JP3480303B2 - Power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device that outputs a low frequency rectangular wave while suppressing a harmonic of an input current by using a commercial AC power supply as an input.

[0002]

2. Description of the Related Art FIG. 10 is a circuit diagram of a conventional power supply device. In this power supply device, a series circuit of switching elements Q1 and Q2, a series circuit of switching elements Q3 and Q4, and a series circuit of diodes D5 and D6 are connected in parallel between both ends of an electrolytic capacitor C1. . Connection points of switching elements Q1 and Q2 and switching elements Q3 and Q
The series circuit of the inductor L2 and the load circuit Z is connected between the connection point of No. 4 and the connection point of the diodes D5, D6 and the connection points of the switching elements Q1, Q2. The series circuit of L1 is connected. The switching elements Q1 to Q4 are provided with antiparallel diodes D1 to D4, respectively.

First, an example of the operation of this circuit is shown below. When the connection point side of the diodes D5 and D6 of the input AC power supply AC has a positive polarity, as shown in FIG. 11A, the switching elements Q2 and Q3 are ON, and the switching element Q is ON.
A period in which 1 and Q4 are OFF (see FIG. 12A), a period in which the switching elements Q1 and Q3 are ON and the switching elements Q2 and Q4 are OFF (see FIG. 12B),
The period when all switching elements are off (Fig. 12
(See (c)) in order, and it operates to repeat them periodically.

Further, a diode D of the input AC power supply AC
When the connection point side of 5 and D6 has a negative polarity, as shown in FIG. 11B, a period in which the switching elements Q1 and Q4 are ON and the switching elements Q2 and Q3 are OFF (FIG. 13).
(See (a)) and the switching elements Q2 and Q4 are O
N, a period in which the switching elements Q1 and Q3 are OFF (see FIG. 13B), and all the switching elements are OF
There are F periods (see FIG. 13C) in order, and the operation is performed to repeat them periodically. As the circuit operates as described above, the input commercial frequency power supply AC is applied to the load Z.
A rectangular wave voltage synchronized with is applied.

The switching element Q which is also used
Since the currents of the two loops flow in opposite directions at the same time in 1 and Q2, the current flowing through the switching element is substantially reduced, the loss of the switching element is reduced, the heat generation is suppressed, and the size is small. A low cost power supply device is provided.

[0006]

Regarding the case where a discharge lamp lighting device of a low frequency rectangular wave lighting system for lighting a high-intensity discharge lamp (hereinafter referred to as "HID lamp") is constructed by the above power supply device consider. Generally, the HID lamp is in a state of extremely high impedance (hereinafter, referred to as “no-load state”) until the discharge is started. To start the discharge, in the no-load state, the high voltage pulse voltage is superimposed on the voltage applied to the lamp to start the discharge. Immediately after the start of discharge, the temperature inside the tube is low, so the pressure inside the tube is low, and the state of low impedance (that is, low lamp voltage state) is maintained.By maintaining the discharge state, the temperature inside the tube rises and the pressure inside the tube also increases. Then, the electrical impedance also rises, and a stable lighting state is entered. As described above, in order to stably start and light the HID lamp, 200V to 400V is applied when the high voltage pulse is applied.
It is necessary to create a state in which a certain voltage is applied. Also, H
For the ID lamp, it is necessary to equivalently connect capacitors in parallel in order to stabilize the discharge and bypass the high frequency component of the current so that the high frequency current does not flow to the discharge lamp. This is because no acoustic resonance phenomenon occurs.

In the conventional example, the operation at the time of starting when the above HID lamp is used as a load is not taken into consideration. It is also necessary to control the power supply voltage, the voltage applied to the lamp in the unloaded state, and the voltage stored in the smoothing capacitor C1 in an optimum relationship. For example, when a voltage of 300 V is applied to the lamp in a no-load state, if the power supply voltage is AC200 V, the voltage of the smoothing capacitor C1 may be 400 V or higher due to the boosting action, but the smoothing capacitor is kept as much as possible while maintaining the no-load voltage of 300 V. It is better to operate so as to lower the voltage of 1), and the conventional example does not consider means for optimally adjusting the relationship of these voltages.

The present invention has been made in view of the above circumstances, and an object of the present invention is to supply a commercial AC power supply as an input and to output a low frequency rectangular wave while suppressing harmonics of an input current. In order to provide a control means of a no-load secondary voltage when using an HID lamp as a load.

[0009]

The main circuit configuration of the power supply device of the present invention is equivalent to that of the conventional example of FIG. However,
As a load Z of 0, a parallel circuit of a lamp load LD and a capacitor C2 is connected. C1 is a smoothing capacitor. The operation of each of the switching elements Q1 to Q4 in the unloaded state is basically the same as that of the conventional example (FIGS. 11 to 1).
3). Each of the switching elements Q1 to Q4 is formed of a MOSFET and has a reverse diode built therein.

In the unloaded state, the voltage across the smoothing capacitor C1 is Vce, and the voltage across the load is Vo2.
The next voltage Vo2 can be considered to be constant. A current flows from the smoothing capacitor C1 to the load through the inductor L2 by the operation of each of the switching elements Q1 to Q4, but under the assumption that the no-load secondary voltage Vo2 is constant, the load is reduced during one switching cycle. The average value of the current flowing through the load must be 0 (if the average value of the current flowing through the load is not 0, the no-load secondary voltage Vo2 increases or decreases).

Explaining this with reference to FIG. 9, for example, the current flowing through the inductor L2 during the period of FIG.
ce-Vo2) / L2, and the peak value is reached in the period t1. Next, during the period of FIG. 9B, the peak value decreases with a slope of −Vo2 / L2, and during the period t2, the peak value has the opposite polarity and the same absolute value as the peak value. Figure 9
In the period of (c), it rises with a slope of (Vce-Vo2) / L2, and the current reaches 0 eventually. Therefore, the current flowing through the inductor L2 has positive and negative symmetries, and the average value is substantially zero.

When the periods shown in FIGS. 9A and 9B are represented by the duty ratio (duty), d1 = t1 / T and d2 = t2, respectively.
/ T. Since there is no power consumption in the load when there is no load, and the circuit loss is 0 if an ideal circuit is considered, the voltage Vce of the smoothing capacitor C1 does not change regardless of the circuit operation, so d2 = 0 (( However, since the current actually flows in the circuit, the voltage Vce of the smoothing capacitor C1 tries to decrease, and therefore d2> 0, and the power that compensates for the circuit loss is AC power. Works as supplied from AC.

It can be said that the characteristic is that the current of the inductor L2 once reaches 0 at a point just half the duty d2 from the current of the inductor L2 at the time of no load shown in FIG. 9 (d). Therefore, when this is expressed by an equation, (Vce−Vo2) × d1 = Vo2 × d2 / 2, and this is solved for Vo2 to obtain Vo2 = Vce / (d2 / 2d1 + 1).

The present invention is a no load 2 as expressed by the above equation.
It focuses on the relationship between the secondary voltage Vo2, the voltage Vce of the smoothing capacitor C, and the duties d2, d1, and makes it possible to arbitrarily adjust the relationship between the voltage Vce of the smoothing capacitor C and the no-load secondary voltage Vo2. Is. Hereinafter, description will be made with reference to examples.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIGS. 1 and 2 show the circuit configuration of Embodiment 1 of the present invention. The configuration of the main circuit shown in FIG. 1 is equivalent to that of the conventional example of FIG. With this power supply,
A series circuit of switching elements Q1 and Q2, a series circuit of switching elements Q3 and Q4, and diodes D5 and D6
Is connected in parallel between both ends of the electrolytic capacitor C1. A series circuit of a load circuit (a parallel circuit of the discharge lamp load LD and the capacitor C2) and an inductor L2 is connected between the connection point of the switching elements Q1 and Q2 and the connection point of the switching elements Q3 and Q4, and a diode is connected. D5, D6 connection point and switching elements Q1, Q2
A series circuit of an AC power supply AC and an inductor L1 is connected between the connection point of the AC power supply AC and the inductor L1. In addition, each switching element Q
1 to Q4 are composed of MOSFETs, and each incorporates an antiparallel diode.

A polarity detector 1 for detecting the polarity of the power source is connected to both ends of the commercial AC power source AC. A load voltage detector 2 that detects the absolute value of the load voltage Vo2 is connected to both ends of the capacitor C2. Each switching element Q1, Q2, Q3, Q4 has a drive circuit drv1,
Drive signals are input from drv2, drv3, and drv4. Each drive circuit drv1, drv2, drv3, d
For rv4, d1 supplied from the control circuit shown in FIG.
The timing signals d2 and d12 are distributed and supplied by the signal distributor 3 according to the polarity of the AC power supply AC.

FIG. 2 shows the configuration of the control circuit of this embodiment. This control circuit includes a PWM controller 4 and an error amplifier E.
A, monostable multivibrator MM and OR circuit OR
have. First, the PWM controller 4 will be described. When the transistor Q5 is off, the capacitor C3
Is charged by the constant current source Io, and the voltage Vrmp of the capacitor C3 increases linearly as shown in FIG. When the voltage Vrmp of the capacitor C3 reaches a predetermined voltage Verr, the Schmitt trigger element S having a hysteresis characteristic.
The transistor Q5 is turned on by T. As a result, the capacitor C3 is rapidly discharged. By the above operation, the voltage Vrmp of the capacitor C3 becomes a sawtooth wave. The voltage Vrmp of the capacitor C3 and the predetermined voltage Verr
Are compared by a voltage comparator CP to generate a pulse train signal d1 having a variable pulse width. This signal d1 corresponds to Q in FIG.
2 and the drive signal of Q1 in FIG. 11B.

An error amplifier EA compares the detected value Vlad of the load voltage Vo2 output from the load voltage detector 2 with the target value Vref, and a predetermined voltage Ve corresponding to the difference.
generates rr. MM is a monostable multivibrator, which generates a high-level signal d2 for a certain period in response to the fall of the pulse train signal d1 described above. This signal d
2 is the drive signal of Q1 in FIG. 11A and the drive signal of Q2 in FIG. 11B. OR is a logical sum circuit and adds the signals d1 and d2 to generate a signal d12.
This signal d12 is the drive signal of Q3 in FIG.
It becomes the drive signal of Q4 of 1 (b).

As described above, in the first embodiment, the load voltage Vo2
Is deviated from a predetermined value, only the duty of the signal d1 is changed according to the error. According to the above formula, since the load voltage Vo2 increases as the duty of the signal d1 increases, the load voltage V2 increases.
It is possible to automatically adjust o2 to a desired value.

(Embodiment 2) FIG. 4 is a diagram for explaining the operation of Embodiment 2 of the present invention, in which the load voltage Vo in Embodiment 1 described above is used.
2 and the voltage Vce of the capacitor C1 Vo2 / Vc
e, that is, the relationship between the duty ratio d1 and d2 and the step-down ratio of the load voltage Vo2 to the voltage Vce of the capacitor C1. As is apparent from FIG. 4, the step-down ratio Vo2 / Vce is in the range A in which the duty d1 is 0 to 0.2.
Can be greatly changed. Therefore, if the operating point of the first embodiment is set so that the duty d1 operates near 0 to 0.2, the control range of the load voltage Vo2 can be increased.

(Embodiment 3) FIGS. 5 and 6 show a circuit configuration of Embodiment 3 of the present invention. The configuration of the main circuit shown in FIG.
This is the same as the first embodiment. In this embodiment, the load voltage Vo
Instead of the load voltage detector 2 that detects the absolute value of 2, a smoothed voltage detector 5 that detects the voltage across the capacitor C1 is connected. Detection voltage Vce by the smoothed voltage detector 5
The error amplifier EA2 converts d into a voltage Verr2 according to the difference from the target value Vref2, and the voltage Verr2 is supplied to the control circuit shown in FIG.

FIG. 6 shows the configuration of the control circuit of this embodiment. This control circuit has a PWM controller 4, a d2 signal generator 6 and an OR circuit OR. First, the operation of the d2 signal generator 6 will be described. Due to the fall of the signal d1 output from the PWM controller 4, the output Q of the flip-flop FF is High level and the output Q ′ is Lo.
At the w level, the transistor Q6 is turned off, so the capacitor C4 is charged by the constant current power source I1.
The voltage Vrmp2 increases linearly. Capacitor C
When the voltage Vrmp2 of No. 4 reaches a predetermined value, it is detected by the Schmitt trigger element ST2, and the flip-flop F
Since the reset input terminal R of F is set to High level for a moment, the flip-flop FF is reset and the output Q is L
Since the ow level and the output Q'become High level and the transistor Q6 is turned on, the capacitor C4 is rapidly discharged. As a result, a triangular wave voltage Vrmp2 that oscillates depending on the signal d1 is produced. This triangular wave voltage Vrmp
2 and the error voltage Verr2 are compared by the voltage comparator CP2,
The comparison output is input to the AND circuit AND together with the output Q of the flip-flop FF to generate a signal d2 as a logical product. When the voltage Vce of the smoothing capacitor C1 of the main circuit deviates from the target value Vref2, the error voltage Verr2 increases and the duty of the signal d2 changes greatly.

Although the error amplifier EA and the load voltage detector 2 are used in the first embodiment, the error amplifier EA2 is used in the present embodiment.
Output Verr2 is divided by resistors R3 and R4, and PWM modulation is performed by the PWM controller 4 as the error voltage Verr to determine the duty of the signal d1.

In this embodiment, the signal d1,
If the duty ratio of d2 is constant, the capacitor C
The voltage reduction ratio between the voltage Vce of No. 1 and the load voltage Vo2 is constant, and the voltage Vc of the capacitor C1 is
The load voltage Vo2 is also controlled by controlling the duty of the signal d2 so that e becomes a predetermined value and dependently controlling the duty of the signal d1 so that the duty ratio of the signals d1 and d2 becomes a predetermined value. It is possible to keep it constant.

That is, in this embodiment, the signals d1 and d
The voltage Vr that increases linearly in order to determine the period of 2
mp, voltage Vrmp2 and error voltage Ver which is a DC voltage
Since r and Verr2 are compared, the duty of the signal d1 is proportional to the error voltage Verr, and the duty of the signal d2 is proportional to the error voltage Verr2. Further, since the error voltage Verr is determined only by resistance-dividing the error voltage Verr2, the error voltage Verr is proportional to the error voltage Verr2. Therefore, as a result, the duty ratios of the signals d1 and d2 are in proportion to each other, and the duty ratio of d2 / d1 is always constant.

For example, when the voltage of the AC power supply AC fluctuates, the duty of the signal d2 changes so as to keep the voltage Vce of the capacitor C1 at a predetermined value, but at the same time, the duty of the signal d1 appropriately changes to d2 / As a result of maintaining the duty ratio of d1 at a predetermined value, the load voltage Vo2
Can be kept constant regardless of power fluctuations.

(Fourth Embodiment) FIG. 8 is a diagram for explaining the operation of the fourth embodiment of the present invention. The load voltage Vo in the above-described third embodiment is shown in FIG.
2 and the voltage Vce of the capacitor C1 Vo2 / Vc
e, that is, the relationship between the step-down ratio of the load voltage Vo2 with respect to the voltage Vce of the capacitor C1 and the duty ratio of d2 / d1. As is clear from FIG. 8, d2 /
In the range B in which the duty ratio of d1 is 0 to 4, the step-down ratio Vo2
/ Vce can be greatly changed. Therefore, in the fourth embodiment, in the circuit system of the third embodiment, the duty ratio of d2 / d1 is set to about 0 to 4. This makes it possible to widen the selection range of the step-down ratio.

[0028]

As described above, according to the present invention, the chopper circuit improves the input distortion from the AC power supply and the load circuit is provided with the inverter circuit for supplying the low frequency output synchronized with the AC power supply. In a power supply device having a configuration in which a switching circuit that performs the power conversion of the above-mentioned one uses a switching element in common, the driving period of the switching element is changed so that the output voltage becomes a predetermined value when there is no load. The currents of the two current loops flow in the opposite directions to reduce the loss, and the necessary voltage can be applied to the load when the load consumes almost no electric power and there is almost no load. Therefore, when the HID lamp is used as the load, good operation can be realized during steady lighting and no load.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a main circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a control circuit according to the first embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of the first embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the second embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a main circuit according to a third embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a control circuit according to a third embodiment of the present invention.

FIG. 7 is a waveform diagram for explaining the operation of the third embodiment of the present invention.

FIG. 8 is an operation explanatory diagram of the fourth embodiment of the present invention.

FIG. 9 is a waveform diagram showing a high-frequency change in the output current of the power supply device of the present invention.

FIG. 10 is a circuit diagram of a conventional example.

FIG. 11 is a waveform diagram of a drive signal of a switching element of a conventional example.

FIG. 12 is a circuit diagram showing a switching operation of a conventional example when the power source has a positive polarity.

FIG. 13 is a circuit diagram showing a switching operation of a conventional example when the power source has a negative polarity.

[Explanation of symbols]

Q1-Q4 switching elements D5, D6 diode C1 capacitor L1 First inductor L2 second inductor AC AC power supply DL discharge lamp load

Continuation of front page (56) Reference JP-A-4-163891 (JP, A) JP-A-4-58768 (JP, A) JP-A-3-60375 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H02M 7/5387 H02M 7/217

Claims (5)

(57) [Claims] 1. A first diode and a second diode , respectively.
A circuit in which the first and second switching elements provided in anti- parallel are connected in series so that the forward directions match, and the third and third
Third and fourth with four diodes in anti- parallel respectively
And a circuit in which the switching elements of are connected in series so that their forward directions match, and are connected in parallel with a capacitor with the same polarity,
With the same polarity as each diode with respect to the capacitor
5th and 6th diodes were connected in series so that
A circuit is connected in parallel with the capacitor, and a connection point of the first and second switching elements and a fifth and sixth diode are connected.
Between the connection point of the over-de, of the AC power supply and the first inductor is connected in series circuit, the connection point of the connection point of the first and second switching elements and the third and fourth switching elements during comprises a circuit arrangement with a series circuit of the load circuit and the second in-da Kuta, the first switching element and second switching element are shared by the step-down chopper circuit and the step-up chopper circuit, constant At the time of a load, the first and second switching elements, which have both the current for the step-up operation and the current for the step-down operation, are provided with a control circuit that operates so as to cause at least a period in which the currents cancel each other. is a power supply for applying an AC voltage synchronized with the input AC voltage, by the action of the control circuit, when the polarity of the connection point side fifth and sixth diode of the input AC power source is positive After the first operation period in which the second and third switching elements are turned on and the first and fourth switching elements are turned off, the first and third switching elements are turned on and the second and fourth switching elements are turned on. Turn off the element
A second operation period is provided, and thereafter, an operation of a switching cycle including at least a third operation period for turning off all the switching elements is performed, and the polarity of the connection point side of the fifth and sixth diodes of the input AC power supply is performed. Is negative, after turning on the first and fourth switching elements and turning off the second and third switching elements, the second and fourth switching elements are turned on after the fourth operation period. Turn off the 1st and 3rd switching elements
In a power supply device that performs a switching cycle including at least a sixth operation period in which all switching elements are turned off after a fifth operation period is provided, at least the fifth and sixth diodes of the input AC power supply are connected. A first operation period in which the second and third switching elements are turned on and the first and fourth switching elements are turned off when the polarity on the point side is positive, and the fifth and sixth input AC power supplies are operated. Turning on the first and fourth switching elements when the polarity of the diode connection point side is negative,
A power supply device, characterized in that a fourth operation period in which the second and third switching elements are turned off is changed so that the output voltage becomes a predetermined value when there is no load. 2. The step-down ratio as a ratio of the output voltage when there is no load and the voltage across the capacitor greatly changes in the first and fourth operation periods with respect to the change in the first and fourth operation periods. The area is set to an area.
The power supply described. 3. A fifth and sixth dio of an input AC power supply
First operation period and the ratio of the second operation period at the time the polarity of over de connection point side is positive, and, second of the input AC power supply 5
2. The ratio of the fourth operating period to the fifth operating period when the polarity of the connection point side of the sixth diode is negative is controlled so as to be constant when there is no load. Power supply. 4. A fifth and a sixth dio of an input AC power supply.
First operation period and the ratio of the second operation period at the time the polarity of over de connection point side is positive, and, second of the input AC power supply 5
And the ratio between the fourth operation period and the fifth operation period when the polarity of the connection point side of the sixth diode is negative, the output voltage under no load and the voltage across the capacitor are 4. The power supply device according to claim 3, wherein the power supply device is set in a region in which the step-down ratio as a ratio of 1 is significantly changed. 5. A fifth and sixth dio of an input AC power supply.
The first operation period in when the polarity is positive over de connection point side, and the fifth and fourth operating period at the time the polarity of the connection point side is a negative sixth diode of the input AC power supply,
5. The power supply device according to claim 4, wherein the power supply device is controlled according to a difference voltage between an output voltage and a constant voltage when there is no load or a difference voltage between a voltage across the capacitor and a constant voltage.