CN112332743A - Frequency conversion all-in-one machine - Google Patents
Frequency conversion all-in-one machine Download PDFInfo
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- CN112332743A CN112332743A CN202011282467.1A CN202011282467A CN112332743A CN 112332743 A CN112332743 A CN 112332743A CN 202011282467 A CN202011282467 A CN 202011282467A CN 112332743 A CN112332743 A CN 112332743A
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- 238000011105 stabilization Methods 0.000 claims abstract description 5
- 239000003990 capacitor Substances 0.000 claims description 15
- 238000004146 energy storage Methods 0.000 claims description 12
- 230000003139 buffering effect Effects 0.000 claims description 3
- 238000009434 installation Methods 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 9
- 238000012545 processing Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 230000018199 S phase Effects 0.000 description 6
- 230000033228 biological regulation Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
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- 229910001219 R-phase Inorganic materials 0.000 description 2
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- 230000006870 function Effects 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
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- 238000002955 isolation Methods 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
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- 238000004806 packaging method and process Methods 0.000 description 1
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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
- H02P27/08—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 with pulse width modulation
- H02P27/085—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 with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/22—Auxiliary parts of casings not covered by groups H02K5/06-H02K5/20, e.g. shaped to form connection boxes or terminal boxes
- H02K5/225—Terminal boxes or connection arrangements
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Abstract
The invention discloses a frequency conversion all-in-one machine. The frequency conversion all-in-one machine comprises a frequency converter, a reactor and a motor, wherein the frequency converter is arranged in a first box and is used for carrying out frequency conversion on alternating current output by the reactor and outputting the alternating current; the reactor and the motor are arranged in the second box body, wherein the reactor is used for outputting alternating current to the frequency converter after voltage stabilization and interference suppression treatment; and the motor is used for receiving the alternating current output by the frequency converter so as to operate the frequency converter to drive a load. The frequency conversion all-in-one machine adopts a special structure, three structural components of a frequency converter, a reactor and a motor are optimized into two structural components, and the structural form of the two structural components is an up-down structure, so that the compatibility among different systems, the utilization rate of equipment installation space and the stability of the whole structure of the frequency conversion all-in-one machine are improved.
Description
Technical Field
The present invention relates generally to the field of electric machine applications. More specifically, the invention relates to a frequency conversion all-in-one machine.
Background
At present, in working scenes such as coal mines, ports and the like, a motor is often used for driving a belt to transport cargos. In the operation process of the motor, the rotating speed of the motor needs to be changed sometimes according to different goods to be transported and application scenes. However, the existing motor usually has no function of changing the rotation speed, or although the rotation speed of the motor can be changed, a speed regulation method without changing the synchronous rotation speed is adopted, for example, the speed regulation is carried out by adopting chopping speed regulation, cascade speed regulation, and application of an electromagnetic slip clutch, a hydraulic coupler, an oil film clutch, and the like.
Secondly, in the structural design of the existing all-in-one machine, the reactor box body and the motor box body are designed separately and independently installed, and the reactor box body is installed on one side of the frequency converter box body in a suspension mode. Due to the design, the structure of the all-in-one machine is not compact, the whole size is large, and the structure of the all-in-one machine is unstable. In addition, the line-in position of the power supply of the existing all-in-one machine is usually arranged near the frequency conversion component or the reactor box component, and in an actual working scene, the line-in position of the power supply often brings inconvenience due to the influence of the terrain position.
Disclosure of Invention
In order to solve one or more problems in the background art, the invention provides a frequency conversion all-in-one machine which uses a frequency converter, a motor and a reactor in a matching way. The frequency conversion all-in-one machine controls an inversion unit of the frequency converter through the controller, so that three-phase alternating current is subjected to frequency conversion and is output to the motor, and the rotating speed of the motor is changed. In addition, the reactor of the frequency conversion all-in-one machine is arranged at the lower part of the frequency conversion all-in-one machine and is positioned in the same box body with the motor, so that the mechanical structure of the frequency conversion and speed regulation all-in-one machine is simplified, the size of the frequency conversion all-in-one machine is reduced, and the frequency conversion all-in-one machine is more stable in the using process.
The invention discloses a frequency conversion all-in-one machine which comprises a frequency converter, a reactor and a motor. The frequency converter is arranged in a first box and is used for carrying out frequency conversion on the alternating current output by the reactor and outputting the alternating current; the reactor and the motor are arranged in the second box body, wherein the reactor is used for outputting alternating current to the frequency converter after voltage stabilization and interference suppression treatment; and the motor is used for receiving the alternating current output by the frequency converter so as to operate the frequency converter to drive a load.
In one embodiment, the first casing is fixedly coupled to an upper portion of the second casing.
In another embodiment, the frequency converter comprises a rectifying unit, a direct current loop and an inverting unit. Wherein, the rectifier unit is used for converting the alternating current into direct current. The direct current loop comprises a direct current bus and an energy storage capacitor and is used for buffering and storing the direct current output by the rectifying unit. The inverter unit is used for converting the direct current processed by the direct current loop into alternating current with different frequency from the alternating current output by the reactor.
In a further embodiment, a terminal box is arranged on the second box and used for leading an external alternating current cable into the frequency conversion all-in-one machine.
In one embodiment, the junction box is disposed at a side of the second case adjacent to the motor.
In another embodiment, the terminal boxes are respectively arranged on two sides of the second box body along the axial direction of the motor.
According to the frequency conversion all-in-one machine, the reactor is arranged at a special position of the frequency conversion all-in-one machine, so that the problem of unstable structure caused by the fact that the reactor is arranged on the side face of the frequency converter in a suspension mode in the traditional all-in-one machine is solved. Secondly, the frequency conversion all-in-one machine realizes the lead-in of a power cable from a motor part, thereby meeting the special installation requirement of the frequency conversion all-in-one machine. In addition, the frequency conversion all-in-one machine further realizes symmetrical design, and left or right cables can be led in according to requirements, so that the use requirements under different working conditions are met. In addition, the frequency conversion all-in-one machine also has the advantages of simple structure, small volume of the whole machine, stable and reliable operation and the like.
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 schematic diagram showing the components of a frequency conversion all-in-one machine according to an embodiment of the invention;
FIG. 2 is an external structural view showing a variable frequency all-in-one machine according to an embodiment of the present invention;
FIG. 3 is another external structural view showing a variable frequency all-in-one machine according to an embodiment of the present invention;
FIG. 4 is a block diagram illustrating the components of a frequency converter according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a rectifier circuit according to an embodiment of the present invention; and
fig. 6 is a schematic diagram illustrating an inverter circuit 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 block diagram showing the components of a variable frequency all-in-one machine 100 according to an embodiment of the present invention.
As shown in fig. 1, the all-in-one inverter 100 of the present invention may include an inverter 101, a reactor 102, and a motor 103. Wherein the frequency converter is arranged in the first box 104 and is used for converting the frequency of the alternating current output by the reactor and outputting the alternating current. The reactor and the motor are arranged in a second box 105, wherein the reactor is used for outputting alternating current to the frequency converter after voltage stabilization and interference suppression processing. The motor is used for receiving the alternating current output by the frequency converter so as to operate the frequency converter to drive a load.
In one embodiment, the variable frequency all-in-one machine of the invention may further include a controller, which may be a chip or system composed of a central processing unit ("CPU") and a memory, etc., having processing capability and storage capability of analysis, judgment, calculation, etc. The controller can be arranged inside or outside the frequency conversion all-in-one machine and is configured to control the frequency converter to convert the frequency of the alternating current. Further, the controller can be used for monitoring and controlling the running state of the motor and controlling the frequency converter to carry out the pre-charging operation.
In one embodiment, the all-in-one inverter of the invention may further include a transformer, and an output of the transformer is the high-voltage three-phase alternating current. In particular, the transformer may comprise an iron core (or magnetic core) and a coil having two or more windings, wherein the winding connected to the high voltage network is a primary winding and the winding connected to the input of the frequency converter is a secondary winding. The transformer may transform alternating voltage, current and impedance. Generally, the voltage of the high-voltage three-phase alternating current transmitted by the high-voltage power grid is up to 100 kv or more, and the high-voltage three-phase alternating current is not suitable for use in devices such as motors. Therefore, it is necessary to perform voltage reduction processing on the high-voltage three-phase alternating current through a transformer so as to output 6 kv to 10kv to the frequency converter, so that matching between the alternating input voltage and the direct output voltage and high-voltage electrical isolation between the high-voltage power grid and the rectifying unit of the frequency converter can be realized.
Fig. 2 is an external structural view showing a variable frequency all-in-one machine 200 according to an embodiment of the present invention.
As shown in fig. 2, the all-in-one inverter of the invention may include a first box 201, a second box 202, a junction box 203 and a base 204. The first box and the second box may be cuboids, and the first box may be fixedly connected to the second box by bolts or screws. A plurality of holes for passing through cables may be respectively arranged on the connection surfaces between the first case and the second case, wherein the cables may include cables for connecting a reactor and a frequency converter so as to output three-phase alternating current processed by the reactor to the frequency converter. The cable can also comprise a cable for connecting the frequency converter and the motor, so that the three-phase alternating current processed by the frequency converter is output to the motor, and the motor is driven to operate.
Further, the frequency converter may be accommodated in the first case, and the motor and the reactor may be accommodated in the second case. The reactor may include a reactance element, and the reactance element is configured to perform processing such as voltage stabilization and interference suppression on the alternating current externally input to the all-in-one inverter. In one application scenario, a separate base is disposed at a lower portion of the second housing. When the frequency conversion all-in-one machine is placed in a working scene, the base is in contact with the ground, so that the stability of the frequency conversion all-in-one machine is enhanced.
In one embodiment, the junction box may be disposed on the second housing for introducing an external ac cable to the convertible all-in-one machine. Further, the junction box is arranged on one side of the second box body close to the motor. Preferably, the terminal boxes can be respectively arranged on two sides of the second box body along the axial direction of the motor, so that the alternating current cable can be led in from any side of the frequency conversion all-in-one machine according to the requirements of a working scene.
When the frequency conversion all-in-one machine works, an external alternating current cable can be connected with the junction box on one side of the frequency conversion all-in-one machine in a plugging mode. Therefore, three-phase alternating current from the outside is input into the frequency conversion all-in-one machine through the junction box. Then, the three-phase alternating current is output to the reactor through a cable between the reactor and the junction box. Then, the three-phase alternating current processed and output by the reactor is input to the frequency converter through a cable between the reactor and the frequency converter. And finally, inputting the three-phase alternating current processed and output by the frequency converter into the motor through a cable between the frequency converter and the motor so as to drive the motor to run.
In another embodiment, the all-in-one inverter may further include an intermediate end cap for separating the motor and the reactor. Further, the rotating shaft 205 of the motor passes through the middle end cover. And the inner diameter of the middle end cover is in interference connection with the outer ring of the bearing, and the inner ring of the bearing is in interference connection with the rotating shaft of the motor. Through the structural arrangement, the motor rotating shaft can rotate through a bearing, and the middle end cover is used for supporting and fixing the motor bearing. Furthermore, an oil filling hole can be further arranged on the middle end cover and can be arranged on two sides of the frequency conversion all-in-one machine, so that the frequency conversion all-in-one machine can be conveniently used for oil filling and lubricating a bearing of the motor.
In yet another embodiment, the variable frequency all-in-one machine may further include a heat dissipation system. The water channel and the water seat are respectively arranged at the bottom of the first box body and are matched with each other so as to form a water flow passage for radiating the frequency converter. In one application scenario, a circuitous water channel is arranged at the bottom of the frequency converter box body, and an insulated gate bipolar transistor (abbreviated as "IGBT") module of the frequency converter is arranged at the upper part of the water channel. And a variable frequency water channel water inlet and a variable frequency water channel water outlet which are connected with the circuitous water channel are respectively arranged along two sides vertical to the direction of the rotating shaft of the motor. In the operation process of the frequency conversion all-in-one machine, cold water is injected into the water inlet of the frequency conversion water channel, flows in the water channel in the circuitous shape and finally flows out of the water outlet of the frequency conversion water channel, so that the IGBT module of the frequency converter is cooled.
Fig. 3 is another external structural view illustrating the variable frequency all-in-one machine 200 according to the embodiment of the present invention. It can be understood that the all-in-one inverter shown in fig. 3 is obtained by rotating the all-in-one inverter shown in fig. 2 counterclockwise by 90 degrees in the horizontal direction, and the internal structure of the inverter is also shown in fig. 3.
As shown in fig. 3, the frequency converter of the variable frequency all-in-one machine of the invention may include an IGBT module 301. The semiconductor device is a modular semiconductor product formed by bridge packaging of an IGBT chip and a freewheeling diode chip (FWD) through a specific circuit. The packaged IGBT module can be directly applied to equipment such as a frequency converter, a UPS (uninterrupted power supply) and the like. The IGBT module has the characteristics of energy conservation, convenience in installation and maintenance, stable heat dissipation and the like.
In one embodiment, the side of the second case close to the motor may be disposed with the junction box, which may be fixedly connected to the second case by bolts or screws. Further, the other side of the second case near the motor may be disposed with a junction box interface 302. The junction box interface can be provided with a cable connected with the reactor. When the direction of the incoming cable of the frequency conversion all-in-one machine needs to be converted, the junction box on one side of the second box body can be detached quickly, and the junction box is arranged on the other side of the second box body.
In another embodiment, the motor may be a permanent magnet motor, which may include a stator, a rotor, and a shaft. The rotor is fixedly connected with the rotating shaft, bearings are arranged at two ends of the rotating shaft respectively, inner rings of the bearings are in interference connection with the rotating shaft, and outer rings of the two bearings are fixedly connected with the outer end cover 303 and the middle end cover respectively. And when the winding coil receives the three-phase alternating current output by the frequency converter, the rotor rotates through magnetic flux generated by the stator, and then the rotating shaft is driven to rotate.
Fig. 4 is a block diagram illustrating the components of a frequency converter 400 according to an embodiment of the present invention.
As shown in fig. 4, the frequency converter 400 of the present invention may include a precharge circuit 401, a rectification unit 402, a dc loop 403, and an inversion unit 404. In one embodiment, the rectifying unit may include a rectifier and a filter, wherein the rectifier may convert the ac power with high voltage and changing direction and magnitude output by the transformer into a unidirectional pulsating dc power by using a component having a unidirectional conductive characteristic. The filter is used for filtering alternating current components in the pulsating direct current voltage.
In one embodiment, the rectifying unit may be, for example, a rectifying circuit 500 composed of a three-phase rectifying bridge as shown in fig. 5. As shown in fig. 5, the input end of the rectifier circuit is used for receiving the three-phase alternating current (R phase, S phase and T phase), and the output end thereof is used for outputting the direct current after rectification processing. As a specific circuit implementation, 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. According to the above, through the alternate conduction of the three groups of rectifier diodes, finally, the rectifier circuit converts the 10KV high-voltage three-phase alternating current into high-voltage direct current.
In another embodiment, the dc link may include a circuit formed by a dc bus and a storage capacitor. As shown in fig. 4, the DC bus is composed of a DC + terminal and a DC-terminal, and the energy storage capacitor C may include a plurality of capacitors C1, C2, C3, and C4. Further, the energy storage capacitor C may be an electrolytic capacitor. It can be understood that the energy storage capacitor C in the dc circuit in fig. 4 may also be replaced by 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 a further embodiment, the pre-charging circuit is arranged at an input of the rectifying unit and is configured to pre-charge an energy storage capacitor C in the dc loop with the ac power. When the frequency converter is powered up, the charging moment of the electrolytic capacitor in the direct current loop of the frequency converter is equivalent to a short-circuit state before no voltage is built up. In this case, since the dc voltage output from the rectifying unit is extremely high, the charging current is extremely high, and further, there is a possibility that the rectifying diode, the electrolytic capacitor on the dc bus, and other inverter components are damaged. For this reason, in order to limit the charging current from being excessively large, it is necessary to precharge the electrolytic capacitor in the dc circuit.
After the electrolytic capacitor is precharged, the rectifying unit can output direct current to the inverter unit through a direct current loop. Since the motor belongs to an inductive load, the power factor of the motor is not 1 no matter what operation state the motor is. 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 unit may include an inverter circuit composed of a plurality of inverter bridges, and the inverter bridge may be composed of a plurality of IGBT modules. Specifically, the inverter unit may include an inverter bridge, a logic control circuit and a filter circuit, and is configured to convert the dc power output by the dc circuit into ac power with constant frequency and constant voltage or with frequency and voltage regulation for supplying to the permanent magnet motor. Furthermore, the inverter bridge may include an input interface, a voltage start loop, a power switch element, a dc conversion loop, a feedback loop, and the like; the logic control circuit may include parts of a pulse width modulation controller, a carrier wave generator, and a modulation wave generator, and it may be disposed within the controller or its functions may be performed by the controller.
In the working process of the inverter unit, the inverter bridge plays a key role in the process of converting direct current into three-phase alternating current. The on-off of the power switch elements on the upper bridge and the lower bridge is controlled by pulse width modulation signals generated by a logic control circuit, so that three-phase alternating current with 120 degrees of phase difference is obtained on three output ends of an inverter bridge, and the three-phase alternating current is output to the motor. In one embodiment, the power switching elements may be, for example, insulated gate bipolar transistors ("IGBTs") which have the advantages of high input impedance and low turn-on voltage.
The inverter unit is connected with the controller through a communication line, and can communicate with the inverter unit through an RS-485 serial bus. The controller is configured to receive and process the signal transmitted by the inverter unit. And sending a PWM control signal to the inverter unit according to the processing result so as to control the IGBTs to be conducted in turn, thereby changing the frequency of the alternating current output by the inverter unit and further controlling the rotating speed of the motor.
As a specific circuit implementation, the inverter circuit may be the inverter circuit 600 shown in fig. 6 and including 6 IGBT modules VT1 to VT 6. As shown in fig. 6, VT1 and VT2 are connected in series to form a first bridge circuit, and the U-phase voltage of 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 UWUThe amplitude of (2) is a 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 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 current after inversion can be adjusted by changing the change period of the PWM control signal through the controller on the premise of not changing the conduction rule.
In the working process of the frequency converter, firstly, alternating current output by the reactor 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 a low-current direct current, and the energy storage capacitor C in the direct current loop is pre-charged by the low-current direct current. And after the pre-charging process is finished, the pre-charging circuit is disconnected, and the alternating current output by the reactor is rectified by the rectifying unit to further output the direct current. Then, the dc power flows to the inverter unit after being subjected to energy storage, interference suppression, and the like in the dc circuit. And finally, the direct current is subjected to inversion processing by the inversion unit so as to be converted into alternating current with different frequency from the alternating current output by the reactor, and the alternating current is output to the motor, so that the motor is driven to operate. When the rotating speed of the motor needs to be changed, the change period of the PWM signal is changed through the controller to adjust the conduction frequency of the IGBT of the inverter, so that the motor receives three-phase alternating current with different frequencies, and 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 disclosure, 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 (6)
1. A frequency conversion integrated machine comprises a frequency converter, a reactor and a motor, wherein
The frequency converter is arranged in the first box body and is used for carrying out frequency conversion on the alternating current output by the reactor and outputting the alternating current;
the reactor and the motor are arranged in a second box, wherein
The reactor is used for outputting alternating current to the frequency converter after voltage stabilization and interference suppression treatment; and
the motor is used for receiving the alternating current output by the frequency converter so as to operate the frequency converter to drive a load.
2. The variable frequency all-in-one machine according to claim 1, wherein the first box body is fixedly connected to the upper part of the second box body.
3. The variable frequency all-in-one machine according to claim 1, wherein the frequency converter comprises a rectifying unit, a direct current loop and an inverting unit, wherein
The rectifying unit is used for converting the alternating current into direct current;
the direct current loop comprises a direct current bus and an energy storage capacitor and is used for buffering and storing the direct current output by the rectifying unit; and
the inverter unit is used for converting the direct current processed by the direct current loop into alternating current with different frequency from the alternating current output by the reactor.
4. The convertible all-in-one machine of claim 1, wherein a junction box is disposed on the second housing for introducing an external ac cable into the convertible all-in-one machine.
5. The variable frequency all-in-one machine according to claim 4, wherein the junction box is arranged on one side of the second box body close to the motor.
6. The variable-frequency all-in-one machine according to claim 4, wherein the junction boxes are respectively arranged on two sides of the second box body along the axial direction of the motor.
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