Regulation Switch

Implement torque controller, and switch that selects between torque or speed regulation, for DC motor drives

Library

Simscape / Electrical / Specialized Power Systems / Electric Drives / Fundamental Drive Blocks

Description

The Regulation Switch block consists of a DC machine (wound-field type) torque controller model and a Simulink^® Switch model. The latter is used to select the regulation mode, torque, or speed regulation of the DC drive, as shown in the figure.

The torque controller provides the reference DC current for the machine using the equation

$I^{*} = \frac{T^{*}}{K_{T,}}$

where T* is the torque reference (N.m) and K_T is the torque constant (N.m/A).

A second reference DC current is obtained from the PI speed controller. Depending on the regulation mode, the switch selects between the two DC current references.

The Regulation Switch block has two operating modes depending on whether a current limiter is used. The operating mode with a current limiter allows the lower limit of the reference current to be reduced proportionally to the machine speed. This mode improves the current regulation particularly at low speeds where the back-EMF is not high enough to generate high reverse currents.

Parameters

Drive type

Specify the drive type to use:

Rectifier based (default)
Chopper based

Regulation type

Specify the regulation type to use:

Speed regulation (default)
Torque regulation

Number of quadrants

Specify the number of quadrants to use. The default value is 2.

Mode

Specify the operating mode to use:

Without current limiter (default)
With current limiter

Power (VA)

DC machine nominal power, in volt amperes. The default value is 200*746.

Voltage (V)

DC machine nominal voltage, in volts. The default value is 440

Armature resistance Ra (Ohms)

Armature resistance of the DC machine, in ohms. The default value is 0.0597.

Field-armature mutual inductance Laf (H)

Field-armature mutual inductance of the DC machine, in henry. The default value is 3.320.

Forward voltage Von (V)

Forward voltage of each thyristor in the bridge converter, in volts. The default value is 1.3.

Ron (Ohms)

Internal resistance of each thyristor in the bridge converter, in ohms. The default value is 1e-3.

Current reference limit (pu)

Maximum absolute value (pu) of the armature current reference. The default value is 1.5.

Controller sample time (s)

The controller sampling time, in seconds. The default value is 20e-6.

Network sample time (s)

Simulation time step, in seconds. The default value is 1e-6.

Inputs and Outputs

d_i: Armature current reference error (difference between the reference and the actual machine current).
T*: Torque reference, in Newton-meter.
If: Field current, in amperes.
N*: Speed reference, in rpm.
d_N: Speed error (difference between the speed reference ramp and the actual speed).
la*(pu): Armature current reference, in per-unit.
d: Speed or armature current error.
Ref: Speed reference ramp or torque reference.