A control method of a switching tube, a driving device and electronic equipment

Abstract

The application relates to a control method of a switching tube, a driving device and electronic equipment, and belongs to the field of electronic circuits. The control method of the switching tube comprises the following steps: providing a multi-stage control strategy, and controlling the switching tube by using the control strategy to reduce the loss of the switching tube; wherein at least one stage in the multi-stage control strategy adopts a control strategy different from a square wave. The application controls the switching tube by dividing the conventional square wave control into a multi-stage control strategy, at least one stage in the multi-stage control strategy adopts a control strategy different from a square wave to reduce the loss of the switching tube, and the effects of reducing the heat generation, prolonging the service life of the switching tube and saving energy are achieved.

Description

Technical Field

[0001] This application belongs to the field of electronic circuits, and specifically relates to a control method, driving device and electronic equipment for a switching transistor. Background Technology

[0002] In power electronic systems, the losses of switching transistors mainly include conduction losses and switching losses. Conduction losses refer to the energy loss caused by the on-resistance of the transistor when it is in the on-state. Switching losses, on the other hand, refer to the energy loss generated during the transient transitions between on and off states. This type of loss is particularly significant in high-frequency switching applications, directly affecting system efficiency and heat generation. Therefore, optimizing the losses of switching transistors can not only save energy but also reduce heat generation and extend the lifespan of the transistors. Summary of the Invention

[0003] Therefore, the purpose of this application is to provide a control method, driving device and electronic device for a switching transistor to reduce the loss of the switching transistor.

[0004] The embodiments of this application are implemented as follows:

[0005] In a first aspect, embodiments of this application provide a control method for a switching transistor, comprising: providing a multi-stage control strategy, and using the control strategy to control the switching transistor to reduce the losses of the switching transistor; wherein, at least one of the multi-stages adopts a control strategy different from that of a square wave.

[0006] In the above embodiments, the switching transistor is controlled by dividing the conventional square wave control into a multi-stage control strategy, and at least one of the stages adopts a different control strategy than the square wave to reduce the loss of the switching transistor, thereby achieving the effects of reducing heat generation, increasing the service life of the switching transistor and saving energy.

[0007] In one possible implementation of the first aspect embodiment, the multi-stage includes an on-state stage, an amplification stage, a saturation stage, and a off-state stage; controlling the switching transistor using the control strategy includes controlling the switching transistor using at least one of the following control strategies: Strategy 1: In the on-state stage, driving the switching transistor with a drive current greater than the starting current of the amplification stage to accelerate the on-state of the switching transistor; Strategy 2: In the amplification stage, driving the switching transistor with a drive current positively correlated with the product of the input current of the switching transistor and the target amplification factor to reduce the drive loss of the switching transistor; Strategy 3: In the saturation stage, increasing the amplification factor of the switching transistor or stopping the power supply to the drive terminal of the switching transistor; Strategy 4: In the off-state stage, turning off the switching transistor with a negative voltage to accelerate the off-state speed of the switching transistor.

[0008] In the above embodiments, at least one control strategy different from the square wave can be used to control the switching transistor to reduce switching losses. If all four stages employ control strategies different from the traditional square wave, the switching transistor losses can be minimized. For example, in the turn-on stage, an increased drive current is used to accelerate the turn-on of the transistor and reduce turn-on losses; in the amplification stage, a smaller amplification factor is used to reduce the drive losses of the transistor; in the saturation stage, the saturation voltage drop between the input and output terminals of the transistor is reduced by increasing the amplification factor or stopping the power supply to the drive terminal of the transistor, thereby reducing the conduction losses of the transistor; in the turn-off stage, the transistor is turned off with a negative voltage to accelerate the turn-off speed and reduce the switching losses of the transistor.

[0009] In one possible implementation of the first aspect embodiment, turning off the switch transistor with negative voltage includes: first stopping the power supply to the drive terminal of the switch transistor, and then pulling down the voltage at the drive terminal of the switch transistor to be lower than the voltage at the output terminal of the switch transistor; or, first pulling up the voltage at the output terminal of the switch transistor, and then discharging the voltage at the drive terminal of the switch transistor.

[0010] In the above embodiments, the above method can accelerate the turn-off speed of the switching transistor, thereby reducing the switching losses of the switching transistor.

[0011] In one possible implementation of the first aspect embodiment, the switching transistor is a composite transistor, which includes a Darlington transistor or an IGBT transistor. Turning off the switching transistor with a negative voltage includes: first discharging the driving terminal voltage of the low-power transistor in the composite transistor, and then discharging the driving terminal voltage of the high-power transistor in the composite transistor; or, first discharging the driving terminal voltage of the low-power transistor in the composite transistor, then raising the output terminal voltage of the high-power transistor in the composite transistor, and then discharging the driving terminal voltage of the high-power transistor.

[0012] In the above embodiments, for Darlington transistors or IGBT transistors, the above method can accelerate the turn-off speed of the switching transistor, thereby reducing the switching losses of the switching transistor.

[0013] In one possible implementation of the first aspect embodiment, during the amplification phase, the target amplification factor is related to the parameters of the switching transistor; and / or, during the saturation phase, the amplification factor of the switching transistor or the time for which power is stopped to the driving terminal of the switching transistor is related to the parameters of the switching transistor; wherein the parameters include at least one of the following: the temperature of the circuit in which the switching transistor is located, the peak current at the input terminal of the switching transistor, and the input voltage of the switching transistor.

[0014] In the above embodiments, the amplification factor in both the amplification and saturation stages is related to the parameters of the switching transistor. Different switching transistor parameters correspond to different amplification factors. The time when the power supply to the drive end stops is also related to the parameters of the switching transistor. By taking into account the parameters of the switching transistor, such as the temperature of the circuit in which the switching transistor is located, the peak current at the input end of the switching transistor, and the input voltage of the switching transistor, the amplification factor or the time when the power supply to the drive end stops can be selected, which is beneficial to further reduce the loss of the switching transistor.

[0015] In one possible implementation of the first aspect embodiment, increasing the amplification factor of the switching transistor during the saturation stage includes: increasing the amplification factor of the switching transistor using any of the following methods: Method 1: simultaneously increasing the input current and the drive current of the switching transistor, wherein the increase in the drive current is less than the increase in the input current; Method 2: increasing the input current of the switching transistor while keeping the drive current of the switching transistor unchanged; Method 3: increasing the input current of the switching transistor while decreasing the drive current of the switching transistor.

[0016] In the above embodiments, any of the above methods can improve the amplification factor of the switching transistor. By increasing the amplification factor of the switching transistor in the saturation stage, the saturation voltage drop between the input and output terminals of the switching transistor can be reduced, thereby reducing the conduction loss of the switching transistor.

[0017] In one possible implementation of the first aspect embodiment, the output terminal of the switching transistor is grounded via a first switch, and the output terminal of the switching transistor is also grounded via a capacitor. A first diode and / or a second switch are also provided between the output terminal of the switching transistor and the capacitor. The method further includes: during the saturation stage, controlling the duration of the first switch being turned off according to the power supply demand of the capacitor, wherein the switching transistor charges the capacitor when the first switch is turned off.

[0018] In the above embodiments, during the saturation stage, the duration of the first switch being turned off is controlled according to the power supply demand of the capacitor, thereby solving the problems of insufficient VCC power supply and / or excessive power supply.

[0019] In one possible implementation of the first aspect embodiment, the output terminal of the switching transistor is also connected to the capacitor via a first diode, and the method further includes: during the shutdown phase, controlling the first switch to turn off and the second switch to turn on, so that the capacitor provides a reverse current from the drive terminal to the output terminal of the switching transistor.

[0020] In the above embodiments, during the shutdown phase, the first switch is turned off and the second switch is turned on, so that the capacitor provides reverse current from the drive end to the output end of the switching transistor, thereby accelerating the extraction of charge from the drive end and improving the shutdown speed.

[0021] In one possible implementation of the first aspect embodiment, the driving terminal of the switching transistor is connected to the current mirror via a second diode or MOSFET. The method further includes: during the saturation stage, when the voltage at the driving terminal of the switching transistor is greater than a preset voltage, gradually increasing the current of the current mirror to reduce the on-state voltage difference of the current mirror.

[0022] In the above embodiments, during the saturation stage, when the driving terminal voltage of the switching transistor is greater than the preset voltage, the current of the current mirror is gradually increased to reduce the on-state voltage difference of the current mirror, thereby improving the driving capability of the switching transistor.

[0023] Secondly, embodiments of this application also provide a switching transistor driving device, including: a switching transistor and a control circuit; the control circuit is connected to the driving terminal of the switching transistor, the control circuit being used to provide a control strategy comprising multiple stages, and using the control strategy to control the switching transistor to reduce the loss of the switching transistor; wherein, at least one of the multiple stages adopts a control strategy different from that of a square wave.

[0024] In one possible implementation of the second aspect embodiment, the control circuit includes: a capacitor, a first switch, and a first diode and / or a second switch. The output terminal of the switch is grounded via the first switch, and the output terminal of the switch is also grounded via the capacitor. A first diode and / or a second switch are further disposed between the output terminal of the switch and the capacitor. The multi-stage includes an on-state stage, an amplification stage, a saturation stage, and a off-state stage. During the on-state stage and the amplification stage, the first switch is turned on. During the off-state stage, the first switch is turned off. During the saturation stage, the on or off state of the first switch is controlled according to the power supply requirements of the capacitor. When the first switch is turned off, the switch is used to charge the capacitor.

[0025] In one possible implementation of the second aspect embodiment, the output terminal of the switching transistor is connected to the capacitor via the second switch; during the shutdown phase, the first switch is in the off state and the second switch is in the on state, and the capacitor provides reverse current from the drive terminal to the output terminal of the switching transistor.

[0026] In one possible implementation of the second aspect embodiment, the control circuit further includes: a third switch, wherein the driving terminal of the switching transistor is also grounded via the third switch; during the closing phase, the third switch is in a conducting state.

[0027] In one possible implementation of the second aspect embodiment, the control circuit includes: a controller and a current mirror, wherein the driving terminal of the switching transistor is connected to the current mirror via a second diode or a MOSFET; during the saturation stage, when the voltage at the driving terminal of the switching transistor is greater than a preset voltage, the controller is used to gradually increase the current of the current mirror to reduce the on-state voltage difference of the current mirror.

[0028] Thirdly, embodiments of this application also provide an electronic device, including: a switching transistor driving device provided as described in the second aspect embodiments and / or in combination with any possible implementation of the second aspect embodiments.

[0029] Other features and advantages of this application will be set forth in the following description. The objectives and other advantages of this application can be realized and obtained through the structures specifically pointed out in the written description and the accompanying drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings. The above and other objects, features, and advantages of this application will become clearer through the accompanying drawings.

[0031] Figure 1 This is the traditional drive waveform for driving the switching transistor in the existing technology.

[0032] Figure 2 A flowchart illustrating a control method for a switching transistor provided in an embodiment of this application is shown.

[0033] Figure 3 A schematic diagram of the structure of a Darlington tube provided in an embodiment of this application is shown.

[0034] Figure 4 The diagram illustrates various current waveforms for driving a single switching transistor according to embodiments of this application.

[0035] Figure 5 A schematic diagram of the current waveform of a driving composite transistor provided in an embodiment of this application is shown.

[0036] Figure 6 A circuit diagram illustrating the first method for optimizing the turn-off time of a single switch provided in an embodiment of this application is shown.

[0037] Figure 7 A circuit diagram illustrating the first optimized composite transistor turn-off time provided in an embodiment of this application is shown.

[0038] Figure 8aA circuit diagram illustrating a second method for optimizing the turn-off time of a single switch provided in an embodiment of this application is shown.

[0039] Figure 8b A circuit diagram illustrating a third method for optimizing the turn-off time of a single switch transistor, as provided in an embodiment of this application, is shown.

[0040] Figure 8c The circuit diagram shown is a fourth example of optimizing the turn-off time of a single switch provided in an embodiment of this application.

[0041] Figure 9 This illustration shows a schematic diagram of a control circuit and a switching transistor connection provided in an embodiment of this application. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following embodiments are provided as examples to more clearly illustrate the technical solutions of this application, and should not be used to limit the scope of protection of this application. Those skilled in the art will understand that, without conflict, the following embodiments and features can be combined with each other.

[0043] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, relational terms such as "first," "second," etc., in the description of this application are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0044] Furthermore, the term "and / or" in this application is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0045] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical term "connection" can be a direct connection or an indirect connection through an intermediate medium.

[0046] To reduce the losses of the switching transistor, embodiments of this application provide a highly efficient control method and driving device for the switching transistor. Using the control method shown in this application, the losses of the switching transistor can be effectively reduced, and the efficiency of the switching transistor can be improved. In contrast, the traditional driving method is... Figure 1 The square wave drive shown uses the same high-level drive during the turn-on, amplification, and saturation stages of the switching transistor, but uses a low-level drive during the turn-off stage, resulting in high conduction and switching losses. In this embodiment, the conventional square wave control is divided into a multi-stage control strategy to control the switching transistor, and at least one of the stages uses a different control strategy than the traditional square wave, thereby reducing the losses of the switching transistor.

[0047] The switching transistors shown in this application may be MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), BJTs (Bipolar Junction Transistors), Darlington transistors, etc.

[0048] The following is combined with Figure 2 The control method shown in this application is described, including steps S1 and S2.

[0049] Step S1: Provide a multi-stage control strategy.

[0050] By dividing conventional square wave control into a multi-stage control strategy, the aforementioned multi-stage includes an on-state stage, an amplification stage, a saturation stage, and an off-state stage, corresponding to the four stages of the switching transistor. At least one stage in the multi-stage (e.g., four stages) employs a control strategy different from that of the square wave.

[0051] In some possible implementations, at least two of the four stages described above may have different control strategies, while the control strategies for the remaining stages may be the same. In other possible implementations, each stage may have a different control strategy. Alternatively, some stages may use the control strategy shown in this application, while others may use conventional control strategies, resulting in at least two stages having different control strategies. For example, at least one of the turn-on, amplification, saturation, and turn-off stages may use the control strategy shown in this application, while the remaining stages may use conventional control strategies.

[0052] Since at least one stage uses a control strategy different from the traditional square wave, the loss of the switching transistor can be reduced. If all four stages use a control strategy different from the traditional square wave, the loss of the switching transistor can be reduced to the maximum extent.

[0053] Step S2: Use a multi-stage control strategy to control the switching transistor to reduce its losses.

[0054] The switching transistor can be controlled using at least one of the following control strategies:

[0055] Strategy 1: During the turn-on phase, accelerate the turn-on of the switching transistor with a larger drive current to reduce turn-on losses. For example, drive the switching transistor with a drive current greater than the starting current of the amplification phase to accelerate the turn-on of the switching transistor.

[0056] Strategy 2: During the amplification stage, a smaller amplification factor is used to reduce the drive loss of the switching transistor, and the drive current of the switching transistor changes with the input current of the switching transistor. For example, the switching transistor is driven with a drive current that is positively correlated with the product of the input current of the switching transistor and the target amplification factor, so as to reduce the drive loss of the switching transistor.

[0057] Strategy 3: During the saturation stage, increase the amplification factor of the switching transistor or stop supplying power to the driving end of the switching transistor to reduce the saturation voltage drop between the input and output ends of the switching transistor, thereby reducing the conduction loss of the switching transistor.

[0058] Strategy 4: During the shutdown phase, the switching transistor is turned off with negative pressure to accelerate the shutdown speed of the switching transistor and thus reduce the switching losses of the switching transistor.

[0059] Different types of switching transistors have different drive terminals, input terminals, and output terminals. For example, taking a bipolar transistor (BJT) as an example, the drive terminal is the base, the input terminal can be the collector, and the output terminal can be the emitter. Furthermore, the input and output terminals of a BJT can be reversed, depending on the type of BJT. Similarly, taking a MOSFET as an example, the drive terminal can be the gate, the input terminal can be the drain, and the output terminal can be the source. Again, the input and output terminals of a MOSFET can be reversed, depending on the type of MOSFET.

[0060] The above four control strategies (strategy 1, strategy 2, strategy 3, and strategy 4) can be used simultaneously or at least one of them. For example, in one possible implementation, a larger drive current can be provided in the turn-on phase to improve efficiency, and then a smaller amplification factor can be used in the amplification phase to reduce the drive loss of the switching transistor. Then, in the saturation phase, the amplification factor of the switching transistor can be increased or the power supply to the drive terminal of the switching transistor can be stopped. Finally, in the turn-off phase, the switching transistor can be turned off by negative voltage to reduce the loss of the switching transistor.

[0061] The switching transistor in this application can be a single switching transistor or a composite transistor, typically a composite transistor containing two or more switching transistors. For example, a composite transistor can include a Darlington transistor or an IGBT transistor, as shown in the schematic diagram below. Figure 3 As shown, a Darlington transistor or IGBT typically contains two switching transistors, such as... Figure 3 The high-power transistor S1 and the low-power transistor S2 are in the middle, and the high-power transistor S1 is driven by the low-power transistor S2.

[0062] When all four strategies described above are employed simultaneously, in one possible implementation, the drive current waveform for a single switching transistor can be as follows: Figure 4 As shown, Figure 4 Four different drive current waveforms are shown: drive current waveform 1, drive current waveform 2, drive current waveform 3, and drive current waveform 4. Each drive current waveform differs in at least one of the following stages: turn-on, amplification, saturation, and turn-off. Figure 4 The diagram only shows the scenario where power is cut off to the drive terminal of the switching transistor during the saturation phase. If the amplification factor of the switching transistor is increased during the saturation phase, the waveform during this phase will be different. Figure 4 Waveform diagram of the intermediate saturation stage. Compared to Figure 1 The driving waveform shown in this application significantly reduces the losses of the switching transistor compared to the conventional driving waveform. Figure 1 By employing the control strategy shown in this application, the corresponding band waveforms during the turn-on, amplification, saturation, and turn-off phases are made consistent with... Figure 1 The waveform shown is different; it is no longer a traditional square wave.

[0063] When all four strategies mentioned above are employed simultaneously, in one possible implementation, the waveform principle for a Darlington transistor or an IGBT transistor is as follows: Figure 5 As shown, Figure 5 The solid line in the middle represents Figure 3 The drive current waveform of the high-power transistor S1 is shown by the dashed line. Figure 3 The drive current waveforms of the small and medium power transistors S2 and S1 are similar in overall shape, but the delays are different, and the waveform amplitude of the small power transistor S2 is smaller than that of the large power transistor S1.

[0064] In the amplification stage, the drive current of the switching transistor can be equal to the product of the input current of the switching transistor and the target amplification factor, and it varies with the input current of the switching transistor. For example, if the input current increases, the drive current increases; if the input current decreases, the drive current decreases. In some possible implementations, the input current can be replaced with the output current. In this case, the drive current can be equal to the product of the output current of the switching transistor and another fixed target amplification factor.

[0065] If the switching transistor is a single transistor, the target amplification factor is less than or equal to 7.5 times; if the switching transistor is a composite transistor, such as a Darlington transistor, the target amplification factor is less than or equal to 56 times. Typically, for a single switching transistor, the amplification factor of a conventionally driven switching transistor is above 7.5 times. In this embodiment, to reduce the driving loss of the switching transistor, an amplification factor less than 7.5 times is used to reduce the driving current. Taking a transistor as an example, in this embodiment, the amplification factor is equal to IC / IB and less than 7.5, where IC represents the collector current of the transistor and IB represents the base current of the transistor.

[0066] In some possible implementations, the target magnification is a single fixed magnification that remains constant throughout different control cycles; in other possible implementations, the target magnification may vary in different control cycles.

[0067] Furthermore, the target amplification factor in the aforementioned amplification stage can be related to the parameters of the switching transistor. These parameters include at least one of the following: the temperature of the circuit in which the switching transistor is located, the instantaneous peak current (IPK) at the input terminal of the switching transistor, and the input voltage of the switching transistor. A pre-established correspondence between different parameters and the target amplification factor can be established. When selecting the target amplification factor later, this correspondence can be used to select the target amplification factor corresponding to the parameter. Different parameters can correspond to different target amplification factors. Generally, the target amplification factor is positively correlated with the aforementioned temperature and input voltage parameters, and negatively correlated with the IPK peak current. Taking an example that simultaneously includes temperature, IPK peak current, and input voltage, generally: the lower the temperature, the lower the input voltage, and the larger the IPK peak current, the smaller the target amplification factor.

[0068] During the saturation phase, the amplification factor of the switching transistor can be increased, or the power supply to the driving terminal of the switching transistor can be stopped. In some possible implementations, during the saturation phase, the amplification factor of the switching transistor or the time for stopping the power supply to the driving terminal of the switching transistor (which can be considered as the proportion of the saturation phase time) is also related to the parameters of the switching transistor. Different parameters result in different amplification factors, or different parameters correspond to different times for stopping the power supply to the driving terminal of the switching transistor. Generally, the amplification factor is positively correlated with the aforementioned temperature and input voltage parameters, and negatively correlated with the IPK peak current. The time for stopping the power supply to the driving terminal is positively correlated with the aforementioned temperature and input voltage parameters, and negatively correlated with the IPK peak current. For example, the lower the temperature, the lower the input voltage, and the larger the IPK peak current, the shorter the time for stopping the power supply to the driving terminal, i.e., the proportion of the saturation phase time is reduced. A correspondence between different parameters and the time for stopping the power supply to the driving terminal can be established in advance, and when selecting the time for stopping the power supply to the driving terminal later, the corresponding time for stopping the power supply to the driving terminal can be selected based on this correspondence.

[0069] Increasing the amplification factor of the switching transistor during the saturation phase can include using any of the following methods:

[0070] Method 1: Simultaneously increase the input current and drive current of the switching transistor, with the increase in drive current being less than the increase in input current.

[0071] Method 2: Increase the input current of the switching transistor while keeping the drive current of the switching transistor unchanged.

[0072] Method 3: Increase the input current of the switching transistor and decrease the drive current of the switching transistor.

[0073] During the shutdown phase, when the switching transistor is turned off with a negative voltage, the process includes: first, stopping the power supply to the driving terminal of the switching transistor, and then pulling the voltage at the driving terminal of the switching transistor down to a level lower than the output voltage of the switching transistor. Taking a transistor as an example, this means first stopping the power supply to the base of the switching transistor, and then pulling the base voltage down to a level lower than the emitter voltage of the switching transistor. The greater the drop in the driving terminal voltage, the faster the switching transistor shuts down. In one possible implementation, the driving terminal of the switching transistor can be grounded through a first switch. During the shutdown phase, the driving terminal voltage can be pulled down by turning on this switch.

[0074] During the shutdown phase, when the switching transistor is turned off with a negative voltage, the process includes: first, pulling up the output voltage of the switching transistor, and then discharging the driving voltage of the switching transistor. Taking a transistor as an example, the emitter voltage of the switching transistor is pulled up first, and then the base voltage of the switching transistor is discharged.

[0075] In one possible implementation, the driving terminal of the switching transistor can be connected via a third switch (such as...). Figure 6 The switch S4 in the middle is grounded, and the output terminal of the switching transistor is connected to the first switch (such as...). Figure 6 The circuit diagram is as follows: Switch S3 is grounded. Figure 6 As shown, Figure 6 In this configuration, the base of the transistor is grounded through switch S4, and the emitter is grounded through switch S3. During the shutdown phase, the emitter voltage can be pulled high by turning off switch S3, and then the base voltage can be discharged by turning on switch S4. Figure 6 In the following diagrams, only transistors are used as examples of switching transistors. Therefore, the use of transistors as switching transistors should not be interpreted as a limitation of this application.

[0076] If the switching transistor is a composite transistor, for example, a composite transistor can include a Darlington transistor or an IGBT transistor. If the switching transistor is... Figure 3The structure shown includes the following process when the switching transistor is turned off with a negative voltage: first, the driving terminal voltage of the small power transistor S2 in the composite transistor is discharged, and then the driving terminal voltage of the large power transistor S1 in the composite transistor is discharged; or, first, the driving terminal voltage of the small power transistor S2 in the composite transistor is discharged, then the output terminal voltage of the large power transistor S1 in the composite transistor is pulled up, and then the driving terminal voltage of the large power transistor S1 is discharged.

[0077] In one possible implementation, the driving terminal of the switching transistor can be connected via a third switch (such as...). Figure 7 Switches S4 and S5 in the circuit are grounded, and the output of the switching transistor is also connected to the first switch (e.g., ...). Figure 7 The circuit diagram is as follows: Switch S3 is grounded. Figure 7 As shown, during the shutdown phase, switch S5 can be turned on first to discharge the driving voltage of the low-power transistor S2, then switch S3 can be turned off to pull up the output voltage of the high-power transistor S1 in the composite transistor, and then switch S4 can be turned on to discharge the driving voltage of the high-power transistor S1.

[0078] In some possible implementations, the output terminal of the switching transistor can also be grounded via the capacitor VCC. Furthermore, a first diode and / or a second switch can be connected in series between the output terminal of the switching transistor and the capacitor. For example, the output terminal of the switching transistor is connected to the capacitor via the first diode, or the output terminal of the switching transistor is connected to the capacitor via a first diode and a second switch connected in parallel. A specific schematic diagram is shown below. Figure 8a , Figure 8b , Figure 8c As shown. Figure 8a In the diagram, the emitter of the switching transistor S1 is connected to the capacitor through the first diode (i.e., diode D1 in the figure). Figure 8b In the diagram, the emitter of the switching transistor S1 is connected to the capacitor via a second switch (i.e., switch S6 in the figure). Figure 8c In this embodiment, the emitter of the switching transistor S1 is connected to the capacitor via a diode D1 and a switch S6 connected in parallel. In this implementation, the control method further includes: during the saturation phase, controlling the duration of switch S3's off-state according to the capacitor's power supply demand, wherein when switch S3 is off, the switching transistor S1 charges the capacitor. When charging the capacitor, for... Figure 8b When switch S3 is off, switch S6 is on; for Figure 8c When switch S3 is off, switch S6 is in the off state. By charging the capacitor during the saturation phase, the capacitor discharges through the switch S1 during the off phase, providing reverse current from the drive terminal to the output terminal of the switch S1.

[0079] The charging process can be divided into the following stages based on the capacitor's power demand: Stage 1: When the capacitor's power demand is insufficient, it is powered with the maximum amount of charge, or with an amount greater than the capacitor's energy consumption. Stage 2: When the capacitor's power demand is excessive, it is powered with an amount less than the capacitor's energy consumption, thus resolving the issues of insufficient and / or excessive VCC power supply. The first switch, in addition to accelerating the closing speed, is also used to supply power to the capacitor's VCC, addressing the issues of insufficient and / or excessive VCC power supply. By controlling the duration of the first switch's on / off state, charging control at different stages can be achieved; for example, when the power demand is insufficient, the duration of the first switch's off state can be extended or advanced.

[0080] During the shutdown phase, power supply to the drive terminal of the switching transistor is stopped. At this time, the capacitor discharges to the switching transistor, providing reverse current from the drive terminal to the output terminal. If the output terminal of the switching transistor is also connected to the capacitor through a first diode and a second switch in parallel (see schematic diagram...), Figure 8c (as shown in the diagram), or, the output of the switching transistor is connected to the capacitor via a second switch (as shown in the schematic diagram). Figure 8b As shown in the figure, the above control method also includes: during the shutdown phase, controlling the second switch (i.e., switch S6) to be turned on and the first switch (i.e., switch S3) to be turned off, so that the capacitor provides the reverse current from the drive end to the output end of the switching transistor, accelerates the extraction of charge from the B-terminal (base), and improves the shutdown speed.

[0081] In some possible implementations, such as Figure 9 As shown, the driving terminal of the switching transistor is connected to a second diode (such as...). Figure 9 The diode D2) or MOSFET (which can be used to...) Figure 9 The diode D2 is replaced with a MOSFET and connected to the current mirror (including MOSFETs S7 and S8, and the reference current source Iref). In this case, the control method further includes: during the saturation stage, when the driving terminal voltage of the switching transistor is greater than a preset voltage (configurable), gradually increasing the current in the current mirror to reduce the on-state voltage difference of the current mirror. For example, when the VB voltage (i.e., the base voltage) is higher than a certain voltage, the reference current Iref in the current mirror can be gradually increased according to the increase in the VB voltage to reduce the on-state voltage difference of MOSFET S8, and / or... Figure 9 The diode D2 in the circuit is replaced with a MOSFET to reduce the on-state voltage difference and improve the driving capability.

[0082] The principle is as follows: When the drive current is large, the voltage difference across the entire loop is very high. For example, driving a 2A IC current, with a 5x amplification, requires a 0.4A drive current. If the internal resistance of switch S3 is 0.3Ω, the required drive voltage is: 0.72V for the on-state voltage difference of switch S3 + 3V for the VBE voltage of switch S1 + 0.8V for the voltage difference of diode D2 + 1V for the voltage difference of MOSFET S8 = 5.52V. However, the power supply range of capacitor VCC is typically 3.3~5V, resulting in insufficient drive capability. The conventional approach is to increase the area of ​​switch S1 and reduce the VBE voltage (the voltage difference between the base and emitter), but this is too costly. This application increases the drive voltage difference of MOSFET S8 by increasing the reference current Iref of the current mirror, thereby reducing the on-state resistance of MOSFET S8 and its on-state voltage difference, thus increasing the drive capability. Replacing diode D2 with a MOSFET follows the same principle.

[0083] in, Figure 9 The current mirror (including MOSFET S7, MOSFET S8, and reference current source Iref), diode D2, diode D1, capacitor VCC, switch S4, and switch S3 are electronic components of the control circuit. In addition, the control circuit may also include controllers.

[0084] The first switch, second switch, and third switch mentioned above can be switching transistors, such as transistor switches or MOSFET switches. In addition, the first switch, second switch, and third switch mentioned above can also be other intelligent switches, such as relays.

[0085] To better understand the effect of the control method shown in this application compared to conventional square wave control, an example is provided below. Assuming a conventional transistor with an 8x amplification factor, an IPK current of 1A, and a conduction time of 3S, the required driving charge is: (1A / 8x) × 3S / 2 = 0.1875 coulombs. If the driving method of this application is used, assuming the power supply is turned off at the 2 / 3 position (which can be earlier or later), the conduction time is 2S. Even with an amplification factor of 5x (which can be smaller), the driving IPK current is (1A × 2 / 3) / 5 = 0.133A, and the required driving charge is: 0.133A × 2S / 2 = 0.133 coulombs. It can be seen that the driving charge of the driving method shown in this application is reduced by 30% compared to the full-drive method. Due to the reduced driving charge, the corresponding driving voltage is also reduced. Simultaneously, the reduced amplification factor also reduces the on-state voltage drop. By accelerating the shutdown method, the shutdown time of conventional VCE (the voltage difference between collector C and emitter E) needs to be more than 120 ns, while the shutdown time is shortened to less than 100 ns by this solution, thus reducing switching losses.

[0086] This application embodiment also provides a switching transistor driving device, which includes a switching transistor and a control circuit. The control circuit is connected to the driving terminal of the switching transistor and is used to provide a multi-stage control strategy and use the control strategy to control the switching transistor to reduce the switching transistor's losses. At least two of the multi-stage stages correspond to different control strategies.

[0087] In some possible implementations, the control circuit includes: a capacitor, a first switch, and a first diode and / or a second switch, the schematic diagram of which is described above. Figure 8a , Figure 8b , Figure 8c The output terminal of the switching transistor is grounded via a first switch, and the output terminal of the switching transistor is also grounded via a capacitor. A first diode and / or a second switch are also provided between the output terminal of the switching transistor and the capacitor. During the turn-on and amplification phases, the first switch is turned on; during the turn-off phase, the first switch is turned off; and during the saturation phase, the first switch is turned on or off according to the power supply requirements of the capacitor. When the first switch is off, the switching transistor is used to charge the capacitor.

[0088] In some possible implementations, if the output of the switching transistor is connected to the capacitor via a first switch, the schematic diagram is as described above. Figure 8b , Figure 8c During the shutdown phase, the first switch is in the off state and the second switch is in the on state. The capacitor provides reverse current from the drive terminal to the output terminal of the switching transistor.

[0089] In some possible implementations, the control circuit also includes a third switch (such as...). Figure 8a , Figure 8b , Figure 8c The drive terminal of the switching transistor (S4) is also grounded via a third switch. During the off phase, the third switch is in the ON state. In the remaining states, the third switch is in the OFF state.

[0090] In some possible implementations, the control circuit further includes: a controller and a current mirror (containing...) Figure 9 The MOSFETs S7 and S8, and the reference current source Iref are in the current mirror. The driving terminal of the switching transistor is connected to the current mirror through diode D2 or MOSFET. In the saturation stage, when the driving terminal voltage of the switching transistor is greater than the preset voltage, the controller is used to gradually increase the current of the current mirror to reduce the on-state voltage difference of the current mirror.

[0091] The connection schematic of the control circuit and the switching transistor can be found in [reference needed]. Figure 9 As shown, Figure 9 The current mirror (including MOSFET S7, MOSFET S8, and reference current source Iref), diode D2, diode D1, capacitor VCC, switch S4, and switch S3 are all electronic components of the control circuit.

[0092] In addition, the controller is also used to control the on or off of the first switch (such as switch S3), the second switch (such as switch S6), and the third switch (such as switch S4 and switch S5), and to adjust the current of the current mirror.

[0093] The controller may be an integrated circuit chip with signal processing capabilities. The aforementioned controller can be a processor, which can be a general-purpose processor, including a Central Processing Unit (CPU), Network Processor (NP), Graphics Processing Unit (GPU), Accelerated Processing Unit (ACCU), Multimedia Application Processor (MAP), microprocessor, etc.; it can also be a Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. Alternatively, the controller can also be any conventional processor.

[0094] The switching transistor driving device provided in this application embodiment can be applied to various switching circuits to realize the turn-off or turn-on control of the switching transistor. For example, it can be applied to various converters, such as flyback converters. The switching transistor driving device provided in this application embodiment has the same implementation principle and technical effect as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the switching transistor driving device embodiment can be referred to the corresponding content in the aforementioned method embodiment.

[0095] This application also provides an electronic device, which may be an electronic device including the above-mentioned switching transistor driving device. For example, the electronic device may be a mobile phone, tablet, computer and other electronic devices.

[0096] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0097] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0098] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0099] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for a switching transistor, characterized in that, include: A multi-stage control strategy is provided, and the control strategy is used to control the switching transistor to reduce the loss of the switching transistor; Among these multiple stages, at least one stage employs a control strategy different from that of the square wave. The multi-stage includes an amplification stage, a saturation stage, and a shutdown stage; the control strategy used to control the switching transistor includes: During the amplification stage, the switching transistor is driven by a drive current that is positively correlated with the product of the input current of the switching transistor and the target amplification factor, so as to reduce the drive loss of the switching transistor. During the saturation stage, the amplification factor of the switching transistor is increased, or the power supply to the driving terminal of the switching transistor is stopped; During the shutdown phase, the switching transistor is shut off with negative pressure to accelerate the shutdown speed of the switching transistor.

2. The control method according to claim 1, characterized in that, The multi-stage process also includes an activation stage; Controlling the switching transistor using the aforementioned control strategy further includes: During the turn-on phase, the switching transistor is driven with a drive current greater than the starting current of the amplification phase to accelerate the turn-on of the switching transistor.

3. The control method according to claim 2, characterized in that, Turning off the switching transistor with negative pressure includes: First, stop supplying power to the driving terminal of the switching transistor, then pull the voltage at the driving terminal of the switching transistor down to a level lower than the output voltage of the switching transistor; or, First, pull up the output voltage of the switching transistor, and then discharge the driving voltage of the switching transistor.

4. The control method according to claim 2, characterized in that, The switching transistor is a composite transistor, including a Darlington transistor or an IGBT transistor, which is used to turn off the switching transistor with negative pressure, including: First, discharge the driving terminal voltage of the low-power transistor in the composite transistor, and then discharge the driving terminal voltage of the high-power transistor in the composite transistor; or, First, the driving terminal voltage of the low-power transistor in the composite transistor is discharged, then the output terminal voltage of the high-power transistor in the composite transistor is raised, and then the driving terminal voltage of the high-power transistor is discharged again.

5. The control method according to claim 2, characterized in that, During the amplification phase, the target amplification factor is related to the parameters of the switching transistor; and / or, during the saturation phase, the amplification factor of the switching transistor or the time for which power is stopped to the drive terminal of the switching transistor is related to the parameters of the switching transistor. The parameters include at least one of the following: the temperature of the circuit in which the switch is located, the peak current at the input terminal of the switch, and the input voltage of the switch.

6. The control method according to claim 2, characterized in that, Increasing the amplification factor of the switching transistor during the saturation phase includes: increasing the amplification factor of the switching transistor using any of the following methods: Method 1: Simultaneously increase the input current and the drive current of the switching transistor, with the increase in drive current being less than the increase in input current; Method 2: Increase the input current of the switching transistor while keeping the drive current of the switching transistor unchanged; Method 3: Increase the input current of the switching transistor and decrease the drive current of the switching transistor.

7. The control method according to claim 2, characterized in that, The output terminal of the switching transistor is grounded via a first switch, and the output terminal of the switching transistor is also grounded via a capacitor. A first diode and / or a second switch are further disposed between the output terminal of the switching transistor and the capacitor; the method further includes: During the saturation phase, the duration of the first switch being turned off is controlled according to the power supply requirements of the capacitor, wherein the switching transistor charges the capacitor when the first switch is turned off.

8. The control method according to claim 7, characterized in that, The output terminal of the switching transistor is connected to the capacitor via a second switch, and the method further includes: During the shutdown phase, the first switch is turned off and the second switch is turned on, so that the capacitor provides reverse current from the drive terminal to the output terminal of the switching transistor.

9. The control method according to claim 2, characterized in that, The driving terminal of the switching transistor is connected to the current mirror via a second diode or MOSFET, and the method further includes: During the saturation stage, when the voltage at the drive terminal of the switching transistor is greater than a preset voltage, the current of the current mirror is gradually increased to reduce the on-state voltage difference of the current mirror.

10. A switching transistor driving device, characterized in that, include: Switching transistor; A control circuit is connected to the drive terminal of the switching transistor. The control circuit is used to provide a multi-stage control strategy and use the control strategy to control the switching transistor to reduce the loss of the switching transistor. Among these multiple stages, at least one stage employs a control strategy different from that of the square wave. The multi-stage includes an amplification stage, a saturation stage, and a shutdown stage; the control strategy used to control the switching transistor includes: During the amplification stage, the switching transistor is driven by a drive current that is positively correlated with the product of the input current of the switching transistor and the target amplification factor, so as to reduce the drive loss of the switching transistor. During the saturation stage, the amplification factor of the switching transistor is increased, or the power supply to the driving terminal of the switching transistor is stopped; During the shutdown phase, the switching transistor is shut off with negative pressure to accelerate the shutdown speed of the switching transistor.

11. The switching transistor driving device according to claim 10, characterized in that, The control circuit includes: a capacitor, a first switch, a first diode and / or a second switch, the output terminal of the switch is grounded through the first switch, the output terminal of the switch is also grounded through the capacitor, and a first diode and / or a second switch are provided between the output terminal of the switch and the capacitor; The multi-stage process also includes an activation stage; During the opening phase and the amplification phase, the first switch is turned on; during the closing phase, the first switch is turned off; and during the saturation phase, the first switch is turned on or off according to the power supply requirements of the capacitor. When the first switch is turned off, the switching transistor is used to charge the capacitor.

12. The switching transistor driving device according to claim 11, characterized in that, The output terminal of the switching transistor is connected to the capacitor via a second switch; During the shutdown phase, the first switch is in the off state and the second switch is in the on state, and the capacitor provides reverse current from the drive terminal to the output terminal of the switching transistor.

13. The switching transistor driving device according to claim 11, characterized in that, The control circuit further includes a third switch, and the driving terminal of the switching transistor is also grounded via the third switch; During the closing phase, the third switch is in the conducting state.

14. The switching transistor drive device according to any one of claims 11-13, characterized in that, The control circuit includes a controller and a current mirror, wherein the driving terminal of the switching transistor is connected to the current mirror through a second diode or a MOSFET; During the saturation stage, when the voltage at the drive terminal of the switching transistor is greater than a preset voltage, the controller gradually increases the current of the current mirror to reduce the on-state voltage difference of the current mirror.

15. An electronic device, characterized in that, include: The switching transistor drive device as described in any one of claims 10-14.

Images