Electric Machine Switch-on Frequency Control for Turbocharger Reliability
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Solution Overview
Problem
The existing technologies for controlling charge-air pressure in exhaust-gas turbochargers do not effectively manage the stress factors affecting electric machines, such as temperature and power consumption, leading to reduced service life due to frequent switch-on operations during boost and recuperative operations.
Innovation Solution
A method and device that limit the switch-on frequency of the electric machine based on operating parameters, such as mileage, number of switch-on operations, and control variances, with separate threshold values for boost and recuperative operations, and a weighting factor to prioritize one mode over the other, ensuring the electric machine's service life is aligned with the vehicle's lifespan while preventing emissions violations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electric machine is frequently switched on during boost and recuperative operations to control charge-air pressure, then the charge-air pressure control precision is improved, but the service life of the electric machine is reduced due to stress factors such as temperature and power consumption
Solution Approach 1:
The patent applies dynamics by making the threshold value for switching on the electric machine adaptive rather than fixed. The control unit adjusts the threshold value dynamically based on the actual switch-on frequency and a target switch-on frequency, allowing the system to balance pressure control precision with machine longevity. This dynamic adjustment resolves the contradiction by enabling the system to maintain adequate control precision while limiting excessive switching that would reduce service life
Solution Approach 2:
The patent changes the parameter of the switch-on threshold value based on operating conditions and accumulated switch-on frequency. By modifying this critical parameter adaptively, the system can tolerate higher control variance when the electric machine has been switched on frequently, thereby reducing further switching events and protecting the machine's service life while maintaining acceptable charge-air pressure control
2Reliability
If the switch-on threshold for the electric machine is lowered to extend service life, then the switch-on frequency is reduced and service life is extended, but the charge-air pressure control may become insufficient
Solution Approach 1:
The patent dynamically adjusts the switch-on threshold parameter based on the actual switch-on frequency relative to the target frequency. When the actual frequency exceeds the target, the threshold is adapted to reduce further switching, thereby extending service life. The system maintains acceptable control precision by allowing increased variance when switching is limited, optimizing the trade-off between reliability and control precision
Data Source
AI summary
A method for protecting an electric machine of a motor vehicle, In the method, a switch-on frequency for the electric machine is ascertained as a function of operating parameters of the motor vehicle stored in a control unit. The switch-on frequency is compared to a predefinable first threshold value. At least one further threshold value is preset. The electric machine is switched on in the event a control variance exceeds the at least one further threshold value. In the event the switch-on frequency exceeds the first predefinable threshold value, the at least one further threshold value is adapted in such a way that the switch-on frequency of the electric machine is limited.