Power factor compensation circuit and household appliance

Abstract

The embodiment of the invention provides a power factor compensation circuit and a household appliance. The power factor compensation circuit comprises a rectification module; the first end of the switching device is electrically connected with the first output end of the rectification module through the inductance module, and the second end of the switching device is electrically connected with the second output end of the rectification module through the resistance module; the first end of the load circuit is connected to the first end of the switching device, and the second end of the load circuit is connected to the second end of the switching device; the controller is electrically connected with the control end of the switching device and is configured to input a control signal to the switching device to control the switching device to be switched on; acquiring a plurality of current values sampled for the resistor module in a conduction period of the switching device; determining the current change rate of the inductance module according to the variable quantity of the plurality of current values and the sampling interval duration; and determining the voltage value of the alternating current according to the current change rate of the inductance module and the inductance value of the inductance module. According to the embodiment of the invention, the cost of a hardware circuit can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power factor compensation, in particular 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, the common treatment method is to use power factor compensation.

[0003] Power factor compensation, that is, by installing a parallel capacitor reactive power compensation device in the power grid, the reactive power consumed by the inductive load can be compensated, thereby reducing the reactive power provided by the power grid power supply and in the transmission line process.

[0004] However, power factor compensation usually needs to collect the voltage value of the alternating current input, and the common way at present is to connect a sampling resistor in parallel in the circuit to sample the alternating current provided by the alternating current power supply through the parallel sampling resistor.

[0005] However, the parallel sampling resistor method will increase the new sampling resistor, which inevitably leads to an increase in the cost of the hardware circuit. SUMMARY

[0006] To solve the above technical problems, the embodiments of the present application provide a power factor compensation circuit and a household appliance.

[0007] According to some aspects of the embodiments of the present application, the embodiments of the present application provide a power factor compensation circuit, which comprises: a rectification module connected to an alternating current power supply, for converting alternating current provided by the alternating current power supply into direct current; a switching device, a first end of the switching device being electrically connected to a first output end of the rectification module through an inductor module, and a second end of the switching device being electrically connected to a second output end of the rectification module through a resistor module; a load circuit, a first end of the load circuit being connected to the first end of the switching device, and a second end of the load circuit being connected to the second end of the switching device; and a controller, the controller being electrically connected to a control end of the switching device, and the controller being configured to perform the following steps: inputting a control signal to the switching device to control the switching device to be turned on; during one conduction period of the switching device, obtaining a plurality of current values sampled for the resistor module; determining a current change rate of the inductor module according to a change amount of the plurality of current values and a sampling interval length; and determining a voltage value of the alternating current according to the current change rate of the inductor module and an inductance of the inductor module.

[0008] In the above embodiment, during one conduction period of the switching device, a plurality of current values sampled by the resistance module are obtained, and the current change rate of the inductance module is quickly determined according to the change amount between the plurality of current values and the sampling interval length, and then the voltage value of the alternating current is accurately calculated according to the inductance change rate of the inductance module and the inductance of the inductance module; thus, the voltage value of the alternating current is calculated without adding a new sampling resistor, thereby reducing the cost of the power factor compensation circuit.

[0009] In some embodiments of the present application, based on the foregoing scheme, the control signal is input to the switching device to control the switching device to conduct, comprising: inputting a periodic signal to the switching device to control the switching device to conduct periodically.

[0010] In some embodiments of the present application, based on the foregoing scheme, the current change rate of the inductance module is determined according to the change amount of the plurality of current values and the sampling interval length, comprising: selecting two current values from the plurality of current values and determining the sampling interval length between the two current values; determining the current change rate of the inductance module according to the change amount of the two current values and the sampling interval length between the two current values.

[0011] In the above embodiment, two current values can be selected from the plurality of current values, and the sampling interval length between the two current values is determined, so that the current change rate of the inductance module can be quickly and accurately determined according to the change amount of the two current values and the sampling interval length between the two current values.

[0012] In some embodiments of the present application, based on the foregoing scheme, the plurality of current values sampled by the resistance module are obtained during one conduction period of the switching device, comprising: determining a first current sampling time point and a second current sampling time point during one conduction period of the switching device; obtaining a first current value sampled by the resistance module at the first current sampling time point, and obtaining a second current value sampled by the resistance module at the second current sampling time point.

[0013] In the above embodiment, the first current sampling time point and the second current sampling time point can be determined during one conduction period of the switching device, so that the first current value sampled by the resistance module at the first current sampling time point and the second current value sampled by the resistance module at the second current sampling time point can be obtained.

[0014] In some embodiments of the present application, based on the foregoing scheme, the first current sampling time point is the nearest time point when the switching device is off and adjacent to conduction, and the second current sampling time point is the time point when the switching device is on.

[0015] In the above embodiment, the first current sampling time point can be the latest time point at which the switch device is off and adjacent to on, and the second current sampling time point can be the time point at which the switch device is on, so as to prevent the inaccuracy of the sampled current when the switch device is on, and further affect the current change rate of the inductance module.

[0016] In some embodiments of the present application, based on the foregoing scheme, the first current sampling time point is the time point at which the switch device is on, and the second current sampling time point is the latest time point at which the switch device is on and adjacent to off.

[0017] In the above embodiment, the first current sampling time point can be the latest time point at which the switch device is off and adjacent to on, and the second current sampling time point can be the time point at which the switch device is on, so as to prevent the inaccuracy of the sampled current when the switch device is on, and further affect the current change rate of the inductance module.

[0018] In some embodiments of the present application, based on the foregoing scheme, the first current sampling time point is the latest time point at which the switch device is off and adjacent to on, and the second current sampling time point is the latest time point at which the switch device is on and adjacent to off.

[0019] In the above embodiment, the first current sampling time point can be the latest time point at which the switch device is off and adjacent to on, and the second current sampling time point can be the time point at which the switch device is on, so as to prevent the inaccuracy of the sampled current when the switch device is on, and further affect the current change rate of the inductance module.

[0020] In some embodiments of the present application, based on the foregoing scheme, the sampling interval is the difference between the second current sampling time point and the first current sampling time point.

[0021] In some embodiments of the present application, based on the foregoing scheme, the determination of the voltage value of the alternating current according to the current change rate of the inductance module and the inductance of the inductance module comprises: calculating the product between the current change rate of the inductance module and the inductance of the inductance module; and determining the voltage value of the alternating current according to the product.

[0022] In the above embodiment, the voltage value of the alternating current can be accurately determined according to the product between the current change rate of the inductance module and the inductance of the inductance module.

[0023] In some embodiments of the present application, the present application provides a household appliance, comprising: a variable frequency motor; and a power factor compensation circuit as described above, the variable frequency motor being contained in the load circuit, and the power factor compensation circuit being used for controlling the variable frequency motor.

[0024] It should be understood that the general description above and the detailed description below are only exemplary and explanatory, and are not restrictive of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and serve to explain the principles of the present application. It is readily apparent to one of ordinary skill in the art that the accompanying drawings only illustrate some embodiments of the present application, and other drawings can be obtained by one of ordinary skill in the art without any creative effort, based on the accompanying drawings. In the drawings:

[0026] Figure 1 is a structural schematic diagram of a power factor compensation circuit provided by an exemplary embodiment of the present application;

[0027] Figure 2 is a structural schematic diagram of a power factor compensation circuit provided by an exemplary embodiment of the present application;

[0028] Figure 3 is a structural schematic diagram of a power factor compensation circuit provided by another exemplary embodiment of the present application;

[0029] Figure 4 is a structural schematic diagram of a power factor compensation circuit provided by another exemplary embodiment of the present application;

[0030] Figure 5 is a structural schematic diagram of a power factor compensation circuit provided by another exemplary embodiment of the present application;

[0031] Figure 6 is a schematic diagram of current sampling time point distribution provided by an exemplary embodiment of the present application;

[0032] Figure 7 is a schematic diagram of current sampling time point distribution provided by another exemplary embodiment of the present application;

[0033] Figure 8 is a schematic diagram of current sampling time point distribution provided by another exemplary embodiment of the present application;

[0034] Figure 9 is a schematic diagram of current sampling time point distribution provided by another exemplary embodiment of the present application.

[0035] EXPLANATION OF REFERENCE NUMERALS:

[0036] 1: rectification module;

[0037] 2: inductance module;

[0038] 3: switching device;

[0039] 4: resistance module;

[0040] 5: load circuit;

[0041] 51: diode;

[0042] 52: capacitance module;

[0043] 6: sampling resistance;

[0044] 100: power factor compensation circuit. DETAILED DESCRIPTION

[0045] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, like reference numerals refer to like elements, unless the context clearly dictates otherwise. The following description is not meant to limit all embodiments consistent with the present application to the embodiments described. Rather, the following description is meant to provide examples of apparatus and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0046] The flow charts shown in the drawings are only exemplary illustrations, and do not necessarily include all contents and operations / steps, nor do they have to be executed in the order described. For example, some operations / steps can be further broken down, while some operations / steps can be combined or partially combined, so the actual execution order can be changed according to actual conditions. It should also be noted that "multiple" as mentioned in the present application means two or more. The association relationship of "and / or" describes the association of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0047] The terms "first", "second", "third", and "fourth" and the like in the specification and claims of the present application and the drawings are used to distinguish different objects, and are not intended to describe a particular order. The terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0048] Power factor compensation generally requires collecting the voltage value of the AC input. The commonly used method is to connect a sampling resistance in parallel in the circuit, and through the parallel sampling resistance to sample the AC power provided by the AC power supply.

[0049] Please refer to Figure 1 , Figure 1 is a structural schematic diagram of the power factor compensation circuit provided by the exemplary embodiments. As Figure 1As shown, the power factor compensation circuit includes a sampling resistor 6. Currently, in order to acquire the voltage value of the AC power supplied by the AC power source, it is necessary to set up a resistor such as... Figure 1 The sampling resistor 6 is shown.

[0050] like Figure 1 As shown, sampling resistor 6 can be configured to have 2 units.

[0051] Furthermore, the sampling resistor 6 is connected in parallel with the switching device in the power factor compensation circuit. By setting the sampling resistor 6 in parallel, the DC current is divided.

[0052] After DC voltage division, the voltage signal can be converted into a digital signal by the analog-to-digital converter (ADC) in the microcontroller, thereby enabling the acquisition of AC power supplied by the AC power source.

[0053] Ultimately, the operation of the power factor compensation circuit is adjusted based on the collected AC power, thereby enabling the power factor compensation circuit to cancel out the reactive power in the electrical equipment.

[0054] However, using parallel sampling resistors will inevitably increase the cost of hardware circuitry by adding new sampling resistors.

[0055] To solve the above-mentioned technical problems, this application designs a power factor compensation circuit 100.

[0056] Please see Figure 2 , Figure 2 This is a schematic diagram of the power factor compensation circuit provided in an exemplary embodiment of this application.

[0057] like Figure 2 As shown, the power factor compensation circuit 100 may include a rectifier module 1.

[0058] Rectifier module 1 is connected to an AC power source. Rectifier module 1 can be used to convert AC power supplied by the AC power source into DC power.

[0059] In some embodiments of this application, the alternating current is a 50 Hz sine wave. After passing through the rectifier module 1, the current is allowed to flow in only one direction, thereby eliminating the negative half-cycle in the alternating current. In this way, the originally time-varying sinusoidal alternating current is converted into a unidirectional current, i.e., direct current.

[0060] The first output terminal of rectifier module 1 can be electrically connected to inductor module 2. The second output terminal of rectifier module 1 can be electrically connected to resistor module 4.

[0061] In some embodiments of this application, the rectifier module 1 may be a half-wave rectifier circuit.

[0062] The half-wave rectification circuit can include a rectifier diode D1. The positive electrode of the rectifier diode D1 is connected to one end of the AC power supply to achieve the purpose of limiting the current output by the AC power supply to flow in only one direction, thereby converting the AC power with a time-varying current direction into DC power with a unidirectional current flow.

[0063] In some embodiments of the present application, the rectification module 1 can include a full-wave rectification circuit.

[0064] The full-wave rectification circuit can include a rectifier diode D2 and a rectifier diode D3. The positive electrodes of the rectifier diode D2 and the rectifier diode D3 are respectively connected to the two current output ends of the AC power supply, and the positive electrode of the rectifier diode D2 and the negative electrode of the rectifier diode D3 are connected to each other to achieve the purpose of limiting the current output by the AC power supply to flow in only one direction, thereby converting the AC power with a time-varying current direction into DC power with a unidirectional current flow.

[0065] In some embodiments of the present application, the rectification module 1 can include a bridge rectification circuit.

[0066] Please refer to Figure 3 , Figure 3 is a structural diagram of a power factor compensation circuit provided by another exemplary embodiment of the present application. As Figure 3 shown, the bridge rectification circuit can include a rectifier diode D4, a rectifier diode D5, a rectifier diode D6, and a rectifier diode D7.

[0067] The positive electrode of the rectifier diode D4 and the positive electrode of the rectifier diode D6 are connected, the negative electrode of the rectifier diode D4 and the positive electrode of the rectifier diode D5 are connected, the negative electrode of the rectifier diode D5 and the negative electrode of the rectifier diode D7 are connected, and the negative electrode of the rectifier diode D6 and the positive electrode of the rectifier diode D7 are connected.

[0068] One current output end of the AC power supply is connected between the negative electrode of the rectifier diode D4 and the positive electrode of the rectifier diode D5, and the other current output end of the AC power supply is connected between the negative electrode of the rectifier diode D6 and the positive electrode of the rectifier diode D7 to achieve the purpose of limiting the current output by the AC power supply to flow in only one direction, thereby converting the AC power with a time-varying current direction into DC power with a unidirectional current flow.

[0069] In some embodiments of the present application, the power factor compensation circuit 100 can include an inductance module 2.

[0070] The inductance module 2 can be electrically connected to the first output end of the rectification module 1. The inductance module 2 can be electrically connected to the first end of the switching device 3. The inductance module 2 can be electrically connected to the first end of the load circuit.

[0071] The inductance module 2 can help filter out harmonics and noise in the power factor compensation circuit 100, improve the stability and reliability of the power factor compensation circuit 100.

[0072] The inductance module 2 can smooth the voltage fluctuation in the power factor compensation circuit 100 to output a stable voltage signal.

[0073] In some embodiments of the present application, the power factor compensation circuit 100 can include a switching device 3.

[0074] The switching device 3 can be used to conduct under the control of a control signal.

[0075] In some embodiments of the present application, the first end of the switching device 3 can be electrically connected to the first output end of the rectification module 1, and the second end of the switching device 3 can be electrically connected to the second output end of the rectification module 1, so that the switching device 3 forms a path with the rectification module 1 when the switching device 3 is turned on under the control of the control signal.

[0076] In some embodiments of the present application, the first end of the switching device 3 can be electrically connected to the first output end of the rectification module 1 through the inductance module 2, and the second end of the switching device 3 can be electrically connected to the second output end of the rectification module 1 through the resistance module 4, so that after the switching device 3 forms a path with the rectification module 1 when the switching device 3 is turned on under the control of the control signal, the inductance module 2 can avoid damage caused by short circuit of the alternating current power supply as a load of the path, and the inductance module 2 can reduce harmonic interference generated by the alternating current power supply.

[0077] The first end of the switching device 3 can be connected to the first end of the load circuit 5.

[0078] The second end of the switching device 3 can be connected to the second end of the load circuit 5.

[0079] In some embodiments of the present application, the switching device 3 can have a control end.

[0080] In some embodiments of the present application, the switching device 3 can include an Insulate-Gate Bipolar Transistor (IGBT).

[0081] Please refer to Figure 4 , Figure 4 is a structural schematic diagram of a power factor compensation circuit provided by another exemplary embodiment of the present application. As Figure 4 shown, correspondingly, the collector of the Insulate-Gate Bipolar Transistor serves as the first end of the switching device 3, and the emitter of the Insulate-Gate Bipolar Transistor serves as the second end of the switching device 3.

[0082] In some embodiments of the present application, the switching device 3 can comprise a field effect transistor. Correspondingly, the source of the field effect transistor is the first end of the switching device 3, and the drain of the field effect transistor is the second end of the switching device 3.

[0083] In some embodiments of the present application, the switching device 3 can comprise a triode. Correspondingly, the collector of the triode is the first end of the switching device 3, and the emitter of the triode is the second end of the switching device 3.

[0084] In some embodiments of the present application, the power factor compensation circuit 100 can comprise a resistance module 4.

[0085] The resistance module 4 can be electrically connected to the second output end of the rectification module 1. The resistance module 4 can be electrically connected to the second end of the switching device 3. The resistance module 4 can be electrically connected to the second end of the load circuit 5.

[0086] In some embodiments of the present application, the power factor compensation circuit 100 can comprise a load circuit 5.

[0087] The first end of the load circuit 5 can be connected to the first end of the switching device 3, and the second end of the load circuit 5 can be grounded, so that the switching device 3 forms a path with the rectification module 1 when it is turned off under the control of the control signal, i.e. the load circuit 5 operates by being powered through the rectification module 1.

[0088] In some embodiments of the present application, the first end of the load circuit 5 can be connected to the first end of the switching device 3, and the second end of the load circuit 5 can be connected to the second end of the switching device 3, so as to reduce the number of grounding positions in the circuit and save production costs.

[0089] Please refer to Figure 5 , Figure 5 is a structural schematic diagram of a power factor compensation circuit provided by another exemplary embodiment of the present application. As Figure 5 shown, the load circuit 5 can comprise a diode 51.

[0090] The anode of the diode 51 is connected to the first end of the switching device 3, and the cathode of the diode 51 is connected to the anode of a capacitor module 52, so as to avoid the current released by the capacitor module 52 from leaking to the ground through the switching device 3, and to ensure that resources are not easily wasted.

[0091] In some embodiments of the present application, the load circuit 5 can comprise a capacitor module 52.

[0092] The positive pole of the capacitor module 52 is the first end of the load circuit 5, and the negative pole of the capacitor module 52 is the second end of the load circuit 5, so that when the switching device 3 is turned off under the control of the control signal, the load circuit 5 can operate by power supplied by the rectifier module 1, and the capacitor module 52 can also be charged by the rectifier module 1, so that when the switching device 3 is turned on under the control of the control signal, the load circuit 5 can operate by power supplied by the capacitor module 52.

[0093] In some embodiments of the present application, the power factor compensation circuit 100 can include a controller.

[0094] The controller can be electrically connected to the control end of the switching device 3, and the controller can be configured to perform the following S110-S140.

[0095] S110, inputting a control signal to the switching device to control the switching device to turn on.

[0096] S120, obtaining a plurality of current values sampled for the resistance module during one on period of the switching device.

[0097] S130, determining the current change rate of the inductor module according to the change amount of the plurality of current values and the sampling interval length.

[0098] S140, determining the voltage value of the alternating current according to the current change rate of the inductor module and the inductance of the inductor module.

[0099] The following will be described in detail.

[0100] In S110, the controller can be electrically connected to the control end of the switching device since the switching device can have a control end. Therefore, in some embodiments of the present application, a control signal can be input to the switching device, and the switching device can be controlled to turn on by the control signal.

[0101] In some embodiments of the present application, the control signal input to the switching device can be a periodic signal, and the switching device can be controlled to periodically turn on by the periodic signal.

[0102] In some embodiments of the present application, the periodic signal can be a pulse width modulation signal (PWM).

[0103] The periodic signal refers to a signal that will repeat the same waveform and characteristics after a certain time T. The time T can be referred to as the period of the periodic signal.

[0104] The switching device periodically turns on, that is, the switching device will periodically turn on every certain time T. Similarly, the switching device periodically turns off, that is, the switching device will periodically turn off every certain time T.

[0105] The on duration of the switching device can be determined by the waveform and characteristics of the periodic signal. The off duration of the switching device can also be determined by the waveform and characteristics of the periodic signal.

[0106] For example, the period of the periodic signal is 5s. If the switching device is currently on, the switching device will also be on after 5s. Similarly, if the switching device is currently off, the switching device will also be off after 5s.

[0107] In S120, one on duration of the switching device can be any on duration of the switching device in the longest on duration.

[0108] For example, the period of the switching device is 5s. If the switching device is on in 0s-5s, the switching device will be off in 5s-10s, and then the switching device will continue to be on in 10s-15s, and then the switching device will be off in 15s-20s, and so on.

[0109] As can be seen from the above example, the longest on duration of the switching device is 5s. The longest on duration of the switching device can be 0s-5s, the longest on duration of the switching device can be 10s-15s, and so on.

[0110] Therefore, one on duration of the switching device can be the longest on duration 0s-5s. One on duration of the switching device can be 0s-2s. One on duration of the switching device can be 0s-3s. One on duration of the switching device can be 2s-5s. One on duration of the switching device can be 3s-5s.

[0111] In one on duration of the switching device, a plurality of current values sampled by the resistance module are obtained.

[0112] In some embodiments of the present application, the current values sampled by the resistance module can be periodic sampling. For example, the sampling period is 1s, and one on duration of the switching device is 0s-5s. The resistance module can sample the current value at 0s, the resistance module can sample the current value at 1s, and so on, and the resistance module can sample the current value at 5s.

[0113] In some embodiments of the present application, the current values sampled by the resistance module can be non-periodic sampling. For example, one on duration of the switching device is 0s-5s. The resistance module can sample the current value at 2s, the resistance module can sample the current value at 2.6s, and the resistance module can sample the current value at 3.3s.

[0114] The resistance module can be used to sample the current value of the current flowing through itself.

[0115] Since the resistance module is connected in series with the inductance module, the current value sampled by the resistance module is equal to the current value of the inductance module.

[0116] It should be noted that when the switching device is turned on, the current of the inductance module will rise. When the switching device is turned off, the current of the inductance module will decrease.

[0117] Therefore, even if the switching device is in the same conduction period, the current value sampled by the resistance module will be different at different sampling times.

[0118] It can be understood that in one conduction period of the switching device, the longer the on time of the switching device, the greater the current value sampled by the resistance module.

[0119] In one conduction period of the switching device, the shorter the on time of the switching device, the smaller the current value sampled by the resistance module.

[0120] In some embodiments of the present application, in one conduction period of the switching device, the step S120 of obtaining a plurality of current values sampled by the resistance module can include:

[0121] S210, determining a first current sampling time point and a second current sampling time point in one conduction period of the switching device.

[0122] S220, obtaining a first current value sampled by the resistance module at the first current sampling time point and a second current value sampled by the resistance module at the second current sampling time point.

[0123] Further, if one conduction period of the switching device 3 is 0s-5s, the first current sampling time point is the 1st second, and the second current sampling time point is the 3rd second, the first current value sampled by the resistance module is obtained at the 1st second, and the second current value sampled by the resistance module is obtained at the 3rd second.

[0124] Similarly, if one conduction period of the switching device is 1s-5s, the first current sampling time point is the 2nd second, and the second current sampling time point is the 3rd second, the first current value sampled by the resistance module is obtained at the 2nd second, and the second current value sampled by the resistance module is obtained at the 3rd second.

[0125] As can be seen from S210-S220 above, the first current sampling time point and the second current sampling time point can be determined in one conduction period of the switching device, so that the first current value sampled by the resistance module at the first current sampling time point and the second current value sampled by the resistance module at the second current sampling time point can be obtained.

[0126] In some embodiments of the present application, the sampling interval can be the difference between the second current sampling time point and the first current sampling time point.

[0127] Referring to Figure 6 , Figure 6 is a schematic diagram of distribution of current sampling time points provided by an exemplary embodiment of the present application. As shown in Figure 6 , the horizontal axis can represent time. The vertical axis can represent a voltage waveform. The vertical axis can represent a current waveform. The vertical axis can also represent a periodic signal.

[0128] As can be seen from Figure 6 , the period between the current sampling time point T1 and the current sampling time point T2 is one conduction period of the switching device.

[0129] During one conduction period of the switching device, the current waveform rises as the conduction time of the switching device increases.

[0130] The first current sampling time point can be the moment when the switching device is turned on. The second sampling time point can be the moment when the switching device is turned on.

[0131] In some embodiments of the present application, one conduction period of the switching device is 1s-5s, the first current sampling time point can be the 2s, and the second current sampling time point can be the 3s.

[0132] In some embodiments of the present application, one conduction period of the switching device is 1s-5s, the first current sampling time point can be the 2.2s, and the second current sampling time point can be the 2.5s.

[0133] Considering that sampling starts when the switching device is turned on, the switching device will have a great interference on sampling at the moment of conduction, resulting in inaccurate current values of sampling.

[0134] Therefore, in some embodiments of the present application, sampling is performed at the nearest moment when the switching device is turned off and is adjacent to conduction, rather than at the moment when the switching device is just turned on.

[0135] Referring to Figure 7 , Figure 7 is a schematic diagram of distribution of current sampling time points provided by another exemplary embodiment of the present application. As shown in Figure 7 , the first current sampling time point can be the nearest moment when the switching device is turned off and is adjacent to conduction. The second current sampling time point can be the moment when the switching device is turned on.

[0136] In some embodiments of the present application, one conduction period of the switching device is 1s-5s, the first current sampling time point can be the 0.9s, and the second current sampling time point can be the 3s.

[0137] In some embodiments of the present application, the on period of the switching device is 1s-5s, the first current sampling time point can be the 0.95s, and the second current sampling time point can be the 4s.

[0138] As can be seen from the above, the first current sampling time point can be the time when the switching device is on, and the second current sampling time point can be the nearest time when the switching device is on and adjacent to off, so as to prevent the inaccuracy of the sampled current when the switching device is on, and thus affect the subsequent calculation of the current change rate of the inductor module.

[0139] Referring to Figure 8 , Figure 8 is a current sampling time point distribution diagram provided by another exemplary embodiment of the present application. As shown in Figure 8 , the first current sampling time point is the time when the switching device is on. The second current sampling time point is the nearest time when the switching device is on and adjacent to off.

[0140] In some embodiments of the present application, the on period of the switching device is 1s-5s, the first current sampling time point can be the 2s, and the second current sampling time point can be the 4.9s.

[0141] In some embodiments of the present application, the on period of the switching device is 1s-5s, the first current sampling time point can be the 2.2s, and the second current sampling time point can be the 4.95s.

[0142] As can be seen from the above, the first current sampling time point can be the time when the switching device is on, and the second current sampling time point can be the nearest time when the switching device is on and adjacent to off, so as to prevent the inaccuracy of the sampled current when the switching device is on, and thus affect the subsequent calculation of the current change rate of the inductor module.

[0143] Referring to Figure 9 , Figure 9 is a current sampling time point distribution diagram provided by another exemplary embodiment of the present application. As shown in Figure 9 , the first current sampling time point is the nearest time when the switching device is off and adjacent to on. The second current sampling time point is the nearest time when the switching device is on and adjacent to off.

[0144] In some embodiments of the present application, the on period of the switching device is 1s-5s, the first current sampling time point can be the 0.9s, and the second current sampling time point can be the 4.9s.

[0145] In some embodiments of the present application, the on period of the switching device is 1s-5s, the first current sampling time point can be the 0.95s, and the second current sampling time point can be the 4.95s.

[0146] As can be seen from the above, the first current sampling time point can be the nearest time point at which the switch device is off and adjacent to on, and the second current sampling time point can be the nearest time point at which the switch device is on and adjacent to off, thereby preventing the sampled current from being inaccurate when the switch device is on or off, and thereby affecting the subsequent calculation of the current change rate of the inductance module.

[0147] In S130, the change amount of the plurality of current values includes a change amount between two current values in the plurality of current values. The sampling interval duration of the plurality of current values includes an interval duration between current sampling time points corresponding to two current values in the plurality of current values.

[0148] In some embodiments of the present application, according to the change amount of the plurality of current values and the sampling interval duration, the step S130 of determining the current change rate of the inductance module can include:

[0149] S310, selecting two current values from the plurality of current values, and determining a sampling interval duration between the two current values.

[0150] S320, according to the change amount of the two current values and the sampling interval duration between the two current values, determining the current change rate of the inductance module.

[0151] Further, the selection of the two current values from the plurality of current values can be randomly selected. The selection of the two current values from the plurality of current values can be selected according to a preset rule.

[0152] According to the selected two current values, the sampling time points corresponding to the two current values can be determined, and thus the sampling interval duration between the two current values can be determined.

[0153] The sampling interval duration between the two current values is equal to the time difference between the sampling time points of the two current values.

[0154] According to the change amount of the two current values and the sampling interval duration between the two current values, the current change rate of the inductance module can be quickly and accurately determined.

[0155] As can be seen from the above S310-S320, the present embodiment can select two current values from the plurality of current values, and determine the sampling interval duration between the two current values, so that the current change rate of the inductance module can be quickly and accurately determined according to the change amount of the two current values and the sampling interval duration between the two current values.

[0156] In S140, the inductance of the inductance module can be determined according to the rated power of the load circuit. The inductance of the inductance module can be determined according to the actual power of the load circuit.

[0157] In some embodiments of the present application, the voltage value of the alternating current can be determined according to the current change rate of the inductive module, the inductance of the inductive module, and the error parameter.

[0158] As can be seen from S110-S140, in one conduction period of the switching device, a plurality of current values sampled by the resistance module are obtained, and the current change rate of the inductive module is quickly determined according to the change amount between the plurality of current values and the sampling interval time length, and then the voltage value of the alternating current is accurately calculated according to the inductance change rate of the inductive module and the inductance of the inductive module. Thus, the voltage value of the alternating current is calculated without adding a new sampling resistor, thereby reducing the cost of the power factor compensation circuit.

[0159] In some embodiments of the present application, the step S140 of determining the voltage value of the alternating current according to the current change rate of the inductive module and the inductance of the inductive module can include:

[0160] S410, calculating the product between the current change rate of the inductive module and the inductance of the inductive module.

[0161] S420, determining the voltage value of the alternating current according to the product.

[0162] Further, the voltage value of the direct current is equal to the product between the current change rate of the inductive module and the inductance of the inductive module. The formula can be indirectly expressed as follows:

[0163]

[0164] Where di÷dt represents the current change rate of the inductive module, U represents the voltage value of the direct current, and L represents the inductance of the inductive module.

[0165] In some embodiments of the present application, the formula can also be expressed as follows:

[0166]

[0167] Where I2-I1 represents the difference between the second current value and the first current value, ΔT represents the difference between the second current sampling time point and the first current sampling time point, U represents the voltage value of the direct current, and L represents the inductance of the inductive module.

[0168] As can be seen from S410-S420, the voltage value of the alternating current can be accurately determined according to the product between the current change rate of the inductive module and the inductance of the inductive module.

[0169] It should be noted that the voltage value of the direct current is equal to the voltage value of the alternating current.

[0170] Therefore, after the voltage value of the direct current is determined, the voltage value of the direct current can be taken as the voltage value of the alternating current, so that the voltage value of the alternating current is determined.

[0171] In some embodiments of the present application, the present application also provides a household appliance, comprising: a variable frequency motor; and the power factor compensation circuit as above, the variable frequency motor being contained in a load circuit, and the power factor compensation circuit being used for controlling the variable frequency motor.

[0172] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the present application cover any and all variations of the present application comprising modifications and / or additions of fit, including such departures from the present disclosure as come within known or customary practice in the art to which the present application pertains.

[0173] It should be understood that the above description is only the preferred exemplary embodiment of the present application, and is not intended to limit the embodiments of the present application. Those skilled in the art can easily make corresponding changes or modifications according to the main concept and spirit of the present application, and the protection scope of the present application should be subject to the protection scope required by the claims.

Claims

1. A power factor compensation circuit, characterized by, The circuit comprises: a rectifier module connected to an alternating current power supply and configured to convert alternating current provided by the alternating current power supply into direct current; a switching device, a first end of the switching device being electrically connected to a first output end of the rectifier module through an inductor module, and a second end of the switching device being electrically connected to a second output end of the rectifier module through a resistor module; a load circuit, a first end of the load circuit being connected to the first end of the switching device, and 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, and the controller being configured to perform the following steps: inputting a control signal to the switching device to control the switching device to be turned on; acquiring a plurality of current values sampled for the resistor module within one on-period of the switching device; determining a current change rate of the inductor module according to a variation of the plurality of current values and a sampling interval length; determining a voltage value of the alternating current according to the current change rate of the inductor module and an inductance of the inductor module.

2. The power factor compensation circuit of claim 1, wherein, The step of inputting the control signal to the switching device to control the switching device to be turned on comprises: inputting a periodic signal to the switching device to control the switching device to be periodically turned on.

3. The power factor compensation circuit of claim 1, wherein, The step of determining the current change rate of the inductor module according to the variation of the plurality of current values and the sampling interval length comprises: selecting two current values from the plurality of current values and determining a sampling interval length between the two current values; determining the current change rate of the inductor module according to a variation of the two current values and the sampling interval length between the two current values.

4. The power factor compensation circuit of claim 1, wherein, The step of acquiring the plurality of current values sampled for the resistor module within one on-period of the switching device comprises: determining a first current sampling time point and a second current sampling time point within one on-period of the switching device; acquiring a first current value sampled for the resistor module at the first current sampling time point and a second current value sampled for the resistor module at the second current sampling time point.

5. The power factor compensation circuit of claim 4, wherein, The first current sampling time point is a nearest time point at which the switching device is turned off and adjacent to being turned on, and the second current sampling time point is a time point at which the switching device is turned on.

6. The power factor compensation circuit of claim 4, wherein, The first current sampling time point is a time point at which the switching device is turned on, and the second current sampling time point is a nearest time point at which the switching device is turned on and adjacent to being turned off.

7. The power factor compensation circuit of claim 4, wherein, The first current sampling time point is a nearest time point at which the switching device is turned off and adjacent to being turned on, and the second current sampling time point is a nearest time point at which the switching device is turned on and adjacent to being turned off.

8. The power factor compensation circuit of claim 4, wherein, The sampling interval length is a difference between the second current sampling time point and the first current sampling time point.

9. The power factor compensation circuit of claim 1, wherein, The step of determining the voltage value of the alternating current according to the current change rate of the inductor module and the inductance of the inductor module comprises: calculating a product between the current change rate of the inductor module and the inductance of the inductor module; and determining the voltage value of the alternating current according to the product.

10. A domestic appliance characterized in that, The circuit comprises: a variable frequency motor; and ​ The power factor compensation circuit according to any one of claims 1-9, said variable frequency motor being included in said load circuit, said power factor compensation circuit being used for controlling said variable frequency motor.

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