Engine fan controller with electrical isolation

Abstract

The utility model relates to an electrically isolated engine fan controller, belongs to the technical field of fan control, and solves the problem that a fan controller in the prior art cannot meet the requirements of high reliability and electromagnetic compatibility. The engine fan controller provided by the utility model comprises a microcontroller unit, a brush motor fan driving circuit, a control electric filter, a power electric isolation circuit and a first signal isolation circuit, wherein the control electric filter is electrically connected between the control electric input end and the microcontroller unit; the power electricity isolation circuit is electrically connected between the power electricity input end and the brush motor fan driving circuit; the first signal isolation circuit is electrically connected between one PWM output pin of the microcontroller unit and the brush motor fan driving circuit, and the brush motor fan driving circuit is further connected to the power supply end of the brush motor fan. The stability and the safety of the fan controller are improved by connecting the fan controller to a control power supply and increasing universal electrical isolation of the power supply and signals.

Description

Technical Field

[0001] The utility model relates to the technical field of fan controllers, in particular to an electrically isolated engine fan controller. Background Art

[0002] The engine fan controller is a tool used to cool the engine coolant. It can drive the fan to run at different speeds to ensure that coolants of different temperatures are cooled at the lowest power consumption. Engine fan controllers are usually divided into brushless controllers and brushed controllers. Among them, the brushless controller uses PWM control, and the control signal is given by the controller to drive the brushless motor fan to rotate at different speeds, while the brushed controller uses a voltage regulation mode to reduce the speed of the brushed motor fan by adjusting the voltage.

[0003] Existing engine fan controllers generally use power electricity to work, because most devices can stop the fan from working by blowing a fuse in an emergency. However, this controller cannot meet the higher reliability and electromagnetic compatibility requirements of aircraft, ships, rockets, etc. These systems still need undamaged fans to continue to work well in emergency situations. All fans cannot be removed at once, but some fan control circuits need to be shut down for downgraded use to ensure that they can continue to work for 20 minutes after some functions are damaged. Utility Model Content

[0004] In view of the above analysis, the utility model aims to provide an electrically isolated engine fan controller to solve the problem that the fan controller in the prior art cannot meet the requirements of high reliability and electromagnetic compatibility.

[0005] The purpose of this utility model is mainly achieved through the following technical solutions:

[0006] An electrically isolated engine fan controller comprises a microcontroller unit, a brushed motor fan drive circuit, a control electrical filter, a power electrical isolation circuit and a first signal isolation circuit; wherein the control electrical filter is electrically connected between a control electrical input terminal and a power supply pin of the microcontroller unit; the power electrical isolation circuit is electrically connected between a power electrical input terminal and the brushed motor fan drive circuit; the first signal isolation circuit is electrically connected between a PWM output pin of the microcontroller unit and the brushed motor fan drive circuit; and the brushed motor fan drive circuit is also connected to the power supply terminal of the brushed motor fan.

[0007] Furthermore, it also includes a brushless motor fan drive circuit and a second signal isolation circuit; wherein, the second signal isolation circuit is electrically connected between another PWM output pin of the microcontroller unit and the brushless motor fan drive circuit, and the other end of the brushless motor fan drive circuit is connected to the control end of the brushless motor fan.

[0008] Furthermore, the brushed motor fan drive circuit includes a chip SIT2104, a MOS tube Q28, a MOS tube Q29, a resistor R110, a resistor R113, a capacitor C187, a capacitor C188, a Schottky diode D47 and a fuse F18; wherein,

[0009] The IN pin of the chip SIT2104 is connected to the output end of the first signal isolation circuit, and the V cc The pin and SD pin are connected to the output of the power level conversion circuit, and the capacitor C187 is connected to the V cc pin and ground, the positive electrode of Schottky diode D47 is connected to the output end of the power level conversion circuit, the negative electrode is connected to the VB pin of chip SIT2104, the HO pin of chip SIT2104 is connected to the gate of MOS tube Q28 via resistor R110, the LO pin of chip SIT2104 is connected to the gate of MOS tube Q29 via resistor R113, the VS pin of chip SIT2104 is connected to the power supply end of the brush motor fan, and the capacitor C188 is connected between the VS pin of chip SIT2104 and the VB pin of chip SIT2104, the drain of MOS tube Q28 is connected to the output end of the power isolation circuit, the source of MOS tube Q28 is connected to the power supply end of the brush motor fan via fuse F18, the drain of MOS tube Q29 is connected to the power supply end of the brush motor fan, and the source of MOS tube Q29 is grounded;

[0010] The power power level conversion circuit is electrically connected between the power power input terminal and the power power isolation circuit.

[0011] Furthermore, the power electrical isolation circuit includes a common-mode filter and a differential-mode filter circuit; the common-mode filter is ACM90V, and its input terminal pin 1 is connected to the output terminal of the power electrical level conversion circuit, the input terminal pin 2 is grounded, the output terminal pin 4 is connected to one input terminal of the differential-mode filter circuit, and the output terminal pin 3 is connected to the other input terminal of the differential-mode filter circuit; the output terminal of the differential-mode filter circuit is connected to the drain of the MOS tube Q28 of the brushed motor fan drive circuit.

[0012] Further, the differential mode filter circuit includes an inductor L14, an inductor L17, a capacitor C179, a capacitor C158 and a polymer capacitor E10;

[0013] Among them, one end of the inductor L14 is connected to the output terminal 4 pin of the common mode filter, and the other end is connected to the drain of the MOS tube Q28 of the brushed motor fan drive circuit; one end of the inductor L17 is connected to the output terminal 3 pin of the common mode filter, and the other end is grounded; the two ends of the capacitor C179 are respectively connected to one end of the inductor L14 and one end of the inductor L17, and the two ends of the capacitor C158 are respectively connected to the other end of the inductor L14 and the other end of the inductor L17; the positive electrode of the polymer capacitor E10 is connected to the other end of the inductor L14, and the negative electrode is connected to the other end of the inductor L17 and grounded.

[0014] Furthermore, it also includes an output differential mode filter circuit, which is electrically connected between the output end of the brushed motor fan drive circuit and the power supply end of the brushed motor fan.

[0015] Further, the output differential mode filter circuit includes an inductor L16, a capacitor C181, a capacitor C182, a capacitor C183 and a capacitor C184, a polymer capacitor E11, a Schottky diode D45 and a Schottky diode D46;

[0016] Among them, one end of the inductor L16 is connected to the drain of the MOS tube Q29 of the brush motor fan driving circuit, and is connected to the cathode of the Schottky diode D45 and one end of the capacitor C184, and the anode of the Schottky diode D45 and the other end of the capacitor C184 are connected to the ground; the other end of the inductor L16 is connected to the power supply end of the brush motor fan, and is connected to the cathode of the Schottky diode D46, the capacitor C181, the capacitor C182, one end of the capacitor C183 and the anode of the polymer capacitor E11; the anode of the Schottky diode D46, the capacitor C181, the capacitor C182, the other end of the capacitor C183 and the cathode of the polymer capacitor E11 are connected to the ground.

[0017] Furthermore, it also includes a Y capacitor filter component, which includes a Y capacitor C180 and a Y capacitor C185; wherein the positive electrode of the high molecular polymer capacitor E11 of the output differential mode filter circuit is softly connected to the PE shell of the fan controller through the Y capacitor C180; the Y capacitor C185 softly connects the ground to the PE shell of the fan controller.

[0018] Further, the first signal isolation circuit includes a high-speed optical coupling isolation device HCPL-0611, a resistor R111, a resistor R112 and a capacitor C186;

[0019] Among them, pin 2 of the high-speed optocoupler isolation device HCPL-0611 is connected to a PWM output pin of the microcontroller unit through a resistor R111, and pin 3 of the high-speed optocoupler isolation device HCPL-0611 is grounded; pin 7 of the high-speed optocoupler isolation device HCPL-0611 is connected to the IN pin of the chip SIT2104 of the brushed motor fan drive circuit and is grounded through a resistor R112; pin 5 of the high-speed optocoupler isolation device HCPL-0611 is grounded; pin 8 of the high-speed optocoupler isolation device HCPL-0611 is connected to the output end of the power level conversion circuit.

[0020] Furthermore, the second signal isolation circuit includes an optocoupler device TLP293 and a resistor R36; wherein, pin 5 of the optocoupler device TLP293 is connected to another PWM output pin of the microcontroller unit through the resistor R36, and pin 6 of the optocoupler device TLP293 is grounded; pin 12 of the optocoupler device TLP293 is connected to the input end of the brushless motor fan drive circuit, and pin 11 of the optocoupler device TLP293 is grounded.

[0021] Compared with the prior art, the present invention can at least achieve the following beneficial effects:

[0022] 1. The utility model proposes that the control power input power is filtered by the control power filter and then converted to the internal power supply of the fan controller through level conversion. The power input power is connected to the power filter circuit after level conversion to isolate the circuit power supply. On the one hand, when the power fails, the fan controller will not be suspended due to overvoltage, short circuit, interference and other problems, and the drive function will continue to be executed after the power is restored, ensuring the overall stable and efficient operation. On the other hand, by increasing the universal electrical isolation through the control power filter, the power isolation circuit and the first signal isolation circuit, the stability and safety of the fan controller are greatly improved, which can meet the requirements of radiation and conduction.

[0023] 2. It includes a brushed motor fan drive circuit and a brushless motor fan drive circuit, which are compatible with brushed motor fans and brushless motor fans, and meet the fan control of multiple modes such as current limiting and voltage limiting.

[0024] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the following content, and some advantages can be obvious from the description or understood by implementing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the contents specifically pointed out in the text and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components.

[0026] Figure 1 A system structure block diagram of an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a power processing circuit according to an embodiment of the present application;

[0028] Figure 3 This is a diagram of a power electrical isolation circuit, a first signal isolation circuit, and a brushed motor fan drive circuit according to an embodiment of the present application;

[0029] Figure 4 This is an output differential mode filter circuit diagram of an embodiment of the present application;

[0030] Figure 5 This is a diagram of a second signal isolation circuit and a brushless motor fan driving circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0032] A specific embodiment of the utility model discloses an electrically isolated engine fan controller, the overall structure of which is as follows: Figure 1 shown.

[0033] The fan controller includes a microcontroller unit (MCU), a drive circuit and an electrical isolation circuit; the electrical isolation circuit includes a control electrical filter, a brush motor fan drive circuit, a control electrical filter, a power electrical isolation circuit and a first signal isolation circuit; wherein the control electrical filter is electrically connected between the control electrical input terminal and the power pin of the microcontroller unit; the power electrical isolation circuit is electrically connected between the power electrical input terminal and the brush motor fan drive circuit; the first signal isolation circuit is electrically connected between a PWM output pin of the microcontroller unit and the brush motor fan drive circuit; the brush motor fan drive circuit is also connected to the power terminal of the brush motor fan.

[0034] By connecting the fan controller to the control power supply, when the power supply fails, it can be ensured that the fan controller will not suspend operation due to overvoltage, short circuit, interference and other problems, and can continue to perform the driving function after the power supply is restored, ensuring the overall stable and efficient operation; by adding a control electrical filter, the miniaturization characteristics can be ensured while maximizing the optimization of electromagnetic compatibility, and the universal electrical isolation is increased by the power electrical isolation circuit and the first signal isolation circuit, so that the stability and safety of the fan controller are greatly improved, solving the problem that the fan controller of the prior art cannot meet the high reliability and electromagnetic compatibility, and achieving the high requirements of radiation and conduction.

[0035] The isolated signals of the controller are mainly IO signals and PWM signals. Specifically, one PWM output pin of the MCU is connected to the power supply end of the brushed motor fan via the first signal isolation circuit and the brushed motor fan drive circuit; another PWM output pin of the MCU is connected to the control end of the brushless motor fan via the second signal isolation circuit and the brushless motor fan drive circuit; the FO input brushless motor fan feedback signal connected to the brushless motor fan is connected to the IO input pin of the MCU via the IO isolation device, and the high electromagnetic compatibility of the controller is improved through full signal isolation.

[0036] For example, Figure 2 The above is a schematic diagram of the power management circuit of this embodiment. The power input power supply is converted into an internal power supply power supply and a drive circuit power supply power supply by a power level conversion circuit. The control power input power supply is filtered by a control power filter and then passed through an anti-reverse surge circuit, a surge circuit and a control power level conversion circuit. Then, the control power supply is converted into an internal power supply to power the fan controller.

[0037] Furthermore, a Y capacitor is added between the control power supply and the ground to softly connect it to the PE shell of the fan controller. When the voltage difference changes, the AC characteristics of the capacitor are utilized to ensure that there is no large voltage difference between the two power supplies before and after the Y capacitor. By designing the PE isolation shell, electromagnetic compatibility radiation is further reduced.

[0038] For example, Figure 3 As described above, the brushed motor fan driving circuit of this embodiment includes a chip SIT2104, a MOS tube Q28, a MOS tube Q29, a resistor R110, a resistor R113, a capacitor C187, a capacitor C188, a Schottky diode D47 and a fuse F18;

[0039] The IN pin of the chip SIT2104 is connected to the output end of the first signal isolation circuit, and the V cc The pin and SD pin are connected to the output of the power level conversion circuit, and the capacitor C187 is connected to the Vcc pin and ground, the positive electrode of Schottky diode D47 is connected to the output end of the power level conversion circuit, the negative electrode is connected to the VB pin of chip SIT2104, the HO pin of chip SIT2104 is connected to the gate of MOS tube Q28 via resistor R110, the LO pin of chip SIT2104 is connected to the gate of MOS tube Q29 via resistor R113, the VS pin of chip SIT2104 is connected to the power supply end of the brush motor fan, and the capacitor C188 is connected between the VS pin of chip SIT2104 and the VB pin of chip SIT2104, the drain of MOS tube Q28 is connected to the output end of the power isolation circuit, the source of MOS tube Q28 is connected to the power supply end of the brush motor fan via fuse F18, the drain of MOS tube Q29 is connected to the power supply end of the brush motor fan, and the source of MOS tube Q29 is grounded;

[0040] For example, Figure 3 As described in Part A, the power electrical isolation circuit of this embodiment includes a common-mode filter and a differential-mode filter circuit; the common-mode filter is ACM90V, and its input terminal pin 1 is connected to the output terminal of the power electrical level conversion circuit, the input terminal pin 2 is grounded, the output terminal pin 4 is connected to one input terminal of the differential-mode filter circuit, and the output terminal pin 3 is connected to the other input terminal of the differential-mode filter circuit; the output terminal of the differential-mode filter circuit is connected to the drain of the MOS tube Q28 of the brushed motor fan drive circuit.

[0041] The differential mode filter circuit includes an inductor L14, an inductor L17, a capacitor C179, a capacitor C158 and a polymer capacitor E10;

[0042] Among them, one end of the inductor L14 is connected to the output terminal 4 pin of the common mode filter, and the other end is connected to the drain of the MOS tube Q28 of the brushed motor fan drive circuit; one end of the inductor L17 is connected to the output terminal 3 pin of the common mode filter, and the other end is grounded; the two ends of the capacitor C179 are respectively connected to one end of the inductor L14 and one end of the inductor L17, and the two ends of the capacitor C158 are respectively connected to the other end of the inductor L14 and the other end of the inductor L17; the positive electrode of the polymer capacitor E10 is connected to the other end of the inductor L14, and the negative electrode is connected to the other end of the inductor L17 and grounded.

[0043] The power isolation circuit implements power supply and ground filtering to ensure that when the bidirectional MOS is turned on, the short circuit between the output and the ground will not cause the ground level to rise and cause the overall transmission to rise.

[0044] In order to improve electromagnetic compatibility, a higher PWM frequency is required for a brushed motor fan with voltage regulation control. For example, Figure 3As shown in part B, a high-speed optocoupler isolator HCPL-0611 is selected for PWM control signal isolation. Pin 2 of the high-speed optocoupler isolation device is connected to a PWM output pin of the microcontroller unit through a resistor R111, and pin 3 of the device is connected to the ground; pin 7 of the device is connected to the IN pin of the chip SIT2104 of the brushed motor fan drive circuit, pin 5 of the device is connected to the isolated signal ground, and the power supply of the device is connected to the output end of the power level conversion circuit.

[0045] Furthermore, an output differential mode filter circuit is added between the output end of the drive circuit of the brushed motor fan and the power supply end of the brushed motor fan.

[0046] like Figure 4 As shown, the output differential mode filter circuit includes an inductor L16, a capacitor C181, a capacitor C182, a capacitor C183, a capacitor C184, a polymer capacitor E11, a Schottky diode D45 and a Schottky diode D46;

[0047] Among them, one end of the inductor L16 is connected to the drain of the MOS tube Q29 of the brush motor fan driving circuit, and is connected to the cathode of the Schottky diode D45 and one end of the capacitor C184, and the anode of the Schottky diode D45 and the other end of the capacitor C184 are connected to the ground; the other end of the inductor L16 is connected to the power supply end of the brush motor fan, and is connected to the cathode of the Schottky diode D46, the capacitor C181, the capacitor C182, one end of the capacitor C183 and the anode of the polymer capacitor E11; the anode of the Schottky diode D46, the capacitor C181, the capacitor C182, the other end of the capacitor C183 and the cathode of the polymer capacitor E11 are connected to the ground.

[0048] The output end of the output differential mode filter circuit also includes a Y capacitor filter component, and the Y capacitor filter includes a Y capacitor C180 and a Y capacitor C185; wherein, the positive electrode of the high molecular polymer capacitor E11 of the output differential mode filter circuit is softly connected to the PE shell of the fan controller through the Y capacitor C180; the Y capacitor C185 softly connects the ground to the PE shell of the fan controller.

[0049] The output differential mode filter is added to the output end of the brushed drive motor fan, and the stability of power output is ensured by inductor and capacitor filtering. When the voltage difference changes, the Y capacitor filter uses the AC characteristics of the capacitor to make the two power supplies before and after the filter capacitor have no large voltage difference, and softly connects with the PE isolation shell to further reduce electromagnetic compatibility radiation.

[0050] For example, Figure 5As shown, the second signal isolation circuit includes an optocoupler device TLP293 and a resistor R36; wherein, pin 5 of the optocoupler device TLP293 is connected to another PWM output pin of the microcontroller unit through the resistor R36, and pin 6 of the optocoupler device TLP293 is grounded; pin 12 of the optocoupler device TLP293 is connected to the input end of the brushless motor fan drive circuit, and pin 11 of the optocoupler device TLP293 is grounded.

[0051] The driving circuit of the brushless motor fan includes resistors R43, R48, R51 and R56, a diode D8 and a transistor Q8; wherein the base of the transistor Q8 is connected to the output end of the second signal isolation circuit through the resistor R43, the emitter of the transistor Q8 is connected to the power supply through R56, the collector of the transistor Q8 is grounded through the resistor R48, the resistor R51 is connected in parallel to the base and emitter of the transistor Q8, the cathode of the diode D8 is connected to the emitter of the transistor Q8, and the positive electrode is grounded.

[0052] The optocoupler TLP293 is used as the primary diode, and the transistor Q8 is used as the secondary amplifier of the driver to output a larger current to meet the needs of PWM brushless motor fan driving. This not only ensures isolation, but also drives the subsequent circuit well and has good electromagnetic compatibility.

[0053] Compared with the prior art, this embodiment proposes that the control power input power is filtered by the control power filter, and then the control power is converted into the internal power supply of the fan controller by the level conversion circuit. The power input power is connected to the power filter circuit after level conversion, and is used to supply power to the isolation circuit. On the one hand, when the power fails, the fan controller will not suspend operation due to overvoltage, short circuit, interference and other problems, and then continue to perform the driving function after the power is restored, ensuring the overall stable and efficient operation. On the other hand, universal electrical isolation is added by controlling the electric filter, the power isolation circuit and the first signal isolation circuit, so that the stability and safety of the fan controller are greatly improved, and the requirements of radiation and conduction can be met. The design of the brushed motor fan drive and the brushless motor fan drive is compatible with the control of the brushed motor fan and the brushless motor fan, meeting the fan control of multiple modes such as current limiting and voltage limiting.

[0054] The above is only a preferred specific implementation of this embodiment, but the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be covered by the protection scope of the present invention.

Claims

1. An electrically isolated engine fan controller, characterized in that: The controller includes a microcontroller unit, a brushed motor fan drive circuit, a control electric filter, a power electric isolation circuit and a first signal isolation circuit; wherein, The control electrical filter is electrically connected between the control electrical input terminal and the power pin of the microcontroller unit; the power electrical isolation circuit is electrically connected between the power electrical input terminal and the brushed motor fan drive circuit; the first signal isolation circuit is electrically connected between a PWM output pin of the microcontroller unit and the brushed motor fan drive circuit; the brushed motor fan drive circuit is also connected to the power terminal of the brushed motor fan.

2. An electrically isolated engine fan controller according to claim 1, characterized in that: It also includes a brushless motor fan drive circuit and a second signal isolation circuit; wherein the second signal isolation circuit is electrically connected between another PWM output pin of the microcontroller unit and the brushless motor fan drive circuit, and the other end of the brushless motor fan drive circuit is connected to the control end of the brushless motor fan.

3. The electrically isolated engine fan controller according to claim 1, characterized in that: The brushed motor fan drive circuit includes a chip SIT2104, a MOS tube Q28, a MOS tube Q29, a resistor R110, a resistor R113, a capacitor C187, a capacitor C188, a Schottky diode D47 and a fuse F18; wherein, The IN pin of the chip SIT2104 is connected to the output end of the first signal isolation circuit, and the V cc The pin and SD pin are connected to the output of the power level conversion circuit, and the capacitor C187 is connected to the V cc pin and ground, the positive electrode of Schottky diode D47 is connected to the output end of the power level conversion circuit, the negative electrode is connected to the VB pin of chip SIT2104, the HO pin of chip SIT2104 is connected to the gate of MOS tube Q28 via resistor R110, the LO pin of chip SIT2104 is connected to the gate of MOS tube Q29 via resistor R113, the VS pin of chip SIT2104 is connected to the power supply end of the brush motor fan, and the capacitor C188 is connected between the VS pin of chip SIT2104 and the VB pin of chip SIT2104, the drain of MOS tube Q28 is connected to the output end of the power isolation circuit, the source of MOS tube Q28 is connected to the power supply end of the brush motor fan via fuse F18, the drain of MOS tube Q29 is connected to the power supply end of the brush motor fan, and the source of MOS tube Q29 is grounded; The power power level conversion circuit is electrically connected between the power power input terminal and the power power isolation circuit.

4. The electrically isolated engine fan controller according to claim 3, characterized in that: The power electrical isolation circuit includes a common mode filter and a differential mode filter circuit; the common mode filter is ACM90V, its input terminal pin 1 is connected to the output terminal of the power electrical level conversion circuit, the input terminal pin 2 is grounded, the output terminal pin 4 is connected to one input terminal of the differential mode filter circuit, and the output terminal pin 3 is connected to the other input terminal of the differential mode filter circuit; the output terminal of the differential mode filter circuit is connected to the drain of the MOS tube Q28 of the brushed motor fan drive circuit.

5. The electrically isolated engine fan controller according to claim 4, characterized in that: The differential mode filter circuit includes an inductor L14, an inductor L17, a capacitor C179, a capacitor C158 and a polymer capacitor E10; Among them, one end of the inductor L14 is connected to the output terminal 4 pin of the common mode filter, and the other end is connected to the drain of the MOS tube Q28 of the brushed motor fan drive circuit; one end of the inductor L17 is connected to the output terminal 3 pin of the common mode filter, and the other end is grounded; the two ends of the capacitor C179 are respectively connected to one end of the inductor L14 and one end of the inductor L17, and the two ends of the capacitor C158 are respectively connected to the other end of the inductor L14 and the other end of the inductor L17; the positive electrode of the polymer capacitor E10 is connected to the other end of the inductor L14, and the negative electrode is connected to the other end of the inductor L17 and grounded.

6. The electrically isolated engine fan controller according to claim 3, characterized in that: It also includes an output differential mode filter circuit, which is electrically connected between the output end of the brushed motor fan drive circuit and the power supply end of the brushed motor fan.

7. An electrically isolated engine fan controller according to claim 6, characterized in that: The output differential mode filter circuit includes an inductor L16, a capacitor C181, a capacitor C182, a capacitor C183, a capacitor C184, a polymer capacitor E11, a Schottky diode D45 and a Schottky diode D46; Among them, one end of the inductor L16 is connected to the drain of the MOS tube Q29 of the brush motor fan driving circuit, and is connected to the cathode of the Schottky diode D45 and one end of the capacitor C184, and the anode of the Schottky diode D45 and the other end of the capacitor C184 are connected to the ground; the other end of the inductor L16 is connected to the power supply end of the brush motor fan, and is connected to the cathode of the Schottky diode D46, the capacitor C181, the capacitor C182, one end of the capacitor C183 and the anode of the polymer capacitor E11; the anode of the Schottky diode D46, the capacitor C181, the capacitor C182, the other end of the capacitor C183 and the cathode of the polymer capacitor E11 are connected to the ground.

8. An electrically isolated engine fan controller according to claim 7, characterized in that: It also includes a Y capacitor filter component, which includes a Y capacitor C180 and a Y capacitor C185; wherein the positive electrode of the high molecular polymer capacitor E11 of the output differential mode filter circuit is softly connected to the PE shell of the fan controller through the Y capacitor C180; the Y capacitor C185 softly connects the ground to the PE shell of the fan controller.

9. The electrically isolated engine fan controller according to claim 3, characterized in that: The first signal isolation circuit includes a high-speed optical coupler isolation device HCPL-0611, a resistor R111, a resistor R112 and a capacitor C186; Among them, pin 2 of the high-speed optocoupler isolation device HCPL-0611 is connected to a PWM output pin of the microcontroller unit through a resistor R111, and pin 3 of the high-speed optocoupler isolation device HCPL-0611 is grounded; pin 7 of the high-speed optocoupler isolation device HCPL-0611 is connected to the IN pin of the chip SIT2104 of the brushed motor fan drive circuit and is grounded through a resistor R112; pin 5 of the high-speed optocoupler isolation device HCPL-0611 is grounded; pin 8 of the high-speed optocoupler isolation device HCPL-0611 is connected to the output end of the power level conversion circuit.

10. The electrically isolated engine fan controller according to claim 2, characterized in that: The second signal isolation circuit includes an optocoupler device TLP293 and a resistor R36; wherein, pin 5 of the optocoupler device TLP293 is connected to another PWM output pin of the microcontroller unit through the resistor R36, and pin 6 of the optocoupler device TLP293 is grounded; pin 12 of the optocoupler device TLP293 is connected to the input end of the brushless motor fan drive circuit, and pin 11 of the optocoupler device TLP293 is grounded.

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