Bi-directional converter targets energy storage & recycling

30th March 2015
Siobhan O'Gorman

A bi-directional converter, suitable for energy storage systems with rechargeable batteries, has been introduced by TDK-Lambda. The EZA2500-32048 is a 2500W digitally controlled, compact 1U power supply that can automatically change conversion direction from high voltage dc sources, powered by solar or wind, to 48VDC batteries and vice versa.

In addition to small to medium sized energy storage, applications also include lithium-ion battery testing as well as the utilisation of regenerated energy from robots, cranes, autonomous ground vehicles and lifts. For example, the EZA2500 can replace the large power resistors currently used for lift braking and instead use that previously dissipated energy to charge batteries. That storage can then be used to either provide peak power for high torque demands or as battery back-up for power cuts.

The converter operates from, or supplies, either 36-60V or 300-380V DC voltage with maximum currents of ±52A or ±7.8A, respectively. The output voltage and current can be programmed and monitored using the RS-485 communications port. For larger systems, multiple units can be operated in parallel by setting the unit to ‘droop mode’ current share via the RS-485 interface. A variety of alarm signals are also accessible, as well as remote on/off and under/over voltage functions. The EZA2500 will operate at full load in an ambient temperature of -10 to +40°C.

Internally, the twin DC/DC converter design enables continuous transitional switching between charge and discharge states to maintain the stability of the bus voltage. Operating efficiencies of up to 94% are achieved with the use of full digital control. The converters are isolated: 3kVAC from the high voltage (grid) to low voltage (battery) input/outputs, 2kVAC from grid to ground and 500VAC from battery to ground.

The dimensions for the EZA2500 are 43.6mm (1U) high, 423mm wide and 400mm deep. The converter, which carries the CE mark for the LVD and RoHS2, is UL/CSA 60950-1 and EN 60950-1 certified. TDK-Lambda offer the device with a five-year warranty.

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