An electric drive system for a vehicle may include positive and negative bus rails carrying a direct current (DC) bus voltage, an energy storage system (ESS), a power inverter having a plurality of semiconductor switches operable for inverting the DC bus voltage into an alternating current (AC) bus voltage, and an electric machine. A DC-DC converter may be connected to the bus rails between the capacitor and the power inverter and may include a converter semiconductor switch disposed in the positive bus rail, an inductor coil connected to the positive bus rail and receiving current flowing through the converter semiconductor switch, at least one diode, and a bypass switch connected to the positive bus rail and configured to allow current to bypass the converter. The DC-DC converter may be configured to output a DC bus voltage to the power inverter with a same polarity as the battery polarity.

An electric drive system for a vehicle may include positive and negative bus rails carrying a direct current (DC) bus voltage, an energy storage system (ESS), a power inverter having a plurality of semiconductor switches operable for inverting the DC bus voltage into an alternating current (AC) bus voltage, and an electric machine. A DC-DC converter may be connected to the bus rails between the capacitor and the power inverter and may include a converter semiconductor switch disposed in the positive bus rail, an inductor coil connected to the positive bus rail and receiving current flowing through the converter semiconductor switch, at least one diode, and a bypass switch connected to the positive bus rail and configured to allow current to bypass the converter. The DC-DC converter may be configured to output a DC bus voltage to the power inverter with a same polarity as the battery polarity.

A wireless power transmission apparatus for wirelessly transmitting power to a wireless power reception apparatus according to one embodiment of the present invention may comprise: a first transmission coil; a second transmission coil for transmitting power higher than power transmitted by the first transmission coil; a direct current power conversion unit for receiving direct current power applied thereto and outputting a first voltage and a second voltage higher than the first voltage; and a control unit for selecting one of the first and second voltages on the basis of an operating mode of the wireless power transmission apparatus and required power of the wireless power reception apparatus, and controlling such that power is transmitted through the first or second transmission coil, using the selected voltage.

A wireless power transmission apparatus for wirelessly transmitting power to a wireless power reception apparatus according to one embodiment of the present invention may comprise: a first transmission coil; a second transmission coil for transmitting power higher than power transmitted by the first transmission coil; a direct current power conversion unit for receiving direct current power applied thereto and outputting a first voltage and a second voltage higher than the first voltage; and a control unit for selecting one of the first and second voltages on the basis of an operating mode of the wireless power transmission apparatus and required power of the wireless power reception apparatus, and controlling such that power is transmitted through the first or second transmission coil, using the selected voltage.

In a power converter including a plurality of switches, a plurality of freewheeling diodes each electrically connected in anti-parallel with a respective one of the switches, a freewheeling current input electrically connected to an output terminal of each of the switches, and a freewheeling current output electrically connected to an input terminal of each of the switches, a plurality of freewheeling current paths are defined, each of which is an electrical path passing through a respective one of the freewheeling diodes from the freewheeling current input to the freewheeling current output. At least one of the freewheeling current paths is a maximum path having a maximum impedance among the freewheeling current paths. A voltage drop across the freewheeling diode included in the maximum path is less than a voltage drop across each of the other freewheeling diodes when a freewheeling current flows through each of the plurality of freewheeling diodes.

In a power converter including a plurality of switches, a plurality of freewheeling diodes each electrically connected in anti-parallel with a respective one of the switches, a freewheeling current input electrically connected to an output terminal of each of the switches, and a freewheeling current output electrically connected to an input terminal of each of the switches, a plurality of freewheeling current paths are defined, each of which is an electrical path passing through a respective one of the freewheeling diodes from the freewheeling current input to the freewheeling current output. At least one of the freewheeling current paths is a maximum path having a maximum impedance among the freewheeling current paths. A voltage drop across the freewheeling diode included in the maximum path is less than a voltage drop across each of the other freewheeling diodes when a freewheeling current flows through each of the plurality of freewheeling diodes.

An energy storage system stores potential energy and providing a regulated output of electrical energy for powering an electrical load. The system includes an array of storage capacitors including a plurality of storage capacitors coupled in series. A balance control device balances the voltage on each of the storage capacitors in the array. An input control device manages the input for charging the storage capacitor array. An output power supply has an input coupled to the storage capacitor array and provides regulated power to an electrical load. A power monitor device electrically decouples the storage capacitor array from the electrical load when the total voltage of the storage capacitor array falls below a preset minimum level.

An energy storage system stores potential energy and providing a regulated output of electrical energy for powering an electrical load. The system includes an array of storage capacitors including a plurality of storage capacitors coupled in series. A balance control device balances the voltage on each of the storage capacitors in the array. An input control device manages the input for charging the storage capacitor array. An output power supply has an input coupled to the storage capacitor array and provides regulated power to an electrical load. A power monitor device electrically decouples the storage capacitor array from the electrical load when the total voltage of the storage capacitor array falls below a preset minimum level.

To provide a power supply circuit for fiber laser oscillator use capable of reducing the size of a fiber laser oscillator. A power supply circuit for fiber laser oscillator use comprises: a rectifier circuit unit capable of receiving input of a voltage having a particular value; and a power supply unit to which the rectifier circuit unit is connected. The rectifier circuit unit is one rectifier circuit unit selectable from multiple rectifier circuit units capable of receiving inputs of voltages having different values. Each of the rectifier circuit units includes a power factor correction circuit for adjusting a power factor at 1.

A DC link capacitor in a drive system for an electric vehicle is quickly discharged using only local action within an inverter module and without any extra components to dissipate the charge. The inverter has a phase leg comprising an upper switching device and a lower switching device coupled across the capacitor. A gate driver is coupled to the phase leg to alternately switch the switching devices to ON state according to a PWM signal during pulse-width modulation of the drive system. The gate driver is configured to discharge the link capacitor during a discharge event by simultaneously activating the upper and lower switching devices to transitional states. Thus use of transitional states ensures that the switching devices provide an impedance that dissipates the capacitor charge while protecting the devices from excessive temperature.