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Synchronous Reluctance Machine

Synchronous reluctance machine with sinusoidal flux distribution

  • Library:
  • Simscape / Electrical / Electromechanical / Reluctance & Stepper

Description

The Synchronous Reluctance Machine block represents a synchronous reluctance machine (SynRM) with sinusoidal flux distribution. The figure shows the equivalent electrical circuit for the stator windings.

Motor Construction

The diagram shows the motor construction with a single pole-pair on the rotor. For the axes convention shown, when rotor mechanical angle θr is zero, the a-phase and permanent magnet fluxes are aligned. The block supports a second rotor axis definition for which rotor mechanical angle is defined as the angle between the a-phase magnetic axis and the rotor q-axis.

Equations

The combined voltage across the stator windings is

[vavbvc]=[Rs000Rs000Rs][iaibic]+[dψadtdψbdtdψcdt],

where:

  • va, vb, and vc are the individual phase voltages across the stator windings.

  • Rs is the equivalent resistance of each stator winding.

  • ia, ib, and ic are the currents flowing in the stator windings.

  • ψa, ψb, and ψc are the magnetic fluxes that link each stator winding.

The permanent magnet, excitation winding, and the three stator windings contribute to the flux that links each winding. The total flux is defined as

[ψaψbψc]=[LaaLabLacLbaLbbLbcLcaLcbLcc][iaibic]

where:

  • Laa, Lbb, and Lcc are the self-inductances of the stator windings.

  • Lab, Lac, Lba, Lbc, Lca, and Lcb are the mutual inductances of the stator windings.

The inductances in the stator windings are functions of rotor electrical angle and are defined as

Laa=Ls+Lmcos(2θr),

Lbb=Ls+Lmcos(2(θr2π3)),

Lcc=Ls+Lmcos(2(θr+2π3)),

Lab=Lba=MsLmcos(θr+π6),

Lbc=Lcb=MsLmcos(θr+π62π3),

Lca=Lac=MsLmcos(θr+π6+2π3),

where:

  • Ls is the stator self-inductance per phase. This value is the average self-inductance of each of the stator windings.

  • Lm is the stator inductance fluctuation. This value is the amplitude of the fluctuation in self-inductance and mutual inductance with changing rotor angle.

  • θr is the rotor mechanical angle.

  • Ms is the stator mutual inductance. This value is the average mutual inductance between the stator windings.

Simplified Equations

Applying the Park transformation to the block electrical defining equations produces an expression for torque that is independent of rotor angle.

The Park transformation, P, is defined as

P=23[cosθecos(θe2π3)cos(θe+2π3)sinθesin(θe2π3)sin(θe+2π3)121212],

where θe is the electrical angle. The electrical angle depends on the rotor mechanical angle and the number of pole pairs such that

θe=Nθr,

where:

  • N is the number of pole pairs.

  • θr is the rotor mechanical angle.

Applying the Park transformation to the first two electrical defining equations produces equations that define the behavior of the block:

vd=Rsid+LddiddtNωiqLq,

vq=Rsiq+Lqdiqdt+NωidLd,

v0=Rsi0+L0di0dt,

T=32N(iqidLdidiqLq)

Jdωdt=TTLBmω,

where:

  • id, iq, and i0 are the d-axis, q-axis, and zero-sequence currents, defined by

    [idiqi0]=P[iaibic],

    where ia, ib, and ic are the stator currents.

  • vd, vq, and v0 are the d-axis, q-axis, and zero-sequence currents, defined by

    [vdvqv0]=P[vavbvc],

    where va, vb, and vc are the stator currents.

  • The dq0 inductances are defined, respectively as

    • Ld=Ls+Ms+32Lm

    • Lq=Ls+Ms32Lm

    • L0=Ls2Ms.

  • Rs is the stator resistance per phase.

  • N is the number of rotor pole pairs.

  • T is the rotor torque. For the Synchronous Reluctance Machine block, torque flows from the machine case (block conserving port C) to the machine rotor (block conserving port R).

  • TL is the load torque.

  • Bm is the rotor damping.

  • ω is the rotor mechanical rotational speed.

  • J is the rotor inertia.

Assumptions

The flux distribution is sinusoidal.

Variables

Use the Variables settings to specify the priority and initial target values for the block variables before simulation. For more information, see Set Priority and Initial Target for Block Variables (Simscape).

Ports

Conserving

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Mechanical rotational conserving port associated with the machine rotor.

Mechanical rotational conserving port associated with the machine case.

Expandable three-phase port associated with the stator windings.

Electrical conserving port associated with the neutral phase.

Parameters

expand all

Main

Number of permanent magnet pole pairs on the rotor.

Method for parameterizing the stator.

Dependencies

Selecting Specify Ld, Lq and L0 enables these parameters:

  • Stator d-axis inductance, Ld

  • Stator q-axis inductance, Lq

  • Stator zero-sequence inductance, L0

Selecting Specify Ls, Lm, and Ms enables these parameters:

  • Stator self-inductance per phase, Ls

  • Stator inductance fluctuation, Lm

  • Stator mutual inductance, Ms

Direct-axis inductance of the machine stator.

Dependencies

To enable this parameter, set Stator parameterization to Specify Ld, Lq and L0.

Quadrature-axis inductance of the machine stator.

Dependencies

To enable this parameter, set Stator parameterization to Specify Ld, Lq and L0.

Zero-axis inductance for the machine stator.

Dependencies

To enable this parameter, set Stator parameterization to Specify Ld, Lq and L0.

Average self-inductance of the three stator windings.

Dependencies

To enable this parameter, set Stator parameterization to Specify Ls, Lm, and Ms.

Amplitude of the fluctuation in self-inductance and mutual inductance with the rotor angle.

Dependencies

To enable this parameter, set Stator parameterization to Specify Ls, Lm, and Ms.

Average mutual inductance between the stator windings.

Dependencies

To enable this parameter, set Stator parameterization to Specify Ls, Lm, and Ms.

Resistance of each of the stator windings.

Option to neglect zero-sequence terms. Choices are:

  • Include — Include zero-sequence terms. To prioritize model fidelity, use this default setting. Using this option results in an error for simulations that use the Partitioning solver. For more information, see Increase Simulation Speed Using the Partitioning Solver (Simscape).

  • Exclude — Exclude zero-sequence terms. To prioritize simulation speed for desktop simulation or real-time deployment, select this option.

Dependencies

Selecting Include exposes a zero-sequence parameter in the Impedances settings.

Mechanical

Inertia of the rotor attached to mechanical translational port R.

Rotary damping.

Reference point for the rotor angle measurement. If you select the default value, the rotor and a-phase fluxes are aligned for a zero-rotor angle. Otherwise, an a-phase current generates the maximum torque value for a zero-rotor angle.

References

[1] Kundur, P. Power System Stability and Control. New York, NY: McGraw Hill, 1993.

[2] Anderson, P. M. Analysis of Faulted Power Systems. Hoboken, NJ: Wiley-IEEE Press, 1995.

[3] Moghaddam, R. Synchronous Reluctance Machine (SynRM) in Variable Speed Drives (VSD) Applications - Theoretical and Experimental Reevaluation. KTH School of Electrical Engineering, Stockholm, Sweden, 2011.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Introduced in R2017b