Intermediate Circuit Capacitor Charging via Phase-Cut Rectifier Control
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Solution Overview
Problem
Existing methods for charging intermediate circuit capacitors in welding devices are inefficient and require separate devices for limiting charging current, leading to non-compact and costly systems.
Innovation Solution
Implementing phase-cut control to gradually increase electrical voltage at the intermediate circuit capacitor, eliminating the need for separate devices and reducing losses, using a semi-controlled rectifier bridge with voltage-dependent control of thyristors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a series resistor is used to limit charging current, then the charging current is limited, but the system becomes more complex and costly with separate devices required
Solution Approach 1:
The patent combines the charging current limitation function with the semi-controlled rectifier bridge by utilizing the thyristors' inherent current-limiting capability during the charging phase. This merging eliminates the need for separate series resistors or dedicated current-limiting devices, thereby reducing system complexity and cost while maintaining reliable current limitation during capacitor charging.
Solution Approach 2:
The semi-controlled rectifier bridge is designed to perform multiple functions: it serves as both the main power conversion device and the charging current limiter. The thyristors in the rectifier bridge can operate in different modes - during normal operation they provide full power conversion, and during charging they inherently limit current through their firing angle control. This multi-functionality eliminates the need for separate dedicated components.
2Reliability
If separate devices are used for providing limited charging current, then current limitation is achieved, but the system becomes less compact and more costly
Solution Approach 1:
The patent merges the charging current control function into the existing semi-controlled rectifier bridge structure. By using the thyristors' phase-controlled conduction特性, the system achieves reliable current limitation during capacitor charging without requiring separate current-limiting devices. This integration reduces both the component count and system cost while improving compactness.
Solution Approach 2:
The semi-controlled rectifier bridge serves itself by utilizing its own thyristors to perform the dual function of power conversion and charging current limitation. The thyristors inherently limit the charging current through their controlled conduction angle, eliminating the need for external current-limiting components and reducing overall system cost and complexity.
3Productivity
If conventional charging methods are used, then charging is achieved, but energy losses are high
Solution Approach 1:
The patent changes the operating parameters of the rectifier bridge by controlling the thyristor firing angles during the charging phase. By adjusting the firing angle, the system optimizes the charging current waveform and reduces unnecessary energy losses. This parameter control allows for efficient energy transfer to the intermediate circuit capacitor while minimizing resistive losses and improving overall charging efficiency.
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
Achieves a compact and cost-effective welding system by efficiently charging the intermediate circuit capacitor with low losses and enabling a standby mode with reduced energy consumption.
Implementation Method 1
a semi-controlled rectifier bridge (408) for converting the alternating voltage into a direct voltage
Implementation Method 2
an intermediate circuit capacitor (410) for smoothing the direct voltage
Implementation Method 3
The phase cuts or phase cuts become successively larger to increase the electrical voltage at the intermediate circuit capacitor in a controlled manner
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The method (100) involves feeding voltage (102) from a chopping section of a half-cycle of alternate current (AC) voltage into an intermediate circuit capacitor, where the chopping section begins at phase-related starting time. The voltage from another chopping section of another half-cycle of another AC voltage following the former half-cycle is fed (104) into the intermediate circuit capacitor, where the latter chopping section begins at another phase-related starting time that is earlier than the former phase-related starting time. Independent claims are also included for the following: (1) a control device for charging an intermediate circuit capacitor for a welding set (2) a computer program comprising a set of instructions for charging an intermediate-circuit capacitor.