How does a rare earth motor work. 
image of a scooter transaxle

A Rare Earth magnet motor uses magnets that are
at least 5 times more powerful than normal DC
permanent magnets. Stick one of these magnets
on your fridge and you will need a crow bar to get
it off. When used in a motor to drive an electric
scooter the maximum power increases slightly.
However the low and midrange torque increases
dramatically. Sort of like have a turbo charger on
your car engine. The efficiency away from optimal revs and under severe load is markedly improved all the while producing far less heat.

A Rare Earth motor is the biggest step forward in small electric vehicles in quiet some time.  Not only does it use considerably less power to drive the scooter but it also recovers more power when driving downhill. These two main factors may increase range by up to 35%. Particularly if the scooter spends a lot of time going up and down hill or travelling across grass. The positives are the life and range of the batteries will be significantly enhanced. The uphill performance will be noticeably better.  And the motor will almost certainly outlast the scooter. Because of the high cost of the magnets usually these motors are only built to the highest standard. I am yet to see a cheap and nasty version.

For a long time a DC permanent magnet motor has been used for a variety of automotive uses. i.e starter motors, wiper motors, electric window motors etc. For a defined use at set revs this works fine.  Many years ago it was the obvious and only choice to power electric scooters. However there was and still exists a fundamental flaw in using a DC permanent magnet motor to power an electric scooter. At peak revs a DC permanent magnet motor can be up to 87% efficient. That is for 100% of battery power in 87% comes out in usable power. The rest being lost to electrical eddy's, heat and friction.  However away from peak revs efficiency can drop off markedly. This would be that when the scooter is running at low to medium speeds under load such as hill climbing or traveling across grass. This is what really knocks the guts out of batteries. As much as anything a rare earth motor has overcome this basic flaw in scooter design.

For many years I have been involved with a government owned plant in China producing modern motors both DC permanent magnet and Rare Earth magnet. These are used in aircraft and space craft for a variety of purposes. i.e raising and lowering under carriages, flap and control surface adjustments etc. Over the past four years  a great deal of resources were applied to making (inventing) a rare earth motor suitable for scooter use. In your home the most common use of a rare earth motor albeit in a miniature form is in computer hard drives, DVD drives and possibly a quality cordless drill or even the latest vacuum cleaners. Because of the immense power of these magnets it is easy to control very accurately as a stepper motor. This trait is not what is needed in a scooter motor. This would make the drive very jerky indeed.

After almost 4 years of testing a new patented shaped magnet internal layout and armature configuration has overcome this issue nicely and allows the motor to have a programmable run on creating the desired smooth and precise operation. Having just ridden the latest model Lotus Blake Montana Magnific with a rare earth magnet motor I am amazed at how well this new technology has evolved and been adapted for use as a scooter motor. I was present when endurance and severe load testing was being done. There is nothing a scooter user could ever do to make one of these motors fail. This technology will surely now find its way outside of aerospace use and through much deeper into all electric vehicle technology.The main obstacle to much larger scale usage is as always extreme cost.  These motors are not cheap and won't be for some time to come especially in larger sizes.

Service warning:  A rare earth motor should only be disassembled by person experienced at such and with the correct equipment to do so. Be aware that the force required to remove the armature from the magnetic housing is extreme. Once the point of magnetic force is overcome the armature may be propelled out of the housing at great speed. copyright 2009  reproduced with permission

copyright 2012  LB designs