Variable DC-link voltage powertrain for electrified mobile work machines

Electric powertrains in mobile work machines are able to increase the efficiency and the effectiveness of the work process. Conventional powertrains are operated at their limits and thus efficient electric systems are entering the applications of mobile work machines. A simple electric powertrain consists of an energy source attached to an inverter-fed electric machine. Adding a DC/DC converter to this powertrain enables an adjustment of the DC-link voltage to the operating point of the machine and increases the efficiency of the work machine. This paper addresses the dependencies of the DC-link voltage regarding to the powertrain losses. An electric powertrain is simulated and verified using measured test bench data. Especially the losses of the electric machine are examined and the correlation to the DC-link voltage is analyzed. The focus is on identifying relevant load cycles of mobile work machines and operating points to gain an efficiency benefit by adjusting the DC-link voltage.