Abstract:
It is therefore an objective of the invention to provide an apparatus for conversion between AC power and DC power. The apparatus includes a first power conversion circuit having a first AC side and a first DC side, at least one second power conversion circuit each having a second AC side and a second DC side; and at least one choke having a first terminal, a second terminal and at least one third terminal, wherein the first terminal is arranged to be electrically coupled to a phase of the AC power, and the second terminal and the at least one third terminal are electrically coupled to respective same phases of the first AC side of the first power conversion circuit and the second AC side of the at least one second power conversion circuit. Moreover, the choke includes a first common-mode choke and a first differential-mode choke, wherein: the first common-mode choke and the first differential-mode choke are electrically coupled in series via a first group of coil ends of the first common-mode choke and a first group of coil ends of the first differential-mode choke, and a second group of coil ends of one of the first common-mode choke and the first differential-mode choke are electrically coupled to the first terminal of the choke, and a second group of coil ends of the other are respectively electrically coupled to the second terminal and the at least one third terminal of the choke. The first common-mode choke can help provide high inductance to the high-frequency components of the common-mode current, which flows from the AC power source, since the impedance of the common-mode choke and the differential-mode choke depends on frequency on the same scale as inductance. The advantages of using the common-mode choke is that it provides twice the inductance of separate inductor design due to the coupling effect. Therefore it filters the common-mode current more effectively or the inductance size can be reduced for a given current ripple requirement.
Abstract:
Embodiments of present disclosure relates to a converter. The converter comprises a first conversion unit, a second conversion unit, a switching circuit and a controller. The first conversion unit includes a first voltage source and a second voltage source, and is configured to generate a first voltage from an input voltage. The second conversion unit includes a third voltage source and a fourth voltage source, and is configured to generate a second voltage from the input voltage. The switching circuit is coupled to the first and second conversion units. The controller is coupled to the switching circuit, and is configured to in response to receiving an indication of voltage, cause the switching circuit to couple the first and second conversion units in parallel or in series, cause the first and second voltage sources in series or in parallel, and cause the third and fourth voltage sources in series or in parallel to generate a output voltage.
Abstract:
Disclosed is a DC to DC converter (1). The DC to DC converter includes a first H-bridge converter circuit, a second H-bridge converter circuit sharing a phase leg with the first H-bridge converter circuit, a first rectifier circuit (12), a second rectifier circuit (14), a first transformer (11) and a second transformer (13). The primary winding of the first transformer is connected to the output terminals of the first H-bridge converter circuit, and the secondary winding of the first transformer is connected to the input terminals of the first rectifier circuit. The primary winding of the second transformer is connected to the output terminals of the second H-bridge converter circuit, and the secondary winding of the second transformer is connected to the input terminals of the second rectifier circuit. One of the output terminals of the first rectifier circuit and one of the output terminals of the second rectifier circuit are connected in series. The first rectifier circuit can compensate an insufficient part of the rated output power to provide the output power to a load. Since the first transformer and the second transformer commonly provide power to the load during a power transmitting period, transformers with smaller power level can be used to implement the first transformer and/or the second transformer, thereby the volume of the DC-DC converter being decreased.
Abstract:
A transformer-less static synchronous series compensator for an AC electrical power transmission system having a transmission line carrying an AC current and a method therefor. The transformer-less static synchronous series compensator includes a multiple of voltage source converters (100a, 100b... 100n), each of which having DC input and AC output and being configured to generate an alternating voltage with controllable magnitude and controllable phase angle across the AC output; wherein the AC outputs of the multiple of voltage source converters are configured for parallel-injection of the generated alternating voltages into a phase of the transmission line (A, B, C). The AC transmission line phase current can be distributed to the multiple of inputting the alternating voltages in parallel into the phase of the AC transmission line, and thus the current handling capability requirement for power semiconductor switches used in each of the voltage source converter can be significantly reduced.
Abstract:
It is an objective to provide a power supply cell of a power supply system and a power supply system using the same. The power supply cell includes a first power conversion circuit operative to output a first DC voltage across its first output positive terminal and first output negative terminal, a second power conversion circuit operative to output a second DC voltage across its second output positive terminal and second output negative terminal, a first controllable unidirectional semiconductor switch operative to generate a first conduction path from the first output positive terminal of the first power conversion circuit to the second output negative terminal of the second power conversion circuit, a first unidirectional semiconductor switch operative to generate a second conduction path from the first output positive terminal of the first power conversion circuit to the second output positive terminal of the second power conversion circuit, a second unidirectional semiconductor switch operative to generate a third conduction path from the first output negative terminal of the first power conversion circuit to the second output negative terminal of the second power conversion circuit, a first low-pass filter and a controlling unit operative to issue turn-on signal or turn-off signal to the first controllable unidirectional semiconductor switch so that the first power conversion circuit and the second power conversion circuit supply current to the low-pass filter via the first conduction path or both of the second conduction path and the third conduction path. The first low-pass filter can help smooth the power supply cell's output voltage and current in order to achieve a relatively wide linearly constant output power range. By controlling the ratio of series and parallel connection in a switching cycle of the switching frequency by the switching arrangement, both the output voltage and current range of the power supply cell can be enlarged smoothly and linearly with the help of the first low-pass filter.
Abstract:
an apparatus for conversion between AC power and DC power. The apparatus includes: a first power conversion circuit having a first AC side and a DC side, at least one second power conversion circuit each having a second AC side and sharing the DC side with the first power conversion circuit, and at least one choke having a first terminal, a second terminal and at least one third terminal, wherein: the first terminal is arranged to be electrically coupled to a phase of the AC power, and the second terminal and the at least one third terminal are electrically coupled to respective same phases of the first AC side of the first power conversion circuit and the second AC side of the at least one second power conversion circuit. Moreover, the choke includes: a first common-mode choke and a first differential-mode choke, wherein: the first common-mode choke and the first differential-mode choke are electrically coupled in series via a first group of coil ends of the first common-mode choke and a first group of coil ends of the first differential-mode choke, and a second group of coil ends of one of the first common-mode choke and the first differential-mode choke are electrically coupled to the first terminal of the choke, and a second group of coil ends of the other are respectively electrically coupled to the second terminal and the at least one third terminal of the choke. The first common-mode choke can help provide high inductance to the high-frequency components of the common-mode current, which flows from the AC power source, since the impedance of the common-mode choke and the differential-mode choke depends on frequency on the same scale as inductance. The advantages of using the common-mode choke is that it provides twice the inductance of separate inductor design due to the coupling effect. Therefore it filters the common-mode current more effectively or the inductance size can be reduced for a given current ripple requirement.
Abstract:
A transformer-less static synchronous series compensator (SSSC) for an AC electrical power transmission system having a transmission line carrying an AC current and a method for protection against electrical damage are provided. The transformer-less SSSC including: a voltage source converter (100) having a DC input and an AC output and being configured to generate an alternating voltage with controllable magnitude and controllable phase angle across the AC output, the AC output being configured to inject the generated alternating voltage into a phase of the transmission line; a filter circuit (101) being arranged coupled with the voltage source converter (100) in parallel across the AC output of the voltage source converter (100); a bypass circuit (102); and an electrical current limiting circuit (103) being coupled with the bypass circuit (102) in series; wherein: the series-coupled current bypass circuit (102) and electrical current limiting circuit (103) are coupled with a first capacitive element (1011) of the filter circuit (101) in parallel. The transient nature of the electrical current limiting circuit (103) will limit the increase in the current flowing through the thyristor of the bypass circuit (102) thus limit the current peak when the bypass circuit (102) is switched on. Consequently, the current limiting circuit (103) acts like limiting the current transients generated from the influences of both of the line fault current and the discharging current.
Abstract:
A hybrid charging system (12) for electric vehicles (14, 15) comprises an power converter (42) connectable to an electric AC grid (18); a transformer (44) connected with the power converter (42) with a primary winding (60); a secondary side AC-to-DC converter (46) connected with a secondary winding (62) of the transformer (44) and for providing a DC current for power transfer to an electric vehicle (15) via a cable (40); and a first inductive coil (24) connected in series with the primary winding (60) of the transformer (44) and for inductively coupling to a second inductive coil (28) for power transfer to an electric vehicle (14) via an air gap.
Abstract:
Embodiments of the present disclosure relates to a method and system for on-line condition monitoring of a direct current (DC) -link capacitor in a power converter. The method includes (a) detecting a first waveform of voltage at the DC-link capacitor generated when the power converter operates with an output voltage reference for a plurality of switching periods. The method also includes (b) determining, based on an estimated parameter related to condition monitoring of the DC-link capacitor, an estimated second waveform of voltage at the DC-link capacitor for at least one of the plurality of switching periods; and (c) determining a differential waveform between the first and second waveforms with respect to the at least one switching period of the step (b). In parallel to the step (a), the steps (b) and (c) are repeated by adjusting the estimated parameter step by step until the differential waveform approaches below a predetermined threshold. The method also includes (d) determining, based on the estimated parameter, a target parameter related to the condition monitoring of the DC-link capacitor.
Abstract:
It provides an AC-DC power converter and method for operating the same. The AC-DC power converter includes: an AC-DC conversion circuit with first controllable power switches, being configured to receive a first AC power and output a first DC power generated from the first AC power; a plurality of DC-DC conversion circuits each with intermediate conversion into a second AC power, being configured to receive the first DC power and output in combination a second DC power, wherein each of the plurality of DC-DC conversion circuits includes a full-bridge DC-AC conversion circuit with second controllable power switches having its DC side coupled across output of the AC-DC conversion circuit and an capacitive element inserted between two ends of its AC side; and a controller, being configured to: generate first control signal for turning on and off the first controllable power switches of the AC-DC conversion circuit such that DC voltage of the first DC power can be regulated within a DC voltage range; and generate a plurality of second control signals each for turning on and off the second controllable power switches of the corresponding full-bridge DC-AC conversion circuit of the plurality of DC-DC conversion circuits in full-bridge mode and half-bridge modes such that the plurality of DC-DC conversion circuits exhibit a multiple of steps of voltage gain; wherein: the DC voltage range of the AC-DC conversion circuit is set to cover voltage increase from two successive steps of the voltage gain.