A power tube boost driving circuit

Abstract

The application provides a power tube boost driving circuit, comprising: a power supply module for providing a high-voltage input; an isolation driving module powered by the power supply module and generating a pulse control signal; a boost module for performing a switching operation of voltage boost based on the pulse control signal; a power tube connected to an output end of the boost module to conduct the raised voltage to a load; and a sampling module for sampling the output end of the boost module and feeding back a sampling voltage to the isolation driving module, so that the isolation driving module adjusts the pulse control signal based on the sampling voltage. The application can effectively improve the surge resistance of the driving circuit.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a power transistor boost drive circuit. Background Technology

[0002] In traditional power supply systems, especially in high-voltage applications, NMOS transistors are commonly used for power conversion and control. However, due to the high voltage in the power supply system, if a reverse voltage occurs in the circuit, the body diode of the NMOS transistor may conduct, causing current to flow through the body diode and potentially damaging the preceding circuitry. The forward connection method of NMOS transistors is insufficient to meet the reverse connection protection requirements of high-voltage power supply systems. Utility Model Content

[0003] In view of the problems existing in the prior art, this utility model proposes a power transistor boost drive circuit, which mainly solves the problem that the existing drive circuit has reverse voltage, which can easily lead to damage to the front-end circuit.

[0004] To achieve the above and other objectives, the technical solution adopted by this utility model is as follows.

[0005] This application provides a power transistor boost drive circuit, comprising: a power supply module; an isolation drive module, the power supply terminal of which is connected to the power supply module; a boost module, the control terminal of which is connected to the signal output terminal of the isolation drive module, and the input terminal of which is connected to the output terminal of the power supply module; a power transistor, the gate and source of which are connected to the output terminal of the boost module, and the drain of which is connected to a load; and a sampling module disposed at the output terminal of the boost module, the sampling node of which is connected to the feedback terminal of the isolation drive module.

[0006] In one embodiment of this application, the boost module includes a switching transistor, an inductor, a freewheeling diode, and a first capacitor. The gate of the switching transistor is connected to the signal output terminal, the source is connected to signal ground, and the drain is connected to the first terminal of the inductor and the anode of the freewheeling diode, respectively. The second terminal of the inductor is connected to the output terminal of the power supply module, the cathode of the freewheeling diode is connected to the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the second terminal of the inductor.

[0007] In one embodiment of this application, a current-limiting resistor is further provided between the power supply module and the isolation drive module. One end of the current-limiting resistor is connected to the power supply terminal of the isolation drive module, and the other end is connected to the positive output terminal of the power supply module. The negative output terminal of the power supply module is connected to signal ground.

[0008] In one embodiment of this application, the connection terminal between the current limiting resistor and the isolation drive module is also connected to signal ground through a fourth resistor.

[0009] In one embodiment of this application, the sampling module includes a first sampling resistor and a second sampling resistor connected in series, and the connection point of the first resistor and the second resistor is connected to the feedback terminal of the isolation drive module as a sampling point.

[0010] In one embodiment of this application, the power transistor is an NMOS transistor, the source of the power transistor is connected to the second terminal of the first capacitor, the gate is connected to the first terminal of the first capacitor, and the drain is connected to the load.

[0011] In one embodiment of this application, the power supply output voltage is 270V.

[0012] In one embodiment of this application, the switching transistor is an NMOS transistor, the positive terminal of the isolation driving module is connected to the gate of the switching transistor, and the negative terminal is connected to signal ground.

[0013] In one embodiment of this application, a Zener diode is further provided at the output terminal of the boost module to regulate the voltage of the power transistor.

[0014] In one embodiment of this application, the load includes a load resistor and a second capacitor. The first terminal of the second capacitor is connected to the first terminal of the load resistor and connected to the drain of the power transistor. The second terminal of the second capacitor is connected to the second terminal of the load resistor and connected to signal ground.

[0015] As described above, the power transistor boost drive circuit provided in this application has the following beneficial effects.

[0016] This application controls the boost process through a pulse control signal and samples the boost output. The pulse control signal is adjusted based on the sampled voltage to effectively prevent overvoltage. The PWM pulse is given to the switching transistor of the boost module, and the appropriate inductance enables the external NMOS to achieve a suitable turn-on time, thereby increasing the efficiency of the circuit and preventing turn-on surges. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit structure of the power transistor boost drive circuit in one embodiment of this application.

[0018] Label Explanation:

[0019] R1 - First sampling resistor; R2 - Second sampling resistor; R3 - Current limiting resistor; R4 - Fourth resistor; L - Inductor; C1 - First capacitor; C2 - Second capacitor; M1 - Switching transistor; M2 - Power transistor; D1 - Freewheeling diode; D2 - Zener diode. Detailed Implementation

[0020] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0021] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] Through research on utility model patents, it was found that:

[0023] In traditional power supply systems, especially in high-voltage applications, NMOS transistors are commonly used for power conversion and control. However, due to the high voltage in the power supply system, if a reverse voltage occurs in the circuit, the body diode of the NMOS transistor may conduct, causing current to flow through the body diode and potentially damaging the preceding circuitry. The forward connection method of NMOS transistors is insufficient to meet the reverse connection protection requirements of high-voltage power supply systems. Therefore, designing a circuit scheme that can drive NMOS transistors under high voltage conditions and prevent reverse connection damage is of significant practical importance. This utility model relates to a high-voltage NMOS transistor driven by a boost topology and a reverse connection protection circuit, including a PWM isolated drive module, a boost circuit, a power supply system, an NMOS circuit controlled by the boost circuit, a driver IC power supply circuit, a reverse current mitigation system, and a sampling circuit.

[0024] When the MOS channel of the power transistor is not open, current flows to the load through the body diode. When the channel opens, the current flow changes, and the voltage is sampled by the sampling resistor to coordinate the output pulse width of the preceding PWM waveform. This approach not only suppresses the inrush current when the NMOS transistor is turned on, reducing transmission losses, but also enables reverse polarity protection. Compared with traditional reverse polarity protection circuits, it is more independent, simpler, and generates less heat, significantly improving the stability and reliability of the power supply system.

[0025] Please see Figure 1 , Figure 1This is a schematic diagram of the circuit structure of a boost drive circuit according to one embodiment of this application. The power transistor boost drive circuit provided in this application includes: a power supply module; an isolation drive module, the power supply terminal of which is connected to the power supply module; a boost module, the control terminal of which is connected to the signal output terminal of the isolation drive module, and the input terminal of which is connected to the output terminal of the power supply module; a power transistor M2, the gate and source of which are connected to the output terminal of the boost module, and the drain of which is connected to the load; and a sampling module, which is disposed at the output terminal of the boost module, and the sampling node of the sampling module is connected to the feedback terminal of the isolation drive module.

[0026] In one embodiment, the boost module includes a switching transistor M1, an inductor L, a freewheeling diode D1, and a first capacitor C1. The gate of the switching transistor M1 is connected to the signal output terminal, the source is connected to signal ground, and the drain is connected to the first terminal of the inductor L and the anode of the freewheeling diode D1, respectively. The second terminal of the inductor L is connected to the output terminal of the power supply module, the cathode of the freewheeling diode D1 is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is connected to the second terminal of the inductor L.

[0027] In one embodiment of this application, a current-limiting resistor R3 is further provided between the power supply module and the isolation drive module. One end of the current-limiting resistor R3 is connected to the power supply terminal of the isolation drive module, and the other end is connected to the positive output terminal of the power supply module. The negative output terminal of the power supply module is connected to signal ground. For example, the isolation drive module can be a signal generator, which generates a pulse control signal and outputs it to the gate of the switching transistor M1 via an I / O port.

[0028] In one embodiment of this application, the connection terminal between the current limiting resistor R3 and the isolation drive module is also connected to signal ground through a fourth resistor R4.

[0029] In one embodiment, the sampling module includes a first sampling resistor R1 and a second sampling resistor R2 connected in series. The connection point of the first sampling resistor R1 and the second sampling resistor R2 is connected to the feedback terminal of the isolation drive module as a sampling point.

[0030] In one embodiment, the power transistor M2 is an NMOS transistor, the source of the power transistor M2 is connected to the second terminal of the first capacitor C1, the gate is connected to the first terminal of the first capacitor C1, and the drain is connected to the load.

[0031] In one embodiment, the power supply output voltage is 270V. Of course, the power supply voltage can also be set and adjusted according to actual application requirements, and there is no limitation here.

[0032] In one embodiment, the switching transistor M1 is an NMOS transistor, and the positive terminal of the isolation driving module is connected to the gate of the switching transistor M1, while the negative terminal is connected to signal ground.

[0033] In one embodiment, the output terminal of the boost module is further provided with a Zener diode D2, which regulates the voltage of the power transistor M2.

[0034] In one embodiment, the load includes a load resistor and a second capacitor C2. The first terminal of the second capacitor C2 is connected to the first terminal of the load resistor and connected to the drain of the power transistor M2. The second terminal of the second capacitor C2 is connected to the second terminal of the load resistor and connected to signal ground.

[0035] Specifically, switch M1 is off: During this stage, the PWM (pulse control signal) of the isolation drive module does not emit a waveform, and switch M1 is off. Switch M1 is supplied with a PWM wave through the driver chip of the isolation drive module. The driver chip is powered by the power supply voltage and current is limited by current-limiting resistor R3. Current flows through inductor L, which stores energy. The current in inductor L gradually increases, while the voltage across inductor L decreases. The side closer to the 270V power supply is the negative terminal, and the side closer to the anode of the freewheeling diode is the positive terminal, and inductor L begins to discharge. At this time, the freewheeling diode D1 connected to inductor L conducts, flowing to the gate G of power transistor M2. The G-level voltage gradually increases, and the GS voltage gradually increases. However, at this time, the GS voltage of power transistor M2 has not yet reached VTH (threshold threshold voltage), and the channel has not opened. Current flows from the power supply to the source of power transistor M2, through the body diode, to the drain, and then to the load.

[0036] Switching On Phase: During this phase, the isolation drive module sends a PWM pulse, turning on the switching transistor M1. Current flows from the power supply to the inductor L and the power transistor M2. Inductor L stores energy, and the current in inductor L gradually increases, while the voltage across inductor L rises. Current flows through the channel of switching transistor M1 to the negative terminal. The MOSFET Ciss of power transistor M2 fails to charge, and the MOSFET channel is turned off. When power transistor M2 is not conducting, if the drain voltage (D) is lower than the source voltage (S), i.e., the MOSFET is in reverse bias, the body diode will conduct, and current flows from the source to the drain. Current flows through the body diode of power transistor M2, and at this time, current flows through the load resistor Rload, charging capacitor C2.

[0037] VGS>Vth Stage: After several switching stages, when the gate-source voltage (G) begins to rise and the VGS (gate-source voltage) of the MOSFET reaches or exceeds the VTH (threshold voltage), the channel of power transistor M2 will begin to conduct. At this time, current will mainly flow through the channel and no longer through the body diode. Once the channel is formed, since the on-resistance RDS(on) of the channel is much smaller than the forward on-resistance of the body diode, the current will preferentially choose to flow through the channel because it is a low-impedance path. At this time, the body diode will be turned off and will hardly conduct anymore. Current flows to the load through the channel. If the switching frequency is high enough, neither the inductor L nor the first capacitor C1 will be fully discharged, and the output load voltage will always be higher than the input voltage source. This is continuous conduction mode (CCM). The longer the PWM high level lasts (i.e., the longer the switching transistor M1 is on), the higher the output voltage V_g will be. If the duty cycle (the switching time relative to the total switching cycle) and the number of switching cycles are properly controlled, the circuit can enable the NMOS to achieve higher power, surge suppression, and reverse protection.

[0038] In practice, the node voltage between sampling resistors R1 and R2 is transmitted to the feedback terminal of the driver IC of the isolation driver module to adjust the drive PWM wave.

[0039] Based on the technical solution of the above embodiments of this application, when the MOS channel of power transistor M2 is not open, the current flows to the load through the body diode. When the channel is open, the current flow through the circuit changes. Moreover, by sampling the voltage through the sampling resistor to coordinate the pulse width state of the preceding PWM waveform, this approach can not only suppress the surge current when the NMOS is turned on and reduce transmission loss, but also achieve the circuit's reverse connection protection function. Compared with traditional reverse connection protection circuits, it has the characteristics of being independent, simple, and generating less heat, which can significantly improve the stability and reliability of the power supply system.

[0040] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A power transistor boost drive circuit, characterized in that, include: Power supply module; An isolated driver module, the power supply terminal of which is connected to the power supply module; The boost module has its control terminal connected to the signal output terminal of the isolation drive module and its input terminal connected to the output terminal of the power supply module. The power transistor has its gate and source connected to the output terminal of the boost module, and its drain connected to the load. A sampling module is located at the output terminal of the boost module, and the sampling node of the sampling module is connected to the feedback terminal of the isolation drive module.

2. The power transistor boost drive circuit according to claim 1, characterized in that, The boost module includes a switching transistor, an inductor, a freewheeling diode, and a first capacitor. The gate of the switching transistor is connected to the signal output terminal, the source is connected to signal ground, and the drain is connected to the first terminal of the inductor and the anode of the freewheeling diode, respectively. The second terminal of the inductor is connected to the output terminal of the power supply module, the cathode of the freewheeling diode is connected to the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the second terminal of the inductor.

3. The power transistor boost drive circuit according to claim 1, characterized in that, A current-limiting resistor is also provided between the power supply module and the isolation drive module. One end of the current-limiting resistor is connected to the power supply terminal of the isolation drive module, and the other end is connected to the positive output terminal of the power supply module. The negative output terminal of the power supply module is connected to signal ground.

4. The power transistor boost drive circuit according to claim 3, characterized in that, The connection point between the current-limiting resistor and the isolation drive module is also connected to signal ground via a fourth resistor.

5. The power transistor boost drive circuit according to claim 1, characterized in that, The sampling module includes a first sampling resistor and a second sampling resistor connected in series. The connection point of the first sampling resistor and the second sampling resistor serves as a sampling point and is connected to the feedback terminal of the isolation drive module.

6. The power transistor boost drive circuit according to claim 2, characterized in that, The power transistor is an NMOS transistor. The source of the power transistor is connected to the second terminal of the first capacitor, the gate is connected to the first terminal of the first capacitor, and the drain is connected to the load.

7. The power transistor boost drive circuit according to claim 2, characterized in that, The power supply output voltage is 270V.

8. The power transistor boost drive circuit according to claim 2, characterized in that, The switching transistor is an NMOS transistor. The positive terminal of the isolation drive module is connected to the gate of the switching transistor, and the negative terminal is connected to signal ground.

9. The power transistor boost drive circuit according to claim 3, characterized in that, The output terminal of the boost module is also equipped with a Zener diode, which regulates the voltage of the power transistor.

10. The power transistor boost drive circuit according to claim 6, characterized in that, The load includes a load resistor and a second capacitor. The first terminal of the second capacitor is connected to the first terminal of the load resistor and connected to the drain of the power transistor. The second terminal of the second capacitor is connected to the second terminal of the load resistor and connected to signal ground.

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