Electric Work Vehicle Regenerative Charging Without Portable Chargers

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Solution Overview

Problem

Electric work vehicles face challenges in charging their batteries, especially when the working area is distant from charging facilities, as traditional portable chargers are expensive and inconvenient.

Innovation Solution

An electric work vehicle equipped with a motor generator and a power transfer device that allows regenerative power generation from a drive source connected to the power output shaft, enabling battery charging at any location using an inexpensive configuration, with a controller managing regenerative torque and voltage to prevent overcharging and overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a portable charger is prepared to charge the battery in the working area, then the battery can be charged at any location, but the cost becomes expensive

Engineering Contradiction:
Improvecharging location flexibilityVSAvoidcharging cost
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The motor generator serves dual purposes: it acts as a motor to drive the vehicle and as a generator to charge the battery. When the vehicle is moved by an external force (another vehicle, conveyor, etc.), the motor generator automatically generates electricity to charge the battery, eliminating the need for external charging equipment.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The motor generator is designed to perform multiple functions: it operates as a motor during vehicle operation and as a generator during regenerative charging. This multi-functionality eliminates the need for separate portable chargers, reducing costs while maintaining charging flexibility.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Productivity

If regenerative torque is increased sharply to charge the battery faster, then charging efficiency improves, but the drive source may stall or driving speed may sharply decrease

Engineering Contradiction:
Improvecharging speedVSAvoiddrive source stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The controller dynamically adjusts the regenerative torque based on the rotational speed of the motor generator. As the motor generator rotates faster, the controller increases the regenerative torque, and vice versa. This dynamic adjustment ensures efficient charging while preventing drive source stalling or sharp speed decreases.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The controller continuously monitors the rotational speed of the motor generator and adjusts the regenerative torque accordingly. This feedback mechanism ensures that the regenerative torque remains within optimal ranges, balancing charging efficiency with drive source stability and preventing stalling.

Inventive Principle:
Principle #23Feedback

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

Enables battery charging at any location without the need for expensive portable chargers, ensuring efficient and safe charging by gradually increasing regenerative torque and monitoring voltage and temperature to prevent sudden loads and overcharging.

Implementation Method 1

the controller causes the motor generator to generate regenerative power while the motor generator rotates due to receiving motive power from a drive source connected to the power output shaft

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4331900A1Electric work vehicle and charging method
Publication Date: 2024.03.06 KUBOTA CORP
  • EP4331900A1 patent drawingFigure 1
  • EP4331900A1 patent drawingFigure 2
  • EP4331900A1 patent drawingFigure 3~4

AI summary

An electric work vehicle comprises: a battery (4) configured to store electric power; a motor generator (M) conductively connected to the battery (4); a power transfer device having a power output shaft (17, 18, 20) configured to transfer motive power from the motor generator (M); and a controller configured to switch between a first mode and a second mode.