Dual DC-DC Converter Solar Control for Max Power Point Tracking
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Solution Overview
Problem
Existing solar power generation devices cannot maintain the solar battery's operating point at the maximum power point when the storage battery approaches a fully-charged state, leading to suboptimal energy conversion.
Innovation Solution
A solar power generation device comprising a first DC-DC converter, a storage battery, a second DC-DC converter, and a control unit that adjusts the duty ratios of both converters to keep the solar battery's operating point at the maximum power point even when the storage battery's state of charge is equal to or greater than a predetermined value, preventing charging and optimizing power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the duty ratio of the first DC-DC converter is changed to prevent charging the storage battery when it is fully charged, then the storage battery is protected from overcharging, but the solar battery cannot be operated at the maximum power point
Solution Approach 1:
The system divides the power conversion function into two separate DC-DC converters: the first DC-DC converter handles the solar battery to storage battery power transfer, while the second DC-DC converter handles the storage battery to load power transfer. This segmentation allows independent control of each converter's duty ratio, enabling the control unit to prevent overcharging of the storage battery through the first converter while simultaneously maintaining the solar battery at its maximum power point through the second converter.
Solution Approach 2:
The control unit dynamically changes the duty ratio parameters of both DC-DC converters based on the storage battery's charge state. When the storage battery is fully charged, the control unit adjusts the duty ratio of the first DC-DC converter to zero (or a minimal value) to prevent charging, while simultaneously adjusting the duty ratio of the second DC-DC converter to maintain the solar battery operating point at the maximum power point, thus optimizing power extraction without overcharging the storage battery.
2Reliability
If the operating point of the solar battery is shifted from the maximum power point to an open-circuit voltage side when the storage battery is fully charged, then the storage battery is protected from overcharging, but the energy conversion efficiency is reduced
Solution Approach 1:
By segmenting the power conversion system into two independent DC-DC converter stages, the invention allows the first converter to be controlled for battery protection purposes while the second converter maintains optimal power extraction from the solar battery. This segmentation eliminates the need to shift the solar battery operating point away from the maximum power point, thereby preventing energy loss.
Solution Approach 2:
The second DC-DC converter acts as an intermediary between the solar battery and the storage battery system. It enables the control unit to decouple the control objectives: protecting the storage battery from overcharging while maintaining the solar battery at its maximum power point. The intermediary converter allows power to be drawn from the solar battery at optimal efficiency without directly charging the fully charged storage battery.
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 continuous operation of the solar battery at the maximum power point, ensuring efficient energy conversion and preventing overcharging of the storage battery, thereby maximizing energy generation and extending battery lifespan.
Implementation Method 1
a first DC-DC converter to which an output of a solar battery is input
Implementation Method 2
a second DC-DC converter that converts a voltage of the storage battery
Implementation Method 3
solar battery
Data Source
AI summary
A solar power generation device is provided which includes a first DC-DC converter to which an output of a solar battery is input, a storage battery to which an output of the first DC-DC converter is input, a second DC-DC converter that converts a voltage of the storage battery, and a control unit. The control unit changes a duty ratio of the first DC-DC converter so as not to charge the storage battery and changes a duty ratio of the second DC-DC converter so as to set an operating point of the solar battery to a maximum power point, when a value indicating a state of charge of the storage battery is equal to or greater than a predetermined value.