Study of ferroresonance based on 3D peak voltage distribution and pulse suppression method

A novel pulsewidth modulation (PWM) control method is proposed in this paper. The PWM control method is called higher and lower carrier cells alternative phase opposition PWM (HLCCAPOPWM) for the hybrid-clamped multilevel inverter and based on the improvement of carrier phase disposition PWM (PDPWM). The principle of the HLCCAPOPWM method, the comparison with the carrier PDPWM method, and the analysis on output voltage spectrum are given. Simulations and experiments show that comparing with the carrier PDPWM method, the novel method can effectively reduce the number of devices switching on or off within broad modulation index range, consequently reducing switching losses, and remarkably reduce the amplitude of lower harmonics. Simulations also show the generalization of the HLCCAPOPWM method for hybrid-clamped n-level inverters and neutral-point-clamped inverters.

In this paper, total harmonic distortions (THD) and DC bus utilization of three-level T-type inverter (3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> I) are measured and classified according to the different pulse width modulation (PWM) methods. The analyses have been done for the specific values of the modulation index in the different modulation and carrier signal. Carrier signal techniques are separated to such as being phase disposition (PD) and phase opposition disposition (POD) in multi-level inverters. Performance of the proposed trapezoidal PWM (TPWM) methods that analyzed has compared the various PWM methods regarding DC bus utilization and Total Harmonic Distortion for different values of modulation index.

The inverters and control methods are applied in more and more fields with power electronics development. The technology of current hysteretic band PWM is a kind of easy and reliable control method. But the harmonic distortion of load current is big amplitude around switching frequency side band. The paper introduce a Varied Hysteretic-band Current control technique(VHBCC), this method can spreads the spectrum contents of load current around switching frequency side band, reduces the harmonic distortion of load current . At last, The results of simulation prove the method feasible and effective.

Two new pulse width modulation (PWM) methods are proposed for a dual two‐level inverter (DTLI) fed open‐end winding induction motor drive for complete elimination of zero sequence voltage (ZSV), enabling the DTLI drive to be powered from a single DC power supply only. One of the PWM methods is carefully devised and uses a single inverter only to be switched at all instants of time and dwell times of that switching inverter are derived by applying a simple volt‐second balance principle, for ZSV elimination. The second PWM method involves switching of both the inverters, for ZSV elimination in the DTLI. While the dwell times of first inverter are derived using the concept of ‘effective‐time’, whereas dwell times of the second inverter are obtained by thoughtfully exploiting the notion of ‘phase‐shift’. Additionally, torque ripple performance of the open‐end winding induction motor is theoretically analysed; ripple content is quantified to compare the performance of the proposed PWM methods. Finally, a typical PWM variant that results in the least torque ripple in the induction motor is recommended. All the envisaged ZSV elimination PWM methods and its variants are simple to implement and are first analysed, simulated and experimentally verified.

A generalized DC model for constant frequency control of Class-D converters is presented. Based on the Class-D converter with a variable capacitance switch (VCS), a generalized DC model including some losses is found from its steady-state operation waveforms by Fourier analysis. The duty ratio of the power switches is retained as an explicit parameter in the model, which makes the model also useful for pulse width modulation (PWM) control. It is found that VCS control allows a much wider range of output voltage variation than PWM control. Moreover, by small-signal perturbation of the DC model, the AC models for low frequency control- and line-to-output responses can also be obtained. An experimental Class-D converter with a VCS operating at 350 kHz is implemented to verify the derived equations.

The development of light-emitting diode (LED) technology has resulted in widespread solid state lighting (SSL) use in consumer and industrial applications. Previous researchers have shown that LEDs from the same manufacturer and operating under same use-condition may have significantly different degradation behavior. Applications of LEDs to safety critical and harsh environment applications necessitate the characterization of failure mechanisms and modes. This paper focuses on a prognostic health management (PHM) method based on the measurement of forward voltage and forward current of bare LED under harsh environment. In this paper, experiments have been done on single LEDs subjected to combined temperature–humidity environment of 85 °C, 85% relative humidity. Pulse width modulation (PWM) control method has been employed to drive the bare LED in order to reduce the heat effect caused by forward current and high frequency (300 Hz). A data acquisition system has been used to measure the peak forward voltage and forward current. Test to failure (luminous flux drops to 70%) data has been measured to study the effects of high temperature and humid environment loadings on the bare LEDs. A solid state cooling method with a Peltier cooler has been used to control the temperature of the LED in the integrating sphere when taking the measurement of luminous flux. The shift of forward voltage forward current curve and lumen degradation has been recorded to help build the failure model and predict the remaining useful life (RUL). Particle filter has been employed to assess the RUL of the bare LED. Model predictions of RUL have been correlated with experimental data. Results show that prediction of RUL of LEDs, made by the particle filter model, works with acceptable error-bounds. The presented method can be employed to predict the failure of LED caused by thermal and humid stresses.

The speed control of direct current (DC) motor for various applications is very important. In particular requirement, setting a speed DC motor as the driving equipment must be performed remotely. Under that condition, conducted a research on a DC motor speed control with pulse width modulation (PWM) method of the infrared remote control. PWM is method that may be used as a efficient DC motor speed control. Controller used TV remote control to send data to ATmega16 microcontroller through the IR receiver. This command controls the L293D driver IC to control the direction and speed of a DC motor. To calculate the speed of a DC motor, perforated disk attached to the motor shaft is used and placed between the photodiode as a sensor and the LED. The results of the research are the direction and speed of a DC motor can be set from the infrared remote control with PWM method using ATmega16 microcontroller. Furthermore, the results of these settings can be displayed on the LCD every 7 seconds.

This paper evaluates several important pulse-width modulation (PWM) methods developed to reduce the common-mode voltage (CMV) or DC-link capacitor current (DCC) of two-level three-phase voltage source inverter (VSI) in motor drive applications. In addition, a PWM selection criterion is introduced to properly utilize these advanced PWM methods in the VSI system. In the motor drive systems, the high CMV generates the large common-mode current, which may cause electromagnetic emissions and motor damages. Also, the large DCC may have an adverse effect on the life expectancy and increase the volume of DC-link capacitor. Therefore, reducing the CMV and DCC is required in modern VSI systems. So far, various PWM methods have been studied to reduce these CMV and DCC. However, they need to be fairly compared and evaluated together under the same condition to provide information so that power electronics engineers can select the appropriate PWM method when designing their motor drive systems. In this paper, the principle of these PWM methods is reviewed and their performance is analytically evaluated. Then, the PWM selection criterion is described based on the comprehensive evaluation studies. Lastly, the simulation and experimental results with an interior permanent magnet synchronous motor (IPMSM) drive system are presented to validate the presented PWM selection criterion.

The flywheel energy storage (FES) system presented in this paper is composed of four parts: the flywheel, the bearing, the motor/generator and the power converter. The control methods and strategy of the FES system in power network are introduced in detail. During the storage period and generating times, the waveform of the power converter output currents is controlled to be sinusoidal by using sinusoidal pulse width modulation (SPWM) control method, so the efficiency of the energy conversion is high and the torque ripple of the motor/generator is minimized. The control methods of starting and operating large moment of inertia of the flywheel are simulated and studied for the power converter. The latest experimental results of the FES system are introduced, and the control validity is verified through these results.

Los controladores de carga son implementados en varios sistemas electrónicos con el objetivo de proteger y controlar la carga y descarga de una batería; en el caso de los controladores utilizados en sistemas fotovoltaicos autónomos se implementan dos tipos de tecnologías, Pulse Width Modulation (PWM) y Maximum Power Point Tracking (MPPT). En este artículo se compararon dos controladores de carga con diseños originales en sistemas fotovoltaicos con las mismas especificaciones técnicas para determinar el comportamiento de cada uno bajo condiciones ambientales similares. La implementación de ambos controladores de carga se basó en software y hardware con diseños originales, utilizando tecnología PWM y MPPT. Ambos sistemas están compuestos por el controlador de carga, un panel solar de 30 W y una batería de 12 V a 18 Ah; se realizaron las pruebas experimentales de ambos controladores midiendo voltaje y corriente en el panel y en la batería en procesos de carga y descarga, observando que el controlador MPPT tiene una eficiencia promedio mayor que el controlador PWM debido a que el tipo de tecnología implementada influye directamente en la eficiencia, incluso ante valores menos favorables de radiación solar y temperatura ambiente. El controlador PWM es una opción de eficiencia aceptable y además de bajo costo respecto al controlador MPPT. En la implementación de ambos controladores se calcularon tiempos de autonomía similares.

In this paper, a pulse width modulation (PWM) control approach to speed trackong control is developed for the three-phase induction motor in electric vehicles.The PWM technique is amployed to design controllers.By incorporating the three-phase bridge recifier into the motor based on the PWM technique ,the PWM control approach is developed.The proposed control method is able to overcome the disadvatage of the motor in the traditional design procedure.In addition,it is proved that the tracking error converges to a small neighborhood of the all origin and all the closed-loop signals are bounded.The results of the MATLAB simulation illustrate the effectiveness of the proposed approach.

In this paper, a selective harmonic mitigation pulse width and amplitude modulation (SHM-PWAM) control strategy, for three-phase four-leg inverters has been proposed. In this way, the pulse amplitude modulation (PAM), which is mainly used in communication systems, is applied simultaneously with the pulse width modulation (PWM), to the three-phase four-leg inverter. Considering PAM increases the system degrees of freedom in mitigating harmonics compared with the conventional PWM strategy. The control signals of three legs voltage source inverter, mathematically expressed using Fourier-based equations to eliminate lower order nontriplen harmonics, and the fourth leg produces the harmonics that are equal to the lower order triplen harmonics which produced by the other legs. Simulation results show the performance of the SHM-PWAM strategy from the THD point of view, compared with SHM-PWM strategy.

This paper investigates the effect of (voltage source) inverter's non-linearity on the space vector pulse width modulation (PWM) method and the discontinuous PWM methods, DPWM0, DPWM1, and DPWM2. The inverter's non-linearity of dead-time and minimum pulse-width are considered. These non-linearity's impose distortion regions where their effects cannot be properly compensated. The distortion regions are identified for the various PWM methods in space vector diagram format. A method to switch between DPWM methods to avoid the distortion regions while minimizing switching losses is proposed for the middle modulation indexes. At high modulation indexes, a method to modify the DPWM1 switching function is proposed which preserves the fundamental component while taking into consideration the inverter's non-linearity. The proposed methods are experimentally verified and shown to reduce the harmonics in the motor phase currents which would normally be induced due to the inverter non-linear effects. As a result, the proposed method allows for smoother torque production

With the popularity of micro-processors, digital controllers are widely used in uninterruptible power supply (UPS) inverters. These digital control systems of UPS inverters require a time interval for sampling and computation, which sometimes affects the performance of inverters. In this paper, the problem of time delay in digital control of a UPS inverter is discussed. Then two novel pulsewidth modulation (PWM) methods, the two-polarity PWM method and the asymmetric PWM method, are proposed to handle the time-delay problem. Both of these PWM methods can achieve a wide range of duty ratio between 0.05-0.95, which is independent of inverter model. Furthermore, they are easy to implement using a digital micro-controller. Experimental results are presented in the paper to verify feasibility of the proposed PWM methods.

In the paper a Internet based teaching of Pulse Width Modulation (PWM) methods for three-level inverters is presented. In the first part the basic methods of PWM modulation are discussed. In the second part selected applets for individual teaching of PWM methods will be briefly described.