Franklin Electric CERUS X-DRIVE CXD-003A-4V, Installation And Operation Manual

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ADVANCED APPLICATION OPTIONS
Operation with Permanent Magnet Motors
97
ADVANCED APPLICATION OPTIONS
Operation with Permanent Magnet Motors
Permanent magnet (PM) motors are different than induction motors in that PM motors have magnets
installed in the rotor. A PM motor is more efficient than an induction motor because the PM motor does not
need power to magnetize the rotor. Therefore, a PM motor uses less input power to create the same shaft
power.
Internal PM motors (IPM) have the magnets installed in the rotor laminations rather than on the surface of
the laminations, which are called surface PM motors (SPM).
The X-Drive controls PM motors using Sensorless Vector Control (SVC). SVC can also be used to control
induction motors. SVC is different than scalar (VF) mode in that the drive uses feedback of the 3-phase cur
-
rent to regulate current at startup and adjust frequency of operation for torque compensation.
PM SVC operation has a sequence of three steps:
1. DC Alignment – A DC current and voltage is applied
to the motor to align the rotor to the magnetic poles.
This alignment requires 3 seconds.
2. I/F Control – A controlled current start of the motor is
performed. This technique provides higher starting
torque than VF mode.
3. Advance V/F Control – With the motor started,
frequency compensation stabilizes the current load. Torque compensation adjusts output voltage to
correct for torque control.
1 2 3
Torque Filter T [Motor-15]
Torque Cmp Gain [Motor-17]
I/F Current [Motor-24] (Ld) / PM sensorless low speed zone current level
PM Ld [Motor-10]
PM Lq [Motor-11]
PM Ke Coeff [Motor-13]
PM Rs [Motor-09] (Stator resistance)
PM Ke Coeff [Motor-13]
PM Bandwidth HS [Motor-25] (high frequency)
PMSVC Fltr Gain [Motor-26]
3-phase current feedback
Torque
compensation
control
Acc./Dec.
F comp
VSR
Inv.
Park
IGBT
&
PWM
PM
Park
Clarke
abc
to
dq
la lb lc
+
0
d-axis voltage
command
q-axis voltage
command
d-axis current feedback
q-axis current feedback
Electrical angle
ld
lq
Ud
Uq
ld
lq
V
comp
ld
lq
Ud
Uq
+
Ud
Uq
iα
iβ
ωr ω1
θs
ƒcomp
Uα*
Uβ*