Isolated three-phase power supply structure and control method

Abstract

The invention discloses an isolated three-phase power supply structure and a control method, and relates to the technical field of electric power engineering, the structure comprises a conversion module, a chopping voltage regulation module, a three-phase bridge and a voltage isolation module which are connected in sequence; the conversion module is used for converting alternating current into direct current; the chopping voltage regulating module is used for regulating the direct current; the three-phase bridge is used for converting the adjusted direct current into three-phase alternating current; and the voltage isolation module is used for electrically isolating the three-phase alternating current and outputting the isolated three-phase alternating current to a load. The three-phase output power supply is isolated through the voltage isolation module, the circuit is protected, the stability is improved, and different alternating currents are generated by controlling the three-phase bridge so as to meet the corresponding three-phase load; and the isolation three-phase power supply structure can be flexibly applied to use scenes with different input currents and output voltages through the conversion module and the conversion voltage regulation module.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power engineering, and in particular to an isolated three-phase power supply structure and a control method. Background Art

[0002] Three-phase power supply is a power transmission and distribution system widely used in industrial and commercial fields. It is favored for its high efficiency, stability and economy. Three-phase power supply generates three sinusoidal voltages with a phase difference of 120 degrees through a rotating magnetic field, and each phase corresponds to a set of coils, forming three independent but interrelated voltage outputs.

[0003] Existing technologies lack flexibility. Non-isolated power supplies have common-mode noise, which is prone to electromagnetic interference. Non-isolated power supplies are more likely to be transmitted to the load end, affecting the signal integrity of the system, leading to measurement errors, communication failures, and performance issues such as the risk of electric shock. This impact is particularly evident for precision instruments and control equipment.

[0004] In the process of implementing the present invention, the inventors found that there are at least the following problems in the prior art:

[0005] Existing non-isolated power supplies have the risk of electromagnetic interference and electric shock, lack flexibility, and easily affect the stability of the control circuit. Summary of the invention

[0006] The purpose of the present invention is to provide an isolated three-phase power supply structure and control method to solve the technical problems in the prior art that the existing non-isolated power supply has electromagnetic interference and electric shock risks, lacks flexibility, and easily affects the stability of the control circuit.

[0007] The various technical effects that can be produced by the preferred technical solutions among the various technical solutions provided by the present invention are described in detail below.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An isolated three-phase power supply structure provided by the present invention comprises: a conversion module, a chopping voltage regulation module, a three-phase bridge and a voltage isolation module connected in sequence;

[0010] The conversion module is used to convert alternating current into direct current;

[0011] The chopper voltage regulation module is used to regulate direct current;

[0012] The three-phase bridge is used to convert the regulated direct current into three-phase alternating current;

[0013] The voltage isolation module is used to electrically isolate the three-phase alternating current and output the isolated three-phase alternating current to the load.

[0014] Optionally, the conversion module includes an AC power supply U1 and a rectifier bridge D1, the third pole of the rectifier bridge D1 is connected to the first pole of the AC power supply U1, the fourth pole of the rectifier bridge D1 is connected to the second pole of the AC voltage, the first pole and the second pole of the rectifier bridge D1 are connected to the chopper voltage regulation module, and the rectifier bridge D1 is used to rectify the AC power output by the AC power supply U1 into DC power.

[0015] Optionally, the chopper voltage regulation module includes a chopper voltage regulation transistor Q1, an inductor L1, a freewheeling diode U2, a capacitor C1, a capacitor C2 and a capacitor C3, wherein the chopper voltage regulation transistor Q1 and the inductor L1 are arranged in series between the first pole of the rectifier bridge D1 and the first pole of the three-phase bridge; the capacitor C1 is connected in series with the capacitor C2, and the first pole of the capacitor C1 is connected between the first pole of the rectifier bridge D1 and the first pole of the chopper voltage regulation transistor Q1, and the second pole of the capacitor C2 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge; the first pole of the freewheeling diode U2 is connected between the chopper voltage regulation transistor Q1 and the inductor L1, and the second pole of the freewheeling diode U2 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge; the first pole of the capacitor C3 is connected between the second pole of the inductor L1 and the first pole of the three-phase bridge, and the second pole of the capacitor C3 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge.

[0016] Optionally, the three-phase bridge includes three bridge arms and three load inductors, the three bridge arms are arranged in parallel, each bridge arm is connected to a corresponding load inductor, and is connected to the voltage isolation module through the load inductor, the first pole of each bridge arm is connected to the second pole of the inductor L1 and the first pole of the capacitor C3, and the second pole of each bridge arm is connected to the second pole of the capacitor C3, the second pole of the freewheeling diode U2 and the common end of the second pole of the capacitor C2;

[0017] The first bridge arm includes a transistor U3 and a transistor U4, the second bridge arm includes a transistor U5 and a transistor U6, and the third bridge arm includes a transistor U7 and a transistor U8. The phase connection point between the transistor U3 and the transistor U4 is connected to the first pole of the load inductor L4, the phase connection point between the transistor U5 and the transistor U6 is connected to the first pole of the load inductor L3, and the phase connection point between the transistor U7 and the transistor U8 is connected to the first pole of the load inductor L2.

[0018] Optionally, the voltage isolation module includes a primary winding, a secondary winding and a capacitor group, the primary winding is arranged corresponding to the secondary winding, the common end of the first poles of the three inductors in the secondary winding is connected to the common end of the second poles of the three capacitors in the capacitor group and the zero voltage, and the second pole of each inductor in the secondary winding is connected to the first pole of the corresponding capacitor in the capacitor group and the load.

[0019] Optionally, the first pole of the inductor L5 in the primary winding is connected to the second pole of the load inductor L2 and the second pole of the inductor L7 in the primary winding, the second pole of the inductor L5 is connected to the second pole of the load inductor L3 and the first pole of the inductor L6 in the primary winding, and the second pole of the inductor L6 is connected to the second pole of the load inductor L4 and the first pole of the inductor L7.

[0020] An isolated three-phase power supply control method is applied to the above-mentioned isolated three-phase power supply structure, comprising:

[0021] Sending a first drive signal to a chopping voltage regulation module of an isolated three-phase power supply structure, and sending a second drive signal to a three-phase bridge of the isolated three-phase power supply structure;

[0022] The chopping voltage regulation module adjusts the switch state of the chopping voltage regulation transistor Q1 of the chopping voltage regulation module according to the first driving signal to adjust the direct current output by the conversion module to obtain adjusted direct current;

[0023] In a switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second driving signal to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module.

[0024] Optionally, within one switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second driving signal to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module, including:

[0025] A switching cycle includes 6 time periods, namely, 0-t1 period, t1-t2 period, t2-t3 period, t3-t4 period, t4-t5 period and t5-t6 period;

[0026] In the 0-t1 period, the transistor U3, the transistor U6 and the transistor U7 in the three-phase bridge are controlled to be in an on state, and the transistor U4, the transistor U5 and the transistor U8 in the three-phase bridge are controlled to be in an off state, so as to generate a U-phase alternating current and a W-phase alternating current, and the U-phase alternating current and the W-phase alternating current are output through the voltage isolation module;

[0027] During the period t1-t2, the transistor U3, the transistor U6 and the transistor U8 in the three-phase bridge are controlled to be in an on state, and the transistor U4, the transistor U5 and the transistor U7 are controlled to be in an off state, so as to generate a U-phase alternating current, and the U-phase alternating current is output through the voltage isolation module;

[0028] During the t2-t3 period, the transistor U3, the transistor U5 and the transistor U8 of the three-phase bridge are controlled to be in an on state, and the transistor U4, the transistor U6 and the transistor U7 are controlled to be in an off state, so as to generate a U-phase alternating current and a V-phase alternating current, and the U-phase alternating current and the V-phase alternating current are output through the voltage isolation module.

[0029] Optionally, within one switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second driving signal to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module, further comprising:

[0030] In the time period t3-t4, the transistor U4, the transistor U5 and the transistor U8 are controlled to be in an on state, and the transistor U3, the transistor U6 and the transistor U7 are controlled to be in an off state, so as to generate a V-phase alternating current, and the V-phase alternating current is output through the voltage isolation module to drive an external circuit;

[0031] In the time period t4-t5, the transistor U4, the transistor U5 and the transistor U7 are controlled to be in an on state, and the transistor U3, the transistor U6 and the transistor U8 are controlled to be in an off state, so as to generate a V-phase alternating current and a W-phase alternating current, and the V-phase alternating current and the W-phase alternating current are output through the voltage isolation module to drive an external circuit;

[0032] During the t5-t6 period, the transistor U4, the transistor U6 and the transistor U7 are controlled to be in the on state, and the transistor U3, the transistor U5 and the transistor U8 are controlled to be in the off state, so as to generate a W-phase alternating current, and the W-phase alternating current is output through the voltage isolation module to drive the external circuit.

[0033] Optionally, the chopping voltage regulation module adjusts the switching state of the chopping voltage regulation transistor Q1 of the chopping voltage regulation module according to the first driving signal to adjust the direct current output by the conversion module to obtain adjusted direct current, including:

[0034] Controlling the switch state of the chopper voltage regulating transistor Q1 according to the first driving signal, thereby controlling the current flow of the inductor L1, and obtaining a corresponding adjusted direct current output voltage Uo according to the current flow of the inductor L1;

[0035] When the current flow of the inductor L1 is in a continuous state, Uo=D·Ui, wherein Uo is the output voltage of the adjusted direct current obtained after adjustment by the chopper voltage regulation module, D is the duty cycle of the chopper voltage regulation transistor Q1, and Ui is the DC input voltage of the direct current converted by the conversion module;

[0036] When the current flow of the inductor L1 is in a discontinuous state, Wherein, Ton is the on time of the chopper voltage regulating transistor Q1, Toff is the off time of the chopper voltage regulating transistor Q1, and Toff1 is the time period when the inductor L1 has current.

[0037] Implementing one of the above technical solutions of the present invention has the following advantages or beneficial effects:

[0038] 1. The present invention sets a voltage isolation module in the isolated three-phase power supply structure. The voltage isolation module is equivalent to a transformer to isolate the three-phase output power supply, isolate electromagnetic interference and common mode noise, etc., with higher efficiency, lower cost and circuit protection.

[0039] 2. The present invention can respond quickly to load changes and maintain the stability of the output voltage or current by adding a chopper voltage regulator module to the structure. At the same time, energy transfer is achieved through the high-frequency switching operation of the chopper voltage regulator transistor Q1. The switch device has a small resistance when it is turned on and a small leakage current when it is turned off, which reduces power loss. Compared with the linear voltage regulator, this solution has higher efficiency and less power loss and energy loss. In addition, this solution integrates the chopper voltage regulator module with the three-phase power circuit, with high integration, and can be flexibly configured according to demand to meet different power and voltage requirements. In addition, after the chopper voltage regulator circuit is set, the circuit described in this solution can also use PWM technology to fine-tune the power circuit to ensure the stability of the output voltage or current and improve the safety and reliability of the application terminal.

[0040] 3. The three-phase bridge in the present invention generates alternating current by controlling the full-bridge circuit in different power cycles and different power time periods, and performs voltage isolation through the voltage isolation module, so that the power output is more stable, the reliability is higher, and the safety performance is better.

[0041] 4. The present invention uses a conversion module to convert AC power into DC power instead of a DC power supply, which can be applied to more application scenarios and save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. It is obvious that the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0043] Figure 1 is a schematic structural diagram of an isolated three-phase power supply structure according to an embodiment of the present invention;

[0044] Figure 2 1 is a schematic diagram of current flow direction in the period 0-t1 of the isolated three-phase power supply control method according to an embodiment of the present invention;

[0045] Figure 3 1 is a schematic diagram of current flow during the period t1-t2 of the isolated three-phase power supply control method according to an embodiment of the present invention;

[0046] Figure 4 1 is a schematic diagram of current flow during the period t2-t3 of the isolated three-phase power supply control method according to an embodiment of the present invention;

[0047] Figure 5 1 is a schematic diagram of current flow during the period t3-t4 of the isolated three-phase power supply control method according to an embodiment of the present invention;

[0048] Figure 6 1 is a schematic diagram of current flow during the period t4-t5 of the isolated three-phase power supply control method according to an embodiment of the present invention;

[0049] Figure 7 1 is a schematic diagram of current flow during the period t5-t6 of the isolated three-phase power supply control method according to an embodiment of the present invention;

[0050] Figure 8 It is a signal schematic diagram of a switching cycle of a three-phase bridge in the isolated three-phase power supply control method according to an embodiment of the present invention;

[0051] Fig. 9 It is a flow chart of a method for controlling an isolated three-phase power supply according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention clearer, the various exemplary embodiments to be described below will refer to the corresponding drawings, which constitute a part of the exemplary embodiments, wherein various exemplary embodiments that may be used to implement the present invention are described. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present disclosure. It should be understood that they are only examples of processes, methods, devices, etc. that are consistent with some aspects of the present disclosure as detailed in the attached claims, and other embodiments may also be used, or the embodiments listed herein may be modified in structure and function without departing from the scope and essence of the present invention.

[0053] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", etc. indicate the orientation or positional relationship based on the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the elements referred to must have a specific orientation, be constructed and operated in a specific orientation. The terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "multiple" means two or more. The terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a communication connection, a direct connection, an indirect connection through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0054] In order to illustrate the technical solution of the present invention, a specific embodiment is used below for description, and only the parts related to the embodiment of the present invention are shown.

[0055] Embodiment 1:

[0056] like Figure 1As shown, the present invention provides an isolated three-phase power supply structure, including: a conversion module, a chopping voltage regulation module, a three-phase bridge and a voltage isolation module connected in sequence, the conversion module is used to convert AC power into DC power, the chopping voltage regulation module is used to adjust DC power, the three-phase bridge is used to convert the adjusted DC power into three-phase AC power, and the voltage isolation module is used to electrically isolate the three-phase AC power and output the isolated three-phase AC power to the load. Specifically, the conversion module, the chopping voltage regulation module, the three-phase bridge and the voltage isolation module are connected in sequence, the conversion module converts AC power into DC power and then transmits it to the chopping voltage regulation module, the DC power is adjusted by the chopping voltage regulation module, and the adjusted DC power is transmitted to the three-phase bridge, and then the adjusted DC power is converted into three-phase AC power by the three-phase bridge and transmitted to the voltage isolation module, and then the three-phase AC power is electrically isolated by the voltage isolation module, and the isolated three-phase AC power is output to the load, and the load is powered to meet the use requirements of the three-phase load. Setting a voltage isolation module between the load and the three-phase bridge can electrically isolate and protect the power supply, solving the problems of electromagnetic interference and electric shock risks of non-isolated power supply.

[0057] The present invention provides a voltage isolation module in an isolated three-phase power supply structure, and the voltage isolation module is equivalent to a transformer, so as to isolate the three-phase output power supply, isolate electromagnetic interference and common mode noise, etc., with higher efficiency, lower cost and circuit protection.

[0058] The present invention can quickly respond to load changes and maintain the stability of the output voltage or current by adding a chopper voltage regulator module to the structure. At the same time, energy transfer is achieved through the high-frequency switching operation of the chopper voltage regulator transistor Q1. The switch device has a small resistance when it is turned on and a small leakage current when it is turned off, which reduces power loss. Compared with the linear voltage regulator, this solution has higher efficiency and less power loss and energy loss. In addition, the present solution integrates the chopper voltage regulator module with the three-phase power circuit, with high integration, and can be flexibly configured according to demand to meet different power and voltage requirements. In addition, after the chopper voltage regulator circuit is set, the circuit described in this solution can also use PWM technology to fine-tune the power circuit to ensure the stability of the output voltage or current and improve the safety and reliability of the application terminal.

[0059] As an optional implementation, the conversion module includes an AC power supply U1 and a rectifier bridge D1, the third pole of the rectifier bridge D1 is connected to the first pole of the AC power supply U1, the fourth pole of the rectifier bridge D1 is connected to the second pole of the AC voltage, the first pole and the second pole of the rectifier bridge D1 are connected to the chopper voltage regulation module, and the rectifier bridge D1 is used to rectify the AC power output by the AC power supply U1 into DC power. Specifically, the conversion module rectifies the AC power output by the AC power supply U1 into DC power through the rectifier bridge D1, so that the isolated three-phase power supply structure can be flexibly applied to more scenarios, such as household electricity is AC power. At the same time, there is no need to set a power supply anti-reverse circuit, which saves costs. The rectifier bridge D1 is composed of four rectifier diodes.

[0060] As an optional embodiment, the chopper voltage regulation module includes a chopper voltage regulation transistor Q1, an inductor L1, a freewheeling diode U2, a capacitor C1, a capacitor C2 and a capacitor C3, and the chopper voltage regulation transistor Q1 and the inductor L1 are arranged in series between the first pole of the rectifier bridge D1 and the first pole of the three-phase bridge. Capacitor C1 is connected in series with capacitor C2, and the first pole of capacitor C1 is connected between the first pole of the rectifier bridge D1 and the first pole of the chopper voltage regulation transistor Q1, and the second pole of capacitor C2 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge. The first pole of the freewheeling diode U2 is connected between the chopper voltage regulation transistor Q1 and the inductor L1, and the second pole of the freewheeling diode U2 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge. The first pole of capacitor C3 is connected between the second pole of inductor L1 and the first pole of the three-phase bridge, and the second pole of capacitor C3 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge. Specifically, the chopper voltage regulation module of the present invention adopts a step-down chopper circuit that converts a higher input voltage into a lower output voltage. In the chopper voltage regulation module, a suitable capacitance value can also be selected according to the actual application scenario, so as to select a capacitor C1, a capacitor C2, or a capacitor C1 and a capacitor C2 to be connected between the first pole of the rectifier bridge D1 and the first pole of the chopper voltage regulation transistor Q1. The chopper voltage regulation transistor Q1 can be selected as an NMOS tube and a PMOS tube, preferably an NMOS tube. The chopper voltage regulation transistor Q1 is used as a switch tube of the chopper circuit. The chopper voltage regulation transistor Q1 controls the energy transfer from the power supply to the load by quickly turning on and off, and the switch device has a small resistance when it is turned on and a small leakage current when it is turned off, which reduces power loss. Compared with the linear regulator, the present invention has higher efficiency and less power loss and energy loss. When the chopper voltage regulation transistor Q1 is turned on, the current flows from the power supply to the load; when the chopper voltage regulation transistor Q1 is turned off, the current is interrupted and the voltage on the load is reduced. At the same time, this embodiment can also control the on-time (duty cycle) of the chopper voltage regulator transistor Q1 through a PWM signal to perform chopper voltage regulation, thereby achieving precise control of the output voltage and meeting the voltage requirements in different application scenarios. For example, in step-down chopping, by extending the on-time of the chopper voltage regulator transistor Q1, the circuit generates a higher duty cycle and thus generates a higher output voltage; by shortening the on-time of the chopper voltage regulator transistor Q1, the circuit generates a lower duty cycle and thus generates a lower output voltage.

[0061] Further, when the chopper voltage regulator transistor Q1 is turned on, the conversion module supplies power to the load through the inductor L1, and the inductor L1 stores energy. At this time, the current in the inductor L1 gradually increases, and the energy stored therein exists in the form of a magnetic field. When the chopper voltage regulator transistor Q1 is turned off, the magnetic field in the inductor L1 begins to decay, and the energy stored therein is released through the freewheeling diode U2 or the load. More specifically, during the energy release process, the inductor L1 can enable the current in the circuit to flow continuously, and even during the period when the chopper voltage regulator transistor Q1 is turned off, it is ensured that the current on the load will not be suddenly interrupted, ensuring the continuity of the output current and ensuring the stability of the load application circuit. The freewheeling diode U2 can provide a freewheeling path and suppress the back electromotive force to ensure the safety and stability of the circuit. Capacitors C1, C2, and C3 are used for energy storage and energy transfer to ensure the safety and stability of the circuit operation. For example, when a sudden change in the power supply occurs in the power circuit, the circuit will not suddenly stop working, causing the applied transistor to be damaged due to a sudden change in voltage, so that the circuit can stop working smoothly, ensuring the safety of the terminal application.

[0062] As an optional implementation, the three-phase bridge includes three bridge arms and three load inductors, the three bridge arms are arranged in parallel, each bridge arm is connected to a corresponding load inductor, and is connected to the voltage isolation module through the load inductor, the first pole of each bridge arm is connected to the second pole of the inductor L1 and the first pole of the capacitor C3, and the second pole of each bridge arm is connected to the second pole of the capacitor C3, the second pole of the freewheeling diode U2, and the common end of the second pole of the capacitor C2. The first bridge arm includes a transistor U3 and a transistor U4, the second bridge arm includes a transistor U5 and a transistor U6, and the third bridge arm includes a transistor U7 and a transistor U8, the phase connection point of the transistor U3 and the transistor U4 is connected to the first pole of the load inductor L4, the phase connection point of the transistor U5 and the transistor U6 is connected to the first pole of the load inductor L3, and the phase connection point of the transistor U7 and the transistor U8 is connected to the first pole of the load inductor L2. Specifically, the three-phase bridge generates an alternating current by controlling the full-bridge circuit in different power cycles and different power time periods, and performs electrical isolation through the voltage isolation module, so that the power output is more stable, the reliability is higher, and the safety performance is better. The three bridge arms are respectively the first bridge arm, the second bridge arm and the third bridge arm. The load inductor L4 is connected between the second pole of the transistor U3 and the first pole of the transistor U4, the load inductor L3 is connected between the second pole of the transistor U5 and the first pole of the transistor U6, and the load inductor L2 is connected between the second pole of the transistor U7 and the first pole of the transistor U8. The transistor in the present invention is a parallel structure of IGBT and FRD, or it can be other types of triodes such as MOSFET. The load inductor L2, the load inductor L3, and the load inductor L4 act as the inductive load of the three-phase bridge, or are equivalent to the stray inductance of the loop, and can store energy, filter and stabilize the current generated in the circuit, so that the circuit works more stably, and at the same time can improve the corresponding speed of the circuit. The chopper voltage regulation module of the present invention supports multiple stages of bridge arms connected in series or in parallel to meet different power and voltage requirements.

[0063] As an optional implementation, the voltage isolation module includes a primary winding, a secondary winding and a capacitor group, the primary winding is arranged corresponding to the secondary winding, the common end of the first poles of the three inductors in the secondary winding is connected to the common end of the second poles of the three capacitors in the capacitor group and the zero voltage, and the second pole of each inductor in the secondary winding is connected to the first pole of the capacitor in the corresponding capacitor group and the load. Specifically, the three inductors in the primary winding are inductor L5, inductor L6 and inductor L7, and the three inductors in the secondary winding are inductor L8, inductor L9 and inductor L10. Based on the law of electromagnetic induction, the primary winding and the secondary winding transfer energy between windings with different numbers of turns through an alternating magnetic field to achieve voltage increase or decrease. The capacitor group includes capacitor C4, capacitor C5 and capacitor C6. The common end of the first pole of inductor L8, the first pole of inductor L9 and the first pole of inductor L10 is connected to the common end of the second pole of capacitor C4, the second pole of capacitor C5 and the second pole of capacitor C6 and the zero voltage N of the three-phase output power supply. The second pole of inductor L8 is connected to the first pole of capacitor C6, the second pole of inductor L9 is connected to the first pole of capacitor C5, and the second pole of inductor L10 is connected to the first pole of capacitor C4. The second pole of inductor L8 outputs W-phase alternating current, the second pole of inductor L9 outputs V-phase alternating current, and the second pole of inductor L10 outputs U-phase alternating current. The capacitor group is used to eliminate high-frequency noise at the output end and improve the stability of the isolated three-phase power supply structure.

[0064] As an optional implementation, the first pole of the inductor L5 in the primary winding is connected to the second pole of the load inductor L2 and the second pole of the inductor L7 in the primary winding, the second pole of the inductor L5 is connected to the second pole of the load inductor L3 and the first pole of the inductor L6 in the primary winding, and the second pole of the inductor L6 is connected to the second pole of the load inductor L4 and the first pole of the inductor L7. Specifically, the inductors L5, L6 and L7 in the primary winding are connected to form a triangular three-phase electricity, and the inductors L8, L9 and L10 in the secondary winding are connected to form a star three-phase electricity. The voltage isolation module isolates and transforms the triangular three-phase electricity into a star three-phase electricity. The present invention forms an equivalent transformer through an inductor combination, isolates the three-phase output power supply, isolates electromagnetic interference and common mode noise, etc., and has higher efficiency and lower cost.

[0065] Embodiment 2:

[0066] like Fig. 9 As shown, the present invention also provides an isolated three-phase power supply control method, which is applied to the isolated three-phase power supply structure as in the first embodiment, comprising:

[0067] S10, sending a first drive signal to a chopping voltage regulation module of an isolated three-phase power supply structure, and sending a second drive signal to a three-phase bridge of the isolated three-phase power supply structure;

[0068] S20, the chopping voltage regulation module adjusts the switch state of the chopping voltage regulation transistor Q1 of the chopping voltage regulation module according to the first driving signal to adjust the direct current output by the conversion module to obtain adjusted direct current;

[0069] S30. In a switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second drive signal to convert the adjusted direct current into three-phase alternating current, and output the three-phase alternating current through the voltage isolation module. Specifically, after the isolated three-phase power supply structure obtains the first drive signal, the chopping voltage regulation module can adjust the direct current output by the conversion module according to the first drive signal obtained, quickly respond to load changes, adjust the voltage or current of the direct current, ensure the stability of the output voltage or current, ensure the safety of the circuit, and improve the flexibility of circuit application. After the isolated three-phase power supply structure obtains the second drive signal, it can control the conduction state of each bridge arm of the three-phase bridge according to the second control signal, so that the three-phase bridge generates corresponding three-phase alternating current and transmits it to the load. The three-phase alternating current includes W-phase alternating current, V-phase alternating current and U-phase alternating current.

[0070] The present invention realizes multi-faceted control of the control circuit through the first drive signal and the second drive signal, with high integration and low cost. At the same time, the output voltage can be adjusted according to the first drive signal to adapt to usage scenarios with different voltage requirements, and the conduction state of each bridge arm of the three-phase bridge can be adjusted according to the power time period of the switching cycle, thereby ensuring the safety and stability of the isolated three-phase power supply structure, and further ensuring the stability of the load application.

[0071] As an optional implementation, within a switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second drive signal to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module, including:

[0072] like Figure 8 As shown, a switching cycle includes 6 time periods, namely, 0-t1 period, t1-t2 period, t2-t3 period, t3-t4 period, t4-t5 period and t5-t6 period;

[0073] like Figure 2As shown, during the time period 0-t1, the transistor U3, the transistor U6 and the transistor U7 in the three-phase bridge are controlled to be in the on state, and the transistor U4, the transistor U5 and the transistor U8 in the three-phase bridge are controlled to be in the off state, so that the U-phase alternating current and the W-phase alternating current are generated, and the U-phase alternating current and the W-phase alternating current are output through the voltage isolation module. Specifically, during the 0-t1 period, the transistor U3, the transistor U6 and the transistor U7 receive a high-level signal and are thus in an on state, while the transistor U4, the transistor U5 and the transistor U8 receive a low-level signal and are thus in an off state, thereby controlling the direction of the current flow, so that the current starts from the first pole of the AC power supply U1, passes through the rectifier bridge D1, the chopper voltage regulator transistor Q1, and the inductor L1 in sequence, and then flows to the transistor U3 and the transistor U7 respectively, the current passing through the transistor U3 flows to the load inductor L4 and the inductor L7 in sequence, the current passing through the transistor U7 flows to the load inductor L2 and the inductor L5 in sequence, the current passing through the inductor L5 and the inductor L7 both flows to the inductor L6, the load inductor L3, the transistor U6 and the rectifier bridge D1 in sequence, and finally flows to the second pole of the AC power supply U1, so that the three-phase bridge converts the DC power into U-phase alternating current and W-phase alternating current, and transmits them to the load through the voltage isolation module.

[0074] like Figure 3 As shown, during the period t1-t2, the transistors U3, U6 and U8 in the three-phase bridge are controlled to be in the on state, and the transistors U4, U5 and U7 are controlled to be in the off state, so as to generate a U-phase alternating current, and output the U-phase alternating current through the voltage isolation module. Specifically, during the time period t1-t2, transistor U3, transistor U6 and transistor U8 receive a high-level signal and are thus in an on state, while transistor U4, transistor U5 and transistor U7 receive a low-level signal and are thus in an off state, thereby controlling the direction of current flow, so that the current starts from the first pole of the AC power supply U1, passes through the rectifier bridge D1, the chopper voltage regulating transistor Q1, the inductor L1, the transistor U3, the load inductor L4 and the inductor L7 in sequence, and then flows to the inductor L7 to flow to the inductor L6 and the load inductor L2 respectively, the current passing through the inductor L6 passes through the load inductor L3 and the transistor U6 in sequence, the current passing through the load inductor L2 passes through the transistor U8, and finally the current passing through the transistor U6 and the transistor U8 is converged to the second pole of the AC power supply U1 of the conversion module, so that the three-phase bridge converts the DC power into a U-phase alternating current, and transmits it to the load through the voltage isolation module.

[0075] like Figure 4As shown, during the time period t2-t3, the transistor U3, the transistor U5 and the transistor U8 of the three-phase bridge are controlled to be in the on state, and the transistor U4, the transistor U6 and the transistor U7 are controlled to be in the off state, so that the U-phase alternating current and the V-phase alternating current are generated, and the U-phase alternating current and the V-phase alternating current are output through the voltage isolation module. Specifically, during the time period t2-t3, transistor U3, transistor U5 and transistor U8 receive a high-level signal and are thus in an on state, while transistor U4, transistor U6 and transistor U7 receive a low-level signal and are thus in an off state, thereby controlling the direction of current flow, so that the current starts from the first pole of the AC power supply U1, passes through the rectifier bridge D1, the chopper voltage regulator transistor Q1, and the inductor L1 in sequence, and then flows to transistor U3 and transistor U5 respectively. The current passing through transistor U3 flows to the load inductor L4 and inductor L7 in sequence, and the current passing through transistor U5 flows to the load inductor L3, inductor L6 and inductor L5 in sequence. The current passing through inductor L7 and inductor L5 both flows to the load inductor L2, transistor U8 and rectifier bridge D1 in sequence, and finally flows to the second pole of the AC power supply U1, so that the three-phase bridge converts DC power into U-phase alternating current and V-phase alternating current, and transmits them to the load through the voltage isolation module.

[0076] like Figure 5 As shown, during the period t3-t4, transistor U4, transistor U5 and transistor U8 are controlled to be in the on state, and transistor U3, transistor U6 and transistor U7 are controlled to be in the off state, so as to generate a V-phase alternating current, and the V-phase alternating current is output through the voltage isolation module to drive the external circuit. Specifically, during the time period t3-t4, transistor U4, transistor U5 and transistor U8 receive a high-level signal and are thus in an on state, while transistor U3, transistor U6 and transistor U7 receive a low-level signal and are thus in an off state, thereby controlling the direction of current flow, so that the current starts from the first pole of the AC power supply U1, passes through the rectifier bridge D1, the chopper voltage regulating transistor Q1, the inductor L1, the transistor U5, the load inductor L3 and the inductor L6 in sequence, the current passing through the inductor L6 flows to the inductor L5 and the inductor L7 respectively, the current passing through the inductor L5 flows to the load inductor L2 and the transistor U8 in sequence, the current passing through the inductor L7 flows to the load inductor L4 and the transistor U4 in sequence, and finally the current passing through the transistor U4 and the transistor U8 is converged to the second pole of the AC power supply U1 of the conversion module, so that the three-phase bridge converts the DC power into a V-phase alternating current, and transmits it to the load through the voltage isolation module.

[0077] like Figure 6As shown, during the time period t4-t5, the transistors U4, U5 and U7 are controlled to be in the on state, and the transistors U3, U6 and U8 are controlled to be in the off state, so that V-phase alternating current and W-phase alternating current are generated, and the V-phase alternating current and W-phase alternating current are output through the voltage isolation module to drive the external circuit. Specifically, during the time period t4-t5, transistor U4, transistor U5 and transistor U7 receive a high-level signal and are thus in an on state, while transistor U3, transistor U6 and transistor U8 receive a low-level signal and are thus in an off state, thereby controlling the direction of current flow, so that the current starts from the first pole of the AC power supply U1, passes through the rectifier bridge D1, the chopper voltage regulator transistor Q1 and the inductor L1 in sequence, and then flows to transistor U5 and transistor U7 respectively. The current passing through transistor U5 flows to the load inductor L3, inductor L6 and inductor L7 in sequence, and the current passing through transistor U7 flows to the load inductor L2 and inductor L5 in sequence, and finally converges to the inductor L7 through the inductor L6. The current converged to the inductor L7 passes through the load inductor L4, transistor U4 and the rectifier bridge D1 in sequence, and finally flows to the second pole of the AC power supply U1, so that the three-phase bridge converts the DC power into V-phase alternating current and W-phase alternating current, and transmits them to the load through the voltage isolation module.

[0078] like Figure 7 As shown, during the period t5-t6, the transistors U4, U6 and U7 are controlled to be in the on state, while the transistors U3, U5 and U8 are controlled to be in the off state, so as to generate a W-phase alternating current, and the W-phase alternating current is output through the voltage isolation module to drive the external circuit. Specifically, during the time period t5-t6, transistor U4, transistor U6 and transistor U7 receive a high-level signal and are thus in an on state, while transistor U3, transistor U5 and transistor U8 receive a low-level signal and are thus in an off state, thereby controlling the direction of current flow, so that the current starts from the first pole of the AC power supply U1, passes through the rectifier bridge D1, the chopper voltage regulating transistor Q1, the inductor L1, the transistor U7, the load inductor L2 and the inductor L5 in sequence, and the current passing through the inductor L5 flows to the inductor L6, the load inductor L3 and the transistor U6 in sequence, while the current passing through the inductor L5 flows to the inductor L7, the load inductor L4 and the transistor U4 in sequence through the inductor L6, and finally the current passing through the transistor U6 and the transistor U4 is converged to the second pole of the AC power supply U1 of the conversion module, so that the three-phase bridge converts the DC power into a W-phase alternating current, and transmits it to the load through the voltage isolation module.

[0079] As an optional implementation, the chopping voltage regulation module adjusts the switch state of the chopping voltage regulation transistor Q1 of the chopping voltage regulation module according to the first driving signal to adjust the direct current output by the conversion module to obtain the adjusted direct current, including:

[0080] Controlling the switch state of the chopper voltage regulating transistor Q1 according to the first driving signal, thereby controlling the current flow of the inductor L1, and obtaining the corresponding adjusted direct current output voltage Uo according to the current flow of the inductor L1;

[0081] When the current flow of the inductor L1 is in a continuous state, Uo=D·Ui, wherein Uo is the output voltage of the regulated DC power obtained after the adjustment by the chopper voltage regulation module, D is the duty cycle of the chopper voltage regulation transistor Q1, and Ui is the DC input voltage of the DC power converted by the conversion module;

[0082] When the current flow of inductor L1 is in a discontinuous state, Wherein, Ton is the on time of the chopper voltage regulator transistor Q1, Toff is the off time of the chopper voltage regulator transistor Q1, and Toff1 is the period when the inductor L1 has current. Specifically, the chopper voltage regulator module adjusts the switching state of the chopper voltage regulator transistor Q1 of the chopper voltage regulator module according to the first drive signal. When the first drive signal is the on signal of the chopper voltage regulator transistor Q1 of the chopper voltage regulator module, the isolated three-phase power supply structure controls the chopper voltage regulator transistor Q1 to be turned on, so that the current output by the conversion module supplies power to the load through the inductor L1. When the first drive signal is the off signal of the chopper voltage regulator transistor Q1 of the chopper voltage regulator module, the isolated three-phase power supply structure controls the chopper voltage regulator transistor Q1 to be turned off, so that the current is interrupted, thereby reducing the voltage of the load. At the same time, the chopper voltage regulation module can also control the on-time (duty cycle) of the chopper voltage regulation transistor Q1 according to the first drive signal. If the first drive signal is a signal for increasing the output voltage of the DC motor multiplexing control circuit, the DC motor multiplexing control circuit controls the on-time of the chopper voltage regulation transistor Q1 to be extended, so that the circuit generates a higher duty cycle and thus generates a higher output voltage. If the first drive signal is a signal for reducing the output voltage of the DC motor multiplexing control circuit, the DC motor multiplexing control circuit controls the on-time of the chopper voltage regulation transistor Q1 to be shortened, so that the circuit generates a lower duty cycle and thus generates a lower output voltage.

[0083] Furthermore, when the chopper voltage regulator transistor Q1 is turned on, the conversion module supplies power to the load through the inductor L1, and the inductor L1 stores energy. At this time, the current in the inductor L1 gradually increases, and the energy stored in it exists in the form of a magnetic field. When the chopper voltage regulator transistor Q1 is turned off, the magnetic field in the inductor L1 begins to decay, and the energy stored in the inductor L1 can be released through the freewheeling diode U2 or the load. Therefore, by controlling the conduction state and conduction time (duty cycle) of the chopper voltage regulator transistor Q1, the current flow of the inductor L1 can be controlled.

[0084] For example, the current flow of the inductor L1 is in a continuous state in the following cases: First, between two adjacent switching cycles, the inductor L1 can release energy and continue to supply power to the load. At this time, the energy of the inductor L1 has not been fully released, and the next switching cycle begins, and the chopper voltage regulator transistor Q1 is turned on, which can make the current flow of the inductor L1 in a continuous state. Second, when the switching frequency of the chopper voltage regulator transistor Q1 is low, each cycle will be longer, so that the inductor L1 has enough time to complete the entire energy release process during the shutdown period, and the inductor L1 will continue to store current at the beginning of the next cycle, ensuring that the current flow of the inductor L1 is in a continuous state in each cycle. Third, the duty cycle of the chopper voltage regulator transistor Q1 is relatively high, and the inductor L1 has a longer charging time, so that the current of the inductor L1 will not drop to zero during the shutdown period of the chopper voltage regulator transistor Q1.

[0085] The current flow of the inductor L1 is in a discontinuous state in the following situations: First, between two adjacent switching cycles, when the inductor L1 releases energy and continues to supply power to the load, after the energy of the inductor L1 is released, the next switching cycle has not yet started, and the chopper voltage regulator transistor Q1 is disconnected, which will cause the current to be unable to flow to the inductor L1, so that there is a blank period of zero current between two adjacent switching cycles, resulting in the current flow of the inductor L1 being in a discontinuous state. Second, under light load conditions, the energy demand in the inductor L1 is low, and at the end of each cycle, the current of the inductor L1 may be completely exhausted and drop to zero. Third, when the switching frequency of the chopper voltage regulator transistor Q1 is high, the time of each cycle will be shorter, so that the inductor L1 does not have enough time to complete the entire energy release process during the shutdown period, which will make the current of the inductor L1 unable to maintain continuity in some cycles. Fourth, the duty cycle of the chopper voltage regulator transistor Q1 is low, resulting in a short charging time for the inductor L1, and the current of the inductor L1 may drop to zero during the shutdown period of the chopper voltage regulator transistor Q1.

[0086] The output voltage Uo output by the chopper voltage regulation module needs to consider whether the current flow of the inductor L1 is in a continuous state. When the current flow of the inductor L1 is in a continuous state, the calculation method of the output voltage Uo is Uo = D Ui. When the current flow of the inductor L1 is in a discontinuous state, the calculation method of the output voltage Uo is Due to the existence of inductor L1, the off time Toff of chopper voltage regulator transistor Q1 is divided into the period Toff1 when inductor L1 has current and the period Toff2 when inductor L1 has no current. The required voltage can be obtained according to the calculation method of output voltage Uo. A small voltage of tens of volts is suitable for fans, electric lifts, etc., and a large voltage of hundreds or thousands of volts is suitable for industrial products.

[0087] The above description is only the preferred embodiment of the present invention. It is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the protection scope of the present invention.

Claims

1. An isolated three-phase power supply structure, characterized in that: include: A conversion module, a chopper voltage regulation module, a three-phase bridge and a voltage isolation module connected in sequence; The conversion module is used to convert alternating current into direct current; The chopper voltage regulation module is used to regulate direct current; The three-phase bridge is used to convert the regulated direct current into three-phase alternating current; The voltage isolation module is used to electrically isolate the three-phase alternating current and output the isolated three-phase alternating current to the load.

2. The isolated three-phase power supply structure according to claim 1, characterized in that: The conversion module includes an AC power supply U1 and a rectifier bridge D1, the third pole of the rectifier bridge D1 is connected to the first pole of the AC power supply U1, the fourth pole of the rectifier bridge D1 is connected to the second pole of the AC voltage, the first pole and the second pole of the rectifier bridge D1 are connected to the chopper voltage regulation module, and the rectifier bridge D1 is used to rectify the AC power output by the AC power supply U1 into DC power.

3. The isolated three-phase power supply structure according to claim 2, characterized in that: The chopper voltage regulation module includes a chopper voltage regulation transistor Q1, an inductor L1, a freewheeling diode U2, a capacitor C1, a capacitor C2 and a capacitor C3. The chopper voltage regulation transistor Q1 and the inductor L1 are connected in series between the first pole of the rectifier bridge D1 and the first pole of the three-phase bridge; the capacitor C1 is connected in series with the capacitor C2, and the first pole of the capacitor C1 is connected between the first pole of the rectifier bridge D1 and the first pole of the chopper voltage regulation transistor Q1, and the second pole of the capacitor C2 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge; the first pole of the freewheeling diode U2 is connected between the chopper voltage regulation transistor Q1 and the inductor L1, and the second pole of the freewheeling diode U2 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge; the first pole of the capacitor C3 is connected between the second pole of the inductor L1 and the first pole of the three-phase bridge, and the second pole of the capacitor C3 is connected between the second pole of the rectifier bridge D1 and the second pole of the three-phase bridge.

4. The isolated three-phase power supply structure according to claim 3, characterized in that: The three-phase bridge includes three bridge arms and three load inductors, the three bridge arms are arranged in parallel, each bridge arm is connected to a corresponding load inductor, and is connected to the voltage isolation module through the load inductor, the first pole of each bridge arm is connected to the second pole of the inductor L1 and the first pole of the capacitor C3, and the second pole of each bridge arm is connected to the second pole of the capacitor C3, the second pole of the freewheeling diode U2 and the common end of the second pole of the capacitor C2; The first bridge arm includes a transistor U3 and a transistor U4, the second bridge arm includes a transistor U5 and a transistor U6, and the third bridge arm includes a transistor U7 and a transistor U8. The phase connection point between the transistor U3 and the transistor U4 is connected to the first pole of the load inductor L4, the phase connection point between the transistor U5 and the transistor U6 is connected to the first pole of the load inductor L3, and the phase connection point between the transistor U7 and the transistor U8 is connected to the first pole of the load inductor L2.

5. The isolated three-phase power supply structure according to claim 4, characterized in that: The voltage isolation module includes a primary winding, a secondary winding and a capacitor group. The primary winding is arranged corresponding to the secondary winding. The common end of the first poles of the three inductors in the secondary winding is connected to the common end of the second poles of the three capacitors in the capacitor group and the zero voltage. The second pole of each inductor in the secondary winding is connected to the first pole of the corresponding capacitor in the capacitor group and the load.

6. The isolated three-phase power supply structure according to claim 5, characterized in that: The first pole of the inductor L5 in the primary winding is connected to the second pole of the load inductor L2 and the second pole of the inductor L7 in the primary winding, the second pole of the inductor L5 is connected to the second pole of the load inductor L3 and the first pole of the inductor L6 in the primary winding, and the second pole of the inductor L6 is connected to the second pole of the load inductor L4 and the first pole of the inductor L7.

7. An isolated three-phase power supply control method, characterized in that: The isolated three-phase power supply structure as claimed in any one of claims 1 to 6 comprises: Sending a first drive signal to a chopping voltage regulation module of an isolated three-phase power supply structure, and sending a second drive signal to a three-phase bridge of the isolated three-phase power supply structure; The chopping voltage regulation module adjusts the switch state of the chopping voltage regulation transistor Q1 of the chopping voltage regulation module according to the first driving signal to adjust the direct current output by the conversion module to obtain adjusted direct current; In a switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second driving signal to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module.

8. The isolated three-phase power supply control method according to claim 7, characterized in that: The three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second driving signal in one switching cycle to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module, including: A switching cycle includes 6 time periods, namely, 0-t1 period, t1-t2 period, t2-t3 period, t3-t4 period, t4-t5 period and t5-t6 period; In the 0-t1 period, the transistor U3, the transistor U6 and the transistor U7 in the three-phase bridge are controlled to be in an on state, and the transistor U4, the transistor U5 and the transistor U8 in the three-phase bridge are controlled to be in an off state, so as to generate a U-phase alternating current and a W-phase alternating current, and the U-phase alternating current and the W-phase alternating current are output through the voltage isolation module; During the period t1-t2, the transistor U3, the transistor U6 and the transistor U8 in the three-phase bridge are controlled to be in an on state, and the transistor U4, the transistor U5 and the transistor U7 are controlled to be in an off state, so as to generate a U-phase alternating current, and the U-phase alternating current is output through the voltage isolation module; During the t2-t3 period, the transistor U3, the transistor U5 and the transistor U8 of the three-phase bridge are controlled to be in an on state, and the transistor U4, the transistor U6 and the transistor U7 are controlled to be in an off state, so as to generate a U-phase alternating current and a V-phase alternating current, and the U-phase alternating current and the V-phase alternating current are output through the voltage isolation module.

9. The isolated three-phase power supply control method according to claim 8, characterized in that: In one switching cycle, the three-phase bridge controls the conduction state of each bridge arm in the three-phase bridge according to the second driving signal to convert the adjusted direct current into three-phase alternating current, and outputs the three-phase alternating current through the voltage isolation module, and also includes: In the time period t3-t4, the transistor U4, the transistor U5 and the transistor U8 are controlled to be in an on state, and the transistor U3, the transistor U6 and the transistor U7 are controlled to be in an off state, so as to generate a V-phase alternating current, and the V-phase alternating current is output through the voltage isolation module to drive an external circuit; In the time period t4-t5, the transistor U4, the transistor U5 and the transistor U7 are controlled to be in an on state, and the transistor U3, the transistor U6 and the transistor U8 are controlled to be in an off state, so as to generate a V-phase alternating current and a W-phase alternating current, and the V-phase alternating current and the W-phase alternating current are output through the voltage isolation module to drive an external circuit; During the t5-t6 period, the transistor U4, the transistor U6 and the transistor U7 are controlled to be in the on state, and the transistor U3, the transistor U5 and the transistor U8 are controlled to be in the off state, so as to generate a W-phase alternating current, and the W-phase alternating current is output through the voltage isolation module to drive the external circuit.

10. The isolated three-phase power supply control method according to claim 7, characterized in that: The chopping voltage regulation module adjusts the switch state of the chopping voltage regulation transistor Q1 of the chopping voltage regulation module according to the first driving signal to adjust the direct current output by the conversion module to obtain adjusted direct current, including: Controlling the switch state of the chopper voltage regulating transistor Q1 according to the first driving signal, thereby controlling the current flow of the inductor L1, and obtaining a corresponding adjusted direct current output voltage Uo according to the current flow of the inductor L1; When the current flow of the inductor L1 is in a continuous state, Uo=D·Ui, wherein Uo is the output voltage of the adjusted direct current obtained after adjustment by the chopper voltage regulation module, D is the duty cycle of the chopper voltage regulation transistor Q1, and Ui is the DC input voltage of the direct current converted by the conversion module; When the current flow of the inductor L1 is in a discontinuous state, Wherein, Ton is the on time of the chopper voltage regulating transistor Q1, Toff is the off time of the chopper voltage regulating transistor Q1, and Toff1 is the time period when the inductor L1 has current.

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