JP7726232B2 - Partial discharge detector - Google Patents

Description

The present invention relates to a partial discharge detection device for coils.

Motor systems, which serve as the power source for EVs and HEVs, consist of a battery, inverter, motor controller, and motor, and the motor is driven by the inverter. The inverter generates the sinusoidal current required to drive the motor by repeatedly switching between the inverter's inputs at high speeds. During this process, a surge voltage exceeding the battery voltage is generated at the inverter's output terminals with each switching operation. This surge voltage propagates through the cable between the inverter and motor and into the motor, momentarily applying a voltage greater than the battery voltage across the motor's coils. This surge voltage varies depending on the motor cable routing, cable length, and operating conditions, and can reach 1.3 times the operating voltage or more. When this surge voltage is applied across the motor's coils, it is known to generate minute electrical discharges known as partial discharges through the coil coating. If this partial discharge continues, the erosion of the coil coating spreads, eventually leading to insulation breakdown. Monitoring partial discharges is important for determining whether the coil windings are deteriorating and whether there is a high risk of damage to the windings.

Given this background, there is a growing need to monitor motor insulation performance online. Patent Document 1 describes a partial discharge detection device that uses an antenna-type sensor to detect the current flowing in the ground wire of equipment to which an AC power supply voltage is applied, removes low-frequency components from the detected current, converts it into an envelope signal, and uses this signal, along with the power supply current detected by a current sensor, as inputs to determine whether or not a partial discharge has occurred. Patent Document 2 describes a partial discharge detection device that uses a narrow-band filter to filter the detection signal from a partial discharge sensor installed within the frame of a rotating electric machine, and measures and displays the intensity of the maximum partial discharge level that stably occurs in each cycle of the voltage frequency applied to the stator winding of the peak-detecting rotating electric machine.

JP 2019-90693 A Japanese Patent Application Laid-Open No. 2002-71742

The partial discharge detection devices described in Patent Documents 1 and 2 require the use of high-frequency current sensors or RF antennas to detect partial discharges that occur between the coils of a rotating electrical machine. Both methods require the sensor to be installed separately inside or near the rotating electrical machine, which increases costs. Furthermore, in order to achieve stable sensitivity, installation locations are limited, and additional work on the rotating electrical machine housing is required for installation.

The object of the present invention is to provide a partial discharge detection device that can detect partial discharge in a coil without adding a sensor to detect partial discharge.

One aspect of the present invention is a partial discharge detection device for a coil, wherein the coil is equipped with a thermistor for temperature detection, and the device extracts a first frequency band component from the signal output by the thermistor, extracts a second frequency band component corresponding to partial discharge, which is a high frequency band, from the signal output by the thermistor, and detects partial discharge occurring in the coil based on both the first frequency band component and the second frequency band component.

Here, it is preferable to provide a high-pass filter that extracts the second frequency band component corresponding to partial discharge from the voltage output by the thermistor, and a pulse converter that outputs a pulse signal when the output voltage of the high-pass filter is equal to or greater than a predetermined reference value, and to detect partial discharge occurring in the coil based on the pulse signal.

It is also preferable to include a temperature detection circuit that extracts the first frequency band component from the signal output by the thermistor and generates a temperature signal indicating the temperature of the coil, a signal strength threshold setter that corrects the second frequency band component in accordance with the temperature signal, and detect partial discharges occurring in the coil based on the corrected second frequency band component.

Furthermore, it is preferable that the coil is provided in a rotating electric machine, the rotation of which is controlled by an inverter, and that the rotating electric machine is provided with a partial discharge discriminator that discriminates the occurrence of partial discharge in the coil based on both the components of the first frequency band and the components of the second frequency band in accordance with the timing of the rise or fall of an inverter control signal of the inverter.

It is also preferable to provide an insulation degradation level determiner that, when a partial discharge is detected in the coil, determines the degree of insulation degradation of the coil based on the frequency of partial discharge occurrences.

It is also preferable to provide an insulation degradation level determiner that determines the degree of insulation degradation of the coil based on the motor current flowing through the coil when partial discharge occurring in the coil is detected.

It is also preferable to limit the drive voltage of the coil when partial discharge occurring in the coil is detected.

The partial discharge detection device of the present invention uses a thermistor for measuring temperature that is installed in the coil, making it possible to detect partial discharge in the coil without adding a separate sensor.

1 is a diagram illustrating a configuration of a partial discharge detection device according to a first embodiment. FIG. 2 is a schematic diagram showing the frequency dependence of the dielectric constant and dielectric loss factor of an insulating material. 2 is a schematic diagram showing the temperature dependence of the dielectric constant and dielectric loss factor of an insulating material. FIG. FIG. 10 is a diagram showing an example of the temperature dependence of a partial discharge inception voltage. FIG. 3 is a diagram showing the relationship between the output voltage of the inverter and the current flowing through the rotating electric machine. FIG. 10 is a diagram showing an example of a waveform of a pulse voltage on which a surge is superimposed. FIG. 10 is a diagram showing an example of an observed waveform of partial discharge detected by a thermistor. FIG. 10 is a diagram illustrating a configuration of a partial discharge detection device according to a second embodiment. FIG. 10 is a diagram illustrating a configuration of a partial discharge detection device according to a third embodiment. FIG. 10 is a diagram illustrating a configuration of a partial discharge detection device according to a fourth embodiment.

First Embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating understanding of the present invention, and can be appropriately changed according to the application, purpose, specifications, etc. Furthermore, it is originally anticipated that the components of the embodiments and modified examples described below can be selectively combined.

As shown in FIG. 1, the partial discharge detection device 100 in the first embodiment is connected to a rotating electric machine 110, an inverter 112, and a motor controller 114. The partial discharge detection device 100 detects partial discharges that may occur in the coil 110a provided in the rotating electric machine 110.

The rotating electric machine 110 has multiple coils 110a. The rotating electric machine 110 is driven by the output voltage of the inverter 112. The rotating electric machine 110 is installed in, for example, an electric vehicle or a hybrid electric vehicle.

The rotating electric machine 110 is equipped with a thermistor 110b inside the housing. The thermistor 110b is used to detect the temperature inside the housing. Thermistor 110b outputs a voltage signal proportional to the internal temperature of the rotating electric machine 110. In other words, the thermistor 110b outputs a temperature corresponding to the temperature of the coil 110a as a voltage signal.

The output voltage of the inverter 112 is controlled by, but not limited to, PWM control or single-pulse control. The inverter 112 is configured, for example, as a three-phase inverter circuit in which three arms, each with a series-connected power switching element, are connected in parallel. The inverter 112 is controlled to turn on/off by an inverter control signal output from the motor controller 114. By turning on/off the switching elements that make up the inverter 112, a voltage is applied to the coil 110a of the rotating electric machine 110, causing a sinusoidal current to flow through the coil 110a.

The motor controller 114 outputs an inverter control signal to the inverter 112. The inverter control signal is, for example, a PWM control signal. As described below, the motor controller 114 receives the output of the temperature detection circuit 10 and the output of the partial discharge determiner 16, and controls the output of the rotating electric machine 110.

In this embodiment, the rotating electric machine 110 is a motor, and a motor controller 114 is provided as an example configuration, but if the rotating electric machine 110 is a generator, it may also be a generator controller.

In rotating electric machines 110 used as power sources for electric vehicles and hybrid electric vehicles, the sinusoidal current required to drive the rotating electric machine 110 is generated by rapidly and repeatedly switching the inverter 112's switching elements on and off. In this case, a surge voltage that exceeds the battery voltage is superimposed on the output terminal of the inverter 112 with each switching operation. This surge voltage propagates through the cable between the inverter 112 and the rotating electric machine 110 to the inside of the motor, and a high voltage exceeding the battery voltage is momentarily applied across the coil 110a.

Figures 2 and 3 are schematic diagrams showing the frequency and temperature characteristics of the dielectric constant ε' and dielectric loss factor ε" of the dielectric used in the insulating coating material of coil 110a. In Figures 2 and 3, the dielectric constant ε' of the dielectric is shown by a solid line, and the dielectric loss factor ε" of the dielectric is shown by a dashed line.

The dielectric constant ε' is a value that represents the magnitude of the charge generated by polarization per unit electric field when an electric field is applied to a dielectric; the higher the dielectric constant, the greater the charge generated per unit electric field. Therefore, when an AC electric field is applied to a dielectric, the higher the dielectric constant ε', the greater the power consumption, and this power consumption is expressed as the dielectric loss factor ε". In both the frequency and temperature characteristics, the dielectric loss factor ε" reaches a maximum at a specific frequency fm or a specific temperature Tm. Furthermore, the dielectric constant ε' exhibits characteristics that increase or decrease around this maximum point.

For materials that require dielectric strength, a small dielectric constant ε' is desirable. However, as shown in Figure 3, the dielectric constant ε' tends to increase as the environmental temperature rises. In other words, the dielectric strength of an insulating material decreases as the temperature rises. In this way, the temperature characteristics and dielectric strength of a dielectric are closely related, and the voltage at which partial discharges begin is affected by temperature. In other words, partial discharge characteristics differ when the temperature differs from room temperature. Specifically, the partial discharge inception voltage exhibits a tendency to decrease as the environmental temperature increases, as shown in Figure 4.

Figure 5 shows the relationship between the output voltage (pulse width) of the inverter 112 and the current flowing through the coil 110a of the rotating electric machine 110. The output current of the rotating electric machine 110 is controlled by modulating the output voltage width of the inverter 112.

The partial discharge detection device 100 comprises a temperature detection circuit 10, a signal intensity threshold setter 11, a high-pass filter 12, a pulse converter 14, a partial discharge discriminator 16, and a PWM edge detector 18. The partial discharge detection device 100 extracts high-frequency components in a high-frequency band corresponding to partial discharge from the signal output by the thermistor 110b, extracts low-frequency components in a band lower than the high-frequency components from the signal output by the thermistor 110b, and detects partial discharge occurring in the coil 110a based on both the low-frequency components and the high-frequency components.

The temperature detection circuit 10 is connected to thermistor 110b. The temperature detection circuit 10 removes high-frequency components from the voltage signal output from thermistor 110b and outputs a temperature signal indicating the temperature inside the housing of the rotating electric machine 110. For example, the temperature detection circuit 10 outputs only signals in a frequency band of approximately 10 Hz or less, which is the first frequency band, from the voltage signal output from thermistor 110b as the temperature signal. The temperature signal is input to the motor controller 114 and partial discharge determiner 16.

The motor controller 114 receives a temperature signal from the temperature detection circuit 10 and modulates the control signal for the inverter 112. For example, if the temperature exceeds a predetermined value, it generates a control signal for the inverter 112 to reduce the rotation speed of the rotating electric machine 110. However, the control of the motor controller 114 is not limited to this.

The high-pass filter 12 is connected to thermistor 110b. The high-pass filter 12 passes only the high-frequency components of the voltage signal output from thermistor 110b and outputs a signal containing information about the dielectric constant of the dielectric of coil 110a. The high-pass filter 12 outputs, for example, a signal in the second frequency band of approximately 10 MHz or more and several hundred MHz or less from the voltage signal output from thermistor 110b as a detection signal. In other words, the high-pass filter 12 extracts the high-frequency components of the electromagnetic waves caused by partial discharge from the voltage signal of thermistor 110b.

The signal strength threshold setter 11 is connected to the temperature detection circuit 10. Based on the temperature signal output from the temperature detection circuit, the signal strength threshold setter 11 sets a signal strength threshold determined from the temperature characteristics of the partial discharge inception voltage as shown in Figure 4.

When a partial discharge occurs, electromagnetic waves generated in coil 110a propagate to thermistor 110b. Thermistor 110b generates a high-frequency voltage change due to a resistance change caused by heat generated when absorbing the electromagnetic waves. High-pass filter 12 passes the high-frequency components specific to partial discharge contained in the output voltage of thermistor 110b and outputs the signal to pulse converter 14.

The pulse converter 14 extracts the output voltage of the high-pass filter 12 that is greater than the signal strength threshold output by the signal strength threshold setter 11 and outputs it as a pulse signal. The pulse converter 14 obtains a peak value from the detection signal output from the high-pass filter 12. The pulse converter 14 may include a comparator 14a and a pulse detector 14b. The comparator 14a detects when the detection signal output from the high-pass filter 12 is greater than the signal strength threshold output by the signal strength threshold setter 11. That is, the comparator 14a outputs the detection signal as is when the detection signal output from the high-pass filter 12 is greater than the signal strength threshold output by the signal strength threshold setter 11, and does not output a signal when the detection signal is less than the signal strength threshold. The pulse detector 14b detects and outputs the peak value of the signal output from the comparator 14a. The detected peak value is input to the partial discharge discriminator 16.

The partial discharge determiner 16 receives a signal indicating the peak value output from the pulse converter 14 and determines whether a partial discharge has occurred in the rotating electric machine 110. The partial discharge determiner 16 receives the temperature signal detected by the temperature detection circuit 10 and the peak value input from the pulse converter 14 to determine whether a partial discharge has occurred. In other words, since the partial discharge inception voltage changes depending on the temperature of the rotating electric machine 110, the peak value output from the pulse converter 14 is corrected in accordance with the temperature signal detected by the temperature detection circuit 10 so that the partial discharge determiner 16 can correctly determine the partial discharge inception voltage. As shown in Figure 4, generally, the partial discharge inception voltage of an insulating material decreases as the ambient temperature increases, so it is preferable to perform a correction so that the signal strength threshold is increased as the temperature detected by the temperature detection circuit 10 increases. Note that the specific means of correction is not particularly limited.

The partial discharge determiner 16 also receives a signal indicating the on/off timing of the inverter 112's switching elements from a PWM edge detector 18, which detects the on/off timing of the inverter 112's switching elements. The PWM edge detector 18 can detect the on/off timing of the inverter 112's switching elements based on the phase inversion (voltage inversion) of the inverter 112's control signal. The greater the absolute value of the surge voltage and the voltage change rate, the more likely partial discharges are to occur. That is, partial discharges are more likely to occur with each rising or falling edge of a pulse in the inverter 112's output voltage waveform, in other words, at the on/off timing of the inverter 112's switching. Therefore, the partial discharge determiner 16 determines that partial discharge has occurred in the rotating electric machine 110 when the peak value input from the pulse converter 14 is equal to or greater than a predetermined reference value within a predetermined period from the on/off timing of the inverter 112's switching elements.

A signal indicating the partial discharge determination result from the partial discharge determiner 16 is output to the motor controller 114. The motor controller 114 may receive the partial discharge determination result from the partial discharge determiner 16 and, if it determines that a partial discharge has occurred, control the inverter 112 so that the current flowing through the coil 110a of the rotating electric machine 110 is smaller than normal.

Figure 6 shows an example of a pulse voltage waveform when a surge is superimposed on the pulse voltage output by inverter 112. The surge voltage is superimposed at the rising and falling edges of the output voltage of inverter 112.

Figure 7 shows the output voltage waveform after high-pass filtering of the RF antenna and thermistor 110b at the falling edge of the voltage when the voltage waveform shown in Figure 6 is applied to a rectangular wire. The voltage waveform from the RF antenna is shown for comparison as a conventional method.

As shown in Figure 7, the RF antenna output voltage waveform shows a large amplitude voltage near the peak of the surge voltage. In other words, with conventional methods, partial discharges can be detected because a large output voltage is observed at the RF antenna.

In the output voltage waveform of thermistor 110b, a voltage with a superimposed high frequency is generated in synchronization with the ringing of the surge voltage. Similar to the output voltage of an RF antenna, this high-frequency voltage has the largest amplitude near the peak value of the surge voltage. Therefore, partial discharge can be detected by extracting high-frequency components higher than the ringing frequency from the output voltage of thermistor 110b.

In the partial discharge detection device 100, the high-frequency voltage, current, light, sound waves, and electromagnetic waves generated by the occurrence of partial discharge in the coil 110a of the rotating electric machine 110 are detected as a change in resistance in the thermistor 110b. The high-pass filter 12 extracts high-frequency components corresponding to the electromagnetic waves during partial discharge from a frequency range higher than the frequency range corresponding to the temperature signal of the rotating electric machine 110. The pulse converter 14 then extracts the peak value of the signal output from the high-pass filter 12, and the partial discharge discriminator 16 determines whether or not a partial discharge has occurred based on this peak value.

As a result, the partial discharge detection device 100 can detect partial discharges using the thermistor 110b that has traditionally been provided in the rotating electric machine 110, without the need to provide a separate RF antenna, high-frequency current sensor, etc.

Furthermore, in the partial discharge detection device 100, the partial discharge discriminator 16 corrects the signal strength threshold of the signal strength threshold setter 11 in accordance with the temperature detected in the temperature detection circuit 10, thereby reducing the influence of temperature on the partial discharge inception voltage. This makes it possible to more accurately detect partial discharges that change according to the ambient temperature while reducing the influence of the temperature of the rotating electric machine 110.

Second Embodiment
8 shows the configuration of a partial discharge detection device 120 according to the second embodiment. Similar to the partial discharge detection device 100 according to the first embodiment, the partial discharge detection device 120 is connected to a rotating electric machine 110, an inverter 112, and a motor controller 114. The partial discharge detection device 120 detects partial discharge that may occur in a coil 110a provided in the rotating electric machine 110.

In addition to the components of the partial discharge detection device 100, the partial discharge detection device 120 is equipped with a partial discharge current detector 20, a memory 22, and an insulation deterioration level determiner 24. Descriptions of the temperature detection circuit 10, signal strength threshold setter 11, high-pass filter 12, pulse converter 14, partial discharge discriminator 16, and PWM edge detector 18 included in the partial discharge detection device 100 will be omitted except for parts with different functions.

When partial discharge is detected, the partial discharge detector 16 outputs a signal indicating that a partial discharge has occurred. The signal indicating that a partial discharge has occurred output from the partial discharge detector 16 is stored in memory 22.

The partial discharge current detector 20 receives the signal output from the partial discharge determiner 16 and the motor current value obtained from the inverter 112. The partial discharge current detector 20 stores the motor current value when the signal is input from the partial discharge determiner 16 in the memory 22. That is, the partial discharge current detector 20 stores the current value flowing through the rotating electric machine 110 when a partial discharge is occurring in the memory 22. Furthermore, when a signal is input from the partial discharge determiner 16, the partial discharge current detector 20 outputs the signal and a signal indicating the motor current value flowing through the rotating electric machine 110 at that timing to the insulation degradation level determiner 24.

The insulation degradation level determiner 24 determines the insulation degradation level of the rotating electric machine 110 based on the motor current value data stored in the memory 22 when a signal is input from the partial discharge current detector 20 or at predetermined intervals. The insulation degradation level of the rotating electric machine 110 can be determined, for example, based on the frequency of partial discharges or the rate of change of the motor current when a partial discharge occurs. Specifically, the higher the frequency of partial discharges, the more advanced the insulation degradation of the rotating electric machine 110 can be determined. Furthermore, the smaller the motor current value when a partial discharge occurs, the more advanced the insulation degradation of the rotating electric machine 110 can be determined. The partial discharge frequency and the rate of change of the motor current when a partial discharge occurs may be calculated each time a signal is input from the partial discharge current detector 20, or the calculated values may be stored in the memory 22 and updated each time a partial discharge is detected. The insulation degradation level may be determined as a result of whether a predetermined degradation threshold is exceeded, or may be a result indicating the degree of insulation degradation at multiple levels.

The partial discharge detection device 120 of the second embodiment can determine the degree of insulation deterioration based on the frequency of partial discharge occurrence and the rate of change of the motor current value when partial discharge occurs. This makes it possible to determine whether the degree of insulation deterioration is within an acceptable level.

Furthermore, if it is determined that the tolerance level has been exceeded, a configuration may be adopted in which a warning signal is output to notify that the insulation degradation has exceeded the tolerance level, or the motor output is restricted. For example, a configuration may be adopted in which an alarm is issued to notify that the insulation performance of the coil 110a in the rotating electric machine 110 has deteriorated. As an example of the notification, in the case of an electric vehicle or hybrid electric vehicle, an alarm indicating insulation deterioration of the coil 110a may be displayed on the front panel, or information may be sent from the electric vehicle or hybrid electric vehicle to the dealer via a wireless network. The user or dealer who receives the notification can take the necessary measures. However, examples of notifications are not limited to these.

Third Embodiment
9 shows the configuration of a partial discharge detection device 122 according to the third embodiment. The partial discharge detection device 122 further includes a motor drive upper limit voltage setter 26 in addition to the components of the partial discharge detection device 100 according to the second embodiment.

The motor drive upper limit voltage setter 26 receives the insulation degradation level output from the insulation degradation level determiner 24 and sets the motor drive upper limit voltage for the motor controller 114. For example, if the insulation degradation level determiner 24 determines that insulation degradation has progressed, it outputs a degradation level determination signal to the motor drive upper limit voltage setter 26. Upon receiving the degradation level determination signal, the motor drive upper limit voltage setter 26 outputs a voltage limit signal to the motor controller 114. Upon receiving the voltage limit signal from the motor drive upper limit voltage setter 26, the motor controller 114 controls the inverter 112 to limit the upper limit of the motor drive voltage to the motor drive upper limit voltage indicated by the voltage limit signal. This makes it possible to suppress the occurrence of partial discharge in the rotating electric machine 110.

Furthermore, if the insulation degradation level determiner 24 determines the degree of insulation degradation at multiple levels, the motor drive upper limit voltage setter 26 may output a voltage limit signal so that the motor drive upper limit voltage corresponds to the level of the insulation degradation level. Note that the operation of the insulation degradation level determiner 24 is an example and does not limit the method of setting the motor drive upper limit voltage according to the degree of insulation degradation.

<Fourth embodiment>
10 shows the configuration of a partial discharge detection device 124 according to the fourth embodiment. The partial discharge detection device 124 is configured such that the input to the PWM edge detector 18 in the partial discharge detection device 100 of the first embodiment is changed and a delay circuit 28 is further provided.

In this embodiment, the PWM edge detector 18 detects the on/off timing of the inverter 112's switching elements based on the inverter 112 switching control signal from the motor controller 114, and outputs the detected timing to the partial discharge determiner 16. Here, the delay circuit 28 receives the switching control signal output from the motor controller 114, delays the switching control signal, and outputs it to the PWM edge detector 18. The delay circuit 28 delays the time from when the motor controller 114's switching control signal is input to the inverter 112 until the switching elements in the inverter 112 are actually turned on/off.

The line voltage of the inverter 112 is high, and if a DC/DC converter is provided upstream of the inverter 112, the configuration of the PWM edge detector 18 in the partial discharge detection device 100 of the first embodiment becomes complex. In the partial discharge detection device 124 of this embodiment, the configuration of the PWM edge detector 18 can be simplified by using the switching control signal of the motor controller 114.

A similar configuration can also be applied to the partial discharge detection device 120 of the second embodiment and the partial discharge detection device 122 of the third embodiment.

[Configuration of the invention]
[Configuration 1]
A coil partial discharge detection device,
The coil includes a thermistor for detecting temperature.
extracting a component of a first frequency band from the signal output by the thermistor;
extracting a component of a second frequency band corresponding to partial discharge, which is a high frequency band, from the signal output by the thermistor;
A partial discharge detection device that detects a partial discharge occurring in the coil based on both the components of the first frequency band and the components of the second frequency band.
[Configuration 2]
The partial discharge detection device according to configuration 1,
a high-pass filter that extracts the second frequency band component corresponding to partial discharge from the voltage output by the thermistor;
a pulse converter that outputs a pulse signal when the output voltage of the high-pass filter is equal to or greater than a predetermined reference value;
A partial discharge detection device that detects partial discharges occurring in the coil based on the pulse signal.
[Configuration 3]
The partial discharge detection device according to configuration 1 or 2,
a temperature detection circuit that extracts the component of the first frequency band from the signal output by the thermistor and generates a temperature signal that indicates the temperature of the coil;
A partial discharge detection device comprising a signal strength threshold setter that corrects the components of the second frequency band in accordance with the temperature signal, and detects partial discharges occurring in the coil based on the corrected components of the second frequency band.
[Configuration 4]
The partial discharge detection device according to any one of configurations 1 to 3,
The coil is provided in a rotating electric machine,
The rotating electric machine is controlled by an inverter,
a partial discharge detector that determines whether a partial discharge has occurred in the coil based on both the components of the first frequency band and the components of the second frequency band in accordance with the timing of a rise or fall of an inverter control signal of the inverter.
[Configuration 5]
The partial discharge detection device according to any one of configurations 1 to 4,
A partial discharge detection device characterized by comprising an insulation degradation level determiner that, when a partial discharge occurring in the coil is detected, determines the degree of insulation degradation of the coil depending on the frequency of partial discharge occurrence.
[Configuration 6]
The partial discharge detection device according to any one of configurations 1 to 4,
A partial discharge detection device characterized by comprising an insulation degradation level determiner that determines the insulation degradation level of the coil depending on the motor current flowing through the coil when a partial discharge generated in the coil is detected.
[Configuration 7]
The partial discharge detection device according to any one of configurations 1 to 6,
A partial discharge detection device characterized in that, when a partial discharge occurring in the coil is detected, the drive voltage of the coil is limited.

10 Temperature detection circuit, 11 Signal strength threshold setter, 12 High-pass filter, 14 Pulse converter, 14a Comparator, 14b Pulse detector, 16 Partial discharge discriminator, 18 PWM edge detector, 20 Partial discharge current detector, 22 Memory, 24 Insulation deterioration degree determiner, 26 Motor drive upper limit voltage setter, 28 Delay circuit, 100, 120, 122, 124 Partial discharge detection device, 110 Rotating electric machine, 110a Coil, 110b Thermistor, 112 Inverter, 114 Motor controller.

Claims (7)

A coil partial discharge detection device,
The coil includes a thermistor for detecting temperature.
extracting a component of a first frequency band from the signal output by the thermistor;
extracting a component of a second frequency band corresponding to partial discharge, which is a frequency band higher than the first frequency band, from the signal output by the thermistor;
A partial discharge detection device that detects a partial discharge occurring in the coil based on both the components of the first frequency band and the components of the second frequency band. The partial discharge detection device according to claim 1,
a high-pass filter that extracts the second frequency band component corresponding to partial discharge from the voltage output by the thermistor;
a pulse converter that outputs a pulse signal when the output voltage of the high-pass filter is equal to or greater than a predetermined reference value;
A partial discharge detection device that detects partial discharges occurring in the coil based on the pulse signal. The partial discharge detection device according to claim 1,
a temperature detection circuit that extracts the component of the first frequency band from the signal output by the thermistor and generates a temperature signal that indicates the temperature of the coil;
A partial discharge detection device comprising a signal strength threshold setter that corrects the components of the second frequency band in accordance with the temperature signal, and detects partial discharges occurring in the coil based on the corrected components of the second frequency band. The partial discharge detection device according to claim 1,
The coil is provided in a rotating electric machine,
The rotating electric machine is controlled by an inverter,
a partial discharge detector that determines whether a partial discharge has occurred in the coil based on both the components of the first frequency band and the components of the second frequency band in accordance with the timing of a rise or fall of an inverter control signal of the inverter. The partial discharge detection device according to claim 1,
A partial discharge detection device characterized by comprising an insulation degradation level determiner that, when a partial discharge occurring in the coil is detected, determines the degree of insulation degradation of the coil depending on the frequency of partial discharge occurrence. The partial discharge detection device according to claim 1,
A partial discharge detection device characterized by comprising an insulation degradation level determiner that determines the insulation degradation level of the coil depending on the motor current flowing through the coil when a partial discharge generated in the coil is detected. The partial discharge detection device according to claim 1,
A partial discharge detection device characterized in that, when a partial discharge occurring in the coil is detected, the drive voltage of the coil is limited.