Method and drive for elevator DC drive motor stabilization

Claim 1

An elevator speed control stablization system for a DC motor in which speed control current signal and speed signal are used as feedback information, said system comprises: a first and second stablization circuit in circuit relation with respect to one another being in series in a control signal circuit for compensation of three time constants in a speed control loop, practically delay free compliance with respect to speed control signals; said control signal originating at the input to said first stabilization circuit and said second speed control signal originating at the input to said second stablization circuit; said stablization circuit having phase compensation, so that the output of said stablization circuit has a capacitive lead of phase as compared to the input of said stablization circuit; each of said stabilization circuits have operational amplifiers and said first stabilization circuit being able to compensate one time constant, said time constant being a parallel coupling network of resistance and capacitance in circuit with said operational amplifiers; and said second stablization circuit being able to compensate two time constants with the aid of a stabilization circuit, said time constants being a series coupling of resistance and capacitance in circuit with said operational amplifiers; and a portion of the speed control signal is fed to the output of said second stabilization circuit and the output signal of said second stabilization circuit is fed to an additional operational amplifier as the output of said second stabilization circuit, to isolate the stabilization circuits from an ignition circuit firing motor drive thyristors of said DC drive motor.