Multi Switch Inverter APW Architecture Harmonic Reduction
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Solution Overview
Problem
Existing AC generator/inverter systems face challenges in reducing harmonics and maintaining zero voltage offset, which affects the efficiency and cost-effectiveness of AC power generation.
Innovation Solution
The implementation of a DC to AC converter-inverter with an amplitude pulse width (APW) architecture using a stepped DC voltage energy source, comprising semiconductor switches and a bridge circuit with Schottky diodes, to generate a multi-level stepped voltage waveform with modulated width, reducing harmonic distortion and eliminating voltage offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional solid state inverter solutions are used, then high efficiency and low cost are achieved, but harmonic distortion increases and voltage offset cannot be maintained at zero
Solution Approach 1:
The inverter divides the DC voltage into multiple discrete levels using series-connected battery strings (e.g., four 12V batteries creating five voltage levels: 0V, 12V, 24V, 36V, 48V). Each battery string segment can be independently switched to create a multi-level stepped voltage waveform, segmenting the voltage generation into manageable discrete steps that approximate a sine wave while reducing harmonics.
Solution Approach 2:
The system dynamically adjusts the width and amplitude of voltage steps in real-time using controllable semiconductor switches (MOSFETs/IGBTs) to modulate the multi-level waveform. The pulse width modulation dynamically varies the duration each voltage level is applied, enabling the stepped waveform to track the desired sine wave output and maintain zero voltage offset while minimizing harmonics.
2Object-generated harmful factors
If multi-level stepped voltage waveform with modulated width is generated, then harmonic distortion is reduced and voltage offset is eliminated, but device complexity increases
Solution Approach 1:
The bridge circuit serves multiple functions simultaneously: it switches polarity of the applied voltage, selects specific battery string combinations to create different voltage levels, modulates pulse width for harmonic reduction, and maintains zero voltage offset. This multi-functionality reduces the need for separate dedicated circuits for each function, managing complexity through integrated design.
Solution Approach 2:
The system changes key parameters of the voltage waveform (amplitude, pulse width, voltage levels) dynamically through controlled switching. By varying these parameters in a coordinated manner, the inverter generates a multi-level stepped waveform that approximates a sine wave, reducing harmonic distortion without requiring additional hardware beyond the switching devices and battery configuration.
3Loss of energy
If Schottky diodes are added to prevent reverse current flow and reduce switching losses, then conversion efficiency improves, but device complexity and cost increase
Solution Approach 1:
Schottky diodes are inserted as intermediary components between the semiconductor switches and the bridge circuit. These diodes act as one-way valves for current flow, preventing reverse current from damaging the switches and reducing switching losses by providing a low-forward-voltage-drop path. The Schottky diode's unique property of allowing current to flow easily in one direction while blocking reverse current makes it an effective intermediary that protects the switching devices and improves efficiency.
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 enhances the efficiency and reduces costs by generating high-quality AC power with minimized harmonic distortion and zero voltage offset, supporting integration of renewable energy and real-time load balancing in a Personal Power Plant system.
Implementation Method 1
a controller configured to generate a predetermined switching sequence to be applied to the plurality of semiconductor switches, wherein the controller is configured to sequentially connect and disconnect the MOS-FETs of the plurality of semiconductor switches to apply a multi-level stepped voltage waveform with a modulation of a selected step thereof
Implementation Method 2
a plurality of Schottky diodes to prevent backward current flow, wherein an anode of each Schottky diode is electrically coupled to a corresponding semiconductor switch of the plurality of semiconductor switches and a cathode of each Schottky diode is electrically coupled to the bridge circuit
Implementation Method 3
a bridge circuit, wherein the bridge circuit is electrically connected to the plurality of semiconductor switches and configured to switch a polarity of a voltage applied to a load coupled thereto
Implementation Method 4
the inverter may further comprise a harmonic filter, to reduce voltage and current spikes and harmonics in the multi-level stepped waveform
Data Source
AI summary
An inverter with an amplitude pulse width (APW) architecture that generates a single phase AC (Alternating Current) power waveform is disclosed. The inverter generates a multi-level stepped voltage waveform, each step of the multi-level stepped waveform having a modulated width of a selected voltage. This disclosure also relates to a personal power plant system using said inverter and a method to generate an AC power sine wave with reduced harmonic distortion.