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In vector control, an AC induction or synchronous motor is controlled under all operating conditions like a separately excited DC motor. [21] That is, the AC motor behaves like a DC motor in which the field flux linkage and armature flux linkage created by the respective field and armature (or torque component) currents are orthogonally aligned such that, when torque is controlled, the field ...
The control of flux can be easily achieved through the direct torque control principle. With DTC the inverter is directly controlled to achieve the desired torque and flux for the motor. During flux braking the motor is under DTC control which guarantees that braking can be made according to the specified speed ramp.
DC injection brakes only require a small module located with the other motor switchgear and/or drivers, mounted in a remote and convenient location, whereas a friction brake must be mounted somewhere on the rotating system. Friction brakes eventually wear out with use and require replacement of braking components.
Small variable-frequency drive Chassis of above VFD (cover removed). A variable-frequency drive (VFD, or adjustable-frequency drive, adjustable-speed drive, variable-speed drive, AC drive, micro drive, inverter drive, variable voltage variable frequency drive, or drive) is a type of AC motor drive (system incorporating a motor) that controls speed and torque by varying the frequency of the ...
Thus it is not possible to control the motor if the output frequency of the variable frequency drive is zero. However, by careful design of the control system it is possible to have the minimum frequency in the range 0.5 Hz to 1 Hz that is enough to make possible to start an induction motor with full torque from a standstill situation. A ...
The scalar control has been to a large degree replaced in high-performance motors by vector control that enables better handling of the transient processes. [1] Low cost and simplicity keeps the scalar control in the majority of low-performance motors, despite inferiority of its dynamic performance; [ 3 ] vector control is expected to become ...
For the same application, the program would select a 125 kW gen-set when using a variable frequency drive and a primary reactor bypass with a 30% starting voltage drop, cutting the gen-set in half (Slides 36–39). [5] Energy Savings – "Most motors turn at nearly constant speed. However, much of the time the devices they drive operate at less ...
More advanced controllers employ a microcontroller to manage acceleration, control motor speed and fine-tune efficiency. Two key performance parameters of brushless DC motors are the motor constants K T {\displaystyle K_{T}} (torque constant) and K e {\displaystyle K_{e}} (back-EMF constant, also known as speed constant K V = 1 K e ...