Signal measuring device, cascaded frequency converter and frequency converter system
By introducing a signal measurement device into the cascaded frequency converter and using a step-down module and a voltage acquisition module connected to the tap of the primary coil, the problems of high cost, large size and insufficient safety in the existing technology are solved, achieving high-performance signal measurement and improving the safety and reliability of the cascaded frequency converter.
Patent Information
- Application Number
- CN202520379576.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2035-03-05
AI Technical Summary
Existing signal measurement methods for cascaded frequency converters are costly, bulky, have high installation requirements, and are not safe or reliable enough, especially when using high-voltage resistors and voltage transformers to achieve voltage reduction measurement.
A signal measurement device, including a step-down module and a voltage acquisition module, is used to reduce the input voltage by connecting the tap of the primary coil and transmit the measurement results to the main control module, thus avoiding the use of high-voltage resistors and voltage transformers.
It reduces costs, size, and installation requirements, improves safety and reliability, and facilitates real-time monitoring of measurement results, enhancing ease of use.
Smart Images
Figure CN223883651U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to signal measurement technical field, especially a kind of signal measurement device, cascaded frequency converter and frequency converter system. BACKGROUND
[0002] Variable-frequency Drive (VFD) is through changing motor output voltage frequency and voltage amplitude to control motor power control equipment.Cascaded frequency converter is widely used in fan, water pump, belt conveyor, experimental power supply and other scenes. Almost every cascaded frequency converter, it needs to measure its input signal. Some measurement methods of prior art are through high-voltage resistance (megaohm, more expensive, strengthen insulation requirement high) or voltage transformer (volume is big, weight is heavy, cost is high) to realize step-down measurement, but these ways are high in cost, large in volume, high in installation requirement, easy to discharge arc, not safe and reliable enough. Therefore, a new technical scheme is needed to solve these technical problems.
[0003] The content of the background section merely represents the knowledge of the inventors, and does not necessarily form the prior art in the field. SUMMARY
[0004] In view of one or more of the problems in the prior art, the utility model provides a signal measurement device for measuring the input signal of a cascaded frequency converter, the cascaded frequency converter comprising a main control module and a phase-shift transformer, the phase-shift transformer comprising a primary coil, and the signal measurement device comprising:
[0005] a step-down module, an input end of the step-down module being connected to a tapping of the primary coil; and
[0006] a voltage acquisition module, the voltage acquisition module being connected to an output end of the step-down module and connected to the main control module.
[0007] Optionally, the primary coil comprises a three-phase primary coil, and the input ends of a plurality of the step-down modules are respectively connected to the taps of the three-phase primary coil.
[0008] Optionally, the signal measurement device further comprises:
[0009] a current acquisition module, a first sampling resistor and a second sampling resistor, the first sampling resistor and the second sampling resistor being respectively connected in series to two of the primary coils and the neutral point; the current acquisition module being connected to the first sampling resistor and the second sampling resistor and connected to the main control module.
[0010] Optionally, the signal measurement device further comprises:
[0011] The voltage acquisition module and / or the current acquisition module comprise a processing module connected to the main control module.
[0012] Optionally, the signal measurement device further comprises:
[0013] A communication module electrically isolatedly connected to an output end of the processing module and the main control module.
[0014] Optionally, the communication module comprises at least one of a fiber transceiver, an infrared transceiver, a Bluetooth module, a WiFi module, a ZigBee module, a 4G module or a 5G module.
[0015] Optionally, the signal measurement device further comprises:
[0016] A power module, an input end of the power module connected to the tap, and an output end of the power module connected to at least one of the voltage reduction module, the voltage acquisition module, the current acquisition module, the processing module or the communication module.
[0017] The utility model also provides a kind of cascade frequency converter, including the signal measurement device as described above.
[0018] The utility model also provides a kind of frequency converter system, comprising:
[0019] Cascade frequency converter, the cascade frequency converter includes phase-shift transformer, the phase-shift transformer includes primary coil, and the primary coil includes tap and neutral point;And
[0020] The signal measurement device as described above is connected to the tap of the primary coil, and the input signal of the cascade frequency converter can be measured.
[0021] The signal measurement device of the utility model, by connecting the input end of voltage reduction module with the tap of primary coil, and connecting the output end of voltage acquisition module with voltage reduction module and main control module, without high voltage resistance (megaohm, more expensive, strengthen insulation requirement high) or voltage transformer realizes voltage reduction, reduces cost, volume and installation requirement, improves safety, reliability and use convenience, while the measurement result can be communicated to main control module, so that cascade frequency converter can grasp measurement result in time. BRIEF DESCRIPTION OF DRAWINGS
[0022] The drawings are used to provide further understanding of the utility model, and constitute part of specification, and are used to explain the utility model together with the embodiments of the utility model, and do not constitute the limitation to the utility model.In the drawings:
[0023] Figure 1A schematic view of a signal measurement device according to some embodiments of the present application is shown.
[0024] Figure 2 A schematic view of a cascaded frequency converter according to some embodiments of the present application is shown.
[0025] Figure 3 A schematic view of a primary coil according to some embodiments of the present application is shown.
[0026] Figure 4 A schematic view of a signal measurement device according to some embodiments of the present application is shown.
[0027] Figure 5 A schematic view of a primary coil according to some embodiments of the present application is shown.
[0028] Figure 6 A schematic view of a signal measurement device according to some embodiments of the present application is shown.
[0029] Figure 7 A schematic view of a signal measurement device according to some embodiments of the present application is shown.
[0030] Figure 8 A partial schematic view of a signal measurement device according to some embodiments of the present application is shown.
[0031] Figure 9 A schematic view of a cascaded frequency converter according to some embodiments of the present application is shown.
[0032] Figure 10 A schematic view of a frequency converter system according to some embodiments of the present application is shown.
[0033] Reference signs:
[0034] 100: signal measurement device
[0035] 101: voltage reduction module
[0036] 102: voltage acquisition module
[0037] 103: current acquisition module
[0038] 104: processing module
[0039] 105: communication module
[0040] 106: power module
[0041] 200: cascaded frequency converter
[0042] 201: main control module
[0043] 202: primary coil
[0044] P: tap
[0045] N: neutral point
[0046] 203: iron core
[0047] 204: secondary coil
[0048] 205: power unit
[0049] 300: frequency converter system DETAILED DESCRIPTION
[0050] Hereinafter, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.
[0051] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.
[0052] In the description of the present application, it needs to be explained that, unless otherwise specifically specified and limited, the terms "mounting", "connecting", "connection", "coupling" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements; it can be electrically isolated connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0053] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature is "on", "above" and "on top of" the second feature, which includes that the first feature is directly above and obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature is "under", "below" and "underneath" the second feature, which includes that the first feature is directly below and obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.
[0054] A number of different implementations or examples are provided below to implement different structures of the present application. In order to simplify the present application, the components and settings of specific examples are described below. Of course, they are only examples and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various implementations and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.
[0055] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not intended to limit the present application.
[0056] The utility model provides a kind of signal measurement device, for measuring the input signal of cascaded frequency converter.Cascaded frequency converter includes phase-shift transformer.Phase-shift transformer includes primary coil.Primary coil includes tap and neutral point.Signal measurement device includes voltage reduction module and voltage acquisition module.The input end of voltage reduction module is connected the tap of primary coil.The input end of voltage acquisition module is connected the output end of voltage reduction module, and the output end of voltage acquisition module is connected the main control module of cascaded frequency converter.The signal measurement device of the utility model, by connecting the input end of voltage reduction module the tap of primary coil, and connecting the output end of voltage reduction module and connecting main control module by voltage acquisition module, without through high voltage resistance (megaohm, more expensive, strengthen insulation requirement high) or voltage transformer, voltage reduction is realized, reduce cost, volume and installation requirement, improve safety, reliability and use convenience, while the measurement result can be communicated to main control module, to facilitate cascaded frequency converter to grasp measurement result in time.
[0057] Figure 1 A schematic diagram of a signal measurement device 100 according to some embodiments of the present application is shown. Figure 2A schematic diagram of a cascaded frequency converter 200 according to some embodiments of the present application is shown. Figure 3 A schematic diagram of a primary coil 202 according to some embodiments of the present application is shown. Reference is made below to Figures 1 to 3 the description.
[0058] The cascaded frequency converter 200 includes a main control module 201 and a phase-shift transformer.
[0059] The main control module 201 can include components and circuitry such as control circuitry, a Central Processing Unit (CPU), a Micro Control Unit (MCU), a Digital Signal Processor (DSP), other general purpose processors, an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), a Complex Programmable Logic Device (CPLD) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, etc.
[0060] The phase-shift transformer includes a primary coil 202. The primary coil 202 can be connected to a power grid (e.g., 10kV / 50Hz, 13.8kV or even 15kV, etc.). The primary coil 202 includes a tap P and a neutral point N. The tap P includes at least one of ±10% tap, ±5% tap, ±2.5% tap and 0% tap. The phase-shift transformer further includes a core 203 and a secondary coil 204.
[0061] The cascaded frequency converter 200 can be a cascaded high-voltage frequency converter (e.g., 10kV / 50Hz, 13.8kV or even 15kV, etc.). The cascaded frequency converter 200 can include a plurality of power unit groups. Each power unit group includes a plurality of power units 205 cascaded. Exemplarily, as shown in Figure 2 a purple rectangle represents one power unit 205, one row of power units 205 constitutes one power unit group, and three rows of power units 205 constitute three power unit groups. Each power unit 205 is connected to the secondary coil 204 and the main control module 201, respectively. The three-phase output of the cascaded frequency converter 200 is connected to a motor M.
[0062] The cascaded frequency converter 200 can further comprise one or more of a Human Machine Interface (HMI), a Drive Advisor (DA), and a Programmable Logic Controller (PLC). The HMI, DA, and PLC are connected to the main control module 201, and can communicate with and share data with one or more of the main control module 201, a control unit (not shown) of the power unit 205, and the signal measurement device 100.
[0063] The signal measurement device 100 is configured to measure an input signal of the cascaded frequency converter 200. The input signal of the cascaded frequency converter 200 is a voltage and / or current signal from a power grid input to the primary coil 201. The signal measurement device 100 comprises a voltage reduction module 101 and a voltage acquisition module 102.
[0064] The input of the voltage reduction module 101 is connected to a tap P of the primary coil 202. The tap P comprises at least one of a +10% tap, a -10% tap, a +5% tap, a -5% tap, a +2.5% tap, a -2.5% tap, or a 0% tap. In other words, the tap P can be at least one of a +10% tap, a -10% tap, a +5% tap, a -5% tap, a +2.5% tap, a -2.5% tap, or a 0% tap. Assuming that the neutral point N is connected to the 0% tap, if the voltage reduction module 101 is connected to the +10% or -10% tap, the input voltage at the tap is 10% of the input voltage of the cascaded frequency converter. If the voltage reduction module 101 is connected to the +5% or -5% tap, the input voltage at the tap is 5% of the input voltage of the cascaded frequency converter. If the voltage reduction module 101 is connected to the +2.5% or -2.5% tap, the input voltage at the tap is 2.5% of the input voltage of the cascaded frequency converter. Assuming that the neutral point N is connected to the +5% or -5% tap, if the voltage reduction module 101 is connected to the 0% tap, the input voltage at the tap is 5% of the input voltage of the cascaded frequency converter. And so on. The signal measurement device of the present application measures the input voltage of the cascaded frequency converter based on the voltage at the tap, and the voltage amplitude is greatly reduced, without the need for a high-voltage resistor (mega-ohm, relatively expensive) or a voltage transformer to achieve voltage reduction, and the cost, volume, and installation requirements are reduced, and the use convenience is improved. Since the input voltage at the tap is significantly smaller than the input voltage of the cascaded frequency converter, the volume and electrical isolation gap requirement of the voltage reduction resistor (kilo-ohm, relatively inexpensive) of the voltage reduction module 101 is greatly reduced, greatly saving the device cost and circuit board area, and helping to achieve high cost performance and miniaturization.
[0065] The input end of the voltage collection module 102 is connected to the output end of the step-down module 101, and the output end of the voltage collection module 102 is connected to the main control module 201 of the cascade frequency converter 200. In some embodiments, as shown in Figure 1 The voltage collection module 102 can communicate the voltage value of the input voltage of the cascade frequency converter collected by the voltage collection module 102 to the main control module 201. In some embodiments, as shown in Figure 6 The voltage collection module 102 can include a processing module 104. The processing module 104 can calculate the effective value of the input voltage of the cascade frequency converter based on the voltage value collected by the voltage collection module 102, and communicate the voltage effective value to the main control module 201, so that the main control module 201 can monitor the input voltage of the cascade frequency converter (for example, whether normal or not), which helps to improve the reliability of the cascade frequency converter. The processing module 104 can include, for example, an operational amplifier, a filter processing circuit, a CPU, an MCU, a DSP, other general-purpose processors, an analog-to-digital converter (ADC), an ASIC, an FPGA, a CPLD, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and the like.
[0066] In some embodiments, the primary coil 202 can be a U, V, W three-phase primary coil. The number of step-down modules 101 can be multiple. The input ends of the multiple step-down modules 101 can be respectively connected to the taps P of the U, V, W three-phase primary coils 202. The number of voltage collection modules 102 can be multiple. The multiple voltage collection modules 102 are respectively connected to the output ends of the multiple step-down modules 101, and are connected to the main control module 201 of the cascade frequency converter 200. For example, as shown in Figure 3 The neutral point N is connected to the 0% tap, the input ends of the three step-down modules 101 can be respectively connected to the +5% tap P or the -5% tap P of the U, V, W three-phase primary coils 202, but are not limited to this. The three voltage collection modules 102 can be respectively connected to the output ends of the three step-down modules 101, and are connected to the main control module 201 of the cascade frequency converter 200. The multiple step-down modules 101 can be independently arranged or integrated. The multiple voltage collection modules 102 can be independently arranged or integrated.
[0067] Figure 4 A schematic diagram of a signal measurement device 100 according to some embodiments of the present application is shown. Figure 5 A schematic diagram of a primary coil 202 according to some embodiments of the present application is shown. As shown in Figure 4 And Figure 5As shown, the signal measurement device 100 comprises a current acquisition module 103. The signal measurement device 100 further comprises a first sampling resistor R1 and a second sampling resistor R2. The first sampling resistor R1 and the second sampling resistor R2 are connected in series with two phases (U, W) of the primary side coil 202 of the cascaded frequency converter 200 respectively. Figure 5 The U, W phases of the primary side coil 202 and the neutral point N are exemplarily shown. The current acquisition module 103 connects the first sampling resistor R1 and the second sampling resistor R2, and connects the main control module 201 of the cascaded frequency converter 200. The neutral point N is connected with the 0% tap. It can be understood that the neutral point N is the short-circuit position of the U, V, W three-phase primary side coil 202. The current acquisition module 103 can calculate the real-time value of the input current of the cascaded frequency converter according to the voltage across the first sampling resistor R1 and the second sampling resistor R2 (the voltage across the circuit divided by the resistance value), and communicate the real-time value of the current to the main control module 201. In some embodiments, as shown, Figure 6 The current acquisition module 103 can comprise a processing module 104. The processing module 104 can further calculate the effective value based on the real-time value of the current acquired by the current acquisition module 103, and communicate the effective value of the current to the main control module 201, so that the main control module 201 can monitor the input current of the cascaded frequency converter (for example, whether normal or not), which helps to improve the reliability of the cascaded frequency converter. It should be noted that the current acquisition module 103 and the voltage acquisition module 102 can independently set the processing module 104, or they can share one processing module 104. In actual application, it can be set according to the demand.
[0068] Figure 6 A schematic diagram of the signal measurement device 100 according to some embodiments of the present application is shown. As shown, Figure 6As shown, the voltage acquisition module 102 and / or the current acquisition module 103 also include a processing module 104. The processing module 104 is connected to the main control module 201 of the cascaded frequency converter 200. The processing module 104 may include operational amplifiers, filtering circuits, CPUs, MCUs, DSPs, other general-purpose processors, analog-to-digital converters (ADCs), ASICs, FPGAs, CPLDs, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and other components and circuits. In some embodiments, the processing module 104 can calculate at least one of active power, reactive power, or apparent power based on the voltage value acquired by the voltage acquisition module 102 and / or the current value acquired by the current acquisition module 103, and communicate this calculation to the main control module 201, facilitating the main control module 201's monitoring of the energy consumption and efficiency of the cascaded frequency converter. This allows for low-cost communication between the processing module 104 and the main control module. In some embodiments, the processing module 104 may also quickly transmit the real-time values of the acquired voltage and / or current signals to the main control module 201, so that the main control module 201 can fit and reconstruct the waveform of the input voltage and / or current.
[0069] Figure 7 A schematic diagram of a signal measuring device 100 according to some embodiments of the present invention is shown. Figure 7 As shown, the signal measurement device 100 also includes a communication module 105. The communication module 105 is electrically isolated from the output of the processing module 104 and the main control module 201. It should be understood that, for the sake of system control and personal safety, the communication between the signal measurement device and the main control module 201 must meet the requirements of safe electrical isolation. The communication module 105 can be at least one of the following isolated communication modules: fiber optic transceiver, infrared transceiver, Bluetooth module, WiFi module, ZigBee module, 4G module, or 5G module. In some embodiments, the processing module 104 can perform analog-to-digital conversion based on the analog voltage signal output by the voltage acquisition module 102 and / or the analog current signal output by the current acquisition module 103, determine the discrete values of the voltage signal and / or the discrete values of the current, and communicate the discrete voltage values and / or discrete current values to the main control module 201 at high speed through the communication module 205, so that the main control module 201 can track the phase and real-time value of the input voltage and / or current signal (or power grid) of the cascaded frequency converter 200 in real time.
[0070] In some embodiments, the signal measurement device 100 can comprise a storage module (not shown in the figure). The storage module is used to store measurement data. The storage module comprises a memory. The memory comprises a random access memory (RAM) and can also comprise a non-volatile memory. Further, the memory can comprise at least one of a phase-change random access memory (PRAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), a read-only memory (ROM), and an electrically erasable programmable read only memory (EEPROM).
[0071] Figure 8 A partial schematic diagram of a signal measurement device 100 according to some embodiments of the present application is shown. As shown in Figure 8 The signal measurement device 100 further comprises a power module 106. An input end of the power module 106 is connected to the tap P, and an output end of the power module 106 is connected to at least one of the voltage reduction module 101, the voltage acquisition module 102, the current acquisition module 103, the processing module 104, or the communication module 105. The power module 106 takes power from the tap P, and is used to supply power to at least one of the voltage reduction module 101, the voltage acquisition module 102, the current acquisition module 103, the processing module 104, or the communication module 105, so that the signal measurement device takes power from the primary side of the transformer, and does not need to take power from a 220V power supply, thereby reducing the isolation requirement (if power is taken from 220V, enhanced insulation with high voltage such as 10kV needs to be met), difficulty, and cost of power taking, and improving the safety of the product. The present application does not limit the specific implementation manner of the power module 106. For example, the power module 106 can comprise a switching power supply or a power frequency transformer, as long as it can function as a voltage reduction and voltage stabilization power supply.
[0072] The present application further provides a cascaded frequency converter. Figure 9 A schematic diagram of a cascaded frequency converter 200 according to some embodiments of the present application is shown. As shown in Figure 9 The cascaded frequency converter 200 comprises the signal measurement device 100 as described above. The cascaded frequency converter of the present application uses a small-size, high-performance-price-ratio signal measurement device to measure the input signal, thereby improving the safety, reliability, and use convenience.
[0073] The utility model also provides a frequency converter system. Figure 10 A schematic diagram of a frequency converter system 300 according to some embodiments of the utility model is shown. As shown, Figure 10 The frequency converter system 300 includes a cascade frequency converter 200 and a signal measurement device 100 as described above. The cascade frequency converter 200 includes a main control module 201 and a phase-shift transformer. The phase-shift transformer includes a primary coil 202. The primary coil 202 includes a tap P and a neutral point N. The signal measurement device 100 is connected to the tap P of the primary coil 202 and the main control module 201, and can measure the input signal of the cascade frequency converter 200 and communicate the input signal to the main control module 201. The frequency converter system of the utility model uses a small-size, high-performance-price-ratio signal measurement device 100 to measure the input signal of the cascade frequency converter 200, and improves the safety, reliability and use convenience.
[0074] It should be noted that although several modules of the signal measurement device / cascade frequency converter / frequency converter system are mentioned in the foregoing detailed description, such division is merely not mandatory. In fact, according to the embodiments of the utility model, the features and functions of two or more modules described above can be implemented in one module. Conversely, the features and functions of one module described above can be further divided into modules for specific implementation.
[0075] It should be noted that the utility model can only include Figures 1-10 any one or more features of any one or more embodiments. In other words, not all the features shown must be implemented in the signal measurement device / cascade frequency converter / frequency converter system of the utility model at the same time.
[0076] Finally, it should be noted that: the above only describes the preferred embodiments of the utility model, and does not limit the utility model, although the utility model is described in detail with reference to the foregoing embodiments, and for those skilled in the art, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the utility model should be included in the protection scope of the utility model.
Claims
1. A signal measuring device for measuring an input signal of a cascaded frequency converter, the cascaded frequency converter comprising a main control module and a phase-shift transformer, the phase-shift transformer comprising a primary winding, the primary winding comprising a tap and a neutral point, characterized in that, The signal measurement device comprises: a step-down module, an input end of the step-down module being connected to the tapping of the primary coil; and a voltage acquisition module, an input end of the voltage acquisition module being connected to an output end of the step-down module, and an output end of the voltage acquisition module being connected to the main control module.
2. The signal measuring device of claim 1, wherein, The primary coil comprises three-phase primary coils, and input ends of a plurality of step-down modules are respectively connected to the tapping of the three-phase primary coils.
3. The signal measuring device of claim 1, wherein, Further comprising: a current acquisition module, a first sampling resistor and a second sampling resistor, the first sampling resistor and the second sampling resistor being respectively connected in series to two-phase primary coils and the neutral point; the current acquisition module being connected to the first sampling resistor and the second sampling resistor, and being connected to the main control module.
4. The signal measuring device of claim 3, wherein, The voltage acquisition module and / or the current acquisition module comprise a processing module, the processing module being connected to the main control module.
5. The signal measuring device of claim 4, wherein, Further comprising: a communication module, an output end of the processing module being electrically isolated and connected to the main control module by the communication module.
6. The signal measuring device of claim 5, wherein, The communication module comprises at least one of an optical fiber transceiver, an infrared transceiver, a Bluetooth module, a WiFi module, a ZigBee module, a 4G module or a 5G module.
7. The signal measuring device of claim 5, wherein, Further comprising: a power supply module, an input end of the power supply module being connected to the tapping, and an output end of the power supply module being connected to at least one of the step-down module, the voltage acquisition module, the current acquisition module, the processing module or the communication module.
8. A cascade frequency inverter characterized by comprising: The signal measurement device comprises any one of claims 1-7.
9. A frequency converter system characterized by The signal measurement device comprises: a cascaded frequency converter, the cascaded frequency converter comprising a phase-shift transformer, the phase-shift transformer comprising a primary coil, the primary coil comprising a tapping and a neutral point; and the signal measurement device of any one of claims 1-7, the signal measurement device being connected to the tapping of the primary coil, and being capable of measuring the input signal of the cascaded frequency converter.