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REVIEWS

Fujitsu General, Ld.

Fujitsu General, Ltd. Chooses the WT1600 Digital Power Meter and SignalExplorer DL7100

We are working on developing control technologies for home electronics, mainly air conditioner motors.
One of the important keys to producing reduced-energy consumer appliances is to decrease the power consumption of the motors and inverters. To evaluate power consumption, we use the WT1600 Digital Power Meter.

The reason we chose the WT1600 was its ability to analyze harmonics of waveforms input from motors or inverters.
Especially since the voltage and current waveforms input from motors tend to be quite distorted, each frequency component must be analyzed. Therefore we need an oscilloscope to monitor waveforms, and an FFT analyzer to measure the voltage and current of each frequency component. The WT1600 can accept simultaneous voltage and current input on 6 channels, and easily perform multichannel measurement of voltage and current at each frequency component, all in one unit.

Fujitsu General, Ltd.
Development Division 2,
Development Technology Group,
Mr. Masanori Mukami

The WT has a wide frequency bandwidth of 0.5 Hz to 1 MHz, so it's capable of measuring even distorted waveforms at high accuracy. Furthermore, a single WT can compute motor and inverter I/O efficiency, so it's extremely useful for evaluating decreases in power consumption.
With normal measurement, dispersion often occurs in instantaneous data, so we use the averaging function with its wide range of adjustability to obtain the average characteristics. Also, the data update rate can reach 50 ms (20 times per second), so we can load data that fluctuates at both slow and fast intervals.
The WT has a variety of display functions-from simultaneous display of numeric and waveform data to bar and vector graphs for watching the frequency-and the displays are in color which makes them really easy to read.

Our group worked on the
motor for the Nocria

To evaluate whether the motor control is working as designed, we have to be able to observe digital and analog signals simultaneously.
The DL7100 SignalExplorer digital oscilloscope has 4 channels of analog input and 16 bit logic input in one unit, so it's very efficient for simultaneous measurement. One of the main reasons we chose it was because of its sampling rate of 1 GS/s, and its high display update rate.

ACNocria TM
Products by Fujitsu General

Visit the Fujitsu General Web site.

Nagoya Institute of Technology

Nagoya Institute of Technology Chooses the WT1600 Digital Power Meter.

We do development for power electronics research in the Matsui laboratory. Our work can be broken down into three broad categories. The first is research on power conversion technology. For example, when power supplies of PC convert AC to DC inside, they generate harmonics.
These harmonics return to electric power systems coming from power plants, and can cause malfunctions and overheating. Guaranteeing that these harmonics can be controlled is one of our main objectives in the quest to deliver extremely stable and high quality electricity to users.

Nagoya Institute of Technology
Dept. of Electric & Computer Engineering
Mr.Takashi Kosaka, Dr. Eng. (right)
Mr. Shingo Fubuki,
Sophomore at the Graduate School (left)

The second is research on motion control. For example, when controlling items such as machine tools, since there is non-linear friction and other phenomena from non-linear elements, those elements drag down the accuracy of the control. To achieve high quality manufacturing process technology, we have to conquer the main causes of those problems, and make sure we can achieve the most important thing which is free, fast, and accurate control.

The third is research on AC motor drives. AC motor drives are currently used in various fields, and the requirements for motors are diversifying. Since there are totally different requirements for each of the different uses, it's important to design the best possible motor for the particular application. For that reason, we are developing CAD systems for Applications Specific Electric Motor drive (ASEM).
And among the various AC motors, we're focusing our attention on synchronized motors which are more efficient. However, since a rotor position sensor is generally necessary, we are developing sensor-less technology to fill the requirements of certain applications.

The motivation for bringing in the WT1600 Digital Power Meter for our motor drive research was to use a power meter that was able to analyze motor characteristics and thereby precisely measure whether values that were evaluated beforehand were actually correct.
In recent years, semiconductor power conversion technology (PWM technology) has been widely used for supplying power to motors. The WT1600's high, 1 MHz frequency bandwidth means we can expect highly accurate power measurement for PWM. Also, while viewing the waveform display, trend display, or vector display, we can measure various power parameters simultaneously which is a definite plus. It comes with a 50 A input element so large currents are also supported.

In R&D on ASEM CAD system, we also use the WT1600. We measure the voltage, current, and power on the inverter input and the motor input. Before bringing in the WT1600 we needed an additional digital oscilloscope, but now we can take measurements with just this 1 unit. That's one of it's biggest merits we think. We can view not only numeric data, but also simultaneously view waveforms of the input signals, so we don't have to use a waveform observation instrument such as an oscilloscope; that makes it tremendously efficient. The built-in printer and the ability to save to floppy disk make it easy to generate reports, so we plan to use it even more from here on out. The WT1600 we purchased has the motor evaluation option installed so in the future we will use it to measure the voltage output from torque-meter, and we plan to implement it for efficiency evaluation as well.