Multi-Level Gate Return Loop for Power Switch di/dt Control
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Solution Overview
Problem
Existing power semiconductor devices face challenges in achieving optimal switching performance due to the need to compromise between low and high switching currents, and closed-loop gate drive control methods are complex and prone to stability issues.
Innovation Solution
The proposed solution involves a power semiconductor device with multiple inductance/resistance pairs and a control circuit that forms a gate drive current return loop through these pairs, allowing for multi-level di/dt control and reducing switching losses and turn-on/off time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed-value gate resistors are used to control switching transient, then switching performance can be controlled, but switching performance must be compromised between low and high switching currents
Solution Approach 1:
The gate resistor is divided into multiple segmented resistors that can be independently controlled. This segmentation allows different resistance values to be applied to different portions of the gate drive current, enabling independent optimization for both low and high switching currents without compromise.
Solution Approach 2:
The gate resistance is made dynamically adjustable through multiple controllable switches that can selectively connect different resistor segments. This dynamic configuration allows the system to adapt the gate resistance in real-time based on switching conditions, optimizing performance across varying current levels.
2Measurement precision
If closed-loop gate drive control method is used to control switching transient, then good control of switching transient can be achieved, but design bandwidth must be very high resulting in stability, complexity and reliability challenges
Solution Approach 1:
The invention replaces complex closed-loop control circuits with simpler open-loop controllable resistor segments. This approach achieves effective switching transient control without requiring high-bandwidth feedback circuits, thereby reducing design complexity and improving reliability.
Solution Approach 2:
Controllable switches are introduced as intermediary elements between the control signal and the gate drive circuit. These switches enable precise control of the gate resistance without requiring complex feedback mechanisms, simplifying the overall control architecture while maintaining effective switching transient control.
3Object-generated harmful factors
If freewheeling diode is used with the switch, then reverse recovery current can be reduced by slow transition, but turn-on power loss increases
Solution Approach 1:
The gate resistance is pre-adjusted to optimized values before switching events occur. By having pre-configured resistor segments that can be selectively engaged, the system prepares the optimal resistance value in advance for each switching condition, enabling controlled transition speeds that minimize both reverse recovery current and power loss.
Solution Approach 2:
The gate resistance parameter is dynamically changed based on switching conditions. By adjusting the resistance value to match specific operating conditions, the system optimizes the trade-off between transition speed and reverse recovery current, minimizing both harmful effects simultaneously.
4Loss of energy
If power semiconductor device switches as fast as possible, then turn-on and turn-off power losses are minimized, but overshoot voltage increases requiring slow turn-off transient to avoid avalanche breakdown
Solution Approach 1:
The gate resistance is made dynamically adjustable with multiple controllable segments that can be selectively connected during turn-on and turn-off transitions. This dynamic control allows independent optimization of turn-on and turn-off characteristics, enabling fast switching with minimal power loss while controlling overshoot voltage through appropriate resistance selection during turn-off.
Solution Approach 2:
Different gate resistance values are applied periodically depending on the switching phase. The control circuit selectively engages different resistor segments during turn-on versus turn-off events, optimizing performance for each phase independently - minimizing power loss during turn-on and controlling overshoot during turn-off.
Data Source
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AI summary
A power semiconductor device comprising: a power semiconductor die forming a power switch, the power switch comprising an input pad, an output pad and a control pad; a collector power terminal coupled to the input pad of the power switch; an auxiliary gate terminal coupled to the control pad of the power switch; an emitter power terminal; two or more inductance/resistance pairs, wherein each inductance / resistance pair comprises a common stray inductance and a resistance which are arranged in series between the output pad of the power switch and the emitter power terminal; and a plurality of auxiliary emitter terminals that are coupled to both sides of the inductance/resistance pairs such that one auxiliary emitter terminal is coupled to one side of one inductance/resistance pair. Further, a control circuit for di/dt control of such power semiconductor device and an electronic device comprising such power semiconductor device are presented.