Method of calculating effective power relating to capacitor, method of measuring effective power consumed by capacitor, capacitor selection method, calculation apparatus for calculating effective power relating to capacitor, and recording medium storing the calculation program therefor

• US 20060142960A1
• Filed: 02/17/2006
• Published: 06/29/2006
• Est. Priority Date: 11/22/2002
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Yamada, Hirohisa, Kubota, Kazuyuki, Yamaoka, Osamu
• Granted Patent: US 7,409,304 B2
• Time in Patent Office: Days
• US Class Current: 702/60
• CPC Class Codes: G01R 21/1331 Measuring real or reactive component, measuring apparent energy

Abstract

In a method of calculating effective power relating to a capacitor, the waveform of a periodic voltage applied to a capacitor is set. The capacitance of a desired capacitor is input. The waveform of the periodic voltage applied to both ends of the capacitor is subjected to Fourier expansion. More specifically, the periodic voltage is Fourier-expanded in terms of sine and cosine-wave series of high-order frequency components. Further, an effective power consumed by the capacitor is calculated using data regarding temperature characteristics, voltage characteristics and a frequency characteristic of the capacitance and dielectric tangent of the capacitor.

Claims

1. A calculation apparatus for calculating effective power relating to a capacitor, excluding a battery, comprising a calculator programmed to:

store data on a plurality of capacitors, which do not include batteries, including capacitances and dielectric tangents thereof which are determined based on a voltage characteristic, a frequency characteristic, and a temperature characteristic of the capacitors, and data on a first effective power for each of a plurality of equilibrium temperatures of the plurality of capacitors;

when a predetermined capacitance required for an electric circuit using one of the capacitors and a waveform of a periodic voltage applied to both ends of said one of the capacitors are input, calculate a second effective power at each of a plurality of provisional temperatures from the input waveform of the periodic voltage;

determine as a target equilibrium temperature of the capacitor a temperature at which the first effective power is approximately equal to the second effective power;

determine as a target effective power corresponding to the periodic voltage the first effective power and the second effective power corresponding to the target equilibrium temperature; and

compare a stored allowable power of said one of the capacitors with the target effective power corresponding to the periodic voltage in order to determine whether or not said one of the capacitors is suitable for use in the electric circuit.

2. The calculation apparatus according to claim 1, wherein the calculator is programmed to:

perform Fourier expansion for the periodic voltage;

calculate effective power for each of a plurality of harmonics; and

determine the sum of the calculated effective powers of the harmonics as the second effective power corresponding to the periodic voltage, when the second effective power is calculated at each of the plurality of provisional temperatures.

3. A recording medium storing a program for performing a method of calculating effective power relating to a capacitor, excluding a battery, comprising the steps of:

storing data on a plurality of capacitors, which do not include batteries, including capacitances and dielectric tangents thereof which are determined based on a voltage characteristic, a frequency characteristic, and a temperature characteristic of the capacitors, and data on a first effective power for each of a plurality of equilibrium temperatures of the plurality of capacitors;

when a predetermined capacitance required for an electric circuit using one of the capacitors and a waveform of a periodic voltage applied to both ends of said one of the capacitors are input, calculating a second effective power at each of a plurality of provisional temperatures from the input waveform of the periodic voltage;

determining as a target equilibrium temperature of the capacitor a temperature at which the first effective power is approximately equal to the second effective power;

determining as a target effective power corresponding to the periodic voltage the first effective power and the second effective power corresponding to the target equilibrium temperature; and

comparing a stored allowable power of said one of the capacitors with the target effective power corresponding to the periodic voltage in order to determine whether or not said one of the capacitors is suitable for use in the electric circuit.

4. The recording medium according to claim 3, wherein the step of calculating the second effective power comprises the steps of:

performing Fourier expansion for the periodic voltage;

calculating effective power for each of a plurality of harmonics; and

determining the sum of the calculated effective powers of the harmonics as the second effective power corresponding to the periodic voltage.

5. A method of calculating effective power relating to a capacitor, excluding a battery, comprising the steps of:

storing data on a plurality of capacitors, which do not include batteries, including capacitances and dielectric tangents thereof which are determined based on a voltage characteristic, a frequency characteristic, and a temperature characteristic of the capacitors, and data on a first effective power for each of a plurality of equilibrium temperatures of the plurality of capacitors;

when a predetermined capacitance required for an electric circuit using one of the capacitors and a waveform of a periodic voltage applied to both ends of said one of the capacitors are input, calculating a second effective power at each of a plurality of provisional temperatures from the input waveform of the periodic voltage;

determining as a target equilibrium temperature of the capacitor a temperature at which the first effective power is approximately equal to the second effective power;

determining as a target effective power corresponding to the periodic voltage the first effective power and the second effective power corresponding to the target equilibrium temperature; and

comparing a stored allowable power of said one of the capacitors with the target effective power corresponding to the periodic voltage in order to determine whether or not said one of the capacitors is suitable for use in the electric circuit.

6. The method of calculating effective power relating to a capacitor according to claim 5, wherein the step of calculating the second effective power comprises the steps of:

performing Fourier expansion for the periodic voltage;

calculating effective power for each of a plurality of harmonics; and

determining the sum of the calculated effective powers of the harmonics as the second effective power corresponding to the periodic voltage.