TWI899883B - Multi-phase circuit control method and power conversion device - Google Patents

Abstract

A multi-phase circuit control method includes following steps: generating a first control signal and a second control signal to a first phase circuit respectively by a controller; generating a third control signal and a fourth control signal to a second phase circuit respectively by the controller; outputting a two phase voltage to a output terminal of a power conversion device by the first phase circuit and the second circuit; changing a duty cycle of the third control signal to close a first switch of a primary side circuit and a rectifier side circuit of the second phase circuit by the controller when the controller detects that the output voltage is lower than a first preset voltage; changing a duty cycle of the fourth control signal to conduct a second switch of a primary side circuit and a rectifier side circuit of the second phase circuit; and outputting a single phase voltage to the output terminal.

Description

Multi-phase circuit control method and power conversion device

This case involves an electronic device and control method. Specifically, it involves a multi-phase circuit control method and a power conversion device.

Current electric vehicles require voltages ranging from 400 volts (V) to 800 volts (V), and currents ranging from 1 ampere (A) to 40 amperes (A). Due to the diverse output voltage and current ranges, power converters designed with only a single three-phase resonant circuit cannot achieve the desired gain between the input and output voltages, or the input and output voltages cannot operate within the expected range.

If the three-phase resonant circuit is directly switched to two-phase output or single-phase output, the output voltage and output current will overshoot and undershoot due to the different gain requirements of different phases.

Therefore, the above-mentioned technology still has many shortcomings, and practitioners in this field need to develop other suitable multi-phase circuit control methods and power conversion devices.

One aspect of this disclosure relates to a multi-phase circuit control method. The multi-phase circuit control method is applicable to a multi-phase circuit. The multi-phase circuit is coupled to an input terminal and an output terminal of a power conversion device and is used to convert an input voltage at the input terminal into an output voltage required by the output terminal. The multi-phase circuit includes a first phase circuit and a second phase circuit. The first phase circuit and the second phase circuit each include a primary-side circuit and a rectifier-side circuit. The primary-side circuit and the rectifier-side circuit each include a first switch and a second switch. A multi-phase circuit control method includes: generating a first control signal and a second control signal to a first phase circuit by a controller; generating a third control signal and a fourth control signal to a second phase circuit by the controller; outputting a two-phase voltage to an output terminal by the first phase circuit and the second phase circuit; when the controller detects that the output voltage is lower than a first preset voltage, changing the duty cycle of the third control signal by the controller to close a first switch of a primary-side circuit and a rectifier-side circuit of the second phase circuit; changing the duty cycle of a fourth control signal by the controller to open a second switch of a primary-side circuit and a rectifier-side circuit of the second phase circuit; and outputting a single-phase voltage to an output terminal by the first phase circuit and the second phase circuit.

Another aspect of this disclosure relates to a power conversion device. The power conversion device includes a controller and a multi-phase circuit. The controller is coupled to an input and an output of the power conversion device and is configured to generate a first control signal, a second control signal, a third control signal, and a fourth control signal, respectively. The multi-phase circuit is coupled to the input and output of the power conversion device. The multi-phase circuit includes a first phase circuit and a second phase circuit. The multi-phase circuit is coupled to the input and output of the power conversion device. The first phase circuit is coupled to the controller and is configured to conduct in response to the first and second control signals. The second phase circuit is coupled to the controller and is configured to conduct in response to the third and fourth control signals. The first and second phase circuits together generate a two-phase voltage. When the controller detects that the output voltage at the output terminal is lower than a first preset voltage, the controller changes the duty cycle of the third control signal and the duty cycle of the fourth control signal to control the first phase circuit and the second phase circuit to output a single-phase voltage.

This disclosure provides a control method that enables the multi-phase circuit of a power conversion device to meet different voltage and current ranges. It can also provide three-phase, two-phase, and single-phase voltages on the live wire based on output voltage requirements to meet different gain requirements.

100: Power conversion device

110: Controller

120, 120A, 120B: Multi-phase circuit

111: Sensing circuit

112: Control circuit

113: Signal generation circuit

T1~T12: Switch

S1~S12: Control signal

P1~P3: Primary side circuit

R1~R3: Rectifier side circuit

Vbus: bus terminal voltage

Vo: output voltage

Io: output current

Cbus,Co:Capacitor

Cr, Cr1~Cr3: Resonant capacitor

Lr, Lr1~Lr3: Resonant inductance

LM, LM1~LM3: Magnetizing Inductors

TS, TS1~TS3: Transformer

Ls1~Ls3: Rectifier-side inductors

Cs1~Cs3: Capacitors

H: High level

L: Low level

I1~I5: Stages

I21~I23, I41~I43: Sub-stages

The contents of the present invention can be better understood by referring to the embodiments in the following paragraphs and the following figures: FIG1 is a circuit block diagram of a power conversion device according to some embodiments of the present invention; FIG2 is a circuit architecture diagram of a controller and a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG3 is a step diagram of a multi-phase circuit control method according to some embodiments of the present invention; FIG4 is a control signal timing diagram of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG5 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG6 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG7 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG8 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG9 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG10 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG11 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG12 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG13 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG14 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG15 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG16 is a timing diagram of a control signal of a multi-phase circuit of a power conversion device according to some embodiments of the present invention; FIG17 is a timing diagram of a control signal of a multi-phase circuit Figure 6 is a schematic diagram of a controller and a multiphase circuit of a power conversion device according to some embodiments of the present invention; Figure 7 is a timing diagram of control signals of a multiphase circuit of a power conversion device according to some embodiments of the present invention; Figure 8 is a schematic diagram of a multiphase circuit of a power conversion device according to some embodiments of the present invention; and Figure 9 is a schematic diagram of a multiphase circuit of a power conversion device according to some embodiments of the present invention.

The following diagrams and detailed descriptions clearly illustrate the spirit of this invention. After understanding the embodiments of this invention, anyone with ordinary skill in the art will be able to make changes and modifications based on the techniques taught in this invention without departing from the spirit and scope of this invention.

FIG1 is a schematic circuit block diagram of a power conversion device 100 according to some embodiments of the present invention. The power conversion device 100 includes a controller 110 and a multi-phase circuit 120.

In some embodiments, controller 110 can be implemented purely by hardware and does not rely on software to perform its functions. For example, controller 110 can monitor the input and output voltages of polyphase circuit 120 to generate control signals for various switches (not shown) in polyphase circuit 120. In some embodiments where controller 110 is implemented purely by hardware, controller 110 can be implemented as an application-specific integrated circuit (ASIC).

The controller 110 may include, but is not limited to, a single processor and an integration of multiple microprocessors, such as a central processing unit (CPU), a digital signal processor (DSP), or a graphics processing unit (GPU).

In some embodiments, under the control of controller 110, multi-phase circuit 120 can function as a voltage/power converter to convert input voltage into output voltages of varying specifications, used to drive or power an electrical load (e.g., an electric vehicle, motor, battery, processor, etc., not shown). In some embodiments, multi-phase circuit 120 can be implemented as a bidirectional isolated dual active bridge (DAB) circuit, a three-phase LLC resonant circuit, or other similar multi-phase conversion circuits. Multi-phase circuit 120 utilizes multiple phases to provide output power. By distributing power across multiple phases, it can provide higher power output and greater efficiency. The multi-phase circuit 120 utilizes its resonant characteristics to extend the output voltage range compared to conventional DC/DC converter circuits and reduce DC/DC conversion losses.

Figure 2 is a schematic diagram illustrating the circuit architecture of the controller 110 and polyphase circuit 120A of the power conversion device 100 shown in Figure 1, according to some embodiments of the present invention. In some embodiments, the polyphase circuit 120A is implemented as a DAB circuit (or a two-phase circuit). The controller 110 and polyphase circuit 120A are coupled to the input terminal (i.e., capacitor Cbus, or bus terminal) and the output terminal (i.e., capacitor Co, or between the live and ground wires of the power grid) of the power conversion device 100.

In some embodiments, the controller 110 includes a sensing circuit 111, a control circuit 112, and a signal generation circuit 113. The sensing circuit 111 is used to detect the bus voltage Vbus at the input end, the output voltage Vo and output current Io at the output end, and generate feedback signals to the control circuit 112. The control circuit 112 is used to generate corresponding instructions based on the feedback signals, controlling the signal generation circuit 113 to generate corresponding control signals S1-S8 to the multi-phase circuit 120A. The signal generation circuit 113 is used to generate the control signals S1-S8 to control the multi-phase circuit 120A. In some embodiments, the control signals S1-S8 are pulse-width modulation (PWM) signals.

In some embodiments, the multi-phase circuit 120A includes a first phase circuit, a second phase circuit, a resonant capacitor Cr, a resonant inductor Lr, a magnetizing inductor LM, and a transformer TS. The first phase circuit includes a primary-side circuit P1 and a rectifier-side circuit R1. The second phase circuit includes a primary-side circuit P2 and a rectifier-side circuit R2. Primary-side circuits P1 and P2 are full-bridge circuits. Rectifier-side circuits R1 and R2 are full-bridge circuits.

The multiphase circuit 120A is essentially composed of four structures: the primary side, the resonant side, the transformer side, and the rectifier side. The primary side comprises the aforementioned primary circuits P1 and P2. The primary side converts the DC voltage (i.e., the bus voltage Vbus) into a high-frequency square wave for input to the resonant side. The resonant side comprises the resonant tank formed by the resonant capacitor Cr, the resonant inductor Lr, and the magnetizing inductor LM. The resonant side eliminates the harmonics of the primary side's high-frequency square wave and outputs a sinusoidal wave.

Next, the transformer side is the aforementioned transformer TS. Its function is to output a sine wave to the rectifier side, where it can be stepped up or down as needed. The rectifier side comprises rectifier circuits R1 and R2. The rectifier side converts the sine wave into a stable DC voltage (i.e., the output voltage Vo). The above describes the operation of polyphase circuit 120A and the output of various polyphase voltages.

In some embodiments, the primary-side circuit P1 includes a switch T1 and a switch T2. The primary-side circuit P2 includes a switch T3 and a switch T4. The rectifier-side circuit R1 includes a switch T5 and a switch T6. The rectifier-side circuit R2 includes a switch T7 and a switch T8. Starting from the top and right of the components in the diagram as the first end, switches T1 through T8 each include a first end, a second end, and a control end. The control ends of switches T1 through T8 are alternately turned on in response to the levels of control signals S1 through S8, respectively. The second end of switch T1 and the first end of switch T2 are coupled to the second end of the resonant capacitor Cr. The second end of switch T3 and the first end of switch T4 are coupled to the second end of the magnetizing inductor LM and the fourth end of the transformer TS. The first terminal of the magnetizing inductor LM is coupled to the first terminal of the resonant inductor Lr and the third terminal of the transformer TS. The second terminal of the resonant inductor Lr is coupled to the first terminal of the resonant capacitor Cr. The second terminal of the switch T5 and the first terminal of the switch T6 are coupled to the first terminal of the transformer TS. The second terminal of the switch T7 and the first terminal of the switch T8 are coupled to the second terminal of the transformer TS.

In some embodiments, switches T1 to T8 can be implemented as P-type Metal-Oxide-Semiconductor Field-Effect Transistors (PMOS) or N-type Metal-Oxide-Semiconductor Field-Effect Transistors (NMOS), respectively, depending on actual needs.

To facilitate understanding of the operation of the polyphase circuit 120A of the present invention, please refer to Figures 3 and 4 together. Figure 3 is a schematic diagram illustrating the steps of a polyphase circuit control method 200 according to some embodiments of the present invention. Figure 4 is a timing diagram illustrating control signals of the polyphase circuit 120A of the power conversion device 100 according to some embodiments of the present invention. Figure 5 is a schematic diagram illustrating the circuit status of the polyphase circuit 120A of the power conversion device 100 according to some embodiments of the present invention. The polyphase circuit control method 200 includes steps 210 to 260. The polyphase circuit control method 200 can be executed by the power conversion device 100 of Figure 2.

In step 210, referring to Figures 2 through 4, the signal generation circuit 113 of the controller 110 generates control signals S1 and S2, respectively, to the primary-side circuit P1 of the first phase circuit, and generates control signals S5 and S6, respectively, to the rectifier-side circuit R1 of the first phase circuit. Control signal S1 is essentially the same as control signal S5. Control signal S2 is essentially the same as control signal S6. Control signals S1 and S2 are inversely proportional to each other. The subsequent discussion will primarily focus on control signals S1 and S2. In other words, the subsequent discussion will primarily focus on the primary-side operations. The rectifier-side operations are synchronized with the primary-side operations and will not be further discussed in the following paragraphs.

In step 220, referring to Figures 2 through 4, the controller 110's signal generation circuit 113 generates control signals S3 and S4, respectively, to the primary-side circuit P2 of the second-phase circuit, and generates control signals S7 and S8, respectively, to the rectifier-side circuit R2 of the second-phase circuit. Control signal S3 is essentially the same as control signal S7. Control signal S4 is essentially the same as control signal S8. Control signals S3 and S4 are inversely proportional to each other. The subsequent discussion will primarily focus on control signals S3 and S4. In other words, the subsequent discussion will primarily focus on the primary-side operations. The rectifier-side operations are synchronized with the primary-side operations and will not be detailed in the following paragraphs.

In step 230, referring to Figures 2 through 4, switches T1 and T2 of the primary-side circuit P1 of the first phase circuit are alternately turned on in phase I1 according to control signals S1 and S2, respectively. Simultaneously, switches T3 and T4 of the primary-side circuit P2 of the second phase circuit are alternately turned on according to control signals S3 and S4, respectively. Primary-side circuits P1 and P2 convert the DC voltage (i.e., the bus voltage Vbus) into a high-frequency square wave. Subsequently, a stable two-phase voltage is output to the output terminal (i.e., capacitor Co) through conversion on the resonant side, the transformer side, and the rectifier side, respectively. The detailed operation has been described in the previous paragraph and will not be repeated here. In some embodiments, the bi-phase voltage ranges from 250V to 400V.

Current electric vehicles require voltages ranging from 400 volts (V) to 800 volts (V), and currents ranging from 1 ampere (A) to 40 amperes (A). Due to the need for multiple output voltage and current ranges, for example, the original three-phase voltage and current requirements were 800 V and 30 amperes (A), but now single-phase voltage and current requirements are 150 V and 10 amperes (A), respectively. Power converters that rely solely on a single three-phase resonant circuit design fail to achieve the expected gain between input and output voltages, or fail to operate within the expected operating range.

Furthermore, if a three-phase resonant circuit is directly switched to two-phase or single-phase output, the output voltage and current will experience overshoot and undershoot due to the different gain requirements of the different phases. Overshoot is defined as a signal exceeding the expected value and is a transient response. Conversely, when the signal falls below the expected value, it is called undershoot.

In step 240, referring to Figures 3 through 5, when the controller 110 detects in stage I1 that the output voltage Vo is lower than a preset voltage (e.g., 250V, which is for illustrative purposes only and is not limited to the present embodiment), the controller 110 activates a soft-switching mechanism to switch the output voltage Vo from a stable two-phase voltage to a stable single-phase voltage. By varying the duty cycle of control signal S3, the controller 110 closes switch T3 in the primary-side circuit P2 and switch T7 in the rectifier-side circuit R2 of the second-phase circuit.

In some embodiments, referring to Figures 4 and 5 , controller 110 gradually reduces the duty cycle of control signal S3 in stage I1 from 50% to 30%, 20%, and 10% in each of the three sub-stages I21 through I23 of stage I2. Finally, in stage I3, controller 110 adjusts the duty cycle of control signal S3 to zero.

In step 250, referring to Figures 3 through 5, and continuing with the description of step 240, when the controller 110 detects in stage I1 that the output voltage Vo is lower than a preset voltage (e.g., 250V, which is for example only and not limited to the present embodiment), the controller 110 changes the duty cycle of the control signal S4 to fully turn on switch T4 of the primary-side circuit P2 and switch T8 of the rectifier-side circuit R2 of the second phase circuit.

In some embodiments, referring to Figures 4 and 5, controller 110 gradually increases the duty cycle of control signal S4 in phase I1 from 50% to 70%, 80%, and 90% (relative to control signal S3) in three sub-phases I21 through I23 of phase I2. Finally, in phase I3, controller 110 adjusts the duty cycle of control signal S3 to 100%.

In step 260, referring to Figures 2 through 4, switches T1 and T2 on the primary side of the first-phase circuit P1 are alternately turned on. Simultaneously, switch T3 on the primary side of the second-phase circuit P2 is closed in response to control signal S3, and switch T4 is turned on in response to control signal S4. A stable single-phase voltage is output to the output terminal (i.e., capacitor Co) via the first-phase circuit and the second-phase circuit. The detailed operation is similar to that of step 230 and is not further described here.

In some embodiments, if the output voltage Vo exceeds a preset voltage (e.g., 250V, which is for example only and not limited to the present embodiment), the controller 110 changes the duty cycle of the control signal S3 and the duty cycle of the control signal S4 (equivalent to a reverse transition from phase I3 to phase I1), thereby switching the output of the first and second phase circuits from a stable single-phase voltage to a stable two-phase voltage. The phase difference between each phase is 180°.

Through the soft switching mechanism of the multi-phase circuit control method 200, the multi-phase circuit 120A can output a dual-phase voltage and a single-phase voltage that meet the expected gain, while preventing overshoot and undershoot in the output voltage Vo and output current Io.

Figure 6 is a schematic diagram of the controller 110 and polyphase circuit 120B of the power conversion device 100 according to some embodiments of the present invention. In some embodiments, the polyphase circuit 120B is implemented as a three-phase circuit. The controller 110 and polyphase circuit 120B are coupled to the input terminal (i.e., capacitor Cbus, or bus terminal) and the output terminal (i.e., capacitor Co, or between the live and ground wires of the power grid) of the power conversion device 100. The internal structure and operation of the controller 110 in Figure 6 are essentially the same as the internal structure of the controller 110 in Figure 2 and are not described in detail here. It should be noted that the original two-phase circuit design has been expanded to a three-phase circuit design, and the controller 110 is used to generate corresponding control signals S1-S12 to the polyphase circuit 120B. In some embodiments, the control signals S1-S12 are pulse-width modulation (PWM) signals.

In some embodiments, the multi-phase circuit 120B includes a first phase circuit, a second phase circuit, a third phase circuit, resonant capacitors Cr1-Cr3, resonant inductors Lr1-Lr3, magnetizing inductors LM1-LM3, and transformers TS1-TS3. The first phase circuit includes a primary-side circuit P1 and a rectifier-side circuit R1. The second phase circuit includes a primary-side circuit P2 and a rectifier-side circuit R2. The third phase circuit includes a primary-side circuit P3 and a rectifier-side circuit R3. Primary-side circuits P1, P2, and P3 are half-bridge circuits. Rectifier-side circuits R1, R2, and R3 are half-bridge circuits.

Like multi-phase circuit 120A in Figure 2, multi-phase circuit 120B essentially consists of four components: a primary side, a resonant side, a transformer side, and a rectifier side. The primary side comprises the aforementioned primary circuits P1, P2, and P3, and is used to convert the DC voltage (i.e., the bus voltage Vbus) into a high-frequency square wave for input to the resonant side. The resonant side comprises the aforementioned resonant capacitors Cr1-Cr3, resonant inductors Lr1-Lr3, and magnetizing inductors LM1-LM3, which are used to eliminate the harmonics of the primary-side high-frequency square wave and output a sinusoidal sine wave.

The transformer side, comprising transformers TS1-TS3, outputs a sine wave to the rectifier side, where it performs step-up and step-down operations based on actual needs. The rectifier side, comprising rectifier circuits R1, R2, and R3, converts the sine wave into a stable DC voltage (i.e., output voltage Vo). The above describes the operation of polyphase circuit 120B and its output of various polyphase voltages.

In some embodiments, the primary-side circuit P1 includes switches T1 and T2. The primary-side circuit P2 includes switches T3 and T4. The primary-side circuit P3 includes switches T5 and T6. The rectifier-side circuit R1 includes switches T7 and T8. The rectifier-side circuit R2 includes switches T9 and T10. The rectifier-side circuit R3 includes switches T11 and T12.

In some embodiments, switches T1 to T12 can be implemented as P-type Metal-Oxide-Semiconductor Field-Effect Transistors (PMOS) or N-type Metal-Oxide-Semiconductor Field-Effect Transistors (NMOS) according to actual needs.

Compared to the multi-phase circuit 120A in Figure 2, the first difference between multi-phase circuit 120B and multi-phase circuit 120A is the addition of a third phase. The second difference is that multi-phase circuit 120B includes three sets of resonant tanks (i.e., resonant capacitors Cr1-Cr3, resonant inductors Lr1-Lr3, and magnetizing inductors LM1-LM3), as well as rectifier-side inductors Ls1-Ls3 and capacitors Cs1-Cs3. The circuit structure of multi-phase circuit 120B includes three sets of resonant circuits. Each resonant circuit essentially consists of a pair of half-bridge circuits on the primary and rectifier sides, paired with a set of resonant tanks.

FIG7 is a control signal timing diagram of the multi-phase circuit 120B of the power conversion device 100 according to some embodiments of the present invention. In some embodiments, referring to FIG6 and FIG7 , switches T1 and T2 of the primary-side circuit P1 of the first phase circuit are alternately turned on in phase I1 according to control signals S1 and S2, respectively. Simultaneously, switches T3 and T4 of the primary-side circuit P2 of the second phase circuit are alternately turned on according to control signals S3 and S4, respectively. Switches T5 and T6 of the primary-side circuit P3 of the third phase circuit are alternately turned on according to control signals S5 and S6, respectively. Primary circuits P1, P2, and P3 convert the DC voltage (i.e., the bus voltage Vbus) into a high-frequency square wave. Subsequently, through conversion at the resonant, transformer, and rectifier sides, a stable three-phase voltage is output to the output terminal (i.e., capacitor Co). In some embodiments, the three-phase voltage ranges from 400V to 800V, or above. The phase difference between each phase of the three-phase voltage is 120°.

FIG8 is a schematic diagram illustrating the circuit state of a multi-phase circuit 120B of a power conversion device 100 according to some embodiments of the present invention. In some embodiments, referring to FIG7 and FIG8 , when the controller 110 detects that the output voltage Vo is lower than a preset voltage (e.g., 400V, which is merely an example and not limited to the present embodiments) in phase I1, the controller 110 reduces the duty cycle of the control signal S5 and the duty cycle of the control signal S6 to 30% and 10%, respectively, in sub-phases I21 and I22 of phase I2. Finally, in phase I3, the controller 110 adjusts the duty cycle of control signal S5 and the duty cycle of control signal S6 to zero, shutting down the primary-side circuit P3 and the rectifier-side circuit R3 of the third-phase circuit.

At the same time, the controller 110 gradually increases the phase difference between control signals S1 and S3 from 120° in phase I1 through sub-phases I21 and I22 of phase I2. Finally, in phase I3, the phase difference between control signals S1 and S3 is increased to 180°. Similarly, the controller 110 gradually increases the phase difference between control signals S2 and S4 from 120° in phase I1 through sub-phases I21 and I22 of phase I2. Finally, in phase I3, the phase difference between control signals S1 and S3 is increased to 180°. Finally, the power conversion device 100 outputs a stable two-phase voltage to the output end (i.e., capacitor Co) through conversion on the primary side, resonant side, transformer side, and rectifier side. The phase difference between each phase of the two-phase voltage is 180°.

Figure 9 is a schematic diagram illustrating the circuit state of the multi-phase circuit 120B of the power conversion device 100 according to some embodiments of the present invention. In some embodiments, referring to Figures 7 and 9, when the controller 110 detects in stage I1 that the output voltage Vo further falls below a preset voltage (e.g., 250V, which is for illustrative purposes only and is not limited to the present embodiments), the controller 110 gradually reduces the duty cycle of the control signal S3 in stage I3 from 50% to 30%, 20%, and 10% in each of the three sub-stages I41 through I43 of stage I4. Finally, in stage I5, the controller 110 adjusts the duty cycle of the control signal S3 to zero.

Simultaneously, controller 110 gradually increases the duty cycle of control signal S4 in phase I3 from 50% to 70%, 80%, and 90% (relative to control signal S3) in each of phase I4's three sub-phases, I41 through I43. Finally, in phase I5, controller 110 adjusts the duty cycle of control signal S4 to 100%.

Finally, the power conversion device 100 outputs a stable single-phase voltage to the output end (i.e., capacitor Co) through conversion on the primary side, resonant side, transformer side, and rectifier side.

In some embodiments, if the output voltage Vo is higher than a preset voltage (e.g., 250V, which is for example only and not limited to the present embodiment), the controller 110 changes the duty cycle of the control signal S3 and the duty cycle of the control signal S4 (equivalent to a reverse transition from phase I5 to phase I3), thereby switching the output of the first and second phase circuits from a stable single-phase voltage to a stable two-phase voltage.

In some embodiments, if the output voltage Vo exceeds a preset voltage (e.g., 400V, which is for example only and not limited to the present embodiment), the controller 110 changes the duty cycle of control signal S5 and the duty cycle of control signal S6, and changes the phase of control signal S3 and the phase of control signal S4 (equivalent to a reverse transition from phase I3 to phase I1). This switches the output of a stable two-phase voltage to a stable three-phase voltage via the first, second, and third phase circuits.

Based on the aforementioned embodiments, this invention provides a multi-phase circuit control method design that enables the multi-phase circuit of a power conversion device to meet different voltage and current ranges. Furthermore, the live line can provide multi-phase voltages (e.g., three-phase voltage, two-phase voltage, and single-phase voltage) based on output voltage requirements to meet different gain requirements.

Although this application discloses detailed embodiments above, it does not exclude other feasible implementations. Therefore, the scope of protection of this application shall be determined by the scope of the attached patent application and shall not be limited by the aforementioned embodiments.

200: Method 210-260: Steps

Claims (15)

A multi-phase circuit control method is applicable to a multi-phase circuit coupled to an input terminal and an output terminal of a power conversion device and configured to convert an input voltage at the input terminal into an output voltage required by the output terminal. The multi-phase circuit includes a first phase circuit and a second phase circuit, each of which includes a primary-side circuit and a rectifier-side circuit, wherein each of the primary-side circuit and the rectifier-side circuit includes a first switch and a second switch. The multi-phase circuit control method comprises: Genertizing a first control signal and a second control signal to the first phase circuit by a controller; Genertizing a third control signal and a fourth control signal to the second phase circuit by the controller; A two-phase voltage is output to the output terminal via the first-phase circuit and the second-phase circuit. When the controller detects that the output voltage is lower than a first preset voltage, the controller changes a duty cycle of the third control signal to close the primary-side circuit and the first switch of the rectifier-side circuit of the second-phase circuit. The controller changes a duty cycle of the fourth control signal to open the primary-side circuit and the second switch of the rectifier-side circuit of the second-phase circuit. A single-phase voltage is output to the output terminal via the first-phase circuit and the second-phase circuit. The multi-phase circuit control method of claim 1, wherein the step of causing the controller to change the duty cycle of the third control signal to close the primary-side circuit and the first switch of the rectifier-side circuit of the second phase circuit comprises: The controller gradually reduces the duty cycle of the third control signal during all switching phases; The step of causing the controller to change the duty cycle of the fourth control signal to open the primary-side circuit and the second switch of the rectifier-side circuit of the second phase circuit comprises: The controller gradually increases the duty cycle of the fourth control signal during the switching phase. The multi-phase circuit control method of claim 1, wherein the multi-phase circuit further includes a third-phase circuit, the third-phase circuit including a primary-side circuit and a rectifier-side circuit, wherein the primary-side circuit and the rectifier-side circuit of the third-phase circuit each include a first switch and a second switch, the multi-phase circuit control method further comprising: generating a fifth control signal by the controller to the primary-side circuit and the first switch of the rectifier-side circuit of the third-phase circuit; generating a sixth control signal by the controller and the primary-side circuit and the second switch of the rectifier-side circuit of the third-phase circuit; and outputting a three-phase voltage to the output terminal via the first-phase circuit, the second-phase circuit, and the third-phase circuit. The multi-phase circuit control method of claim 3 further comprises: When the controller detects that the output voltage is lower than a second preset voltage, the controller changes a duty cycle of the fifth control signal and a duty cycle of the sixth control signal to shut down the third phase circuit; The controller changes a phase of the third control signal and a phase of the fourth control signal to adjust a drive mode of the second phase circuit; and Outputting the two-phase voltage to the output terminal via the first phase circuit and the second phase circuit. The multi-phase circuit control method of claim 4, wherein the step of, by the controller, changing the duty cycle of the fifth control signal and the duty cycle of the sixth control signal, respectively, to shut down the third phase circuit comprises: gradually reducing the duty cycle of the fifth control signal by the controller during all switching phases; and gradually reducing the duty cycle of the sixth control signal by the controller during the switching phase. The multi-phase circuit control method of claim 4, wherein the step of adjusting the drive mode of the second phase circuit by changing the phase of the third control signal and the phase of the fourth control signal by the controller comprises: gradually increasing the phase difference between the first control signal and the third control signal by the controller during a switching phase; and gradually increasing the phase difference between the second control signal and the fourth control signal by the controller during the switching phase. The multi-phase circuit control method of claim 4 further comprises: When the controller detects that the output voltage is lower than the first preset voltage, the controller changes the duty cycle of the third control signal and the duty cycle of the fourth control signal; and outputting the single-phase voltage to the output terminal via the first-phase circuit and the second-phase circuit. The multi-phase circuit control method as described in claim 7, wherein the first preset voltage is lower than the second preset voltage. The multi-phase circuit control method of claim 7, wherein the step of, by the controller, changing the duty cycle of the third control signal and the duty cycle of the fourth control signal comprises: gradually reducing, by the controller, the duty cycle of the third control signal during all switching phases; and gradually increasing, by the controller, the duty cycle of the fourth control signal during the switching phase. A power conversion device comprises: A controller coupled to an input terminal and an output terminal of the power conversion device and configured to generate a first control signal, a second control signal, a third control signal, and a fourth control signal, respectively; and A multi-phase circuit coupled to the input terminal and the output terminal of the power conversion device and comprising: A first-phase circuit coupled to the controller and configured to conduct in response to the first and second control signals; and A second-phase circuit coupled to the controller and configured to conduct in response to the third and fourth control signals, wherein the first-phase circuit and the second-phase circuit jointly generate a two-phase voltage. When the controller detects that an output voltage at the output terminal is lower than a first preset voltage, the controller is configured to change the duty cycle of the third control signal and the duty cycle of the fourth control signal to control the first phase circuit and the second phase circuit to output a single-phase voltage. The power conversion device of claim 10, wherein the controller is further configured to generate a fifth control signal and a sixth control signal, and wherein the multi-phase circuit further comprises: A third-phase circuit coupled to the controller and configured to conduct in response to the fifth control signal and the sixth control signal, wherein the third-phase circuit, the first-phase circuit, and the second-phase circuit jointly generate a three-phase voltage. As described in claim 11, the power conversion device, wherein when the controller detects that the output voltage is lower than a second preset voltage, the controller is further used to change the duty cycle of the fifth control signal and the duty cycle of the sixth control signal to close the third phase circuit, wherein the controller is further used to change the phase of the third control signal and the phase of the fourth control signal to control the first phase circuit and the second phase circuit to output the two-phase voltage. The power conversion device as described in claim 12, wherein the duty cycle of the fifth control signal and the duty cycle of the sixth control signal are gradually changed to zero in all switching phases. As described in claim 12, the power conversion device, wherein when the controller detects that the output voltage is lower than the first preset voltage, the controller is further used to change the duty cycle of the third control signal and the duty cycle of the fourth control signal to control the first phase circuit and the second phase circuit to output the single-phase voltage. The power conversion device as described in claim 14, wherein the duty cycle of the third control signal and the duty cycle of the fourth control signal are gradually changed to be different in all switching phases.