E-Mobility Engineering 015 l EMotive Scarab off-road truck dossier l In Conversation: Giulio Ornella l Hall effect and magnetic sensors focus l Challenge of batteries for heavy-duty EVs l Alpha Motor Corporation digest l Automated charging insight l HVAC systems focus

including the ability to take future driving conditions into account. With multiple components interacting in feedback loops, HVAC systems are inherently complex, and their integration with powertrain thermal management adds to that complexity. Successful predictive control relies on accurate models of system behaviour and on knowledge of driver behaviour, which might be based on a profile or draw on a route plan for example, as well as the likelihood of the battery needing a fast charge en route. Independent measurements and comparisons show a possible saving potential of up to 50% of the current required average HVAC energy consumption, according to the HVAC, battery and charging systems supplier. Battery cooling during fast charging could be a major driver pushing towards predictive controls with integrated thermal management and HVAC systems in particular, the simulation specialist notes, pointing to a potential need for up to 10 kW for the process. It might be necessary to predict a fast charging event so that the system can heat or cool the battery in advance, so that the BMS will allow charging at the highest rate to begin as soon as the vehicle is plugged in. That might be a way of avoiding unnecessary complexity, cost and weight, he says, exemplified by the installation of two compressors for extra cooling capacity, which some vehicle OEMs have already enquired about. Integration implications Design and implementation of such closely integrated systems is challenging, and the practicalities can make attractive ideas hard to realise, the expert from the control software and hardware provider cautions. For example, liquid cooling is an option for traction inverters, but the design of individual systems depends heavily on the vehicle maker and the EV model. He notes that it is easy to imagine a heat exchanger with a blower integrated into the traction module’s cooling system, but a distributed cooling/heating installation could be easier to design, maintain and optimise for cost than a centralised one. He adds that implementing a ‘super- cooler’ that can cope with both the traction inverter and the passenger cabin is quite challenging. Similarly, a blower fan is feasible for a battery pack but a bit more complex if the batteries are spread around the vehicle, which they might be in a module-to-chassis architecture, for example. Our HVAC systems builder notes that integrated systems are attractive to vehicle OEMs and suppliers alike. OEMs benefit from lower engineering, assembly and component costs, along with optimised thermal management, while suppliers can gain a competitive advantage from going beyond offering components, modules and subsystems, and working with customers to manage trade-offs in terms of efficiency and cost. The challenge is to reduce the number of individual components, which reduces material and assembly costs for OEMs, while balancing the requirement for more complex controls and algorithms to meet the heating and cooling demands from multiple subsystems, he adds. Fluid working One of the fundamentals of integrated HVAC and thermal management systems that use liquids to move heat around is ensuring the efficient transfer of that heat between the different working fluids, which typically are water-glycol coolants or hydrofluorocarbon (HFC) refrigerants. The automotive electrification specialists stress that this requires compact heat exchangers that are optimised for efficiency in the most important operating modes, along with heating/cooling circuits with short and isolated ducting, and accurate control of the flow rates in the coolant and refrigerant loops to optimise the heat transfer. Although this is not a problem technically, it is not yet easy to offer generic solutions that are fully cost- optimised, the HVAC, battery and charging systems expert notes. While efficient, low-cost systems can be provided for vehicles built in large volumes and that have clearly defined applications, they are not yet available for mid- and low-volume applications. These need individual parts with higher costs and lower availability, although the company expects that situation to change in the near future. Positive Temperature Coefficient heaters have a number of advantages for localised heating, including their ability to be made in a wide variety of shapes and of flexible materials (Courtesy of Termico Technologies) 70 Autumn 2022 | E-Mobility Engineering