Charging device based on four-phase open-loop winding machine driving system

Abstract

The invention discloses a charging device based on a four-phase open-loop winding machine driving system, which is characterized in that a three-phase power supply is connected with a midpoint of a stator winding in a motor winding, the stator winding is connected with bridge arms which are connected in parallel in a power converter, and finally the bridge arms are connected with a battery. Power grid current can be divided into two equal parts and flows in opposite directions, total zero balance of the charging device is achieved, a total zero average rotating magnetic field generates zero net electromagnetic torque in the charging period, then the rotor is kept at the static position, and when a zero line of a three-phase power source is connected to the center of a stator winding, the zero net electromagnetic torque is generated. According to the invention, the zero line current can be controlled to be zero by using the two parallel branches of the power converter, a three-phase balance system is realized, and the stability of the power grid charging device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of intelligent charging and relates to a charging device based on a four-phase open-loop coil generator drive system. Background Art

[0002] As the number of electric vehicles continues to rise, people's need for fast charging of electric vehicles is also increasing; in order to fully charge in a short time to ensure a long driving range, a large amount of energy needs to be delivered to the battery in a short time during charging, and a large number of power electronic devices are required to meet such high charging power requirements. Often these devices are bulky and expensive, and such devices take up more space in the car of non-integrated on-board chargers (NOBCs) and require public or private land to build non-on-board charger (OfBC) infrastructure.

[0003] The main issues with integrating charging functions into electric vehicle (EV) drive systems are: 1) When the charging current flows through the stator windings, an electromagnetic torque is generated during the charging process. This undesirable charging torque can cause the vehicle to move during charging, posing a greater safety hazard. 2) Use mechanical switches (relays) to reconfigure the system. Long-term operation of relays can cause system wear and failure. Another problem that often occurs in power grid systems is system imbalance due to factors such as nonlinear loads. The lack of a neutral line during system operation or a lack of control methods to resolve unbalanced phases can increase losses, leading to poor performance and potential system failures.

[0004] One of the disadvantages of using a Unidirectional Charging System (UCS) to charge electric vehicles is the need for a large grid infrastructure when multiple UCS vehicles are connected. Such solutions require large investments and ongoing grid maintenance costs, which can lead to system imbalances during peak increase demand. In addition, to meet urban and rural electricity demand, a large-scale grid is required, which requires significant investment as well as operation and maintenance costs. For people living in remote areas, these needs become more complex and can lead to power shortages. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art that when the charging function is integrated into electric vehicles, electromagnetic torque and relay failure will occur, the instability of the power grid will increase charging losses, and the scale of the power grid cannot meet the charging needs of a large-scale unidirectional charging system, and to provide a charging device based on a four-phase open-loop coil generator drive system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A charging device based on a four-phase open-loop coil generator drive system, comprising: a motor winding, a power converter, a battery connection device, a three-phase power supply and a battery;

[0008] The motor winding includes a plurality of stator windings which are arranged at equal intervals; the power converter includes a first capacitor Cdc and a plurality of bridge arms connected in parallel with each other; the battery connecting device includes a bridge arm; the bridge arms of the power converter and the battery connecting device are both connected in parallel with the first capacitor Cdc; the bridge arm of the power converter is externally connected to the stator winding; the three-phase power supply is externally connected to the midpoint of the stator winding; and the bridge arm of the battery connecting device is connected to the battery.

[0009] A further improvement of the present invention is:

[0010] Furthermore, the power converter has eight bridge arms and four stator windings, and the four stator windings are arranged at 90-degree intervals; the two ends of the first stator winding are respectively connected to the first bridge arm and the second bridge arm; the two ends of the second stator winding are respectively connected to the third bridge arm and the fourth bridge arm, and the two ends of the third stator winding are respectively connected to the fifth bridge arm and the sixth bridge arm; the two ends of the fourth stator winding are respectively connected to the seventh bridge arm and the eighth bridge arm; the bridge arm of the battery connecting device is the ninth bridge arm, and the ninth bridge arm is connected to the battery.

[0011] Furthermore, the ninth bridge arm is connected to the battery through a ninth inductor and a second capacitor Cb, one end of the ninth inductor is connected to the midpoint of the ninth bridge arm, and the other end of the ninth inductor is connected to one end of the second capacitor Cb and the positive electrode of the battery; the negative electrode of the battery and the other end of the second capacitor Cb are connected to the ninth bridge arm.

[0012] Furthermore, three live wires of the three-phase power supply are respectively connected to the midpoints of the first stator winding, the second stator winding and the third stator winding; and the N wire of the three-phase power supply is connected to the midpoint of the fourth stator winding.

[0013] Furthermore, the first to ninth bridge arms all include an upper bridge arm IGBT switch and a lower bridge arm IGBT switch; the upper bridge arms and lower bridge arms of the first to ninth bridge arms are connected in series, and the upper bridge arms and lower bridge arms all use IGBT switches with anti-parallel diodes.

[0014] Furthermore, the emitter of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the lower bridge arm; the collector of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the upper bridge arm in the next bridge arm; the emitter of the IGBT switch of the lower bridge arm is connected to the emitter of the IGBT switch of the lower bridge arm in the next bridge arm.

[0015] Furthermore, each stator winding includes two branches; each branch includes an inductor and a resistor connected in series; in the driving mode, the two branches are connected in series, and in the charging, V2G and V2H modes, the two branches are connected in parallel; in the charging, V2G and V2H modes, the neutral wire and the live wire of the three-phase power supply are respectively connected between the two inductors in the corresponding stator winding; in the driving mode, the neutral wire and the live wire of the three-phase power supply are not connected to the midpoint of the two inductors in the stator winding.

[0016] Furthermore, there is a socket between the three-phase power supply and the stator winding, which controls the three-phase power supply to supply power to the stator winding.

[0017] Furthermore, in the charging mode, the current provided to the stator winding by the three-phase power supply is twice the current provided to the stator winding by the battery in the driving mode.

[0018] Furthermore, the driving mode is that the three-phase power supply is disconnected from the stator winding, and the battery supplies power to the stator winding through the bridge arm to drive the electric vehicle to move; the charging mode is that the three-phase power supply supplies power to the stator winding, and then charges the electric vehicle; the V2G and V2H modes are that the three-phase power supply is connected to the stator winding, thereby ensuring the V2G and V2H modes, in which the battery sends its energy back to the power grid.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention connects the three-phase power supply to the midpoint of the stator winding in the motor winding, connects the stator winding to the parallel bridge arms in the power converter, and connects the bridge arm of the battery connection device to the battery. The present invention can divide the grid current into two equal parts and flow in opposite directions, thereby achieving a total zero balance of the charging device. The total zero average rotating magnetic field generates zero net electromagnetic torque during charging, thereby keeping the rotor in a stationary position. When the zero line of the three-phase power supply is connected to the center of the stator winding, the present invention can use the two parallel branches of the power converter to control the zero line current to zero, thereby achieving a three-phase balanced system and improving the stability of the grid device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the topological structure of a charging device based on a four-phase open-loop generator drive system of the present invention;

[0023] Figure 2 It is a schematic diagram of the stator winding topology structure of a four-phase open-circuit winding machine in driving mode;

[0024] Figure 3 The schematic diagram of the stator winding topology of a four-phase open-circuit winding machine in charging / V2G / V2H mode;

[0025] Figure 4 A schematic diagram of the switching mode of one phase of a three-phase PWM rectifier in interleaved mode;

[0026] Figure 5 A schematic diagram of the switching mode of one phase of a three-phase PWM rectifier in non-interleaved mode;

[0027] Figure 6 Schematic diagram of the switching mode of the DC-DC converter PWM and the inductor current;

[0028] Figure 7 It is a schematic diagram of the overall topology of charging and V2G mode;

[0029] Figure 8 Schematic diagram of the overall topology of the V2H mode.

[0030] Among them, 1-motor winding; 2-power converter; 3-battery connection device; 4-battery; 5-socket; 6-three-phase power supply; 7-first inductor, 8-second inductor; 9-third inductor; 10-fourth inductor; 11-fifth inductor; 12-sixth inductor; 13-seventh inductor; 14-eighth inductor; 15-first upper bridge arm; 16-first lower bridge arm; 17-second upper bridge arm; 18-second lower bridge arm; 19-third upper bridge arm; 20-third lower bridge arm; 21-fourth upper bridge arm; 22-fourth lower bridge arm; 23-fifth upper bridge arm; 24-fifth lower bridge arm; 25-sixth upper bridge arm; 26-sixth lower bridge arm; 27-seventh upper bridge arm; 28-seventh lower bridge arm; 29-eighth upper bridge arm; 30-eighth lower bridge arm; 31-ninth upper bridge arm; 32-ninth lower bridge arm; 33-first capacitor Cdc; 34-ninth inductor; 35-second capacitor Cb; 37-electric vehicle EV. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0035] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0036] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0038] The present invention discloses a charging device based on a four-phase open-loop coil generator drive system, comprising: a motor winding 1, a power converter 2, a battery connection device 3, a three-phase power supply 6 and a battery 4;

[0039] The motor winding 1 includes a plurality of stator windings, which are arranged at equal intervals; the power converter 2 includes a first capacitor Cdc33 and a plurality of bridge arms connected in parallel; the battery connecting device 3 includes a bridge arm; the bridge arms of the power converter 2 and the battery connecting device 3 are both connected in parallel with the first capacitor Cdc33; the bridge arm of the power converter 2 is externally connected to the stator winding; the three-phase power supply 6 is externally connected to the midpoint of the stator winding; the bridge arm of the battery connecting device 3 is connected to the battery 4.

[0040] The power converter 2 has eight bridge arms and four stator windings, which are arranged at 90-degree intervals; the two ends of the first stator winding are respectively connected to the first bridge arm and the second bridge arm; the two ends of the second stator winding are respectively connected to the third bridge arm and the fourth bridge arm, and the two ends of the third stator winding are respectively connected to the fifth bridge arm and the sixth bridge arm; the two ends of the fourth stator winding are respectively connected to the seventh bridge arm and the eighth bridge arm; the bridge arm of the battery connecting device 3 is the ninth bridge arm, which is connected to the battery 4.

[0041] The ninth bridge arm is connected to the battery 4 through the ninth inductor 34 and the second capacitor Cb35, one end of the ninth inductor 34 is connected to the midpoint of the ninth bridge arm, and the other end of the ninth inductor 34 is connected to one end of the second capacitor Cb35 and the positive electrode of the battery 4; the negative electrode of the battery 4 and the other end of the second capacitor Cb35 are connected to the ninth bridge arm.

[0042] The three live wires of the three-phase power supply 6 are respectively connected to the midpoints of the first stator winding, the second stator winding and the third stator winding; the N wire of the three-phase power supply 6 is connected to the midpoint of the fourth stator winding.

[0043] The first bridge arm to the ninth bridge arm all include an upper bridge arm IGBT switch and a lower bridge arm IGBT switch; the upper bridge arm and the lower bridge arm of the first bridge arm to the ninth bridge arm are connected in series, and the upper bridge arm and the lower bridge arm both use IGBT switches with anti-parallel diodes.

[0044] The emitter of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the lower bridge arm; the collector of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the upper bridge arm in the next bridge arm; the emitter of the IGBT switch of the lower bridge arm is connected to the emitter of the IGBT switch of the lower bridge arm in the next bridge arm.

[0045] The stator winding includes two branches; each branch includes an inductor and a resistor connected in series; in the driving mode, the two branches are connected in series, and in the charging, V2G and V2H modes, the two branches are connected in parallel; in the charging, V2G and V2H modes, the neutral wire and the live wire of the three-phase power supply 6 are respectively connected between the two inductors in the corresponding stator winding; in the driving mode, the neutral wire and the live wire of the three-phase power supply 6 are not connected to the midpoint of the two inductors in the stator winding.

[0046] There is a socket 5 between the three-phase power supply 6 and the stator winding, and the three-phase power supply 6 is controlled to supply power to the stator winding.

[0047] In charging mode, the current provided by the three-phase power supply 6 to the stator winding is twice the current provided by the battery 4 to the stator winding in driving mode. In driving mode, the three-phase power supply 6 is disconnected from the stator winding, and the battery 4 supplies power to the stator winding through the bridge arm to drive the electric vehicle to move; in charging, the three-phase power supply 6 supplies power to the stator winding, thereby charging the electric vehicle; in V2G and V2H modes, the three-phase power supply 6 is connected to the stator winding, thereby ensuring V2G and V2H modes, in which the battery 4 sends its energy back to the grid.

[0048] Example:

[0049] The present invention relates to a charging device based on a four-phase open-circuit winding machine drive system. The device utilizes a four-phase open-circuit winding machine, which can be an induction machine (IM), a permanent magnet synchronous machine (PMSM) or a synchronous reluctance machine (SynRM), as well as a bidirectional eight-leg inverter and a bidirectional DC / DC converter. The charging / V2G / V2H circuit is designed by connecting a three-phase power supply (including the neutral line) to the midpoint of the machine phase.

[0050] The three-phase power conversion (AC to DC) for charging is achieved by controlling six legs of the eight-leg power converter, which acts as an AC voltage source PWM rectifier, while the remaining two legs are used to manage the balanced current sharing between the three-phase system. In vehicle-to-grid (V2G) and vehicle-to-home (V2H) modes, the six-leg power module acts as a voltage source inverter (VSI), thereby supplying power to the three-phase grid or home.

[0051] In electric mode, the three-phase power must first be disconnected from the motor windings through the electric vehicle (EV) charging socket. Then, the eight branches of the power converter are controlled to operate as a VSI to drive the six-phase open-circuit winding motor. The boost and buck voltages when the system operates in all modes (driving, grid to vehicle (G2V) or charging, V2G and V2H) are regulated by a bidirectional DC / DC converter.

[0052] See also Figure 1 The present invention discloses a charging device based on a four-phase open-loop coil motor drive system, comprising: a motor winding 1, a power converter 2, a battery connection device 3, a battery 4 and a three-phase power supply 6;

[0053] The motor winding 1 includes four stator windings, which are arranged at 90 degree intervals; the power converter 2 includes eight bridge arms, and the bridge arms are connected in parallel, the two ends of the first stator winding are respectively connected to the midpoint a1 of the first bridge arm and the midpoint a2 of the second bridge arm; the two ends of the second stator winding are respectively connected to the midpoint b1 of the third bridge arm and the midpoint b2 of the fourth bridge arm; the two ends of the third stator winding are respectively connected to the midpoint c1 of the fifth bridge arm and the midpoint c2 of the sixth bridge arm; the two ends of the fourth stator winding are respectively connected to the midpoint d1 of the seventh bridge arm and the midpoint d2 of the eighth bridge arm; there is a socket 5 between the three-phase power supply 6 and the motor winding 1, which controls the three-phase voltage to supply power to the stator winding.

[0054] The three live wires of the three-phase power supply 6 are connected to the midpoints of the first stator winding, the second stator winding and the third stator winding respectively; the N wire of the three-phase power supply 6 is connected to the midpoint of the fourth stator winding. When the three-phase power supply is connected to the midpoint of the stator winding, the grid current is allowed to be divided into two equal parts and flow in opposite directions, thereby generating two counter-rotating magnetic fields whose sum is zero. The total zero average rotating magnetic field generates zero net electromagnetic torque during charging, which in turn keeps the rotor in a stationary position.

[0055] When the neutral line of the power grid is integrated into the system function, the two parallel branches of the power converter are used to control the neutral line current to zero, realizing a three-phase balanced system. Among them, the neutral line is the zero line.

[0056] The battery connection device 3 includes a ninth bridge arm, a ninth inductor 34 and a second capacitor Cb35; a first capacitor Cdc33 is connected in parallel between the ninth bridge arm and the eighth bridge arm, and the midpoint of the ninth bridge arm is connected to one end of the ninth inductor 34. The other end of the ninth inductor 34 is respectively connected to the positive electrode of the battery 4 and one end of the second capacitor Cb35; the other end of the second capacitor Cb35 and the negative electrode of the battery 4 are connected to the ninth bridge arm.

[0057] The first bridge arm includes a first upper bridge arm 15 and a first lower bridge arm 16, the second bridge arm includes a second upper bridge arm 17 and a second lower bridge arm 18, the third bridge arm includes a third upper bridge arm 19 and a third lower bridge arm 20, the fourth bridge arm includes a fourth upper bridge arm 21 and a fourth lower bridge arm 22, the fifth bridge arm includes a fifth upper bridge arm 23 and a fifth lower bridge arm 24, the sixth bridge arm includes a sixth upper bridge arm 25 and a sixth lower bridge arm 26, the seventh bridge arm includes a seventh upper bridge arm 27 and a seventh lower bridge arm 28, the eighth bridge arm includes an eighth upper bridge arm 29 and an eighth lower bridge arm 30, the ninth bridge arm includes a ninth upper bridge arm 31 and a ninth lower bridge arm 32, the upper bridge arms and the lower bridge arms from the first bridge arm to the ninth bridge arm are connected in series, and the upper bridge arms and the lower bridge arms both use IGBT switches with anti-parallel diodes.

[0058] The emitter of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the lower bridge arm; the collector of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the upper bridge arm in the next bridge arm; the emitter of the IGBT switch of the lower bridge arm is connected to the emitter of the IGBT switch of the lower bridge arm in the next bridge arm.

[0059] Each stator winding includes two branches; each branch includes an inductor and a resistor connected in series; the resistor is connected to one end of the inductor. The midpoint p1 where the first inductor 7 and the second inductor 8 are connected to each other, the midpoint p2 where the third inductor 9 and the fourth inductor 10 are connected to each other, and the midpoint p3 where the fifth inductor 11 and the sixth inductor 12 are connected to each other are respectively connected to the three live wires of the three-phase voltage 6, and the midpoint p4 where the seventh inductor 13 and the eighth inductor 14 are connected to each other is connected to the zero line N of the three-phase voltage 6. In the driving mode, the two branches are connected in series, and in the charging, V2G and V2H modes, the two branches are connected in parallel.

[0060] See also Figure 2 When in the driving mode, the socket 5 between the three-phase power supply 6 and the stator winding is disconnected, and the battery 4 supplies power to the stator winding through the first bridge arm to the ninth bridge arm. The current of the first stator winding is i sa , the current of the second stator winding is i sb , the current of the third stator winding is i sc , the current of the fourth stator winding is i sd .

[0061] See also Figure 3 , when in charging, V2G and V2H modes, the socket 5 between the three-phase power supply 6 and the stator winding is inserted, the three-phase power supply 6 supplies power to the stator winding, and the current of the first stator winding is The current of the second stator winding is The current of the third stator winding is The current of the fourth stator winding is

[0062] The charging power is at least twice as high as the driving power, because the current flowing through the stator winding during charging is twice as high as in driving mode.

[0063] In drive mode, the current flowing through the stator winding is I s , which comes from the battery. In charging mode, the current flowing through each branch of the parallel stator winding is I g / 2, this current comes from the power grid.

[0064] If the expression of grid current is replaced by stator winding current and two parallel branches are considered, we get: I g =2I sThis means that the power in charging mode is at least twice as high as in driving mode.

[0065] Among them, the power in charging mode is:

[0066]

[0067] The power in driving mode is:

[0068]

[0069] By rearranging the equation, we get:

[0070] P chg =2(V g / V s )(PF / PF′)P drive .

[0071] Generally speaking, and P chg ≥2P drive .

[0072] Where Vg is the grid voltage, Vs is the stator winding voltage (or the motor back EMF in drive mode), PF is the power factor in charge mode, and PF' is the power factor in drive mode.

[0073] See also Figure 4 , shows the single-phase switching pattern of the PWM three-phase rectifier operating in interleaved mode in charging, vehicle-to-grid (V2G) and vehicle-to-home (V2H) modes. The two carrier signals Vsaw1 and Vsaw2 are 180 degrees out of phase with each other. The reference voltage Vrefp (which can correspond to phase A, phase B or phase C) is compared with Vsaw1 and Vsaw2 to generate reference PWM1 and PWM2 waveforms, and the switching states of these PWM signals describe the stator current ripple (Ispp1 and Ispp2) and the grid current ripple (Igpp). Figure 4 It is shown that the ripple on the grid side is significantly reduced when operating in interleaved mode.

[0074] Figure 5 Figure 2 shows the switching pattern of a single-phase PWM rectifier in three-phase operation (without interleaving mode). In this mode, the two carrier signals Vsaw1 and Vsaw2 are in the same phase and have the same amplitude, so the ripple currents of the stator winding and the grid are the same. Figure 6 The switching pattern of the DC-DC converter PWM signal and the inductor current is shown. The reference voltage VrefL is compared with the carrier signal Vsaw3 to generate the output reference PWM3, which determines the ripple waveform (ILpp) of the DC-DC converter current iL. Figure 7 and Figure 8 The overall topology of charging, V2G and V2H modes is shown.

[0075] In the charging / V2G mode, the electric vehicle EV37 is connected to the grid 6 via the charging / V2G socket 5. In the V2H mode, the electric vehicle EV37 is connected to the household socket via the socket 5.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A charging device based on a four-phase open-loop generator drive system, characterized in that: include: Motor winding (1), power converter (2), battery connection device (3), three-phase power supply (6) and battery (4); The motor winding (1) comprises a plurality of stator windings, which are arranged at equal intervals; the power converter (2) comprises a first capacitor Cdc (33) and a plurality of bridge arms connected in parallel; the battery connection device (3) comprises a bridge arm; the bridge arms of the power converter (2) and the battery connection device (3) are both connected in parallel with the first capacitor Cdc (33); the bridge arm of the power converter (2) is externally connected to the stator winding; the three-phase power supply (6) is externally connected to the midpoint of the stator winding; and the bridge arm of the battery connection device (3) is connected to a battery (4).

2. The charging device based on the four-phase open-loop generator drive system according to claim 1 is characterized in that: The power converter (2) has eight bridge arms, and four stator windings, which are arranged at 90-degree intervals; the two ends of the first stator winding are respectively connected to the first bridge arm and the second bridge arm; the two ends of the second stator winding are respectively connected to the third bridge arm and the fourth bridge arm, and the two ends of the third stator winding are respectively connected to the fifth bridge arm and the sixth bridge arm; the two ends of the fourth stator winding are respectively connected to the seventh bridge arm and the eighth bridge arm; the bridge arm of the battery connection device (3) is the ninth bridge arm, and the ninth bridge arm is connected to the battery (4).

3. The charging device based on the four-phase open-loop generator drive system according to claim 2 is characterized in that: The ninth bridge arm is connected to the battery (4) via a ninth inductor (34) and a second capacitor Cb (35); one end of the ninth inductor (34) is connected to the midpoint of the ninth bridge arm, and the other end of the ninth inductor (34) is connected to one end of the second capacitor Cb (35) and the positive electrode of the battery (4); the negative electrode of the battery (4) and the other end of the second capacitor Cb (35) are connected to the ninth bridge arm.

4. The charging device based on the four-phase open-loop generator drive system according to claim 3 is characterized in that: The three live wires of the three-phase power supply (6) are respectively connected to the midpoints of the first stator winding, the second stator winding and the third stator winding; and the N wire of the three-phase power supply (6) is connected to the midpoint of the fourth stator winding.

5. The charging device based on the four-phase open-loop winding machine drive system according to claim 4 is characterized in that: The first to ninth bridge arms all include an upper bridge arm IGBT switch and a lower bridge arm IGBT switch; the upper bridge arms and lower bridge arms of the first to ninth bridge arms are connected in series, and the upper bridge arms and lower bridge arms all use IGBT switches with anti-parallel diodes.

6. The charging device based on the four-phase open-loop winding machine drive system according to claim 5 is characterized in that: The emitter of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the lower bridge arm; the collector of the IGBT switch of the upper bridge arm is connected to the collector of the IGBT switch of the upper bridge arm in the next bridge arm; the emitter of the IGBT switch of the lower bridge arm is connected to the emitter of the IGBT switch of the lower bridge arm in the next bridge arm.

7. The charging device based on the four-phase open-loop generator drive system according to claim 6 is characterized in that: The stator windings each include two branches; each branch includes an inductor and a resistor connected in series; in the driving mode, the two branches are connected in series, and in the charging, V2G and V2H modes, the two branches are connected in parallel; in the charging, V2G and V2H modes, the neutral line and the live line of the three-phase power supply (6) are respectively connected between the two inductors in the corresponding stator windings; in the driving mode, the neutral line and the live line of the three-phase power supply (6) are not connected to the midpoints of the two inductors in the stator windings.

8. The charging device based on the four-phase open-loop generator drive system according to claim 7 is characterized in that: A socket (5) is provided between the three-phase power supply (6) and the stator winding, and the three-phase power supply (6) is controlled to supply power to the stator winding.

9. The charging device based on the four-phase open-loop generator drive system according to claim 8, characterized in that: In the charging mode, the current provided by the three-phase power supply (6) to the stator winding is twice the current provided by the battery (4) to the stator winding in the driving mode.

10. The charging device based on the four-phase open-loop generator drive system according to claim 9, characterized in that: The driving mode is that the three-phase power supply (6) is disconnected from the stator winding, and the battery (4) supplies power to the stator winding through the bridge arm to drive the electric vehicle to move; the charging mode is that the three-phase power supply (6) supplies power to the stator winding, thereby charging the electric vehicle; the V2G and V2H modes are that the three-phase power supply (6) is connected to the stator winding, thereby ensuring the V2G and V2H modes, in which the battery (4) sends its energy back to the power grid.

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