Parallel Resonant Power Converter Research Articles

An RC load model of parallel and series-parallel resonant DC-DC converters with capacitive output filter

A novel analytical methodology is proposed and applied to investigate the steady-state processes in voltage-fed parallel and series-parallel resonant DC-DC power converters with a capacitive output filter. In this methodology, the rectifier, output capacitor and load are replaced by an equivalent circuit which includes a capacitor and resistor connected in parallel. Excellent agreement was obtained when comparing numerical values calculated by the proposed model to cycle-by-cycle SPICE simulation and to the numerical results of earlier studies.

High-power-factor electronic ballast with constant DC-link voltage

This paper presents a high-power-factor (HPF) electronic ballast based on a single power processing stage with constant DC-link voltage. The switching frequency is controlled to maintain the DC-link voltage and the voltage across the switches constant, independently of changes in the AC-input voltage. This control method assures zero-voltage switching (ZVS) for the specified AC-input-voltage range. Besides, with an appropriate design of the fluorescent lamps' drive circuit, the lamps' power can be kept close to the rated value. The power-factor-correction (PFC) stage is formed by a boost power converter operating in the discontinuous conduction mode, which naturally provides HPF to the utility line. The fluorescent lamps are driven by an unmodulated sine-wave current generated from an LC parallel resonant power converter which operates above the resonant frequency to perform ZVS. Theoretical analysis and experimental results are presented for two series-connected 40 W fluorescent lamps operating from 127 V -15% to +10% 60 Hz utility line. The switching frequency is changed from 25 to 45 kHz to maintain the DC-link voltage regulated at 410 V, which leads to a constant output power. The experimental results confirm the high efficiency and HPF of this electronic ballast.

High-power-factor electronic ballast operating in critical conduction mode

A high-power factor (HPF) electronic ballast, which exhibits low switching losses, is presented in this paper. The proposed topology is based on a single power-processing stage, which provides high-frequency voltage to fluorescent lamps and HPF to the utility line. The lamps are driven by a self-oscillating LC parallel resonant power converter of great simplicity and attendant low cost and increased reliability. HPF is achieved by using a nonconventional boost power converter operating in critical conduction mode. Theoretical analysis and experimental results for two 40-W fluorescent lamps operating at 50 kHz from a 127-V utility line have been obtained, which demonstrate the high efficiency and HPF of this electronic ballast.

Robust controller design for a parallel resonant converter using /spl mu/-synthesis

DC-to-DC resonant power converters have been the subject of much attention recently. These power converters have the potential to provide high-performance conversion without some of the problems associated with classical pulse-width modulation (PWM)-based converters, thus allowing for smaller, lighter power supplies. However, in order to achieve this, a suitable control circuit, capable of maintaining the desired output voltage under different operating conditions, is required. In the past, small-signal models obtained around the nominal operating points were used to design controllers that attempted to keep the output voltage constant in the presence of input perturbations. However, these controllers did not take into account either load or components variations, and thus could lead to instability in the face of component or load changes. Moreover, the prediction of the frequency range for stability was done a posteriori, either experimentally or by a trial-and-error approach. In this paper, the authors use /spl mu/-synthesis to design a robust controller for a conventional parallel resonant power converter. In addition to guaranteeing stability for a wide range of load conditions, the proposed controller rejects disturbances at the power converter input while keeping the control input and the settling time within values compatible with a practical implementation. These results are validated by means of detailed nonlinear circuit simulations obtained using PSpice.

Large signal analysis of the LCC-type parallel resonant converter using discrete time domain modeling

Discrete state space modeling of the LCC-type parallel resonant power converter is presented. Using these large signal equations, small signal modeling of the power converter is obtained. State variable feedback control has been integrated with the linear small signal state space model and the associated control aspects are studied. The small signal equivalent circuit model has also been obtained. The small signal state space model has been used to study the small signal behavior of the power converter for open loop and closed loop operation for parameters like control to output transfer function, audio-susceptibility and output impedance. Theoretical results have been experimentally verified. >

Small signal analysis of the LCC-type parallel resonant converter using discrete time domain modeling

Discrete state-space modeling of the LCC-type parallel resonant power converter is presented. Using these large signal equations, small signal modeling of the power converter is obtained. Multiple loops have been used for the closed loop operation. State variable feedback control has been integrated with the linear small signal state-space model and the associated control aspects are studied. The small signal state-space model has been used to study the small signal behavior of the power converter for open loop and closed loop operation for parameters like control to output transfer function, audio-susceptibility and output impedance. Key theoretical results have been experimentally verified.

Half-cycle control of the parallel resonant converter operated as a high power factor rectifier

A half-cycle control technique for the parallel resonant power converter operated as a high power factor rectifier is introduced in this paper. Switching of the bridge power transistors is determined such that the bridge input current averaged over a half switching cycle exactly follows the reference proportional to the input voltage. Zero current switching and below-resonance operation are guaranteed, while control of the input current is the fastest possible, regardless of the operating point. In contrast to conventional regulators, the performance is preserved under both small and large signal variations, and also for large variations of the power-stage parameter values. Fast response, stability and robustness are experimentally verified on a 1.4 kW prototype.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Realization of the powering/regenerative operation of the induction motor by the parallel resonant power converter and proposal of a novel circuit topology

AbstractA resonant power converter for the low switching loss power conversion must be achieved for high‐frequency zero voltage switching or zero current switching. The important matters of the continuation of resonant phenomena are the control strategy of resonant initial current and the clamp circuit for suppressing the resonant link voltage.The control strategy of the resonant initial current is discussed and the powering and regenerative operation are shown successfully in the steady state and transient state by experimental test.Finally, a new resonant dc link dual converter system is proposed and it is confirmed that the voltage stress of the resonant capacitor and the rms value of electrolytic capacitor current are decreased with experimental test also.

Realization of the Powering/Regenerative Operation of the Induction Motor by the Parallel Resonant Power Converter and Proposal of a Novel Circuit Topology.

A resonant power couverter for the low switching loss power conversion must be achieved high frequency zero voltage switching or zero current switching. The important matters of the continuation of resonant phenomena the control strategy of resonant initial current and the clamp circuit for suppressing the resonant link voltage.We discuss the control strategy of the resonant initial current and show the powering and regenerative operation successfully in the steady state and transient state by experimental test.And, we propose a new resonant DC link dual converter system and confirm that the voltage stress of the resonant capacitor and the rms value of electrolytic capacitor current are decreased with experimental test also.

A parallel resonant converter with postregulators

A parallel resonant power converter (PRC) with postregulator(s) power synchronized to the primary switching frequency is investigated for discontinuous-conduction mode operation. It is analyzed with a magnetic amplifier, which blocks the rising edge of the secondary voltage, and with a synchronized buck regulator, which blocks part of the trailing edge of the secondary voltage waveform under the steady-state conditions. As a result, it has been shown that magnetic amplifiers are not suitable for resonant mode power converters, since the step change of the load from low to high during the same switching period as the primary makes the operating conditions worse. However, postregulators that block the trailing edge of the secondary voltage waveform do not adversely affect the operating conditions of PRC and work satisfactorily. As an alternative, a PRC with a magnetic postregulator is presented. An offline 150 W 250 kHz PRC is designed with a magnetic postregulator for a personal computer application, and experimental waveforms are included.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Characteristics of load resonant converters operated in a high-power factor mode

The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis and design of a series-parallel resonant converter with capacitive output filter

The objectives are to propose a LCC-type parallel resonant power converter with a capacitive output filter, to present its different operating modes and analyze the converter for these modes, to obtain design curves based on the analysis to present a simple design procedure for the proposed converter, and, finally to provide experimental results. A high-frequency link series-parallel resonant power converter with capacitive output filter is proposed and analyzed using the state-space approach. Analysis shows that the converter enters into three different modes. The normalized load current and other component stresses are plotted against the converter gain. Detailed experimental results are presented to verify the theory. >