TWI384346B - Power factor correction converter with fast load regulation capability - Google Patents

Description

Power factor correction converter with fast load regulation

The present invention relates to a power factor correction converter, and more particularly to a power factor correction converter having fast load regulation capability.

In recent years, due to the rapid development of science and technology, most electronic products have become increasingly light, thin, short and small, and DC power supply is an important trend of current electronic products. Therefore, a rectifier circuit is needed to convert the commercial AC power to DC power for its use. .

Referring to the first figure, it is a schematic diagram of a conventional single-phase rectification circuit architecture, which includes a bridge rectifier circuit 10 composed of quadrupoles 11, 12, 13 and 14, and an output capacitor C1. Parallel, and the bridge rectifier circuit 10 is further connected with an AC power source P1, and when the AC power source P1 is positive, the input current is transmitted through the diodes 11, 13 and when the AC power source P1 is negative, the input current is passed through the poles. After the bodies 12 and 14 are transmitted, and then filtered by the output capacitor C1, a DC power source can be obtained. Although such a rectifying circuit has the advantage of simple structure, since the bridge rectifying circuit 10 charges the output capacitor C1, it is easy to cause a high surge current, which affects other electric equipment.

Please also refer to the second figure, which is the output voltage waveform generated by the single-phase rectifier circuit of the first figure. It is assumed that the input voltage waveform W1 of the mains is a sine wave, and the output power waveform W2 is dominated by the DC component. The surge current W3 of the bridge rectifier circuit 10 is not a sine wave. In addition to the poor power factor, the surge current also increases the capacity of the component and the wiring circuit, directly increasing the loss of the power supply system and indirectly affecting other users of the same power distribution system.

In view of this, many conventional techniques use power factor correction techniques to improve the above-mentioned lack; wherein the power factor correction technique can be divided into passive and active power factor correction depending on the components. The circuit design of the passive power factor correction is simple, mainly adding a filter circuit composed of an inductor and a capacitor (not shown) between the bridge rectifier circuit 10 and the AC power source P1 to mitigate the surge current to improve the power factor, but this The method of input current total harmonic distortion is high, the volume is too large and the power factor improvement effect is not satisfactory.

Active power factor correction, although the circuit design is more complicated, it is necessary to add switching components to the circuit architecture, and by means of power electronics technology, appropriate control rules are applied to regulate the conduction and cut-off of the active power switch, so that the input power supply current is close. The sine wave follows the input supply voltage, and its power factor can reach above 0.97, and it has the advantages of small size, light weight and low total current harmonic distortion.

Please refer to the third figure, the schematic diagram of the control architecture circuit of the conventional single-phase active PFC dedicated control IC (UCC3854), which mainly uses the voltage dividing resistor 20 to obtain the DC output voltage feedback signal through the voltage amplifier 21 and A DC voltage command V _ref is compared with a voltage error signal A, and then rectified with the diode bridge rectifier 22, and the resistor 23 is used to obtain the input voltage signal B multiplied by the multiplexer 24, thereby obtaining one. A sinusoidal current command that is in phase with the input voltage and that adjusts the magnitude of the amplitude based on load variations. The signal C obtained by the low-pass filter 25 is sent to the multiplexer 24 to be squared, and then divided by the product of the voltage error signal A and the input voltage signal B. This can make the circuit formed by the voltage amplifier 21. The gain remains fixed and its output becomes a power control, which increases the range of variation of the input power supply 26 allowed by the system; then, the sinusoidal current command and the sense resistor are The feedback of the actual input current sensed by 27 is compared with the current amplifier 28, and a current error compensation signal is obtained, and the current error compensation signal is combined with the sawtooth wave or the triangular wave V _s in the pulse width modulator (Pulse). Width Modulation (PWM) 29 compares to obtain a pulse modulation signal, which is converted into a driving signal of the active power switch 31 via a gate driver 30 to control the duty cycle of the power switch 31 (Dudy Cycle). the size of. When the actual input current is greater than the sinusoidal current command, a negative value or a smaller current error compensation signal is obtained by the current amplifier 28 to reduce the duty cycle; otherwise, the duty cycle is increased, so that the input current follows the sinusoidal current command. And the change, and the input power source 26 current and voltage are close to the same phase, to improve the power factor, but the conventional correction circuit still has a number of shortcomings, such as:

(A) Since the control architecture is implemented by hardware, it is easily limited by the characteristics of each circuit component and the error value generated during the process, which makes the implementation of the control strategy difficult.

(B) Please refer to the fourth figure at the same time, because the sinusoidal current command is obtained according to the input voltage signal B sensed by the resistor 23, when the input power source 26 voltage is a non-pure sine wave, at this time, if The current command W4 obtained in the above manner will make it contain harmonic components, so that the actual input power source 26 current has the same harmonic component as the input voltage, and the power factor is affected and the high frequency harmonic of the input power source 26 current is derived. The wave deteriorates the power quality of the power supply system.

(C) The conventional active power factor correction converter will have a second harmonic component of the power supply frequency at the DC output voltage due to the nonlinear characteristic of the rectification filter, and the voltage is usually removed from the voltage to eliminate the influence of the second harmonic. Adding a first-order RC low-pass filter with a bandwidth of about 10~20Hz, which can attenuate the second harmonic in the feedback loop, so that the DC output voltage is stabilized, but the bandwidth is also affected. Limit the situation that the system dynamic response is not good. Therefore, when the DC output voltage is connected to the rapidly changing load, the output voltage will not reach the steady state, and the maximum output overshoot and the depth of the output (Dip) caused by the load fluctuation will increase greatly and indirectly deteriorate. Improvements in power factor and input current harmonics.

Referring to U.S. Patent No. 2006245219, the name of the system is "Digital Implementation of Power Factor Correction", which is mainly implemented by a digital circuit to implement a conventional active power factor correction converter, and reveals a feedback voltage feedforward. Go to the current loop command input to increase the dynamic response of the output voltage.

At the same time, refer to the Patent No. 200423516 of the Republic of China, the title of which is "Power Supply Controller for Sports Equipment Drive Motors", which mainly implements traditional active power factor correction conversion with digital processor. And reveals that the input voltage waveform is read as a basis for modulating the input current waveform.

The object of the present invention is to provide a power factor correction converter with fast load regulation capability, which can keep the current of the input AC power source sinusoidal and in phase with the voltage, that is, the power, during the process of converting the AC power into the DC power source. The factor is close to 壹 or is the control of 壹.

Another object of the present invention is to provide a fast load regulation capability for the DC output voltage to reduce the output voltage from load variations.

The power factor correction converter with fast load regulation capability of the present invention has improved methods for the shortcomings of the prior art:

A. The control strategy proposed by the present invention is implemented by a microprocessor and a software thereof. Since the digital system mainly uses a software algorithm and a logical judgment to implement a control strategy, its strategy modification and parameter adjustment are Compared with the analog control, the flexibility is greatly increased. In addition, the digital system has the advantages of high reliability due to the small number of components and the fact that the signals are all processed through digital processing, which is not easily interfered.

B. The present invention uses an external voltage zero-crossing point detection circuit to detect a digital output pulse signal when the phase of the rectified output voltage is 0 degrees, and generates and inputs a digital pulse through a microprocessor with its built-in counter and software program. The high frequency signal of the wave, and then query the microprocessor's built-in sine wave table to generate a sine wave of 0 to 180 degrees as the basis for calculating the input current waveform of the software; compared with the input power supply current of the present invention The tracking current command is based on detecting the phase of the input power supply voltage instead of its waveform. Please refer to the fifth figure at the same time. Therefore, when the input power supply 26 voltage is a non-pure sine wave, the current command W5 is still A sinusoidal waveform, this can effectively improve the harmonic distortion of the current waveform caused by the input voltage harmonic components; in addition, the method of detecting the voltage waveform from the rectified output can also simplify the microprocessor built-in sine wave table Length and computational complexity to improve system reliability and reduce cost; voltage measurement at this point can also simplify circuit design directly to the microprocessor and measurement circuit to DC The output voltage is connected to a common reference ground potential.

C. In order to improve the shortcomings of the dynamic response of the prior art, the present invention proposes a robust controller design to enhance the system's ability to suppress load disturbances, because when the DC output side is connected to a rapidly varying load, such as when the load is a motor drive, Provides a more stable DC output voltage requirement. The present invention applies an output current through a suitably designed high-pass filter to obtain a suitable transient compensation signal as an additional command to be added to the current loop to provide additional current required to compensate for the load disturbance. When the disturbance is over, the transient compensation signal is also It will automatically disappear and the system control will return to the normal voltage loop parameters.

First, please refer to the sixth embodiment, which is a schematic diagram of a circuit architecture according to a preferred embodiment of the present invention. The architecture of the present invention is a step-up AC-DC converter, and the circuit includes at least one input power source 41 and one rectifier 42. A power factor correction component 43, a power switch 44, a diode 45, an energy storage component 46, a voltage sensing unit 47, and a gate driver 48. In the preferred embodiment of the invention, the rectifier 42 is In the diode bridge rectifier, the power factor correction component 43 is an inductor, and the voltage sensing unit 47 includes two voltage dividing resistors 471 and 472 connected in series, and the connection between the above components and the habit Knowing the same technology, it will not be described.

Please also refer to the seventh figure, which is a waveform diagram generated by the step-down circuit and the zero-crossing point detecting circuit of the present invention. According to the requirements of the present invention, the circuit further includes a load 49 and a first The current sensing unit 50, a microprocessor 60, a second current sensing unit 70 and a zero-crossing point detecting unit 80 are connected in series with the first current sensing unit 50 and further connected in parallel. The opposite ends of the voltage dividing resistors 471, 472, and the opposite ends of the voltage dividing resistors 471, 472 define a DC output voltage Vo, which is used in the preferred embodiment of the present invention. The unit 50 is a resistor or a Hall sensing component, so that it can be used to obtain the current when the load 49 changes. Moreover, the microprocessor 60 is respectively associated with the load 49, the voltage sensing unit 47, and the The gate driver 48, the second current sensing unit 70, and the zero-crossing point detecting unit 80 are connected, and the second current sensing unit 70 is reconnected between the rectifier 42 and the power factor correcting component 43. In addition, the zero-crossing point detection unit 80 further includes a step-down power The circuit 81 and the zero-crossing point detecting circuit 82 are connected to the two ends of the rectifier 42 and further connected to the zero-crossing point detecting circuit 82, and the zero-crossing point detecting circuit 82 is further connected to the microprocessor 60, so that the voltage outputted by the rectifier 42 can be stepped down by the step-down circuit 81 to obtain a step-down voltage V1, and the step-down voltage V1 is matched with the zero-crossing point. Detecting the voltage level of the circuit 82, and the reference ground potential of the zero-crossing point detecting circuit 82 is the same as that of the microprocessor 60, and the zero-crossing point detecting circuit 82 drops the step-down circuit 81. The voltage after the voltage is converted into a pulse wave digital signal S1.

The microprocessor 60 further includes a robust controller 61, a voltage controller 62, a sinusoidal signal calculator 63, a current controller 64 and a pulse width modulator 65, wherein: the robust controller 61 has one end Connected between the load 49 and the first current sensing unit 50 by a first analog-to-digital conversion node 611, so that the signal of the load 49 can be converted into a load current i _s and input to the robust controller. 61. The robust controller 61 further includes a properly designed high pass filter 612 and a time delay module 613. The high pass filter 612 is connected at one end to the first analog digital conversion contact 611, and The variable component of the load current i _{s is} taken out, and the other end is connected to the time delay module 613 , and a transient compensation signal i _{r is} generated by the time delay module 613 , so that the dynamic response of the system can be effectively improved, thereby increasing The DC output voltage Vo is suppressed by the load 49, and is connected to the voltage dividing resistors 471, 472 by a second analog-to-digital switching contact 614, and can be measured by the voltage dividing resistor 472. Voltage feed A second analog to digital converter 614 converts the contact to always flow back to the feedback voltage v _fb, and then to a DC voltage by subtracting the current command v * v _fb feedback voltage to obtain a voltage error amount v _e, and the amount of voltage error The v _e is further sent to the voltage controller 62, and a current error compensation signal i _{ref 1 is} calculated, and the voltage error compensation signal i _{ref 1 is added} to the transient compensation signal i _r to obtain a current reference command i _REF, another, and then to a digital input point 631 is connected to the zero-crossing point detection circuit 82 and the sinusoidal signal calculator 63, so that the zero-crossing point acceptable to detect the pulse circuit 82 converts the digital signal S1, and further inputting the pulse wave digital signal S1 to the sine signal calculator 63.

Please refer to the eighth figure, which is a schematic diagram of the calculation process of the sinusoidal signal calculator of the present invention. The sinusoidal signal calculator 63 converts the pulse wave digital signal S1 into an incremental position information via a timer 632. The information is then added to a sine wave table start position 633 to obtain the memory position of the sine wave currently estimated, and the memory position is obtained via a sine wave table 634 to obtain an input current waveform (sin θ) W6. And the rising edge of the pulse wave digital signal S1 resets the position information of the timer 632 to zero, so that the output of the input current waveform W6 exhibits a periodic output of the same frequency as the pulse wave digital signal S1, and the sine is simultaneously The wave table 634 sequentially stores the input current waveform from 0 degrees to 180 degrees from the memory of the lower position, and the input current waveform W6 is multiplied by the current reference command i _{ref to} obtain a sine. The current command i *, and the amplitude of the sinusoidal current command i * can be adjusted according to the load 49. The microprocessor 60 is connected to the second current sensing by a third analog-to-digital conversion contact 635. The unit 70 obtains an actual input current i _fb , and the actual input current i _fb is further subtracted from the sinusoidal current command i * by a current error amount i _e , and the current error amount i _e is controlled by the current The device 64 obtains a current error compensation signal i _{ref 2} , and then generates a pulse modulation signal via the pulse width modulator 65, and is converted into a driving signal by the digital driver 48 via a digital contact 651 to regulate the power. The duty cycle of the switch 44 is large, and when the actual input current l _{fb is} greater than the sinusoidal current command i *, the current controller 64 outputs a negative value or a smaller current error compensation signal to reduce the duty cycle; otherwise, Increasing the duty cycle, so that the actual input current l _fb can be changed with a small error amount following the sinusoidal current command i *, so that the voltage and current of the input power source 41 are in phase to improve the power factor, thereby eliminating In addition to the stable DC output voltage Vo, the current phase of the input power source 41 is further brought closer to the voltage of the input power source 41 to achieve a power factor of 1.

Please also refer to the measured waveform diagram of the AC input voltage of 110V at full load (400W), when the AC voltage of the input power source 41 is 110V/60Hz, the DC output voltage Vo 200V and the load 49 are fully loaded. At 400 W), the input voltage waveform 126 of the input power source 41 and the input current waveform 128 are measured, and the power factor at this time is up to 0.997.

Please refer to the tenth and eleventh figures at the same time, which are the measured waveforms of the step load change (10% to 100% rated load) without the robust controller, and the step load added with the robust control. Measured waveform diagram of variation (10% to 100% of rated load), as apparent from these figures, if the robust controller 61 is applied as a compensation strategy, the output voltage waveform 130 of the DC output voltage Vo generated relative to it The drop depth, maximum overshoot and settling time are all improved, and the input current waveform 128 is relatively improved.

Please also refer to the twelfth figure, which is the measured waveform of the periodic (4Hz) step load variation (10% to 100% rated load) of the robust control of the present invention. It can be seen from the figure that the DC link is The output voltage waveform 130 can be returned to a steady state, and the DC power factor correction converter of the unenhanced controller 61 is out of control under the same test conditions, and the DC link output current waveform 132 is correspondingly generated.

In summary, the present invention has excellent advancement and practicability in similar products, and at the same time, the technical materials of such structures are frequently investigated at home and abroad, and the same structure is not found in the literature. The invention already has the invention patent requirements, and the application is filed according to law.

However, the above-mentioned ones are merely preferred embodiments of the present invention, and the equivalent structural changes of the present invention and the scope of the claims are intended to be included in the scope of the present invention.

[知知]

10. . . Bridge rectifier circuit

11. . . Dipole

12. . . Dipole

13. . . Dipole

14. . . Dipole

20. . . Voltage dividing resistor

twenty one. . . Voltage amplifier

twenty two. . . Diode bridge rectifier

twenty three. . . Resistor

twenty four. . . Multiplexer

25. . . Low pass filter

26. . . Input power

27. . . Sense resistor

28. . . Current amplifier

29. . . Pulse width modulator

30. . . Gate driver

31. . . Active power switch

A. . . Voltage error signal

B. . . Input voltage signal

C. . . Signal

C1. . . Output capacitor

P1. . . AC power

W1. . . Input voltage waveform

W2. . . Output power waveform

W3. . . Surge current

W4. . . Current command

[invention]

126. . . Input voltage waveform

128. . . Input current waveform

130. . . Output voltage waveform

132. . . Output current waveform

41. . . Input power

42. . . Rectifier

43. . . Power factor correction component

44. . . Power switch

45. . . Dipole

46. . . Energy storage component

47. . . Voltage sensing unit

471. . . Voltage dividing resistor

472. . . Voltage dividing resistor

48. . . Gate driver

49. . . load

50. . . First current sensing unit

60. . . microprocessor

61. . . Robust controller

611. . . First analog digital conversion junction

612. . . High pass filter

613. . . Time delay module

614. . . Second analog digital conversion junction

62. . . Voltage controller

63. . . Sinusoidal signal calculator

631. . . Digital input point

632. . . Timer

633. . . Sine wave table start position

634. . . Sine wave table

635. . . Third analog digital conversion junction

64. . . Current controller

65. . . Pulse width modulator

651. . . Digital contact

70. . . Second current sensing unit

80. . . Zero crossover detection unit

81. . . Buck circuit

82. . . Zero crossover detection circuit

Vo. . . DC output voltage

V1. . . Step-down voltage

S1. . . Pulse wave digital signal

W5. . . Current command

W6. . . Input current waveform

The first figure is a schematic diagram of a conventional single-phase rectification circuit architecture.

The second figure is a waveform diagram of the input and output voltages of the single-phase rectifier circuit of the first figure.

The third figure is a schematic diagram of the control architecture circuit of the conventional traditional single-phase active PFC dedicated control IC (UCC3854).

The fourth figure is the waveform diagram generated when the input power supply voltage is a non-pure sine wave.

The fifth figure is a waveform diagram generated when the input power supply voltage of the present invention is a non-pure sine wave.

Figure 6 is a schematic diagram of a circuit architecture of a preferred embodiment of the present invention.

The seventh figure is a waveform diagram generated by the step-down circuit and the zero-crossing point detecting circuit of the present invention.

The eighth figure is a schematic diagram of the calculation flow of the sinusoidal signal calculator of the present invention.

The ninth figure is a measured waveform diagram of the AC input voltage of 110V at full load (400W).

The tenth figure is a measured waveform diagram of the step load variation (10% to 100% rated load) of the present invention without adding a robust controller.

The eleventh figure is a measured waveform diagram of the step load variation (10% to 100% rated load) added to the robust control of the present invention.

The twelfth figure is a measured waveform diagram of the periodic (4 Hz) step load variation (10% to 100% of rated load) added to the robust control of the present invention.

41. . . Input power

42. . . Rectifier

43. . . Power factor correction component

44. . . Power switch

45. . . Dipole

46. . . Energy storage component

47. . . Voltage sensing unit

471. . . Voltage dividing resistor

472. . . Voltage dividing resistor

48. . . Gate driver

49. . . load

50. . . First current sensing unit

60. . . microprocessor

61. . . Robust controller

611. . . First analog digital conversion junction

612. . . High pass filter

613. . . Time delay module

614. . . Second analog digital conversion junction

62. . . Voltage controller

63. . . Sinusoidal signal calculator

631. . . Digital input point

635. . . Third analog digital conversion junction

64. . . Current controller

65. . . Pulse width modulator

651. . . Digital contact

70. . . Second current sensing unit

80. . . Zero crossover detection unit

81. . . Buck circuit

82. . . Zero crossover detection circuit

Claims (8)

A power factor correction converter with fast load regulation capability, which mainly comprises: an input power source, which can provide an AC voltage; a rectifier connected to the input power source and can rectify the input power source into a DC voltage; a power factor correction component is coupled to one end of the rectifier and configured to store or release energy rectified by the rectifier; a power switch is coupled to the power factor correction component and the other end of the rectifier, respectively; The body is connected to the power factor correction component and the power switch at one end, thereby blocking energy back to the rectifier and the power switch with respect to the other side of the input power source; an energy storage component is respectively associated with the diode and The power switch is connected, and defines a DC output voltage at two ends of the energy storage component; a voltage sensing unit is connected in parallel with the energy storage component, and is configured to convert the DC output voltage into an analog input level a signal, one end of which is connected to one end of the DC output voltage; a first current sensing unit, one end of which is connected to The other end of the load is connected to the other end of the DC output voltage to obtain the current when the load changes; a microprocessor having a software program therein and the voltage sensing The unit and the load are connected at one end, and the microprocessor further comprises a robust controller, wherein the robust controller is provided with a suitably designed high-pass filter and a time delay module, and the high-pass filter is terminated at one end. The load is connected, and the other end is connected to the time delay module to improve the dynamic response of the system by using the transient compensation signal obtained by the robust controller, thereby increasing the suppression capability of the DC output voltage on the load disturbance; a gate driver Connected to the power switch and the microprocessor, respectively, and used Converting a pulse modulation signal generated by the microprocessor to drive the power switch; a second current sensing unit having one end connected to one end of the rectifier and the other end connected to the microprocessor; The zero-crossing point detection unit has one end connected to the rectifier and the other end connected to the microprocessor, and is used for detecting the zero voltage of the rectifier output voltage and generating a pulse wave signal synchronized with the zero voltage. The power factor correction converter with fast load regulation capability according to the first aspect of the patent application, wherein the zero-crossing point detection unit further includes a step-down circuit and a zero-crossing point detection circuit, and the The step-down circuit has one end connected to the rectifier, and the other end is connected to the zero-crossing point detecting circuit, and the zero-crossing point detecting circuit is further connected to the microprocessor, and the zero-crossing point detection The measuring circuit can output a pulse wave synchronized with the zero voltage point of the input waveform of the input power source. A power factor correction converter with fast load regulation capability according to claim 2, wherein the microprocessor further comprises a sinusoidal signal calculator, the sine wave signal calculator accepting the zero crossover The pulse signal generated by the point detecting circuit, and the sine wave signal calculator is provided with a sine wave table, and the pulse wave input into the microprocessor can be controlled by the zero crossing point detecting circuit The waveform, and further produces a sine wave in phase with the input power source, and the sine wave generated by the sinusoidal signal calculator ranges from 0 degrees to 180 degrees. The power factor correction converter with fast load regulation capability according to claim 1, wherein the first current sensing unit is a resistor. The power factor correction converter with fast load regulation capability according to claim 1, wherein the first current sensing unit is a Hall sensing element. A power factor correction converter with fast load regulation capability according to claim 1 of the patent application scope, wherein the transient compensation signal calculated by the robust controller is calculated by a voltage controller connected to the voltage sensing unit Current error compensation signal mixing Calculating, at the same time, subtracting from an actual input current obtained by the second current sensing unit, and obtaining a current error amount, and the current error amount is further adjusted by a current controller and a pulse width a transformer to drive the gate driver to regulate the power switch. A power factor correction converter with fast load regulation capability according to claim 1 of the patent application, wherein the power factor correction component is an inductor. The power factor correction converter with fast load regulation capability according to claim 1, wherein the voltage sensing unit further comprises a voltage dividing resistor, wherein the voltage dividing resistors are connected in series, and At the same time, the microprocessor is further connected between the voltage dividing resistors.