Torque-maximizing field-weakening control: design, analysis, and parameter selection

Abstract

The torque-maximizing field-weakening control scheme proposed by Kim and Sul is developed further. The performance under imperfect field orientation conditions is investigated, and it is shown that an overestimated-rather than an underestimated-model leakage inductance should be used. A slightly modified algorithm, which offers better robustness and reduced computational complexity, is presented. The importance, for good performance, of combining the scheme with current and speed controllers featuring antiwindup and improved disturbance rejection is emphasized. The dynamics of the resulting closed-loop system are analyzed. Obtained in the process are rules for selection of all controller parameters, allowing tuning without trial-and-error steps. Good performance of the resulting system is verified experimentally.

Influence of Inverter Output Filter on Maximum Torque and Speed of PMSM Drives

“…Consequently, the field-weakening control should be modified for PMSM drives equipped with the LC filter in order to achieve maximum torque operation and good dynamic performance at high speeds. In the following, a fieldweakening method based on voltage control similar to [11] is developed for these drives. The inverter current limitation is added, and the LC filter is taken into account in the determination of the voltage controller gain.…”

“…A field-weakening method for surface-mounted PMSM drives [10] applied a similar voltage-control strategy with a modified input to the PI-controller. The field-weakening control was further developed in [11] for induction motor drives. The PItype voltage controller was replaced with an I-controller to avoid an algebraic loop and to have only one control parameter for the field weakening.…”

“…Various field-weakening control methods have been proposed for PMSM drives. The methods based on voltage control [9]- [11] provide full utilization of the dc-link voltage automatically. In [9], a PI-type voltage controller was used for interior PMSM drives to adjust the voltage reference up to the voltage capability of the inverter.…”

Braking scheme for vector-controlled induction motor drives equipped with diode rectifier without braking resistor

“…The gain (24) equals approximately the gain proposed in [10], but is simpler to implement. According to the eigenvalues, flux dynamics fast enough can be achieved using (21), and a conventional flux controller is not needed.…”

“…Alternatively, the flux reference can be determined based on the error between the reference voltage and the maximum available voltage [9]. A simpler method is obtained by excluding the conventional flux controller [10]; the flux-producing current component is controlled and limited according to The flux dynamics corresponding to the algorithm (21) can be studied using small-signal linearization. The current controller is assumed to be significantly faster than the flux dynamics.…”