AC Filter Inductor Research Articles

Proper magnetic materials selection method for AC filter inductor design used in single phase PWM inverters

The use of wide-bandgap devices such as SiC and GaN has improved the efficiency and power density of power converters compared with conventional Si devices. However, a significant portion of the efficiency loss and volume in power converters is attributed to the magnetic components, particularly the challenges of miniaturization and loss reduction. This is due to the use of nonsinusoidal waveforms, with high-frequency switching of the PWM inverter introducing ripple components that exhibit complex loss characteristics. In this study, we propose a method for selecting magnetic materials for AC filter inductors based on loss and volume considerations. In addition, the effectiveness of the proposed method is validated through experiments.

Sizing Procedure of Reactive Electric Spring

Reactive electric spring (RES) is a technique aimed at stabilizing the user voltage in presence of grid voltage variations by means of a user-encapsulated circuit. In spite of the numerous papers on the matter, no expressions are still available to size the RES elements. This paper fills this lack, by drawing up a sizing procedure of them. The procedure starts with a targeted investigation of the RES operation and exploits the outcomes to provide expressions for the values of the passive elements as well as for the voltage-current ratings of the voltage source inverter (VSI). The sizing expressions are formulated in normalized form to emphasize their dependence on the parameters of the user non-critical load. Focus of the sizing procedure is on the two RES key-elements, namely the AC-side capacitor and VSI but the AC filter inductor and the DC-side capacitor are also sized. Two options for sizing the AC-side capacitor are also discussed. At last, the study case of a user supplied by a low-voltage distribution line is considered and the sizing expressions are utilized to calculate the RES data. Experimental results, obtained by an on-purpose arranged hardware-in-the-loop (HIL) rig, validate the sizing procedure.

Power conversion efficiency prioritized AC filter inductor design for three-phase PWM inverter

This study was conducted to develop a design method of power density and efficiency maximization for three-phase pulse-width modulated (PWM) inverters that include AC filter. A tradeoff relationship exists between power density and efficiency. In general, increasing the switching frequency is known to increase the switching device loss and decrease the volume of the passive components. A three-phase PWM inverters design should consider the balance between conversion efficiency and inverter volume. However, best of our knowledge, no practical study has focused on the optimal design of a three-phase PWM inverter that includes an AC filter. This is because the iron loss of the AC filter inductor changes in complicated ways depending on the DC-bias excitation, amplitude of switching ripple current, etc. Therefore, the present authors clarified this iron loss mechanism and realized a highly accurate iron loss calculation method in previous studies. In this paper, the relationship between efficiency and volume for the switching frequency was analyzed when the AC filter inductor was designed for minimal loss by adjusting the core diameter, height, and number of winding turns. The efficiency and volume optimization achieved by designing a proper inductor was verified via comparison with a base design.

Three‐Phase AC Filter Inductor Design for Three‐Phase PWM Inverter for Conversion Efficiency Improvement at Low Load

SUMMARYThe inductor losses in a three‐phase ac filter inductor used in a three‐phase pulse‐width modulation (PWM) inverter are evaluated. First, a three‐phase inductor is designed to obtain the same value of inductance for each phase. Then, based on the design, a three‐phase inductor that uses two magnetic materials is proposed. The conversion efficiency of a 1 kVA three‐phase PWM inverter that uses the conventional and proposed ac filter inductors is simulated. Simulation results show that conversion efficiency improves. Finally, the conversion efficiency of an actual three‐phase 1 kVA PWM inverter that uses the conventional and proposed ac filter inductors is measured. In the experiment, the conversion efficiency obtained for the case of the proposed inductor improves by approximately 1% at low power load as compared to the conventional inductor. Furthermore, the calculated inductor losses are in good agreement with measured losses. Improvement in efficiency is verified trough simulations and experiments.

三相PWMインバータにおける低負荷運転時の効率改善を目的とした三相ACフィルタインダクタの提案

The inductor losses in a three-phase AC filter inductor used in a three-phase pulse-width modulation (PWM) inverter are evaluated. First a three-phase inductor is designed to obtain the same value of inductance for each phase. Then, based on the design, a three-phase inductor that uses two magnetic materials is proposed. The conversion efficiency of a 1kVA three-phase PWM inverter that uses the conventional and proposed AC filter inductors is simulated. Simulation results show that conversion efficiency improves. Finally, the conversion efficiency of an actual three-phase 1kVA PWM inverter that uses the conventional and proposed AC filter inductors is measured. In the experiment, the conversion efficiency obtained for the case of the proposed inductor improves by approximately 1% at low power load as compared to the conventional inductor. Furthermore, the calculated inductor loss es are in good agreement with measured losses. Improvement in efficiency is verified trough simulations and experiments.

Evaluation of Iron Loss of AC Filter Inductor Used in Three-Phase PWM Inverters Based on an Iron Loss Analyzer

The authors have proposed two methods for iron loss evaluation of the ac filter inductor used in a pulsewidth modulation (PWM) inverter. The first method is a loss map method, which can be used for the iron loss calculation of the ac filter inductor without using a real PWM inverter, and the second method is an iron loss analyzer (ILA), which can measure the iron loss of the ac filter inductor during every switching period on a real PWM inverter. In this paper, the measurement results obtained using the ILA and the results calculated using the loss map method on both the single-phase and three-phase inverters are compared. The calculated iron loss of the ac filter inductor on the three-phase PWM inverter is found to have a relatively large error for certain PWM pulse conditions. In order to reduce the calculation error, the authors propose a modified loss calculation method and demonstrate that the calculation error is reduced to less than 2%.

Verification of Iron Loss Calculation Method Using a High‐Precision Iron Loss Analyzer

SUMMARYBecause of the improved performance of power devices, the volume of the ac filter inductors used in high‐frequency PWM inverters has been reduced. However, the temperature rise in the filter inductor due to this miniaturization has become more pronounced. Therefore, we have proposed an iron loss calculation method for the ac filter inductor. However, the accuracy of the value calculated via the loss map method cannot be verified, because the iron loss arising during each switching period cannot be measured with conventional power measuring instruments. In order to resolve this problem, we developed an inductor loss analyzer (ILA), which allows precise measurement of the iron loss in the inductor during each switching period. The accuracy of the calculation of iron loss in the filter inductor by the loss map method was verified with the ILA. We found that the value calculated by the loss map method differed slightly from the value measured with the ILA. However, these differences can be reduced if we take into account the accurate flux density calculation and the effect of the duty ratio of PWM pulses on the loss. Finally, we verified that the loss map method can provide accurate iron loss calculations.

Iron Loss Calculation of AC Filter Inductor for Three‐Phase PWM Inverters

SUMMARYIn recent years, remarkable advancement of new power semiconductor devices, such as SiC and GaN, enables the increase of switching frequency of power converters, and hence the volume of passive components, such as ac filters and transformers, can be reduced. However, temperature rise caused by the inductor loss is increasing, and hence iron loss evaluation of the inductor is one of the most important issues to realize high power density converters. Conventionally, an improved generalized Steinmetz equation (iGSE) has proposed in order to calculate the iron loss under a pulse voltage magnetizing condition. However, accurate iron loss calculation of the ac filter inductor used in a PWM inverter cannot be realized. The authors have proposed two methods of iron loss evaluation of ac filter inductors. The first one is a loss map method which can calculate the iron loss without using a real PWM inverter. Another one is an ILA (Inductor Loss Analyzer) which can measure the iron loss in every switching period in a real PWM inverter. In this paper, comparisons of the iron loss between the ILA and the loss map method on both the single‐phase and three‐phase inverters are studied. It is found that iron loss of the ac filter inductor in the three‐phase PWM inverter which is calculated by the loss map method cause a large error on a specific condition. In order to prevent the calculation error, the authors proposed a revised loss map method and proved the effectiveness of the method.

Verification of Iron Loss Calculation Method using a High-Precision Iron Loss Analyzer

SUMMARY Because of the improved performance of power devices, the volume of the ac filter inductors used in high-frequency PWM inverters has been reduced. However, the temperature rise in the filter inductor due to this miniaturization has become more pronounced. Therefore, we have proposed an iron loss calculation method for the ac filter inductor. However, the accuracy of the value calculated via the loss map method cannot be verified, because the iron loss arising during each switching period cannot be measured with conventional power measuring instruments. In order to resolve this problem, we developed an inductor loss analyzer (ILA), which allows precise measurement of the iron loss in the inductor during each switching period. The accuracy of the calculation of iron loss in the filter inductor by the loss map method was verified with the ILA. We found that the value calculated by the loss map method differed slightly from the value measured with the ILA. However, these differences can be reduced if we take into account the accurate flux density calculation and the effect of the duty ratio of PWM pulses on the loss. Finally, we verified that the loss map method can provide accurate iron loss calculations.

Iron Loss Calculation of AC Filter Inductor for Three Phase PWM Inverters

In recent years, remarkable advancement of new power semiconductor devices, such as SiC and GaN, enables the increase of switching frequency of power converters, and hence the volume of passive components, such as AC filters and transformers, can be reduced. However, temperature rise caused by the inductor loss is increasing, and hence iron loss evaluation of the inductor is one of the most important issues to realize high power density converters. Conventionally, an improved generalized Steinmetz equation (iGSE) has proposed in order to calculate the iron loss under a pulse voltage magnetizing condition. However, accurate iron loss calculation of the AC filter inductor used in a PWM inverters cannot be realized. The authors have proposed two methods of iron loss evaluation of AC filter inductors. The first one is a loss map method which can calculate the iron loss without using a real PWM inverter. Another one is an ILA (Inductor Loss Analyzer) which can measure the iron loss in every switching period in a real PWM inverter. In this paper, comparisons of the iron loss between the ILA and the loss map method on both the single-phase and three-phase inverters are studied. It is found that iron loss of the AC filter inductor in the three-phase PWM inverter which is calculated by the loss map method cause a large error on a specific condition. In order to prevent the calculation error, the authors proposed a revised loss map method and proved the effectiveness of the method.

A Practical Iron Loss Calculation for AC Filter Inductors Used in PWM Inverters

A novel iron loss calculation method is proposed based on an iron loss map for an AC filter inductor used in a pulsewidth-modulation (PWM) inverter. The iron loss map, previously reported by the authors, is created by measuring the dynamic minor loop on the B-H plane, and this is used for the calculation of inductor iron loss in the dc chopper circuit. However, in the case of an AC filter inductor used in a PWM inverter, the iron loss map cannot be directory applied to the iron loss calculation. In this paper, an iron loss calculation for an ac filter inductor is presented by expanding the loss map method. We describe the principle of expansion and the practical procedure for the calculation, which utilizes the loss map and a conventional circuit simulator. Iron loss for the ac filter inductor under some typical modulation methods of the PWM inverter are calculated and discussed with regard to the relation between the modulation methods and iron loss. The calculated results are verified using experimental results from a 500-W inverter setup. The inductor loss and conversion efficiency of the PWM inverter are measured for each modulation method.

Design, analysis and control of compensators for distribution power systems

This paper deals with the analysis, design and control of Distribution Static Compensator (DSTATCOM) for power quality improvement in an AC distribution system. Various design criteria are considered for the design of DSTATCOM for a variety of possible functions such as voltage regulation, power factor correction and load balancing. Conventional AC power capacitors are considered in conjunction with DSTATCOM for reducing the rating of DSTATCOM. The design of DSTATCOM is carried out and the ratings of its DC bus capacitor, AC filter inductor, current and voltage ratings of solid-state devices are determined along with AC capacitors to reduce the rating of DSTATCOM.

Iron Loss Calculation Method of Filter Inductor Core on a Single-Phase PWM Voltage Source Inverter

The authors have reported a novel iron loss calculation method based on a loss-map of the magnetic materials. A distinctive feature of this method is that the iron loss on the inductors can easily be calculated in many kinds of converters. In this paper, a novel iron loss calculation method of the ac filter inductor on the PWM inverter by using the loss-map is described. This method enables to calculate the iron loss due to the dynamic minor loops by using the loss map and executing the easy circuit-simulation. The relation between the control method for the PWM inverter and the iron loss is discussed. Finally, the effectiveness of this method is verified through 500W experimental set-up.

A Novel Inductor Loss Calculation Method on Power Converters Based on Dynamic Minor Loop

This paper proposes a novel iron loss calculation method based on the loss-map of the magnetic materials. The distinctive feature of this method is that the iron loss on the inductors in many kinds of converters can easily be calculated even if the magnetizing conditions of the inductors are different. In this paper, the dynamic minor loop characteristics of the magnetic core on the condition of the switching converter are defined. Then, the dynamic measuring method of the dynamic minor loop by using the chopper circuit is presented. Next, some typical loss characteristics derived from the dynamic minor loop measurement is discussed. Also, a novel loss calculation method of the ac filter inductor on the PWM inverter by using the modified loss-map method is proposed.

Reduced harmonics PWM controlled line-side converter for electric drives

The concept for a reduced-harmonics PWM modulator, as applied for the control of a line-side power converter for a variable speed AC motor drive, is described. The PWM algorithm determines the on-state duration of each switching vector based on the observation of the time-variable voltage reference vector. Since there is no reference made to a constant-frequency carrier signal, the generated pulse patterns become asynchronous. It is the essential property of this method to produce a quasicontinuous harmonic spectrum in which all frequency components have more or less equal magnitudes. This is an advantage as compared with carrier-based PWM control schemes that exhibit high-amplitude carrier and side-band components in their harmonic spectra. The emission of acoustic noise radiated from the AC filter inductor is reduced.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>