Detection circuit for DC component of voltage in energy storage inverter

Abstract

This invention discloses a detection circuit for the DC component of voltage in an energy storage inverter, comprising: 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 based on 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 based on the input phase voltage AC signal; the output terminal of the control unit is connected to the selection terminal of the voltage level selection unit and is used to output a selection signal to the voltage level selection unit; the voltage level selection unit is used to output either the first DC voltage or the second DC voltage to the control unit according to the selection signal. Different DC component detection units are set to meet the requirements for the accuracy of DC component voltage detection in different situations.

Description

Technical Field

[0001] This invention relates to the field of inverter technology, and more particularly to a detection circuit for the DC component of voltage in an energy storage inverter. Background Technology

[0002] With the development of photovoltaic energy storage technology and changes in market demand, more and more users are demanding residential energy storage inverters for power supply. Excess power generated during the day is stored in batteries for nighttime use or emergency power supply, while any further excess power is output to the grid in grid-connected mode. In off-grid mode, the energy storage inverter needs to operate with a load. During off-grid operation, errors in current sensor sampling, time delays in hardware circuitry, and the type of load (e.g., half-wave load) can cause deviations in the zero point of the inverter's AC output voltage, generating a DC component. A large DC component can lead to the risk of saturation of the downstream transformer core and potential damage to the load due to voltage imbalance. Therefore, residential energy storage inverters must meet certain DC component requirements during off-grid operation. The required DC component magnitude varies depending on the application; some requirements are relatively lenient, while others are stringent, requiring values ​​in the mV range. Therefore, a relatively accurate DC component detection circuit is needed to meet the adjustment needs of the entire software control system and ensure that the required DC component value remains within the specified range. Summary of the Invention

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

[0004] According to one aspect of the present invention, a detection circuit for the DC component of voltage of an energy storage inverter is provided. The energy storage inverter includes at least one phase voltage output terminal. The detection circuit for the DC component of 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 to generate a first DC voltage based on the input phase voltage AC signal.

[0006] The second DC component detection unit is connected to the phase voltage output terminal and is used to generate a second DC voltage based on the input 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 to output 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, for outputting 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 to 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 voltage acceptable to the second DC component detection unit is equal to 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.

[0010] Optionally, the first DC component detection unit includes: a high-impedance differential detection subunit, a first filtering subunit, an amplification subunit, and a first bias subunit;

[0011] The first input terminal of the high-impedance differential detection subunit is connected to the phase voltage output terminal, and the second input terminal of the high-impedance differential detection subunit is connected to the neutral line. The high-impedance differential detection subunit is used to generate a first detection signal based on the phase voltage AC signal.

[0012] The first end of the first filtering subunit is connected to the output end of the high-impedance differential detection subunit, and is used to filter out the AC signal in the first detection signal to generate the first filtered signal.

[0013] The input terminal of the amplification subunit is connected to the second terminal of the first filtering subunit, and is used to amplify the first filtered signal to generate a first amplified signal;

[0014] The input terminal of the first bias subunit is connected to the output terminal of the amplification 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.

[0015] Optionally, the high-impedance 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;

[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. 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, and 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, and the sixth resistor and the second capacitor are connected in parallel between the second input terminal 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, 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 within a first regulated range;

[0020] The first filter subunit 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 end of the high-impedance 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 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, and the second end of the eighth resistor is also connected to the input terminal of the amplification subunit.

[0023] The amplification subunit 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 terminal of the first filter subunit; the first terminal of the ninth resistor is connected to the second input terminal of the second operational amplifier; the second terminal of the ninth resistor is connected to the ground terminal; the first terminal of the tenth resistor is connected to the second input terminal of the second operational amplifier; the second terminal 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 bias subunit.

[0025] 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;

[0026] The first end of the eleventh resistor is connected to the output end of the amplification 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 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 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.

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

[0029] The input terminal of the first voltage follower subunit is connected to the second terminal of the first filter subunit, which is used to isolate the signal output by the output terminal of the voltage follower subunit from the first filter signal.

[0030] 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 amplification subunit, for filtering out AC signals in the signal output by the first voltage follower subunit.

[0031] Optionally, the first voltage follower subunit includes a fourth operational amplifier, the first input terminal of the fourth operational amplifier is connected to the second terminal of the first filter subunit, and the second input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier;

[0032] The second filter 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 terminal of the fourth operational amplifier, the second end of the fifteenth resistor is connected to the first end of the eighth capacitor, and the second end of the eighth capacitor is connected to ground. The first end of the sixteenth resistor is connected to the second end of the fifteenth resistor, and the second end of the sixteenth resistor is connected to the input terminal of the amplification 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 ground.

[0033] Optionally, the first DC component detection unit further includes a first filter clamping subunit, which is connected between the output terminal of the first bias subunit and the first input terminal of the voltage level selection unit, for filtering out AC signals in the first DC voltage and limiting the first DC voltage within a first voltage range.

[0034] Optionally, the first filter clamping subunit 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 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 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 subunit, a second-stage high-impedance detection subunit, a common-mode rejection subunit, a differential amplification subunit, and a second bias subunit;

[0038] The first input terminal of the first-stage high-impedance detection subunit is connected to the phase voltage output terminal, and the second input terminal of the first-stage high-impedance detection subunit is connected to the neutral line. The first-stage high-impedance 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.

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

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

[0041] The first input terminal of the differential amplifier subunit is connected to the first output terminal of the second-stage high-impedance detection subunit, and the second input terminal of the differential amplifier subunit is connected to the second output terminal of the second-stage high-impedance detection subunit. The differential amplifier subunit is used to generate a second amplified signal based on the second DC extracted signal.

[0042] The input terminal of the second bias subunit is connected to the output terminal 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.

[0043] Optionally, the first-stage high-impedance detection subunit 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, and 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, the second end of the third resistor string is connected to the first input terminal of the second-stage high-impedance detection subunit, the first end of the fourth resistor string is connected to the neutral line, and the second end of the fourth resistor string is connected to the second input terminal of the second-stage high-impedance detection subunit. 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 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 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 terminal of the first-stage high-impedance detection subunit. 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 ground. The second end of the eighteenth resistor also... The first end of the sixth resistor string is 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-impedance detection subunit, the second end of the sixth resistor string is connected to the first end of the twentieth resistor, the twentieth 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, and 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 terminal of the third diode is connected to the first output terminal of the second-stage high-impedance detection subunit, and the second terminal of the third diode is connected to a fourth voltage. The first terminal of the fourth diode is connected to a fifth voltage and the second terminal of the fourth diode is connected to the first output terminal of the second-stage high-impedance detection subunit. The first terminal of the fifth diode is connected to the second output terminal of the second-stage high-impedance detection subunit and the second terminal of the fifth diode is connected to the fourth voltage. The first terminal of the sixth diode is connected to the fifth voltage, and the second terminal of the sixth diode is connected to the second output terminal of the second-stage high-impedance detection subunit. The fourth voltage and the fifth voltage are opposite voltages to each other.

[0046] The differential amplifier subunit includes a 22nd resistor, a 23rd resistor, a 24th resistor, a 16th capacitor, a 5th operational amplifier, a 25th resistor, a 26th resistor, a 27th resistor, and a 17th capacitor;

[0047] The first end of the 22nd resistor is connected to the first output terminal of the second-stage high-impedance detection subunit, and the second end of the 22nd resistor is connected to the first input terminal of the fifth operational amplifier. The 23rd resistor, the 24th resistor, and the 16th capacitor are connected in parallel between the first input terminal of the fifth operational amplifier and the ground terminal. The first end of the 25th resistor is connected to the second output terminal of the second-stage high-impedance detection subunit, and the second end of the 25th resistor is connected to the second input terminal of the fifth operational amplifier. The 26th resistor is connected between the second input terminal of the fifth operational amplifier and the ground terminal. The 27th resistor and the 17th capacitor are connected in parallel between the second input terminal of the fifth operational amplifier and the output terminal 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 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 terminal of the twenty-eighth resistor is connected to the first power supply, the second terminal of the twenty-eighth resistor is connected to the first input terminal of the sixth operational amplifier, the first terminal of the eighteenth capacitor is connected to the first terminal of the twenty-eighth resistor, and the second terminal 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 amplifier 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, and the second output terminal of the second voltage follower subunit is connected to the second input terminal of the differential amplifier subunit. The second voltage follower subunit is used to isolate the signal input to the first input terminal of the differential amplifier subunit from the signal output from the first output terminal of the second-stage high-impedance detection subunit, and to isolate the signal input to the second input terminal of the differential amplifier subunit from 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 amplifier 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 amplifier subunit.

[0055] Optionally, the second DC component detection unit further includes: a twenty-ninth resistor and a nineteenth capacitor, wherein 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 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 bias subunit and the second input terminal of the voltage level selection unit, for filtering out AC signals in the second DC voltage and limiting 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 subunit, the second end of the thirtieth resistor is connected to the first end of the second thirtieth capacitor, the second end of the second thirtieth 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 terminal of the seventh diode is connected to the second input terminal of the voltage level selection unit, the second terminal of the seventh diode is connected to the first voltage, the first terminal of the eighth diode is connected to the ground terminal, and the second terminal of the eighth diode is connected to the second input terminal of the voltage level selection unit.

[0060] Optionally, a third filter clamping unit is also included, connected between the output terminal of the voltage level selection unit and the input terminal of the control unit, for filtering the voltage output by the voltage level selection unit and limiting the voltage input to the input terminal of the control unit within a first voltage.

[0061] Optionally, the third filter clamping unit includes: a thirty-first resistor, a twenty-first capacitor, a ninth diode, and a tenth 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 terminal.

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

[0064] The technical solution of this invention extracts the DC component of the voltage output from the energy storage inverter from the AC voltage using a first DC component detection unit and a second DC component detection unit. The two DC component detection units have different acceptable input voltage ranges. The control unit controls the voltage level selection circuit to output the voltage generated by the DC component detection unit that meets the requirements, based on the detection accuracy and control needs. When the DC component detection accuracy is 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 DC component detection accuracy is low, the control unit controls the voltage level selection unit to output the first DC voltage generated by the first DC component detection unit. By selecting different DC component detection units to generate different voltage outputs according to the different accuracy requirements of DC component detection, subsequent related control can be performed, meeting the accuracy requirements of DC component detection in various situations and improving the applicability and accuracy of the circuit.

[0065] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0066] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 A schematic diagram of a detection circuit for the DC component of voltage in an energy storage inverter, provided in an embodiment of the present invention;

[0068] Figure 2 A schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention;

[0069] Figure 3 A schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention;

[0070] Figure 4 A schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention;

[0071] Figure 5 A schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention;

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

[0073] Figure 7 A schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention. Detailed Implementation

[0074] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0075] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0076] Figure 1 This is a schematic diagram of a detection circuit for the DC component of an energy storage inverter voltage provided in an embodiment of the present invention. (Refer to...) Figure 1 The energy storage inverter includes at least one phase voltage output terminal. The detection circuit for 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. 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 based on the input 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 based on the input phase voltage AC signal.

[0079] The output terminal of the control unit 13 is connected to the selection terminal of the voltage level selection unit 12, and is used to output a selection 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, which is used to output one of the first DC voltage or the second DC voltage to the control unit 13 according to the selection signal.

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

[0082] An energy storage inverter can be a single-phase inverter, in which case it outputs only one phase voltage. It 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 designated as phase A, phase B, and phase C output terminals. The voltage between phase A and the neutral line is the phase A voltage, the voltage between phase B and the neutral line is the phase B voltage, and the voltage between phase C and the neutral line is the phase C output terminal. Each phase voltage output terminal corresponds one-to-one with a DC component detection module.

[0083] The phase voltage output terminal is used to output the phase voltage AC signal. The first DC component detection unit 10 extracts the DC component from the phase voltage AC signal output by the corresponding phase of the energy storage inverter and, after a series of operations, generates a first DC voltage recognizable by the control unit 13. The second DC component detection unit 11 extracts the DC component from the phase voltage AC signal output by the corresponding phase of the energy storage inverter and, after a series of operations, generates a second DC voltage recognizable by the control unit 13. The control unit 13 can be a microprocessor, such as a DSP (Digital Signal Processing), or a single-chip microcomputer or ARM processor, 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, a multiplexing chip with fewer channels, a selection switch, or similar devices or circuits.

[0084] The voltage range detectable by the first DC component detection unit 10 is greater than the voltage range detectable by the second DC component detection unit 11. For example, the first DC component detection unit 10 can detect a DC voltage component from -80V to 80V, the second DC component detection unit 11 can detect a DC voltage component from -1V to 1V, and the voltage range recognizable by the control unit 13 is 0-3V. When the voltage level selection unit 12 controls the voltage output of the first input terminal to the control unit 13, if the voltage received by 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 by 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 output of the second input terminal to the control unit 13, if the voltage received at the input terminal of the control unit 13 is 3V, the DC component of the voltage 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, the DC component of the voltage in the signal output by the energy storage inverter is -1V. Therefore, the second DC component detection unit 11 provides more precise detection and higher control accuracy.

[0085] Control unit 13 is used to control voltage level selection unit 12 to output either a first DC voltage or a second DC voltage to control unit 13 according to the magnitude of the DC component of the voltage output by the energy storage inverter and the control accuracy requirements. Control unit 13 is used to receive the voltage output from the output terminal OUT of voltage level selection unit 12 according to default settings, and then control voltage level selection unit 12 to output either the first DC voltage or the second DC voltage according to the magnitude of the voltage output from the output terminal OUT of voltage level selection unit 12 and the control accuracy requirements. The default setting can be that voltage level selection unit 12 outputs the first DC voltage. For example, after receiving the voltage output from the output terminal OUT of voltage level selection unit 12 according to default settings, if control unit 13 determines that the DC component of the voltage output by the energy storage inverter is less than a fourth voltage threshold and the user requires high control accuracy, then it controls voltage level selection unit 12 to output the second DC voltage to control unit 13, and control unit 13 performs subsequent closed-loop control based on the second DC voltage. If the control unit 13 receives the voltage output from the output terminal OUT of the voltage level selection unit 12 according to the default settings, and determines that the DC 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 based on the first DC voltage.

[0086] The control unit 13 processes the received first or second DC voltage and generates a PWM wave to perform closed-loop control on the DC component of the phase voltage AC signal output by the energy storage inverter. The pulse width and phase of the generated PWM wave differ depending on the voltage received by the control unit 13. For example, when the DC voltage component is greater than 1V, the control unit 13 performs closed-loop control based on the first DC voltage generated by the first DC component detection unit 10, which yields better results. When the DC voltage component is less than or equal to 1V, the first DC component detection unit 10 cannot adequately meet the accuracy and control requirements of the DC component. Therefore, the second DC component detection unit 11 is used to process the smaller DC component signal to meet the control requirements of the very small DC component. When higher accuracy is required, segmented accuracy calibration can be performed across the entire voltage detection range to meet specific needs.

[0087] The technical solution of this invention extracts the DC component of the voltage output from the energy storage inverter from the AC voltage using a first DC component detection unit and a second DC component detection unit. The two DC component detection units have different acceptable input voltage ranges. The control unit controls the voltage level selection circuit to output the voltage generated by the DC component detection unit that meets the requirements, based on the detection accuracy and control needs. When the DC component detection accuracy is 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 DC component detection accuracy is low, the control unit controls the voltage level selection unit to output the first DC voltage generated by the first DC component detection unit. By selecting different DC component detection units to generate different voltage outputs according to the different accuracy requirements of DC component detection, subsequent related control can be performed, meeting the accuracy requirements of DC component detection in various situations and improving the applicability and accuracy of the circuit.

[0088] Figure 2 This is a schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention, referred 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 bias subunit 104.

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

[0090] The first terminal of the first filtering subunit 102 is connected to the output terminal of the high-impedance differential detection subunit 101, and is used to filter out the AC signal in the first detection signal to generate the first filtered signal.

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

[0092] The input terminal of the first bias subunit 104 is connected to the output terminal of the amplification subunit 103, and is used to raise the zero-point voltage of the DC signal in the first amplified signal to generate the first DC voltage.

[0093] The high-impedance differential detection subunit 101 is used to perform high-impedance differential detection on the phase voltage AC signal to generate a first detection signal. The first filtering subunit 102 and other filtering subunits described below can be first-order or second-order filters. The first filtering subunit 102 can be an RC filter or an LC filter, or other software and circuits capable of filtering can be used; this embodiment does not specifically limit this. The first filtering subunit 102 filters out the AC component in the first detection signal, and the remaining DC component passes through and enters the amplification subunit 103. The amplification subunit 103 can be a proportional amplifier circuit. The amplification subunit 103 proportionally amplifies the extracted DC voltage component. After proportional amplification, the component enters the first bias subunit 104, which raises the DC voltage component from zero to the bias voltage. The magnitude of the bias voltage depends on the acceptable voltage range of the control unit 13. Optionally, the bias voltage is equal to half the sum of the upper and lower acceptable voltage limits of the control unit 13. The first bias subunit 104 is also used to adjust the voltage so that its output voltage is within the range allowed by the input voltage of the voltage level selection unit 12 and the control unit 13.

[0094] Figure 3 This is a schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention. Based on the above embodiment, referencing... Figure 1 and Figure 3 Optionally, the first DC component detection unit 10 further includes: a voltage follower subunit 105 and a second filter subunit 106;

[0095] The input terminal of the voltage follower subunit 105 is connected to the second terminal of the first filter subunit 102, which is used to isolate the signal output from the output terminal of the voltage follower subunit 105 from the first filter 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, 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 terminal of the first filtering subunit 102 through a voltage follower subunit 105 and a second filtering subunit 106. The voltage follower subunit 105 can be a voltage follower, and its output and input terminals are isolated to protect the preceding circuit from the influence of the following circuit. The second filtering subunit 106 is used to filter out the AC signal that was 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 only the DC component. The filtering cutoff frequency of the first filtering subunit 102 is higher than that of the second filtering subunit 106. That is, the first filtering subunit 102 filters out AC signals that are greater than or equal to a first frequency threshold, and the second filtering subunit 106 filters out AC signals that are greater than or equal to a second frequency threshold. 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 filter clamping subunit 107, which is connected between the output terminal of the first bias subunit and the first input terminal Y1 of the voltage level selection unit 12, for filtering out AC signals in the first DC voltage and limiting the first DC voltage within the first voltage range.

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

[0100] Figure 4 This is a schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention, referred 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 suppression subunit 113, a differential amplification subunit 114, and a second bias subunit 115.

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

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

[0103] The first end of the common-mode suppression subunit 113 is connected to the first output end of the second-stage high-impedance detection subunit, and the second end of the common-mode suppression subunit 113 is connected to the second output end of the second-stage high-impedance detection subunit. The common-mode suppression subunit 113 is used to filter out the common-mode signal in the second DC extracted signal.

[0104] The first input terminal of the differential amplifier subunit 114 is connected to the first output terminal of the second-stage high-impedance detection subunit 112, and the second input terminal of the differential amplifier subunit 114 is connected to the second output terminal of the second-stage high-impedance detection subunit 112. The differential amplifier subunit 114 is used to generate a second amplified signal based on the second DC extracted signal.

[0105] The input terminal of the second bias subunit 115 is connected to the output terminal of the differential amplifier subunit 114, and is used to raise 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 subunit 111 detects the AC voltage signal output by the energy storage inverter. The detected AC voltage signal is converted into a low-voltage signal approximating DC by the first-stage high-impedance detection subunit 111, and then enters the second-stage high-impedance detection subunit 112. The second-stage high-impedance detection subunit 112 constitutes the second-stage high-impedance detection, while simultaneously filtering out the AC signal from the first DC extraction signal, extracting the DC component, and clamping abnormal signals to a third voltage to protect the subsequent circuitry from damage due to overvoltage. The second DC extraction signal generated by the second-stage high-impedance detection subunit 112 is output and enters the common-mode suppression subunit 113. When a common-mode voltage exists in the detection circuit, it is discharged through the common-mode suppression subunit 113 to prevent excessive common-mode voltage from entering the subsequent circuitry and causing damage, thereby leading to abnormal detection accuracy or data anomalies. After the second DC extracted signal comes out from the common-mode suppression subunit 113, it enters the differential amplifier subunit 114 for differential signal proportional amplification processing. The processed signal is then boosted by the second bias subunit 115 to adjust to the range allowed by the input voltage of the voltage level selection unit 12 and the control unit 13.

[0107] Figure 5 This is a schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention, referred to... Figure 1 and Figure 5 Optionally, the second DC component detection unit 11 further includes: a second voltage follower subunit 116;

[0108] The first input terminal of the second voltage follower subunit 116 is connected to the first output terminal of the second-stage high-impedance detection subunit 112. The first output terminal of the second voltage follower subunit 116 is connected to the first input terminal of the differential amplifier subunit 114. The second input terminal of the second voltage follower subunit 116 is connected to the second output terminal of the second-stage high-impedance detection subunit 112. The second output terminal of the second voltage follower subunit 116 is connected to the second input terminal of the differential amplifier subunit 114. The second voltage follower subunit 116 is used to isolate the signal input to the first input terminal of the differential amplifier subunit 114 from the signal output from the first output terminal of the second-stage high-impedance detection subunit 112, and to isolate the signal input to the second input terminal of the differential amplifier subunit 114 from the signal output from the second output terminal of the second-stage high-impedance detection subunit 112.

[0109] Continue to refer to Figure 1 and Figure 5Optionally, 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 bias subunit 115, and is used to filter the second amplified signal output by the differential amplification subunit 114 to further filter out AC signals. The second filtering clamping subunit 118 is connected between the output terminal of the second bias subunit 115 and the second input terminal Y2 of the voltage level selection unit 12, and is used to filter out AC signals 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 AC signals in the signal output by the second bias subunit 115, and on the other hand, clamps the abnormal signal of the second input terminal Y2 of the input voltage level selection unit 12 to the first voltage to prevent the voltage level selection unit 12 from being damaged by excessive voltage.

[0110] Figure 6 This is a schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention, referred to... Figure 1 and Figure 6 Optionally, the detection circuit for the DC component of the energy storage inverter voltage also includes a third filter clamping unit 14. The third filter clamping unit 14 is connected between the output terminal OUT of the voltage level selection unit 12 and the input terminal of the control unit 13. It filters the voltage output by the voltage level selection unit 12 and limits the voltage at the input terminal of the control unit 13 to within a first voltage range. The third filter clamping unit 14 filters the signal in the input control unit 13 and simultaneously controls the voltage in the input control unit 13 to be less than or equal to the first voltage, preventing excessively high DC voltage components from entering the control unit 13 and causing damage. Figure 6 In the first DC component detection unit 10, there are: 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 bias subunit 104, and a first filter clamping subunit 107. The second DC component detection subunit 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 bias subunit 115, and a second filter clamping subunit 118.

[0111] Figure 7 This is a schematic diagram of another detection circuit for the DC component of the voltage of an energy storage inverter provided in an embodiment of the present invention. Figure 7 for Figure 6 A specific circuit diagram, see reference. Figure 6 and Figure 7Optionally, 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, and 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 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 a first regulated range.

[0116] The first resistor string includes resistors R32 (32nd), R33 (33rd), R34 (34th), R35 (35th), R36 (36th), and R37 (37th) connected in series. The second resistor string includes resistors R38 (38th), R39 (39th), R40 (40th), R41 (41st), R42 (42nd), and R43 (43rd) connected in series. 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, constitute one high-impedance detection path to prevent excessively high potential input to the first input terminal of the first operational amplifier U1, which could damage the first operational amplifier U1. The second resistor string, the fourth resistor R4, and the fifth resistor R5 constitute another high-impedance detection path to prevent excessively high potential input to the second input terminal of the first operational amplifier U1, which could also damage the first operational amplifier U1. In this embodiment and the embodiments described below, the first input terminal of each operational amplifier can be the positive terminal, and the second input terminal can be the negative terminal; this will not be elaborated further. The output signal U1i of the first operational amplifier U1 is given by: U1i = R6i * U1i / (R2i + R4i), where R6i is the resistance of the sixth resistor R6, U1i is the DC component voltage between the phase voltage output terminal R and the neutral line N, R2i is the resistance of the second resistor string, and R4i is the resistance 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, and the output terminal of the first transient suppression diode T1 is connected to the second end of the first resistor string. The output terminal of the second transient suppression diode T2 is connected to the second end 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 to a first regulated voltage range. Optionally, the first regulated voltage range is -12V to 12V, ensuring that abnormal voltages input to the first and second input terminals of the first operational amplifier U1 do not exceed the voltage that the input ports of the first operational amplifier U1 can withstand.

[0117] The first filter subunit includes: the seventh resistor R7, the third capacitor C3, the eighth resistor R8, and the fourth capacitor C4;

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

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

[0120] Specifically, the seventh resistor R7, the third capacitor C3, the eighth resistor R8, and the fourth capacitor C4 constitute 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 subunit 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 subunit 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 constitutes a voltage follower, realizing buffering and isolation between the signal input to the fourth operational amplifier U4 and the signal output from the fourth operational amplifier U4.

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

[0123] The amplification subunit 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 subunit 103 and is connected to the second terminal of the first filtering subunit 102. When the first DC detection unit 10 also includes a first voltage follower subunit 105 and a second filtering subunit 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, and the second terminal of the ninth resistor R9 is connected to ground (GND). The first terminal of the tenth resistor R10 is connected to the second input terminal of the second operational amplifier U2, and 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 subunit 104. The signal output from the second filtering subunit 106 enters a non-inverting proportional amplifier circuit, which proportionally amplifies the extracted DC voltage component. This proportional amplifier circuit is composed of the second operational amplifier U2, the ninth resistor R9, and the tenth resistor R10. In this circuit, 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 subunit 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 of the amplifier subunit 103, specifically to the output of the second operational amplifier U2. The second end of the eleventh resistor R11 is connected to the second input of the third operational amplifier U3. The twelfth resistor R12 and the fifth capacitor C5 are connected in parallel between the second input of the third operational amplifier U3 and the output of the third operational amplifier U3.

[0126] The first terminal of the sixth capacitor C6 is connected to the first power supply V1, and the second terminal of the sixth capacitor C6 is connected to the ground terminal GND. The first terminal of the thirteenth resistor R13 is connected to the first power supply VI, and the second terminal of the thirteenth resistor R13 is connected to the first input terminal of the third operational amplifier U3. The fourteenth resistor R14 and the seventh capacitor C7 are connected in parallel between the first input terminal 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 generating circuit to generate a bias voltage. In this embodiment, as an example, the first power supply V1 provides a 3V DC voltage, and the minimum allowable voltage at the input port of the control unit 13 is 0V, while the maximum allowable voltage is 3V. Therefore, the bias voltage is equal to 1.5V, meaning that 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 input to the first input terminal of the third operational amplifier U3. The output of the third operational amplifier U3 is equal to 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 from the amplification subunit 103 enters the first bias subunit 104, which boosts the DC component of the voltage by 1.5V. This is then used in conjunction with the proportional amplifier circuit for proportional amplification adjustment, adjusting the voltage to within the allowable voltage range of the input terminals of the voltage level selection unit 12 and the control unit 13. The 1.5V bias and proportional amplifier circuit consists 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. The signal is then output to the subsequent circuits through the 1.5V bias and proportional amplifier circuit.

[0128] The first filter clamping subunit 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 of the first bias subunit 104, specifically to the output of the third operational amplifier U3. The second end of the seventeenth resistor R17 is connected to the first input 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 terminal of the first diode D1 is connected to the second terminal of the seventeenth resistor R17, and the second terminal of the first diode D1 is connected to the first voltage V2. The first terminal of the second diode D2 is connected to the ground terminal GND, and the second terminal of the second diode D2 is connected to the second terminal of the seventeenth resistor R17.

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

[0132] The first-stage high-impedance detection subunit 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, and 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, and the second end of the third resistor string is connected to the first input terminal of the second-stage high-impedance detection subunit 112. The first end of the fourth resistor string is connected to the neutral line N, and the second end of the fourth resistor string is connected to the second input terminal of the second-stage high-impedance detection subunit 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 subunit 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 terminal of the first-stage high-impedance detection subunit 111, and 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 terminal of the differential amplifier subunit 114. When the second DC component detection unit includes a second voltage follower subunit 116, the second end of the eighteenth resistor R18 is connected to the differential amplifier subunit 114 through the second voltage follower subunit 116. The first input terminal of the differential amplifier subunit 114 is connected, the first terminal of the sixth resistor string is connected to the second output terminal of the first-stage high-impedance detection subunit 111, the second terminal of the sixth resistor string is connected to the first terminal of the twentieth resistor R20, the twenty-first resistor R21 and the thirteenth capacitor C13 are connected in parallel between the second terminal of the twentieth resistor R20 and the ground terminal GND, and the second terminal of the twentieth resistor R20 is also connected to the second input terminal of the differential amplifier subunit 114. When the second DC component detection unit includes a second voltage follower subunit, the second terminal of the twentieth resistor R20 is connected to the second input terminal of the differential amplifier subunit 114 through the second voltage follower subunit 116, the fourteenth capacitor C14 is connected in parallel between the second terminal of the fifth resistor string and the second terminal of the sixth resistor string, the fifteenth capacitor C15 and the third clamping device are connected in parallel between the second terminal of the eighteenth resistor R18 and the second terminal of the twentieth resistor R20, and the third clamping device is used to limit the voltage of the second DC extraction signal to within the third voltage.

[0134] Specifically, the third resistor string includes resistors R44, R45, and R46 connected in series, and the fourth resistor string includes resistors R47, R48, and R49 connected in series. The first clamping device includes a third transient suppression diode T3 and a fourth transient suppression diode T4. The input terminal of the third transient suppression diode T3 is connected to the input terminal of the fourth transient suppression diode T4, and the output terminal of the third transient suppression diode T3 is connected to the second terminal of the third resistor string, i.e., the second terminal of resistor R46. The output terminal of the fourth transient suppression diode T4 is connected to the second terminal of the fourth resistor string, i.e., the second terminal of resistor R49. The second clamping device is used to control the voltage difference between the second terminals of the third and fourth resistor strings to be less than or equal to a second voltage. The third and fourth resistor strings form a first-stage high-impedance detection to detect the AC voltage signal output by the energy storage inverter. The detected signal enters the first-stage clamping protection and filtering circuit composed of the eleventh capacitor C11 and the second clamping device, which converts the detected AC voltage signal into a low-voltage signal that is close to DC, and then enters the second-stage high-impedance detection subunit 112.

[0135] The fourth resistor string includes the 50th resistor R50, the 51st resistor R51, and the 52nd resistor R52 connected in series. The fifth resistor string includes the 53rd resistor R53, the 54th resistor R54, and the 55th resistor R55 connected in series. The third clamping device includes a fifth transient suppression diode T5 and a sixth transient suppression diode T6. The input terminal of the fifth transient suppression diode T5 is connected to the input terminal of the sixth transient suppression diode T6. The output terminal of the fifth transient suppression diode T5 is connected to the second terminal of the 18th resistor R18. The output terminal of the sixth transient suppression diode T6 is connected to the second terminal of the 20th resistor R20. The third clamping device is used to control the voltage difference between the second terminal of the 20th resistor R20 and the second terminal of the 18th resistor R18 to be less than or equal to the third voltage. The fifth and sixth resistor strings constitute a two-stage high-impedance detection system. The nineteenth resistor R19, the twelfth capacitor C12, the twenty-first resistor R21, and the thirteenth capacitor C13, along 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, generate a voltage divider signal. This signal extracts the DC component from the AC voltage signal. The fifth transient suppression diode T5 and the sixth transient suppression diode T6 clamp the abnormal signal to a third voltage, protecting the subsequent circuitry from damage due to overvoltage. Optionally, the second voltage is 12V, and the third voltage is 3.3V. The cutoff frequency of the first-stage high-impedance detection subunit 111 is higher than the cutoff frequency of the second-stage high-impedance detection subunit 112 to ensure the useful DC component signal passes through intact, while effectively filtering and clamping high-frequency interference signals to prevent excessive voltage from damaging subsequent circuitry.

[0136] The common-mode suppression subunit 113 includes a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6. The first terminal of the third diode D3 is connected to the first output terminal of the second-stage high-impedance detection subunit 112, and the second terminal of the third diode D3 is connected to a fourth voltage V3. The first terminal of the fourth diode D4 is connected to a fifth voltage V4, and the second terminal of the fourth diode D4 is connected to the first output terminal of the second-stage high-impedance detection subunit 112. The first terminal of the fifth diode D5 is connected to the second output terminal of the second-stage high-impedance detection subunit 112, and the second terminal of the fifth diode D5 is connected to the fourth voltage V3. The first terminal of the sixth diode D6 is connected to the fifth voltage V4, and the second terminal of the sixth diode D6 is connected to the second output terminal of the second-stage high-impedance detection subunit 112. The fourth voltage V3 and the fifth voltage V4 are opposite voltages to each other.

[0137] Optionally, the fourth voltage V3 is +5V and the fifth voltage V4 is -5V. Because the DC signal detected by the second DC component detection unit is relatively weak, even small interferences can significantly affect the detected DC component of the voltage. Therefore, a common-mode rejection subunit 113 is needed to filter out common-mode signal interference. When a common-mode voltage is present, it is conducted to the ground terminal GND through the common-mode rejection subunit to prevent excessive common-mode voltage from entering the subsequent second voltage follower subunit 116, causing the subsequent operational amplifier circuit to lose linearity or be damaged, thus leading to abnormal detection accuracy or data anomalies.

[0138] The second voltage follower subunit 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 subunit 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 amplifier subunit 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 subunit 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, and the output terminal of the eighth operational amplifier U8 is connected to the second input terminal of the differential amplifier subunit 114.

[0141] The differential amplifier subunit 114 includes a 22nd resistor R22, a 23rd resistor R23, a 24th resistor R24, a 16th capacitor C16, a 5th operational amplifier U5, a 25th resistor R25, a 26th resistor R26, a 27th resistor R27, and a 17th capacitor C17.

[0142] The first end of the twenty-second resistor R22 is connected to the first output terminal of the second-stage high-impedance detection subunit 112, and can be connected to the eighteenth resistor R18 through the second voltage follower subunit 116. The second end 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 end of the twenty-fifth resistor R25 is connected to the second output terminal of the second-stage high-impedance detection subunit 112, and the second end 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 and the output terminal of the fifth operational amplifier U5.

[0143] Specifically, the differential amplifier subunit 114 is used for 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 terminal of the differential amplifier subunit 114, the second end of the twenty-ninth resistor R29 is connected to the input terminal of the second bias subunit 115, the first end of the nineteenth capacitor C19 is connected to the second end of the twenty-ninth resistor R29, and 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. The filtered signal enters the second bias subunit 115.

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

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

[0148] The second bias subunit 115 is used to generate a bias voltage. The difference between its output and input terminals is equal to the bias voltage. In this embodiment, the bias voltage is set to 1.5V. The filtered signal is then passed through a 1.5V bias circuit to raise the DC component voltage by 1.5V, which meets the voltage input range and accuracy requirements of the control unit 13.

[0149] The second filter clamping subunit 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 of the second bias subunit 115, specifically to the output of the sixth operational amplifier U6. The second end of the thirtieth resistor R30 is connected to the first end of the thirtieth capacitor C20. The second end of the thirtieth 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 terminal of the seventh diode D7 is connected to the second input terminal Y2 of the voltage level selection unit 12, and the second terminal of the seventh diode D7 is connected to the first voltage V2. The first terminal of the eighth diode D8 is connected to the ground terminal GND, and the second terminal 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 to filter the signal output from the second bias subunit 115. The seventh diode D7 and the eighth diode D8 form a clamping circuit to limit the voltage input to the second input terminal Y2 of the voltage level selection unit 12 within a first voltage range. The signal output from the second bias subunit 115 enters the second filter clamping subunit 118 to prevent the DC component of the voltage signal from being too large, which could cause excessive input current to the downstream voltage level selection unit 12, and to clamp the excessively high input DC component of the 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, and the second end of the twenty-first capacitor C21 is connected to the ground terminal GND.

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

[0156] The 31st resistor R31 and the 21st capacitor C21 form a first-order low-pass filter circuit, which is used to filter the signal output by the voltage level selection unit 12. The 9th diode D9 and the 10th diode D10 form a clamping circuit, which is used to control the voltage in the input control unit 13 to be less than or equal to the first voltage.

[0157] The voltage level selection unit 12 includes a first sub-selection terminal A and a second sub-selection terminal B. In one optional embodiment, when the control unit 13 sends a first selection signal to the selection terminal, it controls the voltage level selection unit 12 to output a first DC voltage to the control unit 13; when it sends a second selection signal to the selection terminal, it controls the voltage level selection unit 12 to output a second DC voltage to the control unit 13. The first selection signal can be 10, that is, the potential received by the first sub-selection terminal A is "1" and the potential received by the second sub-selection terminal B is "0". The second selection signal can be 01, that is, the potential received by the first sub-selection terminal A is "0" and the potential received by the second sub-selection terminal B is "1".

[0158] use Figure 7 The circuit shown was used in multiple experiments to obtain the test data of the detection circuit for the DC component of the energy storage inverter voltage, as shown in Table 1.

[0159] Table 1 Test data of the detection circuit for 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 and control effect is very good. When the DC component is less than or equal to 1V, the first DC component detection unit cannot meet the accuracy and control requirements of the DC component. Therefore, the second DC component detection unit is needed to process the smaller DC component signal to meet the control requirements of the very small DC component.

[0163] In this embodiment, the first DC component detection unit uses a sampling-then-filtering method to detect the DC component in the signal output by the energy storage inverter, and the second DC component detection unit uses a filtering-then-sampling method to detect the DC component in the signal output by the energy storage inverter. Furthermore, the two-stage high-impedance detection method can reduce detection deviation and is more suitable for detecting weak DC component signals.

[0164] In this embodiment, the devices used to implement the clamping function can be transient voltage suppressor diodes (TVS diodes), Zener diodes, or other voltage clamping devices or circuits with the same function. Both the first bias subunit 104 and the second bias subunit 115 can use a 1.5V bias or can be adjusted to other bias voltage circuits with the help of a proportional circuit, such as adjusting the bias voltage to 1V.

[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 described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0166] The specific embodiments described above do not constitute a limitation on the scope of protection of this 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 principles of this invention should be included within the scope of protection of this invention.

Claims

1. A detection circuit for the DC component of voltage in an energy storage inverter, characterized in that, 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, 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 based on 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 based on the input phase voltage AC signal; The output terminal of the control unit is connected to the gating terminal of the voltage level selection unit, and is used to output a gating signal to the voltage level selection unit; 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, for outputting one of the first DC voltage or the second DC voltage to the control unit according to the gating signal; Wherein, the voltage acceptable to 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 voltage acceptable to the second DC component detection unit is equal to 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; The first DC component detection unit includes: a high-impedance differential detection subunit, a first filtering subunit, an amplification subunit, and a first bias subunit; The first input terminal of the high-impedance differential detection subunit is connected to the phase voltage output terminal, and the second input terminal of the high-impedance differential detection subunit is connected to the neutral line. The high-impedance differential detection subunit is used to generate a first detection signal based on the phase voltage AC signal. The first end of the first filtering subunit is connected to the output end of the high-impedance differential detection subunit, and is used to filter out the AC signal in the first detection signal to generate the first filtered signal. The input terminal of the amplification subunit is connected to the second terminal of the first filtering subunit, and is used to amplify the first filtered signal to generate a first amplified signal; The input terminal of the first bias subunit is connected to the output terminal of the amplification 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. The high-impedance 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. 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. 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. 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, and the second end of the fourth resistor is connected to the second input terminal of the first operational amplifier. 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, and the sixth resistor and the second capacitor are connected in parallel between the second input terminal and the output terminal 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 within a first regulated range; The first filter 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-impedance 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 terminal. 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, and the second end of the eighth resistor is also connected to the input terminal of the amplification subunit. The amplification subunit includes: 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 filter subunit, i.e., the second terminal of the eighth resistor. The first terminal of the ninth resistor is connected to the second input terminal of the second operational amplifier, and the second terminal of the ninth resistor is connected to the ground terminal. The first terminal of the tenth resistor is connected to the second input terminal of the second operational amplifier, and the second terminal 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 bias 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 amplification 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 and the output end of the third operational amplifier. The first terminal of the sixth capacitor is connected to the first power supply, the second terminal of the sixth capacitor is connected to the ground terminal, the first terminal of the thirteenth resistor is connected to the first power supply, the second terminal 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. The first input terminal of each operational amplifier is the positive terminal, and the second input terminal is the negative terminal.

2. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 1, characterized in that, The first DC component detection unit further includes: a first voltage follower subunit and a second filter subunit; The input terminal of the first voltage follower subunit is connected to the second terminal of the first filter subunit, which is used to isolate the signal output by the output terminal of the voltage follower subunit from the first filter 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 amplification subunit, for filtering out AC signals in the signal output by the first voltage follower subunit.

3. The detection circuit for the DC component of the energy storage inverter voltage according to claim 2, characterized in that, The first voltage follower subunit includes a fourth operational amplifier. The first input terminal of the fourth operational amplifier is connected to the second terminal of the first filter subunit, i.e., the second terminal of the eighth resistor. The second input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier. The first input terminal of the fourth operational amplifier is a positive terminal and the second input terminal is a negative terminal. The second filter 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 terminal of the fourth operational amplifier. The second end of the fifteenth resistor is connected to the first end of the eighth capacitor, and the second end of the eighth capacitor is connected to ground. The first end of the sixteenth resistor is connected to the second end of the fifteenth resistor, and the second end of the sixteenth resistor is connected to the input terminal of the amplification subunit, i.e., the first input terminal of the second operational amplifier. 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 ground.

4. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 1, characterized in that, The first DC component detection unit further includes a first filter clamping subunit, which is connected between the output terminal of the first bias subunit and the first input terminal of the voltage level selection unit, for filtering out AC signals in the first DC voltage and limiting the first DC voltage within a first voltage range.

5. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 4, 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 terminal. The first terminal of the first diode is connected to the second terminal of the seventeenth resistor, the second terminal of the first diode is connected to a first voltage, the first terminal of the second diode is connected to the ground terminal, and the second terminal of the second diode is connected to the second terminal of the seventeenth resistor. The first diode has a positive terminal at its first end and a negative terminal at its second end, and the second diode has a positive terminal at its first end and a negative terminal at its second end.

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

7. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 6, characterized in that, The first-stage high-impedance detection subunit 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, and 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, and the second end of the third resistor string is connected to the first input terminal of the second-stage high-impedance detection subunit. The first end of the fourth resistor string is connected to the neutral line, and the second end of the fourth resistor string is connected to the second input terminal of the second-stage high-impedance detection subunit. 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. The second-stage high-impedance 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 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 terminal of the first-stage high-impedance detection subunit. 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 ground. The second end of the eighteenth resistor also... The first end of the sixth resistor string is 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-impedance detection subunit, the second end of the sixth resistor string is connected to the first end of the twentieth resistor, the twentieth 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, and 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 includes a third diode, a fourth diode, a fifth diode, and a sixth diode. The first terminal of the third diode is connected to the first output terminal of the second-stage high-impedance detection subunit, and the second terminal of the third diode is connected to a fourth voltage. The first terminal of the fourth diode is connected to a fifth voltage and the second terminal of the fourth diode is connected to the first output terminal of the second-stage high-impedance detection subunit. The first terminal of the fifth diode is connected to the second output terminal of the second-stage high-impedance detection subunit and the second terminal of the fifth diode is connected to the fourth voltage. The first terminal of the sixth diode is connected to the fifth voltage, and the second terminal of the sixth diode is connected to the second output terminal of the second-stage high-impedance detection subunit. The fourth voltage and the fifth voltage are opposite voltages. The first terminal of each diode is positive, and the second terminal is negative. The differential amplifier subunit includes a 22nd resistor, a 23rd resistor, a 24th resistor, a 16th capacitor, a 5th operational amplifier, a 25th resistor, a 26th resistor, a 27th resistor, and a 17th capacitor; The first end of the 22nd resistor is connected to the first output terminal of the second-stage high-impedance detection subunit, i.e., the second end of the 18th resistor. The second end of the 22nd resistor is connected to the first input terminal of the fifth operational amplifier. The 23rd resistor, the 24th resistor, and the 16th capacitor are connected in parallel between the first input terminal of the fifth operational amplifier and the ground terminal. The first end of the 25th resistor is connected to the second output terminal of the second-stage high-impedance detection subunit, i.e., the second end of the 20th resistor. The second end of the 25th resistor is connected to the second input terminal of the fifth operational amplifier. The 26th resistor is connected between the second input terminal of the fifth operational amplifier and the ground terminal. The 27th resistor and the 17th capacitor are connected in parallel between the second input terminal of the fifth operational amplifier and the output terminal of the fifth operational amplifier. The first input terminal of the fifth operational amplifier is the positive input terminal, and the second input terminal is the negative input terminal. 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 terminal of the twenty-eighth resistor is connected to the first power supply, the second terminal of the twenty-eighth resistor is connected to the first input terminal of the sixth operational amplifier, the first terminal of the eighteenth capacitor is connected to the first terminal of the twenty-eighth resistor, and the second terminal of the eighteenth capacitor is connected to the ground terminal. The first input terminal of the sixth operational amplifier is the positive terminal, and the second input terminal is the negative terminal.

8. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 7, 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-impedance detection subunit, i.e., the second terminal of the eighteenth resistor. The first output terminal of the second voltage follower subunit is connected to the first input terminal of the differential amplifier subunit, i.e., the first terminal of the twenty-twelfth resistor. 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 amplifier subunit. The second voltage follower subunit is used to isolate the signal input to the first input terminal of the differential amplifier subunit from the signal output from the first output terminal of the second-stage high-impedance detection subunit, and to isolate the signal input to the second input terminal of the differential amplifier subunit from the signal output from the second output terminal of the second-stage high-impedance detection subunit.

9. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 8, 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 second terminal of the first output terminal of the second-stage high-impedance detection subunit, which is the second terminal of the eighteenth resistor. The second input terminal of the seventh operational amplifier is connected to the output terminal of the seventh operational amplifier. 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 seventh operational amplifier is the positive terminal, and the second input terminal is the negative terminal. The first input terminal of the eighth operational amplifier is connected to the second output terminal of the second-stage high-impedance detection subunit, i.e., the second terminal of the twentieth resistor. The second input terminal of the eighth operational amplifier is connected to the output terminal of the eighth operational amplifier. The output terminal of the eighth operational amplifier is connected to the second input terminal of the differential amplifier subunit, i.e., the first terminal of the twenty-fifth resistor. The first input terminal of the eighth operational amplifier is the positive terminal, and the second input terminal is the negative terminal.

10. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 6, characterized in that, 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 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 terminal.

11. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 6, characterized in that, The second DC component detection unit further includes a second filter clamping subunit, which is connected between the output terminal of the second bias subunit and the second input terminal of the voltage level selection unit, for filtering out AC signals in the second DC voltage and limiting the second DC voltage within the first voltage.

12. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 11, characterized in that, The second filter clamping subunit includes: a thirtieth resistor, a twentieth capacitor, a seventh diode, and an eighth diode; The first end of the thirtieth resistor is connected to the output end of the second bias subunit, the second end of the thirtieth resistor is connected to the first end of the second thirtieth capacitor, the second end of the second thirtieth 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. The first end of the seventh diode is connected to the second input terminal of the voltage level selection unit, and 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 terminal, and the second end of the eighth diode is connected to the second input terminal of the voltage level selection unit. The first end of the seventh diode is the positive terminal and the second end is the negative terminal, and the first ends of the eighth diode are all positive terminals and the second ends are all negative terminals.

13. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 1, characterized in that, It also includes a third filter clamping unit, connected between the output terminal of the voltage level selection unit and the input terminal of the control unit, for filtering the voltage output by the voltage level selection unit and limiting the voltage input to the input terminal of the control unit within a first voltage.

14. The detection circuit for the DC component of the voltage of the energy storage inverter according to claim 13, characterized in that, The third filter clamping unit includes: a thirty-first resistor, a twenty-first capacitor, a ninth diode, and a tenth diode; 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 terminal. The first end of the ninth diode is connected to the input terminal 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 terminal, the second end of the tenth diode is connected to the input terminal of the control unit, the first end of the ninth diode is the positive terminal and the second end is the negative terminal, and the first ends of the tenth diode are all positive terminals and the second ends are all negative terminals.

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