最適レギュレータ理論によるベクトル制御誘導電動機の効率最適化速度制御系構成法

抄録

In this paper, a new synthesis method for an efficiency optimized induction machine speed control system is proposed. Until now, the potential for energy saving in variable frequency induction motor drives has been demonstrated, and the control strategy yielding a reduction in losses have been analyzed. In these methods, losses analysis depend upon the T-type equivalent circuit using the root mean square values. The combination of stator voltage and frequency minimizing the induction motor losses was shown to be a complex function of the operating speed and torque. In this paper, the losses are estimated by an equivalent circuit in α-β axes at synchronously rotating reference frame under steady state.
The controllable losses are described by the stator current proportional to torque and the current component in the direction of the rotor linkage flux. The optimal ratio of these currents for minimizing the controllable losses under a given output is analytically derived.
The efficiency optimization is established by controlling the current ratio to be optimal. The efficiency optimized speed control system which attains maximum efficiency, vector control and zero steady state error for the desired signals simultaneously is proposed by an optimal regulator theory. Considerable improvment on the efficiency at the steady state and quick responses for the desired signal are obtained from simulation results of the efficiency-optimized speed control system.