CN118432458A - Control method, control device, control equipment, control medium and control program product for Vienna rectifier - Google Patents
Control method, control device, control equipment, control medium and control program product for Vienna rectifier Download PDFInfo
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Abstract
The application relates to a control method, a control device, a control medium and a control program product of a Vienna rectifier. Wherein the Vienna rectifier is for a charging device, the method comprising: acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced; determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave; and acquiring network side current of the Vienna rectifier, determining the duty ratio of each phase of switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase of switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function. The method can inhibit the fluctuation of the neutral point position of the direct-current side capacitor and the distortion of the emission current, and can improve the stability of the charging process and the safety of the charging equipment.
Description
Technical Field
The present application relates to the field of power electronics, and in particular, to a method, an apparatus, a computer device, a storage medium, and a computer program product for controlling a Vienna rectifier.
Background
The Vienna rectifier is a bridge rectifier that can be used to convert alternating current to direct current. Vienna rectifier adds inductance element and extra capacitance in bridge rectifier, can promote output voltage quality and reduce harmonic distortion, through adopting vector control strategy, can realize the accurate control to voltage and electric current, promotes the dynamic response and the stability of system. The Vienna rectifier has the advantages of high power factor, fewer switching devices, low switching stress, no switching dead zone problem, high reliability and the like, so that the Vienna rectifier is widely applied to the fields of direct current charging, power transmission and distribution, energy conversion and storage, industrial drivers and the like of electric automobiles.
When the Vienna rectifier is applied to direct current charging equipment, the charging efficiency can be improved through power factor correction, but when the load changes or the condition of a power grid changes, the potential of a neutral point of a direct current side capacitor can fluctuate, and the fluctuation of the potential can possibly cause the direct current voltage output by the charging equipment to change or the distortion of emission current, so that the stability of a charging process and the safety of the charging equipment are influenced, and even harmonic pollution in the power grid or the normal operation of other power equipment is caused.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a control method, apparatus, computer device, computer-readable storage medium, and computer program product for a Vienna rectifier capable of suppressing point-to-point fluctuations and harmonic emissions of a dc-side capacitive neutral point in a charging device.
In a first aspect, the present application provides a control method of a Vienna rectifier, the Vienna rectifier being used for a charging device, the method comprising:
acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced; the working electrical parameters comprise a network side voltage amplitude phase angle, charging power and a network side inductance value;
Determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
And acquiring network side current of the Vienna rectifier, determining the duty ratio of each phase of switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase of switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
In one embodiment, the method further comprises:
Acquiring a voltage difference between a first capacitor and a second capacitor of a direct current side of the Vienna rectifier;
A capacitance difference control amount for suppressing the neutral point voltage fluctuation of the Vienna rectifier is determined from the voltage difference.
In one embodiment, obtaining the operating electrical parameters of the Vienna rectifier with the network side voltage sinusoidal and three-phase balanced includes:
acquiring three-phase voltage and three-phase current of a main circuit of the Vienna rectifier;
And carrying out three-phase-two-phase conversion on the three-phase voltage and the three-phase current to obtain a main circuit current and a main circuit voltage under a two-phase coordinate system, wherein the main circuit current and the main circuit voltage under the two-phase coordinate system are used as working electric parameters of the Vienna rectifier.
In one embodiment, determining a zero sequence modulation amount required to be injected for suppressing the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier; comprising the following steps:
Acquiring a relation function between a zero sequence component of a target modulation wave and a capacitance differential pressure control quantity;
solving a relation function by taking eliminating the neutral point voltage fluctuation as a target to obtain a zero sequence component;
the zero sequence component and the capacitance differential pressure control quantity form the zero sequence modulation quantity.
In one embodiment, the method further comprises:
According to the working electrical parameters, obtaining the initial component of the modulated wave of the Vienna rectifier under a two-phase coordinate system through proportional integral control;
and carrying out three-phase-two-phase inverse transformation on the initial components of the modulated waves in the two-phase coordinate system to obtain the initial components of the modulated waves of each phase in the three-phase coordinate system.
In one embodiment, the determining the switching function of each phase switch according to the duty ratio, and controlling the operation state of the Vienna rectifier through the switching function includes:
Carrying out single-phase carrier PWM control on initial components of each modulated wave under a three-phase coordinate system according to the duty ratio to obtain a switching function of the Vienna rectifier;
and generating a switching signal according to the switching function, wherein the switching signal is used for controlling the on and off of each phase of switch in the Vienna rectifier.
In a second aspect, the present application further provides a control device for a Vienna rectifier, including:
the parameter acquisition module is used for acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced;
The first modulation control module is used for determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation of the Vienna rectifier and the working electrical parameter, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
The second modulation control module is used for obtaining the network side current of the Vienna rectifier, determining the duty ratio of each phase switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
In a third aspect, the present application also provides a computer device comprising a memory and a processor, the memory storing a computer program, the processor implementing the following steps when executing the computer program:
acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced;
Determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
And acquiring network side current of the Vienna rectifier, determining the duty ratio of each phase of switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase of switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
In a fourth aspect, the present application also provides a computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of:
acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced;
Determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
And acquiring network side current of the Vienna rectifier, determining the duty ratio of each phase of switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase of switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
In a fifth aspect, the application also provides a computer program product comprising a computer program which, when executed by a processor, performs the steps of:
acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced;
Determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
And acquiring network side current of the Vienna rectifier, determining the duty ratio of each phase of switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase of switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
The control method, the control device, the computer equipment, the storage medium and the computer program product of the Vienna rectifier are realized by acquiring the working electric parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced; the working electric parameters of the charging equipment under the normal operation working condition can be obtained, and the accuracy of control can be improved by taking the electric parameters under the normal operation working condition as the data base of the control method; determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave; the harmonic wave in the system can be effectively reduced, the voltage fluctuation of the middle point is restrained, the power factor of the charging equipment is improved, and the energy efficiency of the system is improved; the network side current of the Vienna rectifier is obtained, the duty ratio of each phase switch in the Vienna rectifier is determined according to the network side current and the target modulation wave, the switching function of each phase switch is determined according to the duty ratio, the running state of the Vienna rectifier is controlled through the switching function, the output current can be accurately controlled, and the stability and the energy efficiency of the system are improved. According to the method, the midpoint potential balance control and the current feedback are combined in the control process to obtain the modulation wave, so that the point position fluctuation and the emission current distortion of the neutral point of the capacitor at the direct current side can be restrained, and the stability of the charging process and the safety of charging equipment can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.
FIG. 1 is an application environment diagram of a control method of a Vienna rectifier in one embodiment;
FIG. 2 is a circuit diagram of a Vienna rectifier in one embodiment;
FIG. 3 is a flow chart of a control method of the Vienna rectifier in one embodiment;
FIG. 4 is a schematic diagram of a DC side neutral point potential balance control of a control method of a Vienna rectifier according to an embodiment;
FIG. 5 is a schematic diagram of an AC side current feedback control of a control method of a Vienna rectifier in one embodiment;
FIG. 6 is a control schematic diagram of a control method of the Vienna rectifier in one embodiment;
FIG. 7 is a block diagram of a control device of the Vienna rectifier in one embodiment;
fig. 8 is an internal structural diagram of a computer device in one embodiment.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
The control method of the Vienna rectifier provided by the embodiment of the application can be applied to an application environment shown in figure 1. Wherein the terminal 102 communicates with the server 104 via a network. The data storage system may store data that the server 104 needs to process. The data storage system may be integrated on the server 104 or may be located on a cloud or other network server. The terminal 102 may be, but is not limited to, various charging posts, user terminals such as smart phones and tablet computers, personal computers, notebook computers, and the like. The server 104 may be implemented by a stand-alone server or a server cluster formed by a plurality of servers, and may include a background server, a payment gateway server, a data analysis server, an energy management system server, and the like.
With the increasing popularity of electrified traffic throughout the world, electric vehicles and their associated charging facilities are mass-connected to the power grid. The large-scale electric automobile charging cluster is connected with a power grid to bring the electric energy quality problems of three-phase unbalance, voltage loss, harmonic pollution and the like. The harmonic pollution refers to voltage or current waveforms with non-whole period in the power system, the harmonic pollution can cause the increase of internal loss of equipment, the reduction of energy efficiency, even the influence on the normal operation of the equipment, and the increase of energy consumption and resource waste of the power system, so how to alleviate the harmonic pollution in the power system is one of the problems to be solved in the power system. The Vienna rectifier is a three-phase three-level PWM rectifier, the circuit structure of the Vienna rectifier is shown in fig. 2, and the Vienna rectifier comprises three power crystals, can be used for generating sine wave input current and controllable voltage output, and can realize efficient bidirectional power conversion, so that the Vienna rectifier is widely applied to charging equipment such as automobile charging piles. However, the Vienna charging device has the problems of potential fluctuation and emission current distortion of a neutral point of a capacitor at a direct current side, which affects the stability of a charging process and the safety of the charging device, and even causes harmonic pollution in a power grid or affects the normal operation of other power devices.
In an exemplary embodiment, as shown in fig. 3, a control method of a Vienna rectifier is provided, and an application environment of the method in fig. 1 is taken as an example to describe an application environment, which includes the following steps 202 to 206. Wherein the Vienna rectifier is used for charging equipment, which may be an automobile charging stake, the method includes:
Step 202, obtaining an operating electrical parameter of the Vienna rectifier under the condition that the network side voltage is sinusoidal and three phases are balanced.
The working electrical parameters can comprise a network side voltage amplitude phase angle, charging power and a network side inductance value. The network side voltage amplitude phase angle refers to the voltage amplitude and phase angle of the power grid or power supply injected into the Vienna rectifier. The charging power refers to the charging power of the electric automobile. The net side inductance refers to the sum of the inductance values of the Vienna rectifier and the system. Three-phase balancing refers to the same magnitude of voltage and current for each phase in a three-phase power system.
For example, voltage data may be measured and recorded at the connection port of the Vienna rectifier to the grid, and current data may be measured and recorded on the ac side using a sensing device such as a voltage sensor, a current transformer, or an oscilloscope.
And 204, determining the zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave.
The zero sequence modulation quantity refers to a waveform for adjusting neutral point voltage. The initial modulated wave refers to the modulated signal waveform generated when the Vienna rectifier begins to operate. The target modulation wave is a modulation signal waveform outputted by the Vienna rectifier, which is expected to be obtained after adjustment according to a control target.
The method comprises the steps of analyzing and modeling the relation between the median voltage fluctuation and the working electric parameters of the Vienna rectifier to obtain a preset functional relation, taking the median voltage fluctuation and other working electric parameters measured in historical data into a function, calculating the required zero sequence modulation quantity, obtaining a target modulation wave by controlling a modulation wave generation algorithm or directly modifying a modulation signal in a controller, and ensuring the stable operation of the rectifier and the suppression effect of the median voltage fluctuation by monitoring the median voltage fluctuation and the working electric parameters in real time and adjusting the injected zero sequence modulation quantity and modulation waveform according to actual conditions in the operation process of the rectifier.
Step 206, obtaining the network side current of the Vienna rectifier, determining the duty ratio of each phase switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
The grid-side current refers to current received by the rectifier from the power grid. Each phase of switching in the rectifier refers to a power switching device for controlling the rectifier, such as an IGBT (insulated gate bipolar transistor) or a MOSFET (metal oxide semiconductor field effect transistor), a GTO (gate controlled thyristor) or an IGCT (insulated gate double controlled thyristor), for the Vienna rectifier, the power switching device mainly refers to an IGBT. The duty cycle refers to the ratio of the on time of the switching device in one cycle to the total cycle time. Switching functions refer to functions or algorithms that describe the switching states of the phases in the rectifier.
The network side current value can be obtained through measuring equipment such as a current sensor, the duty ratio of each phase of switch is determined according to the current demand and the modulation waveform, a PID controller, a model predictive controller or other control algorithms are adopted to generate a switching function according to the duty ratio and a system control strategy, and then the working state of each phase of switching device in the rectifier is controlled through the controller or the logic circuit.
In the control method of the Vienna rectifier, the working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced are obtained; the working electric parameters of the charging equipment under the normal operation working condition can be obtained, and the accuracy of control can be improved by taking the electric parameters under the normal operation working condition as the data base of the control method; determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation and the working electrical parameter of the Vienna rectifier, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave; the harmonic wave in the system can be effectively reduced, the voltage fluctuation of the middle point is restrained, the power factor of the charging equipment is improved, and the energy efficiency of the system is improved; the network side current of the Vienna rectifier is obtained, the duty ratio of each phase switch in the Vienna rectifier is determined according to the network side current and the target modulation wave, the switching function of each phase switch is determined according to the duty ratio, the running state of the Vienna rectifier is controlled through the switching function, the output current can be accurately controlled, and the stability and the energy efficiency of the system are improved. According to the method, the midpoint potential balance control and the current feedback are combined in the control process to obtain the modulation wave, so that the point position fluctuation and the emission current distortion of the neutral point of the capacitor at the direct current side can be restrained, and the stability of the charging process and the safety of charging equipment can be improved.
In an exemplary embodiment, the method further comprises: acquiring a voltage difference between a first capacitor and a second capacitor of a direct current side of the Vienna rectifier; a capacitance difference control amount for suppressing the neutral point voltage fluctuation of the Vienna rectifier is determined from the voltage difference.
The first capacitor and the second capacitor are two capacitors connected through a neutral point in the Vienna rectifier, and can play a role in voltage division. The capacitance difference control amount refers to a control amount for changing a voltage difference between the first capacitance and the second capacitance.
For example, the voltage difference between the first capacitance and the second capacitance can be determined by historical operating parameters or by simulation calculations, from which the capacitance difference control quantity for suppressing the voltage fluctuations at the point in the Vienna rectifier is determined by a feedback control method.
In one exemplary embodiment, where the grid side voltage is sinusoidal and three phases are balanced, obtaining the operating electrical parameters of the Vienna rectifier includes: acquiring three-phase voltage and three-phase current of a main circuit of the Vienna rectifier; and carrying out three-phase-two-phase conversion on the three-phase voltage and the three-phase current to obtain a main circuit current and a main circuit voltage under a two-phase coordinate system, wherein the main circuit current and the main circuit voltage under the two-phase coordinate system are used as working electric parameters of the Vienna rectifier.
The three-phase-two-phase transformation refers to converting a three-phase current or voltage into two equivalent two-phase currents or voltages. The two-phase coordinate system refers to a coordinate system of two-phase currents or voltages.
For example, the acquired three-phase current or voltage may be park transformed, i.e., the three-phase current or voltage is converted from a stationary ABC coordinate system to a rotating dq coordinate system, thereby converting the time-varying problem to a relatively simple constant coefficient problem to simplify the analysis and calculation process.
In an exemplary embodiment, the amount of zero sequence modulation required to be injected for suppressing the median point voltage ripple of the Vienna rectifier is determined according to a preset functional relationship between the median point voltage ripple and the operating electrical parameter of the Vienna rectifier; comprising the following steps: acquiring a relation function between a zero sequence component of a target modulation wave and a capacitance differential pressure control quantity; solving a relation function by taking eliminating the neutral point voltage fluctuation as a target to obtain a zero sequence component; the zero sequence component and the capacitance differential pressure control quantity form the zero sequence modulation quantity.
The zero sequence component refers to a component which has no symmetry in three-phase voltage or current, and the voltage distribution can be adjusted by introducing the zero sequence component in a control link, so that the voltage fluctuation of the middle point is reduced.
The relation function between the zero-sequence component of the target modulation wave and the capacitance differential pressure control quantity can be obtained through mathematical modeling and the like, the voltage tolerance can be adjusted through the controller by taking the middle-point voltage fluctuation as a feedback signal, so that the middle-point voltage fluctuation is minimized, and the zero-sequence component and the capacitance differential pressure control quantity are directly added to obtain the zero-sequence modulation quantity.
In an exemplary embodiment, the method further comprises: according to the working electrical parameters, obtaining the initial component of the modulated wave of the Vienna rectifier under a two-phase coordinate system through proportional integral control; and carrying out three-phase-two-phase inverse transformation on the initial components of the modulated waves in the two-phase coordinate system to obtain the initial components of the modulated waves of each phase in the three-phase coordinate system.
The proportional-integral control is a control method for generating a control output according to the difference between the magnitude of the error and the reference value and the accumulated amount of the error. The three-phase to two-phase inverse transformation refers to a process of converting three-phase voltages or currents into two-phase voltages or currents, which may be implemented by vector rotation or transformation matrices. The modulated wave initial component refers to a basic waveform used to generate the PWM signal.
For example, a proportional-integral (PI) controller may be designed according to a control objective and system characteristics, and the proportional and integral parameters may be adjusted, so that the proportional term is responsible for generating an output according to the current error magnitude, the integral term is responsible for eliminating a static error, and the output generated by the controller is the initial component of the modulated wave of the Vienna rectifier in the two-phase coordinate system, and the three-phase-two-phase inverse transformation may be implemented by park inverse transformation.
In an exemplary embodiment, the determining the switching function of each phase switch according to the duty cycle, and controlling the operating state of the Vienna rectifier through the switching function includes: carrying out single-phase carrier PWM control on initial components of each modulated wave under a three-phase coordinate system according to the duty ratio to obtain a switching function of the Vienna rectifier; and generating a switching signal according to the switching function, wherein the switching signal is used for controlling the on and off of each phase of switch in the Vienna rectifier.
The single-phase carrier PWM (Pulse Width Modulation) control refers to a signal modulation process of modulating a high-frequency carrier signal into a pulse sequence having a pulse width related to an ac voltage to be controlled.
Illustratively, the PWM signal of each phase may be calculated according to the duty cycle and the modulation wave, the switching signals for controlling the on and off of each switching device in the Vienna rectifier are generated according to the topology structure of the Vienna rectifier according to the obtained PWM signal, and the switching signals generated by the driving circuit are converted into actual switching control signals to control the on and off of the power switching devices.
In an exemplary embodiment, a control method of a Vienna rectifier is provided, including the steps of:
In step 402, the voltage at the dc side of the vienna rectifier fluctuates and the corresponding solution theory derives. Let the voltage of net side be sinusoidal and three-phase balance, then the A phase voltage is:
(1)
Wherein: for the magnitude of the voltage on the net side, Is the power frequency angular frequency,Is the voltage initial phase angle.
When the three-phase output power is P, the power factor is 1 in a steady state, and when the inductance and the resistance are ignored, the initial modulation wave at the moment is:
(2)
Wherein: For the initial modulation of the wave, For the net-measured voltage effective value,In order to modulate the amplitude of the wave,In order to modulate the initial phase angle of the wave,For the purpose of ac-sensing the inductance,Is the charging power.
The state equation on the dc side is:
(3)
in the presence of the mid-site balance control, the latter part of the above equation is negligible, and considering the power factor of the control system is 1, the following expression exists:
(4)
Wherein: Is a capacitor at the direct current side, Is the value of the current at the alternating current side,As a sign function
Solving the differential equation above can result in:
(5)
As can be seen from the expression derived from theory, if the neutral point balance control is added or the control addition is not proper, there is a voltage difference between the upper and lower capacitor voltages on the dc side, that is, there is fluctuation in the mid-point voltage, and the main component of the main fluctuation is three-order components. When there is middle-site voltage fluctuation, the charging effect of the charger, harmonic emission pollution, bearing limitation of devices and the like are affected to different degrees, so that control needs to be set in a targeted manner.
According to the deduction result, the invention proposes to limit the voltage fluctuation of the neutral point by adding the corresponding zero sequence component to the modulated wave and introducing a capacitance differential pressure to assist in control. When adding zero sequence components, there are the following expressions:
(6)
to eliminate midpoint voltage fluctuations, the above expression can be solved to obtain:
(7)
in the invention, the zero sequence modulation quantity is designed as a zero sequence component and a capacitance differential pressure assistance part is introduced, and the zero sequence component is the simplified expression:
(8)
In step 404, a neutral point balance control design. As shown in fig. 4, the charging power is a function of the original modulated wave Modulating wave amplitude M, then passingAdding the voltage fluctuation feedback branch and the modulation wave branch to form a final modulation wave, wherein the final output modulation wave is as follows:
(9)
Each function in the design chart has the expression form:
(10)
(11)
(12)
step 406, self-harmonic current emission and corresponding solution theory derivation. This part is mainly deduced by theory of self-harmonic emission of the main circuit of the rectifier of the Vienna direct current charger, and the control part is designed according to analysis pertinence, so that the current distortion degree of the charger is smaller as much as possible. The relationship between the switching ac side port voltage and the ac side current can be expressed as:
(13)
This expression illustrates that the distortion of the current on the net side depends on the port voltage of the switching device, while the waveform of the port voltage depends on the sign of the current on the net side, the voltage fluctuation of the midpoint, and the modulation wave.
According to the above deduction result, the port voltage of the switching device is made to be sine wave as far as possible by adding the feedback of the net side current sign function on the modulation wave, so that the distortion of the alternating side current is reduced as far as possible. The corresponding modulated wave expression should be:
(14)
according to the steady state condition, the port voltage of the switching device can be obtained as follows:
(15)
the state equation on the net side is:
(16)
in the middle of In order to reduce distortion of the current, the relation between the switching function expression and the modulation wave is as follows:
(17)
Step 408, reducing the circuit feedback design of the emission current. The controller design is performed according to the deduction process and conclusion of the step 406, the design result is shown in fig. 5, the network side current passes through the sign function module based on the modulation wave generated in the step 402 and the step 404, and the modulation wave is combined in the function The duty ratio is formed under the action of the pulse generator, and finally the pulse required by each phase of switch can be output through a pwm link. The expression form of each function in the graph is:
(18)
(19)
at this time, after the sign current is changed based on the original modulation wave, the problem that the angle between the network side current and the port voltage is inconsistent can be reduced, and the distortion degree of the current can be reduced.
Step 410, overall rectifier control flow graph design. The method mainly comprises direct-current side voltage control, current tracking network side voltage control under dq axis, neutral point voltage balance control, current feedback control and PWM modulation links. The implementation of this part is shown in fig. 6: the first part is sampling and park transformation of each part of the main circuit to obtain each electric variable under the dq axis; the second part is direct-current side voltage constant-voltage control and alternating-current side current tracking control, the second part is performed under a dq coordinate system, each part adopts PI control, and the final result obtains the initial components of the modulated waves of each phase through park inverse transformation; the third part is a neutral point balance control part and a network side current feedback part, and finally a switching function is obtained after single-phase carrier PWM control.
The method is based on the realization principle and steps of the control method of the Vienna rectifier of the charger with neutral point potential balance for reducing harmonic emission. The control method of the Vienna rectifier provided by the invention is based on theoretical derivation of midpoint potential fluctuation and self current emission, and is based on the traditional dq control, and the control method of combining midpoint potential balance control and current feedback with modulated waves is added, so that compared with control modes such as SVM (support vector machine), control under a natural coordinate system and the like, the control method better limits the problem of midpoint voltage fluctuation and self harmonic emission in a direct current side, and the control method has more comprehensive consideration of the problem and wider application range.
It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.
Based on the same inventive concept, the embodiment of the application also provides a control device of the Vienna rectifier for realizing the control method of the Vienna rectifier. The implementation of the solution provided by the device is similar to the implementation described in the above method, so the specific limitation in the embodiments of the control device for one or more Vienna rectifiers provided below may be referred to the limitation of the control method for the Vienna rectifier hereinabove, and will not be repeated here.
In an exemplary embodiment, as shown in fig. 7, there is provided a control device of a Vienna rectifier, including: parameter acquisition module, first modulation control module and second modulation control module, wherein:
The parameter acquisition module is used for acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced; the working electrical parameters comprise a network side voltage amplitude phase angle, charging power and a network side inductance value.
The first modulation control module is used for determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation of the Vienna rectifier and the working electrical parameter, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
The second modulation control module is used for obtaining the network side current of the Vienna rectifier, determining the duty ratio of each phase switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
In an exemplary embodiment, the first modulation control module is further configured to: acquiring a voltage difference between a first capacitor and a second capacitor of a direct current side of the Vienna rectifier; a capacitance difference control amount for suppressing the neutral point voltage fluctuation of the Vienna rectifier is determined from the voltage difference.
In an exemplary embodiment, the parameter acquisition module is further configured to: acquiring three-phase voltage and three-phase current of a main circuit of the Vienna rectifier; and carrying out three-phase-two-phase conversion on the three-phase voltage and the three-phase current to obtain a main circuit current and a main circuit voltage under a two-phase coordinate system, wherein the main circuit current and the main circuit voltage under the two-phase coordinate system are used as working electric parameters of the Vienna rectifier.
In an exemplary embodiment, the first modulation control module is further configured to: acquiring a relation function between a zero sequence component of a target modulation wave and a capacitance differential pressure control quantity; solving a relation function by taking eliminating the neutral point voltage fluctuation as a target to obtain a zero sequence component; the zero sequence component and the capacitance differential pressure control quantity form the zero sequence modulation quantity.
In one exemplary embodiment, in one of the embodiments, the second modulation control module is further configured to: according to the working electrical parameters, obtaining the initial component of the modulated wave of the Vienna rectifier under a two-phase coordinate system through proportional integral control; and carrying out three-phase-two-phase inverse transformation on the initial components of the modulated waves in the two-phase coordinate system to obtain the initial components of the modulated waves of each phase in the three-phase coordinate system.
In an exemplary embodiment, the second modulation control module is further configured to: carrying out single-phase carrier PWM control on initial components of each modulated wave under a three-phase coordinate system according to the duty ratio to obtain a switching function of the Vienna rectifier; and generating a switching signal according to the switching function, wherein the switching signal is used for controlling the on and off of each phase of switch in the Vienna rectifier.
The respective modules in the control device of the Vienna rectifier described above may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one exemplary embodiment, a computer device is provided, which may be a server, and the internal structure thereof may be as shown in fig. 8. The computer device includes a processor, a memory, an Input/Output interface (I/O) and a communication interface. The processor, the memory and the input/output interface are connected through a system bus, and the communication interface is connected to the system bus through the input/output interface. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The database of the computer device is used for storing various data and working parameters involved in the charging control process or the Vienna rectifier control process, such as current, voltage, power, charging state, fault diagnosis information and the like. The input/output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of controlling a Vienna rectifier.
It will be appreciated by those skilled in the art that the structure shown in FIG. 8 is merely a block diagram of some of the structures associated with the present inventive arrangements and is not limiting of the computer device to which the present inventive arrangements may be applied, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.
In one embodiment, a computer device is provided, comprising a memory and a processor, the memory having stored therein a computer program, the processor implementing the steps of the method embodiments described above when the computer program is executed. The computer device may be a computer device as shown in fig. 8.
In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored which, when executed by a processor, implements the steps of the method embodiments described above.
In an embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the steps of the method embodiments described above.
It should be noted that, the user information (including but not limited to user equipment information, user personal information, etc.) and the data (including but not limited to data for analysis, stored data, presented data, etc.) related to the present application are both information and data authorized by the user or sufficiently authorized by each party, and the collection, use and processing of the related data are required to meet the related regulations.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magneto-resistive random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (Ferroelectric Random Access Memory, FRAM), phase change Memory (PHASE CHANGE Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in various forms such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), etc. The databases referred to in the embodiments provided herein may include at least one of a relational database and a non-relational database. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processor referred to in the embodiments provided in the present application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, or the like, but is not limited thereto.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the application and are described in detail herein without thereby limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of the application should be assessed as that of the appended claims.
Claims (10)
1. A control method of a Vienna rectifier for a charging device, the method comprising:
Acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced; the working electrical parameters comprise a network side voltage amplitude phase angle, charging power and a network side inductance value;
Determining a zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation of the Vienna rectifier and the working electrical parameter, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
And acquiring a network side current of the Vienna rectifier, determining the duty ratio of each phase switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
2. The method according to claim 1, wherein the method further comprises:
Acquiring a voltage difference between a first capacitor and a second capacitor of a direct current side of the Vienna rectifier;
And determining a capacitance differential pressure control quantity for inhibiting the neutral point voltage fluctuation of the Vienna rectifier according to the voltage difference.
3. The method according to claim 1, wherein the obtaining the operating electrical parameters of the Vienna rectifier in case the grid-side voltage is sinusoidal and three-phase balanced comprises:
acquiring three-phase voltage and three-phase current of a main circuit of the Vienna rectifier;
And carrying out three-phase-two-phase conversion on the three-phase voltage and the three-phase current to obtain a main circuit current and a main circuit voltage under a two-phase coordinate system, wherein the main circuit current and the main circuit voltage under the two-phase coordinate system are used as working electric parameters of the Vienna rectifier.
4. The method according to claim 2, characterized in that the amount of zero sequence modulation to be injected for suppressing the median point voltage ripple of the Vienna rectifier is determined from a preset functional relation between the median point voltage ripple of the Vienna rectifier and the operating electrical parameter; comprising the following steps:
acquiring a relation function between the zero sequence component of the target modulation wave and the capacitance differential pressure control quantity;
solving the relation function by taking eliminating the neutral point voltage fluctuation as a target to obtain the zero sequence component;
And the zero sequence component and the capacitance differential pressure control quantity form the zero sequence modulation quantity.
5. The method according to claim 1, wherein the method further comprises:
According to the working electrical parameters, obtaining the initial component of the modulated wave of the Vienna rectifier under a two-phase coordinate system through proportional integral control;
and carrying out three-phase-two-phase inverse transformation on the initial components of the modulated waves under the two-phase coordinate system to obtain the initial components of the modulated waves of each phase under the three-phase coordinate system.
6. The method of claim 1, wherein said determining a switching function of the phase switches as a function of the duty cycle, the operating state of the Vienna rectifier being controlled by the switching function, comprises:
Carrying out single-phase carrier PWM control on initial components of each modulated wave under a three-phase coordinate system according to the duty ratio to obtain a switching function of the Vienna rectifier;
and generating a switching signal according to the switching function, wherein the switching signal is used for controlling the on and off of each phase of switch in the Vienna rectifier.
7. A control apparatus of a Vienna rectifier for a charging device, the apparatus comprising:
The parameter acquisition module is used for acquiring working electrical parameters of the Vienna rectifier under the conditions that the network side voltage is sinusoidal and three phases are balanced; the working electrical parameters comprise a network side voltage amplitude phase angle, charging power and a network side inductance value;
The first modulation control module is used for determining zero sequence modulation quantity required to be injected for inhibiting the median voltage fluctuation of the Vienna rectifier according to a preset functional relation between the median voltage fluctuation of the Vienna rectifier and the working electrical parameter, and injecting the zero sequence modulation quantity into an initial modulation wave of the Vienna rectifier to obtain a target modulation wave;
The second modulation control module is used for obtaining the network side current of the Vienna rectifier, determining the duty ratio of each phase switch in the Vienna rectifier according to the network side current and the target modulation wave, determining the switching function of each phase switch according to the duty ratio, and controlling the running state of the Vienna rectifier through the switching function.
8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 6 when the computer program is executed.
9. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 6.
10. A computer program product comprising a computer program, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 6.
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