Power Converter Diode Segmentation for Loss Reduction
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Solution Overview
Problem
Existing power converting devices face inefficiencies due to conduction loss in diodes and reverse recovery loss, which are not adequately reduced by current technologies, leading to increased device size and cost, especially when using fast recovery diodes or wide bandgap materials.
Innovation Solution
A power converting device configuration that includes a series circuit of a fast recovery diode and a rectifying diode with a lower forward voltage drop and higher reverse recovery loss, connected in parallel with a second semiconductor switching device to minimize conduction and reverse recovery losses, while using a low breakdown voltage switching device to reduce on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If switching frequency is increased to reduce inductor size, then inductor size is reduced, but reverse recovery loss increases
Solution Approach 1:
The patent segments the diode functionality to allow high-frequency operation. By using a fast recovery diode specifically optimized for high-frequency switching, the system can increase switching frequency to reduce inductor size while the fast recovery diode minimizes the associated reverse recovery losses.
2Loss of energy
If wide bandgap material is used to reduce reverse recovery loss, then reverse recovery loss is reduced, but device cost increases
Solution Approach 1:
The patent uses a hybrid approach where the expensive fast recovery characteristics are achieved through a combination of diodes rather than requiring expensive wide bandgap materials for the entire system. The rectifying diode can be a standard, lower-cost component while the fast recovery diode handles the high-frequency switching 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
This configuration significantly reduces semiconductor device conduction and reverse recovery losses, enhancing overall efficiency while preventing increases in device size and cost, by utilizing the low forward voltage drop characteristic of rectifying diodes and minimizing reverse recovery.
Implementation Method 1
a reverse voltage is applied to the diode 4 when the switching device 3 is turned on, because of which a reverse current—a so-called reverse recovery current—momentarily flows
Implementation Method 2
when the switching device 3 is turned off, current flows along a path from the direct current power supply 1 through the inductor 2, diode 4, and capacitor 5
Implementation Method 3
When the switching device 3 is turned on, a voltage practically equivalent to a voltage Vin of the direct current power supply 1 is applied to both ends of the inductor 2, and current flows along a path
Implementation Method 4
when the switching device 3 is turned off, current flows along a path from the direct current power supply 1 through the inductor 2, diode 4, and capacitor 5 to the direct current power supply 1
Data Source
AI summary
A power converting device, in one possible configuration, includes a chopper circuit with a first semiconductor switching device, a fast recovery diode, and an inductor of which one end is connected to a connection point connecting between the first semiconductor switching device and fast recovery diode; a series circuit, connected in parallel with the fast recovery diode, including a rectifying diode with a greater reverse recovery loss and a smaller forward voltage drop than those of the fast recovery diode, and a second semiconductor switching device. The second semiconductor switching device has a lower breakdown voltage and a smaller forward voltage drop than those of the first semiconductor switching device, is configured to turn on when the first semiconductor switching device is turned off, and is configured to turn off at a timing before the first semiconductor switching device shifts from an off-state to an on-state.