DQ Limiter

Saturate voltages (or current) in the dq reference frame

• Library:

• Motor Control Blockset / Controls / Control Reference

• 

Description

The DQ Limiter block generates saturated values of the input voltages (or current) in the dq reference frame, based on the phase voltage (or current) peak limit of the inverter.

The block accepts reference values of d and q axis voltages (or current) and outputs the corresponding saturated values. The block also provides the unsaturated peak value of the reference dq voltages (or current) to enable field weakening control.

Equations

These equations describe the computation of saturated dq voltage (or current) values by the block.

$$ma{g}^{ref}=\sqrt{{(d^{ref})}^2+{(q^{ref})}^2}$$

When $$ma{g}^{ref}\le D-Q saturation limit$$.

• $d^{sat}=d^{ref}$

• $q^{sat}=q^{ref}$

When $$ma{g}^{ref}>D-Q saturation limit$$.

• $$d^{sat}=\frac{d^{ref}}{\sqrt{{(d^{ref})}^2+{(q^{ref})}^2}}\times D-Q saturation limit$$

• $q^{sat}=\frac{q^{ref}}{\sqrt{{(d^{ref})}^2+{(q^{ref})}^2}}\times D-Q saturation limit$

Ports

Input

dref — Reference d-axis voltage (or current)

scalar

Reference voltage (or current) value along the d-axis of the rotating dq reference frame.

Data Types: single | double | fixed point

qref — Reference q-axis voltage (or current)

scalar

Reference voltage (or current) value along the q-axis of the rotating dq reference frame.

Data Types: single | double | fixed point

Output

dsat — Saturated d-axis voltage (or current)

scalar

Saturated voltage (or current) value along the d-axis of the rotating dq reference frame.

Data Types: single | double | fixed point

qsat — Saturated q-axis voltage (or current)

scalar

Saturated voltage (or current) value along the q-axis of the rotating dq reference frame.

Data Types: single | double | fixed point

magref — Unsaturated peak value of block inputs

scalar

Unsaturated peak value of the input voltages (or current).

Data Types: single | double | fixed point

Parameters

D-Q saturation limit — Phase voltage (or current) peak limit

1 (default) | scalar

The maximum magnitude of the stator phase voltage (or current) that the inverter can supply to the motor.

$$D-Q saturation limit(current)$$ is usually the rated current of the motor. When you work with the Per-Unit system (PU), you should convert the rated current of the motor to Per-Unit value with respect to the base current.

$$D-Q saturation limit \left(voltage\right)$$ is the maximum phase voltage supplied by the inverter. Generally it is $$\frac{V_{\text{dc}}}{\sqrt{3}}$$ for Space Vector PWM and $$\frac{V_{\text{dc}}}{2}$$ for Sinusoidal PWM, where V_dc is the DC link voltage of the inverter.

Note

You can enter either per unit or SI unit voltage (or current) value in this parameter. For optimum performance, we recommend that you provide a per unit value.

Model Examples

Field-Oriented Control of PMSM Using Hall Sensor

Implements the field-oriented control (FOC) technique to control the speed of a three-phase permanent magnet synchronous motor (PMSM). The FOC algorithm requires rotor position feedback, which is obtained by a Hall sensor. For details about FOC, see Field-Oriented Control (FOC).

Extended Capabilities

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

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.