nippon pulse america unraveling the mystery of stepper motor technology presentation

NPM

Unraveling The Mystery of Unraveling The Mystery of Stepper Motor TechnologyStepper Motor Technology

JeramJeraméé Chamberlain Chamberlain

Nippon Pulse America, Inc., USANippon Pulse America, Inc., USA

ELECTROMATEToll Free Phone (877) SERVO98

Toll Free Fax (877) SERV099www.electromate.com

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NPM What is a Open LoopWhat is a Open Loop Stepper Motor System?Stepper Motor System?

What Are Stepper Motors?What Are Stepper Motors?

How Do Stepper Motors Work?How Do Stepper Motors Work?

Troubleshoot & Test Stepper MotorsTroubleshoot & Test Stepper Motors



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NPM Basic Stepper ApplicationBasic Stepper Application



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NPM Stepper Motor CoilStepper Motor Coil

NN

SS

NN

SS●● PHASE BPHASE B

PHASE APHASE A

PHASE APHASE A

PHASE BPHASE B



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NPM

NN

SS

NN

SS

●●

PHASE APHASE A

PHASE BPHASE B PHASE BPHASE B

PHASE APHASE A

STEP 1STEP 1

SS

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PHASE APHASE A


PHASE APHASE A

STEP 3STEP 3

NNSS NN SS●●

PHASE APHASE A


PHASE APHASE A

STEP 4STEP 4

NN SSNNSS ●●

PHASE APHASE A


PHASE APHASE A

STEP 2STEP 2

One PhaseOne Phase Step SequenceStep Sequence

Two PhaseTwo Phase Stepper MotorStepper Motor



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NPM Types of Stepper MotorsTypes of Stepper Motors

PermanentPermanent--Magnet (PM)Magnet (PM)••

PM rotor & electromagnetic coilPM rotor & electromagnetic coil

Variable Reluctance (VR)Variable Reluctance (VR)••

No PM, no residual torqueNo PM, no residual torque

Hybrid Hybrid ––

NEMA SizingNEMA Sizing••

Combined PM & VR TechnologyCombined PM & VR Technology



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NPM Cross Section of A TwoCross Section of A Two Phase Hybrid MotorPhase Hybrid Motor



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NPM PM & Hybrid Stepper MotorsPM & Hybrid Stepper Motors



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NPM Bipolar Coil WindingBipolar Coil Winding

Current flow and electromagnetic Current flow and electromagnetic polarity is reverses in the windingspolarity is reverses in the windings

Each phase Each phase is a single is a single windingwinding



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NPM Unipolar Coil WindingUnipolar Coil Winding

Current flow and electromagnetic polarity is Current flow and electromagnetic polarity is NOT reversed in the windings. Polarity NOT reversed in the windings. Polarity comes from alternately energized windingscomes from alternately energized windings

Sometimes Sometimes calledcalled

fourfour--phase phase stepperssteppers



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NPM Motors Need MaintenanceMotors Need Maintenance Steppers Steppers –– Not So MuchNot So Much

Stalled motors burn upStalled motors burn up••

Steppers operate in stall conditionSteppers operate in stall condition

Most brushes go badMost brushes go bad••

Steppers are brushlessSteppers are brushless

All bearings go badAll bearings go bad••

Quality Stepper bearings are Quality Stepper bearings are rated from 90rated from 90--100K hours100K hours

People break themPeople break them••

Hammers donHammers don’’t fix Stepperst fix Steppers



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NPM Ohmmeter Test With SteppersOhmmeter Test With SteppersBipolarBipolar

Always 4 leadsAlways 4 leads

Resistance is Resistance is the same in the same in both windings both windings and both and both directionsdirections

Some 8 lead motors can be connected Some 8 lead motors can be connected as bipolaras bipolar ELECTROMATE

Toll Free Phone (877) SERVO98Toll Free Fax (877) SERV099

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NPM Ohmmeter Test With SteppersOhmmeter Test With SteppersUnipolarUnipolar

5 or 6 leads5 or 6 leads

Resistance from Resistance from each phase to each phase to Common is the Common is the same in both same in both directionsdirections

If 5 leads, two commons connectedIf 5 leads, two commons connected

Some 8 lead motors can be UnipolarSome 8 lead motors can be UnipolarELECTROMATEToll Free Phone (877) SERVO98


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NPM Unipolar Windings & Wire ColorsUnipolar Windings & Wire Colors



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NPM Bipolar Windings & Wire ColorsBipolar Windings & Wire Colors



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NPM Stepper Motor Electronic SystemStepper Motor Electronic System

CPU, Controller, Sequencer, DriverCPU, Controller, Sequencer, Driver

One or more parts can be combined, One or more parts can be combined, based on motion complexitybased on motion complexity ELECTROMATE


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NPM Controller Receives & CoordinatesController Receives & Coordinates

A dedicated controller generates A dedicated controller generates motion profiles that produce smoother motion profiles that produce smoother motor operation than just with a CPU.motor operation than just with a CPU.ELECTROMATE


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NPM Controller Manages & InterpolatesController Manages & Interpolates

Some controllers provide interpolation Some controllers provide interpolation between motors to produce smooth between motors to produce smooth XYZ motions XYZ motions ––

CNC MachinesCNC Machines ELECTROMATE


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NPM Two Outputs Types to SequencerTwo Outputs Types to Sequencer

Pulse & Direction Pulse & Direction ––

Speed & RotationSpeed & Rotation

CW/CCW CW/CCW ––

Speed & RotationSpeed & Rotation ELECTROMATEToll Free Phone (877) SERVO98


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NPM One Controller One Controller –– Two Output TypesTwo Output Types

Pulse & Direction Pulse & Direction –– Speed & RotationSpeed & Rotation

CW/CCW CW/CCW ––

Speed & Speed & RotationRotation

Pulse & Direction is the most Pulse & Direction is the most common format used in the USAcommon format used in the USA

PCL6045B can output both formatsPCL6045B can output both formatsELECTROMATE


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NPM Stepper Motor SequencersStepper Motor Sequencers

Sequencers read speed and direction Sequencers read speed and direction from controller and deliver excitation from controller and deliver excitation sequence to the driversequence to the driver



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NPM Bipolar Stepper DriversBipolar Stepper Drivers

When Q1a and When Q1a and Q4a (green) Q4a (green) are on, current are on, current flows in one flows in one directiondirection

When Q2a and When Q2a and Q3a (red) are Q3a (red) are turned on, turned on, current flow is current flow is reversedreversed



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NPM Unipolar Stepper DriversUnipolar Stepper Drivers

Half the drive Half the drive electronics of electronics of bipolar, and bipolar, and 30% less torque30% less torque

However, However, unipolar coils unipolar coils allow a higher allow a higher pulse rate than pulse rate than bipolar, before bipolar, before becoming becoming saturated.saturated. ELECTROMATE


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NPM Constant Current Constant Current -- Constant VoltageConstant Voltage



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NPM Current Lags Voltage in an InductorCurrent Lags Voltage in an Inductor

Torque from stepper Torque from stepper motors is generated by motors is generated by current, not voltagecurrent, not voltage

PWM or Chopper drive PWM or Chopper drive manages current manages current through a switch, through a switch, applied at higher applied at higher voltages to induce voltages to induce more winding currentmore winding current

Chopper delivers more Chopper delivers more torque at higher speedstorque at higher speedsELECTROMATE


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NPM Half Stepping A Stepper MotorHalf Stepping A Stepper Motor

Easiest way to accomplish half stepping Easiest way to accomplish half stepping is by using 1is by using 1--2 phase excitation2 phase excitation

Divides a stepperDivides a stepper’’s full step angle by s full step angle by two 7.5two 7.5°°/2 = 3.25/2 = 3.25°° per half stepper half step

30% loss of torque depending on step 30% loss of torque depending on step rate when compared to full steprate when compared to full step

Winding is not energized during each Winding is not energized during each alternating half stepalternating half step



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NPM

NN

SS

NN

SS

●●

PHASE APHASE A


PHASE APHASE A

STEP 1STEP 1

SS

NN

SS

NN●●

PHASE APHASE A


PHASE APHASE A

STEP 2STEP 2

NNSS

SS

NN●●

PHASE APHASE A


PHASE APHASE A

STEP 4STEP 4

NN SSNNSS ●●

PHASE APHASE A


PHASE APHASE A

STEP 3STEP 3

Half SteppingHalf Stepping SequenceSequence

Two PhaseTwo Phase Stepper MotorStepper Motor

NN SS

SS

NN



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NPM Microstepping A Stepper MotorMicrostepping A Stepper Motor

Full step can be broken into as many as Full step can be broken into as many as 512 parts512 parts

Current is limited through each winding. Current is limited through each winding.

Unequal pull on the magnet means it Unequal pull on the magnet means it moves toward the weaker winding moves toward the weaker winding

Torque falls rapidly as speed increasesTorque falls rapidly as speed increases

Steps are not constant for positioningSteps are not constant for positioning

Microstepping should only be used for Microstepping should only be used for smooth movement.smooth movement. ELECTROMATE


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NPM Combined Sequencer & TranslatorCombined Sequencer & Translator



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