ELECTRIC DRIVE SYSTEM AND OPERATING METHOD

Abstract

A drive system for an electrically driven motor vehicle and a method for operating the drive system, which increases the service life of a power module which is a component of a pulse inverter of the drive system.

Claims

1. A drive system for an electrically driven motor vehicle, comprising: at least one HV battery, at least one electric machine operated with alternating current, and a pulse inverter arranged between the HV battery and the electric machine, wherein the pulse inverter includes a buck converter upstream of a power module, the buck converter is configured to convert an input voltage of the pulse inverter into a lower output voltage which is applied at the input of the power module.

2. The drive system according to claim 1, wherein the buck converter includes a switch, a diode, an inductor and a capacitor.

3. The drive system according to claim 1, wherein the output voltage is 50 to 80% of the input voltage.

4. The drive system according to claim 1, wherein the input voltage is 800 to 1000 Volt.

5. The drive system according to claim 1, wherein the input voltage is 350 to 500 Volt.

6. A method for increasing the service life of a power module in a pulse inverter of a drive system for an electrically driven motor vehicle, comprising: an input voltage of the pulse inverter, which is provided by an HV-battery, is decreased to a lower voltage which is applied at the input of the power module.

7. The method according to claim 6, wherein the input voltage of the pulse inverter is decreased by a buck converter to the lower voltage.

8. The method according to claim 6, wherein the lower voltage is 50 to 80% of the input voltage.

9. The method according to claim 6, wherein the input voltage is 800 to 1000 Volt.

10. The method according to claim 6, wherein the input voltage is 350 to 500 Volt.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The disclosure is represented diagrammatically based on an embodiment in the drawing and is described in greater detail in reference to the drawing. In the drawing:

[0020] FIG. 1 shows a diagrammatic representation of an embodiment of the drive system according to the disclosure.

[0021] FIG. 1 diagrammatically shows an embodiment of the drive system 10 according to the disclosure. The terminals of an HV battery 11 are connected to the inputs of a pulse inverter 12 which comprises a power module 14 and a buck converter 13 which is upstream of the power module 14. The outputs of the power module 14 are connected to an electric machine 15 which is supplied with electric energy by the pulse inverter 12. The buck converter 13 reduces the input voltage U.sub.E which corresponds to the output voltage of the HV battery 11, to a lower output voltage U.sub.A which is applied at the input of the power module 14. Due to the decreased input voltage, the service life of the components of the power module 14 is increased.

[0022] In an example, the input voltage U.sub.E (the output voltage of the HV battery 11) was 850 V. At a switching frequency of 4 kHz, when the voltage U.sub.A applied at the input of the power module 14 was lowered from 850 V to 500 V, an increase of the service life of the semiconductors in the power module 14 by a factor of approximately 2 in comparison to a power module operated at 850 V was observed.