The AX8820 universal regenerative unit from Beckhoff is used to feed regenerative energy back into the grid. It is suitable for use with the AX8000 multi-axis servo system, AX5000 digital compact servo drives, and third-party devices. The energy is regenerated sinusoidally, preventing the grid distortions that are common with block-shaped regeneration.
The AX8820 regenerative unit is designed for a nominal supply voltage of 400 to 480 V AC, nominal output of 7 kW, and a maximum DC link voltage of 848 V DC. For effective energy management, the regenerative energy is initially stored in the DC link. The AX8820 only starts feeding power back into the grid just before the overvoltage threshold of the connected devices is reached. Several AX8820 regenerative units can be operated in parallel to optimally adapt the regenerative power to the needs of the machine.
No communication via EtherCAT is required to carry out energy recovery. However, extended parameterization – to adapt the voltage levels to the connected devices, for example – is possible via EtherCAT. With the help of the extended diagnostics via EtherCAT, the current regenerative energy can also be analyzed. The online data can be used to record the timing of the machine processes. This means that an investigation to see whether the efficiency of the machine can be increased by staggering the machine processes can be performed.