Heating Device Startup Detection Through Blower PWM Signals
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Solution Overview
Problem
Existing methods for detecting irregular ignition processes in heating devices during commissioning are unreliable, complex, and prone to delays due to interference with fan speed control systems, often leading to potential damage and breakdowns without immediate detection.
Innovation Solution
A method involving the monitoring and analysis of pulse-width modulated (PWM) signals from the speed control of the blower to detect irregular ignitions by evaluating changes in the control signal and its derivatives, allowing for automatic and reliable detection of hard ignitions and preventing subsequent attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fan speed control systems are used to detect irregular ignition by comparing current speed with target speed, then detection capability is provided, but the detection is delayed and complicated due to interference with speed control
Solution Approach 1:
The patent extracts the detection function from the speed control system by monitoring the PWM control signal separately. Instead of relying on speed feedback that is influenced by control interventions, the system directly observes the control signal that drives the fan motor, isolating the detection process from control interference and enabling immediate detection of irregularities.
Solution Approach 2:
The PWM control signal serves as an intermediary that carries information about both the control system's intentions and the actual system response. By monitoring this intermediate signal rather than the final speed output, the system can detect irregularities before they manifest as speed changes, avoiding the delays inherent in speed-based detection.
2Device complexity
If user observation and manual reporting of irregular ignition is used, then no additional device complexity is required, but detection reliability is low and damage risk increases
Solution Approach 1:
The system performs self-diagnosis by automatically monitoring its own control signals during operation. The control device evaluates the PWM signal characteristics to detect irregular ignitions, eliminating the need for external observation and manual reporting while maintaining simplicity through software-based detection rather than additional hardware.
3Measurement precision
If multiple parameters are monitored during burner start-up, then detection accuracy is improved, but device complexity and structural changes increase
Solution Approach 1:
The existing PWM control signal serves multiple functions: it controls the fan motor speed and simultaneously provides detection information for irregular ignition. By evaluating the characteristics of this single control signal (such as duty cycle variations, frequency changes, or distortion patterns), the system achieves accurate detection without requiring additional sensors or monitoring parameters.
Data Source
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AI summary
A method is proposed for detecting an irregular ignition process of a heating device (1), comprising a blower (2) and a speed control (6) for adjusting the speed (11) of the blower (2), designed to convey a mass flow of a mixture of fuel and combustion air to a burner (3) of the heating device (1), wherein during commissioning a pulse width modulated signal is detected as a control signal (10) of the speed control (6) and an irregular ignition process is detected by evaluating the control signal (10).