KR20010089039A - Electronic ballast for high intensity discharge lamp - Google Patents

Abstract

PURPOSE: An electronic ballast for discharge lamp is provided to reduce a heat radiation by performing a soft switching through a resonance mode in a high frequency switching of a high part. CONSTITUTION: A power circuit unit(100) performs an EMI(electromagnetic interference) filtering of an inputted alternating current for common use, and outputs a rectified voltage. An inverter unit(200) switches the supplied direct current with high or low frequency to turn on a discharge lamp in response to a switching driving signal. A driving circuit unit(300) outputs a signal for switching a switching element of the inverter unit(200) with high or low frequency. A low frequency signal generation and protection circuit unit(400) supplies the driving circuit unit(300) with a low frequency signal and includes a protection circuit.

Description

Electronic ballast for discharge lamps {ELECTRONIC BALLAST FOR HIGH INTENSITY DISCHARGE LAMP}

The present invention relates to an electronic ballast applied to a high voltage discharge lamp such as a metal halide lamp, a high pressure mercury lamp, a sodium lamp, and an ultraviolet (UV) lamp. The low frequency square wave is superimposed on a high frequency switching waveform to be supplied to a discharge lamp to maintain lighting. . This is advantageous for the electronic ballast which eliminates the acoustic resonance caused by the metal halide lamp, especially in the high-pressure discharge lamp. To date, such a driving method is disclosed in US Pat. No. 5,428,268. In other words, a square wave DC power source that is switched at a high frequency by a DC-DC converter in advance in front of a full-bridge inverter driven at a low frequency is inverted at a low frequency to maintain a discharge lamp. This is because when the low-frequency and high-frequency switching at the same time directly in the full-bridge inverter is difficult to be practical because the heat generated by the switching element is severe due to full voltage switching, the present invention is a low-frequency and high-frequency switching by a single step in the full-bridge inverter At the same time, it provides an electronic ballast using soft switching technique by resonance of inductor and capacitor during high frequency switching. This method is simpler and cheaper than the method of switching to high frequency at the front end of the inverter.

In order to solve the problems of the prior art, the first object of the present invention is to rectify the input AC power into DC and perform the high frequency switching and the low frequency switching by a single step in the inverter. At this time, the switching of the HIGH part of the inverter is switched to a soft-switched waveform by the resonance of the inductor and the capacitor.As a result, a high-voltage discharge can suppress the generation of heat and noise even when switching by a single step in the inverter unit. It is to provide an isoelectronic ballast.

It is a second object of the present invention to provide an electronic ballast for a high-pressure discharge lamp having a driving circuit section for driving a switching element of a full bridge inverter.

It is a third object of the present invention to provide an electronic ballast for a high-pressure discharge lamp having low frequency generation for supplying a low frequency signal to a driving circuit portion.

It is a fourth object of the present invention to provide an electronic ballast for a high pressure discharge lamp for overcurrent protection, overheat protection of an inverter, and start failure protection for protecting a ballast from abnormal operation.

A fifth object of the present invention is to provide an electronic ballast for a high-pressure discharge lamp having a constant power control.

In order to achieve the above object, the device of the present invention filters the electromagnetic wave by inputting commercial AC and the power circuit unit for making a direct current, and the direct current power source made in the power circuit to perform high frequency switching and low frequency switching at the same time to light the discharge lamp with soft switched waveform And a low frequency generation and protection circuit portion for driving the drive circuit portion, and a drive circuit portion for driving the inverter portion.

1 is a circuit diagram of an electronic ballast for a discharge lamp according to the present invention.

2 is a preferred embodiment according to the present invention.

3 is a low frequency generation and protection circuit according to a preferred embodiment of the present invention.

4A is a soft switching principle diagram according to the present invention.

4B is a waveform diagram according to FIG. 4A.

Fig. 5 is a waveform diagram of each part of the inverter of the preferred embodiment.

<Description of the symbols for the main parts of the drawings>

100: power circuit unit 200: inverter unit

210: high pressure generating unit 220: current detecting unit

300: driving circuit unit 310: high frequency generation unit

320: inverter drive unit 400: low frequency generation and protection circuit unit

410: low frequency generating unit 415: low frequency generating unit

420: protection circuit

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 composed of the power circuit unit 100, the inverter unit 200 and the driving circuit unit 300, the low frequency generation and protection circuit unit 400.

The power supply circuit unit 100 includes a filter for suppressing EMI, a rectifying unit for converting AC into direct current, an auxiliary power transformer T3, and a direct current auxiliary power source.

The power circuit unit 100 rectifies the input AC power through a filter and outputs a DC first voltage V1. The input AC power is stepped down by the transformer T3 to generate a DC first auxiliary voltage, a DC second auxiliary voltage, and a DC third auxiliary voltage. The AC input power is supplied to the low frequency signal generation and protection circuit unit 400 for low frequency signal generation.

The inverter unit 200 includes switching elements Q1-Q4, diodes D1-D7, inductors T1, T2, resistors R1, capacitors C3, C4, C6, C8, and high voltage. It is composed of a generator 210 and a current detector 220. The DC first voltage V1 supplied by the power circuit unit 100 is connected to the first inductor primary first coil T1 / 1. The other terminal of this coil is connected to the connection terminal of the drain terminals of the switching elements Q1 and Q2 and the cathodes of the diodes D4 and D5. In order to suppress spikes during switching of the switching elements Q1 and Q2, a resistor R1 and a capacitor C3 connected in parallel are connected in series with the diode D2, and this is the first inductor primary coil T1. / 1) in parallel. In order to know whether the discharge lamp is lit or not, the induced voltage is rectified by the diode D3 in the secondary coil T1 / 3 of the first inductor, and smoothed by the capacitor C4 and output to the terminal 5. On the other hand, the source of the switching element Q1 includes the drain of the switching element Q3, the cathode of the diode D6, the anode of the diode C4, the anode of the diode D4, and the primary coil T2 / 1 of the second inductor. Is connected to one terminal. The source of the switching element Q2 is connected to the drain of the switching element Q4 and the cathode of the diode D7 and the anode and the lamp of the capacitor C8 and the diode D5. The source of the switching element Q3 and the anode of the diode D6 and the capacitor C6 and the source of the switching element Q4 and the anode of the diode D7 and the other terminal of the capacitor C8 are the current detector 220. Is connected to the connection point of the resistor R2 and the capacitor C5.

The circuit operation principle of the inverter unit 200 will be described with reference to FIGS. 4A, 4B, and 5. The switching elements Q1 to Q4 operate in pairs. The switching elements Q4 and Q1 operate in pairs, and the switching elements Q3 and Q2 operate in pairs. As shown in FIG. 5, the switching element Q4 switches at a low frequency of several tens of Hz to 1 KHz or less, and in the same period, the switching element Q1 switches at a high frequency of several tens of KHz. When the period T1 ends, the switching elements Q3 and Q2 operate symmetrically with the switching elements Q4 and Q1 in the next period T2. There is a dead time between the two low frequency signals. First, when the switching elements Q4 and Q1 operate for the switching time T1, the switching element Q1 switches to the high frequency when the switching element Q4 is turned on at the low frequency during the switching time T1. Due to this, the switching element Q4 generates little heat by low frequency switching, but the switching element Q1 performs high frequency switching, thereby generating a lot of heat. In addition, when full-voltage switching, a lot of heat is generated. However, in the present invention, even though the switching element Q1 performs the high frequency switching, the inductor T1 and the capacitor C6 generate resonance to switch at zero current to suppress heat generation. Part waveforms are shown in FIG. 4B when switching element Q1 switches. At this time, when the gate of the switching device Q1 is turned on at the terminal P1, switching is performed at zero current by resonance by the first inductor primary first coil T1 / 1 and the capacitor C6, and the switching device Q1 The waveform similar to the waveform V2 of FIG. 4B is generated by the counter electromotive force by the first inductor primary first coil T1 / 1 at the time of OFF. To suppress this, the voltage induced in the first inductor primary second coil T1 / 2 is refluxed by the diode D1, stored in the capacitor Cp, and used as an effective energy at the load side during the next switching. That is, at the moment when the counter electromotive force is generated by the first inductor primary first coil T1 / 1, a current is generated in the direction of the current i by the first inductor primary second coil T1 / 2, and thus the capacitor ( Accumulate energy in Cp). Diode D2, resistor R1 and capacitor C3 are inserted to suppress the spike voltage at the moment of switching. Even when the switching elements Q4 and Q1 are turned off and the switching elements Q2 and Q3 are operated, the same operation is performed as described above to perform zero current switching at the moment of switching, and soft switching by suppressing counter electromotive force.

The high voltage generator 210 includes a resistor R3-R5, a capacitor C7, a die solution D11, a thyristor QS1, an inductor and a transformer T2. This generates an impulse voltage for starting the start at the beginning of the high-voltage discharge lamp. A capacitor C7 and a resistor R5 are connected in series between the terminal P1 and the terminal P2, and the resistors R3 and R4 are connected between the connection point of the resistor R5 and the capacitor C7 and the terminal P1. Is connected in parallel, and similarly, the thyristor QS1 and the second inductor secondary coil T2 / 2 are connected in series. The die solution D11 is connected between the connection points of the resistors R3 and R4 and the gate of the thyristor QS1.

In the operation of the high voltage generator 210, when the switching elements Q1 to Q4 operate, charges are charged to the capacitor C6 through the resistor R5, and thus the voltage divided by the resistors R3 and R4 is reduced. The second inductor 2 is discharged when the charge charged in the capacitor C7 is discharged when a signal is transmitted to the gate of the thyristor QS1 at the moment when the threshold voltage of D11 is exceeded, and the thyristor QS1 is turned off when the discharge is completed. The counter electromotive force is generated in the secondary coil T2 / 2, and a high voltage is induced in the primary winding T2 / 1 of the second inductor by the primary and secondary winding ratios of the inductor T2 and applied to the discharge lamp.

The current detector 220 includes a resistor R2 and a capacitor C5. This converts the flowing current into a voltage by the resistor R2 and smoothes it by the capacitor C5 and inputs it to the feedback voltage of the high frequency generator 310.

The driving circuit unit 300 includes a high frequency generator 310 and an inverter drive unit 320. This provides a signal for switching the switching elements Q1-Q4 of the inverter unit 200. The waveform for this is shown in FIG. 5.

The inverter drive unit 320 includes optical signal separators ISO1 and ISO2, resistors R6 and R7, AND gates U2 / 1, U2 / 2, U2 / 3 and U2 / 4, and diodes (D9, D10) and the switching elements QT1 and QT2.The terminal 2 has an AND gate U2 / 3, an AND gate U2 / 4, an anode of the diode D9, and a base of the switching element QT1. The terminal 3 is connected to the AND gate U2 / 1, the AND gate U2 / 2, the anode of the diode D10, and the base of the switching element QT2. The PWM IC (U1) terminal 1 is connected to the other terminals of the AND gates U2 / 1-U2 / 4 The outputs of the AND gates U2 / 1 and U2 / 2 are optically connected through the resistor R6. And the outputs of the AND gates U2 / 3 and U2 / 4 are connected to the optical signal separator ISO2 via a resistor R7 Terminal 1 of the optical signal separator ISO1 is connected to the signal separator ISO1. ) Is connected to the positive pole of the DC secondary auxiliary power source and the terminal 3 is connected to the negative pole and the terminal P1. 2) is connected to the gate of the switching element Q1.The terminal 1 of the optical signal separator ISO2 is connected to the positive pole of the DC third auxiliary power source and the terminal 3 is connected to the negative pole and the terminal P2. The terminal 2 of the optical signal separator ISO2 is connected to the gate of the switching element Q2.

The inverter drive unit 320 receives the low frequency signals from the low frequency generator 410 to the terminals 2 and 3 and converts the low frequency signals into the switching elements QT1 and QT2 and the diodes D9 and D10 to switch the switching elements Q3 and Q4. Is supplied to the gate. Then, the high frequency signal is received from the terminal 1 of the PWM IC U1 and the high frequency signal and the low frequency signal input to the terminals 2 and 3 are synthesized by the AND gate U2 to receive the optical signal through the resistors R6 and R7. The signal is separated by the separators ISO1 and ISO2 and supplied to the switching elements Q1 and Q2. The waveform of each part is shown in FIG. 5.

The high frequency generator 310 is composed of a PWM IC U1, resistors R8-R17, a diode D8, and capacitors C9, C10. The terminal 2 of the IC U1 is connected to the positive electrode of the direct current first auxiliary power source and the negative electrode is connected to the terminal 8. A resistor R14 is connected between the positive electrode of the direct current first auxiliary power source and the terminal 1. The terminal 4 of the PWM IC U1 is connected in series with the resistor R10 and the resistor C9 at the connection point of the resistor R2 of the current detector 220 and the capacitor C5 in parallel with the resistor R10. It is connected to the terminal 4 and the terminal 5 of the PWM IC U1. In addition, resistors R8 and R13 are connected in series between the positive electrode and the negative electrode of the DC first auxiliary power source, and a connection point thereof is connected to the PWM IC U1 terminal 4 through the diode D8. A terminal connected in series with the resistor R11 and the capacitor C10 is inserted between the terminal 3 and the terminal 4 of the PWM IC U1 in parallel with the resistor R12. The resistors R15 and R17 are connected in series between the positive electrode and the negative electrode of the direct current first auxiliary power source and their connection points are connected to the PWM IC (U1) terminal 6. In addition, a resistor R16 is connected between the terminal 7 and the cathode.

The high frequency generator 310 generates a high frequency waveform of the PWM IC U1 of FIG. 5. The resistor R16 connected to the terminal 7 of the PWM IC U1 varies in frequency according to its magnitude, and the voltage divided by the resistors R15 and R17 is applied to the terminal 6. The minimum value of the ratio is determined. The generated high frequency waveform is output from the terminal 1 of the PWM IC U1 and becomes the input of the AND gates U2 / 1-U2 / 4 and outputs to the terminal 8. In the PWM IC U1 terminal 1, the current flowing when the discharge lamp is turned on is reduced to a voltage and inputted as a feedback voltage. The magnitude of the pulse width is determined according to the magnitude of this voltage, resulting in constant power control. The voltage divided by the resistors R8 and R9 is input to the terminal 4 through the diode D8 to have a maximum duty ratio. In addition, the terminal 3 serves to correct a signal input to the terminal 4. In addition, when excessive current flows through the inverter, a voltage higher than the normal voltage is input to the terminal 5 to stop the output signal to the terminal 1, and the output stops until the power is turned off and supplied again to protect the ballast.

The low frequency generation and protection circuit unit 400 includes a low frequency generation unit 410 and a protection circuit unit 420. Also shown here is a low frequency generator 415 of another embodiment. The circuit generates a frequency equal to an alternating current input by receiving a commercial exchange, such as the low frequency generator 410, or receives a high frequency signal from the high frequency generator 310, such as the low frequency generator 415 of another embodiment. The counter processes the signal to produce a low frequency signal. When the ballast fails to turn on even after a certain time elapses or becomes overheated, the protection circuit unit 420 stops the output to protect the ballast.

The low frequency generator 410 includes resistors R21 to R26, capacitors C21 and C22, switching elements QT7 and QT8, a buffer U6, and diodes D12 and D13.

The low frequency generator 410 receives an AC input signal through the terminals 6 and 7 and rectifies the half wave, and applies it to the base signals of the switching elements QT7 and QT8 to pass through the buffer to the terminals 2 and 3. Supply to the inverter driver 300 through.

The protection circuit unit 420 includes a binary counter U5, resistors R30-R36, NOR gates U3 / 3 and U3 / 4, a switching element QT6, diodes D15 and D16, It consists of a thyristor QS2, a capacitor C31, and a temperature switch T / S. The supplied commercial AC power supply is connected to the clock terminal CLK of the counter U5 by the series connection of the diode D13 and the resistor R30 through the terminal 7. A resistor R31 and a capacitor C31 are inserted between the clock terminal and the minus. The resistor R32 and the switching element QT6 are connected in series between the output terminal 12 and the minus of the counter U5, and the base of the switching element QT6 is connected to the terminal 5 through the resistor R33. . One input of the NOR gate U3 / 4 is connected to the connection point of the resistor R32 and the collector of the switching element QT6 and the resistors R35 and R36 are connected in series between the terminal 1 and the terminal 4. The temperature switch T / S is connected in parallel to the resistor R36, and a connection point of the resistors R35 and R36 and the temperature switch T / S is connected to the other terminal of the NOR gate U3 / 4. An output of the NOR gate U3 / 4 is an input of the NOR gate U3 / 3, and a resistor R34 is connected between the output of the NOR gate U3 / 3 and the gate of the thyristor QS2. The cathodes of diodes D15 and D16 are connected to the anodes of thyristor QS2. The diode D15 is connected to the connection point of the resistor R26 of the low frequency generator 410 and the collector of the switching element QT8, and the diode D16 is connected to the connection point of the collector of the resistor R22 and the switching element QT7, respectively. Connected.

The protection circuit unit 420 protects the ballast by shutting off the power when the discharge lamp is not turned on even after a predetermined time elapses or when it is overheated. The output terminal 12 of the counter U5, for example, in the case of a 14-bit binary counter, is switched to the HIGH signal when the clock signal is input 8192 cycles if the input is 60 Hz. This is about 2 minutes and 16 seconds. If the discharge lamp does not turn on until this time, the switching element QT6 is turned off. Therefore, a HIGH signal is inputted to the NOR gate U3 / 4 through the resistor R32 and the thyristor QS2 is turned on. The signal output of the output terminals 2, 3 of the low frequency generator 410 is stopped by turning ON. However, when the discharge lamp is driven, the base of the switching element QT6 is driven through the resistor R33 through the terminal 5 to bring the input signal of the NOR gate U3 / 4 to LOW to output normally.

The low frequency generator 415 of the embodiment different from the above includes the binary counter U8, the NOR gates U3 / 1 and U3 / 2, the AND gates U4 / 1-U4 / 3, and the resistors R40-R42. And a switching element QT5, a capacitor C41, and a diode D17. When the DC voltage of the DC first auxiliary power is supplied between the terminal 1 and the terminal 4, and the high frequency signal of the high frequency generator 310 supplied from the terminal 8 is input, the switching element QT5 receives the resistor R41. Is turned on, and the reset terminal RST of the counter U8 goes to the LOW state, thereby starting normal operation. If the counter U8 is 14 bits and the input frequency is 50 KHz, an output signal having a period of 1024 times than the input signal is generated through the terminal 10 of the counter U8. This is a frequency of about 97 Hz. When this signal is input to the AND gate U4 / 1, the signal delayed by the resistors R42 and C41 becomes the input of the NOR gate U3 / 2 and becomes the input of one terminal of the AND gate U4 / 2. The output signal of the counter U10 is input as it is to the other terminal of the AND gate U4 / 2. This process is inserted for dead time of valid signal section. The output of the AND gate U4 / 2 is output to the terminal 3 via the buffer U7 / 4-U7 / 6. On the other hand, the thrust of the terminal 10 of the counter U8 is input to the AND gate U4 / 3 via the NOR gate U3 / 1 and the other terminal is connected to the output of the NOR gate U3 / 2. This output is output to the terminal 2 via the buffers U7 / 1-U7 / 3. If the protection circuit unit is operated, the switching element RT5 is turned off, and the reset terminal RST and the NOR gate U3 / 1 of the counter U8 become HIGH to stop all output.

The effect of the present invention is as described in US Patent US 5,428,268 ballast for inverting at a low frequency by switching the direct current to a high frequency at the front end of the full bridge inverter to produce a switched high frequency DC power supply and supply it to the full bridge inverter In contrast, the present invention eliminates the step of switching the DC at the front end of the full bridge and simultaneously performs the switching of the high frequency and the low frequency directly at the full bridge inverter while reducing the heat generated by the soft switching by the resonance method during the high frequency switching of the high part circuit. Simplify and implement ballast at low cost.

A second effect of the present invention includes a driving circuit portion for driving a switching element of the inverter for low frequency switching the LOW portion of the inverter portion and providing a driving waveform for high frequency switching on the HIGH portion.

A third effect of the present invention is to provide a low frequency signal generation circuit for supplying a signal to the driving circuit portion.

A fourth effect of the present invention is to provide an electronic ballast for a high-pressure discharge lamp for overcurrent protection, overheat protection of the inverter, start failure protection for protecting the ballast from abnormal operation.

The final effect of the present invention is to provide an electronic ballast for a high-pressure discharge lamp that performs a constant power control in the high frequency generator.

Claims (10)

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 frequency and low frequency in response to switching drive signals to maintain a discharge lamp on; A driving circuit unit outputting a signal for switching the switching element of the inverter unit to a high frequency and a low frequency; An electronic ballast for a high voltage discharge lamp, characterized by comprising a low frequency signal generation and a protection circuit unit for supplying a low frequency signal to a driving circuit unit and including a protection circuit. The method of claim 1, wherein the inverter unit in the high frequency switching of the switching element of the HIGH portion of the inverter portion soft switching by resonance between the first inductor primary first coil and the sixth and eighth capacitors (C6, C8) of the LOW portion Electronic ballast for high-pressure discharge lamp, characterized in that. 2. The inverter of claim 1, wherein the DC first voltage of the power circuit unit is connected to the first inductor primary first coil T1 / 1, and the drain and diode of the switching elements Q1 and Q2 are connected to the other terminal of the coil. It is connected to the junction of the cathodes of D4 and D5, and the resistor R1 and the capacitor C3 connected in parallel are connected in series with the diode D2, and this is the first inductor primary first coil T1 /. 1) connected in parallel, the source of the switching element Q1 includes the drain of the switching element Q3 and the cathode of the diode D6 and the anode of the diode C4 and the anode of the diode D4 and 1 of the second inductor. It is connected to one terminal of the car coil T2 / 1, and the source of the switching element Q2 includes the drain of the switching element Q4 and the cathode of the diode D7 and the anode of the capacitor C8 and the diode D5. And a source of the switching element Q3 and the anode of the diode D6 and the source of the capacitor C6 and the switching element Q4. Anode and the other terminal of the capacitor (C8) of the diode (D7) is a high-pressure discharge lamp electronic ballast, characterized in that the circuit connected to the current detecting section 220. The 2. The inverter of claim 1, wherein a capacitor C7 and a resistor R5 are connected in series between the terminal P1 and the terminal P2, and a connection point between the resistor R5 and the capacitor C7 and the terminal P1. Is connected in series between the resistors R3 and R4, and the thyristor QS1 and the second inductor secondary coil T2 / 2 are connected in series to connect the resistor R5 and the capacitor C7. Is connected in parallel between the connection point of and the terminal P1, and the die solution D11 comprises a high voltage generating circuit connected between the connection point of the resistors R3 and R4 and the gate of the thyristor QS1. Electronic ballasts for high pressure discharge lamps. 2. The driving circuit according to claim 1, wherein the driving circuit part has a terminal (2) connected to an AND gate (U2 / 3), an AND gate (U2 / 4), an anode of the diode (D9), and a base of the switching element (QT1). (3) is connected to the AND gate (U2 / 1), AND gate (U2 / 2), the anode of the diode (D10) and the base of the switching element (QT2), and the PWM IC (U1) of the high frequency generator (310). Is connected to one terminal of the AND gates U2 / 1-U2 / 4, and the outputs of the AND gates U2 / 1 and U2 / 2 are connected to the optical signal separator ISO1 through the resistor R6. ), And the outputs of the AND gates U2 / 3 and U2 / 4 are connected to the optical signal separator ISO2 through a resistor R7, and the terminal 1 of the optical signal separator ISO1 is 2 is connected to the anode of the auxiliary power supply, terminal 3 is connected to the cathode and terminal P1, terminal 2 is connected to the gate of the switching element Q1, and terminal 1 of the optical signal separator ISO2 It is connected to the positive pole of the DC third auxiliary power source and the terminal 3 is connected to the negative pole and the terminal P2. And a terminal (2) connected to the inverter ballast connected to the gate of the switching element (Q2). 2. The driving circuit unit of claim 1, wherein the driving circuit portion of the PWM IC U1 is connected to the positive pole of the DC first auxiliary power supply, and the terminal 8 of the PWM IC U1 is connected to the negative pole. A resistor R14 is connected between the terminal 1 of the PWM IC U1 and a resistor R9 and a capacitor C9 between the PWM IC U1 terminal 4 and the terminal 5 and the current detector 220. ) Is connected in series with the resistor R10 in parallel, and the resistors R8 and R13 are connected in series between the positive electrode and the negative electrode of the DC first auxiliary power supply, and the connection point is connected to the diode D8. Connected to the PWM IC (U1) terminal 4 through the terminal 3 and the terminal 4 of the PWM IC (U1) connected in series with the resistor R11 and the capacitor C10 to the resistor R12. Inserted and connected in parallel, the resistors R15 and R17 are connected in series between the positive and negative poles of the DC first auxiliary power supply, the connection points thereof are connected to the PWM IC (U1) terminal 6, and the terminal 7 Resistance between minus and minus (R16) High-pressure discharge lamp electronic ballast characterized in that it comprises parts that are connected to the high frequency generation. 7. The driving circuit of claim 6, wherein the driving circuit unit includes a high frequency generator for detecting a load current and controlling a duty ratio of the high frequency generator 310 based on the load current to perform a constant power control and to stop generating a high frequency when a current above a reference value is detected. Electronic ballast for high-pressure discharge lamp, characterized in that. The low frequency generation and protection circuit of claim 1, wherein the terminal 6 is connected to the base of the switching element QT7 through a series connection of the diode D12 and the resistor R21, and the base of the switching element QT7. A resistor R23 and a capacitor C21 are connected in parallel between and, and terminal 1 is connected to the collector of the switching element QT7 through a resistor R22, and this connection point is connected to the buffer U6 / 1-U6. / 3) is connected to the output terminal (2), the terminal (7) is connected to the base of the switching element (QT8) through the series connection of the diode (D13) and the resistor (R24), A resistor R25 and a capacitor C22 are connected in parallel between the base and the minus, and the terminal 1 is connected to the collector of the switching element QT8 via a resistor R26, and this connection point is connected to the buffer U6 / 1-. Electronic ballast for high-voltage discharge lamp, characterized in that it comprises a low-frequency generating circuit connected to the output terminal (2) via U6 / 3). The low frequency generation and protection circuit of claim 1, wherein the terminal 7 is connected in series to the clock terminal CLK of the counter U5 by a series connection of a diode D13 and a resistor R30. The resistor R31 and the capacitor C31 are connected in parallel between the minus, the reset terminal RST is connected to the minus, and the resistor R32 and the switching between the output terminal 12 and the minus of the counter U5. The element QT6 is connected in series, the connection point of the resistor R32 and the collector of the switching element QT6 is connected to one input terminal of the NOR gate U3 / 4, and the base of the switching element QT6 is connected to the resistor R33. Is connected to the terminal (5) through the resistor (R35, R36) in series between the terminal (1) and the terminal (4), the connection point is input to the other terminal of the NOR gate (U3 / 4), The temperature switch T / S is connected in parallel to the resistor R36, the output of the NOR gate U3 / 4 is connected to the input of the NOR gate U3 / 3, and the output thereof is the resistor R34. Is connected to the gate of the thyristor (QS2) through the cathode of the diode (D15, D16) is connected to the anode of the thyristor (QS2) and the anode of the diode (D15) is the resistance of the low frequency generator 410 ( Electronic ballast for the high voltage discharge lamp, characterized in that it comprises a protective circuit portion connected to the connection point of R26) and the switching element QT8 and the anode of the diode D16 is connected to the connection point of the resistor R22 and the switching element QT7. . The electronic ballast of claim 1, wherein the low frequency generation and protection circuit unit comprises a low frequency generation unit which receives a high frequency signal and converts the high frequency signal into a frequency of about 10 to 1 KHz by a counter.