JPH0758303B2 - Electronic load device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic load device.

[0002]

2. Description of the Related Art Conventionally, in the case of testing a power source or the like using an electronic load device, when it is desired to increase the load capacity economically, a plurality of electronic load devices having a relatively low capacity are shown in FIG. The method of connecting in parallel to the power source is generally used. In FIG. 5, reference numeral 51 is a power source for the test, and the electronic load devices 52 to 54 are connected by a bus line 55. The electronic load devices 52 to 54 are connected by the bus line 55 to the three electronic load devices 52 to 5
By configuring the bus line 55 so that one of the four becomes a master (master) and the other two become slaves (slave), the slave operates by following the operation of the master. This is for controlling all electronic load devices by a so-called master-slave system.

In the test circuit of the power source 51 constructed as shown in FIG. 5, the user operates the above-mentioned main machine to load current I flowing through the electronic load devices 52 to 54.
_{1 to} I ₃ can be controlled. Then, each of the electronic load devices 52 to 54 displays the values of the load currents I _{1 to} I ₃ flowing through the electronic load devices by an ammeter provided in each device.

[0004]

However, in the conventional electronic load device, since the ammeters provided in the respective devices respectively display the values of the load currents flowing through the individual devices, the entire electronic load device is displayed. Load current I supplied by the power supply 51
The value of must be obtained by the user by reading and adding the current value displayed by the ammeter of each of the electronic load devices 52 to 54. Therefore, the user has to read a plurality of ammeters, the user may misread the ammeter at this stage, and there is also a possibility that the calculation may be incorrect in the process of summing the current values. there were. Furthermore, it takes time to read a plurality of ammeters, and if the load current fluctuates within the reading time, there is a problem that an accurate value of the load current I cannot be obtained.

The above problems can be solved by providing an ammeter 56 for measuring the load current I. However, an ammeter with a large rated current value is relatively expensive. Therefore, when a power supply test device with a large load capacity is configured using such an ammeter, the cost will increase significantly as the load capacity increases, so the load capacity can be increased economically. You can't let it happen.

An object of the present invention is, when an electronic load device is connected in parallel to increase the load capacity, without using an ammeter 56 having a large rated current value, which is separate from the electronic load device, the power source to be tested. Is to provide an electronic load device capable of measuring the amount of load current supplied to the entire electronic load device and displaying the value.

[0007]

In order to achieve the above object, the present invention provides a load current detecting means for outputting a load current signal of an amount corresponding to a value of a load current input to an electronic load device, and an input terminal. Current signal adding means for supplying an added current signal to the output end by adding the amount of the current signal input to the load current signal and the amount of the load current signal, and the load current signal and the added current A current signal selecting means for inputting a signal and selecting and outputting one of the current signals, and measuring the amount of the current signal output from the current signal selecting means and displaying the current value corresponding to the amount. The present invention is characterized in that it is provided with a current measuring and displaying means.

[0008]

According to the present invention, the load current detecting means detects the value of the load current input to the electronic load device and outputs the load current signal. Then, a current signal having a value corresponding to the total value of the respective values of the load current input to the other electronic load device can be supplied to the input end. This current signal and the above-mentioned load current signal are added by the current signal adding means and output as an added current signal to the output end.

The current signal selection means selects the load current signal or the addition current signal and outputs it to the current measurement display means. The current measurement display means measures the input current signal and displays the current value corresponding to the amount of the current signal.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a load current measuring unit of an electronic load device according to an embodiment of the present invention.
In FIG. 1, the current detector 1 converts the amount of the load current I ₁ input to the electronic load device into a load current signal I _S1 having a voltage corresponding to the amount and outputs the load current signal I _S1 to the adder 2. The current detector 1 is usually composed of a resistor.

The adder 2 adds the current signal input from the input terminal 3 and the load current signal I _S1 and outputs the added current signal I _ST to the output terminal 4. As shown in FIG. 2, the adder 2 includes resistors 22 to 2 having the same resistance value as the operational amplifiers 20 and 21.
6 and outputs a voltage E ₁ + E ₂ obtained by adding the two input voltages E ₁ and E ₂ .

The switch 5 is supplied with the load current signal I _{S1 at} its terminal a and the addition current signal I _ST at its terminal b, and its common terminal is connected to the ammeter 6. The ammeter 6 measures the voltage of the current signal selected by the switch 5 and displays the value of the current corresponding to the voltage on the display 7. Here, in the present embodiment, the ammeter 6 and the display 7 constitute a multi-range digital ammeter.

The position detector 8 detects whether the common terminal of the switch 5 is connected to the terminal a or the terminal b and displays the result on the display 7. For example,
When the common terminal of the switch 5 is connected to the terminal a, the character "SLAVE" is displayed as shown in FIG.
When the common terminal is connected to the terminal b, FIG.
The character "MASTER" is displayed on the display 7 as shown in FIG.

In the present embodiment having the above-described structure, when the electronic load device is used alone, the common terminal of the switch 5 is used by connecting it to the terminal a. in this case,
Since the load current signal I _S1 having a voltage value corresponding to the amount of the load current I ₁ input to the electronic load device is supplied to the ammeter 6,
The display 7 displays the value of the load current I ₁ .

Next, the operation when the present embodiment is connected in parallel to the power source under test and used in the master-slave system will be described.

FIG. 4 is a diagram showing the connection relationship of the load current measuring units when three units of this embodiment are connected in parallel, and the same reference numerals as those in FIG. 1 denote the same components. The three electronic load devices 41 to 43 are connected by bus lines 44 and 45 so that the electronic load device 43 serves as a master machine and the electronic load devices 41 and 42 serve as slave machines. here,
Switch 5 of electronic load devices 41 and 42 that are slaves
Is connected to the terminal a, and the switch 5 of the electronic load device 43, which is the master machine, is connected to the terminal b. Therefore, the characters "SLAVE" are displayed on the indicators of the electronic load devices 41 and 42 as shown in FIG. 3 (A), and the indicator of the electronic load device 43 is shown in FIG. 3 (B). Like "M
The characters "ASTER" are displayed.

The signal lines 46 and 47 are signal lines for current signal communication. In an actual device, if one signal line is added to the conventional bus line for this current signal, the master-slave system is used. Connection between the electronic load devices can be easily performed.

The three electronic load devices 41 to 43 configured as described above are connected in parallel to the power source under test, and the electronic load devices 41 to 43 have load currents I _{1 to} I ₃ respectively.
Is flowing. In this case, in the electronic load devices 41 and 42 of the slave machine, since the switch 5 is connected to the terminal a, the value of the load current I ₁ is displayed on the indicator of the electronic load device 41 as the value of the electronic load device 42. The value of the load current I ₂ is displayed on the display.

Further, in the electronic load device 43 of the master machine, since the switch 5 is connected to the terminal b, 3
Addition current signal I _S1 + I corresponding to the total value I ₁ + I ₂ + I ₃ of the load currents supplied to the electronic load devices 41 to 43
_S2 + I _S3 is output from the adder 2 to the ammeter 6. Therefore, on the display of the electronic load device 43, the values of the load currents I ₁ + I ₂ + I ₃ supplied from the power source under test to the entire three electronic load devices 41 to 43 are shown in FIG. 3 (B). Like "M
It is displayed together with the characters "ASTER".

[0021]

As described above, according to the present invention, when the electronic load devices are connected in parallel to increase the load capacity, an ammeter having a large rated current value, which is separate from the electronic load device, is used. It is possible to measure the amount of load current supplied from the power source under test to the entire electronic load device without displaying the value and display the value.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a load current measuring unit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a configuration of an adder shown in FIG.

FIG. 3 is a diagram showing a display example on the display shown in FIG.

FIG. 4 is a diagram showing a connection relationship of load current measuring units when an embodiment of the present invention is connected in parallel.

FIG. 5 is a circuit configuration diagram when a conventional electronic load device is connected in parallel to test a power supply.

[Explanation of symbols]

 1 current detector 2 adder 3 input end 4 output end 5 switch 6 ammeter 7 indicator 8 position detector

Claims (2)

[Claims] 1. A load current detection means for outputting a load current signal of an amount corresponding to a value of a load current input to an electronic load device, an amount of a current signal input to an input end, and an amount of the load current signal. A current signal adding means for adding and forming an added current signal and supplying the added current signal to the output terminal, the load current signal and the added current signal are input, and one of the current signals is selected. An electronic load comprising: a current signal selection means for outputting; and a current measurement display means for measuring an amount of a current signal output from the current signal selection means and displaying a current value corresponding to the amount. apparatus. 2. A load current detection means for outputting a load current signal of an amount corresponding to a value of a load current input to an electronic load device, an amount of a current signal input to an input end, and an amount of the load current signal. A current signal adding means for adding and forming an added current signal and supplying the added current signal to the output terminal, the load current signal and the added current signal are input, and one of the current signals is selected. A current signal selecting unit for outputting, a selection result detecting unit for detecting a selection result of the current signal selecting unit, an amount of a current signal output from the current signal selecting unit, and a current value corresponding to the amount is measured. And a current measurement display means for displaying, according to the output of the selection result detecting means, which of the load current signal and the added current signal the current value is based on. Equipped An electronic load device characterized by the above.