Power factor compensation circuit, control method and household appliance

Abstract

The invention discloses a power factor compensation circuit, a control method and a household appliance. The circuit comprises a switching device; a load circuit; a controller; the controller is configured as follows: if the input current of the inductance module reaches a first threshold value, the switching device is controlled to keep an off state; according to the duty ratio value of the pulse width adjusting signal before the input current reaches the first threshold value, calculating a duty ratio value threshold value; according to the duty ratio value threshold value, limiting and shrinking adjustment is carried out on the duty ratio value obtained when the switching device is kept in the off state, and a limited duty ratio value is obtained; if the input current is larger than or equal to a second threshold value and smaller than a first threshold value, the switching device is controlled to be switched on and off according to the limiting duty ratio value, and the second threshold value is smaller than the first threshold value. According to the technical scheme, when the current overload problem is solved, the power factor compensation circuit does not 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, a control method 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. installing a parallel capacitor module reactive power compensation device in the power grid 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 some objective factors in the power grid cause current overload in the power grid, the power factor compensation circuit will be automatically closed to prevent some electrical components in the power grid from being broken by current overload. However, when the objective factors disappear, restarting the power factor compensation circuit will also cause the current to exceed the upper limit, although the time is short, but it will also bring a certain risk to the power grid.

[0004] Therefore, in the process of dealing with current overload, how to make the power factor compensation circuit not cause current overload is a technical problem that needs to be solved at present. SUMMARY

[0005] The purpose of the present application is to deal with the problem of current overload, so that the power factor compensation circuit does not cause current overload.

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

[0007] According to an aspect of the embodiments of the present application, a power factor compensation circuit is provided, the circuit comprising: a switching device, a first end of the switching device being electrically connected to a first end of a power supply through an inductor 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, configured to input a pulse width adjustment signal to the control end of the switching device; the controller being configured to: if an input current of the inductor module reaches a first threshold value, control the switching device to remain in an off state; calculate a duty cycle threshold value according to a duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold value; limit and adjust a duty cycle value obtained during the switching device remaining in the off state according to the duty cycle threshold value, to obtain a limited duty cycle value; if the input current is greater than or equal to a second threshold value and less than the first threshold value, control the switching device to be turned on and off according to the limited duty cycle value, the second threshold value being less than the first threshold value.

[0008] In the embodiments of the present application, since the power factor compensation circuit restarts, there is a process of recalculating the duty cycle value, and in this process, the switching device is inevitably controlled to periodically turn on and off with a relatively large error duty cycle value to correct the duty cycle value according to the error value. This process inevitably leads to overcurrent due to the excessively large error of the duty cycle value, which forms a potential danger to electronic components in the power grid, thereby increasing the risk of electricity use. In the present application, when the current is overcurrent, the power factor compensation circuit controls the switching device to be in an off state, so that the current in the power grid becomes smaller and the current returns to below the first threshold value. At this time, the power factor compensation circuit does not stop running, but no longer outputs the duty cycle value to control the switching device to turn on and off. The power factor compensation circuit continues to calculate the duty cycle value according to the output current in the power grid and the voltage of the load circuit, and limits the duty cycle value. This is because when the switching device is in an off state, the duty cycle value calculated by the power factor compensation circuit according to the output current in the power grid and the voltage of the load circuit will be large, and if it is used again, it will cause the current in the power grid to be too large. Therefore, the duty cycle value is limited to obtain a limited duty cycle value, and when the input current is greater than or equal to the second threshold value and less than the first threshold value, the limited duty cycle value is used to control the switching device to periodically turn on and off, which on the one hand avoids the stage of closing and restarting the power factor compensation circuit, and naturally avoids the overcurrent caused by the restart. On the other hand, the embodiments of the present application limit the excessively large duty cycle value calculated during the switching device being in an off state, which also avoids the overcurrent caused by the power factor compensation circuit running all the time.

[0009] Finally, the duty cycle value used by the switch device before the input current value reaches the first threshold value is taken as the duty cycle value threshold. That is, the duty cycle value threshold is determined according to the normal duty cycle value used before, which makes the duty cycle value threshold more reasonable to limit the calculated duty cycle value, causes the error of the limited duty cycle value to be small, and can avoid the current over-limit generated when the switch device is periodically turned on and off using the duty cycle value.

[0010] In an embodiment of the present application, the duty cycle value threshold is calculated according to the duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold value, including: taking the duty cycle value used by the switch device when the input current value reaches the first threshold value as the duty cycle value threshold.

[0011] In an embodiment of the present application, the duty cycle value used by the switch device when the input current value reaches the first threshold value is taken as the duty cycle value threshold. That is, the latest generated duty cycle value is taken as the duty cycle value threshold in time, which makes the duty cycle value threshold more consistent with the current operation of the power grid, and also closer to the situation of the power grid during the calculation of the duty cycle value when the switch device is in the off state. Using it to limit the duty cycle value can further reduce the error of the duty cycle value, and make the limited duty cycle value more accurate.

[0012] In an embodiment of the present application, the duty cycle value threshold is calculated according to the duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold value, including: taking the duty cycle value used by the switch device when the input current value reaches the first threshold value as the duty cycle value threshold.

[0013] In an 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 inductor module, and the voltage instruction indicating the required voltage of the load circuit. The duty cycle value can control the size and phase of the input current by periodically turning on and off the switch device, so that the phase of the current waveform and the voltage waveform of the input current is consistent, thereby increasing the efficiency of electric energy utilization. The duty cycle value threshold is an acceptable error of the duty cycle value, which is taken as the duty cycle value threshold of the duty cycle value to limit the error of the duty cycle value from being too large, and to avoid causing the current to be over-limit. The safety of power supply of the power grid is further improved.

[0014] In an 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 instruction indicating the voltage required by the load circuit, and the calculation includes: correcting the required amplitude of the input current according to the difference between the voltage instruction and the load voltage; correcting the required phase of the input current according to the phase information of the load voltage and the phase information of the input current; and calculating the duty cycle value according to the required amplitude of the input current and the required phase of the input current.

[0015] In an embodiment 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 known, that is, the size of the required voltage value of 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 required voltage value of 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 of the input current and the required phase of the input current. The amplitude and phase of the input current tend to the required phase and amplitude of the input current by controlling the periodic on-off of the switching device through the duty cycle value. In this way, the duty cycle value can be obtained faster and more directly.

[0016] In an embodiment of the present application, if the input current is greater than or equal to the second threshold value and less than the first threshold value, the on-off of the switching device is controlled according to the limited duty cycle value, and the second threshold value is less than the first threshold value, which includes: controlling the on-off of the switching device according to the latest obtained limited duty cycle value.

[0017] In an embodiment of the present application, if the input current is greater than or equal to the second threshold value and less than the first threshold value for a set time length, the on-off of the switching device is controlled according to the limited duty cycle value. This avoids the input current repeatedly at the first threshold value, which causes the operation mode of the switching device to change repeatedly and increases the calculation burden.

[0018] In an embodiment of the present application, if the input current is greater than or equal to the second threshold value and less than the first threshold value, the on-off of the switching device is controlled according to the limited duty cycle value, and the second threshold value is less than the first threshold value, which includes: controlling the on-off of the switching device according to the latest obtained limited duty cycle value.

[0019] In an embodiment of the present application, the latest obtained limited duty cycle value is more suitable for the current situation of the power factor compensation circuit, and the latest obtained limited duty cycle value can better control the on-off of the switching device, avoiding that the current is over limited due to the error of the limited duty cycle value.

[0020] In one embodiment of the present application, the first threshold is determined according to the maximum load current of each electronic component in the power grid where the power factor compensation circuit is located.

[0021] In one embodiment of the present application, the first threshold is determined according to the maximum load current of each electronic component in the power grid where the power factor compensation circuit is located, which can maximize the protection of each electronic component from being damaged.

[0022] In one embodiment of the present application, the power supply is an alternating current power supply, and the power factor compensation circuit further comprises a rectifier 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 switching device is electrically connected to the first output end of the rectifier module through an inductor module, and the second end of the switching device is electrically connected to the second output end of the rectifier module.

[0023] In one embodiment of the present application, when the power supply is an alternating current power supply, the power factor compensation circuit further comprises a rectifier module, which is used to convert the alternating current generated by the alternating current power supply into periodic direct current, which 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.

[0024] In one embodiment of the present application, the power factor compensation circuit is used to control the variable frequency motor.

[0025] In one embodiment 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.

[0026] In a third aspect, in one embodiment of the present application, a control method of a power factor compensation circuit is provided. The circuit includes a switching device, a first end of the switching device being electrically connected to a first end of a power supply through an inductor 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; the control method includes: if an input current of the inductor module reaches a first threshold value, controlling the switching device to remain in an off state; calculating a duty cycle threshold value according to a duty cycle value of a pulse width adjustment signal before the input current reaches the first threshold value; limiting and adjusting a duty cycle value obtained during the switching device remaining in the off state according to the duty cycle threshold value to obtain a limited duty cycle value; if the input current is greater than or equal to a second threshold value and less than the first threshold value, controlling the switching device to be turned on and turned off according to the limited duty cycle value, the second threshold value being less than the first threshold value.

[0027] In the embodiment of the present application, since the power factor compensation circuit restarts, there is a process of recalculating the duty cycle value. In this process, it is inevitable to use a duty cycle value with a large error to control the switching device to be periodically turned on and turned off, so as to correct the duty cycle value according to the error value. This process inevitably leads to overcurrent due to the large error of the duty cycle value, which forms a potential danger to electronic components in the power grid, and further increases the risk of power consumption. In the present application, when the current is overcurrent, the power factor compensation circuit controls the switching device to be in the off state, so as to make the current in the power grid smaller and return to below the first threshold value. At this time, the power factor compensation circuit does not stop running, but no longer outputs the duty cycle value to control the switching device to be turned on and turned off. The power factor compensation circuit continues to calculate the duty cycle value according to the output current in the power grid and the voltage of the load circuit, and limits the duty cycle value. This is because when the switching device is in the off state, the duty cycle value calculated by the power factor compensation circuit according to the output current in the power grid and the voltage of the load circuit will be too large, and if it is used again, it will cause the current in the power grid to be too large. Therefore, the duty cycle value is limited to obtain a limited duty cycle value, and when the input current is greater than or equal to the second threshold value and less than the first threshold value, the limited duty cycle value is used to control the switching device to be periodically turned on and turned off. On the one hand, this avoids the stage of closing and restarting the power factor compensation circuit, and naturally avoids the overcurrent caused by the restart. On the other hand, the embodiment of the present application limits the too large duty cycle value calculated during the switching device being in the off state, which also avoids the overcurrent caused by the power factor compensation circuit being always running.

[0028] Other features and advantages of the present application will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the application.

[0029] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application, as claimed. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and serve to explain the principles of the application. It is

[0031] Figure 1 A circuit diagram of a power factor compensation circuit according to one embodiment of the application is shown.

[0032] Figure 2 A schematic diagram of a power factor compensation circuit according to one embodiment of the application is shown.

[0033] Figure 3 A flowchart of controlling a power factor compensation circuit according to one embodiment of the application is shown.

[0034] Figure 4 A flowchart of clipping a duty cycle value obtained during a period when a switching device is kept in an open state according to a duty cycle value threshold according to one embodiment of the application is shown.

[0035] Figure 5 A flowchart of calculating a duty cycle value according to a load voltage of a load circuit, a phase of an input current of an inductor module, and a voltage command indicative of a voltage required by the load circuit according to one embodiment of the application is shown.

[0036] Figure 6 A schematic diagram of a power factor compensation circuit according to another embodiment of the application is shown.

[0037] REFERENCE NUMERALS

[0038] 1: power supply (AC power supply);

[0039] 2: inductor module;

[0040] 3: switching device;

[0041] 4: load circuit;

[0042] 41: diode;

[0043] 42: capacitor module;

[0044] 43: energy consuming module; DETAILED DESCRIPTION

[0045] 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.

[0046] 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

[0047] 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 therefore to be understood as functional illustrations of example implementations, and not as a mechanical form of the example implementations.

[0048] The flow diagrams shown in the drawings are merely examples of possible flow diagrams and are not necessarily meant to include all of the steps, operations, or processes, or in the order described. For example, some operations / steps can be broken down further, while some operations / steps can be combined or partially combined, and thus the actual order of execution can vary from what is described.

[0049] 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.

[0050] 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 power factor compensation module 100, a power supply module 200, a control module 300, and a power factor compensation module 400. Figure 1As shown, the power factor compensation circuit includes an AC power supply 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.

[0051] The first end of the switching device 3 is electrically connected to the first end of the power supply 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 supply 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.

[0052] 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 supply through the load circuit 43 or the switching device 3.

[0053] 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 supply without passing through the load circuit 4.

[0054] When the switching device 3 is opened, first, the power supply 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 supply, that is, 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.

[0055] When the switching device 3 is frequently turned on and off, the input current is pulled up and supplies power 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.

[0056] The control scheme for the power factor compensation circuit mainly adopts a dual closed-loop control consisting of an outer voltage loop and an inner current loop. The inner current loop forces the input current to track the waveform of the input voltage, resulting in a sinusoidal waveform. The outer voltage loop keeps the output voltage above the peak value of the input voltage and also stabilizes the output voltage.

[0057] Please see Figure 3 , Figure 3 A flowchart illustrating a control power factor compensation circuit according to an embodiment of this application is shown. This application embodiment provides a control step for configuring a power factor compensation circuit controller, including:

[0058] Step S310: If the input current of the inductor module reaches the first threshold, then control the switching device to remain in the off state.

[0059] Step S320: Calculate the duty cycle threshold based on the duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold.

[0060] Step S330: Based on the duty cycle threshold, the duty cycle value obtained during the period when the switching device remains in the off state is limited and adjusted to obtain the limited duty cycle value.

[0061] Step S340: If the input current is greater than or equal to the second threshold and less than the first threshold, then the switching device is controlled to switch on and off according to the duty cycle limit value, where the second threshold is less than the first threshold.

[0062] The above four steps will be described in detail below.

[0063] In step S310, during grid operation, the magnitude of the input current of inductor module 3 is monitored. When the input current exceeds a first threshold, it indicates that the input current is too large. Continuing to compensate the input current through the power factor compensation circuit will cause the input current to continuously exceed the limit, i.e., continuously exceed the first threshold, damaging the electronic components in the grid. Therefore, the switch device 3 is controlled to remain in the open state, i.e., the power factor compensation effect on the input current is stopped. It should be noted that the magnitude of the input current can be obtained by setting a sampling circuit. There are no restrictions on the configuration of the sampling circuit. On the other hand, it should be noted that the first threshold can be preset or obtained from the parameters of various electronic components in the grid, as well as environmental parameters such as the current grid temperature, humidity, and light intensity.

[0064] For example, the maximum load current that the weakest electronic component in the power grid can bear is calculated as the first threshold according to the parameters of the weakest electronic component 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 first threshold. In another embodiment of the present application, the product of the maximum current that the weakest electronic component can bear and a safety factor (the safety factor is greater than 0 and less than 1) is taken as the first threshold. This can avoid damaging the weakest electronic component to the greatest extent.

[0065] It should be noted that the first threshold refers to the current value that can cause damage to the electronic components in the power grid. The second threshold refers to the current value that can ensure that the electronic components in the power grid are not damaged.

[0066] In step S320, the obtained duty cycle value is limited to obtain a limited duty cycle value. Before the limited duty cycle value is obtained, the first threshold needs to be calculated. The type, circuit layout, and number of electronic components in each power grid are different. Therefore, the duty cycle threshold needs to be calculated according to the actual operation of each power grid. In an embodiment of the present application, the duty cycle threshold is calculated according to the duty cycle value used when the power grid is stably operated. For example, the average of all duty cycle values used when the input current of the power grid is in a preset fluctuation range is taken as the duty cycle threshold. The preset fluctuation range can be self-defined, and the purpose is to filter the duty cycle values used when the input current is relatively stable.

[0067] In an embodiment of the present application, the initial current is the duty cycle value used by the switch device before the input current value reaches the first threshold. That is, the duty cycle threshold is determined according to the previously normally used duty cycle value. This makes the duty cycle threshold more reasonable for limiting the calculated duty cycle value, so that the error of the limited duty cycle value is small, and the over-limit current generated when the switch device is periodically turned on and off by using the duty cycle value can be avoided.

[0068] In another embodiment of the present application, the input current value reaches the first threshold when the switch device uses the duty cycle value, which is taken as the duty cycle threshold. That is, the latest generated duty cycle value is taken as the duty cycle threshold in terms of time sequence. This makes the duty cycle threshold more consistent with the current operation of the power grid, and also closer to the situation of the power grid when the duty cycle value is calculated during the off state of the switch device. Using the duty cycle threshold to limit the duty cycle value can further reduce the error of the duty cycle value.

[0069] In step S330, during the switch device 3 is in the off state, the operation of the power factor compensation circuit is not closed, only the output of the duty cycle value calculated by the power factor compensation circuit is stopped, that is, the power factor compensation circuit no longer controls the on-off of the switch device 3. But the power factor compensation circuit still continues to calculate the duty cycle value, and in this process, since the power factor compensation circuit will stop compensating the input current, it will cause the power factor compensation circuit to determine that the compensation current needs to be increased according to the current size at this time, thereby causing the duty cycle value to become larger. It cannot be used after the input current returns to normal, which will cause the input current after recovery to continue to be limited, damaging the electronic components in the power grid. Therefore, the duty cycle value obtained during the switch device 3 is in the off state is limited to obtain the limited duty cycle value, and the switch device 3 is controlled to be periodically turned on and off by the limited duty cycle value, so that the current is not limited.

[0070] Please refer to Figure 4 , Figure 4 The flow chart of limiting and adjusting the duty cycle value obtained during the switch device is in the off state according to the duty cycle value threshold according to an embodiment of the present application is shown. The embodiment of the present application provides step 330 of limiting and adjusting the duty cycle value obtained during the switch device is in the off state according to the duty cycle value threshold to obtain the limited duty cycle value, comprising:

[0071] In step S331, the duty cycle value is calculated according to the load voltage of the load circuit, the phase of the input current of the inductor module, and the voltage instruction indicating the required voltage of the load circuit. The load circuit voltage is obtained, such as using a voltage sensor or a voltmeter to measure the load voltage. The voltage error is calculated, which is the difference between the voltage instruction and the load voltage, which is used to determine the gain of the power factor compensation circuit, which is a proportional factor used to convert the voltage error into the adjustment amount of the duty cycle. 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.

[0076] In step S332, if the duty cycle value is greater than the duty cycle value threshold, the duty cycle value threshold is taken as the limited duty cycle value corresponding to the duty cycle value.

[0077] In step S333, if the duty cycle value is less than or equal to the duty cycle value threshold, the duty cycle value itself is taken as the limited duty cycle value.

[0078] The above three steps are described in detail below.

[0079] In step S331, the duty cycle value is calculated according to the load voltage of the load circuit, the phase of the input current of the inductor module, and the voltage instruction indicating the required voltage of the load circuit. The load circuit voltage is obtained, such as using a voltage sensor or a voltmeter to measure the load voltage. The voltage error is calculated, which is the difference between the voltage instruction and the load voltage, which is used to determine the gain of the power factor compensation circuit, which is a proportional factor used to convert the voltage error into the adjustment amount of the duty cycle. 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.

[0076] In another embodiment of the present application, PID (Proportion-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.

[0077] In step S332, if the duty cycle value is greater than the duty cycle value threshold, the duty cycle value threshold is taken as the limited duty cycle value corresponding to the duty cycle value. The duty cycle value threshold refers to the duty cycle value that can not cause the input current to be over limited.

[0078] In step S333, if the duty cycle value is greater than the duty cycle value threshold, the duty cycle value threshold is taken as the limited duty cycle value corresponding to the duty cycle value.

[0079] In the 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 inductor module, and the voltage instruction indicating the required voltage of the load circuit. The duty cycle value can control the size and phase of the input current by periodically turning on and off the switching device, so that the phase of the current waveform and the voltage waveform of the input current is consistent, thereby increasing the efficiency of electric energy utilization. The duty cycle value threshold is an error acceptable duty cycle value, which is taken as the duty cycle value threshold of the duty cycle value to limit the duty cycle value error to be too large, avoiding causing the current to be over limited, and further improving the safety of power supply.

[0080] Please refer to Figure 5 , Figure 5 The flow chart for calculating the duty cycle value according to the load voltage of the load circuit, the phase of the input current of the inductor module, and the voltage instruction 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 step S331 for calculating the duty cycle value according to the load voltage of the load circuit, the phase of the input current of the inductor module, and the voltage instruction indicating the required voltage of the load circuit, comprising:

[0081] Step S501, correcting the required amplitude of the input current according to the difference between the voltage instruction and the load voltage;

[0082] Step S502, correcting the required phase of the input current according to the phase information of the load voltage and the phase information of the input current;

[0083] Step S503, calculating the duty cycle value according to the required amplitude of the input current and the required phase of the input current.

[0084] The above three steps are described in detail below.

[0085] In step S501, the required amplitude of the input current is corrected according to the difference between the voltage instruction and the load voltage. 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 known, that is, the required size of the load voltage value 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 based on the physical relationship between the voltage and the current, the required amplitude of the input current can be determined according to the size of the required voltage value of the load voltage.

[0086] In step S502, the required phase of the input current is determined according to the phase information of the load voltage and the phase information of the input current.

[0087] In step S503, the duty cycle value is calculated according to the required amplitude and the required phase of the input current, and the switch device is periodically turned on and off through the duty cycle value, so that the amplitude and the phase of the input current tend to the required phase and the required amplitude of the input current.

[0088] Through the method provided by the embodiment of the present application, the duty cycle value can be obtained more quickly and directly.

[0089] In step S340, the switch device 3 is periodically turned on and off by limiting the duty cycle value, the function of the power factor compensation circuit to control the switch device to be periodically turned on and off is restored, and the problem of over-limit of the input current caused by restarting of the power factor compensation circuit is avoided.

[0090] In the embodiments of the present application, since the power factor compensation circuit restarts, there is a process of recalculating the duty cycle value, and in this process, the switch device is inevitably controlled to periodically turn on and off with a relatively large error duty cycle value to correct the duty cycle value according to the error value. This process inevitably leads to overcurrent due to the excessively large error of the duty cycle value, which forms a potential danger to the electronic components in the power grid, thereby increasing the risk of electricity use. In the present application, when the current is over, the control switch device is in an off state to make the current in the power grid smaller and return to below the first threshold value. At this time, the power factor compensation circuit does not stop running, but no longer outputs the on-off control of the switch device. The power factor compensation circuit continues to calculate the duty cycle value according to the output current in the power grid and the voltage of the load circuit, and limits the duty cycle value. This is because when the switch device is in the off state, the duty cycle value calculated by the power factor compensation circuit according to the output current in the power grid and the voltage of the load circuit will be large, and if it is used again, it will cause the current in the power grid to be too large. Therefore, the duty cycle value is limited to obtain a limited duty cycle value, and when the input current is greater than or equal to the second threshold value and less than the first threshold value, the switch device is controlled by using the limited duty cycle value to periodically turn on and off. On the one hand, this avoids the stage of restarting the power factor compensation circuit, and naturally avoids the overcurrent caused by restarting. On the other hand, by limiting the excessively large duty cycle value calculated during the off state of the switch device, the application embodiment also avoids the overcurrent caused by the continuous operation of the power factor compensation circuit.

[0091] Finally, the duty cycle value used by the switch device before the input current value reaches the first threshold value is taken as the duty cycle threshold value. That is, the duty cycle threshold value is determined according to the previously normally used duty cycle value, which makes the duty cycle threshold value more reasonable to limit the calculated duty cycle value, so that the limited duty cycle value has a small error and can avoid the overcurrent caused by using the duty cycle value to control the switch device to periodically turn on and off.

[0092] In an embodiment of the present application, when the input current is greater than or equal to the second threshold value and less than the first threshold value for a set time length, the switch device is controlled to turn on and off according to the limited duty cycle value. In the embodiments of the present application, if the input current is greater than or equal to the second threshold value and less than the first threshold value for a set time length, the switch device is controlled to turn on and off according to the limited duty cycle value. This avoids the input current repeatedly at the first threshold value, which causes the operation mode of the switch device to change repeatedly and increases the calculation burden.

[0093] In another embodiment of the present application, the switch device is controlled to turn on and off according to the latest obtained limited duty cycle value.

[0094] In the embodiment of the present application, the newly acquired limit duty cycle value is more consistent with the current situation of the power factor compensation circuit, and the newly acquired limit duty cycle value can better control the on-off of the switching device, thereby avoiding over-limit of the current caused by errors of the duty cycle value.

[0095] In an embodiment of the present application, referring to Figure 6 , Figure 6 A schematic diagram of a power factor compensation circuit according to another embodiment of the present application is shown. When the power supply is an alternating current power supply, the power factor compensation circuit further comprises a rectification module 5 for converting alternating current generated by the alternating current power supply 1 into 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 inductor module 2, and the second end of the switching device is electrically connected to the second output end of the rectification module 5.

[0096] This makes the power factor compensation circuit in the embodiment of the present application can be universally applied to different circuits, greatly increasing the range of application of the present application.

[0097] In one embodiment of the present application, there is also a storage medium carrying the power factor compensation circuit and the control method thereof. The storage medium shown in the embodiments can be a computer readable signal medium or a computer readable storage medium or any combination of the two. The computer readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination of the above. More specific examples of the computer readable storage medium can include, but are not limited to, an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (Compact Disc Read-Only Memory, CD-ROM), an optical storage device, a 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 a program that can be used by or in conjunction with an instruction execution system, device or apparatus. In the present application, the computer readable signal medium can include a data signal carried in a baseband or as a part of a carrier wave, which carries computer readable program code. Such a propagated data signal can take various forms, including but not limited to an electromagnetic signal, an optical signal or any suitable combination of the above. The computer readable signal medium can also be any storage threshold other than the computer readable storage medium, which can send, propagate or transmit a program for use by or in conjunction with an instruction execution system, device or apparatus. The program code contained on the storage threshold can be transmitted by any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination of the above.

[0098] The flowcharts and block diagrams in the drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present application. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment, or a portion of code that contains one or more executable instructions for implementing the specified functions. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur in a different order than that shown in the figures. For example, two blocks that are shown in succession can actually be executed substantially concurrently, or they can sometimes be executed in reverse order, depending on the functionality involved. It should also be noted that each block in the flowcharts or block diagrams, and combinations of blocks in the flowcharts or block diagrams, can be implemented by special-purpose hardware-based systems that perform the specified functions or operations, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0099] It should be noted that, although several modules or units for a device for action execution are mentioned in the above detailed description, such a division is not mandatory. Indeed, according to an embodiment of the application, the features and functionalities of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functionalities of one module or unit described above can be further divided into several modules or units embodied.

[0100] Those skilled in the art can easily understand, through the above description of the embodiments, that the example embodiments described herein can be implemented by software, or by software in combination with necessary hardware. Therefore, the technical solutions according to the embodiments of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a U disk, a mobile hard disk, etc.) or a network, and includes several instructions to make a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) execute the methods according to the embodiments of the present application.

[0101] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the present application cover any and all variations of the application that come within the scope of the present application, along with all of the equivalents thereof. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0102] It should be understood that the present application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the present application. The scope of the present 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: If the input current of the inductor module reaches the first threshold, the switching device is controlled to remain in the off state. The duty cycle threshold is calculated based on the duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold. Based on the duty cycle threshold, the duty cycle value obtained during the period when the switching device remains in the off state is limited and adjusted to obtain a limited duty cycle value; If the input current is greater than or equal to the second threshold and less than the first threshold, the switching device is controlled to switch on and off according to the duty cycle limit value, wherein the second threshold is less than the first threshold.

2. The circuit according to claim 1, characterized in that, The step of calculating the duty cycle threshold based on the duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold includes: When the input current value reaches the first threshold, the duty cycle value used by the switching device is used as the duty cycle threshold value.

3. The circuit according to claim 1, characterized in that, The step of limiting and adjusting the duty cycle value obtained during the period when the switching device remains in the off state, based on the duty cycle value threshold, to obtain a limited duty cycle value 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. If the duty cycle value is greater than the duty cycle value threshold, then the duty cycle value threshold is used as the limit duty cycle value corresponding to the duty cycle value; If the duty cycle value is less than or equal to the duty cycle threshold, then the duty cycle value itself is used as the limit duty cycle value.

4. The circuit according to claim 3, characterized in that, The step of calculating the duty cycle value 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 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.

5. The circuit according to claim 1, characterized in that, If the input current is greater than or equal to the second threshold and less than the first threshold, then controlling the switching device to turn on and off according to the limited duty cycle value includes: If the input current is greater than or equal to the second threshold and less than the first threshold for a set duration, the switching device is controlled to switch on and off according to the limited duty cycle value.

6. The circuit according to claim 1, characterized in that, If the input current is greater than or equal to a second threshold and less than a first threshold, then the switching device is controlled to switch on and off according to the limited duty cycle value, wherein the second threshold is less than the first threshold, including: The switching device is controlled to turn on and off according to the latest obtained duty cycle limit value.

7. The circuit according to claim 1, characterized in that, The first threshold is determined based on the maximum load current of each electronic component in the power grid where the power factor compensation circuit is located.

8. 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.

9. A household appliance, characterized in that, Including variable frequency motors; and The 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.

10. A control method for 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; The control method includes: If the input current of the inductor module reaches the first threshold, the switching device is controlled to remain in the off state. The duty cycle threshold is calculated based on the duty cycle value of the pulse width adjustment signal before the input current reaches the first threshold. Based on the duty cycle threshold, the duty cycle value obtained during the period when the switching device remains in the off state is limited and adjusted to obtain a limited duty cycle value; If the input current is greater than or equal to the second threshold and less than the first threshold, the switching device is controlled to switch on and off according to the duty cycle limit value, wherein the second threshold is less than the first threshold.

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