Title :
Current-source converter on-line pattern generator switching frequency minimization
Author :
Espinoza, José R. ; Joós, Géza
Author_Institution :
Dept. of Electr. & Comput. Eng., Concordia Univ., Montreal, Que., Canada
fDate :
4/1/1997 12:00:00 AM
Abstract :
On-line pulsewidth modulation (PWM) pattern generators for current-source rectifiers and inverters offer a number of control advantages over off-line optimized patterns. However, when implemented using the principles which apply to voltage-source inverter PWM pattern generators, the switching frequency is equal to: (1) the carrier frequency in standard carrier-based implementations and (2) a function of the cycle frequency, sequence of space vectors, and selection of the zero space vector in space vector implementations. This paper shows that this frequency can be reduced to one-half of the respective frequencies. Two pattern generators are investigated: (1) an analog on-line carrier-based technique, namely, the modified dead-band technique and (2) a digital on-line space vector-based technique, where advantage is taken of the extra zero state available in current-source converters. It is shown that the switching frequency reduction is achieved with no penalty in the line current harmonic distortion. Moreover, a significant reduction of AC line current distortion is obtained with the modified dead-band technique for modulation indexes greater than 0.4. The principles of operation of the proposed schemes are explained, Experimental results on a 5 kVA current-source rectifier and a 5 kVA current-source inverter confirm the feasibility and features of the proposed pattern generators
Keywords :
PWM invertors; PWM power convertors; power system harmonics; rectifying circuits; switching circuits; 5 kVA; analog on-line carrier-based technique; carrier frequency; current-source converter; current-source inverters; current-source rectifiers; cycle frequency; digital on-line space vector-based technique; line current harmonic distortion; modified dead-band technique; modulation indexes; on-line PWM pattern generators; on-line control; on-line pattern generator; space vectors sequence; standard carrier-based implementations; switching frequency minimization; switching frequency reduction; voltage-source inverter PWM pattern generators; Analog-digital conversion; Harmonic distortion; Pulse generation; Pulse inverters; Pulse width modulation inverters; Rectifiers; Space vector pulse width modulation; Switching converters; Switching frequency; Zero voltage switching;
Journal_Title :
Industrial Electronics, IEEE Transactions on