AC-DC Power Conversion System with High Voltage Gain

Abstract

This case provides an AC-DC power conversion system, which controls its duty cycle according to the required input-output gain to obtain the characteristic of high voltage gain. The AC-DC power conversion system includes an AC stage, first and second inductors, first and second voltage multiplier stages, a totem-pole rectifier stage, and a DC stage connected in parallel to the totem-pole rectifier stage. Each voltage multiplier stage includes first, second, and third terminals. The first terminal of the AC stage is connected to the first terminal of each voltage multiplier stage through the first inductor, and the first terminal of the AC stage is connected to the third terminal of each voltage multiplier stage through the second inductor. The totem-pole rectifier stage includes first and second terminals. The first terminal of the totem-pole rectifier stage is connected to the second terminal of the first voltage multiplier stage, and the second terminal of the totem-pole rectifier stage is connected to the second terminal of the second voltage multiplier stage.

Description

Technical Field

[0001] This case relates to a power conversion system, especially a bidirectional AC-DC power conversion system with high voltage gain. Background Art

[0002] AC-DC power conversion systems are widely used in many applications, such as variable speed drives for electric vehicles, power supplies with switchable modes, and battery chargers. The construction of AC-DC converters is based on uncontrolled diode rectifiers that allow power to flow in only one direction and thyristor rectifiers that allow power to flow bidirectionally. Current rectifiers have been developed to overcome power quality problems caused by highly distorted currents and low power factors in the AC grid. Rectifiers operate at line frequency, resulting in larger input filter components and slower dynamic changes. Today's power semiconductor devices (such as MOSFETs (metal-oxide-semiconductor field-effect transistors) and IGBTs (insulated-gate bipolar transistors)) have made it possible to improve the efficiency of AC-DC power conversion. For example, single-switch boost power converters have been widely used and have an inherent power conversion stage that helps the power converter meet power quality standards. However, even though active PFC (power-factor correction) can improve the performance of single-switch boost rectifiers, high power losses still occur due to the conduction losses of the input diode rectifier. For this reason, many significant studies have been conducted on converters with higher efficiency due to the absence of input diodes. This is reflected in the PFC circuit as topologies with fewer switch legs, which is also the prior art in the field of AC-DC converters.

[0003] Figure 1 The totem-pole boost converter 100 is shown, which is an example of a PFC topology with fewer switch legs. As Figure 1As shown, the totem-pole boost converter 100 includes two half-bridge arms operating at line frequency. The components in each half-bridge arm are connected in a totem-pole structure. One half-bridge arm is formed by high-frequency switches S1 and S2, and the other half-bridge arm is formed by diodes D1 and D2. At any point in time, there are only two power semiconductor devices in the current path, rather than three power semiconductor devices. Therefore, the totem-pole topology with fewer switching arms can effectively reduce the conduction loss of the traditional boost PFC circuit. In the prior art, IGBTs with fast-recovery antiparallel diodes can be used to implement the totem-pole PFC circuit. Conversely, due to the severe reverse-recovery loss of the antiparallel diodes in silicon MOSFETs, silicon MOSFETs cannot yet be used in the totem-pole PFC circuit.

[0004] Since wide-bandgap devices have negligible or even no reverse-recovery loss, wide-bandgap devices enable the totem-pole structure to be more widely used in AC-DC converters. In an AC-DC converter, since the totem-pole DC output voltage is greater than the peak AC input voltage, the minimum voltage gain is limited to 1. In an application environment with extremely low input voltage, the controllable switches S1 and S2 must operate at a very high duty cycle to regulate the DC output voltage V O , resulting in an increase in conduction loss and a decrease in circuit efficiency. Therefore, a PFC circuit with a high voltage gain is indeed required at present. In addition, to Figure 1 operate the totem-pole boost converter 100 in a bidirectional power flow mode, the diodes D1 and D2 in one half-bridge arm need to be replaced with controllable switches (i.e., as synchronous rectifiers). Furthermore, some applications require a relatively high gain for the regulated DC output voltage, especially when the PFC circuit operates under conditions of low DC input voltage. Figure 2 FIG. shows an AC-DC boost converter 200 that can obtain a relatively high voltage gain, which is an example of a half-bridge PFC topology. The advantage of the AC-DC boost converter 200 is that there is only one of the switches S1 and S2 in the input current path at any point in time, so the conduction loss can be further reduced. In an application environment with low input voltage, another advantage of the AC-DC boost converter 200 is that the DC output voltage is at least twice the peak AC output voltage, and the AC-DC boost converter 200 has a voltage-doubling characteristic, which cannot be obtained by the totem-pole PFC topology. However, the output capacitor of the AC-DC boost converter 200 is charged during one half-cycle of the input line voltage and discharged during the other half-cycle of the input line voltage. Therefore, the output capacitor of the AC-DC boost converter 200 will be much larger than Figure 1The output capacitor of the totem-pole PFC circuit or the traditional boost PFC converter is an obvious drawback of the AC-DC boost converter 200. The long charge and discharge cycles require the AC-DC boost converter 200 to store more energy to suppress the fluctuations near its DC voltage.

[0005] Figure 3 Fig. shows a boost DC-DC power converter 300 including two switches and two inductors, which is an example of a DC-DC voltage-doubling boost topology. The DC-DC power converter 300 utilizes a stacked structure to obtain a DC output voltage gain. Different from Figure 2 the totem-pole structure in Figure 3 the DC-DC converter 300 of B the capacitors C and C Figure 3 are charged and discharged based on the switching cycle, which can significantly reduce the energy storage requirement and the output capacitor value, where the output capacitor value is used to suppress the DC output voltage ripple. By interleaving the switches S1 and S2, the input current ripple can be eliminated, thereby greatly reducing the required size of the input filter. However,

[0006] In the traditional boost PFC converter, its duty cycle needs to be maximized to obtain a high voltage gain between the AC input voltage and the DC output voltage. Therefore, the switch-on time also reaches the maximum, which increases the conduction loss and reduces the converter efficiency. Therefore, how to develop a power conversion system that can provide high power conversion efficiency and high voltage gain through a multi-stage circuit is an urgent need at present. SUMMARY OF THE INVENTION

[0007] According to an embodiment of the present invention, the AC-DC power conversion system controls its duty cycle according to the required input-output gain to obtain the characteristic of high voltage gain. And in any transmission direction between the AC side and the DC side, the AC-DC power conversion system can achieve seamless power transmission. The AC-DC power conversion system of this embodiment can be used as a bidirectional AC-DC power conversion system.

[0008] An embodiment of the present case provides an AC-DC power conversion system, including an AC stage, first and second inductors, first and second voltage multiplier stages, a totem pole rectifier stage, and a DC stage. The DC stage is coupled in parallel to the totem pole rectifier stage. The AC stage includes first and second terminals. Each voltage multiplier stage includes a first terminal, a second terminal, and a third terminal. The first terminal of the AC stage is coupled to the first terminal of each voltage multiplier stage via the first inductor, and the first terminal of the AC stage is coupled to the third terminal of each voltage multiplier stage via the second inductor. The totem pole rectifier stage includes first and second terminals, wherein the first terminal of the totem pole rectifier stage is coupled to the second terminal of the first voltage multiplier stage, and the second terminal of the totem pole rectifier stage is coupled to the second terminal of the second voltage multiplier stage.

[0009] In some embodiments, the totem pole filter stage includes first and second half-bridge arms, and each half-bridge arm includes first and second components connected in series to a common terminal. The second terminal of the AC stage is coupled to the common terminal of the second half-bridge arm, and the common terminal of the first half-bridge arm is coupled to the third terminal of each voltage multiplier stage.

[0010] In some embodiments, each voltage multiplier stage includes a capacitor and first, second, and third switches. The first and second switches of the voltage multiplier stage are connected in series between the first and second terminals of the voltage multiplier stage. The first and second switches of the voltage multiplier stage are connected to a common terminal, and the third switch and the capacitor of the voltage multiplier stage are connected in series between the common terminal and the third terminal of the voltage multiplier stage.

[0011] In some embodiments, the bidirectional AC-DC power conversion system includes two voltage multiplier stages to amplify the totem pole rectifier stage or an inverter configuration connected to two inductors. Without the need for a wide range of duty cycle variations, the AC-DC power conversion system performs active PFC when electric energy is transmitted from the AC terminal to the DC terminal, and obtains the characteristics of high voltage gain and strengthens the elimination of current ripple. When electric energy is transmitted from the DC terminal to the AC terminal, the AC-DC power conversion system can achieve sine wave voltage or current inversion. The characteristics of high voltage gain enable the AC-DC power conversion system to provide a low voltage to the AC terminal during the period when electric energy is transmitted from the DC terminal to the AC terminal. Therefore, compared with traditional inverters, the AC-DC power conversion system of the present case can be particularly suitable for application environments with low AC voltages.

[0012] According to an embodiment of the present case, each voltage multiplier stage includes a pre-charge and balance resistor circuit to equalize the voltage on the energy storage capacitor of the voltage multiplier stage before the switch of the voltage multiplier stage is actuated, thereby ensuring the safe operation of the AC-DC power conversion system.

[0013] In high-power applications, a bidirectional AC-DC power conversion system may include multiple voltage multiplier stages to form relatively symmetric arms of a suitable number of totem-pole rectifiers, thereby dispersing the voltage and current stresses on the switches, inductors, and capacitors of the bidirectional AC-DC power conversion system. In some embodiments, each relatively symmetric arm includes two voltage multiplier stages and an inductor. In such embodiments, the relatively symmetric arm operates together with a single totem-pole rectifier phase arm to form a synchronous rectifier. In any relatively symmetric arm, each voltage multiplier stage includes a first end, a second end, a third end, a first switch, a second switch, a third switch, and a energy storage capacitor. The first and second switches are serially connected between the first and second ends, and the first and second switches are connected to a common end. The third switch and the energy storage capacitor of the voltage multiplier stage are serially connected between the common end and the third end of the voltage multiplier stage. The first end of each voltage multiplier stage of the relatively symmetric arm is connected to the AC end via a corresponding inductor, and the third end of each voltage multiplier stage of the relatively symmetric arm is connected to another relatively symmetric arm or a totem-pole phase arm via another inductor.

[0014] Another embodiment of the present case provides an AC-DC power conversion system, including an AC stage, first, second, and third inductors, first and second voltage multiplier stages, a totem-pole rectifier stage, and a DC stage. The DC stage is connected in parallel to the totem-pole rectifier stage. The AC stage includes a switching element, a first end, a second end, a third end, and a neutral end. Each voltage multiplier stage includes a first, a second, and a third end. The totem-pole rectifier stage includes first and second half-bridge arms. Each half-bridge arm is connected between the second end of the first voltage multiplier stage and the second end of the second voltage multiplier stage, and each half-bridge arm includes a first and a second element serially connected to a common end. The DC stage includes a first and a second capacitor serially connected to a common end.

[0015] In some embodiments, the switching element has first and second configurations. In the first configuration, the first end of the AC stage is coupled to the first end of each voltage multiplier stage via the first inductor, the first end of the AC stage is coupled to the third end of each voltage multiplier stage and the common end of the first half-bridge arm via the second inductor, and the neutral end is coupled to the common end of the second half-bridge arm. In the second configuration, the first end of the AC stage is coupled to the first end of each voltage multiplier stage via the first inductor, the second end of the AC stage is coupled to the common end of the first half-bridge arm via the second inductor, the third end of the AC stage is coupled to the common end of the second half-bridge arm via the third inductor, and the neutral end is coupled to the common end of the DC stage.

[0016] According to another embodiment of the present case, the bidirectional AC-DC power conversion system may include a relay switch, which is switchably connected to a single-phase AC terminal or a three-phase AC terminal. This flexibility enables the bidirectional AC-DC power conversion system to operate on single-phase and three-phase power supplies. The bidirectional switches of the energy storage capacitors connected in series to each voltage multiplier stage of the symmetrical bridge arms can further improve the performance of the power conversion system. Through the following detailed description and the corresponding diagrams, the content of the present case can be more easily understood. Description of the Drawings

[0017] Figure 1 The circuit structure of the totem pole boost converter 100 is shown, which is an example of a PFC topology with fewer switch arms.

[0018] Figure 2 The circuit structure of the AC-DC boost converter 200 is shown, which is an example of a half-bridge PFC topology that can obtain a high voltage gain.

[0019] Figure 3 The circuit structure of the boost DC-DC power converter 300 with two switches and two inductors is shown, which is a DC-DC voltage multiplier boost topology.

[0020] Figure 4 The circuit structure schematic diagram of the AC-DC power conversion system 400 with high voltage gain according to an embodiment of the present case.

[0021] Figure 5 The circuit structure schematic diagram of the AC-DC power conversion system 500 according to another embodiment of the present case.

[0022] Figure 6 For controlling Figure 5 The timing schematic diagram of the switching actuation control signals of the switches S3, S4 and S of the AC-DC power conversion system 500 within a period, where within this period, the input voltage V A2 is in the positive half cycle, and the magnitude of the input voltage V AC is less than one quarter of the output voltage V AC and O is less than one quarter of the output voltage V.

[0023] Figure 7 For Figure 5 The topology schematic diagram of the AC-DC power conversion system 500 during the time period from t0 to t1 or during the time period from t2 to t3, showing the current flow direction during the time period from t0 to t1 or during the time period from t2 to t3.

[0024] Figure 8 For Figure 5 The topology schematic diagram of the AC-DC power conversion system 500 during the time period from t1 to t2.

[0025] Figure 9 The Figure 5 topological schematic diagram of the AC-DC power conversion system 500 during the time period from t3 to t4.

[0026] Figure 10 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 Figure 6 under the operating conditions of

[0027] Figure 11 For controlling Figure 5 the switches S3, S4 and S of the AC-DC power conversion system 500 A2 The timing schematic diagram of the switch actuation control signals during a period, wherein during this period, the input voltage V AC is in the positive half-cycle, and the magnitude of the input voltage V AC is greater than one-fourth of the output voltage V O .

[0028] Figure 12 The Figure 5 topological schematic diagram of the AC-DC power conversion system 500 during the time period from t1 to t2 or during the time period from t3 to t4.

[0029] Figure 13 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 Figure 11 under the operating conditions of

[0030] Figure 14 For controlling Figure 5 the switches S1, S2 and S of the AC-DC power conversion system 500 A1 The timing schematic diagram of the switch actuation control signals during a period, wherein during this period, the input voltage V AC is in the negative half-cycle, and the magnitude of the input voltage V AC is less than one-fourth of the output voltage V O .

[0031] Figure 15 The Figure 5 topological schematic diagram of the AC-DC power conversion system 500 under the operating conditions of Figure 14 during the time period from t0 to t1 or during the time period from t2 to t3.

[0032] Figure 16 The Figure 5 topological schematic diagram of the AC-DC power conversion system 500 under the operating conditions of Figure 14 during the time period from t1 to t2.

[0033] Figure 17 The Figure 5 AC-DC power conversion system 500 at Figure 14 operating conditions during the time period from t3 to t4.

[0034] Figure 18 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 at Figure 14 operating conditions.

[0035] Figure 19 For controlling Figure 5 the switches S1, S2 and S of the AC-DC power conversion system 500 A1 of the switch actuation control signals during a period, wherein during this period, the input voltage V AC is in the negative half cycle, and the magnitude of the input voltage V AC is greater than one quarter of the output voltage V O .

[0036] Figure 20 The Figure 5 AC-DC power conversion system 500 at Figure 19 operating conditions during the time period from t1 to t2 or during the time period from t3 to t4.

[0037] Figure 21 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 at Figure 19 operating conditions.

[0038] Figure 22 The circuit structure diagram of the bidirectional AC-DC power conversion system 2200 according to another embodiment of the present case, wherein the AC side output voltage V DC is provided based on the DC side voltage V AC .

[0039] Figure 23 For controlling Figure 22 the switches S1 and S2 of the bidirectional AC-DC power conversion system 2200 of the switch actuation control signals during a period, wherein during this period, the output voltage V AC is in the positive half cycle, and the magnitude of the input DC voltage V DC is greater than one quarter of the output AC voltage V AC .

[0040] Figure 24 The Figure 22 bidirectional AC-DC power conversion system 2200 at Figure 23 operating conditions during the time period from t0 to t1.

[0041] Figure 25 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 23 the topological schematic diagram during the period from time t1 to t2 or from time t3 to t4 under the operating conditions of

[0042] Figure 26 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 23 the topological schematic diagram during the period from time t2 to t3 under the operating conditions of

[0043] Figure 27 For controlling Figure 22 the two-way AC-DC power conversion system 2200, the timing schematic diagram of the switch actuation control signals of switches S1 and S2 within a period, where during this period, the output AC voltage V AC is in the positive half-cycle, the magnitude of the output AC voltage V AC is between one-quarter and one-half of the input voltage V DC and the energy is transmitted from the input voltage source V DC to the output voltage V AC .

[0044] Figure 28 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 27 the topological schematic diagram during the period from time t0 to t1 or from time t2 to t3 under the operating conditions of

[0045] Figure 29 For controlling Figure 22 the two-way AC-DC power conversion system 2200, the timing schematic diagram of the switch actuation control signals of switches S3 and S4 within a period, where during this period, the output voltage V AC is in the negative half-cycle, the magnitude of the output AC voltage V AC is less than one-quarter of the input DC voltage V DC .

[0046] Figure 30 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 29 the topological schematic diagram during the period from time t0 to t1 under the operating conditions of

[0047] Figure 31 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 29 the topological schematic diagram during the period from time t1 to t2 or from time t3 to t4 under the operating conditions of

[0048] Figure 32 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 29 the topological schematic diagram during the time period from t2 to t3 under the operating conditions of

[0049] Figure 33 For controlling Figure 22 the switch actuation control signals of switches S3 and S4 of the two-way AC-DC power conversion system 2200 within a period, wherein during this period, the output AC voltage V AC is in the negative half-cycle, the magnitude of the output AC voltage V AC is between one-quarter and one-half of the input voltage V DC and the energy is transferred from the input voltage source V DC to the output voltage V AC .

[0050] Figure 34 For Figure 22 the two-way AC-DC power conversion system 2200 at Figure 33 the topological schematic diagram during the time period from t0 to t1 or during the time period from t2 to t3 under the operating conditions of

[0051] Figure 35 For the circuit structure schematic diagram of the two-way AC-DC power conversion system 3500 according to another embodiment of the present case, wherein the two-way AC-DC power conversion system 3500 includes pre-charge resistors R PRE and voltage balancing resistors R BAL in both its voltage multiplier stages 3501a and 3501b.

[0052] Figure 36 For the circuit structure schematic diagram of the two-way AC-DC power conversion system 3600 according to another embodiment of the present case, wherein the two-way AC-DC power conversion system 3600 includes two symmetrical bridge arms, one of which is formed by voltage multiplier stages 3601a and 3601b, and the other is formed by voltage multiplier stages 3601c and 3601d.

[0053] Figure 37 For controlling Figure 36 the switch actuation control signals of switches S3, S4, S7 and S8 of the two-way AC-DC power conversion system 3600 within a period, wherein during this period, the input AC voltage V AC is in the positive half-cycle, the magnitude of the input AC voltage V AC is less than one-quarter of the output voltage V DC and the energy is from the input AC voltage source V ACis transmitted to the output voltage V DC .

[0054] Figure 38 shows Figure 36 the ideal voltage and current waveforms of the components in the AC-DC power conversion system 3600 of Figure 37 under the operating conditions of

[0055] Figure 39 is for controlling Figure 36 the timing diagram of the switch actuation control signals of switches S3, S4, S7, and S8 in the bidirectional AC-DC power conversion system 3600 during a period, where during this period, the input voltage V AC is in the positive half-cycle, the magnitude of the input AC voltage V AC is greater than one-fourth of the output DC voltage V DC , and the energy is transmitted from the input AC voltage source V AC to the output DC voltage V DC .

[0056] Figure 40 shows Figure 36 the ideal voltage and current waveforms of the components in the AC-DC power conversion system 3600 of Figure 39 under the operating conditions of

[0057] Figure 41 is for controlling Figure 36 the timing diagram of the switch actuation control signals of switches S1, S2, S5, and S6 in the bidirectional AC-DC power conversion system 3600 during a period, where during this period, the input AC voltage V AC is in the negative half-cycle, the magnitude of the input AC voltage V AC is less than one-fourth of the output voltage V DC , and the energy is transmitted from the input AC voltage source V AC to the output DC voltage V DC .

[0058] Figure 42 shows Figure 36 the ideal voltage and current waveforms of the components in the AC-DC power conversion system 3600 of Figure 41 under the operating conditions of

[0059] Figure 43 is for controlling Figure 36 the timing diagram of the switch actuation control signals of switches S1, S2, S5, and S6 in the bidirectional AC-DC power conversion system 3600 during a period, where during this period, the input voltage V AC is in the negative half-cycle, the magnitude of the input AC voltage V ACis greater than the output DC voltage V DC by a quarter, and the energy is supplied by the input AC voltage source V AC is transferred to the output DC voltage V DC .

[0060] Figure 44 shows Figure 36 the ideal voltage and current waveforms of the components in the AC-DC power conversion system 3600 of Figure 43 under the operating conditions of

[0061] Figure 45 is a timing diagram of the switch actuation control signals for the switches S1, S2, S5, and S6 that control the Figure 36 bidirectional AC-DC power conversion system 3600 during a period in which the output voltage V AC is in the positive half-cycle, the magnitude of the output AC voltage V AC is greater than a quarter of the input DC voltage V DC and the energy is transferred from the input DC voltage source V DC to the output AC voltage V AC .

[0062] Figure 46 is a timing diagram of the switch actuation control signals for the switches S1 and S2 that control the Figure 36 bidirectional AC-DC power conversion system 3600 during a period in which the output AC voltage V AC is in the positive half-cycle, the magnitude of the output AC voltage V AC is greater than a quarter of the input voltage V DC and the energy is transferred from the input DC voltage source V DC to the output AC voltage V AC .

[0063] Figure 47 is a timing diagram of the switch actuation control signals for the switches S3, S4, S7, and S8 that control the Figure 36 bidirectional AC-DC power conversion system 3600 during a period in which the output voltage V AC is in the negative half-cycle, the magnitude of the output AC voltage V AC is less than a quarter of the input DC voltage V DC and the energy is transferred from the input DC voltage source V DC to the output AC voltage V AC .

[0064] Figure 48 is a timing diagram of the switch actuation control signals for the switches that control the Figure 36Timing diagram of the switching actuation control signals of switches S3 and S4 in the bidirectional AC-DC power conversion system 3600 within a period, where during this period, the output AC voltage V AC is in the negative half-cycle, and the magnitude of the output AC voltage V AC is greater than one-fourth of the input voltage V DC , and the energy is transferred from the input DC voltage source V DC to the output AC voltage V AC .

[0065] Figure 49 Schematic diagram of the circuit structure of the bidirectional AC-DC power conversion system 4900 according to another embodiment of the present case, where the bidirectional AC-DC power conversion system 4900 includes three symmetrical bridge arms formed by voltage multiplier stages 4901a to 4901f.

[0066] Figure 50 Schematic diagram of the circuit structure of the AC-DC power conversion system 5000 according to another embodiment of the present case, where the AC-DC power conversion system 5000 includes M symmetrical bridge arms.

[0067] Figure 51 Schematic diagram of the circuit structure of the bidirectional AC-DC power conversion system 5100 according to another embodiment of the present case.

[0068] Figure 52 Shows the circuit architecture of the bidirectional AC-DC power conversion system 5100, where the relay switch 5101 is in the "up" position, enabling the bidirectional AC-DC power conversion system 5100 to receive a single-phase AC voltage V AC .

[0069] Figure 53 Shows the circuit architecture of the bidirectional AC-DC power conversion system 5100, where the relay switch 5101 is in the "down" position, enabling the bidirectional AC-DC power conversion system 5100 to receive a three-phase AC voltage V AC , where the three phases of the three-phase AC voltage V AC are respectively coupled between port A and N, between port B and N, and between port C and N.

[0070] Figure 54 Schematic diagram of the circuit structure of the bidirectional AC-DC power conversion system 5400 according to another embodiment of the present case.

[0071] Figure 55 Shows the circuit architecture of the bidirectional AC-DC power conversion system 5400, where the relay switch 5101 is in the "up" position, enabling the bidirectional AC-DC power conversion system 5400 to receive a single-phase AC voltage V AC。

[0072] Figure 56 Shows the circuit architecture of the bidirectional AC-DC power conversion system 5400, where the relay switch 5101 is in the "down" position, enabling the bidirectional AC-DC power conversion system 5400 to receive a three-phase AC voltage V AC , where the three phases of the three-phase AC voltage V AC are respectively coupled between port A and N, between port B and N, and between port C and N.

[0073] Among them, the reference numerals are explained as follows:

[0074] 100: Totem pole boost converter

[0075] 200: AC-DC boost converter

[0076] 300: DC-DC power converter

[0077] 400, 500: AC-DC power conversion system

[0078] 2200, 3500, 3600, 4900, 5000, 5100, 5400: Bidirectional AC-DC power conversion system

[0079] L1, L2, L3, L M : Inductor

[0080] 401a, 401b, 501a, 501b, 3501a, 3501b, 3601a, 3601b, 3601c, 3601d, 4901a, 4901b, 4901c, 4901d, 4901e, 4901f, 5401a, 5401b: Voltage multiplier stage

[0081] 402, 502: Totem pole rectifier stage

[0082] 403, 503: DC stage

[0083] t0, t1, t2, t3, t4: Time

[0084] S1, S2, S3, S4, S5, S6, S7, S8, S9, S 10 , S 11 , S 12 , S 4M-3 , S 4M-2 , S 4M-1 , S 4M , S A1 , S A2 , S P , S P1 , S P2 , SP3 , S PM , S N , S N1 , S N2 , S N3 , S NM : Switch

[0085] D1, D2: Diode

[0086] C, C B : Capacitor

[0087] C1, C2, C3, C4, C5, C6, C 2M-1 , C 4M-1 : Energy storage capacitor

[0088] C O1 , C O2 : Output capacitor

[0089] V O : Output voltage

[0090] V AC : AC voltage

[0091] V DC : DC voltage

[0092] R: Load

[0093] D: Duty cycle

[0094] T S : Switching period

[0095] i L1 , i L2 : Inductor current

[0096] V S1 , V S2 , V S3 , V S4 , V S5 , V S6 , V S7 , V S8 , V SA1 , V SA2 , V C1 , V C2 , V C3 , V C4 , V C5 , V C6 , V C2M-1 , V C4M-1 : Voltage

[0097] i S1 , i S2 , i S3 , iS4 , i S5 , i S6 , i S7 , i S8 , i SA1 , i SA2 : Current

[0098] R PRE : Pre-charge resistor

[0099] R BAL : Voltage balancing resistor

[0100] 5101: Relay switch

[0101] A, B, C, N: Ports Detailed implementation manners

[0102] Some typical embodiments embodying the features and advantages of this case will be described in detail in the following description. It should be understood that this case can have various changes in different aspects, all of which do not depart from the scope of this case, and the descriptions and illustrations therein are essentially for illustrative purposes rather than for limiting this case.

[0103] According to an embodiment of this case, in a bidirectional power conversion system, when the system transfers energy from an AC input voltage to a DC output voltage, the bidirectional power conversion system can provide power factor correction for the AC input signal or power supply, and at the same time can provide a high input-output voltage gain. When the system transfers energy from a DC input voltage to an AC output voltage, the bidirectional power conversion system can provide a sinusoidal voltage or current as the AC output signal, and at the same time can provide a high input-output voltage gain. Due to the high voltage gain characteristic of the power conversion system of this case, it can be applied to energy transfer between a high-voltage DC terminal and a low-voltage AC terminal.

[0104] In some embodiments, a PFC power conversion system with high gain includes a totem pole rectification stage, where the totem pole rectification stage is coupled to two voltage multiplier stages. Each voltage multiplier stage can include two series-connected switches, a line frequency switch, and a storage capacitor, where the switches operate at the operating frequency of the power conversion system, and the line frequency switch operates at the line frequency of the AC voltage source. The line frequency switch is coupled between the storage capacitor and the common terminal between the two series-connected switches. The two voltage multiplier stages share a common boost inductor, where the common boost inductor is coupled between the AC voltage source and the connection point of the two voltage multiplier stages. The connection point of the storage capacitors of the two voltage multiplier stages is coupled to the common terminal between the synchronous rectifiers of the totem pole rectification stage.

[0105] In some other embodiments, the power conversion system of this case includes a plurality of symmetric bridge arms, and each bridge arm includes two voltage multiplier stages, operating in a staggered manner in high-power applications.

[0106] According to some embodiments of the present case, Figures 4 to 21 shows various high-gain PFC or inverter power conversion systems, as well as waveforms of specific voltage, current, and switch actuation control signals during their operation. When a DC source is coupled to the DC side and an AC load is coupled to the AC side, the high-gain PFC power conversion system of the present case can also operate as a DC-AC inverter. Furthermore, due to its high-gain characteristics, the high-gain PFC power conversion system of the present case can output a low AC voltage after adjustment upon receiving a high DC voltage.

[0107] According to some embodiments of the present case, Figures 22 to 50 shows various high-gain bidirectional PFC or inverter power conversion systems, as well as waveforms of specific voltage, current, and switch actuation control signals during their operation.

[0108] Figures 51 to 56 The various high-gain bidirectional PFC or inverter power conversion systems shown, where each power conversion system can additionally utilize a relay switch to operate switchably on a single-phase AC voltage source and / or a three-phase AC voltage source. The high-gain power conversion system of the present case is applicable to applications operating between a DC battery and an AC voltage source (including single-phase and three-phase).

[0109] Figure 4 is a schematic circuit diagram of an AC-DC power conversion system 400 with high voltage gain according to an embodiment of the present case. As Figure 4 shown, the AC-DC power conversion system 400 includes an AC stage, an inductor L1, voltage multiplier stages 401a and 401b, a totem pole rectifier stage 402, and a DC stage 403. The DC stage 403 includes an output stage. The AC stage includes a first end and a second end. The AC-DC power conversion system 400 is coupled to an AC voltage source, where the AC voltage source provides an AC voltage V AC to the DC stage 403. The DC stage 403 includes an output capacitor C across an output load R. The totem pole rectifier stage 402 includes diodes D1 and D2, switches S A1 and S A2 and a boost inductor L2. Each voltage multiplier stage (401a, 401b) includes a first end, a second end, and a third end. The first end of the AC stage is coupled to the first ends of the voltage multiplier stages 401a and 401b through the inductor L1, and the first end of the AC stage is coupled to the third ends of the voltage multiplier stages 401a and 401b through the boost inductor L2. The totem pole rectifier stage 402 includes a first end and a second end coupled together, where the first end of the totem pole rectifier stage 402 is coupled to the second end of the voltage multiplier stage 401a, and the second end of the totem pole rectifier stage 402 is coupled to the second end of the voltage multiplier stage 401b. The DC stage 403 is coupled in parallel to the totem pole rectifier stage 402.

[0110] The voltage multiplier stage 401a includes an energy storage capacitor C1, switches S1, S2, and switch S P1 . The switches S1 and S2 of the voltage multiplier stage 401a are connected in series between the first end and the second end of the voltage multiplier stage 401a, and the switches S1 and S2 of the voltage multiplier stage 401a are connected to a common node. The switch S P1 and the energy storage capacitor C1 of the voltage multiplier stage 401a are connected in series between the common node and the third end of the voltage multiplier stage 401a.

[0111] In the voltage multiplier stage 401a, the series-connected switches S1 and S2 operate at the operating frequency of the power conversion system 400, while the switch S P1 operates at the line frequency of the AC voltage source. Specifically, the switch S P1 is in the on state when the AC voltage V AC is positive, and the switch S P1 is in the off state when the AC voltage V AC is negative. The switch S P1 is connected between the energy storage capacitor C1 and the common terminal of the series-connected switches S1 and S2. The switch S P1 can also be regarded as the line frequency switch S P1 .

[0112] The voltage multiplier stage 401b includes an energy storage capacitor C2 and switches S3, S4, and S N1 . The switches S3 and S4 are connected in series between the first end and the second end of the voltage multiplier stage 401b, and the switches S3 and S4 are connected to a common node. The switch S N1 and the energy storage capacitor C2 are connected in series between the common node and the third end of the voltage multiplier stage 401b. The switch S N1 can also be regarded as the line frequency switch S N1 .

[0113] In this embodiment, the voltage multiplier stage 401b is substantially the same as the voltage multiplier stage 401a. In the voltage multiplier stage 401b, the series-connected switches S3 and S4 operate at the operating frequency, while the switch S N1 operates at the line frequency of the input voltage source. Different from the line frequency switch S P1 , the line frequency switch S N1 is in the off state when the input voltage V AC is positive, and the line frequency switch S N1 is in the on state when the input voltage V AC is negative. The energy storage capacitor C2 is connected between the energy storage capacitor C1 and the common node of the switches S3 and S4. As Figure 4 shown, the voltage multiplier stages 401a and 401b are connected to each other at the connection of the switches S2 and S3 and at the connection of the energy storage capacitors C1 and C2.

[0114] The totem-pole rectifier stage 402 includes first and second half-bridge arms, each half-bridge arm includes a first and a second element connected in series, and the first and second elements are both connected to a common terminal. The second terminal of the AC stage is coupled to the common terminal of the second half-bridge arm, and the common terminal of the first half-bridge arm is coupled to the third terminals of the voltage multiplier stages 401a and 401b. As Figure 4 shown, the first and second elements of the first half-bridge arm of the totem-pole rectifier stage 402 include switches S A1 and S A2 , and the first and second elements of the second half-bridge arm of the totem-pole rectifier stage 402 include diodes D1 and D2.

[0115] In some embodiments, the switch S P1 of the voltage multiplier stage 401a and the switch S N1 of the voltage multiplier stage 401b include semiconductor switching devices.

[0116] The voltage multiplier stages 401a and 401b share an inductor L1, where the inductor L1 is coupled between the AC voltage source and the common terminal of the switches S2 and S3. The common terminal of the energy storage capacitors C1 and C2 is coupled to the common terminal of the switches S A1 and S A2 of the totem-pole rectifier stage 402. Under steady-state conditions, if there is an appropriate volt-second balance between the inductors L1 and L2, the voltages on the energy storage capacitors C1 and C2 are approximately half of the output voltage V O , where the output voltage V O is greater than or equal to the peak value of the input voltage V AC .

[0117] Figure 5 is a schematic circuit diagram of an AC-DC power conversion system 500 according to another embodiment of the present case. The AC-DC power conversion system 500 is substantially similar to the Figure 4 AC-DC power conversion system 400, except that, compared with the diodes D1 and D2 of the totem-pole rectifier stage 402, the totem-pole rectifier stage 502 is changed to include synchronous rectifiers or switches S N2 and S P2 . The switch S P2 is only in the conducting state when the input AC voltage V AC is positive, and the switch S N2 is only in the off state when the input AC voltage V AC is negative. As Figure 5 shown, the voltage multiplier stages 501a and 501b and the DC stage 503 are substantially respectively the same as the Figure 4The voltage multiplier stages 401a and 401b are the same as the DC stage 403. The totem-pole rectifier stage 502 includes first and second half-bridge arms, where the first half-bridge arm is formed by switches S A1 and S A2 connected in series, and the second half-bridge arm is formed by switches S N2 and S P2 connected in series. The second end of the AC stage is coupled to the common end of switches S N2 and S P2 . The common end of switches S A1 and S A2 is coupled to the third end of the voltage multiplier stages 501a and 501b. The switches S A1 , S A2 , S N2 and S P2 can all be implemented by synchronous rectifiers.

[0118] Figure 6 is a timing diagram of the switching actuation control signals of switches S3, S4 and S Figure 5 for controlling the AC-DC power conversion system 500 during a period, where during this period, the input AC voltage V A2 is in the positive half-cycle, and the magnitude of the input AC voltage V AC is less than one-quarter of the output voltage V AC . Additionally, during this period, the line-frequency switches S O and S P1 are in the conducting state. As Figure 6 shows, each switching actuation control signal has a duty cycle D, that is, the conduction duration of each switch is equal to DT S , where T S is the switching period. The switching actuation control signals of switches S3 and S4 are 180 degrees out of phase with the switching actuation control signal of switch S A2 . The actuation parts of the switching actuation control signals of switches S3, S4 and S A2 can partially overlap during the working cycle (i.e., the duty cycle D is greater than 0.5), where during the time period from t0 to t1 and during the time period from t2 to t3, switches S3, S4 and S A2 are simultaneously in the conducting state. Additionally, the switching period T S is much smaller than the period of the line frequency.

[0119] Figure 7 Figure 5 is a topological diagram of the AC-DC power conversion system 500 during the time period from t0 to t1 or during the time period from t2 to t3, that is, showing the current flow direction. During the time period from t0 to t1 or during the time period from t2 to t3, switches S3, S4 and S A2 ​​is in the conducting state. Since the input AC voltage V AC is in the positive half-cycle, the line-frequency switches S P1 and S P2 are also in the conducting state. The input AC voltage V AC is applied to the inductors L1 and L2 through the switches S3, S4 and S A2 . Therefore, if the inductance values of the inductors L1 and L2 are both equal to the inductance value L, the inductor currents i L1 and i L2 on the inductors L1 and L2 both rise linearly with a slope of .

[0120] Figure 8 is Figure 5 a schematic topology diagram of the AC-DC power conversion system 500 during the time period from t1 to t2. As Figure 8 shown, during this period, the switch S A2 is in the conducting state, while the switches S3 and S4 are in the off state. Therefore, the inductor current i L1 on the inductor L1 flows through the body diode of the switch S2 and the switch S P1 , and the energy stored in the inductor L1 during the time period from t0 to t1 or during the time period from t2 to t3 (i.e., when the switches S3 and S4 are in the conducting state) is transferred to the energy storage capacitor C1. Assuming that the line frequency of the input AC voltage V AC varies slowly (during the time period from t1 to t4, the input AC voltage V AC can be substantially regarded as a constant V AC (t)), the voltage on the energy storage capacitor C1 can be derived from the volt-second balance equation (1) of the inductor L1.

[0121] DT S ||V AC (t)|| = [V C1 (t) - ||V AC (t)||][T S - DT S (1)

[0122] From equation (1), the voltage V C1 on the energy storage capacitor C1 can be derived as:

[0123]

[0124] During steady-state operation, if the energy storage capacitor C1 has a relatively large capacitance value, the voltage V C1 is substantially a constant.

[0125] Figure 9 is Figure 5Topological schematic diagram of the AC-DC power conversion system 500 during the time period from t3 to t4. As Figure 9 shown, during this period, switches S3 and S4 are in the on state, while switch S A2 is in the off state. Therefore, the inductor current i L2 on inductor L2 flows through the energy storage capacitor C1, the body diode of switch S P1 and switch S1. The energy stored in inductor L2 during the conduction period of switch S A2 is transferred to the output capacitor C. During the time period from t3 to t4, the energy storage capacitor C1 is connected in series with the output capacitor C, so that the energy stored in the energy storage capacitor C1 during the time period from t1 to t2 can be transferred to the output capacitor C. Accordingly, the AC-DC power conversion system 500 can obtain a high voltage gain. The voltage on the output capacitor C can be derived from the volt-second balance equation (3) of inductor L2.

[0126] DT S ||V AC (t)||=[V O (t)-V C1 (t)-||V AC (t)||][T S -DT S (3)

[0127] The output voltage V O can be derived through equations (2) and (3):

[0128]

[0129] According to equation (4), the voltage conversion ratio of the power conversion system 500 can be derived:

[0130]

[0131] When the power conversion system 500 operates with a duty cycle greater than 0.5, the output voltage V O is twice the output voltage of a traditional boost converter at the same duty cycle. Since a high duty cycle of the switch actuation control signal is not required to generate a high voltage output, this high conversion ratio enables the power conversion system 500 to be applicable to application environments where a high input-output voltage gain is preferred.

[0132] Figure 10 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 under Figure 6 the operating conditions. It should be noted that each switch in the power conversion system 500 performs switching operations when the voltage across it is less than half of the output voltage V O , so the switching losses can be reduced.

[0133] Figure 11 For controlling Figure 5 Switch S3, S4, and S of the AC-DC power conversion system 500 A2 Schematic diagram of the timing of the switch actuation control signals within a period, during which the input AC voltage V AC Is in the positive half-cycle, and the magnitude of the input AC voltage V AC Is greater than one-quarter of the output voltage V O In addition, during this period, the line frequency switches S P1 And S P2 Are in the conducting state. As Figure 11 Shown, each switch actuation control signal has a duty cycle D. The switch actuation control signals of switches S3 and S4 and the switch actuation control signal of switch S A2 Are phase-shifted by 180 degrees. The actuation portions of the switch actuation control signals of switches S3 and S4 during the working cycle and the actuation portion of the switch actuation control signal of switch S A2 During the working cycle do not overlap (i.e., the duty cycle D is less than 0.5), where during the time period from t1 to t2 and the time period from t3 to t4, switches S3, S4, and S A2 Are simultaneously in the off state. In addition, the switching period T S Is much smaller than the period of the line frequency.

[0134] Figure 12 Is Figure 5 Schematic diagram of the topology of the AC-DC power conversion system 500 during the time period from t1 to t2 or during the time period from t3 to t4. During the time period from t1 to t2 or during the time period from t3 to t4, switches S3, S4, and S A2 Are all in the off state. Since the input voltage V AC Is in the positive half-cycle, the line frequency switches S P1 And S P2 Are in the conducting state. The inductor current i L1 On inductor L1 flows through the body diodes of switches S2 and S1, while the inductor current i L2 On inductor L2 flows through switch S P1 And the body diode of switch S1. By turning on switch S P2 , these currents can charge the output capacitor C on the return current path. During the time period from t2 to t3, when switches S3 and S4 are in the off state and switch S A2 Is in the conducting state, the topology of the AC-DC power conversion system 500 is the same as that shown in Figure 8 . During the time period from t0 to t1, when switches S3 and S4 are in the conducting state and switch S A2 Is in the off state, the topology of the AC-DC power conversion system 500 is the same asFigure 9 is the same as shown. The voltage V on the energy storage capacitor C1 C1 can be derived from the volt-second balance equation (6) of the inductor L2.

[0135] DT S ||V AC (t)|| = [V O (t) - V C1 (t) - ||V AC (t)||][T S - DT S (6)

[0136] The voltage V on the energy storage capacitor C1 can be derived through equation (6) C1 :

[0137]

[0138] In addition, the voltage V on the energy storage capacitor C1 C1 can also be derived from the volt-second balance equation (8) of the inductor L1.

[0139]

[0140] The voltage V on the energy storage capacitor C1 can be derived through equation (8) C1 :

[0141]

[0142] According to equations (7) and (9), the output voltage V can be derived O :

[0143]

[0144] After rearranging equation (10), the voltage conversion ratio of the power conversion system 500 can be obtained, where the power conversion system 500 operates at a duty cycle D less than 0.5.

[0145]

[0146] Figure 13 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 under Figure 11 the operating conditions.

[0147] Figure 14 is a timing diagram of the switching actuation control signals of the switches S1, S2, and S of the AC-DC power conversion system 500 for controlling Figure 5 during a period, where during this period, the input voltage V A1 is in the negative half-cycle, and the input AC voltage V AC is in the negative half-cycle, and the input AC voltage VAC is less than a quarter of the output voltage V. Additionally, during this period, the line frequency switches S O and S N1 are in the conducting state. As shown in N2 , the switching actuation control signals of switches S1, S2, and S Figure 14 all have a duty cycle D. The switching actuation control signals of switches S1 and S2 and the switching actuation control signal of switch S A1 are out of phase by 180 degrees. The actuation portions of the switching actuation control signals of switches S1 and S2 during the operating cycle and the actuation portion of the switching actuation control signal of switch S A1 during the operating cycle can partially overlap (i.e., the duty cycle D is greater than 0.5), where during the period from time t0 to t1 and during the period from time t2 to t3, switches S1, S2, and S A1 are simultaneously in the conducting state. Additionally, the switching period T A1 is much smaller than the period of the line frequency. S

[0148] Figure 15 is Figure 5 a schematic topological diagram of the AC-DC power conversion system 500 during the period from time t0 to t1 or during the period from time t2 to t3 under the Figure 14 operating conditions. During the period from time t0 to t1 or during the period from time t2 to t3, switches S1, S2, and S A1 are in the conducting state. Since the input AC voltage V AC is in the positive half-cycle, the line frequency switches S N1 and S N2 are also in the conducting state. The input AC voltage V AC is applied to inductors L1 and L2 through switches S1, S2, and S A1 . Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor currents i L1 and i L2 on inductors L1 and L2 both linearly decrease with a slope of .

[0149] Figure 16 is Figure 5 a schematic topological diagram of the AC-DC power conversion system 500 during the period from time t1 to t2 under the Figure 14 operating conditions. As shown in Figure 16 , during this period, switch S A1 is in the conducting state, while switches S1 and S2 are in the off state. Therefore, the inductor current i L1 on inductor L1 flows through the body diode of switch S3 and switch S N1 ​, the energy stored in inductor L1 during time t0 to t1 or during time t2 to t3 (i.e., when switches S1 and S2 are in the conducting state) is transferred to energy storage capacitor C2. Assuming that the line frequency of input AC voltage V AC changes slowly (i.e., during time t1 to t4, input AC voltage V AC can be regarded as being in a normal state of V AC (t)), the voltage across energy storage capacitor C2 can be derived from the volt-second balance equation of inductor L1. According to the aforementioned equations (1) and (2), During steady-state operation, if energy storage capacitor C1 has a relatively large capacitance value, then voltage V C1 is substantially a constant.

[0150] Figure 17 is Figure 5 a schematic topological diagram of the AC-DC power conversion system 500 at during time t3 to t4 under Figure 14 the operating conditions. As Figure 17 shown, during this period, switches S1 and S2 are in the conducting state, while switch S A1 is in the off state. Therefore, the inductor current i L2 in inductor L2 flows through energy storage capacitor C2, the body diode of switch S N1 and switch S4. The energy stored in inductor L2 during the conduction period of switch S A1 is transferred to output capacitor C. During time t3 to t4, energy storage capacitor C2 is connected in series with output capacitor C, so that the energy stored in energy storage capacitor C2 during time t1 to t2 can be transferred to output capacitor C. Accordingly, the AC-DC power conversion system 500 can obtain a high voltage gain. The voltage across output capacitor C can be derived from the volt-second balance equation of inductor L2. The derivation process is substantially the same as the aforementioned equations (3) to (5), and we can obtain Therefore, the voltage conversion ratio of the AC-DC power conversion system 500 is also

[0151] Figure 18 shows the ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 under Figure 14 the operating conditions.

[0152] Figure 19 is a timing diagram of the switch actuation control signals for switches S1, S2 and S Figure 5 of the AC-DC power conversion system 500 for controlling A1 during a period, in which during this period, the input AC voltage V AC is in the negative half-cycle, and the magnitude of the input AC voltage V AC is greater than the output voltage V OOne quarter. Additionally, during this period, line frequency switches S N1 and S N2 are in the conducting state. As Figure 19 shown, the switching actuation control signals of switches S1, S2, and S A1 all have a duty cycle D. The switching actuation control signals of switches S1 and S2 and the switching actuation control signal of switch S A1 are out of phase by 180 degrees. The actuation portions of the switching actuation control signals of switches S1 and S2 during the operating cycle and the actuation portion of the switching actuation control signal of switch S A1 during the operating cycle do not overlap (i.e., the duty cycle D is less than 0.5). Among them, during the time period from t1 to t2 and the time period from t3 to t4, switches S1, S2, and S A1 are simultaneously in the off state. Additionally, the switching period T S is much smaller than the period of the line frequency.

[0153] Figure 20 is Figure 5 of the AC-DC power conversion system 500 at Figure 19 under the operating conditions during the time period from t1 to t2 or during the time period from t3 to t4. During the time period from t1 to t2 or during the time period from t3 to t4, switches S1, S2, and S A1 are all in the off state. Since the input AC voltage V AC is in the negative half cycle, the line frequency switches S N1 and S N2 are in the conducting state. The inductor current i L1 on inductor L1 flows through the body diodes of switches S3 and S4, and the inductor current i L2 on inductor L2 flows through switch S N1 and the body diode of switch S4. By turning on switch S N2 , these currents can charge the output capacitor C on the return current path. During the time period from t2 to t3, when switches S1 and S2 are in the off state and switch S A1 is in the conducting state, the topology of the AC-DC power conversion system 500 is the same as that shown in Figure 16 . During the time period from t0 to t1, when switches S1 and S2 are in the conducting state and switch S A1 is in the off state, the topology of the AC-DC power conversion system 500 is the same as that shown in Figure 17 . According to the aforementioned equations (6) to (11), through the volt-second balance equations of inductors L1 and L2, the output voltage V O is and the voltage conversion ratio of the AC-DC power conversion system 500 is Among them, the AC-DC power conversion system 500 operates at a duty cycle D less than 0.5.

[0154] Figure 21 The ideal voltage and current waveforms of the components in the AC-DC power conversion system 500 are shown Figure 19 under the operating conditions of

[0155] Figure 5 The AC-DC power conversion system 500 of Figure 22 not only can transfer energy from an AC voltage source to a DC load, but also can transfer energy from a DC voltage source to an AC load. When transferring energy from a DC voltage source to an AC load, the power conversion system operates as a step-down power inverter, which receives a high-voltage DC input voltage and outputs a low-voltage AC output voltage after regulation. AC performs PFC conversion to provide a DC voltage V DC and can further provide an AC-side output voltage V DC based on the DC-side voltage V AC .

[0156] Figure 23 is a timing diagram of the switch actuation control signals for the switches S1 and S2 of the bidirectional AC-DC power conversion system 2200 for controlling Figure 22 during a period. During this period, the output AC voltage V AC is in the positive half-cycle, and the magnitude of the input DC voltage V DC is greater than one-fourth of the output AC voltage V AC . Additionally, during this period, the line frequency switches S P1 and S P2 are in the conducting state. As Figure 23 shown, the switch actuation control signals for the switches S1 and S2 both have a duty cycle D. The switch actuation control signals for the switches S1 and S2 are phase-shifted by 180 degrees from each other. The actuation parts of the switch actuation control signals for the switches S1 and S2 do not overlap during the working cycle (i.e., the duty cycle D is less than 0.5), and during the time period from t1 to t2 and the time period from t3 to t4, the switches S1 and S2 are both in the off state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0157] Figure 24 is Figure 22 a topological diagram of the bidirectional AC-DC power conversion system 2200 during the time period from t0 to t1 under the operating conditions of Figure 23 . During the time period from t0 to t1, as Figure 24As shown, switches S1, S P1 and S P2 are in the conducting state. The input voltage V DC is applied to the output voltage V P1 , inductor L2, and energy storage capacitor C1 through switches S1, S P2 and S AC . Therefore, the inductor current i L2 in inductor L2 rises linearly at a slope of . The output AC voltage V AC is applied to inductor L1 through switch S P2 and the body diodes of switches S3 and S4. Therefore, the inductor current i L1 in inductor L1 decreases linearly at a slope of . If the inductance values of inductors L1 and L2 are both equal to the inductance value L, their corresponding inductor currents change at slopes of and respectively.

[0158] Figure 25 is a topological schematic diagram of the bidirectional AC-DC power conversion system 2200 of Figure 22 under the operating conditions of Figure 23 during the period from time t1 to t2 or during the period from time t3 to t4. As Figure 25 shown, during the period from time t1 to t2 or during the period from time t3 to t4, both switches S1 and S2 are in the off state. The output voltage V AC is applied to inductors L1 and L2 through switch S P2 and the body diodes of switches S3 and S4. Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor currents i L1 and i L2 in inductors L1 and L2 both decrease linearly at a slope of .

[0159] Figure 26 is a topological schematic diagram of the bidirectional AC-DC power conversion system 2200 of Figure 22 under the operating conditions of Figure 23 during the period from time t2 to t3. During this period, as Figure 26 shown, switch S2 is in the conducting state. The output voltage V AC is applied to the energy storage capacitor C1 and inductor L1 through switch S2, S P1 and S P2 and the body diode of switch S A2 . Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor current i L1 in inductor L1 rises linearly at a slope of . The output voltage VAC is also applied to the inductor L2 through the switch S P2 and the body diode of the switch S A2 . If the inductance values of the inductors L1 and L2 are both equal to the inductance value L, then the inductor current i L2 on the inductor L2 decreases linearly with a slope

[0160] If the output voltage V AC has a line frequency alternating current voltage that is substantially constant within the switching period T S , then the voltage on the energy storage capacitor C1 can be derived from the volt-second balance equations (12) and (13) of the inductors L1 and L2.

[0161] [T S -DT S ||V AC (t)||=[||V AC (t)||-V C1 (t)][DT S (12)

[0162] [T S -DT S ||V AC (t)||=[V DC (t)-V C1 (t)-||V AC (t)||][DT S (13)

[0163] From equations (12) and (13), the output voltage V AC can be derived as:

[0164]

[0165] Accordingly, the voltage transformation ratio of the bidirectional AC-DC power conversion system 2200 Figure 22 when transferring energy from the DC voltage V DC to the output voltage V AC can be derived, where the bidirectional AC-DC power conversion system 2200 operates with a duty cycle less than 0.5.

[0166]

[0167] Figure 27 is a timing diagram of the switch actuation control signals of the switches S1 and S2 of the bidirectional AC-DC power conversion system 2200 for controlling Figure 22 during a period, where during this period, the output AC voltage V AC is in the positive half-cycle, and the output AC voltage V ACis sized between a quarter and a half of the input voltage V DC and the energy is transferred from the input voltage source V DC to the output voltage V AC . Additionally, within the switching period Ts, the line-frequency switches S P1 and S P2 are in the conducting state. The switching actuation control signals of switches S1 and S2 are phase-shifted by 180 degrees from each other. The actuation portions of the switching actuation control signals of switches S1 and S2 in the operating cycle can be partially overlapped (i.e., the duty cycle D is greater than 0.5), where switches S1 and S2 are simultaneously in the conducting state during the time period from t0 to t1 and during the time period from t2 to t3. Furthermore, the switching period T S is much smaller than the period of the line frequency.

[0168] Figure 28 is Figure 22 a schematic topology diagram of the bidirectional AC-DC power conversion system 2200 at the operating conditions of Figure 27 during the time period from t0 to t1 or during the time period from t2 to t3. During the time period from t0 to t1 or during the time period from t2 to t3, switches S1, S2, S P1 and S P2 are all in the conducting state. The input voltage V DC is applied to the output voltage V P2 and the inductor L1 through switches S1, S2 and S AC . Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor current i L1 of inductor L1 linearly rises at a slope of

[0169] The schematic topologies of the bidirectional AC-DC power conversion system 2200 at the operating conditions of Figure 27 during the time period from t1 to t2 and during the time period from t3 to t4 have been substantially shown in Figure 26 and Figure 24 respectively. Therefore, the volt-second balance equation of inductor L1 is:

[0170]

[0171] The voltage V C1 on the energy storage capacitor C1 can be derived through Equation (16):

[0172]

[0173] Additionally, the voltage V C1 on the energy storage capacitor C1 can also be derived through the volt-second balance equation (18) of inductor L2.

[0174] ||V AC ​(t)||[TS-DT S =[V DC -V C1 (t)-||V AC (t)||][DT S (18)

[0175] The voltage V across the energy storage capacitor C1 can be derived from Equation (18). C1 :

[0176]

[0177] According to Equations (17) and (19), the AC output voltage V can be derived as follows: AC :

[0178] ||V AC (t)||=D 2 V DC (20)

[0179] Accordingly, the voltage conversion ratio of the bidirectional AC-DC power conversion system 2200 can be obtained, where the bidirectional AC-DC power conversion system 2200 operates with a duty cycle D greater than 0.5.

[0180]

[0181] Through Equations (19) and (20), the voltage V across the energy storage capacitor C1 can be derived as follows: C1 :

[0182] V C1 (t)=(1-D)V DC (22)

[0183] Figure 29 For the timing diagram of the switching actuation control signals of switches S3 and S4 of the bidirectional AC-DC power conversion system 2200 for controlling Figure 22 wherein during this period, the output voltage V AC is in the negative half cycle, and the magnitude of the output AC voltage V AC is less than one-fourth of the input DC voltage V DC . Additionally, during this period, the line frequency switches S N1 and S N2 are in the conducting state. As shown in Figure 29As shown, the switch actuation control signals of switches S3 and S4 both have a duty cycle D. The switch actuation control signals of switches S3 and S4 are out of phase by 180 degrees with each other. The actuation parts of the switch actuation control signals of switches S3 and S4 do not overlap during the working cycle (i.e., the duty cycle D is less than 0.5), where during the time period from t1 to t2 and during the time period from t3 to t4, switches S3 and S4 are both in the off state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0184] Figure 30 is Figure 22 a schematic topology diagram of the bidirectional AC-DC power conversion system 2200 at Figure 29 during the time period from t0 to t1 under the operating conditions of Figure 30 As shown, during the time period from t0 to t1, switches S4, S N1 and S N2 are in the on state. The input voltage V DC is applied to the output voltage V N1 and S N2 through switches S4, S AC , inductor L2, and energy storage capacitor C2. Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor current i L2 on inductor L2 rises linearly with a slope of . The output AC voltage V AC is applied to inductor L1 through switch S N2 and the body diodes of switches S1 and S2. Therefore, the inductor current i L1 on inductor L1 decreases linearly with a slope of .

[0185] Figure 31 is Figure 22 a schematic topology diagram of the bidirectional AC-DC power conversion system 2200 at Figure 29 during the time period from t1 to t2 or during the time period from t3 to t4 under the operating conditions of Figure 31 As shown, during the time period from t1 to t2 or during the time period from t3 to t4, switches S1 and S2 are both in the off state. The output voltage V AC is applied to inductors L1 and L2 through switch S N2 and the body diodes of switches S1, S2, and S A1 . Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor currents i L1 and i L2 on inductors L1 and L2 both decrease linearly with a slope of .

[0186] Figure 32 isFigure 22 The topology schematic diagram of the bidirectional AC-DC power conversion system 2200 during the period from time t2 to t3 under Figure 29 the operating conditions. During this period, as Figure 32 shown, the switch S3 is in the on state. The output voltage V AC is applied to the energy storage capacitor C1 and the inductor L1 through the switch S3, S N1 and S N2 and the body diode of the switch S A1 . Therefore, if the inductance values of the inductors L1 and L2 are both equal to the inductance value L, the inductor current i L1 on the inductor L1 rises linearly at a slope of . The output voltage V AC is also applied to the inductor L2 through the switch S N2 and the body diode of the switch S A1 . If the inductance values of the inductors L1 and L2 are both equal to the inductance value L, the inductor current i L2 on the inductor L2 drops linearly at a slope of .

[0187] Figure 33 is the timing schematic diagram of the switch actuation control signals for the switches S3 and S4 that control Figure 22 the bidirectional AC-DC power conversion system 2200 during a period, in which during this period, the output AC voltage V AC is in the negative half cycle, the magnitude of the output AC voltage V AC is between one-quarter and one-half of the input voltage V DC , and the energy is transmitted from the input voltage source V DC to the output voltage V AC . In addition, within the switch period T S , the switches S N1 and S N2 are in the on state. The switch actuation control signals of the switches S3 and S4 are phase-shifted 180 degrees from each other. The actuation parts of the switch actuation control signals of the switches S3 and S4 in the working cycle can partially overlap (i.e., the duty cycle D is greater than 0.5), in which during the period from time t0 to t1 and during the period from time t2 to t3, the switches S3 and S4 are simultaneously in the on state. In addition, the switch period T S is much smaller than the period of the line frequency.

[0188] Figure 34 is the topology schematic diagram of Figure 22 the bidirectional AC-DC power conversion system 2200 during the period from time t0 to t1 or during the period from time t2 to t3 under Figure 33 the operating conditions. During the period from time t0 to t1 or during the period from time t2 to t3, the switches S3, S4, SN1 and S N2 are both in the on state. The input voltage V DC is applied to the output voltage V N2 through switches S3, S4 and S AC and inductor L1. Therefore, if the inductance values of inductors L1 and L2 are both equal to the inductance value L, the inductor current i L1 of inductor L1 rises linearly at a slope .

[0189] The topologies of the bidirectional AC-DC power conversion system 2200 during the time period from t1 to t2 and during the time period from t3 to t4 under the Figure 33 operating conditions have been substantially shown in Figure 30 and Figure 32 respectively.

[0190] Figure 35 FIG. is a schematic circuit diagram of a bidirectional AC-DC power conversion system 3500 according to another embodiment of the present case, wherein the bidirectional AC-DC power conversion system 3500 includes pre-charge resistors R PRE and voltage balancing resistors R BAL in both its voltage multiplier stages 3501a and 3501b. In Figure 35 , the voltage balancing resistors R BAL of the voltage multiplier stages 3501a and 3501b are respectively connected in parallel to the energy storage capacitors C1 and C2. Before each switching cycle (i.e., before switches S1, S2, S3 and S4 are actuated by their switching actuation control signals), the voltages on the energy storage capacitors C1 and C2 are slowly charged by the current flowing through the corresponding pre-charge resistors R PRE , where the pre-charge resistors R PRE are both coupled to the input voltage V DC . In addition, the voltages on the energy storage capacitors C1 and C2 are equalized by the voltage balancing resistors R BAL connected in parallel therewith. Therefore, before the bidirectional AC-DC power conversion system 3500 starts to operate in a switching cycle, the voltages on the energy storage capacitors C1 and C2 are both approximately half of the input voltage V DC .

[0191] Figure 36 FIG. is a schematic circuit diagram of a bidirectional AC-DC power conversion system 3600 according to another embodiment of the present case, wherein the bidirectional AC-DC power conversion system 3600 includes two symmetrical bridge arms, one of which is formed by voltage multiplier stages 3601a and 3601b, and the other is formed by voltage multiplier stages 3601c and 3601d. The bidirectional AC-DC power conversion system 3600 is coupled to an AC voltage source V AC and a DC voltage source V DCand includes voltage multiplier stages 3601a, 3601b, 3601c and 3601d, inductors L1 and L2, and switches (or synchronous rectifiers) S N3 and S P3 . The voltage multiplier stage 3601a includes switches S1, S2 and S P1 , where switches S1 and S2 are connected in series with each other and operate at the frequency of the switching period of the bidirectional AC-DC power conversion system 3600 (i.e., the operating frequency), while switch S P1 operates at the line frequency of the AC voltage source V AC . The operating frequency is substantially greater than the line frequency. Switch S P1 is in the on state during the positive half-cycle of the AC voltage V AC and is in the off state during the negative half-cycle of the AC voltage V AC . The voltage multiplier stage 3601a further includes an energy storage capacitor C1, where the energy storage capacitor C1 is connected to the common terminal of switches S1 and S2 via switch S P1 . The common terminal of switches S N3 and S P3 is coupled to the negative terminal of the AC voltage source V AC .

[0192] The voltage multiplier stage 3601b includes switches S3, S4 and S N1 , where switches S3 and S4 are connected in series with each other and operate at the operating frequency, while switch S N1 operates at the line frequency of the AC voltage source V AC . Switch S N1 is in the on state during the negative half-cycle of the AC voltage V AC and is in the off state during the positive half-cycle of the AC voltage V AC . The voltage multiplier stage 3601b further includes an energy storage capacitor C2, where the energy storage capacitor C2 is connected to the common terminal of switches S3 and S4 via switch S N1 .

[0193] The voltage multiplier stage 3601c includes switches S5, S6 and S P2 , where switches S5 and S6 are connected in series with each other and operate at the operating frequency, while switch S P2 operates at the line frequency of the AC voltage source V AC . Switch S P2 is in the on state during the positive half-cycle of the AC voltage V AC and is in the off state during the negative half-cycle of the AC voltage V AC . The voltage multiplier stage 3601c further includes an energy storage capacitor C3, where the energy storage capacitor C3 is connected to the common terminal of switches S5 and S6 via switch S P2 .

[0194] The voltage multiplier stage 3601d includes switches S7, S8, and S N2 , where switches S7 and S8 are connected in series with each other and operate at the operating frequency, while switch S N2 operates at the line frequency of the AC voltage source V AC . Switch S N2 is turned on during the negative half-cycle of the AC voltage V AC and is turned off during the positive half-cycle of the AC voltage V AC . The voltage multiplier stage 3601d also includes an energy storage capacitor C4, where the energy storage capacitor C4 is connected to the common terminal of switches S7 and S8 via switch S N2 .

[0195] As Figure 36 shown, the switch S2 of the voltage multiplier stage 3601a and the switch S3 of the voltage multiplier stage 3601b are connected to a common terminal, and this common terminal is also the common terminal to which the energy storage capacitors C3 and C4 of the voltage multiplier stages 3601c and 3601d are connected. Similarly, the switch S6 of the voltage multiplier stage 3601c and the switch S7 of the voltage multiplier stage 3601d are connected to a common terminal, and this common terminal is also the common terminal to which the energy storage capacitors C1 and C2 of the voltage multiplier stages 3601a and 3601b are connected. The AC voltage V AC is coupled to the common terminal of the switches S2 and S3 of the voltage multiplier stages 3601a and 3601b through the inductor L1, where this common terminal is also the common terminal to which the energy storage capacitors C3 and C4 of the voltage multiplier stages 3601c and 3601d are connected. Similarly, the AC voltage V AC is coupled to the common terminal of the switches S6 and S7 of the voltage multiplier stages 3601c and 3601d through the inductor L2, where this common terminal is also the common terminal to which the energy storage capacitors C1 and C2 of the voltage multiplier stages 3601a and 3601b are connected.

[0196] Figures 37 to 44 Shows Figure 36 the AC-DC conversion operation process of the bidirectional AC-DC power conversion system 3600.

[0197] Figure 37 Is a timing diagram of the switch actuation control signals of the switches S3, S4, S7, and S8 of the bidirectional AC-DC power conversion system 3600 for controlling Figure 36 during a period, where during this period, the input AC voltage V AC is in the positive half-cycle, the magnitude of the input AC voltage V AC is less than one-fourth of the output voltage V DC , and energy is transmitted from the input AC voltage source V AC to the output voltage V DC . Under these operating conditions, switch SP1 , S P2 and S P3 are in the conducting state, and switches S1, S2, S5, S6, S N1 , S N2 and S N3 are in the off state.

[0198] As Figure 37 shown, switches S3 and S4 switch synchronously and have the same switching waveform, and switches S7 and S8 switch synchronously and have the same switching waveform. Each switch actuation control signal has a duty cycle D. The switch actuation control signals of switches S4 and S8 are phase-shifted by 180 degrees from each other. The actuation portions of the switch actuation control signals of switches S3 and S4 during the operating cycle may partially overlap with the actuation portions of the switch actuation control signals of switches S7 and S8 during the operating cycle (i.e., the duty cycle D is greater than 0.5), where during the time period from t0 to t1 and the time period from t2 to t3, switches S3, S4, S7, and S8 are simultaneously in the conducting state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0199] Figure 38 shows Figure 36 the ideal voltage and current waveforms of the components in the Figure 37 AC-DC power conversion system 3600 under the

[0200] Figure 39 operating conditions. Figure 36 is a timing diagram of the switch actuation control signals of switches S3, S4, S7, and S8 for controlling the AC bidirectional AC-DC power conversion system 3600 during a period, where during this period, the input voltage V AC is in the positive half-cycle, the magnitude of the input AC voltage V DC is greater than one-fourth of the output DC voltage V AC , and energy is transmitted from the input AC voltage source V DC to the output DC voltage V P1 , S P2 and S P3 are in the conducting state, and switches S1, S2, S5, S6, S N1 , S N2 and S N3 are in the off state.

[0201] As Figure 39As shown, switches S3 and S4 are switched synchronously and have the same switching waveform, and switches S7 and S8 are switched synchronously and have the same switching waveform. Each switch actuation control signal has a duty cycle D. The switch actuation control signals of switches S3 and S7 are phase-shifted by 180 degrees from each other. The actuation portions of the switch actuation control signals of switches S3 and S7 in the operating cycle do not overlap (i.e., the duty cycle D is less than 0.5), where during the time period from t1 to t2 and the time period from t3 to t4, switches S3 and S7 are simultaneously in the off state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0202] Figure 40 shows Figure 36 the ideal voltage and current waveforms of the components in the Figure 39 AC-DC power conversion system 3600 under

[0203] Figure 41 is a timing diagram of the switch actuation control signals for controlling Figure 36 the bidirectional AC-DC power conversion system 3600 of switches S1, S2, S5, and S6 during a period, where during this period, the input AC voltage V AC is in the negative half-cycle, the magnitude of the input AC voltage V AC is less than one-fourth of the output voltage V DC , and energy is transferred from the input AC voltage source V AC to the output DC voltage V DC . Under these operating conditions, switches S N1 , S N2 and S N3 are in the on state, and switches S3, S4, S7, S8, S P1 , S P2 and S P3 are in the off state.

[0204] As Figure 41 shown, switches S1 and S2 are switched synchronously and have the same switching waveform, and switches S5 and S6 are switched synchronously and have the same switching waveform. Each switch actuation control signal has a duty cycle D. The switch actuation control signals of switches S1 and S5 are phase-shifted by 180 degrees from each other. The actuation portions of the switch actuation control signals of switches S1 and S2 in the operating cycle may partially overlap with the actuation portions of the switch actuation control signals of switches S5 and S6 in the operating cycle (i.e., the duty cycle D is greater than 0.5), where during the time period from t0 to t1 and the time period from t2 to t3, switches S1, S2, S5, and S6 are simultaneously in the on state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0205] Figure 42 shows Figure 36 the ideal voltage and current waveforms of the components in the AC-DC power conversion system 3600 of Figure 41 under the operating conditions of

[0206] Figure 43 For controlling Figure 36 the timing diagram of the switch actuation control signals of the bidirectional AC-DC power conversion system 3600 for switches S1, S2, S5, and S6 during a period, where during this period, the input voltage V AC is in the negative half-cycle, the magnitude of the input AC voltage V AC is greater than one-fourth of the output DC voltage V DC , and energy is transmitted from the input AC voltage source V AC to the output DC voltage V DC . Additionally, during this period, the line frequency switches S N1 , S N2 , and S N3 are in the on state, and the switches S3, S4, S7, S8, S P1 , S P2 , and S P3 are in the off state.

[0207] As Figure 43 shown, switches S1 and S2 switch synchronously and have the same switching waveform, and switches S5 and S6 switch synchronously and have the same switching waveform. Each switch actuation control signal has a duty cycle D. The switch actuation control signals of switches S1 and S5 are phase-shifted by 180 degrees from each other. The actuation parts of the switch actuation control signals of switches S1 and S5 do not overlap during the operating cycle (i.e., the duty cycle D is less than 0.5), where during the time period from t1 to t2 and the time period from t3 to t4, switches S1 and S5 are both in the off state. Additionally, the switching period T S is much smaller than the period of the line frequency.

[0208] Figure 44 shows Figure 36 the ideal voltage and current waveforms of the components in the AC-DC power conversion system 3600 of Figure 43 under the operating conditions of

[0209] Figures 45 to 48 Shows Figure 36 the DC-AC conversion operation process of the bidirectional AC-DC power conversion system 3600. In the DC-AC conversion, switches S1 and S5 cannot be in the on state simultaneously, and switches S4 and S8 cannot be in the on state simultaneously.

[0210] Figure 45 For controlling Figure 36Timing diagram of the switch actuation control signals of switches S1, S2, S5, and S6 of the bidirectional AC-DC power conversion system 3600 during a period, where during this period, the output voltage V AC is in the positive half-cycle, and the magnitude of the output AC voltage V AC is greater than one-fourth of the input DC voltage V DC , and the energy is transferred from the input DC voltage source V DC to the output AC voltage V AC . Additionally, during this period, the line frequency switches S P1 , S P2 , and S P3 are in the on state, and the switches S3, S4, S7, S8, S N1 , S N2 , and S N3 are in the off state. As shown in Figure 45 , switches S1 and S6 switch synchronously and have the same switching waveform, and switches S2 and S5 switch synchronously and have the same switching waveform. Each switch actuation control signal has a duty cycle D. The switch actuation control signals of switches S1 and S2 are phase-shifted by 180 degrees from each other. The actuation portions of the switch actuation control signals of switches S1 and S2 during the operating cycle do not overlap (i.e., the duty cycle D is less than 0.5), where during the time period from t1 to t2 and the time period from t3 to t4, switches S1, S2, S5, and S6 are all in the off state. Additionally, the switching period T S is much smaller than the period of the line frequency.

[0211] Under the operating conditions shown in Figure 45 , during the time period from t0 to t1 and the time period from t2 to t3, the topology of the AC-DC power conversion system 3600 is substantially equivalent to the combination of the topologies shown in Figure 24 and 26 . During the time period from t1 to t2 and the time period from t3 to t4, the topology of the AC-DC power conversion system 3600 is substantially equivalent to the topology shown in Figure 25 .

[0212] Figure 46 is a timing diagram of the switch actuation control signals of switches S1 and S2 of the bidirectional AC-DC power conversion system 3600 for controlling Figure 36 during a period, where during this period, the output AC voltage V AC is in the positive half-cycle, and the magnitude of the output AC voltage V AC is greater than one-fourth of the input voltage V DC , and the energy is transferred from the input DC voltage source V DC to the output AC voltage V AC . Under these operating conditions, the switch SP1 and S P3 are in the on state, and switches S3, S4, S5, S6, S7, S8, S P2 , S N1 , S N2 and S N3 are in the off state. As Figure 46 shown, the switching actuation control signals of switches S1 and S2 both have a duty cycle D. The switching actuation control signals of switches S1 and S2 are out of phase by 180 degrees with each other. The actuation parts of the switching actuation control signals of switches S1 and S2 during the operating cycle can partially overlap with each other (i.e., the duty cycle D is greater than 0.5), where during the time period from t0 to t1 and the time period from t2 to t3, switches S1 and S2 are simultaneously in the on state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0213] During Figure 46 the operating conditions shown, during the time period from t0 to t1 and the time period from t2 to t3, the topology of the AC-DC power conversion system 3600 is substantially equivalent to Figure 28 the topology shown. During the time period from t1 to t2 and the time period from t3 to t4, the topology of the AC-DC power conversion system 3600 is substantially equivalent to Figure 25 and Figure 24 the topologies shown, respectively.

[0214] Figure 47 is a timing diagram of the switching actuation control signals of switches S3, S4, S7, and S8 of the bidirectional AC-DC power conversion system 3600 for controlling Figure 36 during a period, where during this period, the output voltage V AC is in the negative half cycle, the magnitude of the output AC voltage V AC is less than one-fourth of the input DC voltage V DC , and the energy is transmitted from the input DC voltage source V DC to the output AC voltage V AC . In addition, during this period, the line frequency switches S N1 , S N2 and S N3 are in the on state, and switches S1, S2, S5, S6, S P1 , S P2 and S P3 are in the off state. As Figure 47As shown, switch S3 and S8 switch synchronously and have the same switching waveform, and switch S4 and S7 switch synchronously and have the same switching waveform. Each switch actuation control signal has a duty cycle D. The switch actuation control signals of switch S3 and S4 are phase-shifted by 180 degrees from each other. The actuation portions of the switch actuation control signals of switch S3 and S4 do not overlap during the working cycle (i.e., the duty cycle D is less than 0.5), where during the time period from t1 to t2 and the time period from t3 to t4, switches S3, S4, S7, and S8 are all in the off state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0215] During Figure 47 the operating conditions shown, during the time period from t0 to t1 and the time period from t2 to t3, the topology of the AC-DC power conversion system 3600 is substantially equivalent to Figure 30 and Figure 32 the combination of the topologies shown. During the time period from t1 to t2 and the time period from t3 to t4, the topology of the AC-DC power conversion system 3600 is substantially equivalent to Figure 31 the topology shown.

[0216] Figure 48 is a timing diagram of the switch actuation control signals of switches S3 and S4 for controlling Figure 36 the bidirectional AC-DC power conversion system 3600 within a period, where during this period, the output AC voltage V AC is in the negative half cycle, the magnitude of the output AC voltage V AC is greater than one-fourth of the input voltage V DC , and energy is transmitted from the input DC voltage source V DC to the output AC voltage V AC . Under these operating conditions, switches S N1 and S N3 are in the on state, and switches S1, S2, S5, S6, S7, S8, S N2 , S P1 , S P2 and S P3 are in the off state. As [[ID shown, the switch actuation control signals of switches S3 and S4 both have a duty cycle D. The switch actuation control signals of switches S3 and S4 are phase-shifted by 180 degrees from each other. The actuation portions of the switch actuation control signals of switches S3 and S4 can partially overlap during the working cycle (i.e., the duty cycle D is greater than 0.5), where during the time period from t0 to t1 and the time period from t2 to t3, switches S3 and S4 are simultaneously in the on state. In addition, the switching period T S is much smaller than the period of the line frequency.

[0217] During​ Under the operating conditions shown, during the time period from t0 to t1 and from t2 to t3, the topology of the AC-DC power conversion system 3600 is substantially equivalent to ​ the topology shown. During the time period from t1 to t2 and from t3 to t4, the topology of the AC-DC power conversion system 3600 is substantially equivalent to ​ and ​ the topology shown respectively.

[0218] ​ FIG. is a schematic circuit diagram of a bidirectional AC-DC power conversion system 4900 according to another embodiment of the present case. The bidirectional AC-DC power conversion system 4900 includes three symmetric bridge arms formed by voltage multiplier stages 4901a to 4901f. As ​ shown, compared with ​ the AC-DC power conversion system 3600, the AC-DC power conversion system 4900 further includes an additional symmetric bridge arm and an inductor L3, where the additional symmetric bridge arm is formed by voltage multiplier stages 4901e and 4901f. During AC-DC conversion, similar to the operating mode shown in ​ , the three symmetric bridge arms operate based on the magnitudes of the input voltage V AC and the output voltage V DC , and their duty cycles are not restricted. For example, the additional symmetric bridge arm (i.e., the symmetric bridge arm formed by voltage multiplier stages 4901e and 4901f) can operate synchronously with any one of the symmetric bridge arms in the relative symmetric bridge arm. During DC-AC conversion, no two of the switches S1, S5, and S9 can be simultaneously in the conducting state, and no two of the switches S4, S8, and S 12 can be simultaneously in the conducting state. Therefore, during DC-AC conversion, only one symmetric bridge arm (for example, the bridge arm including switches S1, S2, S3, and S4) can operate with a duty cycle greater than 0.5, which is substantially similar to ​ and ​ the bidirectional AC-DC power conversion system 3600 shown. The number of symmetric bridge arms of the bidirectional AC-DC power conversion system of the present case can be arbitrarily extended as needed to facilitate applications requiring high-power transmission. For example, ​ FIG. is a schematic circuit diagram of an AC-DC power conversion system 5000 according to another embodiment of the present case. The AC-DC power conversion system 5000 includes M symmetric bridge arms. The increase in the number of symmetric bridge arms can reduce the current stress on each voltage multiplier stage. In addition, multiple bidirectional AC-DC power conversion systems can be connected in parallel to be applicable to high-current application environments.

[0219] ​Schematic diagram of the circuit structure of the bidirectional AC-DC power conversion system 5100 according to another embodiment of this case. As ​ shown, the bidirectional AC-DC power conversion system 5100 is obtained by adding a relay switch 5101, an inductor L3, and output capacitors C ​ and C O1 and C O2 to the bidirectional AC-DC power conversion system 2200. The relay switch 5101 enables the bidirectional AC-DC power conversion system 5100 to switchably receive a single-phase AC power supply or a three-phase AC power supply. The bidirectional AC-DC power conversion system 5100 can be, for example but not limited to, a battery charger for an electric vehicle, where the electric vehicle can receive a 400V single-phase AC output and an 800V three-phase AC output. ​ and ​ respectively show the circuit structures of the bidirectional AC-DC power conversion system 5100 when its relay switch 5101 is in two positions. It should be noted that when the bidirectional AC-DC power conversion system 5100 receives a three-phase AC input, the connection between the energy storage capacitors C1 and C2 and the relay is interrupted.

[0220] ​ shows the circuit architecture of the bidirectional AC-DC power conversion system 5100, where the relay switch 5101 is in the "up" position, enabling the bidirectional AC-DC power conversion system 5100 to receive a single-phase AC voltage V coupled between ports A and N AC . In this circuit architecture, the relay switch 5101 causes the inductor L3 to operate, so the bidirectional AC-DC power conversion system 5100 operates substantially in the same manner as the ​ bidirectional AC-DC power conversion system 2200 in ​ .

[0221] ​ shows the circuit architecture of the bidirectional AC-DC power conversion system 5100, where the relay switch 5101 is in the "down" position, enabling the bidirectional AC-DC power conversion system 5100 to receive a three-phase AC voltage V AC , where the three phases of the three-phase AC voltage V AC are respectively coupled between ports A and N, between ports B and N, and between ports C and N. In this circuit architecture, switches S1 and S4 are in the conducting state, causing switches S N1 and S P1 and the energy storage capacitors C1 and C2 not to operate. The bidirectional AC-DC power conversion system 5100 operates substantially like a conventional six-switch three-phase PFC circuit.

[0222] ​Schematic diagram of the circuit structure of the bidirectional AC-DC power conversion system 5400 according to another embodiment of this case. The bidirectional AC-DC power conversion system 5400 is to ​ The switches S in the voltage multiplier stages 501a and 501b of the bidirectional AC-DC power conversion system 5100 P1 and S N1 are replaced with bidirectional switches. As ​ shown, the voltage multiplier stage 5401a includes a bidirectional switch formed by the switching devices S P1 and S P3 . Similarly, the voltage multiplier stage 5401b includes a bidirectional switch formed by the switching devices S N1 and S N3 . In any bidirectional switch, since the body diode directions of its two switching devices are opposite, when the bidirectional switch is in the off state, there is actually no current flowing in either direction. In ​ , the bidirectional switch of the voltage multiplier stage 5401a is formed by the power semiconductor switching devices S P1 and S P3 connected in series, and their body diodes are connected in opposite polarities. Similarly, the bidirectional switch of the voltage multiplier stage 5401b is formed by the power semiconductor switching devices S N1 and S N3 connected in series, and their body diodes are connected in opposite polarities.

[0223] ​ shows the circuit architecture of the bidirectional AC-DC power conversion system 5400, where the relay switch 5101 is in the "up" position, enabling the bidirectional AC-DC power conversion system 5400 to receive a single-phase AC voltage V AC coupled between ports A and N. During AC-DC conversion, the switches S P3 and S P1 act synchronously, and the switches S N3 and S N1 also act synchronously. Under this circuit architecture, the relay switch 5101 stops the inductor L3 from operating.

[0224] ​ shows the circuit architecture of the bidirectional AC-DC power conversion system 5400, where the relay switch 5101 is in the "down" position, enabling the bidirectional AC-DC power conversion system 5400 to receive a three-phase AC voltage V AC , where the three phases of the three-phase AC voltage V AC are respectively coupled between ports A and N, between ports B and N, and between ports C and N. In this circuit architecture, the switches S1 and S4 are in the conducting state, so that the bidirectional switch (i.e., the switches S N1 , S N3 , SP1 and S P3 ) and the energy storage capacitors C1 and C2 stop operating, and the bidirectional AC-DC power conversion system 5400 operates substantially as a known six-switch three-phase PFC circuit. Since the body diodes in each bidirectional switch face in opposite directions, no current can flow through the energy storage capacitors C1 and C2 when the bidirectional switch is in the off state. Some applications prefer this level of isolation.

[0225] It should be noted that the above are only examples proposed for the purpose of illustrating the present case. The present case is not limited to the above examples, and the scope of the present case is determined by the appended claims. And the present case can be variously modified by those skilled in the art, but all are not beyond what is intended to be protected by the appended claims.

Claims

1. An AC-DC power conversion system, comprising: An AC stage, including a first end and a second end; A first inductor; A first voltage multiplier stage and a second voltage multiplier stage, wherein each of the voltage multiplier stages includes a first end, a second end and a third end, and the first end of the AC stage is coupled to the first end of each of the voltage multiplier stages via the first inductor; A totem-pole rectifier stage includes a second inductor and has first and second terminals coupled in phase, wherein, The first end of the totem-pole rectifier stage is coupled to the second end of the first voltage multiplier stage, the second end of the totem-pole rectifier stage is coupled to the second end of the second voltage multiplier stage, and the first end of the AC stage is coupled to the third end of each of the voltage multiplier stages via the second inductor; And A DC stage, coupled in parallel to the totem-pole rectifier stage, Wherein each of the voltage multiplier stages includes a capacitor and first, second and third switches. The first and second switches of the voltage multiplier stage are connected in series between the first and second ends of the voltage multiplier stage. The first and second switches of the voltage multiplier stage are connected to a common terminal. The third switch and the capacitor of the voltage multiplier stage are connected in series between the common terminal and the third end of the voltage multiplier stage.

2. The AC-DC power conversion system according to claim 1, wherein The totem-pole rectifier stage includes a first half-bridge arm and a second half-bridge arm. Each of the half-bridge arms includes a first and a second element connected in series to a common terminal. The second end of the AC stage is coupled to the common terminal of the second half-bridge arm. The common terminal of the first half-bridge arm is coupled to the third end of each of the voltage multiplier stages.

3. The AC-DC power conversion system according to claim 2, wherein The first and second elements of the first half-bridge arm and the second half-bridge arm of the totem-pole rectifier stage include synchronous rectifiers.

4. The AC-DC power conversion system according to claim 2, wherein The first and second elements of one of the half-bridge arms of the totem-pole rectifier stage include diodes.

5. The AC-DC power conversion system according to claim 1, wherein, The third switch operates at a signal frequency of the AC stage.

6. The AC-DC power conversion system according to claim 1, wherein, Each of the voltage multiplier stages further includes a balancing resistor, and the balancing resistor is connected in parallel to the capacitor of the voltage multiplier stage.

7. The AC-DC power conversion system according to claim 1, wherein, Each of the voltage multiplier stages further includes a pre-charge resistor, and the pre-charge resistor is connected between the second end of the voltage multiplier stage and one end of the capacitor.

8. The AC-DC power conversion system according to claim 1, wherein, The third switch of each of the voltage multiplier stages includes a bidirectional switch.

9. The AC-DC power conversion system according to claim 8, wherein, The bidirectional switch includes two power semiconductor switch devices connected together, and the body diodes of the two power semiconductor switch devices are connected with opposite polarities.

10. The AC-DC power conversion system according to claim 1, wherein, In AC-DC conversion, the AC-DC power conversion system obtains a gain, and the gain depends on operating the first and second switches of each of the voltage multiplier stages at a preset duty cycle.

11. The AC-DC power conversion system according to claim 10, wherein, The preset duty cycle corresponding to each of the voltage multiplier stages is greater than 0.

5.

12. The AC-DC power conversion system according to claim 1, wherein, In DC-AC conversion, at least one of the first and second switches of each of the voltage multiplier stages is in an off state at any time.

13. The AC-DC power conversion system according to claim 1, wherein, The first and second voltage multiplier stages form a first symmetric bridge arm, and the AC-DC power conversion system further includes a second symmetric bridge arm connected between the AC stage and the totem-pole rectifier stage.

14. The AC-DC power conversion system according to claim 13, wherein, The totem-pole rectifier stage includes a half-bridge arm, and the half-bridge arm includes a first and a second element connected in series to a common terminal. The second end of the AC stage is coupled to the common terminal of the half-bridge arm.

15. The AC-DC power conversion system according to claim 14, wherein, The second symmetric bridge arm includes first and second voltage multiplier stages, and the first and second voltage multiplier stages of the second symmetric bridge arm are substantially the same as the first and second voltage multiplier stages of the first symmetric bridge arm respectively. The first and third ends of each of the voltage multiplier stages of the second symmetric bridge arm are connected to the first end of the AC stage via the second and first inductors respectively.

16. The AC-DC power conversion system according to claim 15, further comprising a third inductor and a third symmetric bridge arm, wherein the third symmetric bridge arm includes first and second voltage multiplier stages, and the first and second voltage multiplier stages of the third symmetric bridge arm are substantially the same as the first and second voltage multiplier stages of the first symmetric bridge arm respectively; the first end of each of the voltage multiplier stages of the third symmetric bridge arm is connected to the first end of the AC stage via the third inductor; the third end of each of the voltage multiplier stages of the third symmetric bridge arm is connected to the second end of each of the voltage multiplier stages of the second symmetric bridge arm.

17. The AC-DC power conversion system according to claim 1, wherein, The DC stage includes an output capacitor.

18. An AC-DC power conversion system, comprising: An AC stage, including a switching element, a first end, a second end, a third end and a neutral end; A first inductor; A first voltage multiplier stage and a second voltage multiplier stage, wherein each of the voltage multiplier stages includes a first end, a second end and a third end; A totem-pole rectifier stage, including a second inductor, a third inductor, a first half-bridge arm and a second half-bridge arm, wherein each of the half-bridge arms is connected between the second end of the first voltage multiplier stage and the second end of the second voltage multiplier stage, and each of the half-bridge arms includes a first and a second element connected in series to a common end; and A DC stage, coupled in parallel to the totem-pole rectifier stage, and including a first and a second capacitor connected in series to a common end; Among them, The switching element has a first configuration and a second configuration. In the first configuration, the first end of the AC stage is coupled to the first end of each of the voltage multiplier stages via the first inductor, the first end of the AC stage is coupled to the third end of each of the voltage multiplier stages and the common end of the first half-bridge arm via the second inductor, and the neutral end is coupled to the common end of the second half-bridge arm; In the second configuration, the first end of the AC stage is coupled to the first end of each of the voltage multiplier stages via the first inductor, the second end of the AC stage is coupled to the common end of the first half-bridge arm via the second inductor, the third end of the AC stage is coupled to the common end of the second half-bridge arm via the third inductor, and the neutral end is coupled to the common end of the DC stage, wherein each of the voltage multiplier stages includes a capacitor and first, second and third switches, wherein the first and second switches of the voltage multiplier stage are connected in series between the first and second ends of the voltage multiplier stage, the first and second switches of the voltage multiplier stage are connected to a common end, and the third switch and the capacitor of the voltage multiplier stage are connected in series between the common end of the first and second switches and the third end of the voltage multiplier stage.

19. The AC-DC power conversion system according to claim 18, wherein, The third switch operates at a signal frequency of the AC stage.

20. The AC-DC power conversion system according to claim 18, wherein, The third switch of each of the voltage multiplier stages comprises a bidirectional switch.

21. The AC-DC power conversion system according to claim 20, wherein, The bidirectional switch comprises two power semiconductor switch devices connected together, and the body diodes of the two power semiconductor switch devices are connected in opposite polarities.

22. The AC-DC power conversion system according to claim 18, wherein, The switching element comprises a relay switch.

23. The AC-DC power conversion system according to claim 18, wherein, In the first configuration, the AC stage receives a single-phase AC input power supply.

24. The AC-DC power conversion system according to claim 18, wherein, In the second configuration, the AC stage receives a three-phase AC input power supply.

25. A battery charger comprising the AC-DC power conversion system according to claim 18.

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