CN201113809Y - Differential Current Transformer Power Supply - Google Patents

Abstract

The utility model discloses a differential current transformer type power supply. The main body of the power supply is two sets of coils respectively wound on two annular iron cores, and the two sets of coils are differentially connected. The two AC input terminals of the bridge rectifier circuit are respectively connected to the two output terminals of the differential coil, the negative DC output terminal of the bridge rectifier circuit is grounded, and the positive DC output terminal outputs pulsating DC voltage, which is connected to the positive input of the filter circuit terminal; the positive output terminal of the filter circuit is connected to the positive input terminal of the voltage stabilizing circuit; the positive output terminal of the voltage stabilizing circuit is connected to the positive pole of the electrolytic capacitor C3, and the positive and negative poles of the electrolytic capacitor C3 are respectively used as the positive and negative output terminals of the power supply. Compared with the traditional current transformer power supply with only a single coil, under the same primary current excitation, the differential current and voltage generated by the differential coil are much smaller, so the differential current transformer power supply can be used in the primary current Keep working when it's big. The differential current transformer power supply is mainly used to supply power to the high voltage side of the electronic transformer.

Description

Differential Current Transformer Power Supply

technical field

The utility model belongs to the technical field of electric power supply, in particular to a differential current transformer type power supply, which can supply power for the high-voltage side of an electronic transformer.

Background technique

Iron-core current transformers are widely used in power systems. The core current transformer has two functions of current transformation and power supply at the same time.

In recent years, new electronic transformers (also known as air-core coil or Rogowski coil transformers) have achieved rapid development and great progress. Different from the iron core current transformer, the electronic transformer does not have the function of power supply, on the contrary, it needs to be equipped with an additional power supply to supply power for its work. Therefore, the power supply problem of the high-voltage side of the electronic transformer has been highly concerned by the power industry. At present, there are two power supply methods for the high-voltage side of the electronic transformer: 1. Laser-type power supply, 2. Iron-core current transformer-type power supply. The laser power supply works according to the principle of laser transmission and photoelectric conversion. Its disadvantages are low long-term stability, high price, small output power, and troublesome maintenance. Iron core current transformer type power supply works according to the characteristic that the iron core current transformer itself can output electric energy to the outside, without the above shortcomings of laser type power supply, so it is welcomed by people. However, there are still major problems in the iron core current transformer power supply, which is specifically manifested in that the output voltage of the power supply is easily affected by the magnitude of the primary current, resulting in unstable output voltage. For this reason, people have proposed an improved scheme using thyristor or diode shunt. This scheme can stabilize the output voltage, but it also has the problem that when the primary current is large, the core current transformer type power supply circuit will heat up seriously, making it difficult to work for a long time, so this scheme is only suitable for occasions where the primary current does not exceed 1kA . Considering that the primary rated current in the actual high-voltage line often exceeds 1kA, the application range of this solution is limited. (See literature [1] Liu Zhongzhan. Research on self-excitation source energy supply method at high voltage side of electronic current transformer. High Voltage Electrical Appliances, 2006, 42(1): 55-57; [2] Wang Haiming, Zheng Shengzhen. Electronic current transformer Research on high-voltage side power supply scheme. Power Electronics Technology, 2004, (7): 72-74)

Contents of the invention

The purpose of this utility model is to provide a differential current transformer type power supply, the power supply is still relatively low in heat generation even when the primary rated current exceeds 1kA, and can work stably for a long time in the actual circuit.

The differential current transformer type power supply provided by the utility model is characterized in that the size, structure and material of the first and second annular iron cores are the same, the first and second annular iron cores are respectively wound with first and second coils, The first and second coils together form a secondary coil, and the two are reversely connected to each other to form a differential coil;

The two AC input terminals of the bridge rectifier circuit are respectively connected to the two output terminals of the differential coil composed of the first and second coils, the negative DC output terminal of the bridge rectifier circuit is grounded, and the positive DC output terminal outputs a pulsating DC voltage. And connected to the positive input of the filter circuit;

The positive output terminal of the filter circuit is connected to the positive input terminal of the voltage stabilizing circuit, the negative input terminal and the negative output terminal of the filter circuit are grounded; the positive output terminal of the voltage stabilizing circuit is connected to the positive pole of the electrolytic capacitor C3, and the negative input terminal of the voltage stabilizing circuit The positive and negative terminals of the electrolytic capacitor C3 are used as the positive and negative output terminals of the power supply respectively.

The differential current transformer power supply of the utility model can provide reliable and stable voltage power supply for the high-voltage side of the electronic transformer, even when the primary rated current far exceeds 1kA, the heat generation is still very low, which is far lower than that of only using controllable Silicon or diode current transformer power supply, so the differential current transformer power supply can work stably for a long time in the actual circuit.

Description of drawings

Fig. 1 is a structural schematic diagram of a differential current transformer type power supply of the present invention.

Fig. 2 is a circuit block diagram of a differential current transformer power supply supplying power to the high voltage side of an electronic transformer, in which the part surrounded by a dotted line is a differential current transformer power supply.

Fig. 3 is a specific implementation diagram of a circuit of the differential current transformer type power supply of the utility model.

Detailed ways

Below in conjunction with accompanying drawing and example the utility model is described in further detail.

As shown in FIG. 1 , the structure of the differential current transformer type power supply of the utility model is as follows: the size, structure and material of the first and second annular iron cores 1 and 2 are the same. The first and second coils 3 and 4 are respectively wound on the annular cores 1 and 2. The first and second coils 3 and 4 together form a secondary coil, and the two are reversely connected to each other to form a differential coil.

The number of turns of the first coil 3 is related to many factors such as the primary current rating and output power. The actual design should be determined according to the experimental results, generally tens to hundreds of turns. The number of turns of the second coil 4 is related to the primary current The maximum value, output power and many other factors are related, and generally it can be 30% to 90% of the number of turns of the first coil 3 . The high-voltage bus passes through the ring cores 1 and 2, forming a primary coil with 1 turn on the two ring cores.

The bridge rectifier circuit 5 is used to transform the alternating differential voltage output by the first coil 3 and the second coil 4 into a DC pulsating voltage. The two AC input terminals of the bridge rectifier circuit 5 are respectively connected to the two output terminals of the differential coil composed of the first coil 3 and the second coil 4, the negative DC output terminal of the bridge rectifier circuit 5 is grounded, and the positive DC output terminal Connect to the positive input terminal of the filter circuit 6.

The positive output terminal of the filter circuit 6 is connected to the positive input terminal of the voltage stabilizing circuit 7, and both the negative input terminal and the negative output terminal of the filter circuit 6 are grounded. The positive output terminal of the voltage stabilizing circuit 7 is connected to the positive pole of the electrolytic capacitor C3, and the negative input terminal and the negative output terminal of the voltage stabilizing circuit 7 are both grounded. The negative electrode of the electrolytic capacitor C3 is grounded. The function of the voltage stabilizing circuit 7 is to change the DC voltage with a large variation range into a DC voltage with a small variation range. The positive and negative poles of the electrolytic capacitor C3 are used as the positive and negative output terminals of the power supply, which can output a stable DC voltage Vo with a small variation range.

The working process of the utility model power supply is as follows:

When the primary current Ip flows on the high-voltage bus, the differential coil composed of the first coil 3 and the second coil 4 jointly outputs alternating differential current and voltage, and the differential voltage is rectified by the bridge rectifier circuit 5 and filtered by the filter circuit 6 Afterwards, it is converted into a DC voltage whose voltage value changes with the primary current, and then converted into a stable DC voltage Vo by the voltage stabilizing circuit 7 and C3. Vo is the output of the differential current transformer type power supply.

Compared with the traditional core current transformer with only a single secondary coil, under the same primary current Ip excitation, the alternating differential current and voltage generated by the differential coil are much smaller than the alternating current and voltage of a single coil. For the same bridge rectifier circuit output voltage value, the value of Ip required when the first coil 3 and the second coil 4 form a differential coil to work is much larger than when a single first coil 3 or a single second coil 4 works alone many. For example, when the first coil 3 has 100 turns and the second coil 4 has 55 turns, when the output voltage of the bridge rectifier circuit is 26V, the Ip corresponding to the first coil 3 working alone is 0.4kA, and the first coil 3, The Ip corresponding to the operation of the differential coil composed of the second coil 4 is 1.6 kA. Therefore, even if the Ip value is large, the differential current transformer power supply can still work normally for a long time, and output stable voltage and power. Here, the allowable range of Ip variation can reach thousands of amperes, and the specific value is related to factors such as the number of turns of the first coil 3 and the second coil 4 . The input DC voltage range of the voltage stabilizing circuit 7 in the utility model is 9-30V, and the rated value of the output DC voltage can be selected among 6V, 8V, 10V, 12V, 15V, 18V, etc., and can be selected according to specific requirements during actual design Choose one of them as the power supply output DC voltage rating.

The connection relationship between the differential current transformer power supply of the utility model and the high voltage side of the electronic transformer is shown in Fig. 2 . The electronic transformer sensing device 8 converts the collected primary current Ip on the high-voltage bus into a weak current signal and sends it to the electronic transformer high-voltage side signal conditioning and data processing circuit 9, and the electronic transformer high-voltage side signal conditioning and data processing The circuit 9 converts the weak electric signal into a digital signal, and sends it to the low-voltage side part 10 of the electronic transformer through an optical fiber. The output voltage terminal of the differential current transformer power supply 11 installed on the high voltage side of the electronic transformer is connected to the power supply terminal of the signal conditioning and data processing circuit 9 on the high voltage side of the electronic transformer, which is the high voltage side signal of the electronic transformer Conditioning, data processing circuit 9 supplies power. Even if the Ip value on the high-voltage bus to be tested is large, the differential current transformer power supply can ensure the normal operation of the high-voltage side of the electronic transformer, and at the same time, due to the difference between the differential current transformer power supply and the low-voltage side of the electronic transformer. The connection also ensures the electrical insulation between the high and low voltage sides of the electronic transformer.

Example:

Assuming the Ip rated value of the primary current is 1.5kA, it is required that when the primary current varies from 0.15kA to 1.8kA, the differential current transformer power supply can output a stable 8V DC voltage and a maximum current of no more than 80mA.

The filter circuit 6 adopts a π-shaped filter circuit composed of the electrolytic capacitor C1, the inductor L, and the electrolytic capacitor C2. Both ends of the inductor L are respectively connected to the positive poles of the electrolytic capacitors C1 and C2. The negative poles of the electrolytic capacitors C1 and C2 are connected and grounded. The positive pole of the electrolytic capacitor C1 is connected to the positive DC output terminal of the bridge rectifier circuit 5 , and the positive pole of the electrolytic capacitor C2 is connected to the positive input terminal of the voltage stabilizing circuit 7 .

The parameters of each component of the differential current transformer power supply are as follows: the first coil 3 = 100 turns, the second coil 4 = 55 turns; the outer diameter of the first iron core 1 and the second iron core 2 are both 190mm, and the inner diameter is 170mm, The cross-sectional area is ^200mm2 ; the bridge rectifier circuit 5 has a current of 10A and a withstand voltage of 400V; capacitors C1 and C2 are electrolytic capacitors of 1000μf/100V; inductance L=3mH; A linear voltage regulator circuit with a current up to 1A, such as a linear three-terminal voltage regulator 7808; capacitor C3 = 2200μf/25V.

The actual measurement shows that when the primary current Ip changes from 0.15kA to 1.8kA, the output terminal voltage Vo remains about 8V, and at the same time, the maximum output current does not exceed 80mA. Meet the above pre-set requirements.

Claims (3)

1, a kind of differential current mutual-inductor type power supply, it is characterized in that: size, structure and the material of first, second ring-shaped core (1,2) are identical, be wound with first, second coil (3,4) on first, second ring-shaped core (1,2) respectively, first, second coil (3,4) constitutes secondary coil jointly, differential coil is formed in the two mutual reversal connection;

Two outputs of the differential coil that two ac input ends of bridge rectifier (5) are formed with first, second coil (3,4) respectively link to each other, the negative dc output end ground connection of bridge rectifier (5), positive direct-current output output ripple direct voltage, and the positive input terminal of access filter circuit (6);

The positive input terminal of the positive output termination voltage stabilizing circuit (7) of filter circuit (6), the negative input end of filter circuit (6) and the equal ground connection of negative output terminal; The positive output end of voltage stabilizing circuit (7) links to each other with the positive pole of electrochemical capacitor C3, the negative input end of voltage stabilizing circuit (7) and the equal ground connection of negative output terminal, and the minus earth of electrochemical capacitor C3, the positive and negative electrode of electrochemical capacitor C3 are respectively as the positive and negative output of power supply.

2, differential current mutual-inductor type power supply according to claim 1 is characterized in that: the number of turn of second coil (4) be first coil (3) the number of turn 30% to 90%.

3, differential current mutual-inductor type power supply according to claim 1 and 2, it is characterized in that: the π shape filter circuit of filter circuit (6) for constituting by electrochemical capacitor C1, inductance L, electrochemical capacitor C2, the two ends of inductance L link to each other with the positive pole of electrochemical capacitor C1, C2 respectively, the negative pole of electrochemical capacitor C1, C2 links to each other, and ground connection, the positive pole of electrochemical capacitor C1 connects the positive direct-current output of bridge rectifier (5), and the positive pole of electrochemical capacitor C2 connects the positive input terminal of voltage stabilizing circuit (7).

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