EM-PMI375 permanent magnet synchronous motor, EC-C1200 inverter, and MC050 motor controller, plus three 140-kWh batteries.
Danfoss engineers replaced the excavator’ s conventional swashplate hydraulic pump with the DDP180D pump / motor. The excavator’ s four primary services— boom, arm, bucket, and swing— are supplied through ten individually controllable outlets on the pump. These outlets are dynamically grouped through a ganging block, a digital distributor that reallocates capacity to the service requiring it. A dedicated valve operating as a hydraulic H-bridge was developed and applied to the boom function to allow independent metering, providing anti-cavitation, pressure amplification, and energy recovery during overrunning motions. Finally, the control system architecture was developed to provide real-time control of the hydraulic system, electric powertrain, and auxiliary subsystems.
To compare system performance before and after conversion, multiple tests were carried out, including JCMAS air grading and JCMAS air dig and dump( equivalent to ISO / AWI TS 11152-2). Compared to the baseline electric excavator, the Dextreme Max system reduced battery energy use by 49.2 % in air grading and 31 % in air dig and dump, with negligible impact on cycle time. Assuming a duty cycle of 30 % grading and 70 % digging, Dextreme Max would reduce battery power consumption by 35 % without significantly impacting work rate. This would result in 53 % longer operating hours with the same battery capacity as the
baseline machine, or similar runtime as the baseline with two battery packs instead of three.
“ The results of this testing highlight the potential of digital hydraulic architectures to overcome the obstacles in heavy-duty machinery electrification. Electric excavators offer excellent responsiveness, smooth control, a quiet cab environment, and zeroemission operation. With Dextreme Max, they can also deliver the runtime, productivity, and total cost of ownership advantages required for wider adoption, thereby accelerating the decarbonization of heavy-duty machinery,” said Alasdair Robertson, Senior Director, Digital Displacement, Danfoss Power Solutions.“ We are extremely encouraged by these results, but there is more work to do. Further gains are possible, and we will continue optimizing the system to maximize the energy savings and value for our customers.”
Danfoss Dextreme systems offer an incremental approach to implementation through three levels: Swap, Flex, and Max. Dextreme Swap involves a simple pump replacement, offering improved system control and more efficient operation. Dextreme Flex introduces flexible allocation of the Digital Displacement pump outlets, reducing flow distribution losses and further improving efficiency. The Dextreme Swap and Flex systems are commercially available, and this project has advanced the path to commercialization for Dextreme Max. To learn more, visit the Dextreme systems webpage.
For more information, visit www. danfoss. com
MACHINERY, AUTOMATION, CONTROL & ENGINEERING 5