Motor control system

A control system for driving an electric motor at a predetermined rotational speed, comprising a power source for driving the electric motor, switching means connected between the motor and the power source for applying discontinuous pulse driving currents thereto from the power source, the motor and switching means being connected in series with the power source, tacho-generator means for producing an output corresponding to the rotational speed of the motor, analog-to-digital transforming means responsive to said tacho-generator means and coupled with said switching means for transforming an analog signal of the output of said tacho-generator means to digital signals to cause said switching means to discontinuously switch current from said power source to the motor so as to maintain the electric motor at a desired rotational speed wherein said analog-to-digital transforming means including a shaper circuit for producing square waves from said tacho-generator means, a bistable circuit responsive to the output of said shaper circuit, a monostable circuit responsive to said bistable circuit so as to be synchronized therewith and producing pulses in each cycle having a constant time period, a second bistable circuit for producing a substantially constant output when the cyclical period of the output of said first bistable circuit is less than a predetermined relation to the constant time period and for producing an asymmetrical pulse output when the cyclical period at the output of said first bistable circuit is greater than the constant time period.

A control system for driving an electric motor at a predetermined rotational speed, comprising a power source for driving the electric motor, a first switching means connected between the motor and the power source for applying discontinuous pulse-driving currents thereto from the power source, control means coupled to the motor for producing a signal having a first component corresponding to the rotational speed of the motor and a second component having a frequency higher than the frequency of the first component, a second switching means which has a predetermined level of inversion connected between said control means and said first switching means and detects signal of said control means, said second switching means being inverted when the signal reaches a predetermined value and causing said first switching means to discontinuously switch current from said power source to the motor so as to maintain the electric motor at a desired rotational speed, said control means including generator means coupled to the motor for producing the component corresponding to the rotational speed of the motor, said second switching means including a Schmitt circuit having hysteresis and responsive to both components, the hysteresis of said Schmitt circuit defining a voltage range at the limits of which the Schmitt circuit is reversed, said second component having an absolute value equal to the range so as to remove said hysteresis of said Schmitt circuit.

A control system for driving an electric motor at a predetermined rotational speed, comprising a power source for driving the electric motor, a first switching means connected between the motor and the power source for applying discontinuous pulse-driving currents thereto from the power source, control means coupled to the motor for producing a first signal corresponding to the rotational speed of the motor;

• pulse-generating means for producing a second signal having a frequency higher than the frequency of the first signal, a second switching means which is connected between said first switching means and said control means and to pulse-generating means said second switching means corresponding to the multiple signal of said first signal and second signal and being inversed when the multiple signal reaches a predetermined value and causing the switching of said first switching means so as to flow the current discontinuously from said power source to said motor and maintain said motor at a desired rotational speed, said control means including generator means coupled to the motor for producing said first signal corresponding to the rotational speed of the motor, said second switching means including a Schmitt circuit having hysteresis and responsive to said multiple signal, the hysteresis of said Schmitt circuit defining a voltage range at the limits of which the Schmitt circuit is reversed, said second signal having an absolute value equal to the range so as to remove said hysteresis of said Schmitt circuit.