TW201807944A - AC-DC power converter - Google Patents

Abstract

The present invention relates to an AC-DC power converter, including a pre-stage AC-DC power converting unit and a post-stage AC-DC power converting unit electrically connected to the pre-stage AC-DC power converting unit. The pre-stage AC-DC power converting unit serves to correct power factor and to lower voltage, and the post-stage AC-DC power converting unit serves to achieve a higher step-down ratio.

Description

AC-DC power converter

The invention relates to an AC-DC power converter, especially a power factor correction provided by a first-half stage AC-DC power conversion unit, and electrically connecting a second-stage DC of one of the first half-stage AC-DC power conversion units through electrical -AC-DC power converter with high step-down ratio.

According to the application of AC-DC power converters, such as various DC voltage input electronic products, such as mobile phone charging, lighting drive circuits, audio, computers, etc.

At present, the previous cases of AC-DC power converters are the Republic of China Invention Patent Bulletin No. I528702 (an AC-DC converter with a high power factor and a high step-down ratio), which includes a filter circuit, a rectifier, a The coupled inductor includes a primary winding and a secondary winding, two sets of switching switches, three diodes, an inductor, a capacitor, and an output capacitor, which are connected into a front-stage AC-DC power conversion unit and electrical properties. One of the first half-stage AC-DC power conversion units is connected to the second half-stage DC-DC power conversion unit. The first half-stage AC-DC power conversion unit of the previous case provides a power factor correction to improve the power utilization rate, and the second half-stage DC-DC power conversion unit of the previous case provides the effect of a high step-down ratio.

However, the above-mentioned pre-patent case uses two sets of changeover switches, the operation method is more complicated, and there is still room for improvement.

Therefore, in order to improve the above-mentioned shortcomings, the present inventors are committed to research and propose an AC-DC power converter of the present invention, including:

A front half-stage AC-DC power conversion unit. The front half-stage AC-DC power conversion unit includes an AC input voltage terminal, a filter circuit, a rectifier, a switch, a first diode, a first inductor, and a First capacitor, two ends of the AC input voltage terminal are electrically connected to the filter circuit, the filter circuit is electrically connected to the rectifier, and one end of the rectifier is electrically connected to one end of the first inductor and the first diode. The cathode end, the other end of the first inductor is electrically connected to the switch and one end of the first capacitor, and the other end of the first capacitor is electrically connected to the anode end of the first diode and the fourth diode. Cathode terminal; a rear half-stage DC-DC power conversion unit is electrically connected to the front half-stage AC-DC power conversion unit, and the rear half-stage DC-DC power conversion unit includes a second inductor, a third inductor, and a first inductor; A second diode, a third diode, a fourth diode, an output capacitor and a load, the cathode terminal of the fourth diode is electrically connected to the other end of the first capacitor, the One end of the three inductors is electrically connected to the anode end of the second diode and the anode end of the fourth diode, and the other end of the third inductor is electrically connected to the anode end of the third diode and the output capacitor. One end, the load end, the other end of the rectifier is electrically connected to the other end of the switch, the cathode end of the third diode, one end of the second inductor, and the other end of the second inductor is electrically connected to the second two. The cathode end of the pole body, the other end of the output capacitor, and the other end of the load; the first half-stage AC-DC power conversion unit is used for power factor correction and voltage reduction, and the conversion is achieved by the second half-stage DC-DC power conversion unit High buck ratio.

Further, the filter circuit is an LC filter.

Further, the rectifier is a full-wave bridge rectifier.

Further, the first half-stage AC-DC power conversion unit is operated in a discontinuous conduction mode.

Further, the second half stage DC-DC power conversion unit is operated in a discontinuous conduction mode.

Further, the second inductance and the third inductance have the same inductance.

Further, when the switch is turned on, the second inductor and the third inductor are connected in series to store energy.

Further, when the switch is turned off, the second inductor and the third inductor release energy in parallel.

According to the above technical features, the following effects can be achieved:

1. Use only one toggle switch for easy control.

2. It can reach almost unit power factor.

3. Has low input current total harmonic distortion.

4. Has a stable DC output voltage.

5. It can provide the function of high step-down ratio.

6. When the universal input voltage is 90 to 264V _rms , the DC link voltage is lower than the peak value of the input voltage and far less than 450V _DC , which can meet the practical principle.

In summary, the main effects of the AC-DC power converter of the present invention will be clearly shown in the following embodiments.

First refer to the first figure, which is a circuit diagram of the AC-DC power converter (1) of this embodiment, which includes a first-half stage AC-DC power conversion unit (11) and a second-half stage DC-DC power conversion unit (12). ),among them:

The first half-stage AC-DC power conversion unit (11) includes an AC input voltage terminal (111), a filter circuit (112), a rectifier (113), a switch (114), and a first diode (115). ), A first inductor (116) and a first capacitor (117). In this embodiment, the filter circuit (112) is an LC filter and includes a filter inductor (1121) and a filter capacitor (1122), and the rectifier (113) is a full-wave bridge rectifier. , And contains four general diodes (1131) with forward bias, the arrangement of which is a bridge type, the AC voltage input from the AC input voltage terminal (111) is rectified into a DC voltage, which is AC- DC conversion. Further, the first half-stage AC-DC power conversion unit (11) is operated in a discontinuous conduction mode. The two ends of the AC input voltage terminal (111) of the first half-stage AC-DC power conversion unit (11) are electrically connected to the filter circuit (112), and the filter circuit (112) is electrically connected to the rectifier (113). ), One end of the rectifier (113) is electrically connected to one end of the first inductor (116) and the cathode end of the first diode (115), and the other end of the first inductor (116) is electrically connected to the switch The switch (114) and one end of the first capacitor (117). The other end of the first capacitor (117) is electrically connected to the anode terminal of the first diode (115).

The rear half-stage DC-DC power conversion unit (12) is electrically connected to the front half-stage AC-DC power conversion unit (11). The second half stage DC-DC power conversion unit (12) includes a second inductor (121), a third inductor (122), a second diode (123), a third diode (124), a The fourth diode (125), an output capacitor (126), and a load (127). One end of the third inductor (122) is electrically connected to the anode terminal of the second diode (123) and the anode terminal of the fourth diode (125). The other end of the third inductor (122) is electrically connected. Connected to the anode terminal of the third diode (124), the output capacitor (126) and the load (127), the other end of the rectifier (113) is electrically connected to the other end of the switch (114), the The cathode terminal of the third diode (124), one end of the second inductor (121), and the other end of the second inductor (121) are electrically connected to the cathode terminal of the second diode (123), and the output capacitor. (126) the other end and the load (127) the other end. Wherein, in this embodiment, the second inductance (121) and the third inductance (122) of the second half stage DC-DC power conversion unit (12) have the same inductance, and the second half stage DC-DC power supply Conversion unit (12) operates in discontinuous conduction mode

It should be further explained that this embodiment adopts single-stage control and uses pulse width modulation technology to drive the switch (114) on or off in the circuit.

Before operation, please refer to the second figure. The second figure is the main waveform when the input voltage at the AC input voltage terminal (111) is a positive half wave. Because the positive and negative half waves of the AC input voltage are symmetrical, So the following operation is analyzed in the interval [0, π / ω], where ω is the angular frequency.

During operation, please refer to the second to sixth figures, wherein the third to sixth figures are equivalent circuit diagrams of the first figure, that is, the AC voltage e _{in is} input from the AC input voltage terminal (111) to the The filter circuit (112) is input to the rectifier (113) with a V _S voltage, wherein before the input to the rectifier (113), it is AC power [the AC input voltage terminal (111), the AC voltage e _in and the filtering The circuit (112) is shown in the first figure for cooperation. In this embodiment, when the input voltage at the AC input voltage terminal is a positive half wave, it is mainly divided into four modes:

Mode 1: Please refer to the third figure and cooperate with the second figure. The operation interval is [kT _S , t _k1 ]. When the switch (114) is in the on state, its current path is as the arrow in the third figure. Pointing as shown. At this time, the input power is used to store energy to the first inductor (116). The energy stored in the first capacitor (117) will be released to the second inductor (121), the third inductor (122), the output capacitor (126), and the load (127). In this operation interval, the second inductor (121) and the third inductor (122) are mainly used to store energy in series. This operation mode 1 ends at t = t _k1 , and at this time, the changeover switch (114) is turned off.

Mode 2: Please refer to the fourth diagram and cooperate with the second diagram. The operation interval is [t _k1 , t _k2 ]. When the switch-on relationship (114) is off, the current path is as indicated by the arrow in the fourth diagram. As shown. The energy stored in the first inductor (116) will be released to the first capacitor (117). At the same time, the second inductor (121) and the third inductor (122) are connected in parallel to release energy to the output capacitor (126) and the load (127). This operation mode 2 ends at t = t _k2 , at which time the energy stored in the first inductor (116) is released.

Mode 3: Please refer to the fifth figure and cooperate with the second figure. The operation interval is [t _k2 , t _k3 ]. At this time, the switch (114) is still in the off state, and its current path is as shown in the fifth figure. The arrows point as shown. The second inductor (121) and the third inductor (122) are connected in parallel, and continuously release energy to the output capacitor (126) and the load (127). This operation mode ends at t = t _k3 , at which time the energy stored in the second inductor (121) and the third inductor (122) is released.

Mode 4: Please refer to the sixth diagram and cooperate with the second diagram. The operation interval is [t _k3 , (k + 1) T _S ]. At this time, the switch (114) is still in the off state, and its current path is This is indicated by the arrow pointing in the sixth figure. At this time, only the output capacitor (126) releases energy to the load (127). This operation mode 4 ends at the beginning of the next switching cycle, at which time the switch (114) is turned on.

Further, as in the seventh see FIG, eighth and ninth shown in FIG described embodiment of the present embodiment operates in the input voltage of 90V _rms, the output voltage of 25V _DC, the input power of 100W output voltage e _in, the input current i _in, Analog waveforms of the first inductor current i _L1 , the second inductor current i _L2 , the third inductor current i _L3 , the DC link voltage V _c1, and the output voltage V _o . And FIG refer tenth, eleventh and twelfth shown in FIG described embodiment of the present embodiment operates in the input voltage of 264V _rms, the output voltage of 25V _DC, the input power of 100W output voltage e _in, the input current i _in, first An analog waveform of an inductor current i _L1 , a second inductor current i _L2 , a third inductor current i _L3 , a DC link voltage V _c1, and an output voltage V _o . Among them, in the seventh chart and the tenth chart, from the waveforms of the input voltage e _in and the input current i _in , it can be seen that the AC-DC power converter in this embodiment can achieve a near unit power factor and a low total input current. The effect of harmonic distortion. In the eighth and eleventh figures, the waveforms of the first inductor current i _L1 , the second inductor current i _L2, and the third inductor current i _L3 can be seen before the AC-DC power converter in this embodiment. The second half stage is operated in discontinuous conduction mode. In the ninth and twelfth figures, from the waveforms of the DC link voltage V _C1 and the output voltage V _o , it can be seen that the DC link voltage V _{C1 is} less than the maximum value of the input voltage, and is far less than 450V _DC . Practical principles. And the output voltage V _{o is} stable and can be controlled at 25V to achieve the function of high step-down ratio.

Based on the description of the above embodiments, the operation, use and effects of the present invention can be fully understood, but the above-mentioned embodiments are only preferred embodiments of the present invention, and the implementation of the present invention cannot be limited in this way. The scope, that is, the simple equivalent changes and modifications made according to the scope of the patent application and the description of the invention, are all within the scope of the present invention.

(1) ‧‧‧AC-DC power converter
(11) ‧‧‧First half stage AC-DC power conversion unit
(111) ‧‧‧AC input voltage terminal
(112) ‧‧‧Filter Circuit
(1121) ‧‧‧Filter Inductor
(1122) ‧‧‧Filter Capacitor
(113) ‧‧‧Rectifier
(1131) ‧‧‧General Diode
(114) ‧‧‧Switch
(115) ‧‧‧First Diode
(116) ‧‧‧First inductor
(117) ‧‧‧First capacitor
(12) ‧‧‧The second half stage DC-DC power conversion unit
(121) ‧‧‧Second Inductance
(122) ‧‧‧Third inductance
(123) ‧‧‧Second Diode
(124) ‧‧‧Third Diode
(125) ‧‧‧ Fourth Diode
(126) ‧‧‧Output capacitor
(127) ‧‧‧Load

[First diagram] is a circuit diagram of an AC-DC power converter according to an embodiment of the present invention.

[Second figure] The main waveform diagram of the AC-DC power converter in the interval [0, π / ω] according to the embodiment of the present invention.

[Third figure] The current path of operation mode 1 when the AC-DC power converter operates in the interval [0, π / ω ] according to the embodiment of the present invention.

[Fourth Figure] The current path of the operation mode 2 when the AC-DC power converter operates in the interval [0, π / ω ] according to the embodiment of the present invention.

[Fifth Figure] The current path of the operation mode 3 when the AC-DC power converter operates in the interval [0, π / ω ] according to the embodiment of the present invention.

[Sixth figure] is the current path of operation mode 4 when the AC-DC power converter operates in the interval [0, π / ω ] according to the embodiment of the present invention.

[Seventh figure] It is an analog waveform of the input voltage e _in and the input current i _in when the AC-DC power converter operates at an input voltage of 90V _rms , an output voltage of 25V _DC, and an output power of 100W, and its waveform diagram The scale value is: e _in : 100V / div, i _in : 5A / div, time: 10ms / div.

[Eighth Figure] The first-inductance current i _L1 , the second-inductance current i _L2, and the third when the AC-DC power converter operates at an input voltage of 90V _rms , an output voltage of 25V _DC, and an output power of 100W according to an embodiment of the present invention The analog waveform of the inductor current i _L3 , the scale value of the waveform diagram is: i _L1 , i _L2 , i _L3 : 2A / div, time: 10ms / div.

[The ninth figure] is an analog waveform of the DC link voltage V _c1 and the output voltage V _o when the AC-DC power converter operates at an input voltage of 90 V _rms , an output voltage of 25 V _DC, and an output power of 100 W. The scale value of the waveform chart is: V _c1 , V _o : 20V / div, time: 10ms / div.

[Tenth figure] It is an analog waveform of the input voltage e _in and the input current i _in when the AC-DC power converter operates at an input voltage of 264V _rms , an output voltage of 25V _DC, and an output power of 100W, and its waveform diagram The scale value is: e _in : 200V / div, i _in : 1A / div, time: 10ms / div.

[Eleventh figure] The first inductor current i _L1 , the second inductor current i _L2, and the first inductor current i _L1 when the input voltage is 264 V _rms , the output voltage is 25 V _DC, and the output power is 100 W according to the embodiment of the present invention. The analog waveform of the three inductor current i _L3 , the scale value of the waveform diagram is: i _L1 , i _L2 , i _L3 : 2A / div, time: 10ms / div.

[Twelfth figure] It is an analog waveform of the DC link voltage V _c1 and the output voltage V _o when the AC-DC power converter operates at an input voltage of 264V _rms , an output voltage of 25V _DC, and an output power of 100W. The scale value of the waveform chart is: V _c1 , V _o : 50V / div, time: 10ms / div.

(1) ‧‧‧AC-DC power converter

(11) ‧‧‧First half stage AC-DC power conversion unit

(111) ‧‧‧AC input voltage terminal

(112) ‧‧‧Filter Circuit

(1121) ‧‧‧Filter Inductor

(1122) ‧‧‧Filter Capacitor

(113) ‧‧‧Rectifier

(1131) ‧‧‧General Diode

(114) ‧‧‧Switch

(115) ‧‧‧First Diode

(116) ‧‧‧First inductor

(117) ‧‧‧First capacitor

(12) ‧‧‧The second half stage DC-DC power conversion unit

(121) ‧‧‧Second Inductance

(122) ‧‧‧Third inductance

(123) ‧‧‧Second Diode

(124) ‧‧‧Third Diode

(125) ‧‧‧ Fourth Diode

(126) ‧‧‧Output capacitor

(127) ‧‧‧Load

Claims (8)

An AC-DC power converter includes: a front half-stage AC-DC power conversion unit, the front half-stage AC-DC power conversion unit includes an AC input voltage terminal, a filter circuit, a rectifier, a switch, and a first A diode, a first inductor, and a first capacitor, the two ends of the AC input voltage terminal are electrically connected to the filter circuit, the filter circuit is electrically connected to the rectifier, and one end of the rectifier is electrically connected to the first One end of the inductor is connected to the cathode terminal of the first diode, and the other end of the first inductor is electrically connected to the switch and one end of the first capacitor, and the other end of the first capacitor is electrically connected to the first diode. Anode terminal of the body; a rear half-stage DC-DC power conversion unit is electrically connected to the front half-stage AC-DC power conversion unit, and the rear half-stage DC-DC power conversion unit includes a second inductor, a third inductor, a A second diode, a third diode, a fourth diode, an output capacitor, and a load; the cathode terminal of the fourth diode is electrically connected to the first capacitor; One end, one end of the third inductor is electrically connected to the anode end of the second diode, the anode end of the fourth diode, and the other end of the third inductor is electrically connected to the anode end of the third diode. One end of the output capacitor and one end of the load, the other end of the rectifier is electrically connected to the other end of the switch, the cathode end of the third diode, one end of the second inductor, and the other end of the second inductor is electrically connected. The cathode terminal of the second diode, the other end of the output capacitor, and the other end of the load; the first half-stage AC-DC power conversion unit is used for power factor correction and voltage reduction, and the second half-stage DC-DC power conversion The conversion of the unit reaches a high step-down ratio. The AC-DC power converter according to item 1 of the patent application scope, wherein the filter circuit is an LC filter. The AC-DC power converter according to item 1 of the scope of patent application, wherein the rectifier is a full-wave bridge rectifier. The AC-DC power converter according to item 1 of the scope of patent application, wherein the first half-stage AC-DC power conversion unit is operated in a discontinuous conduction mode. The AC-DC power converter according to item 1 of the scope of patent application, wherein the second half-stage DC-DC power conversion unit is operated in a discontinuous conduction mode. The AC-DC power converter according to item 1 of the scope of patent application, wherein the second inductor and the third inductor have the same inductance. According to the AC-DC power converter described in item 1 of the scope of patent application, when the switch is turned on, the second inductor and the third inductor are connected in series to store energy. The AC-DC power converter according to item 1 of the scope of the patent application, wherein when the switch is turned off, the second inductor and the third inductor are configured to release energy in parallel.