Driving current adjusting circuit and driving current adjusting method of power tube

Abstract

The invention discloses a driving current adjusting circuit and a driving current adjusting method of a power tube, and the driving current adjusting circuit comprises a current providing circuit which provides a first current for the power tube in a first time period after the power tube is conducted; the characterization value acquisition circuit is used for acquiring a characterization value for characterizing the turn-on speed of the power tube according to the detection signal of the power tube; and the current control circuit is used for generating an adjusting control signal according to the characterization value and a reference value for characterizing the set speed to adjust the size of the first current so as to adjust the driving current of the power tube. The first current is increased when it is detected that the turn-on speed is less than the set speed, and the first current is decreased when it is detected that the turn-on speed is greater than the set speed. And the turn-on speed of the power tube is controlled by adjusting the driving current in the first time period after the power tube is turned on, the electromagnetic compatibility is optimized, and the power tube switching device can adapt to different types of power tubes.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a driving current regulation circuit and a driving current regulation method for a power tube. Background Art

[0002] A switching power supply is a power supply that uses a power tube to control the charging and discharging process of an energy storage element to provide power, and maintains a stable output voltage and / or output current by controlling the on and off time ratio of the power tube.

[0003] Figure 1a A schematic diagram of a conventional power tube drive current regulation circuit is shown. Figure 1b Shows Figure 1a The waveform diagram of some signals of the current regulation circuit. Figure 1a As shown, it is a totem pole circuit of a conventional driver chip, including an upper driver tube M2 and a lower driver tube M3, which are alternately turned on and off to provide a driving voltage Gate for the power tube M1 of the switching power supply. When the upper driver tube M2 is turned on, the driving voltage Gate of the power tube M1 is at a high level, and when the lower driver tube M3 is turned on, the driving voltage Gate of the power tube M1 is at a low level. The driving voltage Gate obtains the divided voltage Vg1 through the divided voltage Ru and Rd, and then compares it with the reference voltage VREF through the operational amplifier EA to pull down the control terminal current of the transistor M2, thereby pulling down the driving current Ich, and performing clamping control.

[0004] like Figure 1b As shown in the figure, the current power tubes mostly use segmented drive current technology to drive soft start, and the drive current of the main power tube M1 is determined by the saturation current of the upper drive tube M2. Figure 1b In the example, at time t1, the power tube M1 is driven with a large current to increase the driving voltage Gate. In the time period t2-t3, the driving current reaches the maximum flow, passes the Miller platform of the power tube M1, and the current begins to decrease after the Miller platform. During the Miller platform, the slope of the drain-source voltage Vds of the power tube is very fast, and the radiation and EMC performance are poor. Moreover, since the driving current is fixed, it is impossible to achieve adaptive adaptation of power tubes of different levels. In the actual system, it is necessary to increase the peripheral PIN pin to set the driving current of different gears to achieve the purpose of adapting different power tubes, which is costly. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a driving current regulation circuit and a driving current regulation method for a power tube to solve the problems in the prior art.

[0006] According to one aspect of the present invention, there is provided a driving current regulating circuit for a power tube, comprising: a current supply circuit, for supplying a first current to the power tube within a first time period after the power tube is turned on; a characterization value acquisition circuit, for acquiring a characterization value characterizing a turn-on speed of the power tube according to a detection signal of the power tube; and a current control circuit, for generating a regulation control signal according to the characterization value and a reference value to adjust the magnitude of the first current generated by the current supply circuit, so as to adjust the magnitude of the driving current of the power tube, wherein when the current control circuit detects that the turn-on speed is less than a set speed, the regulation control signal generated increases the first current, and when the current control circuit detects that the turn-on speed is greater than the set speed, the regulation control signal generated decreases the first current, and the reference value characterizes the set speed.

[0007] Optionally, the driving current regulating circuit further includes: a detection signal acquisition circuit connected to the power tube to acquire the detection signal, wherein the detection signal includes at least one of a driving voltage, a drain-source voltage, a slope of the driving voltage and a slope of the drain-source voltage.

[0008] Optionally, the characterization value acquisition circuit obtains the Miller platform maintenance time of the driving voltage of the power tube, the falling time of the drain-source voltage of the power tube, or the absolute value of the falling slope of the drain-source voltage of the power tube according to the detection signal to characterize the turn-on speed.

[0009] Optionally, the characterization value acquisition circuit includes: a charging time control circuit, which receives any of the detection signals, and uses the time consumed from the detection signal reaching the first detection state to the detection signal reaching the second detection state as the charging time; and a charging circuit, which uses the charging voltage value obtained by charging the first capacitor with a first current source during the charging time as the characterization value, wherein different detection signals correspond to different first detection states and second detection states; the current control circuit uses the reference voltage value converted from the set time as a reference value, and when the charging voltage value is greater than the reference voltage value, it represents that the turn-on speed is less than the set speed, and vice versa, it represents that the turn-on speed is greater than the set speed.

[0010] Optionally, the set time varies in a positive correlation with the drain-source voltage during the period when the power tube is completely turned off, so that the turn-on speed remains unchanged.

[0011] Optionally, the characterization value acquisition circuit includes: an operation circuit, which uses the slope of the drain-source voltage of the power tube as the detection signal to obtain the absolute value of the falling slope of the drain-source voltage, and uses it as the characterization value, wherein the current control circuit uses the set reference slope as the reference value, and when the absolute value of the falling slope of the drain-source voltage is greater than the reference slope, it represents that the turn-on speed is greater than the set speed, otherwise it represents that the turn-on speed is less than the set speed.

[0012] Optionally, the current providing circuit includes: a first time period acquisition circuit, which receives any of the detection signals, and takes the moment when the detection signal reaches the first detection state as the starting moment of the first time period, and takes the moment when the detection signal reaches the second detection state as the ending moment of the first time period; a current selection circuit, which provides the first current to the power tube at the starting moment of the first time period, and switches the first current to a second current at the end moment of the first time period, wherein the second current is greater than the first current, and different detection signals correspond to different first detection states and second detection states.

[0013] Optionally, when the detection signal is a driving voltage or a drain-source voltage, the detection signal reaching a first detection state and the detection signal reaching a second detection state correspond to the detection signal reaching different voltage thresholds respectively.

[0014] Optionally, when the detection signal is the slope of the driving voltage or the slope of the drain-source voltage, the detection signal reaching the first detection state and the detection signal reaching the second detection state correspond to the detection signal reaching different slope inflection points respectively.

[0015] Optionally, when the detection signal is the driving voltage, the voltage threshold corresponding to the first detection state reached by the driving voltage is less than the Miller platform voltage, and the voltage threshold corresponding to the second detection state reached by the driving voltage is greater than the Miller platform voltage; when the detection signal is the drain-source voltage, the voltage threshold corresponding to the first detection state reached by the drain-source voltage is not greater than the maximum value of the drain-source voltage, and the voltage threshold corresponding to the second detection state reached by the drain-source voltage is not less than the minimum value of the drain-source voltage.

[0016] Optionally, the driving current regulation circuit includes: a first comparator, wherein the first input terminal and the second input terminal of the first comparator respectively receive the detection signal and the voltage threshold corresponding to the first detection state when the detection signal reaches a first detection state; a second comparator, wherein the first input terminal and the second input terminal of the second comparator respectively receive the detection signal and the voltage threshold corresponding to the second detection state when the detection signal reaches a second detection state; and an RS trigger, wherein the set terminal and the reset terminal of the RS trigger are respectively connected to the output terminal of the first comparator and the output terminal of the second comparator.

[0017] Optionally, the driving current regulation circuit includes: a slope inflection point detection circuit, which, when the slope of the driving voltage or the slope of the drain-source voltage reaches the first slope inflection point and the second slope inflection point in the conduction process of the power tube, corresponds to the moment when the detection signal reaches the first detection state and the moment when the detection signal reaches the second detection state, respectively.

[0018] Optionally, the current selection circuit includes a first branch for providing a third current and a second branch for providing a fourth current, wherein, during the first time period, the current selection circuit provides the first current to the power tube according to the fourth current; at the end of the first time period, the current selection circuit provides the second current to the power tube according to the third current or the sum of the third current and the fourth current.

[0019] Optionally, the current selection circuit also includes a driving circuit, wherein, during the first time period, the current selection circuit converts the fourth current into the first current via the driving circuit and provides it to the power tube; at the end of the first time period, the current selection circuit converts the third current or the sum of the third current and the fourth current into the second current via the driving circuit and provides it to the power tube.

[0020] Optionally, the current control circuit includes: a sampling and holding circuit, connected to the characterization value acquisition circuit, sampling and holding the characterization value to obtain the sampled and held value of the characterization value; a first operational amplifier, the first input terminal and the second input terminal of the first operational amplifier respectively receive the sampled and held value of the characterization value and the reference value, and the output terminal provides the adjustment control signal.

[0021] Optionally, the current control circuit also includes: a second current source and a third transistor connected in series between the power supply terminal and the ground terminal, the control terminal of the third transistor is connected to the output terminal of the first operational amplifier, and the common node of the second current source and the third transistor provides the adjustment control signal.

[0022] Optionally, the current providing circuit includes: a fourth controlled current source, the control end of the fourth controlled current source receives the adjustment control signal, and the output end is used to output the fourth current; a fifth transistor, the fifth transistor is connected in series with the fourth controlled current source; a third current source, used to output the third current; a sixth transistor, the sixth transistor is connected in series with the third current source; wherein the fifth transistor is turned on during the period when the conduction control signal of the power tube is valid, or is turned on within the first time period; and the sixth transistor is turned on during a non-first time period within the period when the conduction control signal is valid.

[0023] Optionally, the drain end of the power tube is connected to the source end of the gallium nitride transistor, the source end of the power tube is grounded, the control end of the gallium nitride transistor is grounded, and the gallium nitride transistor is a depletion-type transistor.

[0024] According to another aspect of the present invention, a method for regulating a driving current of a power tube is provided, comprising: providing a first current to the power tube within a first time period after the power tube is turned on; obtaining a characterization value characterizing a turn-on speed of the power tube according to a detection signal of the power tube; generating a regulation control signal according to the characterization value and a reference value to adjust the magnitude of the first current so as to adjust the magnitude of the driving current of the power tube, wherein when it is detected that the turn-on speed is less than a set speed, the regulation control signal generated increases the first current, and when it is detected that the turn-on speed is greater than the set speed, the regulation control signal generated decreases the first current, and the reference value characterizes the set speed.

[0025] The beneficial effects of the present invention include at least:

[0026] The driving current regulating circuit and driving current regulating method of the power tube provided by the present invention apply a first current with a smaller current value to the power tube in the first time period after the power tube is turned on through the current supply circuit, and apply a second current with a larger current value to the power tube after the first time period, so as to provide a smaller driving current to the power tube during the Miller platform maintenance time of the power tube, so as to preliminarily reduce the falling slope of the drain-source voltage of the power tube. In addition, a current control circuit is provided, which can adjust the current in the first time period according to the acquired characterization value and the reference value of the turn-on speed. That is, the size of the driving current in the Miller platform maintenance time is dynamically adjusted according to the speed of the detected turn-on speed, and closed-loop control is realized, so that the turn-on speed of the power tube is constantly close to the set speed, and the dynamic control of the turn-on speed of the power tube is realized, radiation is reduced, and electromagnetic compatibility is optimized. Moreover, since the driving current can be dynamically adjusted, it can be adapted to different types of power tubes.

[0027] Furthermore, the characterization value acquisition circuit acquires the Miller platform maintenance time of the driving voltage, the falling time of the drain-source voltage of the power tube, or the absolute value of the falling slope of the drain-source voltage according to the detection signal to characterize the turn-on speed. Specifically, the charging time control circuit uses the time consumed from the detection signal reaching the first detection state to the detection signal reaching the second detection state as the charging time, and the charging time can characterize the Miller platform maintenance time or the falling time of the drain-source voltage. Then, the charging voltage of the capacitor during the charging time is used as the characterization value of the turn-on speed, or the absolute value of the falling slope of the drain-source voltage of the power tube calculated by the operation circuit is used as the characterization value. The magnitude of the first current can be adjusted by comparing the characterization value and the reference value. Therefore, the magnitude of the driving current can be accurately adjusted according to the speed of the power tube turn-on, and the adjustment accuracy is high. The circuit forms that can be used are diverse, with a wide range of applications and low cost.

[0028] Furthermore, the above-mentioned drive current regulation circuit can be used to regulate the drive current of different types of power tubes in different switching power supplies and power converters, without the need to set additional off-chip pins to regulate the drive current, and the circuit has strong adaptability.

[0029] It should be noted that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1a A schematic diagram of a conventional power tube driving current regulating circuit is shown;

[0031] Figure 1b Shows Figure 1a A schematic diagram of waveforms of some signals of a current regulating circuit;

[0032] Figure 2 A schematic block diagram of a driving current regulating circuit of a power tube according to an embodiment of the present invention is shown;

[0033] Figure 3 Shows Figure 2 A schematic circuit diagram of a first time period acquisition circuit in a driving current regulating circuit;

[0034] Figure 4 A schematic circuit diagram of a driving current regulating circuit of a power tube according to a first embodiment of the present invention is shown;

[0035] Figure 5 Shows Figure 4 A schematic waveform diagram of each signal in a driving current regulating circuit of a power tube;

[0036] Figure 6 A schematic circuit diagram of a driving current regulating circuit of a power tube according to a second embodiment of the present invention is shown;

[0037] Figure 7 A schematic circuit diagram of a driving current regulating circuit of a power tube according to a third embodiment of the present invention is shown;

[0038] Figure 8 A schematic circuit diagram of a driving current regulating circuit of a power tube according to a fourth embodiment of the present invention is shown;

[0039] Fig. 9 Shows Figure 8 A schematic waveform diagram of each signal in a driving current regulating circuit of a power tube;

[0040] Fig.10 A schematic circuit diagram of a driving current regulating circuit of a power tube according to a fifth embodiment of the present invention is shown;

[0041] Fig.11 A schematic flow chart of a method for regulating a driving current of a power tube according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0043] Figure 2 A schematic block diagram of a driving current regulating circuit of a power tube according to an embodiment of the present invention is shown; Figure 3 Shows Figure 2 A schematic circuit diagram of a first time period acquisition circuit in a driving current regulation circuit.

[0044] like Figure 2 As shown, the present invention provides a driving current regulating circuit suitable for a power tube of a switching power supply. The driving current regulating circuit 100 of this embodiment is used to provide a driving current and a driving voltage for the power tube of the switching power supply, and can adjust the magnitude of the driving current. The power tube is generally a main power tube in a power converter.

[0045] The driving current regulating circuit 100 of this embodiment includes a current supply circuit 120, a characterization value acquisition circuit 130 and a current control circuit 140. The current supply circuit 120 provides a first current I1 to the power tube Q0 in a first time period after the power tube Q0 is turned on. The characterization value acquisition circuit 130 acquires a characterization value characterizing the turn-on speed of the power tube according to the detection signal of the power tube. The current control circuit 140 generates an adjustment control signal Vctrl according to the characterization value and the reference value to adjust the magnitude of the first current generated by the current supply circuit 120 to adjust the driving current of the power tube Q0. The reference value here represents the set speed. Then, when the current control circuit 140 detects that the turn-on speed is less than the set speed according to the characterization value and the reference value, the adjustment control signal Vctrl generated increases the first current. Conversely, when the current control circuit 140 detects that the turn-on speed is greater than the set speed according to the characterization value and the reference value, the adjustment control signal Vctrl generated decreases the first current. That is, by detecting the speed of the opening, the magnitude of the first current in the first time period T1 representing the maintenance time of the Miller platform is closed-loop adjusted, thereby adjusting the magnitude of the driving current of the power tube Q0, controlling its opening speed, and optimizing electromagnetic compatibility. Optionally, the current providing circuit 120 is also used to provide a second current I2 to the power tube Q0 in a second time period starting from the end of the first time period, and the second current I2 is greater than the first current I1.

[0046] Furthermore, the drive current control circuit 100 also includes a detection signal acquisition circuit 110, which is connected to the power tube Q0 to obtain a detection signal. The detection signal acquisition circuit 110 may further include a sampling circuit and a slope detection circuit (not shown in the figure), the sampling circuit acquires the drive voltage Gate and the drain-source voltage Vds from the power tube Q0, and the slope detection circuit acquires the slope of the drive voltage and the slope of the drain-source voltage. Thus, the detection signal acquisition circuit 110 can output at least one detection signal, that is, at least one of the drive voltage Gate, the drain-source voltage Vds, the slope of the drive voltage, and the slope dvdt of the drain-source voltage.

[0047] In this embodiment, the current providing circuit 120 includes a first time period acquisition circuit 122 and a current selection circuit 121. The first time period acquisition circuit 122 receives any detection signal, takes the moment when the detection signal reaches the first detection state as the starting moment of the first time period, outputs the starting moment mark signal Son of the first time period, takes the moment when the detection signal reaches the second detection state as the ending moment of the first time period, and outputs the ending moment mark signal Soff of the first time period. Here, different detection signals correspond to different first detection states and second detection states, so the first time period acquisition circuit can include different circuit structures, corresponding to different detection signals respectively. The current selection circuit 121 provides the first current to the power tube at the starting moment of the first time period, and switches the first current to the second current at the end moment of the first time period. That is, the current selection circuit 121 performs current switching according to the first time period provided by the first time period acquisition circuit 122. The current control circuit 140 outputs the adjustment control signal Vctrl to adjust the magnitude of the first current generated by the current selection circuit 121.

[0048] Further, the characterization value acquisition circuit 130 obtains the Miller platform maintenance time of the driving voltage of the power tube, the falling time of the drain-source voltage of the power tube, or the absolute value of the falling slope of the drain-source voltage of the power tube according to the detection signal to characterize the turn-on speed. For example, the Miller platform maintenance time of the driving voltage can be obtained according to the driving voltage Gate or the slope of the driving voltage, or the falling time of the drain-source voltage can be obtained according to the drain-source voltage Vds or the slope dvdt of the drain-source voltage, or the absolute value of the falling slope of the drain-source voltage can be obtained according to the slope of the drain-source voltage. Then, the characterization value is obtained according to the obtained Miller platform maintenance time of the driving voltage, the falling time of the drain-source voltage of the power tube, or the absolute value of the falling slope of the drain-source voltage of the power tube. Correspondingly, the characterization value acquisition circuit 130 can also include different circuit structures to obtain different characterization values ​​according to different detection signals.

[0049] Specifically, in one embodiment, the characterization value acquisition circuit 130 may include an operation circuit (not shown in the figure), and the operation circuit uses the slope of the drain-source voltage of the power tube as a detection signal to obtain the absolute value of the falling slope of the drain-source voltage, and uses it as the characterization value. At this time, the current control circuit 140 uses the set reference slope as a reference value, and generates an adjustment control signal Vctrl according to the reference value and the characterization value. Among them, when the absolute value of the falling slope of the drain-source voltage is greater than the reference slope, the characterization turn-on speed is greater than the set speed, and the first current needs to be reduced to reduce the turn-on speed of the power tube. On the contrary, when the absolute value of the falling slope of the drain-source voltage is less than the reference slope, the characterization turn-on speed is less than the set speed, and the first current needs to be increased to increase the turn-on speed of the power tube.

[0050] In another embodiment, the characterization value acquisition circuit 130 may include a charging time control circuit and a charging circuit. The charging time control circuit is used to receive any detection signal, and the time consumed from the detection signal reaching the first detection state to the detection signal reaching the second detection state is used as the charging time. The charging circuit uses the charging voltage value obtained by charging the first capacitor with the first current source during the charging time as the characterization value. The charging time obtained by the charging time control circuit can also characterize the above-mentioned Miller platform maintenance time or the drain-source voltage drop time. When the detection signal is the driving voltage Gate or the slope of the driving voltage, the charging time characterizes the Miller platform maintenance time of the driving voltage. When the detection signal is the drain-source voltage Vds or the slope dvdt of the drain-source voltage, the charging time characterizes the drop time of the drain-source voltage. At this time, the current control circuit 140 uses the reference voltage value obtained by setting the time conversion as the reference value, and provides the adjustment control signal Vctrl according to the reference value and the characterization value. When the charging voltage value is greater than the reference voltage value, it indicates that the turn-on speed is less than the set speed, and the first current needs to be increased; conversely, when the charging voltage value is less than the reference voltage value, it indicates that the turn-on speed is greater than the set speed, and the first current needs to be reduced. In a preferred embodiment, the set time can be positively correlated with the drain-source voltage during the period when the power tube is completely turned off, that is, different set times are set under different drain-source voltages, and the current control circuit 140 will receive different reference values, thereby dynamically adjusting the size of the control signal Vctrl, and then adjusting the size of the first current, so that the turn-on speed of the power tube remains unchanged.

[0051] In other embodiments, the characterization value acquisition circuit 130 may include an operation circuit, a charging time control circuit, and a charging circuit at the same time, and the corresponding characterization value can be obtained regardless of which detection signal is received to enhance the adaptability of the circuit. In this embodiment, the first time period acquisition circuit 122 can also receive different detection signals according to different circuit structures to obtain the first time period. For example, when the detection signal is the driving voltage Gate or the drain-source voltage Vds, the detection signal reaches the first detection state and the detection signal reaches the second detection state respectively corresponding to the detection signal reaching different voltage thresholds. At this time, the first time period acquisition circuit 122 uses the time consumed between the detection signal changing from one voltage threshold to another voltage threshold as the first time period. When the detection signal is the slope of the driving voltage or the slope of the drain-source voltage, the detection signal reaches the first detection state and the detection signal reaches the second detection state respectively corresponding to the detection signal reaching different slope inflection points. At this time, the first time period acquisition circuit 122 uses the time between the generation moments of two adjacent slope inflection points as the first time period. It can correspond to two or even more different circuit forms.

[0052] like Figure 3As shown, in one embodiment, the first time period acquisition circuit 122 includes a first comparator COM1, a second comparator COM2 and an RS trigger RS1. At this time, the detection signal is a driving voltage Gate or a drain-source voltage Vds, and the first input terminal and the second input terminal of the first comparator COM1 respectively receive the detection signal and the detection signal reaches the voltage threshold corresponding to the first detection state, and the first input terminal and the second input terminal of the second comparator COM2 respectively receive the detection signal and the detection signal reaches the voltage threshold corresponding to the second detection state. The set terminal and the reset terminal of the RS trigger are respectively connected to the output terminal of the first comparator COM1 and the output terminal of the second comparator COM2, and receive the rising edge signal RP. The output terminal and the output inverting terminal of the RS trigger respectively output the start time mark signal Son of the first time period and the end time mark signal Soff of the first time period. Then, when the output terminal of the RS trigger is high (the output inverting terminal is low), it indicates that it is in the first time period. Specifically, when the detection signal is the driving voltage Gate, the voltage threshold corresponding to the first detection state is less than the Miller platform voltage, and the voltage threshold corresponding to the second detection state is greater than the Miller platform voltage; when the detection signal is the drain-source voltage Vds, the voltage threshold corresponding to the first detection state is not greater than the maximum value of the drain-source voltage, and the voltage threshold corresponding to the second detection state is not less than the minimum value of the drain-source voltage.

[0053] In another embodiment, the first time period acquisition circuit 122 includes a slope inflection point detection circuit (not shown in the figure), which is used to receive the slope of the driving voltage or the slope of the drain-source voltage, and when the slope of the driving voltage or the slope of the drain-source voltage reaches the first slope inflection point and the second slope inflection point, corresponding to the moment when the detection signal reaches the first detection state and the moment when the detection signal reaches the second detection state, respectively, the first time period start time mark signal Son and the first time period end time mark signal Soff are output respectively.

[0054] Since the first time period acquisition circuit 122 can acquire the moment when the detection signal reaches the first detection state and the moment when the detection signal reaches the second detection state, and the charging time control circuit is used to acquire the time consumed from the detection signal reaching the first detection state to the detection signal reaching the second detection state, the charging time control circuit can have the same circuit structure as the first time period acquisition circuit 122. That is, the charging time control circuit may include a first comparator, a second comparator and an RS trigger, or the charging time control circuit may include a slope inflection point detection circuit. Different circuit structures are used to process different detection signals. When the charging time control circuit includes a first comparator, a second comparator and an RS trigger, the first input terminal and the second input terminal of the first comparator COM1 respectively receive the detection signal and the voltage threshold corresponding to the detection signal reaching the first detection state, and the first input terminal and the second input terminal of the second comparator COM2 respectively receive the detection signal and the voltage threshold corresponding to the detection signal reaching the second detection state. The set terminal and the reset terminal of the RS trigger are respectively connected to the output terminal of the first comparator COM1 and the output terminal of the second comparator COM2. The output end and the output inverting end of the RS trigger output the starting time mark signal of the charging time and the ending time mark signal of the charging time respectively. When the output end of the RS trigger is at a high level (the output inverting end is at a low level), it indicates that it is within the charging time.

[0055] Furthermore, when the charging time control circuit and the first time period acquisition circuit 122 receive the same detection signal, the charging time control circuit can reuse the first time period acquisition circuit 122, which can save a part of the circuit area. And when multiplexing, when the driving voltage Gate or the slope of the driving voltage is used as the detection signal, the first time period obtained represents the Miller platform maintenance time of the driving voltage, and when the drain-source voltage Vds or the slope of the drain-source voltage is used as the detection signal, the first time period obtained represents the fall time of the drain-source voltage. When the charging time control circuit and the first time period acquisition circuit 122 receive different detection signals, they need to set up a set of such circuits respectively.

[0056] Therefore, the characterization value acquisition circuit 130 may include only the operation circuit, or only the charging time control circuit and the charging circuit, or both. The charging time control circuit may include only two comparators and one RS trigger, or only the slope inflection point detection circuit, or both. Similarly, the first time period acquisition circuit 122 may include only two comparators and one RS trigger, or only the slope inflection point detection circuit, or both. They may be combined in any way. The following combination Figures 4 to 10 The circuit diagrams in the figure provide details on some common examples.

[0057] The driving current regulating circuit 100 of the embodiment of the present invention applies a smaller first current to the power tube Q0 in the first time period T1 representing the Miller platform maintenance time, and applies a larger second current to the power tube Q0 in the second time period T2 after the first time period, thereby reducing the driving current of the power tube Q0 during the Miller platform maintenance time to reduce the turn-on speed of the power tube. In addition, the detection signal of the power tube Q0 is detected to obtain a characterization value of the turn-on speed of the power tube, and the magnitude of the first current in the first time period T1 is closed-loop regulated according to the magnitude of the characterization value and the reference value, so that the driving current of the power tube Q0 in this interval can be accurately controlled according to the detection signal, thereby adjusting the turn-on speed of the power tube and optimizing electromagnetic compatibility.

[0058] Figure 4 A schematic circuit diagram of a driving current regulating circuit for a power tube according to a first embodiment of the present invention is shown.

[0059] Combination Figures 2 to 4 The driving current regulating circuit 100 of this embodiment includes a detection signal acquisition circuit 110, a current providing circuit 120, a characterization value acquisition circuit 130 and a current control circuit 140. The current providing circuit 120 includes a first time period acquisition circuit 122 and a current selection circuit 121. The characterization value acquisition circuit 130 includes a charging time control circuit 131 and a charging circuit 132. The connection mode between each circuit module is the same as Figure 2 The same, no further description. In this embodiment, as an example, the characterization value acquisition circuit 130 acquires the Miller platform maintenance time of the driving voltage according to the detection signal, so as to obtain the characterization value to characterize the opening speed of the power tube. At this time, the detection signal is the driving voltage Gate or the slope of the driving voltage, and the characterization value acquisition circuit 130 includes a charging time control circuit 131 and a charging circuit 132. Taking the detection signal as the driving voltage Gate as an example, the charging time control circuit 131 includes a comparator U1, a comparator U2 and an RS trigger RS1. The detection signal received by the first time period acquisition circuit 122 is also a driving voltage Gate, and the circuit structure adopted by it also includes a first comparator U1, a second comparator U2 and an RS trigger RS1. At this time, the charging time control circuit 131 can reuse the first time period acquisition circuit 122, that is, only one of the two can be set. Of course, two repeated circuit structures can also be set.

[0060] Specifically, the first time period acquisition circuit 122 includes a first comparator U1, a second comparator U2 and an RS trigger. The first input terminal and the second input terminal of the first comparator U1 receive the driving voltage Gate detection signal and the voltage threshold REF1 respectively, and the first input terminal and the second input terminal of the second comparator U2 receive the driving voltage Gate and the voltage threshold REF2 respectively. Here, the first input terminal and the second input terminal are respectively the positive input terminal and the reverse input terminal. The output terminal of the first comparator U1 and the output terminal of the second comparator U2 are respectively connected to the set terminal S and the reset terminal R of the RS trigger. The rising edge RP of the output result of the first comparator U1 makes the set terminal S effective, and the rising edge RP of the output result of the second comparator U2 makes the reset terminal R effective. The output terminal Q and the output inverting terminal Q ̅ of the RS trigger respectively output the start time mark signal Son of the first time period and the end time mark signal Soff of the first time period, both of which are effective at a high level. The time consumed by the driving voltage Gate changing from REF1 to REF2 is taken as the first time period T1. The charging time control circuit 131 is exactly the same as the first time period acquisition circuit 122 or the two are multiplexed. At this time, the charging circuit 132 uses the first time period T1 as the charging time, and uses the voltage value VC obtained by charging the first capacitor C1 with the first current source A1 in the first time period as the characterization value. The charging circuit 132 includes the first current source A1, the first capacitor C1 and the seventh transistor Q7, and the output inverting end of the RS trigger is connected to the control end of the seventh transistor Q7, so that in the first time period T1, the seventh transistor Q7 is turned off, and the first current source A1 charges the first capacitor C1; in other time periods, the seventh transistor Q7 is turned on to discharge the first capacitor C1.

[0061] like Figure 4As shown, in this embodiment, the current selection circuit 121 also includes a driving circuit 1211, which is connected to the control end of the power tube Q0 to provide a driving current for the power tube Q0. The driving circuit 1211 is, for example, a totem pole circuit, and may include a first transistor Q1 and a second transistor Q2 connected in series, and a driving voltage Gate is provided to the control end of the power tube Q0 by a common node of the first transistor Q1 and the second transistor Q2. The first end of the first transistor Q1 is connected to the power supply end and receives the power supply voltage VCC, the second end of the first transistor Q1 is connected to the first end of the second transistor Q2, the second end of the second transistor Q2 is connected to the ground end, and the control end of the second transistor Q2 receives the shutdown control signal Voff. The first end can be regarded as a drain end, and the second end can be regarded as a source end. The first transistor Q1 is turned on after receiving the conduction control signal Von, so that the power tube Q0 is also turned on, so it can be roughly considered that the conduction of the two is synchronous, that is, the conduction control signal of the first transistor Q1 can be equivalent to the conduction control signal of the power tube Q0. The current selection circuit 121 provides a first current and a second current to the control terminal of the first transistor Q1 in a first time period T1 after the first transistor Q1 is turned on and in a second time period T2 starting from the end of the first time period T1, respectively, and the second current is greater than the first current. The first time period T1 may correspond to the time when the power transistor Q0 crosses the Miller platform.

[0062] In this embodiment, the current selection circuit 121 includes two branches, namely, a first branch for providing a third current I3 and a second branch for providing a fourth current I4. The two branches are turned on and off by the switch tube to apply different currents in different time periods. In the first time period, the current selection circuit 121 provides the first current I1 to the power tube Q0 according to the fourth current I4; in the second time period starting at the end of the first time period, the current selection circuit 121 provides the second current I2 to the power tube Q0 according to the third current I3 or the sum of the third current and the fourth current (I3+I4). When the current selection circuit 121 includes a driving circuit 1211, in the first time period, the current selection circuit 121 converts the fourth current I4 into the first current I1 via the driving circuit 1211 and provides it to the power tube Q0; in the second time period starting at the end of the first time period, the current selection circuit 121 converts the third current I3 or the sum of the third current and the fourth current (I3+I4) into the second current I2 via the driving circuit 1211 and provides it to the power tube Q0.

[0063] The current selection circuit 121 specifically includes a first branch consisting of a third current source A3 and a sixth transistor Q6, and a second branch consisting of a fourth controlled current source A4 and a fifth transistor Q5. The first end of the fourth controlled current source A4 is connected to the power supply end and receives the power supply voltage VCC, the second end is connected to the first end of the fifth transistor Q5, the second end of the fifth transistor Q5 is connected to the control end of the first transistor Q1, the control end of the fourth controlled current source A4 receives the adjustment control signal Vctrl, and the fifth transistor Q5 is a switch tube. The first end of the sixth transistor Q6 is connected to the power supply end through the third current source A3, the second end of the sixth transistor Q6 is connected to the control end of the first transistor Q1, and the sixth transistor Q6 is also a switch tube. The fourth controlled current source A4 may include a fourth transistor Q4, and the first end mentioned above can be regarded as a drain end, and the second end can be regarded as a source end. When the fifth transistor Q5 is turned on, the fourth current I4 is provided to the control end of the first transistor Q1, and when the sixth transistor Q6 is turned on, the third current I3 is provided to the control end of the first transistor Q1. When the fifth transistor Q5 and the sixth transistor Q6 are both turned on, the third current I3 and the fourth current I4 are simultaneously provided to the control end of the first transistor Q1. By controlling the on and off of the fifth transistor Q5 and the sixth transistor Q6, different currents can be provided to the control end of the first transistor Q1 in different time periods. The fifth transistor Q5 is turned on during the effective period of the on control signal Von of the power tube, or is turned on in the first time period; the sixth transistor Q6 is turned on in the non-first time period during the effective period of the on control signal Von.

[0064] The control ends of the fifth transistor Q5 and the sixth transistor Q6 can be controlled by a logic circuit, for example, by the first AND gate U3 and the second AND gate U4, respectively. The first input end and the second input end of the first AND gate U3 respectively receive the conduction control signal Von of the first transistor Q1 (or the power tube Q0) and the start time mark signal Son of the first time period, and the output end of the first AND gate U3 is connected to the control end of the fifth transistor Q5. The first input end and the second input end of the second AND gate U4 respectively receive the conduction control signal Von of the first transistor Q1 (or the power tube Q0) and the end time mark signal Soff of the first time period, and the output end of the second AND gate U4 is connected to the control end of the sixth transistor Q6. Thus, the fourth current I4 is applied to the control end of the first transistor Q1 in the first time period T1, thereby providing the first current to the power tube Q0, and the third current I3 is applied to its control end in other time periods (including the second time period) when the first transistor Q1 is turned on, thereby providing the second current to the power tube Q0.

[0065] Further, the current control circuit 140 includes a sampling and holding circuit 141 and a first operational amplifier EA. Since the characterization value acquisition circuit 130 needs to acquire the characterization value according to the detection signal, the current control circuit 140 adjusts the first current according to the calculated characterization value and the reference value. In this process, it may be too late to adjust the current. At this time, the sampling and holding circuit 141 can be used to sample and hold the characterization value, and the sampling and holding result is compared with the reference value in the subsequent switching cycle to generate an adjustment control signal Vctrl. The sampling and holding circuit 141 is connected to the characterization value acquisition circuit 130, and the characterization value is sampled and held to obtain the sampled and held value of the characterization value. The first input terminal and the second input terminal of the first operational amplifier EA receive the characterization value and the reference value respectively, and the output terminal provides the adjustment control signal Vctrl. The above-mentioned first terminal can be regarded as a drain terminal, and the second terminal can be regarded as a source terminal. The first input terminal and the second input terminal of the first operational amplifier EA are, for example, a reverse input terminal and a forward input terminal, respectively. The current control circuit 140 may also include a second current source A2 and a third transistor Q3 connected in series between the power supply terminal and the ground terminal. The first end of the third transistor Q3 is connected to the output end of the second current source A2, the second end is connected to the ground end, and the output end of the first operational amplifier EA1 is connected to the control end of the third transistor Q3. The common node of the second current source A2 and the third transistor Q3 is connected to the control end of the fourth controlled current source A4 to provide the adjustment control signal Vctrl. The fourth controlled current source A4 may include, for example, a fourth transistor Q4, and the first operational amplifier EA adjusts the conduction degree of the third transistor Q3 according to the comparison result of the sampling and holding value of the characterization value and the reference value, thereby adjusting the magnitude of the adjustment control signal Vctrl, and then adjusting the conduction degree of the fourth transistor Q4, and adjusting the magnitude of the fourth current I4, so that the magnitude of the first current I1 provided to the power tube Q0 in the first time period can be adjusted. The characterization value represents the turn-on speed of the power tube, and the reference value represents the setting speed. The voltage VC on the capacitor is used as the characterization value, the voltage value Vtref corresponding to the conversion of the setting time tref is used as the reference value, and the sampling and holding value VC1 of the characterization value is compared with the reference value Vtref to generate the adjustment control signal Vctrl. The set time tref changes in a positive correlation with the drain-source voltage Vds during the period when the power tube is completely turned off, so that the turn-on speed of the power tube Q0 remains unchanged.

[0066] Then, the first time period acquisition circuit 122 controls the working states of the fifth transistor Q5 and the sixth transistor Q6, so that the current selection circuit 121 provides a smaller fourth current I4 to the first transistor Q1 in the first time period T1, so as to provide a smaller first current to the power tube Q0, and provides a larger third current I3 to the first transistor Q1 in the second time period T2 after the first time period T1, so as to provide a larger second current to the power tube Q0. The first operational amplifier EA1 also adjusts the magnitude of the first current in the first time period T1 according to the comparison result.

[0067] In a preferred embodiment, the current providing circuit 120 may further include a clamping circuit 124. When the driving voltage Gate reaches a maximum value, the clamping circuit 124 is also required to adjust the driving current. The clamping circuit 124 is connected between the control terminal of the power tube Q0 and the control terminal of the first transistor Q1. When the driving voltage Gate reaches a set reference voltage, the current at the control terminal of the first transistor Q1 is pulled down to maintain the driving current at a minimum value. Figure 4 , a third resistor R3 is connected between the source terminal and the control terminal of the first transistor Q1, which is used to limit the saturation current of the first transistor Q1. The resistor R3 can also be replaced by other components such as a voltage-stabilizing diode. The clamping circuit 124 specifically includes voltage-dividing resistors R1 and R2, a second operational amplifier EA2 and an eighth transistor Q8. The first resistor R1 and the second resistor R2 are connected in series between the control terminal and the ground terminal of the power tube Q0, and the common node of the two provides a voltage-dividing voltage Vg1. The first input terminal and the second input terminal of the second operational amplifier EA2 receive the voltage-dividing voltage Vg1 and the reference voltage Vref respectively, and generate an effective control signal Vd when the voltage-dividing voltage Vg1 is greater than the reference voltage Vref. The first end of the eighth transistor Q8 is connected to the control terminal of the first transistor Q1, the second end of the eighth transistor Q8 is grounded, and the control terminal of the eighth transistor Q8 is connected to the output terminal of the second operational amplifier EA2. The current of the control terminal of the first transistor Q1 is pulled down according to the control signal Vd to control the size of the driving current.

[0068] Figure 5 Shows Figure 4 Schematic waveform diagram of each signal in the driving current regulation circuit of the power tube.

[0069] Combination Figure 4 and Figure 5, the first transistor Q1 and the second transistor Q2 are alternately turned on. At time t1, the first transistor Q1 is turned on. The time period from the first transistor Q1 being turned on to the detection signal reaching the first detection state is the third time period T3. In the third time period T3, a current is provided to the control end of the first transistor Q1, so that the driving voltage Gate continues to rise. The provided current can be the third current I3, or the fourth current I4, or the sum of the third current I3 and the fourth current I4, or other currents. The current applied to the control end of the first transistor Q1 in the third time period T3 can be synchronized with the current applied in the second time period T2, both of which are the third current I3. Correspondingly, the driving current Ich of the power tube Q0 is the second current I2. Then, starting from time t1, the driving voltage Gate of the power tube Q0 continues to rise. The first detection state is when the driving voltage Gate reaches a voltage threshold REF1 less than the Miller platform voltage. At time t2, the driving voltage Gate reaches the voltage threshold REF1. The moment t2 is taken as the starting moment of the first time period T1, and the fourth current I4 is applied to the control terminal of the first transistor Q1. Correspondingly, the driving current Ich of the power tube Q0 is the first current I1. At the moment t3, the driving voltage Gate reaches the Miller platform voltage. In the time period t3-t4, the driving voltage Gate is maintained at the Miller platform voltage, and the drain-source voltage Vds of the power tube Q0 continuously decreases from the maximum value. During this period, the decreasing slope of Vds is not 0. The second detection state is when the driving voltage Gate reaches the voltage threshold REF2 greater than the Miller platform voltage. At the moment t5, the driving voltage Gate reaches the voltage threshold REF2, which is the end moment of the first time period T1. The time period t2-t5 is taken as the first time period T1, and this time period is used to characterize the Miller platform maintenance time. After the moment t5, the second time period T2 is entered. In the second time period T2, the third current I3 is applied to the control terminal of the first transistor Q1 to provide the second current to the power tube Q0, so that the driving voltage Gate continues to rise. The time period from the end of the first time period T1 to the time when the first transistor Q1 starts to turn off is the second time period T2. At time t6, the driving voltage Gate reaches the maximum value, and the driving current is pulled down by the clamp circuit 124. Then, after time t6, the driving current Ich is pulled down to the minimum value.

[0070] Further, see Figure 5At time t7, the first transistor Q1 is turned off and the second transistor Q2 is turned on. At time t8, the next switching cycle is entered. In the first time period T1 of t2-t5, the charging circuit 132 also charges the first capacitor C1 to obtain the charging voltage VC as the characterization value, and the voltage Vtref is used as the reference value. Then the current control circuit 140 also adjusts the magnitude of the first current according to the comparison result of the sampling and holding value of the characterization value and the reference value. It can be seen that in this embodiment, the maximum value of the charging voltage VC is greater than the voltage Vtref, and it is considered that the Miller platform is maintained for a long time, exceeding the set time, and the first current in the first time period T1 needs to be increased. Since the comparison result of the characterization value and the reference value must be calculated in a switching cycle for current regulation and the current switching must be performed, it may be too late to perform current regulation. At this time, a sampling and holding circuit 141 can be set to sample and hold the result of the charging circuit 132, and perform current regulation in the next switching cycle. Then, at time t9, the first time period T1 of the next switching cycle begins, so that the first current can be increased in the first time period t9-t10, thereby increasing the drive current. The above process can be repeated for each switching cycle thereafter.

[0071] Figure 6 A schematic circuit diagram of a driving current regulating circuit for a power tube according to a second embodiment of the present invention is shown.

[0072] In this embodiment, in order to ensure that the current switching (switching between the first current and the second current) and the current adjustment (adjustment of the first current) in the same switching cycle do not affect each other, the first time period acquisition circuit 122 and the charging time control circuit 131 can receive different detection signals. Figure 4 The structure is the same as shown in FIG. 1 , the received detection signal is the driving voltage Gate, and the charging circuit 132 uses the voltage value on the capacitor during the charging time as the characterization value. However, the detection signal received by the first time period acquisition circuit 122 is the drain-source voltage Vds, and its circuit structure is still the same as FIG. Figure 4 The same, or a slope inflection point detection circuit can also be selected. Thus, the current switching can be performed according to the drain-source voltage Vds, and the magnitude of the first current can be adjusted according to the Miller platform time of the driving voltage. The current switching and current regulation in the same switching cycle do not affect each other.

[0073] Specifically, Figure 6As shown, the driving current regulating circuit 100 of this embodiment also includes a detection signal acquisition circuit 110, a current providing circuit 120, a characterization value acquisition circuit 130 and a current control circuit 140. The current providing circuit 120 includes a first time period acquisition circuit 122 and a current selection circuit 121. The characterization value acquisition circuit 130 includes a charging time control circuit 131 and a charging circuit 132. The circuit elements and connection relationships of each circuit module are the same as those of FIG. Figure 4 The same as the embodiment, the same points will not be repeated. Figure 4 The difference between the embodiments lies in that the detection signal received by the first time period acquisition circuit 122 is different, and the signal received by the control terminal of the fifth transistor Q5 is different.

[0074] See also Figure 6 , the detection signal received by the first time period acquisition circuit 122 is the drain-source voltage Vds of the power tube. Correspondingly, the voltage threshold corresponding to the first detection state is not greater than the maximum value of the drain-source voltage Vds, and the voltage threshold corresponding to the second detection state is not less than the minimum value of the drain-source voltage Vds. At this time, the positive input terminal and the reverse input terminal of the first comparator U1 receive the voltage threshold REF4 and the drain-source voltage Vds respectively, and the positive input terminal and the reverse input terminal of the second comparator U2 receive the voltage threshold REF3 and the drain-source voltage Vds respectively. The voltage threshold REF4 is slightly less than the maximum value of the drain-source voltage Vds, and the voltage threshold REF3 is slightly greater than the minimum value of the drain-source voltage Vds. The time period from when the drain-source voltage Vds is just less than the voltage threshold REF4 to when it is just less than the voltage threshold REF3 is taken as the first time period T1, thereby realizing the switching between the first current and the second current. Correspondingly, the names of the comparator and the RS trigger in the charging time control circuit 131 are replaced by comparator U7, comparator U8 and RS trigger RS2.

[0075] Furthermore, in this embodiment, the control end of the fifth transistor Q5 only receives the turn-on control signal Von of the first transistor Q1. Thus, during the time period when the first transistor Q1 is turned on, the fifth transistor Q5 is always in the on state, and continuously provides the fourth current I4 to the control end of the first transistor Q1. That is, in the third time period T3 when the first transistor Q1 just starts to be turned on, the sum of the third current I3 and the fourth current I4 is processed by the drive circuit 1211 and provided to the control end of the first transistor Q1 as the second current; in the first time period T1, the fourth current I4 is processed by the drive circuit 1211 and provided to the control end of the first transistor Q1 as the first current; in the second time period T2, the sum of the third current I3 and the fourth current I4 is processed by the drive circuit 1211 and provided to the control end of the first transistor Q1 as the second current. The current control circuit 140 is used to adjust the size of the fourth current I4 in the first time period. This embodiment may also be applicable Figure 5 The waveform diagram shown in FIG. Figure 4 The similarities among the embodiments will not be described in detail here.

[0076] Figure 7 A schematic circuit diagram of a driving current regulating circuit for a power tube according to a third embodiment of the present invention is shown.

[0077] like Figure 7 As shown, the driving current regulating circuit 100 of this embodiment also includes a detection signal acquisition circuit 110, a current providing circuit 120, a characterization value acquisition circuit 130 and a current control circuit 140. The current providing circuit 120 includes a first time period acquisition circuit 122 and a current selection circuit 121. The characterization value acquisition circuit 130 includes a charging time control circuit 131 and a charging circuit 132. The circuit elements and connection relationships of each circuit module are similar to Figure 4 The embodiments are the same and similarities will not be repeated here.

[0078] In this embodiment, as an example, the characterization value acquisition circuit 130 acquires the falling time of the drain-source voltage according to the detection signal, thereby obtaining the characterization value to characterize the turn-on speed of the power tube. At this time, the detection signal is the drain-source voltage Vds or the slope of the drain-source voltage, and the characterization value acquisition circuit 130 includes a charging time control circuit 131 and a charging circuit 132. The charging time control circuit 131 includes a comparator U7, a comparator U8 and an RS trigger RS2, and its circuit connection refers to Figure 6 The first time period acquisition circuit 122 is not described here. The first time period acquisition circuit 122 can be Figure 3 Any circuit described in will not be described in detail here.

[0079] Figure 8 FIG. 4 shows a schematic circuit diagram of a driving current regulating circuit of a power tube according to a fourth embodiment of the present invention. Fig. 9 Shows Figure 8 Schematic waveform diagram of each signal in the driving current regulation circuit of the power tube.

[0080] like Figure 8 As shown, the driving current regulating circuit 100 of this embodiment also includes a detection signal acquisition circuit 110, a current providing circuit 120, a characterization value acquisition circuit 130 and a current control circuit 140. The current providing circuit 120 includes a first time period acquisition circuit 122 and a current selection circuit 121. The connection relationship and working principle of each circuit module are similar to Figure 4 The embodiments are the same and will not be described again here.

[0081] In this embodiment, as an example, the characterization value acquisition circuit 130 acquires the absolute value of the falling slope of the drain-source voltage according to the detection signal, so as to obtain the characterization value to characterize the turn-on speed of the power tube. At this time, the detection signal is the slope dvdt of the drain-source voltage, and the characterization value acquisition circuit 130 includes an operation circuit, which is used to obtain the falling slope dvdt1 of the drain-source voltage according to the slope dvdt of the drain-source voltage, and use it as the characterization value. At this time, the set reference slope Vdref is used as the reference value, and the first operational amplifier EA1 compares the sampling and holding value of the falling slope dvdt1 of the drain-source voltage with the reference value to generate an adjustment control signal Vctrl to adjust the magnitude of the first current. When the characterization value dvdt1 is greater than the set reference slope Vdref, it is considered that the turn-on speed is greater than the set speed, and the first current should be reduced; otherwise, the first current should be increased.

[0082] like Figure 8 As shown, as an example, the first time period acquisition circuit 122 of the present embodiment includes a slope inflection point detection circuit for detecting the inflection point of the slope dvdt of the drain-source voltage. Then the detection signal reaches the first detection state and the detection signal reaches the second detection state respectively corresponding to the detection signal reaching two adjacent slope inflection points. Since the drain-source voltage Vds continues to decline in the first time period, its slope is a negative value, so the detection signal can be used as the slope dvdt of the drain-source voltage, and the falling slope dvdt1 of the drain-source voltage can be obtained accordingly, and dvdt1 at this time is a positive value. That is, the slope inflection point detection circuit receives the slope dvdt of the drain-source voltage to obtain the falling slope dvdt1 of the drain-source voltage. In addition, a slope reference value REF5 not less than zero can be set to characterize the slope inflection point, and the falling slope dvdt1 of the drain-source voltage can be compared with it. Specifically, an implementation of the slope inflection point detection circuit includes, for example, a comparator U5 and a NOT gate U6. Then the positive input terminal and the reverse input terminal of the comparator U5 receive the falling slope dvdt1 of the drain-source voltage and the slope reference value REF5 respectively, and the output terminal is connected to the input terminal of the NOT gate (or inverter) U6. Therefore, when the falling slope dvdt1 of the drain-source voltage is greater than the slope reference value REF5, it is considered that the detection signal reaches the first slope inflection point, and the output terminal of the comparator U5 generates the start time mark signal Son of the first time period. When the falling slope dvdt1 of the drain-source voltage is less than the slope reference value REF5, it is considered that the detection signal reaches the second slope inflection point, and the output terminal of the NOT gate U6 generates the end time mark signal Soff of the first time period. Further, since the characterization value acquisition circuit 130 acquires the absolute value dvdt1 of the falling slope of the drain-source voltage according to the detection signal, the slope detection circuit can also be directly connected to the output terminal of the characterization value acquisition circuit 130 to directly acquire the absolute value dvdt1 of the falling slope of the drain-source voltage.

[0083] like Fig. 9As shown, at time t1, the first transistor Q1 starts to conduct, and the third current I3 is applied to its control terminal to provide the second current to the power tube Q0. At time t2, the drain-source voltage Vds starts to decrease, with a decreasing slope. At this time, the decreasing slope dvdt1 of the drain-source voltage begins to be greater than the slope reference value REF5, which is the starting time of the first time period T1, that is, the detection signal reaches the first slope inflection point. At time t3, the decreasing slope dvdt1 of the drain-source voltage begins to be less than REF5, which is the end time of the first time period T1, that is, the detection signal reaches the second slope inflection point. In the first time period, the fourth current I4 is applied to the control terminal of the first transistor Q1 to provide the first current to the power tube Q0. At time t4, the driving current is pulled down by the clamp circuit 124. Since it is detected that the characterization value dvdt1 in the first time period T1 is greater than the reference value Vdref, it is considered that the turn-on speed is greater than the set speed, and the first current should be reduced. In the next switching cycle, the first current I1 is reduced.

[0084] Fig.10 A schematic circuit diagram of a driving current regulating circuit for a power tube according to a sixth embodiment of the present invention is shown.

[0085] like Fig.10 As shown, in some embodiments, the main power tube is a depletion-type transistor, such as a GaN transistor. At this time, the above-mentioned power tube Q0 is connected in the circuit as an auxiliary tube. Specifically, the drain end of the power tube Q0 is connected to the source end of the gallium nitride transistor QS, the source end of the power tube Q0 is grounded, the control end of the gallium nitride transistor QS is grounded, and the gallium nitride transistor is a depletion-type transistor. Then, according to the connection method of the two transistors, the drain-source voltage Vds of the power tube Q0 can represent the gate voltage of the gallium nitride transistor QS, that is, its driving voltage. Adjusting the driving voltage of the power tube Q0 can be equivalent to adjusting the driving voltage of the transistor QS, and its turn-on rate can be controlled. At this time, the current regulation circuit of this embodiment can be used Figure 2 , Figure 4 , Figure 6 , Figure 7 or Figure 8 The current regulating circuit 100 shown in any embodiment includes a detection signal acquisition circuit 110, a current providing circuit 120, a characterization value acquisition circuit 130 and a current control circuit 140. The current providing circuit 120 and the current control circuit 140 can select the circuit of any of the above embodiments, which will not be described in detail here.

[0086] Figures 2 to 10 Only several possible implementation forms of the driving current regulating circuit 100 of the present invention are shown. In other embodiments, other components and circuit modules may be used to form the driving current regulating circuit 100 to achieve the above functions, which are not listed one by one here.

[0087] Fig.11 A schematic flow chart of a method for regulating a driving current of a power tube according to an embodiment of the present invention is shown.

[0088] The present invention provides a method for regulating the driving current of a power tube, which is suitable for the above Figures 2 to 10 The driving current regulating circuit of the power tube shown in the figure includes: The driving current regulating circuit of the power tube includes: The driving current regulating method of this embodiment specifically includes the following steps:

[0089] In step S101, a first current is provided to the power tube within a first time period after the power tube is turned on.

[0090] In step S102, a characterizing value characterizing a turn-on speed of the power tube is obtained according to a detection signal of the power tube.

[0091] In step S103, an adjustment control signal is generated according to the characterization value and the reference value to adjust the magnitude of the first current so as to adjust the magnitude of the driving current of the power tube. The reference value represents the set speed, and when it is detected that the opening speed is less than the set speed, the adjustment control signal generated increases the first current, and when it is detected that the opening speed is greater than the set speed, the adjustment control signal generated decreases the first current.

[0092] The driving current adjustment method of this embodiment is as follows: Figures 2 to 10 The driving current regulating circuit 100 of the power tube described in the embodiment is implemented on the basis. The specific circuit and working principle can be found in the above description and will not be repeated here.

[0093] In summary, the driving current regulating circuit and driving current regulating method of the power tube provided by the present invention apply a first current with a smaller current value to the power tube in the first time period after the power tube is turned on through the current supply circuit, and apply a second current with a larger current value to the power tube in the second time period after the first time period, so as to provide a smaller driving current to the power tube during the Miller platform maintenance time of the power tube, so as to preliminarily reduce the falling slope of the drain-source voltage of the power tube. In addition, a current control circuit is provided, which can adjust the current in the first time period according to the acquired characterization value and reference value of the turn-on speed. That is, the size of the driving current in the Miller platform maintenance time is dynamically adjusted according to the speed of the detected turn-on speed, and closed-loop control is realized, so that the turn-on speed of the power tube is constantly close to the set speed, and the dynamic control of the turn-on speed of the power tube is realized, radiation is reduced, and electromagnetic compatibility is optimized. Moreover, since the driving current can be dynamically adjusted, it can be adapted to different types of power tubes.

[0094] It should be noted that the numerical values ​​in this article are only used for exemplary description. In other embodiments of the present invention, other numerical values ​​can also be sampled to implement this solution. The specific settings should be reasonable according to the actual situation, and the present invention does not limit this.

[0095] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

[0096] It should also be understood that the terms and expressions used herein are for descriptive purposes only, and one or more embodiments of this specification should not be limited to these terms and expressions. The use of these terms and expressions does not mean to exclude any equivalent features of the illustrations and descriptions (or parts thereof), and it should be recognized that various modifications that may exist should also be included in the scope of the claims. Other modifications, changes and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

Claims

1. A driving current regulating circuit for a power tube, comprising: a current supply circuit for supplying a first current to the power tube within a first time period after the power tube is turned on; A characterization value acquisition circuit, which acquires a characterization value characterizing a turn-on speed of the power tube according to a detection signal of the power tube; The current control circuit generates an adjustment control signal according to the characterization value and the reference value to adjust the magnitude of the first current generated by the current providing circuit, so as to adjust the magnitude of the driving current of the power tube. When the current control circuit detects that the opening speed is less than the set speed, the regulating control signal generated causes the first current to increase; when the current control circuit detects that the opening speed is greater than the set speed, the regulating control signal generated causes the first current to decrease; and the reference value represents the set speed.

2. The driving current regulating circuit according to claim 1, further comprising: A detection signal acquisition circuit is connected to the power tube to acquire the detection signal, wherein the detection signal includes at least one of a driving voltage, a drain-source voltage, a slope of the driving voltage, and a slope of the drain-source voltage.

3. The driving current regulating circuit according to claim 1, wherein: The characterization value acquisition circuit obtains the Miller platform maintenance time of the driving voltage of the power tube, the falling time of the drain-source voltage of the power tube, or the absolute value of the falling slope of the drain-source voltage of the power tube according to the detection signal to characterize the turn-on speed.

4. The driving current regulating circuit according to claim 3, wherein: The characterization value acquisition circuit comprises: a charging time control circuit, receiving any of the detection signals, and taking the time from when the detection signal changes from the first detection state to when the detection signal changes from the second detection state as the charging time; and The charging circuit uses a charging voltage value obtained by charging the first capacitor with a first current source during the charging time as the characterization value, Wherein, different detection signals correspond to different first detection states and second detection states; The current control circuit uses the reference voltage value converted from the set time as a reference value. When the charging voltage value is greater than the reference voltage value, it indicates that the opening speed is less than the set speed. Otherwise, it indicates that the opening speed is greater than the set speed.

5. The driving current regulating circuit according to claim 4, wherein: The setting time varies in a positive correlation with the drain-source voltage during the period when the power tube is completely turned off, so that the turn-on speed remains unchanged.

6. The driving current regulating circuit according to claim 3, wherein: The characterization value acquisition circuit comprises: The computing circuit uses the slope of the drain-source voltage of the power tube as the detection signal to obtain the absolute value of the falling slope of the drain-source voltage and uses it as the characterization value. The current control circuit uses a set reference slope as a reference value. When the absolute value of the falling slope of the drain-source voltage is greater than the reference slope, it indicates that the turn-on speed is greater than the set speed. Otherwise, it indicates that the turn-on speed is less than the set speed.

7. The driving current regulating circuit according to claim 1, wherein: The current providing circuit comprises: a first time period acquisition circuit, receiving any of the detection signals, taking the time when the detection signal reaches the first detection state as the start time of the first time period, and taking the time when the detection signal reaches the second detection state as the end time of the first time period; a current selection circuit, which provides the first current to the power tube at the start time of the first time period, and switches the first current to a second current at the end time of the first time period, wherein the second current is greater than the first current, Different detection signals correspond to different first detection states and second detection states.

8. The driving current regulating circuit according to claim 4 or 7, wherein: When the detection signal is a driving voltage or a drain-source voltage, the detection signal reaching a first detection state and the detection signal reaching a second detection state correspond to the detection signal reaching different voltage thresholds respectively.

9. The driving current regulating circuit according to claim 4 or 7, wherein: When the detection signal is the slope of the driving voltage or the slope of the drain-source voltage, the detection signal reaching the first detection state and the detection signal reaching the second detection state correspond to the detection signal reaching different slope inflection points respectively.

10. The driving current regulating circuit according to claim 8, wherein: When the detection signal is the driving voltage, the voltage threshold corresponding to the first detection state reached by the driving voltage is less than the Miller platform voltage, and the voltage threshold corresponding to the second detection state reached by the driving voltage is greater than the Miller platform voltage; when the detection signal is the drain-source voltage, the voltage threshold corresponding to the first detection state reached by the drain-source voltage is not greater than the maximum value of the drain-source voltage, and the voltage threshold corresponding to the second detection state reached by the drain-source voltage is not less than the minimum value of the drain-source voltage.

11. The driving current regulating circuit according to claim 8, wherein: The driving current regulating circuit comprises: A first comparator, wherein a first input terminal and a second input terminal of the first comparator respectively receive the detection signal and a voltage threshold corresponding to the detection signal reaching a first detection state; a second comparator, wherein a first input terminal and a second input terminal of the second comparator respectively receive the detection signal and a voltage threshold corresponding to the detection signal reaching a second detection state; and An RS trigger, wherein a set terminal and a reset terminal of the RS trigger are respectively connected to the output terminal of the first comparator and the output terminal of the second comparator.

12. The driving current regulating circuit according to claim 9, wherein: The driving current regulating circuit comprises: The slope inflection point detection circuit, when the slope of the driving voltage or the slope of the drain-source voltage reaches the first slope inflection point and the second slope inflection point in the conduction process of the power tube, corresponds to the moment when the detection signal reaches the first detection state and the moment when the detection signal reaches the second detection state respectively.

13. The driving current regulating circuit according to claim 7, wherein: The current selection circuit comprises a first branch for providing a third current and a second branch for providing a fourth current, Wherein, during the first time period, the current selection circuit provides the first current to the power tube according to the fourth current; At the end of the first time period, the current selection circuit provides the second current to the power tube according to the third current or the sum of the third current and the fourth current.

14. The driving current regulating circuit according to claim 13, wherein: The current selection circuit also includes a driving circuit, Wherein, during the first time period, the current selection circuit converts the fourth current into the first current via the driving circuit and provides it to the power tube; At the end of the first time period, the current selection circuit converts the third current or the sum of the third current and the fourth current into the second current via the driving circuit and provides the second current to the power tube.

15. The driving current regulating circuit according to claim 1, wherein: The current control circuit comprises: A sampling and holding circuit, connected to the characterization value acquisition circuit, samples and holds the characterization value to obtain a sampled and held value of the characterization value; A first operational amplifier, wherein a first input terminal and a second input terminal of the first operational amplifier receive the sample-and-hold value of the characterization value and the reference value respectively, and an output terminal provides the adjustment control signal.

16. The driving current regulating circuit according to claim 15, wherein: The current control circuit further includes: A second current source and a third transistor are connected in series between a power supply terminal and a ground terminal, a control terminal of the third transistor is connected to an output terminal of the first operational amplifier, and a common node of the second current source and the third transistor provides the regulation control signal.

17. The driving current regulating circuit according to claim 13, wherein: The current providing circuit comprises: a fourth controlled current source, wherein a control terminal of the fourth controlled current source receives the adjustment control signal, and an output terminal of the fourth controlled current source is used to output the fourth current; a fifth transistor, the fifth transistor being connected in series with the fourth controlled current source; A third current source, configured to output the third current; a sixth transistor, the sixth transistor being connected in series with the third current source; The fifth transistor is turned on during the period when the conduction control signal of the power tube is valid, or is turned on during the first time period; the sixth transistor is turned on during the period other than the first time period when the conduction control signal is valid.

18. The driving current regulating circuit according to any one of claims 1 to 7, wherein: The drain end of the power tube is connected to the source end of the gallium nitride transistor, the source end of the power tube is grounded, the control end of the gallium nitride transistor is grounded, and the gallium nitride transistor is a depletion-type transistor.

19. A method for regulating a driving current of a power tube, comprising: Providing a first current to the power tube within a first time period after the power tube is turned on; Acquire a characterization value characterizing a turn-on speed of the power tube according to a detection signal of the power tube; Generate an adjustment control signal according to the characterization value and the reference value to adjust the magnitude of the first current, so as to adjust the magnitude of the driving current of the power tube, When it is detected that the opening speed is less than the set speed, the regulating control signal generated increases the first current; when it is detected that the opening speed is greater than the set speed, the regulating control signal generated decreases the first current; and the reference value represents the set speed.

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