Hybrid Aircraft Propulsion Energy Storage for HVDC Bus Stability
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Solution Overview
Problem
Existing hybrid propulsion installations for multi-rotor rotary wing aircraft are burdened by significant mass and complexity due to secondary storage elements, which have high self-discharge rates, require periodic recharging, and are prone to degradation and thermal runaway, posing electrical risks and increasing the system's probability of failure.
Innovation Solution
Incorporating a hybrid energy storage system with a non-rechargeable primary storage element connected in series and a rechargeable secondary storage element connected in parallel, eliminating the need for a Battery Management System (BMS) and utilizing primary storage elements that are single-shot, self-discharge-free, and resistant to harsh environments, thereby simplifying the system and reducing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary storage elements (rechargeable batteries) are used for energy storage, then the system can provide redundant power supply and stabilize voltage, but the mass of the installation increases significantly and the system complexity increases due to BMS requirements
Solution Approach 1:
The patent divides the energy storage system into two independent segments: primary storage elements (non-rechargeable batteries) and secondary storage elements (rechargeable batteries or capacitors). Each segment performs a specific function - primary elements provide bulk energy storage while secondary elements provide voltage stabilization and peak power delivery. This segmentation allows the system to achieve reliability without requiring a single large, heavy rechargeable battery system with complex BMS.
Solution Approach 2:
The primary storage elements (non-rechargeable batteries) serve multiple functions simultaneously: they provide redundant power supply for emergency operations, stabilize the HVDC bus voltage, and eliminate the need for BMS. This multi-functionality reduces overall system mass and complexity while maintaining reliability.
2Stability of the object's composition
If secondary storage elements are used, then voltage stabilization is achieved, but the probability of failure increases due to degradation and thermal runaway risks
Solution Approach 1:
The patent introduces an intermediary element - the primary storage element (non-rechargeable battery) connected in series with the HVDC bus - that acts as a voltage reference and stabilizer. This intermediary provides inherent voltage stability without the degradation and thermal runaway risks associated with rechargeable batteries, as it does not require charging cycles and has simpler chemistry.
Solution Approach 2:
The system uses non-rechargeable (primary) storage elements that are replaced rather than recharged. These elements have no self-discharge, do not degrade over time like rechargeable batteries, and eliminate thermal runaway risks. Their disposable nature simplifies the system by removing BMS requirements while maintaining voltage stability.
3Reliability
If secondary storage elements are used, then emergency power supply is provided, but the device complexity increases due to BMS and charging infrastructure
Solution Approach 1:
The patent extracts the BMS and charging infrastructure from the system by using non-rechargeable primary storage elements. The primary elements require no management system, no charging equipment, and no monitoring electronics. This extraction dramatically reduces device complexity while maintaining emergency power supply capability through the hybrid architecture.
Solution Approach 2:
The primary storage elements are self-service in nature - they require no external management, charging, or monitoring. They simply provide voltage stabilization and emergency power until depleted, at which point they are replaced. This self-service characteristic eliminates the need for complex BMS and charging infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures reliable emergency landing capabilities, stabilizes the HVDC bus voltage, minimizes electrical constraints, and reduces the overall mass and volume of the propulsion system while eliminating the risk of thermal runaway and the need for complex electronic management systems.
Implementation Method 1
a rectifier connected to the electric generator and configured to convert an alternating current delivered by the electric generator into a direct current
Implementation Method 2
means for converting direct current into alternating current, an electrical network connecting the rectifier to the conversion means
Implementation Method 3
an electric generator coupled to the internal combustion engine so that in operation the internal combustion engine drives the electric generator
Implementation Method 4
electric motors connected to the conversion means so that in operation the conversion means supply the electric motors with alternating current
Data Source
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AI summary
The invention relates to a hybrid propulsion unit (100) for an aircraft with multi-rotor rotary wings: an electrical generator (114) driven by an internal combustion engine (112), a rectifier (116) configured to convert an AC current sent by the electrical generator into DC current, means for converting (118a, 118b, 118c, 118d) DC current into AC current, an electrical network (120) connecting the rectifier to the conversion means and including a high-voltage DC current bus, electric motors (122a, 122b, 122c, 122d) powered by the propeller conversion means (124a, 124b, 124c, 124d) coupled to the electric motors, the unit being characterized in that it comprises means for storing electrical energy (126) connected to the electrical network, the storage means comprising at least one primary storage element (138) and at least one secondary storage element (140).