Electric Drive System Control for Dump Trucks
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Solution Overview
Problem
Conventional drive systems for electrically driven dump trucks cannot achieve engine driving characteristics suitable for both hydraulic system operation during non-traveling and electric motor operation during traveling, as they use a single target revolution speed characteristic for both applications, leading to suboptimal performance in terms of stability, flow, and acceleration.
Innovation Solution
A drive system with a prime mover, electronic governor, alternating-current generator, hydraulic pump, and electric motors, where two sets of target revolution speed characteristics are used based on the shift lever position to control the prime mover, one for hydraulic pump operation and another for electric motor operation, allowing separate calculation and control of target revolution speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single target revolution speed characteristic is used for both hydraulic pump operation and electric motor operation, then the control system is simple, but the driving characteristics are suboptimal for both applications
Solution Approach 1:
The patent segments the target revolution speed characteristic into two distinct sets: one for hydraulic pump operation and another for electric motor operation. The control unit selects the appropriate set based on the operational mode, thereby optimizing performance for each specific application while maintaining manageable system complexity through structured division.
Solution Approach 2:
The patent implements dynamic selection of target revolution speed characteristics based on the shift lever position. The control unit dynamically switches between different characteristic sets according to operational requirements, allowing the system to adapt its behavior to match the specific demands of hydraulic pump operation or electric motor operation.
2Adaptability or versatility
If the prime mover is driven over a wide revolution speed range for hydraulic pump operation, then the working speed can be adjusted over a wide range, but the acceleration performance during traveling is reduced
Solution Approach 1:
The patent segments the revolution speed range requirements into two distinct operational modes. For hydraulic pump operation, the system allows wide revolution speed range adjustment to achieve maximum flow and working speed variability. For electric motor operation, the system uses a different target characteristic optimized for acceleration, thereby resolving the conflict between wide-range adaptability and acceleration performance through operational segmentation.
Solution Approach 2:
The control unit dynamically adjusts the target revolution speed characteristics based on the shift lever position. When in hydraulic operation mode, the system permits wide speed range adjustment for versatility. When in traveling mode, the system switches to characteristics optimized for acceleration, thereby dynamically adapting the speed range to match the current operational priority.
3Speed
If the prime mover is driven starting from medium speed for electric motor operation, then the acceleration is excellent, but the stability and flow adjustment range for hydraulic pump operation is reduced
Solution Approach 1:
The patent segments the operational requirements into distinct target revolution speed characteristics for different modes. The first set optimizes for stability and wide flow adjustment range during hydraulic pump operation, while the second set optimizes for acceleration performance during electric motor operation. This segmentation allows each mode to operate with its ideal characteristics without compromising the other.
Solution Approach 2:
The control unit dynamically selects the appropriate target revolution speed characteristic set based on the shift lever position. During hydraulic pump operation, the system dynamically maintains stable operation with wide adjustment range. During traveling mode, the system dynamically switches to characteristics that provide excellent acceleration, thereby dynamically balancing stability and acceleration based on operational context.
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 enables stable operation of the prime mover over a wide range for hydraulic pump operation and improved responsiveness and acceleration during electric motor operation, enhancing working speed adjustment and fuel efficiency.
Implementation Method 1
an alternating-current generator that is driven by the prime mover
Implementation Method 2
two electric motors, each of which is driven by the electric power supplied by the alternating-current generator
Data Source
AI summary
Engine driving characteristics are achieved for driving a hydraulic system during non-traveling and traveling in an electrically driven dump truck.When a shift lever 16 is located at a neutral position, the target revolution speed Nr1 corresponding to the operation amount (p) of an accelerator pedal 1 is calculated on the basis of first target revolution speed characteristics (Nr1(p)) which are suitable for driving of a hydraulic pump for working so that an electronic governor 4a is controlled on the basis of this target revolution speed. When the shift lever 16 is located at a forward position, the target revolution speed Nr2 corresponding to the operation amount of the accelerator pedal 1 is calculated on the basis of second target revolution speed characteristics (Nr2(p)) which are suitable for driving of electric motors 12R, 12L so that the electronic governor 4a is controlled on the basis of this target revolution speed.