CN115498721A - Charge-discharge integrated system - Google Patents

Abstract

A charging and discharging integrated system comprises a first bidirectional conversion circuit, a high-frequency transformer, a second bidirectional conversion circuit, an inversion discharging output path and an alternating current charging input path; the working frequency of the high-frequency transformer exceeds 15kHz; the second bidirectional conversion circuit is an H-bridge conversion circuit; when discharging, the first bidirectional conversion circuit converts the direct-current power supply output by the energy storage system into a pulse power supply, and a parasitic diode of a first power tube of the second bidirectional conversion circuit rectifies the pulse power supply output by the high-frequency transformer; during charging, the second bidirectional conversion circuit converts a direct-current power supply signal output after rectification of the alternating-current charging input channel into a pulse power supply, and the first bidirectional conversion circuit is used for rectifying the pulse power supply output by the high-frequency transformer into the direct-current power supply. The first bidirectional conversion circuit, the high-frequency transformer and the second bidirectional conversion circuit are shared for charging and discharging, the system size is reduced, the problems of high safety risk and EMC interference are solved, and the total cost is reduced.

Description

Charge-discharge integrated system

Technical Field

The invention relates to the technical field of charging and discharging, in particular to a charging and discharging integrated system.

Background

DC/DC switching power supplies are commonly used for voltage conversion and may be used in charging and discharging circuits for energy storage systems (e.g., batteries) and the like. However, in the prior art, most DC/DC switching power supplies are operated in one direction, i.e., either during charging or discharging. If the charging and discharging are required, two DC/DC switching power supplies are required, so that the cost and the size of the energy storage system charging and discharging integrated system are high.

In addition, although the individual energy storage system charge-discharge integrated system realizes charge-discharge integration, the two DC/DC switching power supplies are simply designed together in structure, or the two DC/DC switching power supplies are realized through a double half bridge, an H bridge, a buck-boost topology or other alternative topologies. The former has not solved the fundamental problem with high costs, bulky, and the latter has the system reliability relatively poor, the ann rule risk is big, EMC disturbs serious scheduling problem.

Disclosure of Invention

The invention aims to at least solve the technical problems in the prior art and provides a charging and discharging integrated system which is low in cost, small in size, reliable, safe and stable.

In order to achieve the above object, the present invention provides a charging and discharging integrated system for an energy storage system, wherein the energy storage system is a battery or a battery pack; the charging and discharging integrated system comprises a first bidirectional conversion circuit, a high-frequency transformer, a second bidirectional conversion circuit, an inversion discharging output passage and an alternating current charging input passage, wherein the first bidirectional conversion circuit, the high-frequency transformer and the second bidirectional conversion circuit are sequentially connected with one another; the high-frequency transformer is a power transformer with the working frequency exceeding 10 kHz; the second bidirectional conversion circuit is an H-bridge conversion circuit consisting of four first power tubes; when the energy storage system discharges, the first bidirectional conversion circuit converts a direct-current power supply signal output by the energy storage system into a pulse power supply signal, and the second bidirectional conversion circuit rectifies the pulse power supply signal output by the high-frequency transformer by using the parasitic diodes of the four first power tubes; when the energy storage system is charged, the second bidirectional conversion circuit converts the direct-current power supply signal output after the alternating-current charging input channel is rectified into a pulse power supply signal, and the first bidirectional conversion circuit rectifies the pulse power supply signal output by the high-frequency transformer into the direct-current power supply signal.

The technical scheme is as follows: when the energy storage system discharges outwards, direct current output by the energy storage system is converted into a pulse power supply signal through the first bidirectional conversion circuit and is input into a primary winding of the high-frequency transformer, alternating current signals output by a secondary winding of the high-frequency transformer after the high-frequency transformer is boosted are directly rectified through a parasitic diode of a first power tube of the second bidirectional conversion circuit, and the rectified direct current signals are input into the inversion discharge output circuit and are inverted into alternating current signals and then are output; when the energy storage system is charged, an external alternating current signal is rectified into a direct current power supply signal by the alternating current charging input passage, the direct current power supply signal is converted into an alternating current signal through the second bidirectional conversion circuit and is input to the secondary winding of the high-frequency transformer, and after the high-frequency transformer reduces the voltage, a pulse power supply signal output by the primary winding of the high-frequency transformer is converted into a direct current power supply signal through the first bidirectional conversion circuit to charge the energy storage system.

The system realizes that the energy storage system shares the first bidirectional conversion circuit, the high-frequency transformer and the second bidirectional conversion circuit during charging and discharging, the first bidirectional conversion circuit, the high-frequency transformer and the second bidirectional conversion circuit all work in two directions, particularly, in the discharging process, a pulse power supply signal output by the high-frequency transformer is rectified by directly utilizing a parasitic diode of a first power tube of the second bidirectional conversion circuit, a rectifying circuit is not needed to be additionally arranged, the system volume is greatly reduced, the problems of high safety risk and serious EMC interference are solved, and the total cost of the system can be reduced.

Drawings

Fig. 1 is a system block diagram of a charging and discharging integrated system in embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a charging and discharging integrated system in embodiment 1 of the present invention;

fig. 3 is another specific structural schematic diagram of the charge and discharge integrated system in embodiment 1 of the present invention;

fig. 4 is a schematic structural view of a charge and discharge integration system in embodiment 2 of the present invention;

fig. 5 is a schematic structural view of a charge and discharge integration system in embodiment 3 of the present invention;

fig. 6 is a diagram showing the structure of an LC quasi-resonant circuit in embodiments 1 to 3 of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.

Example 1

The embodiment discloses a charging and discharging integrated system, as shown in fig. 1, which is used for an energy storage system, wherein the energy storage system is a battery or a battery pack; the system comprises a first bidirectional conversion circuit, a high-frequency transformer, a second bidirectional conversion circuit, an inversion discharge output path and an alternating current charging input path, wherein the first bidirectional conversion circuit, the high-frequency transformer and the second bidirectional conversion circuit are sequentially connected with one another; the charging and discharging end of the energy storage system is connected with the first end of the first bidirectional conversion circuit, the second end of the first bidirectional conversion circuit is connected with the primary winding of the high-frequency transformer, the secondary winding of the high-frequency transformer is connected with the first end of the second bidirectional conversion circuit, and the second end of the second bidirectional conversion circuit is respectively connected with the inversion discharging output path and the alternating current charging input path. The second bidirectional conversion circuit is an H-bridge conversion circuit composed of four first power transistors, specifically shown as Q1 to Q4 in fig. 2 to 5.

When the energy storage system discharges, the first bidirectional conversion circuit converts a direct-current power supply signal output by the energy storage system into a pulse power supply signal, and the second bidirectional conversion circuit rectifies the pulse power supply signal output by the secondary winding side of the high-frequency transformer by using a parasitic diode of the first power tube; when the energy storage system is charged, the second bidirectional conversion circuit converts the direct-current power supply signal output after the alternating-current charging input channel is rectified into a pulse power supply signal, and the first bidirectional conversion circuit rectifies the pulse power supply signal output by the primary winding of the high-frequency transformer into the direct-current power supply signal.

In this embodiment, the high-frequency transformer is a power transformer with a working frequency exceeding 15kHz, and is mainly used as a high-frequency switching power transformer in a high-frequency switching power supply, and is also used as a high-frequency inverter power transformer in a high-frequency inverter power supply and a high-frequency inverter welding machine. According to the working frequency, the method can be divided into several grades: 15kHz to 50kHz, 50kHz to 100kHz, 100kHz to 500kHz, 500kHz to 1MHz, and above 10 MHz.

In this embodiment, the first bidirectional conversion circuit is to perform both rectification and DC-AC conversion, and specifically, the first bidirectional conversion circuit may include two parallel branches, one is a rectification branch for charging the energy storage system, and the other is a DC-AC conversion branch for discharging the energy storage system, and the two branches are switched by a switch, the rectification branch is preferably, but not limited to, an existing full-bridge or half-bridge diode rectification circuit, and the DC-AC conversion branch is preferably, but not limited to, an existing push-pull topology circuit or a full-bridge topology circuit based on a power transistor.

In this embodiment, in order to further reduce the cost, reduce the system size, and realize a device shared by the charging path and the discharging path as much as possible, as shown in fig. 2, the first bidirectional conversion circuit is a push-pull topology circuit composed of 2 positive integer multiples of the second power transistors, for example, 2 second power transistors, that is, Q5 and Q6, and when the circuit operates, only one of the two symmetrical second power transistors (Q5 and Q6) is turned on at a time, so that the conduction loss is small, and the efficiency is high.

As shown in fig. 2, the second power transistor is preferably but not limited to an NMOS power transistor or an IGBT or a SIC or GaN. The dotted terminal Np1 of the primary winding of the high-frequency transformer is connected with the drain electrode of the second power tube Q5, the source electrode of the second power tube Q5 is connected with the ground, the dotted terminal Np2 of the primary winding of the high-frequency transformer is connected with the charging and discharging end of the energy storage system, the common terminal of the primary winding of the high-frequency transformer is connected with the drain electrode of the second power tube Q5, and the source electrode of the second power tube Q5 is connected with the ground.

When the energy storage system discharges, the alternating on-off of the Q5 and the Q6 is realized by controlling the high-low level change of the grid voltage of the second power tube Q5 and the grid voltage of the second power tube Q6, so that a direct-current power supply signal output by the energy storage system is converted into a pulse power supply signal and is transmitted to the high-frequency transformer for boosting conversion. When the energy storage system is charged, the grid electrodes of the Q5 and the Q6 can be controlled to be suspended or the Q5 and the Q6 can be controlled to be disconnected, the pulse power supply signal output by the primary winding of the high-frequency transformer is rectified and converted into a direct-current power supply signal through parasitic diodes (also called parasitic diodes) of the Q5 and the Q6, so that an additional rectifying circuit is not needed, the cost is reduced, the circuit is simplified, and the circuit volume is reduced.

When the charging current is large, in order to reduce heat generation during the use of Q5 and Q6 rectification, it is further preferable that schottky diodes for rectification be connected between the source and drain of all the second power transistors in the first bidirectional conversion circuit, and the conduction direction of the schottky diodes is opposite to the conduction current direction when the second power transistors are conducted. By connecting the schottky diode in parallel with the parasitic diode of the second power tube, the line impedance can be reduced, and the heat loss can be reduced. As shown in fig. 2, a schottky diode may be connected between the drain and source of Q5 and/or Q6, respectively, with the cathode of schottky diode D1 connected to the drain of Q5, the anode of schottky diode D1 connected to the source of Q5, the cathode of schottky diode D2 connected to the drain of Q6, and the anode of schottky diode D2 connected to the source of Q6. Therefore, the bidirectional operation of the first bidirectional conversion circuit can be realized by adding two Schottky diodes, the cost is lower, and the bidirectional conversion circuit can operate under large current. When the charging current is small, the parasitic diodes of the Q5 and the Q6 are directly used for rectification, so that the requirement can be met.

In this embodiment, to further reduce the cost, reduce the system size, and realize the common devices of the charging path and the discharging path as many as possible, as shown in fig. 3, the first bidirectional conversion circuit may also be a full-bridge topology circuit composed of positive integer multiples of 4 power tubes, for example, when there are 4 power tubes, the four second power tubes are Q5, Q6, Q7, and Q8, respectively, and are connected in an H-bridge manner. The second power tube is preferably but not limited to an NMOS power tube or an IGBT or a SIC or a GaN. When the energy storage system is charged, a full-bridge rectification circuit constructed by parasitic diodes of Q5, Q6, Q7 and Q8 can be directly utilized for rectification, and when the energy storage system is discharged, the direct current-to-alternating current conversion is realized by controlling the alternate on-off of two pairs of diagonal NMOS power tubes in Q5, Q6, Q7 and Q8. When the charging current of the energy storage system is relatively large, in order to reduce the current heat loss, as shown in fig. 3, schottky diodes for rectification are connected between the source and the drain of all the second power transistors in the first bidirectional conversion circuit, the conduction direction of the schottky diodes is opposite to the conduction current direction when the second power transistors are conducted, as shown in fig. 3, schottky diodes D1, D2, D3, and D4 are respectively connected, and the specific operating principle and connection may refer to the above description and are not described again.

In this embodiment, the second bidirectional converter circuit is an H-bridge converter circuit composed of four first power transistors, as shown in fig. 2-5, the first power transistors are preferably but not limited to NMOS power transistors, IGBT, SIC, or GaN, the first power transistors Q1-Q4 constitute the H-bridge converter circuit, the drain of the first power transistor Q1 and the drain of the third power transistor Q3 are both connected to the inverter discharge output path and the ac charge input path, the source of the first power transistor Q1 is connected to the alternating end of the secondary winding of the high-frequency transformer and the drain of the second power transistor Q2, the source of the third power transistor Q3 is connected to the common end of the secondary winding of the high-frequency transformer and the drain of the fourth power transistor Q4, and the source of the second power transistor Q2 and the source of the fourth power transistor Q4 are connected to ground. When the energy storage system discharges, the grid electrodes of the Q1-Q4 are controlled to be opened or disconnected, the parasitic diodes of the Q1-Q4 form a full-bridge rectification circuit, and boosted pulse power signals output by the secondary winding of the high-frequency transformer are rectified to form high-voltage direct-current power signals which are transmitted to a rear-stage inversion discharge output path. The inventor of the application finds that the boosted pulse power supply signal current is relatively low, and the parasitic diode can be reliably and safely rectified by reasonably selecting the types of Q1-Q4. When the energy storage system is charged, the direct current power supply signals rectified by the alternating current charging input path are input into a full bridge circuit formed by Q1-Q4, and the direct current power supply signals are converted into pulse power supply signals by controlling the alternate on-off of two pairs of diagonal power tubes in the Q1-Q4.

In this embodiment, in order to reduce the influence of the interference signal on the subsequent circuit when the energy storage system is discharged or reduce the influence of the charging power supply on the energy storage system after the energy storage system is charged, it is further preferable that, as shown in fig. 2 to 5, the system further includes a first filter circuit connected in series to a connection path between the energy storage system and the first bidirectional conversion circuit, a first end of the first filter circuit is connected to a charging/discharging end of the energy storage system, and a second end of the first filter circuit is connected to a first end of the first bidirectional conversion circuit; the charging and discharging ends of the energy storage system, i.e. the power output/input ends of the energy storage system, are usually the same pin, and if the energy storage system is a Battery, the charging and discharging ends of the energy storage system are Battery ends of the Battery. The first filter circuit is preferably, but not limited to, an existing RC passive low-pass filter circuit or a parallel circuit of a plurality of ground bypass filter capacitors.

In this embodiment, in order to reduce the influence of noise interference (e.g., high frequency interference) in the dc power signal rectified by the second bidirectional conversion circuit on the operating performance of the inverter circuit in the inverter discharge output path when the energy storage system is discharging, and in order to reduce noise interference (e.g., high frequency interference) in the dc power signal rectified by the ac charging input path when the energy storage system is charging, it is further preferable that, as shown in fig. 2 to 5, a second filter circuit is further included, the second filter circuit is connected to a second end of the second bidirectional conversion circuit, a first end of the second filter circuit is connected to a second end of the second bidirectional conversion circuit, and a first end of the second filter circuit is connected to the inverter discharge output path and the ac charging input path, respectively. The second filter circuit is preferably, but not limited to, an existing RC passive low-pass filter circuit or a parallel circuit of a plurality of ground bypass filter capacitors.

In this embodiment, in order to realize different voltage boosting ratios of the high-frequency transformer when the energy storage system is discharged and different voltage reducing ratios of the high-frequency transformer when the energy storage system is charged, it is further preferable that at least 1 tap is provided on the secondary winding of the high-frequency transformer, and different taps correspond to different turn ratios, as shown in fig. 2 to 5. The high-frequency transformer further comprises a multi-channel switch, a secondary winding of the high-frequency transformer forms at least two secondary sub-windings through at least one tap, each secondary sub-winding is correspondingly connected with one LC quasi-resonant circuit, and the multi-channel switch switches the LC quasi-resonant circuits connected with different secondary sub-windings to be connected with the first end of the second bidirectional conversion circuit. The multi-channel switch is provided with a plurality of movable contacts, the movable contacts are correspondingly connected with the secondary sub-windings one by one, and the fixed contacts of the multi-channel switch are respectively connected with the first ends of the second bidirectional conversion circuits. The multi-channel switch is preferably, but not limited to, a multi-contact relay, preferably, but not limited to, a model number CHI03-S-112DC2.

In this embodiment, in order to reduce the switching loss of the power transistor in the system circuit topology and greatly improve EMC, it is further preferable that the high-frequency transformer and the second bidirectional conversion circuit are connected in series, an input terminal of the LC quasi-resonant circuit is connected to the secondary winding of the high-frequency transformer, and an output terminal of the LC quasi-resonant circuit is connected to the first terminal of the second bidirectional conversion circuit. The LC quasi-resonant circuit comprises a resonant inductor and a resonant capacitor connected in series, and as shown in fig. 6, the final resonant inductor comprises the inductance value of the resonant inductor and the leakage inductance of a coil part where a tap connected to the high-frequency transformer is located.

In the present embodiment, as shown in fig. 6, the secondary winding of the high-frequency transformer is provided with 1 tap, and has two secondary sub-windings, the connection points of the two secondary sub-windings are respectively pin 10 and pin 9, and the multi-channel switch is K1. When the moving contact of K1 is connected with pin 10, the leakage inductance of the capacitor C15, the capacitor C17 and the pin 10 to pin 7 form an LC quasi-resonant circuit. When the moving contact of K1 is connected with pin 9, the resonant inductor L1, the capacitor C18, the capacitor C25 and the leakage inductance from pin 9 to pin 7 form an LC quasi-resonant circuit, and pin 7 is the common end of the secondary winding.

In this embodiment, preferably, as shown in fig. 2, the inverter circuit, the first relay, the first EMC suppressing circuit, the second relay, and the ac output port are connected to the inverter discharge output path in this order; the alternating current charging input path is sequentially connected with a rectifying circuit, a first relay, a first EMC (electro magnetic compatibility) suppression circuit, a second relay and an alternating current input port; the first relay, the first EMC suppression circuit and the second relay are shared by the inversion discharging output path and the alternating current charging input path, the first relay controls the first end of the first EMC suppression circuit to be connected with the second end of the inversion circuit or the second end of the rectification circuit, and the second relay controls the second end of the first EMC suppression circuit to be connected with the alternating current output port or the alternating current input port. The first EMC suppression circuit is preferably, but not limited to, an existing magnetic bead or a magnetic bead common mode inductor. The first relay and the second relay are preferably, but not limited to, existing relay elements comprising one contact and two moving contacts. The rectifier circuit is preferably, but not limited to, an existing diode full-bridge or half-bridge rectifier circuit.

In this embodiment, it is further preferable that, in order to remove the dc background interference in the inverted ac signal, an LC filter circuit is further included, a first end of the LC filter circuit is connected to a second end of the inverter circuit, and a second end of the LC filter circuit is connected to a first end of the first EMC suppression circuit. The LC filter circuit is preferably, but not limited to, an existing inductive, capacitive series filter circuit.

In this embodiment, the AC voltage formed by the inverter circuit and the LC filter circuit passes through the first relay 1, the first EMC suppression circuit, the second relay, and finally the AC output port. And the AC output port and the AC input port are controlled to be connected to the main circuit through a second relay.

In an application scenario of this embodiment, the energy storage system is a battery system, a schematic circuit structure diagram of the system is shown in fig. 2, the battery system passes through a first filter circuit and then is connected to power tubes Q5 and Q6, and then forms a push-pull topology with a primary side (low-voltage side) of a high-frequency transformer HT1, two windings of a secondary side (high-voltage side) of the high-frequency transformer HT1 are connected to a quasi-resonance and control circuit thereof, and finally connected to a second filter circuit to form a boost circuit.

1. When the battery system is discharged, the method comprises the following steps:

(1) DC/DC boost process

The battery system is filtered by the first filter circuit, then is boosted by a push-pull switching power supply composed of Q5, Q6 and HT1, generates resonant current by the quasi-resonance and control circuit thereof, is rectified by parasitic diodes of power tubes Q1, Q2, Q3 and Q4, and then forms high-voltage direct-current bus voltage by the second filter circuit. 4 full-wave rectifier diodes needed in the boosting process are replaced by the parasitic diodes of the power tubes Q1, Q2, Q3 and Q4, the purpose of multiplexing the power tubes Q1, Q2, Q3 and Q4 is achieved, and the system cost is reduced.

In the boosting process, quasi-resonance and its control circuit play an important role, and as shown in fig. 6, the circuit comprises a resonance capacitor (in this case, leakage inductance of a secondary winding of a high-frequency transformer is used as resonance inductance) and a relay K1 which are connected in series in the circuit, or comprises an LC series resonance circuit and the relay K1.

When the voltage is boosted, the relay is automatically connected with a secondary winding (NS 1 or NS 2) of the high-frequency transformer HT1, so that the leakage inductance of the winding and a resonant capacitor (LC series resonant circuit) form a resonant circuit, and the DC/DC circuit forms sinusoidal current. Through proper calculation, the resonance period is slightly smaller than the switching period of the push-pull switching power supply, and the Zero Current Switch (ZCS) obtained in the discharging process is finally realized by utilizing the characteristic of twice zero crossing points of the sine wave half period, so that the switching loss of a power tube is reduced, and the EMC is greatly improved.

(2) DC/AC inverter output process

As shown in fig. 2, the second filter circuit is connected to the inverter circuit and the LC filter circuit, and the circuit is connected to the first EMC suppression circuit after passing through the first relay circuit 1, and is finally connected to the AC output port through the second relay. The high-voltage direct-current bus formed in the boosting process passes through an H-bridge inverter circuit formed by 4 power tubes Q1-Q4 and an LC filter circuit to form AC voltage meeting requirements. The first relay will automatically connect the first EMC suppression circuit and the second relay circuit will automatically connect the first EMC suppression circuit to the AC output port, thereby realizing the whole discharging process.

2. When the battery system is charged, the method comprises the following processes:

(1) Input EMC filtering and full wave rectification process

As shown in fig. 2, the AC input port is connected to the first EMC suppression circuit through the second relay, the first EMC suppression circuit is further connected to the first relay, the first relay is connected to the rectification circuit, and the rectification circuit is finally connected to the second filter circuit. After AC (commercial power) is connected into the system through the AC input port, the second relay is automatically connected to the first EMC suppression circuit, and the circuit can greatly suppress and reduce EMC generated in the charging process. At the moment, the first relay can automatically disconnect the inverter circuit and the LC filter circuit and automatically connect the rectifying circuit. AC (commercial power) is filtered by the second filter circuit after being subjected to full-wave rectification by the rectifying circuit, so that high-voltage direct current voltage is formed. The process shares a first EMC suppression circuit and a second filter circuit with the discharging process; the first relay can be automatically switched from being connected with the inverter circuit and the LC filter circuit to being connected with the rectifying circuit.

(2) Step-down charging process

As shown in fig. 2, the second filter circuit is connected to a second bidirectional conversion circuit, which is a full bridge circuit formed by power transistors Q1, Q2, Q3, and Q4, and the full bridge circuit is connected to a secondary winding (NS 1 or NS 2) of the high frequency transformer HT1 via the LC quasi-resonant circuit and its control circuit. The primary winding of HT1 is connected to power transistors Q5 and Q6 of the first bidirectional conversion circuit, and finally to the battery system via the first filter circuit.

The high-voltage direct-current bus filtered by the second filter circuit is subjected to voltage reduction through a full-bridge circuit formed by power tubes Q1, Q2, Q3 and Q4 of the second bidirectional conversion circuit, an LC quasi-resonance circuit, a control circuit of the LC quasi-resonance circuit and a full-bridge switching power supply topology formed by a high-frequency transformer HT 1. Pulse voltages output by low-voltage side windings NP1 and NP2 of the HT1 are rectified by power tubes Q5 and Q6 of a bidirectional conversion circuit and filtered by a first filter circuit to form low-voltage charging voltage for charging a battery system.

In particular, the LC quasi-resonant circuit and its control circuit play an important role in the voltage reduction process. When voltage is reduced, a relay (multi-channel switch) in the LC quasi-resonant circuit and the control circuit thereof can be automatically connected with a high-voltage side winding (NS 1 or NS 2) of the high-frequency transformer HT1, a resonant circuit is formed, the DC/DC circuit forms sinusoidal current, and finally Zero Current Switching (ZCS) in the charging process is realized, so that the switching loss of the whole topological power tube is reduced, and the EMC is greatly improved.

Particularly, when the system is charged, a relay (multi-channel switch) in the LC quasi-resonant circuit and the control circuit thereof is automatically connected with one winding on the high-voltage side of the high-frequency transformer HT1, so that the transformation ratio of the high-frequency transformer HT1 is changed, and the requirement of the voltage reduction ratio of the system is met.

In particular, to further improve the system efficiency, the power transistors Q5 and Q6 of the first bidirectional conversion circuit may be driven by using the principle of synchronous rectification, so as to reduce the loss of Q5 and Q6 to the maximum.

In particular, in order to further improve the system efficiency, schottky diodes, such as schottky diodes D1 and D2 shown in fig. 2, may be connected in parallel to the source and drain terminals of the power transistors Q5 and Q6 of the first bidirectional conversion circuit. Although the system efficiency is slightly lower than the full-wave rectification scheme, the driving circuits of Q5 and Q6 of the first bidirectional conversion circuit can be greatly simplified.

Example 2

The embodiment discloses a charging and discharging integrated system, which is different from the embodiment 1 in that an inverter discharging output path and an alternating current charging input path are different, and as shown in fig. 4, an inverter circuit, a first relay, a first EMC suppression circuit and an alternating current output port are sequentially connected to the inverter discharging output path; the alternating current charging input path is sequentially connected with a rectifying circuit, a first relay, a second EMC suppression circuit and an alternating current input port; the first relay is shared by the inversion discharging output path and the alternating current charging input path, and controls the first end of the first EMC suppression circuit to be connected with the second end of the inversion circuit or the second end of the rectification circuit.

In this embodiment, the second relay is eliminated, the AC input port is connected to the second EMC suppression circuit, and the AC output port is connected to the first EMC suppression circuit, and the main circuit is switched by the first relay. The AC output port and the AC input port are respectively connected with an EMC suppression circuit and then switched to the main circuit through a first relay.

Example 3

The embodiment discloses a charging and discharging integrated system, and the difference between the embodiment and the embodiment 1 is that an inverter discharging output path and an alternating current charging input path, and the embodiment cancels an AC rectifier bridge circuit and a first relay in a charging process.

As shown in fig. 5, the inverter discharge output path is sequentially connected with a bidirectional inverter circuit, a first EMC suppression circuit, a second relay and an ac output port; the alternating current charging input path is sequentially connected with a bidirectional inverter circuit, a first EMC suppression circuit, a second relay and an alternating current input port; the inverter discharge output path and the alternating current charging input path share a bidirectional inverter circuit, a first EMC suppression circuit and a second relay, and the second relay controls a second end of the first EMC suppression circuit to be connected with an alternating current output port or an alternating current input port; the bidirectional inverter circuit is an H-bridge conversion circuit composed of four third power transistors (not shown). The third power tube is preferably but not limited to an NMOS power tube or an IGBT or a SIC or a GaN.

In this embodiment, as shown in fig. 5, when AC (mains) is connected for charging, the second relay circuit will automatically connect the AC input port to the first EMC suppression circuit. After passing through the first EMC suppression circuit, the AC power is directly connected to the bidirectional inverter circuit and the LC filter circuit, and is rectified by the parasitic diodes of 4 power transistors of the inverter H-bridge, instead of the rectifier circuits in embodiments 1 and 2. The AC alternating current signal is rectified by a parasitic diode of an H bridge of the bidirectional inverter circuit and then passes through the second filter circuit to form high-voltage direct current bus voltage. In the charging process, the AC (commercial power) utilizes the parasitic diodes of 4 power tubes of the H bridge of the bidirectional inverter circuit to realize full-wave rectification, thereby not only simplifying the circuit of the system, but also reducing a large number of devices and further reducing the total cost of the system.

The charging and discharging integrated system provided by the invention adopts a unique LC quasi-resonant circuit, a control circuit and an AC input/output switching circuit to realize the purposes of organically integrating charging and discharging of an energy storage system and sharing a power device. Meanwhile, the following problems are solved:

1. the risks such as personal injury and the like caused by electric leakage are solved by utilizing push-pull and full-bridge electromagnetic isolation and AC input/output ports respectively and independently, and the high-voltage side and the low-voltage side of the energy storage system can meet the requirement of enhancing the insulation grade;

2. the high-voltage side winding of the high-frequency transformer HT1 is split into two windings, and the two windings can be connected in series at the first position or exist independently. The high-voltage side winding is connected with a resonant capacitor or an LC resonant circuit in series, and a relay (a multi-channel switch) is used for realizing the switching of the winding turn ratio, so that the transformation ratio requirement required by the DC/DC bidirectional operation is met.

3. The series resonance capacitor or LC resonance circuit enables loops at two sides of a high-frequency transformer HT1 of the DC/DC to form sinusoidal current, the requirement of reducing the switching loss of the system is met, and meanwhile EMC of the whole system can be greatly reduced.

4. In the charging and discharging process, the system multiplexes a high-frequency transformer HT1, power tubes on two sides of the high-frequency transformer, a filter circuit, a quasi-resonance circuit, a control circuit of the quasi-resonance circuit and an EMC suppression circuit. In particular, in embodiment 3, the power transistor of the H bridge of the inverter circuit is also multiplexed, and the rectifier bridge circuit required for AC input is reduced, which not only simplifies the system circuit, but also reduces a large number of devices, and further reduces the total cost of the system.

In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. A charging and discharging integrated system is characterized by being used for an energy storage system, wherein the energy storage system is a battery or a battery pack; the charging and discharging integrated system comprises a first bidirectional conversion circuit, a high-frequency transformer, a second bidirectional conversion circuit, an inversion discharging output path and an alternating current charging input path, wherein the first bidirectional conversion circuit, the high-frequency transformer and the second bidirectional conversion circuit are sequentially connected with one another, and the inversion discharging output path and the alternating current charging input path are respectively connected with the second end of the second bidirectional conversion circuit;

the high-frequency transformer is a power transformer with the working frequency exceeding 15kHz;

the second bidirectional conversion circuit is an H-bridge conversion circuit consisting of four first power tubes;

when the energy storage system discharges, the first bidirectional conversion circuit converts a direct-current power supply signal output by the energy storage system into a pulse power supply signal, and the second bidirectional conversion circuit rectifies the pulse power supply signal output by the high-frequency transformer by using the parasitic diodes of the four first power tubes;

when the energy storage system is charged, the second bidirectional conversion circuit converts the direct-current power supply signal output after the alternating-current charging input channel is rectified into a pulse power supply signal, and the first bidirectional conversion circuit rectifies the pulse power supply signal output by the high-frequency transformer into the direct-current power supply signal.

2. The integrated charge-discharge system according to claim 1, wherein the first bidirectional conversion circuit is a push-pull topology circuit composed of 2 positive integer multiples of the second power transistors;

or, the first bidirectional conversion circuit is a full-bridge topology circuit composed of positive integer multiples of 4 second power tubes.

3. The integrated charge-discharge system according to claim 2, wherein schottky diodes are connected in parallel between the sources and the drains of all the second power transistors in the first bidirectional converter circuit, and the conduction direction of the schottky diodes is opposite to the conduction current direction when the second power transistors are conducted.

4. The integrated charge-discharge system according to claim 1, further comprising an LC quasi-resonant circuit connected in series to a connection path of the high-frequency transformer and the second bidirectional conversion circuit, wherein an input terminal of the LC quasi-resonant circuit is connected to a secondary winding of the high-frequency transformer, and an output terminal of the LC quasi-resonant circuit is connected to a first terminal of the second bidirectional conversion circuit.

5. The integrated charge-discharge system according to claim 1, further comprising a multi-channel switch, wherein the secondary winding of the high-frequency transformer forms at least two secondary sub-windings through at least one tap, each secondary sub-winding is correspondingly connected with one LC quasi-resonant circuit, and the multi-channel switch switches the LC quasi-resonant circuits connected with different secondary sub-windings to be connected with the first end of the second bidirectional conversion circuit.

6. The charging and discharging integrated system according to claim 1, further comprising a first filter circuit connected in series to a connection path of the energy storage system and the first bidirectional conversion circuit, wherein a first end of the first filter circuit is connected to a charging and discharging end of the energy storage system, and a second end of the first filter circuit is connected to a first end of the first bidirectional conversion circuit;

and/or the inverter further comprises a second filter circuit connected with the second end of the second bidirectional conversion circuit, the first end of the second filter circuit is connected with the second end of the second bidirectional conversion circuit, and the first end of the second filter circuit is respectively connected with the inversion discharge output path and the alternating current charging input path.

7. The integrated charge-discharge system according to one of claims 1 to 6, wherein an inverter circuit, a first relay, a first EMC suppression circuit, a second relay and an AC output port are connected to the inverter discharge output path in this order;

the alternating current charging input path is sequentially connected with a rectifying circuit, a first relay, a first EMC (electro magnetic compatibility) suppression circuit, a second relay and an alternating current input port;

the inverter discharge output path and the alternating current charging input path share a first relay, a first EMC suppression circuit and a second relay, the first end of the first EMC suppression circuit is controlled by the first relay to be connected with the second end of the inverter circuit or the second end of the rectifying circuit, and the second end of the first EMC suppression circuit is controlled by the second relay to be connected with an alternating current output port or an alternating current input port.

8. The integrated charge-discharge system according to one of claims 1 to 6, wherein an inverter circuit, a first relay, a first EMC suppression circuit and an AC output port are connected to the inverter discharge output path in this order;

the alternating current charging input path is sequentially connected with a rectifying circuit, a first relay, a second EMC suppression circuit and an alternating current input port;

the inverter discharge output path and the alternating current charging input path share a first relay, and the first relay controls a first end of the first EMC suppression circuit to be connected with a second end of the inverter circuit or a second end of the rectifying circuit.

9. The integrated charge-discharge system according to one of claims 1 to 6, wherein a bidirectional inverter circuit, a first EMC suppression circuit, a second relay and an AC output port are connected to the inverter discharge output path in sequence;

the alternating current charging input path is sequentially connected with a bidirectional inverter circuit, a first EMC suppression circuit, a second relay and an alternating current input port;

the inverter discharge output path and the alternating current charging input path share a bidirectional inverter circuit, a first EMC suppression circuit and a second relay, and the second relay controls a second end of the first EMC suppression circuit to be connected with an alternating current output port or an alternating current input port;

the bidirectional inverter circuit is an H-bridge conversion circuit formed by four third power tubes.

10. The integrated charge and discharge system according to claim 9, further comprising an LC filter circuit, a first terminal of the LC filter circuit being connected to a second terminal of the bidirectional inverter circuit, a second terminal of the LC filter circuit being connected to a first terminal of the first EMC suppression circuit.

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