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Basics of an ac drive - with motor basics

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- 1. 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
- 2. 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.
- 3. Varying the Speed of an AC Motor 1800 1800 = 60 x 120(rpm) (rpm) 4 900 900 = 30 x 120(rpm) (rpm) 4 30 Hz 60 Hz
- 4. AC Motor ReviewIn an AC motor, Torque Varies by: E 2T = K x ( ) x I Line F Where: K is a constant E is applied voltage F is input frequency I Line is motor current
- 5. AC Motor Review Torque/Current RelationshipWhat you really need to know…... • Current is roughly proportional to load torque • The higher the load torque the higher the current
- 6. AC Motor ReviewHorsepower of an AC motor can be determined by: HP = Torque x Speed 5252 Where: Torque is in lb-ft Speed is in RPM 5252 is a constant
- 7. Motor nameplate Horsepower is achieved at Base RPM: HP = Torque * Speed / 5252 Constant Torque Constant Horsepower Range Range PM R Note that motor na horsepow meplate er is only achieved at and ab Horsepower base spe ov ed , NOT B e EFORE. d ee Sp10 u e 0% e rq asTo B
- 8. Operation Above Base Speed HP
- 9. AC Motor Review IMPEDANCEIMPEDANCE: Resistance of AC Current flowingthrough the windings of an AC Motor NOTE: Impedance decreases as frequency decreases
- 10. Volts/Hertz Relationship I = Current V = Voltage I=V Z = Impedance ZTo reduce motor speed effectively:• Maintain constant relationship between current & torque• A constant relationship between voltage and frequency must be maintained
- 11. Volt/Hertz Relationship460 V The AC variable speed drive controls voltage & frequency230 V simultaneously to maintain constant volts-per-hertz relationship keeping current flow constant. 30 Hz 60 Hz
- 12. AC Drive Rectifier DC Bus InverterAC Power Supply M V V V V T T T•Rectifier • Inverter - Converts AC line voltage to Pulsating DC voltage - Changes fixed DC to adjustable AC - Alters the Frequency of PWM waveform • Intermediate Circuit (DC BUS) - Filters the pulsating DC to fixed DC voltage
- 13. Sine Weighted PWM Bus Voltage Level
- 14. Sine Weighted PWM
- 15. PWM WAVEFORM VLL @ Drive 500 Volts / Div.+ DC Bus 1- DC Bus 3 Phase Current 10 Amps / Div. M2.00µs Ch1 1.18V PWM waveform is a series of repetitive voltage pulses
- 16. Drive and Motor Compatibility Voltage Wave VLL @ Drive @Drive Output 500 Volts / Div.PotentiallyDamagingVoltagePeaks VLL @ Motor 500 Volts / Div. Voltage Wave @ Motor Conduit Box
- 17. How to Specify -- NEMA Standards MG1-1993, Part 31.40.4.2 Maximum of 1600 Volt Peaks VpeakVoltage Steady-state voltage 100% 90% ∆ V dV ∆ V = dt ∆ t 10% ∆ t Time Rise time Minimum Rise Time of .1 Microseconds
- 18. GV3000/SEV/Hz OperationOutput 460Voltage Ratio @ 460VAC = 7.67 V/Hz 230 115 Hz 0 15 30 60 90 Output Base Frequency Frequency At Base RPM or 60Hz, the Motor sees line input voltage
- 19. GV3000/SEV/Hz OperationOutput 460Voltage Ratio @ 460VAC = 7.67 V/Hz 230 115 Hz 0 15 30 60 90 Output Base Frequency FrequencyAt 25% of Base RPM or 15 Hz, Voltage & Frequency is 25%
- 20. VECTOR DRIVE Magnetizing Current 25.0 (8.5 Amps) Amps Full Load Torque - Producing Current (23.5 Amps)Vector calculates Torque-Producing Current byknowing actual amps and magnetizing current.
- 21. GV3000/SEVector Control - Torque can be produced, as well as regulated even at “0” RPM Motor Current is the VECTOR SUM of Magnetizing Motor Current is the VECTOR SUM of Magnetizing & Torque Current, & Torque Current, 100% this is where the term VECTOR DRIVE is derived this is where the term VECTOR DRIVE is derived Torque Current Motor Torque Current Current Motor 10% Current 90° 90° Magnetizing Current Magnetizing CurrentMotor Current is the Vector Sum of Torque & Magnetizing
- 22. GV3000/SEFlux Vector Drive - simple diagram reviewA Vector Drive always regulates current “LEM” Current Sensors L1 L2 Motor L3 E Micro PEncoder feedback provides rotor speed & position information for calculations
- 23. GV3000/SESensorless Vector Control - simple diagram reviewSVC estimates rotor speed & position to the stator field “LEM” Current Sensors L1 L2 Motor L3 Micro P ( FVC + Speed Estimator )A “Speed Estimator” calculates rotor speed & position to maintain 90° to the field
- 24. Sensorless Vector Flux Vector 150% Overload 150% Overload Operation to 0 RPM Operation @ 0 RPM 120:1 Speed Range 1000:1 Speed Range Speed Regulation Speed Regulation 40:1, 0.5% Steady State 100:1, 0.01% Steady State 20:1, 1.0% Dynamic 100:1, 0.5% Dynamic Dynamic Response Dynamic Response 100+ radian Speed Loop 100+ radian Speed Loop 1000 radian Torque Loop 1000 radian Torque Loop Tunable Speed PI gains Tunable Speed & Torque PI gains
- 25. INVERTER DUTY MOTORSNEMA Design ‘B” Motor w/ 3% Slip - Across the Line Start BDT 200% Operating LRT Region on AC PUT Drives 100% FLT Slip Base RPM AC Drives regulate Motor Speed based on designed slip
- 26. INVERTER DUTY MOTORS Blowers may be added to Blowers may be added to motors to allow operation at low motors to allow operation at low speed including “0” RPM with speed including “0” RPM with 100% Torque continuous 100% Torque continuous Some motor frames are sized so that Some motor frames are sized so that just the surface area is suitable to just the surface area is suitable todissipate motor heat w/o the need of adissipate motor heat w/o the need of a fan or blower fan or blower
- 27. GV3000/SE with “Inverter & Vector Duty” AC MotorsVXS Motors Based on Reliance XEX Motor Designs TENV, TEFC-XT and TEBC Enclosures Ideal for; Positive Displacement Pumps and Blowers Extruders and Mixers Steel and Converting Process lines Standard Features; Encoder Mounting Provisions Motor Shaft Tapped for Stub @ ODE Accessory Face @ ODE Motor Winding Thermostats, 1/Phase 10:1 to 1000:1 CT speed ranges w/o derating
- 28. GV3000/SE with “Inverter & Vector Duty” AC MotorsRPM-AC Motors Laminated Steel, DC-style construction DPFV, TENV, & TEBC enclosures Ideal for; Extruder applications Web processing & mill applications Retrofitting existing DC Drive & Motor systems Standard Features; High torque to inertia ratios Encoder Mounting Provisions Motor Winding Thermostats, 1/Phase Infinite CT speed range, 0 RPM continuous CHp Range of 2:1 on TENV & TEBC Frames Base Speeds from 650 RPM to 3600 RPM
- 29. Speed RangeSpeed Range - Designed operating range of an inverter duty motorExample1800 rpm motor10:1 Speed Range = 180 -1800 (rpm)
- 30. CONSTANT TORQUE REGIONSpeed / Torque Curve of an AC Drive & Inverter Duty Motor 100 Torque 90 % 80 Torque T 70 O 60 R 50 Q 40 Acceptable Region U 30 for Continuous Operation E 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 HZ Inverter Duty Motors operate at 1/4th Base RPM
- 31. CONSTANT HP REGIONSpeed / Torque Curve of an AC Drive & Inverter Duty Motor 100 Torque 90% 80 TorqueT 70O 60 Torque aboveR 50 base RPM =Q 40 100%U 30 % Base RPME 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 HZ CHp Operation above Base RPM is typically limited to 150%
- 32. CONSTANT TORQUE REGIONSpeed / Torque Curve of a Vector Drive & Vector Duty Motor 100 Torque 90 % 80 Torque T 70 O 60 R 50 Q 40 Acceptable Region U 30 for Continuous Operation E 20 10 0 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 HZ Vector Duty Motors operate at “0” RPM w/ 100% Torque Cont.
- 33. CONSTANT HP REGIONSpeed / Torque Curve of a Vector Drive & Vector Duty Motor 100 Special motor & drive Special motor & drive 90 designs can allow operation designs can allow operation% 80 up to 8 * Base RPM up to 8 * Base RPMT 70O 60 TorqueR 50 TorqueQ 40 Vector Duty Motors may haveU 30 CHP Ranges ofE 20 2 * Base Speed or more 10 depending on their design 0 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120 HZ Some Vector Duty Motors can provide CHp ( 2 * Base RPM )
- 34. Drive Terminology V/Hz Restart DC Boost Preset Accel / Decel Jog Frequency Current Limit Voltage Analog / Digital HP Power Factor Speed Harmonics Skip & Bandwith Ride - Thru Braking Speed Range DB Speed Regulation Regen Frequency Regulation Injection Cogging Coast Efficiency Ramp
- 35. Accel/Decel Acceleration Rate - Deceleration Rate Rate of change of motor speed. 100 % Example:Frequency 0 Speed - 1750 rpm 30 seconds 30 sec TIME
- 36. Full Voltage Bypass Drive Bypass Branch Disconnect Fusing Switch GV3000/SE M InputDisconnect Switch Bypass Option
- 37. Speed RegulationHow Much Will the Speed ChangeBetween No Load and Full Load? Expressed as a Percentage
- 38. Speed Regulation
- 39. DC Voltage Boost
- 40. Voltage BoostVoltage Boost over prolonged operating periods may result inoverheating of the motor’s insulation system and result inpremature failure. CAUTION: Motor Insulation Life is decreased by 50% for every 10°C above the insulation’s temperature capacity Unable to perform like DC, the industry looks to Vector Control
- 41. 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
- 42. Skip Bandwith605040 Command Freq. Output Freq30 Skip Band Skip Freq20100 0 1 2 3 4 5 6 7 8 9 10
- 43. AC Drive InputsAnalog Inputs: Digital Inputs:• 0-10 VDC • Start• ± 10 VDC • Stop• 4-20 mA • Reset • Forward/Reverse • Run/Jog • Preset Speeds
- 44. GV3000/SEHigh Bus Avoidance ( SVC & FVC ) For Trip Free Deceleration if low to medium inertia loads SPEED TIME Trip Free Deceleration when enabled
- 45. Snubber/Dynamic Braking Rectifier DC Bus InverterAC Power Supply M• Snubber/Dynamic Braking - Addition of Snubber Resitor Kit 7th IGBT - Dissipates excess energy to regulate braking Braking Resistor - Regulator monitors DC bus voltage - Signal sent to 7th IGBT - Handles short term regenerative loads - Less expensive than AC line regeneratiion braking
- 46. AC Regenerative BrakingAC Power Supply AC Line Drive 1 Drive 2 Drive 2 Regeneration Module• Severe Regenerative Braking - Drives powered through DC bus instead - Addition of AC Line Regeneration Module - Monitors DC bus voltage of through the Rectifier bridge - Sends Excess voltage back to AC line - Share regenerative energy between - Handles long term regenerative loads motoring and regenerating drives - Run Multiple Drives off 1 Module - Send energy back to AC Line instead of dissipating as heat
- 47. Auto - RestartHow will the drive react after being shut down by a fault condition? Will the drive resumeRunning after the Fault condition is Cleared? (Sometime restricted to certain Faults)
- 48. Preset SpeedsA Pre-Programmed Command Frequency That can be activated via Mode Select or Input Device
- 49. 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.
- 50. Power Loss Ride-Through The Ability of a Controller to sustain itself through a loss ofInput Line Voltage for a specific period of time.
- 51. Operating Range ForVariable Frequency AC Drives

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