A multi-threshold rotational speed detection method and circuit

Abstract

The present application relates to the field of rotational speed signal detection, and more particularly to a multi-threshold rotational speed detection method and circuit. The multi-threshold rotational speed detection method includes: collecting an engine rotational speed signal; dividing the rotational speed signal into different frequency bands according to a low-frequency critical rotational speed and a high-frequency red-line rotational speed to obtain square wave signals of different thresholds through conditioning processing; obtaining frequency measurement values of the square wave signals of different thresholds; voting the frequency measurement values of different thresholds according to a voting algorithm, selecting an only frequency value according to a corresponding relationship between the frequency measurement values and the thresholds of each frequency band, converting the only frequency value into a rotational speed signal, and returning the rotational speed signal to an engine control loop to realize multi-threshold rotational speed detection of the engine. The multi-threshold rotational speed detection method not only widens the collection range of the rotational speed signal, but also improves the reliability and collection accuracy of the measured data.

Description

Technical Field

[0001] This invention relates to the field of rotational speed signal detection, and more specifically, to a multi-threshold rotational speed detection method and circuit. Background Technology

[0002] Rotational speed is a key performance indicator of aero-engines, and its signal acquisition and fault handling are crucial to the safe and efficient operation of aircraft and engines. Therefore, the measurement of aero-engine rotational speed signals requires extremely high accuracy and reliability.

[0003] When the aero-engine shaft rotates, the gap between the sound wheel mounted on it and the speed sensor changes periodically, causing the magnetic flux in the speed sensor to change periodically as well. This generates a periodically changing induced electromotive force, forming an electrical signal. The aero-engine controller processes, including conditioning, acquiring, and converting the electrical signal output from the speed sensor, to obtain the engine speed. This speed is then applied to the control algorithm to implement control principles, while the speed information is transmitted to the aircraft.

[0004] However, the operating environment of the speed sensor is harsh, with numerous sources of interference, making the output signal susceptible to superimposed interference and noise, resulting in a complex actual output signal. When the engine speed increases linearly from zero, the speed sensor output signal also increases from zero. However, due to factors such as installation location, coil winding, and the internal environment of the engine, its output voltage signal exhibits an approximately linear relationship with the engine speed, and shows different corresponding relationships in low, medium, and high speed scenarios.

[0005] Traditional speed sensor signal acquisition uses a hysteresis comparator circuit with a single threshold voltage. However, because the actual output signal of the speed sensor is complex, if the threshold voltage is designed too high, it will lead to the failure to detect small signals; if the threshold voltage is designed too low, it will reduce the anti-interference capability, causing interference in the complex engine system to enter the control system as glitches through the acquisition circuit, affecting the speed acquisition accuracy, and in severe cases, even causing problems in the engine control loop.

[0006] Therefore, there is an urgent need for a wide-range speed measurement method applicable to complex engine environments. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-threshold speed detection method and circuit, which solves the technical problem in the prior art that the hysteresis comparison circuit with a single threshold voltage cannot acquire low-frequency signals and is easily interfered with in complex signal environments, resulting in poor engine speed acquisition accuracy.

[0008] To achieve the above objectives, the present invention provides a multi-threshold rotational speed detection method comprising:

[0009] Acquire engine speed signal;

[0010] Based on the low-frequency critical speed and the high-frequency redline speed, the speed signals in different frequency bands are conditioned and processed to obtain square wave signals with different thresholds.

[0011] Obtain frequency measurements of square wave signals with different thresholds;

[0012] The frequency measurement values ​​of different thresholds are voted on according to the voting algorithm. A unique frequency value is selected and output according to the correspondence between the frequency measurement value and the threshold of each frequency band. The unique frequency value is converted into a speed signal and returned to the engine control loop to realize the multi-threshold speed detection of the engine.

[0013] In one embodiment, the step of conditioning the rotation speed signal by dividing it into different frequency bands further includes:

[0014] The rotational speed signal is conditioned by using hysteresis comparison circuits with different thresholds, corresponding to low-frequency, mid-frequency, and high-frequency thresholds.

[0015] Among them, the threshold for the high-frequency band is greater than that for the mid-frequency band, and the threshold for the mid-frequency band is greater than that for the low-frequency band.

[0016] In one embodiment, the hysteresis comparator circuit sets different threshold voltages based on rotational speed signals of different frequency bands, wherein:

[0017] The amplitude range of the low-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the first low threshold voltage value V. OL 1. Second highest threshold voltage value V OH 1;

[0018] The amplitude range of the mid-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the second low threshold voltage value V. OL 2. Second highest threshold voltage value V OH 2;

[0019] The amplitude range of the high-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the third lowest threshold voltage value V. OL 3. The third highest threshold voltage value V OH 3;

[0020] And satisfy V OL 1 <V OL 2 <V OL 3, V OH 1 <V OH 2 <V OH 3.

[0021] In one embodiment, the frequency measurements of the different threshold square wave signals are obtained in the following manner:

[0022] The frequency of the square wave signal is measured using the period measurement method, and the output frequency of the square wave signal at different thresholds is dynamically detected by using a dual threshold judgment of count value and reference value.

[0023] In one embodiment, the step of determining the threshold using both the count value and the reference value further includes:

[0024] Determine whether a rising edge of the speed signal is detected. Based on whether a rising edge is detected, output the period of the speed signal to obtain the frequency measurement value.

[0025] In one embodiment, if no rising edge of the rotational speed signal is detected, the following actions are further performed:

[0026] Determine if the count value is greater than the overflow threshold; if it is, perform overflow handling.

[0027] The overflow handling operation includes identifying the overflow value, setting the counter to the maximum value, resetting the reference value, and saving the current measurement data.

[0028] If the count is less than the overflow threshold, the count will continue to accumulate.

[0029] In one embodiment, if a rising edge of the rotational speed signal is detected, the following actions are further performed:

[0030] Determine whether the conditions for the count value to reach the maximum value or the reference value to reach the preset value are met;

[0031] If the condition is met, save the current count value, perform a counter clearing operation, and reset the reference value;

[0032] If the condition is not met, continue counting the number of rising edges and update the count value and reference value.

[0033] In one embodiment, the step of selecting a unique output frequency value based on the correspondence between the frequency measurement value and the threshold values ​​of each frequency band includes:

[0034] When all frequency measurements are greater than the high-frequency threshold, select the high-frequency threshold for speed signal conditioning;

[0035] When the frequency measurement value is between the high-frequency threshold and the mid-frequency threshold, select the mid-frequency threshold for speed signal conditioning;

[0036] When the frequency measurement value is between the mid-frequency threshold and the low-frequency threshold, select the low-frequency threshold for speed signal conditioning;

[0037] When the frequency measurement value is lower than the low-frequency threshold, the maximum value of the output frequency value in the dynamic threshold conditioning circuit is selected.

[0038] To achieve the above objectives, the present invention proposes a multi-threshold speed detection circuit, which includes a speed sensor, a dynamic threshold conditioning circuit, a frequency measurement unit, and a voting circuit to execute the multi-threshold speed detection method described above:

[0039] The speed sensor is used to collect engine speed signals;

[0040] The dynamic threshold conditioning circuit is used to convert analog signals into square wave signals to realize multi-threshold speed detection of the engine;

[0041] The frequency measurement unit is used to measure the frequency of the square wave signal respectively;

[0042] The voting circuit is used to output a unique frequency value according to a preset voting algorithm.

[0043] In one embodiment, the dynamic threshold conditioning circuit includes a low threshold conditioning circuit, a medium threshold conditioning circuit, and a high threshold conditioning circuit:

[0044] The low threshold conditioning circuit is used to condition the speed signal of the low-frequency band threshold.

[0045] The mid-threshold conditioning circuit is used to condition the rotational speed signal at the mid-frequency threshold.

[0046] The high threshold conditioning circuit is used to condition the speed signal of the high-frequency threshold.

[0047] In one embodiment, the multi-threshold speed detection circuit further includes a filter circuit, a limiting circuit, and an amplification circuit connected in sequence.

[0048] The filtering circuit employs a filter to remove interference and noise from the speed signal;

[0049] The limiting circuit consists of two diodes connected in reverse parallel to limit the signal amplitude and protect the subsequent circuitry.

[0050] The amplifier circuit uses an amplifier to adjust the signal ratio.

[0051] The present invention provides a multi-threshold speed detection method and circuit, which optimizes the circuit structure, acquisition logic and algorithm based on the traditional speed acquisition system. It can accurately identify speed signals, significantly improve the performance and reliability of speed signal acquisition, broaden the acquisition range of speed signals, and enhance anti-interference ability, thereby improving the reliability and acquisition accuracy of the measured data. Attached Figure Description

[0052] The above-described and other features, properties, and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals consistently denote the same features.

[0053] in:

[0054] Figure 1 A flowchart of a multi-threshold rotational speed detection method according to one aspect of the present invention is disclosed;

[0055] Figure 2 A circuit diagram for a multi-threshold rotational speed detection according to one aspect of the present invention is disclosed;

[0056] Figure 3 The variation of output voltage and input voltage of the hysteresis comparator circuit according to one aspect of the present invention is disclosed.

[0057] Relationship diagram;

[0058] Figure 4 A frequency measurement logic flowchart of a frequency measurement unit according to one aspect of the present invention is disclosed;

[0059] Figure 5 A voting flowchart of a voting circuit according to one aspect of the present invention is disclosed.

[0060] The meanings of the labels in the figures are as follows:

[0061] 10 speed sensors;

[0062] 20. Filter circuit;

[0063] 21. First filter sub-circuit;

[0064] 22. Second filter circuit;

[0065] 23. Third filter circuit;

[0066] 30-degree limiting circuit;

[0067] 31 First limiting sub-circuit;

[0068] 32. Second limiting sub-circuit;

[0069] 33. Third limiting sub-circuit;

[0070] 40 Amplifier Circuit;

[0071] 41 First amplifier sub-circuit;

[0072] 42. Second amplifier sub-circuit;

[0073] 43. Third amplifier sub-circuit;

[0074] 50 Dynamic Threshold Conditioning Circuit;

[0075] 51 Low threshold conditioning circuit;

[0076] 52 threshold conditioning circuits;

[0077] 53 High threshold conditioning circuit;

[0078] 60 frequency measurement units;

[0079] 61 First frequency measurement subunit;

[0080] 62 Second frequency measurement subunit;

[0081] 63 Third frequency measurement subunit;

[0082] 70 Voting Circuit. Detailed Implementation

[0083] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0084] This invention proposes a multi-threshold speed detection method, which solves the technical problem that the traditional speed sensor signal acquisition uses a hysteresis comparison circuit with a single threshold voltage, resulting in poor engine speed acquisition accuracy.

[0085] Figure 1 A flowchart of a multi-threshold rotational speed detection method according to one aspect of the present invention is disclosed, such as... Figure 1 As shown, the present invention proposes a multi-threshold rotational speed detection method, which includes:

[0086] S1. Acquire engine speed signal;

[0087] S2. Based on the low-frequency critical speed and the high-frequency redline speed, the speed signals in different frequency bands are conditioned and processed to obtain square wave signals with different thresholds.

[0088] S3. Obtain the frequency measurement values ​​of square wave signals with different thresholds;

[0089] S4. Voting is performed on the frequency measurement values ​​of different thresholds according to the voting algorithm. A unique frequency value is selected and output according to the correspondence between the frequency measurement value and the threshold of each frequency band. The unique frequency value is converted into a speed signal and returned to the engine control loop to realize the multi-threshold speed detection of the engine.

[0090] This invention proposes a wide-range, multi-threshold speed detection method. It matches different speed signals using high, medium, and low frequency thresholds, and combines this with a voting algorithm to derive the final speed, which is then fed into the engine control loop. Compared to traditional systems, this method obtains the square wave signal frequency through a dynamic threshold conditioning circuit, uses a period measurement method to obtain three frequency values, and then processes them through a voting algorithm to obtain the accurate speed, thereby improving measurement accuracy and anti-interference capability.

[0091] To achieve the above method, this invention proposes a multi-threshold rotational speed detection circuit.

[0092] Figure 2 A circuit diagram for a multi-threshold rotational speed detection according to one aspect of the present invention is disclosed, such as... Figure 2 As shown, the circuit may include a speed sensor 10, a filter circuit 20, a limiting circuit 30, an amplification circuit 40, a dynamic threshold conditioning circuit 50, a frequency measurement unit 60, and a voting circuit 70.

[0093] The speed sensor 10 is used to collect engine speed signals. Generally speaking, the speed sensor 10 can be a magnetoelectric sensor used to sense the speed on an aircraft engine. The engine speed refers to the rotational speed of the high-pressure rotor and the low-pressure rotor of the engine.

[0094] The filter circuit 20 may include a first filter sub-circuit 21, a second filter sub-circuit 22, and a third filter sub-circuit 23. The filter can be used to filter out interference and noise in the speed signal output by the speed sensor 10. Generally, the filter can be implemented by an RC low-pass filter to improve measurement accuracy.

[0095] The limiting circuit 30 may include a first limiting sub-circuit 31, a second limiting sub-circuit 32, and a third limiting sub-circuit 33, which are used to limit abnormal high voltage signals generated externally, protect subsequent circuits, and stabilize the voltage of the signal after filtering. It can be implemented by two diodes connected in reverse parallel.

[0096] The amplifier circuit 40 may include a first amplification sub-circuit 41, a second amplification sub-circuit 42, and a third amplification sub-circuit 43, used to amplify the signal after passing through the limiting circuit 30. It is mainly implemented by an operational amplifier to amplify the filtered and limited signal to a suitable amplitude for subsequent processing.

[0097] It can enhance the signal, improve the signal-to-noise ratio, and ensure that the signal can be accurately processed in subsequent circuits.

[0098] The filter circuit 20, the limiting circuit 30, and the amplification circuit 40 are connected in sequence to the dynamic threshold conditioning circuit 50. The dynamic threshold conditioning circuit 50 may include a low threshold conditioning circuit 51, a medium threshold conditioning circuit 52, and a high threshold conditioning circuit 53. The dynamic threshold conditioning circuit 50 receives the rotation speed signal and outputs a square wave signal.

[0099] The low threshold conditioning circuit 51 is used to condition the speed signal of the low frequency band (low speed). It is implemented by the hysteresis comparator circuit, focusing on signal conditioning when the engine is at low speed, and converting the amplified signal into a square wave signal.

[0100] The mid-threshold conditioning circuit 52 is used to condition the speed signal of the mid-frequency band (mid-speed). It is implemented by a hysteresis comparator circuit, which focuses on processing the speed sensor signal when the engine is running normally and converts the amplified signal into a square wave signal.

[0101] The high threshold conditioning circuit 53 is used to condition the speed signal of the high-frequency (high speed) threshold. It is implemented by the hysteresis comparator circuit, focusing on signal conditioning when the engine is at high speed, and converting the amplified signal into a square wave signal.

[0102] The dynamic threshold conditioning circuit adjusts the signal threshold according to different speed ranges, converts the amplified signal into a square wave signal, and performs waveform conversion on the amplified signal. This circuit is mainly implemented by a voltage comparator, which not only ensures the detection capability of low-frequency signals but also the anti-interference capability of mid- and high-frequency signals, ensuring the accuracy and stability of signal processing at different speeds.

[0103] The frequency measurement unit 60 measures the frequency of the square wave signal after it has passed through the dynamic threshold conditioning circuit. This is accomplished by the frequency measurement logic circuit. Specifically, it measures the frequency of the processed signal and converts the electrical signal into an actual rotational speed value.

[0104] The voting circuit 70 selects the final output frequency according to a preset voting algorithm, and votes on the frequencies acquired by the dynamic threshold conditioning circuit and the frequency measurement logic. The voted signal is sent to the engine control loop, mainly implemented by the logic circuit. Specifically, it comprehensively judges the frequency measurement values ​​output by the frequency measurement unit, selects the most reliable speed value, improves the reliability and accuracy of the measurement results, and avoids errors from a single measurement point.

[0105] The multi-threshold speed detection circuit proposed in this invention can effectively identify speed signals, broaden the acquisition range of speed signals, improve the anti-interference ability of speed signal acquisition, enhance the reliability of measured data, and ensure the acquisition accuracy of speed signals.

[0106] It should be noted that the filter circuit, limiting circuit, amplification circuit, and frequency measurement unit can adopt similar designs for the low, medium, and high speed signal channels.

[0107] In one embodiment, the speed sensor 10 acquires a speed signal, which is then filtered by a first filtering sub-circuit 21 to remove noise and interference, limited by a first amplitude limiting sub-circuit 31, amplified by a first amplification sub-circuit 41, and further processed by a low threshold conditioning circuit 51. Finally, it enters a first frequency measurement sub-unit 61 to measure the frequency.

[0108] The speed sensor 10 acquires the speed signal. The signal passes through the second filter sub-circuit 22 to remove noise and interference, then through the second amplitude limiting sub-circuit 32 to limit the signal amplitude, then through the second amplification sub-circuit 42 to amplify the signal, and then enters the middle threshold conditioning circuit 52 for further processing. Finally, it enters the second frequency measurement sub-unit 62 to measure the frequency.

[0109] The speed sensor 10 acquires the speed signal. The signal passes through the third filter sub-circuit 23 to remove noise and interference, then through the third amplitude limiting sub-circuit 33 to limit the signal amplitude, then through the third amplification sub-circuit 43 to amplify the signal, and then enters the high threshold conditioning circuit 53 for further processing. Finally, it enters the third frequency measurement sub-unit 63 to measure the frequency.

[0110] The output results of the three frequency measurement subunits are sent to the voting circuit 70 for voting to obtain the final speed measurement result, ensuring the accuracy and reliability of speed measurement.

[0111] This invention proposes a multi-threshold speed detection circuit. The speed signal is detected by a speed sensor and then sequentially filtered, limited, and amplified. Based on the current speed range, a corresponding speed threshold adjustment circuit is selected for processing. Different speed ranges require different thresholds to accurately identify the signal, which allows the frequency measurement unit to calculate the speed value more precisely. Finally, a voting circuit comprehensively judges the speed values ​​output by multiple frequency measurement units and outputs the final speed value, improving the reliability and accuracy of the final output speed value.

[0112] The steps of the multi-threshold rotational speed detection method proposed in this invention will be described in detail below. It should be understood that, within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined and related to each other to form preferred technical solutions.

[0113] The following will combine Figure 1 and Figure 2 ,based on Figure 2 The multi-threshold rotational speed detection circuit shown above provides a detailed description of the above steps of the multi-threshold rotational speed detection method proposed in this invention.

[0114] S1. Acquire engine speed signal. Optionally, the speed sensor 10 acquires the engine speed signal.

[0115] S2. Based on the low-frequency critical speed and the high-frequency redline speed, the speed signals of different frequency bands are divided and conditioned to obtain square wave signals with different thresholds.

[0116] It is worth noting that in the field of aero-engines, low-frequency critical speed and high-frequency redline speed play a crucial role in engine design, operation and maintenance.

[0117] Low-frequency critical speed refers to the engine speed signal with a low frequency, which usually corresponds to the engine running at high speed; high-frequency redline speed refers to the engine speed signal with a high frequency, which usually corresponds to the engine running at high speed. Exceeding this speed may cause equipment damage or unstable operation.

[0118] In one embodiment, conditioning the rotation speed signal by dividing it into different frequency bands further includes:

[0119] The rotational speed signal is conditioned by using hysteresis comparison circuits with different thresholds, corresponding to low-frequency, mid-frequency, and high-frequency thresholds.

[0120] Among them, the threshold for the high-frequency band is greater than that for the mid-frequency band, and the threshold for the mid-frequency band is greater than that for the low-frequency band.

[0121] In other words, the low-threshold conditioning circuit, the medium-threshold conditioning circuit, and the high-threshold conditioning circuit correspond to the speed signal conditioning of the low-frequency, medium-frequency, and high-frequency thresholds, respectively.

[0122] In one embodiment, frequency band allocation can be as follows:

[0123] Low-frequency threshold: The first-order speed at which the engine speed signal frequency is lower than the low-frequency critical speed;

[0124] High-frequency threshold: The second-order speed at which the engine speed signal frequency is higher than the high-frequency redline speed;

[0125] Mid-frequency threshold: The third-order speed between the low-frequency critical speed and the high-frequency redline speed of the engine speed signal frequency.

[0126] It should be noted that in practical applications, the division of frequency bands needs to be defined in conjunction with the working principle, physical characteristics, and actual requirements of the aero-engine. Different engines have different frequency band divisions, and those skilled in the art need to determine the low-frequency critical speed and high-frequency redline speed of different engines through dynamic analysis and experimental testing. The low-frequency, mid-frequency, and high-frequency bands can be discontinuous or continuous.

[0127] The dynamic threshold conditioning circuit is implemented by hysteresis comparator circuits with different thresholds. Each hysteresis comparator circuit operates on the same principle. The hysteresis comparator circuit is used to enhance the stability of the circuit to input voltage changes and uses positive feedback to suppress frequent changes in the input and output states caused by small fluctuations in the input voltage.

[0128] Figure 3 A graph showing the relationship between the output voltage and input voltage of a hysteresis comparator circuit according to one aspect of the present invention is disclosed, such as... Figure 3 As shown, the relationship between the output voltage (V0) and the input voltage (V1) in the hysteresis comparator circuit is as follows:

[0129] V OL It is the threshold voltage at which the hysteresis comparator circuit transitions from a high level (Vcc) to a low level (0V).

[0130] V OH It is the threshold voltage for the hysteresis comparator circuit to switch from a low level (0V) to a high level (Vcc).

[0131] Vcc is the high-level output voltage of the circuit.

[0132] The low-level output voltage of the circuit is 0V.

[0133] Hysteresis comparator circuits use two different threshold voltages (V) OL and V OH This effectively improves the circuit's stability in response to changes in the input signal. When the input voltage (V1) rises and reaches V... OH When the input voltage drops and reaches V0, the output voltage (V0) will jump from a low level to a high level. Conversely, when the input voltage drops and reaches V0, the output voltage will jump from a low level to a high level. OL When this happens, the output voltage will jump from a high level to a low level.

[0134] Hysteresis comparator circuits utilize positive feedback mechanisms, preventing the circuit from frequently switching between high and low levels when there are slight fluctuations in the input voltage, thereby enhancing the circuit's anti-interference capability.

[0135] In one embodiment, the hysteresis comparator circuit sets different threshold voltages based on rotational speed signals at different frequency bands, wherein:

[0136] The amplitude range of the low-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the first low threshold voltage value V. OL 1. Second highest threshold voltage value V OH 1;

[0137] The amplitude range of the mid-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the second low threshold voltage value V. OL 2. Second highest threshold voltage value V OH 2;

[0138] The amplitude range of the high-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the third lowest threshold voltage value V. OL 3. The third highest threshold voltage value V OH 3;

[0139] And satisfy V OL 1 <V OL 2 <V OL 3, V OH 1 <V OH 2 <V OH 3.

[0140] In this embodiment, the threshold voltage of the hysteresis comparator circuit in the low-frequency threshold conditioning circuit is set to be low to adapt to the characteristics of low-speed signals. Since the amplitude of low-speed signals is usually small, a lower threshold is required to ensure that these signals can be accurately detected. The low threshold setting helps to improve the detection sensitivity of low-frequency signals and avoid signal missed detection.

[0141] The mid-frequency threshold conditioning circuit is suitable for speed monitoring during normal engine operation. It can provide stable signal conditioning and detection within the medium speed range, ensuring normal engine control and operation.

[0142] The threshold voltage of the hysteresis comparator circuit in the high-frequency threshold conditioning circuit is set to a high value. This is used for signal detection when the engine is under high load or high speed. The higher threshold can effectively suppress high-frequency noise and interference, improve the anti-interference capability of the system, effectively process high-frequency signals, and prevent control errors caused by signal interference.

[0143] After processing by the dynamic threshold conditioning circuit, the speed signal is converted into a square wave signal. The frequency of the speed signal is measured by the frequency measurement unit. The measured frequency is then passed through the voting circuit to calculate the physical value of the speed.

[0144] Figure 4 A frequency measurement logic flowchart of a frequency measurement unit according to one aspect of the present invention is disclosed, such as... Figure 4 As shown, the frequency measurements of square wave signals with different thresholds were obtained in the following ways:

[0145] The frequency of the square wave signal is measured using the period measurement method, and the output frequency of the square wave signal at different thresholds is dynamically detected by using a dual threshold judgment of count value and reference value.

[0146] In one embodiment, the frequency measurement unit 60 uses the period measurement method to measure the frequency of the square wave signal. By using a dual threshold judgment of the count value and the reference value, the output frequency of the square wave signal at different thresholds is detected and the frequency measurement value is output, thereby improving the reliability of the measured data.

[0147] The step of determining thresholds using both count values ​​and reference values ​​further includes:

[0148] Determine whether a rising edge of the speed signal is detected. Based on whether a rising edge is detected, output the period of the speed signal to obtain the frequency measurement value.

[0149] In one embodiment, if no rising edge of the rotational speed signal is detected, the following actions are further performed:

[0150] Determine if the count value is greater than the overflow threshold; if it is, perform overflow handling.

[0151] The overflow handling operation includes identifying the overflow value, setting the counter to the maximum value, resetting the reference value, and saving the current measurement data.

[0152] If the count is less than the overflow threshold, the count will continue to accumulate.

[0153] In this embodiment, if no rising edge of the speed signal is detected, it is determined whether the count value C is greater than the overflow threshold. When the count value C reaches the overflow value, the overflow flag can be set to 1, and the count value C is set to the maximum value C. max The reference value R can be set to 1 and the data saved; if the count value does not reach the overflow value, the count value C = C + 1 is executed.

[0154] In one embodiment, if a rising edge of the rotational speed signal is detected, the following actions are further performed:

[0155] Determine whether the conditions for the count value to reach the maximum value or the reference value to reach the preset value are met;

[0156] If the condition is met, save the current count value, perform a counter clearing operation, and reset the reference value;

[0157] If the condition is not met, continue counting the number of rising edges and update the count value and reference value.

[0158] In this embodiment, if a rising edge of the rotational speed signal is detected, the count value C reaches its maximum value or the reference value R reaches a preset value R. set If the count value is not reached, the counter will be cleared and the reference value R = 1 will be reset. If the count value is not reached and the reference value is not reached, the count of rising edges will continue to be counted.

[0159] This invention uses a period measurement method to measure the frequency output of a dynamic threshold conditioning circuit. Specifically, it combines a reference value and a count value, synchronously controls the measurement period, and calculates the frequency of the signal. This method balances the accuracy and real-time performance of high and low frequency signals, and reduces the limitations caused by the fixed window in traditional frequency measurement methods (such as high-frequency omissions or long waiting times for low frequencies). It is suitable for dynamically changing signals (engine speed signals) or wide-range frequency measurements.

[0160] Figure 5 A voting flowchart of a voting circuit according to one aspect of the present invention is disclosed. Figure 5 As shown, the voting circuit votes on the comparison results between the frequency output by the dynamic threshold conditioning circuit 50 (low threshold conditioning circuit 51, medium threshold conditioning circuit 52, and high threshold conditioning circuit 53) and the threshold frequency based on the frequency measurement unit 60. Further, based on the voting algorithm, a unique output frequency value (final rotational speed) for the final rotational speed is selected according to the correspondence between the frequency measurement value and the threshold values ​​of each frequency band, including the following cases:

[0161] The step of selecting a unique output frequency value based on the correspondence between the frequency measurement value and the threshold values ​​of each frequency band includes:

[0162] When all frequency measurements are greater than the high-frequency threshold, select the high-frequency threshold for speed signal conditioning;

[0163] When the frequency measurement value is between the high-frequency threshold and the mid-frequency threshold, select the mid-frequency threshold for speed signal conditioning;

[0164] When the frequency measurement value is between the mid-frequency threshold and the low-frequency threshold, select the low-frequency threshold for speed signal conditioning;

[0165] When the frequency measurement value is lower than the low-frequency threshold, the maximum value of the output frequency value in the dynamic threshold conditioning circuit is selected.

[0166] In one embodiment, when the measured frequency values ​​output by the dynamic threshold conditioning circuit are all greater than the high-frequency threshold, the signal amplitude output by the speed sensor is relatively high, and the amplitude of the corresponding interference is also relatively large. Therefore, the frequency value output by the high threshold conditioning circuit is selected.

[0167] In one embodiment, when the measured frequency value output by the dynamic threshold conditioning circuit is between the high-frequency threshold and the mid-frequency threshold, the frequency value output by the mid-frequency threshold conditioning circuit is selected.

[0168] In one embodiment, when the measured frequency value output by the dynamic threshold conditioning circuit is between the mid-frequency threshold and the low-frequency threshold, the frequency value output by the low-threshold conditioning circuit is selected.

[0169] In one embodiment, when the measured frequency value output by the dynamic threshold conditioning circuit is lower than the low-frequency threshold, the signal amplitude output by the speed sensor is relatively low, and the frequency value output by the dynamic threshold conditioning circuit is relatively low. The high threshold conditioning circuit may miss detection, and the low threshold conditioning circuit may introduce interference. Therefore, the maximum value of the output frequency value in the dynamic threshold conditioning circuit is selected during the voting process, which can both avoid signal miss detection and increase reliability.

[0170] This invention employs a voting algorithm based on dynamic threshold rotational speed frequency, which dynamically adjusts the threshold according to signal strength, thereby improving detection accuracy. It balances sensitivity and anti-interference capability under different conditions, avoids missed detections, reduces noise interference, and ensures the acquisition accuracy of rotational speed signals. The voting mechanism enhances the reliability and robustness of the entire multi-threshold rotational speed detection circuit.

[0171] The present invention provides a multi-threshold speed detection method and circuit, which optimizes the circuit structure, acquisition logic and algorithm based on the traditional speed acquisition system. It can accurately identify speed signals, significantly improve the performance and reliability of speed signal acquisition, broaden the acquisition range of speed signals, and enhance anti-interference ability, thereby improving the reliability and acquisition accuracy of the measured data.

[0172] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0173] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0174] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps are described above in a generalized manner in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as departing from the scope of the invention.

[0175] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor such that the processor can read and write information to / from the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside as discrete components in the user terminal.

[0176] The above embodiments are provided for those skilled in the art to implement or use the present invention. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited to the above embodiments, but should be the maximum scope that conforms to the innovative features mentioned in the claims.

Claims

1. A multi-threshold rotational speed detection method, characterized in that, The method includes: Acquire engine speed signal; Based on the low-frequency critical speed and the high-frequency redline speed, the speed signals in different frequency bands are conditioned and processed to obtain square wave signals with different thresholds. Obtain frequency measurements of square wave signals with different thresholds; The frequency measurement values ​​of different thresholds are voted on according to the voting algorithm. A unique frequency value is selected and output according to the correspondence between the frequency measurement value and the threshold of each frequency band. The unique frequency value is converted into a speed signal and returned to the engine control loop to realize the multi-threshold speed detection of the engine.

2. The multi-threshold rotational speed detection method according to claim 1, characterized in that, The step of conditioning the speed signal by dividing it into different frequency bands further includes: The rotational speed signal is conditioned by using hysteresis comparison circuits with different thresholds, corresponding to low-frequency, mid-frequency, and high-frequency thresholds. Among them, the threshold for the high-frequency band is greater than that for the mid-frequency band, and the threshold for the mid-frequency band is greater than that for the low-frequency band.

3. The multi-threshold rotational speed detection method according to claim 2, characterized in that, The hysteresis comparator circuit sets different threshold voltages based on the rotational speed signals of different frequency bands, wherein: The amplitude range of the low-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the first low threshold voltage value V. OL 1. Second highest threshold voltage value V OH 1; The amplitude range of the mid-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the second low threshold voltage value V. OL 2. Second highest threshold voltage value V OH 2; The amplitude range of the high-frequency speed signal corresponds to the threshold voltage values ​​of the hysteresis comparator circuit, including: the third lowest threshold voltage value V. OL 3. The third highest threshold voltage value V OH 3; And satisfy V OL 1 <V OL 2 <V OL 3, V OH 1 <V OH 2 <V OH 3.

4. The multi-threshold rotational speed detection method according to claim 1, characterized in that, The frequency measurements of the square wave signals with different thresholds are obtained through the following method: The frequency of the square wave signal is measured using the period measurement method, and the output frequency of the square wave signal at different thresholds is dynamically detected by using a dual threshold judgment of count value and reference value.

5. The multi-threshold rotational speed detection method according to claim 4, characterized in that, The step of determining the threshold using both the count value and the reference value further includes: Determine whether a rising edge of the speed signal is detected. Based on whether a rising edge is detected, output the period of the speed signal to obtain the frequency measurement value.

6. The multi-threshold rotational speed detection method according to claim 5, characterized in that, If no rising edge of the speed signal is detected, the following actions are performed: Determine if the count value is greater than the overflow threshold; if it is, perform overflow handling. The overflow handling operation includes identifying the overflow value, setting the counter to the maximum value, resetting the reference value, and saving the current measurement data. If the count is less than the overflow threshold, the count will continue to accumulate.

7. The multi-threshold rotational speed detection method according to claim 5, characterized in that, If a rising edge of the speed signal is detected, the following actions are further performed: Determine whether the conditions for the count value to reach the maximum value or the reference value to reach the preset value are met; If the condition is met, save the current count value, perform a counter clearing operation, and reset the reference value; If the condition is not met, continue counting the number of rising edges and update the count value and reference value.

8. The multi-threshold rotational speed detection method according to claim 4, characterized in that, The step of selecting a unique output frequency value based on the correspondence between the frequency measurement value and the threshold values ​​of each frequency band includes: When all frequency measurements are greater than the high-frequency threshold, select the high-frequency threshold for speed signal conditioning; When the frequency measurement value is between the high-frequency threshold and the mid-frequency threshold, select the mid-frequency threshold for speed signal conditioning; When the frequency measurement value is between the mid-frequency threshold and the low-frequency threshold, select the low-frequency threshold for speed signal conditioning; When the frequency measurement value is lower than the low-frequency threshold, the maximum value of the output frequency value in the dynamic threshold conditioning circuit is selected.

9. A multi-threshold rotational speed detection circuit, characterized in that, The multi-threshold speed detection circuit includes a speed sensor, a dynamic threshold conditioning circuit, a frequency measurement unit, and a voting circuit to perform the multi-threshold speed detection method as described in any one of claims 1-8: The speed sensor is used to collect engine speed signals; The dynamic threshold conditioning circuit is used to convert analog signals into square wave signals to realize multi-threshold speed detection of the engine; The frequency measurement unit is used to measure the frequency of the square wave signal respectively; The voting circuit is used to select the final output unique frequency value according to a preset voting algorithm.

10. The multi-threshold rotational speed detection circuit according to claim 9, characterized in that, The dynamic threshold conditioning circuit includes a low threshold conditioning circuit, a medium threshold conditioning circuit, and a high threshold conditioning circuit: The low threshold conditioning circuit is used to condition the speed signal of the low-frequency band threshold. The mid-threshold conditioning circuit is used to condition the rotational speed signal at the mid-frequency threshold. The high threshold conditioning circuit is used to condition the speed signal of the high-frequency threshold.

11. The multi-threshold rotational speed detection circuit according to claim 10, characterized in that, The multi-threshold speed detection circuit further includes a filter circuit, a limiting circuit, and an amplification circuit connected in sequence. The filtering circuit employs a filter to remove interference and noise from the speed signal; The limiting circuit consists of two diodes connected in reverse parallel to limit the signal amplitude and protect the subsequent circuitry. The amplifier circuit uses an amplifier to adjust the signal ratio.

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