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JP-2026074773-A - Life diagnostic device for passive components

JP2026074773AJP 2026074773 AJP2026074773 AJP 2026074773AJP-2026074773-A

Abstract

[Problem] To provide a passive component life diagnostic device that can estimate the lifespan of passive components in a circuit to be diagnosed, while suppressing increased complexity of configuration and rising costs. [Solution] The life diagnostic device 70 includes power supplies 72 and 73 and is connected to a circuit to be diagnosed, which includes passive components, so that an energizing circuit is formed from the power supplies through the passive components. The circuit impedance is measured when the energizing circuit is energized, and the characteristic value of the passive component is calculated based on the measured circuit impedance. The life of the passive component is estimated based on the initial value of the characteristic value of the passive component and the calculated characteristic value. [Selection Diagram] Figure 2

Inventors

  • 西町 誠一郎
  • 岩田 由美

Assignees

  • 株式会社SOKEN
  • 株式会社デンソー

Dates

Publication Date
20260507
Application Date
20241021

Claims (11)

  1. A life diagnostic device for passive components, comprising at least one of a capacitor, a reactor, and a resistor, The life diagnostic device includes a power supply (72, 73) and is connected to a circuit to be diagnosed, which includes the passive component, such that a power supply circuit is formed from the power supply through the passive component. The lifespan diagnostic device is, A measuring unit (75) that measures the circuit impedance when the current is applied to the current-carrying circuit, and a calculation unit (76) that calculates the characteristic value of the passive component based on the circuit impedance measured by the measuring unit, A life diagnostic device comprising: an estimation unit (77) that estimates the lifespan of the passive component based on the initial value of the characteristic value of the passive component and the characteristic value calculated by the calculation unit.
  2. The power supply of the life diagnostic device energizes the current supply circuit by applying an AC voltage with a swept frequency. The passive component includes at least one of a capacitor and a reactor, The measurement unit measures the impedance frequency characteristics, which are the circuit impedance of the current-carrying circuit, when an AC voltage with a swept frequency is applied. The life diagnostic device according to claim 1, wherein the calculation unit calculates the characteristic value of the passive component based on the impedance frequency characteristics measured by the measurement unit and the initial impedance frequency characteristics corresponding to the initial characteristic value of the passive component.
  3. The life diagnostic device according to claim 2, wherein the calculation unit calculates the characteristic value of the passive component based on the measured impedance frequency characteristics in a specific frequency range corresponding to the connection position and type of the passive component, and the initial impedance frequency characteristics corresponding to the initial characteristic value of the passive component.
  4. The lifespan diagnostic device is connected to the existing external connection terminals (11, 12, 24) of the circuit to be diagnosed, as described in claim 1.
  5. If the energizing circuit includes a semiconductor switching element (15H), the lifespan diagnostic device commands the control device (40) that controls the circuit to be diagnosed to make the semiconductor switching element conductive, as described in claim 1.
  6. The circuit to be diagnosed is a power conversion circuit that includes a boost circuit and an inverter circuit that converts a DC voltage into an AC voltage for driving an AC motor. The life diagnostic device according to claim 5, wherein the passive component is at least one of a filter capacitor (13) connected to the upstream of the boost circuit, a reactor (14) constituting the boost circuit, a smoothing capacitor (17) that stores the voltage boosted by the boost circuit, and a discharge resistor (16) connected in parallel with the smoothing capacitor.
  7. The life diagnostic device according to claim 6, wherein the power conversion circuit includes two inverter circuits (30, 31) for driving two AC motors.
  8. The semiconductor switching element included in the current supply circuit is provided on the upper arm of the boost circuit, The life diagnostic device according to claim 6, wherein the life diagnostic device commands the control device to make the semiconductor switching element on the upper arm of the boost circuit conductive by giving an instruction signal to the control device so that the control device controls the semiconductor switching element on the upper arm of the boost circuit to be in a conductive state.
  9. The semiconductor switching element included in the current supply circuit is provided on the upper arm of the boost circuit, A diode (15DH) is connected in parallel to the semiconductor switching element. The power supply of the life diagnostic device applies a superimposed voltage to the current supply circuit, which is obtained by superimposing a DC voltage with a frequency-swept AC voltage onto the DC voltage. The life diagnostic device according to claim 6, wherein the direction in which the DC current due to the DC voltage is passed is opposite to the forward direction of the diode.
  10. The diagnostic circuit includes a first capacitor (120) whose electrical response to a frequency-swept AC voltage can be observed, and a second capacitor (124) connected downstream of the first capacitor whose electrical response cannot be observed. A storage unit (78) stores the relationship between the operating temperatures of the first capacitor and the second capacitor when the diagnostic target circuit is operating as a temperature stress correlation coefficient, and stores the relationship between the magnitude of the change in the measured capacitance value relative to the initial capacitance value of the first capacitor and the amount of stress as a life curve. A first stress amount calculation unit (S210) calculates the stress amount of the first capacitor based on the capacitance value, which is a specific value of the first capacitor, calculated by the calculation unit, The system includes a second stress amount estimation unit (S220) that estimates the stress amount of the second capacitor by referring to the temperature stress correlation coefficient based on the stress amount of the first capacitor calculated by the first stress amount calculation unit, The life diagnostic device according to claim 1 or 2, wherein the estimation unit estimates the lifespan of the second capacitor based on the amount of stress of the second capacitor calculated by the second stress amount estimation unit.
  11. The life diagnostic device according to claim 10, wherein the second stress amount estimation unit calculates the stress amount of the second capacitor using different temperature stress correlation coefficients depending on the stress amount of the first capacitor calculated by the first stress amount calculation unit.

Description

This disclosure relates to a life diagnostic device for passive components such as capacitors, reactors, and resistors. For example, Patent Document 1 discloses a power conversion system for diagnosing the state of an energy storage device. This power conversion system includes an AC-DC converter that converts AC power supplied from an AC power source into first DC power, and a DC-AC converter that converts the first DC power into AC power and outputs it to an AC motor. Furthermore, the power conversion system includes a DC-DC converter that converts the first DC power into second DC power and outputs it to the energy storage device, and also converts the second DC power supplied from the energy storage device into first DC power and outputs it to the DC-AC converter. The DC-DC converter has a function for diagnosing the state of the energy storage device. Specifically, the DC-DC converter performs at least one of the following: superimposing an AC voltage onto the DC voltage in the second DC power source, and superimposing an AC current onto the DC current in the second DC power source. The DC-DC converter then detects at least one of the DC voltage detection value with the AC voltage superimposed, and the DC current detection value with the AC current superimposed, and diagnoses the state of the energy storage device based on the detection results. International Publication No. 2015/125279 This is a configuration diagram showing an example of the configuration of a power conversion circuit to which the life diagnostic device according to the first embodiment is applied.This is a diagram showing an example of the configuration of the lifespan diagnostic device according to this embodiment.This flowchart shows the processes performed by the measurement unit, calculation unit, and estimation unit in the control device of a life diagnostic device.This graph shows an example of measured and selected values for the frequency characteristics of circuit impedance.This diagram shows the equivalent circuit of the circuit targeted for diagnosis by the lifespan diagnostic device.This figure shows the target parameter, target frequency band, and example formulas for calculating the characteristic values of each passive component.This figure shows a modified example of the lifespan diagnostic device of the first embodiment.This figure shows another modified example of the lifespan diagnostic device of the first embodiment.This figure shows yet another modified example of the lifespan diagnostic device of the first embodiment.This is a configuration diagram showing an example of the configuration of a voltage generation circuit to which the life diagnostic device according to the second embodiment is applied.This flowchart shows an example of a process performed in the lifespan diagnostic device according to the second embodiment.This graph shows an example of the life curves for the first and second capacitors.This graph shows an example of the temperature stress correlation coefficient between the first and second capacitors. The following describes preferred embodiments of this disclosure with reference to the drawings. Note that identical or similar configurations may be omitted from the description by assigning the same reference numeral across multiple drawings. If only a portion of a configuration is described in each embodiment, the configuration of other embodiments described earlier may be applied to the remaining parts of that configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations from multiple embodiments may be partially combined, even if not explicitly stated, as long as there are no particular problems with the combination. (First Embodiment) The life diagnostic device according to this embodiment can be used, for example, to diagnose the life of passive components (e.g., resistors, reactors, and/or capacitors) of a power converter for driving an electric motor. The electric motor can be used, for example, as a power source for a mobile body. Examples of mobile bodies include electric vehicles such as electric electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), electric aircraft such as drones and electric vertical take-off and landing aircraft (eVTOLs), ships, construction machinery, and agricultural machinery. However, the electric motor is not limited to being used as a power source for a mobile body; for example, it may be used to drive a compressor in an air conditioning system. In Figure 1, the first and second motor generators (hereinafter referred to as MGs) 50 and 60, acting as electric motors, are, for example, three-phase AC rotating electric machines. Figure 1 shows an example where the U-phase coils, V-phase coils, and W-phase coils of the first and second MGs 50 and 60 are connected in a Y configuration. The U-phase coils, V-phase coils, and W-ph