Non-Isolated Resonant DCDC Control for Sinusoidal Current Conversion
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Solution Overview
Problem
Existing non-isolated DCDC buck-boost converters suffer from high losses due to the triangular current waveform, which results in significant conduction losses and high-order harmonic wave losses.
Innovation Solution
A non-isolated DCDC resonant conversion control circuit is introduced, featuring an input interface, switching transistors, an inductor, a capacitor, and an output interface. The inductor and capacitor are connected in series, resulting in a sine waveform current through the inductor, which reduces conduction losses. The phase shift angle and switching frequency are adjustable to optimize the conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional buck or boost critical continuous mode is used, then a switching transistor can implement zero voltage switching (ZVS) on, but an inductance current is a triangular wave, a peak current is relatively large, and a turn-off current of the switching transistor is relatively large
Solution Approach 1:
The patent changes the waveform parameter from triangular to sinusoidal by introducing a resonant capacitor and operating in resonant continuous conduction mode (RCCM). This parameter change reduces the waveform coefficient from that of a triangular wave to that of a sine wave, thereby reducing conduction losses while maintaining soft switching capability.
Solution Approach 2:
The patent utilizes resonant vibration by introducing a capacitor to form an LC resonant circuit. The inductor current oscillates in a sinusoidal manner at the resonant frequency, which reduces the peak current and turn-off current compared to triangular wave operation, thereby reducing conduction losses.
2Ease of manufacture
If a triangular wave current is used in the inductor, then the circuit can be controlled in a conventional buck or boost mode, but a waveform coefficient of the triangular wave is greater than a waveform coefficient of a sine wave, and a triangular wave has a larger conduction loss than the sine wave when same power is transmitted
Solution Approach 1:
The patent changes the current waveform parameter from triangular to sinusoidal by operating in resonant continuous conduction mode with an LC tank circuit. This changes the waveform coefficient, which directly reduces conduction losses when transmitting the same power, while the control remains relatively simple through phase shift modulation.
3Productivity
If a triangular wave is used in the inductor, then the circuit can operate in conventional mode, but high content of high-order harmonic waves in the triangular wave increases a high-order harmonic wave loss
Solution Approach 1:
The patent utilizes resonant vibration to generate a sinusoidal current waveform in the inductor, which inherently contains fewer high-order harmonic components compared to a triangular wave. This reduces high-order harmonic wave losses and improves overall conversion efficiency.
Solution Approach 2:
By changing the operating mode from conventional critical continuous mode to resonant continuous conduction mode, the patent transforms the current waveform from triangular to sinusoidal. This parameter change significantly reduces the high-order harmonic content, thereby reducing high-order harmonic wave losses.
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 proposed circuit significantly reduces circuit losses by utilizing a sine waveform current, while also enabling wide-range DCDC resonant conversion through adjustable phase shift angle and switching frequency, thereby improving efficiency and flexibility.
Implementation Method 1
the inductor and the capacitor are in a resonant working state
Data Source
AI summary
According to a non-isolated DCDC resonant conversion control circuit provided in embodiments of this application, an inductor and a capacitor that are resonant are connected in series, so that a current flowing through the inductor is a sine waveform. A waveform coefficient of the sine wave is small, and a conduction loss of the sine wave is low. Therefore, the circuit provided in embodiments of this application can significantly reduce a circuit loss. According to the non-isolated DCDC resonant conversion control method provided in embodiments of this application, not only a phase shift angle can be adjusted to enable a switching transistor to implement zero voltage switching (ZVS) on, but switching frequency can also be adjusted. Therefore, ranges in which a voltage and power of an output interface can be adjusted are large, so that non-isolated wide-range DCDC resonant conversion is implemented.