Hybrid Powertrain Crank Angle Determination via Resolver Correction
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Solution Overview
Problem
Existing hybrid powertrain control systems face challenges in accurately determining the rotational position of an internal combustion engine crankshaft, particularly during engine restart, due to manufacturing variations and twisting of components, which affects torque variations and alignment of position sensors like resolvers.
Innovation Solution
A control system that determines engine crank angle position based on signal inputs from electric machines, using a control scheme that calculates the input shaft angle and angular twist to correct for offset and twist, allowing precise engine crank angle determination through a combination of resolver measurements and mechanical gear ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resolver is used to measure rotor position in electric machines, then measurement precision is improved, but manufacturing precision deteriorates due to alignment difficulties during installation
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in lookup tables before the engine operates. The microcontroller uses these pre-computed correction values to adjust resolver measurements, eliminating the need for precise manual alignment during installation while maintaining measurement accuracy.
Solution Approach 2:
The patent implements feedback by continuously comparing resolver measurements against reference values and applying real-time corrections. The microcontroller monitors the relationship between input shaft angle and engine crankshaft angle, automatically adjusting for misalignment through stored correction data, thereby maintaining precision without requiring perfect initial alignment.
2Ease of manufacture
If mechanical components are assembled with standard tolerances to improve ease of manufacture, then manufacturing cost is reduced, but measurement precision deteriorates due to cumulative alignment errors
Solution Approach 1:
The patent introduces an intermediary computational system that mediates between imprecise mechanical components and the requirement for precise measurement. The microcontroller acts as an intermediary by processing resolver signals and applying correction algorithms, effectively decoupling the precision requirement from the mechanical assembly tolerances.
Solution Approach 2:
The patent changes the parameter of measurement precision from being dependent on mechanical alignment to being dependent on computational correction. By transforming the problem from a mechanical precision issue to an software correction issue, the system can use standard tolerance components while achieving high measurement accuracy through parameter adjustment and calibration.
3Use of energy by moving object
If the engine is deactivated and unfueled to improve fuel efficiency, then energy consumption is reduced, but reliability deteriorates due to loss of rotational position data
Solution Approach 1:
The patent applies copying by creating and maintaining a computational model of the engine crankshaft position that persists even when the engine is off. The microcontroller preserves the last known good position data and uses correction algorithms to maintain an accurate representation of crankshaft angle, enabling reliable restart without requiring the engine to remain running.
Solution Approach 2:
The system performs preliminary action by pre-calculating and storing correction values and position data before the engine shutdown occurs. This allows the system to maintain reliable position information through the off-state by having prepared correction data ready for when the engine restarts, eliminating the need to keep the engine running solely for data maintenance.
Data Source
AI summary
A control system for a hybrid powertrain which determines engine crank angle position based upon signal inputs from electric machines of the powertrain is provided. The hybrid powertrain comprises an internal combustion engine and electric machines and an electro-mechanical transmission selectively operative to transmit torque therebetween. The electric machines are rotatably fixedly coupled to the internal combustion engine via a transmission input shaft. Control modules are adapted to execute a control scheme to determine engine crank angle position. The control scheme comprises code to determine an input shaft angle based upon rotational positions of the electric machines. An offset angle of the input shaft and an angular twist between the engine and the transmission are determined. An engine crank angle offset is determined based upon the offset angle and the angular twist of the input shaft.