Mild Hybrid Starter Control for Cold Start Efficiency
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Solution Overview
Problem
Mild hybrid starter generators (MHSG) in 48 V systems face efficiency limitations and belt slip issues during cold starting, particularly due to the reliance on engine starting conditions and outdoor temperatures in conventional control methods.
Innovation Solution
A method and apparatus that measure cooling water temperature to determine when to engage a starter and transition from starter-driven engine operation to MHSG-driven operation once the engine reaches a preset RPM, allowing for stepwise starting and optimizing engine startability in cold conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MHSG is used to drive the engine during cold starting, then the belt slip and efficiency limitations occur, but if the starter is used, then the cold starting capability is improved
Solution Approach 1:
The system performs preliminary warming of the engine using the starter motor before transitioning to MHSG operation. The control method determines when the engine has reached sufficient temperature and RPM conditions, then switches from starter-driven to MHSG-driven operation, ensuring the MHSG operates under favorable conditions that prevent belt slip and efficiency loss
Solution Approach 2:
The system dynamically switches between two driving modes (starter and MHSG) based on real-time engine conditions. The control method continuously monitors engine parameters and transitions from starter operation to MHSG operation when predetermined conditions are met, optimizing performance across varying operating conditions
2Reliability
If the starter operates until high RPM is reached, then the cold starting is successful, but the transition to MHSG operation is delayed
Solution Approach 1:
The control method determines in advance the optimal transition point by monitoring engine RPM and temperature conditions. When the engine reaches predetermined RPM thresholds during cranking, the system prepares for and executes the transition to MHSG operation, minimizing the time the starter needs to operate while ensuring successful engine start
Data Source
AI summary
An apparatus and method for controlling cold starting of a mild hybrid vehicle, are disclosed. The method includes: measuring, by a sensor, a cooling water temperature of the vehicle when a request is received to start an engine; operating, by a controller, a starter to drive an engine when the cooling water temperature is less than a preset reference temperature, and stopping the operation of the starter and operating an MHSG to drive the engine when RPM of the engine driven by the starter exceeds a preset reference value. In particular, stepwise starting according to the cold starting of the vehicle is performed. The apparatus and the method are advantageous in that a starter and alternator are simultaneously controlled under a cold starting condition to provide startability and reduce capacity of a starter, reducing manufacturing costs.