EMI SMPS & Start Circuit Control & Driving Circuit IM Input +15 V @ 50 mA +5V @ 100 mA The Mains 230 V 50-60 Hz Vbus , Ibus , Ths ... AUXILIARY POWER SUPPLIES IN LOW POWER INVERTERS FOR THREE PHASE TESLA’S INDUCTION MOTORS Petar J. Grbovic Schneider Toshiba Inverter Europe, R&D 33 Rue Andre Blanchet, 27120 Pacy-Sur-Eure, France petar.grbovic@fr.schneider- electric.com Tel: +33 2 3278 1923, Fax: +33 2 3278 1889 Slobodan N. Vukosavic Department of Electrical Engineering, University of Belgrade Bulevar Kralja Aleksandra Obrenovica 73, Serbia boban@ieee.org Tel: + 381 11 3218369 Abstract This paper describes and proposes auxiliary power supplies that may be employed to feed control and gate drive circuits in a three phase micro inverter for a three phase Tesla’s induction motor. The proposed solutions use bus voltage and output voltage ripple, and the dc link current ripple in the motor converter as primary source of the energy to provide regulated output voltage of approximately 15V at load up to 100mA I. Introduction In power converters such as PWM inverters, rectifiers and dc-dc converters, an auxiliary power supply is required to feed analog and digital control circuit, and gate drivers of power switches (usually IGBTs or MOSFETs). The auxiliary output voltage is usually 15 V at load up to 100 mA. There are several possible topologies used of used auxiliary power supplies. The, applied topology depends on conditions, such as input voltage, output voltage, power rating, dynamic and static regulation, ripple and insulated/non-insulated from the main dc bus. Application we would focus in this paper are PWM inverters used to feed a low power three phase Tesla’s induction motors. Block diagram of a single phase supplied motor converter is given in Fig 1. The converter consists on the power stage, a control and driving unit, and auxiliary power supply with start up circuit. A commonly used topology is an insulated fly- back converter, supplied from main dc bus. The input voltage is 300 up to 1200 V [1,2,9]. In some applications where the size and cost of the power supply are critical, a standard power supply is not appropriate solution. The main problem is cost and volume of the power supply. In these applications other type of power supply ahs to be used. Yakow, Zelster, and Ivensky, analysed and proposed a snubber network employed as a power supply in boost converters [4,5]. An auxiliary power supply used in boost power factor correction (PFC) converters is based on topology with auxiliary inductor coupled with the main boost inductor [7]. This topology may be used in motor drives having input power factor correction circuit. Fig. 1. A block diagram of a typical low power motor converter Three new power supplies are proposed in this paper. The proposed auxiliary power supplies use a current and voltage ripple that exist as parasitic effects in the power stage of an inverter. A power supply based on the output