Control circuit and device for bus capacitor ripple current in a common dc bus converter

Abstract

The embodiment of the application discloses a control circuit and equipment for bus capacitor ripple current in a common DC bus converter, comprising: a first converter and a second converter are connected to the same DC bus, a carrier signal generation unit output end is connected with a first converter control unit input end and a second converter control unit input end respectively, a first converter control unit output end is connected with the first converter, and a second converter control unit output end is connected with the second converter; the carrier signal generation unit generates a target carrier signal according to a DC bus voltage signal or a DC bus capacitor current signal and a reference carrier signal; the first converter control unit generates a first control signal according to a first voltage signal, a first current signal, a DC bus voltage signal and a first carrier signal; and the second converter control unit generates a second control signal according to a second voltage signal, a second current signal and a second carrier signal.

Description

Technical Field

[0001] This application relates to the field of power conversion technology, and in particular to a control circuit and device for bus capacitor ripple current in a common DC bus converter. Background Technology

[0002] In fields such as uninterruptible power supplies (UPS) and frequency converters, the circuit topology of a three-phase common DC bus converter contains a common DC bus. This common DC bus will bear a large high-frequency ripple current. Under normal circumstances, this high-frequency ripple current is absorbed by the DC bus capacitor. However, because the DC bus capacitor bears a large high-frequency ripple current for a long time, the capacitor loss is high, the temperature is high, and the capacitor life is affected. Therefore, controlling the high-frequency ripple current on the DC bus is crucial for the converter. Related technologies refer to [reference needed] for controlling the high-frequency ripple current on the common DC bus. Figure 1 As shown, high-frequency ripple current on the common DC bus is suppressed by connecting an inductor in series with the common DC bus. However, this method has the problem of increased cost. Summary of the Invention

[0003] This application aims to provide a control circuit and device for the bus capacitor ripple current in a common DC bus converter, in order to solve the problems of high capacitor loss, low efficiency and low lifespan.

[0004] The technical solution of this application is implemented as follows:

[0005] In a first aspect, a control circuit for bus capacitor ripple current in a common DC bus converter is provided. The control circuit includes: a carrier signal generation unit, a first converter control unit, a second converter control unit, a first converter, and a second converter, wherein the first converter and the second converter are connected to the same DC bus.

[0006] The output terminal of the carrier signal generation unit is connected to the input terminal of the first converter control unit and the input terminal of the second converter control unit, respectively. The output terminal of the first converter control unit is connected to the first converter, and the output terminal of the second converter control unit is connected to the second converter.

[0007] The carrier signal generation unit generates a target carrier signal based on the DC bus voltage signal or DC bus capacitor current signal and a reference carrier signal.

[0008] The first converter control unit generates a first control signal for switching control of a switching tube in the first converter according to a first voltage signal of a three-phase alternating current voltage of the first converter, a first current signal of a three-phase current, the DC bus voltage signal, and a first carrier signal in the target carrier signal;

[0009] The second converter control unit generates a second control signal for switching control of a switching tube in the second converter according to a second voltage signal of a three-phase alternating current voltage of the second converter, a second current signal of a three-phase current, and a second carrier signal in the target carrier signal.

[0010] In a second aspect, a device is provided, and the device comprises the bus capacitor ripple current control circuit in the common DC bus converter.

[0011] The bus capacitor ripple current control circuit and the device in the common DC bus converter provided by the embodiments of the present application, the control circuit comprises: a carrier signal generation unit, a first converter control unit, a second converter control unit, a first converter, and a second converter, the first converter and the second converter are connected to the same DC bus, wherein the output end of the carrier signal generation unit is connected to the input end of the first converter control unit and the input end of the second converter control unit respectively, the output end of the first converter control unit is connected to the first converter, and the output end of the second converter control unit is connected to the second converter; wherein the carrier signal generation unit generates a target carrier signal according to a DC bus voltage signal or a DC bus capacitor current signal of the DC bus and a reference carrier signal; the first converter control unit generates a first control signal for switching control of a switching tube in the first converter according to a first voltage signal of a three-phase alternating current voltage of the first converter, a first current signal of a three-phase current, a DC bus voltage signal, and a first carrier signal in the target carrier signal; and the second converter control unit generates a second control signal for switching control of a switching tube in the second converter according to a second voltage signal of a three-phase alternating current voltage of the second converter, a second current signal of a three-phase current, and a second carrier signal in the target carrier signal.

[0012] That is, without increasing the hardware, the application generates a plurality of control signals based on the target carrier signal obtained by the carrier signal generation unit according to the direct current bus voltage signal or the direct current bus capacitor current signal obtained at the current time and the reference carrier signal, so that the at least two converters work cooperatively, thereby reducing the common direct current bus capacitor ripple current of the at least two converters, reducing the self loss of the direct current bus capacitor, improving the life of the capacitor, ensuring the reliability of the system, and improving the efficiency of the converter; at the same time, due to the reduction of the direct current bus capacitor current ripple, more parallel capacitors are not needed to meet the normal and reliable operation of the converter, thereby reducing the cost of the capacitor itself, and further, fewer parallel capacitors are used to ensure the current resistance, thereby effectively reducing the volume of the bus capacitor. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A circuit structure schematic diagram of parallel multiple inductors in the related art;

[0014] Figure 2 A circuit topology structure schematic diagram of a common direct current bus converter provided by an embodiment of the application;

[0015] Figure 3 Another circuit topology structure schematic diagram of a common direct current bus converter provided by an embodiment of the application;

[0016] Figure 4 Still another circuit topology structure schematic diagram of a common direct current bus converter provided by an embodiment of the application;

[0017] Figure 5 Still another circuit topology structure schematic diagram of a common direct current bus converter provided by an embodiment of the application;

[0018] Figure 6 A structure schematic diagram of a control circuit of a bus capacitor ripple current in a common direct current bus converter provided by an embodiment of the application;

[0019] Figure 7 Another structure schematic diagram of a control circuit of a bus capacitor ripple current in a common direct current bus converter provided by an embodiment of the application;

[0020] Figure 8 A result schematic diagram of a phase shift angle and a direct current bus capacitor current under different power factors provided by an embodiment of the application;

[0021] Figure 9 Still another structure schematic diagram of a control circuit of a bus capacitor ripple current in a common direct current bus converter provided by an embodiment of the application;

[0022] Figure 10A structure diagram of a control circuit of a bus capacitor ripple current in a common DC bus converter is provided for another embodiment of the present application;

[0023] Figure 11 A structure diagram of another control circuit of a bus capacitor ripple current in a common DC bus converter is provided for another embodiment of the present application;

[0024] Figure 12 A structure diagram of another carrier signal generation unit is provided for an embodiment of the present application;

[0025] Figure 13 A structure diagram of another carrier signal generation unit is provided for an embodiment of the present application;

[0026] Figure 14 A structure diagram of a device is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the personnel in the technical field better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the personnel in the technical field without creative labor fall within the scope of protection of the present application.

[0028] The terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish different objects, and are not used to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include other steps or units not listed or can optionally include other steps or units inherent to the process, method, product or device.

[0029] In this document, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor is it independent or alternative to other embodiments. The skilled person in the art explicitly and implicitly understands that the embodiments described herein can be combined with other embodiments.

[0030] In order to better understand the purpose, structure and function of the present application, before the control circuit of the common DC bus capacitor ripple current provided by the present application is described, the related art is first explained and described.

[0031] In the field of UPS and frequency converter, there is a common DC bus in the circuit topology of three-phase common DC bus converter, which will bear a large high-frequency ripple current. In general, the high-frequency ripple current will be absorbed by the common DC bus capacitor, but due to the long time of the common DC bus capacitor bearing a large high-frequency ripple current, the capacitor will be damaged and the temperature will be high, which will affect the service life of the capacitor. Therefore, controlling the high-frequency ripple current of the common DC bus capacitor is crucial to the converter.

[0032] In the related art, in order to control the high-frequency ripple current on the common DC bus capacitor, the following three ways are used. Way one, as shown in Figure 1 , Figure 1 It shows a circuit structure diagram of the related art of series connection of multiple inductors, which suppresses the high-frequency ripple current on the common DC bus by connecting inductors in series in the common DC bus. Way two, there are two inverters in the converter, by changing the switching sequence of the two inverters, the two bus currents respectively show low, medium and high, and high, medium and low, so that the total ripple current of the two DC bus currents after superposition is reduced. Way three, the carrier of the modulation wave of the two inverters is set to a fixed phase shift angle such as 90 degrees or 0 degrees to suppress the ripple current on the common DC bus. However, the above way one introduces inductors, which at least has the problem of increasing cost, and the ways two and three change the switching sequence of the inverter or take a fixed phase shift angle, which may cause the ripple current to increase due to the influence of power factor, and increase power consumption.

[0033] In view of Figures 2 to 5 It shows four different circuit topology structure diagrams of common DC bus converters provided by the embodiments of the application. The embodiments of the application provide a control circuit for bus capacitor ripple current in a common DC bus converter, which is used to control the circuit topology structure of a three-phase common DC bus converter. Of course, the circuit topology structure of the three-phase common DC bus converter includes but is not limited to the three-phase H-bridge converter topology, and can also be used for three-phase diode neutral point clamped (DNPC), three-phase ANPC, etc.

[0034] Referring to Figure 6 , Figure 6 It shows a structure diagram of a control circuit for bus capacitor ripple current in a common DC bus converter provided by the embodiments of the application. The control circuit for bus capacitor ripple current in the common DC bus converter 100 includes:

[0035] The carrier signal generating unit 10, the first converter control unit 20, the second converter control unit 30, the first converter 40 and the second converter 50 are connected to the same DC bus (not shown in the figure), wherein,

[0036] The output end of the carrier signal generating unit 10 is connected to the input end of the first converter control unit 20 and the input end of the second converter control unit 30 respectively, the output end of the first converter control unit 20 is connected to the first converter 40, and the output end of the second converter control unit 30 is connected to the second converter 50;

[0037] The carrier signal generating unit 10 generates a target carrier signal according to a DC bus voltage signal or a DC bus capacitor current signal of the DC bus and a reference carrier signal;

[0038] The first converter control unit 20 generates a first control signal for switching control of a switching tube in the first converter 40 according to a first voltage signal of three-phase alternating current voltage of the first converter 40, a first current signal of three-phase current, a DC bus voltage signal and a first carrier signal in the target carrier signal;

[0039] The second converter control unit 30 generates a second control signal for switching control of a switching tube in the second converter 50 according to a second voltage signal of three-phase alternating current voltage of the second converter 50, a second current signal of three-phase current and a second carrier signal in the target carrier signal.

[0040] In the embodiment of the application, the DC bus voltage signal V dc , the DC bus capacitor current signal i dc , the first voltage signal V 1ABC of three-phase alternating current voltage of the first converter 40 and the first current signal V 1ABC of three-phase current, and the second voltage signal V 2ABC of three-phase alternating current voltage of the second converter 50 and the second current signal i 2ABC of three-phase current in the control circuit can be directly collected by a collection unit or obtained by calculation. Here, the collection unit includes but is not limited to various devices capable of collecting signals such as a voltmeter and a current meter.

[0041] In the embodiment of the application, the target carrier signal includes at least two carrier signals, and the two carrier signals can be the same or different. It should be noted that the target carrier signal includes a reference carrier signal, and of course, the target carrier signal can not include the reference carrier signal. Here, the reference carrier signal C o may be a triangular wave, and the reference carrier signal C o may also be a sawtooth wave.

[0042] As can be seen from the above, without increasing hardware, the application generates a plurality of control signals based on the target carrier signal obtained by the carrier signal generation unit according to the direct current bus voltage signal or the direct current bus capacitor current signal obtained at the current time and the reference carrier signal, so that at least two converters work cooperatively, thereby reducing the common direct current bus capacitor ripple current of the at least two converters, reducing the self loss of the direct current bus capacitor, improving the life of the capacitor, ensuring the reliability of the system, and improving the efficiency of the converter; at the same time, due to the reduction of the direct current bus capacitor current ripple, fewer capacitors in parallel can meet the normal and reliable operation of the converter, thereby reducing the cost of the capacitor itself, and further, fewer capacitors in parallel are used to ensure the current resistance, thereby effectively reducing the volume of the bus capacitor.

[0043] In some embodiments, referring to Figure 7 , it is shown that the structure schematic diagram of the control circuit of the bus capacitor ripple current in the common direct current bus converter provided by the embodiment of the application, the first converter control unit 20 includes: a first modulation signal generation unit 201 and a first modulation unit 202, wherein, Figure 7 It is shown that the structure schematic diagram of the control circuit of the bus capacitor ripple current in the common direct current bus converter provided by the embodiment of the application, the first converter control unit 20 includes: a first modulation signal generation unit 201 and a first modulation unit 202, wherein,

[0044] The output end of the first modulation signal generation unit 201 is connected with the input end of the first modulation unit 202, and the output end of the first modulation unit 202 is connected with the first converter 40;

[0045] Wherein, the first modulation signal generation unit 201 generates the first modulation signal according to the first voltage signal, the first current signal and the direct current bus voltage signal, and the first modulation unit 202 generates the first control signal according to the first modulation signal and the first carrier signal;

[0046] The second converter control unit 30 includes: a second modulation signal generation unit 301 and a second modulation unit 302, wherein, the output end of the second modulation signal generation unit 301 is connected with the input end of the second modulation unit 302, and the output end of the second modulation unit 302 is connected with the second converter 50;

[0047] Wherein, the second modulation signal generation unit 301 generates the second modulation signal according to the second voltage signal and the second current signal, and one of the direct current bus voltage signal or the speed or position of the motor rotor, and the second modulation unit 302 generates the second control signal according to the second modulation signal and the second carrier signal;

[0048] The carrier signal generation unit 10 includes: a phase shift angle processing unit 101 and a carrier processing unit 102, wherein,

[0049] An output terminal of the phase-shifting angle processing unit 101 is connected with an input terminal of the carrier processing unit 102, a first output terminal of the carrier processing unit 102 is connected with an input terminal of the first modulation unit 202, and a second output terminal of the carrier processing unit 102 is connected with an input terminal of the second modulation unit 302.

[0050] The phase-shifting angle processing unit 101 generates a phase-shifting angle according to the DC bus voltage signal or the DC bus capacitor current signal, and the carrier processing unit 102 generates a target carrier signal according to the phase-shifting angle and a reference carrier signal.

[0051] In the embodiment, the first output terminal of the carrier processing unit 102 is used to output a first carrier signal in the target carrier signal, and the second output terminal of the carrier processing unit 102 is used to output a second carrier signal in the target carrier signal.

[0052] In the embodiment, the phase-shifting angle processing unit 101 can be a proportional controller, the phase-shifting angle processing unit 101 can also be a proportional integral controller, and the phase-shifting angle processing unit 101 can also be a proportional quasi-integral controller. Of course, the phase-shifting angle processing unit 101 can process the DC bus voltage signal V dc or the DC bus capacitor current signal i dc by a disturbance observation method or a conductance increment method to generate an optimal phase-shifting angle.

[0053] In the embodiment, the phase-shifting angle is dynamically obtained based on the DC bus voltage signal or the DC bus capacitor current signal, and the value range of the dynamic phase-shifting angle is [-π, π], that is, the phase-shifting angle can be 0, the phase-shifting angle can also be -π, the phase-shifting angle can also be π, and of course, the phase-shifting angle can also be any value in [-π, π]. The application does not make specific limitations on this. It should be noted that when the phase-shifting angle is 0, the target carrier signal is the reference carrier signal, that is, any two carrier signals in the target carrier signal are the same. When the phase-shifting angle is not 0, if the target carrier signal includes the first carrier signal and the second carrier signal, the first carrier signal is different from the second carrier signal. It should be noted that one of the first carrier signal and the second carrier signal can be the reference carrier signal, and both the first carrier signal and the second carrier signal can not be the reference carrier signal, as long as the phase difference between the first carrier signal and the second carrier signal is the phase-shifting angle. In this way, the self-loss of the DC bus capacitor is reduced, the life of the capacitor is improved, the system reliability is ensured, and the efficiency of the converter is improved.

[0054] In an implementable scenario, the control circuit generates the phase-shifting angle dc by the DC bus voltage signal V dc or the DC bus capacitor current signal i , and the carrier processing unit 102 performs phase shift processing on the reference carrier signal C based on the phase shift angle o to generate a target carrier signal. Further, the control circuit compares the target carrier signal with the generated modulation signal m ABC to generate a control signal S ABC for driving the switching tubes in the respective converters. The modulation signal m ABC includes a first modulation signal m 1ABC and a second modulation signal m 2ABC , and the control signal S ABC includes a first control signal S 1ABC and a second control signal S 2ABC ; the first control signal S 1ABC includes signals for controlling each switching tube in the first converter 40, and when the first converter and the second converter circuit topology is a three-phase H-bridge, the first control signal S 1A1 includes signals S 1B1 , S 1C1 , S 1A2 , S 1B2 , and S 1C2 . The second control signal S 2ABC includes signals for controlling each switching tube in the second converter 50, and includes signals S 2A1 , S 2B1 , S 2C1 , S 2A2 , S 2B2 , and S 2C2 . When different types of topologies such as DNPC and ANPC are used, corresponding control signals can also be generated.

[0055] It should be noted that the phase shift angle is determined based on the DC bus voltage signal V dc or the DC bus capacitor current signal i dc , and the DC bus voltage signal V dc or the DC bus capacitor current signal i dc is affected by the power factor (PF) and the modulation coefficient. Referring to FIG. 3, Figure 8 Figure 8 A in FIG. 3 shows a result diagram of the DC bus capacitor current signal and the phase shift angle when the power factor PF is 1 in the embodiment of the present application;

[0056] Figure 8 ​Figure B shows a schematic diagram of the DC bus capacitor current signal and phase shift angle when the power factor PF is 0 in this embodiment of the application. Thus, by using the DC bus voltage signal or the DC bus capacitor current signal, a dynamic phase shift angle is determined. Based on the dynamic phase shift angle and the reference carrier signal, multiple control signals are generated so that at least two converters work collaboratively according to their respective control signals. This reduces the DC bus capacitor ripple current of at least two converters, reduces the self-loss of the DC bus capacitor, improves capacitor lifespan, ensures system reliability, and improves converter efficiency. Furthermore, due to the reduction in DC bus capacitor current ripple, fewer capacitors are needed in parallel to meet the normal and reliable operation of the converter, reducing the cost of the capacitors themselves. Additionally, fewer capacitors are needed in parallel to ensure current withstand capability, effectively reducing the bus capacitor volume.

[0057] In other embodiments of this application, since the phase shift angle is based on the DC bus voltage signal V dc or DC bus capacitor current signal i dc The obtained DC bus voltage signal V dc or DC bus capacitor current signal i dc Since the power factor and modulation coefficient are affected, the phase shift angle can be determined offline under different values ​​of apparent power, power factor and modulation coefficient, and a relationship mapping table can be established. Furthermore, based on the current actual operating condition parameters, namely apparent power, power factor and modulation coefficient, the relationship mapping table is searched to obtain the optimal phase shift angle, thereby achieving the purpose of suppressing DC bus capacitor current ripple.

[0058] In other embodiments of this application, when the first converter is a grid-side rectifier and the second converter is a motor-side inverter, the second modulation signal generation unit generates a second modulation signal based on the second voltage signal, the second current signal, and the rotational speed or position of the motor rotor. In one implementation scenario, referring to... Figure 3 As shown, for Figure 3 The circuit topology diagram of the three-phase common DC bus converter shown is illustrated in the diagram, where the second modulation signal m is determined. 2ABC At that time, the control circuit inputs the second voltage signal V to the modulation signal generation unit. 2ABC Second current signal i 2ABC It is obtained from the rotational speed n or position θ of the motor rotor.

[0059] In other embodiments of this application, when the first converter is a grid-side rectifier and the second converter is a load-side inverter, the second modulation signal generation unit generates a second modulation signal based on the second voltage signal, the second current signal, and the DC bus voltage signal. In one implementation scenario, refer to... Figure 2 As shown, for Figure 2The circuit topology diagram of the three-phase common DC bus converter is shown. In the case of determining that the first converter is a grid-side rectifier and the second converter is a load-side inverter, the second modulation signal m 2ABC is obtained by the second voltage signal V 2ABC , the second current signal i 2ABC and the DC bus voltage signal V dc input to the modulation signal generation unit.

[0060] In other embodiments of the present application, in the case of determining that the first converter is a grid-side rectifier and the second converter is a motor-side inverter, the second modulation signal generation unit generates the second modulation signal according to the second voltage signal, the second current signal, and the speed or position of the motor rotor. In one implementation scenario, the second voltage signal is the voltage signal V Figure 3 The circuit topology diagram of the three-phase common DC bus converter is shown. In the case of determining that the first converter is a grid-side rectifier and the second converter is a motor-side inverter, the second modulation signal m 2ABC is obtained by the second voltage signal V 2ABC , the second current signal i 2ABC and the speed n or position θ of the motor rotor.

[0061] In other embodiments of the present application, in the case of determining that the first converter is a grid-side rectifier and the second converter is a motor-side inverter, the second modulation signal generation unit generates the second modulation signal according to the second voltage signal, the second current signal, and the speed or position of the motor rotor. In one implementation scenario, the second voltage signal is the voltage signal V Figure 4 and Figure 5 The circuit topology diagram of the three-phase common DC bus converter is shown. In the case of determining that the first converter is a grid-side rectifier and the second converter is a motor-side inverter, the first voltage signal can be the voltage signal V 1ABC of the three-phase alternating voltage of the first converter 40, the first voltage signal can also be the alternating voltage signal V gABC provided by the power supply, the second voltage signal can be the voltage signal V 2ABC of the three-phase alternating voltage of the second converter 50, and the second voltage signal can also be the alternating voltage signal V gABC provided by the power supply.

[0062] As known from the above, the control circuit determines a dynamic phase shift angle based on the DC bus voltage signal or the DC bus capacitor current signal at the current moment, and then obtains a plurality of target carrier signals generated based on the dynamic phase shift angle and the reference carrier signal, and any two carrier signals in the plurality of target carrier signals are different. Finally, based on the plurality of target carrier signals, a plurality of control signals are generated to enable the at least two converters to work cooperatively according to the respective control signals, thereby reducing the common DC bus capacitor ripple current of the at least two converters, reducing the self-loss of the DC bus capacitor, improving the service life of the capacitor, ensuring the system reliability, and improving the efficiency of the converter. At the same time, due to the reduction of the DC bus capacitor current ripple, fewer capacitors in parallel can meet the normal and reliable operation of the converter, thereby reducing the cost of the capacitor itself. Further, fewer capacitors in parallel can effectively reduce the volume of the bus capacitor.

[0063] In some embodiments, one of the first converter and the second converter in the control circuit of the bus capacitor ripple current in the common DC bus converter is a grid-side rectifier, and the other is a load-side inverter. Here, the first converter is taken as the grid-side rectifier, and the second converter is taken as the load-side inverter for illustration, with reference to Figure 9 Figure 9 Fig. 6 shows a structure schematic diagram of another control circuit of a bus capacitor ripple current in a common DC bus converter provided by an embodiment of the application. The first converter 40 in the control circuit 100 of the bus capacitor ripple current in the common DC bus converter is a grid-side rectifier, and the second converter 50 is a load-side inverter. The control circuit 100 further includes a reactive power injection unit 60, wherein

[0064] The output end of the reactive power injection unit 60 is connected with the input end of the first modulation signal generation unit 201.

[0065] The reactive power injection unit 60 determines the reactive power of the load-side inverter 50 according to the second voltage signal and the second current signal, adjusts the amplitude of the first voltage signal and / or the amplitude of the first current signal based on the reactive power, so that the first converter control unit 20 controls the grid-side rectifier based on the adjusted first voltage signal and / or the adjusted first current signal.

[0066] In the embodiment of the application, the reactive power injection unit 60 uses the second voltage signal V 2ABC and the second current signal i 2ABC of the second converter 50 to determine whether the reactive power Q is injected into the second converter 50. In the case where it is determined that the reactive power Q is injected into the second converter 50, the amplitude of the first voltage signal V 1ABC and / or the amplitude of the first current signal i 1ABC ​The magnitude of the first voltage signal and / or the first current signal is adjusted based on the average reactive power, so that the same reactive power Q is injected into the first converter 40. In this way, the reactive power is injected into the grid-side rectifier without increasing hardware, effectively suppressing the high-frequency ripple current of the DC bus capacitor, reducing the self-loss of the DC bus capacitor, improving the life of the capacitor, ensuring system reliability, and improving the efficiency of the converter. At the same time, due to the reduction of the DC bus capacitor current ripple, fewer capacitors are needed to meet the normal and reliable operation of the converter, reducing the cost of the capacitor itself. Further, fewer capacitors are connected in parallel to ensure current resistance, effectively reducing the volume of the bus capacitor.

[0067] In some embodiments, the first converter 40 of the control circuit 100 of the bus capacitor ripple current in the common DC bus converter is M grid-side rectifiers, and the second converter 50 is a load-side inverter, wherein,

[0068] The reactive power injection unit 60 averages the reactive power according to the number of grid-side rectifiers, obtains the average reactive power, adjusts the amplitude of the first voltage signal and / or the amplitude of the first current signal input to the mth first converter control unit based on the average reactive power, so that the mth first converter control unit controls the grid-side rectifier based on the adjusted first voltage signal and / or the adjusted first current signal. M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M.

[0069] In an embodiment of the present application, if the number of load-side inverters is one, after it is determined that the load-side inverter injects reactive power, the reactive power injection unit 60 averages the reactive power injected in the load-side inverter according to the number of grid-side rectifiers, obtains the average reactive power, and adjusts the amplitude of the first voltage signal and / or the amplitude of the first current signal input to the first converter control unit 20 based on the average reactive power. Then, the first converter control unit 20 generates a new first modulation signal based on the adjusted first voltage signal and / or the adjusted first current signal, and generates a new first control signal based on the new first modulation signal and the target carrier signal to control the switch tube of the grid-side rectifier.

[0070] In another embodiment of the present application, if the number of load-side inverters is N, the reactive power injection unit 60 determines that at least part of the load-side inverters among the N load-side inverters inject reactive power; obtains a sum of the reactive power injected by the at least part of the load-side inverters, and divides the sum of the reactive power according to the number of grid-side rectifiers to obtain divided reactive power, and adjusts the amplitude of the first voltage signal and / or the amplitude of the first current signal input to the mth first converter control unit based on the divided reactive power; then, the mth first converter control unit generates a new first modulation signal based on the adjusted first voltage signal and / or the adjusted first current signal, and generates a new first control signal based on the new first modulation signal and the target carrier signal to control the switching tube of the grid-side rectifier.

[0071] It should be noted that since injecting reactive power into the grid-side rectifier will cause additional loss, after adopting the carrier phase-shifted control, if the suppression effect of the high-frequency ripple current meets the tolerance of the capacitor itself, no additional reactive power is injected.

[0072] In some embodiments, referring to FIG. 1, Figure 10 Figure 10 It is shown that the structure of the control circuit of the bus capacitor ripple current in the common DC bus converter provided by another embodiment of the present application, it should be noted that in the embodiment of the present application, the control circuit 100 can include a reactive power injection unit 60, and can also not include a reactive power injection unit 60, Figure 10 The control circuit 100 shown in FIG. 1 is described by including a reactive power injection unit 60. The first converter 40 of the control circuit 100 of the bus capacitor ripple current in the common DC bus converter is M grid-side rectifiers, and the second converter 50 is N load-side inverters, wherein,

[0073] The control circuit includes M first converter control units and N second converter control units, the M first converter control units include M first modulation signal generation units and M first modulation units, the N second converter control units include N second modulation signal generation units and N second modulation units, and M and N are both integers greater than or equal to 1, wherein,

[0074] The carrier processing unit 102 generates M+N first sub-phase-shift angles according to the phase-shift angle and the number of converters M+N, generates M+N target carrier signals based on each first sub-phase-shift angle and a reference carrier signal, and the phase difference of every two adjacent phase-shift angles in the first sub-phase-shift angle is equal;

[0075] ​The i th converter control unit in the M+N converters modulates the j th target carrier signal, i is an integer greater than or equal to 1 and less than or equal to M+N, j is an integer greater than or equal to 1 and less than or equal to M+N, and the M grid-side rectifiers and the N load-side inverters form the M+N converters.

[0076] In the embodiments of the present application, the control circuit can be applied to a common DC bus converter system composed of 1 grid-side rectifier and 1 load-side inverter; the control circuit can be applied to a common DC bus converter system composed of at least two grid-side rectifiers and 1 load-side inverter; the control circuit can be applied to a common DC bus converter system composed of 1 grid-side rectifier and at least two load-side inverters; and the control circuit can be applied to a common DC bus converter system composed of at least two grid-side rectifiers and at least two load-side inverters.

[0077] In the embodiments of the present application, for the common DC bus converter system composed of N load-side inverters and M grid-side rectifiers, the phase shift angle obtained from the DC bus capacitor current signal is equally divided according to the number of converters to obtain M+N first sub-phase shift angles, and the corresponding control signals are obtained by pulse modulation of the modulating signals generated by each modulating signal generation unit and the carrier signals after phase shift, and the corresponding converters are controlled by the control signals. It should be noted that the target carrier signal includes multiple carrier signals, and the same carrier signal can modulate different modulating signals, of course, the same carrier signal can only modulate one modulating signal, and the present application does not make specific limitations thereon. Herein, in the embodiments of the present application, the same carrier signal can only modulate one modulating signal. It should be further noted that each first converter control unit in the control circuit is used to control the corresponding first converter, and each second converter control unit is used to control the corresponding second converter.

[0078] In some embodiments, referring to Figure 11 , it is shown that Figure 11 It is shown that the structure of the control circuit of the bus capacitor ripple current in another common DC bus converter provided by another embodiment of the present application, it should be noted that in the embodiments of the present application, the control circuit 100 can include a reactive power injection unit 60, or can not include a reactive power injection unit 60, Figure 11 The control circuit 100 shown in the figure is described by including the reactive power injection unit 60. The first converter 40 of the control circuit 100 of the bus capacitor ripple current in the common DC bus converter is M grid-side rectifiers, and the second converter 50 is N load-side inverters, wherein,

[0079] The control circuit includes M first converter control units and N second converter control units, the M first converter control units include M first modulation signal generating units and M first modulation units, the N second converter control units include N second modulation signal generating units and N second modulation units, and M and N are integers greater than or equal to 1, wherein

[0080] In a case where the target carrier signal includes one first carrier signal and one second carrier signal, the M first converter control units are modulated by the first carrier signal, and the N second converter units are modulated by the second carrier signal.

[0081] In the embodiment, the phase shift angle processing unit 101 generates a phase shift angle based on the DC bus voltage signal or the DC bus capacitor current signal, generates two target carrier signals, i.e., a first carrier signal and a second carrier signal, based on the phase shift angle and the reference carrier signal, and the phase difference between the first carrier signal and the second carrier signal is the phase shift angle. Further, the M first converter control units are modulated by the first carrier signal, and the N second converter units are modulated by the second carrier signal. In this way, the same carrier signal is used to modulate different modulation signals in the embodiment, the number of generated carrier signals is reduced, and the system computing resources are saved.

[0082] In some embodiments, the first converter and the second converter in the control circuit of the bus capacitor ripple current in the common DC bus converter are one of the grid-side rectifier, the grid-side inverter, and the load-side inverter, and the total number of the first converter and the second converter is P, the control circuit includes P converter control units, the P converter control units include P modulation signal generating units and P modulation units, and P is an integer greater than or equal to 2, wherein

[0083] The carrier processing unit generates P second phase shift angles based on the phase shift angle and the total number P, generates P target carrier signals based on each second phase shift angle and the reference carrier signal, and the phase difference between every two adjacent phase shift angles in the second phase shift angles is equal.

[0084] In this embodiment, for a common DC bus converter system composed of P grid-side rectifiers, grid-side inverters, or load-side inverters, the phase shift angle obtained from the DC bus capacitor current signal is evenly divided according to the total number P to obtain P second sub-phase shift angles. The phase-shifted carrier signal is then pulse-modulated one by one with the modulation signal generated by each modulation signal generation unit to obtain corresponding control signals. These control signals are then used to control the corresponding converters. It should be noted that the target carrier signal includes multiple carrier signals. The same carrier signal can modulate different modulation signals; conversely, the same carrier signal can also modulate only one modulation signal. This application does not impose specific limitations on this. Here, in this embodiment, the same carrier signal can only modulate one modulation signal.

[0085] It should be noted that since the load inverters in the converter system are parallel converters, and the converter system completes the power distribution among multiple load inverters, there is no need for reactive power injection. Carrier phase shift control can be performed only based on the high-frequency ripple current.

[0086] In some embodiments, refer to Figure 12 As shown, Figure 12 The diagram shown is a structural schematic of another carrier signal generation unit provided in an embodiment of this application. The carrier signal generation unit 10 further includes: a root mean square (RMS) processing unit 103, wherein...

[0087] The output terminal of the root mean square processing unit 103 is connected to the input terminal of the phase angle processing unit 101;

[0088] The root mean square (RMS) processing unit 103 obtains the effective value of the DC bus voltage signal or the effective value of the DC bus capacitor current signal based on the DC bus voltage signal or the DC bus capacitor current signal, so that the phase shift angle processing unit generates a phase shift angle based on the effective value.

[0089] In this embodiment of the application, the root mean square processing unit 103 processes the DC bus voltage signal V. dc Or the DC bus capacitor current signal i dc The root mean square (RMS) calculation is performed to obtain the effective value of the DC bus voltage signal or the effective value of the DC bus capacitor current signal. Further, the phase shift angle processing unit 101 generates the final phase shift angle based on the input effective value. Thus, by obtaining the DC bus voltage signal or DC bus current signal, a dynamic phase shift angle is determined. Based on the dynamic phase shift angle and the reference carrier signal, multiple control signals are generated to enable at least two converters to work collaboratively according to their respective control signals, thereby reducing the DC bus ripple capacitor current of at least two converters.

[0090] In some embodiments, refer to Figure 13 As shown,Figure 13 Fig. 6 shows a structure diagram of another carrier signal generation unit provided by the embodiment of the present application. If the signal input to the root mean square processing unit 103 is a DC bus voltage signal, the carrier signal generation unit 10 further comprises a filter 104, wherein,

[0091] The output end of the filter 104 is connected with the input end of the root mean square processing unit 103.

[0092] The filter 104 is used to obtain the high-frequency component of the DC bus voltage signal, so that the root mean square processing unit calculates the effective value of the DC bus voltage signal according to the high-frequency component of the DC bus voltage signal.

[0093] In the embodiment of the present application, the root mean square processing unit 103 performs Fourier decomposition on the DC bus voltage signal V dc The effective values of the high-frequency components are obtained by squaring the effective values of different frequencies and taking the square root.

[0094] In the embodiment of the present application, since the DC bus voltage signal is composed of a DC voltage component and a high-frequency AC voltage component, only the high-frequency voltage component of the DC bus voltage signal corresponds to the high-frequency ripple current, and therefore, the filter is needed to obtain the high-frequency component of the DC bus voltage signal to represent the size of the ripple current. In this way, the dynamic phase shift angle is determined by the obtained high-frequency component of the DC bus voltage signal, and then a plurality of control signals are generated according to the dynamic phase shift angle and the reference carrier signal, so that the at least two converters work cooperatively according to the respective control signals, thereby reducing the DC bus capacitor ripple current of the at least two converters.

[0095] The embodiment of the present application provides a device, referring to Figure 14 Fig. 2 shows a structure diagram of the device of the embodiment of the present application, Figure 14 Fig. 2 shows a structure diagram of the device of the embodiment of the present application, Figure 14 The device 200 shown in Fig. 2 comprises the carrier signal generation unit 10 shown in the above embodiment, Figures 6 to 7 、 Figures 9 to 13 The control circuit 100 for the bus capacitor ripple current in any common DC bus converter provided by the embodiment of the present application.

[0096] The device 200 in the present application is a device with power conversion function, which can be a frequency converter or a UPS device. The frequency converter is a power control device for controlling the AC motor by changing the frequency of the motor operating power supply, and the UPS device is a constant voltage and constant frequency uninterruptible power supply device with energy storage function. The frequency converter includes but is not limited to air conditioning equipment and refrigerator equipment.

[0097] Those skilled in the art will appreciate that embodiments of the application can be readily used as software, hardware, or a combination of software and hardware. In one example, embodiments of the application can be implemented in software and / or firmware. In one embodiment, programming instructions are provided to a processor (or processors) of a mobile device to configure the processor (or processors) to provide the functionality of the application. In another embodiment, the programming instructions are provided in a general use software package, which can be used with multiple mobile devices, or in a specific use software package, which is used in a limited environment. Alternatively, embodiments of the application can be implemented using special purpose software or hardware.

[0098] The present application is described in reference to the drawings, which are as follows: Figure 1 Figure 1 The present application is described in reference to the drawings, which are as follows:

[0099] The present application is described in reference to the drawings, which are as follows: Figure 1 Figure 1 The present application is described in reference to the drawings, which are as follows:

[0100] The present application is described in reference to the drawings, which are as follows: Figure 1 Figure 1 The present application is described in reference to the drawings, which are as follows:

[0101] The present application is described in reference to the drawings, which are as follows:​​​

Claims

1. A control circuit for bus capacitor ripple current in a common DC bus converter, characterized by, The control circuit comprises a carrier signal generating unit, a first converter control unit, a second converter control unit, a first converter and a second converter, and the first converter and the second converter are connected to the same DC bus, The output end of the carrier signal generating unit is connected to the input end of the first converter control unit and the input end of the second converter control unit respectively, the output end of the first converter control unit is connected to the first converter, and the output end of the second converter control unit is connected to the second converter; The carrier signal generating unit generates a target carrier signal according to a DC bus voltage signal or a DC bus capacitance current signal of the DC bus and a reference carrier signal; The first converter control unit generates a first control signal for switching control of a switching tube in the first converter according to a first voltage signal of three-phase alternating current voltage of the first converter, a first current signal of three-phase current, the DC bus voltage signal and a first carrier signal in the target carrier signal; The second converter control unit generates a second control signal for switching control of a switching tube in the second converter according to a second voltage signal of three-phase alternating current voltage of the second converter, a second current signal of three-phase current and a second carrier signal in the target carrier signal; The first converter control unit comprises a first modulation signal generating unit and a first modulation unit, wherein, The output end of the first modulation signal generating unit is connected to the input end of the first modulation unit, and the output end of the first modulation unit is connected to the first converter; The first modulation signal generating unit generates a first modulation signal according to the first voltage signal, the first current signal and the DC bus voltage signal, and the first modulation unit generates the first control signal according to the first modulation signal and the first carrier signal; The second converter control unit comprises a second modulation signal generating unit and a second modulation unit, wherein the output end of the second modulation signal generating unit is connected to the input end of the second modulation unit, and the output end of the second modulation unit is connected to the second converter; The second modulation signal generating unit generates a second modulation signal according to the second voltage signal and the second current signal and one of the DC bus voltage signal or the speed or position of the motor rotor, and the second modulation unit generates the second control signal according to the second modulation signal and the second carrier signal; The carrier signal generating unit comprises a phase shift angle processing unit and a carrier processing unit, wherein, The output end of the phase shift angle processing unit is connected to the input end of the carrier processing unit, the first output end of the carrier processing unit is connected to the input end of the first modulation unit, and the second output end of the carrier processing unit is connected to the input end of the second modulation unit; The phase-shifting angle processing unit generates a phase-shifting angle according to the DC bus voltage signal or the DC bus capacitor current signal, and the carrier processing unit generates the target carrier signal according to the phase-shifting angle and the reference carrier signal. The first converter is a grid-side rectifier, and the second converter is a load-side inverter, and the control circuit further comprises a reactive power injection unit, wherein The output end of the reactive power injection unit is connected with the input end of the first modulation signal generation unit. The reactive power injection unit determines the reactive power injected into the load-side inverter according to the second voltage signal and the second current signal, adjusts the amplitude of the first voltage signal and / or the amplitude of the first current signal based on the reactive power, so that the first converter control unit controls the grid-side rectifier based on the adjusted first voltage signal and / or the adjusted first current signal.

2. The control circuit of claim 1, wherein, The first converter is M grid-side rectifiers, the reactive power injection unit averages the reactive power according to the number of the grid-side rectifiers to obtain an equally divided reactive power, adjusts the amplitude of the first voltage signal and / or the amplitude of the first current signal input to the mth first converter control unit based on the equally divided reactive power, so that the mth first converter control unit controls the grid-side rectifier based on the adjusted first voltage signal and / or the adjusted first current signal, M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M.

3. The control circuit according to claim 1 or 2, characterized in that, The first converter is M grid-side rectifiers, the second converter is N load-side inverters, the control circuit comprises M first converter control units and N second converter control units, the M first converter control units comprise M first modulation signal generation units and M first modulation units, the N second converter control units comprise N second modulation signal generation units and N second modulation units, and M and N are both integers greater than or equal to 1, wherein The carrier processing unit generates M+N first sub-phase-shifting angles according to the phase-shifting angle and the number M+N of converters, generates M+N target carrier signals based on each first sub-phase-shifting angle and the reference carrier signal, and the phase difference of every adjacent two phase-shifting angles in the first sub-phase-shifting angles is equal; The ith converter control unit of the M+N converters modulates the jth target carrier signal, the i is an integer greater than or equal to 1 and less than or equal to M+N, the j is an integer greater than or equal to 1 and less than or equal to M+N, and the M grid-side rectifiers and the N load-side inverters constitute the M+N converters.

4. The control circuit according to claim 1 or 2, characterized in that, The first converter is M grid-side rectifiers, the second converter is N load-side inverters, the control circuit comprises M first converter control units and N second converter control units, the M first converter control units comprise M first modulation signal generating units and M first modulation units, the N second converter control units comprise N second modulation signal generating units and N second modulation units, and M and N are integers greater than or equal to 1, wherein, In the case where the target carrier signal comprises one first carrier signal and one second carrier signal, the M first converter control units are modulated by the first carrier signal, and the N second converter units are modulated by the second carrier signal.

5. The control circuit according to claim 1 or 2, characterized in that, The first converter and the second converter are one of a grid-side rectifier, a grid-side inverter and a load-side inverter, and the total number of the first converter and the second converter is P, the control circuit comprises P converter control units, the P converter control units comprise P modulation signal generating units and P modulation units, and P is an integer greater than or equal to 2, wherein, The carrier processing unit generates P second sub-phase shift angles according to the phase shift angle and the total number P, and generates P target carrier signals based on each second sub-phase shift angle and the reference carrier signal, and the phase difference of every adjacent two phase shift angles in the second sub-phase shift angles is equal.

6. The control circuit according to claim 1 or 2, characterized in that, The carrier signal generating unit further comprises a root mean square processing unit, wherein, The output end of the root mean square processing unit is connected with the input end of the phase shift angle processing unit. The root mean square processing unit obtains the effective value of the DC bus voltage signal or the effective value of the DC bus capacitor current signal according to the DC bus voltage signal or the DC bus capacitor current signal, so that the phase shift angle processing unit generates the phase shift angle according to the effective value.

7. The control circuit of claim 6, wherein, If the signal input to the root mean square processing unit is the DC bus voltage signal, the carrier signal generating unit further comprises a filter, wherein, The output end of the filter is connected with the input end of the root mean square processing unit. The filter is used to obtain the high-frequency component of the DC bus voltage signal, so that the root mean square processing unit calculates the effective value of the DC bus voltage signal according to the high-frequency component of the DC bus voltage signal.

8. An apparatus, comprising: The device comprises the control circuit of the bus capacitor ripple current of the common DC bus converter according to any one of claims 1 to 7.

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