Derating Function

Compute derating factor

Since R2020a

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

Description

The Derating Function block generates the derating factor (y) according to the feedback (f_feedback) and maximum limit (f_max) values of the input reference signal.

The derating factor:

Remains equal to one when f_feedback lies between positive and negative values of the Derating threshold. The derating factor varies linearly outside this range according to f_feedback.
Remains equal to zero when the reference signal lies beyond (positive or negative) f_max.

Therefore, you can use the generated derating factor to derate a control signal after the reference signal crosses the specified Derating threshold.

This figure shows the block output when you use a sinusoidal wave as f_feedback.

Equations

The Derating threshold parameter, $x$ indicates the percentage of peak amplitude for the reference signal. The Derating threshold is 0.5 in the block output shown, which results in a threshold value of 2 (for the peak amplitude value of 4 for the sinusoidal reference signal).

$x = [0, 1)$

This equation describes how the block computes the derating factor (y).

$D e r a t i n g f a c t o r (y) = 1 - \frac{f_{f e e d b a c k} - x f_{m a x}}{(1 - x) f_{m a x}}$

Examples

Field-Weakening Control (with MTPA) of PMSM

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

Open Model

Ports

Input

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f_max — Maximum reference signal limit
scalar

Maximum limit of the reference signal value beyond which the derating factor becomes zero.

Data Types: single | double | fixed point

f_feedback — Reference feedback signal
scalar

Reference signal that the block uses to generate the derating factor, which you can then use to derate a control signal.

Data Types: single | double | fixed point

Output

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y — Derating factor
scalar

Derating factor that the block generates based on the feedback and maximum limit values of the reference signal when the signal exceeds the value of the Derating threshold parameter.

Data Types: single | double | fixed point

Parameters

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Derating threshold — Threshold beyond which derating must occur
`0.9` (default) | scalar in the range [0,1)

The reference signal value beyond which the block generates the derating factor.

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.

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).
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).

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

Version History

Introduced in R2020a

Derating Function