Hitachi SJ Series, User Manual

Page: 235 / 786

12-9-18
Chapter 12 Inverter Function
12.9.12 Control synchronous motor
(permanent magnet motor).
• To use the synchronous motor (permanent magnet
motor) for saving energy.
• Replace an induction motor with a synchronous
motor (permanent magnet motor).
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Things to be noted when conducting the
synchronous motor (permanent magnet motor)
control
• Set an appropriate over current level of the
inverter [bb160]. Do not drive a motor whose
maximum current (demagnetization level) is below
the 150% of [bb160].
* Be aware of the root-mean-square value and the
peak value. The rated output current listed in the
specification table is the root-mean-square
value.
• This is the control mode for the reducing torque
applications where the motor that has the same
frame number as the inverter's rating needs a
torque at the start that is 50% or smaller. If a
certain starting torque is necessary, contact the
sales officer of our company.
• This mode can be used neither in applications that
require a constant torque from low speeds nor in
applications that involve rapid acceleration or
deceleration and that require a large torque from
low speeds. Never use this mode for applications
involving a gravity load, such as lifts.
• Synchronous motors (permanent magnet motors)
cannot be operated by a direct input from the
commercial power supply.
• Multiple synchronous motors (permanent magnet
motors) cannot be driven by a single inverter.
• Synchronous motors (permanent magnet motors)
are more likely to cause over voltage errors than
non-synchronous motors (induction motors). If the
rapid deceleration and/or the direct-current
braking function need to be used, consider the
use of an optional braking resistor, a regenerative
braking unit, a regenerative power converter.
• When a hold brake is used, release the brake
before the motor starts operation. Otherwise, the
motor may lose its synchronism.
• The motor may move in the reverse direction at
the start of its revolution. When a malfunction is
caused by the reverse revolution, use the
initial-position estimation function [Hd132].
• Controlling a synchronous motor (permanent
magnet motor) requires the setting-up of the motor
constant. See, "12.3 Basic Settings for Motor." The
motor constant is data corresponding to one phase
of Y-connection (including wiring).
• Set the carrier frequency [bb101] at a value of
8.0kHz or higher. Some low carrier frequencies
may make the motor generate a lot of heat.
• The tolerable load moment of inertia is 50 times
as large as the motor's moment of inertia or
smaller. Some applications whose loads moment
of inertia exceed the above mentioned range may
result in a performance that is below the desired
one.
• In the case of a long wiring (approximately longer
than 20 m) and in the case of controlling motors
other than out company's, the performance may
be below what are expected from the
characteristics.
• In the case of a long wiring (approximately longer
than 20 m), frequency-synchronized re-start may
cause an over current error.
• Driving a motor whose rated current [Hd108]
exceeds the inverter's rated current or a motor
whose frame number is smaller than the
maximum applicable motor by 2 or more may
result in a performance that is below the desirable
one.
• Set not only the motor's rated current [Hd108] but
also the electronic thermal level [bC110].
• If the initial position estimation is enabled in the
starting method [Hd132], a shrill sound caused by
the position detection action may be heard, but
this sound has nothing to do with any abnormality.
• If the initial position estimation is enabled in the
starting method [Hd132], start the operation from
the state in which the motor stopped. Failure to
acquire the correct position may occur, which may
result in unintended revolution, over current, or
loss of synchronization.
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