Totem Pole PFC Surge Protection Using Bypass-Diode Current Sensing
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Solution Overview
Problem
Conventional surge protection circuits fail to provide suitable and reliable protection for totem pole PFCs, particularly those with polarity changers, against surge voltages and power line disturbances.
Innovation Solution
A totem pole PFC with a surge protection circuit comprising bypass-diode branches, switch branches, polarity changer branches, and current sensors that detect current flow through bypass-diodes to quickly and reliably protect the PFC by switching off switches when a surge voltage is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional surge protection circuits are used, then general surge protection is provided, but they fail to provide suitable and reliable protection for totem pole PFC with polarity changers
Solution Approach 1:
The surge protection circuit is specifically adapted for the totem pole PFC topology by implementing detection of surge currents flowing through bypass diodes in the polarity changer branch. This localized approach targets the specific vulnerability points in the totem pole PFC architecture, providing reliable protection tailored to this converter type rather than using generic surge protection circuits.
Solution Approach 2:
The control unit proactively monitors bypass diode currents and detects surge conditions before they can cause damage to the PFC circuit. By continuously monitoring the current through bypass diodes and comparing it against threshold values, the system takes preliminary protective action by switching off relevant switches when surge conditions are detected, preventing breakdown rather than responding after damage occurs.
2Measurement precision
If bypass-diode branches are added for surge detection, then surge detection capability is improved, but device complexity increases
Solution Approach 1:
The bypass diodes already present in the totem pole PFC polarity changer circuitry are utilized for surge detection purposes. The control unit monitors the current flowing through these existing bypass diodes, which naturally conduct during normal operation and also during surge conditions. This approach leverages existing circuit elements to provide surge detection functionality without requiring entirely separate detection circuits, thereby improving measurement precision while minimizing additional complexity.
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 surge protection circuit effectively detects and responds to surge voltages and power line disturbances, preventing breakdowns by switching off switches and ensuring the PFC operates safely and reliably.
Implementation Method 1
the at least one current sensor is a current transformer, a Hall-effect sensor
Data Source
AI summary
The disclosure concerns a totem pole PFC with a surge protection circuit, wherein the totem pole PFC comprises at least one bypass-diode branch with at least two bypass-diodes, at least one switch branch with at least two switches, at least one polarity changer branch with at least two switches, an input bridge connecting the switch branch(es) with an input voltage source, and at least one bypass branch connecting the input bridge in parallel with the bypass-diodes of the bypass-diode branch(es). The surge protection circuit comprises at least one current sensor configured to detect a current flowing through at least one of the bypass-diodes of the bypass-diode branch(es), and a control unit configured to receive a detected current value from the current sensor(s) and to switch at least one switch of the totem pole PFC at least in dependence on the detected current value.