CN114879035A - System and method for rapidly calculating electric parameters of motor - Google Patents

System and method for rapidly calculating electric parameters of motor Download PDF

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Publication number
CN114879035A
CN114879035A CN202210624906.5A CN202210624906A CN114879035A CN 114879035 A CN114879035 A CN 114879035A CN 202210624906 A CN202210624906 A CN 202210624906A CN 114879035 A CN114879035 A CN 114879035A
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motor
resistor
pin
output signal
data
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郑军
袁国堂
张林友
孙红辉
王雪燕
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Taizhou Guangzhong Electrical Equipment Co ltd
Research Institute of Zhejiang University Taizhou
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Taizhou Guangzhong Electrical Equipment Co ltd
Research Institute of Zhejiang University Taizhou
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage

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Abstract

The invention relates to a system and a method for rapidly calculating electric parameters of a motor, wherein a frequency detection circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a comparator U1; a 7 pin of the comparator U1 is connected with a 5V power supply, and a 4 pin is grounded; the 3 pin of the comparator U1 is connected with a resistor R3, and the other end of the resistor R3 is connected with an output signal of the motor; a second pin of the comparator U1 is respectively connected with one end of a resistor R1, a resistor R2 and one end of a capacitor C2, the other ends of a capacitor C2 and a resistor R1 are grounded, and the other end of the resistor R2 is connected with a 5V power supply; an 8 pin of the comparator U1 is grounded, the 8 pin is also connected with one end of a capacitor C1, and the other end of the capacitor C1 is connected with a 5V power supply; the 6 pin of the comparator U1 is used as an output; by setting the data groups, effective data corresponding to the output signals are not required to be calculated after periodic sampling is finished, but the effective data can be output after sampling of at least one data group is finished, and waiting time is reduced.

Description

System and method for rapidly calculating electric parameters of motor
Technical Field
The invention relates to the field of motors, in particular to a system and a method for rapidly calculating motor electrical parameters.
Background
In the system test of the motor, the electrical parameters of the voltage, the current, the power and the like of the motor are necessary parameters for measuring the performance of the motor and calculating the efficiency of the motor. In particular, when a high-power test or a locked-rotor test is performed on the motor, it is also required to acquire relevant electrical parameters of the motor in a short time, otherwise irreversible damage may be caused to the motor or a driver. Effective value of voltage (U) of motor in conventional motor performance test RMS ) Effective value of current (I) RMS ) And active power (P) are calculated from the sampled data over a period, typically requiring multiple cycles of sampling and acquisition based on the electrical parameters of each operating cycle. However, when the rotating speed of the motor is very low or is close to locked-rotor, the frequency F of the input signal is very low, which means that the period is relatively long, and the traditional data sampling and calculating method is adopted, so that the numerical values of a plurality of periods need to be collected, the waiting time is relatively long, the rapid test of the motor is not facilitated, and the motor and other equipment are easily damaged in the test process. There is therefore a need for a method of accurately obtaining electromechanical parameters over a relatively short period of operation.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a system and a method for quickly calculating the electrical parameters of a motor, which have the advantages of simple structure and convenience in use and can accurately obtain the electrical parameters of the motor in a few periods.
A frequency detection circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a comparator U1; the comparator U1 adopts TLV3501 integrated chip; a 7 pin of the comparator U1 is connected with a 5V power supply, and a 4 pin is grounded; the 3 pin of the comparator U1 is connected with a resistor R3, and the other end of the resistor R3 is connected with an output signal of the motor; a second pin of the comparator U1 is respectively connected with one end of a resistor R1, a resistor R2 and one end of a capacitor C2, the other ends of a capacitor C2 and a resistor R1 are grounded, and the other end of the resistor R2 is connected with a 5V power supply; an 8 pin of the comparator U1 is grounded, the 8 pin is also connected with one end of a capacitor C1, and the other end of the capacitor C1 is connected with a 5V power supply; the pins 1 and 5 of the comparator U1 are connected in a null mode, the pin 6 serves as an output, and the resistance value of the resistor R1 is equal to that of the resistor R2.
A method for rapidly calculating an electrical parameter of an electric machine, comprising the steps of:
step 1: obtaining an output signal of the motor, measuring the frequency of the output signal, and distorting the frequency through the frequency detection circuit to obtain a frequency f; wherein the output signal comprises an output voltage and an output current;
step 2: sampling according to a set AD sampling rate; the AD sampling rate is set to be 500k, and the sampling number of the output signal of the motor in one period is 500 k/f;
and step 3: dividing the sampling number in each period into y parts;
and 4, step 4: calculating each data to obtain a voltage data set, a current data set and a power data set;
and 5: obtaining valid data corresponding to an output signal according to the n-th to (y + n-1) data sets of each type of data, wherein n is 1,2 and 3 …; where n represents the nth valid data period.
Further, in the step 4, the voltage data group UU ADD The calculation of (d) is expressed as:
Figure BDA0003676654440000021
wherein y represents the average number of samples in each period as y; f represents the output frequency of the motor; 500k/yf represents the sampling number average fraction in one period of the output signal of the motorIs the number of samples per portion after y portions, U i Sample data representing a voltage;
current data set II ADD The calculation of (d) is expressed as:
Figure BDA0003676654440000022
wherein I i Sample data representing the current;
power data set PUI ADD The calculation of (d) is expressed as:
Figure BDA0003676654440000023
further, in the step 5, the voltage effective value is calculated by combining the traditional voltage effective value calculation formula (5) and is improved by:
Figure BDA0003676654440000024
wherein UU ADDj Representing a jth group of voltage data sets; n represents the number of samples in one period, N is 500k/f, U RMS Representing the effective value of the voltage.
Further, in the step 5, the current effective value is calculated by combining the traditional current effective value calculation formula (6) and is improved:
Figure BDA0003676654440000025
wherein II ADDj Representing the jth group of voltage data, I RMS Representing the effective value of the current.
Further, in the step 5, the improvement is obtained by combining the traditional active power calculation formula with the formula (7):
Figure BDA0003676654440000026
wherein the PUI ADDj And (4) representing a jth group power data group, and P representing active power.
Further, in step 5, the power factor PF of the motor is expressed as:
Figure BDA0003676654440000031
further, y is 20, which means that the sampling number of each period is 20 parts, and the number of the parts is 25 k/f.
The invention has the beneficial effects that:
according to the invention, by setting the data groups, effective data corresponding to the output signals are not required to be calculated after periodic sampling is finished, but the effective data can be output after sampling of at least one data group is finished, so that the waiting time is reduced;
compared with the traditional method, the method has the advantages that more effective data can be obtained for the motor output signals with the same time length, the samples of the effective data are richer, and the obtained conclusion is more accurate;
through the form of data array, carry out the operation of cumulant multiplication in groups to directly call the data array of cumulant multiplication and add up the operation, the calculated amount of the repeating data that has significantly reduced reduces the load of arithmetic equipment, and has improved data processing speed, has shortened the time of obtaining motor operating parameter.
Drawings
Fig. 1 is a schematic diagram of a frequency detection circuit according to a first embodiment of the invention;
FIG. 2 is a schematic diagram of detecting frequency according to a conventional method;
FIG. 3 is a schematic diagram of glitch and noise interference at a zero crossing point when detecting frequency according to a conventional method;
FIG. 4 is a waveform diagram of the compared output of the detection circuit according to the first embodiment of the present invention;
FIG. 5 is a flowchart of a method according to a first embodiment of the present invention;
fig. 6 is a schematic diagram of an effective data period according to a first embodiment of the invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The first embodiment is as follows:
as shown in fig. 1, a frequency detection circuit includes a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2, and a comparator U1, where the comparator U1 uses TLV3501 as an integrated chip. The 7 pin of the comparator U1 is connected with a 5V power supply, and the 4 pin is grounded. The 3 pin of the comparator U1 is connected with a resistor R3, and the other end of the resistor R3 is connected with an output signal of the motor. The second pin of the comparator U1 is connected to one end of a resistor R1, a resistor R2, and a capacitor C2, the other ends of the capacitor C2 and the resistor R1 are grounded, and the other end of the resistor R2 is connected to a 5V power supply. The 8 pin of the comparator U1 is grounded, the 8 pin is also connected with one end of a capacitor C1, and the other end of the capacitor C1 is connected with a 5V power supply. Wherein, the 1 pin and the 5 pin of the comparator U1 are both connected in a null way, and the 6 pin is used as an output.
The resistance values of the resistor R1 and the resistor R2 are equal, and in the example, the resistance values are both 5.1k ohms; the resistance value of the resistor R3 is 1k ohm; the capacitance C1 and the capacitance C2 are both 100 nf.
2-4, in the implementation process, the voltage is divided by the resistor R1 and the resistor R2, so that the voltage value at the 2 pin of the comparator U1 is 2.5V; the output signal of the motor passes through the detection circuit of the embodiment, if the output signal of the motor is higher than 2.5V, the 6 pin outputs high level, otherwise, the output signal outputs low level. In a traditional detection mode, the frequency of a signal is obtained by detecting the zero crossing point of an output signal of a motor, but because signal burrs and interference exist at the zero crossing point of the signal, an error is easy to generate, and for a high-frequency signal, the influence of the error is amplified, and even the measurement result is influenced; therefore, in the embodiment, the output signal of the motor is distorted by the detection circuit, the zero crossing point is deviated, the problem of signal glitch and noise interference of a zero position accessory is solved, and the frequency output by the pin of the detection circuit 6 is not changed.
As shown in fig. 5, a method for rapidly calculating an electrical parameter of a motor includes the following steps:
step 1: obtaining an output signal of the motor, measuring the frequency of the output signal, and distorting the frequency through the frequency detection circuit to obtain a frequency f; wherein the output signal comprises an output voltage and an output current;
step 2: sampling according to a set AD sampling rate; in this example the AD sampling rate is 500k, where the number of samples in one period of the output signal of the motor is 500 k/f;
and step 3: dividing the sampling number in each period into y parts; the sampling number of each period is 20 parts in the example, wherein the number of the parts is 25 k/f;
and 4, step 4: calculating each data to obtain a voltage data set, a current data set and a power data set;
and 5: obtaining valid data corresponding to an output signal according to the n-th to (y + n-1) data sets of each type of data, wherein n is 1,2 and 3 …; where n represents the nth valid data period.
Conventional effective value of voltage (U) RMS ) The calculation is as follows:
Figure BDA0003676654440000051
wherein U is i Representing the sampled data of the voltage, N represents the number of samples in a cycle, N being 500k/f in this example.
Similarly, the conventional effective value of the current (I) RMS ) And the calculation of the active power (P) is respectively shown as formulas (2) and (3):
Figure BDA0003676654440000052
Figure BDA0003676654440000053
wherein I i Sampled data representing current.
Obtaining the power factor PF of the motor according to the voltage effective value, the current effective value and the active power as follows:
Figure BDA0003676654440000054
in the step 4, the voltage data group UU ADD The calculation of (a) is expressed as:
Figure BDA0003676654440000055
wherein y represents the average number of samples in each period as y; f represents the output frequency of the motor; 500k/yf represents the number of samples per unit of the motor output signal divided into y parts.
Current data set II ADD The calculation of (d) is expressed as:
Figure BDA0003676654440000056
power data set PUI ADD The calculation of (a) is expressed as:
Figure BDA0003676654440000057
in the step 5, the voltage effective value is calculated by combining the formula (1) and the formula (5) and is improved:
Figure BDA0003676654440000058
wherein UU ADDj Represents a jth group of voltage data; n represents the number of samples in a period, which in this example is 500 k/f.
The calculation formula (2) is combined with the improvement formula (6) to obtain the current effective value:
Figure BDA0003676654440000059
wherein II ADDj Representing the jth set of voltage data.
The method is obtained by combining the traditional active power calculation formula (3) with the improvement of the formula (7):
Figure BDA0003676654440000061
wherein the PUI ADDj Representing the jth group of power data sets.
As shown in fig. 6, the frequency of the output signal waveform of the motor in this example is 50Hz, the obtained output period is 20ms, and the number of samples in one period is 10000 samples according to the AD sampling rate of 500 k. The data in one period is divided into 20 parts equally, and the number of samples in one part of data is 500. By adopting the method, the first effective data sampling period is 1-10000 data sampling points, similarly, the second effective data sampling period is 500-
In the implementation process of the embodiment, the effective data corresponding to the output signal does not need to be calculated after periodic sampling is finished, but the effective data can be output after the sampling of at least one data group is finished, so that the waiting time is reduced; in addition, compared with the traditional method, for the motor output signals with the same time length, more effective data can be obtained by the embodiment, obviously, the samples of the effective data are richer, and the obtained conclusion is more accurate; in addition, the accumulated multiplication operation is carried out in groups in the form of data groups, and the accumulated multiplication data groups are directly called for accumulation operation, so that the calculation amount of repeated data is greatly reduced, the data processing speed is improved, and the time for obtaining the motor operation parameters is shortened.
The above description is only one specific example of the present invention and should not be construed as limiting the invention in any way. It will be apparent to persons skilled in the relevant art(s) that, having the benefit of this disclosure and its principles, various modifications and changes in form and detail can be made without departing from the principles and structures of the invention, which are, however, encompassed by the appended claims.

Claims (8)

1. A system for rapidly calculating an electrical parameter of an electrical machine, comprising
An acquisition unit: the frequency detection circuit is used for obtaining an output signal of the motor, measuring the frequency of the output signal and distorting the frequency through the frequency detection circuit to obtain a frequency f; wherein the output signal comprises an output voltage and an output current;
a sampling part: sampling according to a set AD sampling rate; the AD sampling rate is set to be 500k, and the sampling number of the output signal of the motor in one period is 500 k/f;
a control unit: dividing the sampling number in each period into y parts; calculating each data to obtain a voltage data set, a current data set and a power data set; obtaining valid data corresponding to an output signal according to the n-th to (y + n-1) data sets of each type of data, wherein n is 1,2 and 3 …; wherein n represents the nth valid data period;
the frequency detection circuit comprises a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a comparator U1; the comparator U1 adopts TLV3501 integrated chip; a 7 pin of the comparator U1 is connected with a 5V power supply, and a 4 pin is grounded; the 3 pin of the comparator U1 is connected with a resistor R3, and the other end of the resistor R3 is connected with an output signal of the motor; a second pin of the comparator U1 is respectively connected with one end of a resistor R1, a resistor R2 and one end of a capacitor C2, the other ends of a capacitor C2 and a resistor R1 are grounded, and the other end of the resistor R2 is connected with a 5V power supply; an 8 pin of the comparator U1 is grounded, the 8 pin is also connected with one end of a capacitor C1, and the other end of the capacitor C1 is connected with a 5V power supply; the 1 pin and the 5 pin of the comparator U1 are both connected in an idle mode, the 6 pin is used as output, and the resistance values of the resistor R1 and the resistor R2 are equal;
voltage division is carried out through a resistor R1 and a resistor R2, and a voltage value at a pin 2 of the comparator U1 is obtained; the output signal of the motor passes through the detection circuit, if the output signal of the motor is higher than the voltage value at the pin 2 of the comparator U1, the pin 6 outputs high level, otherwise, the output signal of the motor outputs low level, the output signal of the motor is distorted through the detection circuit, the zero crossing point is shifted, and the frequency output by the pin 6 of the detection circuit is not changed.
2. A method for rapidly calculating an electrical parameter of a motor, comprising the steps of:
step 1: obtaining an output signal of the motor, measuring the frequency of the output signal, and distorting the frequency through a frequency detection circuit to obtain a frequency f; wherein the output signal comprises an output voltage and an output current;
step 2: sampling according to a set AD sampling rate; the AD sampling rate is set to be 500k, and the sampling number of the output signal of the motor in one period is 500 k/f;
and step 3: dividing the sampling number in each period into y parts;
and 4, step 4: calculating each data to obtain a voltage data set, a current data set and a power data set;
and 5: obtaining valid data corresponding to an output signal according to the n-th to (y + n-1) data sets of each type of data, wherein n is 1,2 and 3 …; where n represents the nth valid data period.
3. The method for rapidly calculating the electrical parameter of the motor according to claim 2, wherein the voltage data set UU in the step 4 is UU ADD The calculation of (d) is expressed as:
Figure FDA0003676654430000021
wherein y represents the average number of samples in each period as y; f represents the output frequency of the motor; 500k/yf represents the number of samples per unit after the number of samples in one period of the output signal of the motor is divided into y parts, U i Sample data representing a voltage;
current data set II ADD The calculation of (d) is expressed as:
Figure FDA0003676654430000022
wherein I i Sample data representing the current;
power data set PUI ADD The calculation of (d) is expressed as:
Figure FDA0003676654430000023
4. a method for fast calculation of electrical parameters of an electrical machine according to claim 3, wherein in step 5, the traditional calculation of effective voltage values is improved by combining the formula (5):
Figure FDA0003676654430000024
wherein UU ADDj Represents a jth group of voltage data; n represents the number of samples in one period, N is 500k/f, U RMS Representing the effective value of the voltage.
5. The method for rapidly calculating the electrical parameter of the motor according to claim 4, wherein in the step 5, the calculation formula of the effective value of the traditional current is improved by combining a formula (6):
Figure FDA0003676654430000025
wherein II ADDj Representing the jth group of voltage data, I RMS Representing the effective value of the current.
6. The method for rapidly calculating the electrical parameter of the motor according to claim 5, wherein in the step 5, the improvement is obtained by combining a traditional active power calculation formula (7):
Figure FDA0003676654430000026
wherein the PUI ADDj And (4) representing a jth group power data group, and P representing active power.
7. The method for rapidly calculating the electrical parameter of the motor according to claim 6, wherein in the step 5, the power factor PF of the motor is expressed as:
Figure FDA0003676654430000031
8. the method of claim 2 wherein y is 20, which means that the number of samples per cycle is 20, and the number of samples is 25 k/f.
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