Starter-Generator Rotor Position Detection Without Hall Sensors
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Solution Overview
Problem
The existing ACG starter motors for small two-wheeled vehicles require high mounting accuracy for hall sensors to detect rotor position, increasing manufacturing time and cost, and alternative methods like using a sub-coil for rotor position detection during 180° conduction are cumbersome.
Innovation Solution
A starting power generation apparatus that uses a control unit with MOSFETs and power conversion units to detect rotor position without a sub-coil or expensive sensors by sequentially conducting short pulses to the windings and determining the rotor stage based on induced voltages, allowing for accurate positioning without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hall sensors are arranged for each winding of each phase to detect rotor position, then rotor position detection accuracy is improved, but manufacturing complexity and cost increase due to high mounting accuracy requirements and additional mounting processes
Solution Approach 1:
The patent extracts the rotor position detection function from the hall sensor system and implements it through software-based detection using voltage induced in the non-conduction phase windings. This eliminates the need for physical hall sensors and their complex mounting processes, thereby reducing manufacturing complexity while maintaining detection accuracy.
Solution Approach 2:
The patent replaces the mechanical hall sensor system with an electrical/software-based detection method. Instead of using physical sensors that require precise mechanical mounting, the system uses voltage induction principles and computational algorithms to detect rotor position, thereby eliminating mechanical complexity.
2Measurement precision
If hall sensors are used for rotor position detection, then detection accuracy is improved, but product cost increases due to high sensor prices and additional mounting processes
Solution Approach 1:
The patent replaces expensive hall sensors with a cost-effective software-based detection method that utilizes existing windings and control circuitry. This eliminates the need to purchase and install costly sensors, significantly reducing product manufacturing costs while maintaining functional equivalence.
Solution Approach 2:
The system uses its own existing windings and voltage induction characteristics to perform rotor position detection, eliminating the need for external sensors. The control unit leverages the motor's inherent electrical properties for self-detection, reducing component costs.
3Difficulty of detecting and measuring
If a sub-coil is attached to detect rotor position during 180° conduction, then rotor position detection is enabled, but device complexity increases due to additional hardware requirements
Solution Approach 1:
The patent makes the existing windings serve dual functions: both as motor windings for operation and as detection windings for rotor position detection. The non-conduction phase windings are utilized for detection purposes without requiring separate dedicated detection coils, thereby eliminating additional hardware complexity.
Solution Approach 2:
The patent merges the motor function and detection function into a single integrated system. The same windings that produce motor torque also generate the induced voltages used for rotor position detection, eliminating the need for separate sub-coils or detection hardware.
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 cost-effective and simple rotor position detection, reducing manufacturing complexity and costs while maintaining accurate positioning, and optimizing power generation and load balance.
Implementation Method 1
determining a rotor position based on a voltage induced in a non-conduction phase when a short pulse is sequentially conducted to the other two phases
Data Source
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AI summary
Provided are: a starter generator including a field portion having a permanent magnet, and an armature unit including a first multi-phase winding and a second multi-phase winding which are arranged in parallel; a first power conversion unit including a first positive-side DC terminal connected to a battery and a plurality of first AC terminals connected to the first multi-phase winding, the first power conversion unit being configured to convert a power bidirectionally between DC and AC; a second power conversion unit including a plurality of second AC terminals connected to the second multi-phase winding, the second power conversion unit being configured to control a current to be input and output via the second AC terminals; and a control unit configured to detect a positional relationship between the field portion and the armature unit based on an output voltage of the second multi-phase winding, and control the first power conversion unit and the second power conversion unit in accordance with the detected positional relationship.