For storing high power, we need high DC storage bulky passive components which are not economical and efficient as losses also increase for converting AC to DC and DC to AC process. However, the AC to AC converters with a DC link is not recommended for high-power ratings as the DC link passive component required capacity increases with the increase in power rating. The diode bridges are preferred for the low load as the AC line distortion and low power factor caused by the Diode Bridge are lesser than the Thyristor Bridge. In this type of converter, the DC link consists of a shunt capacitor and the rectifier consists of a diode bridge. Current Source Inverter Converter Voltage Source Inverter Converter The rectifier used here is a phase-controlled switching device like Thyristor Bridge.
AC DC POWER CONVERTER SERIES
In this type of inverter, one or two series inductors are used between one or both limbs of the connection between the rectifier and inverter. AC to AC converter circuit with a DC link is shown in the figure.ĪC to AC converters with a DC link is classified into two types: Current Source Inverter Converter After being converted into DC, the DC link is used to store DC power, and then again it is converted into AC by using the inverter. AC to AC Converters with a DC LinkĪC to AC converters with a DC link generally consists of a rectifier, DC link, and inverter as in this process the AC is converted into DC by using the rectifier. Both can be varied by varying the firing angle of the converter. Phase controlled Cycloconvertersīy using this type of Cycloconverters, we can change the magnitude of the output voltage in addition to the frequency of the output. Similarly, for a negative converter, the firing angle is set to α=180°, during the positive half cycle, and during the negative half cycle, the firing angle is set to α=0°. For a positive converter, the firing angle is set to α=0°, and during the negative half cycle, the firing angle is set to α=180°. In this type of Cycloconverters, the firing angle is fixed for both the positive and negative half-cycles during the positive half cycle. As both the limbs conducting at the same time, there will be a circulating current in the system, and hence, it is called Circulating Current Mode cycloconverter.Ĭlassification of Cycloconverters Based on the Number of Phases of Output VoltageĬlassification of Cycloconverters Based on the Firing Angle of Positive and Negative Limbs Envelope Cycloconverters These Cycloconvertersneed limiting reactor as both the positive limb and the negative limb conduct at a time, and hence a reactor is placed to limit the circulating current. Hence, this is called as Blocking Mode Cycloconverters. These Cycloconverters don’t need any limiting reactor as in this mode only one limb either positive or negative limb conducts at a time, and the other limb is blocked. Classification of Cycloconverters Based on the Mode of Operation: Blocking Mode Cycloconverters The Positivelimb operates during the positive half cycle and the negative limb operates during the negative half cycle.
By switching the positive and negative limb thyristors, we can get variable output frequency that can be step-up or step-down frequency compared to the input frequency.Ĭycloconverters are Classified into Different Types Based on Different CriteriaĬycloconverters consist of two limbs namely Positive limb also called a positive converter and negative limb also called a negative converter. The above figure shows the working principle of a cycloconverter wherein the input wave frequency changed by changing the firing angle applied to the thyristors.
The cost of the DC link required will vary according to the ratings of the supply power being used. Cycloconverters are preferred for avoiding DC links and to avoid many stages like AC to DC to AC which is not economical and causes more losses.
The AC to AC converters can be classified into different types:Ĭycloconverters are majorly called as frequency changers that convert the AC power with one input frequency to AC power with a different output frequency and can be used for changing the magnitude of the AC power also. For obtaining a desired AC power supply from the actual power supply, we need some converters called AC to AC converters. For speed control of induction motors, AC to AC converters (Cycloconverters) is used majorly. We require a particular voltage and particular frequency for operating some special devices or machines. AC to AC Converter What is AC to AC Converter?
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