CN110752757A - Mining explosion-proof permanent magnet motor frequency converter and motor - Google Patents

Mining explosion-proof permanent magnet motor frequency converter and motor Download PDF

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Publication number
CN110752757A
CN110752757A CN201911055251.9A CN201911055251A CN110752757A CN 110752757 A CN110752757 A CN 110752757A CN 201911055251 A CN201911055251 A CN 201911055251A CN 110752757 A CN110752757 A CN 110752757A
Authority
CN
China
Prior art keywords
cable
frequency converter
circuit
load
permanent magnet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201911055251.9A
Other languages
Chinese (zh)
Inventor
姜钰梁
肖霆
陈雪亮
彭溪
肖烨然
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan Institute of Marine Electric Propulsion China Shipbuilding Industry Corp No 712 Institute CSIC
Original Assignee
Wuhan Institute of Marine Electric Propulsion China Shipbuilding Industry Corp No 712 Institute CSIC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan Institute of Marine Electric Propulsion China Shipbuilding Industry Corp No 712 Institute CSIC filed Critical Wuhan Institute of Marine Electric Propulsion China Shipbuilding Industry Corp No 712 Institute CSIC
Priority to CN201911055251.9A priority Critical patent/CN110752757A/en
Publication of CN110752757A publication Critical patent/CN110752757A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters

Abstract

The invention discloses a mining explosion-proof permanent magnet motor frequency converter, which comprises a three-phase rectifier arranged at an input end, an inverter connected with the three-phase rectifier through an a + cable and an a-cable, an intermediate circuit and a braking circuit, wherein the intermediate circuit is an LC filter consisting of an inductor and a capacitor, the braking circuit comprises a switching transistor, a transformer, a load, a control switch and a control connecting circuit, a primary winding of the transformer is connected with the switching transistor in series and then is respectively connected with the a + cable and the a-cable, a secondary winding of the transformer is connected with the load, the control switch controls the switching of the switching transistor through the control connecting circuit according to the voltage between the a + cable and the a-cable, each phase of the inverter is provided with two transistors, and each transistor is connected with an idle diode in parallel; the invention has the advantages of simple structure, strong adjustability, quick disassembly, high precision of welding complex workpieces and the like.

Description

Mining explosion-proof permanent magnet motor frequency converter and motor
Technical Field
The invention belongs to the technical field of explosion-proof frequency converters, and relates to an improvement on a protection circuit of an explosion-proof motor frequency converter, in particular to a mining explosion-proof permanent magnet motor frequency converter with a switch and a load brake circuit, and a motor using the frequency converter.
Background
Mining machinery such as a scraper conveyor, a belt conveyor, a lifter, a ball mill and the like are low-speed and high-torque transmission systems, and the systems generally comprise a high-power asynchronous motor, a speed reducer, a hydraulic coupler and the like at present. Due to the existence of the speed reducer and the hydraulic coupler, the transmission system has low efficiency, low power factor, large vibration noise and fussy equipment maintenance. At present, the explosion-proof permanent magnet synchronous motor is more and more widely applied to mine automation equipment. The mining explosion-proof permanent magnet motor frequency converter is an important component of a permanent magnet direct drive system, and the rotating speed and the load of a permanent magnet propulsion motor are adjusted according to a control instruction of an upper computer to provide power required by the load.
However, for a motor with high moment of inertia, the energy fed back to the frequency converter is often relatively high. In this case, the cooling effect of the motor is not good. At this time, the load cannot be arranged in the casing of the frequency converter and needs to be external. Furthermore, another advantage of the load being arranged outside the frequency converter housing is that the conversion of electrical energy into other types of energy is easier to achieve. However, the disadvantage of placing the load outside the frequency converter cabinet is also evident, i.e. the load is exposed to ambient conditions. Thus, the ambient temperature and humidity, electromechanical operating conditions may affect the load, which may result in electrical faults, such as ground faults or short circuits.
Therefore, the mining explosion-proof permanent magnet motor frequency converter is necessary to be provided with a brake circuit with a switch and a load as a protection circuit, so as to perform overvoltage protection.
Chinese patent document 201710304310.6, entitled "a converter fault protection device and converter", discloses a converter fault protection device, which specifically includes a fault detection module, a wave-sealing circuit, and an enabling unit, and can detect a fault signal and block a signal output by an IGBT driving circuit in the converter, thereby effectively protecting the operating state of the converter. The fault detection module of the fault protection device can only detect faults under voltage, over voltage and over current, and does not detect a direct current component in the earth leakage current, so that the fault protection device is not functional when the load has an earth fault.
Chinese patent document No. 201820953389.5, a "circuit for braking a frequency converter by using a switching power supply", discloses a circuit for braking a frequency converter by using a switching power supply, wherein the protection circuit includes a protection resistor and a filter capacitor, the scheme directly feeds back a bus voltage as a voltage loop, and a power chip is used to generate a PWM driving waveform, so that the frequency is fixed and adjustable. Although the current mode PWM chip can be used for braking control of the frequency converter, the current mode PWM chip cannot solve electrical faults such as ground faults or short circuits, cannot realize functions such as braking and fault protection at the same time, is not in accordance with diversified design requirements of modern circuits, and has low practical value.
Disclosure of Invention
The invention provides a mining explosion-proof permanent magnet motor frequency converter with a switch and a load braking circuit, which can prevent frequency converter faults caused by overlarge voltage.
In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problem is as follows: a mining explosion-proof permanent magnet motor frequency converter comprises a three-phase rectifier arranged at an input end, an inverter connected with the three-phase rectifier through an a + cable and an a-cable, an intermediate circuit connected between the three-phase rectifier and the inverter and a braking circuit arranged between the a + cable and the a-cable, wherein the intermediate circuit is an LC filter consisting of an inductor and a capacitor, the braking circuit comprises a switching transistor, a transformer, a load, a control switch and a control connecting circuit, a primary winding of the transformer is connected with the switching transistor in series and then respectively connected with the a + cable and the a-cable, a secondary winding of the transformer is connected with the load, the control switch controls the switching of the switching transistor through the control connecting circuit according to the voltage between the a + cable and the a-cable, each phase of the inverter is provided with two transistors, each transistor is connected with an idle diode in parallel, the inverter adjusts the output power supply voltage through controlling the transistor, and the inverter supplies power to the motor through a three-phase output U, V, W.
The load of the mining explosion-proof permanent magnet motor frequency converter is a resistor, the load can convert electric energy fed back to the frequency converter from a motor into heat energy which is dissipated, and the circuit cannot be burnt out in the mode.
The mining explosion-proof permanent magnet motor frequency converter has the advantages that the primary winding and the secondary winding of the transformer are separated in a galvanic couple mode, alternating current can be transmitted to a load with relatively low loss, direct current components are effectively far away from the load, the output voltage of the transformer is lower than the input voltage, the input end of the transformer is connected with the control switch in series, the output end of the transformer is connected with the load, a direct current barrier can be formed in the transformer, and only the alternating current can be transmitted to the output end.
According to the mining explosion-proof type permanent magnet motor frequency converter, the control switch obtains the voltage between the a + cable and the a-cable by measuring the voltage of the capacitor.
The control switch of the mining explosion-proof permanent magnet motor frequency converter is an electronic switch with control connection, and a transistor or other semiconductor components are used. Such electronic switches can achieve a relatively high switching frequency, so that the size of the transformer can be reduced. In addition, the electronic switch can be controlled according to the operation instruction.
The invention also provides a mining explosion-proof permanent magnet motor which comprises the frequency converter and a fault current protection device connected with an R, S, T three-phase input power supply, wherein the fault current protection device is connected with a three-phase rectifier through R, S, T, and the load is arranged outside the circuit of the frequency converter and inside the shell of the frequency converter.
The invention has the beneficial effects that: the control connection circuit can judge whether the frequency converter is in an overvoltage state or not in the working process, if the frequency converter is in the overvoltage state, the control switch is closed, and the three-phase rectifier is connected with the capacitor, so that voltage is limited; the load is placed outside the control circuit of the frequency converter, the damage to the frequency converter caused by overlarge voltage can be effectively reduced, and the whole circuit is simple and reliable and is easy to realize.
Drawings
Fig. 1 is a schematic diagram of the structure of the present invention.
The figures are numbered: 1-fault current protection device, 2-three-phase rectifier, 3-inductor, 4-capacitor, 5-inverter, 6-a + cable, 7-a-cable, 8-switching transistor, 9-transformer, 10-load, 11-primary winding, 12-secondary winding, 13-control switch, 14-motor, 15-frequency converter, 16-control connecting circuit, Q1-Q6-transistor, D1-D6-idle diode.
Detailed Description
The invention aims to separate the load from the control connection circuit, and can effectively reduce the damage to the frequency converter when the voltage is overlarge even if the load is placed outside the control circuit of the frequency converter, and the whole circuit is simple and reliable and is easy to realize.
The brake circuit is realized without installing a high-price full-current sensitive FI switch, a relatively low-price pulse current sensitive FI switch can be used, and all direct-current elements are arranged in the frequency converter without independent protection.
The drawings that accompany the detailed description can be briefly described as follows or can be utilized as required in the prior art description, and it is apparent that the drawings in the following description are embodiments of the invention.
The mining explosion-proof permanent magnet motor with the switch and the load brake circuit has the structural principle shown in fig. 1, and comprises the frequency converter 15 and a fault current protection device 1 connected with an R, S, T three-phase input power supply, wherein the fault current protection device 1 is connected with a three-phase rectifier 2 through R, S, T, and the load 10 is arranged outside the circuit of the frequency converter 15 and inside the shell of the frequency converter 15.
Wherein the frequency converter 15 comprises a three-phase input R, S, T connected to a three-phase power supply via the fault current protection arrangement 1, the three-phase power supply being represented by three cables L1, L2, L3; the input of the frequency converter 15 is provided with a three-phase rectifier 2 which rectifies the current from the main circuits L1, L2, L3 and supplies it to the intermediate circuit. In this embodiment the intermediate circuit comprises an LC filter consisting of an inductance 3 and a capacitance 4. The LC filter functions to balance the dc power provided by the rectifier 2, introducing the dc power to the inverter 5 through the a + cable 6 and the a-cable 7, the inverter 5 powering the motor 14 through the three phase output U, V, W.
The motor 14 of the present invention is a permanent magnet motor. Each phase of the inverter 5 has two transistors Q1-Q6, with a free diode D1-D6 connected in parallel with each transistor. Not shown in fig. 1 but known in the art, the inverter 5 is provided with a controller for adjusting the U, V, W output supply voltages of the motor 14, and the controller switches are switchable between the transistors Q1-Q6 to switch to a desired frequency.
When the motor 14 is to be stopped, all of the transistors Q1-Q6 are turned off, or the voltage or frequency is reduced for faster braking, thereby changing the direction of the current. The motor 14 now functions as a generator, feeding electrical energy back to the frequency converter 15. In this way, current passes through the spare diodes D1-D6 to the intermediate circuit, resulting in an increase in the voltage between the a + cable 6 and the a-cable 7. In order to keep the voltage increase below a predetermined maximum value and to ensure accelerated braking of the motor 14, a braking circuit is connected in the intermediate circuit between the a + cable 6 and the a-cable 7, which enables the voltage increase caused by the energy fed back from the motor to be reduced quickly and efficiently.
The brake circuit is composed of a switching transistor 8, a transformer 9, a load 10, a control switch 13, a control connection circuit 16, and the like. The transformer 9 has an input connected to a control switch 13 and an output connected to a load 10, the primary winding 11 of the transformer 9 forming an input, the secondary winding 12 of the transformer 9 forming an output, and the load 10 connected to the secondary winding 12. As shown in fig. 1, the load 10 is arranged outside the circuit of the frequency converter 15 and inside the housing of the frequency converter 15. Thus, the size and performance of the load 10 is no longer limited by the internal size and environmental conditions of the frequency converter 15. This means that the heat energy converted from the dissipation of a large amount of electrical energy in the load 10 does not affect the heat dissipation of the frequency converter 15 itself.
The primary winding 11 of the transformer 9 is connected in series with a switching transistor 8, the switching transistor 8 being controlled by a control switch 13 via a control connection 16, the control switch 13 measuring the voltage between the a + cable 6 and the a-cable 7, from which voltage the switching transistor 8 can be controlled, which voltage can be derived by measuring the voltage of the capacitor 4.
The control connection circuit 16 receives the output voltage, compares the output voltage amplification with the maximum value of the preset voltage in the control connection circuit 16, and if the output voltage amplification is larger than the maximum value of the preset voltage, that is, the frequency converter 15 is in an overvoltage state, the control connection circuit 16 connects the three-phase rectifier 2 with the capacitor 4 by using the control switch 13, so as to limit the voltage.
The switching transistor 8 controls the switching of the circuit from the a + cable 6 to the a-cable 7 by the closing or opening of the primary winding 11 of the transformer 9. By means of the duty cycle, i.e. the relation between the number of times the transistor is switched off and the sum of the number of times the transistor is switched on and off, an accurate controllable voltage drop of the intermediate circuit between the a + cable 6 and the a-cable 7 can be obtained. When the switching transistor 8 is closed, current can flow from the a + cable 6 to the a-cable 7, while current also flows through the primary winding 11 of the transformer 9 via the a-cable 7. Since the current is not constant but increases or decreases with the switching of the switching transistor over time. Thus, a current is generated in the secondary winding 12 of the transformer 9, which is a pure alternating current without a direct current component and is converted into heat in the load 10, and finally energy is dissipated from the intermediate circuit.
If the load 10 should fail to ground during normal operation, no adverse consequences occur, since only the dc voltage is available on the primary side of the transformer 9, and the dc voltage cannot be transmitted to the load 10. The same is true for the braking situation, in which the direct voltage cannot be transmitted to the load 10.
The present invention is not limited to the above-mentioned preferred embodiments, and any structural changes made under the teaching of the present invention shall fall within the protection scope of the present invention, which has the same or similar technical solutions as the present invention.

Claims (6)

1. The utility model provides a mining explosion-proof type permanent-magnet machine converter which characterized in that: the brake circuit comprises a three-phase rectifier (2) arranged at an input end, an inverter (5) connected with the three-phase rectifier (2) through an a + cable (6) and an a-cable (7), an intermediate circuit connected between the three-phase rectifier (2) and the inverter (5), and a brake circuit arranged between the a + cable (6) and the a-cable (7), wherein the intermediate circuit is an LC filter consisting of an inductor (3) and a capacitor (4), the brake circuit comprises a switching transistor (8), a transformer (9), a load (10), a control switch (13) and a control connection circuit (16), a primary winding (11) of the transformer (9) is connected with the switching transistor (8) in series and then is respectively connected with the a + cable (6) and the a-cable (7), and a secondary winding (12) of the transformer (9) is connected with the load (10), the control switch (13) controls the switching of the switching transistor (8) through a control connecting circuit (16) according to the voltage between the a + cable (6) and the a-cable (7), each phase of the inverter (5) is provided with two transistors (Q1-Q6), each transistor is connected with an idle diode (D1-D6) in parallel, and the inverter (5) adjusts the output power supply voltage through control transistors (Q1-Q6).
2. The mining explosion-proof type permanent magnet motor frequency converter according to claim 1, characterized in that the load (10) is a resistor.
3. The mining explosion-proof permanent magnet motor frequency converter according to claim 1, characterized in that the primary winding (11) and the secondary winding (12) of the transformer (9) are galvanically separated.
4. The mining explosion-proof type permanent magnet motor frequency converter according to claim 1, characterized in that the control switch (13) obtains the voltage between the a + cable (6) and the a-cable (7) by measuring the voltage of the capacitor (4).
5. The mining explosion-proof type permanent magnet motor frequency converter according to claim 1 or 2, characterized in that the control switch (13) is an electronic switch with a control connection.
6. A mining explosion-proof permanent magnet machine, characterized in that it comprises a frequency converter (15) according to claim 1 and a fault current protection device (1) connected to a three-phase input power supply, said fault current protection device (1) being connected to a three-phase rectifier (2), said load (10) being arranged outside the circuit of the frequency converter (15) and inside the housing of the frequency converter (15).
CN201911055251.9A 2019-10-31 2019-10-31 Mining explosion-proof permanent magnet motor frequency converter and motor Pending CN110752757A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201911055251.9A CN110752757A (en) 2019-10-31 2019-10-31 Mining explosion-proof permanent magnet motor frequency converter and motor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201911055251.9A CN110752757A (en) 2019-10-31 2019-10-31 Mining explosion-proof permanent magnet motor frequency converter and motor

Publications (1)

Publication Number Publication Date
CN110752757A true CN110752757A (en) 2020-02-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN201911055251.9A Pending CN110752757A (en) 2019-10-31 2019-10-31 Mining explosion-proof permanent magnet motor frequency converter and motor

Country Status (1)

Country Link
CN (1) CN110752757A (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1214156A (en) * 1996-03-22 1999-04-14 丹福斯有限公司 Frequency converter for electromotor

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1214156A (en) * 1996-03-22 1999-04-14 丹福斯有限公司 Frequency converter for electromotor

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Application publication date: 20200204