A Direct Single-Phase to Three-Phase AC/AC Power Converter

Abstract

The traditional DC-link indirect AC/AC power converters (AC/DC/AC converters) employ two-stage power conversion, which increases the circuit complexity gate driving challenges, placing an excessive burden on the processor while implementing complex switching modulation techniques and leads to power conversion losses due to the use of a large amount of controlled power semiconductor switches. On the contrary, the traditional direct AC/AC voltage controllers, as well as frequency changers, suffer from high total harmonic distortion (THD) problems. In this paper, a new single-phase to three-phase AC/AC step-down power converter is proposed, which utilizes a multi-linking transformer and bilateral triode thyristors (TRIACs) as power semiconductor switches. The proposed direct AC/AC power converter employs single-stage power conversion, which mitigates the complexity of two-stage DC-link indirect AC/AC converters and traditional single-stage AC/AC frequency changers. Instead of using high-frequency pulse width modulated gate driving signals, line frequency gate pulses are used to trigger the TRIACs of the proposed AC/AC converter, which not only aids in reducing the power loss of the converter but also mitigates the cost and complexity of gate driver circuits. The proposed AC/AC converter reduces the THD of the output voltage significantly as compared to traditional direct AC/AC frequency changers. The performance of the proposed AC/AC converter is validated against RL and induction motor load in terms of overall THD and individual harmonic components through MATLAB/Simulink environment. A reduced-scale laboratory prototype is built and tested to evaluate the performance of the proposed AC/AC power converter. The experimental and simulation outcomes reveal the feasibility and excellent features of the proposed single-phase to three-phase AC/AC converter topology.

Experimental comparison of operational amplifier and voltage sensor-based zero-crossing detector circuits for power electronic converters

“…In [5], a ZCD circuit is utilized to synchronize the voltage source inverter with the grid in a static synchronous compensator system. In [6][7][8][9][10][11], ZCD circuits are used to control and synchronize various topologies of AC-AC converters. In [12][13][14][15][16][17][18], ZCD circuits got involved in various other synchronizing applications.…”

“…They also got involved in frequency and phase angle measurement applications in [3,4]. ZCD circuits are usually built using optocouplers [5,11,19], operational amplifiers (op-amps) [19][20][21][22][23], or voltage sensors [6,10,24,25]. Optocoupler-based ZCD circuits provide the required level of isolation, however, they use diodes that lead to delayed ZCD due to the forward voltage drop.…”