System and method for fault handling in a propulsion system for an electric vehicle

Patent metadata

Field	Value
Publication number	US-11878604-B2
Application number	US-202318108801-A
Country	US
Kind code	B2
Filing date	Feb 13, 2023
Priority date	May 7, 2019
Publication date	Jan 23, 2024
Grant date	Jan 23, 2024

Abstract

A propulsion system for an electric vehicle comprising a high voltage battery unit having a first high voltage battery connected in series with a second high voltage battery, which may also be referred to as a first and second battery bank, and one or more power inverters arranged to connect the battery banks to one or more electric machines. The one or more power inverters and the one or more electric machines are configured to form a first and a second three-phase system. The described architecture incorporating dual battery banks, and dual and/or multiphase inverters and electric machines can provide enhanced redundancy and limp home functionality in cases where a fault or error occurs in the inverter and/or in the electric machine so that a faulty three-phase system can be operated in a safe-state mode.

First claim

What is claimed is:

1. A propulsion system for an electric vehicle, the propulsion system comprising:
a high voltage battery unit having a first high voltage battery connected in series with a second high voltage battery such that a nominal operating voltage of the high voltage battery unit is the sum of a voltage of the first high voltage battery and a voltage of the second high voltage battery;
a first power inverter connected to a first set of three phases of a dual winding three-phase electric machine and a second power inverter connected to a second set of three phases of the dual winding three-phase electric machine, wherein the first three-phase system is formed by the first power inverter and the first set of three phases of the dual winding three-phase electric machine and the second three-phase system is formed by the second power inverter and the second set of three phases of the dual winding three-phase electric machine; and
a propulsion system control unit configured to:
detect a fault of the first or the second three-phase system and operate the first and second three-phase systems in a safe-state mode, wherein, if a back electromotive force, back-EMF, of the faulty three-phase system is higher than the operating voltage of the high voltage battery unit, the propulsion system control unit is configured to control the inverter of the faulty three-phase system to operate in an active short-circuit mode, where transistors of the inverter are kept in a closed state, switching of the transistors is stopped and current and voltage is circulating between the inverter and the electric machine of the faulty three-phase system in a closed short-circuited loop.

2. The propulsion system according to claim 1 , wherein the propulsion system control unit is further configured to operate the vehicle in a limp-home mode where the speed of the vehicle does not exceed a threshold speed.

3. The propulsion system according to claim 1 , wherein, if a back electromotive force, back-EMF, of the faulty three-phase system is lower than or equal to the operating voltage of the high voltage battery unit, the propulsion system control unit is configured to control the inverter of the faulty three-phase system to operate in a safe pulse-off mode, where transistors of the inverter are in an open state and switching of the transistors is stopped.

4. The propulsion system according to claim 1 , wherein the propulsion system control unit is configured to control the non-faulty three-phase system of the first and second three-phase system to provide field weakening current control to reduce the magnetic field in the faulty three-phase system.

5. The propulsion system according to claim 1 , wherein each of the first and second power inverters is configured to operate at a voltage corresponding to a nominal operating voltage of the high voltage battery unit.

6. A propulsion system for an electric vehicle, the propulsion system comprising:
a high voltage battery unit having a first high voltage battery connected in series with a second high voltage battery such that a nominal operating voltage of the high voltage battery unit is the sum of a voltage of the first high voltage battery and a voltage of the second high voltage battery;
a first three-phase power inverter connected to a first set of three phases of a six-phase electric machine and a second three-phase power inverter connected to a second set of three phases of the six-phase electric machine, wherein the first three-phase system is formed by the first three-phase power inverter and of the first set of three phases of the six-phase electric machine and the second three-phase system is formed by the second three-phase power inverter and the second set of three phases of the six-phase electric machine; and
a propulsion system control unit configured to:
detect a fault of the first or the second three-phase system and operate the first and second three-phase systems in a safe-state mode, wherein, if a back electromotive force, back-EMF, of the faulty three-phase system is higher than the operating voltage of the high voltage battery unit, the propulsion system control unit is configured to control the inverter of the faulty three-phase system to operate in an active short-circuit mode, where transistors of the inverter are kept in a closed state, switching of the transistors is stopped and current and voltage is circulating between the inverter and the electric machine of the faulty three-phase system in a closed short-circuited loop.

7. The propulsion system according to claim 6 , wherein the propulsion system control unit is further configured to operate the vehicle in a limp-home mode where the speed of the vehicle does not exceed a threshold speed.

8. The propulsion system according to claim 6 , wherein, if a back electromotive force, back-EMF, of the faulty three-phase system is lower than or equal to the operating voltage of the high voltage battery unit, the propulsion system control unit is configured to control the inverter of the faulty three-phase system to operate in a safe pulse-off mode, where transistors of the inverter are in an open state and switching of the transistors is stopped.

9. The propulsion system according to claim 6 , wherein the propulsion system control unit is configured to control the non-faulty three-phase system of the first and second three-phase system to provide field weakening current control to reduce the magnetic field in the faulty three-phase system.

10. The propulsion system according to claim 6 , wherein each of the first and second power inverters is configured to operate at a voltage corresponding to a nominal operating voltage of the high voltage battery unit.

11. A method for controlling a propulsion system for an electric vehicle having a high voltage battery unit having a first high voltage battery connected in series with a second high voltage battery such that a nominal operating voltage of the high voltage battery unit is the sum of a voltage of the first high voltage battery and a voltage of the second high voltage battery and a first power inverter connected to a first set of three phases of a dual winding three-phase electric machine and a second power inverter connected to a second set of three phases of the dual winding three-phase electric machine, wherein the first three-phase system is formed by the first power inverter and the first set of three phases of the dual winding three-phase electric machine and the second three-phase system is formed by the second power inverter and the second set of three phases of the dual winding three-phase electric machine; the method comprising:
detecting, by a propulsion system control unit, a fault in the first or the second three-phase system; and
operating the first and second three-phase systems in a safe-state mode comprising, if a back electromotive force, back-EMF, of the faulty three-phase system is higher than the operating voltage of the high voltage battery unit, operating the inverter of the faulty three-phase system in an active short-circuit mode, where transistors of the inverter are kept in a closed state, switching of the transistors is stopped and current and voltage is circulating between the inverter and the electric machine of the non-faulty three-phase system in a closed short-circuited loop.

12. The method according to claim 11 , further comprising operating the vehicle in a limp-home mode where the speed of the vehicle does not exceed a threshold speed.

13. The method according to claim 11 , further comprising, if a back electromotive force, back-EMF, of the faulty three-phase system is lower than or equal to the op

Assignees

• Volvo Car Corp

Inventors

• Eriksson Robert
• Sidiropoulos Nikitas

Classifications

• B60L58/20 Primary

  having different nominal voltages · CPC title

• B60L3/003

  relating to inverters · CPC title

• B60L50/66

  Arrangements of batteries · CPC title

• H02M7/537

  using semiconductor devices only, e.g. single switched pulse inverters · CPC title

• H02P25/22

  Multiple windings; Windings for more than three phases · CPC title