Table of Contents
Advertisement
Motor Characteristics
Listed below are some variable speed AC motor
control concepts with which the user of the
Q9 Plus Adjustable Speed Drive should become
familiar.
Motor Autotuning
Motor production methods may cause minor
differences in motor operation. The negative effects
of these differences may be minimized by using the
Autotune feature of the ASD. Autotuning is a
function of the ASD that measures several
parameters of the connected motor and places
these readings in a stored table. The software uses
the information in the table to help optimize the
response of the ASD to application-specific load
and operational requirements. The Autotuning
function may be enabled for automatic tuning,
configured manually at F400, or disabled.
The measured parameters include the rotor
resistance, the stator resistance, the required
excitation inductance, rotational inertia values, and
leakage inductance values.
Pulse Width Modulation
Operation
The ASD uses sinusoidal Pulse Width Modulation
(PWM) control. The output current waveform
generated by the ASD approaches that of a perfect
sine wave; however, the output waveform is slightly
distorted. For this reason, the motor may produce
more heat, noise, and vibration when operated by
an ASD than when operated directly from
commercial power.
Low Speed Operation
Operating a general-purpose motor at lower
speeds may cause a decrease in the cooling ability
of the motor. Reducing the torque requirement of
the motor at lower speeds will decrease the
generated heat at lower speeds.
When the motor is to be operated at low speed
(less than 50% of full speed) and at the rated torque
continuously, a Toshiba VF motor (designed for use
in conjunction with an ASD) is recommended.
Overload Protection Adjustment
The ASD software monitors the output current of
the system and determines when an overload
condition occurs. The overload current level is a
https://www.toshiba.com/tic/
System Characteristics
Q9 Plus ASD Install/Op Manual
percentage of the rating of the motor. This function
protects the motor from overload.
The default setting for the overload detection circuit
is set to the maximum rated current of the ASD at
the factory. This setting will have to be adjusted to
match the rating of the motor with which the ASD is
to be used. To change the overload reference level,
see
Motor Overload Protection Level 1 on pg.
Operation Above 60 Hz
A motor produces more noise and vibration when it
is operated at frequencies above 60 Hz. Also, when
operating a motor above 60 Hz, the rated limit of the
motor or its bearings may be exceeded; this may
void the motor warranty.
Contact the motor manufacturer for additional
information before operating the motor above 60
Hz.
Power Factor Correction
DO NOT connect a power factor correction
capacitor or surge absorber to the output of the
ASD.
If the ASD is used with a motor that is equipped
with a capacitor for power factor correction, remove
the capacitor from the motor.
Connecting either of these devices to the output of
the ASD may cause the ASD to malfunction and
trip, or the output device may cause an over-current
condition resulting in damage to the device or the
ASD.
Light Load Conditions
When a motor is operated under a continuous light
load (i.e., at a load of less than 50% of its rated
capacity) or it drives a load which produces a very
small amount of inertia, it may become unstable
and produce abnormal vibration or trips because of
an over-current condition. In such a case, the
carrier frequency may be lowered to compensate
for this undesirable condition (see Program
Special Carrier Frequency
Frequency).
Note: When operating in the Vector Control
mode the carrier frequency should be
set to 2.2 kHz or above.
Motor/Load Combinations
When the ASD is used in combination with one of
the following motors or loads, it may result in
unstable operation.
182.
PWM Carrier
7
Advertisement
Table of Contents
