Size, weight and power efficiency challenges

Commercial UAV companies compete on payload capability and flight time which are directly proportional to the size, weight and power (SWaP) of the UAV. A major contributor to a UAV’s size and weight is the power delivery network (PDN). Increasing the functionality, payload and range is made easier with a lightweight, high-density, high-efficiency DC-DC power delivery solution.

Efficient power delivery with reduced footprint and weight

Vicor power modules enable rapid deployment of DC-DC power conversion and power delivery across a wide range of voltages and power levels for both ground control and onboard systems.

The benefits of modular power

Industry-leading power density of 1000 W/in³

Industry-leading power to weight ratio of 16.7 W/gram

Up to 98% efficiency

Rapidly design and deploy PDNs

Vicor power delivery for UAVs

Tethered, aerial and underwater vehicles (UAV/UUV/ROV)

This class of unmanned vehicle is powered and controlled via a tether from a ground-based power source. High-voltage tether transmission of 500V to 800V allows for greater tether lengths and smaller cabling, enabling the drone to fly higher or travel longer distances underwater. The power delivery network (PDN) inside the vehicle must be capable of down-converting the tether’s high voltage with high efficiency and power density to not take up important payload space. Tethered drone applications typically require a 1 – 5kW ground power supply tethered to a rotor-wing UAV or UUV, and offer unlimited run time and greater control.

Power delivery network

Using Vicor BCMs such as the BCM4414, a power solution can be created that enables optimized system performance. The BCM4414 provides 1.8kW of power for either step-up or step-down conversion at 97%+ efficiency. At the ground station, the BCM4414 isolates and steps-down the rectified output from a single or 3-phase AC supply to 48V. A second BCM4414 steps-up the 48V to 800V for transmission across the tether. A third BCM4414 is used to step-down the 800V to 48V onboard the vehicle. The use of the BCM4414 allows the power system designer to dramatically reduce the size and weight of both the ground supply and UAV, as well as to dramatically reduce the diameter and weight of the tether itself. The end result is a much more flexible and capable system that can be easily transported to the operating location.

Downstream of the BCM4414, ZVS Buck regulators offer board-level designers maximum power density and flexibility for high-efficiency point-of-load DC-DC regulation. The integration of a high-performance zero-voltage switching (ZVS) topology increases point-of-load performance, providing best-in-class power efficiency up to 98%. ZVS regulators are highly integrated with control circuitry, power semiconductors and support components in a high-density LGA, BGA and System-in-Package (SiP).

Example Power Delivery Network for a tethered UAV

BCM4414

Fixed ratio DC-DC converter

Input: 500 – 800V

Output: 31.3 – 50V

Current: Up to 35A

4.4 x 1.4 x 0.4in

ZVS Buck regulators

Input: 12, 24 or 48V

Output: 1 – 16V

Current: Up to 22A

As small as 7 x 8 x 0.85mm

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Untethered UAV

This class of UAV relies on battery, fuel cell or solar power, which puts greater demands on tradeoffs to meet range and payload performance specifications. These power sources also deliver widely varying or nonlinear output voltages that are handled better with power conversion and delivery solutions that use non-traditional topologies instead of the standard PWM (pulse width modulation) techniques and are far better at meeting the very demanding power requirements.

Power delivery network

ZVS Buck and Buck-Boost Regulators offer board-level designers maximum power density and flexibility for up to 98% efficient point-of-load DC-DC regulation. These high-performance zero-voltage switching (ZVS) topology regulators are integrated with control circuitry, power semiconductors and support components. They support single wire current sharing for higher power capability in a high-density LGA, BGA and System-in-Package (SiP). The high switching frequency of the ZVS Regulators reduces the size of the external filtering components, improving power density while enabling fast line and load dynamic response. The ZVS series offers buck regulators for 12V_IN, 24V_IN and 48V_IN nominal systems. All devices within their respective series share the same footprint.

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Example Power Delivery Network for an untethered UAV

ZVS Buck regulators

Input: 12, 24 or 48V

Output: 1 – 16V

Current: Up to 22A

As small as 7 x 8 x 0.85mm

Unmanned aircraft for communications

This class of UAV depends on solar power to meet its long flight time requirements. Solar power systems rely on the use of maximum power-point tracking (MPPT) circuitry to ensure that solar energy is harvested at the optimum voltage before conversion to a voltage suitable for charging a secondary battery, or delivery to the power systems intermediate bus network. As this class of UAVs develops, high-efficiency power-conversion topologies such as zero-voltage switching and zero-current switching (ZVS/ZCS) which are used in Vicor BCMs are important to enable the widening variety of fuel sources and applications with increasing power challenges.

Power delivery network

A combination of the BCM6123 providing the isolated conversion of the 350V to a 48V intermediate bus and the PI3741 ZVS Buck-Boost regulator with a very wide range input voltage operating capability provides a tightly regulated 28V output for various UAV loads.