CN-122029438-A - System and method for monitoring insulation resistance of motor stator

Abstract

A method and system for monitoring Insulation Resistance (IR) of an electric machine, the system comprising a bridge circuit arrangement. The voltage across the bridge circuit arrangement is detected. IR is calculated as the resistance in the bridge circuit arrangement associated with the detected voltage.

Inventors

• JOHN PHILIP
• A. Shantama
• K .kai

Assignees

• 盖瑞特动力科技(上海)有限公司
• 盖瑞特动力科技(武汉)有限公司

Dates

Publication Date

20260512

Application Date

20240724

Priority Date

20230807

Claims (20)

1. 1. A method of monitoring Insulation Resistance (IR) of an electric machine, the method comprising: Providing a bridge circuit arrangement having a power supply, a first leg, a second leg, a third leg and a fourth leg, wherein the first leg is electrically connected to the motor and has an unknown first resistance (R1) corresponding to the IR of the motor, the second leg has a second resistance (R2), the third leg has a predetermined third resistance (R3), the fourth leg has a predetermined fourth resistance (R4), the first leg and the second leg are electrically connected at a first node (X) to collectively define a first side of the bridge circuit arrangement, the third leg and the fourth leg are electrically connected at a second node (Y) to collectively define a second side of the bridge circuit arrangement, the bridge circuit arrangement comprises a bridge electrically connected to the first node and the second node to operatively connect the first side and the second side of the bridge circuit arrangement, the bridge comprises a sensor configured to detect a voltage vx between the first node and the second node; Providing a control system operatively connected to the bridge circuit, the control system including a processor; Detecting a voltage Vxy; IR is calculated by the processor as a first resistance (R1) associated with the detected voltage Vxy.
2. 2. The method of claim 1, wherein detecting the voltage Vxy includes detecting that the voltage Vxy is approximately zero to balance the first side and the second side of the bridge circuit arrangement, and Wherein calculating IR comprises calculating IR as the first resistance (R1) by the processor when the voltage Vxy is detected to be approximately zero, wherein the first resistance (R1) is equal to the product of the second resistance (R2) and the third resistance (R3) divided by the fourth resistance (R4).
3. 3. The method of claim 2, wherein the second leg has a variable second resistance (R2), and further comprising selectively adjusting the second resistance R2 to approximate a voltage Vxy of zero.
4. 4. The method of claim 3 further comprising providing a memory device and further comprising storing in the memory device a selectively adjusted second resistance R2 that approximates voltage Vxy to zero.
5. 5. The method of claim 4, further comprising saving the calculated IR associated with the selectively adjusted second resistance R2 in the memory device.
6. 6. The method of any of the preceding claims, wherein the third leg has a first lead for a first winding of the electric machine and a second lead for a second winding of the electric machine; Further comprising providing a switch having a first position in which the first lead is included in the third leg and a second position in which the second lead is included in the third leg, and Further comprising switching, by the processor, the switch between the first position and the second position.
7. 7. The method of any of the preceding claims, further comprising determining, by the processor, whether the calculated IR is below a predetermined threshold.
8. 8. The method of claim 7, further comprising outputting a user output as a result of the processor determining that IR is below the predetermined threshold.
9. 9. The method of claim 7 or 8, further comprising outputting a user output as a result of the processor determining that IR is below the predetermined threshold.
10. 10. The method of any of the preceding claims, characterized in that said second leg has a predetermined fixed second resistance (R2); wherein detecting the voltage Vxy includes detecting a Root Mean Square (RMS) voltage Vxy; also includes detecting a root mean square voltage V of a phase voltage output of an inverter powering the bridge circuit arrangement, and Wherein calculating IR comprises calculating IR by the processor according to the following formula: IR = 。
11. 11. A system for monitoring Insulation Resistance (IR) of an electric machine, the system comprising: A bridge circuit arrangement having a power supply, a first leg, a second leg, a third leg and a fourth leg, wherein the first leg is electrically connected to the motor and has an unknown first resistance (R1) corresponding to the IR of the motor, the second leg has a second resistance (R2), the third leg has a predetermined third resistance (R3), the fourth leg has a predetermined fourth resistance (R4), the first leg and the second leg are electrically connected at a first node (X) to collectively define a first side of the bridge circuit arrangement, the third leg and the fourth leg are electrically connected at a second node (Y) to collectively define a second side of the bridge circuit arrangement, the bridge circuit arrangement comprises a bridge electrically connected to the first node and the second node to operatively connect the first side and the second side of the bridge circuit arrangement, the bridge comprises a sensor configured to detect a voltage vx between the first node and the second node; A control system operatively connected to the bridge circuit, the control system comprising a processor; the processor is configured to detect a voltage Vxy; The processor is configured to calculate IR as a first resistance (R1) associated with the detected voltage Vxy.
12. 12. The method of claim 11, wherein the processor is configured to detect a voltage Vxy of approximately zero, thereby balancing the first side and the second side of the bridge circuit arrangement, and Wherein the processor is configured to calculate IR as the first resistance (R1) when the voltage Vxy is detected to be approximately zero, wherein the first resistance (R1) is equal to the product of the second resistance (R2) and the third resistance (R3) divided by the fourth resistance (R4).
13. 13. The system of claim 12, wherein the second leg has a variable second resistance (R2), and wherein the processor is configured to selectively adjust the second resistance R2 to approximate a voltage Vxy of zero.
14. 14. The system of claim 13, further comprising a memory device configured to hold the selectively adjusted second resistance R2 that approximates the voltage Vxy to zero.
15. 15. The system of claim 14, wherein the memory device is configured to hold the calculated IR associated with the selectively adjusted second resistance R2.
16. 16. The system of any one of claims 11, 12, 13, 14, 15, or 16, wherein the third leg has a first lead for a first winding of the motor and a second lead for a second winding of the motor; Also included is a switch having a first position in which the first lead is included in the third leg and a second position in which the second lead is included in the third leg, and Wherein the processor is configured to change the switch between the first position and the second position.
17. 17. The system of any of claims 11, 12, 13, 14, 15, 16, or 17, wherein the processor is configured to determine whether the calculated IR is below a predetermined threshold, optionally wherein the system further comprises an output device having a user interface configured to output a user output as a result of the processor determining that the IR is below the predetermined threshold.
18. 18. The system of any one of claims 11 to 17, wherein the second leg has a predetermined fixed second resistance (R2); Wherein the processor is configured to detect the voltage Vxy as a Root Mean Square (RMS) of the voltage Vxy; Wherein the processor is configured to detect an RMS voltage V of a phase voltage output of an inverter powering the bridge circuit arrangement, and Wherein the processor is configured to calculate IR according to the following formula IR = 。
19. 19. A method for monitoring Insulation Resistance (IR) of an electrical machine having an electrical insulator, the method comprising: Providing a bridge circuit arrangement having a power supply, a first leg, a second leg, a third leg and a fourth leg, wherein the first leg is electrically connected to a motor and has an unknown first resistance (R1) corresponding to IR of the electrical insulator, the second leg has a second resistance (R2), the third leg has a predetermined third resistance (R3), the fourth leg has a predetermined fourth resistance (R4), the first leg and the second leg are electrically connected at a first node (X) to collectively define a first side of the bridge circuit arrangement, the third leg and the fourth leg are electrically connected at a second node (Y) to collectively define a second side of the bridge circuit arrangement, the bridge circuit arrangement comprises a bridge electrically connected to the first node and the second node to operatively connect the first side and the second side of the bridge circuit arrangement, the bridge comprises a sensor configured to detect a voltage between the first node and the second node; Providing a control system operatively connected to the bridge circuit, the control system including a processor; Selectively adjusting, by the processor, the second resistance (R2) to a selectively adjusted value at which the sensor detects a voltage of approximately zero to balance a first side and a second side of the bridge circuit arrangement; Calculating, by the processor, IR as the product of the selectively adjusted second resistance (R2) and the third resistance (R3) divided by the fourth resistance (R4) (ir=r1= (r2×r3)/R4); Determining, by the processor, whether the calculated IR is below a predetermined threshold, and A user output is output as the processor determines that IR is below the predetermined threshold.
20. 20. The method of claim 19, wherein the electrical insulator provides electrical insulation for a stator of the motor, the motor further comprising a rotor supported on a shaft of the motor, the shaft configured to transmit rotational power during an operational state of the motor, and Wherein selectively adjusting the second resistance (R2), calculating the IR, and determining whether the calculated IR is below a predetermined threshold is performed concurrently with an operating state of the motor.

Description

System and method for monitoring insulation resistance of motor stator Cross Reference to Related Applications The present application claims priority from indian provisional patent application No. 202311072694 filed on day 10, 25 of 2023 and indian provisional patent application No. 202311052976 filed on day 8, 7 of 2023, the disclosures of which are incorporated herein by reference in their entirety. Technical Field The present technology relates generally to electric machines and, more particularly, to a system and method for insulation resistance monitoring of an electric machine stator. Background Electrical machines (e-machines), such as electric motors and generators, typically include an electrical insulator (i.e., an electrically insulating feature) for maintaining proper operation, protecting components, users, and the like. For example, the motor may include a stator with one or more layers or coatings of electrically insulating material (i.e., insulation, insulator material) applied thereto. For example, an insulator may be included between the stator windings and the outer housing of the motor to provide electrical insulation (i.e., insulation resistance "IR") therebetween. There may also be a gap between the windings and the outer housing and the air in this gap may also contribute to the IR of the motor. Preferably, the IR is higher and remains at a higher level over time due to motor usage. IR monitoring of the motor is required. However, testing and monitoring IR of the motor can be difficult, inconvenient, and/or time consuming. Such detection may require a longer time to deactivate the motor, which is disadvantageous. Furthermore, such monitoring may require expensive instrumentation. Accordingly, there is a need to provide a convenient and low cost system and method for monitoring the IR of an electric machine. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background. Disclosure of Invention A method for monitoring Insulation Resistance (IR) of an electric machine is disclosed. The method comprises providing a bridge circuit arrangement having a power supply, a first leg electrically connected to the motor and having an unknown first resistance (R1) corresponding to the IR of the motor, a second leg having a second resistance (R2), a third leg having a predetermined third resistance (R3), and a fourth leg having a predetermined fourth resistance (R4). The first leg and the second leg are electrically connected at a first node (X) to together define a first side of the bridge circuit arrangement, and the third leg and the fourth leg are electrically connected at a second node (Y) to together define a second side of the bridge circuit arrangement. The bridge circuit arrangement includes a bridge electrically connected to the first node and the second node to operatively connect the first side and the second side of the bridge circuit arrangement. The bridge includes a sensor configured to detect a voltage Vxy between a first node and a second node. The method further includes providing a control system operatively connected to the bridge circuit. The control system includes a processor. The method further includes detecting a voltage Vxy. Further, the method includes calculating, by the processor, IR as a first resistance (R1) associated with the detected voltage Vxy. Furthermore, a system for monitoring Insulation Resistance (IR) of an electric machine is disclosed. The system comprises a bridge circuit arrangement having a power supply, a first leg electrically connected to the motor and having an unknown first resistance (R1) corresponding to the IR of the motor, a second leg having a second resistance (R2), a third leg having a predetermined third resistance (R3), and a fourth leg having a predetermined fourth resistance (R4). The first leg and the second leg are electrically connected at a first node (X) to together define a first side of the bridge circuit arrangement, and the third leg and the fourth leg are electrically connected at a second node (Y) to together define a second side of the bridge circuit arrangement. The bridge circuit arrangement includes a bridge electrically connected to the first node and the second node to operatively connect the first side and the second side of the bridge circuit arrangement. The bridge includes a sensor configured to detect a voltage Vxy between a first node and a second node. In addition, the system includes a control system operatively connected to the bridge circuit. The control system includes a processor. The processor is configured to detect a voltage Vxy. The processor is configured to calculate IR as a first resistance (R1) associated with the detected voltage Vxy. Furthermore, a method for monitoring an Insulation Resistance (IR) of an electrical machine having an electrical