A New Approach to Detect Load Sharing of Dual-Motors Driven and Controlled by a Single Converter using Only Three Current Sensors

Parallel connection of dual-motors by single-inverter is a very cost-effective solution due to the reduced number of power converters and control electronics. Literature shows, that by using four current sensors and two shaft encoders it is possible to calculate the load/flux share of each motor, which can then be fed back to the control scheme in order to improve the performance under load imbalance. In order to further decrease the drive costs, this paper proposes a new sensor configuration using one current sensor less than usual. Its application falls into dual induction motors driven by single-inverter. Therefore, it uses a novel arrangement of only three current sensors, where two are attached to one motor (phase A&B) and the remaining is attached to the second motor (phase C). Signal processing is presented in order to calculate the stator current phasor of the motor with only one current sensor attached. It is proven with experimental measurements taken on a two induction motor configuration (14 kW each) that the proposed sensor configuration and signal processing is able to accurately obtain the torque/load share.