CN211697950U

CN211697950U - Current detection circuit shared by different alternating current loads

Info

Publication number: CN211697950U
Application number: CN201922496247.8U
Authority: CN
Inventors: 田宝军; 安飞虎; 李欣
Original assignee: Shenzhen F&r Technologies Co ltd
Current assignee: Shenzhen F&r Technologies Co ltd
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-10-16
Anticipated expiration: 2029-12-31

Abstract

The utility model discloses a different alternating current load sharing current detection circuitry, include: the main control module is sequentially connected with the load driving module, the current detection module, the rectification filtering module and the voltage detection unit, and the voltage detection module is connected with the main control module. The utility model discloses can realize reduce cost and reduce occupation space's beneficial effect.

Description

Current detection circuit shared by different alternating current loads

Technical Field

The utility model belongs to the technical field of the detection technique and specifically relates to a different alternating current load sharing current detection circuit is related to.

Background

With the development of the technology, household appliances with two different types of alternating current loads, such as an air purifier or an air sterilizer with an alternating current fan and an ultraviolet sterilizing lamp, an electric heater with a heating and alternating current blowing fan and the like, some medium-high-end machines require open-circuit and short-circuit fault detection and alarm functions, and a load current detection circuit is required to judge whether the load works normally.

At present, most of electric appliance products on the market adopt a current transformer or a sampling resistor to detect the current change of an alternating current load, and for application occasions requiring safe electrical isolation between a low-voltage part circuit such as a master control and a high-voltage alternating current circuit, if different types of alternating current loads need to work simultaneously, different current transformers can only be adopted to carry out electrical isolation, load current sampling detection and fault identification on different alternating current loads, because two or more current transformers are required to carry out independent detection and identification on different alternating current loads, the cost is higher, and the space occupied by a circuit board is larger. How to utilize the same set of current transformer and detection circuit thereof to realize the fault detection of different types of alternating current loads has great significance in reducing cost and improving product competitiveness.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. Therefore, the utility model provides a different alternating current load sharing current detection circuit can utilize same current detection circuit to realize the detection to the fault type of two kinds of different grade type alternating current loads, helps reducing the cost of product and reduces occupation space.

An embodiment of the utility model provides a different alternating current load sharing current detection circuit, include: the main control module is sequentially connected with the load driving module, the current detection module, the rectification filtering module and the voltage detection unit, and the voltage detection module is connected with the main control module.

The utility model discloses different alternating current load sharing current detection circuitry has following beneficial effect at least: the cost and the occupied space can be reduced.

According to another embodiment of the present invention, the load driving module comprises a first relay, a second relay, a first diode, a second diode, a first triode, a second triode, a first resistor, a second resistor, a first socket, and a second socket, wherein the first end of the first relay is connected to the first end of the first diode, the second end of the first relay is connected to the second end of the first diode, the second end of the first relay is further connected to a power supply, the collector of the first triode is connected to the first end of the first relay, the emitter of the first triode is grounded, the base of the first triode is connected to the first end of the first resistor, the second end of the first resistor is connected to the main control module, the first end of the first socket is connected to the third end of the first relay, the fourth end of first relay output connects current detection module, first socket second end is connected the zero line, the first end of second relay is connected the first end of second diode, the second end of second relay is connected the second end of second diode, the second end of second relay still connects the power, the collecting electrode of second triode is connected the first end of second relay, the projecting pole ground connection of second triode, the base of second triode is connected the first end of second resistance, the second end of second resistance is connected main control module, the first end of second socket is connected the third end of second relay output, the fourth end of second relay output connects current detection module, second socket second end is connected the zero line.

According to the utility model discloses a different alternating current load sharing current detection circuit of other embodiments, current detection module includes current transformer, third resistance, the first end of current transformer is connected the first end of third resistance, the current transformer second end is connected the third resistance second end, the current transformer third end is connected load drive module, the live wire is connected to the current transformer fourth end.

According to the utility model discloses a different alternating current load sharing current detection circuitry of other embodiments, rectification filter module includes third diode, first electric capacity, the first end of third diode is connected the first end of third resistance, the second end of third diode is connected the first end of first electric capacity, the second end ground connection of first electric capacity.

According to the utility model discloses a different alternating current load sharing current detection circuit of other embodiments, voltage detection module includes fourth resistance, fifth resistance, second electric capacity, the first end of fourth resistance is connected third diode second end, fourth resistance second end is connected the first end of fifth resistance, fifth resistance second end ground connection, the first end of fifth resistance still is connected the first end of second electric capacity, the first end of second electric capacity still is connected host system, the second electric capacity second end is connected the fifth resistance second end.

Drawings

Fig. 1 is a block diagram of a current detection circuit shared by different ac loads according to an embodiment of the present invention;

fig. 2 is a schematic circuit diagram of an embodiment of the current detection circuit for different ac loads.

Detailed Description

A/D: analog to Digital, Analog to Digital conversion.

The conception and the resulting technical effects of the present invention will be described clearly and completely with reference to the following embodiments, so that the objects, features and effects of the present invention can be fully understood. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive labor based on the embodiments of the present invention all belong to the protection scope of the present invention.

In the description of the present invention, if an orientation description is referred to, for example, the directions or positional relationships indicated by "upper", "lower", "front", "rear", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, only for convenience of description and simplification of description, and it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. If a feature is referred to as being "disposed," "secured," "connected," or "mounted" to another feature, it can be directly disposed, secured, or connected to the other feature or indirectly disposed, secured, connected, or mounted to the other feature.

In the description of the embodiments of the present invention, if "a plurality" is referred to, it means one or more, if "a plurality" is referred to, it means two or more, if "greater than", "less than" or "more than" is referred to, it is understood that the number is not included, and if "more than", "less than" or "within" is referred to, it is understood that the number is included. If reference is made to "first" or "second", this should be understood to distinguish between features and not to indicate or imply relative importance or to implicitly indicate the number of indicated features or to implicitly indicate the precedence of the indicated features.

Example 1: referring to fig. 1, a block diagram of a current detection circuit shared by different ac loads according to an embodiment of the present invention is shown. The method comprises the following steps: the device comprises a main control module, a load driving module, a current detection module, a rectification filter module and a voltage detection module, wherein the main control module is sequentially connected with the load driving module, the current detection module, the rectification filter module and a voltage detection unit, and the voltage detection module is connected with the main control module.

Example 2: referring to fig. 2, a schematic circuit diagram of an embodiment of the current detection circuit for different ac loads is shown. On the basis of embodiment 1, the load driving module selected in this embodiment includes a first relay RY1, a second relay RY2, a first diode D1, a second diode D2, a first triode Q1, a second triode Q2, a first resistor R1, a second resistor R2, a first socket CN1, and a second socket CN2, wherein a first end of the first relay RY1 is connected to the first end of the first diode D1, a second end of the first relay RY1 is connected to a second end of the first diode D1, a second end of the first relay RY1 is further connected to a power supply, a collector of the first triode Q1 is connected to the first end of the first relay 1, an emitter of the first triode RY Q1 is grounded, a base of the first triode Q1 is connected to a first end of the first resistor R1, a second end of the first resistor R1 is connected to the main control module, a first end of the first socket CN1 is connected to a first RY1, and a first terminal of the first relay CN1 is connected to the first terminal 1, the second end of the first socket CN1 is connected to the neutral line AC _ N. The first end of the second relay RY1 is connected with the first end of the second diode D2, the second end of the second relay RY2 is connected with the second end of the second diode D2, the second end of the second relay RY2 is also connected with a power supply VCC, the collector of the second triode Q2 is connected with the first end of the second relay RY2, the emitter of the second triode Q2 is grounded, the base of the second triode Q2 is connected with the first end of the second resistor R2, the second end of the second resistor R2 is connected with the main control module, the first end of the second socket CN2 is connected with the third end of the output of the second relay RY2, the fourth end of the output of the second relay 2 is connected with the current detection module, and the second end of the second socket CN2 is connected with the zero line AC _ N.

Specifically, when the pin RLY1 of the main control module outputs a high level or a low level, a signal flows through the first resistor R1 to drive the on and off of the first triode Q1 and the first relay RY 1; the pin RLY2 of the master control module outputs high level or low level, and flows through the second resistor R2 to drive the second triode Q2 and the second relay RY2 to open and close. When the first relay RY1 is pulled in and switched on, a signal passes through a primary coil of an alternating current live wire end AC _ L, the primary coil of the current transformer L1, the first relay RY1 and an alternating current load connected to the first socket CN1 to return to a zero line AC _ N end of the alternating current, and at the moment, an alternating current load connected to the first socket CN1 is electrified to work; when the second relay RY2 is pulled to be turned on, a signal passes through a live wire end AC _ L of alternating current to be connected with a primary coil of a current transformer L1, the relay RY2 and an alternating current load connected to the second socket CN2 to return to a zero line AC _ N end of the alternating current, and an alternating current load connected to the second socket CN2 is electrified to work. The first diode D1 and the second diode D2 are freewheeling diodes of the first relay RY1 and the second relay RY2, and prevent self-inductance high voltage generated by pull-in coils of the first relay RY1 and the second relay RY2 from breaking down the first triode Q1 and the second triode Q2 when the first triode Q1 and the second triode Q2 are cut off.

More specifically, when two different types of ac loads need to operate simultaneously, a method of time-sharing turning on the load and time-sharing detection may be employed, so that the same current detection circuit can be used to detect two different types of ac load currents. Specifically, the alternating current load connected to the first socket CN1 can be turned on to work, the pin RLY1 of the main control module outputs a high level to drive the first triode Q1 to be turned on, at this time, the first relay RY1 is pulled in, the pin RLY2 of the main control module outputs a low level, the second triode Q2 and the second relay RY2 are turned off, and the alternating current load connected to the second socket CN2 does not work. The current flowing through the input end of the current transformer L1 is the working current of the ac load connected to the first socket CN1, and the output current of the current transformer L1 is converted into an ac voltage by the third resistor R3 and output to the rear-end rectifying and filtering module.

Specifically, the relay power supply terminal + VCC may be dc 5V, dc 12V or dc 24V, and the first socket CN1 and the second socket CN2 are respectively connected to an ac load on the first socket CN1 and an ac load on the second socket CN 2. The first diode D1 and the second diode D2 can be selected from models of 1N4148 and the like, the first triode Q1 and the second triode Q2 can be selected from NPN triodes of 9014, S8050 and the like, the first resistor R1 and the second resistor R2 are selected from 2.2K-4.7K, the first relay RY1 and the second relay RY2 can be selected from a normally open relay with direct current 5V, direct current 12V or direct current 24V and rated voltage of over 250V, the direct current voltage of the first relay or the second relay is selected according to a selected power supply scheme, the rated current value of the first relay or the second relay is over 1.5 times of the actual load working current so as to prevent the temperature rise of internal contacts of the relay, and the first socket CN1 and the second socket CN2 are selected from sockets with wider pin pitch and current resistance models of VH-2A or VH-2 AW.

Example 3: referring to fig. 2, a schematic circuit diagram of an embodiment of the current detection circuit for different ac loads is shown. On the basis of embodiment 1, the current detection module specifically includes a current transformer L1 and a third resistor R3, wherein a first end of the current transformer L1 is connected to a first end of the third resistor R3, a second end of the current transformer L1 is connected to a second end of the third resistor R3, a third end of the current transformer L1 is connected to the load driving module, and a fourth end of the current transformer L1 is connected to the live line terminal AC _ L.

Specifically, the current transformer L1 plays a role in isolating the ac high voltage power from the dc low voltage power, when an ac current flows through the input terminal of the current transformer L1, an ac induced current is generated at the output terminal thereof, and the ac induced current flows through the third resistor R3 and is converted into a lower ac induced voltage.

The detection sensitivity of the alternating current load current is determined by the transformation ratio of the current transformer L1, a current transformer with the isolation withstand voltage of more than 3000V and the rated input current of more than 1.5 times larger than the actual alternating current load current is selected, and for the circuit with the total alternating current load current of not more than 3A, the current transformer can be selected from the model of the rated input current of 5A and the model of the ZHT107M with the transformation ratio of 1000: 1. The value of the third resistor R3 also directly affects the detection sensitivity of the alternating current load current, the larger the third resistor R3 is, the higher the output voltage sensed by the current detection circuit is, the value of the third resistor R3 should be adjusted according to the current size debugging of the maximum alternating current load and the minimum alternating current load which need to be detected, a 3K-10K resistor is generally selected, and the output voltage of the current transformer L1 meets the following two conditions:

condition 1: it is necessary to ensure that the amplitude of the ac voltage generated across the third resistor R3 by the current transformer L1 when the minimum ac load to be detected is turned on should be greater than the voltage drop of the third diode D3 to generate a rectified output voltage for the DECT pin of the main control module to perform AD detection.

Condition 2: it is required to ensure that the ac voltage amplitude generated by the current transformer L1 at the two ends of the third resistor R3 is rectified by the third diode D3, filtered by the first capacitor C1, and divided by the fourth resistor R4 and the fifth resistor R5 under the condition that the maximum ac load to be detected is turned on, and the voltage at the DECT pin of the main control module where the AD detection is performed should be less than 4/5 of the reference source voltage selected for AD sampling so as to avoid the occurrence of the overflow of the AD value and the false judgment of the load short circuit.

Example 4: referring to fig. 2, a schematic circuit diagram of an embodiment of the current detection circuit for different ac loads is shown. On the basis of embodiment 3, a specific rectifying and filtering module is further added, and the rectifying and filtering module includes a third diode D3 and a first capacitor C1, a first end of the third diode D3 is connected to a first end of the third resistor R3, a second end of the third diode D3 is connected to a first end of the first capacitor C1, and a second end of the first capacitor C1 is grounded.

Specifically, the ac induced voltage in the embodiment 3 is converted into a dc voltage after passing through the circuit in this embodiment.

Wherein D3 can be 1N4148 type, and C1 can be 47 uF-100 uF/25V electrolytic capacitor.

Example 5: referring to fig. 2, a schematic circuit diagram of an embodiment of the current detection circuit for different ac loads is shown. A specific voltage detection module is added on the basis of embodiment 4, and specifically, the voltage detection module includes a fourth resistor R4, a fifth resistor R5, and a second capacitor C2, wherein a first end of the fourth resistor R4 is connected to a second end of the third diode D3, a second end of the fourth resistor R4 is connected to a first end of the fifth resistor R5, a second end of the fifth resistor R5 is grounded, a first end of the fifth resistor R5 is further connected to a first end of the second capacitor C2, a first end of the second capacitor C2 is further connected to the main control module, and a second end of the second capacitor C2 is connected to a second end of the fifth resistor R5.

Specifically, this embodiment may be combined with embodiments 1 and 4, where the dc voltage signal output in embodiment 4 is divided by the fourth resistor R4 and the fifth resistor R5 and then transmitted to the DECT pin of the main control module for AD port detection, at this time, the dc voltage detected by the main control module corresponds to the working current of the ac load connected to the first socket CN1, and when the voltage value detected by the DECT pin of the main control module is smaller than the set voltage value, it is determined that the ac load connected to the first socket CN1 is open-circuited; when the DECT pin of the master control module performs AD detection, and the voltage value is greater than the set voltage value, it is regarded as a short circuit of the ac load current connected to the first socket CN 1. If the detected working current of the alternating current load connected to the first socket CN1 is not abnormal, the working mode is entered into a working mode of simultaneously turning on the alternating current load connected to the first socket CN1 and the alternating current load connected to the second socket CN2, at this time, the orifice of the RLY2 of the main control module outputs a high level to drive the second triode Q2 to be conducted, the second relay RY2 is pulled in, at this time, the alternating current load connected to the first socket CN1 and the alternating current load connected to the second socket CN2 simultaneously work, the current flowing through the input end of the current transformer L1 is the total working current of the alternating current load connected to the first socket CN1 and the alternating current load connected to the second socket CN2, the output current of the current transformer L1 is converted into an alternating current voltage through the third resistor R3, then rectified through the third diode D3, filtered by the first capacitor C1, the fourth resistor R4 and the fifth resistor R5, and then transmitted to the DECT pin of the main control module for, the dc voltage detected by the main control module corresponds to the total operating current of the ac load connected to the first socket CN1 and the ac load connected to the second socket CN 2. The main control module subtracts the working current value of the ac load connected to the first socket CN1 from the total working current value of the ac load connected to the first socket CN1 and the ac load connected to the second socket CN2, so as to obtain the working current of the ac load connected to the second socket CN 2. If the voltage detected by the pin DECT of the main control module by AD is larger than the set maximum voltage value, the AC load current on the second socket CN2 is considered to be out of standard, and the AC load on the second socket CN2 is judged to be short-circuited; if the voltage detected by the pin DECT of the main control module AD is less than the set minimum voltage value, the ac load current at the second socket CN2 is considered to be an open circuit. It can be understood that if the working current abnormality is detected when the ac load on the first socket CN1 is first turned on, where the abnormality includes an open circuit or a short circuit fault, the RY1 pin of the main control module immediately outputs a low level to turn off the above load with abnormal working, and simultaneously the RY2 pin of the main control module outputs a high level to separately turn on the ac load on the second socket CN2 for detection, and if the voltage detected by the DECT pin of the main control module in AD is greater than a set maximum voltage value, it is determined that the ac load on the second socket CN2 exceeds the standard, and it is determined that the ac load on the second socket CN2 is short-circuited; if the voltage value detected by the DECT pin of the master control module in AD is smaller than the set minimum voltage value, it is determined that the ac load on the second socket CN2 is open, and at this time, the RY2 pin of the master control module immediately outputs a low level, and the ac load on the second socket CN2 which is abnormally operated is turned off. After detecting the AC load fault, the main control module closes all loads to return to the standby mode and sends a fault prompt signal to remind a user.

Specifically, the dc voltage output in the embodiment 4 is divided by the circuit of this embodiment, i.e., the fourth resistor R4 and the fifth resistor R5, and then transmitted to the DECT pin of the main control module for AD detection, so as to prevent the rectified dc voltage from being higher than 4/5 of the reference source voltage selected by the AD sampling of the main control module, which causes the overflow of the AD value and misjudges the overflow as a load short circuit. The second capacitor C2 is used to prevent high frequency interference from affecting the accuracy of the DECT pin measurement of the main control module. When the alternating current load on the first socket CN1 or the alternating current load on the second socket CN2 works in an alternative mode, the DECT pin of the main control module performs AD to detect that the voltage value is greater than the set maximum voltage value, that is, the alternating current load current exceeds the standard, and the corresponding load is judged to be short-circuited; when the voltage value of the voltage value is detected to be smaller than the set minimum voltage value by AD of the DECT pin of the main control module, the corresponding AC load current is judged to be open-circuit.

The fourth resistor R4 and the fifth resistor R5 can select resistors of 4.7K-47K, wherein the proportional relation between the fourth resistor R4 and the fifth resistor R5 depends on the practical application scene, but the highest voltage detected by AD input to a DECT pin of the main control module for AD sampling is lower than 4/5 of the voltage of the selected reference voltage source, and C2 selects a capacitor of 100 nF/50V.

The main control module mentioned in the above embodiments selects a single chip with an a/D port, the type and number of I/O are determined according to specific loads, and the main control module can select suitable single chips such as HT66F004, HT66F0185 and the like.

The combination of the above embodiments can utilize one set of current transformer and its detection circuit to realize the detection of open circuit, short circuit and other fault types of two different types of ac loads. For better understanding of the content of the present invention, the following explains the content of the present invention by way of example, for an electric heater product, for example, an ac blowing fan can be started first, after the fan load current has stabilized after starting for 2 seconds, the load current detection is performed, and then the heating device is turned on to perform the load current detection; for example, for an air sterilizer and an air purifier product which adopt an alternating-current ultraviolet disinfection lamp, because the alternating-current ultraviolet disinfection lamp assembly can reach a stable load current value instantly, the alternating-current ultraviolet disinfection lamp can be turned on firstly for load current detection, and another air purifier product which is started slowly is turned on after 0.3 second for load current detection, so that a user generally does not feel the delay of load starting because the time interval of turning on the two loads is short. The method for detecting the current by time-sharing opening comprises the steps of firstly opening one alternating current load to detect the total current of a load loop, opening the other alternating current load to detect the total current of the load loop again, judging whether the load is in open circuit or short circuit fault or not by detecting the current increment of the total current of the front alternating current load loop and the rear alternating current load loop, and if a certain alternating current load is opened, judging that the alternating current load is in open circuit if no load current increment exists; if the load current increment exceeds the normal maximum starting current value when a certain load is opened, the alternating current load is regarded as a short circuit, and the main control module sends out a fault prompt signal, closes the alternating current load with the fault and returns to the standby state.

The selection of each part or device in the above embodiments may be performed according to actual situations, and is not limited to the selection of the above embodiments.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.

Claims

1. A circuit for detecting a common current for different ac loads, comprising:

the main control module is sequentially connected with the load driving module, the current detection module, the rectification filtering module and the voltage detection module, and the voltage detection module is connected with the main control module.

2. The circuit of claim 1, wherein the load driving module comprises a first relay, a second relay, a first diode, a second diode, a first triode, a second triode, a first resistor, a second resistor, a first socket, and a second socket, a first terminal of the first relay is connected to a first terminal of the first diode, a second terminal of the first relay is connected to a second terminal of the first diode, a second terminal of the first relay is further connected to a power supply, a collector of the first triode is connected to a first terminal of the first relay, an emitter of the first triode is grounded, a base of the first triode is connected to a first terminal of the first resistor, a second terminal of the first resistor is connected to the main control module, and a first terminal of the first socket is connected to a third terminal of an output of the first relay, the fourth end of first relay output connects current detection module, the zero line is connected to first socket second end, the first end of second relay is connected the first end of second diode, the second end of second relay is connected the second end of second diode, the second end of second relay still connects the power, the collecting electrode of second triode is connected the first end of second relay, the projecting pole ground connection of second triode, the base of second triode is connected the first end of second resistance, the second end of second resistance is connected main control module, the first end of second socket is connected the third end of second relay output, the fourth end of second relay output connects current detection module, the second socket second end is connected the zero line.

3. The current detection circuit shared by different alternating current loads according to claim 1, wherein the current detection module comprises a current transformer and a third resistor, the first end of the current transformer is connected with the first end of the third resistor, the second end of the current transformer is connected with the second end of the third resistor, the third end of the current transformer is connected with the load driving module, and the fourth end of the current transformer is connected with the live wire.

4. The circuit of claim 3, wherein the rectifying and filtering module comprises a third diode and a first capacitor, a first end of the third diode is connected to a first end of the third resistor, a second end of the third diode is connected to a first end of the first capacitor, and a second end of the first capacitor is grounded.

5. The circuit according to claim 4, wherein the voltage detection module comprises a fourth resistor, a fifth resistor, and a second capacitor, a first end of the fourth resistor is connected to the second end of the third diode, a second end of the fourth resistor is connected to the first end of the fifth resistor, a second end of the fifth resistor is grounded, the first end of the fifth resistor is further connected to the first end of the second capacitor, the first end of the second capacitor is further connected to the main control module, and the second end of the second capacitor is connected to the second end of the fifth resistor.