Power converter, photovoltaic power generation system and uninterruptible power supply system

Abstract

The invention relates to the technical field of inversion, in particular to a power converter, a photovoltaic power generation system and an uninterruptible power supply system, and aims to solve the problems of large common-mode noise and poor signal quality of signals. The invention provides a power converter which comprises a common-mode attenuation circuit and an optical coupler isolation circuit, the common-mode attenuation circuit can obtain a direct-current component in output voltage, the optical coupler isolation circuit comprises a first comparator and an optical coupler device, and the first comparator can convert the direct-current component into a high-level signal or a low-level signal and transmit the high-level signal or the low-level signal to the optical coupler device. The optocoupler can convert a high-level signal or a low-level signal with direct-current component information into a first level signal or a zero-level signal and transmit the first level signal or the zero-level signal while ensuring that the input loop and the output loop are not electrically connected, that is, the optocoupler isolation circuit can convert the direct-current component into an isolated PWM (Pulse-Width Modulation) signal, and the PWM signal is transmitted to the output loop. Signal isolation is realized, so that the common-mode noise of the signal is reduced, and the quality of the signal is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of inverter technology, and particularly to a power converter, a photovoltaic power generation system, and an uninterruptible power supply system. Background Art

[0002] Inverters, uninterruptible power supplies and other power converters include an inverter circuit. The output voltage of the inverter circuit usually includes a DC component. If the DC component is too large, it will cause magnetic bias in the inductive load connected to the inverter, resulting in risks such as insulation damage. To monitor the DC component, it is usually necessary to sample the output voltage. However, the signal obtained by sampling, which contains DC component information, usually contains common-mode noise, resulting in poor signal quality. Summary of the Invention

[0003] The embodiments of the present application provide a power converter, a photovoltaic power generation system, and an uninterruptible power supply system, which can reduce the common-mode noise of the signal and improve the signal quality.

[0004] In a first aspect, the embodiments of the present application provide a power converter, including a common-mode attenuation circuit, a modulation wave generation circuit, and an opto-isolation circuit. The input end of the common-mode attenuation circuit is used to connect to the output end of the power converter. The common-mode attenuation circuit is used to extract the DC component in the output voltage of the power converter. The modulation wave generation circuit is used to generate a modulation wave signal.

[0005] The opto-isolation circuit includes a first comparator and an opto-coupler device. The first input end of the first comparator is connected to the output end of the common-mode attenuation circuit. The second input end of the first comparator is connected to the output end of the modulation wave generation circuit. The output end of the first comparator is connected to the input end of the opto-coupler device. The first output end of the opto-coupler device is respectively connected to the input end of the controller and a first reference power supply. The second output end of the opto-coupler device is grounded.

[0006] Wherein, the first comparator can compare the DC component and the modulation wave signal. When the voltage corresponding to the modulation wave signal is greater than the voltage corresponding to the DC component, the first comparator outputs a high-level signal, and the first output end of the opto-coupler device outputs a zero-level signal. When the voltage corresponding to the modulation wave signal is less than the voltage corresponding to the DC component, the first comparator outputs a low-level signal, and the first output end of the opto-coupler device outputs a first-level signal.

[0007] The power converter includes a common-mode attenuation circuit. Through the common-mode attenuation circuit, the DC component in the output voltage can be obtained. The opto-isolation circuit includes a first comparator and an opto-device. The first comparator can convert the DC component into a high-level signal or a low-level signal and transmit it to the opto-device. The opto-device can convert the high-level signal and the low-level signal with DC component information into a zero-level signal or a first-level signal and transmit them out while ensuring no electrical connection between the input loop and the output loop. That is to say, the opto-isolation circuit can convert the DC component into an isolated PWM signal, realizing signal isolation, reducing the common-mode noise of the signal of the input controller, and improving the signal quality.

[0008] In some embodiments that may include the above embodiments, the first comparator includes a first power supply terminal and a second power supply terminal. The first power supply terminal is used to connect to a second reference power supply, and the second power supply terminal is used to connect to a third reference power supply. The opto-device includes a light-emitting diode and a photosensitive device. The anode of the light-emitting diode is connected to the output terminal of the first comparator, and the cathode of the light-emitting diode is connected to the second power supply terminal.

[0009] When the voltage corresponding to the modulation wave signal is greater than the voltage corresponding to the DC component, the first power supply terminal of the first comparator is connected to the output terminal of the first comparator. The anode of the light-emitting diode is connected to the second reference power supply, and the cathode of the light-emitting diode is connected to the second power supply terminal and connected to the third reference power supply. At this time, the light-emitting diode is in the conducting state and will generate an optical signal. When the photosensitive device receives the optical signal, it can change the state of the photosensitive device, making the photosensitive device in the conducting state and outputting a zero-level signal.

[0010] In some embodiments that may include the above embodiments, the controller includes a capture port. The sampling circuit further includes a signal conditioning circuit. The signal conditioning circuit includes a fifth resistor. One end of the fifth resistor is connected to the first end of the photosensitive device, and the other end of the fifth resistor is connected to the input terminal of the capture port.

[0011] The fifth resistor can limit the magnitude of the first-level signal, avoid the magnitude of the first-level signal exceeding the voltage threshold of the capture port, and ensure the normal operation of the controller.

[0012] In some embodiments that may include the above embodiments, the signal conditioning circuit further includes a sixth resistor. One end of the sixth resistor is connected to the input terminal of the capture port, and the other end of the sixth resistor is connected to the ground terminal of the capture port.

[0013] The fifth resistor and the sixth resistor are in series. The voltage value of the first-level signal is equal to the voltage value of the first reference power supply. The voltage value of the first reference power supply may exceed the voltage threshold of the capture port. The sixth resistor can achieve voltage division, making the voltage value fed into the capture port further reduced.

[0014] In some embodiments that may include the above embodiments, the controller includes an ADC module, and the signal conditioning circuit further includes a filtering circuit. One end of the filtering circuit is connected to the input end of the ADC module, and the other end of the filtering circuit is connected to the ground end of the ADC module.

[0015] The input end of the ADC module receives an analog signal, while the signal output by the optocoupler device is a PWM signal. Therefore, it is necessary to set up a filtering circuit to convert the PWM signal into an analog signal.

[0016] In some embodiments that may include the above embodiments, the common-mode attenuation circuit includes a first capacitor and a first amplifier. One end of the first capacitor is connected to the live wire of the output end of the power converter, and the other end of the first capacitor is connected to the neutral wire of the output end of the power converter.

[0017] Since the direction of the AC component of the output voltage changes continuously, the first capacitor can continuously charge and discharge, so that the AC component can pass through the first capacitor. The voltage of the DC component is constant, and the voltage across the first capacitor is also constant. After the first capacitor is charged to the saturation state, no current will flow through, so the DC component cannot pass through the first capacitor. The first input end of the first amplifier is connected to the live wire, and the second input end of the first amplifier is connected to the neutral wire, so that the DC component can enter the first amplifier through the first input end to extract the DC component.

[0018] In some embodiments that may include the above embodiments, the common-mode attenuation circuit further includes a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor. One end of the seventh resistor is connected to the live wire, and the other end of the seventh resistor is connected to the first input end of the first amplifier. One end of the eighth resistor is connected to the neutral wire, and the other end of the eighth resistor is connected to the second input end of the first amplifier.

[0019] One end of the ninth resistor is connected to the first input end of the first amplifier, and the other end of the ninth resistor is grounded. One end of the tenth resistor is connected to the output end of the first amplifier, and the other end of the tenth resistor is connected to the second input end of the first amplifier.

[0020] The seventh resistor and the eighth resistor can limit the magnitude of the current input to the first amplifier to avoid damage to the first amplifier caused by excessive current. At the same time, by adjusting the resistance values of the seventh resistor and the eighth resistor, the signal strength of the DC component input to the first amplifier can be controlled, so as to achieve precise control of the amplification factor.

[0021] The ninth resistor divides the voltage with the first amplifier. The ninth resistor can adjust the value of the DC component entering the first amplifier, so that the DC component entering the first amplifier is within the voltage threshold of the first amplifier. The tenth resistor is connected to the output terminal and the second input terminal of the first amplifier respectively. That is to say, the tenth resistor is the negative feedback resistor of the first amplifier, and the current can return to the second input terminal of the first amplifier through the output terminal of the first amplifier. The tenth resistor can participate in determining the closed-loop gain of the first amplifier. By adjusting the resistance value of the tenth resistor, the gain of the first amplifier can be adjusted. At the same time, the negative feedback circuit can reduce the noise coefficient and distortion rate of the first amplifier circuit and improve the quality of the signal output by the first amplifier.

[0022] In some embodiments that may include the above embodiments, the common-mode attenuation circuit further includes a second capacitor and a third capacitor. One end of the second capacitor is connected to the first input terminal of the first amplifier, and the other end of the second capacitor is grounded. One end of the third capacitor is connected to the output terminal of the first amplifier, and the other end of the third capacitor is connected to the second input terminal of the first amplifier.

[0023] The second capacitor and the third capacitor can further filter the DC component, so that the remaining AC component in the DC component is eliminated.

[0024] In some embodiments that may include the above embodiments, the modulation wave generation circuit includes a second comparator and a second amplifier. The first input terminal of the second comparator is connected to the output terminal of the second comparator, the second input terminal of the second comparator is grounded, and the output terminal of the second comparator is connected to the output terminal of the second amplifier. The first input terminal of the second amplifier is grounded, the second input terminal of the second amplifier is connected to the output terminal of the second comparator, and the output terminal of the second amplifier is connected to the second input terminal of the second amplifier.

[0025] The modulation wave generation circuit further includes a fourth capacitor and an eleventh resistor. One end of the fourth capacitor is connected to the second input terminal of the second amplifier, the other end of the fourth capacitor is connected to the output terminal of the second amplifier, one end of the eleventh resistor is connected to the output terminal of the second comparator, and the other end of the eleventh resistor is connected to the second input terminal of the second amplifier.

[0026] When the output terminal of the second comparator is at a high voltage, the fourth capacitor is charged through the eleventh resistor, and the voltage at the output terminal of the second amplifier decreases linearly. Since the output terminal of the second amplifier is connected to the first input terminal of the second comparator, the voltage at the first input terminal of the second comparator also decreases linearly. When the voltage at the first input terminal of the second comparator drops below 0V, the output terminal of the second comparator jumps to a low voltage.

[0027] When the output of the second comparator is at a low voltage, the fourth capacitor discharges through the eleventh resistor, and the voltage at the output of the second amplifier rises linearly. Since the output of the second amplifier is connected to the first input of the second comparator, the voltage at the first input of the second comparator also rises linearly. When the voltage at the first input of the second comparator rises above 0V, the output of the second comparator jumps to a high voltage. In this cycle, the output of the second comparator outputs a square wave signal, and the output of the second amplifier outputs a triangular wave signal.

[0028] In some embodiments that may include the above embodiments, the modulation wave generation circuit further includes a twelfth resistor and a thirteenth resistor. One end of the twelfth resistor is connected to the output of the second comparator, and the other end of the twelfth resistor is connected to the first input of the second comparator. One end of the thirteenth resistor is connected to the first input of the second comparator, and the other end of the thirteenth resistor is connected to the output of the second amplifier.

[0029] The twelfth resistor and the thirteenth resistor can divide the voltage at the output of the second comparator to the first input of the second comparator and the output of the second amplifier, avoiding the voltage amplitude at the first input of the second comparator exceeding the voltage range that the second comparator can withstand.

[0030] The modulation wave generation circuit further includes a fourteenth resistor. One end of the fourteenth resistor is connected to the first input of the second amplifier, and the other end of the fourteenth resistor is grounded.

[0031] The fourteenth resistor can limit the magnitude of the input current, avoiding excessive current and causing damage to the second amplifier.

[0032] In a second aspect, an embodiment of the present application provides a photovoltaic power generation system, including the above-mentioned power converter. The power converter is used to connect to a photovoltaic module, and the power converter is also used to connect to a load.

[0033] The photovoltaic power generation system provided by the embodiment of the present application includes the power converter in any of the above embodiments, so the two can solve the same technical problems and achieve the same technical effects.

[0034] In a third aspect, an embodiment of the present application provides an uninterruptible power supply system, including the above-mentioned power converter. The power converter is used to connect to a power grid, and the power converter is also used to connect to a load.

[0035] The uninterruptible power supply system provided by the embodiment of the present application includes the power converter in any of the above embodiments, so the two can solve the same technical problems and achieve the same technical effects. Description of the Drawings

[0036] Figure 1Schematic diagram of the photovoltaic power generation system provided by the embodiment of the present application;

[0037] Figure 2 Schematic diagram of the uninterruptible power supply system provided by the embodiment of the present application;

[0038] Figure 3 Schematic diagram of the sampling circuit provided by the embodiment of the present application Figure 1 ;

[0039] Figure 4 Schematic diagram of the optocoupler isolation circuit provided by the embodiment of the present application;

[0040] Figure 5 Schematic diagram of the optocoupler isolation circuit and the signal conditioning circuit provided by the embodiment of the present application;

[0041] Figure 6 Schematic diagram of the signal conditioning circuit provided by the embodiment of the present application Figure 1 ;

[0042] Figure 7 Schematic diagram of the signal conditioning circuit provided by the embodiment of the present application Figure 2 ;

[0043] Figure 8 Schematic diagram of the common mode attenuation circuit provided by the embodiment of the present application;

[0044] Figure 9 Schematic diagram of the modulation wave generation circuit provided by the embodiment of the present application;

[0045] Figure 10 Schematic diagram of the sampling circuit provided by the embodiment of the present application Figure 2 ;

[0046] Figure 11 Waveform diagram of the comparison between the triangular wave and the DC component provided by the embodiment of the present application;

[0047] Figure 12 Waveform diagram of the comparison between the sine wave and the DC component provided by the embodiment of the present application;

[0048] Figure 13 Waveform diagram of the comparison between the trapezoidal wave and the DC component provided by the embodiment of the present application.

[0049] Description of the reference numerals:

[0050] 1: Photovoltaic power generation system; 2: Uninterruptible power supply system; 3: Load; 4: Sampling circuit; 5: Controller; 6: Power converter; 10: Inverter; 11: Rectifier; 20: Optocoupler isolation circuit; 21: First comparator; 211: First input terminal of the first comparator; 212: Second input terminal of the first comparator; 213: Output terminal of the first comparator; 214: First power supply terminal; 215: Second power supply terminal; 22: Optocoupler device; 221: Input terminal of the optocoupler device; 222: Output terminal of the optocoupler device; 23: Light-emitting diode; 24: Photosensitive device; 30: Capture port; 31: ADC module; 40: Common-mode attenuation circuit; 41: Input terminal of the common-mode attenuation circuit; 42: Output terminal of the common-mode attenuation circuit; 43: First amplifier; 431: First input terminal of the first amplifier; 432: Second input terminal of the first amplifier; 433: Output terminal of the first amplifier; 50: Modulation wave generation circuit; 501: Output terminal of the modulation wave generation circuit; 51: Second comparator; 511: First input terminal of the second comparator; 512: Second input terminal of the second comparator; 513: Output terminal of the second comparator; 514: First power supply terminal of the second comparator; 515: Second power supply terminal of the second comparator; 52: Second amplifier; 521: First input terminal of the second amplifier; 522: Second input terminal of the second amplifier; 523: Output terminal of the second amplifier; 524: First power supply terminal of the second amplifier; 525: Second power supply terminal of the second amplifier; 60: Signal conditioning circuit; 71: First resistor; 72: Second resistor; 73: Third resistor; 74: Fourth resistor; 75: Fifth resistor; 76: Sixth resistor; 77: Seventh resistor; 78: Eighth resistor; 79: Ninth resistor; 80: Tenth resistor; 81: Eleventh resistor; 82: Twelfth resistor; 83: Thirteenth resistor; 84: Fourteenth resistor; 91: First capacitor; 92: Second capacitor; 93: Third capacitor; 94: Fourth capacitor. Detailed implementation manners

[0051] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0052] Hereinafter, terms such as "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0053] In addition, in the embodiments of the present application, orientation terms such as "upper", "lower", "left", "right", "horizontal", and "vertical" are defined relative to the orientation in which the components in the drawings are schematically placed. It should be understood that these directional terms are relative concepts, which are used for relative description and clarification, and they can change accordingly with the change of the orientation in which the components in the drawings are placed.

[0054] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a direct connection, or an indirect connection through an intermediate medium. The connection can be the energy transmission and signal exchange between circuits.

[0055] It should be noted that in the description of the embodiments of the present application, unless otherwise clearly specified and limited, the terms "connected" and "connection" in the terms should be understood in a broad sense. For example, it can be a fixed connection, or an integral connection; it can also be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific situations.

[0056] Please refer to Figure 1 , the embodiments of the present application provide a photovoltaic power generation system 1. The photovoltaic power generation system 1 includes a photovoltaic module, a power converter 6, and a load 3. The power converter 6 can include an inverter (DC-AC) 10, which converts the direct current generated by the photovoltaic module into alternating current and transmits it to the load 3. One end of the inverter 10 can be connected to the photovoltaic module to receive direct current, and the other end of the inverter 10 can be connected to the load 3 to transmit alternating current to the load 3 and supply power to the load 3.

[0057] In the embodiment where the power converter 6 is the inverter 10, the power converter 6 further includes a sampling circuit 4 and a controller 5. The output end of the power converter 6 is connected to the input end of the sampling circuit 4, and the output end of the sampling circuit 4 is connected to the controller 5. The sampling circuit 4 can extract the DC component in the output voltage of the power converter 6 and transmit the DC component to the controller 5. The controller 5 can establish a closed-loop control circuit with the inverter 10 and continuously adjust the output voltage of the power converter 6 to reduce the DC component in the output voltage of the power converter 6.

[0058] Please refer to Figure 2 , the embodiments of the present application also provide an uninterruptible power supply system 2. The uninterruptible power supply system 2 includes a power grid, a power converter 6, and a load 3, and can convert the alternating current from the power grid into alternating current with other values and transmit it to the load 3.

[0059] The power converter 6 may include a rectifier (AC-DC) 11 and an inverter 10. The input terminal of the rectifier 11 is connected to the power grid for receiving alternating current and converting the alternating current into direct current. The output terminal of the rectifier 11 is connected to the input terminal of the inverter 10. The inverter 10 can convert the direct current from the rectifier 11 into alternating current. The output terminal of the inverter 10 is connected to the load 3 and can transmit the alternating current to the load 3 to supply power to the load 3.

[0060] Since the uninterruptible power supply system 2 includes an inverter 10, the finally output alternating current may contain a DC component. Therefore, the power converter 6 in the uninterruptible power supply system 2 also needs to extract the DC component in the output voltage through the sampling circuit 4 and transmit the DC component to the controller 5. The controller 5 can establish a closed-loop control circuit with the inverter 10 to continuously adjust the output voltage of the inverter 10 so that the DC component in the output voltage of the inverter 10 is reduced.

[0061] Please refer to Figure 3 , the sampling circuit 4 provided in the embodiment of the present application includes a common-mode attenuation circuit 40, a modulation wave generation circuit 50, and an opto-isolation circuit 20. The input terminal 41 of the common-mode attenuation circuit is used to connect to the output terminal of the power converter 6 ( Figure 2 as shown) so that the output voltage of the power converter 6 enters the sampling circuit 4. The common-mode attenuation circuit 40 is used to extract the DC component in the output voltage of the power converter 6, and the modulation wave generation circuit 50 is used to generate a modulation wave signal.

[0062] The opto-isolation circuit 20 includes a first comparator 21 and an opto-coupler device 22. The first input terminal 211 of the first comparator is connected to the output terminal 42 of the common-mode attenuation circuit, the second input terminal 212 of the first comparator is connected to the output terminal 501 of the modulation wave generation circuit, and the output terminal 213 of the first comparator is connected to the input terminal 221 of the opto-coupler device. The output terminal 222 of the opto-coupler device includes a first output terminal and a second output terminal. The first output terminal of the opto-coupler device 22 is respectively connected to the input terminal of the controller 5 ( Figure 2 as shown) and a first reference power supply, and the second output terminal of the opto-coupler device 22 is grounded.

[0063] The first comparator 21 can compare the DC component and the modulation wave signal. When the voltage corresponding to the modulation wave signal is greater than the voltage corresponding to the DC component, the first comparator 21 outputs a high-level signal, and the first output terminal of the opto-coupler device 22 outputs a zero-level signal; when the voltage corresponding to the modulation wave signal is less than the voltage corresponding to the DC component, the first comparator 21 outputs a low-level signal, and the first output terminal of the opto-coupler device 22 outputs a first-level signal. It can be understood that the voltage value of the first-level signal is equal to the value of the first reference power supply.

[0064] When the optocoupler device 22 receives a high-level signal, it can convert the high-level signal into an optical signal and transmit it to the output loop. After receiving the optical signal, the output loop can convert it into a zero-level signal, realizing the conversion between the optical signal and the electrical signal. There is no electrical connection between the input loop and the output loop of the optocoupler device 22, and the output signal has no influence on the input end, making the signal of the input controller 5 an isolated signal, reducing the common-mode noise of the signal of the input controller 5, and thus improving the signal quality.

[0065] It can be understood that when the voltage corresponding to the modulation wave signal is greater than the voltage corresponding to the DC component, the first comparator 21 outputs a high-level signal; when the voltage corresponding to the modulation wave signal is less than the voltage corresponding to the DC component, the first comparator 21 outputs a low-level signal. That is to say, within one cycle, the signal output by the first comparator 21 is a Pulse Width Modulation (PWM) signal.

[0066] At the same time, when the voltage corresponding to the modulation wave signal is greater than the voltage corresponding to the DC component, the optocoupler device 22 outputs a zero-level signal; when the voltage corresponding to the modulation wave signal is less than the voltage corresponding to the DC component, the optocoupler device 22 outputs a first-level signal. That is to say, within one cycle, the signal output by the optocoupler device 22 is also a PWM signal.

[0067] The sampling circuit 4 includes a common-mode attenuation circuit 40. Through the common-mode attenuation circuit 40, the DC component in the output voltage can be obtained. The optocoupler isolation circuit 20 includes a first comparator 21 and an optocoupler device 22. The first comparator 21 can convert the DC component into a high-level signal or a low-level signal and transmit it to the optocoupler device 22. The optocoupler device 22 can, while ensuring no electrical connection between the input loop and the output loop, convert the high-level signal and the low-level signal with DC component information into a zero-level signal or a first-level signal and transmit them out. That is to say, the optocoupler isolation circuit 20 can convert the DC component into an isolated PWM signal, realizing signal isolation, reducing the common-mode noise of the signal of the input controller, and improving the signal quality.

[0068] It can be understood that in addition to the optocoupler device 22 used in this application, the isolation circuit can also adopt capacitive isolation devices and magnetic isolation devices to achieve the isolation effect.

[0069] In an embodiment where the isolation circuit adopts a capacitive isolation device, the capacitive isolation device includes a capacitor. The capacitor includes a first charged plate and a second charged plate. The first charged plate is connected to a first signal, and the first signal will affect the potential change of the capacitor, causing the first charged plate to obtain charge. Since there is a dielectric layer between the two charged plates for isolation, current cannot pass through, and only the charge can be transmitted to the second charged plate, causing a corresponding potential change at the output end of the second charged plate and outputting a second signal.

[0070] In an embodiment where a magnetic isolation device is used in the isolation circuit, the magnetic isolation device includes a primary coil and a secondary coil. After the primary coil receives the first signal, a local magnetic field is formed, and an induced current is correspondingly generated in the secondary coil to output the second signal.

[0071] Please refer to Figure 4 , in the above embodiment, the first comparator 21 includes a first power supply terminal 214 and a second power supply terminal 215. The first power supply terminal 214 is used to connect to the second reference power supply, and the second power supply terminal 215 is used to connect to the third reference power supply. It can be understood that the second reference power supply and the third reference power supply are generally symmetric power supplies. When the second reference power supply is a positive power supply, the third reference power supply is a negative power supply, and the amplitudes of the second reference power supply and the third reference power supply are equal. Exemplarily, the second reference power supply can be +3V, +3.3V, +5V, +12V, +15V, etc., and the third reference power supply can be -3V, -3.3V, -5V, -12V, -15V, etc.

[0072] The optocoupler device 22 includes a light-emitting diode 23 and a photosensitive device 24. The anode of the light-emitting diode 23 is connected to the output terminal 213 of the first comparator, and the cathode of the light-emitting diode 23 is connected to the second power supply terminal 215.

[0073] It can be understood that when the voltage corresponding to the modulation wave signal is greater than the voltage corresponding to the DC component, the first power supply terminal 214 of the first comparator 21 is connected to the output terminal 213 of the first comparator. The anode of the light-emitting diode 23 is connected to the second reference power supply, and the cathode of the light-emitting diode 23 is connected to the second power supply terminal 215 to connect to the third reference power supply. At this time, the light-emitting diode 23 is in a conducting state and will generate an optical signal. When the photosensitive device 24 receives the optical signal, the state of the photosensitive device 24 can be changed, so that the photosensitive device 24 is in a conducting state and outputs a zero-level signal.

[0074] Continue to refer to Figure 4 , in the above embodiment, the first end of the photosensitive device 24 is connected to the first reference power supply, and the second end of the photosensitive device 24 is grounded. It can be understood that the first end of the photosensitive device 24 is the first output terminal of the optocoupler device 22, and the second end of the photosensitive device 24 is the second output terminal of the optocoupler device 22. When the photosensitive device 24 is conducting, the output terminal of the photosensitive device 24 is grounded and outputs a zero-level signal. When the photosensitive device 24 is in a non-conducting state, the first reference power supply is connected to the output terminal of the photosensitive device 24 to output a first-level signal. That is to say, the signal output by the photosensitive device 24 is a PWM signal.

[0075] The embodiment of the present application does not limit the magnitude of the first reference power supply. Exemplarily, the first reference power supply can be +3V, +3.3V, +5V, +12V, +15V, etc.

[0076] To further ensure the isolation at both ends of the optocoupler device 22, the first power supply ground of the second reference power supply and the third reference power supply connected to the input end 221 of the optocoupler device is different from the second power supply ground of the first reference power supply connected to the output end 222 ( Figure 3 as shown), so as to avoid signal interference with each other when transmitted to the power supply ground and affect the isolation effect.

[0077] Please refer to Figure 5 , in some embodiments, the photosensitive device 24 includes a photosensitive triode, the collector of the photosensitive triode is connected to the first reference power supply, and the emitter of the photosensitive triode is grounded.

[0078] Continue to refer to Figure 5 , in the above embodiment, the optocoupler isolation circuit 20 includes a first resistor 71 and a second resistor 72. One end of the first resistor 71 is connected to the first power supply terminal 214, and the other end of the first resistor 71 is connected to the output terminal 213 of the first comparator. One end of the second resistor 72 is connected to the first reference power supply, and the other end of the second resistor 72 is connected to the first end of the photosensitive device 24.

[0079] It can be understood that since the first end of the photosensitive device 24 is connected to the first reference power supply and the second end is grounded, in the embodiment without setting the second resistor 72, when the photosensitive device 24 is turned on, the first reference power supply and the ground are directly connected, which will cause the current passing through the photosensitive device 24 to be too large and easily damage the photosensitive device 24.

[0080] The second resistor 72 can reduce the magnitude of the current passing through the photosensitive device 24 and ensure the normal operation of the photosensitive device 24.

[0081] The optocoupler isolation circuit 20 further includes a third resistor 73 and a fourth resistor 74. One end of the third resistor 73 is connected to the output terminal 501 of the modulation wave generation circuit, the other end of the third resistor 73 is connected to the first input terminal 211 of the first comparator, one end of the fourth resistor 74 is connected to the output terminal 42 of the common-mode attenuation circuit, and the other end of the fourth resistor 74 is connected to the second input terminal 212 of the first comparator.

[0082] The third resistor 73 and the fourth resistor 74 can limit the magnitudes of the DC component and the modulation wave, avoid the magnitudes of the DC component and / or the modulation wave exceeding the voltage threshold that the first comparator 21 can withstand, and ensure the normal operation of the first comparator 21.

[0083] In the above embodiment, the controller 5 includes a Capture (CAP) port 30, a power converter 6 ( Figure 2As shown, it also includes a signal conditioning circuit 60. The signal conditioning circuit 60 includes a fifth resistor 75. One end of the fifth resistor 75 is connected to the first end of the photosensitive device 24, and the other end of the fifth resistor 75 is connected to the input end of the capture port 30. The CAP port can receive the signal from the photosensitive device 24 and transmit it to the closed-loop control circuit inside the controller 5.

[0084] The fifth resistor 75 can limit the magnitude of the first-level signal, avoid the magnitude of the first-level signal exceeding the voltage threshold that the capture port 30 can withstand, and ensure the normal operation of the controller 5.

[0085] Please refer to Figure 6 , in the above embodiment, the signal conditioning circuit 60 further includes a sixth resistor 76. One end of the sixth resistor 76 is connected to the input end of the CAP port 30, and the other end of the sixth resistor 76 is connected to the ground end of the CAP port 30. It can be understood that the fifth resistor 75 and the sixth resistor 76 are in series. The voltage value of the first-level signal is equal to the voltage value of the first reference power supply. The voltage of the first reference power supply may exceed the voltage threshold that the CAP port 30 can withstand. The sixth resistor 76 can achieve voltage division, so that the voltage amplitude corresponding to the first-level signal is within the voltage range that the CAP port can withstand.

[0086] Please refer to Figure 7 , in some embodiments, the controller 5 includes an analog-to-digital converter (ADC) module 31. The signal conditioning circuit 60 further includes a filtering circuit. One end of the filtering circuit is connected to the input end of the ADC module 31, and the other end of the filtering circuit is connected to the ground end of the ADC module 31. The input end of the ADC module 31 receives an analog signal, and the second signal output by the optocoupler device 22 is a PWM signal. Therefore, a filtering circuit needs to be set to convert the PWM signal into an analog signal.

[0087] The embodiments of the present application do not limit the filtering circuit. Exemplarily, the filtering circuit may include a capacitor.

[0088] Please refer to Figure 8 , in the above embodiment, the common-mode attenuation circuit 40 includes a first capacitor 91 and a first amplifier 43. One end of the first capacitor 91 is connected to the live wire of the power supply, and the other end of the first capacitor 91 is connected to the neutral wire of the power supply. Since the direction of the AC component of the output voltage changes continuously, the first capacitor 91 can continuously charge and discharge, so that the AC component can pass through the first capacitor 91. The voltage of the DC component is constant, and the voltage across the first capacitor 91 is also constant. After the first capacitor 91 is charged to the saturation state, no current will flow through, so the DC component cannot pass through the first capacitor 91.

[0089] The first input terminal 431 of the first amplifier is connected to the live wire of the output terminal of the power converter 6 ( Figure 2 as shown), the second input terminal 432 of the first amplifier is connected to the neutral wire of the output terminal of the power converter 6, so that the DC component can enter the first amplifier 43 through the first input terminal, and the extraction of the DC component is realized.

[0090] In the above embodiment, the common-mode attenuation circuit 40 further includes a seventh resistor 77, an eighth resistor 78, a ninth resistor 79 and a tenth resistor 80. One end of the seventh resistor 77 is connected to the live wire, and the other end of the seventh resistor 77 is connected to the first input terminal 431 of the first amplifier. One end of the eighth resistor 78 is connected to the neutral wire, and the other end of the eighth resistor 78 is connected to the second input terminal 432 of the first amplifier.

[0091] It can be understood that the seventh resistor 77 and the eighth resistor 78 can limit the magnitude of the current input to the first amplifier 43 and prevent damage to the first amplifier 43 caused by excessive current. At the same time, by adjusting the resistance values of the seventh resistor 77 and the eighth resistor 78, the signal strength of the DC component input to the first amplifier 43 can be controlled, so as to realize the precise control of the amplification factor.

[0092] One end of the ninth resistor 79 is connected to the first input terminal 431 of the first amplifier, and the other end of the ninth resistor 79 is grounded. One end of the tenth resistor 80 is connected to the output terminal 433 of the first amplifier, and the other end of the tenth resistor 80 is connected to the second input terminal 432 of the first amplifier.

[0093] It can be understood that the ninth resistor 79 divides the voltage with the first amplifier 43, and the ninth resistor 79 can adjust the value of the DC component entering the first amplifier 43, so that the DC component entering the first amplifier 43 is within the voltage threshold of the first amplifier 43.

[0094] The tenth resistor 80 is respectively connected to the output terminal 433 and the second input terminal of the first amplifier. That is to say, the tenth resistor 80 is the negative feedback resistor of the first amplifier 43, and the current can return to the second input terminal 432 of the first amplifier through the output terminal 433 of the first amplifier. The tenth resistor 80 can participate in determining the closed-loop gain of the first amplifier 43. By adjusting the resistance value of the tenth resistor 80, the gain of the first amplifier 43 can be adjusted. At the same time, the negative feedback circuit can reduce the noise coefficient and distortion rate of the first amplifier circuit and improve the quality of the signal output by the first amplifier 43.

[0095] It can be understood that the resistance value of the seventh resistor 77 is R 7 , the resistance value of the eighth resistor 78 is R 8 , the resistance value of the ninth resistor 79 is R 9 , and the resistance value of the tenth resistor 80 is R 10, at R 7 = R 8 , R 9 = R 10 In the embodiment where 9 9 / R 7 , the voltage at the output terminal 433 of the first amplifier is R of the DC component

[0096] Continuing to refer to Figure 8 , in the above embodiment, the common-mode attenuation circuit 40 further includes a second capacitor 92 and a third capacitor 93. One end of the second capacitor 92 is connected to the first input terminal 431 of the first amplifier, and the other end of the second capacitor 92 is grounded. One end of the third capacitor 93 is connected to the output terminal 433 of the first amplifier, and the other end of the third capacitor 93 is connected to the second input terminal 432 of the first amplifier.

[0097] It can be understood that the second capacitor 92 and the third capacitor 93 can further filter the DC component, so that the residual AC component in the DC component is eliminated.

[0098] Please refer to Figure 9 , in the above embodiment, the modulation wave generation circuit 50 includes a second comparator 51 and a second amplifier 52. The first input terminal 511 of the second comparator is connected to the output terminal 513 of the second comparator. The second input terminal 512 of the second comparator is grounded. The output terminal 513 of the second comparator is connected to the output terminal 523 of the second amplifier. The first input terminal 521 of the second amplifier is grounded. The second input terminal 522 of the second amplifier is connected to the output terminal 513 of the second comparator. The output terminal 523 of the second amplifier is connected to the second input terminal 522 of the second amplifier.

[0099] The modulation wave generation circuit 50 further includes a fourth capacitor 94 and an eleventh resistor 81. One end of the fourth capacitor 94 is connected to the second input terminal 522 of the second amplifier, and the other end of the fourth capacitor 94 is connected to the output terminal 523 of the second amplifier. One end of the eleventh resistor 81 is connected to the output terminal 513 of the second comparator, and the other end of the eleventh resistor 81 is connected to the second input terminal 522 of the second amplifier.

[0100] It can be understood that when the output terminal 513 of the second comparator is at a high voltage, the fourth capacitor 94 is charged through the eleventh resistor 81, and the voltage at the output terminal 523 of the second amplifier linearly decreases. Since the output terminal 523 of the second amplifier is connected to the first input terminal 511 of the second comparator, the voltage at the first input terminal 511 of the second comparator also linearly decreases. When the voltage at the first input terminal 511 of the second comparator drops below 0V, the output terminal 513 of the second comparator jumps to a low voltage.

[0101] When the output terminal 513 of the second comparator is at a low voltage, the fourth capacitor 94 discharges through the eleventh resistor 81, and the voltage at the output terminal 523 of the second amplifier rises linearly. Since the output terminal 523 of the second amplifier is connected to the first input terminal 511 of the second comparator, the voltage at the first input terminal 511 of the second comparator also rises linearly. When the voltage at the first input terminal 511 of the second comparator rises above 0V, the output terminal 513 of the second comparator jumps to a high voltage. In such a cycle, the output terminal 513 of the second comparator outputs a square wave signal, and the output terminal 523 of the second amplifier outputs a triangular wave signal.

[0102] In the above embodiment, the first power supply terminal 514 of the second comparator is connected to the second reference power supply, and the second power supply terminal 515 of the second comparator is connected to the third reference power supply.

[0103] It can be understood that when the voltage at the first input terminal 511 of the second comparator is greater than the voltage at the second input terminal 512 of the second comparator, the output terminal 513 of the second comparator is connected to the first power supply terminal 514 of the second comparator, and the output voltage of the second comparator 51 is the second reference power supply; when the voltage at the first input terminal 511 of the second comparator is less than the voltage at the second input terminal 512 of the second comparator, the output terminal 513 of the second comparator is connected to the second power supply terminal 515 of the second comparator, and the output voltage of the second comparator 51 is the third reference power supply.

[0104] In the above embodiment, the first power supply terminal 524 of the second amplifier is connected to the second reference power supply, and the second power supply terminal 525 of the second amplifier is connected to the third reference power supply.

[0105] Continue to refer to Figure 9 and Figure 10 In the above embodiment, the modulation wave generation circuit 50 further includes a twelfth resistor 82 and a thirteenth resistor 83. One end of the twelfth resistor 82 is connected to the output terminal 513 of the second comparator, and the other end of the twelfth resistor 82 is connected to the first input terminal 511 of the second comparator. One end of the thirteenth resistor 83 is connected to the first input terminal 511 of the second comparator, and the other end of the thirteenth resistor 83 is connected to the output terminal 523 of the second amplifier.

[0106] It can be understood that the twelfth resistor 82 and the thirteenth resistor 83 can divide the voltage at the output terminal 513 of the second comparator to the first input terminal 511 of the second comparator and the output terminal 523 of the second amplifier, avoiding the voltage amplitude input to the first input terminal 511 of the second comparator from exceeding the voltage range that the second comparator 51 can withstand.

[0107] The resistance value of the twelfth resistor 82 is R 12 and the resistance value of the thirteenth resistor 83 is R 13, since the second reference power supply and the third reference power supply are symmetric power supplies with equal amplitudes, the voltage amplitude at the output terminal 513 of the second comparator is VCC2 (VCC2 = VCC3). The voltage at the output terminal 523 of the second amplifier is VCC2(R 13 / R 12 ), that is to say, the amplitude of the triangular wave is VCC2(R 13 / R 12 ).

[0108] Since the fourth capacitor 94 and the eleventh resistor 81 are involved in the integration process, the capacitance of the fourth capacitor 94 is C 4 , the resistance of the eleventh resistor 81 is R 11 , and the frequency of the generated triangular wave is approximately R 12 / (4R 13 R 11 C 4 ).

[0109] The modulation wave generation circuit 50 further includes a fourteenth resistor 84. One end of the fourteenth resistor 84 is connected to the first input terminal 521 of the second amplifier, and the other end of the fourteenth resistor 84 is grounded. The fourteenth resistor 84 can limit the magnitude of the input current to avoid excessive current and damage to the second amplifier 52.

[0110] It can be understood that in addition to the above triangular wave, the modulation wave can also be a trapezoidal wave, a sine wave, etc. In addition to using the second comparator 51 and the second amplifier 52, the modulation wave generation circuit 50 can also use Complementary Metal-Oxide-Semiconductor (CMOS).

[0111] Please refer to Figure 11 , Figure 11 is the waveform diagram when the modulation wave is a triangular wave. The modulation wave is a triangular wave, the DC component is continuous and the amplitude is constant. By comparing the magnitudes of the triangular wave and the DC component within one period, it can be obtained that the signal output by the first comparator 21( Figure 10 shown) is a PWM signal. Figure 12 is the waveform diagram when the modulation wave is a sine wave,[[]] Figure 13 is the waveform diagram when the modulation wave is a trapezoidal wave. The situations of the sine wave and the trapezoidal wave are similar to those of the triangular wave and will not be elaborated here.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power converter, characterized in that: include: A common mode attenuation circuit, wherein the input end of the common mode attenuation circuit is used to connect to the output end of the power converter, and the common mode attenuation circuit is used to extract a DC component in the output voltage of the power converter; A modulation wave generating circuit, wherein the modulation wave generating circuit is used to generate a modulation wave signal; An optocoupler isolation circuit, the optocoupler isolation circuit comprising a first comparator and an optocoupler device, wherein a first input end of the first comparator is connected to an output end of the common-mode attenuation circuit, a second input end of the first comparator is connected to an output end of the modulation wave generating circuit, an output end of the first comparator is connected to an input end of the optocoupler device, a first output end of the optocoupler device is respectively connected to an input end of a controller and a first reference power supply, and a second output end of the optocoupler device is grounded; Wherein, the first comparator is used to compare the DC component and the modulated wave signal; When the voltage corresponding to the modulated wave signal is greater than the voltage corresponding to the DC component, the first comparator outputs a high-level signal, and the first output terminal of the optical coupler device outputs a zero-level signal; When the voltage corresponding to the modulated wave signal is less than the voltage corresponding to the DC component, the first comparator outputs a low level signal, and the first output terminal of the optocoupler device outputs a first level signal.

2. The power converter according to claim 1, characterized in that: The first comparator comprises a first power supply terminal and a second power supply terminal, the first power supply terminal is used to connect to a second reference power supply, and the second power supply terminal is used to connect to a third reference power supply; The optocoupler device includes a light emitting diode and a photosensitive device. The anode of the light emitting diode is connected to the output end of the first comparator, and the cathode of the light emitting diode is connected to the second power supply end.

3. The power converter according to claim 1 or 2, characterized in that: A first terminal of the photosensitive device is connected to the first reference power supply, and a second terminal of the photosensitive device is grounded.

4. The power converter according to claim 3, characterized in that: The optocoupler isolation circuit comprises a first resistor, a second resistor, a third resistor and a fourth resistor, one end of the first resistor is connected to the first power supply end, the other end of the first resistor is connected to the output end of the first comparator, one end of the second resistor is connected to the first reference power supply, and the other end of the second resistor is connected to the first end of the photosensitive device; One end of the third resistor is connected to the output end of the modulation wave generating circuit, the other end of the third resistor is connected to the first input end of the first comparator, one end of the fourth resistor is connected to the output end of the common mode attenuation circuit, and the other end of the fourth resistor is connected to the second input end of the first comparator.

5. The power converter according to claim 3 or 4, characterized in that: The power converter also includes a signal conditioning circuit, the controller includes a capture port, and the signal conditioning circuit includes a fifth resistor, one end of the fifth resistor is connected to the first end of the photosensitive device, and the other end of the fifth resistor is connected to the input end of the capture port.

6. The power converter according to claim 5, characterized in that: The signal conditioning circuit further includes a sixth resistor, one end of the sixth resistor is connected to the input end of the capture port, and the other end of the sixth resistor is connected to the ground end of the capture port.

7. The power converter according to claim 5, characterized in that: The controller includes an ADC module, and the signal conditioning circuit also includes a filter circuit, one end of the filter circuit is connected to the input end of the ADC module, and the other end of the filter circuit is connected to the ground end of the ADC module.

8. The power converter according to any one of claims 1 to 7, characterized in that: The modulation wave generating circuit includes a second comparator, a second amplifier, an eleventh resistor and a fourth capacitor, the first input terminal of the second comparator is connected to the output terminal of the second comparator, the second input terminal of the second comparator is grounded, and the output terminal of the second comparator is connected to the output terminal of the second amplifier; A first input terminal of the second amplifier is grounded, a second input terminal of the second amplifier is connected to an output terminal of the second comparator, and an output terminal of the second comparator is connected to a second input terminal of the second amplifier; One end of the fourth capacitor is connected to the second input end of the second amplifier, and the other end of the fourth capacitor is connected to the output end of the second amplifier. One end of the eleventh resistor is connected to the output end of the second comparator, and the other end of the eleventh resistor is connected to the second input end of the second amplifier.

9. The power converter according to claim 8, characterized in that: The modulation wave generating circuit further includes a twelfth resistor, a thirteenth resistor and a fourteenth resistor, one end of the twelfth resistor is connected to the output end of the second comparator, and the other end of the twelfth resistor is connected to the first input end of the second comparator; One end of the thirteenth resistor is connected to the first input end of the second comparator, and the other end of the thirteenth resistor is connected to the output end of the second amplifier; One end of the fourteenth resistor is connected to the first input end of the second amplifier, and the other end of the fourteenth resistor is grounded.

10. The power converter according to any one of claims 1 to 9, characterized in that: The common-mode attenuation circuit comprises a first capacitor and a first amplifier, one end of the first capacitor is connected to the live wire of the output end of the power converter, and the other end of the first capacitor is connected to the neutral wire of the output end of the power converter; The output end of the first amplifier is connected to the first input end of the comparator, the first input end of the first amplifier is connected to the live wire, and the second input end of the first amplifier is connected to the neutral wire.

11. The power converter according to claim 10, characterized in that: The common-mode attenuation circuit further includes a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor, one end of the seventh resistor is connected to the live wire, the other end of the seventh resistor is connected to the first input end of the first amplifier, one end of the eighth resistor is connected to the neutral wire, and the other end of the eighth resistor is connected to the second input end of the first amplifier; One end of the ninth resistor is connected to the first input end of the first amplifier, and the other end of the ninth resistor is grounded. One end of the tenth resistor is connected to the output end of the first amplifier, and the other end of the tenth resistor is connected to the second input end of the first amplifier.

12. The power converter according to claim 10 or 11, characterized in that: The common-mode attenuation circuit further includes a second capacitor and a third capacitor, one end of the second capacitor is connected to the first input end of the first amplifier, and the other end of the second capacitor is grounded; One end of the third capacitor is connected to the output end of the first amplifier, and the other end of the third capacitor is connected to the second input end of the first amplifier.

13. A photovoltaic power generation system, characterized in that: The power converter comprises the power converter according to any one of claims 1 to 12, wherein the power converter is used to be connected to a photovoltaic component, and the power converter is also used to be connected to a load.

14. An uninterruptible power supply system, characterized in that: The invention comprises a power converter as described in any one of claims 1 to 12, wherein the power converter is used to be connected to a power grid, and the power converter is also used to be connected to a load.

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