DIRECT CURRENT MOTOR COMMUTATION SYSTEM RESPONSIVE TO C.E.M.F.

• US 3,663,878 A
• Filed: 08/26/1970
• Issued: 05/16/1972
• Est. Priority Date: 08/28/1969
• Status: Expired due to Term

• Current Assignee: Takao Miyasaka
• Original Assignee: Takao Miyasaka
• Inventors: Miyasaka, Takao
• Primary Examiner(s): Simmons, G. R.
• Application Number:
  US05/066,911
• Time in Patent Office: 629 Days
• Field of Search: 318/439,138,254,696,695,345,331
• US Class Current: 318/400.34
• CPC Class Codes: H02P 6/14 Electronic commutators

Abstract

A commutatorless type direct current (DC) motor which has a rotor made of permanent magnet. Stator windings are sequentially passed with a current of constant phase rotation and thereby the rotor is initiated to rotate. After starting, counter electromotive forces induced in the stator windings are used for detecting the rotation angle of the rotor. Adequate currents are thereby made to flow in the stator windings and a steady rotation of the rotor is continuously performed.

Claims

1. A direct current motor which comprises:

a permanent-magnet rotor;

a stator disposed concentrically of the rotor;

stator windings wound on parts of the stator and having ends connected to each other at a star point in multiphase star connection;

a power source having one terminal connected between the star point of the stator windings and having its other terminal connected to respective other ends of the stator windings; and

control circuit means interposed between said power source and said respective other ends of the stator windings, said control circuit means including a plurality of identical control stages which are equal in number to that of said stator windings, each one of said control stages including two resistors connected between said respective other ends of two adjacent stator windings;

a first transistor circuit interposed to connect one of said respective other ends of the stator windings to the other end of the power source;

capacitors connected, to earth a connecting point of said resistors through the capacitors;

a first transistor connected between one of said respective other ends of the stator windings and said other terminal of the power source to control flow of current through the associated stator winding, and a second transistor circuit adapted to be in conductive state or nonconductive state by time constant circuits of the resistors and the capacitors when said capacitor means are charged to more than a predetermined voltage, said second transistor circuit switching the first transistor circuit sequentially to be in conductive state or non-conductive state, and wherein counter electromotive forces are induced in said stator windings by rotation of the rotor after starting and wherein the charging time of said capacitors is quickened by the counter electromotive force.

2. The motor of claim 1 wherein the permanent magnet rotor is magnetized to form two poles in diametral directions thereof, in which said parts of the statOr are three salient poles and said stator windings are respectively wound on the salient poles provided in the stator, said stator windings being connected to each other in a three phase star connection.

3. The motor of claim 1, in which said resistors are respectively two resistors connected in series which have respectively different resistance value, said resistors being respectively connected between the other ends of the stator windings, and in which said capacitors are respectively two capacitors connected in series connected between connection points of the series resistors and ground.

4. The motor of claim 1 in which said first transistor circuits include first transistors having respective emitters connected to the other ends of the power source, collectors connected to the other ends of the stator windings, and bases connected to the second transistor circuits.

5. The motor of claim 4 in which said second transistor circuits include second transistors having respective emitters connected to the bases of the first transistors and bases connected to the capacitors.

6. The motor of claim 1 in which said resistors are respectively two resistors connected in series which have respectively different resistance value, said resistors being respectively connected between the other ends of the stator windings, and said second transistor circuits include transistors having respective bases connected to connection point of the series resistors through the capacitors, said transistors actuated by voltages of the connection points.

7. The motor of claim 1 in which, during a transition period from rotation starting to normal rotation, counter electromotive forces are generated by the rotation of the permanent magnet rotor in the stator windings through which phase rotation current is not flowing, and thereby a speed of the phase rotation is increased.