BSG Belt Loss Torque Split Control in Multi-Motor Powertrains
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Solution Overview
Problem
Conventional torque control systems for electrified vehicles do not account for belt-based losses in FEAD or BSG systems, leading to inaccurate torque calculations and non-optimal motor torque splits, especially in multi-motor configurations, with the only conventional solution being to increase engine torque, which is suboptimal.
Innovation Solution
A torque control system that estimates belt torque loss based on stored data and engine speed, determines an optimized torque split between electric motors to minimize battery power, and controls the powertrain accordingly, using a quadratic fit for motor speed and a 'donut-shaped region' to find the optimal torque split.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional torque control systems increase engine torque to compensate for belt losses, then the torque accuracy is improved, but the device complexity and energy efficiency worsen due to suboptimal multi-motor torque split
Solution Approach 1:
The system pre-characterizes belt losses during engine calibration by measuring torque at the engine output and BSG input across various operating conditions. This preliminary characterization stores loss data that is later used to compensate for belt losses in real-time torque calculations, eliminating the need for complex real-time measurements and simplifying the control system while maintaining accuracy
Solution Approach 2:
The system implements feedback by using the characterized belt loss data to continuously adjust and optimize the torque split between the engine and BSG. The control system uses the stored loss characteristics to determine accurate torque requirements, creating a closed-loop system that maintains optimal torque distribution without increasing overall system complexity
2Measurement precision
If conventional torque control systems increase engine torque to account for belt losses, then torque accuracy is improved, but energy efficiency worsens due to non-optimal multi-motor torque split
Solution Approach 1:
The system pre-characterizes belt losses during engine calibration by measuring torque at the engine output and BSG input across various operating conditions. This preliminary characterization stores loss data that is later used to compensate for belt losses in real-time torque calculations, eliminating the need for complex real-time measurements and simplifying the control system while maintaining accuracy
Solution Approach 2:
The system implements feedback by using the characterized belt loss data to continuously adjust and optimize the torque split between the engine and BSG. The control system uses the stored loss characteristics to determine accurate torque requirements, creating a closed-loop system that maintains optimal torque distribution without increasing overall system complexity
Data Source
AI summary
Torque control techniques for a multi-motor electrified powertrain of an electrified vehicle include determining a total torque request to be satisfied by the multi-motor electrified powertrain, wherein a first electric motor is connected to a crankshaft of an engine via a belt as part of a belt-driven starter-generator (BSG), estimating a torque loss associated with the belt based on stored data and an engine speed or a BSG speed, determining an optimized torque split of the total torque request between the first electric motor and a second electric motor based on the estimated belt torque loss and to minimize battery power, determining torque commands for the engine and the first and second electric motors based on the determined optimized torque split, and controlling the multi-motor electrified powertrain based on the determined torque commands for the engine and the first and second electric motors.