Ac-dc conversion circuit and method of operation thereof

Abstract

An AC-DC conversion circuit and a method of operating the same. The AC-DC conversion circuit includes a power measurement circuit, a control circuit, and three bridge arm circuits. Each of the bridge arm circuits includes a plurality of switches. The power measurement circuit is configured to measure at least one of an input power and an output power to generate a power measurement value. When the power measurement value is less than a power threshold, the control circuit controls the switches of the three bridge arm circuits to set the three bridge arm circuits to operate in a light load mode. When the power measurement value is greater than the power threshold, the control circuit controls the switches of the three bridge arm circuits to set the three bridge arm circuits to operate in a heavy load mode.

Description

Technical Field

[0001] This disclosure relates to a conversion circuit and its operation method, particularly an AC-DC conversion circuit and its operation method. Background Technology

[0002] Currently, various pulse width modulation (PWM) modes are available for controlling power conversion devices of related technologies (e.g., active neutral point clamped (ANPC) power conversion devices). The power loss of these PWM modes varies at different power levels; some PWM modes have lower power loss at power levels below a certain threshold but higher power loss at power levels greater than or equal to that threshold, while others exhibit the opposite behavior.

[0003] In summary, current pulse width modulation (PWM) modes are not ideal, resulting in an unsatisfactory overall power loss control of power conversion devices using a single PWM mode across all power levels. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this disclosure is to provide an AC-DC conversion circuit.

[0005] To address the aforementioned problems, another objective of this disclosure is to provide a method for operating an AC-DC conversion circuit.

[0006] To achieve the aforementioned objectives of this disclosure, the disclosed AC-DC conversion circuit generates a DC output voltage based on a three-phase AC input power supply, comprising: a power measurement circuit for measuring at least one of an input power and an output power to generate a power measurement value; a control circuit coupled to the power measurement circuit; and three bridge arm circuits, each of the bridge arm circuits comprising: a first switch comprising a control terminal coupled to the control circuit, a first terminal coupled to a first output terminal via a first capacitor, and a second terminal; a second switch comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch, and a second terminal coupled to a first input power supply. A third switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the second switch and the first input inductor, and a second terminal; a fourth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch, and a second terminal coupled to the first output terminal via a second capacitor; a fifth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch, and a second terminal coupled to the first output terminal; and a sixth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a first input inductor; a third switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a fourth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch and the first output terminal, and a fifth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch and the first output terminal, and a fifth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch and the first output terminal, and a sixth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a fifth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch and the first input inductor, and a sixth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal ... third switch and the first input inductor, and a sixth switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch and the first output terminal, and a sixth switch, comprising a control terminal coupled The two terminals are coupled to the second terminal of the third switch and the first terminal of the fourth switch. When the power measurement value is less than a power threshold, the control circuit sets the three bridge arm circuits to operate in a light load mode: In the first positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch coupled to the first bridge arm circuit of the first single-phase AC power supply to be turned on, and sets the third and fourth switches to be turned off; In a charging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned off, and sets the fifth switch to be turned on; In a discharging mode of the first positive half-cycle signal, the... The control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fifth switch to be turned off; in a first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch and the second switch of the first bridge arm circuit to be turned off, and sets the third switch to be turned on; in a charging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be turned off, and sets the sixth switch to be turned on; in a discharging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be turned on, and sets the sixth switch to be turned off.When the measured power value exceeds the power threshold, the control circuit sets the three bridge arm circuits to operate in a heavy-load mode: during a second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second and sixth switches of the first bridge arm circuit to be turned on, and sets the fourth switch to be turned off; during a charging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned off, and sets the third and fifth switches to be turned on; during a discharging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned on. Furthermore, the third and fifth switches are set to be off; during a second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch of the first bridge arm circuit to be off, and sets the third and fifth switches to be on; during a charging mode of the second negative half-cycle signal, the control circuit sets the second and sixth switches of the first bridge arm circuit to be on, and sets the fourth switch to be off; during a discharging mode of the second negative half-cycle signal, the control circuit sets the second and sixth switches of the first bridge arm circuit to be off, and sets the fourth switch to be on.

[0007] To achieve another objective disclosed herein, the AC-DC conversion circuit operation method disclosed herein uses an AC-DC conversion circuit to generate a DC output voltage based on a three-phase AC input power supply. The AC-DC conversion circuit includes a power measurement circuit, a control circuit, and three bridge arm circuits. The control circuit is coupled to the power measurement circuit. Each bridge arm circuit includes: a first switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to a first output terminal via a first capacitor, and a second terminal; a second switch, comprising a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch, and a second terminal coupled to a first input inductor; and a third switch, comprising a control terminal coupled to a... The control circuit includes a first terminal coupled to the second terminal of the second switch and the first input inductor, and a second terminal; a fourth switch including a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch, and a second terminal coupled to the first output terminal via a second capacitor; a fifth switch including a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch, and a second terminal coupled to the first output terminal; and a sixth switch including a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a second terminal coupled to the second terminal of the third switch and the first terminal of the fourth switch. An AC-DC converter circuit operation method includes: the power measurement circuit measuring at least one of an input power and an output power to generate a power measurement value; when the power measurement value is less than a power threshold, the control circuit sets the three bridge arm circuits to operate in a light load mode: during a first positive half-cycle signal of a first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch coupled to the first bridge arm circuit of the first single-phase AC power supply to be turned on, and sets the third and fourth switches to be turned off; during a charging mode of the first positive half-cycle signal, the control circuit sets the first and sixth switches of the first bridge arm circuit to be turned off, and sets the fifth switch to be turned on; during the first positive half-cycle... In a discharge mode of the signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fifth switch to be turned off; in a first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch and the second switch of the first bridge arm circuit to be turned off, and sets the third switch to be turned on; in a charging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be turned off, and sets the sixth switch to be turned on; in a discharge mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be turned on, and sets the sixth switch to be turned off.When the measured power value exceeds the power threshold, the control circuit sets the three bridge arm circuits to operate in a heavy-load mode: during a second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second and sixth switches of the first bridge arm circuit to be turned on, and sets the fourth switch to be turned off; during a charging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned off, and sets the third and fifth switches to be turned on; during a discharging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned on. Furthermore, the third and fifth switches are set to be non-conductive; during a second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch of the first bridge arm circuit to be non-conductive, and sets the third and fifth switches to be conductive; during a charging mode of the second negative half-cycle signal, the control circuit sets the second and sixth switches of the first bridge arm circuit to be conductive, and sets the fourth switch to be non-conductive; during a discharging mode of the second negative half-cycle signal, the control circuit sets the second and sixth switches of the first bridge arm circuit to be non-conductive, and sets the fourth switch to be conductive.

[0008] The benefit of this disclosure is to reduce the overall power loss of AC-DC conversion circuits.

[0009] To further understand the techniques, methods, and effects of this disclosure and to achieve the intended purpose of this disclosure, please refer to the following detailed description and accompanying drawings; furthermore, the purpose, characteristics, and features of this disclosure can be understood more deeply and specifically; however, the accompanying drawings are provided for reference and description only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0010] Figure 1 This is a circuit block diagram of a first embodiment of the AC-DC conversion circuit disclosed herein;

[0011] Figure 2 A power-power loss comparison diagram of an embodiment of the first pulse width modulation mode and the second pulse width modulation mode disclosed herein;

[0012] Figure 3 This is a waveform comparison diagram of the light load mode disclosed herein;

[0013] Figure 4 This is a waveform comparison diagram of the overload mode disclosed herein;

[0014] Figure 5 This is a circuit block diagram of a second embodiment of the AC-DC conversion circuit disclosed herein;

[0015] Figure 6This is a circuit block diagram of a third embodiment of the AC-DC conversion circuit disclosed herein;

[0016] Figure 7 A block diagram of one embodiment of the logic circuit disclosed herein;

[0017] Figure 8 This is a flowchart illustrating the operation of the AC-DC conversion circuit disclosed herein.

[0018] [Symbol Explanation]

[0019] 1N: First negative half-cycle signal

[0020] 1P: First positive half-cycle signal

[0021] 2N: Second negative half-cycle signal

[0022] 2P: Second positive half-cycle signal

[0023] 10: AC-DC conversion circuit

[0024] 20: Three-phase AC input power supply

[0025] 22: DC output voltage

[0026] 102: Power Measurement Circuit

[0027] 104: Control Circuit

[0028] 108: First output terminal

[0029] 110: Logic Circuits

[0030] 1022: Power Calculation Circuit

[0031] 1023: Power Threshold Judgment Circuit

[0032] 1024: Control signal generation circuit

[0033] 1026: Current Sensor

[0034] 1028: Voltage Sensor

[0035] 1062: First bridge arm circuit

[0036] 1064: Second Bridge Arm Circuit

[0037] 1066: Third bridge arm circuit

[0038] 1101: AND Gate

[0039] 1102: OR gate

[0040] AC1: First single-phase AC power supply

[0041] AC2: Second single-phase AC power supply

[0042] AC3: Third single-phase AC power supply

[0043] C: Charging pulse width modulation signal

[0044] C1: First capacitor

[0045] C2: Second capacitor

[0046] D: Discharge pulse width modulation signal

[0047] HL: Overload mode

[0048] IL1: First inductor current

[0049] L1: First input inductor

[0050] L2: Second input inductor

[0051] L3: Third Input Inductor

[0052] LL: Light load mode

[0053] N: Negative half-cycle pulse width modulation signal

[0054] P: Positive half-cycle pulse width modulation signal

[0055] PWM1: First pulse width modulation mode

[0056] PWM2: Second Pulse Width Modulation Mode

[0057] Q0: Control signal

[0058] Q1: First control signal

[0059] Q2: Second control signal

[0060] Q3: Third control signal

[0061] Q4: Fourth control signal

[0062] Q5: Fifth control signal

[0063] Q6: Sixth control signal

[0064] S02: Steps

[0065] S04: Steps

[0066] S06: Steps

[0067] S08: Steps

[0068] S1: First switch

[0069] S2: Second switch

[0070] S3: Third switch

[0071] S4: Fourth Switch

[0072] S5: Fifth Switch

[0073] S6: Sixth Switch Detailed Implementation

[0074] Numerous specific details are provided in this disclosure to provide a comprehensive understanding of the embodiments thereof; however, those skilled in the art will understand that this disclosure may be practiced without one or more of these specific details; in other instances, well-known details have not been shown or described to avoid obscuring the features of this disclosure. The technical content and detailed description of this disclosure are as follows, and are illustrated with accompanying drawings.

[0075] Please refer to Figure 1 This is a circuit block diagram of a first embodiment of the AC-DC conversion circuit 10 disclosed herein. The AC-DC conversion circuit 10 disclosed herein is used to generate a DC output voltage 22 based on a three-phase AC input power supply 20. The AC-DC conversion circuit 10 includes a power measurement circuit 102, a control circuit 104, and three bridge arm circuits (i.e., a first bridge arm circuit 1062, a second bridge arm circuit 1064, and a third bridge arm circuit 1066). The power measurement circuit 102 includes multiple current sensors 1026 and multiple voltage sensors 1028. The control circuit 104 includes a power calculation circuit 1022, a power threshold determination circuit 1023, and a control signal generation circuit 1024.

[0076] The power calculation circuit 1022 of the control circuit 104 is coupled to the current sensors 1026 and voltage sensors 1028 of the power measurement circuit 102; for simplification Figure 1 , Figure 1 The wiring connecting the power calculation circuit 1022 of the control circuit 104 to the current sensors 1026 and the voltage sensors 1028 is omitted. In each bridge arm circuit, the current sensor 1026 and the voltage sensor 1028 measure the current and voltage respectively so that the power calculation circuit 1022 of the control circuit 104 calculates the input power (e.g., using the formula: power equals current multiplied by voltage). The power calculation circuit 1022 can calculate one or more of the input power of the three bridge arm circuits (e.g., calculate the sum of the input power of the three bridge arm circuits).

[0077] Each of the bridge arm circuits includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, and a sixth switch S6; these switches can be transistor switches (for example, all of these switches are N-channel metal-oxide-semiconductor field-effect transistors, NPN bipolar transistors, silicon carbide transistors, gallium nitride transistors, and insulated-gate bipolar transistors).

[0078] Figure 1 The wiring from the control signal generation circuit 1024 of the control circuit 104 to the control terminals of all these switches is omitted. Taking the first bridge arm circuit 1062 as an example: the first switch S1 includes a control terminal coupled to the control signal generation circuit 1024 of the control circuit 104, a first terminal coupled to a first output terminal 108 via a first capacitor C1, and a second terminal. The second switch S2 includes a control terminal coupled to the control signal generation circuit 1024 of the control circuit 104, a first terminal coupled to the second terminal of the first switch S1, and a second terminal coupled to a first input inductor L1 (for the second bridge arm circuit 1064, the second terminal 2E is coupled to a second input inductor L2; for the third bridge arm circuit 1066, the second terminal 2E is coupled to a third input inductor L3). The third switch S3 includes a control signal generating circuit 1024 with a control terminal coupled to the control circuit 104, a first terminal coupled to the second terminal of the second switch S2 and the first input inductor L1 (for the second bridge arm circuit 1064, the first terminal is coupled to the second terminal of the second switch S2 and the second input inductor L2; for the third bridge arm circuit 1066, the first terminal is coupled to the second terminal of the second switch S2 and the third input inductor L3), and a second terminal. The fourth switch S4 includes a control signal generating circuit 1024 with a control terminal coupled to the control circuit 104, a first terminal coupled to the second terminal of the third switch S3, and a second terminal coupled to the first output terminal 108 via a second capacitor C2. The fifth switch S5 includes a control signal generating circuit 1024 with a control terminal coupled to the control circuit 104, a first terminal coupled to the second terminal of the first switch S1 and the first terminal of the second switch S2, and a second terminal coupled to the first output terminal 108. The sixth switch S6 includes a control signal generating circuit 1024 with a control terminal coupled to the control circuit 104, a first terminal coupled to the second terminal of the fifth switch S5 and the first output terminal 108, and a second terminal coupled to the second terminal of the third switch S3 and the first terminal of the fourth switch S4. The AC-DC conversion circuit 10 disclosed herein may also be referred to as an active neutral point clamped (ANPC) power conversion device.

[0079] Please refer to Figure 2 This is a power-power loss comparison diagram of an embodiment of the first pulse width modulation mode PWM1 and the second pulse width modulation mode PWM2 disclosed herein; please also refer to... Figure 1 This disclosure provides a first pulse width modulation mode (PWM1) and a second pulse width modulation mode (PWM2) to control these switches to generate the DC output voltage 22 according to the three-phase AC input power supply 20, while Figure 2 This illustrates an embodiment of the AC-DC conversion circuit 10, showing the power loss in the first pulse width modulation mode (PWM1) and the power loss in the second pulse width modulation mode (PWM2).

[0080] For example, when the power is 400 watts, the AC-DC converter 10 has a power loss of 1.5 watts in the first pulse width modulation mode (PWM1) and a power loss of 4 watts in the second pulse width modulation mode (PWM2); when the power is 3200 watts, the AC-DC converter 10 has a power loss of 9.5 watts in the first pulse width modulation mode (PWM1) and a power loss of 9.5 watts in the second pulse width modulation mode (PWM2); when the power is 4000 watts, the AC-DC converter 10 has a power loss of 14.5 watts in the first pulse width modulation mode (PWM1) and a power loss of 11.5 watts in the second pulse width modulation mode (PWM2).

[0081] Depend on Figure 2 As can be seen from the power-power loss comparison diagram, when the power is less than 3200 watts, the power loss of the AC-DC converter 10 in the first pulse width modulation mode (PWM1) can be lower than the power loss of the AC-DC converter 10 in the second pulse width modulation mode (PWM2); however, when the power is greater than or equal to 3200 watts, the power loss of the AC-DC converter 10 in the second pulse width modulation mode (PWM2) can be lower than the power loss of the AC-DC converter 10 in the first pulse width modulation mode (PWM1).

[0082] Therefore, in Figure 2 In this embodiment, the present disclosure uses 3200 watts as a power threshold. When the power is less than 3200 watts, the AC-DC converter circuit 10 is operated using the first pulse width modulation mode (PWM1), and when the power is greater than or equal to 3200 watts, the AC-DC converter circuit 10 is operated using the second pulse width modulation mode (PWM2), thereby minimizing the overall power loss. Therefore, the effect of this disclosure is to reduce the overall power loss of the AC-DC converter circuit. In the following text, the first pulse width modulation mode (PWM1) is referred to as the light load mode (LL), and the second pulse width modulation mode (PWM2) is referred to as the heavy load mode (HL).

[0083] Please refer to Figure 3 This is a waveform comparison diagram of the light-load mode LL disclosed herein; please also refer to... Figure 1 The power threshold determination circuit 1023 of the control circuit 104 is coupled to the power calculation circuit 1022, and compares the input power calculated by the power calculation circuit 1022 with a preset power threshold. When the power threshold determination circuit 1023 determines that the measured power value is less than the power threshold (e.g., ...), ... Figure 2 The control signal generation circuit 1024 of the control circuit 104 (shown as 3200 watts) correspondingly generates a control signal to set the three bridge arm circuits to operate in a light load mode LL (i.e., Figure 2 The first pulse width modulation mode (PWM1) shown is described in detail below, taking the first bridge arm circuit 1062 as an example. The control signal generation circuit 1024 of the control circuit 104 generates a first control signal Q1, a second control signal Q2, a third control signal Q3, a fourth control signal Q4, a fifth control signal Q5, and a sixth control signal Q6 to control the conduction states of the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, and the sixth switch S6 of the first bridge arm circuit 1062, respectively. Figure 3 It also displays the first inductor current IL1 of the first input inductor L1.

[0084] In the first positive half-cycle signal 1P of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20, regardless of whether it is in charging mode CM (charging the inductor) or discharging mode DM (discharging the inductor), the control signal generation circuit 1024 of the control circuit 104 sets the second switch S2 coupled to the first bridge arm circuit 1062 of the first single-phase AC power supply AC1 to be turned on, and sets the third switch S3 and the fourth switch S4 to be turned off; wherein in the charging mode CM of the first positive half-cycle signal 1P, the control signal generation circuit 1024 of the control circuit 104 sets the first bridge arm circuit S2 to be turned on. In circuit 1062, the first switch S1 and the sixth switch S6 are not turned on, and the fifth switch S5 is turned on (where the conduction frequency of the fifth switch S5 is different from the conduction frequency of the second switch S2); while in a discharge mode DM of the first positive half-cycle signal 1P, the control signal generation circuit 1024 of the control circuit 104 turns on the first switch S1 and the sixth switch S6 of the first bridge arm circuit 1062 (where the conduction frequency of the first switch S1 is the same as the conduction frequency of the sixth switch S6, but different from the conduction frequency of the second switch S2), and turns off the fifth switch S5.

[0085] In a first negative half-cycle signal 1N of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20, regardless of whether it is in charging mode CM or discharging mode DM, the control signal generation circuit 1024 of the control circuit 104 sets the first switch S1 and the second switch S2 of the first bridge arm circuit 1062 to be de-conducted, and sets the third switch S3 to be on; wherein in a charging mode CM of the first negative half-cycle signal 1N, the control signal generation circuit 1024 of the control circuit 104 sets the fourth switch S4 of the first bridge arm circuit 1062 to be... The fifth switch S5 is not turned on, and the sixth switch S6 is turned on (where the conduction frequency of the sixth switch S6 is different from the conduction frequency of the third switch S3); while in a discharge mode DM of the first negative half-cycle signal 1N, the control signal generation circuit 1024 of the control circuit 104 sets the fourth switch S4 and the fifth switch S5 of the first bridge arm circuit 1062 to be turned on (where the conduction frequency of the fourth switch S4 is the same as the conduction frequency of the fifth switch S5, but different from the conduction frequency of the third switch S3), and sets the sixth switch S6 to be turned off.

[0086] Please refer to Figure 4 This is a waveform comparison diagram in overload mode HL as disclosed herein; please also refer to... Figure 1 When the measured power value exceeds the power threshold, the control signal generation circuit 1024 of the control circuit 104 sets the three bridge arm circuits to operate in a heavy load mode HL (i.e., Figure 2 The second pulse width modulation mode (PWM2) shown is described in detail below, taking the first bridge arm circuit 1062 as an example:

[0087] In the second positive half-cycle signal 2P of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20, regardless of whether it is in charging mode CM or discharging mode DM, the control signal generation circuit 1024 of the control circuit 104 sets the second switch S2 and the sixth switch S6 of the first bridge arm circuit 1062 to be turned on, and sets the fourth switch S4 to be turned off; wherein, in the charging mode CM of the second positive half-cycle signal 2P, the control signal generation circuit 1024 of the control circuit 104 sets the first switch S1 of the first bridge arm circuit 1062 to be turned off, and sets the third switch S... 3. The fifth switch S5 is turned on (where the second switch S2, the third switch S3, the fifth switch S5 and the sixth switch S6 have the same conduction frequency; turning on the four switches can share the charging current and reduce conduction loss); while in the discharge mode DM of the second positive half-cycle signal 2P, the control signal generation circuit 1024 of the control circuit 104 sets the first switch S1 of the first bridge arm circuit 1062 to be turned on (where the first switch S1, the second switch S2 and the sixth switch S6 have the same conduction frequency), and sets the third switch S3 and the fifth switch S5 to be turned off.

[0088] In the second negative half-cycle signal 2N of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20, regardless of whether it is in charging mode CM or discharging mode DM, the control signal generation circuit 1024 of the control circuit 104 sets the first switch S1 of the first bridge arm circuit 1062 to be off, and sets the third switch S3 and the fifth switch S5 to be on; wherein in the charging mode CM of the second negative half-cycle signal 2N, the control signal generation circuit 1024 of the control circuit 104 sets the second switch S2 and the sixth switch S6 of the first bridge arm circuit 1062 to be on (its The second switch S2, the third switch S3, the fifth switch S5, and the sixth switch S6 all have the same conduction frequency; turning on the four switches can share the charging current and reduce conduction losses), and the fourth switch S4 is set to be off; while in the discharge mode DM of the second negative half-cycle signal 2N, the control signal generation circuit 1024 of the control circuit 104 sets the second switch S2 and the sixth switch S6 of the first bridge arm circuit 1062 to be off, and sets the fourth switch S4 to be on (wherein the third switch S3, the fourth switch S4, and the fifth switch S5 all have the same conduction frequency).

[0089] The operation of each phase's bridge arm circuit is similar or the same (therefore, it will not be described in detail here), but the phase difference is 120 degrees; that is, the phase difference of the first single-phase AC power supply AC1, the second single-phase AC power supply AC2, and the third single-phase AC power supply AC3 of the three-phase AC input power supply 20 is 120 degrees, and the control signal generation circuit 1024 of the control circuit 104 sets the phase difference of the control signals Q0 of the three bridge arm circuits (that is, the phase difference of the first control signal Q1, the second control signal Q2, the third control signal Q3, the fourth control signal Q4, the fifth control signal Q5, and the sixth control signal Q6) to be 120 degrees.

[0090] For example, in the charging mode CM, when the first bridge arm circuit 1062 is in the first positive half-cycle signal 1P of the first single-phase AC power supply AC1, the second bridge arm circuit 1064 may also be in the first positive half-cycle signal 1P of the second single-phase AC power supply AC2, and the third bridge arm circuit 1066 may be in the first negative half-cycle signal 1N of the third single-phase AC power supply AC3. Therefore, as described above, the second switch S2 and the fifth switch S5 of the first bridge arm circuit 1062 will be turned on, the second switch S2 and the fifth switch S5 of the second bridge arm circuit 1064 will also be turned on, and the third switch S3 and the sixth switch S6 of the third bridge arm circuit 1066 will be turned on.

[0091] When the input power is less than the power threshold, the power measurement circuit 102 and the control signal generation circuit 1024 of the control circuit 104 set the measured power value to a low potential, causing the control signal generation circuit 1024 of the control circuit 104 to operate the three bridge arm circuits in the light load mode LL. When the input power is greater than or equal to the power threshold, the power measurement circuit 102 and the control signal generation circuit 1024 of the control circuit 104 set the measured power value to a high potential, causing the control signal generation circuit 1024 of the control circuit 104 to operate the three bridge arm circuits in the heavy load mode HL.

[0092] Please refer to Figure 5 This is a circuit block diagram of a second embodiment of the AC-DC conversion circuit 10 disclosed herein; Figure 5 The components shown are Figure 1 For the sake of simplicity, components that are identical will not be described again here. Figure 1 The difference is, Figure 5 The current sensor 1026 and the voltage sensor 1028 of the power measurement circuit 102 are used to measure an output power to generate the power measurement value; that is, the power measurement circuit 102 disclosed herein is used to measure, for example, Figure 1 The input power shown and as Figure 5At least one of the output powers shown is used to generate the power measurement value.

[0093] When the output power is less than the power threshold, the power measurement circuit 102 and the control signal generation circuit 1024 of the control circuit 104 set the measured power value to a low potential, causing the control signal generation circuit 1024 of the control circuit 104 to operate the three bridge arm circuits in the light load mode LL. When the output power is greater than or equal to the power threshold, the power measurement circuit 102 and the control signal generation circuit 1024 of the control circuit 104 set the measured power value to a high potential, causing the control signal generation circuit 1024 of the control circuit 104 to operate the three bridge arm circuits in the heavy load mode HL.

[0094] Please refer to Figure 6 This is a circuit block diagram of the third embodiment of the AC-DC conversion circuit 10 disclosed herein; Figure 6 The components shown are Figure 1 For the sake of simplicity, the same components shown will not be described again here; please refer to [reference needed]. Figure 7 This is a block diagram of one embodiment of the logic circuit 110 disclosed herein; please also refer to... Figure 6 as well as Figure 7 .and Figure 1 The difference is, Figure 6 The AC-DC converter circuit 10 further includes a logic circuit 110, which includes multiple AND gates 1101 and multiple OR gates 1102. For simplicity... Figure 6 , Figure 6 The wiring from the logic circuit 110 to the control terminals of all these switches is omitted.

[0095] exist Figure 7 In the embodiment, the logic circuit 110 generates a first control signal Q1, a second control signal Q2, a third control signal Q3, a fourth control signal Q4, a fifth control signal Q5, and a sixth control signal Q6 based on a discharge pulse width modulation signal D, a charging pulse width modulation signal C, a positive half-cycle pulse width modulation signal P, and a negative half-cycle pulse width modulation signal N generated by the control signal generation circuit 1024 of the control circuit 104, and based on the power measurement value (referred to as L in the following logical relationship). These signals control the conduction states of the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, and the sixth switch S6 of the first bridge arm circuit 1062, respectively. The logical relationship between the signals, values, and conduction states is as follows:

[0096] Q1 = P and D

[0097] Q2 = (L and C)orP

[0098] Q3 = (L and C)orN

[0099] Q4 = N and D

[0100] Q5=Q4 or(L and Q3)or(P and C)or(L and C)

[0101] Q6=Q1 or(L and Q2)or(N and C)or(L and C)

[0102] In the charging mode CM of the first positive half-cycle signal 1P, the charging mode CM of the first negative half-cycle signal 1N, the charging mode CM of the second positive half-cycle signal 2P, and the charging mode CM of the second negative half-cycle signal 2N, the control signal generation circuit 1024 of the control circuit 104 sets the charging pulse width modulation signal C to a high potential and the discharging pulse width modulation signal D to a low potential. In the discharging mode DM of the first positive half-cycle signal 1P, the discharging mode DM of the first negative half-cycle signal 1N, the discharging mode DM of the second positive half-cycle signal 2P, and the discharging mode DM of the second negative half-cycle signal 2N, the control signal generation circuit 1024 of the control circuit 104 sets the charging pulse width modulation signal C to a low potential and the discharging pulse width modulation signal D to a high potential. In the first positive half-cycle signal 1P of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20 and in the second positive half-cycle signal 2P of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20, the control signal generation circuit 1024 of the control circuit 104 sets the positive half-cycle pulse width modulation signal P to a high potential and the negative half-cycle pulse width modulation signal N to a low potential. In the first negative half-cycle signal 1N of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20 and in the second negative half-cycle signal 2N of the first single-phase AC power supply AC1 of the three-phase AC input power supply 20, the control signal generation circuit 1024 of the control circuit 104 sets the positive half-cycle pulse width modulation signal P to a low potential and the negative half-cycle pulse width modulation signal N to a high potential. When the power measurement value (L) is low, the control signal generation circuit 1024 of the control circuit 104 sets the three bridge arm circuits to operate in the light load mode LL. When the power measurement value (L) is high, the control signal generation circuit 1024 of the control circuit 104 sets the three bridge arm circuits to operate in the heavy load mode HL.

[0103] The control circuit 104 disclosed herein can be a digital signal processor. Figure 1 and Figure 5In this embodiment, the control circuit 104 needs to output a total of eighteen pulse width modulation signals (i.e., signal channels) to control all eighteen switches. Therefore, the design of the control circuit 104 is relatively complex and expensive, belonging to a high-end digital signal processor. Figure 6 In this embodiment, for one bridge arm circuit, the control circuit 104 needs to output four pulse width modulation signals (i.e., the discharge pulse width modulation signal D, the charging pulse width modulation signal C, the positive half-cycle pulse width modulation signal P, and the negative half-cycle pulse width modulation signal N) and one GPIO signal (i.e., the power measurement value (L)) to control the six switches of one bridge arm circuit. Since the three bridge arm circuits can share the GPIO signal, the control circuit 104 only needs to output twelve pulse width modulation signals (4*3=12) plus one GPIO signal to control all eighteen switches of the three bridge arm circuits. Therefore, the design of the control circuit 104 is relatively simple and inexpensive, belonging to the low-to-mid-range digital signal processor category. Figure 6 The advantage of this embodiment is that it reduces the cost of the control circuit 104.

[0104] Please refer to Figure 8 This is a flowchart of the operation method of the AC-DC conversion circuit disclosed herein. The operation method of the AC-DC conversion circuit disclosed herein uses an AC-DC conversion circuit to generate a DC output voltage based on a three-phase AC input power supply. The AC-DC conversion circuit includes a power measurement circuit, a control circuit, and three bridge arm circuits. The control circuit is coupled to the power measurement circuit. Each bridge arm circuit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch.

[0105] The first switch includes a control terminal coupled to the control circuit, a first terminal coupled to a first output terminal via a first capacitor, and a second terminal. The second switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch, and a second terminal coupled to a first input inductor. The third switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the second switch and the first input inductor, and a second terminal. The fourth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch, and a second terminal coupled to the first output terminal via a second capacitor. The fifth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch, and a second terminal coupled to the first output terminal. The sixth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a second terminal coupled to the second terminal of the third switch and the first terminal of the fourth switch.

[0106] The operation method of this AC-DC conversion circuit includes the following steps:

[0107] Step S02: The power measurement circuit measures at least one of an input power and an output power to generate a power measurement value. Then, the AC-DC conversion circuit operation proceeds to step S04.

[0108] Step S04: The control circuit determines the power measurement value. When the power measurement value is less than a power threshold, the AC-DC conversion circuit operation method proceeds to step S06; when the power measurement value is greater than the power threshold, the AC-DC conversion circuit operation method proceeds to step S08.

[0109] Step S06: The control circuit sets the three bridge arm circuits to operate in a light-load mode. Step S06 specifically includes the following: In a first positive half-cycle signal of a first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch coupled to the first bridge arm circuit of the first single-phase AC power supply to be turned on, and sets the third switch and the fourth switch to be turned off; In a charging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned off, and sets the fifth switch to be turned on; In a discharging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fifth switch to be turned off. In a first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch and the second switch of the first bridge arm circuit to be off, and sets the third switch to be on; in a charging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be off, and sets the sixth switch to be on; in a discharging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be on, and sets the sixth switch to be off.

[0110] Step S08: The control circuit sets the three bridge arm circuits to operate in a heavy-load mode. Step S08 specifically includes the following: In a second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fourth switch to be turned off; In a charging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned off, and sets the third switch and the fifth switch to be turned on; In a discharging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned on, and sets the third switch and the fifth switch to be turned off. In a second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch of the first bridge arm circuit to be off, and sets the third switch and the fifth switch to be on; in a charging mode of the second negative half-cycle signal, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be on, and sets the fourth switch to be off; in a discharging mode of the second negative half-cycle signal, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be off, and sets the fourth switch to be on.

[0111] The phases of the first single-phase AC power supply, the second single-phase AC power supply, and the third single-phase AC power supply of the three-phase AC input power supply are 120 degrees apart, and the phases of the control signals of the three bridge arm circuits set by the control circuit are 120 degrees apart.

[0112] In one embodiment: when the input power is less than the power threshold, the power measurement circuit sets the power measurement value to a low potential, so that the control circuit sets the three bridge arm circuits to operate in the light load mode; when the input power is greater than or equal to the power threshold, the power measurement circuit sets the power measurement value to a high potential, so that the control circuit sets the three bridge arm circuits to operate in the heavy load mode.

[0113] In another embodiment: when the output power is less than the power threshold, the power measurement circuit sets the power measurement value to a low potential, so that the control circuit sets the three bridge arm circuits to operate in the light load mode; when the output power is greater than or equal to the power threshold, the power measurement circuit sets the power measurement value to a high potential, so that the control circuit sets the three bridge arm circuits to operate in the heavy load mode.

[0114] Furthermore, the AC-DC conversion circuit may also include a logic circuit that, based on a discharge pulse width modulation signal (D), a charging pulse width modulation signal (C), a positive half-cycle pulse width modulation signal (P), and a negative half-cycle pulse width modulation signal (N) generated by the control circuit, and based on the power measurement value (L), generates a first control signal (Q1), a second control signal (Q2), a third control signal (Q3), a fourth control signal (Q4), a fifth control signal (Q5), and a sixth control signal (Q6) to control the conduction states of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch of the first bridge arm circuit, respectively; wherein:

[0115] Q1 = P and D

[0116] Q2 = (L and C)orP

[0117] Q3 = (L and C)orN

[0118] Q4 = N and D

[0119] Q5=Q4 or(L and Q3)or(P and C)or(L and C)

[0120] Q6=Q1 or(L and Q2)or(N and C)or(L and C)

[0121] In the charging mode of the first positive half-cycle signal, the charging mode of the first negative half-cycle signal, the charging mode of the second positive half-cycle signal, and the charging mode of the second negative half-cycle signal, the control circuit sets the charging pulse width modulation signal (C) to a high potential and the discharging pulse width modulation signal (D) to a low potential; in the discharging mode of the first positive half-cycle signal, the discharging mode of the first negative half-cycle signal, the discharging mode of the second positive half-cycle signal, and the discharging mode of the second negative half-cycle signal, the control circuit sets the charging pulse width modulation signal (C) to a low potential and the discharging pulse width modulation signal (D) to a high potential; in the first positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply... In the second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the positive half-cycle pulse width modulation signal (P) to a high potential and the negative half-cycle pulse width modulation signal (N) to a low potential; in the first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply and in the second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the positive half-cycle pulse width modulation signal (P) to a low potential and the negative half-cycle pulse width modulation signal (N) to a high potential; when the power measurement value (L) is low, the control circuit sets the three bridge arm circuits to operate in the light load mode; when the power measurement value (L) is high, the control circuit sets the three bridge arm circuits to operate in the heavy load mode.

[0122] The remaining technical details of the AC-DC conversion circuit operation method disclosed herein are similar to those of the AC-DC conversion circuit 10 disclosed herein, and therefore will not be repeated here.

[0123] Although this disclosure has been described with reference to embodiments thereof, it should be understood that this disclosure is not limited to its details; various substitutions and modifications have been proposed in the foregoing description, and other substitutions and modifications will occur to those skilled in the art; therefore, all such substitutions and modifications are intended to be included within the scope of this disclosure.

Claims

1. An AC-DC converter circuit, characterized in that, Used to generate a DC output voltage based on a three-phase AC input power supply, including: A power measurement circuit for measuring at least one of an input power and an output power to generate a power measurement value; A control circuit is coupled to the power measurement circuit; as well as The three bridge arm circuits, each of which includes: A first switch includes a control terminal coupled to the control circuit, a first terminal coupled to a first output terminal via a first capacitor, and a second terminal; A second switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch, and a second terminal coupled to a first input inductor; A third switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the second switch, a first input inductor, and a second terminal; A fourth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch, and a second terminal coupled to the first output terminal via a second capacitor; A fifth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch, and a second terminal coupled to the first output terminal; as well as A sixth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a second terminal coupled to the second terminal of the third switch and the first terminal of the fourth switch. When the measured power value is less than a power threshold, the control circuit sets the three bridge arm circuits to operate in a light-load mode: In a first positive half-cycle signal of a first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch coupled to a first bridge arm circuit of the first single-phase AC power supply to be turned on, and sets the third switch and the fourth switch to be turned off; in a charging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned off, and sets the fifth switch to be turned on; in a discharging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fifth switch to be turned off. In a first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch and the second switch of the first bridge arm circuit to be off, and sets the third switch to be on; in a charging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be off, and sets the sixth switch to be on; in a discharging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be on, and sets the sixth switch to be off. When the measured power value exceeds the power threshold, the control circuit sets the three bridge arm circuits to operate in a heavy load mode. In a second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fourth switch to be turned off; in a charging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned off, and sets the third switch and the fifth switch to be turned on; in a discharging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned on, and sets the third switch and the fifth switch to be turned off. In a second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch of the first bridge arm circuit to be off, and sets the third switch and the fifth switch to be on; in a charging mode of the second negative half-cycle signal, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be on, and sets the fourth switch to be off; in a discharging mode of the second negative half-cycle signal, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be off, and sets the fourth switch to be on.

2. The AC-DC conversion circuit according to claim 1, characterized in that, The phase difference between the first single-phase AC power supply, the second single-phase AC power supply and the third single-phase AC power supply of the three-phase AC input power supply is 120 degrees, and the phase difference between the control signals of the three bridge arm circuits of the control circuit is 120 degrees.

3. The AC-DC conversion circuit according to claim 1, characterized in that, When the input power is less than the power threshold, the power measurement circuit sets the power measurement value to a low potential, causing the control circuit to set the three bridge arm circuits to operate in the light load mode; when the input power is greater than or equal to the power threshold, the power measurement circuit sets the power measurement value to a high potential, causing the control circuit to set the three bridge arm circuits to operate in the heavy load mode.

4. The AC-DC conversion circuit according to claim 1, characterized in that, When the output power is less than the power threshold, the power measurement circuit sets the power measurement value to a low potential, causing the control circuit to set the three bridge arm circuits to operate in the light load mode; when the output power is greater than or equal to the power threshold, the power measurement circuit sets the power measurement value to a high potential, causing the control circuit to set the three bridge arm circuits to operate in the heavy load mode.

5. The AC-DC conversion circuit according to claim 1, characterized in that, It also includes a logic circuit that, based on a discharge pulse width modulation signal (D), a charging pulse width modulation signal (C), a positive half-cycle pulse width modulation signal (P), and a negative half-cycle pulse width modulation signal (N) generated by the control circuit, and based on the power measurement value (L), generates a first control signal (Q1), a second control signal (Q2), a third control signal (Q3), a fourth control signal (Q4), a fifth control signal (Q5), and a sixth control signal (Q6) to control the conduction states of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch of the first bridge arm circuit, respectively; wherein: Q1 = P and D Q2 = (L and C)orP Q3 = (L and C)orN Q4 = N and D Q5=Q4 or(L and Q3)or(P and C)or(L and C) Q6=Q1 or(L and Q2)or(N and C)or(L and C) In the charging mode of the first positive half-cycle signal, the charging mode of the first negative half-cycle signal, the charging mode of the second positive half-cycle signal, and the charging mode of the second negative half-cycle signal, the control circuit sets the charging pulse width modulation signal (C) to a high potential and the discharging pulse width modulation signal (D) to a low potential; in the discharging mode of the first positive half-cycle signal, the discharging mode of the first negative half-cycle signal, the discharging mode of the second positive half-cycle signal, and the discharging mode of the second negative half-cycle signal, the control circuit sets the charging pulse width modulation signal (C) to a low potential and the discharging pulse width modulation signal (D) to a high potential; in the first positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply... In the second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the positive half-cycle pulse width modulation signal (P) to a high potential and the negative half-cycle pulse width modulation signal (N) to a low potential; in the first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply and in the second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the positive half-cycle pulse width modulation signal (P) to a low potential and the negative half-cycle pulse width modulation signal (N) to a high potential; when the power measurement value (L) is low, the control circuit sets the three bridge arm circuits to operate in the light load mode; when the power measurement value (L) is high, the control circuit sets the three bridge arm circuits to operate in the heavy load mode.

6. A method for operating an AC-DC conversion circuit, characterized in that, An AC-DC converter circuit generates a DC output voltage based on a three-phase AC input power supply. The AC-DC converter circuit includes a power measurement circuit, a control circuit, and three bridge arm circuits. The control circuit is coupled to the power measurement circuit. Each bridge arm circuit includes: A first switch includes a control terminal coupled to the control circuit, a first terminal coupled to a first output terminal via a first capacitor, and a second terminal; A second switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch, and a second terminal coupled to a first input inductor; A third switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the second switch, a first input inductor, and a second terminal; A fourth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the third switch, and a second terminal coupled to the first output terminal via a second capacitor; A fifth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the first switch and the first terminal of the second switch, and a second terminal coupled to the first output terminal; as well as A sixth switch includes a control terminal coupled to the control circuit, a first terminal coupled to the second terminal of the fifth switch and the first output terminal, and a second terminal coupled to the second terminal of the third switch and the first terminal of the fourth switch. The operation method of this AC-DC converter circuit includes: The power measurement circuit measures at least one of an input power and an output power to generate a power measurement value. When the measured power value is less than a power threshold, the control circuit sets the three bridge arm circuits to operate in a light-load mode: In a first positive half-cycle signal of a first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch coupled to a first bridge arm circuit of the first single-phase AC power supply to be turned on, and sets the third switch and the fourth switch to be turned off; in a charging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned off, and sets the fifth switch to be turned on; in a discharging mode of the first positive half-cycle signal, the control circuit sets the first switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fifth switch to be turned off. In a first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch and the second switch of the first bridge arm circuit to be off, and sets the third switch to be on; in a charging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be off, and sets the sixth switch to be on; in a discharging mode of the first negative half-cycle signal, the control circuit sets the fourth switch and the fifth switch of the first bridge arm circuit to be on, and sets the sixth switch to be off. When the measured power value exceeds the power threshold, the control circuit sets the three bridge arm circuits to operate in a heavy load mode: In a second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be turned on, and sets the fourth switch to be turned off; in a charging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned off, and sets the third switch and the fifth switch to be turned on; in a discharging mode of the second positive half-cycle signal, the control circuit sets the first switch of the first bridge arm circuit to be turned on, and sets the third switch and the fifth switch to be turned off. In a second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the first switch of the first bridge arm circuit to be off, and sets the third switch and the fifth switch to be on; in a charging mode of the second negative half-cycle signal, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be on, and sets the fourth switch to be off; in a discharging mode of the second negative half-cycle signal, the control circuit sets the second switch and the sixth switch of the first bridge arm circuit to be off, and sets the fourth switch to be on.

7. The AC-DC conversion circuit operation method according to claim 6, characterized in that, The phase difference between the first single-phase AC power supply, the second single-phase AC power supply and the third single-phase AC power supply of the three-phase AC input power supply is 120 degrees, and the phase difference between the control signals of the three bridge arm circuits of the control circuit is 120 degrees.

8. The AC-DC conversion circuit operation method according to claim 6, characterized in that, When the input power is less than the power threshold, the power measurement circuit sets the power measurement value to a low potential, causing the control circuit to set the three bridge arm circuits to operate in the light load mode; when the input power is greater than or equal to the power threshold, the power measurement circuit sets the power measurement value to a high potential, causing the control circuit to set the three bridge arm circuits to operate in the heavy load mode.

9. The method for operating the AC-DC conversion circuit according to claim 6, characterized in that, When the output power is less than the power threshold, the power measurement circuit sets the power measurement value to a low potential, causing the control circuit to set the three bridge arm circuits to operate in the light load mode; when the output power is greater than or equal to the power threshold, the power measurement circuit sets the power measurement value to a high potential, causing the control circuit to set the three bridge arm circuits to operate in the heavy load mode.

10. The method for operating the AC-DC conversion circuit according to claim 6, characterized in that, The AC-DC conversion circuit further includes a logic circuit that, based on a discharge pulse width modulation signal (D), a charging pulse width modulation signal (C), a positive half-cycle pulse width modulation signal (P), and a negative half-cycle pulse width modulation signal (N) generated by the control circuit, and based on the power measurement value (L), generates a first control signal (Q1), a second control signal (Q2), a third control signal (Q3), a fourth control signal (Q4), a fifth control signal (Q5), and a sixth control signal (Q6) to control the conduction states of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch of the first bridge arm circuit, respectively; wherein: Q1 = P and D Q2 = (L and C)orP Q3 = (L and C)orN Q4 = N and D Q5=Q4 or(L and Q3)or(P and C)or(L and C) Q6=Q1 or(L and Q2)or(N and C)or(L and C) In the charging mode of the first positive half-cycle signal, the charging mode of the first negative half-cycle signal, the charging mode of the second positive half-cycle signal, and the charging mode of the second negative half-cycle signal, the control circuit sets the charging pulse width modulation signal (C) to a high potential and the discharging pulse width modulation signal (D) to a low potential; in the discharging mode of the first positive half-cycle signal, the discharging mode of the first negative half-cycle signal, the discharging mode of the second positive half-cycle signal, and the discharging mode of the second negative half-cycle signal, the control circuit sets the charging pulse width modulation signal (C) to a low potential and the discharging pulse width modulation signal (D) to a high potential; in the three-phase AC input power supply... In the first positive half-cycle signal of the first single-phase AC power supply and in the second positive half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the positive half-cycle pulse width modulation signal (P) to a high potential and the negative half-cycle pulse width modulation signal (N) to a low potential; in the first negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply and in the second negative half-cycle signal of the first single-phase AC power supply of the three-phase AC input power supply, the control circuit sets the positive half-cycle pulse width modulation signal (P) to a low potential and the negative half-cycle pulse width modulation signal (N) to a high potential; when the power measurement value (L) is at a low potential, the control circuit sets the three bridge arm circuits to operate in the light load mode; When the power measurement value (L) is high, the control circuit sets the three bridge arm circuits to operate in the heavy load mode.

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