Gate Drive Circuitry Using Vsd Tables for Junction Temperature Sensing
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Solution Overview
Problem
Existing gate drive circuitries struggle to accurately estimate the temperature of semiconductor switching elements or the current flowing through them, leading to potential damage due to delayed overtemperature or overcurrent detection.
Innovation Solution
A gate drive circuitry that includes a voltage detection circuitry, a controller, and a gate driver, utilizing tables to uniquely identify junction temperature and current based on detected voltage values at specific timings during asynchronous and synchronous rectification states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is provided on the chip, package, or heat sink to detect temperature, then overtemperature detection can be implemented, but a temperature difference occurs between the semiconductor switching element and the sensor due to thermal time constant, causing delayed detection and potential damage
Solution Approach 1:
The patent introduces an intermediary approach by using the body diode's forward voltage as a proxy indicator for junction temperature. Instead of directly measuring temperature with a sensor that has thermal lag, the system measures the forward voltage of the body diode during dead time periods, which directly reflects the junction temperature without thermal time constant delays. This intermediary measurement method eliminates the detection time delay while maintaining reliability.
Solution Approach 2:
The patent replaces the thermal-based temperature sensing mechanism (which suffers from thermal time constant delays) with an electrical-based measurement method. By measuring the forward voltage of the body diode during dead time, the system substitutes mechanical/thermal measurement with electrical measurement, achieving instantaneous junction temperature detection without the delays inherent in thermal conduction-based sensing.
2Measurement precision
If a temperature sensor is installed to accurately monitor temperature, then temperature detection capability is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies the self-service principle by utilizing the body diode's inherent electrical characteristics (forward voltage) as a built-in temperature indicator. The semiconductor switching element itself provides the measurement information through its body diode during dead time periods, eliminating the need for external temperature sensors. This self-service approach maintains measurement precision while reducing device complexity and manufacturing cost.
Solution Approach 2:
The body diode serves multiple functions: it provides overcurrent protection during reverse recovery, and simultaneously serves as a temperature sensor through its forward voltage characteristic. By making the body diode multi-functional, the patent eliminates the need for separate temperature sensing components, thereby reducing device complexity while maintaining accurate temperature measurement capability.
3Reliability
If a temperature sensor is added to the system, then temperature monitoring is improved, but manufacturing cost increases due to additional components
Solution Approach 1:
The system uses the body diode's own forward voltage characteristic as an intrinsic temperature indicator, making the semiconductor device self-diagnostic for temperature monitoring. This eliminates the need for additional temperature sensor components, thereby maintaining reliable temperature monitoring while significantly reducing manufacturing cost and simplifying the manufacturing process.
Solution Approach 2:
The patent extracts the temperature sensing function from a separate physical sensor and embeds it within the existing body diode structure. By taking out the temperature monitoring capability from a standalone component and integrating it into the body diode's electrical characteristics, the system achieves reliable temperature monitoring without adding external components, thus reducing manufacturing cost.
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
Enables accurate estimation of semiconductor switching element temperature and current, allowing for timely control and preventing damage, while also reducing manufacturing costs by eliminating the need for temperature sensors.
Implementation Method 1
a first table indicating the first voltage in a correspondence between a first current and a junction temperature, the first current being a flow from the source terminal to the drain terminal when the semiconductor switching element is in an asynchronous rectification state
Data Source
AI summary
A controller of a gate drive circuitry includes: a Vsd table indicating a first voltage, which is a voltage between a drain terminal and a source terminal, in a correspondence between a first current and a first junction temperature; and a Vsd table indicating the first voltage in a correspondence between a second current and a second junction temperature. The first and second currents are currents flowing when a semiconductor switching element is in an asynchronous rectification state and a synchronous rectification state, respectively. The first and second junction temperatures are junction temperatures when the first and second currents flow through the semiconductor switching element, respectively. The controller uniquely specifies a junction temperature of the semiconductor switching element from the Vsd table by using two detection values of the first voltage detected individually in the asynchronous rectification state and the synchronous rectification state.