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GridElectric is a transport system in which the road vehicles are powered by electric motors. Power is supplied by banks of solar panels at the sides of the road, and where necessary, by solar panels on the walls and roofs of adjacent buildings. The solar panels are connected together to form a grid supplying power to the vehicles via inserts in the road, as shown above.

When the solar power is insufficient, the power requirement is augmented by power from the national grid, as shown. A contact member on the vehicle makes electrical contact with the conductor in the road and the metal extrusion. The system is intrinsically safe. Vehicles have full mobility within the confines of the road.

The road insert has three parts: a metal extrusion, a plastic extrusion, and a metal conductor. The conductor could be copper or aluminum, or a combination of steel and aluminum if there is a danger of conductor theft. To accommodate the insert, a T-shaped groove is cut in the road aggregate, parallel to the road, and in the center of each lane, using a composite diamond saw. The insert is then placed in the groove and retained there by suitable bolts, or other suitable means.

A complete contact member as attached to the vehicle is shown on page 6. The mounting plate is attached to the underside of the vehicle. Before contact is made with the conductor in the insert, the arms will be in the raised position. The position sensor controls the servo motor on the left which rotates the arms until the sliding contact is directly above the conductor. Once this situation is attained the servo motor on the right lowers the contact assembly until the wheels make contact with the metal extrusion. If the positioning and orientation of the assembly is slightly out, the wheels will complete the alignment as shown in the figures on page 7. Continued downward movement of the arms compresses the rubber spring and forces the sliding contact into contact with the conductor.

The parallelogram configuration of the arms ensures that the sliding contact is parallel to the vehicle center line when there is no torque on the sliding contact. When the vehicle is not traveling parallel to the road insert, the rubber spring allows for rotation of the sliding contact in the horizontal plane. When changing lanes, the contact member remains in the insert, lateral displacement of the contact from the center line of the vehicle being accommodated by rotation of the arms in the horizontal direction. At the extremity of the rotation the arms are raised by the servo motor on the right, while the servo motor on the left rotates the arms to the opposite extremity, where the other servo motor lowers the assembly into the groove in the adjoining lane of the road.

The above figures show how the final positioning and orientation are effected by the peculiarly shaped wheels. If the position and orientation are not correct, the wheels make the correction as they are pushed down into the V-groove of the insert, as shown. Once they are correctly positioned continued downward force on the plate above the rubber spring forces the sliding contact (Red) into the groove in the conductor (green). An alternative to the plastic extrusion shown in the figures on page 5 would be to use a wooden or Portland cement mortar support (shown yellow) for the conductor. Looking at the right-hand figure above, the wheel makes contact with the metal extrusion, which is at ground potential, and is connected to one pole of a three-phase inverter. The conductor (green) makes contact with the sliding contact (red), through which it is connected to the other pole of the three-phase inverter. The output from the inverter is connected to a three-phase induction motor which propels the vehicle.

A useful modification is shown in the figure below. This shows an insert with two conductors. The advantage of this is that one conductor may be at +v with respect to ground and the other at -v. Light vehicles may then be operated on a voltage of v, and heavy vehicles on 2v. An example would be operating light vehicles on v=282 volts, 400Hz, while heavy vehicles may then be operated on 564 volts, 50/60Hz. Using 282 volts DC enables an output of 200 volts from the three-phase inverter. 200 volts, 400Hz is commonly used on ships and some aircraft.

400Hz motors have a much higher power-to-mass ratio than motors of 50/60Hz and are used on ships and aircraft to save space and mass. For this same reason they are suitable for powering light road vehicles. Very large motors in the 200 volt, 400Hz range, are to the best of my knowledge not available. Therefore 50/60 Hz 400 volt motors may be more suitable for heavy vehicles. The speed of the motors may be controlled by varying the output frequency of the inverter. The voltage should also be varied. The general rule is that the voltage should be varied in the same proportion as the frequency. The voltage can be varied by means of pulse width modulation (PWM).

The system described is intended to gradually supersede the powering of road motor vehicles by

petroleum-derived fuels. The system could be introduced initially on busy inter-city roads, such as the interstate highways in the USA and on the national roads of South Africa. Since it is expected to take some time to modify all the roads by placing inserts in the lanes, it may be necessary to make use of hybrid vehicles in the interim period. For example, a typical front wheel drive motor car may be modified, or designed from scratch, with electric motors driving the rear wheels, or with in-wheel electric motors on all wheels. For rear wheel drive cars, an electric motor with internal reduction gear may be incorporated in the drive train, presumably by attaching it to the final drive. Cars so modified, or manufactured, may then operate on electric power from the composite grid illustrated on page 4, when available, and on their gasoline engines, when power from the composite grid is not available. The result will be a substantial saving in energy costs.

Heavy vehicles may be modified in a similar way to rear wheel drive cars, by incorporating anelectric motor in the drive train, or by powering the axles of semi-trailers, as shown in the figure .

This preliminary application will result in reduced operating costs. Eventually, when all the roads

Patent Pending The system described in this document is the subject of Patent Application Number ZA2007/08959