Case of Study of the Electrification of a Tractor: Electric Motor Performance Requirements and Design

Abstract

The focus of this paper is the potential electrification of specialized agricultural tractors involved in vineyards and orchards. This category of machinery has not received research attention to date; however, regulations are encouraging lower emissions and higher efficiency, requiring the adoption of new technologies. Traction makes up only a limited part of this application, and the working cycle is not trivial; therefore, the design of the system is not straightforward. This study takes advantage of experimental measurements carried out under real operating conditions on a traditional specialized tractor, which was chosen as performance target. The performance requirements of the hybrid powertrain components are investigated, with particular focus placed on the electric motor. According to the dimension constraints, the design of the electric motor is carried out considering the requirements in terms of its thermal-equivalent torque and overload capability. The results are validated through a detailed thermal simulation under real duty cycles.

A Design of an Unmanned Electric Tractor Platform

“…) × 0.12 × 6474.6 × 18 = 4.8 kW (7) where η = 0.81 is the efficiency of the power transmission of the whole vehicle, and V 1max = 18 km/h is the highest vehicle speed during transportation.…”

“…In addition, the tractor was equipped with a rotary converter, which could tow other agricultural implements [6]. Since the 1990s, the control and battery technology have developed rapidly, and the performance of electric tractors has gradually improved, and there is more research devoted to the development of electric tractors and their electromechanical related design [7][8][9].…”

Electrification of Agricultural Machinery: A Review

“…Instead, since in many working conditions the machines are subjected to a varying torque demand, it could be a proper choice to set a lower rated torque, while the peaks could be fulfilled with an overload torque. Yet, in this way, the EM must be designed to have a proper overload capability, in order to supply the peaks for enough time, without electromagnetic or thermal To do this, in [84] the thermal equivalent torque method was adopted. Then, the authors designed a six-pole liquidcooled SPM with 10 kW rated power (40 Nm @ 2600 rpm).…”

Electrification of Compact Off-Highway Vehicles—Overview of the Current State of the Art and Trends

“…Examples of this trend include the various projects on the hybridization of compact agricultural tractors [18,19,136,137], where the main objectives are the possibility of downsizing the ICE and addition a pure electric mode, which could be useful for less demanding tasks or for use inside greenhouses. However, even if there are some cases of hybrid compact vehicles below 56 kW, like the hybrid skid loader studied in [20,21], their higher efficiency does not justify their higher upfront cost.…”