Electronic starters and variable speed drives ATV71 the motor control

Training module The motor control Dominique GENDRON Franỗois MALRAIT 12/28/15 Bertrand Guarinos STIE ATV71 M3 commande moteur R2 EN Summary Introduction ATV71 The ATV71 includes several motor control laws These different laws allow the drive to be adapted to a great variety of induction motors and machines This module describes these command law, their application, as well as their associated functions Summary Summary ATV71 I The motor control laws II.Motor control menu III Protection against motor o ver v oltage IV.Specific applications Summary The motor control I ATV71 The motor control laws • • • • • The basics of flux vector control The voltage flux vector control law SVC U The current flux vector control law SVC I The volts/Hertz law (U/f) The synchronous motor law II.Motor control menu III Protection against motor over v oltage IV Specific applications Summary The motor control laws ATV71 Flux vector control basics Summary Flux vector control basics ATV71 • The control of an asynchronous motor is made more difficult by the fact that the electrical parameters (current, voltage, flux) are alternating • Furthermore, flux and torque are dependant upon current • The principal of flux vector control consists in transforming the machine equations in such a fashion so as to:: – use variables as though the are continuous and no longer alternating, – simplify the equations in order to decouple the flux and torque variables Flux φ r = K1 Id Torque C = K2 φ s Iq • Flux is proportional to the Id component of current • If the flux is constant, the torque is proportional to the Iq component of current Summary Flux vector control basics • • • ATV71 Vector control allows the controller to separate the torque producing current and the flux producing current This is analogous to a DC motor with separate excitation Flux is maintained constant and set at a point to obtain constant torque over the entire speed range Asynchronous Motor DC Motor Φr Φr Φs I inductive I induced Φs Id Flux Torque Iq • • The vector control has a speed estimation function that allows the full time correction of torque and flux Thus the performance is much better, for low speed torque, dynamic response, and speed precision compared to a scalar volts/Hertz law Summary Flux vector control basics ATV71  Comparison of U/F and Vector control Flux Vector Control U/F Law Automatic Compensation (Rs and slip) Manual Compensation (U0 voltage at origin) C/Cn C/Cn 200 % 100% F hz FrS F hz 10 FrS Summary Flux vector control basics ATV71  Torque/current relationship • The link between current/torque is dependent upon the type and size of the motor as well as the optimization of the command law Example for a motor with Id = 50% of In Torque 220% In Typical Values 162% 100% 0% 1.5 In In 0.5 In 50% "Id" = Flux Summary The motor control laws ATV71 Voltage vector control law SVC U Summary LR filters ATV71  Qualification curves Summary Sinusoidal filters ATV71  Principal • There are differential and common mode LC filters • The voltage on the output is nearly sinusoidal • They are available up to 75kW  Application • • • Cable length up to 300 meters Very great length of cable Best for EMC Summary Sinusoidal filters ATV71 Performance • Cable length of up to 300 meters • Practically eliminated high frequency earth leakage currents • Suppresses overvoltages • Very good for radiated EMC • Can avoid the use of shielded cable • High cost Summary Sinusoidal filters ATV71  Qualification curves Summary Summary of overvoltage protection Cable small drives large drives 20 m Drive Software Drive Software Drive Software Drive Software 50 m 100m dV/dt Filter ATV71 150m Sine Filter 300m Sine Filter dV/dt Filter dV/dt Filter Sine Filter Sine Filter Shielded Not shielded Summary The motor control I ATV71 The motor control laws II Motor control menu III Protection against motor over v oltage IV Specific applications • Motors in parallel • Single phase • High speed motors Summary Motors in parallel • • • • ATV71 The nominal drive current must be greater or equal to the sum of the currents of the motors to be controlled Each motor requires its own external thermal protection If the motors are identical try the voltage vector control law in open loop by entering an equivalent motor nameplate information and doing and auto-tune (TUN) If the motors are of different powers, the drive settings are not optimized for the lowest power motors L1 L2 L3 Summary Motors in parallel • • • • • ATV71 If there are many motors or the sizes are different use the Volts/Hertz law If motors are being switched on the drive output (variable load) use the Volts/Hertz law If the number of motors in parallel is > 3, it is recommended to install an output filter between the drive and the motors and/or reduce the chopping frequency The cable length to be considered for choosing an output filter is the sum of all the cable lengths (ex L1+L2+3L3) Minimize the cable length (drive as close as possible to the motors) L1 L2 L3 Summary Motor switching • Switching can be done whether the drive is running or not • During a switch on the fly (drive running), the motor is controlled and accelerated up to the reference speed without a shock (catch on the fly) To this configure for catch on the fly and loss of motor phase ( OAC) • In the case of switching motors in parallel use the motor switching function to optimize the motor nameplate parameters • Typical applications: Safe disconnection of the drive output, ATV71 “by-pass” function, switching of motors in parallel Summary Motor torque in delta 87Hz • The isolated motor voltage and the control of flux by the drive allows the variable speed drive to make a 50HZ motor configured in delta turn with constant torque up to 87Hz (104Hz for a 60Hz motor) • In this case the initial power of the motor is multiplied by √3 so it is necessary to choose a drive adapted for this power • Enter the delta motor nameplate data ATV71 – Example : a 2,2 kW, 50 Hz motor wye connected will generate a power of 3,8 kW at 87 Hz when connected in delta – UNS = 220, FRS=50, NCR=6.4, NSP=1420, COS=0.80 an auto-tune(TUN) – Set Tfr >=87hz to authorize this frequency in HSP Summary High speed motors • The output frequency of the ATV71 can go up to 1000Hz (500Hz >37kW) which allows the control of high speed motors (grinders, saws …) • The point Volts/Hertz law permits the adaptation of the V/f profile to avoid resonances • The inductance of these motors can sometimes be low and then it is necessary to increase the chopping frequency and in certain cases add an output inductor to smooth the current and improve the torque performance • Because of their design, this type of motor is more sensitive than a standard motor to motor overvoltages so use an overvoltage limiter or an output filter ATV71 Summary Single phase motors • If it is a t hree phase mot or using a capacit or t o reconst itute a phase, remove t he capacitor and connect U, V, W to the motor • Wit h a « true » single phase asynchronous mot or, correct operation is not guaranteed In order t o start them, a second winding off set by 90° is insert ed into t he stat or T his auxiliary phase if powered through a dephasing device (either a capacit or or an inductor) and once the motor is st arted the auxiliary phase is shorted • If t he mot or is equipped with a capacitor it must be shunted once the st art -up is terminated (risk of overheat ing as a result of t he chopping f requency) • It must be tested wit h t he f ollowing recommendations: – – – – – – – ATV71 Verify t hat the motor has an insulat ion class suff icient t o sustain t he DC volt age bus voltage(mains volt age *SQR2) Connect the mot or t o U and W Ent er the mot or nameplat e dat a (UNS,FRS, NCR, NSP), with the chopping frequency at minimum Choose the Volts/Hert z law Deact ivat e the sensing of output phase loss: OPL=no Reduce UFR For the first try, set a ramp that is not t oo short (>5s) Summary Motors of a different size than the drive ATV71  Motor power greater than the power of the drive • The use of a motor greater than the size of the drive is possible under the condition that the current used by the motor is less than or equal to the nominal drive current • This facility permits among other things the use of an auto-ventilated motor over a greater speed range during normal operation Summary Motors of a different size than the drive ATV71  Motor power lower than the drive power • The ATV71 can power motors of a smaller power than the drive nominal power (the motor name plate must bet set) • Minimum of 20% of the drive size to conserve performance • It is possible to run smaller motors but the performance and protection is not guaranteed • This facility permits the use of the drive on applications requiring large intermittent overtorques • Typical Applications: machine requiring very great starting torque, crushers, mixers, synchronous motors Summary Thanks For your attention 12/28/15 Bertrand Guarinos STIE ATV71 M3 commande moteur R2 EN Summary 112 ... Summary The motor control I ATV71 The motor control laws • • • • • The basics of flux vector control The voltage flux vector control law SVC U The current flux vector control law SVC I The volts/Hertz... Summary Motor nameplate ATV71 • The parameters of the motor nameplate permit the optimization of the performance of the motor control law • The input of the motor parameters must precede the choice... ATV68 Speed range 10, Torque at 5Hz, Fmax 1000Hz Volts / Hertz Synchronous Motor BO Substitution ATV58 special motor mode Summary The motor control I ATV71 The motor control laws II Motor control