Switching circuit without arc generation during switching during charging of alternating current charging pile

Abstract

The utility model belongs to the field of switch control, and relates to a switching circuit without arc generation during switching when an alternating current charging pile is charged, which comprises a microcontroller, a silicon carbide field effect transistor, a current detection circuit, a driving circuit and a protection circuit, and is characterized in that the microcontroller is connected with the current detection circuit, the driving circuit and the protection circuit through an I / O port, and is used for receiving a current detection signal; a gate electrode of the silicon carbide field effect transistor is connected with a PWM output end of the microcontroller through the driving circuit, a drain electrode of the silicon carbide field effect transistor is connected with a power supply or a load, a source electrode of the silicon carbide field effect transistor is connected with the ground through the protection circuit, and the current detection circuit is connected in series in the switching circuit. The device is used for monitoring the current value in the switching circuit in real time. The energy loss is effectively reduced, the possibility of arc generation can be obviously reduced in the switching process, and the safety and reliability of the system are improved.

Description

Technical Field

[0001] This utility model relates to the field of switch control technology, and more specifically, to a switch circuit that prevents arc generation when the AC charging pile is charging. Background Technology

[0002] The purpose of the arc-free switching circuit in an AC charging station is to prevent the generation of electric arcs when the circuit is disconnected. An electric arc is a discharge phenomenon caused by the ionization of gas molecules or atoms in the contact gap when current flows through a gas or vacuum. The generation of electric arcs can not only damage switching equipment but also affect the stability and safety of the circuit.

[0003] Existing charging stations typically use relays to control the opening and closing of circuits. A drawback is that when the current exceeds eight times the rated current, the relay takes 3-5 milliseconds to separate, generating heat according to Joule's law, which can easily cause the relay contacts to stick together. While current charging stations have a function to detect contact sticking, they lack the ability to separate stuck contacts, thus losing their protective function. What is needed is a switch that can separate within 200µs when the current is extremely high, with the generated heat insufficient to affect the switch's performance, thereby providing protection. Utility Model Content

[0004] To address the aforementioned deficiencies in the prior art, this utility model provides a switching circuit for AC charging piles that prevents arc generation during charging, comprising:

[0005] The system comprises a microcontroller, a silicon carbide field-effect transistor (SiNFET), a current detection circuit, a drive circuit, and a protection circuit. The microcontroller is connected to the current detection circuit, the drive circuit, and the protection circuit via I / O ports to receive current detection signals, output control signals, and monitor the status of the switching circuit in real time. The gate of the SiNFET is connected to the PWM output terminal of the microcontroller through the drive circuit. The drain of the SiNFET is connected to a power supply or load. The source of the SiNFET is connected to ground through the protection circuit. The current detection circuit is connected in series in the switching circuit to monitor the current value in the switching circuit in real time. The drive circuit amplifies the control signal issued by the microcontroller to drive the switching action of the SiNFET. When the microcontroller issues a control signal, the drive circuit amplifies the signal and transmits it to the gate of the SiNFET, thereby controlling the switching action of the switching circuit.

[0006] Preferably, the silicon carbide field-effect transistor includes a first silicon carbide field-effect transistor and a second silicon carbide field-effect transistor, which serve as positive and negative half-cycle switching devices, respectively.

[0007] Preferably, the microcontroller includes any one of the following: STM32 series microcontrollers, ATmega328, Microchip's PIC series microcontrollers, NXP's LPC series microcontrollers, ESP8266, and ESP32.

[0008] Preferably, the silicon carbide field-effect transistor includes any one of C2M, C3M, and C4D.

[0009] Preferably, the current detection circuit includes: a current sensor, a signal conditioning circuit, and an output display circuit.

[0010] Preferably, the driving circuit includes a driving chip.

[0011] Preferably, the protection circuit includes one or more of the following: overcurrent protection circuit, overvoltage protection circuit, and overheat protection circuit.

[0012] Preferably, the overcurrent protection circuit includes: a fast-acting fuse, a current transformer, and an overload circuit breaker.

[0013] Preferably, the overvoltage protection circuit includes: an overvoltage protector, a voltage regulator, and a varistor connected in parallel.

[0014] Preferably, the overheat protection circuit includes a temperature control switch and a heat sink.

[0015] The arc-free switching circuit for AC charging piles implementing this invention offers the following advantages: Using a silicon carbide field-effect transistor (MOSFET) as the switching element, its high switching speed and low on-resistance effectively reduce energy loss and significantly decrease the likelihood of arc generation during switching, thus improving system safety and reliability. The microcontroller is tightly connected to the current detection, drive, and protection circuits via I / O ports, enabling real-time monitoring and precise control of the switching circuit status. The current detection circuit rapidly captures current changes, providing timely feedback to the microcontroller and ensuring the stability and safety of the charging process. The drive circuit amplifies the weak control signals emitted by the microcontroller, sufficient to drive the MOSFETs for reliable switching, ensuring efficient and accurate signal transmission. The addition of the protection circuit provides extra safety for the entire switching circuit, rapidly responding to abnormal current or voltage detection, cutting off the circuit, and preventing equipment damage or fires. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort. The utility model will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0017] Figure 1 This is a schematic diagram of the components of the switching circuit that prevents arc generation during the opening of the AC charging pile of this utility model.

[0018] Figure 2 This is the connection circuit diagram of the first silicon carbide field-effect transistor in the switching circuit of the AC charging pile of this utility model, which prevents arc generation during charging.

[0019] Figure 3 This is the connection circuit diagram of the first silicon carbide field-effect transistor in the switching circuit of the AC charging pile of this utility model, which prevents arc generation during charging. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0023] Please see Figure 1 This is a schematic diagram of the components of the AC charging pile of this utility model, showing that no arc is generated when the circuit breaker is opened during charging. Figure 1 As shown, the switching circuit in the first embodiment of this utility model, which prevents arcing during charging of an AC charging pile, includes at least a microcontroller, a silicon carbide field-effect transistor (SFET), a current detection circuit, a drive circuit, and a protection circuit. The microcontroller is connected to the current detection circuit, the drive circuit, and the protection circuit via an I / O port to receive current detection signals, output control signals, and monitor the status of the switching circuit in real time. The gate of the SFET is connected to the PWM output terminal of the microcontroller via the drive circuit. The drain of the SFET is connected to the power supply or load. The source of the SFET is connected to ground via the protection circuit. The current detection circuit is connected in series in the switching circuit to monitor the current value in the switching circuit in real time. The drive circuit amplifies the control signal issued by the microcontroller to drive the switching action of the SFET. When the microcontroller issues a control signal, the drive circuit amplifies the signal and transmits it to the gate of the SFET, thereby controlling the switching action of its switching circuit.

[0024] The microcontroller (MCU) serves as the control core, responsible for receiving instructions, processing signals, and issuing control commands. In specific implementations, the microcontroller includes, but is not limited to, any of the following: STM32 series microcontrollers, ATmega328, Microchip's PIC series microcontrollers, NXP's LPC series microcontrollers, ESP8266, and ESP32.

[0025] The STM32F103C8T6 uses a high-performance ARM Cortex-M3 32-bit RISC core, operating at 72MHz, and features extensive enhanced I / O and peripherals connected to two APB buses. The STM32U575 is based on a high-performance Arm Cortex-M33 32-bit RISC core, operating at up to 160MHz, offering strong processing performance and power management. The ATmega328 retains the programming ease and community support of the Arduino development platform. Microchip's PIC series MCUs are simple, offer a wide range of models, are low-cost, and easy to use. NXP's LPC series MCUs offer high performance and support for many peripherals. The ESP8266 and ESP32 are widely used in Wi-Fi and Bluetooth-connected IoT applications, offering advantages such as Wi-Fi and Bluetooth integration and low power consumption. In this embodiment, the microcontroller used is the STM32F103C8T6.

[0026] The material characteristics of silicon carbide field-effect transistors (SiC MOSFETs) include:

[0027] High melting point and high hardness: The high melting point and high hardness of silicon carbide materials enable silicon carbide field-effect transistors to withstand higher operating temperatures and harsher environmental conditions, making them suitable for some scenarios with extremely high requirements for device stability.

[0028] High thermal conductivity: Its thermal conductivity is much higher than that of traditional silicon materials, which helps the device maintain stable performance at high temperatures and reduces heat dissipation requirements. It can effectively improve the heat dissipation efficiency of the system and reduce the size and cost of heat dissipation devices.

[0029] High radiation resistance: It has a strong ability to withstand radiation and is suitable for high-radiation environments, such as aerospace, nuclear industry and other fields.

[0030] High-temperature stability: It can maintain stable electrical performance at high temperatures, which broadens its application range in high-temperature environments. For example, silicon carbide field-effect transistors can also work stably in electronic control systems in high-temperature parts such as automobile engine compartments.

[0031] The performance advantages of silicon carbide field-effect transistors include:

[0032] High switching frequency: The switching speed is faster than that of traditional silicon MOSFETs, which can significantly improve the switching frequency of power electronic systems, thereby reducing the size of components such as inductors and capacitors, improving system efficiency, and facilitating the miniaturization and weight reduction of power electronic systems.

[0033] Low loss: It has low switching and conduction losses, which helps to improve the overall efficiency of the system, reduce energy consumption, and perform well in energy saving.

[0034] High blocking voltage and avalanche capability: It can withstand higher voltage and current surges and can be applied to high-voltage, high-power power electronic conversion applications, such as high-voltage direct current transmission and high-power motor drives.

[0035] In specific implementation, silicon carbide field-effect transistors include, but are not limited to, any one of C2M, C3M, and C4D.

[0036] C2M is a low-resistance, high-speed, and low-switching-loss SiC MOSFET output stage field-effect transistor. It is suitable for high-frequency and high-current applications, especially those requiring high efficiency and high speed. Furthermore, the C2M model has a high voltage withstand capability, up to 1200V.

[0037] The C3M is a high-performance SiC MOSFET. Compared to traditional Si MOSFETs, the C3M model offers higher switching speeds and lower switching losses, effectively improving power conversion efficiency and system performance. This model has a wide range of applications, including electric vehicles and solar inverters.

[0038] The C4D model is a type of silicon carbide diode (SBD) that can be combined with Si MOSFETs to form a half-bridge circuit, improving the overall efficiency and performance of the module. The C4D model features lower forward resistance and higher switching speed, making it well-suited for high-temperature, high-voltage, and high-frequency applications.

[0039] Examples include C2M0025120D and C2M0040120D from the C2M series, C3M0065090J from the C3M series, and C4D20120D from the C4D series.

[0040] In practice, the silicon carbide field-effect transistor includes a first silicon carbide field-effect transistor and a second silicon carbide field-effect transistor, which serve as positive and negative half-cycle switching devices, respectively.

[0041] Figure 2 This is the circuit diagram of the first silicon carbide field-effect transistor in the switching circuit of the AC charging pile of this utility model, which prevents arc generation during charging. Figure 2 As shown, the first silicon carbide field-effect transistor connection circuit includes: the gate of silicon carbide field-effect transistor Q1 is connected to one end of resistor R15 and one end of resistor R1 respectively, the other end of resistor R15 is grounded, the source of silicon carbide field-effect transistor Q1 is connected to the drain of silicon carbide field-effect transistor Q2, the gate of silicon carbide field-effect transistor Q2 is connected to one end of resistor R5 and one end of resistor R3 respectively, the other end of resistor R5 is grounded, and the other end of resistor R3 is connected to the other end of resistor R1.

[0042] Figure 3 This is the circuit diagram of the first silicon carbide field-effect transistor in the switching circuit of the AC charging pile of this utility model, which prevents arc generation during charging. Figure 3 As shown, the second silicon carbide field-effect transistor connection circuit includes: the gate of silicon carbide field-effect transistor Q3 is connected to one end of resistor R51 and one end of resistor R2 respectively, the other end of resistor R51 is grounded, the source of silicon carbide field-effect transistor Q3 is connected to the drain of silicon carbide field-effect transistor Q4, the gate of silicon carbide field-effect transistor Q4 is connected to one end of resistor R6 and one end of resistor R4 respectively, the other end of resistor R6 is grounded, and the other end of resistor R4 is connected to the other end of resistor R2.

[0043] Two silicon carbide field-effect transistors (SiC MOSFETs): These serve as the main switching devices, responsible for switching the circuit on and off under the influence of control signals. In this embodiment, both the first SiC MOSFET, such as Q1, and the second SiC MOSFET, such as Q2, are C2M0025120D.

[0044] The current detection circuit monitors the current value in the circuit in real time and converts it into a voltage signal or digital signal for processing by the MCU. In specific implementations, the current detection circuit may include: a current sensor, a signal conditioning circuit, and an output display circuit.

[0045] Current sensors can be resistive, Hall effect, or magnetoelectric, among others. Hall effect sensors are widely used due to their advantages such as wide measurement range, high accuracy, and good linearity. Hall effect sensors operate based on the Hall principle, detecting the Hall-induced electromotive force and then outputting the current signal through a built-in control circuit and power supply.

[0046] The signal conditioning circuit is responsible for amplifying, filtering, and linearizing the signal output from the current sensor for subsequent measurement and display. Factors such as noise suppression, accuracy improvement, and dynamic range need to be considered to ensure signal accuracy and stability.

[0047] The output display circuit converts the conditioned signal into a form that people can intuitively perceive, such as a digital display or waveform display. It should meet the requirements of ease of observation, high accuracy, and good stability, so that users can understand the current status in the circuit in real time.

[0048] The working principle of a current detection circuit is based on Ohm's law and the principle of electromagnetic induction. When current flows through a resistor or wire, a voltage drop is generated, and this voltage drop is directly proportional to the current flowing through it. Therefore, the magnitude of the current flowing through it can be calculated by measuring this voltage drop. The current sensor uses specific physical effects (such as the Hall effect) to convert the current signal into a voltage signal, which is then processed and amplified by a signal conditioning circuit, and finally displayed by an output display circuit.

[0049] In practical implementation, the drive circuit includes a driver chip used to amplify the control signals from the MCU to drive the switching action of the silicon carbide MOSFET. The driver chip also features electrical isolation to prevent interference from the high-voltage circuit to the low-voltage control circuit. Driver chips include, but are not limited to, IVCR1401 / 2, IVCR1412, and IVCO1A0x, which are compact, high-speed, and intelligent, specifically designed to ensure the safe, reliable, and efficient operation of SiC MOSFETs.

[0050] The working principle of the drive circuit is as follows:

[0051] Control signal input: When a control signal from the MCU is input to the driver chip, the driver chip converts it into a gate voltage signal suitable for driving the SiC MOSFET.

[0052] Gate voltage control involves applying a gate voltage signal to the gate of the SiC MOSFET through a gate resistor, thereby altering the electric field distribution in the insulating layer (typically silicon dioxide) beneath the gate. When the gate voltage exceeds a certain threshold (threshold voltage), a conductive channel is formed between the source and drain, allowing current to flow.

[0053] The switching action, controlled by adjusting the gate voltage, enables the SiC MOSFET to be turned on and off. In the on state, current flows from the source to the drain through the conductive channel; in the off state, the conductive channel disappears, and the current is blocked.

[0054] The protection mechanism includes a protection circuit in the drive circuit that can monitor the operating status of the SiC MOSFET in real time and quickly cut off the power supply in case of abnormal conditions such as overcurrent, overvoltage, or overtemperature to protect the device from damage.

[0055] The protection circuit includes one or more of the following: overcurrent protection circuit, overvoltage protection circuit, and overheat protection circuit.

[0056] Overcurrent protection is an important component of protection circuits. When the current in a circuit increases abnormally, the overcurrent protection circuit responds quickly to prevent damage to circuit components due to current overload. Overcurrent protection circuits include: fast-acting fuses, current transformers, and overload circuit breakers.

[0057] A fast-acting fuse, a current transformer, and an overload circuit breaker are connected in series in the switching circuit of this AC charging pile, which operates without arcing during charging. When the current exceeds a set value, they quickly disconnect the circuit, thus protecting it from overcurrent. Its working principle is based on the thermal and magnetic effects of current, and it achieves this by detecting the current magnitude and triggering the corresponding protection mechanism.

[0058] Overvoltage protection is used to prevent the voltage in a circuit from exceeding the rated voltage that the equipment can withstand. An overvoltage protection circuit includes an overvoltage protector, a voltage regulator, and a varistor connected in parallel. When the voltage exceeds a set value, they activate a protection mechanism to limit the voltage within a safe range. For example, when the voltage exceeds its threshold, the resistance of a varistor drops sharply, thereby absorbing and suppressing the overvoltage.

[0059] Overheat protection is used to prevent components in a circuit from overheating and being damaged. Overheat protection circuits include temperature switches and heat sinks. The temperature switch and heat sink are closely connected to the components that need protection. When the temperature exceeds a set value, the temperature switch cuts off the circuit, while the heat sink dissipates heat through fins, fans, etc., thereby maintaining the component's temperature within a safe range.

[0060] The working principle of the switching circuit of this utility model AC charging pile, which prevents arc generation during charging, is as follows:

[0061] During normal charging, the MCU outputs a control signal via the PWM module to drive the gate of the SiC MOSFET, turning it on and allowing current to flow through the circuit. Simultaneously, the current detection circuit monitors the current value in the circuit in real time and converts it into a voltage signal for the MCU to process.

[0062] When the current in the circuit exceeds a preset threshold, the voltage signal output by the current detection circuit will exceed the comparator's threshold voltage, triggering the overcurrent protection circuit. At this time, the protection circuit will quickly disconnect the circuit or reduce the output voltage / current to prevent equipment damage or safety accidents.

[0063] When circuit breaking is required, the MCU sends a control signal to rapidly reduce the gate voltage of the SiC MOSFET, thus switching it from the on state to the off state. Because the SiC MOSFET has high switching speed and low on-resistance, circuit breaking can be achieved in a very short time (e.g., within 200µs), and the generated heat is insufficient to affect the switching performance, avoiding the generation of electric arcs.

[0064] The beneficial effects of this invention, through the design of the above embodiments, are as follows: Using a silicon carbide field-effect transistor (MOSFET) as the switching element, thanks to its high switching speed and low on-resistance, effectively reduces energy loss and significantly reduces the possibility of arcing during switching, thus improving system safety and reliability. The microcontroller is closely connected to the current detection, drive, and protection circuits via I / O ports, enabling real-time monitoring and precise control of the switching circuit status. The current detection circuit can quickly capture current changes, providing timely feedback to the microcontroller and ensuring the stability and safety of the charging process. The drive circuit amplifies the weak control signal emitted by the microcontroller, sufficient to drive the MOSFET for reliable switching action, ensuring efficient and accurate signal transmission. The addition of the protection circuit provides extra safety for the entire switching circuit, enabling rapid response and circuit disconnection upon detection of abnormal current or voltage, preventing equipment damage or fires.

[0065] This utility model has been described based on specific embodiments, but those skilled in the art will understand that various changes and equivalent substitutions can be made without departing from the scope of this utility model. Furthermore, to adapt to specific applications of this utility model, numerous modifications can be made without departing from its protection scope. Therefore, this utility model is not limited to the specific embodiments disclosed herein, but includes all embodiments falling within the protection scope of the claims.

Claims

1. A switching circuit for an AC charging pile that prevents arc generation during charging, characterized in that, include: The system comprises a microcontroller, a silicon carbide field-effect transistor (SiNFET), a current detection circuit, a drive circuit, and a protection circuit. The microcontroller is connected to the current detection circuit, the drive circuit, and the protection circuit via I / O ports to receive current detection signals, output control signals, and monitor the status of the switching circuit in real time. The gate of the SiNFET is connected to the PWM output terminal of the microcontroller through the drive circuit. The drain of the SiNFET is connected to a power supply or load. The source of the SiNFET is connected to ground through the protection circuit. The current detection circuit is connected in series in the switching circuit to monitor the current value in the switching circuit in real time. The drive circuit amplifies the control signal issued by the microcontroller to drive the switching action of the SiNFET. When the microcontroller issues a control signal, the drive circuit amplifies the signal and transmits it to the gate of the SiNFET, thereby controlling the switching action of the switching circuit.

2. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 1, characterized in that, The silicon carbide field-effect transistor includes a first silicon carbide field-effect transistor and a second silicon carbide field-effect transistor, which serve as positive and negative half-cycle switching devices, respectively.

3. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 1, characterized in that, The microcontrollers include any one of the following: STM32 series microcontrollers, ATmega328, Microchip's PIC series microcontrollers, NXP's LPC series microcontrollers, ESP8266, and ESP32.

4. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 1, characterized in that, The silicon carbide field-effect transistor includes any one of C2M, C3M, and C4D.

5. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 1, characterized in that, The current detection circuit includes: a current sensor, a signal conditioning circuit, and an output display circuit.

6. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 1, characterized in that, The driving circuit includes a driving chip.

7. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 1, characterized in that, The protection circuit includes one or more of the following: overcurrent protection circuit, overvoltage protection circuit, and overheat protection circuit.

8. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 7, characterized in that, The overcurrent protection circuit includes: a fast-acting fuse, a current transformer, and an overload circuit breaker.

9. The switching circuit for AC charging piles that prevents arc generation during charging as described in claim 8, characterized in that, The overvoltage protection circuit includes an overvoltage protector, a voltage regulator, and a varistor connected in parallel.

10. The switching circuit for AC charging piles that generates no arc during charging, as described in claim 9, is characterized in that... The overheat protection circuit includes a temperature control switch and a heat sink.

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