Control Mode Vector Control Type of Motor Encoder Features
Volts / Hertz control
mode (V/Hz)
No vector control Induction - usually mu‐
liple connected in par‐
allel
Without encoder
• No fast bypass
• No spinning load
Closed loop vector con‐
trol mode (CLVC)
Vector control Induction With encoder
• Fast bypass option
• Spinning load op‐
tion
Closed synchronous
motor control mode
(CSMC)
Vector control Synchronous With encoder
• Fast bypass option
• Spinning load op‐
tion
Permanent magnet mo‐
tor control mode (PMM)
Vector control Permanent magnet
motor
Without encoder
• Fast bypass option
• No spinning load
• High starting tor‐
que enabled auto‐
matically
Synchronous motor
brushless DC exciter
mode (SMDC)
Vector control Synchronous with DC
exciter
Without encoder
• No fast bypass
• No spinning load
4.7.4 Open Loop Vector Control (OLVC)
Open loop vector control (OLVC) is used for most applications with single induction motors. In
this mode, the control estimates motor slip as a function of load torque, and provides a
performance that matches a vector controlled drive with speed sensor/transducer above a
certain minimum speed. With the correct motor parameters, the control can provide good
performance even at 1% of rated speed.
With this mode, speed feedback is synthesized from the stator frequency and the estimated
motor slip, and slip compensation is automatic.
In this control mode, if spinning load is selected, the drive begins by scanning the frequency
range to detect the speed of the rotating motor. Once the drive has completed the scan or if the
feature is disabled, the drive goes into magnetizing state. During this state, the drive ramps the
motor ux to its commanded value at the specied ux ramp rate. Only when the ux feedback
is within 90% of the commanded ux, the drive changes to the run state. Once in run state, the
drive increases the speed to the desired value. All motor and drive parameters are required for
this mode of operation. Default values for the control loop gains are sucient for most
applications.
NXGPro+ Control Description
4.7 Control Modes
NXGPro+ Control Manual
50 Operating Manual, A5E50491925A
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