TWI594560B - AC-DC power converter - Google Patents

Description

AC-DC power converter

The invention relates to an AC-DC power converter, in particular to a power factor correction provided by a front half-stage AC-DC power conversion unit, and is electrically connected to one of the front half-stage AC-DC power conversion units. - DC-to-DC power converter with DC power conversion unit and high step-down ratio.

Press, the application of AC-DC power converter is such as various DC voltage input electronic products, such as mobile phone charging, lighting drive circuit, audio, computer and so on.

At present, the previous case of the AC-DC power converter is the Republic of China Invention Patent No. I528702 "AC-DC converter with high power factor and high step-down ratio", including a filter circuit, a rectifier, and 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, and is connected to a front half AC-DC power conversion unit and electrical Connect one of the first half of the AC-DC power conversion unit to the latter half of the DC-DC power conversion unit. The former half-stage AC-DC power conversion unit of the previous case provides a power factor correction to improve power utilization, and the latter half of the DC-DC power conversion unit provides the high step-down ratio.

However, the above patents use two sets of switchers, the operation mode is more complicated, and there is still room for improvement.

Accordingly, in order to improve the above-mentioned deficiencies, the inventors have made an effort to study and propose an AC-DC power converter of the present invention, comprising: A front-half-level 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-stage AC-DC power conversion unit. a first capacitor, the two ends of the AC input voltage end are respectively electrically connected to the filter circuit, and 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 a 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 and the fourth diode of the first diode a cathode-side; a second-half-level DC-DC power conversion unit electrically connected to the first-stage AC-DC power conversion unit, the second-half-level DC-DC power conversion unit includes a second inductor, a third inductor, and a first a second diode, a third diode, a fourth diode, an output capacitor, and a load, the cathode end of the fourth diode is electrically connected to the other end of the first capacitor, One end of the three inductors 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 and the output capacitor 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, and the second inductor end, and the other end of the second inductor is electrically connected to the second The cathode end of the polar 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 step-down, and the conversion of the second-half-level DC-DC power conversion unit is achieved. High step-down ratio.

Further, the filter circuit is an LC filter.

Further, the rectifier is a full wave bridge rectifier.

Further, the front half AC-DC power conversion unit operates in a discontinuous conduction mode.

Further, the latter half-level DC-DC power conversion unit operates in a discontinuous conduction mode.

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

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

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

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

1. Only one switch is used, and the control is simple.

2. Can reach nearly unit power factor.

3. Has low input current total harmonic distortion.

4. Has a stable DC output voltage.

5. Can provide high step-down ratio function.

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 is much smaller than 450V _DC , which is in line with practical principles.

(1)‧‧‧AC-DC power converter

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

(111)‧‧‧AC input voltage terminal

(112)‧‧‧Filter circuit

(1121)‧‧‧Filter inductor

(1122)‧‧‧Filter Capacitor

(113)‧‧‧Rectifier

(1131)‧‧‧General diodes

(114)‧‧‧Switch

(115) ‧‧‧First Diode

(116)‧‧‧First inductance

(117)‧‧‧First Capacitor

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

(121)‧‧‧second inductance

(122)‧‧‧ Third inductance

(123)‧‧‧Secondary diode

(124)‧‧‧ Third Dipole

(125)‧‧‧Fourth diode

(126)‧‧‧ Output capacitance

(127)‧‧‧ Load

[First FIG. 1] is a circuit diagram of an AC-DC power converter according to an embodiment of the present invention.

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

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

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

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

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

[Seventh] is an analog waveform of an input voltage e _in and an input current i _in when an AC-DC power converter of the embodiment of the present invention 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 values are: e _in : 100V/div, i _in : 5A/div, time: 10ms/div.

[Eighth Diagram] The first inductor current i _L1 , the second inductor current i _{L2 ,} and the third operation of the AC-DC power converter of the embodiment of the present invention operating at an input voltage of 90 V _rms , an output voltage of 25 V _{DC ,} and an output power of 100 W The analog waveform of the inductor current i _L3 has the scale values of the waveform diagram: i _L1 , i _L2 , i _L3 : 2A/div, time: 10ms/div.

[Ninth aspect] is an analog waveform of a DC link voltage V _c1 and an output voltage V _o when an AC-DC power converter according to an embodiment of the present invention 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 values of the waveform diagram are: V _c1 , V _o : 20V/div, time: 10ms/div.

[Tenth Graph] The waveform of the input voltage e _in and the input current i _in when the AC-DC power converter of the embodiment of the present invention operates at an input voltage of 264 V _rms , an output voltage of 25 V _{DC ,} and an output power of 100 W The scale values are: e _in : 200V/div, i _in : 1A/div, time: 10ms/div.

[Eleventh Image] The first inductor current i _L1 , the second inductor current i _{L2 ,} and the second inductor current i _L1 when the AC-DC power converter of the embodiment of the present invention operates at an input voltage of 264V _rms , an output voltage of 25V _DC, and an output power of 100W. The analog waveform of the three inductor current i _L3 has the scale values of the waveform diagram: i _L1 , i _L2 , i _L3 : 2A/div, time: 10ms/div.

[12th] is an analog waveform of the DC link voltage V _c1 and the output voltage V _o when the AC-DC power converter of the embodiment of the present invention operates at an input voltage of 264V _rms , an output voltage of 25V _DC, and an output power of 100W. The scale values of the waveform diagram are: V _c1 , V _o : 50V/div, time: 10ms/div.

In summary of the above technical features, the main effects of the AC-DC power converter of the present invention will be apparent from the following embodiments.

Referring first to the first figure, a circuit diagram of the AC-DC power converter (1) of the present embodiment includes a front half-stage AC-DC power conversion unit (11) and a second-stage DC-DC power conversion unit (12). ),among them:

The first half-stage AC-DC power conversion unit (11) comprises 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 including four generally polarized general diodes (1131), the arrangement is a bridge type, mainly rectifying the AC voltage input by the AC input voltage terminal (111) into a DC voltage, which is AC- DC conversion. Further, the front half AC-DC power conversion unit (11) operates in a discontinuous conduction mode. The AC input voltage terminal (111) of the first half-stage AC-DC power conversion unit (11) is 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. 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 end of the first diode (115).

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

It should be further noted that the embodiment adopts a single-stage control, and uses a pulse width modulation technique to turn on or off the switch (114) in the driving circuit.

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

For operation, please refer to the second to sixth figures, wherein the third to sixth figures are the 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 a filter circuit (112) is input to the rectifier (113) with a V _S voltage, wherein the AC current is input before the input to the rectifier (113) [the AC input voltage terminal (111), the AC voltage e _in and the filtering The circuit (112) please refer to the first figure], and in the embodiment, when the input voltage of 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, the current path is the arrow in the third figure. Point to the one shown. At this time, the input power source stores energy for 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 stored in series. This mode of operation 1 ends at t=t _k1 , while the switch (114) is now in an off state.

Mode 2: Please refer to the fourth figure and cooperate with the second figure. The operation interval is [t _k1 , t _k2 ]. When the switching relationship (114) is off, the current path is as indicated by the arrow in the fourth figure. 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 mode of operation 2 ends at t=t _k2 , at which point the energy stored in the first inductor (116) is released.

Mode 3: Please refer to the fifth figure and the second figure, the operation interval is [t _k2 , t _k3 ], at this time, the switch (114) is still off state, and its current path is as shown in the fifth figure. The arrow points to the one 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). The operation mode ends when t=t _k3 , and the energy stored in the second inductor (121) and the third inductor (122) is released.

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

Further, referring to the seventh, eighth, and ninth diagrams, the input voltage e _in , the input current i _in , and the input voltage of 90V _rms , the output voltage of 25V _DC , and the output power of 100W are described. An analog waveform 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 . Referring to the tenth, eleventh, and twelfth drawings, the input voltage e _in , the input current i _in , and the operation voltage of the input voltage of 264V _rms , the output voltage of 25V _DC , and the output power of 100W are described. 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 . In the seventh and tenth diagrams, it can be seen from the waveforms of the input voltage e _in and the input current i _in that the AC-DC power converter of the embodiment can achieve a near unit power factor and a low input current total. 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 of the embodiment. The latter half operates 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} smaller than the maximum value of the input voltage, and is much smaller than 450V _DC , which is consistent with Practical principles. And the output voltage V _{o is} stable and can be controlled at 25V to achieve the high step-down ratio function.

In view of the foregoing description of the embodiments, the operation and the use of the present invention and the effects of the present invention are fully understood, but the above described embodiments are merely preferred embodiments of the present invention, and the invention may not be limited thereto. Included within the scope of the present invention are the scope of the present invention.

(1)‧‧‧AC-DC power converter

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

(111)‧‧‧AC input voltage terminal

(112)‧‧‧Filter circuit

(1121)‧‧‧Filter inductor

(1122)‧‧‧Filter Capacitor

(113)‧‧‧Rectifier

(1131)‧‧‧General diodes

(114)‧‧‧Switch

(115) ‧‧‧First Diode

(116)‧‧‧First inductance

(117)‧‧‧First Capacitor

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

(121)‧‧‧second inductance

(122)‧‧‧ Third inductance

(123)‧‧‧Secondary diode

(124)‧‧‧ Third Dipole

(125)‧‧‧Fourth diode

(126)‧‧‧ Output capacitance

(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, wherein the two ends of the AC input voltage are electrically connected to the filter circuit, and the filter circuit is electrically connected to the rectifier, and the rectifier is electrically connected to the first end. One end of the inductor and the cathode end of the first diode, 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 The anode-side of the body; a second-half-level DC-DC power conversion unit electrically connected to the front-half AC-DC power conversion unit, the second-half-level DC-DC power conversion unit includes a second inductor, a third inductor, and a a second diode, a third diode, a fourth diode, an output capacitor, and a load, the cathode end of the fourth diode is electrically connected to the first capacitor The third 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. And 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, and the second inductor end, and the other end of the second inductor is electrically connected a cathode end 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 step-down, and the latter half-stage DC-DC power conversion is performed The conversion of the unit reaches a high step-down ratio. The AC-DC power converter of claim 1, wherein the filter circuit is an LC filter. The AC-DC power converter of claim 1, wherein the rectifier is a full-wave bridge rectifier. The AC-DC power converter of claim 1, wherein the first-stage AC-DC power conversion unit operates in a discontinuous conduction mode. The AC-DC power converter of claim 1, wherein the second-half DC-DC power conversion unit operates in a discontinuous conduction mode. The AC-DC power converter of claim 1, wherein the second inductor and the third inductor are of the same inductance. The AC-DC power converter of claim 1, wherein the second inductor and the third inductor store energy in series when the switch is turned on. The AC-DC power converter of claim 1, wherein the second inductor and the third inductor are parallel-releasing energy when the switch is turned off.