The power for an electric vehicle (EV) is usually supplied by a series-connected battery strings. The life expectancy of the batteries will affect the economical development of EV that leading to the public acceptance. Conventionally, the charging and discharging processes are conducted on the whole battery strings that will experience an unbalance charging due to the distinct characteristics of each battery in the battery strings. An unbalance charging not only can seriously reduce the life expectancy of battery, it also will result in insufficient usage of electric power. In order to resolve the problem stated above, the development of a battery equalization charger becomes an important research topic. With the aid of battery equalization charger, each battery will experience a balance charging process and obtain the equally energy charging regardless the different characteristic of each battery. In this paper, an equalization charger based on positive/negative pulse technology is proposed. The positive pulse current is utilized to charge the whole battery strings and the negative pulse current will extract some energy from the battery strings that will store in the energy storage components. According to the energy distribution among the batteries, a transformer utilizes the energy from the energy storage components to redistribute the energy within the batteries that is leading to the balance charging process. The proposed equalization charger is composed of a DC-to-DC converter and a multi-winding transformer. This simple structure of proposed equalization charger comes with a simple circuitry and provides the benefit of a low cost devise. An experiment test is conducted based on the same operational conditions on battery strings with or without the equalization charger. The results show that the proposed equalization charger can achieve the effectiveness of equalized charging, provide a better charging performance, and effectively control the battery temperature. This provides an effective way to extend the life expectancy of battery strings.
It is the purpose of this paper to introduce the advantages of Grey predictor controllers. We adopt grey prediction to obtain simple and effective estimated values, and, with the aid of first-order low-pass α Filter, greatly improve the accuracy subsequently used in the prediction for system response. The result will be in turn used to predict error and furthermore automatically adjust the parametrical values of PID controller, and accordingly will be able to deal with the possible variation of system responses at the very first stage. It can not only actively promote the responses efficiency of transient response, but also passively prevent disturbance. As a matter of fact, the highest demand of "plug in and play" can be met without any need to adjust the parameter. This paper will give a detailed specification of the system structure, the design, and the concept, as well as prove the modulation function of Grey predictor controllers in unit step response by means of Matlab program simulation and mathematical argumentation. In transient response, it will effectively fasten rising time, shorten settling time, and oppress overshoot; meanwhile, in steady state response, it is able to reduce steady state error to zero and achieve what traditional PID cannot perform.Index Terms-Grey Predictor Controllers, Low-pass α Filter, PID Controller, Plug in and Play.
The petrochemical industry is relatively strict regarding safety rules in the workplace. The workplace involves high-risk categories that are intolerant of human error. Especially in the current situation with COVID-19, concerns regarding prevention and safety in the workplace have increased. In light of this pandemic, the company must know whether all employees recognize the implementation of COVID-19 prevention. In addition, employee awareness of safety grounded in the affective domain of human thought is lacking. This study investigates the safety attitudes and COVID-19 prevention in the workplace based on the affective domain of employees. A survey questionnaire based on the Likert scale was utilized to collect data from 618 employees in the petrochemical industry. Descriptive analysis and analysis of variance were used to examine the data. The results reveal that employees in the petrochemical industry have a positive degree of responses to COVID-19 prevention, safety attitudes, and the affective domain, regardless of employment characteristics such as gender, age, position, and work experience. This study concludes that a positive affective domain of employees is followed by a positive safety attitude; thus, effective COVID-19 prevention was established in the workplace based on the perspectives and attitudes of the employees.
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