Hybrid & Electric Vehicle Brake Testing
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Microface - generally regarded by its customers as the best dynamometer automators in the world.Jacob Slevin
Hybrid vehicles pose significant challenges and significant rewards to the brake designer. With careful design the brakes can be constructed lighter and smaller than the same weight non regenerative brake system because some of the energy can be returned to a battery. This is very significant for ride comfort as unsprung weight can be reduced.
Combined Brake Effects
Conventionally brakes are rated to brake the full weight of the vehicle on a Dynamometer. In practice for heavy braking over 10% of the work is done by the tyre in the form of slip and hysteresis of the rubber. This is rarely taken into account.
However now that another 10 to 15% of the work in braking can be returned to the battery the combined effect is becoming worth considering. The effect of both of these losses can be modelled and in addition a small contribution is provided by the road load equation. All these effects can be included in the vehicle model so that the true heat input to the brake can be produced providing a more reliable and accurate dyno test.
Finally the brake cooling due to wind can be not straightforward as the vehicle body or the wheel rim design can seriously affect this.
If Microface is provided with brake temperature cool-down profiles at different speeds and wind angles this can be modelled on the Dynamometer to produce matching heat loss making the dyno simulation even more accurate.