Load working state detection circuit

Abstract

The utility model discloses a load working state detection circuit, which is connected to a detection point between a load and a load driving circuit, and comprises a triode N25, a diode D26, a plurality of resistors and capacitors: a resistor R120, a resistor R121 and a resistor R122 are connected in series between the detection point and a ground wire; the base electrode of the triode N25 is connected to the connection point of the resistor R121 and the resistor R122, and the emitter electrode of the triode N25 is grounded; the load working state detection circuit comprises a triode N25, a collector electrode of the triode N25 is connected with a resistor R123, the resistor R123 is connected to a power supply, the collector electrode is grounded through a resistor R124 and a capacitor C63, a connection point of the resistor R124 and the capacitor C63 is set as a detection signal end DTFJ, and the signal end DTFJ is used for outputting a detection signal of the load working state detection circuit. According to the utility model, different faults are distinguished through different signal forms, so that the limitation of a traditional detection mode is avoided; the circuit can send out an alarm signal in time under the condition of open circuit or short circuit of the load, thereby ensuring the safety of the system.

Description

Technical Field

[0001] This utility model belongs to the field of circuit detection technology, and in particular relates to a load operating status detection circuit. Background Technology

[0002] Load status detection circuits are primarily used to improve the safety and reliability of equipment. They detect the operating status of the load to determine if any abnormalities have occurred, such as short circuits or open circuits. The background and significance of load status detection circuits are particularly important in the application scenarios of drying fans. Drying fans are commonly used in industrial production, such as in the drying processes of food, chemical, and textile industries. The stable operation of the fan directly affects the efficiency and quality of the drying process. Drying fans typically operate continuously for extended periods and are prone to failure due to unstable loads, overheating, and mechanical wear. These failures include short circuits or open circuits in the fan motor or jamming of the fan blades. Failure to detect these abnormalities in a timely manner can lead to equipment damage, energy waste, and even safety hazards. Therefore, load status detection circuits help monitor the operating status of the fan, ensuring it operates within its normal operating range.

[0003] The main types of existing load operating status detection circuits are as follows:

[0004] (1) Traditional current detection circuit: This type of circuit determines the load status by detecting the current change when the load is working. The disadvantage is that it is not sensitive enough for small current loads and is prone to false alarms when the current fluctuates greatly.

[0005] (2) Voltage detection circuit: The operating status is determined by monitoring the voltage change at the load end. This type of circuit is sensitive to voltage fluctuations, but it cannot effectively deal with short circuits or open circuits, especially when the load voltage is normal but an internal fault occurs, it cannot detect the problem in time.

[0006] (3) Temperature monitoring circuit: This circuit determines whether the load is working properly by monitoring the temperature of the load. Although this method is suitable for certain specific loads (such as motors), the response time is slow and it cannot immediately detect abnormal conditions such as load short circuits or open circuits.

[0007] The main drawback of these existing detection circuits is that they can mostly only detect a single type of fault and are susceptible to interference from environmental noise or other factors, leading to false alarms or missed alarms. Utility Model Content

[0008] To solve the above-mentioned technical problems, this utility model provides a load operating status detection circuit.

[0009] The technical solution provided by this utility model is as follows:

[0010] A load operating state detection circuit is provided, wherein the detection circuit is connected at a detection point between the load and the load driving circuit, and includes a transistor N25, a diode D26, and several resistors and capacitors: resistors R120, R121, and R122 are connected in series between the detection point and ground, and diode D26 and capacitor C62 are connected in parallel with resistor R122; the base of transistor N25 is connected to the connection point of resistors R121 and R122, and the emitter of transistor N25 is grounded; the collector of transistor N25 is connected to resistor R123, which is connected to a power supply, and the collector is also grounded through resistor R124 and capacitor C63; the connection point of resistor R124 and capacitor C63 is set as the detection signal terminal DT_FJ, and the signal terminal DT_FJ is used to output the detection signal of the load operating state detection circuit.

[0011] Furthermore, the load drive circuit includes a transistor N3 and a controllable switching element TR1; the collector of the transistor N3 is connected to the power supply through a resistor R19, the emitter of the transistor N3 is connected to the load through the controllable switching element TR1, and the base of the transistor N3 is provided with a control signal terminal AirDry_Fan, which is used to receive control signals.

[0012] Furthermore, a current-limiting filter circuit consisting of resistor R20 and capacitor C9 connected in parallel is provided between the connection point of the emitter of transistor N3 and TR1 and the ground line.

[0013] Furthermore, the controllable switching element TR1 is a bidirectional thyristor, a transistor, or a relay.

[0014] Preferably, a self-resetting overcurrent protector PPCT1 is connected in series between the load and the controllable switching element TR1.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects:

[0016] This invention can effectively detect different states of the fan load, such as normal operation, short circuit, and open circuit, and distinguish these states through different signal feedbacks (such as a 50Hz square wave and a constant high level). The main advantages of this circuit include: distinguishing different faults through different signal forms, avoiding the limitations of traditional detection methods; and the circuit can promptly issue alarm signals in the event of a load open circuit or short circuit, ensuring system safety. In summary, this invention has significant advantages in detection accuracy, fault differentiation, and anti-interference capabilities, effectively overcoming the shortcomings of traditional circuits. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0018] Figure 1 This is a schematic diagram of a load operating status detection circuit provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of a fan drive circuit provided in one embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] This embodiment provides a load operating status detection circuit, such as Figure 1 As shown, the detection circuit is connected between the fan load and the fan drive circuit. It determines whether the fan is working properly by detecting the feedback signal of the fan load under different states. Figure 1 In this code, "Fan" represents the fan load, which is the external fan. As a load, its switching is controlled by the fan drive circuit, and it operates under a 50Hz power signal during normal operation. "DT_Fan" represents the fan load detection signal point, which is used to connect to the load operating status detection circuit. Depending on the load's operating status, it outputs different signals (a 50Hz square wave or a constant high level), which are then transmitted to the back-end microcontroller for analysis.

[0022] The load operating status detection circuit uses an NPN transistor N25 as the main switching element and includes multiple resistors, capacitors, diodes, and other components. Specifically, resistors R120, R121, and R122 are connected in series between the input point of the detection circuit and ground. Resistor R122 is connected in parallel with diode D26 and capacitor C62. Diode D26 is used to limit the voltage in the circuit and protect subsequent components, while C62 acts as a filter to ensure signal stability. The base of transistor N25 is connected to the junction of resistors R121 and R122. Thus, the base voltage is controlled by the voltage divider effect of resistors R120, R121, and R122, while diode D26 provides protection. The emitter of transistor N25 is directly grounded, and the collector is connected to resistor R123, which is connected to a +5V power supply. The collector is also grounded through resistor R124 and capacitor C63 (C63 acts as a bypass to reduce high-frequency interference; R124 acts as a current-limiting resistor to prevent excessive output current). The junction of resistor R124 and capacitor C63 is set as the detection signal terminal DT_FJ, used to output the detection signal of the load operating status detection circuit to the back-end microcontroller. By reading the level signal at this port, the microcontroller can determine whether the fan is working normally.

[0023] like Figure 2As shown, this embodiment uses a fan drive circuit, which mainly consists of a power supply connected to the fan, a controllable switch element TR1, and an NPN transistor N3. The controllable switch element TR1, as the switching element in the circuit, controls the on / off state of the fan circuit. It is controlled by a microcontroller through control signals, thus turning the fan power supply on or off. Specifically, the collector of transistor N3 is connected to a +12V power supply through resistor R19 to provide bias voltage for subsequent circuits; the emitter of transistor N3 is connected to the fan load through a controllable switch element TR1, and a current-limiting filter circuit consisting of resistor R20 and capacitor C9 connected in parallel is set between the connection point of the emitter and TR1 and the ground wire; the base of transistor N3 has a control signal terminal AirDry_Fan, which is used to connect to a microcontroller. The control signal from the microcontroller controls the controllable switch element TR1. When the microcontroller sends an on signal, TR1 conducts, and the fan is powered on and starts working; when it sends an off signal, TR1 deactivates, and the fan stops working. In this embodiment, the controllable switch element TR1 is a JST131 bidirectional thyristor. When the control signal reaches the control terminal of the thyristor, the thyristor conducts, allowing current to flow through the fan, thereby driving the fan to work. Of course, the controllable switch element TR1 can also be a transistor or a relay. In this embodiment, a self-resetting overcurrent protector PPCT1 is also provided, which is connected in series between the fan and the bidirectional thyristor (TR1) to ensure that the current is cut off when the circuit is overcurrent, thus protecting the fan and other circuit components.

[0024] Table 1 Detection Status Table

[0025]

[0026] The core of the load operating status detection circuit provided in this embodiment lies in determining whether the fan load (Fan) is operating normally by detecting the feedback signal of the fan load under different states. As shown in Table 1, when TR1 is off, if the fan circuit is open-circuited, the DT_FJ port will feed back a constant high-level signal (instead of a 50Hz square wave). In this case, the microcontroller reads the constant high level and determines that the fan load has been disconnected (cannot be powered), thereby issuing a corresponding fault alarm or taking protective measures. When TR1 is on, if the fan circuit is short-circuited, the DT_FJ port will feed back a 50Hz square wave (instead of a constant high-level signal). In this case, the microcontroller reads the square wave signal and determines that the fan load has been short-circuited, thereby issuing a corresponding fault alarm or taking protective measures.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of different aspects of this utility model as described above. For the sake of brevity, they are not provided in detail; although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A load operating state detection circuit, characterized in that, The detection circuit is connected at the detection point between the load and the load drive circuit, and includes a transistor N25, a diode D26, and several resistors and capacitors: resistors R120, R121, and R122 are connected in series between the detection point and the ground line, and diode D26 and capacitor C62 are connected in parallel with resistor R122; the base of transistor N25 is connected to the connection point of resistors R121 and R122, and the emitter of transistor N25 is grounded; the collector of transistor N25 is connected to resistor R123, which is connected to the power supply, and the collector is also grounded through resistor R124 and capacitor C63. The connection point of resistor R124 and capacitor C63 is set as the detection signal terminal DT_FJ, which is used to output the detection signal of the load operating status detection circuit.

2. The load operating state detection circuit as described in claim 1, characterized in that, The load drive circuit includes a transistor N3 and a controllable switching element TR1; the collector of the transistor N3 is connected to the power supply through a resistor R19, the emitter of the transistor N3 is connected to the load through the controllable switching element TR1, and the base of the transistor N3 is provided with a control signal terminal AirDry_Fan, which is used to receive control signals.

3. The load operating state detection circuit as described in claim 2, characterized in that, A current-limiting filter circuit consisting of resistor R20 and capacitor C9 connected in parallel is provided between the emitter of transistor N3 and the connection point of TR1 and the ground line.

4. The load operating state detection circuit as described in claim 2, characterized in that, The controllable switching element TR1 is a bidirectional thyristor, transistor, or relay.

5. The load operating state detection circuit as described in claim 2, characterized in that, A self-resetting overcurrent protector PPCT1 is connected in series between the load and the controllable switching element TR1.

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