JPH03198659A - Power supply device - Google Patents

Abstract

PURPOSE:To reduce breakdown strength of a diode of a rectifier by disposing an electromagnetic energy storing inductance element of a chopper circuit between an AC power supply and the rectifier circuit. CONSTITUTION:A smoothing circuit 4 has a chopper which has a smoothing capacitor 41, an electromagnetic energy storing inductance element 42 and a switching element 50 of an inverter circuit 5, applies the output of a rectifier circuit 3 to the element 50, stores electromagnetic energy in the element 42 when the element 50 is turned ON, and discharges the energy to the capacitor 41 when the element 50 is turned OFF, and the element 42 is inserted between an AC power supply 1 and the rectifier circuit 3. Accordingly, only the switching voltage of the element 50 of the inverter circuit 5 is applied to the rectifier 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a power supply device that receives a commercial AC power source as input and outputs a high-frequency voltage with little low-frequency ripple. It is something that is used.

[Prior Art] Figure 7 shows a conventional power supply device (U.S. Pat. No. 4,564°89).
(see No. 7). This power supply circuit is
A rectifier circuit 3 that full-wave rectifies the AC power source 1, a smoothing circuit 4 that smoothes the pulsating voltage output from the rectifier circuit 3, and is driven by the output of the smoothing circuit 4 to output a high-frequency voltage with little low-frequency ripple. It is composed of an inverter circuit 5,
It drives a load 6 such as a discharge lamp.

FIG. 8 shows a more specific configuration of the power supply device. As shown in the figure, the smoothing circuit 4 includes a smoothing capacitor 41, an inductance element 42, and a switching element 5 of the inverter circuit 5. Then, the output of the rectifier circuit 3 is applied to the switching element 50 of the inverter circuit 5 via the inductance element 42, and when the switching element 50 is turned on, the inductance element 42
This electromagnetic energy is stored in the smoothing capacitor 41 when the switching element 50 is turned off, and the capacitor 41 is charged. As a result, a smooth DC voltage is obtained across the capacitor 41, and by using this smooth DC voltage as the input voltage of the inverter circuit 5, a high frequency voltage with less low frequency ripple can be obtained. Furthermore, since the period during which input current is flowing from the AC power supply 1 becomes longer, the input power factor is improved.

[Problems to be Solved by the Invention] In the conventional example described above, the steep rebound voltage due to the residual energy of the inductance element 42 and the switching voltage of the switching element 50 of the inverter circuit 5 are applied to the rectifier circuit 3. Therefore, the diodes constituting the rectifier circuit 3 require elements with extremely high withstand voltage.
There was a problem that the equipment cost increased.

9(a) to 9(d) show the high-frequency operation of the above-mentioned conventional example, and FIG. 9(a) shows the voltage across the switching element 50. E, the figure (b) shows the current IDC5 flowing through the inductance element 42; the figure (c) shows the inductance element 42
The voltage across both terminals (1) and (d) in the figure is the voltage VDC (-VCE VL) applied to the rectifier circuit 3.

Also, the low frequency changes in this voltage VDC are shown in Figure 9 (E).
Not shown. As is clear from FIG. 9 (Po), the rectifier circuit 3 has a voltage L across the inductance element 42,
Combined voltage VD of the voltage VCH across the switching element 50
C is applied, and this voltage VOC becomes considerably higher than the peak value of the AC power supply voltage. Therefore, it is necessary to use a high-voltage element as the diode of the rectifier circuit 3.

The present invention was made in view of these points, and its purpose is to rectify AC power, smooth it using a chopper-type smoothing circuit, convert it to high-frequency voltage using an inverter circuit, and supply it to a load. The object of the present invention is to reduce the withstand voltage of diodes in a rectifier circuit in a power supply device configured to do so.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
As shown in the figure, a rectifier circuit 3 that performs full-wave rectification of an AC power supply 1
In a power supply device comprising a smoothing circuit 4 that converts the voltage output from the rectifier circuit 3 into a smooth DC voltage, and an inverter circuit 5 that converts the smooth DC voltage output from the smoothing circuit 4 into a high frequency voltage, The smoothing circuit 4 includes a smoothing capacitor 41, an inductance element 42 for storing electromagnetic energy, and a switching element 50 of inverter circuit 1@5, and applies the output of the rectifying circuit 3 to the switching element 50. , the switching element 50
The chopper circuit stores electromagnetic energy in the inductance element 42 when the switching element 50 is turned on, and releases the electromagnetic energy to the smoothing capacitor 41 when the switching element 50 is turned off.
2 is characterized in that it is inserted between the AC power source 1 and the rectifier circuit 3.

[Function] As described above, in the present invention, since the inductance element 42 for electromagnetic energy storage in the chopper type smoothing circuit 4 is inserted between the AC power supply 1 and the rectifier circuit 3,
Only the switching voltage of the switching element 50 in the inverter circuit 5 is applied to the rectifier circuit 3 . Therefore, the withstand voltage of the diode of the rectifier circuit 3 can be reduced.

[Example 1] FIG. 2 is a circuit diagram of a first embodiment of the present invention.

The inverter circuit 5 includes two transistors 50.51 as switching elements, diodes 50a and 51g connected in antiparallel to the transistor 5051, two capacitors 52.53, and a drive voltage applied to the base of the transistor 50.51. It has an output transformer 54 with feedback windings 54c+, 54c2 for applying voltage, and resistors 55-58, and connects a series circuit of transistors 50, 51 and a series circuit of capacitors 52, 53 to input terminal 59. 60 in parallel, and the primary winding 54a of the output transformer 54 is connected between the midpoints of the double-sided column circuit.

Next, the smoothing circuit 4 includes an inductance element 42, a transistor 50 of the inverter circuit 5, and a diode 51a.
and a smoothing capacitor 41, and the AC power supply 1
is applied to one transistor 50 via the inductance element 42 and the rectifier circuit 3, and the smoothing capacitor 41 is connected to the input terminal 59, 60 of the inverter circuit 5, and the switching means of the smoothing circuit 4 is , the transistor 50 of the inverter circuit 5, and the feedback winding 54c+ of the output transformer 54 are reused, and the reverse current blocking means for charging the smoothing capacitor 41 is also constructed using the diode 51a. In the above embodiment, the output transformer 54 has 1 to 50 transistors.
, 51 to control the transistors 54c1 and 54c2 to form an automatic type, but the transistors 50 and 51 are alternately turned on and
Needless to say, it is also good as a separately excited type.

FIG. 3 is an operation waveform diagram showing the high frequency operation of this embodiment, and FIG. 3(a) shows the collector-emitter voltage ■ of the transistor 50. 0, the figure (b) shows the collector current Ie2 of the transistor 51 and the current ID2 of the diode 51a, the figure (c) shows 1 from the collector current IC+ of the transistor 50 and the current of the diode 50a, and the figure (d) shows the rectifier circuit 3.
The waveforms of the voltages Vl)c applied to are shown respectively.

FIG. 4 is an operation waveform diagram showing the low frequency operation of this embodiment, in which (a) shows the power supply voltage VAC of the AC power supply 1; FIG. 4 (b) shows the output voltage VDC of the rectifier circuit 3; c) is the input current IAC2 from the AC power supply 1, and (d) is the voltage across the smoothing capacitor 41. , and (e) of the same figure show the high frequency voltage RF output from the inverter circuit 5, respectively.

The operation of this embodiment will be explained below. Now, when the AC power supply 1 is input to the rectifier circuit 3 via the filter circuit 2 and the inductance element 42, a full-wave rectified DC voltage is output, and this DC voltage is used as the smoothing capacitor 41.
is charged via the diode 51a. The smoothing capacitor 41 is appropriately charged, and the smoothing capacitor 41
I transistor 5 through the starting resistor 55 and 56.
When the base current is supplied to 0°51, the transistor 5
0.51 is turned on and the other is turned off. Next, a feedback winding 54c+ of the output transformer 54 is generated by a vibration circuit formed by the capacitor 52.5B, the primary winding 54a and the secondary winding 54b of the output transformer 54, and the load 6.
A voltage is induced in 54e2 that inverts the on/off state of transistor 50.51, and transistor 50.51 alternately repeats on/off.

A period t+, L3 in FIG. 3 indicates a period in which the transistor 51 is on and the transistor 50 is off, and a period t2 is a period in which the transistor 50 is on and the transistor 51 is off.
When an oscillating current flows through the oscillating circuit 6 and a current 1rH1 flows through the primary winding 54a of the output transformer 54, this current In1 flows through the transistor 5.
0, 51, diode 50a, 51. a, and a current of Inx (n+/n2) flows through the load 6. However, (n1/n2) is the winding ratio between the primary winding 54a and the secondary winding 541).

Note that FIG. 3 shows operating waveforms when the switching frequency of the transistor 50.5 is set higher than the natural oscillation frequency of the oscillation circuit, and the current Inl has a delayed phase.

By the way, during the period t2 in which the transistor 50 is turned on, a shunt current Ic of the current In flows through the transistor 50.
A composite current Ic of the current IDC and the current Dc flowing from the inductance element 42 through the rectifier circuit 3 flows.At this time, electromagnetic energy due to the current IDC flowing through the inductance element 42 is accumulated.Next, during period t2 When the transistor 50 is turned off, the electromagnetic energy accumulated in the inductance element 42 when the transistors 1 to 50 are turned on is transferred to the rectifier circuit 3 and the diode 51.a.
The electromagnetic energy is discharged to the smoothing capacitor 41 through the electromagnetic energy, and the smoothing capacitor 4j is charged by the electromagnetic energy. In this case, the current ID2 flowing through the diode 51a is
The current is a composite current of the shunt current ID2'' of the current fn+ and the output current IDC of the rectifier circuit 3.

As described above, in the first embodiment, the inverter circuit 5
The transistor 50, the diode 51a, and the inductance element 42 constitute a chopper circuit as the smoothing circuit 4, and since the voltage of the switching element is not applied to the rectifier circuit 3, a high voltage diode is not required. Further, since the switching means of the inverter circuit 5 is used to configure a chopper circuit for improving the input power factor, the circuit configuration of the smoothing circuit 4 is simplified and an inexpensive power supply device can be realized.

[Embodiment 2] FIG. 5 shows a second embodiment of the present invention, in which the rectifier circuit 3
A diode 43 is inserted between the DC output terminal of the transistor 50 and the collector terminal of the transistor 50. Since this diode 43 can cut off the high frequency voltage from the switching element applied to the rectifier circuit 3, the rectifier circuit 3 can
It may be configured with a diode with lower breakdown voltage. Note that the other configurations and operations are the same as in the first embodiment, so their explanations will be omitted.

[Example 3] FIG. 6 is a circuit diagram of a third embodiment of the present invention.

The circuit configuration will be explained below. A filter circuit 2 consisting of an inductance element and a capacitor C3 is connected to an AC power source Vs, and connected to an AC input terminal of a full-wave rectifier consisting of diodes D1 to D via this filter circuit 2 and an inductance element L2. A transistor Q1 is connected to the DC output terminal of this full-wave rectifier. Furthermore, a series circuit of a diode D5 and a capacitor C2 is connected in parallel to both ends of the diode D, and a series circuit of a diode D6 and a capacitor C2 is connected in parallel to both ends of the diode D2 to form a step-up chopper circuit. It consists of

On the other hand, diode D's, D6 and capacitor C
A resonant circuit consisting of an inductance element L3 and a capacitor C5 is connected between the connection point of 2 and the collector of the transistor Q, and a resonant circuit consisting of the inductance element L4, the discharge lamp 1a, and the parallel capacitor C1 is connected to the capacitor C.
3 in parallel to form a 6-stone inverter circuit. In this way, the transistor Q is a component of both the chopper circuit and the inverter circuit, and by being used as a switching element, the control circuit becomes one.
This simplifies the configuration.

The operation of this embodiment will be explained below. AC power supply Vs
In the half cycle in which the voltage Vin of is positive, the transistor Q1
When turned on, diode D2D3 is turned on and power supply voltage Vin is applied to inductance element L2. The current flowing through the inductance element L2 increases at a slope proportional to the magnitude of the power supply voltage Vin at that time. When the transistor Q1 is turned off, an induced electromotive force is generated in the inductance element L2, and the diodes D s and D 2
turns on and charges the capacitor C2 with a voltage superimposed on the power supply voltage Vin. As a result, a boost type chopper operation is performed. In the half cycle in which the power supply voltage Vin is positive, the above process is repeated at high frequency.

Next, in the negative half cycle of the power supply voltage Vin of the AC power supply Vs, when the transistor Q1 is turned on, the diode D
+, D4 is turned on, and the power supply voltage Vin is applied to the inductance element L2. At this time, the direction of the voltage applied to the inductance element L2 is opposite to the above. Therefore, in the opposite direction to the above, the power supply voltage Vin
The current in the inductance element L2 increases with a slope proportional to the magnitude of .

When transistor Q1 turns off, inductance element L
2, an induced electromotive force is generated, the diode D6D is turned on, and the capacitor C2 is charged with a voltage superimposed on the power supply voltage Vin. This is also a boost type chopper operation. In the half cycle in which the power supply voltage Vin is negative, the above process is repeated.

On the other hand, in the inverter circuit, regardless of the polarity of the power supply voltage Vin, when the transistor Q is turned on, current flows from the smoothing capacitor C2 to the inductance element L3゜L, and the capacitor C3 is charged to the same voltage as the capacitor C2. The state will be as follows.

Then, when the transistor Q1 turns off, the inductance element L3. As the current continues to flow in the same direction in L<, current flows in the direction shown by the arrow a in the capacitor c3, discharging the charge in the capacitor C3,
Thereafter, capacitor C3 is charged to the opposite polarity. When capacitor C3 is charged to the opposite polarity, capacitor C3
The accumulated charge is discharged into the inductance elements L 3 and L 4, current flows in the direction shown by the arrow, and the capacitor C3 is discharged.

Even when the charge in capacitor C8 is completely discharged, inductance elements L3 and L4 try to continue flowing current in the same direction, so capacitor C3 is further charged to the opposite polarity, and finally reaches the voltage of capacitor C2. It will be charged. When the voltage of capacitor C3 reaches the voltage of capacitor C2, one of the series circuits of diodes D1 to D connected in parallel to transistor Q is turned on, and the current from inductance element L4 flows to the capacitor. C
2 will be returned.

When the power supply voltage Vin is positive, the diodes D, , D:
When l is turned on and the power supply voltage Vin is negative, diodes D 2 and D 4 are turned on and the above feedback current flows.

Therefore, originally, a diode for current feedback in parallel with the transistor Q1 would be required, but in this circuit configuration, the diodes D, -D4 serve the same purpose, so it can be omitted.

In this embodiment, since the chopper circuit is provided on the input side, it is possible to realize an inverter circuit with few harmonic components of the input current and a high input power factor. Moreover, since the chopper circuit and the inverter circuit share the same switching element, the circuit configuration becomes simple. Furthermore, the current feedback diode that should be connected in parallel to the switching element of the one-sided inverter circuit can be omitted.

[Effects of the Invention] As described above, the present invention provides a power supply device in which a smoothing circuit consisting of a chopper circuit is configured between an inverter circuit and an AC power source by utilizing switching elements of an inverter circuit. An inductance element for electromagnetic energy storage is placed between the AC power supply and the rectifier circuit, and the rectifier circuit blocks the reverse current flowing through the inductance element, so a diode for reverse current blocking is separately provided in the chopper circuit. There is an effect that there is no need to use a high-voltage element as a diode constituting the rectifier circuit.

[Brief explanation of drawings]

Figure 1 is a block circuit diagram showing the basic configuration of the present invention, Figure 2 is a block circuit diagram showing the basic configuration of the present invention.
The figure is a circuit diagram of the first embodiment of the present invention, FIGS. 3 and 4 are operational waveform diagrams of the same as above, FIG. 5 is a circuit diagram of the second embodiment of the present invention, and FIG. 6 is a circuit diagram of the second embodiment of the present invention. 7 is a block diagram showing a schematic configuration of a conventional example, FIG. 8 is a block diagram showing a specific configuration of the same, and FIG. 9 is an operation waveform diagram of the same. 1 is an AC power supply, 3 is a rectifier circuit, 4 is a smoothing circuit, 5 is an inverter circuit, 41 is a smoothing capacitor, 42 is an inductance element, and 50 is a switching element.

Claims (1)

[Claims] (1) A rectifier circuit that full-wave rectifies an AC power source, a smoothing circuit that converts the voltage output from the rectifier circuit into a smooth DC voltage, and an inverter that converts the smooth DC voltage output from the smoothing circuit into a high-frequency voltage. The smoothing circuit includes a smoothing capacitor, an inductance element for storing electromagnetic energy, and a switching element of an inverter circuit, and the output of the rectifier circuit is applied to the switching element, It consists of a chopper circuit that stores electromagnetic energy in the inductance element when the switching element is turned on, and releases the electromagnetic energy to the smoothing capacitor when the switching element is turned off. A power supply device characterized in that it is arranged between.