CN111834079B

CN111834079B - Solenoid plunger movement detection system

Info

Publication number: CN111834079B
Application number: CN202010294932.7A
Authority: CN
Inventors: R·卡西拉奇; L·弗兰基尼; P·因特罗伊尼
Original assignee: Maxim Integrated Products Inc
Current assignee: Maxim Integrated Products Inc
Priority date: 2019-04-15
Filing date: 2020-04-15
Publication date: 2023-04-14
Anticipated expiration: 2040-04-15
Also published as: CN111834079A

Abstract

A solenoid plunger movement detection system and method may include: detecting a current supplied to the solenoid using a current sensor; converting the current supplied to the solenoid into a digital signal using a counter coupled to a first comparator; detecting a peak within the digital signal with a peak detector; comparing the peak value to the digital signal with a second comparator coupled to the peak detector; measuring a dip from the peak with the second comparator and measuring a valley; generating an error when the peak and the valley indicate a smooth current rise of the solenoid; receiving, with a signal processor, configurable parameters for processing the digital signal; and providing configurable parameters to the counter, the second comparator, the signal processor, or a combination thereof using an interface.

Description

Solenoid plunger movement detection system

Cross Reference to Related Applications

The present invention claims priority benefits to all common subject matter of U.S. provisional patent application No. 62/833,896 filed on 15/4/2019. The contents of this U.S. provisional application are hereby incorporated by reference in their entirety.

Technical Field

The present disclosure relates to solenoids, and more particularly to detecting moving properties of a solenoid.

Background

Rapid automation in industries including manufacturing, healthcare, and automotive relies heavily on solenoids. Solenoids may be found in automatic locking mechanisms such as office, hotel, and high security area door locks.

Electronic solenoids are also important in the medical field where precise and accurate movements are required, such as during the operation of dialysis machines and drug dispensers. Industrial manufacturing may require precise actuation of tens or hundreds of solenoids, such as in textile manufacturing systems.

When the solenoid valve fails to operate properly, it is often due to the plunger becoming stuck. When used in industrial manufacturing, failure of one solenoid can affect the quality of the product, can stop the production line, and even present a hazard to the operator. When used in the medical or safety industry, failure of the solenoid can result in loss of life.

Timely and affordable detection of such faults is highly desirable. The movement detection mechanisms for solenoids have unique attributes that significantly impact manufacturing integration, as they typically must be small, lightweight, and versatile, and they must be mass produced at relatively low cost.

As an extension of the electronics industry, the electronic solenoid industry has witnessed increasing commercial competitive pressures, as well as increasing consumer expectations and a reduction in opportunities for meaningful product differentiation in the marketplace.

Electronic detection of solenoid motion attributes is central to next generation electronics insertion strategies outlined in the development roadmap for next generation products. In addition to the performance requirements of next generation equipment, the industry now requires cost to be a major product differentiation factor to achieve profit goals.

There have previously been methods for addressing the requirements for control and detection of solenoid motion attributes. Industry roadmaps have identified significant gaps between current capabilities and available supporting electronic detection technologies.

One such prior approach for detecting solenoid motion attributes relies on operational amplifiers, comparators, and active peak detectors. However, this approach is expensive, consumes a lot of power, and is not easily configurable.

In view of the ever-increasing commercial competitive pressures and the ever-increasing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found to these problems. In addition, the need to reduce cost, reduce power requirements, provide configurability, and meet competitive pressures makes the critical necessity of finding answers to these problems even more acute.

Thus, there remains a need for accurate, low cost, highly configurable control and detection of solenoid motion attributes with significantly lower power requirements. Solutions to these problems have long been sought but prior developments have not taught or suggested any solutions and, therefore, solutions to these problems have long eluded those skilled in the art.

Drawings

The detection system is illustrated in the accompanying drawings, which are meant to be exemplary and not limiting, in which like references are intended to refer to like parts, and in which:

fig. 1 is a block diagram of a detection system 100 in a first embodiment.

Fig. 2 is a graphical depiction of the current detected by the current sensor of fig. 1.

Fig. 3 is a block diagram of a detection system 300 in a second embodiment.

FIG. 4 is a control flow for detecting solenoid plunger movement with the detection system.

Detailed Description

In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration embodiments in which the detection system may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the detection system.

While features, aspects, or embodiments of the detection system are described in terms of processes, operations, control flows, or steps of flowcharts, it should be understood that the steps may be combined, performed in a different order, deleted, or include additional steps without departing from the detection system as described herein.

The detection system is described in sufficient detail to enable those skilled in the art to make and use the detection system and to provide many specific details for a thorough understanding of the detection system; it will be apparent, however, that the detection system may be practiced without these specific details.

Some well known system configurations and descriptions are not disclosed in detail to avoid obscuring the detection system. Likewise, the drawings showing embodiments of the system are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown exaggerated in the drawing figs.

In general, the detection system may operate in any orientation. As used herein, the term "couple" or "coupled" refers to an electrical connection between components. The term "system" refers to a machine or apparatus.

Referring now to FIG. 1, there is shown a block diagram of a detection system 100 in a first embodiment. The detection system 100 may include a solenoid 102.

The solenoid 102 is depicted as a single solenoid, however, it should be understood that the solenoid 102 represents one or many solenoids. The solenoid 102 may be, for example, a linear solenoid, also referred to as a linear electromechanical actuator. The solenoid 102 may include an electrical coil wrapped around a cylindrical tube within a solenoid body 104 and a magnetic actuator or plunger 106.

The plunger 106 is free to move or slide into and out of the body 104 of the solenoid 102. When current is passed through the coil within the body 104 of the solenoid 102, the coil behaves like an electromagnet, and a plunger 106 located inside the coil is attracted toward the center of the coil by the magnetic flux established within the coil.

As the plunger 106 moves toward the center of the body 104, the plunger 106 may compress a small spring located within the body 104 of the solenoid 102 and attached to one end of the plunger 106. The force and speed of movement of the plunger 106 is determined by the strength of the magnetic flux generated within the coil.

When the supply current is switched off, the electromagnetic field generated by the coil will disappear, thereby releasing the plunger 106 and allowing the compressed spring to force the plunger 106 back to its starting rest position. The solenoid 102 may be coupled to a power source 108.

The power source 108 may supply the current required to actuate the plunger 106 into and out of the body 104 of the solenoid 102. Between the solenoid 102 and the power source 108, the detection system 100 may include a current sensor 110.

The current sensor 110 may detect and output a current as represented in fig. 2 that is supplied to the solenoid 102. The current sensor 110 may detect the amount of current supplied from the power source 108 to the solenoid 102. The current sensor 110 may indicate the detected current as an analog output value. The output of the current sensor 110 may be coupled to a current comparator 112.

The current comparator 112 may be, for example, a component within the current driven regulation loop 114. The current drive regulation loop 114 may ensure that a controlled amount of current is supplied to the solenoid 102.

The current drive regulation loop 114 may include regulation components 116 including passive components such as resistors, capacitors, and inductors, as well as active components such as transistors. The output of the current-driven regulation loop 114 may be supplied to the power supply 108.

It has been found that using the same current comparator 112 as part of the current driven regulation loop 114 and as part of the detection system 100 reduces the number of parts, reduces the footprint, reduces the complexity of the design, and, importantly, reduces the cost.

The current comparator 112, together with an up/down counter 118 and a digital-to-analog converter or current digital-to-analog converter (DAC) 120, may track the current detected by the current sensor 110. An up/down counter 118 coupled to the current comparator 112 and to a current DAC 120 may operate to convert the current supplied to the solenoid into a digital signal. Illustratively, for example, the current comparator 112 may include two analog inputs, one from the current sensor 110 and the other from the current DAC 120.

The output of the current comparator 112 may be a digital signal indicating whether the most recently detected current from the current sensor 110 is above or below the previously detected current provided by the output of the current DAC 120. The output of the current comparator 112 may be supplied to an up/down counter 118.

The up/down counter 118 may generate and supply a digital representation of the current detected by the current sensor 110 by incrementing or decrementing a count based on the output supplied by the current comparator 112. The current DAC 120 may then convert the digital representation of the current supplied by the up/down counter 118 to an analog representation of the current.

The analog representation of the current from the current DAC 120 may then be supplied to the current comparator 112 for comparison with the most recently detected current from the current sensor 110. The digital signal output from the up/down counter 118 may be supplied to both the digital peak detector 122 and the digital comparator 124.

The digital peak detector 122 may include a register for holding and supplying the maximum digital output from the up/down counter 118, which is detected during the period of the current solenoid 102. The maximum digital output from the up/down counter 118 may correspond to the peak value 206 of fig. 2.

The up/down counter 118 may supply a subsequent digital representation of the current to the digital comparator 124. For example, the subsequent digital representation of the current may be one or many clock cycles after the digital peak detector 122 latches to the peak 206.

Thus, the digital comparator 124 may compare the peak 206 with the digital output from the up/down counter 118 at a later time. This comparison by the digital comparator 124 may measure the difference between the peak 206 and the subsequent digital output from the up/down counter 118.

Illustratively, this difference may be the difference between the peak 206 and the valley 210 of fig. 2, for example. The digital comparator 124 may include a falling amplitude threshold 126.

The drop amplitude threshold 126 may be a threshold of the difference between the peak 206 and the valley 210. If the difference between the peak 206 and the valley 210 (as determined by the digital comparator 124) is greater than the drop amplitude threshold 126, then proper movement of the plunger 106 is detected.

When the difference between the peak 206 and the valley 210 (as determined by the digital comparator 124) is less than the drop amplitude threshold 126, then proper movement of the plunger 106 is not detected and an error is generated. The digital comparator 124 may output a fault when the difference between the peak 206 and the valley 210 is less than the falling amplitude threshold 126. In an extreme case, when the difference between the peak 206 and the valley 210 is small, the peak 206 and the valley 210 will be smooth, as shown in the incorrect current rise curve 204, and this indicates a smooth and incorrect current rise of the solenoid 104.

It has been found that determining and processing peaks 206, dips 208, and valleys 210 in the digital domain provides reduced power consumption, reduced cost, and better configurability as compared to motion detection in the analog domain that suffers from low configurability, high power dissipation, and high cost. Further, it has been found that detected errors reported by the detection system 100 can provide timely and affordable detection of improper plunger 106 movement, which is highly desirable in many industries, including the manufacturing industry, the healthcare industry, and the automotive industry.

Referring now to FIG. 2, a graphical depiction of the current detected by the current sensor 110 of FIG. 1 is shown. The current sensor 110 may detect a current rise in the current provided to the solenoid 102 of fig. 1.

For illustrative purposes, the current detected by the current sensor 110 may be depicted as a correct current rise curve 202 and an incorrect current rise curve 204. The correct current rise curve 202 may be generated by the plunger 106 of fig. 1 moving within the solenoid 102.

That is, a correct current rise curve 202 may indicate a solenoid 102 that is functioning properly. The correct current rise curve 202 may include a peak 206 and a dip 208.

The dip 208 that causes the peak 206 to occur may be caused by the instantaneous back electromotive force (BEMF) generated by the movement of the plunger 106 inside the solenoid 102. The incorrect current rise curve 204 is shown as being smooth, with the dip 208 and peak 206 eliminated within the incorrect current rise curve 204. This smoothed current rise indicates that the plunger 106 is not moving within the solenoid 102.

The peak 206 of the correct current rise curve 202 may indicate when the motion of the plunger 106 begins. The plunger 106 will continue to move through the drop 208, which will end at a valley 210.

The valley 210 may indicate when the plunger 106 has finished its motion. Once the plunger 106 has finished its motion, the correct current rise curve 202 may continue to rise to the maximum current 212.

Referring now to FIG. 3, there is shown a block diagram of a detection system 300 in a second embodiment. The detection system 300 may include a solenoid 302.

The solenoid 302 is depicted as a single solenoid, however, it should be understood that the solenoid 302 represents one or many solenoids. The solenoid 302 may be, for example, a linear solenoid, also referred to as a linear electromechanical actuator.

The solenoid 302 may include an electrical coil wrapped around a cylindrical tube within a solenoid body 304 and a magnetic actuator or plunger 306.

The plunger 306 is free to move or slide into and out of the body 304 of the solenoid 302. When current is passed through the coil within the body 304 of the solenoid 302, the coil behaves like an electromagnet, and a plunger 306 located inside the coil is attracted toward the center of the coil by the magnetic flux established within the coil.

As the plunger 306 moves toward the center of the body 304, the plunger 306 may compress a small spring located within the body 304 of the solenoid 302 and attached to one end of the plunger 306. The force and speed of movement of the plunger 306 is determined by the strength of the magnetic flux generated within the coil.

When the supply current is switched off, the electromagnetic field generated by the coil will disappear, thereby releasing the plunger 306 and allowing the compressed spring to force the plunger 306 back to its starting rest position. The solenoid 302 may be coupled to a power source 308.

The power source 308 may supply the current required to actuate the plunger 306 into and out of the body 304 of the solenoid 302. Between the solenoid 302 and the power source 308, the detection system 300 may include a current sensor 310.

The current sensor 310 may detect and output the current as represented in fig. 2 supplied to the solenoid 302. The current sensor 310 may detect the amount of current supplied to the solenoid 302 from the power source 308. The current sensor 310 may indicate the detected current as an analog output value. The output of the current sensor 310 may be coupled to a current comparator 312.

The current comparator 312 may, for example, be part of a current driven regulation loop 314. The current drive regulation loop 314 may ensure that a controlled amount of current is supplied to the solenoid 302.

The current drive regulation loop 314 may include regulation components 316, including passive components such as resistors, capacitors, and inductors, as well as active components such as transistors. The output of the current drive regulation loop 314 may be supplied to the power supply 308.

It has been found that utilizing the same current comparator 312 as part of the current driven regulation loop 314 and as part of the detection system 300 reduces part count, reduces footprint, reduces design complexity, and, importantly, reduces cost.

The current comparator 312, along with an up/down counter 318 and a digital-to-analog converter or current DAC 320, may track the current detected by the current sensor 310. Illustratively, for example, current comparator 312 may include two analog inputs, one from current sensor 310 and the other from current DAC 320.

The output of the current comparator 312 may be a digital signal indicating whether the most recently detected current is higher or lower than the previously detected current. The output of the current comparator 312 may be supplied to an up/down counter 318.

The up/down counter 318 may generate and supply a digital representation of the current detected by the current sensor 310 by counting up or down based on the output supplied by the current comparator 312. The current DAC 320 may then convert the digital representation of the current supplied by the up/down counter 318 to an analog representation of the current.

The analog representation of the current from current DAC 320 may then be supplied to current comparator 312 for comparison with the most recently detected current from current sensor 310. The digital output from the up/down counter 318 may be supplied to both a digital peak detector 322 and a digital comparator 324.

The digital peak detector 322 may include a register for holding and supplying the maximum digital output from the up/down counter 318 that is detected during the period of the current solenoid 302. The maximum digital output from the up/down counter 318 may correspond to the peak 206 of fig. 2.

The up/down counter 318 may supply a subsequent digital representation of the current to the digital comparator 324 for comparison with the peak 206 supplied by the digital peak detector 322. For example, the subsequent digital representation of the current may be one or many clock cycles after the digital peak detector 322 latches to the peak 206.

Thus, the digital comparator 324 may compare the peak 206 with the digital output from the up/down counter 318 at a later time. This comparison by the digital comparator 324 may measure the difference between the peak 206 and the subsequent digital output from the up/down counter 318. Illustratively, this difference may be the difference between the peak 206 and the valley 210 of fig. 2, for example.

It has been found that determining the peaks 206, dips 208 and valleys 210 in the digital domain provides reduced power consumption, reduced cost and better configurability compared to motion detection in the analog domain which suffers from low configurability, high power dissipation and high cost.

The up/down counter 318 and the digital comparator 324 may have a digital interface 326 coupled thereto. Digital interface 326 may provide an interface, such as a serial peripheral interface, for providing user configurable parameters; however, other digital interfaces may be used without departing from the disclosed detection system 300.

Illustratively, the digital interface 326 may provide the up/down counter 318 with a user-configurable start/end threshold 328. The start/end threshold 328 may be a threshold for the up/down counter 318 that is used to determine when the up/down counter 318 will start and end its operations described above. Implementing the start/end threshold 328 within the up/down counter 318 may rely on a clock input to the up/down counter 318 to convert the current supplied to the solenoid to a digital signal only during the time between start/end thresholds.

Additionally, the start/end threshold 328 may be used to identify incorrect plunger movement associated with the solenoid 302 that requires repair or replacement. The digital interface 326 may also supply a programmable drop amplitude threshold 330 to the digital comparator 324.

The drop amplitude threshold 330 may be a threshold of the difference between the peak 206 and the valley 210. If the difference between the peak 206 and the valley 210 (as determined by the digital comparator 324) is greater than the drop amplitude threshold 330, movement of the plunger 306 is detected.

When the difference between the peak 206 and the valley 210 (as determined by the digital comparator 324) is less than the drop amplitude threshold 330, then no movement of the plunger 306 is detected and an error is generated. Digital interface 326 may further provide a plurality of configurable parameters to digital signal processor 332. As will be appreciated, the digital interface 326 may provide these configurable parameters to the up/down counter 318, the digital comparator 324, the digital signal processor 332, or a combination thereof.

Illustratively, the digital signal processor 332 may provide digital processing for the signal output from the digital comparator 324, or in another contemplated embodiment, for a digital representation of the current from the up/down counter 318, for example. The digital signal processor 332 may be a dedicated microprocessor and its architecture is optimized for the operational requirements of digital signal processing, including continuous processing of the signal from the digital comparator 324; and a general purpose processor is not sufficient to continuously process this signal in real time in view of the operational requirements. For example, the digital signal processor 332 as well as the up/down counter 318, digital peak detector 322, and digital comparator 324 may be implemented using resistor-transistor logic (RTL) or combinational logic.

The RTL circuit may be established using resistors and bipolar junction transistors. The combinational logic may perform a boolean operation on the input signals to the digital signal processor 332. It is further contemplated that the digital signal processor 332, up/down counter 318, digital peak detector 322, and digital comparator 324 may be implemented on a Field Programmable Gate Array (FPGA), or on an Application Specific Integrated Circuit (ASIC), for example.

Illustratively, the digital signal processor 332 may provide a search filter for narrowing the range of currents in which the peaks 206 and valleys 210 may be detected. For example, a filter for narrowing the current range may be configured to set the top search level and the bottom search level 334 using the digital interface 326.

The digital signal processor 332 may further provide programmable timing parameters. The timing parameters may include a deglitch timing 336 for eliminating noise portions of the solenoid 302 cycle that are not indicative of electrically powered plunger motion.

The digital signal processor 332 may still further provide other user configurable signal processing filter parameters. For example, the signal processing filter parameters may include a slope curve 338.

The slope curve 338 may be the expected slope before, during, and after the dip 208 of fig. 2. The digital signal processor 332 may compare the slope from the up/down counter 318 before, during, and after the fall 208 to a slope curve 338.

An error may be generated if the slope of the measured current from the up/down counter 318 before, during, and after the drop 208 deviates from the slope curve 338 by more than a slope threshold. The slope threshold may also be provided as a user-configurable parameter using the digital interface 326.

Digital interface 326 may be further coupled to memory 340. For example, memory 340 may include registers or Static Random Access Memory (SRAM).

The memory 340 may store measured parameters of the solenoid 102, such as the magnitude of the drop, the amount of time between the start of supplying current and reaching the peak 206, and the slope before, during, and after the drop 208.

Digital interface 326 may provide previous measurements from solenoid 102 from memory 340 to digital signal processor 332. The digital signal processor 332 may compare previous measurements from the solenoid 102 with current measurements of the solenoid 102 to determine the age of the solenoid 102.

It is contemplated that the memory 340 may further include a threshold value provided to the digital signal processor 332 for determining whether the difference between the previous measurement and the current measurement of the solenoid 102 is large enough to be considered an error. It has been found that comparing the current measurement with the previous measurement can measure the change in the solenoid 102 as the solenoid 102 ages and enable replacement or maintenance of the solenoid 102.

It has been found that detected errors reported by the detection system 300 can provide timely and affordable detection of improper plunger 306 movement, which is highly desirable in many industries, including the manufacturing industry, the healthcare industry, and the automotive industry.

Referring now to FIG. 4, a control flow for detecting solenoid plunger movement using the detection system is shown, the control flow comprising: in block 402, a current supplied to a solenoid is detected with a current sensor; in block 404, converting the current supplied to the solenoid to a digital signal with a counter coupled to a first comparator; in block 406, detecting a peak within the digital signal with a peak detector; in block 408, the peak value is compared to the digital signal with a second comparator coupled to the peak detector; in block 410, a fall from the peak is measured with a second comparator, and a valley is measured; in block 412, an error is generated when the peaks and valleys indicate a smooth current rise of the solenoid; in block 414, receiving, with a signal processor, configurable parameters for processing the digital signal; and in block 416, utilizing the interface to provide configurable parameters to the counter, the second comparator, the signal processor, or a combination thereof.

Thus, it has been found that detection systems provide important and heretofore unknown and unavailable solutions, capabilities and functional aspects. The resulting configuration is simple, economical, uncomplicated, highly versatile, accurate, sensitive, and effective, and can be implemented by adapting known components for ready, efficient, and economical manufacturing, application, and utilization.

Although the detection system has been described in conjunction with a specific best mode, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the included claims. All subject matter set forth herein or shown in the accompanying drawings is to be interpreted in an illustrative and non-limiting sense.

Claims

1. A method of detecting solenoid plunger movement, the method comprising:

detecting a current supplied to the solenoid using a current sensor;

converting the current supplied to the solenoid into a digital signal using a counter;

detecting a peak within the digital signal with a peak detector;

comparing the peak value to the digital signal with a comparator coupled to the peak detector;

measuring a dip from the peak with the comparator and measuring a valley;

generating an error when the peak and the valley indicate a smooth current rise of the solenoid; and

the current to the solenoid is controlled with a second comparator that acts as a component within a current driven regulation loop, wherein the second comparator is coupled to the counter.

2. The method of claim 1, wherein generating the error comprises generating the error based on a difference between the peak and the valley being less than a falling amplitude threshold.

3. The method of claim 1, further comprising determining, with a signal processor coupled to the counter, a difference between a previous measurement from the solenoid and a current measurement of the solenoid.

4. The method of claim 1, wherein detecting the peak comprises detecting a peak from a back electromagnetic force generated by movement of the plunger.

5. A method of detecting solenoid plunger movement, the method comprising:

detecting a current supplied to the solenoid using a current sensor;

converting the current supplied to the solenoid into a digital signal with a counter coupled to a first comparator, the first comparator acting as a component within a current-driven regulation loop, thereby ensuring that a controlled amount of current is supplied to the solenoid;

detecting a peak in the digital signal using a peak detector;

comparing the peak value to the digital signal with a second comparator coupled to the peak detector;

measuring a dip from the peak with the second comparator and measuring a valley;

generating an error when the peak and the valley indicate a smooth current rise of the solenoid;

receiving, with a signal processor, configurable parameters for processing the digital signal; and

an interface is utilized to provide the configurable parameter to the counter, the second comparator, the signal processor, or a combination thereof.

6. The method of claim 5, further comprising:

receiving a start/end threshold from the interface; and

converting the current supplied to the solenoid into the digital signal only between the start/end thresholds with the counter.

7. The method of claim 5, further comprising receiving a top search level and a bottom search level for narrowing a range of the current in which the peak, the dip, and the valley can be identified with the signal processor.

8. The method of claim 5, further comprising receiving, with the signal processor, deglitch pulse timing to eliminate portions of the cycle of the solenoid that are not indicative of electrically powered plunger motion.

9. The method of claim 5, further comprising:

receiving, with the signal processor, a slope curve;

comparing, with the signal processor, slopes before, during, and after the descent to the slope curve; and

the error is generated based on a deviation from the slope curve with the signal processor.

10. A solenoid plunger movement detection system comprising:

a solenoid;

a current sensor coupled to an input of the solenoid, the current sensor detecting a current supplied to the solenoid;

a counter coupled to a first comparator, the counter converting the current supplied to the solenoid to a digital signal, the first comparator acting as a component within a current-driven regulation loop, thereby ensuring that a controlled amount of current is supplied to the solenoid;

a peak detector coupled to the counter, the peak detector detecting a peak within the digital signal; and

a second comparator coupled to the peak detector, the second comparator comparing the peak value with the digital signal and measuring a drop from the peak value and measuring a valley value, and the second comparator generating an error based on the peak value and the valley value indicating a smooth current rise of the solenoid.

11. The system of claim 10, wherein the second comparator includes a falling amplitude threshold and the second comparator generates the error based on a difference between the peak and the valley being less than the falling amplitude threshold.

12. The system of claim 10, further comprising a signal processor that determines a difference between a previous measurement from the solenoid and a current measurement of the solenoid.

13. The system of claim 10, wherein the peak detector detects a peak value from the back electromagnetic force generated by the movement of the plunger.

14. The system of claim 10, further comprising:

a signal processor coupled to the second comparator, the signal processor receiving configurable parameters for processing the digital signal; and

an interface that provides the configurable parameter to the counter, the second comparator, the signal processor, or a combination thereof.

15. The system of claim 14, wherein the counter receives a start/end threshold from the interface and converts the current supplied to the solenoid to the digital signal only between the start/end thresholds.

16. The system of claim 14, wherein the signal processor receives a top search level and a bottom search level that narrow the range of currents in which the peak, the dip, and the valley can be identified.

17. The system of claim 14, wherein the signal processor receives deglitch pulse timing to eliminate portions of the solenoid cycle that do not indicate electrically powered plunger motion.

18. The system of claim 14, wherein the signal processor receives a slope curve, the signal processor compares slopes before, during, and after the drop to the slope curve, and the signal processor generates the error based on a deviation from the slope curve.