EV Controller Torque Restriction Dynamics
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Solution Overview
Problem
Existing electric vehicle controllers experience deterioration in driveability due to rapid variations in driving force caused by abrupt changes in torque command restrictions, leading to poor acceleration and high-load conditions.
Innovation Solution
Implementing a controller with a restriction control unit that limits permissible output power based on the load condition of the electric storage device and reducing the rate of increase of electric power output when returning from a restricted condition, thereby suppressing rapid output variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque command is restricted when battery voltage is low, then the storage battery can maintain its voltage level, but the vehicle acceleration performance deteriorates
Solution Approach 1:
The patent implements dynamic control of the torque command restriction by introducing a release determination unit that monitors multiple conditions (accelerator pedal operation, vehicle speed changes, brake operation) to determine when to release the restriction. This allows the system to adaptively adjust between maintaining battery voltage stability and restoring acceleration performance based on real-time driving conditions, rather than using a static restriction approach.
2Reliability
If the torque command restriction is cancelled when accelerator pedal is released, then the storage battery voltage can be recovered, but rapid torque variations occur when acceleration is requested again
Solution Approach 1:
The patent applies preliminary action by maintaining the torque command restriction in a suspended state even after the release determination conditions are met. The restriction is not immediately cancelled but is held in a state where it can be quickly re-applied if needed, while still allowing the battery voltage to recover. This prevents sudden torque variations when acceleration is requested again, as the restriction can be smoothly re-engaged rather than causing abrupt changes.
Solution Approach 2:
The patent uses preliminary anti-action by keeping the restriction determination in a state that allows for quick re-application of torque restriction before actual acceleration demand occurs. This preemptive measure prevents the harmful effect of rapid torque variations by having the control system ready to counteract potential voltage drops before they occur, rather than reacting after the problem arises.
3Speed
If the torque command restriction is immediately cancelled after release determination, then the vehicle can accelerate quickly, but the driveability deteriorates due to rapid torque variations
Solution Approach 1:
The patent implements dynamic control by introducing a sustained period after release determination before actually cancelling the torque command restriction. During this sustained period, the system monitors driving conditions and only cancels the restriction when appropriate, allowing for smooth transitions rather than abrupt changes. This maintains good driveability while still enabling timely acceleration when needed.
Data Source
AI summary
An electric vehicle includes an electric storage device, an electric motor that generates driving force for running the vehicle, using electric power output from the storage device, and a controller that controls an output of the storage device. The controller includes a restriction control unit that restricts a permissible output power indicating electric power permitted to be output from the storage device, based on a load condition of the storage device, and an output control unit that reduces the rate of increase of the electric power output from the storage device as the permissible output power is more likely to be restricted when returning from a restricted condition in which the permissible output power is restricted by the restriction control unit.