An apparatus for controlling an AC power supply for an electric motor, said AC power supply being derived from a DC voltage. The apparatus including a comparer configured to provide a comparison of a modulation index of a motor control signal with a reference value. This current data provider is configured to provide current data based on a torque demand signal; a speed signal indicating the speed of rotation of the AC motor; and an indication of the DC voltage modified on the comparison for control of the motor control signal which is based on the motor current data.

A first offset voltage which is added to voltage commands in a first three-phase voltage command calculated on the basis of a control command for an AC rotary machine, and a second offset voltage which is added to voltage commands in a second three-phase voltage command calculated on the basis of a control command for the AC rotary machine, are set in such a manner that a period during which one of a first power converter and a second power converter outputs an effective vector and the other thereof outputs a zero vector occurs during a carrier period of a first carrier wave signal and a second carrier wave signal.

A first offset voltage which is added to voltage commands in a first three-phase voltage command calculated on the basis of a control command for an AC rotary machine, and a second offset voltage which is added to voltage commands in a second three-phase voltage command calculated on the basis of a control command for the AC rotary machine, are set in such a manner that a period during which one of a first power converter and a second power converter outputs an effective vector and the other thereof outputs a zero vector occurs during a carrier period of a first carrier wave signal and a second carrier wave signal.

Provided is an electric drive device which controls a current supplied to coils during normal operation so as to be less than a current limit value when normal, which is determined from heat generating properties and heat radiating properties of a thermally coupled body that includes the coils and an inverter circuit. When an abnormality in each group or each phase of the coils and the inverter circuit is detected, the supply of current to all phases of a group suffering an abnormality in the coils, or to a phase that is not capable of continuous operation, is stopped or reduced; and the limit value of the current supplied to a coil that is capable of continuous operation is reset to a current limit value in the event of abnormality, which is larger than the current limit value when normal, within the range of improvement of the heat generating properties of the thermally coupled body due to the stopping or reduction of the supply of current.

Provided is an electric drive device which controls a current supplied to coils during normal operation so as to be less than a current limit value when normal, which is determined from heat generating properties and heat radiating properties of a thermally coupled body that includes the coils and an inverter circuit. When an abnormality in each group or each phase of the coils and the inverter circuit is detected, the supply of current to all phases of a group suffering an abnormality in the coils, or to a phase that is not capable of continuous operation, is stopped or reduced; and the limit value of the current supplied to a coil that is capable of continuous operation is reset to a current limit value in the event of abnormality, which is larger than the current limit value when normal, within the range of improvement of the heat generating properties of the thermally coupled body due to the stopping or reduction of the supply of current.

A semiconductor device includes a semiconductor chip made of a SiC substrate and having main electrodes on one surface and a rear surface, first and second heat sinks, respectively, disposed adjacent to the one surface and the rear surface, a terminal member interposed between the second heat sink and the semiconductor chip, and a plurality of bonding members disposed between the main electrodes, the first and second heat sinks, and the terminal member. The terminal member includes plural types of metal layers symmetrically layered in the plate thickness direction. The terminal member as a whole has a coefficient of linear expansion at least in a direction orthogonal to the plate thickness direction in a range larger than that of the semiconductor chip and smaller than that of the second heat sink.

A motor drive apparatus includes a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor, and a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm, and to control the power converter. The drive controller is configured to control the power converter by switching a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and a second mode in which a second correction value smaller than the first correction value is employed to control the power converter.

A motor drive apparatus includes a power converter including an inverter having an upper arm and a lower arm, the inverter being configured to control an operation of an electric motor, and a drive controller configured to apply a dead time for preventing a short circuit between the upper arm and the lower arm, and to control the power converter. The drive controller is configured to control the power converter by switching a first mode in which a first correction value representing a time used to correct a voltage drop due to the dead time is employed to control the power converter, and a second mode in which a second correction value smaller than the first correction value is employed to control the power converter.

A semiconductor device includes a metal member, a first semiconductor chip, a second semiconductor chip, a first solder and a second solder. A quantity of heat generated in the first semiconductor chip is greater than the second semiconductor chip. The second semiconductor chip is formed of a material having larger Young's modulus than the first semiconductor chip. The first semiconductor chip has a first metal layer connected to the metal member through a first solder at a surface facing the metal member. The second semiconductor chip has a second metal layer connected to the metal member through a second solder at a surface facing the metal member. A thickness of the second solder is greater than a maximum thickness of the first solder at least at a portion of the second solder corresponding to a part of an outer peripheral edge of the second metal layer.

Embodiments relate to a motor driving system comprising a power network between an inverter and a motor and a method for designing such motor drive system, the motor drive system comprising: an AC motor; an inverter unit for applying a voltage to the AC motor; a controller configured for controlling an output voltage of the inverter unit; and a power network circuit disposed between the inverter unit and the AC motor, wherein the power network circuit is configured with passive element.