Testing of DC link capacitors in New Energy Vehicles (NEVs)
In New Energy Vehicles (NEVs),the engine, battery and engine control technology are among the three core areas of vehicle technology.
The core of the motor control technology is based on a highly efficient motor inverter technology , which requires powerful IGBT modules and suitable DC link capacitors .
The importance of IGBT modules is well known. At the same time, the performance of DC link capacitors should not be underestimated. Therefore, reliable testing of these capacitors is an indispensable and important part of quality control.
Solution details
In practical applications, the high-frequency properties of large capacitors are significantly more complex than in the ideal state.
Conventional automatic component analyzers or impedance analyzers often lack a dedicated four-wire test setup . Furthermore, the internal resistance of the instrument may be too high. This results in an insufficient voltage drop across the load test terminals, which can lead to unstable or inaccurate measurements.
After a warm-up period of approximately 30 minutes for the measuring device, the test device is short-circuited and adjusted to zero.
Next, Cs-Rs (ESR) is selected as the measurement parameter. The capacitor under test is then measured using the test device.
The measurement is performed sequentially at the following frequencies:
- 100 Hz
- 1 kHz
- 10 kHz
- 40 kHz
- 100 kHz
The measurement results are recorded. Subsequently, the two frequencies with the most similar Rs (ESR) values are selected as test parameters.
In the SETUP menu, one of the two selected frequencies is set as the fundamental frequency . Then, the other frequency is set as the test frequency in the main test view, and the measurement function is changed to Cs-Rs-Ls to obtain precise measurements.
List of instruments
- 1 × TH2638