A direct current low voltage pump current detection method

Abstract

The application belongs to the technical field of water pumps, and particularly relates to a direct-current low-pressure pump current detection method, which comprises the following steps: S1, initializing a single-chip microcomputer, setting a constant A, a cache area length N, and a rated rotating speed value S0; S2, processing other processes; S3, sampling a current, removing the oldest data in the cache area, and placing the latest current value into the cache area; S4, measuring a current output rotating speed S i , and calculating a window size W according to a formula W=A+N*(1-S i / S0); S5, searching for a maximum value and a minimum value of W latest current value data, and accumulating the maximum value and the minimum value; S6, subtracting the maximum value and the minimum value from the accumulated value in the step S5; S7, obtaining a current value by taking an average, and returning to the step S2. The application can accurately and as quickly as possible obtain the current value.

Description

Technical fields:

[0001] This invention belongs to the field of water pump technology, specifically a method for detecting the current of a DC low-pressure pump. Background technology:

[0002] In DC low-voltage pump applications, the accuracy of current detection directly affects the pump's driving performance and its overall performance and efficiency. Therefore, it is necessary to obtain the current as accurately as possible. Summary of the Invention:

[0003] The purpose of this invention is to provide a method for detecting the current of a DC low-voltage pump, which can obtain the current value accurately and as quickly as possible.

[0004] This invention is implemented as follows:

[0005] A method for detecting the current of a DC low-voltage pump includes the following steps:

[0006] S1. Initialize the microcontroller, set constant A, buffer length N, and rated speed value S0;

[0007] S2, handle other processes;

[0008] S3. Sample the current, remove the oldest data from the buffer, and put the latest current value into the buffer.

[0009] S4. Measure the current output speed S i And according to the formula W=A+N*(1-S) i / S0), calculate the window size W;

[0010] S5. Retrieve the maximum and minimum values ​​of the W latest current data and sum them up;

[0011] S6. Subtract the maximum and minimum values ​​from the accumulated value in step S5;

[0012] S7. Obtain the current current value by averaging, and return to step S2.

[0013] In the aforementioned DC low-voltage pump current detection method, in step S4, when the current output speed S... i When the speed is greater than the rated speed value S0, the rated speed value S0 is assigned to the current output speed S. i Perform the calculation.

[0014] In the above-mentioned DC low-voltage pump current detection method, in step S4, when the calculated window size W is greater than the buffer length N, the buffer length N is assigned to the window size W.

[0015] In the above-mentioned DC low-voltage pump current detection method, in step S3, the current is sampled by resistor R1, filtered by resistor R2 and capacitor C1 and then sent to the microcontroller, and converted by ADC (analog-to-digital converter) to form the current value.

[0016] In the above-mentioned DC low-voltage pump current detection method, in step S3, the current filtered by resistor R2 and capacitor C1 is then sent to the microcontroller after being amplified by an operational amplifier.

[0017] In the aforementioned DC low-voltage pump current detection method, in step S4, the current output speed S i It can be read by a frequency converter board or measured by a Hall sensor connected to a DC low-voltage pump motor.

[0018] In the above-mentioned DC low-voltage pump current detection method, in step S4, the value calculated according to the formula needs to be an integer.

[0019] In the aforementioned method for detecting the current of a DC low-voltage pump, the window size W can be rounded to an integer value by rounding the calculated value, discarding the decimal places of the calculated value, or discarding the decimal places of the calculated value and then adding 1 to the integer value of the calculated value.

[0020] The outstanding advantages of this invention compared to the prior art are:

[0021] The current sampled in this invention is stored in a buffer in sequence, and the size of the current processing window is determined according to the current output speed. The larger the deviation between the current output speed and the rated speed, the larger the window size, the more current is involved in the calculation, and the more accurate the current value obtained by averaging. The smaller the deviation between the current output speed and the rated speed, the smaller the window size, the less current is involved in the calculation, and the more quickly the required current value can be obtained. In other words, the response is fast. This invention can obtain the current value accurately and as quickly as possible. Attached image description:

[0022] Figure 1 This is the control flowchart of the present invention;

[0023] Figure 2 This is the circuit schematic diagram of the present invention. Detailed implementation method:

[0024] The present invention will be further described below with reference to specific embodiments. See also: Figure 1 —2:

[0025] A method for detecting the current of a DC low-voltage pump includes the following steps:

[0026] S1. Initialize the microcontroller, set constant A, buffer length N, and rated speed value S0;

[0027] S2, handle other processes;

[0028] S3. Sample the current, remove the oldest data from the buffer, and put the latest current value into the buffer.

[0029] S4. Measure the current output speed S i And according to the formula W=A+N*(1-S) i / S0), calculate the window size W;

[0030] S5. Retrieve the maximum and minimum values ​​of the W latest current data and sum them up;

[0031] S6. Subtract the maximum and minimum values ​​from the accumulated value in step S5;

[0032] S7. Obtain the current current value by averaging, and return to step S2.

[0033] When taking the average, the dividend is the accumulated value, and the divisor is W-2, which is the final number of data points participating in the accumulation.

[0034] like Figure 1 As shown, the sampled currents of this invention are stored in the buffer in sequence, and the current is adjusted according to the current output rotational speed S. i Determine the current processing window size W, when the current output speed S i The greater the deviation from the rated speed S0, the larger the window size W, the more current is involved in the calculation, and thus the more accurate the current value obtained by averaging. When the current output speed S... i The smaller the deviation from the rated speed S0, the smaller the window size W, and the less current is involved in the calculation, resulting in a faster acquisition of the required current value, i.e., a rapid response. This invention can accurately and as quickly as possible obtain the current value.

[0035] Numerical filtering uses the method of removing extrema, accumulating and averaging, which results in accurate numerical calculations that are unaffected by maximum and minimum values.

[0036] The constant A represents a fixed number of values ​​involved in the calculation. In this embodiment, the constant A is 5.

[0037] In this embodiment, the buffer length N is 20.

[0038] The hardware circuit used in this invention is the same as that of a conventional frequency converter driver. The microcontroller is an existing microcontroller. In this embodiment, the microcontroller is ES32h0283.

[0039] Since the DC low-pressure pump itself limits the speed from exceeding the rated speed, and even if it does exceed it, the increase is minimal, resulting in a negligible impact on the current, there is no need to change the window size W. In step S4, when the current output speed S...i When the speed is greater than the rated speed value S0, the rated speed value S0 is assigned to the current output speed S. i Perform the calculation.

[0040] Furthermore, in step S4, when the calculated window size W is greater than the buffer length N, the buffer length N is assigned to the window size W.

[0041] Current sampling method: In step S3, resistor R1 is used to sample the current, which is then filtered by resistor R2 and capacitor C1 before being sent to the microcontroller. The sampled value is then converted by the ADC (analog-to-digital converter) to form the current value. The circuit principle is as follows: Figure 2 As shown.

[0042] Preferably, in step S3, the current filtered by resistor R2 and capacitor C1 is then sent to the microcontroller after being amplified by an operational amplifier.

[0043] Current output speed S i Measurement method: In step S4, the current output rotational speed S i The speed is obtained by reading from the frequency converter board or by measuring it through a Hall sensor connected to the DC low-voltage pump motor. In this embodiment, the current output speed S i Read via the frequency converter board.

[0044] Furthermore, in step S4, the value calculated according to the formula needs to be an integer.

[0045] The window size W can be rounded to an integer value by rounding the calculated value, discarding the decimal places, or discarding the decimal places and then adding 1 to the integer value. In this embodiment, the window size W is rounded to an integer value by discarding the decimal places.

[0046] The above embodiments are merely one of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, all equivalent changes made in accordance with the shape, structure and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting the current of a DC low-voltage pump, characterized in that: Includes the following steps: S1. Initialize the microcontroller, set constant A, buffer length N, and rated speed value S0; S2, handle other processes; S3. Sample the current, remove the oldest data from the buffer, and put the latest current value into the buffer. S4. Measure the current output speed S i And according to the formula W=A+N*(1-S) i / S0), calculate the window size W; S5. Retrieve the maximum and minimum values ​​of the W latest current data and sum them up; S6. Subtract the maximum and minimum values ​​from the accumulated value in step S5; S7. Obtain the current current value by averaging, and return to step S2.

2. The DC low-voltage pump current detection method according to claim 1, characterized in that: In step S4, when the current output speed S i When the speed is greater than the rated speed value S0, the rated speed value S0 is assigned to the current output speed S. i Perform the calculation.

3. The DC low-voltage pump current detection method according to claim 1, characterized in that: In step S4, when the calculated window size W is greater than the buffer length N, the buffer length N is assigned to the window size W.

4. The DC low-voltage pump current detection method according to claim 1, characterized in that: In step S3, the current is sampled using resistor R1, filtered by resistor R2 and capacitor C1, and then sent to the microcontroller. After conversion by ADC, the current value is generated.

5. The DC low-voltage pump current detection method according to claim 4, characterized in that: In step S3, the current filtered by resistor R2 and capacitor C1 is then sent to the microcontroller after being amplified by an operational amplifier.

6. The DC low-voltage pump current detection method according to claim 1, characterized in that: In step S4, the current output rotational speed S i It can be read by a frequency converter board or detected by a Hall sensor connected to a DC low-voltage pump motor.

7. The DC low-voltage pump current detection method according to claim 1, characterized in that: In step S4, the value calculated according to the formula needs to be an integer.

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