High reliability propeller de-icing controller

Abstract

This invention belongs to the field of de-icing technology and discloses a high-reliability propeller electric de-icing controller, including a lightning protection circuit, a voltage spike circuit, a linear voltage regulator circuit, a timing generation circuit, and an output control circuit. The input and output interfaces are connected to other circuits through the lightning protection circuit. The input interface is also connected in series with the voltage spike circuit. The linear voltage regulator circuit provides power to the downstream timing generation circuit. The control waveform output by the timing generation circuit controls the output control circuit, which converts the DC power input from the aircraft into a heating power supply with a 90s on and 90s off cycle. This invention can withstand lightning induction tests of level A3G3L3, withstand voltage spikes of 600V 10µs, and withstand surges of 80V 50ms, exhibiting high reliability and high precision.

Description

A high-reliability propeller electric de-icing controller Technical Field

[0001] This invention belongs to the field of de-icing technology and relates to a propeller de-icing device, specifically a high-reliability propeller electric de-icing controller. Background Technology

[0002] Under specific climatic conditions, icing often occurs on the windward surfaces of aircraft flying at high altitudes. As ice accumulates, its thickness and mass increase. While ice at the edges of the propeller blades can be ejected, ice at the base of the propeller cannot. Propeller icing can lead to aircraft instability or insufficient thrust, affecting flight missions and safety. Electro-de-icing is the most common method for propeller de-icing and is widely used in military and civilian aircraft propellers.

[0003] Foreign de-icing timers use relays to control the on / off state of the 28V DC heating power supply on the aircraft, thus achieving intermittent heating of the propeller. However, relays have low reliability; using relays under such high current conditions can easily cause the relay contacts to melt, resulting in a constantly on fault in the de-icing timer, damaging the aircraft propeller and affecting flight missions and aircraft safety. Research revealed that this de-icing timer has a high failure rate, with constantly on faults caused by melted relay contacts being the most frequent. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a highly reliable propeller electric de-icing controller, which achieves high reliability compared to similar de-icing timers from abroad.

[0005] The technical solution of the present invention is as follows:

[0006] A high-reliability propeller electric de-icing controller includes a lightning protection circuit, a voltage spike circuit, a linear voltage regulator circuit, a timing generator circuit, and an output control circuit. The input and output interfaces are connected to other circuits via the lightning protection circuit. The input interface is also connected in series with the voltage spike circuit. The linear voltage regulator circuit provides power to the downstream timing generator circuit. The control waveform output by the timing generator circuit controls the output control circuit, which converts the DC power input from the propeller into a heating power supply that operates on for 90 seconds and off for 90 seconds.

[0007] Furthermore, the timing generation circuit is dual-channel. The dual-channel timing generation circuit is controlled to have the same timing through a phase synchronization circuit. The control waveforms output by the two timing generation circuits control the two output control circuits respectively.

[0008] Furthermore, the linear regulator circuit includes a linear regulator to convert the 28V power supply voltage to 5V. The linear regulator is a linear regulator with a wide input voltage range, ensuring that the regulator circuit can still operate normally when there is an 80V overvoltage surge. The input terminal of the linear regulator circuit is equipped with a diode to provide reverse connection protection.

[0009] Furthermore, pin 5 of the linear regulator is connected to one end of resistor R201, and pins 3 and 4 of the linear regulator circuit are connected to the other end of resistor R201 and the output terminal. Pin 5 of the linear regulator circuit is also grounded through resistor R203. The output voltage of the linear regulator circuit is adjusted by adjusting the voltage across resistors R201 and R203, specifically as follows:

[0010]

[0011] Among them, V ref It is the reference voltage, I ADJ This is the current at pin 5 of the linear regulator.

[0012] Furthermore, the linear regulator circuit is dual-channel. The dual-channel linear regulator circuit uses diodes to perform an "OR" operation, providing a stable power supply to the downstream timing generation circuit. The dual-channel linear regulator circuit includes linear regulator M210 and linear regulator M211. The output terminals of linear regulator M210 and linear regulator M211 are connected together using Schottky diode V201 and Schottky diode V202, respectively.

[0013] Furthermore, to prevent transient voltage spikes from the ground line, a diode V214 is used to isolate the ground line of the timing generation circuit from the output ground line of the linear regulator circuit.

[0014] Furthermore, the timing generation circuit generates a control waveform with a 90s high level and a 90s low level. Specifically, it includes an RC oscillation circuit and a frequency divider circuit. When chip M201 is powered on, because pin 9 of chip M201 is connected to a high level, the initial output of chip M201 is a high level. The RC oscillation circuit includes resistors R220 and R230, and capacitors C240 ​​and C241. The charging and discharging of capacitors C240 ​​or C241 by resistors R220 and R230 generates a clock signal of a certain frequency. Resistors R220 and R230 are connected to pin 1 of chip M201, and capacitors C240 ​​or C241 are connected to pin 2 of chip M201. By calculating the value of RC, pin 8 of chip M201 can output a control signal with a period of 90s high level and 90s low level. The rear end of pin 8 of chip M201 is connected to a follower circuit composed of operational amplifier M230.

[0015] Furthermore, the circuit period of the RC oscillator circuit is:

[0016]

[0017] Ground pins 12 and 13 of chip M201, set the frequency divider to 2^13, and the timing circuit output period is... Therefore, the period of the RC oscillator circuit is:

[0018]

[0019] Calculate the parameters of the RC oscillator circuit

[0020]

[0021] C240 and C241 are 100nF.

[0022]

[0023] Therefore, the resistance values ​​are: R220 is 191kΩ, and R230 is 66.5Ω.

[0024] Furthermore, the output control circuit uses an ideal diode driver chip M220 to convert the on-machine voltage into a heating power supply that is turned on for 90 seconds and turned off for 90 seconds. The ideal diode chip drives two back-to-back N-channel field-effect transistors Q201 and Q202 to achieve the on / off control of the output.

[0025] Furthermore, the two output control circuits serve as backups for each other, and their output terminals are connected to form an "OR" circuit.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. This invention incorporates lightning protection design, enabling it to withstand lightning induction tests of level A3G3L3;

[0028] 2. This invention incorporates a voltage spike design, enabling it to withstand a 600V 10µs voltage spike;

[0029] 3. This invention adopts a wide input voltage range design and can withstand an 80V 50ms surge;

[0030] 4. This invention uses a MOSFET instead of a relay to control the on / off state of the heating power supply, thus improving reliability;

[0031] 5. This invention adopts a high-precision timing circuit design to achieve the function of powering on for 90 seconds and turning off for 90 seconds, with an accuracy of ±1 second;

[0032] 6. This invention features a dual-redundancy design. Under normal circumstances, the dual-redundancy circuits operate simultaneously, which can reduce power consumption. When one of the circuits fails, the remaining circuit operates independently, resulting in extremely high reliability.

[0033] 7. This invention uses fewer components, has high reliability, an MTBF of up to 140,000 hours, and a normal-on output failure probability of 2.87 × 10⁻⁶. -7 The probability of a no-output fault is 1.21 × 10⁻⁶. -7 . Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this invention, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 is a schematic diagram of a high-reliability propeller electro-de-icing controller according to an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of the linear voltage regulator circuit in a high-reliability propeller electric de-icing controller according to an embodiment of the present invention;

[0037] Figure 3 is a schematic diagram of the timing generation circuit in a high-reliability propeller electric de-icing controller according to an embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of the output control circuit in a high-reliability propeller electro-de-icing controller according to an embodiment of the present invention;

[0039] Figure 5 is a structural diagram of a high-reliability propeller electro-de-icing controller according to an embodiment of the present invention. Detailed Implementation

[0040] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0041] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are given in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integrated connection; they can refer to a mechanical connection or a point connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] A high-reliability propeller electric de-icing controller includes a lightning protection circuit, a voltage spike circuit, a linear voltage regulator circuit, a timing generator circuit, and an output control circuit. The input and output interfaces are connected to other circuits via the lightning protection circuit. The input interface is also connected in series with the voltage spike circuit. The linear voltage regulator circuit provides power to the downstream timing generator circuit. The control waveform output by the timing generator circuit controls the output control circuit, which converts the DC power input from the propeller into a heating power supply that operates on for 90 seconds and off for 90 seconds.

[0044] The timing generation circuit is dual-channel. The timing generation circuits are controlled to have the same timing through a phase synchronization circuit. The control waveforms output by the two timing generation circuits control the two output control circuits respectively.

[0045] The linear regulator circuit includes a linear regulator to convert the 28V power supply voltage to 5V. The linear regulator is a linear regulator with a wide input voltage range, ensuring that the regulator circuit can still work normally when there is an 80V overvoltage surge. The input terminal of the linear regulator circuit is equipped with a diode to provide reverse connection protection.

[0046] Pin 5 of the linear regulator is connected to one end of resistor R201. Pins 3 and 4 of the linear regulator are connected to the other end of resistor R201 and the output terminal. Pin 5 of the linear regulator is also grounded through resistor R203. The output voltage of the linear regulator is adjusted by adjusting the voltage across resistors R201 and R203, specifically as follows:

[0047]

[0048] Among them, V ref It is the reference voltage, I ADJ This is the current at pin 5 of the linear regulator.

[0049] The linear regulator circuit is dual-channel. The dual-channel linear regulator circuit uses diodes to perform an "OR" operation to provide a stable power supply to the downstream timing generation circuit. The dual-channel linear regulator circuit includes linear regulator M210 and linear regulator M211. The output terminals of linear regulator M210 and linear regulator M211 are connected together using Schottky diode V201 and Schottky diode V202, respectively.

[0050] To prevent transient voltage spikes from the ground line, a diode V214 is used to isolate the ground line of the timing generation circuit from the output ground line of the linear regulator circuit.

[0051] The timing generation circuit produces a control waveform with a 90s high level and a 90s low level. Specifically, it includes an RC oscillation circuit and a frequency divider circuit. Upon power-up, because pin 9 of chip M201 is connected to a high level, the initial output of chip M201 is high. The RC oscillation circuit includes resistors R220 and R230, and capacitors C240 ​​and C241. The charging and discharging of either capacitor C240 ​​or C241 through resistors R220 and R230 generates a clock signal of a certain frequency. Resistors R220 and R230 are connected to pin 1 of chip M201, and capacitors C240 ​​or C241 are connected to pin 2 of chip M201. By calculating the RC value, pin 8 of chip M201 can output a control signal with a period of 90s high level and 90s low level. The rear end of pin 8 of chip M201 is connected to a follower circuit composed of operational amplifier M230.

[0052] The circuit period of the RC oscillator circuit is:

[0053]

[0054] Ground pins 12 and 13 of chip M201, set the frequency divider to 2^13, and the timing circuit output period is... Therefore, the period of the RC oscillator circuit is:

[0055]

[0056] Calculate the parameters of the RC oscillator circuit

[0057]

[0058] C240 and C241 are 100nF.

[0059]

[0060] Therefore, the resistance values ​​are: R220 is 191kΩ, and R230 is 66.5Ω.

[0061] The output control circuit uses an ideal diode driver chip M220 to convert the on-machine voltage into a heating power supply that is turned on for 90 seconds and turned off for 90 seconds. The ideal diode chip drives two back-to-back N-channel field-effect transistors Q201 and Q202 to achieve the on-off control of the output.

[0062] The two output control circuits serve as backups for each other, and their output terminals are connected to form an "OR" circuit.

[0063] Another embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0064] Figure 1 is a schematic diagram of the high-reliability propeller electric de-icing controller proposed in this invention. The input power supply range is 18V to 29V, and it can withstand a short-term surge voltage of 80V. Lightning protection circuits are designed at the input and output interfaces, enabling it to withstand a level 3 lightning induction test. A voltage spike circuit is designed at the input interface, enabling it to withstand a 600V 10µs voltage spike test. A dual-path linear voltage regulator circuit is designed, using diodes to achieve an "OR" operation to provide power to the downstream timing generation circuit. As long as one path of the linear voltage regulator circuit is functioning normally, the downstream timing generation circuit can operate normally, thereby improving reliability. A dual-path timing generation circuit is designed, and a phase synchronization circuit ensures that the output waveforms of the two timing generation circuits are in phase. The control waveforms output by the two timing generation circuits control the two output control circuits respectively, converting the DC power input from the aircraft into a heating power supply that is turned on for 90 seconds and turned off for 90 seconds. Because the phase and frequency of the control waveforms are the same, the frequency and phase of the heating power supply output by the two output control circuits are also exactly the same. Under normal circumstances, the two timing generation circuits and the two output control circuits work simultaneously and output in parallel, which can reduce conduction losses and improve overall efficiency. When either the timing generation circuit or the output control circuit has no output, the other one can work independently, thereby improving reliability and eliminating single-circuit faults in the electric de-icing controller.

[0065] This invention achieves lightning protection and voltage spike protection functions through a transient voltage suppression diode. The transient voltage suppression diode model is selected by calculating the lightning induced energy and the input voltage range. For a 600V 10µs voltage spike test, the energy is very small, and a 1500W transient voltage suppression diode is sufficient.

[0066] Figure 2 shows the schematic diagram of the linear voltage regulator circuit in the high-reliability propeller electric de-icing controller proposed in this invention. This circuit provides power to the timing generation circuit. Due to the very low power consumption required, linear voltage regulators M210 and M211 are selected to convert the 28V power supply voltage to 5V to provide voltage to the timing generation circuit, ensuring overall electromagnetic compatibility. Considering reverse connection protection and overvoltage surge protection, a linear voltage regulator with a wide input voltage range is selected to ensure that the voltage regulator circuit can still operate normally under an 80V overvoltage surge. Diodes V215 and V216 are connected in series at the circuit input for reverse connection protection. The diodes selected have a reverse withstand voltage of up to 150V to ensure that they will not be damaged in case of reverse connection. Because the linear voltage regulator circuit supplies power to the downstream timing generation circuit, and the chip used in the timing generation circuit has a relatively low withstand voltage, diode V214 is used to isolate the ground line of the timing generation circuit from the output ground line of the linear voltage regulator circuit to prevent transient voltage spikes from the input ground line, ensuring that transient voltage spikes from the input ground line will not affect the timing generation circuit. To prevent the timing circuit from being affected by the failure of a single circuit, the output filter capacitors C220 to C223 are connected in series to avoid short-circuiting the linear regulator circuit in case of capacitor failure. The linear regulator circuit employs a redundant design; the output terminals of the two linear regulator circuits are connected together using Schottky diodes V201 and V202 to form an OR circuit, improving the reliability of the linear regulator circuit. The output voltage of the linear regulator circuit can be adjusted by adjusting the voltage across resistors R201 to R204, as shown in the following formula:

[0067] (1)

[0068] Among them, V ref Reference voltage, I ADJ Refers to foot size 5.

[0069] The output voltage value of the other linear voltage regulator circuit is:

[0070]

[0071] Figure 3 shows the schematic diagram of the timing generation circuit in the high-reliability propeller electric de-icing controller proposed in this invention. This circuit is used to generate a control waveform with a 90s high level and a 90s ground level. The timing generation circuit consists of two parts: an RC oscillation circuit and a frequency divider circuit. When chip M201 is powered on, because pin 9 is connected to a high level, the initial output of chip M201 is high. The RC oscillation circuit generates a clock signal of a certain frequency by charging and discharging capacitors C240 / C241 through resistors R220 and R230. By calculating the RC value, pin 8 of chip M201 can output a control signal with a period of 90s high level and 90s low level. This achieves the function of 90s power-on and 90s power-off, with the power-on and power-off time determined by the RC value of the charging and discharging. To ensure the accuracy of the output signal, high-precision, low-temperature-drift resistors and capacitors are selected, with a temperature drift of ±30ppm / ℃ and an accuracy of ±5%. To ensure that a capacitor short-circuit fault will not cause a constant-on or no-output fault, two capacitors are connected in series.

[0072] To ensure the driving capability of the output model of the timing generator circuit, a follower circuit composed of operational amplifier M230 is designed at the back end to isolate the timing generator circuit from the back end output control circuit, ensuring that the timing generator circuit is not affected by the back end circuit, while improving the driving capability of the output model.

[0073] To improve reliability, the timing generation circuit adopts a redundant design, connecting pin 1 of the clock chips in the two timing generation circuits together through diode V203 and resistor R222 to ensure that the output phase and frequency of the two timing generation circuits are synchronized.

[0074] The RC oscillator circuit consists of R220, R230, C240, and C241, and the circuit period is:

[0075] (2)

[0076] Ground pins 12 and 13 of chip M201, set the frequency divider to 2^13, and the timing circuit output period is... Therefore, the period of the RC oscillator circuit is

[0077] (3)

[0078] Calculate the parameters of the RC oscillator circuit

[0079] (4)

[0080] C240 and C241 are 100nF.

[0081] (5)

[0082] Therefore, the resistance values ​​are: R220 is 191kΩ, and R230 is 66.5Ω.

[0083] Considering the allowable errors and temperature drift of resistors and capacitors, high-precision resistors and capacitors with low temperature drift are selected. The resistor accuracy is ±1% and the temperature drift is ±100ppm / ℃. The capacitor accuracy is ±5% over the entire temperature range and the temperature drift is ±30ppm / ℃.

[0084] Error impact calculation:

[0085] C240 and C241 are selected as 100nF capacitors, and they are connected in series. After calculating the actual error, the capacitance value is between 47.5nF and 52.5nF. The resistance values ​​are: R220 is 191kΩ, and R230 is 66.5Ω. After calculating the error... The current resistance should be between 190.87543 kΩ and 191.2575665 kΩ. Calculate the actual timing circuit period:

[0086] ………(6)

[0087] ……………(7)

[0088] Calculation of the effect of temperature drift:

[0089] C240 uses 100nF, with a temperature drift of ±30ppm / ℃ and an operating temperature range of -55℃ to 70℃. Calculations are based on a normal temperature of 25℃.

[0090] (8)

[0091] (9)

[0092] R220 has an RΩ rating of 191kΩ, R230 has an RΩ rating of 66.5kΩ, a temperature drift of ±100ppm / ℃, and an operating temperature range of -55℃ to 70℃. Calculations are based on a normal operating temperature of 25℃.

[0093] (10)

[0094] (11)

[0095] Selecting the maximum change value obtained from the above calculations, calculate the effect of temperature drift and the charging and discharging time of the multivibrator circuit:

[0096] (12)

[0097] (13)

[0098] Based on the above calculations, the impact of temperature drift of resistors and capacitors on the circuit is low, meeting the allowable error requirement of ±1%.

[0099] The capacitance tolerance has a significant impact on the circuit and cannot meet the ±1% tolerance requirement. However, this can be addressed by using a matching resistor. The resistance value meets the requirements. Due to the inherent error of the capacitor, the period of the timing generation circuit will have a large deviation. In the actual assembly process, the resistor needs to be adjusted according to the actual capacitance value used. The resistance value is adjusted to compensate for the output cycle of the timing generation circuit, achieving an allowable error of ±1%.

[0100] Figure 4 shows the schematic diagram of the output control circuit in the high-reliability propeller electric de-icing controller proposed in this invention. This circuit converts the on-board voltage into a heating power supply that is turned on for 90 seconds and off for 90 seconds. The output control circuit is implemented using an ideal diode driver chip M220, which drives two back-to-back N-channel MOSFETs Q201 and Q202 to achieve on / off control of the output. It also provides reverse connection protection and current backflow prevention. To eliminate single-point failures and improve reliability, two output control circuits are designed as backups for each other. The output terminals of the two output control circuits are connected together to form an OR circuit. Because the control waveforms output by the timing generator circuit have the same phase and frequency, the output phase and level of the two output control circuits are synchronized. When one output control circuit fails, it will only lead to an increase in overall power consumption, without causing functional loss. Considering the large current flowing through the N-channel MOSFETs, heat dissipation measures are added for the MOSFETs. Four N-channel MOSFETs are fixed to the bottom housing of the product with screws, and an insulating thermal pad is added between the N-channel MOSFETs and the product housing to reduce the thermal resistance between the two and improve the heat dissipation performance.

[0101] Figure 5 is a structural diagram of the high-reliability propeller electric de-icing controller proposed in this invention. The housing and the top cover are integrally formed. The protruding structure on the outer side of the top cover matches the groove structure of the housing. A conductive rubber strip is installed on the inner side of the top cover. The conductive rubber strip is pressed tightly by the mounting screws to ensure good sealing performance. At the same time, in order to avoid the accumulation of water vapor at the mounting screw position, the mounting screw position between the housing and the top cover is designed to be at the side end.

Claims

1. A high-reliability propeller electric de-icing controller, characterized in that, The system includes a lightning protection circuit, a voltage spike circuit, a linear regulator circuit, a timing generator circuit, and an output control circuit. Input and output interfaces are connected to other circuits via the lightning protection circuit. The input interface is also connected in series with the voltage spike circuit. The linear regulator circuit provides power to the downstream timing generator circuit. The control waveform output from the timing generator circuit controls the output control circuit, which converts the DC power input to the machine into a heating power supply with a 90-second on / 90-second off cycle. The timing generator circuit is dual-channel, with both channels synchronized by a phase synchronization circuit. The control waveforms output from the two timing generator circuits control the two output control circuits respectively. The linear regulator circuit includes a linear regulator that converts the 28V power supply voltage to 5V. The voltage regulator is a linear regulator with a wide input voltage range, ensuring normal operation even during an 80V overvoltage surge. A diode at the input of the linear regulator provides reverse connection protection. To prevent transient voltage spikes from the ground line, a diode V214 isolates the ground line of the timing generator circuit from the output ground line of the linear regulator circuit. The output control circuit uses an ideal diode driver chip M220 to convert the on-machine voltage into a heating power supply that is turned on for 90 seconds and off for 90 seconds. The ideal diode driver chip M220 drives two back-to-back N-channel MOSFETs Q201 and Q202 to control the output switching. The two output control circuits are backups of each other, and their outputs are connected to form an OR circuit.

2. The high-reliability propeller electric de-icing controller according to claim 1, characterized in that, Pin 5 of the linear regulator is connected to one end of resistor R201. Pins 3 and 4 of the linear regulator are connected to the other end of resistor R201 and the output terminal. Pin 5 of the linear regulator is also grounded through resistor R203. The output voltage of the linear regulator is adjusted by adjusting the voltage across resistors R201 and R203, specifically as follows: Among them, V ref It is the reference voltage, I ADJ This is the current at pin 5 of the linear regulator.

3. A high-reliability propeller electric de-icing controller according to claim 2, characterized in that, The linear regulator circuit is dual-channel. The dual-channel linear regulator circuit uses diodes to perform an "OR" operation to provide a stable power supply to the downstream timing generation circuit. The dual-channel linear regulator circuit includes linear regulator M210 and linear regulator M211. The output terminals of linear regulator M210 and linear regulator M211 are connected together using Schottky diode V201 and Schottky diode V202, respectively.

4. A high-reliability propeller electric de-icing controller according to claim 1, characterized in that, The timing generation circuit produces a control waveform with a 90s high level and a 90s low level. Specifically, it includes an RC oscillation circuit and a frequency divider circuit. Upon power-up, because pin 9 of chip M201 is connected to a high level, the initial output of chip M201 is high. The RC oscillation circuit includes resistors R220 and R230, and capacitors C240 ​​and C241. The charging and discharging of either capacitor C240 ​​or C241 through resistors R220 and R230 generates a clock signal of a certain frequency. Resistors R220 and R230 are connected to pin 1 of chip M201, and capacitors C240 ​​or C241 are connected to pin 2 of chip M201. By calculating the RC value, pin 8 of chip M201 can output a control signal with a period of 90s high level and 90s low level. The rear end of pin 8 of chip M201 is connected to operational amplifier M230 to form a follower circuit.

5. A high-reliability propeller electric de-icing controller according to claim 4, characterized in that, The circuit period of the RC oscillator circuit is: Ground pins 12 and 13 of chip M201, set the frequency divider to 2^13, and the timing circuit output period is... Therefore, the period of the RC oscillator circuit is: Calculate the parameters of the RC oscillator circuit C240 and C241 are 100nF. Therefore, the resistance values ​​are: R220 is 191kΩ, and R230 is 66.5Ω.

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