A power system circuit apparatus is provided, which includes a first transformer having a Y-Y connection structure and configured to receive and transform three-phase AC power and output the transformed result, a first controlled rectifier configured to rectify an output voltage of the first transformer and output the rectified result; a second transformer having a Y-delta connection structure and configured to receive and transform the three-phase AC power and output the transformed result; a second controlled rectifier configured to rectify an output voltage of the second transformer and output the rectified result; and an output unit configured to add the output of the first controlled rectifier and the output of the second controlled rectifier and output a resultant sum. Accordingly, there is an effect of reducing the output current ripple and thus reducing the loss compared to the related method.

A converter controller configured to control a firing phase of a converter includes an integral element integrating a deviation of DC current from a current command value and generates a voltage command value of output voltage of the converter by performing control calculation of the deviation. In a first mode of performing commutation of an inverter by intermittently setting DC current to zero, the converter controller sets DC current to zero for a predetermined pause time by narrowing a phase control angle simultaneously with a commutation command for the inverter. When the control calculation is resumed immediately after the pause time, the converter controller uses a control amount calculated in control calculation immediately before the pause time as a preset value of the integral element immediately after the pause time.

A power converter and an air conditioner having the same, in which the power converter includes a rectifying unit configured to rectify an input AC current and an interleave converter that has a plurality of converters and that is configured to convert rectified output from the rectifying unit to DC power and output the converted DC power. The power converter also includes a capacitor connected to an output terminal of the interleave converter, and a converter controller configured to control the interleave converter. The converter controller controls the interleave converter by calculating a load level of both terminals of the capacitor and changing a number of operating converters in the plurality of converters of the interleave converter based on the determined load level of both terminals of the capacitor.

An electrical circuit for charging a DC voltage source from an AC voltage network. The circuit includes an input that is able to receive an AC voltage from the voltage network, and a first output able to be connected to the DC voltage source. An insulating stage formed using a plurality of capacitors is arranged so as to electrically insulate the input from the first output of the circuit. A frequency-raising stage is arranged between the input of the circuit and the insulating stage so that the capacitors of the insulating stage are in a circuit portion that has flowing through it an AC current at a frequency that is greater than that of the AC network.

In the field of line commutated converters, for use in high voltage direct current (HVDC) power transmission, a line commutated converter comprises a plurality of converter limbs that extend between first and second DC terminals. Each converter limb includes first and second limb portions which are separated by an AC terminal. The first limb portions together define a first limb portion group and the second limb portions together define a second limb portion group. Each limb portion includes at least one switching element that is configured to turn on and conduct current when it is forward biased and it receives a turn on signal and to naturally turn off and no longer conduct current when it is reverse biased and the current flowing through it falls to zero. The converter also includes a control unit.

A converter controller configured to control a firing phase of a converter includes an integral element integrating a deviation of DC current from a current command value and generates a voltage command value of output voltage of the converter by performing control calculation of the deviation. In a first mode of performing commutation of an inverter by intermittently setting DC current to zero, the converter controller sets DC current to zero for a predetermined pause time by narrowing a phase control angle simultaneously with a commutation command for the inverter. When the control calculation is resumed immediately after the pause time, the converter controller uses a control amount calculated in control calculation immediately before the pause time as a preset value of the integral element immediately after the pause time.

A DC power transmission system interconnects a plurality of AC systems via a DC line. A plurality of power conversion devices are connected between the plurality of AC systems and the DC line. One of the plurality of power conversion devices controls the voltage on the DC line, while the remaining power conversion device controls a current input and output to and from the DC line. In a restart which resumes power conversion from a stopped state for controlling a DC current on the DC line, the power conversion device performing current control monitors the voltage on the DC line and starts a restart operation without transmitting or receiving information to or from the other power conversion device.

A converter assembly (10; 60) comprises a converter (12; 62) for interconnecting first and second electrical networks (14, 18). The converter (12; 62) includes at least one control module (22) that is programmed to control directly in accordance with a control program stored therein the switching of one or more switches (24) in a switching module (26) of the converter (12; 62). The converter (12; 62) also includes at least one energy storage device(28)which is configured to store energy to at least in part supply power to at least one corresponding control module (22). The converter assembly (10; 60) additionally includes a high-level controller (48) which is arranged in communication with the converter (12; 62) and the or each control module (22) therein. The high-level controller (48) is programmed to transition the converter (12; 62) from an on-line condition to an off-line condition during which transition the or each energy storage device (28) within the converter (12; 62) discharges the energy stored therein. The high-level controller (48) is also further programmed to replace the control program of at least one control module (22) of the converter (12; 62) during the said transition from an on-line condition to an off-line condition.

In the field of line commutated converters, for use in high voltage direct current (HVDC) power transmission, a line commutated converter (10) comprises a plurality of converter limbs (12A, 12B, 12C) that extend between first and second DC terminals (16, 18). Each converter limb (12A, 12B, 12C) includes first and second limb portions (22, 24) which are separated by an AC terminal (26A, 26B, 26C). The first limb portions (22) together define a first limb portion group (28) and the second limb portions (24) together define a second limb portion group (30). Each limb portion (22, 24) includes at least one switching element (36, 36 2, 36 3, 36 4, 36, 36 6) that is configured to turn on and conduct current when it is forward biased and it receives a turn on signal and to naturally turn off and no longer conduct current when it is reverse biased and the current flowing through it falls to zero. The converter (10) also includes a control unit (38) which is programmed to, in use, control successive switching of the switching elements (36, 36 2, 36 3, 36 4, 36, 36 6) whereby a first switching element (36) in the first limb portion group (28) and a second switching element (36 2) in the second limb portion group (30) and a different converter limb (12B, 12C) to the first switching element (36) connect two corresponding AC terminals (26A, 26C in series between the first and second DC terminals (16, 18). The control unit (38) is further programmed to send a third switching element (36 3) in the first limb portion group (28) a turn on signal whereby the third switching element (36 3) turns on and begins to conduct current while the current flowing through the first switching element (36) begins to fall to zero and the first switching element (36) prepares to naturally turn off, and to subsequently send a fourth switching element (36 4) in the second limb portion group (30) and a different converter limb (12A, 12C) to the third switching element (36 3) a turn on signal whereby the fourth switching element turns (36 4) on and begins to conduct current while the current flowing through the second switching element (36 2) begins to fall to zero and the second switching element (36 2) prepares to naturally turn off. The control unit (38) also checks for an abnormal current flow (56) associated with the first switching element (36) during a fini

A method for controlling a three-phase electrical converter comprises: selecting a three-phase optimized pulse pattern from a table of pre-computed optimized pulse patterns based on a reference flux; determining a two-component optimal flux from the optimized pulse pattern and determine a one-component optimal third variable; determining a two-component flux error from a difference of the optimal flux and an estimated flux estimated based on measurements in the electrical converter; determining a one-component third variable error from a difference of the optimal third variable and an estimated third variable; modifying the optimized pulse pattern by time-shifting switching instants of the optimized pulse pattern such that a cost function depending on the time-shifts is minimized, wherein the cost function comprises a flux error term and a third variable error term, wherein the flux error term is based on a difference of the flux error and a flux correction function providing a flux correction based on the time-shifts and the third variable error term is based on a difference of the third variable error and a third variable correction function providing a third variable correction based on the time-shifts; and applying the modified optimized pulse pattern to the electrical converter.