Sensorless Motor Rotor Position Estimation via High-Frequency Injection
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Solution Overview
Problem
Existing sensorless motor driving apparatuses face challenges in accurately estimating the position of a motor rotor without position sensors, which affects efficient motor operation and energy consumption.
Innovation Solution
A motor driving apparatus that includes an inverter to convert DC power to AC power, an output current detector, and a controller that controls the inverter to estimate the rotor position by applying a phase current of a predetermined frequency during a first interval and aligns the rotor based on detected output currents, using d-axis current command values in synchronization reference frames during subsequent intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless control is used to reduce manufacturing costs, then device complexity is reduced, but measurement precision of rotor position deteriorates
Solution Approach 1:
The patent introduces an intermediary high-frequency voltage signal as a mediator to indirectly detect rotor position. By injecting a high-frequency voltage signal and measuring the resulting current response, the system obtains rotor position information without direct sensing, thus maintaining sensorless operation while improving measurement precision.
Solution Approach 2:
The patent replaces mechanical/sensor-based position detection with an electrical field-based method. Instead of using physical sensors to detect rotor position, the system uses high-frequency voltage injection and current measurement to electronically determine position, substituting mechanical detection with electrical measurement.
2Measurement precision
If high-frequency voltage signal is injected to improve rotor position estimation accuracy, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent employs periodic injection of high-frequency voltage signals at specific intervals during motor operation. Rather than continuous injection, the system periodically introduces test signals to obtain position updates, reducing overall energy consumption while maintaining sufficient measurement precision for effective control.
Solution Approach 2:
The patent applies partial action by injecting high-frequency voltage signals only when necessary for position estimation, rather than continuously. The system uses these signals selectively during startup or when position information needs updating, avoiding excessive energy consumption while maintaining adequate measurement precision.
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 accurate and efficient estimation and alignment of the motor rotor position, reducing noise and estimation time, and improving motor operation without the need for position sensors, thereby enhancing energy efficiency and operational accuracy.
Implementation Method 1
an inverter to convert a direct current (DC) power into an alternating current (AC) power through a switching operation
Implementation Method 2
during a first interval after the motor stop, the controller controls a phase current of a predetermined frequency to flow through the motor to estimate a position of a rotor of 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) and the home appliance include an inverter (420) to convert a direct current (DC) power into an alternating current (AC) power through a switching operation and to output the converted AC power to a motor (230), an output current detector (E) to detect an output current flowing through the motor (230), a controller (430) to control the inverter (420), wherein, during a first interval after the motor (230) stops, the controller (430) controls a phase current of a predetermined frequency to flow through the motor (230) to estimate a position of a rotor of the motor (230), and estimates the position of the rotor of the motor (230) based on the detected output current while the phase current of the predetermined frequency flows through the motor (230). Thereby, the sensorless motor driving apparatus (220) can easily estimate the position of the motor rotor.