Apparatus and method for power conversion

Abstract

A power converting apparatus includes a rectifying circuit having a pair of AC power input terminals and a pair of rectified voltage output terminals; a reactor; and a charging and discharging circuit connected between the rectified voltage output terminals. The charging and discharging circuit includes a first condenser connected with one of the rectified voltage output terminals and one of the AC power input terminals; and a second condenser connected with the other of the rectified voltage output terminals and the one AC power input terminal. The reactor generates a resonance current together with the first condenser and the second condenser, and the second condenser discharges to zero voltage while the first condenser is charged.

1 . A power converting apparatus comprising: 
 a rectifying circuit having a pair of AC power input terminals and a pair of rectified voltage output terminals;    a reactor; and    a charging and discharging circuit connected between said rectified voltage output terminals,    wherein said charging and discharging circuit comprises:    a first condenser connected with one of said rectified voltage output terminals and one of said AC power input terminals; and    a second condenser connected with the other of said rectified voltage output terminals and said one AC power input terminal,    said reactor generates a resonance current together with said first condenser and said second condenser, and    said second condenser discharges to zero voltage while said first condenser is charged.    
   
   
       2 . The power converting apparatus according to  claim 1 , wherein a maximum value of a current flowing from one of said first condenser and said second condenser to said one AC input terminal at a rated operation is substantially same as a maximum value of a rated input current.  
   
   
       3 . The power converting apparatus according to  claim 1 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.  
   
   
       4 . The power converting apparatus according to  claim 1 , wherein when a rated impedance is determined as a value obtained by dividing a second power of rated power by rated voltage, a square root of a value obtained by dividing said inductance by said capacitance is in a range of 0.7 times to 1.2 times of said rated impedance.  
   
   
       5 . The power converting apparatus according to  claim 2 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.  
   
   
       6 . The power converting apparatus according to  claim 2 , wherein when a rated impedance is determined as a value obtained by dividing a second power of rated power by rated voltage, a square root of a value obtained by dividing said inductance by said capacitance is in a range of 0.7 times to 1.2 times of said rated impedance.  
   
   
       7 . A power converting apparatus comprising: 
 a rectifying circuit having a pair of AC power input terminals and a pair of rectified voltage output terminals;    a reactor; and    a charging and discharging circuit connected between said rectified voltage output terminals,    wherein said charging and discharging circuit comprises:    a first charging and discharging circuit connected with one of said rectified voltage output terminals and one of said AC power input terminals; and    a second charging and discharging circuit connected with the other of said rectified voltage output terminals and said one AC power input terminal,    said first charging and discharging circuit comprises a first diode and a first condenser connected with said first diode in series,    said second charging and discharging circuit comprises a second diode and a second condenser connected with said second diode in series, and    said charging and discharging circuit further comprises:    a switch section connected in parallel with a series connection of said first and second diodes,    said reactor generates a resonance current together with said first condenser and said second condenser, and    said second condenser discharges to zero voltage while said first condenser is charged.    
   
   
       8 . The power converting apparatus according to  claim 7 , wherein said switch section comprises two switches which are connected in parallel with said first and second diodes, respectively.  
   
   
       9 . The power converting apparatus according to  claim 7 , wherein said switch comprises a switching element.  
   
   
       10 . The power converting apparatus according to  claim 8 , wherein each of said switches comprises a switching element.  
   
   
       11 . The power converting apparatus according to  claim 7 , wherein a maximum value of a current flowing from one of said first condenser and said second condenser to said one AC input terminal at a rated operation is substantially same as a maximum value of a rated input current.  
   
   
       12 . The power converting apparatus according to  claim 7 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.  
   
   
       13 . The power converting apparatus according to  claim 7 , wherein when a rated impedance is determined as a value obtained by dividing a second power of rated power by rated voltage, a square root of a value obtained by dividing said inductance by said capacitance is in a range of 0.7 times to 1.2 times of said rated impedance.  
   
   
       14 . The power converting apparatus according to  claim 8 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.  
   
   
       15 . The power converting apparatus according to  claim 8 , wherein when a rated impedance is determined as a value obtained by dividing a second power of rated power by rated voltage, a square root of a value obtained by dividing said inductance by said capacitance is in a range of 0.7 times to 1.2 times of said rated impedance.  
   
   
       16 . The power converting apparatus according to  claim 9 , further a drive circuit which comprises: 
 a parallel circuit provided between a gate of said switching element and a control circuit, and    said parallel circuit comprises:    a resistor circuit having a higher resistance; and    a series circuit connected in parallel to said resistor circuit and comprising a resistor having a lower resistance, and a diode connected with said resistor to block off a gate current on charging of said gate.    
   
   
       17 . The power converting apparatus according to  claim 9 , wherein said switching element receives, at a gate thereof, a voltage from a control power supply of said power converting apparatus through a resistor and a diode.  
   
   
       18 . The power converting apparatus according to  claim 7 , wherein said first and second condensers discharge to zero voltage once for one period of said AC power.  
   
   
       19 . The power converting apparatus according to  claim 1 , further comprising: 
 mechanical switches provided between a common node and said first condenser and between said common node and said second condenser.    
   
   
       20 . A power converting apparatus comprising: 
 a rectifying circuit having a pair of AC power input terminals and a pair of rectified voltage output terminals;    a reactor; and    a charging and discharging circuit connected between said rectified voltage output terminals,    wherein said charging and discharging circuit comprises:    a first charging and discharging circuit connected with one of said rectified voltage output terminals and one of said AC power input terminals; and    a second charging and discharging circuit connected with the other of said rectified voltage output terminals and said one AC power input terminal,    said first charging and discharging circuit comprises a first switch and a first condenser connected with said first switch in series,    said second charging and discharging circuit comprises a second switch and a second condenser connected with said second switch in series,    said reactor generates a resonance current together with said first condenser and said second condenser, and    said second condenser discharges to zero voltage while said first condenser is charged.    
   
   
       21 . The power converting apparatus according to  claim 20 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.  
   
   
       22 . A power converting method comprising: 
 connecting a rectifying circuit with an AC power supply;    charging a first charging and discharging section which is connected between a first output terminal as one of two first output terminals of said rectifying circuit and one of two AC power input terminals of said rectifying circuit;    discharging from a second charging and discharging section which is connected between a second output terminal as the other of the two first output terminals of said rectifying circuit and said one AC power input terminal in synchronization with said charging;    charging said second charging and discharging section after a half period of said first charging and discharging period;    discharging said first charging and discharging section in synchronization with said charging said second charging and discharging section;    continuing to connect a terminal of said first charging and discharging section on a side of said AC electric power input terminals and a terminal of said second charging and discharging section on a side of said AC electric power input terminals during a rated operation; and    intermittently opening the terminal of said first charging and discharging section on the side of said AC electric power input terminals and the terminal of said second charging and discharging section on the side of said AC electric power input terminals during a low load operation.    
   
   
       23 . The power converting method according to  claim 22 , wherein said first charging and discharging section and said second charging and discharging section have condensers, respectively, 
 a reactor is provided between said AC electrode input terminal and said rectifying circuit or between said rectifying circuit and said first charging and discharging section, and    a maximum value of a current flowing from one of said first condenser and said second condenser to said one AC input terminal at a rated operation is substantially same as a maximum value of a rated input current.    
   
   
       24 . The power converting method according to  claim 22 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.  
   
   
       25 . The power converting method according to  claim 22 , said first charging and discharging section and said second charging and discharging section have condensers, respectively, 
 a reactor is provided between said AC electrode input terminal and said rectifying circuit or between said rectifying circuit and said first charging and discharging section,    a charging period of one of said first and second condensers and a discharging period of the other condenser are synchronized with each other, and    said one condenser discharges to zero voltage after being charged.    
   
   
       26 . The power converting method according to  claim 25 , wherein capacitances of said first condenser and said second condenser and an inductance of said reactor are determined such that a resonance frequency is in a range of 3 times to 5 times of a frequency of AC power supplied to said AC power input terminals.