Synchronous Converter Reverse Current Protection
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Solution Overview
Problem
Synchronous converters face issues with reverse current flow from the output to the input, leading to undesirable voltage spikes and potential damage, which existing reverse current protection diodes cannot prevent effectively, especially during pre-charged conditions.
Innovation Solution
A synchronous converter design that includes a reverse current protection diode and a controller to disable the high side switch during a pre-regulation interval, allowing the converter to operate in asynchronous mode and prevent reverse current flow, transitioning to synchronous mode once the output is within regulation, thereby preventing reverse current flow and achieving efficiency benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse current protection diode is used to protect the power supply, then the power supply is protected from reverse connection damage, but reverse current flow from output to input cannot be prevented causing voltage spikes
Solution Approach 1:
The patent applies dynamic switching control by transitioning the high side switch between enabled and disabled states based on the converter's operational phase. During the pre-regulation interval, the high side switch is disabled to block reverse current flow, while during normal regulation it is enabled for efficient synchronous operation. This dynamic state change resolves the contradiction by adapting the circuit configuration to different operational conditions.
Solution Approach 2:
The patent implements preliminary action by disabling the high side switch during the pre-regulation interval before normal operation begins. This pre-configured protective state prevents reverse current flow from occurring in the first place, rather than reacting to it. The controller proactively manages the switch state based on predicted operational needs, eliminating the harmful effect before it can manifest.
2Loss of energy
If synchronous operation is used to achieve higher efficiency, then converter efficiency is improved, but reverse current flow causes voltage spikes that can damage components
Solution Approach 1:
The patent dynamically adjusts the operational mode based on the converter's state. During the pre-regulation interval, it operates in asynchronous mode with the high side switch disabled to prevent voltage spikes. Once regulation is achieved, it transitions to synchronous mode with the high side switch enabled to maximize efficiency. This dynamic mode switching resolves the contradiction by optimizing for safety during vulnerable phases and for efficiency during stable operation.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively disabling the high side switch during the pre-regulation interval when reverse current flow is most likely to occur. This preventive measure counteracts the potential harmful effect before it can develop. The controller anticipates the risk of voltage spikes and takes protective action in advance, allowing safe transition to efficient synchronous operation once the risk has passed.
3Stability of the object's composition
If a large input capacitor is used to minimize charge transfer effects, then voltage stability is improved, but cost and space requirements increase
Solution Approach 1:
The patent extracts the reverse current blocking function from the input capacitor and assigns it to the high side switch. Instead of relying on the capacitor's inherent properties (which would require it to be large), the control circuitry takes over the protective function through selective switching. This separates the voltage stabilization function of the capacitor from the reverse current protection function, allowing the capacitor to remain small while protection is provided by the controlled switch.
Solution Approach 2:
The high side switch acts as an intermediary element between the input capacitor and the rest of the converter circuit. It mediates the reverse current flow by blocking it during the pre-regulation interval while allowing normal current flow during regulation. This intermediary switch provides the protective function without requiring the input capacitor to be oversized, thus resolving the contradiction between voltage stability and device 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 solution effectively prevents reverse current flow during pre-charged conditions, reducing voltage spikes and ensuring efficient synchronous operation without the need for large input capacitors, thus enhancing converter performance and reliability.
Implementation Method 1
a reverse current protection diode having an anode coupled to the input voltage and a cathode
Implementation Method 2
a high side transistor coupled to the energy storage element and responsive to a high side control signal, and a low side transistor coupled to the energy storage element and responsive to a low side control signal
Implementation Method 3
A controller is configured to generate the high side control signal and the low side control signal, wherein the low side transistor is enabled and the high side transistor is disabled during a pre-regulation interval
Data Source
AI summary
A converter to convert an input voltage into a regulated output current for supplying a load includes a reverse current protection diode having an anode coupled to the input voltage and a cathode, an energy storage element coupled to the cathode of the reverse current protection diode, a high side transistor coupled to the energy storage element and responsive to a high side control signal, and a low side transistor coupled to the energy storage element and responsive to a low side control signal. A controller is configured to generate the high side control signal and the low side control signal such that the low side transistor is enabled and the high side transistor is disabled during a pre-regulation interval.