Relay arcless closing and breaking control device and method

Abstract

The application relates to a relay arcless closing and breaking control device and method, which adopts an IGBT and a contact in parallel form, a relay coil voltage sampling module inputs the coil voltage of the relay as a switch quantity into a microcontroller MCU, is used to judge the movement direction of the relay contact, and thus turns on the corresponding IGBT, an IGBT current signal sampling module is used to judge whether the relay contact current is transferred, a contact voltage sampling circuit is used to judge the IGBT conduction time when the contact is closed, a control signal output module amplifies the output power of the microcontroller MCU pin, turns on the IGBT through an IGBT driving circuit, considering the existence of inductive load overvoltage, an IGBT protection circuit is added to absorb voltage peaks, and a power module realizes power supply for the whole circuit system. The application can realize arcless breaking and closing of the relay, enhances the breaking capacity of the relay, prolongs the electrical life of the relay, and has the advantages of stability and reliability and easy realization.

Description

Technical Field

[0001] This invention belongs to the field of intelligent switching electrical appliances, and in particular relates to a relay arc-free closing and disconnection control device and method. Background Technology

[0002] In the field of switching electrical appliances, mechanical contacts are usually used as devices for switching on and off loads. However, mechanical contacts generate electric arcs when disconnecting loads, which leads to contact erosion, increases the contact resistance of the contacts, increases the thermal effect of the current, and may even cause the contacts to weld. Therefore, the electrical life of traditional mechanical switching electrical appliances is greatly reduced due to the electric arc.

[0003] To address the aforementioned issues, a fully solid-state relay has been designed to avoid arc erosion. However, the switching losses of the fully solid-state relay are relatively large. Since it carries the load current through IGBTs, it generates significant heat, requiring a large heat sink. Furthermore, it is susceptible to damage from overvoltage and overcurrent.

[0004] Therefore, a relay arc-free closing and opening control method is proposed. Compared with the original composite relay, this invention can complete the arc extinguishing process in both closing and opening, further improving the reliability of the relay. However, this method has the following shortcomings: (1) Since IGBT devices are introduced and their action time is necessarily earlier than that of mechanical contacts, this method makes the load turn on earlier or turn off later.

[0005] (2) The cost is high because of the addition of an extra circuit system. Summary of the Invention

[0006] This invention provides a relay arc-free closing and disconnection control device and method to extinguish the electric arc of the relay operation, extend the relay's electrical life, and has the advantages of being stable, reliable, and easy to implement.

[0007] The objective of this invention is achieved by providing a relay arc-free closing and disconnection control device and method, characterized by comprising a microcontroller (MCU), a power supply module, a coil control signal sampling module, an IGBT current sampling module, a contact voltage acquisition circuit, a control signal output module, an IGBT drive circuit, an IGBT module, an IGBT protection circuit, and a rectifier bridge circuit. The microcontroller (MCU) is electrically connected to the output terminals of the coil control signal sampling module, the IGBT current sampling module, and the contact voltage acquisition circuit through interfaces, and is used to receive the electrical signals collected by the coil control signal sampling module, the IGBT current sampling module, and the contact voltage acquisition circuit. The IGBT module consists of two IGBTs, IGBT1 and IGBT2, which are connected in parallel between two pairs of contacts of the relay. The microcontroller (MCU) is configured to execute the following control logic: When the relay coil is detected to be energized by the coil control signal sampling module, the IGBT1 is turned on by the control signal output module. The IGBT1 current is sampled in real time by the IGBT current sampling module. When the sampled current is greater than the preset current threshold, it is determined that the relay contact current has been transferred to IGBT1. After a preset delay, IGBT1 is turned off to complete the interruption and arc extinguishing. The contact voltage is detected in real time by the contact voltage acquisition circuit. When the contact is closed, the contact voltage gradually decreases. When the contact voltage is detected to be less than the preset voltage threshold, IGBT2 is turned on. After a preset delay time, IGBT2 is turned off to complete the arc extinguishing.

[0008] The input terminal of the power supply module is connected to the coil of the relay. The power supply module converts the 24V voltage into ±12V and 5V isolated power supplies to provide power to the microcontroller MCU and IGBT drive circuit, respectively. The input terminal of the contact voltage acquisition circuit is connected in parallel with the relay contacts U2+ and U2-. After differential amplification by the operational amplifier LM358, the output terminal of the operational amplifier LM358 is connected to the microcontroller MCU. Zener diodes are also connected in parallel with the relay contacts U2+ and U2- to limit the input voltage. The IGBT module uses a 1KW25N120T2 MOSFET. The input terminal of the IGBT module is connected to the IGBT drive circuit, and the output terminal is connected in series with the current sensor and then in parallel with the relay contacts. The relay contacts have an IGBT protection circuit. The rectifier bridge circuit can realize the AC / DC universal function and is connected in parallel across the two ends of the IGBT module.

[0009] The input terminal of the coil control signal sampling module is connected to the positive and negative terminals of the coil voltage. After passing through the opto-isolator TLP521, the output terminal of the TLP521 emitter follower is connected to the microcontroller MCU. The coil control signal sampling module is used as a switching input to the microcontroller MCU, and optocouplers are used for isolation and level conversion.

[0010] The input terminal of the IGBT current sampling module is connected in series with the IGBT module, and the output terminal of the IGBT current sampling module is connected to the microcontroller (MCU). There is a Zener diode between the output terminal of the IGBT current sampling module and the microcontroller (MCU) to limit the voltage at the output terminal of the IGBT current sampling module, ensuring that the voltage to the microcontroller (MCU) is less than 5V.

[0011] The IGBT current sampling module includes a Hall current sensor, which is connected in series with the IGBT module. It can detect the current magnitude of the IGBT module and convert it into a voltage signal, which is then sampled by the ADC of the microcontroller MCU.

[0012] The control signal output module uses an integrated circuit SN74LVC2G125DCTR. Its input terminal 1A is connected to the microcontroller MCU, and its output terminal is driven by an IGBT driver circuit. The output terminal of the IGBT driver circuit is connected to the gate of the IGBT.

[0013] The IGBT drive circuit uses a TLP250, which is powered by ±12V. The input terminal is electrically connected to the control signal output module, and the output terminal is connected to the gate of the IGBT module. The IGBT drive circuit is used to drive the IGBT module, and the drive is isolated by an optocoupler to achieve level conversion.

[0014] A relay arc-free closing and disconnection control method, characterized by including the following steps: Step 1: After the relay coil is energized, the power supply module outputs the voltage required by the entire circuit system. The coil control signal sampling module inputs a switching signal to the microcontroller MCU. The microcontroller MCU turns on the IGBT module through the control signal output module. Step 2: The IGBT current sampling module samples the IGBT current and converts the current signal into a voltage signal, which is then converted into a voltage signal by the current sensor and input to the microcontroller MCU. Step 3: Determine the magnitude of the sampled current. If the sampled current is less than the current threshold, the relay contact current does not transfer to IGBT1, and return to Step 2; if the sampled current is greater than the current threshold, the relay contact current transfers to IGBT1, and continue to Step 4. Step 4: When the current of IGBT1 exceeds the current threshold, a delay is initiated; Step 5: Turn off IGBT1 to extinguish the arc during the disconnection process; Step 6: Detect the contact voltage; Step 7: When the contact voltage is detected to be greater than the voltage threshold, return to step 6; when the contact is closed, the contact voltage gradually decreases, and when the contact voltage is detected to be less than the voltage threshold, proceed to step 8; Step 8: Turn on IGBT2; Step 9: After the relay contacts close, the contact resistance of the mechanical contacts is much smaller than the conduction resistance of the IGBT. Applying any delay time to IGBT2 can complete the arc extinguishing process of the closing process. Step 10: Turn off IGBT2. End.

[0015] The present invention has the following advantages: (1) The present invention uses IGBT to transfer the arc current of the relay and extinguish the arc.

[0016] (2) The arc-free control technology described above isolates the high-voltage ground from the low-voltage ground, thereby enhancing stability.

[0017] (3) It can extinguish the arc during the breaking and closing process.

[0018] (4) AC and DC voltage and current are applicable simultaneously.

[0019] In summary, this invention has the characteristics of strong anti-interference ability and ease of implementation.

[0020] The present invention will be further described below with reference to the accompanying drawings of the embodiments. Attached Figure Description

[0021] Figure 1 This is a block diagram of the overall solution of the present invention; Figure 1.1 yes Figure 1 Microcontroller (MCU) circuit diagram; Figure 1.2 yes Figure 1 Medium power supply module; Figure 1.3 yes Figure 1 Intermediate coil control signal sampling module; Figure 1.4 yes Figure 1 IGBT current sampling module; Figure 1.5 yes Figure 1 Middle contact voltage acquisition circuit; Figure 1.6 yes Figure 1 Control signal output module, Figure 1.7 yes Figure 1 IGBT drive circuit; Figure 1.8 It consists of IGBT modules and IGBT protection circuits; Figure 1.9 yes Figure 1 Medium rectifier bridge circuit.

[0022] Figure 2 This is a flowchart of the procedure for this invention; Figure 3 This is a timing diagram of the contact disconnection operation of the present invention; Figure 4 This is a diagram showing the contact closure timing of the present invention.

[0023] In the diagram: 1. Microcontroller (MCU); 2. Power supply module; 3. Coil control signal sampling module; 4. IGBT current sampling module; 5. Contact voltage acquisition circuit; 6. Control signal output module; 7. IGBT drive circuit; 8. IGBT module; 9. IGBT protection circuit. Detailed Implementation

[0024] To further illustrate the technical means adopted by the present invention to achieve its intended purpose, the specific implementation methods, structural features and effects of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, this invention relates to a relay arc-free closing and disconnection control device and method, characterized by comprising a microcontroller MCU1, a power supply module 2, a coil control signal sampling module 3, an IGBT current sampling module 4, a contact voltage acquisition circuit 5, a control signal output module 6, an IGBT drive circuit 7, an IGBT module 8, and an IGBT protection circuit 9. The microcontroller MCU1 is electrically connected to the output terminals of the coil control signal sampling module 3, the IGBT current sampling module 4, and the contact voltage acquisition circuit 5 via interfaces, and is used to receive the electrical signals collected by the coil control signal sampling module 3, the IGBT current sampling module 4, and the contact voltage acquisition circuit 5. The microcontroller MCU1 analyzes and processes the collected signals, and based on the analysis and processing results, the control signal output module 6 provides a control signal to the IGBT drive circuit 7, which drives the IGBT module 8 to work. The IGBT module 8 is supplied with power voltage by a rectifier bridge circuit 10. The IGBT drive circuit 7, the control signal output module 6, and the microcontroller MCU1 are all supplied with low-voltage DC power by the power supply module 2.

[0026] Figure 1.1 The pinout diagram of the microcontroller MCU is provided. The microcontroller MCU is an STM32F103C816, which includes 48 external pins and uses an external 8MHz crystal oscillator to provide the system clock.

[0027] Figure 1.2 The circuit of power supply module 2 is given. The entire circuit system of the present invention is powered by power supply module 2. Power supply module 2 converts the voltage of 24V into the voltage required by the system, including ±12V and 5V. The power supply provides reliable isolation measures.

[0028] like Figure 1.3 As shown, the input terminal of the coil control signal sampling module 3 is connected to the positive and negative terminals of the coil voltage. After passing through the opto-isolator TLP521, the output terminal of the TLP521 emitter follower is connected to the microcontroller MCU1. The coil control signal sampling module 3 is used as a switching input to the microcontroller MCU1, and optocouplers are used for isolation and level conversion.

[0029] like Figure 1.4 As shown, the input terminal of the IGBT current sampling module 4 is connected in series with the IGBT module 8, and the output terminal of the IGBT current sampling module 4 is connected to the microcontroller MCU1. There is a Zener diode between the output terminal of the IGBT current sampling module 4 and the microcontroller MCU1 to limit the voltage at the output terminal of the IGBT current sampling module 4, ensuring that the voltage to the microcontroller MCU1 is less than 5V.

[0030] The IGBT current sampling module 4 includes a Hall current sensor, which is connected in series with the IGBT module. It can detect the current magnitude of the IGBT module and convert it into a voltage signal, which is then sampled by the ADC of the microcontroller MCU1.

[0031] like Figure 1.5 As shown, the input terminal of the contact voltage acquisition circuit 5 is connected in parallel with the relay contacts U2+ and U2-. After differential amplification by the operational amplifier LM358, the output terminal of the operational amplifier LM358 is connected to the microcontroller MCU1. Zener diodes are connected in parallel with the relay contacts U2+ and U2- to limit the input voltage.

[0032] The contact voltage acquisition circuit 5 can reduce large voltages. It has an overvoltage protection device at the input end to prevent excessive voltage from damaging the circuit. In addition, the input end has an RC low-pass filter circuit, which can smooth out the contact voltage that changes too quickly when closed, thus making it easier for the MCU to sample.

[0033] like Figure 1.6 As shown, the control signal output module 6 uses an integrated circuit SN74LVC2G125DCTR. Its input terminal 1A is connected to the microcontroller MCU1, and its output terminal is driven by the IGBT drive circuit 7. The output terminal of the IGBT drive circuit 7 is connected to the gate of the IGBT.

[0034] like Figure 1.7 As shown, the IGBT drive circuit 7 uses a TLP250, which is powered by ±12V. The input terminal is electrically connected to the control signal output module 6, and the output terminal is connected to the gate of the IGBT module. The IGBT drive circuit is used to drive the IGBT module, and the drive is isolated by an optocoupler to achieve level conversion.

[0035] like Figure 1.8As shown, the IGBT module 8 uses a 1KW25N120T2 MOSFET. The input terminal of the IGBT module 8 is connected to the IGBT drive circuit 7, and the output terminal is connected in series with the current sensor and then in parallel with the relay contacts. The relay contacts have an IGBT protection circuit 9. There are two IGBT modules 8, which are connected in parallel between the two pairs of contacts of the relay. The rectifier bridge circuit can realize the AC / DC universal function and is connected in parallel across the two ends of the IGBT module 8.

[0036] The IGBT protection circuit 9 protects the IGBT from breakdown. Considering the presence of inductive load, when the IGBT is turned off, the inductive energy cannot be released, which will generate overvoltage. Therefore, a protection circuit is needed to absorb the energy of the circuit.

[0037] The IGBT control signal output module 6 can amplify the output current of the microcontroller MCU1, making it easier to drive subsequent circuits.

[0038] Figure 2 The flowchart of the arc-free control program of the present invention includes the following steps: Step 1: After the relay coil is energized, the power supply module 2 outputs the voltage required by the entire circuit system. The coil control signal sampling module 3 inputs a switching signal to the microcontroller MCU1. The microcontroller MCU1 turns on the IGBT module 8 through the control signal output module 6. Step 2: The IGBT current sampling module 4 samples the IGBT current and converts the current signal into a voltage signal, which is then converted into a voltage signal by the current sensor and input to the microcontroller MCU1. Step 3: Determine the magnitude of the sampled current. If the sampled current is less than the current threshold, the relay contact current does not transfer to IGBT1, and return to Step 2; if the sampled current is greater than the current threshold, the relay contact current transfers to IGBT1, and continue to Step 4. Step 4: When the current of IGBT1 exceeds the current threshold, a delay is initiated; Step 5: Turn off IGBT1 to extinguish the arc during the disconnection process; Step 6: Detect the contact voltage; Step 7: When the contact voltage is detected to be greater than the voltage threshold, return to step 6; when the contact is closed, the contact voltage gradually decreases, and when the contact voltage is detected to be less than the voltage threshold, proceed to step 8; Step 8: Turn on IGBT2; Step 9: After the relay contacts close, the contact resistance of the mechanical contacts is much smaller than the conduction resistance of the IGBT. Applying any delay time to IGBT2 can complete the arc extinguishing process of the closing process. Step 10: Turn off IGBT2. End.

[0039] Figure 3 The timing diagram of the contact disconnection action of the present invention shows that when the coil is energized, the IGBT immediately has a drive signal, indicating that the IGBT has been turned on. After a period of time, the IGBT current signal is high, indicating that the contact current has been transferred to the IGBT branch. Then, after a delay of about 10ms.

[0040] Figure 4 The timing diagram of the contact closing action of the present invention shows that when the contact is closed, the voltage gradually decreases. When it is less than the threshold voltage, the IGBT drive signal is output to turn on the corresponding IGBT.

[0041] The present invention relates to a relay arc-free closing and disconnection control device and method. The working principle is as follows: Firstly, in the stable state of the relay, the mechanical contacts serve as the main device for carrying the load circuit. When the relay operates, the IGBT of the corresponding contact is turned on when the coil voltage is energized. Since the arc voltage is greater than the IGBT's on-state voltage drop, current will transfer to the IGBT. Considering that the relay has a pair of changeover contacts, to prevent short circuits between the upper and lower contacts, the IGBT current needs to be sampled. When the IGBT current is greater than the threshold, it is determined that the current transfer is complete. Then, to prevent arc reignition, the IGBT is turned off with a delay. When the contacts are closed, the voltage gradually decreases. When it is less than the threshold voltage, an IGBT drive signal is output to turn on the corresponding IGBT. Since the arc energy is released through the IGBT, no arc is generated.

[0042] In summary, the present invention relates to a relay arc-free closing and disconnection control device and method that can extinguish the relay arc, solve the problem of arc erosion, and improve the electrical life of the relay.

[0043] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A relay arc-free closing and disconnection control device, characterized in that: It includes a microcontroller MCU (1), a power supply module (2), a coil control signal sampling module (3), an IGBT current sampling module (4), a contact voltage acquisition circuit (5), a control signal output module (6), an IGBT drive circuit (7), an IGBT module (8), an IGBT protection circuit (9), and a rectifier bridge circuit; The microcontroller MCU (1) is electrically connected to the output terminals of the coil control signal sampling module (3), the IGBT current sampling module (4), and the contact voltage acquisition circuit (5) through an interface, and is used to receive the electrical signals collected by the coil control signal sampling module (3), the IGBT current sampling module (4), and the contact voltage acquisition circuit (5); The IGBT module (8) consists of two IGBTs, namely IGBT1 and IGBT2, which are connected in parallel between two pairs of contacts of the relay; the microcontroller MCU (1) is configured to execute the following control logic: When the relay coil is detected to be energized by the coil control signal sampling module (3), the IGBT1 is turned on by the control signal output module (6); the IGBT1 current is sampled in real time by the IGBT current sampling module (4). When the sampled current is greater than the preset current threshold, it is determined that the relay contact current has been transferred to the IGBT1. After entering the preset delay, the IGBT1 is turned off to complete the interruption and arc extinguishing. The contact voltage is detected in real time by the contact voltage acquisition circuit (5). When the contact is closed, the contact voltage gradually decreases. When the contact voltage is detected to be less than the preset voltage threshold, IGBT2 is turned on. After the preset delay time, IGBT2 is turned off to complete the arc extinguishing. The input terminal of the power supply module (2) is connected to the coil of the relay. The power supply module (2) converts the 24V voltage into ±12V and 5V isolated power supplies to provide power to the microcontroller MCU (1) and the IGBT drive circuit (7), respectively. The input terminal of the contact voltage acquisition circuit (5) is connected in parallel with the relay contacts U2+ and U2-. After differential amplification by the operational amplifier LM358, the output terminal of the operational amplifier LM358 is connected to the microcontroller MCU (1). Zener diodes are connected in parallel with the relay contacts U2+ and U2- to limit the input voltage. The IGBT module (8) uses a 1KW25N120T2 MOSFET. The input terminal of the IGBT module (8) is connected to the IGBT drive circuit (7), and the output terminal is connected in series with the current sensor and then in parallel with the relay contact. The relay contact has an IGBT protection circuit (9). The rectifier bridge circuit can realize the AC / DC universal function and is connected in parallel across the two ends of the IGBT module (8).

2. The relay arc-free closing and disconnection control device according to claim 1, characterized in that: The input terminal of the coil control signal sampling module (3) is connected to the positive and negative terminals of the coil voltage. After passing through the opto-isolator TLP521, the output terminal of the TLP521 emitter follower is connected to the microcontroller MCU (1). The coil control signal sampling module (3) is input to the microcontroller MCU (1) as a switching input, and is isolated and level converted by optocoupler.

3. The relay arc-free closing and disconnection control device according to claim 1, characterized in that: The input terminal of the IGBT current sampling module (4) is connected in series with the IGBT module (8), and the output terminal of the IGBT current sampling module (4) is connected to the microcontroller MCU (1). There is a Zener diode between the output terminal of the IGBT current sampling module (4) and the microcontroller MCU (1) to limit the voltage of the output terminal of the IGBT current sampling module (4) to ensure that the voltage to the microcontroller MCU (1) is less than 5V.

4. The relay arc-free closing and disconnection control device according to claim 1, characterized in that: The IGBT current sampling module (4) includes a Hall current sensor, which is connected in series with the IGBT module (8). It can detect the current magnitude of the IGBT module (8) and convert it into a voltage signal, which is then sampled by the microcontroller MCU (1) using ADC.

5. The relay arc-free closing and disconnection control device according to claim 1, characterized in that: The control signal output module (6) uses an integrated circuit SN74LVC2G125DCTR. Its input terminal 1A is connected to the microcontroller MCU (1), and its output terminal is driven by the IGBT drive circuit (7). The output terminal of the IGBT drive circuit (7) is connected to the gate of the IGBT.

6. The relay arc-free closing and disconnection control device according to claim 1, characterized in that: The IGBT driving circuit (7) uses a TLP250, which is powered by ±12V. Its input terminal is electrically connected to the control signal output module (6), and its output terminal is connected to the gate of the IGBT module (8). The IGBT driving circuit (7) is used to drive the IGBT module (8) and achieves level conversion through optocoupler isolation driving.

7. A relay arc-free closing and disconnection control method, employing the device described in claim 1, characterized in that... Includes the following steps: Step 1: After the relay coil is energized, the power supply module (2) outputs the voltage required by the entire circuit system, and the coil control signal sampling module (3) inputs a switch signal to the microcontroller MCU (1). The microcontroller MCU (1) turns on the IGBT module (8) through the control signal output module (6). Step 2: The IGBT current sampling module (4) samples the IGBT current and converts the current signal into a voltage signal, which is then converted into a voltage signal by the current sensor and input to the microcontroller MCU (1); Step 3: Determine the magnitude of the sampled current. If the sampled current is less than the current threshold, the relay contact current does not transfer to IGBT1, and return to Step 2; if the sampled current is greater than the current threshold, the relay contact current transfers to IGBT1, and continue to Step 4. Step 4: When the current of IGBT1 exceeds the current threshold, a delay is initiated; Step 5: Turn off IGBT1 to extinguish the arc during the disconnection process; Step 6: Detect the contact voltage; Step 7: When the contact voltage is detected to be greater than the voltage threshold, return to step 6; when the contact is closed, the contact voltage gradually decreases, and when the contact voltage is detected to be less than the voltage threshold, proceed to step 8; Step 8: Turn on IGBT2; Step 9: After the relay contacts close, the contact resistance of the mechanical contacts is much smaller than the conduction resistance of the IGBT. Applying any delay time to IGBT2 can complete the arc extinguishing process of the closing process. Step 10: Turn off IGBT2. End.

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