Dual-Controller 6-Phase Motor PWM Synchronization for Fault Tolerance
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Solution Overview
Problem
UAM vehicles are vulnerable to motor controller malfunctions during flight, which can lead to severe crashes due to the need for continuous power and control, lacking redundancy and fault-tolerance mechanisms.
Innovation Solution
A dual controller system is employed to synchronize the control of a 6-phase motor, using a first controller to manage abc phases and a second controller to manage xyz phases, with synchronized switching PWM signals generated through up-down counters and timers to ensure reliable operation even in case of controller failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single controller is used for motor control, then the device complexity is low, but the reliability is insufficient due to lack of redundancy
Solution Approach 1:
The motor control system is segmented into two independent controllers (first controller and second controller), each managing specific phases (abc phases and xyz phases respectively). This segmentation provides redundancy so that if one controller fails, the other can maintain basic motor operation, thereby improving reliability while keeping each controller's internal structure relatively simple.
Solution Approach 2:
The dual controller architecture acts as a preventive measure against controller failure. By having two controllers in place before any failure occurs, the system cushions against potential reliability issues. The controllers are designed to work together with synchronized PWM signals, ensuring that even if one fails, the system has already prepared a backup control path.
2Reliability
If dual controllers are used for redundant control, then the reliability is improved, but the synchronization between controllers becomes complex
Solution Approach 1:
The first controller and second controller are merged in functionality to control the same 6-phase motor with coordinated PWM signals. They share the same control objective and work in parallel, with their outputs combined at the motor phases. This merging approach simplifies the synchronization requirement compared to sequential or hierarchical control architectures.
Solution Approach 2:
The second controller essentially copies the control logic and PWM generation functionality of the first controller, but applied to different phase groups (xyz phases). This copying strategy ensures both controllers operate identically in terms of control algorithm, reducing synchronization complexity to mainly timing alignment of PWM signals rather than complex coordination of different control strategies.
3Reliability
If synchronized PWM signals are generated by dual controllers, then the operational safety is improved, but the control system complexity increases
Solution Approach 1:
The controllers are designed to pre-calculate and pre-synchronize their PWM signal generation parameters before actual motor operation begins. The switching patterns, duty cycles, and phase timing are predetermined and configured in advance, allowing the dual controllers to simply execute pre-synchronized control routines rather than continuously coordinating complex real-time decisions, thereby reducing operational complexity.
Data Source
AI summary
An apparatus for synchronously controlling a 6-phase motor includes: a first controller configured to calculate a length of a next switching pulse-width modulation (PWM) period, output at least one PWM signal indicating a length value of the next switching PWM period, and control abc phases of the 6-phase motor by using a control duty for the abc phases and the length value of the next switching PWM period. The apparatus also includes a second controller configured to obtain the length value of the next switching PWM period according to the at least one PWM signal, and control xyz phases of the 6-phase motor by using a control duty for the xyz phases and the length value of the next switching PWM period.