A direct-current bus power supply as a power supply device supplies power to a load capable of switching a state between a driving state in which driving is performed by receiving power supply and a standby state in which driving is stopped while receiving power supply. The power supply device includes: a diode bridge circuit and capacitors as a rectifier circuit that enables an alternating-current voltage to be rectified by respective rectification systems of full-wave rectification and voltage doubler rectification; and a switching unit that perform switching between the full-wave rectification and the voltage doubler rectification on the basis of a voltage value of the alternating-current voltage and the state of the load.

A converter circuit converts AC electric power into DC power. An inverter circuit converts the DC power into AC power. A capacitor is connected in parallel to each of the converter circuit and the inverter circuit between these circuits. The capacitor allows variation of an output voltage from the converter circuit, and absorbs variation of an output voltage from the inverter circuit due to a switching operation. An overvoltage protection circuit includes a resistor and a semiconductor element connected in series to each other. The overvoltage protection circuit is connected in parallel to the capacitor to protect the inverter circuit from an overvoltage. First and second control units respectively control the inverter circuit and the overvoltage protection circuit.

Systems and methods for switching between a power supply mode and an electronic load mode are disclosed. For switching from the power supply mode to the electronic load mode, the method comprises the steps of: deactivating a power element; activating a current control module and a phase-locked loop to obtain a voltage phase of a device under test; calculating a turn-on amount of the power element according to a current setting value and the voltage phase; and causing the power element to generate a load current for the device under test. For switching from the electronic load mode to the power supply mode, the method comprises the steps of: deactivating the power element; activating a voltage control module; calculating the turn-on amount of the power element according to a voltage setting value; and causing the power element to input a corresponding voltage to the device under test.

Systems and methods for switching between a power supply mode and an electronic load mode are disclosed. For switching from the power supply mode to the electronic load mode, the method comprises the steps of: deactivating a power element; activating a current control module and a phase-locked loop to obtain a voltage phase of a device under test; calculating a turn-on amount of the power element according to a current setting value and the voltage phase; and causing the power element to generate a load current for the device under test. For switching from the electronic load mode to the power supply mode, the method comprises the steps of: deactivating the power element; activating a voltage control module; calculating the turn-on amount of the power element according to a voltage setting value; and causing the power element to input a corresponding voltage to the device under test.

An adaptive direct current (DC) conversion system may include a multi-mode DC converter circuit including two or more power switches, where the multi-mode DC converter circuit is operable in two or more pulse width modulation (PWM) modes based on two or more PWM signal sets provided to the two or more power switches. The system may further include a PWM controller, where the PWM controller controls which of the two or more PWM modes the multi-mode DC converter circuit operates in by providing the multi-mode DC converter circuit with the associated one of the two or more PWM signal sets.

In a system for feeding a DC link and a method for operating the system, a sensor for detecting a current in the DC link or voltage on the DC link is connected to a controller, which activates a second converter, e.g., a DC/DC converter or current controller. A first energy storage device is connected via the second converter to the DC link, and the controller activates a third converter, e.g., a DC/DC converter or current controller. A second energy storage device is connected via the third converter to the DC link, and the first and the second energy storage devices are different, e.g., have a different dynamic behavior and/or different discharge time constants.

The invention relates to a control apparatus for a refrigerator compressor having at least one two-phase AC asynchronous motor (K1, K2), having mains connection means (10) for connection to a preferably public voltage supply network which nominally provides a mains AC voltage of between 85 V and 264 V, in particular between 100 V and 230 V, first voltage converter means (14) which are connected downstream of the mains connection means and are intended to generate an intermediate voltage, in particular an intermediate DC voltage, from the mains AC voltage, second voltage converter means (16-1, 16-2) which are connected downstream of the first voltage converter means and are intended to generate an output signal which is independent of a level and a mains frequency of the mains AC voltage, in particular has a constant voltage and/or frequency in periods, and is intended to control the refrigerator compressor with an AC voltage of a plurality of differently predefinable voltage levels, wherein the mains connection means are assigned voltage detector means (12) for capturing the mains AC voltage, the detector output signal from which can be evaluated by the second voltage converter means or control means (24) assigned to the latter for the purpose of generating a mains-voltage-dependent maximum value for a current of the output signal.

The invention relates to a control apparatus for a refrigerator compressor having at least one two-phase AC asynchronous motor (K1, K2), having mains connection means (10) for connection to a preferably public voltage supply network which nominally provides a mains AC voltage of between 85 V and 264 V, in particular between 100 V and 230 V, first voltage converter means (14) which are connected downstream of the mains connection means and are intended to generate an intermediate voltage, in particular an intermediate DC voltage, from the mains AC voltage, second voltage converter means (16-1, 16-2) which are connected downstream of the first voltage converter means and are intended to generate an output signal which is independent of a level and a mains frequency of the mains AC voltage, in particular has a constant voltage and/or frequency in periods, and is intended to control the refrigerator compressor with an AC voltage of a plurality of differently predefinable voltage levels, wherein the mains connection means are assigned voltage detector means (12) for capturing the mains AC voltage, the detector output signal from which can be evaluated by the second voltage converter means or control means (24) assigned to the latter for the purpose of generating a mains-voltage-dependent maximum value for a current of the output signal.

The present invention relates to a method for determining an insulation resistance and for locating insulation faults in a power supply system whose active parts are ungrounded and which is supplied via a converter operated grounded and equipped with controlled power semiconductor switches. A common-mode voltage against ground is generated at the output of the converter and is superimposed on the ungrounded network as an active measuring voltage in order to measure the insulation resistance. The direct integration of the generation of the common-mode measuring voltage in the converter allows cost-effective implementation including similarly comprehensive insulation monitoring functions as those possible in fully ungrounded power supply systems. Furthermore, the method for determining the insulation resistance can be expanded into a method for locating insulation faults and thus for locating faulty system branches.

A power-conversion device and a ground-fault-location-diagnosis method for determining ground-fault locations on a motor and a cable are disclosed. The power-conversion device includes a ground-fault-current-measurement unit, an interphase short-circuit current-measurement unit, and a ground-fault-location-determination unit. The ground-fault-current-measurement unit turns on all switches of either upper arms or lower arms of three half-bridge circuits, and measures output current values of a plurality of phases generated during the ON period. The interphase short-circuit-current-measurement unit turns on a switch of an upper arm of one phase of the three half-bridge circuits and a switch of a lower arm of a phase different from the one phase, and measures output current values of a plurality of phases generated during a period of time both switches are ON. The ground-fault-location-determination unit determines a ground-fault location based on output-current values measured by the ground-fault-current-measurement unit and the output-current values measured by the interphase short-circuit current-measurement unit.