Hall Speed and Position

Compute speed and estimate position of rotor by using Hall sensors

• Library:

• 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.

Ports

Input

HallVal — Current Hall sensor output state

scalar

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: single | double | fixed point

Cnt — External counter value

scalar

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

Data Types: single | double | fixed point

SpdCnt — Count at Hall state change

scalar

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

Data Types: single | double | fixed point

Dir — Rotor spin direction during current Hall state

scalar

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: single | double | fixed point

SpdVal — Validity of current and previous Hall states and speed calculation

scalar

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: single | double | fixed point

HallChng — Value of Hall state change flag

scalar

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: single | double | fixed point

Output

θe — Electrical position of rotor

scalar

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

⍵m — Mechanical speed of rotor

scalar

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

HallChngRst — Resets Hall state change flag to zero

scalar

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

General

Block output — Select output ports

Speed and position (default) | Speed | Position

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

• Speed and position

• Speed

• Position

Counter size — Size of external counter register

16 bits (default) | 8 bits | 32 bits

The register size of the external counter. The maximum counter value is $${\text{2}}^{\text{n}}\text{-1}$$, where $$\text{n}$$ = counter size.

Counter clock frequency (Hz) — Clock frequency of external counter

90e6 (default) | scalar

The clock frequency of the external counter.

Block sample time (S) — Sample time after which block executes again

50e-6 (default) | scalar

The time between two consecutive instances of block execution.

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

8 (default) | scalar

Number of pole pairs available in the motor.

Minimum detectable speed (RPM) — Minimum speed that block can detect

20 (default) | scalar

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

Speed measurement interval — Interval over which block measures speed

Every 180 Degrees (default) | Every 60 Degrees

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

Speed unit — Unit of rotor angular speed output

Radians/sec (default) | Degrees/sec | RPM | Per unit

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.

Speed datatype — Data type of rotor angular speed output

single (default) | double | fixdt(1,16,0) | fixdt(1,16,2^0,0) | <data type expression>

Data type of the rotor angular speed output.

Dependencies

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

Position

Expected hall sequence in positive direction — Sequence indicating positive direction

ABC (default) | CBA | Custom sequence

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.

Sequence — Custom sequence indicating positive direction

[5,4,6,2,3,1] (default) | scalar

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.

Order of extrapolation of position — Indicates precision in position computation

1st Order (default) | 2nd Order

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:

${\theta }_{1st Order}={\theta }_{sector}+\omega t$

${\theta }_{2nd Order}={\theta }_{sector}+\omega t+\frac{1}{2}\alpha t^2$

where:

${\theta }_{1st Order}$ = Position computed by using 1st order extrapolation.

${\theta }_{2nd Order}$ = Position computed by using 2nd order extrapolation.

${\theta }_{sector}$ = Sector angle defined by the Hall sensor output.

$\omega$ = Angular velocity of the rotor.

$\alpha$ = 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.

Position unit — Unit of angular speed output

Radians (default) | Degrees | Per unit

Unit of angular speed output.

Dependencies

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

Position datatype — Data type of angular speed output

single (default) | double | fixdt(1,16,0) | fixdt(1,16,2^0,0) | <data type expression>

Data type of angular speed output.

Dependencies

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

Model Examples

Hall Offset Calibration for PMSM Motor

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 (voltage along the stator's d-axis) and a zero (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 by 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).

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™.