Power Converter Capacitor Discharge Using a Ground Resistor
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Solution Overview
Problem
The existing power conversion systems suffer from increased losses and costs due to the use of high-capacity discharge resistors, which also occupy more space, as they are constantly subjected to high direct-current voltage during power supply.
Innovation Solution
Incorporating a ground resistor and a discharge switch in the power conversion system, allowing the ground resistor to function as the discharge resistor, reducing the need for a separate discharge resistor and minimizing the capacity of the ground resistor, along with additional safety features like a second ground resistor and controlled switch operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate discharge resistor is provided between the positive electrode direct-current line and the negative electrode direct-current line, then the capacitor can be discharged, but the loss and cost of the power conversion system are increased due to the high capacity required
Solution Approach 1:
The patent merges the discharge resistor function with the ground resistor by connecting the ground resistor between the negative electrode direct-current line and the ground line. This eliminates the need for a separate discharge resistor, reducing both cost and energy loss while maintaining the discharge function through the ground resistor when the discharge switch is turned on.
Solution Approach 2:
The ground resistor is given dual functionality: it serves both as a ground resistor for grounding the negative electrode direct-current line and as a discharge resistor for discharging the capacitor. This multi-functionality reduces the total number of components and eliminates the need for a high-capacity separate discharge resistor.
2Reliability
If the capacity of the discharge resistor is increased to handle constant high direct-current voltage, then the discharge function is improved, but the cost and installation space are increased
Solution Approach 1:
By combining the ground resistor and discharge resistor functions into a single component, the patent eliminates the need for a high-capacity separate discharge resistor. The ground resistor handles discharge duties during maintenance modes, allowing for reduced capacity and smaller physical footprint.
Solution Approach 2:
The discharge switch is turned on only during maintenance modes (when disconnect switches are open) and kept off during normal power conversion operations. This periodic activation reduces the overall stress and capacity requirements on the ground resistor, allowing for a more compact design.
3Ease of manufacture
If multiple small-capacity discharge resistors are connected in series, then the cost per resistor is reduced, but the number of components and installation space are increased
Solution Approach 1:
The patent eliminates the need for multiple series-connected discharge resistors by using a single ground resistor with dual functionality. This simplifies the circuit configuration, reduces the number of components, and lowers overall system complexity while maintaining cost-effectiveness.
Solution Approach 2:
The ground resistor serves both grounding and discharge functions, eliminating the need for multiple specialized discharge resistors. This multi-functional approach reduces component count and simplifies the overall system architecture.
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 reduces power losses and costs, while ensuring safe discharging and space efficiency by eliminating the need for a separate discharge resistor and minimizing the capacity of the ground resistor.
Implementation Method 1
a capacitor 14 provided between the positive electrode direct-current line 12 and the negative electrode direct-current line 13
Implementation Method 2
when the discharge switch 16a is turned on, the charges stored in the capacitor 14 are discharged by the first ground resistor 15a
Data Source
AI summary
According to the present disclosure, there is provided an inexpensive power conversion system that can achieve loss reduction and space saving. The power conversion system includes: a power converter configured to convert direct-current power input from a direct-current power supply, into alternating-current power or direct-current power; a capacitor provided between a positive electrode direct-current line and a negative electrode direct-current line connected to input terminals of the power converter; a ground line provided with a first ground resistor and configured to connect the negative electrode direct-current line and a ground potential; a discharge line configured to connect the positive electrode direct-current line and the ground line on the ground potential side of the first ground resistor; and a discharge switch provided in the discharge line and configured to be turned on to discharge residual charges of the capacitor.