CN109630448B - Direct current fan fault detection circuit - Google Patents
Direct current fan fault detection circuit Download PDFInfo
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- CN109630448B CN109630448B CN201811327895.4A CN201811327895A CN109630448B CN 109630448 B CN109630448 B CN 109630448B CN 201811327895 A CN201811327895 A CN 201811327895A CN 109630448 B CN109630448 B CN 109630448B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
- F04D27/001—Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring
Abstract
The invention relates to a direct current fan fault detection circuit which comprises a differential current detection circuit, a filter circuit and a time delay protection circuit, wherein the working current of a direct current fan passes through the differential current detection circuit to obtain sampling voltage, the sampling voltage is output to the filter circuit for filtering to obtain a voltage signal proportional to the direct current fan current, the voltage signal is output to the time delay protection circuit to obtain a fault voltage signal of the direct current fan, and the fault voltage signal is output. The circuit of the invention can effectively detect and alarm two fault states of short circuit and locked rotor of the fan.
Description
Technical Field
The invention relates to a fault of an aviation electrical system, and belongs to the field of electrical safety. In particular to a current acquisition and fault detection circuit of an aviation power supply low-voltage direct-current cooling fan.
Background
The reliability of an aviation power supply as an important component of a multi-electric aircraft is directly related to the safety of the whole aircraft. The overheating of components is closely related to the reliability of power supply products, and the thermal design and overheating protection of the power supply products are more and more important. The derating design and the thermal design are matched to enable the components to work within a rated temperature range, but once the fan is damaged, the temperature of the product can rise sharply, and finally the product is damaged or the service life of the product is shortened. The fan fault detection function of the aviation power supply product is particularly important.
The failure mode of the low-voltage direct-current cooling fan is stalling, and can be caused by two factors, namely open circuit and locked rotor. The current of all fans is zero under the condition of open circuit, the current of the ordinary fan is about 3 times of the rated current when the ordinary fan is started and locked, and the intelligent fan adopts soft start and locked-rotor current limiting to ensure that the fault current of the intelligent fan is less than the rated current. Therefore, whether the air outlet fan has a fault state or not can be judged by sampling and conditioning the current of the fan.
Two popular current detection techniques are resistance sampling and hall sampling. The resistance sampling method has low cost and simple circuit, but the high-power resistance temperature drift is more obvious. The Hall sampling method has high cost and low power consumption, but has larger current measurement error in a small range, is easily influenced by an external magnetic field, and has larger volume.
Disclosure of Invention
The purpose of the invention is as follows:
the invention aims to provide a reliable current acquisition and fault detection circuit for an aviation power supply low-voltage direct-current cooling fan, so as to solve the problem of power supply overheating caused by fan faults due to lack of fault protection of the aviation power supply cooling fan.
The technical scheme adopted by the invention is as follows:
a direct current fan fault detection circuit is composed of a differential current detection circuit, a filter circuit and a time delay protection circuit; the working current of the direct current fan passes through the differential current detection circuit to obtain sampling voltage, the sampling voltage is output to the filter circuit for filtering, a voltage signal proportional to the direct current fan current is obtained and output to the time delay protection circuit, a fault voltage signal of the direct current fan is obtained, and fault output is carried out.
The differential current detection circuit is characterized by comprising an operational amplifier N1A, acquisition resistors R15-R24, rectifier diodes V5-V8, a bypass capacitor C5 and proportional control resistors R11, R14, R28 and R29;
collecting resistors R15-R24 are connected in parallel, collected current of the direct current fan is converted into voltage signals, rectifying diodes V5 and V6 are connected in parallel, V7 and V8 are connected in parallel and then connected in series between the collecting resistors and the ground, the reverse terminal voltage of the operational amplifier N1A is boosted, proportional adjusting resistors R14 and R11 are connected with a pin 3 at the same phase end of the operational amplifier N1A, the other end of R14 is connected with one parallel end of the collecting resistors, the other end of R11 is grounded, the proportional adjusting resistors R28 and R29 are connected with a pin 2 at the reverse end of the operational amplifier N1A, the other end of R28 is connected with the other parallel end of the collecting resistors, the other end of R29 is connected with an output pin 1 of the operational amplifier N1A, pin 8 is connected with 18V power supply, a pin 4 of the operational amplifier N1A is grounded, a pin 8 of the operational amplifier N1A and the ground are connected with a bypass capacitor C5.
The circuit is characterized in that the filter circuit comprises a resistor R25 and a capacitor C7, the output of the differential current detection circuit is connected with the reverse end of a comparator U1A with delay protection through a resistor R25, and the capacitor C7 is connected between the reverse end of the comparator U1A with delay protection and the ground.
The time-delay protection circuit is characterized by comprising a two-stage voltage comparator circuit, wherein a charging circuit consisting of a comparator U1A, a resistor R9 and a capacitor C6 jointly forms a first-stage voltage comparator circuit, a first-stage voltage reference signal VH is connected to the in-phase end of the comparator U1A, a pin 8 of the comparator U1A is connected with 18V for power supply, a pin 4 is grounded, a bypass capacitor C4 is connected between the pin 8 and the ground, one end of the capacitor C6 is connected with a pin 1 at the output end of the comparator U1A, and the other end of the capacitor C6 is grounded; one end of a resistor R9 of the delay protection circuit is connected with a pin 1 at the output end of a comparator U1A, the other end of the resistor R9 is connected with an 18V power supply, a voltage signal which is proportional to the direct current fan current is compared with a voltage reference signal VH by the comparator U1A, the input voltage of the second-stage voltage comparator circuit is obtained, and the capacitor C6 is charged and discharged;
a voltage reference circuit consisting of the comparator U1B, a resistor R10 and a voltage regulator tube V5 jointly forms a second-stage voltage comparator circuit, one end of the resistor R10 of the voltage reference circuit is connected with 18V, and the other end of the resistor R10 of the voltage reference circuit is connected with a reverse end pin 6 of the comparator U1B; the forward end of a voltage regulator tube V5 of the voltage reference circuit is grounded, the reverse end of the voltage regulator tube V5 is connected with the reverse end pin 6 of a comparator U1B, the output end pin 1 of the comparator U1A is connected to the in-phase end pin 5 of the comparator U1B, a pull-up resistor R12 is further connected between the output pin 7 of the comparator U1B and the 18V power supply, the output voltage of the comparator U1A and the regulated voltage of the voltage regulator tube V5 jointly determine the output level signal of the comparator U1B, and if the direct current fan fails, the output level signal of the comparator U1B is at a high level.
The direct current fan is a low-voltage direct current fan, the direct current fan has a blocking and rotating hiccup protection function, and the current flowing through the direct current fan does not exceed half of rated working current of the fan when a blocking and rotating fault occurs.
The proportional control resistor is characterized in that the proportional control resistor R14 is R28, and the proportional control resistor R11 is R29.
The operational amplifier N1A is an operational amplifier powered by a single power supply.
The direct current fan fault detection circuit is characterized in that the output of the direct current fan fault detection circuit is low level and indicates that the direct current fan works normally, and the output of the direct current fan fault detection circuit is high level and indicates that the direct current fan is in fault.
The invention has the beneficial effects that:
the current acquisition and fault detection circuit of the low-voltage direct current fan of the aviation power supply adopts the operational amplifier powered by the single power supply, saves the design of a positive and negative power supply circuit, and simplifies the complexity of circuit design. The differential sampling precision of the current signal can be effectively ensured by carrying out voltage lifting on the reverse end of the operational amplifier through the diode connected in series in the sampling circuit. The current of the fan in the starting process is smaller than the rated current, the false alarm fault in the starting process can be avoided through the delay circuit of the first-stage comparator, and the delay alarm protection is carried out on the working conditions that the current is smaller than the rated current, such as power failure, locked rotor and the like.
Drawings
FIG. 1 is a schematic block diagram of fan fault detection
FIG. 2 is a circuit diagram of differential current detection
FIG. 3 is a diagram of a filter circuit and a delay protection circuit
Detailed Description
The invention is described in further detail below with reference to the drawings.
FIG. 1 is a schematic diagram of the FAN failure detection, in which the system inputs are the system power supply terminals 28VDC and GND, and the system outputs are the failure alarm output terminals FAN _ ERR and GND. The fans are connected in series at the input end of the direct current fan fault detection circuit.
The fan fault detection board is mainly divided into 5 functional areas, namely a differential current detection circuit, a filter circuit, a delay protection circuit, a fault output circuit, a power supply and a reference circuit.
Fig. 2 shows a differential current detection circuit, in which a sampling resistor and a rectifying diode are connected in series to a fan power supply circuit. The sampling resistor adopts 10 resistors for shunt in parallel, converts a fan current signal into a voltage signal on the resistor, and when the sampling resistor value is R and the fan current is I0, the differential voltage value of the sampling resistor is VO. The diode adopts two series and two connection modes. The diodes are connected in parallel so that the two diodes share the fan current. The diode and the sampling resistor flow power current, and the power consumption of each component can be reduced by parallel connection, so that the temperature rise of each component is reduced. In order to improve the reliability of the system, the diode and the sampling resistor are both arranged on the front surface of the PCB and keep the air circulation.
In order to simplify the design of the power supply circuit, the differential sampling circuit adopts an operational amplifier powered by a single power supply. When the voltage of the input end of the operational amplifier is smaller than or close to 0V, the operational amplifier cannot work normally. Therefore, a direct current bias needs to be introduced to raise the level of the voltage signal at the input end of the operational amplifier. The diodes are connected in series, so that the voltage of the reverse end and the same-phase end of the operational amplifier can be simultaneously increased by 1.6V, the differential sampling precision is improved, and the output voltage value of the operational amplifier is not influenced.
And voltage signals at two ends of the sampling resistor enter the differential amplification circuit to be conditioned. The conditioning circuit consists of an operational amplifier and a differential amplifying resistor which are powered by a single power supply. The differential amplification resistor R14 is R28, R11 is R29, and R11 > R14. The operational amplifier output voltage is V.
Fig. 3 is a diagram of a filter circuit and a delay protection circuit, which is composed of two stages of voltage comparator circuits. U1A is the first stage comparing circuit, which compares the current sampling value with the given reference voltage; U1B is a second stage comparator circuit, which compares the output level of the first stage comparator with a given reference voltage.
The reference voltage VH of the first stage comparison circuit is generated by the power supply and reference circuit. The selection of VH needs to be less than the output level of the differential sampling circuit when the fan runs at rated speed and greater than the output level of the differential sampling circuit when the fan runs at short circuit.
The output of an operational amplifier N1A of the differential current detection circuit is a high-frequency sawtooth waveform, and a smooth level signal is output through a low-pass filter circuit consisting of R25 and C7 and is connected to the reverse input end of a first-stage comparator U1A. When the sampling level is greater than the reference level, the comparator outputs a low level; when the sampling level is lower than the reference level, the output end of the comparator is slowly pulled up from 18V through R9, and the capacitor C6 is charged.
The reference voltage of the second stage of the comparison circuit is generated by a zener diode V5. The output of the first comparator U1A is connected to the non-inverting input of the second comparator through the delay charging circuit of R9 and C6. When the output of the first-stage comparator U1A is greater than the reference level, the output end of the second-stage comparator U1B is pulled high by 18V through R12 to output a high level, and a system reports a fault; when the output end of the first-stage comparator U1A is lower than the reference level, the second-stage comparator U1B outputs a low level, and the system is normal.
The heat radiation fan is a controllable fan, the starting mode is soft starting, and the current value of the fan is smaller than the rated current value within a period of starting time. By adjusting the delay charging circuit formed by the R9 and the C6, the rising rate of the level of the in-phase end of the second-stage comparator U1B can be adjusted, and the fan fault is prevented from being mistakenly reported in the starting process.
Claims (5)
1. A direct current fan fault detection circuit is composed of a differential current detection circuit, a filter circuit and a time delay protection circuit; working current of the direct current fan passes through a differential current detection circuit to obtain sampling voltage, the sampling voltage is output to a filter circuit for filtering to obtain a voltage signal proportional to the direct current fan current, the voltage signal is output to a time delay protection circuit to obtain a fault voltage signal of the direct current fan, and fault output is carried out;
the differential current detection circuit consists of an operational amplifier N1A, acquisition resistors R15-R24, rectifier diodes V5-V8, a bypass capacitor C5 and proportional control resistors R11, R14, R28 and R29;
collecting resistors R15-R24 are connected in parallel, collected current of the direct current fan is converted into voltage signals, rectifying diodes V5 and V6 are connected in parallel, V7 and V8 are connected in parallel and then connected in series between the collecting resistors and the ground, the reverse terminal voltage of the operational amplifier N1A is raised, proportional adjusting resistors R14 and R11 are connected with a pin 3 at the same phase end of the operational amplifier N1A, the other end of R14 is connected with one parallel end of the collecting resistors, the other end of R11 is grounded, the proportional adjusting resistors R28 and R29 are connected with a pin 2 at the reverse end of the operational amplifier N1A, the other end of R28 is connected with the other parallel end of the collecting resistors, the other end of R29 is connected with an output pin 1 of the operational amplifier N1A, pin 8 is connected with 18V for power supply, a pin 4 of the operational amplifier N1A is grounded, a pin 8 of the operational amplifier N1A is connected with the ground to form a bypass capacitor C58;
the filter circuit comprises a resistor R25 and a capacitor C7, the output of the differential current detection circuit is connected with the reverse end of a comparator U1A of the delay protection circuit through a resistor R25, and the capacitor C7 is connected between the reverse end of the comparator U1A of the delay protection circuit and the ground;
the time-delay protection circuit consists of a two-stage voltage comparator circuit, wherein a charging circuit consisting of a comparator U1A, a resistor R9 and a capacitor C6 jointly forms a first-stage voltage comparator circuit, a first-stage voltage reference signal VH is connected to the in-phase end of the comparator U1A, a pin 8 of the comparator U1A is connected with 18V for power supply, a pin 4 is grounded, a bypass capacitor C4 is connected between the pin 8 and the ground, one end of the capacitor C6 is connected with a pin 1 of the output end of the comparator U1A, and the other end of the capacitor C6 is grounded; one end of a resistor R9 of the delay protection circuit is connected with a pin 1 at the output end of a comparator U1A, the other end of the resistor R9 is connected with an 18V power supply, a voltage signal which is proportional to the direct current fan current is compared with a voltage reference signal VH by the comparator U1A, the input voltage of the second-stage voltage comparator circuit is obtained, and the capacitor C6 is charged and discharged;
a voltage reference circuit consisting of the comparator U1B, a resistor R10 and a voltage regulator tube V5 jointly forms a second-stage voltage comparator circuit, one end of the resistor R10 of the voltage reference circuit is connected with 18V, and the other end of the resistor R10 of the voltage reference circuit is connected with a reverse end pin 6 of the comparator U1B; the forward end of a voltage regulator tube V5 of the voltage reference circuit is grounded, the reverse end of the voltage regulator tube V5 is connected with the reverse end pin 6 of a comparator U1B, the output end pin 1 of the comparator U1A is connected to the in-phase end pin 5 of the comparator U1B, a pull-up resistor R12 is further connected between the output pin 7 of the comparator U1B and the 18V power supply, the output voltage of the comparator U1A and the regulated voltage of the voltage regulator tube V5 jointly determine the output level signal of the comparator U1B, and if the direct current fan fails, the output level signal of the comparator U1B is at a high level.
2. The dc fan fault detection circuit of claim 1, wherein the dc fan is a low voltage dc fan that has its own hiccup protection capability and does not have more than half of the rated operating current of the fan to flow through the dc fan during a stall fault.
3. The dc fan fault detection circuit of claim 1, wherein the proportional control resistor R14-R28 and R11-R29.
4. A dc fan fault detection circuit as claimed in claim 1 wherein the operational amplifier N1A is a single power supply operational amplifier.
5. The dc fan failure detection circuit of claim 1, wherein the output of the dc fan failure detection circuit is low indicating that the dc fan is operating properly and high indicating that the dc fan is failing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811327895.4A CN109630448B (en) | 2018-11-09 | 2018-11-09 | Direct current fan fault detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811327895.4A CN109630448B (en) | 2018-11-09 | 2018-11-09 | Direct current fan fault detection circuit |
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| Publication Number | Publication Date |
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| CN109630448A CN109630448A (en) | 2019-04-16 |
| CN109630448B true CN109630448B (en) | 2020-06-09 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201811327895.4A Active CN109630448B (en) | 2018-11-09 | 2018-11-09 | Direct current fan fault detection circuit |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110138057B (en) * | 2019-06-27 | 2024-02-02 | 深圳市辉曜科技有限公司 | Solar charger control circuit and solar charger |
| CN112780591B (en) * | 2021-02-25 | 2022-06-07 | 深圳市科元电气技术有限公司 | Fan control and protection circuit and control method of fan protection circuit |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5448143A (en) * | 1993-11-17 | 1995-09-05 | Dell Usa, L.P. | Sensor for monitoring fan operation in a PC or PC based system |
| US6163266A (en) * | 1998-12-08 | 2000-12-19 | Lucent Technologies Inc. | Fan operation detection circuit for a DC fan and method of operation thereof |
| CN101435844A (en) * | 2008-11-14 | 2009-05-20 | 艾默生网络能源有限公司 | Fan failure detection circuit and detection method thereof |
| CN204827996U (en) * | 2015-08-04 | 2015-12-02 | 广东爱迪贝克软件科技有限公司 | Circuit is listened to direct current fan trouble |
| CN107947117A (en) * | 2017-10-23 | 2018-04-20 | 歌尔股份有限公司 | A kind of protection circuit of direct current generator |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000065408A (en) * | 1998-08-19 | 2000-03-03 | Nec Kofu Ltd | Method of detecting fan trouble and its device |
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2018
- 2018-11-09 CN CN201811327895.4A patent/CN109630448B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5448143A (en) * | 1993-11-17 | 1995-09-05 | Dell Usa, L.P. | Sensor for monitoring fan operation in a PC or PC based system |
| US6163266A (en) * | 1998-12-08 | 2000-12-19 | Lucent Technologies Inc. | Fan operation detection circuit for a DC fan and method of operation thereof |
| CN101435844A (en) * | 2008-11-14 | 2009-05-20 | 艾默生网络能源有限公司 | Fan failure detection circuit and detection method thereof |
| CN204827996U (en) * | 2015-08-04 | 2015-12-02 | 广东爱迪贝克软件科技有限公司 | Circuit is listened to direct current fan trouble |
| CN107947117A (en) * | 2017-10-23 | 2018-04-20 | 歌尔股份有限公司 | A kind of protection circuit of direct current generator |
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| CN109630448A (en) | 2019-04-16 |
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