(A) calculate the maximum power of the traction motor when constant acceleration
ID: 2072724 • Letter: #
Question
(A) calculate the maximum power of the traction motor when constant acceleration is designed. (B) Suppose the motor and controller loss can be neglected (100% efficient, or motor input = motor output), calculate the maximum power (kW) rating of the battery pack. (C) Suppose the vehicle needs to be on battery only mode for at least 20 seconds at maximum motor power, maximum battery energy can be used is 25% change of SOC (for example, SOC change from 95% to 70%), or 25% of the rated battery kWh can be used, calculate the energy rating (kWh) of the battery needed. [3] For a series HEV. The engine/generator set can deliver optimum 45kw of output. Maximum cruising speed is 160km/h. Maximum acceleration is 3.3m/s 2 and constant acceleration is assumed for all speed ranges. Total resistive force (gravitation, rolling and aerodynamic) counts 15% of the total acceleration needs. Vehicle mass is 1000kg. Grade is zero. [30 ptsl (a) Calculate the maximum power of the traction motor when constant acceleration is designed. (b) Suppose the motor and controller loss can be neglected (100% efficient, or motor input- motor output), calculate the maximum power (kW) rating of the battery pack. (c) Suppose the vehicle needs to be on battery only mode for at least 20 seconds at maximum motor power, maximum battery energy can be used is 25% change of Soc (for example, SOC change from 95% to 70%), (or 25% of the rated battery kWh can be used), calculate the energy rating (kWh) of the battery needed.Explanation / Answer
V= 160km/h = 160*1000/(3600)= 44.44m/s
acceleration = 3.3m/s2
a) Force Fte = mass × acceleration= 3300 N
fresistive 15%of 3300
total force = 3300+ 15% of 3300= 3795
Final power at constant acceleration= Ftotal * V = 3795*44.44= 168.649 kW
b) Motor losses are neglected then f will be only 3300
peak power= Fte*V = 3300*44.44 =146.656 kW
c) time = 20s
Energy required = mass × V2 /2 = 1000× (44.44 m/s)2 /2 = 987456 J
25% of energy= 246864
Rating kwh = Energy/Time = 246864 / 10 = 24.686 kW
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