Power Conversion Device Current Detection Circuit
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Solution Overview
Problem
Existing power conversion devices face challenges in achieving both high efficiency and low cost for current detection, as methods either require full-wave rectification, increasing costs, or use expensive current transformers, failing to provide both high efficiency and inexpensive control simultaneously.
Innovation Solution
A power conversion device with a control unit that generates burst pulse signals to manage switches and diodes in a closed loop configuration, allowing for sinusoidal current synchronization with AC power supply phases, using inexpensive components for current detection without the need for expensive transformers or full-wave rectification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an insulation current transformer is used for current detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the current detection function from the main power conversion circuit by using a separate detection circuit that measures voltage across a known impedance. This separation allows accurate current measurement without requiring complex current transformers, as the detection is performed on a scaled-down voltage signal rather than the full current directly.
Solution Approach 2:
The patent introduces an intermediary detection circuit that converts current measurement into voltage measurement across a known impedance element. This intermediary approach allows the microcontroller to measure current indirectly through voltage, simplifying the overall system while maintaining measurement accuracy through computational processing.
2Device complexity
If a resistor with low resistance is inserted into current path for detection, then device complexity is reduced, but use of energy increases due to full-wave rectification requirement
Solution Approach 1:
The patent implements dynamic control of the detection circuit by selectively activating different detection paths based on the polarity of the AC input voltage. The microcontroller dynamically adjusts which switches are closed and which impedance elements are used for detection, allowing accurate current measurement during both positive and negative half-cycles without requiring continuous full-wave rectification.
Solution Approach 2:
The patent changes the operational parameters of the detection circuit based on input voltage polarity. During positive half-cycles, one detection path is activated with specific switches closed; during negative half-cycles, different switches are closed and different impedance elements are used. This parameter change approach eliminates the need for continuous full-wave rectification while maintaining detection accuracy.
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 efficient power conversion while minimizing costs by accurately detecting and controlling circuit currents using inexpensive components, achieving miniaturization and weight reduction while maintaining high efficiency.
Implementation Method 1
The power conversion device detects a circuit current which flows from an AC power supply to a circuit to generate a control signal
Data Source
AI summary
According to one embodiment, a power conversion device includes a first switch serially connected to a second switch, a first diode serially connected to a second diode, the first switch and the first diode connected to the second switch and the second diode, an AC power supply and an inductor serially connected to a connection point between the first switch and the second switch and a connection point between the first diode and the second diode, a capacitor serially connected to ends of the first diode and the second diode connected, and a potential difference between the ends of the capacitor is used as an output voltage. The control unit supplies a pulse signal to the first switch and the second switch to provide a sinusoidal current through the AC power supply, based on a detected power supply voltage, a detected circuit current, and a detected capacitor voltage.