Hydraulic Actuator PWM Control Synchronization
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Solution Overview
Problem
PWM systems used in cam phaser oil control valves experience unpredictable and slow delays due to outdated actual and desired camshaft angle measurements, leading to inefficient control of the duty cycle.
Innovation Solution
Implementing a synchronization mechanism where the difference between actual and desired system parameters is calculated in real-time, allowing for immediate updates to the duty cycle, and aborting the current PWM signal period if a large error threshold is exceeded to restart with a new desired duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If actual and desired camshaft angle measurements are taken on independent time schedules, then the system can operate with separate measurement and control cycles, but the delays become unpredictable and too slow for fast-paced systems
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the time schedules so that actual and desired parameter measurements are taken at coordinated intervals. This ensures that when the duty cycle is calculated, both parameters are current and consistent, eliminating unpredictable delays while maintaining efficient separate measurement cycles
Solution Approach 2:
The patent implements feedback by continuously monitoring the relationship between actual and desired parameters on synchronized time schedules. This feedback mechanism ensures that outdated information is detected and corrected, maintaining fast and predictable control response in cam phaser systems
2Measurement precision
If the PWM signal period is immediately aborted and restarted when a large error threshold is exceeded, then the responsiveness and accuracy of actuator control is improved, but the control system complexity increases
Solution Approach 1:
The patent applies dynamics by making the PWM signal period adaptive rather than fixed. When a large error threshold is detected between actual and desired parameters, the system dynamically aborts and restarts the PWM period to correct the error. This dynamic adjustment improves control accuracy without requiring complex additional hardware, as it uses software-based adaptive timing control
Data Source
AI summary
A method, control system, and variable valve timing system are provided for controlling an actuator that can be switched into an on state and an off state with pulse width modulation. The systems and method include controls configured to determine an actual system parameter on a first time schedule and a desired system parameter on a second time schedule. On a third time schedule, a position error difference between the actual system parameter and the desired system parameter is determined. The third time schedule is configured to begin and to determine the position error difference each time that the actual system parameter is determined and each time that the desired system parameter is determined. A desired duty cycle is determined, and a duty cycle command is sent to a pulse width modulation output unit.