CN112367002A - Power transformation frequency converter - Google Patents
Power transformation frequency converter Download PDFInfo
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- CN112367002A CN112367002A CN202011407153.XA CN202011407153A CN112367002A CN 112367002 A CN112367002 A CN 112367002A CN 202011407153 A CN202011407153 A CN 202011407153A CN 112367002 A CN112367002 A CN 112367002A
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- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
- H02B1/20—Bus-bar or other wiring layouts, e.g. in cubicles, in switchyards
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
- H02B1/26—Casings; Parts thereof or accessories therefor
- H02B1/30—Cabinet-type casings; Parts thereof or accessories therefor
- H02B1/308—Mounting of cabinets together
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
- H02B1/56—Cooling; Ventilation
- H02B1/565—Cooling; Ventilation for cabinets
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- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/003—Constructional details, e.g. physical layout, assembly, wiring or busbar connections
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- 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
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- 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
- H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
- H02P5/74—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors controlling two or more ac dynamo-electric motors
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/14—Mounting supporting structure in casing or on frame or rack
- H05K7/1422—Printed circuit boards receptacles, e.g. stacked structures, electronic circuit modules or box like frames
- H05K7/1427—Housings
- H05K7/1432—Housings specially adapted for power drive units or power converters
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/20909—Forced ventilation, e.g. on heat dissipaters coupled to components
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/20927—Liquid coolant without phase change
Abstract
The invention discloses a power transformation frequency converter. This transformer converter includes: the incoming line room comprises a plurality of wiring chambers and is used for butting cables so as to receive and output a plurality of paths of three-phase alternating currents with different voltage values; a rectifying unit for converting the three-phase alternating current output from the inlet room into direct current; the direct current output by the rectifying unit is converted into alternating current with different frequency from the three-phase alternating current received by the wire inlet chamber, and the control unit is used for controlling the inverting unit to output the alternating current with different frequency. The power transformation frequency converter can meet the use requirement of double power supplies by arranging two sets of cable input systems with different voltages, thereby expanding the application range of the power transformation frequency converter. In addition, the power transformation frequency converter also adopts an integrated skid-mounted structure, thereby facilitating the installation, the movement and the maintenance of equipment.
Description
Technical Field
The present invention relates generally to the field of frequency conversion applications. More particularly, the present invention relates to a variable frequency converter.
Background
In the field of oil and natural gas exploitation, equipment such as an oil or shale gas field fracturing pump or a water injection pump is often used, and when a motor drags the fracturing pump or the water injection pump, problems related to starting, speed regulation, braking and the like are inevitably encountered. For example, for the speed regulation of the motor, the rotation speed of the motor is required to be manually changed according to the production requirement under a certain load, so that a fracturing pump or a water injection pump driven by the motor can work more efficiently. The quality of the speed regulation performance of the motor usually affects the production efficiency and the product quality. At present, the speed regulation of the motor generally comprises methods of pole-changing speed regulation, frequency-changing speed regulation, voltage-changing speed regulation, rotor circuit series resistance speed regulation and the like. Among them, the frequency-variable speed regulation is widely adopted because of its advantages of flexible speed regulation direction, good smoothness and stability, wide speed regulation range, etc.
At present, the input voltage of a frequency converter for carrying out frequency conversion and speed regulation on a motor generally has various voltage grades such as 10KV or 600V. However, the frequency converter on the market currently has only a power supply input with a single voltage class, so that the application of power supplies with multiple voltage classes cannot be satisfied. Therefore, the existing frequency converter limits the application range and the scene due to the single input power supply. Secondly, the existing power transformation frequency converter has more parts and is dispersedly arranged, so that the whole volume and weight are larger, the installation is complex, the movement is difficult, and the maintenance is difficult. In addition, in the operation process of the power transformation frequency converter, a power device generates heat seriously, and the prior art is not ideal for heat dissipation and temperature reduction, so the operation performance of the power transformation frequency converter is seriously influenced.
Disclosure of Invention
To address one or more of the above-identified problems in the background, the present invention provides a variable frequency converter for driving a motor. The power transformation frequency converter controls an inversion unit of the power transformation frequency converter through a control unit, and then three-phase alternating current is subjected to frequency conversion and is output to a motor, so that the rotating speed of the motor is changed, and equipment such as an oil or shale gas field fracturing pump or a water injection pump is dragged to operate. Meanwhile, the power transformation frequency converter is provided with a 10KV and 600V dual-input three-phase power interface, and each path of input is respectively provided with a power distribution cabinet, so that the power transformation frequency converter can adapt to more application scenes. In addition, the power transformation frequency converter is provided with a special cooling system, wherein the air-water cooling system is adopted for heat dissipation of the inversion unit and the rectification unit, so that the heat dissipation and cooling effects are more obvious, and the performance of the power transformation frequency converter is enhanced.
The invention discloses a power transformation frequency converter. The power transformation frequency converter comprises an incoming line chamber, a plurality of connecting chambers and a plurality of control circuits, wherein the incoming line chamber comprises a plurality of connecting chambers and is used for connecting cables in a butt joint mode so as to receive and output multi-path three-phase alternating currents with different voltage values; a rectifying unit for converting the three-phase alternating current output from the inlet room into direct current; the inverter unit is used for converting the direct current output by the rectifying unit into alternating current with different frequency from the three-phase alternating current received by the wire inlet chamber; and the control unit is used for controlling the inversion unit to output the alternating current with different frequencies.
In one embodiment, the wiring chambers of the incoming line room are two and the voltage of the three-phase alternating current it receives is 10KV or 600V.
In another embodiment, the power conversion converter further comprises a power conversion unit. The three-phase alternating current transformer is used for converting the voltage value of the three-phase alternating current output by the wire inlet chamber.
In yet another embodiment, the power transformation unit comprises a transformer. The primary side winding of the transformer is of a double-winding structure so as to be connected with the 10KV three-phase alternating current and the 600V three-phase alternating current respectively, and the secondary side winding of the transformer is of a single-winding structure.
In one embodiment, the incoming line room further comprises a power distribution cabinet for controlling and protecting the plurality of three-phase alternating currents of different voltage values.
In another embodiment, the variable frequency converter further comprises: the first heat dissipation system is positioned at the top of the power transformation unit and used for dissipating heat of the power transformation unit; and the second heat dissipation system is positioned at the tops of the rectifying unit and the inversion unit and used for dissipating heat of the rectifying unit and the inversion unit.
In yet another embodiment, the variable frequency converter further comprises a dc link. The direct current rectifying unit comprises a direct current bus and an energy storage capacitor, and is used for filtering, buffering and storing the direct current output by the rectifying unit.
In one embodiment, the power conversion converter further comprises: the display cabinet is used as a human-computer interface of the power transformation frequency converter and used for controlling the power transformation frequency converter; and the outgoing line cabinet is connected with the inversion unit and is used for outputting the alternating current output by the inversion unit.
In another embodiment, the power conversion converter further comprises: a first housing accommodating the display cabinet and the wire inlet chamber therein; a second case that is connected to the first case and accommodates the power conversion unit and the first heat dissipation system therein; a third case connected to the second case and accommodating the rectifying unit, the inverter unit, and the second heat dissipation system therein; and a fourth housing connected to the third housing and accommodating the outlet cabinet therein.
In yet another embodiment, the power conversion converter further comprises a base, wherein the first housing, the second housing, the third housing and the fourth housing are pryed on the base.
The power transformation frequency converter has strong functions, can monitor the operation parameters of the power transformation frequency converter in real time by configuring the display cabinet, and can send out manual control instructions to the power transformation frequency converter as a man-machine interface according to the operation state of the power transformation frequency converter. In addition, the transformation frequency converter of the invention also skid-mounts the first shell, the second shell, the third shell and the fourth shell for accommodating all parts and equipment on a base, thereby conveniently mounting all parts and equipment of the transformation frequency converter and conveniently carrying the transformation frequency converter as a whole. Meanwhile, due to the modular design, the equipment is convenient to repair and maintain.
Drawings
The above-described features of the present invention will be better understood and its numerous objects, features, and advantages will be apparent to those skilled in the art by reading the following detailed description with reference to the accompanying drawings. The drawings in the following description are only some embodiments of the invention and other drawings may be derived by those skilled in the art without inventive effort, wherein:
fig. 1 is a functional block diagram showing the components of a power conversion converter according to an embodiment of the present invention;
fig. 2 is a front view illustrating a power transformation frequency converter according to an embodiment of the present invention;
fig. 3 is a top view illustrating a variable frequency converter according to an embodiment of the present invention;
fig. 4 is a structural view illustrating an inversion unit of the power transformation inverter according to an embodiment of the present invention;
fig. 5 is a main circuit topology diagram illustrating a power conversion converter according to an embodiment of the present invention;
fig. 6 is a circuit schematic diagram illustrating a rectifying unit of the variable frequency converter according to an embodiment of the present invention; and
fig. 7 is a circuit schematic diagram illustrating an inverter unit of the variable frequency converter according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a functional block diagram showing the components of a power conversion converter 100 according to an embodiment of the present invention. To facilitate an understanding of the working principle of the invention, a load is also depicted in fig. 1. The load may be, for example, an electric motor that may be used to power equipment such as an oil or shale gas in-situ fracturing pump or water injection pump that is often used in oil and gas operations.
As shown in fig. 1, the power transformation inverter 100 of the present invention may include an incoming line room 110, a rectification unit 120, an inversion unit 130, and a control unit 140. Specifically, the incoming line room may further include a plurality of wiring chambers, such as the wiring chambers 1101 and 1102 in fig. 1, for interfacing cables from the outside and cables inside the power transformation frequency converter, so as to receive and output two paths of three-phase alternating currents with different voltage values. It is understood that although only two wiring chambers are depicted in fig. 1, the variable frequency converter of the present invention may be configured with more wiring chambers according to different application scenarios so as to receive and output a plurality of three-phase alternating currents with different voltage values.
Furthermore, the input voltage of the conventional power transformation frequency converter generally has two grades of 10KV or 600V, so that the two wiring chambers of the wire inlet chamber of the power transformation frequency converter can be respectively used for receiving 10KV three-phase alternating current or 600V three-phase alternating current. The design of the double-input power supply solves the problem that the conventional power transformation frequency converter can only work in a power supply with one voltage class, thereby expanding the application range and the use scene of the power transformation frequency converter. Through the design, the invention actually provides the skid-mounted power transformation frequency converter with double power input.
In one embodiment, the rectifying unit may be a rectifying circuit composed of a plurality of rectifying diodes, and is used for converting three-phase alternating current output by the incoming line room into direct current. In another embodiment, the inverter unit may be an inverter circuit composed of a plurality of IGBT modules, and configured to convert the dc power output by the rectifier unit into ac power having a different frequency from the three-phase ac power received by the incoming line room.
In yet another embodiment, the control unit may be comprised of a chip or system with processing capabilities for analysis, determination, and calculation, which may include, for example, a DSP ("digital signal processor") module, a PLC ("programmable logic device") module, and an information collection module. Wherein the DSP module is configured to control on and off of a switching element (IGBT module) of the inverter unit so as to enable the inverter unit to output alternating currents of different frequencies. The PLC module may be configured to control on/off of a plurality of switches or other logic control devices in the power conversion converter, for example, it may be configured to control a logic timing of a pre-charging circuit that pre-charges a transformer, or may also be configured to control a logic timing of a pre-charging circuit that pre-charges an energy storage capacitor in a dc loop. The information acquisition module is used for acquiring data such as voltage, current and frequency output by the inversion unit and feeding the data back to the DSP module so as to control the stability of parameters of alternating current output by the inversion unit. In addition, the control unit can also be used for controlling data communication with an upper computer.
Fig. 2 is a front view illustrating a variable frequency converter 200 according to an embodiment of the present invention. Fig. 3 is a top view illustrating a variable frequency converter 200 according to an embodiment of the present invention. The structure and principle of the variable frequency converter of the present invention will be described in detail with reference to fig. 2 and 3.
As shown in fig. 2 and 3, the power conversion inverter 200 of the present invention may include a first case 201, a second case 202, a third case 203, a fourth case 204, and a base 205. The first shell, the second shell, the third shell and the fourth shell can be sequentially prized on the base. Specifically, the base may be provided with a slideway, and the first, second, third, and fourth housings may be slid onto the base through the slideway and mounted, so that the power transformation frequency converter of the present invention may be realized as an integrated skid-mounted structure.
The power transformation frequency converter has a compact overall equipment structure through the skid-mounted structure and combined with a modularized design, and reduces the occupied area and space compared with the arrangement of the traditional dispersion equipment. Meanwhile, the lifting device is integrated, so that the lifting device can be lifted by a crane at one time, and the equipment is convenient to carry and move. In addition, the production and the assembly of the transformation frequency converter with the skid-mounted structure can be completed in a factory. Therefore, the field installation workload is less, and the transformer frequency converter can work only by completing the connection of the interface pipeline and external electricity, so that the transformer frequency converter is convenient and quick to install.
In one embodiment, an incoming line room and a display cabinet 301 may be housed within the first housing. Further, the incoming line room may comprise a 10KV distribution cabinet 206 and a 600V distribution cabinet 207 for controlling the on-off of 10KV three-phase alternating current and 600V three-phase alternating current, respectively. Meanwhile, the three-phase alternating current protection circuit can be used for performing overvoltage, overcurrent, short circuit and other circuit protection on the three-phase alternating current. Specifically, the 10KV power distribution cabinet and the 600V power distribution cabinet may each include a transformer therein, which is used for collecting a voltage or a current value of an input three-phase alternating current and sending the collected voltage or current value to the control unit. Then the control unit carries out analysis, judgment and other processing, and conducts or breaks the circuit according to the processing result, thereby carrying out overvoltage or overcurrent protection and other protection on the three-phase alternating current.
In another embodiment, the display cabinet may serve as a human-machine interface for the power converter for controlling the power converter. Specifically, on the one hand, the display cabinet can include output devices such as a display screen and a loudspeaker, so that workers can observe and monitor the operation state of the power transformation frequency converter conveniently, and when the power transformation frequency converter fails to operate, the loudspeaker can send out alarm information such as sound and light. On the other hand, the display cabinet can further comprise input equipment such as a mouse, a keyboard or a touch screen, so that a worker can conveniently send control instructions such as changing operation parameters (for example, changing output frequency) according to the monitored operation state of the power transformation frequency converter. The command is transmitted to the control unit of the power transformation frequency converter, and finally the command is processed by the control unit and controls and changes the operation parameters of the power transformation frequency converter.
In yet another embodiment, a reactor and a contactor may be further accommodated in the first case. The reactor may be, for example, a circuit composed of an inductance element, and is configured to perform processing such as voltage stabilization, current limitation, and interference suppression on an externally input alternating current, and output the alternating current to the rectifying unit. The contactor may be located between the reactor and an externally input ac power and is used to turn on or off the power supply of the variable frequency converter. Specifically, after the contactor coil circular telegram, coil current can produce magnetic field, and this magnetic field makes the iron core produce electromagnetic attraction and then attracts the iron core to drive the contact action of contactor, thereby make the disconnection of normally closed contact, and the linkage normally open contact is closed, so that supply power to the transformer converter. When the coil is powered off, the electromagnetic attraction disappears, the armature is released under the action of the release spring, so that the contact is restored, the normally open contact is opened, and the normally closed contact is linked to be closed, so that the power supply of the power transformation frequency converter is disconnected.
As shown in fig. 3, a first external power source interface 302 and a second external power source interface 303, which are connected to the wiring chamber 1101 and the wiring chamber 1102 and are used for introducing externally input 10KV three-phase alternating current and 600V three-phase alternating current into the power transformation inverter of the present invention, may be further disposed on the top of the first housing. Further, according to different application scenarios, a plurality of external power interfaces can be arranged on the top of the first housing, so that a plurality of power supplies with different voltage values can be introduced into the power transformation frequency converter. The power transformation frequency converter of the invention separately designs the wiring chambers of two power supply grades and is provided with the external power supply interfaces of two different voltage grades, thereby avoiding the safety risk caused by the wrong wiring of the power supply.
In one embodiment, the second housing is coupled to the first housing and may house the power transformation unit 208 and the first heat dissipation system 209 therein. Further, the power transformation unit may include a transformer. The primary side winding of the transformer can be in a double winding structure so as to be respectively connected with the 10KV three-phase alternating current and the 600V three-phase alternating current, and the secondary side winding of the transformer can be in a single winding structure. In an application scenario, the transformer is used for converting externally input 10KV or 600V three-phase alternating current into 2650KVA alternating current, so that each path of voltage level power supply can meet the power output requirement of the whole machine respectively. It is understood that the voltage values of 10KV or 600V are merely exemplary and not limiting, and those skilled in the art can also contemplate using three-phase ac power with other voltage values in light of the teachings of the present invention.
In particular, the transformer may include a core (or magnetic core) and a coil. Further, the coil may include two or more windings, wherein the winding connected to the grid is a primary coil (primary winding), and the winding connected to the input terminal of the rectifying unit is a secondary coil (secondary winding). The transformer may transform alternating voltage, current and impedance. Generally, the voltage of the three-phase alternating current supplied by the power grid is not suitable for the use of equipment such as motors. It is required to be transformed by a transformer in order to output a proper voltage to the rectifying unit. Meanwhile, the transformer can also realize matching between alternating current input voltage and direct current voltage output by the rectifying unit and high-voltage electric isolation between a high-voltage power grid and the rectifying unit of the frequency converter.
In another embodiment, the first heat dissipation system may be located at an upper portion of the transformer. The first fan may be a device that increases gas pressure and discharges gas by means of input mechanical energy, and is used to cool the transformer. Further, the first fan may include a scroll, a collector, and an impeller, and operate eccentrically by means of a rotor offset in a cylinder, so that a volume between blades in a rotor groove is changed, thereby sucking, compressing, and discharging air.
In particular, the collector may direct the gas towards the impeller and its geometry determines the gas flow conditions at the inlet of the impeller. The impeller is the most important part of the centrifugal fan, generally comprises four parts, namely a wheel cover, a wheel disc, blades and a shaft disc, and the connection mode of the structures is mainly welding and riveting. The impeller is responsible for the energy transfer process described by the euler equation, and the flow condition of the gas inside the impeller is influenced by the rotation of the impeller and the curvature of the surface, and is accompanied by phenomena of flow separation, backflow and secondary flow, so that the gas flow inside the impeller becomes very complicated. The volute of the fan is mainly used for collecting the gas coming out of the impeller, converting the kinetic energy of the gas into the static pressure energy of the gas by reducing the speed of the gas moderately and guiding the gas to flow out of the outlet of the volute.
In one embodiment, the third casing of the power transformation inverter of the present invention is connected to the second casing, and may accommodate therein the rectifying unit 210, the inverting unit 211, and the second heat dissipating system 212. Specifically, the rectifying unit may be a rectifying circuit composed of a plurality of rectifying diodes for converting three-phase alternating current output from the inlet room into direct current. The inverter unit can be an inverter circuit composed of a plurality of IGBT modules and used for converting direct current output by the rectifying unit into alternating current with different frequency from the three-phase alternating current received by the wire inlet chamber. Further, the power elements (such as the rectifier diode and the IGBT module) of the rectifier unit and the inverter unit may be respectively disposed on the first heat sink and the second heat sink, so as to perform heat dissipation and temperature reduction on the power elements.
When the rectifying unit and the inverting unit are in operation, the power elements of the rectifying unit and the inverting unit can generate a large amount of heat, and the operation performance of the rectifying unit and the inverting unit is seriously influenced. Therefore, the second heat dissipation system is used for dissipating heat and cooling the rectification unit and the inversion unit. Further, the second heat dissipation system may be an air-water cooling system, which may include a second fan 304 located at the top of the third housing, and may further include a water channel disposed inside the first and second heat dissipation plates and a water pipe 305 connecting the first and second heat dissipation plates. When the second heat dissipation system works, on one hand, cold water circularly flows through the water channel, so that heat generated by power elements of the rectification unit and the inversion unit is taken away. On the other hand, cold air is blown to the first and second heat dissipation plates through a second fan so as to further dissipate heat of the rectifying unit and the inverting unit.
Specifically, water channels may be respectively disposed inside the first heat dissipation plate and the second heat dissipation plate by digging, a plurality of water seats may be further disposed at both ends of the water channels, the water seats may be connected by water pipes 305, and the water channels, the water seats, and the water pipes are matched with each other to form water flow paths penetrating through the first heat dissipation plate and the second heat dissipation plate. In one application scenario, the water channel disposed inside the first heat dissipation plate and the second heat dissipation plate may have a winding shape, and the IGBT module and the rectifier diode are disposed outside the water channel. In the working process of the second heat dissipation system, cold water is injected into the water inlet of the first heat dissipation plate, flows in the circuitous water channel and finally flows out of the water outlet of the second heat dissipation plate, so that the heat dissipation and cooling of the heating power elements of the rectification unit and the inversion unit are realized.
In one embodiment, the fourth casing of the power transformation frequency converter of the present invention is connected to the third casing, and can accommodate therein the outlet cabinet 213 and the wire spool 214. The fourth shell is an output part of the power transformation frequency converter, and the outgoing line cabinet is connected with an output end of the inversion unit and used for outputting the alternating current output by the inversion unit to the motor. Preferably, the outlet cabinet can lead out a plurality of cables so as to supply power to a plurality of motors. The wire spool is used for accommodating multi-path cables led out from the wire outlet cabinet, so that when the power transformation frequency converter does not need an external load or is transported, moved and maintained, the multi-path cables are coiled and accommodated.
Fig. 4 is a structural view illustrating an inversion unit 400 of a power transformation inverter according to an embodiment of the present invention. Fig. 4 is a cross-sectional view of fig. 2, which is shown in the directions indicated by arrows a and a'.
As shown in fig. 4, the inverter unit of the power transformation inverter of the present invention may include a first inverter unit 401 and a second inverter unit 402. The first inverter unit and the second inverter unit may be bridge circuits composed of IGBT modules. The IGBT module may be a modular semiconductor product in which an insulated gate bipolar transistor chip (abbreviated as "IGBT") and a freewheeling diode chip ("FWD") are bridge-packaged by a specific circuit. The first inversion unit and the second inversion unit have the same function and are used for converting direct current output by the rectification unit into alternating current with different frequency from the three-phase alternating current received by the wire inlet chamber. Furthermore, the direct current output by the rectifying unit is processed by the first inverter unit and the second inverter unit, and respectively outputs a three-phase alternating current to simultaneously output to the two motors, so that the two motors are driven to operate simultaneously.
In one embodiment, a filter capacitor 403 may also be included in FIG. 4. The direct current filter is positioned between the rectifying unit and the inverting unit and is used for filtering direct current output by the rectifying unit so as to filter alternating current components in the direct current. In addition, a filter capacitor may also be used to buffer and store the direct current. In a specific embodiment, the filter capacitor of the present invention may be encapsulated by epoxy resin and encapsulated without a housing, so as to reduce the volume of the filter capacitor, increase the withstand voltage and creepage distance of the polar shell, and increase the electrical gap between the capacitors of the filter capacitor or between the filter capacitor and other components. Furthermore, the top end of the filter capacitor can be packaged with the metal fixing lug, so that the filter capacitor is effectively and firmly fixed. In addition, the filter capacitor can be connected with a circuit board where the IGBT module is located in a plugging mode, so that the filter capacitor is convenient to install and maintain.
Fig. 5 is a main circuit 500 topology diagram illustrating a variable frequency converter according to an embodiment of the present invention.
As shown in fig. 5, the main circuit 500 of the power transformation inverter of the present invention may include a pre-magnetizing circuit 501, a transformer circuit 502, a rectifying circuit 503, and an inverter circuit 504. Specifically, the precharge circuit may be composed of main switches QS1, MCB1, and a bypass switch KM1 and a bypass resistor R as shown in fig. 5. Specifically, the transformer circuit may be a circuit composed of a transformer T1, which may include a primary winding, a secondary winding, and an iron core, and is used to convert the voltage value of the three-phase alternating current output from the inlet room. Further, the primary winding of the transformer T1 has a double winding structure to connect the 10KV three-phase alternating current and the 600V three-phase alternating current, respectively, and the secondary winding has a single winding structure to output the converted alternating current to the rectifier circuit.
When a large-capacity transformer is connected to a power grid, if the instantaneous voltage of a primary side winding of the transformer is exactly the zero crossing point, the alternating current magnetic flux generated in an iron core of the transformer is the maximum at the moment because the magnetic flux phase in the iron core lags behind the voltage phase by 90 degrees. However, due to the characteristics of the core, the magnetic flux cannot be abruptly changed, so that a non-periodic magnetic flux having an opposite direction and gradually decreasing amplitude with time is generated in the core to cancel the maximum magnetic flux. After half a period, the non-periodic magnetic flux has the same direction as the alternating magnetic flux, and the non-periodic magnetic flux and the alternating magnetic flux are superposed to ensure that the magnetic flux in the iron core reaches the maximum value. The maximum magnetic flux induces an excitation inrush current 7-10 times higher than the rated current of the transformer. The excitation inrush current can generate larger impact on a power grid, and can cause the instantaneous drop of the voltage of the power grid or the tripping of a high-voltage switch; it is also possible to damage the insulation of the transformer, resulting in deformation of the transformer windings and malfunction of the transformer protection device.
Based on the principle, the pre-charging circuit limits the amplitude of the inrush current by serially connecting the resistor R in the closing loop, so that the impact and damage of the excitation inrush current to a power grid and a transformer are reduced. When the power transformation frequency converter is powered on, the PLC module of the control unit controls the main switch QS1 and the bypass switch KM1 to be closed, so that the transformer T1 is pre-charged. When the pre-magnetizing process is finished, the PLC module controls the bypass switch KM1 to be opened, and simultaneously closes the main switch MCB1, so that the external power grid starts to input three-phase alternating current with 10KV voltage or 600V voltage to the transformer T1. In one embodiment, the pre-charging circuit may further include a transformer T2 for converting the input three-phase ac power of 10KV or 600V into 380V or 220V for powering low-voltage devices, such as daily lighting, monitoring devices, emergency devices, and the like.
In another embodiment, the main circuit of the variable frequency converter of the present invention may further comprise a pre-charge circuit and a dc loop. In particular, the dc loop may include a circuit composed of a dc bus and a storage capacitor, wherein the storage capacitor may be, for example, a filter capacitor 403 shown in fig. 4. And the direct current loop is used for filtering, buffering and storing energy for the direct current output by the rectifying unit. Further, the DC bus may be composed of a DC + terminal and a DC-terminal, the energy storage capacitor may be an electrolytic capacitor, and it may include a plurality of capacitors. It can be understood that the energy storage capacitor in the dc circuit may also be replaced with other energy storage components such as an energy storage inductor according to different application scenarios, and the number of the energy storage capacitors may be multiple.
In yet another embodiment, the pre-charging circuit may be disposed at an input terminal of the rectifying unit and used for pre-charging an energy storage capacitor in the dc loop by the ac power output from the transformer T1. When the variable frequency converter is powered on, the charging moment of the energy storage capacitor in the direct current loop is equivalent to a short circuit state before the voltage is not built. In this case, since the dc voltage output from the rectifying unit is extremely high, the charging current is very large, and further, the rectifying diode, the energy storage capacitor on the dc bus, and other inverter components may be damaged. For this reason, in order to limit the charging current from being too large, it is necessary to precharge the energy storage capacitor in the dc circuit.
After the pre-charging process of the energy storage capacitor is completed, the rectifying unit can output direct current to the inverter unit through a direct current loop. Because the motor driven by the variable frequency converter belongs to inductive load, the power factor of the motor is not 1 no matter what running state the motor is in. Therefore, there is always a reactive power exchange between the dc loop and the motor, which requires an energy storage element in the dc loop for buffering, so that the dc voltage output by the rectifying unit is always kept stable. Based on the principle, the direct current loop is used for receiving and storing direct current transmitted by the rectifying unit, and processing interference suppression and the like on the direct current.
In one embodiment, the inverter circuit may be composed of a plurality of inverter bridges, and is configured to convert the dc power processed by the dc loop into an ac power having a frequency different from that of an externally input ac power, and output the ac power to the motor. Further, the inverter bridge may be configured by a plurality of IGBT modules. The IGBT module may be a modular semiconductor product in which an insulated gate bipolar transistor chip (abbreviated as "IGBT") and a freewheeling diode chip ("FWD") are bridge-packaged by a specific circuit.
Specifically, in the operation process of the inverter circuit, the inverter bridge plays a key role in the process of converting direct current into three-phase alternating current. The on-off time of the power switch elements of the upper bridge and the lower bridge is controlled by pulse width modulation signals generated by the control unit, so that three-phase alternating current with 120 degrees of phase difference is obtained at three output ends of the inverter bridge, and the three-phase alternating current is output to the motor. In one embodiment, the power switching elements may be, for example, "IGBT" modules, which have the advantage of high input impedance and low turn-on voltage.
Fig. 6 is a circuit schematic diagram illustrating a rectifying unit 600 of the variable frequency converter according to an embodiment of the present invention. It will be appreciated that fig. 6 is a specific circuit implementation of the rectifying unit of the variable frequency converter of the present invention.
As shown in fig. 6, in one embodiment, the rectifying unit may be a rectifying circuit composed of a three-phase rectifying bridge, for example. The input end of the inverter is used for receiving the three-phase alternating current output by the transformer T1, and the output end of the inverter is used for outputting the direct current after rectification to the inverter unit. Specifically, the three-phase rectifier bridge can be composed of 18 rectifier diodes D1-D18, wherein the R phase voltage is connected between a first upper bridge (composed of series D1-D3) and a first lower bridge (composed of series D4-D6) in series; the S-phase voltage is connected between a second upper bridge (consisting of D7-D9) and a second lower bridge (consisting of D10-D12) which are connected in series; the T-phase voltage is connected between a third upper bridge (composed of D13-D15) and a third lower bridge (composed of D16-D18) which are connected in series. Further, the output terminals of the rectifier diodes D1, D7 and D13 are connected to a point to serve as the DC + terminal of the DC bus; the input terminals of the rectifier diodes D6, D12 and D18 are connected at a point to act as the DC-terminal of the DC bus. The operating principle of the rectifier circuit is briefly described below.
The output current of the rectifying circuit at any moment flows out from the rectifying diode connected with the phase with the highest potential in the three-phase power, flows to the rectifying diode connected with the phase with the lowest potential through the load, and finally flows back to the power supply. For example, in the case of 0 to 30 degrees, since the T-phase potential is the highest and the S-phase potential is the lowest, the rectifier diodes D15, D14, D13, D12, D11, and D10 are always in the on state during this period, and the remaining diodes are in the off state. Therefore, the current is output by the T phase, flows through D15, D14 and D13 in sequence, then flows through the load, and flows back to the S phase from D12, D11 and D10 in sequence, and the T phase output is the output of the rectifying circuit.
Under the condition of 30-90 degrees, the R-phase has the highest potential and the S-phase has the lowest potential, so that the rectifier diodes D3, D2, D1, D12, D11 and D10 are always in a conducting state in the period of time, and the rest diodes are in a stopping state. Therefore, the current is output by the R phase, flows through the D3, the D2 and the D1 in sequence, then flows through the load, and flows back to the S phase from the D12, the D11 and the D10 in sequence, and the R phase output is the output of the rectifying circuit.
Further, in the case of 90 to 150 degrees, since the R-phase potential is the highest and the T-phase potential is the lowest, the rectifier diodes D3, D2, D1 and D18, D17, D16 are always in the on state during this period, and the remaining diodes are in the off state. Therefore, the current is output by the R phase, flows through the D3, the D2 and the D1 in sequence, then flows through the load, and flows back to the T phase from the D18, the D17 and the D16 in sequence, and the R phase output is the output of the rectifying circuit. By analogy, the output of the rectifier circuit under the condition of 150-360 degrees can be obtained. From the above analysis, it can be seen that, through the alternate conduction of the three groups of rectifier diodes, the rectifier circuit converts the three-phase ac output by the transformer T1 into dc.
Fig. 7 is a circuit schematic diagram illustrating an inverter unit 700 according to an embodiment of the present invention. It will be appreciated that fig. 7 is a specific circuit implementation of the inverting unit of the variable frequency converter of the present invention.
As shown in fig. 7, the inverter unit 700 may include an inverter circuit composed of 6 IGBT modules VT1 to VT 6. Specifically, VT1 and VT2 constitute a first bridge circuit in series, and the U-phase voltage in the three-phase alternating current output by the inverter circuit is taken between VT1 and VT 2. The VT3 and the VT4 are connected in series to form a second bridge circuit, and the V-phase voltage in the three-phase alternating current of the inverter circuit is taken between VT3 and VT 4. The VT5 and the VT6 are connected in series to form a third bridge circuit, and the W phase voltage in the three-phase alternating current of the inverter circuit is taken between VT5 and VT 6. The operation of the inverter circuit will be briefly described.
For convenience of description, one cycle time is divided into t1 to t 6. For a voltage U between the U-phase and the V-phaseUVIn other words, during the time period from t1 to t2, VT1 and VT4 are turned on simultaneously, the U-phase voltage is "+" and the V-phase voltage is "-", then the U-phase voltage is "+", and the V-phase voltage is "-", respectivelyUVIs "+", and UUVIs the bus voltage value. And in the time period from t4 to t5, VT2 and VT3 are simultaneously conducted, the U phase voltage is negative, the V phase voltage is positive, and the U phase voltage is negativeUVIs "-", and UUVIs the bus voltage value.
For voltage U between V phase and W phaseVWIn other words, during the time period from t3 to t4, VT3 and VT6 are turned on simultaneously, the voltage of the V phase is "+", the voltage of the W phase is "-", and the voltage of the U phase is "+", and the voltage of the W phase is "-", respectivelyVWIs "+", and UVWIs the bus voltage value. And in the time period from t6 to t1, VT4 and VT5 are simultaneously conducted, the voltage of the V phase is "-", the voltage of the W phase is "+", and the voltage of the U phase isVWIs "-", and UVWIs the bus voltage value.
For voltage U between W phase and U phaseWUIn other words, during the time period from t5 to t6, VT5 and VT2 are turned on simultaneously, the W phase voltage is "+" and the U phase voltage is "-", then the U phase voltage is "+", and the U phase voltage is "-", respectivelyWUIs "+", and UWUIs the bus voltage value. And in the time period from t2 to t3, VT1 and VT6 are simultaneously conducted, the W phase voltage is negative, the U phase voltage is positive, and the U phase voltage is negativeWUIs "-", and UWUIs the bus voltage value.
From the above analysis, U isUV、UVWAnd UWUThe phases of the three phases are different by 120 degrees, and the amplitude values of the three phases are equal to the direct-current voltage value of the direct-current bus. Therefore, as long as the on and off of the 6 IGBTs are controlled according to a certain rule, the direct current can be inverted into the three-phase alternating current. And the frequency of the inverted three-phase alternating current can be adjusted by changing the pulse width of the PWM signal through the control unit under the premise that the conduction rule is not changed, and further controlling the conduction and cut-off time of the IGBT. In one embodiment, the inverter unit of the present invention may include two inverter circuits as described above, for example, so as to output two paths of 3.3KV three-phase alternating current, wherein the output power of one path may be 1650KW, and the output power of the other path may be 315KW, so as to drive two motors with different power requirements to operate.
In the working process of the power transformation frequency converter, firstly, the alternating current output by the transformer T1 is converted into low-current alternating current after being processed by the pre-charging circuit. Then, the rectifying unit converts the low-current alternating current into low-current direct current, and the energy storage capacitor in the direct current loop is pre-charged by the low-current direct current. When the pre-charging process is completed, the pre-charging circuit is disconnected, and at this time, the alternating current output by the transformer T1 is rectified by the rectifying unit, so as to output direct current. Then, the direct current flows to an inverter unit after being subjected to filtering, energy storage, interference suppression and the like in a direct current loop. Finally, the inversion unit inverts the direct current so as to convert the direct current into alternating current with a frequency different from that of the alternating current output by the transformer T1 and outputs the alternating current to the motor, so that the motor is driven to operate. When the rotating speed of the motor needs to be changed, the control unit calculates the square wave pulse width of the PWM modulated signal by changing the frequency of the modulation signal, and adjusts the on-off time of the IGBT of the inverter according to the square wave pulse width, so that the inverter outputs three-phase alternating current with the frequency different from that of the original three-phase alternating current, and finally the rotating speed of the motor is changed.
It should be understood that the terms "first", "second", "third" and "fourth", etc. in the claims, the description and the drawings of the present invention are used for distinguishing different objects and are not used for describing a particular order. The terms "comprises" and "comprising," when used in the specification and claims of this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and claims of this application, the singular form of "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the term "and/or" as used in the specification and claims of this specification refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.
Although the present invention is described in the above embodiments, the description is only for the convenience of understanding the present invention, and is not intended to limit the scope and application of the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A power conversion converter, comprising:
an incoming line room including a plurality of wiring chambers for receiving and outputting a plurality of three-phase alternating currents having different voltage values through a docking cable;
a rectifying unit for converting the three-phase alternating current output from the inlet room into direct current;
the inverter unit is used for converting the direct current output by the rectifying unit into alternating current with different frequency from the three-phase alternating current received by the wire inlet chamber; and
and the control unit is used for controlling the inversion unit to output the alternating currents with different frequencies.
2. A variable frequency transformer according to claim 1, wherein the wiring chambers of the inlet housing are two and the voltage of the three phase alternating current it receives is 10KV or 600V.
3. A variable frequency converter according to claim 1, further comprising a power transformation unit for converting the voltage values of the three-phase alternating current output from the incoming room.
4. A variable frequency converter according to claim 3, wherein the power transforming unit comprises a transformer having a primary side winding of a double winding structure for connecting the 10KV three-phase alternating current and the 600V three-phase alternating current, respectively, and a secondary side winding of a single winding structure.
5. A variable frequency converter according to claim 1, wherein the incoming line enclosure further comprises a plurality of distribution cabinets for controlling and protecting the plurality of three-phase alternating currents of different voltage values.
6. A variable frequency converter according to claim 1, further comprising:
the first heat dissipation system is positioned at the top of the power transformation unit and used for dissipating heat of the power transformation unit; and
and the second heat dissipation system is positioned at the tops of the rectifying unit and the inverter unit and used for dissipating heat of the rectifying unit and the inverter unit.
7. A variable frequency converter according to claim 1, further comprising a dc link comprising a dc bus and an energy storage capacitor and adapted to filter, buffer and store the dc power output by the rectifying unit.
8. A variable frequency converter according to claim 6, further comprising:
the display cabinet is used as a human-computer interface of the power transformation frequency converter and used for controlling the power transformation frequency converter; and
and the outgoing line cabinet is connected with the inversion unit and is used for outputting the alternating current output by the inversion unit.
9. A variable frequency converter according to claim 8, further comprising:
a first housing accommodating the display cabinet and the wire inlet chamber therein;
a second case that is connected to the first case and accommodates the power conversion unit and the first heat dissipation system therein;
a third case connected to the second case and accommodating the rectifying unit, the inverter unit, and the second heat dissipation system therein; and
a fourth case connected with the third case and accommodating the outlet cabinet therein.
10. The power conversion converter of claim 9, further comprising a base, the first, second, third, and fourth housings being pryed on the base.
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Application publication date: 20210212 |