Most of the time we aren’t interested in the actual speed of the motor, we just want the conveyer to deliver the package at the right speed, or the air to supply the amount of cooling we want. If we do need more accurate speed control, we can enable slip compensation by setting the motor speed parameter. Vector control does a better job by calculating exactly what the motor does and adjusting accordingly. For real speed control we can fit an encoder to the motor and feed the speed information back to the drive.
The setpoint can be supplied to the drive in various ways. The easiest is to supply a 0 to 10V signal to pin 6 (with respect to pin 7) and the drive will produce an output frequency (by default, when enabled) of 0 to 50Hz (60Hz in US). There’s a 10V output on pin 5, so connect a potentiometer across 5, 6 and 7 and you have control. The input at pin 6 can be recalibrated for offsets and scaling, and can also accept 0 – 20mA, 4 – 20mA, 10 – 0V etc.
If you want to control the frequency from the built in keypad that’s possible, and various options can be selected (different start and control settings, reverse button disabled etc.)
The drive also includes adjustable fixed frequencies which can be selected using digital inputs, so a machine can run at fast, medium or slow fixed speeds.
Control using serial communications allows the setpoint to be continually updated over the the serial port.
The Master Slave controller allows a drive to derive it’s setpoint from a master drive via a simple connection.