A driving level adjustment circuit for a power switch and a power conversion system

Abstract

The present application discloses a driving level adjustment circuit for a power switch and a power conversion system, relating to the field of circuit design. The circuit includes a resonance module that performs electromagnetic heating or power conversion based on the principle of LC parallel resonance; a power switch that adjusts the working mode of the resonance module; a driving module that outputs a driving voltage signal Gate to the power switch to control the opening and closing of the power switch and its low-voltage and high-voltage working states; and a micro control unit that outputs an enable signal EN and a switching signal SW. The enable signal EN adjusts the driving voltage signal Gate 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. The switching signal SW adjusts the driving voltage signal Gate through the driving module to control the state of the power switch. This solution effectively controls the surge current by adjusting the driving voltage of the power switch, can meet the requirements of different working modes and power switches, and improves the adaptability of the system.

Description

Technical Field

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

[0002] The LC parallel resonance circuit is widely used in kilowatt-level power conversion systems because it is easy to achieve ZVS (Zero Voltage Switching). For example, in an induction cooker, a high-frequency alternating current is generated through the LC parallel resonance circuit to drive the coil disk to generate a changing magnetic field, so that eddy currents are generated inside the cookware to achieve heating. The following takes the induction cooker as an example for relevant introduction.

[0003] As Figure 1 shown, the heating system of the existing induction cooker mainly consists of a resonance module (L2, C2), a driving module, a power switch, and a micro control 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 switching noise, a filtering module (L1, C1) is usually provided at the system input end, and the resonance module obtains energy through the low-impedance C1. However, when the resonance 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 inrush current will be generated when the power switch (such as IGBT) conducts, which will impact the IGBT and reduce its reliability. After the initial pulse, the system enters the ZVS state and the inrush current disappears. However, as the load decreases, the system gradually exits the ZVS mode and the inrush current increases again, thus limiting the minimum load power for the system to operate safely. Although the discontinuous operation mode with low valley bottom voltage turn-on can reduce the inrush current, after each pulse stops, C1 will be charged to the peak voltage again, resulting in the reappearance of the inrush current when restarting.

[0004] In order to suppress the inrush current under various working conditions, the industry has proposed a method of controlling the inrush current by adjusting the driving voltage of the power switch. This method reduces the driving voltage to the under-saturated gate voltage level when the power switch is initially turned on or restored to turn on, thereby forcibly reducing the turn-on current. However, due to the differences in the under-saturated 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 driving circuit for power switches to meet the inrush current limit conditions for using different power switches. Summary of the Invention

[0005] The object 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 inrush 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 solutions:

[0007] On the one hand, the present invention provides a driving level adjustment circuit for a power switch, including:

[0008] A resonance module that performs electromagnetic heating or power conversion based on the principle of LC parallel resonance;

[0009] A power switch connected to the resonance module for adjusting the working mode of the resonance module, including ZVS continuous mode and discontinuous mode;

[0010] A driving module connected to the power switch for outputting a driving voltage signal Gate to the power switch to control the opening and closing state and the low-voltage and high-voltage working states of the power switch;

[0011] A micro control unit connected to the driving module for outputting an enable signal EN and a switch signal SW to the driving module. The enable signal EN adjusts the driving 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 discontinuous mode; the switch signal SW adjusts the driving voltage signal Gate of the power switch through the driving module to control the opening and closing state and the low-voltage and high-voltage working states of the power switch.

[0012] Optionally, in the above driving level adjustment circuit for a power switch, the working mode of the resonance module includes ZVS continuous mode and discontinuous mode;

[0013] When the resonance module works 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 to make the power switch work in the high-voltage state;

[0014] When the resonance module works 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 make the power switch turn on in the low-voltage state, and then after a preset time period, the driving module outputs a high driving voltage signal Gate to the power switch to make the power switch work normally in the high-voltage state.

[0015] Optionally, in the above 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,

[0016] 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 inverter INV2, and the output end of the OR gate OR outputs a control signal S.

[0017] Optionally, in the above driving level adjustment circuit of the power switch, the working modes of the resonant module include ZVS continuous mode, light discontinuous mode, and heavy discontinuous mode, and the enable signal EN includes EN_H and EN_L;

[0018] 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;

[0019] When the resonant module operates in the light discontinuous mode, the enable signal EN_H = 1 and EN_L = 0. 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, and 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 operate normally in a high-voltage state;

[0020] When the resonant 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.

[0021] Optionally, in the above driving level adjustment circuit of the power switch, the driving module includes a delay module TD, an AND gate AND, a second inverter INV2, and an OR gate OR; among them,

[0022] 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 inverter 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 a control signal S.

[0023] Furthermore, in the above-mentioned driving level adjustment circuit of the power switch, 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 switching transistor M1, a second switching transistor M2, a first NOT gate INV1, and a follower Buffer; wherein,

[0024] The power supply voltage VCC is grounded through the current source I and the second resistor R2 in sequence; the power supply voltage VCC is also grounded through the first switching transistor M1 and the first resistor R1 in sequence; the power supply voltage VCC is also grounded through the second switching transistor 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 terminals of the first switching transistor M1 and the second switching transistor M2 are connected and connected to the negative input terminal of the follower Buffer, and serve as the output terminal of the driving voltage signal Gate; the control terminal of the first switching transistor M1 is connected to the output terminal of the follower Buffer, the control terminal of the second switching transistor M2 is connected to the control signal S; the switching signal SW is also connected to the control terminals of the first switch K1 and the second switch K2 after passing through the first NOT gate INV1.

[0025] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the second resistor R2 is an externally 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.

[0026] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, the power switch is an IGBT transistor, the first switching transistor M1 is an NMOS transistor, and the second switching transistor M2 is a PMOS transistor.

[0027] 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 3 μs and less than the minimum turn-on duration of the switching signal SW.

[0028] Optionally, in the above-mentioned driving level adjustment circuit of the power switch, when the operating modes of the resonant module include ZVS continuous mode and discontinuous mode:

[0029] When the resonant module operates in the ZVS continuous mode, the micro control unit outputs an enable signal EN = L = 0; when the switching signal SW is at a high level, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage operating state; when the switching signal SW is at a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off;

[0030] When the resonant module operates in the discontinuous mode, the microcontroller unit outputs an enable signal EN = H = 1; when the switch signal SW transitions from a low level to a high level, the driving voltage signal Gate accesses the voltage VA of the first resistor R1 within the preset duration of the delay module TD, and the power switch is in a low-voltage operating state; when the preset duration of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch transitions to a high-voltage operating 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.

[0031] Optionally, for the above driving level adjustment circuit of the power switch, when the operating modes of the resonant module include the ZVS continuous mode, the light discontinuous mode, and the heavy discontinuous mode:

[0032] When the resonant module operates in the ZVS continuous mode, the microcontroller unit outputs enable signals EN_H = 0 and EN_L = 0; 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 is in a high-voltage operating state; when the switch signal SW is at a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off;

[0033] When the resonant module operates in the light discontinuous mode, the microcontroller unit outputs enable signals EN_H = 1 and EN_L = 0; when the switch signal SW transitions from a low level to a high level, the driving voltage signal Gate accesses the voltage VA of the first resistor R1 within the preset duration td of the delay module TD, and the power switch is in a low-voltage operating state; when the preset duration td of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch transitions to a high-voltage operating 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.

[0034] When the resonant module operates in the heavy discontinuous mode, the microcontroller unit outputs enable signals 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 operating state.

[0035] Optionally, for the above driving level adjustment circuit of the power switch, the driving level adjustment circuit further includes:

[0036] A rectification module for rectifying the input grid voltage;

[0037] A filtering module for filtering the rectified voltage;

[0038] A power supply module is used to provide 18V high voltage for the power switch and 5V low voltage for the micro control unit.

[0039] On the other hand, the present invention provides a power conversion system, including a driving level adjustment circuit for the power switch as described in the first aspect.

[0040] The effects provided in the summary of the invention are only the effects of the embodiments, rather than all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects:

[0041] A driving level adjustment circuit for a power switch and a power conversion system provided by the present application include a resonance module, a power switch, a driving module, and a micro control unit in the driving level adjustment circuit. The resonance module performs electromagnetic heating or power conversion based on the LC parallel resonance principle; 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 opening and closing states and low-voltage and high-voltage working states; the micro control unit adjusts the output of the driving module by outputting an enable signal EN and a switching signal SW, so that the driving voltage signal Gate adapts to different working modes. Through the collaborative work of each module unit, this solution realizes flexible adjustment of the driving voltage of the power switch, effectively controls the surge current, meets the requirements of different working modes and power switches, and improves the adaptability and reliability of the system. Description of the Drawings

[0042] The drawings here are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0043] Figure 1 is the schematic diagram of the heating system of an induction cooker in the prior art;

[0044] Figure 2 are the output characteristic curves of four different types of IGBTs;

[0045] Figure 3 is the schematic diagram of the structure of a driving level adjustment circuit for a power switch according to an embodiment of the present application;

[0046] Figure 4 is Figure 3 a logic control circuit diagram of the driving module in

[0047] Figure 5 is Figure 3 another logic control circuit diagram of the driving module in

[0048] Figure 6 is Figure 3 a schematic diagram of the circuit implementation of the driving module in

[0049] Figure 7 For Figure 6 a waveform schematic diagram of the switching signal SW and the driving voltage signal Gate in Specific embodiments

[0050] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to 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 used to limit the present invention.

[0051] It should be noted that the references to "one embodiment", "embodiment", "example embodiment", etc. in this specification mean that the described embodiment may include specific features, structures or characteristics. However, not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Further, when combining embodiments to describe specific features, structures or characteristics, it has been shown that it is within the knowledge of those skilled in the art to combine such features, structures or characteristics into other embodiments whether or not there is an explicit description.

[0052] As described in the background art, the LC parallel resonance circuit is widely used in power conversion systems because it is easy to achieve ZVS. For the sake of convenience of description, 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 adopting the LC parallel resonance method and are not limited to the application of induction cookers.

[0053] Refer to Figure 1 As shown, the heating system of the existing induction cooker mainly includes a rectification module (D11, D12, D13, D14), a filtering module (L1, C1), a resonance module 110, a power switch 120 (taking IGBT as an example hereinafter), a driving module 130, a micro control unit 140 and a power supply module. During the working process, the micro control unit 140 controls the driving module 130 to provide a conduction signal and a driving voltage for the IGBT, so that the resonance module 110 generates a resonance current, and a periodically changing magnetic field is generated in the coil disk to achieve heating of the load.

[0054] When the system operates 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 sinusoidal 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 zero-crossing moment of LC resonance in each switching cycle, so that the IGBT starts in the ZVS mode. When the system operates 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 the dead time). As the power of the system 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 discharge and will maintain the highest voltage after input AC rectification (such as 310V when the input is AC220V). At this time, even if the micro-control unit 140 controls the drive module 130 to turn on the IGBT at the zero-crossing moment of the AC voltage, since the 310V voltage on the filter capacitor C1 is applied to the IGBT, the IGBT turns on in a hard-switching manner, and a large current of up to more than 200A may be generated instantaneously. This large current will cause serious impact on the IGBT, reduce its reliability, and may even cause damage.

[0055] The power supply 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 supply power to the micro-control unit 140 and other modules. When the system operates in low-power discontinuous mode, a large inrush current will be generated when the IGBT is turned on after the dead time. To reduce this inrush current, a dedicated IGBT drive IC is provided in the prior art to control the current magnitude of the IGBT by reducing the gate voltage of the IGBT, and usually limits the current to about 20 - 25A. Taking the IHW20N135R3 type IGBT as an example, when the applied gate drive voltage is 9V, the current capacity of its collector is 20 - 30A, and the inrush current is significantly reduced compared with the condition of an 18V drive voltage. However, this method still has certain deficiencies, that is, once the IGBT model is selected, its gate voltage is difficult to adjust, resulting in inability to meet the requirements of other IGBT models. As Figure 2 shown, for the output characteristic curves of four different types of IGBTs, when their saturation currents are between 20 - 30A, the corresponding V GE voltages are different, such as 9V, 10V, 11V, etc., and even more other voltage parameters. If the voltage setting in the drive IC is fixed, it will be difficult to be compatible with different types of IGBTs. To solve this problem, the embodiments of the present application provide a drive level adjustment circuit and system for a power switch, which can flexibly adjust the drive voltage according to the characteristics of different types of IGBTs in the low-power discontinuous working mode, so as to better control the inrush current and improve the adaptability and reliability of the system.

[0056] 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 operating 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.

[0057] Reference Figure 3 , Figure 3 shows a schematic structural diagram of a driving level adjustment circuit for a power switch according to an embodiment of the present application. The circuit includes a resonance module 210, a power switch 220, a driving module 230, and a micro control unit 240. Among them, the resonance module 210 is based on the LC parallel resonance principle and performs electromagnetic heating or power conversion on the load by generating a resonance current; the power switch 220 is connected to the resonance module 210 and is used to adjust the operating 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 opening and closing states of the power switch 220 and its low-voltage and high-voltage operating states; the micro control 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 operating 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 opening and closing states of the power switch 220 and its low-voltage and high-voltage operating states.

[0058] In some embodiments, the operating modes of the resonance module 210 include the ZVS continuous mode and the discontinuous mode. When the resonance module 210 operates in the ZVS continuous mode, the micro control unit 240 outputs the enable signal EN as a low level (EN = L). At this time, the driving module 230 outputs a high driving voltage signal Gate to the power switch 220 to make it operate in the high-voltage state. When the resonance module 210 operates in the discontinuous mode, the micro control unit 240 outputs the enable signal EN as a high level (EN = H). At this time, when the power switch 220 is turned on, the driving module 210 first outputs a low driving voltage signal Gate to the power switch 220 to turn on the power switch 220 in the low-voltage state to limit the conduction current. Then, after a preset time duration, the driving module 210 outputs a high driving voltage signal Gate to the power switch 220 to make the power switch 220 operate normally in the high-voltage state.

[0059] Figure 4 A Figure 3 logic control circuit diagram of the driving module in the middle. As Figure 4 shown, in this embodiment, the driving module 230 includes a delay module TD, an AND gate AND, a second inverter 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 inverter INV2, and the output end of the OR gate OR outputs a control signal S, and this control signal S is used to adjust the driving voltage signal Gate of the power switch 220.

[0060] In some other embodiments, the working modes of the resonant module 210 include the ZVS continuous mode, the light discontinuous mode, and the heavy discontinuous mode (i.e., the discontinuous mode is further divided into the light discontinuous mode and the heavy discontinuous mode), and the enable signal EN includes EN_H and EN_L. The micro control 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 resonant module 210 works 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 resonant module works in the light discontinuous mode; when the system outputs the minimum power (corresponding to the minimum load), the enable signal is EN_H = 0 and EN_L = 1, and the resonant module works in the heavy discontinuous mode.

[0061] Specifically, 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, the driving module 230 outputs a high driving voltage signal Gate to the power switch 220, so that it works in a high voltage state. 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 a low driving voltage signal Gate to the power switch 220, so that it works in a low voltage state to limit the working current. When the resonant 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 power switch 220 is turned on, the driving module 230 first outputs a low driving voltage signal Gate to the power switch 220 to turn it on in a low voltage state to limit the conduction current, and then after a preset low voltage duration, the driving module 230 outputs a high driving voltage signal Gate to the power switch 220 to make it work normally in a high voltage state to meet the power requirement.

[0062] Figure 5 A Figure 3Another logic control circuit diagram of the middle drive module. As Figure 5 shown, in this embodiment, the drive module 230 includes a delay module TD, an AND gate AND, a second inverter 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 inverter 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 a control signal S, and this control signal S is used to adjust the drive voltage signal Gate of the power switch 220.

[0063] As can be seen from the above analysis, the drive level adjustment circuit of this embodiment realizes flexible adjustment of the drive voltage of the power switch 220 through the coordinated operation of the resonance module 210, the power switch 220, the drive 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.

[0064] Figure 6 For Figure 3 a circuit implementation schematic diagram of the middle drive module. As Figure 6 shown, the drive module 230 further includes a current source I, a first resistor R1, a second resistor R2, a first switch K1, a second switch K2, a first switching tube M1, a second switching tube M2, a first inverter INV1, and a follower Buffer. Among them, the power supply voltage VCC is grounded through the current source I and the second resistor R2 in sequence; the power supply voltage VCC is also grounded through the first switching tube M1 and the first resistor R1 in sequence; the power supply voltage VCC is also grounded through the second switching 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 switching tube M1 is connected to the current output end of the second switching tube M2 and is connected to the negative input end of the follower Buffer, and is used as the output end of the drive voltage signal Gate; the control end of the first switching tube M1 is connected to the output end of the follower Buffer, and the control end of the second switching tube M2 is connected to the control signal S; the switch signal SW is also connected to the control ends of the first switch K1 and the second switch K2 after passing through the first inverter INV1.

[0065] In this embodiment, the second resistor R2 of the driving module 230 is set as an externally adjustable resistor, and a driving low voltage VA can be generated at its end, and the amplitude of the driving low voltage VA is proportional to the resistance value of the second resistor R2. In practical applications, the voltage at the end of the second resistor R2 can be flexibly adjusted according to requirements, so as to realize the control of the driving voltage of different types of power switches and meet the requirements of different working modes and power switches.

[0066] In some embodiments, the power switch is an IGBT tube to meet the requirements of high power. The first switching tube M1 is an NMOS tube, and the second switching tube M2 is a PMOS tube to achieve fast switching control and efficient voltage drive.

[0067] In some embodiments, the preset duration td of the delay module TD is set to be greater than 3 μs and less than the minimum turn-on duration of the switching signal SW, so as to effectively avoid the slow circuit response caused by too long delay. At the same time, when the switching signal SW switches, the driving 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.

[0068] According to Figure 4 and Figure 6 the circuit structure of, when the working modes of the resonant module are ZVS continuous mode and discontinuous mode, its control method is as follows:

[0069] When the resonant module 210 operates in the ZVS continuous mode, the micro control unit 240 outputs an enable signal EN = L = 0; at this time, when the switching 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 switching signal SW is at a low level, the driving voltage signal Gate is pulled low (grounded), and the power switch 220 is turned off;

[0070] When the resonant module 210 operates in the discontinuous mode, the micro control unit 240 outputs an enable signal EN = H = 1; at this time, when the switching 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 duration td of the delay module TD, and the power switch 220 is in a low-voltage working state; when the preset duration 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 changes to a high-voltage working state; when the switching 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. 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 duration.

[0071] According to Figure 5 and Figure 6For the circuit structure, when the operating mode of the resonant module is ZVS continuous mode, light discontinuous mode, and heavy discontinuous mode, the control method is as follows:

[0072] When the resonant module 210 operates in ZVS continuous mode, the micro-control unit 240 outputs the enable signals EN_H = 0 and EN_L = 0; at this time, 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 220 is in a high-voltage operating state; when the switch signal SW is at a low level, the drive voltage signal Gate is pulled low (grounded), and the power switch 220 is turned off;

[0073] When the resonant module 210 operates in light discontinuous mode, the micro-control unit 240 outputs the enable signals 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 drive voltage signal Gate is connected to the voltage VA of the first resistor R1 within the preset duration td of the delay module TD, and the power switch 220 is in a low-voltage operating state; when the preset duration td of the delay module TD ends, the drive voltage signal Gate is connected to the power supply voltage VCC, and the power switch 220 switches to a high-voltage operating state; when the switch signal SW changes from a high level to a low level, the drive voltage signal Gate is pulled low, and the power switch 220 is turned off;

[0074] When the resonant module 210 operates in heavy discontinuous mode, the micro-control unit 240 outputs the enable signals EN_H = 0 and EN_L = 1; at this time, the drive module 230 outputs VA as the drive voltage signal Gate, and the power switch 220 is in a low-voltage operating state. Therefore, the circuit of this embodiment can further ensure smooth switching and safe operation of different operating modes and different power switches by adjusting the drive voltage and delay duration.

[0075] In addition, in some embodiments, the drive adjustment circuit further includes: a rectification module for rectifying the input grid voltage; a filtering module for filtering the rectified voltage; and 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.

[0076] Figure 7 For Figure 5 and Figure 6 the signal waveform diagram of the drive level adjustment circuit of the power switch in Figure 5 and Figure 6 Next, taking the circuit structure of the drive module in Figure 4 and Figure 6 as an example, its working principle and working process will be further described in detail. Regarding the circuit structure of the drive module in Figure 5 and Figure 6Relevant part of the middle drive module.

[0077] When the system is set to low power (light intermittent mode) output, the microcontroller unit 240 outputs an 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 for a preset duration td. When the delay ends, the output of the delay module TD changes from high level to low level. Within the preset duration td, the output of the delay module TD is high level. At this time, the switch signal SW is also high level. Therefore, the AND gate And outputs a high level, which in turn causes the OR gate OR to output a control signal S as high level, and the second switch tube M2 is cut off. At the same time, when SW is high level, after passing through the first inverter INV1, a low level is output, causing both the first switch K1 and the second switch K2 to be cut off. At this time, the driving voltage terminal (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, by adjusting the resistance value of the second resistor R2, the voltage VA at its end can be adjusted, and the amplitude of VA is proportional to the resistance value. At this time, the follower Buffer transfers 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.

[0078] Therefore, when designing the circuit, only the voltage range of VA needs to be considered. After the IGBT model is determined, the resistance value of the second resistor R2 can be adjusted according to its parameters to set an appropriate VA voltage, thereby limiting the conduction current of the IGBT. Even though the voltage of the filter capacitor is the superposition of the resonant voltage and the rectified mains voltage, since the driving voltage is low at this time, the current flowing through the IGBT can still be controlled within a reasonable range, so as to effectively discharge the voltage on the filter capacitor C1 instantaneously during conduction.

[0079] When the preset duration td of the delay module TD ends, its output flips to low level, causing the output of the AND gate And to also become low level. At this time, the switch signal SW outputs a low level after passing through the second inverter INV2. Since both input terminals of the OR gate OR are low level, the control signal S changes from high level to low level, and the second switch tube M2 conducts. Since M2 conducts and both the first switch K1 and the second switch K2 are cut off, the follower Buffer does not work at this time, and the driving voltage signal Gate is directly connected to the power supply voltage VCC, and the IGBT starts to work under high voltage to meet the power demand.

[0080] When the switch signal SW is at a low level, the output of the second inverter INV2 is at a high level, the control signal S output by the OR gate OR becomes high, and the second switching transistor M2 is turned off. At the same time, after passing through the first inverter INV1, SW outputs a high level, causing both the first switch K1 and the second switch K2 to close, and the Gate voltage is pulled down, thereby turning off the IGBT.

[0081] At the beginning of the next cycle of the switch signal SW, the above steps are repeated. That is, the drive voltage signal Gate is first connected to the adjustable low voltage VA to limit the conduction current of the IGBT. After a preset delay duration td, the drive voltage signal Gate is then 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 due to an instantaneous large current.

[0082] When the system operates in the high-power (ZVS continuous mode), the microcontroller unit 240 outputs the enable signals EN_H = 0 and EN_L = 0. At this time, the AND gate AND outputs a low level, both the first input terminal and the third input terminal of the OR gate OR are 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 at a high level, the output of the second inverter INV2 is at a low level, and at this time the control signal S output by the OR gate OR is at a low level, and the second switching transistor M2 is turned on. At the same time, the first inverter INV1 outputs a low level, both the first switch K1 and the second switch K2 are turned off, and the drive voltage signal Gate is connected to the power supply voltage VCC. At this time, the IGBT operates at a high voltage, and the follower Buffer does not function. When the switch signal SW is at a low level, the AND gate AND still outputs a low level, both the first input terminal and the third input terminal of the OR gate OR are connected to a low level, but since the output of the second inverter INV2 is at a high level, the control signal S output by the OR gate OR becomes high, and the second switching transistor M2 is turned off. At the same time, the first inverter INV1 outputs a high level, causing both the first switch K1 and the second switch K2 to close, and at this time the Gate voltage is pulled down, thereby turning off the IGBT.

[0083] When the system operates in the minimum power (heavy discontinuous mode), the microcontroller unit 240 outputs an enable signal EN_H = 0 and EN_L = 1. At this time, the third input terminal of the OR gate is connected to a high level, and the output control signal S of the OR gate is always at a high level, and the second switching transistor M2 is cut off. When SW is at a high level, after passing through the first inverter INV1, a low level is output, causing both the first switch K1 and the second switch K2 to be cut off. At this time, the voltage signal VA of the first resistor R1 is connected to the Gate terminal. 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 transfers the voltage VA on the second resistor R2 to the first resistor R1, making the drive voltage signal Gate equal to VA, and the voltage value of VA is lower than the power supply voltage VCC. After the IGBT model is determined, the resistance value of the second resistor R2 can be adjusted according to its parameters to set an appropriate VA voltage to limit the conduction current of the IGBT.

[0084] When the switch signal SW changes from a high level to a low level, after passing through the first inverter INV1, SW outputs a high level, causing both the first switch K1 and the second switch K2 to close, and the Gate voltage is pulled low, thereby turning off the IGBT.

[0085] In practical applications, the above heavy discontinuous mode is also applicable to occasions where it is necessary to quickly discharge the voltage of the filter capacitor.

[0086] In summary, the drive level adjustment circuit of the power switch provided by the embodiment of the present application effectively limits the current of the IGBT through a low gate drive voltage in the discontinuous mode, realizes the discharge of the energy of the filter capacitor with a small current, and improves the safety and stability of the circuit. When operating at low power, the power switch is first turned on at a low voltage to suppress the conduction spike current, and then operates normally at a high voltage, ensuring the drive ability 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, improving the versatility of the circuit. In addition, the delay time of the delay module of this circuit can be flexibly adjusted according to the power size to meet different application requirements. The drive voltage selection in different modes is realized through the EN pin, enabling the circuit to be flexibly adjusted under different working conditions, and further improving the performance and efficiency of the system.

[0087] It should be noted that the drive level adjustment circuit of the power switch in the above embodiment is only a preferred circuit structure for realizing the purpose of the present invention. In other embodiments, each circuit module or device can also select other circuit structures that can achieve the same function, and the present application is not limited thereto.

[0088] In addition, an embodiment of the present application further provides a power conversion system, including a driving level adjustment circuit for a power switch as in the above embodiment, which is used to meet 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 may be made to the relevant parts in the embodiment of the driving level adjustment circuit for the power switch above, which will not be elaborated here.

[0089] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall 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 Comprising: A resonance module that performs electromagnetic heating or power conversion based on the principle of LC parallel resonance; A power switch connected to the resonance module for adjusting the working mode of the resonance module, including ZVS continuous mode and discontinuous mode; A drive module connected to the power switch for outputting a drive voltage signal Gate to the power switch to control the on / off state and low / high voltage working states of the power switch; A micro control unit connected to the drive module for outputting an enable signal EN and a switch signal SW to the drive module. The enable signal EN adjusts the drive voltage signal Gate output by the drive module according to the working mode of the resonance module to control the state of the power switch in the ZVS continuous mode or discontinuous mode; the switch signal SW adjusts the drive voltage signal Gate of the power switch through the drive module to control the on / off state and low / high voltage working states of the power switch; 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 resonance module operates in the ZVS continuous mode, the enable signal EN_H = 0 and EN_L = 0, and the drive module outputs a high drive voltage signal Gate to the power switch to make the power switch operate in the high voltage state; When the resonance module operates in the light discontinuous mode, the enable signal EN_H = 1 and EN_L = 0. When the power switch is turned on, the drive module first outputs a low drive voltage signal Gate to the power switch to make the power switch turn on in the low voltage state, and then after a preset time, the drive module outputs a high drive voltage signal Gate to the power switch to make the power switch operate normally in the 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 drive module outputs a low drive voltage signal Gate to the power switch to make the power switch operate in the low voltage state; The drive 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 switching tube M1, a second switching tube M2, a first NOT gate INV1, and a follower Buffer; wherein, The power supply voltage VCC is grounded through the current source I and the second resistor R2 in sequence; the power supply voltage VCC is also grounded through the first switching transistor M1 and the first resistor R1 in sequence; the power supply voltage VCC is also grounded through the second switching transistor 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 switching transistor M1 is connected to the current output terminal of the second switching transistor M2 and is connected to the negative input terminal of the follower Buffer, and serves as the output terminal of the driving voltage signal Gate; the control terminal of the first switching transistor M1 is connected to the output terminal of the follower Buffer, and the control terminal of the second switching transistor M2 is connected to the control signal S; the switching signal SW is also connected to the control terminals of the first switch K1 and the second switch K2 after passing through the first inverter INV1.

2. The driving level adjusting circuit of the power switch according to claim 1, wherein The operating modes of the resonant 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 resonant 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, and then after a preset time period, the driving module outputs a high driving voltage signal Gate to the power switch, so that the power switch operates normally in a high voltage state.

3. The driving level adjusting 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 inverter INV2, and an OR gate OR; wherein, The input terminal of the delay module TD is connected to the switching signal SW, and its output terminal is connected to one input terminal of the AND gate AND; the other input terminal of the AND gate AND is connected to the enable signal EN, and the output terminal of the AND gate AND is connected to the first input terminal of the OR gate OR; the switching signal SW is connected to the second input terminal of the OR gate OR after passing through the second inverter INV2, and the output terminal of the OR gate OR outputs the control signal S.

4. The driving level adjustment circuit of the power switch according to claim 1, wherein, The driving module includes a delay module TD, an AND gate AND, a second inverter INV2, and an OR gate OR; wherein, The input terminal of the delay module TD is connected to the switching signal SW, and its output terminal is connected to one input terminal of the AND gate AND; the other input terminal of the AND gate AND is connected to the enable signal EN_H, and the output terminal of the AND gate AND is connected to the first input terminal of the OR gate OR; the switching signal SW is connected to the second input terminal of the OR gate OR after passing through the second inverter INV2; the enable signal EN_L is connected to the third input terminal of the OR gate OR; the output terminal of the OR gate OR outputs the control signal S.

5. The driving level adjusting circuit of the power switch according to claim 4, characterized in that The second resistor R2 is an externally 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.

6. The driving level adjusting circuit of the power switch according to claim 5, characterized in that The power switch is an IGBT transistor, the first switching transistor M1 is an NMOS transistor, and the second switching transistor M2 is a PMOS transistor.

7. The driving level adjusting circuit of the power switch according to claim 4, 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-duration of the switching signal SW.

8. The driving level adjusting circuit of the power switch according to any one of claims 5-7, characterized in that When the operating mode of the resonant module is the ZVS continuous mode and the discontinuous mode, it includes: When the resonant module operates in the ZVS continuous mode, the micro-control unit outputs an enable signal EN = L = 0; when the switching signal SW is at a high level, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage operating state; when the switching signal SW is at a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off. When the resonant module operates in the discontinuous mode, the micro-control unit outputs an enable signal EN = H = 1; when the switching 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 duration of the delay module TD, and the power switch is in a low-voltage operating state; when the preset duration of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch changes to a high-voltage operating state; when the switching 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.

9. The driving level adjusting circuit of the power switch according to any one of claims 5-7, characterized in that When the operating mode of the resonant module is the ZVS continuous mode, the light discontinuous mode, and the heavy discontinuous mode, it includes: When the resonant module operates in the ZVS continuous mode, the micro-control unit outputs an enable signal EN_H = 0 and EN_L = 0; when the switching signal SW is at a high level, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch is in a high-voltage operating state; when the switching signal SW is at a low level, the driving voltage signal Gate is pulled low, and the power switch is turned off. When the resonant module operates in the light discontinuous mode, the micro-control unit outputs an enable signal EN_H = 1 and EN_L = 0; when the switching 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 duration td of the delay module TD, and the power switch is in a low-voltage operating state; when the preset duration td of the delay module TD ends, the driving voltage signal Gate is connected to the power supply voltage VCC, and the power switch changes to a high-voltage operating state; when the switching 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 resonant module operates 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 operating state.

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

11. A power conversion system, characterized in that, It includes a driving level adjustment circuit for the power switch as described in any one of claims 1 to 10.

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