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The development is completed of a new 48″ roll chassis dynamometer for 2 wheel drive (2WD) and 4 wheel drive (4WD) light duty vehicle (LDV). Overhung roll configuration onto the shaft of a hydraulic frame floated AC dynamometer is applied. Braking force measurement accuracy of PAU is ±0.1% of full scale. Vehicle traction force can be measured in high response manner without wheel torquemeter. The above and some new instrumentation architecture are reported. Digital vector controller for PAU and a new digital road load controller enabled 90% step response in 75 ms. Besides that, a dynamic road load verification method and 4WD application is reported.

Asynchronous a.c. dynamometers have recently made a considerable penetration into the market because they permit four-quadrant operation like d.c. dynamometers, and in addition, less maintenance is required. With the controllers using conventional thyristor inverters, however, the torque ripple at low speeds is considerable and the application is limited. In order to solve this problem, we developed controllers using power transistor inverters, this resulted in improvement such as the reduction of physical dimensions of dynamometers and controllers, improvement of power supply power factor and a reduction in torque ripple.