Non-isolated AC voltage regulation circuit and control method thereof

Abstract

The invention relates to a non-isolated alternating current voltage regulation circuit, which comprises an input end, an output end, a first switch bridge arm, a second switch bridge arm and a voltage transformation circuit, the output end comprises first to third connecting ends. The first switch bridge arm and the second switch bridge arm comprise a first switch, a second switch, a third switch and a fourth switch which are sequentially connected in series between the first connecting end and the third connecting end. The first and second switches are connected to form a first node, and the third and fourth switches are connected to form a second node. The voltage transformation circuit comprises a resonance circuit and a soft switching circuit. The resonance circuit is connected between the first node and the second node. The soft switching circuit comprises a fourth connecting end and a fifth connecting end. The fourth connecting end is coupled to one of the first node and the second node, and the fifth connecting end is coupled to one of the first connecting end, the second connecting end and the third connecting end, or the fourth connecting end is coupled to a main resonant inductor of the resonant circuit, and the fifth connecting end is coupled to the second connecting end. The invention further relates to a related control method.

Description

Technical Field

[0001] This case pertains to the field of power conversion, specifically a non-isolated AC voltage regulation circuit and its control method. Background Technology

[0002] Many loads, such as electric vehicles, require AC voltage regulator circuits to first convert the AC voltage into the load voltage required by the load, and then operate using the load voltage provided by the AC voltage regulator circuit. Currently, AC voltage regulator circuits used in high-power applications commonly include autotransformers, which regulate the load voltage by switching the taps of the autotransformer.

[0003] However, since autotransformers are usually power frequency transformers (i.e., transformers with an operating frequency of 50Hz / 60Hz), the core of an autotransformer is large and the windings are numerous, resulting in both the autotransformer and the AC voltage regulating circuit using it having disadvantages such as large overall size and heavy weight.

[0004] In view of this, it is necessary to provide a non-isolated AC voltage regulating circuit and its control method to solve the problems faced by the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a non-isolated AC voltage regulation circuit and its control method, which can reduce size and weight, lower cost, reduce electromagnetic interference, and improve conversion efficiency and power density.

[0006] According to the concept of this invention, a non-isolated AC voltage regulating circuit is provided, comprising an input terminal, an output terminal, a first switching bridge arm, a second switching bridge arm, and a transformer circuit. The input terminal includes a positive connection terminal and a negative connection terminal for receiving AC voltage. The output terminal includes a first connection terminal, a second connection terminal, and a third connection terminal, wherein the third connection terminal is coupled to the negative connection terminal. The first switching bridge arm is coupled between the first and second connection terminals and includes a first switch and a second switch connected in series, wherein the first and second switches are connected to form a first node. The second switching bridge arm is coupled between the second and third connection terminals and includes a third switch and a fourth switch connected in series, wherein the third and fourth switches are connected to form a second node. The transformer circuit includes a resonant circuit and a soft-switching circuit. The resonant circuit includes at least one main resonant inductor and at least one main resonant capacitor, which are connected in series between the first node and the second node. The soft-switching circuit includes a fourth connection terminal and a fifth connection terminal, wherein the fourth connection terminal is coupled to at least one of the first node and the second node, and the fifth connection terminal is coupled to one of the first connection terminal, the second connection terminal, and the third connection terminal; or the fourth connection terminal is coupled to at least one main resonant inductor, and the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is designed to provide soft-switching conditions during the on / off moments of the first switch, the second switch, the third switch, and the fourth switch.

[0007] According to another concept of this invention, a non-isolated AC voltage regulating circuit is provided, comprising an input terminal, an output terminal, a first switching bridge arm, a second switching bridge arm, and a transformer circuit. The input terminal includes a positive connection terminal and a negative connection terminal for receiving AC voltage. The output terminal includes a first connection terminal, a second connection terminal, and a third connection terminal, wherein the third connection terminal is coupled to the negative connection terminal. The first switching bridge arm is coupled between the first and second connection terminals and includes a first switch and a second switch connected in series, wherein the first and second switches are connected to form a first node. The second switching bridge arm is coupled between the second and third connection terminals and includes a third switch and a fourth switch connected in series, wherein the third and fourth switches are connected to form a second node. The transformer circuit includes a resonant circuit and a soft-switching circuit. The resonant circuit includes at least one main resonant inductor and at least one main resonant capacitor, which are connected in series between the first node and the second node. The soft-switching circuit includes an auxiliary resonant inductor, a fourth connection terminal, and a fifth connection terminal. The auxiliary resonant inductor is coupled between the fourth and fifth connection terminals. The fourth connection terminal is coupled to at least one main resonant inductor, and the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is designed to provide soft-switching conditions during the on / off moments of the first, second, third, and fourth switches.

[0008] According to another concept of this case, a control method is provided for a non-isolated AC voltage regulating circuit. The non-isolated AC voltage regulating circuit includes an input terminal, an output terminal, a first switch bridge arm, a second switch bridge arm, and a transformer circuit. The input terminal includes a positive connection terminal and a negative connection terminal for receiving AC voltage. The output terminal includes a first connection terminal, a second connection terminal, and a third connection terminal, with the third connection terminal coupled to the negative connection terminal. The first switch bridge arm is coupled between the first and second connection terminals and includes a first switch and a second switch connected in series to form a first node. The second switch bridge arm is coupled between the second and third connection terminals and includes a third switch and a fourth switch connected in series to form a second node. The transformer circuit includes a resonant circuit and a soft-switching circuit. The resonant circuit includes at least one main resonant inductor and at least one main resonant capacitor, which are connected in series between the first node and the second node. Between the points, the soft-switching circuit includes a fourth connection terminal and a fifth connection terminal, wherein the fourth connection terminal is coupled to one of the first node and the second node, and the fifth connection terminal is coupled to one of the first connection terminal, the second connection terminal and the third connection terminal, or the fourth connection terminal is coupled to at least one main resonant inductor and the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is designed to provide soft-switching conditions at the moment when the first switch, the second switch, the third switch and the fourth switch are turned on / off, wherein the first switch includes a first transistor switch and a second transistor switch, the second switch includes a third transistor switch and a fourth transistor switch, the third switch includes a fifth transistor switch and a sixth transistor switch, and the fourth switch includes a seventh transistor switch and an eighth transistor switch. The first transistor switch, the second transistor switch, the third transistor switch, the fourth transistor switch, the fifth transistor switch, the sixth transistor switch, the seventh transistor switch and the eighth transistor switch are connected in series between the first connection terminal and the third connection terminal. The control method of this case includes the following steps: (S1) When the AC voltage is positive, the first transistor switch and the fifth transistor switch are switched on or off synchronously, the third transistor switch and the seventh transistor switch are switched on or off synchronously, the first transistor switch and the third transistor switch are complementary, and the second transistor switch, the fourth transistor switch, the sixth transistor switch and the eighth transistor switch are continuously on; and (S2) When the AC voltage is negative, the second transistor switch and the sixth transistor switch are switched on or off synchronously, the fourth transistor switch and the eighth transistor switch are switched on or off synchronously, the second transistor switch and the fourth transistor switch are complementary, and the first transistor switch, the third transistor switch, the fifth transistor switch and the seventh transistor switch are continuously on. Attached Figure Description

[0009] Figure 1This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the first embodiment of this case.

[0010] Figure 2 for Figure 1 The diagram shows the control framework of the control circuit.

[0011] Figure 3 for Figure 1 The diagram shows the waveforms of the operating parameters of a non-isolated AC voltage regulator circuit.

[0012] Figure 4 When the AC voltage is positive, Figure 1 The diagram shows the timing of operation of the first to the eighth transistor switches.

[0013] Figure 5 When the AC voltage is negative, Figure 1 The diagram shows the timing of operation of the first to the eighth transistor switches.

[0014] Figure 6 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the second embodiment of this case.

[0015] Figure 7 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the third embodiment of this case.

[0016] Figure 8 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the fourth embodiment of this case.

[0017] Figure 9 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the fifth embodiment of this case.

[0018] Figure 10 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the sixth embodiment of this case.

[0019] Figure 11 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the seventh embodiment of this case.

[0020] Figure 12 This is a flowchart illustrating the steps of the control method in a preferred embodiment of this case.

[0021] List of reference numerals

[0022] 1, 1a, 1b, 1c, 1d, 1e, 1f: Non-isolated AC voltage regulating circuits

[0023] B1: First switch bridge arm

[0024] B2: Second switch bridge arm

[0025] 2: Transformer circuit

[0026] Vin+: Positive connection end

[0027] Vin-: Negative connection end

[0028] Vac: AC voltage

[0029] T1: First connection end

[0030] T2: Second connection end

[0031] T3: Third connection end

[0032] Z1: First Load

[0033] Z2: Second Load

[0034] Vac1: First output voltage

[0035] Vac2: Second output voltage

[0036] SW1: First switch

[0037] SW2: Second switch

[0038] SW3: Third switch

[0039] SW4: Fourth Switch

[0040] A: First node

[0041] B: Second node

[0042] 20, 20a, 20b, 20c: Resonant circuits

[0043] 21, 21a, 21b, 21c: Soft-switching circuits

[0044] 211: Fourth connection end

[0045] 212: Fifth connection end

[0046] L1: First main resonant inductor

[0047] L2: Second main resonant inductor

[0048] C1: First main resonant capacitor

[0049] C2: Second main resonant capacitor

[0050] L3: Auxiliary resonant inductor

[0051] Ca: Auxiliary resonant capacitor

[0052] 3: Control circuit

[0053] G11: First transistor switch

[0054] G12: Second transistor switch

[0055] G21: Third transistor switch

[0056] G22: Fourth transistor switch

[0057] G31: Fifth Transistor Switch

[0058] G32: Sixth Transistor Switch

[0059] G41: Seventh Transistor Switch

[0060] G42: Eighth Transistor Switch

[0061] 30: Comparator

[0062] 31: Inverter

[0063] 32: Dead-time circuit

[0064] 33: First switching circuit

[0065] 34: Second switching circuit

[0066] 35: First fixed high-level circuit

[0067] 36: Second fixed high-level circuit

[0068] ILr: Main resonant current

[0069] Vcr: Capacitor voltage

[0070] Is: Auxiliary resonant current

[0071] Ig: Input current

[0072] Iz1: First load current

[0073] Iz2: Second load current

[0074] 4: Output filter circuit

[0075] Cf1: First filter capacitor

[0076] Cf2: Second filter capacitor

[0077] Cf3: Third filter capacitor

[0078] Cf4: Fourth filter capacitor

[0079] Lf: Output filter inductor

[0080] Lin: Input filter inductor Detailed Implementation

[0081] Some typical embodiments that embody the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations in different forms, all of which do not depart from the scope of this invention, and the descriptions and illustrations therein are for illustrative purposes only and not intended to limit this invention.

[0082] For example, different embodiments in this disclosure may use repeated reference numerals and / or designations. These repetitions are for simplification and clarity and are not intended to limit the relationships between the various embodiments and / or the described appearance structures. Furthermore, when an element is referred to as "connected to" or "coupled to" another element, it may be directly connected to or coupled to the other element, or there may be intervening components. Additionally, it is understood that while terms such as "first," "second," and "third" may be used in the claims to describe different elements, these elements should not be limited by these terms, and the elements described accordingly in the embodiments are represented by different element symbols. These terms are used to distinguish different components. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the embodiments. The term "and / or" as thus used includes any or all combinations of one or more of the related listed states.

[0083] The non-isolated AC voltage regulator circuit of this embodiment includes an input terminal, an output terminal, a first switch bridge arm, a second switch bridge arm, and a transformer circuit. The input terminal includes a positive connection terminal and a negative connection terminal for receiving AC voltage. The output terminal includes a first connection terminal, a second connection terminal, and a third connection terminal, wherein the third connection terminal is coupled to the negative connection terminal. The first connection terminal is coupled to the positive connection terminal. The first switch bridge arm is coupled between the first and second connection terminals and includes a first switch and a second switch connected in series to form a first node. The second switch bridge arm is coupled between the second and third connection terminals and includes a third switch and a fourth switch connected in series to form a second node. The transformer circuit includes a resonant circuit and a soft-switching circuit. The resonant circuit includes at least one main resonant inductor and at least one main resonant capacitor, which are connected in series between the first node and the second node. The soft-switching circuit includes a fourth connection terminal and a fifth connection terminal, wherein the fourth connection terminal is coupled to at least one of the first node and the second node, and the fifth connection terminal is coupled to one of the first connection terminal, the second connection terminal, and the third connection terminal; or the fourth connection terminal is coupled to at least one main resonant inductor, and the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is designed to provide soft-switching conditions at the moment the first switch, the second switch, the third switch, and the fourth switch are turned on / off. Using the above-described transformer circuit architecture, the non-isolated AC voltage regulating circuit of this embodiment can replace the autotransformer used in traditional AC voltage regulating circuits by utilizing the transformer circuit in conjunction with the first and second switch bridge arms to achieve the function of voltage transformation. Furthermore, since an autotransformer is not required, the non-isolated AC voltage regulating circuit of this embodiment can achieve the effects of reducing size and weight. The following will further explain the various embodiments of the non-isolated AC voltage regulator circuit in this case. The circuit topology and operation of the non-isolated AC voltage regulator circuits mentioned later are similar, so the same symbols are used to indicate the similarity of the circuit architecture and operation of the representative components, and will not be described again.

[0084] Please see Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 ,in Figure 1 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the first embodiment of this case. Figure 2 for Figure 1 The diagram shows the control framework of the control circuit. Figure 3 for Figure 1 The diagram shows the waveforms of the operating parameters of a non-isolated AC voltage regulator circuit. Figure 4 When the AC voltage is positive, Figure 1 The timing diagram shown is for the operation of the first to eighth transistor switches. Figure 5When the AC voltage is negative, Figure 1 The diagram shows the timing of operation of the first to eighth transistor switches. In this embodiment, the non-isolated AC voltage regulator circuit 1 can be coupled to an AC power supply and at least one load to convert the AC voltage Vac provided by the AC power supply to output a single output voltage or output voltages of different values.

[0085] The non-isolated AC voltage regulator circuit 1 may be, but is not limited to, having bidirectional power conversion function, and includes an input terminal, an output terminal, a first switching bridge arm B1, a second switching bridge arm B2, and a transformer circuit 2. The input terminal includes a positive connection terminal Vin+ and a negative connection terminal Vin-, used to receive the AC voltage Vac provided by the AC power supply. The output terminal includes a first connection terminal T1, a second connection terminal T2, and a third connection terminal T3, wherein the third connection terminal T3 is coupled to the negative connection terminal Vin-, and the first connection terminal T1 is coupled to the positive connection terminal Vin+; and corresponding loads can be connected between the first connection terminal T1 and the second connection terminal T2, between the second connection terminal T2 and the third connection terminal T3, and between the first connection terminal T1 and the third connection terminal T3. Figure 1 In one embodiment, a first load Z1 is coupled between a first connection terminal T1 and a second connection terminal T2, and a second load Z2 is coupled between a second connection terminal T2 and a third connection terminal T3. In some embodiments, a first output voltage Vac1 can be provided between the first connection terminal T1 and the second connection terminal T2, a second output voltage Vac2 can be provided between the second connection terminal T2 and the third connection terminal T3, and a third output voltage can be provided between the first connection terminal T1 and the third connection terminal T3, the third output voltage being equal to the sum of the first output voltage Vac1 and the second output voltage Vac2.

[0086] The first switch arm B1 is coupled between the first connection terminal T1 and the second connection terminal T2, and includes a first switch SW1 and a second switch SW2 connected in series, forming a first node A. The second switch arm B2 is coupled between the second connection terminal T2 and the third connection terminal T3, and includes a third switch SW3 and a fourth switch SW4 connected in series, forming a second node B. In this embodiment, the first switch arm B1 and the second switch arm B2 each include a half-bridge arm. The transformer circuit 2 includes a resonant circuit 20 and a soft-switching circuit 21. The resonant circuit 20 realizes power transmission between the first switch arm B1 and the second switch arm B2 through resonance, and includes a first main resonant inductor L1, a second main resonant inductor L2, a first main resonant capacitor C1, and a second main resonant capacitor C2. The first end of the first main resonant capacitor C1 is coupled to the first node A, and the second end of the first main resonant capacitor C1 is coupled to the first end of the first main resonant inductor L1. The second terminal of the first main resonant inductor L1 is coupled to the first terminal of the second main resonant inductor L2. The second terminal of the second main resonant inductor L2 is coupled to the first terminal of the second main resonant capacitor C2. The second terminal of the second main resonant capacitor C2 is coupled to the second node B.

[0087] The soft-switching circuit 21 includes a fourth connection terminal 211 and a fifth connection terminal 212. The fourth connection terminal 211 is coupled to the second terminal of the first main resonant inductor L1 and the first terminal of the second main resonant inductor L2. The fifth connection terminal 212 is coupled to the second connection terminal T2. In some embodiments, the soft-switching circuit 21 includes an auxiliary resonant inductor L3, the first terminal of which is coupled to the fourth connection terminal 211, and the second terminal of which is coupled to the fifth connection terminal 212.

[0088] In some embodiments, the resonant circuit 20 and the auxiliary resonant inductor L3 can be integrated into a magnetic module. In other embodiments, the first main resonant inductor L1, the second main resonant inductor L2, and the auxiliary resonant inductor L3 can be integrated into a single magnetic module.

[0089] In some embodiments, the non-isolated AC voltage regulator circuit 1 further includes a control circuit 3, which is coupled to the control terminals of the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4, respectively. The control circuit 3 is configured to control the operation of the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4. The control circuit 3 can also be coupled to the input terminal of the non-isolated AC voltage regulator circuit 1 to measure whether the AC voltage Vac is positive or negative, and control the operation of the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4 based on the measurement result.

[0090] In some embodiments, the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4 are each composed of two transistor switches connected back-to-back (i.e., the sources of the two transistor switches are connected together), as shown below. Figure 1 As shown, the first switch SW1 includes a first transistor switch G11 and a second transistor switch G12 connected back-to-back; the second switch SW2 includes a third transistor switch G21 and a fourth transistor switch G22 connected back-to-back; the third switch SW3 includes a fifth transistor switch G31 and a sixth transistor switch G32 connected back-to-back; and the fourth switch SW4 includes a seventh transistor switch G41 and an eighth transistor switch G42 connected back-to-back. Of course, in other embodiments, the first switch SW1, the second switch SW2, the third switch SW3, and the fourth switch SW4 can each be replaced with a single bidirectional transistor switch.

[0091] Please see Figure 4 and cooperate Figure 1 When the AC voltage Vac measured by control circuit 3 is positive, control circuit 3 controls the first transistor switch G11 and the fifth transistor G31 to simultaneously switch on or off at high frequency, and controls the third transistor switch G21 and the seventh transistor G41 to simultaneously switch on or off at high frequency. The first transistor switch G11 and the third transistor switch G21 have complementary 50% duty cycles, and control circuit 3 keeps the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32, and the eighth transistor switch G42 continuously on. Please refer to [link / reference]. Figure 5 In conjunction with step 1, when the AC voltage Vac measured by control circuit 3 is negative, control circuit 3 controls the second transistor switch G12 and the sixth transistor switch G32 to synchronously switch on or off at high frequency, and controls the fourth transistor switch G22 and the eighth transistor switch G42 to synchronously switch on or off at high frequency. The second transistor switch G12 and the fourth transistor switch G22 are controlled to have complementary 50% duty cycles, and control circuit 3 controls the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41 to remain continuously on. In some embodiments, a dead time may exist between the first transistor switch G11 and the third transistor switch G21, and a dead time may exist between the second transistor switch G12 and the fourth transistor switch G22.

[0092] Please see Figure 2In some embodiments, the control circuit 3 includes a comparator 30, an inverter (NOT gate) 31, two sets of dead-time circuits 32, a first switching circuit 33, a second switching circuit 34, a first fixed high-level circuit 35, and a second fixed high-level circuit 36. The first terminal of the comparator 30 is coupled to the input terminal to capture a triangular wave signal of the AC voltage Vac, and the second terminal of the comparator 30 is connected to a reference voltage source to receive a reference voltage. The comparator 30 is configured to compare the triangular wave signal with the reference voltage and correspondingly generate a periodic pulse-width modulation (PWM) signal, which is output through the output terminal of the comparator 30. The inverter 31 is connected to the output terminal of the comparator 30, receives the aforementioned PWM signal, and outputs an inverted PWM signal. One set of the two sets of dead-time circuits 32 is connected to the inverter 31 to receive the aforementioned inverted PWM signal, and the other set of the two sets of dead-time circuits 32 is directly connected to the output terminal of the comparator 30 to receive the aforementioned PWM signal. Two sets of dead-time circuits 32 insert a turn-off delay into their respective received inverted pulse width modulation (PWM) signals and pulse width modulation (PWM) signals to generate a pair of complementary PWM signals with dead time. A first switching circuit 33 is connected between the two sets of dead-time circuits 32 and the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41, and is configured to switch these transistor switches on or off according to the received PWM signals. A second switching circuit 34 is connected between the two sets of dead-time circuits 32 and the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32, and the eighth transistor switch G42, and is configured to switch these transistor switches on or off according to the received PWM signals. A first fixed high-level circuit 35 is connected to the first switching circuit 33 and is configured to keep the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41 continuously on according to the switching action of the first switching circuit 33. The second fixed high-level circuit 36 ​​is connected to the second switching circuit 34 and is configured to keep the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32 and the eighth transistor switch G42 continuously on according to the switching action of the second switching circuit 34.

[0093] The operation of control circuit 3 will be further explained below. Please refer to [link / reference]. Figure 2 and cooperate Figure 1 and Figure 3First, the comparator 30 of the control circuit 3 compares the triangular wave signal with a constant DC voltage (e.g., a reference voltage of 0.5V) to generate a periodic basic pulse width modulation signal. The basic pulse width modulation signal is then used by the inverter (NOT gate) 31 of the control circuit 3 to generate an inverted pulse width modulation signal, which is then input to two sets of dead-time circuits 32. The dead-time circuits 32 insert a turn-off delay into each of the two pulse width modulation signals to generate a pair of complementary pulse width modulation signals with dead time. When the AC voltage Vac is positive, the first switching circuit 33 of the control circuit 3 conducts the path between the corresponding dead-time circuit 32 and the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41. This allows the complementary pulse width modulation signal with dead time to be provided to the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41, causing these transistor switches to perform high-frequency switching of turning on or off. Meanwhile, the second switching circuit 34 of the control circuit 3 conducts the path between the second fixed high-level circuit 36 ​​of the control circuit 3 and the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32, and the eighth transistor switch G42. This causes the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32, and the eighth transistor switch G42 to remain on due to the high-level signal output by the second fixed high-level circuit 36. Figure 4 As shown. When the AC voltage Vac is negative, the first switching circuit 33 of the control circuit 3 opens the path between the first fixed high-level circuit 35 and the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41, so that the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31, and the seventh transistor switch G41 are continuously turned on due to the high-level signal output by the first fixed high-level circuit 35. Meanwhile, the second switching circuit 34 of the control circuit 3 opens the path between the corresponding dead-time circuit 32 and the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32, and the eighth transistor switch G42, so that the complementary pulse width modulation signal with dead time is provided to the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32, and the eighth transistor switch G42, causing these transistor switches to perform high-frequency switching of turning on or off, i.e. Figure 5 As shown.

[0094] exist Figure 3The diagram shows the main resonant current ILr flowing through the main resonant inductor (e.g., the first main resonant inductor L1) of the resonant circuit 20, the capacitor voltage Vcr of the main resonant capacitor (the first main resonant capacitor C1 or the second main resonant capacitor C2) of the resonant circuit 20, the auxiliary resonant current Is flowing through the auxiliary resonant inductor L3 of the soft-switching circuit 21, the first output voltage Vac1 between the first connection terminal T1 and the second connection terminal T2 of the output terminal of the non-isolated AC voltage regulator circuit 1, the second output voltage Vac2 between the second connection terminal T2 and the third terminal T3 of the output terminal, the input current Ig of the input terminal of the non-isolated AC voltage regulator circuit 1, the first load current Iz1 flowing through the first load Z1, and the second load current Iz2 flowing through the second load Z2.

[0095] In some embodiments, the non-isolated AC voltage regulator circuit 1 may further include an output filter circuit 4 for filtering and regulating the output of the non-isolated AC voltage regulator circuit 1. The output filter circuit 4 includes a first filter capacitor Cf1, a second filter capacitor Cf2, a third filter capacitor Cf3, a fourth filter capacitor Cf4, and an output filter inductor Lf. The first terminal of the first filter capacitor Cf1 is coupled to the first connection terminal T1, and the second terminal of the first filter capacitor Cf1 is coupled to the fifth connection terminal 212 of the soft-switching circuit 21. The first terminal of the second filter capacitor Cf2 is coupled to the first connection terminal T1, and the second terminal of the second filter capacitor Cf2 is coupled to the second connection terminal T2. The first terminal of the third filter capacitor Cf3 is coupled to the fifth connection terminal 212 of the soft-switching circuit 21, and the second terminal of the third filter capacitor Cf3 is coupled to the third connection terminal T3. The first terminal of the fourth filter capacitor Cf4 is coupled to the second connection terminal T2, and the second terminal of the third filter capacitor Cf3 is coupled to the third connection terminal T3. The output filter inductor Lf is coupled between the fifth connection terminal 212 and the second connection terminal T2 of the soft-switching circuit 21.

[0096] In some embodiments, the non-isolated AC voltage regulator circuit 1 may further include an input filter inductor Lin, coupled between the positive connection terminal Vin+ and the first switch bridge arm B1, for filtering and voltage regulation.

[0097] In this embodiment, the non-isolated AC voltage regulator circuit 1 uses a transformer circuit 2 in conjunction with the first switching arm B1 and the second switching arm B2 to replace the autotransformer used in traditional AC voltage regulator circuits, thereby achieving the function of voltage transformation. Since an autotransformer is not required, the size and weight are reduced. Furthermore, because the switching of the first switching arm B1 and the second switching arm B2 utilizes soft-switching operation, the switching cost of the first switching arm B1 and the second switching arm B2 is reduced, electromagnetic interference (EMI) is decreased, and the conversion efficiency and power density of the non-isolated AC voltage regulator circuit 1 are improved. Moreover, since the control circuit 3 of the non-isolated AC voltage regulator circuit 1 only needs a voltage sensor to determine the polarity of the AC voltage Vac, the control circuit 3 does not need to use a more complex controller architecture, such as a microcontroller unit or a digital signal processor. Furthermore, the non-isolated AC voltage regulator circuit 1 of this invention, through its circuit architecture and operation, can support unbalanced loads and provide both active and reactive power. The same functions of the non-isolated AC voltage regulator circuit 1 in the above embodiment also exist in the different embodiments of non-isolated AC voltage regulator circuits mentioned later, and will not be repeated hereafter.

[0098] Please see Figure 6 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit of the second embodiment of this case. Compared to the non-isolated AC voltage regulator circuit 1a of this embodiment... Figure 1 The difference in the non-isolated AC voltage regulator circuit 1 shown is that the resonant circuit 20a of the non-isolated AC voltage regulator circuit 1a is changed to include a first main resonant inductor L1, a first main resonant capacitor C1, and a second main resonant capacitor C2. The first terminal of the first main resonant capacitor C1 of the resonant circuit 20a is coupled to the first node A, and the second terminal of the first main resonant capacitor C1 is coupled to the first terminal of the first main resonant inductor L1. The second terminal of the first main resonant inductor L1 is coupled to the first terminal of the second main resonant capacitor C2 and the fourth connection terminal 211 of the soft-switching circuit 21. The second terminal of the second main resonant capacitor C2 is coupled to the second node B. In some embodiments, the resonant circuit 20a and the auxiliary resonant inductor L3 can be integrated into a magnetic module. In other embodiments, the first main resonant inductor L1 and the auxiliary resonant inductor L3 can be integrated into a single-piece magnetic module.

[0099] Please see Figure 7 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit of the third embodiment of this case. Compared to the non-isolated AC voltage regulator circuit 1b of this embodiment... Figure 1The difference in the non-isolated AC voltage regulator circuit 1 shown is that the resonant circuit 20b of the non-isolated AC voltage regulator circuit 1b is replaced with a first main resonant inductor L1, a first main resonant capacitor C1, and a second main resonant capacitor C2. The first terminal of the first main resonant capacitor C1 is coupled to the first node A, and the second terminal of the first main resonant capacitor C1 is coupled to the first terminal of the first main resonant inductor L1 and the fourth connection terminal 211 of the soft-switching circuit 21. The second terminal of the first main resonant inductor L1 is coupled to the first terminal of the second main resonant capacitor C2. The second terminal of the second main resonant capacitor C2 is coupled to the second node B. In some embodiments, the resonant circuit 20b and the auxiliary resonant inductor L3 can be integrated into a magnetic module. In other embodiments, the first main resonant inductor L1 and the auxiliary resonant inductor L3 can be integrated into a single-piece magnetic module.

[0100] Please see Figure 8 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the fourth embodiment of this case. Compared to... Figure 1 The difference in the non-isolated AC voltage regulator circuit 1 shown is that the resonant circuit 20c of the non-isolated AC voltage regulator circuit 1c is changed to include a first main resonant inductor L1 and a first main resonant capacitor C1. The first main resonant inductor L1 and the first main resonant capacitor C1 are connected in series between the first node A and the second node B. For example, the first end of the first main resonant inductor L1 is coupled to the first node A, the second end of the first main resonant inductor L1 is coupled to the first end of the first main resonant capacitor C1, and the second end of the first main resonant capacitor C1 is coupled to the second node B.

[0101] Furthermore, in this embodiment, the soft-switching circuit 21a of the non-isolated AC voltage regulator circuit 1c is modified to include an auxiliary resonant inductor L3 and an auxiliary resonant capacitor Ca. The auxiliary resonant inductor L3 and the auxiliary resonant capacitor Ca are connected in series between the fourth connection terminal 211 and the fifth connection terminal 212 of the soft-switching circuit 21a. For example, the first end of the auxiliary resonant inductor L3 is coupled to the fourth connection terminal 211 of the soft-switching circuit 21a and the first node A, the second end of the auxiliary resonant inductor L3 is coupled to the first end of the auxiliary resonant capacitor Ca, and the second end of the auxiliary resonant capacitor Ca is coupled to the fifth connection terminal 212 of the soft-switching circuit 21a and the second connection terminal T2.

[0102] Furthermore, in this embodiment, the fourth connection terminal 211 of the soft-switching circuit 21a is coupled to the first node A, and the fifth connection terminal 212 of the soft-switching circuit 21a is coupled to the second connection terminal T2.

[0103] In addition, in this embodiment, the first switch SW1 and the second switch SW2 of the first switch bridge arm B1 and the third switch SW3 and the fourth switch SW4 of the second switch bridge arm B2 are replaced with a single bidirectional transistor switch, but this is not a limitation and may also include two transistor switches connected back to back.

[0104] Please see Figure 9 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit of the fifth embodiment of this case. The non-isolated AC voltage regulator circuit 1d of this embodiment is compared to... Figure 8 The difference between the non-isolated AC voltage regulator circuit 1c shown is that the fourth connection terminal 211 of the soft-switching circuit 21b of the non-isolated AC voltage regulator circuit 1d is coupled to the first node A, and the fifth connection terminal 212 of the soft-switching circuit 21b is coupled to the first connection terminal T1.

[0105] Please see Figure 10 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the sixth embodiment of this case. The non-isolated AC voltage regulator circuit 1e in this embodiment is compared to... Figure 8 The difference between the non-isolated AC voltage regulator circuit 1c shown is that the fourth connection terminal 211 of the soft-switching circuit 21c of the non-isolated AC voltage regulator circuit 1e is coupled to the second node B, and the fifth connection terminal 212 of the soft-switching circuit 21c is coupled to the second connection terminal T2.

[0106] Please see Figure 11 This is a schematic diagram of the circuit structure of the non-isolated AC voltage regulator circuit in the seventh embodiment of this case. Compared to... Figure 10 The difference between the non-isolated AC voltage regulator circuit 1e shown is that the fourth connection terminal 211 of the soft-switching circuit 21d of the non-isolated AC voltage regulator circuit 1d is coupled to the second node B, and the fifth connection terminal 212 of the soft-switching circuit 21d is coupled to the third connection terminal T3. Figure 12 This is a schematic flowchart illustrating the steps of a control method according to an embodiment of this invention. The control method of this invention is applicable to the aforementioned non-isolated AC voltage regulating circuits 1, 1a, 1b, 1c, 1d, 1e, 1f, and includes the following steps.

[0107] In step S1, when the AC voltage Vac measured by the control circuit 3 is positive, the control circuit 3 controls the first transistor switch G11 and the fifth transistor switch G31 to switch on or off synchronously, and controls the third transistor switch G21 and the seventh transistor switch G41 to switch on or off synchronously. The first transistor switch G11 and the third transistor switch G21 are complementary, and the control circuit 3 controls the second transistor switch G12, the fourth transistor switch G22, the sixth transistor switch G32 and the eighth transistor switch G42 to remain on.

[0108] In step S2, when the AC voltage Vac measured by the control circuit 3 is negative, the control circuit 3 controls the second transistor switch G12 and the sixth transistor switch G32 to switch on or off synchronously, controls the fourth transistor switch G22 and the eighth transistor switch G42 to switch on or off synchronously, controls the second transistor switch G12 and the fourth transistor switch G22 to complement each other, and the control circuit 3 controls the first transistor switch G11, the third transistor switch G21, the fifth transistor switch G31 and the seventh transistor switch G41 to remain on.

[0109] In summary, this invention provides a non-isolated AC voltage regulator circuit. This non-isolated AC voltage regulator circuit utilizes a transformer circuit in conjunction with a first switching bridge arm and a second switching bridge arm to replace the autotransformer used in traditional AC voltage regulator circuits, thereby achieving the voltage transformation function. Furthermore, since an autotransformer is not required, it reduces size and weight. Moreover, this non-isolated AC voltage regulator circuit also achieves cost reduction, reduced electromagnetic interference, and improved conversion efficiency and power density.

Claims

1. A non-isolated AC voltage regulating circuit, comprising: An input terminal, including a positive connection terminal and a negative connection terminal, is used to receive an AC voltage; An output terminal includes a first connection terminal, a second connection terminal and a third connection terminal, wherein the third connection terminal is coupled to the negative connection terminal; A first switch bridge arm is coupled between the first connection terminal and the second connection terminal, and includes a first switch and a second switch connected in series, the first switch and the second switch being connected to form a first node; A second switch bridge arm, coupled between the second connection terminal and the third connection terminal, and comprising a third switch and a fourth switch connected in series, the third switch and the fourth switch being connected to form a second node; and A transformer circuit, comprising: A resonant circuit includes at least one main resonant inductor and at least one main resonant capacitor, wherein the at least one main resonant inductor and the at least one main resonant capacitor are connected in series between the first node and the second node; and A soft-switching circuit includes a fourth connection terminal and a fifth connection terminal, wherein, The fourth connection terminal is coupled to at least one of the first node and the second node, while the fifth connection terminal is coupled to one of the first connection terminal, the second connection terminal, and the third connection terminal, or The fourth connection terminal is coupled to the at least one main resonant inductor, while the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is used to provide soft-switching conditions at the moment when the first switch, the second switch, the third switch and the fourth switch are turned on / off.

2. The non-isolated AC voltage regulating circuit as described in claim 1 further includes a control circuit coupled to the first switch, the second switch, the third switch, and the fourth switch, and configured to control the operation of the first switch, the second switch, the third switch, and the fourth switch, wherein the control circuit is coupled to the input terminal and configured to measure whether the AC voltage is positive or negative, and control the operation of the first switch, the second switch, the third switch, and the fourth switch based on the measurement result.

3. The non-isolated AC voltage regulating circuit as described in claim 1, wherein the first switch bridge arm and the second switch bridge arm each comprise a half-bridge bridge arm, and wherein the first switch, the second switch, the third switch and the fourth switch each comprise two transistor switches connected back-to-back in series.

4. The non-isolated AC voltage regulating circuit as described in claim 3, wherein the first switch comprises a first transistor switch and a second transistor switch, the second switch comprises a third transistor switch and a fourth transistor switch, the third switch comprises a fifth transistor switch and a sixth transistor switch, and the fourth switch comprises a seventh transistor switch and an eighth transistor switch; the first transistor switch, the second transistor switch, the third transistor switch, the fourth transistor switch, the fifth transistor switch, the sixth transistor switch, the seventh transistor switch, and the eighth transistor switch are sequentially connected in series between the first connection terminal and the third connection terminal; wherein when the AC voltage is positive, the first transistor switch and the... The fifth transistor switch synchronously switches on or off, the third transistor switch and the seventh transistor switch synchronously switch on or off, the first transistor switch and the third transistor switch are complementary, and the second transistor switch, the fourth transistor switch, the sixth transistor switch and the eighth transistor switch are continuously on. When the AC voltage is negative, the second transistor switch and the sixth transistor switch synchronously switch on or off, the fourth transistor switch and the eighth transistor switch synchronously switch on or off, the second transistor switch and the fourth transistor switch are complementary, and the first transistor switch, the third transistor switch, the fifth transistor switch and the seventh transistor switch are continuously on.

5. The non-isolated AC voltage regulating circuit as described in claim 1, wherein the soft-switching circuit includes an auxiliary resonant inductor, a first end of the auxiliary resonant inductor being coupled to the fourth connection terminal of the soft-switching circuit, and a second end of the auxiliary resonant inductor being coupled to the fifth connection terminal of the soft-switching circuit.

6. The non-isolated AC voltage regulating circuit as claimed in claim 1, wherein the at least one main resonant inductor includes a first main resonant inductor and a second main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor and a second main resonant capacitor, wherein a first terminal of the first main resonant capacitor is coupled to the first node, a second terminal of the first main resonant capacitor is coupled to a first terminal of the first main resonant inductor, a second terminal of the first main resonant inductor is coupled to a first terminal of the second main resonant inductor, a second terminal of the second main resonant inductor is coupled to a first terminal of the second main resonant capacitor, and a second terminal of the second main resonant capacitor is coupled to the second node, wherein the fourth connection terminal of the soft-switching circuit is coupled to the second terminal of the first main resonant inductor and the first terminal of the second main resonant inductor, and the fifth connection terminal of the soft-switching circuit is coupled to the second connection terminal.

7. The non-isolated AC voltage regulating circuit as claimed in claim 1, wherein the at least one main resonant inductor includes a first main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor and a second main resonant capacitor, wherein a first terminal of the first main resonant capacitor is coupled to the first node, a second terminal of the first main resonant capacitor is coupled to a first terminal of the first main resonant inductor, a second terminal of the first main resonant inductor is coupled to a first terminal of the second main resonant capacitor, a second terminal of the second main resonant capacitor is coupled to the second node, wherein the fourth connection terminal of the soft-switching circuit is coupled to the second terminal of the first main resonant inductor and the first terminal of the second main resonant capacitor, and the fifth connection terminal of the soft-switching circuit is coupled to the second connection terminal.

8. The non-isolated AC voltage regulating circuit as claimed in claim 1, wherein the at least one main resonant inductor includes a first main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor and a second main resonant capacitor, wherein a first terminal of the first main resonant capacitor is coupled to the first node, a second terminal of the first main resonant capacitor is coupled to a first terminal of the first main resonant inductor, a second terminal of the first main resonant inductor is coupled to a first terminal of the second main resonant capacitor, a second terminal of the second main resonant capacitor is coupled to the second node, wherein the fourth connection terminal of the soft-switching circuit is coupled to the first terminal of the first main resonant inductor, and the fifth connection terminal of the soft-switching circuit is coupled to the second connection terminal.

9. The non-isolated AC voltage regulating circuit as described in claim 1, wherein the at least one main resonant inductor includes a first main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor, and the first main resonant inductor and the first main resonant capacitor are connected in series between the first node and the second node.

10. The non-isolated AC voltage regulating circuit as described in claim 9, wherein the soft-switching circuit includes an auxiliary resonant inductor and an auxiliary resonant capacitor, a first end of the auxiliary resonant inductor is coupled to the fourth connection terminal of the soft-switching circuit, a second end of the auxiliary resonant inductor is coupled to a first end of the auxiliary resonant capacitor, and a second end of the auxiliary resonant capacitor is coupled to the fifth connection terminal.

11. The non-isolated AC voltage regulating circuit of claim 10, wherein the fourth connection terminal is coupled to the first node and the fifth connection terminal is coupled to the second connection terminal.

12. The non-isolated AC voltage regulating circuit of claim 10, wherein the fourth connection terminal is coupled to the first node and the fifth connection terminal is coupled to the first connection terminal.

13. The non-isolated AC voltage regulating circuit of claim 10, wherein the fourth connection terminal is coupled to the second node and the fifth connection terminal is coupled to the second connection terminal.

14. The non-isolated AC voltage regulating circuit of claim 10, wherein the fourth connection terminal is coupled to the second node and the fifth connection terminal is coupled to the third connection terminal.

15. A non-isolated AC voltage regulating circuit, comprising: An input terminal, including a positive connection terminal and a negative connection terminal, is used to receive an AC voltage; An output terminal includes a first connection terminal, a second connection terminal and a third connection terminal, wherein the third connection terminal is coupled to the negative connection terminal; A first switch bridge arm is coupled between the first connection terminal and the second connection terminal, and includes a first switch and a second switch connected in series, the first switch and the second switch being connected to form a first node; A second switch bridge arm, coupled between the second connection terminal and the third connection terminal, and comprising a third switch and a fourth switch connected in series, the third switch and the fourth switch being connected to form a second node; and A transformer circuit, comprising: A resonant circuit includes at least one main resonant inductor and at least one main resonant capacitor, wherein the at least one main resonant inductor and the at least one main resonant capacitor are connected in series between the first node and the second node; and A soft-switching circuit includes an auxiliary resonant inductor, a fourth connection terminal, and a fifth connection terminal, wherein the auxiliary resonant inductor is coupled between the fourth connection terminal and the fifth connection terminal, the fourth connection terminal is coupled to at least one main resonant inductor, and the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is configured to provide soft-switching conditions at the moment when the first switch, the second switch, the third switch, and the fourth switch are turned on / off.

16. The non-isolated AC voltage regulating circuit of claim 15 further includes a control circuit coupled to the first switch, the second switch, the third switch and the fourth switch, and configured to control the operation of the first switch, the second switch, the third switch and the fourth switch, wherein the control circuit is coupled to the input terminal and configured to measure whether the AC voltage is positive or negative, and adjust the operation of the first switch, the second switch, the third switch and the fourth switch according to the measurement result.

17. The non-isolated AC voltage regulating circuit as described in claim 15, wherein the first switch arm and the second switch arm each comprise a half-bridge arm, and wherein the first switch, the second switch, the third switch and the fourth switch each comprise two transistor switches connected back-to-back in series.

18. The non-isolated AC voltage regulating circuit of claim 17, wherein the first switch comprises a first transistor switch and a second transistor switch, the second switch comprises a third transistor switch and a fourth transistor switch, the third switch comprises a fifth transistor switch and a sixth transistor switch, the fourth switch comprises a seventh transistor switch and an eighth transistor switch, the first transistor switch, the second transistor switch, the third transistor switch, the fourth transistor switch, the fifth transistor switch, the sixth transistor switch, the seventh transistor switch and the eighth transistor switch are sequentially connected in series between the first connection terminal and the third connection terminal, wherein when the AC voltage is positive, the first transistor switch and The fifth transistor switch synchronously switches on or off, the third transistor switch and the seventh transistor switch synchronously switch on or off, the first transistor switch and the third transistor switch are complementary, and the second transistor switch, the fourth transistor switch, the sixth transistor switch and the eighth transistor switch are continuously on. When the AC voltage is negative, the second transistor switch and the sixth transistor switch synchronously switch on or off, the fourth transistor switch and the eighth transistor switch synchronously switch on or off, the second transistor switch and the fourth transistor switch are complementary, and the first transistor switch, the third transistor switch, the fifth transistor switch and the seventh transistor switch are continuously on.

19. The non-isolated AC voltage regulating circuit of claim 15, wherein the at least one main resonant inductor includes a first main resonant inductor and a second main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor and a second main resonant capacitor, wherein a first terminal of the first main resonant capacitor is coupled to the first node, a second terminal of the first main resonant capacitor is coupled to a first terminal of the first main resonant inductor, a second terminal of the first main resonant inductor is coupled to a first terminal of the second main resonant inductor, a second terminal of the second main resonant inductor is coupled to a first terminal of the second main resonant capacitor, and a second terminal of the second main resonant capacitor is coupled to the second node.

20. The non-isolated AC voltage regulating circuit of claim 15, wherein the at least one main resonant inductor includes a first main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor and a second main resonant capacitor, wherein a first terminal of the first main resonant capacitor is coupled to the first node, a second terminal of the first main resonant capacitor is coupled to a first terminal of the first main resonant inductor, a second terminal of the first main resonant inductor is coupled to a first terminal of the second main resonant capacitor, and a second terminal of the second main resonant capacitor is coupled to the second node.

21. The non-isolated AC voltage regulating circuit of claim 15, wherein the at least one main resonant inductor includes a first main resonant inductor, the at least one main resonant capacitor includes a first main resonant capacitor and a second main resonant capacitor, wherein a first terminal of the first main resonant capacitor is coupled to the first node, a second terminal of the first main resonant capacitor is coupled to a first terminal of the first main resonant inductor, a second terminal of the first main resonant inductor is coupled to a first terminal of the second main resonant capacitor, and a second terminal of the second main resonant capacitor is coupled to the second node.

22. A control method for a non-isolated AC voltage regulating circuit, wherein the non-isolated AC voltage regulating circuit includes an input terminal, an output terminal, a first switch bridge arm, a second switch bridge arm, and a transformer circuit, wherein the input terminal includes a positive connection terminal and a negative connection terminal for receiving an AC voltage, the output terminal includes a first connection terminal, a second connection terminal, and a third connection terminal, the third connection terminal being coupled to the negative connection terminal, wherein the first switch bridge arm is coupled between the first connection terminal and the second connection terminal, and includes a first switch and a transformer circuit connected in series. A second switch, the first switch and the second switch connected to form a first node, the second switch bridge arm coupled between the second connection terminal and the third connection terminal, and including a third switch and a fourth switch connected in series, the third switch and the fourth switch connected to form a second node, wherein the transformer circuit includes a resonant circuit and a soft-switching circuit, the resonant circuit including at least one main resonant inductor and at least one main resonant capacitor, the at least one main resonant inductor and the at least one main resonant capacitor being connected in series between the first node and the second node, wherein the soft-switching circuit... The switching circuit includes a fourth connection terminal and a fifth connection terminal. The fourth connection terminal is coupled to one of the first node and the second node, and the fifth connection terminal is coupled to one of the first connection terminal, the second connection terminal, and the third connection terminal. Alternatively, the fourth connection terminal is coupled to the at least one main resonant inductor, and the fifth connection terminal is coupled to the second connection terminal. The soft-switching circuit is configured to provide soft-switching conditions at the moment the first switch, the second switch, the third switch, and the fourth switch are turned on / off. The first switch includes a first transistor switch and a second transistor switch, the second switch includes a third transistor switch and a fourth transistor switch, the third switch includes a fifth transistor switch and a sixth transistor switch, and the fourth switch includes a seventh transistor switch and an eighth transistor switch. The first transistor switch, the second transistor switch, the third transistor switch, the fourth transistor switch, the fifth transistor switch, the sixth transistor switch, the seventh transistor switch, and the eighth transistor switch are sequentially connected in series between the first connection terminal and the third connection terminal. The control method includes: (S1) When the AC voltage is positive, the first transistor switch and the fifth transistor switch synchronously switch on or off, the third transistor switch and the seventh transistor switch synchronously switch on or off, the first transistor switch and the third transistor switch are complementary, and the second transistor switch, the fourth transistor switch, the sixth transistor switch and the eighth transistor switch remain on; and (S2) When the AC voltage is negative, the second transistor switch and the sixth transistor switch are switched on or off synchronously, the fourth transistor switch and the eighth transistor switch are switched on or off synchronously, the second transistor switch and the fourth transistor switch are complementary, and the first transistor switch, the third transistor switch, the fifth transistor switch and the seventh transistor switch are continuously on.

23. The control method of claim 22, wherein the non-isolated AC voltage regulating circuit further includes a control circuit coupled to the first switch, the second switch, the third switch and the fourth switch, and configured to control the operation of the first switch, the second switch, the third switch and the fourth switch, wherein the control circuit is coupled to the input terminal and configured to measure whether the AC voltage is positive or negative, and adjust the operation of the first switch, the second switch, the third switch and the fourth switch according to the measurement result.

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