Fan Control System for Ventilation Noise and Thermal Drift
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Solution Overview
Problem
Multi-zone ventilation or air conditioning systems face challenges in precisely adjusting fan flow rates, leading to excessive noise and thermal drift due to the unsuitability of three-speed asynchronous alternating current motors, which results in discomfort and inefficiency, especially when serving a subset of zones.
Innovation Solution
A ventilation or air conditioning system that includes a fan control system using a pressure sensor to regulate the electric motor's rotation speed and torque based on air pressure within the plenum, maintaining a predetermined pressure threshold, and a semiconductor switch to supply the motor with a time-varying voltage and current, ensuring a root mean square value and symmetry degree within specified tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-speed asynchronous alternating current motor is used to drive the fan, then the device complexity is reduced, but the manufacturing precision of air flow rate control deteriorates
Solution Approach 1:
The patent replaces the mechanical three-speed motor control system with an electronic control system using a microprocessor and pulse width modulation (PWM) circuitry. This substitution enables precise control of the fan motor speed by varying the duty cycle of the PWM signal, thereby achieving accurate air flow rate control while maintaining simple device architecture.
Solution Approach 2:
The patent changes the control parameter from discrete three-speed settings to continuous duty cycle percentage (0-100%). This allows the fan motor speed to be adjusted precisely across a wide range, enabling accurate matching of air flow rate to the actual thermal zones requiring conditioning, thus resolving the precision control issue while keeping the system simple.
2Productivity
If the fan operates at minimum speed to serve one zone, then the air flow rate to the single zone is reduced, but excessive noise and thermal drift occur
Solution Approach 1:
The patent applies local quality by detecting which specific zones require air conditioning through thermostat signals and directing air flow selectively to those zones via controllable valves. The fan operates at optimized speed for the active zones only, not at minimum speed for all zones, thereby maintaining adequate air flow to active zones while avoiding excessive noise and thermal drift that would occur at minimum speed operation.
Solution Approach 2:
The patent implements dynamic adjustment of fan motor speed based on the number and location of active thermal zones. The microprocessor continuously monitors thermostat signals and adjusts the PWM duty cycle in real-time, enabling the fan speed to dynamically match the actual air conditioning demand, thus avoiding the harmful effects of operating at fixed minimum speed.
3Adaptability or versatility
If shutters are adjusted zone by zone for multi-zone control, then the adaptability to different thermal zones is improved, but the difficulty of detecting and measuring flow rate increases
Solution Approach 1:
The patent implements feedback by using thermostats in each zone to detect temperature conditions and send signals to the microprocessor. The microprocessor processes these signals and automatically adjusts the fan speed and zone valve positions accordingly. This closed-loop feedback system eliminates the need for manual flow rate measurement and adjustment, making multi-zone control adaptable while simplifying the detection and measurement process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces noise and thermal drift by ensuring precise air flow rates to each zone, independent of the opening or closing of other nozzles, maintaining comfort and efficiency even when serving a subset of zones.
Implementation Method 1
a fan control system using a pressure sensor to regulate the electric motor's rotation speed and torque based on air pressure within the plenum
Implementation Method 2
a semiconductor switch to supply the motor with a time-varying voltage and current, ensuring a root mean square value and symmetry degree within specified tolerances
Data Source
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AI summary
The ventilation or air conditioning system (1) according to the invention comprises an air generator (3) in turn comprising A) a plenum (5) which forms an internal compartment (7) a outlet port (9) in fluid communication with the internal compartment (7); B) a fan (11) arranged for introduce air in the internal compartment (7) so as to generate a flow of air leaving the at least one outlet port (9). The fan (11) comprises an electric motor (13) and an impeller (15). The ventilation or air conditioning system (1) comprises a fan control system arranged for control the electric motor (13) on the basis on the air pressure present in the internal compartment (7) of the plenum (5). It enables to reduce noise and the thermal drift in a system provided with several nozzles, even when many of them, or all of them except for one, are closed, and also when the generator (3) is of a large size.