High voltage electrical system for a vehicle and method of controlling the system

Patent metadata

Field	Value
Publication number	US-11198376-B2
Application number	US-201916281607-A
Country	US
Kind code	B2
Filing date	Feb 21, 2019
Priority date	Mar 19, 2018
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

A high voltage electrical system for a vehicle, the 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 battery unit is the sum of a voltage of the first high voltage battery and a voltage of the second high voltage battery; a bi-directional high voltage DC/DC-converter connected in parallel with the first high voltage battery and with the second high voltage battery, the DC/DC-converter being arranged to receive a charging voltage from a high voltage inlet or from a propulsion converter connected to an electrical machine; wherein the DC/DC converter is configured to control charging of the first and second high voltage battery to balance a state of charge of the first and second high voltage battery.

First claim

The invention claimed is:

1. A high voltage electrical system for a vehicle, the 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 battery unit is the sum of a voltage of the first high voltage battery and a voltage of the second high voltage battery;
a bi-directional high voltage DC/DC-converter connected in parallel with both the first high voltage battery and the second high voltage battery, the DC/DC-converter being arranged to receive a charging voltage from a high voltage inlet or from a propulsion converter connected to an electrical machine;
wherein the DC/DC converter is configured to control charging of the first and second high voltage battery to balance a state of charge of the first and second high voltage battery when receiving the charging voltage from either the high voltage inlet or from the propulsion converter.

2. The high voltage electrical system according to claim 1 , wherein the DC/DC converter is further configured to, when receiving a charging voltage lower than the nominal operating voltage of the battery unit, operate in a boost mode to charge the high voltage battery unit with a voltage corresponding to the nominal voltage of the high voltage battery unit.

3. The high voltage electrical system according to claim 1 , wherein the DC/DC converter is further configured to, when receiving a charging voltage which is higher than a nominal operating voltage of the first high voltage battery, operate in a buck mode to provide a voltage to the first high voltage battery corresponding to the nominal operating voltage of the first high voltage battery.

4. The high voltage electrical system according to claim 1 , wherein the DC/DC converter is further configured to, when receiving a charging voltage from the propulsion converter, control the current to the first and second high-voltage battery to balance the state-of charge of the first and second high-voltage battery based on an operating voltage of the first and second battery.

5. The system according to claim 1 , further comprising an electrical switch arranged between the high voltage inlet and the first and second high voltage battery and configured to connect the high voltage inlet either to an input terminal of the first high voltage battery and to a first I/O terminal of the DC/DC converter or to an input terminal of the battery unit and to a second I/O terminal of the DC/DC converter.

6. The system according to claim 5 , wherein the switch is configured to connect the high voltage inlet to the input terminal of the first high voltage battery and to the first I/O terminal of the DC/DC converter for a charging voltage corresponding to a nominal operating voltage of the first high voltage battery.

7. The system according to claim 5 , wherein the switch is configured to connect the high voltage inlet to the input terminal of the high voltage battery unit and to the second I/O terminal of the DC/DC converter for a charging voltage corresponding to a nominal operating voltage of the high voltage battery unit.

8. A method for balancing the state-of-charge of a high voltage battery unit for a vehicle having a first high voltage battery connected in series with a second high voltage battery in a high voltage electrical system such that a nominal operating voltage of the battery unit is the sum of a voltage of the first high voltage battery and a voltage of the second high voltage battery, the method comprising:
controlling a bi-directional high voltage DC/DC-converter connected in parallel with both the first high voltage battery and the second high voltage battery to balance a state of charge of the first and second high voltage battery for a received charging voltage from either a high voltage inlet or from a propulsion converter connected to an electrical machine.

9. The method according to claim 8 , further comprising, for a received charging voltage lower than the nominal operating voltage of the battery unit, operating the bi-directional high voltage DC/DC converter in a boost mode to charge the high voltage battery unit with a voltage corresponding to the nominal voltage of the high voltage battery unit.

10. The method according to claim 8 , further comprising, when receiving a charging voltage from the propulsion converter which is higher than a nominal operating voltage of the first high voltage battery, operating the bi-directional high voltage DC/DC converter in a buck mode to provide a voltage to the first high voltage battery corresponding to the nominal operating voltage of the first high voltage battery.

11. The method according to claim 8 , further comprising, when receiving a charging voltage from the propulsion converter, operating the bi-directional high voltage DC/DC converter to control the current to the first and second high-voltage battery to balance the state-of charge of the first and second high-voltage battery based on an operating voltage of the first and second battery.

12. The method according to claim 8 , further comprising operating the bi-directional high voltage DC/DC-converter based on a load connected to either of the first high voltage battery and the second high voltage battery.

13. The method according to claim 8 , further comprising controlling an electrical switch arranged between the high voltage inlet and the first and second high voltage battery to connect the high voltage inlet either to an input terminal of the first high voltage battery and to a first I/O terminal of the bi-directional high voltage DC/DC converter or to an input of the high voltage battery unit and to a second I/O terminal of the bi-directional high voltage DC/DC converter.

14. The method according to claim 13 , further comprising controlling the switch to connect the high voltage inlet to the input terminal of the first high voltage battery and to the first I/O terminal of the bi-directional high voltage DC/DC converter for a charging voltage corresponding to a nominal operating voltage of the first high voltage battery.

15. The method according to claim 13 , further comprising controlling the switch to connect the high voltage inlet to the input terminal of the high voltage battery unit and to the second I/O terminal of the bi-directional high voltage DC/DC converter for a charging voltage corresponding to a nominal operating voltage of the high voltage battery unit.

Assignees

• Volvo Car Corp

Inventors

• Eriksson Robert

Classifications

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H02J7/575

  Parallel/serial switching of connection of batteries to charge or load circuit · CPC title

• H02J7/52

  for charge balancing, e.g. equalisation of charge between batteries · CPC title

• H02J7/50

  acting upon multiple batteries simultaneously or sequentially · CPC title

• B60L50/66 Primary

  Arrangements of batteries · CPC title