Hybrid Vehicle Controller Communication Switching for Braking Stability
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Solution Overview
Problem
Conventional hybrid vehicle controllers experience divergence in cooperative braking control during transition states, leading to excessive motor-generator rotation and potential slipping or gripping issues, due to the reliance on a centralized HV ECU for torque calculation and communication relay.
Innovation Solution
The vehicle controller includes an MG ECU that calculates demand torque for motor-generators and selectively switches between communication lines based on travel state determinations, allowing direct communication with the brake ECU during transition states, thereby bypassing the HV ECU relay and maintaining control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the MG ECU calculates demand torque and communicates with the brake ECU via the HV ECU relay (centralized communication), then the system structure is simplified and communication is standardized, but the cooperative control of braking force diverges in transition states causing excessive motor-generator rotation
Solution Approach 1:
The patent applies dynamics by making the communication path adaptable rather than fixed. The MG ECU dynamically selects between direct communication with the brake ECU and relay communication through the HV ECU based on the operational state (normal vs. transition state). This dynamic adjustment of communication topology resolves the contradiction by optimizing for reliability during transition states while maintaining structural simplicity during normal operation.
Solution Approach 2:
The patent segments the communication architecture into two distinct paths: a direct communication channel between MG ECU and brake ECU, and an indirect relay path through the HV ECU. This segmentation allows the system to choose the appropriate communication path based on operational conditions, preventing control divergence during transition states while maintaining overall system simplicity.
2Reliability
If the MG ECU directly communicates with the brake ECU during transition states, then the cooperative control stability is improved and excessive rotation is prevented, but the communication system complexity increases
Solution Approach 1:
The communication system implements dynamic path selection where the MG ECU adjusts its communication strategy based on the detected operational state. During transition states, direct communication is activated for high reliability; during normal states, the system uses the simpler relay path. This dynamic approach achieves high reliability when needed without permanently increasing system complexity.
Solution Approach 2:
The MG ECU is designed with multi-functionality to handle both direct communication and relay communication protocols. This universal capability allows the single MG ECU to adapt to different communication requirements without adding separate dedicated communication devices, thus improving reliability without proportionally increasing system complexity.
Data Source
AI summary
A vehicle controller includes an hybrid vehicle (HV) ECU, a motor-generator (MG) ECU, a brake ECU, a first communication line that enables one-to-one connection between the HV ECU and the MG ECU, and a second communication line that enables connection among plural ECUs including the HV ECU and the brake ECU. The MG ECU calculates an operation torque of first and second MGs. The MG ECU is communicable with the brake ECU via the second communication line. In addition, the controller includes a microcomputer that serves as a travel state determiner for determining whether a travel state of a hybrid vehicle is a transition state in which a drive wheel alternatively slips and grips. Based on a determination result of the microcomputer, the controller switches to the first communication line in a normal state and to the second communication line in the transition state.