| The electric scooter is widely used by the elderly because of its simple structure and convenient operation,and its development is also relatively rapid.It is of great significance to study the endurance of electric scooters to contribute to environmental protection and energy conservation.Based on the analysis of the influencing factors of cruising ability of the electric scooter,this paper proposes to use DC/DC converter and energy recovery to improve the endurance of the electric scooter.The main research work of this paper is as follows:(1)Calculate the cruising range of the electric scooter and analyze the factors affecting the cruising ability of the electric scooter.In response to these factors,several methods for improving the endurance of electric scooters have been proposed.After comparative analysis,the final choice is to improve the cruising ability of the electric scooter by optimizing the driving mode of the electric scooter and recovering the braking energy of the electric scooter.(2)Due to the modulation mode of the three-phase full-bridge circuit using the H_PWM-L_ON(upper bridge pulse width modulation and the lower arm continuous conduction),the drive circuit and the motor generate a large amount of loss,so a brushless DC motor drive system based on DC/DC converter is designed in this paper.After analyzing the DC/DC converter,the interleaved parallel two-phase bidirectional half-bridge circuit is selected as the bidirectional DC/DC converter.The working mode of the two-phase bidirectional half-bridge circuit is described,and the synchronous rectification technique is proposed to reduce the loss of the circuit.The three-phase full-bridge circuit in the brushless DC motor drive system adopts H_ON-L_ON(only commutation,no pulse width modulation);the speed regulation strategy of the brushless DC motor is designed.Simulation results show that this method can effectively reduce switching loss and motor iron loss.(3)In order to recover the braking energy of the electric scooter,several kinds of electric scooter braking methods are analyzed,and the energy feedback braking mode is selected.The full-bridge modulation mode and half-bridge modulation in energy feedback braking are compared,the half-bridge modulation method is selected as the modulation method of energy feedback braking;the process of half-bridge feedback braking is expounded,and the synchronous rectification technology is proposed to reduce the diode free-wheel loss;the limiting conditions of feedback braking are summarized,The braking current constant mode is used as the control strategy for the electric feedback brake of the electric scooter.(4)In order to verify the improvement effect of DC/DC converter-based brushless DC motor drive system and electric scooter energy feedback brake on the cruising ability of electric scooter,the hardware circuit and software flow of STM32F103RCT6 as the main control chip are designed.Through comparison experiments,it can be seen that the method described in this paper is 12.7% higher than the traditional driving method when the battery is 8.8Ah and the driving speed is 6km/h,which verifies the effectiveness of the method described in this paper. |
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