Switch Drive Circuit With Divided Voltage Surge Detection
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Solution Overview
Problem
Existing drive circuits for power converters face challenges in reducing size while maintaining performance, as they require increased withstand voltage for inter-terminal voltage detection, leading to larger voltage detectors and drive circuits.
Innovation Solution
A drive circuit that includes a voltage divider and a differential circuit with input terminals to which the inter-terminal voltage is inputted, outputting an analog voltage based on the voltage difference, allowing for reduced withstand voltage and size through voltage division and amplification, and a comparator that sets the gate charge transfer rate based on the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the withstand voltage of the voltage detector is increased to detect inter-terminal voltage, then the detection capability is improved, but the size of the voltage detector and drive circuit increases
Solution Approach 1:
The voltage detection function is segmented into two parts: a voltage divider that divides the inter-terminal voltage into a lower voltage signal, and a differential circuit that detects the divided voltage. This segmentation allows the detection circuit to operate at lower voltage levels, reducing the required withstand voltage and circuit size while maintaining detection capability.
Solution Approach 2:
The voltage divider acts as an intermediary element between the high-voltage inter-terminal voltage and the differential circuit. It transforms the high voltage into a lower voltage that the differential circuit can handle, enabling size reduction of the detection circuit while preserving the ability to detect voltage variations.
2Speed
If the gate charge transfer rate is increased to improve switching speed, then the switching performance is improved, but the surge voltage increases
Solution Approach 1:
The gate charge transfer rate is made dynamic rather than fixed. The differential circuit continuously monitors the inter-terminal voltage and adjusts the gate charge transfer rate in real-time based on the detected voltage conditions. This dynamic adjustment allows the system to achieve high switching speed when safe, while automatically reducing the transfer rate to prevent surge voltage when conditions require it.
Solution Approach 2:
A feedback mechanism is implemented where the differential circuit's voltage detection output feeds back to control the gate charge transfer rate. This closed-loop control enables the system to respond to changing voltage conditions and adjust the switching characteristics accordingly, balancing switching performance with surge voltage prevention.
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 achieves size reduction of both the differential circuit and the drive circuit while maintaining effective surge voltage detection and switching performance without the need for an analog-to-digital converter.
Implementation Method 1
a differential circuit that has a first input terminal and a second input terminal to which the inter-terminal voltage that is divided by the voltage divider is inputted, and outputs an analog voltage that is based on a voltage difference between the first input terminal and the second input terminal
Implementation Method 2
The drive circuit divides an inter-terminal voltage of the switch, and includes a differential circuit that has a first input terminal and a second input terminal to which the inter-terminal voltage that is divided by the voltage divider is inputted
Data Source
AI summary
A drive circuit drives a switch configuring a power converter. The drive circuit divides an inter-terminal voltage of a switch. The drive circuit includes a differential circuit having first and second input terminals to which the divided inter-terminal voltages are inputted. The differential circuit outputs an analog voltage based on a voltage difference between the input terminals. The differential circuit executes reset of the output voltage, and with the voltage difference when reset is canceled after reset is executed as a reference voltage, outputs an analog voltage in which an amount of change from the reference voltage is multiplied by an amplification factor. The drive circuit outputs a binary signal based on comparison results between a threshold and the analog voltage outputted from the differential circuit, and sets a transfer rate of a gate charge of the switch when a driving state is switched, based on the output signal thereof.