JP6227613B2 - Overcurrent protection circuit and overcurrent protection method for error rate measuring apparatus - Google Patents

Description

  The present invention relates to an overcurrent detection circuit, an overcurrent protection circuit, an overcurrent detection method, and an overcurrent protection method for various measuring instruments such as an error rate measurement device and a spectrum analyzer.

  Conventionally, as an overcurrent detection device that detects that an overcurrent has flowed through the device, for example, a device disclosed in Patent Document 1 below is known.

  As shown in FIG. 2, the overcurrent detection device disclosed in Patent Document 1 includes a resistor 53 connected in series to a line 52 that supplies power to the device 51, and a reference voltage and resistance output by a reference voltage generation unit 54. The voltage of the resistor 53 is compared by the comparison means 55, and an alarm signal is generated when the voltage of the resistor 53 exceeds the reference voltage.

JP 02-106120 A

  By the way, in recent measuring instruments (for example, error rate measuring devices, spectrum analyzers, etc.), the power consumption of the entire device increases due to the increase in scale and performance, but the drive voltage of the device decreases with the development of semiconductor processes. It is coming. For this reason, the situation is that the influence of the voltage drop cannot be ignored.

  For this reason, it is desired to detect the overcurrent and protect the measuring instrument (device 51) from the overcurrent without using the (shunt) resistor 53 that causes a voltage drop as disclosed in Patent Document 1 described above. .

The present invention was made in view of the above problems, and detect an overcurrent without using a resistor to cause a voltage drop, error rate measurements can protect the error rate measuring device from overcurrent and its object is to provide an overcurrent protection times Michi及 beauty overcurrent protection method of the apparatus.

To achieve the above object, the overcurrent protection circuit of the error rate measuring apparatus according to claim 1 of the present invention, the power supply in accordance with the power source 2 to the load through the power supply line 4 are fed, to be measured In the overcurrent protection circuit of the error rate measurement device that measures the error rate when a test signal is input to an object ,
A potential difference detection unit 5 that detects a potential difference between two detection points for each power source type of power supplied to each load on the power supply line and outputs a potential difference signal;
The set number of times is set in advance for each power source type, and each potential difference signal input from the potential difference detection unit is multiplied by a predetermined conversion coefficient to be converted into a current value for each power source type. The converted current value for each power supply type is compared with a preset current for each power supply type set in advance, and any converted current value exceeds the set current corresponding to the power supply type of the current value , When the current value exceeding the set current exceeds the set number of times corresponding to the power source type of the current value, it is determined that there is an overcurrent, and the supply of power according to each load is shut off to An arithmetic processing unit 7 for protecting a load is provided.

The overcurrent protection circuit of the error rate measuring device according to claim 2 is the overcurrent protection circuit of the error rate measuring device of claim 1 ,
When it is determined that the overcurrent is present, a display unit 8 is provided for displaying the fact.

Overcurrent protection circuit of the error rate measuring apparatus according to claim 3, in the overcurrent protection circuit of the error rate measuring apparatus according to claim 1 or 2,
The power supply line 4 includes an AC-DC power supply device 4a connected to the power supply 2, and a DC-DC power supply circuit 4b connected between the AC-DC power supply device and each load. Features.

Overcurrent protection circuit of the error rate measuring apparatus according to claim 4, in the overcurrent protection circuit of any one of the error rate measuring apparatus according to claim 1 to 3,
A voltage detector 6 is provided for detecting the voltage of the power supplied to each load for each power source type.

The overcurrent protection circuit of the error rate measuring device according to claim 5 is the overcurrent protection circuit of the error rate measuring device according to any one of claims 1 to 4 ,
The line resistance remaining in the power supply line 4 is used as a current detection resistor.

The overcurrent protection method of the error rate measuring apparatus according to claim 6 is an error when a power supply corresponding to each load is supplied from the power supply 2 via the power supply line 4 and a test signal is input to the device under test. In the overcurrent protection method of the error rate measuring device for measuring the rate ,
Detecting a potential difference between two detection points for each power source type of power supplied to each load on the power supply line and outputting a potential difference signal;
Setting a set number of times for each power source type;
Each potential difference signal is multiplied by a predetermined conversion coefficient to be converted into a current value for each power supply type, and the converted current value for each power supply type and a preset current for each power supply type set in advance. Any of the converted current values exceeds the set current corresponding to the power type of the current value, and the current value exceeding the set current exceeds the set number of times corresponding to the power type of the current value. And determining that there is an overcurrent, and shutting off the supply of power according to each load to protect each load from the overcurrent .
Overcurrent protection method of the error rate measuring apparatus according to claim 7, in the overcurrent protection method of the error rate measuring apparatus according to claim 6,
When it is determined that the overcurrent is present, the method further includes a step of displaying the fact.
Overcurrent protection method of the error rate measuring apparatus according to claim 8, in the overcurrent protection method of the error rate measuring apparatus according to claim 6 or 7,
The step of using the line resistance remaining in the power supply line 4 as a current detection resistance is included.

According to the present invention, since the load current is detected using the power supply line as a current detection resistor, it is possible to detect an overcurrent without using a conventional resistor that causes a voltage drop. In addition, when the overcurrent is detected, the supply of power according to each load of the error rate measuring device is cut off, so that the error rate measuring device can be protected from the overcurrent.

It is a block diagram of an overcurrent protection circuit including an overcurrent detection circuit of a measuring instrument according to the present invention. It is a figure which shows an example of the conventional overcurrent detection circuit disclosed by patent document 1. FIG.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

The present invention, signals a large current flows in the tens amperes for high-speed processing, are employed in the error rate measuring equipment infusible difficulty inserting a shunt resistance, due to deterioration of the line resistance, overload or short ( Overcurrent protection circuit that protects the error rate measurement device (hereinafter referred to as measuring instrument) from overcurrent by detecting that an overcurrent has flowed through the error rate measurement device due to the occurrence of a power supply protection circuit not working And an overcurrent protection method.

  A measuring instrument in which the present invention is adopted has a configuration in which a plurality of measuring modules are detachably connected to a motherboard serving as a base substrate, for example. The measurement module in this example is equipped with a power supply module mounted with an AC-DC power supply device 4a described later, a DC-DC power supply circuit 4b, a potential difference detection unit 5, a circuit module mounted with a voltage detection unit 6, and an arithmetic processing unit 7. An arithmetic module, a measurement module on which the measurement unit 3 for measuring a device under test (DUT) is mounted, a display module on which the display unit 8 is mounted, and the like can be used. Measurement modules can be added as appropriate, and necessary measurement modules are connected to the motherboard according to the measurement contents of the object to be measured.

  As shown in FIG. 1, the overcurrent protection circuit 1 is connected to a power supply line 4 between a power source 2 and each load of the measuring instrument (in the example shown, the measurement unit 3), and is connected to a potential difference detection unit 5, a voltage A detection unit 6, an arithmetic processing unit 7, and a display unit 8 are provided.

  In FIG. 1, a solid line connecting each part indicates a power supply line, and a broken line connecting each part indicates a signal line or a control line. In the example of FIG. 1, the potential difference detection unit 5 and the voltage detection unit 6 constitute an overcurrent detection circuit.

  The power supply 2 is composed of, for example, a commercial power supply, and supplies AC 100V AC power to the power supply line 4 (AC-DC power supply device 4a of the power conversion unit 4A described later).

  The measurement unit 3 performs various measurements desired by the user using a DC power source supplied from the power source 2 via the power supply line 4 as a driving power source. For example, in the case of the measurement unit 3 of the error rate measuring apparatus, the error rate when a test signal (for example, a PRBS pattern) is input to the device under test is measured.

  The power supply line 4 is connected between the power source 2 and the measuring unit 3 of the measuring instrument, the peripheral circuit of the power source 2 and the measuring instrument (including the potential difference detecting unit 5, the voltage detecting unit 6, the arithmetic processing unit 7, and the display unit 8). Between the two. The power supply line 4 of this example includes, for example, a power conversion unit 4A that converts power supplied from the power supply 2 into necessary drive power in addition to wiring, screw terminals, various connectors, a backplane, a motherboard, and the like. As shown in FIG. 1, the power conversion unit 4A includes an AC-DC power supply device 4a connected to the power supply 2, and a DC-DC power supply circuit 4b connected between the AC-DC power supply device 4a and the measurement unit 3. Consists of The AC-DC power supply device 4a and the DC-DC power supply circuit 4b are connected via a power supply line 4 including, for example, wiring, screw terminals, connectors, and the like. Further, the DC-DC power supply circuit 4b and the measurement unit 3 are connected via a power supply line 4 including, for example, wiring, a hard metric connector, a backplane, a motherboard, and the like.

  Although not shown, the power supply line 4 connects the peripheral circuit of the measuring instrument including the potential difference detection unit 5, the voltage detection unit 6, the arithmetic processing unit 7 and the display unit 8 in FIG. The track is also included. The power supply line 4 connecting the AC-DC power supply device 4a and the DC-DC power supply circuit 4b has a length of, for example, 20 to 30 cm and a low electrical resistivity (for example, US wire gauge standard: AWG10). The following is used:

  The AC-DC power supply device 4a converts an AC power supply (AC100V) from the power supply 2 into a DC power supply (for example, ± 12V). The DC power converted by the AC-DC power supply device 4 a is supplied to the DC-DC power supply circuit 4 b through the power supply line 4.

  Note that a part of the direct-current power converted by the AC-DC power supply device 4a may be supplied to a load that requires a power supply voltage by the direct-current power. When the power source 2 is a DC power source, the DC power source can be supplied from the power source 2 to the DC-DC power source circuit 4b, and the configuration of the AC-DC power source device 4a can be omitted.

  The DC-DC power supply circuit 4b supplies the DC power supplied from the AC-DC power supply device 4a via the power supply line 4 to each load of the measuring instrument (in addition to the measurement unit 3, the potential difference detection unit 5, the voltage detection unit 6). , A DC power source (for example, ± 5 V, ± 3.3 V) corresponding to the power source type for each arithmetic processing unit 7 and peripheral circuit including the display unit 8. The power supply voltage by the direct-current power converted by the DC-DC power supply circuit 4b is supplied to the corresponding load.

  And in the measuring instrument which employs the overcurrent protection circuit 1 of this example, the AC-DC power supply device 4a and the DC-DC power supply circuit 4b are combined, and the power supply line 4 such as a wiring, a connector, a backplane, or a mother board is used. Thus, various power supply voltages are supplied to the measurement unit 3 and peripheral circuits.

  The potential difference detection unit 5 is provided at a place where monitoring on the power supply line 4 is necessary, detects a potential difference between two detection points, and can be configured by, for example, a differential amplifier. The potential difference detection unit 5 in FIG. 1 includes a potential difference between the output detection point P1 of the AC-DC power supply 4a and the input detection point P2 of the DC-DC power supply circuit 4b in the power supply line 4, DC− The potential difference between the detection point P3 on the output side of the DC power supply circuit 4b and the detection point P4 on the input side of the measurement unit 3 is detected. The potential difference signal between the detection points P1 and P2 detected by the potential difference detection unit 5 and the potential difference signal between the detection points P3 and P4 are input to the arithmetic processing unit 7 via a signal line.

  The voltage detection unit 6 detects a voltage at a location on the power supply line 4 that needs to be monitored, and can be configured by an A / D converter or a voltage comparator, for example. 1 includes a voltage at the detection point P1 on the output side of the AC-DC power supply device 4a, a voltage at the detection point P2 on the input side of the DC-DC power supply circuit 4b, and the DC-DC in the power supply line 4. The voltage at the detection point P3 on the output side of the power supply circuit 4b and the voltage at the detection point P4 on the input side of the measurement unit 3 are detected. The voltage signals at the detection points P1 to P4 detected by the voltage detection unit 6 are input to the arithmetic processing unit 7 through signal lines.

  Although not particularly illustrated, the potential difference detection unit 5 is not limited to the connection configuration in FIG. 1, and a power supply line between the AC-DC power supply device 4 a or the DC-DC power supply circuit 4 b and the peripheral circuit. 4 also detects a potential difference between detection points on the input side and the output side. Similarly, the voltage detection unit 6 also detects the voltage at the detection point on the input side and the output side on the power supply line 4 between the AC-DC power supply device 4a or the DC-DC power supply circuit 4b and the peripheral circuit.

  The arithmetic processing unit 7 is composed of, for example, a CPU, RAM, ROM, FPGA and the like. The arithmetic processing unit 7 multiplies the potential difference signal from the potential difference detection unit 5 by a predetermined conversion coefficient to convert it to a current value, compares the converted current value with the set current, and the converted current value is When the set current is exceeded, it is determined that there is an overcurrent (abnormal). When the arithmetic processing unit 7 determines that there is an overcurrent, the arithmetic processing unit 7 displays a message on the display unit 8 that there is an abnormality due to the overcurrent.

  The arithmetic processing unit 7 determines that there is an overcurrent (abnormality) when the current value exceeding the set current exceeds the set time or the set number of times, and displays a message to that effect on the display unit 8. Also good.

  The set current, the set time, and the set number of times are set in advance for each power supply type. The conversion coefficient is a coefficient for converting a voltage value into a current value, and is a value determined by variations in the line resistance of the power supply line 4 and the gains of the potential difference detection unit 5 and the voltage detection unit 6 in a section in which a potential difference or voltage is detected. It is.

  Further, the arithmetic processing unit 7 monitors the voltage signals of the detection points P1 to P4 input from the voltage detection unit 6, and displays the voltage values of the monitored voltage signals of the detection points P1 to P4 on the display unit 8. Display control on the screen. At that time, as a self-diagnosis, the arithmetic processing unit 7 compares the voltage value of each of the detected detection points P1 to P4 with a set voltage set in advance for each power supply type, and selects one of the detection points P1 to P4. When the voltage value exceeds the set voltage, it is determined that the voltage is abnormal, and a message to that effect is displayed on the display unit 8.

  In addition, the arithmetic processing unit 7 sequentially stores and holds a history of supplying power supply voltage from the power supply 2 to each load of the measuring instrument (presence of overcurrent for each power supply type, history of monitored voltage value). Thereby, the supply state of the power supply voltage to each load of the measuring instrument, the presence / absence of overcurrent and abnormality, and the like can be known from the history stored and held sequentially.

  The display unit 8 is composed of, for example, a liquid crystal display. The display unit 8 displays on the display screen the presence / absence of abnormality due to overcurrent or voltage abnormality and the monitored voltage values of the respective detection points P1 to P4 as the processing result of the arithmetic processing unit 7. Specifically, when the arithmetic processing unit 7 determines that there is an overcurrent (abnormality) or a voltage abnormality, a message to that effect is displayed on the display screen of the display unit 8 to prompt the user to warn. On the other hand, when the arithmetic processing unit 7 determines that there is no abnormality due to overcurrent or voltage abnormality, a message on the display screen of the display unit 8 indicates that the power supply voltage is normally supplied to each load of the measuring instrument. indicate. Thereby, when using a measuring instrument, the user can know the presence or absence of abnormality due to overcurrent or voltage abnormality from the display content of the display unit 8. In addition, the voltage values of the detection points P1 to P4 are displayed on a monitor screen. Thereby, the voltage of each detection point P1-P4 can be monitored.

  In FIG. 1, a configuration is used in which a message is displayed on the display screen of the display unit 8 to notify the user of the presence or absence of abnormality due to overcurrent or voltage, but the present invention is not limited to this configuration. For example, an LED lamp (for example, an LED lamp that lights (flashes red) in red) is provided as a part of the display unit 8, and the LED lamp is turned on when the arithmetic processing unit 7 determines that there is an abnormality due to overcurrent or a voltage abnormality ( (Flashing). In addition, for example, a notification unit such as a buzzer or a speaker may be provided separately, and when the arithmetic processing unit 7 determines that there is an abnormality due to overcurrent or a voltage abnormality, the user can be notified by sound. Furthermore, it is good also as a structure which uses a alerting | reporting part and the display part 8 together.

  Next, an overcurrent detection method and an overcurrent protection method for a measuring instrument using the overcurrent protection circuit (including an overcurrent detection circuit) 1 having the above configuration will be described.

  When AC power is supplied from the power supply 2, the AC-DC power supply device 4 a in the power supply line 4 converts the AC power into DC power and outputs the DC power to the DC-DC power circuit 4 b via the power supply line 4. . The DC-DC power supply circuit 4b converts the DC power input from the AC-DC power supply device 4a into DC power corresponding to the power supply type of each load. The DC power corresponding to the power type of each load converted by the DC-DC power supply circuit 4 b is supplied to the corresponding load via the power supply line 4. In the example of FIG. 1, the measurement unit 3 is shown as an example of a load, and DC power corresponding to the power type of the measurement unit 3 is supplied to the measurement unit 3 from the DC-DC power supply circuit 4 b via the power supply line 4. The

  As described above, in a state where a direct current corresponding to the power source type of each load is supplied, the potential difference detector 5 detects the detection point P1 on the output side of the AC-DC power supply device 4a in the power supply line 4 and the DC−. A potential difference between the detection point P2 on the input side of the DC power supply circuit 4b and a potential difference between the detection point P3 on the output side of the DC-DC power supply circuit 4b and the detection point P4 on the input side of the measurement unit 3 are detected. . Similarly, the potential difference detection unit 5 also detects a potential difference between input-side and output-side detection points on the power supply line 4 between the AC-DC power supply device 4a or the DC-DC power supply circuit 4b and the peripheral circuit.

  Further, the voltage detection unit 6 is configured to detect the voltage difference at the output side of the AC-DC power supply device 4a in the power supply line 4 and the input to the DC-DC power supply circuit 4b in parallel with the detection of the potential difference by the potential difference detection unit 5. The voltage at the detection point P2 on the side, the voltage at the detection point P3 on the output side of the DC-DC power supply circuit 4b, and the voltage at the detection point P4 on the input side of the measurement unit 3 are detected. Similarly, the voltage detection unit 6 also detects the voltage at the detection point on the input side and the output side on the power supply line 4 between the AC-DC power supply device 4a or the DC-DC power supply circuit 4b and the peripheral circuit.

  The arithmetic processing unit 7 multiplies each of the potential difference signals between the detection points input from the potential difference detection unit 5 by the conversion coefficient to convert it into a current value, compares the converted current value with the set current, When any of the current values exceeds the set current, it is determined that there is an overcurrent (abnormality) and a message is displayed on the display unit 8. The arithmetic processing unit 7 may determine that there is an overcurrent (abnormality) and display a message on the display unit 8 when the current value exceeding the set current exceeds the set time or the set number of times. When the current value exceeding the set current exceeds the set time or the set number of times, the arithmetic processing unit 7 switches the output of the AC-DC power supply device 4a to off, and overloads each load including the measuring unit 3 of the measuring instrument. Protect from.

  The arithmetic processing unit 7 monitors the voltage signal of each detection point input from the voltage detection unit 6 and displays the voltage value of the monitored voltage signal of each detection point on the display unit 8. At that time, the arithmetic processing unit 7 compares the monitored voltage value of each detection point with a set voltage set in advance for each power supply type, and when any voltage value of each detection point exceeds the set voltage. Then, it is determined that the voltage is abnormal, and a message to that effect is displayed on the display unit 8.

  As described above, in the overcurrent protection circuit 1 of this example, the potential difference between immediately after the power output of the power supply 2 and immediately before each load of the measuring instrument (only the measurement unit 3 is shown in FIG. 1) is supplied to each load. The potential difference detection unit 5 detects each power source type. Then, the arithmetic processing unit 7 compares the current based on the potential difference for each power source type detected by the potential difference detecting unit 5 with the set current for each power source type, and any of the currents based on the potential difference for each power source type corresponds. When the set current is exceeded, it is determined that there is an abnormality due to overcurrent. When it is determined that there is an abnormality due to overcurrent, a message is displayed on the display unit 8 to indicate that there is an abnormality due to overcurrent, and a warning is urged to the user. Furthermore, when there is an abnormality due to overcurrent, or when the state of abnormality due to overcurrent exceeds the set time or set number of times, the output of the AC-DC power supply device 4a is turned off and each load of the measuring instrument is overcurrent. Protect from.

  As a result, the load current can be easily reduced by using the line resistance remaining in the power supply line 4 such as the wiring, the connector, the backplane, and the mother board as the current detection resistance without using a resistor that causes a voltage drop as in the prior art. Can be measured. In particular, it is possible to construct a circuit that is advantageous for measuring a load current at a location where a large current of several tens of amperes flows or for measuring a low voltage in which voltage drop is a problem.

  Further, since the voltages at the plurality of detection points P1 to P4 in the power supply line 4 are detected by the voltage detector 6 and the voltages at the plurality of detection points P1 to P4 are constantly monitored, as a secondary effect, the power supply line 4 can detect the presence or absence of an abnormality in the line resistance.

  Furthermore, since the current flowing through each load of the measuring instrument is detected using the residual line resistance by the power supply line 4, the current measurement accuracy due to the variation in the line resistance is not so good, but can be realized easily and inexpensively. . At this time, if the variation in the line resistance is corrected at the time of calculation of the load current by the arithmetic processing unit 7, the measurement accuracy can be improved.

  The best mode of the overcurrent protection circuit and overcurrent protection method for a measuring instrument according to the present invention has been described above, but the present invention is not limited to the description and drawings according to this mode. That is, it is a matter of course that all other forms, examples, operation techniques, and the like made by those skilled in the art based on this form are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Overcurrent protection circuit 2 Power supply 3 Measurement part 4 Power supply line 4A Power supply conversion part 4a AC-DC power supply device 4b DC-DC power supply circuit 5 Potential difference detection part 6 Voltage detection part 7 Arithmetic processing part 8 Display part 9 Overcurrent detection circuit 51 Device 52 Line 53 Resistor 54 Reference Voltage Generation Means 55 Comparison Means P1, P2, P3, P4 Detection Point

Claims (8)

In an overcurrent protection circuit of an error rate measuring device for measuring an error rate when power corresponding to each load is supplied from a power source (2) via a power supply line (4) and a test signal is input to a device under test ,
A potential difference detector (5) for detecting a potential difference between two detection points for each power source type of power supplied to each load on the power supply line and outputting a potential difference signal;
The set number of times is set in advance for each power source type, and each potential difference signal input from the potential difference detection unit is multiplied by a predetermined conversion coefficient to be converted into a current value for each power source type. The converted current value for each power supply type is compared with a preset current for each power supply type set in advance, and any converted current value exceeds the set current corresponding to the power supply type of the current value , When the current value exceeding the set current exceeds the set number of times corresponding to the power source type of the current value, it is determined that there is an overcurrent, and the supply of power according to each load is shut off to An overcurrent protection circuit for an error rate measuring device , comprising: an arithmetic processing unit (7) for protecting a load . The overcurrent protection circuit for an error rate measuring apparatus according to claim 1, further comprising a display unit (8) for displaying the fact when it is determined that the overcurrent is present . The power supply line (4) includes an AC-DC power supply device (4a) connected to the power supply (2), and a DC-DC power supply circuit connected between the AC-DC power supply device and the loads. The overcurrent protection circuit for an error rate measuring apparatus according to claim 1 or 2, characterized by comprising (4b) . The overcurrent protection of the error rate measuring device according to any one of claims 1 to 3, further comprising a voltage detection unit (6) for detecting a voltage of a power source supplied to each load for each power source type. circuit. The overcurrent protection circuit for an error rate measuring device according to any one of claims 1 to 4, wherein a line resistance remaining in the power supply line (4) is used as a current detection resistor . In an overcurrent protection method of an error rate measuring device for measuring an error rate when power corresponding to each load is supplied from a power source (2) via a power supply line (4) and a test signal is input to a device under test ,
Detecting a potential difference between two detection points for each power source type of power supplied to each load on the power supply line and outputting a potential difference signal;
Setting a set number of times for each power source type;
Each potential difference signal is multiplied by a predetermined conversion coefficient to be converted into a current value for each power supply type, and the converted current value for each power supply type and a preset current for each power supply type set in advance. Any of the converted current values exceeds the set current corresponding to the power type of the current value, and the current value exceeding the set current exceeds the set number of times corresponding to the power type of the current value. An overcurrent protection method for an error rate measuring apparatus, comprising: a step of determining that there is an overcurrent and shutting off a supply of power according to each load to protect each load from the overcurrent . 7. The method of overcurrent protection for an error rate measuring apparatus according to claim 6, further comprising a step of displaying when it is determined that the overcurrent is present. The method for overcurrent protection of an error rate measuring device according to claim 6 or 7, further comprising the step of using the line resistance remaining in the power supply line (4) as a current detection resistance .

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