JP2014204532A - Power supply device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device including switching regulators and capable of accurately detecting power consumption of an electric apparatus.SOLUTION: An power supply device comprises: a detection unit for detecting signals which change in synchronization with switching operations of switching regulators; a storage unit for storing measurement data of the relation between AC power supplied to a measurement switching regulator of the same type of each switching regulator and a switching operation of the measurement switching regulator; and an estimation unit for estimating an amount of AC power inputted to the switching regulator on the basis of the measurement data and the signal detected by the detection unit in a state where DC power is outputted from the switching regulator to a load.

Description

  The present invention relates to a power supply device and an image forming apparatus having a switching regulator.

  In various electric devices that operate a DC load using a commercial AC power supply, a switching regulator is used to generate DC power. Commonly used insulating switching regulators include flyback type, forward type, and resonance type, and are used properly according to the load. Some electric devices include a plurality of switching regulators suitable for loads having different operating voltages, such as a control system and a drive system.

  Conventionally, an apparatus for indirectly measuring power consumption during operation of an electric device operated by a commercial AC power supply has been proposed. The power consumption measuring device described in Patent Document 1 calculates the turn-on time of the switching means based on the primary voltage of the transformer means in the switching regulator. Then, power consumption is calculated based on the calculated turn-on time, the switching frequency of the switching means, and the inductance of the transformer means.

JP 2004-101518 A

  In order to perform power control that suppresses the power consumption of an electrical device below a regulation value, or to perform a display that informs the user of the actual power consumption, it is necessary to measure the power consumption more accurately. In the case of an electric device equipped with a switching regulator, power loss occurs in the switching regulator. Therefore, it is necessary to measure not the power supplied from the switching regulator to the load but the power input from the AC power source to the switching regulator as the power consumption. is there.

  In the method of Patent Document 1, the power consumption is calculated based on a theoretical formula that holds when the power supply efficiency (conversion efficiency of the switching regulator) is constant. However, the actual power supply efficiency varies depending on the input power and load of the switching regulator. There are individual differences in power supply efficiency in mass production of switching regulators. Therefore, the calculated power consumption is not always accurate.

  In view of such circumstances, an object of the present invention is to provide an apparatus that more accurately detects the power consumption of an electrical device having a switching regulator.

  A device that achieves the above object is a power supply device having a switching regulator, which supplies a detection unit that detects a signal that changes in synchronization with the switching operation of the switching regulator, and a measurement switching regulator that is the same type as the switching regulator. Detected by the measurement data and the detection unit in a state where the measurement data of the relationship between the AC power to be measured and the switching operation of the measurement switching regulator is stored, and the DC power is output from the switching regulator to the load And an estimation unit that estimates the amount of AC power input to the switching regulator based on the signal.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to detect the power consumption of the electric equipment which has a switching regulator more correctly.

It is a figure which shows the schematic structure of the power supply device which concerns on embodiment of this invention. FIG. 3 is a circuit diagram of a main part of a first switching regulator. It is a figure which shows the circuit of the principal part of a 2nd switching regulator. 6 is a graph showing the relationship between the duty ratio of the switching operation and the input power in the first switching regulator. 6 is a graph showing a relationship between a duty ratio of switching operation and input power and a relationship between a switching frequency and input power in the first switching regulator. It is a graph which shows the relationship between the switching frequency of switching operation in a 2nd switching regulator, and input electric power. It is a figure which shows the example of the apparatus for measuring the relationship between duty ratio and input electric power, and the relationship between switching frequency and input electric power. It is a figure which shows the function structure of the principal part of a power supply device. It is a figure which shows the data structure of the actual measurement table corresponding to a 1st switching regulator. It is a figure which shows the data structure of the actual measurement table corresponding to a 2nd switching regulator. It is a figure which shows the individual difference of the relationship between switching frequency and input electric power. 6 is a flowchart of a measurement process for the first switching regulator. 1 is a diagram illustrating a configuration of an image forming apparatus including a power supply device. It is a graph which shows the input voltage dependence of the relationship between duty ratio and input electric power. It is a figure which shows the other structure of a power supply device.

  A power supply device 2 illustrated in FIG. 1 includes a power supply circuit 3 and a control circuit 7 incorporated in the image forming apparatus 1 that prints an image. The power supply circuit 3 includes a power factor correction circuit (PFC) 4 including a rectifier circuit and two switching regulators 5 and 6. The AC power supplied from the commercial AC power supply 9 is converted into DC power by the power supply circuit 2 and supplied to the control circuit 7 that controls the operation of the image forming apparatus 1 and the drive mechanism 8 having other DC loads such as a motor and a solenoid. The The image forming apparatus 1 has a fixing heater 310 as an AC load. AC power is supplied to the heater 310 without going through the power factor correction circuit 4.

  One switching regulator 5 of the power supply circuit 3 is a flyback type, and supplies DC power of, for example, 12 volts to the control circuit 7. The other switching regulator 6 is a current resonance type, and supplies DC power of, for example, 24 volts to the drive mechanism 8. Electric power is input to the switching regulators 5 and 6 from the power factor correction circuit 4.

  The control circuit 7 measures the power input to the switching regulators 5 and 6 as described later. Therefore, signals S5 and S6 that change in synchronization with the switching operation are input to the control circuit 7 from the switching regulators 5 and 6, respectively. The control circuit 7 adds the measured input power of the two switching regulators 5 and 6 and adjusts the power consumption by the heater 310 according to the added value. That is, control is performed to distribute more power from the commercial AC power supply 9 to the AC load within a range where the power consumption of the entire image forming apparatus 1 does not exceed a specified value (for example, 1500 W).

  In order for the image forming apparatus 1 to perform printing at the maximum specification speed, it is necessary to supply sufficient power to the fixing heater 310. When the power that can be supplied is insufficient, the distance between sheets in the continuous conveyance of the sheet must be increased, and the number of printed sheets per unit time decreases (productivity decreases). Moreover, the heating time until printing at a low temperature becomes possible becomes longer.

  By measuring the actual power consumption of the DC load including the control circuit 7, the remaining power obtained by subtracting the power consumption of the DC load from the rated power of the image forming apparatus 1, that is, surplus power is allocated to the heater 310 to the maximum. be able to. On the other hand, when the actual power consumption of the DC load is not measured, the power that can be distributed to the heater 310 is the remaining power obtained by subtracting the maximum power consumption determined by the DC load specifications from the rated power of the image forming apparatus 1. Become. In order to distribute more power to the heater 310, it is necessary to more accurately measure the actual power consumption of the DC load. Although not shown, the image forming apparatus 1 is provided with a controller that controls the heater 310.

  As shown in FIG. 2, the switching regulator 5 includes a transformer (converter transformer) 51, a FET (Field Effect Transistor) 52 as a switching element, a primary smoothing capacitor 53, a secondary smoothing capacitor 55, and a rectifying diode. 54. A switching control circuit (not shown) controls on / off of the FET 52 to interrupt the current flowing through the primary side coil of the transformer 51. When the FET 52 is switched from on to off, a current flows through the secondary coil of the transformer 51 by mutual induction, and the capacitor 55 is charged. The switching control circuit monitors the voltage across the capacitor 55 and controls the FET 52 so as to keep the voltage across the capacitor at a predetermined value (for example, 12 volts).

  In this example, the signal S5 appearing at the connection point P1 between the secondary coil of the transformer 51 and the anode of the diode 54 is used to measure the power input to the switching regulator 5. The control circuit 7 detects the on / off duty ratio and switching frequency of the FET 52 based on the signal S5.

  As shown in FIG. 3, the switching regulator 6 includes a transformer 61, a resonant capacitor 62, a pair of transistors 63 and 64 as switching elements, a primary smoothing capacitor 65, a secondary smoothing capacitor 66, and a rectifying diode 67. , 68. A switching control circuit (not shown) performs on / off control of the transistors 63 and 64 according to the output fluctuation of the transformer so that the switching frequency and the resonance frequency coincide with each other.

  In this example, the signal S6 appearing at the connection point P2 between the secondary coil of the transformer 61 and the anode of the diode 67 is used to measure the power input to the switching regulator 6. The switching frequency of the transistors 63 and 64 is detected by the control circuit 7 based on the signal S6.

  The graph of FIG. 4 shows the relationship between the duty ratio of the switching operation and the input power in the flyback type switching regulator 5. When the output current on the horizontal axis increases, that is, when the load increases, the input power increases. The output current and input power are almost proportional. In the switching operation for keeping the output voltage of the switching regulator 5 constant, there is a correlation as shown between the duty ratio (ratio of the ON period to the ON edge interval of the FET 52) and the input power. Therefore, if this correlation is measured and stored in advance, the input power (that is, the actual power consumption of the control circuit 7) can be obtained from this correlation by detecting the duty ratio during operation. For example, if the duty ratio is 10.55%, the output current is 2 A, and the input power at that time is 13.34 W.

  The graph of FIG. 5 shows the relationship between the duty ratio of the switching operation and the input power and the relationship between the switching frequency and the input power in the flyback type switching regulator 5. The relationship between the duty ratio and the input power is the same as in FIG.

  In the switching regulator 5, the switching frequency is changed according to the load. In the light load region LL where the output current is 2.6 A or less, the switching frequency and the input power are almost proportional. However, in the middle load region LM and heavy load region LH where the output current exceeds 2.6 A, the switching frequency is maintained at 60 kHz regardless of the load size. Therefore, for the light load region LL, the input power can be obtained by detecting the duty ratio or the switching frequency. For the medium load range LM and the heavy load range LH, the input power can be obtained by detecting the duty ratio.

  For a load range (power range) where the change in duty ratio is small, such as a heavy load region LH where the output current exceeds 6A, the input power can be obtained more accurately by increasing the resolution of detecting the duty ratio. Can do. Specifically, the duty ratio change width when the output current changes from 5.6 A to 5.7 A is about 0.31%, but the duty ratio when the output current changes from 6.7 A to 6.8 A. The range of change in the ratio is only 0.03%. Therefore, the control circuit 7 performs detection by raising the resolution 10 times or more. For example, the signal S5 is amplified 10 times before A / D conversion.

  The graph of FIG. 6 shows the relationship between the switching frequency of the switching operation and the input power in the current resonance type switching regulator 6. As the output current on the horizontal axis increases, the input power increases. The output current and input power are almost proportional. In the current resonance type, when the switching frequency is lowered, the output current increases, and the input power increases accordingly. If the relationship between the switching frequency and the input power is measured and stored, the input power (that is, the actual power consumption of the drive mechanism 8) can be obtained by detecting the switching frequency during operation. For example, in the illustrated example, when the switching frequency is 135 kHz, the input power is 82.4 W.

  FIG. 7 shows an example of an apparatus for actually measuring the relationship between the duty ratio and the input power and the relationship between the switching frequency and the input power. For example, when the relationship between the duty ratio and the input power is actually measured, a wattmeter 90 is inserted between the power supply circuit 3A including the measurement switching regulator 5A of the same type as the switching regulator 5 and the commercial AC power supply 9 for measurement. An electronic load 91 with variable current is connected to the switching regulator 5A. Each time the current flowing through the electronic load 91 is switched, for example, in increments of 0.1 A, the wattmeter 90 measures the amount of power input to the switching regulator 5A, and the oscilloscope 92 is used to measure the duty ratio from the waveform of the signal S5. . Further, the switching frequency is measured by the oscilloscope 92 or the frequency counter 93. Similarly for the switching regulator 6, the electronic load 91 can be connected to the switching regulator 6 or a measurement switching regulator of the same type to measure the relationship between the switching frequency and the input power.

  FIG. 8 shows a functional configuration of a main part of the power supply device 2. The control circuit 7 includes a central processing unit (CPU) 71 as a computer that executes a control program, a random access memory (RAM) 72 that is used as a work area for program execution, and a nonvolatile memory as a storage unit 73. .

  The CPU 71 includes a duty ratio detection unit 101, two frequency detection units 102 and 104, an estimation unit 105, and a power supply control unit 106. These elements are functional elements realized by the CPU 71 executing a predetermined program.

  The duty ratio detection unit 101 detects the duty ratio in the switching operation of the switching regulator 5 based on the signal S5 input from the switching regulator 5 to the A / D conversion port of the CPU 71. For example, the signal S5 is sampled at a predetermined period, the number of samplings corresponding to the on period and the off period are counted, and the ratio of the number of samplings corresponding to the on period to the sum of both sampling numbers is calculated. The duty ratio detection unit 101 switches the detection resolution as needed by adjusting the gain of the input amplification unit.

  The frequency detector 102 detects the switching frequency of the switching regulator 5 based on the signal S5. That is, the switching cycle is detected and the reciprocal thereof is calculated. The frequency detection unit 104 detects the switching frequency in the switching operation of the switching regulator 6 based on the signal S5 input from the switching regulator 6 to the A / D conversion port of the CPU 71.

  The estimation unit 105 calculates the power consumption of the control circuit 7 and the drive mechanism 8 with reference to the actual measurement tables T5 and T6 and the individual difference correction data D5 and D6 stored in the storage unit 73. Here, the actual measurement table T5 stores actual measurement data on the relationship between the AC power supplied to the measurement switching regulator of the same type as the switching regulator 5 and the switching operation of the measurement switching regulator. The actual measurement table T6 stores actual measurement data on the relationship between the AC power supplied to the measurement switching regulator of the same type as the switching regulator 6 and the switching operation of the measurement switching regulator.

  The estimation unit 105 reads the input power amount corresponding to the duty ratio detected by the duty ratio detection unit 101 or the switching frequency detected by the frequency detection unit 102 from the actual measurement table T5. If there is no duty ratio or switching frequency in the actual measurement table T5 that exactly matches the detected duty ratio or switching frequency, it is based on the input power amount associated with a plurality of values close to the detected duty ratio or switching frequency. Input power is calculated by interpolation. Then, the input power amount obtained by the actual measurement table T5 is corrected based on the individual difference correction data D5 indicating the individual difference between the switching regulator 5 and the measurement switching regulator, and the corrected input power amount is actually changed. This is an estimated amount of input power.

  Similarly, for the switching regulator 6, the estimation unit 105 specifies the input power amount corresponding to the switching frequency detected by the frequency detection unit 104 using the actual measurement table T 6 and corrects it based on the individual difference correction data D 5. Then, the corrected input power amount is set as an estimated amount of the actual input power amount.

  Subsequently, the estimation unit 105 calculates the total amount of input power estimated for the switching regulator 5 and the switching regulator 6, and notifies the power supply control unit 106 of the calculation result as power consumption of the DC system.

  The power supply control unit 106 distributes AC power to the fixing device 30 so that the overall power consumption of the image forming apparatus 1 does not exceed the rated power, according to the power consumption of the DC system notified from the estimation unit 105.

  As shown in FIG. 9, in the actual measurement table T <b> 5, input power is stored in association with the duty ratio and the switching frequency that are actually measured using a measurement switching regulator of the same type as the switching regulator 5. Further, as shown in FIG. 10, in the actual measurement table T <b> 6, input power is stored in association with the actual switching frequency using a measurement switching regulator of the same type as the switching regulator 6.

  FIG. 11 shows individual differences in the relationship between the switching frequency and the input power. Even with the same type, there are some individual differences in switching regulators that are mass-produced. Therefore, when the actual measurement tables T5 and T6 are created, data indicating the average characteristics of the switching characteristics actually measured using a plurality of measurement switching regulators of the same type may be stored.

  When one of the mass-produced products of the switching regulator 5 and one of the mass-produced products of the switching regulator 6 are incorporated into the image forming apparatus 1, individual differences between the incorporated switching regulators 5 and 6 and the measurement switching regulator are examined, and individual differences are corrected. Data D5 and D6 are created. With respect to the switching regulators 5 and 6 to be incorporated, the switching characteristics can be simply measured by using the apparatus shown in FIG. 7 and the number of parameter switching is about several, and individual differences from the measurement switching regulator can be obtained.

  Instead of using the individual difference correction data D5 and D6, the switching characteristics of the switching regulators 5 and 6 themselves incorporated in the image forming apparatus 1 are precisely measured, and data indicating the results are stored in the actual measurement tables T5 and T6. May be.

  FIG. 12 is a flowchart of measurement processing for the flyback type switching regulator 5. As described above, with respect to the switching regulator 5, the input power is estimated by selectively detecting the duty ratio and the switching frequency according to the increase or decrease of the load. Further, in the heavy load region LH, the detection resolution is made higher than those in the light load region LL and the medium load region LM.

  First, the measurement mode is initialized (S10). At this time, the duty ratio detection mode is set, and the resolution is set to the normal resolution. The input power is indirectly measured (estimated) in the initially set mode, and it is checked whether the measurement result corresponds to the light load region LL, the medium load region LM, or the heavy load region LH (S11, S12). . If the measurement result is the medium load range LM, the flow returns to step S10. In this case, the input power is measured again in the initially set measurement mode. If the measurement result is a light load range LL, the mode is switched to a measurement mode for detecting the switching frequency (S13), and if the measurement result is a heavy load range LH, the mode is switched to a measurement mode for detecting the duty ratio with high resolution ( S14).

  FIG. 13 shows the configuration of the image forming apparatus 1. The image forming apparatus 1 is a tandem color printer that forms a color image or a monochrome image by electrophotography. Since four color toner images of yellow (Y), magenta (M), cyan (C), and black (K) are formed in parallel when forming a color image, the image forming apparatus 1 includes an intermediate transfer belt 20 and an intermediate transfer belt. There are four process units UY, UM, UC, UK arranged along the belt 20. The process unit UK for forming a black (K) image includes a photosensitive drum 11, a charging device 12, a print head 13, a developing device 14, a primary transfer device 15, and a cleaning device 16, and other process units. UY, UM, and UC also have similar components except for the difference in toner colors. A lamp heating type fixing device 30 is mounted on the image forming apparatus 1. The fixing device 30 includes a fixing roller (heating roller) 31 and a pressure roller 32. A heater 310 as a heat source for raising the temperature of the surface of the fixing roller 31 is a halogen lamp.

  When, for example, a color print job is given to the image forming apparatus 1 from an external device (not shown) (for example, a personal computer), the charging device 12 uniformly spreads the surface of the photosensitive drum 11 in the process units UY, UM, UC, UK. Charge. A light beam emitted from the print head 13 is controlled on and off in accordance with image data from an external device, and a latent image is formed on the surface of the photosensitive drum 11. The latent image is developed into a toner image by the developing device 14 and is primarily transferred to the intermediate transfer belt 20 by the primary transfer device 15. The toner images of the four colors are superimposed on the intermediate transfer belt 20 by primary transfer synchronized with the movement of the intermediate transfer belt 20. In parallel with the formation of the four-color toner images, the paper P of the type and size specified by the job is taken out from the paper storage unit 24, and the intermediate transfer belt 20 and the secondary transfer roller 27 are opposed to each other by the conveying roller 26. It is conveyed to the next transfer position. The sheet P on which the toner image is secondarily transferred from the intermediate transfer belt 20 passes through the fixing device 30 and is then discharged to the discharge tray 29 by the discharge roller pair 28. When the paper P passes through the fixing device 30, the toner is melted and the image is fixed on the recording paper.

  The graph of FIG. 14 shows the input voltage dependency of the relationship between the duty ratio and the input power. The power supply circuit 3 described above has a power factor correction circuit 4. However, in a single regulator type power supply circuit having only a flyback type switching regulator, the power factor correction circuit 4 is not essential, and a configuration without the power factor improvement circuit 4 is often adopted. Since the power factor improving circuit 4 is a boost converter system and boosts the input voltage to a constant voltage, when the power factor improving circuit 4 is provided, fluctuations in the input voltage do not affect the duty ratio of the switching operation of the switching regulator. On the other hand, when the power factor correction circuit 4 is not provided, the duty ratio varies depending on the input voltage as shown in FIG.

  Therefore, in a configuration in which the power factor correction circuit 4 is not mounted, it is necessary to detect the input voltage of the switching regulator. Correct the input power reading from the actual measurement table of the relationship between the duty ratio and input power at a specific input voltage according to the input voltage, or the relationship between the duty ratio measured using the input voltage as a parameter and the input power Are prepared as a table, and the input power corresponding to the detected duty ratio and input voltage is read from the table. There are two methods for detecting the input voltage: a method of directly reading by dividing a resistance voltage, and a method of using an arithmetic circuit for detection.

  When the method of correcting the reading of the actual measurement table is adopted, the input voltage at the actual measurement is set to 230 volts, for example. For example, when the detected duty ratio for the switching regulator having the characteristics as shown in FIG. 14 is 13.2% and the input voltage is 187 volts, 15.2 is obtained by dividing 13.2% by the correction coefficient 0.83. The input power corresponding to 9% may be read.

  FIG. 15 shows another configuration of the power supply device. The power supply device 2b includes a single switching regulator 5 and does not have a power factor correction circuit. The control circuit 7b has a CPU 71 and a storage unit 73b. The CPU 71b includes an estimation unit 105b and an input voltage detection unit 103, and the storage unit 73b stores an actual measurement table T5 and correction data (correction coefficient) D50 for changes in input voltage.

  The input voltage detector 103 captures the output of the detection circuit 83 that detects the input voltage of the switching regulator 5 and detects the input voltage. The estimation unit 105b estimates the input power from the detected duty ratio or switching frequency and the input voltage with reference to the actual measurement table T5 and the correction data D50.

  According to the above embodiment, since the signals S5 and S6 are obtained from the secondary side of the switching regulators 5 and 6 and the input power is indirectly measured, the insulating parts necessary for obtaining the signal from the primary side The input power can be measured without mounting. However, a signal that motivates the switching operation may be input to the control circuit 7 from the primary side of the transformers 51 and 61 using an insulating means such as a photocoupler or a pulse transformer.

  In the above-described embodiment, the configuration of the power supply device 2 including the circuit system and number of the switching regulators 5 and 6 can be changed as appropriate within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2, 2b Power supply device 5 Switching regulator (1st switching regulator)
6 Switching regulator (second switching regulator)
S5, S6 signal T5, T6 actual measurement table (actual measurement data)
73 Storage Unit 105, 105b Estimation Unit 101 Duty Ratio Detection Unit 102, 104 Frequency Detection Unit 103 Input Voltage Detection Unit 106 Power Supply Control Unit D50 Correction Data LL Light Load Range (Power Range)
LM medium load range (power range)
LH Heavy load range (power range)
30 Fixing device 7 Control circuit (DC load)
8 Drive mechanism (DC load)

Claims (8)

A power supply device having a switching regulator,
A detector that detects a signal that changes in synchronization with the switching operation of the switching regulator;
A storage unit for storing actual measurement data of the relationship between the AC power supplied to the measurement switching regulator of the same type as the switching regulator and the switching operation of the measurement switching regulator;
An estimation unit that estimates the amount of AC power input to the switching regulator based on the actual measurement data and the signal detected by the detection unit in a state where DC power is output from the switching regulator to a load. A power supply device comprising: The switching regulator is a flyback type,
The actual measurement data indicates the relationship between the duty ratio of the switching operation of the measurement switching regulator and the AC power supplied to the measurement switching regulator,
The power supply apparatus according to claim 1, wherein the estimation unit estimates the electric energy based on a duty ratio of the signal. A voltage detector for detecting an input voltage of the switching regulator;
The storage unit stores correction data indicating a relationship between an input voltage of the switching regulator for measurement and a duty ratio of a switching operation together with the actual measurement data,
The power supply apparatus according to claim 2, wherein the estimation unit estimates the power amount by correcting the actual measurement data based on the correction data in accordance with the input voltage detected by the voltage detection unit. The actual measurement data indicates the relationship between the duty ratio of the switching operation of the measurement switching regulator and the power, and the relationship between the switching frequency of the switching operation and the power,
The estimation unit estimates the power amount based on the frequency of the signal for a power amount range in which the frequency of the signal changes, and sets the duty ratio of the signal for the power amount range in which the frequency of the signal is constant. The power supply device according to claim 2, wherein the power amount is estimated based on the power amount. The switching regulator is a resonance type,
The actual measurement data indicates the relationship between the power and the switching frequency of the switching operation of the measurement switching regulator,
The power supply apparatus according to claim 1, wherein the estimation unit estimates the amount of power based on a frequency of the signal. The power supply device according to claim 1, wherein the detection unit detects a signal on a secondary side of a transformer included in the switching regulator as the signal. An image forming apparatus operated by power supplied from an AC power source,
A fuser that heats printing paper using AC power;
A switching regulator that converts AC power supplied from the AC power source into DC power;
DC load that consumes the DC power;
A detector that detects a signal that changes in synchronization with the switching operation of the switching regulator;
A storage unit for storing actual measurement data of the relationship between the AC power supplied to the measurement switching regulator of the same type as the switching regulator and the switching operation of the measurement switching regulator;
In the state where the DC power is output from the switching regulator to the DC load, the amount of AC power input to the switching regulator is estimated based on the measured data and the signal detected by the detection unit. An estimator to
An image forming apparatus comprising: a power supply control unit configured to increase or decrease power supplied to the fixing device in accordance with the estimated amount of power. The storage unit stores, together with the actual measurement data, individual difference correction data indicating a difference in switching operation characteristics between the switching regulator and the measurement switching regulator,
The image forming apparatus according to claim 7, wherein the estimation unit estimates the power amount by correcting the actual measurement data based on the individual difference correction data.

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