M C710/AcR - Section: 1. General description of the M C710/AcR frequency converter
1. General description of the MFC710/AcR freq ency converter
The M C710/AcR frequency converter was developed by extending the M C710 frequency converter with an
AcR (Active Rectifier) reversible rectifier module replacing the conventional diode input circuit. This eliminates
the problems arising from the use of diode rectifiers:
• power supply current and voltage distortions caused by the non-linear load,
• no possibility of returning electricity to the mains.
ig. 1.1 shows block diagrams of both types of converters.
MFC710
Fig. 1.1: Blo k diagrams of MFC710 and MFC710/A R onverters
Using the M C710/AcR converter, we obtain:
1. FC power factor correction, limitation of THDi c rrent distortion factor and THD voltage.
The AcR module allows to obtain a sinusoidal waveform of the consumed current, eliminating the
negative impact of higher harmonics introduced into the power supply network when using
conventional power supply systems.
2. Bidirectional power flow, fo r-q adrant operation.
In converter drives, there is often a situation in which the energy accumulated in the load must be
transferred back to the source or lost in the form of heat on an additional resistor. If this process is
intense or repeated often, the use of an additional braking resistor may be unprofitable or impossible.
The AcR module allows bidirectional power flow, so that it can transfer the stored energy to the
mains for recycling. Such a solution is justified not only from the point of view of the energy balance
but also from the point of view of operating costs. The module is used, among others in drive
applications for centrifuges, cranes and the processing of energy obtained from renewable sources.
3. Voltage stabilization in the intermediate circ it.
The AcR module is a three phase AC / DC boost converter. This means that the voltage in the
intermediate circuit of the inverter may be higher than the mains voltage. The use of the AcR module
in the frequency converter allows for higher voltage than the supply voltage at the inverter output
(e.g. 400VAC 50Hz input voltage, 0-500VAC 0-400Hz output voltage).
