Ventilation Fan Current Feedback for Constant Airflow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ventilation systems face challenges in maintaining a constant air flow volume despite variations in static pressure, as existing fan systems can only adjust air flow in limited steps, leading to inconsistent performance.
Innovation Solution
A fan system with a motor, current sensor, speed control unit, and controller that regulates motor speed and power supply using PWM signals to maintain a desired air flow rate by determining and adjusting motor speed and current based on actual operating conditions, utilizing a lookup table for fan performance values and system operating points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual speed selection with limited steps is used, then device complexity is reduced, but air flow volume stability deteriorates when static pressure varies
Solution Approach 1:
The patent implements dynamic speed adjustment by continuously monitoring actual motor current and comparing it with expected current values from lookup tables. When static pressure changes cause current deviations, the system automatically adjusts motor speed in real-time to maintain constant air flow volume, transforming the static manual speed selection into a dynamic closed-loop control system.
Solution Approach 2:
The system employs feedback control by measuring actual motor current through a current sensor and comparing it with expected current values stored in lookup tables. When the difference exceeds a threshold, the controller adjusts the motor speed accordingly, creating a closed-loop feedback mechanism that maintains air flow stability without requiring complex manual intervention.
2Ease of operation
If multi-step manual speed adjustment is implemented, then ease of operation is improved, but adaptability to varying static pressure deteriorates
Solution Approach 1:
The system performs self-adjustment by automatically detecting static pressure changes through motor current monitoring and autonomously adjusting motor speed to maintain constant air flow. The controller uses lookup tables storing performance characteristics to determine appropriate speed adjustments, enabling the system to adapt to varying operating conditions without operator intervention.
Solution Approach 2:
The patent pre-stores fan performance data and corresponding motor current values in lookup tables during system setup or manufacturing. When operation begins, the controller can quickly reference these pre-computed values to determine appropriate speed adjustments, eliminating the need for real-time complex calculations and enabling rapid adaptation to pressure changes.
3Device complexity
If constant speed operation is used, then device complexity is reduced, but air flow quantity control precision deteriorates when system conditions change
Solution Approach 1:
The system maintains simple hardware architecture while achieving precise air flow control by dynamically changing motor operating parameters (speed and current) based on actual system conditions. The controller monitors motor current and adjusts speed setpoints according to lookup table data, enabling precise air flow quantity control without complex mechanical speed control mechanisms.
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
The system effectively maintains a constant air flow volume by dynamically adjusting motor speed and power supply, ensuring consistent air flow regardless of static pressure changes, thereby improving system stability and performance.
Implementation Method 1
the inverter is controlled by PWM signals generated by the speed control unit
Data Source
AI summary
A fan for a ventilation system has a motor, a motor speed control unit and a controller arranged to control the motor to maintain the quantity of air flowing through the system constant. The controller compares the actual motor current with an expected motor current for the fan operating at the desired air quantity and motor speed to determine an actual system operating condition. When the difference between the actual motor current and the expected motor current is greater than a preset range, the motor speed is adjusted to a new motor speed determined based on the actual system operating condition. The system operating conditions may change due to changes in the static pressure of the system such as changes to the ventilation ducting or external wind pressure.