Control Of Synchronous Reluctance Motor Research Articles

Extended EMF Models of Synchronous Reluctance Motors and Selection of Main Flux Direction

A new mathematical model called an Extended EMF (EEMF) model and a sensorless control method using the concept for PMSMs have proposed by authors, and their availability have been verified by experiments. The purpose of this paper is to apply the EEMF model to sensorless control of synchronous reluctance motors. Since synchronous reluctance motors do not have any permanent magnet, a main flux direction of a motor model can be chosen in two ways. And the difference of the main flux direction leads to two EEMF models. Between two EEMF models, there is some difference from the point of the motor model for sensorless control. We indicate the difference of two EEMF models clearly and derive the difference of the position estimation error caused by deviation of inductance parameters. Moreover, the selection way of EEMF models is discussed. Finally, the selection method is verified by experiments.

A Position-and Velocity-Sensorless Control for Synchronous Reluctance Motor with Disturbance Observer Using High Frequency Voltages and Currents

Synchronous reluctance motors (SynRMs) are characterized by their sturdiness, and several sensorless control methods of SynRMs have been proposed. In their methods, flux is estimated and the rotor position is estimated from the flux. The induced voltages for flux estimation are small at low speed. In this paper, new position estimation method is proposed using the disturbance observer based on high frequency currents. Simulation results show that the proposed system is very useful.

Nonlinear modeling and robust control of synchronous reluctance motors

High speed synchronous reluctance machines can be used in electric drives and power generation systems. This paper develops nonlinear mathematical models for synchronous reluctance motors using the machine ( abc) variables as well as the quadrature, direct and zero ( qd0) variables. Kirchhoff’s and Newton’s laws are used to derive the differential equations that describe the circuitry and torsional–mechanical dynamics. The Park transformation is applied in the model developments to derive the nonlinear differential equations in the rotor reference frame. As complete, highly coupled, nonlinear mathematical models are found, synchronous reluctance motors should be controlled to attain the desired performances in the full torque-speed operating envelope. Hence, controllers must be designed. A robust controller with nonlinear error and state feedback mappings is designed to guarantee robust tracking and to ensure stability, as well as to attain disturbance rejection. The reported straightforward and computationally efficient synthesis procedure is based on the well understood nonlinear feedback mappings and Lyapunov stability theory. Innovative results in modeling, simulation analysis and design are applied to control electric drives driven by three phase synchronous reluctance motors.

Totally invariant state feedback controller for position control of synchronous reluctance motor

A new totally invariant state feedback controller is designed by combining the classical state feedback controller and the variable-structure control (VSC). The combination of these two different control methods has the advantages of both their merits: (1) the easy design of the state feedback and (2) the strong robustness of the VSC. In other words, the system performance can be simply designed for the nominal system by using the classical state feedback, which includes such well-known techniques as the pole placement or the linear quadratic method. Then, VSC is used to ensure the control effect. To demonstrate the effectiveness of the totally invariant state feedback controller, it is applied to the position control of a synchronous reluctance motor. Simulation results are first given. In addition, a prototype hardware system is built and experimentally evaluated.

Sensorless vector control of synchronous reluctance motors with disturbance torque observer

The elimination of the position sensor has been one important requirement in vector control systems because the position sensor spoils the reliability and simplicity of drive systems. Therefore, we present a sensorless vector control technique for synchronous reluctance motors. The rotor position is calculated easily from ds-qs-axes flux linkages which are estimated with a first-order lag compensator. Furthermore, utilizing estimated rotor position as the input of the full-order observer, the rotor speed and disturbance torque are estimated. The proposed sensorless vector control scheme is demonstrated with experimental results.

Optimal position control of synchronous reluctance motor via totally invariant variable structure control

A newly designed optimal control method is presented. The proposed controller is designed via combining classical state feedback control and variable structure control (VSC). This new method fully matches the merits of the easy design of the linear quadratic (LQ) method and the strong robustness of the VSC. The presented optimal control method is demonstrated on a synchronous reluctance motor (SynRM). It is proved that the synchronous reluctance motor can be used in position control by the proposed method, and the designed performance can be easily obtained regardless of the disturbance and uncertainty. A prototype PC-based SynRM control system is built to verify the validity of the proposed scheme.

Position sensorless control of synchronous reluctance motor using high frequency current injection

This paper presents a position sensorless control scheme of a synchronous reluctance motor using high-frequency current injection. The rotor has inherent rotor saliency and its angle is estimated from d and q stator current injection and the appropriate signal demodulation. This scheme gives robust and dynamic estimation of the rotor angle independent of the operating conditions including standstill, light and heavy loading. Experimental results of closed loop speed control of a 3.75 kW axially laminated synchronous reluctance motor are given to verify the proposed scheme.

Efficiency-optimized direct torque control of synchronous reluctance motor using feedback linearization

In this paper, a nonlinear controller capable of high dynamic torque regulation and efficiency optimization of the synchronous reluctance motor (SynRM) using input-output feedback linearization is proposed. The cross-coupling effects in the SynRM model and the torque nonlinearity due to the iron losses in torque-speed characteristics of the SynRM are discussed. The criterion for the efficiency optimization is also introduced and investigated. Since the proposed nonlinear controller directly regulates the torque by selecting the product of d- and q-axes torque currents as one of the output variables, the nonlinear and cross-coupling aspects between the d-and q-axes torque currents and the terminal currents can he eliminated. Hence, the linear torque-speed characteristic can be achieved. In addition, by controlling the power loss-minimizing criterion directly, the proposed controller can optimize the efficiency of the SynRM without deteriorating the dynamics performance.

Low- and zero-speed sensorless control of synchronous reluctance motors

This paper presents a position sensorless vector control able to drive synchronous reluctance motors in any working condition, including low- and zero-speed operations. The proposed control scheme is based on calculating the rotor position from the measurement of an additional high-frequency stator current component and allows a low-cost implementation; moreover, it does not require the knowledge of any motor parameter, nor particular care for motor starting. Simulation and experimental results on a 1.5-kW prototype are presented to evaluate the consistency of the developed technique.

Flux-observer-based high-performance control of synchronous reluctance motors by including cross saturation

A fully digital control scheme for synchronous reluctance motors is presented, based on a particular type of flux observer. This includes a quite accurate magnetic model of the motor, taking into account cross saturation. This model is first described and the practically obtained control performance is then shown, giving evidence to the impact of such a model on the system behavior.

Highly dynamic torque control of synchronous reluctance motor

This paper presents a direct torque controller of a synchronous reluctance motor based on the stator current vector. The stator direct and quadrature voltages which can generate the desired torque are directly calculated from the machine model. A simple model without the core loss and a modified model which includes the core loss are considered in the proposed method. The results show that the fast and highly dynamic torque response can be obtained by the proposed method. The simulation and experimental results are presented to show the validity of the proposed method using the test synchronous reluctance motor.

High-performance control of synchronous reluctance motors

High-performance control of synchronous reluctance motors

Modeling and vector control of synchronous reluctance motors including stator iron loss

The influence of the stator iron loss cannot be neglected since the high-speed operation and precision torque control of AC motors are required. This paper presents the modeling and vector control of synchronous reluctance motors including the stator iron loss. The stator iron loss is modeled by additional windings on the d-q axes, and is introduced as an equivalent iron loss resistance in voltage equations under the assumption that the losses in the stator core are produced in equivalent eddy current windings on d-q axes. The equivalent iron loss resistance is inserted in series with exciting inductance, and the d and q axes interfere with each other through the equivalent iron loss resistance. To achieve vector control, the d-q axis currents are decoupled by nonlinear control voltages. As a result, the instantaneous torque control scheme is equal to that of a DC machine and the torque control is simplified. >