Single-stage bidirectional DC converter and single-phase user-side energy storage inverter based on single-stage bidirectional DC converter

1 . A single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter, comprising a single-stage bidirectional DC and an inverter circuit connected to the single-stage bidirectional DC converter,

wherein the single-stage bidirectional DC converter is used for bidirectional charge and discharge of a battery, and comprises a transformer T 1 , a bus-side circuit, a battery-side circuit and a controller, wherein the bus-side circuit is electrically connected to a primary side of the transformer T 1 , and the battery-side circuit is electrically connected to a secondary side of the transformer T 1 ;

the bus-side circuit comprises at least one energy storage branch, each said energy storage branch comprises a bus-side switching transistor, the battery-side circuit comprises a battery-side switching transistor, the controller is used for controlling on/off of the bus-side switching transistor and the battery-side switching transistor, and the battery-side switching transistor and the bus-side switching transistor are turned on and off complementarily,

wherein the bus-side circuit of the single-stage bidirectional DC converter comprises two energy storage branches, and the two energy storage branches are respectively connected to a positive terminal VBUS+ of the DC bus and a negative terminal VBUS− of the DC bus;

each said energy storage branch comprises a bus-side switching transistor, the battery-side circuit comprises a battery-side switching transistor, the controller is used for controlling on/off of the bus-side switching transistors and the battery-side switching transistor, the bus-side switching transistors are turned on and off synchronously, and the battery-side switching transistor and the bus-side switching transistors are turned on and off complementarily,

wherein the two energy storage branches are a first energy storage branch and a second energy storage branch respectively, the first energy storage branch and the second energy storage branch are respectively connected to the dotted terminal and the undotted terminal of the primary winding of the transformer T 1 , and a center tap of the primary winding of the transformer T 1 is grounded; the first energy storage branch comprises an inductor L 1 _A, a third capacitor C 3 and a first switching transistor Q 1 , and the second energy storage branch comprises an inductor L 1 _B, a fourth capacitor C 4 and a second switching transistor Q 2 ;

the inductor L 1 _A and the third capacitor C 3 are connected in series and then connected between the dotted terminal of the primary winding of the transformer T 1 and the positive terminal VBUS+ of the DC bus, a drain of the first switching transistor Q 1 is connected to a midpoint between the inductor L 1 _A and the third capacitor C 3 , and a source of the first switching transistor Q 1 is connected to the center tap of the primary winding of the transformer T 1 and is grounded;

the inductor L 1 _B and the fourth capacitor C 4 are connected in series and then connected between the undotted terminal of the secondary winding of the transformer T 1 and the negative terminal VBUS− of the DC bus, a source of the second switching transistor Q 2 is connected to a midpoint between the inductor L 1 _B and the fourth capacitor C 4 , and a drain of the second switching transistor Q 2 is connected to the center tap of the primary winding of the transformer T 1 and is grounded;

a first capacitor C 1 and a second capacitor C 2 are respectively connected between the positive terminal VBUS+ of the DC bus and the center tap of the primary winding of the transformer T 1 as well as between the negative terminal VBUS− of the DC bus and the center tap of the primary winding of the transformer T 1 .

2 . The single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter according to claim 1 , wherein the battery-side circuit comprises a third switching transistor Q 3 , a drain of the third switching transistor Q 3 is connected to the undotted terminal of the secondary winding of the transformer T 1 , a source of the third switching transistor Q 3 is grounded, the dotted terminal of the secondary winding of the transformer T 1 is connected to the positive terminal VBAT of the battery, and a fifth capacitor C 5 is connected between the dotted terminal of the secondary winding of the transformer T 1 and the ground wire.

3 . The single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter according to claim 1 , wherein the inverter circuit is a single-phase inverter circuit, and the single-phase inverter circuit comprises a switching transistor Q 4 , a switching transistor Q 5 , a switching transistor Q 7 , a switching transistor Q 8 , an inductor L 3 and an inductor L 4 ;

the switching transistor Q 4 , the switching transistor Q 5 , the switching transistor Q 7 and the switching transistor Q 8 form two inverter bridges, which are connected between the positive terminal VBUS+ of the DC bus and the negative terminal VBUS− of the DC bus, and the inductor L 3 and the inductor L 4 are respectively connected between arms of the two inverter bridges and input power lines V_L and V_N.

4 . The single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter according to claim 1 , wherein the inverter circuit is a half-bridge inverter circuit, and the half-bridge inverter circuit comprises a capacitor C 6 , a capacitor C 7 , a switching transistor Q 4 , a switching transistor Q 7 , an inductor L 3 and inductor L 4 ;

the capacitor C 6 and the capacitor C 7 are connected in series and then connected between the positive terminal VBUS+ of the DC bus and the negative terminal VBUS− of the DC bus, the switching transistor Q 4 and the switching transistor Q 7 are connected in series and then connected between the positive terminal VBUS+ of the DC bus and the negative terminal VBUS− of the DC bus, two terminals of the inductor L 4 are respectively connected to a midpoint between the capacitor C 6 and the capacitor C 7 and an input power line V_N, and two terminals of the L 3 are respectively connected to a midpoint between the switching transistor Q 4 and the switching transistor Q 7 and an input power line V_L.

5 . The single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter according to claim 1 , wherein the inverter circuit is a three-phase inverter circuit, and the three-phase inverter circuit comprises a fourth switching transistor Q 4 , a fifth switching transistor Q 5 , a sixth switching transistor Q 6 , a seventh switching transistor Q 7 , an eighth switching transistor Q 8 , a ninth switching transistor Q 9 , a third inductor L 3 , a fourth inductor L 4 and a fifth inductor L 5 ;

the fifth switching transistor Q 5 , the sixth switching transistor Q 6 , the seventh switching transistor Q 7 , the eighth switching transistor Q 8 and the ninth switching transistor Q 9 form three inverter bridges, which are connected in parallel between the positive terminal VBUS+ of the DC bus and the negative terminal VBUS− of the DC bus, and the inductor L 3 , the inductor L 4 and the inductor L 5 are respectively connected between arms of the three inverter bridges and input power lines VA, VB and VC.

6 . The single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter according to claim 1 , wherein the inverter circuit is a three-phase and three-level inverter circuit, the three-phase and three-level inverter circuit comprises three three-level inverter branches which are connected in parallel, and a phase difference between the three three-level inverter branches is 120°; each said three-level inverter branch comprises a T-type three-level inverter, a first inverter inductor and a first output capacitor, the T-type three-level inverter comprises a first switching unit, a second switching unit and a third switching unit which are connected in a T shape, the first switching unit and the second switching unit are connected in series and then connected between the positive terminal VBUS+ of the DC bust and the negative terminal VBUS− of the DC bus, the third switching unit is connected between a center tap of the transformer T 1 and a midpoint between the first switching unit and the second switching unit, the midpoint between the first switching unit and the second switching unit is connected to a first output terminal by means of the first inverter inductor, and a second output terminal is connected to the negative terminal VBUS− of the DC bus;

wherein, the third switching unit comprises a pair of switching transistors which are connected back-to-back;

the first output capacitor is connected between the first output terminal and the second output terminal.

7 . The single-phase user-side energy storage inverter based on a single-stage bidirectional DC converter according to claim 1 , wherein the inverter circuit is a split-phase inverter circuit, the split-phase inverter circuit comprises two split-phase inverter branches which are connected in parallel back-to-back, and a preset phase difference is set between the two split-phase inverter branches; each said split-phase inverter branch comprises a split-phase inverter, a second inverter inductor and a second output capacitor, the split-phase inverter comprises a fourth switching unit, a fifth switching unit and a sixth switching unit which are connected in a T shape, the fourth switching unit and the fifth switching unit are connected in series and then connected between the positive terminal VBUS+ of the DC bus and the negative terminal VBUS− of the DC bus, the sixth switching unit is connected between a center tap of the transformer T 1 and a midpoint between the fourth switching unit and the fifth switching unit, the midpoint between the fourth switching unit and the fifth switching unit is connected to a first output terminal by means of the second inverter inductor, and a second output terminal is connected to the negative terminal VBUS− of the DC bus;

wherein, the sixth switching unit comprises a pair of switching transistors which are connected back-to-back;

the second output capacitor is connected between the first output terminal and the second output terminal.