A kind of three electric capacity mid point clamper type phase three-wire three circuit of power factor correction
Technical field
The utility model relates to a kind of phase three-wire three circuit of power factor correction, especially relates to a kind of three electric capacity mid point clamper type phase three-wire three circuit of power factor correction.
Background technology
Power factor correction in recent years (PFC) circuit has obtained very big development, and the single-phase power factor correcting technology reaches its maturity, and three-phase power factor correcting circuit has seriously limited its application because of its control is complicated.
Present widely used three-phase power factor correcting circuit as shown in Figure 1, it comprises inductance L 1-L3, three-phase commutation bridge D1-D6, capacitor C 4-C5 and switch S 1-S3; A road of the input of three-phase commutation bridge D1-D6 connects through inductance L 1-L3 respectively and exchanges input R phase, S phase, T phase, connects the output of three-phase commutation bridge D1-D6 after the capacitor C 4-C5 series connection; Capacitor C 4 equates that with the appearance value of C5 its mid point O connects control ground through switch S 1-S3 respectively for control ground, another road of the input of three-phase commutation bridge D1-D6.During circuit working, make switch S 1-S3 conducting, and make input current follow input ac voltage, thereby realize power factor correction by the ON time of control switch S1-S3 by control.Because the ON time of control switch S1-S3 need use the node of equivalent capacitance C4, C5 as control ground, but the node voltage of capacitor C 4, C5 is all being followed input ac voltage do interchange variation all the time during circuit working, and this control is to use simulation control to realize.Present way is to use Digital Signal Processing (DSP) that control signal is divided into hundreds of kind situation, forces to make the ON time balance of switch S 1-S3 realize power factor correction, just the space vector control technology.But space vector control is very complicated, makes the development of three-phase activity coefficient adjustment technology be subjected to serious restriction, especially can't realize by the strategy of analog circuit control.
The utility model content
The technical problems to be solved in the utility model provides a kind of analog circuit that can use and controls, three simple in structure, practical electric capacity mid point clamper type phase three-wire three circuit of power factor correction.
For solving the problems of the technologies described above, technical solution adopted in the utility model is: a kind of three electric capacity mid point clamper type phase three-wire three circuit of power factor correction, and it comprises inductance L 1-L3, three-phase commutation bridge D1-D6, capacitor C 4-C5 and switch S 1-S3; A road of the input of described three-phase commutation bridge D1-D6 connects through inductance L 1-L3 respectively and exchanges input R phase, S phase, T phase, connects the output of three-phase commutation bridge D1-D6 after the described capacitor C 4-C5 series connection, and described capacitor C 4 is control ground with the node O of C5; Another road of the input of described three-phase commutation bridge D1-D6 meets node O through switch S 1-S3 respectively; It is characterized in that it also comprises three capacitor C 1-C3, the end of described three capacitor C 1-C3 connects respectively and exchanges input R phase, S phase, T phase, its another termination control ground; The appearance value of described three capacitor C 1-C3 equates.
Adopt the beneficial effect that technique scheme produced to be: the utility model when realizing three-phase electricity input current-sharing, has suppressed the runaway electric circuit that causes because influence each other between the three-phase by the equilibrium control to the equal polarity free capacitor of three appearance values; Compared with prior art, the utility model is simple in structure, practical, can use existing ripe analog circuit that correcting circuit is controlled, and does not need to carry out the function that complicated space vector control just can realize power factor correction.
Description of drawings
Fig. 1 is traditional three-phase power factor correcting circuit;
Fig. 2 is a circuit diagram of the present utility model.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
As shown in Figure 2, a kind of three electric capacity mid point clamper type phase three-wire three circuit of power factor correction, it comprises inductance L 1-L3, three-phase commutation bridge D1-D6, capacitor C 4-C5 and switch S 1-S3; A road of the input of described three-phase commutation bridge D1-D6 connects through inductance L 1-L3 respectively and exchanges input R phase, S phase, T phase, connects the output of three-phase commutation bridge D1-D6 after the described capacitor C 4-C5 series connection, and described capacitor C 4 equates that with the appearance value of C5 its node O is control ground; Another road of the input of described three-phase commutation bridge D1-D6 meets node O through switch S 1-S3 respectively; It is characterized in that it also comprises three capacitor C 1-C3, the end of described three capacitor C 1-C3 connects respectively and exchanges input R phase, S phase, T phase, its another termination control ground; The appearance value of described three capacitor C 1-C3 equates.
The utility model has increased by three capacitor C 1-C3 that the appearance value equates at ac input end on the basis of traditional phase three-wire three circuit of power factor correction.During circuit working, make the R phase by the sharing control between the three-phase, the S phase, electric current between the T phase reaches balance, because the mid-point voltage average out to zero of three-phase alternating current, pass through C1, C2, the effect of C3, the voltage that this circuit is kept at least one ac cycle on control ground (mid point) O is approximately zero, guaranteed that voltage clamp on control ground (mid point) O is near zero, thereby obtained in fact also non-existent zero line, and the circuit of three-phase activity coefficient adjustment has been obtained huge simplification, also just make the power factor of phase three-wire three can use the independent control of three-phase to realize, overcome traditional correcting circuit and must use complicated space vector control could realize the shortcoming of power factor correction, made correcting circuit can use existing ripe analog circuit to control.