1.3 Features and Advantages of Control Methods
28 YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual
Control
Method
Selection
Open Loop Vector
Control
(OLV)
Closed Loop Vector
Control
(CLV)
Advanced Open Loop
Vector Control
(AOLV)
Notes
Controlled
Motor
Induction Motor -
Zero Servo
Control
*2
No Yes No
Locks servos without an external
position controller to prevent
movement caused by external
force.
Speed Search
*2
Yes - Yes
Immediately estimates (or
detects) motor speed and
direction when coasting to a stop
to quickly start-up the drive
without stopping the motor.
Automatic
Energy-saving
Control
*2
Yes Yes No
Automatically adjusts the voltage
applied to motors to maximize
motor efficiency for all load
sizes.
High Slip Braking
(HSB)
*2
No No No
Increases motor loss to let the
motor decelerate faster than usual
without a braking resistor. Motor
characteristics have an effect on
this function.
Feed Forward
Control
*2
No Yes Yes
Compensates effects of the
system inertia to increase the
speed precision when the load
changes.
KEB Ride-Thru
Function
*2
Yes Yes Yes
Quickly and safely stops the
motor during power loss and
automatically starts operation at
the previous speed when restores
power without coasting the
motor.
Overexcitation
Deceleration
*2
Yes Yes Yes
Sets the V/f higher than the
setting value during deceleration
to increase motor loss and
decrease deceleration time.
Overvoltage
Suppression
Function
*2 *3
Yes Yes Yes
Adjusts speed during
regeneration to prevent
overvoltage.
*1 Select the drive capacity accordingly.
*2 Note these points when you use this function:
• When you can decouple the motor and machine for a test run, use Rotational Auto-Tuning. You must make adjustments to the
control in the range where there is no vibration in the machine after Rotational Auto-Tuning.
• For vector control, use a 1:1 drive to motor ratio. You cannot use vector control when more than one motor is connected to one
drive. Select a drive capacity so that the motor rated current is 50% to 100% of the drive rated current. If the carrier frequency is
too high, the drive rated current is derated.
• Motor loss increases during overexcitation braking and high-slip braking. Use a maximum braking frequency of 5% ED and a
maximum braking time of 90 seconds. After you start high-slip braking, you cannot restart the motor until it stops. Use
overexcitation braking to decelerate over a shorter time at a pre-determined speed.
• Acceleration and deceleration have priority over torque limits in Open Loop Vector Control during acceleration and deceleration
(soft start changes). The drive will not operate until the speed is at the minimum frequency or the reverse direction of motor
rotation when the motor speed decreases because of torque limits during constant speed control. Set L7-07 = 1 [Torque Limit
during Accel/Decel = Proportional & Integral control] to enable torque limits during acceleration/deceleration (for winding
applications).
*3 Do not use this function with hoist application.
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