GB2349992A - Electric motor control system - Google Patents

Abstract

An electric motor control system in which during one phase of operation a dc source 3 provides electric energy to drive a motor and during a second phase, current previously stored in a capacitor 5, supplies energy to the motor in an alternate manner. When a switch 1 is turned on the motor winding is energised and a capacitor 5 is charged. The switch 1 is then turned off and a switch 2 is turned on so that the capacitor 5 is discharged through the motor winding. This operation is repeated in an alternate manner. Switches 1, 2 may be mechanical, magnetic or electronic and may be actuated by the motor or by a drive from a separate motor. Some of the generated ac may be used for other purposes, such as lighting/heating. The motor may be an induction motor (Fig 2) in which two reed switches are used.

Description

41930pb.doc 234.9.992 1 TITLE Electrical Machines Conventional electric

motors, during their operation, utilise electric current s supplied continuously to their winding or windings from a mains or battery source to energise their electromagnet systems. This is not so with such motors designed in accordance with my present invention, their winding(s) only receive electric current from said source intermittently.

In an electric motor working on such a cycle its electromagnet winding or windings are energised at regular predetermined intervals by electric current obtained from an external supply source. In between these intervals current to energise said winding(s) is derived from a condenser or capacitor storage means incorporated therein (said winding(s)) and charged, electrically, during said intervals of supply from an external source, by this supply.

is Theoretically, because the current supply of the motor is intermittent and is virtually utilised twice, the motor should use less current than an electric motor of conventional design without any appreciable loss of power output. This will be more apparent later in this specification. According to this invention, an electric motor includes a condenser or capacitor storage means in its electromagnet winding or windings and a switching provision, variously actuated, and enabling the alternate charging (electrically) from a d.c. source, and discharging of said storage means in opposite directions through said winding(s) thereby inducing rhythmic polarity changes in the magnetic flux system of its electromagnet arrangement(s) 2 conducive to the working of said motor.

Although the current supply to the motor is d.c., since the current flow through the winding(s) of the motor alternates in direction continuously, the invention may be applied to any a.c., universal or undulating current electric s motor design.

The invention will now be further described with particular reference to the accompanying drawings, in which:- Figure 1 is a schematic illustrating the electrical circuits, switching provision and condenser or capacitor storage means 10 involved in a specific arrangement of the invention, and Figure 2 is a diagrammatic end elevation of an induction electric motor in accordance with the invention.

Referring to Figure 1 of the drawings, two switches 1 and 2 control the current flow through the circuit. In practice, a single two way switch may is replace these switches, but not essentially so.

Assuming that switch 1 is closed and switch 2 is opened, as is illustrated, and that current from a D.C. source 3 flows through the winding of an electromagnet 4 interposed in the circuit, to a parallel plate condenser 5, said magnet is energised and said condenser becomes charged electrically. Now suppose switch 1 is opened, thus interrupting the current flow via the circuit from source 3 to condenser 5, and switch 2 is closed, the electrical charge stored in said condenser would then pass back through switch 2 and the right-hand part of the circuit, in the opposite direction, through the winding of magnet 4 to said condenser.

3 The reversal of the direction of the flow of current through the winding of magnet 4 reverses the polarity of said magnet and could, with a suitable means for operating the switches 1 and 2, form a continuous process which is the basis of the invention. It would be a simple matter to arrange for the actuation of the switches 1 and 2 or the like, in the requisite manner either by mechanical or other methods, depending perhaps on the switch system, which may be various, embodied. The alternating field magnetism produced by the magnet 4, which magnet might form or be part of the stator or the rotor of an electric motor of an appropriate kind, i.e. with a rotor, would induce the rotation of the motor's rotor. 10 Either single or multiple electromagnet systems may be featured.

The induction motor example in Figure 2 has a soft iron rotor 6 which rotates in the alternating magnetic field of a stator electromagnet 4, similar reference numerals indicating the similar items in Figure 1. A switch box 7 contains two contact breaker style switches operated by cams and a camshaft optionally driven, directly or indirectly, by a rotor shaft 8 or by a separate small electric motor (not shown). Alternatively, the magnet 4 acts as the rotor of the motor and the "rotor"6 as a magnetised (permanently) or un-magnetised ring stator thereof Likewise the motor may be of so-called squirrel cage design, either the rotor 6 or the stator having this configuration, dependent on which of these devices is the electromagnet (which would not require the said cage modification) and which is not. Other embodiments of the invention are disclosed in my patent specification GB 9310354.7.

Two reed switches, preferably acting through an ordinary magnetic relay 4 means and operated by a small permanent magnet mounted on a spindle driven by the rotor 6 are provided in box 7, Figure 2, in another design.

The rotor winding(s) of still further examples are connected, electrically, in series with their stator electromagnet winding(s) through brushes and slip rings s or a commutator.

The use of any kind of condensers in embodiments is practical, not merely the plate such devices disclosed in the two drawings.

The placing (one above the other) of the condenser 5 and electromagnet 4, Figure 1, in the circuit is reversible. Again, similar reference numerals indicate lo the same components in both figures of the drawings.

Some of the generated a.c. may be for other required purpose(s), e.g. lighting/heating.

Indirect drives to switch boxes through chain and sprocket, belt and pulley, gear train, gear-box and gear-box and shaft systems (from rotor spindles) are contemplated.

Magneto contact breaker style switches are referred to.

Electronic, optical/electronic, trembler and spark gap (like a magneto distributor) switches may also be used.

The right-hand side of the circuit in Figure 1 may, in some instances, mainly to slow the condenser (5) discharge therethrough, embody a resistor provision; for example, in slow speed motor design. Such a device may have a variable electrical resistance, but not essentially so.

The control of the power output and rotor speed of embodiments by the manual and/or automatic regulation of their d.c. supply is understood.

1. An electric motor system including a capacitor storage means in its electromagnet winding or windings and a switching provision, variously actuated, enabling the alternate charging (electrically) from a d.c. source, and discharging of said storage means in Opposite directions through said winding(s) thereby inducing rhythmic polarity changes in the magnetic flux system of its -electromagnet arrangement(s) conducive to the working of said electric motor system.

2. An electric motor system as claimed in claim 1, wherein the operating provision of the switching equipment includes mechanical, magnetic or electronic actuating means.

is 3. An electric motor system as claimed in claim 1, wherein the switching equipment is actuated by the said electric motor system or by a drive from a separate electric motor provided for said purpose.

4. An electric motor system in accordance with any preceding claim, wherein some of the generated A.C. is diverted therefrom for remote usage.

5. An electric motor system substantially as hereinbefore described with reference to the foregoing claim and Figures I and 2 of the accompanying drawings.