Power Conversion Device Switch Timing Synchronization
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Solution Overview
Problem
In DC common-busbar connections, independent switch control among inverters can lead to variations in operating times, causing short-circuit charge currents that may damage components, especially when inverters with different capacitances are connected, resulting in potential damage and degradation.
Innovation Solution
A power conversion device with parallel-connected power-supply circuit units, each comprising a converter, switch, resistor, capacitor, and control unit, where a voltage detection unit synchronizes switch operations across units to ensure consistent closing and opening times, minimizing variations in switch operation timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If independent switch control is used in each inverter, then device complexity is reduced and ease of operation is improved, but variations in operating time between switches occur causing short-circuit charge currents that damage components
Solution Approach 1:
The patent merges the control functions of multiple inverters into a master-slave architecture where one inverter acts as master and others as slaves. The master inverter centrally controls the switching operations of all slave inverters, ensuring synchronized switch operation times. This eliminates the timing variations that occur with independent control while maintaining operational simplicity through centralized management.
Solution Approach 2:
The patent implements feedback mechanisms where the master inverter monitors the operational status and timing of slave inverters, and adjusts control signals to synchronize switch operations. This feedback loop ensures that all switches operate at coordinated times, preventing short-circuit charge currents while maintaining ease of operation through automatic timing adjustment.
2Adaptability or versatility
If inverters with different capacitances are connected through DC common busbar, then system adaptability is improved, but short-circuit charge current causes serious damage to inverters with lower capacitance
Solution Approach 1:
The patent merges the control functions of multiple inverters into a master-slave architecture where one inverter acts as master and others as slaves. The master inverter centrally controls the switching operations of all slave inverters, ensuring synchronized switch operation times. This eliminates the timing variations that occur with independent control while maintaining operational simplicity through centralized management.
Solution Approach 2:
The patent implements preliminary synchronization of switch operation timings before power supply resumption. The control unit calculates and sets predetermined timing for each inverter's switches based on their capacitance values, ensuring that switches close in a coordinated sequence. This preliminary action prevents short-circuit charge currents by ensuring that switches are not closed at different times when voltage is restored.
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 effectively suppresses variations in switch operation times, preventing damage from short-circuit charge currents and enabling safe operation of inverters with different capacitances by coordinating switch control across units.
Implementation Method 1
a first converter to convert an AC voltage supplied from a power supply to a DC voltage
Implementation Method 2
a first capacitor to smooth a DC voltage supplied through the first circuit unit
Data Source
AI summary
A first control unit outputs a closing-operation command signal to a first switch at a timing calculated based on either a first closing time or a second closing time, whichever is later. The first closing time is a time required for the first switch to transition to a closed state after the first control unit detects a first detection signal indicating that a voltage detected by a voltage detection unit exceeds a predetermined threshold value. The second closing time is a time required for a second switch to transition to a closed state after the first detection signal is detected by a second control unit. The second control unit outputs a closing-operation command signal to the second switch at a timing calculated based on a first time. This can suppress variations in an operating time between a plurality of switches.