Inverter control method, device and system and storage medium

Abstract

The invention provides an inverter control method, device and system and a storage medium, and the method comprises the steps: detecting the DC component of each phase of current outputted by an inverter, and determining the average value of the DC components of multi-phase current; determining an initial reference value corresponding to the bus voltage deviation according to the DC component average value and a preset reference value; determining a target reference value corresponding to the bus voltage deviation according to the output power of the inverter and the initial reference value; controlling an inverter according to the bus voltage difference between the positive bus and the negative bus and a target reference value so as to suppress the influence of the bus voltage deviation on the direct current component of each phase of current; wherein the absolute value of the target reference value is equal to the absolute value of the initial reference value, and the positive and negative of the target reference value are consistent with the positive and negative of the output power of the inverter. The inverter can be accurately controlled according to the bus voltage difference and the target reference value, and the influence of the bus voltage deviation on the direct-current component of each phase of current when the inverter is in the unbalanced mode can be suppressed.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and in particular to an inverter control method, device, system and storage medium. Background Art

[0002] At present, photovoltaic power generation systems can use solar cell modules to convert solar radiation energy into electrical energy, and use inverters to convert direct current into sinusoidal alternating current with the same frequency and phase as the grid voltage, and finally connect to the grid to reduce the load of the grid. However, existing photovoltaic grid-connected inverters cannot automatically suppress DC injection, which will include a DC component in the AC output of the inverter, causing grid voltage fluctuations and affecting the stability of the power system and the safe operation of equipment. Summary of the invention

[0003] The present application provides an inverter control method, device, system and storage medium, aiming to solve the above technical problems.

[0004] In a first aspect, the present application provides an inverter control method, wherein the inverter is used to output a multi-phase AC voltage according to a DC voltage input by a positive bus and a negative bus, and the method includes:

[0005] Detecting the DC component of each phase current output by the inverter and determining the average value of the DC component of the multi-phase current;

[0006] Determine an initial reference value corresponding to the bus voltage deviation according to the average value of the DC component and the preset reference value;

[0007] Determine the target reference value corresponding to the bus voltage deviation according to the output power of the inverter and the initial reference value;

[0008] controlling the inverter according to the bus voltage difference between the positive bus and the negative bus and a target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current;

[0009] The absolute value of the target reference value is equal to the initial reference value, and the positive and negative values ​​of the target reference value are consistent with the positive and negative values ​​of the inverter output power.

[0010] In some embodiments, the step of controlling the inverter according to the bus voltage difference between the positive bus and the negative bus and the target reference value includes:

[0011] Determine a first output result according to the bus voltage difference and the target reference value;

[0012] adding the first output result to the control loop output result of the inverter to determine a total output result;

[0013] The duty cycle of the control signal is determined according to the total output result and the bus voltage, the bus voltage includes at least one of a positive bus voltage and a negative bus voltage, and the control signal is used to control the switch in the inverter.

[0014] In some embodiments, the step of determining the duty cycle of the control signal according to the total output result and the bus voltage includes:

[0015] When the total output result is greater than zero, the duty cycle of the control signal is determined according to the total output result and the positive bus voltage, and the duty cycle of the control signal is negatively correlated with the absolute value of the positive bus voltage;

[0016] When the total output result is less than zero, the duty cycle of the control signal is determined according to the total output result and the negative bus voltage, and the duty cycle of the control signal is negatively correlated with the absolute value of the negative bus voltage.

[0017] In some embodiments, the method further comprises:

[0018] Determine a second output result of each phase current according to the DC component of each phase current and the average value of the DC component;

[0019] The second output result of each phase current is added to the control loop output result of the inverter to determine the total output result.

[0020] In some embodiments, the step of detecting the DC component of each phase current output by the inverter includes:

[0021] determining a measurement error of a detection circuit for reading a DC measurement result of each phase current output by the inverter;

[0022] The DC component of each phase current output by the inverter is determined according to the measurement error of the detection circuit and the DC measurement result of each phase current.

[0023] In some embodiments, the step of determining a measurement error of the detection circuit includes:

[0024] When the inverter is not working and the AC side of the inverter is connected to the grid, measure the current measurement results of the AC side of the inverter multiple times;

[0025] The measurement error of the detection circuit is determined based on multiple current measurement results on the AC side of the inverter.

[0026] In some embodiments, the step of determining an initial reference value corresponding to the bus voltage deviation according to an average value of the DC component and a preset reference value includes:

[0027] The DC component average value and the preset reference value are input into the first proportional-integral controller, so that the first proportional-integral controller outputs an initial reference value.

[0028] In a second aspect, the present application provides an inverter control device, the inverter is used to output a multi-phase AC voltage according to a DC voltage input by a positive bus and a negative bus, and the device includes:

[0029] A DC component detection module, which is used to detect the DC component of each phase current output by the inverter and determine the average DC component of the multi-phase current;

[0030] An initial reference determination module, the initial reference determination module is used to determine an initial reference value corresponding to the bus voltage deviation according to an average value of a DC component and a preset reference value;

[0031] A target reference determination module, which is used to determine a target reference value corresponding to a bus voltage deviation according to an output power of the inverter and an initial reference value;

[0032] A DC component control module, the DC component control module is used to control the inverter according to the bus voltage difference between the positive bus and the negative bus and the target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current;

[0033] The absolute value of the target reference value is equal to the initial reference value, and the positive and negative values ​​of the target reference value are consistent with the positive and negative values ​​of the inverter output power.

[0034] In a third aspect, the present application provides an inverter control system, comprising a memory and a processor, wherein the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the steps in the inverter control method described in the first aspect.

[0035] In a fourth aspect, the present application provides a storage medium storing a plurality of instructions, wherein the instructions are suitable for loading by a processor to execute the steps in the inverter control method as described in the first aspect.

[0036] The present application detects the DC component of each phase current output by the inverter and determines the average DC component of the multi-phase current, so that the initial reference value corresponding to the bus voltage deviation can be determined based on the DC component average value and a preset reference value. After determining the initial reference value, the target reference value corresponding to the bus voltage deviation can be determined in combination with the output power of the inverter and the initial reference value. Finally, the inverter is controlled based on the bus voltage difference between the positive bus and the negative bus and the target reference value, so that the inverter operates in an unbalanced mode to suppress the influence of the bus voltage deviation on the DC component of each phase current.

[0037] Since the absolute values ​​of the target reference value and the initial reference value are equal, and the positive and negative values ​​of the target reference value are consistent with the positive and negative values ​​of the inverter output power, for example, when the inverter output power is positive, the initial reference value is assigned a positive value to obtain the target reference value; conversely, when the inverter output power is negative, the initial reference value is assigned a negative value to obtain the target reference value. Ultimately, the inverter can be accurately controlled according to the bus voltage difference and the target reference value to avoid positive and negative changes in the inverter output power, resulting in the inability to accurately suppress the influence of the bus voltage deviation on the DC component of each phase current. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the 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 work.

[0039] Figure 1 A schematic diagram of an inverter circuit in an embodiment of the present application is shown;

[0040] Figure 2 A schematic diagram of a flow chart of an inverter control method in an embodiment of the present application is shown;

[0041] Figure 3 A schematic diagram of a process of controlling an inverter in an embodiment of the present application is shown;

[0042] Figure 4 A schematic diagram of a process for suppressing the DC component of each phase current in an embodiment of the present application is shown;

[0043] Figure 5 A schematic diagram of a process for detecting a DC component in an embodiment of the present application is shown;

[0044] Figure 6 A schematic diagram of an inverter control device in an embodiment of the present application is shown;

[0045] Figure 7 Another schematic diagram of the inverter control device in the embodiment of the present application is shown.

[0046] Among them, 101 is a positive bus, 102 is a negative bus, 200 is an inverter unit, 301 is a first-phase AC voltage output line, 302 is a second-phase AC voltage output line, 303 is a third-phase AC voltage output line, C1 is a first capacitor, C2 is a second capacitor, L is a first inductor, and Cf is a third capacitor;

[0047] 401 is a DC component detection module, 402 is an initial reference determination module, 403 is a target reference determination module, and 404 is a DC component control module. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, the word "exemplary" is used to mean "used as an example, illustration, or description". Any embodiment described in this application as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any person skilled in the art to implement and use the present invention. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present invention can be implemented without using these specific details. In other instances, well-known structures and processes are not elaborated in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0050] The embodiments of the present application provide an inverter control method, device, system, and storage medium, which are described in detail below.

[0051] First, before introducing the inverter control method of the present application, an inverter circuit to which the inverter control method of the present application is applied is first introduced. Figure 1 , Figure 1 A schematic diagram of an inverter circuit in an embodiment of the present application is shown, wherein the inverter circuit includes an input positive bus 101, a negative bus 102, an inverter unit 200, a first phase AC voltage output line 301, a second phase AC voltage output line 302 and a third phase AC voltage output line 303.

[0052] Specifically, one end of the positive bus 101 and the negative bus 102 is connected to a DC power supply, and the other end of the positive bus 101 and the negative bus 102 is connected to the inverter unit 200, so that the inverter unit 200 converts the DC voltage input by the DC power supply into a multi-phase AC voltage. Among them, a first capacitor C1 is connected between the positive bus 101 and the neutral point O, a second capacitor C2 is connected between the negative bus 102 and the neutral point O, and the neutral point O is connected to the neutral point N of the three-phase voltage of the power grid. The first capacitor C1 can be used as a positive bus capacitor, and the second capacitor C2 can be used as a negative bus capacitor to suppress the fluctuation of the input voltage of the positive bus 101 and the negative bus 102.

[0053] Exemplarily, the DC power source connected to the positive bus 101 and the negative bus 102 may include but is not limited to photovoltaic panel batteries such as monocrystalline silicon batteries, polycrystalline silicon batteries, amorphous silicon batteries, or energy storage batteries such as lead-acid batteries, lithium-ion batteries, sodium-sulfur batteries, nickel-hydrogen batteries, and nickel-cadmium batteries.

[0054] The inverter unit 200 can convert the DC voltage input by the DC power supply into a multi-phase AC voltage, so that the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 connected to the inverter unit 200 output a three-phase AC voltage. Generally, the inverter unit 200 includes a plurality of switching transistors (such as thyristors, IGBT tubes, etc.), and the output voltage waveform is adjusted by controlling the on and off states of the switching transistors, thereby realizing the conversion from DC to AC. Exemplarily, the inverter unit 200 may include but is not limited to a half-bridge inverter circuit, a full-bridge inverter circuit or a push-pull inverter circuit.

[0055] The first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 can be connected to the power grid, so as to merge the three-phase voltage outputted by the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 into the power grid. The first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 are respectively connected in series with a first inductor L, and the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 are respectively connected with a third capacitor Cf, and the first inductor L and the third capacitor Cf can be used as line inductance and filter capacitor outputted to the power grid, so as to eliminate the high frequency noise of the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303.

[0056] It can be understood that the above embodiment is a schematic diagram of the inverter circuit of the present application that exemplifies the conversion of DC voltage into three-phase voltage. In some possible embodiments, the inverter circuit can convert DC voltage into four-phase voltage.

[0057] Next, we will introduce the inverter control method of the present application. Figure 2 , Figure 2 A flow chart of an inverter control method in an embodiment of the present application is shown, wherein, in the process of converting direct current into alternating current through half-bus modulation, the inverter is used to output a multi-phase alternating current voltage according to the direct current voltage input by the positive bus 101 and the negative bus 102. The inverter control method of the present application can suppress the influence of the bus voltage deviation on the direct current component of each phase current in the unbalanced mode of the inverter, and the inverter control method includes:

[0058] Step S201, detecting the DC component of each phase current output by the inverter, and determining the average value of the DC component of the multi-phase current;

[0059] In some embodiments of the present application, the DC component of each phase current can be obtained by directly measuring the magnitude of each phase current and then calculating, for example, Figure 1 For example, the current magnitudes of the first-phase AC voltage output line 301, the second-phase AC voltage output line 302, and the third-phase AC voltage output line 303 can be measured by an analog-to-digital converter, and then the digital signal of each phase current is integrated and its average value is calculated to obtain the DC component. For another example, the DC component can be determined by separating the positive and negative half-cycle signals of each phase current in one cycle and calculating the area difference between the two. In some embodiments of the present application, the DC component of each phase current can be obtained by indirect measurement. For example, the current signals of the first-phase AC voltage output line 301, the second-phase AC voltage output line 302, and the third-phase AC voltage output line 303 can be filtered out of the AC signal and the DC signal can be retained. After the DC signal is converted by the analog-to-digital converter, the DC component of each phase current can be detected.

[0060] After obtaining the DC component of each phase current, the average value of the DC component of the multi-phase current can be determined. For example, when the inverter outputs a three-phase voltage, the DC components of the first phase AC voltage output line 301, the second phase AC voltage output line 302, and the third phase AC voltage output line 303 can be added together, and then divided by the number of phases 3 to obtain the average value of the DC component of the multi-phase current.

[0061] Step S202, determining an initial reference value corresponding to the bus voltage deviation according to the DC component average value and a preset reference value;

[0062] Specifically, the preset reference value is a target value for feedback control of the average value of the DC component of the multi-phase current, so that the average value of the DC component of the multi-phase current reaches the preset reference value after feedback control. Generally, the preset reference value is 0, so that the average value of the DC component of the multi-phase current is reduced to 0 through feedback control. It can be understood that those skilled in the art can also set the preset reference value according to actual needs, for example, setting the preset reference value to 0.1A, 0.2A, etc.

[0063] It should be noted that the unbalanced mode of the inverter refers to the control mode of the inverter when facing an asymmetric load or an unbalanced grid voltage. In the unbalanced mode, the bus voltage deviation will affect the DC component of each phase current of the multi-phase current. Therefore, the initial reference value corresponding to the bus voltage deviation is determined according to the average value of the DC component and the preset reference value. The deviation between the average value of the DC component and the preset reference value can be obtained, so that the DC component of each phase current can be feedback controlled in combination with the bus voltage difference in subsequent steps, thereby reducing the influence of the bus voltage deviation on the DC component of each phase current in the unbalanced mode of the inverter.

[0064] In some embodiments of the present application, the average value of the DC component and the preset reference value can be input into the corresponding controller to obtain the initial reference value. For example, the step of determining the initial reference value corresponding to the bus voltage deviation according to the average value of the DC component and the preset reference value includes: inputting the average value of the DC component and the preset reference value into the first proportional integral controller, so that the first proportional integral controller outputs the initial reference value. Since the first proportional integrator (PI controller) combines the two modes of proportional control (P) and integral control (I), the error can be quickly reduced by proportional control, and the steady-state error can be eliminated by integral control, so the dynamic response performance and stability of the DC component feedback control of each phase current can be improved.

[0065] It can be understood that using a PI controller to determine the initial reference value according to the DC component average value and the preset reference value is only an exemplary embodiment. In some possible embodiments, a PID controller may also be used to determine the initial reference value.

[0066] Step S203, determining a target reference value corresponding to the bus voltage deviation according to the output power of the inverter and the initial reference value;

[0067] It should be noted that the output power of the inverter can be calculated by measuring the current and voltage on the AC side of the inverter. The output power of the inverter can be positive or negative during operation. The positive or negative value of the target reference value is consistent with the positive or negative value of the inverter output power, and the absolute value of the target reference value is equal to the initial reference value. For example, when the inverter output power is positive, the initial reference value is assigned a positive value to obtain the target reference value; conversely, when the inverter output power is negative, the initial reference value is assigned a negative value to obtain the target reference value. Therefore, the sign of the target reference value can be made consistent with the inverter output power.

[0068] Step S204 : controlling the inverter according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current.

[0069] Specifically, the bus voltage difference can be determined by measuring the positive bus 101 voltage and the negative bus 102 voltage through an analog-to-digital converter and calculating the difference between the two. For example, the bus voltage difference can be determined by the difference between the positive bus 101 voltage and the negative bus 102 voltage; for another example, the bus voltage difference can be determined by the difference between the negative bus 102 voltage and the positive bus 101 voltage. After determining the target reference value and the bus voltage difference between the positive bus 101 and the negative bus 102, the inverter can be controlled according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current.

[0070] In some embodiments of the present application, the duty cycle of the PWM signal of the control switch in the inverter can be compensated according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value, so as to suppress the influence of the bus voltage deviation on the average size of the DC component by changing the duty cycle of the PWM signal. In some embodiments of the present application, the bus voltage difference can also be controlled according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value feedback, so as to suppress the DC component of each phase current by controlling the bus voltage difference.

[0071] It should be noted that, since the output power of the inverter has positive and negative values ​​during operation, as described above, the bus voltage difference is usually determined by the difference between the negative bus 102 voltage and the positive bus 101 voltage, so the bus voltage difference also has positive and negative values, and the initial reference value determined in step S202 has no positive or negative value. If the initial reference value is directly used in combination with the bus voltage difference to control the inverter, there may be a phenomenon of over-compensation or under-compensation of the DC component. In the embodiment of the present application, since the absolute value of the target reference value is equal to the initial reference value, and the positive and negative values ​​of the target reference value are consistent with the positive and negative values ​​of the inverter output power, the inverter can be accurately controlled according to the bus voltage difference and the target reference value to avoid positive and negative changes in the inverter output power, resulting in the inability to accurately suppress the bus voltage deviation on the DC component of each phase current.

[0072] In some embodiments of the present application, see Figure 3 , Figure 3 A schematic diagram of a process of controlling an inverter in an embodiment of the present application is shown, wherein the steps of controlling the inverter according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value include:

[0073] Step S301, determining a first output result according to the bus voltage difference and the target reference value;

[0074] Step S302, superimposing the first output result to the control loop output result of the inverter to determine a total output result;

[0075] Step S303 , determining the duty cycle of the control signal according to the total output result and the bus voltage, where the bus voltage includes at least one of the positive bus 101 voltage and the negative bus 102 voltage.

[0076] Specifically, the bus voltage difference and the target reference value can be input into the PI controller, the bus voltage difference is used as the actual measurement value of the PI controller, and the target reference value is used as the expected value of the PI controller, so that the PI controller can output a first output result according to the bus voltage difference and the target reference value. The control loop of the inverter refers to a loop for feedback control of the inverter AC side current. Generally, the control loop of the inverter can include but is not limited to a current loop control loop, a voltage loop control loop or a power loop control loop, so as to control the inverter unit 200 through the control loop of the inverter and realize the conversion between DC and AC.

[0077] It should be noted that the control loop output result of the inverter is used to calculate the duty cycle of the control signal. In the above embodiment, since the first output result is superimposed on the control loop output result of the inverter to determine the total output result, the duty cycle of the control signal is determined based on the total output result and the bus voltage. Then, the duty cycle of the control signal will be affected by the bus voltage difference and the target reference value, thereby achieving the purpose of suppressing the DC component of each phase current by changing the duty cycle of the control signal.

[0078] In some embodiments of the present application, in step S303, if the total output result is greater than zero, the duty cycle of the control signal can be determined according to the total output result and the voltage of the positive bus 101, and the duty cycle of the control signal is negatively correlated with the absolute value of the voltage of the positive bus 101. As an example, the duty cycle of the control signal can be calculated according to the following formula:

[0079] Duty=Ctrl_out / Vin+

[0080] Wherein, Duty is the duty cycle of the control signal, Ctrl_out is the total output result, and Vin+ is the positive bus 101 voltage.

[0081] In some embodiments of the present application, in step S303, if the total output result is less than zero, the duty cycle of the control signal can be determined according to the total output result and the voltage of the negative bus 102, and the duty cycle of the control signal is negatively correlated with the absolute value of the voltage of the negative bus 102. As an example, the duty cycle of the control signal can be calculated according to the following formula:

[0082] Duty=Ctrl_out / Vin-

[0083] Among them, Ctrl_out is the total output result, and Vin- is the negative bus 102 voltage.

[0084] It can be seen that the above-mentioned embodiment settles the duty cycle according to the positive and negative sign of the total output result in combination with different bus voltages, and in combination with the embodiment in which the positive and negative signs of the target reference value are consistent with the positive and negative signs of the inverter output power. The present application considers the positive and negative signs of the inverter output power in the feedback control, and selects the corresponding bus voltage when calculating the modulation ratio. Therefore, the bus voltage deviation can be better compensated, and the phenomenon of feedback control loop saturation can be avoided.

[0085] In some embodiments of the present application, see Figure 4 , Figure 4 A schematic diagram of a process for suppressing the DC component of each phase current in an embodiment of the present application is shown, wherein the inverter control method further includes:

[0086] Step S401, determining a second output result of each phase current according to the DC component of each phase current and the average value of the DC component;

[0087] Step S402: superimpose the second output result of each phase current onto the control loop output result of the inverter to determine a total output result.

[0088] It should be noted that when the inverter operates in a balanced mode, the average value of its DC component is 0; when the inverter operates in an unbalanced mode, due to load asymmetry or grid voltage imbalance, the average value of its DC component is not 0. The control process of the above embodiment is to control the average value of the DC component as the overall control target to be close to the preset reference value (0) to achieve the DC component of each phase current, but there may be a phenomenon that the DC component of each phase current is not zero. For example, after the inverter is controlled by the above embodiment, the DC components of the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 may be 0.8A, -0.5A, and -0.3A, respectively. The average value of the DC component is zero, but the DC component of each phase current is not zero. Therefore, the DC component of each phase current needs to be further feedback controlled.

[0089] In the above embodiment, after the DC component and the average value of the DC component of each phase current are detected, the second output result of each phase current can be determined, and the second output result of each phase current can be superimposed on the control loop output result of the inverter to determine the total output result. Since the total output result not only includes the first output result corresponding to the average value of the DC component, but also includes the second output result corresponding to the DC component of each phase current, the duty cycle of the control signal is determined according to the bus voltage of the total output result. Not only can the average value of the DC component be controlled as the overall control target to be close to the preset reference value (0), but the DC component of each phase current can also be controlled to be close to the average value of the DC component. Since the average value of the DC component will eventually be close to 0, the DC component of each phase current will eventually be close to 0, which is conducive to better suppressing the DC component of each phase current.

[0090] In some embodiments of the present application, the DC component of each phase current and the average value of the DC component can be input into a PI controller, the DC component of each phase current is used as the actual measurement value of the PI controller, and the average value of the DC component is used as the expected value of the PI controller. Therefore, the second output result of each phase current can be determined by the PI controller based on the DC component of each phase current and the average value of the DC component.

[0091] It can be understood that in some possible embodiments, the second output result of each phase current can also be determined according to the DC component of each phase current and the average value of the DC component by other controllers, such as a PID controller.

[0092] In some embodiments of the present application, see Figure 5 , Figure 5 A schematic diagram of a process for detecting a DC component in an embodiment of the present application is shown, wherein the step of detecting a DC component of each phase current output by the inverter includes:

[0093] Step S501, determining a measurement error of a detection circuit, the detection circuit being used to read a DC measurement result of each phase current output by the inverter;

[0094] Step S502: determining the DC component of each phase current output by the inverter according to the measurement error of the detection circuit and the DC measurement result of each phase current.

[0095] It should be noted that the detection circuit usually includes a filter and an analog-to-digital converter. The filter can filter out the AC signal of each phase current and retain the DC component, and the analog-to-digital converter can measure the DC component. Due to differences in circuit manufacturing, the analog-to-digital converter usually has measurement errors, such as jitter errors caused by the offset voltage of the operational amplifier in the analog-to-digital converter. Usually, the measurement error of the detection circuit needs to be achieved by secondary gain calibration. For example, the DC component of each phase current can be calculated according to the following formula:

[0096] I dc (t) = (ADC Raw -ADC offset )*Ratio*Gain

[0097] Among them, I dc (t) is the DC component of each phase current, ADC Raw The DC measurement result of each phase current, ADC offset is the measurement error of the detection circuit, Ratio is the proportional gain of the measurement circuit, and Gain is the calibration gain of the measurement circuit.

[0098] Due to circuit manufacturing differences, the measurement error of the detection circuit ADC offset It is not a fixed value, so it is usually necessary to adjust the calibration gain Gain of the measurement circuit to ensure the accuracy of the measurement result. For example, for a current of 1.1A, if the measurement result is 1A, the calibration gain Gain can be set to 1.1, thereby calibrating the measurement result to 1.1A. However, this method requires external equipment (such as a high-precision voltage signal output device or a high-precision current signal output device) to perform a secondary calibration on the calibration gain Gain.

[0099] In the above embodiment, since the measurement error of the detection circuit is determined in advance, that is, the measurement error ADC in the above formula offset is a known value, so the DC component of each phase current output by the inverter can be determined using the above formula according to the measurement error of the detection circuit and the DC measurement result of each phase current, without the need to use external equipment to perform secondary calibration on the calibration gain Gain of the measurement circuit.

[0100] In some embodiments of the present application, the step of determining the measurement error of the detection circuit includes: when the inverter is not working and the AC side of the inverter is connected to the power grid, measuring the current measurement results of the AC side of the inverter multiple times; and determining the measurement error of the detection circuit based on the current measurement results of the multiple inverters.

[0101] It should be noted that when the inverter is not working, if the relay controlling the inverter to access the grid is energized, the AC side of the inverter is connected to the grid, and the DC components in the first-phase AC voltage output line 301, the second-phase AC voltage output line 302, and the third-phase AC voltage output line 303 are actual values ​​under the actual operation of the grid line. Therefore, the detection circuit performs multiple measurements on the AC side of the inverter to obtain the current measurement result corresponding to the actual value under the actual operation of the grid line. Each current measurement result is the difference between the actual value under the actual operation of the grid line and the measurement error ADC. offsetThe sum of the current and the current is the sum of the current and the current. Since the power grid is an AC signal, its average value is 0. Therefore, the average value of multiple current measurement results obtained by multiple measurements is the measurement error ADC of the measurement circuit. offset , for example, the measurement error of the measurement circuit ADC offset It can be calculated as follows:

[0102] ADC offset (Avg) = (ADC Raw (t1)+ADC Raw (t2)+…+ADC Raw (t n )) / n

[0103] Among them, ADC Raw (t1), ADC Raw (t2)...ADC Raw (t n ) are the current measurement results of the AC side of the inverter multiple times.

[0104] It can be seen that the present application relies on the power grid as a signal input to determine the measurement error of the detection circuit, which not only ensures the measurement accuracy of the DC component of each phase current, but also eliminates the need to use external equipment (such as high-precision voltage signal output equipment or high-precision voltage signal output equipment) to perform secondary calibration on the calibration gain Gain.

[0105] Furthermore, in order to better implement the inverter control method in the embodiment of the present application, the present application also provides an inverter control device, see Figure 6 , Figure 6 A schematic diagram of an inverter control device in an embodiment of the present application is shown, wherein the inverter control device includes a DC component detection module 401, an initial reference determination module 402, a target reference determination module 403 and a DC component control module 404.

[0106] Specifically, the DC component detection module 401 is used to detect the DC component of each phase current output by the inverter, and determine the average value of the DC component of the multi-phase current. For example, the DC component detection module 401 can filter out the AC signal of the current of the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 through a filter and retain the DC signal, and after converting the DC signal through an analog-to-digital converter, the DC component of each phase current can be obtained. After obtaining the DC component of each phase current, the average value of the DC component of the multi-phase current can be determined. For example, when the inverter outputs a three-phase voltage, the DC components of the first phase AC voltage output line 301, the second phase AC voltage output line 302 and the third phase AC voltage output line 303 can be added, and then divided by the number of phases 3 to obtain the average value of the DC component of the multi-phase current.

[0107] The initial reference determination module 402 is used to determine the initial reference value corresponding to the bus voltage deviation according to the DC component average value and the preset reference value. In some embodiments of the present application, the initial reference determination module 402 may include a controller, and the DC component average value and the preset reference value may be input into the corresponding controller to obtain the initial reference value. For example, see Figure 7 , Figure 7 Another schematic diagram of the inverter control device in an embodiment of the present application is shown, where the initial reference determination module 402 includes a PI controller, and the DC component average value and a preset reference value are input into the PI controller so that the first proportional-integral controller outputs an initial reference value.

[0108] The target reference determination module 403 is used to determine the target reference value corresponding to the bus voltage deviation according to the output power of the inverter and the initial reference value, wherein the absolute value of the target reference value is equal to the initial reference value, and the positive and negative signs of the target reference value are consistent with the positive and negative signs of the inverter output power. For example, when the inverter output power is a positive value, the initial reference value is assigned a positive value to obtain the target reference value; conversely, when the inverter output power is a negative value, the initial reference value is assigned a negative value to obtain the target reference value, so that the sign of the target reference value can be consistent with the inverter output power.

[0109] The DC component control module 404 is used to control the inverter according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current. In some embodiments of the present application, the duty cycle of the PWM signal of the control switch in the inverter can be compensated according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value, so as to suppress the influence of the bus voltage deviation on the average size of the DC component by changing the duty cycle of the PWM signal.

[0110] For example, continue to see Figure 7 The bus voltage difference and the target reference value are input into the PI controller, and the PI controller outputs a first output result, which is superimposed on the output results of the voltage loop and the power loop of the inverter to obtain a total output result. If the total output result is greater than zero, the duty cycle of the control signal can be determined according to the ratio of the total output result to the positive bus 101 voltage; conversely, if the total output result is less than zero, the duty cycle of the control signal can be determined according to the ratio of the total output result to the negative bus 102 voltage, and finally the control signal is output to reduce the control of the inverter unit 200.

[0111] In some embodiments of the present application, see Figure 7, the DC component of each phase current and the average value of the DC component can be input into the PI controller, and the second output result of each phase current can be determined according to the DC component of each phase current and the average value of the DC component through the PI controller, and then the second output result can be superimposed on the output results of the voltage loop and the power loop of the inverter to obtain the total output result. Since the total output result not only includes the first output result corresponding to the average value of the DC component, but also includes the second output result corresponding to the DC component of each phase current, the duty cycle of the control signal is determined according to the bus voltage of the total output result, which can not only suppress the influence of the bus voltage deviation on the average value of the DC component, but also suppress the DC component of each phase current.

[0112] It should be understood that Figure 6 The device and its modules shown can be implemented in various ways. For example, in some embodiments, the device and its modules can be implemented by hardware, software or a combination of software and hardware. Among them, the hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or a dedicated design hardware. Those skilled in the art will understand that the above-mentioned method and system can be implemented using computer executable instructions and / or included in a processor control code, for example, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The system and its modules of the present application can not only be implemented by hardware circuits such as ultra-large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., but can also be implemented by software such as executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software (for example, firmware).

[0113] Furthermore, an embodiment of the present application also provides an inverter control system, which includes a memory and a processor. Those skilled in the art can understand that the inverter control system may include more or fewer components, or combine certain components, or arrange the components differently. Among them:

[0114] The processor is the control center of the system, which uses various interfaces and lines to connect various parts of the entire system, and executes various functions of the system and processes data by running or executing software programs and / or modules stored in the memory, and calling data stored in the memory, so as to monitor the system as a whole. Optionally, the processor may include one or more processing cores; the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. Preferably, the processor may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface and application programs, etc., and the modem processor mainly processes wireless communications. It is understandable that the above-mentioned modem processor may not be integrated into the processor.

[0115] The memory can be used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the target detection system, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices. Accordingly, the memory may also include a memory controller to provide the processor with access to the memory.

[0116] Furthermore, an embodiment of the present invention further provides a computer-readable storage medium, which may include: a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc. A computer program is stored thereon, and the computer program is loaded by a processor to execute the steps in any inverter control method provided in an embodiment of the present invention. For example, the computer program may be loaded by a processor to execute the following steps:

[0117] Detecting the DC component of each phase current output by the inverter and determining the average value of the DC component of the multi-phase current;

[0118] Determine an initial reference value corresponding to the bus voltage deviation according to the average value of the DC component and the preset reference value;

[0119] Determine the target reference value corresponding to the bus voltage deviation according to the output power of the inverter and the initial reference value;

[0120] Controlling the inverter according to the bus voltage difference between the positive bus 101 and the negative bus 102 and the target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current;

[0121] The absolute value of the target reference value is equal to the initial reference value, and the positive and negative values ​​of the target reference value are consistent with the positive and negative values ​​of the inverter output power.

[0122] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0123] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0124] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0125] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0126] The above is a detailed introduction to an inverter control method, device, system and storage medium provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. An inverter control method, characterized in that: The inverter is used to output a multi-phase AC voltage according to a DC voltage input by a positive bus and a negative bus, and the method comprises: Detecting the DC component of each phase current output by the inverter, and determining an average value of the DC components of the multi-phase current; Determining an initial reference value corresponding to the bus voltage deviation according to the DC component average value and a preset reference value; Determining a target reference value corresponding to a bus voltage deviation according to the output power of the inverter and the initial reference value; controlling the inverter according to the bus voltage difference between the positive bus and the negative bus and the target reference value to suppress the influence of the bus voltage deviation on the DC component of each phase current; The absolute value of the target reference value is equal to the absolute value of the initial reference value, and the positive and negative signs of the target reference value are consistent with the positive and negative signs of the inverter output power.

2. The inverter control method according to claim 1, characterized in that: The step of controlling the inverter according to the bus voltage difference between the positive bus and the negative bus and the target reference value comprises: Determining a first output result according to the bus voltage difference and the target reference value; adding the first output result to the control loop output result of the inverter to determine a total output result; The duty cycle of the control signal is determined according to the total output result and a bus voltage, wherein the bus voltage includes at least one of the positive bus voltage and the negative bus voltage.

3. The inverter control method according to claim 2, characterized in that: The step of determining the duty cycle of the control signal according to the total output result and the bus voltage comprises: When the total output result is greater than zero, determining the duty cycle of the control signal according to the total output result and the positive bus voltage, and the duty cycle of the control signal is negatively correlated with the absolute value of the positive bus voltage; When the total output result is less than zero, the duty cycle of the control signal is determined according to the total output result and the negative bus voltage, and the duty cycle of the control signal is negatively correlated with the absolute value of the negative bus voltage.

4. The inverter control method according to claim 3, characterized in that: The method further comprises: Determine a second output result of each phase current according to a DC component of each phase current and an average value of the DC component; The second output result of each phase current is added to the control loop output result of the inverter to determine the total output result.

5. The inverter control method according to claim 1, characterized in that: The step of detecting the DC component of each phase current output by the inverter comprises: Determining a measurement error of a detection circuit, wherein the detection circuit is used to read a DC measurement result of each phase current output by the inverter; The DC component of each phase current output by the inverter is determined according to the measurement error of the detection circuit and the DC measurement result of each phase current.

6. The inverter control method according to claim 5, characterized in that: The step of determining the measurement error of the detection circuit comprises: When the inverter is not working and the AC side of the inverter is connected to the power grid, measuring the current measurement results of the AC side of the inverter multiple times; The measurement error of the detection circuit is determined according to multiple current measurement results of the inverter AC side.

7. The inverter control method according to claim 1, characterized in that: The step of determining the initial reference value corresponding to the bus voltage deviation according to the DC component average value and the preset reference value comprises: The DC component average value and a preset reference value are input into a first proportional-integral controller, so that the first proportional-integral controller outputs the initial reference value.

8. An inverter control device, characterized in that: The inverter is used to output a multi-phase AC voltage according to the DC voltage input by the positive bus and the negative bus, and the device includes: A DC component detection module, the DC component detection module is used to detect the DC component of each phase current output by the inverter and determine the average value of the DC component of the multi-phase current; An initial reference determination module, the initial reference determination module is used to determine an initial reference value corresponding to the bus voltage deviation according to the DC component average value and a preset reference value; a target reference determination module, the target reference determination module being used to determine a target reference value corresponding to a bus voltage deviation according to an output power of the inverter and the initial reference value; a DC component control module, the DC component control module being used to control the inverter according to the bus voltage difference between the positive bus and the negative bus and the target reference value, so as to suppress the influence of the bus voltage deviation on the DC component of each phase current; The absolute value of the target reference value is equal to the absolute value of the initial reference value, and the positive and negative signs of the target reference value are consistent with the positive and negative signs of the inverter output power.

9. An inverter control system, characterized in that: The invention comprises a memory and a processor, wherein the memory stores a computer program, and the processor is used to run the computer program in the memory to execute the steps in the inverter control method according to any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor to execute the steps in the inverter control method according to any one of claims 1 to 7.

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