Voltage sampling circuit and household electrical appliance

Abstract

The utility model provides a voltage sampling circuit and a household electrical appliance, the voltage sampling circuit comprises a filter circuit, a rectification circuit, a load circuit and a sampling circuit, the sampling circuit comprises a first voltage division circuit, a second voltage division circuit and an operational amplifier module, the first voltage division circuit comprises a plurality of resistors, and the second voltage division circuit comprises a plurality of resistors; a first sampling point can be arranged between any resistors in the first voltage division circuit, the second voltage division circuit comprises a plurality of resistors, and a second sampling point is arranged between any resistors in the second voltage division circuit. The technical problem that the alternating current power supply voltage change signal cannot be accurately acquired is solved.

Description

Technical Field

[0001] The present application relates to the technical field of voltage sampling, and in particular to a voltage sampling circuit and a household appliance. Background Art

[0002] Many power loads in the power grid are inductive loads, and these inductive loads need to absorb both useful power and useless power from the power system during operation. To this end, a common approach is to use power factor compensation. Power factor compensation, that is, installing parallel capacitor reactive power compensation equipment 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 and in the transmission line process. When determining the power factor compensation, it is necessary to accurately collect the voltage change signal of the AC power supply. If the voltage change signal is not accurate enough, the effect of power factor compensation will be greatly reduced.

[0003] Therefore, how to accurately collect the voltage change signal of the AC power supply is a problem that urgently needs to be solved. Summary of the invention

[0004] In order to solve the above technical problems, an embodiment of the present application provides a voltage sampling circuit.

[0005] In a first aspect, in one embodiment of the present application, a voltage sampling circuit is provided, comprising: a filtering circuit, wherein the filtering circuit is connected to an AC power supply and is used to filter the AC power supply; a rectifier circuit, wherein a first input end of the rectifier circuit is connected to a first output end of the filtering circuit, and a second input end of the rectifier circuit is connected to a second output end of the filtering circuit, and the rectifier circuit is used to convert the AC power output by the filtering circuit into DC power; a load circuit, wherein the load circuit is connected to the output end of the filtering circuit; and a sampling circuit, wherein a first end of the sampling circuit is connected between a first output end of the filtering circuit and a first input end of the rectifier circuit, and a second end of the sampling circuit is connected between a second output end of the filtering circuit and a second input end of the rectifier circuit. The sampling circuit is used to collect and output a voltage change signal; wherein the sampling circuit includes a first voltage divider circuit, a second voltage divider circuit, and an operational amplifier module; a plurality of resistors are respectively provided in the first voltage divider circuit and the second voltage divider circuit, the first end of the first voltage divider circuit serves as the first end of the sampling circuit, the second end of the second voltage divider circuit serves as the second end of the sampling circuit, and the second end of the first voltage divider circuit and the second end of the second voltage divider circuit are grounded; the first sampling point in the first voltage divider circuit is connected to the first input end of the operational amplifier module, the second sampling point in the second voltage divider circuit is connected to the second input end of the operational amplifier module, the first sampling point is provided between any two resistors in the first voltage divider circuit, and the second sampling point is provided between any two resistors in the second voltage divider circuit.

[0006] In the embodiment of the present application, the present application first sets a filter circuit to filter the interference signal in the voltage sampling circuit. On the basis of using the filter circuit, the present application further sets a first voltage divider circuit and a second voltage divider circuit, and the first voltage divider circuit and the second voltage divider circuit are respectively connected to two wires of the AC power supply, such as the neutral wire and the live wire, to obtain the voltage on the two wires.

[0007] After the voltage is divided by the first voltage divider circuit and the second voltage divider circuit, the voltage difference between the first sampling point in the first voltage divider circuit and the second sampling point in the second voltage divider circuit is obtained through the operational amplifier module as a voltage change signal. This circuit can also be called a differential sampling circuit. Since the voltage signals of the first sampling point and the second sampling point are connected to the same AC power supply, if the two voltage signals have the same interference signal, it is also called a common-mode interference signal. This will eliminate the common-mode interference signal in the two voltage signals when the difference between the two voltage signals is obtained, so that the voltage change signal output by the operational amplifier module is not affected by the common-mode interference signal. Combined with the function of removing interference signals by the filter circuit, the obtained voltage change signal has a higher accuracy.

[0008] In some embodiments of the present application, based on the aforementioned scheme, the first voltage divider circuit includes: a first resistance unit and a second resistance unit; the second voltage divider circuit includes a third resistance unit and a fourth resistance unit; wherein the first end of the first resistance unit is connected to the first end of the first voltage divider circuit, and the second end of the first resistance unit is connected to the first end of the second resistance unit; the second end of the second resistance unit is grounded; the first end of the third resistance unit is connected to the first end of the second voltage divider circuit, and the second end of the third resistance unit is connected to the first end of the fourth resistance unit; the second end of the fourth resistance unit is grounded.

[0009] In an embodiment of the present application, multiple groups of resistor units are set to share the voltage to reduce the voltage connected to the first sampling point in the first voltage divider circuit and the second sampling point in the second voltage divider circuit, thereby reducing the current output at the first sampling point and the second sampling point to prevent damage to the operational amplifier module.

[0010] In some embodiments of the present application, based on the aforementioned scheme, the operational amplifier module includes: a fifth resistance unit, a sixth resistance unit, and an operational amplifier; wherein the first end of the fifth resistance unit is connected to the first sampling point, and the second end of the fifth resistance unit is connected to the positive input terminal of the operational amplifier; the first end of the sixth resistance unit is connected to the second sampling point, and the second end of the sixth resistance unit is connected to the negative input terminal of the operational amplifier.

[0011] In the embodiment of the present application, since the current flowing through the first voltage divider circuit and the second voltage divider circuit is too small, the voltage signal difference between the first sampling point and the second sampling point will also be very small, so the first sampling point and the second sampling point are connected to the two input terminals of the operational amplifier via the fifth resistor unit and the sixth resistor unit respectively, and the voltage difference between the first sampling point and the second sampling point is automatically calculated and amplified via the operational amplifier. The above circuit greatly improves the automatic effect of the above circuit in obtaining the voltage change signal.

[0012] In some embodiments of the present application, based on the aforementioned scheme, the operational amplifier module also includes: a seventh resistance unit, a first end of the seventh resistance unit is connected to the negative input terminal of the operational amplifier, and a second end of the seventh resistance unit is connected to the output terminal of the operational amplifier; a first capacitor, a first end of the first capacitor is connected to the negative input terminal of the operational amplifier, and a second end of the first capacitor is connected to the output terminal of the operational amplifier.

[0013] In the embodiment of the present application, in order to address the situation where the input voltages at the two input terminals of the operational amplifier are unstable, a resistor and a capacitor are connected in parallel to the negative input terminal of the operational amplifier to stabilize the input voltages at the two input terminals of the operational amplifier.

[0014] In some embodiments of the present application, based on the aforementioned scheme, the operational amplifier module also includes: an eighth resistance unit, the first end of the eighth resistance unit is connected to the auxiliary power supply, the second end of the eighth resistance unit is respectively connected to the first end of the ninth resistance unit, the first end of the second capacitor, and the positive input end of the operational amplifier; the second ends of the ninth resistance unit and the second capacitor are grounded.

[0015] In the embodiment of the present application, the circuit described in the above embodiment is connected to the positive input terminal of the operational amplifier, so that the operational amplifier can always provide positive feedback, avoiding the occurrence of negative feedback. Because if positive feedback and negative feedback occur at the same time, the negative feedback will cause the gain of the operational amplifier to decrease, the frequency response to deteriorate, and the phase delay to increase.

[0016] In some embodiments of the present application, based on the aforementioned scheme, the filtering circuit includes: a differential mode interference circuit, a first end of the differential mode interference circuit is connected to the first end of the AC power supply, and a second end of the differential mode interference circuit is connected to the second end of the AC power supply.

[0017] In one embodiment of the present application, a differential mode interference circuit is provided to eliminate differential mode interference generated by a voltage sampling circuit, thereby making the collected voltage change signal more accurate.

[0018] In some embodiments of the present application, based on the aforementioned scheme, the filtering circuit includes: a common-mode interference circuit, wherein a first input end of the common-mode interference circuit is connected to a first end of the AC power supply, a second input end of the common-mode interference circuit is connected to a second end of the AC power supply, a first output end of the common-mode interference circuit is connected to a first input end of the rectifier circuit, and a second output end of the common-mode interference circuit is connected to a second input end of the rectifier circuit.

[0019] Common-mode interference refers to the interference voltage signal having the same amplitude and direction on two wires. By collecting the voltage change signal through the differential sampling circuit, a part of the common-mode interference signal can be eliminated, and then the common-mode interference signal in the circuit can be removed through the common-mode interference circuit. Under the double removal effect, the common-mode interference signal in the circuit can be removed to the greatest extent.

[0020] In some embodiments of the present application, based on the aforementioned scheme, the filtering circuit also includes: a third capacitor, a first end of the third capacitor is connected between the first end of the AC power supply and the first input end of the common-mode interference circuit, and a second end of the third capacitor is connected between the second end of the AC power supply and the second input end of the common-mode interference circuit; a fourth capacitor, a first end of the fourth capacitor is connected between the first output end of the common-mode interference circuit and the first end of the sampling circuit, and a second end of the fourth capacitor is connected between the second output end of the common-mode interference circuit and the second end of the sampling circuit.

[0021] In the embodiment of the present application, not only is a differential mode interference circuit provided to eliminate differential mode interference signals, but also a third capacitor and a fourth capacitor are provided to eliminate common mode interference signals in the voltage sampling circuit, so that the collected voltage change signal is more accurate.

[0022] In some embodiments of the present application, based on the aforementioned scheme, the circuit also includes: a power factor compensation circuit, used to adjust the voltage and / or current output by the rectifier circuit according to the voltage change signal obtained by the sampling circuit, the first end of the power factor compensation circuit is connected between the first output end of the rectifier circuit and the first end of the load circuit, and the second end of the power factor compensation circuit is connected between the second output end of the rectifier circuit and the second end of the load circuit.

[0023] In the embodiment of the present application, based on the collected accurate voltage change signal, the power factor compensation circuit can output voltage and / or current more accurately, thereby synchronizing the current change and voltage change in the load circuit, reducing the useless power in the load circuit and increasing the useful power. Finally, the load circuit uses the electric energy more efficiently.

[0024] In a second aspect, in some embodiments of the present application, a household appliance comprises: a variable frequency motor; and a voltage sampling circuit as described in any of the above embodiments, wherein the variable frequency motor is contained in the load circuit, and the voltage change signal output by the voltage sampling circuit is used for pulse width modulation to control the variable frequency motor.

[0025] In the embodiments of the present application, the above-mentioned technical solution can be applied to any household appliance with a variable frequency motor, thereby reducing the useless power generated by the variable frequency motor during operation, thereby increasing the useful power of the variable frequency motor, making the household appliances use electric energy more efficiently, and increasing the energy-saving experience of household appliances for users.

[0026] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0027] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0029] Figure 1 A circuit diagram of a voltage sampling circuit according to an embodiment of the present application is shown.

[0030] Figure 2 A circuit diagram of a first voltage divider circuit and a second voltage divider circuit according to an embodiment of the present application is shown.

[0031] Figure 3 A circuit diagram of an operational amplifier module according to an embodiment of the present application is shown.

[0032] Figure 4 A circuit schematic diagram of a circuit having a voltage stabilizing function in an operational amplifier module according to an embodiment of the present application is shown.

[0033] Figure 5 A circuit diagram of a circuit for ensuring positive feedback of an operational amplifier according to an embodiment of the present application is shown.

[0034] Figure 6 A circuit schematic diagram of a differential mode interference circuit according to an implementation of the present application is shown.

[0035] Figure 7 A circuit schematic diagram of a common-mode interference circuit according to an implementation of the present application is shown.

[0036] Figure 8 A circuit schematic diagram including a differential mode interference circuit and a common mode interference circuit according to an implementation of the present application is shown.

[0037] Description of reference numerals:

[0038] 1: AC power supply;

[0039] 2: filter circuit: 210: differential mode interference circuit; 220: common mode interference circuit; 211: third capacitor; 212: fourth capacitor; 221: first inductor; 222: second inductor;

[0040] 3: Rectification circuit;

[0041] 4: Load circuit;

[0042] 5: sampling circuit; 510: first voltage divider circuit; 520: second voltage divider circuit; 530: operational amplifier module; 511: first resistance unit; 512: second resistance unit; 513: first sampling point; 521: third resistance unit; 522: fourth resistance unit; 523: second sampling point; 531: fifth resistance unit; 532: sixth resistance unit; 533: seventh resistance unit; 534a: eighth resistance unit; 534b: ninth resistance unit; 535: first capacitor; 536: second capacitor; 537: operational amplifier; 538: first external power supply; 539: auxiliary power supply; DETAILED DESCRIPTION

[0043] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0044] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other methods, components, steps, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0045] The flowcharts shown in the accompanying drawings are only exemplary illustrations and do not necessarily include all the contents and operations / steps, nor do they have to be executed in the described order. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined, so the actual execution order may change according to the actual situation. It should also be noted that the "multiple" mentioned in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0046] The terms "first", "second", "third", "fourth", etc. in the specification, claims and drawings of this application are used to distinguish different objects rather than to describe a specific order. The terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions.

[0047] In view of the technical problem that the prior art cannot accurately collect the voltage change signal of the AC power supply when determining the power factor compensation. The present application first sets a filter circuit 2 to filter the interference signal in the voltage sampling circuit. On the basis of using the filter circuit 2, the present application also sets a first voltage divider circuit 510 and a second voltage divider circuit 520, and the first voltage divider circuit 510 and the second voltage divider circuit 520 are respectively connected to two wires of the AC power supply 1, such as the neutral wire and the live wire, to obtain the voltage on the two wires.

[0048] After the voltage is divided by the first voltage divider circuit 510 and the second voltage divider circuit 520, the voltage difference between the first sampling point in the first voltage divider circuit 510 and the second sampling point in the second voltage divider circuit 520 is obtained through the operational amplifier module 530 as a voltage change signal. This circuit can also be called a differential sampling circuit. Since the voltage signals of the first sampling point and the second sampling point are connected to the same AC power supply 1, if the two voltage signals have the same interference signal, it is also called a common-mode interference signal. This will eliminate the common-mode interference signal in the two voltage signals when the difference between the two voltage signals is obtained, so that the voltage change signal output by the operational amplifier module 530 is not affected by the common-mode interference signal. Combined with the function of removing interference signals by the filter circuit 2, the obtained voltage change signal has a higher accuracy.

[0049] See also Figure 1 , Figure 1 FIG. 1 shows a circuit diagram of a voltage sampling circuit according to an embodiment of the present application. Figure 1 As shown, the voltage sampling circuit includes a filter circuit 2, a rectifier circuit 3, a load circuit 4, and a sampling circuit 5, wherein the sampling circuit may include: a first voltage divider circuit 510 and a second voltage divider circuit 520, and an operational amplifier module 530. The first voltage divider circuit 510 may include a plurality of resistors. A first sampling point 513 may be provided between any resistors in the first voltage divider circuit 510. The second voltage divider circuit 520 may include a plurality of resistors. A second sampling point 523 may be provided between any resistors in the second voltage divider circuit 520. It should be clear that the connection relationship between the plurality of resistors in the first voltage divider circuit 510 and the second voltage divider circuit 520 is a series connection.

[0050] As Figure 1The first end (L1) of the sampling circuit 5 shown can be connected between the first output end of the filter circuit 2 and the first input end of the rectifier circuit 3. The second end (N1) of the sampling circuit 5 can be connected between the second output end of the filter circuit 2 and the second input end of the rectifier circuit 3. The sampling circuit 5 can be used to collect voltage change signals at the first and second ends of the sampling circuit 5. The first end of the first voltage divider circuit 510 can serve as the first end of the sampling circuit 5. That is, the first end of the first voltage divider circuit 510 can coincide with the first end of the sampling circuit 5, both of which are L1. The second end of the first voltage divider circuit 510 can be grounded. The first end of the second voltage divider circuit 520 can serve as the second end of the sampling circuit 5. That is, the first end of the second voltage divider circuit 520 can coincide with the second end of the sampling circuit 5, both of which are N1.

[0051] In one embodiment of the present application, the first end of the first voltage divider circuit 510 can be connected between the first output end of the filter circuit 2 and the first input end of the rectifier circuit 3. The first voltage divider circuit 510 can obtain the voltage between the first output end of the filter circuit 2 and the first input end of the rectifier circuit 3. Voltage division can be performed by multiple resistors connected in series in the first voltage divider circuit 510 to prevent excessive voltage from damaging the operational amplifier module 530.

[0052] The first end of the second voltage divider circuit 520 can be connected between the second output end of the filter circuit 2 and the second input end of the rectifier circuit 3. The second voltage divider circuit 520 can obtain the voltage between the second output end of the filter circuit 2 and the second input end of the rectifier circuit 3. Voltage division can be performed by multiple resistors connected in series in the second voltage divider circuit 520 to prevent excessive voltage from damaging the operational amplifier module 530.

[0053] Further, by setting a first sampling point 513 and a second sampling point 523 on the first voltage divider circuit 510 and the second voltage divider circuit 520, respectively, the voltage signal of a certain resistor in the first voltage divider circuit 510 and the second voltage divider circuit 520 is obtained. The voltage signal at the first sampling point 513 can represent the voltage value of the first end connection position of the first voltage divider circuit 510. The voltage signal at the second sampling point 523 can represent the voltage value of a certain resistor in the second voltage divider circuit 520. The difference between the voltage signal at the first sampling point 513 and the voltage signal at the second sampling point 523 is obtained as the voltage change signal output by the operational amplifier module 530.

[0054] Since the voltage signals at the first sampling point 513 and the second sampling point 523 are generated by the same connected AC power supply 1, if the two voltage change signals have the same interference signal, the same interference signal in the two voltage signals will be removed when the difference is calculated, thereby making the voltage change signal output by the operational amplifier module 530 sufficiently accurate.

[0055] See also Figure 2 , Figure 2 A circuit diagram of a first voltage divider circuit and a second voltage divider circuit according to an embodiment of the present application is shown. In some embodiments of the present application, the first voltage divider circuit 510 may include: a first resistance unit 511, a second resistance unit 512. The second voltage divider circuit 520 may include: a third resistance unit 521, a fourth resistance unit 522. It should be clear that the resistance unit may refer to a single resistance. The resistance unit may also refer to a plurality of resistances connected in series.

[0056] The first end of the first resistor unit 511 can be connected to the first end of the first voltage divider circuit 510. The first end of the second resistor unit 512 can be connected to the second end of the first resistor unit 511. The second end of the second resistor unit 512 can be grounded. The first sampling point 513 is set between the first resistor unit 511 and the second resistor unit 512.

[0057] The first end of the third resistor unit 521 can be connected to the first end of the second voltage divider circuit 520. The first end of the fourth resistor unit 522 can be connected to the second end of the third resistor unit 521. The second end of the fourth resistor unit 522 can be grounded. The second sampling point 523 is set between the third resistor unit 521 and the fourth resistor unit 522.

[0058] In one embodiment of the present application, the resistance values ​​of the first resistance unit 511 and the second resistance unit 512 may be the same or different, and no limitation is made here. The resistance values ​​of the third resistance unit 521 and the fourth resistance unit 522 may be the same or different, and no limitation is made here. That is, the resistance values ​​of the first resistance unit 511, the second resistance unit 512, the third resistance unit 521, and the fourth resistance unit 522 are not limited in any way.

[0059] In the embodiment of the present application, multiple groups of resistor units are provided to share the voltage to reduce the voltage connected to the first sampling point 513 in the first voltage divider circuit 510 and the second sampling point 523 in the second voltage divider circuit 520, thereby reducing the current output at the first sampling point 513 and the second sampling point 523 to prevent damage to the operational amplifier module 530.

[0060] See also Figure 3 , Figure 3 A circuit diagram of an operational amplifier module according to an embodiment of the present application is shown. In some embodiments of the present application, the operational amplifier module 530 may include: a fifth resistor unit 531, a sixth resistor unit 532, an operational amplifier 537, and a first external power supply 538 for supplying power to the operational amplifier.

[0061] The first end of the fifth resistor unit 531 may be connected to the first sampling point 513. The second end of the fifth resistor unit 531 may be connected to the positive input terminal of the operational amplifier 537. The first end of the sixth resistor unit 532 may be connected to the second sampling point 523. The second end of the sixth resistor unit may be connected to the negative input terminal of the operational amplifier 537. The first external power supply 538 may be connected to the operational amplifier 537 to supply power to the operational amplifier 537.

[0062] In the embodiment of the present application, since the current flowing through the first voltage divider circuit 510 and the second voltage divider circuit 520 is too small, the voltage signal difference between the first sampling point 513 and the second sampling point 523 will also be very small, so the first sampling point 513 and the second sampling point 523 are connected to the two input terminals of the operational amplifier 537 via the fifth resistor unit 531 and the sixth resistor unit 532 respectively, and the voltage difference between the first sampling point 513 and the second sampling point 523 is automatically calculated and amplified via the operational amplifier 537. The above circuit greatly improves the automatic effect of the above circuit in obtaining the voltage change signal.

[0063] The fifth resistor unit 531 and the sixth resistor unit 532 are balancing resistors of the operational amplifier 537, which are used to balance the voltages at the positive input terminal and the negative input terminal of the operational amplifier 537, otherwise the operational amplifier cannot operate normally. In the embodiment of the present application, the fifth resistor unit 531, the sixth resistor unit 532 and the operational amplifier 537 can form a differential operational amplifier, which can convert the voltage difference between the positive input terminal and the negative input terminal of the operational amplifier 537 into the voltage difference at the output terminal (that is, as a voltage change signal), thereby achieving the balance of the input terminal voltage and obtaining the voltage change signal of the AC power supply 1.

[0064] It should be noted that, in the embodiment of the present application, the resistance values ​​of the second resistor unit 512 and the fourth resistor unit 522 may be the same or different, and no limitation is made here. The resistance values ​​of the fifth resistor unit 531 and the sixth resistor unit 532 may be the same or different, and no limitation is made here. In one embodiment of the present application, the resistance values ​​of the second resistor unit 512 and the fourth resistor unit 522 are the same. The resistance values ​​of the fifth resistor unit 531 and the sixth resistor unit 532 are the same.

[0065] See also Figure 4 , Figure 4 FIG. 1 shows a circuit diagram of a circuit having a voltage stabilizing function in an operational amplifier module according to an embodiment of the present application. Figure 4 As shown in , the operational amplifier module 530 may further include: a seventh resistance unit 533 and a first capacitor 535 .

[0066] The first end of the seventh resistance unit 533 may be connected to the negative input terminal of the operational amplifier 537. The second end of the seventh resistance unit 533 may be connected to the output terminal of the operational amplifier 537. The first end of the first capacitor 535 may be connected to the negative input terminal of the operational amplifier 537. The second end of the first capacitor 535 may be connected to the output terminal of the operational amplifier 537.

[0067] The first capacitor 535 and the seventh resistor unit 533 are connected in parallel at the input end of the operational amplifier. The frequency response can be improved. The first capacitor 535 can play a filtering role in the above circuit to prevent high-frequency signals from passing. In one embodiment of the present application, when the frequency response needs to be improved, the first capacitor 535 can be connected in parallel to attenuate the low-frequency signal so that the gain in the above circuit mainly acts on the high-frequency signal.

[0068] The first capacitor 535 connected in parallel can also improve the stability of the circuit in the embodiment of the present application. The first capacitor 535 connected in parallel in the above circuit can play a role in stabilizing the above circuit. In particular, when there is negative feedback in the above circuit, the negative feedback will cause the gain of the operational amplifier 537 to decrease, the frequency response to deteriorate, and the phase delay to increase. The first capacitor 535 connected in parallel can form a feedback network at a specific frequency according to the gain characteristics of the operational amplifier 537, improve the phase margin, and stabilize the operation of the above circuit.

[0069] The first capacitor 535 and the seventh resistor unit 533 are connected in parallel to reduce noise: the seventh resistor unit 533 and the first capacitor 535 in the above circuit can play a role in noise reduction. By properly selecting the values ​​of the first capacitor 535 and the seventh resistor unit 533, a low-pass filter can be formed in the above circuit to filter out high-frequency noise.

[0070] The first capacitor 535 and the seventh resistor unit 533 connected in parallel can also prevent electromagnetic interference, and the seventh resistor unit 533 and the first capacitor 535 connected in parallel can also play a role in suppressing electromagnetic interference. Electromagnetic interference refers to the negative impact of the external electromagnetic field on the performance of the circuit. If affected by electromagnetic interference, the voltage change signal output by the operational amplifier 537 will be inaccurate. The function of the first capacitor 535 is to store energy. The first capacitor 535 has a charge when working, which can isolate and absorb electromagnetic waves and hinder the propagation of interference signals. The function of the seventh resistor unit 533 is to limit the flow of current. By selecting an appropriate resistance value, the voltage waveform can be changed, thereby playing an anti-interference role.

[0071] See also Figure 5 , Figure 5 FIG. 1 shows a circuit diagram of a circuit for ensuring positive feedback of an operational amplifier according to an embodiment of the present application. Figure 5The operational amplifier module 530 shown may include: an eighth resistance unit 534 a , a ninth resistance unit 534 b , a second capacitor 536 , and an auxiliary power supply 539 .

[0072] The first end of the eighth resistance unit 534a can be connected to the auxiliary power supply 539. The second end of the eighth resistance unit 534a can be respectively connected to the second end of the ninth resistance unit 534b, the second end of the second capacitor 536, and the positive input end of the operational amplifier 537. The second end of the ninth resistance unit 534b and the second end of the second capacitor 536 are both grounded.

[0073] In the embodiment of the present application, the circuit described in the above embodiment is connected to the positive input terminal of the operational amplifier 537, so that the operational amplifier can always perform positive feedback, avoiding the occurrence of negative feedback. Because if positive feedback and negative feedback occur at the same time, the negative feedback will cause the gain of the operational amplifier 537 to decrease, the frequency response to deteriorate, and the phase delay to increase.

[0074] See also Figure 6 , Figure 6 A circuit diagram of a differential mode interference circuit according to an implementation of the present application is shown. In some embodiments of the present application, the filter circuit 2 may include a differential mode interference circuit 210. A first end of the differential mode interference circuit 210 may be connected to a first end of an AC power source 1. A second end of the differential mode interference circuit 210 may be connected to a second end of the AC power source 1.

[0075] The differential mode interference signal is a form of electromagnetic interference, which mainly occurs between the two wires of the AC power supply 1. The differential mode interference signal is transmitted through these two wires and is a symmetrical interference. The two wires of the AC power supply 1, such as the neutral wire and the live wire, have the same intensity but different directions.

[0076] The voltage sampling circuit described in the first embodiment of this article is a differential sampling circuit. Under ideal conditions, the differential sampling circuit can effectively offset the common-mode interference signal, thereby achieving better signal transmission quality. However, when the differential sampling circuit is subject to external interference, a differential-mode interference signal will be introduced. This interference signal has the same polarity and amplitude as the voltage signal collected by the differential sampling circuit, that is, they cannot be correctly identified and offset by the differential sampling circuit, thereby affecting the accuracy of the voltage change signal. The present application uses a differential-mode interference circuit to remove the differential-mode interference signal generated in the circuit, so that the voltage change signal output by the operational amplifier 537 is more accurate.

[0077] See also Figure 7 , Figure 7A circuit diagram of a common mode interference circuit according to an implementation of the present application is shown. In some embodiments of the present application, the filter circuit 2 may include a common mode interference circuit 220. A first input terminal of the common mode interference circuit 220 may be connected to a first terminal of an AC power source 1. A second input terminal of the common mode interference circuit 220 may be connected to a second terminal of the AC power source 1. A first output terminal of the common mode interference circuit 220 may be connected to a first input terminal of a rectifier circuit 3. A second output terminal of the common mode interference circuit 220 may be connected to a second input terminal of the rectifier circuit 3.

[0078] In one embodiment of the present application, the common mode interference circuit 220 may include: a first inductor 221 and a second inductor 222. The first inductor 221 and the second inductor 222 may be arranged in parallel. The first inductor 221 and the second inductor 222 are arranged in parallel so that the first inductor 221 and the second inductor 222 can generate mutual induction to eliminate the common mode interference in the circuit. The first end of the first inductor 221 may be connected to the first input end of the common mode interference circuit 220.

[0079] The second end of the first inductor 221 may be connected to the first output end of the common mode interference circuit 220 .

[0080] A first end of the second inductor 222 may be connected to a second input end of the common mode interference circuit 220 .

[0081] The second end of the second inductor 222 may be connected to the second output end of the common mode interference circuit 220 .

[0082] Common-mode interference refers to interference voltage signals with the same amplitude and direction on two conductors. By collecting voltage change signals through a differential sampling circuit, a portion of the common-mode interference signal can be eliminated, and then the common-mode interference signal in the circuit can be removed through the common-mode interference circuit 220. Under the double removal effect, the common-mode interference signal in the circuit can be removed to the greatest extent.

[0083] See also Figure 8 , Figure 8 A circuit diagram of a differential mode interference circuit and a common mode interference circuit according to an implementation of the present application is shown. In some embodiments of the present application, the filter circuit 2 may include: a third capacitor 211 and a fourth capacitor 212. The third capacitor 211 and the fourth capacitor 212 may form a differential mode interference circuit according to the following connection relationship.

[0084] The first end of the third capacitor 211 may be connected between the first end of the AC power supply 1 and the first input end of the common mode interference circuit 220. The second end of the third capacitor 211 may be connected between the second end of the AC power supply 1 and the second input end of the common mode interference circuit 220. The first end of the fourth capacitor 212 may be connected between the first output end of the common mode interference circuit 220 and the first end of the sampling circuit 5. The second end of the fourth capacitor 212 may be connected between the second output end of the common mode interference circuit 220 and the second end of the sampling circuit 5.

[0085] In another embodiment of the present application, the first end of the third capacitor 211 can be connected between the first end of the AC power source 1 and the first end of the first inductor 221. The second end of the third capacitor 211 can be connected between the second end of the AC power source 1 and the first end of the second inductor 222. The first end of the fourth capacitor 212 can be connected between the second end of the first inductor 221 and the first end of the sampling circuit 5. The second end of the fourth capacitor 212 can be connected between the second end of the second inductor 222 and the second end of the sampling circuit 5.

[0086] In the embodiment of the present application, not only is a differential mode interference circuit provided to eliminate differential mode interference signals, but also a third capacitor and a fourth capacitor are provided to eliminate common mode interference signals in the voltage sampling circuit, so that the collected voltage change signal is more accurate.

[0087] In some embodiments of the present application, the voltage sampling circuit further includes a power factor compensation circuit for adjusting the voltage and / or current output by the rectifier circuit 3 according to the voltage change signal acquired by the sampling circuit 5 .

[0088] The first end of the power factor compensation circuit can be connected between the first output end of the rectifier circuit 3 and the first end of the load circuit 4. The second end of the power factor compensation circuit can be connected between the second output end of the rectifier circuit 3 and the second end of the load circuit 4.

[0089] In the embodiment of the present application, based on the collected accurate voltage change signal, the power factor compensation circuit can output voltage and / or current more accurately, thereby synchronizing the current change and voltage change in the load circuit 4, reducing the useless power in the load circuit 4 and increasing the useful power. Finally, the load circuit 4 makes more efficient use of electrical energy.

[0090] In some embodiments of the present application, any of the above circuits can be provided in a household appliance having a variable frequency motor. The variable frequency motor is contained in the load circuit 4, and the voltage change signal output by the voltage sampling circuit is used for pulse width modulation to control the variable frequency motor. The useless power generated by the variable frequency motor during operation is reduced, thereby increasing the useful power of the variable frequency motor, making the application of electric energy by the household appliance more efficient, and increasing the energy-saving experience of the household appliance for the user.

[0091] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0092] It should be understood that the above content is only a preferred exemplary embodiment of the present application and is not intended to limit the implementation scheme of the present application. A person skilled in the art can easily make corresponding changes or modifications based on the main concept and spirit of the present application. Therefore, the scope of protection of the present application shall be based on the scope of protection required by the claims.

Claims

1. A voltage sampling circuit, characterized in that: The circuit comprises: A filter circuit, the filter circuit is connected to an AC power supply and is used to filter the AC power supply; A rectifier circuit, wherein a first input end of the rectifier circuit is connected to a first output end of the filter circuit, a second input end of the rectifier circuit is connected to a second output end of the filter circuit, and the rectifier circuit is used to convert the alternating current output by the filter circuit into direct current; A load circuit connected to an output end of the filter circuit; A sampling circuit, wherein the first end of the sampling circuit is connected between the first output end of the filter circuit and the first input end of the rectifier circuit, and the second end of the sampling circuit is connected between the second output end of the filter circuit and the second input end of the rectifier circuit, and the sampling circuit is used to collect and output a voltage change signal; wherein, The sampling circuit includes a first voltage divider circuit, a second voltage divider circuit, and an operational amplifier module; A plurality of resistors are respectively provided in the first voltage divider circuit and the second voltage divider circuit, a first end of the first voltage divider circuit serves as a first end of the sampling circuit, a second end of the second voltage divider circuit serves as a second end of the sampling circuit, and the second end of the first voltage divider circuit and the second end of the second voltage divider circuit are grounded; A first sampling point in the first voltage divider circuit is connected to a first input terminal of the operational amplifier module, a second sampling point in the second voltage divider circuit is connected to a second input terminal of the operational amplifier module, the first sampling point is arranged between any two resistors in the first voltage divider circuit, and the second sampling point is arranged between any two resistors in the second voltage divider circuit.

2. The circuit according to claim 1, characterized in that The first voltage divider circuit includes: a first resistance unit and a second resistance unit; the second voltage divider circuit includes a third resistance unit and a fourth resistance unit; wherein, A first end of the first resistance unit is connected to a first end of the first voltage divider circuit, and a second end of the first resistance unit is connected to a first end of the second resistance unit; The second end of the second resistance unit is grounded; The first end of the third resistor unit is connected to the first end of the second voltage divider circuit, and the second end of the third resistor unit is connected to the first end of the fourth resistor unit; A second terminal of the fourth resistance unit is grounded.

3. The circuit according to claim 1, characterized in that The operational amplifier module includes: a fifth resistor unit, a sixth resistor unit, and an operational amplifier; wherein, A first end of the fifth resistor unit is connected to the first sampling point, and a second end of the fifth resistor unit is connected to a positive input end of the operational amplifier; A first end of the sixth resistance unit is connected to the second sampling point, and a second end of the sixth resistance unit is connected to the negative input end of the operational amplifier.

4. The circuit according to claim 3, characterized in that The operational amplifier module also includes: a seventh resistance unit, wherein a first end of the seventh resistance unit is connected to the negative input end of the operational amplifier, and a second end of the seventh resistance unit is connected to the output end of the operational amplifier; A first capacitor, wherein a first end of the first capacitor is connected to the negative input end of the operational amplifier, and a second end of the first capacitor is connected to the output end of the operational amplifier.

5. The circuit according to claim 3, characterized in that The operational amplifier module also includes: an eighth resistance unit, wherein a first end of the eighth resistance unit is connected to the auxiliary power supply, and a second end of the eighth resistance unit is respectively connected to a first end of the ninth resistance unit, a first end of the second capacitor, and a positive input end of the operational amplifier; The second ends of the ninth resistance unit and the second capacitor are grounded.

6. The circuit according to claim 1, characterized in that The filtering circuit comprises: A differential mode interference circuit, wherein a first end of the differential mode interference circuit is connected to a first end of the AC power supply, and a second end of the differential mode interference circuit is connected to a second end of the AC power supply.

7. The circuit according to claim 1, characterized in that The filtering circuit comprises: A common mode interference circuit, wherein a first input end of the common mode interference circuit is connected to a first end of the AC power supply, a second input end of the common mode interference circuit is connected to a second end of the AC power supply, a first output end of the common mode interference circuit is connected to a first input end of the rectifier circuit, and a second output end of the common mode interference circuit is connected to a second input end of the rectifier circuit.

8. The circuit according to claim 7, characterized in that The filter circuit also includes: a third capacitor, wherein a first end of the third capacitor is connected between the first end of the AC power supply and the first input end of the common-mode interference circuit, and a second end of the third capacitor is connected between the second end of the AC power supply and the second input end of the common-mode interference circuit; A fourth capacitor, wherein a first end of the fourth capacitor is connected between the first output end of the common-mode interference circuit and the first end of the sampling circuit, and a second end of the fourth capacitor is connected between the second output end of the common-mode interference circuit and the second end of the sampling circuit.

9. The circuit according to claim 1, characterized in that The circuit further comprises: A power factor compensation circuit is used to adjust the voltage and / or current output by the rectifier circuit according to the voltage change signal obtained by the sampling circuit, wherein the first end of the power factor compensation circuit is connected between the first output end of the rectifier circuit and the first end of the load circuit, and the second end of the power factor compensation circuit is connected between the second output end of the rectifier circuit and the second end of the load circuit.

10. A household appliance, characterized in that: include: Variable frequency motor; as well as According to the voltage sampling circuit as described in any one of claims 1 to 9, the variable frequency motor is included in the load circuit, and the voltage change signal output by the voltage sampling circuit is used for pulse width modulation to control the variable frequency motor.

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