AC load driving device and electrical equipment

Abstract

According to the alternating current load driving device and the electrical equipment, a voltage division circuit is arranged between the input end of a three-phase rectifier bridge and an intermediate voltage node, two capacitors are connected between the intermediate voltage node and the two output ends of a three-phase rectifier circuit respectively, and the voltage division circuit controls connection and disconnection between the different output ends and the intermediate voltage node. Therefore, the voltage balance of the two capacitors is maintained, two power levels are respectively connected with the two capacitors in parallel, one power level takes an intermediate voltage node as a control ground node, and the other power level takes a reference ground of the three-phase rectification circuit as a control ground node. The peak value of the input voltage of the two power levels can be only half of the peak value of the voltage output by the three-phase rectifier bridge, so that the requirements on the working voltage specifications of the power level circuit and the alternating current load connected subsequently are effectively reduced, the cost of electrical equipment is reduced, and the safety is improved to a certain extent.

Description

Technical Field

[0001] The utility model relates to the field of power electronics, in particular to an AC load driving device and electrical equipment. Background Art

[0002] Some high-power electrical equipment (such as commercial air conditioners) is typically driven by three-phase AC power. In the drive device, after the three-phase AC input, the AC power is rectified into DC power to perform power factor correction, and then it is inverted as needed to drive the AC load. Taking the full-bridge rectifier circuit commonly used for 380V three-phase AC rectification as an example, the peak DC voltage of the rectified output can reach 800V, which places high requirements on the operating voltage specifications of subsequent power stage circuits (such as PFC circuits, inverter circuits, etc.). At the same time, it also places high requirements on the operating voltage specifications of power loads (such as motors, compressors, etc.). This further increases the production cost of electrical equipment.

[0003] Therefore, it is desired to provide an AC load driving device that has lower requirements on the power level after rectification and the AC load operating voltage specifications. Utility Model Content

[0004] In view of this, embodiments of the present invention provide an AC load driving device and an electrical apparatus to reduce the power level and operating voltage specification requirements of the AC load, thereby reducing manufacturing costs and improving safety.

[0005] In a first aspect, an embodiment of the present invention provides an AC load driving device, the AC load driving device comprising:

[0006] A three-phase rectifier circuit having three input inductors and a three-phase rectifier bridge, wherein the three-phase rectifier bridge has a first input terminal, a second input terminal, a third input terminal, a first output terminal, and a second output terminal, wherein the three input inductors are respectively connected between each input terminal of the three-phase alternating current power and the first input terminal, the second input terminal, and the third input terminal, and the three-phase rectifier bridge is used to output a DC voltage from the first output terminal and the second output terminal;

[0007] A voltage divider circuit is connected to each input terminal of the three-phase rectifier bridge, and an output terminal of the voltage divider circuit is connected to an intermediate voltage node;

[0008] a first capacitor connected between the first output terminal and the intermediate voltage node;

[0009] a second capacitor connected between the second output terminal and the intermediate voltage node;

[0010] A first power stage is connected in parallel with the first capacitor, uses the intermediate voltage node as a control ground node, and is used to input a voltage across the first capacitor to drive a first AC load;

[0011] A second power stage is connected in parallel with the second capacitor, with the second output terminal as a control ground node, and is used to input a voltage across the second capacitor to drive a second AC load;

[0012] Optionally, the voltage divider circuit includes:

[0013] a first switch unit, connected between the first input terminal of the three-phase rectifier bridge and the intermediate voltage node;

[0014] a second switch unit connected between the second input terminal of the three-phase rectifier bridge and the intermediate voltage node; and

[0015] a third switch unit, connected between the third input terminal of the three-phase rectifier bridge and the intermediate voltage node;

[0016] Optionally, the peak value of the input voltage of the first power stage is 40% to 60% of the peak value of the voltage output by the three-phase rectifier bridge, and the peak value of the input voltage of the second power stage is 40% to 60% of the peak value of the voltage output by the three-phase rectifier bridge;

[0017] Optionally, the peak value of the input voltage of the first power stage is half of the peak value of the voltage output by the three-phase rectifier bridge; the peak value of the input voltage of the second power stage is half of the peak value of the voltage output by the three-phase rectifier bridge;

[0018] Optionally, the AC load driving device further includes:

[0019] a detection circuit, configured to detect a voltage across the first capacitor and output a first detection voltage, and to detect a voltage across the second capacitor and output a second detection voltage;

[0020] a control circuit, configured to control the voltage divider circuit to charge the first capacitor or the second capacitor according to the first detection voltage and the second detection voltage;

[0021] Optionally, the control circuit is configured to control the voltage divider circuit to charge the second capacitor when the voltage across the first capacitor is higher than the voltage across the second capacitor, and to control the voltage divider circuit to charge the first capacitor when the voltage across the second capacitor is higher than the voltage across the first capacitor;

[0022] Optionally, the control circuit is configured to control the voltage divider circuit to charge the first capacitor when the voltage across the first capacitor is lower than a predetermined threshold voltage, and to control the voltage divider circuit to charge the second capacitor when the voltage across the second capacitor is lower than a predetermined threshold voltage;

[0023] Optionally, the control circuit is configured to control a portion of the first switch unit, the second switch unit, and the third switch unit to be turned on or off according to different phase sectors of the three-phase alternating current to charge the first capacitor or the second capacitor, and the voltage divider circuit is configured to control the voltage across the first capacitor and the second capacitor to maintain a balance;

[0024] Optionally, the control circuit is configured to control the first switch unit and the third switch unit to be turned on and the second switch unit to be turned off in a first phase sector to charge the second capacitor, or to control the first switch unit and the third switch unit to be turned off and the second switch unit to be turned on in the first phase sector to charge the first capacitor;

[0025] The first phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is positive, the phase voltage corresponding to the second input terminal is negative, and the phase voltage corresponding to the third input terminal is positive in the three-phase alternating current;

[0026] Optionally, the control circuit is configured to control the first switch unit to be turned on and the second switch unit and the third switch unit to be turned off in the second phase sector to charge the second capacitor, or to control the second switch unit and the third switch unit to be turned on and the first switch unit to be turned off in the second phase sector to charge the first capacitor;

[0027] The second phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is positive, the phase voltage corresponding to the second input terminal is negative, and the phase voltage corresponding to the third input terminal is negative in the three-phase alternating current;

[0028] Optionally, the control circuit is configured to control the first switch to be turned on, the second switch unit to be turned on, and the third switch unit to be turned off in a third phase sector to charge the second capacitor; or,

[0029] In a third phase sector, the third switch is controlled to be turned on, and the first switch and the second switch are controlled to be turned off to charge the first capacitor;

[0030] The third phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is positive, the phase voltage corresponding to the second input terminal is positive, and the phase voltage corresponding to the third input terminal is negative in the three-phase alternating current.

[0031] Optionally, the control circuit is configured to control the second switch unit to be turned on and the first switch unit and the third switch unit to be turned off in a fourth phase sector to charge the second capacitor; or,

[0032] In a fourth phase sector, controlling the first switch unit to be turned on, the second switch to be turned off, and the third switch to be turned on to charge the first capacitor;

[0033] The fourth phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is negative, the phase voltage corresponding to the second input terminal is positive, and the phase voltage corresponding to the third input terminal is negative in the three-phase alternating current.

[0034] Optionally, the control circuit is configured to control the second switch unit to be turned on, the first switch unit to be turned off, and the third switch unit to be turned on in the fifth phase sector to charge the second capacitor; or,

[0035] In a fifth phase sector, controlling the first switch unit to be turned on, and the second switch unit and the third switch unit to be turned off to charge the first capacitor;

[0036] The fifth phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is negative, the phase voltage corresponding to the second input terminal is positive, and the phase voltage corresponding to the third input terminal is positive in the three-phase alternating current.

[0037] Optionally, the control circuit is configured to control the third switch unit to be turned on and the first switch unit and the second switch unit to be turned off in the sixth phase sector to charge the second capacitor; or,

[0038] In a sixth phase sector, the third switch unit is controlled to be turned off, and the first switch unit and the second switch unit are controlled to be turned on, so as to charge the first capacitor;

[0039] The sixth phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is negative, the phase voltage corresponding to the second input terminal is negative, and the phase voltage corresponding to the third input terminal is positive in the three-phase alternating current.

[0040] Optionally, the three-phase alternating current is a three-phase alternating current with an effective value of 380V, and the operating voltage specifications of the first power level and the second power level are not less than 600V;

[0041] Optionally, the first power stage is a first power module, and the second power stage is a second power module;

[0042] Optionally, the first capacitor is charged while also supplying power to the first power stage, and the second capacitor is charged while also supplying power to the second power stage;

[0043] Optionally, when the first capacitor is not charged, the first capacitor is discharged to supply power to the first power level, and when the second capacitor is not charged, the second capacitor is discharged to supply power to the second power level. In a second aspect, an electrical device is provided, comprising:

[0044] The AC load driving device according to the first aspect;

[0045] a first AC load connected to the first power stage of the AC load driving device;

[0046] The second AC load is connected to the second power stage of the AC load driving device.

[0047] Optionally, the electrical equipment is an air conditioner, and the first AC load and the second AC load are air conditioner compressors or fan motors.

[0048] The embodiment of the present invention provides a voltage divider circuit between the input end and the intermediate voltage node of the three-phase rectifier bridge, and connects two capacitors between the intermediate voltage node and the two output ends of the three-phase rectifier circuit respectively. The voltage divider circuit controls the on-off between different output ends and the intermediate voltage node, thereby maintaining the voltage balance of the two capacitors. Furthermore, by connecting two power stages in parallel with the two capacitors, one power stage uses the intermediate voltage node as the control ground node, and the other power stage uses the reference ground of the three-phase rectifier circuit as the control ground node, the peak value of the input voltage of the two power stages can be only 40% to 60% of the peak value of the voltage output by the three-phase rectifier bridge. Preferably, the peak value of the input voltage of the two power stages is only half of the peak value of the voltage output by the three-phase rectifier bridge, effectively reducing the requirements for the operating voltage specifications of the power stage circuit and the subsequently connected AC load, reducing the cost of the electrical equipment, and improving safety to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0050] Figure 1 It is a circuit diagram of an electrical device driven by three-phase alternating current in the prior art;

[0051] Figure 2 It is a circuit block diagram of the electrical equipment according to an embodiment of the present utility model;

[0052] Figure 3 This is a circuit diagram of an implementation of the electrical device of the embodiment of the present utility model;

[0053] Figure 4 It is the working waveform diagram of each phase voltage of three-phase alternating current;

[0054] Figure 5 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the first phase sector according to the embodiment of the present invention;

[0055] Figure 6 Schematic diagram of a current path for charging a first capacitor when the three-phase alternating current is in the first phase sector according to an embodiment of the present invention;

[0056] Figure 7 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the second phase sector according to the embodiment of the present invention;

[0057] Figure 8 1 is a schematic diagram of a current path for charging the first capacitor when the three-phase alternating current is in the second phase sector according to an embodiment of the present invention;

[0058] Figure 9 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the third phase sector according to the embodiment of the present invention;

[0059] Figure 10 Schematic diagram of a current path for charging the first capacitor when the three-phase alternating current is in the third phase sector according to an embodiment of the present invention;

[0060] Figure 11 1 is a schematic diagram of a current path for charging the second capacitor when the three-phase alternating current is in the fourth phase sector according to an embodiment of the present invention;

[0061] Figure 12 1 is a schematic diagram of a current path for charging the first capacitor when the three-phase alternating current is in the fourth phase sector according to an embodiment of the present invention;

[0062] Figure 13 A schematic diagram of a current path for charging the second capacitor when the three-phase alternating current is in the fifth phase sector according to an embodiment of the present invention;

[0063] Figure 14 1 is a schematic diagram of a current path for charging the first capacitor when the three-phase alternating current is in the fifth phase sector according to an embodiment of the present invention;

[0064] Figure 15 A schematic diagram of a current path for charging the second capacitor when the three-phase alternating current is in the sixth phase sector according to an embodiment of the present invention;

[0065] Figure 16 It is a schematic diagram of the current path for charging the first capacitor when the three-phase alternating current is in the sixth phase sector according to an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The present application is described below based on the following embodiments, but the present application is not limited to these embodiments. In the detailed description of the present application below, certain specific details are described in detail. Those skilled in the art can fully understand the present application without the description of these details. To avoid obscuring the essence of the present application, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0067] Furthermore, persons of ordinary skill in the art will appreciate that the figures provided herein are for illustration purposes only and are not necessarily drawn to scale.

[0068] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit connected electrically or electromagnetically. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected" between two nodes, it can be directly coupled or connected to the other element or there can be intermediate elements. The connection between the elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between the two.

[0069] In the description of this application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance. In addition, in the description of this application, unless otherwise specified, "plurality" means two or more.

[0070] Figure 1 This is a circuit diagram of an electrical device driven by three-phase alternating current in the prior art. Figure 1 As shown, the electrical equipment of the prior art includes AC loads M1' and M2', and a drive circuit 1 for driving the AC loads. The drive circuit 1 includes a three-phase AC input port 11, inductors L1'-L3', a three-phase rectifier bridge 12, an output filter capacitor C1', and two power stages IPM1' and IPM2'. One end of the inductor L1'-L3' is respectively connected to one phase of the three-phase AC input port 11, and the other end is respectively connected to each input terminal of the three-phase rectifier bridge 12. The three-phase rectifier bridge includes six unidirectional conductive elements D1'-D6'. The unidirectional conductive elements can be diodes or thyristors. The output filter capacitor C1' is connected to the output port of the three-phase rectifier bridge 12. The power stages IPM1' and IPM2' are connected in parallel at the output port of the three-phase rectifier bridge 12, and are both driven by the voltage (v1'-v2') at the output port. Taking 380V three-phase AC power as an example, the peak DC voltage of its rectified output can reach approximately 800V. In other words, the peak DC voltage at the output port of the three-phase rectifier bridge can reach approximately 800V. To ensure normal operation of the equipment, the operating voltage specification of the power stages IPM1' and IPM2' needs to be above 800V. The power stages IPM1' and IPM2' of the existing technology generally adopt a 1200V specification. If the power stage is not stepped down, the subsequently driven AC loads, such as motors and compressors, also need to adopt products with an operating voltage specification of 800V or above. The higher operating voltage specification makes the product cost remain high.

[0071] In order to solve the above problems, the embodiments of the present invention propose an AC load driving device and electrical equipment, in which two capacitors connected in series are arranged at the output port of the three-phase rectifier bridge. By adding a voltage divider circuit, the current path from the input port to the two capacitors is controlled to be on and off in different AC phase sectors. Any one of the two capacitors can be charged as needed to maintain the balance of the capacitor voltage, and then the power stage is driven based on the voltage on the capacitor that only accounts for about half of the peak value of the output voltage of the three-phase rectifier bridge. As a result, the voltage peak at the input end of each power stage is halved when it is working, so that components with lower working voltage specifications can be selected to reduce production costs.

[0072] Figure 2 This is a circuit diagram of an electrical device according to an embodiment of the present utility model. Figure 2As shown, the electrical device of an embodiment of the present invention includes an AC load driving device 2 and a first AC load M1 and a second AC load M2 driven by the AC load driving device 2. When the electrical device is a power device, the AC loads M1 and M2 may be motors. When the electrical device is an air conditioner, the AC loads M1 and M2 may also be air conditioner compressors or fan motors. The AC load driving device 2 of this embodiment includes a three-phase AC input port 21, a three-phase rectifier circuit 22, a voltage divider circuit 23, a first capacitor C1, a second capacitor C2, and a first power stage IPM1 and a second power stage IPM2. The three-phase rectifier circuit 22 includes three input inductors L1-L3 and a three-phase rectifier bridge 22a. One end of the input inductors L1-L3 is connected to different phases of the three-phase AC input port 21, and the other end is connected to the first input terminal, the second input terminal, and the third input terminal of the three-phase rectifier bridge 22a, respectively. The three-phase rectifier bridge 22a outputs a rectified DC voltage from a first output terminal v1 and a second output terminal v2. The input of the voltage divider circuit 23 is connected to each input of the three-phase rectifier bridge 22a, and the output of the voltage divider circuit 23 is connected to the intermediate voltage node v0. A first capacitor C1 is connected between the first output terminal v1 and the intermediate voltage node v0. A second capacitor C2 is connected between the second output terminal v2 and the intermediate voltage node v0. A first power stage IPM1 is connected in parallel with the first capacitor C1, with the intermediate voltage node v0 serving as a control ground node. The voltage across the first capacitor is input to drive a first AC load M1. Specifically, the positive input terminal P1 of the first power stage is connected to the first output terminal v1, and the negative input terminal N1 of the first power stage is connected to the intermediate voltage node v0. The first power stage operates with the negative input terminal N1 as a reference ground. A second power stage IPM2 is connected in parallel with the second capacitor C2, with the second output terminal v2 serving as a control ground node. The voltage across the second capacitor is input to drive a second AC load M2. The first power stage IPM1 uses the intermediate voltage node v0 as its ground, resulting in a floating ground. The potential of the floating ground, i.e., the potential of the intermediate voltage node v0, is raised by the second capacitor C2. Thus, by controlling the voltage divider circuit 23, the DC voltage output by the three-phase rectifier circuit is evenly divided into two equal voltages, which act on the first capacitor C1 and the second capacitor C2 respectively. As a result, the operating voltage specifications of the first power stage IPM1 and the second power stage IPM2 are reduced to half of the existing technology, which can greatly reduce the production cost of the power stage. Figure 2 In the figure, the first power stage IPM1 is shown as a first power module, and the second power stage IPM2 is shown as a second power module. The first power module and the second power module receive direct current and convert it into alternating current to drive subsequent alternating current loads.

[0073] In this embodiment, the voltage divider circuit 23 is used to control the voltage across the first capacitor and the second capacitor to maintain a balance.

[0074] In some embodiments, the voltage divider circuit 23 controls the on / off state between multiple circuit nodes and the intermediate voltage node in the rectifier circuit, thereby changing the topology in the circuit, and then maintaining the voltage balance of the two capacitors by switching the circuit state. Specifically, a detection circuit 24 and a control circuit 25 can be further provided. The detection circuit 24 is used to detect the voltage across the first capacitor C1 and output a first detection voltage vsen1, and to detect the voltage across the second capacitor C2 and output a second detection voltage vsen2. The first detection voltage vsen1 and the second detection voltage vsen2 can be used to characterize the peak voltage, the effective value of the voltage across the capacitor, or the average value of the voltage in a specific time period, as long as they can reflect the state of the voltage across the capacitor. The control circuit 25 determines the voltage balance state of the first capacitor C1 and the second capacitor C2 based on the first detection voltage vsen1 and the second detection voltage vsen2, and controls the voltage divider circuit 23 to switch to different states to charge the first capacitor C1 to increase the voltage across the first capacitor C1, or to charge the second capacitor C2 to increase the voltage across the second capacitor C2.

[0075] The embodiment of the present invention sets a voltage divider circuit between the input end and the intermediate voltage node of the three-phase rectifier bridge, and connects two capacitors between the intermediate voltage node and the two output ends of the three-phase rectifier circuit respectively, so that the voltage divider circuit controls the on and off between different output ends and the intermediate voltage node, thereby maintaining the voltage balance of the two capacitors. Furthermore, by connecting two power stages in parallel with the two capacitors respectively, one power stage uses the intermediate voltage node as the control ground node, and the other power stage uses the reference ground of the three-phase rectifier circuit as the control ground node, the maximum operating voltage of the two power stages can be only half of the voltage peak value output by the three-phase rectifier bridge, effectively reducing the requirements for the operating voltage specifications of the power stage circuit and the subsequently connected AC load, reducing the cost of electrical equipment, and the reduction in the operating voltage specification reduces the hazard of electric shock, thereby improving safety to a certain extent.

[0076] The voltage divider circuit of this embodiment can be implemented in different ways. Figure 3 This is a circuit diagram of an implementation of the electrical device of the utility model embodiment. Figure 3 As shown, the voltage divider circuit 23 includes a first switch unit K1, a second switch unit K2, and a third switch unit K3. The first switch unit K1 is connected between the first input terminal a of the three-phase rectifier bridge 22a and the intermediate voltage node v0. The second switch unit K2 is connected between the second input terminal b of the three-phase rectifier bridge 22a and the intermediate voltage node v0. The third switch unit K3 is connected between the third input terminal c of the three-phase rectifier bridge 22a and the intermediate voltage node v0. The first switch unit K1, the second switch unit K2, and the third switch unit K3 are all bidirectional switch circuits, for example, they can be as follows Figure 3The figure shows a bidirectional switch circuit consisting of two insulated gate bipolar transistors (IGBTs). An IGBT is a fully controlled, voltage-driven power semiconductor device composed of a BJT (bipolar junction transistor) and a MOS (insulated gate field-effect transistor). It combines the advantages of a MOSFET's high input impedance and an GTR's low on-state voltage drop. Taking the first switch unit K1 as an example, two IGBTs Q1 and Q2 connected in series in reverse form the first switch unit K1. That is, the emitters of IGBTs Q1 and Q2 are interconnected. Due to the integrated fast recovery diodes (FRDs), when a turn-on voltage is applied to the control electrodes of IGBTs Q1 and Q2, current can flow from the left side of the figure to the right side through the body of device Q1 and the fast recovery diode of Q2, or from the right side to the left side through the body of device Q2 and the fast recovery diode of device Q1, achieving bidirectional current conduction. Similarly, the second switch unit K2 includes IGBT devices Q3 and Q4, and the third switch unit K3 includes IGBT devices Q5 and Q6. It should be understood that the first switch unit K1, the second switch unit K2, and the third switch unit K3 can also be bidirectional switch circuits constructed using other components, such as silicon carbide field-effect transistors (SiCMOSFETs), gallium nitride high electron mobility transistors (GaN HEMTs), etc.

[0077] In the present embodiment, the voltage divider circuit 23 and the control circuit 25 ( Figure 3 The first and second switching units (not shown) are configured to control a portion of the first switching unit K1, the second switching unit K2, and the third switching unit K3 to conduct in different modes according to different phase sectors of the three-phase alternating current to charge the first capacitor C1 or the second capacitor C2. That is, when it is detected that the voltage across the first capacitor C1 is relatively small, for example, when the difference between the average voltage of the first capacitor C1 and the second capacitor C2 reaches a preset threshold, or when the voltage across the first capacitor C1 is lower than a preset voltage threshold, the states of the first switching unit K1, the second switching unit K2, and the third switching unit K3 are controlled to form a current path for charging the first capacitor C1, thereby charging the first capacitor C1. When it is detected that the voltage across the second capacitor C2 is relatively small, for example, when the difference between the average voltage of the second capacitor C2 and the first capacitor C1 reaches a preset threshold, or when the voltage across the second capacitor C2 is lower than a preset voltage threshold, the states of the first switching unit K1, the second switching unit K2, and the third switching unit K3 are controlled to form a current path for charging the second capacitor C2, thereby charging the second capacitor C2.

[0078] For another example, when it is detected that the average voltage of the first capacitor C1 is lower than a preset voltage threshold, such as 380V, charging of the first capacitor C1 is triggered.

[0079] In some implementations, such as Figure 1 As shown in FIG, the control circuit 25 outputs a control signal ctrl according to the first detection voltage vsen1 and the second detection voltage vsen2. Figure 3 In the illustrated implementation, the control signal ctrl may include six sub-signals, which respectively control the six IGBT devices in the first switch unit K1 to the third switch unit K3 .

[0080] exist Figure 3 In the embodiment, the three-phase rectifier bridge 22a is a full-bridge rectifier circuit, including six unidirectional conducting elements D1-D6, which may be diodes or thyristors.

[0081] Figure 3 The voltage divider circuit 23 and the three-phase rectifier circuit 22 shown in the figure, together with the first capacitor C1 and the second capacitor C2, form a Vienna rectifier circuit. In the embodiment of the utility model, the voltage divider characteristic of the circuit is utilized to connect the first power stage IPM1 and the second power stage IPM2 in parallel with the first capacitor C1 and the second capacitor C2, respectively. The first power stage IPM1 adopts a floating ground method with the intermediate voltage node v0 as the control ground node, thereby significantly reducing the operating voltage specifications of the first power stage IPM1 and the second power stage IPM2 compared to the prior art, reducing the component requirements for the first power stage and the second power stage, and reducing production costs.

[0082] The following combination Figure 4-Figure 16 , a specific manner in which the voltage divider circuit partially conducts in different modes to charge the first capacitor or the second capacitor according to different phase sectors of the three-phase alternating current is described.

[0083] Figure 4 It is the working waveform of each phase voltage of three-phase alternating current. Figure 4 As shown, the voltage of three-phase AC power consists of three waveforms with different phases, each of which is a sinusoidal wave and offset in time by 120 degrees relative to each other. This configuration allows for more efficient and stable power transmission, while also better balancing the loads on generators and motors. In a three-phase AC system, a "phase sector" refers to a region of space or time divided according to the relative relationship between the three phases. Each phase sector represents the dominant position of one phase in the three-phase system relative to the other two. Since the phase difference between each phase is 120 degrees, the entire cycle can be divided into six phase sectors, each occupying 60 degrees. Within each sector, the voltage of the dominant phase gradually decreases over time, while the voltage of the next phase gradually increases, until dominance is transferred to the next phase in the next sector. Figure 4Figure 2 shows the waveforms of the voltages Va, Vb, and Vc at the input terminals a, b, and c of the rectifier bridge. In the following description, a three-bit binary sequence is used to represent different phase sectors. The first bit corresponds to the voltage Va, the second bit corresponds to the voltage Vb, and the third bit corresponds to the voltage Vc. A value greater than zero is marked as 1, and a value less than zero (i.e., negative) is marked as 0. Based on the above method, the state of the first phase sector is 101. In increments of 60°, the states of the second to sixth phase sectors are 100, 110, 010, 011, and 001, respectively.

[0084] First phase sector

[0085] When the three-phase AC power at the input port is in the first phase sector (that is, the phase voltage state is 101):

[0086] (1) If the second capacitor C2 needs to be charged, the specific process can be performed as described below. Figure 5 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the first phase sector according to the embodiment of the present invention. Figure 5 As shown, the control circuit 25 turns on the first and third switch units K1 and K3, and turns off the second switch unit K2. The voltage Va at the first input terminal a is higher than the voltage Vb at the second input terminal b. The corresponding phase current i1 (the path is indicated in red in the figure) flows from the first input inductor L1 through the first switch unit K1, then through the intermediate voltage node v0, the second capacitor C2, and the diode D5 to reach node b. From node b, it flows out through the second input inductor L2. Simultaneously, the voltage Vc at the third input terminal c is higher than the voltage Vb at the second input terminal b. The corresponding phase current i2 (the path is indicated in blue in the figure) flows from the third input inductor L3, through the third switch unit K3, then through the intermediate voltage node v0, the second capacitor C2, the diode D5, and from node b, out through the second input inductor L2.

[0087] Phase currents i1 and i2 charge the second capacitor C2 through different paths. While charging, the second capacitor C2 supplies power to the second power stage IPM2. Simultaneously, the first capacitor C1 discharges its stored charge to supply power to the first power stage IPM1, causing a voltage drop. Consequently, the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0088] (2) If the first capacitor C1 needs to be charged, the specific process can be performed as described below. Figure 6 Schematic diagram of the current path for charging the first capacitor when the three-phase alternating current is in the first phase sector of the present utility model. Figure 6As shown, the control circuit 25 controls the second switch unit K2 to turn on, while the first and third switch units K1 and K3 are turned off. At this point, the voltage Va at the first input terminal a is higher than the voltage Vb at the second input terminal b. The corresponding phase current i3 (indicated in red in the figure) flows from the first input inductor L1 through the diode D1, the first capacitor C1, and then through the intermediate voltage node v0, to the second switch unit K2, reaching the second input terminal b, and then flowing out through the second input inductor L2. At the same time, the voltage Vc at the third input terminal c is higher than the voltage Vb at the second input terminal b. The corresponding phase current i4 (the path shown in blue in the figure) flows from the third input inductor L3 through the diode D3, the first capacitor C1, and then through the intermediate voltage node v0, to the second switch unit K2, reaching the second input terminal b, and then flowing out through the second input inductor L2.

[0089] Phase currents i3 and i4 charge the first capacitor C1 through different paths. While charging, the first capacitor C1 supplies power to the first power stage IPM1. Simultaneously, the second capacitor C2 discharges its stored charge to supply power to the second power stage IPM2. This causes a voltage drop, and the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0090] Second phase sector

[0091] When the three-phase AC power at the input port is in the second phase sector (that is, the phase voltage state is 100):

[0092] (1) If the second capacitor C2 needs to be charged, the specific process can be performed as described below. Figure 7 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the second phase sector according to the embodiment of the present invention. Figure 7 As shown, the control circuit 25 controls the first switch unit K1 to turn on, and the second and third switch units K2 and K3 to turn off. The voltage Va at the first input terminal a is higher than the voltage Vb at the second input terminal b. The corresponding phase current i5 (the path is indicated in red in the figure) flows from the first input inductor L1 through the first switch unit K1, then through the intermediate voltage node v0, the second capacitor C2, the diode D5, and out from node b through the second input inductor L2. Simultaneously, the voltage Va at the first input terminal a is higher than the voltage Vc at the third input terminal c. The corresponding phase current i6 (the path is indicated in blue in the figure) flows from the first input inductor L1 through the first switch unit K1, then through the intermediate voltage node v0, the second capacitor C2, the diode D6, and out from node c through the third input inductor L3.

[0093] Phase currents i5 and i6 charge the second capacitor C2 through different paths. While charging, the second capacitor C2 supplies power to the second power stage IPM2. Simultaneously, the first capacitor C1 discharges its stored charge to supply power to the first power stage IPM1, causing a voltage drop. Consequently, the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0094] (2) If the first capacitor C1 needs to be charged, the specific process can be performed as described below. Figure 8 Schematic diagram of the current path for charging the first capacitor when the three-phase alternating current is in the second phase sector of the present utility model. Figure 8 As shown, the control circuit 25 controls the second switch unit K2 and the third switch unit K3 to turn on, and the first switch unit K1 to turn off. At this time, the voltage Va at the first input terminal a is higher than the voltage Vb at the second input terminal b. The corresponding phase current i7 (represented in red in the figure) flows from the first input inductor L1 through the diode D1, the first capacitor C1, and then through the intermediate voltage node v0, the second switch unit K2 to the second input terminal b, and then flows out through the second input inductor L2. At the same time, the voltage Va at the first input terminal a is higher than the voltage Vc at the third input terminal c. The corresponding phase current i8 (the path is represented in blue in the figure) flows from the first input inductor L1 through the diode D1, the first capacitor C1, and then through the intermediate voltage node v0, the third switch unit K3 to the third input terminal c, and then flows out through the third input inductor L3.

[0095] Phase currents i7 and i8 charge the first capacitor C1 through different paths. While charging, the first capacitor C1 supplies power to the first power stage IPM1. Simultaneously, the second capacitor C2 discharges its stored charge to supply power to the second power stage IPM2. This causes a voltage drop, and the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0096] Third phase sector

[0097] When the three-phase AC power at the input port is in the third phase sector (that is, the phase voltage state is 110):

[0098] (1) If the second capacitor C2 needs to be charged, the specific process can be performed as described below. Figure 9 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the third phase sector according to the embodiment of the present invention. Figure 9As shown, the control circuit 25 turns on the first switch unit K1, turns on the second switch unit K2, and turns off the third switch unit K3. The voltage Va at the first input terminal a is higher than the voltage Vc at the third input terminal c. The corresponding phase current i9 (the path is indicated in red in the figure) flows from the first input inductor L1 through the first switch unit K1, then through the intermediate voltage node v0, the second capacitor C2, and the diode D6, and then out of the node c through the third input inductor L3. Because the voltage Vb at the second input terminal b is higher than the voltage Vc at the third input terminal c, the phase current i10 (the path is indicated in blue in the figure) flows from the second input inductor L2 through the second switch unit K2, then through the intermediate voltage node v0, the second capacitor C2, the diode D6, and out of the node c through the third input inductor L3. This phase current also charges the second capacitor C2.

[0099] Phase currents i9 and i10 charge the second capacitor C2. While charging, the second capacitor C2 supplies power to the second power stage IPM2. Simultaneously, the first capacitor C1 discharges its stored charge to supply power to the first power stage IPM1, causing a voltage drop. Consequently, the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0100] (2) If the first capacitor C1 needs to be charged, the specific process can be performed as described below. Figure 10 Schematic diagram of the current path for charging the first capacitor when the three-phase AC power is in the third phase sector of the embodiment of the present invention. Figure 10 As shown, the control circuit 25 controls the third switch unit K3 to turn on, while the first and second switch units K1 and K2 are turned off. At this point, the voltage Va at the first input terminal a is higher than the voltage Vc at the third input terminal c. The corresponding phase current i11 (indicated in red in the figure) flows from the first input inductor L1 through the diode D1, the first capacitor C1, and then through the intermediate voltage node v0, reaching the third input terminal c through the third switch unit K3, and then flows out through the third input inductor L3. Simultaneously, the voltage Vb at the second input terminal b is higher than the voltage Vc at the third input terminal c. The corresponding phase current i12 (the path indicated in blue in the figure) flows from the second input inductor L2 through the diode D2, the first capacitor C1, and then through the intermediate voltage node v0, reaching the third input terminal c through the third switch unit K3, and then flows out through the third input inductor L3.

[0101] Phase currents i11 and i12 charge the first capacitor C1 through different paths. While charging, the first capacitor C1 supplies power to the first power stage IPM1. Simultaneously, the second capacitor C2 discharges its stored charge to supply power to the second power stage IPM2. This causes a voltage drop, and the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0102] Fourth phase sector

[0103] When the three-phase AC power at the input port is in the fourth phase sector (that is, the phase voltage state is 010):

[0104] (1) If the second capacitor C2 needs to be charged, the specific process can be performed as described below. Figure 11 Schematic diagram of the current path for charging the second capacitor when the three-phase AC power is in the fourth phase sector according to the embodiment of the present invention. Figure 11 As shown, the control circuit 25 controls the second switch unit K2 to turn on, while the first and third switch units K1 and K3 are turned off. The voltage Vb at the second input terminal b is higher than the voltage Va at the first input terminal a. The corresponding phase current i13 (the path is indicated in red in the figure) flows from the second input inductor L2 through the second switch unit K2, then through the intermediate voltage node v0, the second capacitor C2, and the diode D4, and then from node a through the first input inductor L1. At the same time, the voltage Vb at the second input terminal b is higher than the voltage Vc at the third input terminal c. The corresponding phase current i14 (the path is indicated in blue in the figure) flows from the second input inductor L2 through the second switch unit K2, then through the intermediate voltage node v0, the second capacitor C2, the diode D6, and then from node c through the third input inductor L3.

[0105] Phase currents i13 and i14 charge the second capacitor C2 through different paths. While charging, the second capacitor C2 supplies power to the second power stage IPM2. Simultaneously, the first capacitor C1 discharges its stored charge to supply power to the first power stage IPM1, causing a voltage drop. Consequently, the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0106] (2) If the first capacitor C1 needs to be charged, the specific process can be performed as described below. Figure 12 Schematic diagram of the current path for charging the first capacitor when the three-phase alternating current is in the fourth phase sector of the present utility model. Figure 12As shown, the control circuit 25 controls the first switch unit K1 to turn on, the second switch unit K2 to turn off, and the third switch unit K3 to turn on. At this time, the voltage Vb at the second input terminal b is higher than the voltage Va at the first input terminal a. The corresponding phase current i15 (represented in red in the figure) flows from the second input inductor L2 through the diode D2, the first capacitor C1, and then through the intermediate voltage node v0. The first switch unit K1 reaches the first input terminal a and then flows out through the first input inductor L1. Because the voltage Vb at the second input terminal b is higher than the voltage Vc at the third input terminal c, the phase current i16 (represented in blue in the figure) flows from the second input inductor L2 through the diode D2, the first capacitor C1, and then through the intermediate voltage node v0. The third switch unit K3 flows from node c and then out through the third input inductor L3. The phase current in this path can also charge the first capacitor C1.

[0107] Phase currents i15 and i16 charge the first capacitor C1. While charging, the first capacitor C1 supplies power to the first power stage IPM1. Simultaneously, the second capacitor C2 discharges its stored charge to supply power to the second power stage IPM2. This causes a voltage drop, and the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0108] Fifth phase sector

[0109] When the three-phase AC power at the input port is in the fifth phase sector (that is, the phase voltage state is 011):

[0110] (1) If the second capacitor C2 needs to be charged, the specific process can be performed as described below. Figure 13 Schematic diagram of the current path for charging the second capacitor when the three-phase alternating current is in the fifth phase sector of the present utility model embodiment. Figure 13 As shown, the control circuit 25 controls the second switch unit K2 to turn on, the first switch unit K1 to turn off, and the third switch unit K3 to turn on. The voltage Vb at the second input terminal b is higher than the voltage Va at the first input terminal a. The corresponding phase current i17 (the path is indicated in red in the figure) flows from the second input inductor L2 through the second switch unit K2, then through the intermediate voltage node v0, the second capacitor C2, and the diode D4, and then from node a through the first input inductor L1. Because the voltage Vb at the second input terminal b is higher than the voltage Vc at the third input terminal c, the phase current i18 (the path is indicated in blue in the figure) flows from the third input inductor L3 through the third switch unit K3, the intermediate voltage node v0, the second capacitor C2, and then through the diode D4 to node a. From node a, it flows out through the first input inductor L1. This phase current can also charge the second capacitor C2.

[0111] Phase currents i17 and i18 charge the second capacitor C2. While charging, the second capacitor C2 supplies power to the second power stage IPM2. Simultaneously, the first capacitor C1 discharges its stored charge to supply power to the first power stage IPM1, causing a voltage drop. Consequently, the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0112] (2) If the first capacitor C1 needs to be charged, the specific process can be performed as described below. Figure 14 Schematic diagram of the current path for charging the first capacitor when the three-phase AC power is in the fifth phase sector of the present utility model. Figure 14 As shown, the control circuit 25 controls the first switch unit K1 to turn on, while the second and third switch units K2 and K3 are turned off. At this point, the voltage Vb at the second input terminal b is higher than the voltage Va at the first input terminal a. The corresponding phase current i19 (indicated in red in the figure) flows from the second input inductor L2 through the diode D2, the first capacitor C1, and then through the intermediate voltage node v0. The first switch unit K1 reaches the first input terminal a and then flows out through the first input inductor L1. Simultaneously, the voltage Vc at the third input terminal c is higher than the voltage Va at the first input terminal a. The corresponding phase current i20 (indicated in blue in the figure) flows from the third input inductor L3 through the diode D3, the first capacitor C1, and then through the intermediate voltage node v0. The first switch unit K1 reaches the first input terminal a and then flows out through the first input inductor L1.

[0113] Phase currents i19 and i20 charge the first capacitor C1 through different paths. While charging, the first capacitor C1 supplies power to the first power stage IPM1. Simultaneously, the second capacitor C2 discharges its stored charge to supply power to the second power stage IPM2. This causes a voltage drop, and the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0114] Sixth phase sector

[0115] When the three-phase AC power at the input port is in the sixth phase sector (that is, the phase voltage state is 001):

[0116] (1) If the second capacitor C2 needs to be charged, the specific process can be performed as described below. Figure 15 Schematic diagram of the current path for charging the second capacitor when the three-phase AC power is in the sixth phase sector according to the embodiment of the present invention. Figure 15As shown, the control circuit 25 controls the third switch unit K3 to be turned on, while the first and second switch units K1 and K2 are turned off. The voltage Vc at the third input terminal c is higher than the voltage Va at the first input terminal a. The corresponding phase current i21 (the path is indicated in red in the figure) flows from the third input inductor L3 through the third switch unit K3, then through the intermediate voltage node v0, the second capacitor C2, the diode D4, and then out through the first input inductor L1 from node a.

[0117] At the same time, the voltage Vc at the third input terminal c is also higher than the voltage Vb at the second input terminal b. The corresponding phase current i22 (the path is indicated by blue in the figure) flows from the third input inductor L3 through the third switch unit K3, then through the intermediate voltage node v0, the second capacitor C2 and the diode D5, and flows out from the node b through the second input inductor L2.

[0118] Phase currents i21 and i22 charge the second capacitor C2 through different paths. While charging, the second capacitor C2 supplies power to the second power stage IPM2. Simultaneously, the first capacitor C1 discharges its stored charge to supply power to the first power stage IPM1, causing a voltage drop. Consequently, the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0119] (2) If the first capacitor C1 needs to be charged, the specific process can be performed as described below. Figure 16 Schematic diagram of the current path for charging the first capacitor when the three-phase AC power is in the sixth phase sector of the present utility model. Figure 16 As shown, the control circuit 25 controls the first switch unit K1 to be on, the second switch unit K2 to be on, and the third switch unit K3 to be off. At this time, the voltage Vc at the third input terminal c is higher than the voltage Va at the first input terminal a. The corresponding phase current i23 (indicated in red in the figure) flows from the third input inductor L3 through the diode D3, the first capacitor C1, and then through the intermediate voltage node v0. The first switch unit K1 reaches the first input terminal a and then flows out through the first input inductor L1. Because the voltage Vc at the third input terminal c is higher than the voltage Vb at the second input terminal b, the phase current i24 flows from the third input inductor L3 through the diode D3, the first capacitor C1, and then through the intermediate voltage node v0. The second switch unit K2 reaches the second input terminal b and then flows out through the second input inductor L2.

[0120] Phase currents i23 and i24 charge the first capacitor C1. While charging, the first capacitor C1 supplies power to the first power stage IPM1. Simultaneously, the second capacitor C2 discharges its stored charge to supply power to the second power stage IPM2. This causes a voltage drop, and the voltages of the first and second capacitors C1 and C2 move toward a balance point.

[0121] Table 1 shows the switch control logic for charging the first capacitor C1 or the second capacitor C2 in different phase sectors. According to the control logic in Table 1, the control circuit 25 can switch the state of the switch unit to charge either capacitor when the voltage of either capacitor is low, so that the input voltage of the first power stage IPM1 and the second power stage IPM2 remains stable at approximately half of the peak value of the DC voltage output of the three-phase rectifier circuit, approximately 40% to 60% of the peak value of the DC voltage output of the three-phase rectifier circuit, and preferably maintains the input voltage of the first power stage IPM1 and the second power stage IPM2 at half of the peak value of the DC voltage output of the three-phase rectifier circuit.

[0122] Table 1

[0123]

[0124] The above describes the corresponding switch unit control mode for charging the first capacitor C1 or the second capacitor C2 in each phase sector. It should be understood that in some embodiments, as soon as the AC load driving device 2 is triggered to charge, it immediately selects the corresponding control mode based on the phase sector of the currently input three-phase AC power to control the first switch unit K1, the second switch unit K2, and the third switch unit K3 in the voltage divider circuit 23 to charge the first capacitor C1 or the second capacitor C2, thereby achieving operation in all six phase sectors.

[0125] In other embodiments, the device is not required to have the ability to balance voltages in all six phase sectors. That is, after being triggered to charge, the AC load driving device 2 will wait for a phase sector in which it can work, and control the first switch unit K1, the second switch unit K2, and the third switch unit K3 in the voltage divider circuit 23 to charge the first capacitor C1 or the second capacitor C2 according to the mode of the sector. For example, the AC load driving device 2 can switch states for charging only in the first phase sector and the fourth phase sector. For another example, the AC load driving device 2 can charge the first capacitor C1 only in the first phase sector and charge the second capacitor C2 only in the third phase sector. That is to say, for the control circuit of the embodiment of the utility model, it may only have the ability to control the voltage divider circuit in some, but not all, of the six sectors, which can reduce the high requirements for the response speed and specifications of the control circuit, further reducing costs.

[0126] Therefore, the embodiment of the present invention sets a voltage divider circuit between the input end and the intermediate voltage node of the three-phase rectifier bridge, and connects two capacitors between the intermediate voltage node and the two output ends of the three-phase rectifier circuit respectively, so that the voltage divider circuit controls the on and off between different output ends and the intermediate voltage node, thereby maintaining the voltage balance of the two capacitors. Furthermore, by connecting two power stages in parallel with the two capacitors respectively, one power stage uses the intermediate voltage node as the control ground node, and the other power stage uses the reference ground of the three-phase rectifier circuit as the control ground node, so that the maximum operating voltage of the two power stages can be only half of the voltage peak output by the three-phase rectifier bridge, effectively reducing the requirements for the operating voltage specifications of the power stage circuit and the subsequently connected AC load, reducing the cost of electrical equipment, and improving safety to a certain extent.

[0127] The foregoing is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any equivalent modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An AC load driving device, characterized in that: The AC load driving device comprises: A three-phase rectifier circuit having three input inductors and a three-phase rectifier bridge, wherein the three-phase rectifier bridge has a first input terminal, a second input terminal, a third input terminal, a first output terminal, and a second output terminal, wherein the three input inductors are respectively connected between each input terminal of the three-phase alternating current power and the first input terminal, the second input terminal, and the third input terminal, and the three-phase rectifier bridge is used to output a DC voltage from the first output terminal and the second output terminal; A voltage divider circuit is connected to each input terminal of the three-phase rectifier bridge, and an output terminal of the voltage divider circuit is connected to an intermediate voltage node; a first capacitor connected between the first output terminal and the intermediate voltage node; a second capacitor connected between the second output terminal and the intermediate voltage node; A first power stage is connected in parallel with the first capacitor, uses the intermediate voltage node as a control ground node, and is used to input a voltage across the first capacitor to drive a first AC load; The second power stage is connected in parallel with the second capacitor, takes the second output end as a control ground node, and is used to input a voltage across the second capacitor to drive a second AC load.

2. The AC load driving device according to claim 1, characterized in that: The voltage divider circuit comprises: a first switch unit, connected between the first input terminal of the three-phase rectifier bridge and the intermediate voltage node; a second switch unit connected between the second input terminal of the three-phase rectifier bridge and the intermediate voltage node; and The third switch unit is connected between the third input terminal of the three-phase rectifier bridge and the intermediate voltage node.

3. The AC load driving device according to claim 1, characterized in that: The peak value of the input voltage of the first power stage is 40% to 60% of the peak value of the voltage output by the three-phase rectifier bridge, and the peak value of the input voltage of the second power stage is 40% to 60% of the peak value of the voltage output by the three-phase rectifier bridge.

4. The AC load driving device according to claim 1 or 3, characterized in that: The peak value of the input voltage of the first power stage is half of the peak value of the voltage output by the three-phase rectifier bridge; the peak value of the input voltage of the second power stage is half of the peak value of the voltage output by the three-phase rectifier bridge.

5. The AC load driving device according to claim 2, characterized in that: The AC load driving device further includes: a detection circuit, configured to detect a voltage across the first capacitor and output a first detection voltage, and to detect a voltage across the second capacitor and output a second detection voltage; The control circuit controls the voltage divider circuit to charge the first capacitor or the second capacitor according to the first detection voltage and the second detection voltage.

6. The AC load driving device according to claim 5, characterized in that: The control circuit is configured to control the voltage divider circuit to charge the second capacitor when the voltage across the first capacitor is higher than the voltage across the second capacitor, and to control the voltage divider circuit to charge the first capacitor when the voltage across the second capacitor is higher than the voltage across the first capacitor.

7. The AC load driving device according to claim 5, characterized in that: The control circuit is configured to control the voltage divider circuit to charge the first capacitor when the voltage across the first capacitor is lower than a predetermined threshold voltage, and to control the voltage divider circuit to charge the second capacitor when the voltage across the second capacitor is lower than the predetermined threshold voltage.

8. The AC load driving device according to claim 5, characterized in that: The control circuit is configured to control the first switch unit, the second switch unit and a part of the third switch unit to be turned on or off according to the different phase sectors of the three-phase alternating current to charge the first capacitor or the second capacitor, and the voltage divider circuit is configured to control the voltage across the first capacitor and the second capacitor to remain balanced.

9. The AC load driving device according to claim 8, characterized in that: The control circuit is configured to control the first switch unit and the third switch unit to be turned on and the second switch unit to be turned off in a first phase sector to charge the second capacitor, or to control the first switch unit and the third switch unit to be turned off and the second switch unit to be turned on in the first phase sector to charge the first capacitor; The first phase sector is a phase sector in which the phase voltage corresponding to the first input terminal is positive, the phase voltage corresponding to the second input terminal is negative, and the phase voltage corresponding to the third input terminal is positive in the three-phase alternating current.

10. The AC load driving device according to claim 8, characterized in that: The control circuit is configured to control the first switch unit to be turned on and the second switch unit and the third switch unit to be turned off in the second phase sector to charge the second capacitor, or to control the second switch unit and the third switch unit to be turned on and the first switch unit to be turned off in the second phase sector to charge the first capacitor; The second phase sector is a phase sector in which the phase voltage corresponding to the first input end is positive, the phase voltage corresponding to the second input end is negative, and the phase voltage corresponding to the third input end is negative in the three-phase alternating current.

11. The AC load driving device according to claim 8, characterized in that: The control circuit is configured to control the first switch to be turned on, the second switch unit to be turned on, and the third switch unit to be turned off in a third phase sector to charge the second capacitor; or, In a third phase sector, the third switch is controlled to be turned on, and the first switch and the second switch are controlled to be turned off to charge the first capacitor; The third phase sector is a phase sector in which the phase voltage corresponding to the first input end is positive, the phase voltage corresponding to the second input end is positive, and the phase voltage corresponding to the third input end is negative in the three-phase alternating current.

12. The AC load driving device according to claim 8, characterized in that: The control circuit is configured to control the second switch unit to be turned on and the first switch unit and the third switch unit to be turned off in a fourth phase sector to charge the second capacitor; or, In a fourth phase sector, controlling the first switch unit to be turned on, the second switch to be turned off, and the third switch to be turned on to charge the first capacitor; The fourth phase sector is a phase sector in which the phase voltage corresponding to the first input end is negative, the phase voltage corresponding to the second input end is positive, and the phase voltage corresponding to the third input end is negative in the three-phase alternating current.

13. The AC load driving device according to claim 8, characterized in that: The control circuit is configured to control the second switch unit to be turned on, the first switch unit to be turned off, and the third switch unit to be turned on in the fifth phase sector to charge the second capacitor; or, In a fifth phase sector, controlling the first switch unit to be turned on, and the second switch unit and the third switch unit to be turned off to charge the first capacitor; The fifth phase sector is a phase sector in which the phase voltage corresponding to the first input end is negative, the phase voltage corresponding to the second input end is positive, and the phase voltage corresponding to the third input end is positive in the three-phase alternating current.

14. The AC load driving device according to claim 8, characterized in that: The control circuit is configured to control the third switch unit to be turned on and the first switch unit and the second switch unit to be turned off in the sixth phase sector to charge the second capacitor; or, In a sixth phase sector, the third switch unit is controlled to be turned off, and the first switch unit and the second switch unit are controlled to be turned on, so as to charge the first capacitor; The sixth phase sector is a phase sector in which the phase voltage corresponding to the first input end is negative, the phase voltage corresponding to the second input end is negative, and the phase voltage corresponding to the third input end is positive in the three-phase alternating current.

15. The AC load driving device according to claim 1, characterized in that: The three-phase alternating current is a three-phase alternating current with an effective value of 380V, and the operating voltage specifications of the first power level and the second power level are not less than 600V.

16. The AC load driving device according to claim 1, characterized in that: The first power stage is a first power module, and the second power stage is a second power module.

17. The AC load driving device according to claim 5, characterized in that: The first capacitor is charged while also supplying power to the first power stage, and the second capacitor is charged while also supplying power to the second power stage.

18. The AC load driving device according to any one of claims 9 to 14, characterized in that: When the first capacitor is not charged, the first capacitor is discharged to supply power to the first power stage; when the second capacitor is not charged, the second capacitor is discharged to supply power to the second power stage.

19. An electrical device, characterized in that: The electrical equipment includes: The AC load driving device according to any one of claims 1 to 18; a first AC load connected to the first power stage of the AC load driving device; The second AC load is connected to the second power stage of the AC load driving device.

20. The electrical device according to claim 19, characterized in that The electrical equipment is an air conditioner, and the first AC load and the second AC load are air conditioner compressors or fan motors.

Images