Bidirectional battery power inverter

Abstract

Disclosed is a bi-directional battery power inverter ( 1 ) comprising a DC-DC converter circuit element ( 3 ) to which the battery ( 2 ) can be connected in order to generate an AC output voltage from a battery ( 2 ) voltage in a discharging mode while charging the battery ( 2 ) in a charging mode. The inverter ( 1 ) further comprises an HF transformer which forms a resonant circuit along with a resonant capacitor ( 6 ). In order to increase the efficiency of said battery power inverter, the transformer is provided with two windings ( 11, 12 ) with a center tap ( 20 ) on the primary side, said center tap ( 20 ) being connected to a power electronic center-tap connection with semiconductor switches ( 21, 31 ) while a winding ( 13 ) to which the resonant capacitor ( 6 ) is serially connected provided on the secondary side.

I claim: 
     
       1. A bidirectional battery power inverter with a DC-DC converter circuit element, to which a battery may be connected, for generating an AC output voltage from a battery DC voltage of the battery in a discharge mode of operation and for charging the battery generating an DC output voltage from an AC voltage in a charge mode of operation, said the power inverter including comprising:
 a DC-DC converter circuit element comprising a resonant circuit comprising an HF transformer that forms a resonant circuit together with and a resonant capacitor, 
 characterized in 
 that wherein the HF transformer comprises two primary windings with a center tap on its primary side, said the center tap being connected to a power electronic midpoint circuit with semiconductor switches, a secondary winding to which the resonant capacitor is connected in series being provided on the a secondary side,; 
 that a DC-AC converter circuit element is provided which lies disposed on the an output side of the power inverter and comprises;  
 a boost or buck chopper that is connected between the DC-DC converter circuit element and the DC-AC converter circuit element; and 
 that a resonant switching element is being distributed in circuit parts having a staggered clock clocking rate, the a resonant frequency of the alternating voltage a resonant circuit being higher than the a clock frequency of a half-bridge. 
 
     
     
       2. The bidirectional battery power inverter as set forth in  claim 1 , wherein 
 characterized in that the DC-DC converter circuit element comprises a half-bridge. 
 
     
     
       3. The bidirectional battery power inverter as set forth in  claim 1 , wherein 
 characterized in that the transformer is configured to be comprises a planar transformer. 
 
     
     
       4. The bidirectional battery power inverter as set forth in  claim 1 , characterized in that wherein the primary windings of the transformer are only guided about the wound around a transformer core while the secondary winding is guided about wound around the transformer core and about an additional choke core. 
     
     
       5. A bidirectional battery power inverter with a DC-DC converter circuit element, to which a battery may be connected, for generating an AC output voltage from a battery DC voltage of the battery in a discharge mode of operation and for charging the battery generating a DC output voltage from an AC voltage in a charge mode of operation, said the power inverter including comprising:
 a resonant circuit comprising an HF transformer that forms a resonant circuit together with and resonant capacitors, characterized in that wherein the HF transformer comprises two primary windings with a center tap on its primary side, said the center tap being connected to a power electronic midpoint circuit with semiconductor switches, and one wherein the HF transformer further comprises a secondary winding on the a secondary side, said the winding being connected to the resonant capacitors at a convergence point,; 
 that a DC-AC converter circuit element is provided which lies disposed on the an output side of the power inverter and comprises comprising a boost or buck chopper that is connected between the DC-DC converter circuit element and the DC-AC converter circuit element; and 
 that a resonant switching element is distributed in circuit parts having a staggered clock rate. 
 
     
     
       6. The bidirectional battery power inverter as set forth in  claim 5 , characterized in that wherein the DC-DC converter circuit element comprises a half-bridge. 
     
     
       7. The bidirectional battery power inserter as set forth in  claim 5 , characterized in that wherein the transformer is configured to be comprises a planar transformer. 
     
     
       8. The bidirectional battery power inverter as set forth in  claim 5 , characterized in that wherein the primary windings of the transformer are only guided about the wound around a transformer core while the secondary winding is guided about wound around the transformer core and about an additional choke core. 
     
     
       9. A bidirectional battery power inverter for bidirectionally converting electrical power between a DC side and an AC side of the inverter, the DC side being connectable to a battery the inverter comprising:
 a DC/DC converter comprising a power electronic midpoint circuit coupled to a primary winding of an HF transformer, 
 and bridge-connected semiconductor elements coupled to a secondary winding of the HF transformer through a capacitance, 
 wherein the capacitance in conjunction with a leakage inductance of the HF transformer defines a resonant frequency,; and  
 a DC/AC converter connected to the DC/DC converter, the DC/AC converter comprising a boost-buck chopper for avoiding voltage-dropping, so that configured to adjust a voltage to an output nominal voltage is achieved, 
 wherein the power electric midpoint circuit is configured to be operated operate at an operation frequency lower than the resonant frequency in order to allow for a substantially zero current switching of the power electronic midpoint circuit. 
 
     
     
       10. The bidirectional battery power inverter of  claim 9 , wherein the primary winding comprises a center tap being connected to a first battery terminal, and wherein the power electronic midpoint circuit comprises two switches being connected to a second battery terminal. 
     
     
       11. The bidirectional battery power inverter of  claim 9 , wherein the capacitance comprises two capacitors connected in series between connection terminals, and wherein the secondary winding is connected to a midpoint of the two capacitors. 
     
     
       12. The bidirectional battery power inverter of  claim 9 , wherein the DC/DC converter further comprises a second power electronic midpoint circuit coupled to a primary winding of a second HF transformer, and second bridge-connected semiconductor elements coupled to a secondary winding of the second HF transformer through a second capacitance. 
     
     
       13. The bidirectional battery power inverter of  claim 12 , wherein the power electronic midpoint circuit and the second power electronic midpoint circuit are configured to be operated at the same operation frequency by an offset clocking. 
     
     
       14. The bidirectional battery power inverter of  claim 9 , wherein the bridge-connected semiconductor elements are configured to form a half bridge. 
     
     
       15. The bidirectional battery power inverter of  claim 9 , wherein the bridge-connected semiconductor elements are configured to form a full bridge. 
     
     
       16. The bidirectional battery power inverter of  claim 9 , wherein the HF transformer is a planar transformer. 
     
     
       17. The bidirectional battery power inverter of  claim 9 , wherein the primary winding of the HF transformer is only guided about wound around a transformer core, and the secondary winding of the HF transformer is guided about wound around an additional choke core. 
     
     
       18. A bidirectional battery power inverter for bidirectionally converting electrical power between a DC side and an AC side of the inverter, the DC side being connectable to a battery, the inverter comprising:
 a DC/DC converter comprising a first and a second power electronic midpoint circuit coupled to corresponding primary windings of a first HF transformer and a second HF transformer, 
 the DC/DC converter further comprising first and second bridge-connected semiconductor elements coupled to corresponding secondary windings of the first and second HF transformer transformers through corresponding coupling capacitances defining a resonant frequency in conjunction with a leakage inductance of the HF transformer transformers; and  
 a DC/AC converter connected to the DC/DC converter, the DC/AC converter comprising a boost-buck chopper for avoiding voltage-fluctuation, so that an output nominal voltage is achieved,  
 wherein the first and second power electronic midpoint circuit is circuits are configured to be operated at an operation frequency lower than the resonant frequency in order to allow for a substantially zero current switching of the first and second power electronic midpoint circuit achieved circuits, 
 and wherein the coupling capacitances are each formed by two capacitors connected in series, one a tap of each of the secondary windings of each of the first and second HF transformer transformers being connected to midpoints of the corresponding capacitance coupling capacitances. 
 
     
     
       19. A bidirectional DC-DC converter comprising:
 an input comprising a first input terminal and a second input terminal;   an output comprising a first output terminal and a second output terminal;   a power electronic midpoint circuit comprising a first switch and a second switch;   a transformer comprising a primary side and a secondary side, the primary side connected to the power electronic midpoint circuit, wherein a first terminal of the first switch is connected to a first terminal of the primary side of the transformer, wherein a first terminal of the second switch is connected to a second terminal of the primary side of the transformer, wherein a second terminal of the first switch and a second terminal of the second switch are connected to the second input terminal, and wherein the first input terminal is connected to a midpoint terminal of the primary side of the transformer;   a first capacitor, wherein a first terminal of the first capacitor is connected to a first terminal of the secondary side of the transformer;   a bridge circuit comprising four bridge switches, wherein a first terminal of a first bridge switch and a first terminal of a second bridge switch are connected to the first output terminal, wherein a second terminal of a third bridge switch and a second terminal of a fourth bridge switch are connected to the second output terminal, wherein a second terminal of the first bridge switch and a first terminal of a third bridge switch are connected to a second terminal of the first capacitor, and wherein a second terminal of the second bridge switch and a first terminal of the fourth bridge switch are connected to a second terminal of the secondary side of the transformer; and   a boost buck chopper element connected to the first output terminal and the second output terminal,   wherein a capacitance of the first capacitor and a leakage inductance of the transformer defines a resonant frequency, and wherein the bidirectional DC-DC converter is configured to be operated at an operation frequency which is lower than the resonant frequency.   
     
     
       20. The bidirectional DC-DC converter as set forth in claim 19, wherein the primary side of the transformer comprises two windings with a center tap and wherein the secondary side of the transformer comprises a single winding. 
     
     
       21. The bidirectional DC-DC converter as set forth in claim 20, wherein the single winding of the secondary side of the transformer and the first capacitor are connected in series. 
     
     
       22. The bidirectional DC-DC converter as set forth in claim 19, further comprising a second capacitor, wherein a first terminal of the second capacitor is connected to the first output terminal, and wherein a second terminal of the second capacitor is connected to the second output terminal. 
     
     
       23. A device for bidirectionally converting electrical power between a first side and a second side comprising:
 a DC-DC converter element comprising
 a midpoint circuit configured to convert a first DC voltage to a first AC voltage and further configured to provide the first AC voltage to a transformer, the midpoint circuit connected to a primary side of the transformer, the primary side comprises two windings with a center tap and the midpoint circuit comprising two switches; 
 a bridge circuit connected to a secondary side of the transformer, the bridge circuit configured to convert a transformed first AC voltage to a second DC voltage, the bridge circuit comprising a capacitor connected to a winding of the secondary side of the transformer; and 
   a boost-buck chopper element connected to the DC-DC converter element,   wherein a capacitance of the capacitor and a leakage inductance of the transformer defines a resonant frequency, and wherein the DC-DC converter element is configured to be operated at an operation frequency which is lower than the resonant frequency.   
     
     
       24. The device as set forth in claim 23, wherein the bridge circuit comprises a full bridge connected through the capacitor to the winding of the secondary side. 
     
     
       25. The device as set forth in claim 23, wherein the bridge circuit comprises a half bridge and a resonant capacitor circuit. 
     
     
       26. The device as set forth in claim 23, wherein the two switches of the midpoint circuit are configured to be switched on and off with zero current. 
     
     
       27. The device as set forth in claim 23, wherein the boost-buck chopper element comprising a choke and a further capacitor. 
     
     
       28. The device as set forth in claim 23, wherein boost-buck chopper element is configured to adapt a variable first AC voltage to a constant DC voltage. 
     
     
       29. The device as set forth in claim 23, further comprising a DC-AC inverter element connected to the boost-buck chopper. 
     
     
       30. A bidirectional DC-DC converter comprising:
 an input comprising a first input terminal and a second input terminal;   an output comprising a first output terminal and a second output terminal;   a first power electronic midpoint circuit comprising a first switch and a second switch;   a first transformer comprising a primary side and a secondary side, the primary side connected to the first power electronic midpoint circuit, wherein a first terminal of the first switch of the first power electronic midpoint circuit is connected to a first terminal of the primary side of the first transformer, wherein a first terminal of the second switch of the first power electronic midpoint circuit is connected to a second terminal of the primary side of the first transformer, wherein a second terminal of the first switch of the first power electronic midpoint circuit and a second terminal of the second switch of the first power electronic midpoint circuit are connected to the second input terminal, and wherein the first input terminal is connected to a midpoint terminal of the primary side of the first transformer;   a circuit comprising switches and capacitors, wherein a first terminal of a first switch of the circuit and a first terminal of a first capacitor of the circuit are connected to the first output terminal, wherein a second terminal of a second switch of the circuit and a second terminal of a second capacitor of the circuit are connected to the second output terminal, wherein a second terminal of the first switch of the circuit and a first terminal of the second switch of the circuit are connected to a first terminal of the secondary side of the first transformer, and wherein a second terminal of the first capacitor of the circuit and a first terminal of the second capacitor of the circuit are connected to a second terminal of the secondary side of the first transformer; and   a boost buck chopper element connected to the first output terminal and the second output terminal.   
     
     
       31. The bidirectional DC-DC converter as set forth in claim 30, wherein the primary side of the first transformer comprises two windings with a center tap and wherein the secondary side of the first transformer comprises a single winding. 
     
     
       32. The bidirectional DC-DC converter as set forth in claim 30, further comprising a filter capacitor, wherein a first terminal of the filter capacitor is connected to the first output terminal, and wherein a second terminal of the filter capacitor is connected to the second output terminal. 
     
     
       33. A bidirectional device comprising:
 a DC-DC converter element comprising:
 an input comprising a first input terminal and a second input terminal; 
 an output comprising a first output terminal and a second output terminal; 
 a first power electronic midpoint circuit comprising a first switch and a second switch; 
 a first transformer comprising a primary side and a secondary side, the primary side connected to the first power electronic midpoint circuit, wherein a first terminal of the first switch of the first power electronic midpoint circuit is connected to a first terminal of the primary side of the first transformer, wherein a first terminal of the second switch of the first power electronic midpoint circuit is connected to a second terminal of the primary side of the first transformer, wherein a second terminal of the first switch of the first power electronic midpoint circuit and a second terminal of the second switch of the first power electronic midpoint circuit are connected to the second input terminal, and wherein the first input terminal is connected to a midpoint terminal of the primary side of the first transformer; 
   a second power electronic midpoint circuit comprising a first switch and a second switch;   a second transformer comprising a primary side and a secondary side, the primary side connected to the second power electronic midpoint circuit, wherein a first terminal of the first switch of the second power electronic midpoint circuit is connected to a first terminal of the primary side of the second transformer, wherein a first terminal of the second switch of the second power electronic midpoint circuit is connected to a second terminal of the primary side of the second transformer, wherein a second terminal of the first switch of the second power electronic midpoint circuit and a second terminal of the second switch of the second power electronic midpoint circuit are connected to the second input terminal, and wherein the first input terminal is connected to a midpoint terminal of the primary side of the second transformer;   a circuit comprising switches and capacitors, wherein a first terminal of a first switch of the circuit and a first terminal of a first capacitor of the circuit are connected to the first output terminal, wherein a second terminal of a second switch of the circuit and a second terminal of a second capacitor of the circuit are connected to the second output terminal, wherein a second terminal of the first switch of the circuit and a first terminal of the second switch of the circuit are connected to a first terminal of the secondary side of the first transformer through a first resonant capacitor, wherein a second terminal of the first capacitor of the circuit and a first terminal of the second capacitor of the circuit are connected to a second terminal of the secondary side of the first transformer, wherein a first terminal of a third switch of the circuit is connected to the first output terminal and a second terminal of a fourth switch is connected to the second output terminal, wherein a second terminal of the third switch of the circuit and a first terminal of the fourth switch of the circuit are connected to a first terminal of the secondary side of the second transformer through a second resonant capacitor, and wherein the second terminal of the first capacitor of the circuit and the first terminal of the second capacitor of the circuit are connected to a second terminal of the secondary side of the second transformer, and wherein the first and second power electronic midpoint circuits are configured to be operated at an operation frequency which is lower than a resonant frequency; and   a boost-buck chopper element connected to the first output terminal and the second output terminal of the DC-DC converter element, the boost-buck chopper configured to avoid voltage fluctuations.   
     
     
       34. The bidirectional device as set forth in claim 33, further comprising a DC-AC inverter element connected to the boost-buck chopper. 
     
     
       35. A device comprising:
 a bidirectional DC-DC converter including a resonant circuit comprising a transformer and resonant capacitors, wherein the transformer comprises a primary side with a center tap, the center tap being connected to a power electronic midpoint circuit comprising semiconductor switches, and wherein the transformer further comprises a secondary winding on a secondary side, the secondary winding being connected to the resonant capacitors at a convergence point; and   a boost or buck chopper connected to the DC-DC converter.   
     
     
       36. The device as set forth in claim 35, further comprising a half-bridge circuit.