Cause : DC ripple too high comes when the calculated DC ripple level has exceeded the safe threshold. This is commonly caused by loss of one of the mains input phases.

When the DC ripple is too high in an inverter system, it indicates that the output DC voltage is fluctuating or contains significant harmonic content. This can be problematic as it may affect the performance and reliability of the connected equipment.

Here's how you can address high DC ripple in your inverter system:

1. Inspect Input Power: Ensure that the input power to the inverter is stable and free from harmonics. High harmonic content in the input power can contribute to increased DC ripple in the output. Consider using power conditioning equipment such as harmonic filters to mitigate harmonic distortion.

2. Check DC Bus Capacitors: Inspect the DC bus capacitors in the inverter. Capacitors degrade over time and can lose their ability to smooth out the DC voltage effectively, leading to higher ripple. If capacitors are aged or damaged, consider replacing them with new ones.

3. Review Load Conditions: Evaluate the load conditions connected to the inverter. Rapid changes in load or high peak currents can contribute to increased DC ripple. Adjust load conditions or consider using energy storage devices such as capacitors or batteries to buffer load fluctuations.

4. Inspect Output Filters: Check if the inverter is equipped with output filters to reduce harmonic content and ripple. If not, consider installing output filters such as LC filters or active filters to improve the quality of the output voltage.

5. Verify Grounding: Ensure that the inverter and connected equipment are properly grounded. Poor grounding can contribute to increased noise and ripple in the output voltage. Verify that grounding connections are secure and meet electrical safety standards.

6. Adjust PWM Parameters: If the inverter uses pulse-width modulation (PWM) control, review the PWM parameters and adjust them as needed to reduce ripple. Fine-tuning PWM switching frequency and modulation techniques can help improve voltage quality.

7. Monitor Ripple: Utilize monitoring features available in the inverter to measure and analyze DC ripple in real-time. Set up alarms or warnings to alert operators when ripple exceeds acceptable limits.