Troubleshooting In The Speed Control - Mitsubishi Electric 800 Series Instruction Manual

Speed control under Real sensorless vector control, vector control, PM sensorless vector
5.3.6

Troubleshooting in the speed control

Sensorless Vector Sensorless Sensorless
No. Condition
The motor does not
1 rotate.
(Vector control)
Motor does not run at
the correct speed.
2
(Command speed and
actual speed differ.)
The speed does not
3 accelerate to the
command speed.
Motor speed
4
fluctuates.
Vector Vector PM PM PM
Cause
• 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.
Motor wiring is incorrect.
Encoder type selection • Check the encoder specifications.
switch (vector control Check the encoder type selection switch of differential/complementary
compatible option) is (vector control compatible option).
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.
Wiring of encoder is Check the wiring, and set Pr.359 (Pr.852) Encoder rotation direction in
incorrect. accordance with the motor specification. (Refer to
If the clockwise direction is forward as viewed from the motor shaft side, set
Pr.359 (Pr.852) = "0".
If the counterclockwise direction is forward as viewed from the motor shaft
side, set Pr.359 (Pr.852) = "1".
The parameter setting and • If the parameter setting value is lower than the number of encoder pulses
the number of encoder used, the motor will not rotate. Set Pr.369 (Pr.851) Number of encoder
pulses used are different. pulses correctly. (Refer to
• Check the encoder power specifications (5 V/12 V/15 V/24 V), and input the
Encoder power
external power supply. When the encoder output is the differential line driver
specifications are incorrect.
type, only 5 V can be input. Make the voltage of the external power supply
Alternatively, power is not
the same as the encoder output voltage, and connect the external power
input.
supply between PG and SD.
The option to be used and • Correctly set Pr.862 Encoder option selection according to the option to
parameter settings do not be used. (Refer to
match.
Speed command from the • Check that the speed command sent from the controller is correct. (Take
controller is different from EMC measures.)
the actual speed. • Set Pr.72 PWM frequency selection lower.
The speed command is
affected by noise.
The command speed and • Adjust the bias and gain (Pr.125, Pr.126, Pr.902 to Pr.905, Pr.917, Pr.918)
the speed recognized by of the speed command again.
the inverter are different.
The setting for the number • Check the setting of Pr.369 (Pr.851). (Vector control) (Refer to
of encoder pulses is
incorrect.
Enable the online auto tuning at startup (set Pr.95 (Pr.574) = "1") (under Real
The motor constant varies
sensorless vector control). (Refer to
due to increase in the motor
To perform the online auto tuning at startup for a lift, use of the Start-time
temperature.
tuning start external input (X28) signal is recommended.
Torque shortage. • Raise the torque limit.
The torque limit is (Refer to the torque limit for speed control on
operating. • Increase the capacity.
Only P (proportional) control • Speed deviation occurs under P (proportional) control when the load is
is performed. heavy. Select PI control.
• Check that the speed command sent from the controller is correct. (Take
EMC measures.)
Speed command varies.
• Set Pr.72 lower.
• Set Pr.822 Speed setting filter 1 higher.
• Raise the torque limit.
Torque shortage.
(Refer to the torque limit for speed control on
• Perform easy gain tuning.
Speed control gain is not
• Adjust Pr.820 Speed control P gain 1 and Pr.821 Speed control integral
suitable for the machine.
time 1.
(Resonance occurs.)
• Perform speed feed forward control or model adaptive speed control.
Countermeasure
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.)
page 64.)
page 141.)
page 444.)
page
(page
page
PARAMETERS
control
page 64.)
page 64.)
154.)
400)
154.)
171
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