A parallel resonant converter with pulse width modulation control

The analysis of resonant converters including the capacitance of the switches is presented. New dc characteristics are obtained for the series, parallel, and series-parallel resonant converters (SPRC). The operating regions where the converters operate with zero-voltage switching (ZVS) are determined as a function of the switch capacitance. The more pronounced effect can be seen in the series resonant converter (SRC), while the parallel resonant converter (PRC) is the most insensitive. The results of the analysis have been verified on an experimental prototype.

This paper presents a new circuit topology known as series-parallel resonant converter (SPRC), which is a combination of both the series resonant converter (SRC) and the parallel resonant converter (PRC) topologies. This topology has several advantages when compared to the individual SRC and PRC. For example, the SPRC can operate under open load conditions, and it allows for zero-current switching operation. Using the steepest descent algorithm, the state-plane equations are numerically solved to obtain the performance characteristic curves. Based on these curves, a converter design procedure can be devised. A specific design example is given.

Several papers have described the use of GTOs in zero current switching (ZCS) applications, with the goal of increasing the frequency range for medium- and high-power converters. Zero current switching with GTOs can be applied in series and parallel resonant converters, as well as in PWM inverters with commutation aid networks. The voltage and current waveforms at the devices differ in each of these applications, and different modes of ZCS can be identified. In this paper, a comparative view of the behavior and characteristics of the GTO in the different modes of ZCS is presented. The variety of ZCS waveforms is described and transferred into a unifying schematic. The behavior of GTOs in the different modes of operation is characterized, and requirements to the circuit environment are pointed out. The relations between the most important circuit parameters and some of the device waveform parameters are investigated experimentally.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A general analytical procedure is presented for the equivalent circuit modeling of resonant converters, using the series and parallel resonant converters as examples. The switched tank elements of a resonant converter are modeled by a lumped parameter equivalent circuit. The tank element circuit model consists, in general, of discrete energy states, but may be approximated by a low-frequency continuous time model. These equivalent circuit models completely characterize the terminal behavior of the converters and are solvable for any transfer function or impedance of interest. With the approximate model it is possible to predict the lumped parameter poles and zeros, and to quickly determine the relevant DC gains of the output impedance and the control to output transfer function. Closed-form solutions are given for the equivalent circuit models of both converter examples. Experimental verification is presented for the control-to-output transfer functions of both series and parallel resonant converters, and good agreement between theoretical prediction and experimental measurement is obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper proposes a new zero-current switching (ZCS) pulse width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of DC to DC PWM power converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of DC to DC PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype boost converter operating at 40 kHz.

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.

This paper proposes a photovoltaic (PV) string-level isolated DC–DC power optimizer with wide voltage range. A hybrid control scheme in which pulse frequency modulation (PFM) control and pulse width modulation (PWM) control are combined with a variable switching frequency is employed to regulate the wide PV voltage range. By adjusting the switching frequency in the above region during the PWM control process, the circulating current period can be eliminated and the turn-on period of the bidirectional switch of the dual-bridge LLC (DBLLC) resonant converter is reduced compared to that with a conventional PWM control scheme with a fixed switching frequency, resulting in better switching and conduction loss. Soft start-up control under a no-load condition is proposed to charge the DC-link electrolytic capacitor from 0 V. A laboratory prototype of a 6.25 kW DBLLC resonant converter with a transformer, including integrated resonant inductance, is built and tested in order to verify the performance and theoretical claims.

The authors introduce a computer program based on an exact analytical description of the dynamic behaviour of the parallel resonant power converter. The program provides both time-domain and state-trajectories simulation of the converter state variables under different control strategies in continuous or discontinuous capacitor voltage mode. As a result, the regulator asymptotic stability can be predicted for large-signal operation. Experimental results verify the theoretical predictions. >

Under-resonant operation of an ideal multi-resonant series-parallel power converter (MRSPC) with a capacitive output filter is modeled in this paper. This operation allows zero current switching (ZCS), which is convenient for bipolar devices. The capacitive output filtering reduces the recovery effect of the rectifier diodes and is suitable for high output voltage applications. A closed-form solution is found for this power converter, based on state space analysis using energy concepts. This approach simplifies the mathematical operations and gives better physical insight of the system variables. Based on the model, the steady-state characteristics of this power converter are derived by a simulation program, which are discussed and compared with the series resonant half-bridge power converter (SRHC). The optimum power converter parameters are found for given design requirements using computerized optimization routines. Several design examples are presented and compared with SRHC. The validity of the model is verified by SPICE simulations.

A practical method for the steady-state design of parallel resonant DC/DC power converters is presented. The method uses a set of pre-derived equations from an LLCC-type series-parallel resonant converter (LLCC-SPRC). Although four tank elements are used in an LLCC-SPRC, only two ratios of these tank elements are needed during design. The values of the four tank elements can be found from the design results. In addition to designing an LLCC-SPRC, the prederived equations can also be used to design and analyze conventional LCC-type series-parallel (LCC-SPRC), LLC-type parallel (LLC-PRC), and LC-type parallel (LC-PRC) resonant power converters. In other words, four power converters can be designed by the same equations. A design procedure along with design examples is given. Experimental circuits are implemented and measured based on the design results to verify the validity of the derived equations and the design procedure.

In this paper, a half-bridge resonant capacitance switching network LLC converter is analyzed and implemented. The half-bridge resonant capacitors switching network is adopted to reduce the input current ripple. The resonant capacitors and the input capacitors are integrated so that the components can be reduced. Two transformers are connected in series on the primary side and in parallel on the secondary side, thus the voltage stress and current stress is reduced. Since the voltage and current are automatically balanced between two transformers so that their power capacity is balanced. The operating principle is analyzed, the equivalent circuit of the resonant tank is analyzed, and some important parameters are designed. Finally, a LLC half-bridge resonant converter with 400V input voltage, 24V/600W output is implemented to verify the feasibility and effectiveness of the proposed LLC converter.

Owing to limited computational resources and the very large difference between electrical and thermal time constants, simulation for resonantly operated DC–DC converters using physical or ideal switching model is very time‐consuming or impossible. In this contribution, a novel thermal–electrical averaging model of resonantly operated DC–DC converters is proposed to reduce the computational burden and time consumption. The thermal–electrical model is based on extended describing function method. All required parameters for the thermal model can be obtained from the datasheets or on the website. The thermal–electrical models are applied in series–parallel resonant converters with LC‐type and C‐type output filters as examples, and verified by comparison with two standard simulation tools. The thermal–electrical modelling procedure proposed in this contribution can of course also be applied for other types of resonant converters, such as series resonant converter, parallel resonant converter and multi‐phase resonant converter.

The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with the grid. QZSI achieves the MPPT during the shoot through state, without additional DC-DC converter, and simultaneously delivering the AC power to the grid or motor load. The quasi components (L and C) sizes are reduced by increasing the switching frequency of the converters. But the switching losses of the converter will dominate at the higher frequencies. To minimize the switching losses of the converter, this paper proposes reduced switching loss single stage inverter for high power applications. Using only six devices rated at supply voltage, the QZS resonant converter can operate properly by adding resonant inductor and capacitor to the ac side of each phase. The proposed converter can control the output with true pulse width modulation (PWM) at high frequency and the Zero Voltage Switching (ZVS) and Zero Current Switching is achieved at every switching cycle. The detailed analysis, modulation and simulation are presented to verify the operating principle of the QZS resonant converter.

LowQ resonant converter, such as series-series resonant converter, series resonant converter, and parallel resonant converter (PRC), are highly flexible and highly tolerant to coil misalignments. However, these kinds of topologies cannot be employed to the wide air-gap, low-coupling transformers because of their inadequate magnetizing inductance. On the other hand, highQ multiple-resonant converters such as series-PRC) and series-SPRC are very suitable for low-coupling compact wireless transformer applications. However, because these multiresonant topologies have several resonant pairs resonating at a single frequency, these parameter values ought to be consistent throughout the operating conditions to resonate at the same frequency. However, since the wireless power transfer (WPT) applications are required to be flexible and convenient to the customers, the wireless transformers are not supposed to be rigid and stationary. To solve the problem, a controllable inductor for a highQ multiresonant WPT system is proposed to extend the soft switching region and to keep the resonant circulating energy minimum even at resonant mismatch conditions caused by the misalignments or temperature variations of the wireless transformer coils. The performance enhancement of the multipleresonant wireless converter is validated using the proposed controllable inductor technique, and also the feasibility of the proposed technique is proven under different mismatch conditions through 200-W hardware experimental results.