Permanent magnet dc motors
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Permanent magnet dc motors Document Transcript

  • 1. INTRODUCTIONBrushless DC electric motor (BLDC motors, BL motors) also known aselectronically commutated motors (ECMs, EC motors) are synchronous motorswhich are powered by a DC electric source via an integrated inverter/switchingpower supply, which produces an AC electric signal to drive the motor (AC witha caveat – alternating current often implies a sinusoidal waveform; a better termwould be bi-directional current with no restriction on waveform); additionalsensors and electronics control the inverter output amplitude and waveform( andtherefor percent of DC bus usage/efficiency) and frequency ( ie. rotor speed ).The motor part of a brushless motor is often a permanent magnet synchronousmotor, but can also be a switched reluctance motor, or induction motor.Brushless motors may be described as stepper motors; however, the term steppermotor tends to be used for motors that are designed specifically to be operated ina mode where they are frequently stopped with the rotor in a defined angularposition. This page describes more general brushless motor principles, thoughthere is overlap. Two key performance parameters of brushless DC motors arethe Motor constants Kv and Km ( which are numerically equal in SI units).Conventional dc motors are highly efficient and their characteristics make themsuitable for use as servomotors. However, their only drawback is that they needa commutator and brushes which are subject to wear and require maintenance.When the functions of commutator and brushes were implemented by solid-stateswitches, maintenance-free motors were realised. These motors are now knownas brushless dc motors.
  • 2. THE PERMANENT BRUSHLESS DC MOTOR’S ADVANTAGES,DISADVANTAGES AND APPLICATIONSTypical brushless DC motors use a rotating permanent magnet in the rotor, andstationary electrical current/coil magnets on the motor housing for the rotor, butthe symmetrical opposite is also possible. A motor controller converts DC toAC. This design is simpler than that of brushed motors because it eliminates thecomplication 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.
  • 3. Brushless motors offer several advantages over brushed DC motors, includingmore torque per weight, more torque per watt (increased efficiency), increasedreliability, reduced noise, longer lifetime (no brush and commutator erosion),elimination of ionizing sparks from the commutator, and overall reduction ofelectromagnetic interference (EMI). With no windings on the rotor, they are notsubjected to centrifugal forces, and because the windings are supported by thehousing, they can be cooled by conduction, requiring no airflow inside the motorfor cooling. This in turn means that the motors internals can be entirely enclosedand protected from dirt or other foreign matter.Application Brushless motor commutation can be implemented in softwareusing a microcontroller or computer, or may alternatively be implemented inanalogue hardware or digital firmware using an FPGA. Use of an FPGAprovides greater flexibility and capabilities not available with brushed DCmotors including speed limiting, "micro stepped" operation for slow and/or finemotion control and a holding torque when stationary. Brushless motors are apopular motor choice for model aircraft including helicopters. Their favorablepower-to-weight ratios and large range of available sizes, from under 5 gram tolarge motors rated at thousands of watts, have revolutionized the market forelectric-powered model flight, displacing virtually all brushed electric motors.They have also encouraged a growth of simple, lightweight electric modelaircraft, rather than the previous internal combustion engines powering largerand heavier models. The large power-to-weight ratio of modern batteries andbrush less motors allows models to ascend vertically, rather than climbgradually. The low noise and lack of mess compared to small glow fuel internalcombustion engines that are used is another reason for their popularity.
  • 4. The application of brushless DC motors within industrial engineering primarilyfocuses on manufacturing engineering or industrial automation design. Inmanufacturing, brushless motors are primarily used for motion control,positioning or actuation systems.Brushless motors are ideally suited for manufacturing applications because oftheir high powerdensity, good speed-torque characteristics, high efficiency and wide speedranges and low maintenance. The most common uses of brushless DC motors inindustrial engineering are linear motors. servomotors, actuators for industrialrobots, extruder drive motors and feed drives for CNC machine tools. There are some disadvantages for this motors.they are so noisy. The controlconsists of logic circuitry and a power stage to drive the motor. The control‟slogic circuitry is designedto switch current atthe optimum timing point . Itreceives information about the shaft location and outputs a signal to turn on aspecific power device to apply power from the power supply to specificwindings of the brushless motor. Some such brushless motors are sometimesreferred to as "synchronous motors" although they have no external powersupply to be synchronized with, as would be the case with normal ACsynchronous motors.The maximum power that can be applied to a brushlessmotor is limited almost exclusively by heat; too much of which weakens themagnets, and may damage the windings insulation. A brushless motors main disadvantage is higher cost, which arises from twoissues. First, brushless motors require complex electronic speed controllers(ESCs) to run. Brushed DC motors can be regulated by a comparatively simplecontroller, such as a rheostat (variable resistor). However, this reducesefficiency because power is wasted in the rheostat. Second, some practical useshave not been well developed in the commercial sector. For example, in the
  • 5. radio control (RC) hobby arena, brushless motors are often hand-wound whilebrushed motors are usually machine-wound.Most of the problems associatedwith the brush-commutated DC motor have been with the development of thebrushless DC motors.The brushless dc motor is basically a permanent magnetDC motor,wherein the commutator and brushless of teh conventional DC motorhave been replaced by electronic switches to perform the commutation.with suhan electonically commutated motor (ECM),the electronic circuitry switchers themotor windings at the appropriate time to control the rotation of the machine.Inthe permanent magnet DC brushless motor ,apermanent magnet rotor is hausedwithin a stator core having an elevtronically commutated winding distributedamong the stator teeh.Although various sensors and feedback electronics mustbe used in the ECM,most of the problems associated with the mechanicalbrush/commutator arrangement are avoided CONSTRUCTIONSPermanent magnet DC motors are much more efficient, lighter and compact thancomparably sized wound DC motors because the permanent magnets replace thefield windings of wound DC motors. PM DC motors are constructed in twobroad categories: brushed/commutator and brushless. The PM DC commutatormotor uses a rotating armature winding with a stationary field of permanentmagnets; a PM DC brushless motor has a reverse construction: a rotating field ofpermanent magnets and a stationary armature winding that is externallycommutated by an electronic control. (Sales of permanent magnet DCcommutator motors are steadily decreasing while sales of PM DC brushlessmotors are increasing due to the absence of brushes and the associatedmaintenance of the brushes and commutator. Subsequent discussion in thisarticle 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 tohigh speeds. Interior-mounted, also called flux concentrating machines,overcome the shortcoming of surfaced mounted machines in terms of air gapflux density, harmonics shielding and, in some cases, structural integrity.
  • 6. In the 19th century, magnets were made of iron but it was known that alloys ofcopper, silver and gold made superior magnets. In 1932, Alnico (alloy of AL,CU, Fe NI and Co) was developed and reawakened interest in permanentmagnet field excitation. In the past 20 years, other magnetic materials have beendeveloped: rare earth magnets, which are samarium-cobalt alloys and are thehighest performing magnetic materials. Rare earth magnets are expensive buttheir price is decreasing. Another material is neodymium-iron-boron alloy,which performs 30 % better than samarium cobalt alloys. The only drawback ofneodymium is its poor corrosion resistance; however, protective coatings havebeen developed to overcome this deficiency.Ceramic (barium ferrite and strontium ferrite) magnet motors are widely used inthe world today. They have much higher coercive forces than alnico and arebetter able to resist demagnetization.BRUSHLESS DC MOTORS USED IN INDUSTRIAL APPLICATIONSFEATURESFeature HighlightsOur Permanent Magnet DC Motors offer reliable and consistent performancewhile offering a high level feature set. Listed below are just some of our PMDCMotor features: Long Life Sealed Ball Bearings with High Temperature Grease Low Loss Steel Laminations NEMA Rated Magnet Wire High Efficiency Electrical Designs
  • 7.  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 complexmotor controller necessary to operate these motors. However, controller costshave been trending downward in recent years such that application of brushlessdc motors is on the rise and expected to grow. While they have beensuccessfully applied in the automotive, HVAC, electronic, computer,semiconductor and medical industries, BLDC motors have long been used inindustrial 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 ofBLDC motors offers several inherent advantages not provided with brushed DCmotors 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 ofpermanent magnets and a stationary armature that‟s excited by an electroniccommutation controller, BLDC motors exhibit better heat dissipation, improved
  • 8. efficiency and greater power density than brushed DC motors. Their compactsize, reduced weight and high speed range is thanks to the lack of brushes and amechanical commutator. To provide the position feedback required in industrialservo applications, BLDC motors have an encoder (optical or Hall Effect) thatmeasures the rotor‟s position. The feedback signal, generated by the encoder, isused by the motor controller to produce input signals to excite and electronicallycommutate the armature current such that the armature‟s magnetic field rotateswith the rotor following along in synchronism. Additional advantages of BLDCmotors 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)
  • 9.  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 PumpsINDUSTRIAL APPLICATIONFor industrial applications, brushless dc motors are primarily used in servo,actuation, positioning, and variable speed applications where precise motioncontrol and stable operation are critical for the satisfactory operation of themanufacturing or industrial process. They are commonly used as: Linear motors Servomotors Actuators for industrial robots Extruder drive motors Feed drives for CNC machine tools
  • 10. Linear MotorsLinear 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 wouldbe necessary for rotary motors. Transmission systems are known to introduceless responsiveness and reduced accuracy. Direct-drive linear motors do notexhibit these shortcomings. In their simplest form, linear motors are essentially“unrolled rotary motors in which the poles of the stator have been laid in thedirection of travel.” There are many types of linear motors, ranging from steppermotors, dc brushed & brushless motors and AC synchronous motors. BLDClinear servomotors consist of a slotted stator with magnetic teeth and a movingactuator, which has permanent magnets and coil windings. To obtain linearmotion, the motor controller excites the coil windings in the actuator causing aninteraction 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 cyclicalerror.ServomotorsServomotors are used for mechanical displacement, positioning or precisionmotion control based upon an input control and output feedback signal thatestablishes a tightly controlled, stable, closed loop operation. Servomotor drivesare commonly used in machine tool servos, robotic actuator drives, amongothers. What sets servomotor applications apart from other types of motorcontrol is their inherent high dynamic response, smooth torque production, highreliability and robust control even when there are wide variations in load inertia
  • 11. or motor parameters. In the past DC stepper motors were used as servomotors;however, since they are operate with open loop control, they typically exhibittorque pulsations. Brushless DC motor are more suitable as servomotors due tothe feedback capability of the motor.Actuators for Industrial RobotsPermanent magnet DC motors primarily function as the actuators to move thejoints of industrial robots for pick-and-place or tool positioning in assembly,welding and painting operations. (It merits noting that when heavy payloads areinvolved, hydraulic motors are typically used. BLDC motors are preferred overbrushed motors in robotic applications due to their compact size, power density,and maintenance-free characteristics. They also perform more reliably in lessfavorable or hazardous environments.Extruder Drive MotorsThe function of the extruder drive & motor is to provide energy to turn thescrew that compresses the polymer. DC drives are the most popular extruderdrive due to their low cost and versatility. Since variations in screw speed canchange the dimensions of the final extruded product, a precision motion controlsystem is required to ensure product quality. Brushless DC drives have beenfrequently used in extruder drives. because they offer full torque over the entirespeed range with short-term speed errors as low as 0%.Feed Drives for CNC Machine MoolsThere are two drives used in CNC machine tools: spindle and feeddrives. Spindle drives provide the motion and power for drilling, milling orgrinding operation while feed drives function as axis drive motors and
  • 12. essentially replace the “manual hand wheel controls used in conventionalmachine tools.” While spindle drives use large DC shunt or AC squirrel cageinduction motors, feed drives, on the other hand, typically use DC servomotorswith an electronic controller. Brushless DC servomotors are used for their goodheat dissipation, reduced rotor inertia and the advantage of maintenance freeoperation CONSTRUCTIONSPermanent magnet DC motors are much more efficient, lighter and compact thancomparably sized wound DC motors because the permanent magnets replace thefield windings of wound DC motors. PM DC motors are constructed in twobroad categories: brushed/commutator and brushless. The PM DC commutatormotor uses a rotating armature winding with a stationary field of permanentmagnets; a PM DC brushless motor has a reverse construction: a rotating field ofpermanent magnets and a stationary armature winding that is externallycommutated by an electronic control. (Sales of permanent magnet DCcommutator motors are steadily decreasing while sales of PM DC brushlessmotors are increasing due to the absence of brushes and the associatedmaintenance of the brushes and commutator. Subsequent discussion in thisarticle 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 tohigh speeds. Interior-mounted, also called flux concentrating machines,overcome the shortcoming of surfaced mounted machines in terms of air gapflux density, harmonics shielding and, in some cases, structural integrity.In the 19th century, magnets were made of iron but it was known that alloys ofcopper, silver and gold made superior magnets. In 1932, Alnico (alloy of AL,CU, Fe NI and Co) was developed and reawakened interest in permanentmagnet field excitation. In the past 20 years, other magnetic materials have been
  • 13. developed: rare earth magnets, which are samarium-cobalt alloys and are thehighest performing magnetic materials. Rare earth magnets are expensive buttheir price is decreasing. Another material is neodymium-iron-boron alloy,which performs 30 % better than samarium cobalt alloys. The only drawback ofneodymium is its poor corrosion resistance; however, protective coatings havebeen developed to overcome this deficiency.Ceramic (barium ferrite and strontium ferrite) magnet motors are widely used inthe world today. They have much higher coercive forces than alnico and arebetter able to resist demagnetization. BRUSHLESS DC MOTORS USED IN INDUSTRIAL APPLICATIONSFEATURESFeature HighlightsOur Permanent Magnet DC Motors offer reliable and consistent performancewhile offering a high level feature set. Listed below are just some of our PMDCMotor 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
  • 14.  Excellent Heat Dissipation High Temp Polyester Varnish Impregnated Armatures Easily Reversible UL and CSA Listed Brushless DC (BLDC) motors, (also known as DC commutatorlessmotors, electronically commutated motors, AC synchronous motors or DCservomotors) are increasingly replacing brushed DC motors due to their“superior efficiency, long life, smooth torque delivery, and high speedoperation.” Yet, in the past, their application has been limited due to theadditional cost of the complex motor controller necessary to operate thesemotors. However, controller costs have been trending downward in recent yearssuch that application of brushless dc motors is on the rise and expected togrow. While they have been successfully applied in the automotive, HVAC,electronic, computer, semiconductor and medical industries, BLDC motors havelong been used in industrial applications such as actuators, feed drives for CNCmachines, industrial robots, extruder drives, among others. Despite the need of a complex motor controller, the simplicity of constructionof BLDC motors offers several inherent advantages not provided withbrushed DC motors in terms of low enertia, high torque and a very wide speedrange. Constructed in an inside-out configuration with a rotor consisting an arrayof permanent magnets and a stationary armature that‟s excited by an electroniccommutation controller, BLDC motors exhibit better heat dissipation, improvedefficiency and greater power density than brushed DC motors. Their compactsize, reduced weight and high speed range is thanks to the lack of brushes and amechanical commutator. To provide the position feedback required in industrialservo applications, BLDC motors have an encoder (optical or Hall Effect) that
  • 15. measures the rotor‟s position. The feedback signal, generated by the encoder, isused by the motor controller to produce input signals to excite and electronicallycommutate the armature current such that the armature‟s magnetic field rotateswith the rotor following along in synchronism. Additional advantages of BLDCmotors 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)
  • 16.  Pump Drives  Blower Drives  Reels / Winches Railroad (Track Switchers, Crossing Gates) Motorized Commercial Power Switching Mobile HVAC Marine PumpsINDUSTRIAL APPLICATION For industrial applications, brushless dc motors are primarily used in servo,actuation, positioning, and variable speed applications where precise motioncontrol and stable operation are critical for the satisfactory operation of themanufacturing or industrial process. They are commonly used as: Linear motors Servomotors Actuators for industrial robots Extruder drive motors Feed drives for CNC machine toolsLinear Motors Linear motors produce linear motion without the need of a transmissionsystem, such as a ball-and-lead screw, rack-and-pinion, cam, gears or belts, that
  • 17. would be necessary for rotary motors. Transmission systems are known tointroduce less responsiveness and reduced accuracy. Direct-drive linear motorsdo not exhibit these shortcomings. In their simplest form, linear motors areessentially “unrolled rotary motors in which the poles of the stator have beenlaid in the direction of travel.” There are many types of linear motors, rangingfrom stepper motors, dc brushed & brushless motors and AC synchronousmotors. BLDC linear servomotors consist of a slotted stator with magnetic teethand a moving actuator, which has permanent magnets and coil windings. Toobtain linear motion, the motor controller excites the coil windings in theactuator causing an interaction of the magnetic fields thereby producing linearmotion. As direct-drive linear motors, BLDC motors have the added advantagesof maintenance-free operation with no mechanical connections, hysteresis orpitch cyclical error.ServomotorsServomotors are used for mechanical displacement, positioning or precisionmotion control based upon an input control and output feedback signal thatestablishes a tightly controlled, stable, closed loop operation. Servomotor drivesare commonly used in machine tool servos, robotic actuator drives, amongothers. What sets servomotor applications apart from other types of motorcontrol is their inherent high dynamic response, smooth torque production, highreliability and robust control even when there are wide variations in load inertiaor motor parameters. In the past DC stepper motors were used as servomotors;however, since they are operate with open loop control, they typically exhibittorque pulsations. Brushless DC motor are more suitable as servomotors due tothe feedback capability of the motor.Actuators for Industrial Robots Permanent magnet DC motors primarily function as the actuators to movethe joints of industrial robots for pick-and-place or tool positioning in assembly,
  • 18. welding and painting operations. (It merits noting that when heavy payloads areinvolved, hydraulic motors are typically used. BLDC motors are preferred overbrushed motors in robotic applications due to their compact size, power density,and maintenance-free characteristics. They also perform more reliably in lessfavorable or hazardous environments.Extruder Drive Motors The function of the extruder drive & motor is to provide energy to turn thescrew that compresses the polymer. DC drives are the most popular extruderdrive due to their low cost and versatility. Since variations in screw speed canchange the dimensions of the final extruded product, a precision motion controlsystem is required to ensure product quality. Brushless DC drives have beenfrequently used in extruder drives. because they offer full torque over the entirespeed 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 feeddrives. Spindle drives provide the motion and power for drilling, milling orgrinding operation while feed drives function as axis drive motors andessentially replace the “manual hand wheel controls used in conventionalmachine tools.” While spindle drives use large DC shunt or AC squirrel cageinduction motors, feed drives, on the other hand, typically use DC servomotorswith an electronic controller. Brushless DC servomotors are used for their goodheat dissipation, reduced rotor inertia and the advantage of maintenance freeoperation
  • 19. CHARACTERISTICS Permanent magnet DC motors have similar characteristics to DC shuntwound motors in terms of torque, speed, reversing and regenerative brakingcharacteristics. However, PM DC motors have starting torque several times thatof shunt motors and their speed load characteristics are more linear andpredictable. Torque varies a lot with speed, ranging from maximum (stall torqueat zero speed) to zero torque at maximum (no load speed). An increase in torquerequires a decrease in angular velocity and vice versa. CONTROLLER IMPLEMENTATIONS Because the controller must direct the rotor rotation, the controllerrequires some means of determining the rotors orientation/position (relative tothe stator coils.) Some designs use Hall effect sensors or a rotary encoder todirectly measure the rotors position. Others measure the back EMF in theundriven coils to infer the rotor position, eliminating the need for separate Halleffect sensors, and therefore are often called sensorless controllers.
  • 20. A typical controller contains 3 bi-directional outputs (i.e. frequencycontrolled three phase output), which are controlled by a logic circuit. Simplecontrollers employ comparators to determine when the output phase should beadvanced, while more advanced controllers employ a microcontroller to manageacceleration, control speed and fine-tune efficiency. Controllers that sense rotor position based on back-EMF have extrachallenges in initiating motion because no back-EMF is produced when the rotoris stationary. This is usually accomplished by beginning rotation from anarbitrary 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 morecomplexity to the startup sequence. Other sensorless controllers are capable ofmeasuring winding saturation caused by the position of the magnets to infer therotor position. TERMINAL CHARACTERISTICS In DC MOTORS of 0.1 hp(74.60 watts) or less a permanent magnet ismost useful comparing motors below 1.25 inch in diameter,permanent magnetmotors runs cooler than wound field types because no power is expanded tomaintain a magnetic field. The permanent magnet field functions perfectly for thousands for hours ofoperation and losts indefinetly on the shelf.Permanent magnet motorsa re easilyreversed by changing the polarity of the voltage applied to the connectingterminals.They are capable of high-stall torque and function perfectly in longduty cycle applications. Dynamic breaking is easily obtained by marcly applying a short circuit tothe motor terminals after voltage is removed. Figure 1 illustrates a speed-torque current-torque curve for a permanentmagnet motor.Each curve is a theoretical straight line since the permanentmagnet and armature winding are constant in a given motor.Current varies inproportional to torque and the slope of this curve is a torque constant „K‟.
  • 21. Figure 2 shows that with the permanent magnet motor no load speedvaries inversely with field strength and stall torque varies directly with fieldstrength.In this illustration curve “a” is the lowest value,curve “b” is theeconomical and curve “c” is the maximum value of field strength Figure 3 indicates the result of changing the applied voltage to apermanent magnet motor.No load speed changes proportionally tovoltage,resulting in a family of parallel speed-torque curves.Remember thatvoltage determines speed,and only torque will determine current.
  • 22. 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
  • 23. run at the same speed. In general, you can control the speed by applying theappropriate voltage, while torque is controlled by current. In most cases, DCmotors are powered up by using fixed DC power supply, therefore; it is moreefficient 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 minorchanges other motor and control voltages can be accommodated. For example, asingle 24 V rail could supply both control and motor voltages. Motor and controlvoltages 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 ControllerThis kit allows controlling the speed of a DC motor in both the forward andreverse direction. The range of control is from fully OFF to fully ON in both
  • 24. directions.This kit overcomes both these problems. The direction and speed iscontrolled using a single potentiometer. Turning the pot in one direction causesthe motor to start spinning.turning the pot in the other direction causes the motortospin in the opposite direction. The center position on thepot is OFF, forcingthe 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 waveoscillator. The oscillator signal is fed into the right half of the 556 which isconfigured as a variable pulse width one-shot monostable multivibrator (pulsestretcher).
  • 25. DC Motor Controlled with PWM Resources:Here is a description of the driver circuit. Its based on the Microchip AN531Application Note titled "Remote Positionner". The circuit given in theapplication Note do not work , so this is a correction of the circuit:DC MOTOR CONTROL USING A SINGLE SWITCHThis simple circuit lets you run a DC motor in clockwise or anti-clockwisedirection and stop it using a single switch. It provides a constant voltage forproper operation of the motor. The glowing of LED1 through LED3 indicatesthat the motor is in stop, forward rotation and reverse conditions, respectively.
  • 26. Bidirectional DC motor speed control using Pulse Width Modulation:The simplest method of implementing microcontroller controlled H-bridge driveof a reversible DC motor is to buy one of many commercial H-bridge ICsavailible on the market. These can be purchased separately as an H-Bridge witha separate H-Bridge controller IC, or as an all-in-one IC. Unfortunately, thereare several hurdles that sometimes frustrate this approach. Students often findthese devices hard to find, as they are apparently in high demand. Secondly,many of these devices have limited current drive ability, such that larger DCmotors end up running sluggish or stalling easily. One option is to build yourown 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 controlcircuit for DC brush motors. The circuit design uses PWM (pulse widthmodulation) to chop the effectiveinput voltage to the motor. Use of CMOS
  • 27. devices gives the benefits of low power, minimal heat and improved longevity.The overall design is simple, inexpensive and reliable, and is useful inapplications such as embedded DC motor control where efficiency, economyand 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 2mspulse from the receiver and converts it into a pwm train at 1Khz. It uses sixcmos ics (74hc and 40 series) and a 4Mhz crystal clock. The only othercomponents are one resistor and two capacitors to complete the crystal clock anda capacitor across the supply for smoothing. This was built on a printed boardmeasuring 2 x 2.25 inches using standard components (on the boat there was noshortage of space). If surface mounted devices are used, the lot can be crammedinto 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 aswitcher circuit supplied from another channel (my reciever can give 7 channelsand I am using only two at present).
  • 28. What is a Brushless Driver/Controller?A Brushless Driver and/or Controller is a device that is used to run/control aBrushless Motor. They are also known as Speed Controllers and often referredto as Electronic Speed Control or ESC. Their main purpose is to “drive” themotor, in other words make it run. There are many different types that aremanufactured for different applications. The main purpose of aController/Driver is to drive a motor at a speed where a signal is taken thatrepresents that demanded speed. If the speed of the motor is measured, then it isa Feedback speed controller or also known as a closed loop speed controller. Ifthe speed isnt measured then it is called an open loop speed controller. Afeedback speed controller is more complicated than one that is not, but is muchbetter and more efficient. Motors come in a variety of forms, and the speedcontrollers/drivers motor driver output will be different dependent on theseforms.How does a Brushless Driver and Controller work?Theory of a DC motor speed controller/driver
  • 29. The speed of a DC motor is directly proportional to the supply voltage, so whenthe supply voltage is reduced, so is the speed, and vice versa. An example is, ifyour supply voltage is 12 volts and you decrease to 6 volts, then the speed willnow run 50% slower than at 12 volts. Now, the question is, how can that beachieved when you have a battery or supply fixed at 12 volts? The speedcontroller works by varying the average voltage sent to the motor. It could dothis by adjusting the voltage sent to the motor, but this is inefficient to do. Amuch more efficient way to do this is, to switch the motors supply on and offvery quickly. When the switching is fast enough the motor will only recognizethe 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 voltageis on increases compared with the amount of time that it is off. This on-offswitching is performed by what is called a power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). MOSFETs are devices that can turnvery 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 ofthe 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 bythe name of Harry Ward Leonard introduced the Ward Leonard motor controlsystem in 1891 and was the most widely used type of electric speed control. In aWard Leonard system, a DC (direct current) generator is driven by a primemover at a constant speed. The armature of a DC motor is connected directly tothe armature of the DC generator. The DC motor drives the load equipment at anadjustable speed. By adjusting the output voltage of the generator, the motorspeed is also adjusted, using a rheostat to adjust the excitation current in thefield winding. The motor field is sometimes reduced to increase the speed abovethe 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 motorcan 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 primemover. From the 1920s-1980s most electrically driven elevators used the WardLeonard control system. This control system has been used up until the early21st century. Different variations were implemented into the Ward Leonardsystem, but were still called by the same name generally. Electrical andmechanical types of adjustable speed drives and other new types developed after
  • 30. the Ward Leonard system was introduced. Electron tube types of DC motorcontrols began to develop in the 1920s, but electronic controls didn‟t begin todisplace the Ward Leonard system until thyristor controlled drives weredeveloped in the late 1960s. Ward Leonard drives were rapidly becomingobsolete by the mid 1970s, but replacements of existing Ward Leonard driveshas continued until the beginning of the 21st century.Basic types of a Brushless Driver and ControllerThere are three different ways that Driver/Controllers are operated:• Manual• Remote• AutomaticThere are also different types of Driver/controllers:• Motor starters• Reduced voltage starters• Adjustable-speed drivers• Intelligent controllersAnaheim Automation also offers an Integrated Motor and Brushless Driver andController. This eliminates installation errors and creates a compact, easy-to-usepackage.Where is a Brushless Driver and Controller used?Brushless Drivers and Controllers are used practically everywhere and anywhereyou can find a Brushless motor. Some of the industries they appear in, but notlimited to, are:• Instrumentation• Medical• Appliances• Consumer
  • 31. • Automotive• Industrial Automation Equipment• Aerospace• MilitaryWhat Applications are Brushless Driver and Controller used for?Some applications brushless driver/controllers are used in are, but not limited to:• Appliancesο Wheel encodersο Ice tray and dust box position sensingο Door and lid open/close detectionο Low water indicatorο Motor current monitoring and AC input current detection• Automotive (High temperature and in cabin)ο Lightingο Wiper systemsο Airbag deployment systemsο Brake systemsο Displays and infotainmentο Seat belt systemsο Closure systems• LED lighting and Displaysο Billboardsο Backlighting (cameras, mobile phones, laptop pc‟s,etc.)ο Illumination and signals
  • 32. • Office Automationο Printersο Fax machinesο shredder• Portableο Digital Cameraο Mobile PhoneHow to select a Brushless Driver and Controller?When selecting a driver/Controller for your motor, many things should beconsidered. What is your application? You will need to get specifics about themotor 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 comparedriver/controllers from different manufacturers.Advantages for Brushless Driver and ControllerThere are many advantages with Brushless. Such as the following, but notlimited to:1. Long lifetime2. Efficient3. Customizable4. Different performance options on one driver/controllerDisadvantages for Brushless Driver and ControllerThere are far more advantages than disadvantages for a Brushlessdriver/controller, but there are a few listed below:1. High cost2. Complex circuitry3. An additional unit to a motor (takes up more space)
  • 33. Troubleshooting Brushless Driver and ControllerWhen you are having problems with your Brushless Driver/ controller there aremultiple things to look for. Different units will have their own way of indicatinga problem of fault within the driver/controller. Most driver/controllers will havea 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 notlimited to are:1. Blown phase2. Improper parts within unit3. Blown parts within unit4. Improper wiring/installation (Check user guides for specific hook-updiagrams)There is always the possibility that something maybe shorted internally on theboard. This is something you might not be able to fix by yourself. Mostcompanies will have a warranty for the product which will allow you to send itback and get it properly fixed and tested.Physical Properties of a Brushless Driver and ControllerBrushless driver/controllers come in all types of different shapes and sizes. Theycan be custom made and ordered from different manufacturers. Although thereisn‟t a certain shape it, most driver/controllers have a rectangular or squareshape to them. They can also come in very small packages as well as very bigpackages.Brushless Motor Driver/Controllers consist of, but are not limited to:◊ PCB (Printed Circuit Board)
  • 34. ◊ Transistors◊ Capacitors◊ Resistors◊ IC, Chips, microchips◊ Diodes◊ Potentiometers◊ Terminal Blocks/ screw terminals◊ Heat Sinks◊ LEDs◊ LCDsFormulas for a Brushless Driver and Controller◊ AC to DCAC (1.414) – 2.8 = DC◊ Output Power =(Torque)(No Load Speed)1351.2◊ Rated Current = Torque(Torque Constant)◊ Back EMFKe = VkRPM◊ Setting the Current Limit:
  • 35. The Current of the motor is monitored by the sense resistor. You can monitorthis by using an oscilloscope. You will need to calculate the voltage (inmilivolts) to set your cursor on your scope.Required Maintenance for a Brushless Driver/ControllerOccasionally things go wrong with electronics. You should always make surethe environment of your Driver/Controller is within specifications of the unit sothat everything will run smoothly and consistently. The temperature, air, dust,and pressure play a big part in electronics. You always want to make sure thoseallow your unit to run and operate properly at all times. Those factors are almostalways unpredictable and change all the time.