AC/DC Converter Inrush Current Limitation Thyristor Control
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Solution Overview
Problem
Existing AC/DC converter architectures face challenges in limiting inrush current peaks during starting phases, particularly when a voltage-doubling function is required, as they often result in increased losses and complex control systems.
Innovation Solution
The proposed solution involves an AC/DC converter circuit with controllable rectifying elements, such as cathode-gate and anode-gate thyristors, coupled with capacitive elements and a switch to manage inrush currents, allowing for voltage-doubling functionality while minimizing losses and simplifying control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rectifying bridge with capacitive elements is used to achieve voltage-doubling function, then the DC voltage output is improved, but inrush current peaks increase during starting phases
Solution Approach 1:
A resistive element is introduced as an intermediary component between the AC voltage source and the rectifying bridge. This resistor limits the inrush current during startup by providing impedance in the charging path of the capacitive elements, while not significantly affecting the normal operation of the voltage-doubling function.
Solution Approach 2:
The resistive element is activated preliminarily during the starting phase to limit inrush current. Once the capacitive elements are charged and normal operation begins, the resistive element is bypassed or its effect is minimized, allowing efficient power conversion without continuous power loss.
2Object-affected harmful factors
If controllable rectifying elements are added to limit inrush current, then inrush current is reduced, but device complexity increases
Solution Approach 1:
The circuit is designed to automatically manage inrush current limitation without requiring complex external control systems. The resistive element inherently limits current during startup, and the circuit topology itself provides the control mechanism, eliminating the need for additional control electronics or complex coordination between multiple components.
3Object-affected harmful factors
If a resistive element is used to limit inrush current during starting phase, then inrush current is limited, but energy losses increase
Solution Approach 1:
The resistive element is used only preliminarily during the starting phase when inrush current needs limitation. Once the capacitive elements are charged, the resistive element is bypassed or its impact is minimized, so energy losses occur only temporarily during startup rather than continuously during normal operation.
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
This configuration effectively limits inrush currents during startup and steady-state operations, reducing energy losses and simplifying control systems by using thyristors to manage inrush currents, enabling efficient voltage-doubling and follower modes without the need for complex phase control.
Implementation Method 1
a resistive element coupling a first input terminal of the rectifying bridge to a first terminal receiving an AC voltage
Implementation Method 2
The first and second rectifying elements are cathode-gate thyristors... the first rectifying element is an anode-gate thyristor controllable by extraction of a gate current and the second rectifying element is a cathode-gate thyristor controllable by injection and/or extraction of a gate current
Implementation Method 3
the gates of the thyristors are controlled by a same transformer, excited by an AC signal
Data Source
AI summary
An AC/DC converter receives an AC voltage at a first terminal and a second terminal. A rectifying bridge has a first input terminal coupled via a resistive element to the first terminal and a second input terminal connected to the second terminal, with output terminals of the rectifying bridge coupled to third and fourth terminals of the converter for generating a DC voltage. A first controllable rectifying thyristor couples the first terminal to the third terminal and a second controllable rectifying thyristor couples the fourth terminal to the first terminal. The resistive element functions as an inrush protection device during a first phase when the thyristors are turned off. In a second phase, the thyristors are selectively actuated.