Power Conversion Device Intermediate Capacitor Charging
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Solution Overview
Problem
Conventional DC/DC power conversion devices require an initial charging circuit, increasing the number of components and complicating the circuit configuration.
Innovation Solution
A power conversion device configuration that includes a boosting unit with specific switching elements and reverse-current blocking elements, an intermediate capacitor, a smoothing capacitor, and a control unit that controls the switching elements to charge the capacitors without the need for an initial charging circuit, using a reactor between the step-down and boosting units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an initial charging circuit is added to charge the intermediate capacitor before operation, then the switching elements are protected from overvoltage, but the number of components increases and the circuit configuration becomes complicated
Solution Approach 1:
The power conversion device charges the intermediate capacitor automatically during its normal operation cycle. The control unit manages the charging process by controlling the switching elements, eliminating the need for a separate initial charging circuit. The system serves itself by utilizing its own operational mechanisms to perform the charging function that previously required dedicated external circuitry.
2Power
If the voltage difference between intermediate capacitor and smoothing capacitor is great, then the boosting function is effective, but the elements are subjected to excessive voltage and may be broken
Solution Approach 1:
The control unit dynamically adjusts the charging process of the intermediate capacitor during normal operation, rather than requiring a static pre-charging step. By controlling the switching elements timing and duration, the system dynamically manages voltage distribution between capacitors, ensuring optimal boosting performance while preventing excessive voltage stress on components throughout the operational cycle.
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 eliminates the need for an initial charging circuit, simplifying the configuration and protecting the switching elements from excessive voltage and current, allowing for efficient DC voltage boosting and stepping down without overloading components.
Implementation Method 1
a power conversion device that boosts/steps down DC voltage by controlling the amounts of accumulation and release of magnetic energy of a reactor through ON/OFF operations of switching elements
Implementation Method 2
DC voltage is boosted/stepped down using magnetic energy of the reactor and electrostatic energy of the intermediate capacitor in combination
Implementation Method 3
a smoothing capacitor which is connected in parallel to the boosting unit and smooths the DC voltage boosted by the boosting unit
Data Source
AI summary
The power conversion device includes: a boosting unit for boosting DC voltage, the boosting unit including a second switching element, a third switching element, a second reverse-current blocking element, and a third reverse-current blocking element which are connected in series, the boosting unit including an intermediate capacitor connected between a connection point between the second reverse-current blocking element and the third reverse-current blocking element, and a connection point between the third switching element and the second switching element; a smoothing capacitor which is connected in parallel to the boosting unit and smooths the DC voltage boosted by the boosting unit; and a control unit for turning on the third switching element so that the intermediate capacitor is charged to charge completion voltage of the intermediate capacitor.