Blower Motor Hall Sensor Correction Using Induced Voltage Learning
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Solution Overview
Problem
Motor control devices face challenges in constantly correcting position errors in rotation sensors, which can lead to noise and performance issues due to mounting errors and aged deterioration of Hall elements.
Innovation Solution
A motor control device with a microcontroller, inverter circuit, Hall element, comparator, and voltage dividing circuit that acquires and corrects position errors by detecting induced voltages in stator coils during low-speed rotation, using a learn value to adjust the position of the rotor magnet relative to the Hall sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position error correction is performed using inertial rotation period detection, then position error can be corrected, but correction cannot be performed at low rotation speeds where inertial rotation cannot be generated
Solution Approach 1:
The patent changes the detection parameter from inertial rotation period to induced voltage characteristics. By detecting induced voltage during low-speed rotation and analyzing its waveform characteristics, the system can determine rotor position and perform correction learning even at rotation speeds where inertial rotation cannot be generated, thus expanding the applicable rotation speed range while maintaining correction accuracy
2Measurement precision
If correction learning is performed frequently to maintain accuracy, then position error is constantly corrected, but motor operation time is reduced and productivity decreases
Solution Approach 1:
The patent performs correction learning in advance during low-speed rotation periods (such as during acceleration or deceleration phases) before the motor enters high-speed operation. By completing the correction learning beforehand, the system ensures accurate position detection for subsequent high-speed operation without requiring frequent interruptions, thus maintaining correction accuracy while maximizing motor operation time
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 device effectively suppresses noise and maintains motor performance by constantly correcting position errors, ensuring quiet operation and accurate rotor positioning even with mounting errors or aged Hall element variations.
Implementation Method 1
a Hall element 41 that detects a position of the rotor magnet 32
Implementation Method 2
a comparator 42 that compares the detection signal from the Hall element 41 with a learn value and generates a corrected detection signal
Implementation Method 3
an inverter circuit 20 that controls energization of a stator coil 31
Implementation Method 4
calculates a duty ratio based on a rotation speed and a rotation position of the rotor
Data Source
AI summary
A blower motor control device stops energization to a motor when a rotation speed of a rotor reaches a learn rotation speed, and acquires a correction amount as a new learn value for correcting a position error of the rotor relative to a Hall element by using an induced voltage in a coil of the motor and a detection signal from a rotation sensor. The blower motor control device stores the new learn value in a ROM. The blower motor control device corrects the position error by using a previous learn value read from the ROM, for energization control of the motor, until the rotation speed reaches the learn rotation speed.