An electric vehicle boost charging circuit and method

Abstract

The application provides an electric vehicle boosting charging circuit and method, a motor coil module includes three motor coils, a switch module is connected with the motor coil module, and the working mode of the motor coil module is controlled through the switch module; when the working mode is a charging and discharging mode, a power battery, a power module, the motor coil module, a charging starting buffer module, the switch module and a direct current charging port form four different charging and discharging circuits in sequence; in the charging and discharging circuit, the three motor coils are connected in series in the four charging and discharging circuits, so that the current flowing through the three motor coils is equal. The application switches the traditional "star motor" connection mode to series connection through the switch module, so that the current flowing into the motor coil is consistent in size and direction in the charging and discharging circuit, thereby reducing the output torque, improving the comfort of the vehicle used by the customer, increasing the storage of the equivalent inductance, eliminating the current ripples generated in the charging process, and prolonging the service life of other electronic devices.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, specifically to a boost charging circuit and method for electric vehicles. Background Technology

[0002] Power performance and driving range are key indicators for electric vehicles and are also factors that consumers consider when choosing a car. To achieve better power performance and longer driving range, high-voltage power batteries have received widespread attention. Currently, existing boost technology can directly charge high-voltage power batteries through low-voltage DC charging ports, solving the problem that low-voltage DC charging stations cannot charge high-voltage power batteries. However, in related technologies, the three-phase coils of the motor and power modules are often reused to charge the power battery. During charging, the current output of the motor coils becomes unbalanced, generating torque that causes vehicle vibration and affects the customer experience. Furthermore, if the equivalent inductance of the motor is low, large current ripples will be generated during charging, increasing the risk of damage to other electronic components.

[0003] Therefore, designing a simple and balanced boost charging circuit for the motor's three-phase current is a technical problem that urgently needs to be solved.

[0004] Prior art document 1 (CN216851386U) provides charging current and a vehicle, and a charging circuit including a boost circuit, a three-phase motor coil, and a three-phase inverter connected in sequence, wherein: the first and second terminals of the boost circuit are respectively connected to the first and second terminals of the charging port of an electric vehicle; the third terminal of the boost circuit is connected to the connection point of the three-phase coil of the three-phase motor coil; the fourth terminal of the boost circuit is connected to the second terminal of the three-phase inverter; the three-phase coil of the three-phase motor coil is respectively connected to the midpoint of the three-phase bridge arm of the three-phase inverter; and the first and second terminals of the three-phase inverter are respectively connected to the positive and negative terminals of the power battery. This circuit achieves charging of the high-voltage power battery through the parallel connection of the three-phase motor coils via the low-voltage DC charging port, but the equivalent inductance of the circuit structure is low, which will generate current ripple and affect the lifespan of other electronic components.

[0005] Prior art document 2 (CN112440761A) provides a drive motor system, a control method for the drive motor system, and an electric vehicle. The system includes: a first switch, a drive motor, and a drive motor control circuit. The first switch is connected to a DC charging port and the midpoint of the first bridge arm in the drive motor control circuit, respectively. When the first switch is closed, the second switch of the power battery circuit is closed, and the third switch between the DC charging port and the drive motor control circuit is open, the DC charging port is connected to the midpoint of the first bridge arm, so that the winding inductance in the drive motor and the drive motor control circuit form a boost circuit or a buck circuit. The power battery is charged by connecting two phase inductors in parallel and the third phase inductor in series. However, during the charging process, the unbalanced current flowing through the inductors generates torque, which affects the customer experience. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the present invention provides a boost charging circuit and method for electric vehicles to solve the above-mentioned technical problems.

[0007] To achieve the above and other related objectives, the technical solution provided by this invention is as follows.

[0008] This invention provides a boost charging circuit for electric vehicles, used to balance the current flowing into the motor coil in the boost charging circuit. It is characterized by comprising a power module, a motor coil module, a charging start-up buffer module, and a switch module. The power module is connected to the motor coil module and the charging start-up buffer module respectively. The power module is also connected to a power battery, and the charging start-up buffer module is also connected to a DC charging port.

[0009] The motor coil module includes three motor coils. The switch module is connected to the motor coil module and is used to switch the operating mode of the motor coil module. The operating mode of the motor coil module includes a charging and discharging mode. When the switch module switches the motor coil module to the charging and discharging mode, the power battery, the power module, the motor coil module, the switch module, the charging start buffer module, and the DC charging port form four different charging and discharging circuits in sequence. The three motor coils are connected in series in the charging and discharging circuits to make the current flowing through the three motor coils equal.

[0010] Optionally, the power module includes six power switches. The first terminal of the first power switch is connected to the first terminals of the second and third power switches. The second terminal of the first power switch is connected to the first terminal of the fourth power switch and is also connected to the first terminal of the first motor coil. The second terminal of the second power switch is connected to the first terminal of the fifth power switch and is also connected to the first terminal of the second motor coil. The second terminal of the third power switch is connected to the first terminal of the sixth power switch and is also connected to the first terminal of the third motor coil. The second terminal of the fourth power switch is connected to the second terminals of the fifth and sixth power switches. The first terminal of the first power switch is also connected to the positive terminal of the power battery, and the second terminal of the fourth power switch is also connected to the negative terminal of the power battery. Control signals are input to the control terminals of the six power switches.

[0011] Optionally, the charging start-up buffer module includes a first resistor, a first capacitor, and a first switch. The boost charging circuit further includes a second switch. One end of the first switch is connected to the positive terminal of the DC charging port and the first terminal of the first power switch. The other end of the first switch is connected to the first terminal of the first capacitor. The second terminal of the first capacitor is connected to the negative terminal of the DC charging port via the second switch connected in series. The first resistor is connected in parallel with the first capacitor.

[0012] Optionally, the switching module includes a switching mode unit and a switching balancing unit. The switching mode unit is connected to the charging start buffer module and the motor coil module. The switching mode unit is used to switch the operating mode of the motor coil module. The switching balancing unit is connected to the motor coil module and the power module. When the switching mode unit switches the operating mode of the motor coil module to the charging and discharging mode, the switching balancing unit connects the first motor coil, the second motor coil, and the third motor coil in series in sequence, so that the current flowing through the three motor coils is equal.

[0013] Optionally, the switching mode unit includes a first mode switch and a second mode switch, and the switching balancing unit includes a first balancing switch and a second balancing switch. The second end of the first motor coil is connected to the second end of the second motor coil after passing through the first mode switch in series. The second end of the second motor coil is connected to the second end of the third motor coil after passing through the second mode switch in series. The second end of the third motor coil is also connected to the second end of the first capacitor. The first end of the second motor coil is connected to the second end of the first motor coil after passing through the first balancing switch in series. The first end of the third motor coil is connected to the second end of the second motor coil after passing through the second balancing switch in series.

[0014] Optionally, the switching mode unit includes a third mode switch, the switching balance unit includes a third balance switch, the second end of the second motor coil is connected to the second end of the third motor coil after the third mode switch connected in series, the second end of the third motor coil is also connected to the second end of the first capacitor, and the first end of the second motor coil is connected to the first end of the third motor coil after the third balance switch connected in series.

[0015] Optionally, the switching mode unit includes a fourth mode switch, and the switching balance unit includes a fourth balance switch, a first single-pole double-throw switch, and a second single-pole double-throw switch. The second end of the second motor coil is connected to the second end of the third motor coil via the fourth mode switch connected in series. The second end of the third motor coil is also connected to the second end of the first capacitor. The first end of the second motor coil is connected to the first end of the third motor coil via the fourth balance switch connected in series. The fixed end of the first single-pole double-throw switch is connected to the second end of the second power switch. The first contact end of the first single-pole double-throw switch is connected to the first end of the first motor coil. The second contact end of the first single-pole double-throw switch is connected to the first end of the second motor coil. The fixed end of the second single-pole double-throw switch is connected to the second end of the third power switch. The first contact end of the second single-pole double-throw switch is connected to the fixed end of the first single-pole double-throw switch. The second contact end of the second single-pole double-throw switch is connected to the first end of the third motor coil.

[0016] Optionally, in the charging and discharging mode, the second terminal of the first capacitor is connected in series with the third motor coil, the second motor coil, and the first motor coil, and then connected to the second terminal of the first power switch.

[0017] Optionally, in the charging and discharging mode, after the second terminal of the first capacitor is connected in series with the third motor coil, the second motor coil and the first motor coil, it is simultaneously connected to the second terminal of the first power switch, the second terminal of the second power switch and the second terminal of the third power switch.

[0018] This invention provides a method for boost charging of electric vehicles, comprising:

[0019] Before the power battery is boosted and charged through the electric vehicle boost charging circuit, the motor coil module is switched to the charging and discharging mode through the switching module. The power battery is discharged to charge the charging start buffer module and the motor coil module for the first time. After the first charge, the motor coil module maintains the voltage of the charging start buffer module to buffer and boost the voltage of the charging start buffer module to the rated voltage of the DC charging port.

[0020] After the voltage of the charging start-up buffer module is boosted to the rated voltage of the DC charging port, a DC power supply is connected through the DC charging port. The motor coil module is then charged a second time through the DC power supply. The motor coil module after the second charge and the DC power supply are then used to boost the voltage of the power battery.

[0021] This invention provides a boost charging circuit and method for electric vehicles, including a power module, a motor coil module, a charging start-up buffer module, and a switch module. The power module is connected to the motor coil module, the charging start-up buffer module, a DC charging port, and a power battery. The motor coil module includes three motor coils. The switch module is connected to the motor coil module and controls its operating mode. When the operating mode is charging / discharging mode, the power battery, power module, motor coil module, charging start-up buffer module, switch module, and DC charging port sequentially form four different charging / discharging circuits. In each charging / discharging circuit, the three motor coils are connected in series in the four different circuits, and the current flowing through the three motor coils is equal. This invention switches the traditional "star-connected motor" connection to a series connection through the switch module. In the charging / discharging circuit, this ensures that the current flowing into the three motor coils is equal, reducing output torque, improving customer driving comfort, increasing the energy storage capacity of the equivalent inductance, eliminating current ripple during charging, and increasing the lifespan of other electronic components.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0024] Figure 1 This is a block diagram of the electric vehicle boost charging circuit in an embodiment of the present invention;

[0025] Figure 2 This is a circuit diagram of a common positive electrode electric vehicle boost charging circuit shown in the first exemplary embodiment of the present invention;

[0026] Figure 3 This is a circuit diagram of a common positive electrode electric vehicle boost charging circuit shown in a second exemplary embodiment of the present invention;

[0027] Figure 4 This is a circuit diagram of a common positive electrode electric vehicle boost charging circuit shown in the third exemplary embodiment of the present invention;

[0028] Figure 5 This is a circuit diagram of a common negative electrode electric vehicle boost charging circuit shown in the first exemplary embodiment of the present invention;

[0029] Figure 6 This is a circuit diagram of a common negative electrode electric vehicle boost charging circuit shown in a second exemplary embodiment of the present invention;

[0030] Figure 7 This is a circuit diagram of a common negative electrode electric vehicle boost charging circuit shown in the third exemplary embodiment of the present invention. Detailed Implementation

[0031] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0032] The inventors discovered that power and driving range are key indicators for electric vehicles and factors consumers consider when purchasing a car. To achieve better power and longer driving range, high-voltage batteries have received widespread attention. Currently, existing boost technology can directly charge high-voltage batteries through low-voltage DC charging ports, solving the problem that low-voltage DC charging stations cannot charge high-voltage batteries. However, in related technologies, the three-phase coils of the motor and power modules are typically reused to charge the battery. During charging, the current output of the motor coils becomes unbalanced, generating torque that causes vehicle vibration and affects the customer experience. Furthermore, if the equivalent inductance of the motor is low, large current ripples will occur during charging, increasing the risk of damage to other electronic components.

[0033] To solve the above technical problems, a boost charging circuit for electric vehicles is provided, including a power module, a motor coil module, a charging start buffer module, and a switch module. The switch control module controls the working mode of the motor coil module. In the charging and discharging mode, the power module, the motor coil module, the charging start buffer module, the switch module, the power battery, and the DC charging pile form four different charging and discharging circuits. In the charging and discharging circuit, the three motor coils in the motor coil module are connected in series in sequence through the switch module so that the current flowing through the three motor coils is equal.

[0034] like Figure 1 As shown, this embodiment of the invention provides a boost charging circuit for electric vehicles, used to balance the current flowing into the motor coil in the boost charging circuit. It includes a power module, a motor coil module, a charging start-up buffer module, and a switching module. The power module is connected to the motor coil module and the charging start-up buffer module respectively, and is also connected to the power battery. The charging start-up buffer module is also connected to the DC charging port. The motor coil module includes three motor coils. The switching module is connected to the motor coil module and is used to switch the operating mode of the motor coil module. The operating mode of the motor coil module includes a charging and discharging mode. When the switching module switches the motor coil module to the charging and discharging mode, the power battery, power module, motor coil module, switching module, charging start-up buffer module, and DC charging port successively form four different charging and discharging circuits. The three motor coils are connected in series in the charging and discharging circuits to ensure that the current flowing through the three motor coils is equal.

[0035] Example 1

[0036] In detail, in the embodiments of the present invention, such as Figure 2As shown, the power module includes six power switches, each containing a body diode. The first terminal of the first power switch Q1 is connected to the first terminals of the second power switch Q2 and the third power switch Q3. The second terminal of the first power switch Q1 is connected to the first terminal of the fourth power switch Q4. The second terminal of the first power switch Q1 is also connected to the first terminal of the first motor coil L1. The second terminal of the second power switch Q2 is connected to the first terminal of the fifth power switch Q5. The second terminal of the second power switch Q2 is also connected to the first terminal of the second motor coil L2. The second terminal of the third power switch Q3 is connected to the first terminal of the sixth power switch Q6. The second terminal of the third power switch Q3 is also connected to the first terminal of the third motor coil L3. The second terminal of the fourth power switch Q4 is connected to the second terminals of the fifth power switch Q5 and the sixth power switch Q6. The first terminal of the first power switch Q1 is also connected to the positive terminal of the power battery Vout, and the second terminal of the fourth power switch Q4 is also connected to the negative terminal of the power battery Vout. The control terminals of the six power switches input control signals, which can be pulse width modulation waves with a specific duty cycle.

[0037] In detail, such as Figure 2 As shown, the charging start-up buffer module includes a first resistor R1, a first capacitor C1, and a first switch K1. The boost charging circuit also includes a second switch K2. One end of the first switch K1 is connected to the positive terminal of the DC charging port Vin and the first terminal of the first power switch Q1. The other end of the first switch K1 is connected to the first terminal of the first capacitor C1. The second terminal of the first capacitor C1 is connected to the negative terminal of the DC charging port Vin after passing through the second switch K2 connected in series. The first resistor R1 is connected in parallel with the first capacitor C1.

[0038] In detail, the motor coil module has two operating modes: normal drive mode and charging / discharging mode. The switching module controls the switching of the motor coil module's operating modes.

[0039] In detail, the switching module includes a switching mode unit and a switching balance unit. The switching mode unit is connected to the charging start buffer module and the motor coil module. The switching mode unit is used to switch the operating mode of the motor coil module. The switching balance unit is connected to the motor coil module and the power module. When the switching mode unit switches the operating mode of the motor coil module to the charging and discharging mode, the switching balance unit connects the first motor coil, the second motor coil and the third motor coil in series in sequence so that the current flowing through the three motor coils is equal.

[0040] In detail, such as Figure 2 As shown, the boost charging circuit also includes a second capacitor C2, which is connected in series between the positive terminal of the power battery Vout and the negative terminal of the power battery Vout.

[0041] More in detail, such as Figure 2As shown, the switching mode unit includes a first mode switch K31 and a second mode switch K32, and the switching balance unit includes a first balance switch K41 and a second balance switch K42. The second end of the first motor coil L1 is connected to the second end of the second motor coil L2 via the first mode switch K31 connected in series. The second end of the second motor coil L2 is connected to the second end of the third motor coil L3 via the second mode switch K32 connected in series. The second end of the third motor coil L3 is also connected to the second end of the first capacitor C1. The first end of the second motor coil L2 is connected to the second end of the first motor coil L1 via the first balance switch K41 connected in series. The first end of the third motor coil L3 is connected to the second end of the second motor coil L2 via the second balance switch K42 connected in series.

[0042] More specifically, in embodiments of the present invention, Figure 2 The specific working principle of the electric vehicle boost charging circuit is as follows:

[0043] like Figure 2 As shown, the power battery and the DC charging port share a common positive terminal. The boost charging circuit is initially in standby mode. If no boost charging command is received, it remains in standby mode, the motor coil module is in normal drive mode, the first mode switch K31 and the second mode switch K32 are closed, and the first balance switch K41 and the second balance switch K42 are open. When the boost charging circuit receives a boost charging command, the motor coil module enters charging / discharging mode, opening the first mode switch K31 and the second mode switch K32, and closing the first balance switch K41 and the second balance switch K42. According to relevant charging specifications, DC charging piles cannot directly charge after plugging in the charging gun; the voltage value at the interface must meet the requirements for normal output.

[0044] (1) Close the first switch K1 and the second switch K2, and turn off the first power switch Q1, the second power switch Q2, the third power switch Q3, the fifth power switch Q5 and the sixth power switch Q6. Input a specific duty cycle pulse width modulation wave to the control terminal of the fourth power switch Q4. When the fourth power switch Q4 is turned on, the first charging circuit is formed. The current flows from the positive terminal of the power battery Vout through the first switch K1, the first capacitor C1 or the first resistor R1, the third motor coil L3, the second balance switch K42, the second motor coil L2, the first balance switch K41, the first motor coil L1 and the fourth power switch Q4, and then into the negative terminal of the power battery Vout. The discharge process performs the first charge on the first capacitor C1 and the three motor coils. When the fourth power switch Q4 is turned off, a discharge circuit is formed, and the currents in the first motor coil L1, the second motor coil L2, and the third motor coil L3 change. The surrounding magnetic field changes, thereby generating self-inductance. The current generated by the self-inductance of the first motor coil L1, the second motor coil L2, and the third motor coil L3 flows from the first end of the first motor coil L1 through the body diode D1 in the first power switch Q1, the first switch K1, the first capacitor C1 or the first resistor R1, and then flows back to the second end of the third motor coil L3. The voltage across the first capacitor C1 is maintained by the self-inductance generated by the three motor coils after the first charge.

[0045] (2) When the voltage across the first capacitor C1 reaches the rated voltage and the duration exceeds the preset time threshold, the voltage across the DC charging port is boosted to the rated voltage, and the boost charging circuit establishes a charging connection with the DC charging port. Because the DC charging port voltage is lower than the power battery voltage, during charging, the voltage of the motor coil module needs to be superimposed with the voltage of the DC charging port to meet the voltage requirements of the DC charging port for charging the power battery. Therefore, the motor coil needs to be charged before charging the power battery.

[0046] (3) Disconnect the first switch K1 and close the second switch K2, turning off the second power switch Q2, the third power switch Q3, the fourth power switch Q4, the fifth power switch Q5, and the sixth power switch Q6. Input a pulse width modulation wave with a specific duty cycle to the control terminal of the first power switch Q1. When the first power switch Q1 is turned on, a second charging circuit is formed. Current flows from the positive terminal of the DC charging port Vin through the first power switch Q1, the first motor coil L1, the first balance switch K41, the second motor coil L2, the second balance switch K42, the third motor coil L3, and the second switch K2, and then into the negative terminal of the DC charging port Vin. The charging port is connected to a DC power supply, which performs a second charge on the first motor coil L1, the second motor coil L2, and the third motor coil L3. When the first power switch Q1 is turned off, a third charging circuit is formed. The current flows from the positive terminal of the DC charging port Vin through the power battery Vout, the body diode D4 in the fourth power switch Q4, the first motor coil L1, the first balance switch K41, the second motor coil L2, the second balance switch K42, the third motor coil L3, and the second switch K2, and then flows into the negative terminal of the DC charging port Vin. Combined with the three motor coils after the second charge and the DC power supply, the power battery Vout is boosted and charged.

[0047] Example 2

[0048] In detail, in the embodiments of the present invention, the specific connection methods of the power battery, power module, motor coil module, charging start buffer module, and DC charging port are the same as in Embodiment 1, and will not be repeated here.

[0049] In detail, such as Figure 3 As shown, the switching mode unit includes a third mode switch K33, the switching balance unit includes a third balance switch K43, the second end of the second motor coil L2 is connected to the second end of the third motor coil L3 after passing through the third mode switch K33 in series, the second end of the third motor coil L3 is also connected to the second end of the first capacitor C1, and the first end of the second motor coil L2 is connected to the first end of the third motor coil L3 after passing through the third balance switch K43 in series.

[0050] More specifically, in embodiments of the present invention, Figure 3 The specific working principle of the electric vehicle boost charging circuit is as follows:

[0051] The connection method of the switching module in the electric vehicle boost charging circuit is as follows: Figure 3As shown, the power battery and the DC charging port share the same positive terminal. The boost charging circuit is initially in standby mode. If no boost charging command is received, it remains in standby mode, the motor coil module is in normal drive mode, the third mode switch K33 is closed, and the third balance switch K43 is open. When the boost charging circuit receives a boost charging command, the motor coil module enters charge / discharge mode, the third mode switch K33 is opened, and the third balance switch K43 is closed. According to charging specifications, DC charging piles cannot directly charge after plugging in the charging gun; the voltage value at the interface must meet the requirements before normal output can occur.

[0052] (1) Close the first switch K1 and the second switch K2, and turn off the first power switch Q1, the second power switch Q2, the third power switch Q3, the fifth power switch Q5 and the sixth power switch Q6. Input a pulse width modulation wave with a specific duty cycle to the control terminal of the fourth power switch Q4. When the fourth power switch Q4 is turned on, the first charging circuit is formed. The current flows from the positive terminal of the power battery Vout through the first switch K1, the first capacitor C1 or the first resistor R1, the third motor coil L3, the third balance switch K43, the second motor coil L2, the first motor coil L1 and the fourth power switch Q4, and then into the negative terminal of the power battery Vout. The power battery Vout discharges to the first Capacitor C1 and the three motor coils undergo the first charging. When the fourth power switch Q4 is turned off, a discharge circuit is formed. The current in the first motor coil L1, the second motor coil L2, and the third motor coil L3 changes, and the surrounding magnetic field changes, thereby generating self-inductance. The current generated by the self-inductance of the first motor coil L1, the second motor coil L2, and the third motor coil L3 flows from the first end of the first motor coil L1 through the diode D1 in the first power switch Q1, the first switch K1, the first capacitor C1 or the first resistor R1, and then flows back to the second end of the third motor coil L3. The voltage value across the first capacitor C1 is maintained by the current generated by the self-inductance of the three motor coils after the first charging.

[0053] (2) When the voltage across the first capacitor C1 reaches the rated voltage and the duration exceeds the preset time threshold, the voltage across the DC charging port is boosted to the rated voltage, and the boost charging circuit establishes a charging connection with the DC charging port. Because the DC charging port voltage is lower than the power battery voltage, during charging, the voltage of the motor coil module needs to be superimposed with the voltage of the DC charging port to meet the voltage requirements of the DC charging port for charging the power battery. Therefore, the motor coil needs to be charged before charging the power battery.

[0054] (3) Disconnect the first switch K1 and close the second switch K2, turn off the second power switch Q2, the third power switch Q3, the fourth power switch Q4, the fifth power switch Q5 and the sixth power switch Q6, and input a pulse width modulation wave with a specific duty cycle to the control terminal of the first power switch Q1; when the first power switch Q1 is turned on, the second charging circuit is formed, and the current flows from the positive terminal of the DC charging port Vin through the first power switch Q1, the first motor coil L1, the second motor coil L2, the third balance switch K43, the third motor coil L3 and the second switch K2 in sequence before flowing into the negative terminal of the DC charging port Vin, and the DC charging port is connected to the DC power supply. The power supply, a DC power source, performs a second charge on the first motor coil L1, the second motor coil L2, and the third motor coil L3. When the first power switch Q1 is turned off, a third charging circuit is formed. The DC charging port Vin is connected to the DC power supply. Current flows from the positive terminal of the DC charging port Vin through the power battery Vout, the diode D4 in the fourth power switch Q4, the first motor coil L1, the second motor coil L2, the third balance switch K43, the third motor coil L3, and the second switch K2, before flowing into the negative terminal of the DC charging port Vin. Combined with the three motor coils after the second charge and the DC power supply, the power battery Vout is boosted and charged.

[0055] Example 3

[0056] In detail, in the embodiments of the present invention, the specific connection methods of the power battery, power module, motor coil module, charging start buffer module, and DC charging port are the same as in Embodiment 1, and will not be repeated here.

[0057] In detail, such as Figure 4 As shown, the switching mode unit includes a fourth mode switch K34, and the switching balance unit includes a fourth balance switch K44, a first single-pole double-throw switch K5, and a second single-pole double-throw switch K6. The second end of the second motor coil L2 is connected to the second end of the third motor coil L3 via the fourth mode switch K34 connected in series. The second end of the third motor coil L3 is also connected to the second end of the first capacitor C1. The first end of the second motor coil L2 is connected to the first end of the third motor coil L3 via the fourth balance switch K44 connected in series. The fixed end of the first single-pole double-throw switch K5 is connected to the second end of the second power switch Q2. The first contact end of the first single-pole double-throw switch K5 is connected to the first end of the first motor coil L1. The second contact end of the first single-pole double-throw switch K5 is connected to the first end of the second motor coil L2. The fixed end of the second single-pole double-throw switch K6 is connected to the second end of the third power switch Q3. The first contact end of the second single-pole double-throw switch K6 is connected to the fixed end of the first single-pole double-throw switch K5. The second contact end of the second single-pole double-throw switch K6 is connected to the first end of the third motor coil L3.

[0058] More specifically, in embodiments of the present invention, Figure 4 The specific working principle of the electric vehicle boost charging circuit is as follows:

[0059] The connection method of the switching module in the electric vehicle boost charging circuit is as follows: Figure 4 As shown, the power battery and the DC charging port share the same positive terminal. The boost charging circuit is initially in standby mode. If no boost charging command is received, it remains in standby mode, the motor coil module is in normal drive mode, the fourth mode switch K34 is off, the fourth balance switch K44 is off, the first single-pole double-throw switch K5 is set to the second contact terminal K52, and the second single-pole double-throw switch K6 is set to the second contact terminal K62. When the boost charging circuit receives a boost charging command, the motor coil module is in charge / discharge mode, the fourth mode switch K34 is disconnected and the fourth balance switch K44 is closed, the first single-pole double-throw switch K5 is set to the first contact terminal K51, and the second single-pole double-throw switch K6 is set to the first contact terminal K61. According to relevant charging specifications, DC charging piles cannot directly charge after plugging in the charging gun; the voltage value at the interface must be detected to meet the requirements before normal output can be achieved.

[0060] (1) Close the first switch K1 and the second switch K2, and turn off the first power switch Q1, the second power switch Q2 and the third power switch Q3. Input a pulse width modulation wave with a specific duty cycle to the control terminals of the fourth power switch Q4, the fifth power switch Q5 and the sixth power switch Q6. When the fourth power switch Q4, the fifth power switch Q5 and the sixth power switch Q6 are turned on, the first charging voltage is formed. The current flows from the positive terminal of the power battery through the first switch K1, the first capacitor C1 or the first resistor R1, the third motor coil L3, the fourth balance switch K44, the second motor coil L2 and the first motor coil L1, and then simultaneously flows into the fourth power switch Q4, the fifth power switch Q5 and the sixth power switch Q6, and finally into the negative terminal of the power battery Vout. The power battery Vout discharges through the first capacitor C1. The three motor coils undergo an initial charge. When the fourth power switch Q4, the fifth power switch Q5, and the sixth power switch Q6 are turned off, a discharge circuit is formed. The current in the first motor coil L1, the second motor coil L2, and the third motor coil L3 changes, and the surrounding magnetic field changes, thereby generating self-induction. The current generated by the self-induction of the first motor coil L1, the second motor coil L2, and the third motor coil L3 flows from the first end of the first motor coil L1 through the diode D1 in the first power switch Q1, the diode D2 in the second power switch Q2, and the diode D3 in the third power switch Q3, and then flows sequentially through the first switch K1, the first capacitor C1 or the first resistor R1 before flowing back to the second end of the third motor coil L3. The voltage across the first capacitor C1 is maintained by the current generated by the self-induction of the three motor coils after the first charge.

[0061] (2) When the voltage of the first capacitor C1 reaches the buffer voltage threshold and the duration is longer than the preset time threshold, the voltage across the DC charging port is raised to the buffer voltage threshold, and the boost charging circuit establishes a charging connection with the DC charging port. Because the voltage of the DC charging port is lower than the voltage of the power battery, during charging, the voltage of the motor coil module needs to be superimposed with the voltage of the DC charging port to meet the voltage requirements of the DC charging port for charging the power battery. Therefore, the motor coil needs to be charged before charging the power battery.

[0062] (3) Disconnect the first switch K1 and close the second switch K2, turning off the fourth power switch Q4, the fifth power switch Q5, and the sixth power switch Q6. Input a pulse width modulation wave with a specific duty cycle to the control terminals of the first power switch Q1, the second power switch Q2, and the third power switch Q3. When the first power switch Q1, the second power switch Q2, and the third power switch Q3 are turned on, a second charging circuit is formed. The DC charging port is connected to a DC power supply. Current flows from the positive terminal of the DC charging port Vin through the first power switch Q1, the second power switch Q2, and the third power switch Q3, then into the first terminal of the first motor coil L1, and sequentially through the first motor coil L1, the second motor coil L2, the fourth balance switch K44, the third motor coil L3, and the second switch K2 before flowing into the negative terminal of the DC charging port Vin. The DC power supply... The first motor coil L1, the second motor coil L2, and the third motor coil L3 undergo a second charging. When the first power switch Q1, the second power switch Q2, and the third power switch Q3 are turned off, a third charging circuit is formed. The DC charging port is connected to a DC power supply. The current flows from the positive terminal of the DC charging port Vin through the power battery Vout in sequence, and then flows into the body diode D4 in the fourth power switch Q4, the body diode D5 in the fifth power switch Q5, and the body diode D6 in the sixth power switch Q6, before converging at the first terminal of the first motor coil L1. After that, the current flows through the first motor coil L1, the second motor coil L2, the third balance switch K44, the third motor coil L3, and the second switch K2 in sequence before flowing into the negative terminal of the DC charging port Vin. Combined with the three motor coils after the second charging and the DC power supply, the power battery Vout is boosted and charged.

[0063] In detail, such as Figure 2 or Figure 3 As shown, in charge / discharge mode, the second terminal of the first capacitor C1 is connected in series with the third motor coil L3, the second motor coil and L2. The first motor coil L1 is then connected to the second terminal of the first power switch Q1.

[0064] In detail, such as Figure 4 As shown, in charge / discharge mode, the second terminal of the first capacitor C1 is connected in series with the third motor coil L3, the second motor coil L2 and the first motor coil L1, and then connected to the second terminal of the first power switch Q1, the second terminal of the second power switch Q2 and the second terminal of the third power switch Q3.

[0065] It needs to be emphasized that, Figures 5-7 The electric vehicle boost charging circuit, including the specific structure of the power battery, power module, motor coil module, charging start buffer module, and DC charging port, is as follows: Figure 2The same as in Example 1, so it will not be repeated here. Figures 5-7 The difference in the electric vehicle boost charging circuit lies in the connection method between the power battery and the DC charging port circuit. Specifically, the power battery and the DC charging port are connected in a common negative terminal configuration. The connection method of the first switch K1 and the second switch K2 is also different. Specifically, the first terminal of the first capacitor C1 is connected in series with the first switch K1 and the second switch K2, and then connected to the positive terminal of the DC charging port Vin. The connection method of the switch module has been adjusted accordingly to make the power battery and the DC charging port have a common negative terminal configuration. Figure 5 The working principle and Figure 2 The same in Figure 6 The working principle and Figure 3 The same in Figure 7 The working principle and Figure 4 The similarities are the same in other languages, so I will not repeat them here.

[0066] The present invention also provides a method for boost charging of electric vehicles, comprising:

[0067] S1. Provide the above-mentioned electric vehicle boost charging circuit;

[0068] S2. Before boosting the power battery through the electric vehicle boost charging circuit, the motor coil module is switched to the charging and discharging mode through the switching module. The power battery is discharged to charge the charging start buffer module and the motor coil module for the first time. After the first charge, the motor coil module maintains the voltage of the charging start buffer module to buffer and boost the voltage of the charging start buffer module to the rated voltage of the DC charging port.

[0069] S3. After the voltage of the charging start-up buffer module is boosted to the rated voltage of the DC charging port, the DC power supply is connected through the DC charging port. The motor coil module is charged for the second time through the DC power supply. Then, the motor coil module after the second charge and the DC power supply are combined to boost the power battery.

[0070] This invention provides a boost charging circuit and method for electric vehicles, including a power module, a motor coil module, a charging start-up buffer module, and a switch module. The power module is connected to the motor coil module, the charging start-up buffer module, a DC charging port, and a power battery. The motor coil module includes three motor coils. The switch module is connected to the motor coil module and controls its operating mode. When the operating mode is charging / discharging mode, the power battery, power module, motor coil module, charging start-up buffer module, switch module, and DC charging port sequentially form four different charging / discharging circuits. In each charging / discharging circuit, the three motor coils are connected in series in the four different circuits, and the current flowing through the three motor coils is equal. This invention switches the traditional "star-connected motor" connection to a series connection through the switch module. In the charging / discharging circuit, this ensures that the current flowing into the three motor coils is equal, reducing output torque, improving customer driving comfort, increasing the energy storage capacity of the equivalent inductance, eliminating current ripple during charging, and increasing the lifespan of other electronic components.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A boost charging circuit for electric vehicles, used to balance the current flowing into the motor coil in the boost charging circuit, characterized in that, It includes a power module, a motor coil module, a charging start-up buffer module, and a switch module. The power module is connected to the motor coil module and the charging start-up buffer module respectively. The power module is also connected to the power battery, and the charging start-up buffer module is also connected to the DC charging port. The motor coil module includes three motor coils. The switch module is connected to the motor coil module and is used to switch the operating mode of the motor coil module. The operating mode of the motor coil module includes a charging and discharging mode. When the switch module switches the motor coil module to the charging and discharging mode, the power battery, the power module, the motor coil module, the switch module, the charging start buffer module, and the DC charging port successively form four different charging and discharging circuits. The three motor coils are connected in series in the charging and discharging circuits so that the current flowing through the three motor coils is equal.

2. The electric vehicle boost charging circuit according to claim 1, characterized in that, The power module includes six power switches. The first terminal of the first power switch is connected to the first terminals of the second and third power switches. The second terminal of the first power switch is connected to the first terminal of the fourth power switch. The second terminal of the first power switch is also connected to the first terminal of the first motor coil. The second terminal of the second power switch is connected to the first terminal of the fifth power switch. The second terminal of the second power switch is also connected to the first terminal of the second motor coil. The second terminal of the third power switch is connected to the first terminal of the sixth power switch. The second terminal of the third power switch is also connected to the first terminal of the third motor coil. The second terminal of the fourth power switch is connected to the second terminals of the fifth and sixth power switches. The first terminal of the first power switch is also connected to the positive terminal of the power battery, and the second terminal of the fourth power switch is also connected to the negative terminal of the power battery. The control terminals of the six power switches input control signals.

3. The electric vehicle boost charging circuit according to claim 2, characterized in that, The charging start-up buffer module includes a first resistor, a first capacitor, and a first switch. The boost charging circuit also includes a second switch. One end of the first switch is connected to the positive terminal of the DC charging port and the first terminal of the first power switch. The other end of the first switch is connected to the first terminal of the first capacitor. The second terminal of the first capacitor is connected to the negative terminal of the DC charging port via the second switch connected in series. The first resistor is connected in parallel with the first capacitor.

4. The electric vehicle boost charging circuit according to claim 3, characterized in that, The switching module includes a switching mode unit and a switching balance unit. The switching mode unit is connected to the charging start buffer module and the motor coil module. The switching mode unit is used to switch the operating mode of the motor coil module. The switching balance unit is connected to the motor coil module and the power module. When the switching mode unit switches the operating mode of the motor coil module to the charging and discharging mode, the switching balance unit connects the first motor coil, the second motor coil, and the third motor coil in series in sequence so that the current flowing through the three motor coils is equal.

5. The electric vehicle boost charging circuit according to claim 4, characterized in that, The switching mode unit includes a first mode switch and a second mode switch. The switching balance unit includes a first balance switch and a second balance switch. The second end of the first motor coil is connected to the second end of the second motor coil after passing through the first mode switch in series. The second end of the second motor coil is connected to the second end of the third motor coil after passing through the second mode switch in series. The second end of the third motor coil is also connected to the second end of the first capacitor. The first end of the second motor coil is connected to the second end of the first motor coil after passing through the first balance switch in series. The first end of the third motor coil is connected to the second end of the second motor coil after passing through the second balance switch in series.

6. The electric vehicle boost charging circuit according to claim 4, characterized in that, The switching mode unit includes a third mode switch, the switching balance unit includes a third balance switch, the second end of the second motor coil is connected to the second end of the third motor coil after the third mode switch connected in series, the second end of the third motor coil is also connected to the second end of the first capacitor, and the first end of the second motor coil is connected to the first end of the third motor coil after the third balance switch connected in series.

7. The electric vehicle boost charging circuit according to claim 4, characterized in that, The switching mode unit includes a fourth mode switch, and the switching balance unit includes a fourth balance switch, a first single-pole double-throw switch, and a second single-pole double-throw switch. The second end of the second motor coil is connected to the second end of the third motor coil via the fourth mode switch connected in series. The second end of the third motor coil is also connected to the second end of the first capacitor. The first end of the second motor coil is connected to the first end of the third motor coil via the fourth balance switch connected in series. The fixed end of the first single-pole double-throw switch is connected to the second end of the second power switch. The first contact end of the first single-pole double-throw switch is connected to the first end of the first motor coil. The second contact end of the first single-pole double-throw switch is connected to the first end of the second motor coil. The fixed end of the second single-pole double-throw switch is connected to the second end of the third power switch. The first contact end of the second single-pole double-throw switch is connected to the fixed end of the first single-pole double-throw switch. The second contact end of the second single-pole double-throw switch is connected to the first end of the third motor coil.

8. The electric vehicle boost charging circuit according to claim 5 or 6, characterized in that, In the charging and discharging mode, the second terminal of the first capacitor is connected in series with the third motor coil, the second motor coil, and the first motor coil, and then connected to the second terminal of the first power switch.

9. The electric vehicle boost charging circuit according to claim 7, characterized in that, In the charging and discharging mode, the second terminal of the first capacitor is connected in series with the third motor coil, the second motor coil and the first motor coil, and then connected to the second terminal of the first power switch, the second terminal of the second power switch and the second terminal of the third power switch.

10. A method for boost charging of electric vehicles, characterized in that, include: Provides an electric vehicle boost charging circuit as described in any one of claims 1-9; Before the power battery is boosted and charged through the electric vehicle boost charging circuit, the motor coil module is switched to the charging and discharging mode through the switching module. The power battery is discharged to charge the charging start buffer module and the motor coil module for the first time. After the first charge, the motor coil module maintains the voltage of the charging start buffer module to buffer and boost the voltage of the charging start buffer module to the rated voltage of the DC charging port. After the voltage of the charging start-up buffer module is boosted to the rated voltage of the DC charging port, a DC power supply is connected through the DC charging port. The motor coil module is then charged a second time through the DC power supply. The motor coil module after the second charge and the DC power supply are then used to boost the voltage of the power battery.

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