TW200427374A - Electronic ballast with crest factor correction - Google Patents

Abstract

Low cost electronic ballast does not have a function of crest factor correction in those conventional arts, and so a life span of a fluorescent lamp using the electronic ballast decreases due to a high crest factor correction. In the present invention, it provides a low cost electronic ballast controller that varies an operating frequency according to a feedback voltage to control a lamp current for achieving an objective of crest factor correction.

Description

200427374 ^^ V. Description of the invention (1) [Technical field to which the invention belongs] The present invention is related to electronic ballasts, especially to electronic ballasts with crest factor correction. 2. [Previous technology] The definition of the Crest Factor (CF) of the lamp current of a fluorescent lamp refers to the peak current generated by the lamp current envelope when an electronic ballast is used to light a fluorescent lamp. The ratio of the rms value of the current (the root mean square value of the current-the RMS value). However, many high-frequency vibrations are hidden in the general AC current waveform, causing the crest factor of the actual situation to be higher than the ideal value of 1 · 4 1 4. The value of this crest factor has a direct and significant impact on the life of the lamp. Most lamp manufacturers recommend that this value is preferably less than 丨 · 7. Excessively high values can easily cause blackening of the lamp. Reduce the life of the lamp. ° β 'Electronic ballasts generally require high power factor correction (PFC) in order to improve the efficiency of power generation of electronic ballasts. However, additional power equipment will increase the difficulty of manufacturing electronic ballasts and increase the cost of electronic ballasts, and most of these cost burdens will be passed on to users. So for many electronic ballast engineers, the main task is to develop a cost-effective power factor correction method.

Page 7 200427374 V. Description of the invention (2) The first power factor is shown in Figure 10. The 10 represents a boost type body. The harmonic factor of the Conduc cycle can be controlled to restore the second high 0 factor factor correction circuit. There are two basic types. : One is an active number correction circuit; the other is a passive power factor correction circuit. A traditional active power factor correction circuit is shown, in which a Bridge Rectifier is used. This circuit uses a boost circuit (Boost Topol ogy) and a high frequency switching field effect transistor to operate in a continuous inductive current or a critical conduction mode (CRI) mode. Before starting a new charge, The inductance L 1 allows the energy to be released to zero. This circuit can be fully filled 'and therefore a high power factor can be achieved. This type of power positive circuit can achieve a power factor of up to 99%. However, the material cost of the PFC, inductor L1, high-speed power field effect transistor w, and fast polar body D1 'is quite passive. The power factor correction circuit uses only passive components, so its cost is lower than that of the active type. Power factor correction circuit. The second figure shows a simple LC passive power factor correction circuit. This type of circuit operates at low frequency " (50 Hz or 60 Hz) and uses and uses a silicon steel sheet inductor (PFC Choke) L1 and capacitor ^ as a low-pass or band-pass filter for low-frequency operation Architecture (Low Pass or Band Pass Filter

Configuration). Unfortunately, because the circuit operates at low frequency, its LC circuit requires large inductance and capacitance values, especially the physical size and weight of the inductor [丨 are quite large, and it will cause disturbing beeps when used.

200427374 V. Explanation of Invention (3) Sound. Therefore, although passive power factor correction circuits can achieve good performance, currently this type of circuit is rarely used. Currently, there is a need for a low-cost power factor correction circuit, for example, a power factor correction circuit (Valley Fill PFC Circuit) with a flat circuit. The third diagram A shows a power factor correction circuit with a flat circuit that can achieve a high power factor (93% -95%). In this circuit, the filter capacitors C1, C2 each half cycle of the rectified AC input Charge in series through diode D2, and charge to half the AC peak voltage (assuming that the diode is an ideal diode and there is no voltage across the diode). When capacitors C1 and C2 have been charged to half of the AC peak voltage, the output current is provided by capacitors Cl and C2 only when the voltage of the DC line φ drops below half of the AC peak voltage with a sine waveform. During the output current process, capacitors C1 and C2 provide the load current in a parallel state until the rectified AC voltage value is higher than the capacitor voltage again in the next cycle. Ideally (assuming that the capacitance of the capacitor is large, the capacitor The voltage does not drop after discharge), this value is half the AC peak voltage value, and the voltage waveform of the DC output is as shown in Figure 3B. It can be known through the simple nose counting that the time when the value of the sine wave V-shape that changes with the time axis of the follower is less than half of the maximum value is about 37% of the total time. This value is also the working cycle rate of the capacitor ( Duty Cycle) value. The remaining 63% of the capacitor's idle (I d 1 e) time is directly provided by the rectified AC input. This architecture can greatly increase power quality and power stomach factor. However, the biggest disadvantage of a power factor correction circuit with a flat circuit is that it has a large ripple voltage, which is about AC input.

Page 9 200427374 V. Description of the invention (4) Half of voltage. Any use of such electronic ballasts without correcting the lamp current will result in considerable crest factor values. Most of the half-bridge field-effect transistor (MOSFET) drivers or controllers used in electronic ballasts for fluorescent lamps have low cost but do not have the function of adjusting the lamp current. In most cases, after the timing capacitor and resistor are determined, the operating frequency of the driver is set. The field-effect transistor drives or electronic ballasts using low-cost controllers do not adjust the lamp current. Therefore, when the voltage of the DC bus (DC bus) changes, the lamp current also changes with the DC voltage ripple (D C r i p p 1 e). This may cause the crest value of the lamp current to exceed 1.7 and reduce the service life of the lamp. Therefore, it is not suitable to use a power factor correction circuit with a flat circuit for a low-cost stability controller without a current adjustment capability. The fourth diagram A shows a typical electronic ballast using a power factor correction circuit with a flat circuit, where 20 represents a half-bridge MOSFET driver, 30 represents a lamp tube, and fourth diagram B The current waveform of lamp 30 is shown. 7。 Because the lamp current is not corrected, the crest factor of the lamp current will easily be higher than 1.7. III. [Content of the invention] In view of the above background of the invention, the low-cost, high-power-factor electronic ballast with known techniques has no crest factor current correction function, and the stomach causes a high crest factor to affect the service life of the lamp. . Or the cost of a high power factor electronic ballast with crest factor current correction

Page 10 200427374 V. Description of the invention (5) Quite high. The main purpose of the present invention is to provide a simple and low-cost electronic stability controller, which has the function of crest factor correction under high DC voltage ripple, so as to effectively extend the service life of the lamp tube. Another object of the present invention is to reduce the crest factor of the lamp current by correcting the crest factor of the current using an electronic stabilizer controller. According to the above-mentioned object, the present invention provides an electronic ballast. The electronic ballast includes a full-wave rectifier circuit, a converter, a power factor correction circuit, a voltage signal generator, a controller, and an LC oscillator circuit. When a rectified voltage rises, the converter increases the oscillating frequency of the output AC voltage according to the switching signal of one of the control φ devices, so that the current flowing through the oscillating inductance of the LC oscillating circuit is suppressed, and when the rectified voltage decreases, the converter The device reduces the oscillation frequency according to the switching signal, so that the reduction of the current flowing through the oscillation inductor is reduced. The invention also provides an electronic ballast with a crest factor correction for a fluorescent tube. The electronic ballast with crest factor correction for a fluorescent tube includes a full-wave rectifier circuit, a converter, a flat circuit, a voltage signal generator, a controller, and an LC oscillator circuit. When a rectified voltage rises, the converter switches the signal according to one of the controllers to increase the oscillation frequency of the output AC voltage, so that the current flowing through the oscillating inductor of the LC oscillating circuit is suppressed, and when the rectified voltage decreases, the converter The device reduces the oscillation frequency according to the switching signal, so that the current flowing through the oscillation inductor

Page 11 200427374 V. Description of the invention (6) The decrease is reduced. Compared with the low cost, high power factor electronic ballasts of the conventional technology, the lack of crest factor current correction function results in a high crest factor and affects the life of the lamp. Or a high power factor electronic ballast with a crest factor current correction function is quite expensive. In the present invention, the voltage feedback signal is used to adjust the operating frequency of the electronic ballast, and the lamp current can be controlled simply by changing the operating frequency. Therefore, with a simple and low-cost electronic stabilizer controller, the electronic stabilizer has the function of crest factor correction under high DC voltage ripple to effectively reduce the crest factor of the lamp current and extend the lamp's Service life. 4. [Embodiments] Some embodiments of the present invention will be described in detail as follows. However, in addition to the detailed description, the present invention can be widely implemented in other embodiments, and the scope of the present invention is not limited, which is subject to the scope of subsequent patents. Furthermore, in order to provide a clearer description and easier understanding of the present invention, the parts in the drawings have not been drawn according to their relative dimensions, and certain dimensions have been exaggerated compared to other related scales; irrelevant details have not been completely drawn. Out for simplicity of the diagram. For electronic ballasts, the most cost-effective topological circuit diagram is

Page 12 200427374 V. Description of the invention (7) Half-bridge LC. Resonant circuit (Half · 』τ ^ ·). The fifth figure shows a half-bridge LC resonant circuit using a ResOntant circuit according to the present invention. ^ The power factor correction of a flat circuit 40 represents a low-cost one with a preferred embodiment, in which resistance and R3 are connected in series. Let the power of the controller Y be the positive power socket of the controller Y. The voltage Θ ^ of the electrical appliance 40 provides a divided voltage at point A as a control to provide this voltage back < "VFB 'can also use any voltage signal generator to the signal generator ::: / Β' but with a series resistor circuit The resulting voltage and voltage field efficiency is the lowest. The second half of this circuit is a half-bridge SDC / AC converter composed of two high-controllers 40 = batch w. The endpoints Hi and Lo enable two high-voltage field-effect transistors Q1 and Q2 3 0. An electronic stability controller that can convert DC to AC power to drive lamp parts to achieve peak-to-peak number correction with ^ point switching '4 0 uses the least system. At this point, the k lamp officer starts (LaiDP Igni ti0n) and the lamp current limit L, C4. ^ Flutter circuit 'by operating the switching frequency to close to the resonance tank after starting, vibrating Frequency, so that the LC resonance circuit can start the lamp 30. In proportion to the operation of L, it can be used as the current limiting element of the lamp. The impedance of the inductor feeds the mirror Vp, and the frequency. Therefore, when the voltage of the DC link rises, The voltage returned to Xunmai ^ The voltage also increased, and the controller 4 received the DC link power. The effect is to increase the switching rate of the field-effect transistors Q 1 and Q 2 by using Tigu L. The effect of S Γ can increase the impedance of the inductor and reach the voltage that suppresses the current. When the voltage of the chain is reduced, the voltage feedback signal vF will limit the reduction. The controller 40 receives a message that the DC chain voltage is reduced to reduce the switching speed of the high-voltage field-effect transistors Q1 and Q2.

Page 13 200427374 V. Description of the invention (8) The operating frequency can reduce the impedance of the inductor and slow down the reduction of the lamp current. Therefore, the lamp current can be controlled simply by changing the operating frequency. Figure 6 shows a simple block diagram of an electronic stability controller with crest factor correction. The voltage V dd is the positive power supply voltage of the controller. The input voltage can be adjusted by the band reference 50. When the voltage vdd is too high, the Zona plant D4 is turned on to limit the voltage. When the voltage Vdd is too low, the low voltage The lock 60 prevents malfunction when the voltage is too low. The high-level driver 80 and the low-level driver 100 provide switching signals Hi and L0. The signals Vs, Hi and Lo are used as driving signals of the half-bridge field effect transistors (such as Q 丨 and Q2 in the fifth figure).

The start control 1 20 is performed at a resonance frequency higher than the Lc oscillator circuit, and then starts the lamp at an operating frequency close to the resonance frequency. V Protection logic light two = 1 3 0 is a protection logic controller of the conventional art. The protection ballast has the function of closing the ballast during operation. Voltage control shock surplus 丨 丨 〇 Accept voltage feedback

‘5 震 生 震 堡 frequency input control logic 9 0. The level conversion 7 0 uses the C conversion control logic 9 0 kit to describe the potential of each of the functional circuits 50 signal to the potential of the driving voltage ° ”and 1 q η village -r ± 〇, 60, 70, 80, 90, 1 〇〇, 110, 120, and 130 can use the functional circuits in the conventional art. Current, voltage ripple voltage feedback V- to adjust the factor of the lamp and R 3 series resistance. 1 When the voltage of the DC link rises, the 'R2 feed voltage VFB also rises and rises.' 7 The voltage rises, so Return frequency input via point A. Therefore, the voltage controller oscillator 1 1 0 at this time increases the impedance of the operation " and the impedance of the lamp also increases to suppress the lamp current. phase

200427374 V. Description of the invention (9) Conversely, when the voltage of the DC link decreases, the cross-voltage across the series resistance of R2 and R3 decreases, so the feedback voltage Vfb input through point A will also decrease. At this time, the voltage controller The oscillator 1 10 reduces the operating frequency to ease the decrease of the lamp current. After adjusting the frequency, the output current waveform is as shown in Figure 7. The higher and lower parts of the current have been eliminated, so the crest factor can be effectively reduced. The preferred variable frequency range of the present invention is 50 kHz to 8 Ok Hz. With this method, the system can easily reduce the crest factor value to less than 1.70. Compared with the conventional technique, the present invention has many features that are not found in the conventional technique. The ballast system shown in Figure 6 is a fairly low cost solution. In this circuit, the lamp current is not controlled by the lamp current feedback of the subsequent stage. On the contrary, the voltage feedback Vfb of the DC link of the previous stage is used as a control signal to adjust the lamp current. Current feedback of conventional memory Generally, the feedback signal of the lamp current (AC) needs to be converted into a DC voltage feedback signal, and additional components are needed to obtain the current feedback signal and convert it into a voltage signal. Therefore, the voltage feedback signal is easier to obtain and use than the current feedback. The controller 40 obtains the feedback voltage VFB of the DC link and adjusts the operating frequency to adjust the lamp current to reduce the crest factor. In addition, unlike the conventional electronic ballast with a function of adjusting lamp current, the present invention does not require an expensive closed loop (C 10 s e-L ο ο p) control system. The main purpose of the present invention is to reduce the crest factor of the lamp current, instead of strictly controlling the current of the lamp current, so no expensive closed-loop control system is needed. Since this is a

Page 15 200427374 V. Explanation of the invention (10) The open loop (0 p e η-L ο ο p) system does not need to pay attention to the problem of instability like the closed loop. Many vendors of traditional half-bridge field-effect transistor drivers or low-cost ballast controllers suggest discontinuous solutions to this problem. This solution requires an additional part to provide a stepped operating frequency change to the crest factor correction. However, this discontinuous system has higher cost and unsatisfactory performance. On the other hand, the system of the present invention is a integrated circuit and provides a reliable solution for the linear continuous adjustment of the lamp current based on voltage feedback. Therefore, the present invention provides a reliable solution with low cost and higher performance. In summary, the present invention discloses an electronic ballast. The electronic ballast includes a full-wave rectifier circuit, a converter, a power factor correction circuit, a voltage signal generator, a controller, and an LC oscillator circuit. When a rectified voltage is increased, the converter increases the oscillating frequency of the output AC voltage by switching signals according to one of the controllers, so that the current flowing through the oscillating inductance of the LC oscillating circuit is suppressed, and when the rectified voltage is reduced, the converter Reduce the oscillation frequency according to the switching signal, so that the reduction of the current flowing through the oscillation inductor is reduced. The invention also discloses an electronic ballast with a crest factor correction for a fluorescent tube. This electronic ballast with crest factor correction for a fluorescent tube includes a full-wave rectifier circuit, a converter, a flat

Page 16 200427374 V. Description of the Invention (11) Circuit, a voltage signal generator, a controller and an LC oscillator circuit. When a rectified voltage is increased, the converter increases the oscillating frequency of the output AC voltage according to a switching signal of the controller, so that the current flowing through the oscillating inductance of the LC oscillating circuit is suppressed. _ Reduce the oscillation frequency according to the switching signal, so that the reduction of the current flowing through the oscillation inductor is reduced. Compared with the low cost, high power factor electronic ballasts of the conventional technology, the lack of crest factor current correction function results in a high crest factor and affects the life of the lamp. Or a high power factor electronic ballast with a crest factor current correction function is quite expensive. In this issue, φ Ming uses the voltage feedback signal to adjust the operating frequency of the electronic ballast. By changing the operating frequency, the lamp current can be easily controlled. Therefore, with a simple and low-cost electronic stabilizer controller, the electronic stabilizer has the function of crest factor correction under high DC voltage ripple to effectively reduce the crest factor of the lamp current and extend the lamp's Service life. The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of patent application of the present invention; all other equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall be included in the following The scope of patent application. _

Page 17 200427374 The diagram is a simple illustration. The first diagram is a schematic diagram of the active power factor correction circuit in the conventional art; the second diagram is the schematic diagram of the passive power factor correction circuit in the conventional art; 4 The third A and three B diagrams A schematic diagram of a power factor correction circuit with a flat circuit in the conventional art and its output voltage waveform; Figures 4A and 4B are schematic diagrams of an electronic ballast with a power factor correction circuit with a flat circuit in the conventional art and a lamp thereof. The current waveform; the fifth diagram is a schematic diagram of a circuit of an electronic stabilizer according to a preferred embodiment of the present invention; the sixth diagram is a block diagram of the electronic stability controller with crest factor correction of the present invention; and the seventh The figure shows the lamp current waveform of the electronic ballast of the present invention. Representative symbols of the main parts · 1 0 Rectifier 2 0 Driver _ 30 Lamp _ 40 Controller 50 Can bring the reference circuit

Page 18 200427374 Brief description of drawings 60 Low voltage lock circuit 70 Level switching circuit 80 High potential driver 90 Control logic circuit 100 Low potential driver 110 Voltage controlled oscillator 120 Warm-up start controller 130 Protection logic controller D1, D4 Diode R1 strict, R3 resistance C1 ~ C4 capacitor L, LI inductor Q1, Q2 transistor ❶

Page 19

Claims (1)

200427374 VI. Application for patent scope 1. An electronic ballast with crest factor correction for a fluorescent tube, comprising: a full-wave rectifier circuit for rectifying an AC input voltage into a rectified voltage; 1 a conversion A converter that converts the rectified voltage into an output AC voltage; a flat circuit connected between the full-wave rectifier circuit and the converter, including at least two capacitors and three diodes, making one of the two capacitors a capacitor When the cross voltage is lower than the rectified voltage, the two capacitors are subjected to a charging process in series. When one of the two capacitors has a cross voltage higher than the rectified voltage, the two capacitors are subjected to a discharge process in parallel. A voltage signal generator is connected between the flat circuit and the converter to provide a voltage signal. A controller is connected between the voltage signal generator and the converter and outputs a voltage signal according to the voltage signal. Switching signals to the converter; and an LC oscillating circuit including an oscillating inductor and an oscillating capacitor, the oscillating circuit is connected to the converter and a display Between the light tubes, when the rectified voltage increases, the converter increases one of the oscillating frequency of the output AC voltage according to the switching signal, so that the current flowing through the oscillating inductance is suppressed, and when the rectified voltage decreases The converter reduces the oscillating frequency according to the switching signal, so that the decrease of the current flowing through the oscillating inductance is reduced. _ 2 · If the electronic ballast with crest factor correction for a fluorescent lamp is the first in the scope of patent application, the above-mentioned full-wave rectifier circuit is a bridge type Page 20 200427374 6. Scope of patent application Rectifier circuit. For the items used in the 1X device to determine the Amway style, please call Shen Ruzheng • School 3 only one of the factors due to the peak wave fixture tube light fluorescent bridge straight half of the device for the device conversion Submitted to item 3 of the instrument. The enclosing body Fan An Jingli-type electric special sub-effect, please ask the electric field to apply the same two. • The school includes 4 light fluorescent current straight bridge and half of the above description. The first device encircles Fan An. The electric circuit of the special-type road please ask the resistor Shen Zhidian such as the positive connection 5 · The tube light of the number of factors in the school string and the fluorescent lamp for the system to produce lgb # The term of the signal piezoelectric is used, and the 5th device is set. For Amway-type students, please call Shen Zhiru 6 for the correction of the peak wave, the tube light, the fluorescent light, and the two resistors containing the package resistor. The resistance should be high through the transmitter. Come up in the upward direction, the frequency of the device will be settled, and the frequency will be settled. The circuit of the common benefit of a special student, please apply for the circuit. Ding Fan Amway-style students, please call Shen Zhiru 8 for the number of peaks due to the tube light and fluorescent lamp 1 For the items that should be used near the control of the transmitter Page 21 200427374 6. Scope of patent application The resonance frequency of the oscillating circuit starts the fluorescent tube. 9. For the electronic ballast with crest factor correction for a fluorescent tube as described in the first item of the scope of patent application, the above mentioned range of switching signal considerations ranges from 50,000 Hz to 80,000 Hz. 10. The electronic ballast with crest factor correction for a fluorescent tube as described in item 1 of the scope of the patent application, wherein the above-mentioned voltage signal rises when the rectified voltage increases, and when the rectified voltage decreases reduce. 11. An electronic stability controller comprising: a full-wave rectifier circuit for rectifying an AC input voltage into a rectified voltage; a converter for converting the rectified voltage into an output AC voltage; a power factor correction circuit for connecting Between the full-wave rectifier circuit and the converter, to improve the power factor of the full-wave rectifier circuit; a voltage signal generator connected between the power factor correction circuit and the converter to provide a voltage signal -., Flying:-a controller connected between the voltage signal generator and the converter, and outputting a switching signal to the converter according to the voltage signal; and an LC oscillating circuit including an oscillating inductor and An oscillating capacitor, the oscillating circuit is connected between the converter and a fluorescent tube, wherein when the rectified voltage increases, the converter increases an oscillating frequency of the output AC voltage according to the switching signal, so that the current flows through Current of this oscillating inductor Page 22 200427374 6. The scope of patent application is suppressed, and when the rectified voltage is reduced, the converter reduces the oscillating frequency according to the switching signal, so that the reduction of the current flowing through the oscillating inductance is reduced. 12. The electronic stability controller according to item 11 of the patent application range, wherein the full-wave rectifier circuit is a bridge rectifier circuit. Fan Li, please apply The straight bridge half is for the system replacement. The current of the transformer is the same as that of the straight type Φ—the bridge half described above. Items of fixed body Anjing type electronic effect electric field include 2 3 1 y The first bracket is Fan Fanli to transfer to the special stream, please submit to the middle section AP & Li Zhuan, please refer to Zhongru to produce igu for the system # 压 压 5 电 11 Description In the middle of the road, the circuit of the device is set in series, and it is recommended that the middle circuit block the electric circuit of the device in the series, including the resistance of the two included package resistors. Fan Li specially requested Shen Ruyi to pass through the transmitter, the process 17 control is described above, the device is set to the type of sub-electricity, the heat is advanced, and the frequency is oscillated. Item 1X I < No. Fan Li, please apply for such as 8 1X Page 23 200427374 6. Scope of patent application The controller starts the fluorescent tube by approaching the resonance frequency of the LC oscillator circuit. 19. For the electronic ballast with the scope of patent application No. 11, the above mentioned range of signal switching concerns is from 50,000 Hz to 80,000 Hz. 20. The electronic ballast according to item 11 of the patent application scope, wherein the voltage signal mentioned above increases when the rectified voltage increases, and decreases when the rectified voltage decreases.