JP3480248B2 - 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 for obtaining a low frequency rectangular wave output using a commercial AC power supply,
In particular, it is suitable for a discharge lamp lighting device with a high power factor input.

[0002]

2. Description of the Related Art In recent years, a device using a commercial AC power source has been used for a malfunction of an electric device due to a harmonic of a commercial power supply system.
It is desired to reduce the harmonics of the input current so as to approximate a sine wave that is substantially equal to the power supply voltage, and to increase the power factor. The discharge lamp lighting device is no exception, and for that purpose, it is known that a step-up chopper is used as a power factor correction circuit (PFC) and the output DC voltage is received to light the discharge lamp by an inverter. For example, a high-intensity discharge lamp (HID:
High Intensity Discharge
Also in the discharge lamp lighting device for lighting the Lamp, the power factor correction circuit is configured by using the step-up chopper at the input stage, and the polarity is switched to the power conversion circuit by the step-down chopper at the subsequent stage and the polarity at low frequency. By using a combination of circuits or a circuit in which these step-down choppers and polarity switching circuits are integrated, harmonic distortion of commercial input current is reduced, and a HID lamp is stably lit with a low-frequency rectangular wave while maintaining a high power factor. is there.

However, the power factor correction circuit using the booster chopper at these input stages is inevitably expensive and large in size because of the large number of circuit components. Therefore, by combining a power conversion circuit for lighting the discharge lamp and a power factor correction circuit, various circuit systems have been proposed in which the increase in the number of parts is small, the price increase is suppressed, and the shape can be made relatively small. There is.

The circuit shown in FIG. 1 shows an effective means for simultaneously reducing the current increase of the switching element while simultaneously performing the power factor correction circuit and the power conversion to the output in one switching cycle. In the figure, AC is a commercial AC power supply, Q1,
Q1, Q3, and Q4 are high-speed switching elements, D5 and D6
Is a diode, L1 and L2 are inductor elements, EC is a DC smoothing capacitor, C1 is an output smoothing capacitor, and R is a load.

The circuit shown in FIG. 6 is a control circuit for the circuit shown in FIG. 1, and has DRV1, DRV2, DRV3, DRV4.
Is a drive circuit for the switching elements Q1, Q2, Q3, Q4, and OS1 is a basic high-frequency signal oscillator. A signal of the period T1 is generated by the monostable multivibrator MM1 which is triggered by receiving this high frequency signal. The monostable multivibrator MM2 is triggered by the falling edge of the signal in the period T1 to generate the signal in the period T2. The signal in the period T1 and the signal in the period T2 are logically added by the OR circuit OR1 to generate a signal in the period T12 (= T1 + T2). The power supply polarity discriminator PDT outputs a signal according to the polarity of the commercial AC power supply AC, and the voltage V1 of the commercial AC power supply AC.
When the polarity of the signal is in the direction shown in FIG. 1, the signal Po = H
Outputs IGGH. These signals are added to the OR circuit OR2,
By appropriately combining with the gate circuit including the OR3 and the AND circuit group AND, the switching element Q1,
The drive signals d1, d2, d3, d4 for Q2, Q3, Q4 are generated at the timings shown in FIG.

That is, when the polarity of the commercial AC power source AC is as +/- in the figure, first, the switching element Q
3 and Q2 turn on, and after the period T1, the switching element Q
Switching element Q1 turns on at the same time 2 turns off.
However, after the period T2, all switching elements are turned off.
Then, the operation of repeating this switching cycle is performed again at the cycle To of the oscillator OS1. When the polarity of the commercial AC power supply AC is opposite to +/- in the figure, the power supply polarity discriminator PD
The polarity determination signal of T is inverted, and the switching operation is switched as shown in FIG. That is, first, the switching elements Q1 and Q4 are turned on, and after the period T1, the switching element Q1 is turned off and, at the same time, the switching element Q2 is turned on.
However, after the period T2, all switching elements are turned off.
Then, the operation of repeating this switching cycle is performed again at the cycle To of the oscillator OS1.

The above operation will be described in more detail. First, when the polarity of the connection point side of the switching elements Q1 and Q2 of the commercial AC power supply AC is negative, the switching elements Q2 and Q2
3 is ON period T1, switching elements Q1, Q3 is ON period T2, switching elements Q1, Q2, Q
When the polarity of the connection point side of the switching elements Q1 and Q2 of the commercial AC power supply AC is positive, the switching elements Q1 and Q4 are turned off.
Period T1 for N, period T2 for turning on the switching elements Q2, Q4, switching elements Q1, Q2, Q3, Q4
The operation is performed in the order of the period T3 in which the power is turned off.

This power supply device is composed of a first power conversion circuit CNV1 which constitutes a step-up chopper circuit and a second power conversion circuit CNV2 which constitutes a step-down chopper circuit, and the switching elements Q1 and Q2 are each power conversion circuits. It is also used as a circuit. Switching element Q of commercial AC power supply AC
The operation when the polarity of the connection point side of 1 and Q2 is negative will be described for each power conversion circuit that constitutes the step-up or step-down chopper circuit. First, regarding the first power conversion circuit that constitutes the step-up chopper circuit, switching will be performed. The period T2 in which the elements Q1 and Q3 are turned on is a period in which the inductor L1 that acts as a choke of the boost chopper is charged with energy, and the switching elements Q1, Q2, Q3, and Q4 are turned off.
During the period T3 and the switching elements Q2 and Q3
The period T1 for N is a period for discharging the energy stored in the inductor L1. Further, regarding the second power conversion circuit forming the step-down chopper circuit, the period T1 in which the switching elements Q2 and Q3 are turned on is a period in which the inductor L2 acting as the choke of the step-down chopper is charged with energy, and the switching element Q1, Turn on Q3
Period T2 and switching elements Q1, Q2, Q
A period T3 in which 3, Q4 are turned off is a period in which the energy stored in the inductor L2 is discharged.

These will be explained by focusing on the current loop. When the polarity of the connection point side of the switching elements Q1 and Q2 of the commercial AC power supply AC is negative, the switching elements Q2 and Q2.
During a period T1 in which 3 is turned on, a state in which the current of the first power conversion circuit forms a closed loop including the inductor L1, the diode D5, the smoothing capacitor EC, the switching element Q2, and the commercial AC power supply AC, and the second power The current of the conversion circuit is smoothing capacitor EC, switching element Q
3, inductor L2, load R, and switching element Q
A state that forms a closed loop composed of 2 is a period that is established at the same time. Further, the switching elements Q1 and Q3 are turned off.
During the period T2 during which the current flows in the first power conversion circuit, the current in the first power conversion circuit forms a closed loop including the commercial AC power supply AC, the inductor L1, the diode D5, and the switching element Q1, and the current in the second power conversion circuit is This is a period in which the closed loop including the inductor L2, the load R, and the switching elements Q1 and Q3 is simultaneously established. Further, the switching elements Q1, Q2, Q3, Q4 are turned off.
During the period T3, the state of the current of the first power conversion circuit forming a closed loop including the inductor L1, the diode D5, the smoothing capacitor EC, the switching element Q2, and the commercial AC power supply AC, and the second power conversion circuit The current is
This is a period in which the closed loop including the inductor L2, the load R, the switching element Q1, the smoothing capacitor EC, and the switching element Q4 is simultaneously established.

During the period T1, the current flowing in the switching element Q2 in the forward direction by the second power conversion circuit and the current flowing in the reverse direction by the first power conversion circuit are superposed, so that the current flows through the switching element Q2. The current is reduced and the switching loss is reduced. In the period of T2, the current flowing through the switching element Q1 in the forward direction due to the first power conversion circuit and the current flowing in the reverse direction due to the second power conversion circuit are superimposed, so that the current flowing through the switching element Q1 is reduced. This has the effect of reducing switching loss. In the period of T3, the current flowing in the switching element Q2 is reduced by the superimposition of the current flowing in the positive direction by the second power conversion circuit and the current flowing in the reverse direction by the first power conversion circuit. This has the effect of reducing switching loss.

[0011]

In the above-mentioned prior art, when the power supply voltage is low or the inductor L1 is large, the current flow in each switching mode is slightly different even if the switching operation is the same. Commercial AC power supply A
The operation when the polarity of the connection point side of the switching elements Q1 and Q2 of C is negative will be described by focusing on the current loop, and the period T1 in which the switching elements Q2 and Q3 are turned on is the second
The current of the power conversion circuit is a period during which a state forming a closed loop including the smoothing capacitor EC, the switching element Q3, the inductor L2, the load R, and the switching element Q2 is established, and a period T2 during which the switching elements Q1 and Q3 are turned on. Is a state in which the current of the first power conversion circuit forms a closed loop composed of the commercial AC power supply AC, the inductor L1, the diode D5, and the switching element Q1,
This is a period during which the current of the second power conversion circuit is simultaneously established with a state forming a closed loop including the inductor L2, the load R, and the switching elements Q1 and Q3, and is a period during which the switching elements Q1, Q2, Q3, and Q4 are turned off. T3
Has the following two states depending on the magnitude relation between the currents flowing through the inductors L1 and L2.

First, when the absolute value of the current of the inductor L1 is smaller than the absolute value of the current of the inductor L2, the current of the first power conversion circuit is the commercial AC power supply AC, the inductor L1, the diode D5, the smoothing capacitor EC, And a state forming a closed loop composed of the switching element Q2,
A state in which the current of the second power conversion circuit forms a closed loop including the inductor L2, the load R, the switching element Q1, the smoothing capacitor EC, and the switching element Q4 is simultaneously established. Further, when the absolute value of the current of the inductor L1 matches the absolute value of the current of the inductor L2, the currents from the first power conversion circuit and the second power conversion circuit are canceled by each other, and as a result, the switching element is also used. The total sum of the inflowing currents becomes 0, and in effect, the closed loop of the current passing through the dual-purpose switching element is not formed inside each power conversion circuit, and the inductor L1,
Diode D5, smoothing capacitor EC, switching element Q4, inductor L2, load R and commercial AC power supply AC
The state that constitutes the closed loop consisting of is established. During this period, a closed loop of the current passing through the dual-purpose switching element is not formed. Therefore, although the power conversion circuit is operating, no current flows in the switching elements Q1 and Q2, so that no power loss occurs. .

As described above, in the circuit system of FIG. 1, it is possible to efficiently obtain a rectangular wave output synchronized with the polarity of the commercial AC power supply AC while fusing the two choppers for boosting and stepping down. However, the step-up chopper that is the first power conversion circuit functions as a power factor correction circuit, and provides a suitable power conversion device that can be reduced in cost and downsized.

However, a series of switching cycles are equal over one cycle of the power supply AC, that is, one cycle of the output,
Further, the switching section in which power is mainly supplied from the smoothing capacitor EC to the load R and the switching section in which energy is stored in the inductor L1 from the power supply AC are provided in the power supply A.
In the case where all are fixed to a predetermined time during one cycle of C, if the capacitance of the smoothing capacitor EC is large and the voltage is substantially constant, the output waveform can be expected to be a rectangular wave, but in reality, Although the voltage of the smoothing capacitor EC is almost constant, there is a phenomenon that the output is reduced around the valley of the power supply voltage.

This is because the peak and the valley of the power supply voltage are
This is because the current path has a difference as shown in FIGS. That is, in FIGS. 8 and 9, (a) and (b)
The switching conditions are the same in the section. But,
There is a difference in the route of (c). In FIG. 8 (c), the loop of the current flowing through the load recirculates through the diodes D2 and D4, whereas in FIG. 9 (c), energy is regenerated to the smoothing capacitor EC via the diodes D1 and D4. is doing. At this time, the load circuit and the inductor L2
The voltage of the smoothing capacitor EC is applied as a reverse voltage. As a result, the output voltage drops.

In the section of FIG. 9C, the inductor L
Since the currents i1 and i2 flowing in 1 and L2 respectively become equal, the power supply voltage is low and the difference between i1 and i2 at the time of shifting from FIG. 9B to FIG.
Since the period of FIG. 9C continues for a long time, the output decreases. As a result, in the case of a waveform, such as a sine wave, in which the absolute value of the power supply voltage fluctuates during one cycle, ripples occur in the output. Further, when the voltage of the smoothing capacitor EC is lowered, the step-up ratio of the step-up chopper is lowered, so that the input current is distorted, resulting in a triangular waveform as shown in FIG.

The present invention is intended to solve such a problem, and an object of the present invention is to provide a power supply device in which a switching circuit for performing a plurality of power conversions shares a switching element, in the vicinity of a low voltage of a commercial AC power supply. It is an object of the present invention to provide a means for reducing the distortion of the input current waveform.

[0018]

According to the present invention, in order to solve the above-mentioned problems, at least two power conversion circuits each having at least one switching element are provided.
At least one of the switching elements is also used as an element constituting at least two different power conversion circuits, and at least one of the currents from the different power conversion circuits flowing into the combined switching elements is at least 1 A power supply device comprising a control means having at least a period in which a current flowing from one power conversion circuit has a polarity opposite to that of a current flowing from another at least one power conversion circuit and flows in directions canceling each other. In the cycle, the dual-purpose switching element has a switching period that mainly takes current from the power source of the first power conversion circuit, and the switching period is changed according to the voltage value of the input power source. To do.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the power supply device of FIG. 1, a series circuit of switching elements Q1 and Q2 and a switching element Q
A series circuit of Q3 and Q4 and a series circuit of diodes D5 and D6 are connected in parallel across the electrolytic capacitor EC. Further, an inductor L2 and a load circuit Z are connected between the connection point of the switching elements Q1 and Q2 and the connection point of the switching elements Q3 and Q4, and the diode D
An AC power supply AC and an inductor L1 are connected between the connection point of 5, 5 and the connection point of the switching elements Q1, Q2. 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 switching elements Q1 and Q2 of the input AC power source has a negative polarity, the switching elements Q2 and Q3
Is ON, the switching elements Q1 and Q4 are OFF, and the switching elements Q1 and Q3 are ON, and the switching elements Q2 and Q4 are OFF, and all the switches are ON.
There is a period in which the ching element is OFF in order, and the elements operate so as to repeat them periodically. When the connection point side of the switching elements Q1 and Q2 of the input AC power source has a positive polarity,
The period in which the switching elements Q1 and Q4 are ON and the switching elements Q2 and Q3 are OFF, and the switching element Q
2 and Q4 are ON, switching elements Q1 and Q3 are O
The FF period and the period in which all the switching elements are OFF are in order, and they operate so as to repeat them periodically. By operating the circuit as described above, a rectangular wave voltage synchronized with the input commercial frequency power supply AC is applied to the load R.

The switching element Q which is also used
Since the currents of 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 and the cost is low. The power supply device can be provided.

In the present invention, the voltage value V1 of the input power supply AC is obtained by adopting the control circuit as shown in FIG. 2 or 4 in the power supply device as shown in FIG.
Alternatively, the switching period is changed according to the voltage value V2 of the load R to improve the input current distortion or the output current distortion. The specific configuration of the control circuit will be described below.

[0023]

【Example】

(Embodiment 1) FIGS. 1 and 2 show Embodiment 1 of the present invention.
The configuration of the main circuit shown in FIG. 1 is as described above. The configuration of the control circuit shown in FIG. 2 is an improvement of the basic circuit of FIG. 6, and an absolute value detector ABS and an error amplifier EA are newly added. Further, the monostable multivibrator MM2 that determines the switching period T2 is a voltage-controlled monostable multivibrator, and the switching period T2 can be varied according to the voltage applied to the control input terminal CT.

In this embodiment, the absolute value Vaa of the instantaneous voltage of the commercial AC power supply AC is detected by the detector ABS, and this is compared with the reference value by the error amplifier EA to measure the difference, and the obtained error voltage Vea is obtained. Is added to the control input terminal CT of the monostable multivibrator MM2. The so-called PWM control is performed such that the switching period T2 is shortened when the voltage of the commercial AC power supply AC is high, and the switching period T2 is lengthened when the voltage of the commercial AC power supply AC is low. As a result, the insufficient current in the valley of the power source can be supplied to the commercial AC power source AC.
The average value waveform of the input current is
It is improved as shown in.

(Second Embodiment) FIGS. 1 and 4 show a second embodiment of the present invention. The configuration of the main circuit shown in FIG. 1 is as described above. The configuration of the control circuit shown in FIG. 2 is an improvement of the basic circuit of FIG. 6, and a load voltage detector V2DT, an absolute value detector of the power supply voltage ABS, a clamp circuit CLP, and error amplifiers EA and EA2 are newly added. ing. The monostable multivibrators MM1 and MM2 that determine the switching periods T1 and T2 are voltage-controlled monostable multivibrators, and the switching periods T1 and T2 are set according to the voltage applied to the control input terminal CT. It can be changed.

The above-described first embodiment was effective for improving the input current waveform. When this device is used for a HID lighting device, for example, a flat output is desirable for stable lighting. However, as shown in the conventional example, the rectangular wave of the output current is not flat but has distortion. Therefore, in the second embodiment, in order to stabilize the output, the load voltage V2
Is detected by the detector V2DT, and this is compared with the reference voltage Vref by the error amplifier EA2 to apply the voltage of the error amplifier EA2 to the control terminal of the T1 period provided in the monostable multivibrator MM1. Is added with means for performing PWM control so that the voltage V2 of the load becomes substantially constant. FIG. 5 shows operation waveforms of this embodiment,
Good input / output waveforms are obtained.

[0027]

According to the present invention, the power factor improving performance and the output stability can be further improved with a simple additional circuit, so that a small-sized and high-performance rectangular-wave output can be obtained with a commercial AC power supply input. There is an effect that a good low-cost power supply device or lighting device can be provided.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a main circuit of a power supply device of the present invention.

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

FIG. 3 is a waveform diagram showing input / output waveforms according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a control circuit used in a second embodiment of the present invention.

FIG. 5 is a waveform diagram showing input / output waveforms of a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a control circuit used in a conventional example.

FIG. 7 is a waveform diagram showing the operation of the control circuit used in the conventional example.

FIG. 8 is a circuit diagram showing an operation in a mountain portion of a conventional power supply.

FIG. 9 is a circuit diagram showing an operation in a valley portion of a conventional power supply.

FIG. 10 is a waveform diagram showing input / output waveforms of a conventional example.

[Explanation of symbols] Q1-Q4 switching elements D5, D6 diode AC AC power supply L1 First inductor L2 second inductor EC smoothing capacitor R load

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Hizuma, 1048, Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Works, Ltd. (72) Toshiro Nakamura, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. (56) References JP-A-4-58767 (JP, A) JP-A-9-93955 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02M 7/48 H02M 7 / 5387 H05B 41/16 H05B 41/24

Claims (12)

(57) [Claims] 1. At least two power conversion circuits each comprising at least one switching element,
At least one of the switching elements is also used as an element forming at least two different power conversion circuits, and at least one of the currents from the different power conversion circuits flowing into the combined switching element is at least one power conversion circuit. The current flowing in from at least one other
A power supply device comprising a control means having at least a period in which the currents flow from one power conversion circuit have a polarity opposite to that of the currents flowing in a direction in which they cancel each other. What has a switching period which mainly takes in current from the power supply of a power conversion circuit, and changes this switching period according to the voltage value of an input power supply. 2. Of at least two different power conversion circuits, a first power conversion circuit has at least a closed loop including at least the switching element having the dual function and a power supply and a first inductor. The second power conversion circuit is configured to have a closed loop including at least the switching element that is also used as the power conversion circuit, a load circuit, a second inductor, and a capacitor. 1. The power supply device according to 1. 3. The first power conversion circuit is configured as a step-up chopper circuit or a step-up / step-down chopper circuit, and
3. The power supply device according to claim 2, wherein the power conversion circuit is configured as a step-down chopper circuit. 4. The first power conversion circuit is a power conversion circuit which receives a commercial AC power supply as an input and stores a DC output voltage in a capacitor, and the second power conversion circuit receives a DC voltage of the capacitor as an input. 4. The power supply device according to claim 3, wherein the power supply circuit is a power conversion circuit. 5. The length of the switching period in which the current is mainly taken from the power source of the first power conversion circuit is changed at least when the instantaneous voltage of the commercial AC power source is equal to or less than a predetermined value. The power supply described. 6. The switching period in which a current is mainly fetched from the power supply of the first power conversion circuit, when the current of the second inductor becomes larger than the current of the first inductor immediately before the end of the switching period. The power supply device according to claim 1, wherein the length of the switching period is changed. 7. The switching period in which the second power conversion circuit draws current mainly from the DC voltage of the capacitor,
7. The power supply device according to claim 1, wherein the power supply device is changed according to the output of the second power conversion circuit. 8. A power supply device, characterized in that the switching period according to claim 7 is changed so that the output current and / or the output voltage of the second power conversion circuit becomes substantially constant. 9. The power supply device according to claim 1, wherein the output of the second power conversion circuit is a low frequency rectangular wave. 10. A circuit in which first and second switching elements each having a reverse current-carrying element in parallel are connected in series so that their forward directions match, and third and third circuits each having a reverse-current-carrying element in parallel. A circuit in which the switching element of 4 is connected in series so that the forward direction is matched is connected in parallel with the capacitor with the same polarity, and a circuit in which two rectifying elements are connected in series has a reverse polarity with respect to the capacitor. And a series circuit of an AC power supply and a first inductor is connected between the connection point of the two rectifying elements and the connection point of the first and second switching elements, and the first and second 2. A circuit configuration in which a series circuit of a load circuit and a second inductor is connected between a connection point of the switching element of and a connection point of the third and fourth switching elements. 9. The power supply device according to any one of 9. 11. The power supply device according to claim 10, wherein the first to fourth switching elements provided with the reverse conduction elements in parallel are field effect transistors each having an antiparallel parasitic diode. . 12. The power supply device according to claim 1, wherein the load is a discharge lamp.