INTRODUCTION

Brushless DC electric motor (BLDC motors, BL motors) also known as electronically commutated motors (ECMs, EC motors) are synchronous motors which are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor (AC with a caveat – alternating current often implies a sinusoidal waveform; a better term would be bi-directional current with no restriction on waveform); additional sensors and electronics control the inverter output amplitude and waveform( and therefor percent of DC bus usage/efficiency) and frequency ( ie. rotor speed ). The motor part of a brushless motor is often a permanent magnet synchronous motor, but can also be a switched reluctance motor, or induction motor. Brushless motors may be described as stepper motors; however, the term stepper motor tends to be used for motors that are designed specifically to be operated in a mode where they are frequently stopped with the rotor in a defined angular position. This page describes more general brushless motor principles, though there is overlap. Two key performance parameters of brushless DC motors are the Motor constants Kv and Km ( which are numerically equal in SI units).

Conventional dc motors are highly efficient and their characteristics make them suitable for use as servomotors. However, their only drawback is that they need a commutator and brushes which are subject to wear and require maintenance. When the functions of commutator and brushes were implemented by solid-state switches, maintenance-free motors were realised. These motors are now known as brushless dc motors.

THE PERMANENT BRUSHLESS DC MOTOR’S ADVANTAGES,DISADVANTAGES AND APPLICATIONS

Typical brushless DC motors use a rotating permanent magnet in the rotor, and stationary electrical current/coil magnets on the motor housing for the rotor, but the symmetrical opposite is also possible. A motor controller converts DC to AC. This design is simpler than that of brushed motors because it eliminates the complication of transferring power from outside the motor to the spinning rotor. Advantages of brushless motors include long life span, little or no maintenance, and high efficiency.

Brushless motors offer several advantages over brushed DC motors, including more torque per weight, more torque per watt (increased efficiency), increased reliability, reduced noise, longer lifetime (no brush and commutator erosion), elimination of ionizing sparks from the commutator, and overall reduction of electromagnetic interference (EMI). With no windings on the rotor, they are not subjected to centrifugal forces, and because the windings are supported by the housing, they can be cooled by conduction, requiring no airflow inside the motor for cooling. This in turn means that the motor's internals can be entirely enclosed and protected from dirt or other foreign matter.

Application Brushless motor commutation can be implemented in software using a microcontroller or computer, or may alternatively be implemented in analogue hardware or digital firmware using an FPGA. Use of an FPGA provides greater flexibility and capabilities not available with brushed DC motors including speed limiting, "micro stepped" operation for slow and/or fine motion control and a holding torque when stationary. Brushless motors are a popular motor choice for model aircraft including helicopters. Their favorable power-to-weight ratios and large range of available sizes, from under 5 gram to large motors rated at thousands of watts, have revolutionized the market for electric-powered model flight, displacing virtually all brushed electric motors. They have also encouraged a growth of simple, lightweight electric model aircraft, rather than the previous internal combustion engines powering larger and heavier models. The large power-to-weight ratio of modern batteries and brush less motors allows models to ascend vertically, rather than climb gradually. The low noise and lack of mess compared to small glow fuel internal combustion engines that are used is another reason for their popularity.

The application of brushless DC motors within industrial engineering primarily focuses on manufacturing engineering or industrial automation design. In manufacturing, brushless motors are primarily used for motion control, positioning or actuation systems.

Brushless motors are ideally suited for manufacturing applications because of their high power

density, good speed-torque characteristics, high efficiency and wide speed ranges and low maintenance. The most common uses of brushless DC motors in industrial engineering are linear motors. servomotors, actuators for industrial robots, extruder drive motors and feed drives for CNC machine tools.

There are some disadvantages for this motors.they are so noisy. The control consists of logic circuitry and a power stage to drive the motor. The control’s logic circuitry is designedto switch current atthe optimum timing point . It receives information about the shaft location and outputs a signal to turn on a specific power device to apply power from the power supply to specific windings of the brushless motor. Some such brushless motors are sometimes referred to as "synchronous motors" although they have no external power supply to be synchronized with, as would be the case with normal AC synchronous motors.The maximum power that can be applied to a brushless motor is limited almost exclusively by heat; too much of which weakens the magnets, and may damage the winding's insulation.

A brushless motor's main disadvantage is higher cost, which arises from two issues. First, brushless motors require complex electronic speed controllers (ESCs) to run. Brushed DC motors can be regulated by a comparatively simple controller, such as a rheostat (variable resistor). However, this reduces efficiency because power is wasted in the rheostat. Second, some practical uses have not been well developed in the commercial sector. For example, in the

radio control (RC) hobby arena, brushless motors are often hand-wound while brushed motors are usually machine-wound.Most of the problems associated with the brush-commutated DC motor have been with the development of the brushless DC motors.The brushless dc motor is basically a permanent magnet DC motor,wherein the commutator and brushless of teh conventional DC motor have been replaced by electronic switches to perform the commutation.with suh an electonically commutated motor (ECM),the electronic circuitry switchers the motor windings at the appropriate time to control the rotation of the machine.In the permanent magnet DC brushless motor ,apermanent magnet rotor is haused within a stator core having an elevtronically commutated winding distributed among the stator teeh.Although various sensors and feedback electronics must be used in the ECM,most of the problems associated with the mechanical brush/commutator arrangement are avoided

CONSTRUCTIONS

Permanent magnet DC motors are much more efficient, lighter and compact than

comparably sized wound DC motors because the permanent magnets replace the

field windings of wound DC motors.  PM DC motors are constructed in two

broad categories: brushed/commutator and brushless. The PM DC commutator

motor uses a rotating armature winding with a stationary field of permanent

magnets; a PM DC brushless motor has a reverse construction: a rotating field of

permanent magnets and a stationary armature winding that is externally

commutated by an electronic control.  (Sales of permanent magnet DC

commutator motors are steadily decreasing while sales of PM DC brushless

motors are increasing due to the absence of brushes and the associated

maintenance of the brushes and commutator.  Subsequent discussion in this

article will refer to the PM DC brushless motor.)

The field PM magnets have two configurations: surface-mounted or interior-

mounted.  Surface-mounted magnets are less expensive but are not suited to

high speeds. Interior-mounted, also called flux concentrating machines,

overcome the shortcoming of surfaced mounted machines in terms of air gap

flux density, harmonics shielding and, in some cases, structural integrity.

In the 19th century, magnets were made of iron but it was known that alloys of

copper, silver and gold made superior magnets.  In 1932, Alnico (alloy of AL,

CU, Fe NI and Co) was developed and reawakened interest in permanent

magnet field excitation. In the past 20 years, other magnetic materials have been

developed: rare earth magnets, which are samarium-cobalt alloys and are the

highest performing magnetic materials.  Rare earth magnets are expensive but

their price is decreasing. Another material is neodymium-iron-boron alloy,

which performs 30 % better than samarium cobalt alloys. The only drawback of

neodymium is its poor corrosion resistance; however, protective coatings have

been developed to overcome this deficiency. 

Ceramic (barium ferrite and strontium ferrite) magnet motors are widely used in

the world today.  They have much higher coercive forces than alnico and are

better able to resist demagnetization.

BRUSHLESS DC MOTORS USED IN INDUSTRIAL APPLICATIONS

FEATURES

Feature Highlights

Our Permanent Magnet DC Motors offer reliable and consistent performance

while offering a high level feature set. Listed below are just some of our PMDC

Motor features:

Long Life Sealed Ball Bearings with High Temperature Grease

Low Loss Steel Laminations

NEMA Rated Magnet Wire

High Efficiency Electrical Designs

High Startup Torque

Precision Dynamic Balancing

External Brush Access

Power Off Dynamic Braking

Excellent Heat Dissipation

High Temp Polyester Varnish Impregnated Armatures

Easily Reversible

UL and CSA Listed

 Brushless DC (BLDC) motors, (also known as DC commutatorless motors,

electronically commutated motors, AC synchronous motors or DC servomotors)

are increasingly replacing brushed DC motors due to their “superior efficiency,

long life, smooth torque delivery, and high speed operation.” Yet, in the past,

their application has been limited due to the additional cost of the complex

motor controller necessary to operate these motors. However, controller costs

have been trending downward in recent years such that application of brushless

dc motors is on the rise and expected to grow.  While they have been

successfully applied in the automotive, HVAC, electronic, computer,

semiconductor and medical industries, BLDC motors have long been used in

industrial applications such as actuators, feed drives for CNC machines,

industrial robots, extruder drives, among others.

Despite the need of a complex motor controller, the simplicity of construction of

BLDC motors offers several inherent advantages not provided with brushed DC

motors in terms of low enertia, high torque and a very wide speed range.

Constructed in an inside-out configuration with a rotor consisting an array of

permanent magnets and a stationary armature that’s excited by an electronic

commutation controller, BLDC motors exhibit better heat dissipation, improved

efficiency and greater power density than brushed DC motors. Their compact

size, reduced weight and high speed range is thanks to the lack of brushes and a

mechanical commutator. To provide the position feedback required in industrial

servo applications, BLDC motors have an encoder (optical or Hall Effect) that

measures the rotor’s position. The feedback signal, generated by the encoder, is

used by the motor controller to produce input signals to excite and electronically

commutate the armature current such that the armature’s magnetic field rotates

with the rotor following along in synchronism. Additional advantages of BLDC

motors include:

Longer service life due to a lack of electrical and friction losses.

Virtually maintenance-free due to a lack of brushes and mechanical

commutators.

Reduced EMI and noise because of the elimination of ionizing spikes from

brushes.

More suitable for hazardous environments (dirt, oil, grease and other foreign

matter) since they can be completely sealed.

Operational characteristics that include (1) high speed, short index moves,

(2) heavy loads, high torque control, (3) short duty cycle moves and (4) high

accel/decel capability. 

Application Highlights

Fork Lifts

Scissor Lifts

Electric Vehicles (AGV’s, Tugs, Go Carts)

Floor Care

Amusement Rides

Robots (Law Enforcement, Military)

Pump Drives

Blower Drives

Reels / Winches

Railroad (Track Switchers, Crossing Gates)

Motorized Commercial Power Switching

Mobile HVAC

Marine Pumps

INDUSTRIAL APPLICATION

For industrial applications, brushless dc motors are primarily used in servo,

actuation, positioning, and variable speed applications where precise motion

control and stable operation are critical for the satisfactory operation of the

manufacturing or industrial process. They are commonly used as:

Linear motors

Servomotors

Actuators for industrial robots

Extruder drive motors

Feed drives for CNC machine tools

Linear Motors

Linear motors produce linear motion  without the need of a transmission system,

such as a ball-and-lead screw, rack-and-pinion, cam, gears or belts, that would

be necessary for rotary motors. Transmission systems are known to introduce

less responsiveness and reduced accuracy. Direct-drive linear motors do not

exhibit these shortcomings. In their simplest form, linear motors are essentially

“unrolled rotary motors in which the poles of the stator have been laid in the

direction of travel.” There are many types of linear motors, ranging from stepper

motors, dc brushed & brushless motors and AC synchronous motors. BLDC

linear servomotors consist of a slotted stator with magnetic teeth and a moving

actuator, which has permanent magnets and coil windings. To obtain linear

motion, the motor controller excites the coil windings in the actuator causing an

interaction of the magnetic fields thereby producing linear motion. As direct-

drive linear motors, BLDC motors have the added advantages of maintenance-

free operation with no mechanical connections, hysteresis or pitch cyclical

error. 

Servomotors

Servomotors are used for mechanical displacement, positioning or precision

motion control based upon an input control and output feedback signal that

establishes a tightly controlled, stable, closed loop operation. Servomotor drives

are commonly used in machine tool servos, robotic actuator drives, among

others. What sets servomotor applications apart from other types of motor

control is their inherent high dynamic response, smooth torque production, high

reliability and robust control even when there are wide variations in load inertia

or motor parameters.  In the past DC stepper motors were used as servomotors;

however, since they are operate with open loop control, they typically exhibit

torque pulsations. Brushless DC motor are more suitable as servomotors due to

the feedback capability of the motor.

Actuators for Industrial Robots

Permanent magnet DC motors primarily function as the actuators to move the

joints of industrial robots for pick-and-place or tool positioning in assembly,

welding and painting operations. (It merits noting that when heavy payloads are

involved, hydraulic motors are typically used. BLDC motors are preferred over

brushed motors in robotic applications due to their compact size, power density,

and maintenance-free characteristics. They also perform more reliably in less

favorable or hazardous environments.

Extruder Drive Motors

The function of the extruder drive & motor is to provide energy to turn the

screw that compresses the polymer.  DC drives are the most popular extruder

drive due to their low cost and versatility. Since variations in screw speed can

change the dimensions of the final extruded product, a precision motion control

system is required to ensure product quality. Brushless DC drives have been

frequently used in extruder drives. because they offer full torque over the entire

speed range with short-term speed errors as low as 0%.

Feed Drives for CNC Machine Mools

There are two drives used in CNC machine tools: spindle and feed

drives. Spindle drives provide the motion and power for drilling, milling or

grinding operation while feed drives function as axis drive motors and

essentially replace the “manual hand wheel controls used in conventional

machine tools.”  While spindle drives use large DC shunt or AC squirrel cage

induction motors, feed drives, on the other hand, typically use DC servomotors

with an electronic controller. Brushless DC servomotors are used for their good

heat dissipation, reduced rotor inertia and the advantage of maintenance free

operation

CONSTRUCTIONS

Permanent magnet DC motors are much more efficient, lighter and compact than

comparably sized wound DC motors because the permanent magnets replace the

field windings of wound DC motors.  PM DC motors are constructed in two

broad categories: brushed/commutator and brushless. The PM DC commutator

motor uses a rotating armature winding with a stationary field of permanent

magnets; a PM DC brushless motor has a reverse construction: a rotating field of

permanent magnets and a stationary armature winding that is externally

commutated by an electronic control.  (Sales of permanent magnet DC

commutator motors are steadily decreasing while sales of PM DC brushless

motors are increasing due to the absence of brushes and the associated

maintenance of the brushes and commutator.  Subsequent discussion in this

article will refer to the PM DC brushless motor.)

The field PM magnets have two configurations: surface-mounted or interior-

mounted.  Surface-mounted magnets are less expensive but are not suited to

high speeds. Interior-mounted, also called flux concentrating machines,

overcome the shortcoming of surfaced mounted machines in terms of air gap

flux density, harmonics shielding and, in some cases, structural integrity.

In the 19th century, magnets were made of iron but it was known that alloys of

copper, silver and gold made superior magnets.  In 1932, Alnico (alloy of AL,

CU, Fe NI and Co) was developed and reawakened interest in permanent

magnet field excitation. In the past 20 years, other magnetic materials have been

developed: rare earth magnets, which are samarium-cobalt alloys and are the

highest performing magnetic materials.  Rare earth magnets are expensive but

their price is decreasing. Another material is neodymium-iron-boron alloy,

which performs 30 % better than samarium cobalt alloys. The only drawback of

neodymium is its poor corrosion resistance; however, protective coatings have

been developed to overcome this deficiency. 

Ceramic (barium ferrite and strontium ferrite) magnet motors are widely used in

the world today.  They have much higher coercive forces than alnico and are

better able to resist demagnetization.

BRUSHLESS DC MOTORS USED IN INDUSTRIAL APPLICATIONS

FEATURES

Feature Highlights

Our Permanent Magnet DC Motors offer reliable and consistent performance

while offering a high level feature set. Listed below are just some of our PMDC

Motor features:

Long Life Sealed Ball Bearings with High Temperature Grease

Low Loss Steel Laminations

NEMA Rated Magnet Wire

High Efficiency Electrical Designs

High Startup Torque

Precision Dynamic Balancing

External Brush Access

Power Off Dynamic Braking

Excellent Heat Dissipation

High Temp Polyester Varnish Impregnated Armatures

Easily Reversible

UL and CSA Listed

  Brushless DC (BLDC) motors, (also known as DC commutatorless

motors, electronically commutated motors, AC synchronous motors or DC

servomotors) are increasingly replacing brushed DC motors due to their

“superior efficiency, long life, smooth torque delivery, and high speed

operation.” Yet, in the past, their application has been limited due to the

additional cost of the complex motor controller necessary to operate these

motors. However, controller costs have been trending downward in recent years

such that application of brushless dc motors is on the rise and expected to

grow.  While they have been successfully applied in the automotive, HVAC,

electronic, computer, semiconductor and medical industries, BLDC motors have

long been used in industrial applications such as actuators, feed drives for CNC

machines, industrial robots, extruder drives, among others.

Despite the need of a complex motor controller, the simplicity of construction

of BLDC motors offers several inherent advantages not provided with

brushed DC motors in terms of low enertia, high torque and a very wide speed

range. Constructed in an inside-out configuration with a rotor consisting an array

of permanent magnets and a stationary armature that’s excited by an electronic

commutation controller, BLDC motors exhibit better heat dissipation, improved

efficiency and greater power density than brushed DC motors. Their compact

size, reduced weight and high speed range is thanks to the lack of brushes and a

mechanical commutator. To provide the position feedback required in industrial

servo applications, BLDC motors have an encoder (optical or Hall Effect) that

measures the rotor’s position. The feedback signal, generated by the encoder, is

used by the motor controller to produce input signals to excite and electronically

commutate the armature current such that the armature’s magnetic field rotates

with the rotor following along in synchronism. Additional advantages of BLDC

motors include:

Longer service life due to a lack of electrical and friction losses.

Virtually maintenance-free due to a lack of brushes and mechanical

commutators.

Reduced EMI and noise because of the elimination of ionizing spikes from

brushes.

More suitable for hazardous environments (dirt, oil, grease and other foreign

matter) since they can be completely sealed.

Operational characteristics that include (1) high speed, short index moves,

(2) heavy loads, high torque control, (3) short duty cycle moves and (4) high

accel/decel capability. 

Application Highlights

Fork Lifts

Scissor Lifts

Electric Vehicles (AGV’s, Tugs, Go Carts)

Floor Care

Amusement Rides

Robots (Law Enforcement, Military)

Pump Drives

Blower Drives

Reels / Winches

Railroad (Track Switchers, Crossing Gates)

Motorized Commercial Power Switching

Mobile HVAC

Marine Pumps

INDUSTRIAL APPLICATION

For industrial applications, brushless dc motors are primarily used in servo,

actuation, positioning, and variable speed applications where precise motion

control and stable operation are critical for the satisfactory operation of the

manufacturing or industrial process. They are commonly used as:

Linear motors

Servomotors

Actuators for industrial robots

Extruder drive motors

Feed drives for CNC machine tools

Linear Motors

Linear motors produce linear motion  without the need of a transmission

system, such as a ball-and-lead screw, rack-and-pinion, cam, gears or belts, that

would be necessary for rotary motors. Transmission systems are known to

introduce less responsiveness and reduced accuracy. Direct-drive linear motors

do not exhibit these shortcomings. In their simplest form, linear motors are

essentially “unrolled rotary motors in which the poles of the stator have been

laid in the direction of travel.” There are many types of linear motors, ranging

from stepper motors, dc brushed & brushless motors and AC synchronous

motors. BLDC linear servomotors consist of a slotted stator with magnetic teeth

and a moving actuator, which has permanent magnets and coil windings. To

obtain linear motion, the motor controller excites the coil windings in the

actuator causing an interaction of the magnetic fields thereby producing linear

motion. As direct-drive linear motors, BLDC motors have the added advantages

of maintenance-free operation with no mechanical connections, hysteresis or

pitch cyclical error. 

Servomotors

Servomotors are used for mechanical displacement, positioning or precision

motion control based upon an input control and output feedback signal that

establishes a tightly controlled, stable, closed loop operation. Servomotor drives

are commonly used in machine tool servos, robotic actuator drives, among

others. What sets servomotor applications apart from other types of motor

control is their inherent high dynamic response, smooth torque production, high

reliability and robust control even when there are wide variations in load inertia

or motor parameters.  In the past DC stepper motors were used as servomotors;

however, since they are operate with open loop control, they typically exhibit

torque pulsations. Brushless DC motor are more suitable as servomotors due to

the feedback capability of the motor.

Actuators for Industrial Robots

Permanent magnet DC motors primarily function as the actuators to move

the joints of industrial robots for pick-and-place or tool positioning in assembly,

welding and painting operations. (It merits noting that when heavy payloads are

involved, hydraulic motors are typically used. BLDC motors are preferred over

brushed motors in robotic applications due to their compact size, power density,

and maintenance-free characteristics. They also perform more reliably in less

favorable or hazardous environments.

Extruder Drive Motors

The function of the extruder drive & motor is to provide energy to turn the

screw that compresses the polymer.  DC drives are the most popular extruder

drive due to their low cost and versatility. Since variations in screw speed can

change the dimensions of the final extruded product, a precision motion control

system is required to ensure product quality. Brushless DC drives have been

frequently used in extruder drives. because they offer full torque over the entire

speed range with short-term speed errors as low as 0%.

Feed Drives for CNC Machine Mools

There are two drives used in CNC machine tools: spindle and feed

drives. Spindle drives provide the motion and power for drilling, milling or

grinding operation while feed drives function as axis drive motors and

essentially replace the “manual hand wheel controls used in conventional

machine tools.”  While spindle drives use large DC shunt or AC squirrel cage

induction motors, feed drives, on the other hand, typically use DC servomotors

with an electronic controller. Brushless DC servomotors are used for their good

heat dissipation, reduced rotor inertia and the advantage of maintenance free

operation

CHARACTERISTICS

Permanent magnet DC motors have similar characteristics to DC shunt wound motors in terms of torque, speed, reversing and regenerative braking characteristics.  However, PM DC motors have starting torque several times that of shunt motors and their speed load characteristics are more linear and predictable.  Torque varies a lot with speed, ranging from maximum (stall torque at zero speed) to zero torque at maximum (no load speed). An increase in torque requires a decrease in angular velocity and vice versa.

CONTROLLER IMPLEMENTATIONS

Because the controller must direct the rotor rotation, the controller requires some means of determining the rotor's orientation/position (relative to the stator coils.) Some designs use Hall effect sensors or a rotary encode r  to directly measure the rotor's position. Others measure the back EMF in the undriven coils to infer the rotor position, eliminating the need for separate Hall effect sensors, and therefore are often called sensorless controllers.

A typical controller contains 3 bi-directional outputs (i.e. frequency controlled three phase output), which are controlled by a logic circuit. Simple controllers employ comparators to determine when the output phase should be

advanced, while more advanced controllers employ a microcontroller to manage acceleration, control speed and fine-tune efficiency.

Controllers that sense rotor position based on back-EMF have extra challenges in initiating motion because no back-EMF is produced when the rotor is stationary. This is usually accomplished by beginning rotation from an arbitrary phase, and then skipping to the correct phase if it is found to be wrong. This can cause the motor to run briefly backwards, adding even more complexity to the startup sequence. Other sensorless controllers are capable of measuring winding saturation caused by the position of the magnets to infer the rotor position.

TERMINAL CHARACTERISTICS

In DC MOTORS of 0.1 hp(74.60 watts) or less a permanent magnet is most useful comparing motors below 1.25 inch in diameter,permanent magnet motors runs cooler than wound field types because no power is expanded to maintain a magnetic field.

The permanent magnet field functions perfectly for thousands for hours of operation and losts indefinetly on the shelf.Permanent magnet motorsa re easily reversed by changing the polarity of the voltage applied to the connecting terminals.They are capable of high-stall torque and function perfectly in long duty cycle applications.

Dynamic breaking is easily obtained by marcly applying a short circuit to the motor terminals after voltage is removed.

Figure 1 illustrates a speed-torque current-torque curve for a permanent magnet motor.Each curve is a theoretical straight line since the permanent magnet and armature winding are constant in a given motor.Current varies in proportional to torque and the slope of this curve is a torque constant ‘K’.

Figure 2 shows that with the permanent magnet motor no load speed varies inversely with field strength and stall torque varies directly with field strength.In this illustration curve “a” is the lowest value,curve “b” is the economical and curve “c” is the maximum value of field strength

Figure 3 indicates the result of changing the applied voltage to a permanent magnet motor.No load speed changes proportionally to voltage,resulting in a family of parallel speed-torque curves.Remember that voltage determines speed,and only torque will determine current.

Speed Controller Circuit:

The robot I intend to build will be a 4WD bot with a skid steer system so to do this best I have opted to build 2 a controller system moulded around a 4QD DCI111. (A DCI111 converts radio signals into useable signals) Because of this the inputs on my controllers have to be similar to the 4QD units. The next things to consider are the motors that I will be using. Bosch 750’s seem to be quite popular (so are ford escorts and they are crap) so I will just go ahed and use the many starter motors that I have lying around. This results in

DC Motor Control & Interfacing Circuit:

A permanent magnet DC motor responds to both voltage and current. The steady state voltage across a motor determines the motor’s running speed, and the current through its armature windings determines the torque. Apply a voltage and the motor will start running in one direction; reverse the polarity and the direction will be reversed. If you apply a load to the motor shaft, it will draw more current, if the power supply does not able to provide enough current, the voltage will drop and the speed of the motor will be reduced. However, if the power supply can maintain voltage while supplying the current, the motor will

.

run at the same speed. In general, you can control the speed by applying the appropriate voltage, while torque is controlled by current. In most cases, DC motors are powered up by using fixed DC power supply, therefore; it is more efficient to use a chopping circuit.

Back EMF PM Motor Speed Control Circuit:

A 12 V control supply and a TRW BL11, 30 V motor are used; with minor changes other motor and control voltages can be accommodated. For example, a single 24 V rail could supply both control and motor voltages. Motor and control voltages are kept separate here because CMOS logic is used to start, stop, reverse and oscillate the motor with a variable delay between motor reversals.

Bidirectional DC Motor Speed Controller

This kit allows controlling the speed of a DC motor in both the forward and reverse direction. The range of control is from fully OFF to fully ON in both

directions.This kit overcomes both these problems. The direction and speed is controlled using a single potentiometer. Turning the pot in one direction causes the motor to start spinning.turning the pot in the other direction causes the motor tospin in the opposite direction. The center position on thepot is OFF, forcing the motor to slow and stop before changing direction.

PWM DC Motor Speed Control:

The left half of the 556 dual timer IC is used as a fixed frequency square wave oscillator. The oscillator signal is fed into the right half of the 556 which is configured as a variable pulse width one-shot monostable multivibrator (pulse stretcher).

DC Motor Controlled with PWM Resources:

Here is a description of the driver circuit. It's based on the Microchip AN531 Application Note titled "Remote Positionner". The circuit given in the application Note do not work , so this is a correction of the circuit:

DC MOTOR CONTROL USING A SINGLE SWITCH

This simple circuit lets you run a DC motor in clockwise or anti-clockwise direction and stop it using a single switch. It provides a constant voltage for proper operation of the motor. The glowing of LED1 through LED3 indicates that the motor is in stop, forward rotation and reverse conditions, respectively.

Bidirectional DC motor speed control using Pulse Width Modulation:

The simplest method of implementing microcontroller controlled H-bridge drive of a reversible DC motor is to buy one of many commercial H-bridge IC's availible on the market. These can be purchased separately as an H-Bridge with a separate H-Bridge controller IC, or as an all-in-one IC. Unfortunately, there are several hurdles that sometimes frustrate this approach. Students often find these devices hard to find, as they are apparently in high demand. Secondly, many of these devices have limited current drive ability, such that larger DC motors end up running sluggish or stalling easily. One option is to build your own H-bridge from discrete parts, as shown below.

Low-Cost DC Motor Speed Control with CMOS ICs:

Two low-cost CMOS ICs manage a 12 VDC, current-limited speed control circuit for DC brush motors. The circuit design uses PWM (pulse width modulation) to chop the effectiveinput voltage to the motor. Use of CMOS

devices gives the benefits of low power, minimal heat and improved longevity. The overall design is simple, inexpensive and reliable, and is useful in applications such as embedded DC motor control where efficiency, economy and performance are essential.

Digital Speed Control by Anthony Psaila:

My design is based around three parts:

The controller board. This is a fully digital circuit that takes the 1ms to 2ms pulse from the receiver and converts it into a pwm train at 1Khz. It uses six cmos ics (74hc and 40 series) and a 4Mhz crystal clock. The only other components are one resistor and two capacitors to complete the crystal clock and a capacitor across the supply for smoothing. This was built on a printed board measuring 2 x 2.25 inches using standard components (on the boat there was no shortage of space). If surface mounted devices are used, the lot can be crammed into a much smaller space. The circuit can give a resolution of 128 steps (7bits). Some day I will expand it to have reverse function, but this is better done by a switcher circuit supplied from another channel (my reciever can give 7 channels and I am using only two at present).

What is a Brushless Driver/Controller?

A Brushless Driver and/or Controller is a device that is used to run/control a Brushless Motor. They are also known as Speed Controllers and often referred to as Electronic Speed Control or ESC. Their main purpose is to “drive” the motor, in other words make it run. There are many different types that are manufactured for different applications. The main purpose of a Controller/Driver is to drive a motor at a speed where a signal is taken that represents that demanded speed. If the speed of the motor is measured, then it is a Feedback speed controller or also known as a closed loop speed controller. If the speed isn't measured then it is called an open loop speed controller. A feedback speed controller is more complicated than one that is not, but is much better and more efficient. Motors come in a variety of forms, and the speed controllers/drivers motor driver output will be different dependent on these forms.

How does a Brushless Driver and Controller work?

Theory of a DC motor speed controller/driver

The speed of a DC motor is directly proportional to the supply voltage, so when the supply voltage is reduced, so is the speed, and vice versa. An example is, if your supply voltage is 12 volts and you decrease to 6 volts, then the speed will now run 50% slower than at 12 volts. Now, the question is, how can that be achieved when you have a battery or supply fixed at 12 volts? The speed controller works by varying the average voltage sent to the motor. It could do this by adjusting the voltage sent to the motor, but this is inefficient to do. A much more efficient way to do this is, to switch the motors supply on and off very quickly. When the switching is fast enough the motor will only recognize the average effect. It will not notice that it is actually being switched on and off. The average speed of the motor increases, as the amount of time that the voltage is on increases compared with the amount of time that it is off. This on-off switching is performed by what is called a power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). MOSFETs are devices that can turn very large currents on and off under the control of a low signal level voltage. The time it takes a motor to slow down and speed up depends on the inertia of the rotor, how much torque and friction there is.

History of Brushless Drivers and Controllers:

This takes us back to the 19th century. An electrical engineer and inventor by the name of Harry Ward Leonard introduced the Ward Leonard motor control system in 1891 and was the most widely used type of electric speed control. In a Ward Leonard system, a DC (direct current) generator is driven by a prime mover at a constant speed. The armature of a DC motor is connected directly to the armature of the DC generator. The DC motor drives the load equipment at an adjustable speed. By adjusting the output voltage of the generator, the motor speed is also adjusted, using a rheostat to adjust the excitation current in the field winding. The motor field is sometimes reduced to increase the speed above the base speed, but the motor field current is usually not adjusted. An AC (alternating current) motor is usually the prime mover, but a DC engine or motor can be used instead in order to provide the DC field excitation power supply. This system usually included an exciter generator that is driven by the prime mover. From the 1920s-1980s most electrically driven elevators used the Ward Leonard control system. This control system has been used up until the early 21st century. Different variations were implemented into the Ward Leonard system, but were still called by the same name generally. Electrical and mechanical types of adjustable speed drives and other new types developed after

the Ward Leonard system was introduced. Electron tube types of DC motor controls began to develop in the 1920s, but electronic controls didn’t begin to displace the Ward Leonard system until thyristor controlled drives were developed in the late 1960s. Ward Leonard drives were rapidly becoming obsolete by the mid 1970s, but replacements of existing Ward Leonard drives has continued until the beginning of the 21st century.

Basic types of a Brushless Driver and Controller

There are three different ways that Driver/Controllers are operated:

• Manual

• Remote

• Automatic

There are also different types of Driver/controllers:

• Motor starters

• Reduced voltage starters

• Adjustable-speed drivers

• Intelligent controllers

Anaheim Automation also offers an Integrated Motor and Brushless Driver and Controller. This eliminates installation errors and creates a compact, easy-to-use package.

Where is a Brushless Driver and Controller used?

Brushless Drivers and Controllers are used practically everywhere and anywhere you can find a Brushless motor. Some of the industries they appear in, but not limited to, are:

• Instrumentation

• Medical

• Appliances

• Consumer

• Automotive

• Industrial Automation Equipment

• Aerospace

• Military

What Applications are Brushless Driver and Controller used for?

Some applications brushless driver/controllers are used in are, but not limited to:

• Appliances

ο Wheel encoders

ο Ice tray and dust box position sensing

ο Door and lid open/close detection

ο Low water indicator

ο Motor current monitoring and AC input current detection

• Automotive (High temperature and in cabin)

ο Lighting

ο Wiper systems

ο Airbag deployment systems

ο Brake systems

ο Displays and infotainment

ο Seat belt systems

ο Closure systems

• LED lighting and Displays

ο Billboards

ο Backlighting (cameras, mobile phones, laptop pc’s,etc.)

ο Illumination and signals

• Office Automation

ο Printers

ο Fax machines

ο shredder

• Portable

ο Digital Camera

ο Mobile Phone

How to select a Brushless Driver and Controller?

When selecting a driver/Controller for your motor, many things should be considered. What is your application? You will need to get specifics about the motor and the driver/controller and compare them to see if they are compatible. Once you have figured all this out, you can then begin to compare driver/controllers from different manufacturers.

Advantages for Brushless Driver and Controller

There are many advantages with Brushless. Such as the following, but not limited to:

1. Long lifetime

2. Efficient

3. Customizable

4. Different performance options on one driver/controller

Disadvantages for Brushless Driver and Controller

There are far more advantages than disadvantages for a Brushless driver/controller, but there are a few listed below:

1. High cost

2. Complex circuitry

3. An additional unit to a motor (takes up more space)

Troubleshooting Brushless Driver and Controller

When you are having problems with your Brushless Driver/ controller there are multiple things to look for. Different units will have their own way of indicating a problem of fault within the driver/controller. Most driver/controllers will have a fault light to help indicate a problem that has occurred. Some may have an “alarm” or noise of some sort. Some problems that may occur, but are not limited to are:

1. Blown phase

2. Improper parts within unit

3. Blown parts within unit

4. Improper wiring/installation (Check user guides for specific hook-up diagrams)

There is always the possibility that something maybe shorted internally on the board. This is something you might not be able to fix by yourself. Most companies will have a warranty for the product which will allow you to send it back and get it properly fixed and tested.

Physical Properties of a Brushless Driver and Controller

Brushless driver/controllers come in all types of different shapes and sizes. They can be custom made and ordered from different manufacturers. Although there isn’t a certain shape it, most driver/controllers have a rectangular or square shape to them. They can also come in very small packages as well as very big packages.

Brushless Motor Driver/Controllers consist of, but are not limited to:

◊ PCB (Printed Circuit Board)

◊ Transistors

◊ Capacitors

◊ Resistors

◊ IC, Chips, microchips

◊ Diodes

◊ Potentiometers

◊ Terminal Blocks/ screw terminals

◊ Heat Sinks

◊ LEDs

◊ LCDs

Formulas for a Brushless Driver and Controller

◊ AC to DC

AC (1.414) – 2.8 = DC

◊ Output Power =

(Torque)(No Load Speed)

1351.2

◊ Rated Current =

Torque

(Torque Constant)

◊ Back EMF

Ke = V

kRPM

◊ Setting the Current Limit:

The Current of the motor is monitored by the sense resistor. You can monitor this by using an oscilloscope. You will need to calculate the voltage (in milivolts) to set your cursor on your scope.

Required Maintenance for a Brushless Driver/Controller

Occasionally things go wrong with electronics. You should always make sure the environment of your Driver/Controller is within specifications of the unit so that everything will run smoothly and consistently. The temperature, air, dust, and pressure play a big part in electronics. You always want to make sure those allow your unit to run and operate properly at all times. Those factors are almost always unpredictable and change all the time.