic structural view of an ultrasonic receiving and transmitting device. The ultrasonic transmitting device and the ultrasonic receiving device are arranged opposite to an insulating medium, and the insulating medium can be liquid, solid or gas with good insulating performance, such as transformer oil, tetrafluoroethylene, epoxy resin, sulfur hexafluoride and the like. The magnitude of the isolation voltage depends on the insulating properties of the insulating material and the distance of the two ultrasonic devices.
Under the action of ultrasonic wave, the receiving ultrasonic device causes mechanical oscillation, outputs an electric signal with the frequency of 40KHz, is connected to the impedance matching circuit, and then enters the precise rectifying circuit. The 40KHz carrier frequency signal has been filtered out, leaving only the unipolar envelope voltage signal modulating the carrier signal, while a reference power supply 2 is applied to the amplifier 2 in order to restore the reference power supply 1 applied to the amplifier 1. The magnitude of the voltage signal output from the amplifier 2 is thus proportional to the sampled voltage obtained by the voltage dividing resistors R1 and R2. And finally, sending the power supply to a control circuit, and outputting a control signal to the converter after algorithm processing, so that the whole closed-loop control is finished, and finally, the high-voltage output stability is realized.
The relationship between the excitation voltage and the response voltage between the ultrasonic transmitting and receiving devices is shown in fig. 5. Since the ultrasonic device generally has a vibration threshold, the 2 nd curve in fig. 6 is selected to operate, and the threshold voltage can be set by the reference power supply 1.
Example 4
Referring to fig. 6, a power isolation feedback circuit. The whole feedback circuit is divided into 12 parts. The first part is a voltage sampling circuit, which consists of R1 and R2, and is used for completing the voltage sampling of the power supply module, wherein vin_H and vin_L are respectively high and low terminals output by the feedback power supply module; the second part is a first amplifier, and consists of resistors R3, R4, R5 and R6 and an operational amplifier LM358-1, and the circuit structure is an addition circuit; the third part is the first reference voltage, and consists of resistors R7, R8 and R9 and a reference voltage source TL 431-1. The fourth part is a 40KHz square wave generator circuit, which is realized by an active crystal oscillator Y1 and a capacitor C1. The fifth part is an amplitude modulation synthesis circuit, which is implemented by the multiplier AD734, the first path signal is input by the difference between X1 and X2, the output from the first amplifier, the second path signal is input by the difference between Y1 and Y2, and the output signal from the active crystal oscillator Y1. The sixth part of power amplifying circuit consists of an integrated power amplifying circuit LM386 and a capacitor C2, wherein a signal is from C1 and is input by a third pin of the LM 386; the seventh part is an ultrasonic transmitting and receiving circuit, which consists of a transmitting end P1, a receiving end P2 and isolating medium transformer oil. The eighth part is an impedance matching circuit and consists of an inductor L1 and a capacitor C3. The ninth part is a precision rectifying and filtering circuit, which is composed of resistors R10, R11, R12, R13, R14, R15 and R16, operational amplifiers LM358-2 and LM358-3 and diodes D1 and D2, and C4 completes the filtering function. The tenth part is a second amplifier, which consists of R17, R18, R19 and an operational amplifier LM358-4, and the circuit structure is a subtracting circuit. The eleventh part is the second reference voltage, and is composed of resistors R20, R21, R22 and a reference voltage source TL 431-2. The twelfth part is a control circuit and is realized by an 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 table, the optical coupling device feedback method has low isolation voltage level, small linear range and low cost, and can only feed back direct current voltage; the transformer has the advantages of large feedback volume, high weight, high isolation voltage level, high cost and small voltage linearity when small signals are generated, and can only feed back alternating voltage; the Hall voltage sensor has low feedback voltage level, high cost and small linearity range. The method used by the invention has the advantages of high isolation voltage level, small volume, good linearity in the whole range of small voltage and large voltage, low cost and suitability for feedback of alternating current and direct current voltage. Compared with the former three, the method can overcome the respective defects and has the respective advantages, and the comprehensive performance is very excellent.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart 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 comprising the steps of:
s1, performing partial pressure sampling on an input voltage signal to obtain a voltage sampling signal;
s2, applying a first reference voltage on the basis of the voltage sampling signal;
s3, synthesizing the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal, and performing power amplification processing on the first voltage signal to enable the first voltage signal to drive an ultrasonic transmission unit;
s4, 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;
s5, performing impedance matching, rectification and filtering on the second voltage signal to obtain a response voltage signal;
s6, applying a second reference voltage on the basis of the response voltage signal;
and S7, performing closed-loop control on the response voltage signal to obtain an output voltage signal.
2. A power isolation feedback circuit, comprising:
the voltage sampling unit comprises a first resistor and a second resistor and is used for performing partial pressure sampling on the output voltage of the power module which is fed back in an isolated manner to obtain a voltage sampling signal;
the constant amplitude carrier signal generator is used for generating constant amplitude carrier signals;
the amplitude modulation unit is used for synthesizing the voltage sampling signal and the constant-amplitude carrier signal to obtain a first voltage signal;
the ultrasonic transmission unit comprises an ultrasonic transmitting device, an ultrasonic receiving device and an insulating medium positioned between the ultrasonic transmitting device and the ultrasonic receiving device; the ultrasonic wave transmitting device is used for receiving the first voltage signal and converting the first voltage signal into an ultrasonic wave signal; the ultrasonic receiving device is used for receiving the ultrasonic signal and converting the ultrasonic signal into a second voltage signal;
the power amplification unit is arranged between the amplitude modulation unit and the ultrasonic wave transmitting device and is used for carrying out power amplification treatment on the first voltage signal so as to drive the ultrasonic wave transmitting device;
the signal recovery unit is used for rectifying and filtering the second voltage signal to obtain a response voltage signal;
the control unit is used for performing 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 arranged between the voltage sampling unit and the amplitude modulation unit, a first input end of the first amplifier is connected with an output end of the voltage sampling unit, a second input end of the first amplifier is connected with an output end of the first reference power supply, and an output end of the first amplifier is connected with a first input end of the amplitude modulation unit;
a second amplifier and a second reference power supply are further arranged between the signal reduction unit and the control unit, a first input end of the second amplifier is connected with an output end of the signal reduction unit, a second input end of the second amplifier is connected with an output end of the second reference power supply, and an output end of the second amplifier is connected with an input end of the control unit;
an impedance matching unit is further arranged between the ultrasonic receiving device and the reduction unit, and the impedance matching unit is used for performing impedance matching treatment on the ultrasonic receiving device;
the output end of the constant amplitude carrier signal generator is connected with the second input end of the amplitude modulation unit; the output end of the amplitude modulation unit is connected with the input end of the ultrasonic wave transmitting device, and the output end of the ultrasonic wave receiving device is connected with the input end of the signal restoring unit.
3. The power isolation feedback circuit of claim 2, wherein: the amplitude modulation unit is a multiplier.
4. A power isolation feedback circuit according to claim 2 or 3, wherein: the first amplifier and the second amplifier are both operational amplifiers.
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