Home News Headlines News Blog Links Tesla Roadster Nikola Tesla Biography Tesla Flying Machine A Simple magnetic motor Electric Cars Electric Motors Generators and Alternators Historical Super Carburetors Books on Super Carbs Mighty Yet Tiny engine, NASA 1st prize H.J. Magnet Motor Future Denied The Pacheco Hydrogen Generator A Hydrogen Generator you can build many more Hydrogen Generators others have built Dennis Lee Energy Inventions (suppressed) Hydraulic cars & info Mike Blood's Hydraulic dragster 1997 Don Banky's Hydraulic Car 1955 I.V.T. / C.V.T. Oil News

ELECTRIC MOTORS

to understand the differences and the issues

The most commonly used motors in EV conversions are series wound DC motors. Most new parts suppliers carry the Advanced DC or Warp lines of motors. There are also quite a few folks using older General Electric, Baldor, and Prestolite motors. Many older conversions were based on surplus starter/generators. While these are still available, they are difficult to mount, inefficient, and generally incompatible with modern controllers. A conversion based on one of these might be functional, but it would ultimately be disappointing. There are a few decent surplus motors available from time to time. Forklift and elevator motors are usually much to heavy to use, while golf cart motors are too small. Recently, AC drive motors have become available, and it is likely that more conversions will be using them.

Another possibility:

Examples John Wayland's White Zombie 0 to 60 in ~3.5 sec's. 1/4 mi in 11.466 sec's. @ 114.08 mph Powered by dual 8 in.(”Siamese 8″) Warfield Dual armature series-wound motors for 240+ hp w/ 772 ft. lbs. torque. read more about it The Quickest electric motorcycle: the KillaCycle the KillaCycle team In Nov 2007, the KillaCycle made a quarter-mile run in 7.824 seconds and hit 168 mph it weighs about 600 lbs. It has two modified 6.7 inch Model L-91 Advanced DC Motors The battery pack has/had a total of 990 A123 Systems M1 Li-Ion cells with a total weight of 180 lbs. read more about it

Strength of an electromagnetic field

The strength of the electromagnetic field is determined by the amount of current, number of coils of wire, and the distance from the wire.

Unit

The unit of magnetic force is called the tesla (T). Near a strong magnet the force is 1-T. Another unit used is the gauss, where 10⁴ gauss (10,000) equals 1 tesla.

Current

The strength of the magnetic field is proportional to the current in the wire. If you double the current, the magnetic force is doubled.
Since Voltage = Current x Resistance (V = I*R), you can double the current in a wire by doubling the voltage of the source of electricity.

Turns of coil

If you wrap the wire into a coil, you increase the magnetic force inside the coil, proportional to the number of turns. In other words, a coil consisting of 10 loops has 10 times the magnetic force as the wire uncoiled, with the same current flowing through it. Likewise, a coil of 20 loops has 2 times the magnetic force than one with 10 loops.

Varies with distance

The magnetic force decreases with distance. It decreases proportionally to the square of the distance. For example the force at 2 cm. from a wire is 1/4 that of at 1 cm., and the force at 3 cm. is 1/9 the force at 1 cm.

Effect of an iron core

When the coil is wrapped around an iron core, the strength of the electromagnetic field is much greater than the same coil without the iron core. This is because the atoms in the iron line up to amplify the magnetic effect. The orientation of the atoms in the iron is called its domain.

Current

When you increase the current, the magnetic strength increases, but it is not exactly linear as it is with the coil by itself. The characteristics of the core cause the curve of magnetic strength versus current to be an s-shaped hysteresis curve.
The shape of this curve depends on how well the material in the core becomes magnetized and how long it remains magnetized. Soft iron loses its magnetism readily, while hard steel tends to retain its magnetism.

Inductance

Inductance (measured in henries) is an effect which results from the magnetic field that forms around a current carrying conductor. Electrical current through the conductor creates a magnetic flux proportional to the current. A change in this current creates a change in magnetic flux that, in turn, generates an electromotive force (emf) that acts to oppose this change in current. Inductance is a measure of the generated emf for a unit change in current. For example, an inductor with an inductance of 1 henry produces an emf of 1 V when the current through the inductor changes at the rate of 1 ampere per second. The inductance of a conductor is increased by coiling the conductor such that the magnetic flux encloses (links) all of the coils (turns). Additionally, the magnetic flux linking these turns can be increased by coiling the conductor around a material with a high permeability.

The energy (measured in joules, in SI) stored by an inductor is equal to the amount of work required to establish the current flowing through the inductor, and therefore the magnetic field.

An inductor is usually constructed as a coil of conducting material, typically copper wire, wrapped around a core either of air or of ferromagnetic material. Core materials with a higher permeability than air confine the magnetic field closely to the inductor, thereby increasing the inductance. Inductors come in many shapes. Most are constructed as enamel coated wire wrapped around a ferrite bobbin with wire exposed on the outside, while some enclose the wire completely in ferrite and are called "shielded". Some inductors have an adjustable core, which enables changing of the inductance. Inductors used to block very high frequencies are sometimes made with a wire passing through a ferrite cylinder or bead.

Inductors are used extensively in analog circuits and signal processing. Inductors in conjunction with capacitors and other components form tuned circuits which can emphasize or filter out specific signal frequencies. Small inductances generated by a ferrite bead or torus around a cable prevent radio frequency interference from being transmitted down the wire. Smaller inductor/capacitor combinations provide tuned circuits used in radio reception and broadcasting, for instance.

Two (or more) inductors which have coupled magnetic flux form a transformer, which is a fundamental component of every electric utility power grid. The efficiency of a transformer increases as the frequency increases; for this reason, aircraft used 400 hertz alternating current rather than the usual 50 or 60 hertz, allowing a great savings in weight from the use of smaller transformers.

An inductor is used as the energy storage device in a switched-mode power supply. The inductor is energized for a specific fraction of the regulator's switching frequency, and de-energized for the remainder of the cycle. This energy transfer ratio determines the input-voltage to output-voltage ratio. This XL is used in complement with an active semiconductor device to maintain very accurate voltage control.

Inductors are also employed in electrical transmission systems, where they are used to intentionally depress system voltages or limit fault current. In this field, they are more commonly referred to as reactors.

As inductors tend to be larger and heavier than other components, their use has been reduced in modern equipment; solid state switching power supplies eliminate large transformers, for instance, and circuits are designed to use only small inductors, if any; larger values are simulated by use of gyrator circuits.

capacitor

While an inductor opposes changes in current, a capacitor opposes changes in voltage.

Imagine an electric car with the same acceleration capability as a gas-powered sports car, or ultrafast rechargeable “batteries” that can be recharged a thousand times more than existing conventional batteries. According to physicists at North Carolina State University, all of these things are possible, thanks to their research on a polymer - or plastic material - that when used as a dielectric in capacitors may allow the capacitors to store up to seven times more energy than those currently in use.

see the news: advancements in batteries and capacitors

Capacitor start motor

In a capacitor start motor, a starting capacitor is inserted in series with the startup winding, creating an LC circuit which is capable of a much greater phase shift (and so, a much greater starting torque). The capacitor naturally adds expense to such motors.

Permanent split-capacitor motor

Another variation is the Permanent Split-Capacitor (PSC) motor (also known as a capacitor start and run motor). This motor operates similarly to the capacitor-start motor described above, but there is no centrifugal starting switch and the second winding is permanently connected to the power source. PSC motors are frequently used in air handlers, fans, and blowers and other cases where a variable speed is desired. By changing taps on the running winding but keeping the load constant, the motor can be made to run at different speeds. Also provided all 6 winding connections are available separately, a 3 phase motor can be converted to a capacitor start and run motor by commoning two of the windings and connecting the third via a capacitor to act as a start winding.

Stepper motors

Closely related in design to three-phase AC synchronous motors are stepper motors, where an internal rotor containing permanent magnets or a large iron core with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the motor may not rotate continuously; instead, it "steps" from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards.

Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can proportionally control the power to the field windings, allowing the rotors to position "between" the "cog" points and thereby rotate extremely smoothly. Computer controlled stepper motors are one of the most versatile forms of positioning systems, particularly when part of a digital servo-controlled system.

Stepper motors can be rotated to a specific angle with ease, and hence stepper motors are used in pre-gigabyte era computer disk drives, where the precision they offered was adequate for the correct positioning of the read/write head of a hard disk drive. As drive density increased, the precision limitations of stepper motors made them obsolete for hard drives, thus newer hard disk drives use read/write head control systems based on voice coils.

Stepper motors were upscaled to be used in electric vehicles under the term SRM (switched reluctance machine).

Coreless DC motors

Nothing in the design of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate; torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the coreless DC motor, a specialized form of a brush DC motor. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder inside the stator magnets, a basket surrounding the stator magnets, or a flat pancake (possibly formed on a printed wiring board) running between upper and lower stator magnets. The windings are typically stabilized by being impregnated with epoxy resins.

Because the rotor is much lighter in weight (mass) than a conventional rotor formed from copper windings on steel laminations, the rotor can accelerate much more rapidly, often achieving a mechanical time constant under 1 ms. This is especially true if the windings use aluminum rather than the heavier copper. But because there is no metal mass in the rotor to act as a heat sink, even small coreless motors must often be cooled by forced air.

These motors were commonly used to drive the capstan(s) of magnetic tape drives and are still widely used in high-performance servo-controlled systems.

Series Wound DC motor

The distinguishing design of a Series Wound DC motor is that the field windings and the armature are electrically connected in series. Torque and speed control are achieved by a ‘throttle’ that varies the intensity of current flowing through the fields and the armature. Series wound motors offer very high starting torques and good torque output per ampere, but have generally poor speed regulation. DC motors have high torque at low speeds and decreasing torque as the speed increases.

This is how the golf carts were designed for many years. But there are some problems with this design. The largest problem was the ‘Free Wheeling’ nature of this system when the golf cart goes down hill. The only thing to keep the golf cart from going dangerously fast (if the hill is steep enough) is to use the Cart’s brakes. As accidents and incidents piled up, golf cart Manufacturing companies became increasingly concerned about creating an electric golf cart that has built in safety features. Enter separately excited field DC Motors.

Separately excited field DC Motors

The separately excited field DC Motors are different from Series Wound DC Motors primarily in the way the field is wound. Series motors create the electromagnetic field using very large wire and a high amperage.

It so happens, however, that you can get the very same flux field with much smaller wire and much less current flow by making many more turns. A field of flux, then, is a function of “Ampere (current)-Turns”.

The difference is very significant! A series wound field has a current of, say, 300 amps. The same separately excited field has a current of only 20 amps. It has been known for a long while that a computer programmed controller could be built to control a 300 amp field, but the components and size would be unacceptable if only from a cost standpoint. The 20 amp current of a separately excited field motor is a different story. A computerized program controller can be designed to provide a wide variety of control over the fields to result in a wide variety of performances. And the most important thing is that it could be built within an acceptable manufacturing cost.

So if a controller can be built to manipulate the electric fields of a DC motor, then we can Control the motor to make it do the things that we want it to do. And from this possibility came all these new innovations to modern day Electric golf carts. Rollaway Protection, downhill Regenerative Braking and Torque/Speed Controls for a wide variety of conditions are now available. The constant implication, of course, is that Safety features can now be created.

Electric Motors The various winding configurations of electric motors have lost much of their significance with the advent of electronic controls. The use of series fields over shunt, of DC power over AC have lost their advantage. Electronic Converters can give a shunt wound motor just as much starting torque as a series wound motor, and can convert AC to DC and back again to optimize voltage, current and frequency for maximum power and efficiency. No matter how much the controls change, the basic fact remains that all electric motors use an alternating current in one or more windings. AC can be used direct, DC can be converted to AC either electronically or mechanically by the use of a commutator and carbon brushes. Traditional mechanical methods are simple and reliable, but cannot be optimal for all load-speed conditions. Electronic methods are often more efficient over a wider range of load-speed conditions, but are expensive and more easily damaged by transient voltages or currents. Another basic fact is that motor torque is proportional to the number of armature amp-turns, armature size, and the strength of the magnetic field around the armature. The magnetic field increases with the amp-turns of the field. The increase is proportional until the magnetic path begins to saturate. The strength of the magnetic field is basically limited by the quality of the magnetic material. The amount of the magnetic field is limited by the area of the magnetic material and heat which limits field current. Armature current is also limited by heat. All small, high power motors require external cooling. Motor power is proportional to torque and speed. One of the biggest advantages of electronic controls is the efficient conversion of power to high frequency AC. Motors with an excess of 400 Horsepower have been built with speeds greater than 20,000 RPM. The ability to put a lot of power is a small space is only available with electronic conversion. Limitations of mechanical commutation limit maximum motor speed. Part of the job of commutation is to "discharge" windings as they leave one pole and head for another. In series wound motors, the location of the brushes is often shifted to optimize one direction of rotation. Large shunt wound motors often employ commutating field windings (aka interpole windings) between the main field windings. These are wired in series with the armature and induce a voltage in the armature to help neutralize the energy in the windings being commutated. Without commutating field windings, the brushes must dissipate this energy and can overheat at high speeds. High speed operation greatly increases brush wear. Shunt Motors The amount of voltage generated by a shunt motor is proportional the magnetic field and motor speed. The speed at which this generated voltage is equal to battery voltage with maximum field current is a critical design parameter in electric vehicle design. This speed is the maximum speed at which full torque is available, and is also the slowest speed at which simple regenerative braking can charge a battery. (Call this regen speed.) Dynamic braking can be used at slower speeds by connecting the armature to a resistive load. Above this speed, the motor is horsepower limited. Of course commutation limitations and mechanical strength limit maximum motor speed. A typical driving cycle would start accelerating a vehicle from a stop with maximum field current, and armature current limited to a safe value. A constant motor torque would give a constant acceleration (neglecting increasing vehicle losses) until regen speed is reached. Above this speed, the armature is connected directly to the battery and armature current is maintained by a field current which decreases with increasing speed until maximum motor speed is reached. Torque decreases with decreasing field current so acceleration also decreases. At maximum speed, field current is increased to decrease armature current and torque as necessary to maintain a constant speed. To slow down, field current is further increased as necessary to cause the motor to reverse armature current and thus charge the battery. The vehicle slows down until maximum field current is reached at regen speed. Below this speed, dynamic breaking can be used to augment mechanical brakes. Note that mechanical brakes must be used in addition to regenerative braking if a fast stop is necessary. Maximum armature current must not be exceeded. As the motor temperature increases, maximum armature and fields currents must be reduced which significantly reduces maximum motor torque. Note all the energy supplied to accelerate the vehicle is not recovered during regenerative breaking. One of the major losses is that a battery is recharged at a higher voltage then it is discharged. (i.e. a 144 volt battery might take 170 volts to charge, but only return 120 volts under load.) Another loss is the motors I2R losses, the heat created by current and resistance in the armature, and the power consumed by the field. To correctly design an electric vehicle, the motor characteristics must be known. For a shunt motor the following questions must be asked: DESIGN VOLTAGE MAXIMUM RPM MAXIMUM TORQUE MAXIMUM OUTPUT POWER MAXIMUM CONTINUOUS OUTPUT POWER MAXIMUM ARMATURE CURRENT MAXIMUM CONTINUOUS ARMATURE CURRENT MAXIMUM FIELD CURRENT MAXIMUM CONTINUOUS FIELD CURRENT BACK EMF PER RPM AT VARIOUS FIELD CURRENTS: (Including maximum and max continuous) TORQUE AS A FUNCTION OF BOTH FIELD & ARMATURE CURRENTS EFFICIENCY AS A FUNCTION OF SPEED AND TORQUE As an example, the following shunt wound motor has been designed: DESIGN BATTERY VOLTAGE 144 volts DESIGN BATTERY RESISTANCE .06 ohm REGEN RPM 3600 rpm MAXIMUM RPM 5000 rpm MAXIMUM CONTINUOUS TORQUE 30 lb - ft MAXIMUM OUTPUT POWER 40 hp MAXIMUM CONTINUOUS OUTPUT POWER 20 hp MAXIMUM ARMATURE CURRENT 250 amps MAXIMUM CONTINUOUS ARMATURE CURRENT 125 amps MAXIMUM FIELD CURRENT 3.5 amps MAXIMUM CONTINUOUS FIELD CURRENT 2.0 amps RESISTANCE OF ARMATURE 0.04 ohm RESISTANCE OF FIELD 40 ohms BACK EMF PER RPM AT VARIOUS FIELD CURRENTS: field amps volts/rpm torque/armature-amp 0.0 0.001 0.01 0.5 0.009 0.07 1.0 0.017 0.14 1.5 0.024 0.19 2.0 0.030 0.24 2.5 0.035 0.28 3.0 0.038 0.30 3.5 0.040 0.32 Obviously, the armature current is the difference between the applied EMF and the back EMF divided by the armature resistance. For example, if the applied voltage is 105 volts, and the back EMF is 100 volts, then 5/.05 = 100 amps. If either the motor speed or field current is increased, the back EMF would increase, the armature current would decrease, and torque would decrease. At zero armature current there would be no torque. With further increase in motor speed or field current, the armature current would flow in the opposite direction which would make the motor a generator. i.e. it would absorb mechanical power and supply electrical power. The back EMF times the armature current represents real work, the power that is output after frictional losses are deducted. I2R losses include: 1. (Armature current)2 x (Armature Resistance) 2. (Field current)2 x (Field Resistance) For example, with the motor at full continuous power: Speed = 3600 rpm Torque = 30 lb - ft Power = 3600 x 30 x 2 x pi / 550 = 20.5 hp 20.5 x .746 = 15.3 KW Motor Voltage = 144 - .06 x 125 = 136.5 volts Armature Current = (136.5 - 131.5) / 0.04 = 125 amps Field Current = 2.7 amps Back EMF = .0365 x 3600 = 131.5 volts Power Input = 136.5 x 125 + 2.7 x 2.7 x 40 = 17.35 KW Efficiency = 15.3/17.35 = 88 % Note that the (17.35 - 15.3) 2.05 KW loss is dissipated as heat. Now if the field current is increased to 3.5 amps, then the back EMF will equal the battery voltage (i.e. .04 * 3600 = 144 volts) and then the armature current and therefore torque would become 0. Or if the speed was increased to 3798 rpm then the back EMF would again equal battery voltage and the armature current and torque would be 0. With the field current at 2.7 amps and a speed of 3996 rpm, then the armature current would be minus 125 amps (i.e. the motor would be a generator charging the battery) and the torque would be minus 30 lb - ft. If this seems complicated, it really isn't. Just remember the following: 1. The field current determines the strength of the motor's magnetic field. 2. The strength of the magnetic field times speed determines the back EMF. (motor voltage without armature current) 3. The difference between the applied motor voltage and back EMF, divided by the armature resistance, determines the armature current. 4. The strength of the magnetic field times the armature current determines the output torque. 5. The output torque times motor speed determines the output power. 6. The sum of (Armature current)2 x (Armature Resistance) and (Field current)2 x (Field Resistance) determines input power. 7. Output power divided by input power determines efficiency. Series Wound Motor To give a feel for a typical Series Wound Motor, a typical Advanced DC Motor is discussed below. Note that the picture below shows the basic construction of a series wound motor. Typical Advanced DC Motor Advanced DC Motors Model 203-06-4001 amps = (5 * torque) + 85 RPM = (286 * volts) / (10 + torque)0.5 The Advanced DC Motor Model 203-06-4001 is a typical, series wound motor that is often used in Electric Vehicles. It can be reasonably characterized with the above two equations. Note that torque is measured in ft-lbs. The motor is about 8 inches in diameter, almost 15 inches long (not including shaft), and weighs about 107 pounds. It is designed for a maximum voltage of 120 volts. With an input of 91 volts and 178 amps, it can continuously deliver 19 horsepower at 5000 rpm. With an input of 86 volts and 322 amps, it can deliver 31.5 horsepower at 3600 rpm for about 5 minutes. Both of these ratings assume standard ambient temperature. Power generation is limited by heat. Maximum speed is about 8000 rpm, but high speed operation results in greatly increased brush wear. Series wound motors are also known as traction motors since they can generate great torque at low speed. But only for a short time. Great torque requires great current which quickly heats the motor. It should be noted, that comparing electric motors with gasoline engines is like comparing apples and oranges. Gasoline engines are rated at their peak power, and electric motors are rated at their continuous power. It is for this reason that a 30 hp electric motor will generally perform like a 50 hp gasoline engine in a same weight vehicle. Of course the addition of a large number of batteries will diminish the vehicle's ability to accelerate or climb hills.

GENERATOR	3 Phase Rotating magnetic field	ELECTRIC MOTOR

Sally, from the movie, Cars

---

a 1 or 2 month sample:

The safest web sites are viewed best with trusted browsers

FEDERAL EXPERTS SUGGEST DITCHING INTERNET EXPLORER