Switch Drive Circuit Reducing LC Resonance
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Solution Overview
Problem
Existing driving circuits for voltage-controlled switches experience LC resonance issues due to voltage differences between output terminals of switches connected in parallel, leading to potential malfunctions and increased power loss when switching rates are lowered to mitigate these issues.
Innovation Solution
The implementation of a drive circuit with charge and discharge paths for each voltage-controlled switch, including charging and discharging side elements that restrict current flow to one direction, reducing LC resonance by preventing unwanted current flows in loop paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching rate is lowered to mitigate LC resonance, then switch safety is improved, but power loss increases
Solution Approach 1:
A capacitor is introduced as an intermediary component connected between the output terminals of parallel switches. This capacitor absorbs voltage differences and suppresses LC resonance between the inductance of loop paths and capacitance of gate-output terminals, thereby protecting switches from resonance-induced malfunctions without requiring reduced switching rates.
Solution Approach 2:
The harmful LC resonance effect is extracted and isolated by providing separate charge paths and discharge paths for each switch's gate. By controlling the timing of gate charge and discharge currents individually, the resonance caused by simultaneous switching of parallel switches is eliminated, allowing high switching rates to be maintained without increasing power loss.
2Power
If switches are connected in parallel to increase current capacity, then power handling is improved, but voltage difference and LC resonance occur
Solution Approach 1:
A capacitor is introduced as an intermediary component connected between the output terminals of parallel switches. This capacitor absorbs voltage differences and suppresses LC resonance between the inductance of loop paths and capacitance of gate-output terminals, thereby protecting switches from resonance-induced malfunctions without requiring reduced switching rates.
Solution Approach 2:
The gate control circuitry is segmented into independent charge paths and discharge paths for each parallel switch. By individually controlling the gate charge and discharge timing of each switch, the invention eliminates simultaneous switching events that cause voltage differences and LC resonance, while maintaining the high current capacity provided by parallel connection.
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 effectively reduces LC resonance in both charging and discharging side loop paths, minimizing the risk of switch malfunctions and power loss while maintaining efficient switching operations.
Implementation Method 1
at least either, a charging side element (33A, 33B; 42A, 42B; 44A, 44B) provided for each voltage controlled switch, and disposed on a charging side loop path having the gate, a part of the charge path and the output terminal, restricting a current flow to be in one direction
Implementation Method 2
LC resonance occurs between an inductance component of the above-mentioned loop path and a capacitance component of gate-output terminal
Data Source
AI summary
The drive circuit for driving voltage controlled switches includes: charge path connected to gate of the switch, through which gate charge current flows to turn the switch ON; discharge path connected to the gate and output terminal of the switch, through which gate discharge current flows to turn the switch OFF; and at least either, a charging side element disposed on charging side loop path having the gate, a part of the charge path and the output terminal, restricting current flow to be in one direction and not disturbing current flow of charge current; or a discharging side element disposed on a discharging side loop path having the gate, a part of the discharge path and the output terminal, restricting a current flow to be in one direction and not disturbing a current flow of discharge current.