The core of reducing the switching losses of solar inverters is to optimize the working state and topology design of the switching devices, by reducing the voltage and current overlap during the switching process.
The question you raised is crucial. Switching losses are one of the main sources of inverter efficiency losses, especially in medium to high power scenarios where the impact is significant.
1、 Optimize the selection and parameters of switch devices
Choose devices that are more suitable for high-frequency and low loss operation, and reduce inherent losses at the hardware level.
Prioritize the use of wide bandgap semiconductor devices, such as SiC (silicon carbide) or GaN (gallium nitride) devices. This type of device has fast switching speed, low on resistance, and can reduce switching losses by more than 50% compared to traditional Si (silicon) devices.
Match device parameters with actual operating conditions to avoid redundant losses caused by excessive rated voltage and current of the device. For example, based on the DC side voltage of the inverter, select the voltage withstand level of the device that just covers the requirements.
2、 Improve topology design
Reduce the number of switches or decrease the voltage/current stress during switching through topology optimization.
Adopting soft switching topologies such as LLC resonant topology and phase-shifting full bridge topology. This type of topology switches the switching devices at zero voltage (ZVS) or zero current (ZCS) through resonance, significantly reducing voltage and current overlap during the switching process.
Apply multi-level topologies, such as three-level and five level topologies. The multi-level structure can reduce the voltage stress of a single switching device, allowing the use of devices with lower voltage resistance and loss, while reducing output harmonics.
3、 Optimize control strategy
Adjust the switch timing through algorithms to reduce unnecessary switch actions or optimize the switch process.
Adopting frequency conversion control strategy to adjust the switching frequency according to load changes. Reduce the frequency during light load to reduce the number of switches, and ensure the frequency during heavy load to meet output performance, achieving a balance between loss and performance.
Optimize PWM modulation methods, such as using Space Vector Pulse Width Modulation (SVPWM) instead of traditional Sinusoidal Pulse Width Modulation (SPWM). SVPWM can reduce the number of switching times and improve the utilization of DC voltage, indirectly reducing switching losses.
4、 Improve drive and buffer circuits
Provide better driving conditions for switching devices and suppress voltage and current spikes during the switching process.
Optimize the driving circuit parameters and set the driving voltage and resistance reasonably. Appropriately increasing the driving current can accelerate the switching speed and reduce the switching time; But it is necessary to avoid electromagnetic interference (EMI) problems caused by excessive speed.
Add buffer circuits such as RC buffer and clamp buffer circuits. Buffer circuits can absorb voltage and current spikes generated during the switching process, reducing instantaneous losses of devices while protecting them.
