How to maintain EMC stability during EPS emergency switchover?

The emergency switching of EPS after a power outage is a dynamic process that may generate additional transient noise. Measures to maintain EMC stability during this time include:

1. Controlling switching transients: Optimize the drive timing of relays/contactors or static switches (STS) to achieve "break-before-make," avoiding competition and arcing, and providing anti-peak absorption circuits for the coils.

2. Inverter soft start and synchronization: After switching, the inverter should be able to start quickly and smoothly and establish a stable output voltage, avoiding large current surges to the battery and load. Its PWM modulation should gradually increase from a low duty cycle.

3. Maintaining ground continuity: Before and after switching, the system's ground reference point should not be interrupted or abruptly changed, ensuring that the grounding paths of filters and shielding remain effective.

4. Internal power supply maintenance: The auxiliary power supply of the control circuit should remain stable during switching, for example, by drawing power directly from the battery via DC-DC, avoiding control reset.

5. Filter effectiveness: Input and output filters should be able to withstand the transient current and voltage that may occur during switching and maintain their filtering characteristics.