| Hazy weather occurs frequently in China,which leads to the community focus on vehicle exhaust emissions.The electric car as a green,economical transportation means is widely used.Battery is the power source of electric vehicles.Lithium-ion batteries are the most potential secondary batteries now,with which the efficient and safe battery fast charging strategy is researched implemented in the present study.Typical rapid charging methods remain to be further improved in the relations of coordinating charging efficiency and eliminating polarization.In order to save energy effectively,improve the charging efficiency and shorten the charging time,this paper used negative pulse depolarization method to effectively remove the polarization,and chose the energy supply circuit to effectively use the energy.The specific research contents are as follows:1.This paper mainly studied how to improve the efficiency and energy utilization of lithium ion battery charging method.And elected the lithium-ion battery as a research object,analyzed its working principle,charge and discharge characteristics and influencing factors.The paper studied the mechanism of polarization phenomenon,elimination methods and principles.Studied the advantages and disadvantages of the existing fast charging method,and the difficulty of realizing high current charging to improve the charging efficiency,that is,the use of high current charging will make the polarization more serious,the pulse charging method is analyzed emphatically.2.Polarization will reduce the battery charging efficiency,shorten the battery life.In order to solve the problem that depolarization effect is not obvious in the existing fast charging method,this paper adopted the instantaneous negative pulse depolarization.In the battery charging process,the timely suspension of charging,and the appropriate access to the discharge pulse can quickly and effectively eliminate a variety of polarization voltage,thereby enhancing the charging speed and efficiency.In this paper,fuzzy controller 1 is used to determine the degree of polarization through the gas point voltage and the battery capacity and surface temperature,that is,given the timing of negative pulse to add;fuzzy controller 2 is used to determine the width of the given depolarization negative pulse through the battery polarization and charge state and the temperature correction.Finally,the effectiveness of negative pulse depolarization is verified by comparison experiment.Compared with the traditional high current charging method,the power consumption of the battery is increased by 10.71% with the negative pulse charging method.Compared with the traditional constant current charging method,the charging time is shortened by 32.85% with the negative pulse charging method.3.In order to improve the energy utilization of lithium ion battery charging process,this paper used the feed circuit to store the power released by battery in the negative pulse discharge depolarization phenomenon to the capacitor,then feed to the battery when it is being charged.This paper drawn the circuit and analyzed the working principle.The experiment proved its validity and feasibility.4.Built the block diagram of pulse fast charging system,designed the main circuit,composing circuit and software achieving map,and finally built a battery test platform to test the function of fast charging system.Compared this method with the traditionalintermittent-positive and negative pulse charging method through the experiment,the charging time is shortened by 34%,the temperature rise by 13.6%,the charging efficiency increased by 1.4%.This study is suitable for the portable electronic equipment,electric vehicles,uninterruptible power supply and other systems,which the power batteries are used as energy storage devices. |
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