Appropriate Switching State Selection to Avoid Sapacitor Imbalance in Five-Level NPC

2018 ◽  
Vol 9 (1) ◽  
pp. 276
Author(s):  
Kuthuri Narasimha Raju ◽  
Chandra Sekhar Obbu ◽  
Ramamoorthy M
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Reference Signal ◽  
Neutral Point ◽  
Modulation Scheme ◽  
Zero Crossings ◽  
Load Demand ◽  
Capacitor Voltage ◽  
State Selection ◽  
Switching State

<p>An intrinsic problem with neutral point clamped (NPC) multilevel inverters (MLI) is unbalance of capacitor voltage. There are many mitigation techniques well established in the literature to balance the neutral point voltage for 3-level inverter. These techniques employ either Carrier based pulse width modulation (CBPWM), Space vector pulse width modulation (SVPWM) or hybrid of both the PWM techniques. Balancing becomes complicated as the level of the inverter increases due to addition of capacitor junctions. The imbalance in capacitor voltages may cause uneven voltage distribution among switching devices and sometimes may cause failure. It also increases harmonic content in its output waveform. This paper develops new modulation scheme for balancing capacitor voltages for Five-level inverter .The scheme is a hybrid PWM which is a combination of both CBPWM and SVPWM techniques. As per this scheme CBPWM is applied to meet the load demand and at the zero crossings of the reference signal, CBPWM is blocked and for one carrier cycle. During this SVPWM is applied with   appropriate switching state selection to neutralize the imbalance in capacitor voltage.</p>

scholarly journals Design and Simulation of a Single Phase Four Level Neutral Point Clamped Inverter

2019 ◽  
Vol 8 (2) ◽  
pp. 5285-5287
Keyword(s):  
Normal Mode ◽  
Pulse Width ◽  
Single Phase ◽  
Pulse Width Modulation ◽  
Reference Signal ◽  
Neutral Point ◽  
Half Cycle ◽  
Adjustment Strategy ◽  
Four Levels ◽  
Sinusoidal Pulse Width Modulation

In this paper, sinusoidal pulse width adjustment strategy for single stage four levels neutral point clamped inverter is proposed disposed of normal mode voltage. Sinusoidal pulse width modulation is much of the time utilized in modern applications. The gating sign are created by contrasting a sinusoidal reference signal and a triangular bearer sign of recurrence. The quantity of heartbeats per half-cycle relies upon the transporter recurrence

scholarly journals Carrier-Phase-Shifted Rotation Pulse-Width-Modulation Scheme for Dynamic Active Power Balance of Modules in Cascaded H-Bridge STATCOMs

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1052 ◽  
Author(s):  
Chen Xu ◽  
Jingjing Chen ◽  
Ke Dai
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Carrier Phase ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Active Power ◽  
Power Balance ◽  
Modulation Scheme ◽  
Power Distribution System ◽  
Capacitor Voltage

In the medium-voltage power distribution system, cascaded H-bridge (CHB) static synchronous compensators (STATCOMs) are widely utilized to solve power quality issues by injecting the controlled reactive current into the system. The carrier-phase-shifted (CPS) pulse-width-modulation (PWM) scheme is preferred for CHB-STATCOMs, because it can minimize the compensating current distortion and realize the relative active power balance among the H-bridge modules. This paper reveals the influence of the carrier phase difference on the module active power balance, and proposes a carrier rotation technique with a CPS-PWM scheme to address this drawback. The rotation rules were analyzed, and the rotation time was especially designed to enhance the robustness of the system. With the proposed method, the natural dynamic active power balance of each module could be achieved, and the capacitor voltage could maintain balance without the individual capacitor voltage control or the auxiliary circuits in theory. The experimental results acquired from a downscaled CHB-STATCOM prototype demonstrated the feasibility of the proposed CPS rotation PWM scheme.

scholarly journals Simulation and Design of Neutral Point Type Buck Converter

2020 ◽  
Vol 9 (3) ◽  
pp. 2767-2772
Keyword(s):  
Power Factor ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Reference Signal ◽  
Buck Converter ◽  
Neutral Point ◽  
Input Current ◽  
Output Current ◽  
Unity Power Factor ◽  
Point Type

This paper presents the simulation and design of Neutral Point Type (NPT) converters that have been used to increase power factor near one (1) which is unity. The circuit of the simulation has been design using Simulink MATLAB. The circuit was set to 50 kHz to generate Pulse Width Modulation (PWM) with carrier signal and comparing it with the reference signal. By adjusting the capacitor in the main circuit, the result of the simulation shows that the input current and voltage were in phase which is unity power factor while the output current and voltage produced having a low ripple. Thus, the simulation shows that the Neutral Point Buck type converter is suitable for maximizing power factor close to unity (1).

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