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| EXAMPLE OF PIEZOELECTRIC GENERATOR DEVELOPMENT FOR UNLIMITED AUTONOMY OF A CAR ANALOGUE TO TESLA MODEL S60 | |||
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Electric car with a battery of 60 KWh, which gives an autonomy of 370 km (As Tesla Model S 60).
Based on the fact that the speed limit is 130 km/h, the consumption time (CT) battery will be:
TC = Autonomy / Maximum speed = 370 km / 130 km/h = 2.85 hours
The formula that gives us the duration of charging (DC) is:
Then:
- POUT (kW) = (Battery Capacity (KWh) / DC (h)) x efficiency (%)
Thus, the power that our piezoelectric generator must produce for a car as Tesla Model S60, considering a 75% efficiency, is:
It is considered Piezoelectric elements (Eji,i) are cylindrical in shape. With height = 15 mm, diameter = 2 mm and piezoelectric voltage constant g33 = 0.06 Vm/N, and a triggering force F received by each of the piezoelectric modules Mji,i is set by the input force control device 700 to be F = 5 N. Then the voltage generated by the piezoelectric element is: |
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After AC/DC converter Cji,i each module Mji,i that can gives an output DC voltage Vji,i of 1.400 V, and the speed at which the triggering force F is applied is set to give an output current Iji,i is 20 mA.
Vji,i = 1.400 V Iji,i = 20 mA
We consider an array where all the sets i have the same number of piezoelectric modules Mji,i in serial connection:
And considering for example 30 times the number of sets than the number of modules in each set, because we are interested to increase the intensity much more than the voltage:
30 J = i |
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Then the output Voltage and the Output current of our piezoelectric generator is:
Vout-tot = Vji,i x j Iout-tot = Iji,i x I
And consequently:
Pout-tot-T = Vout-tot x Iout-tot = (Vji,i x j) x (Iji,i x i) = (1.400 j) x (0,02 i) 26350 = (1.400 j) x (0,02 x 30 j) 26350 = (1.400 x 0,02 x 30 ) j^2 26350 = 840 j^2 j^2 = 26350 / 840 = 31,37 j = 5,6
As a result, the number of modules and the number of set are:
j = 6 i = 168
After defined the array 400 the total output values of our piezoelectric generator can be determined:
- Vout-tot = Vji,i x j = 1.400 x 6 = 8.400 V - Iout-tot = Iji,i x i = 0,020 × 168 = 3,36 A - Pout-tot-T = Vout-tot x Iout-tot = 8.400 x 3,36 = 28,22 KW |
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| We remember that in order to give unlimited autonomy to our electric vehicle, we need a generator able to generate 26.35 KW | |||
Consider a car similar to mentioned Tesla Model S60, that has a weight of 2.175 kg, and considering only the 1G acceleration of gravity, this weight could cause an effort of 21.337 N. Although usually in the automotive sector, devices are developed to support between 5G and 10G.
To give unlimited autonomy to our electric vehicle, we have arranged 1 unique piezoelectric generator in 1 wheel of the vehicle using 6 x 168 = 1.008 piezoelectric modules, with a triggering force of 5 N, and consequently a total force used of 5.040 N or in other words 514 Kg of the available 21.337 N or in other words 2.175 Kg considering only 1G.
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Although in this example we have talked about unlimited autonomy only installing 1 generator in only 1 shock absorber, and using only 23% of the force generated by the weight of the vehicle at 1G, with an efficiency of 75%, clearly under normal conditions of use, will depend on the mix of external conditions as ascents, descents, state of the terrain, and atmospheric factors such as wind for, against, rain, etc ... and therefore, clearly, the most cautious thing is to speak of GREAT INCREASE OF THE AUTONOMY OF THE ELECTRIC VEHICLE and not of unlimited autonomy, although with these numbers it is probably close to getting it.
But in any case, tomorrow, when all the vehicles are electric and the energy demand increases, we will have a problem of energy deficit and as a consequence of the aggravation of the important climate change problem, and even if our system managed to "only" save a 40% or 50% of these needs, would surely be one of the inventions of the century.
We must also take into account that all the advances and research being done are focused on improving the batteries in terms of having more capacity and recharging more quickly, but this does not solve the problem, because they will need to be recharged as well. But these important improvements of the batteries, benefit even more our generator system by having more time to charge batteries that will be charged more quickly.
Evidently the improvement in the batteries and our generator system are the complements that give the ideal solution to make the change to transport with electric vehicle in a definitive way. |
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