An isolated drive circuit for a half-bridge IGBT module

Abstract

The utility model discloses a kind of isolated drive circuit of half-bridge IGBT module.The circuit includes input module, transformer module, upper tube drive module and lower tube drive module;Input module is used to input alternating voltage;The input end of transformer module is connected with the output end of input module, and the output end of transformer module is connected with the lower tube drive module of upper tube drive module respectively;Transformer module is used to change the size of alternating voltage and provide electrical isolation;Upper tube drive module and lower tube drive module all include signal input unit, opto-isolator isolation unit and switch tube;Opto-isolator isolation unit is located between signal input unit and switch tube, for signal input unit and switch tube are electrically isolated.The circuit recorded in the utility model uses transformer module and opto-isolator isolation unit to ensure that high-voltage side and low-voltage side are completely electrically isolated, effectively prevent the influence of high voltage to low-voltage side, make circuit have higher electrical isolation safety, to improve the safety, stability and reliability of system.

Description

Technical Field

[0001] This utility model relates to the field of power semiconductor module driving, and in particular to an isolation driving circuit for a half-bridge IGBT module. Background Technology

[0002] An insulated-gate bipolar transistor (IGBT) is a composite, fully controllable, voltage-driven power semiconductor device widely used in power electronics. It combines the high input impedance and fast switching characteristics of a MOSFET with the low on-state voltage drop of a bipolar transistor, thus offering significant advantages in medium-to-high frequency, high-power applications.

[0003] The function of the driver circuit is to provide the IGBT with the appropriate gate drive signal to ensure its normal operation. In traditional IGBT driver circuits, there is no effective isolation between the high-voltage and low-voltage sides, or isolation relies on a single optocoupler. This can pose serious safety hazards in high-voltage environments, such as leakage and breakdown, thus affecting the safety and reliability of the system. Furthermore, traditional IGBT driver circuits are prone to failure in complex operating environments, especially in high-temperature, high-humidity, or strong electromagnetic interference environments, affecting the stable operation of the system. Simultaneously, some existing driver circuit designs are not optimized enough, resulting in low energy conversion efficiency, increased system energy consumption, and potentially excessive heat generation, affecting system performance.

[0004] In the process of realizing this utility model, the inventors discovered that the prior art has at least the following problems:

[0005] Existing IGBT drive circuits affect the reliability and stability of the system. Utility Model Content

[0006] The purpose of this invention is to provide an isolated drive circuit for a half-bridge IGBT module, thereby solving the technical problem that existing IGBT drive circuits can affect the reliability and stability of the system. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This utility model provides an isolation drive circuit for a half-bridge IGBT module, comprising: an input module, a transformer module, an upper IGBT drive module, and a lower IGBT drive module;

[0009] The input module is used to input AC voltage;

[0010] The input terminal of the transformer module is connected to the output terminal of the input module, and the output terminal of the transformer module is connected to the lower tube drive module of the upper tube drive module respectively; the transformer module is used to change the magnitude of the AC voltage and provide electrical isolation.

[0011] Both the upper-side drive module and the lower-side drive module include a signal input unit, an optocoupler isolation unit, and a switching transistor; the optocoupler isolation unit is located between the signal input unit and the switching transistor, and is used to electrically isolate the signal input unit and the switching transistor; wherein, the switching transistor in the upper-side drive module is connected to the switching transistor in the lower-side drive module.

[0012] Optionally, the upper tube drive module and the lower tube drive module further include a rectifier unit, which is connected to the output terminal of the transformer module and is used to convert the AC power output by the transformer module into DC power for use by the switching tube.

[0013] Optionally, the upper transistor drive module and the lower transistor drive module further include a step-down unit; the input terminal of the step-down unit is connected to the output terminal of the rectifier unit, and is used to step down the DC power output by the rectifier unit; the output terminal of the step-down unit is connected to the optocoupler isolation unit and the switching transistor respectively.

[0014] Optionally, the upper MOSFET drive module and the lower MOSFET drive module further include an LC filter unit, which is connected to the output terminal of the buck unit and is used to reduce high-frequency noise and ripple in the output voltage of the buck unit.

[0015] Optionally, the upper transistor drive module and the lower transistor drive module further include an RC filter circuit, which includes a resistor and a capacitor, both of which are connected in parallel in the circuit between the collector and emitter of the switching transistor.

[0016] Optionally, the upper transistor driving module further includes transistors Q3, Q1, and Q4; the base of transistor Q3 is connected to the output terminal of the signal input unit, and the collector is connected to the input terminal of the optocoupler isolation unit; the base of transistor Q1 is connected to both the output terminal of the optocoupler isolation unit and the base of transistor Q4, the collector is connected to the output terminal of the buck converter, and the emitter is connected to the gate of the switching transistor; the emitter of transistor Q4 is also connected to the gate of the switching transistor.

[0017] Optionally, the upper transistor drive module includes a bootstrap unit, the input terminal of which is connected to the output terminal of the buck unit and the collector of the transistor Q1, and the output terminal is grounded.

[0018] Optionally, the lower transistor driving module further includes transistors Q7, Q5, and Q8; the base of transistor Q7 is connected to the output terminal of the signal input unit, and the collector is connected to the input terminal of the optocoupler isolation unit; the base of transistor Q5 is connected to both the output terminal of the optocoupler isolation unit and the base of transistor Q8, the collector is connected to the output terminal of the buck unit, and the emitter is connected to the gate of the switching transistor; the emitter of transistor Q8 is also connected to the gate of the switching transistor.

[0019] Optionally, the transformer module is a transformer, and the turns ratio of the primary coil to the secondary coil of the transformer is 10:1.

[0020] Optionally, the input module includes a fuse for providing overcurrent protection.

[0021] Implementing one of the above-described technical solutions of this utility model has the following advantages or beneficial effects:

[0022] The isolation drive circuit of the half-bridge IGBT module described in this utility model includes an input module, a transformer module, an upper IGBT drive module, and a lower IGBT drive module. Both the upper and lower IGBT drive modules include a signal input unit, an optocoupler isolation unit, and a switching transistor. The circuit uses a transformer module and an optocoupler isolation unit to ensure complete electrical isolation between the high-voltage and low-voltage sides, effectively preventing the influence of high voltage on the low-voltage side, thus providing higher electrical isolation safety and improving the system's safety, stability, and reliability. Multiple protection mechanisms are also introduced, such as fuse F1 for overcurrent protection and a bootstrap unit to ensure the normal operation of the upper IGBT Q2. Furthermore, the circuit structure is simplified, making the isolation drive circuit described in this utility model more adaptable and flexible to meet the application requirements of different power levels. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0024] Figure 1 This is a schematic diagram of the circuit structure of an embodiment of the present utility model;

[0025] In the diagram: 1. Input module; 2. Transformer module; 3. Upper transistor drive module; 31. Bootstrap unit; 4. Lower transistor drive module; 41. Signal input unit; 42. Optocoupler isolation unit; 43. Switching transistor; 44. Rectifier unit; 45. Buck unit; 46. LC filter unit; 47. RC filter circuit. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, various exemplary embodiments described below will be referenced to the accompanying drawings, which form part of the exemplary embodiments, illustrating various exemplary embodiments that may be adopted to implement this utility model. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. It should be understood that they are merely examples of processes, methods, and apparatuses consistent with some aspects of this utility model disclosed as detailed in the appended claims, and other embodiments may be used, or structural and functional modifications may be made to the embodiments listed herein without departing from the scope and spirit of this utility model.

[0027] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the referred element must have a specific orientation, or be constructed and operated in a specific orientation. The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. The term "multiple" means two or more. The terms "connected" and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, integral connections, mechanical connections, electrical connections, communication connections, direct connections, indirect connections through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more of the related listed items. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0028] To illustrate the technical solution described in this utility model, specific embodiments are described below, showing only the parts related to the embodiments of this utility model.

[0029] Example:

[0030] like Figure 1As shown, this utility model provides an isolation drive circuit for a half-bridge IGBT module, including: an input module 1, a transformer module 2, an upper transistor drive module 3, and a lower transistor drive module 4; the input module 1 is used to input AC voltage; the input terminal of the transformer module 2 is connected to the output terminal of the input module 1, and the output terminal of the transformer module 2 is connected to the lower transistor drive module 4 of the upper transistor drive module 3; the transformer module 2 is used to change the magnitude of the AC voltage and provide electrical isolation; both the upper transistor drive module 3 and the lower transistor drive module 4 include a signal input unit 41, an optocoupler isolation unit 42, and a switch 43; the optocoupler isolation unit 42 is located between the signal input unit 41 and the switch 43, and is used to electrically isolate the signal input unit 41 and the switch 43; wherein, the switch 43 in the upper transistor drive module 3 and the switch 43 in the lower transistor drive module 4 are connected to form a half-bridge IGBT module.

[0031] Specifically, the isolation drive circuit of the half-bridge IGBT module described in this embodiment mainly includes an input module 1, a transformer module 2, an upper IGBT drive module 3, and a lower IGBT drive module 4. The transformer module 2 is located between the input module 1 and the upper and lower IGBT drive modules 3 and 4, and is used to achieve electrical isolation between the input module 1 and these modules. Meanwhile, both the upper and lower IGBT drive modules 3 and 4 include a signal input unit 41, an optocoupler isolation unit 42, and a switching transistor 43. The optocoupler isolation unit 42 is located between the signal input unit 41 and the switching transistor 43, and is used to achieve electrical isolation between the signal input unit 41 and the switching transistor 43.

[0032] This embodiment employs dual electrical isolation technology (transformer module 2 and optocoupler isolation unit 42) to ensure complete electrical isolation between the high-voltage side and the low-voltage side. This effectively prevents the influence of high voltage on the low-voltage side, reduces the impact of battery interference, enhances the reliability of signal transmission, avoids faults caused by transient voltage, and improves the safety and stability of the system.

[0033] The isolation drive circuit of the half-bridge IGBT module described in this embodiment includes an input module 1, a transformer module 2, an upper IGBT drive module 3, and a lower IGBT drive module 4. The following will describe the process in conjunction with... Figure 1 The isolation drive circuit of the half-bridge IGBT module is described in detail.

[0034] As an optional implementation, input module 1 is used to input AC voltage, and its output terminal is connected to the input terminal of transformer module 2. Input module 1 includes fuse F1. After the AC voltage is input, it will be output to transformer module 2 through fuse F1. Fuse F1 can provide overcurrent protection to prevent the current in the circuit from exceeding the safe range, thereby improving the stability and reliability of the drive circuit.

[0035] As an optional implementation, the input terminal of transformer module 2 is connected to the output terminal of input module 1, and two output terminals are provided, which are respectively connected to the upper tube drive module 3 and the lower tube drive module 4. In this embodiment, transformer module 2 is transformer T1. Transformer T1 provides electrical isolation while changing the magnitude of AC voltage, electrically isolating input module 1 from the upper tube drive module 3 and the lower tube drive module 4.

[0036] Furthermore, the primary to secondary winding of transformer T1 has a turns ratio of 10:1, proportionally converting AC 220V into two AC 22V outputs, which are then fed to the upper transistor drive module 3 and the lower transistor drive module 4 respectively. The first and second pins of transformer T1 are both connected to input module 1; the third and fourth pins serve as the positive and negative terminals of the AC power supply and are connected to the upper transistor drive module 3, while the fifth and sixth pins also serve as the positive and negative terminals of the AC power supply and are connected to the lower transistor drive module 4. It should be noted that transformer T1 in this embodiment can be a dual-secondary transformer.

[0037] As an optional implementation, the isolation drive circuit also includes an upper MOSFET drive module 3 and a lower MOSFET drive module 4, which are described below in conjunction with... Figure 1 The upper tube drive module 3 and the lower tube drive module 4 are described in detail respectively.

[0038] The upper transistor drive module 3 includes a rectifier unit 44, which is connected to the output terminal of the transformer module 2. The rectifier unit 44 converts the AC power output from the transformer module 2 into DC power for use by the switching transistor 43 (IGBT Q2). Specifically, the rectifier unit 44 is connected to the third and fourth pins of the transformer module 2. The rectifier unit 44 includes diodes D2, D3, D6, and D7, which form a full-wave rectifier bridge to convert AC power to DC power. When the AC power supply is in the positive half-cycle, the polarity of the input voltage is positive at the top and negative at the bottom. Current flows through diode D2 to the positive terminal of the load, and then returns from the negative terminal of the load to the negative terminal of the AC power supply through diode D7. When the AC power supply is in the negative half-cycle, the polarity of the input voltage is negative at the top and positive at the bottom. Current flows through diode D3 to the positive terminal of the load, and then returns from the negative terminal of the load to the positive terminal of the AC power supply through diode D6. It should be noted that the voltage output by the rectifier bridge in this embodiment is 22√2V, or approximately 31V.

[0039] The upper transistor drive module 3 also includes a step-down unit 45. The input terminal of the step-down unit 45 is connected to the output terminal of the rectifier unit 44, and is used to step down the DC power output by the rectifier unit 44. The output terminal of the step-down unit 45 is connected to the optocoupler isolation unit 42 and the switching transistor 43 (IGBT Q2). Specifically, the step-down unit 45 is used to step down the AC power output by the rectifier unit 44, reducing the voltage from 31V to 15V. In this embodiment, the step-down unit 45 in the upper transistor drive module 3 is a step-down chip U1, and the model of the step-down chip U1 can be selected as XL2596.

[0040] The first pin of the step-down chip U1 is the input pin, which is connected to the output of the transformer unit; the second pin is the output pin, which is connected to the optocoupler isolation unit 42 and the IGBT transistor Q2; the fourth pin is the feedback pin; and the third, fifth and sixth pins are all grounded.

[0041] Capacitors C1 and C2 are connected in parallel on the circuits of the first, third, fifth, and sixth pins of the step-down chip U1. Capacitor C1 is used to filter out low-frequency noise and ripple. In this embodiment, capacitor C1 can be an electrolytic capacitor. Electrolytic capacitors have a larger capacitance, which can smooth voltage fluctuations over a wider frequency range, ensuring power supply stability. The capacitance of capacitor C1 can be selected according to actual conditions; in this embodiment, it can be 470μF. Capacitor C2 is used to filter and eliminate high-frequency noise. In this embodiment, capacitor C2 can be a ceramic capacitor. Ceramic capacitors have lower equivalent series resistance (ESR) and equivalent series inductance (ESL), which can effectively suppress high-frequency noise and ripple, ensuring a clean and stable power supply. The capacitance of capacitor C2 can be selected according to actual conditions; in this embodiment, it can be 1μF.

[0042] The fourth, third, fifth and sixth pins of the step-down chip U1 share a common ground. A Zener diode D4 is connected in series in its grounding circuit. The Zener diode D4 stabilizes the output voltage to a certain extent and provides some overvoltage protection. When the output voltage exceeds the set safety value, the Zener diode will conduct and shunt the excess current, thereby preventing other components in the circuit from being damaged due to overvoltage.

[0043] The upper transistor drive module 3 also includes an LC filter unit 46, which is connected to the output terminal of the buck unit 45 and is used to reduce high-frequency noise and ripple in the output voltage of the buck unit 45. Specifically, the filter unit includes an inductor L1, a capacitor C3, and a capacitor C4. The inductor L1 is connected to the second pin of the buck chip U1, and the capacitors C3 and C4 are located at the rear end of the inductor L1 and connected in parallel between the second, third, fifth, and sixth pins of the buck chip U1. The main function of the inductor L1 is to store energy and smooth current fluctuations in the circuit. By limiting the rate of change of current, it reduces the ripple of the output voltage, thereby providing a more stable output voltage for the switching transistor 43. In this embodiment, the inductor L1, capacitor C3, and capacitor C4 work together to form an LC filter to reduce high-frequency noise and ripple in the output voltage, making the output cleaner.

[0044] The upper transistor drive module 3 also includes an RC filter circuit 47, which includes a resistor C6 and a capacitor R4. Both resistor C6 and capacitor R4 are connected in parallel in the collector-emitter circuit of the switching transistor 43. Resistor C6 provides an energy dissipation path, while capacitor R4 stores and releases energy. They work together to maintain circuit stability by absorbing transient energy, slowing the voltage rise rate, and suppressing oscillations. It should be noted that the RC filter circuit 47 in the upper transistor drive module 3 and the RC filter circuit 47 in the lower transistor drive module 4 are connected in series.

[0045] The upper-side drive module 3 also includes a signal input unit 41, an optocoupler isolation unit 42, and a switching transistor 43. The optocoupler isolation unit 42 is located between the signal input unit 41 and the switching transistor 43, and is used to electrically isolate the signal input unit 41 and the switching transistor 43. The upper-side drive module 3 also includes transistors Q3, Q1, and Q4; the base of transistor Q3 is connected to the output terminal of the signal input unit 41, and its collector is connected to the input terminal of the optocoupler isolation unit 42; the base of transistor Q1 is connected to both the output terminal of the optocoupler isolation unit 42 and the base of transistor Q4, its collector is connected to the output terminal of the buck converter 45, and its emitter is connected to the gate of the switching transistor 43; the emitter of transistor Q4 is also connected to the gate of the switching transistor 43. In this embodiment, the signal input unit 41 in the upper-side drive module 3 is used to generate a PWM pulse width modulation signal PWM1; the optocoupler isolation unit 42 is an optocoupler isolation chip U2, and the switching transistor 43 is an IGBT transistor Q2.

[0046] Signal input unit 41 is connected to the base of transistor Q3 via resistor R7. The emitter of transistor Q3 is grounded, and the collector is connected to the second pin of optocoupler isolation chip U2. The first pin of optocoupler isolation chip U2 is connected to the +5V power supply via resistor R1. The third pin of optocoupler isolation chip U2 is grounded. The fourth pin of optocoupler isolation chip U2 is connected to LC filter unit 46 via resistor R2, and to the base of transistor Q1 and the base and collector of transistor Q4 via resistor R3 and diode D5. The collector of transistor Q1 is connected to LC filter unit 46. The emitter of transistor Q1 is connected to the emitter of transistor Q4 and the gate of IGBT Q2 via resistor R5. The gate of IGBT Q2 is also grounded via resistor R17. It should be noted that resistors R1, R2, and R7 in this embodiment are all current-limiting resistors.

[0047] As an optional implementation, the upper-side drive module 3 includes a bootstrap unit 31. The input terminal of the bootstrap unit 31 is connected to the output terminal of the buck unit 45 and the collector of transistor Q1, respectively, and the output terminal is grounded. Specifically, the bootstrap unit 31 includes a diode D1 and a capacitor C5. Diode D1 and capacitor C5 form a bootstrap circuit to provide a high-side floating power supply. When IGBT Q6 is turned on and IGBT Q2 is not turned on, capacitor C5 is charged to 15V through diode D1. When IGBT Q6 is not turned on and IGBT Q2 is turned on, the emitter voltage of IGBT Q2 increases with the increase of the load voltage, and the cathode voltage of diode D1 is higher than the anode voltage. Diode D1 is not turned on. Capacitor C5 provides the required VGS for the high-side switch, ensuring that the high-side switch is turned on normally. Capacitor C5 continues to discharge during the high-side switch conduction period, maintaining the gate-source voltage of the high-side switch until the low-side switch turns on again in the next cycle, recharging capacitor C5.

[0048] The working principle of the upper transistor drive module 3 is as follows: When PWM1 is high, transistor Q3 is turned on, optocoupler isolation chip U2 is turned on, and the voltage reaches ground after passing through resistor R2. Transistor Q1 is not turned on, meaning IGBT Q2 is not turned on. If there is undissipated energy at the gate of IGBT Q2, transistor Q4 will turn on to dissipate it. Resistor R5 is the turn-on resistor for IGBT Q2, and resistor R6 is the turn-off resistor for transistor Q4. Resistor R17 protects the gate and emitter of IGBT Q2 from breakdown. Resistor R8 limits the current to the base and collector of transistor Q4 to prevent parasitic effects. When PWM1 is low, transistor Q3 is not turned on, optocoupler isolation chip U2 is not turned on, transistor Q1 is turned on, transistor Q4 is not turned on, and IGBT Q2 is turned on. Capacitor C6 and resistor R4 form an RC filter circuit 47. Resistor R4 provides an energy dissipation path, while capacitor C6 stores and releases energy. The two work together to maintain circuit stability by absorbing transient energy, slowing down the voltage rise rate, and suppressing oscillations.

[0049] The lower transistor drive module 4 includes a rectifier unit 44, which is connected to the output terminal of the transformer module 2. The rectifier unit 44 converts the AC power output from the transformer module 2 into DC power for use by the switching transistor 43 (IGBT Q6). Specifically, the rectifier unit 44 is connected to the third and fourth pins of the transformer module 2. The rectifier unit 44 includes diodes D8, D9, D12, and D13, which form a full-wave rectifier bridge to convert AC power to DC power. When the AC power supply is in the positive half-cycle, the polarity of the input voltage is positive at the top and negative at the bottom. Current flows through diode D8 to the positive terminal of the load, and then returns from the negative terminal of the load to the negative terminal of the AC power supply through diode D13. When the AC power supply is in the negative half-cycle, the polarity of the input voltage is negative at the top and positive at the bottom. Current flows through diode D9 to the positive terminal of the load, and then returns from the negative terminal of the load to the positive terminal of the AC power supply through diode D12. It should be noted that the voltage output by the rectifier bridge in this embodiment is 22√2V, or approximately 31V.

[0050] The lower transistor drive module 4 also includes a step-down unit 45. The input terminal of the step-down unit 45 is connected to the output terminal of the rectifier unit 44, and is used to step down the DC power output by the rectifier unit 44. The output terminal of the step-down unit 45 is connected to the optocoupler isolation unit 42 and the switching transistor 43 (IGBT Q6). Specifically, the step-down unit 45 is used to step down the AC power output by the rectifier unit 44, reducing the voltage from 31V to 15V. In this embodiment, the step-down unit 45 in the lower transistor drive module 4 is a step-down chip U3, and the model of the step-down chip U3 can be selected as XL2596.

[0051] The first pin of the step-down chip U3 is the input pin, which is connected to the output of the transformer unit; the second pin is the output pin, which is connected to the optocoupler isolation unit 42 and the IGBT transistor Q6; the fourth pin is the feedback pin; and the third, fifth and sixth pins are all grounded.

[0052] Capacitors C7 and C8 are connected in parallel on the circuits of pins 1, 3, 5, and 6 of the step-down chip U3. Capacitor C7 is used to filter out low-frequency noise and ripple. In this embodiment, capacitor C7 can be an electrolytic capacitor. Electrolytic capacitors have a larger capacitance, which can smooth voltage fluctuations over a wider frequency range, ensuring power supply stability. The capacitance of capacitor C7 can be selected according to actual conditions; in this embodiment, it can be 470μF. Capacitor C8 is used to filter and eliminate high-frequency noise. In this embodiment, capacitor C8 can be a ceramic capacitor. Ceramic capacitors have lower equivalent series resistance (ESR) and equivalent series inductance (ESL), which can effectively suppress high-frequency noise and ripple, ensuring a clean and stable power supply. The capacitance of capacitor C8 can be selected according to actual conditions; in this embodiment, it can be 1μF.

[0053] The fourth, third, fifth and sixth pins of the step-down chip U3 share a common ground. A Zener diode D10 is connected in series in its grounding circuit. The Zener diode D10 stabilizes the output voltage to a certain extent and provides some overvoltage protection. When the output voltage exceeds the set safe value, the Zener diode will conduct and shunt the excess current, thereby preventing other components in the circuit from being damaged due to overvoltage.

[0054] The lower transistor drive module 4 also includes an LC filter unit 46, which is connected to the output terminal of the buck unit 45 and is used to reduce high-frequency noise and ripple in the output voltage of the buck unit 45. Specifically, the filter unit includes an inductor L2, a capacitor C9, and a capacitor C10. The inductor L2 is connected to the second pin of the buck chip U3, and the capacitors C9 and C10 are located at the rear end of the inductor L2 and connected in parallel between the second, third, fifth, and sixth pins of the buck chip U3. The main function of the inductor L2 is to store energy and smooth current fluctuations in the circuit. By limiting the rate of change of current, it reduces the ripple of the output voltage, thereby providing a more stable output voltage for the switching transistor 43. In this embodiment, the inductor L2, capacitor C9, and capacitor C10 work together to form an LC filter to reduce high-frequency noise and ripple in the output voltage, making the output cleaner.

[0055] The lower transistor drive module 4 also includes an RC filter circuit 47, which includes a resistor C11 and a capacitor R12. Both resistor C11 and capacitor R12 are connected in parallel in the collector-emitter circuit of the switching transistor 43. Resistor C11 provides an energy dissipation path, while capacitor R12 stores and releases energy. They work together to maintain circuit stability by absorbing transient energy, slowing the voltage rise rate, and suppressing oscillations. It should be noted that the RC filter circuit 47 in the lower transistor drive module 4 is connected in series with other RC filter circuits in the lower transistor drive module 4.

[0056] The lower transistor drive module 4 also includes a signal input unit 41, an optocoupler isolation unit 42, and a switching transistor 43. The optocoupler isolation unit 42 is located between the signal input unit 41 and the switching transistor 43, and is used to electrically isolate the signal input unit 41 and the switching transistor 43. The lower transistor drive module 4 also includes transistors Q7, Q5, and Q16; the base of transistor Q7 is connected to the output terminal of the signal input unit 41, and its collector is connected to the input terminal of the optocoupler isolation unit 42; the base of transistor Q5 is connected to both the output terminal of the optocoupler isolation unit 42 and the base of transistor Q16, its collector is connected to the output terminal of the buck unit 45, and its emitter is connected to the gate of the switching transistor 43; the emitter of transistor Q16 is also connected to the gate of the switching transistor 43. In this embodiment, the signal input unit 41 in the lower transistor drive module 4 is used to generate a PWM pulse width modulation signal PWM1; the optocoupler isolation unit 42 is an optocoupler isolation chip U2, and the switching transistor 43 is an IGBT transistor Q6.

[0057] Signal input unit 41 is connected to the base of transistor Q7 via resistor R15. The emitter of transistor Q7 is grounded, and the collector is connected to the second pin of optocoupler isolation chip U2. The first pin of optocoupler isolation chip U2 is connected to the +5V power supply via resistor R9. The third pin of optocoupler isolation chip U2 is grounded. The fourth pin of optocoupler isolation chip U2 is connected to LC filter unit 46 via resistor R10, and to the base of transistor Q5 and the base and collector of transistor Q16 via resistor R11 and diode D11. The collector of transistor Q5 is connected to LC filter unit 46. The emitter of transistor Q5 is connected to the emitter of transistor Q16 and the gate of IGBT Q6 via resistor R13. The gate of IGBT Q6 is also grounded via resistor R17. It should be noted that resistors R9, R10, and R15 in this embodiment are all current-limiting resistors.

[0058] The working principle of the lower transistor drive module 4 is as follows: When PWM1 is high, transistor Q7 is turned on, optocoupler U2 is turned on, and the voltage reaches ground after passing through resistor R10. Transistor Q5 is not turned on, meaning IGBT Q6 is not turned on. If there is undissipated energy at the gate of IGBT Q6, transistor Q16 will turn on to dissipate it. Resistor R13 is the turn-on resistor for IGBT Q6, and resistor R14 is the turn-off resistor for transistor Q16. Resistor R97 protects the gate and emitter of IGBT Q6 from breakdown. Resistor R16 limits the current to the base and collector of transistor Q16 to prevent parasitic effects. When PWM1 is low, transistor Q7 is not turned on, optocoupler U2 is not turned on, transistor Q5 is turned on, transistor Q16 is not turned on, and IGBT Q6 is turned on. Capacitor C11 and resistor R12 form an RC filter circuit 47. Resistor R12 provides an energy dissipation path, while capacitor C11 stores and releases energy. The two work together to maintain circuit stability by absorbing transient energy, slowing down the voltage rise rate, and suppressing oscillations.

[0059] It should be noted that the driving circuit of IGBT Q6 in this embodiment is the same as that of IGBT Q2. However, since the emitter of IGBT Q6 is grounded, the lower drive module 4 does not need the bootstrap unit 31.

[0060] The isolation drive circuit of the half-bridge IGBT module described in this embodiment includes an input module 1, a transformer module 2, an upper IGBT drive module 3, and a lower IGBT drive module 4. Both the upper IGBT drive module 3 and the lower IGBT drive module 4 include a signal input unit 41, an optocoupler isolation unit 42, and a switching transistor 43. The transformer module 2 and the optocoupler isolation unit 42 are used in the circuit to ensure complete electrical isolation between the high-voltage and low-voltage sides, effectively preventing the influence of high voltage on the low-voltage side, thus providing higher electrical isolation safety and improving the system's safety, stability, and reliability. Multiple protection mechanisms are also introduced, such as a fuse F1 for overcurrent protection and a bootstrap unit 31 to ensure the normal operation of the upper IGBT Q2. Furthermore, the circuit structure is simplified, making the isolation drive circuit described in this embodiment more adaptable and flexible to meet the application requirements of different power levels.

[0061] The embodiment is merely a special case and does not indicate that this utility model is implemented in such a way.

[0062] The above description is merely a preferred embodiment of the present utility model. Those skilled in the art will understand that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present utility model. Furthermore, under the teachings of the present utility model, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present utility model. Therefore, the present utility model is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present utility model.

Claims

1. An isolation drive circuit for a half-bridge IGBT module, characterized in that, include: Input module, transformer module, upper tube drive module, and lower tube drive module; The input module is used to input AC voltage; The input terminal of the transformer module is connected to the output terminal of the input module, and the output terminal of the transformer module is connected to the lower tube drive module of the upper tube drive module respectively; the transformer module is used to change the magnitude of the AC voltage and provide electrical isolation. Both the upper-side drive module and the lower-side drive module include a signal input unit, an optocoupler isolation unit, and a switching transistor; the optocoupler isolation unit is located between the signal input unit and the switching transistor, and is used to electrically isolate the signal input unit and the switching transistor; wherein, the switching transistor in the upper-side drive module is connected to the switching transistor in the lower-side drive module.

2. The isolation drive circuit for the half-bridge IGBT module according to claim 1, characterized in that, The upper tube drive module and the lower tube drive module also include a rectifier unit, which is connected to the output terminal of the transformer module and is used to convert the AC power output by the transformer module into DC power for use by the switching tube.

3. The isolation drive circuit for the half-bridge IGBT module according to claim 2, characterized in that, The upper transistor drive module and the lower transistor drive module also include a step-down unit; the input terminal of the step-down unit is connected to the output terminal of the rectifier unit, and is used to step down the DC power output by the rectifier unit; the output terminal of the step-down unit is connected to the optocoupler isolation unit and the switching transistor respectively.

4. The isolation drive circuit of the half-bridge IGBT module according to claim 3, characterized in that, The upper transistor drive module and the lower transistor drive module also include an LC filter unit, which is connected to the output terminal of the buck unit and is used to reduce high-frequency noise and ripple in the output voltage of the buck unit.

5. The isolation drive circuit for the half-bridge IGBT module according to claim 1, characterized in that, The upper transistor drive module and the lower transistor drive module also include an RC filter circuit. The RC filter circuit includes a resistor and a capacitor, both of which are connected in parallel in the circuit between the collector and emitter of the switching transistor.

6. The isolation drive circuit for the half-bridge IGBT module according to any one of claims 1-5, characterized in that, The upper transistor driving module also includes transistors Q3, Q1, and Q4; the base of transistor Q3 is connected to the output terminal of the signal input unit, and the collector is connected to the input terminal of the optocoupler isolation unit; the base of transistor Q1 is connected to both the output terminal of the optocoupler isolation unit and the base of transistor Q4, the collector is connected to the output terminal of the buck converter, and the emitter is connected to the gate of the switching transistor; the emitter of transistor Q4 is also connected to the gate of the switching transistor.

7. The isolation drive circuit for the half-bridge IGBT module according to claim 6, characterized in that, The upper transistor drive module includes a bootstrap unit. The input terminal of the bootstrap unit is connected to the output terminal of the buck unit and the collector of the transistor Q1, respectively, and the output terminal is grounded.

8. The isolation drive circuit for the half-bridge IGBT module according to any one of claims 1-5, characterized in that, The lower transistor driving module further includes transistors Q7, Q5, and Q8; the base of transistor Q7 is connected to the output terminal of the signal input unit, and the collector is connected to the input terminal of the optocoupler isolation unit; the base of transistor Q5 is connected to both the output terminal of the optocoupler isolation unit and the base of transistor Q8, the collector is connected to the output terminal of the buck unit, and the emitter is connected to the gate of the switching transistor; the emitter of transistor Q8 is also connected to the gate of the switching transistor.

9. The isolation drive circuit for the half-bridge IGBT module according to any one of claims 1-5, characterized in that, The transformer module is a transformer, and the turns ratio of the primary coil to the secondary coil of the transformer is 10:

1.

10. The isolation drive circuit for the half-bridge IGBT module according to any one of claims 1-5, characterized in that, The input module includes a fuse for providing overcurrent protection.

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