Motor Control Apparatus for Rotor Stop Position Detection
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Solution Overview
Problem
Sensorless DC brushless motors face challenges in detecting the rotor stop position due to slow attenuation of exciting current, leading to prolonged detection times and potential synchronization loss or backward rotation.
Innovation Solution
A motor control apparatus that applies a first voltage of one polarity to a coil for a period and then a second voltage of opposite polarity, with integrated duty cycles to efficiently attenuate the exciting current, allowing for quicker detection of the rotor stop position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurement is performed for combinations of a plurality of coils to correctly detect the rotor stop position, then the detection accuracy is improved, but the detection time becomes excessively long due to slow exciting current attenuation
Solution Approach 1:
The patent applies periodic voltage with alternating polarity to the coil during the detection process. By switching the voltage polarity periodically, the exciting current is forced to attenuate faster through the alternating excitation and de-excitation cycles, enabling multiple coil measurements to be completed within a shorter overall time while maintaining detection accuracy
Solution Approach 2:
The patent changes the voltage polarity parameter during the detection process. By alternating between positive and negative voltage polarity, the system accelerates the exciting current attenuation and enables faster sequential measurement of multiple coils without compromising the precision of rotor stop position detection
2Measurement precision
If the exciting current attenuation is slow, then the measurement can be performed accurately, but the waiting time until the exciting current becomes zero takes a long time
Solution Approach 1:
The patent uses periodic voltage application with alternating polarity to accelerate current attenuation. The periodic switching creates controlled excitation and de-excitation cycles that force the current to reach zero faster, reducing waiting time while maintaining measurement precision through proper timing of the periodic cycles
Solution Approach 2:
The patent applies voltage of opposite polarity as a preliminary anti-action to counteract the slowly attenuating exciting current. By applying reverse polarity voltage before the current naturally decays to zero, the system actively forces the current to zero faster, reducing the waiting time without sacrificing measurement accuracy
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 approach reduces the waiting time for rotor stop position detection and suppresses abnormal noise, enabling faster motor initialization and preventing synchronization issues.
Implementation Method 1
a voltage control unit configured to control a voltage applied to a plurality of coils included in a motor to supply an exciting current to the plurality of coils
Data Source
AI summary
A motor control apparatus includes: a voltage control unit configured to control a voltage applied to a plurality of coils in a motor to supply an exciting current; a current detection unit configured to detect an exciting current having flown through the plurality of coils; and a detection unit configured to detect a stop position of a rotor of the motor by performing a detection process, in which the exciting current to at least a first coil of the plurality of coils is supplied by the voltage control unit, and the exciting current is detected by the current detection unit. The detection process includes a first period in which a first voltage of a first polarity is applied to the first coil, and a second period in which a second voltage of a second polarity is applied to the first coil.