Power estimating apparatus, image forming apparatus, and non-transitory computer readable medium

1. A power estimating apparatus comprising:

a control circuit configured to use an alternating-current power supply;

at least one converter that is connected to a branch point between the alternating-current power supply and the control circuit,

wherein the at least one converter includes a smoothing capacitor, and

wherein the at least one converter is configured to convert an alternating current from the alternating-current power supply into a direct current;

a detector configured to obtain a total amount of currents supplied to the control circuit and the at least one converter; and

at least one processor configured to implement an estimating unit configured to use the obtained total amount of currents to estimate an amount of the current supplied to the control circuit, the total amount of currents being obtained by the detector in a charge and discharge period during which the smoothing capacitor performs a charge and discharge operation.

2. The power estimating apparatus according to claim 1 , further comprising:

a voltage zero-cross detector configured to detect a zero cross of voltage supplied from the alternating-current power supply, and

wherein the at least one processor is configured to implement a specifying unit that specifies, as the charge and discharge period, at least one of a predetermined period before the zero cross and a predetermined period after the zero cross, the zero cross being detected by the voltage zero-cross detector.

3. The power estimating apparatus according to claim 2 , wherein the estimating unit is further configured to estimate an amount of the current supplied to the at least one converter to be equal to an amount obtained by subtracting an amount of the current supplied to the control circuit from the total amount of currents for a half current cycle or the total amount of currents for one current cycle, the half current cycle corresponding to a section of a pulse in which one zero cross of voltage supplied from the alternating-current power supply is detected, the one current cycle corresponding to a section of a pulse in which two zero crosses of the voltage are detected.

4. The power estimating apparatus according to claim 2 , wherein the at least one converter comprises a plurality of converters, and

wherein the estimating unit is configured to use the total amount of currents obtained by the detector in an overlapped charge and discharge period for smoothing capacitors of the plurality of converters so as to estimate the amount of the current supplied to the control circuit.

5. The power estimating apparatus according to claim 3 , wherein the at least one converter comprises a plurality of converters, and

wherein the estimating unit is configured to use the total amount of currents obtained by the detector in an overlapped charge and discharge period for smoothing capacitors of the plurality of converters so as to estimate the amount of the current supplied to the control circuit.

6. The power estimating apparatus according to claim 1 , wherein the estimating unit is further configured to estimate an amount of the current supplied to the at least one converter to be equal to an amount obtained by subtracting the estimated amount of the current supplied to the control circuit from the total amount of currents for a half current cycle or the total amount of currents for one current cycle, the half current cycle corresponding to a section of a pulse in which one zero cross of voltage supplied from the alternating-current power supply is detected, the one current cycle corresponding to a section of a pulse in which two zero crosses of the voltage are detected.

7. The power estimating apparatus according to claim 6 , wherein the at least one converter comprises a plurality of converters, and

wherein the estimating unit is configured to use the total amount of currents obtained by the detector in an overlapped charge and discharge period for smoothing capacitors of the plurality of converters so as to estimate the amount of the current supplied to the control circuit.

8. The power estimating apparatus according to claim 1 , wherein the at least one converter includes a plurality of converters, and

wherein the estimating unit is configured to use the total amount of currents obtained by the detector in an overlapped charge and discharge period for smoothing capacitors of the plurality of converters, so as to estimate the amount of the current supplied to the control circuit.

9. The power estimating apparatus according to claim 1 , wherein the control circuit comprises a fixing device control circuit.

10. The power estimating apparatus according to claim 1 , wherein the total amount of currents supplied to the control circuit and the at least one converter is a sum of the current supplied to the control circuit and the current supplied to the at least one converter.

11. The power estimating apparatus according to claim 1 , wherein the estimating unit is configured to use the obtained total amount of currents to estimate the amount of the current supplied to the control circuit alone.

12. The power estimating apparatus according to claim 1 , wherein the estimating unit is configured to use the obtained total amount of currents to estimate the amount of the current supplied to the control circuit and an amount of the current supplied to the at least one converter, using the detector, and without providing separate current detectors for each of the control circuit and the at least one converter.

13. The power estimating apparatus according to claim 1 , wherein the total amount of currents equals a sum of current A and current B,

wherein current A is current supplied to the control circuit, and

wherein current B is current supplied to the at least one converter that is different from current A.

14. An image forming apparatus comprising:

a driving circuit configured to use an alternating-current power supply to drive a fixing device comprising a heater, the fixing device being configured to fix a formed image;

a converter that is connected to a branch point between the alternating-current power supply and the driving circuit,

wherein the converter includes a smoothing capacitor, and

wherein the converter is configured to convert an alternating current from the alternating-current power supply into a direct current;

a detector configured to obtain a total amount of currents supplied to the driving circuit and the converter; and

at least one processor configured to implement an estimating unit configured to use the total amount of currents to estimate an amount of the current supplied to the driving unit, the total amount of currents being obtained by the detector in a charge and discharge period during which the smoothing capacitor performs a charge and discharge operation.

15. A power estimating apparatus comprising:

a control circuit configured to use an alternating-current power supply;

at least one converter that is connected to a branch point between the alternating-current power supply and the control circuit,

wherein the at least one converter is configured to convert an alternating current from the alternating-current power supply into a direct current;

a detector configured to obtain a total amount of currents supplied to the control circuit and the at least one converter; and

at least one processor configured to implement an estimating unit configured to estimate an amount of a current using the total amount of currents in at least one of a predetermined period before a zero cross and a predetermined period after the zero cross, the current being used when the control circuit operates, the zero cross being a zero cross of the total amount of currents obtained by the detector.

16. A non-transitory computer readable medium storing a program which, if executed, causes a computer to execute a process for power estimation, the process causing the computer to function as the estimating unit of the power estimating apparatus according to claim 1 .