Wavelet PWM Technique for Single-Phase Three-Level Inverters

Chun-Fang Zheng,Bo Zhang,Dong-Yuan Qiu,Xiao-Hui Zhang,Le-Ming Xiao 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.6

The wavelet PWM (WPWM) technique has been applied in two-level inverters successfully, but directly applying the WPWM technique to three-level inverters is impossible. This paper proposes a WPWM technique suitable for a single-phase three-level inverter. The work analyzes the control strategy with the WPWM and obtains the design of its parameters. Compared with the SPWM technique for a single-phase three-level inverter under the same conditions, the WPWM can obtain high magnitudes of the output fundamental frequency component, low total harmonic distortion, and simpler digital implementation. The feasibility experiment is given to verify of the proposed WPWM technique.

Control Strategies of Active Power Line Conditioners in Single-Phase Circuits

Toshihiko Tanaka,Masayuki Okamoto,Eiji Hiraki 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper deals with two control strategies for the active power line conditioners in single-phase circuits. The first one is a constant dc capacitor voltage control based strategy, which is commonly used in the active power line conditioners. Any detection blocks of the fundamental active, reactive, and harmonic components are not necessary in this method. Thus we offer the simplest way to compensate the fundamental reactive and harmonic currents on the source-side. The other is a reactive power control based strategy, which is with the correlation and cross-correlation coefficients between the feeder voltage and load current. Controlling the detected fundamental reactive component with the cross-correlation coefficient on the source-side reduces the capacity of the PWM inverter, which performs the active power line conditioners. The basic principles of the proposed control strategies are discussed in detail, and then applied to the single-phase active power line conditioners in single-phase based distribution systems. These sigle-phase distributin systems are used in the single-phase three-wire systems and electrified railways. The validity and excellent practicability of the proposed control strategies are confirmed by experimental results.

Single Phase Commutation Control of Open-End Winding PMSM Fed by Single DC-Link Dual Inverter

Gyu Cheol Lim,Hyeon-gyu Choi,Jung-Ik Ha 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a single phase commutation control method of open-end winding permanent magnet synchronous machine operated by a single DC-link dual inverter. For the control of open-end winding PMSM, a per-phase current control method which independently controls each phase is adopted. The proposed method allows the open-end winding PMSM to maintain the output torque while the only single phase of three phase windings conducts. In order to maintain the constant output torque with single phase commutation, modification of current reference is introduced. When a single phase is commutating, the other two phases do not conduct nor does the switching happen. The switching loss is significantly minimized with a small increase of conduction loss resulting in the improvment of overall drive system efficiency. The validity of the proposed control method was verified with simulation result.

PWM Control Techniques for Single-Phase Multilevel Inverter Based Controlled DC Cells

Mahmoud A. Sayed,Mahrous Ahmed,Maha G. Elsheikh,Mohamed Orabi 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103.

Analysis of Phase Error Effects Due to Grid Frequency Variation of SRF-PLL Based on APF

Seong, Ui-Seok,Hwang, Seon-Hwan The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.

Analysis of Phase Error Effects Due to Grid Frequency Variation of SRF-PLL Based on APF

성의석,황선환 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.

Analysis of Phase Error Effects Due to Grid Frequency Variation of SRF-PLL Based on APF

Ui-Seok Seong,Seon-Hwan Hwang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.1

This paper proposes a compensation algorithm for reducing a specific ripple component on synchronous reference frame phase locked loop (SRF-PLL) in grid-tied single-phase inverters. In general, SRF-PLL, which is based on all-pass filter to generate virtual voltage, is widely used to estimate the grid phase angle in a single-phase system. In reality, the estimated grid phase angle might be distorted because the phase difference between actual and virtual voltages is not 90 degrees. That is, the phase error is caused by the difference between cut-off frequency of all-pass filter and grid frequency under grid frequency variation. Therefore, the effects on phase angle and output current attributed to the phase error are mathematically analyzed in this paper. In addition, the proportional resonant (PR) controller is adapted to reduce the effects of phase error. The validity of the proposed algorithm is verified through several simulations and experiments.

Resonance Elimination of LLCL Filters Based on Virtual Resistor for Single-Phase PWM Inverters

Cheol-Ju Bae,Payam Alemi,Dong-Choon Lee 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, an active damping control scheme based on virtual resistors is proposed for LLCL filters in the single-phase grid inverters. In comparison with the well-known LCL filters, a very small-size inductor is inserted in series with the filter capacitor, by which the series resonance at the switching frequency may occur. By the LC filter branch, the switching ripple in the grid-side current is suppressed, from which the inductor size in the grid side is minimized. However, the resonance phenomena in this filter may also occur, which needs to be investigated to guarantee the system stability. A resonance suppression scheme based on virtual resistors is proposed for LLCL filters in single-phase grid inverters. The simulation results for a 3-kW single-phase system have verified the effectiveness of the proposed control scheme.

Single-Phase Multilevel PWM Inverter Based on H-bridge and its Harmonics Analysis

최우석,남해곤,박성준 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.

Single-Phase Multilevel PWM Inverter Based on H-bridge and its Harmonics Analysis

Choi, Woo-Seok,Nam, Hae-Kon,Park, Sung-Jun The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

The efficient electric power demand management in electric power supply industry is currently being changed by distributed generation. Meanwhile, small-scale distributed generation systems using renewable energy are being constructed worldwide. Several small-scale renewable distributed generation systems, which can supply electricity to the grid at peak load of the grid as per policy such as demand response programs, could help in the stability of the electric power demand management. In this case, the power quality of the small-scale renewable distributed generation system is more significant. Low prices of power semiconductors and multilevel inverters with high power quality have been recently investigated. However, the conventional multilevel inverter topology is unsuitable for the small-scale renewable distributed generation system, because the number of devices of such topology increases with increasing output voltage level. In this paper, a single-phase multilevel inverter based on H-bridge, with DC_Link divided by bi-directional switches, is proposed. The proposed topology has almost half the number of devices of the conventional multilevel inverter topology when these inverters have the same output voltage level. Double Fourier series solution is mainly used when comparing PWM output harmonic components of various inverter topologies. Harmonic components of the proposed multilevel inverter, which have been analyzed by double Fourier series, are compared with those of the conventional multilevel inverter. An inverter prototype is then developed to verify the validity of the theoretical analysis.