150kV/ 300kW High Voltage Supply with IGBT Inverter for Large Industrial Electrostatic Precipitators

With fast switching semiconductor devices like the insulated gate bipolar transistors (IGBT) it is possible to build inverter based high voltage power supplies for electrostatic precipitators. Comparing conventional SCR (Silicon controlled rectifier) based technology the average corona power can be increased significantly to improve the precipitator efficiency. Additionally, during flashovers the fast current control of IGBT power inverters improves the precipitator performance due to fast voltage recovery resulting in further increasing of the peak and average precipitator voltage. In a new approach, the advantages of higher distances up to 400 mm between the discharge and collecting electrodes could be addressed by a voltage up to 150 kV applied to the precipitator. Due to the exact voltage control of the IGBT inverter a smooth DC voltage can be generated and therefore, the overvoltage capability of the system is much lower than it would have to be with a conventional thyristor based high voltage generation system. Thus, the IGBT inverter solution becomes more economical or less expensive to operate than the conventional supply. With the availability of the latest generation of integrated IGBT modules a very compact IGBT inverter has been developed to meet the design requirements by operating at a frequency up to 10 kHz. The new IGBT types have lower saturation voltages than the previous modules resulting in lower power losses. The HV-transformer has been designed with the required rating and stray inductance.