IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS, VOL. 52, NO. 10, OCTOBER 2005 2219 AZVS PWM Inverter With Active Voltage Clamping Using the Reverse Recovery Energy of the Diodes Marcello Mezaroba, Denizar Cruz Martins, and Ivo Barbi Abstract—This paper presents a zero-voltage-switching (ZVS) pulsewidth modulated inverter with active voltage clamping using only a single auxiliary switch. The structure is particularly simple and robust. It is very attractive for single-phase high-power appli- cations. Switching losses are reduced due to implementation of the simple active snubber circuit that provides ZVS conditions for all switches, including the auxiliary one. Its main features are: simple modulation strategy, robustness, low weight and volume, low har- monic distortion of the output current and high efficiency. The principle of operation for steady-state conditions, mathematical analysis and experimental results from a laboratory prototype are presented. Index Terms—Active clamping, inverters, soft commutation. I. INTRODUCTION M UCH effort has been exerted by researchers all over the world in an attempt to reduce harmonic distortion and audible noise in the output of inverters. Their objectives have been attained through an increase in inverter commutation frequencies and an appropriate modulation strategy. These measures have provided some benefits, such as a reduction in the weight and volume of the magnetic elements. However, they have caused some difficulties due to the high commutation losses in the switches and the appearance of electromagnetic interference. These factors occur mainly in inverter topologies that use the bridge inverter configuration. At the moment that the main switch turns on, the anti-parallel diode of the bridge complementary switch begins its reverse recovery phase. During this stage, the switches are submitted to a high current ramp rate and a high peak-reverse recovery current . Both contribute significantly to increasing the commutation losses and produce electromagnetic interference. To solve this problem, diverse works have been developed by the scientific community in recent years and can be divided into two groups: passive techniques and active techniques. The passive techniques are characterized by the absence of controlled switches in the switching aid circuit, while the active techniques are characterized by circuits that use controlled switches. Among the passive solutions, perhaps the most Manuscript received May 28, 2004; revised September 15, 2004. This paper was recommended by Associate Editor A. Ioinovici. M. Mezaroba is with the Power Electronics Laboratory (LEPO), the State University of Santa Catarina (UDES), 89223-100 Joinville, SC, Brazil (e-mail: mezaroba@joinville.udesc.br). D. C. Martins and I. Barbi are with the Power Electronics Institute (INEP), the Federal University of Santa Catarina (UFSC), 88040-970 Florianópolis, SC, Brazil (e-mail: denizar@inep.ufsc.br; ivobarbi@inep.ufsc.br). Digital Object Identifier 10.1109/TCSI.2005.852914 Fig. 1. Proposed circuit. widely known is the Undeland snubber [1]. This snubber pro- vides good performance in the majority of its applications, but is not capable of regenerating the energy lost in switching. To try to minimize these losses, some works have considered mod- ifications to the Undeland snubber, aiming at the regeneration of the energy lost in switching [2]–[4] and [5]. The active solu- tions are already distinguished by the use of controlled switches to obtain soft commutation. The main ones are those that use conventional pulsewidth modulation (PWM), without the need for special control circuits. One of these works is the auxiliary resonant auxiliary resonant diode pole inverter (ARDPI) [6]. This topology matches the use of PWM modulation, with the soft switching attained through a relatively simple circuit. On the other hand, it needs a high current circulating in the circuit, about 2.5 times the load current, raising the current stress in the switches. A topology very similar to the previous one is the auxiliary resonant pole inverter (ARPI) [7]. Theoretically, this circuit reduces the current levels necessary for switching, but it involves a complex control strategy. Another circuit found in literature is the auxiliary resonant commutated pole inverter (ARCPI) [8], [9], and [10]. This inverter has auxiliary switches that are only turned on when the load current is not sufficient to effect the soft switching, causing the control circuit to become very complex and dependent on the sensors. Recently, some research was carried out using the reverse re- covery energy from the diodes to obtain soft commutation in the switches of the pre-regulated rectifiers with high power factor [11] and [12]. In this paper, a zero-voltage-switching (ZVS) PWM inverter with voltage clamping across the switches, using only a single auxiliary switch, is presented. The proposed structure uses the diode reverse recovery energy technique to obtain soft commu- tation in all switches, such as the rectifier shown in [12]. 1057-7122/$20.00 © 2005 IEEE