Claims:
1. A system configured in an electrical device comprising:
a cooling fan;
a digital signal processor (DSP) configured to issue a fan control signal to an isolation unit, wherein the fan control signal varies based on speed of the cooling fan depending on temperature of the system;
a MOSFET device configured to receive the fan control signal from the isolation unit, and further configured to vary MOSFET device current based on said fan control signal;
a comparison circuit configured to continuously receive and compare the varying MOSFET device current with a reference signal and enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
2. The system of claim 1, wherein the fan control signal is received by the MOSFET device using a gate drive and clamping circuit.
3. The system of claim 1, wherein the varying MOSFET device current is amplified before the comparison.
4. The system of claim 1, wherein the reference signal is received from a human machine interface (HMI) circuit or from a divider circuit or from a hardware circuit.
5. The system of claim 1, wherein the reference signal is communicated from RS485 medium.
6. The system of claim 1, wherein the cooling fan is healthy when the fan control signal is active low.
7. The system of claim 1, wherein the system is shut down when the fan control signal is active high.
8. A method comprising the steps of:
receiving, at an isolation unit of a fan protection module that is configured in an electrical device and is operatively coupled with a cooling fan, a fan control signal that varies based on speed of the cooling fan depending on temperature of the system;
transmitting, to a MOSFET device configured in the fan protection module and operatively coupled with the isolation unit, the fan control signal, wherein MOSFET device current is varied based on the fan control signal; and
comparing, at a comparison circuit of the fan protection module, the varying MOSFET device current with a reference signal so as to enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
9. The method of claim 8, wherein the fan control signal is received by the MOSFET device using a gate drive and clamping circuit.
10. The method of claim 8, wherein the reference signal is received from a human machine interface (HMI) circuit or from a divider circuit or from a hardware circuit.

, Description:
TECHNICAL FIELD
[0001] The present disclosure generally relates to the field offault detection of electrical devices. In particular, the present disclosure pertains tofault detection systems for cooling fans.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Cooling fans are typically used for thermal management of heat trapped in electrical/electronic devices such as in Low Voltage (LV) drives. Various electrical and electronic devices employ a cooling fan to cool heat generated by the devices when they operate. Such devices typically consist of information processors such as a computer, office automation (OA) appliances, home electronic appliances, electric power equipment, and so on. Typically, the motor shaft rotation rate and the cooling fan airflow rate are determined in consideration of the expected temperature of the device.As cooling fansare among the most vulnerable and critical parts in such devices, and can affect power handling capacity of the devices, if the fan fails, it tries to draw more current or trips/fails the power supply of the device/system which blocks switching of the inverter powering the motor-load system. There is therefore protection needed for the cooling fan and for other components of devices/drives in which the fan is configured because in case of a problem in the power supply that supplies control voltage to fan for its operation, the problem can also affect other components if the fan is shorted or unhealthy and also if fan is clogged due to dust.
[0004] There is therefore a need for a fault detection and prevention system that solves the above-mentioned problems.
[0005] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0006] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0007] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0008] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0009] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

OBJECTS OF THE INVENTION
[0010] An object of the present disclosure is to enable efficient fan isolation and fan fault detection.
[0011] Another object of the present disclosure is to enable use of a combination of hardware and software for fan fault detection.

SUMMARY
[0012] The present disclosure generally relates to the field of fault detection of electrical devices. In particular, the present disclosure pertains to fault detection systems for cooling fans.
[0013] The present disclosure relates to a fan protection module (also interchangeably referred to as a “system” hereinafter) configured in an electrical device, wherein the fan protection module is operatively coupled a cooling fan and comprises a digital signal processor (DSP) configured to issue a fan control signal to an isolation unit, wherein the fan control signal varies based on speed of the cooling fan depending on temperature of the system, a MOSFET device configured to receive the fan control signal from the isolation unit, and further configured to vary MOSFET device current based on the fan control signal, and a comparison circuit configured to continuously receive and compare the varying MOSFET device current with a reference signal and enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
[0014] In an aspect, the fan control signal can be received by the MOSFET device using a gate drive and clamping circuit. In another aspect, the varying MOSFET device current can be amplified before the comparison. In another aspect, the reference signal can be received from a human machine interface (HMI) circuit or from a divider circuit or from a hardware circuit, the reference signal can be communicated from RS485 medium.
[0015] In an aspect, the cooling fan can be healthy when the fan control signal is active low. In another aspect, the system can be shut down when the fan control signal is active high.
[0016] The present disclosure further relates to a method comprising the steps of: receiving, at an isolation unit of a fan protection module that is configured in an electrical device which in turn is operatively coupled with a cooling fan, a fan control signal that varies based on speed of the cooling fan depending on temperature of the system; transmitting, to a MOSFET device (of the fan protection module) that is operatively coupled with the isolation unit, the fan control signal, wherein MOSFET device current is varied based on the fan control signal; and comparing, at a comparison circuit (of the fan protection module) that is operatively coupled with the fan protection module, the varying MOSFET device current with a reference signal so as to enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
[0017] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components

BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0019] FIG.1 illustrates an exemplary Low Voltage (LV) drive comprising a fan protection module in which aspects of the present disclosure can be implemented.
[0020] FIG. 2 illustrates exemplary constructional details of the proposed fan protection module in which aspects of the present disclosure can be implemented.
[0021] FIG. 3 illustrates an exemplary flow diagram showing working of the proposed fan protection module in accordance with an embodiment of the present disclosure

DETAILED DESCRIPTION
[0022] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0023] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0024] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0025] The present disclosure generally relates to the field of fault detection of electrical devices. In particular, the present disclosure pertains to fault detection systems for cooling fans.
[0026] The present disclosure relates to a fan protection module (also interchangeably referred to as a “system” hereinafter) configured in an electrical device, wherein the fan protection module is operatively coupled a cooling fan and comprises a digital signal processor (DSP) configured to issue a fan control signal to an isolation unit, wherein the fan control signal varies based on speed of the cooling fan depending on temperature of the system, a MOSFET device configured to receive the fan control signal from the isolation unit, and further configured to vary MOSFET device current based on the fan control signal, and a comparison circuit configured to continuously receive and compare the varying MOSFET device current with a reference signal and enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
[0027] In an aspect, the fan control signal can be received by the MOSFET device using a gate drive and clamping circuit. In another aspect, the varying MOSFET device current can be amplified before the comparison. In another aspect, the reference signal can be received from a human machine interface (HMI) circuit or from a divider circuit or from a hardware circuit, the reference signal can be communicated from RS485 medium.
[0028] In an aspect, the cooling fan can be healthy when the fan control signal is active low. In another aspect, the system can be shut down when the fan control signal is active high.
[0029] The present disclosure further relates to a method comprising the steps of: receiving, at an isolation unit of a fan protection module that is configured in an electrical device which in turn is operatively coupled with a cooling fan, a fan control signal that varies based on speed of the cooling fan depending on temperature of the system; transmitting, to a MOSFET device (of the fan protection module) that is operatively coupled with the isolation unit, the fan control signal, wherein MOSFET device current is varied based on the fan control signal; and comparing, at a comparison circuit (of the fan protection module) that is operatively coupled with the fan protection module, the varying MOSFET device current with a reference signal so as to enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
[0030] FIG. 1 illustrates an exemplary Low Voltage (LV) drive 100 comprising a fan protection module 102 in which aspects of the present disclosure can be implemented. As can be seen, drive 100 can include, in a non-limiting manner, a power supply module 104, a gate driver module 106, a control mechanism 108 for motor 114, an input grid 120, an induction motor load 122a and 122b, a solar panel 118, and a pump 116 run by the motor 114. As would be appreciated, although aspects of the present disclosure have been explained with respect to an LV drive coupled with a motor that is configured to drive a pump, such an architecture is completely exemplary in nature and any other application of the proposed fan protection module 102 can be implemented, all of which potential applications, configurations, and constructions are completely within the scope of the present disclosure. Any other application of the proposed LV drive that incorporates the proposed fan protection module 102 is therefore well within the scope of the present disclosure. In an aspect, LV drive of the present disclosure can be configured for motor control and can have applications in multiple industries such as textiles, agriculture, elevator, etc.
[0031] It would be appreciated that cooling fan of the present disclosure can be used for thermal management of heat trapped in the drive, wherein speed of the cooling fan can be controlled as per the temperature of the heat sink. Cooling fan is among the most vulnerable and critical parts of a drive and can affect power handling capacity of the drive. If fan fails, it tries to draw more current or will trip/fail the power supply of the drive system which will block the switching of the inverter powering the motor-load system. Therefore, the constructions of the present disclosure, specially the module 102 help isolate the fan in case of fan fault and intimate the control system regarding the same.
[0032] FIG. 2 illustrates exemplary constructional details of the proposed fan protection module 102 in which aspects of the present disclosure can be implemented.
[0033] In an exemplary embodiment, fan protection module 102 (also interchangeably referred to as a “system 102” hereinafter) can be configured in an electrical device such as LV drive 100 of FIG. 1, wherein the fan protection module 102 can be operatively coupled with a cooling fan 202 and can include a digital signal processor (DSP) configured to issue a fan control signal 204 to an isolation unit 206, wherein the fan control signal 204 varies based on speed of the cooling fan depending on temperature of the system 112, a MOSFET device 210 configured to receive the fan control signal from the isolation unit 206, and further configured to vary MOSFET device current based on the fan control signal, and a comparison circuit 212 configured to continuously receive and compare the varying MOSFET device current with a reference signal and enable issuance of a trip signal to the device when the reference signal is lower than the varying MOSFET device current for a defined time period.
[0034] In an aspect, the fan control signal can be received by the MOSFET device 210 using a gate drive and clamping circuit 208. In another aspect, the varying MOSFET device current can be amplified before the comparison. In another aspect, the reference signal can be received from a human machine interface (HMI) circuit 214 or from a divider circuit 214 or from a hardware circuit 214, wherein the reference signal can be communicated from RS485 medium.
[0035] In an aspect, the cooling fan 202 can be healthy when the fan control signal is active low. In another aspect, the system can be shut down when the fan control signal is active high.
[0036] As shown in FIG.1, power supply module can be configured to provide control power supply to fan module apart from other power supplies. Fan protection module 102 can be configured to disable fan control signal i.e. FAN PWM (pulse width modulation) when high load current transients or continuous current is detected. Disabled fan control signal can be intimated to the DSP, enabling the DSP to shut down the pulse till the user intervention which calls for fan service.
[0037] Again, with reference to FIG. 2, fan protection module 102 can enable fan control signal to be issued by DSP to an isolation unit/circuit as a PWM controlled signal, wherein speed of the fan can be varied depending on temperature of the system.? At the isolation unit, the fan control signal can be isolated and powered to MOSFET device using a gate drive and/or clamping circuits. MOSFET device current can then be continuously monitored and amplified for comparison at a comparison circuit with a reference signal, wherein the reference signal can be provided by HMI with the drive (also referred to as reference circuit) i.e. communicated through RS485 medium. Also, the reference signal can be provided through a hardware circuit such that when RMS current of the device exceeds the fan current over a specified interval of time and/or if the fault occurs for a defined number of times (i.e. the fan control signal is active with fault), the DSP unit can count the number of occurrences and consequently trip the inverter to shut off/down the switching signal to the inverter, making the motor stop.? In an aspect, the reference circuit can be configured to providethe reference signal to the comparison circuit that detects present current threshold of the device and provides a command to switch off the fan and also gives active high valuefor the fan control signal to the DSP.
[0038] In an aspect, as also shown in FIG.2, the present disclosure takes into consideration fan control signal along with thermal feedback, making the proposed fan protection module 102 as a fool-proof arrangement for fan protection by isolating the entire power supply from powering fan.
[0039] The present invention therefore facilitates user to get intimated or alarmed or signal in situation wherein the fan is faulty, fan rotor is clogged due to dust or blockage, and hence if fan is shorted it will try to draw more power from the main power supply and hence disrupt the entire system control power supply section. Thus detecting this condition and asking user to shut down the drive system as fan is faulty and user should go for fan service.
[0040] FIG. 3 illustrates an exemplary flow diagram 300 showing working of the proposed fan protection module 102 in accordance with an embodiment of the present disclosure. At step 302 of the proposed method, drive/electrical device of the present disclosure can be given a start command, post which, at step 304, fan control signal can be evaluated for a defined period of time as to if it is healthy i.e. active low such that if the signal is not healthy, at step 306, the system is shut down due to the signal being active high and the user can be intimated about the device/system status. On the other hand, if step 304 indicates that the fan control signal is healthy i.e. active low, at step 308, the signal can be given to an isolation unit which passes it onto a MOSFET (metal–oxide–semiconductor field-effect transistor)device through a gate drive and clamping circuit. At step 310, a comparison circuit (also referred to as a comparator circuit or simply as comparator) can be used to continuously compare MOSFET device current that varies based on the received fan control signal with a reference current/signal such that if the MOSFET device current is below the reference signal for a defined amount of time, at step 312, the fan can be evaluated as being healthy else at step 314, the system can be shut down at step 306 through issuance of a trip signal.
[0041] In an aspect, the proposed technique trips the system through hardware and also intimates to user that Fan needs corrective action in order to start the drive for motor control. ?In an aspect, as shown above, the proposed fan protection module can be configured as part of the LV drive /Solar drive system in order to enhance life of system by way of increasing life of fan through the fan protection module and also intimating to user that FAN service is required and by stopping the drive intentionally on occurrence of fan fault. ?The present disclosure therefore provides efficient fan isolation and fan fault detection Intimation to control circuitry for fan fault. Implementation of the system using hardware and software intelligence further enhances the robustness of the proposed architecture.
[0042] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0043] The present disclosure enables efficient fan isolation and fan fault detection.
[0044] The present disclosure enables use of a combination of hardware and software for fan fault detection.