A two-stage power converter can incorporate a buck pre-regulator and a resonant bus converter. Such a converter may be operated to achieve unconditional soft switching operation (zero voltage switching a/k/a ZVS) over a wide input and output range, while delivering excellent power conversion efficiency at lower power levels and in a no load condition.

A driving circuit for driving a piezoelectric load, can include: a rechargeable power supply; a power stage circuit coupled between the rechargeable power supply and the piezoelectric load; where during a first operation interval of an operation period, the rechargeable power supply charges the piezoelectric load through the power stage circuit, such that a power supply voltage signal provided to the piezoelectric load in the first operation interval corresponds to a reference voltage in a first interval; and where during a second operation interval of the operation period, the piezoelectric load charges the rechargeable power supply through the power stage circuit, such that the power supply voltage signal in the second operation interval corresponds to the reference voltage in a second interval.

A control method of a power converter including a first stage converter and a second stage converter is provided. The first stage converter converts an input voltage into an intermediate voltage. The second stage converter converts the intermediate voltage into an output voltage to power a load. If a loading amount of the load is larger than a first threshold value, the intermediate voltage is adjusted to increase a voltage difference between the intermediate voltage and the output voltage, so that a change of the intermediate voltage is in a negative correlation with a change of the loading amount. If the loading amount is smaller than a second threshold value, the intermediate voltage remains be unchanged or the intermediate voltage is adjusted, so that the change of the intermediate voltage is in positive correlation with the change of the loading amount.

An energy efficient apparatus includes a switching device, a frequency dependent reactive device, and a control element is provided. The switching device is coupled to a source of electrical power and includes a pair of transistors and is adapted to receive a control signal and to produce an alternating current power signal. The frequency of the alternating current power signal is responsive to the control signal. The frequency dependent reactive device is electrically coupled to the pair of transistors for receiving the alternating current power signal and producing an output power signal. The frequency dependent reactive device is chosen to achieve a desired voltage of the output power signal relative to the frequency of the alternating current power signal. The control element senses an actual voltage of the direct current power signal and modifies the control signal delivered to achieve the desired voltage of the direct current power signal.

A power conversion system including a power conversion unit, a power circuit and a precharge circuit is provided. The power conversion circuit includes an input port, an output port, switching power conversion units and at least one storage device. The storage device is connected between the input and output ports in series. The power circuit is electrically connected to the power conversion circuit for receiving the input voltage and outputting a supply voltage to the power conversion circuit, and the power circuit includes a magnetic element. The precharge circuit precharges the storage device. The precharge circuit includes a winding and a rectifier filter circuit connected to each other. The winding is coupled to the magnetic element for receiving a conversion voltage. The rectifier filter circuit is electrically connected to the storage device so as to receive the conversion voltage and output a charge voltage to the corresponding storage device.

A two-stage power converter can incorporate a buck pre-regulator and a resonant bus converter. Such a converter may be operated to achieve unconditional soft switching operation (zero voltage switching a/k/a ZVS) over a wide input and output range, while delivering excellent power conversion efficiency at lower power levels and in a no load condition.

A driving circuit for driving a piezoelectric load, can include: a rechargeable power supply; a power stage circuit coupled between the rechargeable power supply and the piezoelectric load; where during a first operation interval of an operation period, the rechargeable power supply charges the piezoelectric load through the power stage circuit, such that a power supply voltage signal provided to the piezoelectric load in the first operation interval corresponds to a reference voltage in a first interval; and where during a second operation interval of the operation period, the piezoelectric load charges the rechargeable power supply through the power stage circuit, such that the power supply voltage signal in the second operation interval corresponds to the reference voltage in a second interval.

The instant disclosure concerns a power converter including a capacitor having first and second electrodes respectively coupled to first and second input terminals via a current-limiting element; at least one normally-on transistor; a circuit for powering a circuit for controlling the normally-on transistor; and a switch configurable to, in a first configuration, couple first and second input terminals of the power supply circuit, respectively to the first and second input terminals of the converter, upstream of the current-limiting element and, in a second configuration, connect the first and second input terminals of the power supply circuit respectively to the first and second electrodes of the capacitor, downstream of the current-limiting element.

The invention provides a power supply device and a charged particle beam device capable of reducing noise generated between a plurality of voltages. The charged particle beam device includes a charged particle gun configured to emit a charged particle beam, a stage on which a sample is to be placed, and a power supply circuit configured to generate a first voltage and a second voltage that determine energy of the charged particle beam and supply the first voltage to the charged particle gun. The power supply circuit includes a first booster circuit configured to generate the first voltage, a second booster circuit configured to generate the second voltage, and a switching control circuit configured to perform switching control of the first booster circuit and the second booster circuit using common switch signals.

A power supply circuit has a push-pull portion having a transformer; first and second terminals of the primary winding, each connected to ground via first and second switches; an inductor connected between an input voltage and the primary winding centre tap via a third switch; an energy storage portion connected between the primary winding and ground, and to the inductor via a fourth switch; a controller arranged to monitor the input voltage and to apply partially overlapping first and second PWM signals to the first and second switches; when input voltage is between first and second thresholds, the controller closes the third switch and opens the fourth switch; above the second threshold, the controller applies a third PWM signal to the third switch and opens the fourth switch; and below the first threshold, the controller closes the third switch and applies a fourth PWM signal to the fourth switch.