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.