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CN-116780895-B - Boost charging circuit and method for electric automobile

CN116780895BCN 116780895 BCN116780895 BCN 116780895BCN-116780895-B

Abstract

The invention provides a boost charging circuit and a boost charging method for an electric automobile, wherein a motor coil module comprises three motor coils, a switch module is connected with the motor coil module, the working mode of the motor coil module is controlled through the switch module, when the working mode is a charge-discharge mode, a power battery, a power module, the motor coil module, a charge starting buffer module, the switch module and a direct current charging port sequentially form four different charge-discharge loops, and in the charge-discharge loops, the three motor coils are sequentially connected in series in the four charge-discharge loops, so that currents flowing through the three motor coils are equal. According to the invention, the traditional star motor connection mode is switched into series connection through the switch module, and the current flowing into the motor coil is consistent in size and direction in the charge-discharge loop, so that the output torque is reduced, the comfort level of a customer vehicle is improved, the electric quantity storage of an equivalent inductor is increased, the current ripple generated in the charging process is eliminated, and the service lives of other electronic devices are prolonged.

Inventors

  • PENG YANG
  • CHEN JIAN
  • LIN YUTING

Assignees

  • 深蓝汽车科技有限公司

Dates

Publication Date
20260508
Application Date
20230620

Claims (10)

  1. 1. The boost charging circuit of the electric automobile is used for balancing the current flowing into a motor coil in the boost charging circuit and is characterized by comprising a power module, a motor coil module, a charging starting buffer module and a switch module, wherein the power module is respectively connected with the motor coil module and the charging starting buffer module, the power module is also connected with a power battery, and the charging starting buffer module is also connected with a direct-current charging port; The motor coil module comprises three motor coils, the switch module is connected with the motor coil module, the switch module is used for switching the working mode of the motor coil module, the working mode of the motor coil module comprises 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 starting buffer module and the direct current charging port sequentially form four different charging and discharging loops, and the three motor coils are sequentially connected in series in the charging and discharging loops so that currents flowing through the three motor coils are equal.
  2. 2. The boost charging circuit of claim 1, wherein the power module comprises six power switches, a first end of a first one of the power switches is connected to a first end of a second one of the power switches and a first end of a third one of the power switches, a second end of the first one of the power switches is connected to a first end of a fourth one of the power switches, a second end of the first one of the power switches is connected to a first end of a first one of the motor coils, a second end of the second one of the power switches is connected to a first end of a fifth one of the power switches, a second end of the second one of the power switches is connected to a first end of a second one of the motor coils, a second end of the third one of the power switches is connected to a first end of a third one of the motor coils, a second end of the fourth one of the power switches is connected to a second end of the fifth one of the power switches and a first end of the sixth one of the power switches, a second end of the second one of the power switches is connected to a second one of the power switches, and a second end of the fourth one of the power switches is connected to a second one of the power switch is connected to a negative electrode of the power battery.
  3. 3. The boost charging circuit of claim 2, wherein the charge start buffer module comprises a first resistor, a first capacitor, a first switch, and a second switch, one end of the first switch is connected with the positive pole of the dc charging port and the first end of the first power switch, the other end of the first switch is connected with the first end of the first capacitor, the second end of the first capacitor is connected with the negative pole of the dc charging port after being connected with the second switch in series, and the first resistor is connected with the first capacitor in parallel.
  4. 4. The electric vehicle boost charging circuit according to claim 3, wherein the switch module comprises a switch mode unit and a switch balancing unit, the switch mode unit is connected with the charge starting buffer module and the motor coil module, the switch mode unit is used for switching the working mode of the motor coil module, the switch balancing unit is connected with the motor coil module and the power module, and when the switch mode unit switches the working mode of the motor coil module to the charge-discharge mode, the switch balancing unit connects a first motor coil, a second motor coil and a third motor coil in series in sequence, so that currents flowing through the three motor coils are equal.
  5. 5. The boost charging circuit of claim 4, wherein the switch-mode unit comprises a first mode switch and a second mode switch, the switch-balance unit comprises a first balance switch and a second balance switch, the second end of a first motor coil is connected with the second end of a second motor coil after passing through the first mode switch in series, the second end of a second motor coil is connected with the second end of a third motor coil after passing through the second mode switch in series, the second end of the third motor coil is also connected with the second end of the first capacitor, the first end of the second motor coil is connected with the second end of a first motor coil after passing through the first balance switch in series, and the first end of the third motor coil is connected with the second end of the second motor coil after passing through the second balance switch in series.
  6. 6. The boost charging circuit of claim 4, wherein the switch-mode unit comprises a third mode switch, the switch-balancing unit comprises a third balancing switch, the second end of the second motor coil is connected with the second end of the third motor coil after being connected in series through the third mode switch, the second end of the third motor coil is also connected with the second end of the first capacitor, and the first end of the second motor coil is connected with the first end of the third motor coil after being connected with the third balancing switch in series.
  7. 7. The boost charging circuit of claim 4, wherein the switch-mode unit comprises a fourth-mode switch, the switch-balance unit comprises 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 single-pole double-throw switch is connected with the second end of the third motor coil after passing through the fourth-mode switch in series, the second end of the third motor coil is also connected with the second end of the first capacitor, the first end of the second motor coil is connected with the first end of the third motor coil after passing through the fourth-balance switch in series, the fixed end of the first single-pole double-throw switch is connected with the second end of the second single-pole double-throw switch, the first contact of the first single-pole double-throw switch is connected with the first end of the first motor coil, the second contact of the first single-pole double-throw switch is connected with the first end of the second motor coil, the first contact of the second single-pole double-throw switch is connected with the first end of the second single-pole double-throw switch, and the first contact of the second single-pole double-throw switch is connected with the second end of the second single-pole double-throw switch.
  8. 8. The boost charging circuit of claim 5 or 6, wherein in the charge-discharge mode, the second end of the first capacitor is connected in series with the third motor coil, the second motor coil, and the first motor coil in sequence, and then is connected to the second end of the first power switch.
  9. 9. The boost charging circuit of claim 7, wherein in the charge-discharge mode, the second end 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 end of the first power switch, the second end of the second power switch, and the second end of the third power switch.
  10. 10. The boost charging method for the electric automobile is characterized by comprising the following steps of: Providing the electric vehicle boost charging circuit of any one of claims 1-9; Before the boosting and charging circuit of the electric automobile boosts and charges the power battery, the motor coil module is switched to the charging and discharging mode through the switch module, the power battery is discharged to charge the charging starting buffer module and the motor coil module for the first time, and the voltage of the charging starting buffer module is maintained through the motor coil module after the first time of charging, so that the voltage of the charging starting buffer module is buffered and lifted to the rated voltage of the direct-current charging port; after the voltage of the charging starting buffer module is buffered and lifted to the rated voltage of the direct current charging port, the direct current charging port is connected with a direct current power supply, the motor coil module is charged for the second time through the direct current power supply, and then the motor coil module and the direct current power supply after the second charging are combined to boost and charge the power battery.

Description

Boost charging circuit and method for electric automobile Technical Field The application relates to the technical field of electric automobiles, in particular to a boost charging circuit and a boost charging method for an electric automobile. Background The dynamic performance and the endurance mileage are key indexes of the electric automobile, and are also the reference points for people to choose to purchase the automobile, and in order to achieve better dynamic performance and longer endurance mileage, high-voltage power batteries have been widely focused. At present, the existing boosting technology can directly charge the high-voltage power battery through the low-voltage direct-current charging port, so that the problem that the low-voltage direct-current charging pile cannot charge the high-voltage power battery is solved. In the related art, a three-phase coil and a power module of a motor are generally multiplexed to charge a power battery, the current output of the motor coil is unbalanced in the charging process, torque is generated in the charging process to cause shaking of a vehicle body, customer experience is affected, and if the inductance of an equivalent inductance of the motor is low, larger current ripple is generated in the charging process, so that the damage risk of other electronic devices is increased. Therefore, how to design a boost charging circuit with a simple structure and balance the three-phase current of the motor is a technical problem to be solved. The comparison document 1 (CN 216851386U) provides a charging current and a vehicle, and the charging circuit comprises a boost circuit, a three-phase motor coil and a three-phase inverter which are sequentially connected, wherein a first end and a second end of the boost circuit are respectively connected to a first end and a second end of a charging port of an electric automobile, a third end of the boost circuit is connected to a connecting point of the three-phase coil of the three-phase motor coil, a fourth end of the boost circuit is connected to a second end of the three-phase inverter, the three-phase coil of the three-phase motor coil is respectively connected to a middle point of a three-phase bridge arm of the three-phase inverter, and the first end and the second end of the three-phase inverter are respectively connected to an anode and a cathode of a power battery. The circuit realizes the charging of the low-voltage direct-current charging port to the high-voltage power battery in a three-phase motor coil parallel connection mode, but the equivalent inductance of the circuit structure is low, current ripple can be generated, and the service life of other electronic devices is influenced. The comparison document 2 (CN 112440761A) provides a driving motor system, a driving motor system control method and an electric automobile, wherein the driving motor system comprises a first switch, a driving motor and a driving motor control loop, the first switch is respectively connected with a direct current charging port and a first bridge arm midpoint in the driving motor control loop, and when the first switch is closed, a second switch of a power battery loop is closed, and a third switch between the direct current charging port and the driving motor control loop is opened, the direct current charging port is connected with the midpoint of the first bridge arm, so that a winding inductance in the driving motor and the driving motor control loop form a booster circuit or a step-down circuit. The power battery is charged in a mode of connecting two phase inductors in the winding inductor in parallel with the third phase inductor in series, but in the charging process, torque can be generated due to unbalanced current flowing through the inductors, so that the experience of customers is affected. Disclosure of Invention In view of the above drawbacks of the prior art, the present invention provides a boost charging circuit and method for an electric vehicle to solve the above technical problems. In order to achieve the above object and other related objects, the present invention provides the following technical solutions. The invention provides a boost charging circuit of an electric automobile, which is used for balancing the current flowing into a motor coil in the boost charging circuit and is characterized by comprising a power module, a motor coil module, a charging starting buffer module and a switch module, wherein the power module is respectively connected with the motor coil module and the charging starting buffer module, the power module is also connected with a power battery, and the charging starting buffer module is also connected with a direct-current charging port; The motor coil module comprises three motor coils, the switch module is connected with the motor coil module, the switch module is used for switching the working mode of the motor coil module, the working mode of the motor coil module comprises