A look at how the Unidrive SP reduces slip in both open and closed loop applications.
The Control Techniques Unidrive SP is the most advanced AC drive we sell. The SP can be run in open loop, closed loop, servo, and regenerative mode.
In open loop mode the SP has a special feature called Rotor Flux Control (RFC). This is an algorithm built in the drive that gives near closed loop performance in an open loop application.
The inverter will use the phase voltages, currents, motor name plate information and parameters generated by the auto tune facilities to simulate the motor and therefore estimate the speed of the rotor. It then uses this data for drive feedback. This will greatly reduce motor slip and achievable speed regulation is in the order of 0.5%.
When highly accurate speed, torque, or position control is required then a closed loop system is needed. A closed loop system has feedback from a device fitted to the motor (usually an encoder). The encoder (or other feedback device) will tell the drive exactly how fast the rotor is turning so that the drive can offer speed regulation in the order of 0.01%. The encoder will allow the system to all but cancel out the motor slip as it always knows the exact speed of the rotor.
When the drive is in servo mode, the drive will operate in a similar way to a closed loop system.
For more information on the Unidrive SP please click the link below:
Control Techniques Unidrive SP
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