MOTOR CONTROLLERSamp DRIVESBUYING GUIDE

For more Buying Guides visit WWWTHOMASNETCOMIndustryrsquos go to Platform for Supplier Discovery

MOTOR CONTROLLERS AND DRIVES A ThomasNet Buying Guide

Motor Controllers and Drives are electrical or electronic

devices that regulate motor speed torque and position

outputs The drive modifies the power input to the motor to achieve the desired output The controller

circuits are commonly integrated with the drive circuits as one stand-alone unit thus the terms motor

drive and motor controller are frequently used interchangeably There are four basic motor controller

and drive types AC DC servo and stepper each having an input power type modified to a desired

output function to match with an application

Motor Controller and Drive Types

AC AC Motor Controllers and Drives are electronic devices that modify

the input power to motors by typically adjusting the frequency of the

power to the motor for the purpose of regulating the output speed

and torque Key specifications include the intended application drive

operating mode motor type inverter type loop system voltage

classification power rating communication interface as well as

input and output electrical specifications AC motor controllers and

drives are used primarily in process applications to control the speed

of pumps fans blowers etc They are known as variable speed

drives adjustable frequency drives or AC inverters The controller

commonly integrated with the drive circuits supplies the control

signals to the drive

DC DC Motor Controllers and Drives are electrical devices that modify the

input power by adjusting the constant or alternating current source to a

pulsed direct current output of varying pulse duration or frequency Key

specifications include the intended application drive operating mode

motor type loop system voltage classification power rating output signal

type communication interface as well as input and output electrical

specifications DC motor controllers and drives are used primarily to

control motor speeds and torques for machine tools electric vehicles

pumps etc The controller commonly integrated with the drive circuits supplies the control signals to

the drive

Servomotor Servo Motor Controllers and Drives are electronic devices that modify

the input power by adjusting the constant or alternating current source

to a pulsed current output of varying pulse duration or frequency Key

specifications include the intended application motor type drive

operating mode loop system power rating output signal type

communication interface as well as electrical specifications Servo

motor controllers and drives are used primarily in motion control

applications in manufacturing and construction environments among

others and used to control motor speeds torques and positions and may be AC or DC driven Servo

motors are used in many applications including machine tools micro-positioning and robotics among

many other types of machinery such as conveyors or spindle drive systems The controller commonly

integrated with the drive circuits supplies the control signals to the drive Servo drives are also known

as servomotor amplifiers

Stepper Stepper Motor Controllers and Drives are electronic devices that modify the input power by adjusting

the constant or alternating current source to a pulsed or stepped current output

Key specifications include the intended application motor type drive

operating mode loop system power rating output signal type

communication interface as well as electrical specifications

Stepper motor controllers and drives are used primarily in motion

control applications in manufacturing and construction environments

among others and used to control motor speeds torques and

position They are used in many applications including machine tools

micro-positioning and robotics among many other types of

machinery such as conveyors or OEM equipment The controller

commonly integrated with the drive circuits supplies the control signals to the drive Stepper drives are

also known as pulse drives and step amplifiers Stepper controllers are also known as motor indexers

Applications and Industries

Unlike servomotors and steppers most AC and DC motors donrsquot require controllers or drives other than

the simplest motor starters and similar protective devices AC motor drives are used when speed control

of an AC motor is desirable because controlling speed in an AC induction motor is not normally donemdash

once a motor has been specified (by number of poles) the operating speed is stated on the nameplate

Brushed DC motors on the other hand are fundamentally speed controllable by merely varying the

voltage going to the motor rotor and field This can be accomplished with a simple rheostat no

controller or drive is necessary Newer brushless DC motors are not mechanically commutated and

hence require controllers and drives to commutate the magnetic field electronically Servomotors and

steppers because they are positioning devices as opposed to rotary motion machines also require

controllers and drivers for their operation

AC motors drives are used to control the speeds of motors that drive pumps fans etc where traditional

valves or dampers might otherwise be used to throttle the flow AC motor drives are used to increase

efficiency by setting pump fan etc speed to exactly match requirements

DC motor drives are used to control permanent magnet DC motors running from AC sources DC motors

have very good low speed torque making them especially suited to winches cranes etc where loads

have to be lifted without a ldquorunning startrdquo Before the advent of electronic DC controls DC motors we

often coupled as motor-generator sets to produce DC current via AC

induction motors

Servomotor controllers and drives rely on feedback from the

servomotors to control position velocity acceleration etc Servomotor

manufacturers generally supply drives that work with their motors

While steppers donrsquot require a feedback loop some use one Stepper

motor makers also usually supply drives for their specific motors Most

servo- and stepper-motor manufacturers provide charts as guides to

which motors will work with which drives

Considerations Choosing motor controllers and drives starts with knowing the motor type Corresponding sub-

categories then align with this basic information

Deciding to use AC drives for induction motors is often an economic decision based on operating

characteristics at specific installations how often the pump or fan is running against throttled valves or

louvered ducts At least one manufacturer offers a calculator (see below) to help determine energy

savings of AC drives based on specific operating scenarios Motors designed for use with variable speed

drives are typically rated for inverter duty

Another consideration for AC drives is the nature of the application with constant torque and variable

torque being major divisions For variable torque applications such as centrifugal fans torque

requirements vary with motor speed For constant torque applications such as conveyors torque

requirements are the same regardless of motor speed AC drives are usually designed for either variable

or constant speed applications

Brushed DC motors running off AC current usually are driven using thyristor-based bridge rectifiers ehich

permit AC current to flow to the motor in one direction only replicating a DC power source More can

be found in the references below Vendors such as Baldor provide DC controls for one way and

regenerative applications for DC motor horsepowers up to 5 and through its parent company (ABB)

offers DC drives up to 3000 HP One-way drives usually require a brake for stopping the motor while

regenerative drives can run the motor in either direction and so provide stopping force by reversing

Generated power is usually bled off through reversing resistors

Brushed DC motors operating on DC systems such as found on electric pallet jacks also use controls for

speed and directional changes Brushless DC or permanent magnet motors also require controllers to

electronically commutate their magnetic fields

Servomotors can be of AC or DC types with DC available as brush and brushless types In all instances

they require controls because they are feedback devices Linear motors are generally servo-based and

require controls too

Stepper motors generally do not require feedback but must be ldquohomedrdquo upon powering up so that the

motor knows where it is From there it counts steps to keep track of position Some steppers piggyback

their drives directly on the motor frames

Important Attributes

Semiconductor Device Generally speaking IGBTs and SCRs are used for medium and high voltage devices while MOSFETs are

used in low power applications

Motor Input Phase Motors are generally single or three phase machines referring to the phase of the alternating current

that supplies them Stepper motors are an exception in this regard because phase refers to the

architecture of the stepper motor itself generally described as two or five phase Oriental Motors has a

nice write up discussing the difference cited below

Enclosure Electrical enclosures are specified in accordance with NEMA or IEC criteria for environmental and ingress

protection

Drive Operating Mode As discussed above AC drives are generally designed either as constant torque or variable torque

depending on the application

Related Product Categories

Motors see our Motors Buying Guide

Motor Starters see our Motor Starters Buying Guide

Resources

General Trade groups httpwwwsmmaorgindexhtm httpwwwmotioncontrolonlineorgi4apagesindexcfmpageid=3283 A pump and fan energy saving calculator for evaluating AC variable speed drives httpwwwrockwellenergycalccom A technical discussion of DC motors and drives httpcmsappsseasiemenscomsteppdfsdc_drivespdf Two-phase v five-phase stepper motor comparison httpwwworientalmotorcomtechnologyarticles2phase-v-5phasehtml

Manufacturers and Suppliers httpcatalogorientalmotorcom httpproductsautonicsonlinecomcategorymotion-devices httpcataloge-jpccom httprepair-searchschneiderelectricrepaircomcategoryby-product-type httpservolinearcomthomasnet-navigatorcomproductservo-drive-componentspositioning-controller httpmotionsystemspi-usaus httpbaldorthomasnetcom httpcatalogjamiesonequipmentcomcategoryrs-motor-controls-and-gear-reducers-motor-controls httpcataloge-jpccom httpboydelectricalstagethomasnet-navigatorcom httpcookindustrialthomasnetcomviewitemsindustrial-parts-vfd-s-inverters-cerus-invertersampbc=100|1025|1027 httpcatalogkofflercomcategoryvariable-frequency-drivesampbc=1007C1279 httpwwwgamainccomrc httpautovacthomasnet-navigatorcomcategoryadvanced-motor-controls-software httpdc-drives-motorsgrahammotorsandcontrolscomcategorydc-motor-controllers httpbodineelethomasnetcom httpproductsfifepearcecomcategoryproduct-catalog httpspindle-catalogtdmusaspindlescomcategoryhigh-speed-motor-drives httpcatalogpowertechcontrolscomcategorys-abb-control-abb-drives-abb-low-voltage-ac-drives httppumpsrapidservicecomcategoryyaskawa-vfd-drives

MOTOR CONTROLLERS AND DRIVES A ThomasNet Buying Guide

Motor Controllers and Drives are electrical or electronic

devices that regulate motor speed torque and position

outputs The drive modifies the power input to the motor to achieve the desired output The controller

circuits are commonly integrated with the drive circuits as one stand-alone unit thus the terms motor

drive and motor controller are frequently used interchangeably There are four basic motor controller

and drive types AC DC servo and stepper each having an input power type modified to a desired

output function to match with an application

Motor Controller and Drive Types

AC AC Motor Controllers and Drives are electronic devices that modify

the input power to motors by typically adjusting the frequency of the

power to the motor for the purpose of regulating the output speed

and torque Key specifications include the intended application drive

operating mode motor type inverter type loop system voltage

classification power rating communication interface as well as

input and output electrical specifications AC motor controllers and

drives are used primarily in process applications to control the speed

of pumps fans blowers etc They are known as variable speed

drives adjustable frequency drives or AC inverters The controller

commonly integrated with the drive circuits supplies the control

signals to the drive

DC DC Motor Controllers and Drives are electrical devices that modify the

input power by adjusting the constant or alternating current source to a

pulsed direct current output of varying pulse duration or frequency Key

specifications include the intended application drive operating mode

motor type loop system voltage classification power rating output signal

type communication interface as well as input and output electrical

specifications DC motor controllers and drives are used primarily to

control motor speeds and torques for machine tools electric vehicles

pumps etc The controller commonly integrated with the drive circuits supplies the control signals to

the drive

Servomotor Servo Motor Controllers and Drives are electronic devices that modify

the input power by adjusting the constant or alternating current source

to a pulsed current output of varying pulse duration or frequency Key

specifications include the intended application motor type drive

operating mode loop system power rating output signal type

communication interface as well as electrical specifications Servo

motor controllers and drives are used primarily in motion control

applications in manufacturing and construction environments among

others and used to control motor speeds torques and positions and may be AC or DC driven Servo

motors are used in many applications including machine tools micro-positioning and robotics among

many other types of machinery such as conveyors or spindle drive systems The controller commonly

integrated with the drive circuits supplies the control signals to the drive Servo drives are also known

as servomotor amplifiers

Stepper Stepper Motor Controllers and Drives are electronic devices that modify the input power by adjusting

the constant or alternating current source to a pulsed or stepped current output

Key specifications include the intended application motor type drive

operating mode loop system power rating output signal type

communication interface as well as electrical specifications

Stepper motor controllers and drives are used primarily in motion

control applications in manufacturing and construction environments

among others and used to control motor speeds torques and

position They are used in many applications including machine tools

micro-positioning and robotics among many other types of

machinery such as conveyors or OEM equipment The controller

commonly integrated with the drive circuits supplies the control signals to the drive Stepper drives are

also known as pulse drives and step amplifiers Stepper controllers are also known as motor indexers

Applications and Industries

Unlike servomotors and steppers most AC and DC motors donrsquot require controllers or drives other than

the simplest motor starters and similar protective devices AC motor drives are used when speed control

of an AC motor is desirable because controlling speed in an AC induction motor is not normally donemdash

once a motor has been specified (by number of poles) the operating speed is stated on the nameplate

Brushed DC motors on the other hand are fundamentally speed controllable by merely varying the

voltage going to the motor rotor and field This can be accomplished with a simple rheostat no

controller or drive is necessary Newer brushless DC motors are not mechanically commutated and

hence require controllers and drives to commutate the magnetic field electronically Servomotors and

steppers because they are positioning devices as opposed to rotary motion machines also require

controllers and drivers for their operation

AC motors drives are used to control the speeds of motors that drive pumps fans etc where traditional

valves or dampers might otherwise be used to throttle the flow AC motor drives are used to increase

efficiency by setting pump fan etc speed to exactly match requirements

DC motor drives are used to control permanent magnet DC motors running from AC sources DC motors

have very good low speed torque making them especially suited to winches cranes etc where loads

have to be lifted without a ldquorunning startrdquo Before the advent of electronic DC controls DC motors we

often coupled as motor-generator sets to produce DC current via AC

induction motors

Servomotor controllers and drives rely on feedback from the

servomotors to control position velocity acceleration etc Servomotor

manufacturers generally supply drives that work with their motors

While steppers donrsquot require a feedback loop some use one Stepper

motor makers also usually supply drives for their specific motors Most

servo- and stepper-motor manufacturers provide charts as guides to

which motors will work with which drives

Considerations Choosing motor controllers and drives starts with knowing the motor type Corresponding sub-

categories then align with this basic information

Deciding to use AC drives for induction motors is often an economic decision based on operating

characteristics at specific installations how often the pump or fan is running against throttled valves or

louvered ducts At least one manufacturer offers a calculator (see below) to help determine energy

savings of AC drives based on specific operating scenarios Motors designed for use with variable speed

drives are typically rated for inverter duty

Another consideration for AC drives is the nature of the application with constant torque and variable

torque being major divisions For variable torque applications such as centrifugal fans torque

requirements vary with motor speed For constant torque applications such as conveyors torque

requirements are the same regardless of motor speed AC drives are usually designed for either variable

or constant speed applications

Brushed DC motors running off AC current usually are driven using thyristor-based bridge rectifiers ehich

permit AC current to flow to the motor in one direction only replicating a DC power source More can

be found in the references below Vendors such as Baldor provide DC controls for one way and

regenerative applications for DC motor horsepowers up to 5 and through its parent company (ABB)

offers DC drives up to 3000 HP One-way drives usually require a brake for stopping the motor while

regenerative drives can run the motor in either direction and so provide stopping force by reversing

Generated power is usually bled off through reversing resistors

Brushed DC motors operating on DC systems such as found on electric pallet jacks also use controls for

speed and directional changes Brushless DC or permanent magnet motors also require controllers to

electronically commutate their magnetic fields

Servomotors can be of AC or DC types with DC available as brush and brushless types In all instances

they require controls because they are feedback devices Linear motors are generally servo-based and

require controls too

Stepper motors generally do not require feedback but must be ldquohomedrdquo upon powering up so that the

motor knows where it is From there it counts steps to keep track of position Some steppers piggyback

their drives directly on the motor frames

Important Attributes

Semiconductor Device Generally speaking IGBTs and SCRs are used for medium and high voltage devices while MOSFETs are

used in low power applications

Motor Input Phase Motors are generally single or three phase machines referring to the phase of the alternating current

that supplies them Stepper motors are an exception in this regard because phase refers to the

architecture of the stepper motor itself generally described as two or five phase Oriental Motors has a

nice write up discussing the difference cited below

Enclosure Electrical enclosures are specified in accordance with NEMA or IEC criteria for environmental and ingress

protection

Drive Operating Mode As discussed above AC drives are generally designed either as constant torque or variable torque

depending on the application

Related Product Categories

Motors see our Motors Buying Guide

Motor Starters see our Motor Starters Buying Guide

Resources

General Trade groups httpwwwsmmaorgindexhtm httpwwwmotioncontrolonlineorgi4apagesindexcfmpageid=3283 A pump and fan energy saving calculator for evaluating AC variable speed drives httpwwwrockwellenergycalccom A technical discussion of DC motors and drives httpcmsappsseasiemenscomsteppdfsdc_drivespdf Two-phase v five-phase stepper motor comparison httpwwworientalmotorcomtechnologyarticles2phase-v-5phasehtml

Manufacturers and Suppliers httpcatalogorientalmotorcom httpproductsautonicsonlinecomcategorymotion-devices httpcataloge-jpccom httprepair-searchschneiderelectricrepaircomcategoryby-product-type httpservolinearcomthomasnet-navigatorcomproductservo-drive-componentspositioning-controller httpmotionsystemspi-usaus httpbaldorthomasnetcom httpcatalogjamiesonequipmentcomcategoryrs-motor-controls-and-gear-reducers-motor-controls httpcataloge-jpccom httpboydelectricalstagethomasnet-navigatorcom httpcookindustrialthomasnetcomviewitemsindustrial-parts-vfd-s-inverters-cerus-invertersampbc=100|1025|1027 httpcatalogkofflercomcategoryvariable-frequency-drivesampbc=1007C1279 httpwwwgamainccomrc httpautovacthomasnet-navigatorcomcategoryadvanced-motor-controls-software httpdc-drives-motorsgrahammotorsandcontrolscomcategorydc-motor-controllers httpbodineelethomasnetcom httpproductsfifepearcecomcategoryproduct-catalog httpspindle-catalogtdmusaspindlescomcategoryhigh-speed-motor-drives httpcatalogpowertechcontrolscomcategorys-abb-control-abb-drives-abb-low-voltage-ac-drives httppumpsrapidservicecomcategoryyaskawa-vfd-drives

pumps etc The controller commonly integrated with the drive circuits supplies the control signals to

the drive

Servomotor Servo Motor Controllers and Drives are electronic devices that modify

the input power by adjusting the constant or alternating current source

to a pulsed current output of varying pulse duration or frequency Key

specifications include the intended application motor type drive

operating mode loop system power rating output signal type

communication interface as well as electrical specifications Servo

motor controllers and drives are used primarily in motion control

applications in manufacturing and construction environments among

others and used to control motor speeds torques and positions and may be AC or DC driven Servo

motors are used in many applications including machine tools micro-positioning and robotics among

many other types of machinery such as conveyors or spindle drive systems The controller commonly

integrated with the drive circuits supplies the control signals to the drive Servo drives are also known

as servomotor amplifiers

Stepper Stepper Motor Controllers and Drives are electronic devices that modify the input power by adjusting

the constant or alternating current source to a pulsed or stepped current output

Key specifications include the intended application motor type drive

operating mode loop system power rating output signal type

communication interface as well as electrical specifications

Stepper motor controllers and drives are used primarily in motion

control applications in manufacturing and construction environments

among others and used to control motor speeds torques and

position They are used in many applications including machine tools

micro-positioning and robotics among many other types of

machinery such as conveyors or OEM equipment The controller

commonly integrated with the drive circuits supplies the control signals to the drive Stepper drives are

also known as pulse drives and step amplifiers Stepper controllers are also known as motor indexers

Applications and Industries

Unlike servomotors and steppers most AC and DC motors donrsquot require controllers or drives other than

the simplest motor starters and similar protective devices AC motor drives are used when speed control

of an AC motor is desirable because controlling speed in an AC induction motor is not normally donemdash

once a motor has been specified (by number of poles) the operating speed is stated on the nameplate

Brushed DC motors on the other hand are fundamentally speed controllable by merely varying the

voltage going to the motor rotor and field This can be accomplished with a simple rheostat no

controller or drive is necessary Newer brushless DC motors are not mechanically commutated and

hence require controllers and drives to commutate the magnetic field electronically Servomotors and

steppers because they are positioning devices as opposed to rotary motion machines also require

controllers and drivers for their operation

AC motors drives are used to control the speeds of motors that drive pumps fans etc where traditional

valves or dampers might otherwise be used to throttle the flow AC motor drives are used to increase

efficiency by setting pump fan etc speed to exactly match requirements

DC motor drives are used to control permanent magnet DC motors running from AC sources DC motors

have very good low speed torque making them especially suited to winches cranes etc where loads

have to be lifted without a ldquorunning startrdquo Before the advent of electronic DC controls DC motors we

often coupled as motor-generator sets to produce DC current via AC

induction motors

Servomotor controllers and drives rely on feedback from the

servomotors to control position velocity acceleration etc Servomotor

manufacturers generally supply drives that work with their motors

While steppers donrsquot require a feedback loop some use one Stepper

motor makers also usually supply drives for their specific motors Most

servo- and stepper-motor manufacturers provide charts as guides to

which motors will work with which drives

Considerations Choosing motor controllers and drives starts with knowing the motor type Corresponding sub-

categories then align with this basic information

Deciding to use AC drives for induction motors is often an economic decision based on operating

characteristics at specific installations how often the pump or fan is running against throttled valves or

louvered ducts At least one manufacturer offers a calculator (see below) to help determine energy

savings of AC drives based on specific operating scenarios Motors designed for use with variable speed

drives are typically rated for inverter duty

Another consideration for AC drives is the nature of the application with constant torque and variable

torque being major divisions For variable torque applications such as centrifugal fans torque

requirements vary with motor speed For constant torque applications such as conveyors torque

requirements are the same regardless of motor speed AC drives are usually designed for either variable

or constant speed applications

Brushed DC motors running off AC current usually are driven using thyristor-based bridge rectifiers ehich

permit AC current to flow to the motor in one direction only replicating a DC power source More can

be found in the references below Vendors such as Baldor provide DC controls for one way and

regenerative applications for DC motor horsepowers up to 5 and through its parent company (ABB)

offers DC drives up to 3000 HP One-way drives usually require a brake for stopping the motor while

regenerative drives can run the motor in either direction and so provide stopping force by reversing

Generated power is usually bled off through reversing resistors

Brushed DC motors operating on DC systems such as found on electric pallet jacks also use controls for

speed and directional changes Brushless DC or permanent magnet motors also require controllers to

electronically commutate their magnetic fields

Servomotors can be of AC or DC types with DC available as brush and brushless types In all instances

they require controls because they are feedback devices Linear motors are generally servo-based and

require controls too

Stepper motors generally do not require feedback but must be ldquohomedrdquo upon powering up so that the

motor knows where it is From there it counts steps to keep track of position Some steppers piggyback

their drives directly on the motor frames

Important Attributes

Semiconductor Device Generally speaking IGBTs and SCRs are used for medium and high voltage devices while MOSFETs are

used in low power applications

Motor Input Phase Motors are generally single or three phase machines referring to the phase of the alternating current

that supplies them Stepper motors are an exception in this regard because phase refers to the

architecture of the stepper motor itself generally described as two or five phase Oriental Motors has a

nice write up discussing the difference cited below

Enclosure Electrical enclosures are specified in accordance with NEMA or IEC criteria for environmental and ingress

protection

Drive Operating Mode As discussed above AC drives are generally designed either as constant torque or variable torque

depending on the application

Related Product Categories

Motors see our Motors Buying Guide

Motor Starters see our Motor Starters Buying Guide

Resources

General Trade groups httpwwwsmmaorgindexhtm httpwwwmotioncontrolonlineorgi4apagesindexcfmpageid=3283 A pump and fan energy saving calculator for evaluating AC variable speed drives httpwwwrockwellenergycalccom A technical discussion of DC motors and drives httpcmsappsseasiemenscomsteppdfsdc_drivespdf Two-phase v five-phase stepper motor comparison httpwwworientalmotorcomtechnologyarticles2phase-v-5phasehtml

Manufacturers and Suppliers httpcatalogorientalmotorcom httpproductsautonicsonlinecomcategorymotion-devices httpcataloge-jpccom httprepair-searchschneiderelectricrepaircomcategoryby-product-type httpservolinearcomthomasnet-navigatorcomproductservo-drive-componentspositioning-controller httpmotionsystemspi-usaus httpbaldorthomasnetcom httpcatalogjamiesonequipmentcomcategoryrs-motor-controls-and-gear-reducers-motor-controls httpcataloge-jpccom httpboydelectricalstagethomasnet-navigatorcom httpcookindustrialthomasnetcomviewitemsindustrial-parts-vfd-s-inverters-cerus-invertersampbc=100|1025|1027 httpcatalogkofflercomcategoryvariable-frequency-drivesampbc=1007C1279 httpwwwgamainccomrc httpautovacthomasnet-navigatorcomcategoryadvanced-motor-controls-software httpdc-drives-motorsgrahammotorsandcontrolscomcategorydc-motor-controllers httpbodineelethomasnetcom httpproductsfifepearcecomcategoryproduct-catalog httpspindle-catalogtdmusaspindlescomcategoryhigh-speed-motor-drives httpcatalogpowertechcontrolscomcategorys-abb-control-abb-drives-abb-low-voltage-ac-drives httppumpsrapidservicecomcategoryyaskawa-vfd-drives

hence require controllers and drives to commutate the magnetic field electronically Servomotors and

steppers because they are positioning devices as opposed to rotary motion machines also require

controllers and drivers for their operation

AC motors drives are used to control the speeds of motors that drive pumps fans etc where traditional

valves or dampers might otherwise be used to throttle the flow AC motor drives are used to increase

efficiency by setting pump fan etc speed to exactly match requirements

DC motor drives are used to control permanent magnet DC motors running from AC sources DC motors

have very good low speed torque making them especially suited to winches cranes etc where loads

have to be lifted without a ldquorunning startrdquo Before the advent of electronic DC controls DC motors we

often coupled as motor-generator sets to produce DC current via AC

induction motors

Servomotor controllers and drives rely on feedback from the

servomotors to control position velocity acceleration etc Servomotor

manufacturers generally supply drives that work with their motors

While steppers donrsquot require a feedback loop some use one Stepper

motor makers also usually supply drives for their specific motors Most

servo- and stepper-motor manufacturers provide charts as guides to

which motors will work with which drives

Considerations Choosing motor controllers and drives starts with knowing the motor type Corresponding sub-

categories then align with this basic information

Deciding to use AC drives for induction motors is often an economic decision based on operating

characteristics at specific installations how often the pump or fan is running against throttled valves or

louvered ducts At least one manufacturer offers a calculator (see below) to help determine energy

savings of AC drives based on specific operating scenarios Motors designed for use with variable speed

drives are typically rated for inverter duty

Another consideration for AC drives is the nature of the application with constant torque and variable

torque being major divisions For variable torque applications such as centrifugal fans torque

requirements vary with motor speed For constant torque applications such as conveyors torque

requirements are the same regardless of motor speed AC drives are usually designed for either variable

or constant speed applications

Brushed DC motors running off AC current usually are driven using thyristor-based bridge rectifiers ehich

permit AC current to flow to the motor in one direction only replicating a DC power source More can

be found in the references below Vendors such as Baldor provide DC controls for one way and

regenerative applications for DC motor horsepowers up to 5 and through its parent company (ABB)

offers DC drives up to 3000 HP One-way drives usually require a brake for stopping the motor while

regenerative drives can run the motor in either direction and so provide stopping force by reversing

Generated power is usually bled off through reversing resistors

Brushed DC motors operating on DC systems such as found on electric pallet jacks also use controls for

speed and directional changes Brushless DC or permanent magnet motors also require controllers to

electronically commutate their magnetic fields

Servomotors can be of AC or DC types with DC available as brush and brushless types In all instances

they require controls because they are feedback devices Linear motors are generally servo-based and

require controls too

Stepper motors generally do not require feedback but must be ldquohomedrdquo upon powering up so that the

motor knows where it is From there it counts steps to keep track of position Some steppers piggyback

their drives directly on the motor frames

Important Attributes

Semiconductor Device Generally speaking IGBTs and SCRs are used for medium and high voltage devices while MOSFETs are

used in low power applications

Motor Input Phase Motors are generally single or three phase machines referring to the phase of the alternating current

that supplies them Stepper motors are an exception in this regard because phase refers to the

architecture of the stepper motor itself generally described as two or five phase Oriental Motors has a

nice write up discussing the difference cited below

Enclosure Electrical enclosures are specified in accordance with NEMA or IEC criteria for environmental and ingress

protection

Drive Operating Mode As discussed above AC drives are generally designed either as constant torque or variable torque

depending on the application

Related Product Categories

Motors see our Motors Buying Guide

Motor Starters see our Motor Starters Buying Guide

Resources

General Trade groups httpwwwsmmaorgindexhtm httpwwwmotioncontrolonlineorgi4apagesindexcfmpageid=3283 A pump and fan energy saving calculator for evaluating AC variable speed drives httpwwwrockwellenergycalccom A technical discussion of DC motors and drives httpcmsappsseasiemenscomsteppdfsdc_drivespdf Two-phase v five-phase stepper motor comparison httpwwworientalmotorcomtechnologyarticles2phase-v-5phasehtml

Manufacturers and Suppliers httpcatalogorientalmotorcom httpproductsautonicsonlinecomcategorymotion-devices httpcataloge-jpccom httprepair-searchschneiderelectricrepaircomcategoryby-product-type httpservolinearcomthomasnet-navigatorcomproductservo-drive-componentspositioning-controller httpmotionsystemspi-usaus httpbaldorthomasnetcom httpcatalogjamiesonequipmentcomcategoryrs-motor-controls-and-gear-reducers-motor-controls httpcataloge-jpccom httpboydelectricalstagethomasnet-navigatorcom httpcookindustrialthomasnetcomviewitemsindustrial-parts-vfd-s-inverters-cerus-invertersampbc=100|1025|1027 httpcatalogkofflercomcategoryvariable-frequency-drivesampbc=1007C1279 httpwwwgamainccomrc httpautovacthomasnet-navigatorcomcategoryadvanced-motor-controls-software httpdc-drives-motorsgrahammotorsandcontrolscomcategorydc-motor-controllers httpbodineelethomasnetcom httpproductsfifepearcecomcategoryproduct-catalog httpspindle-catalogtdmusaspindlescomcategoryhigh-speed-motor-drives httpcatalogpowertechcontrolscomcategorys-abb-control-abb-drives-abb-low-voltage-ac-drives httppumpsrapidservicecomcategoryyaskawa-vfd-drives

regenerative drives can run the motor in either direction and so provide stopping force by reversing

Generated power is usually bled off through reversing resistors

Brushed DC motors operating on DC systems such as found on electric pallet jacks also use controls for

speed and directional changes Brushless DC or permanent magnet motors also require controllers to

electronically commutate their magnetic fields

Servomotors can be of AC or DC types with DC available as brush and brushless types In all instances

they require controls because they are feedback devices Linear motors are generally servo-based and

require controls too

Stepper motors generally do not require feedback but must be ldquohomedrdquo upon powering up so that the

motor knows where it is From there it counts steps to keep track of position Some steppers piggyback

their drives directly on the motor frames

Important Attributes

Semiconductor Device Generally speaking IGBTs and SCRs are used for medium and high voltage devices while MOSFETs are

used in low power applications

Motor Input Phase Motors are generally single or three phase machines referring to the phase of the alternating current

that supplies them Stepper motors are an exception in this regard because phase refers to the

architecture of the stepper motor itself generally described as two or five phase Oriental Motors has a

nice write up discussing the difference cited below

Enclosure Electrical enclosures are specified in accordance with NEMA or IEC criteria for environmental and ingress

protection

Drive Operating Mode As discussed above AC drives are generally designed either as constant torque or variable torque

depending on the application

Related Product Categories

Motors see our Motors Buying Guide

Motor Starters see our Motor Starters Buying Guide

Resources

General Trade groups httpwwwsmmaorgindexhtm httpwwwmotioncontrolonlineorgi4apagesindexcfmpageid=3283 A pump and fan energy saving calculator for evaluating AC variable speed drives httpwwwrockwellenergycalccom A technical discussion of DC motors and drives httpcmsappsseasiemenscomsteppdfsdc_drivespdf Two-phase v five-phase stepper motor comparison httpwwworientalmotorcomtechnologyarticles2phase-v-5phasehtml

Manufacturers and Suppliers httpcatalogorientalmotorcom httpproductsautonicsonlinecomcategorymotion-devices httpcataloge-jpccom httprepair-searchschneiderelectricrepaircomcategoryby-product-type httpservolinearcomthomasnet-navigatorcomproductservo-drive-componentspositioning-controller httpmotionsystemspi-usaus httpbaldorthomasnetcom httpcatalogjamiesonequipmentcomcategoryrs-motor-controls-and-gear-reducers-motor-controls httpcataloge-jpccom httpboydelectricalstagethomasnet-navigatorcom httpcookindustrialthomasnetcomviewitemsindustrial-parts-vfd-s-inverters-cerus-invertersampbc=100|1025|1027 httpcatalogkofflercomcategoryvariable-frequency-drivesampbc=1007C1279 httpwwwgamainccomrc httpautovacthomasnet-navigatorcomcategoryadvanced-motor-controls-software httpdc-drives-motorsgrahammotorsandcontrolscomcategorydc-motor-controllers httpbodineelethomasnetcom httpproductsfifepearcecomcategoryproduct-catalog httpspindle-catalogtdmusaspindlescomcategoryhigh-speed-motor-drives httpcatalogpowertechcontrolscomcategorys-abb-control-abb-drives-abb-low-voltage-ac-drives httppumpsrapidservicecomcategoryyaskawa-vfd-drives

Resources

General Trade groups httpwwwsmmaorgindexhtm httpwwwmotioncontrolonlineorgi4apagesindexcfmpageid=3283 A pump and fan energy saving calculator for evaluating AC variable speed drives httpwwwrockwellenergycalccom A technical discussion of DC motors and drives httpcmsappsseasiemenscomsteppdfsdc_drivespdf Two-phase v five-phase stepper motor comparison httpwwworientalmotorcomtechnologyarticles2phase-v-5phasehtml

Manufacturers and Suppliers httpcatalogorientalmotorcom httpproductsautonicsonlinecomcategorymotion-devices httpcataloge-jpccom httprepair-searchschneiderelectricrepaircomcategoryby-product-type httpservolinearcomthomasnet-navigatorcomproductservo-drive-componentspositioning-controller httpmotionsystemspi-usaus httpbaldorthomasnetcom httpcatalogjamiesonequipmentcomcategoryrs-motor-controls-and-gear-reducers-motor-controls httpcataloge-jpccom httpboydelectricalstagethomasnet-navigatorcom httpcookindustrialthomasnetcomviewitemsindustrial-parts-vfd-s-inverters-cerus-invertersampbc=100|1025|1027 httpcatalogkofflercomcategoryvariable-frequency-drivesampbc=1007C1279 httpwwwgamainccomrc httpautovacthomasnet-navigatorcomcategoryadvanced-motor-controls-software httpdc-drives-motorsgrahammotorsandcontrolscomcategorydc-motor-controllers httpbodineelethomasnetcom httpproductsfifepearcecomcategoryproduct-catalog httpspindle-catalogtdmusaspindlescomcategoryhigh-speed-motor-drives httpcatalogpowertechcontrolscomcategorys-abb-control-abb-drives-abb-low-voltage-ac-drives httppumpsrapidservicecomcategoryyaskawa-vfd-drives