Research On The High Efficiency Area Of Engines Exclusive For Hybrid Electric Vehicle

Nowadays there are four ways to improve the economical efficiency for HEV,(1)regenerative braking (2) cancelling engine idle (3) low power engines selecting (4)reasonable strategies developing. Interiorly, selecting low power engines is simplyconsidered as cutting engine’s power down. Manufacturers choose engines just because theyare powerful enough. Actually, another meaning of low power engines is choosing anengine whose MAP is set to an appropriate station. So, not choosing, but making ordeveloping is the worthy work we should do, to develop an appropriative engine for HEV.We are familiar with the conception of engine high efficiency area, which is the lowerequal fuel consumption curve on the engine MAP, and every engine has its own one. But thehigh frequency area, which contains most engine working points, varies with differentdriving cycles because of different average velocity, different max velocity, differentacceleration and etc. In one word, each driving cycle corresponding one engine highfrequency area and it is not influenced by any sole factor. The original method to find outthis area is the simple mathematic statistics, lack of convincingness.There are so many working models for HEV and it works in such a complex way.However, we can also fit an f(x) in which x is the velocity and f(x) is the engine speed.First, this paper divide a simple driving cycle into multi-normal distributions at first,then, find out the main factors that affect most by means of PCA. Fit the main factors intofunction Z(Prins), and extract proper values of driving cycle and function f(x) in order tocalculate the engine high frequency area. As a conclusion, we found that this new method isreliable and there are many differences between the high efficiency area and the highfrequency area.Then, analysis the characteristic of distribution of HEV’s engine MAP, to insure asimilar area as engine high efficiency area as its engine high frequency area, to make it easy to transform into a new distribution of engine MAP.At last，analysis the improvement of economical efficiency with alternation of HEV’sengine MAP, put forward a method to evaluate engines exclusive for HEV.All that is a new method to calculate HEV’s engine high frequency speed areadepending on drive cycles, which have much effect on the high frequency velocity area.Which is superior of the original methods, simply depend on mathematic statistics. All theseworks deepen the conception and the necessity of engines exclusive for HEV.