CN107634649B - Switching device driving circuit and method and voltage conversion circuit - Google Patents
Switching device driving circuit and method and voltage conversion circuit Download PDFInfo
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- CN107634649B CN107634649B CN201710889803.0A CN201710889803A CN107634649B CN 107634649 B CN107634649 B CN 107634649B CN 201710889803 A CN201710889803 A CN 201710889803A CN 107634649 B CN107634649 B CN 107634649B
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Abstract
The invention discloses a switching device driving circuit, a switching device driving method and a voltage conversion circuit. The switching device driving circuit includes: a control circuit and a current supply circuit; wherein the control circuit is configured to generate three different control signals during the switching on of the switching device; the current supply circuit is configured to respond to each control signal and output corresponding driving current to the grid electrode of the switching device, so that the change of the grid-source voltage of the switching device in the opening process is matched with the grid-source voltage template curve of the switching device; and/or, the control circuit is configured to generate a first control signal during the switching device is turned off; the current supply circuit is configured to output corresponding driving current to the gate of the switching device in two or three stages in response to the first control signal, so that the change of the gate-source voltage of the switching device in the off process is matched with the gate-source voltage template curve of the switching device.
Description
Technical Field
The present invention relates to the field of electronics, and in particular, to a switching device driving circuit, a switching device driving method, and a voltage converting circuit.
Background
In recent years, with the advancement of power electronic device technology, especially the emergence of high frequency switching devices such as metal oxide semiconductor field effect transistors (MOFETs), power electronic devices have been increasingly miniaturized and have high performance.
However, when applied at high frequency, the switching action of the MOSFET may cause a ringing problem of voltage at the switching node of the power regulator, thereby generating a serious ElectroMagnetic Interference (EMI), which may affect the normal operation of other devices and even the service life of the MOSFET.
Although some conventional solutions to solve such problems are not efficient, some of the conventional solutions require additional external devices, which makes the power regulator larger in size, and some of the conventional solutions increase power loss.
Disclosure of Invention
In order to solve the existing technical problems, embodiments of the present invention provide a switching device driving circuit, a switching device driving method, and a voltage converting circuit.
The technical scheme of the embodiment of the invention is realized as follows:
an embodiment of the present invention provides a switching device driving circuit, including: a control circuit and a current supply circuit; wherein the content of the first and second substances,
the control circuit is configured to generate three different control signals during the on process of the switching device; the current supply circuit is configured to respond to each control signal and output corresponding driving current to the grid electrode of the switching device, so that the change of the grid-source voltage of the switching device in the opening process is matched with the grid-source voltage template curve of the switching device;
and/or the presence of a gas in the gas,
the control circuit is configured to generate a first control signal during the switching device is turned off; the current supply circuit is configured to output corresponding driving current to the gate of the switching device in two or three stages in response to the first control signal, so that the change of the gate-source voltage of the switching device in the off process is matched with the gate-source voltage template curve of the switching device.
In the above scheme, the control circuit is configured to output a second control signal when the gate-source voltage of the switching device does not reach a first threshold value in the on process of the switching device; when the grid-source voltage of the switching device is larger than the first threshold value and does not reach a second threshold value, outputting a third control signal; when the grid-source voltage of the switching device is larger than the second threshold value, outputting a fourth control signal;
the current supply circuit is configured to respond to the second control signal when receiving the second control signal, and output a driving current corresponding to the second control signal to the grid electrode of the switching device by using a current source; when the third control signal is received, responding to the third control signal, and outputting a driving current corresponding to the third control signal to the grid electrode of the switching device by using a current source; and when the fourth control signal is received, responding to the fourth control signal, and outputting the driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source.
In the above solution, the current providing circuit is configured to output a corresponding driving current to the gate of the switching device by using the first current source and the second current source when receiving the second control signal; outputting a corresponding driving current to a gate of the switching device by using the first current source when the third control signal is received; and outputting corresponding driving current to the grid electrode of the switching device by using the first current source and the third current source when the fourth control signal is received.
In the above scheme, the current supply circuit is configured in the switching-off process of the switching device, and outputs corresponding driving current to the gate of the switching device in two stages by using three MOS transistors.
In the above scheme, the three MOS transistors include: the MOS transistor comprises a first MOS transistor, a second MOS transistor and a third MOS transistor; the second MOS tube is connected with the third MOS tube in series;
in the switching-off process of the switching device, the current supply circuit outputs corresponding driving current for the grid electrode of the switching device by using first current flowing through a first MOS tube and second current flowing through a second MOS tube and a third MOS tube; the first current is a constant current; the second current is proportional to a square of a gate-source voltage of the switching device.
The embodiment of the invention also provides a voltage conversion circuit, which comprises a switching device arranged on an input-output path of the voltage conversion circuit, and a driving circuit of any one of the switching devices.
The embodiment of the invention also provides a switching device driving method, which comprises the following steps:
generating three different control signals to output corresponding driving current to a grid electrode of the switching device in the opening process of the switching device, so that the change of grid-source voltage of the switching device is matched with a grid-source voltage template curve of the switching device in the opening process;
and/or the presence of a gas in the gas,
and generating a first control signal in the closing process of the switching device to output corresponding driving current to the grid electrode of the switching device in at least two stages, so that the change of the grid-source voltage of the switching device is matched with the grid-source voltage template curve of the switching device in the closing process.
In the foregoing solution, the generating three different control signals to output corresponding driving currents to the gate of the switching device during the on-state of the switching device includes:
when the grid-source voltage of the switching device does not reach a first threshold value, outputting a second control signal so as to output a driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source; when the grid-source voltage of the switching device is larger than the first threshold value and does not reach a second threshold value, outputting a third control signal so as to output a driving current corresponding to the third control signal to the grid electrode of the switching device by using a current source; and when the grid-source voltage of the switching device is greater than the second threshold, outputting a fourth control signal so as to output a driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source.
In the above scheme, when the second control signal is received, the first current source and the second current source are used to output corresponding driving currents to the gate of the switching device; outputting a corresponding driving current to a gate of the switching device by using the first current source when the third control signal is received; and outputting corresponding driving current to the grid electrode of the switching device by using the first current source and the third current source when the fourth control signal is received.
In the foregoing solution, the generating a first control signal to output a corresponding driving current to the gate of the switching device in two or three stages in the switching-off process of the switching device includes:
outputting corresponding driving current for the grid electrode of the switching device by utilizing a first current flowing through a first MOS tube and a second current flowing through a series MOS tube and a third MOS tube; the first current is a constant current; the second current is proportional to a square of a gate-source voltage of the switching device.
According to the switching device driving circuit, the switching device driving method and the voltage conversion circuit, three different control signals are generated in the switching-on process of the switching device so as to output corresponding driving current to the grid electrode of the switching device, and therefore the change of the grid source voltage of the switching device is matched with the grid source voltage template curve of the switching device in the switching-on process; and/or generating a first control signal in the switching-off process of the switching device to output corresponding driving current to the grid electrode of the switching device in two stages or three stages, so that the change of the grid-source voltage of the switching device in the switching-off process is matched with the grid-source voltage template curve of the switching device. In the opening process of the switching device, driving current is output to a grid electrode of the switching device in a three-section mode; in the turn-off process of the switching device, two-section or three-section driving current is output to the grid electrode of the switching device, so that the grid source voltage of the switching device can be matched with a template curve, the EMI is greatly reduced, the switching speed of the switching device is greatly improved, and the power consumption is reduced.
Drawings
In the drawings, which are not necessarily drawn to scale, like reference numerals may describe similar components in different views. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed herein.
FIG. 1 is a waveform diagram illustrating a MOSFET turn-on process;
FIG. 2 is a waveform diagram illustrating the MOSFET turn-off process;
FIG. 3 is a schematic diagram of a driving circuit of a switching device according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a voltage converting circuit according to an embodiment of the present invention;
FIG. 5 is a schematic circuit diagram of an embodiment of the present invention;
FIG. 6 is a schematic diagram of a driving current waveform at the conducting stage of a switching device according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a driving current waveform at the turn-off stage of a switching device according to an embodiment of the present invention;
FIG. 8 shows the simulation results of buck circuits without the implementation of the present invention;
fig. 9 shows a simulation result of the buck circuit according to the embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
In implementing the present invention, the inventor finds the following two methods for solving the ringing problem of the switch node voltage:
in the first method, a snubber circuit (snubber circuit) is added to the switch node, and the resistance and capacitance in the snubber circuit are large and cannot be integrated in a chip, so that an additional external device is required, and the size of the power regulator is large.
In the second method, the driving current of the gate driving circuit is reduced, but the slower switching speed increases the power loss and is not efficient.
On the other hand, considering the characteristics of the MOSFET, as shown in fig. 1, the MOSFET on process may include: the method comprises three stages, namely a switching-on delay stage (t0< t < t1), a current commutation and Miller plateau stage (t1< t < t3) and a Miller effect ending to a switch full-on stage (t > t 3). And the MOSFET turn-off process can be understood as the reverse of the turn-on process, so as shown in fig. 2, the MOSFET turn-off process can include: conducting to the miller stage (t5< t < t6), the miller stage and current commutation stage (t6< t < t8) and the closing delay stage (t8< t), the driving current can be output in stages to realize the switching of the switching device.
Based on this, in various embodiments of the invention: generating three different control signals to output corresponding driving current to a grid electrode of the switching device in the opening process of the switching device, so that the change of grid-source voltage of the switching device is matched with a grid-source voltage template curve of the switching device in the opening process; and/or generating a first control signal in the switching-off process of the switching device to output corresponding driving current to the grid electrode of the switching device in two stages or three stages, so that the change of the grid-source voltage of the switching device in the switching-off process is matched with the grid-source voltage template curve of the switching device.
According to the scheme provided by the embodiment of the invention, in the opening process of the switch device, the three-section type is adopted to output the driving current to the grid electrode of the switch device; in the turn-off process of the switching device, two-section or three-section driving current is output to the grid electrode of the switching device, so that the grid source voltage of the switching device can be matched with a template curve, the EMI is greatly reduced, the switching speed of the switching device is greatly improved, and the power consumption is reduced.
It should be noted that, as used herein, the first and second … … only indicate elements in different positions, and do not limit the parameters or functions of the elements; or different parameters, but the size of the parameters is not limited.
As shown in fig. 3, the switching device driving circuit according to the embodiment of the present invention includes: a control circuit 31 and a current supply circuit 32; wherein the content of the first and second substances,
during the switching on of the switching device, the control circuit 31 generates three different control signals; the current supply circuit 32 outputs a corresponding driving current to the gate of the switching device in response to each control signal, so that the variation of the gate-source voltage of the switching device during the turn-on process matches the gate-source voltage template curve of the switching device.
In addition, during the off process of the switching device, the control circuit 31 generates a first control signal; the current supply circuit 32 outputs a corresponding driving current to the gate of the switching device in two stages or three stages in response to the first control signal, so that the change of the gate-source voltage of the switching device is matched with the gate-source voltage template curve of the switching device in the off process.
In practical applications, the switching device may be a MOSFET.
According to the scheme provided by the embodiment of the invention, in the opening process of the switch device, the three-section type is adopted to output the driving current to the grid electrode of the switch device; in the turn-off process of the switching device, two-section or three-section driving current is output to the grid electrode of the switching device, so that the grid source voltage of the switching device can be matched with a template curve, the voltage of a switching node can be effectively prevented from generating ringing in the current conversion and Miller platform stages, and the EMI (electro-magnetic interference) is greatly reduced; and the switching speed of the switching device is greatly improved in the delay stage and the stage from the Miller effect ending to the switch complete conduction (or the stage from the switch conduction to the Miller effect ending), and the power consumption is reduced.
As shown in fig. 1, the on process of the switching device includes: the method comprises three stages of a switching-on delay stage, a current conversion and Miller platform stage and a Miller effect end to switch complete conduction stage. Wherein the content of the first and second substances,
when t0<t<Stage t1, which is the turn-on delay stage of the switching device, i.e. the gate-source voltage of the switching device rises from 0V to the threshold voltage V of the switching deviceTHAt this stage, the switching device itself should be switched faster without a change in voltage and current, so that a larger driving current can be output to the gate of the switching device.
t1<t<the t3 stage is the current commutation and miller plateau stage. Wherein, t1<t<the stage t2 is a current commutation stage, i.e. the current of the switching device rises from 0A to the final output current IOAnd (5) stage. At t2<t<At stage t3, drain-source voltage V of switching deviceDSIs descending; the current commutation phase and the miller stage phase are respectively a current change phase and a voltage change phase, and in the current commutation phase and the miller stage phase, in order to prevent the switching node voltage from ringing caused by the excessively fast change rate of the current and the voltage, and thus generating EMI for other components in the power regulator, a small driving current needs to be output to the grid electrode of the switching device.
the period from the end of the miller effect to the full on of the switch is t > t3, and in this period, the switching device needs to be fully turned on quickly to reduce power loss and improve efficiency, so that a large driving current needs to be output to the gate of the switching device.
Based on this, in some embodiments, during the on process of the switching device, when the gate-source voltage of the switching device does not reach the first threshold, the control circuit 31 outputs the second control signal; the current supply circuit 32 outputs a driving current corresponding to the second control signal to the gate of the switching device by using a current source in response to the second control signal.
When the gate-source voltage of the switching device is greater than the first threshold value and does not reach the second threshold value, the control circuit 31 outputs a third control signal; the current supply circuit 32 outputs a driving current corresponding to the third control signal to the gate of the switching device using a current source in response to the third control signal.
When the gate-source voltage of the switching device is greater than the second threshold, the control circuit 31 outputs a fourth control signal; the current supply circuit 32 outputs a driving current corresponding to the first control signal to the gate of the switching device using a current source in response to the fourth control signal.
When the gate-source voltage of the switching device does not reach the first threshold, it is indicated that the switching device is in the on delay stage, so that the driving current corresponding to the second control signal is a large current.
When the gate-source voltage of the switching device is equal to or lower than the first threshold value and is lower than the second threshold value, it is determined that the switching device is in a current commutation and miller plateau stage, that is, a stage in which the current and the voltage are changed, so that the driving current corresponding to the third control signal is a small current.
When the gate-source voltage of the switching device is greater than the second threshold, it is indicated that the switching device is in a stage from the end of the miller effect to the complete conduction of the switch, and the miller effect is ended at this time, so that the driving current corresponding to the second control signal is a large current.
Therefore, the driving current corresponding to the second control signal and the driving current corresponding to the fourth control signal are both greater than the driving current corresponding to the third control signal.
Here, in practical application, the first threshold and the second threshold may be set as needed, and the size of the switching device needs to be considered in setting. For example, assume that the threshold voltage of the switching device is VTHCorresponding Miller plateau voltage of VGPThe first threshold value may be set to VTHThe second threshold value may be set to the ratio VGPA slightly larger voltage value.
In the opening process of the switching device, a three-section type is adopted to output a driving current to the grid electrode of the switching device, and when the grid source voltage of the switching device is greater than the first threshold value and does not reach a second threshold value, a small driving current is output to the grid electrode of the switching device, so that the voltage of a switching node can be effectively prevented from generating ringing phenomena in the current conversion and Miller platform stages, and further EMI is greatly reduced; and in the delay stage and the Miller effect ending to the switch complete conduction stage, namely when the grid-source voltage of the switch device does not reach the first threshold value and the grid-source voltage of the switch device is greater than the second threshold value, outputting a large driving current to the grid electrode of the switch device, thereby greatly improving the switching speed of the switch device and reducing the power consumption.
As shown in fig. 2, the off process of the switching device includes: the method comprises a Miller platform stage, a Miller platform and current conversion stage and a closing delay stage. Wherein the content of the first and second substances,
the period t5< t < t6 is a period from the on state of the switching device to the miller plateau, and in this period, the switching device needs to be turned off quickly to reduce power loss and improve efficiency, so that a larger driving current needs to be output to the gate of the switching device.
t6<t<the t8 stage is the current commutation and miller plateau stage. Wherein, t6<t<t7 is the Miller plateau phase where the drain-source voltage V of the switching deviceDSIs ascending; t7<t<the stage t8 is a current commutation stage, i.e. the current of the switching device is changed from the final output current IOA stage of falling to 0A; the current commutation phase and the miller stage phase are respectively a current change phase and a voltage change phase, and in the current commutation phase and the miller stage phase, in order to prevent the switching node voltage from ringing caused by the excessively fast change rate of the current and the voltage, and thus generating EMI for other components in the power regulator, a small driving current needs to be output to the grid electrode of the switching device.
t8<the t stage is a switch device closing delay stage, namely the gate-source voltage of the switch device is controlled by the threshold voltage V of the gate source of the switch deviceTHAnd the voltage is reduced to 0V stage, in which the switching device has no voltage current change, and the switching speed should be increased, so that a larger driving current can be output to the gate of the switching device.
Based on this, in some embodiments, during the switching device off process, the current supply circuit 32 outputs the corresponding driving current to the gate of the switching device in two stages by using three MOS transistors.
Specifically, the three MOS transistors include: the MOS transistor comprises a first MOS transistor, a second MOS transistor and a third MOS transistor; the second MOS tube is connected with the third MOS tube in series;
in the switching device off process, the current supply circuit 32 outputs a corresponding driving current to the gate of the switching device by using a first current flowing through the first MOS transistor and a second current flowing through the second MOS transistor and the third MOS transistor; the first current is a constant current; the second current is proportional to a square of a gate-source voltage of the switching device.
In the switching-off process of the switching device, two-stage type is adopted to output driving current to the grid electrode of the switching device, and by utilizing the relation between the second current and the grid source voltage of the switching device, the grid source voltage of the switching device is already reduced and the second current and the grid source voltage form an exponential relation in the current conversion and Miller platform stage, so that the second current is smaller, the sum of the first current and the second current is reduced, the output driving current is reduced, the voltage of a switching node can be effectively prevented from generating ringing phenomenon, and the EMI is greatly reduced; and in the stage of conducting to the Miller platform, the grid source voltage is just opened and just decreased, and the second current and the grid source voltage form an indication relation, so the sum of the first current and the second current is still a large current, and a large driving current is output to the grid electrode of the switching device, thereby greatly improving the switching speed of the switching device and reducing the power consumption.
The scheme of the embodiment of the invention can be applied to voltage conversion circuits, such as boost circuits, buck circuits and the like. Wherein the boost circuit may include synchronous and asynchronous boost circuits; accordingly, the buck circuit may include: synchronous and asynchronous buck circuits.
When applied to a voltage conversion circuit, particularly a Direct Current (DC) to DC voltage conversion circuit, the switching device is disposed on an input-to-output path of the voltage conversion circuit, and as shown in fig. 4, the voltage conversion circuit includes: a switching device 41. Of course, the voltage conversion circuit also includes a switching device driving circuit shown in fig. 3.
The switching device driving circuit shown in fig. 3 has been described in detail above, and is not described in detail here.
The invention will be further described with reference to an application example.
In the embodiment of the present application, the voltage conversion circuit is a synchronous buck circuit. As shown in fig. 5, the basic components of the buck circuit include: inductor L, MOS is a MOSFET MNP, MOS LS and capacitor Cout. Of course, a driver LSDriver provides a driving voltage or current for the second NMOS LS.
The first MOS tube MNP is a power switch device.
As shown in fig. 5, the control circuit 31 includes: an inverter INV1, comparators CMP1 and CMP 2;
a current providing circuit 32 comprising: current sources I1, I2, I3, and low-voltage MOS transistors (MOSFET) MN1, MN2, MN 3.
In practical application, the MNP is a power tube, and the voltage thereof can be 16V, 20V, 30V or more; the MOS transistors MN1, MN2, and MN3 are low-voltage transistors, i.e., common MOS transistors, and the voltage thereof may be 5V or 6V.
Assume a first threshold value VTHLIs the threshold voltage V of the MNP of the MOS tubeTHSecond threshold value VTHHGreater than the MNP Miller platform voltage V of the MOS tubeGP。
In the following description, the current of the current source I1 is referred to as I1; the current of the current source I2 is called I2; the current of the current I3 is called I3; the current flowing through the MOS transistor MN1 is called I4; the current flowing through the MOS transistors MN2 and MN3 is referred to as I5.
The operating principle of the circuit shown in fig. 5 is:
when the MOS transistor MNP needs to be turned on, the inverter INV1 receives the high voltage signal, and outputs the low voltage signal to the current source I1 after inversion, so that the current source I1 is turned on; the low-voltage signals output at the same time cause the MOS tubes MN1, MN2 and MN3 to be turned off; thereafter, during the opening of the MOS transistor MNP:
when the gate source voltage V of the MNP of the MOS tubeGSLess than a first threshold value VTHLAt this time, the comparator CMP1 outputs a high voltage signal, causing the current source I2 to turn on; at the same time, the comparator CMP2 outputs a low voltage signal, which causes the current source I3 to turn off, and at this stage, the current sources I1 and I2 output driving currents to the gates of the MOS transistors MNP. This stage corresponds to the turn-on delay stage shown in FIG. 1, i.e., t0<t<And (t 1). As shown in fig. 6, the driving current output to the gate of the MOS transistor MNP at this stage is I1+ I2;
when the gate source voltage V of the MNP of the MOS tubeGSGreater than a first threshold value VTHLAnd is less than a second threshold value VTHHAt this time, the comparator CMP1 outputs a low voltage signal, causing the current source I2 to turn off; meanwhile, the comparator CMP2 outputs a low voltage signal, which causes the current source I3 to turn off, and a driving current is output from the current source I1 to the gate of the MOS transistor MNP at this stage. This stage corresponds to the current commutation and miller plateau stage shown in fig. 1, i.e., t1<t<And (t 4). As shown in fig. 6, the driving current output to the gate of the MOS transistor MNP at this stage is I1;
when the gate source voltage V of the MNP of the MOS tubeGSGreater than a second threshold value VTHHAt this time, the comparator CMP1 outputs a low voltage signal, causing the current source I2 to turn off; at the same time, the comparator CMP2 outputs a high voltage signal, which turns on the current source I3, and at this stage, the current source I1 and the current source I3 output a driving current to the gate of the MOS transistor MNP. This stage corresponds to the miller shown in fig. 1The effect ends up in the fully on phase of the switch, t4<In the t phase, as shown in fig. 6, the driving current output to the gate of the MOS transistor MNP in this phase is I1+ I3.
As can be seen from the above-described process, the current supply circuit 32 comprises three current sources, and when receiving the second control signal (i.e. the gate-source voltage V of the MOS transistor MNP)GSLess than a first threshold value VTHLAt the time of the high voltage signal output from the comparator CMP1 and the low voltage signal output from the comparator CMP 2), the corresponding driving current (I1+ I2) is output to the gate of the switching device (i.e., the MOS transistor MNP) by the first current source and the second current source (corresponding to the current sources I1 and I2 described above); when receiving the third control signal (i.e. when the gate-source voltage V of the MOS transistor MNP)GSGreater than a first threshold value VTHLAnd is less than a second threshold value VTHHA low voltage signal output by the comparator CMP1 and a low voltage signal output by the comparator CMP 2), a corresponding drive current (I1) is output to the gate of the switching device by the first current source; when receiving the fourth control signal (i.e. when the gate-source voltage V of the MOS transistor MNP)GSGreater than a second threshold value VTHHAt the time of the second operation, the low voltage signal output from the comparator CMP1 and the high voltage signal output from the comparator CMP 2) are output to the gate of the switching device by the first current source and the third current source (corresponding to the current source I3 described above), and the corresponding drive current (I1+ I3) is output to the gate of the switching device.
In the process of opening the MOS tube MNP, in the switching-on delay stage of the MOS tube MNP, large current (i.e. I1+ I2) is output to the grid electrode of the MOS tube MNP, so that the switching speed of a switching device can be greatly improved; in the current conversion and miller platform stage, a small current (i.e. I1) is output to the gate of the MOS transistor MNP, so that the voltage of a switch node can be effectively prevented from generating a ringing phenomenon in the current conversion and miller platform stage, and further EMI is greatly reduced; in the stage from the end of the miller effect to the complete conduction of the switch, a large current (i.e., I1+ I3) is output to the gate of the MOS transistor MNP, so that the switching speed of the switching device can be greatly increased, and the power consumption is reduced.
Wherein, in practical application, if the second threshold value V is usedTHHThe MNP Miller platform voltage V of the MOS tube is larger than and close toGPAnd then t4 is close to t3, and the obtained output current is an ideal three-segment driving current waveform, and has the characteristics of small interference and low loss.
When the MOS transistor MNP needs to be turned off, the inverter INV1 receives the low voltage signal, outputs the high voltage signal to the current source I1 after inversion, and causes the current source I1 to be turned off; the high-voltage signals output at the same time cause the MOS tubes MN1, MN2 and MN3 to be conducted; then in the process of switching off the MOS tube MNP:
after the MOS transistors MN1, MN2, and MN3 are turned on, the driving current output to the gate of the MOS transistor MNP is: i4+ I5.
Specifically, in conjunction with fig. 2, there are:
in a stage t5< t < t6, the drive current output to the gate of the MOS transistor MNP is I4+ I5(t5 to t 6);
in a stage t6< t < t7, the drive current output to the gate of the MOS transistor MNP is I4+ I5(t6 to t 7);
in a stage t7< t < t8, the drive current output to the gate of the MOS transistor MNP is I4+ I5(t7 to t 8);
in the period t > t8, the driving current output to the gate of the MOS transistor MNP is I4+ I5.
Wherein, after the conduction, the MOS transistor MN 1VGSThe current flowing through the MOS transistor MN1 during the off period of the MOS transistor MNP remains constant. Since the MOS transistor MN2 is always operated in the saturation region during the period, the gate-source voltage V of I5 and the MOS transistor MNPGSIs proportional to the square ofThus, in conjunction with fig. 7, it can be concluded that:
in the period from t5 to t6, namely the period of conducting to the Miller platform, the gate-source voltage V of the MOS transistor MNP is causedGSIs also relatively large, I5 and the gate-source voltage VGSThe I5 is larger due to an exponential relationship, so that the driving current output to the gate of the MOS transistor MNP at the stage is larger, the switching speed of a switching device can be greatly improved, the power consumption is reduced, and the efficiency is improved.
At the stage t 6-t 8, namely the current commutation and Miller stage, the gate source of the MOS transistor MNPVoltage VGSHas dropped, and I5 is connected to the gate-source voltage VGSThe I5 is relatively small, so that the driving current output to the gate of the MOS transistor MNP at the stage is relatively small, the ringing phenomenon of the voltage of the switch node can be effectively prevented at the current conversion and Miller platform stages, and the EMI is greatly reduced.
Where β is a process related parameter.
As can be seen from the above-described process, the current supply circuit 32 utilizes three MOS transistors MN1, MN2, and MN3 to achieve the purpose of outputting the driving current to the MOS transistor MNP in two stages. Specifically, in the stage that the MOS tube MNP is conducted to the Miller platform, large current is output to the grid electrode of the MOS tube MNP, so that the switching speed of a switching device can be greatly improved, and the power consumption is reduced; in the current conversion and Miller platform stage, a small current is output to the gate of the MOS transistor MNP, so that the ringing phenomenon of the voltage of a switch node can be effectively prevented in the current conversion and Miller platform stage, and the EMI is greatly reduced.
The three tubes are used to achieve the purposes of low EMI and low power loss. In the process of switching off the switching device, the output driving current of the grid driving method is two-section driving, and the circuit is simple and easy to realize.
Based on the circuit, the embodiment of the invention also provides a switching device driving method, which comprises the following steps:
generating three different control signals in the opening process of the switching device to output corresponding driving current to the grid electrode of the switching device, so that the change of the grid-source voltage of the switching device in the opening process is matched with the grid-source voltage template curve of the switching device.
And generating a first control signal in the closing process of the switching device to output corresponding driving current to the grid electrode of the switching device in at least two stages, so that the change of the grid-source voltage of the switching device is matched with the grid-source voltage template curve of the switching device in the closing process.
In some embodiments, the generating three different control signals to output corresponding driving currents to the gates of the switching devices during the switching on of the switching devices includes:
when the grid-source voltage of the switching device does not reach a first threshold value, outputting a second control signal so as to output a driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source; when the grid-source voltage of the switching device is larger than the first threshold value and does not reach a second threshold value, outputting a third control signal so as to output a driving current corresponding to the third control signal to the grid electrode of the switching device by using a current source; and when the grid-source voltage of the switching device is greater than the second threshold, outputting a fourth control signal so as to output a driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source.
In some embodiments, when receiving the second control signal, outputting a corresponding driving current to the gate of the switching device by using a first current source and a second current source; outputting a corresponding driving current to a gate of the switching device by using the first current source when the third control signal is received; and outputting corresponding driving current to the grid electrode of the switching device by using the first current source and the third current source when the fourth control signal is received.
In some embodiments, the generating a first control signal to output a corresponding driving current to the gate of the switching device in two or three stages during the switching-off of the switching device includes:
outputting corresponding driving current for the grid electrode of the switching device by utilizing a first current flowing through a first MOS tube and a second current flowing through a series MOS tube and a third MOS tube; the first current is a constant current; the second current is proportional to a square of a gate-source voltage of the switching device.
Meanwhile, in order to better illustrate the technical scheme of the embodiment of the invention, a circuit where the switching device is located can be effectively protected, simulation experiments are carried out by using a buck circuit which does not comprise the scheme of the embodiment of the invention and comprises the scheme of the embodiment of the invention. Fig. 8 shows simulation results of a buck circuit (not shown) not including an embodiment of the invention, and fig. 9 shows simulation results of a buck circuit (the circuit shown in fig. 5) including an embodiment of the invention. As can be seen from the figure, in the starting process of the buck circuit without the embodiment of the present invention, the amplitude of the waveform oscillation of the SW node (switching node) is relatively large, and the oscillation duration is relatively long; in the starting process of the buck circuit adopting the scheme of the embodiment of the invention, the amplitude of the waveform oscillation of the SW node is smaller, and the oscillation duration is shorter; the smaller the amplitude of the waveform oscillation is and the shorter the oscillation duration is, the better the performance of the EMI is, namely, the technical scheme of the embodiment of the invention can effectively reduce the EMI. In fig. 8 and 9, VGS _ HS represents the gate-source voltage of the MOS transistor MNP in the circuit shown in fig. 5, I _ gate represents the charging current of the gate of the MOS transistor MNP in the circuit shown in fig. 5, and IL represents the current flowing through the inductor L.
It should be noted that: the technical schemes described in the embodiments of the present invention can be combined arbitrarily without conflict.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.
Claims (7)
1. A switching device driving circuit, comprising: a control circuit and a current supply circuit; wherein the content of the first and second substances,
the control circuit is configured to generate a first control signal during the switching device is turned off; the current providing circuit is configured to respond to the first control signal and output corresponding driving current to the grid electrode of the switching device in two stages or three stages, so that the change of the grid-source voltage of the switching device is matched with the grid-source voltage template curve of the switching device in the closing process;
alternatively, the first and second electrodes may be,
the control circuit is configured to generate three different control signals during the on process of the switching device; the current supply circuit is configured to respond to each control signal and output corresponding driving current to the grid electrode of the switching device, so that the change of the grid-source voltage of the switching device in the opening process is matched with the grid-source voltage template curve of the switching device; and the number of the first and second groups,
the control circuit is configured to generate a first control signal during the switching device is turned off; the current providing circuit is configured to respond to the first control signal and output corresponding driving current to the grid electrode of the switching device in two stages or three stages, so that the change of the grid-source voltage of the switching device is matched with the grid-source voltage template curve of the switching device in the closing process;
the current supply circuit is configured in the switching-off process of the switching device, and outputs corresponding driving current to the grid electrode of the switching device in two stages or three stages by using three MOS (metal oxide semiconductor) tubes;
the three MOS tubes include: the MOS transistor comprises a first MOS transistor, a second MOS transistor and a third MOS transistor; the second MOS tube is connected with the third MOS tube in series;
in the switching-off process of the switching device, the current supply circuit outputs corresponding driving current for the grid electrode of the switching device by using first current flowing through a first MOS tube and second current flowing through a second MOS tube and a third MOS tube; the first current is a constant current; the second current is proportional to a square of a gate-source voltage of the switching device.
2. The circuit of claim 1,
the control circuit is configured to output a second control signal when the gate-source voltage of the switching device does not reach a first threshold value in the switching-on process of the switching device; when the grid-source voltage of the switching device is larger than the first threshold value and does not reach a second threshold value, outputting a third control signal; when the grid-source voltage of the switching device is larger than the second threshold value, outputting a fourth control signal;
the current supply circuit is configured to respond to the second control signal when receiving the second control signal, and output a driving current corresponding to the second control signal to the grid electrode of the switching device by using a current source; when the third control signal is received, responding to the third control signal, and outputting a driving current corresponding to the third control signal to the grid electrode of the switching device by using a current source; and when the fourth control signal is received, responding to the fourth control signal, and outputting the driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source.
3. The circuit of claim 2,
the current supply circuit is configured to output corresponding driving currents to the gate of the switching device by using a first current source and a second current source when receiving the second control signal; outputting a corresponding driving current to a gate of the switching device by using the first current source when the third control signal is received; and outputting corresponding driving current to the grid electrode of the switching device by using the first current source and the third current source when the fourth control signal is received.
4. A voltage conversion circuit comprising a switching device provided on an input to output path of the voltage conversion circuit, the voltage conversion circuit further comprising a switching device driving circuit according to any one of claims 1 to 3.
5. A switching device driving method, characterized in that the method comprises:
generating a first control signal in the closing process of the switching device, and outputting corresponding driving current to the grid electrode of the switching device in at least two stages, so that the change of the grid-source voltage of the switching device is matched with the grid-source voltage template curve of the switching device in the closing process;
alternatively, the first and second electrodes may be,
generating three different control signals to output corresponding driving current to a grid electrode of the switching device in the opening process of the switching device, so that the change of grid-source voltage of the switching device is matched with a grid-source voltage template curve of the switching device in the opening process; and the number of the first and second groups,
generating a first control signal in the closing process of the switching device, and outputting corresponding driving current to the grid electrode of the switching device in at least two stages, so that the change of the grid-source voltage of the switching device is matched with the grid-source voltage template curve of the switching device in the closing process;
wherein, in the process of turning off the switching device, generating a first control signal to output a corresponding driving current to the gate of the switching device in two or three stages, includes:
outputting corresponding driving current for the grid electrode of the switching device by using first current flowing through a first MOS tube and second current flowing through a second MOS tube and a third MOS tube which are connected in series; the first current is a constant current; the second current is proportional to a square of a gate-source voltage of the switching device.
6. The method of claim 5, wherein generating three different control signals to output corresponding driving currents to the gates of the switching devices during the switching devices are turned on comprises:
when the grid-source voltage of the switching device does not reach a first threshold value, outputting a second control signal so as to output a driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source; when the grid-source voltage of the switching device is larger than the first threshold value and does not reach a second threshold value, outputting a third control signal so as to output a driving current corresponding to the third control signal to the grid electrode of the switching device by using a current source; and when the grid-source voltage of the switching device is greater than the second threshold, outputting a fourth control signal so as to output a driving current corresponding to the first control signal to the grid electrode of the switching device by using a current source.
7. The method of claim 6, wherein when receiving the second control signal, outputting a corresponding driving current to the gate of the switching device by using a first current source and a second current source; outputting a corresponding driving current to a gate of the switching device by using the first current source when the third control signal is received; and outputting corresponding driving current to the grid electrode of the switching device by using the first current source and the third current source when the fourth control signal is received.
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| CN115603549B (en) * | 2022-12-15 | 2023-03-31 | 苏州至盛半导体科技有限公司 | Self-adaptive grading driving method and circuit of MOSFET (Metal-oxide-semiconductor field Effect transistor) |
| CN116191843B (en) * | 2023-04-26 | 2023-07-25 | 广东华芯微特集成电路有限公司 | Gate driving circuit architecture, control method and BLDC motor driving circuit |
| CN116647219A (en) * | 2023-04-27 | 2023-08-25 | 北京芯可鉴科技有限公司 | IGBT driving circuit, method for driving IGBT and chip |
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