A Review of Drive Cycles for Electrochemical Propulsion

Abstract

Automotive drive cycles have existed since the 1960s. They started as requirements as being solely used for emissions testing. During the past decade, they became popular with scientists and researchers in the testing of electrochemical vehicles and power devices. They help simulate realistic driving scenarios anywhere from system to component-level design. This paper aims to discuss the complete history of these drive cycles and their validity when used in an electrochemical propulsion scenario, namely with the use of proton exchange membrane fuel cells (PEMFC) and lithium-ion batteries. The differences between two categories of drive cycles, modal and transient, were compared; and further discussion was provided on why electrochemical vehicles need to be designed and engineered with transient drive cycles instead of modal. Road-going passenger vehicles are the main focus of this piece. Similarities and differences between aviation and marine drive cycles are briefly mentioned and compared and contrasted with road cycles. The construction of drive cycles and how they can be transformed into a ‘power cycle’ for electrochemical device sizing purposes for electrochemical vehicles are outlined; in addition, how one can use power cycles to size electrochemical vehicles of various vehicle architectures are suggested, with detailed explanations and comparisons of these architectures. A concern with using conventional drive cycles for electrochemical vehicles is that these types of vehicles behave differently compared to combustion-powered vehicles, due to the use of electrical motors rather than internal combustion engines, causing different vehicle behaviours and dynamics. The challenges, concerns, and validity of utilising ‘general use’ drive cycles for electrochemical purposes are discussed and critiqued.

PEMFC Electrochemical Degradation Analysis of a Fuel Cell Range-Extender (FCREx) Heavy Goods Vehicle after a Break-In Period

“…Drive cycles are standardised driving data published in a speed vs. time format [8]. The dynamic load cycling endurance test was used to simulate 100 cycles of HGV urban driving, a distance of approximately 530 km, representing the break-in period of a vehicle.…”

“…The FCH JU protocol was created for FCEVs (non-hybrids) and utilises the NEDC drive cycle [15]. However, the NEDC cycle is primarily a light-duty vehicle (LDV) modal drive cycle and is now considered outdated and less representative of realistic driving representation when compared to a WHVC and newer transient drive cycles [8]. Transient drive cycles are usually collected based on real-life driving data [8].…”

“…However, the NEDC cycle is primarily a light-duty vehicle (LDV) modal drive cycle and is now considered outdated and less representative of realistic driving representation when compared to a WHVC and newer transient drive cycles [8]. Transient drive cycles are usually collected based on real-life driving data [8]. Figure 4 shows a comparison between WHVC Urban and the commonly used NEDC.…”

“…Scaled-down bench testing offers a controlled environment to simulate operating conditions and accelerate degradation processes, replicating the real-life driving dynamics of FCHEVs in a laboratory setting. A key aspect of the project involves the development of drive-cycle-based bench testing tailored to range-extender FCHEV operation, enabling characterisation of power division [8]. Power cycles can be computed from drive cycles to estimate the power consumption of a vehicle as whole.…”

“…Power cycles can be computed from drive cycles to estimate the power consumption of a vehicle as whole. These power cycles can then be divided into two or more separate drive cycles to simulate power division in a hybrid vehicle [8]. These divided power cycles can be scaled down to a cell level to facilitate cell bench testing in an electrochemical lab [8].…”