TWI424668B - Buck-boost based power factor correction converter with positive dc output-voltage - Google Patents

Description

Drop-down power factor correction power converter with positive output voltage

The present invention relates to a power converter, and more particularly to a step-down type power factor correction power converter having a positive output voltage.

Referring to Figure 1, there is shown a circuit diagram of a conventional boost type power factor correction power converter. The conventional boost type power factor correction power converter 10 includes a full bridge rectifier 11, an inductor 12, a switch 13, a diode 14 and a capacitor 15. The conventional boost type power factor correction power converter 10 operates in a continuous current conduction mode, and has the advantages of simple structure and high power factor, but its output voltage can only be higher than the input voltage, and the application range is limited.

Referring to Figure 2, there is shown a circuit diagram of a conventional SEPIC power factor correction power converter. The conventional SEPIC power factor correction power converter 20 includes a full bridge rectifier 21, a first inductor 22, a switch 23, a first capacitor 24, a second inductor 25, a diode 26 and a second capacitor. 27. The conventional SEPIC power factor correction power converter 20 can be applied to a wide input voltage range, but since the conventional SEPIC power factor correction power converter 20 operates in a continuous current conduction mode, the switching loss caused by the power switch 23 in the circuit also follows the switching. The frequency increases and the circuit efficiency decreases, and the product volume cannot be effectively reduced.

Therefore, it is necessary to provide an innovative and progressive step-down power factor correction power converter to solve the above problems.

The invention provides a step-down power factor correction power converter with a positive output voltage, comprising: a rectifier, a first switch, a first diode, an inductor, a second switch and a second Diode. The rectifier is used to rectify an AC power source. The first switch is connected to the rectifier, and the first switch is turned on at zero current and has a fixed on-time. The first diode is connected to the first switch. The inductor is coupled to the first switch and the first diode, and the current on the inductor operates in a critical current mode. The second switch is connected to the inductor, and the second switch is turned on at zero current and has a fixed on-time. The second diode connects the second switch and the inductor.

The step-down power factor correction power converter of the invention can achieve a wide input voltage range and a positive output voltage that can be boosted or stepped down, and the switching element has a zero current conduction characteristic, which can improve the circuit switching frequency and narrow the energy storage component. It is high in efficiency when used in high frequency applications; it also reduces input current harmonics and simplifies the complexity of the drive circuit.

Referring to Fig. 3, there is shown a circuit diagram of a step-down type power factor correction power converter of the first embodiment of the present invention. A step-down power factor correction power converter 30 having a positive output voltage includes a rectifier 31, a first switch 32, a first diode 33, an inductor 34, and a second The switch 35 and a second diode 36. The rectifier 31 is for rectifying an AC power source V _ac (t). In this embodiment, the rectifier 31 is a full bridge rectifier.

The first switch 32 is connected to the rectifier 31. The first switch 32 is turned on at zero current and has a fixed on-time. The first diode 33 is connected to the first switch 32. The inductor 34 is connected to the first switch 32 and the first diode 33, and the current on the inductor 34 operates in a critical current mode. The second switch 35 is connected to the inductor 34. The second switch 35 is turned on at zero current and has a fixed on-time. The second diode 36 is connected to the second switch 35 and the inductor 34. The step-down power factor correction power converter 30 of the present invention further includes a capacitor 37 connected to the second diode 36.

Referring to Fig. 4, there is shown a circuit diagram of a step-down type power factor correction power converter of a second embodiment of the present invention. In addition to the components of the step-down power factor correction power converter 30 of the first embodiment described above, the second embodiment of the present invention has a positive output voltage drop-down type power factor correction power converter 40 further including a filter circuit 41. The high frequency current waveform used to input the input end of the rectifier 31 is rectified into a sinusoidal current waveform.

Referring to Fig. 5, there is shown a circuit diagram of a step-down type power factor correction power converter of a third embodiment of the present invention. In addition to the components of the step-down power factor correction power converter 30 of the first embodiment described above, the third embodiment of the present invention has a positive output voltage drop-down type power factor correction power converter 50 further comprising: a zero current The detecting circuit 51, a logic determining and driving circuit 52, a first proportional circuit 53, a second proportional circuit 54, a voltage error amplifier 55, a multiplier circuit 56, a detecting resistor 57 and a current comparator 58 .

Referring to FIG. 6, there is shown a schematic diagram of component signal waveforms of a step-down power factor correction power converter according to a third embodiment of the present invention. A circuit operation of a step-down power factor correction power converter having a positive output voltage according to a third embodiment of the present invention will be described with reference to Figs. 5 and 6. The zero current detecting circuit 51 is connected to the inductor 34 for detecting whether the current value of the inductor 34 is zero, and outputting a zero current signal to the logic determining and driving circuit 52. In this embodiment, the zero current detecting circuit 51 detects whether the voltage V _ZCD of the second measurement of the inductor 34 is zero.

The logic determining and driving circuit 52 is connected to the zero current detecting circuit 51, and the first switch 32 and the second switch 35 are controlled to be turned on according to the zero current signal. That is, when the zero current detecting circuit 51 detects that the second measured voltage V _{ZCD of the} inductor 34 decreases to zero, the first switch 32 and the second switch 35 are synchronously controlled to be turned on. Therefore, when the first switch 32 and the second switch 35 are turned on, the current flowing through the inductor 34 and the first switch 32 and the second switch 35 are both zero, so that the current is zero-conducting.

The first proportional circuit 53 is connected to the rectifier 31 for multiplying a rectified signal by a first set ratio K _in . The second proportional circuit 54 is connected to the DC output terminal for multiplying the DC output signal _Vo by a second set ratio K _o . The voltage error amplifier 55 is connected to the second set ratio DC output signal of the second proportional circuit 54 and a set voltage (for example, 2.5V), and outputs a voltage error amplification signal B. The multiplier circuit 56 is configured to multiply the first set ratio rectification signal A by the voltage error amplification signal B and output a reference voltage V _ref . The detecting resistor 57 is connected to the second switch 35 and obtains a detecting resistor voltage V _CS . The current comparator 58 is configured to compare the reference voltage V _ref and the detection resistor voltage V _CS and output a comparison signal to the logic determination and driving circuit 52.

When the first switch 32 and the second switch 35 are turned on, the input power source (the rectified rectified signal V _in (t)) charges the inductor 34, so that the inductor current value i _L1 (t) rises, and the resistance voltage V is detected. _CS also rose. When the detecting resistor voltage V _CS rises to be the same as the reference voltage V _ref , the current comparator 58 outputs a comparison signal to the logic determining and driving circuit 52, and the logic determining and driving circuit 52 synchronously controls the first signal according to the comparison signal. A switch 32 and the second switch 35 are turned off. When the first switch 32 and the second switch 35 are turned off, the inductor 34 discharges to the load, causing the inductor current value i _L1 (t) to decrease, and the second measured voltage V _{ZCD of the} inductor 34 to decrease. When the second measured voltage V _{ZCD of the} inductor 34 decreases to zero, the logic determining and driving circuit 52 synchronously controls the first switch 32 and the second switch 35 to be turned on again.

The multiplier circuit 56 has two functions, one is to detect the peak value of the input voltage, so that the inductor current can follow the voltage peak, thereby achieving the power factor correction function. The second is to detect the output voltage level level, and then adjust the output voltage level to achieve the output voltage regulation function. In addition, the on-times of the first switch 32 and the second switch 35 are controlled by the zero current detecting circuit 51 and the multiplier circuit 56, so that they have a constant on-time characteristic.

Referring to FIG. 7, a schematic diagram of an experimental measurement waveform of a first switch and a second switch drive signal and an inductor current of the step-down power factor correction power converter of the present invention is shown. Observing the waveform, the first switch and the second switch drive signal V _gs,1 (t), V _gs,2 (t) are turned on, and the inductor current i _L1 (t) is negative, so the first switch can be made. And the second switching element has a zero current conduction characteristic, thereby increasing the circuit switching frequency and reducing the volume of the energy storage element.

Referring to FIG. 8, there is shown a waveform diagram of experimental measurements of input voltage, input current and output voltage at the rectifier terminal of the step-down power factor correction power converter of the present invention. As can be seen from the waveform, when the input voltage V _{in the} rectifier terminal is 170V, the output voltage V _o is 120V, and the input current i _in is 460mA; when the input voltage V _{in the} rectifier terminal is 80V, the output voltage V _o is 120V, And the input current i _in is 980 mA. Referring to FIG. 9, there is shown a waveform diagram of an input AC power supply voltage, an input AC power supply current, and an output DC voltage experimental measurement of the step-down power factor correction power converter of the present invention. As can be seen from the waveform, when the input AC power supply voltage V _ac is 90 V, the output DC voltage V _o is 220 V; when the input AC power supply voltage V _ac is 264 V, the output DC voltage V _o is 220 V. Therefore, the step-down power factor correction power converter of the embodiment of the present invention has a high power factor when applied to a higher or lower input voltage (80V~170V) or (90V~264V). That is, the step-down power factor correction power converter of the present invention can achieve a wide input voltage range and a positive output voltage that can be boosted or stepped down.

Referring to FIG. 10, there is shown a schematic diagram comparing the odd-order input current harmonic values of the step-down power factor correction power converter of the present invention with the IEC 61000-3-2 Class-D international standard specification. FIG. 10 shows that the present invention The step-down power factor correction power converter can effectively reduce the input current harmonics and conform to international standards.

Therefore, the step-down power factor correction power converter of the present invention can achieve a wide input voltage range and the output voltage can be boosted or stepped down, and the switching element has a zero current conduction characteristic, which can improve the circuit switching frequency and reduce the energy storage component. It is high in efficiency when used in high frequency applications; it also reduces input current harmonics and simplifies the complexity of the drive circuit.

However, the above embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the spirit of the invention. The scope of the invention should be as set forth in the appended claims.

10. . . Conventional boost type power factor correction power converter

11. . . Full bridge rectifier

12. . . inductance

13. . . switch

14. . . Dipole

15. . . capacitance

20. . . Conventional SEPIC Power Factor Correction Power Converter

twenty one. . . Full bridge rectifier

twenty two. . . First inductance

twenty three. . . switch

twenty four. . . First capacitor

25. . . Second inductance

26. . . Dipole

27. . . Second capacitor

30. . . First embodiment step-down power factor correction power converter

31. . . Rectifier

32. . . First switch

33. . . First diode

34. . . inductance

35. . . Second switch

36. . . Second diode

37. . . capacitance

40. . . Second Embodiment Down-Boost Power Factor Correction Power Converter

41. . . Filter circuit

50. . . Third embodiment step-down type power factor correction power converter

51. . . Zero current detection circuit

52. . . Logical judgment and drive circuit

53. . . First proportional circuit

54. . . Second proportional circuit

55. . . Voltage error amplifier

56. . . Multiplier circuit

57. . . Detecting resistance

58. . . Current comparator

1 shows a circuit diagram of a conventional boost type power factor correction power converter;

2 is a circuit diagram showing a conventional SEPIC power factor correction power converter;

3 is a circuit diagram showing a step-down power factor correction power converter of a first embodiment of the present invention;

4 is a circuit diagram showing a step-down power factor correction power converter of a second embodiment of the present invention;

5 is a circuit diagram showing a step-down power factor correction power converter of a third embodiment of the present invention;

6 is a schematic diagram showing the waveforms of component signals of a step-down power factor correction power converter according to a third embodiment of the present invention;

7 is a schematic diagram showing experimental measurement waveforms of a first switch and a second switch driving signal and an inductor current of the step-down power factor correction power converter of the present invention;

8 is a schematic diagram showing waveforms of experimental measurements of input voltage, input current, and output voltage at a rectifier terminal of a step-down power factor correction power converter of the present invention;

9 is a schematic diagram showing waveforms of an input AC power supply voltage, an input AC power supply current, and an output DC voltage experimental measurement of the step-down power factor correction power converter of the present invention;

FIG. 10 is a schematic diagram showing the comparison of the odd-order input current harmonic values of the step-down power factor correction power converter of the present invention with the IEC 61000-3-2 Class-D international standard specification.

30. . . First embodiment step-down power factor correction power converter

31. . . Rectifier

32. . . First switch

33. . . First diode

34. . . inductance

35. . . Second switch

36. . . Second diode

37. . . capacitance

Claims (6)

A step-down power factor correction power converter having a positive output voltage, comprising: a rectifier for rectifying an AC power source; a first switch connected to the rectifier, the first switch being turned on at zero current, and a fixed on-time; a first diode connected to the first switch; an inductor connected to the first switch and the first diode, the current on the inductor is operated in a critical current mode; a second switch Connecting the inductor, the second switch is turned on at zero current, and has a fixed on-time; and a second diode is connected to the second switch and the inductor. A boost-down power factor correction power converter as claimed in claim 1, wherein the rectifier is a full bridge rectifier. The step-down power factor correction power converter of claim 1 further comprising a filter circuit for rectifying the high frequency current waveform at the input of the rectifier into a sinusoidal current waveform. The step-down power factor correction power converter of claim 1, further comprising a capacitor connected to the second diode. The step-down power factor correction power converter of claim 1, further comprising: a zero current detecting circuit connected to the inductor for detecting whether the current value of the inductor is zero, and outputting a zero current signal; A logic determining and driving circuit is connected to the zero current detecting circuit, and the first switch and the second switch are controlled to be turned on according to the zero current signal. The step-down power factor correction power converter of claim 5, further comprising: a first proportional circuit connected to the rectifier for multiplying a rectified signal by a first set ratio; and a second proportional circuit connecting a DC output terminal for multiplying the DC output signal by a second set ratio; a voltage error amplifier connecting the second set ratio DC output signal of the second proportional circuit and a set voltage, and outputting a voltage error Amplifying signal; a multiplier circuit for multiplying the first set ratio rectification signal by the voltage error amplification signal and outputting a reference voltage; a detecting resistor, connecting the second switch, and obtaining a detecting resistance voltage a current comparator for comparing the reference voltage and the detection resistor voltage, and outputting a comparison signal to the logic determination and driving circuit; wherein the logic determining and driving circuit synchronously controls the first switch according to the comparison signal The second switch is turned off.