Protection circuit of power switch, power switch and power module
By setting up clamp modules inside and outside the driver chip to form a release loop, the problem of mis-activated and damaged modules during the shutdown of SiC power devices is solved, effectively suppressing the gate voltage and improving the system robustness.
Patent Information
- Application Number
- CN202323341721.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-08
- Publication Date
- 2025-01-17
- Estimated Expiration
- 2033-12-08
AI Technical Summary
SiC power devices have the risk of mis-activated and damaging the module later in the shutdown process. It is mainly due to the increase in the gate voltage of Miller capacitor voltage, which is difficult to effectively suppress the gate voltage.
The internal clamp module is set inside the driver chip and the external clamp module is set outside. Both work at the same time. The driver chip generates a driving signal during the shutdown process and triggers the at least one clamp module to be turned on, forming a drain loop to suppress Gate voltage rises.
It effectively reduces the risk of mis-activated SiC power switch during the shutdown process, and suppresses the gate oscillation amplitude, improves system robustness, and avoids module damage.
Smart Images
Figure CN222366193U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power electronics, in particular to a protection circuit of a power switch, a power switch and a power module. Background Art
[0002] SiC power devices are semiconductor devices made of silicon carbide (SiC) materials. Due to their excellent physical properties, such as high bandgap width, high saturated electron drift velocity, high breakdown strength, low dielectric constant and high thermal conductivity, SiC power devices have significant advantages in high temperature, high frequency and high power applications.
[0003] In SiC power module applications, when the SiC power tube is in the late stage of the shutdown process, its Miller capacitor voltage rises, and the gate is charged through the Miller capacitor, causing the gate voltage to rise or oscillate, posing a risk of mis-starting and damaging the module. A solution is urgently needed to solve the risk of mis-starting and damaging the module when the SiC power tube is in the late stage of the shutdown process. Utility Model Content
[0004] In view of the shortcomings of the prior art described above, the purpose of the utility model is to provide a protection circuit for a power switch, a power switch and a power module. By setting an internal clamping module with a Miller clamping function inside a driver chip, and providing an external Miller clamping module arranged outside the driver chip, the two parts work simultaneously, thereby improving the robustness of the system, reducing the risk of erroneous opening of the power switch, and suppressing the gate oscillation amplitude of the power switch during the switching process.
[0005] In order to achieve the above-mentioned purpose and other related purposes, the technical solution provided by the utility model is as follows:
[0006] A first aspect of an embodiment of the present application provides a protection circuit for a power switch, the protection circuit comprising an internal clamping module, an external clamping module and a driving chip, the internal clamping module being arranged inside the driving chip, and the external clamping module being arranged outside the driving chip; a first end of the internal clamping module is connected to a power switch control end of the power switch through a first end of the driving chip, a second end of the internal clamping module is connected to a negative terminal, and a control end of the internal clamping module is connected to a driving signal generating module of the driving chip; a control end of the external clamping module is connected to a second end of the driving chip, and the external clamping module is connected to a negative terminal. A first end of the internal clamping module is connected to the power switch control end, a second end of the external clamping module is connected to the negative terminal, and a second end of the driving chip is connected to the driving signal generating module; the driving chip is used to collect the power switch control end voltage of the power switch during the shutdown process of the power switch, and generate a driving signal based on the power switch control end voltage and a preset voltage threshold through the driving signal generating module; if the power switch control end voltage is less than the preset voltage threshold, the driving signal triggers at least one of the internal clamping module and the external clamping module to conduct, so as to form at least one discharge loop.
[0007] In some embodiments of the present application, the external clamping module includes a resistor, a capacitor and a first switch tube, the first end of the resistor is connected to the second end of the driving chip, the second end of the resistor is respectively connected to the control end of the first switch tube and the first end of the capacitor, the first end of the first switch tube is connected to the power switch control end, and the second end of the first switch tube is respectively connected to the negative terminal and the second end of the capacitor.
[0008] In some embodiments of the present application, the internal clamping module is a second switch tube, the control end of the second switch tube is connected to the drive signal generating module for receiving the drive signal, the first end of the second switch tube is connected to the power switch control end through the first end of the drive chip, and the second end of the second switch tube is connected to the negative terminal.
[0009] In some embodiments of the present application, the first end of the power switch is connected to an electrical device.
[0010] In some embodiments of the present application, the driver chip also includes a state detection module for detecting the working state of the power switch, and the state detection module is connected to the power switch; when the power switch is in the on state, the internal clamping module and the external clamping module are triggered to disconnect; when the power switch is in the off process, the driver chip is triggered to collect the power switch control terminal voltage of the power switch, and the drive signal generation module is triggered to generate a drive signal based on the power switch control terminal voltage and a preset voltage threshold.
[0011] In some embodiments of the present application, the power switch is a SiC power switch.
[0012] In some embodiments of the present application, a distance between the first end of the external clamp module and the control end of the power switch is less than a preset distance threshold.
[0013] In some embodiments of the present application, the negative terminal is a reference ground of the driving circuit.
[0014] A second aspect of an embodiment of the present application provides a power switch with a protection circuit, comprising a power switch and a protection circuit of the power switch as described in any one of the embodiments of the first aspect above, wherein a power switch control terminal of the power switch is connected to the protection circuit, a first terminal of the power switch is connected to an electrical device, and a second terminal of the power switch is connected to a negative terminal.
[0015] A third aspect of an embodiment of the present application provides a power module, which includes an electrical device, a power switch, and a protection circuit for the power switch as described in any one of the embodiments of the first aspect above, wherein a power switch control terminal of the power switch is connected to the protection circuit, a first terminal of the power switch is connected to the electrical device, and a second terminal of the power switch is connected to a negative terminal.
[0016] As described above, the protection circuit of the power switch, the power switch and the power module of the utility model have at least the following beneficial effects:
[0017] Based on setting an internal clamping module inside the driver chip and an external clamping module outside the driver chip, the driver chip controls at least one of the internal clamping module and the external clamping module to be turned on during the shutdown process of the power switch to form at least one discharge loop, which can effectively avoid the risk of mis-opening and damaging the module when the power switch including the SiC power tube is in the late stage of the shutdown process. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 The utility model is a structural schematic diagram of a protection circuit of a power switch provided by the utility model.
[0019] Figure 2 It is a structural schematic diagram of another protection circuit of a power switch provided by the utility model.
[0020] Figure 3 It is a structural schematic diagram of another protection circuit of a power switch provided by the utility model.
[0021] Figure 4 It is a schematic diagram of a discharge circuit provided by the utility model.
[0022] Figure 5 It is a structural schematic diagram of another protection circuit of a power switch provided by the utility model.
[0023] Figure 6 It is a structural schematic diagram of a specific protection circuit of a power switch provided by the utility model.
[0024] Figure 7 It is a structural schematic diagram of another specific protection circuit of a power switch provided by the utility model.
[0025] Description of Reference Numerals
[0026] Driver IC 110, SiC power switch 120, internal Miller clamp circuit 130, external Miller clamp circuit 140, internal clamp module 310, external clamp module 320, driver chip 330, drive signal generating module 340, power switch 350, first terminal A of the driver chip, second terminal B of the driver chip, negative terminal C, electrical device 360, resistor R, capacitor C, first switch tube T1, and second switch tube T2. DETAILED DESCRIPTION
[0027] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0028] It should be noted that the diagrams provided in the present embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, so the diagrams only show the components related to the present invention rather than the number, shape and size of the components in the actual implementation. The type, quantity and proportion of each component in the actual implementation can be changed at will, and the layout of the components may be more complicated. The structure, proportion, size, etc. shown in the diagrams attached to this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effect and purpose that the present invention can produce.
[0029] As mentioned in the background technology above, the inventors have found that although the negative impact of the Miller effect has been discovered in the application of silicon carbide power modules, and some measures have been taken in related technologies to suppress the negative impact of the Miller effect, there is still a problem that the driving signal is easily interfered with, resulting in a high risk of false turn-on of the SiC power module, or the parasitic inductance increases due to long wiring, resulting in a poor Miller clamping effect.
[0030] Based on this, the utility model proposes a protection circuit for a power switch: by setting an internal clamping module with a Miller clamping function inside a driver chip, and providing an external Miller clamping module set outside the driver chip, the two parts work simultaneously, thereby improving the robustness of the system, reducing the risk of false opening of the power switch, and suppressing the gate oscillation amplitude of the power switch during the switching process.
[0031] In the application process of SiC power switch, the larger switch tube dv / dt will charge the gate through the Miller capacitor, causing the gate voltage to rise or oscillate, which may lead to the risk of false opening and damage to the module. In order to suppress the influence of the Miller effect, a Miller clamp circuit can be used for protection. When the switch tube is turned off, the Miller clamp circuit will reliably pull down the gate.
[0032] See also Figure 1 , Figure 1 This is a schematic diagram of the structure of a protection circuit of a power switch provided by the utility model, such as Figure 1As shown, an internal Miller clamp circuit 130 is provided inside a driver chip Driver IC 110. The driver chip Driver IC 110 and the first end of the internal Miller clamp circuit 130 are connected to the control end (gate) of the SiC power switch 120 through an IAMC (Internal Active Miller Clamp) pin. The control end of the internal Miller clamp circuit 130 receives a driving signal from the driver chip Driver IC 110 to suppress the influence of the Miller capacitor voltage rise on the gate of the SiC power switch 120 when it is in the late stage of the shutdown process. However, the simple internal Miller clamp circuit has a poor Miller clamping effect due to the increase of line parasitic inductance due to the long PCB routing.
[0033] See also Figure 2 , Figure 2 Schematic diagram of another power switch protection circuit provided by the utility model. Figure 2 As shown, an external Miller clamp circuit 140 is provided outside the driver chip Driver IC 110, and is connected to the driver chip Driver IC 110 through an EAMC (External Active Miller Clamp) pin to suppress the influence of the Miller capacitor voltage rise on the gate of the SiC power switch 120 when it is in the late stage of the shutdown process. The external Miller clamp circuit requires the driver chip to output the gate drive signal of the external Miller clamp circuit switch tube. The signal loop is long and easily interfered, resulting in malfunction of the external Miller clamp circuit switch tube.
[0034] Figure 1 and Figure 2 Only the location of the Miller clamp circuit and the connection between it and the power switch are shown. It should be noted that one end of the power switch is also connected to the electrical equipment, and the other end of the power switch and one end of the Miller clamp circuit (internal Miller clamp circuit, external Miller clamp circuit) are also connected to the negative terminal (such as ground, etc.), and the control end of the internal Miller clamp circuit is used to receive the drive signal generated by the drive chip.
[0035] See also Figure 3 , Figure 3 Schematic diagram of another power switch protection circuit provided by the utility model. Figure 3 As shown, the utility model provides a protection circuit for a power switch, which includes an internal clamping module 310, an external clamping module 320 and a driving chip 330, wherein the internal clamping module 310 is arranged inside the driving chip 330, and the external clamping module 320 is arranged outside the driving chip 330.
[0036] The first end of the internal clamp module 310 is connected to the power switch control end of the power switch 350 through the first end A of the driving chip 330, the second end of the internal clamp module 310 is connected to the negative terminal C, and the control end of the internal clamp module 310 is connected to the driving signal generating module 340 of the driving chip 330;
[0037] The control end of the external clamp module 320 is connected to the second end B of the driving chip 330, the first end of the external clamp module 320 is connected to the power switch control end, the second end of the external clamp module 320 is connected to the negative terminal C, and the second end B of the driving chip 330 is connected to the driving signal generating module 340;
[0038] The driver chip 330 is used to collect the voltage of the power switch control terminal of the power switch 350 during the shutdown process of the power switch 350, and generate a driving signal based on the voltage of the power switch control terminal and a preset voltage threshold through the driving signal generation module 340. If the voltage of the power switch control terminal is less than the preset voltage threshold, the driving signal triggers at least one of the internal clamping module 310 and the external clamping module 320 to conduct, so as to form at least one discharge loop. The preset voltage threshold can be configured through the register of the driver chip, and is selected according to the actual debugging effect of those skilled in the art, and is not limited here.
[0039] The first terminal A of the driver chip 330 can be understood as Figure 1 The second terminal B of the driver chip 330 can be understood as Figure 2 EAMC pin in.
[0040] See also Figure 4 , Figure 4 This is a schematic diagram of the discharge circuit provided by the utility model. In order to make the picture clear, Figure 4 The drive signal generation module is omitted, such as Figure 4As shown, when the power switch is in the late stage of the shutdown process, the voltage of its Miller capacitor rises, and the coupled displacement current will charge the gate capacitor of the power switch through the current loop Loop3, causing the gate voltage to rise again, which will cause the power switch to be turned on by mistake in severe cases. The working state of the power switch is detected by the driver chip, and the driver chip generates a drive signal during the shutdown process of the power switch to enable the external clamping module to turn it on, forming a discharge loop Loop2, and suppressing the gate voltage of the power switch from rising. However, as analyzed in the above embodiment, its drive signal is susceptible to interference. At this time, in order to further reduce the accident of mis-turning on the power switch, the drive signal generated by the driver chip during the shutdown process of the power switch can be used to enable the internal clamping module to turn it on, forming a discharge loop Loop1, and suppressing the gate voltage of the power switch from rising. When the enable signal (drive signal) of the external clamping module is interfered with and cannot be guaranteed to be turned on, it can still effectively suppress the gate rise of the power switch to avoid mis-turning on the power switch. The simultaneous use of the internal clamping module and the external clamping module can improve the robustness of the system, reduce the risk of false turn-on of the power switch, and suppress the gate oscillation amplitude during the switching process of the power switch.
[0041] It can be seen that in the protection circuit of the power switch provided in this embodiment, the internal clamping module and the external clamping module can be used separately or in combination, and those skilled in the art can configure the working states of the two modules as needed. Due to the different settings of the internal clamping module and the external clamping module, when they are in the working state at the same time, there may be differences in the conduction time, and it is not required that they must be turned on at the same time.
[0042] In one embodiment, the drive signal generation module includes a generation submodule and a switching submodule, one end of the generation submodule is connected to the first end of the switching submodule, the other end of the generation submodule is connected to the first end of the driver chip, the second end of the switching submodule is connected to the internal clamping module, and the third end of the switching submodule is connected to the external clamping module through the second end of the driver chip. The generation submodule generates a drive signal based on the voltage of the power switch control terminal and the preset voltage threshold, and the switching submodule switches the connection state of the internal clamping module and the external clamping module with the generation submodule. When the connection state is connected, the drive signal can be received, otherwise, when the connection state is cut, the drive signal cannot be received and will not be turned on. The switching submodule can adjust whether the internal clamping module and the external clamping module are in a working state. For example, the drive signal generation module can be implemented by one or more module sets in the driver chip.
[0043] In one embodiment, the driver chip also includes a state detection module for detecting the working state of the power switch, and the state detection module is connected to the power switch; when the power switch is in the on state, the internal clamping module and the external clamping module are triggered to disconnect; when the power switch is in the off process, the driver chip is triggered to collect the power switch control terminal voltage of the power switch, and the drive signal generation module is triggered to generate a drive signal based on the power switch control terminal voltage and a preset voltage threshold.
[0044] The state detection module can be implemented by referring to the relevant functions of the existing driver chip, or by other methods known to those skilled in the art, which is not limited here. The state detection module can be connected to the power switch in a manner that reuses the first end of the driver chip, and can use other pins of the driver chip, which is not limited here.
[0045] It should be noted that, in the above embodiments, the first end of the driver chip may be one or more pins, and those skilled in the art may set them as needed.
[0046] In one embodiment, the first terminal of the power switch is connected to the electrical device.
[0047] In another embodiment, the negative terminal can also be the reference ground of the driving circuit, that is, the power ground of the driving power supply. Taking the inverter product as an example, the negative terminal can be the high voltage source ground of the external input, or it can be the three-phase output. When the driving power supply has only positive voltage supply, the second end of the internal clamping module and the second end of the external clamping module will be connected to the power ground of the driving power supply. If the driving power supply has both positive voltage supply and negative voltage supply, the second end of the internal clamping module and the second end of the external clamping module will be connected to the driving negative voltage, and then to the driving power ground through the driving negative voltage. The second end of the power switch is connected to the driving power ground of the driving power supply.
[0048] See also Figure 5 , Figure 5 Schematic diagram of another power switch protection circuit provided by the utility model. Figure 5 As shown, Figure 3 The difference is that, on the one hand, the negative terminal is grounded. On the other hand, the first end of the power switch is connected to the electrical device 360, which can be one or more electrical devices in various scenarios in which the power switch is applied by those skilled in the art, and is not limited here.
[0049] In one embodiment, the distance between the first end of the external clamping module and the control end of the power switch is less than a preset distance threshold. The preset distance threshold may be a value set by a person skilled in the art as required. For example, the external clamping module may be as close as possible to the gate (control end) of the power switch during PCB Layout, which can effectively reduce the parasitic inductance of the circuit, and the impedance of the discharge loop is low, thereby reducing the gate oscillation of the power switch. However, in this manner, the external clamping module is susceptible to interference when receiving a driving signal. If it can cooperate with the internal clamping module, the safety and reliability of the power switch can be further ensured. In one embodiment, the distance between the first end of the external clamping module and the control end of the power switch can be determined by the line length between the two. If the line length is less than the preset length threshold, it is considered to be a suitable position.
[0050] In one embodiment, the power switch is a power switch such as a SiC power switch that has a Miller effect during a turn-off process.
[0051] In one embodiment, the external clamping module includes a resistor, a capacitor and a first switch tube, the first end of the resistor is connected to the second end of the driving chip, the second end of the resistor is respectively connected to the control end of the first switch tube and the first end of the capacitor, the first end of the first switch tube is connected to the power switch control end, and the second end of the first switch tube is respectively connected to the negative terminal and the second end of the capacitor.
[0052] In one embodiment, the internal clamping module is a second switch tube, the control end of the second switch tube is connected to the drive signal generating module for receiving the drive signal, the first end of the second switch tube is connected to the power switch control end through the first end of the drive chip, and the second end of the second switch tube is connected to the negative terminal.
[0053] For example, the power switch is a SiC power switch, the internal clamping module is the second switch tube, and the external clamping module includes a resistor, a capacitor, and the first switch tube. Figure 6 , Figure 6 This is a schematic diagram of a specific power switch protection circuit provided by the utility model. Figure 6As shown, the driver chip Driver IC is internally provided with a second switch tube T2 as an internal clamp circuit IAMC, and the driver chip Driver IC is externally provided with an external clamp circuit EAMC formed by a resistor R, a capacitor C and a first switch tube T1, and the power switch is a SiC power switch Switch, the first end of the resistor R is connected to the second end B of the driver chip, the second end of the resistor R is respectively connected to the control end of the first switch tube T1 and the first end of the capacitor C, the first end of the first switch tube T1 is connected to the power switch control end of the power switch Switch, and the second end of the first switch tube T1 is respectively connected to the negative terminal and the second end of the capacitor C. The control end of the second switch tube T2 is connected to the drive signal generation module of the driver chip Driver IC for receiving the drive signal, the first end of the second switch tube T2 is connected to the power switch control end of the power switch Switch through the first end of the driver chip Driver IC, and the second end of the second switch tube T2 is connected to the negative terminal. The negative terminal is not shown in this figure.
[0054] For example, the power switch is a SiC power switch, the internal clamping module is the second switch tube, and the external clamping module includes a resistor, a capacitor, and the first switch tube. Figure 7 , Figure 7 : is a schematic diagram of another specific power switch protection circuit provided by the utility model, such as Figure 7As shown in the figure, based on the driver chip with Miller clamp function, an external Miller clamp circuit is designed, and the internal Miller clamp circuit (internal Miller clamp module) and the external Miller clamp circuit (internal Miller clamp module) work simultaneously. When the power tube Switch is in the late stage of the shutdown process, the voltage of its Miller capacitor Crss rises, and the coupled displacement current ICrss will charge the gate capacitor Cgs of the Switch through the current loop Loop3, causing the gate voltage to rise again, and in severe cases, it will cause the Switch to be turned on by mistake. The driver chip EAMC enable signal S1 of the external Miller clamp circuit is enabled when the Switch is in the late stage of the shutdown process, driving the switch tube T1 to turn on, forming a discharge loop Loop2, and suppressing the rise of the Switch gate voltage; in PCB Layout, it can be as close to the gate of the Switch as possible, which can effectively reduce the parasitic inductance of the circuit, and the impedance of the discharge loop is low, reducing the gate oscillation of the Switch, but its S1 signal is susceptible to interference. The switch tube T2 of the internal Miller clamp circuit is inside the driver chip. When the Switch is in the late stage of the shutdown process, a discharge loop Loop1 is formed to suppress the rise of the Switch gate voltage. When the external Miller clamp circuit enable signal S1 is interfered with and T1 cannot be turned on, it can still effectively suppress the rise of the Switch gate to avoid the Switch from being turned on incorrectly. The simultaneous use of the internal Miller clamp circuit and the external Miller clamp circuit can improve the robustness of the system, reduce the risk of the power module being turned on incorrectly, and suppress the gate oscillation amplitude during the power module switching process. Continue to see Figure 7When the internal clamping module (second switch tube T2) is used alone, when the primary input of the driver chip Driver IC receives the shutdown instruction for the power switch Switch, the secondary output will discharge the gate of the power switch Switch (i.e., the power switch control terminal) to achieve shutdown. During the discharge process, the gate voltage of the power switch will begin to decrease. At this time, the internal clamping module inside the IAMC pin, i.e., the second switch tube T2, will be turned on, thereby quickly clamping the gate voltage of the power module to the negative voltage of the driving power supply or ground. When the external clamping module is used alone, similar to the above method, since the IAMC pin is only used to detect the gate voltage of the power switch, when the gate voltage drops to a certain threshold, the internal clamping module inside the IAMC pin will not be turned on, but the EAMC pin will output a high level to the external clamping module, i.e., the first switch tube T1, and turn on the first switch tube T1, thereby quickly clamping the gate voltage of the power module to the negative voltage of the driving power supply or ground. When the internal clamp module and the external clamp module are used at the same time, the IAMC pin will detect the gate voltage of the power switch. When the gate voltage drops to a certain threshold, the internal clamp module inside the IAMC pin will be turned on, and the EAMC pin will output a high level to turn on the external clamp module. The internal clamp module and the external clamp module will work together to quickly clamp the gate voltage of the power switch to the negative voltage of the driving power supply or ground.
[0055] Therefore, the protection circuit of the power switch of the utility model is provided with an internal clamping module and an external clamping module at the same time. During the shutdown process of the power switch, at least one of the internal clamping module and the external clamping module is turned on to form at least one discharge loop, which can avoid the mis-conduction of the power switch. When the internal clamping module and the external clamping module are used at the same time, both can be turned on. Compared with the conduction of a single internal clamping module or an external clamping module, a better clamping effect can be achieved to reliably pull down the gate of the power switch and suppress the gate oscillation amplitude during the switching process of the power switch. In addition, the internal clamping module can still work when the switch tube drive signal of the external clamping module is interfered with, and the reliability of the gate (control end) of the power switch is pulled down. The use of a single external clamping module can be reduced, and the risk of mis-opening of the power switch caused by interference with the switch tube gate drive signal in the external clamping module can be reduced, thereby improving the robustness of the system.
[0056] In addition, the utility model also provides a power switch with a protection circuit, which includes a power switch and the protection circuit of the power switch, wherein the power switch control terminal of the power switch is connected to the protection circuit, the first terminal of the power switch is connected to the electrical device, and the second terminal of the power switch is connected to the negative terminal. By adding a protection circuit to an ordinary power switch, it is possible to avoid mis-conduction of the power switch during the shutdown process.
[0057] In addition, the utility model also provides a power module, which includes an electrical device, a power switch and a protection circuit of the power switch, wherein the power switch control terminal of the power switch is connected to the protection circuit, the first terminal of the power switch is connected to the electrical device, and the second terminal of the power switch is connected to the negative terminal. By adding a protection circuit to an ordinary power switch, it is possible to avoid mis-conduction of the power switch during the shutdown process, further ensuring the safety of the use of the electrical device.
[0058] In summary, in the protection circuit, power switch and power module of the power switch provided by the utility model, based on setting an internal clamping module inside the driver chip and setting an external clamping module outside the driver chip, the driver chip controls at least one of the internal clamping module and the external clamping module to be turned on during the shutdown process of the power switch to form at least one discharge loop, which can effectively avoid the risk of mis-opening and damaging the module when the power switch including the SiC power tube is in the late stage of the shutdown process. The internal clamping module and the external clamping module support simultaneous application and can both be turned on. Compared with the conduction of a single internal clamping module or an external clamping module, a better clamping effect can be achieved to reliably pull down the gate of the power switch and suppress the gate oscillation amplitude during the switching process of the power switch. It can also reduce the use of a single external clamping module, the risk of mis-opening of the power switch caused by interference with the gate drive signal of the switch tube in the external clamping module, improve the robustness of the system, and further reduce the risk of damage to electrical equipment caused by mis-opening of the power switch.
[0059] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.
Claims
1. A protection circuit for a power switch, characterized in that: The protection circuit comprises an internal clamping module, an external clamping module and a driving chip, wherein the internal clamping module is arranged inside the driving chip, and the external clamping module is arranged outside the driving chip; The first end of the internal clamp module is connected to the power switch control end of the power switch through the first end of the driving chip, the second end of the internal clamp module is connected to the negative terminal, and the control end of the internal clamp module is connected to the driving signal generating module of the driving chip; The control end of the external clamp module is connected to the second end of the driving chip, the first end of the external clamp module is connected to the power switch control end, the second end of the external clamp module is connected to the negative terminal, and the second end of the driving chip is connected to the driving signal generating module; The driving chip is used to collect the power switch control terminal voltage of the power switch during the shutdown process of the power switch, and generate a driving signal based on the power switch control terminal voltage and a preset voltage threshold through the driving signal generating module. If the power switch control terminal voltage is less than the preset voltage threshold, the driving signal triggers at least one of the internal clamping module and the external clamping module to turn on, so as to form at least one discharge loop.
2. The protection circuit of the power switch according to claim 1, characterized in that: The external clamping module includes a resistor, a capacitor and a first switch tube, the first end of the resistor is connected to the second end of the driving chip, the second end of the resistor is respectively connected to the control end of the first switch tube and the first end of the capacitor, the first end of the first switch tube is connected to the power switch control end, and the second end of the first switch tube is respectively connected to the negative terminal and the second end of the capacitor.
3. The protection circuit of the power switch according to claim 1, characterized in that: The internal clamping module is a second switch tube, the control end of the second switch tube is connected to the drive signal generating module for receiving the drive signal, the first end of the second switch tube is connected to the power switch control end through the first end of the drive chip, and the second end of the second switch tube is connected to the negative terminal.
4. The protection circuit of the power switch according to claim 1, characterized in that: The first end of the power switch is connected to the electrical device.
5. The protection circuit of the power switch according to claim 1, characterized in that: The driving chip further includes a state detection module for detecting the working state of the power switch, and the state detection module is connected to the power switch; When the power switch is in an on state, the internal clamping module and the external clamping module are triggered to be disconnected; When the power switch is in the off process, the driver chip is triggered to collect the power switch control terminal voltage of the power switch, and the drive signal generation module is triggered to generate a drive signal based on the power switch control terminal voltage and a preset voltage threshold.
6. The protection circuit of a power switch according to any one of claims 1 to 5, characterized in that: The power switch is a SiC power switch.
7. The protection circuit of a power switch according to any one of claims 1 to 5, characterized in that: The distance between the first end of the external clamp module and the control end of the power switch is less than a preset distance threshold.
8. The protection circuit of a power switch according to any one of claims 1 to 5, characterized in that: The negative terminal is a reference ground for the driving circuit.
9. A power switch with a protection circuit, characterized in that: A protection circuit comprising a power switch and the power switch as described in any one of claims 1 to 8, wherein a power switch control terminal of the power switch is connected to the protection circuit, a first terminal of the power switch is connected to an electrical device, and a second terminal of the power switch is connected to a negative terminal.
10. A power module, characterized in that: The power module includes an electrical device, a power switch and a protection circuit for the power switch as described in any one of claims 1 to 8, wherein a power switch control terminal of the power switch is connected to the protection circuit, a first terminal of the power switch is connected to the electrical device, and a second terminal of the power switch is connected to a negative terminal.