Insulation inspection system with voltage and current balancing circuit

Abstract

An insulation inspection system having a voltage and current balancing circuit is provided. An insulation inspection system includes: a set of input terminals; a brush; a circuit connected to the set of input terminals, the brush, and the part to be inspected, wherein the circuit includes at least one pair of resistor and capacitor; and a control module configured to detect when there is a short circuit between the conductive element of the part and the one or more conductive bristles due to the absence of insulating material on the part and thus the one or more conductive bristles of the brush contacting the conductive element of the part.

Description

[0001] Introduction

[0002] The information provided in this section is for the purpose of presenting the context of the present disclosure generally. To the extent that the work of the presently named inventors is described in this section and aspects of this description that may not otherwise be eligible as prior art at the time of filing are neither expressly nor implicitly admitted as prior art against the present disclosure. Technical Field

[0003] The present disclosure relates to a continuity testing system, and more particularly to an insulation inspection system for inspecting stator windings and other electrical components. Background Art

[0004] Electric and hybrid vehicles include traction motors for propulsion purposes. Each traction motor includes a stator and a rotor, which have corresponding windings and conductive bars. The windings and / or conductive bars may be insulated (e.g., having an external insulation coating). During manufacturing (including the formation and assembly of parts and components), the insulation coating may not be formed correctly or may be scratched, scraped, rubbed, etc. This may result in a lack of and / or removal of part of the insulation coating, thereby exposing the conductive elements. Such exposure may cause short circuits, affect motor performance, and / or reduce motor life. Summary of the Invention

[0005] An insulation inspection system is disclosed and includes: a set of input terminals; a brush; a circuit connected to the set of input terminals, the brush, and the part to be inspected, wherein the circuit includes at least a pair of resistors and capacitors; and a control module configured to detect when there is a short circuit between the conductive elements of the part and one or more conductive bristles of the brush due to a lack of insulation material on the part and thus contact of one or more conductive bristles of the brush with the conductive elements of the part.

[0006] In other features, the set of input terminals includes a positive terminal and a negative terminal. The capacitor and a first resistor of the pair of resistors are connected in series between the positive terminal and the negative terminal.

[0007] In other features, the set of terminals includes a common terminal separate from the positive terminal and the negative terminal. A second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0008] In other features, the set of terminals includes a positive terminal, a negative terminal, and a common terminal. The circuit is implemented as a voltage and current balance circuit and includes the pair of resistors and the capacitor connected in series between the positive terminal and the common terminal. The first resistor of the pair of resistors and the capacitor are connected in series between the positive terminal and the negative terminal. The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0009] Among other features, the capacitor is connected across the power supply and between the positive and negative terminals.

[0010] Among other features, the first resistor includes i) a first end connected to the first end of the capacitor, and ii) a second end connected to the first of the set of input terminals and to the brush. The second resistor includes i) a first end connected to the second of the set of input terminals, to the second end of the capacitor, and to the part, and ii) a second end connected to the third of the set of input terminals.

[0011] Among other features, the first end of the capacitor is connected to the positive terminal of the power supply. The second end of the capacitor is connected to the negative terminal of the power supply.

[0012] Among other features, the lead is connected between: i) the second of the set of input terminals, the first end of the second resistor, and the second end of the capacitor, and ii) one or more three-phase contacts of the part.

[0013] Among other features, the insulation inspection system further includes an analog-to-digital converter connected to the circuit and configured to convert an analog signal output from the circuit into a digital signal. The control module is configured to detect, based on the digital signal, when there is a short circuit between the conductive element of the part and one or more conductive bristles.

[0014] Among other features, the control module is configured to generate at least one of a message or an alert when a short circuit is detected between the conductive element of the part and one or more conductive bristles.

[0015] Among other features, an insulation inspection method is disclosed and includes: connecting a lead to the part to be inspected; moving a brush across a portion of the part or moving the part relative to the brush; detecting, via a circuit, a voltage drop across a pair of input terminals, where the circuit is connected to the pair of input terminals, the brush, and the part, and where the circuit includes at least one of a pair of resistors and a capacitor; and determining whether the voltage drop indicates when there is a short circuit between the conductive element of the part and one or more conductive bristles of the brush due to a lack of insulating material on the part and thus contact of one or more conductive bristles of the brush with the conductive element of the part.

[0016] Among other features, the set of input terminals includes a positive terminal and a negative terminal. The capacitor and the first resistor of the pair of resistors are connected in series between the positive and negative terminals.

[0017] Among other features, the set of terminals includes a common terminal separate from the positive and negative terminals. The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0018] Among other features, the set of terminals includes a positive terminal, a negative terminal, and a common terminal. The circuit is implemented as a voltage and current balancing circuit and includes the pair of resistor and capacitor connected in series between the positive terminal and the common terminal. The first resistor and the capacitor of the pair of resistors are connected in series between the positive terminal and the negative terminal. The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0019] Among other features, the capacitor is connected across the power supply and between the positive terminal and the negative terminal.

[0020] Among other features, the pair of resistors includes a first resistor and a second resistor. The first resistor includes i) a first end connected to the first end of the capacitor, and ii) a second end connected to the first of the set of input terminals and to the brush. The second resistor includes i) a first end connected to the second of the set of input terminals, to the second end of the capacitor, and to the part, and ii) a second end connected to the third of the set of input terminals.

[0021] Among other features, the first end of the capacitor is connected to the positive terminal of the power supply. The second end of the capacitor is connected to the negative terminal of the power supply.

[0022] Among other features, leads are connected between: i) the second of the set of input terminals, the first end of the second resistor, and the second end of the capacitor, and ii) one or more three-phase contacts of the part.

[0023] Among other features, the insulation inspection method further includes: converting an analog signal output from the circuit into a digital signal via an analog-to-digital converter, where the analog-to-digital converter is connected to the circuit; and based on the digital signal, detecting when there is a short circuit between the conductive element of the part and one or more conductive bristles.

[0024] Among other features, the insulation inspection method further includes generating at least one of a message or an alarm when a short circuit between the conductive element of the part and one or more conductive bristles is detected.

[0025] The present invention also includes the following solutions:

[0026] Solution 1. An insulation inspection system, comprising:

[0027] A set of input terminals;

[0028] A brush;

[0029] A circuit connected to the set of input terminals, the brush, and the part to be inspected, where the circuit includes at least one of a pair of resistors and a capacitor; and

[0030] A control module configured to detect when a short circuit exists between the conductive elements of the part and the one or more conductive bristles of the brush due to a lack of insulating material on the part and thus contact of one or more conductive bristles of the brush with the conductive elements of the part.

[0031] Solution 2. The insulation inspection system according to Solution 1, wherein:

[0032] The set of input terminals includes a positive terminal and a negative terminal; and

[0033] The capacitor and the first resistor of the pair of resistors are connected in series between the positive terminal and the negative terminal.

[0034] Solution 3. The insulation inspection system according to Solution 2, wherein:

[0035] The set of terminals includes a common terminal separate from the positive terminal and the negative terminal; and

[0036] The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0037] Solution 4. The insulation inspection system according to Solution 1, wherein:

[0038] The set of terminals includes a positive terminal, a negative terminal, and a common terminal;

[0039] The circuit is implemented as a voltage and current balance circuit and includes the pair of resistors and the capacitor connected in series between the positive terminal and the common terminal;

[0040] The first resistor of the pair of resistors and the capacitor are connected in series between the positive terminal and the negative terminal; and

[0041] The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0042] Solution 5. The insulation inspection system according to Solution 4, wherein the capacitor is connected across the power supply and between the positive terminal and the negative terminal.

[0043] Solution 6. The insulation inspection system according to Solution 5, wherein:

[0044] The first resistor includes i) a first end connected to the first end of the capacitor, and ii) a second end connected to the first of the set of input terminals and connected to the brush; and

[0045] The second resistor includes i) a first end connected to the second of the set of input terminals, connected to the second end of the capacitor, and connected to the component, and ii) a second end connected to the third of the set of input terminals.

[0046] Aspect 7. The insulation inspection system according to Aspect 6, wherein:

[0047] The first end of the capacitor is connected to the positive terminal of the power supply; and

[0048] The second end of the capacitor is connected to the negative terminal of the power supply.

[0049] Aspect 8. The insulation inspection system according to Aspect 6, wherein leads are connected between: i) the second of the set of input terminals, the first end of the second resistor, and the second end of the capacitor, and ii) one or more three-phase contacts of the component.

[0050] Aspect 9. The insulation inspection system according to Aspect 1, further comprising an analog-to-digital converter connected to the circuit and configured to convert an analog signal output from the circuit into a digital signal,

[0051] wherein the control module is configured to detect when there is a short circuit between the conductive elements of the component and the one or more conductive bristles based on the digital signal.

[0052] Aspect 10. The insulation inspection system according to Aspect 1, wherein the control module is configured to generate at least one of a message or an alarm when a short circuit between the conductive elements of the component and the one or more conductive bristles is detected.

[0053] Aspect 11. An insulation inspection method, comprising:

[0054] Connecting leads to a component to be inspected;

[0055] Moving a brush across a portion of the component or moving the component relative to the brush;

[0056] Detecting a voltage drop across a pair of input terminals via a circuit, wherein the circuit is connected to the pair of input terminals, the brush, and the component, and wherein the circuit includes at least one of a pair of resistors and a capacitor; and

[0057] Determining whether the voltage drop indicates when there is a short circuit between the conductive elements of the component and one or more conductive bristles of the brush due to a lack of insulating material on the component and thus contact of one or more conductive bristles of the brush with the conductive elements of the component.

[0058] Solution 12. The insulation inspection method according to Solution 11, wherein:

[0059] The set of input terminals includes a positive terminal and a negative terminal; and

[0060] The capacitor and the first resistor of the pair of resistors are connected in series between the positive terminal and the negative terminal.

[0061] Solution 13. The insulation inspection method according to Solution 12, wherein:

[0062] The set of terminals includes a common terminal separated from the positive terminal and the negative terminal; and

[0063] The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0064] Solution 14. The insulation inspection method according to Solution 11, wherein:

[0065] The set of terminals includes a positive terminal, a negative terminal, and a common terminal;

[0066] The circuit is implemented as a voltage and current balance circuit and includes the pair of resistors and the capacitor connected in series between the positive terminal and the common terminal;

[0067] The first resistor of the pair of resistors and the capacitor are connected in series between the positive terminal and the negative terminal; and

[0068] The second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

[0069] Solution 15. The insulation inspection method according to Solution 14, wherein the capacitor is connected across the power supply and between the positive terminal and the negative terminal.

[0070] Solution 16. The insulation inspection method according to Solution 15, wherein:

[0071] The pair of resistors includes a first resistor and a second resistor;

[0072] The first resistor includes i) a first end connected to the first end of the capacitor, and ii) a second end connected to the first of the set of input terminals and connected to the brush; and

[0073] The second resistor includes i) a first end connected to the second of the set of input terminals, connected to the second end of the capacitor, and connected to the part, and ii) a second end connected to the third of the set of input terminals.

[0074] Solution 17. The insulation inspection method according to Solution 16, wherein:

[0075] The first end of the capacitor is connected to the positive terminal of the power supply; and

[0076] The second end of the capacitor is connected to the negative terminal of the power supply.

[0077] Solution 18. The insulation inspection method according to Solution 16, wherein the lead is connected between: i) the second one of the set of input terminals, the first end of the second resistor, and the second end of the capacitor, and ii) one or more three-phase contacts of the part.

[0078] Solution 19. The insulation inspection method according to Solution 11, further comprising:

[0079] Converting an analog signal output from the circuit into a digital signal via an analog-to-digital converter, wherein the analog-to-digital converter is connected to the circuit; and

[0080] Based on the digital signal, detecting when there is a short circuit between the conductive element of the part and the one or more conductive bristles.

[0081] Solution 20. The insulation inspection method according to Solution 11, further comprising generating at least one of a message or an alarm when a short circuit between the conductive element of the part and the one or more conductive bristles is detected.

[0082] Based on the detailed description, the claims, and the drawings, additional fields of applicability of the present disclosure will become apparent. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The present disclosure will be more fully understood from the detailed description and the accompanying drawings, wherein:

[0084] Figure 1 is a bottom view of a part of a stator, which illustrates an example defect in an insulating coating;

[0085] Figure 2 is a schematic view of an example insulation inspection system for inspecting a stator and including a voltage and current balance circuit according to the present disclosure;

[0086] Figure 3 is of an individual hairpin for inspecting a stator according to the present disclosure Figure 2 of a schematic view of an insulation inspection system; and

[0087] Figure 4 illustrates an example insulation inspection method for detecting, marking, identifying, and reporting defects according to the present disclosure.

[0088] In the drawings, reference numerals may be reused to identify similar and / or identical elements. Detailed Description

[0089] During manufacturing, the electric machine can be inspected to detect defects such as defects in the insulation coating of the electrical components of the stator. The insulation coating can be visually inspected. This can include a quality control technician visually inspecting for defects in the insulation coating of the stator using a magnifying glass. Such inspections are labor-intensive and are limited by the technician. A continuity tester can be used, which applies a voltage to the stator and detects when a short circuit exists. When there is a lack of insulating material where the tester contacts the stator, current flows between the stator and the continuity tester.

[0090] The continuity tester can include a brush having conductive bristles. The bristles can move across and brush various parts of the stator to detect short circuit locations (i.e., defect locations) where there is a lack of insulating material. The reverse can also occur where the component (or stator) moves past the bristles and the brush is stationary. A circuit is used to monitor changes in voltage at the brush. When a short circuit occurs, the voltage drops significantly. There are large voltage and current fluctuations between when there is no short circuit and when there is indeed a short circuit.

[0091] If not managed properly, over time, the large voltage and current fluctuations in the circuit can be harmful to the component. As a result, the component can degrade over time, and this degradation can negatively impact the operation of the circuit. For example, an A / D converter may have specific voltage and current limits for operation based on what is used. If there is any resulting drift in circuit components such as resistors or other circuit components, this can lead to voltage response behavior that can cause problems with voltage threshold settings and inappropriately detecting short circuits. Degradation of circuit components can cause voltage drift, which can cause subsequent defects to go undetected. Therefore, drift requires circuit adjustment and periodic recalibration (including adjustment of the threshold). A defect can be detected when the voltage drops below the threshold. As an example, the threshold can be set to 5 volts (V), which is significantly lower than the nominal voltage and / or the normally expected voltage (e.g., 24V). The threshold can be set to be less than or equal to 20% of the nominal voltage.

[0092] Drift can also lead to unsafe current levels. If circuit components degrade over time and there is a resulting change in the expected current of the circuit, this can lead to current levels in the circuit that may exceed the threshold for perceived and / or actual bodily harm. Additionally, current levels above the expected level can also be harmful to parts and the brush, even when human exposure is mitigated.

[0093] The examples described herein include an insulation inspection system having a voltage and current balance circuit, as shown in Figures 2 - 3 . The voltage and current balance circuit provides a balanced voltage response at a nominal low current that is detected via the bristles of a continuity test brush used to detect a defect (or short). The voltage and current balance provides stability, improves the lifespan of circuit components, and provides improved functionality, thereby allowing the insulation inspection system to be used in a variety of applications while being safe for human touch. In addition to the hardware described, the insulation inspection system also includes an algorithm for marking defective parts. The algorithm improves sensitivity to better detect defects.

[0094] The voltage and current balance circuit improves the flexibility of safety by incorporating capacitors for voltage distribution and appropriately sized resistors R1 and R2. Resistors R1 and R2 are selected to generate a low current response. The capacitors and resistors are connected across the common, negative, and positive terminals of an analog-to-digital (A / D) converter. The values of resistors R1 and R2 are selected to generate a low current response during and / or at all operating points throughout the operation of the voltage and current balance circuit. The low current response makes the test setup safe for the operator. When there is no electrical short, the capacitor creates an open-circuit condition. When a short is detected using a brush (e.g., a brush with carbon bristles), the voltage at the positive terminal of the capacitor drops, which causes a voltage drop across resistors R1 and R2 such that the voltage at each positive and negative terminal of the A / D converter remains within a predetermined voltage range (e.g., ±13V) relative to the voltage on the A / D common terminal.

[0095] Resistors R1 and R2 are selected such that the current throughout the voltage and current balance circuit remains below a predetermined current (e.g., less than or equal to 25 mA, which is not perceptible to human contact) when there is a short. From the perspective of the incoming analog voltage signal, this will keep the positive terminal of the A / D converter at the nominal operating voltage (e.g., 24V) and the negative terminal of the A / D converter at 0V when there is no short. When a break in the insulation occurs, i.e., a short in the connection from the brush to the phase lead, the following changes occur in the voltage and current balance circuit. The positive A / D terminal is forced towards 0V. It is noted that due to the intermittent contact between the brush bristles, the positive A / D terminal may not fully reach 0V, but in the case of a stable short, the positive A / D terminal is forced to 0V. A defect is detected when the positive A / D terminal drops to a predetermined threshold (e.g., 5V) or below a predetermined threshold (e.g., 5V), or is lower compared to a reference or no-short nominal voltage (e.g., 24V).

[0096] Since the negative A / D terminal is maintained at 0 V, there is a 0 V difference between the positive A / D terminal and the negative A / D terminal, and thus the common A / D terminal is also at 0 V. Accordingly, the resistor R2 connected across the negative A / D terminal and the common A / D terminal experiences a 0 V drop (no current flow).

[0097] When a defect is detected, the capacitor will have charge available to discharge as needed, rather than directly connecting a power supply that supplies a nominal voltage to a short circuit (or defect). This allows for a constant voltage drop across the capacitor to be maintained while minimizing the current flow in any branch of the voltage and current balancing circuit when the corresponding brush makes intermittent contact with the defect. This is done by maintaining a resistor-capacitor (RC) time constant long enough such that the discharge of the capacitor does not cause large fluctuations in the voltage drop across the capacitor during the duration of the intermittent contact between the brush and the defective area. As an example, the time constant can be 24 seconds. This results in resistor R1 being connected between i) the capacitor and ii) the positive A / D terminal and the brush, such that it primarily experiences a voltage drop in the event of a short circuit condition.

[0098] To ensure that the current in the circuit does not exceed what a human body would be able to sense, resistor R1 is chosen such that the current will not exceed a threshold (e.g., 1 milliampere (mA)) when a short circuit exists. This voltage and current balance at all operating points allows the entire voltage and current balancing circuit to be safe for human touch, as well as not introducing current or voltage levels that would damage the brush bristles or the part being inspected. The current and voltage levels are kept below a predetermined threshold to prevent, for example, arcing.

[0099] When a short circuit exists, the capacitor can discharge at an appropriate rate to allow for a quick and stable measurement. Current flows through the resistor and provides an analog voltage measurement to the A / D converter. Once the brush is removed from the defect and the short circuit no longer exists, the capacitor is charged until it returns to an open circuit state.

[0100] The voltage and current balancing circuit prevents circuit component degradation by preventing large voltage and current fluctuations across circuit components in the case of a short circuit. The values of the capacitor and resistor are selected to improve circuit performance and prevent circuit component degradation due to parasitic voltages across the resistor. These values are selected to prevent drift in the circuit component values. This prevents a larger than expected voltage drop across the brush bristles and arcing.

[0101] Figure 1 A portion 100 of a stator is shown. The stator includes pairs of welded wires coated with an insulating material. Portion 100 includes a defect 102 where a portion of the insulating coating 104 is missing and the conductive material 106 of the wire is exposed. In Figure 1In [description], the bottom (or welding end) of the stator is shown. The stator includes a laminated stack (or body) 110 having a bottom surface 112 and a plurality of ear portions ( Figure 1 In [description], one ear portion 114 is shown). As an example, the insulating coating 104 can be epoxy resin.

[0102] Figure 2 An insulation inspection system 200 for inspecting the stator 202 is shown. The insulation inspection system 200 includes a human-machine interface (HMI) 204 and a voltage and current balance circuit 206 connected to a power supply 208. The HMI 204 can include a control module 210, an A / D converter 212, a memory 214, a transceiver 216, a display 218, and an auditory device 220. The display 218 includes an LED 222 and / or other visual displays and / or indicator elements. The control module 210 receives digital voltage data from the A / D converter 212, which receives an analog input signal from the voltage and current balance circuit 206. When the voltage of the analog output signal (or the corresponding digital signal) across the positive terminal 223 and the negative terminal 226 of the A / D converter 212 drops below a threshold value (e.g., 5V or 20% of the nominal or normal expected voltage (e.g., 24V)), the control module 210 detects a defect. The normal expected voltage without detecting a defect can be 24V. The control module 210 can indicate the detection of the defect via the display 218 and the auditory device 220. The detection of the defect, the change (or drop) in voltage, the timing of the detection, and / or other relevant information can be stored in the memory 214. As an example, the detection of the defect can be stored together with the approximate position of the defect relative to one or more reference points on the stator 202.

[0103] The display 218 provides visual assistance for indicating the detection of the defect. This also provides an indication of when the defect is detected. When a defect is detected, the auditory device 220 can provide a loud sound, such as a loud alarm signal. The auditory device 220 can include, for example, a speaker. The control module 210 can report the detected defect and the corresponding information stored in the memory 214 to one or more network devices located away from the HMI 204 via the transceiver 216.

[0104] The voltage and current balance circuit 206 includes resistors R1, R2, and capacitor C. Resistor R1 has: i) a first end that is connected to the first (or positive) terminal of the A / D converter 212 and to the brush 228; and ii) a second end that is connected to the first end of the capacitor C and to the positive terminal of the power supply 208. Resistor R2 includes: i) a first end that is connected to the second (or negative) input terminal 226 of the A / D converter 212, the second end of the capacitor, one or more three-phase contacts 224, and the negative terminal of the power supply 208; and ii) a second end that is connected to the third (or common) terminal COM of the A / D converter 212. The common terminal COM is separated from either of the terminals 223, 226 and is not connected to either of the terminals 223, 226. A lead 225 is connected between i) the negative terminal 226, the first end of resistor R2, and the second end of capacitor C and ii) one or more three-phase contacts 224. The first end of capacitor C is connected to the positive terminal of the power supply 208. The second end of capacitor C is connected to the negative terminal of the power supply 208.

[0105] Resistors R1, R2, and capacitor C are connected in series between terminal 223 and the common terminal COM. In the example shown, capacitor C is connected between resistors R1 and R2. In one embodiment, resistors R1 and R2 are directly connected to terminals 223, 226 and directly connected to capacitor C. Resistor R1 may be directly connected to brush 228. Resistor R2 may be directly connected to the stator 202.

[0106] As an example, resistor R1 may be 20 - 30 kiloohms (kΩ), resistor R2 may be 400 - 500 kΩ, and the capacitor may be 500 - 1500 microfarads (μF). In one embodiment, R1 is 24 kΩ, R2 is 470 kΩ, and C is 1000 μF. The resistance of the resistors and the capacitance of the capacitor are selected to provide the RC time constant referred to herein. In one embodiment, the resistance of resistors R1, R2 is selected to limit the amount of current flowing through the stator 202, the voltage and current balance circuit 206, and the brush 228. The resistance of resistors R1 and R2 and the capacitance of capacitor C are selected, i) to prevent arcing and sparking at the bristles 230 when a defect (short circuit) occurs, and ii) for proper current balance in the circuit during all test conditions to maintain safety for human touch (less than 1 mA). For example, the resistance of resistors R1 and R2 may be selected to prevent the current through the circuit 206, brush 228, and stator 202 from exceeding a predetermined threshold.

[0107] Select the resistance value to limit the current during all aspects of operation and balance the voltage load permitted across the channels of the A / D converter 212, such as the voltage loads associated with terminals 223, 226. In one embodiment, and regardless of whether a defect (a short circuit occurs) or no defect (no short circuit) exists, the current is maintained between 25 microamps (uA) and 1 mA due to i) the placement and selected values of resistors R1 and R2 and capacitor C in the voltage and current balancing circuit 206 associated with the power supply 208 (e.g., a 24 VDC power supply), and ii) the A / D voltage channel limitations between different channels with respect to the A / D common terminal COM. The resistance of R1 and R2 can be changed based on the A / D behavior limitations to maintain the described current behavior. As an example, the channel limitations can be such that the A / D channels of the A / D converter are within ±10 - 13 V of the A / D common terminal COM. In one embodiment, the channel limitations are such that the A / D channels are within ±10.2 V of the A / D common terminal COM.

[0108] Select the capacitance rating of capacitor C to provide a long enough RC time constant in combination with the value of R1 chosen for current level reasons. This is done to provide a stable nominal voltage (e.g., a stable 24 V) to the voltage and current balancing circuit 208 during the time window spent determining whether a short circuit has occurred. The R1*C value can provide a time constant of approximately 24 seconds. This provides a long enough time constant that does not need to be further increased with larger C values, although the time constant can be further increased. If the time constant is too small, then the charging and discharging behavior of capacitor C will affect the circuit operation because when a defect occurs, the nominal voltage will no longer remain stable at 24 V. Since the voltage response will become intricate due to the behavior of capacitor C, this can make it challenging to assign a specific defect detection threshold.

[0109] The capacitance of capacitor C affects the rate of change of current flowing through stator 202, voltage and current balance circuit 206, and brush 228. Capacitor C is included as a protection device for brush 228 and bristles 230 and prevents current surges from the power supply 208 to the short - circuit location. When there is no short - circuit, capacitor C is charged. When a short - circuit exists, capacitor C discharges. Due to the use of the RC time constant, capacitor C does not discharge completely. This helps to limit the current in the circuit during a short - circuit event. After discharging, power supply 208 re - charges capacitor C. Typically, if the bristles are moving, the short - circuit lasts for a short period of time. In the absence of capacitor C, resistors R1 and R2 may deteriorate due to short - circuits and current surges through resistors R1 and R2. The capacitance and resistance values can also be selected based on the application used to provide a low current draw for safe operator use. For example, the capacitance of capacitor C and the resistance of resistors R1, R2 can be selected to accommodate different electric brush head designs for defect detection. In one embodiment, the brush is designed to have a low impedance compared to the circuit components. The insulation inspection system 200 is capable of accommodating brushes with a variety of different designs.

[0110] HMI 204 and / or A / D converter 212 detect the analog voltage across terminals 223, 226. Filtering of the A / D signal is done through data sampling to remove noise associated with the electrical behavior of the bristles of the brush. The voltage from power supply 208 is provided across capacitor C, which, in combination with resistor R1, provides a stable voltage to brush 228, and one of the three - phase contacts 224 of stator 202 is connected to lead 225. When one or more conductive bristles 230 come into contact with the exposed conductive elements of stator 202, current flows from one of the three - phase contacts 224 through stator 202 and to one or more bristles 230 in contact with the exposed conductive elements. The three - phase contacts 224 include three contacts: one for each phase of the three - phase stator 202. In one embodiment, the three - phase contacts 224 are connected to each other such that current can flow through any phase of stator 202. In another embodiment, voltage is provided to one of the three - phase contacts 224 of stator 202, and the brush is connected to lead 225.

[0111] The insulation inspection system 200 can be used to inspect the crown end 240, the welded end 242, and / or other parts of stator 202 as shown. The insulation inspection system 200 can also be used to inspect individual electrical components and / or elements, examples of which are shown in Figure 3 The crown end 240 extends upward from the laminate stack 244. The welded end extends downward from the laminate stack 244. The bristles 230 can move along different components of stator 202 to detect the location of missing insulation material.

[0112] The insulation inspection system 200 includes software and hardware with an adjustable A / D voltage threshold for marking defects. As an example, the threshold for marking defects can be set to 5V, but it can be different for different applications. The control module 210 implements a detection algorithm that detects when the voltage across terminals 223, 226 drops below one of the A / D voltage thresholds and generates a visual and / or audible signal to mark the detected defect.

[0113] The above voltage and current balancing circuit minimizes the current level at all operating points, regardless of the presence of a short circuit. The inclusion, selection, and arrangement of the resistors and capacitors as described prevent large voltage and current fluctuations and thus prevent component degradation over time. This maintains the current level below the threshold associated with perceived and / or actual harm.

[0114] Figure 3 An insulation inspection system 200 for inspecting the individual hairpins 300 of a stator is shown. The insulation inspection system 200 includes an HMI 204 and a voltage and current balancing circuit 206 connected to a power supply 208. The HMI 204 can include a control module 210, an A / D converter 212, a memory 214, a transceiver 216, a display 218, and an audible device 220. The display 218 can include an LED 222 and / or other visual displays and / or indicator elements. The voltage and current balancing circuit 206 includes resistors R1, R2, and a capacitor C. The A / D converter 212 includes input terminals 223, 226.

[0115] Resistor R1 has i) a first end that is connected to the first (or positive) terminal of the A / D converter 212 and a brush 228, and ii) a second end that is connected to the first end of the capacitor C and the positive terminal of the power supply 208. Resistor R2 includes i) a first end that is connected to the second (or negative) input terminal 226 of the A / D converter 212, the second end of the capacitor, one end of the hairpin 300, and the negative terminal of the power supply 208, and ii) a second end that is connected to the third (or common) terminal COM of the A / D converter 212. The common terminal COM is separated from either of the terminals 223, 226 and is not connected to either of the terminals 223, 226. A lead 225 is connected between: i) the negative terminal 226, the first end of resistor R2, and the second end of the capacitor C; and ii) one or more 3-phase contacts 224. The first end of the capacitor C is connected to the positive terminal of the power supply 208. The second end of the capacitor C is connected to the negative terminal of the power supply 208.

[0116] Resistors R1, R2, and capacitor C are connected in series between terminal 223 and common terminal COM. In the illustrated example, capacitor C is connected between resistors R1 and R2. In one embodiment, resistors R1 and R2 are directly connected to terminals 223, 226 and directly connected to capacitor C. Resistor R1 may be directly connected to brush 228. Resistor R2 may be directly connected to hairpin 300.

[0117] Hairpin 300 may include a wire coated with a dielectric material (such as epoxy resin). The bristles 230 of brush 228 may move along hairpin 300 to determine whether a portion of the wire is exposed through the dielectric coating or hairpin 300 may move relative to brush 228.

[0118] Figure 4 An insulation inspection method for detecting, marking, identifying, and reporting defects is illustrated. The insulation inspection method implements a defect detection analysis algorithm including the following operations. These operations may be performed iteratively. The operations shown in solid-line boxes may be performed by Figures 2 - 3 insulation inspection system 200.

[0119] At 400, lead 225 is connected to a part to be inspected, such as the stator of a motor, a hairpin, or other electrical component or element. For example, lead 225 may be connected to one or more 3-phase contacts of the stator.

[0120] At 402, control module 210 begins to monitor the voltages at input terminals 223, 226 and thus monitors the voltage at bristles 230 of brush 228.

[0121] At 404, brush 228 moves over the insulated section of the part to be inspected. This includes brushing bristles 230 over the insulated section such that one or more bristles come into contact with any uninsulated (exposed) conductive material of the part. The exposed conductive material is at the voltage applied to the part by power supply 208. When one or more bristles 230 contact the exposed portion of the part, a short circuit occurs and control module 210 detects a voltage drop. The short circuit produces a sharp voltage drop from the nominal (or normally expected) level to below a threshold level. The bristles maintain contact with the part while moving relative to the part.

[0122] At 406, control module 210 determines whether a defect has been detected. If a defect has been detected, operation 408 is performed, otherwise the method may end. A defect is detected when there is a short circuit between one or more bristles 230 and the exposed conductive elements of the part. When the part is a stator, the short circuit may exist between one or more bristles 230 and the exposed wires of the stator and thus between one or more bristles 230 and one or more 3-phase contacts of the stator.

[0123] At 408, the control module 210 records information about the defect and visually and / or auditorily indicates that a defect has been detected via one or more indicators such as the display 218, the LED 222, and / or the auditory device 220. In one embodiment, a message is displayed via the display 218. The message may include the recorded information. In another embodiment, the message is sent from the HMI 204 to another network device via the transceiver 216. This may occur at 418. The recorded information and the message may include when the defect was detected, the voltage drop rate across the terminals 223, 226, how often the defect was detected, where the defect is located, etc. Depending on the size of the defect and the speed of movement of the brush relative to the part being inspected, the defect may be detected within a short period of time. The location of the defect may be indicated relative to one or more reference points on the part being inspected. In one embodiment, the technician records the location of the detected defect after and / or when seeing and / or hearing the message that a defect has been detected. As an example, a ring may be attached to the welded end of the stator being inspected and have a timing index, and / or the laminated stack of the stator may have a reference point. The index and / or the reference point may be used to determine the location of the detected defect. In one embodiment, the control module 210 marks the defect by lighting a red LED or displaying a red icon. In another embodiment, the control module 210 marks the defect by activating an auditory defect alarm signal.

[0124] At 410, the detected defect may be marked. As an example, the technician may physically mark the defect using a marker. If the brush 228 and / or the bristles impede marking the defect, operation 410 may be performed after operation 412.

[0125] At 412, the brush 228 is removed from the part. At 414, the voltage of the voltage and current balancing circuit 206 returns to the nominal level.

[0126] At 416, the control module 210 stops indicating that a defect has been detected and returns one or more indicators to the normal state. For example, the auditory device 220 that may be providing an auditory message (or alarm) is turned off. The lit LED turns green or is turned off. The displayed red icon is replaced by a green icon or is no longer displayed.

[0127] At 418, the control module 210 may report the defect area where the defect is located and / or other relevant information (such as any of the above information) on the display 218 via the auditory device 220, and / or report it to a network device located away from the HMI 204 via the transceiver 216. This may include an indication of the location of the defect on the part, the time when the defect was detected, and / or other information indicating the location of the defect.

[0128] At 420, the control module can determine whether there are more parts to be inspected. If so, operation 402 can be performed; otherwise, the method can end.

[0129] The foregoing description is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses. The broad teachings of the present disclosure can be implemented in a variety of forms. Thus, while the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited since other modifications will become apparent after study of the drawings, specification, and following claims. It should be understood that one or more steps within a method can be executed in a different order (or concurrently) without altering the principles of the present disclosure. Further, although each embodiment is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure can be implemented in and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the arrangement of one or more embodiments with each other is still within the scope of the present disclosure.

[0130] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "immediately adjacent," "on," "above," "below," and "disposed." Unless explicitly described as "direct," when describing the relationship between a first and a second element in the foregoing disclosure, the relationship can be a direct relationship in which no other intervening element exists between the first and the second elements, but can also be an indirect relationship in which one or more intervening elements (either spatially or functionally) exist between the first and the second elements. As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C) using a non-exclusive logical "or," and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0131] In the various figures, the direction of the arrows—as indicated by the arrowheads—generally indicates the information flow (such as data or instructions) of interest for that illustration. For example, when element A and element B exchange various information, but the information transmitted from element A to element B is relevant to that illustration, the arrow can point from element A to element B. This one-way arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B can send a request for that information or receive an acknowledgement from element A.

[0132] In this application, including the following definitions, the term "module" or the term "controller" may be replaced by the term "circuit". The term "module" may refer to, be part of, or include the following: an application specific integrated circuit (ASIC); digital, analog, or mixed analog / digital discrete circuits; digital, analog, or mixed analog / digital integrated circuits; combinational logic circuits; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or grouped) that executes code; a memory circuit (shared, dedicated, or grouped) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

[0133] A module may include one or more interface circuits. In some examples, the interface circuit may include a wired or wireless interface connected to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules connected via the interface circuit. For example, multiple modules may allow load balancing. In additional examples, a server (also referred to as remote or cloud) module may implement some functionality on behalf of a client module.

[0134] As used above, the term "code" may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects.The term "shared processor circuit" encompasses a single processor circuit that executes some or all of the code from multiple modules. The term "grouped processor circuit" encompasses a processor circuit that, in combination with additional processor circuits, executes some or all of the code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on separate die, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term "shared memory circuit" encompasses a single memory circuit that stores some or all of the code from multiple modules. The term "grouped memory circuit" encompasses a memory circuit that, in combination with additional memory, stores some or all of the code from one or more modules.

[0135] The term "memory circuit" is a subset of the term "computer-readable medium". As used herein, the term "computer-readable medium" does not cover transitory electrical or electromagnetic signals propagated through a medium (such as on a carrier wave); thus, the term "computer-readable medium" can be considered tangible and non-transitory. Non-limiting examples of non-transitory tangible computer-readable media are non-volatile memory circuits (such as flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital magnetic tape or hard disk drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0136] The devices and methods described in this application can be implemented in part or in whole by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. The functional blocks, flowchart components, and other elements described above serve as software specifications that can be transformed into a computer program through the routine work of a skilled technician or programmer.

[0137] A computer program includes processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. A computer program may also include or rely on stored data. A computer program can cover a basic input / output system (BIOS) that interacts with the hardware of a special-purpose computer, device drivers that interact with specific devices of a special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0138] A computer program can include: (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated by a compiler from source code, (iv) source code for execution by an interpreter, (v) source code for just-in-time compilation and execution, etc. By way of example only, the source code can be written using the syntax of languages including: C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Fortran, Perl, Pascal, Curl, OCaml, HTML5 (Fifth Edition of Hypertext Markup Language), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Visual Lua, MATLAB, SIMULINK and

Claims

1. An insulation inspection system, comprising: A set of input terminals; A brush; A circuit connected to the set of input terminals, the brush, and the part to be inspected, wherein the circuit includes at least one of a pair of resistors and a capacitor; And A control module configured to detect when a short circuit exists between the conductive elements of the part and one or more conductive bristles of the brush due to a lack of insulating material on the part and thus contact of one or more conductive bristles of the brush with the conductive elements of the part.

2. The insulation inspection system according to claim 1, wherein: The set of input terminals includes a positive terminal and a negative terminal; and The capacitor and a first resistor of the pair of resistors are connected in series between the positive terminal and the negative terminal.

3. The insulation inspection system according to claim 2, wherein: The set of terminals includes a common terminal separate from the positive terminal and the negative terminal; and A second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

4. The insulation inspection system according to claim 1, wherein: The set of terminals includes a positive terminal, a negative terminal, and a common terminal; The circuit is implemented as a voltage and current balance circuit and includes the pair of resistors and the capacitor connected in series between the positive terminal and the common terminal; A first resistor of the pair of resistors and the capacitor are connected in series between the positive terminal and the negative terminal; And A second resistor of the pair of resistors is connected between the negative terminal and the common terminal.

5. The insulation inspection system according to claim 4, wherein the capacitor is connected across the power supply and between the positive terminal and the negative terminal.

6. The insulation inspection system according to claim 5, wherein: The first resistor includes i) a first end connected to the first end of the capacitor, and ii) a second end connected to the first of the set of input terminals and to the brush; And The second resistor includes i) a first end connected to the second of the set of input terminals, connected to the second end of the capacitor, and connected to the part, and ii) a second end connected to the third of the set of input terminals.

7. The insulation inspection system according to claim 6, wherein: The first end of the capacitor is connected to the positive terminal of the power supply; and The second end of the capacitor is connected to the negative terminal of the power supply.

8. The insulation inspection system according to claim 6, wherein leads are connected between: i) the second of the set of input terminals, the first end of the second resistor, and the second end of the capacitor, and ii) one or more three-phase contacts of the part.

9. The insulation inspection system according to claim 1, further comprising an analog-to-digital converter connected to the circuit and configured to convert an analog signal output from the circuit into a digital signal, wherein the control module is configured to detect when a short circuit exists between the conductive elements of the part and one or more conductive bristles of the brush based on the digital signal.

10. The insulation inspection system according to claim 1, wherein the control module is configured to generate at least one of a message or an alarm when a short circuit is detected between the conductive element of the part and the one or more conductive bristles.

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