E-Mobility Engineering 014 l InoBat Auto dossier l In Conversation: Brandon Fisher l Battery monitoring focus l Supercapacitor applications insight l Green-G ecarry digest l Lithium-sulphur batteries insight l Cell-to-pack batteries focus

“Of course, it’s a little tricky to manage everything precisely, as the heat produced by the powertrain will oscillate during operations, and then it can spike at the charger when you’re sitting still and recharging,” Aretino notes. “On top of that, there are considerable swings in ambient temperatures between the north and south of Italy that need to be compensated for. So we did a lot of testing to optimise our coolant management, including sitting the ecarry in the sun on the hottest days of the year with a high- power charge to stress-test the OBC, and doing repeated stop-start drives up and down hills to see what thermal problems the powertrain would encounter.” One liquid circuit runs between the batteries and cabin, given the similar temperature requirements between people and battery cells. Another runs between the inverter and OBC, as the powertrain generally alternates between the two, and both of them experience similar spikes during usage, creating similar requirements in the liquid’s pressure and control algorithms. While water is used as the cooling medium in these, an oil-cooling system keeps the motor from overheating; Aretino remarks that using oil enables the use of a smaller motor with a higher power density. “Using a small e-motor is important for us,” he says. “As a light commercial vehicle, we can’t make the ecarry too tall, long or wide to accommodate an oversized motor.” Automotive networks and processors All internal comms between subsystem ECUs are delivered over a CAN bus, with a dedicated interface for body assemblers to use if they opt to integrate their own electronics and connect them to the bus; this also prevents them interfering with existing data links between core subsystems. The network connects all of these lower- level controllers to a single VCU that filters driver inputs through to the powertrain and cabin systems. “Our VCU and all the lower-level ECUs are controlled by processors from NXP,” Aretino says. “While NDAs prevent full disclosure here, I can say that the VCU uses a 32-bit processor, and while we could have run everything on the VCU, we opted to split the control modules across the lower-level ECUs throughout the low-voltage network for better safety. “And as well as delivering subsystem data to the driver’s LCD interface, telemetry is also sent via an onboard IoT device to a cloud system so that the fleet operator can remotely monitor and record the performance of every ecarry vehicle in real time. We developed the cloud computing and comms software in-house, as we expect more and more clients will use it, and to request advanced cloud features such as teleoperation of the vehicle’s controls and charging systems.” This will be especially important for large fleets, as setting limits on charging rates ad hoc will allow end-users to reduce their energy bills by enabling the bulk of charging to occur during the least expensive time at night. As a final note, Aretino adds that the network for power delivery from the battery to all the other high- and low- voltage systems is controlled via a custom power distribution unit, developed in- house. Designing around this single point of power coordination is intended to simplify the process of swapping new components in and out of the EV, enabling modularity of the ecarry’s powertrain. Future plans This powertrain and software modularity is expected to ease the process of updating the ecarry’s subsystems as new e-mobility technologies come onto the market. “We expect to update quite a lot as time goes on – for example, we don’t expect to stick with a 400 V architecture forever, and most of the powertrain’s components are removed by just unscrewing a few fasteners,” Aretino says. “We also expect EV tech to get smaller and more power-efficient in the years ahead, especially regarding advances in battery chemistries.” Speci ications Green-G ecarry 400 V battery-electric light commercial EV Permanent magnet AC motor Single-motor rear-wheel drive NMC battery cells Size: 5.64 x 1.93 x 1.59 m Gross weight: 3500 kg Maximumpayload: 1700 kg Maximum range: 250 km Maximum speed: 80 kph Maximum torque: 380 Nm Maximumpower: 90 kW Nominal power: 60 kW Maximum energy storage: 70 kWh Subsystem data is delivered in real time to the LCD interface and to a cloud system for the Åeet operator to monitor and record for optimising maintenance Summer 2022 | E-Mobility Engineering 55 Digest | Green-G ecarry