Equivalent loading of induction motors using a new composite power supply with a linear (V/Hz) characteristic

In this paper, a novel variable voltage magnitude variable frequency (VVMVF) composite voltage source is introduced which has a linear (V/Hz) characteristic and can be used for equivalent loading of ac machines, without any need to apply the mechanical load to the test machine's shaft The proposed power supply is composed of a regular constant voltage and frequency source (main source) and an especial PWM inverter (auxiliary source), connected in series using an isolating transformer. As an example, a 1.5 kW single-phase power source of the above type was practically implemented and used for equivalent loading of a single-phase capacitor start induction motor. Simulation and experimental results obtained are in close agreement.