Addressing the Harsh Operating Conditions of EPS: YMIN VHT Series Solid-Liquid Hybrid Capacitor High-Reliability Solution

I. Technical Challenges to Capacitor Reliability in EPS Systems

With the increasing prevalence of Electric Power Steering (EPS) systems in passenger vehicles, the requirements for safety, comfort, and electrification compatibility continue to rise. EPS control modules are typically located in the engine compartment or near the steering column, constantly exposed to high temperatures and strong vibrations. Simultaneously, low-speed parking and stationary turning frequently generate high ripple current surges. Traditional liquid electrolytic capacitors are prone to performance degradation under these conditions, becoming a key bottleneck to system reliability.

II. Typical Failure Phenomena and Root Cause Analysis

In vehicle durability testing, some EPS modules exhibited a slight decrease in steering assist torque after tens of thousands of kilometers of complex road conditions and high/low temperature cycles, affecting project acceptance and overall vehicle quality assessment.

Original Solution: Conventional low-impedance liquid electrolytic capacitors

Failure Mode: Electrolyte dries up at high temperatures, ESR increases, filtering and transient discharge capabilities decrease, affecting motor response speed.

Root Cause Analysis:
1. Liquid capacitors rely on ionic conductivity; their ESR is approximately 10 times that of hybrid solid-liquid capacitors, leading to increased module internal resistance and output voltage ripple.

2. Liquid capacitors have a typical lifespan of only 4000 hours at 125℃, which is insufficient to meet the automotive industry’s 10-year or 150,000-kilometer lifespan requirement.

III. YMIN Solution: VHT Series Hybrid Solid-Liquid Capacitors
To address the above issues, YMIN launched the VHT series hybrid solid-liquid capacitors, specifically designed for EPS motor drive modules.

Representative Models

Key performance parameters (typical values ​​at 20℃ / 100kHz)

Core Technology Support

1. Solid-Liquid Hybrid Technology: Combining the advantages of solid conductive polymers and liquid electrolytes, achieving ultra-low ESR and low leakage current, fundamentally preventing electrolyte drying and ensuring ESR stability under high temperatures and long-term use;

2. Vibration-Resistant Structural Design: Optimized internal structure and terminal design to meet stringent mechanical vibration testing requirements;

3. Overload Capacity: Possesses high ripple current withstand capability, capable of handling extreme conditions such as motor stall.

IV. Application Verification: Customer Test Data Comparison

This series of products has been mass-produced and applied in the new generation EPS motor drive modules of several mainstream vehicle platforms and Tier 1 suppliers, mainly for DC bus support and filtering.

Application Scenario Photos

[Scene photos of VHT series solid-liquid hybrid capacitors installed in a customer's EPS module]

Actual test comparison (original liquid capacitor solution vs. YMIN VHT solution)

Conclusion: After switching to the YMIN VHT series, the customer’s EPS module successfully passed all durability verifications, and the power steering attenuation issue did not recur.

V. Certification and Support

The YMIN VHT series solid-liquid hybrid capacitors have passed multiple international authoritative tests and compliance certifications: AEC-Q200 automotive-grade reliability test, ELV vehicle environmental compliance certification, TSCA toxic substance control compliance, RoHS and REACH environmental compliance certifications. These tests and certifications fully verify the product’s long-term reliability under harsh conditions such as temperature cycling, vibration, and high temperature and humidity, making it suitable for steering systems with high requirements for response speed and safety throughout their entire lifecycle.