Bidirectional battery power inverter

• US 20080094860A1
• Filed: 10/23/2007
• Published: 04/24/2008
• Est. Priority Date: 05/20/2005
• Status: Active Grant

• Current Assignee: SMA Solar Technology AG
• Original Assignee: SMA Technologie AG (SMA Solar Technology AG)
• Inventors: Falk, Andreas
• Granted Patent: US 7,746,669 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/3372 of the parallel type
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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.

Claims

1. A bidirectional battery power inverter (1) with a DC-DC converter circuit element (3), to which a battery (2) may be connected, for generating an AC output voltage from a battery voltage of the battery (2) in a discharge mode of operation and for charging the battery (2) in a charge mode of operation, said power inverter (1) including an HF transformer that forms a resonant circuit together with a resonant capacitor (6),

characterized in

that the transformer comprises two windings (11, 12) with a center tap (20) on its primary side, said center tap being connected to a power electronic midpoint circuit with semiconductor switches (31), a winding (13) to which the resonant capacitor (6) is connected in series being provided on the secondary side,

that a DC-AC converter circuit element (5) is provided which lies on the output side of the power inverter (1) and comprises a boost or buck chopper (8) that is connected between the DC-DC converter circuit element (3) and the DC-AC converter circuit element (5) and

that a resonant switching element is distributed in circuit parts having a staggered clock rate,

the resonant frequency of the alternating voltage circuit being higher than the clock frequency of a half-bridge.

2. The bidirectional battery power inverter as set forth in claim 1,

characterized in that the DC-DC converter circuit element (3) comprises a half-bridge.

3. The bidirectional battery power inverter as set forth in claim 1,

characterized in that the transformer is configured to be a planar transformer (29).

4. The bidirectional battery power inverter as set forth in claim 1,

characterized in that the primary windings of the transformer are only guided about the transformer core whilst the secondary winding is guided about the transformer core and about an additional choke core (30).

5. A bidirectional battery power inverter (1) with a DC-DC converter circuit element (3), to which a battery (2) may be connected, for generating an AC output voltage from a battery voltage of the battery (2) in a discharge mode of operation and for charging the battery (2) in a charge mode of operation, said power inverter (1) including an HF transformer that forms a resonant circuit together with resonant capacitors (34, 35),

characterized in

that the transformer comprises two windings (11, 12) with a center tap (20) on its primary side, said center tap being connected to a power electronic midpoint circuit with semiconductor switches (21, 31), and one winding (13) on the secondary side, said winding being connected to the resonant capacitors (34, 35) at a convergence point,

that a DC-AC converter circuit element (5) is provided which lies on the output side of the power inverter (1) and comprises a boost or buck chopper (8) that is connected between the DC-DC converter circuit element (3) and the DC-AC converter circuit element (5) 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 the DC-DC converter circuit element (3) comprises a half-bridge.

7. The bidirectional battery power inverter as set forth in claim 5,

characterized in that the transformer is configured to be a planar transformer (29).

8. The bidirectional battery power inverter as set forth in claim 5,

characterized in that the primary windings of the transformer are only guided about the transformer core whilst the secondary winding is guided about the transformer core and about an additional choke core (30).