Power conversion circuit, power conversion device and energy storage device

Abstract

The utility model provides a power conversion circuit, a power conversion device and an energy storage device. The power conversion circuit comprises three switch tube modules and three energy storage inductors, in each switch tube module, two ends of a first bridge arm, two ends of a second bridge arm and two ends of an output capacitor are connected in parallel between positive and negative DC buses, the first bridge arm comprises a first upper switch tube and a first lower switch tube which are connected, and the second bridge arm comprises a second upper switch tube and a second lower switch tube which are connected. The second bridge arm comprises a second upper switch tube and a second lower switch tube which are connected. The midpoint of the first bridge arm in each switch tube module is connected with the midpoint of the second bridge arm in another switch tube module through one energy storage inductor, and the midpoint of the second bridge arm in each switch tube module is connected with the midpoint of the first bridge arm in the rest switch tube module through another energy storage inductor. And the negative direct current buses in the three switch tube modules are connected with three phase lines of the alternating current power supply in a one-to-one correspondence manner. According to the power conversion circuit, common-mode noise interference can be effectively suppressed under the condition that a filter circuit and an auxiliary circuit are not additionally arranged.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and particularly to a power conversion circuit, a power conversion device, and an energy storage device. Background Art

[0002] Power Factor Correction (PFC) circuits have been widely used because they can suppress the pollution of harmonics to the power grid, reduce reactive power, and improve the power factor. However, the current three-phase PFC circuits have serious common-mode noise interference problems, and additional filter circuits or auxiliary circuits need to be added to improve the noise interference, which will lead to a decrease in power density and an increase in cost. Summary of the Utility Model

[0003] To solve the deficiencies of the prior art, this application provides a power conversion circuit, a power conversion device, and an energy storage device.

[0004] In the first aspect of this application, a power conversion circuit is provided. The power conversion circuit includes: three switch tube modules and three energy storage inductors; each switch tube module includes a first bridge arm, a second bridge arm, an output capacitor, a positive DC bus, and a negative DC bus, and both ends of the first bridge arm, the second bridge arm, and the output capacitor are connected in parallel between the positive DC bus and the negative DC bus; the first bridge arm includes a first upper switch tube and a first lower switch tube connected in series, and the second bridge arm includes a second upper switch tube and a second lower switch tube connected in series; the midpoint of the first bridge arm in each switch tube module is connected to the midpoint of the second bridge arm in another switch tube module through an energy storage inductor, and the midpoint of the second bridge arm in each switch tube module is connected to the midpoint of the first bridge arm in the remaining one switch tube module through another energy storage inductor; the negative DC buses in the three switch tube modules are respectively connected to the three-phase lines of the AC power supply in one-to-one correspondence, and the three switch tube modules are respectively used to access the corresponding phase of the AC power supply and output direct current through the output capacitor.

[0005] In one embodiment, both the first upper switch tube and the second upper switch tube are diodes, and both the first lower switch tube and the second lower switch tube are power switch tubes. Among them, the first upper switch tube and the first lower switch tube in the same first bridge arm are reversely connected in series, and the second upper switch tube and the second lower switch tube in the same second bridge arm are reversely connected in series.

[0006] In one embodiment, a first bridge arm and a second bridge arm connected to the same energy storage inductor form a set of bridge arms, and a corresponding line voltage is formed between the first bridge arm and the second bridge arm of the same set; in the positive half cycle of the line voltage corresponding to the bridge arms of the same set, the first lower switch tube in the first bridge arm of the same set is constantly conducting, and the second lower switch tube in the second bridge arm of the same set is switched on and off at a high frequency; in the negative half cycle of the line voltage corresponding to the bridge arms of the same set, the first lower switch tube in the first bridge arm of the same set is switched on and off at a high frequency, and the second lower switch tube in the second bridge arm of the same set is constantly conducting.

[0007] In one embodiment, the first upper switch tube, the second upper switch tube, the first lower switch tube, and the second lower switch tube are all power switch tubes. Among them, the first upper switch tube and the first lower switch tube in the same first bridge arm are connected in series, and the second upper switch tube and the second lower switch tube in the same second bridge arm are connected in series.

[0008] In one embodiment, a first bridge arm and a second bridge arm connected to the same energy storage inductor form a set of bridge arms, and a corresponding line voltage is formed between the first bridge arm and the second bridge arm of the same set; in the positive half cycle of the line voltage corresponding to the bridge arms of the same set, it is controlled that the first lower switch tube in the first bridge arm of the same set is constantly conducting and the first upper switch tube is constantly turned off, the second lower switch tube in the second bridge arm of the same set is switched on and off at a high frequency, and the second upper switch tube and the second lower switch tube are complementary in conduction; and, in the negative half cycle of the line voltage corresponding to the bridge arms of the same set, it is controlled that the first lower switch tube in the first bridge arm of the same set is switched on and off at a high frequency, and the first upper switch tube and the first lower switch tube are complementary in conduction, the second lower switch tube in the second bridge arm of the same set is constantly conducting and the second upper switch tube is constantly turned off.

[0009] In one embodiment, the power switch tube includes at least one of a metal oxide semiconductor field effect transistor, an insulated gate bipolar transistor, and a gallium nitride high electron mobility transistor.

[0010] In one embodiment, the diode includes at least one of an ultrafast recovery diode and a silicon carbide Schottky diode.

[0011] In the second aspect of the present application, a power conversion device is provided. The power conversion device includes a power conversion circuit and a controller. The power conversion circuit includes three switching tube modules and three energy storage inductors. Each switching tube module includes a first arm, a second arm, an output capacitor, a positive DC bus, and a negative DC bus. The two ends of the first arm, the second arm, and the output capacitor are all connected in parallel between the positive DC bus and the negative DC bus. The first arm includes a connected first upper switching tube and a first lower switching tube, and the second arm includes a connected second upper switching tube and a second lower switching tube. The midpoint of the first arm in each switching tube module is connected to the midpoint of the second arm in another switching tube module through an energy storage inductor, and the midpoint of the second arm in each switching tube module is connected to the midpoint of the first arm in the remaining switching tube module through another energy storage inductor. The negative DC buses in the three switching tube modules are connected to the three-phase lines of the AC power supply in one-to-one correspondence. The three switching tube modules are also connected to the controller, and the controller outputs a control signal to the three switching tube modules. The control signal is used to control the three switching tube modules to jointly convert the three-phase alternating current connected to the AC power supply into direct current.

[0012] In one embodiment, the controller outputs a first control signal to the first arm in the three switching tube modules and outputs a second control signal to the second arm in the three switching tube modules. The first control signal is used to control the on-off state of the switching tubes in the first arm, and the second control signal is used to control the on-off state of the switching tubes in the second arm.

[0013] In the third aspect of the present application, an energy storage device is provided. The energy storage device includes a power conversion circuit, a DC conversion circuit, and a battery pack. The power conversion circuit is connected to the battery pack through the DC conversion circuit, where the power conversion circuit is the power conversion circuit described in the first aspect or any one of the embodiments in the first aspect.

[0014] Compared with the prior art, the present application has at least the following advantages:

[0015] 1. By designing the structure of the three switching tube modules, the connection relationship between the three switching tube modules and the three energy storage inductors, and the connection relationship between the three switching tube modules and the AC power supply, the power conversion circuit of the present application can be used to convert the input three-phase alternating current into direct current and can also be used to achieve multi-port output.

[0016] 2. By connecting the negative DC bus of the switching tube module to the phase line of the AC power supply, the input and output ends of the power conversion circuit are connected in a common-ground manner, thereby suppressing common-mode noise interference and reducing circulating current at the source. Therefore, the common-mode noise is effectively improved, and the power conversion circuit does not need to additionally provide a filter circuit and an auxiliary circuit, avoiding the decrease in power density and the increase in cost of the power conversion circuit.

[0017] 3. In the power conversion circuit of the present application, the inductor current of the energy storage inductor connected to the same group of bridge arms can track the change of the line voltage of the same group of bridge arms. The waveforms of the inductor current and the line voltage can both achieve good sinusoidality without distortion. Therefore, power factor correction can be realized.

[0018] 4. The power conversion circuit of the present application can design the first bridge arm and the second bridge arm according to actual situations. For example, it can be designed that both the first bridge arm and the second bridge arm are composed of a diode and a power switch tube, or it can be designed that both the first bridge arm and the second bridge arm are composed of two power switch tubes. Therefore, the design flexibility is high.

[0019] 5. In the power conversion circuit of the present application, each switching tube module and the energy storage inductor connected thereto can form a standard bridgeless PFC circuit. Currently, the standard bridgeless PFC is basically only applied to the single-phase field and there are also serious problems of common-mode noise interference. By improving the connection relationship of the standard bridgeless PFC circuit, the present application can realize the application of the standard bridgeless PFC circuit in the three-phase field, broaden the application field of the standard bridgeless PFC, and the common-mode noise interference of the circuit is small. Therefore, the power conversion circuit of the present application has the advantages of low common-mode noise, simple structure, low cost, small volume, and high power density.

[0020] 6. In the power conversion circuit of the present application, both the first bridge arm and the second bridge arm in the switching tube module can be composed of a diode and a power switch tube. Compared with the upper and lower power switch tubes connected in series, which usually need to consider dead time and prevent bridge arm shoot-through, the power conversion circuit of the present application does not need to involve dead time control, and there is no problem of bridge arm shoot-through short circuit. Therefore, the control complexity is lower, the use reliability is higher, and the circuit cost is also lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic connection diagram of a power conversion circuit provided by an embodiment of the present application.

[0022] Figure 2 is a circuit diagram of a power conversion circuit provided by Embodiment 1.

[0023] Figure 3 is Figure 2 a signal waveform diagram of the power conversion circuit shown.

[0024] Figure 4 is a circuit diagram of a power conversion circuit provided by Embodiment 2.

[0025] Figure 5 is a schematic diagram of a power conversion device provided by an embodiment of the present application.

[0026] Figure 6 is a schematic diagram of an energy storage device provided by an embodiment of the present application.

[0027] Description of Main Component Symbols

[0028] Power Conversion Circuit 100

[0029] Switching Tube Modules 101, 102, 103

[0030] First Arm 104

[0031] Second Arm 105

[0032] AC Power Supply 200

[0033] Load 300

[0034] Controller 400

[0035] DC Conversion Circuit 500

[0036] Battery Pack 600

[0037] Power Conversion Device 1000

[0038] Energy Storage Device 2000 Detailed Implementation Manner

[0039] In order to enable those skilled in the art of the present technology to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present application. Without conflict, the following different embodiments and the features in the embodiments can be combined with each other.

[0040] Please refer to Figure 1 , which shows a connection schematic diagram of the power conversion circuit 100 provided in the embodiment of the present application.

[0041] As Figure 1 shown, the power conversion circuit 100 is connected to the AC power supply 200 and the load 300. The power conversion circuit 100 can be used to convert the three-phase alternating current provided by the AC power supply 200 into direct current and then supply power to the load 300.

[0042] It should be understood that the power conversion circuit 100 can be applied to fields such as energy storage power supplies, data centers, charging stations, automobiles, and base stations. The AC power supply 200 can be a power grid or other power supplies that can provide three-phase AC power of A, B, and C. The voltages of the three-phase AC power are Va, Vb, and Vc respectively, and the currents are Ia, Ib, and Ic respectively. The load 300 can be a battery pack, a subsequent DC conversion circuit, or any electronic device that can consume DC power, etc. Specifically, it can be selected accordingly according to the application scenario of the power conversion circuit 100, and no specific limitation is made here.

[0043] For better understanding, the power conversion circuit 100 provided by the embodiments of the present application will be introduced in detail below in combination with Embodiment 1 and Embodiment 2.

[0044] Please refer to Figure 2 , which is the circuit diagram of the power conversion circuit 100 provided for Embodiment 1. As Figure 2 shown, the power conversion circuit 100 includes three switch tube modules 101, 102, 103 and three energy storage inductors L1, L2, L3.

[0045] Specifically, the switch tube module 101 includes a first bridge arm 104, a second bridge arm 105, an output capacitor C1, a positive DC bus BUS1+ and a negative DC bus BUS1-. The first bridge arm 104 includes a first upper switch tube D1a and a first lower switch tube Q1a, and the second bridge arm 105 includes a second upper switch tube D2a and a second lower switch tube Q2a.

[0046] The switch tube module 102 includes a first bridge arm 104, a second bridge arm 105, an output capacitor C2, a positive DC bus BUS2+ and a negative DC bus BUS2-. The first bridge arm 104 includes a first upper switch tube D1b and a first lower switch tube Q1b, and the second bridge arm 105 includes a second upper switch tube D2b and a second lower switch tube Q2b.

[0047] The switch tube module 103 includes a first bridge arm 104, a second bridge arm 105, an output capacitor C3, a positive DC bus BUS3+ and a negative DC bus BUS3-. The first bridge arm 104 includes a first upper switch tube D1c and a first lower switch tube Q1c, and the second bridge arm 105 includes a second upper switch tube D2c and a second lower switch tube Q2c.

[0048] Each of the above-mentioned first lower switching transistors and each second lower switching transistor is a power switching transistor, and each first upper switching transistor and each second upper switching transistor is a diode. Among them, the power switching transistor includes, but is not limited to, at least one of a metal oxide semiconductor field effect transistor (MOSFET, such as SiMOSFET, SiC MOSFET), an insulated gate bipolar transistor (IGBT), and a gallium nitride high electron mobility transistor (GaN HEMT). For convenience of description, Figure 2 the first lower switching transistor and the second lower switching transistor in

[0049] are shown by taking the MOSFET as an example. The drain of the MOSFET is the first connection end, the source is the second connection end, and the gate is the control end. The diode is a high-voltage diode, including, but not limited to, at least one of an ultrafast recovery diode and a silicon carbide Schottky diode.

[0050] In the switching transistor module 102, both ends of the first arm 104, the second arm 105, and the output capacitor C2 are connected in parallel between the positive DC bus BUS2+ and the negative DC bus BUS2-. The first lower switching transistor Q1b and the first upper switching transistor D1b in the same first arm 104 are connected in reverse series. The second lower switching transistor Q2b and the second upper switching transistor D2b in the same second arm 105 are connected in reverse series. In the switching transistor module 103, both ends of the first arm 104, the second arm 105, and the output capacitor C3 are connected in parallel between the positive DC bus BUS3+ and the negative DC bus BUS3-. The first lower switching transistor Q1c and the first upper switching transistor D1c in the same first arm 104 are connected in reverse series. The second lower switching transistor Q2c and the second upper switching transistor D2c in the same second arm 105 are connected in reverse series. For the specific connection conditions of the first arm 104, the second arm 105, and the positive and negative DC buses in the switching transistor modules 102 and 103, reference can be made to the switching transistor module 101, which will not be elaborated here.

[0051] In the embodiment of the present application, the midpoint of the first arm in each switching transistor module is connected to the midpoint of the second arm in another switching transistor module through an energy storage inductor. The midpoint of the second arm in each switching transistor module is connected to the midpoint of the first arm in the remaining switching transistor module through another energy storage inductor, so that any two of the three switching transistor modules are connected through the corresponding energy storage inductors.

[0052] Specifically, in one embodiment, as Figure 3 shown, the midpoint of the first arm 104 of the switching transistor module 101 is connected to the midpoint of the second arm 105 of the switching transistor module 102 through the energy storage inductor L1. The midpoint of the first arm 104 of the switching transistor module 102 is connected to the midpoint of the second arm 105 of the switching transistor module 103 through the energy storage inductor L2. The midpoint of the first arm 104 of the switching transistor module 103 is connected to the midpoint of the second arm 105 of the switching transistor module 101 through the energy storage inductor L3. In the present application, for the convenience of description, the first arm 104 and the second arm 105 connected to the same energy storage inductor can be referred to as a group of arms.

[0053] In another embodiment, the midpoint of the first arm 104 of the switching transistor module 101 is connected to the midpoint of the second arm 105 of the switching transistor module 103 through the energy storage inductor L1. The midpoint of the first arm 104 of the switching transistor module 103 is connected to the midpoint of the second arm 105 of the switching transistor module 102 through the energy storage inductor L3. The midpoint of the first arm 104 of the switching transistor module 102 is connected to the midpoint of the second arm 105 of the switching transistor module 101 through the energy storage inductor L2. It can be understood that the working principles of these two embodiments are the same. For the convenience of description, the present application takes Figure 3Taking the circuit shown as an example for illustration, the relevant descriptions of another embodiment can be referred to Figure 3 the embodiment shown. This application will not repeat the introduction.

[0054] Based on such a design, the switching transistor modules 101, 102, and 103 are all bridge-less circuit topologies. Each switching transistor module and the two energy storage inductors connected thereto can jointly form a standard bridge-less PFC circuit. Therefore, the structural topology of the entire power conversion circuit 100 is approximately three standard bridge-less PFC circuits sharing three energy storage inductors.

[0055] Moreover, the negative DC buses in the three switching transistor modules are respectively connected to the three-phase phase lines of the AC power supply 200 in one-to-one correspondence. For the convenience of description, Figure 2 taking the negative DC bus BUS1- connected to the A-phase line of the AC power supply 200, the negative DC bus BUS2- connected to the B-phase line of the AC power supply 200, and the negative DC bus BUS3- connected to the C-phase line of the AC power supply 200 as an example for display. Therefore, the switching transistor module 101 can access the A-phase alternating current of the AC power supply 200 through the negative AC bus BUS1-, the switching transistor module 102 can access the B-phase alternating current of the AC power supply 200 through the negative AC bus BUS2-, and the switching transistor module 103 can access the C-phase alternating current of the AC power supply 200 through the negative AC bus BUS3-.

[0056] Correspondingly, when the circuit is connected, a corresponding line voltage can be generated between the first bridge arm 104 and the second bridge arm 105 connected to the same energy storage inductor. The first bridge arm 104 and the second bridge arm 105 connected to the same energy storage inductor can be called a group of bridge arms. For example, in Figure 2 the first bridge arm 104 (Q1a, D1a) and the second bridge arm 105 (Q2b, D2b) connected to the energy storage inductor L1 form a group of bridge arms and can form a line voltage Vmba. The first bridge arm 104 (Q1b, D1b) and the second bridge arm 105 (Q2c, D2c) connected to the energy storage inductor L2 form a group of bridge arms and can form a line voltage Vmcb. The first bridge arm 104 (Q1c, D1c) and the second bridge arm 105 (Q2a, D2a) connected to the energy storage inductor L3 form a group of bridge arms and can form a line voltage Vmac. The line voltages Vmba, Vmcb, and Vmac all change in a sine wave pattern, and there is a 120° phase difference between any two of them.

[0057] Moreover, an inductor current iL1 can flow through the energy storage inductor L1, an inductor current iL2 can flow through the energy storage inductor L2, and an inductor current iL3 can flow through the energy storage inductor L3. The inductor currents iL1, iL2, and iL3 are all line currents that change in a sine wave pattern, and there is a 120° phase difference between any two of them.

[0058] It should be understood that since the AC power supply 200 in Embodiment 1 is connected to the negative AC bus, the AC current of the AC power supply 200 first passes through the lower switching tube directly connected to the negative AC bus and then flows to the upper switching tube, and then can flow to the load 300. Therefore, the lower switching tubes in each arm can be regarded as auxiliary switching tubes, and the upper switching tubes in each arm can be regarded as main switching tubes.

[0059] The power conversion circuit 100 can be connected to a controller ( Figure 1 and Figure 2 not shown in the figure). The controller can be an MCU (Microcontroller Unit), or other general controllers or other circuits / modules / units / devices with control functions. The controller can output control signals to the first arm and the second arm of the three switching tube modules. Under the control of the control signals, the three switching tube modules jointly convert the three-phase alternating current connected to the AC power supply into direct current and output the direct current through the output capacitors, or in other words, cause a DC voltage to be generated across the output capacitors.

[0060] It can be understood that the output capacitors C1, C2, and C3 can be respectively connected to different loads 300 with the same power consumption requirements, or can be connected to the same load 300. After obtaining the direct current output by the output capacitors, the load 300 can be powered on to work. For the convenience of description, Figure 2 in the figure, it is shown by taking the output capacitor C1 connected to the load R1, the output capacitor C2 connected to the load R2, and the output capacitor C3 connected to the load R3 as an example. The output capacitor C1 can output a DC voltage Vo1 to the load R1, the output capacitor C2 can output a DC voltage Vo2 to the load R3, and the output capacitor C3 can output a DC voltage Vo3 to the load R3.

[0061] Next, in combination with Figure 3 the working principle of the power conversion circuit 100 in Embodiment 1 will be described.

[0062] Figure 3 FIG. shows the signal waveform diagram of the power conversion circuit 100 in Embodiment 1, where the data on the horizontal and vertical coordinates are only for illustration and do not constitute a limitation to the present application. Figure 3 The signals shown include: a preset carrier signal Vcar, line voltages Vmba, Vmcb, Vmac, inductor currents iL1, iL2, iL3, the first control signal S1a of the first lower switching tube Q1a, the second control signal S2b of the second lower switching tube Q2b, the first control signal S1b of the first lower switching tube Q1b, the second control signal S2c of the second lower switching tube Q2c, the first control signal S1c of the first lower switching tube Q1c, and the second control signal S2a of the second lower switching tube Q2a.

[0063] Among them, each line voltage corresponds to a first arm 104 and a second arm 105. Specifically, the line voltage Vmba can be the line voltage between the first arm 104 (Q1a, D1a) and the second arm 105 (Q2b, D2b) connected to the energy storage inductor L1, the line voltage Vmcb can be the line voltage between the first arm 104 (Q1b, D1b) and the second arm 105 (Q2c, D2c) connected to the energy storage inductor L2, and the line voltage Vmac can be the line voltage between the first arm 104 (Q1c, D1c) and the second arm 105 (Q2a, D2a) connected to the energy storage inductor L3.

[0064] The line voltage can be used as a modulation voltage signal, and the controller can generate a control signal according to the line voltage and a preset carrier signal. Since the line voltage corresponds to the first arm 104 and the second arm 105, accordingly, corresponding control signals can be accurately modulated according to each line voltage to control the corresponding set of arms. In this application, for the convenience of distinction, the control signal given to the first arm 104 is called the first control signal, and the control signal given to the second arm 105 is called the second control signal. The first control signal is used to control the on-off state of the switching tubes of the first arm 104, and the second control signal is used to control the on-off state of the switching tubes of the second arm 105.

[0065] Exemplarily, the controller can generate a first control signal S1a and a second control signal S2b according to the line voltage Vmba and the preset carrier signal Vcar. Among them, the first control signal S1a is used to control the on-off state of the first lower switching tube Q1a in the first arm 104 of the same group, and the second control signal S2b is used to control the on-off state of the second lower switching tube Q2b in the second arm 105 of the same group.

[0066] Similarly, the controller can generate a first control signal S1b and a second control signal S2c according to the line voltage Vmcb and the preset carrier signal Vcar. Among them, the first control signal S1b is used to control the on-off state of the first lower switching tube Q1b in the first arm 104 of the same group, and the second control signal S2c is used to control the on-off state of the second lower switching tube Q2c in the second arm 105 of the same group.

[0067] Similarly, the controller can generate a first control signal S1c and a second control signal S2a according to the line voltage Vmac and the preset carrier signal Vcar. Among them, the first control signal S1c is used to control the on-off state of the first lower switching tube Q1c in the first arm 104 of the same group, and the second control signal S2a is used to control the on-off state of the second lower switching tube Q2a in the second arm 105 of the same group.

[0068] In the first embodiment, the preset carrier signal Vcar can be, for example, a triangular wave signal or a sawtooth wave signal ( Figure 3The Vcar waveform distribution in the figure is dense, and the triangular or sawtooth shape is not shown in detail. Understandably, the line voltages Vmba, Vmcb, and Vmac can be modulated using the same preset carrier signal Vcar.

[0069] In the first embodiment, the line voltages Vmba, Vmcb, and Vmac are obtained by performing voltage-current loop calculations on the DC voltages Vo1, Vo2, Vo3 across the three output capacitors and the inductor currents iL1, iL2, iL3 of the three energy storage inductors. For example, the controller 400 can subtract the sum of the three DC voltages from the preset reference voltage to obtain a voltage difference, then perform deviation adjustment on the voltage difference to obtain a reference current. Also, the three inductor currents can be converted to the two-phase rotating coordinate system through ABC / dq conversion to obtain the active current component and the reactive current component. Then, the deviation between the reference current and the active DC component is adjusted to obtain the first voltage, and the deviation between 0 and the reactive current component is adjusted to obtain the second voltage. Then, the first voltage and the second voltage are converted to the three-phase stationary coordinate system through dq / ABC conversion to obtain the three line voltages Vmba, Vmcb, and Vmac. Alternatively, the line voltages Vmba, Vmcb, and Vmac can also be obtained through a signal measurement device or other means.

[0070] Specifically, as Figure 3 shown, the working process of the power conversion circuit 100 is as follows:

[0071] During the positive half-cycle of the line voltage Vmba, the first control signal S1a is a PWM signal ( Figure 3 the PWM waveform distribution in the figure is dense, so the high and low levels are not shown), so under the control of the first control signal S1a, the first lower switch Q1a in the first bridge arm 104 is switched on and off at a high frequency. The second control signal S2b is at a high level, so under the control of the second control signal S2b, the second lower switch Q2b in the second bridge arm 105 is constantly conducting.

[0072] During the negative half-cycle of the line voltage Vmba, the second control signal S2b is a PWM signal, so under the control of the second control signal S2b, the second lower switch Q2b in the second bridge arm 105 is switched on and off at a high frequency. The first control signal S1a is at a high level, so under the control of the first control signal S1a, the first lower switch Q1a in the first bridge arm 104 is constantly conducting.

[0073] Similarly, during the positive half-cycle of the line voltage Vmcb, under the control of the first control signal S1b, the first lower switch Q1b in the first bridge arm 104 is switched on and off at a high frequency, and under the control of the second control signal S2c, the second lower switch Q2c in the second bridge arm 105 is constantly conducting.

[0074] During the negative half - cycle of the line voltage Vmcb, under the control of the first control signal S1b, the first lower switch Q1b in the first arm 104 conducts constantly, and under the control of the second control signal S2c, the second lower switch Q2c in the second arm 105 conducts with high - frequency switching.

[0075] Similarly, during the positive half - cycle of the line voltage Vmac, under the control of the first control signal S1c, the first lower switch Q1c in the first arm 104 conducts with high - frequency switching, and under the control of the second control signal S2a, the second lower switch Q2a in the second arm 105 conducts constantly.

[0076] During the negative half - cycle of the line voltage Vmac, under the control of the first control signal S1c, the first lower switch Q1c in the first arm 104 conducts constantly, and under the control of the second control signal S2a, the second lower switch Q2a in the second arm 105 conducts with high - frequency switching.

[0077] It can be understood that during the positive half - cycle of Vmba:

[0078] When Q1a conducts and Q2b conducts, and the B - phase alternating current Ib on the B - phase line is positive - polarity, the B - phase line, the negative DC bus BUS2 -, Q2b, the energy - storage inductor L1, Q1a, the negative DC bus BUS1 -, and the A - phase line are connected, and Ib can flow through Q2b, the energy - storage inductor L1, Q1a in sequence, and then flow to the A - phase line.

[0079] When Q1a turns off and Q2b conducts, and the B - phase alternating current Ib on the B - phase line is positive - polarity, the B - phase line, the negative DC bus BUS2 -, Q2b, the energy - storage inductor L1, D1a, the positive DC bus BUS1 +, the output capacitor C1, and the A - phase line are connected, and Ib flows through Q2b, the energy - storage inductor L1, D1a in sequence, and then flows to the output capacitor C1 and the load R1 across the output capacitor C1.

[0080] When Q1a conducts and Q2b conducts, and the B - phase alternating current Ib on the B - phase line is negative - polarity, the A - phase line, the negative DC bus BUS1 -, Q1a, the energy - storage inductor L1, Q2b, the negative DC bus BUS2 -, and the B - phase line are connected, and Ib can flow through Q1a, the energy - storage inductor L1, Q2b in sequence and then flow to the B - phase line.

[0081] When Q1a turns off and Q2b conducts, and the B - phase alternating current Ib on the B - phase line is negative - polarity, the A - phase line, the negative DC bus BUS1 -, the body diode of Q1a, the energy - storage inductor L1, Q2b, the negative DC bus BUS2 -, and the B - phase line are connected, and Ib flows through the body diode of Q1a, the energy - storage inductor L1, Q2b in sequence and then flows to the B - phase line.

[0082] During the negative half-cycle of Vmba:

[0083] When Q1a is conducting and Q2b is conducting, and the B-phase alternating current Ib on the B-phase line is of negative polarity, the A-phase line, the negative DC bus BUS1-, Q1a, the energy storage inductor L1, Q2b, the negative DC bus BUS2-, and the B-phase line are connected, and Ib can flow through Q1a, the energy storage inductor L1, Q2b in sequence and then to the B-phase line.

[0084] When Q1a is conducting and Q2b is off, and the B-phase alternating current Ib on the B-phase line is of negative polarity, the A-phase line, the negative DC bus BUS1-, Q1a, the energy storage inductor L1, D2b, the positive DC bus BUS2+, the output capacitor C2, and the B-phase line are connected.

[0085] When Q1a is conducting and Q2b is conducting, and the B-phase alternating current Ib on the B-phase line is of positive polarity, the B-phase line, the negative DC bus BUS2-, Q2b, the energy storage inductor L1, Q1a, the negative DC bus BUS1-, and the A-phase line are connected, and Ib can flow through Q2b, the energy storage inductor L1, Q1a in sequence and then to the A-phase line.

[0086] When Q1a is conducting and Q2b is off, and the B-phase alternating current Ib on the B-phase line is of positive polarity, the B-phase line, the negative DC bus BUS2-, the body diode of Q2b, the energy storage inductor L1, Q1a, the negative DC bus BUS1-, and the A-phase line are connected, and Ib flows through the body diode of Q2b, the energy storage inductor L1, Q1a in sequence and then to the A-phase line.

[0087] It should be understood that during the positive or negative half-cycle of Vmba, the flow direction of the A-phase alternating current Ia on the A-phase line can be referred to the foregoing description and will not be elaborated here.

[0088] In the above process, when the current flows out through the lower switch tube Q1a of the switch tube module 101 or the body diode of the lower switch tube Q1a, the energy storage inductor L1 can store energy at this time, and the output capacitor C1 pre-stores a certain amount of electric energy and can discharge to the load R1. When the current flows to the output capacitor C2 through the lower switch tube Q2b of the switch tube module 102 or the body diode of the lower switch tube Q2b, the energy storage inductor L1 can store energy at this time, and the output capacitor C2 pre-stores a certain amount of electric energy and can discharge to the load R2.

[0089] When the current flows through the upper switch D1a of the switch tube module 101 to the output capacitor C1, the output capacitor C1 can be charged, the load R1 can be powered, and the energy storage inductor L1 can discharge, causing the output capacitor C1 to be further charged. When the current flows through the upper switch D2b of the switch tube module 102 to the output capacitor C2, the output capacitor C2 can be charged, the load R2 can be powered, and the energy storage inductor L1 can discharge, causing the output capacitor C2 to be further charged.

[0090] In the positive or negative half-cycle of Vmcb, when the first lower switch Q1b and the second lower switch Q2c are conducting simultaneously or not simultaneously, and the polarities of the currents Ic and Ib are positive or negative, the operating conditions of the circuit can be referred to the foregoing description.

[0091] In the positive or negative half-cycle of Vmac, when the first lower switch Q1c and the second lower switch Q2a are conducting simultaneously or not simultaneously, the operating conditions of the circuit can also be referred to the foregoing description. Therefore, it will not be elaborated here.

[0092] It can be understood that through the coordinated operation of the switch tube modules 101, 102, 103 and the energy storage inductors L1, L2, L3 in the power conversion circuit 100, the energy storage capacitors C1, C2, C3 can all output direct current, and the three loads R1, R2, R3 can all be powered. Moreover, the voltage polarities of the output capacitors C1, C2, C3 can remain unchanged, that is, they are always direct current voltages. Among them, when the output capacitor C1 / C2 / C3 is charged, the voltage of the output capacitor C1 / C2 / C3 can be raised due to the discharge of the energy storage inductor connected to the corresponding switch tube module.

[0093] Please refer to Figure 4 , which is the circuit diagram of the power conversion circuit 100 provided for the second embodiment. As Figure 4 shown, the power conversion circuit 100 includes three switch tube modules 101, 102, 103 and three energy storage inductors L1, L2, L3. Each switch tube module includes a first bridge arm 104, a second bridge arm 105, an output capacitor (C1 or C2 or C3), a positive DC bus (BUS1+ or BUS2+ or BUS3+), and a negative DC bus (BUS1- or BUS2- or BUS3-).

[0094] Among them, in the switch tube module 101, the first bridge arm 104 includes a first upper switch Q1a' and a first lower switch Q1a, and the second bridge arm 105 includes a second upper switch Q2a' and a second lower switch Q2a.

[0095] In the switch tube module 102, the first bridge arm 104 includes a first upper switch Q1b' and a first lower switch Q1b, and the second bridge arm 105 includes a second upper switch Q2b' and a second lower switch Q2b.

[0096] In the switching tube module 103, the first arm 104 includes a first upper switching tube Q1c' and a first lower switching tube Q1c, and the second arm 105 includes a second upper switching tube Q2c' and a second lower switching tube Q2c.

[0097] The difference between the second embodiment and the first embodiment is that the first upper switching tubes Q1a', Q1b', Q1c' and the second upper switching tubes Q2a', Q2b', Q2c' in the second embodiment are all power switching tubes.

[0098] Among them, the first connection ends of the first upper switching tube Q1a' and the second upper switching tube Q2a' are both connected to the positive DC bus BUS1+, the second connection end of the first upper switching tube Q1a' is connected to the first connection end of the first lower switching tube Q1a, the second connection end of the second upper switching tube Q2a' is connected to the first connection end of the second lower switching tube Q2a, and the second connection ends of the first lower switching tube Q1a and the second lower switching tube Q2a are both connected to the negative DC bus BUS1-. That is, the first upper switching tube Q1a' and the first lower switching tube Q1a in the same first arm 104 are connected in series, and the second upper switching tube Q2a' and the second lower switching tube Q2a in the same second arm 105 are connected in series.

[0099] Similarly, the first upper power tube Q1b' and the first lower power tube Q1b in the same first arm 104 are connected in series, the second upper power tube Q2b' and the second lower power tube Q2b in the same second arm 105 are connected in series, the first upper power tube Q1c' and the first lower power tube Q1c in the same first arm 104 are connected in series, and the second upper power tube Q2c' and the second lower power tube Q2c in the same second arm 105 are connected in series. The connection and on-off conditions of the first upper switching tube Q1b' and the second upper switching tube Q2b', the first upper switching tube Q1c' and the second upper switching tube Q2c' can refer to those of the first upper switching tube Q1a' and the second upper switching tube Q2a', and will not be elaborated here.

[0100] Correspondingly, the difference between the second embodiment and the first embodiment is also that the operating principle of the power conversion circuit provided in the second embodiment is different from that of the power conversion circuit in the first embodiment. Specifically, in the second embodiment, not only the lower switching tubes of the first arm 104 and the second arm 105 need to switch the on-off state, but also the upper switching tubes of the first arm 104 and the second arm 105 need to switch the on-off state.

[0101] For example, the controller can generate two opposite first control signals S1a, S1a' and two opposite second control signals S2b, S2b' according to the line voltage Vmba and the preset carrier signal Vcar. Among them, the first control signal S1a is used to control the on-off state of the first lower switch Q1a in the first bridge arm 104, and the first control signal S1a' is used to control the on-off state of the first upper switch Q1a' in the first bridge arm 104. The second control signal S2b is used to control the on-off state of the second lower switch Q2b in the second bridge arm 105, and the second control signal S2b' is used to control the on-off state of the second upper switch Q2b' in the second bridge arm 105.

[0102] Similarly, the controller can generate two opposite first control signals S1b, S1b' and two opposite second control signals S2c, S2c' according to the line voltage Vmcb and the preset carrier signal Vcar. Among them, the first control signal S1b is used to control the on-off state of the first lower switch Q1b in the first bridge arm 104, and the first control signal S1b' is used to control the on-off state of the first upper switch Q1b' in the first bridge arm 104. The second control signal S2c is used to control the on-off state of the second lower switch Q2c in the second bridge arm 105, and the second control signal S2c' is used to control the on-off state of the second upper switch Q2c' in the second bridge arm 105.

[0103] Similarly, the controller can generate two opposite first control signals S1c, S1c' and two opposite second control signals S2a, S2a' according to the line voltage Vmac and the preset carrier signal Vcar. Among them, the first control signal S1c is used to control the on-off state of the first lower switch Q1c in the first bridge arm 104, and the first control signal S1c' is used to control the on-off state of the first upper switch Q1c' in the first bridge arm 104. The second control signal S2a is used to control the on-off state of the second lower switch Q2a in the second bridge arm 105, and the second control signal S2a' is used to control the on-off state of the second upper switch Q2a' in the second bridge arm 105.

[0104] Specifically, the first upper switch and the first lower switch in the same first bridge arm 104 conduct complementary, and the second upper switch and the second lower switch in the same second bridge arm 105 conduct complementary.

[0105] For example, in the positive half-cycle of the line voltage Vmba, the first control signal S1a is used to control the high-frequency switching conduction of the first lower switch Q1a, the first control signal S1a' is used to control the complementary conduction of the first upper switch Q1a' and the first lower switch Q1a, the second control signal S2b is used to control the constant conduction of the second lower switch Q2b in the second bridge arm 105, and the second control signal S2b' is used to control the constant turn-off of the second upper switch Q2b' in the second bridge arm 105 (i.e., to control the complementary conduction of the second upper switch Q2b' and the second lower switch Q2b).

[0106] In the negative half-cycle of the line voltage Vmba, the second control signal S2b is used to control the high-frequency switching conduction of the second lower switch Q2b in the second bridge arm 105, the second control signal S2b' is used to control the complementary conduction of the second upper switch Q2b' and the second lower switch Q2b in the second bridge arm 105, the first control signal S1a is used to control the constant conduction of the first lower switch Q1a in the first bridge arm 104, and the first control signal S1a' is used to control the constant turn-off of the first upper switch Q1a' in the first bridge arm 104 (i.e., to control the complementary conduction of the first upper switch Q1a' and the first lower switch Q1a).

[0107] For example, in the positive half-cycle of the line voltage Vmcb, the first control signal S1b is used to control the high-frequency switching conduction of the first lower switch Q1b in the first bridge arm 104, and the first control signal S1b' is used to control the complementary conduction of the first upper switch Q1b' and the first lower switch Q1b in the first bridge arm 104. The second control signal S2c can be used to control the constant conduction of the second lower switch Q2c in the second bridge arm 105, and the second control signal S2c' can be used to control the constant turn-off of the second upper switch Q2c' in the second bridge arm 105 (i.e., to control the complementary conduction of the second upper switch Q2c' and the second lower switch Q2c).

[0108] In the negative half-cycle of the line voltage Vmcb, the first control signal S1b is used to control the constant conduction of the first lower switch Q1b in the first bridge arm 104, and the first control signal S1b' is used to control the constant turn-off of the first upper switch Q1b' in the first bridge arm 104 (i.e., to control the complementary conduction of the first upper switch Q1b' and the first lower switch Q1b). The second control signal S2c can be used to control the high-frequency switching conduction of the second lower switch Q2c in the second bridge arm 105, and the second control signal S2c' can be used to control the complementary conduction of the second upper switch Q2c' and the second lower switch Q2c in the second bridge arm 105.

[0109] For example, in the positive half-cycle of the line voltage Vmac, the first control signal S1c can be used to control the high-frequency switching conduction of the first lower switch Q1c in the first arm 104, and the first control signal S1c' can be used to control the complementary conduction of the first upper switch Q1c' and the first lower switch Q1c in the first arm 104. The second control signal S2a can be used to control the constant conduction of the second lower switch Q2a in the second arm 105, and the second control signal S2a' can be used to control the constant turn-off of the second upper switch Q2a' in the second arm 105 (i.e., control the complementary conduction of the second upper switch Q2a' and the second lower switch Q2a).

[0110] In the negative half-cycle of the line voltage Vmac, the first control signal S1c can be used to control the constant conduction of the first lower switch Q1c in the first arm 104, and the first control signal S1c' can be used to control the constant turn-off of the first upper switch Q1c' in the first arm 104 (i.e., control the complementary conduction of the first upper switch Q1c' and the first lower switch Q1c). The second control signal S2a can be used to control the high-frequency switching conduction of the second lower switch Q2a in the second arm 105, and the second control signal S2a' can be used to control the complementary conduction of the second upper switch Q2a' in the second arm 105.

[0111] It should be understood that other descriptions of the structure and working principle of the power conversion circuit 100 in the second embodiment can refer to the relevant descriptions in the first embodiment and will not be repeated here.

[0112] Generally speaking, the embodiments of the present application propose a new power conversion circuit. By designing the structure of three switch tube modules, the connection relationships between the three switch tube modules and the three energy storage inductors, and the connection relationships between the three switch tube modules and the AC power supply 200, the conversion of each-phase alternating current to direct current and power factor correction can be achieved, and multi-port output can also be realized.

[0113] Moreover, in the power conversion circuit of the embodiments of the present application, by connecting the negative DC bus of the switch tube module to the phase wire of the AC power supply, the input and output ends of the power conversion circuit are connected in a common-ground manner, thereby suppressing common-mode noise interference and reducing circulating current at the source. That is to say, in the power conversion circuit of the embodiments of the present application, by improving the connection relationship, the common-mode noise interference can be effectively improved without adding additional auxiliary circuits or filtering circuits, so that the power density reduction and cost increase of the power conversion circuit can be avoided.

[0114] During the operation of the power conversion circuit according to the embodiments of the present application, the power conversion circuit can switch the on-off states of the power tubes in the same group of bridge arms according to the positive and negative half-cycles of the line voltage formed by the same group of bridge arms, so that the inductor current of the energy storage inductor connected to the same group of bridge arms follows the change of the line voltage of the same group of bridge arms. In this way, the line voltage of the same group of bridge arms and the inductor current of the energy storage inductor always present a sinusoidal waveform, without distortion, and the phases are close (see Figure 3 ). In addition, the circuit can also achieve step-up. Therefore, the power conversion circuit 100 according to the embodiments of the present application is essentially a step-up PFC circuit.

[0115] In addition, the power conversion circuit of the present application can design the first bridge arm and the second bridge arm according to the actual situation. For example, it can be designed that both the first bridge arm and the second bridge arm are composed of a diode and a power switch tube, or it can be designed that both the first bridge arm and the second bridge arm are composed of two power switch tubes. Therefore, the design flexibility is high.

[0116] It should be understood that in the power conversion circuit of Embodiment 1, each switch tube module and the energy storage inductor connected thereto constitute a standard bridgeless PFC circuit. Currently, the standard bridgeless PFC is basically only applied to the single-phase field. However, through the improvement of the standard bridgeless PFC circuit in Embodiment 1, the standard bridgeless PFC circuit can be applied to the three-phase field, thus broadening the application field of the standard bridgeless PFC. Moreover, the current single-phase standard bridgeless PFC has a serious problem of common-mode noise interference. However, based on its own circuit connection design, the power conversion circuit of Embodiment 1 can effectively reduce the common-mode noise interference without adding an auxiliary circuit or a filtering circuit. Therefore, the power conversion circuit of Embodiment 1 has the advantages of low common-mode noise, simple structure, low cost, small volume, and high power density.

[0117] Similarly, based on its own circuit connection design, the power conversion circuit of Embodiment 2 can effectively reduce the common-mode noise interference without adding an auxiliary circuit or a filtering circuit. Therefore, the power conversion circuit of Embodiment 2 also has the advantages of low common-mode noise, simple structure, low cost, small volume, and high power density.

[0118] In addition, in the switch tube module of Embodiment 1, both the first bridge arm and the second bridge arm are composed of a diode and a power switch tube. Compared with the series-connected upper and lower power switch tubes that need to consider the dead time and prevent the bridge arm from being directly connected, the power conversion circuit of the present application does not need to involve the dead time, and there is no problem of the bridge arm being directly connected and short-circuited. Therefore, the working complexity is lower, the use reliability is higher, and the circuit cost is also lower.

[0119] In the switch tube module of Embodiment 2, both the first bridge arm and the second bridge arm are composed of two power switch tubes. Therefore, the power conversion circuit of Embodiment 2 can change the voltage conversion by controlling the on-off state switching of the two switch tubes of each bridge arm, and the control flexibility of the circuit is high.

[0120] It can be understood that an embodiment of the present application further provides a power conversion device 1000. The power conversion device 1000 can be applied to fields such as energy storage power supplies, data centers, charging stations, automobiles, and base stations.

[0121] Please refer to Figure 4 , the power conversion device 1000 may include a power conversion circuit 100 and a controller 400. The power conversion circuit 100 is connected to the controller 400. The power conversion circuit 100 can also be used to connect to an AC power supply 200 and a load 300.

[0122] Among them, the power conversion circuit 100 can be the power conversion circuit 100 of Embodiment 1 or 2. The controller 400 can be used to control the power conversion circuit 100 to convert the three-phase alternating current provided by the AC power supply 200 into direct current and then supply it to the load 300. The power conversion circuit 100 and the controller 400 can be at least partially integrated together or can be separately and independently arranged. The power conversion circuit 100 and the controller 400 can both refer to the relevant descriptions in the foregoing embodiments and will not be elaborated here.

[0123] In some embodiments, the power conversion device 1000 may further include a DC conversion circuit. The DC conversion circuit can be any circuit that can implement the DC conversion function. The power conversion circuit 100 is connected to the load 300 through the DC conversion circuit. Therefore, the direct current output by the power conversion circuit 100 can be converted into another direct current that meets the load specifications through the DC conversion circuit and then transmitted to the load 300.

[0124] It can be understood that an embodiment of the present application further provides an energy storage device 2000. The energy storage device 2000 can be applied to fields such as photovoltaic energy storage, data centers, automobiles, and base stations.

[0125] Please refer to Figure 5 , the energy storage device 2000 may include the above-mentioned power conversion circuit 100, DC conversion circuit 500, and battery pack 600. The power conversion circuit 100 is connected to the battery pack 600 through the DC conversion circuit 500. The energy storage device 2000 may further include a controller 400. The controller 400 is connected to the power conversion circuit 100. The controller 400 can be used to control the operation of the power conversion circuit 100 so that the power conversion circuit 100 converts the electrical energy of the AC power supply 200 and supplies it to the battery pack 600 through the DC conversion circuit 500, enabling the battery pack 600 to be charged. Therefore, the battery pack 600 is equivalent to a load.

[0126] Among them, the power conversion circuit 100, the DC conversion circuit 500, the battery pack 600, and the controller 400 can be at least partially integrated into one body, or can be separately and independently arranged. The power conversion circuit 100, the DC conversion circuit 500, the controller 400, and the battery pack 600 can all refer to the relevant descriptions in the foregoing embodiments, and will not be repeated here.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A power conversion circuit, characterized in that: The power conversion circuit includes: three switch tube modules and three energy storage inductors; Each of the switch tube modules comprises a first bridge arm, a second bridge arm, an output capacitor, a positive DC bus and a negative DC bus, wherein the first bridge arm, the second bridge arm and both ends of the output capacitor are connected in parallel between the positive DC bus and the negative DC bus; wherein the first bridge arm comprises a first upper switch tube and a first lower switch tube connected to each other, and the second bridge arm comprises a second upper switch tube and a second lower switch tube connected to each other; The midpoint of the first bridge arm in each of the switch tube modules is connected to the midpoint of the second bridge arm in another of the switch tube modules through one of the energy storage inductors, and the midpoint of the second bridge arm in each of the switch tube modules is connected to the midpoint of the first bridge arm in the remaining switch tube module through another of the energy storage inductors; The negative DC busbars in the three switch tube modules are connected one-to-one with the three-phase lines of the AC power supply. The three switch tube modules are respectively used to access the corresponding one-phase AC power of the AC power supply and output DC power through the output capacitor.

2. The power conversion circuit according to claim 1, characterized in that: The first upper switch tube and the second upper switch tube are both diodes, and the first lower switch tube and the second lower switch tube are both power switch tubes, wherein the first upper switch tube and the first lower switch tube in the same first bridge arm are connected in reverse series, and the second upper switch tube and the second lower switch tube in the same second bridge arm are connected in reverse series.

3. The power conversion circuit according to claim 2, characterized in that: The first bridge arm and the second bridge arm connected to the same energy storage inductor form a group of bridge arms, and a corresponding one-phase line voltage is formed between the first bridge arm and the second bridge arm in the same group; In the positive half cycle of the line voltage corresponding to the bridge arms of the same group, the first lower switch tube in the first bridge arm of the same group is constantly turned on, and the second lower switch tube in the second bridge arm of the same group is switched on at a high frequency; In the negative half cycle of the line voltage corresponding to the bridge arms of the same group, the first lower switch tube in the first bridge arm of the same group is switched on at high frequency, and the second lower switch tube in the second bridge arm of the same group is constantly turned on.

4. The power conversion circuit according to claim 1, characterized in that: The first upper switch tube, the second upper switch tube, the first lower switch tube and the second lower switch tube are all power switch tubes, wherein the first upper switch tube in the same first bridge arm is connected in series with the first lower switch tube, and the second upper switch tube in the same second bridge arm is connected in series with the second lower switch tube.

5. The power conversion circuit according to claim 4, characterized in that: The first bridge arm and the second bridge arm connected to the same energy storage inductor form a group of bridge arms, and a corresponding one-phase line voltage is formed between the first bridge arm and the second bridge arm in the same group; In the positive half cycle of the line voltage corresponding to the bridge arm of the same group, the first lower switch tube in the first bridge arm of the same group is controlled to be constantly turned on and the first upper switch tube is constantly turned off, the second lower switch tube in the second bridge arm of the same group is switched on at high frequency, and the second upper switch tube and the second lower switch tube are complementary turned on; Furthermore, in the negative half cycle of the line voltage corresponding to the bridge arm of the same group, the first lower switch tube in the first bridge arm of the same group is controlled to switch on at high frequency, and the first upper switch tube and the first lower switch tube are complementarily turned on, and the second lower switch tube in the second bridge arm of the same group is constantly turned on and the second upper switch tube is constantly turned off.

6. The power conversion circuit according to claim 2, characterized in that: The power switch tube includes at least one of a metal oxide semiconductor field effect transistor, an insulated gate bipolar transistor and a gallium nitride high electron mobility transistor; the diode includes at least one of an ultrafast recovery diode and a silicon carbide Schottky diode.

7. The power conversion circuit according to claim 4, characterized in that: The power switch tube includes at least one of a metal oxide semiconductor field effect transistor, an insulated gate bipolar transistor and a gallium nitride high electron mobility transistor.

8. A power conversion device, characterized in that: The power conversion device includes a power conversion circuit and a controller. The power conversion circuit includes three switch tube modules and three energy storage inductors, wherein: Each of the switch tube modules comprises a first bridge arm, a second bridge arm, an output capacitor, a positive DC bus and a negative DC bus, wherein the first bridge arm, the second bridge arm and both ends of the output capacitor are connected in parallel between the positive DC bus and the negative DC bus; wherein the first bridge arm comprises a first upper switch tube and a first lower switch tube connected to each other, and the second bridge arm comprises a second upper switch tube and a second lower switch tube connected to each other; The midpoint of the first bridge arm in each of the switch tube modules is connected to the midpoint of the second bridge arm in another of the switch tube modules through one of the energy storage inductors, and the midpoint of the second bridge arm in each of the switch tube modules is connected to the midpoint of the first bridge arm in the remaining switch tube module through another of the energy storage inductors; The negative DC busbars in the three switch tube modules are connected to the three-phase lines of the AC power supply in a one-to-one correspondence; The three switch tube modules are also connected to the controller, and the controller outputs a control signal to the three switch tube modules. The control signal is used to control the three switch tube modules to jointly convert the three-phase AC power connected to the AC power supply into DC power.

9. The power conversion device according to claim 8, characterized in that: The controller outputs a first control signal to the first bridge arm among the three switch tube modules, and outputs a second control signal to the second bridge arm among the three switch tube modules, wherein the first control signal is used to control the on-off state of the switch tube of the first bridge arm, and the second control signal is used to control the on-off state of the switch tube of the second bridge arm.

10. An energy storage device, characterized in that: The energy storage device includes a power conversion circuit, a DC conversion circuit and a battery pack, wherein the power conversion circuit is connected to the battery pack via the DC conversion circuit, wherein the power conversion circuit is the power conversion circuit as described in any one of claims 1 to 7.

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