A switched-mode power controller includes a primary side controller circuit configured in a startup mode of operation to generate a fixed switching frequency pulse width modulation (PWM) signal with incrementing duty-ratio value. The PWM signal drives a main-switch that charges an inductive device with stored energy and discharges the stored energy into a capacitor on a secondary side to generate a power controller output voltage. Based on a comparison of the power controller output voltage with a reference voltage, the primary side controller circuit is configured to stop the incrementing of the duty-ratio of the PWM signal and begin a quasi-resonant mode of operation during which the primary side controller circuit reduces a number of valleys detected in one or more off-times of the main-switch in one or more respective main-switch switching periods.

An apparatus for coupling power systems, in particular a DC system, for example a motor vehicle electrical system, with a single-phase AC system or a further DC system, the apparatus including a non-inverting DC-DC converter and an inverting DC-DC converter, each having a first input and/or output and a second input and/or output, the first input and/or output of the first DC-DC converter being connected in series to a first converter valve to form a first series circuit, and the first input and/or output of the second DC-DC converter being connected in series to a second converter valve to form a second series circuit, the first and second series circuits being connected in parallel, and the second inputs and/or outputs of the DC-DC converters being connected in parallel and the terminals of the parallel circuit of the series circuits being connected to a first input and/or output of the apparatus.

A converter device includes: a power conversion circuit including a reactor and a switching element, rectifying a voltage of alternating-current power supplied from an alternating-current power supply to a direct-current voltage, and boosting and outputting the direct-current voltage; a current detector detecting a current flowing in the reactor; a filter circuit filtering a first signal detected by the current detector; and a control unit generating a control signal on the basis of a carrier and a second signal generated by the filter circuit and controlling, on the basis of the control signal and with a first period, the switching element, the first period being a period of the carrier. The filter circuit cuts off a repetition frequency component in the first period and passes a repetition frequency component in a second period, the second period being longer than the first period.

A converter device includes: a power conversion circuit including a reactor and a switching element, rectifying a voltage of alternating-current power supplied from an alternating-current power supply to a direct-current voltage, and boosting and outputting the direct-current voltage; a current detector detecting a current flowing in the reactor; a filter circuit filtering a first signal detected by the current detector; and a control unit generating a control signal on the basis of a carrier and a second signal generated by the filter circuit and controlling, on the basis of the control signal and with a first period, the switching element, the first period being a period of the carrier. The filter circuit cuts off a repetition frequency component in the first period and passes a repetition frequency component in a second period, the second period being longer than the first period.

An AC capacitor is coupled to a totem-pole type PFC circuit. In response to detection of a power input disconnection, the PFC circuit is controlled to discharge the AC capacitor. The PFC circuit includes a resistor and a first MOSFET and a second MOSFET coupled in series between DC output nodes with a common node coupled to the AC capacitor. When the disconnection event is detected, one of the first and second MOSFETs is turned on to discharge the AC capacitor with a current flowing through the resistor and the turned on MOSFET. Furthermore, a thyristor may be simultaneously turned on, with the discharge current flowing through a series coupling of the MOSFET, resistor and thyristor. Disconnection is detected by detecting a zero-crossing failure of an AC power input voltage or lack of input voltage decrease or input current increase in response to MOSFET turn on for a DC input.

In a switching power supply device, a control circuit controls a first thyristor, a second thyristor, and a switching element according to an input voltage. The control circuit maintains the first thyristor in an on state while maintaining the second thyristor and the switching element in an off state in a first period in which the absolute amplitude value is equal to or less than a first threshold value within the latter half of a first half-cycle of the input voltage at startup, and maintains the second thyristor in an on state while maintaining the first thyristor and the switching element in an off state in a second period in which the absolute amplitude value is equal to or less than a second threshold value within the latter half of a second half-cycle of the input voltage at startup. The second half-cycle is the half-cycle following the first half-cycle.

An AC capacitor is coupled to a totem-pole type PFC circuit. In response to detection of a power input disconnection, the PFC circuit is controlled to discharge the AC capacitor. The PFC circuit includes a resistor and a first MOSFET and a second MOSFET coupled in series between DC output nodes with a common node coupled to the AC capacitor. When the disconnection event is detected, one of the first and second MOSFETs is turned on to discharge the AC capacitor with a current flowing through the resistor and the turned on MOSFET. Furthermore, a thyristor may be simultaneously turned on, with the discharge current flowing through a series coupling of the MOSFET, resistor and thyristor. Disconnection is detected by detecting a zero-crossing failure of an AC power input voltage or lack of input voltage decrease or input current increase in response to MOSFET turn on for a DC input.

The invention relates to a power system with an electric circuit connected between a power grid and a power source. The electric circuit includes a main power converter having main input terminals connected to the power source 16 by a DC link and output terminals. The main power converter is controlled by a controller. The electric circuit includes a main transformer having a primary winding 8a and a secondary winding, the primary winding being connected to the output terminals of the main power converter. Main switchgear is connected between the secondary winding of the main transformer and the power grid. An auxiliary transformer has a primary winding connected to the power grid in parallel with the main switchgear and a secondary winding connected to the controller. A pre-charge circuit is connected between the auxiliary transformer and the DC link.

A direct-current power supply device includes a reactor, a bridge circuit that converts alternating-current voltage output from an alternating-current power supply, which is connected to the reactor, into direct-current voltage, a capacitor that smoothes the output voltage of the bridge circuit, a current detector that detects a first current flowing as an alternating current between the alternating-current power supply and the bridge circuit, a current detector that detects a second current flowing as a direct current between the bridge circuit and the capacitor, an overcurrent determination unit that determines on the basis of a detected first current value whether or not the first current is an overcurrent, and an overcurrent determination unit that determines on the basis of a detected second current value whether or not the second current is an overcurrent. The bridge circuit stops operating when a determination result of either the overcurrent determination unit or the overcurrent determination unit indicates an overcurrent.

A printer system includes a first apparatus including a first voltage source for converting an inputted AC voltage to a first DC voltage and for outputting the converted first DC voltage, and a first controller operable by a voltage based on the first DC voltage outputted from the first voltage source; and a second apparatus including a second voltage source for converting an inputted AC voltage to a second DC voltage and for outputting the converted second DC voltage, and a second controller operable by a voltage based on the first DC voltage outputted from the first voltage source. The second apparatus includes a first switching portion for switching a state thereof between a connection state in which the AC voltage is supplied to the second voltage source and a non-connection state in which supply of the AC voltage is cut off.