DESC:METHOD AND SYSTEM FOR INSULATION MEASUREMENT
CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority from Indian Provisional Patent Application No. 202421024550 filed on 27/03/2024, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
The present disclosure generally relates to an electric drive. Particularly, the present disclosure relates to a system for offline insulation monitoring on an alternating current AC side of an electric drive. Furthermore, the present disclosure relates to a method of offline insulation monitoring on an alternating current AC side of an electric drive.
BACKGROUND
The electric vehicle (EV) market is rapidly expanding, driven by advancements in battery technology, government incentives, and increasing environmental concerns. The Auto-manufacturers re investing heavily in EV infrastructure, including fast-charging networks and improved energy efficiency. Additionally, the solid-state batteries and high-efficiency powertrains are emerging as key innovations for future EVs.
Recently, the motor drive system in electric vehicles has evolved with advancements in power electronics, control algorithms, and efficiency optimization. The modern electric and hybrid vehicles utilize high-efficiency inverters and advanced motor designs like PMSM and induction motors. Also, the emerging trends include SiC and GaN-based inverters for reduced losses and higher power density. However, with increasing usage of motor drive in vehicles, the insulation problems in the motor drive arises. The insulation problems in the motor drive occur due to factors such as electrical stress, thermal degradation, mechanical vibrations, and environmental conditions like moisture or contaminants. Over time, high-voltage stress may cause insulation breakdown, leading to leakage currents and reduced system efficiency. Also, excessive heat from prolonged operation accelerates material aging, weakening insulation properties. Furthermore, the mechanical shocks and continuous vibrations may create microcracks in insulating layers, increasing the risk of failure. Additionally, dust, humidity, and chemical exposure can degrade insulation surfaces, leading to unintended short circuits or safety hazards.
Traditionally, the isolation in the motor drives of electric vehicles traditionally monitored using resistance-based measurement techniques, voltage monitoring methods, and insulation resistance testers. These methods primarily relied on measuring the insulation resistance between the high-voltage (HV) system and the vehicle chassis to detect any potential faults or degradation in isolation. One of the common technique is resistance measurement method, where a high-value resistor is connected between the HV bus and the chassis ground. By applying a known voltage and measuring the leakage current, the insulation resistance is calculated. If the resistance dropped below a predefined threshold, an isolation fault is detected. However, the method has significant drawbacks. Firstly, these method required additional passive components that added to the system complexity and cost. Secondly, the method may not detect dynamic isolation failures, such as insulation breakdown occurring due to transient voltage spikes or mechanical stress over time. Moreover, during operation, insulation degradation is often gradual and not easily captured by periodic resistance measurements, leading to potential undetected faults. Another conventional approach involved voltage-based monitoring, where the voltage difference between the HV system and the chassis ground is continuously observed. Any unexpected fluctuations in the voltage difference may be indicate a loss of isolation. While the method is relatively straightforward, but the method suffered from low sensitivity to minor faults, making the method ineffective in detecting early-stage insulation degradation. Additionally, the method prone to false positives due to external noise, temperature variations, or minor fluctuations in the high-voltage system, leading to unnecessary warnings or system shutdowns. Moreover, a more manual method is often used which is the insulation resistance test using a megohmmeter, where a high DC voltage (e.g., 500V to 1000V) is applied to the motor drive circuit while the vehicle is off, and the resulting leakage current is measured to determine insulation integrity. This method is highly effective in detecting severe insulation breakdowns but not impractical for real-time monitoring, as the method required the vehicle to be taken offline for testing. Moreover, the method may be only detecting the insulation failures that had already occurred and is not effective in predicting insulation degradation over time.
Therefore, there is a need to provide an improved technique for isolation detection in a motor drive of an electric vehicle to overcome one or more problems associated as set forth above.
SUMMARY
An object of the present disclosure is to provide a system for offline insulation monitoring on an alternating current AC side of an electric drive.
Another object of the present disclosure is to provide a method of offline insulation monitoring on an alternating current AC side of an electric drive.
In accordance with first aspect of the present disclosure, there is provided a system for offline insulation monitoring on an alternating current AC side of an electric drive. The system comprises a plurality of switches, wherein a respective switch of the plurality of switches is connected between a respective phase of a multi-phase AC system and a chassis ground, a plurality of series resistances, wherein a respective series resistance is connected in series with the respective switch of the plurality of switches, a voltage measurement circuit configured to measure voltage across each of the series resistances during different switching states and a controller. The controller configured to control the plurality of switches to turn on and off in a predetermined sequence, receive voltage measurements from the voltage measurement circuit corresponding to each switching state and determine an insulation health status of each phase of the multi-phase AC system based on a combination of the received voltage measurements.
The present disclosure provides the system for offline insulation monitoring on an alternating current AC side of an electric drive. The system as disclosed by present disclosure is advantageous in terms of providing an enhanced safety, reliability, and efficiency in the system. Beneficially, the system enables precise detection of insulation health in each phase without interfering with normal operation. Beneficially, the system ensures that insulation issues are identified during non-operational states, thereby reducing the risk of unexpected failures during active operation. Furthermore, the system enhances the fault localization which allows for targeted maintenance and minimizing downtime. Beneficially, the system ensures a robust and energy-efficient approach to insulation monitoring without the need for external high-voltage sources which makes the system cost-effective and easily integrable into existing electric drive architectures. Additionally, the system enables the proactive fault detection, thereby reducing the risk of catastrophic insulation failures. Additionally, the system improves user awareness which ensures the timely intervention when insulation degradation surpasses a critical threshold.
In accordance with second aspect of the present disclosure, there is provided a method of offline insulation monitoring on an alternating current AC side of an electric drive. The method comprises connecting a plurality of switches with series resistances between each phase of a multi-phase AC system and a chassis ground, controlling the plurality of switches to turn on and off in a predetermined sequence, measuring voltage across each of the series resistances during different switching states of the predetermined sequence, analyzing a combination of the measured voltages and determining an insulation health status of each phase of the multi-phase AC system based on the analysis of the combination of measured voltages.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 illustrates a block diagram of a system for offline insulation monitoring on an alternating current AC side of an electric drive, in accordance with an aspect of the present disclosure.
FIG. 2 illustrates a flow chart of a method of offline insulation monitoring on an alternating current AC side of an electric drive, in accordance with another aspect of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practising the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a system for offline insulation monitoring on an alternating current AC side of an electric drive and is not intended to represent the only forms that may be developed or utilised. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimised to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings and which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms “electric vehicle”, “EV”, and “EVs” are used interchangeably and refer to any vehicle having stored electrical energy, including the vehicle capable of being charged from an external electrical power source. This may include vehicles having batteries which are exclusively charged from an external power source, as well as hybrid-vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the ‘electric vehicle’ as used herein includes electric two-wheeler, electric three-wheeler, electric four-wheeler, electric pickup trucks, electric trucks and so forth.
As used herein, the term “offline insulation monitoring” refers to a method or system for assessing the insulation integrity of an electrical system when the system is in a non-operational state, means the system not actively supplying power or performing the primary function. The insulation monitoring is performed without requiring external high voltage sources and typically involves controlled voltage application, resistance measurement, or other diagnostic techniques to detect insulation degradation, leakage paths, or potential faults.
As used herein, the terms “electric drive” refers to system that converts electrical energy into mechanical motion using one or more electric machines, typically comprising power electronics, control circuitry, and associated components to regulate speed, torque, and operational parameters. The electric drive may include an electric motor, an inverter or converter for power modulation, a control unit for operation management, and optionally, sensors for feedback control.
As used herein, the term “communicably coupled” refers to a bi-directional connection between the various components of the system. The bi-directional connection between the various components of the system enables exchange of data between two or more components of the system. Similarly, bi-directional connection between the system and other elements/modules enables exchange of data between system and the other elements/modules.
As used herein, the term “plurality of switches” and “switches” are used interchangeably and refer to two or more electrically controllable switching devices that are configured to selectively establish or interrupt electrical connections within a system. The switches may be implemented using various technologies, including but not limited to semiconductor switches (e.g., MOSFETs, IGBTs, thyristors) or mechanical switches (e.g., relays, contactors), depending on the application requirements. The switches may operate independently or in coordination under the control of a controller to achieve a specific function, such as insulation monitoring, fault detection, or power regulation.
As used herein, the term “multi-phase AC system” refers to electrical system configured to generate, distribute, or utilize alternating current (AC) in multiple phases, wherein each phase consists of a distinct AC voltage waveform that is phase-shifted relative to the other phases. The system typically includes multiple conductors carrying these phase-shifted voltages and is used to enhance power efficiency, reduce electrical losses, and improve torque characteristics in electric drive applications.
As used herein, the term “chassis ground” refers to a conductive reference point in an electrical system, typically formed by the metallic chassis or frame of a device, vehicle, or equipment, which serves as a common return path for electrical currents and a grounding point for safety. The chassis ground provides an electrical connection to the vehicle or equipment frame, enabling fault detection, insulation monitoring, and protection against electrical hazards by preventing unintended voltage buildup.
As used herein, the term “plurality of series resistances” and “series resistances” are used interchangeably and refer to two or more electrical resistances, each configured in series with a corresponding switch of a plurality of switches, wherein each series resistance is connected between a respective phase of a multi-phase alternating current (AC) system and a chassis ground, and wherein the resistances facilitate voltage measurement for insulation monitoring.
As used herein, the term “voltage measurement circuit” refers to an electrical circuit configured to measure voltage across one or more components in a system and provide corresponding voltage data to a controller or processing unit. The circuit typically comprises voltage sensing elements, such as resistors, differential amplifiers, analog-to-digital converters (ADCs), or other signal conditioning components, to accurately capture voltage levels while minimizing noise and interference.
As used herein, the term “switching states” refers to a specific condition or configuration of one or more switches within a system at a given point in time, determined by their operational status (e.g., ON or OFF). The switching state defines the electrical connectivity between components, influencing circuit behavior, voltage distribution, and current flow. In a system with multiple switches, different switching states result from controlled activation or deactivation sequences, enabling functions such as measurement, fault detection, or signal processing.
As used herein, the term “controller” refers to a processing unit, microcontroller, processor, application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or any combination thereof, configured to execute instructions stored in a memory to perform a specific set of operations. The controller is responsible for processing input signals, executing control algorithms, and generating output signals to regulate the operation of one or more components within a system. The controller may communicate with various sensors, actuators, and peripheral devices via wired or wireless communication interfaces to enable automated control, monitoring, and decision-making functions.
As used herein, the term “predetermined sequence” refers to a predefined and structured order of operations or steps that are executed in a specific manner based on a set of predefined rules or logic. This sequence is typically established before execution and does not change dynamically based on external inputs during its operation.
As used herein, the term “insulation health status” refers to a condition assessment of the electrical insulation in a system, indicating its ability to effectively isolate electrical components and prevent unintended leakage currents to ground or between conductive elements. It is determined based on measured electrical parameters, such as leakage current, resistance, or voltage deviations, and is used to detect insulation degradation, faults, or potential failures. The insulation health status may be classified into different levels, such as normal, degraded, or faulty, based on predefined thresholds, ensuring proactive maintenance and system reliability.
As used herein, the term “three-phase system” refers to a power distribution system comprising three alternating current (AC) voltage waveforms that are phase-shifted by 120 degrees relative to each other, wherein each phase provides electrical power to a load. The system is configured to deliver balanced power with improved efficiency, reduced conductor material requirements, and lower ripple in power conversion applications.
As used herein, the term “semiconductor switches” refers to an electronic switching device composed of semiconductor materials, configured to control the conduction of electrical current between terminals based on an applied control signal. Such semiconductor switches may transition between conducting and non-conducting states, enabling or interrupting current flow in a circuit.
As used herein, the term “leakage” refers to an unintended flow of electric current from a designated conductive path to another conductive element, such as a chassis ground or surrounding environment, due to insulation degradation, dielectric failure, or unintended conductive paths. The leakage may result in energy losses, safety hazards, or performance degradation in an electrical or electronic system.
As used herein, the term “electric drive train unit” refers to an integrated assembly of components responsible for converting electrical energy into mechanical motion to propel a vehicle or machinery. The electric drive train unit typically includes an electric motor, power electronics (such as an inverter or motor controller), a transmission system, and associated driveline components that transmit torque to the wheels or load. The electric drive train unit may also encompass additional elements such as insulation monitoring systems, cooling mechanisms, and regenerative braking systems to enhance efficiency and safety.
As used herein, the term "offline state" refers to a condition in which the electric drive or system is not actively operating under its normal load or functional mode. The offline state means the drive is not supplying power to the motor or executing its primary operational tasks but remains in a state where certain monitoring, diagnostic, or maintenance functions can still be performed. The offline state may occur when the system is powered down, in standby mode, or during scheduled maintenance periods.
As used herein, the term “display unit” refers to a hardware or electronic component configured to visually present information related to system operation, diagnostics, or status. The display unit may include, but is not limited to, liquid crystal displays (LCDs), light-emitting diode (LED) displays, organic light-emitting diode (OLED) displays, touchscreens, graphical user interfaces (GUIs), indicator lights, or any other visual output mechanism. The display unit may be integrated into a control panel, a dashboard, a handheld device, or a remote monitoring system and can communicate with a controller or processing unit to provide real-time or stored data regarding system parameters, alerts, or user notifications.
As used herein, the term “series of switching states” refers to a predefined sequence of discrete operational conditions in which one or more switches transition between different states, such as ON and OFF, according to a predetermined control logic. Each switching state corresponds to a unique configuration of switch activations, allowing for controlled electrical measurements or operations within a system.
As used herein, the term “non-operational state” refers to a condition in which the electric drive system is not actively performing the primary function of converting the electrical energy into mechanical motion. The non-operational state includes scenarios where the system is powered off, in standby mode, undergoing maintenance, or temporarily inactive without delivering torque or rotational motion. The non-operational state may also encompass instances where the system is de-energized or isolated from the main power supply while still allowing certain monitoring or diagnostic functions to be performed.
As used herein, the term “alert” refers to a notification or indication generated by a system or method in response to a detected condition, such as a fault, anomaly, or threshold breach, to prompt corrective action or inform a user or control system.
Figure 1 in accordance with an embodiment describes a system 100 for offline insulation monitoring on an alternating current AC side of an electric drive. The system 100 comprises a plurality of switches 102, wherein a respective switch of the plurality of switches 102 is connected between a respective phase of a multi-phase AC system 104 and a chassis ground, a plurality of series resistances 106, wherein a respective series resistance is connected in series with the respective switch of the plurality of switches 102, a voltage measurement circuit 108 configured to measure voltage across each of the series resistances during different switching states and a controller 110 configured to control the plurality of switches 102 to turn on and off in a predetermined sequence, receive voltage measurements from the voltage measurement circuit 108 corresponding to each switching state and determine an insulation health status of each phase of the multi-phase AC system 104 based on a combination of the received voltage measurements.
The present disclosure discloses the system 100 for offline insulation monitoring on the alternating current AC side of the electric drive. The system 100 and method 200 as disclosed by present disclosure is advantageous in terms of providing an enhanced safety, reliability, and efficiency in the electric drive applications. Beneficially, the ability of the system 100 to detect insulation degradation or leakage faults without requiring external high-voltage sources significantly makes the system 100 a self-sufficient solution that reduces complexity and cost. By employing the plurality of switches 102 and series resistances in conjunction with the voltage measurement circuit 108, the system 100 enables phase-wise insulation monitoring which allows precise identification of which phase has deteriorated insulation. Beneficially, the targeted fault detection improves maintenance efficiency and reduces downtime by enabling proactive interventions before insulation failures lead to severe electrical faults. Furthermore, the execution of insulation monitoring in the offline state, ensures the assessment does not interfere with normal drive operations which enhances the safety by preventing inadvertent power disruptions or transient effects on the drive system. Beneficially, the use of the predetermined switching sequence provides a structured and repeatable method for evaluating insulation health, thereby improves the diagnostic accuracy. Additionally, by comparing measured voltages to the predefined thresholds, the system 100 may be able to detect even minor insulation degradation trends, thereby allows predictive maintenance strategies to be implemented. Furthermore, the integration of a display unit 112 for insulation health indication further enhances user accessibility by providing real-time diagnostics, thereby enables informed decision-making. Furthermore, the use of semiconductor switches ensures the high-speed switching capability leads to more efficient and precise measurement cycles. Additionally, the ability of the system 100 to function without disrupting the electric drive train unit ensures that insulation monitoring is to be performed without necessitating complex disassembly or system modifications. Furthermore, the capability to generate the alerts when insulation degradation surpasses the predetermined threshold is essential safety feature which ensures timely action, thereby reduces the risk of electrical failures, short circuits, or hazardous conditions such as electric shock or fire hazards.
In an embodiment, the multi-phase AC system 104 comprises a three-phase system. Each phase of the three-phase system may be electrically connected to the insulation monitoring circuit. The system 100 may be configured to assess the insulation condition of each phase independently which ensures the precise detection of insulation degradation or leakage faults.
In an embodiment, the plurality of switches 102 comprises a semiconductor switches. The semiconductor switches facilitate the controlled connection and disconnection of each phase to the chassis ground through series resistances. The use of semiconductor switching components enhances reliability by minimizing mechanical wear, reducing switching time, and improving overall system accuracy in voltage measurement.
In an embodiment, the controller 110 is configured to identify which phase has a leakage to the chassis ground based on the combination of received voltage measurements. The identification of the leakage may be performed by analyzing a combination of voltage measurements received from the voltage measurement circuit 108 corresponding to different switching states of the plurality of switches 102. By systematically controlling the switching sequence and evaluating the resulting voltage variations across the series resistances, the controller 110 maya be isolate the phase exhibiting abnormal leakage characteristics. Beneficially, the leakage detection with the help of controller 110 enables the targeted fault diagnosis, thereby allowing the maintenance actions to be taken proactively before insulation failure leads to critical system issues.
In an embodiment, the system 100 is configured to monitor insulation in an electric drive train unit. Furthermore, the controller 110 is configured to execute the predetermined sequence during an offline state of the electric drive. Furthermore, the system 100 is communicably coupled with a display unit 112 to provide an indication of the insulation health status. The controller 110 manages the sequential activation of the plurality of switches 102 to individually assess each phase of the multi-phase AC system 104 without interfering with normal operation. By analyzing the voltage measurements obtained from the voltage measurement circuit 108, the controller 110 determines the insulation health status of each phase, identifying potential leakage paths to the chassis ground. The system 100 may also be communicably coupled to a display unit 112 for real-time indication of insulation status, facilitating maintenance and safety interventions. Beneficially, by operating in the offline state, the system 100 avoids the disruptions to the electric drive, thereby enhances the overall safety and operational efficiency. Moreover, the system 100 ensures reliable insulation monitoring by leveraging controlled switching and measurement techniques which allows the early detection of insulation degradation or leakage faults.
In an embodiment, the system 100 for offline insulation monitoring on the alternating current AC side of the electric drive. The system 100 comprises the plurality of switches 102, wherein the respective switch of the plurality of switches 102 is connected between the respective phase of a multi-phase AC system 104 and the chassis ground, the plurality of series resistances 106, wherein the respective series resistance is connected in series with the respective switch of the plurality of switches 102, the voltage measurement circuit 108 configured to measure voltage across each of the series resistances during different switching states and the controller 110 configured to control the plurality of switches to turn on and off in the predetermined sequence, receive voltage measurements from the voltage measurement circuit corresponding to each switching state and determine the insulation health status of each phase of the multi-phase AC system 104 based on the combination of the received voltage measurements. Furthermore, the multi-phase AC system 104 comprises the three-phase system. Furthermore, the plurality of switches 102 comprises the semiconductor switches. Furthermore, the controller 110 is configured to identify which phase has the leakage to the chassis ground based on the combination of received voltage measurements. Furthermore, the system 100 is configured to monitor insulation in the electric drive train unit. Furthermore, the controller 110 is configured to execute the predetermined sequence during the offline state of the electric drive. Furthermore, the system 100 is communicably coupled with the display unit 112 to provide the indication of the insulation health status.
Figure 2 describes a method 200 of offline insulation monitoring on an alternating current AC side of an electric drive. The method 200 starts at step 202 and completes at step 210. At step 202, the method 200 comprises connecting a plurality of switches 102 with series resistances between each phase of a multi-phase AC system 104 and a chassis ground. At step 204, the method 200 comprises controlling the plurality of switches 102 to turn on and off in a predetermined sequence. At step 206, the method 200 comprises measuring voltage across each of the series resistances during different switching states of the predetermined sequence. At step 208, the method 200 comprises analyzing a combination of the measured voltages. At step 210, the method 200 comprises determining an insulation health status of each phase of the multi-phase AC system 104 based on the analysis of the combination of measured voltages.
In an embodiment, determining the insulation health status comprises identifying a leakage to the chassis ground from each phase of the multi-phase AC system 104.
In an embodiment, the predetermined sequence comprises a series of switching states in which each switch is activated individually.
In an embodiment, the method 200 comprises comparing the measured voltages to predetermined threshold values to detect insulation degradation.
In an embodiment, the method 200 is performed during a non-operational state of the electric drive.
In an embodiment, the method 200 comprises generating an alert when insulation degradation is detected beyond a predetermined threshold.
In an embodiment, the multi-phase AC system 104 is part of an electric motor drive system.
In an embodiment, the method 200 provides insulation monitoring without requiring external high-voltage sources.
It would be appreciated that all the explanations and embodiments of the portable device 100 also applies mutatis-mutandis to the method 200.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combination of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non- exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
,CLAIMS:WE CLAIM:
1. A system (100) for offline insulation monitoring on an alternating current AC side of an electric drive, wherein the system (100) comprises:
- a plurality of switches (102), wherein a respective switch of the plurality of switches (102) is connected between a respective phase of a multi-phase AC system (104) and a chassis ground;
- a plurality of series resistances (106), wherein a respective series resistance is connected in series with the respective switch of the plurality of switches (102);
- a voltage measurement circuit (108) configured to measure voltage across each of the series resistances during different switching states; and
- a controller (110) configured to:
- control the plurality of switches (102) to turn on and off in a predetermined sequence;
- receive voltage measurements from the voltage measurement circuit (108) corresponding to each switching state; and
- determine an insulation health status of each phase of the multi-phase AC system (104) based on a combination of the received voltage measurements.
2. The system (100) as claimed in claim 1, wherein the multi-phase AC system (104) comprises a three-phase system.
3. The system (100) as claimed in claim 1, wherein the plurality of switches (102) comprises a semiconductor switches.
4. The system (100) as claimed in claim 1, wherein the controller (110) is configured to identify which phase has a leakage to the chassis ground based on the combination of received voltage measurements.
5. The system (100) as claimed in claim 1, wherein the system (100) is configured to monitor insulation in an electric drive train unit.
6. The system (100) as claimed in claim 1, wherein the controller (110) is configured to execute the predetermined sequence during an offline state of the electric drive.
7. The system (100) as claimed in claim 1, wherein the system (100) is communicably coupled with a display unit (112) to provide an indication of the insulation health status.
8. A method (200) of offline insulation monitoring on an alternating current AC side of an electric drive, wherein the method (200) comprises:
- connecting a plurality of switches (102) with series resistances between each phase of a multi-phase AC system (104) and a chassis ground;
- controlling the plurality of switches (102) to turn on and off in a predetermined sequence;
- measuring voltage across each of the series resistances during different switching states of the predetermined sequence;
- analyzing a combination of the measured voltages; and
- determining an insulation health status of each phase of the multi-phase AC system (104) based on the analysis of the combination of measured voltages.
9. The method (200) as claimed in claim 8, wherein determining the insulation health status comprises identifying a leakage to the chassis ground from each phase of the multi-phase AC system (104).
10. The method (200) as claimed in claim 8, wherein the predetermined sequence comprises a series of switching states in which each switch is activated individually.
11. The method (200) as claimed in claim 8, wherein the method (200) comprises comparing the measured voltages to predetermined threshold values to detect insulation degradation.
12. The method (200) as claimed in claim 8, wherein the method (200) is performed during a non-operational state of the electric drive.
13. The method (200) as claimed in claim 8, wherein the method (200) comprises generating an alert when insulation degradation is detected beyond a predetermined threshold.
14. The method (200) as claimed in claim 8, wherein the multi-phase AC system (104) is part of an electric motor drive system.
15. The method (200) as claimed in claim 8, wherein the method (200) provides insulation monitoring without requiring external high-voltage sources.