Sensorless Motor Drive Stoppage Detection Via DC-Link Voltage
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Solution Overview
Problem
Existing sensorless motor driving apparatuses face challenges in conveniently determining whether a motor has stopped, particularly during rheostatic braking, as it is difficult to accurately assess the motor's state using existing methods which require separate determination times and may not immediately address motor restarting.
Innovation Solution
A motor driving apparatus incorporating a dc link capacitor, an inverter with upper and lower arm switching elements, a dc link voltage detector, an output current detector, and a controller that performs rheostatic braking and bootstrap operations to determine motor stoppage based on detected voltage and current changes, allowing for immediate determination of motor rotation or stoppage without additional time requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensorless control is used to reduce manufacturing cost, then manufacturing cost is reduced, but the ability to accurately determine motor stoppage is worsened
Solution Approach 1:
The patent uses DC link voltage as an intermediary parameter to indirectly determine motor stoppage. Instead of directly measuring motor position or speed (which would require sensors), the system monitors the DC link voltage which changes predictably when the motor stops, providing accurate stoppage detection without additional sensors.
Solution Approach 2:
The system uses existing components (DC link capacitor and voltage detector) already present in the motor drive circuitry to determine motor stoppage. The DC link voltage naturally changes when motor current changes, and the system leverages this self-generated signal for stoppage detection without requiring external sensors or additional measurement systems.
2Measurement precision
If separate determination time is used to assess motor state, then measurement accuracy is improved, but response time for motor restarting is worsened
Solution Approach 1:
The system continuously monitors the DC link voltage during operation, so when the motor stops, the voltage change is immediately detected without requiring a separate measurement phase. This continuous monitoring eliminates dead time between motor stopping and detection, enabling immediate restarting capability while maintaining accurate detection.
Solution Approach 2:
The DC link voltage is continuously tracked before motor stoppage occurs, so when the motor stops, the system already has current voltage data ready for immediate analysis. This preliminary continuous measurement eliminates the need for separate determination time, allowing instant detection and rapid motor restarting.
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
Enables convenient and immediate determination of motor stoppage, facilitating efficient motor control and restarting by utilizing detected voltage and current changes, thus improving the sensorless motor driving apparatus's ability to manage motor states effectively.
Implementation Method 1
an inverter including a plurality of upper and lower arm switching elements and configured to convert the voltage stored in the dc link capacitor into an alternating current (AC) voltage by switching operation of the switching elements
Implementation Method 2
a dc link capacitor configured to store a direct current (DC) voltage
Implementation Method 3
an output current detector provided between the dc link capacitor and the inverter and configured to detect output current flowing in the motor
Implementation Method 4
a dc link voltage detector configured to detect the voltage of the dc link capacitor
Data Source
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AI summary
Disclosed herein are a motor driving apparatus (220) and a home appliance including the same. The motor driving apparatus (220) includes a dc link capacitor (C), an inverter (420), a dc link voltage detector (B), and a controller (430). The controller (430) controls rheostatic braking to be performed in order to stop the motor (230), performs bootstrap operation of gate terminals of the upper arm switching elements (Sa, Sb, Sc) of the inverter (420) during a first period for starting the motor (230), and determines whether the motor (230) stops during the first period based on the dc link voltage detected by the dc link voltage detector (B) or the output current detected by the output current detector (E). Accordingly, it is possible to conveniently determine whether the motor (230) stops in the sensorless type motor driving apparatus (220).