56results about How to "Avoid switching losses" patented technology

DC-DC converters such as flyback converters achieve self-regulation by communication information between primary and secondary circuits through the power transformer. Operating in accordance with a generalized concept or algorithm, the converter can be bi-directional and self-regulating. Control of the turn OFF times of semiconductor switches in first and second circuits coupled to first and second windings of the power transformer determines whether power flow is in one direction through the converter or the other direction. Turn ON timing of each semiconductor switch is when there is a reverse current through the switch and voltage across the switch is at or near zero. Turn OFF of a switch can be controlled from one or more operating parameters of the converter such as output voltage, in which case the converter's self-regulation is affected through duty cycle variation with variations in output voltage.

A fuel cell system includes a fuel cell, a battery, and a DC / DC converter capable of connecting the fuel cell and the battery on a power feeding circuit. A method of starting operation of the fuel cell system includes the steps of connecting a bypass line connected to a battery for bypassing the DC / DC converter to the power feeding circuit, and directly supplying electrical energy from the battery to an air compressor of an oxygen-containing gas supply apparatus through the bypass line in a state where the fuel cell is disconnected from the power feeding circuit.

This control method for a fuel cell vehicle includes: a target motor output power obtaining step which obtains a target motor output power corresponding to an accelerator opening degree; and a high output power control step which controls operations of a first DC-DC converter and a second DC-DC converter, such that an output voltage of a power source becomes equal to or larger than a predetermined voltage that is required for securing a desired motor output power, when the target motor output power is larger than a predetermined output power threshold value.

In order to assure drive of a drive motor, a boost operation of a boost device is appropriately performed by judging whether a voltage supplied from a fuel cell suffices a voltage required for driving the drive motor, thereby suppressing a switching loss by the boost device. A fuel cell system is a power source for driving a load. The system includes: a drive motor driven by an electric power; a fuel cell which generates electricity by an electrochemical reaction between an oxidizing gas containing oxygen and a fuel gas containing hydrogen and supplies an electric power to the drive motor; a first boost device which can boosts the voltage outputted from the fuel cell and supplies the boosted voltage to the drive motor; and boost control means which controls voltage boost performed by the first boost device according to the relationship between the fuel cell output voltage and the voltage required by the drive motor.

In controlling switching elements of a current source inverter, a switching loss in the switching element is prevented according to a normal switching operation for a commutation operation, without requiring any particular control.In the commutation operation of the current source inverter, a timing for driving the switching elements is controlled in such a manner that an overlap period is generated, during when both a switching element at the commutation source and a switching element at the commutation target are set to be the ON state, a resonant circuit is controlled based on the control of the switching elements having this overlap period, and resonant current of the resonant circuit reduces the switching loss upon commutation operation of the switching elements. By controlling the generation of the resonant current of the resonant circuit by using the control of the switching elements having the overlap period, the resonant current generated by this control renders current and voltage of the switching element at the commutation source to zero when commutation is performed, thereby reducing the switching loss in the commutation operation.

A method and device for controlling the n LLM coils of an LLM stator making it possible to change the polarity of the coil voltage of the n LLM coils more easily and with little circuit complexity. It is proposed to apply a first operating potential to n first input terminals of n half bridges, and apply a second operating potential to n second input terminals of the n half bridges. For each half bridge, a first switch is connected between a center point of the respective half bridge and the first input terminal, and a second switch is connected between the center point of the relevant half bridge and the second input terminal. The center point of the n half bridges is connected in each case to n first terminals of then LLM coils, and the second terminals of then LLM coils are connected in a control point that is regulated to a predetermined potential.