High power inverter design solution

In large-scale applications such as PV power plants, "high-power" in medium voltage (MV) inverters is characterized by the use of multilevel inverters to enhance efficiency and scalability. These high-power MV systems generally function within a power range of 0.4 MW–40 MW, and in certain applications, can reach up to 100 MW.

One of the application of control systems in high-power inverters is to increase the speed and accuracy in achieving MPPT. Control algorithms continuously examine the input of the inverter and adjust its operational parameters to extract the maximum available power . Another essential factor is computational complexity.

The high-power inverter with a NPC topology, also known as a three-level inverter, is a type of multilevel converter. In contrast to traditional two-level inverters, which have two voltage levels (positive and negative), this inverter has an additional intermediate voltage level known as the neutral point .

With an overall system efficiency close to 98% and a power density of 2.3kW/L, the string inverter reference design demonstrates great performance. In addition, the implementation of an integrated gate-driver solution could lead to cost reductions when considering the total system cost.

In reviewing various PWM techniques in LS-PV-PP high-power inverters, we find that these techniques focus on optimizing the conversion of DC power from solar panels to AC power to inject an appropriate output power into the main grid.

Modulation strategies are crucial in enhancing the performance of high-power inverters, particularly by reducing switching losses, minimizing harmonic distortion, and ensuring compatibility with multilevel inverter architectures . In high-power inverters, modulation techniques are employed to switch the circuit between these states.