Power factor compensation circuit and household appliance

Abstract

The invention discloses a power factor compensation circuit and a household electrical appliance, the circuit comprises a switching device, a load circuit and a controller, the controller is configured to obtain a duty ratio value of a pulse width adjustment signal, and calculate a duty ratio value threshold according to a power supply voltage phase and a preset attenuation coefficient; according to the duty ratio value threshold value, carrying out limited shrinkage correction on the duty ratio value; and controlling the switching device to perform periodic on-off according to the duty ratio value after the limiting and shrinking correction. According to the technical scheme, when the power factor compensation circuit is started, the power factor compensation circuit cannot cause current overload.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power factor compensation circuit, and particularly relates to a power factor compensation circuit and a household appliance. BACKGROUND

[0002] Many power loads in the power grid belong to inductive loads, and these inductive loads need to absorb useful power and useless power from the power system during operation. Therefore, a common treatment method is to use power factor compensation. Power factor compensation, i.e., by installing a parallel capacitor module in the power grid, a reactive power compensation device can provide compensation for the reactive power consumed by the inductive load, thereby reducing the reactive power provided by the power grid power supply and in the transmission line process.

[0003] When the power factor compensation circuit starts, the load voltage will suddenly change. If no measures are taken during the starting stage, an excessive current impact caused by the bus voltage mutation will be easily caused, and in a serious case, there is a risk of damaging electronic components.

[0004] Therefore, when the power factor compensation circuit starts, avoiding excessive current impact is a technical problem that needs to be solved at present. SUMMARY

[0005] The purpose of the present application is to enable the power factor compensation circuit not to cause current overload when the power factor compensation circuit starts.

[0006] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0007] According to one aspect of an embodiment of the present application, a power factor compensation circuit is provided, the circuit comprising:

[0008] a switching device, a first end of the switching device being electrically connected to a first end of a power supply through an inductive module, a second end of the switching device being electrically connected to a second end of the power supply; a load circuit, a first end of the load circuit being connected to the first end of the switching device, a second end of the load circuit being connected to the second end of the switching device; a controller, the controller being electrically connected to a control end of the switching device, for inputting a pulse width adjustment signal to the control end of the switching device; the controller is configured to: obtain a duty cycle value of the pulse width adjustment signal, and calculate a duty cycle value threshold according to a power supply voltage phase and a preset attenuation coefficient; limit and correct the duty cycle value according to the duty cycle value threshold; control the switching device to periodically turn on and off according to the duty cycle value after the limit and correction.

[0009] In the embodiment of the present application, when the power factor compensation circuit is started, the duty cycle value is calculated according to the current and voltage information in the power grid, and the duty cycle value is not corrected by the circuit operation effect for multiple times, so it is inevitable to frequently cause the current compensation value to be too large, impact the electronic components in the power grid, and cause damage to the electronic components. Therefore, the embodiment of the present application limits and corrects the calculated duty cycle value to a certain extent, so that the duty cycle value is below a certain threshold when in use, thereby avoiding the situation that the obtained duty cycle value in the starting stage causes the load voltage to be too large and the current to be too large.

[0010] In an embodiment of the present application, before the duty cycle value is obtained and the duty cycle value threshold is calculated according to the power supply voltage phase and the preset attenuation coefficient, the method further comprises: if the attenuation coefficient is used for the first time, directly using the attenuation coefficient to calculate the duty cycle value threshold; if the use frequency of the attenuation coefficient is greater than 1, obtaining an attenuation variable of the attenuation coefficient, and updating the attenuation coefficient according to the attenuation variable.

[0011] In the process of correcting the obtained duty cycle value according to the preset attenuation coefficient, for the first use, the attenuation coefficient is directly used to calculate the duty cycle value threshold, and for the non-first use, the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the attenuation variable. In this way, the attenuation coefficient is gradually reduced, the attenuation of the duty cycle value is gradually reduced, that is, the limitation and correction of the duty cycle value are gradually reduced, and after the starting stage, the limitation of the duty cycle value is removed, and the switching device can be normally controlled according to the duty cycle value. Only the limitation of the power factor compensation circuit in the starting stage is realized, and the normal use of the power factor compensation circuit in the running stage is not affected.

[0012] In an embodiment of the present application, the updating of the attenuation coefficient according to the attenuation variable comprises: obtaining an attenuation variable of the attenuation coefficient; if the attenuation coefficient is less than or equal to the attenuation coefficient variable, updating the attenuation coefficient to zero; and if the attenuation coefficient is greater than the attenuation coefficient variable, taking the difference between the attenuation coefficient and the attenuation coefficient variable as the updated attenuation coefficient.

[0013] In the embodiment of the present application, the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the size relationship between the attenuation variable and the attenuation coefficient. It is ensured that the attenuation coefficient is not negative, that is, the negative limitation of the duty cycle value is avoided, that is, the duty cycle value will not be higher than the theoretical peak value, and then the situation that the current compensation value is too large and causes damage to the electronic components in the power grid is avoided when the power factor compensation circuit is running.

[0014] In an embodiment of the present application, the attenuation variable of the attenuation coefficient comprises: taking the quotient between the power factor compensation circuit starting time and the control method running period as the attenuation times; and taking the ratio between the attenuation variable and the attenuation times as the attenuation variable.

[0015] In an embodiment of the present application, first, the quotient between the power factor compensation circuit starting time and the control method running period is taken as the attenuation times, and finally, the ratio between the attenuation variable and the attenuation times is taken as the attenuation variable. Through the above calculation method, it is ensured that the attenuation coefficient only limits the obtained duty cycle value in the starting stage of the power factor compensation circuit, and the limitation on the obtained duty cycle value is removed when the power factor compensation circuit enters the running stage, so that the power factor compensation circuit can normally run. This further avoids the influence of the attenuation variable on the duty cycle value when the power factor compensation circuit is in the running stage, which leads to poor running effect of the power factor compensation circuit. It realizes the limitation and correction only in the starting stage of the power factor compensation circuit, without affecting the normal running of the power factor compensation circuit.

[0016] In an embodiment of the present application, the duty cycle value threshold is calculated according to the power supply voltage phase and the preset attenuation coefficient, comprising: calculating the duty cycle value threshold according to the updated attenuation coefficient and the power supply voltage phase through the following formula:

[0017] D m =1-K d *|sinθ s |

[0018] Wherein, the D m is the duty cycle value threshold, K d is the attenuation coefficient, and sinθ s is the power supply voltage phase.

[0019] In an embodiment of the present application, the duty cycle value threshold is calculated based on the set formula. As can be seen from the formula, the duty cycle value threshold is calculated based on the power supply voltage phase and the attenuation coefficient, which can further limit the duty cycle value to obtain the duty cycle value threshold. And the duty cycle value threshold and the duty cycle value have the same maximum value, which is 1. This makes the limitation of the duty cycle value threshold on the duty cycle value always within a reasonable range, further ensuring the rationality of the limitation on the duty cycle value. The limitation effect on the duty cycle value is more ideal, which ensures that the power factor compensation circuit will not be damaged due to excessive current when it is in the starting stage.

[0020] In an embodiment of the present application, the limiting and correcting the duty cycle value according to the duty cycle value threshold comprises: taking the smaller one of the duty cycle value and the duty cycle value threshold as the limited and corrected duty cycle value; and taking any one of the duty cycle value and the duty cycle value threshold as the limited and corrected duty cycle value if the duty cycle value is the same as the duty cycle value threshold.

[0021] In an embodiment of the present application, the limiting and correcting the duty cycle value according to the duty cycle value threshold comprises: taking the smaller one of the duty cycle value and the duty cycle value threshold as the limited and corrected duty cycle value; and taking any one of the duty cycle value and the duty cycle value threshold as the limited and corrected duty cycle value if the duty cycle value is the same as the duty cycle value threshold.

[0022] In an embodiment of the present application, the obtaining the duty cycle value of the pulse width adjustment signal comprises: calculating the duty cycle value according to a load voltage of the load circuit, a phase of an input current of the inductor module, and a voltage instruction indicating a required voltage of the load circuit.

[0023] In an embodiment of the present application, the duty cycle value is calculated according to a load voltage of the load circuit, a phase of an input current of the inductor module, and a voltage instruction indicating a required voltage of the load circuit. The duty cycle value is used to control the on-off of the switching device periodically, so as to control the size and phase of the input current, and make the phase of the current waveform and the voltage waveform consistent, thereby increasing the power utilization.

[0024] In an embodiment of the present application, the calculating the duty cycle value according to the voltage instruction indicating the required voltage of the load circuit, the load voltage of the load circuit, and the phase of the input current of the inductor module comprises:

[0025] The required amplitude of the input current is corrected according to the difference between the voltage instruction and the load voltage; the required phase of the input current is corrected according to the phase information of the load voltage and the phase information of the input current; and the duty cycle value is calculated according to the required amplitude of the input current and the required phase of the input current.

[0026] In the embodiments of the present application, according to the difference between the voltage instruction and the load voltage, the error between the current load voltage and the voltage indicated by the voltage instruction can be obtained, that is, the size of the voltage value required by the load voltage can be determined according to the difference between the voltage instruction and the load voltage. Since the purpose of the power factor compensation circuit is to make the voltage waveform and the current waveform coincide in phase, and there is a physical relationship between the voltage and the current, according to the size of the voltage value required by the load voltage, the required amplitude of the input current can be determined, and then according to the phase information of the load voltage and the phase information of the input current, the required phase of the input current can be determined, and the duty cycle value is calculated according to the required amplitude and the required phase of the input current. The duty cycle value is controlled by the periodic on-off of the switch device, so that the amplitude and phase of the input current tend to the required phase and amplitude of the input current. In this way, the duty cycle value can be obtained more quickly and directly.

[0027] In an embodiment of the present application, the power supply is an alternating current power supply, and the power factor compensation circuit further comprises a rectification module connected to the alternating current power supply, for converting alternating current provided by the alternating current power supply into direct current, and the first end of the switch device is electrically connected to the first output end of the rectification module through an inductance module, and the second end of the switch device is electrically connected to the second output end of the rectification module.

[0028] In the embodiments of the present application, when the power supply is an alternating current power supply, the power factor compensation circuit further comprises a rectification module, which is used to convert the alternating current generated by the alternating current power supply into periodic direct current. This makes the power factor compensation circuit in the embodiments of the present application can be universally applied to different circuits, greatly increasing the scope of application of the present application.

[0029] According to the second aspect of the embodiments of the present application, the present application is a household appliance, comprising a variable frequency motor; and the power factor compensation circuit according to any one of the above embodiments, wherein the variable frequency motor is in the load circuit, and the power factor compensation circuit is used for controlling the variable frequency motor. In the embodiments of the present application, the above technical solution can be applied to any household appliance with a variable frequency motor, reducing the useless power generated by the variable frequency motor during operation, and increasing the useful power of the variable frequency motor, so that the application of electric energy by the household appliance is more efficient, and the energy-saving experience effect of the household appliance is increased for the user.

[0030] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0031] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application. It is apparent that the drawing in the following description is only some embodiments of the application, and other drawings can be obtained by those of ordinary skill in the art without creative labor on the basis of these drawings.

[0033] Figure 1 A circuit diagram of a power factor compensation circuit according to an embodiment of the application is shown.

[0034] Figure 2 A schematic diagram of a power factor compensation circuit according to an embodiment of the application is shown.

[0035] Figure 3 A flow chart of controlling a power factor compensation circuit according to an embodiment of the application is shown.

[0036] Figure 4 A flow chart of determining a decay variable before calculating a duty ratio value threshold according to an embodiment of the application is shown.

[0037] Figure 5 A flow chart of updating a decay coefficient according to a decay variable according to an embodiment of the application is shown.

[0038] Figure 6 A flow chart of obtaining a decay variable of a decay coefficient according to an embodiment of the application is shown.

[0039] Figure 7 A flow chart of limiting and correcting a duty ratio value according to a numerical relationship between a duty ratio value threshold and a duty ratio value according to an embodiment of the application is shown.

[0040] Figure 8 A flow chart of calculating a duty ratio value according to a load voltage of a load circuit, a phase of an input current of an inductive module, and a voltage command indicating a required voltage of the load circuit according to an embodiment of the application is shown.

[0041] Figure 9 A schematic diagram of a power factor compensation circuit according to another embodiment of the application is shown.

[0042] Explanation of reference signs:

[0043] 1: power supply (AC power supply);

[0044] 2: inductive module;

[0045] 3: switching device;

[0046] 4: load circuit;

[0047] 41: diode;

[0048] 42: capacitor module;

[0049] 43: energy consumption module; DETAILED DESCRIPTION

[0050] Example implementations are now described with reference to the following drawings. The example implementations, however, can be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example implementations to those skilled in the art.

[0051] Moreover, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the

[0052] The block diagrams in the drawings show only the functionality of the example implementations and do not imply any particular physical or architectural arrangement of the example implementations. For example, functions shown as discrete blocks in the example implementations can be implemented in monolithic form with separate circuits or in integrated form with shared circuits. The example implementations shown in the drawings are not exhaustive and do not limit the scope of the example implementations to the one or more specific arrangements and instrumentality shown in the drawings.

[0053] The flow diagrams shown in the drawings are examples only and are not necessarily to scale. Also, the flow diagrams can not include all of the steps or options discussed in the description of the example implementations. For example, one or more of the steps can be combined or partially combined with other steps, and some steps can be performed at the same time as other steps. Also, the order of the steps can be changed.

[0054] In the example implementations, the term "module" or "unit" refers to a computer program or a part of a computer program with a predetermined function, and works together with other related parts to achieve a predetermined goal, and can be implemented entirely or partially using software, hardware (such as a processing circuit or a memory), or a combination thereof. Similarly, one processor (or multiple processors or memories) can be used to implement one or more modules or units. In addition, each module or unit can be a part of an overall module or unit that includes the functions of the module or unit.

[0055] Reference will now be made to Figure 1 , Figure 1 A circuit diagram of a power factor compensation circuit according to an embodiment of the present application is shown. As shown in FIG. 1, the power factor compensation circuit includes a rectifier 10, a capacitor module 20, a diode 41, an energy consumption module 30, and a power factor compensation module 40.Figure 1 As shown, the power factor compensation circuit includes an AC power source 1. The power factor compensation circuit includes an inductor module 2. The power factor compensation circuit includes a switching device 3. The power factor compensation circuit includes a load circuit 4.

[0056] The first end of the switching device 3 is electrically connected to the first end of the power source 1 through the inductor module 2, and the second end of the switching device 3 is electrically connected to the second end of the power source 1. The first end of the load circuit 4 is connected to the first end of the switching device 3, and the second end of the load circuit 4 is connected to the second end of the switching device 3.

[0057] Please refer to Figure 2 , Figure 2 A schematic diagram of the power factor compensation circuit according to the embodiment of the present application is shown. As shown, Figure 2 The load circuit 4 includes a diode 41. The load circuit 4 includes a capacitor module 42. The load circuit 4 includes a power consumption module 43. As to how to adjust the input current size and the input current phase by the duty cycle value, the input current refers to the current flowing to the power source through the load circuit 43 or the switching device 3.

[0058] When the switching device 3 is closed, a short circuit is formed, the input current instantaneously becomes large, flows through the inductor module 2, and the magnetic field generated by the inductor module stores a part of the energy, that is, a part of the electric energy is retained, and then the input current flows back to the power source without passing through the load circuit 4.

[0059] When the switching device 3 is opened, first, the power source voltage is stably output, and the inductor module 2 also generates a voltage in the same direction, generating a current that flows to the load circuit together with the current generated by the power source, that is, flows to the load and the capacitor module 42. It needs to be clear that at this time, only when the voltage on the left side of the diode 41 is greater than the voltage on the right side of the diode 41, the current can flow. At this time, the capacitor module 42 starts to charge, and when the voltage on the left side of the diode 41 is less than the voltage on the right side of the diode 41, the capacitor module 42 starts to discharge, that is, starts to supply power to the power consumption module 43. Through the frequent discharge of the capacitor module 42, the voltage fluctuation supplied to the power consumption module 43 will be greatly reduced.

[0060] When the switching device 3 is frequently turned on and off, the input current is pulled up and supplied to the load module through the inductor module 3 and the capacitor module 41, thereby playing a role of power factor compensation and voltage boosting. Similarly, by this method, the phase of the current can also be adjusted to keep consistent with the phase of the voltage. The duty cycle value is used to define the on-off time ratio of the switching device 3 in a period, and the compensation current size is proportional to the duty cycle value. The larger the duty cycle value, the longer the switching device 3 is connected in a period. The on-off period is determined according to the voltage, the load circuit and the current.

[0061] The control scheme of the power factor compensation circuit mainly adopts the double closed-loop control of voltage outer loop and current inner loop. The function of the current inner loop is to force the input current to track the waveform of the input voltage, which is a sine waveform; the function of the voltage outer loop is to keep the output voltage at a level higher than the peak value of the input voltage, and can also stabilize the output voltage.

[0062] Please refer to Figure 3 , Figure 3 A flow chart of controlling the power factor compensation circuit according to an embodiment of the present application is shown. The steps of the controller control in the power factor compensation circuit of an embodiment provided by the present application include:

[0063] In step S310, the duty cycle value of the pulse width adjustment signal is obtained, and the duty cycle value threshold is calculated according to the power supply voltage phase and the preset attenuation coefficient;

[0064] In step S320, the duty cycle value is limited and corrected according to the duty cycle value threshold;

[0065] In step S330, the switch device is controlled to periodically turn on and off according to the limited and corrected duty cycle value.

[0066] The above three steps will be described in detail below.

[0067] In step S310, when the power factor compensation circuit is just started, the current is not compensated yet, and the power factor compensation circuit calculates the duty cycle value according to the existing voltage information and current information. In this process, since the current is smaller than the ideal state current, the power factor compensation circuit will determine that the compensation current needs to be increased at this time according to the current size, and thus the duty cycle value will become larger. It cannot be used directly, because it will cause the current after compensation by the power factor compensation circuit to be over-limit, which will damage the electronic components in the power grid. Therefore, the duty cycle value obtained during the starting stage of the power factor compensation circuit is limited to obtain a corrected duty cycle value, and the switch device 3 is controlled to periodically turn on and off by the required duty cycle limited corrected duty cycle value, so as to avoid causing the current to be over-limit. The duty cycle value is obtained at this time.

[0068] It should be noted that the size of the attenuation coefficient is in direct proportion to the limiting effect on the duty cycle value. The attenuation coefficient is greater than zero, which limits the duty cycle value, so that the duty cycle value threshold is smaller than the peak value that the duty cycle value can reach. The attenuation coefficient is less than zero, which amplifies the duty cycle value, so that the duty cycle value threshold is greater than the peak value that the duty cycle value can reach. The attenuation coefficient is equal to zero, which does not limit the duty cycle value, so that the duty cycle value threshold is equal to the peak value that the duty cycle value can reach.

[0069] In step S320, the duty cycle value is limited and corrected according to the numerical relationship between the duty cycle value threshold and the duty cycle value, so that the compensation current obtained by the corrected duty cycle value will not cause damage to the electronic components due to over-limit current.

[0070] Referring to Figure 4 , Figure 4 A flow chart for determining the attenuation variable before calculating the duty cycle value threshold according to an embodiment of the present application is shown. The embodiment of the present application provides steps for determining the attenuation variable before calculating the duty cycle value threshold, including:

[0071] In step S401, if the attenuation coefficient is used for the first time, the attenuation coefficient is directly used to calculate the duty cycle value threshold.

[0072] In step S402, if the number of times of using the attenuation coefficient is greater than 1, the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the attenuation variable.

[0073] The above two steps are described in detail below.

[0074] In step S401, since the obtained duty cycle value cannot be limited all the time, the obtained duty cycle value needs to be limited gradually, and therefore the attenuation coefficient needs to be variable. If the attenuation coefficient is used for the first time, the attenuation coefficient is directly used to calculate the duty cycle value threshold.

[0075] In step S402, in the embodiment of the present application, if the number of times of using the attenuation coefficient is greater than 1, the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the attenuation variable.

[0076] When the obtained duty cycle value is corrected according to the preset attenuation coefficient, for the first time of use, the attenuation coefficient is directly used to calculate the duty cycle value threshold, and for the time of use other than the first time, the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the attenuation variable. In this way, the attenuation coefficient is gradually reduced, so that the attenuation of the duty cycle value gradually decreases, that is, the limitation and correction of the duty cycle value is gradually reduced. After the start-up stage, the limitation of the duty cycle value is also removed, and the switching device can be normally controlled according to the duty cycle value to perform periodic on-off. Only the limitation of the start-up stage of the power factor compensation circuit is realized, and the normal use of the power factor compensation circuit in the running stage is not affected.

[0077] Referring to Figure 5 , Figure 5 A flow chart for updating the attenuation coefficient according to the attenuation variable according to an embodiment of the present application is shown. The embodiment of the present application provides steps for updating the attenuation coefficient according to the attenuation variable, including:

[0078] In step S501, the attenuation variable of the attenuation coefficient is obtained.

[0079] Step S502, if the attenuation coefficient is less than or equal to the attenuation variable, then update the attenuation coefficient to zero;

[0080] Step S503, if the attenuation coefficient is greater than the attenuation variable, then the difference between the attenuation coefficient and the attenuation variable is taken as the updated attenuation coefficient.

[0081] The above three steps are described in detail below.

[0082] It should be clear that the size of the attenuation coefficient is directly proportional to its limiting effect on the duty cycle value. The attenuation coefficient is greater than zero, which limits the duty cycle value, so that the duty cycle value threshold is less than the peak value that the duty cycle value can reach. The attenuation coefficient is equal to zero, which does not limit the duty cycle value, so that the duty cycle value threshold is equal to the peak value that the duty cycle value can reach. The attenuation coefficient is less than zero, so that the duty cycle value threshold is greater than the peak value that the duty cycle value can reach, but based on the above three steps, even if the attenuation coefficient is less than zero, the duty cycle value threshold is greater than the peak value that the duty cycle value can reach, it will not make the duty cycle value larger, that is, after the attenuation variable reaches zero, it will not limit the duty cycle value, that is, even if the method is executed during the operation stage of the power factor compensation circuit, it will not affect the effect of the power factor compensation circuit, further ensuring the technical effect of limiting only the start-up stage of the power factor compensation circuit.

[0083] In step S501, the attenuation variable of the attenuation coefficient is first obtained, which is used to change the attenuation coefficient. The attenuation variable can be a constant value or a variable value that changes according to the voltage and current information in the power grid.

[0084] For example, in an embodiment of the present application, the attenuation variable has three types: the first is the normal type (the attenuation coefficient is greater than zero, which reduces the limitation on the duty cycle value), the second is the protection type (the attenuation variable is equal to zero, which maintains the limitation on the duty cycle value), and the third is the abnormal type (the attenuation variable is less than zero, which increases the limitation on the duty cycle value).

[0085] When the voltage or current in the power grid is below a dangerous threshold, the dangerous threshold refers to a current value or voltage value that is too large in the power grid and can cause damage to electronic components in the power grid, the attenuation coefficient is updated using a normal type of attenuation variable, if the normal type of attenuation variable is a constant selected according to the use sequence, then according to the use sequence of the attenuation variable, the next attenuation variable is continuously selected as the updated attenuation variable to update the attenuation coefficient. If the normal type of attenuation variable is a constant, then the constant attenuation variable is continuously used as the updated attenuation variable to update the attenuation coefficient. If the normal type of attenuation variable is an interval, each interval corresponds to a set interval voltage value and a current value, then according to the current voltage value and current value, the attenuation variable is selected as the updated attenuation variable to update the attenuation coefficient.

[0086] When the current or voltage in the power grid is in a preset dangerous interval, the preset dangerous interval refers to an upper limit of the voltage or current in the power grid, and a current value interval or voltage value interval that is too large can cause damage to electronic components in the power grid. The attenuation variable is assigned a value of 0 (i.e., a protection type of attenuation variable) as the updated attenuation variable to update the attenuation coefficient, in order to prevent the attenuation variable from being too large, causing the limit of the duty cycle value to be too small, and thus causing the current to be over-limited and the electronic components in the power grid to be damaged.

[0087] If the limited and corrected duty cycle value is used to control the on-off of the switching device, and the current or voltage in the power grid exceeds or reaches the dangerous threshold, then an abnormal type of attenuation variable is used to update the attenuation coefficient.

[0088] When the voltage or current in the power grid exceeds the dangerous threshold, then according to the size of the voltage or current in the power grid exceeding the dangerous threshold, the corresponding abnormal attenuation variable (the abnormal attenuation variable is a negative value) is selected as the updated attenuation variable to update the attenuation coefficient. If the abnormal type of attenuation variable is a constant, then the constant abnormal type of attenuation variable is continuously used as the updated attenuation variable to update the attenuation coefficient. If the abnormal type of attenuation variable is an interval, each interval corresponds to a set interval voltage value and a current value, then according to the voltage value and current value, the abnormal type of attenuation variable is selected as the updated attenuation variable to update the attenuation coefficient.

[0089] Each time the attenuation variable is updated, the type of attenuation coefficient needs to be determined, and the attenuation coefficient is determined according to the current and voltage in the power grid. For example, if the current or voltage in the power grid is still in the preset dangerous interval next time, then the protection type of attenuation coefficient is continuously used. If the current or voltage in the power grid is less than the dangerous threshold next time, then the normal type of attenuation coefficient is continuously used to update the attenuation variable according to the sequence.

[0090] It is also necessary to make clear that the danger threshold can be preset or obtained from the parameters of various electronic components in the power grid and the environmental parameters such as temperature and humidity and light intensity of the current power grid.

[0091] For example, the maximum load current that the electronic component with the lowest intensity can bear is calculated as the danger threshold according to the parameters of the electronic component with the lowest intensity in the power grid and the environmental parameters. In an embodiment of the present application, the product of the theoretical load current of the electronic component and the environmental parameters is taken as the maximum current that the electronic component can bear, which is taken as the danger threshold. In another embodiment of the present application, the product of the maximum current that the electronic component with the lowest intensity can bear and a safety factor (the safety factor is greater than 0 and less than 1) is taken as the danger threshold, so as to avoid damaging the electronic component with the lowest intensity to the greatest extent.

[0092] Since the number of times of updating the attenuation coefficient is limited, three types of attenuation variables corresponding to each time of updating the attenuation coefficient are set, and different attenuation coefficients are selected and used according to different situations. After the number of times of updating is completed, the power factor compensation circuit starting stage is ended.

[0093] Please refer to Figure 6 , Figure 6 The flow chart of obtaining the attenuation variable of the attenuation coefficient according to an embodiment of the present application is shown. The embodiment of the present application provides an embodiment of the step S501 of obtaining the attenuation variable of the attenuation coefficient, which comprises:

[0094] In step S601, the quotient between the power factor compensation circuit starting duration and the control method running period is taken as the attenuation number of times;

[0095] In step S602, the ratio of the attenuation variable to the attenuation number of times is taken as the attenuation variable.

[0096] The above two steps are described in detail as follows.

[0097] In step S601, the quotient between the power factor compensation circuit starting duration and the control method running period is taken as the attenuation number of times. That is, the number of times of limiting the duty cycle value in the power factor compensation circuit is determined.

[0098] In step S602, the attenuation variable is determined according to the attenuation number of times, and the ratio of the attenuation variable to the attenuation number of times is taken as the attenuation variable, so as to ensure that the entire limitation can be completed in the power factor compensation circuit starting stage, and the power factor compensation circuit can be limited in the running stage and normally run.

[0099] In the embodiment of the present application, the quotient between the power factor compensation circuit starting time length and the control method running period is first taken as the attenuation number, and finally the ratio between the attenuation variable and the attenuation number is taken as the attenuation variable. Through the above calculation method, it is ensured that the attenuation coefficient only limits the obtained duty cycle value in the starting stage of the power factor compensation circuit, and the limitation on the obtained duty cycle value is released when the power factor compensation circuit enters the running stage, so that the power factor compensation circuit can normally run. This further avoids the influence of the attenuation variable on the duty cycle value when the power factor compensation circuit is in the running stage, resulting in poor running effect of the power factor compensation circuit. The limitation correction is only realized in the starting stage of the power factor compensation circuit, and the normal running of the power factor compensation circuit is not affected.

[0100] In step S502, since the calculation method of the duty cycle value threshold is the peak value of the duty cycle value minus the product of the attenuation coefficient and the attenuation value, the attenuation value is greater than zero. Therefore, in order to ensure that the attenuation coefficient can always realize the positive limitation of the duty cycle value under normal circumstances, that is, the calculated duty cycle value threshold is in the interval of 0-1, if the attenuation coefficient is less than or equal to the attenuation coefficient variable at this time, the attenuation coefficient is updated to zero. Because if the attenuation coefficient is not updated to zero at this time, the attenuation coefficient will be negative, which will make the duty cycle value threshold greater than 1, which will have no limiting effect on the duty cycle value, and instead may amplify the duty cycle value, increasing the risk of current overlimit.

[0101] In step S503, if the attenuation coefficient is greater than the attenuation coefficient variable, the difference between the attenuation coefficient and the attenuation coefficient variable is taken as the updated attenuation coefficient.

[0102] In the embodiment of the present application, the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the size relationship between the attenuation variable and the attenuation coefficient. It is ensured that the attenuation coefficient is not negative, that is, the negative limitation on the duty cycle value is avoided, that is, the duty cycle value will not be higher than the theoretical peak value, and further, the current compensation value is too large when the power factor compensation circuit runs, which causes the damage of electronic components in the power grid caused by current overlimit.

[0103] In an embodiment of the present application, the duty cycle value threshold is calculated according to the updated attenuation coefficient and the power supply voltage phase through the following formula:

[0104] D m =1-K d *|sinθ s |

[0105] Wherein, D m is the duty cycle value threshold, K d is the attenuation coefficient, and sinθ s is the power supply voltage phase.

[0106] In the embodiment of the present application, the duty cycle value threshold is calculated based on the set formula. As can be seen from the formula, the duty cycle value threshold is calculated based on the power supply voltage phase and the attenuation coefficient, which can further limit the duty cycle value to obtain the duty cycle value threshold. The duty cycle value threshold and the duty cycle value have the same maximum value, which is 1. This makes the limitation of the duty cycle value threshold on the duty cycle value always within a reasonable range, further ensuring the rationality of the limitation on the duty cycle value. The limitation on the duty cycle value is more ideal, which ensures that the power factor compensation circuit will not damage electronic components due to excessive current when in the starting stage. When the starting stage is completed, the attenuation coefficient is zero, ending the limitation on the duty cycle value, so that the power factor compensation circuit can normally operate in the running stage.

[0107] Please refer to Figure 7 , Figure 7 A flowchart for limiting and modifying the duty cycle value according to the numerical relationship between the duty cycle value threshold and the duty cycle value according to an embodiment of the present application is shown. The embodiment of the present application provides a step S320 for limiting and modifying the duty cycle value according to the numerical relationship between the duty cycle value threshold and the duty cycle value, which includes:

[0108] Step S321, taking the smaller value between the duty cycle value and the duty cycle value threshold as the limited and modified duty cycle value.

[0109] Step S322, if the duty cycle value and the duty cycle value threshold are the same, taking any one of the duty cycle value and the duty cycle value threshold as the limited and modified duty cycle value.

[0110] The above two steps will be described in detail below.

[0111] In step S321, the smaller value between the duty cycle value and the duty cycle value threshold is taken as the limited and modified duty cycle value, that is, the duty cycle value cannot be smaller than the duty cycle value threshold, otherwise it is possible that the duty cycle value threshold is the current power grid that will not appear current over-limit duty cycle value.

[0112] In step S322, if the duty cycle value and the duty cycle value threshold are the same, any one of the duty cycle value and the duty cycle value threshold is taken as the limited and modified duty cycle value.

[0113] In the embodiment of the present application, by comparing the duty cycle value and the duty cycle value threshold, taking the smaller one as the limited and modified duty cycle value, if the duty cycle value and the duty cycle value threshold are the same, any one of the duty cycle value and the duty cycle value threshold is taken as the limited and modified duty cycle value. This can limit the duty cycle value very simply, reduce the calculation burden and improve the calculation efficiency.

[0114] In one embodiment of the present application, the duty cycle value is calculated according to the load voltage of the load circuit, the phase of the input current of the inductive module, and the voltage command indicating the required voltage of the load circuit. The load voltage is obtained, for example, by using a voltage sensor or a voltmeter to measure the load voltage. The voltage error is calculated, which is the difference between the voltage command and the load voltage. The gain of the power factor compensation circuit is determined, which is a proportional factor used to convert the voltage error into the adjustment amount of the duty cycle. The gain is determined according to the specific characteristics of the load circuit 3, such as the phase of the input current, and the requirements of the load circuit 3 or the power grid, such as current limit, overvoltage protection, overcurrent protection, etc.

[0115] In another embodiment of the present application, PID (Proportional-Integral-Derivative) is used to more accurately calculate the duty cycle value. This can automatically adjust the duty cycle value according to the dynamic characteristics and requirements of the system, achieving more stable and accurate control effect.

[0116] In the embodiment of the present application, the smaller one of the duty cycle value and the duty cycle value threshold is taken as the limited modified duty cycle value by comparing the duty cycle value and the duty cycle value threshold. If the duty cycle value and the duty cycle value threshold are the same, either of the duty cycle value and the duty cycle value threshold is taken as the limited modified duty cycle value. This can limit the duty cycle value simply, reduce the calculation burden, and improve the calculation efficiency.

[0117] Please refer to Figure 8 , Figure 8 A flowchart for calculating the duty cycle value according to the load voltage of the load circuit, the phase of the input current of the inductive module, and the voltage command indicating the required voltage of the load circuit is shown according to one embodiment of the present application. The embodiment of the present application provides steps for calculating the duty cycle value according to the load voltage of the load circuit, the phase of the input current of the inductive module, and the voltage command indicating the required voltage of the load circuit, including:

[0118] Step S801, modifying the required amplitude of the input current according to the difference between the voltage command and the load voltage;

[0119] Step S802, modifying the required phase of the input current according to the phase information of the load voltage and the phase information of the input current;

[0120] Step S803, calculating the duty cycle value according to the required amplitude of the input current and the required phase of the input current.

[0121] The above three steps are described in detail as follows.

[0122] In step 8501, the required amplitude of the input current is corrected based on the difference between the voltage command and the load voltage. The difference between the voltage command and the load voltage indicates the error between the current load voltage and the voltage indicated by the voltage command; therefore, the required load voltage value can be determined based on this difference. Since the purpose of the power factor compensation circuit is to make the voltage waveform and current waveform coincide in phase, the required load voltage value can determine the required amplitude of the input current.

[0123] In step S802, the required phase of the input current is determined based on the phase information of the load voltage and the phase information of the input current.

[0124] In step S803, the duty cycle value is calculated based on the required amplitude and phase of the input current. The duty cycle value is used to control the switching device to open and close periodically, so that the amplitude and phase of the input current approach the required phase and amplitude of the input current infinitely.

[0125] The method provided in the embodiments of this application allows for faster and more direct acquisition of duty cycle values.

[0126] In this embodiment, when the power factor compensation circuit starts up, the duty cycle value is calculated based on the current and voltage information in the power grid. However, this duty cycle value is not repeatedly corrected based on the circuit's operating performance. Therefore, it inevitably leads to excessively high current compensation values, which can impact electronic components in the power grid and cause damage. Therefore, this embodiment limits and corrects the calculated duty cycle value to a certain extent, ensuring that the duty cycle value is below a certain threshold when put into use. This avoids situations where the load voltage is too high and the current is too high due to the initial duty cycle value.

[0127] In one embodiment of this application, if the input current is greater than or equal to the recovery threshold and less than the danger threshold for a set duration, the switching device is controlled to switch on and off according to a limited duty cycle value. In this embodiment, if the input current is greater than or equal to the recovery threshold and less than the danger threshold for a set duration, the switching device is controlled to switch on and off according to a limited duty cycle value. This avoids the input current repeatedly fluctuating at the danger threshold, which would cause the switching device's operating mode to change repeatedly, increasing the computational burden.

[0128] In another embodiment of this application, the switching device is controlled to switch on and off according to the latest obtained limit duty cycle value.

[0129] In this embodiment, the newly obtained duty cycle limit value is more in line with the current situation of the power factor compensation circuit. The newly obtained duty cycle limit value can better control the switching devices and avoid the current from being over-limited due to the error of the duty cycle value.

[0130] In one embodiment of the present application, please refer to Figure 9 , Figure 9 The schematic diagram of the power factor compensation circuit according to another embodiment of the present application is shown. When the improper power supply is an alternating current power supply, the power factor compensation circuit further comprises a rectification module 5, which is used to convert the alternating current generated by the alternating current power supply 1 into a periodic direct current. The first end of the switching device 3 is electrically connected to the first output end of the rectification module 5 through the inductance module 2, and the second end of the switching device is electrically connected to the second output end of the rectification module 5.

[0131] This makes the power factor compensation circuit in the embodiment of the present application can be universally applied to different circuits, greatly increasing the scope of application of the present application.

[0132] It should be noted that the storage threshold value shown in the embodiment of the present application can be a computer readable signal medium or a computer readable storage medium or any combination of the above two. The computer readable storage medium may, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or component, or any combination of the above. More specific examples of computer readable storage medium can include, but are not limited to: electrical connection with one or more conductive wires, portable computer disk, hard disk, random access memory (RAM), read only memory (ROM), erasable programmable read only memory (EPROM), flash memory, optical fiber, portable compact disk read only memory (Compact Disc Read-Only Memory, CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the above. In the present application, the computer readable storage medium can be any tangible medium containing or storing programs that can be used or combined with instruction execution system, device or component. In the present application, the computer readable signal medium can include data signals propagating in the baseband or as part of a carrier wave, which carries computer readable program code. Such propagating data signals can take many forms, including but not limited to electromagnetic signals, optical signals or any suitable combination of the above. The computer readable signal medium can also be any storage threshold value other than the computer readable storage medium, which can send, propagate or transmit programs for use by or in combination with instruction execution system, device or component. The program code contained in the storage threshold value can be transmitted by any suitable medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0133] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0134] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0135] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, touch terminal, or network device, etc.) to execute the method according to the embodiments of this application.

[0136] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0137] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A power factor compensation circuit, characterized in that, The circuit includes: A switching device, wherein the first terminal of the switching device is electrically connected to the first terminal of the power supply through an inductor module, and the second terminal of the switching device is electrically connected to the second terminal of the power supply; A load circuit, wherein a first terminal of the load circuit is connected to a first terminal of the switching device, and a second terminal of the load circuit is connected to a second terminal of the switching device; A controller, electrically connected to the control terminal of the switching device, is used to input a pulse width adjustment signal to the control terminal of the switching device; The controller is configured to: Obtain the duty cycle value of the pulse width adjustment signal, and calculate the duty cycle threshold value based on the power supply voltage phase and the preset attenuation coefficient; The duty cycle value is restricted and corrected according to the duty cycle value threshold; The switching device is controlled to periodically switch on and off based on the duty cycle value after the limitation correction.

2. The circuit according to claim 1, characterized in that, Before acquiring the duty cycle value of the pulse width adjustment signal and calculating the duty cycle threshold value based on the power supply voltage phase and a preset attenuation coefficient, the method further includes: If the attenuation coefficient is being used for the first time, it will be used directly to calculate the duty cycle threshold. If the number of times the attenuation coefficient is used is greater than 1, then the attenuation variable of the attenuation coefficient is obtained, and the attenuation coefficient is updated according to the attenuation variable.

3. The circuit according to claim 2, characterized in that, The step of updating the attenuation coefficient based on the attenuation variable includes: Obtain the attenuation variable of the attenuation coefficient; If the attenuation coefficient is less than or equal to the attenuation coefficient variable, then the attenuation coefficient is updated to zero; If the attenuation coefficient is greater than the attenuation coefficient variable, then the difference between the attenuation coefficient and the attenuation coefficient variable is used as the updated attenuation coefficient.

4. The circuit according to claim 3, characterized in that, The attenuation variable for obtaining the attenuation coefficient includes: The quotient between the start-up time of the power factor compensation circuit and the operating cycle of the control method is taken as the number of attenuation times; The ratio of the decay variable to the number of decays is used as the decay variable.

5. The circuit according to claim 1, characterized in that, The step of calculating the duty cycle threshold based on the power supply voltage phase and a preset attenuation coefficient includes: The duty cycle threshold value is calculated using the following formula based on the updated attenuation coefficient and the power supply voltage phase: D m =1-K d *|sinθ s | Wherein, the D m K is the threshold value for the duty cycle. d sinθ is the attenuation coefficient. s This represents the phase of the power supply voltage.

6. The circuit according to claim 1, characterized in that, The step of limiting and correcting the duty cycle value according to the duty cycle value threshold includes: The smaller of the duty cycle value and the duty cycle threshold value is used as the reduced duty cycle value; If the duty cycle value and the duty cycle threshold are the same, then either the duty cycle value or the duty cycle threshold shall be used as the duty cycle value after compression correction.

7. The circuit according to claim 1, characterized in that, The acquisition of the duty cycle value of the pulse width adjustment signal includes: The duty cycle value is calculated based on the load voltage of the load circuit, the phase of the input current of the inductor module, and the voltage command indicating the required voltage of the load circuit.

8. The circuit according to claim 7, characterized in that, The step of calculating the duty cycle value based on the voltage command indicating the required voltage for the load circuit, the load voltage of the load circuit, and the phase of the input current of the inductor module includes: The required amplitude of the input current is adjusted based on the difference between the voltage command and the load voltage. Based on the phase information of the load voltage and the phase information of the input current, the required phase of the input current is corrected; The duty cycle value is calculated based on the required amplitude and phase of the input current.

9. The circuit according to claim 1, characterized in that, The power supply is an AC power supply, and the power factor compensation circuit further includes: A rectifier module is connected to an AC power source to convert AC power supplied by the AC power source into DC power. The first terminal of the switching device is electrically connected to the first output terminal of the rectifier module through an inductor module, and the second terminal of the switching device is electrically connected to the second output terminal of the rectifier module.

10. A household appliance, characterized in that, The system includes a variable frequency motor; and a power factor compensation circuit as described in any one of claims 1-8, wherein the variable frequency motor is located within the load circuit, and the power factor compensation circuit is used to control the variable frequency motor.

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