Electricity: motive power systems – Switched reluctance motor commutation control
Patent
1996-05-03
1998-11-10
Cabeca, John W.
Electricity: motive power systems
Switched reluctance motor commutation control
318705, 318721, 388815, 388822, H02P 602
Patent
active
058349111
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a brushless DC motor system in which a rotating magnetic field is compulsorily supplied to a rotor in the time of starting to rotate the rotor, and thereafter a voltage pattern of armature coils is changed based on an induction voltage induced at the armature coils.
BACKGROUND ART
As a prior art brushless DC motor system, there is one disclosed in Japanese Patent Publication No. HEI 5-72197. As shown in FIG. 35, the brushless DC motor system includes: a rotor 70 having multipolar permanent magnets; a stator 71 having armature coils 71a, 71b and 71c connected in a three-phase star configuration; a resistor circuit 72 composed of resistors 72a, 72b and 72c connected in a three-phase star configuration in parallel with the armature coils 71a, 71b and 71c, respectively; a rotational-position sensor 73 which detects a rotational-position of the rotor 70 relative to the armature coils 71a, 71b and 71c; a microcomputer 74 which receives a position signal representing the rotational-position of the rotor 70 from the rotational-position sensor 73 and outputs a switching signal to switch a voltage pattern of the armature coils 71a, 71b and 71c; a base drive circuit 75 which receives a switching signal from the microcomputer 74 and outputs a commutation control signal for switchingly controlling the voltage pattern of the armature coils 71a, 71b and 71c; and an inverter section 80 which receives the commutation control signal from the base drive circuit 75 and changes the voltage pattern of the armature coils 71a, 71b and 71c.
The inverter section 80 is comprised of three transistors 80a, 80b and 80c connected to a positive side of a DC power source 76 via a switch 77 and three transistors 80d, 80e and 80f connected to a negative side of the DC power source 76. Collectors of the transistor 80a and the transistor 80d are connected to each other, collectors of the transistor 80b and the transistor 80e are connected to each other, and collectors of the transistor 80c and the transistor 80f are connected to each other. A connection portion of the transistors 80a and 80d is connected to the armature coil 71a of U-phase, a connection portion of the transistors 80b and 80e is connected to the armature coil 71b of V-phase, and a connection portion of the transistors 80c and 80f is connected to the armature coil 71c of W-phase. Then, the commutation control signal from the base drive circuit 75 is inputted to bases of the transistors 80a through 80f of the inverter section 80.
The rotational-position sensor 73 includes: a differential amplifier 81 which receives an input of a voltage V.sub.M at a neutral point of the resistor circuit 72 and a voltage V.sub.N at a neutral point of the armature coils 71a, 71b and 71c, and outputs a voltage difference signal V.sub.MN representing a voltage difference between the neutral point of the resistor circuit 72 and the neutral point of the armature coils 71a, 71b and 71c; an integrator 82 which receives the voltage difference signal V.sub.MN from the differential amplifier 81 and integrates the voltage difference signal V.sub.MN ; and a zero-cross comparator 83 which receive a signal obtained by integrating the voltage difference signal V.sub.MN from the integrator 82, and outputs a position signal. Input terminals of a comparator 84 is connected to both ends of the armature coil 71c, and operates to output a signal representing the polarity of an induced voltage Ew to the microcomputer 74.
In the above-mentioned brushless DC motor system, assuming that motor terminal voltages of the U-phase, V-phase and W-phase from the inverter section 80 are Vu, Vv and Vw and induced voltages of the U-phase, V-phase and W-phase of the armature coils 71a, 71b and 71c are Eu, Ev and Ew, then the voltage V.sub.M at the neutral point of the resistor circuit 72 and the voltage V.sub.N at the neutral point of the armature coils 71a, 71b and 71c are expressed by the equations: of the resistor circuit 72 and the neutral point of the armature coils 71a, 71b
REFERENCES:
patent: 4295085 (1981-10-01), Lafuze
patent: 4565957 (1986-01-01), Gary et al.
patent: 4591767 (1986-05-01), Koide
patent: 4641066 (1987-02-01), Nagata et al.
patent: 4949021 (1990-08-01), Rozman et al.
patent: 5512811 (1996-04-01), Latos et al.
patent: 5581168 (1996-12-01), Rozman et al.
Cabeca John W.
Daikin Industries Ltd.
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