Power Converter Sine-Wave Current Control for Harmonic Suppression
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Solution Overview
Problem
Conventional power-factor improving circuits face inefficiencies and increased reactor iron loss due to limited control patterns of the short-circuit element, particularly in low-load areas, leading to significant waveform distortion and harmonic components, which result in decreased AC/DC conversion efficiency and increased circuit size and cost.
Innovation Solution
A power converting device with a rectifying circuit, a short-circuit unit, and a control unit that generates multiple sine-wave-shaped switching pulses to control the short-circuit unit during the alternating-current power supply's half cycle, maintaining the power supply current within a sine-wave-shaped control range to suppress peaks and enhance boost performance while meeting harmonic standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional partial switching control is used for the short-circuit element, then the direct-current output voltage range is enlarged, but the power factor improvement is insufficient and harmonic components increase in low-load areas
Solution Approach 1:
The patent applies dynamics by transitioning from fixed open-loop switching control to dynamic feedback control. The control unit continuously adjusts the short-circuit element's on/off timing based on real-time detection of power supply current, enabling the system to adapt to varying load conditions and maintain optimal power factor across the entire load range, particularly improving low-load performance.
Solution Approach 2:
The patent implements feedback control by detecting the power supply current and using this information to adjust the short-circuit element's switching timing. This closed-loop control ensures that the power supply current maintains a sinusoidal waveform with minimal harmonics, resolving the contradiction between voltage range enlargement and harmonic suppression.
2Loss of energy
If the short-circuit element is not operated in low-load area, then excessive boosting of direct-current output voltage is avoided, but power factor improvement is not performed and reactor iron loss increases
Solution Approach 1:
The feedback control mechanism detects power supply current and adjusts the short-circuit element's switching in low-load areas to maintain sinusoidal current waveform. This enables power factor improvement across the entire load range, reducing reactor iron loss by preventing excessive waveform distortion even when load is low.
Solution Approach 2:
The patent changes the operational parameters of the short-circuit element by adjusting its switching timing and duration based on load conditions. In low-load areas, the control unit modifies the switching parameters to maintain optimal power factor and minimize harmonic components, thereby reducing reactor iron loss.
3Power
If conventional open-loop control is used, then control simplicity is maintained, but the boosting capability is limited and high-load operation becomes unstable
Solution Approach 1:
The patent introduces feedback control that detects power supply current and automatically adjusts the short-circuit element's switching timing. This feedback mechanism enhances boosting capability and stabilizes high-load operation without requiring complex manual control patterns, as the system self-adjusts based on real-time conditions.
Solution Approach 2:
The control system performs self-service by automatically detecting power supply current and adjusting its own switching parameters. This self-regulating capability eliminates the need for complex external control patterns while enhancing boosting capability and stabilizing operation across the entire load range.
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
This solution achieves high boost performance and meets harmonic standards across the entire load operation area, improving efficiency and reducing reactor size and cost by suppressing peak currents and waveform distortion.
Implementation Method 1
a rectifying circuit that converts alternating-current power from an alternating-current power supply into direct-current power
Implementation Method 2
a reactor 2, the rectifying circuit 3
Data Source
AI summary
A power converting device includes: a rectifying circuit connected to an alternating-current power supply for converting alternating-current power from the alternating-current power supply into direct-current power; a short-circuit unit constituted by a diode bridge and a short-circuit element connected to opposite output ends of the diode bridge for short-circuiting the alternating-current power supply via a reactor; and a control unit that generates plural drive signals to control the short-circuit unit during a half cycle of the alternating-current power supply. The control unit generates a sine-wave-shaped current control range that is a target control range of power supply current of the alternating-current power supply, and maintains values of the power supply current of the alternating-current power supply within the current control range.