Hall-Effect Rotary Encoder

Four-element Hall-effect rotary encoder

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Libraries:
Simscape / Electrical / Sensors & Transducers

Description

The Hall-Effect Rotary Encoder block models a 360° rotary position sensor using four equally spaced Hall elements under a magnetized, rotating magnet. The elements generate four sinusoidal waveforms.

This figure shows a schematic of the encoder. The hall elements, y_p, y_n, x_p, and x_n, remain in a fixed position while the north and south poles of the magnet rotate at the angle θ.

Equations

These equations describe the voltages between the elements of the rotary encoder:

$$v_x=V_{x0}+A_x\cos (\theta )$$

$$v_y=V_{y0}+A_y\cos (\theta -\frac{\pi }{2}+\beta ),$$

where:

• v_x is the voltage between elements x_p and x_n;

• v_y is the voltage between elements y_p and y_n;

• A_x and A_y are the voltage amplitudes for the x and y axes that reflect the sensitivity mismatch;

• V_x0 and V_y0 are the voltage offsets for the x and y axes;

• β is the quadrature error.

The block uses this equation to decode the angle:

$${\theta }_{out}=\arctan \left(\frac{v_y}{v_x}\right).$$

Variables

To set the priority and initial target values for the block variables before simulation, use the Initial Targets section in the block dialog box or Property Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Nominal values provide a way to specify the expected magnitude of a variable in a model. Using system scaling based on nominal values increases the simulation robustness. You can specify nominal values using different sources, including the Nominal Values section in the block dialog box or Property Inspector. For more information, see System Scaling by Nominal Values.

Examples

Sense Stepper Motor Angle Using Hall Effect Encoder

Detect the angle of a stepper motor using a Hall-Effect Rotary Encoder block.

• Since R2025a
• Open Live Script

Ports

Output

Angle — Rotational angle

physical signal

Physical signal output port for the decoded position in terms of the rotational angle of the magnetic field in the x-y plane.

Dependencies

To enable this port, set the Output interface parameter to Decoded angular position.

Conserving

R — Rotational velocity for the sensor positive probe

mechanical rotational

Mechanical rotational conserving port associated with the sensor positive probe.

C — Rotational velocity for the sensor negative probe

mechanical rotational

Mechanical rotational conserving port associated with the sensor negative (reference) probe.

yp — y-axis positive Hall field

electrical

Electrical conserving port associated with the y-axis positive Hall field.

Dependencies

To enable this port, set the Output interface parameter to Electrical connections.

yn — y-axis negative Hall field

electrical

Electrical conserving port associated with the y-axis negative Hall field.

Dependencies

To enable this port, set the Output interface parameter to Electrical connections.

xp — x-axis positive Hall field

electrical

Electrical conserving port associated with the x-axis positive Hall field.

Dependencies

To enable this port, set the Output interface parameter to Electrical connections.

xn — x-axis negative Hall field

electrical

Electrical conserving port associated with the x-axis negative Hall field.

Dependencies

To enable this port, set the Output interface parameter to Electrical connections.

Parameters

X-axis voltage amplitude — x-axis voltage

2.5 V (default)

X-axis voltage amplitude, in volts.

Y-axis voltage amplitude — y-axis voltage

2.5 V (default)

Y-axis voltage amplitude, in volts.

X-axis voltage offset — x-axis voltage offset

0 V (default)

Potential difference in the electric current flow through the electric conductor in the absence of external magnetic field on the x-axis, in volts.

Y-axis voltage offset — Y-axis voltage offset

0 V (default)

Potential difference in the electric current flow through the electric conductor in the absence of external magnetic field on the y-axis, in volts.

Quadrature error — Quadrature error

0 deg (default)

Amount of quadrature error. Quadrature switching can decrease offset errors.

Output interface — Interface for decoded information

Electrical connections (default) | Decoded angular position

Port interface for decoded information.

Set this parameter to Electrical connections to output the Hall voltages at each sensor. Choosing this option enables the yp, yn, xp, and xn conserving ports.

Set this parameter to Decoded angular position to output the rotational angle of the magnetic field in the x-y plane. Choosing this option enables the Angle physical signal port.

Extended Capabilities

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

Version History

Introduced in R2019b