Reverse Conducting Semiconductor Device Gate Voltage Control
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Solution Overview
Problem
Existing power supply devices face challenges in reducing reverse recovery loss and constant loss in switching elements due to high reverse recovery current and forward voltage drop, particularly when using reverse conducting semiconductor devices, which can lead to heat generation and potential damage.
Innovation Solution
The implementation of a power supply device configuration that includes reverse conducting semiconductor devices with trench gate electrodes and a gate voltage control circuit, where the trench gate electrodes of the IGBT and diode domains are connected to the same gate voltage control circuit, and a negative voltage is applied to the trench gate electrodes during return current flow to reduce the forward voltage drop and reverse recovery current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the return diode has low forward voltage drop, then constant loss is reduced, but reverse recovery current increases causing high voltage and potential damage to switching elements
Solution Approach 1:
A low lifetime layer is formed in the cathode region before the diode operates, which preliminarily reduces the carrier lifetime. This preliminary action ensures that when the diode conducts return current, it maintains low forward voltage drop while limiting the reverse recovery current magnitude, preventing high voltage spikes that could damage switching elements.
Solution Approach 2:
The low lifetime layer is specifically formed only in the cathode region of the return diode, not throughout the entire device. This local modification allows the diode to maintain its primary function of providing a low impedance path for return current (reducing constant loss) while locally controlling the carrier recombination rate to limit reverse recovery current.
2Device complexity
If reverse conducting semiconductor devices are used, then device integration is improved, but reverse recovery loss and constant loss increase due to high reverse recovery current and forward voltage drop
Solution Approach 1:
Within the reverse conducting semiconductor device, the low lifetime layer is formed specifically in the diode element domain's cathode region, while the IGBT domain maintains its normal structure. This local quality modification allows the device to integrate both switching and rectifying functions while the low lifetime layer specifically addresses the reverse recovery loss in the diode portion.
Solution Approach 2:
The carrier lifetime parameter is modified in the cathode region by forming a low lifetime layer, which changes the recombination characteristics. This parameter change reduces both the forward voltage drop (by improving carrier injection efficiency) and the reverse recovery current (by reducing stored charge), thereby reducing reverse recovery loss while maintaining integration benefits.
3Device complexity
If reverse conducting semiconductor devices are used, then device integration is improved, but heat generation increases due to forward voltage drop and reverse recovery current
Solution Approach 1:
By forming a low lifetime layer in the cathode region, the carrier lifetime parameter is reduced, which decreases both the forward voltage drop during conduction and the reverse recovery current during switching. Since power loss (and thus heat generation) is proportional to both voltage drop and current, this parameter change directly reduces heat generation while preserving the integrated device structure.
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 approach effectively reduces the forward voltage drop and reverse recovery current, minimizing heat generation and electrical power loss, thereby enhancing the reliability and efficiency of the power supply device.
Implementation Method 1
a trench gate electrode extending from a surface to the drift region... controlling a quantity of minority carriers in the drift region when a voltage is applied to the trench gate electrode
Data Source
Figure 1a~1b
Figure 2
Figure 3a~3b
AI summary
In a reverse conducting semiconductor device, which forms a composition circuit, a positive voltage that is higher than a positive voltage of a collector electrode may be applied to an emitter electrode. In this case, in a region of the reverse conducting semiconductor device in which a return diode is formed, a body contact region functions as an anode, a drift contact region functions as a cathode, and current flows from the anode to the cathode. When a voltage having a lower electric potential than the collector electrode is applied to the trench gate electrode at that time, p-type carriers are generated within the cathode and a quantity of carriers increases within the return diode. As a result, a forward voltage drop of the return diode lowers, and constant loss of electric power can be reduced. Electric power loss can be reduced in a power supply device that uses such a composition circuit in which a switching element and the return diode are connected in reverse parallel.