A power detection circuit, method and electric device

Abstract

The present invention discloses a power detection circuit, method and electric equipment. The power detection circuit includes: a first sampling module, which is arranged on the positive bus or negative bus of the power supply system, and is used to obtain a first sampling voltage; a second sampling module, which is arranged between the positive bus and the negative bus of the power supply system, and is used to divide the actual voltage input by the electric equipment to obtain a second sampling voltage; a power calculation module, whose input ends are respectively connected to the first sampling module and the second sampling module, and is used to calculate the actual current according to the first sampling voltage, obtain the actual voltage according to the second sampling voltage, and calculate the power of the electric equipment according to the actual current, the actual voltage and the power factor. Through the present invention, power detection can be performed without setting a sampling bias circuit, a differential operation circuit and a current sensor, which simplifies the circuit structure and reduces the cost.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to a power detection circuit, method and electrical equipment. Background Art

[0002] The power calculation accuracy of electricity metering is required to be controlled within 5% for household billing of electrical equipment or for shared electrical equipment. Figure 1 For conventional power detection circuits, such as Figure 1 As shown, the conventional power detection circuit uses the AC side of the power input to sample the voltage and current of the input power to calculate the input power P = U*I*power factor. The sampling circuit in this circuit also requires a 1.65V sampling bias circuit, a differential operation circuit and a current sensor. The circuit structure is complex and has many components, resulting in a high power detection cost.

[0003] With regard to the problem that the power detection circuit in the prior art has a complex structure and thus leads to high costs, no effective solution has been proposed yet. Summary of the invention

[0004] The embodiments of the present invention provide a power detection circuit, method and electric device to solve the problem that the power detection circuit in the prior art has a complex structure and thus leads to a high cost.

[0005] In order to solve the above technical problems, the present invention provides a power detection circuit, which includes:

[0006] A first sampling module is provided on a positive bus or a negative bus of a power supply system, and is used to obtain a first sampling voltage;

[0007] A second sampling module is provided between the positive bus and the negative bus of the power supply system, and is used to obtain a second sampling voltage after dividing the actual voltage input by the electrical equipment;

[0008] A power calculation module, whose input ends are respectively connected to the first sampling module and the second sampling module, is used to calculate the actual current according to the first sampling voltage, obtain the actual voltage according to the second sampling voltage, and calculate the power of the electrical equipment according to the actual current, the actual voltage and the power factor.

[0009] Furthermore, the power calculation module is also used to calculate the sum of the thermal power of the rectifier bridge in the power supply system and the power of the electrical equipment to obtain the total power.

[0010] Furthermore, the first sampling module includes:

[0011] A sampling resistor is arranged on the positive bus or the negative bus of the power supply system;

[0012] A first voltage dividing unit, a first end of which is connected to the first end of the sampling resistor, a second end of which is connected to the first voltage source, and an output end of which is connected to the non-inverting input end of the operational amplifier;

[0013] The operational amplifier, whose inverting input terminal is connected to the second end of the sampling resistor through a first resistor, and whose output terminal is connected to the power calculation module, is used to output the first sampling voltage; wherein the first sampling voltage is equal to the voltage difference between the two ends of the sampling resistor;

[0014] The output terminal of the operational amplifier is also connected to the inverting input terminal of the operational amplifier itself through a second resistor.

[0015] Furthermore, the first voltage dividing unit includes:

[0016] A third resistor and a fourth resistor are arranged in series, the third resistor is connected to the first end of the sampling resistor, the fourth resistor is connected to the first voltage source, and a wire is led out between the third resistor and the fourth resistor, serving as the output end of the first voltage divider unit, and connected to the non-inverting input end of the operational amplifier.

[0017] Furthermore, the first voltage dividing unit further includes:

[0018] The first capacitor is arranged in parallel at both ends of the fourth resistor, and is used to limit the magnitude of the voltage output by the first voltage dividing unit.

[0019] Furthermore, the first sampling module further includes:

[0020] a fifth resistor, a first end of which is connected to the output end of the operational amplifier;

[0021] a second capacitor, a first end of which is connected to the second end of the fifth resistor, and a second end of which is connected to the negative bus of the power supply system;

[0022] The fifth resistor and the second capacitor are used to filter the first sampling voltage and output it through a wire between the fifth resistor and the second capacitor.

[0023] Furthermore, the second sampling module includes:

[0024] A second voltage dividing unit, having a first end connected to the positive bus of the power supply system, a second end connected to the negative bus of the power supply system, and an output end connected to the power calculation module, is used to output the second sampling voltage.

[0025] Furthermore, the second voltage dividing unit includes:

[0026] A sixth resistor and a seventh resistor are arranged in series, the sixth resistor is connected to the positive bus of the power supply system, the seventh resistor is connected to the negative bus of the power supply system, and a wire is led out between the sixth resistor and the seventh resistor as the output end of the second voltage divider unit.

[0027] Furthermore, the second sampling module further includes:

[0028] A first voltage stabilizing unit and a second voltage stabilizing unit are connected in series in the same direction, the first voltage stabilizing unit is connected to a second voltage source, the second voltage stabilizing unit is connected to a negative bus of the power supply system, a wire is led out between the first voltage stabilizing unit and the second voltage stabilizing unit, and connected to the output end of the second voltage dividing unit, the first voltage stabilizing unit and the second voltage stabilizing unit are used to control the output voltage of the second voltage dividing unit.

[0029] Furthermore, the second sampling module further includes:

[0030] An eighth resistor, a first end of which is the output end of the operational amplifier;

[0031] a third capacitor, a first end of which is connected to the second end of the eighth resistor, and a second end of which is connected to the negative busbar of the power supply system;

[0032] The eighth resistor and the third capacitor are used to filter the second sampling voltage and output it through a wire between the eighth resistor and the third capacitor.

[0033] Furthermore, the power detection circuit also includes a power factor correction circuit, and the power factor correction circuit includes:

[0034] an inductor and a boost diode, wherein the inductor and the diode are connected in series and connected between a connection point between the second sampling module and the positive bus of the power supply system and a positive bus terminal of the power supply system;

[0035] A switch tube, a first end of which is connected between the inductor and the boost diode, and a second end of which is connected to the negative bus of the power supply system.

[0036] The present invention also provides an electrical device, comprising the power detection circuit.

[0037] Furthermore, the electrical equipment includes at least one of the following:

[0038] Air conditioners, washing machines, refrigerators, water heaters, fans, dryers, air purifiers, water purifiers, and water purifiers.

[0039] The present invention also provides a power detection method, which is applied to the above power detection circuit, and the method comprises:

[0040] Calculate the actual current according to the first sampled voltage, and calculate the actual voltage according to the second sampled voltage;

[0041] The power factor is acquired according to the operating state of the power supply system, and the power of the electrical equipment is calculated according to the power factor, the actual current and the actual voltage.

[0042] Further, calculating the actual current according to the first sampled voltage includes:

[0043] Calculating a sampling current according to the first sampling voltage, wherein the sampling current=the first sampling voltage / the resistance value of the sampling resistor;

[0044] Amplifying the sampled current according to a first preset ratio to obtain an actual current;

[0045] Calculating the actual voltage according to the second sampled voltage includes:

[0046] The second sampled voltage is amplified by a second preset ratio to obtain an actual voltage.

[0047] Furthermore, obtaining a power factor according to the operating state of the power supply system, and calculating the power of the electrical equipment according to the power factor, the actual current, and the actual voltage, includes:

[0048] Determine whether the power factor correction circuit is enabled;

[0049] If yes, the power factor is calculated according to the first sampled voltage and the second sampled voltage, and the number of power calculations is determined according to the power supply frequency; the sum of the power calculation results is calculated according to the power factor and the number of power calculations to obtain the power of the electrical equipment;

[0050] If not, a preset power factor is obtained, and the product of the preset power factor, the actual voltage and the actual current is calculated to obtain the power of the electrical equipment.

[0051] Further, calculating the power factor according to the first sampled voltage and the second sampled voltage includes:

[0052] Determining a time instant of capturing the first sampling voltage according to a first voltage threshold and a first phase angle;

[0053] Determining a time instant for capturing the second sampling voltage according to a second voltage threshold and a second voltage phase angle;

[0054] Obtaining a time difference between a time instant of intercepting the first sampling voltage and a time instant of intercepting the second sampling voltage;

[0055] Acquire a phase difference between the second sampled voltage and the first sampled voltage according to the time difference, and calculate a cosine value of the phase difference;

[0056] Performing Fourier expansion on the first sampled voltage to calculate the sum of each harmonic content;

[0057] The power factor is obtained by calculating the product of the cosine value of the phase difference and the sum of the harmonic contents.

[0058] Further, the number of power calculations is determined according to the power supply frequency, including:

[0059] determining a first frequency and a second frequency of a power system;

[0060] A common multiple of the first frequency and the second frequency is calculated as the number of power calculations.

[0061] Furthermore, after obtaining the power factor according to the operating state of the power supply system and calculating the power of the electrical equipment according to the power factor, the actual current and the actual voltage, the method further includes:

[0062] Calculate the thermal power of the rectifier bridge in the power supply system;

[0063] The sum of the thermal power of the rectifier bridge and the electrical equipment is calculated to obtain the total power.

[0064] Furthermore, the thermal power of the rectifier bridge in the power supply system is calculated based on the following formula:

[0065] P1=r(t)×I 2 ;

[0066] Wherein, P1 is the thermal power of the rectifier bridge, r(t) is the function of the change of the resistance of the rectifier bridge over time, and I is the actual current.

[0067] Furthermore, after obtaining the total power, the method further includes:

[0068] The power consumption of the power-consuming device is calculated according to the total power and the power consumption time.

[0069] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the power detection method is implemented.

[0070] By applying the technical solution of the present invention, a first sampling module is set to obtain a first sampling voltage, a second sampling module is set to obtain a second sampling voltage, an actual current is calculated according to the first sampling voltage through a power calculation module, an actual voltage is calculated according to the second sampling voltage, and a power factor is calculated. There is no need for a sampling bias circuit, a differential operation circuit and a current sensor, which simplifies the circuit structure and reduces the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 It is a conventional power detection circuit;

[0072] Figure 2 is a structural diagram of a power supply system and a power detection circuit according to an embodiment of the present invention;

[0073] Figure 3 is a structural diagram of a power supply system and a power detection circuit according to another embodiment of the present invention;

[0074] Figure 4 is a flow chart of a power detection method according to an embodiment of the present invention;

[0075] Figure 5 A calculation flow chart of a power factor according to an embodiment of the present invention;

[0076] Figure 6 FIG. 4 is a flow chart of a power detection method according to another embodiment of the present invention. DETAILED DESCRIPTION

[0077] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0078] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0079] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0080] It should be understood that, although the terms first, second, etc. may be used to describe the sampled voltages in the embodiments of the present invention, the sampled voltages should not be limited to these terms. These terms are only used to distinguish the sampled voltages obtained by different sampling modules. For example, without departing from the scope of the embodiments of the present invention, the first sampled voltage may also be referred to as the second sampled voltage, and similarly, the second sampled voltage may also be referred to as the first sampled voltage.

[0081] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0082] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0083] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0084] Example 1

[0085] This embodiment provides a power detection circuit, which is applied to a power supply system. Figure 2 is a structural diagram of a power supply system and a power detection circuit according to an embodiment of the present invention, such as Figure 2As shown, the power supply system includes: a rectifier bridge DB1, which includes at least four diodes. After the four diodes are connected in reverse series in pairs, two rectifier bridge arms are formed respectively. The two bridge arms are arranged in parallel between the live terminal AC-L and the neutral terminal AC-N of the AC power supply. The line drawn between the two reversely connected diodes in the first rectifier bridge arm is the positive bus P of the power supply system, and the line drawn between the two reversely connected diodes in the second rectifier bridge arm is the negative bus GDN_DRIVE of the power supply system. The AC input power supply AC rectifies the sinusoidal current U0 into a "mantou" wave DC power supply DC through the rectifier bridge DB1, and the AC power output by the AC power supply AC is rectified by the diodes in the rectifier bridge DB1 to form a DC power supply voltage with a waveform of a "mantou" wave, that is, the AC voltage amplitude below 0.7V is flipped to above 0.7V, and output to the positive bus P and the negative bus GND_DRIVE as the input power of the power factor correction circuit PFC to supply power to the electrical equipment side of the inverter circuit.

[0086] The power detection circuit includes: a first sampling module 10, which is arranged on the positive bus or the negative bus of the power supply system, and is used to obtain a first sampling voltage; a second sampling module 20, which is arranged between the positive bus P and the negative bus GDN_DRIVE of the power supply system, and is used to divide the actual voltage input by the power-consuming device to obtain a second sampling voltage;

[0087] The power calculation module 30, whose input ends are respectively connected to the first sampling module 10 and the second sampling module 20, is used to calculate the actual current I according to the first sampling voltage U1, obtain the actual voltage U according to the second sampling voltage U2, and calculate the power of the electrical equipment according to the actual current I, the actual voltage U, and the power factor PF.

[0088] The technical solution of this embodiment is to set a first sampling module to obtain a first sampling voltage, set a second sampling module to obtain a second sampling voltage, calculate the actual current according to the first sampling voltage through a power calculation module, calculate the actual voltage according to the second sampling voltage, and calculate the power factor. There is no need for a sampling bias circuit, a differential operation circuit and a current sensor, which simplifies the circuit structure and reduces the cost.

[0089] In other embodiments of the present invention, the power calculation module 30 may also be used to calculate the sum of the thermal power of the rectifier bridge in the power supply system and the power of the electrical equipment to obtain the total power.

[0090] Example 2

[0091] This embodiment provides another power detection circuit. Figure 3FIG. 1 is a structural diagram of a power supply system and a power detection circuit according to another embodiment of the present invention. Since the power calculation module 30 is generally a chip, the maximum voltage allowed to be input is relatively low (generally 3.3V). In order to control the first sampling voltage, as shown in FIG. Figure 3 As shown, the first sampling module 10 includes: a sampling resistor RS1, which is arranged on the positive bus P or the negative bus of the power supply system; a first voltage divider unit 101, whose first end is connected to the first end of the sampling resistor RS1, whose second end is connected to the first voltage source, and whose output end is connected to the in-phase input terminal + of the operational amplifier U16-B; the operational amplifier U16-B, whose inverting input terminal - is connected to the second end of the sampling resistor RS1 through the first resistor R1, and whose output end is connected to the power calculation module 30, for outputting the first sampling voltage U1; wherein the first sampling voltage U1 is equal to the voltage difference across the sampling resistor RS1; the output end of the operational amplifier U16-B is also connected to the inverting input terminal - of the operational amplifier U16-B itself through the second resistor R2.

[0092] The first voltage divider unit 101 includes: a third resistor R3 and a fourth resistor R4 arranged in series, the third resistor R3 is connected to the first end of the sampling resistor RS1, the fourth resistor R4 is connected to the first voltage source, and a wire is led out between the third resistor R3 and the fourth resistor R4, which serves as the output end of the first voltage divider unit and is connected to the in-phase input end + of the operational amplifier U16-B.

[0093] As described above, since the power calculation module 30 is generally a chip, the maximum allowed input voltage is relatively low (generally 3.3V). Therefore, in order to control the first sampling voltage U1, the first voltage divider unit 101 also includes: a first capacitor C1, which is arranged in parallel at both ends of the fourth resistor R4, and is used to limit the magnitude of the voltage output by the first voltage divider unit 101.

[0094] The waveform of the first sampling voltage U1 is not necessarily smooth, and may have sawtooth or spikes. In order to eliminate the sawtooth or spikes in the waveform of the first sampling voltage U1, the first sampling module 10 further includes: a fifth resistor R5, a first end of which is connected to the output end of the operational amplifier U16-B; a second capacitor C2, a first end of which is connected to the second end of the fifth resistor R5, and a second end of which is connected to the negative bus GND_DRIVE of the power supply system;

[0095] The fifth resistor R5 and the second capacitor C2 are used to filter the first sampling voltage U1 and output it through the wire between the fifth resistor R5 and the second capacitor C2.

[0096] Since the actual voltage is relatively large, in order to obtain a smaller second sampling voltage, the second sampling module 20 includes: a second voltage dividing unit 201, a first end of which is connected to the positive bus P of the power supply system, a second end of which is connected to the negative bus GND_DRIVE of the power supply system, and an output end of which is connected to the power calculation module 30, for outputting the second sampling voltage to the power calculation module 30.

[0097] Specifically, the second voltage divider unit 201 includes: a sixth resistor R6 and a seventh resistor R7 arranged in series, the sixth resistor R6 is connected to the positive bus P of the power supply system, the seventh resistor R7 is connected to the negative bus GND_DRIVE of the power supply system, and a wire is led out between the sixth resistor R6 and the seventh resistor R7 as the output end of the second voltage divider unit 201. It should be noted that the sixth resistor R6 and the seventh resistor R7 can be a single resistor, or can be formed by a plurality of small resistors connected in series, which is not specifically limited in the present invention.

[0098] In order to further prevent the value of the second sampling voltage from exceeding the maximum voltage allowed to be input by the power calculation module 30, the second sampling module 20 further includes:

[0099] The first voltage stabilizing unit D1 and the second voltage stabilizing unit D2 are connected in series in the same direction, the first voltage stabilizing unit D1 is connected to the second voltage source, the second voltage stabilizing unit D2 is connected to the negative bus GND_DRIVE of the power supply system, a wire is led out between the first voltage stabilizing unit D1 and the second voltage stabilizing unit D2, and connected to the output end of the second voltage dividing unit 201, the first voltage stabilizing unit D1 and the second voltage stabilizing unit D2 are used to control the output voltage of the second voltage dividing unit 201 so that it does not exceed the maximum voltage allowed to be input by the power calculation module 30, wherein the voltage value provided by the second voltage source can be set to the maximum voltage allowed to be input by the power calculation module 30.

[0100] The waveform of the second sampling voltage U2 is not necessarily smooth, and may have sawtooth or spikes. In order to eliminate the sawtooth or spikes in the waveform of the second sampling voltage U2, the second sampling module 20 further includes: an eighth resistor R6, a first end of which is the output end of the operational amplifier U16-B; a third capacitor, a first end of which is connected to the second end of the eighth resistor R6, and a second end of which is connected to the negative bus GND_DRIVE of the power supply system;

[0101] The eighth resistor R6 and the third capacitor C3 are used to filter the second sampling voltage U2 and then output it through the wire between the eighth resistor R6 and the third capacitor C3.

[0102] In practical applications, due to the phase change between the input current and the input voltage, the power factor may be inaccurate. Therefore, in this embodiment, the power detection circuit also includes a power factor correction circuit PFC, which includes: an inductor L and a boost diode D3. After the inductor L and the boost diode D3 are connected in series, they are connected to the connection point between the second sampling module 20 and the positive bus P of the power supply system, and the positive bus terminal of the power supply system; a switch tube Q, a first end of which is connected between the inductor L and the boost diode D3, and a second end of which is connected to the negative bus GND_DRIVE of the power supply system.

[0103] Example 3

[0104] This embodiment provides a power detection method, which is applied to the above power detection circuit. Figure 4 : is a flow chart of a power detection method according to an embodiment of the present invention. Figure 4 As shown, the method includes:

[0105] S101, calculating an actual current according to a first sampled voltage, and calculating an actual voltage according to a second sampled voltage.

[0106] Since the calculation of power requires obtaining the actual current and the actual voltage, and the first sampling module of the present application obtains the first sampling voltage instead of the current, and the second sampling module obtains the second sampling voltage which is much smaller than the actual voltage, in order to calculate the power, it is necessary to calculate the actual current based on the first sampling voltage and calculate the actual voltage based on the second sampling voltage.

[0107] S102, obtaining a power factor according to the operating status of the power supply system, and calculating the power of the electrical equipment according to the power factor, the actual current, and the actual voltage.

[0108] The operating state of the power supply system includes two states: a power factor correction circuit is enabled and a power factor correction circuit is not enabled. For the above two states, the calculation method of the power factor is different.

[0109] The technical solution of this embodiment first calculates the actual current according to the first sampled voltage and the actual voltage according to the second sampled voltage; then obtains the power factor according to the operating state of the power supply system, and calculates the power of the electrical equipment according to the power factor, the actual current and the actual voltage. In the sampling process, there is no need for sampling bias circuits, differential operation circuits and current sensors, which simplifies the circuit structure and reduces costs.

[0110] Example 4

[0111] This example provides another power detection method. Since the first sampling module directly obtains the voltage across the sampling resistor instead of the current, in order to calculate the power, the actual current is obtained according to the first sampling voltage, including: calculating the sampling current according to the first sampling voltage, wherein the sampling current = the first sampling voltage / the resistance value of the sampling resistor; and since the sampling current is obtained by reducing the actual current according to the first preset ratio, it is also necessary to amplify the sampling current according to the first preset ratio to obtain the actual current. The second sampling voltage is obtained by dividing the actual voltage according to the second preset ratio, therefore, calculating the actual voltage according to the second sampling voltage includes: amplifying the second sampling voltage by the second preset ratio to obtain the actual voltage.

[0112] After obtaining the actual current and the actual voltage, it is also necessary to obtain the power factor according to the operating status of the power supply system, and calculate the power of the electrical equipment based on the power factor, the actual current and the actual voltage, specifically including: judging whether the power factor correction circuit is enabled; if so, calculating the power factor based on the first sampling voltage and the second sampling voltage, and determining the number of power calculations based on the power supply frequency; calculating the sum of the results of each power calculation based on the power factor and the number of power calculations to obtain the power of the electrical equipment; if not, obtaining a preset power factor, calculating the product of the preset power factor and the actual voltage and the actual current to obtain the power of the electrical equipment.

[0113] Figure 5 is a flow chart of calculating the power factor according to an embodiment of the present invention, such as Figure 5 As shown, calculating the power factor according to the first sampling voltage and the second sampling voltage includes:

[0114] Determine the interception time T1 of the first sampling voltage according to the first voltage threshold value |u1| and the first phase angle ∠u1; determine the interception time T2 of the second sampling voltage according to the second voltage threshold value |u2| and the second voltage phase angle ∠u2; obtain the time difference ΔT between the interception time T1 of the first sampling voltage and the interception time T2 of the second sampling voltage; obtain the phase difference θ between the second sampling voltage and the first sampling voltage according to the time difference ΔT, and calculate the cosine value cosθ of the phase difference; perform Fourier expansion on the first sampling voltage U1, calculate each harmonic content value THD, and sum them, the summation formula is: in, is the value of the nth harmonic content; the product of the cosine value cosθ of the phase difference and the sum of the harmonic contents is calculated to obtain the power factor PF.

[0115] In order to ensure that the method is applicable regardless of whether the power frequency is the first frequency or the second frequency, the power calculation times are determined according to the power frequency, including: determining the first frequency and the second frequency of the power system; calculating the common multiple of the first frequency and the second frequency as the power calculation times. For example, the power frequency can be 50Hz or 60Hz, then the common multiple of 50 and 60 is determined, preferably the least common multiple of 300 is used as the power calculation times, and the power of the electrical equipment is calculated. Wherein, n represents the number of calculations. In this embodiment, the time interval between two calculations is 200 us.

[0116] Since the power supply system also includes a rectifier bridge, in order to ensure the accuracy of the power calculation value, the power factor is obtained according to the operating status of the power supply system, and the power of the electrical equipment is calculated according to the power factor, actual current, and actual voltage. The above method also includes: calculating the thermal power of the rectifier bridge in the power supply system; calculating the sum of the thermal power of the rectifier bridge and the electrical equipment to obtain the total power. The formula for calculating the thermal power of the rectifier bridge in the power supply system is: P1 = r(t) × I 2 ; Wherein, P1 is the thermal power of the rectifier bridge, r(t) is the function of the resistance of the rectifier bridge changing with time, and I is the actual current. After obtaining the total power, the power consumption of the electrical equipment can also be calculated based on the total power and power consumption time.

[0117] Example 5

[0118] This embodiment provides a power detection circuit, which is applied to a power supply system, as mentioned above. Figure 3 As shown in , the power supply system includes: a rectifier bridge DB1, which includes at least four diodes. After the four diodes are connected in reverse series in pairs, two rectifier bridge arms are formed respectively. The two bridge arms are arranged in parallel between the live terminal AC-L and the neutral terminal AC-N of the AC power supply. The line drawn between the two reversely connected diodes in the first rectifier bridge arm is the positive bus P of the power supply system, and the line drawn between the two reversely connected diodes in the second rectifier bridge arm is the negative bus GDN_DRIVE of the power supply system. The AC input power supply AC rectifies the sinusoidal current U0 into a "mantou" wave DC power supply DC through the rectifier bridge DB1, and the AC power output by the AC power supply AC is rectified by the diodes in the rectifier bridge DB1 to form a DC power supply voltage with a waveform of a "mantou" wave, that is, the AC voltage amplitude below 0.7V is flipped to above 0.7V, and output to the positive bus P and the negative bus GND_DRIVE as the input power of the power factor correction circuit PFC to supply power to the electrical equipment side of the inverter circuit.

[0119] like Figure 3As shown, the power detection circuit includes a first sampling module 10, which collects a first voltage from the negative bus GND_DRIVE to obtain an actual current I. The first sampling module 10 includes a sampling resistor RS1, which is connected in series to the negative bus GND_DRIVE, and also includes a first resistor R1R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and an operational amplifier U16-B, wherein a first end of the third resistor R3 is connected to a first end of the sampling resistor RS1, a second end is connected to a fourth resistor R4, and the other end of the fourth resistor R4 is connected to a first voltage source, a wire between the third resistor R3 and the fourth resistor R4 is connected to a non-inverting input terminal + of the operational amplifier U16-B, an inverting input terminal - of the operational amplifier U16-B is connected to a second end of the sampling resistor RS1 through the first resistor R1, an output terminal is connected to a power calculation module 30, and is also connected to its own inverting input terminal - through the second resistor R2, and a first sampling voltage U1 output by the operational amplifier U16-B is output to the power calculation module 30 after low-pass filtering by the fifth resistor R5 and the first capacitor C1. The 1.65V sampling bias circuit, differential operation circuit and current sensor of the conventional circuit are omitted.

[0120] like Figure 3 As shown, the power detection module also includes a second sampling module 20, and the second sampling module 20 includes a sixth resistor R6 and a seventh resistor R7. After the sixth resistor R6 and the seventh resistor R7 are connected in series, one end is connected to the positive bus P, and the other end is connected to the negative bus GND_DRIVE. The sixth resistor R6 and the seventh resistor R7 output the second sampling voltage U2, which is low-pass filtered by the eighth resistor R8 and the third capacitor C3 and then output to the power calculation module 30. It should be noted that the sixth resistor R6 and the seventh resistor R7 can be a single resistor, or can be formed by a plurality of small resistors in series, which is not specifically limited in the present invention.

[0121] In order to ensure that the second sampling voltage U2 does not exceed the maximum allowable input voltage (for example, 3.3V) of the power calculation module 30, a first voltage stabilizing unit D1 and a second voltage stabilizing unit D2 are connected in series in the same direction, the first voltage stabilizing unit D1 is connected to a second voltage source (so that the voltage provided by the second voltage source is equal to the maximum allowable input voltage of the power calculation module 30), the second voltage stabilizing unit D2 is connected to the negative bus GND_DRIVE, a wire is led out between the first voltage stabilizing unit D1 and the second voltage stabilizing unit D2, and connected between the sixth resistor R6 and the seventh resistor R7, the first voltage stabilizing unit D1 and the second voltage stabilizing unit D2 are used to control the size of the second sampling voltage not to exceed the maximum allowable input voltage of the power calculation module 30 through clamping.

[0122] The power detection circuit of this embodiment adopts sampling of the DC side voltage and current of the input power supply, which can realize the lean design requirements of simple circuit, few components, low cost and high reliability.

[0123] This embodiment also provides another power detection method: Figure 6 FIG. 4 is a flow chart of a power detection method according to another embodiment of the present invention. Figure 6 As shown, the method includes:

[0124] S1, converting the actual current I and the actual voltage U according to the first sampling voltage U1 and the second sampling voltage U2.

[0125] For example: the sampled current I1=actual current I*first sampling coefficient K1, then the actual current I=sampled current I1 / first sampling coefficient K1; the sampled current I1=first sampling voltage U1 / resistance of the sampling resistor RS1, wherein K1 is determined by the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3 and the third resistor R4, and can be set to 0.06; the second sampled voltage U2=actual voltage U*second sampling coefficient K2, then the actual voltage U=second sampled voltage U2 / second sampling coefficient K2, wherein K2 is determined by the resistances of the sixth resistor R6 and the seventh resistor R7, and K2 can be equal to 0.0055. In a specific implementation, it is necessary to ensure that the first sampled voltage U1 and the second sampled voltage are less than 3.3V.

[0126] S2, calculate the thermal power of the rectifier bridge in the power supply system.

[0127] In this embodiment, due to the presence of a rectifier bridge, input power calculation compensation is required to calculate the thermal power of the rectifier bridge in the power supply system, and the formula based on which is: P1 = r(t) × I 2 ; Wherein, P1 is the thermal power of the rectifier bridge, r(t) is the function of the change of the resistance of the rectifier bridge over time, and I is the actual current.

[0128] S3, determine whether the power factor correction circuit PFC in the power detection circuit is enabled; if yes, execute step S4, if not, execute step S6.

[0129] S4, calculates the power factor PF according to the actual voltage and the actual current.

[0130] As mentioned above Figure 5As shown, after the first sampling voltage U1 and the second sampling voltage U2 are input into the power calculation module, the interception time T1 of the first sampling voltage is determined according to the first voltage threshold value |u1| and the first phase angle ∠u1; the interception time T2 of the second sampling voltage is determined according to the second voltage threshold value |u2| and the second voltage phase angle ∠u2; the time difference ΔT between the interception time T1 of the first sampling voltage and the interception time T2 of the second sampling voltage is obtained; the phase difference θ between the second sampling voltage and the first sampling voltage is obtained according to the time difference ΔT, and the cosine value cosθ of the phase difference is calculated; the first sampling voltage U1 is Fourier expanded, each harmonic content value THD is calculated, and then summed, and the summation formula is: in, is the value of the nth harmonic content; the product of the cosine value cosθ of the phase difference and the sum of the harmonic contents is calculated to obtain the power factor PF.

[0131] S5, determining the number of power calculations f(n) according to the power frequency, calculating the sum of the power calculation results according to the power factor PF and the number of power calculations, and obtaining the power of the electrical equipment.

[0132] The power calculation times are determined according to the power frequency of the power supply system. For example, the power frequency can be 50 Hz or 60 Hz. Then the common multiple of 50 and 60 is determined, preferably the least common multiple 300 is used as the power calculation times, and the power of the electrical equipment is calculated. Where n represents the number of calculations. In this embodiment, the time interval between two calculations is 200us. The total power is:

[0133] S6, obtaining a preset power factor cosθ1, calculating the product of the preset power factor cosθ1, the actual voltage U and the actual current I, and obtaining the power of the electrical equipment.

[0134] Specifically, the preset power factor=cosθ1, the power of the electrical equipment P=U*I*cosθ1, and the total power is P=U*I*cosθ1+P1.

[0135] S7, calculates the power consumption according to the total power and the power consumption time.

[0136] The power detection method of this embodiment calculates the power factor and power frequency of the power supply according to the actual unit requirements, meets the power calculation accuracy and compatibility requirements of different power supply frequencies, and performs compensation calculation on the rectifier thermal power. Considering the influence of power factor, power supply frequency, diode conduction voltage drop in the rectifier bridge and rectifier bridge on-state impedance, the calculation result is more accurate.

[0137] Example 6

[0138] This embodiment provides an electrical device, including the above-mentioned power detection circuit, so as to simplify the circuit and reduce the cost of the entire electrical device. The electrical device in this embodiment includes at least one of the following: an air conditioner, a washing machine, a refrigerator, a water heater, a fan, a dryer, an air purifier, a water purifier, and a pure water machine.

[0139] Example 7

[0140] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the power detection method in the above embodiment is implemented.

[0141] The circuit embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0142] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A power detection circuit, characterized in that: The power detection circuit comprises: A first sampling module is provided on a positive bus or a negative bus of a power supply system, and is used to obtain a first sampling voltage; A second sampling module is provided between the positive bus and the negative bus of the power supply system, and is used to divide the actual voltage input by the electrical equipment to obtain a second sampling voltage; A power calculation module, whose input ends are respectively connected to the first sampling module and the second sampling module, is used to calculate the actual current according to the first sampling voltage, obtain the actual voltage according to the second sampling voltage, and calculate the power of the electrical equipment according to the actual current, the actual voltage and the power factor; the power calculation module is also used to: determine whether the power factor correction circuit is enabled; if so, calculate the power factor according to the first sampling voltage and the second sampling voltage, and determine the number of power calculations according to the power supply frequency; calculate the sum of the power calculation results according to the power factor and the number of power calculations to obtain the power of the electrical equipment; if not, obtain a preset power factor, calculate the product of the preset power factor and the actual voltage and the actual current to obtain the power of the electrical equipment.

2. The power detection circuit according to claim 1, characterized in that: The power calculation module is also used to calculate the sum of the thermal power of the rectifier bridge in the power supply system and the power of the electrical equipment to obtain the total power.

3. The power detection circuit according to claim 1, characterized in that: The first sampling module comprises: A sampling resistor is arranged on the positive bus or the negative bus of the power supply system; A first voltage dividing unit, a first end of which is connected to the first end of the sampling resistor, a second end of which is connected to the first voltage source, and an output end of which is connected to the non-inverting input end of the operational amplifier; The operational amplifier, whose inverting input terminal is connected to the second end of the sampling resistor through a first resistor, and whose output terminal is connected to the power calculation module, is used to output the first sampling voltage; wherein the first sampling voltage is equal to the voltage difference between the two ends of the sampling resistor; The output terminal of the operational amplifier is also connected to the inverting input terminal of the operational amplifier itself through a second resistor.

4. The power detection circuit according to claim 3, characterized in that: The first voltage dividing unit comprises: A third resistor and a fourth resistor are arranged in series, the third resistor is connected to the first end of the sampling resistor, the fourth resistor is connected to the first voltage source, and a wire is led out between the third resistor and the fourth resistor, serving as the output end of the first voltage divider unit, and connected to the non-inverting input end of the operational amplifier.

5. The power detection circuit according to claim 4, characterized in that: The first voltage dividing unit further includes: The first capacitor is arranged in parallel at both ends of the fourth resistor, and is used to limit the magnitude of the voltage output by the first voltage dividing unit.

6. The power detection circuit according to claim 3, characterized in that: The first sampling module also includes: a fifth resistor, a first end of which is connected to the output end of the operational amplifier; a second capacitor, a first end of which is connected to the second end of the fifth resistor, and a second end of which is connected to the negative bus of the power supply system; The fifth resistor and the second capacitor are used to filter the first sampling voltage and output it through a wire between the fifth resistor and the second capacitor.

7. The power detection circuit according to claim 1, characterized in that: The second sampling module comprises: A second voltage dividing unit, having a first end connected to the positive bus of the power supply system, a second end connected to the negative bus of the power supply system, and an output end connected to the power calculation module, is used to output the second sampling voltage.

8. The power detection circuit according to claim 7, characterized in that: The second voltage dividing unit comprises: A sixth resistor and a seventh resistor are arranged in series, the sixth resistor is connected to the positive bus of the power supply system, the seventh resistor is connected to the negative bus of the power supply system, and a wire is led out between the sixth resistor and the seventh resistor as the output end of the second voltage divider unit.

9. The power detection circuit according to claim 8, characterized in that: The second sampling module also includes: A first voltage stabilizing unit and a second voltage stabilizing unit are connected in series in the same direction, the first voltage stabilizing unit is connected to a second voltage source, the second voltage stabilizing unit is connected to a negative bus of the power supply system, a wire is led out between the first voltage stabilizing unit and the second voltage stabilizing unit, and connected to the output end of the second voltage dividing unit, the first voltage stabilizing unit and the second voltage stabilizing unit are used to control the output voltage of the second voltage dividing unit.

10. The power detection circuit according to claim 8, characterized in that: The second sampling module also includes: An eighth resistor, a first end of which is an output end of the operational amplifier; a third capacitor, a first end of which is connected to the second end of the eighth resistor, and a second end of which is connected to the negative busbar of the power supply system; The eighth resistor and the third capacitor are used to filter the second sampling voltage and output it through a wire between the eighth resistor and the third capacitor.

11. The power detection circuit according to claim 1, characterized in that: The power detection circuit also includes a power factor correction circuit, and the power factor correction circuit includes: an inductor and a boost diode, wherein the inductor and the boost diode are connected in series and connected between a connection point between the second sampling module and the positive bus of the power supply system and a positive bus terminal of the power supply system; A switch tube, a first end of which is connected between the inductor and the boost diode, and a second end of which is connected to the negative bus of the power supply system.

12. An electrical device, characterized in that: The invention comprises the power detection circuit according to any one of claims 1 to 11.

13. The electrical device according to claim 12, characterized in that: The electrical equipment includes at least one of the following: Air conditioners, washing machines, refrigerators, water heaters, fans, dryers, air purifiers, water purifiers, and water purifiers.

14. A power detection method, applied to the power detection circuit according to any one of claims 1 to 11, characterized in that: The method comprises: Calculate the actual current according to the first sampled voltage, and calculate the actual voltage according to the second sampled voltage; The power factor is obtained according to the operating status of the power supply system, and the power of the electrical equipment is calculated according to the power factor, the actual current and the actual voltage; the method includes: determining whether the power factor correction circuit is enabled; if so, calculating the power factor according to the first sampling voltage and the second sampling voltage, and determining the number of power calculations according to the power supply frequency; calculating the sum of the results of each power calculation according to the power factor and the number of power calculations to obtain the power of the electrical equipment; if not, obtaining a preset power factor, calculating the product of the preset power factor and the actual voltage and the actual current to obtain the power of the electrical equipment.

15. The method according to claim 14, characterized in that Calculating the actual current according to the first sampled voltage includes: Calculating a sampling current according to the first sampling voltage, wherein the sampling current=the first sampling voltage / the resistance value of the sampling resistor; Amplifying the sampled current according to a first preset ratio to obtain an actual current; Calculating the actual voltage according to the second sampled voltage includes: The second sampled voltage is amplified by a second preset ratio to obtain an actual voltage.

16. The method according to claim 15, characterized in that Calculating a power factor according to the first sampled voltage and the second sampled voltage includes: Determining a time instant of capturing the first sampling voltage according to a first voltage threshold and a first phase angle; Determining a time instant for capturing the second sampling voltage according to a second voltage threshold and a second voltage phase angle; Obtaining a time difference between a time instant of intercepting the first sampling voltage and a time instant of intercepting the second sampling voltage; Acquire a phase difference between the second sampled voltage and the first sampled voltage according to the time difference, and calculate a cosine value of the phase difference; Performing Fourier expansion on the first sampled voltage to calculate the sum of each harmonic content; The power factor is obtained by calculating the product of the cosine value of the phase difference and the sum of the harmonic contents.

17. The method according to claim 15, characterized in that Determine the number of power calculations based on the power frequency, including: determining a first frequency and a second frequency of a power system; A common multiple of the first frequency and the second frequency is calculated as the number of power calculations.

18. The method according to claim 14, characterized in that After acquiring the power factor according to the operating state of the power supply system, and calculating the power of the electrical equipment according to the power factor, the actual current, and the actual voltage, the method further includes: Calculate the thermal power of the rectifier bridge in the power supply system; The sum of the thermal power of the rectifier bridge and the electrical equipment is calculated to obtain the total power.

19. The method according to claim 18, characterized in that The thermal power of the rectifier bridge in the power supply system is calculated based on the following formula: P1=r(t)×I 2 ; Wherein, P1 is the thermal power of the rectifier bridge, r(t) is the function of the change of the resistance of the rectifier bridge over time, and I is the actual current.

20. The method according to claim 18, characterized in that After obtaining the total power, the method further includes: The power consumption of the power-consuming device is calculated according to the total power and the power consumption time.

21. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 14 to 20 is implemented.

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