CN201233424Y - Dc fan failure testing apparatus - Google Patents

Abstract

The utility model discloses a direct-current fan malfunction detection device, which comprises a signal detection unit and a signal processing unit, wherein, the signal detection unit is arranged on a direct-current fan power supply circuit, and the signal detection unit is serially connected with a direct-current fan; the signal detection unit comprises a diode unit and a resistor unit tat is connected with the diode unit in parallel; the signal processing unit is used for comparing the voltage detection signal that is outputted by the signal detection unit with a threshold value voltage and for outputting the high-low electric level signal according to the comparison result. With the above technical proposal, the detection device realizes the detection of the direct-current fan current; compared with the prior art, the detection device has high reliability and low cost; moreover, the detection device can adopt the signal that is outputted when the fan is blocked or normally operated to be distinguished, and has large detection power and can detect various malfunctions.

Description

A DC fan fault detection device

technical field

The utility model relates to a DC fan fault detection device, in particular to a DC fan fault detection device for detecting whether the DC fan is in place, has an open circuit fault or is blocked.

Background technique

Existing power electronic equipment often needs to use a fan to cool the equipment due to its high loss. Because DC fans are easy to adjust their speed, DC fans are often used for equipment cooling. However, if the fan fails, such as when it is not present, breaks out, or is locked, the device is likely to overheat and be damaged. Therefore, fan fault detection needs to be used to determine the status of the fan.

At present, DC fans are divided into two types with detection signals and without detection signals. For DC fans with detection signals, in order to detect the status of the fans, related chips and circuits must be added, which increases the cost. Therefore, in many cases, a DC fan with no detection signal is used. Fans without detection signals generally only provide power and ground leads. At this time, if the status of the fan needs to be detected, an external circuit is required. Most of the existing circuits of this type are detected by detecting the fan current.

The commonly used fan detection methods are as follows:

1. The detection method of sampling the fan current by using the current sensor

The current sensor can also be used to detect the fan current, so as to judge the working status of the fan according to the fan current. The principle is shown in Figure 1. The current sensor is generally a Hall current sensor or a current transformer. This method does not have the problem of resistance heating, but there will still be a situation where the output signal changes greatly when the fan speed is adjusted. Moreover, the price of the sensor is relatively high, which increases the cost of the equipment. Using a current sensor to detect fan failure, considering its increased cost, it is cheaper to choose a fan with a detection signal. Therefore, choosing a current sensor to sample the fan current seems overkill.

2. The fan detection method whose patent publication number is CN101113992.

In the patent publication number CN101113992, a diode is connected in series in the fan power supply circuit, and the fan state is judged by the voltage drop on the diode, as shown in FIG. 2 . However, this method cannot detect the state of the fan stalling. For a DC fan with stall protection, when the fan is blocked, the fan is in a high-impedance state, and a small current flows through it. Therefore, the diode is at a high level, and the fan is still detected to be in position normally, so it cannot be judged that the fan is blocked. And for the detection of multiple fans, the circuit must output multiple signals correspondingly, and the "AND" and "OR" relationship processing of multiple signals must be connected with other signal processing circuits, thereby increasing the cost.

It can be seen that certain problems still exist in the prior art, and further improvements are needed.

Utility model content

The purpose of the utility model is to provide a DC fan fault detection device, which overcomes the problem of incomplete function or high cost of DC fan fault detection in the prior art.

In order to achieve the above object, the utility model adopts the following technical solutions:

The utility model provides a DC fan fault detection device, the detection device includes: a signal detection unit for converting the current signal on the DC fan power supply circuit into a voltage signal output, and a signal detection unit for receiving the output of the signal detection unit The signal processing unit of the voltage detection signal; the signal detection unit is arranged on the DC fan power supply circuit, and the signal detection unit is connected in series with the DC fan; the signal detection unit includes: a diode unit, and the diode unit A resistor unit connected in parallel, the signal processing unit is used to compare the voltage detection signal output by the signal detection unit with a threshold voltage, and output high and low level signals according to the comparison result.

The device described above, wherein the diode unit includes a diode or a circuit composed of at least two diodes connected in series; a node connected in parallel between the diode unit and the resistance unit is connected to the ground terminal of the DC fan power supply circuit or the The positive voltage input terminal of the DC fan, the two ends of the resistance unit or the diode unit serve as the voltage detection signal output terminal of the signal detection unit.

Said device, wherein said resistance unit comprises one resistance or a circuit composed of at least two resistances connected in series.

The device, wherein the signal processing unit includes: an optocoupler circuit, the optocoupler circuit includes a first pull-up resistor and an optocoupler, and the anode of the primary side diode of the optocoupler is connected to a voltage of the signal detection unit The detection signal output terminal, the primary diode cathode of the optical coupler is connected to another voltage detection signal output terminal of the signal detection unit, and the secondary triode collector of the optical coupler is connected to a DC through the first pull-up resistor. The output end of the power supply, the emitter of the triode on the secondary side of the optical coupler is connected to the signal ground end.

The device, wherein the signal processing unit includes: a comparison circuit, the comparison circuit includes: an operational amplifier and a second pull-up resistor, and the voltage detection signal output terminal of the signal detection unit is connected to one of the operational amplifiers The other input end of the operational amplifier is connected to a reference voltage output end, and the output end of the operational amplifier is connected to an output end of a DC power supply through the second pull-up resistor.

The device, wherein the signal processing unit further includes: a filter circuit, which is connected in series between the voltage detection signal output terminal of the signal detection unit and the input terminal of the optocoupler circuit or the comparison circuit The interval is used to filter out the voltage noise of the output signal of the signal detection unit.

In the device described above, when multiple DC fans are detected, each DC fan corresponds to a signal detection unit and a signal processing unit, and the output of each signal processing unit is connected in series or in parallel to realize the detection of multiple DC fans. detection.

The device described above, wherein the filter circuit is an RC filter circuit.

The device, wherein the filter circuit includes a resistor and a capacitor, one end of the resistor is connected to the anode of the diode unit in the signal detection unit, and the other end of the resistor is connected to one end of the capacitor and the An optocoupler circuit or the input end of the comparison circuit; the other end of the capacitor is connected to the cathode of the diode unit in the signal detection unit.

By adopting the above technical scheme, the utility model realizes the detection of the DC fan current, and compared with the prior art, it has high reliability and low cost; and it can output unused signals for The difference is that the detection strength is greater and there are more types of detection faults.

Description of drawings

1 is a schematic diagram of a fan fault detection method using a current sensor to sample fan current in the prior art;

Fig. 2 is a schematic diagram of a fan detection method whose patent publication number is CN101113992;

Fig. 3 is the circuit schematic diagram of the utility model;

Fig. 4 is the circuit schematic diagram of embodiment 1 and embodiment 3;

Fig. 5 is the circuit schematic diagram of embodiment 2;

Fig. 6 is the circuit schematic diagram of embodiment 4 and embodiment 5;

Fig. 7 is the circuit schematic diagram of embodiment 6;

FIG. 8 is a schematic diagram of the circuit principle of Embodiment 7. FIG.

Detailed ways

As shown in Figure 3, the utility model proposes a high-reliability, low-cost DC fan fault detection device, which includes the detection device includes: used to convert the current signal on the DC fan power supply circuit into a voltage signal output A signal detection unit 210, and a signal processing unit 220 for receiving a voltage detection signal output by the signal detection unit; the signal detection unit 210 is arranged on the DC fan power supply circuit, and the signal detection unit 210 and the DC fan connected in series; the signal processing unit 220 is used to compare the voltage detection signal output by the signal detection unit 210 with a threshold voltage, and output a high or low level signal according to the comparison result, that is, output a DC fan fault detection signal. When the fan is not in place, has an open circuit fault or is blocked, the signal processing unit 220 can send out a signal that is different from that sent out when the fan is working normally.

Various preferred embodiments of the present utility model will be described in detail below in conjunction with the accompanying drawings.

Embodiment 1: As shown in FIG. 3 , the signal detection unit 210 in this embodiment includes: a diode unit 211, and a resistance unit 212 connected in parallel with the diode unit 211, and a node in which the diode unit 211 is connected in parallel with the resistance unit 212 is connected The ground terminal GND1 of the DC fan power supply circuit, and the other node connected in parallel with the diode unit 211 and the resistance unit 212 is connected to the negative voltage input terminal of the DC fan, and the two ends of the resistance unit 212 or the diode unit 211 are used as the signal detection unit 210 The output terminal of the voltage detection signal will be connected with the input terminal of the signal processing unit 220 . The diode unit 211 here may contain one diode, or a circuit composed of at least two diodes connected in series; the resistance unit 212 here contains one resistor, or a circuit composed of at least two resistors connected in series.

Embodiment 2: As shown in FIG. 5 , the difference between this embodiment and Embodiment 1 is that a node where the diode unit 211 and the resistance unit 212 are connected in parallel is connected to the output terminal of the power supply VCC1 of the DC fan power supply circuit, and the diode unit 211 and the resistance unit 212 are connected to each other. The other node of the resistor unit 212 connected in parallel is connected to the positive voltage input terminal of the DC fan. Other components and connections are the same as in Embodiment 1.

It can be seen from the above two embodiments that the signal detection unit 210 of the present invention can have two installation positions, for example, it can be set between the negative voltage input end of the DC fan and the ground end of the DC fan power supply circuit, or it can be set Between the power output terminal of the DC fan power supply circuit and the positive voltage input terminal of the DC fan. Both of these two ways can realize the function of the utility model to detect the failure of the DC fan.

Implementation 3: As shown in Figure 4, the difference between this embodiment and Implementation 1 is that the signal processing unit 220 includes: an optocoupler circuit 221, the optocoupler circuit 221 includes a first pull-up resistor R3 and an optocoupler D1, the optocoupler The primary side diode anode of D1 is connected to a voltage detection signal output terminal of the signal detection unit 210, that is, as shown in Figure 4, the output terminal can be the anode of the diode unit in the signal detection unit 210, and the primary side diode cathode of the optical coupler D1 is connected to Another voltage detection signal output terminal of the signal detection unit 210, as shown in FIG. R3 is connected to the output terminal of a DC power supply VCC2, and the emitter of the secondary transistor of the optocoupler D1 is connected to the signal ground terminal GND2. In this embodiment, the turn-on voltage of the primary side diode of the optical coupler D1 is the threshold voltage indicated above. Other components and connections are the same as in Embodiment 1. In this embodiment, since the optocoupler has the function of isolating signals, the position of the signal detection unit and the DC fan can be changed as shown in Figure 5, so as long as the voltage applied to the primary side diode of the optocoupler remains unchanged, the detection circuit can still work normally .

Embodiment 4: As shown in FIG. 6, the difference between this embodiment and Embodiment 1 is that the signal processing unit 220 may include: a comparison circuit 223, and the comparison circuit 223 includes: an operational amplifier A1 and a second pull-up resistor R4, The voltage detection signal output terminal of the signal detection unit 220 is connected to one input terminal of the operational amplifier A1, the other input terminal of the operational amplifier A1 is connected to a reference voltage VREF output terminal, and the output terminal of the operational amplifier A1 is connected through the second pull-up resistor R4. The output terminal of the current power supply VCC2. Other components and connections are the same as in Embodiment 1. In this embodiment, the comparator is used instead of the optocoupler to process the signal, and the reference voltage VREF of the comparison signal, that is, the above-mentioned threshold voltage, can be selected to make the circuit more flexible. When the voltage on the diode in the signal detection unit is higher than the reference voltage VREF, the DC fan signal is low, indicating that the fan is normal; when the voltage on the diode in the signal detection unit is lower than the reference voltage VREF, the fan signal is high, indicating that the fan is faulty . In an application, the reference voltage VREF may be 0.7V.

In this embodiment, one input terminal of the operational amplifier A1 is connected to the anode of the diode unit in the signal detection unit 210 shown in FIG. 6 , and the cathode of the diode unit in the signal detection unit 210 is connected to the ground terminal GND1 of the DC fan power supply circuit. As shown in Figure 6, in this embodiment, the inverting input terminal of the operational amplifier A1 is used as the input terminal of the voltage detection signal, and the non-inverting input terminal of the operational amplifier A1 is used as the input terminal of the reference voltage VREF; on the contrary, if the non-inverting input terminal of the operational amplifier A1 The input terminal is used as the input terminal of the voltage detection signal, and the output signal of the operational amplifier A1 is just opposite to that shown in FIG. 6 .

Embodiment 5: As shown in Figures 4, 6 and 7, the difference between this embodiment and Embodiment 3 or 4 is that the signal processing unit 220 may also include: a filter circuit 222, which is connected in series to the signal detection Between the output terminal of the voltage detection signal of the unit 210 and the input terminal of the optocoupler circuit 221 or the comparison circuit 223 is used to filter out the voltage noise of the output signal of the signal detection unit. Other components and connections are the same as those in implementation 3 or 4. The filter circuit here can be an RC filter circuit, which includes a resistor R2 and a capacitor C1, as shown in Figures 4 to 6, one end of the resistor R2 is connected to the anode of the diode unit in the signal detection unit 210, and the other end of the resistor R2 is connected One end of the capacitor C1 is connected to the anode of the primary diode of the optocoupler D1 in the optocoupler circuit 221 , or the inverting input end of the operational amplifier A1 in the comparison circuit 223 ; the other end of the capacitor C1 is connected to the cathode of the diode unit in the signal detection unit 210 .

It can be seen from the above-mentioned embodiment 3 and embodiment 4 that they provide two relatively simple and low-cost implementation modes for realizing the comparison function of the signal processing unit. Of course, the utility model is not limited to these two modes. The signal processing unit Other methods or modified forms of the above two methods may also be used. In addition, it can be seen from Embodiment 5 that in order to save costs, the utility model adopts an RC filter circuit with a lower cost. Of course, the utility model is not limited thereto, and any filter circuit well known to those skilled in the art can also be used in here.

Embodiment 6: When two or more DC fans need to be detected at the same time, each DC fan can be made to correspond to a signal detection unit shown in Figure 3 and a signal processing unit shown in Figure 3, and then each The output of the signal processing unit is connected in series to realize the detection of multiple DC fans. After the series connection, the output signals of each signal processing unit form the logic of "OR".

As shown in Figure 7, when the circuit shown in Figure 4 is used to detect two DC fans, the schematic diagram of the circuit principle of "OR" logic is formed by connecting the DC fan fault detection signals of the two DC fans in series, in which the diode VD1 , VD2 and resistor R1 form the signal detection circuit of DC fan 1, resistor R2 and capacitor C1 form the RC filter circuit of DC fan 1, optical coupling D1 and resistor R3 form the signal processing unit of the DC fan 1; diodes VD3, VD4, Resistor R5 constitutes the signal detection circuit of the DC fan 2, resistor R6 and capacitor C2 constitute the RC filter circuit of the DC fan 2, optical coupling D2 and resistor R3 constitute the signal processing unit of the DC fan 2. When there are two fans, the pull-up resistor R4 in one of the signal processing units can be reserved, and the collector of the optocoupler secondary transistor of one signal processing unit is connected to the emitter of the optocoupler secondary side of the other signal processing unit. That is, let the triodes on the secondary side of the optocoupler in all signal processing units be connected in series to form a total DC fan fault detection signal. When any fan fails, the corresponding optocoupler secondary triode will not conduct, and the DC fan fault detection signal is A high level indicates a fan failure, and the DC fan failure detection signal is formed into an "OR" logic. By analogy, when there are three or more fans, the "or" logic can be formed by connecting the corresponding DC fan fault detection signals in series.

Embodiment 7: When two or more DC fans need to be detected at the same time, each DC fan can also be made to correspond to a signal detection unit shown in Figure 3 and a signal processing unit shown in Figure 3, and then by The output of each signal processing unit is connected in parallel to realize the detection of multiple DC fans. After parallel connection, the output signals of each signal processing unit constitute the logic of "AND". The difference between this embodiment and Embodiment 5 is that this embodiment adopts a parallel connection mode.

As shown in Figure 8, when the circuit shown in Figure 4 is used to detect two DC fans, the schematic diagram of the circuit principle of "AND" logic is formed by connecting the DC fan fault detection signals of the two DC fans in parallel, in which the diode VD1, VD2 and resistor R1 form the signal detection circuit of DC fan 1, resistor R2 and capacitor C1 form the RC filter circuit of DC fan 1, optical coupler D1 and resistor R3 form the signal processing unit of the DC fan 1; diodes VD3 and VD4 , Resistor R5 forms the signal detection circuit of DC fan 2, resistor R6 and capacitor C2 form the RC filter circuit of DC fan 2, optical coupler D2 and resistor R3 form the signal processing unit of this DC fan 2, the composition and diagram in Figure 8 7, except that in the output part of the optocoupler circuit, Figure 8 adopts a parallel mode, and Figure 7 adopts a series mode. When there are two fans, the pull-up resistor R4 in one of the signal processing units can be reserved, and the collector of the optocoupler secondary transistor of one of the signal processing units is connected to the collector of the optocoupler secondary side of the other signal processing unit. The pole is connected to the emitter, that is, the transistors on the secondary side of the optocoupler in all detection circuits are connected in parallel to form a total DC fan fault detection signal. When all the fans fail, the corresponding optocoupler secondary triodes are all non-conductive, and the DC fan failure detection signal is at a high level, indicating a fan failure, achieving the "AND" logic of the DC fan failure detection signal. By analogy, when there are three or more fans, the corresponding DC fan fault detection signals are connected in parallel to form an "AND" logic.

When the utility model realizes DC fan fault detection, first, through a signal detection unit connected in series on the DC fan power supply circuit, the current signal on the DC fan power supply circuit is converted into a voltage signal output; The signal processing unit of the voltage detection signal output by the unit compares the voltage detection signal output by the signal detection unit with a threshold voltage, and outputs high and low level signals according to the comparison result. The following uses the embodiments shown in Figures 4 and 5 to describe its working principle in detail. In the application, the fan power supply VCC1 is 24V, the fan signal power supply VCC2 is 9V, and the pull-up circuit R4 or R3 is 5KΩ; RC is composed of R2 and C1 The filter circuit filters the voltage noise in the detection signal, R2 can be 50Ω, and C1 can be 10uF.

As shown in Figures 4 and 5, the signal processing circuit 220 uses an optocoupler for signal comparison and outputs a DC fan fault detection signal. Since the signal detection unit needs to conduct the diode of the optocoupler in the subsequent signal processing unit, the signal detection unit outputs The voltage must be higher than the conduction voltage of the diode on the primary side of the optocoupler, so the signal detection unit adopts the form of connecting two diodes VD1 and VD2 in series, and then connecting them in parallel with the resistor R1.

When the fan is working normally, the signal detection unit 210 outputs a high voltage, and the voltage drop on the primary side diode of the optocoupler D1 in the signal processing unit 220 is about 1.4V, and the primary side diode of the optocoupler D1 is turned on, so that the secondary side of the optocoupler D1 On, the DC fan fault detection signal is at low level, indicating that the DC fan is not faulty. Due to the clamping effect of two diodes VD1 and VD2, the voltage on R1 is about 1.4V. R1 is 50Ω, and the power on R1 is about 1.4×1.4/50＝0.0392W. It is enough to use a general 1/4W or even 1/8W low-power resistor. When the fan is running at low speed, even if the current is reduced to half of normal, the voltage drop across the diode will not change much.

When the DC fan is disconnected or not connected, the voltage on the diode is zero, and the signal detection unit outputs a low voltage, then the voltage on the primary side diode of the optocoupler D1 in the signal processing unit 220 is very low, and the primary side diode of the optocoupler D1 is not conducting. Make the secondary side of the optocoupler non-conductive, and the DC fan fault detection signal is at high level, indicating that the fan is faulty. Moreover, when the DC fan is blocked, the fan is in a high-impedance state, and the fan flows a small current. At this time, due to the small resistor R1 connected in parallel, the diodes VD1 and VD2 are still at low levels, so the signal processing unit The output will also be high. Yes, if the technical solution provided by the utility model is adopted, it is possible to simultaneously detect the stalled rotation of the DC fan, the disconnection is not in place, or the normal operation.

In summary, by adopting the above technical solutions, the utility model realizes the detection of the current of the DC fan, and uses the tube voltage drop when the diode is turned on to judge the normal operation of the fan; when the fan is blocked, the fan is at high In the resistance state, there is a small current passing through, and the voltage on the diode is clamped by a small resistance, so as to judge that the fan is in a fault state; the signal is converted into a digital quantity by using an optocoupler, and provided to the monitoring system. When there are multiple fans, the fan fault signals can also be directly connected in series or in parallel to form the logic of "or" or "and", which can meet the requirement of reducing the number of subsequent monitoring system interfaces. Since the resistor R1 of the present invention does not need to flow through the fan current, it only needs to use a general low-power resistor; since the optocoupler of the present invention does not need to transmit high-speed signals, it does not need to use a high-cost high-speed optocoupler. It can be seen that the utility model overcomes the problems of incomplete function or high cost in the prior art, and proposes a high-reliability, low-cost DC fan fault detection method and device.

The illustrations of the above-mentioned specific steps are relatively specific, and cannot therefore be considered as limiting the scope of protection of the patent of the utility model, and the scope of protection of the patent of the utility model should be based on the appended claims.

Claims (9)

1, a kind of DC fan failure detector, described pick-up unit comprises: be used for the current signal on the DC fan feed circuit is converted into the detecting signal unit of voltage signal output, and be used to receive the signal processing unit of the voltage detection signal of described detecting signal unit output; Described detecting signal unit is arranged on the described DC fan feed circuit, and described detecting signal unit is connected with DC fan; It is characterized in that described detecting signal unit comprises: diode, and and described diode parallel resistor unit;

Described signal processing unit is used for the voltage detection signal of more described detecting signal unit output and the size of a threshold voltage, and according to comparative result output high-low level signal.

2, device according to claim 1 is characterized in that, described diode contains a diode or at least two circuit that the diode series connection constitutes; Described diode is connected the ground end of described DC fan feed circuit or the positive voltage input end of described DC fan with the node that resistance unit is in parallel, and the two ends of described resistance unit or described diode are as the voltage detection signal output terminal of described detecting signal unit.

3, device according to claim 1 and 2 is characterized in that, described resistance unit contains a resistance or at least two circuit that the resistance series connection constitutes.

4, device according to claim 1, it is characterized in that, described signal processing unit comprises: a smooth lotus root circuit, this light lotus root circuit comprises first pull-up resistor and light lotus root, the former limit diode anode of described smooth lotus root connects a voltage detection signal output terminal of described detecting signal unit, the former limit diode cathode of described smooth lotus root connects another voltage detection signal output terminal of described detecting signal unit, the secondary transistor collector of described smooth lotus root connects the output terminal of a direct current power supply by described first pull-up resistor, and the secondary transistor emitter of described smooth lotus root connects the signal ground end.

6, device according to claim 1, it is characterized in that, described signal processing unit comprises: a comparator circuit, this comparator circuit comprises: the operational amplifier and second pull-up resistor, the voltage detection signal output terminal of described detecting signal unit connects an input end of described operational amplifier, another input end of described operational amplifier connects a reference voltage output end, and the output terminal of described operational amplifier connects the output terminal of a direct current power supply by described second pull-up resistor.

7, according to claim 4 or 6 described devices, it is characterized in that, described signal processing unit also comprises: a filtering circuit, this filtering circuit is connected between the input end of the voltage detection signal output terminal of described detecting signal unit and described smooth lotus root circuit or described comparator circuit, in order to leach the voltage noise of described detecting signal unit output signal.

8, device according to claim 1, it is characterized in that, when detecting a plurality of DC fan, the corresponding detecting signal unit of each DC fan and a signal processing unit are realized detection to a plurality of DC fan by the mode of the output of each signal processing unit being carried out serial or parallel connection.

9, device according to claim 7 is characterized in that, described filtering circuit is the RC filtering circuit.

10, device according to claim 9, it is characterized in that, described filtering circuit comprises a resistance and an electric capacity, one end of described resistance connects the anode of diode in the described detecting signal unit, and the other end of described resistance connects an end of described electric capacity and the input end of described smooth lotus root circuit or described comparator circuit; The other end of described electric capacity connects the negative electrode of diode in the described detecting signal unit.

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