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Rectiverter - AC&DC Three Port Converter

Background

In many remote equipment cabinets in a wide array of industries, there is a need for multiple power inputs, either both AC and DC, or multiple voltage levels. 48 VDC is the most common voltage used for telecom equipment. For industrial equipment, a variety of difference DC voltages are used - from 24 VDC to 220 VDC depending on the different applications.

In addition to the DC load, there could be equipment installed that requires an AC feed, which can be resolved in serveral ways. One option for providing AC power is to install a small uninterruptible power supply (UPS) alongside the DC rectifier. However, this option requires two independent batteries for the AC and DC loads that need to be maintained.

A second alternative is to include an inverter withing the DC system to feed the AC equipment. This option has the advantage of needing only one battery for both AC and DC equipment.

Different inverter technologies are available, with feeds from DC or from both DC and AC. The most common solution is to use inverters that feed from the DC side, connected to a static bypass switch that activates in the event of an inverter failure or overload on the AC side.

The Rectiverter Concept

The Rectiverter is an Eltek concept that combines both DC and AC feed into one common unit, as a three-port converter. During normal operation, the Rectiverter feeds both AC and DC loads at the same time (with input feed from AC).

In the case of an AC (mains) power failure, the DC port has a bi-directional function that feeds the built-in inverter instead of the DC load, while the feed of the DC loads is taken over by the batteries.

This feed transfer to the built-in inverter from AC to DC is a seamless operation, with no interruption on the AC load.

The Rectiverter can also be used as a pure inverter feed from DC (without any connection to AC). To provide such support, a rectifier needs to be added in front of the Rectiverter, in order to prevent discharge of the batteries during normal operation.

Further, the Rectiverter can be used as a pure rectifier by disabling the AC output port. This makes the Rectiverter a very flexible module capable of feeding both AC and DC loads at the same time, or only the AC or DC load.

Suitable Industry Applications

Combined DC and AC Load Distribution

 

 

In many telecom and industrial applications there is equipment that can't be supported by DC power. Also when there is a long distance between the power source and the feed equipment, it could be advantageous to distribute 230 VAC instead of 48 VDC, to reduce power loss from the source to the feed equipment.

To feed the AC equipment, a small UPS or an inverter is usually installed in parallel to the DC power source. With the Rectiverter, it is possible to feed the AC and the DC loads at the same time. Depending on the split between AC and DC equipment, the Rectiverter can be set up according to the required AC or DC load.

In large central offices where the DC load is generally much higher than the AC load; the Rectiverter DC port can be paralleled with Eltek Flatpack2 rectifiers on the same DC bus and the Rectiverter DC output will share current between the connected rectifiers.

Example of Suitable Applications

     - Radio base stations in combination with AC feed remote radio heads (RRH)

     - Central offices in combination with other AC equipment

     - Power utilities switch tripping in combination with AC feed SCADA systems

     - Rail signalling and comunications

     - Rail control centers, with combination of DC and AC loads 

Combined DC and AC Load Distribution

 

 

 

 

 

 

 

 

 

 

 

 

In combination with Eltek solar and wind converters, the Rectiverter can be used in remote off-grid alternative energy applications. With no AC connected to the Rectiverter it will operate as a pure inverter, but with the possibility of connecting a generator to the AC input port, if that is needed.

In case a generator is uesed for recharging batteries during the night, no additional rectifier needs to be added, as the bi-directional DC port will work as a rectifier when AC input is available.

The Rectiverter is also useful in "micro grid" or "hybrid house" solutions when alternative energy provides a mini grid for remote areas without connection to the public power grid. Renewable energy sources can be used to supply electricity through an off-grid power system with flexible management of energy production and consumption.

Examples of Suitable Applications

     - Off-grid usage in combination with Eltek solar or wind conveters

     - Micro grids AC (and DC) solar converters, batteries, etc.

     - Residential AC+DC distribution in a "hybrid house"