CN117294114A - Three-phase four-wire PWM rectifier control method, device, equipment and storage medium - Google Patents
Three-phase four-wire PWM rectifier control method, device, equipment and storage medium Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
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Abstract
The invention relates to a control method, a device, equipment and a storage medium of a three-phase four-wire PWM rectifier, wherein the method comprises the following steps: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter; determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop; and setting an initial offset, inputting the initial offset and the current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier. The invention firstly determines the current reference value by controlling the designed voltage outer ring, then determines the current difference value according to the current reference value and the alternating-current side inductance current based on the designed current inner ring, then sets the initial offset to determine the current offset value, and finally can regulate the alternating-current side inductance current and the output voltage of the three-phase four-wire PWM rectifier by only one PID controller, thereby having simple control algorithm and simple analysis process and being suitable for engineering practice.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a control method, a control device, control equipment and a storage medium of a three-phase four-wire PWM rectifier.
Background
The three-phase PWM rectifier is a common power electronic device, and compared with the three-phase three-wire PWM rectifier, the three-phase four-wire PWM rectifier can better inhibit the direct current component of the input current, greatly improve the waveform quality of the input current, and further improve the power factor of the rectifier, so that the three-phase four-wire PWM rectifier is more and more put into use.
At present, there are many control strategies for a three-phase four-wire PWM rectifier, such as single-cycle control, zero static difference control of input current by using a virtual orthogonal transformation method, suppression of network side current harmonic wave by using fractional order repetitive control, and the like. These control strategies typically require two PID controllers, even three PID controllers, to accomplish control, which can yield good control results for some aspect of the PWM rectifier.
However, the control strategy of the current three-phase four-wire PWM rectifier needs to be completed by a plurality of PID controllers, the control algorithm is complex, the analysis process is complex, the three-phase four-wire PWM rectifier cannot be controlled in time, and engineering practice is not facilitated.
Disclosure of Invention
In view of the foregoing, it is necessary to provide a control method, apparatus, device and storage medium for a three-phase four-wire PWM rectifier, so as to solve the problems in the prior art that the control of the three-phase four-wire PWM rectifier is completed by a plurality of PID controllers, resulting in complex control algorithm and complex analysis process, and the three-phase four-wire PWM rectifier cannot be controlled in time, which is not beneficial to engineering practice.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a three-phase four-wire PWM rectifier control method, including:
determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter;
determining a current difference value according to an alternating-current side inductance current of the three-phase four-wire PWM rectifier and a current reference value based on the current inner loop;
and setting an initial offset, inputting the initial offset and a current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier.
In some possible implementations, determining the current reference value from the output voltage of the three-phase four-wire PWM rectifier based on the voltage outer loop includes:
generating a duty ratio wave table according to the duty ratio expression and the initial value of an automatic loading register of the singlechip timer;
setting a phase offset, and determining a current standard value according to the phase offset and a duty ratio wave table;
and carrying out step-by-step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine a current reference value.
In some possible implementations, generating the duty cycle wave table from the duty cycle expression and an initial value of an auto-load register of the singlechip timer includes:
the duty cycle expression is:
wherein D is a duty ratio value, N is the number of values in the wave table, k is a specific value from 0 to N, and m is a modulation degree;
determining a wave table median value according to an initial value of an automatic loading register of the singlechip timer;
and generating a duty ratio wave table according to the wave table median value and the duty ratio expression.
In some possible implementations, determining the current standard value from the phase offset and the duty cycle wave table includes:
judging the half cycle of the phase voltage;
determining a wave table index value according to the half cycle where the phase voltage is and the duty ratio wave table;
and determining a current standard value according to the wave table index value and the phase offset.
In some possible implementations, step-wise adjustment of the output voltage to determine the current reference value based on the wavetable coefficient and the current reference value includes:
setting an initial wave table coefficient;
if the initial wave table coefficient does not meet the preset condition, the initial wave table coefficient is adjusted until the output voltage meets the preset voltage reference value, and a target wave table coefficient is obtained;
and multiplying the target wavetable coefficient by a current standard value to obtain a current reference value.
In some possible implementations, inputting the initial offset and the current difference to the PID controller to calculate the duty cycle to control the three-phase four-wire PWM rectifier includes:
determining a plurality of continuous current bias values according to the initial bias amount and the current difference value;
calculating a duty ratio according to a plurality of current bias values after the discrete expression based on the PID controller;
the alternating current side inductor current and the output voltage of the three-phase four-wire PWM rectifier are regulated according to the duty ratio.
In some possible implementations, the discrete expression of the PID controller is as follows:
Δu(k)＝K p [e r (k)-e r (k-1)]+K i e r (k)+K d [e r (k)-2e r (k-1)+e r (k-2)]；
wherein Deltau (K) represents the duty cycle of the controller output, K p 、K i 、K d Gain coefficients, e, representing the ratio, integral and derivative, respectively r (k)，e r (k-1)、e r (k-2) represents the current bias value of the kth time, the current bias value of the kth-1 time, and the current bias value of the kth-2 time, respectively.
In a second aspect, the present invention also provides a three-phase four-wire PWM rectifier control apparatus, including:
the voltage loop module is used for determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter;
the current loop module is used for determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and a current reference value based on the current inner loop;
and the control module is used for setting the initial offset, inputting the initial offset and the current difference value into the PID controller, calculating the duty ratio and controlling the three-phase four-wire PWM rectifier.
In a third aspect, the present invention also provides a three-phase four-wire PWM rectifier control apparatus comprising a memory and a processor, wherein,
a memory for storing a program;
and a processor coupled to the memory for executing the program stored in the memory to implement the steps in the three-phase four-wire PWM rectifier control method in any one of the above implementations.
In a fourth aspect, the present invention also provides a computer readable storage medium storing a computer readable program or instructions which, when executed by a processor, enable the implementation of the steps in the three-phase four-wire PWM rectifier control method in any one of the above implementations.
The beneficial effects of adopting the embodiment are as follows: the invention relates to a control method, a device, equipment and a storage medium of a three-phase four-wire PWM rectifier, wherein the method comprises the following steps: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter; determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop; and setting an initial offset, inputting the initial offset and the current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier. The invention firstly determines the current reference value by controlling the designed voltage outer ring, then determines the current difference value according to the current reference value and the alternating current side inductance current based on the designed current inner ring, then determines the current bias value by setting the initial bias value, and finally can realize the adjustment of the alternating current side inductance current and the output voltage of the three-phase four-wire PWM rectifier by only one PID controller by sequentially controlling the voltage outer ring and the double rings of the current inner ring, thereby reducing the number of the PID controllers, leading the control algorithm to be simpler and the analysis process to be simpler, and being better put into engineering practice.
Drawings
FIG. 1 is a schematic flow chart of a control method of a three-phase four-wire PWM rectifier according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a three-phase four-wire PWM rectifier control system according to an embodiment of the present invention;
FIG. 3 is a flowchart illustrating an embodiment of the step S101 in FIG. 1 according to the present invention;
FIG. 4 is a schematic diagram illustrating a portion of an embodiment of a duty cycle wave table according to the present invention;
FIG. 5 is a flowchart illustrating an embodiment of step S202 in FIG. 2 according to the present invention;
fig. 6 is a flowchart illustrating an embodiment of step S203 in fig. 2 according to the present invention;
FIG. 7 is a schematic flow chart diagram illustrating an embodiment of controlling a three-phase four-wire PWM rectifier according to the present invention;
fig. 8 is a schematic structural diagram of an embodiment of a three-phase four-wire PWM rectifier bridge control apparatus according to the present invention;
fig. 9 is a schematic structural diagram of a three-phase four-wire PWM rectifier control apparatus according to an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and together with the description serve to explain the principles of the invention, and are not intended to limit the scope of the invention.
In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
The invention provides a control method, a control device, control equipment and a storage medium of a three-phase four-wire PWM rectifier, which are respectively described below.
Referring to fig. 1, fig. 1 is a flow chart of an embodiment of a control method of a three-phase four-wire PWM rectifier according to the present invention, and a control method of a three-phase four-wire PWM rectifier is disclosed, which includes:
s101, determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter;
s102, determining a current difference value according to an alternating-current side inductance current and a current reference value of a three-phase four-wire PWM rectifier based on a current inner loop;
s103, setting initial offset, inputting the initial offset and a current difference value into a PID controller, calculating duty ratio and controlling the three-phase four-wire PWM rectifier.
In the above embodiment, the three-phase four-wire PWM rectifier is used as a unified circuit, and the control of the three-phase four-wire PWM rectifier needs to be implemented in an overall control system, referring to fig. 2, fig. 2 is a schematic structural diagram of an embodiment of the control system of the three-phase four-wire PWM rectifier provided by the present invention, and the output voltage of the three-phase four-wire PWM rectifier first passes through the voltage outer loop, and is compared with a preset reference voltage and is adjusted, so that the output voltage gradually approaches the preset reference voltage, and the effect of tracking the reference voltage by the output voltage is achieved, where the current corresponding to the output voltage is the current reference value.
It should be noted that, the circuit in which the output voltage of the three-phase four-wire PWM rectifier in fig. 2 is compared with the voltage reference value through the filter to obtain the variable voltage, and then the current reference value is obtained through the voltage regulator is the voltage outer loop, the ac side inductor current of the three-phase four-wire PWM rectifier in fig. 2 is compared with the current reference value through the filter, and the circuit reaching the discrete PID controller through the overcurrent protection is the current inner loop.
The current inner loop can control the inductance current of the alternating current side, keep the inductance current of the alternating current side constant, control the inductance current of the alternating current side of the three-phase four-wire PWM rectifier according to the current reference value output by the voltage outer loop, determine the current difference between the inductance current of the alternating current side and the current reference value, and transmit the difference as input to the PID controller.
The initial offset can be adjusted later, and is input to the PID controller through the capacitor voltage equalizer to control the current difference and the offset, and the duty ratio of the three-phase four-wire PWM rectifier is adjusted, so that the output voltage of the three-phase four-wire PWM rectifier and the inductance current of the alternating current side are controlled, the actual inductance current of the alternating current side is controlled along with the current reference value in the wave table, and the input current is sinusoidal.
It should be noted that, because the three-phase four-wire PWM rectifier has multiple phases, in order to control the three-phase four-wire PWM rectifier, a single phase needs to be controlled, so the invention needs to determine the relationship between phases by constructing an average equivalent model of the three-phase four-wire PWM rectifier, determine the relationship between the bridge arm voltage and the dc side voltage according to the topology structure and the switching mode of the three-phase four-wire PWM rectifier, further determine the state equation of the three-phase four-wire PWM rectifier and the average duty ratio of three bridge arms, and further derive the average equivalent model of the three-phase four-wire PWM rectifier according to the switching cycle average method, thereby determining that each phase of the three-phase four-wire PWM rectifier circuit is independent from each other, and there is no coupling relationship between each phase and the three independent one-way full bridge rectifier can be decomposed into three independent one-way full bridge rectifiers.
It will be appreciated that the preset reference voltage and the initial bias amount can be adjusted according to the actual use requirement, and the invention is not limited thereto. As a preferred embodiment, the initial offset is set to be about constant (200 a) by man, and then the PID controller can adjust on the basis during operation to reduce the voltage difference between the upper pipe and the lower pipe.
Compared with the prior art, the control method of the three-phase four-wire PWM rectifier provided by the embodiment comprises the following steps: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter; determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop; and setting an initial offset, inputting the initial offset and the current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier. The invention firstly determines the current reference value by controlling the designed voltage outer ring, then determines the current difference value according to the current reference value and the alternating current side inductance current based on the designed current inner ring, then determines the current bias value by setting the initial bias value, and finally can realize the adjustment of the alternating current side inductance current and the output voltage of the three-phase four-wire PWM rectifier by only one PID controller by sequentially controlling the voltage outer ring and the double rings of the current inner ring, thereby reducing the number of the PID controllers, leading the control algorithm to be simpler and the analysis process to be simpler, and being better put into engineering practice.
In order to achieve accurate control of the three-phase four-wire PWM rectifier, the first step of control is performed by designing the voltage outer loop, referring to fig. 3, fig. 3 is a schematic flow chart of an embodiment of step S101 in fig. 1 provided in the present invention, in some embodiments of the present invention, determining the current reference value according to the output voltage of the three-phase four-wire PWM rectifier based on the voltage outer loop includes:
s301, generating a duty ratio wave table according to a duty ratio expression and an initial value of an automatic loading register of a singlechip timer;
s302, setting a phase offset, and determining a current standard value according to the phase offset and a duty ratio wave table;
s303, carrying out step-by-step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine a current reference value.
In the above embodiment, firstly, the initial value of the automatic loading register of the singlechip timer is set, the initial value of the automatic loading register of the singlechip timer is related to the duty ratio, the duty ratio wave table can be determined through the initial value of the automatic loading register of the singlechip timer, the adjustment of the current reference value output by the voltage outer ring is realized, and the control of the subsequent current inner ring is facilitated.
The Phase offset Phase means that currents with different phases have certain deviation, and an accurate current standard value is determined through the set Phase offset Phase, so that the adjustment control of the voltage outer loop is facilitated, and a current reference value is accurately determined. It will be appreciated that the Phase offset Phase may be adjusted according to the actual situation, and the present invention is not limited thereto, and as a preferred embodiment, the value of the Phase offset Phase is initially set to 0, and may be adjusted according to the requirement of the power factor.
The wave meter coefficient also needs to be set with an initial value in advance, the stepping adjustment of the voltage outer ring can be performed in advance through multiplication of the wave meter coefficient and the current standard value, the output voltage of the three-phase four-wire PWM rectifier gradually approaches to the preset reference voltage through subsequent adjustment of the wave meter coefficient, and the current reference value is output by the final voltage outer ring.
In some embodiments of the present invention, generating a duty cycle wave table from a duty cycle expression and an initial value of an auto-load register of a singlechip timer includes:
the duty cycle expression is:
wherein D is a duty ratio value, N is the number of values in the wave table, k is a specific value from 0 to N, and m is a modulation degree;
determining a wave table median value according to an initial value of an automatic loading register of the singlechip timer;
and generating a duty ratio wave table according to the wave table median value and the duty ratio expression.
In the above embodiment, the SPWM wave duty ratio expression is derived according to the symmetric rule sampling method, in this embodiment, please refer to fig. 4, fig. 4 is a partial schematic diagram of an embodiment of the duty ratio wave table provided by the present invention, and an initial value of an auto-load register of the singlechip timer is set to 4000 (i.e. the duty ratio corresponding to the moment when the value of the wave table is 4000 is 1). However, in the initial adjustment, a margin for up-and-down adjustment is reserved, the invention takes the register values corresponding to the median value and the peak value of the duty ratio to be about 2000, and then a duty ratio wave table containing a certain number of switching devices can be generated through the duty ratio expression (the generation number of the invention is 400 and can be set according to the precision requirement).
Referring to fig. 5, fig. 5 is a flowchart of an embodiment of step S202 in fig. 2, where in some embodiments of the present invention, determining a current standard value according to a phase offset and a duty cycle table includes:
s501, judging the half cycle of the phase voltage;
s502, determining a wave table index value according to a half cycle and a duty ratio wave table where the phase voltage is located;
s503, determining a current standard value according to the wave table index value and the phase offset.
In the above embodiment, the phase voltage is divided into a positive half cycle and a negative half cycle, a zero crossing detection circuit is set first, the zero crossing detection circuit is connected with the I/O interface of the singlechip, and a timer is set to interrupt into a rising/falling edge trigger mode. The difference between the positive and negative half cycles of the phase voltage affects the determined current standard value.
In the invention, the phase voltage is taken as an example of the positive half cycle, and the following index value of the wave table is obtained when the singlechip detects the falling edge, namely the alternating voltage is about to be in the positive half cycle:
wherein i is u_index 、i v_index 、i w_index The wave table index values respectively representing different three-phase currents.
In order to realize the Phase shift of the current at the alternating side and generate the Phase difference between the alternating voltage and the current so as to adjust the power factor of the rectifier, the invention adds the Phase offset value Phase (the initial Phase value is set to be 0 and can be adjusted according to the requirement of the power factor) after the three-Phase index value at the same time of zero crossing, namely, when the alternating voltage is about to be in the positive half cycle, the invention comprises the following steps:
and obtaining a current standard value.
Referring to fig. 6, fig. 6 is a flowchart of an embodiment of step S203 in fig. 2 provided by the present invention, in some embodiments of the present invention, step-by-step adjustment is performed on an output voltage according to a wavetable coefficient and a current standard value to determine a current reference value, including:
s601, setting an initial wave table coefficient;
s602, if the initial wave table coefficient does not meet the preset condition, adjusting the initial wave table coefficient until the output voltage meets the preset voltage reference value, and obtaining a target wave table coefficient;
s603, multiplying the target wave table coefficient by a current standard value to obtain a current reference value.
In the above embodiment, the present invention uses the introduced wave table coefficient M multiplied by the current reference value, that is, the current reference value is obtained by multiplying the current standard value by M to realize the step adjustment of the voltage. The specific method is as follows: the direct-current side output voltage of the three-phase four-wire PWM rectifier is collected through a direct memory access mode of the ADC, the result is compared with a reference value after digital filtering, if the actual voltage is larger than the reference value, the value of M is reduced, otherwise, the value of M is increased, and after continuous step adjustment, the final output voltage can be stabilized near the reference value, namely DeltaU approaches to 0.
Referring to fig. 7, fig. 7 is a schematic flow chart of an embodiment of controlling a three-phase four-wire PWM rectifier according to the present invention, in some embodiments of the present invention, the method for controlling the three-phase four-wire PWM rectifier by inputting initial offset and current difference values to a PID controller to calculate duty ratio includes:
s701, determining a plurality of continuous current bias values according to the initial bias amount and the current difference value;
s702, calculating the duty ratio according to a plurality of current bias values after discrete expression based on the PID controller;
and S703, adjusting the alternating-current side inductance current and the output voltage of the three-phase four-wire PWM rectifier according to the duty ratio.
In some embodiments of the invention, the discrete expression of the PID controller is as follows:
Δu(k)＝K p [e r (k)-e r (k-1)]+K i e r (k)+K d [e r (k)-2e r (k-1)+e r (k-2)]；
wherein Deltau (K) represents the duty cycle of the controller output, K p 、K i 、K d Gain coefficients, e, representing the ratio, integral and derivative, respectively r (k)，e r (k-1)、e r (k-2) represents the current bias value of the kth time, the current bias value of the kth-1 time, and the current bias value of the kth-2 time, respectively.
In the above embodiment, in order to implement the DC-side capacitor voltage equalization control, the offset dc_bias is added to the input end of the PID controller, that is, the input of the PID controller is:
e r (k)＝I ADC (k)-I ref (k)+DC_Bias；
wherein I is ADC (k) Representing the alternating current side inductor current of the kth three-phase four-wire PWM rectifier currently acquired by the ADC, I ref (k) Representing the kth current reference value of the voltage outer loop output.
The PID controller carries out adjustment control according to the register, outputs the increment of the duty ratio which needs to be set at the time, and realizes the current reference value calculated by the actual alternating-current side inductance current following the voltage outer ring, thereby realizing the input current sinusoidal.
The singlechip detects the total voltage of the direct current side and the lower tube capacitor voltage of the three-phase four-wire PWM rectifier, if the total voltage is more than twice the lower tube voltage, the offset DC_bias is increased, and otherwise, the offset DC_bias is reduced. Because the direct current component of the current on the neutral line is equal to the sum of the direct current components of the three-phase currents and the difference between the direct current components of the upper group of capacitance currents and the lower group of capacitance currents, the difference between the capacitance voltages of the upper tube and the lower tube can be adjusted by simultaneously increasing or decreasing the direct current components of the three-phase four-wire PWM rectifier, thereby realizing the control of the three-phase four-wire PWM rectifier. It should be noted that, the PID controller in this embodiment is an incremental discrete PID controller.
In order to better implement the three-phase four-wire PWM bridge control method according to the embodiment of the present invention, referring to fig. 8, fig. 8 is a schematic structural diagram of an embodiment of a three-phase four-wire PWM bridge control device provided by the present invention, where the three-phase four-wire PWM bridge control device 800 includes:
the voltage loop module 810 is configured to determine a current reference value according to an output voltage of the three-phase four-wire PWM rectifier and a voltage outer loop parameter;
a current loop module 820 for determining a current difference from the ac side inductor current of the three-phase four-wire PWM rectifier and a current reference value based on the current inner loop;
and the control module 830 is configured to set an initial offset, and input the initial offset and a current difference value to the PID controller to calculate a duty ratio to control the three-phase four-wire PWM rectifier.
What needs to be explained here is: the device 800 provided in the foregoing embodiments may implement the technical solutions described in the foregoing method embodiments, and the specific implementation principles of the foregoing modules or units may be referred to the corresponding content in the foregoing method embodiments, which is not described herein again.
Referring to fig. 9, fig. 9 is a schematic structural diagram of a three-phase four-wire PWM rectifier control apparatus according to an embodiment of the present invention. Based on the three-phase four-wire PWM rectifier bridge control method, the invention also correspondingly provides three-phase four-wire PWM rectifier bridge control equipment which can be computing equipment such as a mobile terminal, a desktop computer, a notebook computer, a palm computer, a server and the like. The three-phase four-wire PWM rectifier bridge control apparatus includes a processor 910, a memory 920, and a display 930. Fig. 9 shows only a portion of the components of the three-phase four-wire PWM rectifier control apparatus, but it should be understood that not all of the illustrated components need be implemented and that more or fewer components may alternatively be implemented.
Memory 920 may be an internal storage unit of a three-phase four-wire PWM rectifier bridge control device in some embodiments, such as a hard disk or memory of the three-phase four-wire PWM rectifier bridge control device. The memory 920 may also be an external storage device of the three-phase four-wire PWM bridge control device in other embodiments, for example, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash Card (Flash Card) or the like, which are provided on the three-phase four-wire PWM bridge control device. Further, the memory 920 may also include both internal memory units and external memory devices of the three-phase four-wire PWM rectifier bridge control device. The memory 920 is used for storing application software installed on the three-phase four-wire PWM rectifier bridge control apparatus and various data, such as program codes for installing the three-phase four-wire PWM rectifier bridge control apparatus. Memory 920 may also be used to temporarily store data that has been output or is to be output. In one embodiment, the memory 920 stores a three-phase four-wire PWM bridge control program 940, where the three-phase four-wire PWM bridge control program 940 is executable by the processor 910 to implement the three-phase four-wire PWM bridge control method according to embodiments of the present application.
The processor 910 may be, in some embodiments, a central processing unit (Central Processing Unit, CPU), microprocessor or other data processing chip for executing program code or processing data stored in the memory 920, for example, performing three-phase four-wire PWM bridge control methods, etc.
The display 930 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch, or the like in some embodiments. The display 930 is used to display information at the three-phase four-wire PWM bridge control device and to display a visual user interface. The components 910-930 of the three-phase four-wire PWM bridge control apparatus communicate with each other via a system bus.
In one embodiment, the steps in the three-phase four-wire PWM bridge control method described above are implemented when the processor 910 executes the three-phase four-wire PWM bridge control program 940 in the memory 920.
The present embodiment also provides a computer-readable storage medium having stored thereon a three-phase four-wire PWM bridge control program which, when executed by a processor, performs the steps of:
determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter;
determining a current difference value according to an alternating-current side inductance current of the three-phase four-wire PWM rectifier and a current reference value based on the current inner loop;
and setting an initial offset, inputting the initial offset and a current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier.
In summary, the present embodiment provides a method, an apparatus, a device and a storage medium for controlling a three-phase four-wire PWM rectifier, where the method includes: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter; determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop; and setting an initial offset, inputting the initial offset and the current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier. The invention firstly determines the current reference value by controlling the designed voltage outer ring, then determines the current difference value according to the current reference value and the alternating current side inductance current based on the designed current inner ring, then determines the current bias value by setting the initial bias value, and finally can realize the adjustment of the alternating current side inductance current and the output voltage of the three-phase four-wire PWM rectifier by only one PID controller by sequentially controlling the voltage outer ring and the double rings of the current inner ring, thereby reducing the number of the PID controllers, leading the control algorithm to be simpler and the analysis process to be simpler, and being better put into engineering practice.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. A three-phase four-wire PWM rectifier control method, comprising:
determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter;
determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop;
and setting an initial offset, inputting the initial offset and the current difference value into a PID controller, calculating a duty ratio, and controlling the three-phase four-wire PWM rectifier.
2. The control method of the three-phase four-wire PWM rectifier according to claim 1, wherein the determining the current reference value from the output voltage of the three-phase four-wire PWM rectifier based on the voltage outer loop includes:
generating a duty ratio wave table according to the duty ratio expression and the initial value of an automatic loading register of the singlechip timer;
setting a phase offset, and determining a current standard value according to the phase offset and the duty ratio wave table;
and carrying out step-by-step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine the current reference value.
3. The control method of the three-phase four-wire PWM rectifier according to claim 2, wherein the generating the duty wave table according to the duty expression and the initial value of the auto-load register of the one-chip timer includes:
the duty cycle expression is:
wherein D is a duty ratio value, N is the number of values in the wave table, k is a specific value from 0 to N, and m is a modulation degree;
determining a wave table median value according to an initial value of an automatic loading register of the singlechip timer;
and generating a duty ratio wave table according to the wave table median value and the duty ratio expression.
4. The control method of the three-phase four-wire PWM rectifier according to claim 2, wherein said determining a current standard value from the phase offset and the duty cycle wave table includes:
judging the half cycle of the phase voltage;
determining a wave table index value according to the half cycle of the phase voltage and the duty ratio wave table;
and determining a current standard value according to the wave table index value and the phase offset.
5. The method of claim 2, wherein the step-wise adjusting the output voltage according to the wave form coefficient and the current standard value to determine the current reference value comprises:
setting an initial wave table coefficient;
if the initial wave table coefficient does not meet the preset condition, the initial wave table coefficient is adjusted until the output voltage meets the preset voltage reference value, and a target wave table coefficient is obtained;
and multiplying the target wavetable coefficient by the current standard value to obtain a current reference value.
6. The control method of the three-phase four-wire PWM rectifier according to claim 1, wherein said inputting the initial offset and the current difference to a PID controller to calculate a duty cycle to control the three-phase four-wire PWM rectifier comprises:
determining a plurality of consecutive current bias values from the initial bias amount and the current difference value;
calculating a duty cycle from the plurality of current bias values based on a discrete expression of the PID controller;
and adjusting the inductance current and the output voltage of the alternating-current side of the three-phase four-wire PWM rectifier according to the duty ratio.
7. The method of claim 6, wherein the discrete expression of the PID controller is as follows:
Δu(k)＝K p [e r (k)-e r (k-1)]+K i e r (k)+K d [e r (k)-2e r (k-1)+e r (k-2)]；
wherein Deltau (K) represents the duty cycle of the controller output, K p 、K i 、K d Gain coefficients, e, representing the ratio, integral and derivative, respectively r (k)，e r (k-1)、e r (k-2) represents the current bias value of the kth time, the current bias value of the kth-1 time, and the current bias value of the kth-2 time, respectively.
8. A three-phase four-wire PWM rectifier control apparatus, comprising:
the voltage loop module is used for determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter;
the current loop module is used for determining a current difference value according to the alternating-current side inductance current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop circuit;
and the control module is used for setting initial offset, inputting the initial offset and the current difference value into a PID controller, calculating duty ratio and controlling the three-phase four-wire PWM rectifier.
9. A three-phase four-wire PWM rectifier control device is characterized by comprising a memory and a processor, wherein,
the memory is used for storing programs;
the processor, coupled to the memory, is configured to execute the program stored in the memory to implement the steps in the three-phase four-wire PWM rectifier control method according to any one of claims 1 to 7.
10. A computer readable storage medium storing a computer readable program or instructions which, when executed by a processor, is capable of carrying out the steps of the three-phase four-wire PWM rectifier control method according to any one of claims 1 to 7.
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