BLDC Current Controller

Discrete-time Brushless DC Motor current PI controller

• 

Libraries:
Simscape / Electrical / Control / BLDC Control

Description

The BLDC Current Controller block uses this algorithm to control current in a DC brushless motor.

Equations

The BLDC Current Controller produces the duty cycle for a BLDC block by implementing proportional-integral (PI) current control using this equation.

$\text{D}=\left(K_p+K_i\frac{T_{s}z}{z-1}\right)\left(I_{s\_ref}-I_s\right)$

Where:

• D is the duty cycle.

• K_p is the proportional gain.

• K_i is the integral gain.

• T_s is the time period.

• I_{s_ref} is the reference current.

• I_s is the measured current.

• G_zc is the zero cancellation polynomial.

The closed-loop transfer function for the PI control algorithm yields a zero that can be cancelled by using zero-cancellation in the feedforward path. The zero-cancellation transfer function in discrete-time is:

$G_{ZC}\left(z\right)=\frac{\frac{T_s{K}_i}{K_p}}{z+\left(\frac{T_s-\frac{K_p}{K_i}}{\frac{K_p}{K_i}}\right)}.$

The block obtains control signals for the three phases by multiplying the duty cycle by the commutation signals. The resulting three control signals are normalized over the interval [-1, 1].

Examples

BLDC Position Control

Control the rotor angle in a BLDC based electrical drive. An ideal torque source provides the load. The Control subsystem uses a PI-based cascade control structure with three control loops, an outer position control loop, a speed control loop and an inner current control loop. The BLDC is fed by a controlled three-phase inverter. The gate signals for the inverter are obtained from hall signals. The simulation uses step references. The Scopes subsystem contains scopes that allow you to see the simulation results.

• Open Model

Ports

Input

IsRef — Reference current

scalar

Reference current for control.

Data Types: single | double

Is — Measured current

scalar

Actual current.

Data Types: single | double

Reset — External reset

scalar

External reset signal (rising edge) for the integrator.

Data Types: single | double

Hall — Hall sensor

vector

Hall sensor data.

Data Types: single | double

Direction — Motor direction

scalar

Direction of motor rotation.

Data Types: single | double

Output

vabcRef — Reference voltage

vector

Reference voltage for the a-, b-, and c-phases.

Data Types: single | double

Parameters

Proportional gain — Controller proportional gain, K_p

1 (default) | positive scalar

Proportional gain, K_p, of the controller.

Integral gain — Integral gain, K_i

5 (default) | positive scalar

Integral gain, K_i, of the controller.

Anti-windup gain — Anti-windup gain, K_aw

1 (default) | positive scalar

Anti-windup gain, K_aw, of the controller.

Sample time (-1 for inherited) — Block sample time

-1 (default) | positive scalar

Time, in s, between consecutive block executions. During execution, the block produces outputs and, if appropriate, updates its internal state. For more information, see What Is Sample Time? and Specify Sample Time.

If this block is inside a triggered subsystem, inherit the sample time by setting this parameter to -1. If this block is in a continuous variable-step model, specify the sample time explicitly using a positive scalar.

Dependencies

If you set Sample time (-1 for inherited) to -1 and select the Enable zero cancellation option, the Discretization sample time parameter becomes visible.

Discretization sample time — Sample time for discretization

0.001 (default) | positive scalar

Time, in s, between consecutive discretizations. Discretization is required for zero cancellation.

Dependencies

This parameter is only visible when both these conditions are met:

• Sample time is set to -1.

• Enable zero cancellation is selected.

Enable zero cancellation — Feedforward zero cancellation

off (default) | on

Option to use zero cancellation on the feedforward path.

Dependencies

If you select the Enable zero cancellation option and set Sample time (-1 for inherited) to -1, the Discretization sample time parameter becomes visible.

References

[1] Stirban, A., I. Boldea, and G. D. Andreescu. "Motion-Sensorless Control of BLDC-PM Motor With Offline FEM-Information-Assisted Position and Speed Observer." IEEE Transactions on Industry Applications. 48, no. 6 (2012): 1950-1958.

Extended Capabilities

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

Version History

Introduced in R2018a