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AssigneeHitachi, Ltd.
InventorsHikaru Meguro, Hiroshi Ikarashi, Keizo Shimada, Masashi Toyota
Estimating the term…
By reduction in loss and noise of a three-phase reactor on the AC side of an electric power converter, compactness and reduction in weight of the reactor are realized, and countermeasures for heat and noise are reduced, and a specific frequency component is reduced, thus cost reduction and conversion efficiency are improved, and carriers of a controller are prepared in correspondence to the phases of the electric power converter, and moreover a phase difference of each carrier is set properly.
An electric power converter for switching a plurality of switching devices connected between an AC line and a DC line operated by respective high frequency pulses outputted from a controller so as to be switched synchronously with the respective pulses and converting electric power from a DC circuit to a multi-phase AC circuit or from said multi-phase AC circuit to said DC circuit, the switching devices being provided corresponding to the phases, wherein a reactor is inserted into each phase of said AC line such that a load system side of each reactor is operatively connected with a terminal of an associated capacitor being connected to a line between the AC circuit and DC circuit so as to form a high frequency filter for absorbing generated high frequency waves, the line connecting the AC circuit and DC circuit so as to bypass the switching devices, and said controller compares output of a plurality of carrier sources with output of a signal wave source and supplies high frequency pulses which are output of said comparison to said switching device, and phases of said plurality of carrier sources have predetermined phase differences so as to reduce a synthetic harmonic current of the line between the AC circuit and DC circuit, wherein each of said plurality of carrier sources comprises a triangular waveform.
An electric power converter comprising a main electric power conversion circuit bridge-connecting a plurality of switching devices, a control circuit for switching said switching device operated by respective high frequency pulses outputted from a controller so as to be switched synchronously with the respective pulses and converting electric power between a direct current and an alternating current, the switching devices being provided corresponding to the phases, and a high frequency filter formed by inserting a reactor into each phase of an AC line connected to said main electric power conversion circuit and by connecting a side of said reactor that is on an opposite side of said main electric power conversion circuit to a terminal of an associated capacitor and another terminal of each associated capacitor to a line between AC and DC sides of the main electric power conversion circuit for absorbing generated high frequency waves, the line connecting the AC circuit and DC circuit so as to bypass the switching devices, wherein said controller compares output of a plurality of carrier sources with output of a signal wave source and supplies high frequency pulses which are output of said comparator to said switching device, and phases of said plurality of carriers have predetermined phase differences so as to reduce a synthetic harmonic current of the line between the AC circuit and DC circuit, wherein each of said plurality of carrier sources comprises a triangular waveform.
An electric power converter for switching a plurality of switching devices connected between an AC line and a DC line operated by respective high frequency pulses outputted from a controller so as to be switched synchronously with the respective pulses, thereby converting electric power from a direct current to an alternating current or from said alternating current to said direct current, wherein a high frequency filter is provided and comprised of a reactor arranged in each phase of said AC line so that a side of each reactor is operatively connected to a terminal of an associated capacitor with another terminal of each associated capacitor operatively connected to a line between AC and DC sides for absorbing generated high frequency waves generated, the line connecting the AC circuit and DC circuit so as to bypass the switching devices, the switching devices being provided corresponding to the phases, and said controller adjusts optimally phase differences of a plurality of carrier sources, compares output of a signal wave source, and supplies high frequency pulses which are output of said comparator to said switching device so as to reduce a synthetic harmonic current of the line between the AC circuit and DC circuit, wherein each of said plurality of carrier sources comprises a triangular waveform.
A method for switching between an AC line and a DC line by respective high frequency pulses converting power between an AC circuit and a DC circuit, comprising:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
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Details of apparatus for conversion: arrangements for reducing harmonics from AC input or output
Using semiconductor devices only: in a bridge configuration
With automatic control of output waveform or frequency: by pulse width modulation
With automatic control of output voltage or current: with analogue control of three-phase output
Term ended 30 Mar 2025 (estimated)
The present invention relates to an electric power converter.
In the electric power converter, for example, as shown in FIG. 1 of Japanese Patent Laid-open No. Hei 3 (1991)-218270, to remove high-frequency components generated in an AC line and a DC line, a capacitor is connected between the AC line and the DC line. The converter compares signal waves of respective phases having a phase difference from one carrier common to the respective phases, gives positive logic and negative logic high frequency pulses, which are output of comparators, to switching devices to control the PWM.
When a function for removing the high-frequency components generated in the AC line and DC line is provided, the following advantages can be obtained.
FIG. 1 is a schematic view of a three-phase three-wire inverter circuit,
FIG. 2 is a drawing showing the phase relationship of the signal wave and carrier in the circuit shown in FIG. 1,
FIG. 3 is a schematic view of a three-phase four-wire inverter circuit when two DC power sources are used, and
FIG. 1 is a circuit diagram showing the electric power converter of an embodiment of the present invention, which is composed of a main circuit 12, a load system 6, and PMW controller 13. The main circuit 12 is structured so as to connect 6 switching devices T1, T2, T3, T4, T5, and T6 and diodes D1, D2, D3, D4, D5, and D6 connected respectively to the switching devices T1 to T6 in parallel as a three-phase bridge. To the DC side of the three-phase bridge circuit, DC power supplies 9A and 9B connected in series are connected.
The switching devices T1 to T6 of the main circuit 12 are driven by an on-off control signal for PWM (pulse width modulation) control given from the PWM controller 13 and function as a voltage source PWM converter.
The AC side of the main circuit 12 is connected to the load system 6 via the AC lines. The DC side of the main circuit 12 is connected to the AC side via the line N. Into the phases of the AC lines, reactors 4 are respectively inserted and between the AC lines of the reactors 4 on the load system side and the line N, capacitors 5u, 5v, and 5w are connected. In this embodiment, the line N is connected to the middle point of the DC power supplies 9A and 9B.