Transistor Half-Bridge Driver Delay Adjustment
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Solution Overview
Problem
Conventional half-bridge driver circuits face challenges in minimizing the delay time between control signals to prevent cross-conduction, which can lead to power dissipation and thermal issues, especially as temperature varies, often requiring additional sensing means and input pins.
Innovation Solution
A control circuit with a programmable delay adjustment mechanism that dynamically measures and decrements the delay time between input and phase signals to achieve optimal switching without cross-conduction, using a processing circuit and driver circuit to generate control signals and adjust the delay value iteratively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed delay time T_wait is used between control signals to prevent cross-conduction, then cross-conduction is avoided, but the delay time cannot be optimized for different temperature ranges and may be too high or too small
Solution Approach 1:
The patent implements a dynamic delay adjustment mechanism where the delay time T_wait is no longer fixed but can be adaptively modified based on temperature conditions. The control circuit includes a delay adjustment unit that receives temperature information and dynamically adjusts the delay parameter to maintain optimal prevention of cross-conduction across varying temperature ranges.
Solution Approach 2:
The patent changes the delay parameter T_wait from a constant value to a variable that responds to temperature changes. By introducing temperature-dependent parameter adjustment, the system adapts the delay time to compensate for temperature-induced variations in transistor switching characteristics, ensuring reliable cross-conduction prevention under different thermal conditions.
2Adaptability or versatility
If additional sensing means and input pins are added to sense cross-conduction current and adapt delay time, then temperature adaptability is improved, but device complexity increases
Solution Approach 1:
The patent integrates temperature sensing and delay adjustment functionality into the existing control circuit structure. The control circuit performs multiple functions: generating control signals, sensing temperature conditions, and dynamically adjusting delay parameters, all within a unified architecture that avoids adding separate dedicated sensing modules and input pins.
Solution Approach 2:
The patent merges the temperature sensing function and delay adjustment function into the existing control circuitry. Rather than adding independent sensing means and control pins, the system combines these functions with the existing pulse width modulation signal processing, allowing temperature-adaptive delay control without significantly increasing device complexity.
3Productivity
If the delay time T_wait is minimized to improve switching efficiency, then productivity increases, but cross-conduction risk increases requiring longer delay for safety
Solution Approach 1:
The patent applies dynamic adjustment to the delay time T_wait, allowing it to be minimized under conditions where cross-conduction risk is low (improving switching efficiency) while automatically increasing when temperature conditions indicate higher risk (maintaining reliability). This dynamic optimization resolves the contradiction between speed and safety.
Solution Approach 2:
The patent changes the delay parameter from a conservative fixed value to a dynamically optimized value based on temperature and operating conditions. By adjusting the delay parameter in real-time, the system achieves minimal delay for maximum efficiency when safe, while maintaining sufficient delay for cross-conduction prevention when necessary.
Data Source
AI summary
A method drives a transistor half-bridge. The method includes measuring a delay time between an edge of an input signal and an corresponding edge of a phase signal, and saving the delay time as a saved delay time value. The phase signal is the output of the transistor half-bridge. In the method, the following steps are repeated until the saved delay time value differs from the delay time by more than a given threshold:decrementing the delay-value of a programmable delay circuit and the saved delay time value by a given decrement, the programmable delay circuit coupled to a control terminal of a first transistor of the half-bridge, andmeasuring the delay time between an edge of the input signal and an corresponding edge of the phase signal.