Power Converter Discharge Loop for Common Mode Voltage Grounding
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Solution Overview
Problem
Photovoltaic power generation systems face challenges in rapidly discharging common mode voltages to ground at the input terminal of a boost circuit to within a safe voltage, especially during maintenance or emergencies, due to high initial voltages and varying distributed capacitances, which hinder compliance with discharge voltage requirements.
Innovation Solution
A power converter with a bridge circuit and switching circuit, including controllable switches, forms a discharge loop to rapidly discharge common mode voltages to ground by short-circuiting the positive and negative input terminals of the boost circuit, controlled by a controller to ensure voltages meet safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optimizer or shutdown device enters safe mode to cut off input voltage, then the input voltage is controlled within safe limits, but the common mode voltage to ground remains much higher than safe voltage and cannot meet discharge voltage requirement
Solution Approach 1:
The patent introduces a bridge circuit as an intermediary component between the DC power supply and ground. This bridge circuit, combined with switching circuitry, creates a discharge loop that provides a controlled path for common mode voltage to discharge to ground, thereby mediating the harmful high voltage situation while maintaining the safe mode input voltage cutoff
2Speed
If traditional discharge methods are used without bridge circuit, then device complexity is lower, but discharge speed is insufficient to meet the requirement of dropping to 30V within 30 seconds
Solution Approach 1:
The patent employs dynamic switching control where the switching circuit can be activated or deactivated based on operational conditions. The controller dynamically manages the discharge loop formation, enabling rapid discharge when needed (meeting the 30V within 30 seconds requirement) while allowing the system to operate in a simpler state during normal operation, thus balancing speed requirements with device complexity
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
The solution enables rapid discharge of common mode voltages to within safe limits, meeting discharge voltage requirements, such as dropping to 30V within 30 seconds, by forming discharge loops through the bridge and switching circuits.
Implementation Method 1
the plurality of controllable switches to be switched on or switched off to form a discharge loop by the boost circuit, the bridge circuit, and the switching circuit, for discharging a common mode voltage to ground
Data Source
AI summary
Provided are a power converter, a method for controlling a power converter, and a power system. The power converter includes a boost circuit, an inverter circuit, a bridge circuit, a switching circuit, and a controller. The boost circuit is connected to a direct current power supply and the inverter circuit and the bridge circuit. The switching circuit is connected to the bridge circuit and ground. The switching circuit at least includes a plurality of controllable switches. The controller is configured to control, subsequent to the direct current power supply entering an off state, the plurality of controllable switches to be switched on or switched off to form a discharge loop by the boost circuit, the bridge circuit, and the switching circuit, for discharging a common mode voltage to ground at the input terminal of the boost circuit to be within a safe voltage.