阅读说明：本技术 一种应用于电网产品的高效率ct取电电路 (Be applied to high efficiency CT of electric wire netting product and get electric circuit ) 是由 张胜强 王清金 朱建航 丰明刚 侯荣立 洪南 于 2020-03-28 设计创作，主要内容包括：本发明属于公开了一种应用于电网产品的高效率CT取电电路,该电路利用检测输出电压变化,控制开关控制电路的输出跃变从而控制整流开关电路的状态切换,实现对储能电容的充放电,保证输出电压在滞回电压内保持相对稳定。很好的解决了传统CT取电电路在整流桥后级进行短路控制造成的器件温升高,电路效率低等问题或采用PWM方式控制给终端和电表等电网产品所带来的EMC性能差的问题。(The invention discloses a high-efficiency CT power taking circuit applied to a power grid product, which controls the output jump of a switch control circuit by detecting the change of output voltage so as to control the state switching of a rectifier switch circuit, realize the charging and discharging of an energy storage capacitor and ensure that the output voltage is kept relatively stable in hysteresis voltage. The problems that the temperature of a device is increased and the circuit efficiency is low due to the fact that short circuit control is conducted on the rear stage of a rectifier bridge of a traditional CT electricity taking circuit or the problem that EMC performance is poor due to the fact that a PWM mode is adopted for controlling power grid products such as a terminal and an ammeter are solved well.)

1. The utility model provides a be applied to high efficiency CT of electric wire netting product and get electric circuit which characterized in that: the circuit comprises a CT input circuit, a rectifier switch circuit, a switch control circuit, an energy storage capacitor and an output circuit.

2. The high-efficiency CT power taking circuit applied to a power grid product according to claim 1, characterized in that: the switch control circuit is a hysteresis comparator consisting of a first resistor R1, a second resistor R2, a third resistor R3, an operational amplifier N1 and a voltage stabilizing diode VZ1, the first resistor R1 and the second resistor R2 are connected in series and are connected to two ends of an energy storage capacitor E1, the in-phase end of the operational amplifier N1 is connected with the upper end of the second resistor R2, the inverting end of the operational amplifier N1 is connected with a voltage stabilizing tube VZ1, and the third resistor R3 is connected between the output end and the in-phase input end of the operational amplifier N1; the rectifier switch circuit consists of a first diode VD1, a second diode VD2, a first MOS tube VT3 and a second MOS tube VT4, wherein the first diode VD1 and the second diode VD2 are used as upper tubes, and the first MOS tube VT3 and the second MOS tube VT4 are used as lower tubes; the output of the operational amplifier N1 is electrically connected to the gates of the first MOS transistor VT3 and the second MOS transistor VT4, the sources of the first MOS transistor VT3 and the second MOS transistor VT4 are connected to GND, the drain of the first MOS transistor VT3 is electrically connected to one pin of the CT and the anode of the first diode VD1, the drain of the second MOS transistor VT4 is electrically connected to the other pin of the CT and the anode of the second diode VD2, and the cathodes of the first diode VD1 and the second diode VD2 are connected to the anode of the energy storage capacitor E1.

3. The high-efficiency CT power taking circuit applied to a power grid product according to claim 1, characterized in that: the switch control circuit is realized by a hysteresis comparator or a separate IC device having the same function.

4. The high-efficiency CT power taking circuit applied to a power grid product according to claim 1, characterized in that: the rectification switch circuit utilizes a switch device to control state switching instead of traditional uncontrolled rectification, and adopts a single-phase bridge rectification circuit.

5. The high-efficiency CT power taking circuit applied to a power grid product according to claim 1, characterized in that: the switch control circuit rectifies the operating state of the switching circuit by detecting a change in the output voltage.

Technical Field

The invention belongs to the field of electric power systems, and particularly relates to a high-efficiency CT power taking circuit applied to a power grid product.

Background

The CT power taking circuit is mainly applied to a power line and can solve the problem that power cannot be supplied in other modes due to equipment. The ideal mode is to directly charge the storage battery by the induction power taking of the current transformer, or provide a working power supply for electric network products such as a terminal collector, an electric meter and the like, provide a communication power supply for wireless remote transmission communication equipment, and charge a rear-stage standby battery and an energy storage capacitor. Because of small volume and convenient installation, the current transformer induction power supply becomes a very important power taking mode in a power system.

The current CT electricity taking technology is usually designed into a transformer form, and the characteristics of the CT are also created. The current variation range is large and the secondary side output can not be opened, so the design difficulty of the transformer is large and the cost is high. And is more costly if one such transformer is required for each phase when used for multiple phases. The output voltage fluctuation range is large, output is almost not achieved when the CT current is small, and the serious heating problem caused by the fact that the magnetic saturation technology is usually adopted for limiting overhigh output voltage when the CT current is large is solved. Or a PWM control technology is used, but the PWM technology is complex, and because the PWM switching frequency is high, the EMC performance of equipment is greatly influenced, and a switching device generates heat seriously.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a high-efficiency CT power taking circuit applied to a power grid product.

The technical scheme of the invention is as follows: in order to achieve the purpose, the invention adopts the following specific technical scheme: a high-efficiency CT power taking circuit applied to a power grid product comprises a CT input circuit, a rectifier switch circuit, a switch control circuit, an energy storage capacitor and an output circuit.

The switch control circuit is a hysteresis comparator consisting of a first resistor R1, a second resistor R2, a third resistor R3, an operational amplifier N1 and a voltage stabilizing diode VZ1, the first resistor R1 and the second resistor R2 are connected in series and are connected to two ends of an energy storage capacitor E1, the in-phase end of the operational amplifier N1 is connected with the upper end of the second resistor R2, the inverting end of the operational amplifier N1 is connected with a voltage stabilizing tube VZ1, and the third resistor R3 is connected between the output end and the in-phase input end of the operational amplifier N1. The rectifier switch circuit is composed of a first diode VD1, a second diode VD2, a first MOS tube VT3 and a second MOS tube VT4, wherein the first diode VD1 and the second diode VD2 are used as upper tubes, and the first MOS tube VT3 and the second MOS tube VT4 are used as lower tubes. The output of the operational amplifier N1 is electrically connected to the gates of the first MOS transistor VT3 and the second MOS transistor VT4, the sources of the first MOS transistor VT3 and the second MOS transistor VT4 are connected to GND, the drain of the first MOS transistor VT3 is electrically connected to one pin of the CT and the anode of the first diode VD1, the drain of the second MOS transistor VT4 is electrically connected to the other pin of the CT and the anode of the second diode VD2, and the cathodes of the first diode VD1 and the second diode VD2 are connected to the anode of the energy storage capacitor E1.

The switch control circuit is realized by a hysteresis comparator or a separate IC device having the same function. The rectification switch circuit utilizes a switch device to control state switching instead of traditional uncontrolled rectification, and adopts a single-phase bridge rectification circuit. The switch control circuit rectifies the operating state of the switching circuit by detecting a change in the output voltage.

The output end of the CT input circuit is connected with a rectifier switch circuit, an energy storage capacitor and a switch control circuit for controlling the charging and discharging of the energy storage capacitor are connected with the rectifier switch circuit, and a lower tube of the rectifier switch circuit adopts a switch device of an internal integrated body diode. The first output end of the energy storage capacitor is connected with an output circuit, the output circuit is directly output from the energy storage capacitor or output after power conversion, the second output end of the energy storage capacitor is connected with a switch control circuit, the output end of the switch control circuit is connected to a rectifier switch circuit, the working state of the rectifier switch circuit is controlled, the rectifier switch circuit is switched between a rectifier state and a short circuit state, charging and discharging of the energy storage capacitor are controlled, and basic stability of rear-stage voltage is guaranteed.

The output of the switch control circuit is used to control the rectification switch circuit to switch between the rectification state and the short-circuit state by utilizing the characteristic that the secondary side of the CT can be in short circuit, and when the output voltage is lower than the threshold voltage V_OLWhen the voltage of the energy storage capacitor is increased, the switch control circuit outputs low level to enable the rectifier switch circuit to work in a rectification state, and the energy is provided for the load through the preceding stage circuit and charges the energy storage capacitor to increase the voltage of the energy storage capacitor. When the output voltage is higher than the threshold voltage V_OHWhen the switch is in use, the switch control circuit outputs high level,the rectifier switch circuit is enabled to work in a short-circuit state, energy is provided for the load through the energy storage capacitor, and therefore the voltage of the rectifier switch circuit falls back. The output voltage is ensured to be V through the feedback mechanism_OL～V_OHAnd remain substantially stable therebetween.

The invention has the beneficial effects that: and the number of used electronic components is small, and the reliability is high. The circuit short-circuit loss is reduced, the temperature rise of a device is reduced, the work is stable, the heating is small, the product cost is greatly reduced, the performance is improved, the circuit short-circuit loss reduction device is widely applied to electric power data acquisition equipment, and the efficiency is further improved.

Drawings

FIG. 1 is a block diagram of the circuit configuration of the present invention;

fig. 2 is a schematic circuit diagram of the present invention.

Detailed Description

The invention will be described in detail and fully with reference to the accompanying drawings. This is further illustrated by the following examples:

the invention provides a structural block diagram of a high-efficiency CT power taking circuit shown in figure 1, which comprises a CT input circuit, a rectifying switch circuit, a switch control circuit, an energy storage capacitor and an output circuit. The output of the CT input circuit is connected with the rectification switch circuit, and the output of the rectification switch circuit is connected with the energy storage capacitor. The input of the switch control circuit is taken from the energy storage capacitor, and the output of the switch control circuit is connected with the rectifier switch circuit and the energy storage capacitor. The output circuit can be directly output from the energy storage capacitor or be connected with the energy storage capacitor through the power supply conversion circuit.

As shown in fig. 2, the rectifier switch circuit is composed of diodes VD1, VD2 and switching tubes VT3, VT4, wherein the diodes VD1 and VD2 are used as upper tubes, and the switching tubes VT3 and VT4 are used as lower tubes. The switch control circuit is a hysteresis comparator consisting of an operational amplifier N1, a voltage regulator tube VZ1 and resistors R1, R2 and R3. Wherein the voltage regulator tube VZ1 is connected with the inverting terminal of the operational amplifier N1 to provide a reference voltage for the comparator, the in-phase terminal of the operational amplifier N1 is connected between the divider resistors R1 and R2, the feedback resistor R3 is connected between the non-in-phase input terminal and the output terminal of the operational amplifier N1, and the threshold voltage V is set_OLAnd V_OHIs determined by resistors R1, R2 and R3. The output of the operational amplifier N1 is electrically connected with the gates of the MOS tubes VT3 and VT4, the sources of the MOS tubes VT3 and VT4 are connected with GND, the drain of the MOS tube VT3 is electrically connected with one pin of the CT and the anode of the diode VD1, the drain of the MOS tube VT4 is electrically connected with the other pin of the CT and the anode of the diode VD2, and the cathodes of the diodes VD1 and VD2 are connected with the anode of the energy storage capacitor E1.

The working principle is as follows: the invention utilizes the characteristic that the secondary side of the current transformer can be in short circuit to change the working state of the rectifier switch circuit through the output jump of the switch control circuit, in particular to the rectifier switch circuit working in the rectifier state when VT3 and VT4 are turned off, the rectifier switch circuit working in the short circuit state when VT3 and VT4 are turned on, and the switch control circuit detects the change of the output voltage to control the switching of the two states. When the output voltage is lower than the threshold voltage V_OLWhen the same-phase input end of the operational amplifier is lower than the reference voltage V_refWhen the switch control circuit outputs low level, VT3 and VT4 are turned off, the rectifier switch circuit is in a rectification state, and energy is provided for a load and an energy storage capacitor is charged through a preceding CT input circuit, so that the output voltage is raised. When the output voltage is higher than the threshold voltage V_OHWhen the same-phase input end of the operational amplifier is higher than the reference voltage V_refWhen the switch control circuit outputs high level, VT3 and VT4 are conducted, the rectifier switch circuit is in short circuit state, the preceding CT input circuit is short-circuited, energy is provided for the load through the energy storage capacitor, and the output voltage falls back. The output voltage is enabled to be V through the feedback control_OL～V_OHAnd remain relatively stable.

Of course, the switch control circuit in the invention can be replaced by a voltage detection IC with similar action, and the principle is the same. Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.