NOVELTY - A generating circuit (30) generates phase difference voltage related to phase difference of single phase AC output voltage of AC terminal (22) and internal electromotive voltage of single phase voltage type AC-DC converting circuit (40) based on delay single phase AC, based on which high-order command vector containing voltage amplitude and frequency command values is input. A detector (220) detects variation in frequency of single phase AC output by single phase voltage type AC-DC converting circuit, to stop output of single phase AC electric power from AC terminal.    USE - Single phase voltage type AC-DC converter for utility-interconnected apparatus of electric power system. Can also be used in inverter for photovoltaic power generation, inverter for fuel cell, inverter for electrical storage system, inverter for wind-powered electricity generation, etc., and for single-phase three-wire inverter.    ADVANTAGE - A single phase voltage type AC-DC converter that reliably detects individual operation can be easily provided, when autonomous parallel running of several apparatuses is performed, by detecting variation in frequency of single phase AC output by single phase voltage type AC-DC converting circuit, to stop output of single phase AC electric power from AC terminal. Stable control of single phase voltage type AC-DC converter can be easily achieved, and fault output can be prevented, as the pulse width modulation (PWM) component is removed from the output voltage of single phase voltage type AC-DC converter, while achieving stable feedback loop. The transient variation of output voltage at the time of starting of single phase voltage type AC-DC converter can be suppressed.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram of the single phase voltage type AC-DC converter. (Drawing includes non-English language text)    Single phase voltage type AC-DC converter (11)    AC terminal (22)    Phase difference generating circuit (30)    Single phase voltage type AC-DC converting circuit (40)    Frequency-variation detector (220)