DC-Link Capacitor Precharge Circuit Without Resistors
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Solution Overview
Problem
Existing pre-charging circuits for DC-link capacitors in high-voltage DC distribution systems rely on resistors, which are costly and may not be suitable for all applications due to size constraints and reliability issues with electromechanical switches.
Innovation Solution
A pre-charging circuit that utilizes semiconductor switches, inductors, and a diode in parallel with the capacitor, where at least one inductor can be parasitic wiring inductance, eliminating the need for a resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is used in the pre-charging circuit, then the DC-link capacitor can be pre-charged, but the cost increases and size constraints are not met
Solution Approach 1:
The patent extracts and eliminates the resistor from the pre-charging circuit. By removing the resistor component entirely and replacing it with a controlled semiconductor switch topology, the circuit achieves pre-charging functionality without the cost, size, and reliability issues associated with resistors.
Solution Approach 2:
The patent replaces the traditional resistive pre-charging mechanism with a semiconductor-based electronic control system. The semiconductor switches (IGBTs or MOSFETs) and control circuitry substitute for the passive resistor, enabling active control of the pre-charging process.
2Device complexity
If an electromechanical switch is used, then the circuit can be simplified, but reliability decreases due to switch failures
Solution Approach 1:
The patent replaces electromechanical switches with solid-state semiconductor switches (IGBTs or MOSFETs). This substitution eliminates the mechanical moving parts that are prone to failure, while maintaining circuit simplicity through the use of standard power electronic components and control circuitry.
3Reliability
If a resistor is used for pre-charging, then the capacitor can be charged safely, but the size constraints are not satisfied
Solution Approach 1:
The patent removes the resistor from the circuit, eliminating the need for large physical space to accommodate resistive pre-charging components. The semiconductor-based solution occupies significantly less space while achieving the same safe pre-charging function through controlled current limiting.
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 solution effectively pre-charges DC-link capacitors without the need for resistors, reducing costs and size constraints while maintaining reliability, and can be applied in various high-voltage DC distribution systems.
Implementation Method 1
a first inductor to be coupled to the first semiconductor switch and a first terminal of a capacitor, a second inductor to be coupled to the second semiconductor switch and a second terminal of the capacitor
Implementation Method 2
a diode coupled to the first semiconductor switch, the second semiconductor switch, the first inductor, and the second inductor, and coupled in parallel with the capacitor
Data Source
AI summary
A pre-charging circuit for charging a DC-link capacitor is provided. The pre-charging circuit may include a first semiconductor switch to be coupled to a first terminal of a high voltage source, a first inductor to be coupled to the first semiconductor switch and a first terminal of a capacitor, a second semiconductor switch to be coupled to a second terminal of the high voltage source, a second inductor to be coupled to the second semiconductor switch and a second terminal of the capacitor, and a diode coupled to the first semiconductor switch, the second semiconductor switch, the first inductor, and the second inductor, and coupled in parallel with the capacitor.