Power factor correcting circuit of part of active power supplies

Abstract

The invention relates to a power supply technique, in particular to a power factor correcting circuit of part of active power supplies, which comprises a full-wave rectification power supply, whereinthe anode of the full-wave rectification power supply is connected with the anode of a diode through an inductor; the cathode of the diode is connected with the anode of a load; a current detecting unit is connected between the cathode of the load and the cathode of the full-wave rectification power supply in series; the load is connected with a capacitor in parallel; a controlled switch and a voltage detecting unit are connected in parallel between the anode of the diode and the cathode of the load; the current in the load is larger than a critical current which has a first critical voltage value correspondingly; and when the input voltage of the full-wave rectification power supply is higher than a second critical voltage value and is lower than a third critical voltage value, the controlled switch is controlled to be opened, and on the contrary, the controlled switch is controlled to be closed. The power factor correcting circuit can further improve the circuit power factor and further reduce the switching frequency of the controlled switch under the condition of generating less electromagnetic interference.

Description

technical field [0001] The invention relates to power supply technology, in particular to a partial active power supply power factor correction circuit. Background technique [0002] In the power grid, various loads, especially non-linear loads, have a major impact on the quality of power grid power supply. For example, the power supply of many electrical appliances needs to convert the alternating current of the grid into direct current, and the pulsating current generated during the rectification process contains a large number of current harmonic components. These current harmonic components flow back into the grid, which will cause harmonic "pollution" to the grid. When the current flows through the line impedance, it will cause a harmonic voltage drop and distort the sine wave grid voltage. In addition, the generated harmonics also cause the power factor of the grid current to decrease, increase the loss of the distribution system conductors and transformers; and incre...

AI Technical Summary

Problems solved by technology

The problem of this kind of power factor correction circuit is: the switching frequency of the internal switching tube is very high (generally above 20K), so it will generate considerable electromagnetic interference during operation, which will make the interference voltage and interference power of the system exceed the standard. In order to suppress the PFC The interference brought by itself generally requires multi-stage filtering, which will inevitably increase the cost of the frequency conversion control system

[0019] However, in terms of power factor improvement, this PFC method does not achieve the nearly 100% power factor effect of full-range active PFC, and the switching frequency of the controlled switch will still be high, so its improvement is not satisfactory

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