DC voltage balance control method, device and converter

Abstract

The present invention relates to a method, device and converter for DC voltage balance control. The method for DC voltage balance control is used to control multiple series-connected converter units in a converter, and the method includes: obtaining the DC voltage value of each converter unit respectively; obtaining the minimum voltage value among multiple DC voltage values; generating corresponding control signals according to the DC voltage value and the minimum voltage value of each converter unit respectively, and the multiple control signals correspond to the multiple converter units one by one; transmitting each control signal to the corresponding converter unit respectively to balance the DC voltage value of each converter unit. By reasonably regulating the voltage value change in the converter unit, the problem of increased power consumption caused by uniformly paralleling resistors with fixed resistance values ​​in traditional technologies is avoided.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a method, a device and a converter for direct current voltage balance control. Background Art

[0002] At present, due to the limitation of the manufacturing level of power electronic devices, high-voltage converters generally adopt a topological structure of multiple modules in series. For example, static synchronous compensators use multiple full-bridge modules in series, modular multi-level converters use multiple half-bridge modules in series, and DC solid-state transformers use multiple dual-active modules in series. Considering the needs of modular production, as well as the requirements of electrical isolation and insulation withstand voltage, the control power supply of each module adopts high-potential energy extraction.

[0003] Generally speaking, the control power supply has a constant power characteristic. When the converter is in standby mode, it will affect the balance of the DC voltage. In order to achieve DC voltage balance, the parallel resistance method can be used. The voltage and current of the constant resistance load show positive characteristics, and the voltage and current of the constant power load show negative characteristics. The constant resistance load with positive characteristics is used to offset the constant power load with negative characteristics, thereby achieving DC voltage balance control. However, this method has a serious disadvantage of energy consumption. Summary of the invention

[0004] Based on this, it is necessary to provide a method, device and converter for DC voltage balance control with low energy consumption.

[0005] A method for controlling a DC voltage balance is provided, for controlling a plurality of series-connected converter units in a converter, the method comprising:

[0006] respectively obtaining a DC voltage value of each converter unit;

[0007] Obtaining a minimum voltage value among multiple DC voltage values;

[0008] Generate corresponding control signals according to the DC voltage value and the minimum voltage value of each commutation unit, and the multiple control signals correspond to the multiple commutation units one by one;

[0009] The control signals are transmitted to the corresponding converter units respectively to balance the DC voltage values ​​of the converter units.

[0010] In one embodiment, each commutation unit includes a variable resistor, and generates a corresponding control signal according to the DC voltage value and the minimum voltage value of each commutation unit, including:

[0011] respectively obtaining the voltage difference between each DC voltage value and the minimum voltage value;

[0012] Obtaining a preset balance coefficient, and obtaining a corresponding target duty cycle according to the voltage difference of each converter unit and the preset balance coefficient;

[0013] A control signal having a target duty cycle is generated, and the control signal is used to control the resistance value of the variable resistor.

[0014] In one embodiment, the variable resistor includes a power electronic switch and a power resistor, the resistance of the variable resistor is related to the on-off state of the power electronic switch, and obtaining the preset balance coefficient includes:

[0015] Obtaining a preset balance coefficient according to a preset proportional coefficient and a switching period of the power electronic switch respectively, wherein the preset proportional coefficient is determined according to at least one of a resistance value of the power resistor, a switching period of the power electronic switch, a DC capacitance value of the converter module, and a power of the power supply module;

[0016] Transmitting each control signal to each corresponding commutation unit respectively, including:

[0017] Each control signal is transmitted to the control end of each corresponding power electronic switch to control the on-off state of each power electronic switch.

[0018] In one embodiment, obtaining a corresponding target duty cycle according to the voltage difference of each converter unit and a preset balance coefficient includes:

[0019]

[0020] Where D is the target duty cycle, K is the preset proportional coefficient, Ts is the switching period of the power electronic switch, V i is the DC voltage value corresponding to the current commutation unit, V min is the minimum voltage, 0≤D≤1.

[0021] A DC voltage balance control device, comprising:

[0022] A voltage value acquisition module is used to respectively acquire the DC voltage value of each converter unit in the converter;

[0023] A minimum value acquisition module, used to obtain a minimum voltage value among multiple DC voltage values;

[0024] The control module is used to generate corresponding control signals according to the DC voltage value and the minimum voltage of each converter unit, and the multiple control signals correspond to the multiple converter units one by one; each control signal is transmitted to the corresponding converter unit to balance the DC voltage value of each converter unit.

[0025] A converter, comprising:

[0026] A plurality of commutation units, wherein the plurality of commutation units are connected in series, and each commutation unit has a corresponding DC voltage value;

[0027] Multiple variable resistors are respectively arranged in one-to-one correspondence with multiple commutation units, each variable resistor is respectively connected in parallel with the corresponding commutation unit, and the resistance of the variable resistor is configured to change according to the DC voltage value of the corresponding commutation unit to balance the DC voltage values ​​of the multiple commutation units.

[0028] In one embodiment, the variable resistor comprises:

[0029] A power resistor, one end of which is connected to one end of a corresponding current conversion unit;

[0030] A power electronic switch, one end of the power electronic switch is connected to the power resistor, the other end of the power electronic switch is connected to the other end of the corresponding converter unit, the control end of the power electronic switch is used to receive a control signal, and the power electronic switch is used to turn on and off under the control of the control signal to change the resistance value of the variable resistor.

[0031] In one embodiment, the power electronic switch includes a transistor and a diode;

[0032] The emitter of the transistor is connected to the anode of the diode, the base of the transistor is used to receive a control signal, and the collector of the transistor is connected to the cathode of the diode.

[0033] A converter system, comprising:

[0034] A power module, used for providing a power signal with constant power;

[0035] As the above-mentioned converter, the converter is connected to the power module;

[0036] The controller is connected to the converter and is used to respectively obtain the DC voltage value of each converter unit in the converter; obtain the minimum voltage value among multiple DC voltage values; generate corresponding control signals according to the DC voltage value of each converter unit and the minimum voltage value, and the multiple control signals correspond to the multiple converter units one by one; and transmit each control signal to the corresponding converter unit to balance the DC voltage value of each converter unit.

[0037] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0038] The above-mentioned DC voltage balance control method is used to control multiple series-connected converter units in a converter unit, and the method includes: obtaining the DC voltage value of each converter unit respectively; obtaining the minimum voltage value among multiple DC voltage values; generating corresponding control signals according to the DC voltage value and the minimum voltage value of each converter unit respectively, and multiple control signals correspond to multiple converter units one by one; transmitting each control signal to the corresponding converter unit respectively to balance the DC voltage value of each converter unit. In the traditional technology, in order to achieve the balance of DC voltage, a fixed resistor is connected in parallel in each converter unit. Although the balance of DC voltage can be achieved, the parallel resistor needs to exist in the circuit all the time, and in order to achieve a larger voltage balance, the power of the parallel resistor itself is also large, which will lead to an increase in power consumption. The present invention tracks the lowest voltage value in multiple converter units, obtains control signals according to the current voltage value in each converter unit, and reasonably adjusts the change of the voltage value in each converter unit with different control signals to balance the DC voltage value of each converter unit, avoiding the problem of large power consumption caused by the uniform parallel connection of fixed resistance value resistors in the traditional technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 This is a flow chart of a method for controlling a DC voltage balance in one embodiment;

[0041] Figure 2 The second flowchart of the method for DC voltage balance control in one embodiment;

[0042] Figure 3 The third flowchart of the method for DC voltage balance control in one embodiment;

[0043] Figure 4 A diagram showing a DC voltage balance control result in an embodiment;

[0044] Figure 5 2 is a schematic diagram of the structure of a DC voltage balance control device in an embodiment;

[0045] Figure 6 is a schematic structural diagram of a converter in one embodiment;

[0046] Figure 7 FIG. 1 is a schematic structural diagram of a converter system in an embodiment. DETAILED DESCRIPTION

[0047] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0049] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0050] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0051] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0052] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0053] In one embodiment, if Figure 1 As shown, a method for DC voltage balance control is provided, which is used to control multiple series-connected converter units in a converter unit. The method for DC voltage balance control includes steps S100 to S400.

[0054] Step S100, respectively obtaining the DC voltage value of each converter unit.

[0055] Step S200, obtaining a minimum voltage value among a plurality of DC voltage values.

[0056] Specifically, in this embodiment, the DC voltage value of each converter unit is obtained at the same time, and multiple DC voltage values ​​are aggregated into a DC voltage set, and the minimum voltage value in the DC voltage set is found through an algorithm. For example, when there are n converter units in this embodiment, n DC voltage values ​​are first obtained, and a DC voltage set containing n DC voltage values ​​is formed, and the minimum value in the DC voltage set is found through an algorithm:

[0057] V min =min{V 1 , V 2 , V 3 ,......V i ,......V n}

[0058] Among them, V min is the minimum voltage, V 1 , V 2 , V 3 ,......V i ,......V n are respectively the DC voltage values ​​of each converter unit obtained.

[0059] Step S300, generating corresponding control signals according to the DC voltage value and the minimum voltage value of each commutation unit, wherein the plurality of control signals correspond to the plurality of commutation units one by one.

[0060] Among them, each converter unit can be individually configured with a corresponding control module, and the control module can be connected to the minimum value acquisition module for obtaining the minimum voltage value and the voltage value acquisition module for obtaining the DC voltage value. The minimum value acquisition module can send the minimum voltage value to the control module of each converter unit. The control module is used to receive the minimum voltage value and the DC voltage value of each converter unit, and generate corresponding control signals according to the DC voltage value and the minimum voltage value of each converter unit to balance the voltage value in the converter unit.

[0061] Step S400: transmitting each control signal to each corresponding converter unit respectively to balance the DC voltage value of each converter unit.

[0062] In this embodiment, the DC voltage values ​​in multiple converter units are obtained, and control signals are reasonably allocated to each converter unit to achieve the purpose of balancing the DC voltage. At the same time, the control signal in this embodiment is generated based on the actual DC voltage of each current converter unit. Therefore, it can avoid the problem of high power consumption caused by connecting resistors with only one resistance value in parallel in traditional technology.

[0063] In one embodiment, each of the above-mentioned commutation units includes a variable resistor, such as Figure 2 As shown, a method for DC voltage balance control is provided, in which step S300 includes steps S310 to S330.

[0064] Step S310, respectively obtaining the voltage difference between each DC voltage value and the minimum voltage value.

[0065] Specifically, in this embodiment, the DC voltage value in each converter unit can be continuously obtained according to a preset time interval before the DC voltage balance is reached, and the minimum voltage value is obtained according to each DC voltage value obtained at the current time point, and then the voltage difference between each DC voltage value and the minimum voltage value is obtained respectively. The voltage value in each converter unit is monitored in real time to achieve real-time tracking of the minimum DC voltage value.

[0066] The preset interval can be reasonably set according to the voltage difference in each converter unit. For example, if the DC voltage difference of each converter unit is small, a larger time interval can be set to achieve voltage balance in a shorter time. If the DC voltage difference of each converter unit is large, a smaller time interval can be set to achieve the purpose of real-time tracking of the minimum voltage before the DC voltage is balanced.

[0067] Step S320, obtaining a preset balance coefficient, and obtaining a corresponding target duty cycle according to the voltage difference of each converter unit and the preset balance coefficient.

[0068] Among them, the duty cycle refers to the proportion of the power-on time to the total time in a pulse cycle. For example: the duty cycle of a pulse sequence with a pulse width of 1μs and a signal period of 4μs is 0.25. By adjusting the target duty cycle, the current value flowing through the variable resistor can be changed, that is, the resistance value of the variable resistor is adjusted. Among them, the smaller the duty cycle, the larger the resistance value. When the duty cycle is 0, the resistance value is infinite; the smaller the duty cycle, the smaller the resistance value. When the duty cycle is 1, the resistance value is the smallest.

[0069] Step S330 , generating a control signal with a target duty cycle, wherein the control signal is used to control the resistance value of the variable resistor.

[0070] Among them, it can be understood that the energy consumption can be adjusted by controlling the change in the resistance of the variable resistor. For example, if the current DC voltage value of the converter unit is equal to the obtained minimum voltage value, that is, the voltage difference between the DC voltage value and the minimum voltage value is 0, then the corresponding target duty cycle obtained according to the voltage difference of each converter unit and the preset balance coefficient is also 0, that is, the resistance value in the variable resistor is infinite, which is equivalent to a circuit break, and no electric energy is consumed. By analogy, if the current DC voltage value of the converter unit is much larger than the obtained minimum voltage value, and is the maximum value of the obtained DC voltage value, the target duty cycle is approximately equal to 1, the resistance value in the variable resistor is the smallest, and the electric energy consumption is the largest. However, if the current DC voltage value of the converter unit is between the maximum value of the obtained DC voltage value and the minimum voltage value, the target duty cycle is between 0 and 1. At this time, the energy consumption of the converter unit is also between the minimum energy consumption and the maximum energy consumption.

[0071] In one embodiment, the variable resistor includes a power electronic switch and a power resistor, and the resistance of the variable resistor is related to the on-off state of the power electronic switch, such as Figure 3 As shown, a method for DC voltage balance control is provided, wherein step S320 of the method includes step S321 and step S322.

[0072] Step S321, obtaining a preset balance coefficient according to a preset proportional coefficient and a switching period of the power electronic switch, wherein the preset proportional coefficient is determined according to at least one of the resistance value of the power resistor, the switching period of the power electronic switch, the DC capacitance value of the converter module and the power of the power supply module.

[0073] The preset proportionality coefficient is mainly related to the power value of the constant power source input to the commutation unit, the resistance value of the power resistor, the power electronic switching frequency, etc.

[0074] Step S322, obtaining the corresponding target duty cycle according to the voltage difference of each converter unit and the preset balance coefficient.

[0075] Among them, the target duty cycle in this embodiment determines the on-off state of the electronic switch. For example, if the duty cycle is 0.5, then within a power electronic switch cycle, the on-time and off-time of the electronic switch are equal. At this time, the resistance value is greater than the power resistance, and the energy consumption is also between the minimum energy consumption and the maximum energy consumption.

[0076] Step S400 includes step S410.

[0077] Step S410: transmitting each control signal to the control terminal of each corresponding power electronic switch to control the on-off state of each power electronic switch to balance the DC voltage value of each converter unit.

[0078] Specifically, the power electronic switch is a fully controlled power electronic switch, wherein the fully controlled power electronic switch is a power electronic device that can be controlled to be turned on and off by a control signal. The fully controlled power electronic switch has the function of flexibly adjusting the on and off time of the switch within a fixed time period.

[0079] In this embodiment, the on-off state of the variable resistor is regulated according to the duty cycle by the power electronic switch to change the resistance value, thereby improving the flexibility of the variable resistor.

[0080] In one embodiment, in the DC voltage balance control method, step S322 includes:

[0081]

[0082] Where D is the target duty cycle, K is the preset proportional coefficient, Ts is the switching period of the power electronic switch, V i is the DC voltage value corresponding to the current commutation unit, V min is the minimum voltage, 0≤D≤1.

[0083] Specifically, the power electronic switch in this embodiment may be a fully controlled power electronic switch, which has a stable switching cycle and is easy to calculate.

[0084] In one embodiment, continue to see Figure 3 , provides a method for direct current voltage balance control, the method comprising:

[0085] Step S100, respectively obtaining the DC voltage value of each converter unit.

[0086] Step S200, obtaining a minimum voltage value among a plurality of DC voltage values.

[0087] Step S310, respectively obtaining the voltage difference between each DC voltage value and the minimum voltage value.

[0088] Step S321, obtaining a preset balance coefficient according to a preset proportional coefficient and a switching period of the power electronic switch.

[0089] Step S322, obtaining the corresponding target duty cycle according to the voltage difference of each converter unit and the preset balance coefficient, wherein the duty cycle can be obtained according to the following formula:

[0090]

[0091] Where D is the target duty cycle, K is the preset proportional coefficient, Ts is the switching period of the power electronic switch, V i is the DC voltage value corresponding to the current commutation unit, V min is the minimum voltage, 0≤D≤1.

[0092] Step S330 , generating a control signal with a target duty cycle, wherein the control signal is used to control the resistance value of the variable resistor.

[0093] Step S410: transmitting each control signal to the control terminal of each corresponding power electronic switch to control the on-off state of each power electronic switch to balance the DC voltage value of each converter unit.

[0094] Specifically, Figure 4 As shown, it is the DC voltage state of three dual-active full-bridge units connected in series. The horizontal axis represents time, and the vertical axis represents voltage value. It can be seen that the DC voltage is not balanced, V12>V13>V11. At t0, the method of DC voltage balance control of this embodiment is used. Since the DC voltage of the dual-active full-bridge unit corresponding to V12 is the highest, the power electronic switch S02 is fully turned on, the DC voltage is reduced, and the DC voltage of the dual-active full-bridge unit corresponding to V11 begins to increase. At t1, the DC voltage imbalance of the three dual-active full-bridge units is reduced, and the power electronic switch S02 is periodically turned on and off. At t2, the DC voltage of the three dual-active full-bridge units is balanced, and the conduction time of S02 is reduced. Finally, the balanced control of the DC voltage of the three dual-active full-bridge units is achieved.

[0095] The specific explanation of each step in this embodiment is consistent with the above content and will not be repeated here. By tracking the minimum voltage, while achieving the purpose of balancing the DC voltage, the power consumption problem caused by only connecting one resistor in parallel in the traditional technology can be avoided.

[0096] In one embodiment, if Figure 5 As shown, a DC voltage balance control device 100 is provided, and the DC voltage balance control device 100 includes: a voltage value acquisition module 110, a minimum value acquisition module 120 and a control module 130. The voltage value acquisition module 110 is used to respectively acquire the DC voltage value of each converter unit in the converter; the minimum value acquisition module 120 is used to acquire the minimum voltage value among multiple DC voltage values; the control module 130 is used to generate corresponding control signals according to the DC voltage value and the minimum voltage value of each converter unit, and the multiple control signals correspond to the multiple converter units one by one; and each control signal is transmitted to the corresponding converter units to balance the DC voltage value of each converter unit.

[0097] In one embodiment, if Figure 6 As shown, a converter 200 is provided, the converter 200 includes a plurality of converter units 210. Figure 6For example, the "plurality" in this embodiment may be "two". A plurality of converter units 210 are connected in series, and each converter unit 210 has a corresponding DC voltage value; a plurality of variable resistors 220 are respectively arranged in one-to-one correspondence with the plurality of converter units 210, and each variable resistor 220 is respectively connected in parallel with the corresponding converter unit 210, and the resistance of the variable resistor 220 is configured to change according to the DC voltage value of the corresponding converter unit 210 to balance the DC voltage values ​​of the plurality of converter units 210.

[0098] In one embodiment, continue to see Figure 6 Taking one of the variable resistors 220 as an example, the variable resistor 220 includes: a power resistor 221 and a power electronic switch 222. One end of the power resistor 221 is connected to one end of the corresponding commutation unit 210; one end of the power electronic switch 222 is connected to the power resistor 221, and the other end of the power electronic switch 222 is connected to the other end of the corresponding commutation unit 210. The control end of the power electronic switch 222 is used to receive a control signal, and the power electronic switch 222 is used to turn on and off under the control of the control signal to change the resistance value of the variable resistor.

[0099] Among them, the resistance value of the power resistor 221 is much larger than the resistance value of the resistor connected in parallel in each converter unit in the traditional technology, but the resistance value of the power resistor 221 is not infinite and cannot be conducted. The resistance value of the power resistor 221 can be set according to the actual application scenario.

[0100] In one embodiment, continue to see Figure 6 Taking one of the power electronic switches 222 as an example, the power electronic switch 222 includes a transistor and a diode; wherein the emitter of the transistor is connected to the anode of the diode, the base of the transistor is used to receive a control signal, and the collector of the transistor is connected to the cathode of the diode.

[0101] Specifically, the converter 200, taking the power electronic switch 222 included in this embodiment as an example, includes a first end and a second end. The first end of the converter 200 is connected to the collector of the transistor in the power electronic switch 222 in this embodiment, and the first end of the converter 200 is connected to the emitter of the collector of the transistor in the power electronic switch 222 in this embodiment.

[0102] In one embodiment, if Figure 7As shown, a converter system 300 is provided, comprising: a power module 310, a converter 200 as described above, and a controller 320. The power module 310 is used to provide a power signal with constant power; the converter 200 is connected to the power module 310; the controller 320 is connected to the converter 200, and is used to respectively obtain the DC voltage value of each converter unit in the converter; obtain the minimum voltage value among multiple DC voltage values; generate corresponding control signals according to the DC voltage value and the minimum voltage value of each converter unit, and the multiple control signals correspond to the multiple converter units one by one; and transmit each control signal to the corresponding converter unit to balance the DC voltage value of each converter unit.

[0103] Specifically, the positive electrode and the negative electrode of the power module 310 are respectively connected to the two ends of the converter 200. Figure 7 For example, the positive and negative electrodes of the power module 310 in this embodiment may be connected to the first end and the second end of the converter 200 in the above embodiment, respectively.

[0104] The system in this embodiment reasonably regulates the voltage value in each converter unit, thereby avoiding the problem of increased power consumption caused by uniformly connecting resistors with fixed resistance values ​​in parallel in the traditional technology.

[0105] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned DC voltage balance control method when executing the computer program.

[0106] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, each step of the above-mentioned direct current voltage balance control method is implemented.

[0107] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0108] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for DC voltage balance control, It is characterized in that The method is used to control a plurality of series-connected commutation units in a commutation device, and comprises: The DC voltage value of each of the commutation units is obtained respectively; each of the commutation units comprises a variable resistor; the variable resistor comprises a power electronic switch and a power resistor; the resistance value of the variable resistor is related to the on-off state of the power electronic switch; Obtaining a minimum voltage value among the plurality of DC voltage values; Generate corresponding control signals according to the DC voltage value of each of the commutation units and the minimum voltage value, respectively, wherein the plurality of control signals correspond one-to-one to the plurality of commutation units respectively; Transmitting each of the control signals to the corresponding commutation units respectively to balance the DC voltage values ​​of each of the commutation units; Wherein, the generating of the corresponding control signal according to the DC voltage value of each of the commutation units and the voltage minimum value respectively comprises: respectively obtaining the voltage difference between each of the DC voltage values ​​and the voltage minimum value; obtaining a preset balance coefficient, respectively obtaining the corresponding target duty cycle according to the voltage difference of each of the commutation units and the preset balance coefficient; generating the control signal having the target duty cycle, wherein the control signal is used to control the resistance value of the variable resistor; The obtaining of the preset balance coefficient comprises: obtaining the preset balance coefficient according to a preset proportional coefficient and a switching cycle of the power electronic switch respectively, wherein the preset proportional coefficient is determined according to at least one of the resistance value of the power resistor, the switching cycle of the power electronic switch, the DC capacitance value of the commutation unit, and the power of the power module; The respectively transmitting each of the control signals to the corresponding each of the commutation units comprises: respectively transmitting each of the control signals to the control ends of the corresponding each of the power electronic switches to control the on-off state of each of the power electronic switches.

2. The method according to claim 1, It is characterized in that The obtaining corresponding target duty ratios according to the voltage difference of each of the commutation units and the preset balance coefficients respectively includes: in, is the target duty cycle, is the preset proportionality coefficient, is the switching period of the power electronic switch, is the DC voltage value corresponding to the current commutation unit, is the minimum voltage, .

3. A DC voltage balance control device, It is characterized in that include: A voltage value acquisition module is used to respectively acquire the DC voltage value of each converter unit in the converter; Each of the commutation units comprises a variable resistor; The variable resistor includes a power electronic switch and a power resistor; the resistance value of the variable resistor is related to the on-off state of the power electronic switch; A minimum value acquisition module, used to obtain a minimum voltage value among multiple DC voltage values; A control module, used for generating corresponding control signals according to the DC voltage value of each of the commutation units and the minimum voltage value, wherein the plurality of control signals correspond to the plurality of commutation units one by one; Transmitting each of the control signals to the corresponding commutation units respectively to balance the DC voltage values ​​of each of the commutation units; Wherein, the generating of the corresponding control signal according to the DC voltage value of each of the commutation units and the voltage minimum value respectively comprises: respectively obtaining the voltage difference between each of the DC voltage values ​​and the voltage minimum value; obtaining a preset balance coefficient, respectively obtaining the corresponding target duty cycle according to the voltage difference of each of the commutation units and the preset balance coefficient; generating the control signal having the target duty cycle, wherein the control signal is used to control the resistance value of the variable resistor; The obtaining of the preset balance coefficient comprises: obtaining the preset balance coefficient according to a preset proportional coefficient and a switching cycle of the power electronic switch respectively, wherein the preset proportional coefficient is determined according to at least one of the resistance value of the power resistor, the switching cycle of the power electronic switch, the DC capacitance value of the commutation unit, and the power of the power module; The respectively transmitting each of the control signals to the corresponding each of the commutation units comprises: respectively transmitting each of the control signals to the control ends of the corresponding each of the power electronic switches to control the on-off state of each of the power electronic switches.

4. An inverter system, It is characterized in that include: A power module, used for providing a power signal with constant power; A converter, the converter being connected to the power module; A controller connected to the converter, and configured to respectively obtain a DC voltage value of each converter unit in the converter; and obtain a minimum voltage value among a plurality of DC voltage values; Generate corresponding control signals according to the DC voltage value of each of the commutation units and the minimum voltage value, respectively, wherein the plurality of control signals correspond one-to-one to the plurality of commutation units respectively; Transmitting each of the control signals to the corresponding commutation units respectively to balance the DC voltage values ​​of each of the commutation units; Each of the commutation units comprises a variable resistor; the variable resistor comprises a power electronic switch and a power resistor; the resistance value of the variable resistor is related to the on-off state of the power electronic switch; Wherein, the generating of the corresponding control signal according to the DC voltage value of each of the commutation units and the voltage minimum value respectively comprises: respectively obtaining the voltage difference between each of the DC voltage values ​​and the voltage minimum value; obtaining a preset balance coefficient, respectively obtaining the corresponding target duty cycle according to the voltage difference of each of the commutation units and the preset balance coefficient; generating the control signal having the target duty cycle, wherein the control signal is used to control the resistance value of the variable resistor; The obtaining of the preset balance coefficient comprises: obtaining the preset balance coefficient according to a preset proportional coefficient and a switching cycle of the power electronic switch respectively, wherein the preset proportional coefficient is determined according to at least one of the resistance value of the power resistor, the switching cycle of the power electronic switch, the DC capacitance value of the commutation unit, and the power of the power module; The respectively transmitting each of the control signals to the corresponding each of the commutation units comprises: respectively transmitting each of the control signals to the control ends of the corresponding each of the power electronic switches to control the on-off state of each of the power electronic switches.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, It is characterized in that When the processor executes the computer program, the steps of the method according to any one of claims 1 to 2 are implemented.

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