Simulating & Evaluating feasibility to integrate charging of 12V battery with 48V drivetrain for Dual Voltage 48V/12V Mild Hybrid vehicles
Examensarbete för masterexamen
Electric power engineering (MPEPO), MSc
Dual voltage energy storage systems have become common in mild hybrid vehicles due to their advantages such as increased stability and reliability of the system. They serve a viable solution for increasing demand of power for Mild hybrid vehicles. The dual voltage in mild hybrids contains two level of voltages; 48V battery is used for electrical drivetrain and 12V battery is used to power auxiliary system of the vehicles. The demand for power for these auxiliary systems is increasing due to additional safety systems implemented in the car and hence, it is crucial to have required level of SOC for 12V battery. In current system, this is achieved by a separate dc/dc converter unit to charge the 12V battery pack. But, this unit is quite bulky and costly and hence, it is required to find an alternate solution to charge the 12V battery without using a separate dc/dc converter. This thesis focuses on investigating on an integrated charger topology suitable to charge 12V battery for Mild hybrid Dual voltage 48V/12V system. It also checks the feasibility of the topology to charge the 12V battery continuously under three modes of motor operation; Motoring mode, Regeneration mode and idle mode. The work mainly focuses on developing a simulation model which can simulate different modes of motor for mild hybrid vehicle for charging the 12V. The motivation behind the thesis is to integrate the 12V charging with 48V drivetrain which will reduce the overall size and cost of the drivetrain system. The analysis is done based on charger efficiency and generation of ripple for the three modes of motor operation.
Elkraftteknik , Electric power engineering