CN203965514U - Digital power tester - Google Patents

Abstract

The utility model discloses a kind of digital power tester, it comprises: to detecting the output voltage of power supply and voltage transformer (VT) and the current transformer that output current is sampled; Voltage signal acquisition to the output of voltage transformer (VT) and current transformer respectively, for analog-to-digital sampling hold circuit; The analog quantity that sampling hold circuit is collected changes into the AD conversion chip of digital quantity; Power factor acquisition module, the voltage signal of voltage transformer (VT) and current transformer output, respectively through zero-crossing comparator input phase testing circuit, obtains the phase signal of one group of complementation; Single-chip microcomputer, its signal that AD conversion chip, power factor acquisition module are sent carries out data processing; Positive-negative power circuit, it provides operating voltage to the various chips in circuit.Its circuit is simple, with low cost, compact conformation, and testable data are comprehensive, are suitable for carrying, and can be widely used in the Site Detection of production and the sale of LED power supply.

Description

Digital power tester

Technical field

The utility model relates to a kind of electricity instrument, relates in particular to a kind of digital power tester of measuring power supply many kinds of parameters.

Background technology

LED electricity-saving lamp is more and more universal at present, and wherein LED driving power is the necessary component of LED light fixture, and its performance mainly shows by key parameters such as power, voltage, electric currents.The existing instrument for testing power supply power is more, but volume is larger, heavier mostly, is not easy to carry, and cannot in production and sales process, carry out Site Detection and performance displaying.In addition, current power measuring, function is comparatively single, and the data of detection mostly only limit to power, and can not record critical parameter information such as voltage, electric current and power factors, comparatively comprehensively reactor product performance.

Utility model content

For overcoming above-mentioned technical matters, the utility model aims to provide a kind of small and exquisite convenient, easy to operate, is convenient to Site Detection, and the power parameter detecting contains much information, and can comprehensively represent the digital power tester of power source performance.

For realizing above-mentioned technical purpose, the utility model by the following technical solutions: a kind of digital power tester, it comprises:

To detecting the output voltage of power supply and voltage transformer (VT) and the current transformer that output current is sampled;

Voltage signal acquisition to the output of voltage transformer (VT) and current transformer respectively, for analog-to-digital sampling hold circuit;

The analog quantity that sampling hold circuit is collected changes into the AD conversion chip of digital quantity;

Power factor acquisition module, the voltage signal of voltage transformer (VT) and current transformer output, respectively through zero-crossing comparator input phase testing circuit, obtains the phase signal of one group of complementation;

Single-chip microcomputer, its signal that AD conversion chip, power factor acquisition module are sent carries out data processing;

Positive-negative power circuit, it provides operating voltage to the various chips in circuit.

Foregoing circuit module integration is on circuit board, and circuit board is installed in the housing of digital power tester, and described housing is provided with operating key, connection terminal, power switch and display screen etc. outward.

The utlity model has following beneficial effect: it is by output voltage and the output current of voltage transformer (VT) and current transformer difference acquisition testing power supply, after sampling maintenance, A/D conversion, be sent in single-chip microcomputer, single-chip microcomputer carries out after data analysis, corresponding magnitude of voltage, current value being shown by display screen; Meanwhile, power factor acquisition module by the voltage signal of voltage transformer (VT) and current transformer output respectively through zero-crossing comparator input phase testing circuit, obtain the phase signal of one group of complementation, this phase signal can obtain power factor and power after single-chip microcomputer calculates, and shows by display screen; Thus, the utility model has been realized the multipurpose of output voltage, output current, power and the power factor (PF) of testing power supply.Its circuit is simple, with low cost, compact conformation, and testable data are comprehensive, are suitable for carrying, and can be widely used in the Site Detection of production and the sale of LED power supply.

Accompanying drawing explanation

Fig. 1 is the utility model circuit diagram.

Fig. 2 is the phase measurement waveform of phase detecting circuit output.

Embodiment

This digital power measuring comprises housing, and housing is provided with power lead, plug wire terminal, display screen, button, switch etc. outward, is provided with circuit board, transformer in housing; Power lead is connected on the input end of circuit board, and circuit board is connected with plug wire terminal simultaneously, for being connected with LED power supply.

Shown in Fig. 1, on described circuit board, be integrated with voltage transformer (VT), current transformer, sampling hold circuit, AD conversion chip, power factor acquisition module, single-chip microcomputer and positive-negative power circuit; Voltage transformer (VT), current transformer adopt the combined instrument transformer of TVA1421-01M, and it is for sampling detecting output voltage, the output current of power supply.

When the input voltage of voltage transformer (VT) is 0V-600V, corresponding output voltage is 0V-10V, input and output are linear change, the voltage signal of output is sent to AD conversion chip ADC0809 through sampling hold circuit, AD conversion chip ADC0809 carries out the voltage signal of receiving to be sent in single chip computer AT 89C51 after analog to digital conversion, single chip computer AT 89C51 carries out data analysis according to the signal of receiving, it according to the cycle of voltage signal, is the switching time (the single conversion time of the A/D conversion chip ADC0809 that the design selects is only 100us) of 20ms and A/D, calculate A/D sampling number in the one-period of signal, then input signal is sampled, calculate on sampling limit, limit, the computing formula of the voltage effective value based on discrete values algorithm is: wherein, K is sample sequence serial number, and U (K) is moment instantaneous voltage.

When the input current of current transformer is 0A-10A, corresponding output voltage is 0V-10V, input and output are linear change, the current signal of output is sent to AD conversion chip ADC0809 through sampling hold circuit, AD conversion chip ADC0809 carries out the current signal of receiving to be sent in single chip computer AT 89C51 after analog to digital conversion, single chip computer AT 89C51 carries out data analysis according to the signal of receiving, it according to the cycle of voltage signal, is the switching time of 20ms and A/D, calculate A/D sampling number in the one-period of signal, then input signal is sampled, calculate on sampling limit, limit, based on discrete values algorithm current effective value computing formula, be: wherein, K is that sample sequence serial number i (K) is moment current instantaneous value.

Power factor acquisition module mainly consists of zero-crossing comparator and phase detecting circuit, the voltage signal of voltage transformer (VT) and current transformer output, current signal is processed into square-wave signal through zero-crossing comparator respectively, input phase testing circuit, obtain the phase signal of one group of complementation, as shown in Figure 2, the pulse signal of phase detecting circuit output is not subject to the impact of input signal amplitude, the width T of output signal Q has reflected the phase differential between the voltage and current that detects power supply, it is the size of θ, the two-way square-wave signal converting to is sent into the INT0 of single chip computer AT 89C51, INT1 mouth, single chip computer AT 89C51 response interrupt routine during Mei road square-wave voltage negative edge, utilize single chip computer AT 89C51 timer function to determine the mistiming T that detects supply voltage and current zero-crossing point, because the frequency of line voltage and electric current is power frequency 50Hz(, the corresponding cycle is 20000us), and electrical angle corresponding to one-period is 360 °, therefore after T value is determined, power-factor angle θ can be calculated as follows $\begin{array}{c}T/\mathrm{\θ}=2000/360\\ \mathrm{\θ}=0.018T\end{array}$ (unit of T is us), power-factor cos θ can obtain easily.

By above-mentioned module, can obtain respectively voltage, electric current, the power factor that detects power supply, power P=Uicos θ, also can obtain easily.

Positive-negative power circuit produces positive and negative 5V and positive and negative 15V voltage, is used for to the various chip power supplies on circuit board, and its input end provides voltage by exporting the positive 15V transformer of positive 9V.

Display screen adopts LCD1602, and it controls demonstration by single chip computer AT 89C51.

Claims (3)

1. a digital power tester, is characterized in that, it comprises:

To detecting the output voltage of power supply and voltage transformer (VT) and the current transformer that output current is sampled;

Voltage signal acquisition to the output of voltage transformer (VT) and current transformer respectively, for analog-to-digital sampling hold circuit;

The analog quantity that sampling hold circuit is collected changes into the AD conversion chip of digital quantity;

Power factor acquisition module, the voltage signal of voltage transformer (VT) and current transformer output, respectively through zero-crossing comparator input phase testing circuit, obtains the phase signal of one group of complementation;

Single-chip microcomputer, its signal that AD conversion chip, power factor acquisition module are sent carries out data processing;

Positive-negative power circuit, it provides operating voltage to the various chips in circuit.

2. a kind of digital power tester according to claim 1, it is characterized in that, circuit module is integrated on circuit board, and circuit board is installed in the housing of digital power tester, and described housing is provided with operating key, connection terminal, power switch and display screen outward.

3. a kind of digital power tester according to claim 1, is characterized in that, the model of AD conversion chip is ADC0809, and single-chip microcomputer model is AT89C51, and voltage transformer (VT), current transformer adopt the combined instrument transformer of TVA1421-01M.