Series Switch Precharge Circuit for Common-Mode Voltage Interference
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Solution Overview
Problem
In photovoltaic power generation systems, the sudden change in voltage between switch components during the transition from a faulty to a functional state causes common-mode voltage interference, leading to peak currents that can disrupt the power signal and pose a risk to system operation.
Innovation Solution
Connecting two ends of one switch component in series to a passive component, such as a resistor, allows the high-voltage end to charge the low-voltage end, reducing the voltage difference over time, and ensuring that the second switch component can be turned on with minimal common-mode voltage interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two switch components are connected in series for safety regulation, then system reliability is improved, but common-mode voltage interference and peak current occur during switching transition
Solution Approach 1:
A resistor is introduced as an intermediary component connected in parallel with the first switch component. This resistor provides a controlled discharge path for the voltage difference during switching transitions, acting as a mediator that prevents harmful peak currents while maintaining the series switch configuration for reliability.
Solution Approach 2:
The resistor is pre-connected in parallel with the first switch component before switching operations occur. This pre-positioned resistor cushions the voltage difference that arises during switching transitions, preventing harmful effects before they can occur during the actual switching event.
2Reliability
If the second switch component is turned on after the first switch component, then safety requirements are met, but sudden voltage change causes peak current
Solution Approach 1:
The resistor serves as an intermediary that provides a controlled path for voltage equalization between the two switch components. During the transition period when the first switch is on and the second switch is off, the resistor limits the rate of voltage change and prevents harmful peak currents when the second switch is activated.
Solution Approach 2:
The resistor changes the electrical parameters (voltage and current distribution) during the switching transition period. By providing an alternative path for current flow, it modifies the voltage difference parameters between the two switch components, preventing sudden parameter changes that would cause peak currents.
3Reliability
If grounded class-Y capacitors are used for safety, then electrical safety is improved, but they form a path for peak current during voltage transitions
Solution Approach 1:
The resistor acts as an intermediary component that provides a preferred path for voltage equalization during switching transitions. This prevents the voltage difference from forcing current through the grounded class-Y capacitors, thereby protecting these safety components from harmful peak currents while maintaining their safety function.
Solution Approach 2:
The resistor provides preliminary protection by establishing a controlled discharge path before voltage transitions occur. This preliminary anti-action prevents the formation of harmful current paths through the class-Y capacitors by already having a safe voltage equalization route available during the transition period.
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 approach significantly reduces the impact of common-mode voltage on the power supply system, protecting the switch components and maintaining system stability by minimizing sudden voltage changes and peak currents.
Implementation Method 1
Connecting two ends of one switch component in series to a passive component, such as a resistor, allows the high-voltage end to charge the low-voltage end, reducing the voltage difference over time
Data Source
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AI summary
This application discloses a device, a method, and a system for resolving common-mode voltage interference. The device is applied to a power supply system, the power supply system includes a power converter and a switch mechanism, each phase of an output end of the power converter is connected to a downstream circuit by using the switch mechanism, the power converter is configured to perform electric energy conversion, the switch mechanism includes a first switch component and a second switch component that are connected in series, the device includes a controller and a passive component, two ends of the first switch component in at least one phase of the output end of the power converter are connected in parallel to the passive component, and the controller is configured to: control the second switch component to be turned on, and when a voltage difference between the two ends of the first switch component is less than a preset voltage, control the first switch component to be turned on. When the second switch component connected in series to the first switch component is turned on first, a high-voltage end charges a low-voltage end by using the passive component, to reduce the voltage difference between the two ends of the first switch component. After the voltage difference between the two ends of the first switch component is less than the preset voltage, the first switch component is turned on. In this case, a case in which there is a very large sudden change between voltages at the two ends of the first switch component due to closing of the first switch component does not occur, so that a common-mode current can be reduced, a power supply risk can be prevented in the power supply system, and the switch component is protected, thereby prolonging a service life of the switch component.