Detection circuit for abnormal conduction of switching tube

Abstract

The utility model provides a switch tube abnormal conduction detection circuit comprising a bridge type switch circuit, a DC bus circuit and an AC bus circuit which are connected with the bridge type switch circuit, and a voltage sampling circuit and a current sampling circuit which are respectively connected with the DC bus circuit and the AC bus circuit. The detection module is respectively connected with the voltage sampling circuit and the current sampling circuit, the main control module is connected with the detection module, the direct-current bus circuit and the alternating-current bus circuit are sampled through the voltage sampling circuit and the current sampling circuit, then sampling signals are detected through the detection module, and a detection result is sent to the main control module. The main control module controls the bridge type switching circuit to stop receiving the direct current voltage of the direct current bus circuit when the switching tube is abnormally conducted according to the judgment result, so that driving waveform abnormal conduction detection is performed on the switching tube, and a protection mechanism is triggered under the abnormal conduction condition; and the operation stability and reliability of the switching power supply are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a detection circuit for abnormal conduction of a switch tube. Background Art

[0002] MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a semiconductor device widely used in electronic circuits, especially in digital circuits and power management. With its high performance, low power consumption and high-speed switching characteristics, it has become a core component in modern integrated circuit design.

[0003] When using a power MOSFET bridge topology, the gate drive signal may oscillate during the switching process between the two power devices in the same bridge arm, significantly increasing power device losses. High oscillation amplitudes can even cause the power devices to unexpectedly turn on, leading to shoot-through in the power switches and ultimately damaging the devices. However, conventional MOSFET protection strategies are unable to diagnose transient shoot-through failures in the upper and lower MOSFETs. Utility Model Content

[0004] In view of the above problems, the present invention is proposed to provide a detection circuit for abnormal conduction of a switch tube that overcomes the above problems or at least partially solves the above problems.

[0005] In order to solve the above problems, the utility model discloses a detection circuit for abnormal conduction of a switch tube, comprising:

[0006] A bridge switching circuit, a DC bus circuit and an AC bus circuit connected to the bridge switching circuit, a voltage sampling circuit and a current sampling circuit connected to the DC bus circuit and the AC bus circuit respectively, a detection module connected to the voltage sampling circuit and the current sampling circuit respectively, and a main control module connected to the detection module;

[0007] The bridge switch circuit is used to convert the DC voltage of the DC bus circuit into an AC voltage and transmit the AC voltage to the AC bus circuit;

[0008] The voltage sampling circuit is used to sample the voltages of the DC bus circuit and the AC bus circuit, and transmit the voltage sampling signals to the detection module;

[0009] The current sampling circuit is used to sample the current of the DC bus circuit and the AC bus circuit, and transmit the current sampling signal to the detection module;

[0010] The detection module is configured to determine whether the switch tube of the bridge switch circuit is abnormally turned on based on the voltage sampling signal and the current sampling signal, and send the determination result to the main control module;

[0011] The main control module is used to determine whether the switch tube of the bridge switch circuit is abnormally turned on based on the judgment result, and when the switch tube of the bridge switch circuit is abnormally turned on, control the bridge switch circuit to stop receiving the DC voltage of the DC bus circuit.

[0012] Optionally, the DC bus circuit includes multiple capacitors and a DC bus; the DC bus includes a positive pole and a negative pole; the multiple capacitors are connected in parallel between the positive pole and the negative pole of the DC bus, for transmitting the DC voltage of the DC bus to the bridge switching circuit.

[0013] Optionally, the DC bus circuit also includes a contactor; one end of the contactor is connected to the positive pole of the DC bus, and the other end is connected to the bridge switching circuit, for controlling whether the DC voltage of the positive pole of the DC bus is transmitted to the bridge switching circuit.

[0014] Optionally, the bridge switching circuit includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube; the first switching tube and the third switching tube are upper bridge switching tubes, the second switching tube and the fourth switching tube are lower bridge switching tubes, the first switching tube and the third switching tube are used to receive the DC voltage of the positive pole of the DC bus; the second switching tube and the fourth switching tube are used to receive the DC voltage of the negative pole of the DC bus.

[0015] Optionally, the input end of the first switching tube is connected to the positive pole of the DC bus, and the output end is connected to the second switching tube; the input end of the second switching tube is connected to the negative pole of the DC bus, and the output end is connected to the fourth switching tube; the input end of the third switching tube is connected between the positive pole of the DC bus and the first switching tube, and the output end is connected to the fourth switching tube; the input end of the fourth switching tube is connected between the negative pole of the DC bus and the second switching tube, and the output end is connected to the third switching tube.

[0016] Optionally, the bridge switching circuit includes a first output end and a second output end; the first output end is arranged between the first switching tube and the second switching tube, and is used to output the AC voltage; the second output end is arranged between the third switching tube and the fourth switching tube, and is used to output the AC voltage.

[0017] Optionally, the AC bus circuit comprises an AC bus, a first inductor and a second inductor; the AC bus comprises a live wire and a zero line; one end of the first inductor is connected with the first output end, and the other end is connected with the live wire of the AC bus; one end of the second inductor is connected with the second output end, and the other end is connected with the zero line of the AC bus.

[0018] Optionally, the voltage sampling circuit comprises at least one voltage sampling resistor, a first bypass capacitor and a first filter capacitor connected with the voltage sampling resistor, a first operational amplifier having one end connected with the voltage sampling resistor and the other end outputting the voltage sampling signal.

[0019] Optionally, the current sampling circuit comprises at least one current sampling resistor, a second bypass capacitor and a second filter capacitor connected with the current sampling resistor, a second operational amplifier having one end connected with the current sampling resistor and the other end outputting the current sampling signal.

[0020] Optionally, the detection module comprises a short-circuit detection module and an oscillation detection module; the short-circuit detection module is used for receiving the current sampling signal, judging whether the bridge-type switching circuit is short-circuited according to the current sampling signal, and sending the judgment result to the main control module; the oscillation detection module is used for receiving the current sampling signal and the voltage sampling signal, judging whether the switching tube of the bridge-type switching circuit is abnormally turned on according to the current sampling signal and the voltage sampling signal, and sending the judgment result to the main control module.

[0021] Optionally, the main control module is used for stopping sending the pulse signal to the bridge-type switching circuit when the switching tube of the bridge-type switching circuit is abnormally turned on.

[0022] The utility model discloses the following advantages:

[0023] The present invention provides a detection circuit for abnormal conduction of a switching tube, comprising a bridge switching circuit, a DC bus circuit and an AC bus circuit connected to the bridge switching circuit, a voltage sampling circuit and a current sampling circuit respectively connected to the DC bus circuit and the AC bus circuit, a detection module respectively connected to the voltage sampling circuit and the current sampling circuit, and a main control module connected to the detection module, wherein the bridge switching circuit is configured to convert a DC voltage of the DC bus circuit into an AC voltage and transmit the AC voltage to the AC bus circuit; the voltage sampling circuit is configured to sample the voltages of the DC bus circuit and the AC bus circuit and transmit the voltage sampling signals to the detection module; the current sampling circuit is configured to sample the currents of the DC bus circuit and the AC bus circuit and transmit the current sampling signals to the detection module; the detection module is configured to determine whether the switching tube of the bridge switching circuit is abnormally conducted based on the voltage sampling signals and the current sampling signals, and transmit the determination result to the main control module; the main control module is configured to determine whether the switching tube of the bridge switching circuit is abnormally conducted based on the determination result, and control the bridge switching circuit to stop receiving the DC voltage of the DC bus circuit when the switching tube of the bridge switching circuit is abnormally conducted. The voltage sampling circuit and the current sampling circuit are used to sample the voltage and current of the DC bus circuit and the AC bus circuit connected to the bridge switching circuit. Then, the voltage sampling signal and the current sampling signal are detected by the detection module and the detection result is sent to the main control module. The main control module determines whether the switch tube of the bridge switching circuit is abnormally turned on based on the judgment result. When the switch tube of the bridge switching circuit is abnormally turned on, the main control module controls the bridge switching circuit to stop receiving the DC voltage of the DC bus circuit, thereby realizing the abnormal conduction detection of the driving waveform of the switch tube. If abnormal conduction occurs, the protection mechanism is triggered, thereby improving the operating stability and reliability of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural diagram of a detection circuit for abnormal conduction of a switch tube according to the present invention;

[0025] Figure 2 This is a structural diagram of another detection circuit for abnormal conduction of a switch tube according to the present invention;

[0026] Figure 3 This is a structural diagram of a voltage sampling circuit of the utility model;

[0027] Figure 4 This is a structural diagram of a current sampling circuit of the utility model.

[0028] Bridge switch circuit 10, first switch tube 11, second switch tube 12, third switch tube 13, fourth switch tube 14, first output end 15, second output end 16, DC bus circuit 20, capacitor 21, DC bus 22, contactor 23, AC bus circuit 30, AC bus 31, first inductor 32, second inductor 33, voltage sampling circuit 40, voltage sampling resistor 41, voltage sampling point 411, first bypass capacitor 42, first filter capacitor 43, first operational amplifier 44, current sampling circuit 50, current sampling resistor 51, current sampling point 511, second bypass capacitor 52, second filter capacitor 53, second operational amplifier 54, detection module 60, main control module 70. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the utility model will be further explained in detail below with the help of the drawings and specific embodiments.

[0030] When the power MOSFET bridge topology structure is adopted, the grid drive signal of the two power devices on the same bridge arm may oscillate in the conversion process, which leads to a significant increase in the loss of the power device, and when the oscillation amplitude is high, the power device may even be accidentally turned on, which further leads to the shoot-through phenomenon of the power switch tube, and finally leads to the damage of the device. However, the conventional MOSFET protection strategy cannot diagnose the upper and lower MOSFET transient shoot-through failure problem.

[0031] One of the core ideas of the utility model is that the voltage sampling circuit and the current sampling circuit are used to sample the voltage and current of the DC bus circuit and the AC bus circuit connected with the bridge switch circuit, then the detection module is used to detect the voltage sampling signal and the current sampling signal and send the detection results to the main control module, the main control module determines whether the switch tube of the bridge switch circuit is abnormally turned on according to the judgment result, and when the switch tube of the bridge switch circuit is abnormally turned on, the bridge switch circuit is controlled to stop receiving the DC voltage of the DC bus circuit, so that the abnormal conduction detection of the driving waveform of the switch tube is realized, and if the abnormal conduction occurs, the protection mechanism is triggered, and the operation stability and reliability of the switching power supply are improved.

[0032] REFERENCE Figure 1 , a structure schematic view of the utility model's switch tube abnormal conduction detection circuit is shown, which can specifically include the following structures:

[0033] A bridge switching circuit 10, a DC bus circuit 20 and an AC bus circuit 30 connected to the bridge switching circuit 10, a voltage sampling circuit 40 and a current sampling circuit 50 respectively connected to the DC bus circuit 20 and the AC bus circuit 30, a detection module 60 respectively connected to the voltage sampling circuit 40 and the current sampling circuit 50, and a main control module 70 connected to the detection module 60.

[0034] The bridge switching circuit 10 is used to convert the DC voltage of the DC bus circuit 20 into an AC voltage, and transmit the AC voltage to the AC bus circuit 30 .

[0035] The main feature of the bridge switching circuit is that it can effectively control the direction and magnitude of the current, thereby achieving voltage conversion and regulation. The bridge switching circuit is usually composed of four switching devices (such as MOSFET, IGBT, etc.), which are switched on and off in a specific order to control the flow path of the current. Bridge circuits can be divided into two main types: full-bridge circuit, which consists of four switching devices and can achieve positive and negative voltage conversion; half-bridge circuit, which consists of two switching devices and is usually used for lower power

[0036] Application of rate.

[0037] A DC bus circuit 20 and an AC bus circuit 30 are connected to the bridge switching circuit 10 .

[0038] The circuit of the present invention can be a bidirectional inverter power supply circuit. The bidirectional inverter power supply can realize the bidirectional flow of electric energy, that is, it can convert direct current into alternating current (inversion) and can also convert alternating current into direct current (rectification). The bidirectional inverter power supply is usually composed of the following main parts: switching devices, such as MOSFET, IGBT, etc., used to control the direction and size of the flow of electric energy; filters, used to smooth the output voltage and current, reduce harmonics and noise; control circuits, used to adjust the on and off time of the switching devices to achieve precise control of voltage and current; the DC side and the AC side, respectively connected to the DC power supply (such as batteries, supercapacitors, etc.) and the AC load (such as the power grid, motors, etc.). The working principle of the bidirectional inverter power supply is based on switching power supply technology, and the bidirectional flow of electric energy is achieved by controlling the on and off time of the switching devices. The following are the basic working modes of bidirectional inverter power supplies: Inversion mode (DC to AC), converting DC power into AC power. Working principle: the control circuit controls the on and off of the switching device according to a specific frequency and phase, and converts the DC voltage into AC voltage by periodically switching on and off. The frequency and phase of the output AC voltage can be adjusted by the control circuit; Rectification mode (AC toDC): converting AC power into DC power. Working principle: the control circuit detects the phase and frequency of the input AC voltage, and controls the on and off of the switching device according to the detection results, converting the AC voltage into DC voltage, and smoothing the output DC voltage through the filter to reduce ripple and noise.

[0039] The DC bus circuit 20 is the DC side of the bidirectional inverter power supply, and the AC bus circuit 30 is the AC side of the bidirectional inverter power supply.

[0040] The voltage sampling circuit 40 is used to sample the voltage of the DC bus circuit 20 and the AC bus circuit 30, and transmit the voltage sampling signal to the detection module 60. The current sampling circuit 50 is used to sample the current of the DC bus circuit 20 and the AC bus circuit 30, and transmit the current sampling signal to the detection module 60.

[0041] The detection module 60 is used to determine whether the switch tube of the bridge switch circuit 10 is abnormally turned on based on the voltage sampling signal and the current sampling signal, and send the determination result to the main control module 70.

[0042] The main control module 70 is used to determine whether the switch tube of the bridge switch circuit 10 is abnormally turned on based on the judgment result, and when the switch tube of the bridge switch circuit 10 is abnormally turned on, control the bridge switch circuit 10 to stop receiving the DC voltage from the DC bus circuit 20.

[0043] The detection circuit of abnormal conduction of the switch tube of the present invention includes a bridge switch circuit 10, a DC bus circuit 20 and an AC bus circuit 30 connected to the bridge switch circuit 10, a voltage sampling circuit 40 and a current sampling circuit 50 connected to the DC bus circuit 20 and the AC bus circuit 30 respectively, a detection module 60 connected to the voltage sampling circuit 40 and the current sampling circuit 50 respectively, and a main control module 70 connected to the detection module 60, wherein the bridge switch circuit 10 is used to convert the DC voltage of the DC bus circuit 20 into an AC voltage and transmit the AC voltage to the AC bus circuit 30; the voltage sampling circuit 40 is used to detect the DC bus circuit 20 and the AC bus circuit 30. The main control module 70 is used to determine whether the switch tube of the bridge switching circuit 10 is abnormally turned on based on the judgment result, and when the switch tube of the bridge switching circuit 10 is abnormally turned on, control the bridge switching circuit 10 to stop receiving the DC voltage of the DC bus circuit. The voltage sampling circuit 40 and the current sampling circuit 50 perform voltage sampling and current sampling on the DC bus circuit 20 and the AC bus circuit 30 connected to the bridge switching circuit 10. Then, the detection module 60 detects the voltage sampling signal and the current sampling signal and sends the detection result to the main control module 70. The main control module 70 determines whether the switch tube of the bridge switching circuit 10 is abnormally conductive based on the judgment result. When the switch tube of the bridge switching circuit 10 is abnormally conductive, the main control module 70 controls the bridge switching circuit 10 to stop receiving the DC voltage of the DC bus circuit, thereby realizing abnormal conductive detection of the driving waveform of the switch tube. If abnormal conductive condition occurs, the protection mechanism is triggered, thereby improving the operating stability and reliability of the switching power supply.

[0044] Reference Figure 2 , shows a structural schematic diagram of another detection circuit for abnormal conduction of a switch tube of the present invention.

[0045] The DC bus circuit 20 includes multiple capacitors 21 and a DC bus 22; the DC bus 22 includes a positive pole and a negative pole; multiple capacitors 21 are connected in parallel between the positive pole and the negative pole of the DC bus 22, and are used to transmit the DC voltage of the DC bus 22 to the bridge switching circuit 10.

[0046] The DC bus generally refers to the common connection point or bus used to transmit DC power within a system. It connects power supplies, loads, converters, and other power electronics, ensuring efficient transmission and distribution of electrical energy. The positive and negative poles of the DC bus are two key connection points in a DC power system, representing the high and low potentials of the DC voltage, respectively. "DCBUS+" represents the high potential end (positive pole) of the DC bus, and "DCBUS-" represents the low potential end (negative pole) of the DC bus. Current flows from "DCBUS+" to "DCBUS-." The positive pole of the DC power source is connected to the positive end of the DC bus, the negative pole of the DC power source is connected to the negative end of the DC bus, the positive pole of the load is connected to the positive end of the DC bus, and the negative pole of the load is connected to the negative end of the DC bus.

[0047] Capacitors can be polarized capacitors, also known as polarized capacitors or polarized capacitors. These are capacitors whose internal structure dictates a clear positive and negative polarity. Polarized capacitors must be connected correctly in a circuit; otherwise, they may damage the capacitor or even explode. Polarized capacitors typically consist of the following main components: a positive electrode, the high-potential end of the capacitor; a negative electrode, the low-potential end of the capacitor; an electrolyte, a medium used to store charge; and an insulating layer, a dielectric layer that separates the positive and negative electrodes. The operating principle of polarized capacitors is based on the process of charge storage and release. When a capacitor is connected to a power source, charge accumulates between the positive and negative electrodes, forming an electric field. Polarized capacitors have a high capacitance and can provide a large charge storage capacity in a small size. They are suitable for applications requiring large-capacity capacitors, such as power filtering and energy storage.

[0048] Multiple capacitors 21 are connected in parallel between the positive and negative electrodes of the DC bus 22. The positive electrodes of the multiple capacitors 21 are connected together to form a common positive electrode, and the negative electrodes of the multiple capacitors 21 are connected together to form a common negative electrode. The common positive electrode is connected to the positive electrode of the DC bus 22, and the common negative electrode is connected to the negative electrode of the DC bus 22. The load is connected between the common positive electrode and the common negative electrode. The parallel connection of multiple capacitors 21 can transmit the DC voltage of the DC bus 22 to the bridge switching circuit 10. Connecting multiple capacitors in parallel can effectively filter out ripple and noise in the power supply, improve the stability and reliability of the power supply, provide greater charge storage capacity, meet high energy requirements, reduce equivalent series resistance (ESR), improve reliability, disperse current loads, and improve circuit performance.

[0049] In the present invention, the DC bus circuit 20 further includes a contactor 23; one end of the contactor 23 is connected to the positive electrode of the DC bus 22, and the other end is connected to the bridge switching circuit 10, and is used to control whether the DC voltage at the positive electrode of the DC bus 22 is transmitted to the bridge switching circuit 10. Specifically, one end of the contactor 23 is connected to the output end of the common positive electrode of the multiple capacitors 21 connected in parallel.

[0050] Contactors are used to control the switching of high-current loads in power systems. They are commonly used for motor start / stop / reverse control, as well as for remote control and protection in industrial automation systems. Key features of contactors include their ability to withstand high currents and voltages, and their long mechanical and electrical lifespan. The operating principle of a contactor is based on electromagnetic induction and mechanical motion. In the energized state, when the electromagnetic coil is energized, a magnetic field is generated, attracting the armature, which then closes the contacts, completing the circuit. In the de-energized state, when the electromagnetic coil is de-energized, the magnetic field disappears, and the spring forces the armature back into position, opening the contacts and breaking the circuit. Contactors can withstand high currents and voltages, making them suitable for high-power loads. They also have a long mechanical and electrical lifespan and can withstand frequent switching operations. Contactors can be remotely controlled and automated through the electromagnetic coil, improving production efficiency. Contactors are often used in conjunction with thermal relays for overload protection, safeguarding equipment and system safety.

[0051] In the present utility model, the bridge switching circuit 10 includes a first switching tube 11, a second switching tube 12, a third switching tube 13 and a fourth switching tube 14; the first switching tube 11 and the third switching tube 13 are upper bridge switching tubes, the second switching tube 12 and the fourth switching tube 14 are lower bridge switching tubes, and the first switching tube 11 and the third switching tube 13 are used to receive the DC voltage of the positive pole of the DC bus 22; the second switching tube 12 and the fourth switching tube 14 are used to receive the DC voltage of the negative pole of the DC bus 22.

[0052] The bridge switching circuit 10 may be a full-bridge switching circuit. It should be noted that the switching tube device may be a switching device such as a MOSFET, an IGBT, or a gallium nitride switching tube.

[0053] A full-bridge switching circuit is typically connected across a DC power supply. The circuit's output is connected to the load, and the switching devices control the direction and magnitude of current flow. The DC power supply provides a DC voltage and is typically connected across the full-bridge circuit. The load consumes electrical energy and is typically connected to the full-bridge circuit's output. The control circuit adjusts the on and off times of the switching devices to achieve precise control of voltage and current. The operating principle of a full-bridge switching circuit is based on the periodic on and off cycles of the switching devices. By controlling the on and off times of the switching devices, voltage and current conversion and regulation are achieved.

[0054] In the present invention, the input end of the first switching tube 11 is connected to the positive pole of the DC bus 22, and the output end is connected to the second switching tube 12; the input end of the second switching tube 12 is connected to the negative pole of the DC bus 22, and the output end is connected to the fourth switching tube 14; the input end of the third switching tube 13 is connected between the positive pole of the DC bus 22 and the first switching tube 11, and the output end is connected to the fourth switching tube 14; the input end of the fourth switching tube 14 is connected between the negative pole of the DC bus 22 and the second switching tube 12, and the output end is connected to the third switching tube

[0055] Pipe 13 is connected.

[0056] The first and third switches 11 and 13 are upper-bridge switches, while the second and fourth switches 12 and 14 are lower-bridge switches. The first and fourth switches 11 and 14 form a pair of bridge arms, while the second and third switches 12 and 13 form a pair of bridge arms. A bidirectional inverter power supply bridge circuit typically employs an H-bridge circuit structure, comprising four switches (such as IGBTs or MOSFETs) forming an H-shape, with a DC power supply or energy storage component (such as a battery) in the middle and the two ends connected to an AC load (or grid). There are two operating modes: Inverter mode (DC to AC): When the circuit needs to convert DC power to AC power, the four switches are controlled in a complementary manner to form an AC voltage. Specifically, two diagonal switches (such as the first switch 11 and the fourth switch 14) are turned on simultaneously, and then the other two diagonal switches (the second switch 12 and the third switch 13) are turned on, forming a sine wave or square wave AC output. Rectification mode (AC to DC): When the circuit needs to convert AC to DC, the actual process is to achieve energy rectification and accumulation through diode rectification or active switching of the switches within the circuit. For example, in the positive half cycle of AC, the first switch 11 and the second switch 12 are controlled to be turned on, forming a forward voltage; conversely, in the negative half cycle of AC, the third switch 13 and the fourth switch 14 are controlled to be turned on, forming a reverse voltage, thereby outputting DC.

[0057] In the present invention, the bridge switching circuit 10 includes a first output end 15 and a second output end 16; the first output end 15 is arranged between the first switching tube 11 and the second switching tube 12, and is used to output the AC voltage; the second output end 16 is arranged between the third switching tube 13 and the fourth switching tube 14, and is used to output the AC voltage.

[0058] In the utility model, the alternating current bus circuit 30 includes alternating current bus 31, first inductance 32 and second inductance 33;The alternating current bus 31 includes firewire and zero line;The one end of first inductance 32 is connected with the first output 15, and the other end is connected with the firewire of alternating current bus 31;The one end of second inductance 33 is connected with the second output 16, and the other end is connected with the zero line of alternating current bus 31.

[0059] The alternating current bus usually refers to the common connection point or bus for transmitting alternating current energy in the system. It connects power sources, loads, transformers, circuit breakers and other power equipment, ensuring efficient transmission and distribution of electric energy. The working principle of alternating current bus is based on the following key points: electric energy transmission, alternating current bus as the common path of electric energy transmission, connecting power sources and loads, through alternating current bus, electric energy is transmitted from power sources to loads, ensuring normal operation of loads; Voltage regulation, the voltage on the alternating current bus needs to be kept stable to ensure the normal operation of the load, through the transformer and voltage regulator, the voltage on the alternating current bus can be adjusted to adapt to different load requirements. In order to ensure the safety and reliability of alternating current bus, the following protection measures are usually taken: overvoltage protection, using overvoltage protection devices (such as lightning arresters, voltage-dependent resistors, etc.), to prevent high voltage from damaging equipment; Overcurrent protection, using overcurrent protection devices (such as fuses, circuit breakers, etc.), to prevent excessive current from damaging equipment; Short circuit protection, using short circuit protection devices (such as fuses, circuit breakers, etc.), to prevent short circuit failure from damaging equipment; Insulation protection, using insulation materials and tools to ensure safe operation and prevent electric shock accidents.

[0060] The alternating current bus usually includes firewire (Live Wire) and zero line (Neutral Wire), which are two key components in alternating current power system. Firewire and zero line represent the high potential and low potential of alternating current voltage respectively. Firewire is the high potential end of alternating current voltage, usually represented by "L", providing high potential of electric energy, and current flows from firewire to zero line; Zero line is the low potential end of alternating current voltage, usually represented by "N", providing low potential of electric energy, and current flows from firewire to zero line.

[0061] Inductance is a fundamental component in electrical circuits, used to store and release magnetic field energy. An inductor is an electronic component, typically composed of a coil. When current passes through the coil, a magnetic field is generated around it. Inductors play a variety of important roles in circuits, including filtering, energy storage, signal coupling, and impedance matching. The operating principle of inductance is based on Faraday's Law of Electromagnetic Induction and Lenz's Law. When current passes through an inductor, a magnetic field is generated around it. The change in the magnetic field induces an electromotive force (voltage) in the inductor, thereby hindering the change in current. Inductors are widely used in various electronic devices and systems, including: power filtering, used to filter out ripple and noise in the power supply, improving the stability and reliability of the power supply; energy storage, used to store electrical energy, such as battery charging and discharging, to improve energy utilization efficiency and extend equipment life; signal coupling, used for signal coupling and decoupling, improving signal transmission quality and system stability; impedance matching, used to match the impedance between different circuits, reduce signal reflection and loss, and improve signal transmission efficiency and system performance.

[0062] Reference Figure 3 , shows a schematic structural diagram of a voltage sampling circuit of the present invention, wherein the voltage sampling circuit 40 includes: at least one voltage sampling resistor 41, a first bypass capacitor 42 and a first filter capacitor 43 connected to the voltage sampling resistor 41, and a first operational amplifier 44 having one end connected to the voltage sampling resistor 41 and the other end outputting the voltage sampling signal.

[0063] The voltage sampling circuit 40 is used to sample the voltage of the DC bus circuit 20 and the AC bus circuit 30. The voltage sampling point 411 is as follows: Figure 2 As shown, of course, the specific selection of the voltage sampling point 411 can be adjusted according to actual needs. The first operational amplifier 44 outputs the voltage sampling signal to the main control chip 70, and the detection module 60 can include the main control chip 70.

[0064] A sampling resistor is a resistor used to measure current or voltage. It is commonly used in applications such as current sensing, voltage sensing, and signal conditioning. A sampling resistor measures current indirectly by measuring the voltage drop across it, or by using a voltage divider to adjust the input voltage to fit within the input voltage range of an ADC (analog-to-digital converter). This voltage divider adjusts the input voltage range of the ADC to fit within the ADC's input range. The appropriate resistance value is selected to ensure that the voltage signal at the sampling point accurately reflects the actual voltage value, while also taking into account the input impedance to prevent any impact on the original circuit. Sometimes, a current-limiting resistor is used at the ADC input to prevent damage from excessive input current.

[0065] A bypass capacitor is a capacitor used to bypass high-frequency noise. It's typically connected between the power supply and ground to filter out high-frequency noise, ensuring power supply stability and signal purity. The bypass capacitor's operating principle is based on the capacitor's impedance characteristics. For high-frequency signals, the capacitor's impedance is low, acting as a short circuit, thereby bypassing the high-frequency noise to ground. For low-frequency signals, the capacitor's impedance is high, acting as an open circuit, without affecting the transmission of the low-frequency signal.

[0066] A filter capacitor is a capacitor used to filter out ripple and noise from a power supply. It's typically connected between the power supply output and ground to smooth the output voltage and ensure proper operation of the load. The filter capacitor operates based on the charge and discharge process of the capacitor. When the power supply output voltage fluctuates, the filter capacitor charges and discharges, smoothing the output voltage and reducing ripple and noise.

[0067] Reference Figure 4 , shows a schematic structural diagram of a current sampling circuit of the present invention, the current sampling circuit 50 includes: at least one current sampling resistor 51, a second bypass capacitor 52 and a second filter capacitor 53 connected to the current sampling resistor 51, and a second operational amplifier 54 having one end connected to the current sampling resistor 51 and the other end outputting the current sampling signal.

[0068] The current sampling circuit 50 is used to sample the current of the DC bus circuit 20 and the AC bus circuit 30. The current sampling point 511 is as follows: Figure 2 As shown, of course, the specific selection of the current sampling point 511 can be adjusted according to actual needs, and the second operational amplifier 54 outputs the voltage sampling signal to the main control chip 70.

[0069] The current sampling circuit 50 may also be a current detection amplifier circuit or an integrated current detection circuit.

[0070] In the present utility model, the detection module 60 includes a short-circuit detection module and an oscillation detection module; the short-circuit detection module is used to receive the current sampling signal, and judge whether the bridge switch circuit 10 is short-circuited according to the current sampling signal, and send the judgment result to the main control module 70; the oscillation detection module is used to receive the current sampling signal and the voltage sampling signal, and judge whether the switch tube of the bridge switch circuit 10 is abnormally turned on according to the current sampling signal and the voltage sampling signal, and send the judgment result to the main control module 70.

[0071] The switch tube of the bridge switching circuit 10 may be mis-turned on due to high-frequency oscillation or oscillation caused by the AC load. The short-circuit detection module receives the current sampling signal, preliminarily determines whether the bridge switching circuit 10 is short-circuited based on the current sampling signal, and sends the judgment result to the main control module 70. The oscillation detection module receives the current sampling signal and the voltage sampling signal, and determines whether abnormal oscillation occurs based on the current sampling signal and the voltage sampling signal, whether it causes mis-turning on or whether there is a risk of mis-turning on, and sends the judgment result to the main control module 70.

[0072] In the present invention, the main control module 70 is used to stop sending pulse signals to the bridge switch circuit 10 when the switch tube of the bridge switch circuit 10 is abnormally turned on.

[0073] The main control module 70 performs pulse information control. The main control module 70 performs pulse information control according to the judgment results sent by the short-circuit detection module and the oscillation detection module. Upon receiving the short-circuit and oscillation risk instructions, the main control chip locks the pulse signal and stops sending the pulse signal to the bridge switch circuit 10. The bridge switch circuit 10 will stop working if it does not receive the pulse signal. In this way, the switch tube can be protected in time from being damaged by the spike impact caused by the oscillation and the switching power supply can be protected from being short-circuited, thereby improving the stability and reliability of the switching power supply.

[0074] After the main control module 70 stops sending pulse signals to the bridge switch circuit 10, a self-test procedure is performed after a preset time, and a pre-charge instruction is sent to the bridge switch circuit 10. The voltage sampling circuit 40 and the current sampling circuit 50 sample the voltage and current conditions on the DC bus side and the AC bus side. The oscillation detection module and the short-circuit detection module collect and detect information. If the risk of misconduction is eliminated at this time, the main control chip sends an instruction to make the bridge switch circuit 10 start working again.

[0075] For example, the preset time may be 1 minute, and the self-test procedure may be performed after 1 minute. Of course, the preset time may be set in actual applications according to actual needs, and the present invention does not impose any limitation on this.

[0076] Precharge commands are critical in power electronics, particularly electric vehicles, uninterruptible power supply (UPS) systems, and converters and inverters using large capacitors. It's a control strategy for smoothly starting high-voltage capacitors or batteries, primarily to prevent hardware damage caused by excessive inrush current during system startup. Overview of the Precharge Process: Precharge Resistor: The precharge circuit typically includes a precharge resistor or precharge relay, which forms a high-impedance link between the high-voltage circuit and the capacitor or battery. Startup Phase: When the system starts, the precharge command connects the precharge resistor. This directs current through the resistor rather than directly into the capacitor or battery, limiting the inrush current. Capacitor Charging: Current flows through the precharge resistor, and the capacitor begins to charge steadily. During this process, the capacitor voltage gradually increases until it reaches or approaches the power supply voltage. Normal Operation: When the capacitor voltage reaches a preset value (typically above 90% of the power supply voltage), the precharge resistor is disconnected, and the system enters normal operation. At this point, the main relay or contactor closes, allowing current to flow directly through the capacitor for subsequent operation. Function: Protect circuit components: The pre-charging process can prevent high-voltage capacitors, battery packs or power modules from suddenly bearing a large current shock during cold start, reduce damage to circuit components, and extend service life. Reduce voltage fluctuations: By limiting the initial current, pre-charging can smooth the startup process, avoid large fluctuations in system voltage, and improve system stability and safety. Implementation strategy Pre-charging instructions are usually executed by controller software or automatically triggered by hardware circuits. In complex power electronic systems, the pre-charging process may require precise control and monitoring to ensure that the circuit can not only start safely, but also enter an efficient and stable working state after startup. Usually, the precise execution of pre-charging instructions requires the use of current sensors and voltage sensors to monitor the circuit status, and adjust the pre-charging duration based on feedback to ensure that the capacitor or battery pack reaches normal working state smoothly.

[0077] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device that includes the element.

[0078] The above is a detailed introduction to a detection circuit for abnormal conduction of a switching tube provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for general technical personnel in this field, based on the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A detection circuit for abnormal conduction of a switching tube, characterized in that: include: A bridge switching circuit, a DC bus circuit and an AC bus circuit connected to the bridge switching circuit, a voltage sampling circuit and a current sampling circuit connected to the DC bus circuit and the AC bus circuit respectively, a detection module connected to the voltage sampling circuit and the current sampling circuit respectively, and a main control module connected to the detection module; The bridge switch circuit is used to convert the DC voltage of the DC bus circuit into an AC voltage and transmit the AC voltage to the AC bus circuit; The voltage sampling circuit is used to sample the voltages of the DC bus circuit and the AC bus circuit, and transmit the voltage sampling signals to the detection module; The current sampling circuit is used to sample the current of the DC bus circuit and the AC bus circuit, and transmit the current sampling signal to the detection module; The detection module is configured to determine whether the switch tube of the bridge switch circuit is abnormally turned on based on the voltage sampling signal and the current sampling signal, and send the determination result to the main control module; The main control module is used to determine whether the switch tube of the bridge switch circuit is abnormally turned on based on the judgment result, and when the switch tube of the bridge switch circuit is abnormally turned on, control the bridge switch circuit to stop receiving the DC voltage of the DC bus circuit.

2. The circuit according to claim 1, wherein: The DC bus circuit includes multiple capacitors and a DC bus; the DC bus includes a positive pole and a negative pole; the multiple capacitors are connected in parallel between the positive pole and the negative pole of the DC bus, and are used to transmit the DC voltage of the DC bus to the bridge switching circuit.

3. The circuit according to claim 2, characterized in that The DC bus circuit also includes a contactor; one end of the contactor is connected to the positive pole of the DC bus, and the other end is connected to the bridge switch circuit, which is used to control whether the DC voltage of the positive pole of the DC bus is transmitted to the bridge switch circuit.

4. The circuit according to claim 1, wherein: The bridge switching circuit includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube; the first switching tube and the third switching tube are upper bridge switching tubes, the second switching tube and the fourth switching tube are lower bridge switching tubes, the first switching tube and the third switching tube are used to receive the DC voltage of the positive pole of the DC bus; the second switching tube and the fourth switching tube are used to receive the DC voltage of the negative pole of the DC bus.

5. The circuit according to claim 4, characterized in that The input end of the first switching tube is connected to the positive pole of the DC bus, and the output end is connected to the second switching tube; the input end of the second switching tube is connected to the negative pole of the DC bus, and the output end is connected to the fourth switching tube; the input end of the third switching tube is connected between the positive pole of the DC bus and the first switching tube, and the output end is connected to the fourth switching tube; the input end of the fourth switching tube is connected between the negative pole of the DC bus and the second switching tube, and the output end is connected to the third switching tube.

6. The circuit according to claim 5, characterized in that The bridge switching circuit includes a first output end and a second output end; the first output end is arranged between the first switching tube and the second switching tube, and is used to output the AC voltage; the second output end is arranged between the third switching tube and the fourth switching tube, and is used to output the AC voltage.

7. The circuit according to claim 6, characterized in that The AC bus circuit includes an AC bus, a first inductor and a second inductor; the AC bus includes a live wire and a neutral wire; one end of the first inductor is connected to the first output end, and the other end is connected to the live wire of the AC bus; one end of the second inductor is connected to the second output end, and the other end is connected to the neutral wire of the AC bus.

8. The circuit according to claim 1, wherein: The voltage sampling circuit includes: at least one voltage sampling resistor, a first bypass capacitor and a first filter capacitor connected to the voltage sampling resistor, and a first operational amplifier having one end connected to the voltage sampling resistor and the other end outputting the voltage sampling signal.

9. The circuit according to claim 1, wherein: The current sampling circuit includes: at least one current sampling resistor, a second bypass capacitor and a second filter capacitor connected to the current sampling resistor, and a second operational amplifier having one end connected to the current sampling resistor and the other end outputting the current sampling signal.

10. The circuit according to claim 1, wherein: The detection module includes a short-circuit detection module and an oscillation detection module; the short-circuit detection module is used to receive the current sampling signal, and determine whether the bridge switch circuit is short-circuited based on the current sampling signal, and send the determination result to the main control module; the oscillation detection module is used to receive the current sampling signal and the voltage sampling signal, and determine whether the switch tube of the bridge switch circuit is abnormally turned on based on the current sampling signal and the voltage sampling signal, and send the determination result to the main control module.

11. The circuit according to claim 1, wherein: The main control module is used to stop sending pulse signals to the bridge switch circuit when the switch tube of the bridge switch circuit is abnormally turned on.

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