Motor Controller Speed-to-Airflow Calibration for Low-Airflow Accuracy
Find Innovative SolutionsGenerate Solutions
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, and magnetic flux changes, leading to inefficiencies and accuracy issues, especially when operating outside the calibrated speed-torque region.
Innovation Solution
A motor controller that calibrates the electric motor based on a single speed-to-airflow ratio, using a calibrating speed and airflow to compute an objective speed for low airflow requests, thereby reducing computational errors and maintaining accurate airflow control through linear extrapolation and correction functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional torque-calibration methods are used for motor control, then manufacturing precision is achieved during production, but measurement precision deteriorates at low airflow levels due to parasitic current and noise
Solution Approach 1:
The patent changes the control parameter from torque-based calibration to speed-to-airflow ratio calibration. Instead of relying on torque measurements that are susceptible to parasitic current and noise at low levels, the system uses motor speed and airflow measurements to establish a calibration ratio, fundamentally changing how the system achieves accurate airflow control.
Solution Approach 2:
The patent replaces the mechanical torque measurement system with an electrical control system that uses speed sensing and computational algorithms. The motor controller computes airflow based on speed-to-airflow ratio rather than direct torque measurement, substituting a more accurate measurement approach for the problematic mechanical sensing method.
2Manufacturing precision
If multiple calibration points are used across the speed-torque operating profile, then manufacturing precision is maintained, but device complexity increases
Solution Approach 1:
The patent extracts the essential calibration information into a single speed-to-airflow ratio parameter rather than requiring multiple calibration points across the operating profile. This single ratio captures the relationship between motor speed and airflow output, simplifying the calibration process while maintaining accuracy across different operating conditions.
Solution Approach 2:
The single speed-to-airflow ratio calibration serves multiple functions across the entire operating range of the motor. Rather than requiring separate calibration points for different airflow levels, this universal ratio enables accurate airflow computation whether the motor operates at high speed or low speed, high airflow or low airflow.
3Manufacturing precision
If torque-control mode is used for blower operation, then manufacturing precision is achieved during calibration, but reliability deteriorates at low airflow levels due to error accumulation
Solution Approach 1:
The patent implements a feedback mechanism where the motor controller continuously monitors motor speed and uses the calibrated speed-to-airflow ratio to compute actual airflow output. This closed-loop approach allows the system to maintain accurate airflow control at low levels by continuously adjusting based on measured speed and the established calibration relationship, rather than relying on open-loop torque commands that accumulate error.
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.