Bidirectional Switch Inverter Control for Zero-Voltage Switching
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Solution Overview
Problem
Existing power conversion circuits with LC resonance circuits suffer from significant switching losses in inverter circuits.
Innovation Solution
A power conversion device incorporating a bidirectional switch with a shunt capacitor and choke inductor, controlled by a control unit to adjust the on-duty of the switching operation based on input voltage polarity, enabling Zero Voltage Switching (ZVS) to reduce switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional inverter circuit with LC resonance circuit is used, then AC power can be converted to high-frequency AC current, but switching loss increases significantly
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control unit dynamically adjusts the switching frequency of the bidirectional switch based on real-time detection of input voltage polarity and magnitude. This dynamic adjustment ensures that the circuit operates at optimal frequencies for ZVS conditions, thereby minimizing switching losses while maintaining efficient power conversion across varying input conditions
Solution Approach 2:
The patent implements parameter changes by modifying the switching frequency parameter in response to changing input conditions. Specifically, the control unit changes the switching frequency based on the detected input voltage polarity (positive or negative) and magnitude. This parameter adaptation allows the circuit to maintain Zero Voltage Switching conditions across different operating points, effectively reducing switching losses while preserving power conversion efficiency
2Loss of energy
If switching frequency is changed to achieve ZVS, then switching loss is reduced, but control complexity increases
Solution Approach 1:
The patent employs feedback by using a control unit that continuously detects the input voltage polarity and magnitude, then uses this information to adjust the switching frequency. This closed-loop feedback mechanism ensures that the switching frequency is automatically optimized to maintain ZVS conditions without requiring complex external control systems. The feedback approach simplifies the overall control complexity while achieving effective switching loss reduction
Solution Approach 2:
The circuit implements self-service through its ability to automatically adjust switching frequency based on detected input conditions without external intervention. The control unit autonomously determines the appropriate switching frequency by detecting input voltage polarity and magnitude, then independently adjusts the switching parameters to maintain optimal ZVS operation. This self-adjusting capability reduces the need for complex external control systems and simplifies the overall device architecture
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 reduces switching losses in the inverter circuit, allowing for high-frequency AC current conversion with high efficiency and low total harmonic distortion.
Implementation Method 1
a power conversion circuit in which a class-E inverter circuit having an LC resonance circuit converts AC input power into a high-frequency AC current
Data Source
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AI summary
In a power conversion device (10), a bidirectional switch (21) of an inverter circuit (20) including an LC resonance circuit (22) switches a direction and an on/off state of a current flowing between a pair of input terminals (IN1, IN2). The inverter circuit (20) generates a high-frequency AC current from AC power input to the pair of input terminals (IN1, IN2). The inverter circuit (20) includes a shunt capacitor (C2) that is connected between the pair of input terminals (IN1, IN2) in parallel to the bidirectional switch (21), and a choke inductor that is connected between the bidirectional switch (21) and at least one input terminal of the pair of input terminals (IN1, IN2). A control unit (40) changes an on-duty of a switching operation of the bidirectional switch (21) according to a polarity of a voltage of the AC power input to the pair of input terminals (IN1, IN2).