CN113114081B - Frequency conversion and power frequency seamless switching control method, controller, system and storage medium - Google Patents

Frequency conversion and power frequency seamless switching control method, controller, system and storage medium Download PDF

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CN113114081B
CN113114081B CN202110244492.9A CN202110244492A CN113114081B CN 113114081 B CN113114081 B CN 113114081B CN 202110244492 A CN202110244492 A CN 202110244492A CN 113114081 B CN113114081 B CN 113114081B
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inverter
controller
motor
voltage
flux linkage
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CN113114081A (en
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华新强
石祥建
丁勇
刘东奇
刘为群
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China Southern Power Grid Peak Shaving And Frequency Modulation Guangdong Energy Storage Technology Co ltd
NR Electric Co Ltd
NR Engineering Co Ltd
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NR Engineering Co Ltd
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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
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/34—Arrangements for starting
    • 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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
    • H02P1/30—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor by progressive increase of frequency of supply to primary circuit of motor
    • 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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/54—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting two or more dynamo-electric motors
    • 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
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/13—Observer control, e.g. using Luenberger observers or Kalman filters
    • 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
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H02P21/141—Flux estimation
    • 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
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H02P21/18—Estimation of position or speed
    • 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
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/24—Vector control not involving the use of rotor position or rotor speed sensors
    • H02P21/26—Rotor flux based control
    • 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
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • 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
    • 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
    • H02P27/12—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 pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control
    • 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
    • H02P2203/00—Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor
    • H02P2203/09—Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder
    • 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
    • H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
    • H02P2207/01—Asynchronous machines

Abstract

The invention discloses a frequency conversion and power frequency seamless switching control method, a controller, a system and a storage medium. The technical scheme of the invention can quickly realize the seamless switching between the variable frequency starting of the asynchronous motor and the power frequency power supply, has no impact in the switching process and reduces the influence on a power grid.

Description

Frequency conversion and power frequency seamless switching control method, controller, system and storage medium
Technical Field
The invention relates to the technical field of motor control, in particular to a frequency conversion and power frequency seamless switching control method, a controller, a system and a storage medium.
Background
The asynchronous motor is widely applied to various industrial occasions due to the advantages of simple structure, low cost, high reliability and the like.
When a traditional motor load is directly started, large current can generate large impact on a power grid, and especially in a micro-grid system, the capacity of power generation source configuration in the system is influenced. With the development of power electronic technology, the variable frequency drive adopts a vector control technology, has the advantages of wide speed regulation range, good dynamic response, energy conservation and the like, and can be used for replacing the direct start of a motor. However, some motor loads only operate at power frequency, and it is not economical to configure a frequency converter for each motor in order to reduce the start-up impact, so that configuring the same set of variable frequency driver for different motor loads can greatly improve the utilization rate of the system. Therefore, the variable frequency driving system is adaptive to different motors, and can be seamlessly switched to power frequency operation after the motors are started.
Disclosure of Invention
In order to solve the technical problems that the asynchronous motor is started by using the variable-frequency driving device and the seamless switching to the power frequency operation is carried out, the invention provides a variable-frequency and power frequency seamless switching control method, a controller, a system and a storage medium, which can realize the variable-frequency starting of the asynchronous motor and the seamless switching to the power frequency operation.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the first aspect of the invention provides a frequency conversion and power frequency seamless switching control method, which is used for seamless switching between asynchronous motor frequency conversion starting and power frequency power supply, and comprises the following steps:
controlling an inverter to drive the asynchronous motor to run to power frequency;
respectively calculating the amplitude U of the grid voltage according to the collected grid voltage and the output voltage of the inverterm_gAnd the amplitude U of the output voltage of the inverterm(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq；
Based on the q-axis component of the grid voltage and the q-axis component of the output voltage of the inverter, the increment delta omega of the set value of the rotating speed of the motor is calculated* rThereby controlling the phase of the output voltage of the inverter;
calculating flux linkage set based on the grid voltage amplitude and the inverter output voltage amplitudeIncrement of value Δ Ψ* rThereby controlling the amplitude of the output voltage of the inverter;
calculating error err between q-axis component of power grid voltage and q-axis component of inverter output voltage in real timeuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumAnd when the two errors are smaller than the threshold value and the preset time constant value is kept, generating a switching control instruction to switch the asynchronous motor to be driven by the power frequency power supply and simultaneously controlling the inverter to stop.
Preferably, the given value increment delta omega of the rotating speed of the motor is calculated* rThe following formula is adopted:
Figure BDA0002963590100000021
wherein k ispsyn1、kisyn1And proportional and integral control parameters of PI regulation.
Preferably, the calculating the flux set point increment Δ Ψ* rThe following formula is adopted:
Figure BDA0002963590100000022
wherein k ispsyn2、kisyn2And proportional and integral control parameters of PI regulation.
Preferably, the full-order observer converts i into a, β according to the motor current and voltagesα,isβ、usα,usβObtaining the observed value omega ^ of the rotating speed of the motorrMagnetic flux linkage observed value psirAnd obtaining an angle observation value theta of the rotor flux linkage according to the rotor flux linkager；
The motor main control loop comprises a flux linkage controller, a rotating speed controller, a current controller, a PWM controller and an inverter;
the given value increment delta omega of the motor rotating speed* rFlux linkage setpoint increment Δ Ψ* rRespectively given value omega of motor speed* rGiven value psi of flux linkage* rThe motor rotation speed reference value omega is obtained by superposition* refAnd the flux linkage reference value Ψ* ref；
Reference value omega of motor speed* refAnd the observed value of the rotation speed omega ^ arMaking difference, and sequentially passing through rotation speed controller, current controller and flux linkage reference value psi* refAnd flux linkage observed value ΨrAfter difference is made, the difference sequentially passes through a flux linkage controller and a current controller, and then a three-phase alternating voltage reference value is obtained through a PWM controller and is used for controlling an inverter.
In a second aspect of the present invention, a variable frequency drive controller is provided, including:
the acquisition unit is used for acquiring network side voltage, inverter side current and inverter side voltage;
the first control unit is used for controlling the inverter to drive the asynchronous motor to operate to power frequency;
a voltage and current calculation unit for calculating the grid voltage amplitude U according to the collected grid voltage and the inverter output voltagem_gAnd the inverter output voltage amplitude Um(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq；
A rotation speed increment calculating unit for calculating the motor rotation speed given value increment delta omega based on the power grid voltage q-axis component and the inverter output voltage q-axis component* rThereby controlling the phase of the inverter output voltage;
a flux linkage increment calculation unit for calculating flux linkage set value increment delta psi based on the grid voltage amplitude and the inverter output voltage amplitude* rThereby controlling the amplitude of the output voltage of the inverter;
a switching judgment unit for calculating error err between q-axis component of grid voltage and q-axis component of inverter output voltage in real timeuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumWhen both errors are less than the threshold value and are guaranteedAnd after the preset time constant value is maintained, generating a switching control instruction to switch the asynchronous motor to be driven by the power frequency power supply and simultaneously controlling the inverter to stop.
Preferably, the given value increment delta omega of the rotating speed of the motor is calculated* mThe following formula is adopted:
Figure BDA0002963590100000031
wherein k ispsyn1、kisyn1And proportional and integral control parameters of PI regulation.
Preferably, the calculated flux linkage setpoint increment Δ Ψ* rThe following formula is adopted:
Figure BDA0002963590100000032
wherein k ispsyn2、kisyn2And proportional and integral control parameters of PI regulation.
Preferably, the variable frequency drive controller further comprises a full-order observer, a flux linkage controller, a rotating speed controller, a current controller and a PWM controller;
i of full-order observer after alpha and beta conversion according to motor current and voltagesα,isβ、usα,usβObtaining the observed value omega ^ of the rotating speed of the motorrMagnetic flux linkage observed value psirAnd obtaining an angle observation value theta of the rotor flux linkage according to the rotor flux linkager；
The given value increment delta omega of the motor rotating speed* rFlux linkage setpoint increment Δ Ψ* rRespectively corresponding to a given value omega of the motor speed* rGiven value psi of sum flux linkage* rThe motor rotation speed reference value omega is obtained by superposition* refAnd the flux linkage reference value Ψ* ref；
Reference value omega of motor speed* refAnd the observed value of the rotational speedrMaking difference and then sequentially passing through a rotating speed controller and a current controllerReference value Ψ of flux linkage* refObservation of flux linkage ΨrAfter difference is made, the difference sequentially passes through a flux linkage controller and a current controller, and then a three-phase alternating voltage reference value is obtained through a PWM controller and is used for controlling an inverter.
The third aspect of the present invention provides a frequency conversion and power frequency seamless switching control system, comprising: the inverter, the inverter side current sensor, the inverter side voltage sensor, the grid branch switch, the inverter branch switch and the variable frequency drive controller are arranged in the grid;
the inverter side current sensor and the inverter side voltage sensor detect the output current and voltage of the inverter and transmit signals to the variable frequency drive controller; the network side voltage sensor detects the voltage of a power grid and transmits a signal to the variable frequency drive controller; the alternating current output end of the inverter is connected with the input end of the motor through the inverter branch switch; the three-phase power frequency alternating current power supply is connected with the input end of the motor through the power grid branch switch; the frequency conversion driving controller controls the asynchronous motor to start in a frequency conversion mode and switch to a power frequency power supply to operate by controlling the inverter, and in the process of starting in the frequency conversion mode, the power grid branch switch is switched off, the inverter branch switch is switched on, and when the frequency conversion driving controller outputs a switching control instruction, the power grid branch switch is controlled to be switched on, and meanwhile, the inverter branch switch is controlled to be switched off and the inverter is stopped.
Preferably, the inverter adopts a two-level three-phase voltage source type topological structure.
In a fourth aspect of the present invention, a computer-readable storage medium is provided, on which a processor program is stored, where the processor program is configured to execute the foregoing method for controlling seamless handover between variable frequency and power frequency.
The invention has the following beneficial effects:
1. the method comprises the following steps that a speed-sensorless vector control technology based on a full-order observer is adopted, and a motor is dragged to a rated rotating speed through variable frequency speed regulation in the starting stage of the asynchronous motor; on the basis of not changing the original vector control structure, the terminal voltage of the motor is controlled to coincide with the voltage vector of the power grid through a switching control strategy, and seamless switching from frequency conversion to power frequency is achieved. The invention always controls the vector coincidence of the terminal voltage of the motor and the voltage of the power grid in the switching process, so the impact in the starting process is small.
2. The system can quickly realize the control of the variable frequency starting of a plurality of asynchronous motors and the switching to the operation of a power frequency power supply, thereby reducing the system cost.
3. The control method of the invention is completely integrated in the variable frequency drive controller and can be compatible with the traditional variable frequency speed regulation control method.
4. The corresponding frequency conversion and power frequency seamless switching control system is applicable to switching operation conditions of frequency conversion and power frequency of multiple asynchronous motors, and is stable and reliable in engineering application.
Drawings
Fig. 1 is a flowchart of a frequency conversion and power frequency seamless switching control method according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a frequency conversion and power frequency seamless switching control method according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of a frequency conversion and power frequency seamless switching control system according to an embodiment of the present invention.
Fig. 4 is a flowchart of another frequency conversion and power frequency seamless switching control method according to an embodiment of the present invention.
Detailed Description
The invention is described in more detail below with reference to the drawings.
Fig. 1 shows an embodiment of a control method for seamless switching between variable frequency and power frequency provided by the present application, which is used for seamless switching between variable frequency start of an asynchronous motor and a power frequency power supply, and includes the following steps:
s101: and controlling the inverter to drive the asynchronous motor to run to power frequency.
S102: respectively calculating the amplitude U of the grid voltage according to the collected grid voltage and the output voltage of the inverterm_gAnd the amplitude U of the output voltage of the inverterm(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq。
S103: base ofCalculating the given value increment delta omega of the motor rotating speed according to the q-axis component of the power grid voltage and the q-axis component of the output voltage of the inverter* rThereby controlling the phase of the inverter output voltage.
S104: based on the grid voltage amplitude and the inverter output voltage amplitude, calculating flux linkage given value increment delta psi* rThereby controlling the magnitude of the inverter output voltage.
S105: calculating error err between q-axis component of power grid voltage and q-axis component of inverter output voltage in real timeuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumAnd when the two errors are smaller than the threshold value and the preset time constant value is kept, generating a switching control instruction to switch the asynchronous motor to be driven by the power frequency power supply and simultaneously controlling the inverter to stop.
In a preferred embodiment, a motor speed setpoint increment Δ ω is calculated* rThe following formula is adopted:
Figure BDA0002963590100000051
wherein k ispsyn1、kisyn1And proportional and integral control parameters of PI regulation.
In a preferred embodiment, the calculating flux set point increment Δ Ψ* rThe following formula is adopted:
Figure BDA0002963590100000052
wherein k ispsyn2、kisyn2And proportional and integral control parameters of PI regulation.
Fig. 2 is a schematic diagram of a frequency conversion and power frequency seamless switching control method according to an embodiment of the present invention. The rotating speed self-adaptive full-order observer performs alpha and beta conversion on the i according to the current and the voltage of the motorsα,isβ、usα,usβObtaining the observed value omega ^ of the rotating speed of the motorrMagnetic flux linkage observed value psirAnd obtaining an angle observation value theta of the rotor flux linkage according to the rotor flux linkager. The motor main control loop comprises a flux linkage controller, a rotating speed controller, a current controller, a PWM controller and an inverter. The invention calculates the given value increment delta omega of the motor rotating speed by steps S103 and S104 in the control method according to the embodiment of the application through the superposition of the front ends of the flux linkage controller and the rotating speed controller* rFlux-sum given value increment Δ Ψ* rRespectively corresponding to a given value omega of the motor speed* rGiven value psi of flux linkage* rThe motor rotation speed reference value omega is obtained by superposition* refAnd the flux linkage reference value Ψ* ref. Reference value omega of motor speed* refAnd the observed value of the rotational speedrAfter difference is made, the difference passes through a rotating speed controller, a current controller and a flux linkage reference value psi in sequence* refAnd flux linkage observed value ΨrAfter difference is made, the difference sequentially passes through a flux linkage controller and a current controller, and then a three-phase alternating voltage reference value is obtained through a PWM controller and is used for controlling an inverter.
The method and the device adjust the flux linkage of the motor rotor in a closed loop mode through the difference between the power grid voltage Uq _ g and the motor terminal voltage Uq; the rotating speed of the motor is adjusted in a closed loop mode through the difference between the power grid voltage Ud _ g and the motor end voltage Ud until the difference is 0, the motor end voltage is considered to be completely consistent with the power grid voltage at the moment, and the inverter can complete power supply to be switched to the power grid power supply at the moment.
The embodiment of the application provides a frequency conversion drive controller includes:
the acquisition unit is used for acquiring network side voltage, inverter side current and inverter side voltage;
the first control unit is used for controlling the inverter to drive the asynchronous motor to operate to power frequency;
a voltage and current calculating unit for calculating the grid voltage amplitude U according to the collected grid voltage and the inverter output voltagem_gAnd the inverter output voltage amplitude Um(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq；
A rotation speed increment calculation unit for calculating a motor rotation speed given value increment delta omega based on the power grid voltage q-axis component and the inverter output voltage q-axis component* rThereby controlling the phase of the inverter output voltage;
a flux linkage increment calculation unit for calculating flux linkage set value increment delta psi based on the grid voltage amplitude and the inverter output voltage amplitude* rThereby controlling the amplitude of the output voltage of the inverter;
a switching judgment unit for calculating the error err between the q-axis component of the grid voltage and the q-axis component of the inverter output voltage in real timeuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumAnd when the two errors are smaller than the threshold value and the preset time constant value is kept, generating a switching control instruction to switch the asynchronous motor to be driven by the power frequency power supply and simultaneously controlling the inverter to stop.
In some embodiments, a motor speed setpoint increment Δ ω is calculated* rThe following formula is adopted:
Figure BDA0002963590100000061
wherein k ispsyn1、kisyn1Proportional and integral control parameters for PI regulation;
calculating flux linkage set point increment delta psi* rThe following formula is adopted:
Figure BDA0002963590100000062
wherein k ispsyn2、kisyn2And proportional and integral control parameters of PI regulation.
In some embodiments, the variable frequency drive controller further comprises a full-order observer, a flux linkage controller, a rotation speed controller, a current controller, a PWM controller;
the full-order observer is used for observing the current and the voltage of the motorI after alpha, beta conversionsα,isβ、usα,usβObtaining the observed value omega ^ of the rotating speed of the motorrMagnetic flux linkage observed value psirAnd obtaining an angle observation value theta of the rotor flux linkage according to the rotor flux linkager；
The given value increment delta omega of the motor rotating speed* rFlux-sum given value increment Δ Ψ* rRespectively corresponding to a given value omega of the motor speed* rGiven value psi of flux linkage* rThe motor rotation speed reference value omega is obtained by superposition* refAnd the flux linkage reference value Ψ* ref；
Reference value omega of motor speed* refAnd the observed value of the rotation speed omega ^ arAfter difference is made, the difference passes through a rotating speed controller, a current controller and a flux linkage reference value psi in sequence* refAnd flux linkage observed value ΨrAfter the difference is made, the difference sequentially passes through the flux linkage controller and the current controller, and then a three-phase alternating voltage reference value is obtained through the PWM controller and is used for controlling the inverter.
As shown in fig. 3, a frequency conversion and power frequency seamless switching control system provided in an embodiment of the present application includes: an inverter, an inverter-side current sensor, an inverter-side voltage sensor, a grid branch switch, an inverter branch switch, and a variable frequency drive controller as described above. The inverter side current sensor and the inverter side voltage sensor detect the output current and voltage of the inverter and transmit signals to the variable frequency drive controller; the network side voltage sensor detects the voltage of a power grid and transmits a signal to the variable frequency drive controller; the alternating current output end of the inverter is connected with the input end of the motor through the inverter branch switch; the three-phase power frequency alternating current power supply is connected with the input end of the motor through the power grid branch switch; the frequency conversion driving controller controls the asynchronous motor to start in a frequency conversion mode and switch to a power frequency power supply to operate by controlling the inverter, and in the process of starting in the frequency conversion mode, the power grid branch switch is switched off, the inverter branch switch is switched on, and when the frequency conversion driving controller outputs a switching control instruction, the power grid branch switch is controlled to be switched on, and meanwhile, the inverter branch switch is controlled to be switched off and the inverter is stopped. In some embodiments, the inverter employs a two-level, three-phase voltage source type topology.
In combination with the frequency conversion and power frequency seamless switching control system shown in fig. 3, the specific switching steps adopted are shown in fig. 4, and include:
step S201, controlling the power grid branch switch of the asynchronous motor to be switched off, and switching on the inverter branch switch;
step S202, starting an inverter and driving an asynchronous motor to operate to power frequency;
the method for judging whether the asynchronous motor runs to the power frequency is that whether the error between the frequency of the output voltage of the inverter and the power frequency is smaller than a fixed value or not is detected, if yes, the step S203 is executed, and if not, the asynchronous motor is continuously driven to run to the power frequency; in practice, the constant value may be set to 1 Hz;
step S203, respectively calculating the power grid voltage amplitude U by using the acquired power grid voltage and the inverter output voltagem_gAnd the inverter output voltage amplitude Um(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq；
Step S204, calculating the given value increment delta omega of the motor rotating speed according to the following formula by the switching control module by utilizing the calculated q-axis component of the grid voltage and the q-axis component of the inverter output voltage* mThereby controlling the phase of the inverter output voltage;
Figure BDA0002963590100000071
wherein k ispsyn1、kisyn1Proportional and integral control parameters;
step S205, using the grid voltage amplitude and the inverter output voltage amplitude obtained by calculation, calculating flux linkage given value increment delta psi by the switching control module according to the following formula* mThereby controlling the amplitude of the output voltage of the inverter;
Figure BDA0002963590100000081
step S06, calculating error err between the q-axis component of the grid voltage and the q-axis component of the output voltage of the inverter in real timeuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumIf both the two errors are smaller than the threshold value and remain stable for a period of time, it is determined that the switching condition is satisfied, and step S207 is entered; if the switching condition is not satisfied, continuing to sequentially implement steps S203-S06;
and step S07, outputting a switching control command by the variable-frequency drive controller, controlling the switching-on of the power grid branch switch of the asynchronous motor, and simultaneously switching-off the branch switch of the inverter to stop the inverter.
The embodiment of the invention also provides a computer readable storage medium, wherein a processor program is stored on the computer readable storage medium, and the processor program is used for executing the frequency conversion and power frequency seamless switching control method.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method or computer program product. The present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims (8)

1. A frequency conversion and power frequency seamless switching control method is used for seamless switching between asynchronous motor frequency conversion starting and a power frequency power supply, and is characterized by comprising the following steps:
controlling an inverter to drive an asynchronous motor to run to power frequency;
respectively calculating the amplitude U of the grid voltage according to the collected grid voltage and the output voltage of the inverterm_gAnd the amplitude U of the output voltage of the inverterm(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq；
Based on the q-axis component of the grid voltage and the q-axis component of the output voltage of the inverter, the increment delta omega of the set value of the rotating speed of the motor is calculated* rThereby controlling the phase of the output voltage of the inverter;
based on the grid voltage amplitude and the inverter output voltage amplitude, calculating flux linkage given value increment delta psi* rThereby controlling the amplitude of the output voltage of the inverter;
real-time calculation of grid voltageError err between q-axis component and inverter output voltage q-axis componentuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumWhen both errors are smaller than the threshold value and the preset time constant value is kept, a switching control instruction is generated to switch the asynchronous motor to be driven by the power frequency power supply, and the inverter is controlled to stop;
i of full-order observer after alpha and beta conversion according to motor current and voltagesα,isβ、usα,usβObtaining the observed value of the motor speed
Figure FDA0003656685480000011
Flux linkage observation ΨrAnd obtaining an angle observation value theta of the rotor flux linkage according to the rotor flux linkager；
The motor main control loop comprises a flux linkage controller, a rotating speed controller, a current controller, a PWM controller and an inverter;
the given value increment delta omega of the motor rotating speed* rFlux-sum given value increment Δ Ψ* rRespectively corresponding to a given value omega of the motor speed* rGiven value psi of flux linkage* rThe motor rotation speed reference value omega is obtained by superposition* refAnd the flux linkage reference value Ψ* ref；
Reference value omega of motor speed* refAnd observed value of rotating speed
Figure FDA0003656685480000012
After difference is made, the difference passes through a rotating speed controller, a current controller and a flux linkage reference value psi in sequence* refAnd flux linkage observed value ΨrAfter difference is made, the difference sequentially passes through a flux linkage controller and a current controller, and then a three-phase alternating voltage reference value is obtained through a PWM controller and is used for controlling an inverter.
2. The method for controlling seamless switching between variable frequency and power frequency according to claim 1, wherein the method for calculating the given value increment of the rotation speed of the motor, Δ ω, is characterized in that* rAdopts the following stepsThe formula is as follows:
Figure FDA0003656685480000013
wherein k ispsyn1、kisyn1And proportional and integral control parameters of PI regulation.
3. The method according to claim 1, wherein the calculating of the flux linkage setpoint increment Δ Ψ is based on a time-domain power-frequency seamless transition control scheme* rThe following formula is adopted:
Figure FDA0003656685480000021
wherein k ispsyn2、kisyn2And proportional and integral control parameters of PI regulation.
4. A variable frequency drive controller, comprising:
the acquisition unit is used for acquiring network side voltage, inverter side current and inverter side voltage;
the first control unit is used for controlling the inverter to drive the asynchronous motor to operate to power frequency;
a voltage and current calculating unit for calculating the grid voltage amplitude U according to the collected grid voltage and the inverter output voltagem_gAnd the amplitude U of the output voltage of the inverterm(ii) a And respectively calculating the q-axis component u of the grid voltage under the rotor magnetic field synchronous rotation coordinate systemq_gAnd the q-axis component u of the inverter output voltageq；
A rotation speed increment calculating unit for calculating the motor rotation speed given value increment delta omega based on the power grid voltage q-axis component and the inverter output voltage q-axis component* rThereby controlling the phase of the inverter output voltage;
a flux linkage increment calculation unit for calculating based on the grid voltage amplitude and the inverter output voltage amplitudeFlux linkage set point increment Δ Ψ* rThereby controlling the amplitude of the output voltage of the inverter;
a switching judgment unit for calculating the error err between the q-axis component of the grid voltage and the q-axis component of the inverter output voltage in real timeuqAnd the error err between the grid voltage amplitude and the inverter output voltage amplitudeumWhen both errors are smaller than the threshold value and the preset time constant value is kept, a switching control instruction is generated to switch the asynchronous motor to be driven by the power frequency power supply, and the inverter is controlled to stop;
the full-order observer, the flux linkage controller, the rotating speed controller, the current controller and the PWM controller are further included;
i of full-order observer after alpha and beta conversion according to motor current and voltagesα,isβ、usα,usβObtaining the observed value of the rotating speed of the motor
Figure FDA0003656685480000022
Flux linkage observation ΨrAnd obtaining an angle observation value theta of the rotor flux linkage according to the rotor flux linkager；
The given value increment delta omega of the motor rotating speed* rFlux-sum given value increment Δ Ψ* rRespectively corresponding to a given value omega of the motor speed* rGiven value psi of flux linkage* rThe motor rotation speed reference value omega is obtained by superposition* refAnd the flux linkage reference value Ψ* ref；
Reference value omega of motor speed* refAnd observed value of rotation speed
Figure FDA0003656685480000023
After difference is made, the difference passes through a rotating speed controller, a current controller and a flux linkage reference value psi in sequence* refAnd flux linkage observed value ΨrAfter difference is made, the difference sequentially passes through a flux linkage controller and a current controller, and then a three-phase alternating voltage reference value is obtained through a PWM controller and is used for controlling an inverter.
5. The variable frequency drive controller of claim 4 wherein the calculated motor speed setpoint increment Δ ω is calculated* rThe following formula is adopted:
Figure FDA0003656685480000031
wherein k ispsyn1、kisyn1Proportional and integral control parameters for PI regulation;
the calculated flux linkage set point increment Δ Ψ* rThe following formula is adopted:
Figure FDA0003656685480000032
wherein k ispsyn2、kisyn2And proportional and integral control parameters of PI regulation.
6. The utility model provides a frequency conversion and seamless handover control system of power frequency which characterized in that includes: an inverter, an inverter-side current sensor, an inverter-side voltage sensor, a grid-leg switch, an inverter-leg switch, and a variable frequency drive controller as claimed in any one of claims 4 to 5;
the inverter side current sensor and the inverter side voltage sensor detect the output current and voltage of the inverter and transmit signals to the variable frequency drive controller; the network side voltage sensor detects the voltage of a power grid and transmits a signal to the variable frequency drive controller; the alternating current output end of the inverter is connected with the input end of the motor through the inverter branch switch; the three-phase power frequency alternating current power supply is connected with the input end of the motor through a power grid branch switch; the frequency conversion driving controller controls the asynchronous motor to start in a frequency conversion mode and switch to a power frequency power supply to operate by controlling the inverter, and in the process of starting in the frequency conversion mode, the power grid branch switch is switched off, the inverter branch switch is switched on, and when the frequency conversion driving controller outputs a switching control instruction, the power grid branch switch is controlled to be switched on, and meanwhile, the inverter branch switch is controlled to be switched off and the inverter is stopped.
7. The system of claim 6, wherein the inverter is in a two-level three-phase voltage source topology.
8. A computer-readable storage medium, having stored thereon a processor program, wherein the processor program is adapted to perform the method of any of claims 1 to 3.
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