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 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.     

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

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 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.     

Phase Correction for High Precision Measurement of Iron Loss Using H‐coil Method

The accurate magnetic properties of electrical steel sheets are important for the development of high‐efficiency electromagnetic devices. In particular, the H‐coil method is a useful technique for accurately measuring magnetic field strength in a single sheet tester. Therefore, we developed a tester for magnetic field properties using the H‐coil method, referred to as the stress load type single sheet tester (S‐SST), and a problem was found in iron loss measurement at a high flux density of 1.6 T or more. In this paper, it is shown that the cause of this problem is the phase difference between the induced voltage in the H‐coil and the B‐coil. Because the phase difference makes the B–H loop slightly twisted near the tip point, the iron losses are evaluated low. Thus, we propose a method of determining the phase correction values. These values are measured in the absence of a specimen in the S‐SST measurement system, and the phase correction method for induced voltage in a coil is investigated. Finally, ideal results for the correction of iron loss in nonoriented electrical steel sheets are shown. The proposed method is effective for the calibration of a single sheet tester using the H‐coil method.     

Iron Loss Analysis of Permanent Magnet Motors Fed by PWM Inverter

Carrier harmonic losses that consist of iron loss, eddy current loss, and ac copper loss are produced in a permanent magnet machine driven by a PWM inverter. It is already known that a higher motor inductance can lead to lower carrier harmonic losses. This paper investigates the carrier harmonic loss composition of two motors with identical dimensions but different inductances. The results of finite element analysis (FEA) showed that the eddy current loss in the iron core accounts for most of the carrier harmonic loss. It is also shown that the carrier harmonic loss of the iron core is quantifiable using theoretical calculations.     

Iron Loss Characteristics of Electrical Steel Sheet under Inverter Excitation by Power Semiconductor with Extremely Low On‐Voltage Property

In this study, it is demonstrated that the iron loss from the SiC‐MOSFET, which represents a new power semiconductor with an extremely low on‐voltage for electric machine drives, is almost the same as that from an Si‐IGBT, which is a conventional power semiconductor. In order to evaluate the iron loss characteristics when an SiC device is used, two single‐phase pulse width modulation inverters were built and used for the excitation of a ring made up of electrical steel sheet. One of the inverter employed an SiC‐MOSFET, and the other inverter employed an Si‐IGBT. The iron losses for the two inverters are compared.     

Performance Verification of High‐Efficiency PV Power Conditioner Integrated with SiC MOSFETs and Cooperative Control Method

A high conversion efficiency is always required for photovoltaic power conditioners to utilize PV‐generated DC power with minimal loss. The cooperative control method has been developed as one of the control methods that improves the conversion efficiency, which is applicable to nonisolated power conditioners consisting of a boost converter and an inverter. In the cooperative control method, the boost converter creates part of the AC voltage waveform, and either the boost converter or inverter performs switching only during a required period. Therefore, it has the advantage of reducing switching losses. In this paper, we present a study of a cooperative‐control‐type power conditioner assuming its use in grid‐connected operation and the results of a performance verification of prototype power conditioner. A microcontroller is used for cooperative control. The experimental results show that the prototype power conditioner integrated with SiC MOSFETs and the cooperative control method achieves an efficiency of 97.4% at an output of 5.5 kW.     

盘式感应电动机铁耗的计算

由于盘式电机的结构不同于常规电机，使它们的磁密转换系数、铁重以及铁耗的计算也不同。本文根据盘式感应电动机的结构特点，提出铁耗计算的较优方法和试验值相吻合。     

逆变器端RLC滤波器的参数设计与损耗计算

在长线电缆传输高频脉宽调制(PWM)脉冲的过程中,逆变器输出端通常用RLC滤波器来抑制电机端过电压和高频振荡,但对相关滤波器参数优化设计的研究较少。基于滤波器电感、电容最小值与PWM脉冲上升时间与滤波器电阻之间的定量关系,对上升时间和滤波器电阻的选取原则进行改进,从而有效减小滤波电感和电容,实验验证了所提改进方法的合理性。     

Effect of Carrier Frequency and Circuit Resistance on Iron Loss of Non‐Oriented Electrical Steel Sheet under Single‐Phase Full‐Bridge PWM Inverter Excitation

Because of the development of power electronics technology, pulse width modulation (PWM) inverters are now being used to drive motors in order to achieve precise and energy‐efficient control. Precise estimation of the increase in iron loss due to the high harmonic components of flux, including the carrier frequency, is important in the design of motors excited by a PWM inverter. We measured the iron losses of non‐oriented electrical steel sheets that were excited using a single‐phase full‐bridge PWM inverter, and examined the influence of the carrier frequency and circuit resistance on the iron loss. We showed that the iron loss increased because of the generation of minor loops when the circuit resistance was high. Therefore, the circuit resistance should be decreased in an actual motor system.     

考虑铁损时交流电磁机构动态特性的计算

介绍了交流电磁机构动态特性的计算方法。给出了一种考虑铁损时用瞬态磁路法计算激磁线圈电流和电磁吸力的新方法,并对采用插值法求解电磁机的动态特性进行了讨论。     

PWM激励下异步电机铁耗等值电阻模型

通过分析PWM激励下异步电机铁耗变化的特点,提出了一种综合考虑电机运行工况和PWM波形特性的铁耗等值电阻模型。基于铁耗分离原理,使用三个电阻分别等效电机铁耗的磁滞分量、经典涡流分量和异常涡流分量,并推导了正弦激励下各个电阻分量的表达式;进而通过分析PWM激励与正弦激励下铁耗间关系,对正弦激励下铁耗模型进行修正,获得PWM激励下铁耗模型;最后提出了确定该模型参数的实验方案。所建模型中各个电阻分量随电机运行频率和PWM波形的调制系数变化而变化,且变化规律各不相同,提高了电机铁耗计算的准确性。仿真和实验验证了该模型的正确性和有效性。     

PWM型逆变器输出谐波对异步电机损耗的影响分析

借助有限元法对PWM型逆变器供电的异步电机进行了损耗分析。由于逆变器整流方式的不同,产生了不同的电压波形,文中结合有限元法和异步电机的模型,对异步电机由于谐波作用产生的损耗进行了分析。通过把磁场分布分割为若干谐波分量,以找出谐波磁场的作用和主要的损耗因素。由此证明了转子表面的损耗大多由谐波产生。高次谐波使电动机产生脉动转矩,使输出机械特性变差,同时降低了传动系统运行的稳定性,并由于谐波损耗的产生,使电动机附加损耗增加,从而降低传动系统的能量转换效率。所以对异步电机必须考虑高次谐波的影响。     

A novel strategy for a high‐power utility interactive inverter with a series active filter

High‐power utility interactive inverters used for large‐capacity energy storage systems are composed of multiple connected inverters, in order to realize high efficiency and high performance of the harmonic elimination characteristic simultaneously. Some disadvantages of multiple connected inverters, such as harmonic current flowing from an inverter unit to the other one, and increase of the number of inverter units, cannot be overcome easily. This paper presents a novel strategy for a high‐power utility interactive inverter, which is composed of a large power with low‐switching‐frequency PWM inverter (high‐power PWM inverter), an LC passive filter, and a series active filter (series AF). Because harmonic components contained in the utility line current are absorbed by the series AF, the switching frequency of the PWM inverter can be selected to about 1 kHz. In addition because the power capacity and the output voltage of the series AF can be suppressed lower than 10% of the power capacity and the output voltage of PWM inverter, low‐voltage and high‐speed power devices can be applied to the series AF. Consequently, high power, high efficiency, and high harmonics elimination performance can be realized without increasing the number of inverter units. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(2): 57–66, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10048     

非正弦激励下磁心损耗的计算方法及实验验证

在电力电子装置中,磁性元件的输入电压波形往往不是正弦波,研究非正弦激励下电力电子装置中磁心损耗的计算方法有重要意义。首先介绍正弦激励下磁心损耗的计算方法,在此基础上研究了非正弦激励下磁心损耗的计算方法,得到了修正铁耗分离法和修正Steinmetz经验公式法计算式。其次,考虑磁心叠片的趋肤效应,对修正铁耗分离法做了进一步改进。然后,对环形非晶和纳米晶磁心的损耗测量结果进行数值拟合,得到了非正弦激励下两种方法的解析计算式,并比较了应用两种计算方法的损耗计算结果。最后,分别对环形非晶和纳米晶磁心开展非正弦激励下的磁心损耗测量实验,将实验结果和上面两种计算方法的解析结果进行比较,验证了非正弦激励下两种计算方法的准确性。     

Optimization of Switching Phase of a Single‐Phase PWM dc–ac Inverter

The purpose of this paper is to improve the efficiency of the single‐phase pulse width modulation (PWM) dc–ac inverter based on optimization of the switching phase of the PWM. Improvement of the efficiency means improvement of the quality of the output waveform and the conversion efficiency, and reduction of the switching loss. We propose an evaluation method involving minimization of the evaluation function by using the particle swarm optimization algorithm. We improve efficiency by setting a criterion for each index. As a result, the proposed algorithm can reduce high harmonic components in switching times shorter than the conventional triangle wave comparison method. Also, we confirm that the algorithm can improve the quality of the output waveform and the efficiency of conversion.     

双极性单相SPWM逆变器滤波电感电流值的近似计算方法

逆变器满负荷时的电感电流有效值和电流峰值是滤波电感设计的两个重要参数。分析了双极性单相SPWM逆变器的输出电压特性及LC滤波电路的特性,提出了一种近似计算滤波电感电流有效值和电流峰值的方法。与仿真结果相比较,本近似计算方法具有较高的计算精度,为正确选择滤波电感提供了依据。     

铁磁损耗对直接转矩控制低速性能的影响及补偿方法研究

为了探讨铁磁损耗对直接转矩控制（DTC）性能的影响,在两相静止坐标系下建立了考虑铁磁损耗的异步电机动态等效数学模型。基于考虑和不考虑铁磁损耗两种情况对传统DTC控制性能进行了分析比较,结果表明铁磁损耗会造成电机低速时的实际输出转矩减小,电机的动态响应速度变慢。并在基于考虑铁磁损耗的情况下提出一种对铁磁损耗补偿的方法,使传统的估算转矩更接近于实际输出转矩,提高了转矩控制性能。实验结果证明了补偿控制方法的有效性,并能改善DTC系统的低速性能。     

Development of Multiresonant ZVS High‐Frequency Inverter

A novel multiresonant zero‐voltage switching (ZVS) high‐frequency inverter has been developed. This inverter is capable of supplying a current of large amplitude to a load as a result of suppression of the main switch current. The principle of the ratio of the main switch current to the load current is theoretically demonstrated using the capacitance ratio. High‐frequency operation with ZVS is verified experimentally.     

一种逆变器损耗分析与计算的新方法

提出一套完整的逆变器损耗分析计算方法,并以双Buck逆变器为例进行实际的计算与分析。在对开关损耗进行分析时考虑了器件间的相互影响和作用,因而更为精确。通过损耗计算得出逆变器损耗的主要组成部分及其主要的决定因数,对逆变器初始设计或进一步改进具有重要指导意义。该文提出的损耗计算方法适用于包括滞环电流控制型逆变器在内的各种变换器。     

采用BUCK电路的低电感无刷直流电动机转矩脉动与损耗分析

通过分析低电枢电感无刷直流电动机的特点,在无刷直流电动机驱动器逆变电路前级采用BUCK变换电路实现电压的调整,在逆变电路中采用Hall信号换相而不叠加PWM斩波信号。通过建立无刷直流电动机及其驱动电路的模型,并对其进行仿真分析,结果表明采用BUCK变换电路后能够减小电机的相电流和母线电流的脉动,减小电磁转矩脉动,消除直流端反向电流,电机铁损耗和铜损耗也大大降低。