HVDC Bus Voltage Control for Hybrid Electric Aircraft Power Flow
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Solution Overview
Problem
There is a lack of effective solutions for active power flow control and battery power management in hybrid electric aircraft equipped with batteries that store hundreds of kilowatt-hours of energy, particularly in managing the high-voltage direct-current (HVDC) bus voltage.
Innovation Solution
A hybrid electrical power supply system incorporating a solid-state HVDC bus voltage controller with an active voltage controller and an active rectifier unit using pulse-width modulated (PWM) control to manage the HVDC bus voltage, enabling precise control of battery charge and discharge rates and power flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If batteries are used to supply electrical power for propulsion in hybrid electric aircraft, then a large amount of energy can be stored, but the battery voltage cannot be actively controlled and power flow management becomes difficult
Solution Approach 1:
An active rectifier unit is introduced as an intermediary device between the battery and the HVDC bus. This rectifier unit actively controls the battery voltage and power flow, mediating between the battery's inherent voltage characteristics and the system's voltage requirements, thereby enabling voltage control without modifying the battery itself
Solution Approach 2:
The system dynamically changes the battery voltage parameter through active control of the rectifier unit. By adjusting the rectifier's switching characteristics and control parameters, the battery voltage can be actively regulated to match system requirements, transforming the battery from a passive voltage source to an actively managed power source
2Power
If the battery is designed to provide large power for propulsion, then the energy storage capacity increases, but the battery becomes large and requires paralleling with other power sources
Solution Approach 1:
The active rectifier unit serves multiple functions simultaneously: it controls battery voltage, manages power flow direction (charge/discharge), protects the battery from over-current, and interfaces with the HVDC bus. This multi-functionality reduces the need for separate control systems and simplifies the overall system architecture despite the high power requirements
3Extent of automation
If active power flow control is implemented at the HVDC connection, then battery power management is improved, but the system complexity increases
Solution Approach 1:
The control functions for the active rectifier unit are merged with the existing power management system. The rectifier's control circuit integrates voltage regulation, current limiting, and power flow management into a unified control architecture, reducing the need for separate control systems and minimizing overall system complexity
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 solution allows for accurate power management and extended battery life, optimizing energy usage based on flight phases, battery state of charge, and fuel reserves, while reducing weight and operational costs.
Implementation Method 1
The HVDC bus voltage controller includes an active voltage controller and an active rectifier unit configured to control the HVDC bus voltage using a pulse-width modulated (PWM) control technique
Data Source
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AI summary
A solid-state high-voltage direct-current (HVDC) bus voltage controller to provide active power flow control in a hybrid electric aircraft power supply system. The HVDC bus voltage controller includes an active voltage controller and an active rectifier unit configured to control the HVDC bus voltage using the PWM control technique. In one implementation, the active rectifier unit includes high-power and high-frequency semiconductor switches with fast turn-off capabilities. The active voltage controller sends an HVDC bus reference voltage to the active rectifier unit. The low-level controller inside the active rectifier unit is configured to control the HVDC bus voltage to match the HVDC bus reference voltage.