Operating Modes - Emerson unidrive m200 User Manual

Safety Product Mechanical
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2.3

Operating modes

The drive is designed to operate in any of the following modes:
1. Open loop mode
Open loop vector mode
Fixed V/F mode (V/Hz)
Square V/F mode (V/Hz)
2. RFC - A
Without position feedback sensor
2.3.1 Open loop mode
The drive applies power to the motor at frequencies varied by the user. The motor speed is a result of the output frequency of the drive and slip due
to the mechanical load. The drive can improve the speed control of the motor by applying slip compensation. The performance at low speed depends
on whether V/F mode or open loop vector mode is selected.
Open loop vector mode
The voltage applied to the motor is directly proportional to the frequency except at low speed where the drive uses motor parameters to apply the
correct voltage to keep the flux constant under varying load conditions.
Typically 100 % torque is available down to 1 Hz for a 50 Hz motor.
Fixed V/F mode
The voltage applied to the motor is directly proportional to the frequency except at low speed where a voltage boost is provided which is set by the
user. This mode can be used for multi-motor applications.
Typically 100 % torque is available down to 4 Hz for a 50 Hz motor.
Square V/F mode
The voltage applied to the motor is directly proportional to the square of the frequency except at low speed where a voltage boost is provided which is
set by the user. This mode can be used for running fan or pump applications with quadratic load characteristics or for multi-motor applications. This
mode is not suitable for applications requiring a high starting torque.
2.3.2 RFC-A mode
Rotor Flux Control for Asynchronous (induction) motors (RFC-A) encompasses closed loop vector control without a position feedback device
Without position feedback sensor
Rotor flux control provides closed loop control without the need for position feedback by using current, voltages and key motor parameters to estimate
the motor speed. It can eliminate instability traditionally associated with open loop control for example when operating large motors with light loads at
low frequencies.
Unidrive M200 / M201 User Guide
Issue Number: 4
Electrical Getting Basic
installation started parameters
Running the NV Media
Optimization
motor Card
Advanced
Technical data Diagnostics
parameters
UL Listing
13