Inverter, method for configuring an inverter, method for controlling an inverter and corresponding computer program for preventing an overheating of a DC link capacitor

Patent metadata

Field	Value
Publication number	US-12424945-B2
Application number	US-202117454134-A
Country	US
Kind code	B2
Filing date	Nov 9, 2021
Priority date	Nov 11, 2020
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

An inverter having input terminals, output terminals, a DC link capacitor connected to the input terminals and configured to smooth a DC voltage present at the input terminals is disclosed. Controllable switches are connected to the DC link capacitor and to the output terminals, and a control device is also provided. The control device controls the controllable switches such that the controllable switches convert the DC voltage into an AC voltage at the output terminals. The controllable switches are controlled according to a first switching control scheme including a first modulation technique and a first switching frequency, and according to a second switching control scheme in response to a temperature of the DC link capacitor, the second switching control scheme causing less losses in the DC link capacitor than the first switching control scheme.

First claim

The invention claimed is:

1. An inverter comprising:
input terminals;
output terminals;
a DC link capacitor connected to the input terminals and configured to smooth a DC voltage present at the input terminals;
controllable switches connected to the DC link capacitor and to the output terminals; and
a control device configured to:
control the controllable switches such that the controllable switches convert the DC voltage into an AC voltage to be present at the output terminals,
control the controllable switches according to a first switching control scheme including a first modulation technique and a first switching frequency of the controllable switches,
control the controllable switches according to a second switching control scheme in response to a temperature of the DC link capacitor, the second switching control scheme including a second modulation technique and causing less losses in the DC link capacitor than the first switching control scheme,
wherein the first modulation technique incudes a first space vector modulation technique and the second modulation technique includes a second space vector modulation technique that is different from the first space vector modulation technique, and
wherein the first modulation technique is a pulse width modulation (PWM) technique and the second modulation technique is a flat top modulation technique,

control the controllable switches according to the first switching control scheme,
obtain the temperature of the DC link capacitor, and
change controlling the controllable switches from the first switching control scheme that includes the first space vector modulation technique to the second switching control scheme that includes the second space vector modulation technique, in response to the temperature of the DC link capacitor when the temperature of the DC link capacitor exceeds a predefined temperature.

2. The inverter according to claim 1 , wherein the control device is further configured to change controlling the controllable switches from the first switching control scheme to the second switching control scheme in response to the temperature of the DC link capacitor when the temperature of the DC link capacitor exceeds the predefined temperature, and wherein a frequency spectrum of a current flowing through the DC link capacitor during the first switching control scheme differs during the second switching control scheme.

3. The inverter according to claim 1 , wherein the second switching control scheme further includes a second switching frequency for controlling the controllable switches, wherein the second switching frequency is less than the first switching frequency.

4. The inverter according to claim 1 , further comprising at least one temperature sensor coupled to the control device for measuring the temperature of the DC link capacitor.

5. The inverter according to claim 1 , wherein the control device is configured to change the switching control scheme from the first switching control scheme to the second switching control scheme while keeping at least one of a constant current and a constant voltage at an AC terminal or AC terminals.

6. An electric drive comprising: the invertor of claim 1 ; and an electric motor driven by the inverter.

7. A vehicle comprising: wheels; and the electric drive of claim 6 configured to indirectly or directly drive at least one of the wheels.

8. A method for configuring the inverter as claimed in claim 1 , comprising:
determining an equivalent series resistance of the DC link capacitor as a function of a frequency of a DC link capacitor current;
determining a frequency spectrum of the DC link capacitor current for several switching control schemes having at least one of different modulation techniques and different switching frequencies, wherein the different modulation techniques including the first modulation technique and the second modulation technique and the different switching frequencies including the first switching frequency and a second switching frequency;
for each switching control scheme, estimating losses of the DC link capacitor according to the equivalent series resistance and the frequency spectrum of a considered switching control scheme; and
configuring the control device for switching, in response to the temperature of the DC link capacitor, from one of said switching control schemes to another one leading to fewer estimated losses.

9. A non-transitory computer program downloadable from a communication network or recorded on a computer readable medium, comprising instructions for execution of a method for controlling the inverter according to claim 1 , when said program is executed on a computer.

10. The inverter according to claim 1 , wherein the losses in the DC link capacitor depend on a current flowing through the DC link capacitor and an equivalent series resistance of the DC link capacitor.

Assignees

• Valeo Siemens Eautomotive Germany Gmbh

Inventors

• Herold Christian
• Rambetius Alexander

Classifications

• H02M7/5395

  by pulse-width modulation · CPC title

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02M7/5387

  in a bridge configuration · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M1/327 Primary

  against abnormal temperatures · CPC title