ABSTRACT :

In this, Voltage lift technique is used in electronic circuit design. However the voltage increases stage by stage along arithmetic progression. But with a super-lift converter, the output increases stage by stage along a geometric progression. Thus it effectively enhances the transfer gain in power series. This study presents the design of luo converter capable of providing boosted voltage for lower input voltages to drive the bldc motor. The classical buck converter for BLDC motor applications do not meet the load requirement containing more ripples on the output voltage and parasitic effects. In order to overcome this effect, the additional filter elements are added in the Luo-converter to eliminate the output ripples and effectively enhance the output voltage level. The output stage of the Luo converter is comprised of an inductor and capacitor so it naturally acts as filter. The output stage stores and delivers energy to the load and smoothens the output voltage to produce a constant output voltage. The Luo Converter acts as both buck and boost converter by varying the duty cycle. Thus this Luo Converter is used for the proposed BLDC Motor Drive.

INTRODUCTION:

Luo converters are DC-DC Switching Mode Boost converters. A boost converter (step-up converter) is a power converter with an output dc voltage greater than its input dc voltage. Luo converters are a class of converters providing a high gain with relatively lesser number of components. Although Luo converters provide a high gain, when cascaded, the gain increases stage by stage only in Arithmetic Progression i.e. these converters uses the voltage lift (VL) technique. In order to solve this discrepancy in the Classical Luo Converters, another class of converters called Super-lift Luo Converters were developed. While the positive aspects of the Classical Luo Converters are retained in Super-lift converters, Super-lift converters also have the advantage that the gain in this converter increases in geometric progression, stage by stage.

PROBLEM STATEMENT:

A BLDCM drive with PID controller scheme will require a constant DC supply based VSI with Pulse Width Modulated (PWM) scheme for speed control. The speed of the BLDCM is dependent on the DC voltage measured across the front-end of the inverter, a variable speed operation can be employed by adjusting the DC link voltage of inverter with fundamental frequency switching. A PI controller based speed control loop is used to adjust the dc voltage according to the speed requirement.