Self-resetting over / under voltage protector and control method thereof

Abstract

A self-resetting over / under voltage protector includes a detection circuit, a control module and a relay, the detection circuit collects and feeds back current signal and voltage signal of a main line, the control module drives the relay according to the current signal and the voltage signal, the detection circuit includes a voltage value and phase detection circuit feeding back voltage value and phase information to the control module, the control module acquires the current zero-crossing time through the voltage value and phase detection circuit, when over / under voltage fault exists in the main line, the control module drives the contacts of the relay to open, when the main line is in normal operation state, the control module drives the contacts of the relay to close, and the closing time of the relay is within 5 ms before the current zero-crossing time; a control method of the self-resetting over / under voltage protector, the current zero-crossing time is calculated, and the closing time is within 5 ms before the current zero-crossing time. The closing time is controlled to be close to the current zero-crossing time, avoiding the current peak, which is beneficial to improve the reliability and safety of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of protecting electrical circuit, in particular to a self-resetting over / under voltage protector and a control method thereof. BACKGROUND

[0002] With the rapid development of China's economy, people's living standards are constantly improving, and the increase of household electrical equipment, the safety and continuity of electricity has become a growing problem, according to the standard JB / T12762-2015 "self-resetting over / under voltage protector" stipulates that each set of residential should be set self-resetting over / under voltage protection electrical appliances, and the standard specification without over-current protection OUPA should be carried out rated limit short-circuit current ability test. At present, the execution element of the conventional self-resetting over / under voltage protector is generally a magnetic latching relay, the N pole uses a straight-through wire, and the existing product sets a predetermined delay time for closing after the over / under voltage protector is disconnected. However, the influence of current is not considered when setting the delay closing time, so that the relay may bear a large current when closing, and the product has certain safety hazards. SUMMARY

[0003] The present application aims to overcome the defects of the prior art, and provides a self-resetting over / under voltage protector with high reliability and small current borne by the relay during the delay closing.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] A self-resetting over / under voltage protector, comprising a detection circuit connected to a main line, a control module connected to the detection circuit, and a relay connected to the control module, the detection circuit collects and feeds back the current signal and voltage signal of the main line, the control module drives the contactor of the relay to open or close according to the current signal and voltage signal fed back by the detection circuit, the detection circuit comprises a voltage value and phase detection circuit for feeding back the voltage value and phase information to the control module, the control module obtains the current zero-crossing point through the voltage value and phase detection circuit, when there is an over / under voltage fault in the main line, the control module drives the contactor of the relay to open, and when the main line is in a normal operating state, the control module drives the contactor of the relay to close, and the closing time of the relay is within 5ms of the current zero-crossing point.

[0006] Preferably, the control module calculates the delay closing time of the closing signal sent to the relay according to the selected power factor and the characteristic time of the voltage waveform, so as to obtain the closing instruction output time.

[0007] Preferably, the time delay closing time further comprises an inherent time delay of the relay, the inherent time delay being a time period between the time of outputting the closing instruction and the closing time of the relay.

[0008] Preferably, the characteristic time of the voltage waveform comprises a zero-crossing time or a peak time of the voltage value.

[0009] Preferably, the closing time of the relay and the opening time of the series short-circuit protection device are the same current zero-crossing time when the main line is in normal operation.

[0010] Preferably, the closing time of the relay and the opening time of the series short-circuit protection device are symmetrical about the current zero-crossing time.

[0011] Preferably, when the voltage value of the main line is greater than the voltage protection threshold value and lasts for a preset over / under voltage fault protection time threshold value, or when the voltage value of the main line is less than the voltage protection threshold value and lasts for a preset over / under voltage fault protection time threshold value, the control module drives the contacts of the relay to open.

[0012] Preferably, the control method further comprises an indication module connected to the control module, the indication module indicating the current state and / or issuing an alarm according to the control signal output by the control module.

[0013] Preferably, the control module makes the closing time of the relay within 3 ms before the current zero-crossing time.

[0014] A control method of a self-restoring over / under voltage protector, comprising the following steps:

[0015] Step S1: calculating a current zero-crossing time;

[0016] Step S2: controlling the relay to close within 5 ms before the current zero-crossing time according to the calculated current zero-crossing time.

[0017] Further, in step S1, first, a power factor parameter is selected according to the load characteristics, second, a characteristic time of a voltage waveform is obtained, and finally, a current zero-crossing time is calculated according to the power factor and the characteristic time.

[0018] Further, in step S2, a closing time of the relay is selected, and a time of outputting a closing instruction by the controller is calculated according to the closing time of the relay.

[0019] Further, in step S2, a time of outputting a closing instruction by the controller is calculated according to the selected closing time of the relay and an inherent time delay of the relay.

[0020] Further, in step S2, a time of 2.5 ms before the current zero-crossing time is selected as the closing time.

[0021] The self-resetting over / under voltage protector and the control method thereof, the control module acquires the current zero-crossing moment through the voltage value and phase detection circuit, and controls the closing moment of the relay to be close to the current zero-crossing moment, so that the relay can avoid the current peak, and the reliability and safety of the product are improved.

[0022] In addition, there is only one current zero-crossing moment between the closing moment of the relay and the opening moment of the short-circuit protection device (SCPD), so that the current flowing through the relay is as small as possible, and the reliability and safety of the product are further improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of a self-resetting over / under voltage protector of the present application;

[0024] Figure 2 is a schematic diagram of the principle of a self-resetting over / under voltage protector of the present application;

[0025] Figure 3 is a current waveform diagram of an embodiment of the present application;

[0026] Figure 4 is a current waveform diagram of another embodiment of the present application;

[0027] Figure 5 is a connection diagram of the over / under voltage protector and the short-circuit protection device in the present application. DETAILED DESCRIPTION

[0028] The following embodiments are given to further illustrate the specific implementation of the self-resetting over / under voltage protector and the control method thereof of the present application. The self-resetting over / under voltage protector and the control method thereof of the present application are not limited to the description of the following embodiments. Figures 1 to 5 The self-resetting over / under voltage protector comprises a detection circuit connected to a main line, a control module connected to the detection circuit, and a relay connected to the control module. The detection circuit collects and feeds back the current signal and voltage signal of the main line. The control module drives the contact of the relay to open or close according to the current signal and voltage signal fed back by the detection circuit. The detection circuit comprises a voltage value and phase detection circuit for feeding back the voltage value and phase information to the control module. The control module acquires the current zero-crossing moment through the voltage value and phase detection circuit. When there is an over / under voltage fault in the main line, the control module drives the contact of the relay to open according to the voltage value. When the main line is in a normal operating state, the control module drives the contact of the relay to close, and the closing moment of the relay is close to the current zero-crossing moment, that is, within 5 ms before the current zero-crossing moment.

[0029]

[0030] ​The self-resetting over-voltage and under-voltage protector comprises a control module, a detection circuit, an indicating module and a relay connected to the control module respectively, the detection circuit is connected between the control module and a main circuit, the detection circuit is used to collect current signals and voltage signals of the main circuit and feed back the signals to the control module in the form of signals, the control module drives the contacts of the relay to close or open by processing and judging the signals fed back by the detection circuit, at the same time, the control module outputs control signals to the indicating module, so that the indicating module indicates the current state of the protector and / or sends an alarm.

[0031] In combination Figures 1-3 An embodiment is provided, the self-resetting over-voltage and under-voltage protector comprises a control module and a detection circuit, an indicating module and a relay connected to the control module respectively, the detection circuit is connected between the control module and a main circuit, the detection circuit is used to collect current signals and voltage signals of the main circuit and feed back the signals to the control module in the form of signals, the control module drives the contacts of the relay to close or open by processing and judging the signals fed back by the detection circuit, at the same time, the control module outputs control signals to the indicating module, so that the indicating module indicates the current state of the protector and / or sends an alarm. The self-resetting over-voltage and under-voltage protector further comprises a power supply circuit module, which provides the required working power supply for the control module, the relay and the indicating module. In this embodiment, the control module comprises a controller and a peripheral circuit connected to the controller, the controller is preferably an MCU, the peripheral circuit is connected to the relay, the detection circuit and the indicating module respectively and transmits signals.

[0032] In this embodiment, the detection circuit comprises a voltage value and phase detection circuit, which feeds back voltage values and phase information of the main circuit to the control module, the control module obtains the current zero-crossing time through the voltage value and phase detection circuit, when over-voltage and under-voltage faults exist in the main circuit, the control module drives the contacts of the relay to open according to the voltage values, at the same time, the control module outputs control signals to the indicating module, so that the indicating module indicates that the protector is currently in the open state and an alarm can be sent by the indicating module, under the normal operating state of the main circuit, such as the voltage and current meet the operating requirements, the control module calculates the delay closing time of the relay according to the power factor, voltage value and phase information, so that the voltage meets the closing requirements, the control module sends a closing signal to the relay after the delay closing time, so that the closing time of the relay is close to the current zero-crossing time, that is, the closing time of the relay is within 5 ms before the current zero-crossing time. More preferably, the closing time of the relay is within 3 ms before the current zero-crossing time.

[0033] Specifically as Figure 2As shown, when the contacts of the relay are in the closed state, the control module determines according to the voltage signal fed back by the detection circuit. If the main line has an over-voltage fault, that is, when the voltage value of the main line is greater than the over-voltage protection threshold and lasts for a period of time, or when the voltage value of the main line is less than the under-voltage protection threshold and lasts for a period of time, and the duration is greater than or equal to the over-voltage and under-voltage fault protection time threshold set by the control module in advance, the control module drives the contacts of the relay to open. If the main line is in a normal operating state, the contacts of the relay remain in the closed state. When the contacts of the relay are in the open state, the control module determines according to the voltage signal fed back by the detection circuit. When the main line still has an over-voltage and under-voltage fault, the contacts of the relay remain in the open state. When the main line does not have an over-voltage and under-voltage fault, that is, the main line is in a normal operating state, the control module obtains the characteristic moment of the voltage waveform according to the power factor, and the characteristic moment is preferably the zero-crossing moment or the peak moment of the voltage value. According to the characteristic moment, the control module calculates the delay closing time according to the voltage value and the phase information to obtain the closing instruction output moment of the closing instruction sent to the relay. The control module sends a closing command at the closing instruction output moment to make the contacts of the relay complete the closing action near the current zero-crossing point, that is, the closing moment of the relay is within 5 ms before the current zero-crossing moment. At the same time, the control module outputs a control signal to make the indication module indicate the closing state.

[0034] Further, as shown in Figure 5 , the over-voltage and under-voltage protector is connected in series with the short-circuit protection device (SCPD) in the main line, and the over-voltage and under-voltage protector is cascaded below the SCPD. The SCPD acts according to its own protection characteristics and is not controlled by the over-voltage and under-voltage protector. The SCPD limits the opening time under short-circuit current to be less than 5 ms. The closing moment of the relay and the opening moment of the SCPD are the same current zero-crossing moment, that is, the contact closing duration of the relay only crosses one current zero-crossing moment (see Figure 3 ), so that the current during the period is minimized, and preferably the closing moment of the relay and the opening moment of the SCPD are symmetrical about the current zero-crossing moment, one before the current zero-crossing moment and one after the current zero-crossing moment, for example, both are 2 ms away from the current zero-crossing moment. In this way, while ensuring that the relay is not closed at the current peak, the current flowing through the relay during the contact closing period is as small as possible, further improving the reliability and safety of the product.

[0035] In addition, the relay usually has an inherent delay time, which needs to be considered when calculating the extended closing time. In this embodiment, the inherent delay time is the period of time between the output closing instruction moment and the relay closing moment.

[0036] As shown in Figure 3 , 4This section details the relay delay closing process during normal operation of the main line, using an example. Since the over / under voltage protector is in the open position, the load current phase cannot be directly obtained. However, the over / under voltage protector supplies power to the front end, making it convenient to obtain the voltage phase. Therefore, the current phase can be indirectly calculated by detecting the voltage phase. Furthermore, the phase relationship between voltage and current is related to the system load type; that is, if the system power factor is known, the phase relationship between voltage and current can be confirmed. Using this method, the control module, knowing the system power factor and detecting the voltage phase, can quickly calculate the current phase. For example, the MCU in the control module determines the voltage and current phase relationship based on the power factor. If the power factor is 1, the voltage and current are in phase, meaning the voltage zero-crossing time is the same as the current zero-crossing time. If the power factor is 0.5L, the voltage leads the current phase by 60°. The MCU in the control module can calculate that the current zero-crossing time lags the voltage zero-crossing time by approximately 3.33ms, where one period is 2π, 20ms, and 60° is approximately 1 / 6 of a period.

[0037] exist Figure 3 In the process, the over / under voltage protection system load power factor is first set to 1. After power-on, the control module calculates the current and voltage phase relationship based on the set power factor of 1, at which point the voltage and current are in phase. The zero-crossing point of the current is selected as the characteristic moment, and the inherent delay time of the relay is set to 5ms. The control relay closes 3ms before the current zero-crossing point. When the control module detects the current zero-crossing point, it calculates the current zero-crossing characteristic moment point based on the voltage value and the voltage and phase information fed back by the phase detection circuit: 20ms*n; therefore, the closing command output time is: 20ms*n-3ms-5ms. Figure 3 As shown, the control module detects the current zero-crossing point and selects the next feature point as the base point, i.e., n is 1. The current zero-crossing point is at 20ms, so the relay closing time is 17ms (20ms - 3ms). Figure 3 (marked as T2), the control module issues the closing command at 12ms (20ms-3ms-5ms).

[0038] by Figure 4 For example, let's explain in detail how to set the load power factor of an over / under voltage protection system to 0.5L. First, set the load power factor of the over / under voltage protection system to 0.5L. After power-on, the control module calculates the current-voltage phase relationship based on the set power factor of 0.5L, that is, the voltage phase leads the current by 60°, and the moment when the voltage crosses zero is the characteristic moment. Figure 4 T1) Leading current zero-crossing characteristic moment ( Figure 4, T2) is about 3.33 ms. The relay inherent delay time is 5 ms, and the relay is controlled to close at 3 ms before the current zero-crossing time. When the control module detects the voltage zero-crossing, the control module calculates the voltage zero-crossing characteristic time point according to the voltage value and the phase information fed back by the phase detection circuit: 20 ms*n; the current zero-crossing characteristic time point: 20 ms*n-3.33 ms. Then the closing instruction output time is: 20 ms*n-3.33 ms-3 ms-5 ms. As shown in Figure 4 Fig. 9, the control module detects the voltage zero-crossing and selects n=1 as the next characteristic point, the voltage zero-crossing time is 20 ms, the current zero-crossing time is 20 ms-3.3 ms, the relay closing time is 13.7 ms (20 ms-3.3 ms-3 ms), and the control module issues the closing instruction at 8.7 ms (20 ms-3.3 ms-3 ms-5 ms).

[0039] In an ideal case, the relay closing time is symmetrical about the current zero-crossing time with the SCPD disconnection time under the short-circuit limiting condition. In this embodiment, the current zero-crossing time between the relay closing time and the SCPD disconnection time is the first current zero-crossing time after the characteristic time. Of course, when the characteristic time is the current peak, the current zero-crossing time between the relay closing time and the SCPD disconnection time is the first current zero-crossing time after the characteristic time.

[0040] It should be noted that the control module can also calculate the current zero-crossing time by other algorithms, which are all within the protection scope of the present application.

[0041] A control method of a self-resetting over / under voltage protector, comprising the following steps:

[0042] Step S1: calculating the current zero-crossing time;

[0043] Step S2: controlling the relay to close within 5 ms before the current zero-crossing time according to the calculated current zero-crossing time.

[0044] The specific process is that, in step S1, first, the power factor parameter is selected and set according to the load characteristics, second, the characteristic time of the voltage waveform is obtained, and finally, the current zero-crossing time is calculated according to the power factor and the characteristic time.

[0045] In step S2, the closing time of the relay is selected, so that the closing time of the relay is located within 5 ms before the current zero-crossing time. In this embodiment, the short-circuit protection device limits the opening time under short-circuit current to be less than 5 ms, and the time of 2.5 ms before the current zero-crossing time is selected as the closing time of the relay. The time of the controller outputting the closing instruction is calculated according to the closing time of the relay, and the inherent delay time of the relay is preferably fully considered when the time of the controller outputting the closing instruction is calculated.

[0046] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific implementation of the present application should not be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be regarded as falling within the protection scope of the present application.

Claims

1. A self-resetting over / under voltage protector, comprising a detection circuit connected to the main line, a control module connected to the detection circuit, and a relay connected to the control module, wherein the detection circuit acquires and feeds back current and voltage signals of the main line, and the control module drives the contacts of the relay to open or close according to the current and voltage signals fed back by the detection circuit, characterized in that: The detection circuit comprises a voltage value and phase detection circuit for feeding back voltage value and phase information to the control module, the control module acquires the current zero-crossing time through the voltage value and phase detection circuit, when over-voltage or under-voltage fault exists in the main line, the control module drives the contacts of the relay to open, when the main line is in normal operation state, the control module drives the contacts of the relay to close, and the closing time of the relay is within 5 ms before the current zero-crossing time, the closing time of the relay and the opening time of the series short-circuit protection device are the same current zero-crossing time, the closing time of the relay is before the current zero-crossing time, and the opening time of the short-circuit protection device is after the current zero-crossing time.

2. A self-resetting over / under-voltage protector according to claim 1, characterised in that: The control module calculates the delay closing time of sending the closing signal to the relay according to the selected power factor and the characteristic time of the acquired voltage waveform, so as to obtain the closing instruction output time.

3. A self-resetting over / under-voltage protector according to claim 2, characterised in that: The delay closing time further comprises an inherent delay time of the relay, and the inherent delay time is a time period between the output closing instruction time and the closing time of the relay.

4. A self-resetting over / under-voltage protector according to claim 2, wherein: The characteristic time of the voltage waveform comprises the zero-crossing time or the peak time of the voltage value.

5. A self-resetting over / under-voltage protector according to claim 1, characterized in that: When the voltage value of the main line is greater than the voltage protection threshold value and lasts for a preset over-voltage or under-voltage fault protection time threshold value, or when the voltage value of the main line is less than the voltage protection threshold value and lasts for a preset over-voltage or under-voltage fault protection time threshold value, the control module drives the contacts of the relay to open.

6. A self-resetting over / under-voltage protector according to any one of claims 1 to 5, characterised in that: Further comprising an indication module connected with the control module, the indication module indicates the current state and / or sends an alarm according to the control signal output by the control module.

7. The self-resetting over / under-voltage protector of claim 1, wherein: The control module makes the closing time of the relay within 3 ms before the current zero-crossing time.

8. A control method of a self-resetting over- and under-voltage protector, characterized in that: The method comprises the following steps: Step S1: first, selecting and setting the power factor parameter according to the load characteristics, second, acquiring the characteristic time of the voltage waveform, and finally, calculating the current zero-crossing time according to the power factor and the characteristic time; Step S2: controlling the relay to close within 5 ms before the current zero-crossing time according to the calculated current zero-crossing time, the closing time of the relay and the opening time of the series short-circuit protection device are the same current zero-crossing time, the closing time of the relay is before the current zero-crossing time, and the opening time of the short-circuit protection device is after the current zero-crossing time.

9. The control method of the self-resetting over-voltage and under-voltage protector according to claim 8, wherein: In step S2, the closing time of the relay is selected, and the time of outputting the closing instruction by the controller is calculated according to the closing time of the relay.

10. The control method of a self-resetting over / under-voltage protector according to claim 9, characterized in that: In step S2, the time of outputting the closing instruction by the controller is calculated according to the selected closing time of the relay and the inherent delay time of the relay.

11. The control method of a self-resetting over / under-voltage protector according to claim 9 or 10, characterized in that: In step S2, the time of 2.5 ms before the current zero-crossing time is selected as the closing time.

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