Sensorless BLDC Motor Control Using Inductance-Based Failure Detection
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Solution Overview
Problem
Existing methods for determining motor failure in sensorless DC brushless motors require turning on/off multiple switching elements according to various test patterns, leading to prolonged downtime for failure determination processing.
Innovation Solution
A motor control apparatus that includes an excitation unit to excite multiple excitation phases of a motor, a measurement unit to measure physical changes related to coil inductance, and a determination unit to assess the rotor position and potential motor or excitation unit failures based on measured data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple switching elements are turned on/off according to multiple test patterns for failure determination, then the accuracy of failure detection is improved, but the downtime for failure determination processing increases
Solution Approach 1:
The patent performs failure determination processing before the motor is actually driven. By measuring the inductance values of the motor coils in advance (during the M-step before drive control in S100), the system can detect failures before they affect operation. This preliminary measurement approach allows the motor to be driven immediately after determination without waiting for post-drive failure analysis, thus reducing downtime while maintaining detection accuracy.
Solution Approach 2:
The patent extracts the failure determination process from the motor drive operation. Instead of determining failure during or after driving, the system separates the determination step (measuring inductance values) from the drive step. This extraction allows failure determination to be performed independently using only inductance measurements without requiring the motor to be driven, thereby reducing the time loss while maintaining reliable detection.
2Measurement precision
If inductance measurement is performed for each excitation phase to determine rotor position and failure, then the precision of rotor position determination is improved, but the complexity of measurement processing increases
Solution Approach 1:
The patent uses a universal inductance measurement approach that serves multiple functions simultaneously. The same inductance measurement process is used for both failure determination (comparing measured values with reference values) and rotor position determination (identifying the phase with maximum inductance). This multi-functionality allows the system to achieve precise rotor position determination without adding separate measurement systems, thereby managing complexity while improving measurement precision.
Solution Approach 2:
The patent segments the measurement process into distinct phases corresponding to each excitation phase. By measuring inductance values for each phase separately (L1, L2, L3 for phases 1, 2, 3) and comparing them individually, the system can precisely determine rotor position by identifying which phase has the maximum inductance value. This segmentation approach maintains measurement precision while organizing the processing in a manageable, systematic way.
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
This solution enables rapid and accurate determination of motor failure without increasing downtime, by efficiently measuring inductance changes and determining rotor position and potential failures within the motor control apparatus.
Implementation Method 1
a measurement unit configured to measure a physical amount that changes according to an inductance of at least one of a plurality of coils that make up the plurality of excitation phases
Data Source
AI summary
A motor control apparatus includes: an excitation unit configured to excite a plurality of excitation phases of a motor; a measurement unit configured to measure a physical amount that changes according to an inductance of at least one of a plurality of coils that make up the plurality of excitation phases by exciting each of the plurality of excitation phases, and generate measured data that includes measurement values of the physical amount measured for the plurality of excitation phases; and a determination unit configured to determine, based on the measured data, a rotational position of a rotor of the motor and whether or not at least one of the motor and the excitation unit has a failure.