Charging Pile Pre-Charging Circuit for Overload Current Protection
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Solution Overview
Problem
The existing flyback topology structure in power conversion circuits is inadequate in handling extreme operating conditions such as short circuits and high-power overloads, leading to potential failure of the switching transistor due to excessive current and temperature.
Innovation Solution
A charging apparatus and charging pile are designed with a pre-charging circuit that includes a primary-side and secondary-side circuit, where a current sampling resistor in the secondary-side circuit detects excessive currents and triggers a controller to adjust the duty cycle of the switching transistor, thereby preventing overheating and failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CBC function is triggered to protect the switching transistor during overload, then the switching transistor is protected from immediate damage, but the charging speed is reduced due to repeated triggering
Solution Approach 1:
The patent implements preliminary protection actions by detecting overload conditions before they cause damage to the switching transistor. The controller monitors the current through the switching transistor and proactively reduces the duty cycle when overload is detected, preventing the need for repeated CBC triggering and maintaining charging speed while ensuring transistor protection.
2Productivity
If the pre-charging circuit is designed for high charging speed, then the charging efficiency is improved, but the circuit becomes vulnerable to damage under extreme operating conditions
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the current flowing through the switching transistor in the pre-charging circuit. When the current exceeds a predetermined threshold indicating extreme operating conditions, the controller provides feedback to reduce the duty cycle of the switching transistor, thereby limiting the current and protecting the circuit while maintaining high charging speed under normal conditions.
3Productivity
If the duty cycle of the switching transistor is increased to improve charging speed, then the charging efficiency is improved, but the switching transistor is prone to failure due to excessively large current
Solution Approach 1:
The patent employs dynamic control of the switching transistor's duty cycle based on real-time current conditions. The controller dynamically adjusts the duty cycle - increasing it to improve charging speed when current is within safe limits, and reducing it when current exceeds thresholds to prevent transistor failure. This dynamic adjustment allows the system to optimize charging speed while maintaining switching transistor durability throughout operation.
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
The solution effectively reduces the duty cycle of the switching transistor during short circuits or overloads, preventing excessive current flow and subsequent overheating, thus protecting the transistor and preventing damage to the charging apparatus.
Implementation Method 1
a current sampling resistor in the secondary-side circuit detects excessive currents
Implementation Method 2
a pre-charging circuit that includes a primary-side and secondary-side circuit, where a current sampling resistor in the secondary-side circuit detects excessive currents and triggers a controller to adjust the duty cycle of the switching transistor
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
This application provides a charging apparatus and a charging pile. The charging apparatus includes a direct current bus, an AC/DC conversion circuit, a DC/DC conversion circuit, and a pre-charging circuit. The AC/DC conversion circuit and the DC/DC conversion circuit are connected through the direct current bus, and the pre-charging circuit is configured to charge the direct current bus before the AC/DC conversion circuit is turned on. The pre-charging circuit includes a primary-side circuit and a secondary-side circuit, the secondary-side circuit includes a current sampling resistor, and the current sampling resistor is configured to sample a current of the secondary-side circuit. The current sampling resistor in the secondary-side circuit is used to detect a current of the secondary-side circuit in the pre-charging circuit. After a short circuit or overload occurs, a duty cycle of a switching transistor in the pre-charging circuit may be controlled based on a sampled current of the secondary-side circuit, to avoid a problem that the switching transistor fails due to over-temperature caused by an excessively large current flowing through the switching transistor.