The project required the construction of a system for a three-storey 30-meter high building with a throughput of 85 pallets per hour. Moffett needed an automated storage system to lift and lower pallets which weigh over 1500kg that would function in temperatures ranging from -25°C to +40°C. They approached Technidrive, who contacted WEG to provide them with an 11 kW electric motor, a variable speed drive (VSD) and corresponding programming software.
WEG's VSD at the heart of this technological feat
The VSD, also known as an inverter, allows the system to accelerate and decelerate faster and to automatically correct the cart's stability according to its weight, and thus keeps it passing along smoothly at the correct level. Technidrive also took into account the regenerative energy, i.e. the energy that returns to the inverter. When the inverter controls the speed of the lowering elevator, energy is generated back in the motor and then returns to the inverter in the form of DC bus voltage and needs to be dissipated in a break resistor or burned off as heat. Technidrive therefore increased the size of its shutdown resistors and added thermal protection to ensure that no overheating problems would occur from the regenerative energy.