CN106160447A - A kind of Dead Time optimal control method being applicable to SiC base brachium pontis power circuit - Google Patents

Abstract

The invention discloses a kind of Dead Time optimal control method being applicable to SiC base brachium pontis power circuit, Integrated comparative grid voltage drops to the time of threshold voltage, channel current fall time, drain-source voltage rise time and presets maximum Dead Time；Grid voltage drops to the time of threshold voltage can be according to raster data model equivalent circuit calculating gained；Channel current is chosen under off-line state fall time, the channel current fall time under heavy duty, hot conditions；Using the upper, lower tube auxiliary circuit gate source voltage trailing edge by marginal detector switch tube and drain-source voltage trailing edge to detect, the difference between the two is the drain-source voltage rise time.By comparing these time, the optimum Dead Time of output, through above-mentioned optimum Dead Time after the cut-off signals output of switching tube, be corresponding switching tube opens signal output time.The present invention, on the premise of ensureing system functional reliability, effectively reduces the power attenuation that Dead Time causes, improves changer work efficiency.

Description

A kind of Dead Time optimal control method being applicable to SiC base brachium pontis power circuit

Technical field

The present invention relates to a kind of Dead Time optimal control method being applicable to SiC base brachium pontis power circuit, belong to brachium pontis Time Control Technique field, circuit dead band.

Background technology

In the design of bridge arm circuit, in order to avoid upper, lower tube simultaneously turns on, bridge arm direct pass phenomenon occurs, need at PWM Control signal arranges Dead Time, but when dead band time setting is too short, upper, lower tube easily occurs to lead directly to cause excessive merit Consumption or even fault；And when dead band time setting is long, can drop because of fly-wheel diode ON time long increase circuit loss again Inefficient.Therefore, for voltage source type converter, the setting of Dead Time has much relations with whole aircraft reliability and efficiency. It addition, the length of Dead Time also can produce impact to the output voltage quality of power inverter.

For SiC base voltage source code converter, owing to SiC device switching speed is fast, Dead Time sets changer Can affect the most prominent.First, Dead Time is relevant with the switch time of device, and the switch time of SiC device and load Size has relatively Important Relations.Traditional method to set up of Dead Time is by measuring switching device under heavy duty, high temperature operating conditions Turn-off time, Dead Time is set on this basis, if SiC base voltage source code converter is still adopted in this way, can lead The lethal zone time is excessive, it is impossible to gives full play to the performance advantage that SiC device is brought to changer, and can cause fly-wheel diode Loss increase.Visible, the Reasonable adjustment of Dead Time is extremely important for SiC base voltage code converter.

Summary of the invention

The technical problem to be solved is: provide a kind of Dead Time being applicable to SiC base brachium pontis power circuit Optimal control method, the setting to voltage source type converter brachium pontis breaker in middle device Dead Time is optimized adjustment, is ensureing On the premise of system reliability, reduce the power attenuation brought by Dead Time, improve the work efficiency of changer.

The present invention solves above-mentioned technical problem by the following technical solutions:

A kind of Dead Time optimal control method being applicable to SiC base brachium pontis power circuit, this optimal control method will be real Time the switching tube drain-source voltage rise time t that obtains of on-line measurement_vr, calculated grid voltage drop to threshold voltage time Between t_gs, channel current t fall time that obtains of off-line measurement_cf, preset maximum Dead Time t_dt(max)Input microcontroller together In device, above-mentioned four kinds of times are compared by microcontroller according to the following formula that compares, and export optimum Dead Time t_dt(opt)； The described formula that compares is:

$t_{dt\left(opt\right)}=min\left(max\right(t_{cf(I_{L\left(max\right)},T_{j\left(max\right)})},t_{vr},t_{gs}),t_{dt\left(max\right)}),$

Wherein,When representing load maximum, junction temperature high workload condition, the channel current that off-line measurement obtains Fall time.

As a preferred embodiment of the present invention, described switching tube drain-source voltage rise time t_vrMeasuring method be:

In upper pipe circuit add gate source voltage testing circuit H, drain-source voltage testing circuit H, marginal detector H, on manage Auxiliary adjustment circuit, upper pipe signal isolation circuit；Gate source voltage testing circuit L, drain-source voltage detection is added in down tube circuit Circuit L, marginal detector L, down tube auxiliary adjustment circuit, down tube signal isolation circuit；In whole SiC base brachium pontis power circuit Add signal isolation circuit；

When upper pipe turns off, marginal detector H is electric with the upper pipe grid source of certain frequency detection by gate source voltage testing circuit H Pressure, when upper pipe gate source voltage declines, marginal detector H output pulse signal s_H1, send into upper pipe auxiliary through signal isolation circuit Regulation circuit, upper pipe auxiliary adjustment circuit output feedback signal s_H(aux), feed back to marginal detector through upper pipe signal isolation circuit H, meanwhile, upper pipe auxiliary adjustment circuit output upper tube gate source voltage trailing edge t_H(aux)；In like manner, down tube auxiliary adjustment circuit passes through Drain-source voltage testing circuit L detects down tube gate source voltage trailing edge t_L(aux), t_H(aux)And t_L(aux)Difference be t_vr；

When down tube turns off, marginal detector L is electric with certain frequency detection down tube grid source by gate source voltage testing circuit L Pressure, when down tube gate source voltage declines, marginal detector L output pulse signal s_L1, send into down tube auxiliary through signal isolation circuit Regulation circuit, down tube auxiliary adjustment circuit output feedback signal s_L(aux), feed back to marginal detector through down tube signal isolation circuit L, meanwhile, down tube auxiliary adjustment circuit output lower tube gate source voltage trailing edge t_L(aux)；In like manner, upper pipe auxiliary adjustment circuit passes through Pipe drain-source voltage trailing edge t in drain-source voltage testing circuit H detection_H(aux), t_L(aux)And t_H(aux)Difference be t_vr。

As a preferred embodiment of the present invention, described grid voltage drops to the time t of threshold voltage_gsComputational methods For: can be calculated according to raster data model equivalent circuit, described raster data model equivalent circuit is by gate driver circuit equivalent resistance, grid The input capacitance of polar circuit equivalent inductance, source electrode common mode inductance and switching tube is in series.

As a preferred embodiment of the present invention, described grid voltage drops to the time t of threshold voltage_gsBy following second order Circuit equation is tried to achieve:

${\mathrm{LC}}_{iss}\frac{d^2{u}_{GS}}{{{\mathrm{dt}}_{gs}}^2}+R_G{C}_{iss}\frac{{\mathrm{du}}_{GS}}{{\mathrm{dt}}_{gs}}+u_{GS}=0,$

Wherein, L is grid circuit equivalent inductance and source electrode common mode inductance sum, C_issFor the input capacitance of switching tube, u_GSFor Grid voltage, R_GFor gate driver circuit equivalent resistance.

As a preferred embodiment of the present invention, channel current t fall time that described off-line measurement obtains_cfFor: off-line Under state, the channel current fall time that measurement obtains when load maximum, junction temperature high workload condition.

The present invention uses above technical scheme compared with prior art, has following technical effect that

1, the present invention is applicable to the Dead Time optimal control method of SiC base brachium pontis power circuit, can be according to load feelings Condition adjusts the Dead Time of control signal, on the basis of the reliability ensureing system work, when can be effectively reduced by dead band Between the loss that brings, improve the work efficiency of changer.

2, the present invention is applicable to the Dead Time optimal control method of SiC base brachium pontis power circuit, it is possible to give full play to SiC The performance advantage of device, improves complete machine work efficiency.

Accompanying drawing explanation

Fig. 1 is bridge arm type structural circuit schematic diagram.

Fig. 2 is the exemplary control signal schematic diagram of bridge arm structure circuit.

Fig. 3 is gate driver circuit schematic equivalent circuit.

Fig. 4 is drain-source voltage rise time t_vrSchematic diagram is affected with load change.

Fig. 5 is the circuit block diagram of Dead Time optimal control method of the present invention.

Fig. 6 is drain-source voltage rise time t_vrMeasuring principle waveform diagram.

Fig. 7 is the circuit theory diagrams of Dead Time optimal control method of the present invention.

Detailed description of the invention

Embodiments of the present invention are described below in detail, and the example of described embodiment is shown in the drawings.Below by The embodiment being described with reference to the drawings is exemplary, is only used for explaining the present invention, and is not construed as limiting the claims.

The present invention proposes a kind of Dead Time optimal control method being applicable to SiC base brachium pontis power circuit, by reality Time detection switching tube duty, can according to loading condition adjust control signal Dead Time, ensure system work Reliability on the basis of, be effectively reduced the loss brought by redundancy Dead Time, improve the work efficiency of changer.

As shown in Figure 2, in the control signal of bridge arm circuit, a switch periods needs arrange two sections of Dead Times, Be respectively as follows: (1) upper pipe to turn off, down tube open before Dead Time (t₁～t₂)；(2) down tube turn off, upper pipe open before dead District time (t₃～t₄)。

In typical bridge arm structure is applied, during the conducting of upper pipe, load current, by power supply, flows into through upper pipe, brachium pontis midpoint Load end.When upper pipe turns off, at Dead Time (t₁～t₂In), load current can the change of current extremely afterflow two pole antiparallel with down tube Guan Zhong, now the voltage at brachium pontis midpoint can be undergone mutation, and upper pipe drain-source voltage also can be undergone mutation.During down tube conducting, load electricity Flow by load end, flow into earth point through brachium pontis midpoint, down tube.When down tube turns off, at Dead Time (t₃～t₄In), load electricity In the fly-wheel diode that the stream supreme pipe of the change of current is in parallel, the voltage at brachium pontis midpoint can be undergone mutation, and down tube drain-source voltage is also dashed forward Become.

Being analyzed from above, in typical bridge arm structure is applied, when upper, lower tube turns off, drain-source voltage all can suddenly change, The two Dead Time adjusted & optimized strategy is identical.When switching tube turns off, switching tube gate source voltage drops to the time of threshold voltage t_gsNot only relevant with raster data model loop parameter, also with the time t of loop of power circuit breaker in middle pipe trench road current reduction to zero_cf With drain-source voltage rise time t_vrRelevant.

In the present invention, switching tube grid voltage drops to the time t of threshold voltage_gsCan be by equivalence as shown in Figure 3 Circuit calculates；As shown in Figure 4, switching tube channel current t fall time_cfLittle by load effect, heavy duty, high temperature work can be taken Make the measurement result under state；Switching tube drain-source voltage rise time t_vrAffected by a load bigger, need online survey in real time Amount；During in order to prevent from loading too small, measure the t of gained_vrBig especially, need to preset maximum Dead Time t_dt(max).These times Will be in input microcontroller, microcontroller exports optimum Dead Time by following formula:

$t_{dt\left(opt\right)}=min\left(max\right(t_{cf(I_{L\left(max\right)},T_{j\left(max\right)})},t_{vr},t_{gs}),t_{dt\left(max\right)})---\left(1\right)$

Specifically comprising the following steps that of this dead band time-optimized adjustment control method

In circuit shown in Fig. 1, upper pipe illustrates as a example by turning off, be to SiC base voltage code converter bridge arm power electricity Road Dead Time is optimized, it is to be appreciated that upper pipe gate source voltage t fall time_gs, channel current t fall time_cf, drain-source electricity Pressure rise time t_vr.Fig. 5 gives Dead Time of the present invention and optimizes circuit block diagram.

Concrete grammar is as follows:

(1) upper pipe gate source voltage t fall time_gsCan be calculated by equivalent circuit as shown in Figure 3 and obtain, once it drives Circuit parameter determines, its gate source voltage t fall time_gsI.e. can determine that.

(2) due to device channel downslope time t_cfIt is difficult to measure, but it is less by load effect, therefore t_cfCan Take load maximum, channel current t fall time under the conditions of junction temperature high workload_cf, can be obtained by off-line measurement in advance.

(3) upper pipe drain-source voltage rise time t_vrRelevant with load, need to measure in real time.Fig. 6 gives t_vrMeasure Principle waveform diagram, in order to determine t_vr, needs are two auxiliary circuits of addition in bridge arm circuit: a. gate source voltage testing circuit (GVTD)；B. drain-source voltage testing circuit (DVFD).Fig. 7 gives Dead Time optimal control circuit theory diagrams, and GVTD is upper Pipe gate source voltage change detecting circuit, DVFD be down tube drain-source voltage testing circuit (when down tube drain-source voltage drops to zero, upper pipe Drain-source voltage i.e. rises to supply voltage).As it is shown in fig. 7, marginal detector H detects upper pipe grid source by GVTD with certain frequency Voltage, when upper pipe gate source voltage declines, marginal detector H exports s_H1, send into microcontroller, microcontroller through signal isolation circuit Upper pipe auxiliary adjustment circuit output feedback signal s in device_H(aux), feed back to marginal detector through upper pipe signal isolation circuit, improve Detection frequency, prevents error detection.Now, upper pipe auxiliary adjustment circuit output t_H(aux).Similar, down tube auxiliary adjustment circuit leads to Cross DVFD and detect down tube drain-source voltage trailing edge, export t_L(aux)。t_H(aux)And t_L(aux)Difference be t_vr。

(4) from fig. 4, it can be seen that drain-source voltage rising time t during underloading_vrCan be very big, if now selected according to measurement result Taking, dead band time setting is long, therefore needs to preset maximum Dead Time t_dt(max), when preventing loading too small, Dead Time is long, Affect changer output voltage quality and overall efficiency.

(5), after microcontroller collects the above-mentioned time, optimum Dead Time output t is selected according to formula (1)_dt(opt)。 Upper pipe cut-off signals s_HWith optimum Dead Time t_dt(opt)It is added and then opens signal S for down tube_L。

More than turn off situation for pipe upper in circuit shown in Fig. 1, situation when down tube turns off similarly, it is to be appreciated that down tube Gate source voltage t fall time_gs, channel current t fall time_cf, drain-source voltage rise time t_vr。

(1) down tube gate source voltage t fall time_gsCan be calculated by equivalent circuit as shown in Figure 3 and obtain.

(2) down tube channel current t fall time_cfBy prior off-line measurement load maximum, under the conditions of junction temperature high workload Channel current fall time.

(3) down tube drain-source voltage rise time t_vrNeed to measure in real time.The Dead Time optimal control electricity be given according to Fig. 7 Road schematic diagram, GVTD is down tube gate source voltage change detecting circuit, and DVFD is upper pipe drain-source voltage testing circuit (upper pipe drain-source electricity When pressure reduces to zero, down tube drain-source voltage i.e. rises to supply voltage).Marginal detector L is detected with certain frequency by GVTD Down tube gate source voltage, when down tube gate source voltage declines, marginal detector L exports s_L1, send into microcontroller through signal isolation circuit Device, down tube auxiliary adjustment circuit output feedback signal s in microcontroller_L(aux), feed back to edge inspection through down tube signal isolation circuit Survey device, improve detection frequency, prevent error detection.Now, down tube auxiliary adjustment circuit output t_L(aux).Similar, upper pipe auxiliary is adjusted Economize on electricity road, by pipe drain-source voltage trailing edge in DVFD detection, exports t_H(aux)。t_L(aux)And t_H(aux)Difference be t_vr。

(4) maximum Dead Time t is preset_dt(max), when preventing loading too small, Dead Time is long, affects changer output Quality of voltage and overall efficiency.

(5), after microcontroller collects the above-mentioned time, optimum Dead Time output t is selected according to formula (1)_dt(opt)。 Down tube cut-off signals s_LWith optimum Dead Time t_dt(opt)It is added and then opens signal S for upper pipe_H。

It is illustrated in figure 3 raster data model equivalent circuit, wherein: u_drFor drive voltage signal；R_GFor gate driver circuit etc. Effect resistance, for raster data model resistance and switching tube grid endophyte resistance sum；L_GFor grid circuit equivalent inductance, L_cmFor source Pole common mode inductance, L_G+L_cmIt is designated as L during calculating；C_issFor switching tube input capacitance；u_GSFor grid voltage.t_gsConcrete meter Calculation process is as follows:

Second-order circuit equation corresponding for Fig. 3 is:

${\mathrm{LC}}_{iss}\frac{d^2{u}_{GS}}{{\mathrm{dt}}^2}+R_G{C}_{iss}\frac{{\mathrm{du}}_{GS}}{dt}+u_{GS}=0$

Its characteristic equation is (characteristic equation is a kind of intermediary that second order differential equation solves):

LC_issp²+R_GC_issP+1=0

Its root is p₁、p₂:

$p_1=-\frac{R_G}{2L}+\sqrt{{\left(\frac{R_G}{2L}\right)}^2-\frac{1}{{\mathrm{LC}}_{iss}}}=-\mathrm{\δ}+\sqrt{{\mathrm{\δ}}^2-{\mathrm{\ω}}_0^2}$

$p_2=-\frac{R_G}{2L}-\sqrt{{\left(\frac{R_G}{2L}\right)}^2-\frac{1}{{\mathrm{LC}}_{iss}}}=-\mathrm{\δ}-\sqrt{{\mathrm{\δ}}^2-{\mathrm{\ω}}_0^2}$

Wherein,

Then, u_GSThe form solved is:

$u_{GS}=\frac{u_{dr}}{p_2-p_1}(p_2{e}^{p_{1}t}-p_1{e}^{p_{2}t})$

According to different situations, p₁、p₂Form different:

(1) whenTime:

p₁And p₂For not wait negative real root, then

$u_{GS}=\frac{u_{dr}}{p_2-p_1}(p_2{e}^{p_{1}t}-p_1{e}^{p_{2}t});$

(2) whenTime:

p₁And p₂It is a pair conjugation negative root, J is imaginary unit, then

$u_{GS}=\frac{u_{dr}}{-j2\mathrm{\ω}}\[-{\mathrm{\ω}}_0{e}^{j\mathrm{\θ}}{e}^{(-\mathrm{\δ}+j\mathrm{\ω})\·t}+{\mathrm{\ω}}_0{e}^{-j\mathrm{\θ}}{e}^{(-\mathrm{\δ}-j\mathrm{\ω})\·t\]};$

(3) whenTime:

p₁And p₂For repeated root,Then

u_GS=u_dre^-δt(1+δ·t)。

Above example is only the technological thought that the present invention is described, it is impossible to limit protection scope of the present invention with this, every The technological thought proposed according to the present invention, any change done on the basis of technical scheme, each fall within scope Within.

Claims (5)

1. the Dead Time optimal control method being applicable to SiC base brachium pontis power circuit, it is characterised in that this optimal control The switching tube drain-source voltage rise time t that real-time online measuring is obtained by method_vr, calculated grid voltage drop to threshold value The time t of voltage_gs, channel current t fall time that obtains of off-line measurement_cf, preset maximum Dead Time t_dt(max)The most defeated Entering in microcontroller, above-mentioned four kinds of times are compared by microcontroller according to the following formula that compares, and when exporting optimum dead band Between t_dt(opt)；The described formula that compares is:

$t_{dt\left(opt\right)}=min\left(max\right(t_{cf(I_{L\left(max\right)},T_{j\left(max\right)})},t_{vr},t_{gs}),t_{dt\left(max\right)}),$

Wherein,When representing load maximum, junction temperature high workload condition, the channel current that off-line measurement obtains declines Time.

The most according to claim 1, be applicable to the Dead Time optimal control method of SiC base brachium pontis power circuit, its feature exists In, described switching tube drain-source voltage rise time t_vrMeasuring method be:

In upper pipe circuit add gate source voltage testing circuit H, drain-source voltage testing circuit H, marginal detector H, on pipe auxiliary Regulation circuit, upper pipe signal isolation circuit；Gate source voltage testing circuit L, drain-source voltage testing circuit is added in down tube circuit L, marginal detector L, down tube auxiliary adjustment circuit, down tube signal isolation circuit；Whole SiC base brachium pontis power circuit adds Signal isolation circuit；

When upper pipe turns off, marginal detector H detects upper pipe gate source voltage by gate source voltage testing circuit H with certain frequency, When upper pipe gate source voltage declines, marginal detector H output pulse signal s_H1, send into upper pipe auxiliary adjustment through signal isolation circuit Circuit, upper pipe auxiliary adjustment circuit output feedback signal s_H(aux), feed back to marginal detector H through upper pipe signal isolation circuit, with Time, upper pipe auxiliary adjustment circuit output upper tube gate source voltage trailing edge t_H(aux)；In like manner, down tube auxiliary adjustment circuit passes through drain-source Voltage detecting circuit L detects down tube gate source voltage trailing edge t_L(aux), t_H(aux)And t_L(aux)Difference be t_vr；

When down tube turns off, marginal detector L detects down tube gate source voltage by gate source voltage testing circuit L with certain frequency, When down tube gate source voltage declines, marginal detector L output pulse signal s_L1, send into down tube auxiliary adjustment through signal isolation circuit Circuit, down tube auxiliary adjustment circuit output feedback signal s_L(aux), feed back to marginal detector L through down tube signal isolation circuit, with Time, down tube auxiliary adjustment circuit output lower tube gate source voltage trailing edge t_L(aux)；In like manner, upper pipe auxiliary adjustment circuit passes through drain-source Pipe drain-source voltage trailing edge t in voltage detecting circuit H detection_H(aux), t_L(aux)And t_H(aux)Difference be t_vr。

The most according to claim 1, be applicable to the Dead Time optimal control method of SiC base brachium pontis power circuit, its feature exists In, described grid voltage drops to the time t of threshold voltage_gsComputational methods be: according to raster data model equivalent circuit calculate can , described raster data model equivalent circuit by gate driver circuit equivalent resistance, grid circuit equivalent inductance, source electrode common mode inductance and The input capacitance of switching tube is in series.

The most according to claim 3, be applicable to the Dead Time optimal control method of SiC base brachium pontis power circuit, its feature exists In, described grid voltage drops to the time t of threshold voltage_gsTried to achieve by following second-order circuit equation:

${\mathrm{LC}}_{iss}\frac{d^2{u}_{GS}}{{{\mathrm{dt}}_{gs}}^2}+R_G{C}_{iss}\frac{{\mathrm{du}}_{GS}}{{\mathrm{dt}}_{gs}}+u_{GS}=0,$

Wherein, L is grid circuit equivalent inductance and source electrode common mode inductance sum, C_issFor the input capacitance of switching tube, u_GSFor grid Voltage, R_GFor gate driver circuit equivalent resistance.

The most according to claim 1, be applicable to the Dead Time optimal control method of SiC base brachium pontis power circuit, its feature exists In, channel current t fall time that described off-line measurement obtains_cfFor: under off-line state, junction temperature high workload maximum in load The channel current fall time that during condition, measurement obtains.