Initial Voltage Establishing Circuit for Switching Converters
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Solution Overview
Problem
Conventional switching voltage converters experience damage due to huge inrush currents at the beginning of activation, as the duty cycle is expanded to maximum, causing excessive current flow.
Innovation Solution
An initial voltage establishing circuit with a current supplying circuit, current adjusting circuit, charge/discharge control circuit, and oscillating signal generating circuit generates a pulse signal with a gradually increasing duty cycle to establish an initial output voltage, preventing the maximum duty cycle expansion and thus reducing inrush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the duty cycle is expanded to maximum at the beginning of activation, then the output voltage can be raised quickly, but huge inrush current is generated that damages the circuit
Solution Approach 1:
The patent applies preliminary action by establishing an initial output voltage before normal switching operation begins. The initial voltage establishing circuit pre-charges the output capacitor to a predetermined voltage level, so that when the main switching sequence starts, the duty cycle does not need to be expanded to maximum, thereby avoiding huge inrush current while still achieving quick voltage establishment.
Solution Approach 2:
The patent employs dynamics by transitioning from a static maximum duty cycle approach to a dynamic, staged duty cycle sequence. The duty cycle evolves through multiple stages: initial stage with low duty cycle for safe voltage establishment, intermediate stages with progressively increasing duty cycle, and finally normal operation stage. This dynamic adjustment allows the system to balance speed and safety.
2Productivity
If the duty cycle is expanded to maximum to raise output voltage, then voltage regulation speed is improved, but circuit reliability deteriorates due to inrush current damage
Solution Approach 1:
The initial voltage establishing circuit performs preliminary action by pre-charging the output capacitor to a predetermined initial voltage before the main voltage regulation process begins. This preliminary voltage establishment eliminates the need for maximum duty cycle expansion during startup, thereby maintaining high productivity while preserving circuit reliability.
Solution Approach 2:
The patent applies beforehand cushioning by using the initial voltage establishing circuit to cushion against the harmful effects of inrush current. The circuit预先 establishes a safe initial voltage level, cushioning the system from the shock of maximum duty cycle activation and protecting components from damage.
3Loss of time
If the output voltage is established immediately at maximum level, then the activation time is reduced, but the circuit generates harmful inrush current
Solution Approach 1:
The patent applies segmentation by dividing the voltage establishment process into multiple sequential stages: initial voltage establishment stage, intermediate voltage increase stages, and normal operation stage. Each stage uses an appropriate duty cycle level, segmenting the harmful maximum duty cycle application into manageable portions that avoid inrush current while maintaining reasonable activation time.
Solution Approach 2:
The initial voltage establishing circuit performs preliminary action during the first stage, establishing a safe baseline voltage before subsequent stages increase the voltage to full level. This preliminary establishment prevents the need for immediate maximum voltage application, eliminating inrush current while keeping total activation time acceptable.
Data Source
AI summary
An initial voltage establishing circuit has a current supplying circuit, a current adjusting circuit, a charge/discharge control circuit, and an oscillating signal generating circuit. The current supplying circuit provides a charge current and a discharge current. The current adjusting circuit adjusts the charge current and the discharge current. The charge/discharge control circuit selectively allows the charge current and the discharge current to flow through. The oscillating signal generating circuit employs the charge current and the discharge current to generate an initial voltage establishing signal such that a duty cycle of the initial voltage establishing signal gradually increases. The initial voltage establishing signal is applied to a switching voltage converter for establishing an initial output voltage.