Insulation deterioration determination device

Abstract

To provide an insulation deterioration determination device capable of determining deterioration of an insulation part in a motor, that is caused by a partial discharge.SOLUTION: According to an insulation deterioration determination device comprising: a power control unit provided with a plurality of switching elements; and a motor provided with an insulation part including inter-coil spaces, that is driven by applying a voltage to a plurality of coils by controlling the insulation part the power control unit, the device determines a motor operation point based on torque and the number of revolutions of the motor at each predetermined period (in step S3); determines whether or not the motor operation point is a partial discharge generating operation point at which a partial discharge is generated by a surge voltage due to switch-controlling of the switch elements (in step S4); accumulates the number of times when the motor operation point is the partial discharge generating operation point (in step S5); and determines that the insulation part is insulation-deteriorated, when the accumulated number of times when the motor operation point is the partial discharge generating operation point is the predetermined number of times or more (in step S7).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an apparatus for determining deterioration due to partial discharge in an insulating portion provided in a motor or a generator, such as a coating material for a coil.

Background Art

[0002] Patent Document 1 describes a control device for a vehicle including a motor that drives a pair of front wheels and a motor that drives a pair of rear wheels. This control device is provided with a map that determines an operating point of the motor at which a surge voltage becomes a voltage that causes partial discharge. When the operating point of each motor becomes an operating point at which partial discharge occurs, the output is increased so that the operating point of one motor becomes an operating point at which partial discharge does not occur, and the output is decreased so that the operating point of the other motor becomes an operating point at which partial discharge does not occur, thereby suppressing the occurrence of partial discharge by driving each motor while maintaining the driving force of the entire vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The control device described in Patent Document 1 suppresses the occurrence of partial discharge in the insulating portion of the motor coil while suppressing a decrease in the output of the entire vehicle by suppressing the driving of the motor at an operating point where partial discharge occurs. However, even in a vehicle equipped with only one motor or a vehicle equipped with two or more motors, due to various requirements such as maintaining the running stability of the vehicle, there are cases where the operating point of the motor cannot be changed to an operating point where partial discharge does not occur, and there are cases where the occurrence of partial discharge cannot be avoided.

[0005] The present invention is made by paying attention to the above technical problems, and an object thereof is to provide an insulation deterioration determination device capable of determining deterioration of an insulation part of an electric motor due to occurrence of partial discharge.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention is an insulation deterioration determination device including a power control unit having a plurality of switch elements, and an electric motor that is driven by applying a voltage to a plurality of coils by controlling the power control unit and has an insulation part including between the plurality of coils, wherein an operating point of the electric motor based on the torque and rotational speed of the electric motor is determined every predetermined period, it is determined whether the operating point of the electric motor is a predetermined partial discharge occurrence operating point at which partial discharge occurs due to a surge voltage associated with switch control of the switch element, the number of times the operating point of the electric motor is the partial discharge occurrence operating point is accumulated, and when the accumulated number of times the operating point of the electric motor is the partial discharge occurrence operating point is equal to or more than a predetermined number of times, it is determined that the insulation part is insulation deteriorated.

Effects of the Invention

[0007] According to the present invention, the operating point of the electric motor is determined every predetermined period, and when the accumulated number of times the operating point of the electric motor is the partial discharge occurrence operating point is equal to or more than a predetermined number of times, it is determined that the insulation part constituting the electric motor is insulation deteriorated. Therefore, even when partial discharge unavoidably occurs according to the torque and rotational speed required for the electric motor, deterioration of the insulation part can be appropriately determined. Therefore, it is possible to appropriately take measures corresponding to deterioration of the insulation part, such as notifying the user of deterioration of the insulation part or switching to appropriate control for suppressing further deterioration of the insulation part.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiment for Carrying Out the Invention

[0009] The present invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples when the present invention is embodied, and do not limit the present invention.

[0010] The electric motor in the embodiment of the present invention can be configured in the same manner as a motor or a generator provided as a driving power source of a conventional electric vehicle or a hybrid vehicle. Specifically, it can be configured by a permanent magnet type synchronous motor composed of a rotor provided with a plurality of permanent magnets arranged in the circumferential direction and a stator provided so as to surround the rotor and having a plurality of coils wound around it at predetermined intervals in the circumferential direction. These coils are applied with different voltages from adjacent coils and are insulated and coated with varnish or the like. That is, the insulation coating insulates between adjacent coils and corresponds to the "insulating portion" in the embodiment of the present invention.

[0011] A power storage device, which is a DC power source composed of a lithium-ion battery, a nickel-metal hydride battery, or an all-solid-state battery, etc., is electrically connected to those coils. Since this power storage device outputs a DC voltage and is charged when a DC voltage is applied, a power control unit including a converter and an inverter is provided between the power storage device and each coil. These converters and inverters include a plurality of switching elements such as transistors, and are configured to step up or step down, or switch between a DC voltage and an AC voltage by switch-controlling the switching elements. That is, the converters and inverters are switch-controlled according to the torque and speed required by the motor.

[0012] In the insulation degradation determination device according to an embodiment of the present invention, a converter or an inverter is switch-controlled to control a motor, and partial discharge occurs due to the surge voltage generated at that time, and the degradation of an insulating portion such as an insulating film due to the partial discharge is determined. Specifically, the insulation degradation determination device is configured by a controller mainly including a microcomputer, similar to the controller provided in a conventional vehicle, and signals are input from various sensors provided in the vehicle, and based on the input signals, arithmetic expressions, maps, etc. stored in advance, it is configured to determine the degradation of the insulating portion.

[0013] FIG. 1 shows an example of a partial discharge map stored in the insulation degradation determination device. The partial discharge map shown in FIG. 1 is a map that defines the motor operating points where partial discharge occurs. The rotational speed of the motor is taken on the horizontal axis, and the torque of the motor is taken on the vertical axis, and the operating region where partial discharge occurs is hatched. Note that the motor operating points where partial discharge occurs are determined in advance by experiments or simulations. This motor operating point corresponds to the "motor operating point" in the embodiment of the present invention.

[0014] As shown in FIG. 1, when the motor operating point determined by the torque and rotational speed of the motor is within the hatched region (partial discharge occurrence operating point), partial discharge occurs. Such partial discharge varies according to the temperature of the motor and the atmospheric pressure at the position where the coil is provided. Therefore, the insulation degradation determination device stores a plurality of partial discharge maps that define the regions where partial discharge occurs according to the motor temperature and the atmospheric pressure.

[0015] FIG. 2 shows a flowchart for explaining an example of control executed by the insulation deterioration determination device, and this control example is repeatedly executed at predetermined predetermined cycles. In the control example shown in FIG. 2, first, the detection value of the temperature sensor provided in the motor and the detection value of the pressure sensor that detects the atmospheric pressure in the motor housing are acquired (step S1). Subsequently, among the plurality of partial discharge maps stored in the insulation deterioration determination device, the partial discharge map corresponding to the motor temperature and the atmospheric pressure read in step S1 is read (step S2).

[0016] Therefore, when the motor temperature and the atmospheric pressure change as shown in FIG. 3, when this routine is being executed at time t1, in step S1, the motor temperature Te1 and the atmospheric pressure P1 are acquired, and in step S2, the partial discharge map corresponding to those motor temperature Te1 and atmospheric pressure P1 is read.

[0017] Next, the motor operating point is read (step S3). That is, the torque and the rotational speed of the motor are read. The torque of the motor in this step S3 may be the torque actually output from the motor or may be a torque command signal. That is, the torque of the motor may be read based on the detection signal of a torque sensor that detects the output torque of the motor, or the torque of the motor may be read based on a command signal to a power control unit for controlling the motor. Similarly, the rotational speed of the motor may be the actual rotational speed of the motor or may be a rotational speed command signal of the motor. That is, the rotational speed of the motor may be read based on the detection signal of a rotational speed sensor such as a resolver that detects the rotational speed of the motor, or the rotational speed of the motor may be read based on a command signal to a power control unit for controlling the motor.

[0018] Therefore, when the motor torque and the motor rotational speed change as shown in FIG. 3, when this routine is being executed at time t1, in step S3, the motor torque To1 and the motor rotational speed N1 are acquired.

[0019] Subsequently, it is determined whether the motor operating point read in step S3 is a partial discharge generation operating point in the partial discharge map read in step S2 (step S4). If it is affirmatively determined in step S4 that the motor operating point is a partial discharge generation operating point, the number of occurrences of partial discharge is accumulated (step S5). If it is negatively determined in step S4 because the motor operating point is not a partial discharge generation operating point, this routine is terminated once as it is.

[0020] Subsequent to step S5, it is determined whether the cumulative value of the number of occurrences of partial discharge (cumulative number of partial discharges) is equal to or greater than a predetermined number of times (step S6). This step S6 is a step for determining whether the degree of insulation deterioration of the insulating portion has reached a predetermined degree. The relationship between the cumulative number of partial discharges and the degree of insulation deterioration of the insulating portion can be obtained in advance through experiments, simulations, etc., and the cumulative number of partial discharges corresponding to the predetermined degree can be set as the predetermined number of times in step S6.

[0021] If it is affirmatively determined in step S6 that the cumulative number of partial discharges is equal to or greater than the predetermined number of times, it is determined that there is insulation deterioration (step S7), and this routine is terminated once. On the contrary, if it is negatively determined in step S6 because the cumulative number of partial discharges is less than the predetermined number of times, this routine is terminated once as it is. If it is determined that there is insulation deterioration, for example, a warning lamp may be lit or a warning sound may be generated to notify the driver in order to prompt inspection, the output voltage from the power storage device may be decreased, or the temperature limit of the motor may be switched to a temperature below which partial discharge does not occur. Alternatively, by restricting the remaining charge amount of the power storage device, an increase in the output voltage of the power storage device may be suppressed, or the output voltage of the boost or buck converter may be suppressed.

[0022] As described above, the motor operating point is determined at each predetermined period, and when the cumulative number of times that the motor operating point is the partial discharge generation operating point is equal to or more than a predetermined number of times, it is determined that the insulating portion constituting the motor is insulatingly deteriorated. Therefore, even when partial discharge inevitably occurs according to the torque and rotational speed required for the motor, the deterioration of the insulating portion can be appropriately determined. Therefore, appropriate measures corresponding to the deterioration of the insulating portion can be appropriately taken, such as notifying the user of the deterioration of the insulating portion or switching to appropriate control for suppressing further deterioration of the insulating portion.

Claims

【Claim 1】 An insulation degradation determination device comprising: a power control unit having a plurality of switch elements; and an electric motor that drives by applying a voltage to a plurality of coils by controlling the power control unit and has an insulating portion including between the plurality of coils, determines an operating point of the electric motor based on the torque and rotational speed of the electric motor at predetermined intervals, determines whether or not the operating point of the electric motor is a predetermined partial discharge generation operating point at which partial discharge occurs due to a surge voltage associated with switch control of the switch element, accumulates the number of times the operating point of the electric motor is the partial discharge generation operating point, and determines that the insulating portion has deteriorated in insulation when the accumulated number of times the operating point of the electric motor is the partial discharge generation operating point is equal to or greater than a predetermined number of times. An insulation degradation determination device characterized by the above.

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