Transduction topological structure based on MOSFET and commutation control method of AC power supply

Abstract

The invention provides a transduction topological structure based on MOSFETs and a commutation control method of an alternating current power supply, the transduction topological structure comprises at least four commutation modules, a positive electrode and a negative electrode, the positive electrode and the negative electrode are connected to an X phase and a Y phase of the alternating current power supply respectively, each commutation module comprises at least two MOSFETs, one end of one MOSFET is connected with the alternating current power supply, the other end of the MOSFET is connected with one end of the other MOSFET, and the other end of the other MOSFET is connected with the alternating current power supply. And the other end of the other MOSFET is output, and the two MOSFETs are switched on and switched off at the same time. According to the transduction topological structure, the MOSFET devices are used for performing commutation control on medium-high frequency voltage signals, switching among multiple paths of voltage signals can be realized, and semiconductor devices required by the circuit are small in package, low in cost and wide in selectable range.

Description

Technical Field

[0001] The present invention generally relates to the field of power electronics technology, and particularly relates to a transducer topology based on MOSFET and a commutation control method for an AC power supply, which are applied to the design of a power electronics transducer circuit. Background Art

[0002] In terms of voltage signal control, the requirements include the rapid switching of high-power DC signals. For this type of control circuit, MOSFETs, gallium nitride transistors, or silicon carbide transistors can be selected to implement it. A typical circuit is a half-bridge (full-bridge) drive circuit; the rapid switching of low-frequency high-power signals. For this type of control circuit, thyristors, relays, or switches can be selected to implement it. Typical circuits are thyristor control circuits and relay control circuits; the rapid switching of medium- and high-frequency high-power signals. For this type of control circuit, solid-state relays can be selected. However, due to their large forward voltage drop, high heat generation and power consumption during conduction, and the large package volume of high-power solid-state relays, which is not conducive to the high integration of printed circuit boards, the above circuits cannot be used stably for a long time for the rapid switching of medium- and high-frequency high-power signals.

[0003] The content in the background art section is only the technology known to the inventor and does not of course represent the prior art in this field. Summary of the Invention

[0004] In view of one or more of the problems existing in the prior art, the present invention provides a transducer topology based on MOSFET and a commutation control method for an AC power supply, which can realize the reliable and stable switching of an AC power supply, such as a medium- and high-frequency voltage signal, and the semiconductor devices required by the circuit have a small package, low cost, and a wide selection range.

[0005] On the one hand, a commutation control method for an AC power supply provided by an embodiment of the present invention is applied to a transducer topology based on MOSFET. The transducer topology includes a first commutation module, a second commutation module, a third commutation module, and a fourth commutation module. The first end of the first commutation module and the first end of the third commutation module are adapted to be connected to the AC power supply. The second end of the first commutation module and the second end of the third commutation module serve as the X-phase output terminal. The first end of the second commutation module and the first end of the fourth commutation module are adapted to be connected to the AC power supply. The second end of the second commutation module and the second end of the fourth commutation module serve as the Y-phase output terminal. The first commutation module, the second commutation module, the third commutation module, and the fourth commutation module respectively include a bootstrap unit and two back-to-back MOSFETs. The bootstrap unit is adapted to bootstrap the control terminal voltage of the corresponding commutation module so that the turn-on voltages of the two MOSFETs always remain at a set value. The method includes:

[0006] Control the first commutation module, the second commutation module, the third commutation module, and the fourth commutation module respectively, so that

[0007] when the first commutation module and the third commutation module are turned on, the second commutation module and the fourth commutation module are turned off;

[0008] when the first commutation module and the third commutation module are turned off, the second commutation module and the fourth commutation module are turned on;

[0009] Among them, when the first commutation module and the third commutation module are turned on, the bootstrap units of the first commutation module and the third commutation module work to output the X-phase output terminal to the AC power supply; when the second commutation module and the fourth commutation module are turned on, the bootstrap units of the second commutation module and the fourth commutation module work to output the Y-phase output terminal to the AC power supply.

[0010] Optionally, the transducer topology further includes a first controllable switch module and a second controllable switch module. The first controllable switch module and the second controllable switch module each include a power resistor. The first controllable switch module is arranged corresponding to the X-phase output terminal, and the second controllable switch module is arranged corresponding to the Y-phase output terminal. The method further includes: when the X-phase output terminal outputs to the AC power supply, control the first controllable switch module to turn off and control the second controllable switch module to turn on, so that the power resistor in the second controllable switch module is connected between the positive and negative poles of the Y-phase output terminal to limit the Y-phase output terminal; when the Y-phase output terminal outputs to the AC power supply, control the first controllable switch module to turn on and control the second controllable switch module to turn off, so that the power resistor in the first controllable switch module is connected between the positive and negative poles of the X-phase output terminal to limit the X-phase output terminal.

[0011] Optionally, the MOSFET is an NMOS transistor. Among them, the sources of two back-to-back NMOS transistors are connected and then connected to one end of the bootstrap unit, and the gates of the two back-to-back NMOS transistors are connected and then connected to the other end of the bootstrap unit.

[0012] Optionally, the bootstrap unit includes a capacitor. The capacitor is connected between the gate and the source of the two NMOS transistors, and both ends of the capacitor are adapted to be connected to the control terminal voltage of the corresponding commutation module.

[0013] Optionally, a first transient suppression diode is further connected between the second end of the first commutation module and the second end of the third commutation module, and a second transient suppression diode is further connected between the second end of the second commutation module and the second end of the fourth commutation module.

[0014] On the other hand, an embodiment of the present invention further provides a transducer topology based on MOSFETs, which includes a first commutation module, a second commutation module, a third commutation module, and a fourth commutation module. The first ends of the first commutation module and the third commutation module are adapted to be connected to the AC power supply. The second ends of the first commutation module and the third commutation module serve as the X-phase output terminals. The first ends of the second commutation module and the fourth commutation module are adapted to be connected to the AC power supply. The second ends of the second commutation module and the fourth commutation module serve as the Y-phase output terminals. The first commutation module, the second commutation module, the third commutation module, and the fourth commutation module respectively include a bootstrap unit and two back-to-back MOSFETs. The bootstrap unit is adapted to bootstrap the control terminal voltage of the corresponding commutation module so that the turn-on voltages of the two MOSFETs are always maintained at a set value. Among them, when the first commutation module and the third commutation module are conducting, the second commutation module and the fourth commutation module are turned off, and the bootstrap units of the first commutation module and the third commutation module operate to output the X-phase output terminal to the AC power supply; when the first commutation module and the third commutation module are turned off, the second commutation module and the fourth commutation module are conducting, and the bootstrap units of the second commutation module and the fourth commutation module operate to output the Y-phase output terminal to the AC power supply.

[0015] Optionally, the transducer topology further includes a first controllable switch module and a second controllable switch module. The first controllable switch module and the second controllable switch module respectively include a power resistor. The first controllable switch module is disposed corresponding to the X-phase output terminal, and the second controllable switch module is disposed corresponding to the Y-phase output terminal. Among them, when the X-phase output terminal outputs to the AC power supply, the first controllable switch module is turned off, and the second controllable switch module is closed so that the power resistor in the second controllable switch module is connected between the positive and negative poles of the Y-phase output terminal to limit the Y-phase output terminal; when the Y-phase output terminal outputs to the AC power supply, the first controllable switch module is closed, and the second controllable switch module is turned off so that the power resistor in the first controllable switch module is connected between the positive and negative poles of the X-phase output terminal to limit the X-phase output terminal.

[0016] Optionally, the resistance value of the power resistor is less than a preset threshold.

[0017] Optionally, the MOSFET is an NMOS transistor. Among them, the sources of two back-to-back NMOS transistors are connected and then connected to one end of the bootstrap unit, and the gates of the two back-to-back NMOS transistors are connected and then connected to the other end of the bootstrap unit.

[0018] Optionally, the bootstrap unit includes a capacitor. The capacitor is connected between the gates and sources of the two NMOS transistors, and both ends of the capacitor are adapted to access the control terminal voltage of the corresponding commutation module.

[0019] The commutation control method of the AC power supply and the energy conversion topology structure based on MOSFET provided by the embodiments of the present invention can realize that when the first commutation module and the third commutation module are turned on, the second commutation module and the fourth commutation module are turned off by the coordinated control of the first commutation module, the second commutation module, the third commutation module and the fourth commutation module. At this time, the bootstrap units of the first commutation module and the third commutation module work, so that the turn-on voltages of the two MOSFETs in each of these two commutation modules are always maintained at the set value. In this way, the first commutation module and the third commutation module are always maintained in the on state, realizing a stable and reliable output of the AC power supply at the X-phase output terminal; when the first commutation module and the third commutation module are turned off, the second commutation module and the fourth commutation module are turned on. At this time, the bootstrap units of the second commutation module and the fourth commutation module work, so that the turn-on voltages of the two MOSFETs in each of these two commutation modules are always maintained at the set value. In this way, the second commutation module and the fourth commutation module are always maintained in the on state, realizing a stable and reliable output of the AC power supply at the Y-phase output terminal. Therefore, the commutation control method of the AC power supply and the energy conversion topology structure based on MOSFET provided by the embodiments of the present invention, through the use of MOSFET devices arranged back-to-back and the bootstrap following action of the bootstrap unit, ensure that when performing commutation control of an AC power supply such as a medium-high frequency voltage signal, free, reliable and stable switching of the AC power supply output in the X direction and the Y direction can be realized. Not only is the circuit topology simple and reliable, but also the leakage current can be controlled, ensuring effective switching output of the AC power supply between the X phase and the Y phase. In addition, the semiconductor devices required by the circuit have a small package, low cost and a wide selection range. Description of the Drawings

[0020] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation to the present invention. In the drawings:

[0021] Figure 1 is a schematic diagram of the energy conversion topology structure based on MOSFET of the present invention;

[0022] Figure 2It is a schematic diagram of a preferred embodiment of the MOSFET-based transducer topology of the present invention;

[0023] Figure 3a It is a schematic diagram of the amplitude of the input voltage waveform;

[0024] Figure 3b It is a schematic diagram of the frequency of the input voltage waveform;

[0025] Figure 4a It is a schematic diagram of the X-phase voltage output waveform;

[0026] Figure 4b It is a schematic diagram of the Y-phase voltage output waveform;

[0027] Figure 4c It is a schematic diagram of the X-phase voltage output frequency and the peak-to-peak current;

[0028] Figure 4d It is a schematic diagram of the Y-phase voltage output frequency and the peak-to-peak current. Detailed implementation manners

[0029] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0030] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0031] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0032] Figure 1 It is a schematic diagram of the MOSFET-based transducer topology described in the present invention, as Figure 1As shown, the MOSFET-based transducer topology structure includes four commutation modules H1 to H4 and two relay control modules J1 to J2, where:

[0033] The four commutation modules H1 to H4 are respectively connected to the positive and negative poles of the X phase and Y phase of the AC signal source. Each commutation module includes two MOSFETs. The sources of the two MOSFETs are connected. The drain of one MOSFET is connected to the AC power supply, and the drain of the other MOSFET is used as the AC output. A capacitor is connected between the positive and negative poles of the external circuit that supplies power to the gates of the two MOSFETs.

[0034] The two relay control modules are respectively connected to the X-phase output terminal and Y-phase output terminal of the commutation module. The relay control module includes a relay. A power resistor is arranged between the relay and the X-phase positive output terminal or Y-phase positive output terminal of the commutation module. The positive enabling terminal of the relay is connected to an external voltage through a current-limiting resistor, and the negative enabling terminal of the relay is connected to an external voltage through an NMOS transistor.

[0035] As Figure 1 shown, the four commutation modules are respectively the first commutation module H1, the second commutation module H2, the third commutation module H3, and the fourth commutation module H4, and the two relay control modules are respectively the first relay control module J1 and the second relay control module J2, where:

[0036] The first commutation module H1 includes the first field-effect transistor Q1, the second field-effect transistor Q2, and the first capacitor C1. The sources of the first field-effect transistor Q1 and the second field-effect transistor Q2 are connected, and the source voltage is denoted as U1. The drain of the second field-effect transistor Q2 is connected to the positive pole of the X phase of the AC signal source. The drain of the first field-effect transistor Q1 is used as the output AC-OUT-X+ of the positive pole of the X phase of the AC signal source. The voltages of the gates of the first field-effect transistor Q1 and the second field-effect transistor Q2 are denoted as U2. The gates are connected to the external circuit, and a first capacitor C1 is arranged between the voltage DC-X+A obtained from the positive pole of the external circuit and the voltage DC-X-A obtained from the negative pole of the external circuit for the gates.

[0037] The third commutation module H3 includes the fifth field-effect transistor Q5, the sixth field-effect transistor Q6, and the third capacitor C3. The sources of the fifth field-effect transistor Q5 and the sixth field-effect transistor Q6 are connected, and the source voltage is denoted as U3. The drain of the sixth field-effect transistor Q6 is connected to the negative pole of the X phase of the AC signal source. The drain of the fifth field-effect transistor Q5 is used as the output AC-OUT-X- of the negative pole of the X phase of the AC signal source. The voltages of the gates of the fifth field-effect transistor Q5 and the sixth field-effect transistor Q6 are denoted as U4. The gates are connected to the external circuit, and a third capacitor C3 is arranged between the voltage DC-X+B obtained from the positive pole of the external circuit and the voltage DC-X-B obtained from the negative pole of the external circuit for the gates.

[0038] The second commutation module H2 includes a third field effect transistor Q3, a fourth field effect transistor Q4 and a second capacitor C2. The sources of the third field effect transistor Q3 and the fourth field effect transistor Q4 are connected. The drain of the third field effect transistor Q3 is connected to the positive pole of the Y phase of the AC signal source. The drain of the fourth field effect transistor Q4 serves as the output AC-OUT-Y+ of the positive pole of the Y phase of the AC signal source. The gates of the third field effect transistor Q3 and the fourth field effect transistor Q4 are connected to an external circuit, and a second capacitor C2 is provided between the voltage DC-Y+A obtained from the positive pole of the external circuit and the voltage DC-Y-A obtained from the negative pole of the external circuit at the gates;

[0039] The fourth commutation module H4 includes a seventh field effect transistor Q7, an eighth field effect transistor Q8 and a fourth capacitor C4. The sources of the seventh field effect transistor Q7 and the eighth field effect transistor Q8 are connected. The drain of the seventh field effect transistor Q7 is connected to the negative pole of the Y phase of the AC signal source. The drain of the eighth field effect transistor Q8 serves as the output AC-OUT-Y- of the negative pole of the Y phase of the AC signal source. The gates of the seventh field effect transistor Q7 and the eighth field effect transistor Q8 are connected to an external circuit, and a fourth capacitor C4 is provided between the voltage DC-Y+B obtained from the positive pole of the external circuit and the voltage DC-Y-B obtained from the negative pole of the external circuit at the gates;

[0040] The first relay control module J1 includes a relay UJ1. The positive pole and the negative pole of the AC terminal of the relay UJ1 are respectively connected to the output terminal AC-OUT-X+ of the first commutation module Q1 and the output terminal AC-OUT-X- of the third commutation module Q5. A power resistor R1 is provided at the positive pole of the AC terminal connected to the first commutation module. The positive pole of the DC terminal of the relay UJ1 is connected to the external voltage VCC through a current limiting resistor R2. The positive pole of the DC terminal of the relay UJ1 is connected to the collector of the first NPN transistor T1. The base of the first NPN transistor T1 is connected to the external voltage ENX through a current limiting resistor R3;

[0041] The second relay control module J2 includes a relay UJ2. The positive pole and the negative pole of the AC terminal of the relay UJ2 are respectively connected to the output terminal AC-OUT-Y+ of the second commutation module Q4 and the output terminal AC-OUT-Y- of the fourth commutation module Q8. A power resistor R5 is provided at the positive pole of the AC terminal connected to the second commutation module. The positive pole of the DC terminal of the relay UJ2 is connected to the external voltage VCC through a current limiting resistor R4. The positive pole of the DC terminal of the relay UJ2 is connected to the collector of the second NPN transistor T2. The base of the second NPN transistor T2 is connected to the external voltage ENY,

[0042] Among them, the AC signal source serves as the input terminal of the controlled medium and high-frequency voltage signal. When the voltages of DC-X+A, DC-X-A, DC-X+B, and DC-X-B obtained from the external circuit are not lower than the MOSFET turn-on voltage VGS, the field-effect transistors Q1, Q2, Q5, and Q6 are turned on, and the voltages between U1 and U2 and the voltage VGS between U3 and U4 are immediately bootstrapped to the input voltage. However, the voltage difference between the two ends of DC-X+A, DC-X-A, DC-X+B, and DC-X-B always remains VGS unchanged, enabling the input voltage signal to be output to the AC-OUT-X+ and AC-OUT-X- terminals. At this time, Q3, Q4, Q7, and Q8 are in the off state. Affected by the turn-off of Q3 and Q7, the positive half-axis voltage cannot be transmitted backward. Although the negative half-axis voltage can conduct backward through the body diodes of Q3 and Q7, it is also affected by the turn-off of Q4 and Q8 and cannot be transmitted backward. However, due to the existence of the MOSFET junction capacitance COSS, there is a saturation drain current IDSS. Moreover, as the frequency of the input signal increases, the capacitance impedance decreases, and the drain current becomes larger. Therefore, even if Q3, Q4, Q7, and Q8 remain off, when the positive and negative half-axis voltages alternately operate on the four MOSFETs, there are still drain currents on the MOSFETs outputting to the AC-OUT-Y+ and AC-OUT-Y- terminals respectively. Therefore, it is necessary to add a second relay control module J2 to keep ENY at a high level and ENX at a low level, enabling the control relay UJ2, and connecting the "dummy load" R5 to both ends of AC-OUT-Y+ and AC-OUT-Y-. This allows the drain current to pass through R5, and the voltages at the AC-OUT-Y+ and AC-OUT-Y- terminals are the voltages across R5. According to Ohm's law U = IR, as long as R is small enough, the voltages at the AC-OUT-Y+ and AC-OUT-Y- terminals can be significantly suppressed. In this process, the voltages on AC-OUT-X+ and AC-OUT-X- can be approximately equal to the input voltage, while the voltages at the AC-OUT-Y+ and AC-OUT-Y- terminals are significantly limited, approaching the "turn-off" effect. Similarly, if Q3, Q4, Q7, and Q8 are kept on and Q1, Q2, Q5, and Q6 are off, and at the same time ENX is kept at a high level and ENY is kept at a low level to enable the control relay UJ1, the "dummy load" R1 is connected to both ends of AC-OUT-X+ and AC-OUT-X-, and the voltages on AC-OUT-Y+ and AC-OUT-Y- can be approximately equal to the input voltage, while the voltages at the AC-OUT-X+ and AC-OUT-X- terminals approach the "turn-off" effect. By operating alternately in this way, the voltage energy exchange in the X and Y directions is realized.

[0043] In addition to adopting a similar DC voltage control method, the MOSFET-based transducer topology structure of the present invention adds a relay control circuit, introduces a "false load", and uses a reasonable gating method to make the input medium and high-frequency high-power voltage signal alternately output at the output end, breaking the traditional idea that MOSFET cannot control medium and high-frequency high-power voltage signals.

[0044] Figure 2 is a schematic diagram of a preferred embodiment of the MOSFET-based transducer topology structure of the present invention, as Figure 2 shown, the MOSFET-based transducer topology structure includes four commutation modules H1 to H4 and two relay control modules J1 and J2. Fuse fuses F1 and F2 are provided at the positive output ends of the first commutation module H1 and the second commutation module H2. A parallel load power resistor R7 and a transient suppression diode D1 are provided between the positive output end AC-OUT-X+ of the first commutation module H1 and the negative output end AC-OUT-X- of the third commutation module H3. A parallel load power resistor R8 and a transient suppression diode D2 are provided between the positive output end of the second commutation module H2 and the negative output end of the fourth commutation module H4. As Figure 3a and 3b shown, an AC signal with a peak-to-peak value of 130V and a frequency of 200KHz enters from the AC signal source terminal. Within 900ms, a 5V voltage is externally input to DC-X+A, DC-X-A, DC-X+B, and DC-X-B. DC-Y+A, DC-Y-A, DC-Y+B, and DC-Y-B are kept floating. A 3.3V high level is externally input to the ENY terminal to close T2, so that R5 is connected to the AC-OUT-Y+ and AC-OUT-Y- terminals. At this time, the oscilloscope pen is clipped to the AC-OUT-X+ and AC-OUT-X- terminals, and an approximate input AC signal can be obtained. And through a current probe, the current on the R7 load can be monitored to be about 1.3A, while the voltages at the AC-OUT-Y+ and AC-OUT-Y- terminals are "switched off". Similarly, in the next 900ms cycle, a 5V voltage is externally input to DC-Y+A, DC-Y-A, DC-Y+B, and DC-Y-B. DC-X+A, DC-X-A, DC-X+B, and DC-X-B are kept floating. A 3.3V high level is externally input to the ENX terminal to close T1, so that the voltages at the AC-OUT-Y+ and AC-OUT-Y- terminals are "switched on", the voltages at the AC-OUT-X+ and AC-OUT-X- terminals are "switched off", and the current on the R8 load is also about 1.3A. As Figures 4a - 4dAs shown, the X-phase and Y-phase output voltages are complementary and alternate with a conversion period of 900 ms, and their amplitudes and frequencies basically remain unchanged. When a medium-high frequency voltage with a peak-to-peak input of 130 V and a frequency of 200 kHz is applied, this circuit can realize the alternating conversion of the X-phase and Y-phase voltages. When a high-power load is connected to the output terminal, the current output capacity can reach about 1.3 A, and it can operate stably for a long time. Figures 3a to 4d These are the results of saving the waveforms obtained by using an oscilloscope (Tektronix DPO2012B) for testing. Different horizontal and vertical scales are set according to different test requirements, which has no impact on the signal itself and is convenient for observing and studying the signal. For example, Figure 3a in [a certain situation], the horizontal scale is 200 ms / div and the vertical scale of Channel 1 is 50 V / div; Figure 3b in [a certain situation], the horizontal scale is 2 μs / div and the vertical scale of Channel 1 is 50 V / div; Figure 4a in [a certain situation], the horizontal scale is 400 ms / div and the vertical scale of Channel 1 is 50 V / div; Figure 4b in [a certain situation], the horizontal scale is 400 ms / div and the vertical scale is 50 V / div; Figure 4c in [a certain situation], the horizontal scale is 2 μs / div, the vertical scale of Channel 1 is 50 V / div, and the vertical scale of Channel 2 is 500 mA / div; Figure 4d in [a certain situation], the horizontal scale is 2 μs / div, the vertical scale of Channel 1 is 50 V / div, and the vertical scale of Channel 2 is 500 mA / div.

[0045] In a specific embodiment of the present invention, F1 and F2 are fast-blow fuses of UN2410-1300FS, with a rated current of 3A and a maximum voltage of 250V, and their function is to protect the output voltage and current of the circuit from exceeding the design limit; R7 and R8 are load power resistors, which are 100Ohm 150W aluminum shell power resistors, and their function is to act as a load to test the load-carrying capacity of the circuit; D1 and D2 are SMBJ400CA avalanche diodes, with a reverse breakdown voltage of 400V, and their function is to improve the electrostatic protection level of the circuit; Q1, Q2, Q3, Q4, Q5, Q6, Q7, and Q8 are N-channel MOSFETs of BSC320N20NS3G. The VDS between the source and drain is 200V, the current that can be tolerated is 36A, the output junction capacitance COSS is at most 180pF, and the maximum drain current IDSS at room temperature is 1nA (condition: VDS = 160V, VGS = 0). It can be known from the basic schematic diagram of the MOSFET that there are junction capacitances between the gate, source, and drain of the MOSFET, which are CGD, CGS, and CDS respectively. In the off state of the MOSFET, VGS = 0, and the gate-source can be regarded as short-circuited. Therefore, the output junction capacitance of the MOSFET is CGD + CDS, that is, COSS. According to the capacitance impedance XC = 1 / jωC, under the condition of a certain frequency, the smaller the capacitance value, the larger its impedance. Therefore, if the COSS value of the selected MOSFET is smaller, its "off" effect is better, and this value is positively correlated with the drain current IDSS; C1, C2, C3, and C4 are ceramic capacitors of GRM219B31H225KE15D, Murata 2.2uF, 50V, 0805 package surface mount capacitors, and their function is to act as bootstrap capacitors to boost the voltage and keep the voltage difference at the control end at 5V all the time; UJ1 and UJ2 are G3VM-201G1 MOSFET relays, with a load voltage VOFF of 200V peak voltage and a continuous current IO of 200mA, and their function is to connect the "dummy load" periodically to control the conversion period; R1 and R5 are surface mount power resistors of 25121WF510JT4E, 51Ohm, 1W surface mount resistors, and their function is to be the "dummy load" of the circuit; R2 and R4 are current-limiting resistors of 0603WAF1001T5E, and their function is to be the current-limiting resistors at the MOSFET control end. Their forward current IF needs to be below 25mA. Preferably, R2 and R4 are 1KOhm, 1 / 8W surface mount resistors, and the forward current IF is 5mA; T1 and T2 are SS8050, NPN-type triodes, and their function is to facilitate the MCU to drive the MOSFET control ends ENX and ENY; R3 and R6 are current-limiting resistors of 0603WAF1001T5E, 1KOhm, 1 / 10W surface mount resistors, and their function is to prevent the base current of SS8050 from being too large.

[0046] The MOSFET-based commutation topology structure of the present invention uses a simple and efficient field effect transistor and a combination of resistor and capacitor components to commutate and control a voltage signal of medium and high frequencies, has a strong current output capacity, and can operate stably for a long time.

[0047] The above gives an embodiment including four commutation modules and two relay control modules, but the present invention is not limited thereto. The positive electrode or / and negative electrode of each phase of the AC signal source may respectively include multiple commutation modules, or may include a multi-channel relay control module, or may include multiple relay control modules, or other switch control modules connected to the output of the commutation module may also be adopted. That is to say, the MOSFET-based commutation topology structure of the present invention may include at least four commutation modules, which are respectively connected to the positive and negative electrodes of the X phase and Y phase of the AC power supply. The commutation module includes at least two MOSFETs. One end of one MOSFET is connected to the AC power supply, and the other end is connected to one end of another MOSFET. The other end of the other MOSFET is the output. The two MOSFETs are turned on and off simultaneously. The MOSFET-based commutation topology structure of the present invention may also include one or more relay control modules for reducing the leakage current of the unconducted commutation module. The relay control module includes a relay and a power resistor. The power resistor is connected between the output end of the unconducted commutation module and the relay, and the magnitude of the leakage current is controlled by the resistance value of the power resistor.

[0048] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A commutation control method for an AC power supply, characterized in that, Applied to a MOSFET-based transducer topology, the transducer topology includes a first commutation module, a second commutation module, a third commutation module, and a fourth commutation module. The first end of the first commutation module and the first end of the third commutation module are adapted to be connected to the AC power supply. The second end of the first commutation module and the second end of the third commutation module serve as the X-phase output terminals. The first end of the second commutation module and the first end of the fourth commutation module are adapted to be connected to the AC power supply. The second end of the second commutation module and the second end of the fourth commutation module serve as the Y-phase output terminals. The first commutation module, the second commutation module, the third commutation module, and the fourth commutation module respectively include a bootstrap unit and two back-to-back MOSFETs. The bootstrap unit is adapted to bootstrap the control terminal voltage of the corresponding commutation module so that the turn-on voltages of the two MOSFETs are always maintained at a set value. The method includes: Controlling the first commutation module, the second commutation module, the third commutation module, and the fourth commutation module respectively, so that When the first commutation module and the third commutation module are conducting, the second commutation module and the fourth commutation module are turned off; When the first commutation module and the third commutation module are turned off, the second commutation module and the fourth commutation module are conducting; Wherein, when the first commutation module and the third commutation module are conducting, the bootstrap units of the first commutation module and the third commutation module operate to output the X-phase output terminal to the AC power supply; when the second commutation module and the fourth commutation module are conducting, the bootstrap units of the second commutation module and the fourth commutation module operate to output the Y-phase output terminal to the AC power supply.

2. The commutation control method of an AC power supply according to claim 1, characterized in that The transducer topology further includes a first controllable switch module and a second controllable switch module. The first controllable switch module and the second controllable switch module respectively include a power resistor. The first controllable switch module is disposed corresponding to the X-phase output terminal, and the second controllable switch module is disposed corresponding to the Y-phase output terminal. The method further includes: When the X-phase output terminal outputs to the AC power supply, controlling the first controllable switch module to turn off and controlling the second controllable switch module to close, so that the power resistor in the second controllable switch module is connected between the positive and negative poles of the Y-phase output terminal to limit the Y-phase output terminal; When the Y-phase output terminal outputs to the AC power supply, controlling the first controllable switch module to close and controlling the second controllable switch module to turn off, so that the power resistor in the first controllable switch module is connected between the positive and negative poles of the X-phase output terminal to limit the X-phase output terminal.

3. The commutation control method of the AC power supply according to claim 1 or 2, characterized in that, The MOSFET is an NMOS transistor. Wherein, the sources of the two back-to-back NMOS transistors are connected and then connected to one end of the bootstrap unit, and the gates of the two back-to-back NMOS transistors are connected and then connected to the other end of the bootstrap unit.

4. The commutation control method of the AC power supply according to claim 3, characterized in that, The bootstrap unit includes a capacitor, the capacitor is connected between the gates and sources of the two NMOS transistors, and both ends of the capacitor are adapted to access the control terminal voltage of the corresponding commutation module.

5. The commutation control method of the AC power supply according to claim 1 or 2, characterized in that, A first transient suppression diode is also connected between the second ends of the first commutation module and the third commutation module, and a second transient suppression diode is also connected between the second ends of the second commutation module and the fourth commutation module.

6. A MOSFET-based transducer topology, characterized in that, It includes a first commutation module, a second commutation module, a third commutation module and a fourth commutation module. The first ends of the first commutation module and the third commutation module are adapted to access the AC power supply. The second ends of the first commutation module and the third commutation module are used as the X-phase output terminals. The first ends of the second commutation module and the fourth commutation module are adapted to access the AC power supply. The second ends of the second commutation module and the fourth commutation module are used as the Y-phase output terminals. The first commutation module, the second commutation module, the third commutation module and the fourth commutation module respectively include a bootstrap unit and two back-to-back MOSFETs. The bootstrap unit is adapted to bootstrap the control terminal voltage of the corresponding commutation module so that the turn-on voltages of the two MOSFETs are always maintained at a set value. Among them, When the first commutation module and the third commutation module are conducting, the second commutation module and the fourth commutation module are turned off, and the bootstrap units of the first commutation module and the third commutation module operate to output the X-phase output terminal to the AC power supply. When the first commutation module and the third commutation module are turned off, the second commutation module and the fourth commutation module are conducting, and the bootstrap units of the second commutation module and the fourth commutation module operate to output the Y-phase output terminal to the AC power supply.

7. The transducer topology according to claim 6, wherein The transducer topology further includes a first controllable switch module and a second controllable switch module. The first controllable switch module and the second controllable switch module respectively include a power resistor. The first controllable switch module is arranged corresponding to the X-phase output terminal, and the second controllable switch module is arranged corresponding to the Y-phase output terminal. Among them, When the X-phase output terminal outputs to the AC power supply, the first controllable switch module is turned off and the second controllable switch module is closed, so that the power resistor in the second controllable switch module is connected between the positive and negative poles of the Y-phase output terminal to limit the Y-phase output terminal. When the Y-phase output terminal outputs to the AC power supply, the first controllable switch module is closed and the second controllable switch module is turned off, so that the power resistor in the first controllable switch module is connected between the positive and negative poles of the X-phase output terminal to limit the X-phase output terminal.

8. The transducer topology according to claim 7, characterized in that, The resistance value of the power resistor is less than a preset threshold.

9. The transducer topology according to any one of claims 6-7, characterized in that, The MOSFET is an NMOS transistor. Among them, the sources of two back-to-back NMOS transistors are connected and then connected to one end of the bootstrap unit, and the gates of the two back-to-back NMOS transistors are connected and then connected to the other end of the bootstrap unit.

10. The transducer topology according to claim 9, wherein The bootstrap unit includes a capacitor. The capacitor is connected between the gate and the source of the two NMOS transistors, and both ends of the capacitor are adapted to access the control terminal voltage of the corresponding commutation module.

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