Back to results
US 8,427,084 B2Granted
Digital pulse width modulated motor control system and method
OwnerHerbert S. Kobayashiinventor
Life of this patent
Estimating the term…
Abstract
A digital motor control system utilizes at least two variable pulse generators to produce two streams of pulse width modulated pulses to control the motor speed and direction of rotation of a motor. An input control signal may be compared with two reference signals, such as two waveforms which are inverted with respect to each other, to produce two streams of pulse width modulated signals. A logic circuit combines the two streams of pulses.
Claims17
A control system operable for controlling a direction and speed of an electric motor, comprising:
- at least two variable duration pulse generators which produce output pulses at staggered intervals with respect to each other;
- a waveform generator to produce a waveform, said at least two variable pulse generators being operatively connected to said waveform generator;
- a variable control for controlling said at least two variable duration pulse generators to thereby vary a duration of said output pulses whereby said output pulses generated by said at least two variable duration pulse generators in response to said variable control comprise variable width pulses;
- power switch switches which interfaces with said motor, said power switch network producing power pulses responsive to a combination of said output pulses for application to said motor, said power switches being operable to produce power pulses comprising a power pulse duration which varies with said duration of said output pulses;
- and
- a logic circuit operable for combining said output pulses and producing control signals which control forward and reverse rotational direction and speed of said motor.
3 more elements
A method for controlling direction and speed of an electric motor, comprising:
- producing a repeating waveform at a constant repetition rate with a constant cycle duration;
- utilizing a first variable pulse width generator for producing a first group of pulse width modulated pulses which are initiated with respect to a first portion of said repeating waveform;
- utilizing a second variable pulse width generator for producing a second group of pulse width modulated pulses which are initiated with respect to a second portion of said repeating waveform;
- controlling a duration of said first group of pulse width modulated pulses and said second group of pulse width modulated pulses whereby said first group of pulse width modulated pulses generated by said first variable pulse width generator and said second group of pulse width modulated pulses generated by said second variable pulse generator comprise variable width pulses;
- logically combining said first group and said second group of pulse width modulated pulses to produce control signals to control a direction and speed of said electric motor;
- and
- wherein when a combined duration of said first group and said second group of pulse width modulation pulses is greater than said constant cycle duration of said repeating waveform, then driving said electric motor in a first rotational direction, and when a combined duration of said first group and said second group of pulse width modulation pulses is less than said constant cycle duration of said repeating waveform, then driving said electric motor in a second direction opposite to said first direction.
4 more elements
A control system operable for controlling a direction and speed of an electric motor, said electric motor comprising one or more windings, comprising:
- a variable control element;
- at least two variable pulse generators operatively connected to said variable control circuit which generate output pulses with variable width at staggered intervals with respect to each other in response to said variable control element;
- a logic control circuit which receives said output pulses with variable width from said at least two variable pulse generators operable for producing forward control pulses and reverse control pulses which control forward and reverse rotational direction and speed of said electric motor;
- an electric power supply to supply electric power to said electric motor;
- and
- a first pair of power switches responsive to forward control pulses to apply relatively positive pulses to said electric motor, said first pair of power switches comprising a first n-channel power switch and a first p-channel power switch, a source of said first p-channel power switch being commented to a positive pole of said electric power supply, a source of said first n-channel power switch being connected to a negative pole of said power supply;
- and
- a second pair of power switches responsive to reverse control pulses to apply relatively negative pulses to said electric motor, said second pair of power switches comprising a second n-channel power switch and a second p-channel power switch, a source of said second p-channel power switch being commented to a positive pole of said electric power supply, a source of said second n-channel power switch being connected to a negative pole of said power supply.
5 more elements
Dependencies are inferred from the claim text.