Introduction
Environmental friendly agricultural machinery means the technology used in agricultural machines that has no effect on environmental issues such as air pollution, water pollution, soil pollution, sound pollution and so on. The enormous environmental pollution is occurred by combustion engines. Stone (1991) reported that internal combustion engines emit almost 1.1% pollutants. Johnson et al. (2007) reported that agriculture contributes approximately 6.3% of greenhouse gas emissions and mentioned that the reduction of harmful emissions is one of the solutions by decreasing the usages of the combustion engine. On the other hand, natural resources like oil and gas are limited and dramatically decreasing for high world demand. According to the report of Global Energy & CO2 Status Report, approximately 1.3% of global oil demand rose in 2018 than in 2017 and oil prices are also increased by almost 30% in 2018 than in 2017. Therefore, it is important to introduce environmental-friendly technology instead of the combustion engine.
Several researchers and manufacturers are applying electrical energy to the vehicles for considering environmental pollutions and fuel efficiency. Emadi et al. (2008) developed a layout of an electric or hybrid vehicle that is environmentally friendlier and a higher fuel economy. The operating principle for a RHINO, which was applied in a 21-ton electric excavator system was analyzed and measured the dynamic responses and the pressure loss (Kim et al., 2015). Bawden et al. (2014) designed the small robotic farm vehicle (SRFV) for broadacre agriculture. Gonzalez-de-Soto et al. (2016) used a hybrid energy system in a robotic tractor for precision weed and pest control in agriculture and also compared with the exhaust emissions of the combustion engine. The results found that the emissions reduced almost 50% in a hybrid energy system tractor. Also, an electric-driven control system was developed for a precision planter to avoid the poor planting quality and low traveling speed (He et al., 2017). Mousazadeh et al. (2010) applied the battery technologies for hybrid electric tractor and analyzed the environmental life-cycle effects and costs. Kim et al. (2015) also developed a 20 kW capacity hybrid power system for agricultural machines, which was attached to a multipurpose cultivator to increase efficiency. It was found that the CO and NOX emissions were reduced by 36-41% and 27-51%, respectively. The fuel consumption of the hybrid engine vehicle (HEV) was almost 36% less than that of a combustion engine. Lee et al. (2018) analyzed the power and measured the current of the developed electric drive transplanter. Therefore, the purpose of this study is to develop a user and environmentally friendly electric transplanter for greenhouse and analyze the power requirement for the field operations.
Materials and Methods
Power flow of an electric transplanter
An electric driving transplanter was developed by replacing engine driven multipurpose transplanter by battery and motor. The power flow of the multipurpose transplanter is divided into three parts: one is power generation part (Motor and battery), second is driving part (Driving wheel) and finally planting part (planting hopper). Electric power is generated by operating the motor and transmitted to the driving wheel through the clutch and driving shaft. Finally, the planting part consisting of a planting device and the hopper is performed by the belt-pulley. The schematic diagram of the power flow of the electric multipurpose transplanter is shown in Fig. 1.
Specifications of an electric transplanter
A 1 kW motor should have installed to deliver power to the axle and driving wheel through the belt-pulley. The rated torque of the motor is 15 Nm @ 1800 rpm. The key components of the transplanter are shown in Fig. 2 and listed the specifications in Table 1. The rated current and PWM frequency of the inverter is 80 A and 10 kHz, respectively. A 48 V battery is also installed.
The measurement system and field operation
Motor driving current was measured by the current probe (TCP303, Tektronix, USA) and the measured data was stored using an oscilloscope (InfiniiVision DSOX- 3024A, Keysight, USA). The required power of the motor was calculated using 48 V, the battery rated voltage of the multipurpose electric transplanter, shown in Fig. 3 (a). The working distance and width of the multipurpose electric transplanter were 10 m and 120 cm. Soil particles were analyzed by USDA, resulting in medium sand conditions ranging from 0.05 to 0.25 mm in diameter. The electric transplanter was performed using two methods: planting conditions (26, 42, and 63 cm distance) and simultaneously driving and planting conditions. The statistical analysis, one-way ANOVA with planting distance and Duncan’s multiple range test (DMRT) at a significance level of 0.05 were used to analyze the required power by the SAS (version 9.4, SAS Institute, Cary, USA).
Results and Discussion
The lower planting distance is required the higher average and maximum current for only planting operation. However, the higher amount of average and maximum current is also required at the lower planting distance for simultaneous operations with speed. It is also found that the motor required power is reduced by 11% for planting operation when the planting distance increased by 62%. It is noticed that the motor required power is decreased by almost 10% for simultaneously operation conditions when the planting distance is increased by 50%. The results with ANOVA analysis are shown in Table 2.
The statistical analysis shows that the required power of the motor was a significant difference with the planting distance for only planting operation. Also, a similar significant difference was found for simultaneously operation conditions. However, there is no significant difference in the same planting distance of both experimental conditions.
Conclusion
This study was conducted for the development of an electric multipurpose transplanter for environmentally friendly and analysis of the required power for the field operation. The field operation was conducted in two conditions: planting operation conditions at 26, 42, and 63 cm planting distance, and simultaneously planting with speed was also performed at 26, 42, and 63 cm planting distance. The results show that both for the planting and simultaneous operations, the motor required power has a significant difference but no significant difference between each planting distance. Finally, it can be said that the multipurpose transplanter could be feasible for the farmers at high driving speed for higher planting distance.
