(MENAFN- Market Press Release) October 20, 2025 9:40 pm - Ymin MDP Series DC-Link Film Capacitors: A Key Choice for Improving New Energy System Stability

DC-Link capacitors serve as a stabilizer for the system's DC bus. Yongming's MDP series film capacitors have become an industry mainstream due to their excellent performance. The following are key FAQs to assist with industry applications.

Q1: What are DC-Link capacitors? What core role do they play in new energy systems?

DC-Link capacitors are DC support capacitors, connecting the DC bus between the rectifier and the inverter. Their core functions include stabilizing the bus voltage to prevent fluctuations from impacting power devices; absorbing high-frequency ripple current to ensure current stability; and suppressing switching spikes in devices like IGBTs, providing clean DC power to the inverter. They are the ballast for system efficiency and reliability.

Q2: Why are film capacitors, rather than electrolytic capacitors, commonly chosen for DC-Link capacitors in new energy systems (such as automotive electric drives and photovoltaic inverters)?

The demand for high reliability, high power density, and long life in new energy systems makes film capacitors the preferred choice for DC-Link capacitors. Advantages include polarity-free compatibility with complex circuits, high ripple current resistance, low ESL/ESR, no dry-out issues, and a long lifespan, making them a perfect match for applications such as automotive electric drives and photovoltaic inverters. Electrolytic capacitors have significant shortcomings in ripple current resistance, high temperature resistance, and lifespan, making them difficult to adapt.

Q3: What are the main technical features of the Yongming MDP series DC-Link film capacitors?

Core technical features of the Yongming MDP series: Using a metallized polypropylene film dielectric, they achieve low loss, high insulation resistance, and excellent self-healing properties. They offer high withstand voltage and ripple current in a compact design, while structural optimization reduces ESL. They can easily handle the high voltages, high currents, and complex environmental stresses of new energy systems.

Q4: What specific new energy application scenarios are the MDP series film capacitors suitable for?

The MDP series' performance is fully compatible with core new energy applications: in the new energy vehicle sector, it is suitable for electric drive inverters, OBCs, and DC-DC converters; in the new energy power generation and energy storage sector, it is used in photovoltaic inverters, ESSs, wind turbine converters, and other applications. Its core function is to stabilize the DC bus voltage.

Q5: How do I select the appropriate MDP series capacitor capacity and voltage rating for an electric drive inverter?

Electric drive inverter selection requires calculations based on system parameters and a safety margin: 1. Clarify basic parameters such as bus voltage, maximum ripple current, and voltage ripple rate; 2. Allow 1.2-1.5 times the voltage level for overvoltage protection; 3. Ensure the capacity meets voltage ripple suppression requirements, and the rated ripple current must be greater than the system's actual maximum.

Q6: What exactly does the "self-healing property" of a capacitor mean? How does it contribute to system reliability?

Self-healing is the core reliability of film capacitors: when the dielectric breaks down locally, the instantaneous high temperature at the breakdown point causes the surrounding metallized electrodes to evaporate, quickly restoring insulation. This property prevents local defects from leading to overall failure, significantly reducing the risk of system failure and improving operational reliability and safety.

Q7: In design, how should capacitors be used in parallel to increase capacity or current?

When connecting capacitors in parallel, ensure current balance: 1. Ensure that all parallel capacitors have the same voltage rating; 2. Prioritize capacitors from the same batch with consistent parameters; 3. Use symmetrical, low-inductance connections in the PCB layout to avoid current overload caused by uneven parasitic parameters.

Q8: What is equivalent series inductance (ESL)? Why is low ESL crucial for high-frequency inverter systems?

ESL is the inherent parasitic inductance of capacitors, and its impact is significant in high-frequency scenarios: high ESL can cause high-frequency oscillation, voltage overshoot (increased device stress), and EMI interference (impacting compatibility). The Yongming MDP series achieves low ESL through optimized electrodes and terminals, making it suitable for high-frequency inverter requirements.

Q9: What factors determine the rated ripple current capability of a film capacitor? How is its temperature rise evaluated?

The rated ripple current is primarily determined by ESR: current flowing through the ESR generates heat, and lower ESR increases ripple resistance. Temperature rise assessment requires actual measurement: the core temperature at maximum ripple current must be within the rated range (commonly measured with a thermal imager). Exceeding the temperature rise limit will accelerate aging.

Q10: When installing DC-Link capacitors, what precautions should be taken regarding the mechanical structure and electrical connections?

Key installation points: Mechanically, they must be securely fastened (especially in vibration environments to prevent terminals from loosening); electrically, busbars and cables must be kept short and wide to reduce parasitic inductance, and installation torque must be controlled to prevent terminal damage or poor contact.

Q11: What key tests can be used to verify the performance of DC-Link capacitors in a system?

Core tests to ensure capacitor performance: 1. High-voltage insulation test (Hi-Pot) to verify insulation and leakage protection; 2. Measurement of capacitance/ESR and other parameters; 3. Ripple current and temperature rise test to simulate operating conditions; 4. System-level surge and overvoltage test to verify extreme withstand capabilities.

Q12: What are the common failure modes of film capacitors? How does the MDP series mitigate these risks?

Common failure modes of film capacitors: overvoltage breakdown, overheating, and terminal damage. The MDP series offers targeted solutions: high-voltage withstand design to prevent overvoltage; low ESR to reduce heat and slow aging; reinforced terminals to resist mechanical damage; and self-healing properties to reduce the risk of localized defects.

Q13: How can capacitor connection reliability be ensured in highly vibrating environments (such as those in vehicles)?

To ensure reliability in highly vibrating environments (such as those in vehicles), the MDP series utilizes a reinforced structure on the device side; on the system side, anti-loosening fasteners (such as spring washers) and thermal adhesive are used for fixation, and the support structure is optimized to avoid resonant frequency points.

Q14: What causes "capacitance fade" in film capacitors? Is it a sudden failure or a gradual aging process?

Capacitance fade is caused by trace electrode evaporation during the self-healing process and is a slow, gradual aging process, unlike the sudden failure of electrolytic capacitors due to electrolyte depletion. Its predictable decay pattern facilitates system lifecycle management and maintenance planning.

Q15: What new challenges does future new energy systems pose to DC-Link capacitors?

Three major challenges for future DC-Link capacitors: higher power density, higher switching frequencies (such as SiC/GaN applications), and more extreme environments. Yongming's response: developing products with compact size, low ESL/ESR, and high temperature resistance.

Yongming's MDP series leverages technological innovation to build a solid foundation for new energy systems. The company will continue developing products to meet the needs of industry upgrades and support the high-quality development of new energy.

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