KR20090006920U - Electronic ballast for High Intensity Discharge lamp - Google Patents

Abstract

(A) Technical field

The present invention relates to an electronic ballast for a high-pressure discharge lamp.

(B) the problem to be solved;

The present invention is a technology that allows the DC-DC converter and the inverter to be performed simultaneously in the H bridge, the high-frequency switching of the high side in the H bridge by zero voltage switching to keep the lamp on.

(C) means for solving the problem;

In the present invention, when the high side is switched, it is vibrated by an inductor and a capacitor. At this time, a signal for frequency control is made, and it is inputted from a microprocessor, and the PWM output signal is increased and decreased to reach an internally set value. It is supplied to the frequency control terminal of the PWM generation IC to control the frequency so that switching can be made at the resonance point.

(D) effects, etc.

The present invention can reduce the number of parts economically constituting the ballast. In addition, the ballast according to the present invention can be miniaturized.

High voltage discharge lamp, electronic ballast, inverter driving method, metal halide lamp, xenon lamp

Description

Electronic ballast for high pressure discharge lamps {Electronic ballast for High Intensity Discharge lamp}

The present invention relates to an electronic ballast for high-pressure discharge lamps, and to maintain lighting at low frequency (1KHz or less) for driving high-pressure discharge lamp-type lamps such as metal halide lamps, xenon lamps, or ultra-high pressure mercury lamps with electronic ballasts. It relates to an electronic ballast which drives the ballast only.

Conventional technology of electronic ballast for high voltage discharge lamp receives commercial AC power and rectifies it to DC, then lowers the voltage by DC-DC (BUCK) converter and turns the high voltage discharge lamp by making the DC voltage thus formed into AC by H bridge. Keep it. The present invention eliminates the DC-DC converting circuit from the double, and directly applies the DC power supply to the H-bridge circuit and performs the form of combining the DC-DC converting circuit and the H-bridge at the H bridge all at once to maintain the high voltage discharge lamp on. It's about technology.

Conventional electronic ballast for high voltage discharge lamp rectifies AC to DC, and then lowers the voltage by DC-DC (BUCK) converter and makes the DC voltage thus formed to AC of low frequency by H bridge to keep lighting the high voltage discharge lamp. The present invention eliminates the double DC-DC converting circuit so that a DC-DC converter and an inverter are simultaneously formed in the H bridge. Each high side in the H bridge has a high frequency of several tens to several hundreds of kilohertz in a half cycle. The low side on the other side alternates switching to low frequency within 1Khz at the same time. At this time, the high side of the high side switching is switched to zero voltage to keep the lamp on.

Conventionally, in case of switching to low frequency only in H bridge, there is no practical problem even without zero voltage switching. However, in the case of high-frequency switching in high side, if the zero voltage switching is not performed, too much heat is generated and loss occurs. Many cannot be used. Therefore, when switching the high side, it is vibrated by the inductor and the capacitor. At this time, it creates a signal for frequency control and inputs it from the microprocessor to increase and decrease the PWM output signal to reach the internally set value. It is supplied to the frequency control terminal of the IC to control the frequency so that switching can be made at the resonance point.

The electronic ballast according to the present invention, compared to the conventional ballast, can eliminate the DC-DC converter circuit, thereby reducing the number of components and economically constructing the ballast. In addition, the conventional ballast is difficult to make the lamp and ballast integrated because the volume is large, but the ballast in the present can be miniaturized by reducing the number of component elements can be made into a lamp and ballast integrated. For example, a small high-voltage discharge lamp of 35W or less contributes to the popularization of HID by eliminating various inconveniences caused by separate ballasts by integrating and miniaturizing ballast lamp reflectors such as PAR38 lamps and compact fluorescent lamps.

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1

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 shows a circuit configuration of an electronic ballast for a discharge lamp according to the present invention. The ballast of the present invention is largely the power circuit unit 100, the inverter unit 200, the gate driver 300, the microcomputer control unit 400, frequency control signal detection unit 500, PWM control unit 600, auxiliary power supply 700 It is composed.

The power supply circuit unit 100 includes a filter for suppressing EMI therein and generates a direct current first voltage V1 from an AC voltage input by the rectifier circuit.

The inverter unit 200 includes the switching elements Q1 to Q4, the inductors L1 and L2, the capacitors C1 to C6, the current detector 210, and the high voltage generator 220. The DC first voltage V1 supplied by the power circuit unit 100 is connected to the drain terminals of the switching elements Q1 and Q3 and one terminal of the capacitors C1 and C3. The source of the switching element Q1, the drain of the switching element Q2 and one terminal of the capacitors C1 and C2 and one terminal of the inductor L1 are connected to the connection contact P1. The source of the switching element Q3, the drain of the switching element Q4 and one terminal of the capacitors C3 and C4 and one terminal of the inductor L2 are connected to the connection contact P2. One terminal of the inductors L1 and L3 and one terminal of the capacitor C5 are connected to the connection point P3. One terminal of the inductors L2 and L4 and one terminal of the capacitor C6 are connected to the connection point P4.

The current detector 210 includes a resistor R2 and a capacitor C8. The resistor R2 and the capacitor C8 are connected in parallel and are connected between the DC power minus GND and the DC detection voltage Vi.

The high voltage generator 220 includes inductors L3 and L4 and a capacitor C7. The inductors L3 and L4 are connected in series at both ends of the capacitor C7 and are connected between the connection points P3 and P4.

The circuit operation principle of the inverter unit 200 will be described with reference to FIGS. 1, 2, 3, 4, and 5. The switching elements Q1 to Q4 operate in pairs. During the period T1, the switching elements Q1 and Q4 operate in pairs, and during the period T2, the switching elements Q2 and Q3 operate in pairs. As shown in FIG. 4, the switching elements Q2 and Q4 switch at low frequencies of 1 KHz or less, and the switching elements Q1 and Q3 switch at high frequencies of tens to hundreds of KHz. Dead time exists between low frequency signals. First, when the switching elements Q1 and Q4 operate for the period T1, when the switching element Q4 is turned on at the low frequency, the switching element Q1 switches to the high frequency, which causes the switching element Q4 to The low frequency switching generates little heat, but the switching element Q1 performs high frequency switching and generates a lot of heat. Furthermore, full voltage switching generates a lot of heat. However, according to the present invention, even when the switching element Q1 performs high frequency switching, the inductor L1 and the capacitor C1 are switched at the point of resonance, thereby switching at zero voltage to suppress heat generation. Part waveforms are shown in FIG. 5 when the switching element Q1 switches. First, when the first DC voltage V1 is formed and the gate of the switching element Q1 is turned on, the connection point P1 is an exponential waveform up to the period Tf, like the waveforms of P1 and P2 over time from the zero voltage. The curve leads to the first DC voltage V1. At this time, the frequency control signal detection unit 500 detects the frequency control voltage Vf and sends it to the microcomputer control unit 400 to determine the signal and sends a signal to the PWM control unit 600 to control the frequency appropriately and to switch at the time Tf of FIG. 5. When the element Q1 is turned ON, there is almost no switching loss. The operation of the switching elements Q1 and Q4 in maintaining lighting is the same as that of the similar BUCK circuit and is shown in FIG. In detail, during the period T1, since the switching element Q2 includes a diode therein, the switching element Q2 may be represented as a flywheel diode in the BUCK circuit. Thus, the switching element Q1 switches at the point of resonance by the capacitor C1 and the inductor L1, and becomes the P1 and P2 waveforms when the resonance of FIG. 5 occurs, and is smoothed by the capacitor C5 to provide the DC first voltage. A direct current second voltage V2 lower than V1 is formed at the connection point P3 and supplied to the lamp. Even during the period T2 during which the switching elements Q2 and Q4 operate, the same operation is performed so that the direct current third voltage V3 is reversed from the direct current second voltage V2 so that the low frequency AC is applied to the lamp. Provide the voltage. Inductors L3 and L4 and capacitor C7 act to smooth by low frequencies.

When a current flows in the negative line of the circuit, the current detector 210 forms a voltage at the resistor R2, smoothes the capacitor C8, and supplies the current signal to the microcomputer controller 400 as a current signal.

The high voltage generator 220 operates the H bridge inverter at a high frequency at the initial stage of lighting to generate a high voltage of 1,000 volts or more by resonance of the inductors L3 and L4 and the capacitor C7 to start lighting the discharge lamp.

The gate driver 300 performs high side driving of the diodes D12-D16, the capacitors C22 and C23, the resistors R20-R38, the transistors TR12-TR15, the AND gates AND1-AND4, and the H bridge. IC (IC10, IC11) for.

The operation principle of the gate driver 300 will be described with reference to FIGS. 2 and 4. The gate driver 300 receives a low frequency waveform (Fl waveform) from the microcomputer controller 400 and a high frequency waveform (Fh1, Fh2 waveform) from the PWM controller 600. These waveforms are synthesized by the AND gate, and at the start of the lamp, high frequency waveforms are supplied to the H bridge, and after startup, the low frequency and high frequency waveforms are synthesized as waveforms in the respective parts of FIG. First, when the lighting starts, the terminal Fl of the microcomputer control unit 400 emits a low signal. Then, the transistor TR12 is turned off so that the connection point L1 becomes a high signal, and terminal 1 of the gate AND 1 and terminal 5 of the AND gate AND3 also become high. Then, the Fh1 waveform is supplied from the terminal Fh1 of the PWM control unit 600 to the terminal 2 of the gate AND 1 and the terminal 6 of the AND gate AND 3 so that the waveform of the high frequency is converted into the switching element Q1 of the H bridge. Switch Q4). Referring to the operation of the other pair of switching elements Q2 and Q3, the microcomputer control unit 400 sends a high signal through the terminal ON, which causes the transistor TR15 to be turned on, the transistor TR14 is turned off, and the direct current 12V is resistance. Via R34 and diode D14, the connection point L2 is in a high state. Thus, terminal 4 of the AND gate AND 2 and terminal 7 of the AND gate AND 4 are in a high state. The Fh2 waveform at the terminal Fh2 of the PWM controller 600 is supplied to the third terminal of the AND gate AND 2 and the eighth terminal of the AND gate AND 4 to supply the AND gates AND 2 and AND 4. The output terminal outputs the Fh2 waveform. This thus switches the switching elements Q2 and Q3. Thus, when the H bridge is switched at a high frequency, the high frequency generator 220 generates thousands of volts of voltage by resonance of the inductors L3 and L4 and the capacitor C7 to start the discharge lamp. Now, when the lighting is started, the voltage Vi is generated by the current detector 210 of FIG. 1, and the lamp is turned on by the microcomputer controller 400. The microcomputer control unit 400 that recognizes the lamp ON immediately outputs the low frequency Fl waveform of FIG. 4 to the terminal Fl, and the terminal ON emits a low signal. Based on this, the process of switching the parts of the H bridge will be described. This switching is performed in pairs. First, the switching devices Q1 and Q4 switch. As described above, the microcomputer control unit 400 outputs the Fl waveform to the terminal Fl, and the gate driver 300 receives the inputs thereof, and the transistors TR12 and TR13 are alternately turned on and off. As shown in FIG. 4, the low frequency L1 waveform is generated and supplied to terminal 1 of the AND gate AND 1, and the terminal 2 receives the Fh1 waveform to generate the Q1 gate waveform as shown in FIG. 4. This is supplied to the gate of the switching element Q1 through the IC IC10 for driving the high side gate of the H bridge. At the same time, when the input signal is input to the AND gate AND 3, the terminal 5 receives the L1 waveform, and the microcomputer control unit 400 outputs a low signal at the terminal ON with the start of lighting. OFF and DC 12V is supplied to input terminal 6 of AND gate AND3 through resistor R35 and diode D16. As a result, the L1 waveform is output from the output of the AND gate AND3. Therefore, this waveform is supplied to the gate of the switching element Q4. As a result of this, during the period T1, the second DC voltage V2 is supplied to the lamp at the connection point P3. Next, the switching elements Q2 and Q3 switch. As described above, during the period T2, the L2 waveform of the low frequency is generated at the connection point L2 as shown in FIG. 4. Since the terminal ON of the microcomputer control unit 400 outputs a low signal, the transistor TR15 is turned off. Then, the transistor TR14 is turned on through the resistors R35 and R37. Then, the connection point of the resistor R34 and the diode D15 becomes zero voltage, and the L2 waveform is input to the fourth terminal of the AND gate (AND 2), and the terminal 3 receives the Fh2 waveform, which is synthesized, and the Q3 gate is output to the output terminal. Generate a waveform. This is supplied to the gate of the switching element Q3 through the IC IC11 for driving the high side gate of the H bridge. At the same time, when the AND signal (AND 4) is input, the low frequency L2 waveform is input to the terminal 7 as described above, and the microcomputer control unit 400 outputs a low signal at the terminal ON with the start of lighting. Therefore, this causes the transistor TR15 to be turned off, and DC 12V is supplied to the input terminal 8 of the AND gate AND4 through the resistor R35 and the diode D15. As a result, the L2 waveform is output from the output of the AND gate AND4. This is supplied to the gate of the switching element Q4. As a result, at the connection point P4, the direct current third voltage V3 is reversed from the direct current second voltage V2 during the period T2 and supplied to the lamp to maintain lighting at a low frequency.

The microcomputer control unit 400 includes a microprocessor IC12, resistors R40-R46, and capacitors C24-C28.

The operation principle of the microcomputer control unit 400 will be described with reference to FIGS. 1, 2, and 5. The input signal of the microcomputer control unit 400 receives the current signal from the current detector 210 to the terminal Vi, divides the DC first voltage V1 into the resistors R1, R50, and R51 to the terminal Ve. Receives the input voltage signal. Then, the frequency control voltage is input to the terminal Vf for frequency control. The output signal outputs the low frequency Fl waveform of less than 1Khz to the terminal (Fl) after the start of lighting.The output terminal (ON) sends a high signal when the lamp is turned off and a low signal when the lamp is turned on. There is a terminal for outputting a PWM signal (Frequency / PWM), a terminal for output watt control (Power / PWM), and an output terminal (SHUT DOWN) for protecting a ballast such as starting failure or over watt. The microprocessor IC12 having such an input / output signal recognizes that the lamp is turned off when the voltage is below a certain level through the terminal Vi after the power is turned on, and outputs a high signal to the terminal ON, and the terminal Fl outputs a low signal. do. In addition, Frequency / PWM signal and Power / PWM signal are set to appropriate values for smooth start of lighting. When the lighting starts, the terminal ON outputs a low signal, and the terminal Fl outputs the Fl waveform of FIG. 4. As time elapses after the start of lighting, the PWM signal of the terminal Power / PWM is properly controlled to calculate the power by the product of the current signal Vi and the voltage signal Ve to reach a normal watt. The Power / PWM signal is smoothed to a DC voltage by the resistors R44-R46 and capacitors C26 and C27, and input to the terminal Pr for controlling the time of the PWM control unit 600 to perform watt control. The frequency control receives a voltage from the terminal Vf of the frequency control signal detector 500 and controls the frequency / PWM width of the microprocessor IC12 so that the voltage falls within a predetermined range, thereby controlling the resistors R40-R43 and the capacitor. (C24, C25) to smooth the frequency control of the PWM control unit 600 is connected to the terminal (Fr) to control the appropriate frequency so that the frequency is switched at the resonance point. This will be described in detail with reference to FIG. 5. For example, in the case of switching later than the resonance point, the oblique area becomes wider, thereby increasing the voltage of Vf. Conversely, if switching is done too fast, the area of the oblique line is reduced, resulting in a lower Vf voltage. At this time, the microcomputer controller 400 sets the voltage value Vf at the point of switching at the resonance point inside the processor, and if the voltage Vf from the frequency control signal detector 500 is too high, the microcomputer controller 400 switches later than the resonance point. When the PWM signal is changed to control the frequency in a fast direction and the diagonal area decreases, the Vf voltage is lowered. When the waveform of P1 is reached, the processor stops the frequency change and maintains the resonance state. On the contrary, if the Vf voltage is lowered by switching before the resonance point, the switching is faster than the resonance point. Therefore, the frequency / PWM signal is controlled until the frequency is delayed until the P1 waveform is reached. In this way, when the Vf voltage is within the proper range, the microprocessor stops the frequency change and reaches the resonance point, thereby enabling zero voltage switching.

The frequency control signal detector 500 includes resistors R10-R19, capacitors C20 and C21, diodes D10 and D11, and transistors TR10 and TR11. The resistors R10 and R11 are connected in series between the connection point P1 and the minus. The connection point P5 of the resistors R10 and R11 is connected to the collector of the transistor TR10 and the emitter is connected to the negative. And the connection point P5 is connected to the anode of the diode D10. The cathode of the diode D10 is connected to the resistor R12. The base of the transistor TR10 is connected to the terminal Fh1 of the PWM controller 600 via a resistor R14. The resistors R12, R13, and R15 connected to the connection point P7 connect the capacitor C20 with the minus, and the terminal Vf of the microcomputer control unit 400 connects the resistors R15, R16 and the capacitor C21. And the other terminal of resistor R16 capacitor C21 is negative. The resistors R18 and R19 are connected in series between the connection point P2 and the negative, the connection point P6 of the resistors R18 and R19 is connected to the collector of the transistor TR11 and the emitter is connected to the negative. And the connection point P6 is connected to the anode of the diode D11. The cathode of the diode D11 is connected to the connection point P7 via a resistor R13. The base of the transistor TR11 is connected to the terminal Fh2 of the PWM controller 600 via a resistor R17.

The operation principle of the frequency control signal detector 500 will be described with reference to FIGS. 1 and 5. During the period T1 during which the switching elements Q1 and Q4 operate when the lighting is turned on normally, for example, the connection point P1 resonates as shown in FIG. 5 by switching the switching element Q1 by the Q1 gate waveform. P1 waveform or late switching or fast switching. Since this and the in-phase gate waveform are generated at the terminal Fh1, when the transistor TR10 is switched with this waveform, in the case of resonance, it is divided by the resistors R10 and R11 at the connection point P5 to form the waveform of P5 in FIG. . The same principle applies to the switching of the switching elements Q2 and Q3 to form the waveforms of P2 and P6. P5 and P6 waveforms formed by half-waves of low frequency are rectified by diodes D10 and D11 and smoothed by resistors R12, R13 and R15 and capacitors C20 and C21 to control the frequency control voltage Vf to the microcomputer control unit 400. Supplied by.

The PWM controller 600 includes an IC IC13 for generating PWM, resistors R47-R52, capacitors C28 and C29, and a transistor TR16. The operation principle thereof is that a basic oscillation frequency is generated by the resistor R48 and the capacitor C28 and the frequency is controlled by the terminal Fr of the microcomputer control unit 400. In addition, the PWM width is controlled by the voltage of the terminal Pr, thereby achieving watt control. Thus, the Fh1 and Fh2 waveforms are generated at the terminals Fh1 and Fh2 so that the high frequency waveforms of tens to hundreds of Khz have alternate phases with 180 degrees as shown in FIG. 4. When the protection mode is generated in the microcomputer control unit 400, a high signal is generated through the terminal S / D to stop oscillation, thereby turning off the switching elements Q1 to Q4 to protect the ballast by stopping the operation of the ballast.

The auxiliary power supply 700 receives the DC first voltage V1 to generate DC 12V and supplies the DC power to the gate driver 300 and the PWM controller 600. Then, DC 5V is made and supplied to the power supply of the microcomputer control unit 400.

1 is a configuration diagram of an electronic ballast for a high-pressure discharge lamp

2 is a detailed circuit diagram of each part

3 is a pseudo DC-DC (BUCK) converter circuit in the inverter section

Figure 4 is a gate and ramp waveform diagram of each part

5 is a waveform resonant and a waveform slower than the resonance and the resonant waveform of the inverter unit

Claims (6)

A power supply circuit unit for outputting a voltage obtained by rectifying an EMI filter by inputting commercial AC; An inverter unit for switching the supplied direct current to high and low frequencies in response to gate driving signals to start and maintain lighting of a discharge lamp; A gate driver for outputting a gate signal for switching the switching element of the inverter unit to a high frequency and a low frequency; It receives the frequency control signal and outputs the signal for controlling the frequency to the PWM controller for zero voltage switching, the signal for controlling the watt, detects the lighting status, outputs the low frequency waveform, and outputs the protection signal in case of abnormal operation. A microcomputer control unit; A frequency signal control detection unit for detecting a frequency control signal from the inverter unit; A PWM controller for generating a high frequency waveform and controlling frequency and watts; An electronic ballast for a high-pressure discharge lamp, characterized in that the auxiliary power supply for supplying the operating power to the gate driver, microcomputer control unit, PWM control unit. The electronic ballast of claim 1, wherein the inverter unit includes an inverter circuit capable of generating a voltage of 1,000 volts or more by resonance due to a high frequency at start-up and generating an alternating current by a low frequency after lighting. 3. The zero voltage switching device of claim 2, wherein the inverter outputs a signal for frequency control from a microcomputer control unit which receives a frequency control signal from a frequency control signal detector and performs frequency control through a PWM controller to receive a gate driving signal through a gate driver. Electronic ballast for high-pressure discharge lamp, characterized in that. The electronic ballast of claim 1, wherein the gate driver has a circuit in which low and high frequencies are synthesized. The microcomputer control unit of claim 1 receives the frequency control signal from the frequency signal control detection unit so that the inverter unit switches to zero voltage so that the voltage reaches a value set therein. Electronic ballast for high-voltage discharge lamp, characterized in that the signal for controlling the frequency of the PWM control unit. The frequency signal control detection unit includes a circuit for receiving a signal from the connection point (P1, P2) of the inverter circuit, and outputs a voltage signal for the input voltage for controlling the frequency signal in the microcomputer control unit Electronic ballasts for high pressure discharge lamps.

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