Aerospace, Military and Defence
density of Vicor, so we can achieve top levels of maneuverability, performance and hover control with their components. This enables DPI tethered drones to lift more, fly higher, and fly faster.”
Communications data transmitted and received by RF radio equipment mounted on the tethered multirotor drone is relayed through the tether to and from the host vessel, allowing beyond-line-of-sight communication with surrounding unmanned support vessels. This communications architecture presents EMI challenges for the power delivery network (PDN) architecture. Given the critical role these drones play in maritime defence and surveillance applications, the integrity of communications data is of paramount concern.
Power architecture innovation To achieve these aggressive power challenges, DPI is leveraging Vicor Ultra High-Voltage (UHV) BCM VIA modules within the drones to enable high-efficiency
conversion (98 per cent) — only 2 per cent losses from 800V to 50V. Two sets of four UHV BCM4414 modules are co-located within two waterproof aluminum system enclosures
When deployed as an airborne RF antenna, the UMAR can extend ship radio line of sight from 8 miles to up to 30 miles.
and are board-mounted to the host PCBs in an architecture that allows the low-profile, flat-sided UHV BCMs to be cooled from both sides. The compact footprint and mounting versatility of the UHV BCMs were particularly valuable for DPI designers to achieve an extremely power-dense board configuration. The Vicor BCM4414 in a VIA package is a high-efficiency fixed ratio bus converter, operating from a 500 – 800VDC high-voltage bus to deliver an isolated 31.3 – 50.0VDC. Measuring a mere 4.35 x 1.40 x 0.37in (110.55 x 35.54 x 9.40mm), this ultra-low- profile module provides up to 776W/in3 power density while incorporating DC-DC conversion, integrated EMI filtering and PM Bus commands and controls in a chassis- or board-mount form factor.
The array of eight BCMs power the UMAR’s eight independent rotors, with the ability to share power among the rotors in parallel for increased redundancy. An additional onboard UHV BCM powers the avionics, autopilot and payload functionalities. The UHV BCMs provide the extreme power conversion density to help minimize the weight of DPI tethered multirotor drones, converting 800V to 50VDC in an extremely compact form factor. The high-efficiency UHV BCMs greatly reduced the heat dissipation within the drone’s avionics modules, which are sealed in aluminum enclosures to prevent moisture ingress from saltwater and rain. The avionics modules leverage a system of heat pipes and heat sinks for passive cooling when the drone is grounded on the host vessel. When it’s airborne, the spinning rotors provide additional active cooling.
A low-voltage-side-referenced PM Bus-compatible telemetry and control interface provides access to the BCM VIA
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There are eight Vicor UHV BCMs arrayed to power the DPI UMAR’s eight independent rotors, with the ability to share power among the rotors in parallel for increased redundancy.
configuration, fault monitoring and other telemetry functions. This PM Bus capability allows the UMAR operators to monitor system temperatures, voltage and currents in real time, which is particularly valuable in hot climates.
The integrated EMI filtering capability within Vicor UHV BCMs helped to minimize noise that might compromise RF communications between the drone and host or support vessels. Conducted EMI along the tether is an especially important factor for implementations of adjacent radio equipment, and UHV BCMs offer a very clean EMI signature with very few harmonics below typical EMI standard levels. A small available companion filter reference design outside the VIA package cuts conducted EMI levels to near noise-floor signature well below typical requirements.
The sky is the limit
In addition to its current trial deployments with the U.S. Navy, DPI technology is being evaluated by a host of government agencies, contractors and other entities. It has shown significant promise for additional applications like first-response disaster relief and large- area monitoring (public events, stadium security, etc.). Anywhere a hover-in-place communications and surveillance presence might be needed, DPI multirotor drones could be readily deployed.
With Vicor UHV BCMs at the heart of the UMAR systems, DPI is assured of a power- dense, thermally-adept power system for high-voltage power conversion from tether to drone. As DPI multirotor drone technology takes flight, we can expect to see many more of them on the horizon.
www.vicorpower.com Components in Electronics March 2022 15
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