Gate Drive Slope Control for EMI and Thermal Protection
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Solution Overview
Problem
Existing load drive slope control devices face challenges in reducing EMI noise while minimizing power loss and heat generation when drive transistors are turned on and off, particularly in high-temperature environments, which can lead to thermal destruction due to excessive heat generation.
Innovation Solution
A load drive slope control device is designed with a configuration that includes a pre-driver circuit, current sources with adjustable current values, and a temperature monitoring unit, allowing for controlled ascending and descending gradients of the gate voltage of the drive transistor, thereby optimizing the voltage waveform to reduce EMI noise and power loss, and protecting the transistor from high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ascending time and descending time are increased to reduce EMI noise, then the EMI noise is reduced, but the power loss and heat generation increase
Solution Approach 1:
The patent applies dynamics by making the current source values adjustable based on temperature conditions. The control unit dynamically changes the charging current and discharging current values according to the detected temperature, allowing the system to optimize between EMI noise reduction and power loss minimization in real-time. This resolves the contradiction by enabling the ascending and descending times to be adaptively controlled rather than fixed.
Solution Approach 2:
The patent changes the parameter of current source values based on temperature. When temperature is below a threshold, larger current values are used to achieve faster switching and reduce power loss. When temperature exceeds the threshold, smaller current values are used to increase switching time and reduce EMI noise. This parameter adjustment strategy resolves the contradiction by adapting the system behavior to environmental conditions.
2Object-affected harmful factors
If the ascending time and descending time are increased to reduce EMI noise, then the EMI noise is reduced, but the heat generation increases leading to thermal destruction
Solution Approach 1:
The patent implements feedback by using a temperature detection unit to continuously monitor the temperature and feed this information back to the control unit. The control unit then adjusts the current source values based on the detected temperature, creating a closed-loop control system. This feedback mechanism resolves the contradiction by preventing thermal destruction while managing EMI noise through adaptive control.
Solution Approach 2:
The system dynamically adjusts the switching characteristics based on real-time temperature conditions. When temperature is high, the system increases switching time to reduce EMI noise and prevent thermal destruction. When temperature is low, the system decreases switching time to reduce power loss. This dynamic adaptation resolves the contradiction between EMI noise reduction and heat generation prevention.
3Loss of energy
If the current source values are decreased to reduce power loss, then the power loss is reduced, but the ascending time and descending time increase causing more EMI noise
Solution Approach 1:
The patent changes the current source parameters based on temperature conditions. At low temperatures, larger current values are used to achieve fast switching and minimize power loss. At high temperatures, smaller current values are used to increase switching time and reduce EMI noise. This parameter change strategy resolves the contradiction by adapting to environmental conditions.
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 effectively reduces EMI noise, power loss, and heat generation, while preventing thermal damage to the drive transistor by adjusting current sources based on temperature, ensuring efficient operation and extended device lifespan.
Implementation Method 1
a temperature monitoring unit that monitors a temperature of the drive transistor
Implementation Method 2
an ascending time and a descending time for the waveform of a voltage driving a load via the charging or the discharging of the capacitance of an ON/OFF control terminal
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(b)
AI summary
Provided is a load drive slope control device that can reduce EMI noise, and power loss and heat generation when a drive transistor is turned on and off, and can prevent excessive high temperature-induced damage to the drive transistor at an excessive high temperature. Disclosed is a load drive control device including: a drive transistor that drives a load; a pre-driver that drives the drive transistor via an ON/OFF control terminal of the drive transistor; a capacitor that is connected to an input side of the pre-driver; a first current source that is ON/OFF controlled by a first signal, and generates current which is charged to the capacitor; and a second current source that is ON/OFF controlled by a second signal, and generates current for discharging the capacitor, in which an output voltage from the pre-driver is changed by charging or discharging the capacitor, the drive transistor is turned on and off by the output voltage from the pre-driver, and a linear ascending gradient and a linear descending gradient of the waveform of a voltage driving the load are obtained by turning on and off the drive transistor.