Vector Control With Encoder Feedback - Hitachi SJ700-2 Instruction Manual

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
The motor generates an
Starting
impact when it starts.
Decelerating The motor runs unsteadily.
Torque is insufficient during
Torque-limited
the torque-limited operation at
operation
low frequencies.
Low-frequency
Motor rotation is inconsistent. Increase the motor constant J from the set value.
operation
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%
Symptom
Reduce the motor constant J from the set value.
Reduce the speed response setting.
Reduce the motor constant J from the set value.
Reduce the overload restriction level to lower than
the torque limiter level.
Chapter 4 Explanation of Functions
A001: Frequency source setting
A044/A244: V/F characteristic curve selection,
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
Adjustment method
4 - 99
Related code
1st/2nd motors
Adjustment
item
H024/H034
H005
H024/H034
b021, b041
to b044
H024/H034