Rockwell Automation 20B PowerFlex 700 AC Drives Vector Control (v4.001 and up) - Manual (Page 121)

Rockwell Automation Publication 20B-UM002G-EN-P - July 2014 121
Application Notes Appendix C
Vector Control can operate in one of two configurations:
1. Encoderless
Not to be confused with Sensorless Vector above, Encoderless Vector
based on Allen-Bradley’s patented Field Oriented Control technology
means that a feedback device is not required. Torque control can be
achieved across a significant speed range without feedback.
2. Closed Loop (with Encoder)
Vector Control with encoder feedback utilizes Allen-Bradley’s Force
Technology™. This industry leading technology allows the drive to control
torque over the entire speed range, including zero speed. For those
applications that require smooth torque regulation at very low speeds or
full torque at zero speed, Closed Loop Vector Control is the answer.
Speed Regulators
Any of the PowerFlex drives, regardless of their motor control technology (Volts/
Hz, Sensorless Vector or Vector) can be set up to regulate speed. Speed regulation
and torque regulation must be separated to understand drive operation.
The PowerFlex 700 can offer improved speed regulation by adding speed
feedback. Using a speed feedback device (encoder) tightens speed regulation to
0.001% of base speed and extends the speed range to zero speed.
Motor DC Injection The Motor DC Injection feature allows DC injection braking to be enabled by
using a digital input when the drive is stopped. Programming the digital input
through parameters 361…366 activates the DC injection braking. Firmware
revisions before 10.001 only allowed DC injection braking to occur during a stop
sequence of the drive. Firmware revisions 10.001 and later allow the flexibility to
turn on DC injection after the drive has stopped, as long as there are no faults and
the drive is enabled. To select this feature, the “MtrDC Inject” (69) option has
been added to [Digital Inx Sel], parameters 361…366 (see
page 63 ). The level of
DC brake current injected into the motor is defined in [DC Brake Level],
parameter 158. Bit 5 (“DC Braking”) of [Drive Status 2], parameter 210 will
indicate when the DC injection brake input is high.