Generator Current Control for Low-Load Converter Efficiency
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Solution Overview
Problem
Existing power conversion devices maintain a constant exciting current command value corresponding to the maximum torque of the power generator, leading to reduced efficiency when the load is low, such as during vehicle coasting.
Innovation Solution
A power conversion device with a target torque calculator and controller that adjusts torque and exciting current command values based on load conditions, ensuring a positive correlation between these values to optimize generator efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the exciting current command value is maintained at a constant value corresponding to the maximum torque of the power generator, then the maximum torque capability is ensured, but the efficiency of the power generator decreases when the load is low
Solution Approach 1:
The exciting current command value is changed from a constant value to a dynamically adjustable value that varies according to the target torque. The controller adjusts the exciting current command value based on the relationship between target torque and maximum torque, enabling the power generator to operate at optimal efficiency across different load conditions while maintaining the capability to deliver maximum torque when needed.
Solution Approach 2:
The exciting current command value is modified as a variable parameter rather than a fixed constant. The controller calculates and adjusts this parameter based on the ratio of target torque to maximum torque, allowing the power generator's operating parameters to adapt to changing load requirements and maintain high efficiency across the operating range.
2Loss of energy
If the exciting current command value is reduced to improve efficiency during low load, then the power generator efficiency increases, but the maximum torque capability is compromised
Solution Approach 1:
The system maintains dynamic adjustability of the exciting current command value, allowing it to be reduced during low-load operation to improve efficiency while being capable of increasing to the maximum value when high torque is required. This dynamic adjustment ensures both efficiency improvement and torque capability are preserved as needed.
Solution Approach 2:
The exciting current command value is treated as a controllable variable that can be adjusted within a range from reduced values (for efficiency) to maximum values (for torque capability). The controller selectively modifies this parameter based on instantaneous torque requirements, balancing efficiency and capability.
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 configuration improves the efficiency of the power generator by adjusting current command values in accordance with load changes, enhancing performance during varying operational states.
Implementation Method 1
a converter that converts alternating current (AC) power supplied from a power generator that is driven by an internal-combustion engine to generate power into direct current (DC) power, and an inverter that converts an output from the converter into AC power
Data Source
AI summary
A power conversion device includes a power converter to convert power generated by a power generator into power to be supplied to a load, a target torque calculator to calculate a target torque of the power generator in accordance with an operation state of the load, and a power conversion controller to control the power converter based on a torque current command value and an exciting current command value for causing an output torque of the power generator to approach the target torque. Absolute values of the torque current command value and the exciting current command value calculated by the power conversion controller during the power generation by the power generator have a positive correlation.