초록 ▼

A method is presented in which at least one of the sinusoidal voltages (US) which is induced in the stator windings by the residual magnetism or remanence of the rotor in a rotating-field machine, the frequency of which corresponds to the rotor speed is converted into a symmetrical square wave signa

A method is presented in which at least one of the sinusoidal voltages (US) which is induced in the stator windings by the residual magnetism or remanence of the rotor in a rotating-field machine, the frequency of which corresponds to the rotor speed is converted into a symmetrical square wave signal, (UR), the frequency and the phase of this square wave signal (UR) matching with the frequency and the phase of the induced sinusoidal voltage (US). From this square wave signal (UR), an output signal (UDA) proportional to the frequency thereof is generated. Thus, a method is obtained by which the time required for finding the operational speed of the rotating-field machine (2) is reduced considerably so that a frequency converter can be connected to the rotating-field machine (2) rapidly at a synchronous speed.

대표청구항 ▼

A method of determining the rotational speed of a rotating polyphase motor having stator windings and rotor windings comprising: sensing at least two sinusoidal voltage signals induced in two corresponding stator windings by remanence from said rotor windings, said sinusoidal signals having correspo

A method of determining the rotational speed of a rotating polyphase motor having stator windings and rotor windings comprising: sensing at least two sinusoidal voltage signals induced in two corresponding stator windings by remanence from said rotor windings, said sinusoidal signals having corresponding phases and a frequency indicative of said rotational speed; converting said sinusoidal signals into respective square wave signals wherein each square wave signal is converted by monostable multivibrators into first and second pulse signals, each pulse signal having a duty cycle, with said first pulse signals being separated in time from said second pulse signal; and generating an output signal which is proportional to the frequency of said first and second pulse signal.