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7.8.4 Stabilization settings
7.8.4.1 Torque stabiliser
The torque stabiliser is basically the first order high-pass filter for the estimated torque [
𝑇
]. The
output of the filter is a frequency correction term
𝑑𝑓
added to the output frequency reference. The
purpose of the torque stabiliser is to stabilise the possible oscillations in the estimated torque. The
controller gain is changing linearly between the zero and field weakening point frequencies. The zero
and field weakening point gains can be controlled independently with gains. The stabiliser operates
at frequencies above 3 Hz.
The discrete implementation of the filter is:
1000
𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝 𝑑𝑓
𝑘
=
1000
𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝 𝐺
(𝑇
𝑘
− 𝑇
𝑘−1
) + 𝑑𝑓
𝑘−1
= 𝐺
𝑓
(𝑇
𝑘
− 𝑇
𝑘−1
) + 𝑑𝑓
𝑘−1
Where
𝐺
𝑓
is the total gain of the filter. The gain and the corner frequency of the filter is controlled by
the following parameters
P2.8.7.1 Torque stabiliser Gain ID1412
“TorqStabGain”
These parameters define together with the Torque Stabiliser Damping the actual gain of
the filter. Torque Stabiliser Gain is the gain at the zero frequency. Torque stabiliser Gain
in FWP is the gain at the field-weakening frequency. The gain changes linearly with the
frequency between these two points so that the gain is
𝐺 = TorqStabG TorqStabGain −
f
f
FWP
TorqStabGain, if f < f
FWP
𝐺 = TorqStabGainFWP, if f ≥ f
FWP
The final gain is obtained by considering the value of Torque Stabiliser Damping and the
scaling in which 256 means the gain 1. So, the final and the actual gain of the filter is
obtained from
𝐺
𝑓
=
1000 ∗ 𝐺
256 ∗ 𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝
P2.8.7.2 Torque stabiliser damping ID1413
“TorqStabDamp”
If a PMS motor is used in open loop control mode, it is recommended to use value 980
instead of 800.
The value ‘980’ is set automatically when PMS motor is selected.
This parameter defines the corner frequency of the high-pass filter. The time constant of
the filter is calculated as
𝑇
𝑐
= 𝑇
𝑠
𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝
1000 − 𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝 = 1𝑚𝑠
𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝
1000 − 𝑇𝑜𝑟𝑞𝑆𝑡𝑎𝑏𝐷𝑎𝑚𝑝
It follows that the corner frequency of the filter is obtained from
𝜔
𝑐
=
1
𝑇
𝑐
𝑟𝑎𝑑/𝑠
For example, if Torque stabilizer damping = 600, it follows that
𝑇
𝑐
c = 1.5 ms and
𝜔
𝑐
=
667 rad/s.