The magnet motor: The prime mover of the future?

The idea of the magnetic motor as a machine powered solely by magnetic force is not new. In fact, as early as , the scholar Petrus Peregrinus Maricourt described how a serrated wheel could be powered by permanent magnets.
However, nothing is known of a successful implementation. Nevertheless, the idea bore fruit: In the 20th century, inventors and hobbyists increasingly dealt with the theory and claimed that they were able to build working magnet motors themselves. To date, however, no one has succeeded in constructing one. But what makes the principle of the magnet motor so interesting?

ZCL are exported all over the world and different industries with quality first. Our belief is to provide our customers with more and better high value-added products. Let's create a better future together.

How could a self-running magnet motor work?

Researchers have been fascinated by the idea of a magnet-driven motor for centuries because it represents a kind of perpetuum mobile. The motor would constantly produce its own energy without depending on an external energy source.
As a result, drive systems would no longer be dependent on petrol, diesel, or electricity - A revolutionary technological advance, also regarding the environmental compatibility of car engines.

In concrete terms, a magnetic motor would consist of several permanent magnets, which are divided into a stator and a rotor. The magnets would repel and attract each other if they were cleverly arranged in a way that ensures a constant rotary motion.
So much for the idea &#; but the implementation is difficult. It primarily fails because there is no energy in magnets themselves. The force in permanent magnets is conservative - so no work is done over a cycle.
As a result, the motor would stop moving after a short time and return to the equilibrium position.
Therefore, according to the rules of physics, a magnetic motor that independently generates free energy cannot exist.

That doesn't stop technology enthusiasts from trying their luck anyway. Most recently, a sensational case occurred in :
An American inventor named Mike Brady marketed a magnetic motor for cars - and sold it to paying customers.
However, the promised marvels of technology were never delivered. Four years later, Brady was charged with aggravated fraud and sentenced to five years in prison.
Since then, it has become quiet around the magnet motor.

Permanent magnet motors: This is how the magnet motor principle works

However, there is one type of working magnet motor that has found its way into everyday life: permanent magnet motors. Permanent magnet motors are used in various everyday devices, such as electric toothbrushes.
In contrast to the non-existent magnetic motor just described, which could be used to generate energy or electricity, they work in a similar way to an AC motor - with the help of electromagnetism. They are therefore dependent on a power supply as an energy source.
The so-called stator contains permanent magnets that generate the magnetic field required for the drive.The advantage is that this type of magnetic motor can be produced in a wide variety of sizes - it is perfect for small applications:

• In windshield wipers
• In air conditioners
• In compressors

Permanent magnet motors are used where a high power-to-weight ratio is required with limited installation space.

Will there ever be large magnet motors for the home?

In times of rising prices for electricity, oil and gas, the search for alternative energy sources is accelerated.
The idea of a simple magnet motor replacing conventional heating or acting as an electricity generator is undoubtedly intriguing. On the Internet you can find a wide variety of building instructions, which supposedly make it possible for laypeople to construct one.
Here's an example:

Build a magnet motor yourself: Instructions

You need:

• A square strip of wood, 20 to 30 mm, about 5 cm long
• A wooden board, 10 cm wide
• Nails
• Non-conductive paint
• Glue
• Sandpaper
• Enameled copper wire
• 50 cm thick floral wire
• 3 to 4 magnets
• 1 m electric cable (single core)
• Various tools
• A battery

In the first step a nail is hammered into the middle of the front side of the square strip. It is important to let the nails stick out about 2 cm on each side. Then isolate around 2 cm of the copper wire with sandpaper and solder this end to one of the nails that have been driven in. The wire is then wrapped around the bar 20 to 30 times so that it runs above the ends.

In the second step insulate a small piece from the other end of the wire and solder it to the other nail. Half of a nail is then painted with the non-conductive paint to insulate it. Do not paint a ring, but a stripe of paint on the nail.
When you turn the anchor, sometimes the insulated and sometimes the uninsulated part must be on top.

In the third step Let's turn to the bearing: to do this, remove the varnish from the floral wire to bend the bearings from it. The wire is wrapped twice around a round tool that should be slightly thicker than the nails - about 10 cm of the wire should be straight at the beginning and end of the spiral. Then place the anchor on the wooden board and mark the position of the nails.

In the fourth step of constructing your magnet motor, drill two small holes per nail and attach the straight ends of the bearing so that you can slide the nails into the spirals. Now put the anchor in the bearings - test if it rotates.
Then you can finally use the magnets. Drill the indentations between the bearings into the wood. Make absolutely sure that they are all facing the same pole.

The final step is to cut the electric wire for the magnet motor in half and solder one end to each bearing.
Now the armature is inserted into the bearings and the cables are connected to a battery. As soon as you kick the motor, it should spin - done!
That's how quickly you can construct a simple - albeit not very powerful - magnet motor.

Conclusion

The technology behind the magnetic motor is fascinating, but it cannot be used profitably in reality.
On the one hand, the construction of such a motor would have to prevent frictional losses during operation and ensure that the motor constantly gains energy at the same time.
However, a technical solution to these problems is currently not available.
Nevertheless, the possibility of building a magnetic motor continues to fascinate many inventors - and who knows, failures may lead to solutions for new, different alternative energy sources.
In any case, we hope that at some point in the future it will be possible to overturn the laws of physics and build a powerful, low-emission magnet motor.

Type of electric motor

A permanent magnet motor is a type of electric motor that uses permanent magnets for the field excitation and a wound armature. The permanent magnets can either be stationary or rotating; interior or exterior to the armature for a radial flux machine or layered with the armature for an axial flux topology. The schematic shows a permanent magnet motor with stationary magnets outside of a brushed armature (a type commonly used on toy slot-cars).

Applications

Electric vehicles

This type of motor is used in GM's Chevrolet Bolt[1] and Volt, and the rear wheel drive of Tesla's Model 3.[2] Recent dual motor Tesla models use a combination of a permanent magnet motor at the back and traditional induction motor at the front.[3]

Permanent magnet motors are more efficient than induction motor or motors with field windings for certain high-efficiency applications such as electric vehicles. Tesla's chief motor designer was quoted discussing these advantages, saying:

It's well known that permanent magnet machines have the benefit of pre-excitation from the magnets, and therefore you have some efficiency benefit for that. Induction machines have perfect flux regulation and therefore you can optimize your efficiency. Both make sense for variable-speed drive single-gear transmission as the drive units of the cars. So, as you know, our Model 3 has a permanent magnet machine now. This is because for the specification of the performance and efficiency, the permanent magnet machine better solved our cost minimization function, and it was optimal for the range and performance target. Quantitatively, the difference is what drives the future of the machine, and it's a trade-off between motor cost, range and battery cost that is determining which technology will be used in the future.[2]

Types

Permanent magnet motors consist of two main types. Surface permanent magnet motors (SPM) and internal permanent magnet (IPM) motors. The main difference is that SPM motors place the magnets on the outside of the rotor while IPM motors place their magnets inside the motor. Benefits to internal magnets include structural integrity and reducing Back EMF. Since holes must be cut into the rotor for the placement of the magnets this creates areas of high reluctance allowing carmakers to obtain some of the benefits of reluctance motors as well as of permanent magnet motors.[4]

Back electromotive force

Back electromotive force (EMF) is also known as the counter-electromotive force. It is the voltage that occurs in electric motors from the relative motion between the stator windings and the rotor&#;s magnetic field. The rotor's geometry determines the waveform's shape.[4]

This effect is not unique to permanent magnet motors. Induction motors also suffer from it. However in an induction motor the fields from the rotor decrease as speed increases. A permanent magnet motor generates its own constant field. This means that as speed increases a voltage is induced linearly with the speed on the stator. This voltage is negative to the voltage provided to the motor and thus is a loss to the overall system.[4]

Permanent magnetic motor materials

Many different permanent magnetic materials are used to drive permanent magnetic motors and vary based on multiple factors, principally necessary magnetic strength and cost. The four primary permanent magnetic materials that are found in the vast majority of industrial applications are neodymium iron boron (NdFeB), samarium cobalt (SmCo), aluminum nickel cobalt (Alnico), and strontium carbonate-iron oxide (also known as &#;ceramic magnet&#;); furthermore, significant materials science research is ongoing into the development of additional non-rare earth (NRE) permanent magnetic materials.

NdFeB Magnets

NdFeB is the strongest of all permanent magnet materials used in industrial applications and sees wide use in many types of permanent magnetic motors, including in disc drive spindle motors, electric vehicle motors, alternators, and sensors, power tools, electricity generators, and magnetic resonance imaging (MRI).[5] NdFeB exhibits a Curie temperature of approximately 320 °C, which is significantly above room temperature, as well as very high remanence, coercivity, and energy product which allow it excellent performance in permanent magnetic applications.[6] The most common method of NdFeB magnet production is sintering of alloyed neodymium, iron, and boron, typically in a nominal composition of approximately Nd14Fe78B8 (at%); sintering promotes growth of the Nd2Fe14B phase which is responsible for the characteristic strong magnetic behavior seen in NdFeB magnets. However, this also leads to corrosion vulnerability in NdFeB magnets along sintered grain boundaries, which requires alleviation through the addition of copper-nickel or aluminum-based metallic surface coatings.[7][8] In addition, the high cost, rarity, and radioactive waste associated with production of the metal neodymium as an input means that NdFeB magnets are very financially and environmentally expensive.[9]

SmCo Magnets

SmCo is a strong permanent magnetic material of comparable strength to NdFeB and is used across range of applications including very high-performance vehicle electric motors, NMR spectrometers, turbomachinery, and frictionless bearings.[10] While NdFeB magnets exhibit a superior magnetic field, SmCo magnets have higher coercivity (i.e., less vulnerability to demagnetization) and better corrosion resistance. Furthermore, SmCo magnets have a Curie temperature exceeding 700 °C and superior temperature stability compared to NdFeB, making them more optimal for permanent magnetic motor applications involving high temperatures or cryogenic conditions.[11][12] However, SmCo magnets contain a higher fraction of rare earth metals than NdFeB magnets, making them even more expensive and subject to the scarcity and environmental concerns of production; as such, SmCo magnets are now typically only used in specialty application cases where their particular temperature and coercivity advantages are significant.

Alnico is a NRE permanent magnetic material used in permanent magnet motor applications such as magnetic speed and flow sensors, electric generators, and consumer goods.  These magnets exhibit weaker performance in comparison to NdFeB and SmCo counterparts but still maintain high coercivity and are far cheaper due to their lack of rare earth metals. Furthermore, the high fraction of both aluminum and iron within these magnets lends them excellent corrosion resistance, electrical conductivity, and high-temperature stability; Alnico has one of the highest Curie temperatures of any known magnetic material at nearly 800°C.[13] Despite this, Alnico&#;s comparatively low magnetic strength means it is one of the permanent magnets most susceptible to demagnetization, especially at cryogenic temperatures when constituent ferritic iron may transition to superconductivity.[14]

Ceramic Magnets

Strontium carbonate and iron oxide, also known as a &#;ceramic&#; or &#;ferrite&#; magnet, is a NRE permanent magnetic material found in permanent magnet motor applications such as power tools, industrial magnetic separation processes, and automotive sensors. Ceramic magnets are significantly weaker than either SmCo or NdFeB but are generally stronger than Alnico magnets, in addition to being both more corrosion resistant and lower cost.[15] However, ceramic magnets exhibit poorer temperature stability in comparison to Alnico and lose magnetization relatively easily when exposed to temperature extremes both hot and cold, with a much lower Curie temperature around 450 °C and a susceptibility to the same ferrite-driven demagnetization phenomena as Alnico under cryogenic conditions.[14]

Emerging Permanent Magnetic Motor Materials

Development of non-rare earth, low cost, mechanically robust, and high strength permanent magnetic materials is a vigorous and ongoing area of research. Some notable materials systems of current interest include iron-cobalt-molybdenum ternary alloys,[16] nanostructured cobalt-platinum alloys,[17] and meteoric-type ordered iron-nickel alloys.[18]

Environmental and supply concerns

Rare earth production has the consequence of generating waste with elevated radioactivity compared to the natural radioactivity of the ores (waste that is referred to by the US EPA as TENORM, or Technologically Enhanced Naturally Occurring Radioactive Materials). China, the top producer of neodymium, restricted shipments to Japan in during a controversy over disputed ownership of islands. China imposed strict export quotas on several rare earth metals, saying it wanted to control pollution and preserve resources. The quotas were lifted in . Although neodymium is relatively abundant, global demand for neodymium outstripped production by about 10% in .[3]

See also

References

• Vavra, Chris (-01-31). "Understanding permanent magnet motors". Control Engineering .

The company is the world’s best Permanent Magnet Rotor Manufacturer for Large Chemical Plants supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.