What is harmonic control of power inverter

Harmonics are components in a waveform whose frequency is an integer multiple of the fundamental wave. For power inverters, harmonic control is a key aspect to ensure the quality of the output AC waveform.

Causes of harmonic generation: During the operation of the power inverter, the switching of switching devices will cause the output waveform to contain harmonics of different frequencies. These harmonics may cause interference to connected load equipment and power systems, so harmonic control is required to reduce or eliminate these adverse effects.

Pulse Width Modulation (PWM): Pulse width modulation is a primary means of harmonic control. By adjusting the on-off time ratio of the switching device, pulse width modulation can effectively control the harmonic content of the output waveform. The inverter generates a pulse signal and controls the size of the harmonics in the output waveform by changing the width of the pulse.

Multi-level inverter: Traditional inverters usually adopt a two-level structure, that is, the level of the output waveform can only be high or low. However, multilevel inverters employ more levels and can reduce the harmonic content by introducing additional levels into the output waveform. These multi-level technologies include multi-level PWM and multi-level pulse width modulation technology, which can control the output waveform more finely.

Filter Design: Harmonic control can also be achieved by using harmonic filters at the output of the inverter. These filters are typically LC filters that selectively remove specific harmonic components from the output waveform. The filter design needs to be carefully matched to the operating frequency and load requirements of the inverter to ensure effective reduction of harmonics.

Harmonic monitoring and feedback: Advanced power inverter systems are often equipped with harmonic monitoring and feedback control capabilities. By monitoring the actual harmonic content of the output waveform, the system can adjust pulse width modulation and other parameters as needed to control harmonic levels in real time. This closed-loop control system helps adapt to different loads and working conditions and maintain the stability of the output waveform.

Minimum loss control: Harmonic control also needs to consider the loss of the inverter itself. When designing an inverter, engineers need to find a balance that can control harmonics while minimizing energy losses in the inverter itself. This involves optimizing the selection of switching devices, reducing switching frequency and improving heat dissipation systems.