On-Off Valve PWM Control for Stable Parameter Regulation
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Solution Overview
Problem
Existing systems face challenges in accurately controlling system parameters using on-off valves due to undesirable effects from overcorrection and instability caused by full saturation of duty cycles in pulse width modulation, particularly in environments with varying inlet pressures.
Innovation Solution
Implementing a control system that sets an initial upper limit on the duty cycle of pulse width modulation signals and gradually increases it over time, combined with adaptive gain adjustments, to prevent overcorrection and stabilize valve position, thereby achieving smooth transient and steady-state responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If full saturation duty cycle is used in pulse width modulation to control on-off valve, then rapid response is achieved, but overcorrection and instability occur
Solution Approach 1:
The patent applies dynamics by making the duty cycle upper limit adjustable and time-dependent rather than fixed. The controller dynamically modifies the upper limit based on system response, transitioning from lower initial limits to higher limits as the system stabilizes, thereby adapting the control aggressiveness to the current system state and avoiding overcorrection
Solution Approach 2:
The patent implements preliminary action by setting an initial upper limit on the duty cycle before full control begins. This preliminary constraint prevents excessive initial corrections that would cause instability, allowing the system to settle before permitting higher duty cycles that enable faster response
2Loss of time
If duty cycle upper limit is increased to improve response time, then faster system response is achieved, but phase differences and oscillations increase
Solution Approach 1:
The controller dynamically adjusts the duty cycle upper limit based on the system's transient response characteristics. By monitoring whether the system parameter reaches the target value within a specified time frame, the controller adaptively increases or maintains the duty cycle limit, optimizing both response time and control accuracy without causing oscillations
3Productivity
If aggressive control action is taken to reduce transient time, then faster regulation is achieved, but system instability and overcorrection occur
Solution Approach 1:
The patent applies preliminary action by establishing an initial constrained duty cycle upper limit before full control operation begins. This preliminary constraint prevents aggressive initial control actions that would cause overcorrection, allowing the system to stabilize before enabling more aggressive control for faster regulation
Solution Approach 2:
The controller uses feedback by monitoring the system parameter response to determine whether to increase the duty cycle upper limit. Based on whether the target value is reached within the specified time, the controller adaptively adjusts the duty cycle limit, creating a feedback loop that balances regulation speed with system stability
Data Source
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AI summary
Methods and systems for operating an on-off valve (204) coupled to a system (200) for regulating a system parameter are described herein. The method comprises setting an upper limit on a duty cycle of a pulse width modulation (PWM) signal for controlling the valve (204), generating the PWM signal with the duty cycle less than or equal to the upper limit and applying the PWM signal to the valve (204), monitoring the system parameter as the PWM signal is applied, and increasing the upper limit on the duty cycle over time until the system parameter reaches a target.