JPH0261573A - Correction of parasitic capacitance or the like in iron loss measuring system - Google Patents

Abstract

PURPOSE:To obtain a true induced voltage value by correcting a measuring data shown on a measuring device by a parasitic capacitance data stored. CONSTITUTION:When measuring an iron loss, values of parasitic capacitances or the like of an impedance of a cable and a jig are measured to be stored into a storage means. Then, actually, a magnetic core to be measured is excited to detect a voltage drop of a shunt device due to a secondary side induced voltage and a primary side excited current and a data obtained is corrected to a true value using the data stored previously. This enables measurement of a correct iron loss by determining true values of the secondary side induced voltage and the primary side excited current irrespective to the length of a cable for detection and up to a high frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for correcting parasitic capacitance, etc. in an iron loss measurement system that measures iron loss of a magnetic core.

(Prior art) Conventionally, as shown in Fig. 3, iron loss measurement systems have
A voltage is applied to the primary winding 2 which is wound around the magnetic core l to excite the magnetic core l, and a current detection resistor 3 is connected in series to the primary winding.
When a primary current is passed through, the secondary induced voltage Es induced in the secondary winding 4 wound around the magnetic core 1, the primary current ■, and the voltage drop of the current detection resistor 3 ■, ・R3 and coaxial cable 4
The voltage drops of a and 4b are separately supplied to the measuring device 6, and the secondary induced voltage E1 and the voltage drop! , ·Rs to measure the iron loss of the magnetic core 1. Here,■,
represents the primary current value, and Rs represents the impedance exhibited by the current detection resistor 3. In other words, the iron loss is...
(1) Calculated as follows. Here, Nl is the number of turns ε of the primary winding, N
2 represents the number of turns ε of the secondary winding, and Vo represents the volume of the magnetic core.

However, when transmitting the detected voltage signal to the measuring instrument 6, if the frequency is very high or the transmission cable is long, the magnitude and phase of the voltage signal may change due to the parasitic capacitance of the jig, cable, etc. However, an error occurs in the obtained iron loss value.

Conventionally, in order to reduce this error as much as possible, the length of the cable was shortened, or the measurement frequency was also reduced, for example, to several MHz.
Efforts have been made to keep z low. For this reason, when it is necessary to put a sample in a thermostatic oven or the like, there are inconveniences such as increasing the length of the cable, increasing errors, or forcing the frequency to be lowered by at least one order of magnitude.

(Problem to be Solved by the Invention) The present invention has been made to overcome the above-mentioned disadvantages, and when measuring iron loss, the impedance of the cable is measured using a jig even when the cable is quite long. Measure the values of parasitic capacitance, etc. of Then, the obtained data is corrected to the true value using previously stored data.

Therefore, for example, even if a constant temperature bath salt cable is connected, sufficient measurement accuracy can be obtained, and there is no need to suppress the upper limit frequency of measurement to be so low.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a method for controlling the induced voltage of a secondary winding wound around a magnetic core as a magnetic body to be measured for iron loss, and for exciting the magnetic core. In an iron loss measurement system that calculates the iron loss of the magnetic core by measuring the voltage drop caused by the excitation current detection resistor connected in series with the primary winding wound around the magnetic core, Parasitic capacitance data and/or impedance data possessed by at least one of the equipment, wiring, signal transmission cable, measuring instrument, etc. is obtained and stored in advance in a storage means, and the measurement data shown on the measuring instrument is stored in the storage means. The method is characterized in that the true induced voltage or current value for the sample or the like is obtained by correcting the parasitic capacitance data and/or impedance data.

(Embodiments) Next, preferred embodiments of a method for correcting parasitic capacitance and the like in the iron loss measurement system according to the present invention will be described in detail with reference to the accompanying drawings.

(1) Regarding correction of the influence of cable impedance and parasitic capacitance on signal transmission characteristics First, a method of correcting secondary induced voltage will be described. FIG. 1 shows a portion of FIG. 3 that is necessary for explaining the measurement of secondary induced voltage. In the figure. , no i,,, no. Since the characteristics of the cable and cable are known, these are input in advance as data into the storage section inside the measuring instrument. By adding the changes in the amplitude and phase of the signal obtained based on these manually inputted data to the measured value 9□, the true induced voltage t
2 can be easily obtained.

The same is true when transmitting the voltage drop of the shunt, ss is, and the true i can be easily determined.

(2) How to detect the true excitation current Figure 2 shows how the actual current flowing into the primary coil of the magnetic core 1 flows through each part. This shows whether the current I0 can be determined. Using the S%IS obtained in the previous section, ls can be obtained, but it is slightly different from the true excitation impedance. Therefore, by the following formula,
karano, seek.

In addition, in the above equation (5), the values in parentheses are as follows from FIG.

...(6) From this, it becomes as follows, and the true excitation current can be obtained as l0=aE2/. All of the above processes can be performed by manually inputting known impedance values into the storage section of the measuring device 6 in advance and calculating based on this data. Preferably, this calculation can be easily performed by a combi-secondary operator.

(3) Calculation of iron loss value Then, when the values of z and loO are determined by the above (1) and (2), the phase difference φ between the two is also determined, so the iron loss value W is calculated using the following formula % formula % It can be calculated immediately.

[Effects of the Invention] As described above, according to the present invention, the true values of the secondary induced voltage and the primary excitation current of the magnetic core to be measured can be determined regardless of the length of the detection cable and even in a high frequency band. This has the effect of making it possible to accurately measure iron loss.

Moreover, if a computer is used as the arithmetic device, it is easy to handle, and it is possible to quickly and accurately calculate values.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the circuit for the signal transmission path from the secondary winding to the measuring device when implementing the correction method according to the present invention, and Fig. 2 shows the iron loss value obtained using the correction method according to the present invention. Fig. 3 is a block diagram of iron loss measurement values according to the prior art.

Claims (2)

[Claims] (1) The induced voltage in the secondary winding wound around the magnetic core as the magnetic body to be measured for iron loss, and the excitation voltage connected in series to the primary winding wound around the magnetic core to excite the magnetic core. In an iron loss measurement system that calculates the iron loss of the magnetic core by measuring the voltage drop caused by a current detection resistor, at least one of the sample, jig, wiring, signal transmission cable, measuring instrument, etc. Parasitic capacitance data and/or
Alternatively, by obtaining impedance data and storing it in advance in a storage means, and correcting the measurement data shown on the measuring device with the stored parasitic capacitance data and/or impedance data, the true induced voltage or A method for correcting parasitic capacitance, etc. in an iron loss measurement system characterized by obtaining a current value. (2) In the method according to claim 1, the true value of the excitation current is determined by determining the excitation impedance of the magnetic core as the magnetic substance to be measured using parasitic capacitance data and/or impedance data obtained in advance of the sample, etc. A method for correcting parasitic capacitance, etc. in an iron loss measurement system, characterized in that: