Welcome to 4x4 Electric Vehicle

Motor prototype

Monday, 04 July 2011 09:54 administrator

In spite of the long stretch without news we have been busy. Our initial axial flux motor design turned out to be very expensive to build and we decided to go back to the design board, in order to make it simpler; we also decided to build a small prototype that would serve to validate all the design parameters.

Since we were designing everything afresh, we opted for a hub motor of the outrunner type, which would allow the wheel rim to be directly bolted onto it; the prototype should be a scaled down version of this design, built with readily available parts as far as possible.

The design was then made for a 100 mm OD motor of around 300 Watt at 600 rpm, which was built around a bicycle hub. The stator has 9 coils and the rotor has 12 neodymium magnets; one of the rotor ends is open. In the full scale version the closed end will receive the wheel and the open end will be made to receive a disc brake. We are now going to run a series of lab tests before stepping up to the full scale motor.

Last Updated on Monday, 04 July 2011 10:25

Talking about motors

Friday, 18 February 2011 17:37 administrator

The choice of motors for the project was one of our first tasks and not an easy one. Our first approach was to try using parts found in junkyards, either motors or generators which could afterwards be converted to suitable motors. We rejected commutator DC motors from the start and studied truck alternators that could function as motors with suitable electronic controllers, but this option didn't seem very appealing, namely because alternators have brushes and slip rings. After these initial considerations we soon decided that the motors we needed were brushless permanent magnet synchros, also known as brushless DC (BLDC) motors.

Market research conducted on the internet revealed some manufacturers of motors that we could use, both hub and shaft drive types, costing well over $1000 each. Although such motors could be used, the cost and some less than ideal characteristics placed us on the path to designing our own motors. We decided upon an axial flux design, with a disc rotor with embedded disc shaped magnets and a stator made from U transformer cores; we will be giving some details of this design in future posts.

Last Updated on Friday, 18 February 2011 17:48

We are working on it

Monday, 07 February 2011 14:15 administrator

We are working on a project for the conversion of a light off-road vehicle into full electric with 4 motors, one for each wheel. This site will be redesigned to provide news of the developments; please visit us again in the near future.

Rationale

Tuesday, 15 February 2011 15:36 administrator

Many people have made EV conversions, not only of family cars but also off-roads; the vast majority of those conversions consists in the replacement of the internal combustion engine (ICE) by an electric motor coupled to the existing transmission. We think that this kind of conversion underuses the potential of an electric vehicle, first and foremost because the mechanical transmission is lossy, but also because it does not apply optimal torque and power to the wheels in case of turns and loss of grip. In off-road usage one commonly finds situations when one or several wheels loose grip and proper redistribution of power by the other wheels is a great advantage.

We are planning to make a conversion with one motor per wheel, with a suitable controller that determines the speed of each wheel in every circumstance, thus avoiding the need for mechanical differentials. The motors must be designed for direct drive, without reducing gears, either the hub type or the type to be placed centrally in each axle, driving the wheels through modified drive shafts. The former solution is more elegant and altogether simpler but the latter is probably easier to implement, reducing the need to design mechanically vital parts; this will be, in principle, our choice.

We have chosen to work on a vehicle with 2 rigid axles and leaf spring suspension, since we believe this offers the greatest versatility for transformations. The axles will have to be modified, ending up in the form of a truncated A with the 2 motors suspended from the central section; the figure illustrates this concept.