Motor Control

+ BLDC Sensorless

Sensor-less Field oriented control (FOC) of BLDC/PMSM

There are different methods of controlling a BLDC motor. Among them, Field Oriented Control (FOC) gives the best performance in terms of torque ripple and efficiency. Implementation of FOC needs precise rotor position information. Sensors can be mounted on the rotor or within the motor to sense rotor position. But using a position sensor is not feasible for applications that demand high reliability or high speed or where size and cost are constraints. The reference design provides a sensor-less algorithm where a back-emf based estimator is used to estimate rotor position based on a mathematical model of the motor.

Device utilization: 61.38%

+ Stepper Motor

Stepper motor micro-stepping

Stepper motors are used for position control and are designed to operate in open loop (without position feedback). Their inherent stepping ability allows for accurate positioning without feedback. A stepper moor can be controlled through a series of alternate pulses on stepper motor coils. But such a method will result in poor efficiency and torque ripple that generates noise. Micro-stepping along with current control is the efficient way to control stepper motor and minimize noise/vibration caused by torque ripple. Increasing the number of micro-steps improves the performance. The reference design can generate up to 2048 micro-steps and uses the principle of vector control.


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The reference design is a combination of BLDC motor sensor-less control and stepper motor control. 

Size of the design:

Device utilization: 61.38%

+ BLDC with Encoder

BLDC with Encoder 

Rotor position sensors are mandatory in applications that demand full torque at the time of starting and at low speeds. Quadrature encoder is the widely used sensor to sense rotor position with high resolution and low cost. The encoder interface algorithm in the IP converts the signals from encoder into angle and speed that can be used for FOC. The angle is incremented at each transition of the encoder signals through an interrupt. An encoder with high resolution generates interrupts at a faster rate. Implementation of encoder interface in FPGA allows parallel computation of FOC and encoder interface and doesn't affect the FOC loop execution.

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Size of the design:

Device utilization: 31.38%

+ BLDC with HALL

BLDC with Hall Sensors

BLDC motors are fitted with HALL sensors that provide rotor information for commutation of phases. The HALL sensors are generally used for block commutation and are not directly suitable for FOC because of their poor resolution (60⁰ electrical). The HALL interface IP generates high resolution angle from low resolution HALL sensors. The angle and speed computed from HALL interface are used by FOC for efficient control of BLDC motor without torque ripple. As HALL sensors provide absolute position information, the motor can be operated at full torque at the time of starting and at low speeds.

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Size of the design:

Device utilization : 32.21%

+ Induction Motor

Induction motor 

AC Induction motors are used in many industrial and consumer applications. The three-phase induction motors are increasingly used  in industrial aplications like  variable-frequency drives.
Microsemi's induction motor design supports both varaiable-frequency and current control mode. The reference design is very compact with implementation possible using only a 5K LE FPGA. The control loop time computation takes only 1 µs and it also offers features such as over current detection, PWM pulse blocking with in one clock cycle (10 ns) for IGBT fault protection and a wide frequency range (1KHz to 500KHz).

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+ BLDC with Resolver

BLDC with Resolver

For motor control applications where reliability is a crucial factor and need to use a sensor to generate high torque at low speeds and stand still, the conventional optical (encoder) and magnetic (HALL) sensors are not suitable. These sensors are susceptible to temperature, external magnetic field, dirt and other environmental conditions. Resolver sensor is immune to such conditions and operate in harsh environments. A resolver is an inductive sensor that contains a rotor and one primary and two secondary windings that are stationary. The primary winding is excited with a high frequency voltage. A voltage is induced in the secondary windings that is a sine and cosine function of rotor angular position. The device that excites the primary winding and demodulates the measured secondary voltages into angular position is called Resolver to Digital Converter (RDC). The reference design integrates the functionality of an RDC along with Field oriented Control (FOC) to provide an complete resolver based motor control solution. Note: The SmartFusion2 Dual-axis Motor Control Starter Kit doesn’t support direct interface of resolver. It needs an external hardware to interface resolver using J25 connector on the starter kit

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Size of the design: