Hybrid Vehicle Control Device Engine Speed Stability

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Solution Overview

Problem

In hybrid vehicles, when a vehicle undergoes downhill movement, the existing control methods can lead to uncomfortable driving experiences due to unintended engine rotational speed increases and limited regenerative torque, causing the vehicle to accelerate uncontrollably.

Innovation Solution

A control method that limits the power generation of the first rotating electrical machine when the input limit value is below a threshold, ensuring the second rotating electrical machine generates sufficient torque without relying on the first machine, thereby maintaining vehicle control and preventing uncomfortable acceleration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the first rotating electrical machine is controlled to generate torque to suppress engine rotational speed overshoot, then the engine rotational speed can be stabilized, but the power generation amount of the first machine increases and limits the regenerative torque of the second machine, causing vehicle downhill movement to increase

Engineering Contradiction:

Improveengine rotational speed stabilityVSAvoidvehicle downhill movement speed

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The control device applies different control strategies to the first and second rotating electrical machines based on their respective functions. The first machine's power generation is suppressed locally to prioritize the second machine's regenerative torque for downhill movement control, while the engine rotational speed is stabilized through other means such as fuel injection control or engine braking.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The control device segments the functions of the two rotating electrical machines: the first machine handles engine start and auxiliary functions, while the second machine is dedicated to vehicle propulsion and downhill movement control. This segmentation allows the second machine to provide sufficient regenerative torque without being limited by the first machine's power generation.

Inventive Principle:

Principle #1Segmentation

2Speed

If the first rotating electrical machine is motored to increase engine rotational speed quickly, then the power consumption of the first motor increases and engine speed can be raised, but the driver feels discomfort due to unintended engine rotational speed changes

Engineering Contradiction:

Improveengine rotational speedVSAvoiddriver comfort

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The control device applies preliminary anti-action by suppressing the power generation of the first rotating electrical machine before it can significantly affect engine rotational speed. This prevents the unintended engine speed increases that would cause driver discomfort, while still allowing the second machine to provide necessary regenerative torque for downhill movement control.

Inventive Principle:

Principle #9Preliminary anti-action

3Power

If the input limit value of the power storage device is lowered, then the power generation of the second rotating electrical machine is limited by the first machine's power generation amount, but the regenerative torque of the second machine is limited, causing vehicle downhill movement to increase

Engineering Contradiction:

Improveinput power to power storage deviceVSAvoidregenerative torque of second machine

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The control device applies local quality by differentiating the power management strategy for the two rotating electrical machines. The first machine's power generation is suppressed to maintain a lower input limit for the power storage device, while the second machine is allowed to generate sufficient regenerative torque for downhill movement control, prioritizing vehicle safety over maximum energy recovery.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively suppresses vehicle downhill movement without causing discomfort to the driver by securing the regenerative torque of the second machine and preventing excessive engine rotational speed changes, thus enhancing driving controllability.

Implementation Method 1

a first rotating electrical machine, a planetary gear mechanism in which the internal combustion engine, the first rotating electrical machine, and an output shaft are connected, a second rotating electrical machine connected to the output shaft

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a power storage device capable of storing electric power generated by the first rotating electrical machine and electric power generated by the second rotating electrical machine

Methodology Applied

Scientific EffectElectrochemical energy storage: Battery (electricity)

Data Source

PatentUS11529945B2Hybrid vehicle and control method thereof

Publication Date: 2022.12.20 TOYOTA JIDOSHA KK

AI summary

The control device controls the first MG and the second MG so that the input power to the power storage device does not exceed the input limit Win. Further, the control device controls the first MG and the engine so that the rotational speed of the engine approaches the target when the engine is operating under load, when the input limit Win is lowered in a situation where the second MG moves backward while generating torque in the forward direction, and the engine is operating under load, the control device suppresses the amount of power generated by the first MG.