CN113346735A - PFC control method and device, air conditioner and computer readable storage medium - Google Patents
PFC control method and device, air conditioner and computer readable storage medium Download PDFInfo
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Abstract
The invention provides a PFC control method, a PFC control device, an air conditioner and a computer-readable storage medium, which are used for controlling a PFC system, wherein the PFC system comprises a PFC circuit device and a PFC control device, the PFC circuit device comprises a PFC circuit and a load, the PFC control device comprises a voltage outer ring module, a current inner ring module and a PWM module, and the control method comprises the following steps: estimating and obtaining the output current I of the load0Will output a current I0Injecting a voltage outer loop module according to the output current I0Obtaining a reference current Iref. The invention obtains the load output current I through estimation0Adding the reference current I into a control loop as the reference current I of the current inner loop modulerefPart of reference current I when sudden changes in load occurrefThe output current estimation module has simple structure, improves the dynamic response capability of the PFC output voltage through the change of a software algorithm under the condition of not increasing the hardware cost, and has the advantages of directly changing the PFC output voltage to dynamically respond to the change of the load, improving the dynamic response capability of the PFC output voltage and havingThe system cost is favorably reduced.
Description
Technical Field
The invention relates to the field of air conditioners, in particular to a PFC control method and device, an air conditioner and a computer readable storage medium.
Background
The Boost type PFC circuit topology structure commonly adopted by the existing variable frequency air conditioner is shown in figure 1, an AC power supply supplies power to a permanent magnet synchronous motor through AC-DC-AC conversion, and the control of the circuit generally adopts a double-ring control structure with a current ring as an inner ring and a voltage ring as an outer ring.
In order to ensure the fast tracking of the current, the bandwidth of the current inner loop module is generally set to be higher; however, due to the existence of the output voltage ripple of twice the grid frequency, the frequency bandwidth of the voltage outer loop module cannot be too high, typically several tens of hertz, otherwise the ripple will be introduced in the control quantity, so that the input current harmonic wave will increase. Because the bandwidth of the voltage outer loop module is very low, the output voltage has a slow response to load sudden changes, the dynamic performance of the system is poor, and the system needs to be optimized.
Disclosure of Invention
The invention solves the problems that in the prior art, the bandwidth of a voltage outer ring module is very low, the response of output voltage to load sudden change is very slow, and the dynamic performance of a system is poor.
In order to solve the above problems, the present invention discloses a PFC control method for controlling a PFC system, the PFC system including a PFC circuit device and a PFC control device, the PFC circuit device including a PFC circuit and a load, the PFC control device including a voltage outer loop module, a current inner loop module and a PWM module, the voltage outer loop module being configured to output a reference current I to the current inner loop modulerefThe current inner ring module is used for generating a reference current I according torefControlling the PWM moduleThe output PWM waveform, the control method comprises: estimating and obtaining the output current I of the load0And applying the output current I0Injecting the voltage outer ring module according to the output current I0Obtaining the reference current IrefThe reference current IrefFor fast response of the PFC circuit output voltage upon said load change.
Output current I due to load0Directly related to the change of the load, when the load suddenly changes, the output current I0An abrupt change will also occur, in which arrangement the output current I0Will directly result in the reference current IrefThe change of the PWM waveform further causes the change of the PWM waveform to drive the on-off change of the switching tube, and finally causes the output voltage of the PFC circuit to change rapidly, and the change is mainly caused by the output current I of the load0Therefore, the method is not influenced by the low-pass filter, the rapid dynamic response of the output voltage of the PFC circuit is realized, and the response speed of the system is greatly improved.
Further, the control method comprises the following steps:
step S1, calculating and acquiring the output current I of the load0And will output a current I0And K0Multiplying and outputting the voltage to the voltage outer ring module 4;
step S2, according to output current I in the voltage outer loop module0Calculating reference current I by correlationrefAnd applying the reference current IrefTransmitting to the current inner ring module;
step S3, according to the reference current I in the current inner loop modulerefOutputting after correlation calculation, and transmitting an output value to a PWM module;
step S4, the PWM module generates a PWM waveform signal according to the output value of the current inner loop module, and the PWM waveform signal is used for controlling the on-off of a switch tube in the PFC circuit;
wherein, K0The specific value is a preset value for the output current injection coefficient.
Through the steps, the on-off of the switch tube in the PFC circuit is connected withOutput current I of the load0The correlation is carried out, the rapid dynamic response of the output voltage of the PFC circuit is realized, and the response speed of the system is greatly improved.
Further, the output current I in step S10Calculated according to the following formula:
wherein, ILIs the current of the inductor, m is the duty ratio, C is the capacitance value of the capacitor,
the derivative of the capacitor voltage with respect to time.
Wherein IL、UcT is a detection value which can be realized by a system in the prior art, the capacitance value C of the capacitor is a fixed quantity, the control algorithm of the duty ratio m in the PFC is a known quantity, the parameters are not difficult to obtain, only the algorithm is needed to be adjusted, and the hardware cost is not increased, so that the output current I can be conveniently obtained through the formula0The value of (2) is obtained, so that the response speed of the output voltage of the PFC circuit is greatly improved under the condition of not increasing the hardware cost, and a user can obtain better use experience.
Further, the step S2 includes:
step S21, a given voltage U is setrefAnd the output voltage U of the PFC circuit0Comparing, and outputting the difference value after being regulated by the voltage ring regulator;
a step S22 of adding the output value in the step S21 and the output value in the step S1 and outputting the result;
step S23, the output value in step S22 is compared with the input voltage UdMultiplying and outputting the result, wherein the output value is the reference current Iref；
Wherein the input voltage UdThe output value of step S1 is I for the input voltage of PFC circuit0×K0。
According to the above steps can be based on the output currentI0Obtaining a reference current Iref。
Further, step S3 includes:
step S31, converting the reference current IrefAnd an input current ILComparing, and outputting the difference value after being regulated by a current loop regulator, wherein the input current ILIs the current in the inductor of the PFC circuit.
The output value of the above step is I0Due to the influence of the change, the PWM waveform can be rapidly changed when the load is changed, and the on-off of a switch tube in the PFC circuit is controlled.
The invention also discloses a PFC control device, which is used for controlling the PFC circuit device, the PFC circuit device comprises a PFC circuit and a load, and the PFC control device comprises:
a voltage outer ring module for outputting a reference current I to the current inner ring moduleref；
A current inner loop module for generating a reference current IrefControlling a PWM waveform output by the PWM module;
the PWM module is used for generating a PWM waveform according to the output value of the current inner loop module, and the PWM waveform is used for controlling the on-off of a switch tube in the PFC circuit;
an output current estimation module for estimating an output current I of the load0And applying the output current I0Injection into the voltage outer loop module for the reference current IrefAnd (4) calculating.
The PFC circuit is a boost type circuit and comprises an inductor, a diode, a switching tube and a capacitor, the connection relation of all components in the boost type PFC circuit is the prior art, and when the load suddenly changes, the output current I is output0Will also suddenly change, the PFC control device will output the current I0Directly resulting in the reference current I when changedrefThe change of the PWM waveform further causes the change of the PWM waveform, drives the on-off change of the switch tube, and finally causes the rapid change of the PFC output voltage, thereby greatly improving the response speed of the PFC circuit output voltage and avoiding the influence of a low-pass filter.
Go toThe voltage outer ring module comprises an output voltage U0Input part, given voltage UrefInput unit and input voltage UdThe input part comprises three signal input parts, and further comprises a first subtracter, a voltage loop regulator, a first multiplier and a first adder, wherein the input end of the first subtracter is respectively connected with an output voltage U0Input part, given voltage UrefAn input part, wherein the output end of the first subtracter is connected with the input end of a voltage ring adjuster, the output end of the voltage ring adjuster is connected with one input end of the first adder, the other input end of the first adder is connected with the output end of the output current estimation module, the output end of the first adder is connected with one input end of a first multiplier, and the other input end of the first multiplier is connected with an input voltage UdThe output end of the first multiplier is connected with the current inner loop module; wherein the output voltage U0An input voltage U as an output voltage of the PFC circuitdFor the input voltage of the PFC circuit, a given voltage UrefIs a preset reference voltage.
The specific control calculation method in the voltage outer loop module comprises the following steps: 1, setting a given voltage U in the first subtracterrefAnd the output voltage U of the PFC circuit0Comparing, and outputting the difference value after being regulated by the voltage ring regulator; 2, adding the output value of the voltage loop regulator and the output value of the output current estimation module by a first adder and outputting the added value; 3, the output value of the first adder and the input voltage U of the PFC circuit are processed by a first multiplierdThe multiplied output is the reference current I of the input current inner loop moduleref。
Further, the current inner loop module comprises an input current ILThe input part, the current inner loop module also includes a second subtracter and a current loop regulator, the input end of the second subtracter is respectively connected with the input current ILThe output end of the second subtracter is connected with the input end of the current loop regulator, and the output end of the current loop regulator is connected with the PWM module; wherein the input powerStream ILIs the current of the input inductor in the PFC circuit.
The specific control calculation method in the current inner loop module comprises the following steps: the inductive current I is converted by the second subtracterLAnd a reference current IrefComparing, outputting the comparison value after being regulated by the current loop regulator, inputting the output value of the current loop regulator into the PWM module to generate a PWM waveform signal, controlling the on-off of the switching tube by the PWM waveform signal, and further enabling the current I of the inductorLThe waveform of the voltage tracking circuit can well track the output voltage U of the rectifying circuitdThe waveform change of the power factor correction circuit greatly reduces current harmonic waves so as to achieve the purpose of improving the power factor.
Further, the output voltage U0Input unit and input current ILThe input part and the output end of the current loop regulator are also respectively connected with the input end of the output current estimation module.
The output voltage U0Current of the inductor ILAnd the duty ratio m output by the current loop regulator is used as an input value of an output current estimation module to participate in the output current I0And (4) estimating.
Further, the output current estimation module at least comprises a second multiplier, a third subtractor, a fourth subtractor and a differentiator, wherein the input end of the second multiplier is respectively connected with the input current ILAn input part and an output end of the current loop regulator, wherein an input end of the second multiplier is connected with one input end of the third subtracter, and the other input end of the third subtracter is connected with the input current ILAn input unit, wherein an output terminal of the third subtractor is connected to an input terminal of the fourth subtractor, another input terminal of the fourth subtractor is connected to an output terminal of the differentiator, and an input terminal of the differentiator is connected to the output voltage U0And the output end of the fourth subtracter is connected with the input end of the first adder.
The specific control calculation method in the output current estimation module is as follows: 1, inputting current I through the second multiplierLMultiplying the duty ratio m and outputting; 2, byThe third subtracter converts the input current ILComparing the difference value with the output value of the second multiplier and outputting the difference value; calculating the time derivative of the capacitor voltage by means of said differentiator
Wherein U isc＝U0And will be
Multiplying the product by C and outputting; comparing an output value of the third subtractor with an output value of the differentiator through a fourth subtractor, and multiplying a difference value by K0Rear output, K0For output current injection coefficient, K0Is a preset value.
The invention also discloses an air conditioner, which comprises a computer readable storage medium and a processor, wherein the computer readable storage medium is used for storing a computer program, and the computer program is read by the processor and runs to realize the PFC control method.
Compared with the prior art, the air conditioner and the PFC control method have the same advantages, and are not repeated herein.
The invention also discloses a computer readable storage medium, which stores a computer program, and when the computer program is read and executed by a processor, the PFC control method is realized.
Compared with the prior art, the PFC control method, the PFC control device, the air conditioner and the computer-readable storage medium have the following advantages:
the invention adds an output current estimation module in a control module and obtains the load output current I through estimation0Adding the reference current I into a control loop as the reference current I of the current inner loop modulerefA part of the reference current I of the current inner loop module when the load is suddenly changedrefWill be directly changed, thereby leading the PFC output voltage to dynamically respond the change of the load, increasing the control flexibility of the system, and simultaneously, the structure of the output current estimation module is simpleUnder the condition of not increasing hardware cost, the dynamic response capability of the PFC output voltage can be improved by changing a software algorithm, and the system cost is favorably reduced.
Drawings
Fig. 1 is a schematic diagram of a topology structure of a boost-type digital PFC circuit in the prior art;
FIG. 2 is a dual-loop control block diagram of a boost-type digital PFC circuit in the prior art;
fig. 3 is a block diagram of a PFC control structure according to an embodiment of the present invention.
Description of reference numerals:
1-a PFC circuit; 11-an inductance; 12-a diode; 13-a switching tube; 14-capacitance; 2, a rectification circuit; 3-loading; 4-voltage outer loop module; 41-a first subtractor; 42-voltage loop regulator; 43-a first multiplier; 44-a first adder; 45-output voltage U0An input section; 46-given voltage UrefAn input section; 47-input Voltage UdAn input section; 5-current inner loop module; 51-a second subtractor; 52-current loop regulator; 53-input Current ILAn input section; 6-PWM module; 7-an output current estimation module; 71-a second multiplier; 72-a third subtractor; 73-a fourth subtractor; 74-differentiator.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and embodiments. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely illustrative of the invention and do not delimit the invention. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
A PFC control method, an apparatus, an air conditioner, and a computer-readable storage medium according to embodiments of the present invention are described in detail below with reference to the accompanying drawings.
As shown in fig. 1, a topology structure of a boost-type digital PFC circuit in the prior art includes an AC power supply, a rectifying circuit 2, a PFC circuit 1, and a load 3, where the PFC circuit 1 includes an inductor 11, a diode 12, a switching tube 13, and a capacitor 14, and a specific connection structure thereof is shown in fig. 1, and in the present invention, no improvement on the topology structure of the PFC circuit is involved, which is not described herein again.
As shown in fig. 2, a dual-loop control system of a boost PFC circuit in the prior art includes a voltage outer loop module 4, a current inner loop module 5 and a PWM module 6, where the voltage outer loop module 4 includes an output voltage U0Input unit 45 and predetermined voltage UrefInput 46 and input voltage UdInput 47 three signal inputs, of which the voltage U is output0An input voltage U as an output voltage of the PFC circuit 1dThe rectified output voltage obtained after the voltage output for the AC power supply passes through the rectifying circuit 2 is also the input voltage of the PFC circuit 1, U0And UdTypically by sampling by a voltage sampling circuit (not shown), said given voltage UrefIs a preset reference voltage. The voltage outer loop module 4 further includes a first subtractor 41, a voltage loop adjuster 42, and a first multiplier 43, wherein an input end of the first subtractor 41 is connected to the output voltage U respectively0 Input unit 45 and predetermined voltage UrefAn input unit 46, an output terminal of the first subtractor 41 is connected to an input terminal of a voltage loop adjuster 42, an output terminal of the voltage loop adjuster 42 is connected to an input terminal of the first multiplier 43, and the input voltage UdThe input part 47 is connected to the other input terminal of the first multiplier 43, and the output terminal of the first multiplier 43 is connected to the current inner loop module 5.
Specifically, the current inner loop module 5 comprises an input current ILAn input part 53 for inputting the current ILFor inputting the current in the inductor 11, the current inner loop module 5 further includes a second subtractor 51 and a current loop regulator 52, wherein the input ends of the second subtractor 51 are respectively connected to the input current ILThe input part 53 and the output end of the first multiplier 43, the output end of the second subtracter 51 is connected with the input end of the current loop regulator 52, the current loop regulator 52 is connected with the PWM module 6, the PWM module 6 generates a PWM waveform model according to the value output by the current loop regulator 52, and the PWM waveform signal controls the on-off of the switch tube 13.
The control principle of the Boost type digital PFC circuit in the prior art is as follows:
1, a given voltage U is set by the first subtracter 41refAnd the output voltage U of the PFC circuit 10Comparing, and outputting the difference value after being regulated by the voltage ring regulator 42;
2, the output value of the voltage loop regulator 42 and the input voltage U of the PFC circuit 1 are processed by a first multiplier 43dMultiplying to obtain the reference current I of the input currentref；
3, the current I of the inductor 11 is converted by the second subtracter 51LAnd a reference current IrefComparing, sending the comparison value to the PWM module 6 after passing through the current loop regulator 52 to generate a PWM waveform signal, controlling the on-off of the switch tube 13 by the PWM waveform signal, and further enabling the current I of the inductor 11LCan track the output voltage U of the rectifying circuit 2 welldThe waveform change of the power factor correction circuit greatly reduces current harmonic waves so as to achieve the purpose of improving the power factor.
As shown in fig. 2, in the prior art, at the output voltage U0Between the input unit 45 and the input terminal of the first subtractor 41, at the input voltage UdAn AD filter is disposed between the input portion 47 and the input end of the first multiplier 43, and in order to ensure that the harmonic content of the input current is low, the power frequency ripple twice as high as the output voltage needs to be limited to be very lowLAn AD filter is also provided between the input 53 and the input of the second subtractor 51, but the AD filter has a high bandwidth such that the inductor 11 has a current ILThe waveform of the voltage regulator can quickly track the rectified output voltage UdThe waveform of (a) changes.
Example 1
The present embodiment provides a PFC control method for controlling a PFC system, where the PFC system includes a PFC circuit device and a PFC control device, and the circuit device includes an AC power supply and a rectified currentThe PFC control device comprises a circuit 2, a PFC circuit 1 and a load 3, wherein the PFC control device comprises a voltage outer ring module 4, a current inner ring module 5, a PWM module 6 and an output current estimation module 7, and the voltage outer ring module 4 is used for outputting a reference current I to the current inner ring module 5refThe current inner ring module 5 is used for generating a reference current I according torefControlling the PWM waveform output by the PWM module 6, wherein the control method comprises the following steps:
estimating and obtaining the output current I of the load 30And applying the output current I0Injecting the voltage outer loop module 4, the voltage outer loop module 4 according to the output current I0Obtaining the reference current IrefFor fast response of the output voltage of the PFC circuit 1 when the load 3 varies.
Due to the output current I of the load 30Directly related to the variation of the load 3, when the load 3 suddenly changes, the output current I0An abrupt change will also occur, in which arrangement the output current I0Will directly result in the reference current IrefFurther causing the change of the PWM waveform, driving the on-off change of the switching tube 13, and finally causing the output voltage of the PFC circuit 1 to change rapidly, since the change is mainly caused by the output current I of the load 30Therefore, the low-pass filter is not influenced, the fast dynamic response of the output voltage of the PFC circuit 1 is realized, and the response speed of the system is greatly improved.
Specifically, the PFC circuit 1 is a boost type circuit, and includes an inductor 11, a diode 12, a switching tube 13, and a capacitor 14, as shown in fig. 1, and the following equations (1) and (2) are obtained according to kirchhoff's current law:
ID＝IL-IS (1)，
I0＝ID-IC (2)，
wherein, IDIs the current of the diode 12, ILIs the current of the inductor 11, ISIs the current of the switching tube 13, ICIs the current of the capacitor 14, I0Is the output current of the load 3.
The current of the capacitor 14 is calculated as equation (3):
where C is the capacitance of the capacitor 14,
for the derivative of the voltage of the capacitor 14 with respect to time, it should be noted that UcIs the output voltage of capacitor 14, which is also the output voltage of PFC circuit 1, i.e. Uc＝U0。
The relation between the average current flowing through the switching period of the switching tube 13 and the current of the inductor 11 is shown as formula (4):
IS＝IL×m (4)，
where m is the duty cycle.
The output current I can be obtained by bringing the above formulas (1), (3) and (4) into the formula (2)0The calculation formula of (2) is as follows:
wherein, ILIs the current of the inductor 11, m is the duty cycle, C is the capacitance of the capacitor 14,
the derivative of the capacitor 14 voltage with respect to time. Wherein IL、UcT is a detection value which can be realized by a system in the prior art, the capacitance value C of the capacitor 14 is a fixed quantity, the control algorithm of the duty ratio m in the PFC is a known quantity, the parameters are not difficult to obtain, only the algorithm is needed to be adjusted, and the hardware cost is not increased, so that the output current I can be conveniently obtained through the formula0So as to greatly improve the response speed of the output voltage of the PFC circuit 1 without increasing the hardware cost, so that the user can obtain better use experience.
Specifically, the control method provided by the invention comprises the following steps:
step S1, calculating and acquiring the output current I of the load 30And will output a current I0Multiplying by K0Then the voltage is output to the voltage outer ring module 4;
step S2, according to output current I, in the voltage outer loop module 40Calculating reference current I by correlationrefAnd applying the reference current IrefTo the current inner ring module 5;
step S3, according to the reference current I, in the current inner loop module 5refThe correlation calculation is carried out, and then the output value is transmitted to the PWM module 6;
step S4, the PWM module 6 generates a PWM waveform signal according to the output value of the current inner loop module 5, and the PWM waveform signal is used for controlling the on-off of the switch tube 13 in the PFC circuit 1;
wherein, K0The specific value is a preset value for the output current injection coefficient.
Through the steps, the on-off of the switch tube 13 in the PFC circuit 1 and the output current I of the load 3 are switched on and off0A correlation is made, the output current I being such that when the load 3 suddenly changes0Will also suddenly change, the output current I0Will directly result in the reference current IrefFurther causing the change of the PWM waveform, driving the on-off change of the switching tube 13, and finally causing the rapid change of the output voltage of the PFC circuit 1, since the change is mainly caused by the output current I of the load 30Therefore, the method is not influenced by a low-pass filter in the prior art, the fast dynamic response of the output voltage of the PFC circuit 1 is realized, and the response speed of the system is greatly improved.
In the present embodiment, the output current I in step S10Calculated according to the following formula:
wherein, ILIs the current of the inductor 11, m is the duty cycle, C is the capacitance of the capacitor 14,
the derivative of the capacitor 14 voltage with respect to time.
Further, the step S2 includes:
step S21, a given voltage U is setrefAnd the output voltage U of the PFC circuit 10Comparing, and outputting the difference value after being regulated by the voltage ring regulator 42;
a step S22 of adding the output value in the step S21 and the output value in the step S1 and outputting the result;
step S23, the output value in step S22 is compared with the input voltage UdMultiplying and outputting the result, wherein the output value is the reference current Iref；
Wherein the input voltage UdThe rectified output voltage obtained by passing the voltage output from the AC power supply through the rectifier circuit 2 is also the input voltage of the PFC circuit 1, and the output value of step S1 is I0×K0。
According to the steps, the output current I can be determined0Obtaining a reference current Iref。
Specifically, step S3 includes:
step S31, converting the reference current IrefAnd an input current ILAnd comparing, and outputting the difference value after being regulated by the current loop regulator 52.
The output value of the above step is I0The influence of the variation can rapidly cause the variation of the PWM waveform when the load 3 varies, thereby controlling the on/off of the switching tube 13 in the PFC circuit 1.
It should be noted that the voltage loop regulator 42 is an element in the voltage outer loop module 4, and the current loop regulator 52 is an element in the current inner loop module 5.
Example 2
The embodiment discloses a PFC control device, which is used to implement the PFC control method described in embodiment 1.
The PFC control device is used for controlling a PFC circuit device, and the PFC circuit device comprises an AC power supply, a rectifying circuit 2, a PFC circuit 1 and a PFC circuit connected in sequenceThe PFC circuit 1 includes a load 3, the PFC circuit 1 is a boost type circuit, and includes an inductor 11, a diode 12, a switching tube 13, and a capacitor 14, as shown in fig. 3, the PFC control device includes a voltage outer loop module 4, a current inner loop module 5, a PWM module 6, and an output current estimation module 7, the voltage outer loop module 4 is configured to output a reference current I to the current inner loop module 5refThe current inner ring module 5 is used for generating a reference current I according torefThe PWM module 6 is used for generating PWM waveforms according to output values of the current inner loop module 5, the PWM waveforms are used for controlling on-off of a switch tube 13 in the PFC circuit 1, and the output current estimation module 7 is used for estimating output current I of the load 30And applying the output current I0Injection into the voltage outer loop module 4 for the reference current IrefAnd (4) calculating.
It should be understood that the connection relationship of the components in the boost-type PFC circuit 1 is the prior art, and some embodiments thereof are shown in fig. 1 of the present application and will not be described herein again. Due to the output current I of the load 30Directly related to the variation of the load 3, when the load 3 suddenly changes, the output current I0Will also suddenly change, the PFC control device will output the current I0Directly resulting in the reference current I when changedrefThe change of the PWM waveform further causes the change of the PWM waveform, drives the on-off change of the switch tube 13, and finally causes the rapid change of the PFC output voltage, thereby greatly improving the response speed of the output voltage of the PFC circuit 1 and avoiding the influence of a low-pass filter.
Specifically, the voltage outer loop module 4 comprises an output voltage U0Input unit 45 and predetermined voltage UrefInput 46 and input voltage UdInput 47 three signal inputs, of which the voltage U is output0Is the output voltage of the PFC circuit 1, which is also the output voltage U of the capacitor CcInput voltage UdThe rectified output voltage obtained after the voltage output for the AC power supply has passed through the rectifying circuit 2, i.e. the U0And UdObtained by sampling with a voltage sampling circuit, the given voltage UrefTo preset a reference voltage, theThe voltage outer loop module 4 further comprises a first subtractor 41, a voltage loop adjuster 42, a first multiplier 43 and a first adder 44, wherein the input end of the first subtractor 41 is connected to the output voltage U respectively0Input unit 45 and predetermined voltage UrefAn input unit 46, wherein an output terminal of the first subtractor 41 is connected to an input terminal of a voltage loop regulator 42, an output terminal of the voltage loop regulator 42 is connected to one input terminal of the first adder 44, another input terminal of the first adder 44 is connected to an output terminal of the output current estimation module 7, an output terminal of the first adder 44 is connected to one input terminal of a first multiplier 43, and another input terminal of the first multiplier 43 is connected to an input voltage UdAn input 47, an output of the first multiplier 43 is connected to the current inner loop module 5.
In this embodiment, a specific control calculation method of the voltage outer loop module 4 is as follows:
1, a given voltage U is set by the first subtracter 41refAnd the output voltage U of the PFC circuit 10Comparing, and outputting the difference value after being regulated by the voltage ring regulator 42;
2, adding the output value of the voltage loop regulator 42 and the output value of the output current estimation module 7 by a first adder 44 and outputting;
3, the output value of the first adder 44 and the input voltage U of the PFC circuit 1 are added by the first multiplier 43dThe multiplied output is the reference current I of the input current inner loop module 5ref。
In the present embodiment, the current inner loop module 5 includes an input current ILAn input part 53 for inputting the current ILFor inputting the current in the inductor 11, the current inner loop module 5 further includes a second subtractor 51 and a current loop regulator 52, wherein the input ends of the second subtractor 51 are respectively connected to the input current ILAn input 53 and an output of the first multiplier 43, an output of the second subtractor 51 being connected to an input of the current loop regulator 52, an output of the current loop regulator 52 being connected to the PWM module 6.
In this embodiment, a specific control calculation method of the current inner loop module 5 is as follows:
the inductor 11 current I is fed through the second subtractor 51LAnd a reference current IrefComparing, outputting the comparison value after the comparison value is regulated by the current loop regulator 52, inputting the output value of the current loop regulator 52 into the PWM module 6 to generate a PWM waveform signal, controlling the on-off of the switching tube 13 by the PWM waveform signal, and further enabling the current I of the inductor 11LCan track the output voltage U of the rectifying circuit 2 welldThe waveform change of the power factor correction circuit greatly reduces current harmonic waves so as to achieve the purpose of improving the power factor.
In this embodiment, the output voltage U is0 Input unit 45 and input current ILThe input 53 and the output of the current loop regulator 52 are also connected to the input of the output current estimation module 7, respectively.
The output voltage U0Current I of inductor 11LAnd the duty cycle m output by the current loop regulator 52 as an input value of the output current estimation module 7 participates in the output current I0And (4) estimating.
Specifically, the output current estimation module 7 at least includes a second multiplier 71, a third subtractor 72, a fourth subtractor 73 and a differentiator 74, wherein the input end of the second multiplier 71 is connected to the input current ILAn input 53 and an output of the current loop regulator 52, an input of the second multiplier 71 is connected to an input of the third subtractor 72, and another input of the third subtractor 72 is connected to the input current ILAn input unit 53, an output terminal of the third subtractor 72 is connected to one input terminal of the fourth subtractor 73, another input terminal of the fourth subtractor 73 is connected to an output terminal of the differentiator 74, an output terminal of the fourth subtractor 73 is connected to an input terminal of the first adder 44, and an input terminal of the differentiator 74 is connected to the output voltage U0An input section 45.
In this embodiment, the specific control method of the output current estimation module 7 is as follows:
1, inputting a current I through the second multiplier 71LMultiplying the duty ratio m and outputting;
2, the input current I is converted into the output current by the third subtractor 72LComparing the difference value with the output value of the second multiplier 71 and outputting the difference value;
3 calculating the time derivative of the voltage of the capacitor 14 by means of said differentiator 74
Wherein U isc＝U0And will be
Multiplying by C to output, K in FIG. 3cRepresents the capacitance value C of the capacitor 14;
4, comparing the output value of the third subtractor 72 with the output value of the differentiator 74 through a fourth subtractor 73, and multiplying the difference by K0Rear output, K in FIG. 30For output current injection coefficient, K0Is a preset value.
The output current I can be obtained after calculation through the above elements0Is injected into the reference current IrefThe response speed of the output voltage of the PFC circuit 1 can be obviously improved, and the control response speed of the air conditioner is improved.
It will be appreciated that at the output voltage U0Between the input unit 45 and the input terminal of the first subtractor 41, at the input voltage UdAn AD filter is provided between the input part 47 and the input end of the first multiplier 43, and the output voltage U is output0After passing through a low-pass filter with a bandwidth of tens of hertz, the voltage enters the voltage loop regulator 42 and the output current estimation module 7 to participate in operation, and the input voltage UdFiltered and enters the voltage loop regulator 42 to participate in operation at the input current ILAn AD filter is also provided between the input unit 53 and the input terminal of the second subtractor 51, and the AD filter has a high bandwidth and the input current ILAfter being filtered, the filtered signal enters an output current estimation module 7 to participate in operation, specifically, the bandwidth selection of the three AD filters and the prior artThe same is not described herein again.
Example 3
The embodiment discloses an air conditioner, which comprises the PFC control device in the embodiment 2.
The air conditioner disclosed in the present embodiment includes a computer readable storage medium storing a computer program and a processor, and when the computer program is read and executed by the processor, the air conditioner implements the PFC control method according to embodiment 1.
The advantages of the air conditioner and the PFC control method according to embodiment 1 are the same as those of the prior art, and are not described herein again.
Example 4
The present embodiment discloses a computer-readable storage medium storing a computer program, which is read and executed by a processor to implement the PFC control method according to embodiment 1.
Although the present invention is disclosed above, the present invention is not limited thereto. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (12)
1. A PFC control method for controlling a PFC system, characterized in that the PFC system comprises PFC circuitry including a PFC circuit (1) and PFC control meansThe PFC control device comprises a load (3), the PFC control device comprises a voltage outer ring module (4), a current inner ring module (5) and a PWM module (6), the voltage outer ring module (4) is used for outputting a reference current I to the current inner ring module (5)refThe current inner loop module (5) is used for generating a reference current IrefControlling a PWM waveform output by the PWM module (6), the control method comprising:
estimating and obtaining the output current I of the load (3)0And applying the output current I0Injecting said voltage outer loop module (4), said voltage outer loop module (4) being dependent on said output current I0Obtaining the reference current IrefThe reference current IrefFor fast response of the PFC circuit (1) output voltage upon variations of the load (3).
2. The PFC control method of claim 1, wherein the control is performed according to the following steps:
step S1, calculating and acquiring the output current I of the load (3)0And will output a current I0And K0Multiplying and outputting the voltage to the voltage outer ring module (4);
step S2, according to output current I in the voltage outer loop module (4)0Calculating reference current I by correlationrefAnd applying the reference current IrefTo the current inner ring module (5);
step S3, according to the reference current I in the current inner loop module (5)refOutputting after correlation calculation, and transmitting an output value to a PWM module (6);
step S4, the PWM module (6) generates a PWM waveform signal according to the output value of the current inner loop module (5), and the PWM waveform signal is used for controlling the on-off of a switch tube (13) in the PFC circuit (1);
wherein, K0The specific value is a preset value for the output current injection coefficient.
3. The PFC control method of claim 2, wherein the output current I in step S1 is0Calculated according to the following formula:
wherein, ILIs the current of an inductor (11) in the PFC circuit (1), m is the duty ratio, C is the capacitance value of a capacitor (14) in the PFC circuit (1),
is the derivative of the voltage of a capacitor (14) in a PFC circuit (1) with respect to time.
4. The PFC control method of claim 2, wherein the step S2 includes:
step S21, a given voltage U is setrefAnd an output voltage U0Comparing, and outputting the difference value after being regulated by a voltage ring regulator (42);
a step S22 of adding the output value in the step S21 and the output value in the step S1 and outputting the result;
step S23, the output value in step S22 is compared with the input voltage UdMultiplying and outputting the result, wherein the output value is the reference current Iref；
Wherein the input voltage UdIs the input voltage of the PFC circuit (1), the output voltage U0The output value of step S1 is I for the output voltage of PFC circuit (1)0×K0。
5. The PFC control method of claim 2, wherein the step S3 includes:
step S31, converting the reference current IrefAnd an input current ILComparing, and outputting the difference value after being regulated by a current loop regulator (52);
wherein the input current ILIs the current of an inductor (11) in the PFC circuit (1).
6. A PFC control device for controlling a PFC circuit arrangement comprising a PFC circuit (1) and a load (3), the PFC control device comprising:
a voltage outer ring module (4) for outputting a reference current I to the current inner ring module (5)ref；
A current inner loop module (5) for dependent on a reference current IrefControlling the PWM waveform output by the PWM module (6);
the PWM module (6) is used for generating a PWM waveform according to the output value of the current inner ring module (5), and the PWM waveform is used for controlling the on-off of a switch tube (13) in the PFC circuit (1);
an output current estimation module (7) for estimating an output current I of the load (3)0And applying the output current I0Injection into the voltage outer loop module (4) for the reference current IrefAnd (4) calculating.
7. The PFC control device of claim 6, wherein the voltage outer loop module (4) comprises an output voltage U0An input unit (45) and a predetermined voltage UrefInput unit (46) and input voltage UdThe three signal input parts of the input part (47) further comprise a first subtracter (41), a voltage loop regulator (42), a first multiplier (43) and a first adder (44), wherein the input end of the first subtracter (41) is respectively connected with an output voltage U0An input unit (45) and a predetermined voltage UrefAn input (46), the output of the first subtractor (41) is connected to the input of a voltage loop regulator (42), the output of the voltage loop regulator (42) is connected to one input of the first adder (44), the other input of the first adder (44) is connected to the output of the output current estimation module (7), the output of the first adder (44) is connected to one input of a first multiplier (43), the other input of the first multiplier (43) is connected to the input of an input voltage UdAn input (47), the output of the first multiplier (43) being connected to the current inner loop module (5);
wherein the output voltage U0For the output voltage of the PFC circuit (1), the input voltage UdA given voltage U is an input voltage of the PFC circuit (1)refIs a preset reference voltage.
8. The PFC control device of claim 7, wherein the current inner loop module (5) comprises an input current ILThe input part (53), the current inner loop module (5) further comprises a second subtracter (51) and a current loop regulator (52), wherein the input ends of the second subtracter (51) are respectively connected with the input current ILAn input (53) and an output of a first multiplier (43), an output of the second subtractor (51) being connected to an input of the current loop regulator (52), an output of the current loop regulator (52) being connected to a PWM module (6);
wherein the input current ILIs the current of an input inductor (11) in the PFC circuit (1).
9. The PFC control device of claim 8, wherein the output voltage U is0An input unit (45) and an input current ILThe input (53) and the output of the current loop regulator (52) are also connected to the input of the output current estimation module (7), respectively.
10. The PFC control device according to claim 9, characterized in that the output current estimation block (7) comprises at least a second multiplier (71), a third subtractor (72), a fourth subtractor (73) and a differentiator (74), the inputs of the second multiplier (71) being connected to the input current I, respectivelyLAn input (53) and an output of the current loop regulator (52), an input of the second multiplier (71) being connected to one input of the third subtractor (72), another input of the third subtractor (72) being connected to the input current ILAn input unit (53), wherein an output terminal of the third subtractor (72) is connected to one input terminal of the fourth subtractor (73), another input terminal of the fourth subtractor (73) is connected to an output terminal of the differentiator (74), and an input terminal of the differentiator (74) is connected to the output voltage U0And an input unit (45), wherein an output terminal of the fourth subtractor (73) is connected to an input terminal of the first adder (44).
11. An air conditioner comprising a computer readable storage medium storing a computer program and a processor, the computer program being read and executed by the processor to implement a PFC control method according to any one of claims 1 to 5.
12. A computer-readable storage medium, characterized in that it stores a computer program which, when read and executed by a processor, implements a PFC control method according to any one of claims 1 to 5.
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