Panasonic Minas-LIQI Series Technical Reference

Contents

№SR-ZSV00039 － 44 －Motor Business Unit, Appliances Company, Panasonic Corporation5－2－5 Feed Forward FunctionPosition deviation can be reduced and response can be improved in comparison with controlling byfeedback only, but also using the velocity feed forward function, which calculates speed control commandrequired for operations on the basis of internal position command and adds the calculation to speed control,which is calculated by comparison with position feedback.The torque feed forward function, which calculates torque command required for operations on the basis ofspeed control command and adds the calculation to torque command calculated by comparison with speedfeedback, improves responses of the speed control system.1）Related parametersusing two feed forward functions, velocity feed forward and torque feed forwardCategory No. Parameter Setup range Unit Function1 10 Velocity feed forwardgain 01000 0.1%This adds a value, which is obtained by multiplying a speedcontrol command calculated on the basis of internal positioncommand with a ratio of this parameter, to a speed commandfrom position control process.1 11 Velocity feed forwardfilter 06400 0.01 msA time constant of primary delay filter is specified for inputting tovelocity feed forward.1 12 Torque feed forwardgain 01000 0.1%This adds a value, which is obtained by multiplying a torquecommand calculated on the basis of speed control commandwith a ratio of this parameter, to a torque command from speedcontrol process.1 13 Torque feed forwardfilter 06400 0.01 msA time constant of primary delay filter is specified for inputting totorque feed forward.2）Example of using velocity feed forwardVelocity feed forward is made valid by gradually increasing velocity feed forward gain with velocityfeed forward filter specified at approximately 50 (0.5 ms). Position deviation during operation at aconstant speed becomes smaller as expressed by the following equation, in accordance with a value ofvelocity feed forward gain.Position deviation [Command unit] = Command speed [Command unit/s]/position loop gain[1/s]  (100 - velocity feed forward gain [%]) / 100Command speedMotor speedPosition deviationPosition deviation at a constant speed becomes smaller as a value of speed feed forward gain is increased.Speed FF gain50[%]80[%]0[%]TimeIf a gain is specified as 100 [%], position deviation theoretically becomes “0.” However, this causes significantovershoot in acceleration and deceleration.If an updating cycle of position command input is longer than a control cycle of drive, or if pulse fre-quencies are uneven, operating noise may be louder when velocity feed forward is valid. In that case,use position command filter (Primary delay/FIR smoothing) of specify a higher value for velocity feedforward filter.3）Example of using torque feed forwardTo use torque feed forward, inertia ratio must be specified correctly. Use an estimated value used for operation ofreal-time auto tuning again, or specify an inertia ratio calculated on the basis of machine specifications for Pr0.04 “Inertiaratio.”Torque feed forward is made valid by gradually increasing torque feed forward gain with torque feed forward filter