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Synchronous Machine d-q Salient Rotor Torque Calculator

Salient-pole synchronous machines possess magnetic asymmetry (direct-axis reactance Xd differs from quadrature-axis reactance Xq).

Per-phase operating AC terminal voltage.

Field-induced internal open-circuit excitation voltage.

Direct-axis synchronous reactance.

Quadrature-axis synchronous reactance.

Rotor displacement angle relative to stator voltage phasor.

Calculated Result
535.1 N·m

Total Shaft Torque

Field Torque

360.2 N·m

Reluctance Torque

174.9 N·m

Reluctance Contribution

32.7%

Calculation Breakdown

  1. Excitation Field Torque (T_field)[3·Vt·Ef / (ω·Xd)] · sin(δ) = 360.2 N·m
  2. Salient Reluctance Torque (T_reluct)[3·Vt² / (2ω)] · (1/Xq - 1/Xd) · sin(2δ) = 174.9 N·m
  3. Total Electromagnetic TorqueT_total = T_field + T_reluct = 535.1 N·m

What Is the Synchronous Machine d-q Salient Rotor Torque Calculator?

In salient-pole synchronous machines, magnetic saliency (Xd > Xq) generates reluctance torque in addition to rotor field excitation torque.

How Does the Synchronous Machine d-q Salient Rotor Torque Calculator Work?

Rotor poles align with minimum magnetic reluctance paths, producing a double-frequency sin(2*delta) torque component.

Synchronous Machine d-q Salient Rotor Torque Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

P = 3 left[ rac{V_t E_f}{X_d} sin(delta) + rac{V_t^2}{2} left( rac{1}{X_q} - rac{1}{X_d} ight) sin(2delta) ight], quad T = rac{P}{omega_s}

Park d-q power-angle equation for salient-pole synchronous electrical machines.

How to Use the Synchronous Machine d-q Salient Rotor Torque Calculator

  1. Input phase terminal voltage, internal back-EMF Ef, reactances Xd and Xq, and power angle delta.

Step-by-Step Example Calculation

Hydroelectric Salient-Pole Generator

Input Values:

terminalVoltageV:230
fieldInducedVoltageEf:260
directReactanceXd:1.4
quadratureReactanceXq:0.85
powerAngleDeltaDeg:32
Worked Steps: Field torque = 368.5 N·m, Reluctance torque = 94.2 N·m (20.4% contribution), Total torque = 462.7 N·m.

Understanding Your Result

Displays total shaft torque in N·m, breakdown between field and reluctance components, and percentage reluctance contribution.

Factors That Affect the Result

  • Reluctance torque allows the machine to maintain stability and deliver mechanical power even under complete loss of DC field excitation.

When Should You Use This Calculator?

  • Hydro generator design, synchronous reluctance motors (SynRM), and permanent magnet assisted reluctance motors (PM-aSynRM).

Assumptions & Limitations

  • Neglects stator armature resistance and magnetic core saturation.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard classical 2-axis Park formulation.

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