Martin Weinmann

Optimum torque control algorithm for wide speed range and four quadrant operation of stator flux oriented induction machine drive without regenerative unit

In general, low power induction motor drive systems are equipped with PWM inverter using a diode rectifier frond-end (has not a regenerative unit) to supply the ac power from the mains to the dc link. The main features of the proposed algorithm are the capability to generate the optimum torque, for four quadrant operation of drive system, over the wide speed range that is fed by PWM inverter equipped with diode rectifier front-end. The algorithm offers the optimum torque capability for the induction motor drive despite significant changes in dc link voltage and machine parameters. The algorithm identifies when the machine enters in the flux weakening region and also adjust the stator flux reference and q-axis current limit according to the dc link voltage and the operating mode. In the motor mode a PI voltage controller generates the stator flux reference and the q-axis current limit, while in the generator mode the power is dissipated in the machine and a PI overvoltage controller increases the stator flux reference limit and limits the q-axis current.

Control of wide speed range PMSM drives with large dc-link variations without regenerative unit utilizing PWM-VSI overmodulation

In this paper the control of wide speed range PMSM (permanent magnet synchronous motor with sinusoidal excitation) is investigated, with particular attention to the low power drives equipped with PWM-VSI (PWM voltage source inverters) without regenerative unit to supply the ac power from the mains to the dc link. An algorithm is proposed to generate the optimum reference current for four quadrant operation of PMSM drive, which is fed by PWM-VSI with diode rectifier front-end. Moreover the algorithm is suitable for operation of the drive in overmodulation range, so the dynamic and steady-state performance of the system can be improved. The algorithm offers also the optimum dynamic and steady-state performance for the PMSM drive despite significant changes in dc link voltage and machine parameters. The proposed control can be easy integrated in the rotor field oriented control with or without mechanical sensors, but also in the scalar control algorithm.