CN209200941U - Bidirectional DC-DC converter - Google Patents

Abstract

The utility model discloses a kind of bidirectional DC-DC converter, include: one first battery and one second battery, one first inductor and one second inductor, a first capacitor device and one second capacitor and there are first to fourth switching power devices, and using the total N line design of double cell group, wherein the tie point of the tie point of the first battery and the second battery, the tie point of the first switching power devices and the second switching power devices and first capacitor device and the second capacitor is the total N line.The utility model by adjusting topological structure circuit unit, it can realize that double cell group framework bi-directional DC-DC energy is converted, when the battery midpoint for working in battery discharge mode and working under battery charging mode according to user, total N line all maintains level equalization, improve total system stability, and can realize total battery applications, to promote battery utilization rate and power density.

Description

Bidirectional DC-DC converter

Technical field

The utility model relates to a kind of topological structure of bidirectional DC-DC converter that can be suitable for double cell group framework, The bidirectional DC-DC converter of the conversion function of double cell electric discharge and charging can be achieved.

Background technique

It is more wide with regard to DC-DC converter, that is, the application of DC-DC converter in existing field of power electronics It is general, rather than isolation type DC-DC converter.This is the high transformation efficiency, cost effective and then by universal due to DC-DC converter Using.Buck DC-DC converter (Buck) topology circuit structure and step-up dc-dc converter in existing technology (Boost) topology circuit structure, both are relatively conventional application.

However with the appearance of high power density concept, it is applied so that bidirectional DC-DC converter is suggested, so as to Obtain the realization of higher power density.Mainly battery is frequently applied to bidirectional DC-DC converter as main energy storage component In device, due to the high cost of battery, the application in common-battery pond is then increasingly favored by market, thus it is a kind of suitable it is necessary to propose The topology circuit structure of bidirectional DC-DC converter for double cell group framework, so as to realizing what battery discharge and battery charged Conversion function, and can realize total battery applications, to improve the utilization rate and system power-density of battery；So existing DC-DC The technology of converter, needs and necessity is improved.

Utility model content

The utility model relates to a kind of bidirectional DC-DC converters, can not expire for existing bidirectional DC-DC converter The application in sufficient common-battery pond, and then provide and a kind of with high power density and can realize that the bi-directional DC-DC of total battery applications design becomes Parallel operation.The bidirectional DC-DC converter circuit of the double cell group framework of the utility model, can be applicable to high frequency non-isolation type direct-current- Switching mode circuit is used as in DC converter.It can not only realize the bidirectional DC-DC converter of double cell group framework, while can realize Battery applications altogether, to promote battery utilization rate and power density, the direct current that especially can be applied to high-power double cell group becomes Parallel operation, to improve the use value of its battery.

A kind of bidirectional DC-DC converter described in the utility model, comprising: one first battery becomes for the bi-directional DC-DC First power supply of parallel operation；One first inductor, the first end of first inductor are coupled to the first of first battery End；One first switching power devices, the first end of first switching power devices are coupled to the second of first inductor End, the second end of first switching power devices are coupled to the second end of first battery；One third switching power devices, The second end of the third switching power devices is coupled to the second end of first inductor；One first capacitor device, described The first end of one capacitor is coupled to the first end of the third power switch, the second end of the first capacitor device and described the The second end of one battery；One first resistor device, the first resistor device are to be connected in parallel with the first capacitor device；One second electricity Pond, is the second power supply of the bidirectional DC-DC converter, and the first end of second battery is coupled to first battery Second end；One second switching power devices, the first end of second power switch are coupled to the first end of second battery； One second capacitor, the first end of second capacitor are coupled to the first end of second battery；One second resistor, institute It is to be connected in parallel that second resistor, which is stated, with second capacitor；One second inductor, the first end coupling of second inductor It is connected to the second end of second battery, the second end of second inductor is coupled to the of second switching power devices Two ends；And one the 4th switching power devices, the first end of the 4th switching power devices are coupled to second power switch The second end of the second end of component, the 4th switching power devices is coupled to the second end of second capacitor.

In one embodiment, first battery and the second battery are double cell group and are total N line；First battery The tie point of second end and the first end of second battery, and it is electric with described second with the second end of the first capacitor device The tie point of the first end of container is all the tie point of the total N line.

In one embodiment, when discharge condition, first battery passes through for first battery and second battery First inductor, first switching power devices and the third switching power devices are equivalent diode etc. The connection of circuit charges to the first capacitor device；And second battery is also through second inductor, described Two switching power devices and the 4th switching power devices are the connection of the circuits such as an equivalent diode, and to described the Two capacitors charge；And maintain the level equalization of the total N line.

When charged state, the first capacitor device passes through for first battery and second battery in one embodiment The third switching power devices, first switching power devices are an equivalent diode and described first inductor etc. The connection of circuit charges to first battery；Second capacitor passes through the 4th switching power devices, described second Switching power devices are the connection of the circuits such as an equivalent diode and second inductor, are filled to second battery Electricity；And maintain the level equalization of the total N line.

In one embodiment first to fourth switching power devices be MOSFET, IGBT of power-type, BJT, MOS, The switching molding group of CMOS, JFET or IGBT.

The first end of first battery and the first end of second battery in one embodiment, are all positive terminal；Institute The second end of the second end and second battery of stating the first battery is all negative pole end.

The first end of the first capacitor device and the first end of second capacitor in one embodiment are all anode End；The second end of the first capacitor device and the second end of second capacitor are all negative pole end；The first resistor device table It is shown as one first load；The second resistor is expressed as one second load.

The first end of first to fourth switching power devices is all drain electrode end in one embodiment；Described first to The second end of four switching power devices is all source terminal.

The anode of the equivalent diode of the third switching power devices in one embodiment, to be coupled to described first The cathode of the second end of inductor, the equivalent diode of the third switching power devices is then coupled to the first capacitor device First end；The anode of the equivalent diode of 4th switching power devices, for be coupled to second capacitor Two ends, and the cathode of the equivalent diode of the 4th switching power devices is then coupled to the second of second inductor End.

The anode of the equivalent diode of first switching power devices in one embodiment, to be coupled to described first The cathode of the second end of battery, the equivalent diode of first switching power devices is then coupled to first inductor Second end；The anode of the equivalent diode of second switching power devices, for be coupled to second inductor second End, and the cathode of the equivalent diode of second switching power devices is then coupled to the first end of second battery.

The utility model can realize the two-way DC- of double cell group framework by adjusting the circuit unit of topological structure The conversion of DC energy, when the battery midpoint for working in battery discharge mode and working under battery charging mode according to user, total N line all maintains electricity It is steady fixed, total system stability is improved, and can realize total battery applications, to promote battery utilization rate and power density.

Detailed description of the invention

Fig. 1 is the circuit topography connection schematic diagram of the utility model first embodiment；

Fig. 2 is double cell group in the utility model first embodiment in the schematic diagram of discharge condition；

Fig. 3 is double cell group in the utility model first embodiment in the schematic diagram of charged state；

Fig. 4 is the circuit unit connection schematic diagram of the utility model second embodiment；

Fig. 5 is the circuit unit connection schematic diagram of the utility model 3rd embodiment.

Specific embodiment

It hereinafter will be refering to alterations, so as to various exemplary embodiments are more fully described, and in alterations It is middle to show some exemplary embodiments.However, the concept of the utility model may be embodied in many different forms, and not It should be interpreted that and be only limitted to exemplary embodiments set forth herein.Specifically, these exemplary embodiments are provided and make this Utility model will be scope that is detailed and complete, and the utility model concept will sufficiently being conveyed to those who familiarize themselves with the technology.All In schema, circuit box, the size of circuit unit and opposite position can be lavished praise on oneself in order to clear, wherein for similar number Always similar assembly is indicated.

Although referring to it should be understood that may use term switch block system herein includes multiple switching power devices A kind of expression term of changeover module, but do not limit be using IGBT, BJT, MOS, CMOS, JFET or MOSFET, i.e., this Equal components should not be by the limitation of these electronic building brick actual product terms.And first to fourth power switch occurred herein To the inductor of C2 or the first to the second L1 to L2 ... etc., these terms are by component Q1 to Q4, the first to the second capacitor C1 To clearly distinguish a component and another component, not there is certain component priority order Rankine-Hugoniot relations, that is, be possible to have the One switch, third switch and the component without second switch implements kenel, are not necessarily having the serial number of serial relation as component The mark of symbol.

First end, second end, upper end or the lower end of term as used herein, left-hand end or right-hand end etc., these Term is another endpoint to clearly distinguish the end point of a component Yu the component, or for distinguish a component with it is another It is not to be between component or between an endpoint and another endpoint to limit the text serial number for difference Existing ordinal relation, and not necessarily has numerically continuous relationship；In addition, term " a plurality of " or " multiple " may be used herein To describe to have, multiple circuit units are set, but these plurality of element be not limited in being implemented with two, three or four and More than four component counts indicate implemented technology；More than, conjunction is first chatted bright.

The utility model discloses a kind of bidirectional DC-DC converter, connects by circuit unit set by the utility model It can be suitable for the topological structure of the bidirectional DC-DC converter of double cell group framework, it can be achieved that double cell electric discharge and turn to charge Function is changed, and can realize the application in common-battery pond, to improve the utilization rate of battery and the power density of system, i.e. the utility model The application that existing bidirectional DC-DC converter is unable to satisfy common-battery pond is efficiently solved, and then is provided a kind of close with high power Degree and the bidirectional DC-DC converter that can realize total battery applications design.

Fig. 1 show the circuit topology of bidirectional DC-DC converter described in the utility model, includes a plurality of electricity Pond, a plurality of inductors, plurality of capacitors and a plurality of switching power devices.Wherein, a plurality of batteries include One first battery BAT1 and one second battery BAT2；A plurality of inductors include the electricity of one first inductor L1 and one second Sensor L2；The plurality of capacitors includes a first capacitor device C1 and one second capacitor C2；A plurality of power Switch block then includes first to fourth switching power devices Q1 to Q4.

First battery BAT1 is first power supply of the bidirectional DC-DC converter, is the power source of a DC power supply； The first end of first inductor L1 is coupled to the first end of the first battery BAT1.As for the first inductor L1 first end refer to as The left end of first inductor L1 described in shown in Fig. 1, the second end of the first inductor L1 refer to the right side of the first inductor L1 Endpoint；And the first end of the first battery BAT1 is referring to the upper end of the first battery BAT1 in Fig. 1, and in practice, described the The first end of one battery BAT1 can be the positive terminal of a direct current battery power and the second end of the first battery BAT1 is the first electricity The lower end of pond BAT1 is the negative pole end of a battery in practice.

The first end of the first switching power devices Q1 is coupled to the second end of the first inductor L1, first power The second end of switch block Q1 is coupled to the second end of the first battery BAT1.Wherein the first end of the first switching power devices Q1 is Refer to the upper end of the first switching power devices Q1 described in Fig. 1, in one embodiment, if the first switching power devices Q1 is one When MOSFET component, then the first end of the first switching power devices Q1 is a drain electrode end (Drain)；And the first power is opened The second end for closing component Q1 refers to the lower end of the first switching power devices Q1 described in Fig. 1；As for the first switching power devices Q1 In in practice, component can be the components such as IGBT, BJT, MOS, CMOS, JFET or MOSFET or IGBT Switching molding group, but these sixth types are not limited to, the scope of the utility model is simultaneously without restriction.Likewise, in one embodiment When the first switching power devices Q1 is a MOSFET component, at this point, the second end of the first switching power devices Q1 is one Lower end, and can be source-side (Source).In addition, when the first switching power devices Q1 is a MOSFET component, described the For one switching power devices Q1 there are also a gate terminal (Gate), the gate terminal is the first switching power devices Q1 control conducting Or the endpoint of cut-off, and the gate terminal is coupled with a control circuit (not shown), so as to controlling first power switch The movement of component Q1, however, the utility model is mainly circuit topology as shown in Figures 1 to 5, with switching power devices Then it will not go into details for relevant control circuit.

The second end of the third switching power devices Q3 is coupled to the second end of the first inductor L1；Wherein third power The second end of switch block Q3 refers to the left end of the Q3 of third switching power devices described in Fig. 1.In one embodiment, if third function When rate switch block Q3 is a MOSFET component, then the second end of third switching power devices Q3 is source-side (Source).On the other hand, the first end of third switching power devices Q3 refers to the Q3's of third switching power devices described in Fig. 1 Right end, as third switching power devices Q3 in practice, component can for IGBT, BJT, MOS, CMOS, JFET or It is the components such as MOSFET or the switching molding group of IGBT, but is not limited to these sixth types, the scope of the utility model is simultaneously not added With limitation.Likewise, in one embodiment when third switching power devices Q3 is a MOSFET component, at this point, the third The first end of switching power devices Q3 is right end, and can be a drain electrode end (Drain).In addition when third switching power devices Q3 is When one MOSFET component, for the third switching power devices Q3 there are also a gate terminal, the gate terminal is that the third power is opened Endpoint of the component Q3 to control on or off is closed, and the gate terminal is coupled with a control circuit (not shown), so as to The movement of the third switching power devices Q3 is controlled, however, the utility model is mainly that circuit as shown in Figures 1 to 5 is opened up Plain structure, then it will not go into details for control circuit relevant to switching power devices.

The first capacitor device C1 has a first end and a second end, and the first end of first capacitor device C1 as shown in Figure 1 is Upper end, the second end of first capacitor device C1 are lower end.Wherein the first end of the first capacitor device C1 is coupled to third power and opens Close the first end (drain electrode end) of Q3；The second end of the first capacitor device C1 then with the second end (negative pole end) of the first battery BAT1 Mutually couple, and the second end of the first capacitor device C1 also with second end (source terminal) phase of the first switching power devices Q1 Coupling.In one embodiment, the first end of first capacitor device C1 is a positive terminal；The second end of first capacitor device C1 is a cathode End.

The second battery BAT2 is the power supply of second direct current form of the bidirectional DC-DC converter, the second electricity The first end of pond BAT2 is coupled to the second end of the first battery BAT1；The first end of second battery BAT2 is referring to second in Fig. 1 The upper end of battery BAT2, in practice, the first end of the second battery BAT2 can be the anode of galvanic battery power supply always The second end of end and the second battery BAT2 are the lower end of the second battery BATB, are a negative pole end.By the first battery BAT1 with And second battery BAT2 connection, formed have altogether battery design and be double cell group bidirectional DC-DC converter.

The first end of the second switching power devices Q2 is coupled to the first end of the second battery BAT2；About the second power The first end of switch block Q2 refers to the upper end of the second switching power devices Q2 described in Fig. 1.Separately in one embodiment, if second When switching power devices Q2 is a MOSFET component, then the first end of the second switching power devices Q2 is a drain electrode end (Drain), opposite, the second end of the second switching power devices Q2 refers under the second switching power devices Q2 described in Fig. 1 End is source-side (Source).As for the second switching power devices Q2 in practice, component can for IGBT, The switching molding group of the components such as BJT, MOS, CMOS, JFET or MOSFET or IGBT, but these sixth types are not limited to, this is practical Novel practical range is simultaneously without restriction.In addition, when the second switching power devices Q2 is a MOSFET component, described second For switching power devices Q2 there are also a gate terminal, the gate terminal is that the second switching power devices Q2 is used to control conducting or cuts Endpoint only, and the gate terminal is coupled with a control circuit (not shown), so as to controlling second switching power devices The movement of Q2, however, the utility model is mainly circuit topology as shown in Figures 1 to 5, it is related to switching power devices Control circuit then it will not go into details.

The first end of the second capacitor C2 is coupled to the first end of the second battery BAT2；As shown in Figure 1, the second capacitor The first end of device C2 is upper end, and the second end of the second capacitor C2 is lower end.Wherein the first end of the second capacitor C2 is same When be coupled to the first end (drain electrode end) of the second power switch Q2.In one embodiment, the first end of the second capacitor C2 is one Positive terminal；The second end of second capacitor C2 is a negative pole end.

The first end of the second inductor L2 is coupled to the second end of the second battery BAT2, and the second of the second inductor L2 End is then coupled to the second end (source terminal) of the second switching power devices Q2.Wherein the first end of the second inductor L2 is as schemed 1 show the left end of the second inductor L2, and the second end of the second inductor L2 is right end.

The first end of the 4th switching power devices Q4 is coupled to the second end of the second switching power devices Q2, and described The second end of four switching power devices Q4 is coupled to the second end of the second inductor C2.Wherein the 4th switching power devices Q4 First end refer to the left end of the 4th switching power devices Q4 described in Fig. 1.In one embodiment, if the 4th switching power devices When Q4 is a MOSFET component, then the first end of the 4th switching power devices Q4 is drain electrode end (Drain), the 4th power switch group The second end of part Q4 is right end and is source-side (Source).4th switching power devices Q4 is in practice, component It can be the components such as IGBT, BJT, MOS, CMOS, JFET or MOSFET or the switching molding group of IGBT, but be not limited to this Six classes, the scope of the utility model are simultaneously without restriction.In addition, when the 4th switching power devices Q4 is a MOSFET component When, the 4th switching power devices Q4 there are also a gate terminal, the gate terminal be the 4th switching power devices Q4 to The endpoint of on or off is controlled, and the gate terminal is coupled with a control circuit (not shown), so as to control the described 4th The movement of switching power devices Q4, however, the utility model is mainly circuit topology as shown in Figures 1 to 5, with power Then it will not go into details for the relevant control circuit of switch block.

Shown in Fig. 1, the connection of the first battery BAT1 and the second battery BAT2 are the circuit structure of double cell group, and For total N line.The wherein tie point of the second end of the first battery BAT1 and the first end of the second battery BAT2, the first power switch group The tie point of part Q1 and the second switching power devices Q2, and the tie point with first capacitor device C1 and the second capacitor C2, etc. Three contacts are all the tie point of the total N line.In practice, the total N line is a neutral conductor.

Among the above, the revealed circuit topography framework of Fig. 1 the utility model is designed using the total N line of double cell group, first To the 4th switching power devices Q1 to Q4 when switching the different conditions of charge/discharge, schools can be waited for diode use, pass through tune The duty cycle ratio (duty ratio) for the control circuit that whole gate terminal (Gate) is connected, can be realized electric current two-way flow.And And the bidirectional DC-DC converter circuit of the double cell group framework can be applicable to high frequency non-isolation type direct-current-DC converter The middle circuit structure as switching mode.In addition, the first to fourth switching power devices Q1 to Q4 is the function for full-control type Rate switch block, including power MOSFET, power-type IGBT, high-power IGBT module etc., but it is not limited to these three types.

It is when the circuit of bidirectional DC-DC converter applies the equivalent topologies circuit under battery discharge status shown in Fig. 2 Figure, as shown in Figure 2.Wherein the first battery BAT1 and the second battery BAT2 be when discharge condition, then the first battery BAT1 passes through the One inductor L1, the first switching power devices Q1 and the third switching power devices Q3 become an equivalent diode, i.e., For the connection of the circuits such as a third equivalent diode D3, execution charges to first capacitor device C1.On the other hand, the second battery BAT2 is one equivalent also through the second inductor L2, the second switching power devices Q2 and the 4th switching power devices Q4 Diode, the as connection of the circuits such as one the 4th equivalent diode D4, and the second capacitor C2 is charged and supplied Electric energy；Meanwhile and maintain integrated circuit system double cell group the total N line level equalization, be effectively reduced system high-frequency The interference of signal.

In Fig. 2, the anode of the third switching power devices Q3 equivalent third equivalent diode D3, to be coupled to The second end of one inductor L1, the cathode of third switching power devices Q3 equivalent third equivalent diode D3 are then coupled to The first end of one capacitor C1.The anode of the 4th 4th switching power devices Q4 equivalent equivalent diode D4, to be coupled to The second end of second capacitor C2, the cathode of the 4th the 4th switching power devices Q4 equivalent equivalent diode D4 are then coupled to The second end of second inductor L2.

Fig. 3 is when the circuit of bidirectional DC-DC converter applies the equivalent topologies circuit diagram under battery charging state, as schemed Shown in 3.Wherein when charged state, then the first capacitor device C1 passes through third function by the first battery BAT1 and the second battery BAT2 Rate switch block Q3, the first switching power devices Q1 control are an equivalent diode, as the first equivalent diode D1 And first the interlock circuits such as inductor L1 connection, execute and charge to the first battery BAT1.Likewise, the second capacitor C2 is an equivalent diode by the 4th switching power devices Q4, the second switching power devices Q2, and as second is equivalent The connection of the interlock circuits such as diode D2 and the second inductor L2 charges to the second battery BAT2；And maintain the total N The level equalization of line, and in integrated circuit system capacitor midpoint level equalization, the high frequency of circuit system can be effectively reduced Signal interference.

The anode of the first first switching power devices Q1 equivalent equivalent diode D1 in Fig. 3, to be coupled to described The cathode of the second end of one battery BAT1, the first the first switching power devices Q1 equivalent equivalent diode D1 then couples In the second end of the first inductor L1.In addition, the anode of the second the second switching power devices Q2 equivalent equivalent diode D2, For the second end for being coupled to the second inductor L2, and the second the second switching power devices Q2 equivalent equivalent diode D2 Cathode be then coupled to the first end of the second battery BAT2.

Fig. 4 is the topology circuit structure connection figure of the utility model second embodiment, second embodiment and first embodiment Main difference be in the second embodiment that the first capacitor device C1 is connected in parallel to a first resistor device R1, The both ends of two capacitor C2 are connected in parallel to second resistor a R2, the first resistor device R1 and second resistor R2 can be a It is not expressed as institute on the load end (first capacitor device C1 and the second end capacitor C2) of the bidirectional DC-DC converter of the utility model Other circuits of connection, or indicate that a kind of equivalent circuit of load indicates.In addition, the first resistor device R1 and second resistance Device R2 can also indicate the integrated circuit equivalent resistance for seeing access point to the left by the first resistor device R1 and second resistor R2 Device.

Fig. 5 is shown by the further derivative embodiment of the second embodiment institute, that is, the first capacitor device C1 It is connected in parallel to one first load 10, the both ends of the second capacitor C2 are connected in parallel to one second load 20, first load 10 i.e. the second load 20 can be further used as the different application embodiment of the bidirectional DC-DC converter driving load.

In conclusion the utility model proposes a kind of bidirectional DC-DC converter, can by adjusting topological structure component with Related device can realize that double cell group framework bi-directional DC-DC energy is converted, and topological structure works in battery discharge mode Stabilization of level can be maintained with the total N line in battery midpoint worked under battery charging mode according to user, significantly improves whole system System stability, and can realize the circuit framework of total battery applications.And the actual effect of the utility model is to realize double cell group The bidirectional DC-DC converter of framework, while total battery applications also may be implemented, and promote battery utilization rate and power density.This Utility model is reliably easy, can apply to DC converter and improve power density, especially can be applied to powerful double The DC converter of battery pack, to improve the use value of its battery.Obvious, the utility model is great wanting for patent application Part.

However, described in the utility model description, only preferred embodiment for example, practical when that cannot limit Novel protected range, any local variation, amendment or increased technology, the range protected without departing from the utility model In.

Claims (10)

1. a kind of bidirectional DC-DC converter characterized by comprising

One first battery is first power supply of the bidirectional DC-DC converter；

One first inductor, the first end of first inductor are coupled to the first end of first battery；

One first switching power devices, the first end of first switching power devices are coupled to the second of first inductor End, the second end of first switching power devices are coupled to the second end of first battery；

One third switching power devices, the second end of the third switching power devices are coupled to the second of first inductor End；

One first capacitor device, the first end of the first capacitor device are coupled to the first end of the third switching power devices, institute The second end for stating first capacitor device is coupled to the second end of first battery；

One first resistor device, the first resistor device are to be connected in parallel with the first capacitor device；

One second battery, is the second power supply of the bidirectional DC-DC converter, and the first end of second battery is coupled to institute State the second end of the first battery；

One second switching power devices, the first end of second switching power devices are coupled to the first of second battery End；

One second capacitor, the first end of second capacitor are coupled to the first end of second battery；

One second resistor, the second resistor are to be connected in parallel with second capacitor；

One second inductor, the first end of second inductor are coupled to the second end of second battery, second electricity The second end of sensor is coupled to the second end of second switching power devices；And

The first end of one the 4th switching power devices, the 4th switching power devices is coupled to second switching power devices Second end, the second end of the 4th switching power devices is coupled to the second end of second capacitor.

2. bidirectional DC-DC converter as described in claim 1, which is characterized in that first battery and the second battery are double Battery pack and be total N line；The tie point of the first end of the second end of first battery and second battery, and with it is described The tie point of the second end of first capacitor device and the first end of second capacitor, is all the tie point of the total N line.

3. bidirectional DC-DC converter as claimed in claim 2, which is characterized in that first battery and second battery When discharge condition, first battery is equivalent by first inductor, first switching power devices and for one Diode the third switching power devices circuit connection, charge to the first capacitor device；And described second Battery is also by second inductor, second switching power devices and is the 4th function of an equivalent diode The circuit connection of rate switch block, and charge to second capacitor；And maintain the level equalization of the total N line.

4. bidirectional DC-DC converter as claimed in claim 2, which is characterized in that first battery and second battery When charged state, the first capacitor device by the third switching power devices, be described the of an equivalent diode The circuit connection of one switching power devices and first inductor charges to first battery；Second capacitor By the 4th switching power devices, for an equivalent diode second switching power devices and it is described second electricity The circuit connection of sensor charges to second battery；And maintain the level equalization of the total N line.

5. bidirectional DC-DC converter as described in claim 1, which is characterized in that first switching power devices to the 4th The switching molding group that switching power devices are MOSFET, IGBT, BJT, MOS, CMOS, JFET or IGBT of power-type.

6. bidirectional DC-DC converter as described in claim 1, which is characterized in that the first end of first battery and described The first end of second battery is all positive terminal；The second end of first battery and the second end of second battery are all negative Extremely.

7. bidirectional DC-DC converter as described in claim 1, which is characterized in that the first end of the first capacitor device and The first end of second capacitor, is all positive terminal；The of the second end of the first capacitor device and second capacitor Two ends are all negative pole end；The first resistor device is expressed as one first load；The second resistor is expressed as one second load.

8. bidirectional DC-DC converter as described in claim 1, which is characterized in that the first of first switching power devices Holding the first end to the 4th switching power devices is all drain electrode end；The second end of first switching power devices is to the 4th power The second end of switch block is all source terminal.

9. bidirectional DC-DC converter as claimed in claim 3, which is characterized in that the third switching power devices institute is equivalent Diode anode, for the second end for being coupled to first inductor, the third switching power devices it is equivalent two The cathode of pole pipe is then coupled to the first end of the first capacitor device；The equivalent diode of 4th switching power devices Anode, for the second end for being coupled to second capacitor, the cathode of the equivalent diode of the 4th switching power devices Then it is coupled to the second end of second inductor.

10. bidirectional DC-DC converter as claimed in claim 4, which is characterized in that the first switching power devices institute is equivalent Diode anode, for the second end for being coupled to first battery, two equivalent poles of first switching power devices The cathode of pipe is then coupled to the second end of first inductor；The sun of the equivalent diode of second switching power devices Pole, for the second end for being coupled to second inductor, the cathode of the equivalent diode of second switching power devices is then It is coupled to the first end of second battery.