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HARSFEN0602
10 The current controller
This section describes the current controller and its parameterization. In addition, it
describes the current limiting process and the amplifier protections.
The commands relevant to the current controller are:
Command Description
TS Current controller sampling time
KP[1] Proportional gain of current controller (nominal voltage)
KI[1] Integral gain of the current controller (nominal voltage)
XP[4] Time constant for DC power bus filter
XP[5] Step limiter for torque command filter
XP[6] Time constant for torque command filter
MC Largest available amplifier current
PL[1] Application peak current limit
PL[2] Duration for the peak current limit
CL[1] Continuous application current limit
Please read about the above instruction in the Command Reference Manual to complement
the material of this chapter.
The Harmonica energizes all the 3 motor terminals simultaneously. This means it has to
control two current components simultaneously. It must control only two current
components, not three, since the phase currents are linearly dependent – the sum of all the
phase currents is identically zero. The Harmonica has a vector current controller. This means
that the two directly controlled current components are:
IQ: The current component that produce magnetic field in the desired direction
(normally perpendicular to the rotor fixed magnet field)
ID: The current components that produce magnetic field orthogonal to the desired
direction (normally parallel to the rotor fixed magnet field)
The structure of the current controller is as follows:
Pre-filter
Torque
command
Q
P+I controller
Output
Coordinate
transform
D
P+I controller
Power bridge
& motor
Input
Coordinate
transform
Va
Vb
Vc
Ia
Ib
Ic
PWM output
Current sensors
-
IQ
ID
-
0
Commutation
angle
VQ
VD
Peak/Continuous limit
saturation
Figure 10: Current controller structure
The input coordinate transform retrieves the IQ and ID (Active and Reactive) components of
the motor currents.
This Chapter deals with currents in Amperes. The definition we use for an "Ampere" of
three-phased motor current is explained in the section
2.3: "Related Software
The Harmonica requires supporting software for setup, tuning, prog
ramming, and