Talk About Those Things About The Three-level Inverter Test

With the continuous development of photovoltaic inverter and UPS technology and the continuous expansion of the market, the requirements for inverter efficiency have been paid more and more attention by manufacturers, and the three-level topology has emerged as the times require. Compared with the traditional two-level structure, the three-level inverter has the advantages of low voltage stress and loss of power devices, good output waveform quality, and high efficiency. It is a new direction for the development of photovoltaic inverter technology.

The working principle of the three-level inverter circuit

Each bridge arm of the three-level structure is composed of 4 IGBTs and 6 diodes. The typical topology shown in the figure below is to analyze the midpoint potential change of the A-phase inverter bridge arm as an example to briefly describe the three-level inverter circuit. working principle.

When the two IGBTs on the upper bridge arm of the A-phase bridge arm are turned on, the potential of point A is the same as that of the positive busbar, which is U, and the stress platform voltage that each IGBT bears is U/2.
When the two IGBTs of the lower bridge arm of the A-phase bridge arm are turned on, the potential of point A is the same as the potential of the negative busbar, which is -U, and the stress platform voltage that each IGBT bears is U/2.
When the second IGBT on the upper bridge arm of the A-phase bridge arm and the bypass clamping diode are turned on, the A-phase inverter bridge is in a freewheeling state, and the potential at point A is the same as the potential at the midpoint of the busbar, which is 0.
The three-level structure has one more level than the two-level structure, which can better approximate the sinusoidal output voltage.

Three-level inverter test solution
Since the birth of the three-level inverter, its PWM control technology and inverter state control have always been the focus of its research. Researchers need high-voltage, high-power, high-performance power test equipment to help them test new products.
The photovoltaic inverter market is constantly developing towards high voltage and high power. The voltage of SP-3U/6U series Power Supply products is up to 2250V, the maximum power of modular design can reach 576kW, and the parallel performance does not decrease. It can be flexibly adapted to the testing needs of different specifications of products of scientific research institutes and R&D laboratories in universities. Good ground pressure resistance ensures safety under high pressure working conditions.