US 5,177,416 A · Brushless DC motor · patentgrep

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Abstract

A brushless DC motor which does not have a position sensor for detecting a rotational position of the rotor, is arranged so that conducting phases of the stator windings to be detected are subsequently selected by multi-phase selection signals in response to a conducting state of the stator windings; then, a pulse signal train is generated by detecting the counter electromotive forces induced in the conducting phases subsequently selected and a trapezoidal waveform signal is formed by a slant waveform signal generated in response to the pulse signal train thus obtained. Furthermore, with the trapezoidal waveforms signal thus formed as position signal of the rotor, an electric current signal having a trapezoidal waveform is supplied; to the stator windings, resulting in smooth commutation of the conducting phase of the stator windings. When the motor is to be started, phase commutation of the stator windings is carried out forcibly by means of a pseudo output pulse, thus providing a starting characteristic compatible with that obtained in conventional motors having a rotor position sensor.

Claims57

Dependent claims

A brushless DC motor comprising:

a plurality of stator windings;
a pulse generating means which generates at least one pulse signal train with a different period when starting for commuting the conducting phase of said plurality of stator windings in a successive manner;
a logical pulse generating means for generating a plurality of pulse signals in response to a pulse train outputted from said pulse generating means;
a position signal forming means for forming a position signal in response to a pulse signal outputted from said logical pulse generating means;
and
a power supply means for supplying electric power to said plurality of stator windings in response to said position signal;
wherein when starting, said pulse generating means outputs a predetermined number of pulse signals having a constant period, followed by continuously outputting a pulse signal having a period 1/N (N is an integer) said constant period.

4 more elements

A brushless DC motor comprising:

a plurality of stator windings;
a counter electromotive force detecting means for generating a pulse signal train from a counter electromotive force induced in a selected one of said plurality of stator windings in response to multi-phase selection signals;
a pulse generating means for generating a delay pulse signal obtained by delaying said pulse signal train;
a selection signal generating circuit for generating said multi-phase selection signals in response to said delay pulse signal;
a logical pulse generating means for generating a plurality of pulse signals in response to said pulse signal train;
a position signal forming means for forming a position signal in response to a pulse signal outputted from said logical pulse generating means;
and
a power supply circuit for supplying said plurality of stator windings with electric power in response to said position signal;
wherein said pulse generating means comprises:
a first counter means for counting a period of said pulse signal train outputted from said counter electromotive force detecting means;
a transmitting means for transmitting a count value of said first counter means to a second counter means;
said second counter means outputting said delay pulse signal delayed by a time proportional or approximately proportional to a period of said pulse signal train from the count value thus transmitted;
and
a clock pulse generating means for outputting a clock signal to said first and second counter means.

11 more elements

A brushless DC motor comprising:

a plurality of stator windings;
a counter electromotive force detecting means for generating a pulse signal train from a counter electromotive force induced in a selected one of said plurality of stator windings in response to multi-phase selection signals;
a pulse generating means which supplies a logical pulse generating means with a delay pulse signal obtained by delaying said pulse signal train when the period of said pulse signal train is within a predetermined range and with a pseudo output pulse signal when the period of said pulse signal train exceeds the predetermined range;
said logical pulse generating means generating a plurality of pulse signals in response to said pulse signal train and said pseudo output pulse signal;
a selection signal generating means for generating said multi-phase selection signals in response to said delay pulse signal;
a position signal forming means for forming a plurality of position signals in response to a pulse signal outputted from said logical pulse generating means;
and
a power supply means for supplying said plurality of stator windings with electric power in response to said position signals.

5 more elements

A brushless DC motor comprising:

a plurality of stator windings;
a counter electromotive force detecting means for generating a pulse signal train from a counter electromotive force induced in a selected one of said plurality of stator windings in response to multi-phase selection signals;
a pulse generating means which outputs a delay pulse signal obtained by delaying said pulse signal train when a period of said pulse signal train is within a predetermined range, and outputs a delay pulse signal different in the amount of delay from said first-mentioned delay pulse signal and a pseudo output pulse signal when the period of said pulse signal train exceeds the predetermined range;
a selection signal generating means for generating said multi-phase selection signals in response to said delay pulse signal;
a logical pulse generating means for generating a plurality of pulse signals in response to said pulse signal train and said pseudo output pulse signal;
a position signal forming means for forming a plurality of position signals in response to a pulse signal outputted from said logical pulse generating means;
a power supply means for supplying said plurality of stator windings with electric power in response to said position signals.

4 more elements

A brushless DC motor comprising:

a plurality of stator windings;
a counter electromotive force detecting means for generating a pulse signal train from a counter electromotive force induced in a selected one of said plurality of stator windings in response to multi-phase selection signals;
a pulse generating means which outputs a delay pulse signal obtained by delaying said pulse signal train when a period of said pulse signal train is within a predetermined range and a pseudo output pulse signal when the period of said pulse signal train exceeds the predetermined range, wherein when more than a predetermined number of said pseudo output signals are continuously outputted, at least one of said pseudo output signals are different in interval to be outputted;
a selection signal generating means for outputting said multi-phase selection signals in response to said delay pulse signal;
a logical pulse generating means for generating a plurality of pulse signals in response to said pseudo output signal and said pulse signal train;
a position signal forming means for forming a position signal in response to a pulse signal from said logical pulse generating means;
and
a power supply means for supplying electric power to said plurality of stator windings in response to said position signal.

5 more elements

Dependencies are inferred from the claim text.