The mixed active electric power filter circuit
Technical field
The utility model relates to active electric harmonic filter.
Background technology
Along with the development of power electronic product, the application of various power electronic equipments in electric power system, industry, traffic is increasingly extensive, and the harm that mains by harmonics caused also is on the rise.At present harmonic filter mainly contains two kinds of passive filter and active filters.Wherein:
The passive filter circuit is made up of inductance, capacitances in series, though simple in structure, filtering characteristic is subjected to influence on system parameters bigger, does not reach the effect of effective inhibition harmonic wave.
Active filter circuit mainly is made up of tri-level inversion circuit and two diode clamp circuits that form in parallel that four power device IGBT (or IGCT) series connection forms.Though it can improve power grid quality, reduce the power network current harmonic wave, sort circuit need increase the first-harmonic resonance branch road, to reduce the power system capacity of active filter.
Summary of the invention
The utility model provides a kind of novel mixed active electric power filter circuit in order to solve the shortcoming that above active power filtering and passive filtering exist.
For achieving the above object, the utility model circuit structure is: it comprises passive filter circuit and active filter circuit, it is characterized in that, passive filter circuit and active filter circuit adopt the mode that is connected in series, be active filter circuit as first order filtering, its output is connected on the output of active filter circuit.
During use, adopt above-mentioned three groups of identical circuit of structure to be connected on the every phase line of three phase network.
The utility model has the advantages that: this use is novel to be combined into one existing active filter circuit and passive filter circuit, improve power grid quality, reduce the power network current harmonic wave, reduce the active filter power system capacity, both simplify the structure of active filter circuit, overcome the defective of passive filter circuit again.For active power filter circuit, inverter circuit does not bear fundamental voltage, and inverter is output harmonic wave voltage, harmonic current only, so power system capacity can reduce, circuit structure is simpler than the circuit structure of common active filter, does not need the first-harmonic resonance branch road.
2, the utility model can be selected suitable inductance, capacitance parameter according to the harmonic wave situation at scene, makes resonance point near near the main harmonic frequency, can further reduce the power system capacity of Active Power Filter-APF like this.
3, the utility model filter circuit adopts the identical three-phase circuit form of structure, when the fooled modulation signal of control is zero, two power devices in the centre of active filter circuit are conductings, can provide path to line voltage like this, make Active Power Filter-APF not bear fundamental voltage.Inverter output inserts electrical network again with after the inductance of passive filter circuit, the capacitances in series, and fundamental voltage is mainly born by the electric capacity of passive filter circuit.
Description of drawings
Fig. 1 is the utility model embodiment circuit structure diagram.Be example with three groups of shared capacitor filters of active filter circuit among the figure.
Among the figure: 1 represents the branch road of capacitor filtering; 2,3,4 represent passive filter circuit, 5,6,7-represents active filter circuit.
C1, C2, C3, C4, C5 represent electric capacity, and L1, L2, L3 represent inductance, and D1, D2, D3, D4, D5, D6 represent clamp diode, and S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12 represent power device IGBT or IGCT.
Embodiment
Below in conjunction with accompanying drawing 1 and embodiment the utility model is made specific description.
As shown in Figure 1, the utility model is to be parallel with three groups of identical in structure circuit on three phase network, every phase line connects one group, from left to right be called first group, second group and the 3rd group successively, as can be seen from the figure, passive filter circuit 2 and active filter circuit 5 series connection form first group, passive filter circuit 3 and active filter circuit 6 series connection form second group, passive filter circuit 4 and active filter circuit 7 series connection form the 3rd group, in addition, on the DC power supply of active filter circuit, be parallel with the capacitor filter 1 of capacitor C 4, C5 composition.Wherein:
Passive filter circuit 2 in first group is in series by capacitor C 1 and inductance L 1, active filter circuit 5 is in series by power device S1, S2, S3 and S4, middle two power device S2, S3 and clamp diode D1, D2 parallel connection, passive filter circuit 2 is terminated at one of three phase mains with active filter circuit 5 series connection backs one and goes up mutually, the other end is connected between the power device S2 emitter and power device S3 collector electrode in the active filter circuit 5, and clamp diode D1, D2 serial connection mid point is connected in series mid point with capacitor C 4, C5 and is connected.
Passive filter circuit 3 in second group is in series by capacitor C 2 and inductance L 2, active filter circuit 6 is in series by four power device S5, S6, S7 and S8, middle two power device S6, S7 and clamp diode D3, D4 parallel connection, passive filter circuit 3 is terminated at one of three phase mains with active filter circuit 6 series connection backs one and goes up mutually, the other end is connected in the active filter circuit 6 between the power device S6 emitter and power device S7 collector electrode, and clamp diode D3, D4 serial connection mid point is connected in series mid point with capacitor C 4, C5 and is connected.
Passive filter circuit 4 in the 3rd group is in series by capacitor C 3 and inductance L 3, active filter circuit 6 is in series by four power device S9, S10, S11 and S12, middle two power device S10, S11 and two diode D5, D6 parallel connection, passive filter circuit 4 is terminated at one of three phase mains with active filter circuit 7 series connection backs one and goes up mutually, the other end is connected in the active filter circuit 7 between the power device S10 emitter and power device S11 collector electrode, and clamp diode D5, D6 serial connection mid point is connected in series mid point with capacitor C 4, C5 and is connected.