Power detection circuit and method and electric equipment
阅读说明：本技术 一种功率检测电路、方法及用电设备 (Power detection circuit and method and electric equipment ) 是由 方小斌 谭锋 侯辉 郑嘉良 黄银彬 于 2021-02-19 设计创作，主要内容包括：本发明公开一种功率检测电路、方法及用电设备。其中,该功率检测电路包括：第一采样模块,设置在供电系统的正极母线或者负极母线上,用于获得第一采样电压；第二采样模块,设置在供电系统的正极母线和负极母线之间,用于将用电设备输入的实际电压分压后,获得第二采样电压；功率计算模块,其输入端分别连接第一采样模块和所述第二采样模块,用于根据第一采样电压计算实际电流,根据所述第二采样电压获得实际电压,并根据所述实际电流、所述实际电压、功率因数计算所述用电设备的功率。通过本发明,能够在不设置采样偏置电路,差分运算电路和电流传感器的前提下进行功率检测,简化了电路结构,降低了成本。(The invention discloses a power detection circuit, a power detection method and electric equipment. Wherein, this power detection circuit includes: the first sampling module is arranged on a positive bus or a negative bus of the power supply system and used for obtaining a first sampling voltage; the second sampling module is arranged between the positive bus and the negative bus of the power supply system and used for obtaining a second sampling voltage after dividing the actual voltage input by the electric equipment; and the input end of the power calculation module is respectively connected with the first sampling module and the second sampling module and used for calculating actual current according to the first sampling voltage, obtaining actual voltage according to the second sampling voltage and calculating the power of the electric equipment according to the actual current, the actual voltage and the power factor. According to the invention, power detection can be carried out on the premise of not arranging a sampling bias circuit, a differential operation circuit and a current sensor, so that the circuit structure is simplified, and the cost is reduced.)
1. A power detection circuit, the power detection circuit comprising:
the first sampling module is arranged on a positive bus or a negative bus of the power supply system and used for obtaining a first sampling voltage;
the second sampling module is arranged between the positive bus and the negative bus of the power supply system and used for obtaining a second sampling voltage after dividing the actual voltage input by the electric equipment;
and the input end of the power calculation module is respectively connected with the first sampling module and the second sampling module and is used for calculating actual current according to the first sampling voltage, obtaining actual voltage according to the second sampling voltage and calculating the power of the electric equipment according to the actual current, the actual voltage and the power factor.
2. The power detection circuit of claim 1, wherein the power calculation module is further configured to calculate a sum of a thermal power of a rectifier bridge in the power supply system and a power of the powered device to obtain a total power.
3. The power detection circuit of claim 1, wherein the first sampling module comprises:
the sampling resistor is arranged on a positive bus or a negative bus of the power supply system;
the first end of the first voltage division unit is connected with the first end of the sampling resistor, the second end of the first voltage division unit is connected with a first voltage source, and the output end of the first voltage division unit is connected with the non-inverting input end of the operational amplifier;
the inverting input end of the operational amplifier is connected with the second end of the sampling resistor through a first resistor, and the output end of the operational amplifier is connected with the power calculation module and used for outputting the first sampling voltage; wherein the first sampling voltage is equal to a voltage difference across the sampling resistor;
the output end of the operational amplifier is also connected with the inverting input end of the operational amplifier through a second resistor.
4. The power detection circuit of claim 3, wherein the first voltage division unit comprises:
the third resistance and the fourth resistance that the series connection set up, the third resistance is connected the first end of sampling resistor, the fourth resistance is connected first voltage source, the third resistance with lead wire is drawn forth between the fourth resistance, as the output of first partial pressure unit connects operational amplifier's non inverting input end.
5. The power detection circuit of claim 4, wherein the first voltage division unit further comprises:
and the first capacitor is arranged at two ends of the fourth resistor in parallel and used for limiting the voltage output by the first voltage division unit.
6. The power detection circuit of claim 3, wherein the first sampling module further comprises:
a first end of the fifth resistor is connected with the output end of the operational amplifier;
a first end of the second capacitor is connected with a second end of the fifth resistor, and a second end of the second capacitor is connected with a negative bus of the power supply system;
and the fifth resistor and the second capacitor are used for filtering the first sampling voltage and outputting the filtered first sampling voltage through a wire between the fifth resistor and the second capacitor.
7. The power detection circuit of claim 1, wherein the second sampling module comprises:
and the first end of the second voltage division unit is connected into the positive bus of the power supply system, the second end of the second voltage division unit is connected into the negative bus of the power supply system, and the output end of the second voltage division unit is connected with the power calculation module and is used for outputting the second sampling voltage.
8. The power detection circuit of claim 7, wherein the second voltage division unit comprises:
the sixth resistor and the seventh resistor are connected in series, the sixth resistor is connected with a positive bus of the power supply system, the seventh resistor is connected with a negative bus of the power supply system, and a lead is led out between the sixth resistor and the seventh resistor and serves as an output end of the second voltage division unit.
9. The power detection circuit of claim 8, wherein the second sampling module further comprises:
the first voltage stabilizing unit is connected with a second voltage source, the second voltage stabilizing unit is connected with a negative bus of the power supply system, a lead is led out between the first voltage stabilizing unit and the second voltage stabilizing unit and is connected with the output end of the second voltage dividing unit, and the first voltage stabilizing unit and the second voltage stabilizing unit are used for controlling the output voltage of the second voltage dividing unit.
10. The power detection circuit of claim 8, wherein the second sampling module further comprises:
an eighth resistor having a first end connected to the output terminal of the operational amplifier;
a first end of the third capacitor is connected with a second end of the eighth resistor, and a second end of the third capacitor is connected with a negative bus of the power supply system;
and the eighth resistor and the third capacitor are used for filtering the second sampling voltage and outputting the second sampling voltage through a conducting wire between the eighth resistor and the third capacitor.
11. The power detection circuit of claim 1, further comprising a power factor correction circuit comprising:
the inductor and the diode are connected in series and then are connected between a connection point of the second sampling module and an anode bus of the power supply system and an anode bus terminal of the power supply system;
and a first end of the switching tube is connected between the inductor and the boost diode, and a second end of the switching tube is connected to a negative bus of the power supply system.
12. An electrical appliance comprising a power detection circuit as claimed in any one of claims 1 to 11.
13. The electrical device of claim 12, wherein the electrical device comprises at least one of:
air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.
14. A power detection method applied to the power detection circuit according to any one of claims 1 to 11, the method comprising:
calculating actual current according to the first sampling voltage, and calculating actual voltage according to the second sampling voltage;
and acquiring a power factor according to the running state of the power supply system, and calculating the power of the electric equipment according to the power factor, the actual current and the actual voltage.
15. The method of claim 14, wherein calculating an actual current from the first sampled voltage comprises:
calculating a sampling current according to the first sampling voltage, wherein the sampling current is equal to the resistance value of the first sampling voltage/sampling resistor;
amplifying the sampling current according to a first preset proportion to obtain an actual current;
calculating an actual voltage from the second sampled voltage, comprising:
and amplifying the second sampling voltage in a second preset proportion to obtain an actual voltage.
16. The method of claim 14, wherein obtaining a power factor according to an operating state of the power supply system, and calculating power of the electric device according to the power factor, the actual current, and the actual voltage comprises:
judging whether the power factor correction circuit is started or not;
if yes, calculating a power factor according to the first sampling voltage and the second sampling voltage, and determining the power calculation times according to the power supply frequency; calculating the sum of power calculation results of each time according to the power factor and the power calculation times to obtain the power of the electric equipment;
if not, obtaining a preset power factor, and calculating the product of the preset power factor and the actual voltage and the actual current to obtain the power of the electric equipment.
17. The method of claim 16, wherein calculating a power factor from the first sampled voltage and the second sampled voltage comprises:
determining the interception moment of the first sampling voltage according to a first voltage threshold and a first phase angle;
determining the interception moment of the second sampling voltage according to a second voltage threshold and a second voltage phase angle;
acquiring the time difference between the interception time of the first sampling voltage and the interception time of the second sampling voltage;
acquiring a phase difference between the second sampling voltage and the first sampling voltage according to the time difference, and calculating a cosine value of the phase difference;
carrying out Fourier expansion on the first sampling voltage, and calculating the sum of the content of each subharmonic;
and calculating the product of the cosine value of the phase difference and the sum of the contents of the harmonics to obtain the power factor.
18. The method of claim 16, wherein determining the number of power calculations based on the power supply frequency comprises:
determining a first frequency and a second frequency of a power supply system;
and calculating the common multiple of the first frequency and the second frequency as the power calculation times.
19. The method of claim 14, wherein after obtaining a power factor according to an operating state of the power supply system and calculating power of the powered device according to the power factor, the actual current, and the actual voltage, the method further comprises:
calculating the thermal power of a rectifier bridge in the power supply system;
and calculating the sum of the thermal power of the rectifier bridge and the electric equipment to obtain total power.
20. The method of claim 19, wherein the thermal power of a rectifier bridge in the power supply system is calculated according to the formula:
P1＝r(t)×I2；
wherein P1 is the thermal power of the rectifier bridge, r (t) is the resistance of the rectifier bridge as a function of time, and I is the actual current.
21. The method of claim 19, wherein after obtaining the total power, the method further comprises:
and calculating the power consumption of the electric equipment according to the total power and the power consumption time.
22. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, carries out the method according to any one of claims 14 to 21.
Technical Field
The invention relates to the technical field of electronic power, in particular to a power detection circuit, a power detection method and power utilization equipment.
Background
The power calculation accuracy of electric quantity metering is controlled within 5% for charging individual users of electric equipment or charging of shared electric equipment, fig. 1 is a conventional power detection circuit, and as shown in fig. 1, the conventional power detection circuit adopts a power input alternating current side AC to sample the voltage and current of an input power supply, and calculates an input power P-U-I power factor. A sampling circuit in the circuit also needs a 1.65V sampling bias circuit, a differential operation circuit and a current sensor, the circuit structure is complex, and the number of components is large, so that the power detection cost is high.
Aiming at the problem that the structure of a power detection circuit in the prior art is complex and further the cost is high, an effective solution is not provided at present.
Disclosure of Invention
The embodiment of the invention provides a power detection circuit, a power detection method and electric equipment, and aims to solve the problem that the power detection circuit in the prior art is complex in structure and further high in cost.
To solve the above technical problem, the present invention provides a power detection circuit, including:
the first sampling module is arranged on a positive bus or a negative bus of the power supply system and used for obtaining a first sampling voltage;
the second sampling module is arranged between a positive bus and a negative bus of the power supply system and used for obtaining a second sampling voltage after dividing the actual voltage input by the electric equipment;
and the input end of the power calculation module is respectively connected with the first sampling module and the second sampling module and is used for calculating actual current according to the first sampling voltage, obtaining actual voltage according to the second sampling voltage and calculating the power of the electric equipment according to the actual current, the actual voltage and the power factor.
Further, the power calculation module is further configured to calculate a sum of a thermal power of a rectifier bridge in the power supply system and a power of the electrical device, so as to obtain a total power.
Further, the first sampling module comprises:
the sampling resistor is arranged on a positive bus or a negative bus of the power supply system;
the first end of the first voltage division unit is connected with the first end of the sampling resistor, the second end of the first voltage division unit is connected with a first voltage source, and the output end of the first voltage division unit is connected with the non-inverting input end of the operational amplifier;
the inverting input end of the operational amplifier is connected with the second end of the sampling resistor through a first resistor, and the output end of the operational amplifier is connected with the power calculation module and used for outputting the first sampling voltage; wherein the first sampling voltage is equal to a voltage difference across the sampling resistor;
the output end of the operational amplifier is also connected with the inverting input end of the operational amplifier through a second resistor.
Further, the first voltage division unit includes:
the third resistance and the fourth resistance that the series connection set up, the third resistance is connected the first end of sampling resistor, the fourth resistance is connected first voltage source, the third resistance with lead wire is drawn forth between the fourth resistance, as the output of first partial pressure unit connects operational amplifier's non inverting input end.
Further, the first voltage division unit further includes:
and the first capacitor is arranged at two ends of the fourth resistor in parallel and used for limiting the voltage output by the first voltage division unit.
Further, the first sampling module further comprises:
a first end of the fifth resistor is connected with the output end of the operational amplifier;
a first end of the second capacitor is connected with a second end of the fifth resistor, and a second end of the second capacitor is connected with a negative bus of the power supply system;
and the fifth resistor and the second capacitor are used for filtering the first sampling voltage and outputting the filtered first sampling voltage through a wire between the fifth resistor and the second capacitor.
Further, the second sampling module comprises:
and the first end of the second voltage division unit is connected into the positive bus of the power supply system, the second end of the second voltage division unit is connected into the negative bus of the power supply system, and the output end of the second voltage division unit is connected with the power calculation module and is used for outputting the second sampling voltage.
Further, the second voltage division unit includes:
the sixth resistor and the seventh resistor are connected in series, the sixth resistor is connected with a positive bus of the power supply system, the seventh resistor is connected with a negative bus of the power supply system, and a lead is led out between the sixth resistor and the seventh resistor and serves as an output end of the second voltage division unit.
Further, the second sampling module further comprises:
the first voltage stabilizing unit is connected with a second voltage source, the second voltage stabilizing unit is connected with a negative bus of the power supply system, a lead is led out between the first voltage stabilizing unit and the second voltage stabilizing unit and is connected with the output end of the second voltage dividing unit, and the first voltage stabilizing unit and the second voltage stabilizing unit are used for controlling the output voltage of the second voltage dividing unit.
Further, the second sampling module further comprises:
an eighth resistor having a first end connected to the output terminal of the operational amplifier;
a first end of the third capacitor is connected with a second end of the eighth resistor, and a second end of the third capacitor is connected with a negative bus of the power supply system;
and the eighth resistor and the third capacitor are used for filtering the second sampling voltage and outputting the second sampling voltage through a conducting wire between the eighth resistor and the third capacitor.
Further, the power detection circuit further includes a power factor correction circuit, the power factor correction circuit including:
the inductor and the diode are connected in series and then are connected between a connection point of the second sampling module and an anode bus of the power supply system and an anode bus terminal of the power supply system;
and a first end of the switching tube is connected between the inductor and the boost diode, and a second end of the switching tube is connected to a negative bus of the power supply system.
The invention also provides electrical equipment which comprises the power detection circuit.
Further, the electrical device comprises at least one of:
air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.
The invention also provides a power detection method, which is applied to the power detection circuit and comprises the following steps:
calculating actual current according to the first sampling voltage, and calculating actual voltage according to the second sampling voltage;
and acquiring a power factor according to the running state of the power supply system, and calculating the power of the electric equipment according to the power factor, the actual current and the actual voltage.
Further, calculating an actual current from the first sampled voltage includes:
calculating a sampling current according to the first sampling voltage, wherein the sampling current is equal to the resistance value of the first sampling voltage/sampling resistor;
amplifying the sampling current according to a first preset proportion to obtain an actual current;
calculating an actual voltage from the second sampled voltage, comprising:
and amplifying the second sampling voltage in a second preset proportion to obtain an actual voltage.
Further, acquiring a power factor according to the operation state of the power supply system, and calculating the power of the electric equipment according to the power factor, the actual current and the actual voltage, including:
judging whether the power factor correction circuit is started or not;
if yes, calculating a power factor according to the first sampling voltage and the second sampling voltage, and determining the power calculation times according to the power supply frequency; calculating the sum of power calculation results of each time according to the power factor and the power calculation times to obtain the power of the electric equipment;
if not, obtaining a preset power factor, and calculating the product of the preset power factor and the actual voltage and the actual current to obtain the power of the electric equipment.
Further, calculating a power factor from the first sampled voltage and the second sampled voltage includes:
determining the interception moment of the first sampling voltage according to a first voltage threshold and a first phase angle;
determining the interception moment of the second sampling voltage according to a second voltage threshold and a second voltage phase angle;
acquiring the time difference between the interception time of the first sampling voltage and the interception time of the second sampling voltage;
acquiring a phase difference between the second sampling voltage and the first sampling voltage according to the time difference, and calculating a cosine value of the phase difference;
carrying out Fourier expansion on the first sampling voltage, and calculating the sum of the content of each subharmonic;
and calculating the product of the cosine value of the phase difference and the sum of the contents of the harmonics to obtain the power factor.
Further, determining the number of power calculations according to the power supply frequency includes:
determining a first frequency and a second frequency of a power supply system;
and calculating the common multiple of the first frequency and the second frequency as the power calculation times.
Further, after obtaining a power factor according to the operating state of the power supply system and calculating the power of the electric device according to the power factor, the actual current and the actual voltage, the method further includes:
calculating the thermal power of a rectifier bridge in the power supply system;
and calculating the sum of the thermal power of the rectifier bridge and the electric equipment to obtain total power.
Further, the thermal power of a rectifier bridge in the power supply system is calculated according to the formula:
P1＝r(t)×I2；
wherein P1 is the thermal power of the rectifier bridge, r (t) is the resistance of the rectifier bridge as a function of time, and I is the actual current.
Further, after obtaining the total power, the method further comprises:
and calculating the power consumption of the electric equipment according to the total power and the power consumption time.
The present invention also provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the above-described power detection method.
By applying the technical scheme of the invention, the first sampling module is arranged to obtain the first sampling voltage, the second sampling module is arranged to obtain the second sampling voltage, the power calculation module is used for calculating the actual current according to the first sampling voltage, calculating the actual voltage according to the second sampling voltage and calculating the power factor, a sampling bias circuit, a differential operation circuit and a current sensor are not needed, the circuit structure is simplified, and the cost is reduced.
Drawings
FIG. 1 is a conventional power detection circuit;
FIG. 2 is a block diagram of a power supply system and power detection circuitry according to an embodiment of the invention;
FIG. 3 is a block diagram of a power supply system and power detection circuitry according to another embodiment of the present invention;
FIG. 4 is a flow chart of a power detection method according to an embodiment of the invention;
FIG. 5 is a flow chart of power factor calculation according to an embodiment of the present invention;
fig. 6 is a flowchart of a power detection method according to another embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that although the terms first, second, etc. may be used to describe the sampled voltages in embodiments of the present invention, the sampled voltages should not be limited to these terms. These terms are only used to distinguish between sampled voltages obtained by different sampling modules. For example, the first sampled voltage may also be referred to as a second sampled voltage, and similarly, the second sampled voltage may also be referred to as a first sampled voltage without departing from the scope of embodiments of the present invention.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in the article or device in which the element is included.
Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Example 1
The present embodiment provides a power detection circuit, which is applied to a power supply system, and fig. 2 is a structural diagram of the power supply system and the power detection circuit according to the embodiment of the present invention, as shown in fig. 2, the power supply system includes: the rectifier bridge DB1 and the rectifier bridge DB1 comprise at least four diodes, the four diodes are connected in series in a pairwise reverse direction to form two rectifier bridge arms respectively, and the two bridge arms are arranged between a live wire terminal AC-L and a zero line terminal AC-N of an alternating current power supply in parallel. And a circuit led out between the two diodes connected in series in the reverse direction of the first rectifying bridge arm is an anode bus P of the power supply system, and a circuit led out between the two diodes connected in series in the reverse direction of the second rectifying bridge arm is a cathode bus GDN _ DRIVE of the power supply system. The alternating current input power AC rectifies the sinusoidal current U0 into a direct current power DC of a 'steamed bun' wave through a rectifier bridge DB1, rectifies alternating current output by the alternating current power AC through a diode in a rectifier bridge DB1 to form a direct current power voltage of the 'steamed bun' wave, namely, the amplitude of the alternating current voltage below 0.7V is turned over to be above 0.7V and is output to a positive bus P and a negative bus GND _ DRIVE to be used as an input power of a power factor correction circuit PFC and supply power to the electric equipment side of the inverter circuit.
The power detection circuit includes: the first sampling module 10 is arranged on a positive bus or a negative bus of a power supply system and used for obtaining a first sampling voltage; the second sampling module 20 is arranged between the positive bus P and the negative bus GDN _ DRIVE of the power supply system, and is used for obtaining a second sampling voltage after dividing the actual voltage input by the electric equipment;
and the input end of the power calculation module 30 is connected to the first sampling module 10 and the second sampling module 20, and is configured to calculate an actual current I according to the first sampling voltage U1, obtain an actual voltage U according to the second sampling voltage U2, and calculate the power of the electrical device according to the actual current I, the actual voltage U, and the power factor PF.
According to the technical scheme, the first sampling module is arranged to obtain the first sampling voltage, the second sampling module is arranged to obtain the second sampling voltage, the power calculation module is used for calculating the actual current according to the first sampling voltage, calculating the actual voltage according to the second sampling voltage and calculating the power factor, a sampling bias circuit, a differential operation circuit and a current sensor are not needed, the circuit structure is simplified, and the cost is reduced.
In other embodiments of the present invention, the power calculating module 30 may be further configured to calculate a sum of a thermal power of a rectifier bridge in the power supply system and a power of the electric device, so as to obtain the total power.
Example 2
In this embodiment, another power detection circuit is provided, and fig. 3 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, which allows the maximum voltage of the input to be low (generally 3.3V), in order to control the first sampling voltage, as shown in fig. 3, the first sampling module 10 includes: the sampling resistor RS1 is arranged on a positive bus P or a negative bus of the power supply system; the first voltage division unit 101 is connected with the first end of the sampling resistor RS1 at the first end, connected with a first voltage source at the second end and connected with the non-inverting input end + of the operational amplifier U16-B at the output end; the inverting input end of the operational amplifier U16-B is connected with the second end of the sampling resistor RS1 through the first resistor R1, and the output end of the operational amplifier U16-B is connected with the power calculation module 30 and is used for outputting a first sampling voltage U1; the first sampling voltage U1 is equal to the voltage difference between two ends of the sampling resistor RS 1; the output of the operational amplifier U16-B is also connected to the inverting input-of the operational amplifier U16-B itself through a second resistor R2.
The first voltage division unit 101 includes: the sampling circuit comprises a third resistor R3 and a fourth resistor R4 which are arranged in series, wherein the third resistor R3 is connected with a first end of the sampling resistor RS1, the fourth resistor R4 is connected with the first voltage source, a lead is led out between the third resistor R3 and the fourth resistor R4 and used as an output end of the first voltage division unit, and the output end of the first voltage division unit is connected with a non-inverting input end + of the operational amplifier U16-B.
As described above, since the power calculation module 30 is generally a chip which allows the maximum voltage of the input to be low (generally 3.3V), in order to control the first sampling voltage U1, the first voltage division unit 101 further includes: and a first capacitor C1, disposed in parallel across the fourth resistor R4, for limiting the magnitude of the voltage output by the first voltage division unit 101.
The waveform of the first sampled voltage U1 is not necessarily smooth, and may have jaggies or spikes, and in order to eliminate the jaggies or spikes in the waveform of the first sampled voltage U1, the first sampling module 10 further includes: a first end of the fifth resistor R5 is connected with the output end of the operational amplifier U16-B; a first end of the second capacitor C2 is connected with a second end of the fifth resistor R5, and a second end of the second capacitor C2 is connected with a negative bus GND _ DRIVE of the power supply system;
the fifth resistor R5 and the second capacitor C2 are used for filtering the first sampled voltage U1 and outputting the filtered first sampled voltage U1 through a wire between the fifth resistor R5 and the second capacitor C2.
To obtain a smaller second sampled voltage due to the larger actual voltage, the second sampling module 20 includes: a first end of the second voltage division unit 201 is connected to the positive bus P of the power supply system, a second end of the second voltage division unit is connected to the negative bus GND _ DRIVE of the power supply system, and an output end of the second voltage division unit is connected to the power calculation module 30 and is configured to output a second sampling voltage to the power calculation module 30.
Specifically, the second voltage division unit 201 includes: the sixth resistor R6 and the seventh resistor R7 are arranged in series, the sixth resistor R6 is connected with the positive bus P of the power supply system, the seventh resistor R7 is connected with the negative bus GND _ DRIVE of the power supply system, and a lead is led out between the sixth resistor R6 and the seventh resistor R7 to serve as the output end of the second voltage division unit 201. It should be noted that the sixth resistor R6 and the seventh resistor R7 may be a single resistor or may be formed by connecting a plurality of small resistors in series, and the present invention is not limited in particular.
In order to further avoid that the value of the second sampling voltage exceeds the maximum voltage allowed to be input by the power calculation module 30, the second sampling module 20 further includes:
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 a second voltage source, the second voltage stabilizing unit D2 is connected to a negative bus GND _ DRIVE of the power supply system, a conducting wire is led out between the first voltage stabilizing unit D1 and the second voltage stabilizing unit D2 and is connected to the output end of the second voltage dividing unit 201, and the first voltage stabilizing unit D1 and the second voltage stabilizing unit D2 are used for controlling the output voltage of the second voltage dividing unit 201 so that the output voltage does not exceed the maximum voltage allowed to be input by the power calculating module 30, wherein the voltage value provided by the second voltage source can be set as the maximum voltage allowed to be input by the power calculating module 30.
The waveform of the second sampled voltage U2 is not necessarily smooth, and may have jaggies or spikes, and in order to eliminate the jaggies or spikes in the waveform of the second sampled voltage U2, the second sampling module 20 further includes: an eighth resistor R6, a first end of which is the output 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;
the eighth resistor R6 and the third capacitor C3 are used for filtering the second sampled voltage U2 and outputting the filtered second sampled voltage U2 through a wire between the eighth resistor R6 and the third capacitor C3.
In practical applications, the power factor may be inaccurate due to the phase change of the input current and the input voltage, and therefore, in this embodiment, the power detection circuit further includes a power factor correction circuit PFC, and the power factor correction circuit PFC includes: the inductor L and the boost diode D3 are connected in series and then connected to a connection point of the second sampling module 20 and the positive bus P of the power supply system and between the connection point and the positive bus terminal of the power supply system; and a first end of the switching tube Q is connected between the inductor L and the boost diode D3, and a second end of the switching tube Q is connected to a negative bus GND _ DRIVE of the power supply system.
Example 3
Fig. 4 is a flowchart of a power detection method according to an embodiment of the present invention, and as shown in fig. 4, the method includes:
and S101, calculating actual current according to the first sampling voltage, and calculating actual voltage according to the second sampling voltage.
Since the calculation power needs to obtain the actual current and the actual voltage, while 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 realize the calculation power, the actual current needs to be calculated according to the first sampling voltage, and the actual voltage needs to be calculated according to the second sampling voltage.
And S102, acquiring a power factor according to the running state of the power supply system, and calculating the power of the electric equipment according to the power factor, the actual current and the actual voltage.
Wherein, the running state of power supply system includes: the power factor correction circuit is enabled and the power factor correction circuit is not enabled, and calculation methods of the power factors are different for the two states.
According to the technical scheme of the embodiment, the actual current is calculated according to the first sampling voltage, and the actual voltage is calculated according to the second sampling voltage; and then acquiring the power factor according to the running state of the power supply system, and calculating the power of the electric equipment according to the power factor, the actual current and the actual voltage. In the sampling process, a sampling bias circuit, a differential operation circuit and a current sensor are not needed, the circuit structure is simplified, and the cost is reduced.
Example 4
This example provides another power detection method, in which, since the first sampling module directly obtains the voltage across the sampling resistor instead of the current, to achieve power calculation, obtaining the actual current according to the first sampling voltage includes: calculating a sampling current according to the first sampling voltage, wherein the sampling current is equal to the resistance value of the first sampling voltage/sampling resistor; since the sampling current is obtained by reducing the actual current according to the first preset proportion, the sampling current needs to be amplified according to the first preset proportion to obtain the actual current. And the second sampling voltage is obtained by dividing the voltage according to a second preset proportion according to the actual voltage, so that the calculation of the actual voltage according to the second sampling voltage comprises the following steps: and amplifying the second sampling voltage in a second preset proportion to obtain the actual voltage.
After the actual current and the actual voltage are obtained, a power factor needs to be obtained according to an operation state of a power supply system, and the power of the electric device is calculated according to the power factor, the actual current, and the actual voltage, which specifically includes: judging whether the power factor correction circuit is started or not; if yes, calculating a power factor according to the first sampling voltage and the second sampling voltage, and determining the power calculation times according to the power supply frequency; calculating the sum of power calculation results of each time according to the power factor and the power calculation times to obtain the power of the electric equipment; if not, obtaining a preset power factor, and calculating the product of the preset power factor and the actual voltage and the actual current to obtain the power of the electric equipment.
Fig. 5 is a flowchart of calculating a power factor according to an embodiment of the present invention, and as shown in fig. 5, calculating a power factor according to the first and second sampling voltages includes:
determining a interception moment T1 of the first sampling voltage according to a first voltage threshold | u1| and a first phase angle × [ u 1; determining a interception moment T2 of the second sampling voltage according to a second voltage threshold | u2| and a second voltage phase angle & 2; acquiring the time difference delta T between the interception time T1 of the first sampling voltage and the interception time T2 of the second sampling voltage; acquiring a phase difference theta between the second sampling voltage and the first sampling voltage according to the time delta T difference, and calculating a cosine value cos theta of the phase difference; fourier expansion is carried out on the first sampling voltage U1, each subharmonic content value THD is calculated and summed, and the summation formula isWherein the content of the first and second substances,is the nth harmonic content value; and calculating the product of the cosine value cos theta of the phase difference and the sum of the contents of the harmonics to obtain the power factor PF.
To ensure that the method is applicable regardless of whether the power supply frequency is the first frequency or the second frequency, determining the number of power calculations based on the power supply frequency comprises: determining a first frequency and a second frequency of a power supply system; and calculating the common multiple of the first frequency and the second frequency as the power calculation times. For example, if the power frequency can be 50Hz or 60Hz, a common multiple of 50 and 60 is determined, preferably a minimum common multiple of 300 is determined as the number of power calculations, the power of the electrical device is calculated, and the electrical device is poweredWhere n represents the number of calculations, in this embodiment, every two calculations are separated by 200 us.
Because the power supply system also comprises a rectifier bridge, in order to ensure the accuracy of a power calculation value, the power factor is obtained according to the running state of the power supply system, and after the power of the electric equipment is calculated according to the power factor, the actual current and the actual voltage, the method also comprises the following steps: calculating the thermal power of a rectifier bridge in the power supply system; and calculating the sum of the thermal power of the rectifier bridge and the electric equipment to obtain total power. Calculating the thermal power of a rectifier bridge in the power supply system according to the formula: p1 ═ r (t) × I2(ii) a Wherein P1 is the thermal power of the rectifier bridge, r (t) is the resistance of the rectifier bridge as a function of time, and I is the actual current. After the total power is obtained, the power consumption of the electric equipment can be calculated according to the total power and the power consumption time.
Example 5
The present embodiment provides a power detection circuit applied to a power supply system, as shown in fig. 3 mentioned above, the power supply system including: the rectifier bridge DB1 and the rectifier bridge DB1 comprise at least four diodes, the four diodes are connected in series in a pairwise reverse direction to form two rectifier bridge arms respectively, and the two bridge arms are arranged between a live wire terminal AC-L and a zero line terminal AC-N of an alternating current power supply in parallel. And a circuit led out between the two diodes connected in series in the reverse direction of the first rectifying bridge arm is an anode bus P of the power supply system, and a circuit led out between the two diodes connected in series in the reverse direction of the second rectifying bridge arm is a cathode bus GDN _ DRIVE of the power supply system. The alternating current input power AC rectifies the sinusoidal current U0 into a direct current power DC of a 'steamed bun' wave through a rectifier bridge DB1, rectifies alternating current output by the alternating current power AC through a diode in a rectifier bridge DB1 to form a direct current power voltage of the 'steamed bun' wave, namely, the amplitude of the alternating current voltage below 0.7V is turned over to be above 0.7V and is output to a positive bus P and a negative bus GND _ DRIVE to be used as an input power of a power factor correction circuit PFC and supply power to the electric equipment side of the inverter circuit.
As shown in fig. 3, the power detection circuit includes a first sampling module 10, which collects a first voltage from a negative bus GND _ DRIVE end and obtains an actual current I. The first sampling module 10 comprises a sampling resistor RS1 connected in series to the negative bus GND _ DRIVE, a first resistor R1R1 and 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 of the third resistor R3 is connected to the fourth resistor R4, the other end of the fourth resistor R4 is connected to a first voltage source, a lead 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 of the operational amplifier U16-B is connected to the power calculation module 30, the non-inverting input terminal of the operational amplifier U16-B is connected to the power calculation module 30 through the second resistor R2, and a first sampling voltage U1 output by the operational amplifier U16-B is low-pass through the fifth. A1.65V sampling bias circuit, a differential operation circuit and a current sensor of a conventional circuit are omitted.
As shown in fig. 3, the power detection module further includes a second sampling module 20, the second sampling module 20 includes a sixth resistor R6 and a seventh resistor R7, and after the sixth resistor R6 and the seventh resistor R7 are connected in series, one end of the sixth resistor R6 is connected to the positive bus P, and the other end of the sixth resistor R7 is connected to the negative bus GND _ DRIVE. The sixth resistor R6 and the seventh resistor R7 output a 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 may be a single resistor or may be formed by connecting a plurality of small resistors in series, which is not limited in the present invention.
In order to ensure that the second sampling voltage U2 does not exceed the maximum voltage (e.g. 3.3V) allowed to be input by the power calculation module 30, the first voltage stabilization unit D1 and the second voltage stabilization unit D2 are connected in series in the same direction, the first voltage stabilization unit D1 is connected to a second voltage source (the voltage provided by the second voltage source is equal to the maximum voltage allowed to be input by the power calculation module 30), the second voltage stabilization unit D2 is connected to the negative bus GND _ DRIVE, a lead is led out between the first voltage stabilization unit D1 and the second voltage stabilization unit D2 and is connected between the sixth resistor R6 and the seventh resistor R7, and the first voltage stabilization unit D1 and the second voltage stabilization unit D2 are used for controlling the magnitude of the second sampling voltage to not exceed the maximum voltage allowed to be input by the power calculation module 30 through clamping.
The power detection circuit of the embodiment adopts the sampling of the voltage and the current of the direct current DC side of the input power supply, and can realize the lean design requirements of simple circuit, few components, low cost and high reliability.
This embodiment also provides another power detection method, and fig. 6 is a flowchart of a power detection method according to another embodiment of the present invention, as shown in fig. 6, the method includes:
and S1, converting the actual current I and the actual voltage U according to the first sampled voltage U1 and the second sampled voltage U2.
For example: the sampled current I1 is the actual current I x the first sampling coefficient K1, and the actual current I is the sampled current I1/the first sampling coefficient K1; the sampling current I1 is equal to the resistance of the first sampling voltage U1/the sampling resistor RS1, where K1 is determined by the resistances of the first resistor R1, the second resistor R2, the third resistor R3, and the third resistor R4, and may be set to 0.06; the second sampling voltage U2 is the actual voltage U × the second sampling coefficient K2, and the actual voltage U is the second sampling voltage U2/the second sampling coefficient K2, where K2 is determined by resistances of the sixth resistor R6 and the seventh resistor R7, and K2 may be equal to 0.0055, and in a specific implementation, it is required to ensure that the first sampling voltage U1 and the second sampling voltage are less than 3.3V.
And S2, calculating the thermal power of a rectifier bridge in the power supply system.
In this embodiment, because of the existence of the rectifier bridge, the input power calculation compensation is required, and the thermal power of the rectifier bridge in the power supply system is calculated according to the following formula: p1 ═ r (t) × I2(ii) a Wherein P1 is the thermal power of the rectifier bridge, r (t) is the resistance of the rectifier bridge as a function of time, and I is the actual current.
S3, judging whether a Power Factor Correction (PFC) circuit in the power detection circuit is started; if so, step S4 is performed, and if not, step S6 is performed.
S4, a power factor PF is calculated from the actual voltage and the actual current.
As shown in fig. 5 mentioned above, after the first sampled voltage U1 and the second sampled voltage U2 are input into the power calculation module, the intercept time T1 of the first sampled voltage is determined according to the first voltage threshold | U1| and the first phase angle & 1; determining a interception moment T2 of the second sampling voltage according to a second voltage threshold | u2| and a second voltage phase angle & 2; acquiring the time difference delta T between the interception time T1 of the first sampling voltage and the interception time T2 of the second sampling voltage; acquiring a phase difference theta between the second sampling voltage and the first sampling voltage according to the time delta T difference, and calculating a cosine value cos theta of the phase difference; fourier expansion is carried out on the first sampling voltage U1, each subharmonic content value THD is calculated and summed, and the summation formula isWherein the content of the first and second substances,is the nth harmonic content value; and calculating the product of the cosine value cos theta of the phase difference and the sum of the contents of the harmonics to obtain the power factor PF.
And S5, determining the power calculation times f (n) according to the power supply frequency, and calculating the sum of the power calculation results of each time according to the power factor PF and the power calculation times to obtain the power of the electric equipment.
Determining the number of power calculations according to the power supply frequency of the power supply system, for example, the power supply frequency can be 50Hz or 60Hz, determining a common multiple of 50 and 60, preferably a minimum common multiple of 300, as the number of power calculations, calculating the power of the electric device, and calculating the power of the electric device Where n represents the number of calculations, in this embodiment, every two calculations are separated by 200 us. The total power is:
and S6, obtaining a preset power factor cos theta 1, and calculating the product of the preset power factor cos theta 1, the actual voltage U and the actual current I to obtain the power of the electric equipment.
Specifically, the preset power factor is cos θ 1, the power P of the electric device is U × I cos θ 1, and the total power P is U × I cos θ 1+ P1.
And S7, calculating the electricity consumption according to the total power and the electricity utilization time.
According to the power detection method, the power factor and the power frequency of the power supply are calculated according to the actual unit requirements, the power calculation precision and the compatibility requirements of different power frequencies are met, and meanwhile, the rectification thermal power is subjected to compensation calculation. The calculation result is more accurate by considering the influences of power factors, power supply frequency, diode conduction voltage drop in the rectifier bridge, on-state impedance of the rectifier bridge and the like.
Example 6
The embodiment provides an electrical device, which comprises the power detection circuit. The circuit is simplified, and the cost of the whole electrical equipment is reduced. The electrical equipment in this embodiment includes at least one of the following: air conditioner, washing machine, refrigerator, water heater, fan, drying-machine, air purifier, water purification machine.
Example 7
The present embodiment provides a computer-readable storage medium on which a computer program is stored, which when executed by a processor implements the power detection method in the above-described embodiments.
The above-described circuit embodiments are only illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
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