Disconnection of vehicle electric system using low voltage switch

Abstract

A power system (100, 200) for a vehicle, the power system comprising: a hazardous voltage interlock loop (HVIL) circuit (106) configured to disconnect a high-voltage energy source (102) from a high-voltage system (104); a low-voltage energy source (108) coupled to the HVIL-circuit for supplying operational power to the HVIL-circuit; and a circuit breaker (110) operable to break a connection between the low-voltage energy source and the HVIL circuit, wherein the HVIL-circuit is configured to disconnect the high-voltage energy source from the high-voltage system if the low-voltage energy source is disconnected from the HVIL-circuit.

Claims

1. A power system for a vehicle, the power system comprising: a hazardous voltage interlock loop (HVIL) circuit configured to disconnect a high-voltage energy source from a high-voltage system; a low-voltage energy source coupled to the HVIL-circuit for supplying operational power to the HVIL-circuit; and a circuit breaker arranged to be accessible from an outside of the vehicle and manually operable to break a connection between the low-voltage energy source and the HVIL-circuit, wherein the HVIL-circuit is configured to disconnect the high-voltage energy source from the high-voltage system if the low-voltage energy source is disconnected from the HVIL-circuit.

2. The power system according to claim 1, wherein the circuit breaker is configured to physically break the connection between the low-voltage energy source and the HVIL circuit.

3. The power system according to claim 1, wherein the circuit breaker further comprises a visual identifier configured to enhance the visibility of the circuit breaker in relation to the vehicle.

4. The power system according to claim 1, comprising two circuit breakers arranged at opposing sides of the vehicle, wherein each circuit breaker is configured to break a connection between the low-voltage energy source and the HVIL circuit.

5. The power system according to claim 1, wherein the HVIL-circuit comprises a first contactor arranged to disconnect a positive pole of the high-voltage energy source from the high-voltage system.

6. The power system according to claim 5, wherein the first and/or second contactor is an electromagnetic relay switch.

7. The power system according to claim 1, wherein the HVIL-circuit comprises a second contactor arranged to disconnect a negative pole of the high-voltage energy source from the high-voltage system.

8. The power system according to claim 1, wherein the HVIL-circuit comprises a current source configured to supply a current to functional components of the HVIL-circuit.

9. The power system according to claim 1, wherein the low-voltage energy source is configured to have an operating voltage in the range of 12-48V.

10. The power system according to claim 1, wherein the high-voltage system is configured to have an operating voltage higher than 400V.

11. The power system according to claim 1, wherein the high-voltage system comprises an electric motor for vehicle propulsion.

12. A vehicle comprising a power system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

(2) In the drawings:

(3) FIG. 1 is a schematic illustration of a power system according to an embodiment of the invention;

(4) FIG. 2 is a schematic illustration of a power system according to another embodiment of the invention, and

(5) FIG. 3 is a vehicle comprising a power system according to an embodiment of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

(6) In the present detailed description, various embodiments of a power system according to the present invention are mainly discussed with reference to a power system in a truck. It should however be noted that this by no means limits the scope of the present invention since the described invention is equally applicable in other types of vehicles such as cars, buses and construction vehicles. The described power system may also be used in marine applications such as boats and ships, and in other applications comprising a high-voltage power source.

(7) FIG. 1 schematically illustrates a circuit schematic of a power system 100 for a vehicle. Since the power system 100 relates to safety features of the high-voltage system of the vehicle, it may also be referred to as a safety system, a shut-off system or the like. The power system 100 comprises a hazardous voltage interlock loop (HVIL) circuit 106 configured to disconnect a high-voltage energy source 102 from a high-voltage system 104. The HVIL-circuit comprises an input unit 116, a control unit 118 and a contactor 112 controlled by a contactor drive 120, and the HVIL-circuit is coupled to a low-voltage energy source 108, here in the form of a battery 108, for supplying operational power to the HVIL-circuit 106. The contactor 112 is here illustrated as an electromechanical relay, but it may also be a mechanical circuit breaker. It would in principle be possible to use a solid-state semiconductor switch as contactor. However, a solid-state switch capable of withstanding the high currents of the high-voltage system may not be as cost efficient as other solutions.

(8) The power system further comprises a circuit breaker 110 operable to break a connection between the low-voltage energy source 108 and the HVIL-circuit 106, wherein the HVIL-circuit 106 is configured to disconnect the high-voltage energy source 102 from the high-voltage system 104 if the low-voltage energy source 108 is disconnected from the HVIL-circuit.

(9) A typical HVIL circuit consist of a current source 114, a physical output pin, a return signal pin, here provided by the input unit 116, and a measurement device and control unit 118 that can detect if the loop is closed. When a current source 114 is used, the monitoring device will know what current to expect from a closed loop, hence a very high degree of reliability can be obtained and a deviation in the current provided by the current source can be detected, resulting in that the contactor 112 is opened. The use of a HVIL-circuit in high-voltage vehicle systems is known to the skilled person and will therefore not be described in further detail herein.

(10) In the present example, the circuit breaker 110 is located between the battery 108 and a current source 114 configured to supply a current to the HVIL-circuit. The switch 110 operated by the user may be a signal level device or a mechanical switch.

(11) FIG. 2 schematically illustrates a schematic of power system 200 for a vehicle according to another embodiment of the invention. In FIG. 2, the power system comprises a second contactor 202 arranged to disconnect a negative pole of the high-voltage energy source 102 from the high-voltage system 104. By disconnecting both poles, the safety is increased by lowering the possibility of single-fault situations.

(12) The power system 200 of FIG. 2 also comprises a second circuit breaker 206 for breaking the connection between the battery 108 and the current source 114. The second circuit breaker 206 may for example be arranged on the opposite side of the vehicle compared to the first circuit breaker 110 so that if a vehicle has flipped onto one side, there is always one circuit breaker accessible. In the present example, the first circuit breaker 110 is arranged to break the connection between the positive pole of the battery 108 and the power source and the second circuit breaker 206 is arranged to break the connection between the negative pole of the battery and the power source. However, it would also be possible to have multiple circuit breakers arranged on the same pole. It would also be possible to equip the system with more than two circuit breakers.

(13) FIG. 3 is a vehicle 300 comprising a power system according to any of the aforementioned embodiments. The circuit breaker 110 of the power system 100 is here accessible from the side of the vehicle 300 and the circuit breaker can preferably be manually operated without the use of tools.

(14) It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.