Starter Generator Rotor Position Detection via Voltage Time Widths
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Solution Overview
Problem
Conventional starter motor systems for vehicles, particularly small two-wheeled vehicles, face challenges in downsizing and reducing costs due to the complexity and power loss associated with current detection circuits used in rotor position detection.
Innovation Solution
A starting power generation apparatus featuring a starter generator with a permanent magnet field and multi-phase windings, utilizing a control unit to detect the positional relationship between the field and armature units based on output voltage, eliminating the need for current detection by applying predetermined voltages to the windings and comparing time widths to determine the rotor position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current detection circuit is used for rotor position detection, then measurement precision is improved, but device complexity increases and power loss increases
Solution Approach 1:
The patent replaces the electrical current detection circuit with a voltage detection method. Instead of measuring current flow in the windings to determine rotor position, the system applies voltage to specific windings and detects the induced voltage in other windings, substituting a simpler voltage measurement approach for the more complex current measurement system.
Solution Approach 2:
The patent introduces an intermediary detection method where voltage application and voltage detection are used as intermediate steps to infer rotor position. Rather than directly measuring current (which requires complex circuits), the system uses voltage as an intermediary signal that can be measured with simpler circuits to indirectly determine the rotor position through the relationship between applied voltage and induced voltage.
2Measurement precision
If current detection circuit is used for rotor position detection, then measurement precision is improved, but power loss increases
Solution Approach 1:
The patent replaces the electrical current detection circuit with a voltage detection method. Instead of measuring current flow in the windings to determine rotor position, the system applies voltage to specific windings and detects the induced voltage in other windings, substituting a simpler voltage measurement approach for the more complex current measurement system.
3Measurement precision
If hall sensors are provided for rotor position detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the hall sensors from the system. Instead of using physical sensors mounted on the rotor to directly detect position, the invention removes these sensors entirely and uses the electrical characteristics of the windings themselves (voltage induction relationships) to determine rotor position, thereby simplifying the overall device structure.
Solution Approach 2:
The patent replaces the mechanical/electrical sensor system (hall sensors) with an electrical field-based detection method. Instead of using physical sensors that require mounting and wiring, the system uses voltage detection and comparison methods that leverage the inherent electromagnetic properties of the motor windings to infer rotor position.
4Measurement precision
If hall sensors are provided for rotor position detection, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent extracts and eliminates the hall sensors from the system. Instead of using physical sensors mounted on the rotor to directly detect position, the invention removes these sensors entirely and uses the electrical characteristics of the windings themselves (voltage induction relationships) to determine rotor position, thereby simplifying the overall device structure.
Solution Approach 2:
The patent replaces expensive, delicate hall sensors with a simpler, more robust voltage detection method that uses basic electronic components already present in the motor control circuitry. This substitution with cheaper, more durable elements reduces manufacturing costs while maintaining detection functionality.
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 allows for accurate rotor position detection without the need for expensive sensors, reducing power loss and complexity, thereby enabling cost-effective and efficient operation.
Implementation Method 1
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 positional relationship detected. The control unit is configured to detect the positional relationship when the starter generator is stopped, based on time widths of two or more predetermined voltages generated in two or more windings constituting the second multi-phase winding in a case that an output voltage of the battery is applied to the first multi-phase winding
Data Source
AI summary
A starting power generation apparatus according to an embodiment of the present invention includes: 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 positional relationship detected. The control unit is configured to detect the positional relationship when the starter generator is stopped, based on time widths of two or more predetermined voltages generated in two or more windings constituting the second multi-phase winding in a case that an output voltage of the battery is applied to the first multi-phase winding for a predetermined time in a state where current input and output via the second AC terminals is off.