Switching Power Source Dead Time Control Without Auxiliary Coil
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Solution Overview
Problem
Conventional switching power source devices fail to maintain proper operation when the auxiliary coil is removed from the insulation transformer, leading to erroneous load state detection and improper switching frequency adjustment due to the absence of coil voltage input for dead time adjustment.
Innovation Solution
A switching power source device with a dead time adjustment circuit that generates an ON trigger signal based on a predetermined dead time and a disable control circuit that detects the absence of coil voltage, disabling the dead time adjustment function when no coil voltage is present, thereby setting the dead time to the smallest width to prevent simultaneous turn-on of switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the auxiliary coil is removed from the insulation transformer to simplify the device structure, then device complexity is reduced, but the dead time adjustment circuit cannot properly detect load state and adjust dead time, leading to improper switching operation
Solution Approach 1:
The patent extracts the dead time adjustment function from the auxiliary coil dependency by providing a separate adjustment terminal that accepts external voltage signals. This allows the main transformer to be simplified without the auxiliary coil while maintaining the ability to adjust dead time through an independent interface.
Solution Approach 2:
The adjustment terminal serves multiple functions: it can accept voltage signals from various sources (auxiliary coil if present, external circuits, or fixed voltage sources) to control dead time adjustment. This multi-functionality allows the system to operate correctly whether or not an auxiliary coil is present.
2Productivity
If the dead time adjustment circuit continuously adjusts dead time based on terminal voltage changes, then switching operation is optimized for varying load conditions, but the circuit cannot distinguish between actual load changes and absence of auxiliary coil voltage input, leading to erroneous load state detection
Solution Approach 1:
The dead time adjustment circuit dynamically adapts its behavior based on the presence or absence of voltage changes at the adjustment terminal. When voltage changes are detected, it adjusts dead time accordingly; when no changes occur (indicating auxiliary coil removal), it maintains a fixed dead time setting, thus adapting to different operational configurations.
Solution Approach 2:
The circuit uses feedback from the adjustment terminal voltage to determine whether to perform dead time adjustment. The absence of voltage changes provides feedback that the auxiliary coil is removed, causing the circuit to disable automatic adjustment and use a predetermined dead time, thereby preventing erroneous load state detection.
3Productivity
If the dead time is set to the smallest width to prevent simultaneous turn-on of switching elements, then switching efficiency is improved, but the risk of simultaneous turn-on increases when load conditions vary
Solution Approach 1:
The dead time dynamically adjusts between a minimum value and a larger value based on operating conditions. When the auxiliary coil is present and load variations occur, the dead time increases to prevent simultaneous turn-on. When the auxiliary coil is removed and conditions are stable, the dead time remains at the minimum value to maximize switching efficiency.
Solution Approach 2:
The circuit changes the dead time parameter based on the detection of voltage changes at the adjustment terminal. By modifying this critical timing parameter according to the presence or absence of the auxiliary coil, the system optimizes switching efficiency while preventing harmful simultaneous turn-on events under varying load 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
Ensures normal switching operation even without the auxiliary coil, preventing erroneous load state detection and maintaining optimal switching frequency, thus ensuring proper operation in heavy load states.
Implementation Method 1
the first switching element switches an input voltage to accumulate electric power in an inductor
Implementation Method 2
the second switching element is switched to transfer the electric power accumulated in the inductor to an output capacitor using resonance of the inductor
Data Source
AI summary
A switching power source device IS capable of guaranteeing a normal switching operation even when the input of a coil voltage used for adjusting a dead time is eliminated. The switching power source device includes a dead time adjustment circuit that generates an ON trigger signal that regulates an ON timing of one of the first and second switching elements after elapse of a predetermined dead time from an OFF timing of the other switching element and that adjusts the dead time according to a temporal change of a terminal voltage detected from an auxiliary coil of an inductor; and a disable control circuit that detects a temporal change of the coil voltage during activation and disables a function of the dead time adjustment circuit adjusting the dead time when the coil voltage does not temporally change.