Low-delay variable rotation frequency measurement

Abstract

A system and method for measuring the rotational frequency in a rotating machine uses a variable sliding measurement window. The system and method calculate and store the number of internal clock cycles between the start of a measurement interval and each pulse signal from a pulse generator. The rotational frequency is determined by the difference between the count of the most recent pulse signal and the count of a previous pulse signal within the measurement interval. The number of pulse signals occurring between the most recent and previous pulse signals represents the measurement window. This measurement window, or its size, can then be used, along with the count difference, to determine the rotational frequency. The measurement window can then be slid to the next most recent pulse signal and the next previous pulse signal to obtain a new count difference, etc.

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to U.S. Provisional Application No. 62 / 956,123, filed December 31, 2019, entitled “Low Latency Variable Rotational Frequency Measurements,” and is re-incorporated hereby. Technical Field

[0003] This disclosure relates to systems and methods for measuring the rotational frequency in electric motors, turbines and similar rotating machines, and more particularly to systems and methods for providing variable frequency measurements and parallel variable frequency measurements to improve measurement response time with high accuracy and low latency when measuring the rotational frequency of such rotating machines. Background Technology

[0004] Rotating machines (such as motors, turbines, etc.) require rapid and accurate measurement of their rotational frequency for proper control and operation, and to prevent speeding conditions that could damage the machine and / or endanger personnel. The term "rotational frequency" as used herein refers to the number of times a gear or similar object rotates about an axis within a given unit of time, and is typically measured in revolutions per minute (rpm). In a typical arrangement, a sensor is mounted close to the gear of the rotating machine. As the machine operates and the gear rotates, the sensor generates a pulse signal for each gear tooth, which passes through a point on or near the sensor. Various types of sensors can be used for this purpose, including mechanical sensors, magnetic sensors, optical sensors, etc. Each pulse signal triggers a counter that captures the amount of time elapsed since the previous pulse signal (typically by counting the number of internal clock cycles since the previous pulse signal). The controller uses the time elapsed between pulse signals (the number of clock cycles) to determine the rotational frequency of the gear.

[0005] However, although much progress has been made in the technology for measuring rotational frequency, it is easy to understand that continuous improvement is still needed. Summary of the Invention

[0006] Embodiments of this disclosure provide a system and method for measuring the rotational frequency in a rotating machine using a variable sliding measurement window. The system and method store the elapsed time since the start of a measurement interval and each pulse signal from a pulse generator. This elapsed time is captured and stored as a count of the number of internal clock cycles elapsed since the start of the measurement interval and each pulse signal. For a given measurement interval, each count is stored separately and sequentially, such that a new measurement interval resets the count and begins a new sequence of stored counts. The rotational frequency is determined by the difference between the count of the most recent pulse signal and the count of a predefined previous pulse signal within the measurement interval. The number of pulse signals that have occurred between the most recent and previous pulse signals represents the measurement window. This measurement window (or more precisely, its size) can then be used, along with the count difference, to determine the rotational frequency within the measurement interval. The measurement window can then slide to the count of the next most recent pulse signal and the next previous pulse signal to obtain a new count difference, and so on. In this way, changes in the rotational frequency can be captured rapidly on a continuous basis, because any change will manifest as an increase or decrease in the count difference as the measurement window slides to the count of the next pulse signal. The aforementioned arrangement also allows for very low latency because the new / updated rotational frequency measurement is determined using existing, previously captured counts.

[0007] In some embodiments, the size of the sliding window can dynamically change within a given measurement interval as the measurement differs, or dynamically change with different measurement intervals, depending on the needs of a particular application.

[0008] In some embodiments, multiple sliding windows can be used in parallel to simultaneously obtain multiple count differences and rotational frequency measurements. In some cases, the sliding windows may partially overlap, or in others, they may remain separate. A mathematical function (such as an averaging function) can then be applied to the rotational frequency measurements to produce a composite rotational frequency measurement.

[0009] In some embodiments, a frequency divider can be used to divide the pulse signal from the pulse generator. The frequency divider can produce a divided signal, wherein, depending on the size of the frequency divider, a single pulse of the divided signal reflects or corresponds to several pulses of the original pulse signal within a given measurement interval. This arrangement reduces implementation complexity by avoiding the need to sample each individual pulse of the original pulse signal within the measurement interval.

[0010] In general, in one aspect, embodiments of this disclosure relate to a rotational frequency measurement circuit. The rotational frequency measurement circuit particularly includes a counter configured to count clock cycles of a clock signal during a measurement interval. The counter is operable to output a count value upon receiving a pulse corresponding to at least one of several protrusions on a rotating component of a rotating machine. The count value represents the number of clock cycles that have elapsed since the start of the measurement interval. The rotational frequency measurement circuit also includes a memory coupled to the counter and configured to receive multiple count values ​​from the counter during the measurement interval. The memory is operable to store each count value separately and sequentially during the measurement interval. The rotational frequency measurement circuit also includes a frequency processor coupled to the memory. The frequency processor is operable to determine the rotational frequency of the rotating component using the difference between the most recent count value and a selected previous count value, and a measurement window representing the number of pulses that have occurred between the most recent and previous count values ​​during the measurement interval.

[0011] In general, in another aspect, embodiments of this disclosure relate to a method for measuring rotational frequency. The method specifically includes receiving pulses at a counter during a measurement interval, the counter being configured to count clock cycles of a clock signal during the measurement interval, the pulses corresponding to at least one of several protrusions on a rotating component of a rotating machine. The method also includes outputting a count value at the counter upon receiving a pulse, the count value representing the number of clock cycles that have elapsed since the start of the measurement interval, and receiving multiple count values ​​from the counter during the measurement interval at a memory coupled to the counter. The method further includes storing each count value received separately and sequentially from the counter during the measurement interval at the memory, and determining the rotational frequency of the rotating component at a frequency processor coupled to the memory using the difference between the most recent count value and a selected previous count value, and a measurement window representing the number of pulses that have occurred between the most recent count value and the previous count value during the measurement interval.

[0012] According to any one or more of the foregoing embodiments, the counter is configured to reset at the start of a new measurement interval, and the memory is a circular buffer configured to start a new sequence of stored counter values ​​at the start of a new measurement interval.

[0013] According to any one or more of the foregoing embodiments, the frequency processor may also be operable to slide the measurement window to the next most recent count value and the next previous count value in the memory, and use the difference between the next most recent count value and the next previous count value and the measurement window to determine the rotation frequency of the rotating component, and / or the frequency processor may also be operable to change the size of the measurement window during the measurement interval in response to a change in the rotation speed of the rotating component.

[0014] According to any one or more of the foregoing embodiments, the rotation frequency is a first rotation frequency, and the frequency processor is also operable to determine a second rotation frequency of the rotating component while determining the first rotation frequency. The frequency processor uses a second difference between a second most recent count value and a second previous count value and a second measurement window to determine the second rotation frequency, and optionally, the frequency processor is also operable to use the first rotation frequency and the second rotation frequency to generate a composite rotation frequency.

[0015] According to any one or more of the foregoing embodiments, the frequency processor is also operable to calculate the optimal size of the measurement window using one or more of the minimum rotational frequency of the rotating component, the maximum rotational frequency, the measurement interval, and the error percentage. According to any one or more of the foregoing embodiments, the variable frequency divider is configured to provide pulses to the counter, the pulses provided by the variable frequency divider corresponding to several protrusions on the rotating component, and optionally, the frequency processor is also operable to calculate the optimal division value of the variable frequency divider using one or more of the minimum rotational frequency of the rotating component, the maximum rotational frequency, the measurement interval, and the error percentage. Attached Figure Description

[0016] A more detailed description of the present disclosure, which has been briefly summarized above, can be obtained by referring to various embodiments, some of which are illustrated in the accompanying drawings. While the drawings illustrate selected embodiments of the present disclosure, they should not be considered as limiting its scope, as the present disclosure may allow for other equally effective embodiments.

[0017] Figure 1 This is a schematic diagram illustrating an exemplary system for measuring the rotational frequency of a rotating machine according to an embodiment of the present disclosure;

[0018] Figure 2 This is a timing diagram illustrating an exemplary method for measuring rotational frequency according to an embodiment of the present disclosure;

[0019] Figures 3A-3D This is a functional diagram illustrating an exemplary rotational frequency measurement according to an embodiment of the present disclosure;

[0020] Figure 4 This is a functional diagram illustrating an exemplary method for measuring rotational frequency according to embodiments of the present disclosure; and

[0021] Figure 5 This is a functional diagram illustrating an alternative method for measuring rotational frequency according to an embodiment of the present disclosure.

[0022] Where possible, the same reference numerals are used to denote the same elements in the drawings. However, elements disclosed in one embodiment may be advantageously used in other embodiments without specific description. Detailed Implementation

[0023] Now for reference Figure 1 This illustration shows a schematic diagram of an exemplary system 100 for measuring the rotational frequency in a rotating machine 102 according to an embodiment of the present disclosure. In this example, the rotating machine 102 can be any type of machine that uses rotating components (such as gear 104 having a known number of protrusions such as gear teeth 106) and rotates about a shaft 108 or other axis during operation of the rotating machine 102. Such a rotating machine 102 can include various turbines (e.g., steam turbines, gas turbines, hydro turbines, and wind turbines), internal combustion engines, electric motors, generators, compressors, and other machines that use or have rotating components. A pulse generator 110 is mounted adjacent to the gear 104 for detecting the gear teeth 106. The pulse generator 110 can be a mechanical, magnetic, optical, or any suitable rotation sensor capable of generating a pulse signal corresponding to each gear tooth 106. A rotational frequency measurement circuit 112 receives and processes the pulse signals from the pulse generator 110 to determine the rotational frequency of the gear 104. This rotational frequency, typically provided in revolutions per minute (rpm), can then be used by various systems (such as control system 114 and / or overspeed protection system 116) to control the operation of the rotating machine 102.

[0024] exist Figure 1 In the example, the rotation frequency measurement circuit 112 processes the pulse signal and uses several components to determine the rotation frequency. These components are shown herein as functional blocks and include a clock 118, a counter 120, a memory 122, and a frequency processor 124, among other components. Typically, the clock 118 provides an internal clock signal that serves as an internal time base, while the counter 120 operates to count the clock cycles of the clock signal. The memory 122 stores the counts from the counter 120, and the frequency processor 124 uses the stored counts to determine the rotation frequency of the gear 104. Preferably, the rotation frequency measurement circuit 112 (or one or more components thereof) is implemented using programmable logic, such as a microprocessor, a programmable logic controller (PLC), a field-programmable gate array (FPGA), etc.

[0025] Figure 2This is a timing diagram illustrating the operation of some of the components described above according to an embodiment of the present disclosure. In this example, the clock is an internal clock signal provided by clock 118, the pulse is a pulse input signal provided by pulse generator 110, and the measurement interval is a pre-selected time interval 128 during which clock cycles are counted to determine the rotation frequency. Memory 122 is analogous to a circular buffer or queue having a series of data registers 126 that are sequentially filled and can be looped back to the first data register when the filling process needs to restart. Each data register is labeled n. q For reference, "q" represents the register index number (i.e., q=0 is the first data register, q=1 is the second data register, and so on).

[0026] In operation, the rising edge of the first pulse input signal within the measurement interval 128 starts / resets the counter 120 to begin counting clock cycles of the internal clock signal. This first rising edge (and each subsequent rising edge) also causes the counter 120 to output the current raw counter value 130 to the memory 122, which captures this counter value 130 in the first data register n0, denoted as Count0. The rising edge of the second pulse input signal causes the counter 120 to output the next counter value 132 to the memory 122, which captures the next counter value 132 in the next data register n1, denoted as Count1, and so on. This process continues until the end of the measurement interval 128 is reached, after which the counter 120 is reset, and the memory 122 wraps back to the first data register n0 to store the new current counter value 134 in the new measurement interval 128. Therefore, for a given measurement interval 128 of length, the memory 122 needs to have a sufficient number of data registers 124 to hold each captured counter value in a separate data register.

[0027] Figures 3A-3D This is a functional diagram illustrating the operation of a rotational frequency measurement circuit 112 and, in particular, a frequency processor 124 according to embodiments of the present disclosure. In these examples, gear 104 is assumed to have 60 teeth, which results in pulse generator 110 generating 60 pulses per revolution.

[0028] First refer to Figure 3A In some embodiments, the frequency processor 124 determines the rotational frequency by acquiring a count difference D between the most recent counter value (e.g., Count3, i.e., q = 4) and some selected previous counts (e.g., Count1, i.e., q = 2)). The frequency processor 124 then uses this count difference D in the following equation to determine the rotational frequency of the gear 104:

[0029]

[0030] In equation (1) above, 60 is the time conversion factor (i.e., 60 seconds / minute), T is the duration of the clock signal, G is the number of pulses per revolution generated by the gear teeth, and p is a measurement window reflecting the difference in the number of pulse input signals between the two counter values ​​(i.e., Count3 and Count1) constituting D. In this example, the value of the measurement window p is 2 pulses (i.e., 3 – 1 = 2), and the value of G is 60 pulses / revolution. If from Figure 2 We can assume each clock cycle is 100 μs, and there are 10 clock cycles in each pulse input signal. Then the duration T of the clock signal is 0.0001 seconds / cycle, and the value of D is 20 cycles (i.e., 30 – 10 = 20). The result is that the RPM (rotational frequency measurement) is approximately 1000 rpm (i.e., (2 pulses × 60 seconds / minute) / (20 cycles × 0.0001 seconds / cycle × 60 pulses / revolution)).

[0031] Figure 3B The diagram illustrates the rotational frequency measurement circuit 112 sliding its measurement window p to the next data register. This allows the rotational frequency measurement circuit 112 to obtain a new count difference D between the new most recent counter value (now Count4) and the new previous count (now Count2), and so on. In this way, the rotational frequency measurement circuit 112 can rapidly capture changes in the rotational frequency of the gear 104 on a continuous basis, because any change will manifest as an increase or decrease in the value of the count difference D as the measurement window p slides to the next data register. The aforementioned arrangement also allows the rotational frequency measurement circuit 112 to withstand very low latency because it uses the already existing, previously captured counter value to determine the new / updated rotational frequency measurement. Low latency is particularly important for certain applications requiring extremely fast measurement response times, such as overspeed detection systems (ODS) and similar applications.

[0032] In addition, such as Figure 3CAs shown, the rotational frequency measurement circuit 112 can dynamically change the size of the sliding measurement window p on an as-needed basis, depending on the specific application and the measurement. For example, as the rotational frequency of gear 104 changes, the sliding window p (e.g., 2 pulses) can increase or decrease to p' (e.g., 1 pulse, 3 pulses, etc.). This variable sliding window can better maintain accuracy when the rate of change of rpm changes (e.g., when gear 104 is accelerating and rpm is detected to be accelerating). In this case, the sliding window can be dynamically reduced to reduce response time. Conversely, when gear 104 is decelerating and rpm is detected to be decelerating, the sliding window can be dynamically increased to improve accuracy. In some embodiments, the sliding window p can be a multiple of G (e.g., 2G, 3G, 4G, etc.), where it is desirable for the sliding window to extend beyond the number of revolutions of one gear (e.g., p = 60, 120, 180, 240, etc.).

[0033] In addition, such as Figure 3D As shown, the rotational frequency measurement circuit 112 can use multiple sliding measurement windows to perform multiple rotational frequency measurements in parallel. For example, the rotational frequency measurement circuit 112 can use a first measurement window p1 to obtain a first count difference D1 and a rotational frequency measurement value RPM1, while using a second measurement window p2 to obtain a second count difference D2 and a rotational frequency measurement value RPM2. In some embodiments, the two sliding measurement windows can partially overlap each other, or in some embodiments, they can remain separate. These parallel measurements can be performed using a sufficiently large cyclic buffer (e.g., an FPGA) as memory 122 to accommodate additional counts, especially if the sliding windows do not overlap. The rotational frequency measurement circuit 112 can then apply a mathematical function (such as an averaging function) to the two rotational frequency measurements RPM1 and RPM2 to produce a composite rotational frequency measurement value (i.e., RPM = (RPM1 + RPM2) / 2). Alternatively, the rotational frequency measurement circuit 112 can simply select the last of the two measurements in time as the rotational frequency measurement value.

[0034] In the foregoing embodiments, a window size algorithm or model can be developed to dynamically predict the optimal sliding window size p for a given measurement. This model may be in the form of an equation in some embodiments and can be developed using statistical and numerical techniques known to those skilled in the art, including by applying machine learning to rotational frequency measurement data collected over time. Such a model can be configured, at least in part, based on the desired minimum and maximum rotational frequencies of a given rotating machine application, the desired measurement intervals for the application, and / or the maximum percentage of error for the application, as well as other configuration parameters. This model can then be incorporated into the rotational frequency measurement circuitry and used to dynamically calculate the optimal sliding window size that should be used for a given rotational frequency measurement. This allows the rotational frequency measurement circuitry to consistently adjust the sliding window size to achieve high accuracy within the desired rotational frequency range, even within the same measurement intervals. In this way, when the rotational frequency of the application changes, the rotational frequency measurement circuitry can begin to recover high accuracy as quickly as the next rotational frequency measurement.

[0035] Figure 4 This is a functional diagram illustrating an exemplary method 400, which can be used with a rotational frequency measurement circuit to measure the rotational frequency using a dynamically calculated, model-based sliding measurement window. Method 400 typically begins at block 402, where a minimum frequency, maximum frequency, measurement interval, and maximum error percentage are selected for the rotational frequency measurement circuit, if not previously done. At block 404, an appropriate clock frequency is selected for the rotational frequency measurement circuit based on the input from block 402, if not previously done, and the size of the sliding window is set to an initial value, for example, p = 1. At block 406, the number of gear teeth (i.e., pulses per revolution) is selected, if not previously done.

[0036] In box 408, the clock signal frequency is set using the clock frequency selection from box 404, and in box 410, the next window size (i.e., the number of pulse input (PI) signals) is set for the rotation frequency measurement circuit. Initially, this window size can be the initial window size selected in box 404, but can subsequently be calculated using an algorithm or model similar to that described above. In box 412, the pulse input signal is provided. In box 414, any signal conditioning that may be required is provided. Subsequently, the rotation frequency measurement circuit determines the rotation frequency as described above in box 416 (see equation (1)) and outputs the rotation frequency in box 418. The rotation frequency is also provided as feedback to box 410 so that the rotation frequency measurement circuit can dynamically calculate the next window size using the algorithm or model therein.

[0037] Figure 5This is a functional diagram illustrating an exemplary method 500, which can be used with a rotational frequency measurement circuit to measure the rotational frequency by dividing the frequency of a pulsed input signal using a frequency divider. As shown in 501, the frequency divider generates a divided signal, wherein a single pulse of the divided signal reflects or corresponds to several pulses of the original pulsed input signal within a given measurement interval, depending on the size of the frequency divider. This arrangement reduces implementation complexity by avoiding the need to sample each individual pulse of the original pulsed input signal within the measurement interval.

[0038] Method 500 typically begins with block 502, where, as previously described, the minimum frequency, maximum frequency, measurement interval, and maximum error percentage are selected for the rotational frequency measurement circuit, if not previously done. In block 504, an appropriate clock frequency is selected for the rotational frequency measurement circuit based on the input from block 502, if not previously done, and the divider size is set to an initial value, for example, divider value = 1. In block 506, the number of gear teeth (i.e., pulses per revolution) is selected, if not previously done.

[0039] In block 508, the clock signal frequency is set using the clock frequency selection from block 504, and in block 510, the next divider value is set. Initially, this divider value can be the initial divider value selected in block 504, but it can subsequently be calculated using an algorithm or model similar to that described above. In block 512, a pulse input signal is provided. In block 514, any signal conditioning that may be required is provided. Subsequently, in block 516, the conditioned pulse input signal is divided using the divider value of 1 from block 510. Subsequently, the rotation frequency measurement circuit in block 516 uses the divided signal to determine the rotation frequency (e.g., using equation (1) modified to take into account the divided signal). The rotation frequency measurement circuit then outputs the rotation frequency in block 518 and also provides the rotation frequency as feedback to block 510. In block 510, the rotation frequency measurement circuit dynamically calculates the next divider value using the algorithm or model therein.

[0040] The above examples demonstrate numerous advantages over existing speed measurement systems and methods. Additional examples and advantages can be found in the attached appendix. Figure 1-5 It can be seen from the attached Figure 1-5 Includes additional implementation details and Figures 4-5The mathematical model of the embodiment includes configuration parameters and analysis of measurement intervals and errors. These advantages include a dynamically configurable parametric measurement model driven by frequency range, accuracy, and measurement intervals. Additional advantages include a sliding variable-size window design with on-demand, low-latency measurements. Further advantages include a method for consistently achieving high-precision rotational speed measurement within the same measurement interval across the entire frequency range. Further advantages include a method for restoring full measurement accuracy in the next measurement interval when the rotational frequency changes. In this way, measurement errors can be controlled and minimized even under abnormal, extreme conditions. These additional advantages include rapid parallel measurements at lower frequencies and stable results, which is particularly useful for AC frequency and phase difference measurements, power factor correction in power generation, or for any other application requiring accurate and rapid rotational speed measurement.

[0041] Various embodiments have been referenced above. However, the scope of this disclosure is not limited to the embodiments specifically described. Rather, any combination of the described features and elements, whether or not associated with different embodiments, is contemplated for implementing and practicing the contemplated embodiments. Furthermore, while embodiments may achieve advantages over other possible solutions or prior art, whether a particular advantage is achieved by a given embodiment does not limit the scope of this disclosure. Therefore, the foregoing aspects, features, embodiments, and advantages are merely illustrative and should not be considered as elements or limitations of the appended claims unless expressly stated in the claims.

[0042] The various embodiments disclosed herein can be implemented as systems, methods, or computer program products. Therefore, aspects can take the form of entirely hardware embodiments, entirely software embodiments (including firmware, resident software, microcode, etc.), or embodiments combining software and hardware aspects, which are generally referred to herein as “circuit,” “module,” or “system.” Furthermore, aspects can take the form of computer program products embodied in one or more computer-readable media having computer-readable program code embodied thereon.

[0043] Any combination of one or more computer-readable media may be used. The computer-readable medium may be a non-transitory computer-readable medium. A non-transitory computer-readable medium may be, for example, but not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or any suitable combination thereof. More specific examples (not an exhaustive list) of non-transitory computer-readable media may include: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. Program code embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, fiber optic cable, RF, etc., or any suitable combination thereof.

[0044] Computer program code used to perform the operations of various aspects of this disclosure can be written in any combination of one or more programming languages. Furthermore, such computer program code can be executed using a single computer system or multiple computer systems communicating with each other (e.g., using a local area network (LAN), wide area network (WAN), the Internet, etc.). Although the various features described above are with reference to flowchart illustrations and / or block diagrams, those skilled in the art will understand that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks of the flowchart illustrations and / or block diagrams, can be implemented by computer logic (e.g., computer program instructions, hardware logic, combinations of both, etc.). Typically, computer program instructions can be provided to processor(s) of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus. Furthermore, executing such computer program instructions using processor(s) produces a machine capable of performing the functions(s) or actions(s) specified in one or more blocks of the flowchart illustrations and / or block diagrams.

[0045] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and / or operation of various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, code segment, or code portion, which includes one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative embodiments, the functions mentioned in the blocks may occur in a non-consecutive order. For example, two blocks shown consecutively may actually be executed substantially simultaneously, or these blocks may sometimes be executed in reverse order, depending on the functions involved. It will also be noted that each block illustrated in the block diagrams and / or flowcharts, and combinations of blocks illustrated in the block diagrams and / or flowcharts, may be implemented by a system based on dedicated hardware or a combination of dedicated hardware and computer instructions that performs the specified function or action.

[0046] It should be understood that the above description is intended to be illustrative and not restrictive. Many other embodiments will become apparent from reading and understanding the above description. While specific examples have been described herein, it should be recognized that the systems and methods of this disclosure are not limited to the examples described herein but can be implemented with modifications within the scope of the appended claims. Therefore, the specification and drawings are to be considered illustrative and not restrictive. Consequently, the scope of this disclosure should be determined by reference to the appended claims and the full scope of their equivalents.

Claims

1. A rotational frequency measuring circuit, comprising: A counter is configured to count the clock cycles of a clock signal during a measurement interval. The counter is operable to output a count value upon receiving a pulse, the pulse corresponding to at least one of several protrusions on a rotating part of a rotating machine. The count value represents the number of clock cycles that have elapsed since the start of the measurement interval. A memory, coupled to the counter and configured to receive multiple count values ​​from the counter during the measurement interval, the memory being operable to store each count value separately and sequentially during the measurement interval; and A frequency processor, coupled to the memory, is operable to determine the rotational frequency of the rotating component using the difference between a recent count value and a selected previous count value, and a measurement window representing the number of pulses that have occurred between the recent count value and the previous count value during the measurement interval. The frequency processor is also operable to slide the measurement window to the next recent count value and the next previous count value in the memory, and use the difference between the next recent count value and the next previous count value, and the measurement window, to determine the rotational frequency of the rotating component. The counter is configured to reset at the start of a new measurement interval.

2. The circuit according to claim 1, wherein, The rotation frequency is a first rotation frequency, and the frequency processor is also operable to determine a second rotation frequency of the rotating component while determining the first rotation frequency, the frequency processor using a second difference between a second most recent count value and a second previous count value and a second measurement window to determine the second rotation frequency.

3. The circuit according to claim 2, wherein, The frequency processor is also operable to use the first rotation frequency and the second rotation frequency to generate a composite rotation frequency.

4. The circuit of claim 1 further includes a variable frequency divider configured to provide the pulse to the counter, wherein the pulse provided by the variable frequency divider corresponds to several protrusions on the rotating component.

5. The circuit according to claim 4, wherein, The frequency processor is also operable to calculate the optimal division value of the variable frequency divider using one or more of the minimum rotation frequency, maximum rotation frequency, measurement interval, and error percentage of the rotating component.

6. The circuit according to claim 1, wherein, The memory is a cyclic buffer configured to begin a new sequence of stored counter values ​​at the start of a new measurement interval.

7. The circuit according to claim 1, wherein, The frequency processor is also operable to change the size of the measurement window during the measurement interval in response to changes in the rotational speed of the rotating component.

8. The circuit according to claim 1, wherein, The frequency processor is also operable to calculate the optimal size of the measurement window using one or more of the minimum rotation frequency, maximum rotation frequency, measurement interval, and error percentage of the rotating component.

9. A method for measuring rotational frequency, comprising: At a counter, pulses are received during the measurement interval, the counter being configured to count the clock cycles of a clock signal during the measurement interval, the pulses corresponding to at least one of several protrusions on a rotating part of a rotating machine; At the counter, a count value is output when the pulse is received, the count value representing the number of clock cycles that have elapsed since the start of the measurement interval; At a memory coupled to the counter, multiple count values ​​are received from the counter during the measurement interval; The memory stores each count value received separately and sequentially from the counter during the measurement interval; At the frequency processor coupled to the memory, the rotation frequency of the rotating component is determined using the difference between the most recent count value and a selected previous count value, as well as a measurement window representing the number of pulses that have occurred between the most recent count value and the previous count value during the measurement interval. At the frequency processor, the measurement window is slid to the next most recent count value and the next previous count value in the memory, and the frequency processor uses the difference between the next most recent count value and the next previous count value and the measurement window to determine the rotation frequency of the rotating component; as well as The counter is reset at the start of a new measurement interval.

10. The method according to claim 9, wherein, The rotation frequency is a first rotation frequency, and the method further includes determining a second rotation frequency of the rotating component at the frequency processor while determining the first rotation frequency, the frequency processor using a second difference between a second most recent count value and a second previous count value and a second measurement window to determine the second rotation frequency.

11. The method of claim 10, further comprising using the first rotation frequency and the second rotation frequency at the frequency processor to generate a synthesized rotation frequency.

12. The method of claim 9, further comprising providing the pulse to the counter at a variable frequency divider, the pulse provided by the variable frequency divider corresponding to several protrusions on the rotating component.

13. The method of claim 12, further comprising using one or more of the minimum rotational frequency, maximum rotational frequency, measurement interval, and error percentage of the rotating component at the frequency processor to calculate the optimal division value of the variable frequency divider.

14. The method according to claim 9, wherein, The memory is a cyclic buffer, and the method further includes storing a new sequence of counter values ​​in the cyclic buffer at the start of a new measurement interval.

15. The method of claim 9, further comprising, at the frequency processor, changing the size of the measurement window during the measurement interval in response to a change in the rotational speed of the rotating component.

16. The method of claim 9, further comprising using one or more of the minimum rotational frequency, maximum rotational frequency, measurement interval, and error percentage of the rotating component at the frequency processor to calculate the optimal size of the measurement window.

17. A rotational frequency measuring circuit, comprising: A counter is configured to count the clock cycles of a clock signal during a measurement interval. The counter is operable to output a count value upon receiving a pulse, the pulse corresponding to at least one of several protrusions on a rotating part of a rotating machine. The count value represents the number of clock cycles that have elapsed since the start of the measurement interval. A memory, coupled to the counter and configured to receive multiple count values ​​from the counter during the measurement interval, the memory being operable to store each count value separately and sequentially during the measurement interval; and A frequency processor, coupled to the memory, is operable to determine the rotational frequency of the rotating component using the difference between a recent count value and a selected previous count value, and a measurement window representing the number of pulses that have occurred between the recent count value and the previous count value during the measurement interval. The frequency processor is also operable to slide the measurement window to the next recent count value and the next previous count value in the memory, and use the difference between the next recent count value and the next previous count value, and the measurement window, to determine the rotational frequency of the rotating component. The memory is a cyclic buffer configured to start a new sequence of stored counter values ​​at the beginning of a new measurement interval.

18. A method for measuring rotational frequency, comprising: At a counter, pulses are received during the measurement interval, the counter being configured to count the clock cycles of a clock signal during the measurement interval, the pulses corresponding to at least one of several protrusions on a rotating part of a rotating machine; At the counter, a count value is output when the pulse is received, the count value representing the number of clock cycles that have elapsed since the start of the measurement interval; At a memory coupled to the counter, multiple count values ​​are received from the counter during the measurement interval; The memory stores each count value received separately and sequentially from the counter during the measurement interval; At the frequency processor coupled to the memory, the rotation frequency of the rotating component is determined using the difference between the most recent count value and a selected previous count value, as well as a measurement window representing the number of pulses that have occurred between the most recent count value and the previous count value during the measurement interval. as well as At the frequency processor, the measurement window is slid to the next most recent count value and the next previous count value in the memory, and the frequency processor uses the difference between the next most recent count value and the next previous count value and the measurement window to determine the rotation frequency of the rotating component; The memory is a cyclic buffer, and also includes a new sequence of counter values ​​stored in the cyclic buffer at the start of a new measurement interval.

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