Switch Sequencing With Passive Precharge for Common-Mode Voltage
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Solution Overview
Problem
In photovoltaic power generation systems, the sudden change in voltage between switch components during the switching process leads to significant common-mode voltage interference, causing peak currents that can disrupt power signals and pose a risk to system operation.
Innovation Solution
A device and method that connect the ends of one switch component in parallel to a passive component, allowing the high-voltage end to charge the low-voltage end before the switch is turned on, thereby reducing the voltage difference and minimizing common-mode voltage interference, using a controller to sequence the switch components and passive components to ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two switch components are connected in series for safety regulation, then reliability is improved, but common-mode voltage interference increases when switching
Solution Approach 1:
The patent applies preliminary action by connecting a passive component (resistor or capacitor) in parallel with one of the switch components before switching occurs. This passive component pre-charges or pre-discharges to reduce the voltage difference across the switch component before it closes, thereby preventing sudden voltage changes and common-mode voltage interference while maintaining the series switching safety configuration
Solution Approach 2:
The patent uses a passive component as an intermediary element connected in parallel with one switch component. This intermediary component acts as a buffer that mediates the voltage transition, gradually equalizing the voltage difference before the switch closes, thus eliminating the harmful common-mode voltage spike while allowing the series switching arrangement to remain for safety
2Speed
If switch components are turned on without voltage equalization, then switching speed is improved, but peak current increases causing interference
Solution Approach 1:
The patent implements preliminary action by using a passive component connected in parallel with one switch component to pre-equalize the voltage difference before switching. This preparation step occurs rapidly and enables the main switch to close with minimal voltage differential, achieving both fast switching speed and minimal peak current generation
3Object-affected harmful factors
If voltage difference is reduced before switching, then common-mode voltage interference is reduced, but additional components are required
Solution Approach 1:
The patent employs a simple, inexpensive passive component (resistor or capacitor) that can be easily integrated into the circuit. This disposable-like component serves its purpose of reducing common-mode voltage interference and can be a standard off-the-shelf part, minimizing the impact on device complexity despite the added component
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 reduces the voltage difference between switch components, minimizing the impact on the power supply system and extending the service life of the switch components by preventing sudden voltage changes and associated peak currents.
Implementation Method 1
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... When a switch component that is not connected in parallel to the passive component is turned on, a high-voltage end charges a low-voltage end by using the passive component
Data Source
AI summary
A device for resolving common-mode voltage interference is applied to a power supply system including 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 switch mechanism includes a first switch and a second switch. The device includes a controller and a passive component. Two ends of the first switch in at least one phase of the output end of the power converter are connected in parallel to the passive component, and the controller controls the second switch to be turned on, and when a voltage difference between the two ends of the first switch is less than a preset voltage, controls the first switch to be turned on. In this manner, the switch mechanism is protected, thereby prolonging a service life of the switch mechanism.