Switched Reluctance Motor

Model the dynamics of switched reluctance motor

Library

Simscape / Electrical / Specialized Power Systems / Electrical Machines

Description

The Switched Reluctance Motor (SRM) block represents three most common switched reluctance motors: three-phase 6/4 SRM, four-phase 8/6 SRM, five-phase 10/8 SRM, as shown in the following figure.

The electric part of the motor is represented by a nonlinear model based on the magnetization characteristic composed of several magnetizing curves and on the torque characteristic computed from the magnetization curves. The mechanic part is represented by a state-space model based on inertia moment and viscous friction coefficient.

To be versatile, two models are implemented for the SRM block: specific and generic models. In the specific SRM model, the magnetization characteristic of the motor is provided in a lookup table. The values are obtained by experimental measurement or calculated by finite-element analysis. In the generic model, the magnetization characteristic is calculated using nonlinear functions and readily available parameters.

Parameters

Parameters Tab

Type

Set to 6/4 (default) to specify a three-phase 6/4 motor.

Set to 8/6 to specify a four-phase 8/6 motor.

Set to 10/8 to specify a five-phase 10/8 motor.

Set to 6/4 (60 kw preset model), 8/6 (75 kw preset model), or 10/8 (10 kw preset model) to use a predetermined specific model of a switched reluctance motor. When you use these presets, you do not need to specify the parameters in the Model tab.

Stator resistance

The resistance Rs (Ω) of each stator phase winding. Default is 0.01.

Inertia

The inertia momentum J (kg.m²). Default is 0.0082.

Friction

The friction coefficient B (N.m.s). Default is 0.01.

Initial speed and position

The initial rotation speed w0 (rad/s) and initial rotor position Theta0 (rad). Default is [0 0].

Sample time (−1 for inherited)

Specifies the sample time used by the block. To inherit the sample time specified in the Powergui block, set this parameter to −1. Default is −1.

Model Tab: Generic Model

Machine model: Select Generic model (default) or Specific model. The Model tab is modified accordingly.
Unaligned inductance: The stator inductance when the rotor is in unaligned position L_q (H). Default is 0.67e-3.
Aligned inductance: The unsaturated stator inductance when the rotor is in aligned position L_d (H). Default is 23.6e-3.
Saturated aligned inductance: The saturated stator inductance when the rotor is in aligned position L_dsat (H). Default is 0.15e-3.
Maximum current: The stator maximum current I_m (A). Default is 450.
Maximum flux linkage: The maximum flux linkage ψ_m (Wb or V.s) corresponding to I_m. Default is 0.486.
Plot magnetization curves: If selected, the mask plots the magnetization curves corresponding to the lookup table provided. The magnetization curves represent the machine flux linkage versus the stator current with the rotor position as a parameter. Default is cleared.

Model Tab: Specific Model

Machine model

Select Generic model (default) or Specific model. The Model tab is modified accordingly.

Source

Select Dialog to specify the magnetization characteristic directly in the mask of the block. Select Mat file (default) to specify the magnetization characteristic from data in a MAT file. Default is 'srm64_60kw.mat'.

Magnetization characteristic table

When the Source parameter is set to Dialog, enter the 2-D lookup table containing the flux linkage as a function of stator current and rotor position. Default is 'srm64_60kw.mat'.

When the Source parameter is set to MAT-file, enter the name of the MAT-file that contains the 2-D lookup table flux linkage table, the rotor angle vector, and the stator current vector. The MAT-file must contain these three variable names: FTBL, RotorAngles, and StatorCurrents. Default is 'srm64_60kw.mat'.

Rotor angle vector

The rotor position Θ (deg) for which the flux linkage is specified. The Rotor angle vector parameter is visible only when the Source parameter is set to Dialog. Default is [0 10 20 30 40 45].

Stator current vector

The stator current I_s (A) for which the flux linkage is specified. The stator current vector parameter is visible only when the Source parameter is set to Dialog. Default is [0:25:450].

Plot magnetization curves

If selected, the mask plots the magnetization curves corresponding to the lookup table provided. The magnetization curves represent the machine flux linkage versus the stator current with the rotor position as a parameter. Default is cleared.

Inputs and Outputs

TL

The block input is the mechanical load torque (in N.m). TL is positive in motor operation and negative in generator operation.

m

The block output m is a vector containing several signals. You can demultiplex these signals by using the Bus Selector block from Simulink^® library.

Signal	Definition	Units
V	Stator voltages	V
flux	Flux linkage	V.s
I	Stator currents	A
Te	Electromagnetic torque	N.m
w	Rotor speed	rad/s
theta	Rotor position	rad

Examples

The power_SwitchedReluctanceMotor example illustrates the simulation of the Switched Reluctance Motor.

To develop positive torque, the currents in the phases of a SRM must be to the rotor position. The following figure shows the ideal waveforms (Phase A inductance and current) in a 6/4 SRM. Turn-on and turn-off angles refer to the rotor position where the converter’s power switch is turned on and turned off, respectively.

References

[1] T.J.E. Miller, Switched Reluctance Motors and Their Control, Clarendon Press, Oxford, 1993.

[2] R. Krishnan, Switched Reluctance Motor Drives, CRC Press, 2001.

[3] D.A. Torrey, X.M. Niu, E.J. Unkauf, “Analytical modelling of variable-reluctance machine magnetisation characteristics,” IEE Proceedings - Electric Power Applications, Vol. 142, No. 1, January 1995, pp. 14-22.

[4] H. Le-Huy, P. Brunelle, “Design and Implementation of a Switched Reluctance Motor Generic Model for Simulink SimPowerSystems,” Electrimacs 2005 Conference.

Version History

Introduced before R2006a