JPH04183277A - power circuit - 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] [Industrial Application Field] The present invention can be used even when power supply voltage fluctuations are large and there is a possibility that the power supply voltage is lower than the voltage required to drive the switch. This invention relates to a power supply circuit suitable for miniaturization.

[Conventional technology]

As described in Japanese Unexamined Patent Publication No. 1-251590, a power supply circuit for a discharge lamp uses a DC power source as a power source, and connects the midpoint of a series circuit using two switch elements and the series circuit of two capacitors. Between the midpoint,
This is a half-bridge discharge lamp lighting circuit in which a load circuit consisting of an inductance, a capacitor, and a discharge lamp is connected, and two switch elements are alternately controlled on and off to supply alternating current to the load circuit. By supplying AC and controlling the frequency of the AC to an appropriate value, the inductance of the load circuit and the resonance state of the capacitor are changed,
The discharge lamp is lit by transitioning from preheating to starting voltage generation to steady lighting.

[Problem to be solved by the invention]

In the above conventional technology, a pulse transformer is used to drive the switch element, so if the turns ratio of the pulse transformer winding is set to an appropriate value, sufficient drive voltage can be generated even if the power supply voltage decreases. On the other hand, the use of the pulse transformer causes problems such as an increase in the size and cost of the device, as well as impediments to higher frequencies and circuit integration due to leakage inductance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply circuit that is compact, can stably obtain a driving voltage, and has the advantages of using a pulse transformer, while eliminating the problems of the conventional technology using a pulse transformer.

[Means to solve the problem]

The above purpose is 1. a switch circuit connecting one end of each of the second switches; the other end of the first switch and the second switch;
DC tg connected between the other end of the switch, the middle point of the switch circuit and the high potential side or low potential side of the DC power supply, or the first and second DC power supplies connected to the Hokugi DC power supply.
a load circuit connected between the midpoint of the capacitor series circuit, a first rectifier whose anode is connected to the high potential side of the DC power supply, and a midpoint between the cathode of the first rectifier and the switch circuit. and a third capacitor connected between.

a second rectifier having an anode connected to the midpoint of the switch circuit; a fourth capacitor connected between the cathode of the second rectifier and the high potential side of the DC power supply; 2
and a switch control circuit that controls on/off of the switch, and supplies alternating current to the load circuit by controlling on/off of the first and second switches, and also controls the second rectifier and the fourth switch. This is achieved by obtaining a voltage approximately twice that of the DC power supply between the connection point with the capacitor and the low potential side of the DC power supply. That is, the switching element is driven using a semiconductor circuit, the control terminal of the switching element is connected to the midpoint of a series circuit of two driving switches, and the other ends of the driving switches are each connected to the driving open DC current 1FA. Then, the switch elements are controlled by turning on one of the drive switches. Furthermore, as the voltage of the driving DC @ source drops below the minimum voltage required to drive the switch element, the on-resistance when the switch element is turned on increases.
In order to prevent power loss from increasing, the power supply voltage is boosted to create a DC power supply for opening, ensuring the necessary voltage at all times.

[Effect]

Since the power supply circuit of the present invention does not use a pulse transformer as described above, it is possible to miniaturize the device and furthermore, it is possible to perform semiconductor integration. Furthermore, since it becomes possible to increase the frequency, it is possible to reduce the size of the negative layer.

In addition, in order to boost DC voltage without using a transformer, it is necessary to turn on and off the boost switching element, convert it to AC, and then boost the voltage using a combination of diodes and capacitors. This leads to an increase in the number of points and causes an increase in costs.

Therefore, the increase in circuit scale due to the addition of the booster circuit was suppressed by making the boost switch element serve as the main switch element that supplies power to the load circuit. Furthermore, by creating a configuration in which an appropriate step-up ratio can be selected depending on the power supply voltage.

Reduced unnecessary power consumption.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of a power supply circuit according to the invention, FIG. 2 is a circuit diagram showing a second embodiment of the invention, and FIG. 3 is a circuit diagram showing a third embodiment of the invention. , FIG. 4 is a circuit diagram showing a fourth embodiment of the invention, FIG. 5 is a circuit diagram showing a fifth embodiment of the invention, FIG. 6 is a circuit diagram showing a sixth embodiment of the invention, and FIG. FIG. 7 is a circuit diagram showing a seventh embodiment of the invention, FIG. 8 is a circuit diagram showing an eighth embodiment of the invention, and FIG. 9 is a circuit diagram showing an embodiment of a load circuit.

The first embodiment shown in FIG. 1 shows an example in which the present invention is applied to a half-bridge inverter, in which 1 is a DC power supply,
2 and 3 are switches, 4 and 5 are capacitors, 6 is a load circuit, 7 and 9 are booster rectifiers, and 8 and 10 are booster capacitors.

11 is an output terminal, and 12 is a switch control circuit.

Switches 2 and 3 are alternately turned on and off by a control signal from the switch control circuit 12.

Therefore, the current changes from the positive side of the DC power supply 1 to the capacitor 4
The flow alternates between the path → load circuit 6 → switch 3 → negative side of DC power source 1, and the positive side of DC power source 1 → switch 2 → load circuit 6 → capacitor 5 → negative side of DC S source 1. Therefore, an alternating current flows through the load circuit 6. By the way, the voltage of the DC power supply 1 is low, and the switch 2
If the voltage is lower than the voltage required to drive 3 and 3, the voltage is boosted by the method shown below, and the boosted voltage is used as the drive voltage. That is, at the same time as the current is supplied to the load circuit 6, while the switch 3 is on, the positive side of the DC power supply 1 → the rectifier 7 for the booster 4 → the booster capacitor 8
A current flows through the path of → switch 3 → the negative side of DC power supply 1, charging the boost capacitor 8 with the power supply voltage, and then when switch 3 is turned off and switch 2 is turned on, both ends of the boost capacitor 8 are Since the low-voltage side terminal of the boosting capacitor 8 is raised to the power supply voltage while maintaining the electric voltage across the terminals, the high-voltage side terminal of the boosting capacitor 8g) is boosted to a voltage twice the power supply voltage. Furthermore, since the boost rectifier 7 is reverse biased at this point, the boost capacitor 10 is charged via the boost rectifier 8. Therefore, a voltage approximately twice the power supply voltage is finally generated at the output terminal 11.

Although one end of the boosting capacitor 1o is connected to the positive side of the DC power supply 1 in this embodiment, the same effect can be obtained even if it is connected to the negative side.

The second embodiment shown in FIG. 2 shows an example of application to a full bridge type inverter. In the figure, 13 and 14 are switches, and the difference is that capacitors 4 and 5 are used in these parts in the first embodiment, and other same symbols indicate the same or equivalent parts as in the first embodiment. In the second embodiment, switches 2 and 14 are turned on and off with the same operation, and switches 3 and 13 are turned on and off with the opposite operation.
Turn off. Therefore, the AC current is supplied to the load circuit 6 through the following path: positive side of the DC power supply 1 → switch 13 → load circuit 6 → switch 3 → negative side of the DC power supply 1.
The low voltage boosting mechanism is the same as that of the first embodiment, in which current alternately flows through the positive side of the switch 2 → load circuit 6 → switch 14 → the negative side of the DC power supply 1) .

As mentioned above, it can also be applied to a full bridge type inverter, and the voltage necessary for driving can be obtained.

Incidentally, in the case of a full-bridge type inverter, a similar effect can be obtained even with a configuration like the third embodiment shown in FIG. The procedure for supplying alternating current to the load circuit 6 is the same as in the second embodiment. In FIG. 3, 15 is a boost rectifier, 16 is a boost capacitor, and other parts with the same reference numerals as in FIG. 2 indicate the same or equivalent parts. Switch 13
and 3 are turned on, the step-up capacitor 16 is connected to the power supply voltage via the positive side of the DC power supply 1 → switch 13 → step-up rectifier 15 → step-up capacitor 16 → switch 3 → negative side of the DC power supply 1. Charge.

The subsequent operations are the same as in the second embodiment.

The first to third embodiments were all examples in which a voltage approximately twice the power supply voltage was obtained. However, there may be cases where a higher boost ratio is required. The fourth embodiment shown in FIG. 4 is a circuit that obtains a boost ratio of three times, in which numeral 17 is a boosting rectifier and 18 is a boosting capacitor.

The process up to charging the boost capacitor 16 is the same as in the third embodiment. Thereafter, when the switches 2 and 14 are turned on, the boosting capacitor 18 is charged with a voltage twice the power supply voltage via the boosting rectifier 17. When the switch 13 is turned on again, the low voltage side terminal of the boosting capacitor 18 is raised to the power supply voltage, so that the boosting capacitor 10 is charged with a voltage approximately three times the power supply voltage via the boosting rectifier 9.

FIG. 5 is a circuit diagram showing a fifth embodiment configured to obtain an arbitrary step-up ratio, and as the number of step-up rectifiers and step-up capacitors is increased, a higher step-up ratio can be obtained.

In FIG. 5, reference numerals 21, 24 and 26 indicate boosting capacitors, and 22, 23 and 25 indicate boosting rectifiers. The boosting mechanism is a repeat of the operation of the fourth embodiment.

The sixth embodiment shown in FIG. 6 is an example in which the output voltage three times higher than that obtained in the fourth embodiment is actually used as a switch drive power supply, and 27 is a drive circuit for switches 2 and 3;
Reference numeral 8 denotes a drive circuit for the switches 13 and 14, and the drive circuits 27 and 28 generate switch drive signals based on a voltage approximately three times the power supply voltage according to the output signal of the switch control circuit 12. 3. Drive 13 and 14.

The seventh embodiment shown in FIG. 7 is an application example where the range of variation in the power supply voltage is large and it cannot be handled by preparing only one step-up ratio, and 28 is a changeover switch, and 29 is a control circuit for the changeover switch. shows.

Using a voltage higher than necessary will lead to an increase in power loss, and in extreme cases, there is a risk that the withstand voltage of the circuit elements will be exceeded and they will be destroyed. Therefore, the changeover switch control circuit 29 detects the output voltage and automatically switches the changeover switch 28 so that an appropriate voltage is obtained, thereby dealing with cases where the power supply voltage fluctuates greatly.

The eighth embodiment shown in FIG. 8 further includes a voltage limiting circuit 30, and is an improvement on the seventh embodiment described above so as to be able to cope with sudden changes in the power supply voltage.

FIG. 9 is a diagram showing an embodiment of the load circuit 6, in which 31 is a transformer, 32 is a choke coil, 33 is a capacitor, and 34 is a diagram showing an embodiment of the load circuit 6.
is a discharge lamp having filaments 35 and 36, and 37 is a preheating capacitor.

The primary side of the transformer 31 has the first embodiment or the second embodiment.
An alternating current flows as explained in the embodiment.

By appropriately controlling the on/off cycles of switches 2, 3, 13, and 14, resonance is generated between the choke coil 32, capacitor 33, and preheating capacitor 37, preheating the filament 35, 36, and dissipating the heat. A voltage is generated across the electric lamp 34 to turn it on.

The above-mentioned load circuit may be a special discharge lamp lighting circuit other than a normal fluorescent lamp lighting circuit, for example, having a short distance between electrodes.

〔Effect of the invention〕

As described above, the power supply circuit according to the present invention is provided between a switch circuit that reads one end of each of the first and second switches, and the other end of the first switch and the other end of the second switch. Connect between the connected DC power supply and the midpoint of the switch circuit and the high potential side or low potential side of the DC power supply, or the midpoint of the first and second capacitor series circuits connected to the DC power supply. a first rectifier having an anode connected to the high potential side of the DC power supply, and a third capacitor connected between the cathode of the first rectifier and the midpoint of the switch circuit; a second rectifier having an anode connected to the midpoint of the switch circuit; a fourth capacitor connected between the cathode of the second rectifier and the high potential side of the DC power supply;
a switch control circuit that controls on/off the first and second switches; Turn on the second switch
By performing the OFF control, alternating current is supplied to the load circuit, and approximately By doubling the voltage, even if the power supply voltage fluctuates greatly, a stable voltage can be maintained without using a transformer. Since integration becomes possible, further miniaturization is possible.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a power supply circuit according to the invention, FIG. 2 is a circuit diagram showing a second embodiment of the invention, and FIG. 3 is a circuit diagram showing a third embodiment of the invention. , FIG. 4 is a circuit diagram showing a fourth embodiment of the invention, FIG. 5 is a circuit diagram showing a fifth embodiment of the invention, FIG. 6 is a circuit diagram showing a sixth embodiment of the invention, and FIG. FIG. 7 is a circuit diagram showing a seventh embodiment of the invention, FIG. 8 is a circuit diagram showing an eighth embodiment of the invention, and FIG. 9 is a circuit diagram showing an embodiment of a load circuit. 1... DC power supply 2... First switch 3.
...Second switch 4...First capacitor 5...
・Second capacitor 6...Load circuit 7...First rectifier 8...
-Third capacitor 9...Second 11 flow device 10...Fourth capacitor 12...Switch control circuit 13...Third switch 14...Fourth switch 15... Third rectifier 29... Changeover switch control circuit 30... Voltage limiting circuit Patent attorney Junnosuke Nakamura 14 f4 phrase Sui Nofu Takunio 3ji 51 Shiiwaka 29
Switching switch → Haqotshi) 3o electric foot vice limit town book. z Figure 5 Figure 6

Claims (1)

[Claims] A switch circuit connecting one end of each of the first and second switches, and a DC power supply connected between the other end of the first switch and the other end of the second switch. and the midpoint of the switch circuit and the high potential side or low potential side of the DC power supply,
Alternatively, a load circuit connected between the midpoint of the first and second capacitor series circuits connected to the DC power supply, and a first rectifier having an anode connected to the high potential side of the DC power supply; a third capacitor connected between the cathode of the first rectifier and the midpoint of the switch circuit; a second rectifier having an anode connected to the midpoint of the first rectifier and the third capacitor; a fourth capacitor connected between the cathode of the second rectifier and the high potential side of the DC power supply;
a switch control circuit that controls on/off the second switch, and supplies alternating current to the load circuit by controlling the first and second switches on/off, and supplies the alternating current to the second rectifier and the A power supply circuit that obtains a voltage approximately twice that of the DC power supply between a connection point with the fourth capacitor and a low potential side of the DC power supply. 2. The load circuit connects the middle point of the switch circuit and the third
, the DC power source is connected between the other end of the third switch and the other end of the fourth switch, and the first to Fourth
The power supply circuit according to claim 1, characterized in that the power supply circuit controls on/off of a switch. 3. The first rectifier has an anode connected to the third switch and the fourth switch.
The fourth capacitor is connected to a connection point of the switch, and one end of the fourth capacitor opposite to the second rectifier is connected to a high potential side or a low potential side of the DC power supply. Power supply circuit described in Section 1. 4. One end of the fourth capacitor opposite to the second rectifier is connected to the connection point of the third and fourth switches, and the anode of the third rectifier is connected to the connection point of the fourth capacitor and the second rectifier. A fifth capacitor is connected between the cathode of the third rectifier and the high potential side or low potential side of the DC power supply, and the first to fourth switches are controlled to be on/off. It is characterized by supplying alternating current to the load circuit, and obtaining a voltage approximately three times that of the direct current power source between the midpoint of the third rectifier and the fifth capacitor and the low potential side of the direct current power source. A power supply circuit according to claim 3. 5. The above-mentioned rectifier has a plurality of rectifiers connected in series with the third rectifier in the same direction, and between the cathode of the odd-numbered rectifier and the anode of the (odd-numbered - 2)-th rectifier. A patent characterized in that a capacitor is connected, this process is repeated an arbitrary number of times, and finally a series circuit of a rectifier and a capacitor is connected between the DC power source and a voltage multiplied by the number of capacitors is obtained. A power supply circuit according to claim 1, 3, or 4. 6. The voltage multiplied by the number of capacitors is the voltage of the first
6. The power supply circuit according to claim 5, wherein the power supply circuit is used as a power supply for driving the first to fourth switches. 7. The power supply circuit according to claim 6, wherein the driving power source selects any one of voltages that are approximately an integral multiple of the DC power source. 8. The power supply circuit according to claim 6 or 7, wherein the driving power source is limited so as not to exceed a predetermined voltage value. 9. Claim 1 or 2 or 4, wherein the load circuit is a lighting circuit for a discharge lamp.
The power supply circuit described in section. 10. Claims 1 to 1, wherein the switch is a boost switch as a component of a boost circuit for obtaining a drive voltage for a switch in a half-bridge inverter or a full-bridge inverter. The power supply circuit described in any of Items 4 or 6.