Fire Ventilation Fan Pressure Control for Stable Escape Routes
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Solution Overview
Problem
Current fire ventilation systems, particularly those using PID controllers, face instability due to non-linear and dynamic characteristics of buildings, leading to oscillations and inability to maintain safe escape routes within the required three-second transition period, especially in newly constructed buildings with varying leakage and wind conditions.
Innovation Solution
A pressure controller with high computational efficiency and a floating-point arithmetic processor divides the control process into static and dynamic components, with a non-linear dynamics model created based on fan identification tests, allowing for real-time optimization of fan frequency control using an iterative method to achieve stable air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a PID controller is used to control fan speed based on pressure sensor feedback, then the system can automatically adjust fan power, but the system becomes unstable and oscillates due to non-linear and dynamic building characteristics
Solution Approach 1:
The control system transitions from static PID parameters to dynamic adaptive parameters. The controller continuously identifies building leakage characteristics and wind conditions in real-time, adjusting control parameters dynamically to match changing operating conditions. This allows the system to adapt to non-linear and dynamic building characteristics, eliminating oscillations while maintaining automatic control.
Solution Approach 2:
The system employs continuous feedback not only from pressure sensors but also from ongoing identification of building characteristics. The controller uses real-time pressure difference measurements combined with identified leakage parameters to continuously refine control actions. This multi-layered feedback mechanism enables the system to compensate for non-linearities and maintain stability under varying conditions.
2Reliability
If the fan flow rate is increased to ensure air speed in open door conditions, then escape route protection is improved, but the transition time between closed-door and open-door states exceeds the required three seconds
Solution Approach 1:
The controller performs preliminary identification of building leakage characteristics and pre-calculates optimal control strategies. When a door opening is detected, the system already has identified parameters ready, enabling immediate calculation of the required fan speed increase. This preliminary preparation allows the system to achieve the target air speed in the open-door state within the required three-second transition window.
Solution Approach 2:
The system dynamically adjusts fan speed based on real-time identification of building characteristics. During door opening transitions, the controller uses currently identified leakage parameters to calculate the precise fan speed adjustment needed, enabling rapid response that meets the three-second requirement while ensuring adequate air speed for escape route protection.
3Device complexity
If passive mechanical systems with constant flow rate fans are used, then device complexity is reduced, but the system cannot adapt to varying wind conditions and building leakage changes
Solution Approach 1:
The control system performs self-identification of building leakage characteristics and wind conditions without requiring external calibration or manual adjustment. The ongoing identification process allows the system to automatically adapt to changing conditions, maintaining optimal performance while keeping the physical device structure relatively simple. The added intelligence is software-based, preserving mechanical simplicity while enhancing adaptability.
4Stress or pressure
If wind blowing along the vent plane occurs, then dynamic pressure increases and static pressure decreases, but this causes complete vent opening and permanent blockage in passive systems
Solution Approach 1:
The active control system continuously monitors pressure difference and uses identified building characteristics to distinguish between pressure changes caused by wind and those caused by door openings or leakage variations. This feedback mechanism allows the controller to maintain appropriate fan speed adjustments, preventing erroneous vent opening or blockage that would occur in passive systems responding only to raw pressure signals.
Data Source
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AI summary
The object of the invention is a system for controlling a fan insufflating air into a protected space, especially in fire ventilation for the protection of escape routes, comprising a controller equipped with a processor with a high computational power and a memory, designed and configured to control the said fan by setting frequency U of the inverter controlling the motor of said fan and connected to this inverter, and in addition connected to a pressure sensor for measuring pressure difference P between the protected space and a reference pressure, characterised in that the said controller is configured and programmed to perform the following steps: a) registering, in the memory of the controller, parameters of the fan, determined in time; b) registering, in the memory of the controller, parameters of the protected space, variable in time; c) determining the value of parameter a(k) at current moment k as a function of a(k)=P(k)/U2(k); d) determining the value of control U(k+1) at a subsequent moment of time k+1, by solving the task of non-linear optimisation by means of an iterative method, the feasible point of the iterative method being assumed as Ustart(k+1)=Sqrt(P(k)/a(k)); e) setting the so determined value of control U(k+1) as a frequency of the inverter controlling the fan motor. The object of the invention is also a method for controlling a fan insufflating air into a protected space, especially in fire ventilation for the protection of escape routes.