Sensorless Motor Drive Bootstrap Control for Stop Detection
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Solution Overview
Problem
Sensorless motor driving apparatuses face challenges in conveniently determining whether a motor has stopped, particularly during rheostatic braking, as existing methods require significant time and are not immediately effective in restarting the motor.
Innovation Solution
A motor driving apparatus comprising 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 and restarting 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 conveniently determine motor stoppage deteriorates
Solution Approach 1:
The patent uses DC link voltage as an intermediary parameter to indirectly detect motor stoppage. Instead of directly measuring motor position or speed (which would require sensors), the system monitors the DC link voltage behavior during rheostatic braking to infer whether the motor has stopped, thus maintaining sensorless operation while enabling stoppage detection
Solution Approach 2:
The system implements feedback by continuously monitoring DC link voltage and comparing it against reference values or change thresholds. This feedback mechanism allows the controller to determine motor stoppage based on voltage stabilization patterns during braking, enabling automatic control decisions without additional sensors
2Reliability
If conventional stoppage determination methods are used, then motor stoppage can be detected, but significant time is required and immediate restarting is not possible
Solution Approach 1:
The system performs preliminary monitoring of DC link voltage changes during the braking process itself. By analyzing voltage behavior in real-time during rheostatic braking, the controller can determine stoppage immediately when voltage stabilization criteria are met, eliminating the need for separate post-braking waiting periods and enabling immediate 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 and restarting, eliminating the need for separate time assessments and improving operational efficiency in sensorless motor control.
Implementation Method 1
a dc link capacitor configured to store a direct current (DC) voltage
Implementation Method 2
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 3
a motor configured to receive the AC voltage from the inverter and rotate in response thereto
Implementation Method 4
the controller controls rheostatic braking to be performed in order to stop the motor
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).