Direct Power Converter Amplitude Modulation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing direct power converters have a limited input amplitude modulation factor, which restricts the efficiency and output voltage of the converter.
Innovation Solution
The method involves adjusting the rectifying and discharge duties in the direct power converter to increase the virtual DC link voltage, allowing for a higher input amplitude modulation factor by optimizing the rectifying duty in the second period and discharge duty in the first period, and controlling the booster circuit to manage the reactor current effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rectifying duty and discharge duty are optimized to increase the virtual DC link voltage, then the input amplitude modulation factor increases, but the device complexity increases due to additional control requirements
Solution Approach 1:
The patent applies dynamic control by making the rectifying duty and discharge duty variable rather than fixed. The controller dynamically adjusts these duty ratios based on operating conditions to optimize the virtual DC link voltage and maximize the input amplitude modulation factor, resolving the contradiction between performance improvement and control complexity
Solution Approach 2:
The patent changes key operational parameters (rectifying duty ratio and discharge duty ratio) to transform the system performance. By varying these parameters, the virtual DC link voltage is optimized, which directly increases the input amplitude modulation factor while maintaining manageable control complexity through parameter-based control strategies
2Device complexity
If the reactor capacity is reduced to decrease device size and cost, then the device complexity decreases, but the ability to manage current and maintain voltage stability deteriorates
Solution Approach 1:
The patent implements feedback control mechanisms where the controller monitors the reactor current and virtual DC link voltage, then adjusts the rectifying and discharge duties accordingly. This feedback loop compensates for the reduced reactor capacity, maintaining current management capability and voltage stability despite using a smaller, less complex reactor
Solution Approach 2:
The patent introduces the virtual DC link voltage as an intermediary controlled parameter that mediates between the reactor current and the inverter input. By controlling this intermediary parameter through duty ratio adjustments, the system maintains stability and current management capability even with reduced reactor capacity
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 approach enhances the output voltage of the inverter, increases the input amplitude modulation factor, and reduces distortion in the input current, while also allowing for a smaller reactor capacity, leading to size and cost reductions in the converter.
Implementation Method 1
A diode rectifier performs full-wave rectification on single-phase AC voltage
Implementation Method 2
An inverter converts a DC voltage to an AC voltage and outputs the AC voltage
Implementation Method 3
The buffer circuit includes connection in series between a capacitor and a switch
Implementation Method 4
The step up circuit is constituted of a step-up chopper and includes a switch, the reactor and a diode
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present invention is directed to a single-phase to three-phase direct converter that increases in an input amplitude modulation factor. In a first period (T1) when a cosine value (cos(2ωt)) is positive that is a cosine value of a value twice a phase angle (ωt) determined while an AC waveform output from a single-phase AC power source is regarded as a sine value of the phase angle (ωt), a discharge duty (dc) for making a first switch conducting is set to be higher than a first value determined by dividing the product of an amplitude of an AC voltage of the single-phase AC power source and the cosine value by the product of an across voltage of a capacitor and 2. In addition to or alternatively to this, in a second period (T2) when the cosine value is negative, a rectifying duty (drec) for making a diode rectifier conducting is set to be higher than a second value that is the reciprocal of the product of the absolute value of the sine value and 2.