High Voltage Offset Detection Circuit for H-Bridge ZVS
Solution Overview
Problem
Existing high voltage H-bridge driver circuits face challenges in detecting voltage at the floating node, particularly when the high side switch is on, leading to potential hard switching and damage to switches due to high across voltages.
Innovation Solution
A high voltage offset detection circuit incorporating a high voltage device with a ZVS generator, a bootstrap capacitor, and a programmable load element, which detects voltage changes at the floating node even when the high side switch is on, triggering a ZVS signal to prevent hard switching by adjusting switch timing and resonant frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a VS offset detection circuit is used to detect voltage at the floating node, then hard switching can be avoided, but the circuit can only detect voltage when the high side switch is off
Solution Approach 1:
The patent applies the Dynamics principle by making the high voltage device dynamically switchable between on and off states. The detection circuit controls the high voltage device to be turned on during specific phases to enable voltage detection when the high side switch is on, and turned off during other phases for normal operation. This dynamic state change allows the circuit to adapt its detection capability across different operating conditions, resolving the contradiction between reliability and adaptability.
2Power
If the high side switch is switched with high across voltage, then the circuit can operate at high voltage, but high current is generated that may damage the switches
Solution Approach 1:
The patent applies the Preliminary action principle by using the detection circuit to detect voltage changes at the floating node before the high side switch is turned on. When voltage change is detected indicating the low side switch just turned off, the control circuit generates a ZVS signal to delay or adjust the high side switch turn-on timing. This preliminary detection and proactive control prevents hard switching conditions before they occur, protecting the switches from damage while maintaining high voltage operation capability.
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
Effectively prevents hard switching by accurately detecting voltage at the floating node during both high and low side switch states, ensuring safe operation and extending the lifespan of switches in high voltage applications.
Implementation Method 1
The high voltage device has an input terminal, an output terminal, a control terminal, and a parasitic capacitance existing between the input terminal and the output terminal of the high voltage device. The input terminal of the high voltage device receives a voltage related to the voltage at the floating node
Implementation Method 2
a bootstrap capacitor connected between a high side power source and the floating node
Data Source
AI summary
A high voltage H-bridge driver circuit has a high voltage terminal and a floating node to be connected with a high side switch therebetween. When turning on the high side switch, a high voltage offset detection circuit detects a voltage related to the voltage at the floating node for triggering a zero voltage switching signal.