As predicted in an article in an American magazine, there was severe energy crisis in 1973. This led to several reports forecasting phasing out of the internal combustion engine and various alternatives were seriously considered for its replacement. The electric motor was considered an alternative, but due to its heavy structure, it was rejected.
During that period, the traditional DC traction motor was only available and it was too heavy to satisfy the car owners accustomed to driving gasoline-powered cars. Although, the three-phase induction motor had a better power-to-mass ratio but that was mainly constant speed equipment and therefore, was also not considered suitable.
In the 1960s power semiconductor equipment were introduced, which facilitated the use of the solid state Variable Speed Drive (VSD). The speed of a three-phase induction motor could then be changed by altering the frequency and the voltage.
While the normal supply frequency in the US is 60Hz, in rest of the countries in the world, the frequency is 50Hz. A 60Hz two-pole motor rotates at around 3420 rpm on best possible load; whereas the corresponding speed for a four-pole motor is 1710 rpm. Similarly, for a 50 Hz motor the related speeds are 2850 rpm and 1425 rpm.
The power-to-mass ratios of such motors are comparable to those of a high speed diesel engine In order to derive best possible power-to-mass ratios, one can opt for higher frequencies. The velocity of rotation of a motor with a specified number of poles is relative to the frequency. Higher frequency motors revolve at high speeds and thus have much better power-to-mass ratios.
The electrical equipment in aircraft is designed to have ‘triple redundancy’ factor. In other words, three motors are required for the same specific job, any one of which must be capable of performing the tasks of the other two. With such strict conditions, mass and volume turn out to be very vital.
Motors and alternators utilized on aircraft normally operate therefore on a frequency of 400 Hz. Nevertheless, some aircrafts utilize 1200 Hz. Space and mass specifications are also crucial aspects for ships. The electrical systems on ships are usually run on 400Hz.
Here are the advantages of utilizing high frequency motors:
While a 60 Hz motor with two pole-pairs revolves at 2840rpm and has a power-to mass ratio of 250 W/kg, a 400 Hz motor with two pole pairs rotate at 22,720 rpm and has a power-to-mass 2000W/kg.
Likewise, for four pole motors, the corresponding details are:
1704rpm and 125W/kg for 60Hz and 11 360rpm and 1000W/kg for 400Hz. High frequency motors have small size and mass and for a specified electric power, their torque is much smaller than that of a low frequency motor. They compensate for it by rotating at proportionately high speeds.
As the torque is lesser, the motor can be smaller and lighter. An aluminum frame motor and aluminum squirrel cage motor have, therefore, different parameters in terms of size and mass and frequency. It is clear from the analysis of the specifications of different type of electric motors that electrical motors compare satisfactorily with internal combustion engines in power-to-mass ratio.
In addition, they are more compact, easier to assemble and do not need other supplementary equipment as in the case of an internal combustion engine, like radiator, exhaust system, starter motor, alternator, transmission etc.
From the foregoing analysis, rapid technological developments in designing electric motors, ever rising prices of gasoline and increased awareness among people about emission of harmful gases by the internal combustion engine have made electric cars popular and many people are trying to convert their gasoline-powered cars into electric cars.
With ever increasing prices of gasoline and the environment getting polluted due to emissions of harmful gases by the petroleum products, more and more people are trying to switch over from gasoline-powered vehicles to electric cars.
Those having a gasoline-powered internal combustion engine car need not buy a new electric car; instead they can replace the present internal combustion engine with electric motor. Electric motors are of two types: alternating current (AC) motors and direct current (DC) motors. Anyone of the two types can be fitted in an electric car.
However, electric cars with AC motor are very uncommon except those large electric cars produced by leading automobile manufacturers. AC motors generate more electric current for their size and are lighter than DC motors.
In contrast, AC motors are also complex for those interested in installing it in their vehicles as a do-it-yourself (DIY) job and in addition, they are costlier than DC motors. This is why most people prefer DC motors for all electric car conversion jobs. There are several advantages of using DC motor for electric car conversion jobs.
Firstly, it is easier to purchase if one is familiar with specifications and other details of DC motors. One can get reconditioned DC motors at very affordable prices in local markets; sometimes even at throwaway prices. The reconditioned motors are durable and if it was reconditioned lately, one can expect to last even longer than the car itself.
Electric DC motors are known by their diameter and the larger diameter motors have the capacity to generate higher horsepower. However, one should keep in mind that this size of motor consumes more electric power and needs more number of batteries.
It is also necessary to charge the batteries quite often. It is, therefore, important to strike a balance between electric power and reasonableness. A DC motor with a diameter between nine and thirteen inches will meet all the requirements and these are the sizes normally used in electric car conversions.
A motor in this range of diameter offers enough output as well as horsepower to achieve a speed of 55 miles per hour and can easily cover a distance of 150 to 200 miles between charges. A DC motor in the 9 to 13 inch diameter motor range will also function properly with deep cycle batteries, which are widely preferred for electric car conversions as DIY tasks It is a fairly simple job to install a motor in the present internal combustion engine vehicle for converting it into an electric car provided the guidelines are strictly implemented.
One obviously needs a helper for this as the motor weighs approximately 150 pounds. A new electric car motor will cost anywhere between $1000 and $5000 depending on its diameter. However, it is not advisable to go in for a new motor as a reconditioned motor costs very little and lasts much longer than the car itself.
One can get a lot of these inexpensive and durable motors in the local markets, if only he can devote some time. This saves as much as $1000 or even more. In this effort, the services of a knowledgeable guide are very useful. The time required for installing a new electric car motor or a reconditioned one is the same. It is also important to look for a used electric car motor in the right places so that one can get the best deal and save some money.
Electric car conversion involves a careful planning and step by step approach carefully following the guidelines on car conversion. Before taking up car conversion, one should make sure that the controller, motor, batteries and are other parts required fit properly into the car one proposes to convert into an electric vehicle .With proper planning, suitable guidance, it is possible to complete the total car conversion much below $500.
Your decision to convert your gas powered car into an electric car is a smart one. You will not only be doing the nature a favor but will also be reducing the cost of driving your car.
Before you embark on your electric car conversion project, it is necessary to decide what motor you are going to install on your electric car. An electric car can have either an AC motor or a DC motor.
AC motor works on alternating current while a DC motor uses electricity stored in batteries. There are both advantages and disadvantages in using Ac Motor and DC motor for your electric car. The power input for an AC motor is more.
An AC motor needs volts in between 48 and 96 whereas a DC motor needs only 6 or 9 volts. Since an AC motor uses more volts, additional safety features must be incorporated into an electric car’s design.
AC motors are preferred over DC motors on two counts; they are lighter in weight and a mechanism that produces power while you apply the brake can be installed. The power thus produced is used to recharge the batteries of the car. Because of these advantages, most commercially produced electric cars use AC motors.
The main disadvantages of an AC motor are its high cost and the difficulty in installation. Only skilled technicians can install an AC motor on an electric car. If an AC motor is used in the car, there has to be a converter to convert AC into DC.
While AC is converted into DC, there will be some current loss too. DC motors are cheaper than AC motors and it is easy to install them. There is no need of invertors and there is no loss of power. A DC motor lasts longer than an AC motor.
To reduce the cost of converting your car into an electric car, you can use a second hand DC motor which you can get from the local scrap dealer at a very low price. If proper care is taken, a second hand DC motor will last throughout the life of your electric car. An ideal DC motor for your electric car should measure between 9 and 13 inches in diameter.
A DC motor of this size will not be too heavy and it will be powerful enough to propel the car. Taking all the advantages of a DC motor into consideration, car conversion using a DC motor is the best option. The only things where you need to pay special attention are the size of the motor and its voltage input.
A DC motor just needs connection to the batteries through the control unit which is again connected to the accelerator of the car. The accelerator cable of an electric car is similar in function to the carburetor which controls the amount of fuel that goes into the engine of a gas powered car.
Depending on the size and voltage input of the DC motor, the battery size has to be changed. As a general rule, a bigger sized and more powerful motor will need more voltage and therefore the battery has to be a bigger one.