CN204374310U - A kind of three-phase alternating-current supply lack detection circuit - Google Patents

Abstract

The utility model provides a kind of three-phase alternating-current supply lack detection circuit, and every phase power supply signal of three-phase alternating-current supply exports successively after Hi-pass filter, low-pass filter and shaping circuit; Described shaping circuit is provided with power phase shortage check point; By the voltage magnitude of Hi-pass filter decay three-phase circuit, by resistance in series dividing potential drop evanescent voltage amplitude, by low-pass filter circuit filtering high frequency interference, by signal transformation circuit shaping output signal, be convenient to controller compatibility and identify.This circuit structure is simple, with low cost, reliable.

Description

A three-phase AC power supply phase loss detection circuit

technical field

The utility model relates to a power supply detection circuit, in particular to a three-phase AC power supply phase loss detection circuit.

Background technique

At present, in the application of single-phase AC power supply, it is necessary to detect the lack of phase of three-phase AC power supply, which can quickly judge the failure of the power supply and play a protective role for other controls. At present, many phase loss detection and protection circuits use components such as optocouplers or comparators to detect phase loss protection. The cost is relatively high, and the power consumption may be relatively large, thereby affecting reliability.

Utility model content

The purpose of the utility model is to provide a simple and reliable three-phase AC power supply phase loss detection circuit to solve the problems of high cost and low reliability of the existing detection circuit.

In order to solve the above problems, the utility model is realized through the following solutions:

A three-phase AC power supply phase loss detection circuit, including sequentially connected high-pass filter, low-pass filter and shaping circuit; each phase power signal of the three-phase AC power supply passes through the high-pass filter, low-pass filter and shaping circuit in sequence Output; a power phase loss detection point is set on the shaping circuit.

The high-pass filter is composed of a first capacitor and a first resistor connected in series.

The high-pass filter is composed of a first capacitor and an array composed of at least two first resistors connected in series.

The low-pass filter is composed of a resistor with the lowest voltage in the array formed by the first resistor and a second capacitor connected in parallel.

The shaping circuit is composed of a bidirectional clamping diode and a resistance-capacitance filter circuit.

The phase loss detection point of the power supply is connected to the clamping point of the bidirectional clamping diode.

The resistance-capacitance filter circuit is connected to the clamping point of the bidirectional clamping diode, and is used for low-pass filtering the detection signal.

Compared with the existing scheme technology, the beneficial effects of this scheme are as follows: attenuate the voltage amplitude of the three-phase AC circuit through the high-pass filter, reduce the voltage amplitude, filter out high-frequency interference through the low-pass filter circuit, and filter out high-frequency interference through the signal shaping circuit Reshape the output signal, and the power supply phase loss detection point is set on the shaping circuit, which is convenient for the compatible identification of the controller. This circuit has simple structure, low cost and reliable operation.

Description of drawings

Fig. 1 is the structural representation of present embodiment;

Fig. 2 is a schematic circuit diagram of the solution of this embodiment.

Detailed ways

The utility model will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

In order to clearly illustrate the technical solutions in the utility model, preferred embodiments are given below and detailed descriptions are given in conjunction with the accompanying drawings.

Referring to FIG. 1 , it is a schematic structural diagram of this embodiment, including a high-pass filter, a low-pass filter, and a signal shaping circuit. The cut-off frequency of the high-pass filter is greater than the power frequency, and its function is to attenuate the power signal. Multiple resistor series arrays can further divide the voltage and attenuate the power signal. At the same time, it can improve the voltage tolerance, prevent breakdown, and improve reliability. The low-pass filter adopts a simple resistance-capacitance design, and its cut-off frequency is higher than the power frequency, which further attenuates the power signal and can filter out environmental interference and high-frequency components of the power itself. The signal shaping circuit includes a clamping circuit and a resistance-capacitance charge-discharge filter circuit. The clamping circuit can limit the signal level to prevent the voltage from exceeding the safe sampling voltage of the processor, which is safe and reliable; the resistance-capacitance filter circuit performs final filtering and shaping on the signal, which is convenient for the processor to sample.

Referring to FIG. 2 , it is a schematic diagram of the circuit of this embodiment. A, B, and C on the left side are three-phase alternating current input, and N is the negative terminal after rectifying the three-phase alternating current. Take phase A as an example (the principles of phase B and phase C are exactly the same), capacitor C1 and resistors R1, R2, R3, R4, R5 constitute a high-pass filter, whose cut-off frequency is greater than the power frequency, and R1, R2, R3, R4, The resistor series array formed by R5 is convenient for improving the voltage tolerance capability of the circuit. C4 and R5 constitute a low-pass filter, whose cutoff frequency is greater than the power supply frequency, and performs voltage-dividing filtering on the output signal of the high-pass filter, which can effectively filter out electromagnetic interference in the environment and high-frequency components of the power supply itself. B-phase high-pass filter is composed of capacitor C2 and resistors R6, R7, R8, R9, R10, C5, R10 constitute a low-pass filter; C-phase high-pass filter is composed of capacitor C3 and resistors R11, R12, R13, R14, R15 , C6, R15 form a low-pass filter.

The shaping circuit is composed of bidirectional clamping diodes D1, D2, D3 and a resistance-capacitance filter circuit. After the three-phase AC passes through the low-pass filter, it passes through the bidirectional clamping diodes D1, D2, D3 (for protection) and the resistance-capacitance at the rear end. The phase loss detection signals LP1, LP2, LP3 are generated after the filtering circuit, and the resistance-capacitance filtering circuit is composed of capacitors C7, C8, C9 and resistors connected in parallel with the capacitors C7, C8, and C9. The RC filter circuit is connected to the clamp point 3 of the bidirectional clamp diode.

For the devices described in each embodiment of the utility model, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims (7)

1. a three-phase AC power supply phase loss detection circuit is characterized in that, comprising: a high-pass filter, a low-pass filter and a shaping circuit connected successively; each phase power supply signal of the three-phase AC power passes through the high-pass filter, low-pass filter, and output after a pass filter and a shaping circuit; a power phase loss detection point is set on the shaping circuit. 2. The three-phase AC power supply phase loss detection circuit according to claim 1, characterized in that the high-pass filter is composed of a first capacitor and a first resistor connected in series. 3. The three-phase AC power supply phase loss detection circuit according to claim 1, wherein the high-pass filter is composed of a first capacitor and an array composed of at least two first resistors connected in series. 4. The three-phase AC power supply phase loss detection circuit according to claim 3, characterized in that the low-pass filter is composed of a resistor with the smallest voltage in the array formed by the first resistor and a second capacitor connected in parallel. 5. The three-phase AC power supply phase loss detection circuit according to claim 1, characterized in that the shaping circuit is composed of a bidirectional clamping diode and a resistance-capacitance filter circuit. 6. The three-phase AC power supply phase loss detection circuit according to claim 5, characterized in that, the power supply phase loss detection point is connected to the clamp point of the bidirectional clamp diode. 7. The three-phase AC power supply phase loss detection circuit according to claim 5, characterized in that: the resistance-capacitance filter circuit is connected to the clamping point of the bidirectional clamping diode, and is used for low-pass filtering the detection signal.