Single-phase converter series SIRIO AC and ACS

SIRIO AC and ACS single-phase converters are totally isolated from the mains:

  • AC-MCF model by optoisolated reference
  • AC model with firing pulses sent to the gate via transformer, auxiliary power supplies obtained through a transformer complete with rectifiers and stabilizers

    ac/ac converters

  • ACS model besides the properties of the AC model, has voltage feedback via transformer and a current feedback via current transformer

Since the wave form is symmetrically split both into positive and negative halfwave, the output voltage average value is not affected and equal to zero. This means that three-phase loads can be fed without generating inside the mesh a circulating current with average value other than zero.


icona pdf

Download the ACS series features



icona pdf

Download the AC-MCF series features

SIRIO 3PH and ALFA 3PHSAP three-phase converters

SIRIO 3PH and ALFA 3PHSAP three-phase converters are suitable to control resistive and inductive loads, which require a linear or ON/OFF voltage variation applied to the load.

For SIRIO 3PH models voltage is directly proportional to the reference signal, while the load current depends on the voltage applied to the load and its impedance.

ac/ac converters

For ALFA 3PHSAP models voltage and current depend on the control signals and feedback signals since there are stabilizing rings both for voltage and current.

ac/ac converters

Three-phase converters are mass-produced in the compact series, in a current range between 25A and 600A.

For higher current solutions, electronics and power are separated.


Download the 3PH and 3PHSAP series features icona pdf

ENERGY SAVING square wave static converters

The ENERGY SAVING static converter serves to generate a controlled squarewave single-phase alternate voltage (low frequency: 25 ÷125Hz) for industrial applications requiring high load power supplied by an external matching transformer. The power supply, sectioned by remote control switch and external fuses, is fed by a three-phase electric line via uncontrolled diode bridge and filtered by inductor and capacitor battery. The DC voltage thus obtained is converted into single-phase alternating voltage via “H”-shape bridge of semiconductors in order to control impressed frequency single-phase transformers.

The IGBT (Insulated Gate Bipolar Transistor) technology provides an extremely efficiency control of high powers.
The benefits offered by this converters are:
  •  Reliability and efficiency typical of semiconductor devices
  • High output (about 95%) and the possibility to control high power loads
  • Power factor cos(φ) = 0.9, that is no need of power factor correction
  • Power taken from the line on each phase in a balanced way
  • Simple water cooling system
The control and the machine cycles management are regularly entrusted to an external PLC.

The electric energy saving with respect to the SRC three-phase machines can reach the 47,6%.

ac/ac converters

Square wave inverter

Application examples

This project constitutes a reliable solution for controlling high powers for sintering of graphite moulds in machines for the production of diamond tools. The sintering process of diamond segments takes place in a controlled atmosphere through the passage of a strong electric current that, by Joule effect, increases their temperature to over 2000°C. Therefore, the power structure proposed is used to control a transformer similar to the one for welding, that is a single secondary turn that allows achieving currents of even 50 kA.

ac/ac converters

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