CN110545063B - Reactor-free control method for switching power frequency of high-voltage frequency converter to frequency conversion - Google Patents
Reactor-free control method for switching power frequency of high-voltage frequency converter to frequency conversion Download PDFInfo
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- CN110545063B CN110545063B CN201910872597.1A CN201910872597A CN110545063B CN 110545063 B CN110545063 B CN 110545063B CN 201910872597 A CN201910872597 A CN 201910872597A CN 110545063 B CN110545063 B CN 110545063B
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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
- 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
- H02P27/02—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using supply voltage with constant frequency and variable amplitude
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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
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Abstract
The invention relates to a reactor-free control method for switching power frequency of a high-voltage frequency converter to frequency conversion, belonging to the field of power electronics. The method comprises the steps that a voltage detection module is used for detecting a motor stator voltage signal, phase-locking calculation is carried out on the motor stator voltage signal to obtain a voltage amplitude and an angle of a motor stator side, and when a switching instruction is obtained, a control mode that a power frequency contactor is firstly opened and then a variable frequency contactor is closed is adopted; the frequency converter adjusts the three-phase output fundamental wave initial phase angle and the superposed third harmonic initial phase angle, the amplitude and the modulation degree according to the detected amplitude of the motor stator voltage, and realizes the control of output current without impact. The invention can realize smooth undisturbed switching under the condition of no output reactor, thereby reducing the equipment cost; synchronous operation control of the frequency converter and the power frequency power supply is not needed, and rapid switching is achieved.
Description
Technical Field
The invention belongs to the field of power electronics, and relates to a reactor-free control method for switching power frequency of a high-voltage frequency converter to frequency conversion, which is suitable for a frequency converter control system similar to a dragging alternating current rotating motor.
Background
The high-voltage frequency converter adopts a multi-level series voltage doubling mode and has the perfect output of high-quality sinusoidal voltage and sinusoidal current of variable frequency voltage (VVVF). However, the power electronic devices are complex in composition and need to be maintained at regular time or maintained at irregular time, so that the power frequency side and the frequency converter need to be switched at irregular time, and a reliable undisturbed switching technology is needed between the high-voltage frequency converter and the power frequency power supply to avoid huge economic loss caused by repeated shutdown.
At present, a method for undisturbed switching of multiple power frequencies is provided, a hot switching mode is commonly used, the mode needs a synchronous process of a frequency converter and the power frequencies, an output reactor needs to be additionally arranged, the control is complex, and the equipment cost is high; in order to avoid the difficulty of synchronous control and reduce the cost of the reactor, various mature modes are available for a control method for switching frequency conversion to power frequency, and the invention does not relate to the control method; for the control method of switching the power frequency to the frequency conversion, some methods adopt a mode that after the power frequency power supply is disconnected, the frequency converter starts the runaway, and the method is generally low in switching speed and easy to cause large load disturbance.
Therefore, a control method which does not need an output reactor and can simply and quickly switch the power frequency operation to the high-voltage frequency converter operation is needed.
Disclosure of Invention
In view of the above, the present invention provides a reactor-free control method for switching power frequency of a high-voltage inverter to frequency conversion, in which a detection signal of a stator voltage of a motor is used to adjust an output of the inverter, so that a control effect of no current impact and no rotation speed disturbance is achieved during switching.
In order to achieve the purpose, the invention provides the following technical scheme:
a reactor-free control method for switching power frequency of a high-voltage frequency converter to frequency conversion specifically comprises the following steps:
s1: when a switching instruction is obtained, starting the frequency converter to a ready state;
s2: detecting the voltage signal of the motor stator by using a voltage detection module, and performing phase-locked calculation on the detected voltage signal to obtain the actual frequency F of the motor statorreqmThree-phase fundamental voltage angle thetamSum voltage amplitude Um；
S3: compensating the detected signal, and pre-estimating the output modulation degree m and voltage fundamental wave phase angle theta of the frequency converter for PWM calculationinv；
S4: disconnecting the power frequency contactor;
s5: closing the frequency converter contactor;
s6: enabling the output pulse to enter frequency conversion control.
Further, in step S1, the ready state is: and after all the units of the frequency converter are charged and reset, the controller keeps the power electronic device in a full-off state and performs pulse control on the power electronic device at any time, so that the frequency converter outputs a specified voltage signal.
Further, the step S2 specifically includes: collecting motor stator voltage A phase UmaAnd B phase UmbObtaining the actual frequency F of the power frequency voltage signal by adopting a software phase-locked loop algorithmreqmAnd three-phase fundamental voltage angle thetamObtaining the voltage amplitude U by adopting a three-phase effective value algorithmm。
Further, in step S3, it is estimated that the output modulation degree of the inverter is m ═ Um/UdcWherein U isdcIs the average value of three-phase DC bus voltage, UmObtaining a voltage amplitude by adopting a three-phase effective value algorithm; the angle of the output voltage of the frequency converter is estimated to be thetainv＝θm+θcompWherein thetacompIs the angle of one switching cycle duration; estimated output frequency of Freqm。
Further, in step S4, the power frequency contactor is a contactor in which a power frequency power supply is connected to the motor.
Further, in step S5, the variable frequency contactor is a contactor whose frequency converter output is connected to the motor.
Further, in step S6, the entering of the variable frequency control includes: keeping the output frequency unchanged, linearly changing the output modulation degree as a target slope according to the voltage amplitude calculated by the VF curve, and when the output modulation degree reaches the VF curve, operating the output voltage and the frequency to a target rotating speed according to a conventional operation mode.
Further, the reactor-free control system suitable for switching the power frequency of the high-voltage frequency converter to frequency conversion comprises a voltage detection module, a signal processing and PWM calculation module and an IO control module;
the voltage detection module is used for detecting the motor stator voltage A phase UmaAnd B phase Umb；
The signal processing and PWM calculation module performs phase-locked calculation on the detected voltage signal, performs pre-estimation calculation on the amplitude and the angle of the output voltage of the frequency converter, and finally outputs a proper PWM pulse to drive an H-bridge power unit module in the frequency converter;
and the IO control module is used for detecting and controlling the state of the contactor and carrying out corresponding switching action according to the switching requirement.
The invention has the beneficial effects that: the control method can realize that the power frequency power supply is smoothly switched to the frequency converter for power supply when no output reactor exists, thereby saving the space and the cost of equipment; the control is simple, the synchronous control of a power frequency power supply and a frequency converter is not needed, and the quick switching is realized.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of a switching control system according to the present invention;
fig. 2 is a flowchart of a handover control method according to the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Referring to fig. 1 to 2, fig. 1 is a control system for switching a power frequency of a high-voltage inverter to a variable frequency in a preferred embodiment of the present invention, wherein the power frequency power supply is a 10kV power supply, the inverter is an 8-level H-bridge unit cascaded high-voltage inverter, an input of the H-bridge unit is 660V ac voltage for driving a 2000kW motor, and the control system includes a voltage detection module, a signal processing and PWM calculation module, and an IO control module.
A voltage detection module for detecting the motor stator voltage A phase UmaAnd B phase Umb；
The signal processing and PWM calculation module is used for performing phase-locked calculation on the detected voltage signal, performing pre-estimation calculation on the amplitude and the angle of the output voltage of the frequency converter, and finally outputting a proper PWM pulse to drive an H-bridge power unit module in the frequency converter;
and the IO control module is used for detecting and controlling the state of the contactor and carrying out corresponding switching action according to the switching requirement.
Fig. 2 is a flowchart of a control method for smoothly switching the power supply to the high-voltage inverter in this embodiment, which includes the following steps:
the method comprises the following steps: and when a switching instruction is obtained, the KM1 is closed, the frequency converter is started to be in a ready state, the step two and the step three are simultaneously carried out when the frequency converter is in the ready state, the pulse output is forbidden, and the power electronic device is kept in a full-off state.
Step two: collecting motor stator voltage UmaAnd UmbObtaining three-phase fundamental voltage angle theta by adopting software phase-locked loop algorithmmAnd frequency of industrial frequency voltage FreqmObtaining the voltage amplitude U by adopting a three-phase effective value algorithmacm。
Step three: the output modulation degree of the estimated output frequency converter is m ═ Um/UdcWherein U isdcThe estimated output variable frequency voltage angle is theta for the average value of the three-phase direct current bus voltageinv＝θm+θcompWherein thetacompFor an angle of a switching period duration, the estimated output frequency is Freqm。
Step four: and the control system sends a power frequency contactor disconnection instruction 1s after receiving the ready state, and disconnects the power frequency contactor KM3 to quit power frequency operation.
Step five: and after receiving the disconnection state of the power frequency contactor KM3, the control system closes the variable frequency contactor KM2 and puts the variable frequency contactor into a frequency converter.
Step six: after receiving the closed state of the variable frequency contactor KM2, the control system enables pulse output, outputs PWM pulse according to the results of the second step and the third step, and enters the control of the frequency converter, and the voltage amplitude of the motor is reduced to be below the normal operation voltage, so the following adjustments are made:
keeping the output frequency unchanged, linearly changing the output modulation degree as a target slope according to the voltage amplitude calculated by the VF curve, and when the output modulation degree reaches the VF curve, operating the output voltage and the frequency to a target rotating speed according to a conventional operation mode.
In the control method, in the switching process, the impact current of the motor does not exceed 1.2 times of the rated current, the switching time is about 180ms and is about equal to the sum of the closing time of the variable-frequency contactor KM2 and the refreshing cycle time of the PLC.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (6)
1. A reactor-free control method for switching power frequency of a high-voltage frequency converter to frequency conversion is characterized by comprising the following steps:
s1: when a switching instruction is obtained, starting the frequency converter to a ready state;
s2: detecting the voltage signal of the motor stator by using a voltage detection module, and performing phase-locked calculation on the detected voltage signal to obtain the actual frequency F of the motor statorreqmThree-phase fundamental voltage angle thetamSum voltage amplitude Um；
S3: compensating the detected signal, and estimating the output modulation degree of the frequency converter as m ═ Um/UdcWherein U isdcIs the average value of three-phase DC bus voltage, UmObtaining a voltage amplitude by adopting a three-phase effective value algorithm; pre-estimated frequency conversionThe output voltage angle of the device is thetainv＝θm+θcompWherein thetacompAngle of duration of one switching cycle, thetamIs a three-phase fundamental voltage angle; estimated output frequency of Freqm；
S4: disconnecting the power frequency contactor;
s5: closing the frequency converter contactor;
s6: enabling the output pulse to enter frequency conversion control;
entering frequency conversion control comprises: keeping the output frequency unchanged, linearly changing the output modulation degree as a target slope according to the voltage amplitude calculated by the VF curve, and when the output modulation degree reaches the VF curve, operating the output voltage and the frequency to a target rotating speed according to a conventional operation mode.
2. The reactor-free control method for switching power frequency of the high-voltage inverter to frequency conversion according to claim 1, wherein in the step S1, the ready state is: and after all the units of the frequency converter are charged and reset, the controller keeps the power electronic device in a full-off state and performs pulse control on the power electronic device at any time, so that the frequency converter outputs a specified voltage signal.
3. The reactor-free control method for switching power frequency of the high-voltage inverter to frequency conversion according to claim 1, wherein the step S2 specifically comprises: collecting motor stator voltage A phase UmaAnd B phase UmbObtaining the actual frequency F of the power frequency voltage signal by adopting a software phase-locked loop algorithmreqmAnd three-phase fundamental voltage angle thetamObtaining the voltage amplitude U by adopting a three-phase effective value algorithmm。
4. The reactor-free control method for switching power frequency of the high-voltage inverter to variable frequency according to claim 1, wherein in the step S4, the power frequency contactor is a contactor for connecting a power frequency power supply to a motor.
5. The reactor-free control method for switching power frequency of the high-voltage inverter to variable frequency according to claim 1, wherein in the step S5, the variable frequency contactor is a contactor in which an output of the inverter is connected to a motor.
6. The reactor-free control system for switching the power frequency of the high-voltage frequency converter to the variable frequency is suitable for the method of any one of claims 1 to 5, and is characterized by comprising a voltage detection module, a signal processing and PWM calculation module and an IO control module;
the voltage detection module is used for detecting the motor stator voltage A phase UmaAnd B phase Umb；
The signal processing and PWM calculation module performs phase-locked calculation on the detected voltage signal, performs pre-estimation calculation on the amplitude and the angle of the output voltage of the frequency converter, and finally outputs a proper PWM pulse to drive an H-bridge power unit module in the frequency converter;
and the IO control module is used for detecting and controlling the state of the contactor and carrying out corresponding switching action according to the switching requirement.
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| CN201910872597.1A CN110545063B (en) | 2019-09-16 | 2019-09-16 | Reactor-free control method for switching power frequency of high-voltage frequency converter to frequency conversion |
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| CN111371373B (en) * | 2020-04-27 | 2022-03-01 | 新风光电子科技股份有限公司 | Control method for switching high-voltage frequency converter from power frequency undisturbed to frequency conversion |
Citations (3)
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| CN201130918Y (en) * | 2007-12-19 | 2008-10-08 | 叶念国 | Controller for switching bidirectional power supply of AC motor |
| CN104579101A (en) * | 2014-12-02 | 2015-04-29 | 苏州汇川技术有限公司 | Control system and control method for switching variable frequency into power frequency by high-voltage frequency converter |
| CN105676742A (en) * | 2016-03-14 | 2016-06-15 | 广东明阳龙源电力电子有限公司 | Control method for non-disturbance switching between power frequency and variable frequency of high-voltage inverter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2858319B2 (en) * | 1989-01-30 | 1999-02-17 | 松下電器産業株式会社 | Multi-axis synchronous drive device and gear machining device |
| JP4552466B2 (en) * | 2004-03-12 | 2010-09-29 | 株式会社日立製作所 | AC motor control device, 2-chip inverter and one-chip inverter. |
| JP2006320074A (en) * | 2005-05-11 | 2006-11-24 | Toyota Motor Corp | Ac voltage output unit |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201130918Y (en) * | 2007-12-19 | 2008-10-08 | 叶念国 | Controller for switching bidirectional power supply of AC motor |
| CN104579101A (en) * | 2014-12-02 | 2015-04-29 | 苏州汇川技术有限公司 | Control system and control method for switching variable frequency into power frequency by high-voltage frequency converter |
| CN105676742A (en) * | 2016-03-14 | 2016-06-15 | 广东明阳龙源电力电子有限公司 | Control method for non-disturbance switching between power frequency and variable frequency of high-voltage inverter |
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