Sensorless Motor Inverter Alignment for Stator Parameter Estimation
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Solution Overview
Problem
Sensorless motor driving apparatuses face challenges in accurately calculating stator resistance and inductance during motor alignment, which is crucial for efficient motor operation, especially in reducing manufacturing costs and improving performance without relying on position sensing units.
Innovation Solution
A motor driving apparatus that includes an inverter controller capable of controlling currents with DC and high-frequency components during specific alignment periods, allowing for the calculation of stator resistance and inductance by removing high-frequency and DC components from supplied currents, enabling efficient motor alignment and operation without position sensing units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensorless type motor driving apparatus is used to reduce manufacturing cost, then manufacturing cost is reduced, but measurement precision of stator resistance and inductance during alignment deteriorates
Solution Approach 1:
The patent applies preliminary action by performing stator resistance and inductance measurements during the motor alignment period before normal operation begins. The controller supplies specific test currents (including DC and high-frequency components) during this preliminary phase to accurately measure motor parameters, ensuring precise measurements are obtained before the sensorless control mode starts, thus resolving the measurement accuracy issue while maintaining cost reduction
2Measurement precision
If current signals with DC and high-frequency components are supplied during alignment period, then measurement precision of stator parameters is improved, but device complexity increases
Solution Approach 1:
The patent applies periodic action by confining the complex current supply operations to a specific periodic phase - the alignment period - rather than continuous operation. During this limited time window, the controller supplies test currents with DC and high-frequency components to measure parameters, then transitions to normal sensorless operation. This temporal limitation reduces overall device complexity while maintaining measurement precision when needed
Data Source
AI summary
A motor driving apparatus includes an inverter to convert a direct current (DC) voltage into an alternating current (AC) voltage through a switching operation and to output the AC voltage to a motor, an output current detector to detect an output current flowing in the motor, and a controller to control the inverter, wherein, at the time of starting the motor, the controller controls a first current, including a DC component and a high-frequency component, to be supplied to the motor during a first period for alignment of the motor, and controls a second current, including a DC component and a high-frequency component, to be supplied to the motor during a second period for alignment of the motor, and the controller calculates the stator resistance and inductance of the motor based on the first current and the second current. Consequently, it is possible to easily calculate the stator resistance and inductance of the motor during the alignment of the motor.