CN106100297A - Drive circuit based on silicon carbide MOSFET - Google Patents

Abstract

The present invention relates to a kind of drive circuit based on silicon carbide MOSFET.This drive circuit turn on and off loop through different loops, also include: four electric capacity C_{a1_H}、C_{a2_H}、C_{a1_L}And C_{a2_L}, electric capacity C_{a2_H}And C_{a2_L}Effect be to reduce common source stray inductance L on packaging pin_S2HAnd L_S2LImpact；Electric capacity C_{a1_H}And C_{a1_L}Effect be occur crosstalk time, for silicon carbide MOSFET encapsulation within junction capacity C_GDHAnd C_GDLCharging and discharging currents provide more low-impedance loop.The present invention can be used for the cross-interference issue in the current transformer suppressing to have bridge arm structure such as three-phase bridge type converter, full-bridge DC DC changer etc., on the premise of not increasing drive circuit complexity, inhibit the silicon carbide MOSFET gate-source voltage spike that cross-interference issue causes, improve the reliability of power electronic equipment based on silicon carbide MOSFET.

Description

Drive circuit based on silicon carbide MOSFET

Technical field

The invention belongs to Power Electronic Circuit technical field, relate to low shutoff grid return based on silicon carbide MOSFET resistance Anti-drive circuit.

Background technology

As it is shown in figure 1, add electric capacity C in traditional drive circuit based on silicon carbide MOSFET_{a_H}And C_{a_L}, for structure Build Low ESR branch road, the gate-source voltage spike that suppression cross-interference issue causes, but add electric capacity C_{a_H}And C_{a_L}Be equivalent to increase Grid source junction capacitance C_GSHAnd C_GSL, switching speed can be affected.Fig. 2 is given and a kind of based on silicon carbide MOSFET drives traditional Galvanic electricity road is added auxiliary switch S_{a_H}And S_{a_L}And electric capacity C_{a_H}And C_{a_L}, both can suppress the grid source electrode that cross-interference issue causes Due to voltage spikes, avoids only adding electric capacity C simultaneously_{a_H}And C_{a_L}The problem affecting silicon carbide MOSFET switching speed.Fig. 3 is in Fig. 2 The driving signal of corresponding switching tube.

The operation principle of prior art shown in Fig. 2 is as follows:

(t₀～t₁): electric capacity C_{a_H}And C_{a_L}Precharge.By auxiliary switch S_{a_H}、S_{a_L}Body diode and resistance R_{g_H}、R_{g_L}, electric capacity C_{a_H}And C_{a_L}Voltage be-V_{SS_H}With-V_{SS_L}。

(t₁～t₂): auxiliary switch S_{a_H}And S_{a_L}It is still within cut-off state.At t₂Moment, brachium pontis down tube Q₂Start to lead Logical.

(t₂～t₃): brachium pontis down tube Q₂Conducting.Now, switching tube S_{1_L}In the conduction state, Simultaneous Switching pipe S_{2_L}And auxiliary Switching tube S_{a_L}It is off state.Meanwhile, auxiliary switch S_{a_H}Conducting, electric capacity C_{a_H}It is connected in parallel on pipe Q on brachium pontis₁Electricity Hold C_GSHTwo ends, for the electric capacity C in switching process_GDHFor a Low ESR branch road.Pipe Q on brachium pontis₁Grid impedance significantly subtract Little, therefore, the forward voltage spike of grid source electrode reduces the most accordingly, opens the cross-interference issue that the moment causes and is inhibited.

(t₃～t₄): brachium pontis down tube Q₂Fully on.Electric capacity C_{a_H}And C_GSHBy resistance R_{g_H}With-V_{SS_H}Electricity, until Electric capacity C_{a_H}And C_GSHOn voltage drop to-V_{SS_H}Till.

(t₄～t₅): brachium pontis down tube Q₂Turn off.Switching tube S in the process_{1_L}Turn off, switching tube S_{2_L}Open-minded.Same with this Time, auxiliary switch S_{a_H}It is on stage, electric capacity C_{a_H}It is connected in parallel on pipe Q on brachium pontis₂Electric capacity C_GSHTwo ends.Pipe Q on brachium pontis₂'s Grid impedance is less, therefore can the negative voltage spike of effective suppressor source electrode.

(t₅～t₆): brachium pontis down tube Q₂Complete switch off.Auxiliary switch S_{a_H}Turn off, electric capacity C_{a_H}And C_GSHSeparated company Connect.Electric capacity C_GSHCharging, until its voltage rises to-V_{SS_H}Till.

Auxiliary switch S is added in the drive circuit shown in Fig. 2_{a_H}And S_{a_L}, need extra control signal to control Turning on and off of auxiliary switch, its shortcoming is mainly reflected in the following aspects:

1) auxiliary switch needs extra control signal, adds the complexity of control；

2) affecting the layout of drive circuit: due to auxiliary switch and the existence of electric capacity, the area of drive circuit increases, meeting Affect the switching characteristic of high-frequency circuit breaker in middle pipe.

When silicon carbide MOSFET is applied in high frequency bridge circuit, cross-interference issue can be produced, cause silicon carbide MOSFET There is forward spike or negative sense spike in gate-source voltage, as shown in Figure 4.Cross-interference issue is for the reliability of power electronic equipment Greatly, gate-source voltage forward spike can cause misleading of silicon carbide MOSFET, causes bridgc arm short in impact；And grid source electrode is electric Pressure negative sense spike can cause the grid source breakdown of silicon carbide MOSFET.Form the factor of cross-interference issue mainly by the parasitism of circuit Parameter causes, such as junction capacity C of silicon carbide MOSFET_GD(i.e. C in Fig. 1 and 2_GDHAnd C_GDL) and C_GS(i.e. C in Fig. 1 and 2_GSH And C_GSL), common source stray inductance (is concurrently present in drive circuit loop and main loop of power circuit).Whether drive circuit exists altogether Source stray inductance, determines different crosstalk phenomenons.Further, during existing technical scheme does not all consider device encapsulation, common source is parasitic The impact of inductance, and for it, braking measure is not taked in impact of cross-interference issue.

In sum, when prior art solves cross-interference issue, need to increase in the driving circuit auxiliary circuit, and assist electricity Auxiliary switch in road needs extra control signal, and control signal needs certain precision, can increase digital control Difficulty.And, after drive circuit adds auxiliary circuit, the layout of original drive circuit can be affected so that drive circuit Loop area increases.In high-frequency circuit, the increase of drive circuit loop area can affect the switching characteristic of switching tube.It addition, Existing technical scheme does not all consider the impact of stray inductance common source stray inductance in device encapsulation, and not for it to crosstalk Braking measure is taked in the impact of problem.

Summary of the invention

For defect present in prior art, it is an object of the invention to provide a kind of based on silicon carbide MOSFET drive Galvanic electricity road, has the crosstalk in the current transformer such as three-phase bridge type converter of bridge arm structure, full-bridge DC-DC converter etc. for suppression Problem.When cross-interference issue occurs, drive circuit provides Low ESR branch road, reduce gate-source voltage change.The present invention is not On the premise of increasing the complexity of drive circuit, it is suppressed that the silicon carbide MOSFET gate-source voltage spike that cross-interference issue causes, Improve the reliability of power electronic equipment based on silicon carbide MOSFET.

For reaching object above, the present invention adopts the technical scheme that:

A kind of drive circuit based on silicon carbide MOSFET, described silicon carbide MOSFET includes pipe Q on brachium pontis₁With under brachium pontis Pipe Q₂；Inductance L_S2HWith inductance L_S2LIt is respectively Q₁And Q₂The common source stray inductance of packaging pin；It is characterized in that:

The drive circuit of described silicon carbide MOSFET turn on and off loop through different loops, also include: four Electric capacity C_{a1_H}、C_{a2_H}、C_{a1_L}And C_{a2_L},

Electric capacity C_{a2_H}Effect be to reduce common source stray inductance L on packaging pin_S2HImpact, electric capacity C_{a2_H}It is connected in parallel on altogether Source stray inductance L_S2HWith the voltage source-V for providing shutoff negative pressure_{SS_H}On；

Electric capacity C_{a2_L}Effect be to reduce common source stray inductance L on packaging pin_S2LImpact, electric capacity C_{a2_L}It is connected in parallel on altogether Source stray inductance L_S2LWith the voltage source-V for providing shutoff negative pressure_{SS_L}On；

Electric capacity C_{a1_H}Effect be at Q₁When there is crosstalk, for junction capacity C within silicon carbide MOSFET encapsulation_GDHCharge and discharge Electricity electric current provides more low-impedance loop, electric capacity C_{a1_H}It is connected in parallel on Q₁Turn off resistance R_{off_H}On；

Electric capacity C_{a1_L}Effect be at Q₂When there is crosstalk, for junction capacity C within silicon carbide MOSFET encapsulation_GDLCharge and discharge Electricity electric current provides more low-impedance loop, electric capacity C_{a1_L}It is connected in parallel on Q₂Turn off resistance R_{off_L}On.

In above-mentioned drive circuit,

Q₁Drive circuit open loop through voltage source V_{GS_H}, switching tube S_{1_H}With open resistance R_{on_H}；

Q₁The turn-off circuit of drive circuit through voltage source-V_{SS_H}, switching tube S_{2_H}With shutoff resistance R_{off_H}；

Q₂Drive circuit open loop through voltage source V_{GS_L}, switching tube S_{1_L}With open resistance R_{on_L}；

Q₂The turn-off circuit of drive circuit through voltage source-V_{SS_L}, switching tube S_{2_L}With shutoff resistance R_{off_L}。

In above-mentioned drive circuit,

Q₁Drive circuit breaker in middle pipe S_{1_H}With switching tube S_{2_H}Driving signal is complementary；

Q₂Drive circuit breaker in middle pipe S_{1_L}With switching tube S_{2_L}Driving signal is complementary.

In above-mentioned drive circuit,

Q₁Encapsulation inside include grid source junction capacitance C_GSH, grid drain junction capacitance C_GDHWith leakage source junction capacitance C_DSH；

Q₂Encapsulation inside include grid source junction capacitance C_GSL, grid drain junction capacitance C_GDLWith leakage source junction capacitance C_DSL；

Q₁And Q₂Encapsulation internal connection line common source stray inductance be respectively inductance L_S1HWith inductance L_S1L；

Q₁And Q₂Internal gate resistance is respectively resistance R_G1HWith resistance R_G1L。

In above-mentioned drive circuit,

At Q₁When there is crosstalk, electric capacity C_{a1_H}Sufficiently large, make major part junction capacity C_GDHVariable-current will flow through electric capacity C_{a1_H}Rather than junction capacity C_GSH, Q₁On grid source electrode, due to voltage spikes will reduce；

At Q₂When there is crosstalk, electric capacity C_{a1_L}Sufficiently large, make major part junction capacity C_GDLVariable-current will flow through electric capacity C_{a1_L}Rather than junction capacity C_GSL, Q₂On grid source electrode, due to voltage spikes will reduce.

In above-mentioned drive circuit,

When electric current drastically changes, common source stray inductance L_S2HUpper sensing produces voltage drop and stores energy, now electric capacity C_{a2_H}Upper voltage and energy change the most therewith, as electric capacity C_{a2_H}Time sufficiently large, common source stray inductance L_S2HWith drive circuit Q₁Decoupling, Common source stray inductance L_S2HImpact reduce；

When electric current drastically changes, common source stray inductance L_S2LUpper sensing produces voltage drop and stores energy, now electric capacity C_{a2_L}Upper voltage and energy change the most therewith, as electric capacity C_{a2_L}Time sufficiently large, common source stray inductance L_S2LWith drive circuit Q₂Decoupling, Common source stray inductance L_S2LImpact reduce.

Having the beneficial effect that of drive circuit based on silicon carbide MOSFET of the present invention:

Fig. 5 is existing a kind of drive circuit, and its feature is that the drive circuit that silicon carbide MOSFET turns on and off returns Road is through different loops.Such as silicon carbide MOSFET Q₁When opening, its drive circuit is through voltage source V_{GS_H}, switching tube S_{1_H} With open resistance R_{on_H}；Silicon carbide MOSFET Q₁During shutoff, its drive circuit is through-V_{SS_H}、S_{2_H}And R_{off_H}.The present invention Four electric capacity C are increased on the basis of drive circuit shown in Fig. 5_{a1_H}、C_{a2_H}、C_{a1_L}And C_{a2_L}, as shown in Figure 6.The driving of the present invention Circuit can reduce the impact of common source stray inductance, can suppress again cross-interference issue, and without auxiliary switch, does not affect carborundum The normal switch speed of MOSFET, does not affect the layout of drive circuit, simple in construction, it is easy to accomplish, specific as follows:

The framework of the drive circuit of the lowest shutoff grid return impedance: the feature of this drive circuit is without extra active Device, on the premise of the purpose reaching suppression cross-interference issue, can not affect the normal switch speed of silicon carbide MOSFET, again The layout of drive circuit, simple in construction can not be affected, it is easy to accomplish.

2. electric capacity C_{a2_H}And C_{a2_L}Connected mode: electric capacity C_{a2_H}And C_{a2_L}Effect be to reduce the common source on packaging pin Stray inductance L_S2HAnd L_S2LImpact, electric capacity C_{a2_H}And C_{a2_L}Need to be connected in parallel on common source stray inductance and for providing shutoff negative pressure Voltage source-V_{SS_H}Or-V_{SS_L}On.

3. electric capacity C_{a1_H}And C_{a1_L}Connected mode: electric capacity C_{a1_H}And C_{a1_L}Effect be occur crosstalk time, for carborundum Junction capacity C within mosfet package_GDHAnd C_GDLCharging and discharging currents provide more low-impedance loop.Electric capacity C_{a1_H}And C_{a1_L}Phase As the electric capacity C in Fig. 1_{a_H}And C_{a_L}But, in order to avoid increasing auxiliary switch, electric capacity C_{a1_H}And C_{a1_L}It is connected in parallel on shutoff grid Electrode resistance R_{off_H}And R_{off_L}On, then utilize switching tube S_{2_H}And S_{2_L}Control it and do not affect silicon carbide MOSFET switching speed.

Accompanying drawing explanation

The present invention has a drawings described below:

Fig. 1 is the drive circuit of prior art；

Fig. 2 is improvement drive circuit based on prior art

Fig. 3 is the driving signal of Fig. 2 drive circuit correspondence switching tube；

Fig. 4 is the positive negative sense due to voltage spikes that cross-interference issue causes；

Fig. 5 is existing drive circuit；

Fig. 6 is the improvement drive circuit figure that the drive circuit present invention based on Fig. 5 proposes；

Fig. 7 is the drive circuit breaker in middle pipe S of the present invention_{1_H}、S_{2_H}、S_{1_L}And S_{2_L}Signal logic；

Fig. 8 is the equivalent circuit diagram of one switch periods four-stage of drive circuit of the present invention；Wherein, (a) is t₁-t₂ The equivalent circuit diagram in moment；B () is t₂-t₃The equivalent circuit diagram in moment；C () is t₃-t₄The equivalent circuit diagram in moment；D () is t₄- t₅The equivalent circuit diagram in moment；

Fig. 9 is for being used for calculating electric capacity C_{a1_H}Equivalent circuit.

Detailed description of the invention

Below in conjunction with accompanying drawing, the present invention is described in further detail.

Embodiment 1

1, the drive circuit (as shown in Figure 6) of the present invention.

Owing to cross-interference issue results from switching moments, it is believed that load current I_oWith input voltage V_DCConstant.Shown in Fig. 6 Drive circuit is to add four electric capacity C on the basis of drive circuit existing shown in Fig. 5_{a1_H}、C_{a2_H}、C_{a1_L}And C_{a2_L}, specifically As follows:

Q₁Drive circuit in S_{1_H}And S_{2_H}Driving signal is complementary, Q₂Drive circuit in S_{1_L}And S_{2_L}Driving signal is complementary；

Electric capacity C_GSH, electric capacity C_GDH, electric capacity C_DSHIt is respectively silicon carbide MOSFET Q₁Encapsulation internal grid source junction capacitance, grid Drain junction capacitance and leakage source junction capacitance；

Electric capacity C_GSL, electric capacity C_GDL, electric capacity C_DSLIt is respectively silicon carbide MOSFET Q₂Encapsulation internal grid source junction capacitance, grid Drain junction capacitance and leakage source junction capacitance；

Inductance L_S1HWith inductance L_S1LIt is respectively silicon carbide MOSFET Q₁And Q₂Encapsulation internal connection line common source parasitism electricity Sense；

Inductance L_S2HWith inductance L_S2LIt is respectively silicon carbide MOSFET Q₁And Q₂The common source stray inductance of packaging pin；

Resistance R_G1HWith resistance R_G1LIt is respectively silicon carbide MOSFET Q₁And Q₂Internal gate resistance；

Resistance R_{on_H}, resistance R_{off_H}It is respectively silicon carbide MOSFET Q₁Open resistance and turn off resistance；

Resistance R_{on_L}, resistance R_{off_L}It is respectively silicon carbide MOSFET Q₂Open resistance and turn off resistance.

2, drive circuit works principle

As it is shown in fig. 7, one switch periods of drive circuit of the present invention to be divided into four-stage: (t₁～t₂)、(t₂~ t₃)、(t₃～t₄) and (t₄～t₅), the equivalent circuit diagram in each stage as shown in Figure 8, is made a concrete analysis of as follows:

t₁Before moment, it is assumed that circuit is in steady statue.Drive circuit S_{2_H}And S_{2_L}Open-minded, Q₁And Q₂It is in turning off State, Q₁Body diode D₁Afterflow is carried out as fly-wheel diode.

(t₁～t₂): Q₁Drive circuit breaker in middle pipe S_{2_H}It is still within cut-off state, Q₂Drive circuit breaker in middle pipe S_{2_L}Turn off, switching tube S_{1_L}Open-minded, shown in this stage equivalent circuit such as Fig. 8 (a).This stage, Q₂Entrance conducting state, and Q₁One Directly it is off state.Due to Q in this stage₂Drive circuit in S_{2_L}It is off state, electric capacity C_{a1_L}It is not attached to out In logical loop, will not be to Q₂Speed of opening impact.At Q₂In opening process, Q₂With Q₁Body diode D₁During the change of current, electricity The pace of change of stream is very fast, common source stray inductance L_S1H、L_S2H、L_S1L、L_S2LOn all can produce voltage drop.Due to common source stray inductance L_S1HAnd L_S1LAs the stray inductance on silicon carbide MOSFET encapsulation internal links circuit, inductance value is less, ignores what it caused Impact.At Q₂Drive circuit in, electric capacity C_{a2_L}With common source stray inductance L_S2L, voltage source-V_{SS_L}Form loop.If electric capacity C_{a2_L} Sufficiently large, common source stray inductance L_S2LOn voltage drop impact reduce.Equally, at Q₁Drive circuit in, electric capacity C_{a2_H}Reduce Common source stray inductance L_S2HImpact.Q₂Q during opening₁And Q₂Drain-source voltage when simultaneously changing, junction capacity C_GDH、C_DSHWith C_GDL、C_DSLCarry out discharge and recharge.During this, Q₁Junction capacity C_GDHCharging current can flow through junction capacity C_GSHBranch road and driving In dynamic loop, if electric capacity C_{a1_H}Sufficiently large, major part junction capacity C_GDHCharging current will flow through electric capacity C_{a1_H}.To sum up, Q₁Grid source Extremely go up due to voltage spikes will reduce, it is achieved that the suppression to cross-interference issue.

(t₂～t₃): Q₁Drive circuit breaker in middle pipe S_{2_H}It is still within cut-off state, Q₂Drive circuit breaker in middle pipe S_{1_L}Turn off, switching tube S_{2_L}Open-minded, shown in this stage equivalent circuit such as Fig. 8 (b).This stage, Q₂Enter off state, Q₁Still It is off state.Q₂Drive circuit in S_{2_L}Open-minded, electric capacity C_{a1_L}With pass resistance break R_{off_L}It is connected in turn-off circuit, because of electricity Hold C_{a1_L}Relatively big, to Q₂The impact of turn-off speed negligible, Q₂Turn-off speed mainly by close resistance break R_{off_L}Regulation.At Q₂ Turn off process in, Q₁And Q₂Drain-source voltage when simultaneously changing, Q₁Junction capacity C_GDHDischarge current can flow through junction capacity C_GSH In branch road and drive circuit, due to electric capacity C_{a1_H}The impedance in loop, place is little, so major part electric capacity C_GDHCharging current flow through C_{a1_H}。Q₂During shutoff, Q₂With Q₁Body diode D₁During the change of current, electric current drastically changes, common source stray inductance L_S1H、L_S2H、 L_S1L、L_S2LOn all can produce voltage drop, and due to electric capacity C_{a2_H}And C_{a2_L}Impact, common source stray inductance L_S2HAnd L_S1HTo crosstalk The impact of problem reduces.

(t₃～t₄): Q₂Drive circuit breaker in middle pipe S_{1_L}It is still within cut-off state, Q₁Drive circuit breaker in middle pipe S_{2_H}Turn off, switching tube S_{1_H}Open-minded, shown in this stage equivalent circuit such as Fig. 8 (c).This stage Q₁Enter opening state, Q₂Locate always In off state.Owing to load current flows into brachium pontis midpoint, Q₁Opening process in, Q₁With its body diode D₁The change of current, Q₁And Q₂ Drain-source voltage the most unchanged, basic no-voltage curent change in common source stray inductance and junction capacity, so not havinging string Disturb problem.

(t₄～t₅): Q₂Drive circuit breaker in middle pipe S_{1_L}It is still within cut-off state, Q₁Drive circuit breaker in middle pipe S_{1_H}Turn off, switching tube S_{2_H}Open-minded, shown in this stage equivalent circuit such as Fig. 8 (d).This stage Q₁Enter off state, Q₂Locate always In off state.Q₁Turn off process similar to its opening process, Q₁With its body diode D₁The change of current, Q₁And Q₂Drain-source voltage base This is unchanged, and basic no-voltage curent change in source stray inductance and junction capacity, so not havinging cross-interference issue.

3, the parameter of drive circuit calculates

Q₁In drive circuit, parameter calculates:

1) electric capacity C_{a2_H}Calculating

Electric capacity C_{a2_H}Effect be to reduce common source stray inductance L on packaging pin_S2HImpact.When electric current drastically changes Time, common source stray inductance L_S2HUpper sensing produces voltage drop and stores energy, now electric capacity C_{a2_H}Upper voltage and energy are the most therewith Change；As electric capacity C_{a2_H}Time sufficiently large, common source stray inductance L_S2HWith Q₁Drive circuit decouples, common source stray inductance L_S2HImpact Reduce.

Set electric capacity C_{a2_H}Voltage variety Δ v_{Ca2_H}＜ Δ V_{Ca2_H}(ΔV_{Ca2_H}For setting value), then electric capacity C_{a2_H}Need full Condition shown in foot formula (1):

$|V_{SS\_H}^2-{(V_{SS\_H}+{\mathrm{\ΔV}}_{Ca2\_H})}^2|C_{a2\_H}\≥I_{peak}^2{L}_{S2H}---\left(1\right);$

In formula (1), I_peakFor current change quantity maximum on common source inductance.

2) electric capacity C_{a1_H}Calculating

Q₁When cross-interference issue occurs, electric capacity C_{a1_H}Sufficiently large, major part junction capacity C_GDHVariable-current will flow through electric capacity C_{a1_H}Rather than junction capacity C_GSH, Q₁On grid source electrode, due to voltage spikes will reduce.

Fig. 9 is Q₁Simple equivalent circuit during cross-interference issue occurs.Assume switching moments Q₁Drain-source voltage v_DSHElectricity Buckling rate κ is constant, Q₂κ=κ when opening₁, Q₂κ=κ during shutoff₂, formula (2) and (3) sets forth Q₂Q when opening₁Grid source The forward kurtosis v of pole tension_GSH(+), and Q₂Q during shutoff₁The negative sense kurtosis v of gate-source voltage_GSH(-).In order to ensure electric power The reliability of electronic installation, Q₁Gate-source voltage forward kurtosis v_GSH(+)Need less than the threshold voltage V of silicon carbide MOSFET_th, Negative sense kurtosis v_GSH(-)Need more than grid source electrode negative sense safe voltage V_{GS_MAX(-)}, as shown in formula (4).And according to formula (2) and (3) Understand, negative voltage V_{SS_H}For Q₁The kurtosis of gate-source voltage there is also impact, need to be according to formula (5) to V_{SS_H}Scope Select.

$v_{GSH(+)}=V_{SS\_H}+{\mathrm{\Δv}}_{GSH(+)}=V_{SS\_H}+{\mathrm{\κ}}_1(a_0+a_1{e}^{\frac{-V_{DC}}{{\mathrm{\τ}}_1{\mathrm{\κ}}_1}}+a_2{e}^{\frac{-V_{DC}}{{\mathrm{\τ}}_2{\mathrm{\κ}}_1}})---\left(2\right)$

$v_{GSH(-)}=V_{SS\_H}+{\mathrm{\Δv}}_{GSH(-)}=V_{SS\_H}+{\mathrm{\κ}}_2(a_0+a_1{e}^{\frac{V_{DC}}{{\mathrm{\τ}}_1{\mathrm{\κ}}_2}}+a_2{e}^{\frac{V_{DC}}{{\mathrm{\τ}}_2{\mathrm{\κ}}_2}})---\left(3\right)$

Δv_GSH(+)-Δv_GSH(-)＜ V_th-V_{GS_MAX(-)} (4)

V_{GS_MAX(-)}-Δv_GSH(-)＜ V_{SS_H}＜ V_th-Δv_GSH(+) (5)

In formula (2) (3):

Δv_GSH(+)For Q₁The positive change amount of gate-source voltage；

Δv_GSH(-)For Q₁The negative sense variable quantity of gate-source voltage；

a₀=τ_d；

$a_1=\frac{\mathrm{\λ}({\mathrm{\τ}}_a+{\mathrm{\τ}}_b-\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c})(\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c}-({\mathrm{\τ}}_a-{\mathrm{\τ}}_b\left)\right)}{4\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c}};$

$a_2=\frac{\mathrm{\λ}({\mathrm{\τ}}_a+{\mathrm{\τ}}_b+\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c})(\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c}+({\mathrm{\τ}}_a-{\mathrm{\τ}}_b\left)\right)}{4\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c}};$

${\mathrm{\τ}}_1=\frac{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)+\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c}}{2};$

${\mathrm{\τ}}_2=\frac{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)-\sqrt{{({\mathrm{\τ}}_a+{\mathrm{\τ}}_b)}^2-4{\mathrm{\τ}}_c}}{2};$

τ_a=R_{off_H}C_{a1_H}；

τ_b=(R_G1H+R_{off_H})(C_GSH+C_GDH)；

τ_c=R_G1HR_{off_H}C_{a1_H}(C_GSH+C_GDH)；

τ_d=(R_G1H+R_{off_H})C_GDH；

$\mathrm{\λ}=\frac{1}{1+\frac{C_{GSH}}{C_{GDH}}}.$

Q₂In drive circuit, parameter calculates:

3) electric capacity C_{a2_L}Computational methods

Electric capacity C_{a2_L}Effect be to reduce common source stray inductance L on packaging pin_S2LImpact.When electric current drastically changes Time, common source stray inductance L_S2LUpper sensing produces voltage drop and stores energy, now electric capacity C_{a2_L}Upper voltage and energy are the most therewith Change；As electric capacity C_{a2_L}Time sufficiently large, common source stray inductance L_S2LWith Q₂Drive circuit decouples, common source stray inductance L_S2LImpact Reduce.Electric capacity C_{a2_L}Computational methods and C_{a2_H}Identical.

4) electric capacity C_{a1_L}Calculating

Q₂When cross-interference issue occurs, electric capacity C_{a1_L}Sufficiently large, major part junction capacity C_GDLVariable-current will flow through electric capacity C_{a1_L}Rather than junction capacity C_GSL, Q₂On grid source electrode, due to voltage spikes will reduce.C_{a1_L}Computational methods and C_{a1_H}Identical.

The content not being described in detail in this specification belongs to prior art known to professional and technical personnel in the field.

Claims (6)

1. a drive circuit based on silicon carbide MOSFET, described silicon carbide MOSFET includes pipe Q on brachium pontis₁With brachium pontis down tube Q₂；Inductance L_S2HWith inductance L_S2LIt is respectively Q₁And Q₂The common source stray inductance of packaging pin；It is characterized in that:

The drive circuit of described silicon carbide MOSFET turn on and off loop through different loops, also include: four electric capacity C_{a1_H}、C_{a2_H}、C_{a1_L}And C_{a2_L},

Electric capacity C_{a2_H}Effect be to reduce common source stray inductance L on packaging pin_S2HImpact, electric capacity C_{a2_H}It is connected in parallel on common source to post Raw inductance L_S2HWith the voltage source-V for providing shutoff negative pressure_{SS_H}On；

Electric capacity C_{a2_L}Effect be to reduce common source stray inductance L on packaging pin_S2LImpact, electric capacity C_{a2_L}It is connected in parallel on common source to post Raw inductance L_S2LWith the voltage source-V for providing shutoff negative pressure_{SS_L}On；

Electric capacity C_{a1_H}Effect be at Q₁When there is crosstalk, for junction capacity C within silicon carbide MOSFET encapsulation_GDHDischarge and recharge electricity Stream provides more low-impedance loop, electric capacity C_{a1_H}It is connected in parallel on Q₁Turn off resistance R_{off_H}On；

Electric capacity C_{a1_L}Effect be at Q₂When there is crosstalk, for junction capacity C within silicon carbide MOSFET encapsulation_GDLDischarge and recharge electricity Stream provides more low-impedance loop, electric capacity C_{a1_L}It is connected in parallel on Q₂Turn off resistance R_{off_L}On.

2. drive circuit based on silicon carbide MOSFET as claimed in claim 1, it is characterised in that:

Q₁Drive circuit open loop through voltage source V_{GS_H}, switching tube S_{1_H}With open resistance R_{on_H}；

Q₁The turn-off circuit of drive circuit through voltage source-V_{SS_H}, switching tube S_{2_H}With shutoff resistance R_{off_H}；

Q₂Drive circuit open loop through voltage source V_{GS_L}, switching tube S_{1_L}With open resistance R_{on_L}；

Q₂The turn-off circuit of drive circuit through voltage source-V_{SS_L}, switching tube S_{2_L}With shutoff resistance R_{off_L}。

3. drive circuit based on silicon carbide MOSFET as claimed in claim 1 or 2, it is characterised in that: Q₁Drive circuit in Switching tube S_{1_H}With switching tube S_{2_H}Driving signal is complementary；

Q₂Drive circuit breaker in middle pipe S_{1_L}With switching tube S_{2_L}Driving signal is complementary.

4. drive circuit based on silicon carbide MOSFET as claimed in claim 1 or 2, it is characterised in that: Q₁The internal bag of encapsulation Include grid source junction capacitance C_GSH, grid drain junction capacitance C_GDHWith leakage source junction capacitance C_DSH；

Q₂Encapsulation inside include grid source junction capacitance C_GSL, grid drain junction capacitance C_GDLWith leakage source junction capacitance C_DSL；

Q₁And Q₂Encapsulation internal connection line common source stray inductance be respectively inductance L_S1HWith inductance L_S1L；

Q₁And Q₂Internal gate resistance is respectively resistance R_G1HWith resistance R_G1L。

5. drive circuit based on silicon carbide MOSFET as claimed in claim 4, it is characterised in that: at Q₁When there is crosstalk, electricity Hold C_{a1_H}Sufficiently large, make major part junction capacity C_GDHVariable-current will flow through electric capacity C_{a1_H}Rather than junction capacity C_GSH, Q₁Grid source Extremely go up due to voltage spikes will reduce；

At Q₂When there is crosstalk, electric capacity C_{a1_L}Sufficiently large, make major part junction capacity C_GDLVariable-current will flow through electric capacity C_{a1_L}, and It it not junction capacity C_GSL, Q₂On grid source electrode, due to voltage spikes will reduce.

6. drive circuit based on silicon carbide MOSFET as claimed in claim 4, it is characterised in that: when electric current drastically changes Time, common source stray inductance L_S2HUpper sensing produces voltage drop and stores energy, now electric capacity C_{a2_H}Upper voltage and energy are the most therewith Change, as electric capacity C_{a2_H}Time sufficiently large, common source stray inductance L_S2HWith drive circuit Q₁Decoupling, common source stray inductance L_S2HImpact Reduce；

When electric current drastically changes, common source stray inductance L_S2LUpper sensing produces voltage drop and stores energy, now electric capacity C_{a2_L} Upper voltage and energy change the most therewith, as electric capacity C_{a2_L}Time sufficiently large, common source stray inductance L_S2LWith drive circuit Q₂Decoupling, common source Stray inductance L_S2LImpact reduce.