Speed control under Real sensorless vector control, vector control, PM sensorless vector
control
198
PARAMETERS
5.3.6 Troubleshooting in the speed control
No. Condition Cause Countermeasure
1
The motor does not
rotate.
(Vector control)
Motor wiring is incorrect.
• Check the wiring.
Set V/F control (set Pr.80 Motor capacity or Pr.81 Number of motor poles
to "9999") and check the motor rotation direction. For SF-V5RU (1500 r/min
series), set Pr.19 Base frequency voltage to "170 V (340 V)" when the
value is 3.7 kW or lower, and set it to "160 V (320 V)" when the value is
higher, and set Pr.3 Base frequency to "50 Hz".
When a forward signal is input, rotation in the
counterclockwise direction as viewed from the motor shaft
direction is correct. (Clockwise rotation means that the
phase sequence of the inverter secondary side wiring is
different.)
Encoder type selection
switch (FR-A8AP (option))
is incorrect.
• Check the encoder specifications.
Check the encoder type selection switch of differential/complementary (FR-
A8AP (option)).
Wiring of encoder is
incorrect.
• When using the system where the motor shaft can be rotated by an external
force other than the motor without any safety troubles, rotate the motor
counterclockwise and check if FWD is indicated.
If REV is indicated, the phase sequence of the encoder is incorrect.
Check the wiring, and set Pr.359 Encoder rotation direction in
accordance with the motor specification. (Refer to page 62.)
If the clockwise direction is forward as viewed from the motor shaft side, set
Pr.359="0".
If the counterclockwise direction is forward as viewed from the motor shaft
side, set Pr.359="1".
The setting of Pr.369
Number of encoder
pulses and the number of
encoder pulses used are
different.
• If the parameter setting value is lower than the number of encoder pulses
used, the motor will not rotate. Set Pr.369 correctly.
Encoder power
specifications are incorrect.
Alternatively, power is not
input.
• Check the encoder power specifications (5 V/12 V/15 V/24 V), and input the
external power supply. When the encoder output is the differential line driver
type, only 5 V can be input. Make the voltage of the external power supply
the same as the encoder output voltage, and connect the external power
supply between PG and SD.
2
Motor does not run at
the correct speed.
(Command speed and
actual speed differ.)
Speed command from the
controller is different from
the actual speed.
The speed command is
affected by noise.
• Check that the speed command sent from the controller is correct. (Take
EMC measures.)
•Set Pr.72 PWM frequency selection lower.
The command speed and
the speed recognized by
the inverter are different.
• Adjust the bias and gain (Pr.125, Pr.126, C2 to C7, C12 to C15) of the
speed command again.
The setting for the number
of encoder pulses is
incorrect.
• Check the setting of Pr.369. (Vector control)
3
The speed does not
accelerate to the
command speed.
Torque shortage.
T
he torque limit is
op
erating.
• Raise the torque limit.
(Refer to the torque limit for speed control on page 185.)
• Increase the capacity.
Only P (proportional) control
is performed.
• Speed deviation occurs under P (proportional) control when the load is
heavy. Select PI control.
4
Motor speed
fluctuates.
Speed command varies.
• Check that the speed command sent from the controller is correct. (Take
EMC measures.)
•Set Pr.72 lower.
•Set Pr.822 Speed setting filter 1 higher. (page 413)
Torque shortage.
• Raise the torque limit.
(Refer to the torque limit for speed control on page 185.)
Speed control gain is not
suitable for the machine.
(Resonance occurs.)
• Perform easy gain tuning.
• Adjust Pr.820 Speed control P gain 1 and Pr.821 Speed control integral
time 1.
• Perform speed feed forward control or model adaptive speed control.
Sensorless
Sensorless
Vector
Vector
PM
PM
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