JPH06507777A - Power supply with high output coefficient along with control function to follow AC supply input - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Control function that follows AC supply input and Power supplies with both high output coefficients Industrial applicability The present invention relates to power supplies, particularly for driving gas discharge lamps such as fluorescent lamps. The present invention relates to the boost power supply used, but is not limited thereto.

Background technology Gas discharge lamps are nonlinear and have a negative load resistance, so they are driven by a stabilizing circuit. It is necessary to move. Such stabilization circuits are generally used for low frequency supplies (e.g. 60Hz It has a power source supplied by the main line (using the main line).

Such a stabilizing circuit ideally has a high power factor (output power and input power the ratio of the power obtained from the lamp to the power obtained from the main line. frequency) and low harmonic distortion characteristics (different frequencies from the mains frequency introduction) (harmonic distortion) be caught.

It is known that such stabilization circuits use a power supply, and t#j is, for example, Boosting the mains voltage by using a boost inductive element when starting the lamp . The current in the boost induction element is controlled by a pulse varying jill (PWM) signal. controlled by a switch (e.g. field effect transistor). Each PWM When the switch turns off at the end of the pulse, the induced current in the boost inductive element increases. generates a voltage.

The PWM signal typically occurs in a current mode control integrated circuit (IC).

Such current mode ICs are well known in the art.

Such power supplies detect the output voltage, induced current, and line current, and determine the output voltage of the circuit. Control the PWM signal (e.g. power factor) to improve the power factor. (through a multiplier). However, such existing devices are generally requires a specific IC to implement this additional control function.

Disclosure of invention One of the power sources provided by the invention includes an input receiving an alternating current supply voltage; an output that produces a voltage derived from said supply voltage; between said human power and said output; voltage generating means coupled to carry current and generate a voltage therefrom; said voltage generating means; switch means for controlling said current carried by the stage: and controlling the switching means to control the current carried by the voltage generating means; Control signal generating means for generating a pulse control signal to control the resulting voltage ; the power source comprises: the input and the control signal generating means; a modulator coupled between the alternating current supply voltage and modulating the frequency of the control signal by the alternating current supply voltage; voltage generating means for generating an electric current carried by said voltage generating means and for generating an alternating current. The magnitude of the alternating supply voltage is at a maximum such that it has a waveform that approximates the supply voltage. when the frequency of the control signal has a maximum value; It is.

In this way, an alternating supply voltage is used to vary the current carried by the voltage generating means. By doing so, we realize a voltage generation means that follows the AC supply voltage and applies a load The power supply will have low harmonic distortion and a high power coefficient.

One of the power sources provided by the present invention is also a power source that converts AC voltage to DC voltage. a full wave rectifier coupled to the AC voltage and a pulse width modulated signal source; means for generating a signal, said means having a control input, and said means generating said signal. the power source is controlled by a voltage source to generate the DCt pressure; producing a frequency of the pulse width modulation signal that varies depending on the magnitude of the AC voltage; means for coupling said control input to said full wave rectifier to the frequency of the pulse width modulation signal has a maximum value when the magnitude of the pressure is maximum; , resulting in a power supply consisting of a means to obtain a high output coefficient and low harmonic distortion. Ru.

Brief description of the drawing An example circuit for driving a fluorescent lamp and using a power supply according to the present invention is disclosed below. .

FIG. 1 shows a block schematic diagram of a fluorescent lamp drive circuit.

FIG. 2 shows the waveform of the supply line voltage applied to the circuit.

FIG. 3 shows the waveform of the line current derived by the circuit.

FIG. 4 shows the line current waveform derived by a circuit not using the invention.

The best form for carrying out inventions In FIG. 1, a circuit 100 driving three fluorescent lamps 102, 104, 106 is two circuits receiving between them an AC supply voltage of approximately 277 cm at a frequency of 60 Hz. It has input terminals 108 and 110. The full-wave rectifier bridge circuits 112 each have It has two input nodes 114, 116 connected to input terminals 108, 110t, and 2 It has five output nodes 118 and 120. Output node 11 of the buri noji 112 g+± O cored inductive element (cor) coupled to reference voltage rail (rail) 122 ed 1 inductor) 124 (has an inductance of approximately 4.5 mH) has one end that couples to the output node of bridge 112 and one end that couples to node 126. and the other end.

A field effect transistor (FET) 128 (of the BUZ90 type) is connected to node 126. It has a drain electrode to which it is coupled. Field effect transistor (FET) 128 is a resistor. Coupled to reference voltage rail 122 via resistor 130 (having a value of approximately 1.60) It has a source electrode.

Diode 132 (of the MUR160 type) has an anode coupled to node 126. , and a cathode coupled to output terminal 134.

Reference voltage rail 122 couples to output terminal 136. Integrating capacitor 137 is Coupled between output terminals 134 and 136.

A resistor 138 (having a resistance of approximately 2 MΩ) is connected to the output node 12 of the bridge 112. 0 and node 140. Capacitor 142 (approximately 0.0039μF ) is coupled between node 140 and reference voltage rail 122 . Current mode control integrated circuit (IC) 144 (ASTECSem1conduc tor, it is possible to use the AS3845 type) is connected to the node 140 has an RTICT input (bin 4). The current mode control IC 144 is a resistor 146 (having a resistance of approximately 10 Ω) to node 140 and a capacitor. connected to the base voltage rail 122 through a capacitor 148 (having a capacitance of approximately 0.22 μF). ■,. output (bin 8). Current mode control IC+44 is resistor 1 50 (having a resistance value of approximately 200) to the gate electrode of FET12g. control signal output (bin 6). The gate electrode of FET12g is connected to resistor 1. 52 (having a resistance of approximately 22 Ω) to the reference voltage rail 122. do.

Two resistors 154 and 156 (approximately 974 and 5.36 Ω resistors, respectively) (having a resistance value) is an intermediate node between the output terminal 134 and the reference voltage rail 122. connected in series via 15g. The current mode control IC 144 has a resistor 160 VF8 input (with a resistance value of approximately 47 Ω) is coupled to node 15g via Bin 2). Current mode control IC +44 is connected in series with resistor +6 2 (having a resistance value of approximately ICl0kΩ) and a capacitor 164 (approximately Q, I ■ Large input bin 2) Control IC 144 is connected to a capacitor with a capacitance of μF 166 (with a capacitance of about 470 pF) to the group r! Connect to At pressure rail It has a current sensing input (bin 3) whose current sensing input is connected to a resistor 168 (approximately 1 to Ω). (having a resistive value) to the source electrode of FET 128.

The current mode control IC 144 is connected to a resistor 170 (having a resistance value of approximately 240 Ω). has a cc input (bin 7) coupled to the bridge rectifier output node 120 via Its bridge rectifier output node has a capacitor 172 (with a capacitance of about 100 μF) to the reference voltage rail +22. Current mode control IC +44 is a reference voltage It has a GND input (bin 5) that couples to pressure rail 122.

The power supply output terminals 134 and 136 are connected to half-bridge inverters (haIf-brid ge1nverter) 174, whose output is coupled to a series resonant tank circuit ( series resonant + ank circuit) 176 It will be done. The output of the tank circuit consists of three fluorophores connected in series via converter 178. Combine with lamp. Configuration and operation of stabilization subcircuit elements 174, 176, 178 are well known in the art and will not be referred to further herein. do not have. Such sub-circuit elements are described, for example, in U.S. Patent Application No. 07/636.833. The US Patent Application No. , the content disclosed therein is also used in the present invention.

When the circuit in Figure 1 is in operation, 277V and 60Hz are applied to input terminals 108 and 110. voltage is applied, and the bridge +12 connects node 120 and reference voltage rail 122. Provides a unipolar, full-wave rectified, DC voltage with a frequency of 120Hz between . When FET 128 is enabled to conduct, this unipolar DC voltage The whole is connected to the inductive element 124, causing a current to flow through the inductive element. FET When 128 is disabled from conducting, this induced current develops in the inductive element. Increase voltage. This increased voltage is passed through the diode 132 to the output terminal 13. Sarel applied to 4. The increased voltage across output terminals 134, 136 is applied to inverter 17 4, charging the capacitor 137 that powers the series resonant tank circuit 176 and converter! 78 drives three series coupled fluorescent lamps 102.104.106. make it move.

Switching between enable and disable of FETI 2g is done by current mode. It is controlled by the control signal (output from bin 6) of the code control IC 144. IC The control signal output of is in the form of a pulse-radiation modulated signal whose mark interval During (m　a　rk　1nterva+), the FET switches to ON and conducts current. let

FET is OFF during space interval (space 1ninterval) switches to interrupt current conduction. At bin 6 of the IC, the pulse-radiation modulation signal is , nominal mark/space ratio (nomina1mark/5pace ratio ) is 1 and has a nominal 50% duty cycle. IC pulse width modulation The frequency of the controlled control signal and the voltage at node 120 are derived from the supply line. Determine the current.

In circuit 100, the nominal frequency of the PWM control signal is at bin 6 of IC 144. generated and determined by the product of the values of resistor 146 and capacitor 142, approximately 23k It is Hz.

However, current mode control IC 144 is connected to bridge 112 through resistor 138. When a 120Hz unipolar waveform output is applied to the input at bin 4, the IC's bin The frequency of the pulse width modulated control signal generated at input terminal 6 is determined at input terminal 108.1. changes in response to an AC line voltage (the waveform of which is shown in Figure 2) applied between be forced to do something. As the instantaneous value of the unipolar bridge output voltage increases As a result, the current applied to bin 4 of IC 144 increases and the PW at bin 6 of IC 144 increases. Increase the frequency of the M control signal output. Therefore, its bridge output voltage is zero The frequency of the PWM control signal output in bin 6 of the IC has a minimum value which is the value of The wave number has a nominal minimum value of about 23 kHz. The bridge output voltage is When having a peak value, the frequency of the PWM control signal output in bin 6 of the IC is approximately It has a maximum value of 43kHz. When the bridge output voltage is at an intermediate value, the The wave number of the PWM control signal decreases proportionally.

The frequency of the pulse modulated control signal generated at bin 6 of IC 144 is: Determining the current drawn from the bridge 112, i.e. from the AC supply line. Ru. Thus, depending on the voltage supplied, the line current (its waveform is shown in Figure 3) By varying , the line current becomes sinusoidal, with a power factor of about 1 and a low contributes to the circuit 100 along with high frequency distortion.

As mentioned above, line current flows across resistor 138 between node 120 and node 140. of the rectifying bridge 112 is forced to change due to the coupling provided through the rectifying bridge 112. Modulate the signal from the output and determine the frequency in bin 4 of IC144 manually RT/C given to a.

If resistor 131i is removed, the PWM output produced at bin 6 of IC 144 The frequency of the force signal is maintained constant at approximately 23 kHz and is derived by the current The line current will be as shown in FIG.

As can be easily understood by comparing the waveforms in Figures 3 and 4, the waveform in Figure 4 is similar to that in Figure 3. The waveform is also noticeably distorted from the sine wave, and near the zero crossing of the waveform shown at 180 This is particularly noticeable.

The distortion from the sine wave in these Figure 4 waveforms is increased total harmonic distortion (THD). :total harmonic distortion) and reduced output The coefficients are clearly shown, and both of them are implemented in the circuit 100 whose line current waveform is shown in FIG. Qualitatively avoided.

The calculated and measured values of the output coefficient and THD characteristics for the waveform in Figure 4 are approximately 0.95 and 15%. Output coefficient and THD characteristics by circuit 100 The calculated and measured values of are approximately 099 and 5%, respectively.

The modulation depth provided by the PWM output signal of 1C 144 changes the value of resistor 138. It is possible to change the node 140 and the base i1! of By inserting a resistor in parallel with the capacitor 142 between the voltage rail and the (not shown). Such changes are described above. larger or smaller for the non-sinusoidal region 180 shown in FIG. A lick is used to give compensation for cutting.

The present invention is used in a stabilizing circuit that uses a boost induction element to drive a fluorescent lamp. Although the description has been made with respect to a power supply, the present invention is based on the fact that THD and output coefficient depend on the characteristics of the power supply. It can also be used for other types of power supplies used within any product that is critical to be.

Various improvements and modifications to the embodiments described above may be made without departing from the inventive concept. It will be obvious to those skilled in the art. The concept is that depending on the applied supply voltage The concept of modulation is the concept of a control signal that determines the line current drawn by the power supply. , thereby reducing harmonic distortion and increasing the output coefficient.

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Claims (10)

[Claims] 1. an input receiving an alternating supply voltage; an output that produces a voltage derived from said supply voltage; between said input and said output; voltage generating means coupled to carry current and generate a voltage therefrom; said voltage generating means; switch means for controlling said current carried by the stage; and controlling the switching means to control the current carried by the voltage generating means; Control signal generating means for generating a pulse control signal to control the resulting voltage ; the power source comprises: the input and the control signal generating means; a modulator coupled between the alternating current supply voltage and modulating the frequency of the control signal by the alternating current supply voltage; voltage generating means for generating an electric current carried by said voltage generating means and for generating an alternating current. The magnitude of the alternating supply voltage is at a maximum such that it has a waveform that approximates the supply voltage. when the frequency of the control signal is comprised of modulation means having a maximum value; A power supply featuring: 2. 2. The voltage generating means according to claim 1, wherein the voltage generating means is comprised of an inductive element. power supply. 3. The switching means is characterized in that it is constituted by a field effect transistor. The power supply according to claim 1 or 2. 4. 2. The method of claim 1, wherein the control signal is a pulse width modulation signal. is the power supply described in 3. 5. The control signal generating means is comprised of a current mode control integrated circuit. A power source according to any one of claims 1 to 4. 6. The modulating means includes an impedance coupled between the input and the control signal generating means. 6. The power source according to claim 1, wherein the power source is comprised of a -dance. 7. A power supply for converting an AC voltage to a DC voltage, the power supply being connected to the AC voltage. a full-wave rectifier for generating a pulse-width modulated signal; and means for generating a pulse-width modulated signal; a control input, and said means are controlled by said signal to generate said DC voltage. , the power supply is: producing a frequency of the pulse width modulation signal that varies depending on the magnitude of the AC voltage; means for coupling said control input to said full wave rectifier to the frequency of the pulse width modulation signal has a maximum value when the magnitude of the pressure is maximum; , resulting in a high power coefficient and low harmonic distortion. and the power supply. 8. The means for generating the pulse width modulated signal receives power from the full wave rectifier. 8. The power source according to claim 7. 9. The means for generating the DC signal is comprised of a voltage booster circuit. 9. The power source according to claim 7 or 8. 10. Incorporating any of the power sources according to claims 1 to 9 for driving a gas discharge lamp. stabilizer circuit.