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Chapter 4 Explanation of Functions
4 - 97
4.3.3 Vector control with encoder feedback
- To use this control function, specify "05" (V2) for the V/F
characteristic curve selection (A044). (You can specify the
vector control with sensor only when the 1st motor control is
selected.)
- Before using this function, be sure to make optimum
constant settings for the motor with reference to Section
4.2.95, "Motor constant selection." Also, set the pulse count
of the encoder to be used.
- You can select the speed control or pulse train position
control mode by the pulse train mode setting (P013).
- When using this function, observe the following precautions:
1) If you use the inverter to drive a motor of which the
capacity is two classes lower than the maximum
applicable capacity of the inverter, you may not be able to
obtain adequate motor characteristics.
2) If the inverter does not accelerate the motor normally or the overload protection operates, check the
phase sequence of the encoder signal. (For forward rotation, phase B normally leads phase A by a
phase angle of 90°.)
You can check the direction of motor rotation with the actual-frequency monitoring function (d008). For
checking with this monitoring function, specify "00" (VC) for the V/F characteristic curve selection
(A044) and make the inverter operate the motor. (Normally, a positive frequency is monitored when a
forward-operation command is input, and vice versa.)
3) If you cannot obtain the desired characteristics from the motor driven under the vector control with
sensor, readjust the motor constants according to the symptom, as described in the table below.
Operation status Symptom Adjustment method
Adjustment
item
Starting
The motor generates an
impact when it starts.
Reduce the motor constant J from the set value. H024/H034
Reduce the speed response setting. H005
Decelerating The motor runs unsteadily.
Reduce the motor constant J from the set value. H024/H034
Torque-limited
operation
Torque is insufficient during
the torque-limited operation at
low frequencies.
Reduce the overload restriction level to lower than
the torque limiter level.
b021, b041
to b044
Low-frequency
operation
Motor rotation is inconsistent. Increase the motor constant J from the set value. H024/H034
Note 1: Always set the carrier frequency (b083) to 2.1 kHz or more. If the carrier frequency is less than 2.1
kHz, the inverter cannot operate the motor normally.
Note 2: When driving a motor of which the capacity is one class lower than the inverter, adjust the torque
limit (b041 to b044) so that the value "α", calculated by the expression below, does not exceed
200%. Otherwise, the motor may be burnt out.
α = "torque limit" x (inverter capacity)/(motor capacity)
(Example) When the inverter capacity is 0.75 kW and the motor capacity is 0.4 kW, the torque
limit value is calculated as follows, based on the assumption that the value "α" should
be 200%:
Torque limit (b041 to b044) = α x (motor capacity)/(inverter capacity) = 200% x (0.4
kW)/(0.75 kW) = 106%
A001: Frequency source setting
A044/A244: V/F characteristic curve selection,
1st/2nd motors
F001: Output frequency setting
b040: Torque limit selection
b041 to b044: Torque limits (1) to (4)
H002/H202: Motor data selection, 1st/2nd motors
H003/H203: Motor capacity, 1st/2nd motors
H004/H204: Motor poles setting, 1st/2nd motors
H005/H205: Motor speed constant, 1st/2nd motors
H020/H220: Motor constant R1, 1st/2nd motors
H021/H221: Motor constant R2, 1st/2nd motors
H022/H222: Motor constant L, 1st/2nd motors
H023/H223: Motor constant Io, 1st/2nd motors
H024/H224: Motor constant J, 1st/2nd motors
H050/H250: PI proportional gain, 1st/2nd motors
H051/H251: PI integral gain, 1st/2nd motors
H052/H252: P proportional gain setting, 1st/2nd
motors
P011: Encoder pulse-per-revolution (PPR) setting
P012: Control pulse setting
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