KR100196822B1 - Method and device for driving a digital multimeter accomplishing a function of wattmeter - Google Patents

Abstract

The present invention provides a driving apparatus and a driving method thereof for a digital dimming meter having a function of a meter having a multi-display form for displaying a measurement result as a multi-display technique as well as a function of a power meter.

The present invention is characterized by comprising two input terminals A and B connected to an AC input voltage section, connecting portions F and G connected to a load to be measured, and terminal portions X, Y, Z, and an output terminal (C, D, E); A common terminal portion 2 provided at one end of the terminal portion Y to be connected to the output terminal D of the adapter and grounding the entire circuit; A voltage attenuation driving unit 1 having a terminal unit X connected to the output terminal C of the adapter at one end and attenuating a voltage input from the terminal unit X to output an AC voltage waveform; An AC-DC converting unit 4 for receiving the AC voltage waveform attenuated and outputted from the voltage attenuating driving unit 1 and converting it into a DC voltage; An amplification unit 6 for receiving and amplifying the alternating voltage waveform attenuated and outputted from the voltage attenuation driving unit 1 at a non-inverting terminal; A current-to-voltage converter (3) having a terminal (Z) connected to the output terminal (E) of the adapter at one end and converting the current from the terminal (Z) to 20 A with respect to the voltage; An AC-DC converter 5 for converting a waveform of the AC current outputted from the current-voltage converter 3 into an effective value DC; An A / D converter 8 for converting an analog voltage output from the ac-dc converter 5 into digitized information; An amplification unit (7) for receiving and amplifying the AC signal output from the current-voltage conversion unit (3) from a non-inverting terminal; And an A / D converter 11 for converting an analog DC voltage output from the AC-DC converter 4 into digital information received, and a power coefficient measurement is controlled based on each measured measurement element A microprocessor (9) for generating a control signal; And a display driver (10) controlled by the microprocessor (9) and capable of displaying each measured measurement element in a multiplexed manner through a display.

Description

Driving device of digital multimeter with built-in power meter function and driving method thereof

FIG. 1 is a circuit block diagram of a power meter function portion that is built in a conventional digital multimeter and is capable of performing a power meter function.

FIG. 2 is a flow chart of a program for measuring power included in a micro loft in a digital multimeter having a built-in power meter function according to the present invention. FIG.

3 is a waveform diagram showing time delay of voltage and current.

FIG. 4 is a configuration diagram of an adapter used for measuring the power of a load.

DESCRIPTION OF THE REFERENCE NUMERALS

1: Voltage damping driving part 2: Common terminal part

3: current-voltage conversion unit 4: AC-DC conversion unit

6, 7: amplification unit 8, 11: A / D conversion unit

9: Microprocessor 10: Display driver

[Industrial Applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital multimeter comprising a sale chip, and more particularly, to a driving apparatus and a driving method thereof for a digital multimeter incorporating a power meter function capable of measuring power used in a predetermined load.

[Background Art and Problems]

In general, a conventional digital multimeter is capable of performing direct and ac voltage measurement, direct current / alternating current measurement, resistance value measurement, diode characteristic measurement, and frequency measurement as basic functions. Korean Patent No. 65675, filed and filed on April 28, 1990 by the present applicant, discloses a method for displaying each measurement value measured by a digital multimeter in accordance with a blinking state of a bar Built-in baffle function. However, the function capable of measuring the electric power used by a predetermined load and serving as a power meter capable of displaying the measured value is not built in the digital multimeter.

Therefore, when a predetermined electrical characteristic is to be measured, in addition to the digital multimeter, a power meter is further needed to measure the electric power. As described above, there is a problem in that, when two instruments having only a limited function are used in parallel as required, there is a problem that consumption cost for each instrument is increased, work efficiency is lowered, and there is a great inconvenience to use.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a driving apparatus of a digital multi-detector having a built-in power meter function not only to perform a function of a power meter but also to display multi- And a driving method thereof.

SUMMARY OF THE INVENTION [

According to another aspect of the present invention, there is provided an apparatus for driving a digital multimeter having a built-in power meter function, the apparatus including two input terminals connected to an AC input voltage unit, a connection unit connected to a load to be measured, An adapter having three output terminals inserted into terminal portions provided in the main body; A common terminal portion having a terminal portion connected to an output terminal of the adapter at one end and grounding the entire circuit; A voltage attenuation driving unit having a terminal connected to the output terminal of the integrator at one end, attenuating a voltage input from the terminal and outputting an AC voltage waveform; An AC-DC converting unit that receives the AC voltage waveform attenuated and outputted from the voltage attenuation driving unit and converts the waveform into a DC voltage; An amplification unit that receives the AC voltage waveform attenuated and outputted from the voltage attenuation driving unit at a non-inverting terminal and amplifies the AC voltage waveform; A current-to-voltage converter that is provided at one end with a terminal connected to the output terminal of the adapter and converts the current from the terminal to 20 A with respect to the voltage; An AC-to-DC converting unit which receives a waveform of an AC current output from the current-to-voltage converting unit and converts the waveform into an effective value DC; An A / D conversion unit that receives the analog voltage output from the ac-dc conversion unit and digitizes the received information; An amplifying unit for receiving and amplifying the AC signal output from the current-voltage converter at a non-inverting terminal; A microprocessor having an A / D converter for converting an analog DC voltage output from the AC-DC converter into a digitalized information, and controlling a power coefficient measurement based on each measured measurement element; And a display driver which is controlled by the microprocessor so that each of the measured measurement elements can be displayed in multiple through a display.

According to another aspect of the present invention, there is provided a method of driving a digital multimeter having a built-in power meter function, the method comprising: checking a measurement mode to confirm whether power measurement is selected; Measuring a voltage by an A / D converter inside the microprocessor and measuring an electric current by an external A / D converter; Determining whether the voltage state and the current state are high or low; Checking the rising / falling state of the voltage frequency, setting the 16-bit counter at the rising portion and starting counting if the rising state; Confirming the rising / falling state of the current frequency, and storing the 16-bit counter value at F (A) in the rising portion when the rising state is ascended; Storing the 16-bit counter value at F (V) in the rising portion of the voltage frequency, and stopping the 16-bit counter; Calculating a delayed angle; And calculating a cosine value to calculate a final power.

[Action]

According to the present invention configured as described above, an analog voltage and an analog current flowing into a digital multimeter driving apparatus having a watt-meter function built-in through three output terminals are measured by using an individual circuit to measure the rms value and the voltage, Using an analog integrated circuit that converts each analog value to a respective digital value and programmatically controlling the operation and operation of the microprocessor to obtain power in an integrated circuit state, It can be displayed through an indicator.

[Example]

Hereinafter, embodiments according to the present invention will be described in detail with reference to exemplary drawings.

FIG. 1 is a block diagram of an all-purpose part built in a conventional digital multimeter and capable of performing a power meter function. FIG. 4 is a configuration diagram of an adapter used for measuring power of a load. Embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, description of general functions of the digital multimeter is omitted, and only the functions of the power meter are described here.

In the adapter shown in FIG. 4, the B terminal is internally connected to the C terminal and the F terminal, the E terminal and the G terminal are externally connected through an external load, and the A terminal is internally connected to the D terminal have.

Here, the commercial power is input to the external adapter terminal F and the terminals C and D through the input terminals A and B of the adapter, and output to the external terminals F and G for measuring the external load.

When the input commercial voltage and the load current are input to the input terminals X, Y and Z mounted on the outside of the digital multimeter through the output terminal, the AC voltage flowing into the input terminal X is input to the voltage- Is attenuated through the amplifier (1), and then input to the amplifier (6). This input AC voltage is measured by the microprocessor 9 after the frequency waveform is amplified.

The alternating current flowing into the input terminal Z through the output terminal E is input to the amplifying unit 7 after being inputted through the current-voltage converting unit 3. [ This input AC current is controlled by the microprocessor 9 after the frequency waveform is amplified. Here, the output terminal (D) of the output terminals (C, D, E) of the adapter is connected to the common terminal section (2) to ground the circuit.

After the effective values of the respective AC voltages and currents are counted as described above, they are input to the AC-DC converters 4 and 5 to be converted into DC values, and then the DC current is input to the A / D converter 8 And the DC voltage is input to the A / D converter 11. The applied DC voltage and DC current are controlled by the microprocessor 9 as digitized information, and the value is displayed on the multiple liquid crystal display device through the display driver 10.

For example, if a load of 220V is applied to a digital multimeter with a built-in power meter function by an adapter, the voltage drops to a value of 1/10 by the resistors included in the voltage attenuation driver 1, 1/10 and then dropped to a voltage of 2.2V. At this time, the voltage output from the voltage attenuation driving unit 1 and the current value output from the current-voltage conversion unit 3 are AC, and the voltage and the current value are the commercial power frequency (about 50 to 60 Hz) And amplified by the respective amplification units 6 and 7 amplified by 20 msec. Thereafter, the effective value of the voltage is input to the A / D converter 11 in the microprocessor 9 through the amplifier 6 as a DC value, and the current flows through the AC- And is input to the A / D converter 8 as a DC value.

The A / D converter 11 in the microprocessor 9 generates digitized information with (2.2V / 2.56) x 256 = 220 counts by (Vin / Vref) x 256, And the measured value of the digitized information is displayed through the display driver in the multiple display method under the control of the processor.

At this time, in the display screen, the power measured by the adapter for external power measurement is the first segment, the AC current is the second segment, the AC voltage is the third segment, and the power coefficient calculated by the phase difference due to voltage and current is four Lt; RTI ID = 0.0 > segment < / RTI > In other words, it is possible to display the difference in the time delay (cosine pi: power coefficient) between the external applied signal source (AC voltage), the signal source (alternating current) by the load power source, All.

FIG. 2 is a flowchart of a program for measuring power included in a microprocessor in a digital multimeter having a built-in power meter function according to the present invention.

First, in step S1, the digital multimeter is turned on to operate the system.

In step S2, the system is initialized and the value of the internal memory is erased.

In step S3, a measurement element selection mode for selecting an element to be measured is selected to confirm the measurement mode of the system, and the function and display function of the digital multimeter corresponding thereto are performed.

In step S4, the voltage is measured using the A / D converter 11 inside the microprocessor, and the current is measured using the external A / D converter 8.

In step S5, it is checked whether the voltage state is a high state or a low state. If the voltage state is a high state, the current state is checked. If the voltage state is a low state, no power is displayed.

In step S6, it is checked whether the current state is a high state or a low state. In the high state, the voltage frequency state is checked. When the current state is low, no power is displayed.

In step S7, it is checked whether the voltage frequency is in the rising state or the falling state. In the ascending state, the internal counter is operated. In the descending state, the voltage frequency state is confirmed again.

In step S8, a 16-bit internal counter is set and a counter is started.

In step S9, it is checked whether the current frequency is in the rising state or the falling state. If the current state is the rising state, the internal counter value up to that time is stored in the current memory part F (A) of the microprocessor. Check the status.

In step S10, it is checked whether the voltage frequency is in the rising state or the falling state. If it is the rising state, the internal counter value until then is stored in the voltage memory part F (V) of the microprocessor. Check the status.

In step S11, by the counts F (A) and F (V) obtained through the above steps,

THETA = (F (A) / F (V)) x 360

To obtain a cosine value corresponding to the calculated angle.

In step S12, power (voltage = current x cosine value) is obtained based on the elements (voltage, current, and cosine value) measured so far.

In step S13, each measured element (for example, voltage, current, and cosine value) obtained is displayed, and other functions corresponding to the power function and the computer are communicated, and the count value is again cleared. At this time, if the waveform of the current and the voltage is measured again and the power is to be obtained, the process returns to step S3 again.

FIG. 3 is a waveform diagram according to a time delay of a voltage and a current. FIG. 3 shows a process of obtaining a cosine value in step S11 of the flowchart of FIG.

Here, F (V) corresponds to the whole cycle T, and F (A) corresponds to the cycle T1 or T2.

Therefore, a delayed load current having a positive value

Delay angle cosine = T1 / T x 360 < RTI ID = 0.0 >

.

Further, the preceding load current having a negative value

Delay angle (cosine) = T2 / T x 360

.

And, the power coefficient (cosine?) Is

Power factor (PF) = cosine (delay angle)

And the power is calculated accordingly.

[Effects of the Invention]

As described above, according to the present invention, in addition to the existing digital multimeter, a circuit for performing a power meter function is built in, and it is calculated and controlled by a program, and an adapter having three output terminals is added. Function can be performed. In addition to the function of a general digital multimeter, the integrated meter function for a special purpose can be functioned as one set, thereby making it possible to constitute a driving device of a digital multimeter in which a power meter function is built inexpensively and easily.

Claims (2)

(F, G) connected to the load to be measured, and terminal portions (X, Y, Z) provided in the main body of the digital multimeter are connected to the AC input voltage portion An adapter having three output terminals (C, D, E); A common terminal portion 2 provided at one end of the terminal portion Y to be connected to the output terminal D of the adapter and grounding the entire circuit; A voltage attenuation driving unit 1 having a terminal unit X connected to the output terminal C of the adapter at one end and attenuating a voltage input from the terminal unit X to output an AC voltage waveform; An AC-DC converting unit 4 for receiving the AC voltage waveform attenuated and outputted from the voltage attenuating driving unit 1 and converting it into a DC voltage; An amplification unit 6 for receiving and amplifying the alternating voltage waveform attenuated and outputted from the voltage attenuation driving unit 1 at a non-inverting terminal; A current-to-voltage converter (3) having a terminal (Z) connected to the output terminal (E) of the adapter at one end and converting the current from the terminal (Z) to 20 A with respect to the voltage; An AC-DC converter 5 for converting a waveform of the AC current outputted from the current-voltage converter 3 into an effective value DC; An A / D converter 8 for converting an analog voltage output from the ac-dc converter 5 into digitized information; An amplification unit (7) for receiving and amplifying the AC signal output from the current-voltage conversion unit (3) from a non-inverting terminal; And an A / D converter 11 for converting an analog DC voltage output from the AC-DC converter 4 into digital information received, and a power coefficient measurement is controlled based on each measured measurement element A microprocessor (9) for generating a control signal; And a display driver (10) which is controlled by the microprocessor (9) so that the measured measurement elements can be displayed in multiple through a display. The digital multimeter driving device . Checking the measurement mode to confirm whether or not the power measurement selection is permitted; Measuring a voltage by an A / D converter inside the microprocessor and measuring an electric current by an external A / D converter; Determining whether the voltage state and the current state are high or low; Checking the rising / falling state of the voltage frequency, setting the 16-bit counter at the rising portion and starting counting if the rising state; Confirming the rising / falling state of the current frequency, and storing the 16-bit counter value at F (A) in the rising portion when the rising state is ascended; Storing the 16-bit counter value at F (V) in the rising portion of the voltage frequency, and stopping the 16-bit counter; Calculating a delayed angle; Calculating a cosine value to calculate a final power; and calculating a cosine value of the digital multimeter.