Parallel Power Supply Overvoltage Protection Logic
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Solution Overview
Problem
In power systems with multiple parallel-connected switching power supplies, the absence of OR-ing circuits leads to overvoltage conditions causing all power supplies to be disabled when one faulty supply raises the common bus voltage, resulting in system failure.
Innovation Solution
A pulse-width-modulated (PWM) or pulse-frequency-modulated (PFM) driven OVP system with bus voltage overvoltage detection, modulation flag detection, and logic circuitry to differentiate between normal and faulty conditions, initiating appropriate responses such as shutdown or temporary disabling of switching power supplies to maintain bus voltage availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple switching power supplies are connected directly to a common bus without OR-ing circuits, then system cost and complexity are reduced, but overvoltage conditions cause all power supplies to be disabled resulting in system failure
Solution Approach 1:
The patent introduces an intermediary OVP circuit between the power supply and the common bus. This OVP circuit acts as a mediator that monitors bus voltage and selectively connects or disconnects the power supply from the bus using switching elements, preventing faulty power supplies from causing system-wide failure while maintaining direct bus connection architecture
Solution Approach 2:
The OVP circuit implements feedback by continuously monitoring the common bus voltage and using this information to control the switching elements. When overvoltage is detected, the feedback signal triggers the switching element to disconnect the faulty power supply, creating a closed-loop protection mechanism that maintains system reliability
2Reliability
If OVP circuits are added to protect against overvoltage, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the protection function into a separate, dedicated OVP circuit that is integrated with each power supply. This extraction allows the main power supply circuitry to remain simple while the specialized OVP handling is isolated in a compact module with minimal additional components
Solution Approach 2:
The OVP circuit performs multiple functions: it monitors bus voltage, detects overvoltage conditions, controls switching elements to isolate faulty power supplies, and prevents system-wide failure. This multi-functionality consolidates several protection and control functions into a single integrated circuit, reducing overall system complexity
Data Source
AI summary
An OVP system which includes a plurality of OVP circuits coupled to respective parallel-connected switching power supplies. Each OVP circuit comprises a bus voltage overvoltage detection circuit having a first output which toggles when the voltage on the common power bus exceeds a reference voltage, a modulation flag detection circuit which receives a value that varies with a parameter associated with the PWM or PFM drive signals generated for the switching power supply to which the OVP circuit is coupled and has a second output which toggles when the parameter value exceeds a reference parameter value, logic circuitry which toggles an output when both the first and second outputs toggle, and an overvoltage response circuit which initiates a course of action such as latching or shutting down the switching power supply to which the OVP circuit is coupled when the logic circuitry's output toggles.