CN206422703U - A kind of single-phase AC DC converters corrected based on high power factor - Google Patents

Abstract

The utility model relates to a single-phase AC-DC converter based on high power factor correction. The active PFC circuit connected to the filter circuit, the switch conversion circuit composed of a power switch tube and the resistor RSENSE connected to the active PFC circuit, and the output rectifier circuit composed of the output rectifier circuit DBOOST and the output filter circuit CBULK of the switch conversion circuit filter circuit and DC output terminal VOUT; the active PFC circuit includes a PFC control chip, a current sampling circuit and a voltage sampling circuit connected to the PFC control chip, and the PFC control chip obtains voltage and current signals according to the current sampling circuit and the voltage sampling circuit phase compensation for the phase difference.

Description

A Single-phase AC-DC Converter Based on High Power Factor Correction

technical field

The utility model relates to the field of alternating current and direct current conversion, in particular to a single-phase AC-DC converter based on high power factor correction.

Background technique

Power factor correction is referred to as PFC, which is generally used in switching power supply equipment with nonlinear load terminals. Since most of the loads in this type of switching power supply are nonlinear loads, that is, there are a large number of nonlinear devices inside the load, these nonlinear devices will cause input There is a phase difference between the AC voltage signal and the AC current signal, resulting in a very low energy utilization rate, such as the switching power supply of the most commonly used fluorescent lamp equipment in daily life, and the switching power supply in various military and civilian electronic equipment. All should add a power factor correction circuit to the front end of its switching power supply to improve the utilization rate of electric energy. There is no power supply with PFC circuit. Generally, the input terminal of such a power supply uses a diode rectifier capacitor filter. This circuit has a disadvantage that it can only use the energy near the peak and trough of the AC. There is input current near the peak and trough. Other time periods There is no input current, and such a power supply has very low energy efficiency.

Regarding the power factor correction of the power supply, the most widely used technology on the market is passive PFC. Passive PFC generally uses the inductance/capacitance compensation method to reduce the phase difference between the input AC fundamental wave current and voltage to improve the power factor. This power factor The correction method can only reach 0.7~0.8, which is generally near the high-voltage filter capacitor/inductance, and there is a premise that the load characteristics must be estimated in advance. The passive PFC circuit corresponding to the inductive and capacitive load terminals is very different. From this point It can be seen that the application compatibility of passive PFC is very poor, requires high professional knowledge of users, and usually requires series or parallel connection of many inductors and capacitors, which directly leads to large volume, heavy weight, low energy conversion efficiency, and easy to generate power frequency vibration and noise issues.

Utility model content

The purpose of this utility model is to provide a single-phase AC-DC converter based on high power factor correction for the technical problem of low power factor obtained by the existing power factor correction method of switching power supply, which can provide higher Power factor, high conversion efficiency of power supply.

The technical scheme that the utility model adopts is as follows:

A single-phase AC-DC converter based on high power factor correction, including an AC input terminal AC, an input rectifying and filtering circuit composed of a rectifier bridge and an input filtering circuit Cin connected to the AC input terminal, and an input rectifying and filtering circuit connected to the input rectifying and filtering circuit An active PFC circuit, a switch conversion circuit composed of a power switch tube and a resistor RSENSE connected to the active PFC circuit, and an output rectification filter circuit composed of an output rectifier circuit DBOOST and an output filter circuit CBULK of the switch conversion circuit, and a DC Output terminal VOUT; the active PFC circuit includes a PFC control chip, a current sampling circuit connected to the PFC control chip, a voltage sampling circuit, and the PFC control chip obtains voltage and current signals according to the phase difference of the current sampling circuit and the voltage sampling circuit. phase compensation. The PFC control chip and the peripheral current sampling circuit and voltage sampling circuit actively obtain the phase difference of the current and voltage signals, internally compensate the phase difference of the current or voltage signal to make the phase difference close to 0, and then adjust the output pulse to drive the switch to change The power switching tube in the circuit performs switching action to realize power conversion.

In the above scheme, the model of the PFC control chip is NCP1606, the current sampling circuit includes an LBOOST transformer, and the voltage sampling circuit includes feedback voltage dividing resistors ROUT1 and ROUT2 in series; the secondary side of the LBOOST transformer in the current sampling circuit passes through the limiter The current resistance RZCD is connected to the ZCD pin of the NCP1606 chip to obtain the input AC current signal. The feedback voltage divider resistors ROUT1 and ROUT2 connected in series in the voltage sampling circuit are connected in parallel to the DC output terminal. The connection between the feedback voltage divider resistor ROUT1 and ROUT2 The point is connected to the FB pin of the NCP1606 chip to obtain the voltage signal through feedback; the NCP1606 chip compensates according to the phase difference of the obtained voltage and current signals, and then controls the DRV pin to output pulses to drive the power switch tube in the switching conversion circuit to perform switching actions.

In the above solution, an EMI electromagnetic interference filter is also provided between the AC input terminal and the input rectification filter circuit.

In summary, due to the adoption of the above-mentioned technical solution, the beneficial effects of the utility model are:

The utility model actively obtains the current and voltage signal phase difference by adding a PFC control chip and peripheral current sampling circuit and voltage sampling circuit, and internally performs phase compensation on the current or voltage signal to make the phase difference close to 0, and then The output pulse is adjusted to drive the power switching tube in the switching conversion circuit to perform switching action to realize power conversion. Compared with the traditional power factor correction method, this design is a closed-loop adjustment, the phase difference can approach 0 infinitely, and the power factor is as high as 0.9. Moreover, compared with the traditional power factor correction method, this design avoids the volume and weight problems caused by the introduction of a large number of capacitors and inductances. At the same time, the design has high compatibility and does not need to consider the inductive or capacitive load. Compensation, not easy to produce power frequency vibration and noise, etc., has good social significance and market prospects.

Description of drawings

Fig. 1 is a schematic circuit diagram of the utility model;

Fig. 2 is a schematic diagram of a distorted AC voltage and current signal;

Fig. 3 is a schematic diagram of AC voltage and current signals after power factor correction of the utility model.

detailed description

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

As shown in the figure, a single-phase AC-DC converter based on high power factor correction includes an AC input terminal AC, an input rectifier and filter circuit composed of a rectifier bridge and an input filter circuit Cin connected to the AC input terminal, and an input rectifier and filter circuit connected to the AC input terminal. The active PFC circuit connected to the rectification filter circuit, the switch conversion circuit composed of a power switch tube and the resistor RSENSE connected to the active PFC circuit, and the output of the switch conversion circuit composed of an output rectifier circuit DBOOST and an output filter circuit CBULK Rectifier filter circuit and DC output terminal VOUT; the active PFC circuit includes a PFC control chip, a current sampling circuit and a voltage sampling circuit connected to the PFC control chip, and the PFC control chip obtains voltage and current according to the current sampling circuit and the voltage sampling circuit The phase difference of the signal is compensated. The PFC control chip and the peripheral current sampling circuit and voltage sampling circuit actively obtain the phase difference of the current and voltage signals, internally compensate the phase difference of the current or voltage signal to make the phase difference close to 0, and then adjust the output pulse to drive the switch to change The power switching tube in the circuit performs switching action to realize power conversion.

Preferably, the model of the PFC control chip is NCP1606, the current sampling circuit includes an LBOOST transformer, and the voltage sampling circuit includes feedback divider resistors ROUT1 and ROUT2 in series; the secondary side of the LBOOST transformer in the current sampling circuit is limited by current The resistor RZCD is connected to the ZCD pin of the NCP1606 chip to obtain the input AC current signal. The feedback divider resistors ROUT1 and ROUT2 connected in series in the voltage sampling circuit are connected in parallel to the DC output terminal. The connection point of the feedback divider resistor ROUT1 and ROUT2 Connect to the FB pin of the NCP1606 chip to obtain the voltage signal through feedback; the NCP1606 chip compensates according to the phase difference of the obtained voltage and current signals, and then controls the DRV pin to output pulses to drive the power switch in the switching conversion circuit to switch.

Preferably, an EMI electromagnetic interference filter is also provided between the AC input terminal and the input rectification filter circuit.

The above are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model should be included in the utility model. within the scope of protection.

Claims (3)

1. a kind of Single-phase AC-DC converters corrected based on high power factor, it is characterised in that including ac input end AC, with Ac input end connection by rectifier bridge, input filter circuit C_inThe input rectifying filter circuit of composition, is filtered with input rectifying Circuit connection active pfc circuit, be connected with the active pfc circuit by power switch pipe and resistance R_SENSEConstitute Switch transformed circuit, with switch transformed circuit by output rectification circuit D_BOOST, output filter circuit C_BULKThe output of composition is whole Flow filter circuit and DC output end V_OUT；The active pfc circuit includes PFC control chips, connects with PFC control chips Current sampling circuit, the voltage sample circuit connect, PFC control chips are obtained according to current sampling circuit, voltage sample circuit Voltage, the phase difference of current signal carry out phase compensation.

2. a kind of Single-phase AC-DC converters corrected based on high power factor as claimed in claim 1, it is characterised in that institute PFC control chip model NCP1606 are stated, the current sampling circuit includes LBOOST transformers, the voltage sample circuit Feedback divider resistance R comprising series connection_OUT1、R_OUT2；LBOOST transformers time side passes through current-limiting resistance in the current sampling circuit R_ZCDIt is connected to the ZCD pins of NCP1606 chips and is connected with obtaining in the ac current signal of input, the voltage sample circuit Feedback divider resistance R_OUT1、R_OUT2It is connected in DC output end, feedback divider resistance R in parallel_OUT1With R_OUT2Tie point connection To the FB pins of NCP1606 chips to feed back acquirement voltage signal；NCP1606 chips are according to the voltage of acquisition, current signal Phase difference is compensated, and then controls the power switch pipe in DRV pins output pulse driven switch translation circuit to be switched Action.

3. a kind of Single-phase AC-DC converters corrected based on high power factor as claimed in claim 1, it is characterised in that EMI EMI FILTERs are additionally provided between ac input end and input rectifying filter circuit.