PWM Synchronization via Master Controller Feedback
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Solution Overview
Problem
In motor control systems with redundant motors or windings, unsynchronized pulse-width modulated signals can lead to torque ripple, vibration, noise, and other issues due to manufacturing tolerances causing frequency differences in internal oscillators.
Innovation Solution
A method is implemented where a master controller generates a clock signal and synchronization signal, adjusting the frequency of local clock signals in slave controllers to synchronize PWM signals across multiple motors, ensuring non-overlapping drive currents and independent plausibility checks for system failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple internal oscillators are used in redundant motor systems, then each motor can operate independently, but frequency differences due to manufacturing tolerances cause torque ripple and vibration
Solution Approach 1:
The system uses a master controller to monitor synchronization signals from slave controllers and implements a feedback mechanism that sends frequency adjustment commands to correct timing deviations. This closed-loop feedback ensures that PWM signals from multiple motors remain synchronized, eliminating torque ripple and vibration while maintaining redundant operation.
Solution Approach 2:
The master controller dynamically adjusts the frequency parameter of slave clock signals based on detected timing differences. By changing the frequency parameter in real-time, the system synchronizes PWM signals from multiple motors without requiring identical manufacturing tolerances, thus eliminating harmful torque ripple and vibration effects.
2Object-generated harmful factors
If PWM signals are synchronized across multiple motors, then torque ripple and vibration are reduced, but system complexity increases due to master-slave controller architecture
Solution Approach 1:
The system merges the timing control function into a single master controller that generates reference clock signals and synchronization commands. This consolidation eliminates the need for each motor controller to independently generate and coordinate timing signals, reducing overall system complexity while achieving PWM synchronization and torque ripple reduction.
Solution Approach 2:
The master controller acts as an intermediary between slave controllers and the central control system. It receives synchronization signals from slaves, processes timing information, and sends frequency adjustment commands back to synchronize PWM signals. This intermediary role simplifies the architecture by centralizing timing coordination functions.
3Manufacturing precision
If frequency adjustment commands are continuously sent to synchronize clock signals, then PWM signals remain synchronized, but communication bandwidth and processing load increase
Solution Approach 1:
The master controller sends frequency adjustment commands periodically based on detected timing deviations rather than continuously. This periodic action maintains PWM signal synchronization while significantly reducing communication bandwidth requirements and processing load compared to continuous adjustment, thereby reducing energy loss.
Solution Approach 2:
Slave controllers autonomously monitor their own clock signal timing and generate synchronization requests when deviations are detected. This self-service approach reduces the communication overhead on the master controller, as slaves independently manage their own synchronization needs and only communicate when adjustment is required.
Data Source
AI summary
In accordance with an embodiment, a method includes generating a clock signal; generating a switching signal based on the clock signal; generating a synchronization signal having an edge transition corresponding to a predetermined phase of the switching signal; transmitting the synchronization signal to a master controller; receiving a frequency adjustment command from the master controller based on the transmitted synchronization signal; and adjusting a frequency of the clock signal based on the frequency adjustment command.