* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download V/F control - ResearchGate
Electrical substation wikipedia , lookup
Power engineering wikipedia , lookup
Current source wikipedia , lookup
History of electric power transmission wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Solar micro-inverter wikipedia , lookup
Brushless DC electric motor wikipedia , lookup
Schmitt trigger wikipedia , lookup
Three-phase electric power wikipedia , lookup
Stray voltage wikipedia , lookup
Integrating ADC wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Electric motor wikipedia , lookup
Distribution management system wikipedia , lookup
Brushed DC electric motor wikipedia , lookup
Voltage regulator wikipedia , lookup
Opto-isolator wikipedia , lookup
Alternating current wikipedia , lookup
Buck converter wikipedia , lookup
Power inverter wikipedia , lookup
Mains electricity wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Stepper motor wikipedia , lookup
Voltage optimisation wikipedia , lookup
Electric machine wikipedia , lookup
Speed control of squirrel cage induction machine using V/F control Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki 1 Agenda Introduction Applications of AC drives Types of Methods to control the speed of Induction machine V/F control Power Converters Simulation Model Simulation Results Conclusion Reference 2 Introduction An electric drive system consisting of electric motor, its power controller and energy transmitting shaft consisting of load Types of Drive system (1)DC Drive (2)AC Drive AC Drives are mostly used in Industry. 3 Advantages and disadvantages of AC Drives compare to DC Drives Advantages of ac drives 1. For the same rating, ac motors are lighter in weight as compared to dc motors. 2. AC motors require low maintenance. 3. AC motors are less expensive. 4. AC motors can work in dangerous areas like chemical, petrochemical etc. Disadvantage of ac drives 1.Power converters for the control of ac motors are more complex. 2.Power converter for ac drives are more expensive. 3.Power converters for ac drives generate harmonics in the supply system and load circuit. 4 Industrial applications Induction motors with squirrel cage rotors are the workhorse of industry because of their low cost and rugged construction. When Squirrel cage induction machine is operated directly from the line voltages(60 Hz/50 Hz essentially constant voltage) an Induction motor is operated at constant speed. However in the industry we required to vary the speed of an Induction motor. This can be done by Induction motor drives. Main application of Induction Motor drives: Fans, Compressor, Pumps, blowers, machine tools like lathe, drilling machine, lifts, conveyer belts etc. 5 Methods of Speed Control of Induction motors (1) Stator voltage Control (2) Stator Frequency Control (3) Stator Current Control (4) V/F Control (5) Slip power recovery Control ( Wound Rotor Induction Machine) 6 Curve of the behavior of the Induction Machine • During start up. Normally draws up to seven times the rated current. • Normally delivers approximately 1.5 the rated torque, when starting • When operating at base speed if the load is increased, the motor will start slowing down and the slip will increase. •But if the load is increased beyond the Break down torque, the machine wont be able to recover. 7 V/Hz Theory Background The induction motor draws the rated current and delivers the rated torque at the base speed. As mentioned before the motor can take up to 2.5 load increase, with 20% drop in the speed. 8 Description of the principle Assume the voltage applied to the Motor is AC, and the voltage drop across the Armature resistance very small. Then at the steady state we get: (Voltage applied at the stator, and Flux) Since the V/f relation keeps constant, then the flux remains constant and the torque is independent of the supplied frequency. 9 Description of the Principle Since the flux is maintained constant, the toque developed depends only on the slip speed. Huge starting torque can be obtained without heating-up the machine 10 V/Hz Open Loop Torque Synchronous frequency 11 V/Hz control Closed loop 12 Three Phase Full Bride Uncontrolled Rectifier 13 DC-DC Boost Converter 14 DC-DC Boost Converter 15 3 Phase PWM Inverter 16 Block Diagram of Simulation Model 17 Simulation Model 18 Uncontrolled Rectifier and DC-DC Boost Converter Simulation Model 19 3 phase inverter with Squirrel Cage Induction Motor 20 Simulation Results Input Voltage for 3 phase uncontrolled Rectifier Voltage input to rectifier Vin A Vin B Vin C 300 200 Input Voltage to rectifier(V) 100 0 -100 -200 -300 -400 4.14 4.145 4.15 4.155 4.16 4.165 4.17 4.175 Time(s) 21 Simulation Results Output Voltage of three phase uncontrolled rectifier Vin A Vin B Vin C Rectified Output voltage 300 200 Output Voltage of Rectifier(V) 100 0 -100 -200 -300 0.08 0.1 0.12 0.14 0.16 Time(s) 0.18 0.2 0.22 0.24 22 Simulation Results Output Voltage of DC/DC Boost converter Output Voltage of DC DC Converter 400 Vdc out 350 Output Voltage of DC DC Converter(V) 300 250 200 150 100 50 0 0 2 4 6 8 10 Time(s) 12 14 16 18 20 23 Simulation Results Voltage Output inverter phase Voltage Voltage Voltage Output inverter phase Output inverter phase C(V)) B(V)) A(V)) Output inverter(V)) Output Voltage of 3 Phase PWM inverter before filter Output Voltage of Inverter before filter 500 Vout inv A Vout inv B Vout inv C 0 -500 0 0.05 0.1 0.15 0.2 0.25 Time(s) 0.3 0.35 0.4 0.45 0.5 0 0.05 0.1 0.15 0.2 0.25 Time(s) 0.3 0.35 0.4 0.45 0.5 0 0.05 0.1 0.15 0.2 0.25 Time(s) 0.3 0.35 0.4 0.45 0.5 0 0.05 0.1 0.15 0.2 0.25 Time(s) 0.3 0.35 0.4 0.45 0.5 500 0 -500 500 0 -500 500 0 -500 24 Simulation Results Output Voltage of Inverter after filter ( Controlled Input voltage given to Induction motor) Output Voltage of Inverter after filter(input Voltage to Machine) 250 Output Voltage of Inverter after filter(input Voltage to Machine) Vin m A Vin m B Vin m C 200 Vin m A Vin m B Vin m C 200 150 150 100 100 Voltage Input to Machine(V) Voltage Input to Machine(V) 50 50 0 -50 0 -50 -100 -100 -150 -150 -200 -200 -250 0 2 4 6 8 10 Time(s) 12 14 16 18 20 3.68 3.7 3.72 3.74 3.76 3.78 Time(s) 3.8 3.82 3.84 3.86 3.88 25 Simulation Results Stator Current Stator Current 10 Istator A Istator B Istator C 8 6 4 Stator Current(A) 2 0 -2 -4 -6 -8 -10 3.55 3.6 3.65 3.7 3.75 3.8 3.85 3.9 Time(s) 26 Simulation Results Rotor Reference speed and Actual Speed Here the reference speed is 1000 rpm= 104.72 rad/sec Rotor Speed 120 Reference Speed Actual Speed 100 Rotor Speed (rad/sec) 80 60 40 20 0 -20 0 2 4 6 8 10 Time(s) 12 14 16 18 20 27 Simulation Results Without Filter after the PWM inverter , rotor speed is fluctuating 28 Simulation Results Rotor Reference speed and Actual Speed Rotor Speed 100 Reference Speed Actual Speed 90 80 70 Reference speed is 600rpm= 62.83 rad/sec Rotor Speed (rad/sec) 60 50 40 30 20 10 0 -10 0 2 4 6 Rotor Speed 8 10 12 14 Time(s) 140 Reference Speed Actual Speed 120 100 Rotor Speed (rad/sec) 80 Reference speed is 1300 rpm=136.14 rad/sec 60 40 20 0 -20 0 2 4 6 8 180 10 Time(s) Rotor Speed 12 14 16 18 20 Reference Speed Actual Speed 160 140 120 100 Rotor Speed (rad/sec) Reference speed is 1500rpm= 157.08 rad/sec 80 60 40 20 0 -20 0 2 4 6 8 10 Time(s) 12 14 16 29 18 20 Rotor Reference speed and Actual Speed Reference Speed is changed from 104.71 rad/sec to 92.24 rad/sec Rotor Speed 120 Reference Speed Actual Speed 100 Rotor Speed (rad/sec) 80 60 40 20 0 -20 0 2 4 6 8 10 Time(s) 12 14 16 18 20 30 Conclusion In Case of Squirrel cage induction motor the slip cannot be increase above certain limit, the operating speed range is very less. By applying the V/F control we can get the large operating range by keeping V/F ratio constant. 31 32 Reference [1] Modern Power Electronics and AC drives by Bose, Bimal K. [2] POWER ELECTRONICS Converters, Applications and Design by Ned Mohan [3] Power electronics Lecture Notes by Prof. Nasiri [4] Lecture Notes by Dr. Omar [5] AC Induction Motor Control using Constant V/Hz Principe and Space Vector PWM Technique with TMS320 C240 [6] Speed Control of 3-Phase Induction Motor Using PIC18 Microcontrollers 33