| In previous articles we have seen how to choose | | | | 000r/m, depending on load. Many of the motors |
| a motor and a Variable Speed Drive (VSD) for an | | | | are available with a reduction gear. Various ratios |
| electric car. In this article we will describe how to | | | | are available. Choose one that gives a reduction |
| choose a car for your electric motor. You may | | | | of between 2:1 (for a high top speed) and 4:1 (for |
| be wanting to: | | | | a lower top speed). Retaining the car's original |
| 1.Convert an existing car to electric operation, | | | | transmission will enable excellent acceleration and |
| using a battery, or | | | | the ability to climb steep hills. Some of the motors |
| 2.Convert an existing car to electric operation, | | | | are water cooled. Should you use one of these, |
| using the Talbot Electric grid connection, or | | | | retain the car's radiator. Join hoses between the |
| 3.Build a car from scratch for electric operation, | | | | radiator and the motor, with an electric water |
| using a battery, or | | | | pump in between. This will provide excellent |
| 4.Build a car from scratch for electric operation, | | | | cooling and allow the rated power of the motor |
| connecting to the electricity supply grid. | | | | to be exceeded. It is advisable to put thermistors |
| Whichever it is, we will show you how to go | | | | in contact with the stator windings to warn of |
| about it. Assuming that your choice is 1, you may | | | | excessive heat build-up. A three-phase induction |
| have an old car with a worn out gasoline engine | | | | motor has an efficiency of 90% or better. Thus |
| that you would like to convert to electric, or you | | | | only 10%, at most, of the input energy is |
| may be looking to purchase an old car from a | | | | manifested as heat. Compare this with a gasoline |
| breaker's yard. If the latter, bear in mind that | | | | engine, which at 60km/h has an efficiency of |
| older technology cars are easier to work on. Try | | | | around 14%, meaning that 86% of the energy of |
| to find a car that is reasonably sound except for | | | | combustion of the fuel has to be removed by the |
| the engine, which latter will be discarded. If it looks | | | | radiator and exhaust system. Such effective |
| a bit shabby you can easily have it reupholstered | | | | cooling will allow the motor to be operated |
| and repainted after conversion. Then you will have | | | | continuously well above its rated power. |
| a fine-looking electric car that could last you a | | | | If you intend building a car from scratch, consider |
| lifetime. If you want it as a local runabout choose | | | | making the body of spheroidal shape, like that of |
| a small car. You can use a smaller battery and | | | | the model "69zulu." Make it in two halves in |
| motor. Decide on the top speed that you want. | | | | fiberglass reinforced epoxy resin and join them. |
| That will determine the size of motor. The | | | | This will give you a very light car with a low drag |
| average light car requires only 5kW to maintain a | | | | coefficient. A 5kW motor in each wheel fairing will |
| speed of 60km/h (37.3 mph) on a level road. If | | | | give more than adequate performance. A 5.6kW |
| you want to do 100km/h (62.1mph) you will need | | | | motor is only 6 inches (150mm) in diameter and |
| a motor of 15kW. On my website you will find a | | | | 9.5 inches (241mm) long and weighs only 6.8kg |
| list of suitable 400Hz motors ranging from 5.6kW | | | | (15 lb). Using separate motors on each wheel |
| up to 150kW. My company does not sell these. If | | | | eliminates the need for a differential. |
| you send me an email from my website I will tell | | | | In order to be able to control the speed of your |
| you where you can get them. | | | | car you will need a VSD. If you are an electronic |
| If your choice is 2 you will not need a large | | | | whizkid you can make your own. Otherwise there |
| lithium-ion battery. Your power will come from the | | | | are many models available commercially. |
| grid. In an emergency, your normal 12 volt | | | | Unfortunately, most of the latter are for 50 or 60 |
| battery will be sufficient. Whichever case you | | | | hertz. If you plan to use a battery, you will need |
| choose, the first thing is to remove the gasoline | | | | one of about 280 volts in order to get 200 volts |
| engine from the car. The gearbox ("transmission") | | | | 3-phase after inversion. |
| may be retained. On a 400Hz supply these | | | | Any problems, feel free to write to me. In any |
| motors rotate at speeds of 11 400r/m to 12 | | | | case, let me know how it goes. Good luck! |