Schottky Diode Bypass Circuit for Power Factor Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Schottky diodes face issues with high peak currents leading to current saturation and increased dissipation, which can result in device failure, especially at high temperatures and high currents.
Innovation Solution
A diode circuit comprising a Schottky diode with a parallel bypass branch containing a switch and a bypass diode in series, where the switch operation is dependent on the voltage across the Schottky diode, allowing the bypass diode to activate only at high currents, thereby reducing excessive forward voltage and providing bypass current protection without external control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a Schottky diode is used for rectification in PFC circuits, then fast switching and low forward voltage drop are achieved, but current saturation and excessive power dissipation occur at high peak currents
Solution Approach 1:
The diode function is segmented into two parallel paths: a Schottky diode for normal operation and a bypass diode for high current conditions. This segmentation allows each diode type to operate in its optimal range, with the Schottky handling fast switching at low currents and the bypass diode handling high peak currents, thereby resolving the contradiction between fast switching and low power dissipation.
Solution Approach 2:
The invention changes the operational parameters by introducing a voltage-dependent switch that activates the bypass diode when the Schottky diode voltage exceeds a threshold. This parameter-based control allows the system to transition from Schottky diode conduction to bypass diode conduction based on voltage/current conditions, optimizing both switching speed and power dissipation characteristics.
2Reliability
If the bypass diode is always active in parallel with the Schottky diode, then current saturation is prevented, but the bypass diode conducts during normal operation causing unnecessary power loss
Solution Approach 1:
The bypass diode's activation is made dynamic through the voltage-dependent switch rather than being statically always-on. The switch responds to real-time voltage conditions across the Schottky diode, enabling the bypass diode only when high current conditions are detected. This dynamic control prevents unnecessary conduction during normal operation while ensuring protection when needed.
Solution Approach 2:
The voltage-dependent switch provides feedback control by monitoring the voltage across the Schottky diode and using this information to control the bypass diode's activation. When the Schottky diode voltage exceeds a threshold (indicating high current stress), the switch activates the bypass diode. This feedback mechanism ensures the bypass diode operates only when necessary, preventing energy loss during normal operation while maintaining reliability.
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 limits the forward voltage at high currents, preventing device failure and maintaining efficiency in power factor correction circuits by using a voltage-dependent switch to activate the bypass diode only when necessary, thus reducing power dissipation and extending the lifespan of the Schottky diode.
Implementation Method 1
Schottky diodes face issues with high peak currents leading to current saturation and increased dissipation
Implementation Method 2
A diode circuit comprising a Schottky diode with a parallel bypass branch containing a switch and a bypass diode in series, where the switch operation is dependent on the voltage across the Schottky diode
Implementation Method 3
When the switch S1 is closed, a current is developed in the inductor which increases according to the time constant of the circuit, this is termed the storage phase. The switch is then opened after a small period of time and this causes the voltage across the switch to increase as the inductor's collapsing magnetic field attempts to maintain the current.
Implementation Method 4
The inductor and capacitor can form a resonant circuit. Due to the resonant circuit, the output voltage under these circumstances can become much higher than the applied input voltage.
Data Source
AI summary
Embodiments relate to a diode circuit which uses a Schottky diode. A parallel bypass branch has a switch and bypass diode in series. The operation of the switch is dependent on the voltage across the Schottky diode so that the bypass function is only effective when a desired voltage is reached. The diode circuit can be used as a replacement for a single diode, and provides bypass current protection preferably without requiring any external control input.