MICROMASTER 4 (MM4): How do I set up Torque Control on the MM440?
The Torque Control on the MM440 functions extremely well and can be used for tension control etc. providing a few simple set up rules are followed:
- Set the drive up in Sensorless Vector Control first. See the FAQ "MM440: Sensorless Vector Control (SVC)" (FAQ ID: 7494205).
Check the drive functions correctly in SVC, as Torque Control operates using SVC.
- Select the source of the Torque Control setpoint using parameter P1500. Parameter P2003, the reference torque, should be used to define the 100% torque value.
For example, P1500 = 2 will select the analogue input, 0-10V.
- Enable Torque Control by setting P1300 = 22.
- The actual torque (in Nm) can be monitored (whether in Torque Control or not) using r0031; setting P0005 = 31 displays this in the display in place of output frequency. Compare this with the desired torque or the motor torque to give an idea if the scaling is correct.
- If necessary, torque control loop stability may be tuned using the current control parameters P1340 and P1341, but this is not usually necessary.
Remember Torque Control means that if there is no load the motor might run at maximum frequency, so some other limit may be needed, such as a maximum frequency setting (P1082) or an indication of a threshold frequency such as P0731 = 53.4 (refers to P2155) (see below).
Tip 1: Working with Torque and Frequency Control
It is often useful to operate with Frequency and Torque control signals from two separate inputs. This is best achieved by operating the MM440 in Sensorless Vector Control, with the main frequency setpoint derived from analogue input 1, and the torque limit signal derived from the second analogue input (terminals 10 AN+ and 11 AN-). In practice, this means either Frequency or Torque can be in continuous control, while the second input acts as a limiting control, with the controls crossing over as necessary.
- P1000 = 2 (Frequency setpoint from AN1)
- P1300 = 20 (Sensorless Vector Control)
- P1500 = 0
- P1522 = 755.1 (Upper torque limit from AN2)
The second analogue input may be scaled by setting P0756 - P0761... index 1.
The reference torque may be adjusted using P2003.
Tip 2: Working with Negative Torque (e.g. in an unwinder application)
In the above example, if the torque is negative, for example in an unwinding application, AN2 may be connected to P1523, the lower torque limit setting. It is necessary to rescale the AN2 to allow negative values to be set (e.g. 0 to 10V = 0 to -100% torque).
The frequency setpoint may also be scaled appropriately (e.g. AN1 0 to 10V = 0 to -50Hz).
Tip 3: Working with Positive and Negative Torque
If AN2 is to control both positive torque and negative torque, then it is necessary to adjust both P1522 (for example 0 to 100%) and P1523 (for example 0 to -100%) using AN2. This can be achieved by using the inversion of signal that occurs in the PID loop.
- Connect AN2 to PID feedback P2264 = 755.1
- Now connect the scaled output r2272 (normally the same) to the upper torque limit P1522 = 2272.
- Now connect the Error value r2273 (normally 2272 multiplied by -1) to the lower torque limits P1523 = 2273.
- Both the upper and lower torque limits are continuously adjustable from AN2.
The drive will now operate at either one of these limits, or an alternative setpoint such as frequency, current limit etc.
FAQ: "How do I use the JOG function in Torque Control?" Entry-ID: 16818432