ACIM Slip Speed Estimator

Calculate slip speed of AC induction motor

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

Description

The ACIM Slip Speed Estimator block computes the mechanical slip speed (difference between the synchronous speed and rotor speed) of the induction motor.

The block accepts the reference values of d- and q-axis currents and outputs the computed slip speed of the induction motor.

Equations

These equations describe the utilization of the slip speed value for field-oriented control (FOC) of the induction motor:

${\tau }_{\text{r}}= \left(\frac{L_{\text{r}}}{R_r}\right)$

${\omega }_{\text{e\_slip}}= \left(\frac{L_{\text{m}}\cdot i_{\text{sq}}^{ref}}{{\tau }_{\text{r}}\cdot {\lambda }_{\text{rd}}}\right)$

${\omega }_e= {\omega }_r+{\omega }_{e\text{\_}slip}$

$${\theta }_e= {\displaystyle \int {\omega }_e\cdot dt}={\displaystyle \int ({\omega }_r+{\omega }_{e\text{\_}slip})}\cdot dt={\theta }_r+{\theta }_{slip}$$

If we keep the rotor flux as constant and the d-axis is aligned to the rotor flux reference frame, then we can imply:

${\lambda }_{\text{rd}}=L_m{i}_{sd}$

This block implements the preceding calculations as:

${\omega }_{slip}= \left(\frac{1}{p}\right)\left(\frac{1}{{\tau }_{\text{r}}}\right)\left(\frac{i_{sq}^{ref}}{i_{sd}^{ref}}\right)$

For detailed set of equations and assumptions, see Mathematical Model of Induction Motor.

where:

• ${\omega }_{\text{e\_slip}}$ is the electrical slip speed of the rotor (Radians/ sec).

• ${\omega }_{\text{slip}}$ is the mechanical slip speed of the rotor (Radians/ sec).

• ${\omega }_e$ is the electrical speed corresponding to frequency of stator voltages (Radians/ sec).

• $${\omega }_m$$ is the rotor mechanical speed (Radians/ sec).

• ${\omega }_r$ is the rotor electrical speed (Radians/ sec).

• $L_{\text{m}}$ is the magnetizing inductance of the motor (Henry).

• $$R_r$$ is the rotor resistance referred to stator (Ohms).

• $i_{sd}^{ref}$ and $i_{sq}^{ref}$ are the reference stator d- and q-axis currents (Amperes).

• ${\tau }_{\text{r}}$ is the rotor time constant (sec).

• ${\lambda }_{rd}$ is the d-axis flux linkage of the rotor (Weber).

Examples

Field-Oriented Control of Induction Motor Using Speed Sensor

Implements the field-oriented control (FOC) technique to control the speed of a three-phase AC induction motor (ACIM). The FOC algorithm requires rotor speed feedback, which is obtained in this example by using a quadrature encoder sensor. For details about FOC, see Field-Oriented Control.

• Open Model

Ports

Input

I_sd^ref — Reference d-axis stator current

scalar

Reference d-axis stator current.

Data Types: single | double | fixed point

I_sq^ref — Reference q-axis stator current

scalar

Reference q-axis stator current.

Data Types: single | double | fixed point

Output

⍵_m^slip — Slip speed of induction motor

scalar

Mechanical slip speed of the rotor that the block computes.

Data Types: single | double | fixed point

Parameters

Number of pole pairs — Number of pole pairs available in motor

2 (default) | scalar

Number of pole pairs available in the induction motor.

Slip estimation method — Type of motor parameters for slip estimation

Lumped motor parameters (default) | Slip-Based LUT

Since R2026a

Specify the type of motor parameters that the block uses to estimate the slip speed.

• Lumped motor parameters — Generate slip estimates using lumped circuit values.

• Slip-Based LUT — Generate slip estimates using reference slip lookup data.

Rotor resistance (Ohm) — Rotor resistance of motor

1.05 (default) | scalar

Rotor resistance of the induction motor in Ohms.

Dependencies

To enable this parameter, set the Slip estimation method parameter to Lumped motor parameters.

Rotor leakage inductance (H) — Leakage inductance of rotor winding

6.81e-3 (default) | scalar

Inductance due to leakage flux linked to the rotor winding (in Henry).

Dependencies

To enable this parameter, set the Slip estimation method parameter to Lumped motor parameters.

Magnetizing inductance (H) — Magnetizing inductance of induction motor

30e-3 (default) | scalar

Inductance due to the magnetizing flux (in Henry).

Dependencies

To enable this parameter, set the Slip estimation method parameter to Lumped motor parameters.

Output saturation (rpm) — Saturation value for the block output

150 (default) | scalar

Saturation value for the block output (in rpm).

Dependencies

To enable this parameter, set the Slip estimation method parameter to Lumped motor parameters.

D-axis current breakpoint vector, id (A) — d-axis current lookup vector

[0 10 20 30] (default) | vector

Since R2026a

The d-axis current lookup vector to use in the slip speed lookup tables (in Amperes). The vector can have any number of elements.

Dependencies

To enable this parameter, set the Slip estimation method parameter to Slip-Based LUT.

Q-axis current breakpoint vector, id (A) — q-axis current lookup vector

[0 10 20 30 40] (default) | vector

Since R2026a

The q-axis current lookup vector to use in the slip speed lookup tables (in Amperes). The vector can have any number of elements.

Dependencies

To enable this parameter, set the Slip estimation method parameter to Slip-Based LUT.

Slip-based LUT, Slip(id,iq) (electrical speed (rad/s)) — Reference slip lookup data

[0,0,0,0,0;0,0,0,0,0;0,0,0,0,0;0,0,0,0,0] (default) | vector

Since R2026a

Slip lookup table data (in rad/s).

Dependencies

To enable this parameter, set the Slip estimation method parameter to Slip-Based LUT.

Input units — Unit of input values

Per-Unit (PU) (default) | SI Units

Unit of the input values.

Base speed (rpm) — Base speed for per-unit system

1500 (default) | scalar

Base speed (in rpm) for per-unit system.

Dependencies

To enable this parameter, set Input units to Per-Unit (PU).

Base Current (A) — Base current for per-unit system

10 (default) | scalar

Since R2026a

Base current (in Amperes) for per-unit system.

Dependencies

To enable this parameter, set Slip estimation method to Slip-Based LUT and Input units to Per-Unit (PU).

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).
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 R2020b

R2026a: Compute slip speed using new block parameters

The Block Parameters dialog box now includes parameters that enable you to compute slip speed using slip lookup table data.