Gate driver integrated instantaneous phase voltage measurement in PWM voltage source inverters

The instantaneous output voltage of power electronic converters can be a very important quantity for the dynamic control of power electronic systems, such as speed transducer-less drives. Dead time effects and semiconductor voltage drop lead to massive distortion in the output voltage and can degrade control performance when the voltage reference is used. Due to the switching nature of power electronic systems, measurement of the output voltage is not a trivial task, especially when knowledge of the terminal voltage without application of any output filters is required. In this paper a gate driver integrated, instantaneous output voltage measurement is proposed that utilizes a combined approach of filtering and oversampling. Based on a theoretical analysis of the sampling and filter induced measurement errors, a mathematical approach to optimize the filter time constant is given. The paper includes test results and description of the hardware system.