Hitachi WJ200 Series User Manual

3−24
Manual Torque Boost – The Constant
and Variable Torque algorithms
feature an adjustable
torque boost
curve. When the motor load has a lot of
inertia or starting friction, you may
need to increase the low frequency
starting torque characteristics by
boosting the voltage above the normal
V/f ratio (shown at right). The function
attempts to compensate for voltage
drop in the motor primary winding in
the low speed range.
The boost is applied from zero to the base frequency. You set the breakpoint of the boost
(point A on the graph) by using parameters A042 and A043. The manual boost is
calculated as an addition to the standard V/f curve.
Be aware that running the motor at a low speed for a long time can cause motor
overheating. This is particularly true when manual torque boost is ON, or if the motor
relies on a built-in fan for cooling.
Voltage gain – Using parameter A045 you can
modify the voltage gain of the inverter (see
graph at right). This is specified as a
percentage of the full scale output voltage.
The gain can be set from 20% to 100%. It
should be adjusted in accordance with the
motor specifications. Gain can be changed
even during operation in V/f mode, and while
stopped in SLV mode. When the setting is
changed , reset (RS terminal on/off) is to be
executed so that the motor constants are
re-calculated.
After the setting is done, please be sure to reset (terminal RS on/off) to recalculate
the motor constant.
Refrain from change the setting value suddenly (within 10%). Inverter may
overvoltage trip due to the rapid change of output voltage.
Voltage compensation gain and slip compensation gain – Using parameters A046 and
A047, you can obtain better performance under automatic torque boost mode (A041=01).
See following table for the concept of adjustment, including other parameters.
Symptom Adjustment Adjust item
Motor torque is not enough at low speed
(The motor does not rotate at low speed)
Increase the voltage setting for manual torque
boost, step by step
A042 / A242
Increase the voltage compensation gain for
automatic torque boost, step by step
A046 / A246
Increase the slip compensation gain for
automatic torque boost, step by step
A047 / A247
Reduce carrier frequency
b083
Motor speed decreases (stalls) when a Increase the slip compensation gain for
A047 / A247
100%
fbase
fmax
A045=100
80%
A045=80
V
0
0
5% voltage
boost
(100%=
A082)
A042 = 5 (%)
fbase = 60Hz30Hz
V
100%
1.8Hz
A043 = 3 (%)
Hz
A

Hitachi WJ200 Series Specifications

General

Series	WJ200
Output Frequency	0.1 to 400 Hz
Control Method	V/f Control, Sensorless Vector Control
Overload Capacity	150% for 60 seconds
Enclosure	IP20
Communication	RS-485 (Modbus RTU)
Input Voltage	200-240V AC, 380-480V AC
Ambient Temperature	-10 to +50°C
Storage Temperature	-20 to +60°C
Humidity	5 to 95% RH (non-condensing)
Cooling Method	Fan cooled
Braking Unit	Built-in
Protection Functions	Overcurrent, Overvoltage, Undervoltage, Overheat, Ground Fault
Analog Inputs	2
Analog Outputs	1