CN105048816B - DC DC converters - Google Patents

Abstract

No matter the present invention provides the vehicle for how providing the amount of electric power supply of load efficient DC DC converters and can realizing the efficient power supply to load.In situation of the amount of electric power supply more than setting to loading (R1), control unit (5) performs the first mode of driving switch element (Si~S4), in situation of the amount of electric power supply below setting to loading (R1), control unit (5) performs second mode, in this second mode, switch element S3, S4 is set to stop in the off state, and only driving switch element S1, S2.

Description

DC-DC converter

The application is the Shen of entitled " DC-DC converter " that is proposed to China State Intellectual Property Office on June 25th, 2010 Please No：201080067480.3 divisional application.

Technical field

The present invention relates to the DC-DC converter with insulation function.

Background technology

Known DC-DC converter is following device：By DC power conversion it is alternating current by on-off circuit, uses Transformer carries out transformation to the alternating current, and is transformed it into direct current by rectification circuit and exported.Big in the electric power of processing In the case of generally use full-bridge circuit.In the full-bridge circuit, the switch element of two pairs of switch element upper arm sides being connected in series With the switch element driven of underarm side.It is, the switch element of upper arm side and the switch element of underarm side are carried out mutually Opposite open and close driving.But big switching losses are produced as hard switching when the unlatching of switch element, shut-off, and And inefficient.

Therefore, reduction switching losses are disclosed in patent document 1 and realizes the improved DC-DC converter of efficiency.The DC- DC converters make the open and close driving for the switch element being connected in series and being connected in series for the opposing party of a side of composition full-bridge circuit Switch element open and close driving phase offset and be operated.Thus, ZVT can be turned into, and switch can be realized The reduction of loss.The control mode is referred to as phase-shifted manner.

In addition, disclose following content in patent document 2：It is complete by making when load lightens in the circuit of mode of resonance One side of one group of switch of bridge circuit continues to turn on, and makes a side continue to turn off, and realizes that efficiency improves the reduction with output pulsation.

Prior art literature

Patent document

Patent document 1：Japanese Patent Laid-Open 2003-47245 publications

Patent document 2：Japanese Patent Laid-Open 2003-324956 publications

The content of the invention

The technical task that invention will solve

The full-bridge circuit of phase-shifted manner can carry out ZVT when the amount of electric power supply to load is more, but to negative When the amount of electric power supply of load is few, the electric current for flowing through circuit tails off, the when anaplasia of the discharge and recharge needs of the parasitic capacitance of switch element It is long.When the incomplete switch element of the discharge and recharge is opened, turn into hard switching, the problem of switching losses increase, efficiency decline be present.

In addition, in the full-bridge circuit of phase-shifted manner, relative to the discharge and recharge of the parasitic capacitance using switch element, resonance The circuit of type is FREQUENCY CONTROL,, can not be in phase even if the problem to be solved is identical because operating principle originally differs The technology for the circuit that can be applied to mode of resonance is applicable in the circuit of shifting mode.

No matter the purpose of the present invention is how all to provide efficient DC-DC converter to the amount of electric power supply of load.

Further it is an object to following vehicle：No matter how can be real to the amount of electric power supply of load Now to the efficient power supply of load.

Means for solving the problems

To achieve these goals, DC-DC converter of the present invention, it is characterised in that have：Full-bridge circuit, by By first, second switch elements in series connection first switch branch and by the three, the 4th switch elements in series connect and with it is described The second switch branch that first switch branch is connected in parallel is formed, by between the first switch branch both ends and second switch branch both ends Between be set between DC terminal, by being connected in series a little and the three, the 4th switch element for first, second switch element It is set between being connected in series a little between ac terminal；Rectification circuit with smooth reactor；First smoothing capacity device, with direct current Source is connected in parallel, and is connected between the DC terminal of the full-bridge circuit；Second smoothing capacity device, and load parallel connection, And it is connected between the DC terminal of the rectification circuit；Armature winding, it is connected between the ac terminal of the full-bridge circuit；It is secondary Level winding, is connected between the ac terminal of the rectification circuit；Transformer, the armature winding and the secondary windings are carried out Magnetic coupling；And control unit, the full-bridge circuit is controlled, the described 1st, the 2nd, the 3rd, the 4th switch element respectively by Switch, the anti-parallel diodes that are connected with the switch in parallel and with it is described switch and the anti-parallel diodes simultaneously The capacitor of connection connection is formed, the DC-DC converter have between the ac terminal of the full-bridge circuit and it is described it is primary around Connected between group the reactor composition of insertion, wherein, when the amount of electric power supply to the load is more than setting, the control Unit processed perform driving it is described 1st, the 2nd, the 3rd, the first mode of the 4th switch element, in the amount of electric power supply to the load When below the setting, described control unit performs second mode, in this second mode：Make the composition first switch One group of switch element of the switch branch of the side of branch or second switch branch stops in the off state, and drives composition described first One group of switch element of the switch branch of the opposite side of switch branch or second switch branch.

In addition, vehicle for the present invention is characterised by being equipped with the DC-DC converter of the present invention.

The effect of invention

According to the present invention, no matter how all to provide efficient DC-DC converter to the amount of electric power supply of load.

In addition, according to the present invention, regardless of the amount of electric power supply to load, can provide can realize to load The vehicle of efficient power supply.

Brief description of the drawings

Fig. 1 is the circuit structure diagram of 1 DC-DC converter according to an embodiment of the invention.

Fig. 2 is the figure of the switching for the operator scheme for illustrating embodiment 1.

Fig. 3 is the figure of the determining method for the setting Pth for illustrating embodiment 1.

Fig. 4 is the figure of the switching for the operator scheme for illustrating 2 settings Pth1, Pth2 based on embodiment 1.

Fig. 5 is voltage, the current waveform figure of the action under the light load mode M2 for illustrating embodiment 1.

Fig. 6 is the action (pattern a) circuit diagram under the light load mode M2 of (a) during Fig. 5 is shown.

Fig. 7 be illustrate Fig. 5 show during (b) light load mode M2 under action (pattern b) circuit diagram.

Fig. 8 be illustrate Fig. 5 show during (c) light load mode M2 under action (pattern c) circuit diagram.

Fig. 9 be illustrate Fig. 5 show during (d) light load mode M2 under action (pattern d) circuit diagram.

Figure 10 be illustrate Fig. 5 show during (e) light load mode M2 under action (pattern e) circuit diagram.

Figure 11 be illustrate Fig. 5 show during (f) light load mode M2 under action (pattern f) circuit diagram.

Figure 12 be illustrate Fig. 5 show during (g) light load mode M2 under action (pattern g) circuit diagram.

Figure 13 be illustrate Fig. 5 show during (h) light load mode M2 under action (pattern h) circuit diagram.

Figure 14 is the voltage oscillogram of the other action under the light load mode M2 for illustrating embodiment 1.

Figure 15 is the circuit structure diagram for the DC-DC converter for illustrating embodiments of the invention 2.

Figure 16 is the circuit structure diagram for the DC-DC converter for illustrating embodiments of the invention 3.

Figure 17 is the sketch structure figure of the power-supply system of conventional electric automobile.

Figure 18 is the sketch structure figure of the power-supply system of the electric automobile of embodiments of the invention 4.

Embodiment

On embodiments of the present invention, reference picture is described in detail.In addition, in the following description, will be with connection The voltage of the switch element of state or it is equal with the positive drop-out voltage for the anti-parallel diodes that switch element is connected in parallel or Voltage below it is referred to as no-voltage, in the state of being no-voltage in the voltage applied to switch element, switches this and opens Close element be switched on and off be referred to as ZVT or Sofe Switch to reduce switching losses.

【Embodiment 1】

Fig. 1 is according to an embodiment of the invention 1 circuit structure diagram of DC-DC converter 1.The DC-DC converter 1 is to direct current Power supply V1, which carries out transformation, to be come to loading R1 supply electric powers.In addition, dc source V1 can also be replaced into power factor correction circuit Etc. the output of other converters.

In Fig. 1, dc source V1 and smoothing capacity device C1 are connected between the DC terminal A-A ' of full-bridge circuit 2. Smoothing capacity device C2 and load R1 are connected between the DC terminal B-B ' of rectification circuit 7.In the ac terminal of full-bridge circuit 2 Armature winding N1 is connected between C-C ', secondary windings N2 is connected between the ac terminal D-D ' of rectification circuit 7.The primary around Group N1 and secondary windings N2 passes through the magnetic coupling of transformer 6.Full-bridge circuit 2 is by first, second switch element S1, S2 is connected in series First switch branch 3 and the composition of second switch branch 4 that is connected in series by the 3rd, by the 4th switch element S3, S4.

Anti-parallel diodes DS1~DS4 is connected in switch element S1~S4.Herein, opened as these Close element and in the case of having used MOSFET (mos field effect transistor), as the pole of reverse parallel connection two Pipe, using MOSFET body diode.In addition, switch element S1~S4 has parasitic capacitance CS1~CS4.Now, as electric capacity Device, buffer condenser can also be connected in parallel with switch element S1~S4.In Fig. 1, as an example, by switch element S1, S2 are arranged to MOSFET, and switch element S3, S4 are arranged to IGBT (insulated gate bipolar transistor).In the friendship of full-bridge circuit 2 Reactor Lr is inserted in series connection between armature winding N1 between stream terminal.Herein, for reactor Lr, transformer can also be utilized 6 leakage inductance.

Rectification circuit 7 is made up of 2 smooth reactor L1, L2 and 2 diodes D1, D2.Connect in secondary windings N2 one end Smooth reactor L1 one end and diode D2 negative electrode are connected to, is connected with smooth reactor L2's in the secondary windings N2 other end One end and diode D1 negative electrode.Smooth reactor L1, L2 other end are connected with smoothing capacity device C2 one end, diode D1, D2 anode are connected with the smoothing capacity device C2 other end.Herein, can also use switch element replace diode D1, D2.In this case, by using synchronous rectification mode, it can further improve the efficiency of DC-DC converter 1.

The present invention DC-DC converter 1 feature be according to load R1 amount of electric power supply, changeable switch element Operator scheme.Illustrated using switchings of the Fig. 2 to operator scheme.

Fig. 2 is the figure for the switching for illustrating operator scheme.Power output Pout is the output electricity detected by current sensor 8 The product of stream and the output voltage detected by voltage sensor 9.Pth is the setting set for switching operation modes.It is defeated In the case of going out power P out more than setting Pth, control unit 5 is heavy duty pattern M1 as first mode, and driving is opened Close element S1~S4.Now when by phase-shifted manner driving switch element S1~S4, ZVT can be carried out.Exporting When power P out is below setting Pth, the light load mode M2 as second mode is transferred to.Control unit 5 makes switch first Part S3, S4 stop in the off state, only driving switch element S1, S2.Control unit 5 is driven by controlling switch element S1, S2 Dynamic frequency, control power output.In addition, in the figure, the bottom in figure records driving switch element S1~S4 driving Signal, high-side represent ON signals, and low level side represents OFF signal.

Fig. 3 is the figure for the determining method for illustrating setting Pth.Ploss-Pout straight lines shown by dashed lines are represented in heavy burden The loss in each power output Pout when making its action under load pattern M1, represented by the Ploss-Pout straight lines shown in solid line The loss in each power output Pout when making its action under light load mode M2.So, according to according to power output Pout's Size loses the mode of small operator schemes M1, M2 of Ploss to determine setting Pth.In theory by dotted line and reality The intersection point of line can turn into the best situation of efficiency as Pth.Certainly, it is specified that value Pth can also arbitrarily be set.

Herein, when power output Pout and setting Pth is with degree size, exist in heavy duty pattern M1 and light load The situation of frequent switching between pattern M2.In this case, as shown in figure 4, existing by determining respectively from heavy duty pattern M1 is transformed into light load mode M2 setting Pth1 and heavy duty pattern M1 setting is transformed into from light load mode M2 Pth2 and situation about can solve the problem that.Setting Pth1 and Pth2 difference take into account efficiency and switching frequency by the product for being applicable this technology To select decision.

Then, the circuit operation under the light load mode M2 of DC-DC converter 1 is illustrated using Fig. 5 to Figure 13. Heavy duty pattern M1 circuit operation is because conventional phase-shifted manner can be applicable omitting the description.Fig. 5 is to illustrate to become in DC-DC Voltage, the current waveform figure of action under the light load mode M2 of parallel operation 1.Illustrate the voltage waveform in Fig. 5 first.S1 drive signals The drive signal waveform that control unit 5 exports to switch element S1~S4 is shown respectively in~S4 drive signals.In the figure, switch Element S1~S4 is set to ON (unlatching) when the drive signal waveform exported to switch element S1~S4 becomes high level, The drive signal waveform exported to switch element S1~S4 is set to OFF (shut-off) when turning into low level.T1 voltages represent primary The voltage waveform of the node T1 of winding N1 side voltage, T2 voltages represent the node T2 of armature winding N1 another side Voltage voltage waveform, between T1-T2 voltage represent from T1 voltages subtracted T2 voltages after voltage waveform.Then, in Fig. 5 Current waveform illustrate.S1 electric currents, S2 electric currents represent electric current between switch element S1, S2 Drain-Source respectively.CS1 electricity Stream~CS4 electric currents represent to flow through parasitic capacitance CS1~CS4 current waveform respectively.For CS1 electric currents~CS4 electric currents, respective In parasitic capacitance CS1~CS4, by from one end of the parasitic capacitance of the drain electrode connection with switch element to the source electrode with switch element The direction of the other end flowing of the parasitic capacitance of connection is set to just, and positive current is referred to as into charging current, and negative current is referred to as putting Electric current.DS1 electric currents~DS4 electric currents represent to flow through anti-parallel diodes DS1~DS4 current waveform respectively.For DS1 electricity Stream~DS4 electric currents, in each anti-parallel diodes DS1~DS4, it will be set to just from anode to the direction of cathode flow.Separately Outside, during being divided in Figure 5 by each dotted line (a)~(h) respectively with (pattern a)~(pattern h) is corresponding described below. Under light load mode M2, by (pattern a)~(patterns whole pattern h), switch element S3, S4 drive signal turn into disconnected Open.

(pattern a)

Fig. 6 is to illustrate the action (pattern a) circuit diagram under the light load mode M2 of (a) during Fig. 5 is shown.Open Switch element S1.Switch element S1 both end voltage is turned on by anti-parallel diodes DS1 to turn into no-voltage, switch element S1 turns into ZVT.Hereafter, when flowing through reactor Lr electric current and reaching zero, conduct is flowed through in anti-parallel diodes DS4 The reverse recovery current of electric current before Reverse recovery, the electric current for flowing through reactor Lr increase along positive direction.Hereafter, reversely simultaneously During di- pole pipe DS4 Reverse recoveries, parasitic capacitance CS4 charging current and parasitic capacitance are turned into by switch element S1 electric current CS3 discharge current.

(pattern b)

Fig. 7 is to illustrate the action (pattern b) circuit diagram under the light load mode M2 of (b) during Fig. 5 is shown.Pass through Parasitic capacitance CS3 is discharged, and anti-parallel diodes DS3 both end voltage is reduced, the anti-parallel diodes when intersecting no-voltage DS3 is turned on.When anti-parallel diodes DS3 is turned on, parasitic capacitance CS3 discharge current and parasitic capacitance CS4 charging electricity Rheology, which obtains, not to be flowed.The electric current for flowing through anti-parallel diodes DS3 is returned by switch element S1 and reactor Lr, armature winding N1 Return to anti-parallel diodes DS3.Flowing through the electric current in the path gradually increases.

(pattern c)

Fig. 8 is to illustrate the action (pattern c) circuit diagram under the light load mode M2 of (c) during Fig. 5 is shown.Shut-off Switch element S1.Flowing through anti-parallel diodes DS3 electric current turns into parasitic capacitance CS1 charging current and parasitic capacitance CS2 discharge current.By parasitic capacitance CS2 electric discharge, node T1 voltage is reduced, but node T2 voltages are due to reverse parallel connection Diode DS3 is turned on and is maintained the voltage higher than DC voltage V1.Thus, the voltage between node T1- nodes T2 is to losing side To expansion.

(pattern d)

Fig. 9 is to illustrate the action (pattern d) circuit diagram under the light load mode M2 of (d) during Fig. 5 is shown.Pass through Parasitic capacitance CS2 electric discharge, anti-parallel diodes DS2 both end voltages are reduced, when intersecting no-voltage, anti-parallel diodes DS3 is turned on.When anti-parallel diodes DS2 is turned on, parasitic capacitance CS2 discharge current and parasitic capacitance CS1 charging electricity Rheology, which obtains, not to be flowed.Anti-parallel diodes DS2 electric current is flowed through by reactor Lr, armature winding N1, and by reversely simultaneously Di- pole pipe CS3 returns to anti-parallel diodes CS2.The electric current for flowing through the path gradually decreases.

(pattern e)

Figure 10 is to illustrate the action (pattern e) circuit diagram under the light load mode M2 of (e) during Fig. 5 is shown.Open Open switch element S2.Switch element S2 both end voltage turns into no-voltage because anti-parallel diodes DS2 is turned on, switch member Part S2 turns into ZVT.Hereafter, when flowing through reactor Lr electric current and reaching zero, work is flowed through in anti-parallel diodes DS3 For the reverse recovery current untill Reverse recovery, the electric current for flowing through reactor Lr increases in negative direction.Hereafter, reversely simultaneously During di- pole pipe DS3 Reverse recoveries, parasitic capacitance CS3 charging current and parasitic capacitance are turned into by switch element S2 electric current CS4 discharge current.Node T2 voltages are reduced by parasitic capacitance CS4 electric discharge, but node T1 voltage is due to switch member Part S2 is turned on and is maintained no-voltage.Thus, the voltage between node T1- nodes T2 is close to zero.

(pattern f)

Figure 11 is to illustrate the action (pattern f) circuit diagram under the light load mode M2 of (f) during Fig. 5 is shown.It is logical Superparasitization electric capacity CS4 electric discharge, anti-parallel diodes DS4 both end voltages are reduced, when intersecting no-voltage, the pole of reverse parallel connection two Pipe DS4 is turned on.When anti-parallel diodes DS4 is turned on, the charging of parasitic capacitance CS4 discharge current and parasitic capacitance CS3 Electric current becomes not flow.Anti-parallel diodes DS4 electric current is flowed through by armature winding N1, reactor Lr, and passes through switch Element S2 returns to anti-parallel diodes DS4.Flowing through the electric current in the path gradually increases.

(pattern g)

Figure 12 is to illustrate the action (pattern g) circuit diagram under the light load mode M2 of (g) during Fig. 5 is shown.Close Disconnected switch element S2.Switch element S2 electric current is flowed through as the charging of parasitic capacitance CS1 discharge current and parasitic capacitance CS2 Electric current.Node T1 voltage is risen by parasitic capacitance CS2 charging, but node T2 voltage is due to anti-parallel diodes D4 is turned on and is maintained no-voltage.Thus, the voltage between node T1- nodes T2 ramps up to pros.

(pattern h)

Figure 13 is to illustrate the action (pattern h) circuit diagram under the light load mode M2 of (h) during Fig. 5 is shown.It is logical Superparasitization electric capacity CS1 electric discharge, anti-parallel diodes DS1 both end voltages are reduced, when intersecting no-voltage, the two of reverse parallel connection Pole pipe DS1 is turned on.When anti-parallel diodes DS1 is turned on, parasitic capacitance CS1 discharge current and filling for parasitic capacitance CS2 Electric current becomes not flow.The electric current for flowing through anti-parallel diodes DS1 passes through anti-parallel diodes DS4 and armature winding N1, reactor Lr, return to anti-parallel diodes DS1.The electric current for flowing through the path gradually decreases.

After, return to and (pattern a), above-mentioned (pattern a)~(pattern h) action is repeated.

In addition, (pattern a)~(pattern for the electric current adverse current for flowing through smooth reactor L1, L2 in pattern h) be present, but it is logical The value and change winding N1, N2 turn ratio for crossing increase reactor can avoid.

Why power output can be controlled by controlling switch element S1, S2 driving frequency, be because making in node T1- The time that voltage is produced between node T2 is changed.That is, when improving driving frequency, the node T1- nodes in every 1 cycle The virtual value increase of voltage between T2, and power output can be improved.The power output if driving frequency is reduced in turn Decline.Increase power output to not improve driving frequency, if to switch element S3, S4 using the big switch of parasitic capacitance Element, then it can make to produce the time delay of voltage at transformer both ends.Connect alternatively, it is also possible in parallel with switch element S3, S4 Connect buffer condenser.Because (pattern a), (the discharge and recharge time of buffer condenser is being added in pattern e), so in node Show the time lengthening of voltage between T1- nodes T2 and caused by.The another of power output is improved as driving frequency is not improved Outer method, can also be to anti-parallel diodes DS3, DS4 using the slow diode of reverse recovery characteristic.(pattern d), (in pattern h), the voltage between node T1- nodes T2 is maintained, until anti-parallel diodes DS3, DS4 Reverse recovery terminate Untill.Therefore power output can be improved.

As switch element S1, S2, can be improved sometimes through using the fast switch element of switching characteristic, efficiency.Usually, Quickly, switching losses are small for MOSFET switching characteristic.In addition, IGBT conducting resistance very little, conduction losses are small.For example, conduct Switch element S1, S2, using MOSFET, for switch element S3, S4, use IGBT.Thus, can suppress in heavy duty pattern M1 Under conduction losses, can also reduce the switching losses under light load mode M2.

In turn, IGBT is used to switch element S1, S2, when using MOSFET to switch element S3, S4, output can be improved Power.Usually, MOSFET body diode reverse recovery characteristics are slow.If anti-parallel diodes DS3, DS4 are utilized MOSFET body diode, then (pattern e), (in pattern a), the voltage between node T1- nodes T2 is being maintained, until reversely simultaneously The Reverse recovery of di- pole pipe DS3, DS4 is terminated.Therefore, power output can be improved.In addition, even in switch element S1, S2 have used MOSFET, in the case of having used IGBT to switch element S3, S4, as shown in figure 14, if making switch element S1, S2 stop in the off state, only driving switch element S3, S4, it is understood that can obtain with making to switch element S1, S2 With IGBT, the same effect of the DC-DC converter of MOSFET composition is used to switch element S3, S4.In addition, in turn, i.e., Make using IGBT to switch element S1, S2, in the case of using MOSFET to switch element S3, S4, as shown in figure 14, if Switch element S1, S2 is set to stop in the off state, only driving switch element S3, S4, it is understood that available and first to switch Part S1, S2 use MOSFET, and the same effect of the DC-DC converter of IGBT structure is used to switch element S3, S4.

It is characterised by according to above-mentioned, of the invention DC-DC converter 1：Zero electricity is also easily realized when light load Compress switch.But when the amount of electric power supply to load can be considered as generally equal with zero, exist and cannot ensure parasitic capacitance The electric current that CS1~CS4 discharge and recharge needs, switch element S1, S2 turn into the situation of hard switching.But now, switch element Driving frequency when S1, S2 driving frequency proportion load model M1 is low.Therefore, even if can be considered as to the amount of electric power supply of load When generally equal with zero such, also proportion load model M1 efficiency highs, the present invention can be described as effectively light load mode M2.

It is the circuit of the mode of resonance differed with the operating principle of phase-shifted manner in addition, in foregoing patent document 2. Therefore, in the circuit of mode of resonance in order that resonance operating stably must limited frequency range, except to input voltage range, defeated Go out voltage variable range limitation it is more, the circuit of mode of resonance is FREQUENCY CONTROL, needed to reduce output area with it is humorous Vibration frequency separates, but increase due to fluctuation or needs electric power for driving element, it is difficult to efficient.

On the other hand, in the circuit of phase-shifted manner, in addition to the on-off of switch element, also utilize and these switches The conducting of diode and the discharge and recharge to parasitic capacitance of element in parallel connection act.Also, in order to improve efficiency, such as Where switch element carries out realizing that ZVT or the switch close to it are important during on-off.Therefore, control to parasitic electricity The discharge and recharge of appearance is important.

In the past, in the light load that load lightens, because being flowed through without sufficient electric current in circuit, what is switched is defeated Go out electric capacity can not fully discharge and recharge and turn into hard switching, cause degradation in efficiency.But in the present embodiment, by gently bearing The action for the switch branch that one group of switch element making full-bridge circuit in load pattern, being connected in series is formed stops, so as to disappear Except this point.Confirm the state of electric current flowed in circuit in such a state, reason or inexplicit, but with Past control is compared, it is thus identified that is increased in light load for carrying out the electric current of discharge and recharge to the output capacitance of switch.Thus, i.e., Make, in the light load that load has lightened, also to promote the discharge and recharge of the output capacitance of switch, Sofe Switch can be turned into.

I.e. according to the present embodiment, switched compared with former control method, can be opened with low-voltage, switching losses subtract It is few.In addition, according to the present embodiment, compared with conventional control method, because frequency is low being easier to reduce output area, separately Stopped outside by the action of be connected in series one group of switch element of the switch branch for making the side of composition one, the driving loss of these switches It is also controlled by, can further realizes the raising of efficiency.

【Embodiment 2】

Figure 15 is the circuit structure diagram of the DC-DC converter 101 of embodiments of the invention 2.Pair with Fig. 1 identicals part assign Same-sign is given, and the description thereof will be omitted.Rectification circuit 7 is made up of smooth reactor L11 and 2 diodes D1, D2.Smooth reactance Device L11 one end is connected with diode D1, D2 negative electrode, the smooth reactor L11 other end and smoothing capacity device C2 one end Connection.2 secondary windings N21, N22 one end interconnect, and its tie point is connected to the smoothing capacity device C2 other end.It is secondary Level winding N21, N22 other end are respectively the anode that N21 is connected to diode D1, and N22 is connected to diode D2 anode. Thus, compared with embodiment 1, because smooth reactor can be cut down, component number of packages can be cut down, and cost can be reduced.Separately Outside, diode D1, D2 are replaced by using switch element, and high efficiency can be further realized using synchronous rectification mode.

【Embodiment 3】

Figure 16 is the circuit structure diagram of the DC-DC converter 102 of embodiments of the invention 3.Pair with Fig. 1 identicals part assign Same-sign is given, and the description thereof will be omitted.Rectification circuit 7 is by smooth reactor L12, two poles for being connected in series diode D1, D2 Pipe branch 10, the diode branch 11 that diode D3, D4 connect and are connected in parallel with diode branch 10 are formed.Smooth reactor L12 one end is connected with one end of diode branch 10, and the smooth reactor L12 other end is connected with smoothing capacity device C2 one end, The other end of diode branch 10 is connected with the smoothing capacity device C2 other end.Diode D1, D2 tie point and diode D3, D4 Tie point be connected with secondary windings N2 both ends.Thus, inverse pressure-resistant small diode can be used.Such structure is adapted to use In the big situation of output voltage.In addition, diode D1~D4 is replaced by using switch element, and can using synchronous rectification mode Further realize high efficiency.

【Embodiment 4】

Figure 17 is the sketch structure figure of the power-supply system of conventional electric automobile 31.Charger 32 passes through AC-DC converter Alternating electromotive force from AC power 51 is transformed to direct current power by 52, and direct current power transformation is electric power storage by DC-DC converter 53 Required voltage charge to provide electric power in pond 41.On the other hand, DC-DC converter 55 is to low as the voltage than battery 41 The voltage of the battery 42 of voltage carries out transformation and to loading 56 supply electric powers.To load 56 amount of electric power supply more than situation Under, the electric power of battery 41 is supplied to DC-DC converter 55 and battery 42 by DC-DC converter 54.But from exchange In the case that situation that power supply 51 charges to charging accumulator 41 etc. is lacked to the amount of electric power supply of load 56, DC-DC conversion be present The problem of power converter efficiency of device 54 declines.Therefore, charger 32 has DC-DC converter 57, will come from AC-DC converter 52 electric power does not supply electricity from DC-DC converter 57 by DC-DC converter 54 to DC-DC converter 55 and battery 42 Power.

Figure 18 is the power-supply system of the electric automobile 131 for the DC-DC converter 1 for employing according to an embodiment of the invention 4 Sketch structure figure.Pair same-sign is assigned with Figure 17 identicals part, and the description thereof will be omitted.By using in foregoing implementation The DC-DC converter 1 that example 1 illustrates replaces the DC-DC converter 54 in Figure 17, even if so as to the amount of electric power supply to load 56 In the case of few, DC-DC converter 1 also being capable of high efficiency supply electric power.Thus, charger 132 need not be in Figure 17 DC-DC Converter 57, device number of packages can be cut down, significantly cost of implementation can reduced, and power supply can be carried out with high efficiency.

In automobile 131, when being charged from AC power 51 by charger 132 to battery 41, DC-DC converter 1 The situation of step-down is more compared with driving frequency of switch element S1, S2 driving frequency when heavy duty pattern M1.That is, it is at night Between wait car in itself when not in use between the state that is charged to battery 41.When such, the bottom line that necessitates it is non- Often small load 56.Therefore, when the amount of electric power supply to load can be considered as essentially equal to zero, light load mode M2 Proportion load model M1 efficiency highs, it may be said that on electric automobile utilize this example demonstrates DC-DC converter right and wrong It is often effective.In addition, carried out in the present embodiment with the example of the DC-DC converter that Application Example 1 illustrates in automobile 131 Illustrate, it is still, similarly effective even in the DC-DC converter that the application of automobile 131 is illustrated by embodiment 2 and embodiment 3.

Label declaration

1st, 53~55,57,101,102 DC-DC converter

2 full-bridge circuits

3rd, 4 switch branch

5 control units

6 transformers

7 rectification circuits

8 current sensors

9 voltage sensors

10th, 11 diode branch

31 electric automobiles

32 chargers

41st, 42 battery

51 AC powers

52 AC-DC converters

56th, R1 is loaded

131 electric automobiles

132 chargers

V1 dc sources

C1, C2 smoothing capacity device

The smooth reactor of L1, L2, L11, L12

Lr reactors

N1, N2 winding

S1~S4 switch elements

DS1~DS4 anti-parallel diodes

CS1~CS4 parasitic capacitances

M1 heavy duty patterns

M2 light load modes

Pout power outputs

Pth, Pth1, Pth2 setting

D1~D4 diodes

T1, T2 node

Claims (11)

1. A kind of 1. DC-DC converter, it is characterised in that：

   Possess：On-off circuit, the on-off circuit possess switch and the diode being connected with the switch in parallel,

   The electric power output that the on-off circuit will enter between DC terminal between ac terminal,

   Wherein, using the reverse recovery characteristic of electric current reverse flow in the diode, by electric power output to the exchange end Between son,

   The DC-DC converter possesses：

   The 1st switch branch that 1st, the 2nd switch is connected in series；

   By the 2nd switch branch that the 3rd, the 4th switch is connected in series and is connected in parallel with the described 1st switch branch；And

   Between DC terminal being set between the both ends of the 2nd switch branch between the both ends of described 1st switch branch, and by the described 1st, 2nd switch be connected in series a little and the described 3rd, the 4th switch be connected in series a little between be set to full-bridge circuit between ac terminal,

   Wherein, the DC-DC converter possesses with the described 1st, the 2nd, the 3rd, the 4th switch in parallel are connected diode and constitute The on-off circuit,

   The DC-DC converter possesses：

   The control unit of the full-bridge circuit is controlled,

   When amount of electric power supply between the DC terminal is more than set-point, described control unit, which performs, makes the described 1st, the 2nd, 3rd, the 1st pattern of the 4th switch element driving,

   When amount of electric power supply between the DC terminal is below the set-point, described control unit, which performs, to be made described in composition One group of switch element of the switch branch of the side of the 1st switch branch or the 2nd switch branch is so that off-state stops and makes composition described the 2nd pattern of one group of switch element driving of the switch branch of the opposite side of 1 switch branch or the 2nd switch branch,

   Diode possessed by one group of switch element of the switch branch for the side being stopped when performing 2 pattern, Compared with diode possessed by one group of switch element of the switch branch of the side driven when performing 2 pattern Reverse recovery characteristic is slower,

   The DC-DC converter possesses：

   Possess the armature winding being connected between the ac terminal and the change with the magnetic-coupled secondary windings of the armature winding Depressor,

   In the 2nd pattern, electric current the diode being connected in parallel with the switch element being stopped flowing forward, it Afterwards, the switch element being stopped remains off constant, in the diode that the switch element being stopped with this is connected in parallel It is counter flow upwardly through reverse recovery current, the reverse recovery current is stopped from the positive pole of the DC terminal via with this Diode and the armature winding that switch element is connected in parallel flow to the negative pole of the DC terminal.
2. 2. DC-DC converter as claimed in claim 1, it is characterised in that

   The diode is anti-parallel diodes.
3. 3. DC-DC converter as claimed in claim 1, it is characterised in that

   Possess：

   With the rectification circuit that smooth smooth reactor is carried out to the electric power from the transformer；And

   The DC terminal being connected with the rectification circuit.
4. 4. DC-DC converter as claimed in claim 3, it is characterised in that

   2nd pattern increases power output by improving switching frequency.
5. 5. DC-DC converter as claimed in claim 4, it is characterised in that

   Switch element is arranged to the switch,

   Described control unit when performing 1 pattern in a phase shifted manner come drive the described 1st, the 2nd, the 3rd, the 4th switch member Part, when performing 2 pattern, with frequency control system come one group of switch of the switch branch for the side to be driven Element.
6. 6. DC-DC converter as claimed in claim 4, it is characterised in that

   With the described 1st, the 2nd, the 3rd, capacitor is set to the 4th switch in parallel,

   Switch element is arranged to the described 1st, the 2nd, the 3rd, the 4th switch,

   One group of switch element of the switch branch for the side being stopped when performing 2 pattern possesses the capacitor, The electricity possessed by one group of switch element of the switch branch of capacity ratio side to be driven when performing 2 pattern Container is big.
7. 7. DC-DC converter as claimed in claim 4, it is characterised in that

   Switch element is arranged to the switch,

   The side being stopped when performing 2 pattern the switch branch one group of switch element respectively with buffer condenser It is connected in parallel.
8. 8. DC-DC converter as claimed in claim 4, it is characterised in that

   Switch element is arranged to the switch,

   When performing 2 pattern, the switching characteristic ratio of one group of switch element of the switch branch for the side to be driven is being held One group of switch element of the switch branch for the side being stopped during row 2 pattern is fast.
9. 9. DC-DC converter as claimed in claim 4, it is characterised in that

   Switch element is arranged to the switch,

   When performing 2 pattern, one group of switch element of the switch branch for the side to be driven is set to MOSFET, and One group of switch element for performing the switch branch for the side being stopped during 2 pattern is set to IGBT.
10. 10. DC-DC converter as claimed in claim 4, it is characterised in that

    Switch element is arranged to the switch,

    When performing 2 pattern, one group of switch element of the switch branch for the side to be driven is set to IGBT, and is holding One group of switch element of the switch branch for the side being stopped during row 2 pattern is set to MOSFET.
11. 11. DC-DC converter as claimed in claim 4, it is characterised in that

    MOSFET element is arranged to the switch,

    The diode is the body diode of MOSFET element.