INTRODUCTION
Electric vehicles (EVs) rely on accurate isolation measurement to ensure driver safety and comply with functional safety standards (e.g., ISO 6469-1, ISO 26262). As EV battery voltages rise - often exceeding 800 V - the need for high voltage switching solutions in isolation monitoring circuits is growing.
To meet this need, we are introducing our new VORA1150 1500 V solid-state relay (SSR), which is specifically optimized for isolation resistance measurement in high voltage EV systems.
ISOLATION MEASUREMENT IN EVs
During normal operation or charging, an isolation monitoring device (IMD) checks the resistance between the high voltage battery system and chassis ground. If this isolation degrades or there is a short, the IMD must detect and report it to the battery management system (BMS) to trigger protective measures.
A switching element - typically a solid-state relay - is required to connect the IMD to the HV+ or HV- rails during testing and isolate it afterwards.
WHY USE A SOLID-STATE RELAY?
Compared to electromechanical relays, SSRs are ideal for high voltage, high reliability automotive applications:
- Fast switching for real-time diagnostics
- No mechanical wear, enabling long life even with frequent test cycles
- Silent and arc-free operation, suitable for enclosed environments
- Compact footprint, allowing easy integration into power distribution units (PDUs) or BMS boards
INTRODUCTION OF A NEW 1500 V SSR
Our newly developed VORA1150 solid-state relay is designed specifically for EV isolation measurement applications. Key features include:
- Rated voltage: up to 1500 VDC
- 2.4 kV high pot pulse width: 5 s
- Current handling: up to 50 mA
- Avalanche current: 0.9 mA
- Leakage current: < 100 nA at 1500 V
- Working voltage: up to 1000 VDC
- Fast switching time: < 250 μs
- AEC-Q102 qualified for automotive applications
- Ambient temperature: up to 125 °C
CONCLUSION
The VORA1150 solid-state relay offers the high voltage rating, low leakage, and fast switching needed for safe and reliable isolation monitoring in modern EVs.
Its robust design and Automotive Grade qualification make it a dependable choice for designers looking to meet strict safety standards in high voltage applications.
For more information or design support, contact our applications engineering team at optocoupleranswers@vishay.com, download the full VORA1150 datasheet or Vishay’s whitepaper: https://www.vishay.com/docs/80616/highvoltageisolatiohnmeasurementinevsvora1150.pdf