Hi Mohammad
If the DC link voltage is not constant in a grid-connected single-phase inverter when implementing current control, it could be due to a few reasons such as system parameter mismatch, controller design issues or issues with the dc link capacitor.
Here are some of the possible solutions to keep the dc link voltage constant:
- Optimize the DC Link Capacitor: A Capacitor is used to store energy and supply it to loads during power surges. Capacitors come with ratings, choosing a capacitor with a high rating can ensure the voltage remains constant despite the fluctuations.
- Modify the Control Algorithms: Implement feedforward control (in which the value of input is computed based on the conditional relationship of states) to adjust the dc link voltage. Modifying the control algorithms of the inverter through proportional or Integral controllers can help with current and voltage regulation.
- Increase the boost converter power: The boost converter increases the voltage to a higher level and tries to regulate it using the MPPT algorithm. If the input power supply is weak or the boost converter design is poor, it can cause a problem with voltage regulation. You can increase the power input into the boost converter or modify the design.
- Optimize the Circuit Components and Electrical Parameters: Optimize the circuit components' and controller's electrical parameters such as control mode selection, half-beat frequency modulation, and carrier waveform optimization. This will help to minimize the deviation of the voltage and keep it close to its reference value.
However please note that It is important to note that before making any changes to the inverter and its control, you should assess the system's overall safety.
For any further query on this, do comment.
Hope it Helps
