832 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 48, NO. 2, MARCH/APRIL 2012 A Voltage-Controlled PFC Cuk Converter-Based PMBLDCM Drive for Air-Conditioners Sanjeev Singh, Member, IEEE, and Bhim Singh, Fellow, IEEE Abstract—This paper deals with a Cuk dc–dc converter as a single-stage power-factor-correction converter for a permanent- magnet (PM) brushless dc motor (PMBLDCM) fed through a diode bridge rectifier from a single-phase ac mains. A three-phase voltage-source inverter is used as an electronic commutator to operate the PMBLDCM driving an air-conditioner compressor. The speed of the compressor is controlled to achieve optimum air-conditioning using a concept of the voltage control at dc link proportional to the desired speed of the PMBLDCM. The stator currents of the PMBLDCM during step change in the reference speed are controlled within the specified limits by an addition of a rate limiter in the reference dc link voltage. The proposed PMBLDCM drive (PMBLDCMD) is designed and modeled, and its performance is evaluated in Matlab–Simulink environment. Simulated results are presented to demonstrate an improved power quality at ac mains of the PMBLDCMD system in a wide range of speed and input ac voltage. Test results of a developed controller are also presented to validate the design and model of the drive. Index Terms—Air-conditioner, Cuk converter, power factor (PF) correction (PFC), permanent-magnet (PM) brushless dc mo- tor (PMBLDCM), voltage control, voltage-source inverter (VSI). I. I NTRODUCTION T HE use of a permanent-magnet (PM) brushless dc motor (PMBLDCM) in low-power appliances is increasing be- cause of its features of high efficiency, wide speed range, and low maintenance [1]–[4]. It is a rugged three-phase synchro- nous motor due to the use of PMs on the rotor. The commutation in a PMBLDCM is accomplished by solid state switches of a three-phase voltage-source inverter (VSI). Its application to the compressor of an air-conditioning (Air-Con) system results in an improved efficiency of the system if operated under speed control while maintaining the temperature in the air- conditioned zone at the set reference consistently. The Air-Con exerts constant torque (i.e., rated torque) on the PMBLDCM while operated in speed control mode. The Air-Con system with PMBLDCM has low running cost, long life, and reduced mechanical and electrical stresses compared to a single-phase Manuscript received October 16, 2010; revised June 11, 2011 and October 19, 2011; accepted December 12, 2011. Date of publication January 2, 2012; date of current version March 21, 2012. Paper 2010-IACC-410.R2, presented at the 2010 Industry Applications Society Annual Meeting, Houston, TX, October 3–7, and approved for publication in the IEEE TRANSACTIONS ON I NDUSTRY APPLICATIONS by the Industrial Automation and Control Committee of the IEEE Industry Applications Society. S. Singh is with the Department of Electrical and Instrumentation Engi- neering, Sant Longowal Institute of Engineering and Technology, Longowal 148106, India (e-mail: sschauhan.sdl@gmail.com). B. Singh is with the Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India (e-mail: bhimsinghiitd@gmail. com). Digital Object Identifier 10.1109/TIA.2011.2182329 Fig. 1. Current waveform at ac mains and its harmonic spectra for the PMBLDCM drive (PMBLDCMD) without PFC. induction motor-based Air-Con system operating in “on/off” control mode. A PMBLDCM has the developed torque proportional to its phase current and its back electromotive force (EMF), which is proportional to the speed [1]–[4]. Therefore, a constant current in its stator windings with variable voltage across its terminals maintains constant torque in a PMBLDCM under variable speed operation. A speed control scheme is proposed which uses a reference voltage at dc link proportional to the desired speed of the permanent-magnet brushless direct current (PMBLDC) motor. However, the control of VSI is only used for electronic commutation based on the rotor position signals of the PMBLDC motor. The PMBLDCMD is fed from a single-phase ac supply through a diode bridge rectifier (DBR) followed by a capacitor at dc link. It draws a pulsed current as shown in Fig. 1, with a peak higher than the amplitude of the fundamental input current at ac mains due to an uncontrolled charging of the dc link capacitor. This results in poor power quality (PQ) at ac mains in terms of poor power factor (PF) of the order of 0.728, high total harmonic distortion (THD) of ac mains current at the value of 81.54%, and high crest factor (CF) of the order of 2.28. Therefore, a PF correction (PFC) converter among various available converter topologies [5], [6] is almost inevitable for a PMBLDCMD. Moreover, the PQ standards for low power equipments, such as IEC 61000-3-2 [7], emphasize on low harmonic contents and near unity PF current to be drawn from ac mains by these drives. There are very few publications regarding PFC in PMBLDCMDs despite many PFC topologies for switched- mode power supply and battery charging applications. This paper deals with an application of a PFC converter for the speed control of a PMBLDCMD. For the proposed voltage- controlled drive, a Cuk dc–dc converter is used as a PFC converter because of its continuous input and output currents, small output filter, and wide output voltage range as compared to other single switch converters [8]–[10]. Moreover, apart from PQ improvement at ac mains, it controls the voltage at dc link for the desired speed of the Air-Con. The detailed 0093-9994/$31.00 © 2012 IEEE