GB2366918A

GB2366918A - Self commutating winding for a dc motor; generator winding

Info

Publication number: GB2366918A
Application number: GB0022758A
Authority: GB
Inventors: Norman Albert Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-09-18
Filing date: 2000-09-18
Publication date: 2002-03-20
Anticipated expiration: 2020-09-18
Also published as: GB0022758D0; GB2366918B

Abstract

The invention relates to a brushless self commutating arrangement having thyristors A1..F1 switched by compoles (vertical arrows indicate location) in a motor or a generator having diodes D1...D12. The winding comprising conductors wound as respective two sided coils said sides lying in notionally numbered slots 1-24, the coils sides in even slots being connected to the supply terminals such as to provide a current flow in one direction, and all sides in the old slots connected to the supply terminal such as to provide a current flow in the other direction, all equipotential coils being connected in series to from a group of coils, each group being connected in parallel. Lines a...l show the sequential switching steps of odd and even slot conductors, the pole area being shown between the [].

Description

<Desc/Clms Page number 1> SELF COMMUTATING DIRECT CURRENT MACHINES Field of the Invention Relates to rotatable and linear direct current machines. Prior Art Comprises a11 known methods of constructing a winding including Lap, Wave, Duplex, Triplex, Chorded, A group, A half group, B group, C group, Mush, Concentric, Crossfield, Homo polar, Metadyne, Amplidyne, Magicon etc.

Summary This invention utilises a winding, connected to electrical supply or receiving means arranged to provide unidirectional current flow in each slot. The direction is reversed in alternate slots allowing selective control on a slot by slot basis, using compoles to switch off conductors in synchronism with motion. The advantage of this invention is elimination of a mechanical commutator.

It is the object of this invention to provide a means for self commutating a winding of a direct current rotatable or linear electrical machine comprising an arrangement of

electrically conducting conductors wound as coils with two sides, so oriented as to develop interactive electrical and electromotive force, installed in notionally numbered slots wherein all coil sides in even numbered slots are connected to electrical supply or receiving means such as to provide current flow in one preferred direction and all coil sides in odd numbered slots are connected to electrical supply or receiving means such as to provide current flow in the opposite direction to current flow in even numbered slots, and where all equipotential coils are connected in electrical series groups, such groups are then connected in parallel, whereby selective sequential switching of odd and even slot conductors will provide said interactive electrical and electromotive force. Preferred Embodiments Preferred embodiments of the invention will now be described with reference to Figure 1A and Figure 1B which, read in conjunction, show a schematic of a winding suitable for a rotatable or linear direct current machine according to the invention. This winding is for a

4 pole machine with 24 slots, 24 coils and one coil side/ slot layer. The design represents a machine in motor mode. The letters on the top row are thyristor circuit letters (eg: slot 1 contains only circuit A conductors, controlled by thyristor A1). The numbers 1 to 24 on the top row are slot numbers. The vertical column of letters (a) to (1) on the left indicate horizontally in sequence, line (a) line (b) etc. The letters A 1 to F 1 in Fig 1B refer to thyristor control devices.

Line (a) depicts 4 poles in position (a), the start position, one of 24 positions during a complete revolution of this armature. Only the first twelve positions are shown. Poles are indicated by brackets enclosing slots. Slots are indicated by vertical lines, two vertical lines equal one slot. Upper and lower coil sides are shown in solid or dashed lines as is conventional. Arrowheads on the vertical lines indicate direction of current flows at appropriate moments in time.

Line (b) shows the 4 poles have moved on one slot to the right relative to the winding.

Line (c) shows a move of one more slot to the right, each

lettered line thus indicating a pole movement of one slot to the right relative to the winding.

Alternating the current flow direction in adjacent slots is achieved by appropriate connection of the coils to current supply or receiving means of the appropriate polarity as shown in Fig. 1.

All coils are connected in parallel except where any two or more coils disposed two pole pitches apart may be connected in series groups, such groups then being connected in parallel.

Figure 1 B shows six electronic control elements labelled A 1 to Fl, inclusive. These may be thyristors or any other control device that will respond to a momentary reverse current flow by turning off.

The number of devices carrying current of any one time is equal to half the total number of devices.

The switching sequence is to de-energise one device while energising one new one, synchronised with rotation. In this example, for lines (a) and (b) the sequence is A, B, C `on'. For lines (c) and (d) the sequence is B, C, D `on' the A device having been switched off and D device switched

`on'. The next sequence is obviously C, D, E, followed by, D, E, F. The next sequence is E, F. A re-energising `A' device and dropping `D'. The next sequence is F, A, B and so on.

Each sequence changing according to the rule that the number of slot movements before the sequence is changed is equal to slots per pole minus nominal pole cover in terms of slots, plus one. In this example there are six slots per pole minus nominal pole cover in terms of slots, plus one, Therefore as there are six slots per pole and the pole covers a nominal five slots (6 - 5) + 1 = 2 slot movements and the switching sequence changes.

Turn Off Switching `off' circuits is accomplished by compoles, the Number, field strength and use of which, is a design decision. In this example, compoles are indicated by an arrow located between pole ends shown above slots 6 and 18 on line (a) and an arrow located between pole ends shown above slots 7 and 19 on line (b). The direction of the arrow indicates the direction of induced current in the conductors below. Consider line (c), with the conductors

and magnetic field system of the compoles in relative motion, conductors in slot 8 will be subjected to a reverse voltage in excess of the circuit driving voltage as they come under the influence of the compole, this will turn off thyristor A, a similar action takes place in slot 20 on line (c). In some slots, the `turn off' action is irrelevant, as the relevant thyristor is already off.

By examination of the wiring diagram the switching sequence is obvious as is the placement of the compoles. The sequence for the first few lines is, line (a), the compoles over slots 6 and 18 turn off circuit F, as F is off already this is of no moment.

Line (b) compoles over slots 7 and 19 turn off D, it is already off.

Line (c) compoles over slots 8 and 20 turn off circuit A as can be seen by the arrows above, this one is relevant. Line (d) switches off E, not relevant.

Line (e) switches off B, relevant.

It will be noted alternate lines are not relevant to the switch `off sequence.

Location of Compoles It will be noted that on drawing 1A on line (a) the inter- polar space either indicates current flow, slots 12 and 24, or no flow, slots 6 and 18. It is in these latter inter-polar paces (2 off) where inter-poles are located. These locations will vary subject to design. Turn On Due to the fast rise time required and provision for starting, convential methods may be required. Generator To utilise a winding exclusively as a generator with the same direction of relative motion, thyristors are removed and diodes D 1 to D 12 as shown on Figure 1 B are required instead.

Design Rules The total number of slots should be a whole number multiple of the number of poles.

The total number of thyristors should be equal to the number of slots divided by the number of coils in series per parallel circuit.

The number of active thyristors should equal half the total number of thyristors.

A winding that includes compoles and has an even number of slots per pole should be chorded.

Claims

CLAIMS 1. An arrangement of electrically conducting conductors wound as coils with two sides, so oriented as to develop interactive electrical and electromotive force, installed in notionally numbered slots wherein, a11 coil sides in even numbered slots are connected to electrical supply or receiving means such as to provide current flow in one preferred direction in such coil sides and all coil sides in odd numbered slots are connected to electrical supply or receiving means such as to provide current flow in such coil sides in the opposite direction to current flow in even numbered slots, and where a11 equipotential coils are connected in electrical series groups, such groups are then connected in parallel, whereby selective sequential switching of odd and even slot conductors will provide said interactive electrical and electromotive force.
2. As in claim 1, further including a commutating means comprising in combination: (a) a current carrying thyristor

<Desc/Clms Page number 10>

(b) a compole magnetic field system so oriented as to interact with said arrangement, at least in part, wherein said thyristor and said arrangement at least in part, are connected in electrical series and means are provided to produce relative motion between said magnetic field and said arrangement, such as to induce a voltage in said arrangement of sufficient magnitude and direction to reverse the current flow through said thyristor when required.