CN104796001B - Multiport converter and its power can expand platform - Google Patents

Abstract

The invention discloses a multi-port converter and a power expandable platform. The converter includes at least one input circuit, which is used for detachable electrical connection to the input source of the distributed energy; the output circuit, which is electrically connected with the input circuit, and is used for detachable electrical connection with the load; and the shunt regulation circuit, which is electrically connected with the input circuit for shunting Regulation; charge and discharge circuit, one end of which is electrically connected to the input circuit, and the other end is used for detachable electrical connection with a storage battery for energy storage; the input source supplies power to the output circuit, or the input source supplies power to the output circuit and is electrically connected to the charge and discharge circuit at the same time The battery of the circuit is charged, or the battery supplies power to the output circuit alone, or the input source and the battery jointly supply power to the output circuit. A single-stage power topology that can realize two or more inputs and one output can combine multiple distributed energy sources, reduce volume, improve power density and efficiency, and have better single-point failure performance. simpler.

Description

Multiport Converter and Its Power Scalable Platform

technical field

The invention relates to the technical field of power electronic converters, in particular to a multi-port converter and a power expandable platform thereof.

Background technique

In recent years, the urgent need for global energy conservation and emission reduction and the economic requirements of the carbon economic system, power generation technologies of solar energy, wind energy and other renewable and non-polluting resources, and their related energy conversion topologies and energy control strategies have become hot spots in social research Engineering and scientific issues.

There are many enterprises in Guangdong Province aiming at the development and application of new energy, and the industrial chain divisions are extensive and reasonable. From the selection and supply of devices for new energy applications, engineering production of new energy materials, R&D and design of new energy power converters and their energy control methods, there are related universities, research institutes and companies for R&D and industrial production.

Multi-port converter (Multi-port converter, MPC) is a typical new energy independent power generation system including energy storage. At present, the multi-port converter in the new energy industry in Shenzhen uses a single-port converter designed for easy engineering production. Direction and multi-direction DC/DC are effectively combined to realize a multi-port energy solution for system energy management and control. But there are the following problems in this solution: the number of power converters is large, the volume and weight are large, and there are multi-level power Transformation, low system efficiency, etc.

Contents of the invention

To solve the above technical problems, the present invention provides a multi-port converter and its power expandable platform, which can realize a single-stage power topology with two or more inputs and one output, can combine multiple distributed energy sources, and reduce the Smaller size, improved power density and efficiency, better single point failure performance, and easier maintenance.

In order to solve the above technical problems, the present invention provides a multi-port converter, comprising: at least one input circuit, used for detachable electrical connection to the input source of distributed energy; an output circuit, electrically connected to the input circuit for detachable Electrically connected to the load; a shunt adjustment circuit, electrically connected to the input circuit for shunt adjustment; a charging and discharging circuit, one end of which is electrically connected to the input circuit, and the other end is used for detachable electrical connection to a storage battery for energy storage; Under command control, the input source supplies power to the output circuit through the input circuit, or the input source supplies power to the output circuit through the input circuit and at the same time supplies power to the storage battery electrically connected to the charging and discharging circuit. Charging, or the storage battery supplies power to the output circuit solely through the charging and discharging circuit, or the input source jointly supplies power to the output circuit through the input circuit and the storage battery through the charging and discharging circuit.

Further, the charging and discharging circuit includes at least one first MOSFET, a third MOSFET and a battery connection terminal; the source of the first MOSFET is electrically connected to the input circuit, and the first MOSFET The drain of the tube is electrically connected to the drain of the third MOSFET tube, and the source of the third MOSFET tube is electrically connected to the battery connection terminal.

Further, a second MOSFET is provided between the input circuit and the shunt adjustment circuit, the source of the second MOSFET is electrically connected to the shunt adjustment circuit, and the drain of the second MOSFET is electrically connected to the input circuit.

Further, the multi-port converter includes a transformer, the transformer includes a primary coil, a secondary coil and a magnetic core; the primary coil is used as the shunt regulator circuit, and one end of the primary coil is electrically connected to the second The source and the other end of the MOSFET tube are grounded; the secondary coil is used as a part of the charging and discharging circuit, and both ends of the secondary coil are electrically connected to the first MOSFET tube and the third MOSFET tube respectively. between the drains; wherein, the shunt regulating circuit and the charging and discharging circuit are coupled through the transformer to facilitate energy storage and freewheeling.

Further, the turns ratio of the primary coil to the secondary coil is 1:1.

Further, the multi-port converter includes two or more than two input circuits, and each of the input circuits is electrically connected to the same output circuit, the shunt regulation circuit and the charging and discharging circuit, wherein Each of the input circuits and the charging and discharging circuit is provided with a secondary coil, and each of the secondary coils is coupled to the primary coil.

Further, the number of turns of each secondary coil is the same.

Further, each of the input circuits includes an input port and a first diode, and the output circuit includes an output port and a second diode; in the same input circuit, the anode of the first diode is electrically connected to In the input port, the cathode of the first diode is electrically connected to the source of the first MOSFET; the anode of the second diode is electrically connected to the drain and cathode of the second MOSFET the output port.

Further, the source of the third MOSFET is electrically connected to a first capacitor with one end grounded, and the cathode of the second diode is electrically connected to a second capacitor with one end grounded.

In order to solve the above technical problems, the present invention also provides a power expandable platform, comprising a plurality of multi-port converters as described in any one of the above-mentioned implementation modes, and each of the multi-port converters is arranged in parallel.

The multi-port converter and its power expandable platform of the present invention: By adopting a single-stage power circuit, the shunt regulation circuit and the battery charging and discharging circuit are effectively combined, redundant components are removed, and the volume of the existing converter is solved. Large, low power density and other issues, improve the conversion efficiency of the converter, and easy to expand. Moreover, the charging energy source of the multi-port converter can be the PV1 or PV2 array as an example above, so the charging efficiency of the whole machine is higher than that of the PCU with the S3R power regulation structure in the prior art, and the parallel structure of its modules is consistent with each other. Better single-point-of-failure performance and simpler equipment maintenance.

Description of drawings

FIG. 1 is a schematic diagram of functional modules of an embodiment of a multi-port converter of the present invention.

FIG. 2 is a schematic diagram of the circuit structure of an embodiment of the multi-port converter of the present invention.

3-9 are schematic structural diagrams of the working state 1-state 7 of the equivalent circuit of the multi-port converter shown in FIG. 2 .

Figure 10 is the time-domain waveform of the multi-port converter shown in Figure 2 in Boost-BCR mode (taking PV1 as an example).

Figure 11 is the time-domain waveform of the multi-port converter shown in Figure 2 in Buck-BDR mode (taking PV1 as an example).

Figure 12 is the time-domain waveform of the multi-port converter shown in Figure 2 in SR mode (taking PV1 as an example).

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Referring to Fig. 1, the multi-port converter of the embodiment of the present invention comprises the following structure:

The input circuit 1 is used for detachably electrically connecting the input source PV1 of the distributed energy source. Specifically, the distributed energy source may be a photovoltaic array, a fan, a water turbine, etc., and the following will take the photovoltaic array connected to one of the input circuits 1 as an example to describe in detail.

The output circuit 3 is electrically connected with the input circuit 1 for detachable electrical connection with the load 4 .

The shunt adjustment circuit 5 is electrically connected to the input circuit 1 for shunt adjustment.

One end of the charge and discharge circuit 6 is electrically connected to the input circuit 1, and the other end (namely P4) is used for detachable electrical connection with the battery 7. The battery 7 can be charged and stored or discharged to ensure the normal operation of the load 4.

Among them, under the command control, the following four working modes can be realized: the input source PV1 supplies power to the output circuit 3 through the input circuit 1, or the input source PV1 supplies power to the output circuit 3 through the input circuit 1 and is electrically connected to the charging and discharging circuit at the same time. The storage battery 7 of 6 is charged, or the storage battery 7 supplies power to the output circuit 3 through the charging and discharging circuit 6 alone, or the input source PV1 supplies power to the output circuit 3 through the input circuit 1 and the storage battery 7 through the charging and discharging circuit 6 jointly.

Referring to FIG. 2 , the charging and discharging circuit 6 includes at least one first MOSFET S1 , one third MOSFET S3 and a battery connection terminal P4 . Wherein, the source of the first MOSFET S1 is electrically connected to the input circuit 1, the drain of the first MOSFET S1 is electrically connected to the drain of the third MOSFET S3, and the source of the third MOSFET S3 is connected to the battery Terminal P4 is electrically connected. Further, a second MOSFET S2 is provided between the input circuit 1 and the shunt adjustment circuit 5 , the source of the second MOSFET S2 is electrically connected to the shunt adjustment circuit 5 , and the drain of the second MOSFET S2 is electrically connected to the input circuit 1 . Specifically, each MOSFET tube S1, S2, S3 includes a body parasitic diode D1, D2, D3 of its own. Equivalently, the anode of each body parasitic diode is electrically connected to the source of the MOSFET tube, and each body The cathode of the parasitic diode is electrically connected to the drain of the MOSFET. Through the setting of the first, second and third MOSFET tubes S1, S2 and S3, zero current (ZCS) turn-on can be realized when dynamically switching to the corresponding working mode.

In a preferred embodiment, the multi-port converter 100 includes a transformer T, and the transformer T includes a primary coil L1, a secondary coil L2 and a magnetic core (not marked); the primary coil L1 is used as a shunt regulator circuit 5, and one end of the primary coil L1 The source electrode of the second MOSFET tube S2 is electrically connected, and the other end is grounded; the secondary coil L2 is used as a part of the charging and discharging circuit 6, and the two ends of the secondary coil L2 are respectively electrically connected to the first MOSFET tube S1 and the third MOSFET tube S3. between the drains. Among them, the shunt regulating circuit 5 and the charging and discharging circuit 6 are coupled through the transformer T to facilitate energy storage and freewheeling, which can improve the efficiency and stability of a single module, and is easy to expand. Preferably, the turns ratio of the primary coil L1 and the secondary coil L2 is 1:1, which can simplify the subsequent control of the current.

Among them, R _Lm and L _m shown in Figure 2 are the equivalent excitation inductance and resistance of the primary side of the transformer T (that is, the primary coil L1); R _b is the equivalent resistance of the battery. In order to ensure that the multi-port converter 100 can work in Boost-BCR working mode in subsequent use, the resistance value of the first resistor RL is much larger than the resistance value of the second resistor Rb. In specific work, when the second MOSFET tube S2 is turned on, PV1 (or/and PV2, etc.), L _m , and R _Lm form a loop, which can be shunted to consume energy on R _Lm . Of course, under normal circumstances, it is not necessary to shunt the current, but to store the surplus electric energy in the storage battery 7 through the charging and discharging circuit 6, thus, a voltage detection circuit (not shown) can be set to measure the voltage of the storage battery 7 Then measure its power storage condition, and when it is detected that the storage battery 7 is full, the shunt regulation circuit is turned on by the internal or external controller to shunt the current.

In a preferred embodiment, referring to Fig. 1 and Fig. 2, the multi-port converter 100 includes two or more input circuits (1-N), and each input circuit (1-N) is electrically connected to the same output circuit 3. The shunt regulation circuit 5 and the charging and discharging circuit 6 . Among them, a secondary coil (L2, L3 as shown in Figure 2) is respectively arranged between each input circuit (1-N) and the charging and discharging circuit 6, and each secondary coil L2, L3 is coupled with the primary coil L1 . Preferably, the number of turns of each secondary coil is the same, for example, the ratio of the number of turns of the secondary coil L2 to the secondary coil L3 is 1:1, so that when there are multiple input sources, the control of the input current of each input source can be simplified . The multi-port converter 100 of this embodiment has two or more inputs, and can solve the problem of multiple input sources by adopting a topology structure, and is suitable for power generation access of multiple distributed energy sources. The single-stage power Higher topology efficiency and higher power density help reduce hardware costs.

In the full text, as shown in Figure 2, the number N of input circuits can take a value of 2. Correspondingly, two sets of photovoltaic arrays can be respectively used as the input source PV1, and the input source PV2 is correspondingly electrically connected to the input circuit 1 and the input circuit 2. .

In the above embodiments, the above-mentioned four working modes can be realized through the following example control methods. For the convenience of description, only the input circuit 1 connected to the input source PV1 is taken as an example for illustration.

1. Turn off the third MOSFET S3 and the second MOSFET S2 at the same time, so that the input source PV1 supplies power to the output circuit 3 through the input circuit 1 , that is, supplies power to the load 4 electrically connected to the output circuit 3 .

2. Turn off the second MOSFET S2 and turn on the third MOSFET S3, so that the input source PV1 supplies power to the output circuit 3 through the input circuit 1 and simultaneously charges the storage battery 7 electrically connected to the charging and discharging circuit 6 . When charging the battery 7 , the battery 7 can be charged in an MPPT (Maximum power point tracking, maximum power follow) mode.

3. Turn off the second MOSFET tube S2 and turn on the first MOSFET tube S1, and when the input circuit is not connected to the input source or the input source does not generate electric energy (such as the photovoltaic array in the shadow area), the battery 7 can be charged and discharged Circuit 6 supplies power to output circuit 3 alone.

4. Turn off the second MOSFET S2 and turn on the first MOSFET S1, so that the input source can supply power to the output circuit 3 through the input circuit and the battery 7 through the charging and discharging circuit 6 to meet the high power demand of the load 4 .

Of course, when there are multiple input sources, the specific control principle is similar to that described in 1 to 4 above.

In the above embodiments, refer to FIG. 3-FIG. 9 (they correspond to state 1-state 7 respectively), and the working principle of the multi-port converter 100 is briefly analyzed as follows (still taking PV1 as an example).

1) The PV1 array supplies power to the load 4, namely the SR (Shunt Regulator) mode and the PV1 array Boost-BCR (Boost-Battery Charge) mode.

State 1: The solar cell array PV1 performs freewheeling discharge on the inductor current I _L2 through the body parasitic diode D1 of the first MOSFET S1, and the third MOSFET S3 is in the conduction state, and its working mode is Boost-BCR. As shown in FIG. 10 , the second MOSFET S2 is turned on before time t ₀ , and the PV1 array stores energy for the inductor L1 . At time t ₀ , the second MOSFET S2 is turned off, so from time t ₀ to time t ₁ , the inductor current conducts freewheeling charging through the body parasitic diode D1. From time _t1 to time _t2 , S1 is soft-opened. So state 1 works in Boost-BCR mode.

State 2: When the second MOSFET S2 is turned on, the PV1 stores energy on the inductor L1 (that is, the primary coil L1) or shunts current to the ground. At time _t2 , as shown in FIG. 10 , the first MOSFET S1 is turned off, but the charging current I _L2 is always charged through the body parasitic diode D1 of the first MOSFETS1. At time _t3 , the second MOSFET S2 is turned on so that the PV1 array starts to store energy or shunt current to the inductor L1.

State 3: Since the third MOSFET S3 is turned off, the PV1 array is in a state of supplying power to the load 4 (the current supplied to the load 4 is Ipv) or a shunt state.

Its steady-state waveform is shown in Figure 12. At this time, the MPC (that is, the multi-port converter) is in the shunt mode similar to the S3R circuit or the circuit in the independent mode.

2) The battery 7 supplies power to the load 4, that is, Buck-BDR (Buck-Battery Discharge) mode.

State 4: The inductor current continues to supply power to the load 4 through the body parasitic diode D2 of the second MOSFET S2, and the inductor current I _L1 decreases linearly. As shown in FIG. 11 , the second MOSFET S2 is turned off at time _t0 , and from time _t0 to time _t1 , the battery 7 supplies power to the load 4 through the body parasitic diode D2. At time _t1 , the first MOSFET S1 is turned on.

State 5: When the first MOSFET S1 is turned on, the inductor current I _L2 freewheels through the body parasitic diode D3 of the third MOSFET S3 to discharge the load 4 and store energy in the inductor. This is the Buck-BDR mode. As shown in FIG. 11 , from time _t1 to time _t2 , the first MOSFET S1 is in an on state, and during this period, the inductor current I _L2 increases linearly. At time _t2 , the first MOSFET S1 is turned off, and then the inductive current I _L1 freewheels through the body parasitic diode D2 of the second MOSFET S2. At time _t3 , S2 realizes soft opening.

3) The battery 7 and the solar photovoltaic array PV1 jointly supply power to the load 4.

State 6: When the first MOSFET S1 is turned on, the inductor current I _L2 freewheels through the body parasitic diode D3 of the third MOSFET S3 to discharge the load 4 and store energy in the inductor, which is the Buck-BDR mode at this time; and At the same time, the solar battery array PV1 supplies power to the load 4 through D4. In joint power supply mode, the BDR working mode is the same as state 4, except that there is an extra PV1 input.

State 7: The inductor current I _L1 supplies power to the load 4 through the body parasitic diode D2 of the second MOSFET S2 , and PV1 still supplies power to the load 4 through D4 at this time. Its freewheeling discharge operation is similar to state 4.

In a specific application embodiment, as shown in the figure, each input circuit 1, 2 includes an input port and a first diode D5, D6, and an output circuit 3 includes an output port and a second diode D7; in the same input circuit , the anodes of the first diodes D5 and D6 are electrically connected to the input ports P1 and P2 respectively, and the cathodes of the first diodes D5 and D6 are respectively electrically connected to the sources of the first MOSFETs S1 and S4; the second diode D7 The anode of the MOSFET is electrically connected to the drain of the second MOSFET S2, and the cathode is electrically connected to the output port P3. Wherein, the arrangement of the first diodes D5, D6 and the second diode D7 can ensure the unidirectional flow of energy, making the operation of the multi-port converter safer and more reliable. In addition, the source of the third MOSFET S3 is electrically connected to a first capacitor C ₁ with one end grounded, and the cathode of the second diode D7 is electrically connected to a second capacitor C ₂ with one end grounded. The setting of the first capacitor C ₁ can be It supports instantaneous large current discharge, and the _second capacitor C2 can stabilize the load voltage.

The multi-port converter 100 of the embodiment of the present invention can be applied to fields such as fuel cell power generation systems, independent photovoltaic power generation systems, hybrid energy storage systems, hybrid electric vehicles, and aerospace satellite power supply systems. 5. The charging and discharging circuit 6 of the storage battery 7 is effectively combined, redundant components are removed, the problems of large volume and low power density of the existing converter are solved, the conversion efficiency of the converter is improved, and it is easy to expand. Moreover, the charging energy source of the multi-port converter 100 can be the PV1 or PV2 array as an example above, so the charging efficiency of the whole machine is higher than that of the PCU with the S3R power regulation structure in the prior art, and the charging mode can be maximum power following It can be seen that the parallel structure with consistent modules has better single point failure performance and is simpler in equipment maintenance.

The present invention also provides a power expandable platform, including a plurality of multi-port converters 100 according to any one of the above-mentioned implementation manners, and each multi-port converter 100 is arranged in parallel. For the description of the multi-port converter 100 , please refer to the foregoing, and details will not be repeated here. Wherein, each multiport converter 100 can be stacked or tiled and integrated into a module to construct the platform. The expansion platform has the advantages of high integration, fewer components, small size, and simple and convenient use.

The above is only the embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technical fields, All are included in the scope of patent protection of the present invention in the same way.

Claims (9)

1. a kind of multiport converter, it is characterised in that including：

At least input circuit all the way, the input source for detachably electrically connecting distributed energy；

Output circuit, is electrically connected with the input circuit for detachably electrically connecting load；

Shunt regulating circuit, is electrically connected with the input circuit for carrying out shunt regulating；

Charge-discharge circuit, its one end is electrically connected with the input circuit, the other end is used to detachably electrically connect the storage for energy storage Battery；

Under instruction control, the input source is powered by the input circuit to the output circuit, or the input source By the input circuit be the output circuit power and simultaneously be electrically connected to the charge-discharge circuit battery charge, Either the battery by the charge-discharge circuit be individually for the output circuit power or the input source pass through it is described Input circuit and the battery are combined by the charge-discharge circuit powers to the output circuit；

The charge-discharge circuit includes at least one the first MOSFET pipes, a 3rd MOSFET pipe and a battery connection End；The source electrode of the first MOSFET pipes is corresponding to the input circuit to be electrically connected, the drain electrode of the first MOSFET pipes and institute The drain electrode electrical connection of the 3rd MOSFET pipes is stated, the source electrode of the 3rd MOSFET pipes is electrically connected with the battery connection end.

2. multiport converter according to claim 1, it is characterised in that：

The 2nd MOSFET pipes, the source of the 2nd MOSFET pipes are provided between the input circuit and the shunt regulating circuit Pole electrically connects the shunt regulating circuit, and the drain electrode of the 2nd MOSFET pipes electrically connects the input circuit.

3. multiport converter according to claim 2, it is characterised in that：

The multiport converter includes a transformer, and the transformer includes primary coil, secondary coil and magnetic core；

The primary coil is used as the shunt regulating circuit, and described primary coil one end electrically connects the 2nd MOSFET pipes Source electrode, other end ground connection；

The secondary coil is used as a part for the charge-discharge circuit, and the secondary coil two ends are electrically connected in described the One MOSFET is managed between the drain electrode of the 3rd MOSFET pipes；

Wherein, the shunt regulating circuit passes through described transformer coupled in order to energy storage and afterflow with the charge-discharge circuit.

4. multiport converter according to claim 3, it is characterised in that：

The turn ratio of the primary coil and the secondary coil is 1:1.

5. multiport converter according to claim 3, it is characterised in that：

The multiport converter includes the input circuit more than two-way and two-way, and each input circuit is electrically connected to The same output circuit, the shunt regulating circuit and the charge-discharge circuit, wherein, each input circuit fills with described Secondary coil described in one is provided between discharge circuit, each secondary coil is coupled with the primary coil.

6. multiport converter according to claim 5, it is characterised in that：

The number of turn of each secondary coil is identical.

7. multiport converter according to claim 5, it is characterised in that：

Each input circuit includes input port and the first diode, and the output circuit includes output port and the two or two pole Pipe；

In the same input circuit, the anode of first diode electrically connects the input port, first diode Negative electrode electrically connect the source electrodes of the first MOSFET pipes；The anode of second diode electrically connects the 2nd MOSFET pipes Drain electrode, negative electrode electrically connect the output port.

8. multiport converter according to claim 7, it is characterised in that：

The source electrode of the 3rd MOSFET pipes is electrically connected with the first electric capacity of one end ground connection, and the negative electrode of second diode is electrically connected It is connected to the second electric capacity of one end ground connection.

9. a kind of power can expand platform, it is characterised in that become including multiple multiports as described in claim any one of 1-8 Parallel operation, each multiport converter is arranged in parallel.