Driving level adjusting circuit of power switch and power conversion system

Abstract

The invention discloses a driving level adjusting circuit of a power switch and a power conversion system, and relates to the field of circuit design. The circuit comprises a resonance module which performs electromagnetic heating or power conversion based on an LC parallel resonance principle; the power switch is used for adjusting the working mode of the resonance module; the driving module is used for outputting a driving voltage signal Gate to the power switch so as to control the on-off and low-voltage and high-voltage working states of the power switch; the micro-control unit outputs an enable signal EN and a switching signal SW, and the enable signal EN adjusts the driving voltage signal Gate according to the working mode of the resonance module and controls the state of the power switch in the ZVS continuous mode or discontinuous mode; and the switching signal SW adjusts the driving voltage signal Gate through the driving module to control the state of the power switch. According to the scheme, the surge current is effectively controlled by adjusting the driving voltage of the power switch, the requirements of different working modes and the power switch can be met, and the adaptability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the field of circuit design, and in particular to a driving level adjustment circuit of a power switch and a power conversion system. Background Art

[0002] LC parallel resonant circuits are widely used in kilowatt-level power conversion systems because they are easy to implement ZVS (Zero Voltage Switching). For example, in an induction cooker, a high-frequency AC current is generated through an LC parallel resonant circuit, which drives the coil disk to generate a changing magnetic field, causing eddy currents to be generated inside the pot to achieve heating. The following is an introduction to the induction cooker as an example.

[0003] like Figure 1 As shown, the heating system of the existing induction cooker is mainly composed of a resonant module (L2, C2), a driving module, a power switch and a microcontroller unit. In order to reduce the power source impedance of the input voltage and reduce the mutual interference between the grid noise and the system switch noise, the system input end is usually equipped with a filter module (L1, C1), and the resonant module obtains energy through the low-impedance C1. However, when the resonant module stops working for more than one AC cycle, C1 will be charged to the peak value of the grid voltage. When restarting, due to the existence of C1, a large surge current will be generated when the power switch (such as IGBT) is turned on, which will cause an impact on the IGBT and reduce its reliability. After the initial pulse, the system enters the ZVS state and the impact current disappears. However, as the load decreases, the system gradually exits the ZVS mode, and the impact current increases again, thereby limiting the minimum load power for the system to work safely. Although the intermittent working mode with low valley voltage can reduce the surge current, after each pulse stops, C1 will be charged to the peak voltage again, causing the surge current to appear again when restarting.

[0004] In order to suppress surge current under various working conditions, the industry has proposed a method for controlling surge current by adjusting the driving voltage of the power switch. This method reduces the driving voltage to an undersaturated gate voltage level when the power switch is initially turned on or restored, thereby forcing a reduction in the turn-on current. However, due to differences in undersaturated gate voltages of power switches of different models and manufacturers, the setting of the driving voltage cannot adapt to different types of power switches. Therefore, it is necessary to provide an adjustable power switch driving circuit to meet the surge current limiting conditions of using different power switches. Summary of the invention

[0005] The purpose of the present invention is to provide a driving level adjustment circuit for a power switch and a power conversion system, which can effectively control the surge current by adjusting the driving voltage of the power switch, meet the requirements of different working modes and power switches, and improve the adaptability and reliability of the system.

[0006] To achieve the above object, the present invention discloses the following technical solution: In one aspect, the present invention provides a driving level adjustment circuit for a power switch, comprising: Resonance module, which performs electromagnetic heating or power conversion based on the LC parallel resonance principle; A power switch connected to the resonance module and used to adjust the working mode of the resonance module, including a ZVS continuous mode and a discontinuous mode; A driving module, connected to the power switch, and configured to output a driving voltage signal Gate to the power switch to control the on / off state and the low-voltage and high-voltage working states of the power switch; A microcontrol unit is connected to the driving module and is used to output an enable signal EN and a switch signal SW to the driving module, wherein the enable signal EN adjusts the drive voltage signal Gate output by the driving module according to the working mode of the resonance module to control the state of the power switch in the ZVS continuous mode or the discontinuous mode; and the switch signal SW adjusts the drive voltage signal Gate of the power switch through the driving module to control the on / off state and the low-voltage and high-voltage working states of the power switch.

[0007] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the working mode of the resonance module includes a ZVS continuous mode and a discontinuous mode; When the resonant module operates in the ZVS continuous mode, the enable signal EN=L=0, and the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch operates in a high voltage state; When the resonance module operates in the discontinuous mode, the enable signal EN=H=1. When the power switch is turned on, the driving module first outputs a low driving voltage signal Gate to the power switch to turn on the power switch in a low voltage state. Then, after a preset time, the driving module outputs a high driving voltage signal Gate to the power switch to enable the power switch to work normally in a high voltage state.

[0008] Optionally, in the above-mentioned driving level adjustment circuit, the driving module includes a delay module TD, an AND gate AND, a second NOT gate INV2 and an OR gate OR; wherein, The input end of the delay module TD is connected to the switch signal SW, and the output end thereof is connected to one input end of the AND gate AND; the other input end of the AND gate AND is connected to the enable signal EN, and the output end of the AND gate AND is connected to the first input end of the OR gate OR; the switch signal SW is connected to the second input end of the OR gate OR after passing through the second NOT gate INV2, and the output end of the OR gate OR outputs the control signal S.

[0009] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the working mode of the resonance module includes a ZVS continuous mode, a light discontinuous mode and a heavy discontinuous mode, and the enable signal EN includes EN_H and EN_L; When the resonant module operates in the ZVS continuous mode, the enable signal EN_H=0 and EN_L=0, and the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch operates in a high voltage state; When the resonant module operates in the light discontinuous mode, the enable signal EN_H=1 and EN_L=0, and when the power switch is turned on, the driving module first outputs a low driving voltage signal Gate to the power switch, so that the power switch is turned on in a low voltage state, and then after a preset time, the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch works normally in a high voltage state; When the resonance module operates in the heavy discontinuous mode, the enable signal EN_H=0 and EN_L=1, and the driving module outputs a low driving voltage signal Gate to the power switch, so that the power switch operates in a low voltage state.

[0010] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the driving module includes a delay module TD, an AND gate AND, a second NOT gate INV2 and an OR gate OR; wherein, The input end of the delay module TD is connected to the switch signal SW, and the output end thereof is connected to one input end of the AND gate AND; the other input end of the AND gate AND is connected to the enable signal EN_H, and the output end of the AND gate AND is connected to the first input end of the OR gate OR; the switch signal SW is connected to the second input end of the OR gate OR after passing through the second NOT gate INV2; the enable signal EN_L is connected to the third input end of the OR gate OR; the output end of the OR gate OR outputs the control signal S.

[0011] Furthermore, in the above-mentioned driving level adjustment circuit of the power switch, the driving module also includes a current source I, a first resistor R1, a second resistor R2, a first switch K1, a second switch K2, a first switch tube M1, a second switch tube M2, a first NOT gate INV1 and a follower Buffer; wherein, The power supply voltage VCC is grounded via the current source I and the second resistor R2 in sequence; the power supply voltage VCC is also grounded via the first switch tube M1 and the first resistor R1 in sequence; the power supply voltage VCC is also grounded via the second switch tube M2 and the second switch K2 in sequence; the positive input end of the follower Buffer is connected to the node A between the current source I and the second resistor R2, the current output end of the first switch tube M1 is connected to the current output end of the second switch tube M2 and is connected to the reverse input end of the follower Buffer, and serves as the output end of the driving voltage signal Gate; the control end of the first switch tube M1 is connected to the output end of the follower Buffer, and the control end of the second switch tube M2 is connected to the control signal S; the switch signal SW is also connected to the control end of the first switch K1 and the control end of the second switch K2 respectively after passing through the first NOT gate INV1.

[0012] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the second resistor R2 is an external adjustable resistor for generating a driving low voltage VA, and the amplitude of the driving low voltage VA is proportional to the resistance value of the second resistor R2.

[0013] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the power switch is an IGBT tube, the first switch tube M1 is an NMOS tube, and the second switch tube M2 is a PMOS tube.

[0014] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the preset duration of the delay module TD is set to be greater than 3μs and less than the minimum on-time of the switch signal SW.

[0015] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, when the working mode of the resonance module includes a ZVS continuous mode and a discontinuous mode: When the resonant module works in the ZVS continuous mode, the micro control unit outputs an enable signal EN=L=0; when the switch signal SW is at a high level, the drive voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage working state; when the switch signal SW is at a low level, the drive voltage signal Gate is pulled low, and the power switch is turned off; When the resonance module operates in the discontinuous mode, the micro control unit outputs an enable signal EN=H=1; when the switch signal SW changes from a low level to a high level, the driving voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset time length of the delay module TD, and the power switch is in a low-voltage working state; when the preset time length of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is turned into a high-voltage working state; when the switch signal SW changes from a high level to a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off.

[0016] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, when the working mode of the resonance module includes a ZVS continuous mode, a light discontinuous mode and a heavy discontinuous mode: When the resonant module works in the ZVS continuous mode, the micro control unit outputs the enable signal EN_H=0 and EN_L=0; when the switch signal SW is at a high level, the drive voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage working state; when the switch signal SW is at a low level, the drive voltage signal Gate is pulled low, and the power switch is turned off; When the resonance module operates in the light discontinuous mode, the micro control unit outputs an enable signal EN_H=1 and EN_L=0; when the switch signal SW changes from a low level to a high level, the driving voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset time length td of the delay module TD, and the power switch is in a low-voltage working state; after the preset time length td of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is turned into a high-voltage working state; when the switch signal SW changes from a high level to a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off.

[0017] When the resonance module works in the heavy discontinuous mode, the micro control unit outputs an enable signal EN_H=0 and EN_L=1; the driving module outputs VA as a low driving voltage signal Gate to the power switch, and the power switch is in a low voltage working state.

[0018] Optionally, the driving level adjustment circuit of the power switch mentioned above further includes: A rectifier module, used for rectifying the input grid voltage; A filtering module, used for filtering the rectified voltage; The power supply module is used to provide 18V high voltage for the power switch and 5V low voltage for the micro control unit.

[0019] Another aspect of the present invention provides a power conversion system, comprising the driving level adjustment circuit of the power switch as described in the first aspect.

[0020] The effects provided in the content of the invention are only the effects of the embodiments, not all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects: The present application provides a driving level adjustment circuit and a power conversion system for a power switch, which includes a driving level adjustment circuit resonance module, a power switch, a driving module and a microcontroller unit. The resonance module performs electromagnetic heating or power conversion based on the principle of LC parallel resonance; the power switch is connected to the resonance module to adjust the working mode of the resonance module; the driving module outputs a driving voltage signal Gate to the power switch to control its on / off state and low-voltage and high-voltage working states; the microcontroller unit adjusts the output of the driving module by outputting an enable signal EN and a switch signal SW, so that the driving voltage signal Gate adapts to different working modes. This solution realizes flexible adjustment of the driving voltage of the power switch through the coordinated work of each module unit, thereby effectively controlling the surge current, meeting the needs of different working modes and power switches, and improving the adaptability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] Figure 1 It is a schematic diagram of a heating system of an induction cooker in the prior art; Figure 2 Output characteristic curves of four different types of IGBTs; Figure 3 A schematic diagram of a driving level adjustment circuit structure of a power switch according to an embodiment of the present application; Figure 4 for Figure 3 A logic control circuit diagram of the middle drive module; Figure 5 for Figure 3 Another logic control circuit diagram of the middle drive module; Figure 6 for Figure 3 A circuit implementation schematic diagram of the middle drive module; Figure 7 for Figure 6 A waveform diagram of the switch signal SW and the driving voltage signal Gate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] It should be noted that references to "one embodiment", "embodiment", "example embodiment", etc. in this specification refer to the embodiment being described which may include specific features, structures or characteristics, but not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Furthermore, when describing specific features, structures or characteristics in conjunction with an embodiment, whether or not there is an explicit description, it is indicated that incorporating such features, structures or characteristics into other embodiments is within the knowledge of those skilled in the art.

[0025] As described in the background technology, the LC parallel resonant circuit is widely used in power conversion systems because it is easy to achieve ZVS. For the sake of convenience, the following takes an induction cooker as an example to introduce the relevant circuits. It should be noted that these circuit structures are also applicable to other systems using the LC parallel resonant method, and are not limited to the application of induction cookers.

[0026] refer to Figure 1 As shown, the heating system of the existing induction cooker mainly includes a rectifier module (D11, D12, D13, D14), a filter module (L1, C1), a resonance module 110, a power switch 120 (hereinafter, IGBT is taken as an example), a drive module 130, a micro control unit 140 and a power module. During operation, the micro control unit 140 controls the drive module 130 to provide a conduction signal and a drive voltage to the IGBT, so that the resonance module 110 generates a resonant current, generates a periodically changing magnetic field in the coil disk, and realizes heating of the load.

[0027] When the system works in high power or continuous mode, the energy of the filter capacitor C1 cannot be maintained under a large load, and its voltage will follow the sine wave voltage after full bridge rectification. At this time, the micro control unit 140 controls the drive module 130 to turn on the IGBT at the LC resonance zero-crossing moment of each switching cycle, so that the IGBT starts in the ZVS mode. When the system works in low power or discontinuous mode, an intermittent working mode is adopted. In this mode, the system works for a period of time (several AC cycles) and then stops for a period of time (several AC cycles, called dead time). As the system power decreases, the duty cycle of the working cycle also decreases to achieve low power operation. During the dead time, the load is almost zero, and the filter capacitor C1 cannot be discharged, and the highest voltage after the input AC rectification (such as 310V when the input AC220V) will be maintained. At this time, even if the micro control unit 140 controls the drive module 130 to turn on the IGBT at the time when the AC voltage passes zero, since the 310V voltage on the filter capacitor C1 is applied to the IGBT, the IGBT is turned on in a hard switch mode, and a large current of more than 200A may be generated instantly. This large current will have a serious impact on the IGBT, reducing its reliability and may even cause damage.

[0028] The power module usually has two output voltages: 18V high voltage and 5V low voltage. Among them, the 18V high voltage is used to drive the IGBT, and the 5V low voltage is used to power the microcontroller unit 140 and other modules. When the system operates in a low-power intermittent mode, a large surge current will be generated when the IGBT is turned on after the dead zone ends. In order to reduce this surge current, a special IGBT driver IC is provided in the prior art to control the current size of the IGBT by reducing the gate voltage of the IGBT, and the current is usually limited to about 20-25A. Taking the IHW20N135R3 IGBT as an example, when the applied gate drive voltage is 9V, the current capacity of its collector is 20-30A, and the impact current is significantly reduced compared to the 18V drive voltage condition. However, this method still has certain shortcomings, that is, once the model of the IGBT is selected, its gate voltage is difficult to adjust, resulting in the inability to adapt to the needs of other IGBT models. For example Figure 2 As shown in the figure, there are four different types of IGBT output characteristic curves. When the saturation current is between 20-30A, the corresponding V GE The voltages are different, such as 9V, 10V, 11V, etc., or even more other voltage parameters. If the voltage setting in the driver IC is fixed, it will be difficult to be compatible with different types of IGBTs. To solve this problem, the embodiment of the present application provides a drive level adjustment circuit and system for a power switch, which can flexibly adjust its drive voltage according to the characteristics of different types of IGBTs in a low-power intermittent working mode, thereby better controlling the surge current and improving the adaptability and reliability of the system.

[0029] In the prior art, the driving module 130 is used to amplify the received small signal voltage or current into a large signal voltage or current, thereby controlling the working state of the power switch 120. The existing driving module 130 usually has only two output states, high level and low level. Among them, the high level is used to turn on the IGBT, and the low level is used to turn off the IGBT. In this way, the driving module 130 can control the state of the power switch 120 to ensure the normal operation of the system.

[0030] refer to Figure 3 , Figure 3 The schematic diagram of the structure of a driving level adjustment circuit of a power switch according to an embodiment of the present application is shown. The circuit includes a resonance module 210 , a power switch 220 , a driving module 230 and a micro control unit 240 . The resonance module 210 is based on the LC parallel resonance principle and generates a resonance current to perform electromagnetic heating or power conversion on the load; the power switch 220 is connected to the resonance module 210 and is used to adjust the working mode of the resonance module 210, including the ZVS continuous mode and the discontinuous mode, to adapt to different power requirements; the driving module 230 is connected to the power switch 220 and is used to output a driving voltage signal Gate to the power switch 220 to control the on / off state and the low-voltage and high-voltage working states of the power switch 220; the microcontroller unit 240 is connected to the driving module 230 and is used to output an enable signal EN and a switch signal SW to the driving module 230, the enable signal EN is used to adjust the driving voltage signal Gate output by the driving module 230 according to the working mode of the resonance module 210 (i.e., the output power set by the system) to control the state of the power switch 240 in the ZVS continuous mode or the discontinuous mode; the switch signal SW is used to adjust the driving voltage signal Gate of the power switch 220 through the driving module 230 to control the on / off state and the low-voltage and high-voltage working states of the power switch 220.

[0031] In some embodiments, the working modes of the resonance module 210 include a ZVS continuous mode and a discontinuous mode. When the resonance module 210 operates in the ZVS continuous mode, the microcontroller unit 240 outputs an enable signal EN of a low level (EN=L). At this time, the driver module 230 outputs a high drive voltage signal Gate to the power switch 220 to enable it to operate under a high voltage state. When the resonance module 210 operates in the discontinuous mode, the microcontroller unit 240 outputs an enable signal EN of a high level (EN=H). At this time, when the power switch 220 is turned on, the driver module 210 first outputs a low drive voltage signal Gate to the power switch 220, so that the power switch 220 is turned on under a low voltage state to limit the conduction current. Then, after a preset time, the driver module 210 outputs a high drive voltage signal Gate to the power switch 220 to enable the power switch 220 to operate normally under a high voltage state.

[0032] Figure 4 for Figure 3 A logic control circuit diagram of the drive module. Figure 4 As shown, in this embodiment, the driving module 230 includes a delay module TD, an AND gate AND, a second NOT gate INV2 and an OR gate OR. Among them, the input end of the delay module TD is connected to the switch signal SW, and its output end is connected to one input end of the AND gate AND; the other input end of the AND gate AND is connected to the enable signal EN, and the output end of the AND gate AND is connected to the first input end of the OR gate OR; the switch signal SW is connected to the second input end of the OR gate OR after passing through the second NOT gate INV2, and the output end of the OR gate OR outputs a control signal S, which is used to adjust the driving voltage signal Gate of the power switch 220.

[0033] In other embodiments, the working modes of the resonance module 210 include a ZVS continuous mode, a light intermittent mode, and a heavy intermittent mode (i.e., the intermittent mode is further divided into a light intermittent mode and a heavy intermittent mode), and the enable signal EN includes EN_H and EN_L. The microcontroller unit 240 outputs the corresponding enable signal EN according to the setting of the system output power. For example, when the system outputs high power (corresponding to heavy load), the enable signal is EN_H=0 and EN_L=0, and the resonance module 210 operates in the ZVS continuous mode. When the system outputs low power (corresponding to light load), the enable signal is EN_H=1 and EN_L=0, and the resonance module operates in a light intermittent mode; when the system outputs minimum power (corresponding to minimum load), the enable signal is EN_H=0 and EN_L=1, and the resonance module operates in a heavy intermittent mode.

[0034] Specifically, when the resonance module 210 operates in the ZVS continuous mode, the micro control unit 240 outputs the enable signal EN_H=0 and EN_L=0, at which time the driving module 230 outputs the high drive voltage signal Gate to the power switch 220, so that it operates in a high voltage state. When the resonance module 210 operates in the heavy discontinuous mode, the micro control unit 240 outputs the enable signal EN_H=0 and EN_L=1, at which time the driving module 230 outputs the low drive voltage signal Gate to the power switch 220, so that it operates in a low voltage state to limit the operating current. When the resonance module 210 operates in the light discontinuous mode, the micro control unit 240 outputs the enable signal EN_H=1 and EN_L=0. At this time, when the power switch 220 is turned on, the driving module 230 first outputs a low driving voltage signal Gate to the power switch 220, so that it is turned on in a low voltage state to limit the conduction current. Then, after a preset low voltage time, the driving module 230 outputs a high driving voltage signal Gate to the power switch 220, so that it works normally in a high voltage state to meet the power demand.

[0035] Figure 5 for Figure 3Another logic control circuit diagram of the drive module. Figure 5 As shown, in this embodiment, the driving module 230 includes a delay module TD, an AND gate AND, a second NOT gate INV2 and an OR gate OR. Among them, the input end of the delay module TD is connected to the switch signal SW, and its output end is connected to one input end of the AND gate AND; the other input end of the AND gate AND is connected to the enable signal EN_H, and the output end of the AND gate AND is connected to the first input end of the OR gate OR; the switch signal SW is connected to the second input end of the OR gate OR after passing through the second NOT gate INV2, and the enable signal EN_L is connected to the third input end of the OR gate OR; the output end of the OR gate OR outputs the control signal S, and the control signal S is used to adjust the driving voltage signal Gate of the power switch 220.

[0036] From the above analysis, it can be seen that the driving level adjustment circuit of this embodiment realizes flexible adjustment of the driving voltage of the power switch 220 through the coordinated work of the resonance module 210, the power switch 220, the driving module 230 and the micro control unit 240, thereby effectively controlling the surge current, meeting the requirements of different working modes and power switches, and significantly improving the adaptability and reliability of the system.

[0037] Figure 6 for Figure 3 A circuit implementation schematic diagram of the drive module. Figure 6 As shown, the driving module 230 also includes a current source I, a first resistor R1, a second resistor R2, a first switch K1, a second switch K2, a first switch tube M1, a second switch tube M2, a first NOT gate INV1 and a follower Buffer. Among them, the power supply voltage VCC is connected to the ground through the current source I and the second resistor R2 in sequence; the power supply voltage VCC is also connected to the ground through the first switch tube M1 and the first resistor R1 in sequence; the power supply voltage VCC is also connected to the ground through the second switch tube M2 and the second switch K2 in sequence; the positive input terminal of the follower Buffer is connected to the node A between the current source I and the second resistor R2, the current output terminal of the first switch tube M1 is connected to the current output terminal of the second switch tube M2 and connected to the reverse input terminal of the follower Buffer, and serves as the output terminal of the driving voltage signal Gate; the control terminal of the first switch tube M1 is connected to the output terminal of the follower Buffer, and the control terminal of the second switch tube M2 is connected to the control signal S; the switch signal SW is also connected to the control terminal of the first switch K1 and the control terminal of the second switch K2 respectively after passing through the first NOT gate INV1.

[0038] In this embodiment, the second resistor R2 of the driving module 230 is set as an external adjustable resistor, and its end can generate a driving low voltage VA, and the amplitude of the driving low voltage VA is proportional to the resistance value of the second resistor R2. In practical applications, the end voltage of the second resistor R2 can be flexibly adjusted according to needs, thereby realizing the driving voltage control of different types of power switches and meeting the needs of different working modes and power switches.

[0039] In some embodiments, the power switch is an IGBT tube to meet the needs of high power. The first switch tube M1 is an NMOS tube, and the second switch tube M2 is a PMOS tube to achieve fast switch control and efficient voltage drive.

[0040] In some embodiments, the preset time length td of the delay module TD is set to be greater than 3µs and less than the minimum on-time length of the switch signal SW, thereby effectively avoiding slow circuit response due to excessive delay, and at the same time ensuring that when the switch signal SW switches, the drive module 230 can generate the control signal S in time to ensure that the circuit can smoothly switch to the high voltage state after the delay.

[0041] according to Figure 4 and Figure 6 The circuit structure, when the working mode of the resonant module is ZVS continuous mode and discontinuous mode, its control method is as follows: When the resonant module 210 works in the ZVS continuous mode, the micro control unit 240 outputs the enable signal EN=L=0; at this time, when the switch signal SW is at a high level, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch 220 is in a high-voltage working state; when the switch signal SW is at a low level, the driving voltage signal Gate is pulled low (grounded), and the power switch 220 is turned off; When the resonance module 210 works in the discontinuous mode, the micro control unit 240 outputs the enable signal EN=H=1; at this time, when the switch signal SW changes from a low level to a high level, the driving voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset time length td of the delay module TD, and the power switch 220 is in a low-voltage working state; when the preset time length td of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch 220 is turned into a high-voltage working state; when the switch signal SW changes from a high level to a low level, the driving voltage signal Gate is pulled down, and the power switch 220 is turned off. Therefore, the circuit of this embodiment can ensure the smooth switching and safe operation of different working modes and different power switches by adjusting the driving voltage and the delay time length.

[0042] according to Figure 5 and Figure 6 The circuit structure, when the working mode of the resonant module is ZVS continuous mode, light discontinuous mode and heavy discontinuous mode, its control method is as follows: When the resonant module 210 works in the ZVS continuous mode, the micro control unit 240 outputs the enable signal EN_H=0 and EN_L=0; at this time, when the switch signal SW is at a high level, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch 220 is in a high-voltage working state; when the switch signal SW is at a low level, the driving voltage signal Gate is pulled low (grounded), and the power switch 220 is turned off; When the resonance module 210 works in the light discontinuous mode, the micro control unit 240 outputs the enable signal EN_H=1 and EN_L=0; at this time, when the switch signal SW changes from a low level to a high level, the driving voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset time length td of the delay module TD, and the power switch 220 is in a low-voltage working state; when the preset time length td of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch 220 is turned into a high-voltage working state; when the switch signal SW changes from a high level to a low level, the driving voltage signal Gate is pulled low, and the power switch 220 is turned off; When the resonant module 210 works in the heavy discontinuous mode, the micro control unit 240 outputs the enable signal EN_H=0 and EN_L=1; at this time, the driving module 230 outputs VA as the driving voltage signal Gate, and the power switch 220 is in a low-voltage working state. Therefore, the circuit of this embodiment can further ensure the smooth switching and safe operation of different working modes and different power switches by adjusting the driving voltage and delay time.

[0043] In addition, in some embodiments, the drive regulation circuit also includes: a rectifier module for rectifying the input grid voltage; a filter module for filtering the rectified voltage; a power supply module for providing 18V high voltage (power supply voltage VCC) for the power switch 220, and 5V low voltage for the micro control unit and other modules.

[0044] Figure 7 for Figure 5 and Figure 6 The signal waveform of the drive level adjustment circuit of the medium power switch. Figure 5 and Figure 6 Taking the circuit structure of the driving module in the example, its working principle and working process are further described in detail. Figure 4 and Figure 6 The circuit structure of the drive module, its working principle and working process can be referred to Figure 5 and Figure 6 The relevant part of the driver module.

[0045] If the system is set to low power (light intermittent mode) output, the micro control unit 240 outputs the enable signal EN_H=1 and EN_L=0. When the switch signal SW changes from low level to high level, the delay module TD detects the rising edge of the switch signal SW and starts to delay the preset time length td. After the delay ends, the output of the delay module TD changes from high level to low level. Within the preset time length td, the delay module TD outputs a high level, and the switch signal SW is also a high level at this time, so the AND gate And outputs a high level, thereby making the OR gate OR output control signal S a high level, and the second switch tube M2 is turned off. At the same time, when SW is a high level, it outputs a low level after passing through the first invertor INV1, so that the first switch K1 and the second switch K2 are both turned off. At this time, the driving voltage end (Gate end) is connected to the voltage signal VA of the first resistor R1. Since the constant current source I provides a constant current and the second resistor R2 is an adjustable resistor, the voltage VA at its end can be adjusted by adjusting the resistance value of the second resistor R2, and the amplitude of VA is proportional to the resistance value. At this time, the follower Buffer transmits the voltage VA on the second resistor R2 to the first resistor R1, so that the driving voltage signal Gate is equal to VA, and the voltage value of VA is lower than the power supply voltage VCC.

[0046] Therefore, when designing the circuit, only the voltage range of VA needs to be considered. When the model of the IGBT is determined, the resistance value of the second resistor R2 can be adjusted according to its parameters to set a suitable VA voltage, thereby limiting the on-current of the IGBT. Even if the voltage of the filter capacitor is the superposition of the resonant voltage and the rectified mains voltage, the current flowing through the IGBT can still be controlled within a reasonable range due to the low driving voltage at this time, thereby effectively discharging the voltage on the filter capacitor C1 at the moment of on-time.

[0047] When the preset time length td of the delay module TD ends, its output flips to a low level, so that the output of the AND gate And also becomes a low level. At this time, the switch signal SW outputs a low level after passing through the second NOT gate INV2. Since both input ends of the OR gate OR are low levels, the control signal S changes from a high level to a low level, and the second switch tube M2 is turned on. Since M2 is turned on, the first switch K1 and the second switch K2 are both turned off. At this time, the follower Buffer does not work, and the driving voltage signal Gate is directly connected to the power supply voltage VCC. The IGBT starts to work at a high voltage to meet the power demand.

[0048] When the switch signal SW is at a low level, the second invertor INV2 outputs a high level, the control signal S output by the OR gate OR becomes a high level, and the second switch tube M2 is turned off. At the same time, SW outputs a high level after passing through the first invertor INV1, so that the first switch K1 and the second switch K2 are both closed, the Gate voltage is pulled down, and the IGBT is turned off.

[0049] At the beginning of the next switching signal SW cycle, the above steps are repeated. That is, the driving voltage signal Gate is first connected to the adjustable low voltage VA to limit the on-current of the IGBT. After the preset delay time td, the driving voltage signal Gate is switched to the high voltage VCC to drive the IGBT to work normally. In this way, the current flowing through the IGBT can be effectively controlled, thereby preventing the IGBT from being damaged by the instantaneous large current.

[0050] If the system selects high power (ZVS continuous mode) operation, the micro control unit 240 outputs the enable signal EN_H=0 and EN_L=0. At this time, the AND gate AND outputs a low level, the first input terminal and the third input terminal of the OR gate OR are both connected to a low level, and the control signal S output by the OR gate OR depends on the switch signal SW. When the switch signal SW is high, the second NOT gate INV2 outputs a low level, and the control signal S output by the OR gate OR is low, and the second switch tube M2 is turned on. At the same time, the first NOT gate INV1 outputs a low level, the first switch K1 and the second switch K2 are both turned off, and the driving voltage signal Gate is connected to the power supply voltage VCC. At this time, the IGBT works under high voltage, and the follower Buffer does not work. When the switch signal SW is low, the AND gate AND still outputs a low level, and the first input terminal and the third input terminal of the OR gate OR are both connected to a low level, but because the second NOT gate INV2 outputs a high level, the control signal S output by the OR gate OR becomes a high level, and the second switch tube M2 is turned off. At the same time, the first NOT gate INV1 outputs a high level, so that the first switch K1 and the second switch K2 are both closed. At this time, the Gate voltage is pulled low, so that the IGBT is turned off.

[0051] If the system selects the minimum power (heavy intermittent mode) operation, the micro control unit 240 outputs the enable signal EN_H=0 and EN_L=1. At this time, the third input terminal of the OR gate OR is connected to a high level, the OR gate output control signal S is always at a high level, and the second switch tube M2 is turned off. When SW is at a high level, it outputs a low level after passing through the first invertor INV1, so that the first switch K1 and the second switch K2 are both turned off. At this time, the Gate terminal is connected to the voltage signal VA of the first resistor R1. Since the constant current source I provides a constant current and the second resistor R2 is an adjustable resistor, the voltage VA at its end can be adjusted by adjusting the resistance value of the second resistor R2. At this time, the follower Buffer transmits the voltage VA on the second resistor R2 to the first resistor R1, so that the driving voltage signal Gate is equal to VA, and the voltage value of VA is lower than the power supply voltage VCC. When the model of the IGBT is determined, the resistance value of the second resistor R2 can be adjusted according to its parameters to set a suitable VA voltage to limit the on-current of the IGBT.

[0052] When the switch signal SW changes from a high level to a low level, SW outputs a high level after passing through the first invertor INV1, so that the first switch K1 and the second switch K2 are both closed, and the Gate voltage is pulled down, thereby turning off the IGBT.

[0053] In practical applications, the above-mentioned heavy discontinuous mode is also suitable for occasions where the voltage of the filter capacitor needs to be discharged quickly.

[0054] In summary, the driving level adjustment circuit of the power switch provided in the embodiment of the present application effectively limits the current of the IGBT through the low gate driving voltage in the intermittent mode, realizes the energy of the filter capacitor with a small current discharge, and improves the safety and stability of the circuit. When running at low power, the power switch is first turned on at a low voltage to suppress the on-peak current, and then works normally at a high voltage, ensuring the driving capability and power output, and ensuring the reliable operation of the circuit under different working conditions. At the same time, the low gate voltage amplitude of the power switch can be set by a resistor to adapt to the parameters of different power switches, thereby improving the versatility of the circuit. In addition, the circuit can flexibly adjust the delay time of the delay module according to the power size to meet different application requirements. The drive voltage selection in different modes is realized through the EN pin, so that the circuit can be flexibly adjusted under different working conditions, further improving the performance and efficiency of the system.

[0055] It should be noted that the driving level adjustment circuit of the power switch in the above embodiment is only a preferred circuit structure for achieving the purpose of the present invention. In other embodiments, each circuit module or device may also use other circuit structures that can achieve the same function, and the present application is not limited thereto.

[0056] In addition, the embodiment of the present application also provides a power conversion system, including a drive level adjustment circuit of a power switch as in the above embodiment, for meeting the requirements of different working modes and power switches. For the circuit structure and working process not described in detail in the power conversion system of this embodiment, reference can be made to the relevant parts in the above embodiment of the drive level adjustment circuit of the power switch, which will not be repeated here.

[0057] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A driving level adjustment circuit for a power switch, characterized in that: include: Resonance module, which performs electromagnetic heating or power conversion based on the LC parallel resonance principle; A power switch connected to the resonance module and used to adjust the working mode of the resonance module, including a ZVS continuous mode and a discontinuous mode; A driving module, connected to the power switch, and configured to output a driving voltage signal Gate to the power switch to control the on / off state and the low-voltage and high-voltage working states of the power switch; A microcontrol unit is connected to the driving module and is used to output an enable signal EN and a switch signal SW to the driving module, wherein the enable signal EN adjusts the drive voltage signal Gate output by the driving module according to the working mode of the resonance module to control the state of the power switch in the ZVS continuous mode or the discontinuous mode; and the switch signal SW adjusts the drive voltage signal Gate of the power switch through the driving module to control the on / off state and the low-voltage and high-voltage working states of the power switch.

2. The driving level adjustment circuit of the power switch according to claim 1, characterized in that: The working modes of the resonance module include ZVS continuous mode and discontinuous mode; When the resonant module operates in the ZVS continuous mode, the enable signal EN=L=0, and the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch operates in a high voltage state; When the resonance module operates in the discontinuous mode, the enable signal EN=H=1. When the power switch is turned on, the driving module first outputs a low driving voltage signal Gate to the power switch to turn on the power switch in a low voltage state. Then, after a preset time, the driving module outputs a high driving voltage signal Gate to the power switch to enable the power switch to work normally in a high voltage state.

3. The driving level adjustment circuit of the power switch according to claim 2, characterized in that: The driving module includes a delay module TD, an AND gate AND, a second NOT gate INV2 and an OR gate OR; wherein, The input end of the delay module TD is connected to the switch signal SW, and the output end thereof is connected to one input end of the AND gate AND; the other input end of the AND gate AND is connected to the enable signal EN, and the output end of the AND gate AND is connected to the first input end of the OR gate OR; the switch signal SW is connected to the second input end of the OR gate OR after passing through the second NOT gate INV2, and the output end of the OR gate OR outputs the control signal S.

4. The driving level adjustment circuit of the power switch according to claim 1, characterized in that: The working modes of the resonance module include ZVS continuous mode, light discontinuous mode and heavy discontinuous mode, and the enable signal EN includes EN_H and EN_L; When the resonant module operates in the ZVS continuous mode, the enable signal EN_H=0 and EN_L=0, and the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch operates in a high voltage state; When the resonant module operates in the light discontinuous mode, the enable signal EN_H=1 and EN_L=0, and when the power switch is turned on, the driving module first outputs a low driving voltage signal Gate to the power switch, so that the power switch is turned on in a low voltage state, and then after a preset time, the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch works normally in a high voltage state; When the resonance module operates in the heavy discontinuous mode, the enable signal EN_H=0 and EN_L=1, and the driving module outputs a low driving voltage signal Gate to the power switch, so that the power switch operates in a low voltage state.

5. The driving level adjustment circuit of the power switch according to claim 4, characterized in that: The driving module includes a delay module TD, an AND gate AND, a second NOT gate INV2 and an OR gate OR; wherein, The input end of the delay module TD is connected to the switch signal SW, and the output end thereof is connected to one input end of the AND gate AND; the other input end of the AND gate AND is connected to the enable signal EN_H, and the output end of the AND gate AND is connected to the first input end of the OR gate OR; the switch signal SW is connected to the second input end of the OR gate OR after passing through the second NOT gate INV2; the enable signal EN_L is connected to the third input end of the OR gate OR; the output end of the OR gate OR outputs the control signal S.

6. The driving level adjustment circuit of the power switch according to claim 3 or 5, characterized in that: The driving module further includes a current source I, a first resistor R1, a second resistor R2, a first switch K1, a second switch K2, a first switch tube M1, a second switch tube M2, a first NOT gate INV1 and a follower Buffer; wherein, The power supply voltage VCC is grounded via the current source I and the second resistor R2 in sequence; the power supply voltage VCC is also grounded via the first switch tube M1 and the first resistor R1 in sequence; the power supply voltage VCC is also grounded via the second switch tube M2 and the second switch K2 in sequence; the positive input end of the follower Buffer is connected to the node A between the current source I and the second resistor R2, the current output end of the first switch tube M1 is connected to the current output end of the second switch tube M2 and is connected to the reverse input end of the follower Buffer, and serves as the output end of the driving voltage signal Gate; the control end of the first switch tube M1 is connected to the output end of the follower Buffer, and the control end of the second switch tube M2 is connected to the control signal S; the switch signal SW is also connected to the control end of the first switch K1 and the control end of the second switch K2 respectively after passing through the first NOT gate INV1.

7. The driving level adjustment circuit of the power switch according to claim 6, characterized in that: The second resistor R2 is an externally connected adjustable resistor, which is used to generate a driving low voltage VA, and the amplitude of the driving low voltage VA is proportional to the resistance value of the second resistor R2.

8. The driving level adjustment circuit of the power switch according to claim 7, characterized in that: The power switch is an IGBT tube, the first switch tube M1 is an NMOS tube, and the second switch tube M2 is a PMOS tube.

9. The driving level adjustment circuit of the power switch according to claim 6, characterized in that: The preset duration of the delay module TD is set to be greater than 3 μs and less than the minimum on-time of the switch signal SW.

10. The driving level adjustment circuit of a power switch according to any one of claims 7 to 9, characterized in that: When the working mode of the resonance module is the ZVS continuous mode and the discontinuous mode, it includes: When the resonant module works in the ZVS continuous mode, the micro control unit outputs an enable signal EN=L=0; when the switch signal SW is at a high level, the drive voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage working state; when the switch signal SW is at a low level, the drive voltage signal Gate is pulled low, and the power switch is turned off; When the resonance module operates in the discontinuous mode, the micro control unit outputs an enable signal EN=H=1; when the switch signal SW changes from a low level to a high level, the driving voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset time length of the delay module TD, and the power switch is in a low-voltage working state; when the preset time length of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is turned into a high-voltage working state; when the switch signal SW changes from a high level to a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off.

11. The driving level adjustment circuit of a power switch according to any one of claims 7 to 9, characterized in that: When the working mode of the resonance module is the ZVS continuous mode, the light discontinuous mode and the heavy discontinuous mode, it includes: When the resonant module works in the ZVS continuous mode, the micro control unit outputs the enable signal EN_H=0 and EN_L=0; when the switch signal SW is at a high level, the drive voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage working state; when the switch signal SW is at a low level, the drive voltage signal Gate is pulled low, and the power switch is turned off; When the resonance module works in the light discontinuous mode, the micro control unit outputs an enable signal EN_H=1 and EN_L=0; when the switch signal SW changes from a low level to a high level, the driving voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset time length td of the delay module TD, and the power switch is in a low-voltage working state; when the preset time length td of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is turned into a high-voltage working state; when the switch signal SW changes from a high level to a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off; When the resonance module works in the heavy discontinuous mode, the micro control unit outputs an enable signal EN_H=0 and EN_L=1; the driving module outputs VA as a low driving voltage signal Gate to the power switch, and the power switch is in a low voltage working state.

12. The driving level adjustment circuit of a power switch according to any one of claims 7 to 9, characterized in that: The driving level adjustment circuit further includes: A rectifier module, used for rectifying the input grid voltage; A filtering module, used for filtering the rectified voltage; The power supply module is used to provide 18V high voltage for the power switch and 5V low voltage for the micro control unit.

13. A power conversion system, characterized in that: A drive level adjustment circuit comprising a power switch as claimed in any one of claims 1 to 12.

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