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An E-bus, originally designed in 1967 for crosstown operation on 42nd Street, New York City, has its design brought up-to-date. Nickel-cadmium batteries were to be used with INCH* (INterim CHarging) at both ends of the route. The technologies available at that time made a demonstration project prohibitively expensive. Many aspects of the design have been used in successful E-bus demonstrations since 1971 in Europe. One of these projects is the basis of much of the updated design. Many of the technical aspects of the 1967 design which were then experimental, are now proven. Some of these are: over-excited shunt instead of series motors; a transistorized field chopper plus a thyristor armature chopper; regenerative braking; automatic and shock-proof connection to the battery-charging terminals; single point watering, and INCH. Calculations indicate that with Na/S batteries, E-buses can be used on north-south routes, with 2 interim charges of five minutes each.

The hybrid* passenger road vehicle presents a difficult problem when one considers establishing meaningful test procedures for determining performance and energy and fuel consumption characteristics. This is due to the continuum of possibilities of division of use of the energy stores available for propulsion during the drive mission. The continuum, or spectrum, varies from one extreme operation as an all-electric, where no on-board liquid petroleum fuel is used, to the other extreme operation as an all-ICE, where no electricity is used. This paper reviews the background of hybrids and discusses testing to date of some hybrids. Three proposed methods of testing hybrids that have been published or proposed, are examined. The results presented are mainly those determined by IEC TC/69 WG5 “Hybrid Electric Road Vehicles” at a meeting in London on September 17 and 18, 1981.

Data are presented to show how electric vehicles will travel approximately twice as far per ton of coal burned to produce electricity for EV propulsion, than will an ICE vehicle burning the synfuel produced from an equal amount of coal. These figures are based on pessimistic calculations of the efficiencies of electricity generation, transmission, battery charging and EV drivetrains. The synfuel calculations are based on optimistic upper limits of coal conversion efficiency and ICE systems’ efficiencies. EVs are less harmful to the environment than conventional vehicles. The emissions from coal-burning power plants are more readily controlled than the pollutants from refineries that convert coal to synfuel. The emissions from EVs are negligible, whereas those from ICEs still have not been reduced to the levels originally mandated for 1976.

Tests performed on three different configurations of hybrid vehicles establish that significant quantities of on-board petroleum fuel can be conserved by allowing the batteries to be discharged during the driving mission. The depleted batteries are then charged when the vehicle is not in use. Savings of as much as 50% of the on-board petroleum have been experienced with tests on the FDC. On SAE J227a, gasoline FE greater than 50 mpg was measured. Part of the energy for driving is thus transferred from on-board petroleum to off-board electricity generated from coal, hydro-electric or nuclear power plants, with no sacrifice in vehicle performance. The total energy used, when considering the replacement of energy to recharge the batteries, is analyzed. The results are favorable for the hybrid. A recommended new driving cycle for testing hybrids is discussed briefly.

A “compound” parallel ICE/battery-electric hybrid automobile has yielded emissions (gms/mi) less than 0.41 HC, 3.40 CO, and 1.0 NOx on the FDP when tested by the EPA. Fuel economy increased 50% on the FEC with partial battery depletion. The 4,100 lb. curb weight vehicle has a top speed over 70 mph, with 0-60 mph in 16 seconds. Low fuel consumption was not a goal in this vehicle. The requirement of 10 mpg was set in 1970 for the FCCIP. FE of 30 mpg or more is projected with known techniques for reducing fuel consumption. A small ICE and a dc dynamotor (generator/motor) on the same shaft drive the vehicle through a conventional clutch and gears. HC and CO are reduced by a thermal reactor. EGR reduces NOx. The ICE operates with a quasi-constant manifold vacuum. Analysis show that in commuter applications, fuel economy can be increased 60% with partial battery depletion, by hybridizing any conventional car.

A standard station wagon has been converted to an electronic car employing nickel-cadmium batteries for power, and an SCR chopper for speed control and regenerative braking. With this vehicle we can simulate the acceleration and deceleration performance characteristics of a hybrid battery system which will ulitmately use high energy density batteries for range, and nickel-cadmium batteries for acceleration and braking. Acceptable acceleration to top speed and acceptable rates of braking down to very low speeds, are achieved. Circuits and some performance characteristics are described.