Predictive Control of Parallel Induction Motors Fed by Single Inverter with Common Current Sensors

Abstract

Dual-motor single inverter drives reduce installation space, weight and overall costs. On the other hand, complexity of the control increases significantly, since the condition on each electric motor can vary in a wide range. Today, majority of control algorithms are based on field oriented control. The consequences of parallel connection of induction motors are addressed by prioritizing model of the motors with higher relevance to the control. The control problem becomes even more complicated when the drive is equipped with common sensors measuring phase currents at the inverter output only. Performance of the field oriented control strongly depends on the model with full state, which is not available trough measurement, due to the lack of current sensor for particular motors. We propose to simplify the model of dual motor drive and use it with finite control set model predictive control (FCS-MPC). The steady state solution of the control problem is used to improve the control performance. This is achieved as an additional term in the cost function. The algorithm is designed with respect to maximum simplicity and its properties are tested in simulations as well as in a real experiment on the laboratory prototype of a dual induction motor drive of rated power $2\mathrm{x}4.5$ kW.