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Hall Speed and Position

Compute speed and estimate position of rotor by using Hall sensors

Since R2020a

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Libraries:
Motor Control Blockset / Sensor Decoders

Description

The Hall Speed and Position block computes the mechanical speed of the rotor by tracking changes in the Hall state. The block also estimates the electric position of the rotor by using the direction, Hall state, and external counter value inputs.

The block executes periodically after a fixed time interval that the controller algorithm defines.

Examples

Hall Offset Calibration for PMSM

Hall Offset Calibration for PMSM

Calculates the offset between the rotor direct axis (d-axis) and position detected by the Hall sensor. The field-oriented control (FOC) algorithm needs this position offset to run the permanent magnet synchronous motor (PMSM) correctly. To compute the offset, the target model runs the motor in the open-loop condition. The model uses a constant ${V_d}$ (voltage along the stator's d-axis) and a zero ${V_q}$ (voltage along the stator's q-axis) to run the motor (at a low constant speed) by using a position or ramp generator. When the position or ramp value reaches zero, the corresponding rotor position is the offset value for the Hall sensors.

Field-Oriented Control of PMSM Using Hall Sensor

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).

Ports

Input

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The Hall state at current time. For example, these are the possible valid Hall states (where the MSB represents the output of the first Hall sensor connected):

  • 5 - (101)

  • 4 - (100)

  • 6 - (110)

  • 2 - (010)

  • 3 - (011)

  • 1 - (001)

Data Types: uint8 | uint16 | uint32

The external counter value that the block uses to determine the time elapsed between the Hall state change and block execution.

Data Types: uint8 | uint16 | uint32

This value indicates the clock cycles (time) elapsed between two consecutive changes in the Hall state.

Data Types: uint8 | uint16 | uint32

The direction of the rotor spin (either +1 or –1 indicating positive or negative direction of rotation, respectively) during the current Hall state.

Data Types: int8 | int16 | int32

The port value indicates Hall state validity. The value zero indicates that the current or previous Hall state is invalid and that the block cannot calculate speed and position.

The value one indicates that both the current and previous Hall states are valid and that the block can calculate speed and position.

Data Types: uint8 | uint16 | uint32

The port value indicates Hall state change and block execution status. The value one indicates that the Hall state changed, but that the block execution is pending. The value zero indicates that the block has completed executing the last Hall state change.

Data Types: uint8 | uint16 | uint32

Output

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The estimated electrical position of the rotor based on the Expected hall sequence in positive direction parameter and the Direction, HallVal, and CounterValue inputs.

Dependencies

To enable this port, set Block output to either Position or Speed and position.

Data Types: single | double | fixed point

The mechanical speed of the rotor in revolutions per minute. The block calculates this value by tracking the Hall state changes.

The port returns zero if the SpdVal input is zero.

Dependencies

To enable this port, set Block output to either Speed or Speed and position.

Data Types: single | double | fixed point

The port outputs a value of zero (sets the Hall state change flag to zero) indicating that the block has successfully executed speed and position computations for the last Hall state change.

Data Types: single | double | fixed point

Parameters

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General

Select the available block output ports as one of the following values:

  • Speed and position

  • Speed

  • Position

The register size of the external counter. The maximum counter value is 2n-1, where n = counter size.

The clock frequency of the external counter.

The time between two consecutive instances of block execution.

Number of pole pairs available in the motor.

The block does not calculate position for speed below this value.

Rotor angular displacement that represents the interval at which the SpdCnt port value was calculated.

Unit of the angular velocity or mechanical speed (⍵m) output.

Dependencies

To enable this parameter, set Block output to either Speed or Speed and position.

Data type of the rotor angular speed output.

Dependencies

To enable this parameter, set Block output to either Speed or Speed and position.

Position

The Hall sensor sequence that represents the positive direction of rotor spin.

Dependencies

To enable this parameter, set Block output to either Position or Speed and position.

The custom sequence that you can enter to represent rotor spin in the positive direction.

Dependencies

To enable this parameter:

  • Set Block output to either Position or Speed and position.

  • Set Expected hall sequence in positive direction to Custom sequence.

The 1st Order option is less accurate in computing position, but quick. The 2nd Order option is more accurate, but needs more computation time. These equations describe the options:

θ1st Order=θsector+ωt

θ2nd Order=θsector+ωt+12αt2

where:

θ1st Order = Position computed by using 1st order extrapolation.

θ2nd Order = Position computed by using 2nd order extrapolation.

θsector = Sector angle defined by the Hall sensor output.

ω = Angular velocity of the rotor.

α = Angular acceleration of the rotor.

t = Time spent in a sector.

Dependencies

To enable this parameter, set Block output to either Position or Speed and position.

Unit of the angular position output.

Dependencies

To enable this parameter, set Block output to either Position or Speed and position.

The data type for the angular position output.

Dependencies

To enable this parameter, set Block output to either Position or Speed and position.

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™.

Version History

Introduced in R2020a

See Also

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