Drive Circuit Ensuring Diode Clamping for Power Device Control
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Solution Overview
Problem
Existing drive circuits for power devices experience erroneous operations due to negative voltage generation at the node between power switching devices, leading to incorrect resetting and setting of the high-side control circuit caused by ringing voltages.
Innovation Solution
A drive circuit comprising a set-side and reset-side level shift circuit that generates level-shifted signals, a control circuit that outputs drive signals based on these signals to ensure proper operation of the power device, and an ensuring circuit that manages impedance to prevent erroneous operations by clamping and reverse recovery phenomena in diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a level shift circuit is used to generate drive signals for the high-side power switching device, then the power device can be controlled to turn on and off, but negative voltage generation at the node causes ringing that leads to erroneous operation of the control circuit
Solution Approach 1:
The patent introduces an ensuring circuit as an intermediary component between the level shift circuit and the high-side control circuit. This ensuring circuit includes ensuring diodes that clamp the voltages at the set and reset output terminals, preventing the ringing voltage from directly affecting the control circuit's threshold voltage comparison. The ensuring circuit acts as a buffer that isolates the control circuit from the harmful negative voltage effects while still allowing proper control signals to pass through.
Solution Approach 2:
The ensuring circuit applies preliminary protective action by clamping the voltages at the set and reset output terminals before the ringing can cause erroneous operation. The ensuring diodes are positioned to preemptively prevent the voltage from exceeding the threshold voltage, thereby preventing the harmful effect before it can occur. This is a proactive measure that stops the negative voltage from propagating to the control circuit in the first place.
2Power
If the high-side control circuit operates at high voltage to drive the power switching device, then the power device can be driven effectively, but ringing voltage exceeds the threshold voltage causing erroneous setting and resetting
Solution Approach 1:
The ensuring circuit serves as an intermediary that protects the control circuit from high voltage ringing effects. The ensuring diodes clamp the voltage at the set and reset output terminals to remain below the threshold voltage, thereby preventing erroneous operation while allowing the high-side control circuit to continue operating at high voltage levels necessary for effective power device driving.
Solution Approach 2:
The patent changes the voltage parameters at the set and reset output terminals by introducing voltage clamping through ensuring diodes. This modifies the voltage waveform characteristics, specifically limiting the peak voltage excursions caused by ringing to remain below the threshold voltage, thereby ensuring reliable operation of the control circuit while maintaining high voltage operation for power device driving.
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 solution ensures that the high-side control circuit operates correctly even after negative voltage elimination, preventing erroneous operations and maintaining the drive signal state before the negative voltage occurrence.
Implementation Method 1
an ensuring circuit that ensures, based on the drive signal, that the control circuit turns on the power device based on the level-shifted set signal, and turns off the power device based on the level-shifted reset signal
Data Source
AI summary
A drive circuit of a power device, including a set-side level shift circuit that receives a set signal and generates a level-shifted set signal, a reset-side level shift circuit that receives a reset signal and generates a level-shifted reset signal, a control circuit that is connected to the set-side level shift circuit and the reset-side level shift circuit, and that outputs a drive signal, a level of the drive signal changing between a first logic level for turning off the power device based on the level-shifted reset signal and a second logic level for turning on the power device based on the level-shifted set signal, and an ensuring circuit that ensures, based on the drive signal, that the control circuit controls to turn on the power device responsive to the level-shifted set signal, and to turn off the power device responsive to the level-shifted reset signal.