690071 Electric-Wheel Vehicle Propulsion System C. W. King and George C. Collins Delco-Remy Div., General Motors Corp. Walter Slabiak Propulsion Systems Laboratory, U. S. Army Tank Automotive Command D-C TRACTION motors have been used extensively in lo­ comotive propulsion and, to a lesser degree, in large off- highway earthmovers and trucks. This type of motor has the torque speed characteristics and control characteristics suit­ able for vehicle propulsion, but its speed, weight, and cool­ ing limitations have restricted its application to large, slow- speed vehicles and small, low performance vehicles. A more ideal propulsion motor would provide the high-torque capabilities of the d-c motor with the high speed capability of the a-c motor, have the good controllability of the d-c motor, and permit effective cooling. Such a motor would greatly widen the potential areas of application for vehicular electric drives. Several years ago, Delco-Remy Div., General Motors Corp. began a study to combine electric motor technology with solid- state electronic technology in order to achieve a more de­ sirable propulsion motor with the aforementioned charac­ teristics. This study resulted in a high performance, var­ iable speed motor that could be operated from d-c or from a-c as a self-synchronous motor. An operational six-wheel electric military truck utiliz­ing the new motor concept has been developed by Delco- Remy in a joint program with the United States Army Tank Automotive Command (USATACOM). The development program leading to the operational test-bed truck was funded by USATACOM beginning in June 1962. The first step was a study to determine the technical feasibility of electric propulsion. Following this, a half size motor was designed, built, and evaluated. The next step was to study the new system by dynamometer testing two full-sized wheel assemblies powered by an engine- driven alternator. This step permitted an evaluation of the interaction of multiple motors as well as the develop­ ment of the control systems necessary to operate a com­ plete propulsion system. After this phase, a complete truck system was built with the final step being performance and durability tests. This paper will describe the application of the new mo­ tors in the M- 35 test bed and the subsystems and controls necessary to achieve a functional vehicle. Preliminary test results also are reviewed. ABSTRACT An electric wheel vehicle propulsion system has several potential advantages in the area of mobility, vehicle-design flexibility, and the accomplishment of multiple functions. Such a system has been developed by Delco-Remy Div. of General Motors, as prime contractor to USATACOM, and has been applied to an M-35 military vehicle. The system consists of six-wheel mounted and unique brushless syn­ chronous motors powered by an engine- driven alternator. This paper describes the application of these brushless synchronous motors in the M-35 vehicle which serves as a testbed and reviews the subsystems necessary to achieve a functional vehicle. Subsystems examined include the power- train elements (engine, alternator, power converters, motors), the dynamic braking system, the engine alternator control loop, the motor field control loop, and the operator controls. Preliminary test results also are reviewed. 372 Downloaded from SAE International by Columbia Univ, Monday, August 20, 2018Fig. 1 - M-35 electric wheel test bed PROPULSION SYSTEM DESCRIPTION PROPULSION SYSTEM - The electric drive system has been applied to an M-35, 2-1/2 ton truck (Fig. 1) for test and evaluation purposes. While this vehicle will not ex­ ploit all the potential advantages of an electric drive sys­ tem, it does provide an economical test bed for evaluating electric propulsion. Also, extensive data is available on the M-35 truck with a conventional transmission, thus providing a yardstick for comparison. The major elements of t