Bus voltage balance control method and device, inverter and storage medium

Abstract

The invention relates to a bus voltage balance control method and device, an inverter and a storage medium, the method is applied to the inverter, and the method comprises the following steps: obtaining an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage and / or a control quantity of the inverter; and generating an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, and controlling the inverter to work according to the adjusted control quantity so as to realize bus voltage balance, so that the cost and loss of the system can be reduced, and the method is not influenced by a control method of a voltage loop and a current loop in the system, and is suitable for large-scale popularization and application. And meanwhile, the stability and the effect of bus voltage balance can be improved, and stable operation of the system can be ensured.

Description

Technical Field

[0001] The present application relates to the technical field of inverters, and in particular to a bus voltage balance control method, device, inverter and storage medium. Background Art

[0002] Inverters can be divided into full-bridge inverter circuits and half-bridge inverter circuits according to different circuit structures. Half-bridge inverters are widely used in industrial applications due to their simple circuits and relatively few required power devices. However, the DC side of the half-bridge inverter includes two series capacitors. The total voltage on the series capacitors is equal to the voltage between the positive and negative busbars. During operation, the voltage balance on the two capacitors must be controlled. Under normal working conditions, it is difficult to achieve voltage balance, especially under high power conditions. The situation is even worse. The voltage fluctuations on the two capacitors are large, which can easily cause distortion of the inverter's output voltage and output current, and even seriously affect the stability of the system.

[0003] An effective solution needs to be proposed to solve the problem of unbalanced inverter bus voltage. Summary of the invention

[0004] In this embodiment, a bus voltage balance control method, device, inverter and storage medium are provided to achieve bus voltage balance.

[0005] In a first aspect, a bus voltage balancing control method is provided in this embodiment. The method is applied to an inverter, and the method includes:

[0006] Obtaining an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage and / or a control variable of an inverter;

[0007] Based on the error adjustment value and the electrical parameters of the inverter, an adjusted control amount is generated, and the inverter is controlled to operate according to the adjusted control amount to achieve bus voltage balance.

[0008] In some embodiments, obtaining the error adjustment value based on the voltage difference between the positive bus voltage and the negative bus voltage and / or the control amount of the inverter includes:

[0009] Based on the voltage difference between the positive bus voltage and the negative bus voltage, obtaining a DC component of the bus voltage difference;

[0010] Based on the control amount of the inverter, obtaining a DC component of the control amount;

[0011] The error adjustment value is determined based on a DC component of the bus voltage difference and a DC component of the controlled variable.

[0012] In some embodiments, the electrical parameter of the inverter includes an inductor current, and obtaining a DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage includes:

[0013] Obtaining a correction coefficient based on the inductor current and the flow direction of energy in the inverter;

[0014] Based on the voltage difference between the positive bus voltage and the negative bus voltage and the correction coefficient, a DC component of the bus voltage difference is obtained.

[0015] In some embodiments, obtaining a DC component of a bus voltage difference based on a voltage difference between the positive bus voltage and the negative bus voltage includes:

[0016] A voltage difference between the positive bus voltage and the negative bus voltage is limited, and a DC component of the bus voltage difference is obtained according to the voltage difference after the limit.

[0017] In some of the embodiments, the control variable of the inverter is a duty cycle of a power switch tube of the inverter or a modulation wave for controlling the duty cycle of the power switch tube.

[0018] In some embodiments, the electrical parameters of the inverter include an inductor current and an AC side voltage, and generating the adjusted control amount based on the error adjustment value and the electrical parameters of the inverter includes:

[0019] Based on the error adjustment value, the inductor current and the AC side voltage of the inverter, an adjusted control amount is generated through repeated control or double closed-loop control of a voltage outer loop and a current inner loop.

[0020] In some embodiments, obtaining the error adjustment value based on the voltage difference between the positive bus voltage and the negative bus voltage and / or the control amount of the inverter includes:

[0021] Based on the voltage difference between the positive bus voltage and the negative bus voltage, a DC component of the bus voltage difference is obtained, where the DC component of the bus voltage difference is the error adjustment value; or

[0022] Based on the control amount of the inverter, a DC component of the control amount is obtained, and the DC component of the control amount is the error adjustment value.

[0023] In a second aspect, a bus voltage balancing control device is provided in this embodiment. The device is applied to an inverter, and the device includes:

[0024] A compensation module, used for obtaining an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage and / or a control amount of an inverter;

[0025] The closed-loop control module is used to generate an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, and control the inverter to operate according to the adjusted control quantity to achieve bus voltage balance.

[0026] In a third aspect, an inverter is provided in this embodiment, wherein the inverter comprises an inverter circuit for inverting a DC bus voltage into an AC voltage, and a bus voltage balancing control device as described in the second aspect.

[0027] In a fourth aspect, a readable storage medium is provided in this embodiment, on which a program is stored, and when the program is executed by a processor, the steps of the bus voltage balance control method described in the first aspect are implemented.

[0028] Compared with the related art, a bus voltage balancing control method is provided in the present embodiment, by obtaining an error adjustment value based on the voltage difference between the positive bus voltage and the negative bus voltage and / or the control amount of the inverter, that is, the positive and negative bus voltage difference and / or the inverter control amount are used as two input variables for error adjustment, and the error adjustment value is obtained according to at least one of the two input variables; by generating an adjusted control amount based on the error adjustment value and the electrical parameters of the inverter, and controlling the inverter to work according to the adjusted control amount to achieve bus voltage balance, this method does not change the circuit structure, can reduce the cost and loss of the system, and this method is not affected by the control method of the voltage loop and the current loop in the system, has good dynamic performance, and can improve the stability and effect of the bus voltage balance, thereby ensuring that the system can operate stably.

[0029] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 is a flow chart of a bus voltage balancing control method according to some embodiments of the present application;

[0032] Figure 2 is a schematic diagram of a circuit topology of an inverter according to some embodiments of the present application;

[0033] Figure 3 is a schematic diagram of a circuit topology of an inverter according to some other embodiments of the present application;

[0034] Figure 4is a structural block diagram of a controller for executing a bus voltage balancing control method in some embodiments of the present application;

[0035] Figure 5 is a flow chart of obtaining an error adjustment value based on a positive and negative bus voltage difference and a control amount of an inverter in some embodiments of the present application;

[0036] Figure 6 is a flow chart of obtaining a DC component of a bus voltage difference based on a positive and negative bus voltage difference in some embodiments of the present application;

[0037] Figure 7 is a flow chart of generating an adjusted control quantity based on an error adjustment value and an electrical parameter in some embodiments of the present application;

[0038] Figure 8 is a schematic diagram of the structure of an inverter of some specific embodiments of the present application;

[0039] Fig. 9 It is a structural block diagram of a bus voltage balancing control device in some embodiments of the present application. DETAILED DESCRIPTION

[0040] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0041] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the", "these" and the like in this application do not represent quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether directly or indirectly. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. Usually, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0042] In this embodiment, a bus voltage balance control method is provided. Figure 1 is a flow chart of a bus voltage balance control method according to some embodiments of the present application. Figure 1 As shown, the process includes the following steps:

[0043] Step S201: acquiring an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage and / or a control variable of an inverter.

[0044] A half-bridge inverter circuit is a topology structure of an inverter circuit. The bus voltage balance control method of this embodiment can be used for various half-bridge inverter circuits, such as a T-type multi-level circuit or an I-type multi-level circuit.

[0045] Figure 2 is a schematic diagram of the circuit topology of the inverter in some embodiments of the present application, such as Figure 2 As shown, it includes an inverter circuit and a filter circuit. The inverter circuit includes capacitors C1, C2 and power switch tubes G1, G2; the filter circuit includes an inductor L and a capacitor C3. The connection midpoint of capacitors C1 and C2 is the neutral point O. By controlling the on and off of the power switch tubes G1 and G2, the DC bus voltage U bus Invert to AC voltage u invWhen the voltage across capacitor C1 U busP The voltage U across capacitor C2 busN When unbalanced, the AC voltage and current output by the inverter are easily distorted.

[0046] In this embodiment, the positive bus voltage refers to the voltage U across the capacitor C1. busP , the negative bus voltage refers to the voltage U across the capacitor C2 busN During the operation of the inverter, the positive bus voltage U of the inverter can be obtained in real time. busP With negative bus voltage U busN The pressure difference between the two is calculated.

[0047] Usually, closed-loop control is used to control the on and off of the power switch tube. According to actual needs, single closed-loop control or dual closed-loop control of voltage loop and current loop can be used. Specific control methods may include PID control, repetitive control, etc.

[0048] The control quantity of the inverter can be the duty cycle of any one of the power switch tubes G1 and G2 or the modulation wave used to control the duty cycle of the power switch tube. Those skilled in the art can understand that Figure 2 The circuit topology of the inverter shown is for illustration only and does not limit the circuit topology of the inverter. For example, the layout and number of power switches can be different from the Figure 2 The layout and number of power switches shown are different.

[0049] Figure 3 is a schematic diagram of the circuit topology of the inverter of other embodiments of the present application, such as Figure 3 As shown, Figure 2 The difference is that the inverter circuit is a T-type three-level circuit, including capacitors C1, C2 and power switch tubes Q1-Q4, wherein the power switch tubes Q1-Q4 are connected in series between the positive bus and the negative bus, and the power switch tubes Q2 and the power switch tubes Q3 are connected in series between the neutral point O and the series node of the power switch tubes Q1 and the power switch tubes Q4. Other similarities are not repeated here.

[0050] In this embodiment, according to the positive bus voltage U busP and negative bus voltage U busN The voltage difference between the positive bus voltage and the positive bus voltage U busP and negative bus voltage U busN The voltage difference between the positive bus voltage and the control quantity of the inverter is combined to obtain the error adjustment value. The error adjustment value can be input as a variable into the closed-loop control system of the inverter to achieve the positive bus voltage U busP and negative bus voltage UbusN voltage balance between.

[0051] Step S202: generating an adjusted control amount based on the error adjustment value and the electrical parameters of the inverter, and controlling the inverter to operate according to the adjusted control amount to achieve bus voltage balance.

[0052] The error adjustment value is input as a variable into the closed-loop control system of the inverter. The input variables of the closed-loop control system may also include the electrical parameters of the inverter, such as the AC side voltage and inductor current of the inverter. After these variables are input into the closed-loop control system, the closed-loop control system adjusts and outputs the adjusted control quantity, which may be the duty cycle of the power switch tube or the modulation wave used to control the duty cycle of the power switch tube. Based on the adjusted control quantity, the conduction and disconnection of each power switch tube in the inverter circuit are controlled, which can effectively adjust the voltage on the two capacitors in series and achieve bus voltage balance.

[0053] Through steps S201 to S202, an error adjustment value is obtained based on the voltage difference between the positive bus voltage and the negative bus voltage and / or the control amount of the inverter, that is, the positive and negative bus voltage difference and / or the inverter control amount are used as two input variables for error adjustment, and the error adjustment value is obtained according to at least one of the two input variables; based on the error adjustment value and the electrical parameters of the inverter, an adjusted control amount is generated, and the inverter is controlled to work according to the adjusted control amount to achieve bus voltage balance. This method does not require the addition of hardware circuits or changes in circuit structure, can reduce system costs and losses, and is not affected by the control methods of the voltage loop and the current loop in the closed-loop control system, has good dynamic performance and fast response speed, and ensures that the system can operate stably.

[0054] The bus voltage balance control method provided in the embodiment of the present application can be executed in a terminal, a computer, or a similar computing device, or in a controller of an inverter. The controller, terminal, computer, etc. can receive, process and send relevant data such as electrical parameters of the inverter.

[0055] When this method is applied to the inverter controller, Figure 4 1 is a block diagram of a controller of an inverter for executing a bus voltage balancing control method in some embodiments of the present application. Figure 4 As shown, the controller of the inverter may include one or more ( Figure 4 Only one is shown in the figure) a processor 102 and a memory 104 for storing data, wherein the processor 102 may include but is not limited to processing devices such as a digital signal processor DSP, a microprocessor MCU or a programmable logic device FPGA.

[0056] The inverter may be a single-phase inverter, a split-phase inverter or a three-phase inverter, and each phase may be controlled separately; the inverter may be an energy storage inverter or a micro inverter, etc. A person skilled in the art may understand that Figure 4 The structure shown is only for illustration and does not limit the structure of the above controller. Figure 4 More or fewer components as shown, or with Figure 4 Different configurations shown.

[0057] The memory 104 can be used to store computer programs, data and instructions, for example, software programs and modules of application software, such as the computer program corresponding to the bus voltage balance control method in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, to implement the above method. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some embodiments, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0058] In some embodiments, Figure 5 is a flow chart of obtaining an error adjustment value based on the voltage difference between the positive and negative busbars and the control amount of the inverter in some embodiments of the present application, such as Figure 5 As shown, the process includes the following steps:

[0059] Step S401, based on the voltage difference between the positive bus voltage and the negative bus voltage, a DC component of the bus voltage difference is obtained.

[0060] In the inverter circuit, the controller controls the power switch tubes to turn on and off to perform inversion, causing capacitors C1 and C2 to charge and discharge alternately, so the positive bus voltage U busP and negative bus voltage U busN It rises and falls alternately, and the pressure difference between the two fluctuates periodically.

[0061] When the positive and negative bus voltages are in an ideal balanced state, the voltage difference between the positive bus voltage and the negative bus voltage fluctuates regularly between the positive voltage and the negative voltage, and the DC component is 0 in one AC cycle. In actual applications, since the positive and negative bus voltages are not completely balanced, the DC component of the bus voltage difference is usually not 0.

[0062] In some specific embodiments, for example, the DC component of the bus voltage difference may be obtained by integrating the bus voltage difference.

[0063] Step S402: acquiring a DC component of the control variable based on the control variable of the inverter.

[0064] The control quantity of the inverter can be the duty cycle of any power switch tube in the inverter circuit or the modulation wave used to control the duty cycle of the power switch tube. By integrating the control quantity, the DC component of the control quantity can be obtained.

[0065] Step S403: determining an error adjustment value based on the DC component of the bus voltage difference and the DC component of the control variable.

[0066] In this step, the difference between the DC component of the bus voltage difference and the DC component of the controlled variable is used as the error adjustment value.

[0067] Through steps S401 to S403, by obtaining the DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage, the control gain can be increased, and the balancing effect of the bus voltage can be enhanced when the inverter is connected to a positive and negative half-wave asymmetric load; by obtaining the DC component of the control quantity based on the control quantity of the inverter, the output of the closed-loop control system is fed back in real time, the dynamic response of the closed-loop control system is improved, and the balancing effect of the bus midpoint can be enhanced when the inverter is connected to an inductive load, and the switching of various loads can be quickly responded to; further, based on the DC component of the bus voltage difference and the DC component of the control quantity, an error adjustment value is determined, and the adjusted control quantity of the inverter is generated through the error adjustment value to achieve bus voltage balance, improve the dynamic performance of bus voltage balance and achieve rapid response.

[0068] In some embodiments, Figure 6 is a flow chart of obtaining the DC component of the bus voltage difference based on the positive and negative bus voltage difference in some embodiments of the present application, such as Figure 6 As shown, the process includes the following steps:

[0069] Step S501, obtaining a correction coefficient based on the inductor current and the flow direction of energy in the inverter.

[0070] The inductor current refers to the current flowing through the inductor L in the filter circuit of the inverter. In some embodiments, the correction coefficient can be obtained by the following steps:

[0071] Step S5011, sampling the inductor current of one AC cycle, and obtaining the effective value of the inductor current by RMS calculation;

[0072] Step S5012, normalizing the effective value of the inductor current to determine the value of the correction coefficient;

[0073] The per-unit value obtained by the normalization process is the ratio of the effective value of the inductor current to the reference value of the inductor current, and the range is [0, 1]. The reference value of the inductor current can be calculated by the rated power of the inverter and the DC bus voltage.

[0074] Step S5013, determining the sign of the correction coefficient according to the flow direction of energy in the inverter;

[0075] If the inverter is an energy storage inverter, or the energy on the DC side and the AC side of the inverter can flow in both directions (i.e., bidirectional power conversion can be performed), the sign of the correction coefficient needs to be determined according to the direction of energy flow. When flowing from the DC side to the AC side (i.e., inversion), the sign of the correction coefficient can be defined as positive, and when flowing from the AC side to the DC side (i.e., rectification), the sign of the correction coefficient is negative. If the DC side and the AC side of the inverter cannot flow in both directions, there is no need to consider the sign of the correction coefficient, and the correction coefficient is a positive value.

[0076] The correction coefficient is obtained by multiplying the sign of the correction coefficient determined in step S5013 by the value of the correction coefficient determined in step S5012.

[0077] Step S502: based on the voltage difference between the positive bus voltage and the negative bus voltage and the correction coefficient, a DC component of the bus voltage difference is obtained.

[0078] The voltage difference between the positive bus voltage and the negative bus voltage is integrated to obtain the corresponding initial value of the DC component, and the initial value of the DC component is multiplied by the correction coefficient to obtain the corrected DC component of the bus voltage difference.

[0079] Through steps S501 to S502, a correction coefficient is obtained based on the inductor current, and the effective value of the inductor current is used to correct the amplitude of the DC component of the bus voltage difference, thereby increasing the dynamic response and reducing the bus voltage difference overshoot at low current, thereby improving the stability and effect of bus voltage balancing.

[0080] In some embodiments, a specific method for obtaining a DC component of a bus voltage difference based on a voltage difference between a positive bus voltage and a negative bus voltage is also provided. The method includes:

[0081] The voltage difference between the positive bus voltage and the negative bus voltage is limited, and the DC component of the bus voltage difference is obtained according to the voltage difference after limiting.

[0082] The voltage difference between the positive bus voltage and the negative bus voltage is compared with the preset voltage difference threshold. The threshold can be the upper and lower threshold values ​​of the voltage difference interval, or the unilateral threshold value. When the voltage difference between the positive bus voltage and the negative bus voltage is between the upper and lower limits, the voltage difference between the positive bus voltage and the negative bus voltage is integrated to obtain the DC component of the bus voltage difference; when the voltage difference between the positive bus voltage and the negative bus voltage is greater than the upper limit value, the upper limit value is integrated to obtain the DC component of the bus voltage difference; when the voltage difference between the positive bus voltage and the negative bus voltage is less than the lower limit value, the lower limit value is integrated to obtain the DC component of the bus voltage difference.

[0083] The bus voltage balancing control method of the present embodiment limits the voltage difference between the positive bus voltage and the negative bus voltage, obtains the DC component of the bus voltage difference based on the voltage difference after limiting, thereby protecting the closed-loop control system of the inverter and avoiding instability of the closed-loop control system due to excessive feedforward value when the voltage difference between the positive bus voltage and the negative bus voltage is too large (for example, when the voltage on the DC side capacitor is just established when the power is just turned on).

[0084] In some embodiments, a specific method for generating an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter is also provided. The method includes:

[0085] Based on the error adjustment value, the inductor current and the AC side voltage of the inverter, an adjusted control quantity is generated through repeated control or double closed-loop control of a voltage outer loop and a current inner loop.

[0086] Specifically, the error adjustment value is input into the closed-loop control system of the inverter, and the input variables of the closed-loop control system also include the electrical parameters of the inverter, and the electrical parameters include the inductor current and the AC side voltage of the inverter. The closed-loop control system can use repetitive control or a dual closed-loop control method of voltage outer loop and current inner loop to generate an adjusted control quantity according to the error adjustment value, the inductor current and the AC side voltage of the inverter.

[0087] For the dual closed-loop control system with voltage outer loop and current inner loop, Figure 7 is a flow chart of generating an adjusted control quantity based on an error adjustment value, an inductor current, and an AC side voltage of an inverter in some embodiments of the present application, such as Figure 7 As shown, the following steps are included:

[0088] Step S601, obtaining an AC voltage error value based on a difference between a preset reference voltage and an effective value of an AC side voltage of an inverter.

[0089] Specifically, the AC side voltage of the inverter sampled in several cycles is subjected to RMS processing to obtain an effective value of the AC side voltage, and a preset reference voltage is subtracted from the effective value of the AC side voltage to obtain an AC voltage error value.

[0090] Step S602: acquiring an AC voltage instantaneous reference value based on the AC voltage error value and the error adjustment value.

[0091] After the AC voltage error value is processed by proportional-integral, the processed AC voltage error value is added to the error adjustment value obtained in the above embodiment to obtain an AC voltage instantaneous reference value.

[0092] Step S603, obtaining an output current reference value based on the AC voltage instantaneous reference value and the instantaneous value of the AC side voltage.

[0093] Obtain the AC side voltage u of the inverter by sampling inv The instantaneous value of the AC voltage is obtained by subtracting the instantaneous value of the AC side voltage from the instantaneous value of the AC voltage. The difference is processed by proportional-integral to obtain the output current reference value of the inverter.

[0094] Step S604: acquiring an adjusted control variable based on the output current reference value and the inductor current.

[0095] The inductor current in the inverter is obtained by sampling, and the output current reference value is subtracted from the inductor current to obtain a current error value. The current error value is processed proportionally or proportional-integral to obtain an adjusted control quantity. The control quantity of the inverter can be the duty cycle of any power switch tube in the inverter circuit or a modulation wave used to control the duty cycle of the power switch tube.

[0096] The bus voltage balancing control method of the present embodiment generates an adjusted control quantity through repeated control or dual closed-loop control of a voltage outer loop and a current inner loop based on an error adjustment value, an inductor current and an AC side voltage of an inverter, thereby eliminating the uncontrollability of the initial angle of the inductor current and the DC component in the modulation wave caused by the static adjustment error of the PI control on the AC adjustment quantity in the closed-loop control system, thereby achieving bus voltage balance and increasing dynamic response to better track the output steady state.

[0097] In some embodiments, a specific method for obtaining an error adjustment value based on the positive and negative bus pressure difference is also provided, and the method includes:

[0098] Based on the voltage difference between the positive bus voltage and the negative bus voltage, a DC component of the bus voltage difference is obtained, and the DC component of the bus voltage difference is the error adjustment value.

[0099] In this embodiment, the DC component of the bus voltage difference is input into the closed-loop control system of the inverter as an error adjustment value. An adjusted control quantity is generated based on the error adjustment value and the electrical parameters of the inverter. This can increase the control gain and thus enhance the bus voltage balancing effect, especially when the inverter is connected to an asymmetric load with positive and negative half waves.

[0100] In some other embodiments, a specific method for obtaining an error adjustment value based on a control amount of an inverter is also provided, and the method includes:

[0101] Based on the control quantity of the inverter, a DC component of the control quantity is obtained, and the DC component of the control quantity is the error adjustment value.

[0102] In this embodiment, the DC component of the control quantity is input into the closed-loop control system of the inverter as an error adjustment value. According to the error adjustment value and the electrical parameters of the inverter, an adjusted control quantity is generated. When the inverter is connected to various loads, especially inductive loads, it can respond quickly when switching loads to achieve bus voltage balance.

[0103] It should be noted that the steps shown in the above process or the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0104] The present application is described and illustrated below through specific embodiments. Figure 8 Schematic diagram of the structure of the inverter of some specific embodiments of the present application. Figure 8 As shown, the inverter includes an inverter circuit 71, a filter circuit 72 and a bus voltage balance control device 73. The inverter circuit 71 is used to invert direct current into alternating current, and includes two capacitors C1 and C2 connected in series and two power switches G1 and G2 connected in series. The filter circuit 72 is used to filter the alternating current output by the inverter circuit and provide it to the load. The filter circuit includes an inductor L and a capacitor C3. One end of the inductor L is connected to the connection midpoint between the capacitor C1 and the capacitor C2, and the other end is connected to one end of the capacitor C3. The other end of the capacitor C3 is connected to the connection midpoint between the power switch G1 and the power switch G2.

[0105] The bus voltage balancing control device 73 includes a compensation module 732 and a closed-loop control module 731. The compensation module 732 obtains an error adjustment value based on the voltage difference between the positive bus voltage and the negative bus voltage of the inverter and / or the control quantity of the inverter; the closed-loop control module 731 generates an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, controls the operation of the inverter according to the adjusted control quantity, and realizes bus voltage balance at the same time.

[0106] In this embodiment, the compensation module 732 includes a first compensation module, a second compensation module and a summing module. The first compensation module is used to obtain the DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage; the second compensation module is used to obtain the DC component of the control quantity based on the control quantity of the inverter; the summing module determines the error adjustment value based on the DC component of the bus voltage difference and the DC component of the control quantity.

[0107] The closed-loop control module 731 of this embodiment takes a dual closed-loop control module with a voltage outer loop and a current inner loop as an example, the control quantity takes the duty cycle of the power switch tube as an example, and the electrical parameter takes the inductor current i in the inverter as an example. L And the AC side voltage U inv This is an example, but not limited to this.

[0108] Specifically, the first compensation module includes:

[0109] The first summing unit, according to the positive bus voltage U busP With negative bus voltage U busN Get the difference ΔU between the two busP_N ;

[0110] Limiter, the difference between positive and negative bus voltages ΔU busP_N Perform limiting processing;

[0111] The first integration unit is used to calculate the difference between the positive and negative bus voltages ΔU busP_N Integrate to obtain the DC component u of the bus voltage difference bg ;

[0112] The average unit is used to obtain the inductor current i L The effective value of and normalize it;

[0113] A first multiplier is used to multiply the normalized effective value of the inductor current and the energy flow direction in the inverter to obtain a correction coefficient K;

[0114] The second multiplier converts the DC component u of the bus voltage difference bg Multiply it by the correction coefficient K to get the final corrected DC component K*u of the bus voltage difference bg .

[0115] The second compensation module includes:

[0116] The second integration unit integrates the duty cycle d of the power switch tube provided by the closed-loop control module 731 to obtain the DC component u of the duty cycle. rg .

[0117] The summation module is used to calculate the DC component K*u of the bus voltage difference bg and the DC component of the duty cycle u rgMake a difference and get the error adjustment value Δu g .

[0118] The closed-loop control module 731 includes:

[0119] The second summing unit converts the preset reference voltage U rms_ref The effective value of the AC voltage U rms Subtract and get the difference ΔU rms ;

[0120] The first PI control unit, the difference ΔU rms Perform proportional-integral control to obtain the AC side voltage reference value u ref ;

[0121] The third summing unit takes the AC side voltage reference value u ref and error adjustment value Δu g The sum of the AC side voltage u inv The instantaneous value of is subtracted to obtain the AC side voltage error value;

[0122] The second PI control unit performs proportional-integral control on the AC side voltage error value to obtain the output current reference value i ref ;

[0123] The fourth summing unit outputs the current reference value i ref The sampled inductor current i L Subtract to get the current error value;

[0124] The third PI control unit performs proportional control or proportional-integral control on the current error value to obtain the duty cycle d of the power switch tube.

[0125] The inverter further includes a driving module 74 for generating a driving signal for controlling the power switch tube G1 and the power switch tube G2 according to the duty cycle d.

[0126] In some embodiments, the compensation module may include only one of the first compensation module and the second compensation module. When the compensation module includes only the first compensation module, the DC component K*u of the final corrected bus voltage difference is bg As the error adjustment value; when the compensation module only includes the second compensation module, the DC component u of the duty cycle rg as the error adjustment value.

[0127] In some embodiments, the bus voltage balance control device is implemented using software control.

[0128] In some embodiments, the inverter further includes a controller, and the controller includes the bus voltage balancing control device.

[0129] This embodiment obtains the DC component of the positive and negative bus voltage difference and the DC component of the duty cycle, and inputs the difference between the two as an error adjustment value into the dual closed-loop control module to compensate for the AC side voltage reference value. The closed-loop control module obtains the adjusted duty cycle of the power switch tube according to the error adjustment value, the inductor current and the AC side voltage. The drive module generates a drive signal according to the duty cycle value to drive the power switch tube of the inverter circuit to turn on or off to achieve bus voltage balance. It can be unaffected by the control method of the voltage loop and the current loop in the dual closed-loop control system, and can feed back the output of the dual closed-loop control system in real time, improve the dynamic response of the dual closed-loop control system, and enhance the balancing effect of the bus midpoint when the inverter is connected to a positive and negative half-wave asymmetric load or an inductive load; this solution does not require the addition of hardware circuits, and can reduce the cost and loss of the system.

[0130] In some embodiments, the present application also provides a bus voltage balancing control device, which is used to implement the above embodiments and preferred implementations, and will not be repeated for what has been described. The terms "module", "unit", "subunit", etc. used below can be a combination of software and / or hardware that can implement a predetermined function.

[0131] In some embodiments, Fig. 9 is a structural block diagram of a bus voltage balancing control device in some embodiments of the present application, such as Fig. 9 As shown, the device comprises:

[0132] A compensation module 91, configured to obtain an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage of the inverter and / or a control variable of the inverter;

[0133] The closed-loop control module 93 is used to generate an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, control the inverter operation according to the adjusted control quantity, and achieve bus voltage balance at the same time.

[0134] The bus voltage balancing control device of this embodiment uses the positive and negative bus voltage differences and / or the inverter control quantity as two input variables of the compensation module through the compensation module 91, and obtains the error adjustment value according to at least one of the two input variables; generates the adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter through the closed-loop control module 93, controls the inverter operation according to the adjusted control quantity, and realizes bus voltage balance. It does not need to add hardware circuits, can reduce the cost and loss of the system, and is not affected by the control methods of the voltage loop and the current loop in the closed-loop control system. It has good dynamic performance and fast response speed, and at the same time ensures that the system can operate stably.

[0135] In some of the embodiments, the compensation module includes a first compensation module, a second compensation module and a summing module, the first compensation module is used to obtain the DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage; the second compensation module is used to obtain the DC component of the control quantity based on the control quantity of the inverter; the summing module is used to determine the error adjustment value based on the DC component of the bus voltage difference and the DC component of the control quantity.

[0136] The bus voltage balancing control device of this embodiment obtains the DC component of the bus voltage difference through the first compensation module, which can increase the control gain, thereby enhancing the bus voltage balancing effect, especially for the case where the inverter is connected to an asymmetric load with positive and negative half-waves; obtains the DC component of the control amount of the inverter through the second compensation module, and feeds back the output of the closed-loop control system in real time to improve the dynamic response of the closed-loop control system. When the inverter is connected to an inductive load, it can enhance the balancing effect of the bus midpoint, can quickly respond to the switching of various loads, improve the dynamic performance of the bus voltage balance and achieve rapid response.

[0137] In some of the embodiments, the electrical parameters of the inverter include the inductor current, and the first compensation module includes a first acquisition submodule and a second acquisition submodule, the first acquisition submodule is used to obtain the correction coefficient based on the inductor current; the second acquisition submodule is used to obtain the DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage, and the correction coefficient.

[0138] The bus voltage balancing control device of this embodiment uses the real-time inductor current to correct the amplitude of the DC component of the bus voltage difference through the first acquisition submodule; the DC component of the corrected bus voltage difference is obtained through the second acquisition submodule, thereby increasing the dynamic response while reducing the bus voltage deviation overshoot at low current, thereby improving the stability and effect of bus voltage balancing.

[0139] In some of the embodiments, the first compensation module further includes a limiter, which is used to limit the voltage difference between the positive bus voltage and the negative bus voltage, and obtain a DC component of the bus voltage difference according to the voltage difference after limiting.

[0140] The bus voltage balancing control device of this embodiment limits the voltage difference between the positive bus voltage and the negative bus voltage through a limiter, thereby protecting the closed-loop control system of the inverter and avoiding instability of the closed-loop control system due to an excessively large feedforward value when the voltage difference between the positive bus voltage and the negative bus voltage is too large (for example, when the voltage on the DC side capacitor is just established when the power is just turned on).

[0141] In some embodiments, the closed-loop control module is used to generate an adjusted control quantity through repeated control or dual closed-loop control of a voltage outer loop and a current inner loop based on the error adjustment value and the electrical parameters of the inverter. The electrical parameters of the inverter include the inductor current and the AC side voltage.

[0142] The bus voltage balancing control device of this embodiment generates an adjusted control quantity through a closed-loop control module, thereby eliminating the uncontrollability of the initial angle of the inductor current and the DC component in the modulation wave caused by the static adjustment error of the PI control on the AC adjustment quantity in the closed-loop control system, thereby achieving bus voltage balance, increasing dynamic response, and better tracking the output steady state.

[0143] In some embodiments, the compensation module only includes a first compensation module, which is used to obtain a DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage, and the DC component of the bus voltage difference is the error adjustment value.

[0144] The bus voltage balancing control device of this embodiment inputs the DC component of the bus voltage difference as an error adjustment value into the closed-loop control system of the inverter through the first compensation module, and generates an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, which can increase the control gain and thus enhance the bus voltage balancing effect, especially for the case where the inverter is connected to asymmetric loads with positive and negative half waves.

[0145] In some of the embodiments, the compensation module only includes a second compensation module, and the second compensation module is used to obtain a DC component of the control quantity based on the control quantity of the inverter, and the DC component of the control quantity is the error adjustment value.

[0146] The bus voltage balancing control device of this embodiment inputs the DC component of the control quantity as an error adjustment value into the closed-loop control system of the inverter through the second compensation module; generates an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, and can respond quickly when switching loads when the inverter is connected to various loads, especially inductive loads, to achieve bus voltage balance.

[0147] In some embodiments, the present application further provides an inverter, which includes an inverter circuit for inverting a DC bus voltage into an AC voltage, and the bus voltage balancing control device in the above embodiments.

[0148] The inverter of this embodiment inverts the DC voltage into AC voltage through an inverter circuit, and controls the bus voltage balance of the inverter through a bus voltage balance control device, thereby achieving bus voltage balance without changing the circuit structure, reducing the cost and loss of the system, and is not affected by the control method of the voltage loop and the current loop in the inverter closed-loop control system. It has good dynamic performance and fast response speed, and at the same time ensures that the system can operate stably.

[0149] In addition, in combination with the bus voltage balance control method provided in the above embodiments, a readable storage medium may be provided in this embodiment to implement the method. The readable storage medium stores a computer program; when the computer program is executed by a processor, any bus voltage balance control method in the above embodiments is implemented.

[0150] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementation modes, and will not be repeated in this embodiment.

[0151] It should be understood that the specific embodiments described herein are only used to explain the application, rather than to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of this application.

[0152] Obviously, the drawings are only some examples or embodiments of the present application. For ordinary technicians in the field, the present application can also be applied to other similar situations based on these drawings without creative work. In addition, it is understandable that although the work done in this development process may be complicated and lengthy, for ordinary technicians in the field, certain changes in design, manufacturing or production based on the technical content disclosed in this application are only conventional technical means and should not be regarded as insufficient content disclosed in this application.

[0153] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various locations in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0154] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. A bus voltage balance control method, the method is applied to an inverter, characterized in that: The method comprises: Obtaining an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage and / or a control variable of an inverter; Based on the error adjustment value and the electrical parameters of the inverter, an adjusted control amount is generated, and the inverter is controlled to operate according to the adjusted control amount to achieve bus voltage balance.

2. The method according to claim 1, characterized in that The obtaining of the error adjustment value based on the voltage difference between the positive bus voltage and the negative bus voltage and / or the control amount of the inverter comprises: Based on the voltage difference between the positive bus voltage and the negative bus voltage, obtaining a DC component of the bus voltage difference; Based on the control amount of the inverter, obtaining a DC component of the control amount; The error adjustment value is determined based on a DC component of the bus voltage difference and a DC component of the controlled variable.

3. The method according to claim 2, characterized in that The electrical parameters of the inverter include an inductor current, and obtaining a DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage includes: Obtaining a correction coefficient based on the inductor current and the flow direction of energy in the inverter; Based on the voltage difference between the positive bus voltage and the negative bus voltage and the correction coefficient, a DC component of the bus voltage difference is obtained.

4. The method according to claim 2, characterized in that: The obtaining of the DC component of the bus voltage difference based on the voltage difference between the positive bus voltage and the negative bus voltage comprises: A voltage difference between the positive bus voltage and the negative bus voltage is limited, and a DC component of the bus voltage difference is obtained according to the voltage difference after the limit.

5. The method according to claim 2, characterized in that: The control quantity of the inverter is the duty cycle of the power switch tube of the inverter or a modulation wave used to control the duty cycle of the power switch tube.

6. The method according to claim 1, characterized in that The electrical parameters of the inverter include an inductor current and an AC side voltage. The step of generating an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter includes: Based on the error adjustment value, the inductor current and the AC side voltage of the inverter, an adjusted control amount is generated through repeated control or double closed-loop control of a voltage outer loop and a current inner loop.

7. The method according to claim 1, characterized in that The obtaining of the error adjustment value based on the voltage difference between the positive bus voltage and the negative bus voltage and / or the control amount of the inverter comprises: Based on the voltage difference between the positive bus voltage and the negative bus voltage, a DC component of the bus voltage difference is obtained, where the DC component of the bus voltage difference is the error adjustment value; or Based on the control amount of the inverter, a DC component of the control amount is obtained, and the DC component of the control amount is the error adjustment value.

8. A bus voltage balance control device, the device is applied to an inverter, characterized in that: The device comprises: A compensation module, used for obtaining an error adjustment value based on a voltage difference between a positive bus voltage and a negative bus voltage and / or a control amount of an inverter; The closed-loop control module is used to generate an adjusted control quantity based on the error adjustment value and the electrical parameters of the inverter, and control the inverter to operate according to the adjusted control quantity to achieve bus voltage balance.

9. An inverter, characterized in that: The inverter comprises an inverter circuit for inverting a DC bus voltage into an AC voltage, and the bus voltage balancing control device as claimed in claim 8.

10. A readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, the steps of the bus voltage balancing control method according to any one of claims 1 to 7 are implemented.

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