JPH10337014A - Power supply equipment for electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To average an input power by boosting a DC voltage rectified and smoothened from a commercial power source by a booster type chopper circuit, then storing electric power at a high voltage and to a high density, then lowering its voltage in a voltage drop type chopper circuit, and then returning the electric power energy to a rectified, smoothened capacitor. SOLUTION: A power retaining block P1 boosts an output voltage Vs of a rectifying and smoothening block RS1 from a commercial power source Vin by using a booster type chopper chopper circuit 105, which comprises a rectifying diode bridge 101 and a smoothening capacitor 103, and retains the power in a first capacitor 114 with a voltage V1 higher than the output voltage Vs. Next, the power retained in this first capacitor 114 is returned to the smoothening capacitor 103 of the rectifying and smoothening block RS1 by a voltage drop type chopper circuit 106, and a booster rate, a drop rate and its operation timing are controlled by a control circuit 107. The rectifying block RS1 and the power retaining block P1 are subjected to diode-OR by the third and fourth diodes 108 and 109, and its output is inputted to DC/DC converter 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for an electronic device such as a copying machine or a printer.

[0002]

2. Description of the Related Art In a conventional power supply for electronic equipment,
As a means for rectifying and smoothing a commercial power supply, a method using a full-wave rectifier circuit and a smoothing capacitor as shown in FIG. 2 has been generally used. 2, reference numeral 201 denotes a rectifier diode bridge (DB), 202 denotes a smoothing capacitor (C), 203 denotes a DC / DC converter, and 204 denotes a commercial power supply VIN (A
Outlet C), Iin is the input current. And
The commercial power supply VIN (AC) is rectified by the rectifier diode bridge (DB) 201 and is smoothed by the smoothing capacitor (C).
The rectification and smoothing are performed by smoothing to 202.

[0003]

However, in the above-mentioned conventional example, the power factor is poor and the input power becomes large instead of the power, which is disadvantageous in an electronic device requiring a large power. There was a problem.

[0004] That is, in the outlet 204 of the commercial power supply VIN (AC), the current and power that can be taken out are regulated by law. For example, in Japan, it is necessary to reduce the current to 15 A or less for a general household outlet.
As a countermeasure against this, there has been proposed a method of reducing the power factor to about 1 using a boost type active filter circuit as shown in FIG.

In FIG. 3, reference numeral 301 denotes a rectifier diode bridge (DB); 302, a step-up type active filter circuit; 303, a DC / DC converter; The step-up active filter circuit 302 includes a coil (L) 305, a switching element (Q) 306, a diode (D) 307, and a smoothing capacitor (C) 308. Then, the commercial power supply VIN (AC) is rectified by the rectifier diode bridge (DB) 301, and the smoothing capacitor (C) 3 of the boost type active filter circuit 302.
Rectification is performed by smoothing to 08. In such a method, there are problems that a large amount of power is lost and the cost is disadvantageous.

In electronic devices such as copying machines,
Since a large current flows when the motor or the like is started, the current exceeds 15 A only at that moment. In a high-speed electronic device, it is essential to make the motor start up quickly, and a method of limiting the inrush current, such as making the motor start slow, cannot be adopted. However, the current exceeds 15 A due to the inrush of a mochi or the like, and the current is exceeded only for a limited moment in the entire copying process. In other words, it is not necessary to increase the power factor in all steps of the copying process, and if the input current is limited only for a limited short period, it can sufficiently withstand practical use.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to be suitable for electronic devices such as copying machines and printers that require pulsed power. It is an object of the present invention to provide a small, low-cost, and low-loss power supply device for electronic equipment.

[0008]

According to a first aspect of the present invention, there is provided a power supply apparatus for an electronic device, comprising: a rectifier diode bridge; a smoothing capacitor; a step-up chopper circuit; A first output that includes a first diode and a second diode, rectifies commercial power by the rectifier diode bridge, and smoothes the smoothed capacitor, and boosts the rectified and smoothed first DC voltage. And a second output obtained by stepping up the boosted output by the step-down chopper circuit and stepping down the stepped-up output by the step-down chopper circuit by the first diode and the second diode. Features.

[0009] In order to achieve the above object, a second aspect is provided.
A power supply device for an electronic device according to the present invention is characterized in that, in the power supply device for an electronic device according to the first aspect, the first diode or the second diode is omitted and short-circuited.

[0010] Further, in order to achieve the above object, a third aspect is provided.
3. The power supply device for an electronic device according to claim 2, wherein the first switching element and the second switching element have a duty = 50 ± 5%.
It is characterized in that it is turned on / off at a constant rate.

[0011] In order to achieve the above object, the present invention provides a fourth aspect.
A power supply device for an electronic device according to claim 1, wherein the electronic device is a copying machine.

[0012] In order to achieve the above object, the present invention provides a semiconductor device comprising:
According to a second aspect of the present invention, in the power supply device for an electronic device, the electronic device is a printer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing a configuration of a power supply device of an electronic device according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a rectifier diode bridge (DB);
2 is an input filter, 103 is a smoothing capacitor (electrolytic capacitor) (C), 104 is an outlet of a commercial power supply VIN (AC), 105 is a step-up chopper circuit, 106 is a step-down chopper circuit, 107 is a control circuit, and 108 and 109. Is a diode, and 110 is a DC / DC converter. The step-up chopper circuit 105 includes a first coil (L1) 11
1. First switching element (Q1) 112, first diode (D1) 113, and first capacitor (C1)
114. The step-down chopper circuit 106 includes a second coil (L2) 115 and a second switching element (Q
2) 116, the second diode (D2) 117 and the second
(C2) 118 of FIG.

In FIG. 1, a commercial power supply VIN (AC) is supplied with a rectifier diode bridge 101 and a smoothing capacitor 103.
Block to be rectified and smoothed (rectified and smoothed block) by RS1
And the output voltage is Vs. This output voltage Vs
Is boosted by the boost chopper circuit 105, and the first capacitor 114 holds power at a voltage V1 higher than the output voltage Vs. The power held by the first capacitor 114 is returned to the smoothing capacitor 103 of the rectifying and smoothing block RS1 by the step-down chopper circuit 106,
The control of the step-up rate and the step-down rate by the control circuit 107 and the operation timing thereof is referred to as a power holding block P1.

The rectifying and smoothing block RS1 and the power holding block P1 are diode-ORed by third and fourth diodes 108 and 109. The output is DC /
By inputting to the DC converter 110, a pulse load compatible power supply device is obtained.

Next, the operation of the power supply device of the electronic apparatus according to the present embodiment having the above-described configuration will be described.

The rectifying / smoothing block RS1 is the same as that of a general power supply device.
Power is supplied to the DC / DC converter 110 from the rectifying / smoothing block RS1. Therefore, the power loss is very small as compared with an active filter or the like.

In the step-up chopper circuit 105 of the power holding block P1, since the power is held at the voltage V1 higher than the output voltage Vs, the first capacitor 114 can be made relatively small. When the first capacitor 114 is charged first, the increase in input power can be minimized by charging slowly.

In the step-down chopper circuit 106 of the power holding block P1, the voltage V1 is stepped down during a pulse load, and a voltage Vs' slightly higher than the output voltage Vs is supplied to the DC / DC converter 110. This makes it possible to cope with a pulse load without increasing the power supply from the rectifying and smoothing block RS1. In addition, since the power holding block P1 operates for a short time, it can be realized relatively small thermally.

Next, the control circuit 107 will be described.

In general, V1 = Vs × (Ton + Toff) / Toff in the step-up chopper circuit, and Vs ′ = V1 × Ton ′ / (Ton ′ + Toff ′) in the step-down chopper circuit.

Now, Ton = Ton ', Toff = To
When ff ′, that is, when the first and second switching elements 112 and 116 are driven in synchronization, Vs ′ = Vs × Ton / Toff.

The first and second switching elements 112,
When the switching duty of 116 is fixed to 0.5, the relationship of Vs' = Vs = 1/2 × V1 is established regardless of the value of the input voltage of the commercial power supply, and as if the input smoothing capacitor 10
It looks like the capacity of No. 3 has increased. This eliminates the need to detect the voltage of the smoothing capacitor 103 and control the output voltage of the step-down chopper circuit 106.
This shows that a complicated control circuit considering the delay of the response of the control becomes unnecessary.

Further, when the power of the pulse is taken, the power supply distribution of the rectifying / smoothing block RS1 and the power holding block P1 will be considered.

When the load of the DC / DC converter 110 increases, the output voltage Vs of the rectifying / smoothing block RS1 changes with the input filter, the inrush limiting circuit, the rectifying diode bridge 1
It decreases due to input impedance caused by 01 or the like.
The output voltage Vs' of the power holding block P1 is relatively high because the voltage does not decrease, and the power supply to the DC / DC converter 110 is performed from the power holding block P1.

At a steady load, the power holding block P1 has a circuit loss, so that the output voltage Vs' of the power holding block P1 is slightly lower than the output voltage Vs of the rectifying / smoothing block RS1. Therefore, power is supplied from the rectifying and smoothing block RS1.

As described in detail above, power is supplied from the rectifying / smoothing block RS1 for a "long" stable load, and from the power holding block P1 for a "short" pulse load. That is, the first and second
The initial purpose can be achieved by simple control of the switching elements 112 and 116 having a constant pulse width of 50%.

In practice, the switching duty is set to 0.5 + α in consideration of the circuit loss, and in order to balance the power between the rectifying / smoothing block RS1 and the power holding block P1 at a desired ratio, the impedance of the circuit and the circuit It is necessary to set α to an appropriate value in consideration of the loss.

(Other Embodiments) In the above-described embodiment, the case where switching duty is set to 0.5 + α in consideration of circuit loss has been described. However, the present invention is not limited to this. =
It may be set to 0.5-α.

When set in this way, only when the supply of the commercial power supply is stopped due to a power failure or the like, the operation of releasing the stored and stored power energy is performed to secure a long power holding time. be able to.

If the capacity of the smoothing capacitor 103 of the rectifying / smoothing block RS1 is simply increased to secure a long power holding time, the power factor of the input is deteriorated. Does not deteriorate the input power factor because it is not visible from the commercial power supply side.

[0032]

As described in detail above, according to the power supply device for electronic equipment of the present invention, a DC voltage obtained by rectifying and smoothing a commercial power supply is boosted by a boosting chopper circuit, and power is stored at high voltage and high density. This is stepped down by a step-down chopper circuit, and the power energy is returned to the rectified and smoothed capacitor, so that the input power can be averaged and a power supply circuit that does not take peak power from a commercial power supply can be obtained. .

Thus, a power supply device most suitable for electronic equipment requiring pulse power, such as a copying machine or a printer, which supplies pulse power to a DC / DC converter without taking pulse power from a commercial power supply, can be provided. This has the effect of realizing a small size, low cost, and low loss.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating a configuration of a power supply device of a conventional electronic device.

FIG. 3 is a block diagram illustrating a configuration of a power supply device of a conventional electronic device different from FIG.

[Explanation of symbols]

 101 Rectifier Diode Bridge 102 Input Filter 103 Smoothing Capacitor 104 Outlet 105 Boost Chopper Circuit 106 Buck Chopper Circuit 107 Control Circuit 108 Diode 109 Diode 110 DC / DC Converter 111 Coil 112 Switching Element 113 Diode 114 Capacitor 115 Coil 116 Switching Element 117 Diode 118 Capacitor RS1 Rectifying smoothing block P1 Power holding block

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02M 7/06 H02M 7/06 A 7/217 7/217

Claims (5)

[Claims] 1. A rectifier diode bridge, a smoothing capacitor, a step-up chopper circuit, a step-down chopper circuit, a first diode, and a second diode, and a commercial power supply is rectified by the rectifier diode bridge. A first output smoothed by the smoothing capacitor, and a second output obtained by boosting the rectified and smoothed DC voltage by the boost chopper circuit and reducing the boosted output by the buck chopper circuit. Wherein the first diode and the second diode perform a diode-OR operation. 2. The power supply device for an electronic device according to claim 1, wherein the first diode or the second diode is omitted and short-circuited. 3. The power supply device for an electronic device according to claim 1, wherein the first switching element and the second switching element are turned on / off at a constant duty = 50 ± 5%. 4. A power supply device for an electronic device according to claim 1, wherein said electronic device is a copying machine. 5. The power supply device for an electronic device according to claim 1, wherein said electronic device is a printer.