Input ripple analysis of five-phase pulse width modulated inverters

Analysis and minimization of input current and voltage ripples of five-phase PWM inverters are presented in this paper. The analytical expressions for the RMS value of input current and voltage ripples as a function of the PWM reference signal are derived. Different to three-phase PWM inverters, it is shown that pure sinusoidal is the optimum reference signal that produces minimum input voltage ripple. Input current ripple does not depend on the employed reference signal so the ripple canpsilat be minimized by changing reference signal. Simulation and experimental results verify the analysis.

This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.

This paper proposes a three-phase AC filter inductor, which uses two soft magnetic materials, for use in three-phase pulse-width modulated (PWM) inverters. This inductor features loss reduction, achieves the same volume as conventional inductors, and has good inductance balance in each phase. First, a three-phase inductor that provides the same value of inductance in each phase is designed. Then, the inductor losses in a three-phase AC filter inductor used in a 1 kVA three-phase PWM inverter are evaluated through simulations and experiments. The conversion efficiency simulations illustrate that the proposed inductor improves the conversion efficiency. The conversion efficiencies of actual three-phase 1 kVA PWM inverters are measured, for the conventional and proposed AC filter inductors. In the experiments, the conversion efficiency in the case using the proposed inductor is found to be improved by approximately 1% at low power loads, when compared to the conventional inductors.

The aim of this paper is to obtain the AC voltage from DC source with the help of Space vector based Inverter. In a space-vector PWM (Pulse Width Modulation) inverter, which is widely used, the voltage utilization factor can be increased to 0.906, normalized to that of the six step operation. Three phase voltage-source pulse width modulation inverters have been widely used for dc/ac power conversion since they can produce a variable voltage and variable frequency power. However, they require a dead time to avoid the arm-short and snubber circuits to suppress the switching spike. Apart from these ancillary aspects, the PWM inverters have an essential problem that they cannot produce voltages as large as the six-step inverters can. That is, the dc bus voltage cannot be utilized to the maximum. To increase the voltage utilization of the sinusoidal PWM inverter, a method of the addition of the third harmonics to the reference voltage was proposed by which the fundamental component can be increased by 15.5%. In a space-vector PWM inverter, which is widely used, the voltage utilization factor can be increased to 0.906, normalized to that of the sixstep operation. On the other hand, different discontinuous PWM strategies were analyzed, where the modulation waveform of a phase has at least one segment of 60 which is clamped to the positive and/or negative dc bus for, at most, a total of 120 in a fundamental period during which no switching in either inverter arm occurs. Recently, it is shown that discontinuous PWM schemes and the space-vector PWM can be obtained by properly adding a zero-sequence voltage to the original modulation waveform.

The iron loss of an induction motor powered by the sinusoidal wave of a commercial power source has been remarkably decreased by improving the electrical steel sheet used in a motor. However, in recent years, the permanent magnet motor and induction motor used in electric vehicles are often powered by a Pulse Width Modulation (PWM) inverter which shows good controllability. Iron loss in a stator core is increased by the carrier wave used in the PWM inverter. The iron loss of a ring core specimen made of electrical steel sheets of three kinds of thicknesses was evaluated under PWM inverter excitation. The thicknesses of the prepared electrical steel sheets were 0.08 mm, 0.1 mm, and 0.35 mm, respectively. In addition, in this paper, a number of problems that present when iron loss is evaluated under PWM excitation were investigated. For instance, the influence of switching-noise and dead-time of the PWM inverter on the iron loss were examined. Moreover, relationships between the carrier frequency, the modulation index and the iron loss were investigated. As a result, it was found that the iron loss of the ultrathin electrical steel sheet does not increase much even under PWM excitation.

This paper discusses applying various switching strategies such as conventional complementary and proportional methods on a specific converter. This converter was recently presented and it can provide high voltage gain and has current ripple cancelation ability at a preselected duty-cycle. The input current ripple is zero when the converter works at a special duty-cycle. But load disturbance leads to output voltage changes that maybe cause the duty-cycle to deviate from its preselected value. In this situation, the input current ripple cannot be completely canceled. The proposed proportional strategy is an optimized method for minimizing input current ripple at other operating duty-cycles and also it provides a voltage gain lower than conventional complementary strategy. Here, the converter's performance is analyzed under two switching strategies and the effect of various strategies has been investigated on converter parameters including output voltage and input current ripple. These considerations are verified by implementing a 100-W prototype of the proposed converter in laboratory.

A key issue for power electronic converters is the ability to tackle periodic signals in electrical power processing to precisely and flexibly convert and regulate electrical power. This book provides complete analysis and synthesis methods for periodic control systems. It covers the control, compensation, and filtering of periodic signals in power electronic power processing and proposes a unified framework for housing periodic control schemes for power converters, providing a general proportional-integral-derivative control solution to periodic signal compensation in extensive engineering applications - a perfect periodic control solution for power electronic conversion. It provides number of demonstrative practical examples of the application of periodic control to: standalone constant-voltage-constant-frequency (CVCF) singlephase Pulse Width Modulation (PWM) inverters; standalone CVCF singlephase High Frequency Link (HFL) inverters; standalone CVCF three-phase PWM inverters; grid-connected single-phase inverters; grid-connected singlephase Cycloconverter type HFL rectifiers; grid-connected three-phase PWM inverters; programmable AC power sources; shunt active power filters; and UPS systems. Periodic Control of Power Electronic Converters is of key importance for researchers and engineers in the field of power electronic converter systems and their applications, for control specialists exploring new applications of control theory in power electronics, and for advanced university students in these fields.

This paper presents a new soft switching (SS) multiphase interleaved boost converter (MIBC) consisting of three boost converters (BCs) that operate rapidly and efficiently to charge a lithium-ion battery for photovoltaic (PV) power system applications. This suggested converter can operate both active power switches at zero current switching (ZCS), and when switched off, it works at zero voltage switching (ZVS), which reduces switching losses and increases switching efficiency (SF). An interleaving structure is employed to decrease the conduction losses and reduce the input current ripple (ICR) and output voltage ripple (OVR) to increase the power rating. The suggested converter regulates the input and output power by modulating the phase shift in the pulse width modulation (PWM) technique using the maximum power point tracking (MPPT) algorithm via two closed feedback loops, one for a slower external loop and the other for a faster PWM control internal loop, similar to current mode control. The suggested converter has high voltage (HV) gain due to the coupled inductors (CIs), which act as a transformer. This magnetic design structure in both the steady-state and transient states also decreases the size and enhances the converter’s performance. Finally, the suggested converter was experimentally verified on a 285W prototype, and the maximum efficiency was found to be 98%, based on modeling and experimental data.

A soft switching current-source resonant converter is presented and implemented for wide voltage applications such as fuel cells and solar power. An LLC (inductor–inductor–capacitor) converter is adopted to accomplish zero voltage (current) operation on active switches (diodes). Thus, the circuit efficiency is increased. The interleaved pulse-width modulation (PWM) converter is employed on the input side to accomplish low input ripple current. A hybrid LLC converter is adopted to achieve wide voltage operation from Vin, min to 4Vin, min and to improve the weakness of a conventional LLC converter. Half-bridge diode rectification is employed on the output side to decrease power loss on the rectifier diode. To confirm the theoretical analysis and feasibility, experimental verifications with a 500-W prototype are demonstrated in this paper.

A 2D-3D hybrid finite element method (FEM) approach is proposed for fast analysis of eddy current loss in magnets of permanent magnetic synchronous motors (PMSM) driven by a pulse width modulation (PWM) inverter. A voltage-source PWM inverter circuit coupled 3D FEM model of a PMSM was built with the commercial FEM code JMAG and the eddy current loss in the magnets of the PMSM was calculated which was extremely time-consuming. As the eddy current loss in magnets is relatively small compared with the power capacity of the motor, a voltage-source PWM inverter circuit coupled 2D FEM model is built to calculate the current waveforms ignoring the division of permanent magnets along the axial direction. Applying the calculated current waveforms from the 2D calculation to a current-source circuit coupled 3D FEM model, the eddy current loss in the magnets can be obtained which needs much less computation time. The result is very close to that obtained directly from the voltage-source PWM inverter circuit coupled 3D FEM model.

The iron loss calculation is crucial issue in making hi-power density power converter. In this paper, the iron loss separation model for AC filter inductor on a pulse-width modulation (PWM) inverter is proposed. This paper features analyzing iron loss of inductor on PWM inverter excitation which contains rectangular voltage excitation and premagnetization condition. In order to verify the proposed model, the measurement results obtained using the real PWM inverter and the calculation results using the proposed model on both the single-phase and three-phase inverters are compared. The calculated iron losses agree with measured losses within 3%. Then, the iron loss is separated into hysteresis loss and a sum of eddy current loss and excess loss by proposed model. In the PWM inverter excitation, even a magnetic material which is made to suppress the eddy current loss, such as iron powder, eddy current loss and excess loss is seen in calculated iron loss. The sum of eddy current loss and excess loss value is approximately 30%.

This research compared the performance of PWM (Pulse Width Modulation) inverter and multilevel inverter in terms of their output voltage and current total harmonic distortion (THD). The inverters were designed to have the output voltage of 220 V at 50 Hz. The input voltage for both inverters are 400 VDC. For PWM inverter, the PWM technique utilized was sinusoidal PWM (SPWM) and for multilevel converter, the number of voltage level is five with diode-clamped topology. The study included circuit implementation, analysis, and THD calculation, all of which were carried out through simulation using PSpice software. In controlling the SPWM inverter output, the adjusted parameters included amplitude modulation ratio, frequency modulation ratio, and filter components’ parameters. On the other hand, the firing angles of the switching components were designated as controlling parameters in multilevel inverter. From the study, it was found that the best THD values of the designed SPWM inverter are 4.2% (voltage) and 1.7% (current), while those of multilevel inverter are 27% and 11%, for voltage and current, respectively. Thus, it can be concluded that SPWM inverter is better than 5-level inverter for the application in solar panel due to its lower THD. In our study, 5-level inverter did not satisfy the THD requirement specified in IEEE 512-1992, i.e. 5%.

This paper proposes a multi-phase charge pump for high voltage output applications. The simple topology combines a voltage doubler with an inverting charge pump that are paralleled to provide an output voltage that is three times the input voltage. The operation of the proposed topology and the effects of multi-phasing and varying duty cycle on the input current ripple, output voltage and current ripple as well as total harmonic distortion are analyzed using LTSpice simulation. Benefits and issues from the proposed configuration will also be discussed.

In this paper, comparisons are made on various parameters of electromagnetic fields like air gap flux density (radial), flux distribution, phase currents, speed and torque of a healthy and stator inter-turn fault induction motor (IM). Using FEM (Finite Element Method), the inter-turn short circuit fault analysis of PWM (Pulse Width Modulated) inverter fed 3 phase IM is analyzed. The inter-turn fault is the initial stage of a short circuit in the stator winding and it progresses to a phase to phase fault or phase to ground fault if left undetected. When the IM is directly fed from the mains, the inter-turn fault can be identified using a popular technique known as MCSA (Motor Current Signature Analysis). But this method fails when the IM is fed from a PWM inverter due to rich noise content observed in the current spectrum due to high frequency inverter switching making it difficult to detect the fault. The electromagnetic field analysis of PWM inverter fed 3 phase IM with 12.5% and 25% stator winding inter-turn fault is carried out on a 7.5kW IM using ANSYS Maxwell FEA (Finite Element Analysis) tool. The spatial FFT spectrum of air gap flux density (radial) indicates the presence of stator winding inter-turn fault with rich noise content compared to healthy motor.

The brushless DC (BLDC) motor can be controlled either by fixed dc link voltage control with Pulse Width Modulation (PWM) or by variable dc link voltage control with Pulse Amplitude Modulation (PAM). But neither of these can be a proper method for BLDC motor. Since the PWM control induces high current and torque ripple at high speeds and PAM control limits its application at low speeds due to the small DC link voltage generation. So a drive method merging both these methods is planned with Power Factor Correction (PFC). The motor driver consists of a Bridgeless Canonical Switching Cell (BL-CSC) PFC converter and a 3-phase PWM inverter. The BL-CSC PFC converter operates on Discontinuous Continuous Mode (DCM) to achieve unity power factor at the ac mains. The speed of the BLDC motor is controlled either on the converter side by varying the input voltage of the PWM inverter or on the motor side by keeping the inverter input constant. And the bridgeless configuration of the Canonical Switching Cell (CSC) converter provides less power losses due to the partial removal of diode bridge rectifier (DBR). The hybrid drive method or the dual mode control has been analyzed using MATLAB Simulink. The PFC operation is verified and both load & supply variations are also illustrated in this paper.