Harmonic Injection Method Research Articles

A Study on the Reduction of Noise in Rounded Square PMDC Motors Using the Harmonic Injection Method

Present studies on the reduction of motor noise using the harmonic injection method focus on motors without mechanical brushes and commutators. Using the voltage harmonic injection method, this study proposes to reduce the noise in Rounded Square PMDC motors with mechanical brushes and commutators. The specific order and frequency of electromagnetic harmonic forces can be eliminated without losing motor performance. 2D finite element analysis and experimental testing were conducted to analyze the root cause of motor noise. Major excitation force harmonics of the motor noise were found. Theoretical and simulation models of voltage injection harmonics were built. The appropriate voltage injection harmonic was determined. The motor performance and noise was studied with and without voltage harmonic injection. It was verified that the voltage harmonic injection method was useful for noise reduction in rounded square PMDC motors. Most importantly, its performance was maintained.

The Harmonic Suppression Strategies and Efficiency Analysis of Electric Vehicle Induction Motor Drive System

The dead zone and voltage drop of inverter power switches make the currents in asynchronous motor drive system contain a large amount of harmonic. This aberration of currents waveform influences the efficiency of motor drive system. Aim at this problem, this paper proposes a harmonic injection method to eliminate the currents harmonic component when the motor is running, which improves currents waveform of motor and boosts efficiency of motor drive system. The effectiveness and real-time performance of this algorithm is verified via the simulation and the contrast experiment. Through the result of simulation, five times harmonic content decreased from 9% to 2%, the total harmonic distortion of voltage (THD) decreased from 6% to 2%, and efficiencyis increased from 98.99% to 99.95%.

Multi-Level Cascaded H-Bridge Inverter Based on Three Harmonic Injection Method

This paper introduces seven-level Cascaded H-bridge (CHB) inverter and work principle. Then, the strongpoint and disadvantage of multi-level inverter usual PWM technologies are analyzed and compared. We find that multi-level cascaded inverter based on three harmonic injection method have two advantages via analysis. The voltage modulation index can increase 1.15. The equivalent switching frequency of H-bridge inverter’s load voltage is N times of each cell switching frequency. At last, H-bridge inverter was investigated with simulation and experiment. The results prove that the analysis is correctness and validity.

A Novel Hybrid Anti-islanding Detection Method for Three-phase Grid Connected Utility Interactive Inverter of a PMSG-based Wind Power Generation

Islanding in a gird connected inverter of wind power generation system may give a bad effect on equipments or yield safety hazards on grid so it should be detected rapidly and exactly. Passive methods are simple to detect islanding by monitoring parameters of system but it has non detection zone (NDZ). Active methods are more effective to detect islanding by injecting small disturbance into output of utility interactive inverter. This paper proposes a novel hybrid anti-islanding detection method, which combines the conventional passive over/under voltage and over/under frequency (OUV-OUF) method with a new active harmonic injection method. In the proposed scheme, the active methods can be used effectively to overcome the problem caused by the NDZ. When NDZ does not exist, the passive methods can detect the islanding rapidly. The effectiveness of the proposed scheme is proved through comparative simulation results.

PMSG 기반 풍력발전용 계통연계 인버터의 신뢰성 향상을 위한 새로운 하이브리드 단독운전 방지기법

Islanding in a gird connected inverter of wind power generation system may influence a bad effect on equipments or yield safety hazards on grid so it should be detected rapidly and exactly. A passive method to detect islanding is comparatively simpler than an active method but suffers from non detection zone (NDZ). On the other hand, the active method can significantly reduce NDZ by injecting a disturbance into inverter output. To improve the reliability of islanding detection, this paper proposes a hybrid anti-islanding detection method combining the conventional passive method as well as the active method based on novel harmonic injection method using fourier transform. The proposed scheme is fast to detect islanding when NDZ does not exist because it has the nature of passive method. Under NDZ, the active method can detect occurrence of islanding reliably. The effectiveness and validity of the proposed scheme is proved through comparative simulations.

Microgrid Protection Based on Specific Current Injection

Considering that microgrid (MG) can be controlled flexibly, its short circuit-current is limited and power flow is bidirectional. The paper presents a new relay protection scheme of microgrid based specific harmonic injection method. The injective harmonic flows all over microgrid and the amplitude of specific harmonic current will enhance in fault occasion. So the above characteristic can solve the problem of fault position and the symmetric characteristic can complete the identification of fault type. The discussion about the compatibility of microgrid protection and conventional distribution network line protection. At last, the combined microgrid model is built in Matlab/Simulink environment. The simulation result demonstrated that the above method can complete the identification of fault position and type and it also can coordinate with the traditional line protection well.

Performance Investigation of Multi-phase VSI with Simple PWM Switching Techniques

This paper presents the performance of multi-phase voltage source inverter (VSI) with simple PWM switching techniques, namely the harmonic injection and offset injection method. The technique discussed in this paper is easy to implement and avoid complicated controlling algorithm adapted in SVPWM technique. The generalized switching techniques are proposed in this paper. A generalized algorithm suitable for odd number of phases is developed in Matlab/Simuli nk environment and discussed in detail for both the switching methods. The performance of the 5, 7 and 9-phase VSI is studied with the above-said switching methods. The results of the simulation are presented for different modulation indices and a comparison in terms of fundamental voltage and THD identifies the better scheme suitable for multi-phase inverter fed drives.

Decentralized Linear Permanent Magnet Synchronous Motor Control Using Harmonic Injection SPWM

This paper proposes a novel SPWM with harmonic injection method to improve the utilization ratio of bus voltage of decentralized LPMSM. In a traditional SPWM, usually, the phase voltage order is restricted independently, which results in that the bus voltage can not be used efficiently, produces voltage vector direction error, and lowers response frequency of current cycle. To solve this problem, the proposed method adopts pulse width modulation control technology with active harmonic injection to enhance the utilization ratio of bus voltage, and the theoretical analysis has been conducted from the potential difference point of view. The final results show that this method can enhance the utilization ratio of bus voltage of the high power LPMSM greatly, and improve current control, under the premise that voltage vector accuracy is not affected. This result confirm the validity of the proposed method.

Continuous PWM Strategies of Multi-Phase Inverter-Fed AC Drives

Different continuous PWM strategies of multi-phase inverter-fed ac motors are investigated from the point of view of ac motor harmonic losses. It is shown that for phase number over seven - in comparison with the space vector or with the harmonic injection methods - the natural or regular sinusoidal PWM of multi-phase system gives the best solution both from the point of view of the simplicity of realization and the value of harmonic losses. However, the stator harmonic current losses are slightly higher while the rotor harmonic current losses considerably lower than those of the three-phase system. The theoretically derived expressions for stator and rotor loss (for infinite value of switching frequency (MATHCAD program) are checked with resulting of direct computation for finite value of switching frequency (MATLAB program) and by simulation.

A Universal Selective Harmonic Elimination Method for High-Power Inverters

In medium-/high-power inverters, optimal pulse-width modulation (OPWM) is often used to reduce the switching frequency and at the same time, realize selective harmonic elimination (SHE). For both two-level and multilevel inverters, most selective harmonic elimination (SHE) studies are based on solving multiple variable high-order nonlinear equations. Furthermore, for multilevel inverters, SHE has been often studied based on the assumption of balanced dc levels and single switching per level. In this paper, the authors further developed harmonics injection and equal area criteria-based four-equation method to realize OPWM for two-level inverters and multilevel inverters with unbalanced dc sources. For the cases, where only small number of voltage levels are available, weight oriented junction point distribution is utilized to enhance the performance of the four-equation method. A case study of multilevel inverter at low-modulation index is used as an example. Compared with existing methods, the proposed method does not involve complex equation groups and is much easier to be utilized in the case of large number of switching angles, or multiple switching angles per voltage level in multilevel inverters.

Fault-Tolerant Performance of a Novel Flux-Switching Permanent Magnet Linear Machine Based on Harmonic Current Injection

A novel flux-switching permanent magnet linear machine (FSPMLM) with fault-tolerant capability is proposed. First, the structure and operation principle of the proposed FSPMLM are elaborated by comparing them to the existing FSPMLM. Second, considering the contribution of the reluctance thrust component, the thrust performance of the FSPMLM based on the static characteristics is analyzed under normal and fault conditions. The cause of thrust ripple of the proposed FSPMLM is also identified, and a fault-tolerant current control strategy based on the current harmonic injection method is implemented to compensate for the thrust ripple. Two-dimensional transient finite element method is used to investigate the thrust performance under normal and fault conditions. Finally, the results of finite element analysis are validated by the results obtained in the experiment.

Modelagem do elo de corrente contínua no domínio da frequência em sistemas assíncronos desequilibrados

Este trabalho propõe a modelagem de Elos de Corrente Contínua (HVDC, High Voltage Direct Current Link) para análise harmônica em sistemas elétricos de potência através de uma formulação no domínio da freqüência com representação completa e explícita dos sistemas CA e CC, bem como das características não-lineares dos conversores de potência. O desenvolvimento do modelo proposto é baseado no Método de Injeção de Correntes Trifásico Harmônico (MICTH) e permite a simulação sistêmica de redes CA com elo CC de alta complexidade, como sistemas com conversores de 12 pulsos e assíncronos. Os resultados das simulações do modelo proposto, no domínio da freqüência, foram validados a partir de comparações com resultados obtidos pelo ATP (Alternative Transients Program) no domínio do tempo.

Torque ripple minimization of flux-controllable stator-permanent-magnet brushless motors using harmonic current injection

Due to the nature of salient poles in both the stator and rotor, the new class of flux-controllable stator-permanent-magnet brushless (FC-SPMBL) motors still suffers from severe torque ripples. In this paper, a new torque ripple minimization approach, namely, the harmonic current injection method, is proposed and implemented in the FC-SPMBL motor. By injecting proper harmonic current components into the fundamental current, the variation of instantaneous power is kept to minimum. Thus, the torque ripple is minimized. Both simulation and experimental results show that the proposed approach can effectively suppress the torque ripple.

Predicting Inverter-Induced Harmonic Loss by Improved Harmonic Injection

This letter presents an improved harmonic injection method for determination of inverter-induced harmonic power loss across a range of induction motors rated at 1.1, 7.5, 15, and 30 kW. Techniques to obtain the necessary experimental precision and repeatability are investigated in detail. The harmonic injection method allows the machine to be tested under normal operating conditions while a range of selected harmonics are superimposed on the fundamental frequency of the pulse width modulation (PWM) waveform. This technique is validated by direct loss measurement using a specially built calorimeter capable of detecting power loss as low as a few watts in induction motors of up to 30 kW. Comparisons of segregated losses by IEEE 112 method B for the machines operating on sinusoidal and inverter-fed supplies show a good correlation between high frequency PWM harmonic loss and core loss. Core loss is not a constant proportion of total loss for any machine and neither is harmonic loss independent of machine design.

A Novel Three-Phase PFC Rectifier Using a Harmonic Current Injection Method

This paper proposes a novel circuit topology for a three-phase power factor correction (PFC) rectifier using a harmonics current injection method. In consideration of lower cost, the harmonics injection method is more suitable than a conventional six-arm pulse width modulation (PWM) rectifier. The harmonics injection current is simply generated by only one switching leg. As a result, the proposed circuit has the advantage of only two switches. An optimal injection current is achieved in order to obtain an input current of sinusoidal waveforms. This paper discusses the basic operation and optimal design method for the proposed circuit. In addition, the validity of the proposed circuit is confirmed by simulation and experimental results. An input current of almost sinusoidal waveform was obtained and an input current total harmonic distortion (THD) of 8.5% was obtained at a load of approximately 1 kW.

Voltage transfer characteristic of matrix converter

Two effective methods, namely the method of har-monic injection and overmodulation, to increase the voltage transfer ratio of matrix converter, are proposed. After the fun-damental principles of these two methods are clarified, their different characteristics are analyzed. Then their feasibility and validity are tested by simulation and physical prototype ex-periment. The results indicate that these two methods can both increase maximally the ratio of voltage transfer to 1.0, though the harmonic in the output voltage increases correspondingly. The characteristics of the harmonic generated by these two methods are also compared and the strategies to suppress it are discussed. Inspiration may be provided for further engineering application.

Comparison of Stray Load and Inverter-Induced Harmonic Losses in Induction Motors Using Calorimetric and Harmonic Injection Methods

This paper addresses two types of additional losses in induction motors. One is stray load loss resulting from loss segregation when induction motors operate from a sinusoidal supply voltage and the other is harmonic loss when induction motors operate from inverter-fed supply voltage. Both losses are of concern in machine design and operation but they are difficult to predict accurately without the use of empirical factors. This is due to their complex loss mechanisms and small magnitudes relative to output power for high efficiency machines. Compared to total machine power loss, however, they are a significant source of loss. Investigation into the correlation of the two loss components could enable effective quality control of the manufacturing of machines for use on inverter supplies. With the availability of advanced calorimetric and harmonic injection techniques, it becomes possible for these small loss components to be measured with precision. In this paper, seven induction motors ranging in power through 1.1, 7.5, 15 to 30 kW are tested for experimental comparison. Among these are four 7.5 kW machines. Test results suggest there is a need for induction motors designed specifically for inverter-fed operation.

A novel robust harmonic injection method for single-switch three-phase discontinuous-conduction-mode boost rectifiers

This paper describes a new robust low-cost harmonic-injection method for single-switch three-phase discontinuous-conduction-mode (DCM) boost rectifiers. In the proposed method, a periodic voltage is injected in the control circuit to vary the duty cycle of the rectifier switch within a line cycle so that the fifth-order harmonic of the input current is reduced to meet the IEC555-2 requirement. Since the injected voltage signal, which is proportional to the inverted AC component of the rectified three-phase line-to-line input voltages, is employed, the injected duty-cycle variations are naturally synchronized with the three-phase line-to-neutral input voltages. In addition, the injected harmonic signal naturally contains desirable higher order harmonics, such as sixth, twelfth, eighteenth, etc., which are more effective in improving total harmonic distortions (THDs) than harmonic-injection methods based on the sixth-order harmonic only.