E-Mobility Engineering 017 l ECE Doosan electric excavators dossier l In Conversation: Matt Faulks l Battery testing focus l Battery Show North America 2022 report l Ariel Hipercar digest l Cathode materials insight l Thermal management focus

or repairs done on the motors and inverters either face to face or by fast shipping,” Van Hal says. “Not only would it take far longer with a US or Asian supplier, but even getting feedback would be limited by the time difference.” The DX165W Electric is powered by an EM-PMI375-T500 motor, which provides power ranging from 66 kW up to 158 kW at operating speeds from 1100 to 4000 rpm respectively. It weighs 172 kg, measures 368 mm long and 450 mm in diameter, and outputs up to 3400 Nm of static torque or 2500 Nm of dynamic torque. “On the DX165W we’re able to do all our lifting and traction with no more than 104 kW from the T500, with no difference for the operator in terms of the feel they get from their levers,” Van Hal says. “We could use more power to do jobs faster, but for now customers are fine with it.” The DX300LC Electric meanwhile uses Danfoss’ EM-PMI375-T800. This is a 428 mm-long, 450 mm-diameter, 210 kg machine that supplies 85 kW when running at 900 rpm and peak continuous power of 251 kW at 4000 rpm. Both e-motors are reluctance- assisted synchronous permanent magnet AC machines with six pole pairs in their stators and internally mounted rotor magnets, capable of up to 96% power efficiency, built using aluminium frames and ruggedised to IP65. Each motor’s shaft comes with an SAE-standard flange mounting to match the kind of connections typical of diesel engine shafts, which helps keep their integration into the Doosans straightforward. The motors are also paired with Danfoss inverters, with common coolant loops running between the motor and inverter. A water-glycol mixture is pumped at a minimum flow rate of 20 litres/minute and at a maximum pressure of 3 bar, with a specified operating temperature range of -20 to +70 ºC for the liquid. The powertrain risks becoming derated if either extreme is surpassed. Transmission and controls As mentioned, the downstream parts of the excavators’ drivetrains – their lifting arms, booms and buckets, as well as their traction systems – have been left largely untouched. The electric powertrain and cabin systems are generally closer to being drop-in replacements than requiring general overhauls of the machines, save for the aforementioned changes to the chassis from their diesel engines to warm their cabins, ECE uses electric heaters from Webasto (one per EV) to pipe heat in a liquid circuit around the operator’s station. Unlike the current compressor, that is an 800 V system. Here, however, Webasto adds that it has now developed and certified an 800 V air-conditioning compressor for ECE’s Doosans, and that these will be integrated in 2023, replacing the 24 V systems and hence eliminating the associated DC-DC and its power efficiency losses. Webasto also notes that future architectures of the construction EVs might use the heat of the battery packs to warm the cabin, thereby replacing the electric heater or allowing the use of a smaller one instead. “It is far easier to find 800 V compressors these days,” Van Hal adds. “They’re not as widely available as 300-400 V systems, but judging by the market trends we think 800 V HVACs will soon be the norm in heavy- duty EVs.” Powertrain While the electric DX165W and DX300LC can use the same compressors and heaters, since both house a single operator in their cabins with identical environmental requirements, the latter has a larger lifting arm and digging capacity as well as a greater overall mass, so it needs a much more powerful e-motor. Both machines use motors and inverters from Danish industrial group Danfoss. As well as being a European supplier, the company specialises in designing electric motors for battery-electric or hybrid powertrains in mobile work machines, buses and marine vessels operating in harsh environments and demanding applications. “Danfoss has its factory in Finland, and service partners across the continent, which means we and our customers can easily get maintenance A considerable thermal management system is needed to ensure the packs stay at 25-30 ºC, even while outdoors in the coldest winter climates 28 January/February 2023 | E-Mobility Engineering