Hybrid EV Drive Mode Control for Torque Fluctuation Stability
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Solution Overview
Problem
Frequent switching between series and parallel drive modes occurs in hybrid electric vehicles when torque demand fluctuates near the maximum torque that the drive motor can provide, leading to inefficiencies.
Innovation Solution
A method and device that utilize an engine economic zone and a power assistance reserve zone to determine the drive mode, maintaining the hybrid electric vehicle in parallel drive mode when torque demand is within these zones and switching to series drive mode only when necessary, thereby reducing frequent mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the vehicle control unit switches between series and parallel modes based on torque demand fluctuations near the maximum torque that the drive motor can provide, then the vehicle can respond to varying power demands, but frequent mode switching occurs leading to system inefficiency
Solution Approach 1:
The patent segments the torque demand range into three distinct zones: first torque demand range (below minimum torque of engine economic zone), second torque demand range (within engine economic zone), and third torque demand range (above maximum torque of engine economic zone). This segmentation allows the system to apply different control strategies to different operating conditions, preventing frequent mode switching at boundary conditions while maintaining adaptability to varying power demands.
2Loss of energy
If the vehicle operates in parallel drive mode when torque demand is within the engine economic zone, then fuel efficiency is improved, but when torque demand fluctuates near the zone boundaries, mode switching frequency increases
Solution Approach 1:
The patent applies local quality by defining specific control rules for different torque demand zones. In the second torque demand range (engine economic zone), the system maintains parallel drive mode to optimize fuel efficiency. The control strategy is locally optimized for each zone: first range uses series mode, second range uses parallel mode for efficiency, third range uses parallel mode with engine assistance. This localized control approach maintains fuel efficiency while reducing unnecessary mode transitions.
Solution Approach 2:
The patent uses preliminary action by predicting future torque demand based on current driving conditions and vehicle state. The control unit determines whether to maintain or switch modes in advance by evaluating predicted torque demand against the predefined torque ranges, preventing reactive switching that would occur with simple threshold-based control. This predictive approach stabilizes mode selection and reduces switching frequency.
Data Source
AI summary
A method and a device for driving a hybrid electric vehicle, and a vehicle is provided. The method includes: driving, if the vehicle demand torque is greater than a minimum value of the engine economic zone and less than a maximum value of the power assistance reserve zone, the hybrid electric vehicle in a parallel drive mode; or maintaining, if the vehicle demand torque continues to increase to the maximum value of the power assistance reserve zone, the hybrid electric vehicle being driven in the parallel drive mode when the hybrid electric vehicle is in the parallel drive mode and a torque provided by the parallel drive mode under a current drive mode is greater than a maximum torque provided by the drive motor.