JP2008061492A - Power supply unit and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the excessive load on the main power supply, when supplying electric power to a load by using a main power supply and an auxiliary power supply. <P>SOLUTION: The power supply unit supplies electric power to the load by using the main power supply and the auxiliary power supply, detects the current and the voltage of the auxiliary power supply, to prevent excessive load on the main power supply, when the output of the detected result is different from preset value, by adjusting the control current to the main power supply, in accordance with the degree of this difference. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply apparatus and an image forming system that have a main power supply and an auxiliary power supply, and in particular use an electric double layer capacitor as the auxiliary power supply.

  When supplying all power from a main power source such as a battery or DCPS (DC Power Supply System) to a load having a peak, it is necessary to match the power supply capability of the main power source to the peak. However, this has led to an increase in equipment size and cost, such as increasing the output transformer of the DCPS.

On the other hand, in order to solve the above problem, a method has been proposed in which an auxiliary power source using an electric double layer capacitor (hereinafter simply referred to as a capacitor) is combined with the main power source.
For example, a power supply control unit for controlling the current supplied from the power supply unit is provided between the power supply unit and the energy storage unit having the capacitor, and when the output voltage of the power supply unit decreases, the supply current from the main power supply is reduced. A method of supplying insufficient power from a capacitor has been proposed (see Patent Document 1).

  Also, using a variable impedance such as a thermistor that has a positive temperature coefficient of resistance between the power supply and the capacitor, if a large current flows through the load, the current from the main power supply will increase using the value of the variable impedance being large. There has been proposed one in which supply is suppressed and current is supplied exclusively from a capacitor (see Patent Document 2).

However, the configuration in which the internal impedance of the capacitor used as the auxiliary power supply is higher than the internal impedance of the main power supply has a problem that it does not function sufficiently as the auxiliary power supply.
This problem is explained as follows.
Capacitors generally have a low internal impedance per cell but a withstand voltage as low as 2.5 V. Therefore, when used as an auxiliary power source as in the above example, the withstand voltage must be increased, so a plurality of capacitors must be connected in series. . In this case, for example, if ten cells having an internal impedance of 100 mΩ with a withstand voltage of 2.5 V are connected in series, the withstand voltage is 25 V / internal impedance of 1Ω.
In contrast, a nickel metal hydride battery as a main power source has an internal impedance of about 5 mΩ per cell (1.2 V), and when it is connected in series to achieve 25 V, the internal impedance becomes about 100 mΩ. On the other hand, when DCPS is used as the main power source, the internal impedance is about several tens of mΩ to several hundreds of mΩ.
Therefore, the internal impedance of the auxiliary power supply may be higher than the internal impedance of the main power supply.

Thus, when the internal impedance of the auxiliary power supply becomes higher than the internal impedance of the main power supply, the current that should be supplied from the auxiliary power supply side at the peak load current is almost the main power supply because the internal impedance is high. Therefore, there is a problem that it does not perform its original function as an auxiliary power source. For this reason, the charging energy of the capacitor cannot be used.
Further, when a current is supplied from the capacitor, a voltage drop based on the internal impedance occurs, so that there is a problem that the minimum operating voltage on the load side cannot be maintained.

JP 2003-250228 A JP-A-7-75251

  The present invention has been proposed in order to solve the above-described problems, and is a combination of a main power source and an auxiliary power source composed of an electric double layer capacitor, and exhibits the function of the auxiliary power source. It is an object of the present invention to provide a power supply device and an image forming system that can utilize the charging energy stored in the capacitor and can maintain the minimum operating voltage on the load side.

In order to achieve the above object, the present invention employs the following configuration.
Here, an outline of the present invention will be described.
The present invention uses a main power supply and an auxiliary power supply to supply power to a load, and distributes them to each other. When the load current reaches a peak, the current and voltage generated in the auxiliary power supply are When the detected value exceeds the set value or falls below the set value, the output current of the main power supply is controlled.

  Claim 1 is a power supply device that is connected to a main power source, an auxiliary power source composed of an electric double layer capacitor, and a load, and supplies power to the load by sharing the main power source and the auxiliary power source. An output power detection unit that detects an output of the auxiliary power source, and a power control unit that controls a value of an output current of the main power source based on a detection output of the output detection unit. is there.

  According to a second aspect of the present invention, the output detection means is current detection means for detecting an output current of the auxiliary power source, and the power control means is configured such that the detection output from the current detection means is a first set value that is set in advance. The output current value of the main power supply is controlled to be decreased when the output current value is smaller than the value, or the output current value of the main power supply is increased when the output current value is larger than the second set value. The power supply device according to Item 1.

  According to a third aspect of the present invention, the output detection means is voltage detection means for detecting an output voltage of the auxiliary power supply, and the power control means is configured such that the output of the voltage detection means is based on a preset third set value. 2. The power supply device according to claim 1, wherein the power supply device is controlled so as to increase an output current value of the main power supply when the power supply voltage is lower.

  Claim 4 is a power supply device to which a main power source, an auxiliary power source composed of an electric double layer capacitor, and a load are connected, and the main power source and the auxiliary power source are shared to supply power to the load. The current detection means for detecting the output current of the auxiliary power supply, the voltage detection means for detecting the output voltage of the auxiliary power supply, the output of the current detection means and the predetermined set value are compared, and In response, a current detection processing unit that outputs a control signal for decreasing or increasing an output current value of the main power supply is compared with an output of the voltage detection means and a preset set value, and the detected voltage is lower than the set value. A power detection means comprising a voltage detection processing section for outputting a control signal for increasing the output current of the main power supply when low, a switching means for switching the output of the current detection processing section and the voltage detection processing section, and the switching A power supply device and having an input means for supplying a switching signal to the stage.

  According to the fifth aspect, when the internal impedance of the main power source is Zm and the internal impedance of the auxiliary power source is Zc, the current value supplied from the main power source is Is (A) satisfying the relationship of Zm ≦ Zc, and the load The peak current is ILpeak (A), the voltage drop allowable width of the auxiliary power supply is ΔVCAP (V), and the auxiliary power supply voltage drop width per cycle of the load current by supplying power from the auxiliary power supply to the load is ΔVL (V) 5. The power supply device according to claim 1, wherein a relationship of Is ≧ ILpeak− (ΔVCAP−ΔVL) / Zc is satisfied.

  A sixth aspect of the present invention is an image forming system in which the power supply device according to any one of the first to fifth aspects is incorporated in a post-processing apparatus of the image forming apparatus.

  Provided a power supply apparatus capable of reducing the burden on the main power supply by controlling the distribution of the power supply when supplying power to the load using the main power supply and the auxiliary power supply, and an image forming system using the power supply it can.

  Embodiments of the present invention will be described below.

FIG. 1 is a schematic block diagram of the present invention.
Reference numeral 1 denotes a main power supply / charger (hereinafter referred to as main power supply), which is constituted by an AC / DC converter, a DC / DC converter, or a storage battery.
Reference numeral 2 denotes a load which is driven by being supplied with power from the main power source 1.
Reference numeral 3 denotes an auxiliary power source, which is configured by connecting a plurality of capacitors C1 to Cn in series, and assists power supply from the main power source 1 to the load 2.
The main power source 1 and the load 2 are directly connected, and the auxiliary power source 3 is connected to the connection path between the main power source 1 and the load 2 via the current detecting means 4 in order to detect a current supplied from the auxiliary power source. It is connected. A voltage detection means 5 for detecting the output voltage of the auxiliary power supply, that is, the voltage applied to the load 2 is connected between the connection path and the connection terminal between the main power supply 1 and the load 2.
Reference numeral 6 denotes a control means, which is related to the current Ic supplied from the auxiliary power supply, and receives the Vic output from the current detection means 4 and the output Vh from the voltage detection means 5 and receives a control signal for the main power supply 1. Vin is transmitted.

Here, the power supply apparatus to which the present invention is applied is preferably set to specifications that satisfy the following relationship.
The internal impedance of the main power source 1 is Zm, the internal impedance of the auxiliary power source 3 is Zc, the maximum current value supplied from the main power source 1 is Is (A), and the peak current of the load 2 is ILpeak (A), the allowable voltage drop width of the auxiliary power supply 3 is ΔVCAP (V), and the auxiliary power supply voltage drop width per cycle of the load current by supplying power from the auxiliary power supply 3 to the load 2 is ΔVL (V) Is set so as to satisfy the relationship Is ≧ ILpeak− (ΔVCAP−ΔVL) / Zc.

FIG. 2 shows an example in which the control means 6 is configured by software.
That is, a CPU (Central Processor Unit) 6A and a memory 6B including a ROM (Read Only Memory) and a RAM (Random Access Memory) are provided. The CPU 6A includes an A / D converter 6D that converts the output Vic of the current detection means 4 into a digital signal, an A / D converter 6E that converts the output Vh of the voltage detection means 5 into a digital signal, An arithmetic unit 6C that receives digital signals from the A / D converters 6D and 6E and performs comparison with a set reference value, a difference operation, and the like, and a D / A conversion that converts an arithmetic result signal from the arithmetic unit 6C into an analog signal A container 6F is provided.

  The ROM in the memory 6B stores a program according to flowcharts shown in FIGS.

  Next, the operation of the present invention will be described with reference to the time charts of FIGS. 3A, 3B and 4 and the flowcharts shown in FIGS.

Prior to the description of the operation, the outline of the time charts of FIGS. 3A, 3B and 4 will be described.
In FIG. 3A, the load current IL, auxiliary power supply current Ic, and main power supply current Is are arranged on the vertical axis, and the horizontal axis is the time axis. I1 indicated by the dotted line is the first setting in the present invention. It is a value. The first set value is a current value to be borne by the auxiliary power supply when supplying a current to the load, in other words, for suppressing the maximum current borne by the main power supply.
FIG. 3B is the same as the arrangement of FIG. 3A, and the current I2 indicated by the dotted line is the second set value. This second set value is to prevent premature discharge as a result of supplying more current than expected from the auxiliary power supply due to variations in the internal impedance of the capacitor, in other words, the maximum burden of the auxiliary power supply. This is for suppressing the current and for the main power supply to bear that much.
In FIG. 4, the load current IL, the auxiliary power supply current Ic, the auxiliary power supply voltage Vc, and the main power supply current Is are arranged on the vertical axis, the horizontal axis is the time axis, and the voltage Vc3 indicated by the dotted line is the third value. It is a set value. This third set value is for suppressing the voltage drop due to the internal impedance accompanying the current supply from the auxiliary power supply. In other words, the current supplied to the load is appropriately shared by the main power supply and the auxiliary power supply. This is for suppressing the voltage applied to the load.

(Current detection operation)
First, the current detection control operation mainly using FIG. 5 will be described.
In the following description of the operation, it is assumed that the maximum current supplied from the main power source 1 which is a constant current source can be varied from 1A to 5A, and the initial value is set to 3A.
First, as initial settings, the reference values I1 (first set value) and I2 (second set value) of the power supplied from the auxiliary power supply 3 and the maximum current value Is (3A in this case) supplied from the main power supply are set. (Step S1).

Next, it is determined whether the load 2 is ON / OFF (step S2).
Next, when the load 2 is ON and power is supplied to the load, the current Ic of the auxiliary power supply 3 is detected by the current detection unit 4 and the detection result is input to the control unit 6.
The control means 6 compares the detected current Ic with the set value I1 to determine whether Ic is smaller than I1 (step S3). If there is a relationship of Ic <I1, then the first set value I1 is set. A difference value of Ic (I1−Ic = ΔI) is calculated, and a new set value (Is ′ = Is−ΔI) is set to decrease the output current Is of the main power supply (that is, the load of the auxiliary power supply is reduced). (Step S4).

  Next, it is determined whether or not the new output current Is ′ of the main power supply set as described above does not fall below a variable range lower limit (for example, 1A) (step S5). Control to change is performed (step S6). If the value is not below the lower limit value, the new set value is maintained (step S7).

  If it is determined in step S3 that the auxiliary power supply current Ic is not smaller than the first set value I1, then whether or not (Ic) is greater than the second set value I2 (Ic> I2). Is determined (step S9).

  When it is determined that Ic> I2, the difference (ΔI = Ic−I2) is calculated, and control is performed with a new set value (Is ′ = Is + ΔI) based on the difference (ΔI = Ic−I2). To reduce the burden on the auxiliary power supply (step S10). It is determined whether or not the new current value Is ′ of the main power supply set in this way exceeds the upper limit (for example, 5 A) of the variable range of the main power supply (step S11), and the new current value Is ′ is 5 A. If it exceeds the value, the change control is performed so that it becomes 5 A (step S12). If not, the new set current value is maintained (step S13).

  Finally, it is determined whether or not the load 2 is turned off. If it is not turned off, the process returns to the initial flow, and if it is turned off, the process ends (step S8).

(Voltage detection operation)
Next, the voltage detection control operation will be described with reference to the flowchart of FIG.
As a premise for the following operation description, it is assumed that the maximum current supplied from the main power supply can be varied from 1 A to 5 A, and the current instruction to the main power supply is in increments of 0.5 A.

  First, initial setting is performed. That is, the third set value Vc3 is set as the reference value of the auxiliary power supply voltage, and the initial value of the maximum current value supplied from the main power supply is set to 3A (step S21). Next, it is determined whether the load is on or off. If the load is on, the process proceeds to the next step (step S22).

  The voltage Vh of the auxiliary power supply is detected by the voltage detection means 5 to determine whether or not it is smaller than the third set value Vc3 (step S23). If Vh <Vc3, a new output current value Is ′ of the main power supply is determined. Set. In this case, the value is increased by 0.5A (step S24). In this way, the burden on the main power source is increased to reduce the burden on the auxiliary power source.

  Then, it is newly determined whether or not the set current Is ′ exceeds 5 A (step S 25), and if it exceeds, it is reset to 5 A (step S 26), and if it does not exceed, a new set value is maintained (step S 27). ). Finally, it is determined whether or not the load is turned off. If it is not turned off, the process returns to the first flow, and if it is turned off, the process ends (step S28).

Next, a case where the power supply device of the present invention is configured by hardware will be described with reference to FIG.
A specific configuration example of the control means 6 is shown in FIG.
The control means 6 inputs the output Vic of the current detection means 4 to the + side terminal, the first comparator COM1 having the first set value Vref1 input to the inversion side terminal, and the output Vic to the inversion side input terminal. And the second comparator COM2 in which the second set value Vref2 is input to the + terminal, and the outputs of the first and second comparators COM1 and COM2 are used to obtain three-stage voltage values V1, V2, and V3. A first changeover switch SW1 for switching, a third comparator COM3 for inputting the output Vh of the voltage detection means 5 to the + side input terminal, and a third set value Vref3 to the inverting input terminal; According to the output of the comparator COM3, the second change-over switch SW2 for switching to one of the two voltage values V4 and V5 and the output of the first and second change-over switches Is constructed either from the third change-over switch SW3 Metropolitan switching based on the external switching signal.
Here, the external switching signal detects the output current of the auxiliary power source 3 and controls the maximum output current of the main power source according to the result (current detection control path), and detects the output voltage of the auxiliary power source. As a result, one of the cases where the maximum output current of the main power source is controlled (voltage detection control path) is switched, and can be arbitrarily selected.

  The operation of the control means 6 that performs the above operation will be described with reference to FIGS. 3 and 4 again.

(Current detection operation)
First, processing of signals from the current detection means 4 shown in the lower part of FIG. 7 will be described. In this case, it is assumed that the external switching signal switches the third switch means SW3 to the first switch means SW1 side.

  The output Vic from the current detection unit 4 is input to the control unit 6 and input to the plus side input terminal of the first comparator COM1 and the inverting side input terminal of the second comparator COM2 for comparison with the set reference voltage. Is done. Here, the setting reference value Vref1 of the first comparator COM1 corresponds to the first setting current value I1 in FIGS. 3A and 3B, and the setting reference voltage Vref2 of the second comparator COM2 It is configured to correspond to the second set current value I2 shown in 3 (B).

  Then, the comparison result outputs of the first and second comparators COM1 and COM2 are input to the first switch means SW1, and the switch terminals are switched.

  The first switch SW1 is provided with terminals from three types of voltage sources V1, V2, and V3 (assuming that V1 <V2 <V3), and the first and second comparators COM1, The output is switched based on the output of COM2. Normally, it is connected to the center V2 terminal.

  For example, when the output Vic from the current detection unit 4 is lower than the reference voltage Vref1 of the first comparator COM1, a switching control signal is output from the comparator COM1, and the switching terminal of the switching unit SW1 is changed from V2 to V1. Works like switching. Thus, the output of the first switch means SW1 switched to the voltage V1 side lower than the normal setting voltage is input to the main power supply 1 as the voltage Vin via the third switch means SW3, and the main power supply Side output current Is is controlled to decrease. In this way, the load on the auxiliary power supply is increased.

  On the other hand, when the output Vic from the current detection means 4 is higher than the set reference voltage Vfer2 of the second comparator COM2, a switching control signal is output from the comparator COM2, and based on this, the switching control signal of the first switch means SW1 is output. When switched to the high voltage terminal V3 side and input as the input voltage Vin to the main power supply 1 via the first switch means SW3, the output current Is of the main power supply is increased to reduce the burden on the auxiliary power supply. Work like so.

(Voltage detection operation)
Next, the process of the output from the voltage detection means arrange | positioned above FIG. 7 is demonstrated. In this case, the third switch means SW3 can be switched to the output side of the second switch means SW2 by an external switching signal.

When the output Vh of the voltage detection means 5 is lower than the set reference voltage value Vref3 (corresponding to the third set value in FIG. 4) of the third comparator COM3, the second switch means based on the output The set voltage terminal of SW2 is switched from V4 to V5 (V4 <V5) and sent to the main power supply 1 as the control voltage Vin via the third switch means SW3. As a result, the output current Is of the main power source is controlled to increase, thereby reducing the burden on the auxiliary power source.
As described above, the current supplied to the load is shared and controlled between the main power supply and the auxiliary power supply.

  The control based on the current detection and the control based on the voltage detection are selected by an external switching signal for switching the third switch means SW3. This selection criterion is, for example, an operating environment in which the load periodically reaches a peak. Then, it is preferable to select the current detection control and arbitrarily switch the voltage detection control so that the voltage detection control is selected in an environment in which the load instantaneously reaches the peak (when the instantaneous current flows).

FIG. 8 shows an image forming system provided with the power supply apparatus.
As shown in the figure, an image forming apparatus 10 having a DC power source 10A is combined with a post-processing device (for example, finisher) 11. The post-processing device 11 includes the main power source 1, the auxiliary power source 3, and the control unit. A connection configuration between the means 6 and the load 2 is applied.
In such a system, the power supply device performs operations as shown in the flowcharts of FIGS. 5 and 6 to appropriately distribute the power supply between the main power supply and the auxiliary power supply, and the main power supply does not become overloaded. An image forming system capable of performing an image forming operation under such an operating environment is provided.

It is a schematic block diagram of a power supply device. It is a concrete block diagram of the control means in the said block diagram. It is a time chart for demonstrating electric current detection control operation. It is a time chart for demonstrating voltage detection control operation | movement. It is a flowchart for demonstrating electric current detection control operation. It is a flowchart for demonstrating voltage detection control operation | movement. It is a block diagram which shows the hardware constitutions of a control means. 1 is a block diagram showing an image forming system incorporating a power supply device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main power supply 2 Load 3 Auxiliary power supply 4 Current detection means 5 Voltage detection means 6 Control means 10 Image forming apparatus 11 Post-processing apparatus

Claims (6)

A main power source, an auxiliary power source composed of an electric double layer capacitor and a load are connected, and the main power source and the auxiliary power source are phase-shared to supply power to the load,
Output detection means for detecting the output of the auxiliary power supply, and power control means for controlling the value of the output current of the main power supply based on the detection output of the output detection means,
A power supply characterized by. The output detection means is current detection means for detecting an output current of the auxiliary power source,
The power control means decreases the output current value of the main power supply when the detection output from the current detection means is smaller than a first set value set in advance, or less than a second set value. If larger, control to increase the output current value of the main power supply,
The power supply device according to claim 1.   The output detection means is a voltage detection means for detecting an output voltage of the auxiliary power supply, and the power control means is configured to detect the main power when the output of the voltage detection means is lower than a preset third set value. The power supply apparatus according to claim 1, wherein control is performed so as to increase an output current value of the power supply.   A power supply device connected to a main power supply, an auxiliary power supply composed of an electric double layer capacitor, and a load, and supplying power to the load by sharing the main power supply and the auxiliary power supply. A current detection means for detecting an output current, a voltage detection means for detecting an output voltage of the auxiliary power supply, an output of the current detection means and a predetermined set value are compared, and the main power supply is determined according to the level of the set value. A current detection processing unit that outputs a control signal for reducing or increasing the output current of the main power supply is compared with the output of the voltage detection means and a preset set value. When the detected voltage is lower than the set value, A power detection means comprising a voltage detection processing section for outputting a control signal for increasing the output current; a switching means for switching the output of the current detection processing section and the voltage detection processing section; and a switching signal to the switching means. Power supply and having an input means for supplying.   When the internal impedance of the main power supply is Zm and the internal impedance of the auxiliary power supply is Zc, the current value supplied from the main power supply is Is (A) and the load peak current is ILpeak ( A) When the allowable voltage drop width of the auxiliary power supply is ΔVCAP (V), and the auxiliary power supply voltage drop width per cycle of the load current by supplying power from the auxiliary power supply to the load is ΔVL (V), Is ≧ 5. The power supply device according to claim 1, wherein a relationship of ILpeak− (ΔVCAP−ΔVL) / Zc is satisfied.   An image forming system in which the power supply device according to claim 1 is incorporated in a post-processing device of the image forming apparatus.

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