On-Board Charger Surge Isolation for Inverter Short-Circuit Prevention
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Solution Overview
Problem
On-board chargers for new energy vehicles face failures due to surge impacts, particularly from lightning and system switching operations, which can cause short-circuit faults when the inverter function is enabled, especially when connected to capacitive loads, leading to risks for electronic devices.
Innovation Solution
A converter system comprising a power factor correction circuit, a surge protection circuit, and a switch circuit that converts alternating current to direct current and vice versa, while preventing a short-circuit path by controlling the switch circuit to avoid surge impact energy from forming a closed loop between the surge protection and power factor correction circuits during inverter operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an SPD including diodes is used to protect against surge impacts, then surge protection function is provided, but when inverter function is enabled and capacitive load is connected, a short-circuit path is formed through the OBC
Solution Approach 1:
The patent divides the surge protection circuit into multiple independent parallel channels, each with its own diode and switching device. This segmentation allows selective activation of protection paths based on operating conditions, preventing the formation of short-circuit paths during inverter operation while maintaining surge protection capability during charging operation.
Solution Approach 2:
The patent employs dynamically controllable switching devices (such as MOSFETs or IGBTs) in parallel with the protection diodes. These switching devices are controlled based on the operating mode (charging or inverting) to dynamically enable or disable specific current paths, thereby avoiding short-circuit faults during inverter operation while maintaining protection during charging operation.
2Object-affected harmful factors
If surge protection circuit with diodes is configured, then overvoltage and overcurrent are limited, but energy from capacitive load forms a short-circuit path during discharging cycle
Solution Approach 1:
The patent introduces controllable switching devices as intermediaries between the surge protection diodes and the power circuit. These switching devices act as mediators that can block or enable current flow through the protection diodes based on operating conditions, preventing energy from forming short-circuit paths during inverter operation while allowing surge protection during charging operation.
Solution Approach 2:
The patent changes the electrical parameters (conductivity state) of the protection circuit elements dynamically based on operating mode. By controlling the switching devices, the circuit transitions between high-conductivity state (enabling surge protection during charging) and low-conductivity state (blocking short-circuit paths during inverting), thus adapting the circuit behavior to different operational requirements.
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 inhibits surge impact energy from affecting the converter, preventing short-circuit faults and ensuring normal operation by isolating the surge protection and power factor correction circuits during inverter functions, thus enhancing the reliability and safety of on-board charging systems.
Implementation Method 1
convert a first component of a first alternating current received by an alternating current terminal of the PFC circuit into a first direct current
Implementation Method 2
the switch circuit is configured to be turned on when the direct current terminal of the PFC circuit outputs the first direct current, and to be turned off when the alternating current terminal of the PFC circuit outputs the second alternating current
Implementation Method 3
A main function of the SPD is to inhabit an overvoltage and an overcurrent that are on a circuit and that are caused by a surge impact, and limit a voltage and a current of the circuit to a low level
Data Source
AI summary
A converter for avoiding a short-circuit fault of the converter while inhibiting a surge impact includes: a power factor correction (PFC) circuit, a surge protection circuit, and a switch circuit. The PFC circuit is configured to: convert a first component of a first alternating current received by an alternating current terminal of the PFC circuit into a first direct current, and output the first direct current through a direct current terminal of the PFC circuit; and convert a second direct current received by the direct current terminal of the PFC circuit into a second alternating current, and output the second alternating current through the alternating current terminal of the PFC circuit.