6 -142Feed Forward Control Structure• The following block diagram shows the speed controller (ASR) and the feed forward control structure.Fig 6.75 Structure of Speed Controller (ASR) and Feed Forward ControlSetting Precautions• When N5-02 (Motor acceleration time) is not properly set, the acceleration time may not increase. The fac-tory setting of N5-02 depends on the Inverter capacity. When the Inverter capacity is different from themotor capacity, calculate an appropriate acceleration time using the equation given in N5-02 of Chapter 5User Constants or set the time that corresponds to the motor capacity referring to Factory Settings thatChange with the Control Method (A1-02) (Page 5-81)• When setting the feed forward proportional gain (N5-03), take the inertia of the motor to be equivalent to1. If the speed reference response is slow, increase the feed forward proportional gain (N5-03). If over-shoot occurs with the actual speed, or if a negative torque reference is output when acceleration is com-pleted, reduce the feed forward proportional gain (N5-03).• When using the droop control function (i.e., if b7-01 is not set to 0.0), disable feed forward control (i.e., setN5-01 to 0). Droop Control Function (SPEC: E or Later Only)Droop control is a function that allows the user to set the amount of motor slip.When a single load is operated with two motors (such as in a crane conveyor), a high-resistance motor is nor-mally used. This is to use torque characteristics that exhibit proportion movements due to changes in the sec-ondary resistor to maintain torque balance with the load and overall speed balance with the load.If droop control is used, a high-resistance motor characteristics can be set for a general-purpose motor.C5-06FrequencyreferenceFeedforwardcontrollerDetected speedSpeed controller (ASR) Primaryfilter(C5-10)Torque limitL7-01 to L7-04SecondarycurrentreferenceN5-02, N5-03 U1-45U1-44U1-05Motor A’s torquecharacteristicsTATBMotor A’s torque characteristicsTATBMotor B’s torque characteristicsMotor B’s torquecharacteristicsLoad torqueLoad torqueTorqueThe balance of the load is very different with different amounts of slip.TorqueReferencespeedSpeed ReferencespeedSpeedLoad balance when using a general-purpose motor Load balance when using a high-purpose motorThe difference betweenTA and TB is getting larger.The difference betweenTA and TB is getting smaller.
