Voltage calibration system of frequency converter

Abstract

The invention provides a voltage calibration system of a frequency converter. A data transmission channel is established between automatic test equipment and a remote control cloud platform through a communication device; parameters of the automatic test equipment are set through the remote control cloud platform, and the automatic test equipment is controlled to collect the bus voltage of the frequency converter and the output voltage of the control port and visualize the bus voltage and the output voltage; performing parameter adjustment on the frequency converter according to the acquired bus voltage, the control port output voltage, the read bus voltage of the frequency converter and the read control port output voltage, so that the difference value between the bus voltage displayed by the frequency converter and the acquired bus voltage is smaller than a preset voltage threshold value; enabling the difference value between the control port output voltage displayed by the frequency converter and the acquired control port output voltage to be smaller than a preset voltage threshold value; the purposes of automatic acquisition, calibration and detection are achieved, production safety accidents are reduced, and personal safety guarantee is provided for production operators.

Description

Technical Field

[0001] The invention relates to the technical field of frequency converter voltage testing, and in particular to a voltage calibration system for a frequency converter. Background Art

[0002] The bus voltage and control port output voltage of the inverter are very critical parameters in the inverter signal detection system. They are directly involved in the inverter control algorithm, and the accuracy of the bus voltage and control port output voltage detection determines the performance of the inverter.

[0003] Most inverters are not calibrated before leaving the factory. Some are completely tested by technicians. Each time a machine is tested, it is necessary to use a digital multimeter to measure the actual voltage and compare it with the inverter display voltage to get the difference between the two. The bus voltage percentage of the inverter is adjusted to achieve the purpose of bus voltage calibration and control port output voltage balance. However, this method increases labor costs and time costs, and is prone to errors. In particular, when technicians measure high voltage with an electric pen every time, it poses a certain risk to human safety. Summary of the invention

[0004] The present invention provides a voltage calibration system for a frequency converter, which aims to solve the problem that the frequency converter needs to be manually measured and calibrated for the bus voltage and the control port output voltage before leaving the factory, and the calibration result is easy to be inaccurate.

[0005] In order to achieve the above object, the present invention provides a voltage calibration system for a frequency converter, comprising: an automatic testing device, a communication device and a remote control cloud platform;

[0006] The communication device is used to establish a data transmission channel between the automatic test equipment and the remote control cloud platform;

[0007] Remote control cloud platform, used to set parameters of automatic test equipment through data transmission channel, and control the automatic test equipment to collect the bus voltage of the inverter and the output voltage of the control port;

[0008] The remote control cloud platform is also used to visualize the data received through the data transmission channel;

[0009] Automatic testing equipment, used for collecting the bus voltage and control port output voltage of the inverter, adjusting the parameters of the inverter according to the collected bus voltage and control port output voltage, so that the difference between the bus voltage displayed by the inverter and the collected bus voltage is less than a preset voltage threshold, and the difference between the control port output voltage displayed by the inverter and the collected control port output voltage is less than a preset voltage threshold;

[0010] The automatic test equipment is also used to read the inverter's bus voltage and control port output voltage.

[0011] More specifically, the automatic test equipment includes:

[0012] The acquisition module is used to acquire the bus voltage and control port output voltage of the inverter;

[0013] Calibration module;

[0014] The input end of the acquisition module is electrically connected to the bus voltage output end of the frequency converter and the three-phase voltage output end of the frequency converter respectively, the output end of the acquisition module is electrically connected to the input end of the calibration module, and the output end of the calibration module is connected to the frequency converter signal;

[0015] The bus voltage displayed by the inverter is read through the calibration module, the bus voltage collected by the acquisition module is compared with the bus voltage displayed by the inverter, and the system parameters of the inverter are adjusted according to the comparison result to obtain the bus voltage calibration result of the inverter;

[0016] The control port output voltage displayed by the inverter is read through the calibration module, the control port output voltage collected by the acquisition module is compared with the control port output voltage displayed by the inverter, and the inverter parameters are calibrated according to the comparison result to obtain the control port output voltage calibration result of the inverter.

[0017] Furthermore, the sampling module includes a bus voltage sampling circuit.

[0018] The bus voltage sampling circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first capacitor, a second capacitor, a first switching diode, a second switching diode, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, an operational amplifier, a third capacitor, a thirteenth resistor and a fourth capacitor.

[0019] The first resistor, the second resistor, the third resistor and the fourth resistor are connected in sequence, the first end of the first resistor is connected to the bus voltage output terminal P+ of the inverter, the second end of the fourth resistor is connected to the first end of the first capacitor, the first end of the second capacitor, the third end of the first switching diode, the first end of the tenth resistor, and the fifth input terminal of the operational amplifier, the second end of the second capacitor is connected to the second end of the ninth resistor and to the signal ground, and the first end of the ninth resistor is connected to the second end of the tenth resistor.

[0020] The fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor are connected in sequence, the first end of the fifth resistor is connected to the bus voltage output terminal N of the inverter, the second end of the eighth resistor is respectively connected to the second end of the first capacitor, the third end of the second switching diode, the sixth input terminal of the operational amplifier, the first end of the eleventh resistor, and the first end of the third capacitor, the second end of the third capacitor is respectively connected to the second end of the twelfth resistor, the seventh output terminal of the operational amplifier, and the first end of the thirteenth resistor, the first end of the twelfth resistor is connected to the second end of the eleventh resistor, the second end of the thirteenth resistor is respectively connected to the input terminal of the calibration module and the first end of the fourth capacitor, and the second end of the fourth capacitor is connected to the signal ground.

[0021] Furthermore, the sampling module also includes a three-phase output voltage detection circuit.

[0022] The three-phase output voltage detection circuit includes: a UV phase detection circuit and a VW phase detection circuit.

[0023] The UV phase detection circuit includes: a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a fifth capacitor, a sixth capacitor, a third switching diode, a fourth switching diode, a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a twenty-fifth resistor, a seventh capacitor, a twenty-sixth resistor, an eighth capacitor, an eleventh rectifier diode, a twelfth rectifier diode, a thirteenth rectifier diode, a fourteenth rectifier diode, a ninth capacitor, a tenth capacitor and a twenty-seventh resistor.

[0024] The fourteenth resistor, the fifteenth resistor, the sixteenth resistor and the seventeenth resistor are connected in sequence, the first end of the fourteenth resistor is connected to the U phase of the three-phase voltage output terminal of the inverter, the second end of the seventeenth resistor is respectively connected to the first end of the fifth capacitor, the first end of the sixth capacitor, the third end of the third switching diode, the first end of the twenty-third resistor, and the ninth input terminal of the operational amplifier, the second end of the sixth capacitor is connected to the second end of the twenty-second resistor and to the signal ground, and the first end of the twenty-second resistor is connected to the second end of the twenty-third resistor.

[0025] The eighteenth resistor, the nineteenth resistor, the twentieth resistor and the twenty-first resistor are connected in sequence. The first end of the eighteenth resistor is connected to the V phase of the three-phase voltage output terminal of the inverter. The second end of the twenty-first resistor is respectively connected to the second end of the fifth capacitor, the tenth input terminal of the operational amplifier, the third end of the fourth switching diode, the first end of the twenty-fourth resistor, and the first end of the seventh capacitor. The second end of the twenty-fourth resistor is connected to the first end of the twenty-fifth resistor. The second end of the twenty-fifth resistor is respectively connected to the second end of the seventh capacitor, the eighth output terminal of the operational amplifier, and the first end of the twenty-sixth resistor. The second end of the twenty-sixth resistor is respectively connected to the first end of the eighth capacitor, the tenth input terminal of the thirteenth rectifier diode, and the first end of the thirteenth rectifier diode. The first end of the 13th rectifier diode is connected to the second end of the 14th rectifier diode, the second end of the eighth capacitor is connected to the signal ground, the first end of the 14th rectifier diode is connected to the second end of the 12th rectifier diode and to the signal ground, the second end of the 13th rectifier diode is respectively connected to the second end of the 13th rectifier diode, the first end of the 14th rectifier diode, the first end of the 14th rectifier diode is respectively connected to the first end of the 13th rectifier diode, the second end of the 14th capacitor, the negative electrode of the 14th capacitor, the first end of the 14th rectifier diode is respectively connected to the first end of the 12th rectifier diode, the second end of the 14th capacitor, the negative electrode of the 14th capacitor, the first end of the 14th rectifier diode and the input end of the calibration module.

[0026] The VW phase detection circuit includes: a twenty-eighth resistor, a twenty-ninth resistor, a thirtieth resistor, a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, an eleventh capacitor, a twelfth capacitor, a fifth switching diode, a sixth switching diode, a thirty-sixth resistor, a thirty-seventh resistor, a thirty-eighth resistor, a thirty-ninth resistor, a thirteenth capacitor, a fortieth resistor, a fourteenth capacitor, a fifteenth rectifier diode, a sixteenth rectifier diode, a seventeenth rectifier diode, an eighteenth rectifier diode, a fifteenth capacitor, a sixteenth capacitor, and a forty-first resistor.

[0027] The twenty-eighth resistor, the twenty-ninth resistor, the thirtieth resistor, and the thirty-first resistor are connected in sequence. The first end of the twenty-eighth resistor is connected to the V phase of the three-phase voltage output terminal of the inverter. The second end of the thirty-first resistor is respectively connected to the first end of the eleventh capacitor, the first end of the twelfth capacitor, the third end of the fifth switching diode, the first end of the thirty-seventh resistor, and the twelfth input terminal of the operational amplifier. The second end of the twelfth capacitor is connected to the second end of the thirty-sixth resistor and to the signal ground. The first end of the thirty-sixth resistor is connected to the second end of the thirty-seventh resistor.

[0028] The thirty-second resistor, the thirty-third resistor, the thirty-fourth resistor and the thirty-fifth resistor are connected in sequence. The first end of the thirty-second resistor is connected to the W phase of the three-phase voltage output terminal of the inverter. The second end of the thirty-fifth resistor is respectively connected to the second end of the eleventh capacitor, the third end of the sixth switch diode, the thirteenth input terminal of the operational amplifier, the first end of the thirty-eighth resistor, and the first end of the thirteenth capacitor. The second end of the thirty-eighth resistor is connected to the first end of the thirty-ninth resistor. The second end of the thirty-ninth resistor is respectively connected to the second end of the thirteenth capacitor, the fourteenth output terminal of the operational amplifier, and the first end of the fortieth resistor. The second end of the fortieth resistor is respectively connected to the fourteenth resistor. The first end of the capacitor, the first end of the seventeenth rectifier diode, and the second end of the eighteenth rectifier diode are connected, the second end of the fourteenth capacitor is connected to the signal ground, the first end of the fifteenth rectifier diode is connected to the second end of the sixteenth rectifier diode and to the signal ground, the second end of the fifteenth rectifier diode is respectively connected to the second end of the seventeenth rectifier diode, the first end of the fifteenth capacitor, the positive electrode of the sixteenth capacitor, the second end of the forty-first resistor, and the input end of the calibration module, and the first end of the sixteenth rectifier diode is respectively connected to the first end of the eighteenth rectifier diode, the second end of the fifteenth capacitor, the negative electrode of the sixteenth capacitor, the first end of the forty-first resistor, and the input end of the calibration module.

[0029] Further, the calibration module is a PLC controller with a built-in calibration algorithm. The PLC controller includes a voltage input terminal and a communication terminal. The PLC controller includes a voltage input terminal and a communication terminal. The voltage input terminal includes a UDC port, a UV+ port, a UV- port, a VW+ port, a VW- port and an AD port. The UDC port is connected to the second end of the thirteenth resistor, and is used to receive the bus voltage collected by the bus voltage sampling circuit to input into the PLC controller. The UV+ port is connected to the second end of the twenty-seventh resistor, and the UV- port is connected to the first end of the twenty-seventh resistor, and is used to receive the output voltage of the UV two-phase collected by the UV phase detection circuit. The VW+ port is connected to the second end of the forty-first resistor, and the VW- port is connected to the first end of the forty-first resistor, and is used to receive the output voltage of the VW two-phase collected by the VW phase detection circuit. The AD port is connected to the AO output port of the inverter and is grounded.

[0030] The communication terminal of the PLC controller is connected to the inverter to read the bus voltage and control port output voltage displayed by the inverter, and compare the bus voltage collected by the acquisition module with the bus voltage displayed by the inverter according to the calibration algorithm built into the PLC controller, and calculate the difference between the two. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the bus voltage calibration result of the inverter; the control port output voltage collected by the acquisition module is compared with the control port output voltage displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the control port output voltage calibration result of the inverter.

[0031] Further, the automatic test equipment also includes a power supply boost adjustable module;

[0032] The input end of the power boost adjustable module is connected to the power supply, and the output end of the power boost adjustable module is connected to the input end of the frequency converter.

[0033] Further, the automatic test equipment also includes a switching power supply module;

[0034] The input end of the switching power supply module is connected to the power supply, and the output end of the switching power supply module is connected to the input end of the sampling module and the input end of the calibration module.

[0035] Furthermore, the automatic test equipment also includes a screen display module;

[0036] The input end of the screen display module is connected to the output end of the switch power supply module and the output end of the calibration module respectively.

[0037] Specifically, when the operating frequency of the inverter is less than 15 Hz, the output voltage of the control port is a low-potential voltage. The low-potential voltage value collected by the acquisition module is compared with the low-potential voltage value displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the low-voltage calibration result of the inverter.

[0038] When the operating frequency of the inverter is greater than 40Hz, the output voltage of the control port is a high-potential voltage. The high-potential voltage value collected by the acquisition module is compared with the high-potential voltage value displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the high voltage calibration result of the inverter.

[0039] The above scheme of the present invention has the following beneficial effects:

[0040] The present invention establishes a data transmission channel between an automatic test device and a remote control cloud platform through a communication device; sets parameters of the automatic test device through the remote control cloud platform, controls the automatic test device to collect the bus voltage and control port output voltage of the inverter, and visualizes the data received through the data transmission channel; collects the bus voltage and control port output voltage of the inverter by using the automatic test device, and adjusts the parameters of the inverter according to the collected bus voltage, control port output voltage and the read bus voltage and control port output voltage of the inverter, so that the difference between the bus voltage displayed by the inverter and the collected bus voltage is less than a preset voltage threshold, and the difference between the control port output voltage displayed by the inverter and the collected control port output voltage is less than a preset voltage threshold; the purpose of automatic collection, calibration and detection is achieved, and the time is shorter and the accuracy is higher than that of manual calibration and detection adopted in the prior art, thereby improving production efficiency and product quality. At the same time, the early measurement after production assembly no longer exposes people to high-voltage electricity, reduces the occurrence of production safety accidents, and provides personal safety protection for production operators.

[0041] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a principle block diagram of an embodiment of the present invention;

[0043] Figure 2 A module connection diagram of an automatic test device in an embodiment of the present invention;

[0044] Figure 3 A bus voltage sampling circuit diagram of an embodiment of the present invention;

[0045] Figure 4 A three-phase output voltage UV phase detection circuit diagram of an embodiment of the present invention;

[0046] Figure 5 A three-phase output voltage VW phase detection circuit diagram according to an embodiment of the present invention;

[0047] Figure 6 FIG. 4 is a connection diagram of a calibration module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] In view of the existing problems, the present invention provides a voltage calibration system for a frequency converter.

[0053] like Figure 1 As shown, an embodiment of the present invention provides a voltage calibration system for a frequency converter, comprising: an automatic testing device, a communication device and a remote control cloud platform;

[0054] The communication device is used to establish a data transmission channel between the automatic test equipment and the remote control cloud platform;

[0055] Remote control cloud platform, used to set parameters of automatic test equipment through data transmission channel, and control the automatic test equipment to collect the bus voltage of the inverter and the output voltage of the control port;

[0056] The remote control cloud platform is also used to visualize the data received through the data transmission channel;

[0057] Automatic testing equipment, used for collecting the bus voltage and control port output voltage of the inverter, adjusting the parameters of the inverter according to the collected bus voltage and control port output voltage, so that the difference between the bus voltage displayed by the inverter and the collected bus voltage is less than a preset voltage threshold, and the difference between the control port output voltage displayed by the inverter and the collected control port output voltage is less than a preset voltage threshold;

[0058] The automatic test equipment is also used to read the inverter's bus voltage and control port output voltage.

[0059] In the embodiments of the present invention, it should be noted that the remote control platform is sampled from a conventional remote management platform, and can realize basic equipment parameter settings, data visualization display, issuing control instructions to operators and other functions; the communication device can be a simple serial port line, or it can be a wireless communication unit integrated in the automatic test equipment, such as a WiFi component, a Bluetooth component, a 4G module and other wireless communication units with the ability to transmit data, or it can be a communication device with data exchange capabilities such as a switch.

[0060] Specifically, if Figure 2 As shown, the automatic test equipment includes:

[0061] The acquisition module is used to acquire the bus voltage and control port output voltage of the inverter;

[0062] A calibration module is used to adjust the system parameters of the inverter to calibrate the bus and control port output voltage of the inverter;

[0063] The input end of the acquisition module is electrically connected to the bus voltage output end of the frequency converter and the three-phase voltage output end of the frequency converter respectively, the output end of the acquisition module is electrically connected to the input end of the calibration module, and the output end of the calibration module is connected to the frequency converter signal;

[0064] The bus voltage displayed by the inverter is read through the calibration module, the bus voltage collected by the acquisition module is compared with the bus voltage displayed by the inverter, and the system parameters of the inverter are adjusted according to the comparison result to obtain the bus voltage calibration result of the inverter;

[0065] The control port output voltage displayed by the inverter is read through the calibration module, the control port output voltage collected by the acquisition module is compared with the control port output voltage displayed by the inverter, and the inverter parameters are calibrated according to the comparison result to obtain the control port output voltage calibration result of the inverter.

[0066] In an embodiment of the present invention, the acquisition module sends the collected bus voltage and control port output voltage to the calibration module. The calibration module establishes communication with the inverter through the RS-485 interface and reads the bus voltage and control port output voltage displayed by the inverter. The bus voltage (control port output voltage) collected by the acquisition module is input into the calibration module for comparison with the bus voltage (control port output voltage) displayed by the inverter, and the system parameters of the inverter are adjusted according to the comparison result, so that the difference between the bus voltage (control port output voltage) displayed by the inverter and the bus voltage (control port output voltage) collected by the acquisition module is less than a preset voltage threshold, and whether the three-phase output voltages are balanced in pairs is detected.

[0067] Specifically, if Figure 3 As shown, the sampling module includes a bus voltage sampling circuit, including: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a second capacitor C2, a first switch diode D1, a second switch diode D2, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, an operational amplifier U1D, a third capacitor C3, a thirteenth resistor R13 and a fourth capacitor C4.

[0068] Specifically, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are connected in sequence, the first end of the first resistor R1 is connected to the bus voltage output terminal P+ of the inverter, the second end of the fourth resistor R4 is connected to the first end of the first capacitor C1, the first end of the second capacitor C2, the third end of the first switch diode D1, the first end of the tenth resistor R10, and the fifth input terminal of the operational amplifier U1D, the second end of the second capacitor C2 is connected to the second end of the ninth resistor R9 and connected to the signal ground, the first end of the ninth resistor R9 is connected to the second end of the tenth resistor R10; the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are connected in sequence, and the fifth resistor R5 is connected to the first end of the ninth resistor R9. The first end is connected to the bus voltage output terminal N of the inverter, the second end of the eighth resistor R8 is respectively connected to the second end of the first capacitor C1, the third end of the second switching diode D2, the sixth input terminal of the operational amplifier U1D, the first end of the eleventh resistor R11, and the first end of the third capacitor C3, the second end of the third capacitor C3 is respectively connected to the second end of the twelfth resistor R12, the seventh output terminal of the operational amplifier U1D, and the first end of the thirteenth resistor R13, the first end of the twelfth resistor R12 is connected to the second end of the eleventh resistor R11, the second end of the thirteenth resistor R13 is respectively connected to the input end of the calibration module and the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is connected to the signal ground.

[0069] In the embodiment of the present invention, the bus voltage of the inverter bus voltage output terminal P+ is input to the fifth input terminal of the operational amplifier U1D after being stepped down by the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 connected in series, and the bus voltage of the inverter bus voltage output terminal N is input to the sixth input terminal of the operational amplifier U1D after being stepped down by the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8 connected in series, and the noise between the inverter voltage output terminals P+ and N is filtered out by the first capacitor C1, and the first end of the eleventh resistor R11 and the twelfth resistor R12 connected in series is connected to the bus voltage step-down circuit of the bus voltage output terminal N and the sixth input terminal of the operational amplifier U1D, and the eleventh resistor R11 and the twelfth resistor R12 are connected in series. The second end after connection is connected to the seventh output terminal of the operational amplifier U1D, the first switch diode D1 and the second switch diode D2 are ±15V clamps to protect the operational amplifier U1D from being damaged by excessively high input voltage, and the function of the third resistor C3 is to suppress the self-oscillation of the circuit, wherein the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are all 1M, and the resistance values ​​of the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12 are all 20K, and the entire circuit constitutes a differential negative feedback circuit, and the output voltage is filtered by the thirteenth resistor R13 for current limiting and the fourth capacitor C4 and then input into the calibration module.

[0070] Specifically, the sampling module also includes a three-phase output voltage detection circuit, which includes: a UV phase detection circuit for detecting UV phases of the three-phase output voltage of the transformer and a VW phase detection circuit for detecting VW phases of the three-phase output voltage of the transformer.

[0071] Specifically, if Figure 4 As shown, the UV phase detection circuit includes: a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a fifth capacitor C5, a sixth capacitor C6, a third switch diode D3, a fourth switch diode D4, a twenty-second resistor R22, a twenty-third resistor R23, a twenty-fourth resistor R24, a twenty-fifth resistor R25, a seventh capacitor C7, a twenty-sixth resistor R26, an eighth capacitor C8, an eleventh rectifier diode D11, a twelfth rectifier diode D12, a thirteenth rectifier diode D13, a fourteenth rectifier diode D14, a ninth capacitor C9, a tenth capacitor C10 and a twenty-seventh resistor R27.

[0072] Specifically, the fourteenth resistor R14, the fifteenth resistor R15, the sixteenth resistor R16 and the seventeenth resistor R17 are connected in sequence, the first end of the fourteenth resistor R14 is connected to the U phase of the three-phase voltage output end of the inverter, the second end of the seventeenth resistor R17 is respectively connected to the first end of the fifth capacitor C5, the first end of the sixth capacitor C6, the third end of the third switch diode D3, the first end of the twenty-third resistor R23, and the ninth input end of the operational amplifier U1D, the second end of the sixth capacitor C6 is connected to the second end of the twenty-second resistor R22 and connected to the signal ground, and the twenty-second The first end of the resistor R22 is connected to the second end of the twenty-third resistor R23; the eighteenth resistor R18, the nineteenth resistor R19, the twentieth resistor R20 and the twenty-first resistor R21 are connected in sequence, the first end of the eighteenth resistor R18 is connected to the V phase of the three-phase voltage output end of the inverter, the second end of the twenty-first resistor R21 is respectively connected to the second end of the fifth capacitor C5, the tenth input end of the operational amplifier U1D, the third end of the fourth switch diode D4, the first end of the twenty-fourth resistor R24, and the first end of the seventh capacitor C7, the second end of the twenty-fourth resistor R24 ​​is connected to A first end of a twenty-fifth resistor R25 is connected, a second end of the twenty-fifth resistor R25 is respectively connected to the second end of the seventh capacitor C7, the eighth output end of the operational amplifier U1D, and the first end of a twenty-sixth resistor R26, a second end of the twenty-sixth resistor R26 is respectively connected to the first end of the eighth capacitor C8, the first end of the thirteenth rectifier diode D13, and the second end of the fourteenth rectifier diode D14, a second end of the eighth capacitor C8 is connected to the signal ground, a first end of the eleventh rectifier diode D11 is connected to the second end of the twelfth rectifier diode D12 and is also connected to the signal ground, and the eleventh rectifier diode D12 is connected to the first end of the twelfth rectifier diode D13 and is also connected to the signal ground. The second end of the rectifier diode D11 is respectively connected to the second end of the thirteenth rectifier diode D13, the first end of the ninth capacitor C9, the positive electrode of the tenth capacitor C10, the second end of the twenty-seventh resistor R27, and the input end of the calibration module; the first end of the thirteenth rectifier diode D13 is connected to the second end of the fourteenth rectifier diode D14; the first end of the fourteenth rectifier diode D14 is respectively connected to the first end of the twelfth rectifier diode D12, the second end of the ninth capacitor C9, the negative electrode of the tenth capacitor C10, the first end of the twenty-seventh resistor R27, and the input end of the calibration module.

[0073] In the embodiment of the present invention, the U-phase voltage of the inverter is stepped down by the fourteenth resistor R14, the fifteenth resistor R15, the sixteenth resistor R16, and the seventeenth resistor R17 connected in series, and then input to the ninth input terminal of the operational amplifier U1D. The V-phase voltage of the inverter is stepped down by the eighteenth resistor R18, the nineteenth resistor R19, the twentieth resistor R20, and the twenty-first resistor R21 connected in series, and then input to the tenth input terminal of the operational amplifier U1D. The noise between the U-phase and the V-phase of the inverter is filtered out by the fifth capacitor C5. The first end of the twenty-fourth resistor R24 ​​and the twenty-fifth resistor R25 connected in series is connected to the step-down circuit of the V-phase voltage and the tenth input terminal of the operational amplifier U1D. The second end of the twenty-fourth resistor R24 ​​and the twenty-fifth resistor R25 connected in series is connected to the eighth output terminal of the operational amplifier U1D. The third switch diode D3 and the fourth switch diode D4 are clamped at ±15V to protect the operational amplifier U1D from being damaged by the excessively high input voltage. The function of the seventh resistor C7 is to suppress the self-excitation of the circuit. Oscillation, wherein the resistance values ​​of the fourteenth resistor R14, the fifteenth resistor R15, the sixteenth resistor R16, the seventeenth resistor R17, the eighteenth resistor R18, the nineteenth resistor R19, the twentieth resistor R20, and the twenty-first resistor R21 are all 1M, and the resistance values ​​of the twenty-second resistor R22, the twenty-third resistor R23, the twenty-fourth resistor R24, and the twenty-fifth resistor R25 are all 20K, and the whole circuit constitutes a differential negative feedback circuit, and the output voltage passes through the twenty-sixth resistor R26 and the twenty-third resistor R27 for current limiting. After filtering by the eighth capacitor C8, the square wave is converted into a sine wave. Since the calibration module cannot receive negative signals and sine wave signals and can only receive 0-10V DC signals, the sine wave is full-wave rectified through the eleventh rectifier diode D11, the twelfth rectifier diode D12, the thirteenth rectifier diode D13, and the fourteenth rectifier diode D14, and then filtered by the ninth capacitor C9 and the tenth capacitor C10 and input into the calibration module to realize the voltage detection between the U and V phases in the three-phase output end of the inverter.

[0074] Specifically, if Figure 5 As shown, the VW phase detection circuit includes: a twenty-eighth resistor R28, a twenty-ninth resistor R29, a thirtieth resistor R30, a thirty-first resistor R31, a thirty-second resistor R32, a thirty-third resistor R33, a thirty-fourth resistor R34, a thirty-fifth resistor R35, an eleventh capacitor C11, a twelfth capacitor C12, a fifth switch diode D5, a sixth switch diode D6, a thirty-sixth resistor R36, a thirty-seventh resistor R37, a thirty-eighth resistor R38, a thirty-ninth resistor R39, a thirteenth capacitor C13, a fortieth resistor R40, a fourteenth capacitor C14, a fifteenth rectifier diode D15, a sixteenth rectifier diode D16, a seventeenth rectifier diode D17, an eighteenth rectifier diode D18, a fifteenth capacitor C15, a sixteenth capacitor C16, and a forty-first resistor R41.

[0075] Specifically, the twenty-eighth resistor R28, the twenty-ninth resistor R29, the thirtieth resistor R30, and the thirty-first resistor R31 are connected in sequence, the first end of the twenty-eighth resistor R28 is connected to the V phase of the three-phase voltage output end of the inverter, the second end of the thirty-first resistor R31 is respectively connected to the first end of the eleventh capacitor C11, the first end of the twelfth capacitor C12, the third end of the fifth switch diode D5, the first end of the thirty-seventh resistor R37, and the twelfth input end of the operational amplifier U1D, the second end of the twelfth capacitor C12 is connected to the second end of the thirty-sixth resistor R36 The first end of the thirty-sixth resistor R36 is connected to the signal ground, the first end of the thirty-seventh resistor R37 is connected to the second end of the thirty-seventh resistor R37; the thirty-second resistor R32, the thirty-third resistor R33, the thirty-fourth resistor R34 and the thirty-fifth resistor R35 are connected in sequence, the first end of the thirty-second resistor R32 is connected to the W phase of the three-phase voltage output end of the inverter, the second end of the thirty-fifth resistor R35 is respectively connected to the second end of the eleventh capacitor C11, the third end of the sixth switch diode D6, the thirteenth input end of the operational amplifier U1D, the first end of the thirty-eighth resistor R38, the thirteenth capacitor C1 3, the second end of the thirty-eighth resistor R38 is connected to the first end of the thirty-ninth resistor R39, the second end of the thirty-ninth resistor R39 is respectively connected to the second end of the thirteenth capacitor C13, the fourteenth output terminal of the operational amplifier U1D, and the first end of the fortieth resistor R40, the second end of the fortieth resistor R40 is respectively connected to the first end of the fourteenth capacitor C14, the first end of the seventeenth rectifier diode D17, and the second end of the eighteenth rectifier diode D18, the second end of the fourteenth capacitor C14 is connected to the signal ground, the first end of the fifteenth rectifier diode D15 is connected to the signal ground, and the first end of the fifteenth rectifier diode D15 is connected to the signal ground. The second end of the sixteenth rectifier diode D16 is connected to the signal ground, the second end of the fifteenth rectifier diode D15 is respectively connected to the second end of the seventeenth rectifier diode D17, the first end of the fifteenth capacitor C15, the positive electrode of the sixteenth capacitor C16, the second end of the forty-first resistor R41, and the input end of the calibration module, and the first end of the sixteenth rectifier diode D16 is respectively connected to the first end of the eighteenth rectifier diode D18, the second end of the fifteenth capacitor C15, the negative electrode of the sixteenth capacitor C16, the first end of the forty-first resistor R41, and the input end of the calibration module.

[0076] In the embodiment of the present invention, the V-phase voltage of the inverter is stepped down by the series-connected twenty-eighth resistor R28, the twenty-ninth resistor R29, the thirtieth resistor R30, and the thirty-first resistor R31 and then input to the twelfth input terminal of the operational amplifier U1D. The W-phase voltage of the inverter is stepped down by the series-connected thirty-second resistor R32, the thirty-third resistor R33, the thirty-fourth resistor R34, and the thirty-fifth resistor R35 and then input to the thirteenth input terminal of the operational amplifier U1D. The clutter between the V-phase and the W-phase of the inverter is filtered out by the eleventh capacitor C11. The first end of the series-connected thirty-eighth resistor R38 and the thirty-ninth resistor R39 is connected to the step-down circuit of the V-phase voltage and the thirteenth input terminal of the operational amplifier U1D. The second end of the series-connected thirty-eighth resistor R38 and the thirty-ninth resistor R39 is connected to the fourteenth output terminal of the operational amplifier U1D. The fifth switch diode D5 and the sixth switch diode D6 are ±15V clamps to protect the operational amplifier U1D from being damaged by an excessively high input voltage. The function of the thirteenth capacitor C13 is to suppress the circuit. Self-excited oscillation, wherein the resistance values ​​of the twenty-eighth resistor R28, the twenty-ninth resistor R29, the thirtieth resistor R30, the thirty-first resistor R31, the thirty-second resistor R32, the thirty-third resistor R33, the thirty-fourth resistor R34, and the thirty-fifth resistor R35 are all 1M, and the resistance values ​​of the thirty-sixth resistor R36, the thirty-seventh resistor R37, the thirty-eighth resistor R38, and the thirty-ninth resistor R39 are all 20K, and the whole circuit constitutes a differential negative feedback circuit, and the output voltage passes through the fortieth resistor R40 for current limiting. After filtering by the fourteenth capacitor C14, the square wave is converted into a sine wave. Since the calibration module cannot receive negative signals and sine wave signals and can only receive 0-10V DC signals, the sine wave is full-wave rectified through the fifteenth rectifier diode D15, the sixteenth rectifier diode D16, the seventeenth rectifier diode D17, and the eighteenth rectifier diode D18, and then filtered by the fifteenth capacitor C15 and the sixteenth capacitor C16 and input into the calibration module to realize the voltage detection between the V and W phases in the three-phase output terminal of the inverter.

[0077] Specifically, the first switch diode D1 , the second switch diode D2 , the third switch diode D3 , the fourth switch diode D4 , the fifth switch diode D5 and the sixth switch diode D6 all use the model MMBD7000LT1.

[0078] Specifically, the operational amplifier U1D uses the model LF347, which is a commonly used monolithic quad op amp compatible with field-effect tubes and bipolar tubes. Its advantages are high input impedance, high conversion rate, adjustable internal offset voltage, low offset current, low harmonic distortion, low noise, etc. The main characteristic parameters include power supply voltage ±12V, differential mode voltage gain of 100dB, input offset voltage of 3mV, common mode rejection ratio of 100dB, input resistance of 1012Ω, conversion rate of 13V / us, and unity gain bandwidth of 4MHz.

[0079] Specifically, if Figure 6 As shown, the calibration module is a programmable calibration module, and the programmable calibration module is specifically a PLC controller with a built-in calibration algorithm. The PLC controller includes a voltage input terminal and a communication terminal. The voltage input terminal includes a UDC port, a UV+ port, a UV- port, a VW+ port, a VW- port and an AD port. The UDC port is connected to the second end of the thirteenth resistor R13, and is used to receive the bus voltage collected by the bus voltage sampling circuit and input into the PLC controller. The UV+ port is connected to the second end of the twenty-seventh resistor R27, and the UV- port is connected to the first end of the twenty-seventh resistor R27, and is used to receive the output voltage of the UV two-phase collected by the UV phase detection circuit. The VW+ port is connected to the second end of the forty-first resistor R41, and the VW- port is connected to the first end of the forty-first resistor R41, and is used to receive the output voltage of the VW two-phase collected by the VW phase detection circuit. The AD port is connected to the AO output port of the inverter and is grounded, and is used to read the control port output voltage of the inverter.

[0080] In an embodiment of the invention, the voltage difference threshold value pre-set by the PLC controller is 5V. The communication end of the PLC controller is connected to the frequency converter to read the bus voltage and control port output voltage displayed by the frequency converter, and compare the read bus voltage (control port output voltage) with the received bus voltage (control port output voltage) through the calibration algorithm built into the PLC controller to calculate the difference between the two. When the difference is greater than 5V (0.5V), the system parameters of the frequency converter are adjusted so that the difference is less than 5V (0.5V).

[0081] Specifically, when the operating frequency of the inverter is less than 15Hz, the output voltage of the control port is a low-potential voltage. The low-potential voltage value collected by the acquisition module is compared with the low-potential voltage value displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the low-voltage calibration result of the inverter.

[0082] When the operating frequency of the inverter is greater than 40Hz, the output voltage of the control port is a high-potential voltage. The high-potential voltage value collected by the acquisition module is compared with the high-potential voltage value displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the high voltage calibration result of the inverter.

[0083] In the embodiment of the present invention, the low potential voltage may be 0.1 to 4V, and the high potential voltage may be 7 to 9V.

[0084] In an embodiment of the present invention, the frequency converter inputs a voltage value corresponding to an operating frequency of 15 Hz to an AD interface of a calibration module. The voltage value is converted by a circuit inside the calibration module and compared with a low voltage reference value preset by the frequency converter. The system parameters of the frequency converter are adjusted based on the comparison result, thereby realizing low voltage calibration of the AO port of the frequency converter; the frequency converter inputs a voltage value corresponding to an operating frequency of 40 Hz to an AD interface of the calibration module. The voltage value is converted by a circuit inside the calibration module and compared with a high voltage reference value preset by the frequency converter. The system parameters of the frequency converter are adjusted based on the comparison result, thereby realizing high voltage calibration of the AO port of the frequency converter.

[0085] In order to verify whether the high and low voltages are calibrated successfully, the embodiment of the present invention uses a digital multimeter to test the voltage output by the inverter AO port at an operating frequency of 1 to 50 Hz, and the test values ​​are shown in Table 1 below:

[0086] Table 1

[0087] Operating frequency (Hz) Test value (voltage V) Theoretical value (voltage V) 1 0.205 0.2 2 0.403 0.4 3 0.603 0.6 4 0.802 0.8 5 1.001 1 10 1.997 2 15 2.997 3 20 3.988 4 25 4.99 5 30 5.98 6 35 6.98 7 40 7.98 8 45 8.97 9 50 9.97 10

[0088] It can be seen from Table 1 that after the AO output port is calibrated with high and low voltages, the test value is very close to the theoretical value.

[0089] Specifically, an embodiment of the present invention also includes a power boost adjustable module for supplying power to the inverter. The power boost adjustable module adopts an adjustable boost transformer. The input end of the adjustable boost transformer is connected to the power supply, and the output end of the adjustable boost transformer is connected to the input end of the inverter. The power supply is 220V AC.

[0090] Specifically, an embodiment of the present invention also includes a switching power supply module for providing power to the sampling module and the calibration module, which has protection functions such as overcurrent, overheating, and short circuit. The input end of the switching power supply module is connected to the power supply, and the output end of the switching power supply module is connected to the input end of the sampling module and the input end of the calibration module.

[0091] Specifically, an embodiment of the present invention also includes a screen display module, the input end of the screen display module is respectively connected to the output end of the switching power supply module and the output end of the calibration module; the screen display module is used to set the difference threshold between the bus voltage (control port output voltage) actually sampled by the inverter and the received bus voltage (control port output voltage), and display the calibration results and the detection results of the three-phase output voltage of the inverter.

[0092] The present invention establishes a data transmission channel between an automatic test device and a remote control cloud platform through a communication device; sets parameters of the automatic test device through the remote control cloud platform, controls the automatic test device to collect the bus voltage and control port output voltage of the inverter, and visualizes the data received through the data transmission channel; collects the bus voltage and control port output voltage of the inverter by using the automatic test device, and adjusts the parameters of the inverter according to the collected bus voltage, control port output voltage and the read bus voltage and control port output voltage of the inverter, so that the difference between the bus voltage displayed by the inverter and the collected bus voltage is less than a preset voltage threshold, and the difference between the control port output voltage displayed by the inverter and the collected control port output voltage is less than a preset voltage threshold; the purpose of automatic collection, calibration and detection is achieved, and the time is shorter and the accuracy is higher than that of manual calibration and detection adopted in the prior art, thereby improving production efficiency and product quality. At the same time, the early measurement after production assembly no longer exposes people to high-voltage electricity, reduces the occurrence of production safety accidents, and provides personal safety protection for production operators.

[0093] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A voltage calibration system for a frequency converter, characterized in that: include: Automatic testing equipment, communication devices and remote control cloud platform; The communication device is used to establish a data transmission channel between the automatic test equipment and the remote control cloud platform; The remote control cloud platform is used to set parameters of the automatic test equipment through the data transmission channel, and control the automatic test equipment to collect the bus voltage and control port output voltage of the inverter; The remote control cloud platform is also used to visualize the data received through the data transmission channel; The automatic testing device is used to collect the bus voltage and control port output voltage of the inverter, and adjust the parameters of the inverter according to the collected bus voltage and control port output voltage, so that the difference between the bus voltage displayed by the inverter and the collected bus voltage is less than a preset voltage threshold, and the difference between the control port output voltage displayed by the inverter and the collected control port output voltage is less than a preset voltage threshold; The automatic test equipment is also used to read the bus voltage and control port output voltage of the inverter.

2. The voltage calibration system for a frequency converter according to claim 1, characterized in that: The automatic test equipment comprises: The acquisition module is used to acquire the bus voltage and control port output voltage of the inverter; Calibration module; The input end of the acquisition module is electrically connected to the bus voltage output end of the inverter and the three-phase voltage output end of the inverter respectively, the output end of the acquisition module is electrically connected to the input end of the calibration module, and the output end of the calibration module is connected to the inverter signal; The bus voltage displayed by the inverter is read by the calibration module, the bus voltage collected by the acquisition module is compared with the bus voltage displayed by the inverter, and the system parameters of the inverter are adjusted according to the comparison result to obtain the bus voltage calibration result of the inverter; The control port output voltage displayed by the inverter is read through the calibration module, the control port output voltage collected by the acquisition module is compared with the control port output voltage displayed by the inverter, and the parameters of the inverter are calibrated according to the comparison result to obtain the control port output voltage calibration result of the inverter.

3. The voltage calibration system for a frequency converter according to claim 2, characterized in that: The sampling module includes a bus voltage sampling circuit; The bus voltage sampling circuit includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first capacitor, a second capacitor, a first switch diode, a second switch diode, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, an operational amplifier, a third capacitor, a thirteenth resistor and a fourth capacitor; The first resistor, the second resistor, the third resistor and the fourth resistor are connected in sequence, the first end of the first resistor is connected to the bus voltage output terminal P+ of the inverter, the second end of the fourth resistor is connected to the first end of the first capacitor, the first end of the second capacitor, the third end of the first switch diode, the first end of the tenth resistor, and the fifth input terminal of the operational amplifier, the second end of the second capacitor is connected to the second end of the ninth resistor and to the signal ground, and the first end of the ninth resistor is connected to the second end of the tenth resistor; The fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor are connected in sequence, the first end of the fifth resistor is connected to the bus voltage output terminal N of the inverter, the second end of the eighth resistor is respectively connected to the second end of the first capacitor, the third end of the second switch diode, the sixth input terminal of the operational amplifier, the first end of the eleventh resistor, and the first end of the third capacitor, the second end of the third capacitor is respectively connected to the second end of the twelfth resistor, the seventh output terminal of the operational amplifier, and the first end of the thirteenth resistor, the first end of the twelfth resistor is connected to the second end of the eleventh resistor, the second end of the thirteenth resistor is respectively connected to the input terminal of the calibration module and the first end of the fourth capacitor, and the second end of the fourth capacitor is connected to the signal ground.

4. The voltage calibration system for a frequency converter according to claim 3, characterized in that: The sampling module also includes a three-phase output voltage detection circuit; The three-phase output voltage detection circuit comprises: a UV phase detection circuit and a VW phase detection circuit; The UV phase detection circuit includes: a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a twentieth resistor, a twenty-first resistor, a fifth capacitor, a sixth capacitor, a third switching diode, a fourth switching diode, a twenty-second resistor, a twenty-third resistor, a twenty-fourth resistor, a twenty-fifth resistor, a seventh capacitor, a twenty-sixth resistor, an eighth capacitor, an eleventh rectifier diode, a twelfth rectifier diode, a thirteenth rectifier diode, a fourteenth rectifier diode, a ninth capacitor, a tenth capacitor and a twenty-seventh resistor; The fourteenth resistor, the fifteenth resistor, the sixteenth resistor and the seventeenth resistor are connected in sequence, the first end of the fourteenth resistor is connected to the U phase of the three-phase voltage output terminal of the inverter, the second end of the seventeenth resistor is respectively connected to the first end of the fifth capacitor, the first end of the sixth capacitor, the third end of the third switch diode, the first end of the twenty-third resistor, and the ninth input terminal of the operational amplifier, the second end of the sixth capacitor is connected to the second end of the twenty-second resistor and connected to the signal ground, and the first end of the twenty-second resistor is connected to the second end of the twenty-third resistor; The eighteenth resistor, the nineteenth resistor, the twentieth resistor and the twenty-first resistor are connected in sequence, the first end of the eighteenth resistor is connected to the V phase of the three-phase voltage output terminal of the inverter, the second end of the twenty-first resistor is respectively connected to the second end of the fifth capacitor, the tenth input terminal of the operational amplifier, the third end of the fourth switching diode, the first end of the twenty-fourth resistor, and the first end of the seventh capacitor, the second end of the twenty-fourth resistor is connected to the first end of the twenty-fifth resistor, the second end of the twenty-fifth resistor is respectively connected to the second end of the seventh capacitor, the eighth output terminal of the operational amplifier, and the first end of the twenty-sixth resistor, the second end of the twenty-sixth resistor is respectively connected to the first end of the eighth capacitor, the tenth input terminal of the operational amplifier, and the third end of the fourth switching diode, the first end of the twenty-fourth resistor, and the first end of the seventh capacitor. The first end of the 13th rectifier diode is connected to the second end of the 14th rectifier diode, the second end of the 8th capacitor is connected to the signal ground, the first end of the 11th rectifier diode is connected to the second end of the 12th rectifier diode and is connected to the signal ground, the second end of the 11th rectifier diode is respectively connected to the second end of the 13th rectifier diode, the first end of the 9th capacitor, the positive electrode of the 10th capacitor, the second end of the 27th resistor, and the input end of the calibration module, the first end of the 13th rectifier diode is connected to the second end of the 14th rectifier diode, the first end of the 14th rectifier diode is respectively connected to the first end of the 12th rectifier diode, the second end of the 9th capacitor, the negative electrode of the 10th capacitor, the first end of the 27th resistor, and the input end of the calibration module; The VW phase detection circuit includes: a twenty-eighth resistor, a twenty-ninth resistor, a thirtieth resistor, a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, an eleventh capacitor, a twelfth capacitor, a fifth switching diode, a sixth switching diode, a thirty-sixth resistor, a thirty-seventh resistor, a thirty-eighth resistor, a thirty-ninth resistor, a thirteenth capacitor, a fortieth resistor, a fourteenth capacitor, a fifteenth rectifier diode, a sixteenth rectifier diode, a seventeenth rectifier diode, an eighteenth rectifier diode, a fifteenth capacitor, a sixteenth capacitor, and a forty-first resistor; The twenty-eighth resistor, the twenty-ninth resistor, the thirtieth resistor, and the thirty-first resistor are connected in sequence, the first end of the twenty-eighth resistor is connected to the V phase of the three-phase voltage output end of the inverter, the second end of the thirty-first resistor is respectively connected to the first end of the eleventh capacitor, the first end of the twelfth capacitor, the third end of the fifth switch diode, the first end of the thirty-seventh resistor, and the twelfth input end of the operational amplifier, the second end of the twelfth capacitor is connected to the second end of the thirty-sixth resistor and is connected to the signal ground, and the first end of the thirty-sixth resistor is connected to the second end of the thirty-seventh resistor; The thirty-second resistor, the thirty-third resistor, the thirty-fourth resistor and the thirty-fifth resistor are connected in sequence, the first end of the thirty-second resistor is connected to the W phase of the three-phase voltage output terminal of the inverter, the second end of the thirty-fifth resistor is respectively connected to the second end of the eleventh capacitor, the third end of the sixth switch diode, the thirteenth input terminal of the operational amplifier, the first end of the thirty-eighth resistor, and the first end of the thirteenth capacitor, the second end of the thirty-eighth resistor is connected to the first end of the thirty-ninth resistor, the second end of the thirty-ninth resistor is respectively connected to the second end of the thirteenth capacitor, the fourteenth output terminal of the operational amplifier, and the first end of the fortieth resistor, and the second end of the fortieth resistor is respectively connected to the first end of the thirteenth capacitor. The first end of the fourteenth capacitor, the first end of the seventeenth rectifier diode, and the second end of the eighteenth rectifier diode are connected, the second end of the fourteenth capacitor is connected to the signal ground, the first end of the fifteenth rectifier diode is connected to the second end of the sixteenth rectifier diode and to the signal ground, the second end of the fifteenth rectifier diode is respectively connected to the second end of the seventeenth rectifier diode, the first end of the fifteenth capacitor, the positive electrode of the sixteenth capacitor, the second end of the forty-first resistor, and the input end of the calibration module, and the first end of the sixteenth rectifier diode is respectively connected to the first end of the eighteenth rectifier diode, the second end of the fifteenth capacitor, the negative electrode of the sixteenth capacitor, the first end of the forty-first resistor, and the input end of the calibration module.

5. The voltage calibration system for a frequency converter according to claim 4, characterized in that: The calibration module is a PLC controller with a built-in calibration algorithm. The PLC controller includes a voltage input terminal and a communication terminal. The voltage input terminal includes a UDC port, a UV+ port, a UV- port, a VW+ port, a VW- port and an AD port. The UDC port is connected to the second end of the thirteenth resistor, and is used to receive the bus voltage collected by the bus voltage sampling circuit and input into the PLC controller. The UV+ port is connected to the second end of the twenty-seventh resistor, and the UV- port is connected to the first end of the twenty-seventh resistor, and is used to receive the output voltage of the UV two-phase collected by the UV phase detection circuit. The VW+ port is connected to the second end of the forty-first resistor, and the VW- port is connected to the first end of the forty-first resistor, and is used to receive the output voltage of the VW two-phase collected by the VW phase detection circuit. The AD port is connected to the AO output port of the inverter and is grounded; The PLC controller communication end is connected to the inverter, and is used to read the bus voltage and control port output voltage displayed by the inverter, and compare the bus voltage collected by the acquisition module with the bus voltage displayed by the inverter according to the calibration algorithm built into the PLC controller, and calculate the difference between the two. When the difference is greater than a preset voltage threshold, the system parameters of the inverter are calibrated to obtain the bus voltage calibration result of the inverter; the control port output voltage collected by the acquisition module is compared with the control port output voltage displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the control port output voltage calibration result of the inverter.

6. The voltage calibration system for a frequency converter according to claim 2, characterized in that: The automatic test equipment also includes a power boost adjustable module; The input end of the power boost adjustable module is connected to the power supply, and the output end of the power boost adjustable module is connected to the input end of the frequency converter.

7. The voltage calibration system for a frequency converter according to claim 2, characterized in that: The automatic test equipment also includes a switching power supply module; The input end of the switching power supply module is connected to the power supply, and the output end of the switching power supply module is connected to the input end of the sampling module and the input end of the calibration module.

8. The voltage calibration system for a frequency converter according to claim 7, characterized in that: The automatic testing equipment also includes a screen display module; The input end of the screen display module is connected to the output end of the switch power supply module and the output end of the calibration module respectively.

9. The voltage calibration system for a frequency converter according to claim 8, characterized in that: When the operating frequency of the inverter is less than 15 Hz, the output voltage of the control port is a low potential voltage, and the low potential voltage value collected by the acquisition module is compared with the low potential voltage value displayed by the inverter, and the difference between the two is calculated. When the difference is greater than a preset voltage threshold, the system parameters of the inverter are calibrated to obtain a low voltage calibration result of the inverter; When the operating frequency of the inverter is greater than 40Hz, the output voltage of the control port is a high-potential voltage. The high-potential voltage value collected by the acquisition module is compared with the high-potential voltage value displayed by the inverter, and the difference between the two is calculated. When the difference is greater than the preset voltage threshold, the system parameters of the inverter are calibrated to obtain the high voltage calibration result of the inverter.

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