CN219351547U - Variable frequency power supply and grounding device characteristic tester - Google Patents
Variable frequency power supply and grounding device characteristic tester Download PDFInfo
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- CN219351547U CN219351547U CN202320291410.0U CN202320291410U CN219351547U CN 219351547 U CN219351547 U CN 219351547U CN 202320291410 U CN202320291410 U CN 202320291410U CN 219351547 U CN219351547 U CN 219351547U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The utility model provides a variable-frequency power supply and grounding device characteristic tester, wherein the variable-frequency power supply comprises a three-phase rectifying and filtering module, at least two conversion modules and a control module; the conversion module comprises a high-frequency switch conversion unit, a high-frequency transformer unit, a high-frequency rectification filter unit and an alternating current inversion unit which are connected in sequence; the input ends of the high-frequency switch conversion units in each conversion module are connected with the output ends of the three-phase rectification filter modules; the alternating current inversion units in each conversion module are cascaded, and the output end after cascading is used as the output end of the variable frequency power supply; the control module is connected with IGBT devices in each alternating current inversion unit and used for controlling the output frequency of the variable-frequency power supply. The utility model can solve the problems that the variable frequency power supply in the prior grounding device characteristic tester has large volume and affects accurate test.
Description
Technical Field
The utility model belongs to the technical field of variable frequency power supplies, and particularly relates to a variable frequency power supply and grounding device characteristic tester.
Background
And carrying out a handover test on the grounding devices of the newly-built power plant and the transformer substation, and carrying out a parameter test related to lightning protection on the operated grounding devices. Because of the power frequency interference of 50Hz in the grounding network, the large grounding network is generally injected with different-frequency current close to the power frequency for testing. The variable frequency signal is output through the pilot frequency power supply, the power frequency interference can be filtered through a filtering algorithm, the accuracy of test data is guaranteed, the test frequency point close to the power frequency is adopted, and the test data is very close to the test data adopting the power frequency.
However, the variable frequency power supply in the current grounding device characteristic tester is usually designed by a power frequency transformer, and the variable frequency power supply adopting the design has large volume and heavy weight, and is inconvenient to carry and transport. Meanwhile, when the voltage of the direct current bus is higher, the loss of a switching device in the variable frequency power supply is large under high voltage, higher electromagnetic interference is generated, and the output power supply contains higher multiple harmonics and is easy to influence the test.
Disclosure of Invention
In view of the above, the present utility model provides a variable frequency power supply and a grounding device characteristic tester, so as to solve the problems of large volume and influence on accurate testing of the variable frequency power supply in the current grounding device characteristic tester.
In a first aspect, an embodiment of the present utility model provides a variable frequency power supply, including a three-phase rectifying and filtering module, at least two conversion modules, and a control module;
the conversion module comprises a high-frequency switch conversion unit, a high-frequency transformer unit, a high-frequency rectification filter unit and an alternating current inversion unit which are connected in sequence; the input ends of the high-frequency switch conversion units in each conversion module are connected with the output ends of the three-phase rectification filter modules; the alternating current inversion units in each conversion module are cascaded, and the output end after cascading is used as the output end of the variable frequency power supply; the control module is connected with IGBT devices in each alternating current inversion unit and used for controlling the output frequency of the variable-frequency power supply.
With reference to the first aspect, in a possible implementation manner of the first aspect, the three-phase rectifying and filtering module includes a three-phase rectifying bridge and a first filtering capacitor;
three input ends of the three-phase rectifier bridge are connected with a three-phase alternating-current voltage source, and two output ends of the three-phase rectifier bridge are connected with each high-frequency switch conversion unit;
the first filter capacitor is connected between two output ends of the three-phase rectifier bridge.
With reference to the first aspect, in one possible implementation manner of the first aspect, the high-frequency switch transformation unit is a first IGBT inverter H-bridge;
two input ends of the first IGBT inversion H bridge are connected with the three-phase rectification filter module, and two output ends of the first IGBT inversion H bridge are connected to the primary side of the high-frequency transformer unit.
With reference to the first aspect, in a possible implementation manner of the first aspect, the high-frequency rectifying and filtering unit includes a diode rectifying H-bridge and a second filtering capacitor;
two input ends of the diode rectification H bridge are connected to the secondary side of the high-frequency transformer unit, and two output ends of the diode rectification H bridge are connected with the alternating current inversion unit;
the second filter capacitor is connected between two output ends of the diode rectifier H bridge.
With reference to the first aspect, in a possible implementation manner of the first aspect, the ac inversion unit includes a second IGBT inversion H-bridge and an LC filter circuit;
two input ends of the second IGBT inversion H bridge are connected with the high-frequency rectification filter unit, the second IGBT inversion H bridge in each conversion module is cascaded, the output end after the cascade connection is connected with the input end of the LC filter circuit, and the output end of the LC filter circuit is used as the output end of the variable-frequency power supply.
With reference to the first aspect, in one possible implementation manner of the first aspect, the control module is connected to the IGBT devices in each ac inversion unit through an IGBT driving circuit;
the control module is also connected with the output end of the variable frequency power supply through a voltage and current feedback circuit.
Further, the control module is also connected with a temperature monitoring module, and the temperature monitoring module is used for monitoring the temperature of the variable-frequency power supply.
Further, the control module is a DSP controller adopting a space vector pulse width modulation technology.
In a second aspect, an embodiment of the present utility model provides a grounding device characteristic tester, including the variable frequency power supply according to the first aspect, where an output frequency of the variable frequency power supply is 15-70Hz.
With reference to the second aspect, in one possible implementation manner of the second aspect, the grounding device characteristic tester further includes a parameter measurement module, where the parameter measurement module is connected to the control module, and is configured to obtain voltage and current data of the output end of the variable frequency power supply through the control module, and calculate a characteristic parameter of the grounding device to be tested.
The variable frequency power supply provided by the embodiment of the utility model has the beneficial effects that:
compared with the prior art, the variable frequency power supply provided by the embodiment of the utility model has the advantages that at least two conversion modules are arranged, namely, the alternating current inversion part adopts a multi-level design, each power device only needs to bear 1/N bus voltage (N is the number of levels), the output waveform is improved due to the increase of the levels, the switching loss is small, the power supply efficiency is improved, and meanwhile, multiple harmonic waves and electromagnetic interference are reduced; in addition, the variable frequency power supply adopts a high-frequency transformer to carry out isolation boosting, and compared with the design of the traditional power frequency transformer, the variable frequency power supply has smaller volume and lighter weight 。
Drawings
Fig. 1 is a schematic diagram of the overall structure of a variable frequency power supply according to an embodiment of the present utility model;
fig. 2 is a detailed schematic diagram of a variable frequency power supply according to an embodiment of the present utility model;
FIG. 3 is a schematic diagram of a control circuit of a DSP according to an embodiment of the present utility model;
fig. 4 is a schematic structural diagram of a grounding device characteristic tester according to an embodiment of the present utility model.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the utility model is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
Fig. 1 is a schematic diagram of the overall structure of a variable frequency power supply according to an embodiment of the present utility model.
Referring to fig. 1, the variable frequency power supply includes a three-phase rectifying and filtering module 10, at least two conversion modules 11 (two are illustrated in the drawing as an example), and a control module 12.
The conversion module 11 includes a high-frequency switching conversion unit 110, a high-frequency transformer unit 111, a high-frequency rectifying and filtering unit 112, and an ac inversion unit 113, which are connected in this order.
The input ends of the high-frequency switch conversion units 110 in each conversion module 11 are connected with the output ends of the three-phase rectification filter modules 10, the alternating current inversion units 113 in each conversion module 11 are cascaded, and the cascaded output ends are used as the output ends of the variable-frequency power supply. The control module 12 is connected to the IGBT devices in each ac inverter unit 113, and is used to control the output frequency of the variable frequency power supply.
As a possible implementation, referring to fig. 2, the three-phase rectifying and filtering module 10 includes a three-phase rectifying bridge (composed of rectifying diodes D1, D2, D3, D4, D5, D6) and a first filter capacitor C1. Three input ends of the three-phase rectifier bridge are respectively connected with A, B, C three phases of a three-phase alternating-current voltage source, and two output ends of the three-phase rectifier bridge are connected with each high-frequency switch conversion unit 110. The first filter capacitor C1 is connected between two output ends of the three-phase rectifier bridge.
In this embodiment, the three-phase rectifying and filtering module 10 is used for rectifying and filtering the three-phase 380V ac voltage into a dc voltage.
As one possible implementation, referring to fig. 2, the high frequency switching transformation unit 110 is a first IGBT inverted H-bridge (made up of IGBT devices Q1, Q2, Q3, Q4). Two input ends of the first IGBT inversion H bridge are connected with the three-phase rectification filter module 10, and two output ends of the first IGBT inversion H bridge are connected to the primary side of the high-frequency transformer unit T1 (111).
In the present embodiment, the high-frequency switching conversion unit 110 is configured to convert the rectified dc voltage into a high-frequency ac square wave voltage, the number of which corresponds to the number of ac inverter units 113 in cascade connection at the subsequent stage. The bridge type inversion structure is adopted, so that soft switching can be realized, and the loss of the power switching device is reduced.
As a possible implementation, referring to fig. 2, the high frequency rectifying and filtering unit 112 includes a diode rectifying H-bridge (composed of fast diodes D7, D8, D9, D10) and a second filter capacitor C2. Two input terminals of the diode-rectified H-bridge are connected to the secondary side of the high-frequency transformer unit T1 (111), and two output terminals of the diode-rectified H-bridge are connected to the ac inverter unit 113. The second filter capacitor C2 is connected between the two output terminals of the diode rectifier H-bridge.
In this embodiment, the high-frequency transformer unit T1 (111) is used to achieve electrical isolation and boost, and the volume and weight are smaller than those of a conventional power frequency transformer. The high-frequency rectifying and filtering unit 112 is configured to rectify the isolated high-frequency square wave voltage into a direct current voltage in accordance with the number of the ac inverter units 113 cascaded in the subsequent stage.
As one possible implementation, referring to fig. 2, the ac inverter unit 113 includes a second IGBT inverter H bridge (made up of IGBT devices Q5, Q6, Q7, Q8) and LC filter circuits (L1, C3). The two input ends of the second IGBT inversion H bridge are connected with the high-frequency rectification filter unit 112, the second IGBT inversion H bridge in each conversion module 11 is cascaded, the output end after the cascade is connected with the input end of the LC filter circuit, and the output end of the LC filter circuit is used as the output end of the variable-frequency power supply.
In this embodiment, 2 (shown in fig. 1 and fig. 2) or more second IGBT inversion H-bridges may be selected for cascading according to the maximum output voltage value of the designed power supply module, and the more second IGBT inversion H-bridges that need to be cascaded are required for higher maximum output voltage requirements, each second IGBT inversion H-bridge contains 4 power switching tubes, and the direct-current voltage is converted into an SPWM alternating voltage signal by receiving a pulse width modulation signal of the DSP controller. The alternating current inversion part adopts a multi-level design, each power device only needs to bear 1/N bus voltage (N is the number of levels), the output waveform is improved by increasing the levels, the switching loss is small, the power efficiency is improved, and meanwhile, multiple harmonics and electromagnetic interference are reduced.
As a possible implementation, the control module 12 may be connected to the IGBT devices in each ac inverter unit 113 through an IGBT driving circuit. The control module 12 may also be connected to the output of the variable frequency power supply through a voltage-current feedback circuit.
In this embodiment, referring to fig. 3, the control module 12 may be a DSP controller that employs space vector pulse width modulation techniques. The DSP controller receives the frequency, voltage and current information sent by the upper computer through the communication interface, and generates an SPWM pulse modulation wave according to the required frequency and voltage signals, and the pulse modulation signal is sent to the ac inverter unit 113 after passing through the driver. The DSP controller changes the duty ratio of the internal PWM to realize accurate control of the voltage and the current by collecting the output voltage signals and the output current signals, and meanwhile, the DSP controller changes the carrier frequency of the internal timer to reach the output frequency of the set variable-frequency power supply, and the output frequency range of the variable-frequency power supply is 15-70Hz. The DSP controller monitors the temperature signal of the variable frequency power supply at the same time, and sends out a protection signal when the internal temperature is too high, so that the variable frequency power supply stops working.
Compared with the prior art, the variable frequency power supply provided by the embodiment of the utility model has the advantages that at least two conversion modules are arranged, namely, the alternating current inversion part adopts a multi-level design, each power device only needs to bear 1/N bus voltage (N is the number of levels), the output waveform is improved due to the increase of the levels, the switching loss is small, the power supply efficiency is improved, and meanwhile, multiple harmonic waves and electromagnetic interference are reduced; in addition, the variable frequency power supply adopts the high-frequency transformer to carry out isolation boosting, and compared with the design of the traditional power frequency transformer, the variable frequency power supply has smaller volume, lighter weight and convenient carrying and transportation. And the DSP controller collects voltage and current in real time, and adjusts the width of PWM so that the output voltage and current value is stabilized at a set value, thereby ensuring the accuracy of the measurement of the parameters of the ground network.
The embodiment of the utility model provides a grounding device characteristic tester, which comprises the variable-frequency power supply, wherein the output frequency of the variable-frequency power supply is 15-70Hz.
As a possible implementation manner, referring to fig. 4, the grounding device characteristic tester further includes a parameter measurement module, where the parameter measurement module is connected to the control module, and is configured to obtain voltage and current data of the output end of the variable frequency power supply through the control module, and calculate a characteristic parameter of the grounding device to be tested.
The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the utility model.
Claims (10)
1. A variable frequency power supply, comprising: the device comprises a three-phase rectifying and filtering module, at least two conversion modules and a control module;
the conversion module comprises a high-frequency switch conversion unit, a high-frequency transformer unit, a high-frequency rectification filter unit and an alternating current inversion unit which are connected in sequence; the input ends of the high-frequency switch conversion units in each conversion module are connected with the output ends of the three-phase rectifying and filtering modules; the alternating current inversion units in each conversion module are cascaded, and the output end after cascading is used as the output end of the variable frequency power supply; and the control module is connected with IGBT devices in each alternating current inversion unit and is used for controlling the output frequency of the variable-frequency power supply.
2. The variable frequency power supply of claim 1, wherein the three-phase rectifying and filtering module comprises a three-phase rectifying bridge and a first filtering capacitor;
three input ends of the three-phase rectifier bridge are connected with a three-phase alternating-current voltage source, and two output ends of the three-phase rectifier bridge are connected with the high-frequency switch conversion units;
the first filter capacitor is connected between two output ends of the three-phase rectifier bridge.
3. The variable frequency power supply of claim 1, wherein the high frequency switching unit is a first IGBT inverter H-bridge;
two input ends of the first IGBT inversion H bridge are connected with the three-phase rectification filter module, and two output ends of the first IGBT inversion H bridge are connected to the primary side of the high-frequency transformer unit.
4. The variable frequency power supply according to claim 1, wherein the high frequency rectifying and filtering unit comprises a diode rectifying H-bridge and a second filter capacitor;
two input ends of the diode rectification H bridge are connected to the secondary side of the high-frequency transformer unit, and two output ends of the diode rectification H bridge are connected with the alternating current inversion unit;
the second filter capacitor is connected between two output ends of the diode rectifier H bridge.
5. The variable frequency power supply of claim 1, wherein the ac inversion unit comprises a second IGBT inversion H-bridge and an LC filter circuit;
two input ends of the second IGBT inversion H bridge are connected with the high-frequency rectification filter unit, the second IGBT inversion H bridge in each conversion module is cascaded, the output end after the cascade connection is connected with the input end of the LC filter circuit, and the output end of the LC filter circuit is used as the output end of the variable-frequency power supply.
6. The variable frequency power supply according to any one of claims 1 to 5, wherein the control module is connected to IGBT devices in each ac inversion unit through an IGBT drive circuit;
the control module is also connected with the output end of the variable frequency power supply through a voltage and current feedback circuit.
7. The variable frequency power supply of claim 6, wherein the control module is further coupled to a temperature monitoring module for monitoring the temperature of the variable frequency power supply.
8. The variable frequency power supply of claim 6, wherein the control module is a DSP controller employing space vector pulse width modulation techniques.
9. A grounding device characteristic tester, characterized by comprising a variable frequency power supply according to any one of claims 1-8, the output frequency of which is 15-70Hz.
10. The grounding device characteristic tester according to claim 9, further comprising a parameter measurement module, wherein the parameter measurement module is connected with the control module, and is configured to obtain voltage and current data of an output end of the variable frequency power supply through the control module, and calculate a characteristic parameter of the grounding device to be tested.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320291410.0U CN219351547U (en) | 2023-02-23 | 2023-02-23 | Variable frequency power supply and grounding device characteristic tester |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320291410.0U CN219351547U (en) | 2023-02-23 | 2023-02-23 | Variable frequency power supply and grounding device characteristic tester |
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| CN219351547U true CN219351547U (en) | 2023-07-14 |
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