Single-stage isolated bidirectional on-board integrated charging system for new energy vehicles

Abstract

This invention relates to a single-stage isolated bidirectional on-board integrated charging system for new energy vehicles, belonging to the field of on-board integrated charging. It addresses the problems of large size, high cost, and high losses in existing two-stage isolated on-board charging systems. The invention proposes a single-stage isolated bidirectional AC-DC charging and discharging topology based on the reconfiguration of three-phase motor windings. Compared to existing two-stage topologies, this topology further reduces size, cost, and losses, improving system efficiency. This single-stage isolated bidirectional AC-DC charging and discharging topology also increases the value of the equivalent filter inductance on the grid side during charging and discharging. Since the motor does not rotate during charging, it can suppress harmonics in the grid-side current, reducing costs and further decreasing internal losses within the motor. This invention is primarily applied to charging new energy vehicles.

Description

Technical Field

[0001] This invention belongs to the field of vehicle-mounted integrated charging. Background Technology

[0002] For isolated integrated charging systems that reuse a three-phase permanent magnet synchronous motor and its associated drive inverter as the corresponding grid-side filter inductor and power converter in charging mode, existing topologies employ traditional structures such as PFC+DAB or PFC+CLLC. This is equivalent to a two-stage AC-DC converter followed by a series-connected isolated DC-DC converter. This two-stage charging system has a complex structure and numerous switching devices, resulting in large size, high cost, and high losses. Furthermore, for the PFC stage, existing technology injects zero-sequence current into the three windings in charging mode to prevent the motor from rotating during charging. In this zero-sequence current torque elimination method, the winding inductor acting as the grid-side filter in charging mode is the motor's winding leakage inductance. Moreover, for a three-parallel inverter system, under single-phase and DC input power conditions, the equivalent grid-side filter inductance is approximately one-third the value of a single winding leakage inductance. An excessively low equivalent grid-side inductance will reduce the power quality injected into the grid, manifested as an increase in harmonics in the grid-side current. At the same time, excessive current harmonics will aggravate the losses of switching devices such as motors and inverters. These problems need to be addressed. Summary of the Invention

[0003] The purpose of this invention is to solve the problems of large size, high cost and high loss in existing two-stage isolated on-board charging systems. This invention provides a single-stage isolated bidirectional on-board integrated charging system for new energy vehicles.

[0004] A single-stage isolated bidirectional on-board integrated charging system for new energy vehicles includes the original on-board drive system and clamping capacitor C. c A single-stage isolated bidirectional AC-DC charging and discharging topology, constructed from a switching switch, a high-frequency transformer, and a full-bridge converter, is used to charge or discharge the vehicle battery.

[0005] In charge / discharge mode, a switching switch is used to change the connection method of the three-phase windings of the original vehicle drive system's three-phase motor. The three-phase windings of the original vehicle drive system's three-phase motor are reused as PFC inductors, and the original vehicle drive system's three-phase inverter is reused as an AC-AC converter. After converting the single-phase power supply's mains frequency AC power into high-frequency AC power, it is then connected to a clamping capacitor C. c The voltage is fed to a high-frequency transformer, where it is transformed and then rectified by a full-bridge converter. It then passes through the bus capacitor C of the original vehicle drive system. bat After voltage stabilization, the vehicle battery is charged.

[0006] Preferably, the changeover switch includes single-pole single-control switches K1 and K2.31 and K 32 and single-opening dual-control K 21 and K 22 ;

[0007] The input terminals of the a, b, and c phase windings of the three-phase motor are connected to one end of switch K1 and the second and third AC output terminals of the three-phase inverter, respectively. The other end of switch K1 is connected to the first AC output terminal of the three-phase inverter. The first and second AC output terminals of the three-phase inverter are also connected to a single-pole single-control switch K1. 31 and K 32 One end is connected to a single-pole single-control switch K. 31 and K 32 The other end is connected to one end and the other end of the primary winding of the high-frequency transformer, respectively;

[0008] The two ends of the secondary winding of the high-frequency transformer are connected to the two single-phase AC terminals of the full-bridge converter, and the two DC terminals of the full-bridge converter are respectively used as single-phase double-controlled K-phase converters. 21 and K 22 The second option;

[0009] The first DC input terminal of the three-phase inverter and the clamping capacitor C c One end and single-opening dual-control K 21 The first selection terminal is connected simultaneously, and the second DC input terminal of the three-phase inverter is connected to the clamping capacitor C. c The other end and single-opening dual-control K 22 The first selection terminal is connected simultaneously, and the bus capacitor C bat The two ends connected in parallel with the battery are respectively connected to a single-pole dual-controller K. 21 and K 22 Fixed end connection;

[0010] In drive mode, single-pole single-control switch K1 is closed, and single-pole double-control switch K1 is closed. 21 and K 22 All switches are switched to the first selection terminal, single-pole single-control switch K. 31 and K 32 It is in the disconnected state;

[0011] In charging mode, the two ends of the single-pole single-control switch K1 are used to connect to the two charging terminals P of the single-phase power supply, respectively. g1 and P g2 The connection is established, and the single-pole single-control switch K1 is in the off state, while the single-pole double-control switch K1 is in the off state. 21 and K 22 All switches are switched to the second selection terminal, single-pole single-control switch K. 31 and K 32 It is in a closed state.

[0012] Preferably, the three-phase inverter is a three-phase full-bridge inverter, and the first, second and third AC output terminals of the three-phase inverter are the midpoints of the a, b and c phase half-bridges of the three-phase inverter, respectively.

[0013] The a-phase half-bridge of the three-phase inverter consists of power switches S3 and S4 located above and below, the b-phase half-bridge consists of power switches S5 and S6 located above and below, and the c-phase half-bridge consists of power switches S1 and S2 located above and below.

[0014] In charging and discharging mode, power switches S1 and S2 are alternately turned on at the grid frequency of 50Hz, power switches S3 and S4 are alternately turned on with a 50% duty cycle, and power switches S5 and S6 are alternately turned on with a 50% duty cycle; and

[0015] When the grid-side voltage Vg is greater than 0, power switch S1 is turned off and power switch S2 is turned on. When the grid-side voltage Vg is less than or equal to 0, power switch S1 is turned on and power switch S2 is turned off. Here, the grid-side voltage Vg is the power frequency AC output of the single-phase power supply.

[0016] Preferably, the clamping capacitor C c Voltage V across the terminals Cc It is twice the grid-side voltage Vg, where the grid-side voltage Vg is the power frequency AC output of a single-phase power supply.

[0017] Preferably, the high-frequency transformer is implemented using a single-phase half-bridge inverter, and the carrier waves of the two switching transistors in each of the two branches of the single-phase half-bridge inverter are phase-shifted by 180°, and both are modulated using the signal d(t), where d(t) = k|sin(ωt). g t)|;k is a coefficient, and k∈[0,0.5], ω g Let t be the angular frequency of the power grid, and t be time.

[0018] Preferably, the equivalent filter inductance L of phases a, b, and c of the PFC inductor is... eqa L eqb and L eqc They are respectively:

[0019]

[0020] Among them, L σs For the self-leakage inductance of the motor winding, L m L is the mutual leakage inductance between the motor windings, and L is the average value of the self-inductance of the motor windings. Δ1 θ represents the amplitude of the second harmonic of the self-inductance of the motor winding, and θ is the rotor position angle.

[0021] Advantages of this invention:

[0022] This invention proposes a single-stage isolated bidirectional AC-DC charging and discharging topology based on the reconfiguration of three-phase motor windings. Compared with the existing two-stage topology, this topology further reduces volume, cost, and losses, improving system efficiency. This single-stage isolated bidirectional AC-DC charging and discharging topology can also increase the value of the grid-side equivalent filter inductance during charging and discharging. Since the motor does not rotate during charging, it can suppress harmonics of the grid-side current, reducing costs while further reducing internal losses of the motor and further improving system efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the single-stage isolated bidirectional on-board integrated charging system for new energy vehicles described in this invention; wherein, L s The leakage inductance of the primary winding of a high-frequency transformer;

[0024] Figure 2 This is the equivalent circuit diagram of the vehicle-mounted integrated charging system of the present invention in driving mode;

[0025] Figure 3 This is the equivalent circuit diagram of the vehicle-mounted integrated charging system of the present invention in charging mode.

[0026] Figure 4 This diagram shows the switching status and voltage waveforms on the primary side of a high-frequency transformer; where S... 1，4 Indicates power switching transistors S1 and S4, S 2,3 Indicates power switching transistors S2 and S3, V g,peak Indicates grid-side voltage V g Peak voltage, V a,b Table 1 shows the voltage between the midpoint a of phase a bridge arm and the midpoint b of phase b bridge arm in a three-phase inverter, in V. Cc Indicates the clamping capacitor C c The voltage across the two ends;

[0027] Figure 5 The diagram shows the switching status and voltage waveforms on the secondary side of the high-frequency transformer; among them, For the carrier wave of switch S9, For the carrier wave of switch S7, V cd V is the voltage between the midpoints c and d of the two bridge arms of the full-bridge converter. bat Battery voltage;

[0028] Figure 6 The simulation waveforms are shown in G2V mode; among them, Figure 6 a is the input voltage and current waveform diagram of the single-phase power supply to the three-phase motor in G2V mode; Figure 6 b shows the waveforms of the clamping capacitor voltage and battery current. Figure 6 c shows the current waveforms of phases a and b of the three-phase motor; Figure 6 d is a pair Figure 6 c. The waveform after magnification;

[0029] Figure 7 The simulation waveforms are shown in V2G mode; among them, Figure 7 a is the input voltage and current waveform diagram from the single-phase power supply to the three-phase motor in V2G mode; Figure 7 b shows the waveforms of the clamping capacitor voltage and battery current. Figure 7 c shows the current waveforms of phases a and b of the three-phase motor; Figure 7 d is a pair Figure 7 c. The waveform after magnification;

[0030] Figure 8 The simulation results of the motor torque under single-phase AC charging are shown in the figure. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0033] Combination Figure 1 This embodiment describes a single-stage isolated bidirectional on-board integrated charging system for new energy vehicles, comprising the original on-board drive system and a clamping capacitor C. c A single-stage isolated bidirectional AC-DC charging and discharging topology is constructed using a switching switch, a high-frequency transformer, and a full-bridge converter to charge or discharge the vehicle battery.

[0034] In charge / discharge mode, a switching switch is used to change the connection method of the three-phase windings of the original vehicle drive system's three-phase motor. The three-phase windings of the original vehicle drive system's three-phase motor are reused as PFC inductors, and the original vehicle drive system's three-phase inverter is reused as an AC-AC converter. After converting the single-phase power supply's mains frequency AC power into high-frequency AC power, it is then connected to a clamping capacitor C. c The voltage is fed to a high-frequency transformer, where it is transformed and then rectified by a full-bridge converter. It then passes through the bus capacitor C of the original vehicle drive system. bat After voltage stabilization, the vehicle battery is charged.

[0035] In practical applications, a high-frequency transformer typically refers to a transformer with a frequency higher than 20kHz. In practical applications, the turns ratio of its primary and secondary sides can be n:1, where n is an integer.

[0036] The single-stage isolated bidirectional AC-DC charging and discharging topology constructed in this embodiment further reduces volume, cost, and losses compared to the existing two-stage topology, thereby improving system efficiency.

[0037] Further, see Figure 1 The switching switches include single-pole single-control switches K1 and K2. 31 and K 32 and single-opening dual-control K 21 and K 22 ;

[0038] The input terminals of the a, b, and c phase windings of the three-phase motor are connected to one end of switch K1 and the second and third AC output terminals of the three-phase inverter, respectively. The other end of switch K1 is connected to the first AC output terminal of the three-phase inverter. The first and second AC output terminals of the three-phase inverter are also connected to a single-pole single-control switch K1. 31 and K 32 One end is connected to a single-pole single-control switch K. 31 and K 32 The other end is connected to one end and the other end of the primary winding of the high-frequency transformer, respectively;

[0039] The two ends of the secondary winding of the high-frequency transformer are connected to the two single-phase AC terminals of the full-bridge converter, and the two DC terminals of the full-bridge converter are respectively used as single-phase double-controlled K-phase converters. 21 and K 22 The second option;

[0040] The first DC input terminal of the three-phase inverter and the clamping capacitor C c One end and single-opening dual-control K 21 The first selection terminal is connected simultaneously, and the second DC input terminal of the three-phase inverter is connected to the clamping capacitor C. c The other end and single-opening dual-control K 22 The first selected end is connected simultaneously;

[0041] Bus capacitor C bat The two ends connected in parallel with the battery are respectively connected to a single-pole dual-controller K. 21 and K 22 Fixed end connection;

[0042] See Figure 2 In drive mode, single-pole single-control switch K1 is closed, and single-pole double-control switch K1 is closed. 21 and K 22 All switches are switched to the first selection terminal, single-pole single-control switch K. 31 and K 32It is in the disconnected state;

[0043] See Figure 3 In charging mode, the two ends of the single-pole single-control switch K1 are used to connect to the two charging terminals P of the single-phase power supply, respectively. g1 and P g2 The connection is established, and the single-pole single-control switch K1 is in the off state, while the single-pole double-control switch K1 is in the off state. 21 and K 22 All switches are switched to the second selection terminal, single-pole single-control switch K. 31 and K 32 It is in a closed state. During actual charging, energy is drawn from the charging gun, which is a single-phase power source on the AC charging pile, through the motor windings. After the three-phase inverter effectively controls the power frequency AC output and the single-phase power output current, the energy is transferred to the high-frequency transformer and the full-bridge converter. The full-bridge converter provides a wide range of voltage regulation capabilities, ensuring that the input energy is smoothly and safely delivered to the battery.

[0044] This preferred embodiment provides a specific structure of a single-stage isolated bidirectional AC-DC charging and discharging topology. By using a switching switch to change the winding connection method, the working mode of the integrated charging system can be realized. Furthermore, this single-stage isolated bidirectional AC-DC charging and discharging topology can also improve the value of the grid-side equivalent filter inductance in the charging and discharging mode. During the charging process, the motor does not rotate, which can suppress the harmonics of the grid-side current, reduce costs, further reduce the internal losses of the motor, and further improve the efficiency of the system.

[0045] Furthermore, the three-phase inverter is a three-phase full-bridge inverter, and the first, second, and third AC output terminals of the three-phase inverter are the midpoints of the a, b, and c phase half-bridges of the three-phase inverter, respectively.

[0046] The a-phase half-bridge of the three-phase inverter consists of power switches S3 and S4 located above and below, the b-phase half-bridge consists of power switches S5 and S6 located above and below, and the c-phase half-bridge consists of power switches S1 and S2 located above and below.

[0047] In charging and discharging mode, power switches S1 and S2 are alternately turned on at the grid frequency of 50Hz, power switches S3 and S4 are alternately turned on with a 50% duty cycle, and power switches S5 and S6 are alternately turned on with a 50% duty cycle; and

[0048] When the grid-side voltage Vg is greater than 0, power switch S1 is turned off and power switch S2 is turned on. When the grid-side voltage Vg is less than or equal to 0, power switch S1 is turned on and power switch S2 is turned off. Here, the grid-side voltage Vg is the power frequency AC output of the single-phase power supply.

[0049] Therefore, regardless of the power level, the clamping capacitor C cVoltage V across the terminals Cc Both are twice the grid-side voltage Vg, where Vg is the power frequency AC output from a single-phase power supply. The power switching states and voltage waveforms on the primary side of the high-frequency transformer are as follows: Figure 4 As shown. Figure 4 This demonstrates that switches S1 and S4 have the same driving waveform, and switches S2 and S3 also have the same driving waveform, complementing those of switches S1 and S4. Clamp capacitor voltage V Cc The voltage waveform has a peak value of 2V. g,peak The waveform of a steamed bun. The input voltage V on the primary side of the transformer. ab It is related to the operating state of the switching transistors. When switching transistors S1 and S4 are turned on, V ab For V Cc When switches S2 and S3 are turned on, V ab -V Cc .

[0050] See further Figure 5 The high-frequency transformer is implemented using a single-phase half-bridge inverter. In the two branches of the single-phase half-bridge inverter, the carrier waves of the two switching transistors in each branch are phase-shifted by 180° and modulated using the signal d(t).

[0051] d(t)=k|sin(ω g t)| (1);

[0052] Where k is a coefficient, and k∈[0,0.5], ω g Let t be the angular frequency of the power grid, and t be time.

[0053] Figure 5 Given the carrier of carrier switch S7 With the carrier of switch S9 When the phase difference is 180 degrees, the modulating wave d(t) is greater than the carrier wave. When the switching transistor S9 is turned on; when the modulated wave d(t) is greater than the carrier wave... When switching transistor S7 is turned on. Switching transistors S8 and S7 are complementary in their conduction. 10 It is complementary to the conduction of switch S9. When switch S7 and switch S... 10 Simultaneously, the transformer secondary voltage V is turned on. cd Load voltage V bat When both switching transistors S8 and S9 are turned on, the secondary voltage V of the transformer... cd -V bat In other cases, V cd It is 0.

[0054] Furthermore, the inductance of the motor winding reconstructed into a grid-side filter inductor is analyzed. The reconstructed grid-side filter inductor is a PFC inductor. The specific analysis process is as follows:

[0055] For a three-phase motor, the expressions for its winding self-inductance and mutual inductance are as follows:

[0056]

[0057]

[0058] Among them, L σs For the self-leakage inductance of the motor windings, the values ​​of each phase winding in a three-phase motor are equal, L m L represents the mutual leakage inductance between motor windings, primarily the slot leakage inductance. L is the average value of the self-inductance of the motor windings. Δ1 θ represents the amplitude of the second harmonic of the self-inductance of the motor winding, and θ is the rotor position angle.

[0059] The inductance matrix of a three-phase winding motor is represented as follows:

[0060]

[0061] The motor winding current in charging mode can be expressed as:

[0062] i s =[i sa i sb i sc ] T (7);

[0063] Stator winding flux linkage ψ along the abc phase axis of the motor sm m = a, b, c can be determined by the equivalent inductance L of the motor windings. eqm and rotor permanent magnet flux linkage ψ fm Indicate:

[0064]

[0065] Using the stator inductance matrix L ss The magnetic flux represented by the second term in the above equation Expand:

[0066] ψ ss =L ss i s (9);

[0067] Therefore, the equivalent inductance L of the motor winding eqss It can be represented as:

[0068] L eqss =[L eqa ,L eqb ,Leqc ] T =ψ ss . / i s (10);

[0069] In the formula, ψ ss —Stator flux linkage generated by the excitation of the motor winding current;

[0070] . / — This represents the division operator for corresponding elements in a matrix.

[0071] according to Figure 3 If the absolute value of the current flowing through phase c is twice that of phases a and b, then we can obtain:

[0072] i sc =-2i sa =-2i sb =I m cos(ω g t) (11);

[0073] Among them, I m This represents the peak value of the grid-side current.

[0074] Substituting Equation 11 into Equation 10, the equivalent filter inductance can be calculated using the inductance matrix above:

[0075] The equivalent filter inductance L of phases a, b, and c of the PFC inductor eqa L eqb and L eqc They are respectively:

[0076]

[0077] Therefore, it can be seen that the equivalent inductance at this time includes the self-inductance of the winding. Thus, compared with the case of zero-sequence current injection, the equivalent inductance has been greatly improved, which is beneficial to reduce grid-side current harmonics and improve system charging efficiency.

[0078] Verification experiment:

[0079] The technical effects of the present invention are illustrated through the following verification experiments:

[0080] Simulation results are presented for both charging mode (G2V mode) and discharging mode (V2G mode). In G2V mode, the input voltage and current, as well as the clamping capacitor voltage and battery current waveforms, are shown below. Figure 6 As shown. Specifically Figure 6 In step a, the input current and input voltage are in phase, verifying that the topology and control method can realize the PFC function; Figure 6 b verified that the clamping capacitor voltage is a steampuff wave with a peak value equal to the peak value of the grid-side voltage V. g，peakThe battery current is twice that of the battery in G2V mode, and the battery current is positive, meaning the battery is in a charging state. Figure 6 c reflects that the magnitude and phase of the current in phase a and phase b are not exactly the same in G2V mode. This is because the equivalent impedances of phase a and phase b are not exactly the same. Figure 6 d reflects that the phase a current waveform and the phase b current waveform are 180 degrees out of phase at high frequency under G2V mode, which verifies the accuracy of the control method.

[0081] In V2G mode, the input voltage and current, as well as the clamp capacitor voltage and battery current waveforms are as follows: Figure 7 As shown, the specific Figure 7 In step a, the input current and input voltage are in opposite directions, i.e., the power factor is -1, which verifies that this topology and control method can realize V2G function; Figure 7 b verified that the clamping capacitor voltage is a steampuff wave with a peak value equal to the peak value of the grid-side voltage V. g，peak The current is twice that of the battery, and the battery current is negative in V2G mode, meaning the battery is in a discharging state. Figure 7 c reflects that the magnitude and phase of the current in phase a and phase b are not exactly the same in V2G mode. This is because the equivalent impedances of phase a and phase b are not exactly the same. Figure 7 d reflects that the current waveforms of phase a and phase b in V2G mode are 180 degrees out of phase at high frequency, which verifies the accuracy of the control method.

[0082] The simulation results of torque based on this integrated topology are also given at a charging power of 6.6kW, such as... Figure 8 As shown, the average torque of the motor in charging mode is essentially zero, and the motor does not rotate, verifying the effectiveness of the invention.

[0083] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A single-stage isolated bidirectional on-board integrated charging system for new energy vehicles, characterized in that, This includes the original vehicle drive system and clamping capacitors. A single-stage isolated bidirectional AC-DC charging and discharging topology, constructed from a switching switch, a high-frequency transformer, and a full-bridge converter, is used to charge or discharge the vehicle battery. In charge / discharge mode, a switching switch is used to change the connection method of the three-phase windings of the original vehicle drive system's three-phase motor. The three-phase windings of the original vehicle drive system's three-phase motor are reused as PFC inductors, and the original vehicle drive system's three-phase inverter is reused as an AC-AC converter. After converting the single-phase power supply's mains frequency AC power into high-frequency AC power, it is then connected via a clamping capacitor. The voltage is fed to a high-frequency transformer, where it is transformed and then rectified by a full-bridge converter. It then passes through the bus capacitor of the original vehicle drive system. After voltage stabilization, the vehicle battery is charged; Changeover switches include single-pole single-throw switches , and and single-opening dual-control and ; The input terminals of the a, b, and c phase windings of the three-phase motor are respectively connected to the switch. Connect one end of the switch to the second and third AC output terminals of the three-phase inverter. The other end is connected to the first AC output terminal of the three-phase inverter; the first and second AC output terminals of the three-phase inverter are also connected to a single-pole single-control switch respectively. and One end is connected to a single-pole single-control switch. and The other end is connected to one end and the other end of the primary winding of the high-frequency transformer, respectively; The two ends of the secondary winding of the high-frequency transformer are connected to the two single-phase AC terminals of the full-bridge converter, and the two DC terminals of the full-bridge converter are used as single-phase double-controlled terminals. and The second option; The first DC input terminal of the three-phase inverter and the clamping capacitor One end and single-opening dual-control The first selection terminal is simultaneously connected, and the second DC input terminal of the three-phase inverter is connected to the clamping capacitor. The other end and single-opening dual-control The first selection terminal is connected simultaneously, and the bus capacitor is also connected. The two ends connected in parallel with the battery are respectively connected to a single-pole dual-controller. and Fixed end connection; In drive mode, single-pole single-control switch In closed state, single-open double-control and All switches are switched to the first selection terminal, single-pole single-control switch. and It is in the disconnected state; In charging mode, single-pole single-control switch The two ends are used to connect to the two charging terminals P of a single-phase power supply, respectively. g1 and P g2 Connection, and single-pole single-control switch In the disconnected state, single-pole dual-controller and All switches are switched to the second selection terminal, single-pole single-control switch. and It is in a closed state.

2. The single-stage isolated bidirectional on-board integrated charging system for new energy vehicles according to claim 1, characterized in that, The three-phase inverter is a three-phase full-bridge inverter, and the first, second and third AC output terminals of the three-phase inverter are the midpoints of the a, b and c phase half-bridges of the three-phase inverter, respectively. The a-phase half-bridge of the three-phase inverter consists of power switches S3 and S4 located above and below, the b-phase half-bridge consists of power switches S5 and S6 located above and below, and the c-phase half-bridge consists of power switches S1 and S2 located above and below. In charging and discharging mode, power switches S1 and S2 are alternately turned on at the grid frequency of 50Hz, power switches S3 and S4 are alternately turned on with a 50% duty cycle, and power switches S5 and S6 are alternately turned on with a 50% duty cycle; and When the grid-side voltage Vg is greater than 0, power switch S1 is turned off and power switch S2 is turned on. When the grid-side voltage Vg is less than or equal to 0, power switch S1 is turned on and power switch S2 is turned off. Here, the grid-side voltage Vg is the power frequency AC output of the single-phase power supply.

3. The single-stage isolated bidirectional on-board integrated charging system for new energy vehicles according to claim 1, characterized in that, Clamping capacitor Voltage V across the terminals Cc It is twice the grid-side voltage Vg, where the grid-side voltage Vg is the power frequency AC output of a single-phase power supply.

4. The single-stage isolated bidirectional on-board integrated charging system for new energy vehicles according to claim 1, characterized in that, The high-frequency transformer is implemented using a single-phase half-bridge inverter. In the two branches of the single-phase half-bridge inverter, the carrier waves of the two switching transistors in each branch are phase-shifted by 180°, and both use signal... Modulation is performed, in which... Let be the coefficient, and , The angular frequency of the power grid. For time.

5. The single-stage isolated bidirectional on-board integrated charging system for new energy vehicles according to claim 1, characterized in that, Equivalent filter inductance of phases a, b, and c of the PFC inductor , and They are respectively: ； ； ； in, This refers to the self-leakage inductance of the motor windings. This refers to the mutual leakage inductance between the motor windings. This represents the average value of the self-inductance of the motor windings. This represents the amplitude of the second harmonic of the self-inductance of the motor winding. This is the rotor position angle.

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