Self-powered half-bridge drive circuit

Abstract

The invention discloses a self-power-taking half-bridge driving circuit, which comprises an unsteady multivibrator, an alternating current conversion module, a transformer and a self-power-taking driving module which are connected in sequence, and is characterized in that the unsteady multivibrator is used for generating pulse square wave signals required by driving; the alternating current conversion module is used for converting the pulse square wave signal from the unsteady multivibrator into an alternating current square wave signal; the transformer is used for performing electrical isolation and signal amplification on the alternating current square wave signal from the alternating current conversion module to obtain an amplified alternating current square wave signal; and the self-powered driving module is used for rectifying and delaying the amplified alternating-current square wave signal and amplifying the signal so as to drive the half-bridge circuit. According to the invention, the module is composed of discrete components, only one independent power supply is included, each module can work in a high-temperature environment, the use amount of the power supply is reduced due to a self-power-taking working mode, the heat yield can be better reduced in the high-temperature environment, and the stable operation of the circuit is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics, and in particular relates to a self-powered half-bridge driving circuit. Background Art

[0002] The half-bridge circuit driving solution has occupied an important position in many industrial and electronic application fields due to its simple structural design, significant cost-effectiveness and efficient energy conversion. This solution is particularly critical in motor control systems, and can accurately control the speed and direction of equipment such as DC motors and stepper motors. Especially in the drive control of electric vehicles, by adjusting the duty cycle of the PWM signal, efficient and precise control of the motor is achieved. In the field of power conversion, the half-bridge circuit realizes the conversion of DC to AC and the conversion of different voltage levels through flexible switching control, and is widely used in various power converters and inverters. In addition, in many fields such as industrial automation, switching power supplies, uninterruptible power supply systems (UPS), chargers, energy-saving lamps and LED lighting, the half-bridge circuit driving solution has also demonstrated excellent performance. By optimizing circuit design, improving energy conversion efficiency and enhancing system stability and reliability, it meets the needs of various complex application scenarios and further promotes the development and progress of related industries.

[0003] The driving scheme of the half-bridge circuit usually consists of PWM IC + integrated driver IC or PWM IC + traditional discrete component driver circuit. The PWM IC provides an accurate square wave signal as the driving signal, the integrated driver IC receives the external control signal, and converts the signal into a control signal for the power switching device through the internal circuit. The traditional discrete component driver circuit isolates and amplifies the signal of the PWM IC for the control signal of the power switching device.

[0004] The existing half-bridge circuit driving solution includes a PWM IC as a driving square wave signal generator. However, the silicon-based IC usually has an operating temperature of only 125°C, which cannot meet the temperature requirements of the driving circuit solution. At the same time, the driving solution of PWM IC + integrated driver IC or PWM IC + traditional discrete component driver circuit usually includes one or more power supplies in the PWM IC link and the driver amplifier link, which increases the power consumption while having a lower energy conversion efficiency. The dissipated energy also causes the circuit to rise in temperature. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a self-powered half-bridge driving circuit. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] The present invention provides a self-powered half-bridge driving circuit, comprising an astable multivibrator, an AC conversion module, a transformer and a self-powered driving module connected in sequence, wherein:

[0007] The astable multivibrator is used to generate a pulse square wave signal required for driving;

[0008] The AC conversion module is used to convert the pulse square wave signal from the astable multivibrator into an AC square wave signal;

[0009] The transformer is used to electrically isolate and amplify the AC square wave signal from the AC conversion module to obtain an amplified AC square wave signal;

[0010] The self-powered driving module is used to rectify, delay and amplify the amplified AC square wave signal to drive the half-bridge circuit.

[0011] In one embodiment of the present invention, the astable multivibrator includes a power supply DC, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D1, a diode D2, a capacitor C1, a capacitor C2, an NPN transistor Q1 and an NPN transistor Q2, wherein:

[0012] The first end of the resistor R1, the first end of the resistor R3, the first end of the resistor R7, the first end of the resistor R8, the first end of the resistor R4 and the first end of the resistor R2 are all connected to the positive electrode of the power supply DC, the second end of the resistor R1 is connected to the cathode of the diode D1 and the collector of the NPN transistor Q1, and the resistor R5 is connected between the second end of the resistor R3 and the anode of the diode D1;

[0013] The first end of the capacitor C1 is connected to the anode of the diode D1, the second end of the capacitor C1 is connected to the base of the NPN transistor Q2 and the second end of the resistor R7, the second end of the resistor R8 is connected to the first end of the capacitor C2 and the base of the NPN transistor Q1, and the second end of the capacitor C2 is connected to the anode of the diode D2;

[0014] The resistor R6 is connected between the second end of the resistor R4 and the anode of the diode D2, the second end of the resistor R2 is connected to the cathode of the diode D2 and the collector of the NPN transistor Q2; the emitter of the NPN transistor Q1 and the emitter of the NPN transistor Q2 are both connected to the negative electrode of the power supply DC;

[0015] The cathode of the diode D2 is connected to the AC conversion module as the output end of the astable multivibrator.

[0016] In one embodiment of the present invention, the AC conversion module includes an NPN transistor Q3, a PNP transistor Q4, a capacitor C3, a capacitor C4, a resistor R9 and a resistor R10, wherein:

[0017] The capacitor C3 and the capacitor C4 are connected in series between the positive electrode and the negative electrode of the power source DC, and the resistor R9 and the resistor R10 are connected in series between the positive electrode and the negative electrode of the power source DC; the node between the capacitor C3 and the capacitor C4 is connected to the node between the resistor R9 and the resistor R10;

[0018] The base of the NPN transistor Q3 and the base of the PNP transistor Q4 are both connected to the output end of the astable multivibrator, the collector of the NPN transistor Q3 is connected to the positive electrode of the power supply DC, the emitter of the NPN transistor Q3 is connected to the collector of the PNP transistor Q4 and the first end of the primary side of the transformer, and the emitter of the PNP transistor Q4 is connected to the negative electrode of the power supply DC;

[0019] A node between the resistor R9 and the resistor R10 is connected to the second end of the primary side of the transformer.

[0020] In one embodiment of the present invention, the capacitance values ​​of the capacitor C3 and the capacitor C4 are equal.

[0021] In one embodiment of the present invention, the resistance values ​​of the resistor R9 and the resistor R10 are equal.

[0022] In one embodiment of the present invention, the transformer includes a primary side and two secondary sides, and the number of the self-powered driving modules is two, wherein:

[0023] The input end of the first self-powered driving module is connected to the first secondary side of the transformer, and the output end is connected to the upper bridge M1 of the half-bridge structure;

[0024] The input end of the second self-powered driving module is connected to the second secondary side of the transformer, and the output end is connected to the lower bridge M2 of the half-bridge structure; M1 and M2 are alternately turned on half-bridge structures.

[0025] In one embodiment of the present invention, the self-powered driving module includes a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor Rg1, a resistor Rgs1, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a capacitor C5, a capacitor C6, a voltage regulator diode Dq1, a PNP transistor Q5, a PNP transistor Q7 and an NPN transistor Q6, wherein:

[0026] The first end of the resistor R11, the anode of the diode D3 and the anode of the diode D6 are all connected to the first end of the current secondary side of the transformer, and the second end of the resistor R11 is connected to the base of the PNP transistor Q5; the cathode of the diode D3 is connected to the first end of the resistor R12, the cathode of the diode D4, the first end of the resistor R13 and the cathode of the diode D5; the collector of the PNP transistor Q5, the anode of the diode D4, the emitter of the PNP transistor Q7, the anode of the voltage regulator diode Dq1 and the source of the NMOS tube M1 are all connected to the first end of the current secondary side of the transformer, and the emitter of the PNP transistor Q5 is connected to the second end of the resistor R12;

[0027] The second end of the resistor R13 is connected to the anode of the diode D5, the base of the NPN transistor Q6, the base of the PNP transistor Q7 and the first end of the capacitor C5, and the second end of the capacitor C5 is connected to the second end of the current secondary side of the transformer;

[0028] The resistor R14 and the capacitor C6 are connected in series between the cathode of the diode D6 and the collector of the NPN transistor Q6; the emitter of the NPN transistor Q6 is connected to the collector of the PNP transistor Q7, the first end of the resistor Rg1 and the cathode of the diode D7; the cathode of the voltage regulator diode Dq1 is connected to the collector of the NPN transistor Q6;

[0029] The anode of the diode D7 is connected to the second end of the resistor Rg1 and the first end of the resistor Rgs1. The anode of the diode D7 is connected to the gate of the upper bridge M1 of the half-bridge structure to be driven as the first output end of the self-power driving module. The second end of the resistor Rgs1 is connected to the source of the upper bridge M1.

[0030] In one embodiment of the present invention, the phases of the output signals of the two self-powered driving modules differ by 180°.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The self-powered half-bridge driving circuit of the present invention is composed of modules built with discrete components, including an astable multivibrator, an AC conversion module, a transformer and a self-powered driving module connected in sequence. The entire circuit contains only one independent power supply. All four modules can work in a high temperature environment. At the same time, the self-powered working mode reduces the use of power supply, which can better reduce heat production in a high temperature environment, ensure the stable operation of the circuit, and provide a driving solution for a high temperature and high pressure half-bridge circuit structure. The present invention can provide multi-channel isolation drive, and the driving signal has strong anti-interference ability.

[0033] 2. The self-powered driving module of the present invention can realize self-driving from the transformer, and at the same time, a delay link and a discharge path are reserved to provide dead time, so that the driving signal can maintain a good waveform while improving the reliability of the circuit to be driven.

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of module connection of a self-powered half-bridge driving circuit provided by an embodiment of the present invention;

[0036] Figure 2 1 is a schematic diagram of a circuit structure of an astable multivibrator provided by an embodiment of the present invention;

[0037] Figure 3 is a schematic diagram of a circuit structure of an AC conversion module provided by an embodiment of the present invention;

[0038] Figure 4 It is a circuit structure diagram of a self-powered driving module provided by an embodiment of the present invention;

[0039] Figure 5 It is a schematic diagram illustrating the principle of a self-powered driving module provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, a self-powered half-bridge driving circuit proposed in accordance with the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0041] The above and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific implementation modes in conjunction with the accompanying drawings. Through the description of the specific implementation modes, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes and are not used to limit the technical solutions of the present invention.

[0042] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the statement "including one..." do not exclude the existence of other identical elements in the article or device including the elements.

[0043] Embodiment 1

[0044] This embodiment provides a self-powered half-bridge driving circuit. The self-powered half-bridge driving circuit adopts analog circuit construction from signal generation to MOS tube driving. Figure 1 , Figure 1 This is a module connection diagram of a self-powered half-bridge driving circuit provided by an embodiment of the present invention. The self-powered half-bridge driving circuit comprises an astable multivibrator, an AC conversion module, a transformer and a self-powered driving module connected in sequence, wherein the astable multivibrator is used to generate a pulse square wave signal required for driving; the AC conversion module is used to convert the pulse square wave signal from the astable multivibrator into an AC square wave signal; the transformer is used to electrically isolate and amplify the AC square wave signal from the AC conversion module to obtain the amplified AC square wave signal; the self-powered driving module is used to rectify, delay and amplify the amplified AC square wave signal to drive the half-bridge circuit.

[0045] For further information, see Figure 2 , Figure 2 1 is a circuit structure diagram of an astable multivibrator provided by an embodiment of the present invention. The astable multivibrator includes a power supply DC, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D1, a diode D2, a capacitor C1, a capacitor C2, an NPN transistor Q1 and an NPN transistor Q2. The first end of the resistor R1, the first end of the resistor R3, the first end of the resistor R7, the first end of the resistor R8, the first end of the resistor R4 and the first end of the resistor R2 are all connected to the positive electrode of the power supply DC, the second end of the resistor R1 is connected to the cathode of the diode D1 and the collector of the NPN transistor Q1, and the resistor R5 is connected between the second end of the resistor R3 and the anode of the diode D1.

[0046] The first end of the capacitor C1 is connected to the anode of the diode D1, the second end of the capacitor C1 is connected to the base of the NPN transistor Q2 and the second end of the resistor R7, the second end of the resistor R8 is connected to the first end of the capacitor C2 and the base of the NPN transistor Q1, and the second end of the capacitor C2 is connected to the anode of the diode D2; the resistor R6 is connected between the second end of the resistor R4 and the anode of the diode D2, the second end of the resistor R2 is connected to the cathode of the diode D2 and the collector of the NPN transistor Q2; the emitter of the NPN transistor Q1 and the emitter of the NPN transistor Q2 are both connected to the negative electrode of the power supply DC; the cathode of the diode D2 is connected to the AC conversion module as the output end of the astable multivibrator.

[0047] It should be noted that for the driving circuit to work properly, it is usually necessary to provide a continuous square wave signal at the input end of the driving circuit. The device or equipment that can provide a square wave signal is usually called a signal source. This embodiment uses an astable multivibrator built with discrete components as a signal source. It relies on the dispersion of the device and the fact that the voltage of the capacitor cannot change suddenly to enable the triode to perform astable alternating work. Figure 2 As shown, assuming that NPN transistor Q1 is turned on first and quickly reaches the saturated conduction state, while NPN transistor Q2 is in the off state, the collector of NPN transistor Q1 is almost zero volts, and the left plate of capacitor C1 is also zero volts. At the same time, NPN transistor Q2 is in the off state, its collector is equal to the voltage of the power supply DC, and the initial potential of its base is approximately regarded as zero potential. At this time, capacitor C1 is still uncharged, and its two plates are at the same potential. After that, capacitor C1 begins to charge through resistor R7, and its right plate becomes more and more positive until it reaches a voltage of about +0.6V. Since this plate of capacitor C1 is also connected to the base of Q2, Q2 will begin to conduct and quickly enter the saturation zone.

[0048] The saturated conduction of NPN transistor Q2 causes its collector voltage to drop, causing the potential of the right plate of capacitor C2 to drop rapidly. While capacitor C1 is charging, capacitor C2 is charged through resistors R4 and R6, and the potential of the right plate of capacitor C2 after charging is higher than that of the left plate. When the potential of the right plate of capacitor C2 drops rapidly to zero, since the voltage of the capacitor cannot change suddenly, its left plate must drop by a similar amount, and the left plate of capacitor C2, i.e., the base potential of NPN transistor Q1, drops to about 0.6-Vcc volts, while the emitter potential of NPN transistor Q1 is zero, so NPN transistor Q1 is cut off, and its collector voltage rises rapidly to a positive potential Vcc close to the power supply DC.

[0049] However, this new state will not last. When the NPN transistor Q2 is turned on, the capacitor C2 begins to charge through the resistor R8. Similar to the previous process of Q2 changing from off to on and Q1 changing from on to off, once the voltage on the left plate (Q1 base) reaches about +0.6V, another rapid state change will occur, causing Q2 to be off and Q1 to be on. The entire circuit is accompanied by this process so that Q1 and Q2 are turned on alternately, and a complementary square wave with a duty cycle of 50% can be obtained at the collector end to the emitter end of each. The high level of the square wave is approximately the positive potential Vcc of the power supply DC, and the low level is zero.

[0050] It should be noted that the period of the astable multivibrator is realized by charging the resistor and capacitor. The capacitor C1 is charged via the resistor R7, and the capacitor C2 is charged via the resistor R8. The time for the capacitor to be fully charged to change state is about 0.7RC. The calculation formula for the period T of the astable multivibrator can be obtained as follows:

[0051] T=0.7(R 7 C 1 +R 8 C 2 )

[0052] Let R 7 =R 8 =R,C 1 =C 2 =C, we get:

[0053] T=RC

[0054] Therefore, the period T of the signal source is completely determined by the parameters of the resistor R7, the capacitor C1, the resistor R8 and the capacitor C2, which are usually pre-designed parameters.

[0055] The role of diode D1 and diode D2 is that each time the collector voltage of the transistor becomes high as the transistor is turned off, the diode becomes reverse biased, thereby isolating the pull-up of the transistor collector potential from the influence of the charging of capacitor C2, making the waveform of the rising edge steeper.

[0056] The role of connecting resistors R3 and R5 in series and resistors R4 and R6 in series is to artificially increase the dispersion of the circuit to avoid the circuit not working due to the excessive consistency of the devices. Resistors R3, R5, R4, and R6 can be set to the same parameters. Once the circuit does not work due to insufficient dispersion, the value of one or two of them can be appropriately changed to improve the dispersion.

[0057] For further information, see Figure 3 , Figure 31 is a schematic diagram of a circuit structure of an AC conversion module provided by an embodiment of the present invention. The AC conversion module includes an NPN transistor Q3, a PNP transistor Q4, a capacitor C3, a capacitor C4, a resistor R9 and a resistor R10, wherein the capacitor C3 and the capacitor C4 are connected in series between the positive and negative electrodes of the power supply DC, and the resistors R9 and R10 are connected in series between the positive and negative electrodes of the power supply DC; the node between the capacitor C3 and the capacitor C4 is connected to the node between the resistor R9 and the resistor R10; the base of the NPN transistor Q3 and the base of the PNP transistor Q4 are both connected to the output end of the astable multivibrator, the collector of the NPN transistor Q3 is connected to the positive electrode of the power supply DC, the emitter of the NPN transistor Q3 is connected to the collector of the PNP transistor Q4 and the first end of the primary side of the transformer, and the emitter of the PNP transistor Q4 is connected to the negative electrode of the power supply DC; the node between the resistor R9 and the resistor R10 is connected to the second end of the primary side of the transformer.

[0058] In the AC conversion module of this embodiment, the NPN transistor Q3 and the PNP transistor Q4 form a push-pull amplifier circuit, and the capacitor C3, the capacitor C4, the resistor R9 and the resistor R10 form a resistor-capacitor voltage divider network. The capacitance values ​​of the capacitor C3 and the capacitor C4 are equal. The resistance values ​​of the resistor R9 and the resistor R10 are equal.

[0059] Specifically, due to the high temperature and the driving requirements of the main circuit topology, this embodiment needs to use magnetic isolation to transmit and isolate the driving signal, and the signal generated by the astable multivibrator is a pulse square wave signal, which cannot be directly transmitted through the transformer, and the pulse square wave signal needs to be converted into an AC square wave signal first. The power supply of the AC conversion module of this embodiment shares a power supply DC with the astable multivibrator, and the output end of the astable multivibrator is connected to the input end of the AC conversion module. The AC conversion module consists of two parts: one part is a push-pull drive circuit, which is used to amplify the output current of the astable multivibrator to facilitate the transmission of the waveform through the transformer; the other part is a resistor-capacitor voltage divider network.

[0060] The working principle of the AC conversion module is as follows: since C3 = C4, R9 = R10, the potential in the middle of the H bridge of the resistor-capacitor voltage divider network is the second end of the primary side of the transformer ( Figure 3 The potential at the two ends of When the rising edge of the pulse square wave signal (signal source) from the astable multivibrator comes, the NPN transistor Q3 is turned on, the PNP transistor Q4 is turned off, and the voltage across the primary side of the transformer is: When the falling edge of the signal source comes, the PNP transistor Q4 is turned on, the NPN transistor Q3 is turned off, and the voltage across the primary side of the transformer is: So the waveform at both ends of the transformer becomes a period that is consistent with the signal source period, and the amplitude is The square wave is amplified by the push-pull amplifier structure, and the primary side of the transformer has enough current to ensure that the waveform is not distorted.

[0061] The transformer of this embodiment includes a primary side and two secondary sides, and the number of self-power driving modules is two, wherein the input end of the first self-power driving module is connected to the first secondary side of the transformer, and the output end is connected to the upper bridge M1 of the half-bridge structure; the input end of the second self-power driving module is connected to the second secondary side of the transformer, and the output end is connected to the lower bridge M2 of the half-bridge structure; M1 and M2 are half-bridge structures that are alternately turned on.

[0062] As mentioned above, due to the limitation of high temperature environment, the signal source can only be realized by the astable multivibrator. Similarly, the high temperature environment makes it difficult for the silicon-based isolation driver chip to break through the 125°C limit to provide the driving signal for the main circuit. Therefore, when considering the design of the driving circuit, this embodiment still needs to use a driving circuit built with discrete components.

[0063] In this embodiment, more attention is paid to the switching and driving conditions of MOSFET during the drive design, so the circuit can be simplified, that is, M1 and M2 are half-bridge structures that are alternately turned on, and the drain of M2 is connected to the output resistor Ro. Therefore, according to this model, specific requirements are put forward for the drive circuit built by discrete components: (1) All discrete components used in the drive circuit can meet the high temperature requirements, (2) Both drive paths are isolated drives, (3) The phase difference of the two drive signals providing drive for the main circuit should be 180°, (4) A certain dead time should be reserved for the two drive signals to ensure the normal operation of the circuit, (5) Two-way isolated drive requires two independent isolated power supplies to provide energy for push-pull drive, and (6) The hard shutdown of the circuit requires a certain overvoltage protection.

[0064] The self-powered driving module of this embodiment has the functions of rectification, delay, and signal amplification. The power required by the push-pull structure (push-pull amplifier circuit) for amplifying the signal is obtained by self-powering the transformer, which can further optimize the signal to meet the signal requirements of the driving circuit. Figure 4 , Figure 4 1 is a schematic diagram of the circuit structure of a self-powered driving module provided by an embodiment of the present invention. The self-powered driving module includes a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor Rg1, a resistor Rgs1, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a capacitor C5, a capacitor C6, a voltage regulator diode Dq1, a PNP transistor Q5, a PNP transistor Q7 and an NPN transistor Q6.

[0065] The first end of the resistor R11, the anode of the diode D3 and the anode of the diode D6 are all connected to the first end of the current secondary side of the transformer, and the second end of the resistor R11 is connected to the base of the PNP transistor Q5; the cathode of the diode D3 is connected to the first end of the resistor R12, the cathode of the diode D4, the first end of the resistor R13 and the cathode of the diode D5; the collector of the PNP transistor Q5, the anode of the diode D4, the emitter of the PNP transistor Q7, the anode of the voltage regulator diode Dq1 and the source of the NMOS tube M1 are all connected to the first end of the current secondary side of the transformer, and the emitter of the PNP transistor Q5 is connected to the second end of the resistor R12.

[0066] The second end of the resistor R13 is connected to the anode of the diode D5, the base of the NPN transistor Q6, the base of the PNP transistor Q7 and the first end of the capacitor C5, and the second end of the capacitor C5 is connected to the second end of the current secondary side of the transformer; the resistor R14 and the capacitor C6 are connected in series between the cathode of the diode D6 and the collector of the NPN transistor Q6, and the emitter of the NPN transistor Q6 is connected to the collector of the PNP transistor Q7, the first end of the resistor Rg1 and the cathode of the diode D7; the cathode of the Zener diode Dq1 is connected to the collector of the NPN transistor Q6.

[0067] The anode of the diode D7 is connected to the second end of the resistor Rg1 and the first end of the resistor Rgs1. The anode of the diode D7 is connected to the gate of the upper bridge M1 of the half-bridge structure to be driven as the first output end of the self-powered driving module. The second end of the resistor Rgs1 is connected to the source of the upper bridge M1 to protect the stable switching of the device to be driven.

[0068] Correspondingly, the input end of the second self-powered driving module of this embodiment is connected to the second secondary side of the transformer, corresponding to Figure 4 5 and 6 in the circuit, and at the same time, the first output end of the second self-powered driving module is connected to the gate of the lower bridge M2 of the half-bridge structure to be driven, and the second output end is connected to the source of the lower bridge M2.

[0069] like Figure 4 As shown, the two self-powered driving modules are respectively connected to the two secondary sides of the transformer, and the pins of the same-named ends of the two secondary sides are opposite. The self-powered driving module driving M1 is the upper bridge driver, and the self-powered driving module driving M2 is the lower bridge driver. The circuit structures of the two self-powered driving modules are exactly the same, and the only difference is that the same-named ends connected to the transformer are just opposite. The purpose is to reduce the use of transformers while making the output signals of the two self-powered driving modules complementary, that is, the two signals are 180° out of phase.

[0070] Since the driving circuits of the upper and lower bridges M1 and M2 are exactly the same, only one of the bridges is used to explain its working principle. For example, see Figure 5 , Figure 5 It is a schematic diagram illustrating the principle of a self-powered driving module provided by an embodiment of the present invention. Figure 5 Points 3 and 4 in the figure are the two ends of the first secondary side of the transformer. To facilitate the explanation and distinction of the grounds of different signals, the potential of point 4 is recorded as AGND. When describing the potential and voltage waveform of point 3 and points A, B, C, D, and G, they are all relative to the potential or voltage waveform of AGND. After the voltage waveform is transmitted to the secondary side through the transformer, the signal is divided into two paths. One signal passes through diode D6, resistor R14, capacitor C6, and voltage regulator diode Dq1 and returns to the secondary side to provide the power supply voltage required for driving the push-pull amplifier circuit. Among them, the role of diode D6 is half-wave rectification, removing the waveform of the AC part, but the voltage waveform passing through diode D6 only has the positive half-cycle part of the original waveform half cycle, so capacitor C6 needs to be a capacitor with a larger capacity to store the energy after passing through diode D6 while maintaining the power supply voltage required for driving. In this way, through the cooperation of diode D6 and capacitor C6, a more reliable DC power supply required for driving the push-pull amplifier circuit can be obtained. At the same time, in order to prevent the voltage fluctuation from the signal source from affecting the push-pull amplifier circuit and the drive of the SiC MOSFET half-bridge structure and to provide a suitable driving voltage for the SiC MOSFET, a voltage regulator diode is connected in parallel at the energy storage capacitor C6. Furthermore, since the voltage regulator diode may work in a breakdown state, it is also necessary to connect a resistor R14 in series behind the diode D6. The purpose is to limit the current flowing through the voltage regulator tube to prevent the voltage regulator tube from overpowering and burning. Another signal is transmitted to the push-pull structure composed of NPN transistor Q6 and PNP transistor Q7 through diode D3 to provide a driving signal for it. The role of the same diode D3 here is the same as that of diode D6. Its main function is to perform half-wave rectification and retain the positive half-cycle of the AC square wave.

[0071] However, the signal directly rectified and then push-pull amplified cannot well guarantee the dead time of the two complementary signals, so it is necessary to add a circuit that can provide dead time on this basis. Due to the need for dead time, the two MOS tubes cannot be turned on at the same time, that is, the two signals cannot be at a high level at the same time. Converted into circuit language, it means that after one of the signals completes the falling edge action, the other signal can perform the rising edge action. The solution adopted in this embodiment is that the diode D5, the resistor R13, and the capacitor C5 form an RC delay circuit. The resistor R13 and the capacitor C5 form an RC delay, and the diode D5 provides a fast shutdown solution to insert the dead time. Its working principle is as follows: Figure 5 As shown, when the rising edge of point A comes, diode D5 is cut off, and the signal returns to AGND through resistor R13 and capacitor C5. At this time, the signal at point B will lag behind point A by time τ, where τ is the time constant of RC charging; when the falling edge of point A comes, diode D5 is turned on, and the RC time delay of the signal path is zero, and point B has no lag relative to point A.

[0072] However, there is a problem with using this delay structure directly. The existence of capacitor C5 is not only a part of the RC delay, but also has the ability to store charge like capacitor C6. However, there is no channel or energy-consuming element in the circuit to release this part of the stored charge for capacitor C5. If a resistor is directly connected in parallel at capacitor C5, the delay effect will be lost. When the value of C6 is large, the waveform at point B will be consistent with the waveform at point D; when the value of capacitor C6 is small, the falling edge of point B will also lag behind point A, and the desired waveform cannot be obtained. Therefore, this embodiment provides an additional discharge circuit for this delay capacitor that is only effective on the falling edge, that is, a PNP transistor Q5 is added for discharge. Similarly, when the transition of point 3 is a positive half-cycle, diode D3 is turned on, the voltage between the base and the emitter of PNP transistor Q5 is Vbe=0V, the emitter junction is reverse biased, the transistor is turned off, and the signal is delayed along the RC loop; when the transition of point 3 is a negative half-cycle, diode D3 is turned off, Vbe<-0.7V, the voltage between the base and the collector of PNP transistor Q5 is Vbc<0V, the emitter junction is forward biased, the collector junction is forward biased, the transistor is saturated and turned on, and the charge that cannot be released stored in the original capacitor C5 is released through diode D5 and transistor Q5. Only at this time can a square wave signal with a rising edge lagging behind point A by time τ and a falling edge consistent with point A be obtained at point B. Diode D4 can be a general diode or a voltage regulator diode. If it is a voltage regulator diode, its voltage regulation value should be consistent with that of voltage regulator diode Dq1, which can limit and stabilize the amplitude of the high level of the square wave signal, but both the voltage regulator diode and the general diode play the role of a freewheeling protection circuit. Since both the upper bridge and the lower bridge adopt this structure, and the signal phases of the upper and lower bridges differ by 180°, a dead time of approximately τ can be obtained every half cycle.

[0073] After obtaining the complementary driving signal with a certain dead time, in order to further provide driving capability, a necessary approach is to use a push-pull structure to amplify the signal. The push-pull structure can not only increase the driving current but also modify the waveform to make the edge of the waveform steeper and the high-level platform more stable. The driving resistor Rg1 after the push-pull structure is used to limit the current, control the switch response speed, and prevent the driving voltage oscillation caused by parasitic inductance and burn out the MOS tube. A diode D7 connected in parallel with it can accelerate the shutdown.

[0074] The self-powered half-bridge drive circuit of the present invention is composed of modules built with discrete components, including an astable multivibrator, an AC conversion module, a transformer, and a self-powered drive module connected in sequence. The entire circuit contains only one independent power supply, and all four modules can operate in a high-temperature environment. At the same time, the self-powered operating mode reduces the power consumption, can better reduce the heat generation in a high-temperature environment, ensure the stable operation of the circuit, and provide a drive solution for the high-temperature and high-pressure half-bridge circuit structure. The present invention can provide multiple isolated drives, and the drive signal has strong anti-interference ability. The self-powered drive module of the present invention can realize self-driving from the transformer, and at the same time has a delay link and a discharge path to provide dead time, so that the drive signal can improve the reliability of the circuit to be driven while maintaining a good waveform.

[0075] In several embodiments provided by the present invention, it should be understood that the devices and methods disclosed by the present invention can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the modules is only a logical function division. In actual implementation, there may be other division methods. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0076] In addition, each functional module in various embodiments of the present invention can be integrated in a processing module, or each module can exist physically alone, or two or more modules can be integrated in one module. The above integrated modules can be implemented in the form of hardware, or in the form of hardware plus software functional modules.

[0077] The above content is a further detailed description of the present invention in combination with specific preferred implementation manners. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A self-powered half-bridge driving circuit, characterized in that: It includes an astable multivibrator, an AC conversion module, a transformer and a self-powered driving module connected in sequence, wherein: The astable multivibrator is used to generate a pulse square wave signal required for driving; The AC conversion module is used to convert the pulse square wave signal from the astable multivibrator into an AC square wave signal; The transformer is used to electrically isolate and amplify the AC square wave signal from the AC conversion module to obtain an amplified AC square wave signal; The self-powered driving module is used to rectify, delay and amplify the amplified AC square wave signal to drive the half-bridge circuit.

2. The self-powered half-bridge driving circuit according to claim 1, characterized in that: The astable multivibrator includes a power supply DC, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a diode D1, a diode D2, a capacitor C1, a capacitor C2, an NPN transistor Q1 and an NPN transistor Q2, wherein: The first end of the resistor R1, the first end of the resistor R3, the first end of the resistor R7, the first end of the resistor R8, the first end of the resistor R4 and the first end of the resistor R2 are all connected to the positive electrode of the power supply DC, the second end of the resistor R1 is connected to the cathode of the diode D1 and the collector of the NPN transistor Q1, and the resistor R5 is connected between the second end of the resistor R3 and the anode of the diode D1; The first end of the capacitor C1 is connected to the anode of the diode D1, the second end of the capacitor C1 is connected to the base of the NPN transistor Q2 and the second end of the resistor R7, the second end of the resistor R8 is connected to the first end of the capacitor C2 and the base of the NPN transistor Q1, and the second end of the capacitor C2 is connected to the anode of the diode D2; The resistor R6 is connected between the second end of the resistor R4 and the anode of the diode D2, the second end of the resistor R2 is connected to the cathode of the diode D2 and the collector of the NPN transistor Q2; the emitter of the NPN transistor Q1 and the emitter of the NPN transistor Q2 are both connected to the negative electrode of the power supply DC; The cathode of the diode D2 is connected to the AC conversion module as the output end of the astable multivibrator.

3. The self-powered half-bridge driving circuit according to claim 2, characterized in that: The AC conversion module includes an NPN transistor Q3, a PNP transistor Q4, a capacitor C3, a capacitor C4, a resistor R9 and a resistor R10, wherein: The capacitor C3 and the capacitor C4 are connected in series between the positive electrode and the negative electrode of the power source DC, and the resistor R9 and the resistor R10 are connected in series between the positive electrode and the negative electrode of the power source DC; the node between the capacitor C3 and the capacitor C4 is connected to the node between the resistor R9 and the resistor R10; The base of the NPN transistor Q3 and the base of the PNP transistor Q4 are both connected to the output end of the astable multivibrator, the collector of the NPN transistor Q3 is connected to the positive electrode of the power supply DC, the emitter of the NPN transistor Q3 is connected to the collector of the PNP transistor Q4 and the first end of the primary side of the transformer, and the emitter of the PNP transistor Q4 is connected to the negative electrode of the power supply DC; A node between the resistor R9 and the resistor R10 is connected to the second end of the primary side of the transformer.

4. The self-powered half-bridge driving circuit according to claim 3, characterized in that: The capacitance values ​​of the capacitor C3 and the capacitor C4 are equal.

5. The self-powered half-bridge driving circuit according to claim 3, characterized in that: The resistance value of the resistor R9 is equal to that of the resistor R10.

6. The self-powered half-bridge driving circuit according to claim 2, characterized in that: The transformer includes a primary side and two secondary sides, and the number of the self-powered driving modules is two, wherein: The input end of the first self-powered driving module is connected to the first secondary side of the transformer, and the output end is connected to the upper bridge M1 of the half-bridge structure; The input end of the second self-powered driving module is connected to the second secondary side of the transformer, and the output end is connected to the lower bridge M2 of the half-bridge structure; M1 and M2 are alternately turned on half-bridge structures.

7. The self-powered half-bridge driving circuit according to claim 6, characterized in that: The self-powered driving module includes a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor Rg1, a resistor Rgs1, a diode D3, a diode D4, a diode D5, a diode D6, a diode D7, a capacitor C5, a capacitor C6, a voltage regulator diode Dq1, a PNP transistor Q5, a PNP transistor Q7 and an NPN transistor Q6, wherein: The first end of the resistor R11, the anode of the diode D3 and the anode of the diode D6 are all connected to the first end of the current secondary side of the transformer, and the second end of the resistor R11 is connected to the base of the PNP transistor Q5; the cathode of the diode D3 is connected to the first end of the resistor R12, the cathode of the diode D4, the first end of the resistor R13 and the cathode of the diode D5; the collector of the PNP transistor Q5, the anode of the diode D4, the emitter of the PNP transistor Q7, the anode of the voltage regulator diode Dq1 and the source of the NMOS tube M1 are all connected to the first end of the current secondary side of the transformer, and the emitter of the PNP transistor Q5 is connected to the second end of the resistor R12; The second end of the resistor R13 is connected to the anode of the diode D5, the base of the NPN transistor Q6, the base of the PNP transistor Q7 and the first end of the capacitor C5, and the second end of the capacitor C5 is connected to the second end of the current secondary side of the transformer; The resistor R14 and the capacitor C6 are connected in series between the cathode of the diode D6 and the collector of the NPN transistor Q6; the emitter of the NPN transistor Q6 is connected to the collector of the PNP transistor Q7, the first end of the resistor Rg1 and the cathode of the diode D7; the cathode of the voltage regulator diode Dq1 is connected to the collector of the NPN transistor Q6; The anode of the diode D7 is connected to the second end of the resistor Rg1 and the first end of the resistor Rgs1. The anode of the diode D7 is connected to the gate of the upper bridge M1 of the half-bridge structure to be driven as the first output end of the self-power driving module. The second end of the resistor Rgs1 is connected to the source of the upper bridge M1.

8. The self-powered half-bridge driving circuit according to claim 6, characterized in that: The phase difference between the output signals of the two self-powered driving modules is 180°.

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