Boost Converter Control for Line Current Harmonic Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power supplies face inefficiencies due to input current harmonics, which lead to increased power dissipation and higher costs and sizes of electrical components, primarily caused by distortions in the current and voltage waveforms resulting from electromagnetic interference.
Innovation Solution
A boost converter control technique that varies the on-time and off-time of a switching cycle to shape the input current waveform, making it proportional to the input voltage waveform by maintaining a constant volt-second balance, thereby reducing line current harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a boost converter is used to transform the current waveform to its ideal sinusoidal shape, then power quality is improved, but device complexity increases
Solution Approach 1:
The patent changes the switching frequency parameter dynamically based on the input voltage waveform. By adjusting the switching frequency to track the line frequency and its harmonics, the boost converter achieves better power quality without requiring additional complex circuitry. This parameter adaptation allows the existing converter topology to adapt to varying input conditions and reduce harmonic distortion.
2Reliability
If switching frequency is varied to reduce harmonics, then power quality is improved, but control complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the switching frequency is continuously adjusted based on detection of the input voltage waveform characteristics. The controller monitors the line frequency and its variations, then adapts the switching frequency accordingly to maintain optimal power factor and minimize harmonics. This closed-loop control enables automatic adaptation without requiring complex manual tuning or additional hardware.
Data Source
AI summary
A method and apparatus for controlling a power converter. In one aspect, a controller for use in a power converter includes a first calculator coupled to determine an end of an on time of a power switch of the power converter by integrating an input current to output an on time signal representative of the end of the on time of the power switch. The controller also includes a second calculator coupled to determine an end of an off time of the power switch by integrating a difference between an input voltage and an output voltage to output an off time signal representative of the end of the off time of the power switch.