High Power Density Enables Retrofitting of Redundant Power Sources

May 9, 2018

A manufacturer of flow meters was upgrading the design of one if its products to improve accuracy and reliability. As the product was fundamental to safety, they wanted to add a back-up 48V supply using a battery, which would take over in the event of the main AC power source failing, as well as requesting a lighter product to simplify installation.

Flow meters need to provide precise and fast measurement, which requires conducted and radiated EMI to be minimized to avoid impacting the accuracy of the sensor. Adding to the complexity of this design, all the new and enhanced functionality was required to fit into the same case as the previous model.

industrial flow meter whiteboard

Industrial Flow Meter Solution (click to enlarge)

The customer used the Power Component Design Methodology to architect a solution that made use of Vicor power components. An AIM and PFM provided the AC front end, with a DCM used to regulate the voltage to the supply.

The AIM and the PFM provide an effective, low-noise AC-DC solution. The VIA packaging technology allows the PFM to be mounted on the equipment’s casing, eliminating the need for additional heatsinking to reduce the size and weight of the power system.

The DCM provides a particularly flexible solution to generate a regulated 48V rail from either the AC supply or the battery. They are isolated converters, offering up to 1% regulation and their wide input range (36V – 75V). This means the DCM continues to power the system even when the battery is significantly discharged, resulting in a lowered output voltage. With DCMs weighing just 24g and minimizing space requirements due to their very compact ChiP packaging technology, they helped the customer achieve their space and weight targets.

Another benefit of the DCMs is that their zero-voltage switching reduces the radiated and conducted EMI. This simplified the filtering required to avoid interference affecting the sensor, resulting in a smaller and lighter filter.

DCMs offer high efficiency of up to 93%, which is consistent across the operating voltage range. This allowed a longer period of operation from the same battery, increasing the time that the sensor will function during an AC power failure, as well as reducing the need for heatsinking.

The high-density power components used in this design enabled the customer to develop the solution, both for the AC-DC and the 48V battery input, in a footprint of just 64cm2, easily fitting into the existing flow meter case. With the total weight of the PFM and DCM just 172g, these components also enabled the design team to meet their weight targets.

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