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Having thus described a preferred embodiment of the invention, what is
claimed is:
1. A motor having;
rotor means comprising a plurality of permanent magnets each having
opposite polarity poles,
said permanent magnets arranged in a ring with the poles thereof aligned
radially,
said permanent magnets arranged so that the poles thereof are disposed with
circumferentially alternate polarity, and
stator means comprising a plurality of electromagnets arranged in a ring
disposed adjacent said permanent magnets,
said electromagnets each having poles arranged to distribute two
symmetrically-split magnetic fields that interact with the opposing
permanent magnets to provide electromotive torque.
2. The motor recited in claim 1 wherein,
said rotor means includes a pair of rings of permanent magnets arranged
with the poles thereof in alignment and facing toward each other,
said stator means includes a pair of rings of electromagnets arranged with
the poles thereof in alignment and facing away from each other,
said stator means interposed between the pair of rings in said rotor means.
3. The motor recited in claim 2 wherein,
said stator means includes support means for supporting said pair of rings
of electromagnets,
each said ring of electromagnets supported on opposite sides of said
support means.
4. The motor recited in claim 3 wherein,
each electromagnet in each of said rings of electromagnets comprises a pair
of aligned magnetic cores and a common electrical coil thereon.
5. The motor recited in claim 1 including
housing means for enclosing said rotor means and said stator means.
6. The motor recited in claim 5 wherein
both said permanent magnet rotor means and said electromagnet stator means
are displaced at the maximum radial distance within said motor housing
means.
7. The motor recited in claim 6 including,
controller means for supplying control signals to said stator means in
response to input signals supplied to said controller means, and
power current (-) controlling means for operating upon current signals
associated with said stator means,
each of the last named means contained within said housing means and
supported by said stator means.
8. The motor recited in claim 7, wherein
said controller means accommodates five user-programmable modes related to
forward and reverse torque operating modes, forward and reverse
regenerative braking modes, and neutral.
9. The motor recited in claim 8, wherein,
said power current controlling means comprises of dual-functioning
thyristors for both commutation of the electromagnetic stator poles during
the motor operating mode, and polyphase rectification of the generated
voltage during the braking mode.
10. The motor recited in claim 9 including,
source means for supplying a high-frequency, sinusoidal signal,
Hall-effect device means operative to modulate said sinusoidal signal to
produce a cyclo-inverter waveform,
said controller means and said dual-functioning thyristors function to
commutate said electromagnets of said stator means with said
cyclo-inverter waveform.
11. The motor recited in claim 10 wherein,
said source means includes D.C. supply means,
inverter silicon-controlled rectifier means connected in parallel with said
supply means,
inductive means connected in series with said silicon-controlled rectifier
means,
fast recovery diodes connected in parallel with said silicon-controlled
rectifier means, and
capacitive means connected from said supply means to said
silicon-controlled rectifier means.
12. The motor recited in claim 5 wherein,
the combined effective impedance of said electromagnets of said stator
means is connected as the load for high-frequency inverter means located
external to the motor housing.
13. The motor recited in claim 5 including,
cooling means capable of dissipating thermal energy generated by said
electromagnets and electronic power circuitry located within said motor
housing.
14. The motor recited in claim 5 including,
at least one radial fin means provided at the surface of said housing for
the purpose of cooling the apparatus.
15. The motor recited in claim 5 wherein
said housing means comprises a tire mounting rim.
16. The motor recited in claim 6 wherein said Hall-effect sensing means
comprise three terminal digital switches.
17. The motor recited in claim 1 including,
Hall effect sensing means means disposed adjacent to the poles of said
permanent magnets to facilitate precise commutation of the fields of said
electromagnets by means of simplified concentration of the magnetic flux
produced by said permanent magnets.
18. The motor recited in claim 17 wherein,
said Hall effect sensing means includes a Hall effect device, and
at least one flux concentrator pole apparatus for concentrating magnetic
flux from said permanent magnets into said Hall effect device.
19. The motor recited in claim 1 including
brake means having an open center disc,
internal caliper means having compound application characteristics in
forward and reverse driving modes,
said internal caliper means including double-ended brake shoe supports,
a plurality of hydraulic cells for actuating said caliper means to bear
against said disc in normal braking modes, and
a plurality of elliptically-shaped cams for engaging said caliper means in
emergency braking and parking.
20. The motor recited in claim 1 including,
programmable control means which includes read-only memory (ROM) means,
current source means,
said ROM includes a plurality of address lines to which current is supplied
from said current source and,
buffer means connected to supply signals to said plurality of
electromagnets,
said ROM includes a plurality of output lines connected to said buffer
means.
21. The motor recited in claim 20 including,
photon-coupled isolators connected to said buffer means to control the
application of signals to said electromagnets.
22. The motor recited in claim 1 including
controller means,
power conversion means connected to said controller means and to said
electromagnets,
brake circuit means connected to said electromagnets,
mode selection means connected to said controller means, and
speed control means connected to said controller means.
23. The motor recited in claim 22 including
Hall effect sensors associated with said permanent magnets and connected to
supply signals to said controller means, and
phase control means connected between said speed control means and said
power conversion means.
24. The motor recited in claim 23 including
source means, and
regenerative braking means connected between said electromagnets and said
source means,
said source means connected to supply signals to said power conversion
means.
25. The motor recited in claim 1 wherein, said stator means is mounted to
be stationary on suitable axle means, and
said rotor means is mounted on suitable bearings to rotate around said axle
means.
26. The motor recited in claim 1 wherein,
the number of permanent magnets included in said rotor means is larger than
the number of electromagnets included in said stator means.
27. The motor recited in claim 1 wherein,
said permanent magnets include rare-earth materials in the cores thereof.
28. The motor recited in claim 1 wherein,
said permanent magnets have cores in which the central core portion is
thicker than the end pole pieces.
29. A control circuit comprising:
power conversion circuitry;
said power conversion circuitry comprising,
a plurality of inverter rectifiers of the controlled type;
a plurality of fast recovery rectifiers connected in parallel with
respective inverter rectifiers; and
reactive means connected between the parallel connected networks formed by
said inverter rectifiers and said fast recovery rectifiers;
brushless commutation circuitry connected to said power conversion
circuitry; p1 polyphase rectification circuitry;
said brushless commutation circuitry and said polyphase rectification
circuitry each comprising gate controlled rectifiers;
said brushless commutation circuitry and said polyphase rectification
circuitry being mutually exclusively operable;
inductive windings connected to said brushless commutation circuitry and to
said polyphase rectification circuitry;
programmed controller means connected to said brushless commutation
circuitry and to said polyphase rectification circuitry to control the
operation thereof; and
source means connected in said power conversion circuitry;
said brushless commutation circuitry connecting said power conversion
circuitry to said inductive windings to supply energy to said inductive
windings;
said polyphase rectification circuitry connected by said inductive windings
to said power source to return energy to said power source.
30. The control circuit recited in claim 29 including:
full wave phase control means connected between said power conversion
circuitry and said inductive windings to control the signal waveform at
said inductive windings.
31. The control circuit recited in claim 29 wherein:
said programmed controller means includes read only memory means (ROM)
which permits the programmed controller means to be programmed for forward
or reverse operation.
32. The control circuit recited in claim 31 including:
switch means connected to supply information to said ROM.
33. The control circuit recited in claim 32 wherein:
said switch means comprise Hall effect digital switches.
34. The control circuit recited in claim 32 including:
manual control switches for controlling direction and speed of operation as
a function of the circuit operation. |
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Claims |
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Description |
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BACKGROUND
1. Field of the Invention
This invention is directed at a prime mover, in general, and to a
self-contained electro-magnetically driven power wheel, in particular.
2. Prior Art
Modern man relies extremely heavily on motorized vehicles for
transportation. For individual movement, man relies nearly as heavily upon
land based motorized vehicles. Primary among such vehicles is the
automobile. However, conventional automobiles are now becoming a severe
problem. For example, increasing costs and diminishing supplies of fossil
fuels, the public's growing concern and awareness of the problem of air
pollution and, to a lesser extent, the problem of noise pollution, have
motivated inventors to search for a practical alternative to the internal
combustion engine as a means of motive power for vehicles.
In the past, alternatives such as steam driven vehicles have been tried and
discarded as impractical. More recently, electric cars have been viewed as
a viable alternative.
Resistive motor speed controls, especially common to golf carts and the
like, have been used. These controls operate smoothly, though
inefficiently, at all but maximum speed. More recently, pulse-width
modulation techniques in designs employing high-current Darlington
transistors have been limited to the control of low-horsepower motors.
These controls are load sensitive and operate at a frequency which tends
to resonate field laminations of electric motors, thus producing an
audible whining sound as well as having other objectionable
characteristics.
In addition, alternative power sources have other drawbacks for use in
vehicular applications. For example, battery operated vehicles have
suffered from short range, low speed, and excessive weight. Also, recharge
requirements impose long down-time periods. These shortcomings must be
overcome before an electric vehicle becomes a viable alternative.
SUMMARY OF THE INVENTION
A compact, electric motor is provided. The motor is self-contained within a
wheel unit so that a drive element is established. The motor provides a
plurality of permanent magnets which interact, in a controlled manner,
with electromagnets. A microprogrammed controller permits the magnets to
interact in a manner to provide forward or reverse motion as well as a
neutral position. In addition, electrical braking can be accomplished. The
motor/wheel unit can be utilized with any suitable vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cut away, cross-sectional view of the invention in a typical
wheel configuration.
FIG. 2 is a partially broken-away plan view of the permanent magnet
configuration for one-half of the rotating motor housing with stationary
electromagnetic poles superimposed thereon.
FIG. 3 is a partial cross-sectional view of the stator electro-magnets and
the rotor permanent magnets.
FIG. 4 is a plan view of the brake mechanism for the instant invention.
FIG. 4A is a detailed showing of a portion of the brake mechanism shown in
FIG. 4.
FIG. 5 is a cross-sectional view of the combination hydraulic and
mechanical brake mechanism as shown in FIG. 4.
FIGS. 6A and 6B are alternative permanent magnet configurations using
linear magnetic elements with added pole pieces.
FIG. 7 is a block diagram of the magnetic and electronic hardware
configuration of the instant invention.
FIG. 8 is a schematic diagram of the power conversion circuitry with
commutation and polyphase rectification provisions.
FIG. 9 is a schematic diagram of the basic microprogrammed controller.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to FIG. 1, there is shown a cut away, cross-sectional view of
a typical motor and a cross-section of the wheel within which it can be
contained in accordance with the instant invention. The stationary shaft 1
of the motor is attached to a suitable suspension structure 40 which will
not be described in detail. However, suspension structure 40 is provided
with an axial opening (or channel) suitable for carrying power lines 25
and 26, and shielded control lines in multiple conductor cable 27. These
lines pass through fixed axle 1 via a plurality of passages 41 and a
common axial duct 42. In addition, passages 41 can also be utilized by
coolant lines 19 if required in higher power versions of the motor. In the
case of front suspension, the base of a McPhearson strut is attached to
the axle using a similar pattern of machine bolts 52. The power leads 25
and 26 and the control lines 27, as well as coolant tubes 17 and 18 exit
axially and loop in extra flexible connections, not shown.
Fixed upon shaft 1 is stator web 2 upon which a plurality of stator field
support arms 3 are radially mounted by machine screws 32 or other suitable
fasteners. In this embodiment, twelve stator field poles are provided,
each having a support arm 3 which is preferably made of a non-magnetic
material such as stainless steel. Mounted on each support arm 3 are two
highly permeable, magnetic, C-core sections 4 and 5 which are affixed in a
suitable manner, such as by epoxy and reinforced binding materials. The
C-cores are, thus, back-to-back and axially disposed, as well as parallel
to stationary shaft 1.
Each of the stator field poles is wound in a radially-oriented,
multi-layered helix or coil 6 which encompasses both of the C-core
segments 4 and 5 with one continuous winding. Since each of the twelve
electromagnetic field poles in this embodiment of the power wheel occupies
most of a pie-shaped volume of about thirty degrees, some of the outer
layers of the coil wires may be shaped into a wedge (as shown in FIG. 2)
to conform to adjacent field pole windings.
The magnetic flux field which is induced in C-core segments 4 and 5, when
current passes through winding 6, is divided or split into two
axially-directed, symmetrical flux paths emerging on opposite sides of the
coil.
In accordance with the invention, two sets of permanent magnet rotor poles
7 and 8 are arranged in dual annular rings to interact with the
electromagnetic poles of cores 4 and 5. In this embodiment, each set of
permanent magnets 7 and 8 includes twenty-two radially disposed, U-shaped
magnets. The plane of rotation of the permanent magnet pole surfaces is
established at an optimized gap spacing relative to the fixed
electromagnetic poles 4 and 5. The gap spacing is determined by
establishing the minimum spacing commensurate with the axial displacement
freedom of the tapered roller bearings 15 and 16 under the normal pre-load
operating conditions.
Molded into the outer motor shell 9, or fastened to it by suitable rivets
or other fasteners, are six wheel-rim mounting studs 14 upon each of which
is threaded wheel retainer nut 13. The retainer nuts 13 securely hold the
specially formed spider 11 which is appropriately welded to the wheel rim
12 upon which a pneumatic tire 20 is mounted. Shell 10 is joined to shell
9 by means of machine screws 30 to form a complete housing for the wheel
apparatus.
Brake disc 29, described in greater detail relative to FIGS. 4 and 5, is an
open-center annular ring, supported around its periphery by a plurality of
machine screws 31 threaded into motor housing shell 10. Disc 29 is acted
upon by a set of movable, double-ended caliper shoes 35 and 38 and the
corresponding brake pads 33 and 34, when expansion cells 37 and/or 39 are
inflated, for example, hydraulically. Coupling studs 36 transmit the
gripping action between the inner and outer caliper shoes. The caliper
assembly is supported by flange 51 which is an extension of suspension
structure 40. The axle and stator assembly are attached to suspension
structure 40 by a plurality of mounting bolts 52.
In the event continuous high power is required, as in climbing a long
upgrade, cooling coils 19 can be used to cool electromagnetic coils 6 and
cores 4 and 5, as well as electronic modules 53 and 54. The coolant is
circulated via tubes 17 and 18 through structure 40, through hollow axle
passage 42 and duct 41, to cooling coils 19, and back through a similar
path to a suitable cooling radiator assembly (not shown). A fan (not
shown) may be used to cool the radiator with the fan motor also being used
to drive a circulating pump. In addition, fins 49 are provided, e.g. by
molding, at the surface of motor housing 10 for providing cooling. The
cooling can be provided by circulation of a coolant (e.g. air) or
radiation of thermal energy.
Mounted upon stationary central axle 1, in annular compartments on either
side of stator web 2 and field pole support arms 3, are electronic modules
53 and 54 which contain the dual functioning silicon-controlled rectifiers
and microprogrammed controller, described in detail infra. These
electronic circuits respond to Hall effect devices which are mounted
within flux concentrator assemblies 55.
Outer shell 9 is rotatably supported by a set of tapered roller bearings
15. Lubricant for the bearings is retained within rotary seals 21 and 22,
riding on seal seats 47 and 48, respectively. The seals and seats also
serve to exclude, as much as possible, dirt and foreign particles which
would subject the bearings to unnecessary wear.
Inboard permanent magnets 8 (in this embodiment twenty-two permanent
magnets are used) are likewise attached to inner housing shell 10 by
suitable potting adhesives or the like. Inner shell 10 is securely
fastened to outer housing shell 9 by machine screws 30 and is rotatably
supported on a tapered roller bearing set 16 which is held stationary on
non-rotating axle 1 by a selected thickness combination seal seat and
spacing washer 45. Washer 45 establishes the optimum air gap between the
pole surfaces of inner permanent magnets 8 and the end surfaces of C-core
segments 5. The inner hub of stator support spider 2 is retained in place
during assembly, in particular, and during its operating life by retainer
nut 44 which is threaded onto shaft 1. Bearing seals 23 and 24 provide
both lubrication retention and foreign particle exclusion for bearing set
16. Seals 23 and 24 ride on seal seats 43 and 45, respectively (see also
FIG. 5).
Another selected-thickness seal seat and spacing washer 48 establishes
bearing pre-loads while also limiting the space between the fixed inner
race cone of bearings 15 and 16 so that the optimum air gap between outer
permanent magnets 7 and C-core segments 4 of the electromagnetic field
poles can be maintained. The inner race cone of the outer bearing 15 is
pressed inward by the outer seal seat 48 and an outer seal washer and
wheel retaining nut 28.
Solid state commutation of electromagnetic poles 4 and 5 occurs in six
distinct phase relationships (as described infra) that produce magnetic
fields which interact with the twenty-two rotating permanent magnets 7 and
8 to provide a total of 132 steps per revolution of the power wheel. In
general, the number of steps per revolution is given by the product of the
total number of phases and the total number of permanent magnets.
Corresponding poles of each set of permanent magnets 7 and 8 have like
poles facing each other. Additionally, each successive magnet of a set
must have its north and south poles arranged radially and alternately
inward and outward. There is preferably an even number of permanent poles
in each set. The twenty-two outboard permanent magnets 7 are attached to
the outer motor housing shell 9 and are each held in place by suitable
potting adhesives. Placement of the electromagnetic poles and the
corresponding permanent magnet poles at the maximum attainable radial
distance, provides the maximum torque or moment arm for the motor.
Referring now to FIG. 2, there is shown a partially broken-away view of the
arrangement of the various magnets. In particular, FIG. 2 shows twenty-two
permanent U-shaped magnets 8 arranged substantially equidistant from
central shaft 1. It is seen that magnets 8 are arranged in alternating
pole alignment. That is, alternate magnets 8 have north poles adjacent to
south poles of the adjacent magnets. In addition, six (out of twelve)
electromagnetic cores 4 and, thus, cores 5 are superimposed over permanent
magnets 8. Cores 4 are supported by support arms 3 as described supra.
Coils 6 are wound around cores 4 and 5 as noted. In addition, coils 6 tend
to substantially fill the space between cores 4 and 5. Most importantly,
FIG. 2 shows the overlapping arrangement of cores 4 and 5 relative to
magnets 8. This overlapping arrangement assures improved operation of the
invention.
Referring now to FIG. 3, there is shown a cross-sectional view of the
arrangement of the magnets. Permanent magnets 7 and 8 form the outer and
inner rotor poles, respectively. The alternating arrangement of north and
south pole alignment for magnets 7 and 8 is depicted. Likewise, the
alignment of cores 4 and 5 as well as the respective mutual coil 6 is
illustrated. The overlapping arrangement of cores 4 and 5 relative to
permanent magnets 7 and 8, respectively, is clear. In addition, the
support arm 3 is clearly shown with respect to cores 4 and 5 as well as
the mutual coil 6.
Reference is made concurrently to FIGS. 4 and 5. FIG. 4 is a partially
broken-away plan view of the brake mechanism as associated with the
instant invention. FIG. 5 is a cut away view of the brake mechanism shown
from the inboard side of the trailing arm suspension in a typical rear
wheel installation on an electric vehicle taken along the lines 5--5 in
FIG. 4. Both hydraulically and mechanically actuated brakes are provided
by the combination open center disc assembly 29 shown in FIGS. 4 and 5. In
the case of front wheel suspension systems, trailing arm 40 would be
replaced by the piston end of a commonly used McPhearson strut as
suggested by dashed line 64.
Brake disc 29 is rigidly mounted to inboard motor shell 10 by a plurality
of machine screws 31. The remaining brake assembly components are
suspended from substantially disc-shaped extension 61 of trailing arm
assembly 40 which is rigidly attached to non-rotating axle 1 by a
plurality of machine screws 52.
Sandwiched between two substantially semi-circular reactor plates 35 and 58
are two semi-circular diaphragms 37 and 39 made of a suitable material,
such as a synthetic rubber or silicon compound capable of withstanding the
maximum temperatures anticipated to be generated in the application of the
brakes. In a preferred embodiment, hydraulic fluid is supplied to both
diaphragms simultaneously through fitting 59 which is affixed to
stationary support extension 51. Upon actuation of hydraulic braking,
fluid causes diaphragms 37 and 39 to expand thereby forcing the
semi-circular brake shoe 35 outwardly toward disc 29 and causing brake pad
34 to engage the inboard surface of disc 29. Simultaneously, the expansion
of diaphragm 39 causes reactor plate 58 to move away from extension 51.
The four pull-rods 36, which are attached to semi-circular brake shoe 38,
are moved thereby causing brake pads 33 to engage the outboard surface of
brake disc 29. Upon release of the hydraulic pressure, three compression
springs 63 force the brake shoes apart so that disc 29 can again turn
freely.
Because it is required by law to provide emergency braking capability and
the additional need for parking brakes, provision is made for mechanical
actuation of the brakes by a parking brake lever and known systems of
cabling. Referring to FIG. 4 and the detail of FIG. 4A there are shown the
unique components of the parking brake system. Between each of the two
pairs of pull-rods 36, is a cam 60 which is affixed to actuator rod 61.
Each cam is captivated by the respective cutout 60A shown in plate 51 and
by reactor plates 35 and 58. The reactor plates are forced toward each
other (and away from disc 29) by brake shoe separator springs 63. When
drag link 62 is moved in the direction of arrow 62A, cam 60 causes reactor
plates 35 and 58 to separate in the same manner as when the hydraulic
diaphragms 37 and 39 are pressurized, thereby causing the application of
brake pads 33 and 49 against brake disc 29.
It can be seen that the two cams can be rotated by two short drag links 62
which have their other ends attached to a double bell crank (not shown) of
known configuration pivoted on the axis of the main axle, or in any number
of simple linkages and flexible cable arrangements that can be actuated by
application of a typical parking or emergency brake lever or pedal.
FIGS. 6A and 6B show two views each of alternative configurations of the
permanent magnets 7 or 8 (see FIGS. 1-3) which offer certain advantages in
the invention. FIG. 6A shows details of Hall effect sensor 55A and flux
concentrator poles 55B. Partially broken-away views of adjacent magnets
are included to show the physical relationships needed for proper
commutation as the magnetic poles move in either direction, forward or
reverse, as depicted by the double-ended arrow, while the assembly 55
remains stationary. The cross-sectioned areas 55C represent sections
through non-magnetic clamp material.
The magnet of FIG. 6A is much thicker in the curved section than U-shaped
permanent magnets 7 and 8 in earlier figures. This alternative provides
appreciable gain in total flux and retentivity using materials such as
Alnico V.
In FIG. 6B, an alternative composite version is shown wherein a linear or
grain-oriented magnetic material such as Alnico 8 or 9, or a rare-earth
ceramic such as Samarium-Cobalt is used in portion 7A of the magnet. Pole
pieces 7B and 7C are highly permeable material such as cast iron or Armco
magnetic iron. Leakage flux shunting strap 7D is also a highly permeable
ribbon. Block 7E can be non-magnetic aluminum, plastic filler or the like
which serves to keep the basic form factor, if interchangability of
magnetic cores is deemed desirable.
FIG. 7 is a block diagram of the magnetic and electronic hardware
configuration, wherein the dotted lines indicate magnetic field couplings
and the solid lines indicate electrical connections. The configuration
shows the arrangement of components, the general flow of power and control
signals, and primary functions of the invention. Thus, power conversion
circuitry 200, consisting of a high-frequency inverter, is connected to
brushless commutation circuitry 201, which, in turn, is connected to
electromagnetic field poles 5. This sequential path is applicable during
motor operation of the invention. During generator operation, the voltage
induced in electromagnetic field poles 5 is supplied to polyphase
rectification circuitry 206, which, in turn, is connected to regenerative
braking circuitry 205. Positive and negative switching regulators,
included in the regenerative braking circuitry 205, return power to
batteries 65. Optional motor/generator 208 of any known configuration is
also connected to batteries 65.
The bi-directional path in FIG. 7, indicated by the two arrows between
electromagnetic field poles 5 and brushless commutation/polyphase
rectification unit 207, illustrates that the individual functions of
brushless commutation circuitry 201 and polyphase rectification circuitry
206 are both implemented using a single electronic configuration that
satisfies the dual motor/generator operating requirements. Likewise, a
single phase control unit 202 is connected to brushless
commutation/polyphase rectification unit 207 to adjust both the degree of
acceleration and braking of the invention in response to user-operated
accelerator 204 and user-operated brake 203, respectively.
Entirely within the wheel housing is microprogrammed controller 209 which
receives input signals from user-operated forward, neutral, and reverse
selector switch 93, user-operated brake 203, and Hall effect devices 91.
Controller 209 supplies control signals to photon-coupled isolators 98,
which, in turn, control brushless commutation/polyphase rectification unit
207. The commutation/polyphase rectification unit 207 consists of
dual-functioning silicon-controlled rectifiers. Permanent magnets 7, 8
which influence the output states of Hall effect devices 91 and interact
with electromagnetic poles 5 are also shown.
The power conversion circuitry 200 and brushless commutation/polyphase
rectification circuitry 207 are illustrated in greater detail in the
schematic diagram of FIG. 8. A plurality, for example sixteen, six-volt,
deep discharge batteries 65 are connected in series. Of course, improved
lead-acid batteries, other chemical batteries, or futuristic power sources
with greater kilowatt-per-pound capability are contemplated for use with
the design to provide greater range capability of a vehicle equipped with
this invention.
The power inverter circuitry 200 consists of two inverter
silicon-controlled rectifiers 66 and 67, two fast-recovery rectifiers 68
and 69, and commutation capacitor 72. A properly chosen resistor-capacitor
snubber network (not shown) can be connected across each SCR 66 and 67 to
minimize ringing and suppress voltage transients. Fast recovery rectifiers
68 and 69 aide in minimizing radio-frequency-interference generated by the
inverter circuitry, and provide current return paths to batteries 65
during reverse current flow when turn-off time is cyclically presented to
silicon-controlled rectifiers 66 and 67, respectively. Inductors 70 and 71
are each wound on separate molybdenum or other suitable high permeability
cores.
The upper limit on the high-frequency operation of the inverter, which
contributes compactness and efficiency of the circuitry, is limited by the
turn-off time parameters associated with inverter SCRs 66 and 67, and the
load impedance characteristics of the electromagnetic field pole windings
6.
Capacitor 73 is connected in series with the invertr load and serves a
current limiting function during the peak current flow associated with the
particularly high starting torque of the invention.
In the embodiment shown in FIG. 8, the inverter circuitry is directly
coupled (not transformer coupled) to the electromagnetic field pole
windings 6. Thus, the inverter load is represented as the average combined
impedance of the electromagnetic pole pair windings. This specific
configuration takes advantage of the inherent characteristic of the
inverter to operate effectively into varying inductive loads. In addition,
the inherent power losses that are characteristic of transformer coupled
configurations are obviated.
During motor operation of the invention, the high-frequency AC output
signal of the inverter is full-wave phase controlled in a known fashion
through SCRs 76 and 77. Meanwhile SCRs 74 and 75 are triggered into full
conduction and SCRs 81 and 82 remain in the non-conducting (blocking)
state. During generator operation of the invention, SCRs 74 and 75 are
placed in the blocking state, thus completely isolating the inverter
output from electromagnetic field pole pair windings 6. The six-phase
voltage waveform induced in the electromagnetic pole pair windings 6 is
full-wave, phase controlled through SCRs 76 and 77 and returned to
batteries 65 via SCRs 81 and 82 which are triggered into full conduction,
thus effecting regenerative braking. Since the generated voltage may be
insufficient to effect regenerative braking, a mechanical friction brake
supplements the braking process, particularly at slow vehicle speeds and
for parking as described supra. In a known fashion, conventional schemes
can be employed for paralleling series connected batteries 65 to
accommodate regenerative braking at lower vehicle speeds and thus, lower
generator output voltages. However, in the preferred embodiment of the
regenerative braking circuitry, the use of positive and negative switching
regulators (not shown) provide a constant output over a wide variation in
input voltage. The positive and negative switching regulators
simultaneously charge all series connected batteries and at the same time
eliminate the plurality of mechanical, high-current, DC switches required
by other battery-paralleling schemes.
In accordance with the invention, commutation of the electromagnetic field
poles 6, is achieved utilizing a cyclo-inverter waveform consisting of a
high-frequency, full-wave, phase-controlled, AC voltage, modulated by the
comparatively slower switching frequency of Hall effect sensors 55 in the
microprogrammed controller circuitry shown in detail in FIG. 9. The
electromagnetic field pole windings 6 are switched by the matrix
connection of SCR pairs 78 and 79. Rotational torque is thus achieved by
directing current flow through each independently controlled
electromagnetic field pole pair winding in such a manner as to produce a
magnetic field which attracts the closest approaching permanent magnet on
the rotor, and likewise, repels the adjacent departing permanent magnet.
Torque developed by the power wheel is a function of the magnitude of the
magnetic flux field and the effective magnitude of the electromagnetic
field pole current.
Also in accordance with the invention, an emergency stop can be implemented
by utilizing a principle, herein referred to as counter magnetic field
braking. An emergency braking condition can be determined in a known
fashion by sensing the rate of change in the application of the
user-operated brake pedal. In an emergency stop, SCRs 81 and 82 revert to
a blocking state and power is immediately phase controlled and applied to
the electromagnetic field pole pair windings 6. While the vehicle is
traveling in a forward direction, however, the electromagnetic pole pairs
are commutated as if in the reverse mode. The resulting counter
electromagnetic field produced attempts to reverse the rotation of the
wheel. Counter magnetic field braking is possible due to the unique
magnetic drive coupling of the invention and the complete absence of
mechanical drive interfaces.
FIG. 9 is a detailed schematic diagram of a preferred embodiment of
microprogrammed controller 209. Controller 209 employs six single-ended,
three-terminal Hall effect devices 91. Each Hall effect device is mounted
on a flux concentrator assembly 55 (see FIG. 6A). Source current is
supplied to read-only memory 95 (ROM) address lines A.sub.0 through
A.sub.7 via eight pull-up resistors 92. Single-pole, triple-throw switch
93 selects forward, neutral, or reverse operating modes, while
single-pole, single-throw switch 94 enables polyphase rectification for
regenerative braking. Switches 93 and 94 are both user-operated and are
the only components in FIG. 9 which are external to wheel housing 9, 10.
The output lines O.sub.1 through O.sub.6 of ROM 95 are connected to
directly drive the inputs of hex inverter buffer 96 and hex buffer 97,
which in turn, drive optoelectronic devices, such as infrared emitting
diodes (IREDs) 101 within the photon-coupled isolators 98. The matrix
connection between the output lines of ROM 95 and the input lines of hex
inverter buffer 96 and hex buffer 97, ensures that exactly six of the
twelve buffer output lines will be low at any given instant. Thus,
specification of resistor 99 is based upon the continuous current
requirements of six IREDs. Each light-activated silicon-controlled
rectifier (LASCR) 102 within the photon-coupled isolators 98 controls the
similarly oriented power SCR 78, 79 in the schematic diagram of FIG. 8. A
resistor which determines the input current to trigger, is typically
connected between the gate and cathode of each LASCR 102. Also, a series
current-limiting resistor (not shown) is typically connected between the
anode of each power SCR in FIG. 8 and the anode of the similarly oriented
LASCR in FIG. 9. The cathode of each LASCR 102 is connected to the gate of
the similarly oriented power SCR, thus providing a sensitive gate trigger
which commutates the controlled power SCR "on" each time the corresponding
IRED 101 is forward biased.
Microprogrammed controller 209, in accordance with the invention, performs
five controlling functions: brushless commutation of the motor in both
forward and reverse modes; polyphase rectification of the generator in
both forward and reverse modes; and neutral. Since both the neutral
function and forward polyphase rectification function produce identical
ROM outputs in the electronic circuitry of FIG. 9, only four distinct
functions are actually realized. These four functions are implemented
through utilization of a 2048-bit, custom-masked, bipolar ROM (256.times.8
bit ROM), depicted as ROM 95 in FIG. 9. In general, microprogrammed ROM 95
requires a minimum number of addressable words given by
m.multidot.2.sup.n, where m is the number of distinct control functions
and n is the number of phases.
Table I contains the 256 addressable words and corresponding eight-bit,
binary output codes which define the custom ROM mask. The output bits are
read from right to left in Table I and correspond to ROM output lines
O.sub.1 through O.sub.8 in FIG. 9. Commutation of the six electromagnetic
pole pairs is influenced only by output lines O.sub.1 through O.sub.6.
Since output lines O.sub.7 and O.sub.8 are not utilized, they have been
arbitrarily set to "1". Thus, each output in the table is of the form
"11XXXXXX". However, of course, any size ROM can be used if other
functions are desired. In addition, a different ROM mask can be
established if desired.
Words 0 through 63 accommodate regenerative braking commutation of the
invention when operating as a generator in the reverse mode; words 64
through 127 accommodate both the neutral mode and regenerative braking
commutation of the invention when operating as a generator in the forward
mode; words 128 through 191 and words 192 through 255 accommodate
commutation of the invention when operating as a motor in the reverse and
forward modes, respectively.
Six hall effect devices 91 and two switches 93, 94 shown in FIG. 9 supply
the eight-bit word address information to ROM 95. The output bits
corresponding to words 0 through 127 and words 128 through 256 are derived
from the analysis of the six-phase voltage waveform generated by the
invention, and the six-phase cyclo-inverter waveform supplied to the
electromagnetic field poles of the invention, respectively.
Thus, there has been shown and described an electronically driven wheel
which is substantially independent of external components. The wheel
operates in forward, reverse, or neutral modes. The wheel is the motor
with microprogrammed controller and dual-functioning
commutation/rectification circuitry contained entirely within a wheel.
TABLE 1
__________________________________________________________________________
WORD OUTPUT
WORD OUTPUT
WORD OUTPUT
WORD OUTPUT
__________________________________________________________________________
0 11000000
64 11111111
128 11111111
192 11000000
1 11001000
65 11110111
129 11111110
193 11000001
2 11010000
66 11101111
130 11111101
194 11000010
3 11011000
67 11100111
131 11111100
195 11000011
4 11100000
68 11011111
132 11111011
196 11000100
5 11101000
69 11010111
133 11111010
197 11000101
6 11110000
70 11001111
134 11111001
198 11000110
7 11111000
71 11000111
135 11111000
199 11000111
8 11000001
72 11111110
136 11110111
200 11001000
9 11001001
73 11110110
137 11110110
201 11001001
10 11010001
74 11101110
138 11110101
202 11001010
11 11011001
75 11100110
139 11110100
203 11001011
12 11100001
76 11011110
140 11110011
204 11001100
13 11101001
77 11010110
141 11110010
205 11001101
14 11110001
78 11001110
142 11110001
206 11001110
15 11111001
79 11000110
143 11110000
207 11001111
16 11000010
80 11111101
144 11101111
208 11010000
17 11001010
81 11110101
145 11101110
209 11010001
18 11010010
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