High voltage power supply and control technologies for electrostatic precipitators in biomass applications

This paper will show the specific requirements of high voltage power supplies and their control technology related to small size electrostatic precipitators as they will be used in applications of biomass fired furnaces in the near future. Unlike large ESPs, which are installed in heavy industrial plants (e.g. coal fired power stations or steelworks), the small electrostatic precipitators will mainly be used on private properties or small businesses and hence, be operated by people even without any technical background. Therefore, additional requirements need to be considered in the design of the power supply and the control of such a system, that full automatic operation with continuous optimization can be achieved without operator interaction or maintenance. Available power electronic topologies e.g. soft switched, resonant, or pulsed mode will be evaluated and classified by a strength and weakness analysis. Additionally, the collection efficiency is strongly depending on the control performance of the system. Critical operating situations like heat up phases with fairly unstable combustion processes need exact adaption of voltage and current dynamics to achieve the required precipitator performance. Unlike in large electrostatic precipitator plants, flashovers must be merely avoided due to the noise and EMI, which is not acceptable in domestic environments. Fuzzy Logic was tested for the control system to process current and voltage setpoints for the power electronic internal control system. Finally, an example ESP system setup in laboratory state and measured data will show some results to be discussed.