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Model the dynamics of switched reluctance motor

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.

**Type**Specifies a three-phase 6/4 motor, four-phase 8/6 motor, or a five-phase 10/8 motor.

**Machine model**Select

`Generic model`or`Specific model`. The**Parameters**tab is modified accordingly.

**Stator resistance**The resistance Rs (Ω) of each stator phase winding.

**Inertia**The inertia momentum J (kg.m

^{2}).**Friction**The friction coefficient B (N.m.s).

**Initial speed and position**The initial rotation speed w0 (rad/s) and initial rotor position Theta0 (rad).

**Unaligned inductance**The stator inductance when the rotor is in unaligned position L

_{q}(H).**Aligned inductance**The unsaturated stator inductance when the rotor is in aligned position L

_{d}(H).**Saturated aligned inductance**The saturated stator inductance when the rotor is in aligned position L

_{dsat}(H).**Maximum current**The stator maximum current I

_{m}(A).**Maximum flux linkage**The maximum flux linkage ψ

_{m}(Wb or V.s) corresponding to I_{m}.

**Stator resistance**The resistance Rs (Ω) of each stator phase winding.

**Inertia**The inertia momentum J (kg.m

^{2}).**Friction**The friction coefficient B (N.m.s).

**Initial speed**The initial rotation speed w0 (rad/s) and initial rotor position Theta0 (rad).

**Rotor angle vector**The rotor position Θ (deg) for which the flux linkage is specified.

**Stator current vector**The stator current I

_{s}(A) for which the flux linkage is specified.**Magnetization characteristic**The 2-D lookup table containing the flux linkage as a function of stator current and rotor position.

**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.

**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`.

`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

teta

Rotor position

rad

The `power_SwitchedReluctanceMotorpower_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.

[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," Electrimacs2005 Conference.

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