Tham khảo tài liệu 'electric vehicles modelling and simulations part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | DC DC Converters for Electric Vehicles 319 Where Vout the output voltage AILmax the inductor current ripple F the switching frequency. ILmax the maximum input current AVout_max the maximum output voltage ripple. Table 1 shows the specifications of the converter. The inductor current ripple value is desired to be less than 5 of the maximum input current in the case of interfacing a Fuel Cell. A ripple factor less than 4 for the Fuel Cell s output current will have negligible impact on the conditions within the Fuel Cell diffusion layer and thus will not severely impact the Fuel Cell lifetime Yu et al. 2007 . A V out_max Output voltage ripple 1 of Vout 4 V Vout Output voltage 400 V F Switching frequency 20 KHz ILmax Inductor current 250 A AILmax Inductor current ripple 5 of ILmax A Table 1. Standard boost DC-DC converter parameters Modeling and control The output voltage is adjustable via the duty cycle a of the PWM signal switching the IGBT as given in the following expression Vout Vin 1 - a 29 The input voltage Vin is considered as constant 200V . The inductor and capacitor resistances are not taken into account in the analysis of the converter. The converter can be modeled by the following system of equations T diL . X vin dt 1 - u v ut iL 1 - u C dr i ut 30 This model can be used directly to simulate the converter. By replacing the variable u by its average value which is the duty cycle during a sampling period makes it possible to obtain the average model of the converter as illustrated in the following system of differential equations diL vin dt 1 - a v ut ii 1 - a c dr iout 31 320 Electric Vehicles - Modelling and Simulations Current control loop The current control loop guarantees limited variations of the current trough the inductor during important load variations. The inductor current and voltage models are given by Equation 32 and Equation 33 respectively. IL s LsV s - 1 - a s Vout s 32 VL s Vin s - 1 - a s VMt s 33 To make it simple to define
