CN203012011U - Power measuring device - Google Patents

Abstract

The utility model relates to a power measuring device, which belongs to the field of electrical measurement. The utility model aims to solve the problems of application limitation and high application cost of a current/voltage transformer and a Hall current/voltage sensor for measuring power at present. The utility model includes a shunt, a voltage divider, a current signal conditioning circuit, a voltage signal conditioning circuit, a current A/D conversion circuit, a voltage A/D conversion circuit and a processor. The voltage signal output terminal of the voltage divider, the voltage signal is output to the processor through the current signal conditioning circuit and the current A/D conversion circuit; the lead wires at both ends of the voltage dividing resistor Rv of the voltage divider are the voltage signal output terminals of the voltage divider. The voltage signal is connected to the input terminal of the voltage signal conditioning circuit, and the voltage A/D conversion circuit is output to the processor; the synchronous sampling control terminal of the processor is simultaneously connected with the current sampling control terminal of the current A/D conversion circuit and the voltage A/D conversion circuit The voltage sampling control terminal is connected.

Description

power measuring device

technical field

The utility model relates to a power measuring device, which belongs to the field of electrical measurement.

Background technique

The results to be obtained by the power measurement device of the electrical measurement system are active power, reactive power, apparent power, and the phase difference between the voltage signal and the current signal. The current signal is collected by a voltage transformer or a Hall current sensor, and the voltage signal is collected by a voltage transformer or a Hall voltage sensor. However, the application of a current/voltage transformer and a Hall current/voltage sensor in an electrical measurement system has certain limitations. Limited by the frequency band, the voltage transformer can only detect the current/voltage signal in the frequency band around ±5% of the rated frequency, and the signal is a non-DC signal; the frequency band used by the Hall current/voltage sensor is 0-100kHz, although it can meet the existing electrical Measurement frequency band requirements and current control accuracy, but it is difficult to meet high-precision measurement requirements in the entire frequency band and range. And their application cost is very high.

Contents of the invention

The purpose of the utility model is to provide a power measuring device in order to solve the problems of application limitation and high application cost of current/voltage transformers and Hall current/voltage sensors for measuring power.

The power measuring device described in the utility model includes a shunt, a voltage divider, a current signal conditioning circuit, a voltage signal conditioning circuit, a current A/D conversion circuit, a voltage A/D conversion circuit and a processor,

The leads at both ends of the sampling resistor Ri of the shunt are the voltage signal output ends of the shunt, the voltage signal output end of the shunt is connected to the input end of the current signal conditioning circuit, and the output end of the current signal conditioning circuit is connected to the current A/D The analog quantity input terminal of the conversion circuit is connected, and the digital quantity output terminal of the A/D conversion circuit is connected with the current signal input terminal of the processor;

The lead wires at both ends of the voltage dividing resistor Rv of the voltage divider are the voltage signal output terminals of the voltage divider, the voltage signal output terminal of the voltage divider is connected to the input terminal of the voltage signal conditioning circuit, and the output terminal of the voltage signal conditioning circuit is connected to the input terminal of the voltage signal conditioning circuit. The analog quantity input terminal of the voltage A/D conversion circuit is connected, and the digital quantity output terminal of the voltage A/D conversion circuit is connected with the voltage signal input terminal of the processor;

The synchronous sampling control terminal of the processor is simultaneously connected with the current sampling control terminal of the current A/D conversion circuit and the voltage sampling control terminal of the voltage A/D conversion circuit.

The utility model has the advantages: the processor controls the shunt/voltage divider to obtain the voltage signal at the same time, and processes it in the background, and directly obtains the results to be used on the spot, that is, active power, reactive power, apparent power and The phase difference between the voltage signal and the current signal, so that the line voltage drop will not be caused by long-distance transmission, which ensures the high precision of the measurement. And the application cost is very low.

Description of drawings

Fig. 1 is a schematic structural diagram of the power measuring device of the present invention.

Figure 2 is a measurement schematic diagram of a shunt and a voltage divider.

Detailed ways

Specific Embodiment 1: The present embodiment will be described below in conjunction with FIG. 1 and FIG. 2. The power measurement device described in this embodiment includes a shunt 1, a voltage divider 2, a current signal conditioning circuit 3, a voltage signal conditioning circuit 4, a current A/D conversion circuit 5, voltage A/D conversion circuit 6 and processor 7,

The lead wires at both ends of the sampling resistor Ri of the shunt 1 are the voltage signal output ends of the shunt 1, the voltage signal output end of the shunt 1 is connected to the input end of the current signal conditioning circuit 3, and the output end of the current signal conditioning circuit 3 It is connected with the analog quantity input terminal of the current A/D conversion circuit 5, and the digital quantity output terminal of the A/D conversion circuit 5 is connected with the current signal input terminal of the processor 7;

The leads at both ends of the voltage dividing resistor Rv of the voltage divider 2 are the voltage signal output terminals of the voltage divider 2, and the voltage signal output terminal of the voltage divider 2 is connected to the input terminal of the voltage signal conditioning circuit 4, and the voltage signal conditioning circuit The output terminal of 4 is connected with the analog quantity input terminal of the voltage A/D conversion circuit 6, and the digital quantity output terminal of the voltage A/D conversion circuit 6 is connected with the voltage signal input terminal of the processor 7;

The synchronous sampling control terminal of the processor 7 is connected with the current sampling control terminal of the current A/D conversion circuit 5 and the voltage sampling control terminal of the voltage A/D conversion circuit 6 at the same time.

What the utility model device realizes is the measurement of power, and the measurement of power needs to collect two signals, one current signal, one is voltage signal, in this embodiment, use shunt 1 to collect current signal, use voltage divider 2 to collect voltage signal ,, See Figure 2 to illustrate its measurement principle.

The shunt 1 has a sampling resistor Ri, and the sampling resistor Ri of the shunt 1 is connected in series in the circuit to be measured. Knowing the shunt voltage u _i at both ends of the sampling resistor Ri can obtain the current i, i=u _i /Ri, sampling The voltage signal across the sampling resistor Ri is sent to the current signal conditioning circuit 3 .

All the resistances of the voltage divider 2 are R _T , which are connected in parallel in the circuit to be measured, the measured voltage at both ends of the resistance R _T is U, the voltage dividing resistance R _v is a part of the resistance R _T , and the dividing voltage at both ends of the voltage dividing resistance R _v is The voltage is _uv , and the divided voltage _uv at the two ends of the collected voltage dividing resistor _Rv is sent to the voltage signal conditioning circuit 4, _uv =U× _RT / _Rv , and the resistance value of the generally divided voltage resistor _Rv is very small, In this way, the measurement of high pressure can be realized.

The current signal and voltage signal after A/D conversion are sent to the processor 7 at the same time to obtain power.

Embodiment 2: In this embodiment, Embodiment 1 is further described, and the processor 7 is realized by a DSP digital signal processor.

Claims (2)

1. power-measuring device, it is characterized in that, it comprises shunt (1), voltage divider (2), current signal conditioning circuit (3), voltage signal conditioning circuit (4), electric current A/D change-over circuit (5), voltage A/D change-over circuit (6) and processor (7)

The sampling resistor Ri two ends extension line of shunt (1) is the voltage signal output end of shunt (1), the voltage signal output end of described shunt (1) is connected with the input end of current signal conditioning circuit (3), the output terminal of current signal conditioning circuit (3) is connected with the analog input end of electric current A/D change-over circuit (5), and the digital output end of A/D change-over circuit 5 is connected with the current signal input end of processor (7);

The divider resistance Rv two ends extension line of voltage divider (2) is the voltage signal output end of voltage divider (2), the voltage signal output end of described voltage divider (2) is connected with the input end of voltage signal conditioning circuit (4), the output terminal of voltage signal conditioning circuit (4) is connected with the analog input end of voltage A/D change-over circuit (6), and the digital output end of voltage A/D change-over circuit (6) is connected with the voltage signal input end of processor (7);

The synchronized sampling control end of processor (7) is connected with the current sample control end of electric current A/D change-over circuit (5) and the voltage sample control end of voltage A/D change-over circuit (6) simultaneously.

2. power-measuring device according to claim 1, is characterized in that, processor (7) adopts the DSP digital signal processor to realize.

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