DQ Limiter

Saturate voltages (or current) in the dq reference frame

Since R2020a

• 

Libraries:
Motor Control Blockset / Controls / Control Reference
Motor Control Blockset HDL Support / Controls / Control Reference

Description

The DQ Limiter block generates saturated values of the input voltages (or current) in the dq reference frame, depending on the specified saturation limit and the selected method of saturation.

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), which you can use to enable field weakening control.

Note

The block supports a fixed-point data type size up to 128 bits.

Equations

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

For DQ equivalence:

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

When $$ma{g}^{ref}>x_{\max }$$.

• $$d^{sat}=\frac{d^{ref}}{ma{g}^{ref}}\times x_{\max }$$

• $$q^{sat}=\frac{q^{ref}}{ma{g}^{ref}}\times x_{\max }$$

When $$ma{g}^{ref}\le x_{\max }$$.

• $d^{sat}=d^{ref}$

• $q^{sat}=q^{ref}$

Where, x_max is the saturation limit.

When D-axis is prioritized:

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

$$\begin{array}{l}{d}^{sat}=\min \left(\max \left(d^{ref},-x_{\max }\right),x_{\max }\right)\\ q^{sat}=sign\left(q^{ref}\right)\times \min \left(\left|q^{ref}\right|,\left|\sqrt{x_{\max }^2-{\left(d^{sat}\right)}^2}\right|\right)\end{array}$$

Where, x_max is the saturation limit.

When Q-axis is prioritized:

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

$$\begin{array}{l}{q}^{sat}=\min \left(\max \left(q^{ref},-x_{\max }\right),x_{\max }\right)\\ d^{sat}=sign\left(d^{ref}\right)\times \min \left(\left|d^{ref}\right|,\left|\sqrt{x_{\max }^2-{\left(q^{sat}\right)}^2}\right|\right)\end{array}$$

Where, x_max is the saturation limit.

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).

• Open Model

Ports

Input

d^ref — 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

q^ref — 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

satMethod — Saturation technique

scalar

Saturation method that the block uses to initiate saturation. The port accepts one of the following integer values:

• 1 – Prioritize D-axis

• 2 – Prioritize Q-axis

• Any other positive integer – D-Q equivalence method

Dependencies

To enable this port, select Input port for the Saturation method parameter.

Data Types: uint16

satLim — Saturation limit

scalar

Saturation limit value that the block uses to initiate saturation. The port accepts values greater than or equal to 0.

Dependencies

To enable this port, select Input port for the Saturation limit parameter.

Data Types: single | double | fixed point

Output

d^sat — 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

q^sat — 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

mag^ref — Unsaturated peak value of block inputs

scalar

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

Data Types: single | double | fixed point

Parameters

Saturation method — Saturation method selection technique

Specify via dialog (default) | Input port

Select whether the block should use dialog box or input port to specify the saturated method.

Programmatic Use

satMethodInputType

Saturation method selected — Saturation method used by block

D-Q equivalence (default) | Prioritize D axis | Prioritize Q axis

Select the saturation method that the block should use.

Dependencies

To enable this parameter, set Saturation method to Specify via dialog.

Programmatic Use

satMethodSelected

Saturation limit — Saturation limit selection technique

Specify via dialog (default) | Input port

Select whether the block should use dialog box or input port to specify the saturated limit.

Programmatic Use

satLimitInputType

Saturation limit value — Phase voltage (or current) peak limit

1 (default) | scalar

The maximum magnitude of voltage (or current) above which the block outputs are limited.

$$D-Q saturation limit(current)$$ 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 usually 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 (unit of the entered value should be same as that of the d^ref and q^ref inputs). For optimum performance, we recommend that you provide a per unit value.

Dependencies

To enable this parameter, set Saturation limit to Specify via dialog.

Programmatic Use

Vmax

Extended Capabilities

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

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

Supported Block Parameters

For HDL code generation with the DQ Limiter block, set these parameters:

• Set Saturation method to Specify via dialog

• Set Saturation method selected to D-Q equivalence

• Set Saturation limit to Specify via dialog

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
FlattenHierarchy	Remove DQ Limiter block hierarchy from generated HDL code. The default is inherit. See also FlattenHierarchy (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).
SharingFactor	Number of functionally equivalent resources to map to a single shared resource. The default is 0. See also Resource Sharing (HDL Coder).

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

Version History

Introduced in R2020a