Motor Controller Constant Airflow Mode for Low-Airflow Blower Accuracy
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Solution Overview
Problem
Existing motor controllers for electric motors driving blowers face significant errors in estimating airflow output at low airflow levels due to factors like parasitic current, noise in current sensing, magnetic flux changes, and variability in calibration procedures, leading to inefficiencies and inaccuracies, especially when operating outside the calibrated speed-torque operating profile.
Innovation Solution
A motor controller with a processor and memory that stores speed-to-airflow ratios and operates the motor in either constant speed or torque modes to accurately generate desired airflow outputs by using a single calibration point, reducing the impact of torque errors and linearly extrapolating speed-to-airflow ratios to achieve objective airflow levels with minimal computational error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple calibration points are used to improve airflow estimation accuracy, then measurement precision improves, but device complexity and calibration time increase
Solution Approach 1:
The patent extracts and eliminates torque-related error sources from the calibration process by operating exclusively in constant airflow mode, where torque variations do not affect airflow output. This removes the need for torque calibration and reduces calibration complexity while maintaining accuracy.
Solution Approach 2:
The patent changes the operating parameter from torque-control mode to constant airflow mode, fundamentally altering how the blower is controlled. This parameter change eliminates torque errors from the equation and simplifies the calibration to require only airflow measurements rather than both torque and airflow data.
2Use of energy by moving object
If torque-control mode is used to operate the blower, then power efficiency improves, but airflow estimation accuracy deteriorates at low airflow levels
Solution Approach 1:
Instead of controlling torque and measuring airflow (the conventional approach), the patent inverts the approach by directly controlling airflow and using torque only as a monitoring parameter. This inversion eliminates the fundamental problem of torque errors affecting airflow measurements.
Solution Approach 2:
The patent implements feedback control in constant airflow mode, where the system continuously monitors actual airflow output and adjusts motor operation to maintain the desired airflow level, thereby improving both accuracy and efficiency through closed-loop control.
3Manufacturing precision
If calibration is performed at high airflow levels, then manufacturing precision is easier to achieve, but reliability at low airflow levels deteriorates
Solution Approach 1:
The patent performs preliminary calibration at convenient airflow levels during manufacturing, storing the calibrated airflow characteristics in memory. This preliminary action allows the system to then reliably operate at any airflow level including low levels, without requiring recalibration.
Solution Approach 2:
The patent creates a universal calibration approach where a single calibration performed at any airflow level can be used to control the blower across its entire operating range, making the calibration process universally applicable rather than requiring separate calibrations for different operating conditions.
Data Source
AI summary
A motor controller for an electric motor is provided. The electric motor is configured to drive a blower to generate an airflow. The motor controller includes a memory and a processor coupled thereto. The memory is configured to store a speed-to-airflow ratio associated with an airflow restriction on the blower. The processor is configured to receive a command for a calibrating airflow and operate the electric motor in a constant airflow mode to generate the calibrating airflow at a calibrating speed. The processor is further configured to write the calibrating speed and the calibrating airflow to the memory as the speed-to-airflow ratio.