Review of How Motor WorksMotor converts Electrical Energy to Rotating Mechanical EnergyCoils placement in motor creates rotating, magnetic field in statorRotating magnetic field cuts rotor bar and induces current in rotorRotor current creates magnetic field on rotorAttraction of rotor to stator creates torque and, hence, horsepower

AC Motor ReviewIn an AC Motor, speed varies by:

Motor Speed (rpm) = 120 x Frequency - Slip

# of Poles

Since you can not change the number of poles in an AC motor,the frequency is changed to vary the speed.

Varying the Speed of an AC Motor60 Hz30 Hz1800(rpm)900(rpm)1800 = 60 x 120(rpm) 4900 = 30 x 120(rpm) 4

AC Motor Review

AC Motor ReviewTorque/Current RelationshipWhat you really need to know... Current is roughly proportional to load torque

The higher the load torque the higher the current

AC Motor ReviewHorsepower of an AC motor can be determined by:HP = Torque x Speed 5252Where:Torque is in lb-ftSpeed is in RPM5252 is a constant

Motor nameplate Horsepower is achieved at Base RPM:HP = Torque * Speed / 5252Constant Torque RangeConstant Horsepower Range

Operation Above Base SpeedHP

AC Motor ReviewIMPEDANCEIMPEDANCE: Resistance of AC Current flowing through the windings of an AC MotorNOTE: Impedance decreases as frequency decreases

Volts/Hertz RelationshipI = CurrentV = VoltageZ = ImpedanceI = V ZTo reduce motor speed effectively: Maintain constant relationship between current & torque A constant relationship between voltage and frequency must be maintained

Volt/Hertz Relationship60 Hz30 Hz230 V460 VThe AC variable speed drive controls voltage & frequencysimultaneously to maintain constant volts-per-hertz relationshipkeeping current flow constant.

AC DriveDC BusRectifier - Converts AC line voltage to Pulsating DC voltage Inverter - Changes fixed DC to adjustable AC - Alters the Frequency of PWM waveform Intermediate Circuit (DC BUS) - Filters the pulsating DC to fixed DC voltageAC Power SupplyRectifierInverterM

Sine Weighted PWMBus Voltage Level

Sine Weighted PWM

PWM WAVEFORMPWM waveform is a series of repetitive voltage pulses

Drive and Motor CompatibilityVoltage Wave @Drive OutputVoltage Wave @ Motor Conduit BoxPotentially Damaging Voltage Peaks

How to Specify -- NEMA StandardsMG1-1993, Part 31.40.4.2Maximum of 1600 Volt Peaks Minimum Rise Time of .1 Microseconds

GV3000/SEV/Hz OperationAt Base RPM or 60Hz, the Motor sees line input voltage

GV3000/SEV/Hz Operation At 25% of Base RPM or 15 Hz, Voltage & Frequency is 25%

VECTOR DRIVEVector calculates Torque-Producing Current by knowing actual amps and magnetizing current.

GV3000/SEVector Control - Torque can be produced, as well as regulated even at 0 RPMMotor Current is the Vector Sum of Torque & MagnetizingMotor Current is the VECTOR SUM of Magnetizing & Torque Current,this is where the term VECTOR DRIVE is derived

GV3000/SEFlux Vector Drive - simple diagram reviewA Vector Drive always regulates currentEncoder feedback provides rotor speed & position information for calculations LEMCurrent Sensors

GV3000/SESensorless Vector Control - simple diagram reviewSVC estimates rotor speed & position to the stator field A Speed Estimator calculates rotor speed & position to maintain 90 to the fieldL1L2L3 MotorMicro P( FVC + Speed Estimator )LEMCurrent Sensors

150% OverloadOperation to 0 RPM120:1 Speed RangeSpeed Regulation40:1, 0.5% Steady State20:1, 1.0% DynamicDynamic Response100+ radian Speed Loop1000 radian Torque LoopTunable Speed PI gains150% OverloadOperation @ 0 RPM1000:1 Speed RangeSpeed Regulation100:1, 0.01% Steady State100:1, 0.5% DynamicDynamic Response100+ radian Speed Loop1000 radian Torque LoopTunable Speed & Torque PI gainsSensorless VectorFlux Vector

INVERTER DUTY MOTORSAC Drives regulate Motor Speed based on designed slipNEMA Design B Motor w/ 3% Slip - Across the Line Start200%BDTFLT100%Base RPM

PUTLRT

INVERTER DUTY MOTORS

GV3000/SE withInverter & Vector Duty AC MotorsVXS MotorsBased on Reliance XEX Motor DesignsTENV, TEFC-XT and TEBC EnclosuresIdeal for;Positive Displacement Pumps and BlowersExtruders and MixersSteel and Converting Process linesStandard Features;Encoder Mounting ProvisionsMotor Shaft Tapped for Stub @ ODE Accessory Face @ ODEMotor Winding Thermostats, 1/Phase10:1 to 1000:1 CT speed ranges w/o derating

GV3000/SE withInverter & Vector Duty AC MotorsRPM-AC MotorsLaminated Steel, DC-style constructionDPFV, TENV, & TEBC enclosuresIdeal for;Extruder applicationsWeb processing & mill applicationsRetrofitting existing DC Drive & Motor systemsStandard Features;High torque to inertia ratiosEncoder Mounting ProvisionsMotor Winding Thermostats, 1/PhaseInfinite CT speed range, 0 RPM continuousCHp Range of 2:1 on TENV & TEBC FramesBase Speeds from 650 RPM to 3600 RPM

Speed RangeSpeed Range - Designed operating range of an inverter duty motor

Example1800 rpm motor10:1 Speed Range = 180 -1800 (rpm)

CONSTANT TORQUE REGIONInverter Duty Motors operate at 1/4th Base RPMSpeed / Torque Curve of an AC Drive & Inverter Duty Motor

CONSTANT HP REGIONCHp Operation above Base RPM is typically limited to 150%Speed / Torque Curve of an AC Drive & Inverter Duty Motor% TORQUE0102030405060708090100061218243036424854606672788490TorqueTorqueHZ

CONSTANT TORQUE REGIONVector Duty Motors operate at 0 RPM w/ 100% Torque Cont.Speed / Torque Curve of a Vector Drive & Vector Duty Motor

CONSTANT HP REGIONSome Vector Duty Motors can provide CHp ( 2 * Base RPM )Speed / Torque Curve of a Vector Drive & Vector Duty MotorSpecial motor & drive designs can allow operation up to 8 * Base RPM

Drive TerminologyV/HzDC BoostAccel / DecelFrequencyVoltageHPSpeedSkip & BandwithBrakingDBRegenInjectionCoastRampRestartPresetJogCurrent LimitAnalog / DigitalPower FactorHarmonicsRide - ThruSpeed RangeSpeed RegulationFrequency RegulationCoggingEfficiency

Accel/DecelAcceleration Rate - Deceleration Rate

Rate of change of motor speed.

Example:0 Speed - 1750 rpm 30 seconds

Full Voltage BypassGV3000/SEMInputDisconnectSwitchDriveBranchFusingBypassDisconnectSwitchBypassOption

Speed RegulationHow Much Will the Speed Change

Between No Load and Full Load?

Expressed as a Percentage

Speed Regulation

DC Voltage Boost

Voltage BoostVoltage Boost over prolonged operating periods may result in overheating of the motors insulation system and result in premature failure.Unable to perform like DC, the industry looks to Vector ControlCAUTION: Motor Insulation Life is decreased by 50% for every 10C above the insulations temperature capacity

Critical Frequency An Output Frequency of a Controller that

Produces a Load Speed at Which Severe

Vibration Occurs.

A Frequency at which Continuous Operation

is Undesirable

Skip Bandwith

AC Drive InputsAnalog Inputs: 0-10 VDC 10 VDC 4-20 mADigital Inputs: Start Stop Reset Forward/Reverse Run/Jog Preset Speeds

GV3000/SEFor Trip Free Deceleration if low to medium inertia loadsTrip Free Deceleration when enabledHigh Bus Avoidance ( SVC & FVC )

Snubber/Dynamic BrakingDC BusAC Power SupplyRectifierInverterMBraking Resistor7th IGBT Snubber/Dynamic Braking - Addition of Snubber Resitor Kit - Dissipates excess energy to regulate braking - Regulator monitors DC bus voltage - Signal sent to 7th IGBT - Handles short term regenerative loads - Less expensive than AC line regeneratiion braking

AC Regenerative BrakingAC Power Supply Severe Regenerative Braking - Addition of AC Line Regeneration Module - Monitors DC bus voltage - Sends Excess voltage back to AC line - Handles long term regenerative loadsAC Line Regeneration Module - Run Multiple Drives off 1 Module - Drives powered through DC bus instead of through the Rectifier bridge - Share regenerative energy between motoring and regenerating drives - Send energy back to AC Line instead of dissipating as heat

Auto - RestartHow will the drive react after being shut down

by a fault condition? Will the drive resume

Running after the Fault condition is Cleared?

(Sometime restricted to certain Faults)

Preset SpeedsA Pre-Programmed Command Frequency

That can be activated via Mode

Select or Input Device

Current Limit

The ability of a drive to react to the increased current caused by momentarilyincreasing the load on the motor (Shock Loading) without tripping the drive on Overcurrent.

Power Loss Ride-Through The Ability of a Controller to

sustain itself through a loss of

Input Line Voltage for a specific

period of time.

Operating Range ForVariable Frequency AC Drives

Torque in an AC motor is calculated using a constant, the volts over the frequency squared, and the line current.

If you are running at a fixed speed and K is a constant, the Torque is directly proportional to the motor current. As it increases and decreases so does the torque.

Sure! if we maintain voltage and increase resistance, the current will begin to drop. We are now in the constant voltage mode of operation, and Torque begins to fall off.

The Sine weighted PWM voltage output to the motor looks like this. The frequency of the switch from positive to negative is determined by the drive based on the speed reference input, and the RMS or Average voltage value for that frequency is determined by the number and width of the pulses. If I vary or "Modulate" the pulse width, I vary the RMS Voltage to the motor.

That voltage creates a current waveform in the motor that is very nearly a sine wave; certainly much closer to a true sine wave than the other technologies used in AC Drives. Here are the PWM waveforms. So by modulating or changing the Width of the voltage pulses and the frequency that those pulses create we create a very close approximation of a sinusoidal current waveform. The near sinusoidal nature of the current accomplishes two of our four goals; minimizing the low order harmonics you can see that the spikes are much smaller than in other technologies and maximizing the transfer of power in the fundamental frequency.

33Scope traces from a 10 HP, 460 VAC VFD with 500 feet of cable between the VFD and the motor. The top wave shows the frequency at the drive output terminals. The bottom wave is the same wave at the motor terminals. An effect, called reflected wave, has raised the peak voltage at the motor terminals.At a minimum, variable-speed AC moors should meet NEMA MG1 Part 31.40.4.2 standards. That standard is depicted here.

They should also have a minimum CIV rating of 1,600 V at rated operating temperature for 460 VAC applications and should have a higher voltage rating for 575 VAC applications.

Always follow the lead length recommendations of the VFD manufacturer. Most have done extended testing to understand the reflected wave voltage amplitudes and dv/dt created by their products.

Use reactors and filters when the distance between the drive and the motor exceeds the manufacturers recommendations.

Use power-matched motor/drive packages that have been tested for compatibility in a wide range of operating conditions.Optional Motor review slide

Optional Motor review slideSpeed Regulation, as a Percentage, is how much the speed will change between no load (Minimal slip) and Full Load (Maximum Slip).

Here's a curve for a standard Induction motor. 3% drop in speed. But a standard DC Drive typically has a 12% speed Regulation, and, out of the box, a motion control drive provides .1% speed regulation. Why the difference?

The difference is that most DC drives and all Motion Control Drives are what's known as closed loop. That means that some sort of feedback device attached to the motor feed speed information back to the drive for use in correcting any speed discrepancies. Open loop, like most AC Drives, means no such feedback exists, and the drive assumes that what it told the motor to do is actually being done.

That's where DC Boost comes in. In order to drop enough voltage across the inductance, we raise or boost the output voltage above what it would be normally, until there is enough voltage across the inductance to provide the necessary torque to turn the motor or "Break" the motor away. Once that voltage boost reaches the level that it would have been on the standard curve, the boost is turned off and operation proceeds as normal. We accomplish DC Boost by widening the pulses in the PWM waveform, creating a higher average voltage, and therefore more current.

Now that we understand the technology of AC drives, we need to apply what we know to the characteristics we already know about the AC Motor. Only then can we know how the two will react together. Here is our standard speed torque curve for our NEMA B design motor. An AC Drive has a fixed Maximum Continuous Current limit which we have shown here as a dotted line representing 100% of drive current. In addition, most drives have an intermittent ability to supply current up to some additional level. We have chose the 150% level found in drives like the BUl 1336. Since the drive will be limiting the current available to the motor, we will no longer see the entire speed torque curve. We will not be able to get full breakdown torque from the motor and will not see 200% starting torque as we did across the line. Remember that 200% required 600% current. We are now limited to 150%. What we create then, is an operating range on the torque curve for a motor use with a drive. the area you see here is for full voltage at rated frequency. A motor controlled by an AC Drive will always operate somewhere in this range.