TW444516B - Single-switch dimmable electronic ballast with high power factor - Google Patents

Abstract

This invention is about a kind of new single-switch dimmable electronic ballast with high power factor, in which single-switch energy-recycling converter is used. Only one active switch is used to have power factor correction, high frequency lighting up and dimming functions. The voltage tolerance required for the switch used is lower and dimming control method is simple such that it is easy to design protective circuit. As compared with the other electronic ballast having high power factor, the proposed single-switch circuit can save the cost of electronic ballast.

Description

V. Description of the invention (u [Creative Background] Electronic ballasts use electronic switches to switch on high-frequency lighting. The overall light efficiency ratio (lumens per watt (LPW)) is higher than traditional ballasts. Electronic ballasts are small in size, light in weight, and do not flicker. Has gradually replaced traditional ballasts. Recently, European and American countries have imposed regulations on current harmonics generated by electronic devices, such as IEC1000-3-2. In order to comply with these standards, electronic ballasts must have a high power factor. In order to save energy, the demand for electronic ballasts with dimming function is gradually increasing. In order to meet the above requirements, general electronic ballasts use power factor correctors and dual crystal high-frequency inverter cascades , The minimum number of active switch crystal switches (active switch) is three. And the dual-crystal high-frequency converter requires an isolated circuit (isolatecj driver). In order to reduce the cost of the ballast, all the automatic circuits use automatic switches. Self-excited, and self-excited drive circuits are more difficult to achieve dimming. Recently, in order to adapt to the regulations of current harmonics, single-stage electronic ballasts can have both The function of power factor green positive and high frequency converter. This kind of single-stage electronic ballast uses less active crystals, there are two types of single crystals, of which the single crystal type has a lower cost. 纟 is a single crystal type It can do the work of power factor corrector and high-frequency converter at the same time; the problem power of the J device is 23 to 4 times 1. The active crystal withstand voltage is the maximum voltage of the power supply, and the high withstand voltage crystal The cost is high and the efficiency is low. 2. The waveform of the current f of the lamp tube has the phenomenon of non-existence.

4445 1 6 V. Description of the invention (2) 3. The dimming range is limited. Therefore, single crystal electronic ballasts are still rarely used. [Creation summary] In view of these two shortcomings, the present invention proposes a new single crystal electronic stabilizer. This ballast can meet power factor correction, high frequency converter and dimming functions. The used crystal withstand voltage is only twice the maximum voltage of the power supply, the output waveform is symmetrical, and the protection circuit is easy to design. The circuit diagram of the crystal electronic ballast is shown in the first figure. The AC power source 1 is rectified into DC power through a power source filter 2 (1 nef i 1 ter) and a rectifier 3. The function of the power factor correction inductor Lpf is to improve the power factor and directly inject electric energy into the single-switch energy-recycling converter 5 (single-switch energy-recycling converter). The role of fast diode Dpf is to prevent reverse current from occurring. The single-crystal energy cycle converter 5 ′ used in the single-crystal electronic ballast of the present invention uses a switching crystal s and a diode D, which are connected in series to two ends of two energy storage capacitors C1 and C2; two inductors L1 and L2 are energy cycling inductors, which form a charge and discharge effect on the two capacitors. In the first figure, the inductors L3, L1, and L2 are combined with each other to form a transformer τ. This transformer is used for electrical isolation. The resonance circuit includes an inductor Lr connected in series with the fluorescent tube, and a driving capacitor Cp connected to the fluorescent tube. The control circuit 6 detects the current through the switching crystal S and the voltage on the capacitor C2 to protect the over-voltage and over-current or short-circuit phenomenon from occurring. The current detection point in the center is A, and the voltage bias detection point is corrected. If an overvoltage, overcurrent, or short-circuit fault occurs, the control circuit 6 stops the control pulse at the control point G to achieve the purpose of protecting the ballast. No.- 圊 of single crystal energy cycle converter 5, its circuit extension spectrum

E: \ Lcs \ electronic stabilizer.ptd

Page 5 4 4451 6 V. The description of the invention (3) (topology) is the only form. In order to facilitate identification and interpretation, the circuit is drawn in the second figure. The two capacitors C1 and C2 function in the second figure are The amount of the current input of the switching crystal S is connected to the positive terminal of one of the storage capacitors C1, and the current output terminal of the switching crystal S is connected to the negative terminal of the other storage capacitor C2. The anode of diode D is connected to the negative terminal of C1, and the cathode is connected to the positive terminal of C2. The inductor L1 is connected to the negative terminals of the two energy storage capacitors, and the inductor L2 is connected to the two energy storage capacitors C1 and C2, and the positive terminals of the inductor L1 & L2 ^ are coupled together. Control the duty cycle of the switching crystal S, and design the energy cycle inductors L1 and L2 to be a certain ratio, so that the internal energy balance of the energy cycle converter 5 can be maintained, and the voltages of the two capacitors Cl, C2 can be maintained at a certain ratio. Because the two energy loop inductors L1 and L2 have square waves, they can be used to directly light or when the transformer outputs high-frequency AC light. The power factor correction inductor Lpf attached to the energy-cycle converter 5 will generate a discontinuous conduction mode current with the switching of the switching crystal, and the power factor wall will be achieved. The capacitors, inductors, diodes, and switching crystals used in this single-crystal energy cycle converter 5 can actually be used in series or in parallel. If multiple series or parallel connections occur, the circuit topology is the same. To install voltage, current detectors or other protection components on the energy cycle converter 5, these detectors or protection components must be removed to compare the similarities and differences in the form of the circuit topology. The switching crystal S can be any type of electronic switch, such as a bipolar junction transistor (BJT), a metal oxide semiconductor field effect transistor (MOSFET), and an insulating gate pair. Carrier wafer

E: \ lxs \ electronic ballast.ptd page 6 f 4445 1 6 V. Description of the invention (4) (insulated gate bipolar junction trans i stor, IGBT) and other transistors or attached power switches with control circuit 6 (TOP switch) or power integrated circuit (power 1C). The third figure is an example of a control circuit composed of a commercial integrated circuit UC3 8 44. This control circuit is merely an example for convenience of explanation, and is not the only form of the control circuit 6. Vcc of UC3844 is connected to DC auxiliary power source Vs, and output OUTPUT is connected to control signal point G. When the single-crystal energy cycle converter 5 is working normally, the control signal point G sends a pulse frequency control switch Jing Zhao S of a fixed frequency and a fixed duty cycle to be turned on or open to make the energy cycle of the energy cycle converter 5 cycle, such as the fourth circle The TN region (t0 ~ tl) is shown. When it is necessary to adjust the brightness of the fluorescent tube, the duty cycle or frequency of the control signal can be adjusted, or both can be adjusted to achieve the purpose. "Point B is the voltage detection point, through the resistor R3 and ^ voltage division and compensation network R2 is connected in parallel with C5 to form a voltage feedback. Limit the voltage at point b to a certain value. ”In addition to overvoltage protection, the withstand voltage of the switching crystal S is also reduced, and the set point B is usually the maximum value of the power supply voltage, and the design inductor [I and L2 make the voltages of C1 and C2 equal; Then the withstand voltage of the switching crystal S is twice the maximum value of the power supply voltage. Point A is the current detection point. After r 1 and C4 paint waves, in addition to forming a current feedback, it also has an over-current protection function. VR1 and C6 generate an oscillation frequency. When the brightness of the light tube κ is to be adjusted, the dimmer 13 changes the oscillation frequency by changing the VR1 resistance value, and then the control signal point ^ pulse wave frequency is changed, so that the operating frequency of the single crystal energy cycle converter 5 is changed. By using the principle that the resonance circuit reacts differently at different frequencies, the FL current of the fluorescent tube is changed ', and the brightness of the fluorescent tube FL is also changed' as shown in the fourth figure (tl ~ t2). If the over-voltage phenomenon occurs at point B during the modulation, the voltage feedback causes

E _, \ Lcs \ Electronic ballast.ptd Page 74445 1 6 V. Description of the invention (5) The duty cycle of the control signal point G pulse wave is changed, as shown in the fourth area (TV area (t2 ~ t3)) to reduce Switching crystal S withstand voltage and increase dimming range_ Purpose. If overcurrent protection occurs during the modulation, the control signal point G pulse wave will be in a stop state, such as the TP area of the fourth frame (t3 ~ t4), and it will return to normal after the overcurrent phenomenon disappears (t4 ~ t5). If the lamp tube and the power source do not need to be electrically isolated, the resonance circuit connected to the lamp tube can be directly connected to the early-crystal energy cycle converter 5. The fifth figure shows the position of the lamp circuit 15 which can be connected to the single-crystal energy cycle converter 5. The lamp circuit 5 includes a fluorescent lamp FL, a resonance inductor Lr, and a starting capacitor Cp; in practice, to ensure long-term operation of the fluorescent lamp FL, the capacitor CB is often connected in the lamp circuit 15 'if the fluorescent lamp π The long-term operation makes the fluorescent tube FL not dim and other problems. Then the capacitor CB can be omitted. In order to reduce the cost, when driving the single-lamp lamp or the lamps are connected in series as a single circuit, the four inductors L1, L2, L3 and Lr can be combined into one transformer. [Explanation of the diagram] The first diagram is a circuit diagram of a single crystal high power factor dimmable electronic ballast. The second figure is a single crystal energy cycle converter. The third figure is an example of a control circuit. The fourth line is the waveform diagram of the control signal point G pulse wave and the output current of the fluorescent tube. The fifth figure is the position where the lamp circuit can be connected without electrical isolation. [Detailed description of the diagram] The first circuit of the single-crystal shangkung tunable electronic ballast: 1 ........ The input AC power can be single-phase or multi-phase power. 2 ........ Power-side filter to filter high-frequency noise.

4445 1 6 V. Description of the invention (6) 3 ........ Rectifier, bridge rectifier or other device that can rectify AC power. 4 ........ The transformer T is coupled by multiple inductors to provide electrical isolation. 5 ........ Single crystal energy cycle converter. 6 ........ Control circuit for controlling and protecting the ballast. Lpf ...... Positive inductance of power factor bridge. Dpf ... reverse prevention diode. S ........ switching crystal. D ........ Diode "Cl, C2 ·· _ · Energy storage capacitor. Rs ...... current detection resistor. L1, L2, L3 inductors can be coupled to each other to form a transformer. Lr ...... Resonant inductance, there can be multiple resonant inductances when multi-tube lighting, or it can be wound around transformer T with L1, L2, L3. FL ...... fluorescent tube, any luminous lamp body, multiple fluorescent tubes can be connected in series and parallel "Cp ...... Capacitors for starting fluorescent tubes can be used when multi-tube lighting Multiple. A ........ Current detection point. B ........ Voltage detection point. G ........ Control signal point. The second picture is a single crystal energy cycle converter. The first picture 5: S ........ switching crystal. D ........ diodes. Cl, C2 · * ·· Energy storage capacitor.

E ALcs \ Electronic ballast.ptd Page 9 4445 1 6 V. Description of the invention (7)

L1, L2 ·· '* inductors' can dissipate with each other to form a transformer. The third figure is an example of control circuit, No. 6-g. 1 3 ...... dimmer, hand or other device can adjust VR1.

Vs ... DC auxiliary power supply, supplying DC power to IC UC3844. UC3844 ··-Integrated circuit for control.

Vcc ’OUTPUT, VREF’ RT / CT ’GND, VFB, I SENSE, and COMP are the UC3844 pin names. A ........ Current detection point B ........ Voltage detection point G ........ Control signal point R1, C4 · · · · Current detection filter element . R3, R4 ···· Voltage detection resistor. C5, R2 _ ··· Voltage detection compensation circuit. C6 ... oscillation capacitor. VR1 ... variable oscillation resistance, or other components that can change the oscillation frequency. The fourth figure is the waveform of the control signal point G pulse wave and the output current of the fluorescent tube: The waveform diagram when the ballast of the TN area works normally. TD area (tb t2) ·, .. Waveform diagram when the ballast is dimmed. TV area (t2 ~ t3) ... Waveform diagram when the ballast is dimming and voltage feedback. TP area (t3 ~ t4), ··· Waveform diagram when ballast overcurrent protection. TN area (t4 ~ t5) • * .. Waveform when the ballast returns to normal. Fifth picture: the position where the lamp circuit can be connected without electrical isolation: 15 ...... lamp circuit.

E: \ Lcs \ electronic stabilizer.ptd page 10 4445 1 6 V. Description of the invention (8)

Lr ...... Resonant inductance, there can be multiple resonant inductances when lighting multiple tubes. FL ...... fluorescent tube, any luminous body, multiple fluorescent tubes can be connected in series and parallel. Cp ...... Enable the capacitor for fluorescent tube, there can be multiple when multi-tube lighting. CB ... series capacitor. S ........ switching crystal. D ........ diodes.

Cl, C2 · * + * energy storage capacitor. L1, L2 ... inductors can be coupled to each other to form a transformer.

E: \ Lcs \ Electronic ballast.ptd Page 11

Claims (1)

Correction mm 4445 1 6 Case No. 8811] 826 6. Application for patent scope 1. An electronic ballast of a light-emitting lamp includes a single crystal energy converter, a shielded transformer, a resonant inductor and a lamp resonance. Circuit composition; ballast uses only one active switching crystal and has power factor correction, high frequency lighting and dimming functions. 2. The fluorescent lamp electronic ballast described in item 1 of the scope of patent application, wherein the single crystal energy cycle converter includes: a switching crystal, a diode, two energy storage capacitors and two inductors ; The current input terminal of the switching crystal is connected to the positive terminal of the first storage capacitor, the current output terminal of the switching crystal is connected to the negative terminal of the second storage capacitor; the anode of the diode is connected to the negative terminal of the first storage capacitor The cathode is connected to the positive end of the second energy storage capacitor; the two ends of the first inductor are across the negative ends of the two energy storage capacitors, and the two ends of the second inductor are across the two positive ends of the energy storage capacitor. 3. The fluorescent lamp electronic ballast described in item 1 of the scope of the patent application, wherein a power factor correction inductor is added between the current output terminal of the switching crystal and the input terminal and the rectifier of the AC input terminal for power factor correction. . 4. The electronic ballast for fluorescent lamps described in item 1 of the scope of patent application, in which the power factor bridge positive inductance, if a reverse current occurs, a diode must be connected in series to prevent the reverse current. 5. The fluorescent lamp electronic ballast described in item 1 of the scope of patent application, wherein the two inductors of the single crystal energy cycle converter can be coupled to each other to form a transformer. 6. The electronic ballast for fluorescent lamps as described in item 1 of the scope of the patent application, wherein the lamp resonance circuit is placed in five places: the first is the current input terminal of the switching crystal of the single crystal energy cycle converter and Between outputs; second Page 12 2001.01. 12. 008 44451 Case 1 88111826 ^ The scope of the patent application is the two ends of the diode of the single crystal energy cycle converter; the third and fourth places are the two inductors of the single crystal energy cycle converter; the fifth place is The two inductors of the single crystal energy cycle converter are combined to form a transformer, and the lamp resonance circuit is connected to the secondary side of the transformer. 7. An electronic ballast for a fluorescent lamp as described in item 1 of the scope of the patent application, wherein the resonance inductance of the lamp resonance circuit can be coupled to a transformer of a single crystal energy cycle converter. Page 13 2001.01. 12. 009