PWM-Controlled Power Supply for Zero-Current Switching
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Solution Overview
Problem
Conventional power supply devices experience increased switching loss and reduced efficiency due to non-ideal output current reduction when the output diode switches from a turned-on to a turned-off state, leading to inefficiencies in power conversion.
Innovation Solution
A power supply device incorporating a switch circuit, transformer, capacitor, and PWM IC that generates switching voltages and adjusts switching frequency and duty cycle based on output current to achieve Zero-Current Switching (ZCS) operation through a self-calibration process, reducing switching loss and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional output diode switching is used, then the power supply device can operate, but switching loss increases and efficiency decreases
Solution Approach 1:
The patent implements dynamic control of the output diode switching process by using a resonant circuit to actively manage the current waveform. The switching frequency and timing are dynamically adjusted to ensure current reaches zero before the diode turns off, converting the static switching problem into a dynamically controlled resonant process that eliminates switching losses.
Solution Approach 2:
The patent changes the operating parameters of the switching circuit by introducing a resonant frequency component. By adjusting the LC resonant circuit parameters (inductance and capacitance values), the system achieves zero-current switching conditions, fundamentally changing the switching behavior from hard switching to soft switching operation.
2Loss of energy
If output current is not reduced to 0 during switching, then the power supply can maintain continuous power delivery, but switching loss increases
Solution Approach 1:
The patent applies preliminary action by using the resonant circuit to pre-reduce the output current to zero before the output diode is instructed to turn off. This preliminary current reduction ensures that when the diode switching occurs, the current is already at zero level, eliminating switching losses while maintaining power delivery continuity through the controlled resonant process.
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 loss and improves overall efficiency by ensuring ideal ZCS operation, making it suitable for various electronic devices such as desktop and notebook computers.
Implementation Method 1
The transformer includes a main coil, a first secondary coil, and a second secondary coil. The main coil receives the switching voltage through the leakage inductor.
Implementation Method 2
A leakage inductor and a magnetizing inductor are built into the transformer.
Implementation Method 3
The PWM IC generates the first PWM voltage and the second PWM voltage. The PWM IC selectively adjusts the switching frequency and the duty cycle of the first PWM voltage according to the output current.
Implementation Method 4
The first capacitor is coupled to the magnetizing inductor.
Data Source
AI summary
A power supply device with a high efficiency includes a switch circuit, a transformer, a first capacitor, an output stage circuit, and a PWM (Pulse Width Modulation) IC (Integrated Circuit). The switch circuit generates a switching voltage according to an input voltage, a first PWM voltage, and a second PWM voltage. The transformer includes a main coil, a first secondary coil, and a second secondary coil. A leakage inductor and a magnetizing inductor are built into the transformer. The main coil receives the switching voltage through the leakage inductor. The output stage circuit is coupled to the first secondary coil and the second secondary coil, and is configured to generate an output voltage and an output current. The PWM IC selectively adjusts the switching frequency and duty cycle of the first PWM voltage according to the output current.