A PROCESS AND DEVICE FOR CHANGING THE ACTUAL ROTATION SPEED OF A MULTI-PHASE NON-SYNCHRONOUS MOTOR AND A SUITABLE MOTOR SYSTEM FOR APPLYING THE PROCESS

摘要

The stator current has a variable frequency modified in a determined pace in advance. The effective value of the stator current that results is compared with the conduction value. If it is higher, the frequency is kept constant. If then this frequency corresponds to the setpoint value of the rotational speed, the process ends; otherwise, the frequency change again when the effective value falls below the conduction. An alternative network allows to operate, accelerate or slow down the engine by means of a rectifier and an inverter, and in the absence of voltage the stator current is connected to a load resistor. The change in rotational speed may be continuous or sinusoidal, and the shape and dimensions of a sinusoid element provide an indication of the '' torsional rigidity of the drive ''. Passing a star connection to a delta connection, the frequency range can be extended so as to maintain approximately constant torque. For the purposes of the method, it is possible to implement a system of motors consisting of polyphase asynchronous motor, and couple mutually granted on values ​​of 2 or 3 as a quotient of the voltage characteristic values ​​and the frequency service.