Work Vehicle Regenerative Charging Control
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Solution Overview
Problem
Existing work vehicles face challenges in stably supplying regenerative power from an electric motor to a battery and accurately estimating the time required for charging, as the regenerative power varies with the rotation speed of the electric motor.
Innovation Solution
A controller is implemented to perform regeneration control at a constant current value, ensuring the battery is charged with regenerative power at a stable rate regardless of the electric motor's rotation speed, allowing for efficient charging even when the vehicle is in forward or reverse drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative power of the electric motor is supplied to the battery without constant current control, then the charging process is simple, but the supply of regenerative power varies with rotation speed making it difficult to stably charge the battery and estimate charging time
Solution Approach 1:
The controller changes the operating parameter of the electric motor from speed-proportional power to constant current mode during regenerative braking. By controlling the electric motor to output regenerative power at a constant current value regardless of rotation speed, the system achieves stable battery charging. This parameter change resolves the contradiction by maintaining reliability through constant current control while managing complexity through electronic control algorithms.
2Measurement precision
If regenerative power is supplied at variable current based on rotation speed, then the control system is simple, but the charging time cannot be easily estimated and power supply is unstable
Solution Approach 1:
The system changes the current control parameter from variable (speed-dependent) to constant during regenerative charging. The controller maintains a constant current value regardless of rotation speed variations, which enables precise charging time estimation. This parameter change improves measurement precision by providing a predictable, constant charging rate that can be easily timed and monitored.
3Speed
If the electric motor operates at low rotation speed for regenerative charging, then the vehicle can maintain low speed operation, but the charging current is low extending charging time
Solution Approach 1:
The system changes the control parameter from speed-proportional power output to constant current output. This allows the electric motor to operate at low rotation speeds while maintaining a high, constant charging current. The parameter change resolves the contradiction by decoupling current magnitude from rotation speed, enabling effective regenerative charging even at low speeds where traditional speed-proportional control would produce insufficient charging current.
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 stabilizes the supply of regenerative power and allows for accurate estimation of charging time, reducing the time required to charge the battery and ensuring consistent performance across varying rotation speeds.
Implementation Method 1
an electric motor configured to drive the other of the pair of front wheels and the pair of rear wheels... The electric motor also acts as a power generator for charging the battery with regenerative power of the electric motor
Data Source
AI summary
A work vehicle includes a propelling device, which consists of a pair of right and left front wheels and a pair of right and left rear wheels, an engine configured to drive one of the pair of front wheels and the pair of rear wheels, an electric motor configured to drive the other of the pair of front wheels and the pair of rear wheels, a battery configured to supply electric power to the electric motor, and a controller configured to control the electric motor. The controller performs regeneration control at constant current value to charge the battery with regenerative power of the electric motor at a constant current value regardless of rotation speed of the electric motor.