Hybrid Vehicle Motor Control for Smooth Acceleration
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Solution Overview
Problem
In hybrid vehicles, there is a time lag between the accelerator being stepped on and the engine firing up, leading to a stagnation in drive force and discomfort for the driver due to the inability to achieve smooth acceleration.
Innovation Solution
A vehicle control method that limits the initial drive force output by a second electric motor using battery power and gradually increases it over time until the internal combustion engine is fired up, ensuring smooth and continuous acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the drive force is limited to the maximum electric power available from the battery, then the battery capacity is fully utilized, but the drive force stagnates during engine startup and smooth acceleration feeling cannot be achieved
Solution Approach 1:
The patent applies dynamics by making the drive force output dynamic rather than static. The second electric motor's output is continuously adjusted over time during the engine startup period, transitioning from an initial limited value to a final value that utilizes the battery's full capacity. This dynamic adjustment ensures smooth acceleration feeling while fully utilizing battery power, resolving the contradiction between power utilization and acceleration smoothness.
Solution Approach 2:
The patent applies preliminary action by preparing the drive force increase schedule in advance before engine startup. The control device calculates the initial drive force value, final drive force value, and time required for engine startup beforehand, then smoothly increases the drive force according to this pre-planned schedule during the startup period. This prevents drive force stagnation and ensures smooth acceleration from the beginning of the startup process.
2Speed
If the drive force increases rapidly to meet accelerator input, then the driver's acceleration demand is met, but the engine cannot be fired up and power generation cannot start in time
Solution Approach 1:
The patent applies preliminary action by calculating the time required for engine startup and power generation before the engine actually starts. The control device uses this pre-calculated time information to determine the appropriate rate of drive force increase, ensuring that the drive force smoothly reaches its final value just as the engine fires up and power generation begins. This coordination ensures both rapid acceleration response and reliable engine startup.
3Power
If the battery supplies maximum power immediately, then the maximum drive force is achieved, but the drive force does not increase smoothly over time causing driver discomfort
Solution Approach 1:
The patent applies dynamics by implementing a continuous, smooth increase in drive force output over time rather than an abrupt jump to maximum power. The second electric motor's output is adjusted dynamically according to a calculated schedule that considers the engine startup time, ensuring the drive force increases smoothly from an initial value to the final maximum value. This eliminates sudden changes in acceleration that would cause driver discomfort while still achieving maximum battery power utilization.
Data Source
AI summary
In a vehicle control method, when drive force which a second electric motor is requested to output increases in a state where an internal combustion engine is stopped, drive force which the second electric motor outputs by using electric power supplied by a battery is limited to a lower level than maximum drive force determined from electric power which can be supplied by the battery to drive an electric-powered vehicle. Then, the drive force which the second electric motor outputs by using the electric power supplied by the battery is increased over time in a period from when the second electric motor outputs the drive force limited to the lower level to when the internal combustion engine is fired up and a first electric motor starts power generation.