Q1: What is the core role of film capacitors in the electrical architecture of new energy vehicles?
A: As DC-link capacitors, their primary function is to absorb high bus pulse currents, smooth voltage fluctuations, and protect IGBT/SiC MOSFET switching devices from transient voltage and current surges.
Q2: Why does the 800V platform require higher-performance film capacitors?
A: As the bus voltage increases from 400V to 800V, the requirements for capacitor withstand voltage, ripple current absorption efficiency, and heat dissipation increase significantly. The low ESR and high withstand voltage characteristics of film capacitors are more suitable for high-voltage environments.
Q3: What are the core advantages of film capacitors over electrolytic capacitors in new energy vehicles?
A: They offer higher withstand voltage, lower ESR, are non-polar, and have a longer lifespan. Their resonant frequency is much higher than that of electrolytic capacitors, matching the high-frequency switching requirements of SiC MOSFETs.
Q4: Why do other capacitors easily cause voltage surges in SiC inverters?
A: High ESR and low resonant frequency prevent them from effectively absorbing high-frequency ripple current. When SiC switches at faster speeds, voltage surges increase, potentially damaging the device.
Q5: How do film capacitors help reduce the size of electric drive systems?
A: In the Wolfspeed case study, a 40kW SiC inverter required only eight film capacitors (compared to 22 electrolytic capacitors for silicon-based IGBTs), significantly reducing PCB footprint and weight.
Q6: What new requirements does high switching frequency place on DC-Link capacitors?
A: Lower ESR is required to reduce switching losses, higher resonant frequency is required to suppress high-frequency ripple, and better dv/dt withstand capability is also required.
Q7: How is the lifespan reliability of film capacitors evaluated?
A: It depends on the thermal stability of the material (e.g., polypropylene film) and the heat dissipation design. For example, the YMIN MDP series improves lifespan at high temperatures by optimizing the heat dissipation structure.
Q8: How does the ESR of film capacitors affect system efficiency?
A: Low ESR reduces energy loss during switching, lowers voltage stress, and directly improves inverter efficiency.
Q9: Why are film capacitors more suitable for high-vibration automotive environments?
A: Their solid-state structure, lacking liquid electrolyte, offers superior vibration resistance compared to electrolytic capacitors, and their polarity-free installation makes them more flexible.
Q10: What is the current penetration rate of film capacitors in electric drive inverters?
A: In 2022, the installed capacity of film capacitor-based inverters reached 5.1117 million units, accounting for 88.7% of the total installed capacity of electric control systems. Leading companies such as Tesla and Nidec accounted for 82.9%.
Q11: Why are film capacitors also being used in photovoltaic inverters?
A: The requirements for high reliability and long life are similar to those in automotive applications, and they also need to withstand outdoor temperature fluctuations.
Q12: How does the MDP series address voltage stress issues in SiC circuits?
A: Its low ESR design reduces switching overshoot, improves dv/dt withstand by 30%, and reduces the risk of voltage breakdown.
Q13: How does this series perform at high temperatures?
A: Using high-temperature stable materials and an efficient heat dissipation structure, we ensure a capacity decay rate of less than 5% at 125°C.
Q14: How does the MDP series achieve miniaturization?
A: Innovative thin-film technology increases capacity per unit volume, resulting in a power density exceeding the industry average, enabling compact electric drive designs.
Q15: The initial cost of film capacitors is higher than that of electrolytic capacitors. Do they offer a cost advantage over the lifecycle?
A: Yes. Film capacitors can last up to the life of the vehicle without replacement, while electrolytic capacitors require regular maintenance. In the long run, film capacitors offer lower overall costs.
Post time: Oct-14-2025