Low latency variable rotation frequency measurement

Abstract

To provide a system and a method for providing variable frequency measurement and parallel variable frequency measurement in order to improve measurement response time with high accuracy and low latency when measuring a rotation frequency of a rotary machine.SOLUTION: The number of internal clock cycles between a start of a measurement interval and each pulse signal from a pulse generator 110 is counted and stored. Rotational frequency is determined by taking difference between a count for a most recent pulse signal and a count for some previous pulse signal within the measurement interval. The number of pulse signals that have occurred between the most-recent pulse signal and the previous pulse signal represents a window of measurement. This window of measurement, or size thereof, can then be used along with count difference to determine the rotational frequency. The window of measurement can then be slid to the counts for a next most recent pulse signal and counts of a next previous pulse signal to obtain new count difference.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This patent application claims the benefit of priority to U.S. Provisional Application No. 62 / 956,123, entitled "Low Latency Variable Rotational Frequency Measurement," filed December 31, 2019, which is incorporated herein by reference.

[0002] The present disclosure relates to systems and methods for measuring rotational frequency in 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 machines. [Background technology]

[0003] Rotating machines, such as motors, turbines, and the like, require fast and accurate measurement of their rotational frequency for proper control and operation and to prevent overspeed conditions that could damage the machine and / or endanger personnel. As used herein, the term "rotational frequency" refers to the number of times a gear or similar object rotates around its axis over a given unit of time, typically measured in revolutions per minute (rpm). In a typical arrangement, a sensor is mounted in close proximity to a gear of the rotating machine. As the machine operates and the gear rotates, the sensor generates a pulse signal for each gear tooth that passes a point on or near the sensor. Various types of sensors can be used for this purpose, including mechanical, magnetic, and optical sensors. Each pulse signal typically triggers a counter that captures the elapsed time since the previous pulse signal by counting the number of internal clock cycles since the previous pulse signal. A controller uses the elapsed time (number of clock cycles) between pulse signals to determine the gear's rotational frequency.

[0004] However, it will be readily appreciated that although many advances have been made in the technology for measuring rotational frequency, there is a continuing need for improvement. Summary of the Invention

[0005] An embodiment of the present disclosure provides a system and method for measuring the rotational frequency of a rotating machine using a variable sliding window of measurement. The system and method stores the elapsed time from the start of the measurement interval and each pulse signal from a pulse generator. The elapsed time is captured and stored as a count of the number of internal clock cycles that have elapsed since the start of the measurement interval and each pulse signal. Each count is stored individually and sequentially for a given measurement interval, such that a new measurement interval resets the count and begins a new sequence of stored counts. The rotational frequency is determined by taking the difference between the count for the most recent pulse signal and the count for any predefined immediately preceding pulse signal within the measurement interval. The number of pulse signals occurring between the most recent pulse signal and the immediately preceding pulse signal represents the measurement window. This measurement window, or its size, along with the count difference, is used 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 immediately preceding pulse signal to obtain a new count difference. In this way, changes in the rotational frequency can be continuously and quickly captured, as the change appears as an increase or decrease in the count difference as the measurement window slides to the count of the next pulse signal. The above arrangement also allows for very low latency, as new / updated rotation frequency measurements are determined using the already existing, most recently captured count.

[0006] In some embodiments, the size of the sliding window can be dynamically changed from measurement to measurement within a given measurement interval, or from measurement interval to measurement interval, as needed for a particular application.

[0007] In some embodiments, multiple sliding windows may be used in parallel to simultaneously obtain multiple count difference measurements and rotational frequency measurements. The sliding windows may overlap or remain separate. A mathematical function, such as an averaging function, may then be applied to the rotational frequency measurements to generate a resulting rotational frequency measurement.

[0008] In some embodiments, the pulse signal from the pulse generator can be divided using a divider such that, depending on the size of the divider, a single pulse of the divided signal reflects or generates a corresponding divided signal that reflects several pulses of the original pulse signal over a given measurement interval. Such an arrangement reduces implementation complexity by avoiding the need to sample each individual pulse of the original pulse signal over the measurement interval.

[0009] In general, in one aspect, embodiments of the present disclosure relate to a rotational frequency measurement circuit. The rotational frequency measurement circuit includes, among other things, a counter configured to count clock cycles of a clock signal during a measurement interval, the counter operable to output a count value upon receiving a pulse, the pulse corresponding to at least one of a plurality of protrusions on a rotating component of a rotating machine, the count value representing the number of clock cycles that have elapsed since the beginning of the measurement interval. The rotational frequency measurement circuit also includes a memory coupled to the counter and configured to receive a plurality of count values ​​from the counter during the measurement interval, the memory operable to individually sequentially store each count value during the measurement interval. The rotational frequency measurement circuit further includes a frequency processor coupled to the memory, the frequency processor operable to determine the rotational frequency of the rotating component using a difference between a most recent count value and a selected immediately preceding count value and a measurement window representing the number of pulses occurring between the most recent count value and the immediately preceding count value during the measurement interval.

[0010] In general, in another aspect, embodiments of the present disclosure relate to a method for measuring a rotational frequency, the method including, among other things, receiving pulses during a measurement interval at a counter, the counter configured to count clock cycles of a clock signal during the measurement interval, the pulses corresponding to at least one of a plurality of protrusions on a rotating component of a rotating machine. The method also includes outputting a count value representing a number of clock cycles elapsed since a start of the measurement interval upon receipt of the pulse at the counter, and receiving, at a memory coupled to the counter, a plurality of count values ​​from the counter during the measurement interval. The method further includes individually sequentially storing each count value received from the counter during the measurement interval in the memory, and determining, at a frequency processor coupled to the memory, a rotational frequency of the rotating component using a difference between a most recent count value and a selected immediately preceding count value and a measurement window, the measurement window representing the number of pulses occurring between the most recent count value and the immediately preceding count value during the measurement interval.

[0011] According to any one or more of the above-described embodiments, the counter is configured to reset at the start of a new measurement interval, and the memory is a circular buffer configured to begin a new sequence of stored counter values ​​at the start of a new measurement interval.

[0012] In accordance with any one or more of the above described embodiments, the frequency processor may be further operable to slide a measurement window to the next most recent count value and the next immediately preceding count value in the memory and use the difference between the next most recent count value and the next immediately preceding count value and the measurement window to determine the rotational frequency of the rotating component, and the frequency processor may be further operable to vary the size of the measurement window during the measurement interval in response to changes in the rotational speed of the rotating component.

[0013] According to any one or more of the above-described embodiments, the rotational frequency is a first rotational frequency, and the frequency processor is further operable to determine a second rotational frequency of the rotating component concurrently with determining the first rotational frequency, and the frequency processor is further operable to determine the second rotational frequency using a second difference between the second most recent count value and the second immediately preceding count value and a second measurement window, and optionally, the frequency processor is further operable to generate a resulting rotational frequency using the first rotational frequency and the second rotational frequency. According to any one or more of the above-described embodiments, the frequency processor is further operable to calculate an optimal size of the measurement window using one or more of a minimum rotational frequency, a maximum rotational frequency, a measurement interval, and an error rate of the rotating component. According to any one or more of the above-described embodiments, the variable divider is configured to provide pulses to the counter, the pulses provided by the variable divider corresponding to a plurality of protrusions of the rotating component, and optionally, the frequency processor is further operable to calculate an optimal frequency division value for the variable divider using one or more of a minimum rotational frequency, a maximum rotational frequency, a measurement interval, and an error rate of the rotating component.

[0014] A more particular description of the present disclosure, briefly summarized above, will be obtained by reference to various embodiments, some of which are illustrated in the accompanying drawings. While the accompanying drawings illustrate selected embodiments of the present disclosure, these drawings should not be considered as limiting the scope of the present disclosure, as the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram illustrating an exemplary system for measuring the rotational frequency of a rotating machine in accordance with an embodiment of the present disclosure. [Figure 2] FIG. 4 is a timing diagram illustrating an exemplary method for measuring rotation frequency in accordance with an embodiment of the present disclosure. [Figure 3A] FIG. 1 is a functional diagram illustrating an exemplary method for measuring rotational frequency, in accordance with an embodiment of the present disclosure. [Figure 3B] FIG. 1 is a functional diagram illustrating an exemplary method for measuring rotational frequency, in accordance with an embodiment of the present disclosure. [Figure 3C] FIG. 1 is a functional diagram illustrating an exemplary method for measuring rotational frequency, in accordance with an embodiment of the present disclosure. [Figure 3D] FIG. 1 is a functional diagram illustrating an exemplary method for measuring rotational frequency, in accordance with an embodiment of the present disclosure. [Figure 4] FIG. 1 is a functional diagram illustrating an exemplary method for measuring rotational frequency, in accordance with an embodiment of the present disclosure. [Figure 5] FIG. 10 is a functional diagram illustrating an alternative method for measuring rotational frequency in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] Wherever possible, the same reference numerals have been used to designate identical elements common to the figures, however, elements disclosed in one embodiment may be beneficially utilized on other embodiments without repetition of specific description.

[0017] Referring now to FIG. 1 , a schematic diagram of an exemplary system 100 for measuring the rotational frequency of a rotating machine 102 is shown in accordance with an embodiment of the present disclosure. The rotating machine 102 in this example may be any type of machine that uses a rotating component, such as a gear 104, having a known number of projections, such as gear teeth 106, thereon and that rotates about a shaft 108 or other axis during operation of the rotating machine 102. Such rotating machines 102 may include various turbines (e.g., steam turbines, gas turbines, hydroelectric turbines, wind turbines), internal combustion engines, electric motors, generators, compressors, and other machines that use or have rotating components. A pulse generator 110 is mounted proximate to the gear 104 to detect the gear teeth 106. The pulse generator 110 may be a mechanical, magnetic, optical, or any suitable rotational 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. The rotational frequency, typically provided in revolutions per minute (rpm), may then be used by various systems, such as control system 114 and / or overspeed protection system 116, to control the operation of rotating machinery 102.

[0018] In the example of FIG. 1 , rotational frequency measurement circuit 112 processes the pulse signal and determines the rotational frequency using multiple components. These components, shown here as functional blocks, include, among other components, a clock 118, a counter 120, a memory 122, and a frequency processor 124. Generally, clock 118 provides an internal clock signal that serves as an internal time base, and counter 120 operates to count clock cycles of the clock signal. Memory 122 stores the counts from counter 120, and frequency processor 124 uses the stored counts to determine the rotational frequency of gear 104. Preferably, rotational frequency measurement circuit 112 (or one or more components thereof) is implemented using programmable logic, such as a microprocessor, a programmable logic controller (PLC), or a field programmable gate array (FPGA).

[0019] 2 is a timing diagram illustrating the operation of some of the above components, in accordance with an embodiment of the present disclosure. In this example, Clock is an internal clock signal provided by Clock 118, Pulse is a pulse input signal provided by Pulse Generator 110, and Measurement Interval is a preselected time interval 128 during which clock cycles are counted to determine the rotation frequency. Memory 122 resembles a circular buffer or queue with a series of data registers 126 that are filled sequentially, wrapping around to the first data register when the filling process needs to be restarted. Each data register is labeled n for reference. q where "q" specifies the register index number (i.e., q=0 is the first data register, q=1 is the second data register, etc.).

[0020] In operation, the first rising edge of the pulse input signal within a measurement interval 128 starts / resets the counter 120 to begin counting clock cycles of the internal clock signal. That first rising edge (and each subsequent rising edge) also prompts the counter 120 to output a current raw counter value 130 to the memory 122, which captures that counter value 130 in the first data register n0 as Count0. The second rising edge of the pulse input signal prompts the counter 120 to output a next counter value 132 to the memory 122, which captures the next counter value 132 in the next data register n1 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 rewinds to the first data register n0 to store a new current counter value 134 in the new measurement interval 128. Therefore, the memory 122 must have a sufficient number of data registers 124 to hold each captured counter value in a separate data register for a measurement interval 128 of a given length.

[0021] 3A-3D are functional diagrams illustrating the operation of rotational frequency measurement circuit 112, and in particular frequency processor 124, in accordance with an embodiment of the present disclosure. In these examples, gear 104 is assumed to have 60 teeth, causing pulse generator 110 to generate 60 pulses per revolution.

[0022] 3A, in some embodiments, frequency processor 124 determines the rotation frequency by taking the count difference D between the most recent counter value, assumed to be, for example, Count3 (i.e., q=4), and some selected immediately preceding counter value, assumed to be, for example, Count1 (i.e., q=2). Frequency processor 124 then uses this count difference D to calculate the rotation frequency using the following equation:

number

[0023] In the above equation (1), 60 is the time conversion factor (i.e., 60 seconds / minute), T is the time period of the clock signal, G is the number of pulses per revolution generated by the gear teeth, and p is the measurement window reflecting the difference in the number of pulse input signals between the two counter values ​​(i.e., Count3 and Count1) that make up D. In this example, the measurement window p has a value of 2 pulses (i.e., 3 - 1 = 2), and G has a value of 60 pulses / revolution. From Figure 2, if we can assume that each clock cycle is 100 μsec and there are 10 clock cycles in each pulse input signal, the time period T of the clock signal is 0.0001 seconds / cycle, and the value of D is 20 cycles (i.e., 30 - 10 = 20). The resulting RPM is approximately 1,000 rpm (i.e., (2 pulses × 60 seconds / minute) / (20 cycles × 0.0001 seconds / cycle × 60 pulses / revolution)).

[0024] 3B shows the rotational frequency measurement circuit 112 sliding the 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, current Count4, and the new previous counter value, current Count2. In this manner, the rotational frequency measurement circuit 112 can continuously and quickly capture changes in the rotational frequency of the gear 104, as any changes 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 foregoing arrangement also allows the rotational frequency measurement circuit 112 to experience very low latency, as new / updated rotational frequency measurements are determined using the existing, previously captured counter value. Low latency is particularly important for certain applications requiring extremely fast measurement response times, such as overspeed detection systems (ODS) and similar applications.

[0025] 3C, the rotational frequency measurement circuit 112 can dynamically change the size of the measurement sliding window p from measurement to measurement as needed depending on the particular application. For example, as the rotational frequency of the gear 104 changes, the sliding window p (e.g., 2 pulses) can be increased or decreased to p′ (e.g., 1 pulse, 3 pulses, etc.). Such a variable sliding window can better maintain accuracy when the rotational speed of the gear 104 is changing, such as when the gear 104 is rotating and the rotational speed is detected to be accelerating. In that case, the sliding window may be dynamically decreased to shorten response time. Conversely, when the gear 104 is decelerating and the rotational speed is detected to be slowing down, the sliding window may be dynamically increased to improve accuracy. In some embodiments, the sliding window p may be a multiple of G (e.g., 2 G, 3 G, 4 G, etc.), in which case a sliding window extending beyond one rotation of the gear is desired (e.g., p=60, 120, 180, 240, etc.).

[0026] Furthermore, as shown in FIG. 3D , the rotational frequency measurement circuit 112 can perform multiple rotational frequency measurements in parallel using multiple measurement sliding windows. 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 RPM1, while simultaneously using a second measurement window p2 to obtain a second count difference D2 and a rotational frequency measurement RPM2. The two measurement sliding windows may partially overlap each other in some embodiments, or may remain separate in some embodiments. These parallel measurements may be performed using a sufficiently large circular buffer (e.g., an FPGA) as the memory 122 to accommodate the additional counts, especially if the sliding windows do not overlap. The rotational frequency measurement circuit 112 may then apply a mathematical function, such as an averaging function, to the two rotational frequency measurements RPM1 and RPM2 to generate a resulting rotational frequency measurement (i.e., RPM = (RPM1 + RPM2) / 2). Alternatively, the rotation frequency measurement circuit 112 may simply select the most recent of the two measurements to use as the rotation frequency measurement.

[0027] In the above-described embodiments, a window size algorithm or model can be developed to dynamically predict the optimal sliding window size p to be used for a given measurement. The model, which may be in the form of an equation in some embodiments, may be developed using statistical and numerical techniques known to those skilled in the art, including the application of machine learning to rotational frequency measurement data collected over time. Such a model may be configured based, at least in part, on the desired minimum and maximum rotational frequencies for a given rotating machine application, the desired measurement interval for the application, and / or the maximum error rate for the application, among other configuration parameters. This model may then be incorporated into the rotational frequency measurement circuit and used to dynamically calculate the optimal sliding window size to be used for a given rotational frequency measurement. This allows the rotational frequency measurement circuit to adapt the sliding window size with consistent accuracy across the desired rotational frequency range, even within the same measurement interval. In this way, the rotational frequency measurement circuit can begin restoring high accuracy as quickly as the next rotational frequency measurement when the application's rotational frequency changes.

[0028] 4 is a functional diagram illustrating an example method 400 that may be used with a rotational frequency measurement circuit to measure rotational frequency using a dynamically calculated, model-based measurement sliding window. Method 400 generally begins at block 402, where a minimum frequency, a maximum frequency, a measurement interval, and a maximum error rate are selected for the rotational frequency measurement circuit, if not previously done so. At block 404, if not previously done so, an appropriate clock frequency is selected for the rotational frequency measurement circuit based on input from block 402, and the sliding window size is set to an initial value, e.g., p=1. At block 406, if not previously done so, the number of gear teeth (i.e., the number of pulses per revolution) is selected.

[0029] At block 408, the clock signal frequency is set using the clock frequency selection from block 404, and at block 410, the next window size (i.e., the number of pulse input signals) for the rotation frequency measurement circuit is set. Initially, this window size may be the initial window size selected at block 404, but may thereafter be calculated using an algorithm or model similar to that described above. The pulse input signal is provided at block 412. Any signal conditioning that may be required is provided at block 414. The rotation frequency measurement circuit then determines the rotation frequency as described above at block 416 (see equation (1)) and outputs the rotation frequency at block 418. The rotation frequency is also provided as feedback to block 410, so that the rotation frequency measurement circuit dynamically calculates the next window size using an algorithm or model therein.

[0030] 5 is a functional diagram illustrating an example method 500 that may be used with a rotational frequency measurement circuit to measure rotational frequency using a frequency divider to divide the frequency of a pulsed input signal. As shown at 501, the frequency divider generates a divided signal in which a single pulse of the divided signal reflects or corresponds to multiple pulses of the original pulsed input signal over a given measurement interval, depending on the size of the divider. Such an arrangement reduces implementation complexity by avoiding the need to sample each individual pulse of the original pulsed input signal over the measurement interval.

[0031] Method 500 generally begins at block 502, where, similar to above, a minimum frequency, a maximum frequency, a measurement interval, and a maximum error rate are selected for the rotational frequency measurement circuit, if not previously done so. At block 504, if not previously done so, an appropriate clock frequency is selected for the rotational frequency measurement circuit based on the input from block 502, and the divider size is set to an initial value, e.g., divider=1. At block 506, if not previously done so, the number of gear teeth (i.e., number of pulses per revolution) is selected.

[0032] At block 508, the clock signal frequency is set using the clock frequency selection from block 504, and at block 510, the next divide value is set. This divide value may be the initial divide value selected at block 504, or may subsequently be calculated using an algorithm or model similar to that described above. A pulse input signal is provided at block 512. Any signal conditioning that may be required is provided at block 514. The conditioned pulse input signal is then divided at block 516 using the divide value from block 510 (initial value is 1). The divided signal is then used by a rotation frequency measurement circuit to determine the rotation frequency at block 516 (e.g., using equation (1) modified to account for the divided signal). The rotation frequency measurement circuit then outputs the rotation frequency at block 518 and provides the rotation frequency as feedback to block 510. At block 510, the rotation frequency measurement circuit dynamically calculates the next divide value using an algorithm or model therein.

[0033] The above-described embodiments offer many advantages over existing rotational speed measurement systems and methods. These advantages include a dynamically configurable parametric measurement model driven by frequency range, accuracy, and measurement interval. A further advantage includes a sliding, variable-size window design that provides low-latency measurements on demand. A further advantage includes a method for achieving consistently high-accuracy rotational speed measurements within the same measurement interval across a frequency range. Yet another advantage includes a method for restoring full measurement accuracy at the next measurement interval if the rotation frequency changes. In this way, measurement errors are controlled and minimized, even under abnormal and extreme conditions. These further advantages include high-speed parallel measurements at low frequencies that provide stable results, making the system particularly useful for AC frequency and phase difference measurements and power factor correction in power generation, or any other application where accurate, high-speed measurement of rotational speed is required.

[0034] The foregoing description refers to various embodiments. However, the scope of the present disclosure is not limited to the specific embodiments described. Instead, any combination of the described features and elements, whether associated with different embodiments or not, is contemplated for implementing and practicing the contemplated embodiments. Moreover, while embodiments may achieve advantages over other possible solutions or prior art, whether or not a particular advantage is achieved by a given embodiment does not limit the scope of the present disclosure. Accordingly, the above-described aspects, features, embodiments, and advantages are merely exemplary and should not be considered elements or limitations of the appended claims unless expressly recited in the claims.

[0035] Various embodiments disclosed herein may be implemented as a system, method, or computer program product. Accordingly, aspects may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be referred to generally herein as a "circuit," "module," or "system." Furthermore, aspects may take the form of a computer program product embodied in one or more computer-readable medium(s) having computer-readable program code embodied therein.

[0036] Any combination of one or more computer-readable media may be utilized. The computer-readable medium may be a non-transitory computer-readable medium. The non-transitory computer-readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples (non-exhaustive list) of non-transitory computer-readable media may include, for example, an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. The program code embodied on the computer-readable medium may be transmitted using any suitable medium. Any suitable medium includes, but is not limited to, wireless, wired, fiber optic cable, RF, or the like, or any suitable combination thereof.

[0037] Computer program code for performing operations for aspects of the present disclosure may be written in any combination of one or more programming languages. Furthermore, such computer program code may be executed using a single computer system or multiple computer systems in communication with each other (e.g., using a local area network (LAN), a wide area network (WAN), the Internet, etc.). While various features described above have been described with reference to flowchart diagrams and / or block diagrams, those skilled in the art will understand that each block of the flowchart diagrams and / or block diagrams, and combinations of blocks in the flowchart diagrams and / or block diagrams, may be implemented by computer logic (e.g., computer program instructions, hardware logic, combinations thereof, etc.). Generally, computer program instructions may be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing device. Furthermore, execution of such computer program instructions using a processor produces a machine capable of performing the functions or acts specified in one or more blocks of the flowchart diagrams and / or block diagrams.

[0038] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and / or operation of possible implementations of various embodiments of the present disclosure. In this regard, each block in the flowcharts or block diagrams may represent a module, segment, or portion of code, constituting one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative embodiments, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may be executed in the reverse order, depending on the functionality involved. It should also be noted that each block in the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a special-purpose hardware-based system that performs a specified function or act, or a combination of special-purpose hardware and computer instructions.

[0039] It should be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will become apparent upon reading and understanding the above description. While the present disclosure describes particular embodiments, it is recognized that the systems and methods of the present disclosure are not limited to the embodiments described herein, but may be practiced with modification within the scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A rotational frequency measurement circuit, a counter configured to count clock cycles of a clock signal during a measurement interval, the counter operable to output a count value upon receiving a pulse, the pulse corresponding to at least one of a plurality of protrusions on a rotating component of a rotating machine, the count value representing a number of clock cycles that have elapsed since the start of the measurement interval; a memory coupled to the counter and configured to receive a plurality of count values ​​from the counter during the measurement interval, the memory operable to individually sequentially store each count value during the measurement interval; a frequency processor coupled to the memory, the frequency processor operable to determine a rotational frequency of the rotating component using a difference between a most recent count value and a selected immediately preceding count value and a measurement window, the measurement window representing the number of pulses occurring between the most recent count value and the immediately preceding count value during the measurement interval; Equipped with the counter is configured to reset at the beginning of a new measurement interval, the measurement interval being a preselected time interval including a plurality of measurement windows; the frequency processor is further operable to slide the measurement window to a next most recent count value and a next selected immediately preceding count value in the memory so that the most recent count value falls within the slid measurement window, and to determine the rotational frequency of the rotating component using the difference between the next most recent count value and the next selected immediately preceding count value and the slid measurement window.

2. 2. The rotational frequency measurement circuit of claim 1, wherein the memory is a circular buffer configured to begin a new sequence of stored counter values ​​at the start of a new measurement interval.

3. 2. The rotational frequency measurement circuit of claim 1, wherein the frequency processor is further operable to slide the measurement window to a next most recent count value and a next immediately preceding count value in the memory, and to determine the rotational frequency of the rotating component using the difference between the next most recent count value and the next immediately preceding count value and the measurement window.

4. 2. The rotational frequency measurement circuit of claim 1, wherein the frequency processor is further operable to vary the size of the measurement window during the measurement interval in response to changes in the rotational speed of the rotating component.

5. 2. The rotational frequency measurement circuit of claim 1, wherein the rotational frequency is a first rotational frequency, and the frequency processor is further operable to determine a second rotational frequency of the rotating component simultaneously with determining the first rotational frequency, and wherein the frequency processor determines the second rotational frequency using a second difference between a second most recent count value and a second immediately preceding count value and a second measurement window.

6. The rotational frequency measurement circuit of claim 5 , wherein the frequency processor is further operable to generate a third rotational frequency using the first rotational frequency and the second rotational frequency.

7. 2. The rotational frequency measurement circuit of claim 1, wherein the frequency processor is further operable to calculate an optimal size of the measurement window using one or more of a minimum rotational frequency, a maximum rotational frequency, a measurement interval, and an error rate of the rotating component.

8. 2. The rotational frequency measurement circuit of claim 1, further comprising a variable divider configured to provide the pulses to the counter, the pulses provided by the variable divider corresponding to a plurality of protrusions on the rotating component.

9. 9. The rotational frequency measurement circuit of claim 8, wherein the frequency processor is further operable to calculate an optimal frequency division value for the variable frequency divider using one or more of a minimum rotational frequency, a maximum rotational frequency, a measurement interval, and an error rate of the rotating component.

10. A method for measuring rotational frequency, comprising: receiving a pulse during a measurement interval with a counter, the counter configured to count clock cycles of a clock signal during the measurement interval, the pulse corresponding to at least one of a plurality of protrusions of a rotating component of a rotating machine; outputting a count value at the counter upon receiving the pulse, the count value representing the number of clock cycles that have elapsed since the beginning of the measurement interval; receiving, in a memory coupled to the counter, a plurality of count values ​​from the counter during the measurement interval; storing each count value received from the counter individually and sequentially in the memory during the measurement interval; determining, in a frequency processor coupled to the memory, the rotational frequency of the rotating component using a difference between a most recent count value and a selected immediately preceding count value and a measurement window, the measurement window representing the number of pulses occurring between the most recent count value and the immediately preceding count value during the measurement interval; Including, the counter is configured to reset at the beginning of a new measurement interval, the measurement interval being a preselected time interval including a plurality of measurement windows; sliding the measurement window in the frequency processor to the next most recent count value and the next selected immediately preceding count value in the memory so that the most recent count value is included in the sliding measurement window; determining, in the frequency processor, the rotational frequency of the rotating component using the difference between the next most recent count value and the next selected previous count value and the sliding measurement window; The measuring method further comprises:

11. 11. The measurement method of claim 10, wherein the memory is a circular buffer, and further comprising the step of storing a new sequence of counter values ​​in the circular buffer at the start of a new measurement interval.

12. 11. The method of claim 10, further comprising the steps of: sliding a measurement window in the frequency processor to a next most recent count value and a next previous count value in the memory; and determining in the frequency processor the rotational frequency of the rotating component using the difference between the most recent count value and a selected previous count value and the measurement window.

13. The method of claim 10 further comprising the step of varying, at the frequency processor, a size of the measurement window during the measurement interval in response to changes in the rotational frequency of the rotating component.

14. the rotational frequency is a first rotational frequency, 11. The method of claim 10, further comprising the step of determining with the frequency processor a second rotational frequency of the rotating component simultaneously with determining the first rotational frequency, the frequency processor determining the second rotational frequency using a second difference between a second most recent count value and a second immediately preceding count value and a second measurement window.

15. The method of claim 14 further comprising generating, in the frequency processor, a third rotational frequency using the first rotational frequency and the second rotational frequency.

16. 11. The measurement method of claim 10, further comprising the step of calculating, in the frequency processor, an optimal size of the measurement window using one or more of a minimum rotational frequency, a maximum rotational frequency, a measurement interval, and an error rate of the rotating component.

17. 11. The method of claim 10, further comprising the step of providing the pulses to the counter with a variable divider, the pulses provided by the variable divider corresponding to a plurality of protrusions on the rotating component.

18. 18. The measurement method of claim 17, further comprising the step of calculating, with the frequency processor, an optimal frequency division value for the variable frequency divider using one or more of a minimum rotational frequency, a maximum rotational frequency, a measurement interval, and an error rate of the rotating component.

Images