In a drive circuit, a rate adjuster adjusts a charging speed of a MOSFET to be faster than the charging speed of an IGBT when a drive state changer changes the first switching element from the off state to the on state first, and changes the second switching element from the off state to the on state next. The rate adjuster also adjusts a discharging speed of the MOSFET to be faster than the discharging speed of the IGBT when the drive state changer changes the MOSFET from the on state to the off state first, and changes the IGBT from the on state to the off state next.

A power conversion circuit is mounted in a vehicle and controls an output torque of the rotating machine based on a requested command torque. A driving apparatus of a switching element controls a current flowing to the rotating machine. The driving apparatus sets at least one of a turn-on speed and a turn-off speed for the switching element to a plurality of switching speeds that are discretely determined, based on a parameter that is correlated with the output torque and has a controllable value. The driving apparatus turns on or off the switching element at the switching speeds. The switching speeds are allocated to the respective magnitudes of the parameter at uneven intervals, and determined such that the number of allocated switching speeds is greater in a range in which an occurrence frequency of the parameter is high, compared to a range in which the occurrence frequency is low.

A method of operating an inverter including the steps of detecting the temperature of the at least one electrolytic capacitor; selecting at least one of a plurality of switching patterns based on the temperature of the at least one electrolytic capacitor; and generating a ripple current across the at least one electrolytic capacitor by operating the inverter from the at least one of the plurality of switching patterns for preheating of the at least one electrolytic capacitor.

A combination switch includes an Insulated Gate Bipolar Transistor (IGBT), an anti-parallel diode, and a saturable inductor. The diode and inductor are coupled in series between a collector and an emitter of the IGBT. The inductor is fashioned so that it will come out of saturation when a forward bias current flow through the diode falls below a saturation current level. When the diode current falls (for example, due to another combination switch of a phase leg turning on), the diode current initially falls at a high rate until the inductor current drops to the saturation current level. Thereafter, the diode current falls at a lower rate. The lower rate allows the diode current to have a soft landing to zero current, thereby eliminating or reducing voltage and/or current spikes that would otherwise occur. Multiple methods of implementing and manufacturing the saturable inductor are disclosed.

Power converters, and microgrids driven by such a power converter, in which the converter is controlled by a proportional controller which operates directly on AC waveforms, preferably without conversion to a DC type signal; preferably with use of voltage compensation to remove inherent error of proportional controller; and preferably with use of individual phase RMS voltages in the voltage compensation, to allow for normal operation under any load condition. Undervoltage of one or two phases is automatically compensated by adjusting the voltage of all phases, to retain balance. Line-starting of a motor load is automatically detected, and frequency droop is driven, apart from the other control relations in the system, to complete the line-starting operation as quickly as possible.

To include a carrier-wave generation unit to generate a first carrier wave with a frequency higher than a modulation wave, and a second carrier wave with a frequency lower than the first carrier wave, a comparison unit to compare either the first carrier wave or the second carrier wave to the modulation wave in order to generate a switching signal. The carrier-wave generation unit outputs the second carrier wave when a modulation factor is lower than a threshold value, and outputs the first carrier wave when the modulation factor is equal to or higher than the threshold value. When the modulation factor is equal to or higher than the threshold value, a power conversion unit operates in an overmodulation mode, in which the switching operation is stopped during a period longer than one cycle of the second carrier wave.

An electric power conversion device includes: a converter circuit which includes a boost chopper; a capacitor which is connected between output terminals of the converter circuit; a boost chopper which boosts a terminal voltage of the capacitor; a multiphase inverter circuit; and a boost chopper controller. In a case where the operation of the boost chopper is continuously stopped, the capacitor has a capacitance allowing the terminal voltage of the capacitor to have a pulse frequency twice as high as that of the AC power source. The multiphase inverter circuit has an output power which is allowed to fluctuate in synchronization with a power source.

A motor drive apparatus driving a motor as a three-phase motor converting direct current into three-phase alternating current, includes: inverter modules and equivalent in number to phases of the motor; and a control unit generating PWM signals used to drive the inverter modules with PWM. The inverter modules each include a plurality of switching element pairs connected in parallel, each of the switching element pairs including two switching elements connected in series.

A vehicle powertrain includes an IGBT that conducts current between a supply and load. The vehicle powertrain also includes a controller that applies voltage to a gate of the IGBT at a first level for a first duration that depends on a capacitance of the gate, and increases the voltage over a second duration based on a rate of change of the current falling below a threshold defined by a supply voltage for the load.

A temperature regulating device regulates temperature of the magnetic circuit component incorporated in a power converter and including a magnetic core and a coil wound around the magnetic core and includes a cooling device that cools the magnetic circuit component, a temperature estimation device that estimates a temperature of the magnetic circuit component, a target temperature determination device that determines a target temperature of the magnetic circuit component, at which a loss of the magnetic circuit component is lowered, based on a relationship between temperature and loss of the magnetic circuit component, and a cooling suppressor that, when the temperature of the magnetic circuit component estimated by the temperature estimation device is equal to or lower than a predetermined temperature lower than the target temperature, suppresses the cooling of the magnetic circuit component by the cooling device so that the temperature of the magnetic circuit component reaches the target temperature.