FLC-FPGA based Digital Controller for Boost PFC SMPS without Current Measurement Atla Bhaskar M. Tech student: dept. of EEE, NBKRIST Nellore, Andhra Pradesh, India-524413 bhaskarkasthuraiah@gmail.com U Ramesh Babu Asst professor: dept. of EEE, NBKRIST Nellore, Andhra Pradesh, India-524413 uramesh25@gmail.com Abstract—Diode based bridge rectifiers (AC to DC power converters) are the widely used power supplies. The major drawbacks of the conventional diode bridge rectifiers and thyristor-based rectifiers (nonlinear loads) are low power factor and high current harmonics in AC supply. This paper presents the design of a digital controller for continuous conduction mode boost converter with power factor correction on Xilinx FPGA. It is designed to minimize or reduce input current harmonic distortion by reducing the total harmonic distortion (THD) and improving the power factor of power supplies. The pre-calculated duty cycle control is implemented in FPGA for power factor correction in order to avoid the costly and complex process of current measurement. To obtain stable output voltages even in the presence of uncertainties (load variations) and disturbances (input voltage variations) a voltage loop with a fuzzy logic controller is included. Keywords—boost Converter; field programmable gate array (FPGA); fuzzy logic controller (FLC); power factor correction (PFC); switched-mode power supply(SMPS); zero crossing detector (ZCD). I. INTRODUCTION The usage of power electronic devices such as desktops, VFDs, monitors, servers, and photocopiers increases day by day. These devices are mostly powered by switch- mode power supplies (SMPSs). Switch mode power supplies have been growing at a faster rate for several applications such as communications, computers, instrumentation industrial controls and military/aerospace due to the advantages of smaller size, lesser weight, and high efficiency. A conventional switch-mode power supply (SMPS) employs a diode rectifier for AC to DC power conversion. The main drawbacks of diode bridge rectifiers (Nonlinear loads) are high harmonic distortion in source current, poor power factor and low efficiency. So these nonlinear loads will increase the electromagnetic interference (EMI), require over- dimensioning of parts and reduce the maximum power capability of the line [1]. In order to reduce above-mentioned impacts on the line and to improve the power quality various power factor correction (PFC) schemes have been proposed [2]. According to regulation norms IEC 1000-3-2, active power factor correction (APFC) is mostly preferred over passive power factor correction nowadays [3]. Inactive power factor correction approach, a DC to DC controlled converter is placed between bridge rectifier and the load which tries to maintain the constant DC output bus voltage and draws a current that is in phase with and at the same frequency as the line voltage [4]. A detailed study of PFC topologies for industrial applications has been presented in [5]. Boost power factor correction topology has been widely integrated to AC to DC power converters in order to achieve the derived power factor correction and harmonic reduction because boost converter can draw continuous current from the input supply [6-7]. The digital control has many advantages with respect to analog control such as increased reliability, reproducibility of the system, complex algorithms, lower noise sensitivity and easy signal monitoring. The advancement in field programmable gate arrays (FPGAs), microprocessors (μPs), microcontrollers (μCs) and digital signal processors (DSPs) technologies, resulted in the expansion of the processing capacity, design flexibility, easiness of system integration and cost reduction. So the digital control is becoming more suitable for applications in power converters operating at high frequency over analog control. However, all the existing digital control methods are based on conventional analog control laws in digital format [8-9]. FPGA control of boost PFC, based on conventional average current mode control was illustrated in [10]. FPGA is more user-friendly than all other controller systems in recent days, which can perform any logic function such as digital interface, controllers, numeric processors and decoders in a single IC by software programming. Two main characteristics of FPGAs are great versatility and capacity of executing different tasks in parallel. These characteristics give FPGAs a great advantage over DSPs in some of the applications on power electronics and power factor correction converters. Recently there are some researches on digital control of AC to DC converters based on FPGAs [11-12]. A predictive control algorithm for boost PFC converter was presented in [13]. The control in power factor correction typically done with two loops; an internal and fast current loop to achieve near unity power factor and an external and slow voltage loop to stabilize the output voltage in this case three measurements are necessary; input and output voltages ( and respectively), and input current ( ). This work was financially supported by Research and Development Cell, NBKR Institute of Science and Technology, Vidyanagar, SPSR Nellore District, Andhra Pradesh, India-524413. Authors acknowledge the NBKRIST and thank for the encouragement in carrying out the experimental work.