Digital Control Device for Switching Power Supply
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Solution Overview
Problem
Switching power supplies with capacitance filters suffer from low power factor and high total harmonic distortion due to quasi-sinusoidal current absorption, leading to increased energy dissipation and inefficient energy use, as the current peaks and rms values are higher than sinusoidal absorption, causing distortion in the supply voltage and increased energy dissipation.
Innovation Solution
A digital control device for a switching power supply that adjusts the closing and opening time periods of a switch connected to an inductor, using a counter and comparator to control the switch based on input signals, ensuring a regulated output voltage and minimizing peak current distortion, thereby improving power factor and reducing total harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a capacitance filter is used in the switching power supply, then the output voltage is stabilized, but the power factor decreases and total harmonic distortion increases
Solution Approach 1:
The patent implements a control device that continuously monitors the output voltage and adjusts the switch closing and opening time periods based on feedback signals. This feedback mechanism allows the system to maintain stable output voltage while dynamically optimizing the switching parameters to improve power factor and reduce harmonic distortion.
Solution Approach 2:
The patent transitions from fixed switching parameters to dynamic adjustment of switch closing and opening time periods. The control device modifies the switching duty cycle in real-time based on load conditions and output voltage requirements, enabling the system to maintain high efficiency and low distortion across varying operating conditions.
2Use of energy by moving object
If the switch closing and opening time periods are extended, then the energy transfer efficiency improves, but the peak current increases and harmonic distortion worsens
Solution Approach 1:
The patent systematically adjusts switching parameters including closing time period, opening time period, and duty cycle to optimize performance. By changing these parameters dynamically rather than using fixed values, the system achieves high energy transfer efficiency while keeping peak currents and harmonic distortion within acceptable limits.
Solution Approach 2:
The control device prevents the switch from remaining closed for excessively long periods by implementing maximum duty cycle limits and minimum off-time requirements. This partial action approach ensures that energy transfer is optimized without allowing the switch conduction time to become excessive, which would cause peak current and distortion problems.
Data Source
AI summary
A control device controls a switching converter. The converter has an input alternating supply voltage, a regulated direct voltage on the output terminal, and a switch connected to an inductor. The control device controls the closing and opening time period of said switch for each cycle and receives a first input signal representative of the current flowing through one element of the converter. The control device comprises a counter configured to count a time period, a comparator configured to compare said first input signal with a second signal, digital control block configured to control the closing and opening of said switch and to activate said counter to start the counting of said time period when the said first input signal crosses said second signal, with said switch being closed. The digital control block is configured to open the switch when the counter finishes the counting of said time period.