Battery charging and discharging system based on bidirectional converter

Abstract

The utility model provides a battery charging and discharging system based on a bidirectional converter, which is characterized in that a first direct current input port is connected with one end of a first circuit, the other end of the first circuit is connected with one end of a resonant cavity circuit, and the other end of the resonant cavity circuit is connected with one end of a second circuit; the second direct current input port is connected with the other end of the synchronous rectifier bridge; the second direct current input port is also connected with the three-phase BUCK-BOOST circuit, and the three-phase BUCK-BOOST circuit is connected with the direct current output port; therefore, because the resonant converter and the three-phase BUCK-BOOST converter both have an electric energy bidirectional flow function, the energy storage system of the utility model can realize charging and discharging, so that a set of discharging equipment does not need to be additionally arranged, the space occupation of the equipment is reduced, and the cost can be reduced at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of battery charging and discharging, in particular to a battery charging and discharging system based on a bidirectional converter. Background Art

[0002] With the rapid development of renewable energy technology, energy storage technology has been widely applied.

[0003] However, the current energy storage unit has a single function, such as only being able to perform single charging; if discharging is required, additional discharging equipment needs to be arranged, which not only occupies a large space but also increases the cost.

[0004] Based on this, there is an urgent need for a battery charging and discharging system to solve the above problems in the prior art. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, an embodiment of the utility model provides a battery charging and discharging system based on a bidirectional converter to solve or partially solve the technical problems of the single function of the energy storage unit in the prior art, large occupied space and high cost.

[0006] The utility model provides a battery charging and discharging system based on a bidirectional converter, and the system includes: a bidirectional resonant converter and a three-phase BUCK-BOOST converter; wherein,

[0007] The bidirectional resonant converter includes: a first DC input port, a first circuit, a resonant cavity circuit and a second circuit; the first DC input port is connected to one end of the first circuit, the other end of the first circuit is connected to one end of the resonant cavity circuit, and the other end of the resonant cavity circuit is connected to one end of the second circuit;

[0008] The three-phase BUCK-BOOST converter includes: a second DC input port, a three-phase BUCK-BOOST circuit; the second DC input port is connected to the other end of the synchronous rectifier bridge; the second DC input port is also connected to the three-phase BUCK-BOOST circuit, and the three-phase BUCK-BOOST circuit is connected to the DC output port; wherein, when the system is in the charging mode, the first circuit acts as an inverter bridge circuit, and the second circuit acts as a synchronous rectifier bridge circuit; when the system is in the discharging mode, the first circuit acts as the synchronous rectifier bridge circuit, and the second circuit acts as the inverter bridge circuit.

[0009] In the above solution, the system further includes: a first filter capacitor, a second filter capacitor, a third filter capacitor and a fourth filter capacitor;

[0010] The first filter capacitor is connected to the first DC input port;

[0011] The second filter capacitor is connected to the output terminal of the second circuit;

[0012] The third filter capacitor is connected to the second DC input port;

[0013] The fourth filter capacitor is connected to the DC output port.

[0014] In the above solution, the first circuit includes: a first bridge arm and a second bridge arm;

[0015] The first bridge arm includes a first switching tube and a second switching tube; the source of the first switching tube is connected to the positive pole of the first DC input port, the drain of the first switching tube is connected to the source of the second switching tube, and the drain of the second switching tube is connected to the negative pole of the first DC input port;

[0016] The second bridge arm includes a third switching tube and a fourth switching tube; the source of the third switching tube is connected to the positive pole of the first DC input port, the drain of the third switching tube is connected to the source of the fourth switching tube, and the drain of the fourth switching tube is connected to the negative pole of the first DC input port.

[0017] In the above solution, the resonant cavity circuit includes: a transformer, a primary resonant inductor of the resonant cavity, and a primary resonant capacitor of the resonant cavity; where

[0018] The midpoint of the first bridge arm is connected to one end of the primary resonant inductor of the resonant cavity, the other end of the primary resonant inductor of the resonant cavity is connected to one end of the primary resonant capacitor of the resonant cavity, the other end of the primary resonant capacitor of the resonant cavity is connected to one end of the primary coil of the transformer, and the other end of the primary coil of the transformer is connected to the midpoint of the second bridge arm.

[0019] In the above solution, the second circuit includes: a third bridge arm and a fourth bridge arm;

[0020] The third bridge arm includes a fifth switching tube and a sixth switching tube; the source of the fifth switching tube is connected to the positive pole of the second DC input port, the drain of the fifth switching tube is connected to the source of the sixth switching tube, and the drain of the sixth switching tube is connected to the negative pole of the second DC input port;

[0021] The fourth bridge arm includes a seventh switching tube and an eighth switching tube; the source of the seventh switching tube is connected to the positive pole of the second DC input port, the drain of the seventh switching tube is connected to the source of the eighth switching tube, and the drain of the eighth switching tube is connected to the negative pole of the second DC input port.

[0022] In the above solution, the resonant cavity circuit further includes: a resonant cavity secondary resonant inductor and a resonant cavity secondary resonant capacitor; wherein,

[0023] The midpoint of the third bridge arm is connected to one end of the secondary coil of the transformer;

[0024] The midpoint of the fourth bridge arm is connected to one end of the resonant cavity secondary resonant inductor, the other end of the resonant cavity secondary resonant inductor is connected to one end of the resonant cavity secondary resonant capacitor, and the other end of the resonant cavity secondary resonant capacitor is connected to the other end of the secondary coil of the transformer.

[0025] In the above solution, the three-phase BUCK - BOOST circuit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, a first inductor, a second inductor, and a third inductor;

[0026] The midpoint of the fifth bridge arm is connected to one end of the first inductor;

[0027] The midpoint of the sixth bridge arm is connected to one end of the second inductor;

[0028] The midpoint of the seventh bridge arm is connected to one end of the third inductor;

[0029] After the other end of the first inductor is connected to the other end of the second inductor and the other end of the third inductor, it is connected to a fourth filter capacitor.

[0030] In the above solution, the fifth bridge arm includes: a ninth switching tube and a tenth switching tube;

[0031] The source of the ninth switching tube is connected to the positive pole of the second DC input port, the drain of the ninth switching tube is connected to the source of the tenth switching tube, and the drain of the tenth switching tube is connected to the negative pole of the second DC input port.

[0032] In the above solution, the sixth bridge arm includes: an eleventh switching tube and a twelfth switching tube;

[0033] The source of the eleventh switching tube is connected to the positive pole of the second DC input port, the drain of the eleventh switching tube is connected to the source of the twelfth switching tube, and the drain of the twelfth switching tube is connected to the negative pole of the second DC input port.

[0034] In the above solution, the seventh bridge arm includes: a thirteenth switching tube and a fourteenth switching tube;

[0035] The source of the thirteenth switching tube is connected to the positive pole of the second DC input port, the drain of the thirteenth switching tube is connected to the source of the fourteenth switching tube, and the drain of the fourteenth switching tube is connected to the negative pole of the second DC input port.

[0036] The present utility model provides a battery charge and discharge system based on a bidirectional converter. The system includes: a bidirectional resonant converter and a three-phase BUCK-BOOST converter. Among them, the bidirectional resonant converter includes: a first DC input port, a first circuit, a resonant cavity circuit, and a second circuit. One end of the first DC input port is connected to one end of the first circuit, the other end of the first circuit is connected to one end of the resonant cavity circuit, and the other end of the resonant cavity circuit is connected to one end of the second circuit. The bidirectional BUCK-BOOST converter includes: a second DC input port and a three-phase BUCK-BOOST circuit. The second DC input port is connected to the other end of the synchronous rectifier bridge. The second DC input port is also connected to the three-phase BUCK-BOOST circuit, and the three-phase BUCK-BOOST circuit is connected to the DC output port. Thus, since both the resonant converter and the three-phase BUCK-BOOST converter have the function of bidirectional power flow, the energy storage system of the present utility model can both charge and discharge, so that there is no need to additionally arrange a set of discharge equipment, thereby reducing the space occupied by the equipment and also reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present utility model. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0038] Figure 1 The structural schematic diagram of a battery charge and discharge system based on a bidirectional converter according to an embodiment of the present utility model is shown.

[0039] DESCRIPTION OF THE REFERENCE NUMERALS

[0040] U1 - First DC input port; T1 - First circuit; T2 - Resonant cavity circuit; T3 - Second circuit; U2 - Second DC input port; T4 - Three-phase BUCK-BOOST circuit; C f1 - First filter capacitor; C f2 - Second filter capacitor; C f3 - Third filter capacitor; C f4 - Fourth filter capacitor; D1 - First switching tube; D2 - Second switching tube; D3 - Third switching tube; D4 - Fourth switching tube; D5 - Fifth switching tube; D6 - Sixth switching tube; D7 - Seventh switching tube; D8 - Eighth switching tube; L P - Primary resonant inductor of the resonant cavity; C P - Primary resonant capacitor of the resonant cavity; L S- Resonant cavity secondary resonant inductor; C S - Resonant cavity secondary resonant capacitor; D5 - The fifth switching tube; D6 - The sixth switching tube; D7 - The seventh switching tube; D8 - The eighth switching tube; L f1 - The first inductor; L f2 - The second inductor; L f3 - The third inductor; Q1 - The ninth switching tube; Q2 - The tenth switching tube; Q3 - The eleventh switching tube; Q4 - The twelfth switching tube; Q5 - The thirteenth switching tube; Q6 - The fourteenth switching tube. Detailed implementation manners

[0041] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0042] The present utility model provides a battery charging and discharging system based on a bidirectional converter, as Figure 1 shown. The system includes: a bidirectional resonant converter and a three-phase BUCK - BOOST converter; the bidirectional resonant converter can be a (CLLC, Capacitor - Inductor - Inductor - Capacitor) resonant converter; wherein,

[0043] The bidirectional resonant converter includes: a first DC input port U1, a first circuit T1, a resonant cavity circuit T2 and a second circuit T3; the first DC input port U1 is connected to one end of the first circuit T1, the other end of the first circuit T1 is connected to one end of the resonant cavity circuit T2, and the other end of the resonant cavity circuit T2 is connected to one end of the second circuit T3;

[0044] The three-phase BUCK - BOOST converter includes: a second DC input port U2, a three-phase BUCK - BOOST circuit T4; the second DC input port U2 is connected to the other end of the synchronous rectifier bridge T3; the second DC input port U2 is also connected to the three-phase BUCK - BOOST circuit T4, and the three-phase BUCK - BOOST circuit T4 is connected to the DC output port U3.

[0045] It should be noted that, since both the bidirectional resonant converter and the three-phase BUCK - BOOST converter in the present utility model can achieve bidirectional power flow, when the system is in the charging mode, the first circuit T1 acts as an inverter bridge circuit and the second circuit T3 acts as a synchronous rectifier bridge circuit; when the system is in the discharging mode, the first circuit T1 acts as the synchronous rectifier bridge circuit and the second circuit T3 acts as an inverter bridge circuit.

[0046] Here, referring to Figure 1 , the system further includes: a first filter capacitor C f1 , a second filter capacitor C f2 , a third filter capacitor C f3 and a fourth filter capacitor C f4 ;

[0047] The first filter capacitor C f1 is connected to the first DC input port U1; the first filter capacitor is the port filter capacitor of the first DC input port U1; the positive electrode of the first filter capacitor C f1 is connected to the positive electrode of U1, and the negative electrode of the first filter capacitor C f1 is connected to the negative electrode of U1;

[0048] The second filter capacitor C f2 is connected to the output terminal of the second circuit T3;

[0049] The third filter capacitor C f3 is connected to the second DC input port U2; the second filter capacitor is the port filter capacitor of the second DC input port U2;

[0050] The fourth filter capacitor C f4 is connected to the DC output port U3.

[0051] The functions of the first filter capacitor C f1 , the second filter capacitor C f2 , the third filter capacitor C f3 and the fourth filter capacitor C f4 are all for voltage stabilization.

[0052] Referring to Figure 1 , the first circuit T1 includes: a first bridge arm and a second bridge arm;

[0053] The first bridge arm includes a first switching tube D1 and a second switching tube D2; the source electrode of the first switching tube D1 is connected to the positive electrode of the first DC input port U1, the drain electrode of the first switching tube D1 is connected to the source electrode of the second switching tube D2, and the drain electrode of the second switching tube D2 is connected to the negative electrode of the first DC input port;

[0054] The second bridge arm includes a third switching tube D3 and a fourth switching tube D4; the source electrode of the third switching tube D3 is connected to the positive electrode of the first DC input port U1, the drain electrode of the third switching tube D3 is connected to the source electrode of the fourth switching tube D4, and the drain electrode of the fourth switching tube D4 is connected to the negative electrode of the first DC input port U1.

[0055] The resonant cavity circuit T2 includes: a transformer, a resonant cavity primary resonant inductor L P and a resonant cavity primary resonant capacitor C P, the secondary resonant inductor L of the resonant cavity S and the secondary resonant capacitor C of the resonant cavity S .

[0056] The second circuit T3 includes: a third bridge arm and a fourth bridge arm;

[0057] The third bridge arm includes a fifth switching tube D5 and a sixth switching tube D6; the source of the fifth switching tube D5 is connected to the positive pole of the second DC input port U2, the drain of the fifth switching tube D5 is connected to the source of the sixth switching tube D6, and the drain of the sixth switching tube D6 is connected to the negative pole of the second DC input port U2;

[0058] The fourth bridge arm includes a seventh switching tube D7 and an eighth switching tube D8; the source of the seventh switching tube D7 is connected to the positive pole of the second DC input port U2, the drain of the seventh switching tube D7 is connected to the source of the eighth switching tube D8, and the drain of the eighth switching tube D8 is connected to the negative pole of the second DC input port U2.

[0059] The midpoint of the first bridge arm is connected to one end of the primary resonant inductor L of the resonant cavity P of the resonant cavity, and the other end of the primary resonant inductor L of the resonant cavity P is connected to one end of the primary resonant capacitor C of the resonant cavity P of the resonant cavity, and the other end of the primary resonant capacitor C of the resonant cavity P is connected to one end of the primary coil of the transformer, and the other end of the primary coil of the transformer is connected to the midpoint of the second bridge arm.

[0060] The midpoint of the third bridge arm is connected to one end of the secondary coil of the transformer; the midpoint of the fourth bridge arm is connected to one end of the secondary resonant inductor L of the resonant cavity S of the resonant cavity, and the other end of the secondary resonant inductor L of the resonant cavity S is connected to one end of the secondary resonant capacitor C of the resonant cavity S of the resonant cavity, and the other end of the secondary resonant capacitor C of the resonant cavity S is connected to the other end of the secondary coil of the transformer.

[0061] It can be seen from Figure 1 that the positive pole of the second filter capacitor C f2 is connected to the source of D7, and the negative pole of the second filter capacitor C f2 is connected to the drain of D8.

[0062] Continue to refer to Figure 1 , the three-phase BUCK-BOOST circuit includes T4: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, a first inductor L f1 , a second inductor L f2 and a third inductor L f3 ;

[0063] The midpoint of the fifth bridge arm is connected to the first inductor L f1is connected to one end of;

[0064] The midpoint of the sixth bridge arm is connected to the second inductor L f2 at one end;

[0065] The midpoint of the seventh bridge arm is connected to the third inductor L f3 at one end;

[0066] The other end of the first inductor L f1 is connected to the other end of the second inductor L f2 and the other end of the third inductor L f3 After being connected, it is connected to the fourth filter capacitor C f4 .

[0067] The fifth bridge arm includes: the ninth switch tube Q1 and the tenth switch tube Q2;

[0068] The source of the ninth switch tube Q1 is connected to the positive pole of the second DC input port, the drain of the ninth switch tube Q1 is connected to the source of the tenth switch tube Q2, and the drain of the tenth switch tube Q2 is connected to the negative pole of the second DC input port U2.

[0069] The sixth bridge arm includes: the eleventh switch tube Q3 and the twelfth switch tube Q4;

[0070] The source of the eleventh switch tube Q3 is connected to the positive pole of the second DC input port U2, the drain of the eleventh switch tube Q3 is connected to the source of the twelfth switch tube Q4, and the drain of the twelfth switch tube Q4 is connected to the negative pole of the second DC input port U2.

[0071] The seventh bridge arm includes: the thirteenth switch tube Q5 and the fourteenth switch tube Q6;

[0072] The source of the thirteenth switch tube Q5 is connected to the positive pole of the second DC input port U2, the drain of the thirteenth switch tube Q5 is connected to the source of the fourteenth switch tube Q6, and the drain of the fourteenth switch tube Q6 is connected to the negative pole of the second DC input port.

[0073] In addition, in order to better achieve the filtering and voltage stabilization effect and reduce voltage fluctuation, a first capacitor C1 is also provided between the positive pole of the first DC input port U1 and the positive pole of the first filter capacitor, and a second capacitor C2 and a third capacitor C3 are also provided between the positive poles of the second filter capacitor and the third filter capacitor; a fourth capacitor C4 is also provided between the third inductor and the positive pole of the DC output port.

[0074] The battery charge and discharge system provided by the present utility model can not only realize the charging function but also realize the discharging function.

[0075] When the system is working in the forward direction, it is in the battery charging mode. The DC bus input end is filtered → the primary side of the resonant converter inverts the input DC bus into AC → the resonant cavity resonates → the secondary side of the resonant converter rectifies the AC output from the resonant cavity into DC to achieve electrical isolation → the DC power output from the resonant converter after electrical isolation is introduced into the input end of the BUCK-BOOST converter → input filtering → DC voltage is input into three sets of bridge arms in parallel. The three sets of bridge arms are respectively connected to the inductor, and a BUCK loop is formed according to the order in which the switch tubes are turned on. Finally, a DC voltage with a wide voltage range and small current ripple on the low-voltage side is output to charge the battery.

[0076] Specifically, in the charging mode, the DC input port is the first DC input port U1, and the DC output port is U3; the first switch tube D1 and the second switch tube D2 are turned on alternately; the third switch tube D3 and the fourth switch tube D4 are turned on alternately; the first switch tube D1 and the fourth switch tube D4 are turned on at the same time; the second switch tube D2 and the third switch tube D3 are turned on at the same time, and the switching frequency of each switch tube is kept synchronized, and the four switch tubes constitute the first circuit, which converts the input DC power into AC power and provides it to the resonant cavity for resonance processing. The resonant AC power is then rectified and output DC power through a synchronous rectifier bridge (composed of four switch tubes D5, D6, D7, and D8, the sixth switch tube D6 and the seventh switch tube D7 are turned on at the same time; the fifth switch tube D5 and the eighth switch tube D8 are turned on at the same time; and D6 and D5 are turned on alternately, and D7 and D8 are turned on alternately).

[0077] The DC power output by the resonant converter is input to the BUCK-BOOST converter through the U2 port (the circuit works in the BUCK step-down mode at this time). The third filter capacitor C f3 To perform filtering, the switch tubes Q1 and Q2 are turned on alternately (alternately according to a preset alternating conduction period), the switch tubes Q3 and Q4 are turned on alternately (alternately according to a preset alternating conduction period), and the switch tubes Q5 and Q6 are turned on alternately (alternately according to a preset alternating conduction period); the switch tubes Q1, Q3, and Q5 are turned on alternately with a phase difference of 120°, and the switch tubes Q2, Q4, and Q6 are turned on alternately with a phase difference of 120°.

[0078] The BUCK-BOOST converter has a wide output voltage range, small current ripple on the low-voltage side, and can step down the input DC power to a DC power suitable for battery charging. The DC output port U3 is connected to the battery input terminal to charge the battery. When charging the battery, the BUCK-BOOST converter first turns on the switch tubes Q1, Q3, and Q5, and turns off the switch tubes Q2, Q4, and Q6. The third filter capacitor C f3 The first inductor L f1 , the second inductor L f2 and the third inductor L f3Energy is stored, and then the switch tubes Q1, Q3, and Q5 are turned off, and the switch tubes Q2, Q4, and Q6 are turned on to form a loop. By utilizing the characteristic that the current in the inductor cannot change suddenly, the entire loop can charge the battery.

[0079] When the system works in reverse, it is in battery discharge mode, and the battery side input filtering is used → the DC voltage is input to the three bridge arms of the BUCK-BOOST converter (the fifth bridge arm, the sixth bridge arm and the seventh bridge arm). The three bridge arms are respectively connected to the inductor, and a BOOST loop is formed according to the sequence of the switch tubes being turned on, raising the output voltage and inputting it to the resonant converter → the primary side of the resonant converter (the secondary side corresponding to the charging mode) inverts the input DC power into AC power → the resonant cavity resonates → the secondary side of the resonant converter (the primary side corresponding to the charging mode) rectifies the AC power output from the resonant cavity into DC power to achieve electrical isolation → flows back to the DC bus end (U1 port).

[0080] Specifically, in the discharge mode, the DC input port is U3, and the DC output port is U1; the battery voltage flows into the three-phase BUCK-BOOST converter through the U3 port (the three-phase BUCK-BOOST circuit works in the BOOST boost mode at this time), and the fourth filter capacitor C f4 To perform input filtering, the switch tubes Q1 and Q2 are turned on alternately, the switch tubes Q3 and Q4 are turned on alternately, and the switch tubes Q5 and Q6 are turned on alternately; the switch tubes Q1, Q3, and Q5 are turned on alternately with a phase difference of 120°, and the switch tubes Q2, Q4, and Q6 are turned on alternately with a phase difference of 120°. The third filter capacitor C f3 Perform output filtering.

[0081] The DC power output by the BUCK-BOOST converter is input to the resonant converter through the U2 port. At this time, the synchronous rectifier bridge composed of the fifth switch tube D5, the sixth switch tube D6, the seventh switch tube D7 and the eighth switch tube D8 is transformed into an inverter bridge. The inverter bridge composed of the first switch tube D1, the second switch tube D2, the third switch tube D3 and the fourth switch tube D4 is transformed into a synchronous rectifier bridge. The first filter capacitor C f1 It is converted into the output filter capacitor, and finally the voltage inside the battery returns to the DC bus, completing the battery discharge process.

[0082] In the BUCK-BOOST converter, the switches Q2, Q4, and Q6 are turned on first, and the switches Q1, Q3, and Q5 are turned off. At this time, the first inductor L f1 , the second inductor L f2 and the third inductor L f3 Then, the switch tubes Q2, Q4 and Q6 are turned off, and the switch tubes Q1, Q3 and Q5 are turned on. By taking advantage of the characteristic that the current in the inductor cannot change suddenly, the inductor releases energy to form a loop, giving the third filter capacitor C f3Charging is carried out to raise the voltage output by the BUCK - BOOST converter to the resonant converter. The voltage passes through the resonant converter part and then returns to the DC bus, finally completing the battery discharge process.

[0083] It can be seen that the resonant converter can not only achieve bidirectional power transmission but also realize electrical isolation between the bus side and the battery side. The BUCK - BOOST converter can achieve bidirectional energy flow and has a wide voltage range, being applicable to the charging and discharging of various different types of batteries. Moreover, the BUCK - BOOST converter has small current ripple on the low - voltage side and a compact structure, reducing the space occupation.

[0084] In addition, the system can also include a control chip (such as a DSP control chip). The control chip can detect the current of each phase inductor and compare it with a preset current threshold. If it exceeds the threshold, the corresponding switching tube will be cut off to achieve over - current protection.

[0085] Similarly, the PLC controller can also detect the voltages on the bus side and the battery side and compare them with preset voltage thresholds. If they exceed the thresholds, the input or output will be cut off to achieve over - voltage protection and under - voltage protection.

[0086] Through one or more embodiments of the present utility model, the present utility model has the following beneficial effects or advantages:

[0087] The present utility model provides a battery charging and discharging system based on a bidirectional converter. The system includes: a bidirectional resonant converter and a three - phase BUCK - BOOST converter; wherein, the bidirectional resonant converter includes: a first DC input port, a first circuit, a resonant cavity circuit, and a second circuit; the first DC input port is connected to one end of the first circuit, the other end of the first circuit is connected to one end of the resonant cavity circuit, and the other end of the resonant cavity circuit is connected to one end of the second circuit; the bidirectional BUCK - BOOST converter includes: a second DC input port, a three - phase BUCK - BOOST circuit; the second DC input port is connected to the other end of the synchronous rectifier bridge; the second DC input port is also connected to the three - phase BUCK - BOOST circuit, and the three - phase BUCK - BOOST circuit is connected to the DC output port; thus, since both the resonant converter and the three - phase BUCK - BOOST converter have the function of bidirectional energy flow, the energy storage system of the present utility model can not only achieve charging but also discharging. In this way, there is no need to additionally arrange a set of discharging equipment, thereby reducing the space occupation of the equipment and also reducing the cost.

[0088] The above are only the preferred embodiments of the present utility model, and are not intended to limit the protection scope of the present utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A battery charging and discharging system based on a bidirectional converter, characterized in that: The system includes: a bidirectional resonant converter and a three-phase BUCK-BOOST converter; wherein, The bidirectional resonant converter comprises: a first DC input port, a first circuit, a resonant cavity circuit and a second circuit; the first DC input port is connected to one end of the first circuit, the other end of the first circuit is connected to one end of the resonant cavity circuit, and the other end of the resonant cavity circuit is connected to one end of the second circuit; The three-phase BUCK-BOOST converter includes: a second DC input port and a three-phase BUCK-BOOST circuit; the second DC input port is connected to the other end of the synchronous rectifier bridge; the second DC input port is also connected to the three-phase BUCK-BOOST circuit, and the three-phase BUCK-BOOST circuit is connected to the DC output port; wherein, When the system is in charging mode, the first circuit acts as an inverter bridge circuit, and the second circuit acts as a synchronous rectifier bridge circuit; when the system is in discharging mode, the first circuit acts as the synchronous rectifier bridge circuit, and the second circuit acts as the inverter bridge circuit.

2. The system according to claim 1, characterized in that The system further comprises: a first filter capacitor, a second filter capacitor, a third filter capacitor and a fourth filter capacitor; The first filter capacitor is connected to the first DC input port; The second filter capacitor is connected to the output end of the second circuit; The third filter capacitor is connected to the second DC input port; The fourth filter capacitor is connected to the DC output port.

3. The system according to claim 1, characterized in that The first circuit comprises: a first bridge arm and a second bridge arm; The first bridge arm includes a first switch tube and a second switch tube; the source of the first switch tube is connected to the positive electrode of the first DC input port, the drain of the first switch tube is connected to the source of the second switch tube, and the drain of the second switch tube is connected to the negative electrode of the first DC input port; The second bridge arm includes a third switch tube and a fourth switch tube; the source of the third switch tube is connected to the positive electrode of the first DC input port, the drain of the third switch tube is connected to the source of the fourth switch tube, and the drain of the fourth switch tube is connected to the negative electrode of the first DC input port.

4. The system according to claim 3, characterized in that The resonant cavity circuit includes: a transformer, a resonant cavity primary resonant inductor and a resonant cavity primary resonant capacitor; wherein, The midpoint of the first bridge arm is connected to one end of the primary resonant inductor of the resonant cavity, the other end of the primary resonant inductor of the resonant cavity is connected to one end of the primary resonant capacitor of the resonant cavity, the other end of the primary resonant capacitor of the resonant cavity is connected to one end of the primary coil of the transformer, and the other end of the primary coil of the transformer is connected to the midpoint of the second bridge arm.

5. The system according to claim 1, wherein: The second circuit comprises: a third bridge arm and a fourth bridge arm; The third bridge arm includes a fifth switch tube and a sixth switch tube; the source of the fifth switch tube is connected to the positive electrode of the second DC input port, the drain of the fifth switch tube is connected to the source of the sixth switch tube, and the drain of the sixth switch tube is connected to the negative electrode of the second DC input port; The fourth bridge arm includes a seventh switch tube and an eighth switch tube; the source of the seventh switch tube is connected to the positive electrode of the second DC input port, the drain of the seventh switch tube is connected to the source of the eighth switch tube, and the drain of the eighth switch tube is connected to the negative electrode of the second DC input port.

6. The system according to claim 5, characterized in that The resonant cavity circuit also includes: a resonant inductor on the secondary side of the resonant cavity and a resonant capacitor on the secondary side of the resonant cavity; wherein, The midpoint of the third bridge arm is connected to one end of the transformer secondary coil; The midpoint of the fourth bridge arm is connected to one end of the resonant inductor of the secondary side of the resonant cavity, the other end of the resonant inductor of the secondary side of the resonant cavity is connected to one end of the resonant capacitor of the secondary side of the resonant cavity, and the other end of the resonant capacitor of the secondary side of the resonant cavity is connected to the other end of the secondary coil of the transformer.

7. The system according to claim 1, characterized in that The three-phase BUCK-BOOST circuit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, a first inductor, a second inductor and a third inductor; The midpoint of the fifth bridge arm is connected to one end of the first inductor; The midpoint of the sixth bridge arm is connected to one end of the second inductor; The midpoint of the seventh bridge arm is connected to one end of the third inductor; The other end of the first inductor is connected to the other end of the second inductor and the other end of the third inductor, and then connected to a fourth filter capacitor.

8. The system according to claim 7, characterized in that The fifth bridge arm includes: a ninth switch tube and a tenth switch tube; The source of the ninth switch tube is connected to the positive electrode of the second DC input port, the drain of the ninth switch tube is connected to the source of the tenth switch tube, and the drain of the tenth switch tube is connected to the negative electrode of the second DC input port.

9. The system according to claim 7, characterized in that The sixth bridge arm includes: an eleventh switch tube and a twelfth switch tube; The source of the eleventh switch tube is connected to the positive electrode of the second DC input port, the drain of the eleventh switch tube is connected to the source of the twelfth switch tube, and the drain of the twelfth switch tube is connected to the negative electrode of the second DC input port.

10. The system according to claim 7, characterized in that The seventh bridge arm includes: a thirteenth switch tube and a fourteenth switch tube; The source of the thirteenth switch tube is connected to the positive electrode of the second DC input port, the drain of the thirteenth switch tube is connected to the source of the fourteenth switch tube, and the drain of the fourteenth switch tube is connected to the negative electrode of the second DC input port.

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