330 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 54, NO. 1, FEBRUARY 2007 A New Switching Strategy for Pulse Width Modulation (PWM) Power Converters Kyu Min Cho, Member, IEEE, Won Seok Oh, Member, IEEE, Young Tae Kim, Member, IEEE, and Hee Jun Kim, Member, IEEE Abstract—This paper presents a new switching strategy for pulse width modulation (PWM) power converters. Since the proposed strategy uses independent on/off switching action of the upper or lower arm according to the polarity of the current, the dead time is not needed except instant of current polarity change. There- fore, it is not necessary to compensate the dead time effect and the possibility of arm short is strongly eliminated. The current control of PWM power converters can easily adopt the proposed switching strategy by using the polarity information of the refer- ence current instead of the real current, thus eliminating the prob- lems that commonly arise from real current detection. In order to confirm the usefulness of the proposed switching strategy, experi- mental tests were done using a single-phase inverter with passive loads, a three-phase inverter for induction motor drives, a three- phase ac/dc PWM converter, a three-phase active power filter, and a class-D amplifier, the results of which are presented in this paper. Index Terms—Dead time effect, power converters, pulse width modulation, switching strategy. I. INTRODUCTION P OWER conversion technology has recently been under- going technological advances, greatly improving the effi- ciency of power semiconductor devices that utilize such tech- nology. Thus, enhancing energy usage efficiency is also causing an increase in the demands of variable drive system of motors that use inverters, affecting the area of consumer electronics and other related industries. The usage of the three-phase ac/dc pulse width modulation (PWM) converter and the three-phase active power filter has also increased to maintain the high quality of the power source line. Generally, dead time is applied within switching signals to prevent shorting the circuit of the dc voltage source in using the bridge-type PWM power converter. This causes output voltage differences and phase deviations between reference and real values. To avoid causing detrimental effects to the control per- formance, it is necessary to compensate the dead time effects for the high performance, such as the vector control of the ac motor. Manuscript received October 2, 2004; revised May 22, 2006. Abstract pub- lished on the Internet November 30, 2006. K. M. Cho is with the Department of Information and Communications, Yuhan College, Pucheon 422-749, Korea. W. S. Oh is with the Department of Electrical Engineering, Yuhan College, Pucheon 422-749, Korea. Y. T. Kim is with the Department of Electrical Engineering, Wonju National College, Wonju 220-711, Korea. H. J. Kim is with the Division of Electrical and Computer En- gineering, Hanyang University, Kyunggi-Do 425-791, South Korea (e-mail:hjkim@hanyang.ac.kr). Digital Object Identifier 10.1109/TIE.2006.888793 There are two ways to solve the dead time effect: the dead time compensation method and the dead time suppression method. There are many methods for dead time compensation [1]–[5]. Some of these methods are very useful in practical ap- plications. Besides requiring a powerful microprocessor, such as a digital signal processing, however, such methods could not reduce the possibility of arm short in alternative switching. On the other hand, the methods for dead time suppression or minimization, which could fundamentally avoid the dead time effect, are suggested in [6] and [7]. In these methods, not only unnecessary switching actions but also the dead time is cancelled by using the independent on/off switching action of the upper or lower arm according to the polarity of the current. Therefore, the dead time compensation is not required for these methods. There are some drawbacks, however, in the practical use of [6], such as arm short at the instant of current polarity change. Moreover, small noise and current surge may cause the unexpected operation of the checking circuit for the current chattering, thus failing to produce switching signals. Finally, current intermittence usually occurs at the instant when current polarity changes in using the dead time minimization method of [7] because the method adopts sufficient threshold level in polarity detecting of real current and applies dead time from the instant of current polarity change. In order to reduce the current intermittence, another method is also proposed in [7], which adopts conventional switching method with the dead time around zero current. In that case, dead time compensation is needed. This paper presents a new switching strategy for PWM power converters. Since the proposed strategy uses independent on/off switching action of the upper or lower arm according to the polarity of the current, the dead time is not needed except in- stant of current polarity change. Therefore, it is not necessary to compensate the dead time effect and the possibility of arm short is strongly eliminated. And the current control of PWM power converters can easily adopt the proposed switching strategy by using the polarity information of the reference current instead of the real current, thus eliminating the problems that commonly arise from real current detection. In this paper, the detailed switching strategy of the proposed method is presented and the results of the experiment on the proposed switching strategy for the current control of a single- phase inverter with a passive load, a three-phase inverter for induction motor drives, a three-phase ac/dc PWM converter, a three-phase active power filter, and a class-D amplifier are shown. 0278-0046/$25.00 © 2007 IEEE