eVTOL Rotor Lock Using Inverter Circulatory Current
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Solution Overview
Problem
Current electric motor systems in eVTOL aircraft lack an efficient method to lock rotors at desired positions without relying on mechanical locks or complex dynamic controls, which can add weight and energy costs.
Innovation Solution
Implementing an electronic lock within the power inverter by selectively closing switches to create a circulatory current flow path, generating an opposing force to hold the rotor at a predefined position, eliminating the need for mechanical locks and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical locks or complex dynamic controls are used to lock rotors at desired positions, then rotor positioning reliability is improved, but system weight and device complexity increase
Solution Approach 1:
The patent replaces mechanical locking systems with an electronic locking mechanism implemented through the power inverter's switch arrangement. By selectively closing specific switches (e.g., S1 and S2 in a two-switch inverter configuration), the system creates a circulatory current path that generates electromagnetic torque to hold the rotor at desired positions, eliminating the need for mechanical locks and reducing overall system complexity
Solution Approach 2:
The power inverter is designed to perform multiple functions: it not only drives the motor during normal operation but also provides rotor positioning control when switches are selectively closed to create the circulatory current path. This multi-functionality eliminates the need for separate positioning mechanisms, reducing device complexity while maintaining positioning reliability
2Reliability
If mechanical locks are added to lock rotors at desired positions, then rotor positioning is improved, but system weight increases
Solution Approach 1:
The patent eliminates mechanical locking components by implementing positioning control through the power inverter's electronic switch arrangement. The circulatory current path created by closing specific switches generates electromagnetic forces that hold the rotor at desired positions without requiring any additional mechanical parts, thereby avoiding weight increase
3Measurement precision
If complex dynamic controls are used to maintain rotor position, then positioning accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent uses periodic switching of the inverter's semiconductor switches to maintain rotor position. By selectively closing switches at appropriate intervals to sustain the circulatory current path, the system achieves precise positioning control while consuming minimal energy compared to continuous dynamic control methods. The periodic switching allows the system to maintain position with lower average power consumption
Solution Approach 2:
The system uses the motor's own back-EMF and existing electrical components to provide positioning control. The circulatory current path utilizes the motor's inherent electrical characteristics, eliminating the need for additional energy-consuming positioning systems while maintaining accurate rotor positioning
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
The electronic lock allows for efficient rotor positioning without additional mechanical components or energy requirements, enhancing flight control and reducing drag, while maintaining system simplicity and weight reduction.
Implementation Method 1
closing a subset of switches from the arrangement of switches within the power inverter to provide a circulatory current flow path within the power inverter such that in response to external movement of the rotor, the current flowing in the circulatory current flow path within the power inverter will generate an opposing force to oppose the movement of the rotor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
There is disclosed an electronic rotor "lock" that can be implemented within an electric motor system by selecting closing a subset of switches within an inverter (200) of the motor drive system to create a circulatory current path that can generate a force that acts to oppose any external movement of the rotor (12).