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250W Power Management Unit - Version 2
250W Power Management Unit - Version 2
The 250W Power Management Unit provides on-board electrical power generation, battery management and power distribution for small to medium-sized UAVs. Version 2 increases the total power available, and supports higher input voltages.
The 250W PMU converts 3-phase AC from a BLDC motor into a set of regulated DC outputs suitable for powering a vehicle's avionics, servo and payload demands. Output rails are maintained from battery power whenever electrical power generation is not occurring.
The PMU has dual battery inputs with automatic and glitch-free switchover between the two. Each battery input has its own battery charger. An umbilical input ensures that batteries are not depleted during pre-flight checks prior to take-off.
Output rails and battery chargers are user-configurable for voltage, allowing the PMU to be adapted to a vehicle's voltage plan, rather than the other way around.
The version 2 PMU is externally identical to the original 250W PMU. Changes are documented in the product update bulletin.
Features:- NEW in version 2: High-voltage 3-phase inputs now support voltages up to 130 Vpp.
- NEW in version 2: Master shutdown input allows batteries to stay connected without discharging.
- NEW in version 2: Increased power available from the main 28V Buck-boost converter - up to 500W peak.
- NEW in version 2: Improved configuration software shows real-time power flows within the PMU graphically.
- Multiple independent, individually user-programmable power outputs:
- Avionics: 12 - 21 VDC, 7.5 Amps (120W max.)
- Payload: 12 - 21 VDC, 7.5 Amps (120W max.)
- Servo: 5 - 12 VDC, 10 Amps (120W max.)
- Outputs are battery-backed and switchable (on/off) via hardware signal or remotely via command.
- Dual (redundant) battery support. The PMU includes two independent and identical battery chargers. Supported battery types include:
- LiPo: 5S, 6S
- LiS: 8S, 9S, 10S
- LiFe: 6S, 7S
- Industry-standard 28 VDC output (available during power generation and when the PMU is connected to umbilical power).
- RS232 and CAN control and monitoring interfaces provides extensive monitoring and reporting of voltages, currents, battery charge status, temperatures.
- Optional engine starter may be activated locally via a momentary push-button switch, or remotely via command to facilitate in-flight engine restarting (Currawong Engineering variant).
- Weight: 315g (11.1oz).
- Dimensions: 124.4 x 85.0 x 32.5mm
The 250W PMU integrates seamlessly with Currawong Engineering's Corvid-29 and Corvid-50 engines when purchased as part of an EFI powertrain solution. Contact Currawong Engineering to discuss your requirements, obtain further technical information, or request a quote.
The 250W PMU is also distributed internationally from the US by HFE International and from Europe by VISIONAIRtronics.
If you are located closer to Australia, you can choose to purchase from Millswood Engineering.
Quality:The 250W PMU is manufactured in an ISO9001:2015 compliant facility using lead-free components and processes. Completed PMUs are tested and given a unique serial number to maintain traceability. All PMUs are shipped with an acceptance sheet (certificate of compliance).
Configuration software
Real-time monitoring & control
The configuration utility has been updated to show reported telemetry values in a more intuitive way.
The "Monitor" tab is now a block diagram of the PMU over which the telemetry values are overlaid.
Voltages, currents, power flows, temperatures, etc are shown where they occur, and are updated in real-time.
Various blocks may be turned on and off using the checkboxes, again overlaid over the block they control.
The new configuration software may be used with version 1 PMUs.
Output power
Power available from the new 28V Buck-Boost converter
The heart of the 250W PMU is the 28V Buck-Boost switching converter. This DC-DC converter takes generated electrical power and converts it down to 28V for the downstream DC-DC converters. This converter has been redesigned to work across a larger range of input voltages and produce more output power.
It now supports input voltages in excess of 130V, and can easily deliver 500W of peak power.
The maximum continuous power available is mainly determined by the ambient temperature, as shown in the graph on the right. For example, at an ambient temperature of 30°C, the new converter can produce 250W continuously from 26.5V up to 85V. When the converter's temperature exceeds its internal thermal limit, it shuts down to protect itself and downstream converters operate from battery power. The converter restarts automatically when its temperature falls to within normal limits.
A speed-proportional power limit has been implemented to prevent electro-mechanical instability. This can happen when loads are suddenly applied to an engine running at low RPM. Gradually reducing the amount of power that the PMU can draw from the engine at low RPM solves this problem in the majority of cases. If additional power is demanded from the PMU at low RPM, the shortfall is supplied from battery power.
Product resources
- Documentation:
- Product brief: a short summary of the key features and specifications.
- Product manual: detailed description of the PMU hardware - how it works, how to connect it up, electrical and mechanical specifications, how to choose a suitable BLDC motor, etc.
- RS232 protocol: describes what values the PMU can measure and transmit, what commands it can receive, and how this data is formatted.
- CAN protocol: describes what values the PMU can measure and transmit, what commands it can receive, and how this data is formatted.
- Software:
- Configuration utility: a Windows app for configuring the PMU and checking that it is all working correctly.
More resources are available here.