PV Controller Startup Circuit for Battery-Free Low-Irradiance Operation
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Solution Overview
Problem
Photovoltaic systems with batteries are limited by the battery's service life, and the start-and-stop phenomenon during low irradiance conditions can damage the system components.
Innovation Solution
A control circuit for a photovoltaic system that includes an input, output, power dissipation circuit, voltage regulation circuit, and a comparator, with controllable switches to manage the connection to the photovoltaic module and controller, ensuring proper start-up based on voltage and current thresholds without a battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a battery is used in the photovoltaic system, then the system can store energy and provide voltage during low irradiance, but the battery service life limits the overall system lifetime
Solution Approach 1:
The patent removes the battery from the photovoltaic system entirely, extracting the energy storage component that was limiting system lifetime. The control circuit replaces the battery's voltage regulation function by dissipating excess power through a controlled resistor and regulating voltage using a Zener diode and comparator circuit, thereby eliminating the battery service life constraint while maintaining continuous operation.
2Duration of action of stationary object
If the system operates without a battery, then the system lifetime is extended, but start-and-stop phenomena occur during low irradiance conditions
Solution Approach 1:
The control circuit performs preliminary action by monitoring the photovoltaic module voltage and current before the controller starts operating. When voltage exceeds the Zener diode breakdown voltage and current reaches threshold levels, the circuit proactively prepares the controller for startup by switching the second switch to connect the controller input, preventing unstable operation during low irradiance conditions.
Solution Approach 2:
The comparator continuously compares the photovoltaic module voltage (through the voltage divider) with the reference voltage from the Zener diode, providing feedback control. When the module voltage exceeds the threshold, the comparator output changes state, triggering the switches to connect or disconnect the controller, thereby maintaining reliable operation by responding to real-time electrical conditions.
3Measurement precision
If the controller starts when voltage is high but current is insufficient, then voltage threshold is met, but the start attempt fails and causes start-and-stop phenomena
Solution Approach 1:
The control circuit acts as an intermediary between the photovoltaic module and the controller, mediating the startup conditions. It uses the voltage divider and Zener diode to create a reference voltage threshold, and the comparator to precisely detect when both voltage and current conditions are satisfied, ensuring the controller only starts when truly ready, thus preventing failed startup attempts.
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 the photovoltaic system to operate without a battery, improving its service life by preventing start-and-stop phenomena and ensuring reliable controller operation.
Implementation Method 1
a photovoltaic module that is suitable for converting energy from photons generated by the sun into electrical energy
Implementation Method 2
The Zener diode has a Zener voltage, the comparator being supplied with a supply voltage equal to twice the Zener voltage
Data Source
AI summary
A control circuit of a controller of a photovoltaic system is provided, the control circuit including an input, an output, a start unit consisting of a power dissipation circuit, a voltage regulation circuit and a comparator, a first switch having a position wherein the start unit is connected to the input and an inverse position, and a second switch having a position wherein the input and the output are not connected and an inverse position. The comparator compares the voltages of the dissipation circuit and of the regulation circuit, the comparator outputting a command voltage of the two switches on the basis of the comparison.