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CN-118418844-B - Energy conversion device and vehicle

CN118418844BCN 118418844 BCN118418844 BCN 118418844BCN-118418844-B

Abstract

The invention discloses an energy conversion device and a vehicle, which comprise a battery pack, an inversion unit, a motor, a first switch unit, a second switch unit and a third switch unit, wherein the inversion unit comprises Y-phase bridge arms, the first end of each phase bridge arm is connected with the positive electrode of a first battery pack, the second end of each phase bridge arm is connected with the negative electrode of a second battery pack, the third end of each phase bridge arm is connected with the first end of a phase coil corresponding to one set of winding, the second end of a multiphase coil of at least one set of winding in the X-phase winding is commonly connected and led out of N wires, the second ends of multiphase coils of the rest sets of windings in the X-phase winding are commonly connected, the phase number of the bridge arms is equal to the phase number of the coils, X is more than or equal to 2, the first switch unit is connected with the N wires, and the second end of the first switch unit is connected with the midpoints of the first battery pack and the second battery pack. The energy conversion device can fully utilize multiple windings of the motor to meet the functional requirements of the vehicle in different states, improves the energy utilization efficiency and improves the system compatibility.

Inventors

  • LING HEPING
  • PAN HUA
  • LI JICHENG
  • ZHANG YUXIN
  • LUO XIANG

Assignees

  • 比亚迪股份有限公司

Dates

Publication Date
20260505
Application Date
20230131

Claims (17)

  1. 1. An energy conversion device, comprising: a battery pack including two first and second battery packs connected in series; The inverter unit comprises Y-phase bridge arms, each phase bridge arm comprises an upper bridge arm and a lower bridge arm, a first end of each phase bridge arm is connected with the positive electrode of the first battery pack, and a second end of each phase bridge arm is connected with the negative electrode of the second battery pack; The motor comprises X sets of windings, wherein the third end of each phase of bridge arm is connected with the first end of one phase of coil corresponding to one set of winding, the second end of the multiphase coil of at least one set of winding in the X sets of windings is connected together and led out of N wires, the second ends of the multiphase coils of the rest sets of windings in the X sets of windings are connected together, the phase number of the bridge arm is equal to the phase number of the coils, X is more than or equal to 2, the phase number of each set of windings is m X , each phase of each set of windings comprises N X coil branches, and N X ≥1,m X is more than or equal to 2, wherein the X sets of windings are used for realizing one or more of motor driving, battery self-heating, battery balancing treatment and direct current charging and discharging; The first end of the first switch unit is connected with the N line, and the second end of the first switch unit is connected with the midpoints of the first battery pack and the second battery pack; The controller is connected with the inversion unit and is configured to control the first switch unit to be conducted in a first state, and obtain a differential mode voltage value corresponding to each phase bridge arm according to a phase current value, a rotor electric angle, a D-axis target current value and a Q-axis target current value on each phase bridge arm; Obtaining a common-mode voltage value corresponding to each phase bridge arm according to the phase current value, the self-heating target current amplitude and the self-heating current frequency on each phase bridge arm; obtaining the corresponding duty ratio of each group of bridge arms according to the differential mode voltage value and the common mode voltage value; And controlling the upper bridge arm and the lower bridge arm of each corresponding phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm so as to realize the coordination of motor driving and self-heating of the battery pack.
  2. 2. The energy conversion device of claim 1, wherein the inverter unit comprises a six-phase leg, the motor comprises 2 sets of windings, each set of windings comprising 2 counter poles, each counter pole comprising three coil branches; in the same set of windings, the first ends of the same-phase coil branches in the three coil branches with 2 opposite poles are commonly connected and are connected with the midpoints of the corresponding bridge arms; the second ends of the three coil branches of each opposite pole are connected together to form a neutral point, and all neutral points of the 2 sets of windings are connected together and lead out N lines.
  3. 3. The energy conversion device of claim 2, further comprising: The controller is connected with the inversion unit and is configured to control the first switch unit to be conducted in a second state, and obtain a differential mode voltage value corresponding to each phase bridge arm according to a phase current value, a rotor electric angle, a D-axis target current value and a Q-axis target current value on each phase bridge arm; Obtaining a common-mode voltage value corresponding to each phase bridge arm according to the phase current value, the self-heating target current amplitude, the self-heating current frequency and the self-heating balanced current on each phase bridge arm; obtaining the corresponding duty ratio of each group of bridge arms according to the differential mode voltage value and the common mode voltage value; and controlling the upper bridge arm and the lower bridge arm of each corresponding phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm so as to realize the coordination of motor driving, self-heating of the battery pack and balanced treatment of the battery pack.
  4. 4. The energy conversion device of claim 2, further comprising: The controller is connected with the inversion unit and is configured to control the first switch unit to be conducted in a third state, and obtain a common mode voltage value corresponding to each phase of bridge arm according to a phase current value, a self-heating target current amplitude, a self-heating current frequency and a self-heating balanced current on each phase of bridge arm; Obtaining the corresponding duty ratio of each group of bridge arms according to the common mode voltage value; And controlling the corresponding upper bridge arm and lower bridge arm of each phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm so as to realize the coordination of self-heating of the battery pack and balanced treatment of the battery pack.
  5. 5. The energy conversion device of claim 2, further comprising: the direct-current charging and discharging port, the positive electrode of which is connected with the first confluence end, and the negative electrode of which is connected with the second confluence end, wherein the first ends of the Y-phase bridge arms are connected together to form the first confluence end, and the second ends of the Y-phase bridge arms are connected together to form the second confluence end; The controller is connected with the inversion unit and is configured to control the first switch unit to be conducted in a fourth state, and obtain a common mode voltage value corresponding to each phase bridge arm according to a phase current value, a self-heating target current amplitude and a self-heating current frequency on each phase bridge arm; Obtaining the corresponding duty ratio of each group of bridge arms according to the common mode voltage value; And controlling the upper bridge arm and the lower bridge arm of each corresponding phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm so as to realize the cooperation of direct current charge and discharge and self-heating of the battery pack.
  6. 6. The energy conversion device of claim 5, wherein the controller is further configured to control the first switching unit to be turned on in a fifth state, and obtain a corresponding common mode voltage value for each phase leg based on a phase current value, a self-heating target current magnitude, a self-heating current frequency, and a self-heating balance current on each phase leg; Obtaining the corresponding duty ratio of each group of bridge arms according to the common mode voltage value; and controlling the corresponding upper bridge arm and lower bridge arm of each phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm so as to realize the coordination of direct current charge and discharge, self-heating of the battery pack and balanced treatment of the battery pack.
  7. 7. The energy conversion device of claim 1, wherein the inverter unit comprises a six-phase leg, The motor includes: A first set of windings, each of the first set of windings comprising 2 counter poles, each counter pole comprising three coil branches, first ends of in-phase coil branches of the three coil branches of the 2 counter poles of the first set of windings being commonly connected and connected with midpoints of corresponding phase leg arms, second ends of the three coil branches of the 2 counter poles of the first set of windings being commonly connected; The second set of windings comprises 2 opposite poles, each opposite pole comprises three coil branches, first ends of in-phase coil branches in the three coil branches of the 2 opposite poles of the second set of windings are connected together and are connected with midpoints of corresponding phase bridge arms, and second ends of the three coil branches of the 2 opposite poles of the second set of windings are connected together and lead out N wires.
  8. 8. The energy conversion device of claim 7, further comprising: And the controller is connected with the inversion unit and is configured to control the first switch unit to be conducted, control the bridge arm corresponding to the first set of windings to drive a vehicle, and control the upper bridge arm and the lower bridge arm of each phase of bridge arm corresponding to the second set of windings to alternately work so as to at least realize self-heating of the battery pack in a sixth state.
  9. 9. The energy conversion device of claim 8, wherein the controller is configured to: obtaining a common-mode voltage value corresponding to each phase bridge arm according to the phase current value, the self-heating target current amplitude and the self-heating current frequency on each phase bridge arm of the second set of windings; obtaining the corresponding duty ratio of each phase bridge arm of the second set of windings according to the common mode voltage value; And controlling the upper bridge arm and the lower bridge arm of each phase of bridge arm corresponding to the second set of windings to alternately work according to the duty ratio corresponding to each phase of bridge arm so as to realize self-heating of the battery pack.
  10. 10. The energy conversion device of claim 8, wherein the controller is configured to: Obtaining a corresponding differential mode voltage value of each phase bridge arm according to the phase current value, the rotor electric angle, the D-axis target current value and the Q-axis target current value of the second set of windings; obtaining a common-mode voltage value corresponding to each phase bridge arm according to the phase current value, the self-heating target current amplitude and the self-heating current frequency on each phase bridge arm of the second set of windings; obtaining the corresponding duty ratio of each phase bridge arm of the second set of windings according to the differential mode voltage value and the common mode voltage value; And controlling the upper bridge arm and the lower bridge arm of each phase of bridge arm to alternately work according to the duty ratio corresponding to each phase of bridge arm of the second set of windings so as to realize the coordination of motor driving and self-heating of the battery pack.
  11. 11. The energy conversion device of claim 7, wherein the controller is configured to control the first switch unit to be turned on, control the bridge arm corresponding to the first set of windings to drive the vehicle, and control the upper bridge arm and the lower bridge arm of each phase of bridge arm corresponding to the second set of windings to alternately operate so as to at least alternately charge and discharge the first battery pack and the second battery pack to achieve self-heating of the battery pack, and so that an absolute value of a difference between a capacitance of the first battery pack and a capacitance of the second battery pack is lower than a preset threshold.
  12. 12. The energy conversion device of claim 11, wherein the controller is configured to: Obtaining a corresponding common-mode voltage value of each phase bridge arm according to the phase current value, the self-heating target current amplitude, the self-heating current frequency and the self-heating balanced current on each phase bridge arm of the second set of windings; obtaining the corresponding duty ratio of each phase bridge arm of the second set of windings according to the common mode voltage value; And controlling the corresponding upper bridge arm and lower bridge arm of each phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm of the second set of windings so as to realize self-heating of the battery pack, wherein the absolute value of the difference value of the capacitance of the first battery pack and the capacitance of the second battery pack is lower than the preset threshold value.
  13. 13. The energy conversion device of claim 11, wherein the controller is configured to: Obtaining a differential mode voltage value corresponding to each phase bridge arm according to the phase current value, the rotor electric angle, the D-axis target current value and the Q-axis target current value on each phase bridge arm of the second set of windings; obtaining a corresponding common-mode voltage value of each phase bridge arm according to the phase current value, the self-heating target current amplitude, the self-heating current frequency and the self-heating balanced current on each phase bridge arm of the second set of windings; obtaining the corresponding duty ratio of each group of bridge arms according to the differential mode voltage value and the common mode voltage value; and controlling the corresponding upper bridge arm and lower bridge arm of each phase of bridge arm to alternately work according to the corresponding duty ratio of each phase of bridge arm of the second set of windings, so that the first battery pack and the second battery pack alternately charge and discharge to realize the coordination of motor driving and self-heating of the battery pack, and the absolute value of the difference value of the capacitance of the first battery pack and the capacitance of the second battery pack is lower than the preset threshold value.
  14. 14. The energy conversion device of claim 7, further comprising: the direct-current charging and discharging port, the positive electrode of which is connected with the first confluence end, and the negative electrode of which is connected with the second confluence end, wherein the first ends of the Y-phase bridge arms are connected together to form the first confluence end, and the second ends of the Y-phase bridge arms are connected together to form the second confluence end; the controller is connected with the inversion unit and is configured to control the first switch unit to be conducted in an eighth state, and obtain a common mode voltage value corresponding to each phase bridge arm according to a phase current value, a self-heating target current amplitude and a self-heating current frequency on each phase bridge arm of the second set of windings; Obtaining the corresponding duty ratio of each group of bridge arms according to the common mode voltage value; And controlling the upper bridge arm and the lower bridge arm of each corresponding phase of bridge arm to alternately work according to the duty ratio corresponding to each phase of bridge arm of the second set of windings so as to realize the cooperation of direct current charge and discharge and self-heating of the battery pack.
  15. 15. The energy conversion device according to any one of claims 1,3, 10, and 13, wherein when obtaining the differential mode voltage value corresponding to each phase leg from the phase current value, the rotor electric angle, the D-axis target current value, and the Q-axis target current value on each phase leg, the controller is specifically configured to: Obtaining bus voltage values at two ends of the battery pack, a torque value of the motor and a rotating speed value of the motor; Obtaining the D-axis target current value and the Q-axis target current value according to the bus voltage value, the torque value of the motor and the rotating speed value of the motor; And obtaining a differential mode voltage value corresponding to each phase bridge arm according to the phase current value, the rotor electric angle, the D-axis target current value and the Q-axis target current value on each phase bridge arm.
  16. 16. The energy conversion device according to any one of claims 1, 5, 9, 10, and 14, wherein when obtaining the corresponding common-mode voltage value of each phase leg from the phase current value, the self-heating target current amplitude, and the self-heating current frequency on each phase leg, the controller is specifically configured to: obtaining N line actual current values according to the phase current values on each phase bridge arm; obtaining N line target current values according to the self-heating target current amplitude and the self-heating current frequency; And obtaining a common-mode voltage value corresponding to each phase of bridge arm according to the N-line actual current value and the N-line target current value.
  17. 17. A vehicle comprising an energy conversion device according to any one of claims 1 to 16.

Description

Energy conversion device and vehicle Technical Field The present invention relates to the field of battery technologies, and in particular, to an energy conversion device and a vehicle. Background With the development and rapid popularization of electric vehicles, many challenges are also faced. The power battery based on lithium ion is widely applied, and the battery is charged or discharged at a proper temperature due to the inherent characteristics of the battery, so that the charging and discharging efficiency of the battery can be improved, the service life of the battery is prolonged, and the charging and discharging capability of the battery at a low temperature is greatly reduced, which affects the practicability of the electric automobile in cold areas. Particularly, for electric vehicles, phenomena such as slow charging speed, shortened endurance, and air conditioning heat dissatisfaction are easy to occur in winter, and low-temperature anxiety is one of key problems which need to be solved urgently, namely how to improve the usability of lithium ions at low temperature, because the low-temperature anxiety is a pain point affecting the user experience in the market process of the electric vehicles. Disclosure of Invention The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, an object of the present invention is to provide an energy conversion device, by which multiple windings of a motor can be fully utilized to meet the functional requirements of a vehicle in different states, thereby improving the energy utilization efficiency and the system compatibility. Another object of the present invention is to provide a vehicle. In order to solve the problems, an embodiment of the first aspect of the invention provides an energy conversion device, which comprises a battery pack, an inversion unit, a motor and a switch unit, wherein the battery pack comprises a first battery pack and a second battery pack which are connected in series, the inversion unit comprises Y-phase bridge arms, each phase bridge arm comprises an upper bridge arm and a lower bridge arm, the first end of each phase bridge arm is connected with the positive pole of the first battery pack, the second end of each phase bridge arm is connected with the negative pole of the second battery pack, the motor comprises X-phase windings, the third end of each phase bridge arm is connected with the first end of a phase coil of a corresponding set of windings, the second end of a multiphase coil of at least one set of windings in the X-phase windings is commonly connected with and led out N wires, the second ends of multiphase coils of the remaining sets of windings in the X-phase windings are commonly connected with the phases of the coils, X is more than or equal to 2, the first end of the first switch unit is connected with the N wires, and the second end of the first switch unit is connected with the middle point of the first battery pack and the second battery pack. According to the energy conversion device provided by the embodiment of the invention, when the first switch unit is conducted, the motor is controlled to output energy by adjusting the duty ratio corresponding to each phase of bridge arm in the inversion unit, so that the energy generated by the motor can be utilized to promote the first battery pack and the second battery pack in the battery pack to alternately charge and discharge to generate heat, the effect of self-heating in the battery pack is achieved, and meanwhile, the energy generated by the motor can be utilized to meet the functional requirements of a vehicle in different states such as driving, charging or discharging states, so that the energy utilization efficiency is improved to the greatest extent and the system compatibility is improved under the condition that the battery low-temperature environment cannot be used is solved. In order to solve the above-described problems, a second aspect of the present invention provides a vehicle including the energy conversion device described in the above-described embodiments. According to the vehicle provided by the embodiment of the invention, the energy conversion device can fully utilize the multiple windings of the motor to meet the functional requirements of the vehicle in different states, so that the energy utilization efficiency is improved, and the system compatibility is improved. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Drawings The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which: FIG. 1 is a schematic circuit diagram of an energy conversion device according to on