Fan Flow Measurement Using Motor Internal Variables
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Solution Overview
Problem
Existing methods for determining the current conveying volume flow of a fan are inaccurate and complex, particularly when using vane anemometers due to influence from operating-state-dependent and swirl-affected flow patterns.
Innovation Solution
A method that combines motor-internal variables, such as electric current or motor speed, with motor-external variables, like measuring wheel speed or differential pressure, using an algorithm to accurately calculate the conveying volume flow, eliminating dependency on purely motor-external signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vane anemometer is used to measure volume flow, then volume flow can be determined, but measurement precision deteriorates due to operating-state-dependent and swirl-affected flow patterns
Solution Approach 1:
The patent uses motor-internal variables (current, speed, torque) as intermediary parameters to indirectly determine volume flow, avoiding direct measurement in the disturbed flow field. These motor variables serve as mediators that correlate with volume flow without being affected by swirl and operating state variations, thereby improving measurement precision while keeping the system simple.
Solution Approach 2:
The patent replaces the mechanical vane anemometer measurement system with an electrical measurement system based on motor variables. By substituting mechanical flow measurement with electrical parameter measurement (current, speed, torque), the system achieves higher precision without the drawbacks of mechanical measurement in disturbed flow conditions.
2Measurement precision
If multiple motor variables are combined for volume flow determination, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes the motor serve multiple functions: it not only drives the fan but also acts as a measurement sensor through its internal variables (current, speed, torque). This multi-functionality allows precise volume flow determination without adding separate measurement devices, thereby improving precision while avoiding increased device complexity.
Solution Approach 2:
The motor serves itself as a measurement device by utilizing its own operational variables (current, speed, torque) to determine volume flow. This self-service approach eliminates the need for external complex measurement systems, achieving high precision while maintaining simple device architecture.
3Ease of operation
If motor-internal variables are used for volume flow determination, then ease of operation improves, but measurement precision may deteriorate without additional sensors
Solution Approach 1:
The patent merges motor-internal variables (current, speed, torque) with algorithmic processing to achieve precise volume flow determination. By combining these easily accessible motor parameters through calibrated relationships and calculations, the system achieves both ease of operation (using existing motor data) and high measurement precision (through multi-parameter correlation).
Data Source
AI summary
The present disclosure relates to a method for quantitatively determining the current conveyed volumetric flow rate or another operating-point-dependent variable of a fan which comprises a motor-driven impeller, which method uses a motor-internal variable and a motor-external variable, from which the conveyed volumetric flow rate or another operating-point-dependent variable is directly or indirectly calculated or determined by means of an algorithm.