JP2003339159A - Power unit and hid lamp drive circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit which can realize high output of a chopper circuit by lessening resistance loss without being influenced by the ON-resistance of a switching element or the dispersion of the forward voltage of a diode. <P>SOLUTION: When pulses are outputted alternately from output terminals OUT1 and 2 of a controller CT, switching elements Q1 and Q2 of a step-down chopper circuit CH are turned on alternately, and currents IL1 and IL2, which flow alternately to reactors L1 and L2, rise gradually with a lapse of time interval t. When the power, calculated with a power arithmetic circuit M, reaches a specified value, the pulses from the output terminals OUT1 and 2 of the control circuit CT vanish, the switching elements Q1 and Q2 are turned off, and the currents IL1 and IL2 flowing to the reactors L1 and L2 drop with the lapse of the time interval t from their peak values. At this time, even if there is dispersion in the ON-resistance of the switching element or the forward voltage of the diode, the currents flowing in the switching elements become equal, which can remove the unbalance of the loss of the switching elements and the diode. <P>COPYRIGHT: (C)2004,JPO

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 for controlling a load connected to a chopper circuit.

[0002]

2. Description of the Related Art A power supply with smoothed alternating current is used as a power supply, and the output voltage of this power supply is converted into a predetermined voltage by a chopper circuit and supplied to a load. Control and constant voltage control may be performed. 7 is a circuit diagram showing an example of a power supply device using a step-down chopper circuit as a chopper circuit, and FIG. 8 is a diagram showing drive signals and current waveforms of the power supply device of FIG.

In FIG. 7, a step-down chopper circuit CH is provided between an input terminal I and an output terminal O, and a power calculation circuit M and a control circuit CT are connected to the step-down chopper circuit CH. The step-down chopper circuit CH is composed of a switching element Q, a reactor L, a diode D, and a capacitor C. ra and rb are step-down chopper circuits C
A voltage dividing resistor that divides the H output voltage Vo (terminal voltage of the output terminal), and rc is a resistor for detecting the output current Io of the step-down chopper circuit CH.

The power calculation circuit M includes a step-down chopper circuit C.
The voltage corresponding to the output current Io of H and the divided voltage of the output voltage Vo are input, and the output power P output from the output terminal O is calculated. The output power P output from the power calculation circuit M is input to the control circuit CT, and the control circuit CT
The on / off of the switching element Q is controlled so that the electric power of the output output from the output terminal O becomes constant.

As shown in FIG. 8A, when a drive pulse is output from the output terminal OUT of the control circuit CT and the switching element Q is turned on, a current IL flowing in the reactor L is generated.
As shown in FIG. 8 (b), gradually increases with the passage of time t. When the voltage corresponding to the output current Io of the step-down chopper circuit CH reaches a predetermined value corresponding to the electric power P calculated from the divided voltage of the output voltage Vo, the control circuit CT
No pulse is output from the output terminal OUT. Control circuit C
When the output of the output terminal OUT of T becomes low, the switching element Q is turned off and the current IL flowing in the reactor L.
Falls from the peak value with the lapse of time t. In this way, the control circuit CT controls ON / OFF of the switching element Q and appropriately selects the ON time of the switching element Q, so that the input voltage from the output side of the step-down chopper circuit CH becomes a predetermined voltage. A reduced output voltage is obtained, and for example, constant power is supplied to a load such as a lamp.

[0006]

In a power supply device using such a chopper circuit, in order to increase the output of the chopper circuit, conventionally, a plurality of switching elements and diodes have been connected in parallel. However, when a plurality of switching elements and diodes are connected in parallel, the on-resistance Ron of the switching element and the forward voltage V of the diode are increased.
Due to variations in F, the currents flowing through the respective switching elements were unbalanced. Since a large amount of current flows in HID lamps and the like, if such an imbalance occurs, there is a problem that the temperature is unbalanced or the current flowing in one of the elements becomes large and the element is destroyed. .

Therefore, it is necessary to balance such losses, and when a plurality of switching elements and diodes are connected in parallel, conventionally, as shown in FIG. 9, switching elements Q1, Q2 and a diode D1 are provided. , D2 are connected in series with resistors R1 to R4, respectively, to balance the loss. However, when the resistors are inserted in this way, the power loss in the resistor is large, the heat loss becomes a problem, and the efficiency becomes poor. At the same time, there is a problem that the temperature rises.

The present invention has been made in view of the above problems, and is not affected by variations in the ON resistance of a switching element or the forward voltage of a diode, and the power loss of the resistance is reduced to reduce the chopper. An object of the present invention is to provide a power supply device capable of increasing the output of a circuit.

[0009]

The present invention according to claim 1 is provided with a chopper circuit composed of a switching element, a diode, a reactor and a capacitor, and controls the switching element of the chopper circuit to be turned on and off to provide an output terminal. A power supply device for controlling a connected load is characterized in that a plurality of circuits each including a switching element, a diode, and a reactor are connected in parallel to a capacitor.

According to a second aspect of the present invention, in the power supply device according to the first aspect, the plurality of switching elements are alternately operated. According to a third aspect of the present invention, in the power supply device according to the first aspect, the chopper circuit is operated in a discontinuous type. further,
The invention according to claim 4 is an HID lamp drive circuit including the power supply device according to claim 3, wherein a chopper circuit of the power supply device is operated at a fixed frequency.

According to the present invention, a plurality of circuits each comprising a switching element, a diode and a reactor are connected in parallel with a capacitor, and even if there is a variation in the ON resistance of the switching element or the forward voltage of the diode, the current flowing through the switching element. Is determined by the value of the reactor, so if the inductors have the same inductance, the currents will be the same and the loss imbalance of the switching element and the diode can be eliminated.

Further, by alternately operating a plurality of switching elements, the ripple rate of the output current can be reduced, and by operating the chopper circuit in a discontinuous type, the influence of the through current of the switching elements can be eliminated. can do.
Furthermore, if the power supply device of the present invention is used in a HID lamp lighting circuit and the chopper circuit of the power supply device is discontinuously operated at a fixed frequency, the acoustic resonance phenomenon of the HID lamp is prevented, and the flickering of the lamp and the destruction of the lamp are prevented. Can be prevented.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing a power supply device according to an embodiment, and FIG. 2 is a diagram showing drive signals and output current waveforms of the power supply device of FIG.

In FIG. 1, I is an input terminal, O is an output terminal, Q1 and Q2 are switching elements, D1 and D2 are diodes, L1 and L2 are reactors, C1 is a capacitor,
Ra, rb, and rc are resistors, M is a power calculation circuit, and CT is a control circuit that controls on / off of the switching elements Q1 and Q2. MOSFETs, for example, are used as the switching elements Q1 and Q2.

An input terminal I is usually connected to a power supply that smoothes alternating current, and an output terminal O is connected to a load such as an HID lamp. The step-down chopper circuit CH includes switching elements Q1 and Q2, diodes D1 and D2, a reactor L1,
The switching elements Q1 and Q2, which are composed of L2 and a capacitor C1 and are connected in parallel to the input terminal I, are on / off controlled by outputs OUT1 and OUT2 of the control circuit CT. The resistors ra and rb are voltage dividing resistors that divide the output voltage Vo of the step-down chopper circuit CH, and rc is a resistor for detecting the output current ILo of the step-down chopper circuit CH. A voltage according to the output current ILo and a voltage proportional to the output voltage Vo are input to the power calculation circuit M, and the power P of the load connected to the output terminal O is calculated. The output power P output from the power calculation circuit M is input to the control circuit CT, and the control circuit C
T controls ON / OFF of the switching elements Q1 and Q2 so that the electric power of the load connected to the output terminal O becomes constant.

Next, the operation of the power supply device of FIG. 1 will be described with reference to the waveform diagram of FIG. When the power supply device is operated with the power supply connected to the input terminal I and the load connected to the output terminal O, the output terminal OUT1 or OUT of the control circuit CT is output.
The drive pulses are alternately output from 2. As shown in FIG. 2A, when a pulse is output from the output terminal OUT1 of the control device CT, the switching element Q1 is turned on, and the current IL1 flowing in the reactor L1 is the time as shown in FIG. 2B. It rises gradually with the passage of t. Then, when the power P calculated by the power calculation circuit M from the voltage corresponding to the output current Io of the step-down chopper circuit CH and the divided voltage of the output voltage Vo reaches a predetermined value, the output terminal O of the control circuit CT.
The pulse from UT1 disappears. When the output of the output terminal OUT1 of the control circuit CT becomes low, the switching element Q
1 is turned off, and the current IL1 flowing in the reactor L1
Falls from the peak value with time t.

Similarly, as shown in FIG. 2C, when a pulse is output from the output terminal OUT2 of the control device CT,
The switching element Q2 is turned on, and the current IL2 flowing in the reactor L2 gradually rises as time t passes, as shown in FIG. 2 (d). Then, when there is no pulse from the output terminal OUT2 of the control device CT, the switching element Q2 is turned off, and the current IL2 flowing in the reactor L2 is
It falls from the peak value with time t.

As described above, when a plurality of circuits each including a switching element, a diode and a reactor are connected in parallel to a capacitor, the current flowing through the switching element is the current flowing through the switching element even if the ON resistance of the switching element or the forward voltage of the diode varies. Since it is determined by the value of, if the inductors have the same inductance, the currents will be the same and the loss imbalance of the switching element and the diode can be eliminated.

In the description of FIGS. 1 and 2, the drive pulses are alternately output from the output terminal OUT1 or OUT2 of the control device CT, but it is also possible to output the drive pulses at the same time without alternately, but the drive pulses are alternately output. By outputting, the ripple of the output current ILo can be reduced. That is, when the switching elements Q1 and Q2 are simultaneously operated, the output current ILo has a waveform as shown in FIG. 2F, but when the switching elements Q1 and Q2 of the power supply device of FIG. 1 are alternately operated. The current IL1 flowing through the reactor L1 has a waveform as shown in FIG. 2B, and the current IL2 flowing through the reactor L2 has a waveform as shown in FIG. 2D. Therefore, the output current ILo of the step-down chopper circuit CH is a current obtained by adding the current IL1 flowing through the reactor L1 and the current IL2 flowing through the reactor L2, and has a waveform as shown in FIG. Here, the output ripple of each current waveform is r1 = r2, r1>
r3, r4> r3, and the ripple of the output current decreases when the alternate operation is performed. Therefore, when the switching elements of the power supply device of FIG. 1 are alternately operated, a good output as a DC power supply can be obtained and the capacity of the smoothing capacitor C1 can be reduced, so that a small and inexpensive power supply device can be obtained. .

By the way, there are three types of power supply devices using such a chopper circuit, that is, continuous type, critical type, and discontinuous type power supply devices, and the continuous type has a reactor as shown in FIG. 8 (b). The current IL flowing through L is continuous, the discontinuous type has a discontinuity in the current flowing in the reactor as shown in FIG. 8D, and the critical type has a continuous type as shown in FIG. 8F. When the current flowing through the reactor reaches zero,
The switching element is turned on. A continuous type is preferable to reduce the ripple rate of the output current. In the continuous type, however, since the current IL flowing through the reactor L is continuous, the diode D is turned on when the switching element Q is turned on.
Current is flowing through the switching element Q
As shown in FIG. 8C, a large through current flows when the switching element Q is turned on. For this reason, there is a problem that a loss occurs due to this through current and a temperature rise occurs. On the other hand, in the case of the discontinuous chopper circuit shown in FIG. 8D, when the switching element Q is turned on, no current flows in the diode.
As shown in, only the charging current for the capacitance component of the diode flows, and the through current does not flow. Therefore, as shown in the operation waveform diagram of FIG. 3, if the drive pulses of the power supply device of FIG. 1 are alternately generated to make the chopper circuit a discontinuous type,
As shown in (e), the load current ILo is apparently a continuous type, but each chopper circuit is a discontinuous type, and since a shoot-through current does not occur, a temperature rise due to the shoot-through current does not occur, and the output current ILo does not occur. The ripple rate of ILo can also be reduced. Therefore, by alternately generating the drive pulse of the power supply device and making the chopper circuit a discontinuous type, the loss of the switching element and the diode is reduced and the temperature rise can be suppressed. It is possible to downsize the entire structure of the power supply device.

Next, the case where the power supply device of the present invention is used in an HID lamp drive circuit will be described. High-intensity discharge lamps (HID lamps) such as high-pressure mercury lamps, metal halide lamps, and high-pressure sodium lamps have a low vapor pressure of mercury etc. at the initial stage of transition to arc discharge immediately after starting.
The lamp voltage becomes a low value, and as the mercury vapor pressure rises, the lamp voltage rises as shown in the range of t1 in FIG.

This HID lamp has a large initial voltage variation, and the lamp voltage may increase by a factor of 2 to 3 during use, or the voltage may drop below the rated voltage. Therefore, the steady operation range of such a lamp is wider than the initial rated voltage of the lamp, as shown in FIG. In addition, the HID lamp has a frequency region in which an acoustic resonance phenomenon occurs, and when such an acoustic resonance phenomenon occurs, the light output becomes unstable and flickers, and in some cases, the HID
Since the lamp may be damaged, the frequency of the output current of the power supply device needs to be outside the frequency range in which the acoustic resonance phenomenon occurs.

When the power supply device shown in FIG. 1 is used in a drive circuit for an HID lamp and is operated in a critical type, the loss of the switching element or the diode can be reduced, but the impedance of the load changes to cause switching. Since the switching frequency of the elements Q1 and Q2 changes and the frequency of the output current waveform changes, there is a possibility that the HID lamp enters the frequency region where the acoustic resonance phenomenon occurs. Therefore, when the power supply device shown in FIG. 1 is used for the drive circuit of the HID lamp, the frequency of the current waveform shown in FIG. 3 (e) is set to a fixed frequency and set to a frequency that avoids the region where the acoustic resonance phenomenon occurs.

As described above, if the power supply device shown in FIG. 1 is used in the drive circuit of the HID lamp and is operated at a fixed frequency, as shown in FIG. 4, if the current discontinuous operation is at least within the steady operation range, It is possible to eliminate the influence of the through current flowing through the switching element within the operating range, suppress the output ripple, and prevent the acoustic resonance phenomenon of the HID lamp. Therefore, the size of the HID discharge lamp is small, In addition, it is possible to obtain a good drive circuit without flicker.

In the above embodiment, two circuits each including a switching element, a diode, and a reactor are connected in parallel, but three or more circuits can be connected in line.
By doing so, higher output can be achieved. Further, as described above, it is possible to alternately operate the switching elements or simultaneously operate the switching elements. In addition, the chopper circuit operates in discontinuous operation, continuous operation,
Although a device that performs a critical operation is within the scope of the present invention, the loss due to the through current of the switching element can be reduced by performing the discontinuous operation or the critical operation as described above. Further, in the above embodiments, the step-down chopper circuit is used as the chopper circuit, but the step-up chopper circuit as shown in FIG. 5 or the step-up / step-down chopper circuit as shown in FIG. 6 is used as the chopper circuit. You can also Further, the power supply device of the present invention can be used not only for constant power control but also for constant current control, constant voltage control, and the like, and further controls power, current, and voltage according to a predetermined variation mode instead of being constant. The present invention can also be applied in such cases.

[0026]

As described in detail above, according to the present invention,
A circuit consisting of a switching element, a diode, and a reactor is connected in parallel with a capacitor.Even if there is variation in the ON resistance of the switching element or the forward voltage of the diode, the current flowing through the switching element is the same, Unbalanced diode loss can be eliminated. Therefore, the temperature rise of the switching element and the diode can be suppressed, and the heat dissipation plate and the like can be reduced, so that the power supply device can be downsized. Also, if a plurality of switching elements are operated alternately, the output current becomes a combination of the currents of a plurality of chopper circuits, the ripple rate of the output current can be reduced, and a good output as a DC power supply can be obtained. With
The capacity of the smoothing capacitor can be reduced, and a compact and inexpensive power supply device can be obtained. Furthermore, if the chopper circuit is operated in a discontinuous type, the loss due to the shoot-through current of the switching element does not occur, the effect of the shoot-through current can be eliminated, and the loss of the switching element and the diode is reduced. The temperature rise can be suppressed. Also,
When the power supply device of the present invention is used for a HID lamp and the chopper circuit of the power supply device is discontinuously operated at a fixed frequency, flickering of the lamp and destruction of the lamp can be prevented.
It is possible to obtain a small HID discharge lamp and a good drive circuit without flicker.

[Brief description of drawings]

FIG. 1 is a diagram showing a power supply device according to an embodiment of the present invention.

FIG. 2 is a diagram showing drive pulses and current waveforms of the power supply device shown in FIG.

FIG. 3 is a diagram showing another example of drive pulses and current waveforms of the power supply device shown in FIG.

FIG. 4 is a diagram showing voltage characteristics of an HID lamp.

FIG. 5 is a diagram showing a boost chopper.

FIG. 6 is a diagram showing a step-up / down chopper.

FIG. 7 is a diagram showing a conventional power supply device.

8 is a diagram showing drive pulses and current waveforms of the power supply device shown in FIG.

FIG. 9 is a diagram showing a conventional power supply device for increasing the voltage of a chopper circuit.

[Explanation of symbols]

I input terminal O output terminal Q, Q1, Q2 switching element D, D1, D2 diode L, L1, L2 reactor ra, rb, rc resistance C, C1 capacitor M power calculation circuit CT control circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshifumi Sakata             Meiji Na 3-9-14 Shintaka, Yodogawa-ku, Osaka-shi             Within Sonal Industry Co., Ltd. (72) Inventor Atsushi Ozeki             Meiji Na 3-9-14 Shintaka, Yodogawa-ku, Osaka-shi             Within Sonal Industry Co., Ltd. (72) Inventor Yoshitsugu Tamai             Meiji Na 3-9-14 Shintaka, Yodogawa-ku, Osaka-shi             Within Sonal Industry Co., Ltd. (72) Inventor Nitaro Nagao             Meiji Na 3-9-14 Shintaka, Yodogawa-ku, Osaka-shi             Within Sonal Industry Co., Ltd. (72) Inventor Junichi Kamageya             Meiji Na 3-9-14 Shintaka, Yodogawa-ku, Osaka-shi             Within Sonal Industry Co., Ltd. (72) Inventor Noriaki Nishida             Meiji Na 3-9-14 Shintaka, Yodogawa-ku, Osaka-shi             Within Sonal Industry Co., Ltd. F term (reference) 3K072 AA11 AC12 AC20 BB01 BC01                       CA03 CA06 CA16 CB10 DE02                       DE04 GA03 GB03 GB20                 5H730 AA02 AA14 AA15 AA16 AS05                       AS11 BB13 BB57 BB82 BB89                       DD04 DD32 EE08 EE10 FD01                       FD31 FG01

Claims (4)

[Claims] 1. A chopper circuit comprising a switching element, a diode, a reactor, and a capacitor is provided, and the switching element of the chopper circuit is controlled to be turned on and off,
In a power supply device that controls a load connected to an output terminal, a switching element, a diode,
A power supply device comprising a plurality of reactor circuits connected in parallel. 2. The power supply device according to claim 1, wherein the plurality of switching elements are alternately operated. 3. The power supply device according to claim 1, wherein the chopper circuit is operated in a discontinuous type. 4. A HID lamp drive circuit, wherein the power supply device according to claim 3 is used as a power supply for a HID lamp lighting circuit, and the chopper circuit is operated at a fixed frequency.