Performance analysis of grid connected induction motor using floating H-bridge converter

摘要

Floating capacitor voltage source power electronic converters can be used as series voltage compensators for grid supplied induction motors to improve their steady-state operating performance, namely: actively reducing the motor power losses over its entire load range; lower the motor's operating temperature to improve lifetime expectancy; the voltage supplied to the motor can be used to avoid derating the motor power rating. These features are especially useful when the motor is connected to a grid whose nominal voltage differs from the machine's rated value or that may fluctuate over time (sag or swell). By injecting a voltage in series with the grid supply, floating capacitor converters can set the motor voltage at a fixed desired value, above or below the grid voltage, under transient or continuous steady-state conditions, and over the entire range of the motor load. These features allow the losses in the motor and power electronics to be controlled, e.g. minimized, hence improve the motor and system efficiencies. For applications where frequency control is not required, the proposed power electronics is more energy efficient; hence a viable cost effective solution. Experimental tests are used to compare the proposed system with several alternatives, using performances such as: power losses and efficiency of the motor, power electronics and the system as a whole.