MOSFET Gate Current Pulses to Cut Miller Switching Losses
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Solution Overview
Problem
Existing power semiconductor devices, such as MOSFETs, suffer from significant switching losses due to the Miller effect, which occurs when voltage and current transitions are not synchronized, leading to inefficient power consumption and heating during on/off switching processes.
Innovation Solution
Implementing a controlled current pulse source to concurrently charge and discharge the gate-source and gate-drain capacitances of MOSFETs using positive and negative current pulses, respectively, to synchronize voltage and current transitions, thereby reducing the Miller effect and improving switching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If voltage control signals are used to switch power semiconductor devices, then the devices can be controlled to switch on and off, but significant switching losses occur due to the Miller effect causing voltage and current transitions to be unsynchronized
Solution Approach 1:
The patent changes the control parameter from voltage to current. By using current pulses instead of voltage signals to control the gate, the invention directly synchronizes the current transitions with the voltage transitions, eliminating the Miller effect problem. The current-controlled switching ensures that current flows only when voltage is low and vice versa, minimizing switching losses.
Solution Approach 2:
The patent substitutes the conventional voltage-based electrical control mechanism with a current-based control mechanism. This substitution fundamentally changes how the switching device is controlled, replacing the voltage-driven gate control with current-driven gate control, which directly addresses the timing synchronization issue between voltage and current transitions.
2Power
If conventional voltage control is used, then the switching process can be initiated, but the overlap between voltage and current transitions maximizes power consumption during switching
Solution Approach 1:
The invention changes the control parameter from voltage to current, which fundamentally alters the switching dynamics. By using current pulses to control the gate, the switching transitions are synchronized such that current rises only after voltage falls and voltage rises only after current falls, minimizing the overlap period and thus reducing power consumption during switching.
3Productivity
If short current pulses are used for switching, then switching losses are reduced and switching speed is increased, but additional circuitry may be required for current pulse generation
Solution Approach 1:
The invention enables the power semiconductor device to control its own switching through current pulses applied to the gate. The current-controlled switching mechanism allows the device to naturally synchronize its voltage and current transitions, reducing switching losses and improving switching speed without requiring complex external control circuitry.
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 current pulse control method significantly reduces switching losses and increases switching speed, particularly during the turn-on process, while minimizing the need for additional circuitry and providing electrical isolation and immunity to electromagnetic interference.
Implementation Method 1
concurrently charge and discharge the gate-source and gate-drain capacitances of MOSFETs using positive and negative current pulses
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3B
AI summary
A circuit for switching a power semiconductor device has a power semiconductor device. A controlled current pulse source is coupled to the power semiconductor device generating a positive current pulse to switch ON the power semiconductor device and a negative current pulse to switch OFF the power semiconductor device.