Compound Boosting Control for Engine Transient Response
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Solution Overview
Problem
Existing engine systems with compound boosting configurations, such as those using both turbochargers and electric superchargers, face inefficiencies due to static boost control methods that do not dynamically adjust pressure ratios, leading to reduced fuel economy, slower boost response, and missed energy recuperation opportunities.
Innovation Solution
Implementing a dynamic boost control method that adjusts the operation of intake compression devices based on target boost pressures, using positive and negative torque from an electric motor to optimize the performance of both the turbocharger and electric supercharger, and employing a lead compensator to reduce pressure overshoot and maximize energy recuperation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If static boost control methods with predefined calibrations are used to determine desired partial pressure ratios, then the control system is simple to implement, but the fuel economy deteriorates due to longer than required supercharger operation duration
Solution Approach 1:
The patent implements dynamic boost control that continuously adjusts the desired partial pressure ratios based on real-time operating conditions rather than relying on static predefined calibrations. The controller dynamically coordinates between turbocharger and supercharger based on actual boost pressure feedback, optimizing the supercharger shutdown timing to improve fuel economy while maintaining system simplicity through coordinated control logic.
2Stability of the object's composition
If conservative pressure ratios are commanded to each compression device to minimize boost pressure overshoot, then the system stability is improved, but the boost response becomes slower
Solution Approach 1:
The patent employs feedback control where the controller continuously monitors actual boost pressure and dynamically adjusts the desired partial pressure ratios for both turbocharger and supercharger. This feedback mechanism allows the system to respond quickly to boost demands while maintaining stability by adjusting pressure ratio commands based on real-time conditions rather than using fixed conservative values.
3Reliability
If exhaust waste-gate is opened to correct boost pressure overshoot, then the boost pressure control is improved, but the energy recuperation opportunity is lost
Solution Approach 1:
The patent applies preliminary action by dynamically adjusting the desired partial pressure ratios and coordinating supercharger shutdown timing before boost pressure overshoot occurs. The controller predicts and prevents overshoot conditions by optimizing the transition from supercharger-assisted to turbocharger-only operation, eliminating the need for corrective waste-gate opening and preserving energy recuperation opportunities.
4Power
If the turbocharger is upsized to increase peak power and torque performance, then the engine power capability is improved, but the transient response becomes slower
Solution Approach 1:
The patent combines a large turbocharger with an electric supercharger in a compound boosting system. The oversized turbocharger provides peak power capability while the electric supercharger compensates for transient response limitations by providing immediate boost support during transient conditions. The coordinated control of both devices optimizes the balance between peak power and transient response.
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 allows for faster achievement of target boost pressures with improved transient response and reduced fuel consumption by dynamically allocating pressure ratios and optimizing the use of electric assistance, thereby enhancing engine efficiency and energy recovery.
Implementation Method 1
commanding positive torque from an electric motor to a second intake compression device
Implementation Method 2
commanding negative torque from the electric motor to the second intake compression device
Implementation Method 3
Turbochargers and superchargers compress intake air entering the engine using an intake compressor
Data Source
AI summary
Methods and systems are provided for coordinated control of a compound boosting system, including a first compressor staged upstream of a second compressor in an engine intake. In one example, a method may include operating the second, downstream compressor in steady-state to achieve an overall pressure ratio across the compound boosting system while operating the first, upstream compressor transiently, based on an airflow shortfall at the downstream compressor. A timing and amount of electric assistance provided to transiently operate the first, upstream compressor may be adjusted dynamically as the pressure ratio across the second compressor changes.