CN117394673B - PFC control method and system for inhibiting voltage and current resonance of weak current network - Google Patents

PFC control method and system for inhibiting voltage and current resonance of weak current network Download PDF

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Publication number
CN117394673B
CN117394673B CN202311232566.2A CN202311232566A CN117394673B CN 117394673 B CN117394673 B CN 117394673B CN 202311232566 A CN202311232566 A CN 202311232566A CN 117394673 B CN117394673 B CN 117394673B
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pfc
voltage
current
variable frequency
weak
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CN117394673A (en
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曹成
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Zhuhai Wellgo Inverter Technology Co ltd
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Zhuhai Wellgo Inverter Technology Co ltd
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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4241—Arrangements for improving power factor of AC input using a resonant converter
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
    • 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
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

The invention discloses a PFC control method and system for inhibiting voltage-current resonance of a weak current network, comprising the following steps: the PFC control circuit of the variable frequency driver under the weak current network is controlled by adopting input voltage feedforward, PFC inductance current is used as the feedback quantity of the controller, and meanwhile, the PFC inductance current is used as the input quantity of the harmonic suppression controller and is output and fed back to the PWM controller; the current and voltage resonance under a weak current network is restrained by controlling the duty ratio of a power semiconductor switch controlled by PFC; the PFC control circuit of the variable frequency driver under the weak current network comprises: the power supply circuit comprises an equivalent resistor, an equivalent inductor, an equivalent filter capacitor of a variable frequency drive filter, a rectifier bridge, a variable frequency drive PFC inductor, a follow current diode of PFC, a PFC-controlled power semiconductor switch, a direct current bus capacitor and a variable frequency drive inverter bridge; the invention is used for solving the problem that the existing variable frequency drive of the air conditioner with PFC control is easy to generate resonance under a weak current network.

Description

PFC control method and system for inhibiting voltage and current resonance of weak current network
Technical Field
The invention relates to the technical field of variable frequency drives of air conditioners, in particular to a PFC control method and system for inhibiting voltage and current resonance of a weak current network.
Background
Compared with a fixed-frequency air conditioner, the variable-frequency air conditioner can perform frequency adjustment according to room temperature change, further achieve power adjustment, achieve continuous low-speed running state, avoid frequent starting of a compressor, and is remarkable in energy-saving effect. The microcomputer of the variable-frequency air conditioner monitors key signals of the indoor environment in real time, compares the key signals with an internal set value, outputs control signals to the frequency converter after operation treatment, and controls and changes the rotating speed of the compressor through frequency adjustment of the frequency converter, so that the power of the variable-frequency air conditioner is continuously adjusted to achieve the aim of adjusting refrigeration and heating, and the indoor temperature and humidity adjusting requirement of dynamic change is met.
Along with the continuous promotion of the popularity of variable frequency air conditioner, around how to reduce the air conditioner control panel cost, especially the variable frequency drive plate cost of air conditioner compressor and fan, different solutions have been put forward in the trade.
The main trend is to increase the carrier frequency, reduce the inductance of PFC and the capacity of DC bus capacitor. However, as the inductance of the PFC inductor is reduced, the anti-interference capability to the power grid is correspondingly reduced, so that improvement is required to be made on the filter, the capacitance capacity of the filter is increased, but leakage current is increased when the capacitance capacity is too large, the cost of the filter is increased, the safety requirement is difficult to achieve, and the resonance problem cannot be thoroughly solved.
The mechanism of resonance generation is: because PFC inductance is smaller, leakage inductance at the front end of an input power supply cannot be ignored at the moment, the leakage inductance, a filter capacitor and the PFC inductance form an LCL resonant circuit together, the resonant frequency changes along with the change of the leakage inductance, when the leakage inductance is larger, the input current oscillates, and then the input voltage oscillates simultaneously, so that abnormal operation of variable frequency drive is finally caused, and even abnormal operation of other equipment or electric appliances at the same access point of a power grid is caused.
Based on the resonance generation mechanism, the existing air conditioner variable frequency driver with PFC control is easy to generate resonance under a weak power grid.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a PFC control method and a PFC control system for inhibiting voltage and current resonance of a weak current network, which are used for solving the technical problem that the existing variable frequency drive of an air conditioner with PFC control is easy to resonate under the weak current network, thereby achieving the purposes of remarkably reducing the cost and improving the system performance and reliability.
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a PFC control method for suppressing voltage-current resonance of a weak power grid, comprising the steps of:
the PFC control circuit of the variable frequency driver under the weak current network is controlled by adopting the feedforward of the input voltage, the actual value of PFC inductance current is used as the feedback quantity of the controller, and the PFC inductance current is used as the input quantity of the harmonic suppression controller and is output and fed back to the PWM controller;
the current and voltage resonance under a weak current network is restrained by controlling the duty ratio of a power semiconductor switch controlled by PFC;
the PFC control circuit of the variable frequency driver under the weak power grid comprises: the power supply circuit comprises an equivalent resistor, an equivalent inductor, an equivalent filter capacitor of a variable frequency drive filter, a rectifier bridge, a variable frequency drive PFC inductor, a follow current diode of PFC, a PFC-controlled power semiconductor switch, a direct current bus capacitor and a variable frequency drive inverter bridge;
the rectifier bridge is provided with a first wiring terminal and a second wiring terminal, and the variable frequency drive inverter bridge is provided with a third wiring terminal and a fourth wiring terminal which correspond to the rectifier bridge;
the variable-frequency driven PFC inductor and the follow current diode of the PFC are sequentially connected in series between the first terminal and the third terminal;
an equivalent filter capacitor of the variable frequency drive filter is connected in parallel between the first wiring end and the second wiring end, the equivalent filter capacitor of the variable frequency drive filter is close to one side of the rectifier bridge, the direct current bus capacitor is connected in parallel between the third wiring end and the fourth wiring end, and the direct current bus capacitor is close to one side of the variable frequency drive inverter bridge;
one end of the PFC-controlled power semiconductor switch is electrically connected to a line between the variable-frequency driven PFC inductor and a freewheeling diode of the PFC, and the other end of the PFC-controlled power semiconductor switch is connected to a line between the second wiring terminal and the fourth wiring terminal;
the equivalent resistor is arranged between the mains supply and the variable frequency drive, and forms equivalent impedance with the equivalent inductor, and the equivalent impedance and the mains supply form a weak power grid together.
As a preferred embodiment of the present invention, when controlling the duty ratio of the PFC-controlled power semiconductor switch, the method includes:
acquiring a PFC inductance current actual value i of a PFC control circuit of the variable frequency driver under the weak current network 2 And the voltage v on the equivalent filter capacitor of the variable frequency drive filter 1 ；
The PFC control circuit of the variable frequency driver under the weak current network is characterized in that the PFC inductance current actual value i is under a high-frequency signal 2 And the voltage v on the equivalent filter capacitor of the variable frequency drive filter 1 Satisfy equation 1:
sC 1 v 1 ＝i 1 -i 2 (1)；
wherein C is 1 Equivalent filter capacitance, i, of the variable frequency drive filter 1 Is the grid current.
As a preferred embodiment of the present invention, when controlling the duty ratio of the PFC-controlled power semiconductor switch, the method further includes:
acquiring a direct current bus set voltage and a direct current bus actual voltage of a PFC control circuit of a variable frequency driver under the weak current network;
according to the difference value between the set voltage of the direct current bus and the actual voltage of the direct current bus, a PFC inductance current set value is obtained through calculation of a PI controller
As a preferred embodiment of the present invention, when controlling the duty ratio of the PFC-controlled power semiconductor switch, the method further includes:
acquiring a PFC inductance current set value of a PFC control circuit of a variable frequency driver under the weak current networkAnd PFC inductor current actual value i 2 ；
According to the PFC inductance current set valueAnd the PFC inductor current actual value i 2 The error of (2) is calculated by a PI controller to obtain PFC output command voltage v c 。
As a preferred embodiment of the invention, the PFC inductance current set value is obtained through calculation of a PI controllerAnd PFC output command voltage v c When the transfer function of the PI controller is as shown in formula 2:
wherein k is p Is a proportionality coefficient, k i And s is a Law operator and is an integral coefficient.
As a preferred embodiment of the present invention, when controlling the duty ratio of the PFC-controlled power semiconductor switch, the method further includes:
obtaining the voltage v on the equivalent filter capacitor of the variable frequency drive filter 1 Through a feed forward amplifier G f (s) the obtained feedforward voltage v ff Wherein G is f (s)＝k ff ，k ff Taking a constant between 0 and 1.
As a preferred embodiment of the present invention, when controlling the duty ratio of the PFC-controlled power semiconductor switch, the method further includes:
acquiring the PFC inductance current actual value i 2 And the PFC inductance current actual value i 2 Input to ADF controller to obtain active damping compensation voltage v ad 。
In a preferred embodiment of the present invention, the PFC inductor current i is set to 2 Input to ADF controller to obtain active damping compensation voltage v ad When the transfer function of the ADF controller is as shown in equation 3:
wherein k is ad As a proportionality coefficient omega ad For the cut-off frequency s is the Laplace operator.
As a preferred embodiment of the present invention, when controlling the duty ratio of the PFC-controlled power semiconductor switch, the method further includes:
acquiring the feedforward voltage v ff The PFC outputs a command voltage v c Said active damping compensation voltage v ad And the actual voltage of the direct current bus, and the duty ratio of the PFC-controlled power semiconductor switch is obtained, as shown in formula 4:
in the formula, v dc And the actual voltage of the direct current bus is the actual voltage of the direct current bus.
A PFC control system for suppressing voltage-current resonance in a weak power network, comprising:
parameter acquisition unit: a PFC inductance current actual value i for obtaining frequency conversion driver PFC control circuit under weak current net 2 Voltage v on equivalent filter capacitor of said variable frequency drive filter 1 Setting voltage of the direct current bus and actual voltage of the direct current bus;
inductance current set value acquisition unit: the PFC inductance current set value is obtained through calculation of a PI controller according to the difference value between the set voltage of the direct current bus and the actual voltage of the direct current bus
An output instruction voltage acquisition unit: for setting the value according to the PFC inductance currentAnd the PFC inductor current actual value i 2 The error of (2) is calculated by a PI controller to obtain PFC output command voltage v c ；
A feedforward voltage acquisition unit: for obtaining the voltage v on the equivalent filter capacitor of the variable frequency drive filter 1 Through a feed forward amplifier G f (s) the obtained feedforward voltage v ff ；
An active damping compensation voltage acquisition unit: for obtaining the PFC inductance current actual value i 2 And the PFC inductance current actual value i 2 Input to ADF controller to obtain active damping compensation voltage v ad ；
Duty ratio acquisition unit: for obtaining the feedforward voltage v ff The PFC outputs a command voltage v c Said active damping compensation voltage v ad And the actual voltage of the direct current bus, and obtaining the PFC-controlled powerThe duty cycle of the semiconductor switch.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the virtual resistor is connected in series at the input side of the frequency converter in an active damping control mode, so that current and voltage resonance of the air conditioner frequency conversion driver with PFC control can be effectively inhibited under a weak current network, and a hardware circuit is not required to be additionally increased.
The invention is described in further detail below with reference to the drawings and the detailed description.
Drawings
FIG. 1-topology diagram of a PFC control circuit of a variable frequency driver under a weak power network according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a PFC control circuit of a variable frequency driver under a weak power grid with an equivalent resistor ignored;
fig. 3-a current control block diagram of a PFC control method for suppressing voltage-current resonance in a weak current network according to an embodiment of the present invention.
Reference numerals illustrate: 1. a commercial power; 2. equivalent resistance; 3. equivalent inductance; 4. equivalent filter capacitance of the variable frequency drive filter; 5. a rectifier bridge; 6. a variable frequency driven PFC inductor; 7. a freewheeling diode of the PFC; 8. a PFC-controlled power semiconductor switch; 9. a DC bus capacitor 9; 10. variable frequency driving inverter bridge; 11. and outputting the motor load.
Detailed Description
The PFC control method for inhibiting voltage-current resonance of the weak current network provided by the invention comprises the following steps:
step S1: the PFC control circuit of the variable frequency driver under the weak current network is controlled by adopting the feedforward of the input voltage, the actual value of PFC inductance current is used as the feedback quantity of the controller, and the PFC inductance current is used as the input quantity of the harmonic suppression controller and is output and fed back to the PWM controller;
step S2: the current and voltage resonance under a weak current network is restrained by controlling the duty ratio of the PFC-controlled power semiconductor switch 8;
the PFC control circuit of the variable frequency driver under the weak current network comprises: the power inverter comprises an equivalent resistor 2, an equivalent inductor 3, an equivalent filter capacitor 4 of a variable frequency drive filter, a rectifier bridge 5, a variable frequency drive PFC inductor 6, a follow current diode 7 of PFC, a PFC-controlled power semiconductor switch 8, a direct current bus capacitor 9 and a variable frequency drive inverter bridge 10;
rectifier bridge 5 has a first terminal and a second terminal, and inverter bridge 10 has a third terminal and a fourth terminal corresponding to rectifier bridge 5;
a variable-frequency driven PFC inductor 6 and a PFC follow current diode 7 are sequentially connected in series between the first terminal and the third terminal;
an equivalent filter capacitor 4 of the variable frequency drive filter is connected in parallel between the first wiring end and the second wiring end, the equivalent filter capacitor 4 of the variable frequency drive filter is close to one side of the rectifier bridge 5, a direct current bus capacitor 9 is connected in parallel between the third wiring end and the fourth wiring end, and the direct current bus capacitor 9 is close to one side of the variable frequency drive inverter bridge 10;
one end of the PFC-controlled power semiconductor switch 8 is electrically connected to a line between the variable-frequency driven PFC inductor 6 and the freewheeling diode 7 of the PFC, and the other end of the PFC-controlled power semiconductor switch 8 is connected to a line between the second wiring terminal and the fourth wiring terminal;
the equivalent resistor 2 is arranged between the mains supply 1 and the variable frequency drive, and forms equivalent impedance with the equivalent inductor 3, and the equivalent impedance and the mains supply 1 form a weak power grid together.
In the above step S2, when the duty ratio of the PFC-controlled power semiconductor switch 8 is controlled, it includes:
acquiring PFC inductance current actual value i of PFC control circuit of variable frequency driver under weak current network 2 And the voltage v across the equivalent filter capacitor 4 of the variable frequency drive filter 1 ；
The PFC control circuit of the variable frequency driver under the weak current network is used for controlling the actual value i of PFC inductance current under the high-frequency signal 2 And the voltage v across the equivalent filter capacitor 4 of the variable frequency drive filter 1 Satisfy equation 1:
sC 1 v 1 ＝i 1 -i 2 (1)；
wherein C is 1 Equivalent filter capacitor 4, i for frequency conversion driving filter 1 Is the grid current.
In the above step S2, when the duty ratio of the PFC-controlled power semiconductor switch 8 is controlled, it further includes:
acquiring a direct current bus set voltage and a direct current bus actual voltage of a PFC control circuit of a variable frequency driver under a weak current network;
according to the difference value between the set voltage of the direct current bus and the actual voltage of the direct current bus, a PFC inductance current set value is obtained through calculation of a PI controller
In the above step S2, when the duty ratio of the PFC-controlled power semiconductor switch 8 is controlled, it further includes:
acquiring PFC inductance current set value of PFC control circuit of variable frequency driver under weak current networkAnd PFC inductor current actual value i 2 ；
According to the PFC inductance current set valueAnd PFC inductor current actual value i 2 The error of (2) is calculated by a PI controller to obtain PFC output command voltage v c 。
Further, the PFC inductance current set value is obtained through calculation of the PI controllerAnd PFC output command voltage v c When the transfer function of the PI controller is as shown in equation 2:
wherein k is p Is a proportionality coefficient, k i And s is a Law operator and is an integral coefficient.
In the above step S2, when the duty ratio of the PFC-controlled power semiconductor switch 8 is controlled, it further includes:
obtaining the voltage v on the equivalent filter capacitor 4 of the variable frequency drive filter 1 Through a feed forward amplifier G f (s) the obtained feedforward voltage v ff Wherein G is f (s)＝k ff ，k ff Taking a constant between 0 and 1.
In the above step S2, when the duty ratio of the PFC-controlled power semiconductor switch 8 is controlled, it further includes:
acquiring the actual value i of PFC inductance current 2 And the PFC inductance current actual value i 2 Input to ADF controller to obtain active damping compensation voltage v ad 。
Further, the PFC inductor current i is calculated 2 Input to ADF controller to obtain active damping compensation voltage v ad When the transfer function of the ADF controller is as shown in equation 3:
wherein k is ad As a proportionality coefficient omega ad For the cut-off frequency s is the Laplace operator.
In the above step S2, when the duty ratio of the PFC-controlled power semiconductor switch 8 is controlled, it further includes:
obtaining a feedforward voltage v ff PFC output command voltage v c Active damping compensation voltage v ad And the actual voltage of the dc bus, and the duty cycle of the PFC-controlled power semiconductor switch 8 is obtained as shown in equation 4:
in the formula, v dc Is the actual voltage of the direct current bus.
The PFC control system for inhibiting voltage-current resonance of a weak current network provided by the invention comprises the following components: the device comprises a parameter acquisition unit, an inductance current set value acquisition unit, an output instruction voltage acquisition unit, a feedforward voltage acquisition unit, an active damping compensation voltage acquisition unit and a duty ratio acquisition unit.
Parameter acquisition unit: PFC inductance current actual value i for PFC control circuit of variable frequency driver under weak current network 2 Voltage v across equivalent filter capacitor 4 of variable frequency drive filter 1 Setting voltage of the direct current bus and actual voltage of the direct current bus.
Inductance current set value acquisition unit: the PFC inductance current set value is obtained through calculation of the PI controller according to the difference value between the set voltage of the direct current bus and the actual voltage of the direct current bus
An output instruction voltage acquisition unit: for setting the value according to PFC inductor currentAnd PFC inductor current actual value i 2 The error of (2) is calculated by a PI controller to obtain PFC output command voltage v c 。
A feedforward voltage acquisition unit: for obtaining the voltage v at the equivalent filter capacitor 4 of a variable frequency drive filter 1 Through a feed forward amplifier G f (s) the obtained feedforward voltage v ff 。
An active damping compensation voltage acquisition unit: for obtaining the actual value i of PFC inductance current 2 And the PFC inductance current actual value i 2 Input to ADF controller to obtain active damping compensation voltage v ad 。
Duty ratio acquisition unit: for obtaining feed-forward voltage v ff PFC output command voltage v c Active damping compensation voltage v ad And the actual voltage of the dc bus and the duty cycle of the PFC-controlled power semiconductor switch 8.
The following examples are further illustrative of the present invention, but the scope of the present invention is not limited thereto.
The topology structure diagram of the PFC control circuit of the variable frequency driver under the weak current network is shown in figure 1.
In fig. 1, the utility power 1 represents a power grid with infinite output impedance, and an equivalent resistor 2 and an equivalent inductor 3 between the power grid and the variable frequency drive, namely equivalent impedance, and a network formed by the equivalent impedance and the utility power 1 together is called a weak power grid. The PFC control circuit of the present embodiment further includes: the variable frequency drive filter comprises an equivalent filter capacitor 4, a rectifier bridge 5, a variable frequency drive PFC inductor 6, a follow current diode 7 of PFC, a PFC-controlled power semiconductor switch 8, a direct current bus capacitor 9 and a variable frequency drive inverter bridge 10.
The variable-frequency drive inverter bridge 10 is connected with an output motor load 11, and the PFC-controlled power semiconductor switch 8 is controlled to be opened and closed through software.
Since the equivalent resistance 2 is far smaller than the inductance of the equivalent inductance 3 under the high-frequency signal, the equivalent resistance 2 can be ignored, and no influence is caused on harmonic suppression. The topology structure diagram of the PFC control circuit of the variable frequency driver under the weak power grid after neglecting the equivalent resistor 2 is shown in figure 2.
From fig. 2 (equivalent circuit diagram) it can be derived that:
sC 1 v 1 ＝i 1 -i 2
in the formula, v 1 The voltage on the equivalent filter capacitor 4 of the variable frequency drive filter sampled by the MCU, C 1 Equivalent filter capacitor 4, i for frequency conversion driving filter 1 For grid current, i 2 The PFC inductor current actual value sampled by the MCU.
v 2 ＝v g -sL 1 i 1 -sL 2 i 2
In the formula, v g Is the absolute value of the voltage of the power grid, v 2 For the output voltage of PFC inductance, L 1 Is equivalent inductance 3, L 2 PFC inductance 6 for variable frequency drive, s is Lawster operator.
Since the software only algorithmically controls the duty cycle of the PFC-controlled power semiconductor switch 8, v 2 Is an equivalent value, and is calculated by the following formula:
v 2 ＝v dc ·(1-d)
in the formula, v dc D is the duty cycle of the PFC-controlled power semiconductor switch 8, which is the dc bus actual voltage.
According to the relation, the PFC control circuit of the variable frequency driver under the weak current network adopts feedforward control of input voltage and adopts the actual value i of PFC inductance current 2 As the controller feedback amount, and at the same time as the input amount of the harmonic suppression controller, and the output is fed back to the PWM controller, the current control block diagram is as shown in fig. 3.
In FIG. 3, G c (s) is a transfer function of the PI controller:
wherein k is p Is a proportionality coefficient, k i And s is a Law operator and is an integral coefficient.
G ad (s) is a transfer function of the ADF (active damping filter) controller, which is a first order high pass filter:
wherein k is ad As a proportionality coefficient omega ad For the cut-off frequency s is the Laplace operator. The two parameters of the proportionality coefficient and the cut-off frequency need to be actually set according to the inductance of the PFC and the parameters of the filter.
Based on the above design, the implementation manner of this embodiment is as follows:
step one:
PFC inductance current actual value i of PFC control circuit of variable frequency driver under sampling weak current network 2 And the voltage v across the equivalent filter capacitor 4 of the variable frequency drive filter 1 ；
Step two:
the PFC inductance current setting is obtained through calculation of a PI controller according to the difference value between the DC bus setting voltage and the DC bus actual voltageValue of
Step three:
according to the PFC inductance current set valueAnd PFC inductor current actual value i 2 The error of (2) is calculated by a PI controller to obtain PFC output command voltage v c ；
Step four:
sampling voltage v on equivalent filter capacitor 4 of variable frequency drive filter 1 Through a feed forward amplifier G f (s) the obtained feedforward voltage v ff Wherein G is f (s)＝k ff ，k ff Taking the number of fields between 0 and 1.
Step five:
the PFC inductance current actual value i 2 Input to ADF controller to obtain active damping compensation voltage v ad ；
Step six:
according to the feedforward voltage v ff PFC output command voltage v c Active damping compensation voltage v ad And the actual voltage of the direct current bus, the duty ratio of the PFC-controlled power semiconductor switch 8 is obtained:
in the formula, v dc Is the actual voltage of the direct current bus.
The above embodiments are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, but any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention are intended to be within the scope of the present invention as claimed.

Claims (8)

1. A PFC control method for suppressing voltage-current resonance of a weak current network, comprising the steps of:
the PFC control circuit of the variable frequency driver under the weak current network is controlled by adopting the feedforward of the input voltage, the actual value of PFC inductance current is used as the feedback quantity of the controller, and the PFC inductance current is used as the input quantity of the harmonic suppression controller and is output and fed back to the PWM controller;
the current and voltage resonance under a weak current network is restrained by controlling the duty ratio of a power semiconductor switch controlled by PFC;
the PFC control circuit of the variable frequency driver under the weak power grid comprises: the power supply circuit comprises an equivalent resistor, an equivalent inductor, an equivalent filter capacitor of a variable frequency drive filter, a rectifier bridge, a variable frequency drive PFC inductor, a follow current diode of PFC, a PFC-controlled power semiconductor switch, a direct current bus capacitor and a variable frequency drive inverter bridge;
the rectifier bridge is provided with a first wiring terminal and a second wiring terminal, and the variable frequency drive inverter bridge is provided with a third wiring terminal and a fourth wiring terminal which correspond to the rectifier bridge;
the variable-frequency driven PFC inductor and the follow current diode of the PFC are sequentially connected in series between the first terminal and the third terminal;
an equivalent filter capacitor of the variable frequency drive filter is connected in parallel between the first wiring end and the second wiring end, the equivalent filter capacitor of the variable frequency drive filter is close to one side of the rectifier bridge, the direct current bus capacitor is connected in parallel between the third wiring end and the fourth wiring end, and the direct current bus capacitor is close to one side of the variable frequency drive inverter bridge;
one end of the PFC-controlled power semiconductor switch is electrically connected to a line between the variable-frequency driven PFC inductor and a freewheeling diode of the PFC, and the other end of the PFC-controlled power semiconductor switch is connected to a line between the second wiring terminal and the fourth wiring terminal;
the equivalent resistor is arranged between the mains supply and the variable frequency drive, and forms equivalent impedance with the equivalent inductor, and the equivalent impedance and the mains supply form a weak power grid together;
wherein when controlling the duty cycle of the PFC-controlled power semiconductor switch, it comprises:
acquiring the PFC inductance current actual valueAnd the PFC inductor current actual value is +.>Input to ADF controller to obtain active damping compensation voltage +.>；
At the actual value of the PFC inductance currentInput to ADF controller to obtain active damping compensation voltage +.>When the transfer function of the ADF controller is as shown in equation 3:
（3）；
in the method, in the process of the invention,is a proportional coefficient->For cut-off frequency +.>Is a Lawster operator.
2. The PFC control method for suppressing voltage-current resonance in a weak current network according to claim 1, wherein when controlling a duty cycle of the PFC-controlled power semiconductor switch, comprising:
acquiring PFC control circuit of variable frequency driver under weak current networkPFC inductor current actual valueAnd the voltage on the equivalent filter capacitance of the variable frequency drive filter +.>；
The PFC control circuit of the variable frequency driver under the weak current network is used for controlling the actual value of the PFC inductance current under a high-frequency signalAnd the voltage on the equivalent filter capacitance of the variable frequency drive filter +.>Satisfy equation 1:
（1）；
in the method, in the process of the invention,equivalent filter capacitance for the variable frequency drive filter, < >>Is the grid current.
3. The PFC control method for suppressing voltage-current resonance in a weak current network according to claim 2, further comprising, when controlling a duty cycle of the PFC-controlled power semiconductor switch:
acquiring a direct current bus set voltage and a direct current bus actual voltage of a PFC control circuit of a variable frequency driver under the weak current network;
according to the difference value between the set voltage of the direct current bus and the actual voltage of the direct current bus, a PFC inductance current set value is obtained through calculation of a PI controller。
4. The PFC control method for suppressing voltage-current resonance in a weak current network according to claim 3, further comprising, when controlling a duty cycle of the PFC-controlled power semiconductor switch:
acquiring a PFC inductance current set value of a PFC control circuit of a variable frequency driver under the weak current networkAnd PFC inductor current actual value +.>；
According to the PFC inductance current set valueAnd the PFC inductor current actual value +.>The error of (2) is calculated by a PI controller to obtain PFC output command voltage +.>。
5. The PFC control method for suppressing voltage-current resonance in a weak current network according to claim 4, wherein the PFC inductor current set value is calculated by a PI controllerAnd PFC output command voltage +>When the transfer function of the PI controller is as shown in formula 2:
（2）；
in the method, in the process of the invention,is a proportional coefficient->For the integral coefficient +.>Is a Lawster operator.
6. The PFC control method for suppressing voltage-current resonance in a weak current network according to claim 5, further comprising, when controlling a duty cycle of the PFC-controlled power semiconductor switch:
acquiring the voltage on the equivalent filter capacitor of the variable frequency drive filterThrough a feed forward amplifier->The obtained feedforward voltage +.>Wherein->，/>Taking a constant of 0-1.
7. The PFC control method for suppressing voltage-current resonance in a weak current network according to claim 1, further comprising, when controlling a duty cycle of the PFC-controlled power semiconductor switch:
obtaining a feed-forward voltagePFC output command Voltage +.>The active damping compensation voltage +.>And obtaining the actual voltage of the direct current bus and the duty ratio of the PFC-controlled power semiconductor switch, as shown in a formula 4:
（4）；
in the method, in the process of the invention,and the actual voltage of the direct current bus is the actual voltage of the direct current bus.
8. A PFC control system for suppressing voltage-current resonance in a weak power network, comprising:
parameter acquisition unit: a PFC inductance current actual value for obtaining frequency conversion driver PFC control circuit under weak current netVoltage on equivalent filter capacitor of frequency conversion driving filter +.>Setting voltage of the direct current bus and actual voltage of the direct current bus;
inductance current set value acquisition unit: the PFC inductance current set value is obtained through calculation of a PI controller according to the difference value between the set voltage of the direct current bus and the actual voltage of the direct current bus；
An output instruction voltage acquisition unit: for setting the value according to the PFC inductance currentAnd the PFC inductor current actual value +.>The error of (2) is calculated by a PI controller to obtain PFC output command voltage +.>；
A feedforward voltage acquisition unit: for obtaining the voltage on the equivalent filter capacitor of the variable frequency drive filterThrough a feed forward amplifier->The obtained feedforward voltage +.>；
An active damping compensation voltage acquisition unit: for obtaining the PFC inductor current actual valueAnd the PFC inductor current actual value is +.>Input to ADF controller to obtain active damping compensation voltage +.>；
Duty ratio acquisition unit: for obtaining the feed-forward voltageThe PFC output command voltage +.>The active damping compensation voltage +.>The actual voltage of the direct current bus is obtained, and the duty ratio of the PFC-controlled power semiconductor switch is obtained;
wherein the active damping compensation voltage acquisition unit acquires the PFC inductance current actual valueInput to ADF controller to obtain active damping compensation voltage +.>When the transfer function of the ADF controller is as shown in equation 3:
（3）；
in the method, in the process of the invention,is a proportional coefficient->For cut-off frequency +.>Is a Lawster operator.
CN202311232566.2A 2023-09-22 2023-09-22 PFC control method and system for inhibiting voltage and current resonance of weak current network Active CN117394673B (en)

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CN108767873A (en) * 2018-05-23 2018-11-06 湖南大学 A kind of highly reliable damping remodeling procedure of large size new energy power station
CN113285624A (en) * 2021-06-02 2021-08-20 湖南工业大学 Active damping high-frequency resonance suppression method
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