Abstract: A surge absorbing element includes a varistor substrate, a pair of electrodes that are electrically connected to both end faces of the varistor substrate, respectively, to sandwich the varistor substrate, external leads that electrically connect to the paired electrodes, respectively, exterior members that cover the electrodes, and a thermal expansion body that is provided between the paired electrodes and that irreversibly expands with heat generated by the varistor substrate to separate at least one of the paired electrodes from the varistor substrate. A temperature at which the thermal expansion body starts expanding is, for example, equal to or higher than 180° C.

Abstract: A surge absorbing element includes a varistor substrate, a pair of electrodes that are electrically connected to both end faces of the varistor substrate, respectively, to sandwich the varistor substrate, external leads that electrically connect to the paired electrodes, respectively, exterior members that cover the electrodes, and a thermal expansion body that is provided between the paired electrodes and that irreversibly expands with heat generated by the varistor substrate to separate at least one of the paired electrodes from the varistor substrate. A temperature at which the thermal expansion body starts expanding is, for example, equal to or higher than 180° C.

Abstract: A circuit disconnection element that can open or short-circuit between a power storage element and a step-up/step-down bidirectional chopper circuit is provided in a power storage system, thereby preventing a self-discharge state in a process of charging. Furthermore, at the time of occurrence of an abnormality, the power storage element is detached from other devices including the step-up/step-down bidirectional chopper circuit. Accordingly, an energy loss of the power storage element at the time of power regeneration can be reduced to improve the energy use efficiency. Further, breakage influences such that the power storage element causes breakage in other devices at the time of occurrence of the abnormality can be prevented, thereby enabling to obtain an AC motor drive device having mounted therein a highly safe power storage system.

Abstract: In the case where DC power from a DC power supply is converted to AC power by an inverter and supplied to an AC motor, a power compensator is connected in parallel with a DC power input portion of the inverter, and a control device of the power compensator charges/discharges a power storage device to perform a power compensation process A when power demand for the AC motor exceeds a predetermined value, and takes into account power allowance which can be inputted and outputted from the DC power supply to the power storage device and performs a power storage adjustment process B of performing auxiliary charge of the power storage device within the range of the power allowance when the power compensation process A is unnecessary.

Abstract: A circuit switching element is provided that switches a step-up/step-down bidirectional chopper circuit, arranged between a DC bus and a power storage element, to a first chopper circuit or to a second chopper circuit, whose step-up and step-down characteristics are in a complementary relation. The first and second chopper circuits are used together at a time of charge and discharge. Accordingly, an AC motor drive device having mounted therein a power storage system is obtained, in which the power storage system can perform charge and discharge to and from the power storage element, regardless of a bus voltage and can increase energy use efficiency.

Abstract: A circuit disconnection element that can open or short-circuit between a power storage element and a step-up/step-down bidirectional chopper circuit is provided in a power storage system, thereby preventing a self-discharge state in a process of charging. Furthermore, at the time of occurrence of an abnormality, the power storage element is detached from other devices including the step-up/step-down bidirectional chopper circuit. Accordingly, an energy loss of the power storage element at the time of power regeneration can be reduced to improve the energy use efficiency. Further, breakage influences such that the power storage element causes breakage in other devices at the time of occurrence of the abnormality can be prevented, thereby enabling to obtain an AC motor drive device having mounted therein a highly safe power storage system.

Abstract: A circuit switching element is provided that switches a step-up/step-down bidirectional chopper circuit, arranged between a DC bus and a power storage element, to a first chopper circuit or to a second chopper circuit, whose step-up and step-down characteristics are in a complementary relation. The first and second chopper circuits are used together at a time of charge and discharge. Accordingly, an AC motor drive device having mounted therein a power storage system is obtained, in which the power storage system can perform charge and discharge to and from the power storage element, regardless of a bus voltage and can increase energy use efficiency.

Abstract: In the case where DC power from a DC power supply is converted to AC power by an inverter and supplied to an AC motor, a power compensator is connected in parallel with a DC power input portion of the inverter, and a control device of the power compensator charges/discharges a power storage device to perform a power compensation process A when power demand for the AC motor exceeds a predetermined value, and takes into account power allowance which can be inputted and outputted from the DC power supply to the power storage device and performs a power storage adjustment process B of performing auxiliary charge of the power storage device within the range of the power allowance when the power compensation process A is unnecessary.