INTEGRATED INSULATION TEST SYSTEM WITH CONDUCTIVE BRUSHES AND VOLTAGE AND CURRENT COMPENSATION CIRCUITS

Abstract

An insulation testing system includes: conductive brushes arranged to brush the insulated portions of a part under test; voltage and current balancing circuits connected to the conductive brushes, each of the voltage and current balancing circuits configured to detect a short circuit between one or more bristles of the conductive brushes and an exposed conductive element of the part; and a control module configured to detect a defect in the insulating material of the part in response to the detected short circuit.

Description

INTRODUCTION

[0001] The information provided in this section is intended to provide a general context for the disclosure. The work of the presently named inventors, to the extent described in this section, as well as those aspects of the description that do not otherwise qualify as prior art at the time of filing, are neither expressly nor implicitly acknowledged as prior art to the present disclosure.

[0002] The present disclosure relates to continuity testing systems and, more particularly, to insulation testing systems for testing stator windings and other electrical components.

[0003] Electric vehicles and hybrid vehicles contain traction motors for propulsion purposes. Each of the traction motors contains a stator and a rotor with corresponding windings and conductive bars. The windings and / or the conductive bars may be insulated (e.g., have an outer insulating coating). During manufacturing, including the formation of parts and components and assembly, the insulating coatings may not be formed properly or may be nicked, scratched, abraded, etc. This may result in sections of the insulating coatings being missing and / or removed, exposing electrically conductive elements. This exposure may cause a short circuit, impair motor performance, and / or reduce motor life. SUMMARY

[0004] An insulation testing system is disclosed, including: conductive brushes arranged to brush the insulated portions of a part under test; voltage and current balancing circuits connected to the conductive brushes, each of the voltage and current balancing circuits configured to detect a short circuit between one or more bristles of the conductive brushes and an exposed conductive element of the part; and a control module configured to detect a defect in the insulating material of the part in response to the detected short circuit.

[0005] According to other features, the insulation test further includes analog-to-digital converters configured to receive analog signal outputs of the voltage and current balancing circuits.

[0006] According to other features, the control module is configured to i) simultaneously monitor the digital outputs of the analog-to-digital converters and ii) simultaneously determine whether a defect exists at a location of a portion of each of the conductive brushes.

[0007] According to other features, the control module is configured to i) track the position of each of the conductive brushes relative to the part as the part is moved relative to the conductive brushes, and ii) determine a location of the detected defect based on the tracked position of the corresponding one of the conductive brushes relative to the part.

[0008] According to other features, the control module is configured to i) track the position of each of the conductive brushes relative to the part as the conductive brushes are moved relative to the part, and ii) determine a location of the detected defect based on the tracked position of the corresponding one of the conductive brushes relative to the part.

[0009] According to further features, the insulation testing system further includes a display. The control module is configured to indicate the detection of the defect on the display.

[0010] According to other features, the insulation testing system further includes an acoustic device. The control module is configured to indicate the detection of the defect via the acoustic device.

[0011] According to other features, each of the voltage and current balancing circuits includes a pair of resistors and a capacitor.

[0012] According to other features, the insulation testing system further includes analog-to-digital converters. Each of the analog-to-digital converters includes a set of input terminals. Each of the voltage and current compensation circuits includes a pair of resistors and a respective capacitor connected in series between two terminals of the set of input terminals of the corresponding one of the analog-to-digital converters.

[0013] According to other features, the pair of resistors of each of the voltage and current balancing circuits includes a first resistor and a second resistor. The set of input terminals of each of the analog-to-digital converters includes a positive terminal, a negative terminal, and a common terminal. The first resistor of each pair of resistors includes i) a first end connected to a respective one of the positive terminals and to a respective one of the conductive brushes, and ii) a second end connected to a first end of the respective capacitor. The second resistor includes i) a first end connected to a respective one of the common terminals, and ii) a second end connected to a second end of the respective capacitor and to the part.

[0014] According to other features for each of the voltage and current balancing circuits: the first end of the respective capacitor is connected to a positive terminal of a power source; and the second end of the respective capacitor is connected to a negative terminal of the power source.

[0015] According to other features, for each of the voltage and current balancing circuits, a line is connected between i) the negative terminal of the voltage and current balancing circuit, the second end of the second resistor and the second end of the respective capacitor and ii) one or more 3-phase contacts of the part.

[0016] According to other features, the capacitors of the voltage and current balancing circuits are connected in parallel and to the same power source.

[0017] According to other features, one end of each of the capacitors is connected to a wire and to a negative terminal of the same power source. The wire is connected to the part.

[0018] According to other features, the insulation testing system further includes at least one motor configured to i) move the part relative to the conductive brushes, and / or ii) move one or more of the conductive brushes with respect to the part. The control module is configured to i) control the at least one motor to follow a motion profile, and ii) during movement of the part and / or the one or more conductive brushes, detect the defect in the insulating material of the part due to a short circuit between one or more conductive bristles of the conductive brushes and the exposed conductive element of the part at a location of the defect.

[0019] According to other features, the insulation testing system further includes: a frame; and a support mounted to the frame and configured to hold the part relative to the conductive brushes. The conductive brushes are mounted to the frame relative to the part.

[0020] According to other features, an insulation testing method is disclosed, including: connecting a lead to a part to be tested; at least one of i) moving the part relative to the conductive brushes and ii) moving the conductive brushes relative to the part; brushing the insulating material of the part via the conductive brushes while performing the at least one of i) moving the part relative to the conductive brushes and ii) moving the conductive brushes relative to the part; detecting at least one short circuit between one or more bristles of the conductive brushes and an exposed conductive element of the part via voltage and current balancing circuits, the voltage and current balancing circuits being connected to the conductive brushes; and detecting at least one defect in the insulating material of the part in response to the detected at least one short circuit.

[0021] According to other features, the insulation test method further includes: compiling data collected via the voltage and current balancing circuits and generating a message including the compiled data; and indicating the message.

[0022] According to other features, indicating the message includes displaying the compiled data, generating an audible alarm, or transmitting the compiled data to a network device.

[0023] According to other features, the insulation testing method further includes removing at least one of the conductive brushes used to detect the defect from the part after detecting the defect to return the at least one of the conductive brushes to a rated voltage before the at least one of the conductive brushes is used again to detect another defect.

[0024] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present disclosure will be more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a bottom view of a portion of a stator illustrating an exemplary defect in an insulating coating; Fig. 2 is a schematic view of an exemplary insulation testing system testing a stator and including a voltage and current balancing circuit, according to the present disclosure; Fig. 3 is a perspective view of an exemplary partial insulation test stand including a partial turntable and movable and stationary brushes in accordance with the present disclosure; Fig. 4 a side cross-sectional view of the partial insulation test frame according to Fig. 3; Fig. 5 is a cross-sectional view of an exemplary 'U'-shaped brush assembly having three brushes with respective sets of bristles in accordance with the present disclosure; Fig. 6 is a partially exploded perspective view of an exemplary straight brush according to the present disclosure; Fig. 7 is a graphical representation of an exemplary insulation testing system testing a stator in accordance with the present disclosure; Fig. 8 illustrates an exemplary insulation testing method for detecting, marking, identifying, and reporting defects in accordance with the present disclosure; Fig. 9 an exemplary defect indication procedure according to the present disclosure; and Fig. 10 is a functional block diagram of another partial insulation test stand including movable brushes and a stationary subcarrier according to the present disclosure.

[0026] Reference numerals may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0027] During manufacturing, motors may be tested to detect defects, such as defects in the insulating coatings of electrical elements in a stator. The insulating coatings may be inspected visually. This may involve a quality control technician using a magnifying glass to visually inspect for defects in the stator's insulating coatings. Such testing is labor-intensive and subject to the technician's limitations. A continuity tester may be used, which applies a voltage to the stator and detects if a short circuit exists. An electric current will flow between the stator and the continuity tester if the insulating material is missing at the point where the tester touches the stator.

[0028] The continuity tester may include a brush with conductive bristles. The bristles can be moved over various sections of the stator, brushing them to detect short-circuit locations (i.e., defect locations) where insulating material is missing. The opposite can also occur if the part (or stator) is moved by the bristles while the brush is stationary. A circuit is used to monitor changes in voltage across the brush. The voltage drops considerably when a short circuit occurs. There are large voltage and current fluctuations between when there is no short circuit and when there is a short circuit.

[0029] Large voltage and current fluctuations in a circuit can be damaging to components over time if not managed properly. Consequently, components can degrade over time, and this degradation can negatively impact circuit operation. An A / D converter, for example, may have specific voltage and current limitations for operation based on what is used. If there is any resulting drift in the circuit components, such as resistors or other circuit components, this can lead to voltage response behaviors that can cause problems setting voltage thresholds and improperly detecting a short circuit. Deterioration of the circuit components can cause voltage drift, which can subsequently lead to undetected defects.The drift therefore requires circuit adjustments and periodic recalibration, which includes threshold adjustments. 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 a nominal voltage and / or a normally expected voltage (e.g., 24 V). The threshold can be set to less than or equal to 20% of the nominal voltage.

[0030] Drift can also lead to unsafe current levels. If circuit components deteriorate over time and a resulting change in the circuit's expected current occurs, this can lead to current levels in the circuit that may exceed a threshold for perceived and / or actual bodily injury. Furthermore, higher than expected current levels can be harmful to the parts and brush, even if human exposure is mitigated.

[0031] The examples set out here include an insulation test system comprising i) a partial insulation test frame with one or more continuity test brushes (referred to herein as brushes) and ii) one or more corresponding voltage and current compensation circuits as described in the Fig. 2 and Fig. 7. The brushes are mounted on the partial insulation test rig along with the part to be tested. The part is moved relative to the one or more brushes, or the brushes are moved relative to the part so that the bristles of the one or more brushes contact exposed conductive elements of the part at the locations where insulating material is missing. The voltage and current balancing circuits provide balanced voltage responses at nominally low current levels, which are detected across the bristles of the continuity test brushes used to detect defects (or short circuits). The voltage and current balancing provides stability, improves the longevity of the circuit components, and offers enhanced functionality that enables the insulation test system to be used in various applications while remaining safe for human contact.In addition to the hardware described above, the insulation testing system also includes an algorithm for marking defective parts. This algorithm improves sensitivity for better defect detection.

[0032] The examples include an automated system with a turntable for holding a stator and a cradle for holding multiple brushes for inspecting the sides of a welded end and the sides of a crown end of the stator while rotating the stator. The stator is located on the turntable, with the lugs and / or end faces of the stator held to the turntable via brackets, as described below. Multiple brushes of different types are used to contact the sides of the sections of the stator, such as the three sides of the welded end. According to one embodiment, this is done to ensure that the insulating material completely covers the welds and / or bare wires of the welded end or other section being inspected. Multiple brushes can be used to brush other sections of the stator, such as the wire insulation at the crown end of the stator.The brushes are designed so that the bristles contact the entire crown area and detect exposed wires within the crown. The test can exclude testing of a stator busbar. The brushes are designed to prevent short circuits between the bristles and the stator core.

[0033] Each of the voltage and current compensation circuits improves safety flexibility by incorporating a capacitor for voltage distribution and a pair of appropriately sized resistors. The resistance values ​​of the pairs of resistors are chosen to produce low current responses. The capacitors and resistors are connected across the common, negative, and positive terminals of the analog-to-digital converters (A / D converters). The resistor values ​​are chosen to produce low current responses during all operation and / or at all operating points of the voltage and current compensation circuits. The low current responses make the test setup safe for an operator. The capacitors produce open-circuit conditions when no electrical short circuit exists. If a short circuit is detected using a brush (e.g.,a brush with carbon bristles), a voltage is dropped across the positive end of a corresponding capacitor, resulting in some voltage drop across the corresponding resistors, so that the voltages at each positive and negative terminal of the corresponding A / D converter remain within a predetermined voltage range (e.g., ±13 V) with respect to a voltage at a common A / D terminal.

[0034] The resistor values ​​are selected so that the current throughout the voltage and current compensation circuits is maintained below a predetermined current (e.g., less than or equal to 25 mA, which is imperceptible to human touch) during a short circuit. From the standpoint of an incoming analog voltage signal, this would maintain the positive terminals of the A / D converters at the rated operating voltage (e.g., 24 V) and maintain the negative terminals of the A / D converters at 0 V when no short circuit is present. If a break in the insulation occurs, i.e., if the connection from the brush to the phase conductor is short-circuited, the following changes occur in a corresponding one of the voltage and current compensation circuits. The corresponding positive A / D terminal is forced towards 0 V.It is noteworthy that the positive A / D terminal cannot quite reach 0 V due to the intermittent contact between the brush bristles, but in the case of a stable short circuit, the positive A / D terminal is forced to 0 V. A defect is detected when the positive A / D terminal drops to or below a predetermined threshold (e.g., 5 V) or lower compared to the base voltage or the nominal voltage without a short circuit (e.g., 24 V).

[0035] Because the negative A / D terminals are maintained at 0 V, there is a 0 V difference between the positive and negative A / D terminals of the A / D converters, and consequently, the common A / D terminals are also at 0 V. As a result, the resistors (hereinafter referred to as resistors R2, R4, R6, ..., RM) connected across the negative and common A / D terminals of the A / D converters experience a 0 V drop (no current flow).

[0036] When defects are detected, charge is available for the corresponding capacitors to discharge on demand, rather than having a power source supplying the rated voltage directly connected to the short circuit (or defect). This allows a constant voltage drop across each of the capacitors to be maintained while minimizing the amount of current flow in each branch of the voltage and current balancing circuits because the corresponding brushes make intermittent contact with the defects. This is accomplished by maintaining the resistor-capacitor (RC) time constants sufficiently long so that discharging the capacitors does not cause large fluctuations in the voltage drops across the capacitors during the period in which intermittent contact is made between the brushes and the defective areas. As an example, each of the time constants may be 24 seconds.This results in the resistors (hereinafter referred to as resistors R1, R3, R5, ..., RN) connected between i) the capacitors and ii) the positive A / D terminals and the brushes mainly experiencing the voltage drops when short circuit conditions occur.

[0037] To ensure that the current in the circuit does not exceed anything the human body could perceive, resistors R1, R3, R5, ..., RN are selected so that, when a short circuit occurs, the current does not exceed a threshold value (e.g., 1 milliampere (mA)). This voltage and current balancing operation at all operating points enables the entire voltage and current balancing circuits to be both safe for humans to touch and not introduce current or voltage levels that would damage either the brush bristles or any part under test. The current and voltage levels remain below predetermined thresholds to prevent, for example, arcing.

[0038] If a short circuit is present, the corresponding capacitor can be discharged at a reasonable rate for a fast, stable measurement. Current flows through the resistors and provides an analog voltage measurement for the corresponding A / D converter. Once the brush is removed from the defective area and the short circuit is no longer present, the capacitor is charged until it returns to an open-circuit state.

[0039] The voltage and current balancing circuits prevent degradation of the circuit components by preventing large voltage and current fluctuations across the circuit components in the event of a short circuit. The capacitor and resistor values ​​are selected for improved circuit performance and are chosen to prevent degradation of the circuit components due to parasitic voltages across the resistors. The values ​​are selected to prevent drift in the values ​​of the circuit components. This prevents larger than expected voltage drops and arcing across the brush bristles.

[0040] An electrical circuit design and defect detection analysis algorithm are disclosed to enable the automated system to detect nicks and other defects in stator insulation. Multiple brushes are used to simultaneously test the welded and crown ends of a stator. The electrical circuit accommodates multiple brushes and tracks the analog electrical responses of multiple voltage and current balancing circuits. The voltage and current balancing circuits enable tracking of analog electrical responses. Multi-channel analog-to-digital conversions are performed while maintaining electrical safety parameters. Additionally, the defect detection analysis algorithm and a human-machine interface display are configured to enable simultaneous detection, identification, and reporting of defects, including flagging of defects to an end user.

[0041] Fig. 1 shows a section 100 of a stator. The stator contains welded wire pairs coated with an insulating material. The section 100 contains a defect 102 in which a portion of the insulating coating 104 is missing and conductive material 106 of a wire is exposed. Fig. 1, a lower (or welded) end of the stator is shown. The stator includes a lamination stack (or body) 110 with a bottom surface 112 and a plurality of lugs (one lug 114 is shown in Fig. 1). As an example, the insulating coating 104 may be an epoxy.

[0042] Fig. Figure 2 shows an insulation testing system 200 testing a stator 202. The insulation testing system 200 includes a human-machine interface (HMI) 204 and a voltage and current balancing circuit 206 connected to a power source 208. The HMI 204 may 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 includes LEDs 222 and / or other visual display 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 balancing circuit 206. The control module 210 detects defects when the analog output signal across the positive and negative terminals 223, 226 (or the corresponding digital signal) of the A / D converter 212 falls below the threshold voltage (e.g., 5 V or 20% of the nominal voltage or normally expected voltage (e.g.,24 V). The normal expected voltage without a detected defect may be 24 V. The control module 210 may indicate the detection of defects via the display 218 and the audible device 220. The detection of a defect, the change (or drop) in voltage, the time of detection, and / or other related information may be stored in the memory 214. As one example, the detection of the defect may be stored along with a nearby location of the defect relative to one or more reference points on the stator 202.

[0043] The display 218 provides a visual aid to indicate the detection of a defect. This also provides an indication of when a defect is detected. The audible device 220 may provide a loud sound, such as a loud alarm signal, when a defect is detected. The audible device 220 may include, for example, a speaker. The control module 210 may report the detected defects and corresponding information stored in the memory 214 via the transceiver 216 to one or more network devices located remotely from the HMI 204.

[0044] The voltage and current balancing circuit 206 includes resistors R1, R2, and a capacitor C. Resistor R1 has i) a first end connected to a first (or positive) terminal of the A / D converter 212 and to the brush 228, and ii) a second end connected to a first end of the capacitor C and to a positive terminal of the power source 208. Resistor R2 includes i) a first end connected to the second (or negative) input terminal 226 of the A / D converter 212, a second end of the capacitor, one or more of the 3-phase contacts 224, and a negative terminal of the power source 208, and ii) a second end connected to a third (or common) terminal COM of the A / D converter 212. The common terminal COM is separate from each of the terminals 223, 226 and is not connected to any of them.A line 225 is connected between i) the negative terminal 226, the first end of the resistor R2, and the second end of the capacitor C, and ii) the one or more 3-phase contacts 224. The first end of the capacitor C is connected to the positive terminal of the power source 208. A second end of the capacitor C is connected to the negative terminal of the power source 208.

[0045] 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. According to 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 stator 202.

[0046] 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). According to one embodiment, R1 is 24 kΩ, R2 is 470 kΩ, and C is 1000 μF. The resistance values ​​of the resistors and the capacitance of the capacitor are selected to provide the RC time constant mentioned herein. According to one embodiment, the resistance values ​​of resistors R1, R2 are selected to limit an amount of current flowing through stator 202, voltage and current balancing circuit 206, and brush 228.The resistance values ​​of resistors R1 and R2 and the capacitance of capacitor C are chosen i) to prevent arcing and sparking at the bristles 230 when a defect (short circuit) occurs, and ii) to ensure proper current balance in the circuit during all test conditions to maintain it safe for human contact (less than 1 mA). The resistance values ​​of resistors R1 and R2 can be chosen, for example, to prevent the current through the circuit 206, the brush 228, and the stator 202 from exceeding a predetermined threshold.

[0047] The resistor values ​​are chosen to limit the current during all aspects of operation and to balance the voltage load allowed across the channels of the A / D converter 212, such as that associated with terminals 223, 226. According to one embodiment, and regardless of whether a defect is present (a short circuit occurs) or no defect is present (no short circuit), the current is maintained between 25 microamperes (µA) and 1 mA due to i) the arrangement and selected values ​​of resistors R1 and R2 along with capacitor C in the voltage and current balancing circuit 206 with respect to the power source 208 (e.g., 24 VDC power supply) and ii) the A / D voltage channel limits between different channels with respect to the common A / D terminal COM. The resistances of R1 and R2 can be changed based on the A / D behavior limits to maintain the described current behavior.As an example, the channel boundaries may be such that the A / D channels of the A / D converter are within ±10-13 V of the common A / D terminal COM. According to one embodiment, the channel boundaries are such that the A / D channels are within ±10.2 V of the common A / D terminal COM.

[0048] The nominal capacitance of capacitor C is chosen to provide a sufficiently long RC time constant in conjunction with the R1 value chosen for current level reasons. This is done to provide a stable nominal voltage (e.g., a stable 24 V) for the voltage and current compensation circuit 208 within the time window it takes to determine whether a short circuit has occurred. The R1 * C value can provide a time constant of approximately 24 seconds. This provides a sufficiently long time constant that does not need to be further increased with a larger C value, although the time constant can be further increased. If the time constant is too small, the charging and discharging behavior of capacitor C would affect circuit operation in that the nominal voltage would no longer remain at a stable 24 V if a fault occurs.This can make it difficult to assign a specific defect detection threshold because the voltage response would be convolved with the behavior of the capacitor C.

[0049] The capacitance of capacitor C influences the rate of change of the current flowing through stator 202, voltage and current balancing circuit 206, and brush 228. Capacitor C is included as protection for brush 228 and bristles 230, preventing a current surge from power source 208 to the short circuit location. When no short circuit exists, capacitor C is charged. When a short circuit exists, capacitor C discharges. Due to the RC time constant used, capacitor C does not fully discharge. This helps limit the current in the circuit during a short circuit event. After discharging, power source 208 recharges capacitor C. If the bristles are moved, the short circuit typically only lasts a short period of time. Without capacitor C, resistors R1 and R2 may degrade due to a short circuit and a current surge through resistors R1 and R2.The capacitance and resistance values ​​can also be selected based on the application to provide low current consumption for safe use by the operator. For example, the capacitance of capacitor C and the resistance values ​​of resistors R1, R2 can be selected to match different brush head designs used to detect defects. According to one embodiment, the brush is designed to have a low impedance compared to the circuit components. The insulation testing system 200 can adapt to brushes with various different designs.

[0050] The HMI 204 and / or the A / D converter 212 detect an analog voltage at terminals 223, 226. Filtering of the A / D signal is performed by data sampling to remove noise associated with the electrical behavior of the brush bristles. A voltage from the power source 208 is provided across capacitor C, which, in conjunction with resistor R1, provides a stable voltage to the brush 228. One of the 3-phase contacts 224 of the stator 202 is connected to line 225. When one or more of the conductive bristles 230 come into contact with an exposed conductive element of the stator 202, current flows from one of the 3-phase contacts 224 through the stator 202 and to one or more of the bristles 230 in contact with the exposed conductive element. The 3-phase contacts 224 include three contacts; one for each phase of the 3-phase stator 202.According to one embodiment, the three-phase contacts 224 are connected to each other so that current can flow through each of the phases of the stator 202. According to another embodiment, the voltage is provided to one of the three-phase contacts 224 of the stator 202, with the brush connected to the line 225.

[0051] The insulation testing system 200 may be used to test a crown end 240 of the stator 202, as shown, a welded end 242, and / or another portion of the stator 202. The insulation testing system 200 may also be used to test individual electrical components and / or elements, an example of which is shown in Fig. 3. The crown end 240 extends upward from a lamination stack 244. The welded end extends downward from the lamination stack 244. The bristles 230 can be moved along various components of the stator 202 to detect locations where insulating material is missing.

[0052] The insulation testing system 200 includes software and hardware with tunable A / D voltage thresholds used to identify defects. As an example, the threshold for identifying a defect may be set to 5 V, but it may vary for other applications. The control module 210 implements a detection algorithm that detects when the voltage across terminals 223, 226 falls below one of the A / D voltage thresholds and generates a visual and / or audible signal to identify the detected defect.

[0053] The voltage and current balancing circuit described above minimizes current levels at all operating points, regardless of whether a short circuit is present. The inclusion, selection, and arrangement of resistors and capacitors as described prevents large voltage and current fluctuations and consequently prevents component degradation over time. This keeps current levels below the thresholds associated with perceived and / or actual damage.

[0054] Fig. Figure 3 shows a partial insulation test stand 300 that includes a partial turntable assembly (which may be referred to as a partial carrier) 302, a frame 304 with the rails 306, the brush holding elements 308, a first 'U'-shaped brush assembly 310, a first straight brush 312, a second straight brush 314, and a second 'U'-shaped brush assembly (or 'U'-shaped brush) 316. The brushes 310 and 312 in combination are referred to as a gamma brush. Although the Fig. 3-4 show a frame configured to rotate a part and hold the brushes at fixed positions. The frame can be modified to hold the part at a fixed position and move the brushes relative to the part. An example of this is shown in Fig. 10 shown.

[0055] The partial rotary table arrangement 302 according to Fig. 3 includes a turntable base / housing 320 and a support plate 322 that rotates relative to the base 320 (or turntable). The part turntable assembly 302 may include part support brackets 324. The support brackets 324 are attached to the support plate 322 and to a part to be tested 326 (e.g., a stator of a motor). The support brackets 324 may be 'C'-shaped and attached to the lugs 328 of a stator lamination stack 329. The support brackets 324 may be replaced with pins with a tapered end if only one side is being tested at a time. If pins are used, the stator would have to be turned over to test the other side of the stator. The part 326 rotates with the support plate 322.

[0056] The part turntable assembly 302 is part of an automated system that includes the turntable 320 with the support plate 322 (or pallet) on top. A palletizing system may use at least one pallet to load the part to be tested (or the stator) from the turntable 320, with a saddle capable of bringing the pallet with the stator on top of the turntable 320. The stator may also be transferred to a fixture located on the turntable 320 (either by a robot or a human). The system's brushes, described below, can be activated to move to control locations ready to contact specific test portions of the stator wires. The angular rotation of the stator is determined by the arrangement of the one or more brushes to test exposed insulated wires of the stator.One or more other brushes may be used by a human or a robot to clean any exposed insulated wires of the stator, e.g. using the system of . Fig. 2 to be checked.

[0057] The stator includes a crown end 330 and a welded end 332. The crown end 330 is tested using the first 'U'-shaped brush assembly 310 and the straight brushes 312, 314. The first 'U'-shaped brush assembly (or first 'U'-shaped brush) 310 includes three brushes arranged in a 'U' shape, which are formed as part of a gamma brush. The gamma brush assembly also includes the three brushes and the straight brush 312. A single brush member 334 holds the bristles 336 of the three brushes and the bristles 338 of the straight brush 312. The bristles 336 brush against the outer, upper, and inner surfaces of the crown end 330. The bristles 338 brush against an inner surface of the crown end 330. The gamma brush assembly is movable between an extended state and a stowed state, as indicated by arrow 339. This can be accomplished, for example, by loosening or tightening a clamp 340 of a swing arm 341 via a handle 343.According to one embodiment, terminal 340 includes a motor controlled by a control module (e.g., the control module of . Fig. 7) or it is attached to the motor. The brush holding elements 308 can be moved laterally along the corresponding one of the rails 306, as indicated by arrows 342 and 345, respectively. According to one embodiment, the brush holding elements 308 have slots that allow the brush holding elements 308 to be moved closer to or farther away from the stator to obtain proper contact with the stator. The brush 314 has the bristles 344. The bristles 336, 338, and 344 can be held in the grooves of the corresponding brush holding elements (or brush holders) 308, which can have internal grooves for the ends of at least some of the bristles 336, 338, and 344.

[0058] The second 'U'-shaped brush assembly 316 includes three brushes arranged in a 'U' shape and held by a single brush member 347. The three brushes of the second 'U'-shaped brush assembly 316 brush against the inside, bottom, and outside of the welded end 332. Another 'U'-shaped assembly is included and is in Fig. 4 shown.

[0059] The stator has a busbar 350 with three-phase contacts 352. The part to be tested (or the stator) 326 can be rotated so that the brushes of the individual brush element 334 do not come into contact with the busbar 350. The part 326 can be rotated to test the stator crown portion not covered by the busbar 350. This represents a rotation of more than 180° and a rotation of less than 360°. As shown, the individual brush element 334 is at a 90° position relative to the part 326. With the rotational movement of the part 326 set forth above, the brushes 310, 312 can brush 360° of the inner side surface of the crown end 330. The gamma brush assembly can be converted to the stowed state to allow the brush 314 to brush against 360° of the outside of the crown end 330. To perform this operation, the member 326 is rotated 360°.The second 'U'-shaped brush assembly 316 also brushes 360° of the inner, lower, and outer surfaces of the welded end 332. The data collected for the outer side surface of the crown end 330 may be collected while the data for the inner, lower, and outer side surfaces of the welded end 332 is collected.

[0060] Fig. 4 shows the partial insulation test stand 300, which includes the partial turntable assembly 302, the frame 304 with the rails 306, the brush support members 308, the first 'U'-shaped brush assembly 310, the first straight brush 312, the second 'U'-shaped brush assembly 316, and a third 'U'-shaped brush assembly (or third 'U'-shaped brush) 400. The first 'U'-shaped brush assembly 310 includes the bristles 336, which comprise the bristle sets 336A, 336B, 336C of the corresponding brushes.

[0061] The partial turntable assembly 302 includes the base 320 and the support plate 322. The support plate 322 rotates via a shaft 402 through a (in Fig. 3) motor 401, which is controlled by the control module Fig. 7 can be controlled. A support rod 404 extends through the shaft 402 and is connected to a support member 406, which is connected to and supports the 'U'-shaped brush assemblies 316 and 400. The 'U'-shaped brush assemblies 316 and 400 include the 'U'-shaped members 345, 408 and the laterally extending members 410, 412 connected to the support member 406. The 'U'-shaped brush assemblies 316 and 400 further include the bristle sets 420A, 420B, 420C and 422A, 422B, 422C. The bristles of the bristle sets 420A, 420B, 420C and 422A, 422B, 422C may contain bristles of different lengths.

[0062] According to the example shown, the part 326 to be tested is shown as the above-mentioned stator, which includes the crown end 330, the welded end 332, and the busbar 350. The part 326 is held to the support plate 322 via the 'C'-shaped support brackets 324.

[0063] Fig. Figure 5 shows a 'U'-shaped brush assembly 500 with a mounting design for three brushes 502, 504, 506 with the respective bristle sets 508, 510, 512. The brushes 502, 504, 506 have respective wires 514, 516, 518 connected to corresponding voltage and current balancing circuits, examples of which are shown in Fig. 7. The bristles of the bristle sets 508, 510, 512 are conductive and flexible and are held by crimp connections and / or the bristle holding elements 520, 522, 524. The brushes 502, 504, 506 have interlocking grooves that allow them to remain attached to one another and to move similarly to some of the Fig. 3 shown brushes with a laterally extending element.

[0064] The bracket design (or bracket) can be adapted for different stator models, different stator sizes of the same family, etc. The bracket includes the plate 521, which is attached to the brush bodies, with the brush bodies having first respective channels for the wires 514, 516, 518 and second respective channels for attaching the bristle retaining elements 520, 522, 524. The bracket can be 'U'-shaped, flat-shaped, or have another shape to adapt it to the detection area of ​​the stator's exposed wires. The wires 514, 516, 518 are used to monitor the voltages at the brushes 502, 504, 506, respectively, to determine the location of a defect (or to determine where a short circuit is detected).

[0065] The bristles (or fibers) of the brushes 502, 504, 506 may be carbon fibers with one end embedded in epoxy to prevent the carbon fibers from "falling out" of the bristle retaining elements 520, 522, 524 and / or breaking. The epoxy may be conductive and may contain additives to increase the viscosity and / or increase the electrical conductivity of the epoxy and prevent wicking (or movement of the epoxy along the fibers). The other additives may be zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), or three-dimensional (3D) nanomaterials, depending on the shape and size of the additive. They may include both nanoparticles and micro-sized particles, such as metallic, non-metallic, polymeric, and non-polymeric particles. The other additives may include such nanomaterials and carbon-based particles, such as carbon-based particles. B.Graphene, graphene nanoplatelets, graphite, fullerene, carbon nanotubes, carbon black, and carbon dots. The epoxy can increase the stiffness of the bristles. Fig. 6 shows an exemplary structural arrangement of a brush that can be used for each of the brushes 502, 504, 506.

[0066] Fig. 6 shows a straight brush 600 and the corresponding bristles 602, a conductive crimp layer 604, an epoxy layer 606, and a conductive strip 608. The epoxy layer 606 is outlined and shown in a transparent form to show the conductive crimp layer 604. The bristles 602 include first ends 610 and second ends 612. The first ends 610 are uncoated and / or not embedded in epoxy. The second ends 612 are coated and embedded in the epoxy of the epoxy layer 606. The second ends 612 are coated with the epoxy. The epoxy may be conductive and connects the second ends 612, the conductive crimp layer 604, and the conductive strip 608. The conductive crimp layer 604 is wrapped around at least three sides of the second ends 612 and is crimped onto the bristles 602, holding them together. According to one embodiment, the conductive crimp layer 604 is wrapped around four sides of the second ends 612. Although this is Fig. 6, the conductive strip 608 is folded over the second ends 612 and covers at least one side of the conductive crimp layer 604. The conductive strip 608 covers three sides of the second ends 612. The conductive strip 608 is connected to a wire 614, which may be an output wire used to detect a short circuit.

[0067] The bristles 602 may contain carbon fibers, metal fibers, or other conductive fibers. The density, stiffness, and tear-out strength properties of the bristles can be selected and optimized. The conductive crimp layer 604 and the conductive strip 608 may be formed from metallic materials. According to one embodiment, the second ends 612, the conductive crimp layer 604, the epoxy layer 606, and the conductive strip 608 are arranged in a brush holder, solidified, and cured. Example brush holders are described in Fig. 5 shown.

[0068] Fig. 7 shows an insulation testing system 700 testing a stator 702. The insulation testing system 700 is related to the insulation testing system according to Fig. 2, but contains a partial insulation test arrangement 704, such as the partial insulation test frame 300 according to the Fig. 3-4, and a plurality of voltage and current compensation circuits 706 each for a plurality of brushes 708 of the partial insulation test arrangement 704.

[0069] The insulation testing system 700 includes an HMI 710. The HMI 710 includes a control module 711, the A / D converters 712 for the voltage and current balancing circuits 706, respectively, a memory 714, a transmitter / receiver 716, a display 718, and an audible device 720. The display 718 includes the LEDs 722 and / or other visual display and / or indicator elements. The control module 711 receives digital voltage data from the A / D converters 712, which receive the analog input signals from the voltage and current balancing circuits 706. The control module 711 detects defects when the analog output signals (or the corresponding digital signals) fall below the threshold voltage (e.g., 5 V or 20% of the nominal voltage or the normally expected voltage (e.g., 24 V)). The control module 711 may indicate the detection of defects via the display 718 and the acoustic device 720.The detection of a defect, the voltage change (or voltage drop), the time of detection, and / or other related information may be stored in memory 714, as described above and as further described below.

[0070] The partial insulation test assembly 704 includes the motors 730 and the brushes 732 and may also include the sensors 734. The motors 730 may include a motor for rotating a support plate for a part such as the stator 702. The motors 730 may further include motors i) for moving the brushes along the rails and / or relative to the respective portions of the part under test and / or ii) for moving the brushes between extended and stowed positions. The brushes 732 may include straight brushes, 'U'-shaped brushes, and / or other brushes. Some of the brushes may be implemented in gamma brush arrays. The sensors 734 may include motor encoders for determining the positions of the shafts of the motors 730, cameras for monitoring the locations of the brushes 732 relative to the part under test, speed sensors for monitoring the speed of one or more of the motors 730, and / or other sensors.

[0071] The stator 702 includes a crown end 740, a lamination stack 742, and a welded end 744. The crown end 740 extends from a top surface 746 of the lamination stack 742. The welded end 744 extends from a bottom surface 748 of the lamination stack 742. The stator 702 has three phases with respective 3-phase contacts 750.

[0072] Each of the voltage and current balancing circuits 706 includes i) a pair of resistors R1 and R2, R3 and R4, ..., or RM and RN, and ii) one each of the capacitors C1-CP, where M, N, and P are integers. The number of resistor pairs is equal to the number of capacitors.

[0073] Each of the resistors R1, R3, ..., RM has i) a first end connected to a first (or positive) terminal of a respective one of the A / D converters 712 and to a respective one of the brushes 732, and ii) a second end connected to a respective one of the capacitors C1-CP and to a positive terminal of the power source 760. The first ends of the capacitors C1-CP are connected to the resistors R1, R3, ..., RM and are connected to the positive terminal of the power source 760. The second ends of the capacitors C1-CP are connected to a negative terminal of the power source 760, to a respective one of the resistors R2, R4, ..., RN, to a second (or negative) terminal of a respective one of the A / D converters 712, and to one or more of the 3-phase contacts 750.

[0074] Each of the resistors R2, R4, ..., RN includes i) a first end connected to a third (or common) terminal of a respective one of the A / D converters 712, and ii) a second end connected to the second end of a respective one of the capacitors C1-CP, to the negative terminal of the power source 760, and to one or more of the 3-phase contacts 750 of the stator 702. A line 725 is connected between i) the negative terminals of the A / D converters 712, the second ends of the resistors R2, R4, ..., RN, and the second ends of the capacitors C1-CP, and ii) the one or more 3-phase contacts 750.

[0075] The resistors and capacitor of each of the voltage and current balancing circuits 706 are connected in series between the positive terminals of the A / D converters 712 and the common terminals of the A / D converters 712. According to the example shown, each of the capacitors C1-CP is connected between a respective one of the resistors R1, R3, ..., RM and a respective one of the resistors R2, R4, ..., RN. According to one embodiment, the resistors R1, R3, ..., RM and R2, R4, ..., RN are directly connected to a respective one of the terminals of the A / D converters 712 and directly connected to the corresponding one of the capacitors C1-CP. The resistors R2, R4, ..., RN can be directly connected to the stator 702. The resistors R1, R3, ..., RM can be directly connected to the brushes 732.

[0076] As an example, resistors R1, R3, ..., RM may each be 20-30 kiloohms (kΩ), resistors R2, R4, ..., RN may each be 400-500 kΩ, and capacitors R2, R4, ..., RN may each be 500-1500 microfarads (µF). According to one embodiment, resistors R1, R3, ..., RM may each be 24 kΩ, resistors R2, R4, ..., RN may each be 470 kΩ, and capacitors C1-CP may each be 1000 µF.

[0077] The resistance values ​​of resistors R1, R3, ..., RM, R2, R4, ..., RN and the capacitance of capacitors C1-CP are chosen to provide the RC time constants mentioned here. According to one embodiment, the resistance values ​​are chosen to limit the amount of current flowing through stator 702, voltage and current balancing circuits 706, and brushes 1-N. The resistance values ​​and capacitances are chosen to i) prevent arcing and sparking at the bristles of brushes 1-N when a defect (short circuit) occurs, and ii) ensure proper current balancing in the circuit during all test conditions to maintain safety for human touch (less than 1 mA). The resistance values ​​can be chosen, for example, to prevent the current through circuit 700, brushes 1-N, and stator 702 from exceeding a predetermined threshold.

[0078] The resistor values ​​are chosen to limit the current during all aspects of operation and to balance the voltage load allowed across the channels of the A / D converters 712, such as that associated with the positive and negative terminals of the A / D converters 712. According to one embodiment, and regardless of whether a defect is present (a short circuit occurs) or no defect is present (no short circuit), the current is maintained between 25 microamperes (µA) and 1 mA due to i) the arrangement and selected values ​​of the resistors along with the capacitors in the voltage and current balancing circuits 706 with respect to the power source 760 (e.g., 24 VDC power supply) and ii) the A / D voltage channel limits between different channels with respect to the common terminal COM. The resistor values ​​can be changed based on the A / D behavior limits to maintain the described current behavior.As an example, the channel boundaries may be such that the A / D channels of the A / D converters 712 are within ±10-13 V of the common A / D terminal COM. According to one embodiment, the channel boundaries are such that the A / D channels are within ±10.2 V of the common A / D terminal COM.

[0079] The nominal capacitances of the capacitors are selected to provide sufficiently long RC time constants in conjunction with the resistance values ​​of resistors R1, R3, ..., RM, which have been selected for current level reasons. This is done to provide a stable nominal voltage (e.g., a stable 24 V) for the voltage and current compensation circuits 706 within the time window required to determine whether a short circuit has occurred. The RC values ​​can provide time constants of approximately 24 seconds. This provides sufficiently long time constants that do not need to be increased further for larger C values, although the time constants can be increased further. If the time constants are too small, the charging and discharging behavior of the capacitors C1-CP would affect the circuit operation in that the nominal voltage would no longer remain at a stable 24 V if a defect occurs.This can make it difficult to assign a specific detection threshold because the voltage response would be convolved with the behavior of the capacitors C1-CP.

[0080] According to one embodiment, the resistance values ​​of resistors R1, R3, ..., RM and R2, R4, ..., RN are selected to limit the amount of current flowing through the stator 702, the voltage and current balancing circuits 706, and the brushes 732. The resistance values ​​of resistors R1, R3, ..., RM and R2, R4, ..., RN and the capacitances of capacitors C1-CP are selected to prevent arcing and sparking at the bristles of the brushes 732 when defects (short circuits) occur. The resistance values ​​of resistors R1, R3, ..., RM and R2, R4, ..., RN can be selected to prevent the current through each of the brushes 732 from exceeding a predetermined threshold.

[0081] The voltage and current balancing circuits 706 operate similarly to the voltage and current balancing circuit 206 according to Fig. 2. The brushes 732 can replace the brushes 310, 312, 314, 316, 400 according to the Fig. 3-4. The control module 711 monitors for defects detected via the voltage and current balancing circuits 706, the A / D converters 712, and the brushes 732.

[0082] Fig. Figure 8 illustrates an exemplary insulation test procedure for detecting, marking, identifying and reporting defects across multiple brushes (e.g., the brushes after the Fig. 3-4 and 7). The insulation testing method implements a defect detection analysis algorithm that includes the following operations. The operations can be performed iteratively. The operations shown with boxes in solid lines can be performed using the partial insulation test stand 300 according to the Fig. 3-4 or another frame similar to that of the partial insulation test frame 300, by the insulation test system 200 according to Fig. 2 and / or the insulation test system 700 according to Fig. 7. Although the operations are mainly related to the insulation test system 700 according to Fig. 7, the operations are applicable to other embodiments of the present disclosure.

[0083] At 800, line 725 is connected to the part to be tested, such as stator 702 or another electrical component. Line 725 can, for example, be connected to one or more of the 3-phase contacts 750.

[0084] At 802, the control module 711 begins rotating the part according to a motion profile, with the brushes passing over the insulated portions of the part. The part can be rotated in increments or in a continuous motion. The part can be rotated while performing the following operations. The brushes 732 are moved over the insulated portion of the part under test. This includes brushing the bristles of the brushes 732 on the insulated portions so that one or more of the bristles come into contact with any uninsulated (exposed) conductive material of the part. The exposed conductive material is at a voltage applied to the part by the power source 760. When one or more of the bristles touch an exposed portion of the part, a short circuit is created, and the control module 711 detects the voltage drop.The short circuit creates a steep voltage drop below the threshold level from the nominal level (or the normally expected level). The bristles maintain contact with the part while moving relative to the part.

[0085] At 804A, 804B, ..., 804P (collectively referred to as operation 804), the control module 210 begins monitoring the voltage at the terminals of the A / D converters 712 and consequently at the bristles of the brushes 732. This may include determining a location of the bristles of the brushes 732 relative to one or more reference points of the part under test. According to one embodiment, the bristles of the brushes 732 initially contact corresponding locations on the part for which the control module knows the coordinates, and then the brushes 732 are moved. As an example, the movement, which includes location and velocity information, may be tracked by the control module 711 based on the outputs of the sensors 734.

[0086] At 806A, 806B, ..., 806P (collectively referred to as an operation 806), the control module 811 determines whether a defect has been detected. If one or more defects have been detected, the operation 808A, 808B, ..., 808P (collectively referred to as an operation 808) is performed for the one or more brushes for which a defect has been detected; otherwise, the operation 812A, 812B, ..., 812P may be performed for the one or more brushes for which no defect has been detected. A defect is detected when there is a short circuit between one or more of the bristles of one or more brushes 732 and one or more exposed conductive elements of the part.If the part is a stator, a short circuit may be present between one or more of the bristles and one or more exposed wires of the stator, and consequently between the one or more bristles and one or more of the 3-phase contacts 750 of the stator 702.

[0087] At 808A, 808B, ..., 808P (collectively referred to as an operation 808), the control module executes a defect indication procedure described in Fig. 9 is illustrated.

[0088] At 900, the control module indicates the detected defects visually and / or audibly via one or more indicators, such as the display 718, the LEDs 722, and / or the audible device 720. According to one embodiment, a message is displayed via the display 718. The message may contain information regarding the detected defects, including the location of the defects, the time at which the defects were detected, the voltage drops across the A / D converters 712 experienced as a result of the defects, the rate of the voltage drops, how long the defects are detected, etc. According to another embodiment, the message is sent from the HMI 710 to another network device via the transceiver 716. The defects may be detected for short periods of time depending on the size of the defect and the speed of movement of the corresponding brushes relative to the part under test.The location of the defect can be specified with respect to one or more reference points on the part to be inspected.

[0089] As an example, a ring having clocked indices may be attached to the welded end 744, and / or the lamination stack 742 may have reference points. The indices and / or the reference points may be used to determine the locations of detected defects. According to one embodiment, the control module 711 indicates the defects by illuminating red LEDs (one for each defect) or by displaying red icons (one for each defect). For brushes that do not detect defects, green LEDs may be illuminated and / or green icons may be displayed. The display may include an LED and / or display an icon for each brush indicating whether a defect has been detected using that brush. According to another embodiment, the control module 711 indicates the defects by initiating an audible defect alarm signal.

[0090] At 902, the control module 711 records the information regarding the detected defects. At 904, the brushes 732 are removed from the part (i.e., moved to stowed positions away from the part). At 906, the voltage of the voltage and current balancing circuits 706 returns to the nominal levels.

[0091] At 908, the control module 711 stops indicating that a defect has been detected, thereby returning the one or more indicators to their normal states. The acoustic device 720, which may provide the acoustic notification (or alarm), is turned off, for example. The illuminated LEDs turn green or are turned off. The displayed icons indicating the presence of a defect change from red to green or are no longer displayed. The operation 810A, 810B, ..., 810P (collectively referred to as an operation 810) after Fig. 8 can be executed following operation 908.

[0092] At 810, the control module 711 may determine whether more of the part needs to be inspected. If so, operation 804 may be performed; otherwise, the method may end.

[0093] At 812, the control module 711 may compile the defect information for each of the detected defects, including the locations of the defects and other related information. The compiled information may be stored as a compiled information file in memory 714.

[0094] At 814, the control module 711 may report the compiled information in a compiled overall message about the presence of defects and / or portions thereof via the display 718 and / or the audible device 720.

[0095] The message and / or the compiled information may be transmitted to a remote network device via transceiver 716. This information may include the locations of the defects, identify one or more defect zones where defects are located, and / or other related information (e.g., any of the information set forth above). This may include an indication of the location of the defects on the part, the times at which the defects were detected, and / or other information indicating the locations of the defects.

[0096] Based on the detected defects and the corresponding information, the defects can then be inspected and repaired. The control module 711 can rotate the part to enable manual inspection and / or repair of a defect. If a defect is beyond repair and / or if there are too many defects, the part can be recycled or discarded. Based on the collected information, the control module 711 can indicate whether the part is repairable and / or whether the part should be recycled or discarded.

[0097] Fig. Figure 10 shows a partial insulation test stand 1000 containing movable brushes 1002 and a stationary partial support 1004 that holds a part 1006 in a fixed position. Any number of brushes may be included. The brushes may be of any of the types mentioned above. Fig. 10 is provided as an example and shows an example arrangement of brushes with respect to a part, where the brushes can be in various other arrangements with respect to the part. The part 1006 can be a stator or another type of part. The brushes 1002 can be held by brush holders 1008, which can be attached to one or more support members. An example support member 1010 is shown. One or more motors can be included to move the one or more support members and consequently the brushes 1002. The motors can be attached to a frame 1011. A motor 1012 is shown moving the support member 1010. The motors move the brushes 1002 with respect to the part. This movement can be a rotational movement or a linear movement. Motors can be included to move the brushes between an extended and stowed state.The brushes 1002 may be connected to the voltage and current balancing circuits of an insulation testing system, as shown in . Fig. 7. The sub-carrier 1004 may also be attached to the frame 1011.

[0098] The exemplary automated system disclosed herein detects nicks on the exposed wires at the welded and crown ends of an assembled stator. The brush holders are adjustable to handle different stator sizes of the same family and different types and designs of brush heads. This achieves a high degree of flexibility in meeting the requirements of a given application. The automated system can be configured with stationary brushes and rotate a stator relative to the brushes, or can be configured with a stationary stator support member and rotate (or move) the brushes relative to the stator. The brushes are configured to detect the exposed wires at the welded and crown ends. The brush holders are optimized for each specific stator size and design.According to one embodiment, the ends of the carbon fibers are embedded in an epoxy and inserted into the grooves of the brush holders. Additives (such as carbon black) may be used to increase the viscosity of the epoxy, prevent bristle tearing, provide low uniform interfacial resistance, and prevent wicking. The bristle lengths of the 'U'-shaped conductive brushes are selected for each intended use to avoid significant bristle overlap i) at the bend (or 90° angled) portions of the 'U'-shaped holders to allow the bristles to be properly deflected, and ii) at the contact portions (or contact ends) where the bristles touch the part under test.

[0099] The examples described above include a circuit design for multi-channel analog-to-digital conversion of the brush signals while maintaining electrical safety parameters for operators. The circuit design allows for simultaneous analog signal tracking for each brush integrated into the automated system. The multi-channel circuit design can include multiple brushes to fully test each isolated section of a part (perform an electrical test of each isolated section of a part).

[0100] An analysis algorithm for both defect identification and location is provided, monitoring the digitally converted signals from each brush individually while tracking the motion profile of either the brushes or the inspected part as the brushes or the part are moved (e.g., rotated) relative to each other. An HMI display is used for simultaneous defect detection and reporting (e.g., tagging). According to one embodiment, the locations of the detected defects are reported to a user and / or a remote network device when a repeatable motion profile is used for inspection.

[0101] The test circuit and analysis algorithm disclosed herein enable the automated system to test the insulation of the wires at both ends of a stator assembly for cuts, nicks, and other defects. The test circuit has enhanced circuit performance to prevent degradation of electrical circuit components due to parasitic voltages across the test circuit's resistors. The analysis algorithm is used to monitor the digitally converted signals from each brush individually, tracking the motion profiles of the brushes and / or the part under test as they are moved relative to each other for both defect identification and location approximation. An HMI display is updated for an end user to enable simultaneous brush detection and reporting to flag defects.The HMI display can be used as a visual aid to identify when and where a fault occurs. If a short circuit occurs, the corresponding fault can be indicated via the HMI on a screen and / or with an audible alarm.

[0102] Safety flexibility is enhanced by including capacitors in each analog-to-digital channel to distribute voltage within the circuit. Resistors with selected resistance values ​​are included to produce low current responses, making a test setup safe for an operator, and to prevent electrical arcing between the brush bristles and the part under test. The capacitors create open-circuit conditions when no short circuit conditions exist. When a short circuit (or short circuit condition) is detected by a brush, the voltage at the positive end of the corresponding capacitor drops, resulting in some voltage drop across the corresponding pair of resistors, so that the voltages of each positive and negative terminal of the corresponding A / D converter remain within a predetermined voltage range (e.g.,±13 V) with respect to a voltage at the common A / D terminal. Once the brush is removed from the short circuit location, the capacitor is charged until it returns to its open-circuit state. The voltage drop and the amount of current flowing through the circuit due to the short circuit are limited. This helps prevent circuit degradation and makes the circuit safe for human contact. The capacitor and resistor values ​​are set to meet application requirements while providing low current draw for safe use by an operator.

[0103] The foregoing description is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be implemented in various forms. Therefore, while this disclosure contains specific examples, the true scope of the disclosure should not be so limited because other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be recognized that one or more steps within a method may be performed in different orders (or simultaneously) without altering the principles of the present disclosure.Furthermore, although each of the embodiments has been described above with certain features, one or more of those features described with respect to any embodiment of the disclosure may be implemented in any of the other embodiments and / or combined with the features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with each other remain within the scope of this disclosure.

[0104] 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," "beside," "on top of," "over," "below," and "disposed." When a relationship between a first and a second element is described in the above disclosure, that relationship may be a direct relationship, with no other intervening elements present between the first and second elements, but it may also be an indirect relationship, with one or more intervening elements (either spatial or functional) present between the first and second elements if it is not explicitly described as "direct."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."

[0105] In the figures, the direction of an arrow, denoted by the arrowhead, generally demonstrates the flow of information (such as data or instructions) of interest for the illustration. For example, if element A and element B exchange different information, but the information transmitted from element A to element B is relevant for the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Furthermore, for the information sent from element A to element B, element B may send requests for or acknowledgments of receipt of the information to element A.

[0106] In this application, including the definitions below, the term "module" or the term "controller" may be replaced by the term "circuit". The term "module" may refer to, be part of, or contain: an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores the 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.

[0107] The module may include one or more interface circuits. According to some examples, the interface circuits may include wired or wireless interfaces connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules connected via interface circuits. For example, multiple modules may enable load balancing. According to another example, a server module (also known as a remote or cloud module) may perform some functionality on behalf of a client module.

[0108] The term code, as used above, may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. The term shared processor circuitry includes a single processor circuit that executes some or all of the code from multiple modules. The term group processor circuitry includes a processor circuit that, in combination with additional processor circuitry, executes some or all of the code from one or more modules. References to multiple processor circuits include multiple processor circuits on discrete dies, 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 refers to a single memory circuit that stores some or all of the code from multiple modules. The term group memory circuit refers to a memory circuit that, in combination with additional memories, stores some or all of the code from one or more modules.

[0109] The term memory circuit is a subset of the term computer-readable medium. As used herein, the term computer-readable medium does not include transient electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium can therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium include non-volatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

[0110] The devices and methods described in this application may be implemented partially or entirely by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in computer programs. The function blocks, flowchart components, and other elements described above serve as software specifications that can be translated into computer programs through the routine work of a trained technician or programmer.

[0111] The computer programs contain processor-executable instructions stored on at least one non-transitory, tangible, computer-readable medium. The computer programs may also contain or rely on stored data. The computer programs may include a basic input / output system (BIOS) that interacts with the hardware of the special-purpose computer, device drivers that interact with special-purpose devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0112] The computer programs may contain: (i) descriptive text to be parsed, such as: B. HTML (Hypertext Markup Language), XML (Extensible Markup Language) or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. By way of example only, the source code may be written using the syntax of languages ​​including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language, 5th Revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK and Python®.

Claims

[1] Insulation test system comprising: a plurality of conductive brushes arranged to brush insulated portions of a part to be tested; a plurality of voltage and current balancing circuits connected to the plurality of conductive brushes, each of the plurality of voltage and current balancing circuits configured to detect a short circuit between one or more bristles of the plurality of conductive brushes and an exposed conductive element of the part; and a control module configured to detect a defect in the insulating material of the part in response to the detected short circuit. [2] The insulation testing system of claim 1, further comprising a plurality of analog-to-digital converters configured to receive the analog signal outputs of the plurality of voltage and current balancing circuits. [3] The insulation testing system of claim 2, wherein the control module is configured to i) simultaneously monitor the digital outputs of the plurality of analog-to-digital converters and ii) simultaneously determine whether a defect exists at a location of a portion of each of the plurality of conductive brushes. [4] The insulation testing system of claim 1, wherein the control module is configured to i) track the position of each of the plurality of conductive brushes relative to the part as the part is moved relative to the plurality of conductive brushes, and ii) determine a location of the detected defect based on the tracked position of the corresponding one of the plurality of conductive brushes relative to the part. [5] The insulation testing system of claim 1, wherein the control module is configured to i) track the position of each of the plurality of conductive brushes relative to the part as the plurality of conductive brushes are moved relative to the part, and ii) determine a location of the detected defect based on the tracked position of the corresponding one of the plurality of conductive brushes relative to the part. [6] The insulation testing system of claim 1, further comprising a display, wherein the control module is configured to indicate the detection of the defect on the display. [7] The insulation testing system of claim 1, further comprising an acoustic device, wherein the control module is configured to indicate detection of the defect via the acoustic device. [8] The insulation testing system of claim 1, wherein each of the plurality of voltage and current balancing circuits comprises a pair of resistors and a capacitor. [9] The insulation testing system of claim 1, further comprising a plurality of analog-to-digital converters, wherein: each of the plurality of analog-to-digital converters comprises a set of input terminals; and each of the plurality of voltage and current balancing circuits comprises a pair of resistors and a respective capacitor connected in series between two terminals of the set of input terminals of the corresponding one of the plurality of analog-to-digital converters. [10] Insulation testing system according to claim 9, wherein: the pair of resistors of each of the plurality of voltage and current balancing circuits comprises a first resistor and a second resistor; the set of input terminals of each of the plurality of analog-to-digital converters comprises a positive terminal, a negative terminal, and a common terminal; the first resistor of each pair of resistors comprises i) a first end connected to a respective one of the positive terminals and to a respective one of the plurality of conductive brushes, and ii) a second end connected to a first end of the respective capacitor; and the second resistor comprises i) a first end connected to a respective one of the common terminals, and ii) a second end connected to a second end of the respective capacitor and to the part.

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