Power conversion apparatus

Abstract

An isolated power conversion apparatus has an isolation transformer, a series circuit including a load and an inductor connected in series with each other, the series circuit being disposed on a secondary side of the isolation transformer, and one or a plurality of switching means disposed between the series circuit and the secondary side of the isolation transformer, the switching means being bidirectional. This apparatus sends out power from a DC power supply of a primary side of the isolation transformer toward the load as DC power or AC power of an arbitrary polarity, or regenerates and supplies the DC power or AC power from the load to the DC power supply.

1 . An isolated power conversion apparatus having an isolation transformer, the apparatus comprising:
 a first switching means disposed between a DC power supply and a primary side of the isolation transformer, the first switching means driving the primary side of the isolation transformer in a forward direction;   a second switching means disposed between the DC power supply and the primary side of the isolation transformer, the second switching means driving the primary side of the isolation transformer in a reverse direction;   a series circuit including a load and an inductor connected in series with each other, the series circuit being disposed on a secondary side of the isolation transformer; and   one or a plurality of fourth switching means disposed between the series circuit and the secondary side of the isolation transformer, the fourth switching means being bidirectional, wherein   the isolated power conversion apparatus sends out power from the DC power supply toward the load as DC power or AC power of an arbitrary polarity, or regenerates and supplies the DC power or AC power from the load to the DC power supply.   
     
     
         2 . The isolated power conversion apparatus of  claim 1 , further comprising one or a plurality of third switching means disposed in parallel with the series circuit, the third switching means being bidirectional. 
     
     
         3 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolation transformer has a first and a second primary coils connected in series with each other, the first primary coil being connected to one end of the first switching means and the second primary coil being connected to one end of the second switching means, another end of each of the first switching means and the second switching means being connected to a common connection point.   
     
     
         4 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolation transformer has a primary coil, one end of the primary coil being connected to the DC power supply via the first switching means and the second switching means, and   another end of the primary coil is connected to the DC power supply via a capacitor or to a point between two DC power supplies.   
     
     
         5 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolation transformer has a primary coil, and wherein   the first switching means includes at least two switching elements,   the second switching means includes at least two switching elements, and   a bridge circuit is made up of the switching elements of the first switching means and the switching elements of the second switching means, the bridge circuit being connected to the primary coil.   
     
     
         6 . The isolated power conversion apparatus of  claim 1 , wherein
 either the first switching means or the second switching means or both the first and second switching means includes a field-effect transistor (MOS-FET), a junction field-effect transistor (J-FET), a bipolar transistor, or an insulated gate bipolar transistor (IGBT).   
     
     
         7 . The isolated power conversion apparatus of  claim 1 , wherein
 one or a plurality of the first switching means, the second switching means and the fourth switching means has a diode in parallel, the diode being a diode element connected to the switching means, a diode built in the switching means, or a parasitic diode.   
     
     
         8 . The isolated power conversion apparatus of  claim 2 , wherein
 the third switching means has a diode in parallel, the diode being a diode element connected to the switching means, a diode built in the switching means, or a parasitic diode.   
     
     
         9 . The isolated power conversion apparatus of  claim 2 , wherein
 the third switching means includes two unidirectional switching elements connected in directions opposite to each other.   
     
     
         10 . The isolated power conversion apparatus of  claim 1 , wherein
 the fourth switching means includes two unidirectional switching elements connected in directions opposite to each other.   
     
     
         11 . The isolated power conversion apparatus of  claim 2 , wherein
 the third switching means includes
 a diode bridge and 
 a unidirectional switching element connected between a connection point, to which anodes of diodes making up the diode bridge are connected, and a connection point, to which cathodes of the diodes making up the diode bridge are connected. 
   
     
     
         12 . The isolated power conversion apparatus of  claim 1 , wherein
 the fourth switching means includes
 a diode bridge and 
 a unidirectional switching element connected between a connection point, to which anodes of diodes making up the diode bridge are connected, and a connection point, to which cathodes of the diodes making up the diode bridge are connected. 
   
     
     
         13 . The isolated power conversion apparatus of  claim 2 , wherein
 the third switching means includes any of a MOS-FET, a J-FET, a bipolar transistor, an IGBT, and a bidirectional switching element.   
     
     
         14 . The isolated power conversion apparatus of  claim 1 , wherein
 the fourth switching means includes any of a MOS-FET, a J-FET, a bipolar transistor, an IGBT, and a bidirectional switching element.   
     
     
         15 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolation transformer has one or a plurality of separate coils on its secondary side, said one or each separate coil being provided with a rectifying means and a smoothing means, and   said one or each separate coil, the rectifying means and the smoothing means serve as an isolated DC power source.   
     
     
         16 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolated power conversion apparatus outputs power by multi-phase output, and   wherein power is output at each phase in the multi-phase output from a separate secondary coil of the isolation transformer for each phase or from a common secondary coil of the isolation transformer.   
     
     
         17 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolated power conversion apparatus outputs power by two-phase output,   a waveform equivalent to a waveform generated by comparing an absolute value of an input waveform with a sawtooth wave is used as a drive waveform for the switching element at one phase in the two-phase output, and   a waveform equivalent to a waveform generated by comparing the absolute value of the input waveform with a reverse sawtooth wave is used as a drive waveform for the switching element at the other phase in the two-phase output.   
     
     
         18 . The isolated power conversion apparatus of  claim 1 , wherein
 the isolated power conversion apparatus outputs power by three-phase output,   a waveform equivalent to a waveform generated by comparing an absolute value of an input waveform with a sawtooth wave is used as a drive waveform for the switching element at a first phase in the three-phase output,   a waveform equivalent to a waveform generated by comparing the absolute value of the input waveform with a reverse sawtooth wave is used as a drive waveform for the switching element at a second phase different from the first phase in the three-phase output, and   a waveform equivalent to a waveform generated by comparing the absolute value of the input waveform with a triangular wave is used as a drive waveform for the switching element at a third phase different from the first and second phases in the three-phase output.