When discussing innovations and improvements in the electrification systems of electric vehicles, the focus is often placed on the core components such as the main control unit and power devices, while auxiliary components like capacitors tend to receive less attention. However, these auxiliary components have a decisive impact on the overall performance of the system. This article will delve into the application of YMIN film capacitors in onboard chargers and explore the selection and application of capacitors in electric vehicles.

Among the various types of capacitors, aluminum electrolytic capacitors have a long history and have occupied a significant position in the field of power electronics. However, with the evolution of technological requirements, the limitations of electrolytic capacitors have become increasingly apparent. As a result, a superior alternative—film capacitors—has emerged.

Compared to electrolytic capacitors, film capacitors offer significant advantages in terms of voltage endurance, low equivalent series resistance (ESR), non-polarity, strong stability, and long lifespan. These characteristics make film capacitors outstanding in simplifying system design, enhancing ripple current capability, and providing more reliable performance under harsh environmental conditions.

Table: Comparative performance advantages of film capacitors and aluminum electrolytic capacitors

By comparing the performance of film capacitors with the application environment of electric vehicles, it is evident that there is a high degree of compatibility between the two. As such, film capacitors are undoubtedly the preferred components in the electrification process of electric vehicles. However, to ensure their suitability for automotive applications, these capacitors must meet stricter automotive standards, such as AEC-Q200, and demonstrate reliable performance under extreme conditions. Based on these requirements, the selection and application of capacitors should adhere to these principles.

01 Film capacitors in OBC

Series	MDP	MDP(H)
Picture
Capacitance （Range）	1μF-500μF	1μF-500μF
Rated Voltage	500Vd.c.-1500Vd.c.	500Vd.c.-1500Vd.c.
Working Temperature	Rated 85℃, maximum temperature 105℃	Maximum temperature 125℃, effective time 150℃
Car regulations	AEC-Q200	AEC-Q200
Customizable	Yes	Yes

An OBC (On-Board Charger) system typically consists of two main components: a rectifier circuit that converts AC mains power into DC, and a DC-DC power converter that generates the required DC voltage for charging. In this process, film capacitors find application in several key areas, including:

● EMI Filtering
● DC-Link
● Output Filtering
● Resonant Tank

02 Application scenarios of film capacitors in OBC

YMIN offers a range of film capacitor products suitable for DC-Link and output filtering applications. Notably, all these products are AEC-Q200 automotive-grade certified. Additionally, YMIN provides specialized models designed for high-temperature and high-humidity (THB) environments, offering developers greater flexibility in component selection.

DC-Link Capacitors

In an OBC system, a DC-Link capacitor is essential for current support and filtering between the rectifier circuit and the DC-DC converter. Its primary function is to absorb high pulse currents on the DC-Link bus, preventing high pulse voltages across the impedance of the DC-Link and protecting the load from overvoltage.

The inherent characteristics of film capacitors—such as high voltage tolerance, large capacitance, and non-polarity—make them ideal for DC-Link filtering applications.

YMIN’s MDP(H) series is an excellent choice for DC-Link capacitors, offering:

Output Filtering Capacitors

To enhance the transient response characteristics of the OBC’s DC output, a large-capacitance, low-ESR output filter capacitor is required. YMIN provides the MDP low-voltage DC-Link film capacitors, which feature:

These products offer outstanding performance, reliability, and adaptability for demanding automotive applications, ensuring efficient and stable OBC operation.

03 Conclusion