Method for estimating external static pressure in air duct of air conditioning system and method for controlling air conditioning system
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Solution Overview
Problem
Existing HVAC systems face impractical and costly static pressure measurement challenges due to bulky and expensive devices, making it inefficient to monitor external static pressure in air ducts, which is crucial for optimizing system performance and identifying filter clogging.
Innovation Solution
A method using a permanent magnetic motor with a stator assembly, rotor assembly, and micro control unit to calculate external static pressure by applying a constant current, ensuring a constant volumetric airflow rate, and transmitting data to a system controller for real-time estimation and control, eliminating the need for additional measurement devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static pressure measurement devices are installed in each air duct, then external static pressure can be measured accurately, but the system becomes costly and complex with bulky devices and complex wiring
Solution Approach 1:
The PM motor uses its own operational parameters (current, voltage, speed) to calculate external static pressure, eliminating the need for separate measurement devices. The motor essentially measures pressure for itself by monitoring its own performance characteristics during fan operation.
Solution Approach 2:
The patent replaces mechanical/static pressure measurement devices with an electrical/control-based calculation system. By using the relationship between motor electrical parameters and mechanical output, the system computes pressure without physical pressure sensors or measurement equipment in the air ducts.
2Reliability
If filters are replaced every three months, then filter clogging is prevented, but unnecessary replacements occur increasing expenses
Solution Approach 1:
The system continuously monitors external static pressure and provides feedback about filter clogging conditions. This real-time information allows the system to determine when filter replacement is actually needed based on measured pressure changes rather than following a fixed replacement schedule.
Solution Approach 2:
The system detects filter clogging early by monitoring gradual changes in external static pressure before the filter becomes fully blocked. This preliminary detection allows for timely filter replacement only when necessary, preventing both complete clogging and unnecessary early replacements.
3Productivity
If constant current is applied to the PM motor, then constant volumetric airflow rate is achieved, but the system requires precise control mechanisms
Solution Approach 1:
The PM motor controller automatically adjusts current to maintain constant airflow by monitoring the motor's own operational state and external static pressure conditions. The control system uses the motor's back-EMF and current measurements to self-regulate and maintain desired airflow without external intervention.
Solution Approach 2:
The patent replaces mechanical airflow control mechanisms (such as dampers or variable pitch blades) with electrical control of the PM motor. By controlling the electrical input to the motor based on pressure feedback, the system achieves airflow control through electrical means rather than mechanical adjustments.
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 approach allows for real-time estimation and control of external static pressure without additional costs, reducing unnecessary filter replacements and identifying potential faults within the HVAC system, enhancing operational performance and reducing expenses.
Implementation Method 1
a permanent magnetic (PM) motor and a fan in an air duct, wherein the PM motor comprises a stator assembly, a permanent-magnet rotor assembly, and a motor controller; the fan is powered by the PM motor
Implementation Method 2
calculating an external static pressure (ESP) on the air duct using two variables: the constant volumetric airflow rate (CFM) of the air duct and an input power (POWER) of the PM motor
Data Source
AI summary
A method for estimating an external static pressure (ESP) in an air duct, includes: disposing a permanent magnetic (PM) motor and a fan in an air duct, where the PM motor includes a stator assembly, a permanent-magnet rotor assembly, and a motor controller; the motor controller includes a micro control unit (MCU); and the fan is powered by the PM motor; applying a constant current to the PM motor so that the air duct outputs a constant volumetric airflow rate in a unit of cubic feet per minute (CFM); and calculating an external static pressure (ESP) on the air duct using two variables: the constant volumetric airflow rate (CFM) of the air duct and an input power (POWER) of the PM motor.