New Modulation Techniques for a Leakage Current Reduction and a Neutral-Point Voltage Balance in Transformerless Photovoltaic Systems Using a Three-Level Inverter

Lee, June-Seok; Lee, Kyo-Beum

doi:10.1109/tpel.2013.2264954

Cited by 205 publications

(80 citation statements)

References 27 publications

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“…It is obvious from (9), that the switching frequency and therefore the switching losses with the proposed SVPWM are reduced by 1/3 rd to the conventional SVPWM.…”

Section: The Switching Frequencymentioning

confidence: 97%

“…In most cases SVPWM methods are used to solve leakage current problems, because three level inverter has an inherent capability to produce the constant CM voltage by using particular SVs and thereby eliminating the leakage currents in the system. A SVPWM approach is proposed in [9] to solve the problem of leakage current and neutral point voltage variations simultaneously. However the leakage currents have some higher values due to the fact that the SVs used in any switching period do not maintain the constant CM voltage.…”

Section: Introductionmentioning

confidence: 99%

A Simplified SVPWM for Three Level Inverters to Eliminate Leakage Currents in Transformeless Photovoltaic Systems

Ansari¹,

Kim²

2016

The Transactions of The Korean Institute of Electrical Engineer

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-This paper proposes a simplified SVPWM for three level inverters in transformerless photovoltaic (PV) systems. With the proposed SVPWM the three level space vector (SV) diagram is divided into only six sectors as in conventional two level SV diagram in such a way that only seven SVs are used among all the available SVs of three level inverter. The main features of the proposed SVPWM are that it is simple to implement, less switching losses as compared to conventional SVPWM and most importantly it eliminates the leakage currents in transformerless PV systems. Detailed theoretical analysis of the proposed SVPWM are presented and verified by numerical simulations and experimental results.

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“…The condition to eliminate the leakage current is derived in [8], which is reviewed for self-integration. Fig.…”

Section: The CM Voltage and The Leakage Currentmentioning

confidence: 99%

“…In [7] and [8], the SVPWMs for reducing the leakage currents in three-level inverter system are presented. In the case of SVPWM, some duty ratio equations should be used with sophisticated vector selection algorithms based on the angle of the reference space vector.…”

Section: Introductionmentioning

confidence: 99%

A Study on a Carrier Based PWM having Constant Common Mode Voltage and Minimized Switching Frequency in Three-level Inverter

Ahn¹,

Choi²,

Lee³

et al. 2016

Journal of Electrical Engineering and Technology

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-In this paper, a carrier-based pulse with modulation (PWM) strategy for three-phase threelevel inverter is dealt with, which can keep the common mode voltage constant with minimized switching frequency. The voltage gain and the switching frequency in overall operating ranges including overmodulation are investigated and the analytic equations are presented. Finally, the leakage current reduction effect is confirmed by carrying out simulation and experiment. It will be pointed out that the leakage current cannot be perfectly eliminated because of the dead time.

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“…However, there are some drawbacks, such as high total harmonic distortion (THD) of the output waveforms, high voltage stress of the switching devices, low system efficiency and so on [1]- [3]. This is especially true in middle and high voltage, or high power conversions.…”

Section: Introductionmentioning

confidence: 99%

A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters

Lyu¹,

Hu²,

Wu³

et al. 2015

Journal of Power Electronics

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In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.

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New Modulation Techniques for a Leakage Current Reduction and a Neutral-Point Voltage Balance in Transformerless Photovoltaic Systems Using a Three-Level Inverter

Cited by 205 publications

References 27 publications

A Simplified SVPWM for Three Level Inverters to Eliminate Leakage Currents in Transformeless Photovoltaic Systems

A Study on a Carrier Based PWM having Constant Common Mode Voltage and Minimized Switching Frequency in Three-level Inverter

A New DPWM Method to Suppress the Low Frequency Oscillation of the Neutral-Point Voltage for NPC Three-Level Inverters

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