Motors are essential part of many electronic equipment’s.
Motors are used in drones, Robots, electric Fan, Elevators and many more products.
In this article I have compiled a list of different types of Motors, their applications and the driver chipsets.
This table can be used as a quick reference guide to select the right motor for your application.
MOTOR APPLICATIONS | Motor Control Technology |
|---|---|
Refrigeration Compressors | AC Induction Motor with Scalar Slip Control, Brushless DC Motor (BLDC) with Commutated Control. |
Washers/ Dryers | AC Induction Motor with Scalar Slip Control, Brushless DC Motor (BLDC) with Commutated Control, Permanent Magnet AC Motor with Field oriented Control, AC Induction motor with Field oriented control. |
Pumps/ Fans/ Blowers | AC Induction Motor with Scalar Slip Control, Brushless DC Motor (BLDC) with Commutated Control, AC Induction motor with Field oriented control. |
Industrial Factory Floor | Permanent Magnet AC Motor with Field oriented Control, AC Induction motor with Field oriented control. |
CNC Tools, Health care scanners | Stepper Motor Control, High Performance DC Servo, Permanent Magnet AC Motor with Field oriented Control. |
Garage Door Openers | AC Induction Motor with Scalar Slip Control. |
Hand Tools | Universal Motor, Brushed DC Motor. |
Kitchen appliances | Universal Motor. |
Computers, Office equipment's | Stepper Motor Control, High Performance DC Servo, Brushless DC Motor (BLDC) with Commutated Control. |
Toys | Brushed DC Motor, Low Performance DC Servo, Stepper Motor, Brushless DC Motor (BLDC) with Commutated Control. |
Types of Motor Controllers
Scalar Control : Scalar Control is the simplest form of controller in which the speed of the induction motor is controlled by varying the magnitude and the frequency of the 3 phase Supply. It just rotates the magnetic field produced by the stator without taking into consideration the position of the rotor.
Vector Control : The vector control technique is used to control the torque and flux of the AC motor. It is also called as Field oriented control. It is an advanced motor control method to generate three-phase sinusoidal signals that can be controlled in frequency and amplitude in order to minimize the current, which means maximizing the power efficiency. The basic idea is to transform three-phase signals into two rotor-fixed signals,
execute control algorithms and transform back to a three-phase system. Feedback on rotor position is also needed by a FOC motor control.
With increased CPU performance, sensor less FOC has been made possible for three-phase motor control in power tool applications. Sensor less FOC doesn’t require any rotor position or speed sensors (e.g. Hall sensors, encoders or resolvers); instead, a software sensor less estimator is used to calculate the rotor position and rotor speed.
Block Commutation Control : Block commutation of three-phase BLDC motors is an electronic commutation scheme also known as trapezoidal commutation, six-step commutation or 120-degree commutation. In this control method, each phase conducts for 120 degrees (electrical degrees) during the positive and negative half of a Back-EMF (BEMF) cycle, and is off or un-energized for the remainder of the cycle. This algorithm requires rotor position information for every 60 degrees, and normally three Hall sensors are used to provide the rotor position feedback.
Trapezoidal control only applies in two windings of the motor leaving the third one unconnected. When the motor turns, the used windings are switched progressively generating a total of six different magnetic field vectors. This control works well in many applications but it introduces a torque ripple due to the misaligned from the optimal direction, which also represents a loss in efficiency.
Hardware Modules in a Motor Controller
The hardware modules used in a Motor control circuit are :
Three phase Inverter : The three-phase inverter’s switching devices are normally N-channel power MOSFETs for battery-powered power tool applications. During the switching, dead-time is inserted into the Pulse Width Modulation (PWM) signals to prevent the high-side and low-side MOSFETs of each inverter leg being on at the same time (i.e. shoot-through). The body diode of each MOSFET helps conduct current whenever necessary when the MOSFET is off. Two or more MOSFETs in parallel for each of the MOSFETs are commonly used to achieve higher output power. Heatsinks may be needed to extract heat efficiently from the power MOSFETs depending on the power tool’s power rating, electronic board design, mechanical design or thermal design.
Gate Drivers : Gate drivers serve as the interface between control signals of the MCU and MOSFETs. Gate drivers output the right voltage and current level to drive the gates of the MOSFETs effectively and efficiently in this PWM switching application. The input signals of gate drivers are from the PWM unit of the MCU. The MCU also executes the algorithms of block commutation with Hall sensors or sensor less FOC to control the three-phase BLDC motor.
Current sensing and amplifiers : Block Commutation requires one leg shunt and one amplifier, Sensor less FOC requires three leg shunts and three amplifiers.
Rotor position sensor : Block commutation requires three hall sensors, Sensor less FOC controller uses a software based estimation and does not require rotor position sensors.
