CN212207491U

CN212207491U - Circuit structure for compensating insufficient measuring range of voltage sensor

Info

Publication number: CN212207491U
Application number: CN202020597676.4U
Authority: CN
Inventors: 李竹可; 李秋玲; 李艳伟; 梁海刚; 刘志敏
Original assignee: CRRC Xian Yonge Electric Co Ltd
Current assignee: CRRC Xian Yonge Electric Co Ltd
Priority date: 2020-04-21
Filing date: 2020-04-21
Publication date: 2020-12-22
Anticipated expiration: 2030-04-21

Abstract

The utility model belongs to the technical field of power electronic devices, and relates to a circuit structure for compensating the insufficient range of a voltage sensor, which comprises a first branch circuit and a second branch circuit which are connected in parallel, wherein the first branch circuit comprises a series resistance equivalent circuit and a Hall voltage sensor equivalent circuit which are connected in series, and the second branch circuit comprises a current transformer, an inductor and a pre-charging loop which are connected in series; the current of the whole circuit structure is divided into two paths at a node A, one path of current flows to a grounding end through a series resistance equivalent circuit and a Hall voltage sensor equivalent circuit, and the other path of current supplies power to a pre-charging loop through a current transformer and an inductor. The Hall voltage sensor is connected with the appropriate series resistor in series, the resistance value of the series resistor is adjusted to match the measurement requirements of voltages of different levels, the voltage value obtained by the voltage sensor is measured, and the voltage of the measured line can be obtained through proportion conversion, so that the voltage measurement method for measuring non-standard voltage is effectively simplified, and the voltage measurement cost is reduced.

Description

Circuit structure for compensating insufficient measuring range of voltage sensor

Technical Field

The utility model belongs to the technical field of power electronic device, a voltage sensor is related to, concretely relates to compensate circuit structure that voltage sensor range is not enough.

Background

In an electric transmission system, a voltage transformer is generally adopted to measure medium-high voltage. The existing voltage transformer is similar to a transformer and is an instrument for converting the voltage on a line. The purpose of voltage transformer transformation is to supply power to measuring instruments and relay protection devices, to measure the voltage, power and electric energy of lines, or to protect valuable equipment, motors and transformers etc. in the lines in case of line faults.

In an electric transmission system, the traditional voltage transformer has the advantages of high manufacturing precision, high cost, high manufacturing difficulty, large volume and heavy mass. The topological structure of a voltage transformer adopted in the existing railway traction system is shown in fig. 1, and as can be seen from fig. 1, the voltage transformer is converted into a signal required by a TCU control box from 25Kv/50Hz, a rear-stage circuit is very complex, a plurality of transformers need to be cascaded to convert a high-voltage signal into a low-voltage signal acceptable by the TCU control box, and the complex structure and network topology can also cause the overall measurement cost of the voltage signal to be higher.

With the development of power electronic technology, the measuring range of the hall sensor can reach the measuring range of medium voltage, the current is limited to 10mA by passing the primary voltage through an external resistor or an internal resistor by utilizing the hall effect, the magnetic field generated by the primary current is detected by the hall element in the air gap through the magnetism-gathering material after the current passes through the multi-turn winding, corresponding electromotive force is induced, the electromotive force is adjusted by a circuit and then fed back to the compensating coil for compensation, the magnetic flux generated by the compensating coil is equal in magnitude and opposite in direction to the magnetic flux generated by the primary current (the measured voltage is generated through the current-limiting resistor), and therefore the magnetic flux is kept to be zero in the magnetic core. Fig. 2 is a sampling schematic diagram of a hall voltage sensor, which can be directly connected to a sampling voltage and transmits a sampling signal to a TCU control box. However, due to the reasons of process and materials, the voltage measurement range is limited, the measurement requirements of medium and high voltage cannot be met, and few products with the range exceeding 10000V are on the market at present.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome above-mentioned prior art's shortcoming, provide one kind and compensate the not enough circuit structure of voltage sensor range to solve the unable problem that satisfies the well high-voltage measurement demand of hall voltage sensor's range.

In order to achieve the above purpose, the utility model provides a following technical scheme:

the circuit structure for compensating the insufficient measuring range of the voltage sensor comprises: the circuit comprises a first branch circuit and a second branch circuit which are connected in parallel, wherein the first branch circuit comprises a series resistance equivalent circuit and a Hall voltage sensor equivalent circuit which are connected in series, and the second branch circuit comprises a current transformer, an inductor and a pre-charging loop which are connected in series; the current of the whole circuit structure is divided into two paths at a node A, one path of current flows to a grounding end through a series resistance equivalent circuit and a Hall voltage sensor equivalent circuit, and the other path of current supplies power to a pre-charging loop through a current transformer and an inductor.

Further, a resistor R in the series resistance equivalent circuit₀And the non-inductive resistor is adopted, so that the influence of equivalent inductance on the measurement precision and the response speed is avoided.

Further, a resistor R in the series resistance equivalent circuit₀Has an accuracy of 1%, and a resistance R₀The accuracy of the resistor is determined according to actual conditions, and if the accuracy requirement is not high, the range of the series resistor can be properly amplified.

Further, a resistor R in the series resistance equivalent circuit₀Is taken to be 0.5R_TV≤R₀≤R_TVWherein R is_TVIs the resistance value of Hall voltage sensor, resistor R₀Too large, which affects the measurement accuracy of the sensor, too smallThe measurement accuracy may be affected by slight changes in the series resistance due to heat generation.

Further, a resistor R in the series resistance equivalent circuit₀The method is an integer, and can effectively avoid errors generated in the process of scaling.

Further, the input voltage value of the circuit structure is not more than twice of the rated voltage value of the Hall voltage sensor.

Further, the input voltage of the circuit structure is 6250V/50 Hz.

Compared with the prior art, the utility model provides a technical scheme includes following beneficial effect: the Hall voltage sensor is connected with the appropriate series resistor in series, the resistance value of the series resistor is adjusted to match the measurement requirements of voltages of different levels, the voltage value obtained by the voltage sensor is measured, and the voltage of the measured line can be obtained by scaling, so that the voltage measurement method for measuring non-standard voltage is effectively simplified, and the voltage measurement cost is reduced.

In addition, the resistor in the series resistor equivalent circuit adopts a non-inductive resistor, so that the influence of equivalent inductance on the measurement precision and the response speed can be avoided; the resistors in the series resistor equivalent circuit are high in precision and integer values, and errors caused in the process of proportion conversion can be avoided.

Drawings

FIG. 1 is a diagram of a topology of a conventional railway traction system employing a voltage transformer;

FIG. 2 is a sampling schematic diagram of a Hall voltage sensor;

fig. 3 is a circuit structure diagram for making up the insufficient range of the voltage sensor by using the series resistor.

Reference numerals: 1. a series resistance equivalent circuit; 2. a Hall voltage sensor equivalent circuit; 3. a pre-charge loop.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and embodiments:

example 1

Referring to fig. 3, the utility model provides a compensate circuit structure that voltage sensor range is not enough, include: the circuit comprises a first branch circuit and a second branch circuit which are connected in parallel, wherein the first branch circuit comprises a series resistance equivalent circuit 1 and a Hall voltage sensor equivalent circuit 2 which are connected in series, and the second branch circuit comprises a current transformer, an inductor and a pre-charging loop 3 which are connected in series; the current of the whole circuit structure is divided into two paths at a node A, one path of current flows to the grounding end through the series resistance equivalent circuit 1 and the Hall voltage sensor equivalent circuit 2, and the other path of current supplies power to the pre-charging loop 3 through the current transformer and the inductor.

Further, the resistance in the series resistance equivalent circuit 1 is a non-inductive resistance, i.e., L in fig. 3_oThe equivalence is 0, and the influence of equivalent inductance on the measurement precision and the response speed is avoided.

Further, the resistance accuracy in the series resistance equivalent circuit 1 is 1%, and the resistance R is₀The accuracy of the resistor is determined according to actual conditions, and if the accuracy requirement is not high, the range of the series resistor can be properly amplified.

Further, the resistance R in the series resistance equivalent circuit 1₀Is taken to be 0.5R_TV≤R₀≤R_TVWherein R is_TVIs the resistance value of the hall voltage sensor. Resistance R₀If the resistance value is too large, the measurement precision of the sensor can be influenced, and if the resistance value is too small, the series resistance value can be slightly changed due to heating to influence the measurement precision; the resistors with the resistance values being integers are selected, so that errors generated in the proportion conversion process can be effectively avoided.

Example 2

On the basis of embodiment 1, the present embodiment provides a circuit structure for making up the short measuring range of the DVL6400 type voltage sensor, and the circuit structure is to adopt a method of connecting resistors in series by using a hall voltage sensor with a rated voltage of 6400V, and matching TCU control software to convert and measure actual voltage for the input end voltage class special for the 3-unit power electronic transformer, wherein the limit peak value reaches 11000V.

The circuit structureA DVL6400 type voltage sensor of LEM company is selected, the rated voltage of the voltage sensor can be measured for 6400V, the peak value can reach 9050V, but the requirement for measuring the 11000V peak value of 3-unit power electronics cannot be met. Equivalent internal resistance R of DVL6400 type voltage sensor_TVA non-inductive resistance R of 20M omega is connected in series between external measuring voltages and is 23M omega₀And the precision is 1 percent. As known from a resistance equivalent circuit, a resistance generally has equivalent inductance, and in order to avoid the influence of equivalent series inductance on the measurement speed and precision, a non-inductive resistor is adopted in series connection, namely L is selected₀As small as possible, a non-inductive resistor, L, is selected here₀The equivalent is 0.

Referring to fig. 3, the input voltage of the whole circuit is U (voltage to be measured), and the voltage at both ends of the series resistance equivalent circuit 1 is U_RThe equivalent circuit of the voltage sensor is U_TV，R₀Is a series resistance, R_TVFor the equivalent internal resistance of the Hall voltage sensor, the specific calculation formula is as follows:

①U＝U_R+U_TV；

and combining the calculation formulas I-III, measuring the voltage value obtained by the Hall voltage sensor, and performing proportion conversion by TCU control software to obtain the voltage of the measured line. The series resistance of the voltage sensor of the power electronic transformer with 6250V input voltage is taken as an example, and the actual measurement conversion table is shown in table 1, so that the usability of the scheme is proved, and the problem that the measuring range of the voltage sensor cannot meet the requirement of medium and high voltage measurement is solved.

TABLE 1 scaling table

Further, in selecting the series resistance R₀The type selection standard and method are as follows: firstly, the series resistor should be selected to have high precision and an integral value, so that errors caused in the conversion process are avoided; secondly, the series resistor is a non-inductive resistor, so that the influence of equivalent inductance on the measurement precision and the response speed is avoided; and thirdly, the series resistor should select a proper voltage-resistant grade to avoid leakage discharge and device damage caused by over-high voltage.

To sum up, the utility model provides a this kind of compensate circuit structure that voltage sensor range is not enough, through establishing ties suitable series resistance to hall voltage sensor, the resistance through adjustment series resistance matches the measurement requirement of different grade voltages, and through the voltage value that voltage sensor measurement obtained, rethread proportion conversion can obtain the voltage of being surveyed the circuit, has simplified the voltage measurement method when measuring nonstandard voltage effectively to reduce the measurement cost of voltage.

It is to be understood that the present invention is not limited to what has been described above, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A circuit structure for compensating for a lack of range of a voltage sensor, comprising: the circuit comprises a first branch circuit and a second branch circuit which are connected in parallel, wherein the first branch circuit comprises a series resistance equivalent circuit (1) and a Hall voltage sensor equivalent circuit (2) which are connected in series, and the second branch circuit comprises a current transformer, an inductor and a pre-charging loop (3) which are connected in series; the current of the whole circuit structure is divided into two paths at a node A, one path of current flows to a grounding end through the series resistance equivalent circuit (1) and the Hall voltage sensor equivalent circuit (2), and the other path of current supplies power to the pre-charging loop (3) through the current transformer and the inductor.

2. The circuit structure for making up for the short-range voltage sensor of claim 1, wherein the resistor R in the equivalent circuit (1) of series resistors₀Non-inductive resistors are used.

3. The circuit structure for making up for the short-range voltage sensor of claim 1, wherein the resistor R in the equivalent circuit (1) of series resistors₀The accuracy of (3) is 1%.

4. The circuit structure for making up for the short-range voltage sensor of claim 1, wherein the resistor R in the equivalent circuit (1) of series resistors₀Is taken to be 0.5R_TV≤R₀≤R_TVWherein R is_TVIs the resistance value of the hall voltage sensor.

5. The circuit structure for making up for the short-range voltage sensor of claim 4, wherein the resistor R in the equivalent circuit (1) of series resistors₀Are integers.

6. The circuit structure for making up the insufficient measuring range of the voltage sensor as claimed in claim 1, wherein the input voltage value of the circuit structure is not more than twice of the rated voltage value of the hall voltage sensor.

7. The circuit structure for making up for the insufficient measurement range of the voltage sensor as claimed in claim 6, wherein the input voltage of the circuit structure is 6250V/50 Hz.