Abstract: Introduced based on the autoexcitation type half bridge driver IR2135 fluorescent lamp electron ballast electric circuit, introduced emphatically filament preheating and unit electric circuit’s and so on start protection constitutions and the characteristic, and has given the detailed electricity schematic diagram.
Key word: Electronic ballast; Power factor adjustment; Filament preheating; Restarts moves
Introduction
Fluorescent lamp’s luminous efficiency surpasses the incandescent lamp already the fact which becomes does not struggle, for this reason, in the recent 20 years, the electronic ballast around the world obtained the rapid popularization and the development, was half and half the conductor factory to promote numerous has used in the electronic ballast the driving circuit, the electronic ballast which this article introduced the IR2153 driver which and the Motorola Corporation’s MC33262 power factor controller developed based on IR Corporation, was one kind of structure is simple, the cost was inexpensive, reliability high solution.
1 autoexcitation type half bridge driver IR2153 introduction
IR2153 is advanced version VMOS which and the IGBT electronics grid driver promotes in IR2155 and in the IR2151 foundation, it is similar the high-pressured half bridge driver and to 555 time base circuit’s front end oscillator integration on a 8 foot chip, causes it to become a section of function to be more, changes actuates the IC chip in the use power. As shown in Figure 1, foot CT has at the same time the protection shutdown function, may use a low voltage signal to cause the driver to stop the output. Moreover, output pulse’s width maintains equal, once Vcc rises to the undervoltage block system threshold value, the driver can start the starting of oscillation by a stabler frequency. Through reduces electronics grid driver di/dt the peak value and enhances the undervoltage block system threshold value the lag voltage to arrive at 1V, enabled electric circuit’s anti-chirp nature to have the substantive enhancement, simultaneously, the electric circuit pin’s whole anti-chirp protection aspect also had the improvement.
Figure 1
2 power factor compensating circuit
MC33262 belongs to the active power factor adjuster, is suitable specially in the electronic ballast and in the off-line type switching power supply makes the pre-switch to use, as shown in Figure 2, its interior integrated many control functions: In order to be advantageous for this electric circuit’s independent employment to be equipped with starts the timer; In order to realize approaches has used the first quadrant multiplier in 1 power factor; Zero electric current examination can the guarantee circuit work in the critical breakover way; The fast starting circuit improved electric circuit’s start characteristic; Is also equipped with the preparatory school the reference potential source, the transconductance error amplifier and the electric current examination comparator; The totem pole output structure is suitable to use in the driver power MOS tube. In addition, the MC33262 interior also integrated many protection functions, if has pressed the comparator to be able to reduce the out of control output voltage which the idling causes; The multiplier output inlays the position to limit the biggest peak value switch electric current; The actuation output top digit inlays the position, has realized to the MOS tube plate protection extremely; Also has the input belt hysteresis characteristics undervoltage exclusive circuit, the continual current limiting characteristic and the RS lock saves for the single pulse survey and so on.
3 electric circuit principle of work
Electronic ballast detailed electricity schematic diagram as shown in Figure 3, may divide into parts and so on EMI filter, bridge-type rectification, power factor control, half bridge invertor, lamp resonance, start and protection circuit.
3.1 input the EMI filter circuit
Besides is composed of the F1A fuse and the RVP1 varistor the overflow overvoltage protection electric circuit, the electronic ballast’s input circuit is mainly the EMI filter. This is a typical two level of compound expression low-pass filtering electric circuit, the CP1~CP4 filter electric capacity uses in filtering the string mold unwanted signal, C1 and a C2 end meets the output separately, another end is earthing together continually as the center point, can suppress the syntype disturbance, LP1 and LP2 is the syntype impedance coil effectively, uses in filtering the syntype disturbance, its two coils circle separately in the low loss, on the high magnetic conductivity ferrites magnetism link, when has the electric current winds through, in two coil’s magnetic fields mutually will strengthen, LP1 and LP2 inductance quantity and EMI filter’s nominal current related, filter’s resonance frequency must be lower than by farBallast operating frequency.
3.2 frequency conversion control circuit
We knew that the fluorescent lamp must pass through preheating, the ignition can enter the normal illumination active status. In these three conditions, the invertor is in the frequency conversion working, first, compares the high frequency to carry on to the filament preheating, enables the negative pole to achieve the launch electron the temperature; Then, the frequency drops fast, when arrives at the series resonance frequency, produces the resonant high pressure causes the tube instantaneous puncture ignition; Finally, stabilizes in the operating frequency. The IR2153 oscilation frequency may (1) decide by the type that the series resonance frequency (2) decided by the type.
Through changes IR2153 the external connection the CT available capacity to be possible to realize the frequency control, therefore, we may through NPN the triode QN1 breakover and the closure, cut the way which two vibration electric capacities connect, thus has realized the frequency control. Figure 3 after the circular telegram, fills the beforehand QN1 not breakover in capacitor CC14, electric capacity CC18 and the CC19 series has decided the oscilation frequency, when after capacitor CC14 fills, the DC18 breakover, the QN1 breakover, capacitor CC19 does not have an effect, the frequency decided by the capacitor CC18 direct earth.
3.3 preheating control circuits
After the circular telegram, before the DC18 breakover, QN1 does not cut off, IR2153 by the preheating frequency starting of oscillation, QN2 does not cut off, VCC provides the bias electric current after RC22 to the MO4 electronics grid to cause its breakover, CO33 and the LO6 starting of oscillation, the filament transformer work, preheating start; Afterward, when CC14 voltage magnification, after causing the DC18 breakover, the QN1 breakover, causes IR2153 at the normal work wobbulation, simultaneously, the electric current enables the QN2 breakover after RC21, the MO4 grid potential to arrive at zero, MO4 shuts off, preheating conclusion.
3.4 protection self-locking with restart the dynamic electricity road
The protection circuit the abnormal phenomenon which appears to the ballast use process in carries on the protection, generally uses the peak-to-peak value examination protection principle, this ballast protection function are many, altogether has 5 kind of protections, from RC36 introduction tube overvoltage protection; From RC37 introduction tube undervoltage protection; Protects 4 kinds from the DC19 introduction’s power source high pressure protection and from QP6 after the RC15 introduction’s power source low pressure, collected MOS to manage MC5 the electronics grid, when did not have the protection, the MC5 breakover, foot CT did not provide the differential pressure by the IR2153 interior, obtained the 8V voltage, the work is probably normal; When in 4 kind of protections has any kind occurs, MC5 breakover, OP7 as a result of base electrode electric potential earth, but the breakover, causes foot CT stepping down of voltage after RC33, the IR2153 stop vibration, half bridge electric circuit shuts off, by now, even if protection evacuation, because between MC5 and OP7 interlock, is also unable to restore foot CT the high electric potential, only then the power failure starts again, the ballast can resume the work.
Figure 3
Is different from the DC20 introduction’s filament protection with other 4 kind of protections, it has not protected the interlock function, therefore may start, when after the filament burns out or the tube is separated from, QN3, QN4, QN5 breakover, QN3 uses for to forbid to protect and the interlock electric circuit, QN4 receives foot CT, causes the IR2153 failure of oscillations, QN5 to cause the electric capacity CC14 electric discharge, to start prepares for, once the new tube installs, QN3, QN4, QN5 cuts off immediately, the startup procedure makes a fresh start preheating, the ignition and the steady work.
3.5 power source VCC electric circuit
In this ballast the IC power source’s design mainly from reduces the power loss to consider, when the electric circuit just started, manages DC4 and the DC5 voltage dropping first by the direct-current high pressure after the zener, by RC14 and the DC7 constant voltage power supply, as a result of the IR2153 micro power loss start characteristic, had guaranteed the electric circuit starts normally, when after IR2153 starting of oscillation, by clutches changing depressor LO4 secondarily after two group voltage doubling rectifications, as soon as goes via DC8 and RC23 supplies power to IR2153, another one goes via DPF2 and RPF4 for the MC33262 power factor controller power supply, when the electric circuit presents the protection, half bridge electric circuit stops the work, LO4 stops providing the voltage secondarily, the IR2153 power supply changes the micro power loss power supply. Obviously, after IR2153 failure of oscillations, MC33262 loses the electricity stop work, this to the power factor controller is also one kind of protection.
4 test results
Figure 4 is this ballast matches meets the tube voltage which and the filament current oscillogram OSRAM-FQ Gao Liang the T5 tube obtains, the power is 54W, uses the instrument for the distant place HB5A ballast comprehensive parameter reflectoscope reflector.
5 conclusions
The modern electron ballast is a knowledge breadth and the difficulty big technology, on the circuit wafer must input exchanges the 220V voltage, after passing through the full-wave rectification, outputs the 300V cocurrent high pressure, again after power factor adjuster pressure-rise stored energy inductance, then reaches as high as 400V, if in the design the primary device selects improper or in the debugging has slightly carelessly, will burn out the power tube, in this plan protection circuit’s design, reduced greatly presented the unusual burner tube’s opportunity. Moreover, restarts the electric circuit and the acceptor to this electric circuit in modifies slightly then uses in actuating the double tube, for this reason the author will write seperately to narrate.
