Isolated Gate Driver With Dynamic Slew Rate Feedback Control
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Solution Overview
Problem
Conventional isolated gate drivers for power devices in vehicles have limitations in controlling the slew rate of gate voltages, as they rely on external resistors with fixed resistance values, restricting the flexibility and accuracy of slew rate adjustment.
Innovation Solution
An isolated gate driver system that includes a PWM transmission unit, a low voltage logic block, an insulation part, a high voltage logic block, a slew rate controller, and a slew rate feedback unit, allowing for dynamic control of the slew rate based on PWM and control signals from a microcontroller unit, with feedback mechanisms to adjust the slew rate within a reference range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external resistors with fixed resistance values are used to control slew rate, then the circuit design is simple, but the slew rate control flexibility and precision deteriorate
Solution Approach 1:
The patent transforms the static fixed-resistor slew rate control into a dynamic control system. The slew rate controller receives control signals from a microcontroller unit and dynamically adjusts the slew rate of gate voltages based on operational conditions. This allows the system to adapt slew rates for different power devices and operating scenarios, resolving the contradiction between design simplicity and control flexibility.
Solution Approach 2:
The patent changes the control parameter from fixed resistance values to variable control signals. By using a slew rate controller that modulates the gate voltage slope according to control signals, the system can precisely adjust slew rates without changing physical resistor values. This enables flexible adaptation to different power devices and operating conditions while maintaining a relatively simple circuit architecture.
2Device complexity
If external resistors with fixed resistance values are used to control slew rate, then the component count is low, but the slew rate precision deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the slew rate controller monitors and adjusts the gate voltage slew rate based on control signals from the microcontroller unit. This closed-loop control ensures precise slew rate management, allowing the system to achieve accurate slew rate control without relying on multiple external resistors with different values.
Solution Approach 2:
The patent replaces the mechanical approach of using multiple physical resistors with different resistance values with an electronic control system. The slew rate controller uses electronic signal processing to achieve precise slew rate control, eliminating the need for multiple discrete resistor components while improving precision through programmable control parameters.
3Reliability
If fixed slew rate control is used, then the system reliability is adequate, but the ability to handle operational conditions like overcurrent and short circuits deteriorates
Solution Approach 1:
The patent enables dynamic adaptation to different operational conditions through the microcontroller unit that generates appropriate control signals for the slew rate controller. When overcurrent or short circuit conditions are detected, the system can dynamically adjust the slew rate to appropriate levels, preventing damage while maintaining normal operation during standard conditions. This resolves the contradiction between maintaining adequate reliability and adapting to various operational scenarios.
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 precise control of the turn-on and turn-off slope of power devices, reduces the need for external devices, and enhances the stability and efficiency of power devices by optimizing slew rate control, improving fuel efficiency and handling various operational conditions like overcurrent and short circuits.
Implementation Method 1
an insulation part for boosting the low voltage PWM signal and the low voltage control signal into a high voltage PWM signal and a high voltage control signal, respectively
Data Source
AI summary
According to the present invention, there is provided an isolated gate driver comprising: a low voltage part including a PWM transmission unit for receiving a PWM signal from a microcontroller unit and outputting a low voltage PWM signal, and a low voltage logic block for receiving a control signal from the microcontroller unit and outputting a low voltage control signal; an insulation part for boosting the low voltage PWM signal and the low voltage control signal into a high voltage PWM signal and a high voltage control signal, respectively; and a high voltage part insulated from the low voltage part by the insulation part, wherein the high voltage part including: a high voltage logic block for outputting a slew rate control signal in accordance with the high voltage control signal; a slew rate controller for controlling a slew rate of a gate voltage of a power device external to the isolated gate driver such that the gate voltage of the power device has the slew rate depending on the slew rate control signal at a rising edge or a falling edge; and a slew rate feedback unit including a slew rate measuring unit for measuring the slew rate of the gate voltage and allowing the slew rate controller to change the slew rate of the gate voltage.