SRM Current Controller with PWM Generation

Current controller with internal pulse width modulation for switched reluctance machines

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Libraries:
Simscape / Electrical / Control / SRM Control

Description

The SRM Current Controller with PWM Generation block performs discrete-time proportional-integral (PI) current control for the Switched Reluctance Machine (SRM) block. The block includes pulse width modulation (PWM).

PWM Generation Model

The figure shows the converter structure for an SRM.

As the figure shows, the PWM generation signal is for high side switching devices.

When the control signal is greater than the carrier counter value, the PWM generator outputs 1. Otherwise, it outputs 0.

Equations

To determine the duty cycle, the block implements PI current control in the rotor reference frame in accordance with this equation.

$D=\left(K_p+K_i\frac{T_{s}z}{z-1}\right)\left(I_{s\_ref}-I_s\right)$

Where:

• D is the duty cycle.

• K_p is the proportional gain.

• K_i is the integral gain.

• T_s is the sample time.

• I_{s_ref} is the reference current.

• I_s is the measured current.

To obtain control signals for the three-phases, the block then multiplies the duty cycle with the commutation signals. The resulting three control signals are normalized over the interval [0, 1].

Examples

Switched Reluctance Machine Current Control

Control the current amplitude in a switched reluctance machine (SRM) based electrical drive. A DC voltage source feeds the SRM through a controlled three-arm bridge. An ideal angular velocity source provides the load. The converter turn-on and turn-off angles are maintained constant. A PI-based current controller regulates the current amplitude.

• Open Model

Ports

Input

IsRef — Reference current

scalar

Reference current for control.

Data Types: single | double

Is — Measured current

scalar

Actual current.

Data Types: single | double

Reset — Integrator reset

scalar

External reset signal (rising edge) for the integrator.

Data Types: Boolean

theta — Theta-rotor angle

scalar

Rotor angle in the interval [0, β ].

Data Types: single | double

thetaON — Switch-on angle

scalar

Angle for switching on the phase supply.

Data Types: single | double

thetaOFF — Switch-off angle

scalar

Angle for switching on the phase supply.

Data Types: single | double

Output

G — Gate control

vector

Pulse waveforms that determine switching behavior.

Data Types: single | double

Parameters

Control Parameters

Proportional gain — Controller proportional gain, K_p

1 (default) | positive scalar

Proportional gain, K_p, of the controller.

Integral gain — Integral gain, K_i

5 (default) | positive scalar

Integral gain, K_i, of the controller.

Anti-windup gain — Anti-windup gain, K_aw

1 (default) | positive scalar

Anti-windup gain, K_aw, of the controller.

Sample time (-1 for inherited) — Block sample time

-1 (default) | positive scalar

Time, in s, between consecutive block executions. During execution, the block produces outputs and, if appropriate, updates its internal state. For more information, see What Is Sample Time? and Specify Sample Time.

If this block is inside a triggered subsystem, inherit the sample time by setting this parameter to -1. If this block is in a continuous variable-step model, specify the sample time explicitly using a positive scalar.

PWM Generator

Carrier counter — Carrier counter model

Up (default) | Down | Up-Down

Use the carrier counter strategy to change the initial behavior of the PWM output:

• Up counter — PWM output begins at the start of the on state.

• Down counter — PWM output begins at the start of the off state.

• Up-down counter — PWM output begins in the middle of the on state.

Timer period (s) — PWM timer period

0.001 (default) | positive scalar

Pulse width modulation timer period, T_per, in seconds.

Fundamental sample time (s) — Sample time for PWM generation

0.0001 (default) | positive scalar

Time, in s, between consecutive PWM generator executions. During execution, the block produces PWM output and, if appropriate, updates its internal state. For more information, see What Is Sample Time? and Specify Sample Time.

To ensure adequate resolution in the generated PWM signal, set the fundamental sample time so that $0<T_{s\text{\_}pwm}\le 10T_{per}$, where:

• T_{s_pwm} is the Fundamental sample time (s).

• T_per is the Timer period (s).

References

[1] Saha, N. and S. Panda. "Speed control with torque ripple reduction of switched reluctance motor by Hybrid Many Optimizing Liaison Gravitational Search technique." Engineering Science and Technology. Vol 20 (2017): 909–921.

Extended Capabilities

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

Version History

Introduced in R2018a