Abstract: A power conversion device including a switching element includes: a temperature change estimation unit estimating temperature change in a semiconductor chip containing the switching element; a number calculator calculating the number of power cycles to fracture of the semiconductor chip due to power cycles; and a degradation degree calculator computing a degree of degradation of the semiconductor chip caused by the power cycles. The temperature change estimation unit calculates a maximum value and a minimum value of temperature of the semiconductor chip in one power cycle based on a first threshold of temperature fall allowed when it is determined that the temperature of the semiconductor chip is rising, and a second threshold of temperature rise allowed when it is determined that the temperature of the semiconductor chip is falling. The number calculator calculates the number of power cycles to fracture based on the maximum value and the minimum value.

Abstract: A power conversion device includes a cooling fan, a cooling fan control unit that controls the drive amount of the cooling fan, and an electrolytic capacitor whose life varies according to the drive amount of the cooling fan. The cooling fan control unit controls the drive amount based on the relationship between the drive amount, the life of the cooling fan, and the life of the electrolytic capacitor.

Abstract: A power conversion device includes a cooling fan, a cooling fan control unit that controls the drive amount of the cooling fan, and an electrolytic capacitor whose life varies according to the drive amount of the cooling fan. The cooling fan control unit controls the drive amount based on the relationship between the drive amount, the life of the cooling fan, and the life of the electrolytic capacitor.

Abstract: A transistor chip formed from a wide band gap semiconductor, on which transistor elements for an upper arm are formed is mounted on a front surface of an insulating substrate. A transistor chip formed from a wide band gap semiconductor, on which transistor elements for a lower arm are formed is mounted on a rear surface of the insulating substrate.

Abstract: A CR snubber circuit capable of increasing a reduction effect of the effective inductance component and suppressing a ringing component generated at the time of switching the switching element is obtained. A first current path formed on one surface of the substrate and a second current path formed on the other surface, which is the opposite side of the one surface of the substrate, are opposed to each other with the substrate being sandwiched therebetween, and the capacitor 5 and the resistor 6 are arranged such that current flows in opposite directions in the first current path and the second current path, and a band elimination filter is formed by the capacitor 5, the resistor 6, and an effective inductance component obtained by coupling an inductance component included in the first current path and an inductance component included in the second current path.

Abstract: A CR snubber circuit capable of increasing a reduction effect of the effective inductance component and suppressing a ringing component generated at the time of switching the switching element is obtained. A first current path formed on one surface of the substrate and a second current path formed on the other surface, which is the opposite side of the one surface of the substrate, are opposed to each other with the substrate being sandwiched therebetween, and the capacitor 5 and the resistor 6 are arranged such that current flows in opposite directions in the first current path and the second current path, and a band elimination filter is formed by the capacitor 5, the register 6, and an effective inductance component obtained by coupling an inductance component included in the first current path and an inductance component included in the second current path.

Abstract: A gate drive circuit for driving an IGBT serving as a power semiconductor device includes a constant-current gate drive circuit that charges a gate capacity of the IGBT at a constant current, and a constant-voltage gate drive circuit that is connected in parallel to the constant-current gate drive circuit between input and output terminals thereof via a series circuit constituted by a MOSFET and a resistor, and charges the gate capacity of the IGBT at a constant voltage, wherein the gate drive circuit charges the gate capacity of the IGBT using both the constant-current gate drive circuit and the constant-voltage gate drive circuit at the time of driving the IGBT.

Abstract: An inverter that drives a motor and a noise filter are arranged on a surface of a motor housing, and the inverter and the noise filter are integrated with the motor housing. The noise filter reduces a common-mode current generated by a switching operation of the inverter to flow out to a side of a three-phase power supply through the motor housing.

Abstract: A gate drive circuit for driving an IGBT serving as a power semiconductor device includes a constant-current gate drive circuit that charges a gate capacity of the IGBT at a constant current, and a constant-voltage gate drive circuit that is connected in parallel to the constant-current gate drive circuit between input and output terminals thereof via a series circuit constituted by a MOSFET and a resistor, and charges the gate capacity of the IGBT at a constant voltage, wherein the gate drive circuit charges the gate capacity of the IGBT using both the constant-current gate drive circuit and the constant-voltage gate drive circuit at the time of driving the IGBT.

Abstract: An inverter that drives a motor and a noise filter are arranged on a surface of a motor housing, and the inverter and the noise filter are integrated with the motor housing. The noise filter reduces a common-mode current generated by a switching operation of the inverter to flow out to a side of a three-phase power supply through the motor housing.

Abstract: A transistor chip formed from a wide band gap semiconductor, on which transistor elements for an upper arm are formed is mounted on a front surface of an insulating substrate. A transistor chip formed from a wide band gap semiconductor, on which transistor elements for a lower arm are formed is mounted on a rear surface of the insulating substrate.

Abstract: A power conversion apparatus and its control method is disclosed in which a main circuit and its control circuit are simplified by allowing part of the main circuit to be shared by a converter section and an inverter section. The power conversion apparatus comprises a converter section 120 and an inverter section 130, each having upper and lower arm switch sections, and a common section 110 also having upper and lower arm switch sections. One phase of an AC input power terminal is connected to one phase of an AC output power terminal. The common phase is also connected to a connection point 1RU of the upper and lower arm switch sections of the common section. The remaining phases of the AC input terminals are connected to connecting points of upper and lower arm switch sections of the converter section, and the remaining phases of the AC output terminals are connected to connection points of upper and lower arm switch sections of the inverter section.