Current sampling circuit with protection triggering function

Abstract

The utility model discloses a current sampling circuit with a protection trigger function, which relates to the technical field of current sampling circuits, and comprises an inversion module, a load module, a current analog signal sampling module and a chip Core module, the inversion module is connected with the load module and supplies power to the load module; the current analog signal sampling module is connected with the inversion module, and the current analog signal sampling module is used for carrying out current signal sampling on each phase of current after inversion, filtering the sampled current signals after isolation and amplification, and transmitting the filtered current signals to the chip Core module; and the chip Core module is used for processing the received current signal and then displaying the processed current signal on a display terminal or executing an overcurrent protection action, so that the problems that the time for executing the protection action is prolonged and the device cost is increased due to the fact that an existing current sampling circuit needs a comparison and judgment circuit are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of current sampling circuits, in particular to a current sampling circuit with a protection trigger function. Background Art

[0002] In industrial inverters, the current sampling circuit is often one of the indispensable core circuits. It is often used to collect the working current at the output end of the power conversion loop of the product. On the one hand, the collected current value can be amplified by the operational amplifier and processed by the chip, and then presented to the handheld panel end, so that users can understand the current output status of the product. On the other hand, the collected current value can be synchronously transmitted to the subsequent comparison circuit, and the comparator is used to compare and determine whether the inverter is in a normal working state under the current output current value. If the inverter is in an abnormal state such as overcurrent / short circuit under the current output current value, the comparator will output the corresponding signal to the chip end, and then the chip will perform the protection action.

[0003] Since the existing current sampling circuit requires a subsequent comparison and judgment circuit, the total time required to execute the protection action is increased, and the device cost is increased. Utility Model Content

[0004] The utility model provides a current sampling circuit with a protection trigger function, which has the advantages of shortening the total time for executing the protection action, improving the reliability of the frequency converter, and omitting the corresponding comparison and judgment circuit and device at the subsequent stage to save costs, so as to solve the problem that the existing current sampling circuit requires a subsequent comparison and judgment circuit, increases the total time for executing the protection action, and increases the cost of the device.

[0005] In order to shorten the total time for executing protection actions, improve the reliability of the inverter, and save costs by eliminating the corresponding comparison and judgment circuits and devices in the later stage, the utility model provides the following technical solutions: a current sampling circuit with a protection trigger function, including an inverter module, a load module, a current analog signal sampling module and a chip Core module, wherein: the inverter module is used to invert the input high-voltage DC voltage into a three-phase high-voltage AC voltage and then output a three-phase current, the inverter module is connected to the load module to supply power to the load module; the current analog signal sampling module is connected to the inverter module, the current analog signal sampling module is used to sample the current signal of each phase current after inversion, isolate and amplify the sampled current signal, and then filter it, and transmit the filtered current signal to the chip Core module; the chip Core module is used to process the received current signal and present it on the display terminal or perform overcurrent protection actions.

[0006] As a preferred technical solution of the utility model, the inverter module includes a U-phase current output unit, a V-phase current output unit and a W-phase current output unit, and the U-phase current output unit, the V-phase current output unit and the W-phase current output unit each include two IGBT tubes, and the two IGBT tubes in the U-phase current output unit, the V-phase current output unit and the W-phase current output unit are connected, and one of the IGBT tubes is connected to the DC high voltage input V BUS+ Connect another IGBT tube to the DC high voltage input V BUS- The connection points of the two connected IGBT tubes are respectively connected to the load module and the current analog signal sampling module.

[0007] As a preferred technical solution of the utility model, the current analog signal sampling module includes three sampling resistors R SHUNT , three optocouplers TPA8000 / 1 / 2 and three post-stage analog signal filters, the outputs of the U-phase current output unit, the V-phase current output unit and the W-phase current output unit are respectively connected to three sampling resistors R SHUNT After connection, connect to the load module; the three sampling resistors R SHUNT They are respectively connected to three optical couplers TPA8000 / 1 / 2, and the three optical couplers TPA8000 / 1 / 2 are respectively connected to three post-stage analog signal filters, and the three post-stage analog signal filters are all connected to the chip Core module.

[0008] As a preferred technical solution of the utility model, the sampling negative input of the optical coupler TPA8000 / 1 / 2 and the sampling resistor R SHUNT The front end of the optocoupler TPA8000 / 1 / 2 is connected to the sampling positive input and the sampling resistor R SHUNT The back end connection, the sampling resistor R SHUNT The front end is also connected to the ground terminal of the optocoupler TPA8000 / 1 / 2; the optocoupler TPA8000 / 1 / 2 isolates and amplifies the common-mode current sampling signals received by the sampling negative input and the sampling positive input, and then obtains the output PIN pin OUTP and the output PI N pin OUTN by the optocoupler TPA8000 / 1 / 2 and outputs them to the subsequent analog signal filter for filtering.

[0009] As a preferred technical solution of the utility model, a capacitor C1 is connected between the sampling negative input of the optocoupler TPA8000 / 1 / 2 and the sampling positive input of the optocoupler TPA8000 / 1 / 2.

[0010] As a preferred technical solution of the utility model, the load module is a three-phase motor, and each of the three-phase motors is respectively connected to the connection between the two IGBT tubes in the U-phase current output unit, the V-phase current output unit and the W-phase current output unit through a sampling resistor R SHUNT connect.

[0011] As a preferred technical solution of the utility model, the sampling resistor R SHUNT The common mode voltage value V CM After inputting to the optocoupler TPA8000 / 1 / 2, the optocoupler TPA8000 / 1 / 2 isolates and amplifies the common mode voltage V CM Compare and judge: If the common mode voltage value V CM Greater than the protection trigger value V of the optocoupler TPA8000 / 1 / 2 CMOV , then the optocoupler TPA8000 / 1 / 2 will output a set voltage value V FAILSAFE The chip Core module receives the voltage value V output by the optocoupler TPA8000 / 1 / 2 FAILSAFE Then execute the over-current protection action.

[0012] Compared with the prior art, the utility model provides a current sampling circuit with a protection trigger function, which has the following beneficial effects:

[0013] The current sampling circuit with protection trigger function integrates comparison judgment and protection trigger functions to replace the comparison judgment circuit. On the one hand, it can save costs by eliminating the corresponding comparison judgment circuit and devices in the subsequent stage. On the other hand, by performing protection triggering in the sampling circuit instead of the traditional solution of using a comparator for protection triggering, the total time for executing the protection action is shortened, the reliability of the inverter is improved, and the device cost is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of a current sampling circuit module with a protection trigger function of the utility model.

[0015] Figure 2 This is a schematic diagram of the structure of a current sampling circuit with a protection trigger function of the utility model. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] See also Figure 1-Figure 2 The utility model discloses a current sampling circuit with a protection trigger function, including an inverter module, a load module, a current analog signal sampling module and a chip Core module, wherein: the inverter module is used to invert the input high-voltage DC voltage into a three-phase high-voltage AC voltage and then output a three-phase current, the inverter module is connected to the load module to supply power to the load module; the current analog signal sampling module is connected to the inverter module, the current analog signal sampling module is used to sample the current signal of each phase current after inversion, isolate and amplify the sampled current signal, and then filter it, and transmit the filtered current signal to the chip Core module; the chip Core module is used to process the received current signal and present it on the display terminal or perform overcurrent protection action.

[0018] The inverter module inverts the high-voltage DC voltage into a three-phase high-voltage AC voltage and supplies power to the load module. The current analog signal sampling module is connected to the inverter module to sample the current signals of each phase after inversion and transmit the processed signals to the chip Core module. The chip Core module receives the current signal and processes it. The specific functions include presenting the current signal on the display terminal after processing and performing overcurrent protection actions. Through current sampling and processing by the chip Core module, real-time monitoring and analysis of the current can be achieved, thereby improving the safety of the system. Once an overcurrent condition is detected, the chip Core module can perform an overcurrent protection action and cut off the circuit in time to protect the load and equipment.

[0019] Specifically, the inverter module includes a U-phase current output unit, a V-phase current output unit and a W-phase current output unit, each of which includes two IGBT tubes, and the two IGBT tubes in the U-phase current output unit, the V-phase current output unit and the W-phase current output unit are connected, and one of the IGBT tubes is connected to the DC high voltage input V BUS+ Connect another IGBT tube to the DC high voltage input V BUS- The connection points of the two connected IGBT tubes are connected to the load module and the current analog signal sampling module respectively.

[0020] The load module is a three-phase motor. Each phase of the three-phase motor is connected to the connection of two IGBT tubes in the U-phase current output unit, the V-phase current output unit and the W-phase current output unit through a sampling resistor R SHUNT connect.

[0021] In this embodiment, when the external 380V AC power supply is input to the inverter, the inverter front-stage rectifier circuit first rectifies the AC input into a DC high voltage input, namely V BUS+ 、V BUS-The rectified DC high voltage input V BUS+ 、V BUS- Then, three groups of six IGBTs, namely, U-phase upper and lower IGBTs, V-phase upper and lower IGBTs, and W-phase upper and lower IGBTs, are used to invert the current into U-phase current, V-phase current, and W-phase current outputs.

[0022] Before being transmitted to the rear-end motor load (i.e. Motor), the UVW three-phase current will pass through the sampling resistor R on each phase current output line. SHUNT To complete the current sampling function.

[0023] The inverter module includes U-phase, V-phase and W-phase current output units, each of which contains two IGBT tubes. These IGBT tubes are used to invert the input DC high voltage voltage into a three-phase high voltage AC voltage. In each current output unit, two IGBT tubes are connected, one of which is connected to the positive pole (V BUS+ ) and the other connected to the negative pole of the DC high voltage input (V BUS- ) connection. This connection mode can realize power supply to the load. The connection points of the two connected IGBT tubes are connected to the load module and the current analog signal sampling module respectively. This means that the inverter module is connected to the load module through these connections, and is also connected to the current analog signal sampling module to sample and monitor the current signal.

[0024] Specifically, the current analog signal sampling module includes three sampling resistors R SHUNT , three optocouplers TPA8000 / 1 / 2 and three post-stage analog signal filters, the outputs of the U-phase current output unit, the V-phase current output unit and the W-phase current output unit are connected to three sampling resistors R SHUNT After connection, connect to the load module; three sampling resistors R SHUNT They are respectively connected to three optocouplers TPA8000 / 1 / 2, the three optocouplers TPA8000 / 1 / 2 are respectively connected to three post-stage analog signal filters, and the three post-stage analog signal filters are all connected to the chip Core module.

[0025] The sampling negative input of the optocoupler TPA8000 / 1 / 2 and the sampling resistor R SHUNT The front-end connection of the optocoupler TPA8000 / 1 / 2 is connected to the sampling positive input and the sampling resistor R SHUNT The back-end connection, sampling resistor R SHUNT The front end is also connected to the ground terminal of the optocoupler TPA8000 / 1 / 2; the optocoupler TPA8000 / 1 / 2 isolates and amplifies the common-mode current sampling signals received by the sampling negative input and the sampling positive input, and then obtains the output PI N pin OUTP and the output PI N pin OUTN from the optocoupler TPA8000 / 1 / 2 and outputs them to the subsequent analog signal filter for filtering.

[0026] In this embodiment, in the current sampling circuit with trigger protection function, the voltage value at the front end of the sampling resistor is used as the sampling negative input (i.e., V INN ), the voltage value at the back end of the sampling resistor is used as the sampling positive input of the optocoupler TPA8000 / 1 / 2 (i.e. V INP ). Common mode current sampling signal V INN 、V INP After being isolated and amplified by the optocoupler TPA8000 / 1 / 2, the current is outputted to the post-stage analog signal filter Analog Filter through the output pins OUTP and OUTN for filtering. The current sampling signal after filtering is transmitted to the chip Core. After receiving the current sampling signal, the chip Core performs corresponding processing and presents it to the handheld panel or directly performs overcurrent protection action.

[0027] The sampling resistor RSHUNT is used to introduce a small resistor in the current path, so that a voltage drop is generated when the current passes through. This method can achieve accurate sampling of the current because the voltage drop is proportional to the current. By using the sampling resistor, the current signal can be accurately obtained. The optocoupler TPA8000 / 1 / 2 is used to isolate the input and output signals to prevent signal interference and crosstalk. After the sampling signal is isolated and amplified, the stability and accuracy of the signal can be maintained. The post-stage analog signal filter is used to filter the sampling signal to remove possible noise and interference, so as to obtain a more stable and reliable current signal. This ensures that the signal quality received by the chip Core module is good.

[0028] Specifically, a capacitor C1 is connected between the sampling negative input of the optocoupler TPA8000 / 1 / 2 and the sampling positive input of the optocoupler TPA8000 / 1 / 2.

[0029] In this embodiment, capacitor C1 can be used as a filter element to filter out high-frequency noise or interference in the input signal, which helps to ensure a cleaner and more stable signal at the input port of the optocoupler device, thereby improving the quality and reliability of the signal. Capacitor C1 can prevent the DC component from the sampled signal from being transmitted through the optocoupler device, which helps to reduce the DC bias or interference that may exist in the system, thereby improving the stability and reliability of the system.

[0030] Specifically, through the sampling resistor R SHUNT The common mode voltage value V CM After inputting to the optocoupler TPA8000 / 1 / 2, the optocoupler TPA8000 / 1 / 2 isolates and amplifies the common-mode voltage V CM Compare and judge: If the common mode voltage value VCM Greater than the protection trigger value V of the optocoupler TPA8000 / 1 / 2 CMOV , then the optocoupler TPA8000 / 1 / 2 will output a set voltage value V FAILSAFE The chip Core module receives the voltage value V output by the optocoupler TPA8000 / 1 / 2 FAILSAFE Then execute the over-current protection action.

[0031] In this embodiment, the sampling resistor R SHUNT The common mode voltage value V CM After inputting to the optocoupler TPA8000 / 1 / 2, the optocoupler TPA8000 / 1 / 2 will perform isolation and amplification while also comparing and judging the voltage value. CM =(V INN+ V INP ) / 2 is greater than the protection trigger value V of the optocoupler TPA8000 / 1 / 2 CMOV = VDD1-2.4, the optocoupler TPA8000 / 1 / 2 will output a specific voltage value V FAILSAFE , this specific voltage value can be used as a protection trigger mark. After the chip Core receives the protection trigger mark output by this optocoupler TPA8000 / 1 / 2, it can immediately perform the corresponding protection action.

[0032] In summary, compared with the traditional current sampling circuit, the innovation of the current sampling circuit with protection trigger function is to replace the comparison judgment circuit by integrating comparison judgment and protection trigger function, thus shortening the execution time of the protection action and saving the device cost.

[0033] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A current sampling circuit with protection trigger function, It is characterized in that It includes inverter module, load module, current analog signal sampling module and chip Core module, among which: The inverter module is used to invert the input high-voltage DC voltage into a three-phase high-voltage AC voltage and then output a three-phase current. The inverter module is connected to the load module to supply power to the load module; The current analog signal sampling module is connected to the inverter module, and is used to sample the current signal of each phase current after the inverter, filter the sampled current signal after isolation and amplification, and transmit the filtered current signal to the chip Core module; The chip Core module is used to process the received current signal and present it on the display terminal or perform overcurrent protection action.

2. A current sampling circuit with protection trigger function according to claim 1, Features: The inverter module includes a U-phase current output unit, a V-phase current output unit and a W-phase current output unit, each of which includes two IGBT tubes, and two of the IGBT tubes in the U-phase current output unit, the V-phase current output unit and the W-phase current output unit are connected, and one of the IGBT tubes is connected to the DC high voltage input V BUS+ Connect another IGBT tube to the DC high voltage input V BUS- connect; The connection points of the two connected IGBT tubes are respectively connected to the load module and the current analog signal sampling module.

3. A current sampling circuit with protection trigger function according to claim 2, Features: The current analog signal sampling module includes three sampling resistors R SHUNT , three optocouplers TPA8000 / 1 / 2 and three post-stage analog signal filters, the outputs of the U-phase current output unit, the V-phase current output unit and the W-phase current output unit are respectively connected to three sampling resistors R SHUNT After connection, connect with the load module; The three sampling resistors R SHUNT They are respectively connected to three optical couplers TPA8000 / 1 / 2, and the three optical couplers TPA8000 / 1 / 2 are respectively connected to three post-stage analog signal filters, and the three post-stage analog signal filters are all connected to the chip Core module.

4. A current sampling circuit with protection trigger function according to claim 3, Features: The sampling negative input of the optocoupler TPA8000 / 1 / 2 and the sampling resistor R SHUNT The front end of the optocoupler TPA8000 / 1 / 2 is connected to the sampling positive input and the sampling resistor R SHUNT The back end connection, the sampling resistor R SHUNT The front end is also connected to the ground terminal of the optocoupler TPA8000 / 1 / 2; The optical coupler TPA8000 / 1 / 2 isolates and amplifies the common-mode current sampling signals received by the sampling negative input and the sampling positive input, and then obtains the output PIN pin OUTP and the output PIN pin OUTN from the optical coupler TPA8000 / 1 / 2 and outputs them to the subsequent analog signal filter for filtering.

5. A current sampling circuit with protection trigger function according to claim 4, Features: A capacitor C1 is connected between the sampling negative input of the optocoupler TPA8000 / 1 / 2 and the sampling positive input of the optocoupler TPA8000 / 1 / 2.

6. A current sampling circuit with protection trigger function according to claim 3, Features: The load module is a three-phase motor, and each of the three-phase motors is respectively connected to the connection between two IGBT tubes in the U-phase current output unit, the V-phase current output unit and the W-phase current output unit through a sampling resistor R SHUNT connect.

7. A current sampling circuit with protection trigger function according to claim 3, Features: Through the sampling resistor R SHUNT The common mode voltage value V CM After inputting to the optocoupler TPA8000 / 1 / 2, the optocoupler TPA8000 / 1 / 2 isolates and amplifies the common mode voltage V CM Compare and judge: If the common mode voltage value V CM Greater than the protection trigger value V of the optocoupler TPA8000 / 1 / 2 CMOV , then the optocoupler TPA8000 / 1 / 2 will output a set voltage value V FAILSAFE The chip Core module receives the voltage value V output by the optocoupler TPA8000 / 1 / 2 FAILSAFE Then execute the over-current protection action.

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