Detection circuit for direct current component of voltage of energy storage inverter

Abstract

The invention discloses a detection circuit for a voltage direct-current component of an energy storage inverter. The detection circuit comprises a first direct-current component detection unit, a second direct-current component detection unit, a voltage grade selection unit and a control unit, the first direct-current component detection unit is connected with the phase voltage output end and is used for generating first direct-current voltage according to an accessed phase voltage alternating-current signal; the second direct-current component detection unit is connected with the phase voltage output end and is used for generating a second direct-current voltage according to the accessed phase voltage alternating-current signal; the output end of the control unit is connected with the gating end of the voltage grade selection unit, and the control unit is used for outputting gating signals to the voltage grade selection unit; the voltage level selection unit is used for outputting one of the first direct-current voltage and the second direct-current voltage to the control unit according to the gating signal. And different direct current component detection units are arranged to meet the requirements on voltage direct current component detection precision in different occasions.

Description

Technical Field

[0001] The present invention relates to the technical field of inverters, and particularly to a detection circuit for the DC component of the voltage of a energy storage inverter. Background Art

[0002] With the development of photovoltaic energy storage technology and the change of market demand, more and more users begin to demand household energy storage inverters for power supply. The excess power generated during the day is stored in the battery for use at night or for emergency power supply, and the excess power is output to the grid side through the grid-connected mode. In the off-grid mode, the energy storage inverter needs to work off-grid with a load. When working off-grid, due to the sampling error of the current sensor, the time delay generated by the hardware circuit, and the type of load carried, such as half-wave load, etc., the zero point of the inverter AC output voltage will deviate, generating a DC component of the voltage. If the DC component is relatively large, it will lead to the risk of saturation of the magnetic core of the rear-end transformer and possible damage to the load due to voltage imbalance. Therefore, it is required that the household energy storage inverter must meet certain requirements for the DC component of the voltage when working off-grid. Different application scenarios have different requirements for the magnitude of the DC component. Some requirements are relatively broad, and some requirements are strict, reaching the mV level. Therefore, a relatively accurate DC component detection circuit is needed to meet the adjustment needs of the entire software control system and reach within the required voltage DC component range value. Summary of the Invention

[0003] The present invention provides a detection circuit for the DC component of the voltage of an energy storage inverter to meet the requirements for the detection accuracy of the DC component of the voltage in different scenarios.

[0004] According to one aspect of the present invention, there is provided a detection circuit for the DC component of the voltage of an energy storage inverter. The energy storage inverter includes at least one phase voltage output terminal. The detection circuit for the DC component of the voltage of the energy storage inverter includes a DC component detection module corresponding to the phase voltage output terminal of the energy storage inverter. The DC component detection module includes: a first DC component detection unit, a second DC component detection unit, a voltage level selection unit, and a control unit;

[0005] The first DC component detection unit is connected to the phase voltage output terminal and is used for generating a first DC voltage according to the accessed phase voltage AC signal;

[0006] The second DC component detection unit is connected to the phase voltage output terminal and is used for generating a second DC voltage according to the accessed phase voltage AC signal;

[0007] The output terminal of the control unit is connected to the gating terminal of the voltage level selection unit and is used for outputting a gating signal to the voltage level selection unit;

[0008] The first input terminal of the voltage level selection unit is connected to the first DC component detection unit, the second input terminal of the voltage level selection unit is connected to the second DC component detection unit, and the output terminal of the voltage level selection unit is connected to the input terminal of the control unit, and is used to output one of the first DC voltage or the second DC voltage to the control unit according to the gating signal;

[0009] Wherein, the voltage acceptable by the first DC component detection unit is greater than or equal to a first voltage threshold and less than or equal to a second voltage threshold, the voltage acceptable by the second DC component detection unit is greater than or equal to a third voltage threshold and less than or equal to a fourth voltage threshold, the fourth voltage threshold is less than the second voltage threshold, and the third voltage threshold is greater than the first voltage threshold.

[0010] Optionally, the first DC component detection unit includes: a high-resistance differential detection sub-unit, a first filtering sub-unit, an amplifying sub-unit, and a first biasing sub-unit;

[0011] The first input terminal of the high-resistance differential detection sub-unit is connected to the phase voltage output terminal, the second input terminal of the high-resistance differential detection sub-unit is connected to the neutral line, and the high-resistance differential detection sub-unit is used to generate a first detection signal according to the phase voltage AC signal;

[0012] The first end of the first filtering sub-unit is connected to the output terminal of the high-resistance differential detection sub-unit, and is used to filter the AC signal in the first detection signal to generate a first filtered signal;

[0013] The input terminal of the amplifying sub-unit is connected to the second end of the first filtering sub-unit, and is used to amplify the first filtered signal to generate a first amplified signal;

[0014] The input terminal of the first biasing sub-unit is connected to the output terminal of the amplifying sub-unit, and is used to raise the zero voltage of the DC signal in the first amplified signal to generate the first DC voltage.

[0015] Optionally, the high-resistance differential detection sub-unit includes: a first resistor string, a second resistor string, a first clamping device, a first resistor, a second resistor, a third resistor, a first capacitor, a first operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, and a second capacitor;

[0016] The first resistor string includes at least two resistors connected in series. The first end of the first resistor string is connected to the phase voltage output terminal, the second end of the first resistor string is connected to the first end of the first resistor, the second end of the first resistor is connected to the first input terminal of the first operational amplifier, and the second resistor, the third resistor, and the first capacitor are connected in parallel between the first input terminal of the first operational amplifier and the ground terminal;

[0017] The second resistor string includes at least two resistors connected in series. The first end of the second resistor string is connected to the neutral line. The second end of the second resistor string is connected to the first end of the fourth resistor. The second end of the fourth resistor is connected to the second input terminal of the first operational amplifier;

[0018] The first end of the fifth resistor is connected to the second input terminal of the first operational amplifier. The second end of the fifth resistor is connected to the ground terminal. The sixth resistor and the second capacitor are connected in parallel between the second input terminal of the first operational amplifier and the output terminal of the first operational amplifier;

[0019] The first clamping device is connected between the second end of the first resistor string and the second end of the second resistor string. The first clamping device is used to limit the voltage between the second end of the first resistor string and the second end of the second resistor string within a first regulated voltage range;

[0020] The first filtering sub-unit includes: a seventh resistor, a third capacitor, an eighth resistor, and a fourth capacitor;

[0021] The first end of the seventh resistor is connected to the output terminal of the high-impedance differential detection sub-unit. The second end of the seventh resistor is connected to the first end of the third capacitor. The second end of the third capacitor is connected to the ground terminal;

[0022] The first end of the eighth resistor is connected to the second end of the seventh resistor. The second end of the eighth resistor is connected to the first end of the fourth capacitor. The second end of the fourth capacitor is connected to the ground terminal. The second end of the eighth resistor is also connected to the input terminal of the amplification sub-unit;

[0023] The amplification sub-unit includes: a second operational amplifier, a ninth resistor, and a tenth resistor;

[0024] The first input terminal of the second operational amplifier is connected to the second end of the first filtering sub-unit. The first end of the ninth resistor is connected to the second input terminal of the second operational amplifier. The second end of the ninth resistor is connected to the ground terminal. The first end of the tenth resistor is connected to the second input terminal of the second operational amplifier. The second end of the tenth resistor is connected to the output terminal of the second operational amplifier. The output terminal of the second operational amplifier is connected to the input terminal of the first biasing sub-unit;

[0025] The first biasing sub-unit includes: a third operational amplifier, an eleventh resistor, a twelfth resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, a thirteenth resistor, and a fourteenth resistor;

[0026] The first end of the eleventh resistor is connected to the output end of the amplification sub-unit, the second end of the eleventh resistor is connected to the second input end of the third operational amplifier, and the twelfth resistor and the fifth capacitor are connected in parallel between the second input end and the output end of the third operational amplifier;

[0027] The first end of the sixth capacitor is connected to the first power supply, the second end of the sixth capacitor is connected to the ground terminal, the first end of the thirteenth resistor is connected to the first power supply, the second end of the thirteenth resistor is connected to the first input end of the third operational amplifier, and the fourteenth resistor and the seventh capacitor are connected in parallel between the first input end of the third operational amplifier and the ground terminal.

[0028] Optionally, the first DC component detection unit further includes: a first voltage follower sub-unit and a second filtering sub-unit;

[0029] The input end of the first voltage follower sub-unit is connected to the second end of the first filtering sub-unit, and is used for isolating the signal output from the output end of the voltage follower sub-unit from the first filtered signal;

[0030] The first end of the second filtering sub-unit is connected to the output end of the first voltage follower sub-unit, and the second end of the second filtering sub-unit is connected to the input end of the amplification sub-unit, and is used for filtering the AC signal in the signal output from the first voltage follower sub-unit.

[0031] Optionally, the first voltage follower sub-unit includes a fourth operational amplifier, the first input end of the fourth operational amplifier is connected to the second end of the first filtering sub-unit, and the second input end of the fourth operational amplifier is connected to the output end of the fourth operational amplifier;

[0032] The second filtering sub-unit includes a fifteenth resistor, an eighth capacitor, a sixteenth resistor and a ninth capacitor. The first end of the fifteenth resistor is connected to the output end of the fourth operational amplifier, the second end of the fifteenth resistor is connected to the first end of the eighth capacitor, the second end of the eighth capacitor is connected to the ground terminal, the first end of the sixteenth resistor is connected to the second end of the fifteenth resistor, the second end of the sixteenth resistor is connected to the input end of the amplification sub-unit, the first end of the ninth capacitor is connected to the second end of the sixteenth resistor, and the second end of the ninth capacitor is connected to the ground terminal.

[0033] Optionally, the first DC component detection unit further includes a first filtering and clamping sub-unit, which is connected between the output end of the first biasing sub-unit and the first input end of the voltage level selection unit, and is used for filtering the AC signal in the first DC voltage and limiting the first DC voltage within a first voltage.

[0034] Optionally, the first filtering embedding sub-unit includes a seventeenth resistor, a tenth capacitor, a first diode, and a second diode;

[0035] The first end of the seventeenth resistor is connected to the output end of the first biasing sub-unit, the second end of the seventeenth resistor is connected to the first input end of the voltage level selection unit, the first end of the tenth capacitor is connected to the second end of the seventeenth resistor, and the second end of the tenth capacitor is connected to the ground terminal;

[0036] The first end of the first diode is connected to the second end of the seventeenth resistor, the second end of the first diode is connected to a first voltage, the first end of the second diode is connected to the ground terminal, and the second end of the second diode is connected to the second end of the seventeenth resistor.

[0037] Optionally, the second DC component detection unit includes: a first-stage high-impedance detection sub-unit, a second-stage high-impedance detection sub-unit, a common-mode suppression sub-unit, a differential amplification sub-unit, and a second biasing sub-unit;

[0038] The first input end of the first-stage high-impedance detection sub-unit is connected to the phase voltage output end, the second input end of the first-stage high-impedance detection sub-unit is connected to the neutral line. The first-stage high-impedance detection sub-unit is used to filter out the AC signal in the phase voltage AC signal, generate a first DC extraction signal, and limit the voltage of the first DC extraction signal within a second voltage;

[0039] The first input end of the second-stage high-impedance detection sub-unit is connected to the first output end of the first-stage high-impedance detection sub-unit, the second input end of the second-stage high-impedance detection sub-unit is connected to the second output end of the first-stage high-impedance detection sub-unit. The second-stage high-impedance detection sub-unit is used to filter out the AC signal in the first DC extraction signal, generate a second DC extraction signal, and limit the voltage of the second DC extraction signal within a third voltage;

[0040] The first end of the common-mode suppression sub-unit is connected to the first output end of the second-stage high-impedance detection sub-unit, the second end of the common-mode suppression sub-unit is connected to the second output end of the second-stage high-impedance detection sub-unit. The common-mode suppression sub-unit is used to filter out the common-mode signal in the second DC extraction signal;

[0041] The first input end of the differential amplification sub-unit is connected to the first output end of the second-stage high-impedance detection sub-unit, the second input end of the differential amplification sub-unit is connected to the second output end of the second-stage high-impedance detection sub-unit. The differential amplification sub-unit is used to generate a second amplified signal according to the second DC extraction signal;

[0042] The input end of the second bias sub-unit is connected to the output end of the differential amplification sub-unit, and is used to raise the zero voltage of the DC signal in the second amplified signal to generate a second DC voltage.

[0043] Optionally, the first-stage high-impedance detection sub-unit includes: a third resistor string, a fourth resistor string, an eleventh capacitor, and a second clamping device. The third resistor string includes at least two resistors connected in series. The fourth resistor string includes at least two resistors connected in series. The first end of the third resistor string is connected to the phase voltage output end. The second end of the third resistor string is connected to the first input end of the second-stage high-impedance detection sub-unit. The first end of the fourth resistor string is connected to the neutral line. The second end of the fourth resistor string is connected to the second input end of the second-stage high-impedance detection sub-unit. The eleventh capacitor and the second clamping device are connected in parallel between the second end of the third resistor string and the second end of the fourth resistor string;

[0044] The second-stage high-impedance detection sub-unit includes: a fifth resistor string, a sixth resistor string, a twelfth capacitor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a thirteenth capacitor, a fourteenth capacitor, a fifteenth capacitor, and a third clamping device. The fifth resistor string includes at least two resistors connected in series. The sixth resistor string includes at least two resistors connected in series. The first end of the fifth resistor string is connected to the first output end of the first-stage high-impedance detection sub-unit. The second end of the fifth resistor string is connected to the first end of the eighteenth resistor. The nineteenth resistor and the twelfth capacitor are connected in parallel between the second end of the eighteenth resistor and the ground end. The second end of the eighteenth resistor is also connected to the first input end of the differential amplification sub-unit. The first end of the sixth resistor string is connected to the second output end of the first-stage high-impedance detection sub-unit. The second end of the sixth resistor string is connected to the first end of the twentieth resistor. The twenty-first resistor and the thirteenth capacitor are connected in parallel between the second end of the twentieth resistor and the ground end. The second end of the twentieth resistor is also connected to the second input end of the differential amplification sub-unit. The fourteenth capacitor is connected in parallel between the second end of the fifth resistor string and the second end of the sixth resistor string. The fifteenth capacitor and the third clamping device are connected in parallel between the second end of the eighteenth resistor and the second end of the twentieth resistor;

[0045] The common-mode suppression subunit includes: a third diode, a fourth diode, a fifth diode, and a sixth diode. The first end of the third diode is connected to the first output end of the second-stage high-impedance detection subunit, the second end of the third diode is connected to a fourth voltage, the first end of the fourth diode is connected to a fifth voltage, the second end of the fourth diode is connected to the first output end of the second-stage high-impedance detection subunit, the first end of the fifth diode is connected to the second output end of the second-stage high-impedance detection subunit, the second end of the fifth diode is connected to the fourth voltage, the first end of the sixth diode is connected to the fifth voltage, the second end of the sixth diode is connected to the second output end of the second-stage high-impedance detection subunit, and the fourth voltage and the fifth voltage are inverse-phase voltages;

[0046] The differential amplification subunit includes a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a sixteenth capacitor, a fifth operational amplifier, a twenty-fifth resistor, a twenty-sixth resistor, a twenty-seventh resistor, and a seventeenth capacitor;

[0047] The first end of the twenty-second resistor is connected to the first output end of the second-stage high-impedance detection subunit, the second end of the twenty-second resistor is connected to the first input end of the fifth operational amplifier, the twenty-third resistor, the twenty-fourth resistor, and the sixteenth capacitor are connected in parallel between the first input end of the fifth operational amplifier and the ground terminal, the first end of the twenty-fifth resistor is connected to the second output end of the second-stage high-impedance detection subunit, the second end of the twenty-fifth resistor is connected to the second input end of the fifth operational amplifier, the twenty-sixth resistor is connected between the second input end of the fifth operational amplifier and the ground terminal, and the twenty-seventh resistor and the seventeenth capacitor are connected in parallel between the second input end of the fifth operational amplifier and the output end of the fifth operational amplifier;

[0048] The second bias subunit includes: a sixth operational amplifier, a twenty-eighth resistor, and an eighteenth capacitor;

[0049] The first input end of the sixth operational amplifier is connected to the output end of the differential amplification subunit, the second input end of the sixth operational amplifier is connected to the output end of the sixth operational amplifier, the first end of the twenty-eighth resistor is connected to a first power supply, the second end of the twenty-eighth resistor is connected to the first input end of the sixth operational amplifier, the first end of the eighteenth capacitor is connected to the first end of the twenty-eighth resistor, and the second end of the eighteenth capacitor is connected to the ground terminal.

[0050] Optionally, the second DC component detection unit further includes: a second voltage follower subunit;

[0051] The first input terminal of the second voltage follower subunit is connected to the first output terminal of the second-stage high-impedance detection subunit, the first output terminal of the second voltage follower subunit is connected to the first input terminal of the differential amplification subunit, the second input terminal of the second voltage follower subunit is connected to the second output terminal of the second-stage high-impedance detection subunit, the second output terminal of the second voltage follower subunit is connected to the second input terminal of the differential amplification subunit. The second voltage follower subunit is used to isolate the signal between the signal input to the first input terminal of the differential amplification subunit and the signal output from the first output terminal of the second-stage high-impedance detection subunit, and isolate the signal between the signal input to the second input terminal of the differential amplification subunit and the signal output from the second output terminal of the second-stage high-impedance detection subunit.

[0052] Optionally, the second voltage follower subunit includes: a seventh operational amplifier and an eighth operational amplifier;

[0053] The first input terminal of the seventh operational amplifier is connected to the first output terminal of the second-stage high-impedance detection subunit, the second input terminal of the seventh operational amplifier is connected to the output terminal of the seventh operational amplifier, and the output terminal of the seventh operational amplifier is connected to the first input terminal of the differential amplification subunit;

[0054] The first input terminal of the eighth operational amplifier is connected to the second output terminal of the second-stage high-impedance detection subunit, the second input terminal of the eighth operational amplifier is connected to the output terminal of the eighth operational amplifier, and the output terminal of the eighth operational amplifier is connected to the second input terminal of the differential amplification subunit.

[0055] Optionally, the second DC component detection unit further includes: a twenty-ninth resistor and a nineteenth capacitor. The first end of the twenty-ninth resistor is connected to the output terminal of the differential amplification subunit, the second end of the twenty-ninth resistor is connected to the input terminal of the second biasing subunit, the first end of the nineteenth capacitor is connected to the second end of the twenty-ninth resistor, and the second end of the nineteenth capacitor is connected to the ground terminal.

[0056] Optionally, the second DC component detection unit further includes: a second filter clamping subunit, which is connected between the output terminal of the second biasing subunit and the second input terminal of the voltage level selection unit, and is used to filter out the AC signal in the second DC voltage and limit the second DC voltage within the first voltage.

[0057] Optionally, the second filter clamping subunit includes: a thirtieth resistor, a twentieth capacitor, a seventh diode and an eighth diode;

[0058] The first end of the thirtieth resistor is connected to the output end of the second bias sub-unit, the second end of the thirtieth resistor is connected to the first end of the twentieth capacitor, the second end of the twentieth capacitor is connected to the ground end, and the second end of the thirtieth resistor is connected to the second input end of the voltage level selection unit;

[0059] The first end of the seventh diode is connected to the second input end of the voltage level selection unit, the second end of the seventh diode is connected to a first voltage, the first end of the eighth diode is connected to the ground end, and the second end of the eighth diode is connected to the second input end of the voltage level selection unit.

[0060] Optionally, it further includes a third filtering and clamping unit, which is connected between the output end of the voltage level selection unit and the input end of the control unit, and is used to filter the voltage output by the voltage level selection unit and limit the voltage input to the input end of the control unit within the first voltage.

[0061] Optionally, the third filtering and clamping unit includes: a thirty-first resistor, a twenty-first capacitor, a ninth diode, and a twelfth diode;

[0062] The first end of the thirty-first resistor is connected to the output end of the voltage level selection unit, the second end of the thirty-first resistor is connected to the input end of the control unit, the first end of the twenty-first capacitor is connected to the second end of the thirty-first resistor, and the second end of the twenty-first capacitor is connected to the ground end;

[0063] The first end of the ninth diode is connected to the input end of the control unit, the second end of the ninth diode is connected to the first voltage, the first end of the twelfth diode is connected to the ground end, and the second end of the twelfth diode is connected to the input end of the control unit.

[0064] In the technical solution of the embodiment of the present invention, the first DC component detection unit and the second DC component detection unit simultaneously extract the DC component of the voltage output by the energy storage inverter from the AC voltage, and the ranges of the input voltages that the two DC component detection units can accept are different. The control unit controls the voltage level selection circuit to output the voltage generated by the DC component detection unit that meets the requirements according to the detection accuracy and control requirements. When the detection accuracy of the voltage DC component is relatively high, the control unit controls the voltage level selection unit to output the second DC voltage generated by the second DC component detection unit. When the detection accuracy of the voltage DC component is relatively low, the control unit controls the voltage level selection unit to output the first DC voltage generated by the first DC component detection unit. According to the different accuracy requirements for the detection of the voltage DC component, the voltage generated by different DC component detection units is selected for output to facilitate subsequent related control, meeting the accuracy requirements for the detection of the voltage DC component in various scenarios, and improving the applicability of the circuit and the accuracy of the detection of the voltage DC component.

[0065] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0067] Figure 1 It is a schematic structural diagram of a detection circuit for the DC component of the voltage of an energy storage inverter provided by an embodiment of the present invention;

[0068] Figure 2 It is a schematic structural diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided by an embodiment of the present invention;

[0069] Figure 3 It is a schematic structural diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided by an embodiment of the present invention;

[0070] Figure 4 It is a schematic structural diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided by an embodiment of the present invention;

[0071] Figure 5 It is a schematic structural diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided by an embodiment of the present invention;

[0072] Figure 6 A schematic structural diagram of another detection circuit for the DC component of the voltage of the energy storage inverter provided by an embodiment of the present invention;

[0073] Figure 7 A schematic structural diagram of another detection circuit for the DC component of the voltage of the energy storage inverter provided by an embodiment of the present invention. Specific embodiments

[0074] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0075] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0076] Figure 1 A schematic structural diagram of a detection circuit for the DC component of the voltage of the energy storage inverter provided by an embodiment of the present invention. Refer to Figure 1 , the energy storage inverter includes at least one phase voltage output terminal, and the detection circuit for the DC component of the voltage of the energy storage inverter includes a DC component detection module corresponding to the phase voltage output terminal of the energy storage inverter. The DC component detection module includes: a first DC component detection unit 10, a second DC component detection unit 11, a voltage level selection unit 12, and a control unit 13;

[0077] The first DC component detection unit 10 is connected to the phase voltage output terminal and is used to generate a first DC voltage according to the accessed phase voltage AC signal;

[0078] The second DC component detection unit 11 is connected to the phase voltage output terminal and is used to generate a second DC voltage according to the accessed phase voltage AC signal;

[0079] The output terminal of the control unit 13 is connected to the gating terminal of the voltage level selection unit 12, and is used to output a gating signal to the voltage level selection unit 12;

[0080] The first input terminal Y1 of the voltage level selection unit 12 is connected to the first DC component detection unit 10, the second input terminal Y2 of the voltage level selection unit 12 is connected to the second DC component detection unit 11, and the output terminal OUT of the voltage level selection unit 12 is connected to the input terminal of the control unit 13, and is used to output one of the first DC voltage or the second DC voltage to the control unit 13 according to the gating signal;

[0081] Wherein, the voltage acceptable by the first DC component detection unit 10 is greater than or equal to the first voltage threshold and less than or equal to the second voltage threshold, the voltage acceptable by the second DC component detection unit 11 is greater than or equal to the third voltage threshold and less than or equal to the fourth voltage threshold, the fourth voltage threshold is less than the second voltage threshold, and the third voltage threshold is greater than the first voltage threshold. Wherein, the voltage range acceptable by the first DC component detection unit 10 is the range of the voltage allowed to be input by the first DC component detection unit 10, and the voltage acceptable by the second DC component detection unit 11 is the range of the voltage allowed to be input by the second DC component detection unit 11.

[0082] The energy storage inverter can be a single-phase inverter, and the corresponding energy storage inverter only outputs one-phase voltage. The energy storage inverter can also be a multi-phase inverter. Taking a three-phase inverter as an example, the corresponding energy storage inverter includes three phase voltage output terminals and a neutral line. The three phase voltage output terminals are the A-phase output terminal, the B-phase output terminal, and the C-phase output terminal respectively. Among them, the voltage between the A-phase output terminal and the neutral line is the A-phase voltage, the voltage between the B-phase output terminal and the neutral line is the B-phase voltage, and the voltage between the C-phase output terminal and the neutral line is the C-phase voltage. The phase voltage output terminals correspond one-to-one with the DC component detection modules.

[0083] The phase voltage output terminal is used to output a phase voltage AC signal. The first DC component detection unit 10 is used to extract the DC component from the phase voltage AC signal output by the corresponding phase of the energy storage inverter, and generate a first DC voltage recognizable by the control unit 13 after a series of operations. The second DC component detection unit 11 is used to extract the DC component from the phase voltage AC signal output by the corresponding phase of the energy storage inverter, and generate a second DC voltage recognizable by the control unit 13 after a series of operations. The control unit 13 can be a microprocessor, such as DSP (Digital Signal Processing), or a single-chip microcomputer or ARM, etc., or other processing chips or circuits with the same or similar functions. The voltage level selection unit 12 can use a dual 4-channel analog multiplexing chip, or a multiplexing chip with fewer channels, or a selection switch, and devices or circuits with similar functions.

[0084] The voltage range that the first DC component detection unit 10 can detect is greater than the voltage range that the second DC component detection unit 11 can detect. Exemplarily, the first DC component detection unit 10 can detect a DC voltage component from -80V to 80V, and the second DC component detection unit 11 can detect a DC voltage component from -1V to 1V. The voltage range that the control unit 13 can identify is 0 - 3V. When the voltage level selection unit 12 controls the voltage at the first input terminal to be output to the control unit 13, if the voltage received at the input terminal of the control unit 13 is 3V, then the DC voltage component in the signal output by the energy storage inverter is 80V; if the voltage received at the input terminal of the control unit 13 is 0V, then the DC voltage component in the signal output by the energy storage inverter is -80V. When the voltage level selection unit 12 controls the voltage at the second input terminal to be output to the control unit 13, if the voltage received at the input terminal of the control unit 13 is 3V, then the DC voltage component in the signal output by the energy storage inverter is 1V; if the voltage received at the input terminal of the control unit 13 is 0V, then the DC voltage component in the signal output by the energy storage inverter is -1V. Thus, it can be seen that the detection of the second DC component detection unit 11 is more precise and the control accuracy is higher.

[0085] The control unit 13 is configured to control the voltage level selection unit 12 to output the first DC voltage or the second DC voltage to the control unit 13 according to the magnitude of the DC voltage component of the voltage output by the energy storage inverter and the control accuracy requirement. The control unit 13 is configured to receive, according to the default setting, the voltage output from the output terminal OUT of the voltage level selection unit 12, and then control the voltage level selection unit 12 to output the first DC voltage or the second DC voltage according to the magnitude of the voltage output from the output terminal OUT of the voltage level selection unit 12 and the control accuracy requirement. The default setting may be that the default voltage level selection unit 12 outputs the first DC voltage. Exemplarily, after the control unit 13 receives the voltage output from the output terminal OUT of the voltage level selection unit 12 according to the default setting, if it is determined that the DC voltage component of the voltage output by the energy storage inverter is less than the fourth voltage threshold and the user requires a higher control accuracy, then the control unit 13 controls the voltage level selection unit 12 to output the second DC voltage to the control unit 13, and the control unit 13 performs subsequent closed-loop control according to the second DC voltage. If after the control unit 13 receives the voltage output from the output terminal OUT of the voltage level selection unit 12 according to the default setting, it is determined that the DC voltage component of the voltage output by the energy storage inverter is greater than the fourth voltage threshold and less than the second voltage threshold, then the control unit 13 controls the voltage level selection unit 12 to output the first DC voltage to the control unit 13, and the control unit 13 performs subsequent closed-loop control according to the first DC voltage.

[0086] The control unit 13 performs calculation processing on the received first DC voltage or second DC voltage, and issues a PWM wave to perform closed-loop control on the DC component in the phase voltage AC signal output by the energy storage inverter. Among them, if the voltage received by the control unit 13 is different, the pulse width and phase of the generated PWM wave are also different. Exemplarily, when the DC component of the voltage is greater than 1V, the control unit 13 performs closed-loop control according to the first DC voltage generated by the first DC component detection unit 10, and the effect is better. When the DC voltage component is less than or equal to 1V, the first DC component detection unit 10 cannot well meet the accuracy and control requirements of the DC component. Therefore, the second DC component detection unit 11 is used to process the relatively small DC component signal to meet the control requirements of the very small DC component. When high accuracy requirements appear, the entire voltage detection range can be calibrated in segments for accuracy to meet special requirements.

[0087] In the technical solution of the embodiment of the present invention, the DC component of the voltage output by the energy storage inverter is extracted from the AC voltage by the first DC component detection unit and the second DC component detection unit at the same time, and the ranges of the input voltages that the two DC component detection units can accept are different. The control unit controls the voltage level selection circuit to output the voltage generated by the DC component detection unit that meets the requirements according to the detection accuracy and control requirements. When the detection accuracy of the DC component of the voltage is relatively high, the control unit controls the voltage level selection unit to output the second DC voltage generated by the second DC component detection unit. When the detection accuracy of the DC component of the voltage is relatively low, the control unit controls the voltage level selection unit to output the first DC voltage generated by the first DC component detection unit. According to the different accuracy requirements for detecting the DC component of the voltage, the voltage generated by different DC component detection units is selected for output to facilitate subsequent related control, meet the accuracy requirements for detecting the DC component of the voltage in various scenarios, and improve the applicability of the circuit and the accuracy of detecting the DC component of the voltage.

[0088] Figure 2 FIG. is a schematic structural diagram of another detection circuit for the DC component of the voltage of the energy storage inverter provided by the embodiment of the present invention. Refer to Figure 1 and Figure 2 . Optionally, the first DC component detection unit 10 includes: a high-impedance differential detection subunit 101, a first filtering subunit 102, an amplification subunit 103, and a first biasing subunit 104;

[0089] The first input end of the high-impedance differential detection subunit 101 is connected to the phase voltage output end R, the second input end of the high-impedance differential detection subunit 101 is connected to the neutral line N, and the high-impedance differential detection subunit 101 is used to generate a first detection signal according to the phase voltage AC signal;

[0090] The first end of the first filtering subunit 102 is connected to the output end of the high-impedance differential detection subunit 101, and is used for filtering the alternating current signal in the first detection signal to generate a first filtered signal;

[0091] The input end of the amplification subunit 103 is connected to the second end of the first filtering subunit 102, and is used for amplifying the first filtered signal to generate a first amplified signal;

[0092] The input end of the first biasing subunit 104 is connected to the output end of the amplification subunit 103, and is used for lifting the zero voltage of the direct current signal in the first amplified signal to generate a first direct current voltage.

[0093] The high-impedance differential detection subunit 101 is used for performing high-impedance differential detection on the phase voltage alternating current signal to generate a first detection signal. The first filtering subunit 102 and each of the following filtering subunits can be first-order filtering or second-order filtering, and the first filtering subunit 102 can be RC filtering or LC filtering, or other software and other circuits capable of implementing the filtering function can also be used. This embodiment does not make specific limitations on this. The first filtering subunit 102 filters out the alternating current component in the first detection signal, and the remaining direct current component passes through and enters the amplification subunit 103. The amplification subunit 103 can be a proportional amplification circuit. The amplification subunit 103 proportionally amplifies the extracted voltage direct current component. After the proportional amplification process is completed, it enters the first biasing subunit 104, and the voltage direct current component is lifted to the bias voltage at zero point. The magnitude of the bias voltage is determined according to the voltage range acceptable to the control unit 13. Optionally, the bias voltage is equal to half of the sum of the upper limit value and the lower limit value of the voltage acceptable to the control unit 13. The first biasing subunit 104 is also used for adjusting the voltage so that the voltage output by itself meets the range allowed by the voltage level selection unit 12 and the input voltage of the control unit 13.

[0094] Figure 3 This is a schematic structural diagram of another detection circuit for the voltage direct current component of the energy storage inverter provided by the embodiment of the present invention. On the basis of the above embodiment, refer to Figure 1 and Figure 3 Optionally, the first direct current component detection unit 10 further includes: a voltage follower subunit 105 and a second filtering subunit 106;

[0095] The input end of the voltage follower subunit 105 is connected to the second end of the first filtering subunit 102, and is used for isolating the signal output from the output end of the voltage follower subunit 105 from the first filtered signal;

[0096] The first end of the second filtering subunit 106 is connected to the output end of the voltage follower subunit 105, and the second end of the second filtering subunit 106 is connected to the input end of the amplification subunit 103, and is used to filter out the AC signal in the signal output by the voltage follower subunit 105.

[0097] In this embodiment, the amplification subunit 103 is connected to the second end of the first filtering subunit 102 through the voltage follower subunit 105 and the second filtering subunit 106. The voltage follower subunit 105 can be a voltage follower, and the output end and the input end of the voltage follower subunit 105 are signal-isolated to protect the front-stage circuit from the influence of the rear-stage circuit. The second filtering subunit 106 is used to filter out the AC signal that is not completely filtered out in the first filtering subunit 102 again, so as to ensure that the AC signal is filtered out as much as possible, leaving the DC component. The filtering cut-off frequency of the first filtering subunit 102 is higher than the cut-off frequency of the second filtering subunit 106, that is, the first filtering subunit 102 filters out the AC signal greater than or equal to the first frequency threshold, and the second filtering subunit 106 filters out the AC signal greater than or equal to the second frequency threshold, and the first frequency threshold is greater than the second frequency threshold.

[0098] Continue to refer to Figure 1 and Figure 3 Optionally, the first DC component detection unit 10 further includes a first filtering clamping subunit 107, and the first filtering clamping subunit 107 is connected between the output end of the first biasing subunit and the first input end Y1 of the voltage level selection unit 12, and is used to filter out the AC signal in the first DC voltage and limit the first DC voltage within the first voltage.

[0099] The first filtering clamping subunit 107 has filtering and clamping functions, and is used to filter out the interference introduced during the transmission of the voltage DC component before entering the voltage level selection unit 12, and control the excessive voltage DC component to be less than or equal to the first voltage, so as to protect the subsequent voltage level selection unit 12 from being damaged.

[0100] Figure 4 This is a schematic structural diagram of another detection circuit for the voltage DC component of the energy storage inverter provided by the embodiment of the present invention. Refer to Figure 1 and Figure 4 Optionally, the second DC component detection unit 11 includes: a first-stage high-impedance detection subunit 111, a second-stage high-impedance detection subunit 112, a common-mode rejection subunit 113, a differential amplification subunit 114, and a second biasing subunit 115;

[0101] The first input terminal of the first - stage high - impedance detection sub - unit 111 is connected to the phase - voltage output terminal R, and the second input terminal of the first - stage high - impedance detection sub - unit 111 is connected to the neutral line. The first - stage high - impedance detection sub - unit 111 is used to filter out the AC signal in the phase - voltage AC signal, generate a first DC extraction signal, and limit the voltage of the first DC extraction signal within a second voltage;

[0102] The first input terminal of the second - stage high - impedance detection sub - unit 112 is connected to the first output terminal of the first - stage high - impedance detection sub - unit 111, and the second input terminal of the second - stage high - impedance detection sub - unit 112 is connected to the second output terminal of the first - stage high - impedance detection sub - unit 111. The second - stage high - impedance detection sub - unit 112 is used to filter out the AC signal in the first DC extraction signal, generate a second DC extraction signal, and limit the voltage of the second DC extraction signal within a third voltage;

[0103] The first terminal of the common - mode rejection sub - unit 113 is connected to the first output terminal of the second - stage high - impedance detection sub - unit, and the second terminal of the common - mode rejection sub - unit 113 is connected to the second output terminal of the second - stage high - impedance detection sub - unit. The common - mode rejection sub - unit 113 is used to filter out the common - mode signal in the second DC extraction signal;

[0104] The first input terminal of the differential - amplification sub - unit 114 is connected to the first output terminal of the second - stage high - impedance detection sub - unit 112, and the second input terminal of the differential - amplification sub - unit 114 is connected to the second output terminal of the second - stage high - impedance detection sub - unit 112. The differential - amplification sub - unit 114 is used to generate a second amplified signal according to the second DC extraction signal;

[0105] The input terminal of the second - bias sub - unit 115 is connected to the output terminal of the differential - amplification sub - unit 114, and is used to lift the zero - point voltage of the DC signal in the second amplified signal to generate a second DC voltage.

[0106] The first - stage high - impedance detection sub - unit 111 is used to detect the AC voltage signal output by the energy storage inverter. The detected AC voltage signal is converted into a low - voltage signal similar to DC by the first - stage high - impedance detection sub - unit 111 and then enters the second - stage high - impedance detection sub - unit 112. The second - stage high - impedance detection sub - unit 112 constitutes the second - stage high - impedance detection, filters out the AC signal in the first DC extraction signal at the same time, extracts the DC component, clamps the abnormal signal to the third voltage, and protects the subsequent circuit to prevent the subsequent circuit from being damaged due to over - voltage. The second DC extraction signal generated by the second - stage high - impedance detection sub - unit 112 enters the common - mode rejection sub - unit 113 after output. When there is a common - mode voltage in the detection circuit, it is derived through the common - mode rejection sub - unit 113 to prevent the excessive common - mode voltage from entering the subsequent circuit and causing damage to the subsequent circuit, resulting in abnormal detection accuracy or abnormal data. After the second DC extraction signal comes out of the common - mode rejection sub - unit 113, it enters the differential amplification sub - unit 114 for differential signal ratio amplification processing. The processed signal is lifted by the second bias sub - unit 115 to adjust the zero - point voltage to within the allowable range of the input voltage of the voltage level selection unit 12 and the control unit 13.

[0107] Figure 5 FIG. is a schematic structural diagram of another detection circuit for the DC component of the voltage of the energy storage inverter provided by the embodiment of the present invention. Refer to Figure 1 and Figure 5 Optionally, the second DC component detection unit 11 further includes: a second voltage follower sub - unit 116;

[0108] The first input end of the second voltage follower sub - unit 116 is connected to the first output end of the second - stage high - impedance detection sub - unit 112. The first output end of the second voltage follower sub - unit 116 is connected to the first input end of the differential amplification sub - unit 114. The second input end of the second voltage follower sub - unit 116 is connected to the second output end of the second - stage high - impedance detection sub - unit 112. The second output end of the second voltage follower sub - unit 116 is connected to the second input end of the differential amplification sub - unit 114. The second voltage follower sub - unit 116 is used to isolate the signal between the signal input to the first input end of the differential amplification sub - unit 114 and the signal output from the first output end of the second - stage high - impedance detection sub - unit 112, and isolate the signal between the signal input to the second input end of the differential amplification sub - unit 114 and the signal output from the second output end of the second - stage high - impedance detection sub - unit 112.

[0109] Continue to refer to Figure 1 and Figure 5, Optionally, the second DC component detection unit 11 further includes: a third filtering subunit 117 and a second filtering clamping subunit 118. The third filtering subunit 117 is connected between the differential amplification subunit 114 and the second biasing subunit 115, and is used to filter the second amplified signal output by the differential amplification subunit 114 to further filter out the AC signal. The second filtering clamping subunit 118 is connected between the output end of the second biasing subunit 115 and the second input terminal Y2 of the voltage level selection unit 12, and is used to filter out the AC signal in the second DC voltage and limit the second DC voltage within the first voltage. On the one hand, the second filtering clamping subunit 118 continues to filter out the AC signal in the signal output by the second biasing subunit 115. On the other hand, it clamps the abnormal signal input to the second input terminal Y2 of the voltage level selection unit 12 to the first voltage to prevent the voltage from being too large and damaging the voltage level selection unit 12.

[0110] Figure 6 is a schematic structural diagram of another detection circuit for the DC component of the energy storage inverter voltage provided by the embodiment of the present invention. Refer to Figure 1 and Figure 6 , Optionally, the detection circuit for the DC component of the energy storage inverter voltage further includes a third filtering clamping unit 14. The third filtering clamping subunit 14 is connected between the output terminal OUT of the voltage level selection unit 12 and the input terminal of the control unit 13, and is used to filter the voltage output by the voltage level selection unit 12 and limit the voltage input to the input terminal of the control unit 13 within the first voltage. The third filtering clamping subunit 14 filters the signal in the input control unit 13, and at the same time controls the voltage in the input control unit 13 to be less than or equal to the first voltage, restricting the excessive DC voltage component from entering the control unit 13 and causing damage to the control unit 13. Figure 6 In , the first DC component detection unit 10 includes: a high-impedance differential detection subunit 101, a first filtering subunit 102, a first voltage follower subunit 105, a second filtering subunit 106, an amplification subunit 103, a first biasing subunit 104, and a first filtering clamping subunit 107. The second DC component detection unit 11 includes: a first-stage high-impedance detection subunit 111, a second voltage follower subunit 116, a second-stage high-impedance detection subunit 112, a common-mode rejection subunit 113, a differential amplification subunit 114, a third filtering subunit 117, a second biasing subunit 115, and a second filtering clamping subunit 118.

[0111] Figure 7 is a schematic structural diagram of another detection circuit for the DC component of the energy storage inverter voltage provided by the embodiment of the present invention. Figure 7 is Figure 6 a specific circuit diagram in . Refer to Figure 6 and Figure 7, optionally, the high-impedance differential detection subunit 101 includes: a first resistor string, a second resistor string, a first clamping device, a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, a first operational amplifier U1, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a second capacitor C2;

[0112] The first resistor string includes at least two resistors connected in series. The first end of the first resistor string is connected to the phase voltage output terminal R. The second end of the first resistor string is connected to the first end of the first resistor R1. The second end of the first resistor R1 is connected to the first input terminal of the first operational amplifier U1. The second resistor R2, the third resistor R3, and the first capacitor C1 are connected in parallel between the first input terminal of the first operational amplifier U1 and the ground terminal GND.

[0113] The second resistor string includes at least two resistors connected in series. The first end of the second resistor string is connected to the neutral line N. The second end of the second resistor string is connected to the first end of the fourth resistor R4. The second end of the fourth resistor R4 is connected to the second input terminal of the first operational amplifier U1;

[0114] The first end of the fifth resistor R5 is connected to the second input terminal of the first operational amplifier U1. The second end of the fifth resistor R5 is connected to the ground terminal GND. The sixth resistor R6 and the second capacitor C2 are connected in parallel between the second input terminal of the first operational amplifier U1 and the output terminal of the first operational amplifier U1;

[0115] The first clamping device is connected between the second end of the first resistor string and the second end of the second resistor string. The first clamping device is used to limit the voltage between the second end of the first resistor string and the second end of the second resistor string within the first regulated voltage range.

[0116] The first resistor string includes a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35, a thirty-sixth resistor R36, and a thirty-seventh resistor R37 connected in series in sequence. The second resistor string includes a thirty-eighth resistor R38, a thirty-ninth resistor R39, a fortieth resistor R40, a forty-first resistor R41, a forty-second resistor R42, and a forty-third resistor R43 connected in series in sequence. The first resistor string, the first resistor R1, and the second resistor R2, or the first resistor string, the first resistor R1, and the third resistor R3 form a high-impedance detection path to prevent excessive potential from being input to the first input terminal of the first operational amplifier U1 and causing damage to the first operational amplifier U1. The second resistor string, the fourth resistor R4, and the fifth resistor R5 form another high-impedance detection path to prevent excessive potential from being input to the second input terminal of the first operational amplifier U1 and causing damage to the first operational amplifier U1. Among them, in this embodiment and the following embodiments, the first input terminal of each operational amplifier can be the positive terminal, and the second input terminal is the negative terminal, which will not be elaborated hereinafter. Among them, the signal U1 i output by the output terminal of the first operational amplifier U1 is U1 i = R6i * U1 i / (R2i + R4i), where R6i is the resistance value of the sixth resistor R6, U1 i is the DC component voltage value between the phase voltage output terminal R and the neutral line N, R2i is the resistance value of the second resistor string, and R4i is the resistance value of the fourth resistor R4. The first clamping device includes a first transient suppression diode T1 and a second transient suppression diode T2. The input terminal of the first transient suppression diode T1 is connected to the input terminal of the second transient suppression diode T2. The output terminal of the first transient suppression diode T1 is connected to the second terminal of the first resistor string. The output terminal of the second transient suppression diode T2 is connected to the second terminal of the second resistor string. The first clamping device limits the detection signal of the AC voltage signal input to the first operational amplifier U1 within the first regulated voltage range. Optionally, the first regulated voltage range is from -12V to 12V, ensuring that the abnormal voltage input to the first input terminal and the second input terminal of the first operational amplifier U1 does not exceed the voltage that the input port of the first operational amplifier U1 can withstand.

[0117] The first filtering sub-unit includes: a seventh resistor R7, a third capacitor C3, an eighth resistor R8, and a fourth capacitor C4;

[0118] The first terminal of the seventh resistor R7 is connected to the output terminal of the high-impedance differential detection sub-unit 101, specifically to the output terminal of the first operational amplifier U1. The second terminal of the seventh resistor R7 is connected to the first terminal of the third capacitor C3. The second terminal of the third capacitor C3 is connected to the ground terminal GND;

[0119] The first terminal of the eighth resistor R8 is connected to the second terminal of the seventh resistor R7. The second terminal of the eighth resistor R8 is connected to the first terminal of the fourth capacitor C4. The second terminal of the fourth capacitor C4 is connected to the ground terminal GND. The second terminal of the eighth resistor R8 is also connected to the input terminal of the amplification sub-unit 103.

[0120] Specifically, the seventh resistor R7, the third capacitor C3, the eighth resistor R8, and the fourth capacitor C4 form a second-order low-pass filter to filter out the AC signal, and the remaining DC voltage component enters the subsequent circuit.

[0121] The first voltage follower sub-unit 105 includes a fourth operational amplifier U4. The first input terminal of the fourth operational amplifier U4 is connected to the second terminal of the first filter sub-unit 102, specifically to the second terminal of the eighth resistor R8. The second input terminal of the fourth operational amplifier U4 is connected to the output terminal of the fourth operational amplifier U4. Specifically, the fourth operational amplifier U4 forms a voltage follower to buffer and isolate the signal input to the fourth operational amplifier U4 and the signal output by the fourth operational amplifier U4.

[0122] The second filter sub-unit 106 includes a fifteenth resistor R15, an eighth capacitor C8, a sixteenth resistor R16, and a ninth capacitor C9. The first terminal of the fifteenth resistor R15 is connected to the output terminal of the fourth operational amplifier U4. The second terminal of the fifteenth resistor R15 is connected to the first terminal of the eighth capacitor C8. The second terminal of the eighth capacitor C8 is connected to the ground terminal GND. The first terminal of the sixteenth resistor R16 is connected to the second terminal of the fifteenth resistor R15. The second terminal of the sixteenth resistor R16 is connected to the input terminal of the amplification sub-unit 103. The first terminal of the ninth capacitor C9 is connected to the second terminal of the sixteenth resistor R16. The second terminal of the ninth capacitor C9 is connected to the ground terminal GND. The fifteenth resistor R15, the eighth capacitor C8, the sixteenth resistor R16, and the ninth capacitor C9 form a second second-order low-pass filter circuit to filter out the AC signal that the first filter sub-unit 102 has not completely filtered out.

[0123] The amplification sub-unit 103 includes: a second operational amplifier U2, a ninth resistor R9, and a tenth resistor R10. The first input terminal of the second operational amplifier U2 serves as the input terminal of the amplification sub-unit 103 and is connected to the second terminal of the first filter sub-unit 102. When the first DC detection unit 10 further includes the first voltage follower sub-unit 105 and the second filter sub-unit 106, the first input terminal of the second operational amplifier U2 is connected to the second terminal of the sixteenth resistor R16. The first terminal of the ninth resistor R9 is connected to the second input terminal of the second operational amplifier U2. The second terminal of the ninth resistor R9 is connected to the ground terminal GND. The first terminal of the tenth resistor R10 is connected to the second input terminal of the second operational amplifier U2. The second terminal of the tenth resistor R10 is connected to the output terminal of the second operational amplifier U2. The output terminal of the second operational amplifier U2 is connected to the input terminal of the first bias sub-unit 104. The signal output by the second filter sub-unit 106 enters the non-inverting proportional amplification circuit to proportionally amplify the extracted DC voltage component. The proportional amplification circuit is composed of the second operational amplifier U2, the ninth resistor R9, and the tenth resistor R10. Among them, the amplification factor of the second operational amplifier U2 is equal to 1 + R10i / R9i, where R10i is the resistance value of the tenth resistor R10 and R9i is the resistance value of the ninth resistor.

[0124] The first bias sub-unit 104 includes: a third operational amplifier U3, an eleventh resistor R11, a twelfth resistor R12, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, a thirteenth resistor R13, and a fourteenth resistor R14;

[0125] The first end of the eleventh resistor R11 is connected to the output end of the amplification sub-unit 103, specifically to the output end of the second operational amplifier U2. The second end of the eleventh resistor R11 is connected to the second input end of the third operational amplifier U3. The twelfth resistor R12 and the fifth capacitor C5 are connected in parallel between the second input end and the output end of the third operational amplifier U3;

[0126] The first end of the sixth capacitor C6 is connected to the first power supply V1, and the second end of the sixth capacitor C6 is connected to the ground terminal GND. The first end of the thirteenth resistor R13 is connected to the first power supply VI, and the second end of the thirteenth resistor R13 is connected to the first input end of the third operational amplifier U3. The fourteenth resistor R14 and the seventh capacitor C7 are connected in parallel between the first input end of the third operational amplifier U3 and the ground terminal GND.

[0127] The sixth capacitor C6, the seventh capacitor C7, the thirteenth resistor R13, and the fourteenth resistor R14 constitute a bias voltage generation circuit for generating a bias voltage. In this embodiment, by way of example, the first power supply V1 provides a DC voltage of 3V, the minimum allowable voltage of the input port of the control unit 13 is 0V, and the maximum is 3V. Therefore, the bias voltage is equal to 1.5V, that is, the sixth capacitor C6, the seventh capacitor C7, the thirteenth resistor R13, and the fourteenth resistor R14 are used to generate a 1.5V voltage and input it to the first input end of the third operational amplifier U3. The output of the third operational amplifier U3 is U3i=(1 + R12i / R11i)×V0, where V0 is the bias voltage, R12i is the resistance value of the twelfth resistor R12, and R11i is the resistance value of the eleventh resistor R11. The signal output by the amplification sub-unit 103 enters the first bias sub-unit 104, raising the voltage DC component by 1.5V, and cooperating with the proportional amplification circuit for proportional amplification adjustment to adjust it within the allowable voltage range of the voltage level selection unit 12 and the input end of the control unit 13. The 1.5V bias and proportional amplification circuit is composed of the third operational amplifier U3, the eleventh resistor R11, the twelfth resistor R12, the fifth capacitor C5, the sixth capacitor C6, the seventh capacitor C7, the thirteenth resistor R13, and the fourteenth resistor R14, and is output to the subsequent circuit after passing through the 1.5V bias and proportional amplification circuit.

[0128] The first filter embedding sub-unit 107 includes a seventeenth resistor R17, a tenth capacitor C10, a first diode D1, and a second diode D2;

[0129] The first end of the seventeenth resistor R17 is connected to the output end of the first bias sub-unit 104, specifically to the output end of the third operational amplifier U3. The second end of the seventeenth resistor R17 is connected to the first input end Y1 of the voltage level selection unit 12. The first end of the tenth capacitor C10 is connected to the second end of the seventeenth resistor R17. The second end of the tenth capacitor C10 is connected to the ground terminal GND.

[0130] The first end of the first diode D1 is connected to the second end of the seventeenth resistor R17. The second end of the first diode D1 is connected to the first voltage V2. The first end of the second diode D2 is connected to the ground terminal GND. The second end of the second diode D2 is connected to the second end of the seventeenth resistor R17.

[0131] The seventeenth resistor R17 and the tenth capacitor C10 form a first-order low-pass filter circuit to process the interference introduced during the transmission of the DC voltage component and filter it out before it enters the voltage level selection unit 12. The abnormal DC voltage component is clamped to the first voltage, such as 3.3V, through the first diode D1 and the second diode D2 to protect the subsequent voltage level selection unit 12 from damage.

[0132] The first-stage high-impedance detection sub-unit 111 includes: a third resistor string, a fourth resistor string, an eleventh capacitor C11, and a second clamping device. The third resistor string includes at least two resistors connected in series. The fourth resistor string includes at least two resistors connected in series. The first end of the third resistor string is connected to the phase voltage output terminal R. The second end of the third resistor string is connected to the first input end of the second-stage high-impedance detection sub-unit 112. The first end of the fourth resistor string is connected to the neutral line N. The second end of the fourth resistor string is connected to the second input end of the second-stage high-impedance detection sub-unit 112. The eleventh capacitor C11 and the second clamping device are connected in parallel between the second end of the third resistor string and the second end of the fourth resistor string. The second clamping device is used to limit the first DC extraction signal within the second voltage.

[0133] The second - stage high - impedance detection sub - unit 112 includes: a fifth resistor string, a sixth resistor string, a twelfth capacitor C12, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty - first resistor R21, a thirteenth capacitor C13, a fourteenth capacitor C14, a fifteenth capacitor C15, and a third clamping device. The fifth resistor string includes at least two resistors connected in series, and the sixth resistor string includes at least two resistors connected in series. The first end of the fifth resistor string is connected to the first output end of the first - stage high - impedance detection sub - unit 111. The second end of the fifth resistor string is connected to the first end of the eighteenth resistor R18. The nineteenth resistor R19 and the twelfth capacitor C12 are connected in parallel between the second end of the eighteenth resistor R18 and the ground terminal GND. The second end of the eighteenth resistor R18 is also connected to the first input end of the differential amplification sub - unit 114. When the second DC component detection unit includes the second voltage - following sub - unit 116, the second end of the eighteenth resistor R18 is connected to the first input end of the differential amplification sub - unit 114 through the second voltage - following sub - unit 116. The first end of the sixth resistor string is connected to the second output end of the first - stage high - impedance detection sub - unit 111. The second end of the sixth resistor string is connected to the first end of the twentieth resistor R20. The twenty - first resistor R21 and the thirteenth capacitor C13 are connected in parallel between the second end of the twentieth resistor R20 and the ground terminal GND. The second end of the twentieth resistor R20 is also connected to the second input end of the differential amplification sub - unit 114. When the second DC component detection unit includes the second voltage - following sub - unit, the second end of the twentieth resistor R20 is connected to the second input end of the differential amplification sub - unit 114 through the second voltage - following sub - unit 116. The fourteenth capacitor C14 is connected in parallel between the second end of the fifth resistor string and the second end of the sixth resistor string. The fifteenth capacitor C15 and the third clamping device are connected in parallel between the second end of the eighteenth resistor R18 and the second end of the twentieth resistor R20. The third clamping device is used to limit the voltage of the second DC extraction signal within the third voltage.

[0134] Specifically, the third resistor string includes a forty-fourth resistor R44, a forty-fifth resistor R45, and a forty-sixth resistor R46 connected in series in sequence. The fourth resistor string includes a forty-seventh resistor R47, a forty-eighth resistor R48, and a forty-ninth resistor R49 connected in series in sequence. The first clamping device includes a third transient suppression diode T3 and a fourth transient suppression diode T4. The input end of the third transient suppression diode T3 is connected to the input end of the fourth transient suppression diode T4. The output end of the third transient suppression diode T3 is connected to the second end of the third resistor string, that is, the second end of the forty-sixth resistor R46. The output end of the fourth transient suppression diode T4 is connected to the second end of the fourth resistor string, that is, the second end of the forty-ninth resistor R49. The second clamping device is used to control the voltage difference between the second end of the third resistor string and the second end of the fourth resistor string to be less than or equal to the second voltage. The third resistor string and the fourth resistor string constitute a first-level high-resistance detection to detect the AC voltage signal output by the energy storage inverter. The detected signal enters the first-level clamping protection and filtering circuit composed of the eleventh capacitor C11 and the second clamping device, and converts the detected AC voltage signal into a low-voltage signal approximate to DC, and then enters the second-level high-resistance detection sub-unit 112.

[0135] The fourth resistor string includes a fiftieth resistor R50, a fifty-first resistor R51, and a fifty-second resistor R52 connected in series in sequence. The fifth resistor string includes a fifty-third resistor R53, a fifty-fourth resistor R54, and a fifty-fifth resistor R55 connected in series in sequence. The third clamping device includes a fifth transient suppression diode T5 and a sixth transient suppression diode T6. The input end of the fifth transient suppression diode T5 is connected to the input end of the sixth transient suppression diode T6. The output end of the fifth transient suppression diode T5 is connected to the second end of the eighteenth resistor R18. The output end of the sixth transient suppression diode T6 is connected to the second end of the twentieth resistor R20. The third clamping device is used to control the voltage difference between the second end of the twentieth resistor R20 and the second end of the eighteenth resistor R18 to be less than or equal to the third voltage. The fifth resistor string and the sixth resistor string constitute a two-stage high-impedance detection. The nineteenth resistor R19, the twelfth capacitor C12, the twenty-first resistor R21, and the thirteenth capacitor C13 cooperate with the fiftieth resistor R50, the fifty-first resistor R51, the fifty-second resistor R52, the eighteenth resistor R18, the fifty-third resistor R53, the fifty-fourth resistor R54, the fifty-fifth resistor R55, and the twentieth resistor R20 to generate a voltage division signal, extract the DC component in the AC voltage signal, clamp the abnormal signal to the third voltage by means of the fifth transient suppression diode T5 and the sixth transient suppression diode T6, and protect the subsequent circuit to prevent the subsequent circuit from being damaged due to overvoltage. Optionally, the second voltage is equal to 12V and the third voltage is equal to 3.3V. The cut-off frequency of the filtering of the first-stage high-impedance detection sub-unit 111 is higher than the cut-off frequency of the filtering of the second-stage high-impedance detection sub-unit 112, ensuring that the useful DC component signal passes through intact, and at the same time effectively filtering and clamping the high-frequency interference signal to prevent the subsequent circuit from being damaged by excessive voltage.

[0136] The common-mode rejection sub-unit 113 includes: a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6. The first end of the third diode D3 is connected to the first output end of the second-stage high-impedance detection sub-unit 112. The second end of the third diode D3 is connected to the fourth voltage V3. The first end of the fourth diode D4 is connected to the fifth voltage V4. The second end of the fourth diode D4 is connected to the first output end of the second-stage high-impedance detection sub-unit 112. The first end of the fifth diode D5 is connected to the second output end of the second-stage high-impedance detection sub-unit 112. The second end of the fifth diode D5 is connected to the fourth voltage V3. The first end of the sixth diode D6 is connected to the fifth voltage V4. The second end of the sixth diode D6 is connected to the second output end of the second-stage high-impedance detection sub-unit 112. The fourth voltage V3 and the fifth voltage V4 are inverse-phase voltages.

[0137] Optionally, the fourth voltage V3 is +5V and the fifth voltage V4 is -5V. Since the DC signal detected by the second DC component detection unit is relatively weak, even a small interference will have a greater impact on the detected DC component of the voltage. Therefore, a common-mode suppression sub-unit 113 needs to be set up to filter out the interference of the common-mode signal. When there is a common-mode voltage, it is led to the ground terminal GND through the common-mode suppression sub-unit, preventing the excessive common-mode voltage from entering the subsequent second voltage follower sub-unit 116, resulting in the loss of linearity of the subsequent operational amplifier circuit or damage to the operational amplifier, thereby causing abnormal detection accuracy or abnormal data.

[0138] The second voltage follower sub-unit 116 includes: a seventh operational amplifier U7 and an eighth operational amplifier U8;

[0139] The first input terminal of the seventh operational amplifier U7 is connected to the first output terminal of the second-stage high-impedance detection sub-unit 112, specifically to the second terminal of the eighteenth resistor R18. The second input terminal of the seventh operational amplifier U7 is connected to the output terminal of the seventh operational amplifier U7. The output terminal of the seventh operational amplifier U7 is connected to the first input terminal of the differential amplification sub-unit 114;

[0140] The first input terminal of the eighth operational amplifier U8 is connected to the second output terminal of the second-stage high-impedance detection sub-unit 112, specifically to the second terminal of the twentieth resistor R20. The second input terminal of the eighth operational amplifier U8 is connected to the output terminal of the eighth operational amplifier U8. The output terminal of the eighth operational amplifier U8 is connected to the second input terminal of the differential amplification sub-unit 114.

[0141] The differential amplification sub-unit 114 includes a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a sixteenth capacitor C16, a fifth operational amplifier U5, a twenty-fifth resistor R25, a twenty-sixth resistor R26, a twenty-seventh resistor R27, and a seventeenth capacitor C17;

[0142] The first terminal of the twenty-second resistor R22 is connected to the first output terminal of the second-stage high-impedance detection sub-unit 112 and can be connected to the eighteenth resistor R18 through the second voltage follower sub-unit 116. The second terminal of the twenty-second resistor R22 is connected to the first input terminal of the fifth operational amplifier U5. The twenty-third resistor R23, the twenty-fourth resistor R24, and the sixteenth capacitor C16 are connected in parallel between the first input terminal of the fifth operational amplifier U5 and the ground terminal GND. The first terminal of the twenty-fifth resistor R25 is connected to the second output terminal of the second-stage high-impedance detection sub-unit 112. The second terminal of the twenty-fifth resistor R25 is connected to the second input terminal of the fifth operational amplifier U5. The twenty-sixth resistor R26 is connected between the second input terminal of the fifth operational amplifier U5 and the ground terminal GND. The twenty-seventh resistor R27 and the seventeenth capacitor C17 are connected in parallel between the second input terminal of the fifth operational amplifier U5 and the output terminal of the fifth operational amplifier U5.

[0143] Specifically, the differential amplification sub-unit 114 is used to perform differential signal proportional amplification processing. The amplification ratio of the fifth operational amplifier U5 is equal to (1 + R27i / R25i), where R27i is the resistance value of the twenty-seventh resistor, and R25i is the resistance value of the twenty-fifth resistor R25.

[0144] Optionally, the second DC component detection unit 11 further includes: a twenty-ninth resistor R29 and a nineteenth capacitor C19. The first end of the twenty-ninth resistor R29 is connected to the output end of the differential amplification sub-unit 114. The second end of the twenty-ninth resistor R29 is connected to the input end of the second bias sub-unit 115. The first end of the nineteenth capacitor C19 is connected to the second end of the twenty-ninth resistor R29. The second end of the nineteenth capacitor C19 is connected to the ground terminal GND.

[0145] The twenty-ninth resistor R29 and the nineteenth capacitor C19 form a first-order filter circuit to perform first-order RC filtering, and the filtered signal enters the second bias sub-unit 115.

[0146] The second bias sub-unit 115 includes: a sixth operational amplifier U6, a twenty-eighth resistor R18, and an eighteenth capacitor C18;

[0147] The first input terminal of the sixth operational amplifier U6 is connected to the output end of the differential amplification sub-unit 114, which can be connected to the output end of the differential amplification sub-unit 114 through the twenty-ninth resistor R29. The second input terminal of the sixth operational amplifier U6 is connected to the output end of the sixth operational amplifier U6. The first end of the twenty-eighth resistor R28 is connected to the first power supply V1. The second end of the twenty-eighth resistor R28 is connected to the first input terminal of the sixth operational amplifier U6. The first end of the eighteenth capacitor C18 is connected to the first end of the twenty-eighth resistor R28. The second end of the eighteenth capacitor C18 is connected to the ground terminal GND.

[0148] The second bias sub-unit 115 is used to generate a bias voltage, and the difference between its output terminal and input terminal is equal to the bias voltage. In this embodiment, the bias voltage is exemplarily set to 1.5V. The filtered signal passes through a 1.5V bias circuit to raise the DC component voltage by 1.5V, meeting the voltage input range and accuracy requirements of the input terminal of the control unit 13.

[0149] The second filter embedding sub-unit 118 includes: a thirtieth resistor R30, a twentieth capacitor C20, a seventh diode D7, and an eighth diode D8;

[0150] The first end of the thirtieth resistor R30 is connected to the output end of the second bias sub-unit 115, specifically to the output end of the sixth operational amplifier U6. The second end of the thirtieth resistor R30 is connected to the first end of the twentieth capacitor C20. The second end of the twentieth capacitor C20 is connected to the ground terminal GND. The second end of the thirtieth resistor R30 is connected to the second input terminal Y2 of the voltage level selection unit 12;

[0151] The first end of the seventh diode D7 is connected to the second input terminal Y2 of the voltage level selection unit 12. The second end of the seventh diode D7 is connected to the first voltage V2. The first end of the eighth diode D8 is connected to the ground terminal GND. The second end of the eighth diode D8 is connected to the second input terminal Y2 of the voltage level selection unit 12.

[0152] The thirtieth resistor R30 and the twentieth capacitor C20 form a first-order low-pass filter circuit for filtering the signal output by the second bias sub-unit 115. The seventh diode D7 and the eighth diode D8 form a clamping circuit for limiting the voltage input to the second input terminal Y2 of the voltage level selection unit 12 within the first voltage. The signal output by the second bias sub-unit 115 enters the second filter clamping sub-unit 118 to prevent the DC component signal of the voltage from being too large, causing the input current of the subsequent voltage level selection unit 12 to be too large and clamping and protecting the excessive DC component of the input voltage to prevent overvoltage damage to the voltage level selection unit 12. Subsequently, the DC component of the voltage enters the voltage level selection unit 12.

[0153] The third filter clamping unit 14 includes: the thirty-first resistor R31, the twenty-first capacitor C21, the ninth diode D9, and the tenth diode D10;

[0154] The first end of the thirty-first resistor R31 is connected to the output terminal OUT of the voltage level selection unit 12. The second end of the thirty-first resistor R31 is connected to the input terminal of the control unit 13. The first end of the twenty-first capacitor C21 is connected to the second end of the thirty-first resistor R31. The second end of the twenty-first capacitor C21 is connected to the ground terminal GND;

[0155] The first end of the ninth diode D9 is connected to the input terminal of the control unit 13. The second end of the ninth diode D9 is connected to the first voltage V2. The first end of the tenth diode D10 is connected to the ground terminal GND. The second end of the tenth diode D10 is connected to the input terminal of the control unit 13.

[0156] The thirty-first resistor R31 and the twenty-first capacitor C21 form a first-order low-pass filter circuit for filtering the signal output by the voltage level selection unit 12. The ninth diode D9 and the tenth diode D10 form a clamping circuit for controlling the voltage input to the control unit 13 to be less than or equal to the first voltage.

[0157] The strobe terminals of the voltage level selection unit 12 include a first sub-strobe terminal A and a second sub-strobe terminal B. In an optional embodiment, when the control unit 13 sends a first strobe signal to the strobe terminal, the control voltage level selection unit 12 outputs a first DC voltage to the control unit 13. When sending a second strobe signal to the strobe terminal, the control voltage level selection unit 12 outputs a second DC voltage to the control unit 13. The first strobe signal can be 10, that is, the potential received by the first sub-strobe terminal A is "1" and the potential received by the second sub-strobe terminal B is "0". The second strobe signal can be 01, that is, the potential received by the first sub-strobe terminal A is "0" and the potential received by the second sub-strobe terminal B is "1".

[0158] Adopt Figure 7 Multiple experiments are carried out using the circuit shown, and the test data of the detection circuit of the DC component of the energy storage inverter voltage shown in Table 1 are obtained.

[0159] Table 1 Test data of the detection circuit of the DC component of the energy storage inverter voltage

[0160]

[0161]

[0162] Closed-loop control is performed on the DC component of the AC voltage. When the DC voltage component is greater than 1V, the first DC component detection unit is used, and the detection control effect is very good. When the DC component is less than or equal to 1V, the first DC component detection unit cannot well meet the accuracy and control requirements of the DC component, and the second DC component detection unit needs to be used to process the relatively small DC component signal to meet the control requirements of the very small DC component.

[0163] In this embodiment, the first DC component detection unit detects the DC component in the signal output by the energy storage inverter in the form of sampling first and then filtering. The second DC component detection unit detects the DC component in the signal output by the energy storage inverter in the form of filtering first and then sampling, and two-stage high-resistance detection is adopted, which can reduce the detection deviation and is more suitable for the detection of weak DC component signals.

[0164] Each device for realizing the clamping function in this embodiment can adopt a transient voltage suppression diode (TVS tube), or a voltage stabilizing tube, or other voltage clamping devices or circuits with the same function. Whether it is the first bias sub-unit 104 or the second bias sub-unit 115, a 1.5V bias can be used or adjusted to other bias voltage circuits in cooperation with a proportional circuit, such as adjusting the bias voltage to 1V, etc.

[0165] It should be understood that the various forms of processes shown above can be used, with steps reordered, added or deleted. For example, the steps recited in the present invention can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0166] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A detection circuit for a DC component of a voltage of an energy storage inverter, characterized in that: The energy storage inverter includes at least one phase voltage output terminal, the detection circuit of the DC component of the energy storage inverter voltage includes a DC component detection module corresponding to the phase voltage output terminal of the energy storage inverter, and the DC component detection module includes: a first DC component detection unit, a second DC component detection unit, a voltage level selection unit and a control unit; The first DC component detection unit is connected to the phase voltage output terminal and is used to generate a first DC voltage according to the input phase voltage AC signal; The second DC component detection unit is connected to the phase voltage output terminal and is used to generate a second DC voltage according to the connected phase voltage AC signal; The output terminal of the control unit is connected to the gate terminal of the voltage level selection unit, and is used to output a gate signal to the voltage level selection unit; The first input end of the voltage level selection unit is connected to the first DC component detection unit, the second input end of the voltage level selection unit is connected to the second DC component detection unit, and the output end of the voltage level selection unit is connected to the input end of the control unit, for outputting one of the first DC voltage or the second DC voltage to the control unit according to the selection signal; Among them, the acceptable voltage of the first DC component detection unit is greater than or equal to the first voltage threshold and less than or equal to the second voltage threshold, the acceptable voltage of the second DC component detection unit is greater than or equal to the third voltage threshold and less than or equal to the fourth voltage threshold, the fourth voltage threshold is less than the second voltage threshold, and the third voltage threshold is greater than the first voltage threshold.

2. The detection circuit of the DC component of the energy storage inverter voltage according to claim 1, characterized in that: The first DC component detection unit includes: a high-resistance differential detection subunit, a first filtering subunit, an amplifying subunit, and a first biasing subunit; The first input end of the high-resistance differential detection subunit is connected to the phase voltage output end, the second input end of the high-resistance differential detection subunit is connected to the neutral line, and the high-resistance differential detection subunit is used to generate a first detection signal according to the phase voltage AC signal; The first end of the first filtering subunit is connected to the output end of the high-resistance differential detection subunit, and is used to filter out the AC signal in the first detection signal to generate a first filtering signal; The input end of the amplifying subunit is connected to the second end of the first filtering subunit, and is used to amplify the first filtered signal to generate a first amplified signal; The input end of the first bias subunit is connected to the output end of the amplifying subunit, and is used to raise the zero point voltage of the DC signal in the first amplified signal to generate the first DC voltage.

3. The detection circuit of the DC component of the energy storage inverter voltage according to claim 2, characterized in that: The high-resistance differential detection subunit includes: a first resistor string, a second resistor string, a first clamping device, a first resistor, a second resistor, a third resistor, a first capacitor, a first operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor and a second capacitor; The first resistor string includes at least two resistors connected in series, a first end of the first resistor string is connected to the phase voltage output end, a second end of the first resistor string is connected to a first end of the first resistor, a second end of the first resistor is connected to a first input end of the first operational amplifier, and the second resistor, the third resistor and the first capacitor are connected in parallel between the first input end of the first operational amplifier and a ground end; The second resistor string includes at least two resistors connected in series, a first end of the second resistor string is connected to the neutral line, a second end of the second resistor string is connected to a first end of the fourth resistor, and a second end of the fourth resistor is connected to a second input end of the first operational amplifier; The first end of the fifth resistor is connected to the second input end of the first operational amplifier, the second end of the fifth resistor is connected to the ground end, and the sixth resistor and the second capacitor are connected in parallel between the second input end of the first operational amplifier and the output end of the first operational amplifier; The first clamping device is connected between the second end of the first resistor string and the second end of the second resistor string, and the first clamping device is used to limit the voltage between the second end of the first resistor string and the second end of the second resistor string to a first voltage regulation range; The first filtering subunit includes: a seventh resistor, a third capacitor, an eighth resistor and a fourth capacitor; The first end of the seventh resistor is connected to the output end of the high-resistance differential detection subunit, the second end of the seventh resistor is connected to the first end of the third capacitor, and the second end of the third capacitor is connected to the ground end; The first end of the eighth resistor is connected to the second end of the seventh resistor, the second end of the eighth resistor is connected to the first end of the fourth capacitor, the second end of the fourth capacitor is connected to the ground end, and the second end of the eighth resistor is also connected to the input end of the amplifying subunit; The amplifying subunit comprises: a second operational amplifier, a ninth resistor and a tenth resistor; The first input terminal of the second operational amplifier is connected to the second terminal of the first filtering subunit, the first end of the ninth resistor is connected to the second input terminal of the second operational amplifier, the second end of the ninth resistor is connected to the ground terminal, the first end of the tenth resistor is connected to the second input terminal of the second operational amplifier, the second end of the tenth resistor is connected to the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the input terminal of the first biasing subunit; The first bias subunit includes: a third operational amplifier, an eleventh resistor, a twelfth resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, a thirteenth resistor and a fourteenth resistor; The first end of the eleventh resistor is connected to the output end of the amplifying subunit, the second end of the eleventh resistor is connected to the second input end of the third operational amplifier, and the twelfth resistor and the fifth capacitor are connected in parallel between the second input end of the third operational amplifier and the output end of the third operational amplifier; The first end of the sixth capacitor is connected to the first power supply, the second end of the sixth capacitor is connected to the ground terminal, the first end of the thirteenth resistor is connected to the first power supply, the second end of the thirteenth resistor is connected to the first input terminal of the third operational amplifier, and the fourteenth resistor and the seventh capacitor are connected in parallel between the first input terminal of the third operational amplifier and the ground terminal.

4. The detection circuit of the DC component of the energy storage inverter voltage according to claim 2, characterized in that: The first DC component detection unit further includes: a first voltage follower subunit and a second filter subunit; The input end of the first voltage follower subunit is connected to the second end of the first filtering subunit, and is used to perform signal isolation between the signal outputted from the output end of the voltage follower subunit and the first filtered signal; The first end of the second filtering subunit is connected to the output end of the first voltage follower subunit, and the second end of the second filtering subunit is connected to the input end of the amplifying subunit, for filtering out the AC signal in the signal output by the first voltage follower subunit.

5. The detection circuit of the DC component of the energy storage inverter voltage according to claim 4, characterized in that: The first voltage follower subunit includes a fourth operational amplifier, a first input terminal of the fourth operational amplifier is connected to the second terminal of the first filtering subunit, and a second input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier; The second filtering subunit includes a fifteenth resistor, an eighth capacitor, a sixteenth resistor and a ninth capacitor, the first end of the fifteenth resistor is connected to the output end of the fourth operational amplifier, the second end of the fifteenth resistor is connected to the first end of the eighth capacitor, the second end of the eighth capacitor is connected to the ground end, the first end of the sixteenth resistor is connected to the second end of the fifteenth resistor, the second end of the sixteenth resistor is connected to the input end of the amplifying subunit, the first end of the ninth capacitor is connected to the second end of the sixteenth resistor, and the second end of the ninth capacitor is connected to the ground end.

6. The detection circuit of the DC component of the energy storage inverter voltage according to claim 2, characterized in that: The first DC component detection unit also includes a first filter embedding subunit, which is connected between the output end of the first bias subunit and the first input end of the voltage level selection unit, and is used to filter out the AC signal in the first DC voltage and limit the first DC voltage to a first voltage.

7. The detection circuit of the DC component of the energy storage inverter voltage according to claim 6, characterized in that: The first filter clamping subunit includes a seventeenth resistor, a tenth capacitor, a first diode and a second diode; The first end of the seventeenth resistor is connected to the output end of the first bias subunit, the second end of the seventeenth resistor is connected to the first input end of the voltage level selection unit, the first end of the tenth capacitor is connected to the second end of the seventeenth resistor, and the second end of the tenth capacitor is connected to the ground end; The first end of the first diode is connected to the second end of the seventeenth resistor, the second end of the first diode is connected to a first voltage, the first end of the second diode is connected to the ground end, and the second end of the second diode is connected to the second end of the seventeenth resistor.

8. The detection circuit of the DC component of the energy storage inverter voltage according to claim 1, characterized in that: The second DC component detection unit includes: a first-stage high-resistance detection subunit, a second-stage high-resistance detection subunit, a common-mode suppression subunit, a differential amplification subunit, and a second bias subunit; The first input terminal of the first-stage high-resistance detection subunit is connected to the phase voltage output terminal, the second input terminal of the first-stage high-resistance detection subunit is connected to the neutral line, the first-stage high-resistance detection subunit is used to filter out the AC signal in the phase voltage AC signal, generate a first DC extraction signal, and limit the voltage of the first DC extraction signal to a second voltage; The first input end of the second-stage high-resistance detection subunit is connected to the first output end of the first-stage high-resistance detection subunit, the second input end of the second-stage high-resistance detection subunit is connected to the second output end of the first-stage high-resistance detection subunit, the second-stage high-resistance detection subunit is used to filter out the AC signal in the first DC extraction signal, generate a second DC extraction signal, and limit the voltage of the second DC extraction signal to a third voltage; The first end of the common mode suppression subunit is connected to the first output end of the second-stage high-impedance detection subunit, the second end of the common mode suppression subunit is connected to the second output end of the second-stage high-impedance detection subunit, and the common mode suppression subunit is used to filter out the common mode signal in the second DC extraction signal; The first input end of the differential amplifier subunit is connected to the first output end of the second-stage high-resistance detection subunit, the second input end of the differential amplifier subunit is connected to the second output end of the second-stage high-resistance detection subunit, and the differential amplifier subunit is used to generate a second amplified signal according to the second DC extraction signal; The input end of the second bias subunit is connected to the output end of the differential amplifier subunit, and is used to raise the zero point voltage of the DC signal in the second amplified signal to generate a second DC voltage.

9. The detection circuit of the DC component of the energy storage inverter voltage according to claim 8, characterized in that: The first-level high-resistance detection subunit includes: a third resistor string, a fourth resistor string, an eleventh capacitor, and a second embedded device, the third resistor string includes at least two resistors connected in series, the fourth resistor string includes at least two resistors connected in series, a first end of the third resistor string is connected to a phase voltage output end, a second end of the third resistor string is connected to a first input end of the second-level high-resistance detection subunit, a first end of the fourth resistor string is connected to the neutral line, a second end of the fourth resistor string is connected to a second input end of the second-level high-resistance detection subunit, and the eleventh capacitor and the second embedded device are connected in parallel between the second end of the third resistor string and the second end of the fourth resistor string; The second-level high-resistance detection subunit includes: a fifth resistor string, a sixth resistor string, a twelfth capacitor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a thirteenth capacitor, a fourteenth capacitor, a fifteenth capacitor and a third embedded device, the fifth resistor string includes at least two resistors connected in series, the sixth resistor string includes at least two resistors connected in series, a first end of the fifth resistor string is connected to a first output end of the first-level high-resistance detection subunit, a second end of the fifth resistor string is connected to a first end of the eighteenth resistor, the nineteenth resistor and the twelfth capacitor are connected in parallel between the second end of the eighteenth resistor and the ground terminal, and the second end of the eighteenth resistor is also connected to the ground terminal. connected to the first input terminal of the differential amplifier subunit, the first end of the sixth resistor string is connected to the second output terminal of the first-stage high-resistance detection subunit, the second end of the sixth resistor string is connected to the first end of the twentieth resistor, the twenty-first resistor and the thirteenth capacitor are connected in parallel between the second end of the twentieth resistor and the ground terminal, the second end of the twentieth resistor is also connected to the second input terminal of the differential amplifier subunit, the fourteenth capacitor is connected in parallel between the second end of the fifth resistor string and the second end of the sixth resistor string, the fifteenth capacitor and the third clamping device are connected in parallel between the second end of the eighteenth resistor and the second end of the twentieth resistor; The common mode suppression subunit comprises: a third diode, a fourth diode, a fifth diode and a sixth diode, wherein the first end of the third diode is connected to the first output end of the second-stage high-resistance detection subunit, the second end of the third diode is connected to the fourth voltage, the first end of the fourth diode is connected to the fifth voltage, the second end of the fourth diode is connected to the first output end of the second-stage high-resistance detection subunit, the first end of the fifth diode is connected to the second output end of the second-stage high-resistance detection subunit, the second end of the fifth diode is connected to the fourth voltage, the first end of the sixth diode is connected to the fifth voltage, the second end of the sixth diode is connected to the second output end of the second-stage high-resistance detection subunit, and the fourth voltage and the fifth voltage are mutually inverse voltages; The differential amplifier subunit includes a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a sixteenth capacitor, a fifth operational amplifier, a twenty-fifth resistor, a twenty-sixth resistor, a twenty-seventh resistor and a seventeenth capacitor; The first end of the twenty-second resistor is connected to the first output end of the second-stage high-resistance detection subunit, the second end of the twenty-second resistor is connected to the first input end of the fifth operational amplifier, the twenty-third resistor, the twenty-fourth resistor and the sixteenth capacitor are connected in parallel between the first input end and the ground end of the fifth operational amplifier, the first end of the twenty-fifth resistor is connected to the second output end of the second-stage high-resistance detection subunit, the second end of the twenty-fifth resistor is connected to the second input end of the fifth operational amplifier, the twenty-sixth resistor is connected between the second input end of the fifth operational amplifier and the ground end, and the twenty-seventh resistor and the seventeenth capacitor are connected in parallel between the second input end of the fifth operational amplifier and the output end of the fifth operational amplifier; The second bias subunit includes: a sixth operational amplifier, a twenty-eighth resistor and an eighteenth capacitor; The first input terminal of the sixth operational amplifier is connected to the output terminal of the differential amplifier subunit, the second input terminal of the sixth operational amplifier is connected to the output terminal of the sixth operational amplifier, the first end of the twenty-eighth resistor is connected to the first power supply, the second end of the twenty-eighth resistor is connected to the first input terminal of the sixth operational amplifier, the first end of the eighteenth capacitor is connected to the first end of the twenty-eighth resistor, and the second end of the eighteenth capacitor is connected to the ground terminal.

10. The detection circuit of the DC component of the energy storage inverter voltage according to claim 8, characterized in that: The second DC component detection unit further includes: a second voltage follower subunit; The first input terminal of the second voltage follower subunit is connected to the first output terminal of the second-stage high-resistance detection subunit, the first output terminal of the second voltage follower subunit is connected to the first input terminal of the differential amplifier subunit, the second input terminal of the second voltage follower subunit is connected to the second output terminal of the second-stage high-resistance detection subunit, the second output terminal of the second voltage follower subunit is connected to the second input terminal of the differential amplifier subunit, and the second voltage follower subunit is used to isolate the signal between the first input terminal of the differential amplifier subunit and the signal output from the first output terminal of the second-stage high-resistance detection subunit, and to isolate the signal between the second input terminal of the differential amplifier subunit and the signal output from the second output terminal of the second-stage high-resistance detection subunit.

11. The detection circuit of the DC component of the energy storage inverter voltage according to claim 10, characterized in that: The second voltage follower subunit includes: a seventh operational amplifier and an eighth operational amplifier; The first input terminal of the seventh operational amplifier is connected to the first output terminal of the second-stage high-impedance detection subunit, the second input terminal of the seventh operational amplifier is connected to the output terminal of the seventh operational amplifier, and the output terminal of the seventh operational amplifier is connected to the first input terminal of the differential amplifier subunit; The first input terminal of the eighth operational amplifier is connected to the second output terminal of the second-stage high-impedance detection subunit, the second input terminal of the eighth operational amplifier is connected to the output terminal of the eighth operational amplifier, and the output terminal of the eighth operational amplifier is connected to the second input terminal of the differential amplifier subunit.

12. The detection circuit of the DC component of the energy storage inverter voltage according to claim 8, characterized in that: The second DC component detection unit also includes: a twenty-ninth resistor and a nineteenth capacitor, the first end of the twenty-ninth resistor is connected to the output end of the differential amplifier subunit, the second end of the twenty-ninth resistor is connected to the input end of the second bias subunit, the first end of the nineteenth capacitor is connected to the second end of the twenty-ninth resistor, and the second end of the nineteenth capacitor is connected to the ground end.

13. The detection circuit of the DC component of the energy storage inverter voltage according to claim 8, characterized in that: The second DC component detection unit also includes: a second filtering and clamping subunit, which is connected between the output end of the second biasing subunit and the second input end of the voltage level selection unit, and is used to filter out the AC signal in the second DC voltage and limit the second DC voltage to the first voltage.

14. The detection circuit of the DC component of the energy storage inverter voltage according to claim 13, characterized in that: The second filter embedding subunit includes: a 30th resistor, a 20th capacitor, a 7th diode and an 8th diode; A first end of the 30th resistor is connected to the output end of the second bias subunit, a second end of the 30th resistor is connected to the first end of the 20th capacitor, a second end of the 20th capacitor is connected to the ground end, and a second end of the 30th resistor is connected to the second input end of the voltage level selection unit; The first end of the seventh diode is connected to the second input end of the voltage level selection unit, the second end of the seventh diode is connected to the first voltage, the first end of the eighth diode is connected to the ground end, and the second end of the eighth diode is connected to the second input end of the voltage level selection unit.

15. The detection circuit of the DC component of the energy storage inverter voltage according to claim 1, characterized in that: It also includes a third filtering clamping unit, which is connected between the output end of the voltage level selection unit and the input end of the control unit, and is used to filter the voltage output by the voltage level selection unit and limit the voltage input to the input end of the control unit within the first voltage.

16. The detection circuit of the DC component of the energy storage inverter voltage according to claim 15, characterized in that: The third filtering clamping unit includes: a thirty-first resistor, a twenty-first capacitor, a ninth diode and a tenth diode; A first end of the thirty-first resistor is connected to the output end of the voltage level selection unit, a second end of the thirty-first resistor is connected to the input end of the control unit, a first end of the twenty-first capacitor is connected to the second end of the thirty-first resistor, and a second end of the twenty-first capacitor is connected to the ground end; The first end of the ninth diode is connected to the input end of the control unit, the second end of the ninth diode is connected to the first voltage, the first end of the tenth diode is connected to the ground end, and the second end of the tenth diode is connected to the input end of the control unit.

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