Hybrid Vehicle Angular Position Sensing Without Absolute Motor Sensor
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Solution Overview
Problem
In hybrid vehicles with internal combustion engines and electric machines, existing technologies face challenges in accurately detecting the angular position between the engine and electric machine, leading to inefficiencies in reducing vibration excitations, particularly due to the lack of an absolute angle sensor for the electric machine and reliance on software-selected reference poles which can become invalid.
Innovation Solution
An angular position detection device with a crankshaft sensor for the internal combustion engine and a rotor position sensor for the electric machine, utilizing electronic control units to determine and store the mechanical angular reference between the two, incorporating a learning function to establish an initial reference and an adjustment function to correct for pole shifts and inaccuracies, thereby enabling accurate communication and vibration reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a software-selected reference pole is used for the electric machine instead of an absolute angle sensor, then device complexity is reduced, but measurement precision deteriorates because the reference pole can become invalid
Solution Approach 1:
The control unit continuously monitors the angular position relationship between the internal combustion engine and electric machine, comparing detected positions against the stored mechanical angular reference. When deviations exceed thresholds indicating pole shift, the system provides feedback to correct the reference pole selection, maintaining measurement precision without adding absolute sensors.
Solution Approach 2:
The system performs self-calibration by detecting the mechanical angular reference during stationary conditions and automatically adjusting the reference pole selection. The control unit uses the relationship between engine crankshaft position and electric machine rotor position to identify and correct pole shifts without external intervention or additional hardware.
2Reliability
If the mechanical angular reference is continuously adjusted at each start and stop, then reliability is improved through error correction, but loss of time increases due to repeated calibration operations
Solution Approach 1:
The system performs partial calibration by only adjusting the mechanical angular reference when necessary conditions are met (stationary detection, fault conditions, or exceeding angular thresholds). Instead of recalibrating at every single start-stop cycle, the system applies correction only when measurement deviations indicate pole shift, reducing time loss while maintaining reliability.
3Measurement precision
If the absolute angular position of the internal combustion engine and relative angular position of the electric machine are detected when stationary, then measurement precision is improved, but loss of time increases due to additional detection operations
Solution Approach 1:
The system performs preliminary detection of absolute engine angular position and relative electric machine angular position during stationary periods before operation begins. This preliminary action establishes the mechanical angular reference in advance, allowing precise angle/revolution rate information to be available immediately when the engine starts without requiring continuous additional detection operations during runtime.
Data Source
AI summary
An angular position detection device in a hybrid vehicle includes a crankshaft sensor for detecting an absolute internal combustion engine angular position with respect to a defined position mark, an electric machine, a rotor position sensor for detecting a relative electric machine angular position based on a reference point, in particular a reference pole comprising a plurality of identical rotor poles, and an electronic control unit. The control unit is configured such that the absolute internal combustion engine angular position and the relative electric machine angular position are detected when the internal combustion engine is stationary and the electric machine is stationary, and a mechanical angular reference of the internal combustion engine with respect to the electric machine is determined, on the basis of these angular positions, as an angle difference between the position mark and an initial reference point.