Pr 3.18 = motor + load inertia (it is possible to measure the load inertia as part of the auto-tuning process, see Pr 5.12 on page 75), Pr 5.32 = motor

torque per amp.

Ki = J / (Kc x Kt) x (2 x Bandwidth / Kbw)

Where: Kbw = [ (2

+ 1) + ((2

Kp = 2  [(Ki x J) / (Kc x Kt)] = 2  [(Pr 3.11 {SP02, 0.62} x Pr 3.18) / (rated drive current x Pr 5.32)]

2: Kp gain times 16

If this parameter is set to 2 the Kp gain (from whichever source) is multiplied by 16. This is intended to boost the range of Kp for applications with very

high inertia. It should be noted that if high values of Kp are used it is likely that the speed controller output will need to be filtered (see Pr 4.12) or the

speed feedback will need to be filtered (see Pr 3.42). If the feedback is not filtered it is possible the output of the speed controller will be a square

wave that changes between the current limits causing the integral term saturation system to malfunction.

3.18

Motor and load inertia

Bit

Coding

Range

0.00000 to 90.00000 kg m

Default

0.00000

Update rate

Background (1s) read

The motor and load inertia represents the total inertia driven by the motor. This is used to set the speed controller gains (see Pr 3.13) and to provide

torque feed-forward terms during acceleration when required (see Pr 4.11). It is possible to measure the inertia as part of the autotune process, see

Pr 5.12 {SE13, 0.34}.

Bandwidth

3.20

Bit

Coding

Range

0 to 50 Hz

Default

1 Hz

Update rate

Background (1s) read

The bandwidth is defined as the theoretical 3dB point on the closed-loop gain characteristic of the speed controller as a second order system. At this

point the phase shift is approximately 60°. This parameter is used to define the bandwidth used for setting up the speed loop gain parameters

automatically when Pr 3.17 = 1.