CN115343526A

CN115343526A - Alternating-current undervoltage and phase detection device

Info

Publication number: CN115343526A
Application number: CN202110521290.4A
Authority: CN
Inventors: 李尉齐; 刘泰均
Original assignee: Good Will Instrument Co Ltd
Current assignee: Good Will Instrument Co Ltd
Priority date: 2021-05-13
Filing date: 2021-05-13
Publication date: 2022-11-15

Abstract

The invention relates to an alternating-current undervoltage and phase detection device which is used for detecting an alternating-current input voltage and comprises a comparator, a positive end voltage division unit, a negative end voltage division unit and an inverter unit, wherein the alternating-current input voltage is converted into a positive end half-wave voltage and a negative end half-wave voltage and then is respectively input into the positive end voltage division unit and the negative end voltage division unit; the comparator compares the voltages of the two input ends, and can judge whether the voltage value of the alternating current input voltage is normal or not by the output voltage level of the comparator and can detect the switching point of the positive/negative half cycle voltage.

Description

Alternating-current undervoltage and phase detection device

Technical Field

The present invention relates to power detection, and more particularly to an ac undervoltage and phase detection apparatus.

Background

In an ac power control system, it is necessary to strictly monitor the voltage level change and phase change of ac power, and especially when a plurality of ac voltage sources are connected in parallel for centralized power supply, it is necessary to consider whether the voltage level change and phase change of each ac power source are consistent with those of other ac power sources to be connected in parallel, and when the input voltage level is lower than a preset level, it is a so-called under-voltage problem.

For example, in the application fields of utility grid connection, solar power generation, wind power generation or various power supplies, a plurality of ac voltage sources may be connected in parallel and then become a power supply system to output power to a load, and once the voltage level or phase of any ac voltage source is not matched with that of the other ac voltage sources, the power output efficiency of the power supply system will be greatly reduced, and even the power supply system fails to output power smoothly.

Disclosure of Invention

The invention provides an alternating current undervoltage and phase detection device which is used for detecting whether an alternating current input voltage has an undervoltage problem or not, and detecting the phase change of the alternating current input voltage when the alternating current input voltage has a normal voltage.

The alternating-current undervoltage and phase detection device of the invention is used for detecting an alternating-current input voltage, the positive half-cycle voltage of the alternating-current input voltage is a positive end half-wave voltage, the negative half-cycle voltage of the alternating-current input voltage is a negative end half-wave voltage after phase inversion, and the alternating-current undervoltage and phase detection device comprises:

a comparator having a positive phase input terminal, a negative phase input terminal and an output terminal;

the positive end voltage division unit is connected with the positive phase input end of the comparator, divides the positive end half-wave voltage to generate a positive phase input voltage, and provides the positive phase input voltage for the positive phase input end of the comparator;

the negative end voltage division unit is connected with the inverting input end of the comparator and outputs a first voltage division value to the inverting input end of the comparator according to the negative end half-wave voltage and a first working voltage;

the inverter unit is connected between the inverting input end and the output end of the comparator, and outputs a second voltage division value to the inverting input end of the comparator according to a second working voltage when the inverter unit is conducted;

when the negative-end half-wave voltage is zero and the inverter unit is turned on, the first voltage division value and the second voltage division value are added to form an inverted input voltage, and the inverted input voltage has a fixed reference level.

Preferably, the positive-side voltage divider unit is formed by connecting a first resistor and a second resistor in series, and a series node of the first resistor and the second resistor is connected to the inverting input terminal of the comparator.

Preferably, the negative terminal voltage dividing unit includes:

the voltage division line comprises a third resistor and a fourth resistor which are connected in series, wherein the series node of the third resistor and the fourth resistor is connected to the inverting input end of the comparator, and one end of the fourth resistor receives the first working voltage;

and the voltage input line comprises a fifth resistor, one end of the voltage input line receives the negative end half-wave voltage, and the other end of the voltage input line is connected with the inverting input end of the comparator.

Preferably, the inverter unit comprises an inverter, the inverter is composed of a transistor, an emitter of the inverter is connected with the second working voltage, and a base of the inverter is connected to the output end of the comparator through a sixth resistor I and a voltage stabilizing diode; a seventh resistor is connected between the base and the emitter of the transistor; the collector of the transistor is connected to the inverting input terminal of the comparator through an eighth resistor.

Preferably, when the comparator outputs an output voltage of a high level, the inverted input voltage approaches a zero level.

Preferably, the second operating voltage is the same as the first operating voltage.

Preferably, the transistor is a PNP transistor.

Drawings

Fig. 1 is a detailed circuit diagram of the present invention.

Fig. 2A is a waveform diagram of a normal ac input voltage Vin.

Fig. 2B is a waveform diagram of the positive half-wave voltage VL generated according to the ac input voltage Vin.

Fig. 2C is a waveform diagram of the negative half-wave voltage VN generated according to the ac input voltage Vin.

Fig. 2D is a waveform diagram of the positive phase input voltage Vp and the negative phase input voltage Vm provided to the comparator of the present invention.

Fig. 2E is a waveform diagram of the output voltage Vo of the comparator of the present invention.

Fig. 3 is a waveform diagram of the ac input voltage Vin.

Detailed Description

The technical means adopted by the invention to achieve the predetermined object of the invention are further described below with reference to the drawings and the preferred embodiments of the invention. Each resistor shown in the circuit diagram may be formed by a single resistor or by connecting a plurality of resistors.

Fig. 1 is a detailed circuit diagram of the present invention, which mainly includes a comparator 10, a positive side voltage dividing unit 20, a negative side voltage dividing unit 30 and an inverter unit 40.

The comparator 10 has a positive input terminal, an inverted input terminal and an output terminal, and the comparator 10 may be formed by an operational amplifier, where the positive input terminal receives a positive input voltage Vp, and the inverted input terminal receives an inverted input voltage Vm.

The positive voltage dividing unit 20 is connected to the positive input terminal of the comparator 10, divides a positive half-wave voltage VL to generate the positive input voltage Vp, and provides the positive input voltage Vp to the positive input terminal of the comparator 10. The positive side voltage dividing unit 10 is composed of a plurality of resistors connected in series, in this embodiment, a first resistor R1 and a second resistor R2 are connected in series, the positive side half-wave voltage VL is connected to one end of the first resistor R1, and the non-inverting input terminal of the comparator 10 is connected to the series node of the first resistor R1 and the second resistor R2.

The negative side voltage dividing unit 30 is connected to the inverting input terminal of the comparator 10, and divides a negative side half-wave voltage VN. The negative side voltage division unit 30 includes a voltage division line and a voltage input line, wherein the voltage division line is formed by connecting a third resistor R3 and a fourth resistor R4 in series, one end of the fourth resistor R4 receives a fixed first operating voltage (for example, + 12V), one end of the third resistor R3 is grounded, and a series node of the third resistor R3 and the fourth resistor R4 is connected to the inverting input terminal of the comparator 10. In this embodiment, the voltage input line is composed of at least one fifth resistor R5, one end of the voltage input line receives the negative-side half-wave voltage VN, and the other end is connected to the inverting input terminal of the comparator 10.

The inverter unit 40 is connected between the output terminal and the inverting input terminal of the comparator 10, and includes an inverter, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a zener diode Z1. The inverter is composed of a transistor Q, the transistor Q is PNP type, an emitter of the transistor Q is connected to a second working voltage (for example + 12V), the second working voltage can be the same as or different from the first working voltage, a base of the transistor Q is connected to an output end of the comparator 10 through a sixth resistor R6 and a zener diode Z1, and a seventh resistor R7 is connected between the base and the emitter; the collector of the transistor Q is connected to the inverting input of the comparator 10 through an eighth resistor R8.

Therefore, the inverting input voltage Vm received at the inverting input terminal of the comparator 10 is determined by the negative terminal voltage dividing unit 30 and the inverter unit 40 together, and the detailed circuit is described as follows.

Referring to the waveform shown in fig. 2A, an ac input voltage Vin to be detected has a positive half-cycle voltage and a negative half-cycle voltage, and the ac input voltage Vin has a normal voltage value. The ac input voltage Vin is pre-processed by a known circuit, and then the positive half cycle voltage is extracted to become the positive half-wave voltage VL as shown in fig. 2B, and the negative half cycle voltage is inverted to become the negative half-wave voltage VN as shown in fig. 2C. The positive side half-wave voltage VL is input to the positive side voltage dividing unit 20 in fig. 1, and the negative side half-wave voltage VN is input to the negative side voltage dividing unit 30 in fig. 1.

Referring to fig. 2D, after the positive-side half-wave voltage VL passes through the positive-side voltage dividing unit 20, the positive-phase input voltage Vp can be generated, and the waveform of the positive-phase input voltage Vp is identical to that of the positive-side half-wave voltage VL but the voltage magnitude is reduced in equal proportion.

The circuit operation of the present invention can be divided into a first period T1 to a third period T3.

First period T1: first, the non-inverting input voltage Vp gradually increases from 0 level, while the inverting input voltage Vm is maintained at a reference level Vref. The second operating voltage (+ 12V) connected to the transistor Q provides a second divided voltage value to the inverting input terminal of the comparator 10 through the eighth resistor R8, and the negative terminal voltage divider 30 also provides a first divided voltage value to the inverting input terminal of the comparator 10, and the first divided voltage value and the second divided voltage value are added to obtain the inverted input voltage Vm having the reference level Vref. Since the reference level Vref is greater than the non-inverting input voltage Vp, referring to fig. 2E, the output terminal of the comparator 10 is maintained at a low output voltage Vo. Since the base of the transistor Q is low, the transistor Q is turned ON (ON). The reference level Vref is completely determined by the resistor and the fixed first and second operating voltages, regardless of the magnitude of the ac input voltage Vin. The reference level Vref is a comparative reference value for determining whether the ac input voltage Vin has an under-voltage problem.

Second period T2: the positive phase input voltage Vp is gradually increased to be greater than the reference level Vref, i.e., a second period T2 is entered. Referring to fig. 2E, at this time, the output terminal of the comparator 10 generates a high-level output voltage Vo, the transistor Q is turned OFF (OFF), and one end of the eighth resistor R8 is equivalent to an open circuit. The inverter unit 40 no longer provides the second divided voltage value, and the inverted input voltage Vm is completely determined by the negative voltage dividing unit 30, because the negative half-wave voltage VN is 0, the resistance value of the third resistor R3 connected in parallel with the fifth resistor R5 is very small, and the voltage value of the inverted input voltage Vm is very low and almost approaches to zero level.

Third period T3: after the non-inverting input voltage Vp is turned to the zero level, the third period T3 is entered. At this time, the negative half-wave voltage VN starts to be inputted to the negative voltage dividing unit 30, the inverting input terminal of the comparator 10 is provided with the variable first divided voltage value, the comparator 10 outputs the low level output voltage Vo, the transistor Q is turned to the ON (ON) state, and the inverter unit 40 provides the second divided voltage value to the inverting input terminal through the eighth resistor R8. The inverted input voltage Vm will vary synchronously with the voltage variation of the negative side half-wave voltage VN.

The rising edge of the output voltage Vo of the comparator 10 changing from low to high (i.e. T1 → T2) represents that the positive phase input voltage Vp divided from the ac input voltage Vin can be greater than the reference level Vref, confirming that the ac input voltage Vin has no under-voltage problem. On the contrary, when the brown-out problem occurs, as shown in fig. 3, the peak value of the ac input voltage Vin becomes small, the non-inverting input voltage Vp will not be greater than the reference level Vref, and the output voltage Vo of the comparator 10 is constantly maintained at the low level and will not go to the high level.

On the other hand, when the ac input voltage Vin is not under-voltage, the output voltage Vo of the comparator 10 changes from high level to low level when the ac input voltage Vin changes from positive half cycle to negative half cycle (i.e. T2 → T3), so that the time point of the phase change can be known according to the falling edge of the output voltage Vo, thereby achieving the purpose of phase detection.

In summary, the present invention can detect whether the ac input voltage Vin is under-voltage or not by using a relatively simple circuit structure, and can also determine the time point of the phase change of the positive and negative half cycles.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The utility model provides an exchange undervoltage and phase detection device for detect an exchange input voltage, exchange input voltage's positive half cycle voltage is a positive end half-wave voltage, exchange input voltage's negative half cycle voltage is a negative end half-wave voltage after the inverted phase, its characterized in that, this exchange undervoltage and phase detection device contains:

2. The apparatus of claim 1, wherein the positive voltage divider unit comprises a first resistor and a second resistor connected in series, and a series node of the first resistor and the second resistor is connected to an inverting input of the comparator.

3. The apparatus of claim 1, wherein the negative side voltage divider unit comprises:

4. The apparatus according to claim 1, wherein the inverter unit comprises an inverter, the inverter comprises a transistor, an emitter of the transistor is connected to the second operating voltage, and a base of the transistor is connected to the output terminal of the comparator through a sixth resistor I and a zener diode; a seventh resistor is connected between the base and the emitter of the transistor; the collector of the transistor is connected to the inverting input of the comparator through an eighth resistor.

5. The apparatus of claim 1, wherein the inverting input voltage provided to the comparator approaches zero when the comparator outputs a high output voltage.

6. The apparatus of claim 1, wherein the second operating voltage is substantially the same as the first operating voltage.

7. The apparatus of claim 4, wherein the transistor is a PNP transistor.