Toshiba G7 Series Applications Workbook page 41

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Feedback Vector Control (Speed)

Introduction

Many applications require precise speed control regardless of changes in the load conditions.

Toshiba's G7, when properly configured, provides speed regulation as great as 0.01% over a 1000:1

speed range.

Feedback vector control requires feedback from a rotary encoder mounted on the motor. Toshiba

recommends a bi-directional encoder with differential line driver outputs providing 1024 pulses per

revolution.

Refer to the manual provided with the vector feedback option board for instruction on mounting and

wiring the encoder.

To maximize the performance of the motor/drive combination, the G7 must be tuned to the motor.

G7s have mathematical models of all standard efficient and premium efficient Houston-made Toshiba

motors stored in a matrix memory. These motor mathematical models are used by the drive to

increase the motor's low speed torque and to reduce the load's affect on RPM (when compared to its

performance on a V/Hz drive). If a non-Toshiba motor is being used, the G3 can model the motor by

performing an 'auto-tune' or by manual setting of the motor data.

Feedback Vector Control should not be used on:

Multiple Motor Applications (applications where more than one motor is connected to the G7)

Applications where load end inductors, long lead filters, or output transformers are used

High-speed spindle motors

Motors designed for high slip (NEMA design D)

Motors larger than or more than 2 sizes smaller than the G7's nominal Horse Power rating

Before programming the G7 for feedback vector control, connect the motor to the drive and check the

motor's direction of rotation with a forward run command while using a constant volts per hertz

relationship. The motor must rotate CCW (counter clockwise) when viewed from the opposite drive

end when rotating in the forward direction. If the motor's direction of rotation is incorrect, this must be

corrected by reversing any two motor leads either at the G7 or the motor.

The programming example demonstrates the programming required when using a bi-directional,

differential line driver encoder providing 1024 pulses per revolution.

For additional assistance, please contact Toshiba Adjustable Speed Drive Marketing Dept. at (800) 872-2192

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