Unit installed as a separate component between the power supply unit and the inverter of the servo system and absorbs the regenerative energy. Oliver Endres reports
Mitsubishi Electric’s Energy Assist Unit is an intelligent solution for feeding regenerative energy from servomotors over 30 kilowatts back into the system so that it can be made usable again and ultimately reduce energy peaks significantly.
This is the a solution for tapping into the energy and cost-saving potential of machines with high energy consumption.
The Energy Assist Unit is installed as a separate component between the power supply unit and the inverter of the servo system and absorbs the regenerative energy which is generated upon braking of a servomotor.
In the process, the system recognises the renewable power and stores it in the capacitor bank. If required, the Energy Assist Unit makes the stored energy usable by helping to feed it back to the inverter.
Oliver Giertz, Product Manager Servo/Motion/Robot, Mitsubishi Electric Europe BV, explains: "As the Energy Assist Unit makes regenerative energy usable directly in the machine rather than just feeding it back into the electrical power supply system, the amount of basic current required will be reduced.
“As a result, energy peaks can also be reduced which represents another massive benefit for the user since he will then be able to adjust his existing contract with his electricity supplier. Subsequently, the contract will be determined based not only on the total annual energy consumption but also on the energy peaks calculated. Ultimately, users will be able to save money as a result."
The way that regenerative energy is used differs according to the type of system in each case. As a rule, in smaller systems regenerative energy is converted into heat by means of a braking resistor and not made usable first at all. In larger systems, the energy is frequently fed back into the electrical power supply system.
However, this more environmentally-friendly alternative does not reduce the total amount of energy that the user takes from the electrical power supply system and the electricity costs incurred will remain the same.
"The intelligent Energy Assist Unit controls the voltage in the servo controller automatically and independently directs the regenerative energy into the capacitor bank and from there back into the inverter. So the amount of basic current required and ultimately energy peaks too are reduced significantly,” explains Oliver Giertz.
The Energy Assist Unit is particularly suitable for machines with a high energy consumption which continually carry out the same movements such as injection moulding machines or large presses, for example.
Besides the Energy Assist Unit (MR-EAU100K4), the solution also includes other Mitsubishi Electric components including a PLC (QnUDV) and a motion controller (Q172DSCPU) on an iQ Platform as well as a converter unit (MR-CR55K4), a drive unit (MR-J4-DU37KB4) and a capacitor bank (MR-BC3014). The solution can be operated intuitively by means of an HMI from the GOT2000 series.
Oliver Endres is European Product Manager Energy / LVS / Inverter, Mitsubishi Electric Europe BV, Factory Automation European Business Group.