JP5509431B2 - Semiconductor circuit breaker and DC power supply system - Google Patents

Description

  The present invention relates to a semiconductor circuit breaker capable of interrupting an overcurrent that flows from a power supply device to a load device, and a DC power supply system including the semiconductor circuit breaker.

  In recent years, in data centers, communication stations, and the like, construction of a DC power supply system that supplies DC power to various load devices such as routers and servers has been promoted. The DC power supply system supplies DC power (DC current) from a power supply device to a load device via a power supply line. When supplying power from one power supply device to a plurality of load devices, the power supply device The direct current power is distributed by a current distribution device and supplied to a plurality of load devices.

  In such a DC power supply system, it is required to supply power to the load device with high reliability and high quality. For this reason, a protection device is provided between the power supply device and the load device in order to protect the system from an excessive short-circuit current that occurs when an accident such as a short circuit occurs on the load device side. In a system including the above-described current distribution device, a protection device is generally provided for each distribution destination in the power distribution device.

  As a protection device, a fuse has been generally used. However, in the case of a fuse, it is necessary to replace it every time it is blown by overcurrent, or when a high-voltage DC power supply system is used, a fuse with a rating corresponding to that is required. There is a difficulty in terms of labor and cost, such as the need to use it. Therefore, various semiconductor circuit breakers have been proposed as a protection device that replaces the fuse, in which a semiconductor switching element is inserted on the power supply line, and the power supply line can be turned on and off by the semiconductor switching element.

  The semiconductor circuit breaker always turns on the semiconductor switching element during normal operation and supplies power from the power supply device to the load device. However, when the current flowing through the semiconductor switching element exceeds a certain threshold value, that is, an overcurrent state occurs. If this occurs, this is detected and the semiconductor switching element is turned off to cut off the overcurrent.

  By the way, the occurrence of an overcurrent is not limited to the case where a short circuit accident occurs, for example, it occurs due to an inrush current or noise that flows instantaneously, or occurs when a capacitance component (capacitor) on the load device side is charged. Even if the system is normal, it may occur. The capacitor on the load device side is, for example, a capacitor constituting an input filter (LC filter) provided in the input stage of the load device, or a power storage for compensating the power supply to the load device when the power supply is momentarily interrupted. Any capacitor (capacitance component) existing in the circuit on the load device side from the semiconductor circuit breaker, such as a capacitor as a means, is included.

  Such an overcurrent due to an inrush current or a capacitor charging current, unlike an accident current due to a short circuit or the like, does not occur due to an abnormality in the system. Therefore, when such an overcurrent is detected, it is not always necessary. There is no need for continuous interruption.

  Therefore, in the past, when an overcurrent occurred, it was determined whether it was an accident current due to a short circuit or a temporary one such as a capacitor charging current. There are known techniques for turning off the power (see, for example, Patent Documents 1 and 2).

  The techniques described in Patent Documents 1 and 2 determine whether or not the current flowing through the semiconductor switching element is equal to or greater than a threshold value. If the current exceeds the threshold value, the semiconductor switching element is turned on / off (hereinafter referred to as “retry operation”). Is used to limit the short-circuit current. Each time the retry operation is performed, that is, every time the power is turned off and then turned on again, it is determined whether or not the current is below the threshold value by looking at the current passing through the semiconductor switching element when the power is turned on. Then, the retry operation is repeated until the value falls below the threshold value, and if the value falls below the threshold value, the retry operation is stopped and the semiconductor switching element is always returned to the on state.

  On the other hand, if the threshold value is not less than the threshold value after repeating the retry operation for a predetermined time, it is determined that the accident current is caused by a short circuit or the like, and the semiconductor switching element is completely turned off.

JP 2007-236061 A Japanese Patent No. 3400302

  However, the overcurrent caused by the capacitor charging current increases the time required for charging as the capacitance of the capacitor on the load side increases, and the overcurrent state continues for a long time. Then, after the retry operation is started due to the occurrence of an overcurrent, even if a predetermined time elapses, the charging is not completed and the overcurrent state still remains, which is erroneously determined as an accident current due to a short circuit or the like, and the semiconductor switching element Is completely turned off and the power supply to the load device is stopped.

In order to reliably charge the battery while preventing the erroneous determination as described above even when the capacity of the capacitor is large, for example, a method of setting a long predetermined time permitting the retry operation is conceivable.
However, in such a case, even if a short circuit accident has actually occurred and the accident current is flowing, the retry operation will be repeated until the set time has elapsed, and it is determined that there is a short circuit accident or a semiconductor The timing for completely turning off the switching element is delayed.

  On the other hand, a method for setting a threshold value for determining whether or not an overcurrent is set to a high value without changing the predetermined time during which the retry operation is permitted is also conceivable. However, when doing so, overcurrent other than accidental current due to a short circuit or the like flows, that is, a current that is smaller than the short circuit current but larger than the rating flows, and the semiconductor switching element should be in a retry operation. Regardless of the case, the retry operation is not performed because the threshold value is not equal to or greater than the threshold value, and the device is always turned on. For this reason, it is not realistic to set a high threshold value for determining whether or not there is an overcurrent because the overcurrent determination function itself deteriorates.

  The present invention has been made in view of the above problems, and it is possible to accurately determine whether or not an overcurrent has occurred due to a short circuit or the like on the load device side when an overcurrent occurs while sufficiently maintaining the overcurrent determination function. It is an object to provide a semiconductor circuit breaker capable of quickly determining and quickly interrupting an overcurrent in the case of an accident current, and to provide a DC power supply system including the semiconductor circuit breaker. To do.

  The invention according to claim 1, which has been made to solve the above-described problems, is a continuity between the power supply device and the load device in a DC power supply system that supplies DC power from the power supply device to the load device via the power supply line. A semiconductor circuit breaker provided on a power supply line for cutting off, a semiconductor switch means inserted on the power supply line, and made of a semiconductor switching element for conducting / cutting off the power supply line, and a power supply device Current detection means for detecting the current flowing through the semiconductor switch means to the load device, and overcurrent determination for determining whether the current detected by the current detection means is an overcurrent that is equal to or greater than a preset current threshold And a retry operation that repeats turning on and off of the semiconductor switch means at a predetermined timing when the overcurrent is determined by the overcurrent determination means. When the overcurrent is determined by the live control means, the voltage detection means for detecting the voltage output to the load device via the power supply line, and the overcurrent determination means, a preset value is set after the determination. Voltage determination means for determining whether or not the voltage detected by the voltage detection means satisfies a preset continuous cutoff unnecessary condition until the determination required period elapses, and until the determination required period elapses by this voltage determination means And a blocking means for continuously turning off the semiconductor switch means when it is not determined that the voltage detected by the voltage detection means satisfies the continuous cutoff unnecessary condition.

  In the semiconductor circuit breaker according to claim 1 configured as described above, when power is supplied from the power supply device to the load device, the semiconductor switch device is turned on to supply power via the semiconductor switch device. Current flows on the wire. When the current becomes equal to or greater than the current threshold (overcurrent), a retry operation is performed.

  While based on such an operation, the present invention is further configured to detect the voltage output to the load device via the power supply line. And when it is judged that it is an overcurrent, it is judged whether a voltage satisfy | fills the continuous interruption | blocking unnecessary condition after the judgment required period passes after the judgment is made.

  There are various causes for the occurrence of overcurrent. For example, in the case of an accident current due to a short-circuit failure on the load device side, the voltage on the load device side greatly decreases and the state continues because of the short-circuit failure. On the other hand, for example, when an overcurrent occurs due to the charging current to the capacitor (capacitance component) of the load device, the overcurrent is temporary and the charging current gradually decreases as the capacitor is charged. I will do it. Therefore, as for the voltage on the load device side, immediately after the overcurrent occurs, the charge amount of the capacitor is still small and the charge current is large. Accordingly, the voltage increases and eventually becomes a value equivalent to the DC voltage supplied from the power supply device.

  In other words, there is a difference in the voltage change on the load device side after the overcurrent occurs between the overcurrent (accident current) caused by a short circuit accident etc. and the overcurrent (charge current) caused by charging the capacitor on the load device side. is there.

  Therefore, in the present invention, based on the voltage after the occurrence of the overcurrent, it is determined whether or not the overcurrent is an accident current due to a short circuit or the like. Specifically, when it is determined that the current is an overcurrent, it is determined whether or not the voltage satisfies the continuous cutoff unnecessary condition until the determination required period elapses after the determination is made. If it is not determined that the continuous interruption unnecessary condition is satisfied, it is presumed that an accident current due to a short circuit or the like is flowing, so that the overcurrent is interrupted by continuously turning off the semiconductor switch means. To do.

  Therefore, according to the semiconductor circuit breaker of the first aspect, when the overcurrent is generated while sufficiently maintaining the determination function for the overcurrent at the level at which the retry operation should be performed, it is caused by a short circuit on the load device side or the like. Whether or not the current is an accident current can be determined accurately and quickly. Therefore, in the case of an accident current, the accident current can be quickly interrupted by turning off the semiconductor switch means. In addition, for example, when an excessive charging current temporarily flows to the capacitor on the load device side, it can be avoided that it is erroneously determined as an accident current, and the capacitor can be reliably charged.

  Next, the invention according to claim 2 is the semiconductor circuit breaker according to claim 1, wherein the continuous interruption unnecessary condition is determined as an overcurrent by the overcurrent determination means until a determination required period elapses. In addition, the voltage detected by the voltage detecting means is equal to or higher than a preset voltage threshold.

  When a short circuit failure occurs on the load device side, the voltage on the load device side (voltage detected by the voltage detection means) is close to 0 V if the impedance of the power supply line from the power supply device to the load device is ignored. descend. As long as the short-circuit failure continues, the state (a state close to 0 V) continues.

  On the other hand, when an overcurrent occurs due to a charging current for the capacitor (capacitance component) of the load device, the voltage on the load device side decreases to a value close to 0 V just like the short-circuit failure immediately after the occurrence of the overcurrent. The voltage gradually increases as the charging of the battery proceeds, and eventually exceeds the voltage threshold.

  Therefore, in the present invention (Claim 2), when the voltage on the load device side does not become equal to or higher than the voltage threshold before the determination required period elapses after an overcurrent occurs, an accident current due to a short circuit or the like flows. The semiconductor switch means is continuously turned off under the assumption that the overcurrent is interrupted.

  Therefore, according to the semiconductor circuit breaker according to claim 2, it is possible to easily determine whether or not the overcurrent is an accident current such as a short circuit by a simple determination method of whether or not the voltage threshold is exceeded. Can do.

  Next, the invention according to claim 3 is the semiconductor circuit breaker according to claim 1, wherein the continuous interruption unnecessary condition is determined as an overcurrent by the overcurrent determination means until the determination required period elapses. In addition, the amount of change in voltage detected by the voltage detection means is equal to or greater than a preset voltage change amount threshold.

  More specifically, how much the voltage on the load device side (the voltage detected by the voltage detection means) decreases when a short-circuit fault occurs on the load device side, more specifically, the impedance of the power supply line from the power supply device to the load device It depends on (especially the inductance component). That is, when the short-circuit fault occurs, the voltage on the load device side is the output voltage of the power supply device, the impedance of the current path from the power supply device to the voltage detection site (hereinafter referred to as “power supply side impedance”) and the voltage detection site to the load device. This value is almost the same as the value divided by the ratio to the impedance of the current path (hereinafter referred to as “load-side impedance”).

  Therefore, if the load side impedance is sufficiently smaller than the power supply side impedance, the voltage on the load device side at the time of the short circuit failure will be close to 0V, but the short circuit becomes larger as the load side impedance becomes relatively larger than the power supply side impedance. The voltage on the load device side at the time of failure becomes a value larger than 0V.

  Therefore, the method of judging based on the voltage threshold as in the invention described in claim 2 considers the impedance ratio when the voltage on the load device side becomes larger than 0 V due to the impedance ratio as described above. Therefore, it is necessary to set the voltage threshold value to an appropriate value (in accordance with the voltage value on the actual load device side at the time of a short-circuit failure), which may lead to an increase in design man-hours.

  On the other hand, in the semiconductor circuit breaker according to the third aspect, it is determined whether the current is an accident current based on the amount of change in the voltage, not the voltage value itself. In other words, how much the voltage drops immediately after the overcurrent due to the charging current to the capacitor varies depending on the impedance ratio as described above, but after the overcurrent occurs, the charge is charged regardless of the magnitude of the voltage immediately after the overcurrent occurs. As the voltage progresses, the voltage gradually increases. Therefore, if the voltage change amount threshold value is set appropriately and the voltage change amount is equal to or greater than the voltage change amount threshold value, it can be determined as a charging current to the capacitor.

  Therefore, according to the semiconductor circuit breaker according to claim 3, an overcurrent is generated regardless of the impedance ratio (that is, regardless of how much the voltage on the load device decreases when the overcurrent is generated). In this case, it can be easily determined whether or not the current is an accident current due to a short circuit or the like.

  Next, the invention according to claim 4 is the semiconductor circuit breaker according to any one of claims 1 to 3, wherein the determination required period is a period until a predetermined determination time elapses. This is a period in which the retry operation by the retry control means is performed a predetermined number of times.

According to the semiconductor circuit breaker according to claim 4 configured as described above, the degree of freedom for setting the determination required period is widened, and a highly versatile semiconductor circuit breaker can be provided.
Next, the invention according to claim 5 is the semiconductor circuit breaker according to any one of claims 1 to 4, wherein the retry control means is determined to be overcurrent by the overcurrent determination means. If the voltage detection means determines that the voltage detected by the voltage detection means satisfies the continuous interruption unnecessary condition until the determination required period elapses after the retry operation is started, the preset retry stop is set. The retry operation is stopped after the condition is satisfied.

  That is, even if it is determined that the current is an overcurrent, if the voltage satisfies the continuous interruption unnecessary condition until the determination required period elapses, it is estimated that the current is not an accident current such as a short circuit, and the load device Depending on the condition of the side, it is expected that the overcurrent will eventually settle. In particular, in the case of the above-described capacitor charging current, as the charging proceeds, the current falls within the original steady state level. If the overcurrent is settled, there is no need to perform the retry operation, and the semiconductor switch means may be continuously turned on.

  Therefore, in the semiconductor circuit breaker according to claim 5, when the voltage satisfies the continuous interruption unnecessary condition until the determination required period elapses, the retry operation is continued until the retry stop condition is satisfied, but the retry stop is performed. When the condition is satisfied, the retry operation is stopped to return to a steady state in which the semiconductor switch means is continuously turned on.

  Therefore, according to the semiconductor circuit breaker according to claim 5, when the overcurrent is not an accident current due to a short circuit or the like, the retry operation is excessively performed while the semiconductor circuit breaker and the load device are protected from the overcurrent by the retry operation. It is possible to return to the steady state more quickly without continuing.

  Next, the invention according to claim 6 is the semiconductor circuit breaker according to claim 5, wherein the retry stop condition is that a predetermined retry time elapses from the start of the retry operation or the retry operation is performed. The retry operation is performed more than the preset number of retries from the start of the operation.

  According to the semiconductor circuit breaker of the sixth aspect configured as described above, the timing for stopping the retry operation can be set easily and appropriately. For overcurrent other than accidental current such as short circuit, depending on the cause, it is possible to roughly estimate the time until the overcurrent is settled. For example, in the case of the charging current to the capacitor described above, if the capacity on the load device side is known, the time required for the charging current to settle can be accurately estimated. Therefore, if the retry time or the number of retries is set according to the estimated time, it is possible to set a more appropriate timing for stopping the retry operation.

Next, the invention according to claim 7 is the semiconductor circuit breaker according to claim 5, wherein the retry stop condition is that the current detected by the current detecting means falls below the current threshold.
In the first place, the retry control means starts the retry operation when it is determined as an overcurrent. Therefore, it is appropriate to determine whether or not to perform the retry operation based on whether or not it is in an overcurrent state. It can be said that. Therefore, if the retry operation is stopped when the current falls below the current threshold (that is, when the overcurrent state is not reached), the retry operation can be stopped at a more appropriate timing.

  Next, an invention according to claim 8 is a DC power supply system that supplies DC power from a power supply device to a plurality of load devices, and distributes the DC power from the power supply device to a plurality of systems, for each system. Each is configured to supply DC power to one or a plurality of load devices via current supply lines. And the semiconductor circuit breaker of any one of Claims 1-7 is provided in at least 1 of each electric current supply line.

  In the DC power supply system configured as described above, since the power supply system is distributed to a plurality of systems, for example, if a short circuit accident occurs in one system and an excessive accident current flows, the influence is affected. Of course, this system extends to other normal systems.

  Therefore, if a semiconductor circuit breaker according to the present invention (Claims 1 to 7) is provided for such a DC power supply system, even if a short circuit accident occurs and an excessive accident current flows in a certain system, it can be quickly detected. It can block | block, and it can suppress significantly the influence on another normal system | strain by this.

It is a lineblock diagram showing a schematic structure of a direct-current power supply system of a 1st embodiment. It is a figure showing the operation example of the semiconductor circuit breaker of 1st Embodiment, (a) represents the operation example when the charging current to the capacitor | condenser on the load apparatus side flows, (b) represents the short circuit accident on the load apparatus side. An operation example in the case where an accident current flows due to is shown. It is a flowchart showing the overcurrent protection control process of 1st Embodiment. It is a flowchart showing the overcurrent protection control process of 2nd Embodiment. It is a flowchart showing the overcurrent protection control process of 3rd Embodiment.

Preferred embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
(1) Configuration of DC Power Supply System FIG. 1 shows a schematic configuration of a DC power supply system according to an embodiment to which the present invention is applied. As shown in FIG. 1, the DC power supply system 1 of the present embodiment supplies DC power from a power supply device 3 to a plurality of load devices 21, 22, 23... Via power supply lines 7, 8. It is configured.

  The DC power from the power supply device 3 is distributed to a plurality of systems by the current distribution device 5 and supplied to the corresponding load device for each system. FIG. 1 shows a configuration in which one load device is connected to one system as an example.

  The power supply device 3 supplies DC power for operation to each of the load devices 21, 22, 23..., And in this embodiment, the rated output voltage is 400V, for example. As a specific configuration of the power supply device 3, for example, a configuration including a rectifier that converts commercial AC power into DC power is conceivable. However, as long as DC power of a predetermined voltage can be supplied to the load device side. The specific configuration is not particularly limited.

  Each of the load devices 21, 22, 23... Is operated by DC power from the power supply device 3, but in the present embodiment, each of the load devices 21, 22, 23. The input stage is provided with an input filter (LC filter) composed of a capacitor and a coil for stabilization of input power and countermeasures against noise. Further, any one or a plurality of load devices 21, 22, 23,... Has a power storage means (capacitor) for compensating the operating voltage when the DC power supply from the power supply device 3 is momentarily interrupted. Is provided.

  That is, each load device 21, 22, 23... Is a load having a capacitor (capacitance component) when viewed from the power supply device 3, and therefore each of these load devices 21, 22, 23. When power is supplied to the capacitor, an excessive charging current to the capacitor may flow as described later.

  The current distribution device 5 is provided to distribute and supply the DC power from the power supply device 3 to each of the load devices 21, 22, 23. In the DC power supply system 1 of the present embodiment, an overcurrent larger than the rated current may flow in each system distributed by the current distribution device 5. Specifically, there is an overcurrent that continuously occurs due to an accident such as a short circuit on the load device side, or an overcurrent that temporarily occurs when a charging current flows to the capacitor on the load device side as described above. Conceivable.

  Therefore, the current distribution device 5 is provided with a semiconductor circuit breaker for detecting an overcurrent flowing to the load device side for each distributed system and interrupting it as necessary. That is, one semiconductor circuit breaker 11 is provided in the system to one load device 21 among the plurality of load devices 21, 22, 23... A semiconductor circuit breaker 12 is provided, and one semiconductor circuit breaker 13 is also provided in a system to another load device 23.

  In the present embodiment, since the plurality of semiconductor circuit breakers 11, 12, 13,... Provided in the current distribution device 5 have basically the same structure, the structure of one semiconductor circuit breaker 11 is representatively shown. Will be explained.

  The semiconductor circuit breaker 11 includes a semiconductor switch unit 31 provided in one of the two power supply lines 7 and 8 and a current flowing through the power supply line 7 provided with the semiconductor switch unit 31. A current sensor 32 for detection and a voltage sensor 33 for detecting a voltage between the power supply lines 7 and 8 on the downstream side (load device side) of the semiconductor switch unit 31 (that is, an output voltage to the load device 21). And a control circuit 34 that controls the operation (on / off) of the semiconductor switch unit 31 based on the detection results of the current sensor 32 and the voltage sensor 33.

  Of the two power supply lines 7, 8, one power supply line 7 provided with the semiconductor switch unit 31 is connected to the positive side of the DC power supply (DC voltage) in the power supply device 3, and the other power The supply line 8 is connected to the negative electrode side of the DC power supply in the power supply device 3. However, there is no particular limitation as to which of the power supply lines 7 and 8 the semiconductor switch unit 31 and the current sensor 32 are provided, and the semiconductor switch unit 31 supplies DC power to the load device 21 side. As long as the current sensor 32 can be cut off, and as long as the current flowing to the load device 21 can be detected, the specific power supply line can be determined as appropriate.

  The semiconductor switch unit 31 includes a semiconductor switching element (not shown; for example, MOSFET) inserted on the power supply line 7, and a drive signal from the control circuit 34 (details from a drive unit 45 described later). The semiconductor switching element is turned on / off according to the drive signal). That is, when the semiconductor switching element is, for example, a MOSFET, the source is connected to the power supply device 3 side, the drain is connected to the load device 21 side, and the drive signal from the control circuit 34 is input to the gate.

  In the following description, the term “on” and “off” for the semiconductor switch unit 31 means “on (turn on)” and “off (turn off)” of the semiconductor switching elements constituting the semiconductor switch unit 31 in detail. It shall be.

  Therefore, while the semiconductor switch unit 31 is turned on, the power supply line 7 provided with the semiconductor switch unit 31 is turned on, and power can be supplied from the power supply device 3 to the load device 21. On the contrary, while the semiconductor switch unit 31 is turned off, the power supply line 7 provided with the semiconductor switch unit 31 is cut off, and the power supply from the power supply device 3 to the load device 21 is cut off.

  The control circuit 34 measures the current value detected by the current sensor 32 and outputs data (current Id) indicating the current value, and measures the voltage value detected by the voltage sensor 33. A voltage measurement unit 42 that outputs data (voltage Vd) indicating the voltage value, and a measurement value storage unit that stores data (current Id, voltage Vd) output from the current measurement unit 41 and the voltage measurement unit 42 43 and various determinations to be described later based on the current Id and voltage Vd stored in the measured value storage unit 43, and a control signal for turning on or off the semiconductor switch unit 31 is output according to the determination result. A control unit 44, and a drive unit 45 for turning on and off the semiconductor switch unit 31 by outputting a drive signal to the semiconductor switch unit 31 in accordance with a control signal from the control unit 44; It includes a setting information storage unit 46 in which various setting information used for various determinations are stored performed in control unit 44.

  The setting information storage unit 46 includes, as setting information, a “current threshold value” used as a determination criterion for determining whether or not the current flowing through the semiconductor switch unit 31 is in an overcurrent state, and the semiconductor switch unit 31. When the flowing current becomes an overcurrent state, the “voltage threshold” used as a criterion for determining whether or not the overcurrent is an accident current due to a short circuit or the like on the load device 21 side, and an accident due to a short circuit or the like The “determination time T1” used as a determination criterion for making a final determination as to whether or not the current is current, and after the retry operation of the semiconductor switch unit 31 is started due to an overcurrent state, the overcurrent is short-circuited, etc. When it is determined that the accident current is not, the “retry time T2” used as a reference for determining the timing for stopping the retry operation is stored. The setting information is input and stored in advance from an external setting device (not shown) via the input interface 35.

  In the present embodiment, as shown in FIG. 2, as an example, the current flowing through the power supply lines 7 and 8 in a steady state is about 2.5 [A], and the current threshold is set to 4 [A]. The voltage threshold is set to 1 [V]. The determination time T1 is set to be shorter than the retry time T2. This FIG. 2 will be described later.

  Note that the measurement of the current Id by the current measurement unit 41 and the measurement of the voltage Vd by the voltage measurement unit 42 are both performed according to a measurement instruction from the control unit 44. In addition, during the retry operation, a measurement instruction is issued so as to measure the current Id and voltage Vd (peak value) when the semiconductor switch unit 31 is turned on. Each time measurement is performed in accordance with the measurement instruction, the measurement result storage unit 43 stores the current Id and the voltage Vd as the measurement results.

(2) Description of Operation of Semiconductor Circuit Breaker Next, the operation of the semiconductor circuit breaker 11 configured as described above will be described with reference to FIG. FIG. 2A shows an operation example when an overcurrent occurs due to the charging current of the capacitor flowing to the load device 21, and FIG. 2B shows an accident due to an accident such as a short circuit on the load device 21 side. An operation example in the case where an overcurrent occurs due to a current flowing is shown.

  As shown in FIG. 2A, when a capacitor charging current flows to the load device 21 while a current of 2.5 [A] flows in a steady state, the current threshold (4 [A]) is exceeded ( Time t = 0). That is, it becomes an overcurrent state. In this way, when the current threshold value is exceeded, the control unit 44 outputs a control signal for performing the retry operation of the semiconductor switch unit 31 to the drive unit 45 to perform the retry operation, thereby performing the semiconductor switch unit 31. The current flowing to the load device 21 side is limited.

  In the retry operation, as shown in FIG. 2A, the semiconductor switch unit 31 is repeatedly turned on and off at predetermined timings. Various timings for stopping the retry operation are conceivable. In the present embodiment, as will be described later, the retry operation is determined by the elapsed time from the start of the retry operation. In a third embodiment to be described later, it is determined depending on whether or not the current threshold value is below.

  In the example of FIG. 2A, since the generated overcurrent is a capacitor charging current, a large overcurrent exceeding the current threshold flows as illustrated. On the other hand, the voltage on the load device 21 side (hereinafter also simply referred to as “load side”) should be close to the rated 400 [V] originally, but the beginning of excessive charging current flow is close to 0 [V]. Value, which is lower than the voltage threshold.

  As described above, the state where the current on the load side flows while the current on the load side becomes a value close to 0 [V] is shown in FIG. 2B in addition to the case of the capacitor charging current. This also occurs when an accident current due to an accident such as a short circuit on the load device 21 side flows (time t = 0). For this reason, even when the overcurrent above the current threshold begins to flow, even if the voltage on the load side becomes lower than the voltage threshold, it is difficult to determine whether it is a capacitor charging current or an accident current at that time. .

  However, in the case of an accident current, as shown in FIG. 2B, the voltage on the load side changes little near 0 [V], whereas in the case of a capacitor charging current, the voltage in FIG. As shown in a), the voltage gradually increases as the charging of the capacitor proceeds, and when a certain amount of time has passed (time t1), the voltage becomes equal to or higher than the voltage threshold value.

  Therefore, the control unit 44 determines whether the current is a capacitor charging current or an accident current by utilizing the property that the voltage on the load side eventually becomes equal to or higher than the voltage threshold in the case of the capacitor charging current as described above. . Specifically, the process waits for the determination time T1 to elapse after the occurrence of an overcurrent exceeding the current threshold (time t = 0). When the determination time T1 elapses (time t2), the voltage on the load side at that time is set. measure. And when the measured voltage is more than a voltage threshold value, it determines with a capacitor charging current, and when it is less than a voltage threshold value, it determines with it being an accident current.

  Since FIG. 2A shows the capacitor charging current, the voltage on the load side is equal to or higher than the voltage threshold before the determination time T1 elapses. Therefore, in this case, the capacitor is continuously charged while continuing the retry operation. When the retry time T2 elapses from the start of the retry operation (time t = 0) (time t3), the retry operation is stopped, the semiconductor switch unit 31 is continuously turned on, and the steady state is restored.

  On the other hand, since FIG. 2B shows an accident current, the load-side voltage is smaller than the voltage threshold even when the determination time T1 has elapsed. Therefore, in this case, the retry operation is stopped after the determination time T1 has elapsed, and the semiconductor switch unit 31 is continuously turned off. That is, the power supply from the power supply device 3 to the load device 21 is completely cut off.

  In the determination time T1, when an overcurrent that causes the load-side voltage to approach 0 [V] is generated by the capacitor charging current, the load-side voltage rises above the voltage threshold as the capacitor is charged. It is set in consideration of the time required for. That is, when the capacitor charging current is used, a time during which the load-side voltage is likely to be equal to or higher than the voltage threshold before the determination time T1 elapses is appropriately set. However, when an accident current due to a short circuit or the like occurs, it is necessary to determine this as quickly as possible to turn off the semiconductor switch unit 31. From the viewpoint of quick protection from an accident current, the determination time T1 is as long as possible. Shorter is better.

  Therefore, the determination time T1 is set in consideration of the balance with the voltage threshold so that both accurate determination of the capacitor charging current and accurate and quick determination of the accident current are possible. Is done.

(3) Description of Overcurrent Protection Control Processing Next, the overcurrent protection control processing executed by the control unit 44 for operating the semiconductor circuit breaker 11 as described above will be described with reference to the flowchart of FIG. The flowchart of FIG. 3 shows a process after the steady power supply to the load device 21 is started when the semiconductor switch unit 31 is turned on.

  When starting the steady power supply, the controller 44 first measures the current Id in S110. Specifically, a measurement instruction is issued to the current measurement unit 41, and the measurement result is acquired from the measurement value storage unit 43. In step S120, the timer t is reset.

  In S130, it is determined whether or not the measured current Id is an overcurrent equal to or greater than a current threshold. At this time, if it is below the current threshold value, the process returns to S110 again. If it is equal to or greater than the current threshold value, a retry operation is started in S140, and a timer t is started in S150. Then, in subsequent S160, it is determined whether or not the timer t (specifically, the measured time) is equal to or greater than the determination time T1, and the process waits until it reaches the determination time T1.

  Then, when the timer t reaches the determination time T1 or more, the voltage Vd is measured in S170. Specifically, a measurement instruction is issued to the voltage measurement unit 42, and the measurement result is acquired from the measurement value storage unit 43. In S180, it is determined whether or not the measured voltage Vd is equal to or higher than a voltage threshold value.

  If the voltage Vd is below the voltage threshold value, the process proceeds to S230, and an accident determination is made that the accident current is due to a short circuit or the like. After the accident determination, the retry operation is stopped in S240, and the semiconductor switch unit 31 is continuously turned off in S250, and the overcurrent protection control process is terminated.

  On the other hand, if the voltage Vd is greater than or equal to the voltage threshold value in S180, it is determined that the cause of the overcurrent is not an accident current due to a short circuit or the like, and that the retry operation may be continued as it is. Wait until t reaches the retry time T2 or more. That is, the retry operation is continued until the retry time T2 is reached.

  When the timer t reaches the retry time T2 or longer, the retry operation is stopped in S200, and in S210, the semiconductor switch unit 31 is continuously turned on to return to the steady state. In S220, it is determined whether or not the overcurrent protection control process including the power supply to the load device 21 should be stopped. If it should be continued, the process returns to S110, and if it should be stopped, the process proceeds to S250. Thus, the semiconductor switch unit 31 is continuously turned off.

(4) Effects of the First Embodiment In the semiconductor circuit breaker 11 of the present embodiment described above, the semiconductor switch unit 31 is used to determine whether it is an accident current such as a short circuit when an overcurrent occurs. A current sensor 32 for detecting a flowing current and a voltage sensor 33 for detecting a voltage on the load side are provided, and a current threshold for overcurrent determination and a voltage threshold for accident determination are set.

  When the detected current Id becomes an overcurrent that is equal to or greater than the current threshold, the process waits for the determination time T1 to elapse since the overcurrent is reached. When the determination time T1 elapses, the voltage on the load side at that time is observed, and if it is below the voltage threshold, it is determined that the current is an accident due to a short circuit or the like.

  Therefore, when an overcurrent occurs while sufficiently maintaining a determination function (basic function) for an overcurrent (overcurrent greater than the current threshold) at which retry operation should be performed, this is a short circuit on the load device 21 side. Whether or not the fault current is caused by the above or the like can be accurately and quickly determined by a simple method of comparison with the voltage threshold. For this reason, in the case of an accident current, the semiconductor switch unit 31 can be quickly turned off to quickly interrupt the accident current.

  In addition, when excessive charging current temporarily flows to the capacitor on the load device 21 side, the current becomes equal to or higher than the current threshold, but the load side voltage becomes equal to or higher than the voltage threshold before the determination time T1 elapses thereafter. If it becomes, it will not be determined as an accident current. Therefore, it can be avoided that the capacitor charging current is erroneously determined as an accident current, and the capacitor can be reliably charged.

  If the load-side voltage becomes equal to or higher than the voltage threshold before the determination time T1 elapses, the retry operation is continued until the retry time T2 elapses, and then the retry operation is stopped, and the semiconductor switch unit 31 is continuously turned on.

  Therefore, when the overcurrent is not an accident current due to a short circuit or the like, it is possible to return to the steady state more quickly without continuing the retry operation excessively while protecting the system from the overcurrent by the retry operation. .

  In the DC power supply system 1 of the present embodiment, the power supply system is distributed to a plurality of systems, and semiconductor breakers 11, 12, 13... Are provided for each system. For this reason, for example, even if an accident such as a short circuit occurs in one system and an excessive current flows, it can be quickly shut off, greatly reducing the impact of the accident on other normal systems be able to.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In the present embodiment, the semiconductor switch unit 31 corresponds to the semiconductor switch means of the present invention, the current sensor 32 corresponds to the current detection means of the present invention, the voltage sensor 33 corresponds to the voltage detection means of the present invention, and the control circuit. Reference numeral 34 corresponds to an overcurrent determination unit, a voltage determination unit, a retry control unit, and a cutoff unit of the present invention.

[Second Embodiment]
In the first embodiment, when the current Id is in an overcurrent state that is equal to or greater than the current threshold, is the voltage Vd when the determination time T1 has elapsed from when the current Id is in the overcurrent state equal to or greater than the voltage threshold? Based on whether or not, it is determined whether or not the current is an accident current (see S160 to S180 in FIG. 3).

  On the other hand, in the present embodiment, when an overcurrent state occurs, an accident current is generated based on the amount of change in the voltage Vd from when the overcurrent state is reached until the determination time T1 elapses. It is determined whether or not. More specifically, the amount of change from the voltage Vd (= Vd1) at the time of the overcurrent state to the voltage Vd (= Vd2) when the determination time T1 has elapsed does not exceed the voltage change amount threshold value. In addition, it is determined as an accident current.

  Therefore, the semiconductor circuit breaker of the present embodiment is partially different from the semiconductor breaker 11 of the first embodiment shown in FIG. Specifically, instead of the voltage threshold in the first embodiment, a voltage change amount threshold is set in the present embodiment. Along with this, part of the overcurrent protection control process executed by the control unit 44 is also different. About the structure of those other than these, it is the same as the semiconductor circuit breaker 11 of 1st Embodiment.

  Next, the overcurrent protection control process executed by the control unit 44 in the semiconductor circuit breaker of this embodiment will be described with reference to FIG. Of the overcurrent protection control processing of FIG. 4, the processing of S310 to S330, the processing of S350 to S370, and the processing of S400 to S460 are respectively the overcurrent protection control processing of the first embodiment shown in FIG. Are the same as the processing of S110 to S130, the processing of S140 to S160, and the processing of S190 to S250, and detailed description of these processes is omitted here.

  If the overcurrent state is entered after the start of the overcurrent protection control process of FIG. 4 (S330: YES), the voltage Vd at that time is measured in S340, and the measurement result is stored as the voltage Vd1. After that, a retry operation is started to start the timer t (S350, S360), and waits until the determination time T1 elapses (S370).

  When the timer t becomes equal to or longer than the determination time T1, the voltage Vd at that time is measured in S380, and the measurement result is stored as the voltage Vd2. In subsequent S390, it is determined whether or not the difference between the stored voltage Vd2 and the voltage Vd1 measured and stored in S340 is equal to or greater than a voltage change amount threshold value. That is, it is determined whether or not the change amount of the voltage Vd from the time when the overcurrent state is determined until the determination time T1 elapses is equal to or greater than the voltage change amount threshold value.

  If the change amount of the voltage Vd is not equal to or greater than the voltage change amount threshold value (S390: NO), the process proceeds to S440, where an accident determination is made that the accident current is due to a short circuit or the like, and then the retry operation is stopped (S450). The semiconductor switch unit 31 is continuously turned off (S460).

  On the other hand, if the change amount of the voltage Vd is equal to or greater than the voltage threshold (S390: YES), it is determined that the cause of the overcurrent is not an accident current due to a short circuit or the like, and that the retry operation may be continued as it is. It progresses to the process after S400.

  As described above, in the overcurrent protection control process of the present embodiment, the accident determination based on the voltage threshold as in the overcurrent protection control process (FIG. 3) of the first embodiment, that is, the voltage Vd when the determination time T1 has elapsed. Unlike the accident determination based on the value itself, the accident determination based on the voltage change amount is performed.

  The voltage Vd at the time of the short-circuit failure of the load device 21 includes the impedance of the current path from the power supply device 3 to the voltage sensor 33 (power supply side impedance) and the impedance of the current path from the voltage sensor 33 to the load device 21 (load side impedance). However, the voltage Vd at the time of the short-circuit fault becomes larger than 0V as the ratio of the load side impedance increases. As described above, when the voltage Vd at the time of the short circuit failure is larger than 0 V, it is difficult to appropriately set the voltage threshold in the overcurrent protection control process of the first embodiment.

  On the other hand, in the overcurrent protection control process of the present embodiment, whether or not the current is an accident current is determined based on the voltage change amount, not the voltage value itself, so regardless of the impedance ratio (that is, Regardless of how much the voltage on the load device decreases when an overcurrent occurs), it is possible to easily determine whether or not an overcurrent has occurred due to a short circuit or the like.

[Third Embodiment]
In the first embodiment, when the current Id is in an overcurrent state that is equal to or greater than the current threshold value, the system waits until the determination time T1 elapses. In this configuration, it is determined whether or not the current is current (see S160 to S180 in FIG. 3). In addition, if the accident current is not determined even though the overcurrent state has occurred, the retry operation is continued until the retry time T2 elapses after the overcurrent state is reached, and the retry operation is performed when the retry time T2 elapses. Is stopped and the system shifts to a steady state (continuation of ON) (see S190 to S210 in FIG. 3).

  In contrast, in the present embodiment, when an overcurrent state occurs, whether or not the voltage Vd is equal to or higher than the voltage threshold is determined one by one until the determination time T1 elapses. In addition, if the accident current is not determined although the overcurrent state has occurred, the retry operation is stopped when the current Id falls below the current threshold.

  Therefore, the semiconductor circuit breaker of the present embodiment is partially different from the semiconductor breaker 11 of the first embodiment shown in FIG. Specifically, the retry time T2 in the first embodiment is not necessary. Along with this, part of the overcurrent protection control process executed by the control unit 44 is also different. About the structure of those other than these, it is the same as the semiconductor circuit breaker 11 of 1st Embodiment.

  Next, the overcurrent protection control process executed by the control unit 44 in the semiconductor circuit breaker of this embodiment will be described with reference to FIG. Of the overcurrent protection control processing of FIG. 5, the processing of S510 to S550 is exactly the same as the processing of S110 to S150 in the overcurrent protection control processing of the first embodiment shown in FIG. Detailed description thereof is omitted.

  When the overcurrent state is entered (S530: YES), when the retry operation is started and the timer t is started (S540, S550), the voltage Vd is measured in S560. In S570, it is determined whether or not the measured voltage Vd is equal to or higher than a voltage threshold value.

  At this time, if the voltage Vd is below the voltage threshold value, the process proceeds to S630, where it is determined whether the timer t is equal to or greater than the determination time T1. If the timer t has not yet reached the determination time T1, the process returns to S560. However, if the timer t reaches the determination time T1 or more, the process proceeds to S640, and an accident determination is made that the accident current is due to a short circuit or the like. After the accident determination, the retry operation is stopped in S650, and in the subsequent S660, the semiconductor switch unit 31 is continuously turned off, and the overcurrent protection control process is terminated.

  On the other hand, if it is determined in S570 that the voltage Vd is greater than or equal to the voltage threshold, the current Id is measured in S580, and it is determined in subsequent S590 whether or not the current Id is greater than or equal to the current threshold. If the current Id is equal to or greater than the current threshold, the process returns to S580. That is, the processes of S580 to S590 are repeated until the current Id falls below the current threshold.

  Then, when the current Id is gradually decreased to fall below the current threshold value, the retry operation is stopped in S600, and in S610, the semiconductor switch unit 31 is continuously turned on to be in a steady state. return. Then, in S620, it is determined whether or not the overcurrent protection control process including the power supply to the load device 21 should be stopped. If it should be continued, the process returns to S510, and if it should be stopped, the process proceeds to S660. Thus, the semiconductor switch unit 31 is continuously turned off.

[Modification]
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the first and third embodiments, when an overcurrent state occurs, it is determined whether it is an accident current due to a short circuit or the like until the determination time T1 elapses after the overcurrent state is reached. However, instead of this, the voltage Vd becomes equal to or higher than the voltage threshold before the retry operation is performed a predetermined number of times after the overcurrent state is reached. It may be determined depending on whether or not. That is, instead of the accident determination based on the elapsed time after the overcurrent state, the accident determination is based on the number of executions of the retry operation.

  Similarly, in the second embodiment, the determination may be made based on whether or not the change amount of the voltage Vd is equal to or greater than the voltage change amount threshold after the retry operation is performed a predetermined number of times after the overcurrent state is reached. Good.

  Further, as shown in S190 of FIG. 3, in the first embodiment, when the voltage Vd becomes equal to or higher than the voltage threshold, the retry operation is continued until the retry time T2 elapses. The retry operation may be continued up to a predetermined number of retries. The same applies to the processing of S400 of the second embodiment, and instead of the processing of S400 (continuing the retry operation until the retry time T2 elapses), the retry operation is continued up to a predetermined number of retries. Also good.

  In the overcurrent protection control process of the third embodiment shown in FIG. 5, when the voltage Vd is equal to or higher than the voltage threshold in S570, the retry operation is stopped when the current Id falls below the current threshold. However, depending on the situation on the load device side (S580 to S600), for example, an overload state may occur, and the state above the current threshold may continue for a long time. Therefore, for example, when the state where the current Id is equal to or greater than the current threshold value continues for a predetermined time, an appropriate process such as turning off the semiconductor switch unit 31 may be performed.

  Moreover, in the said embodiment, although the semiconductor circuit breaker was provided in all the some systems distributed by the electric current distribution apparatus 5, this is an example, Comprising: It is not necessary to provide a semiconductor circuit breaker in all the systems.

  In the above embodiment, the DC power supply system 1 configured to distribute DC power from the power supply device 3 to a plurality of systems by the current distribution device 5 has been described. It goes without saying that the present invention can also be applied to a DC power supply system.

  DESCRIPTION OF SYMBOLS 1 ... DC power supply system, 3 ... Power supply device, 5 ... Current distribution device, 7, 8 ... Electric power supply line, 11, 12, 13 ... Semiconductor breaker, 21, 22, 23 ... Load device, 31 ... Semiconductor switch part, 32 ... Current sensor, 33 ... Voltage sensor, 34 ... Control circuit, 35 ... Input interface, 41 ... Current measurement unit, 42 ... Voltage measurement unit, 43 ... Measurement value storage unit, 44 ... Control unit, 45 ... Drive unit, 46 ... Setting information storage

Claims (8)

In a DC power supply system for supplying DC power from a power supply device to a load device via a power supply line, a semiconductor circuit breaker provided in the power supply line to conduct / cut off between the power supply device and the load device. There,
Semiconductor switch means comprising a semiconductor switching element, inserted on the power supply line, for conducting / interrupting the power supply line;
Current detection means for detecting a current flowing from the power supply device to the load device via the semiconductor switch means;
Overcurrent determination means for determining whether or not the current detected by the current detection means is an overcurrent that is equal to or greater than a preset current threshold;
Retry control means for performing a retry operation that repeats ON / OFF of the semiconductor switch means at a predetermined timing when the overcurrent is determined by the overcurrent determination means;
Voltage detection means for detecting a voltage output to the load device via the power supply line;
When the overcurrent determination unit determines that the overcurrent is present, the voltage detected by the voltage detection unit is not required to be continuously interrupted until a predetermined determination required period elapses after the determination. Voltage judging means for judging whether or not the condition is satisfied;
When the voltage determination means does not determine that the voltage detected by the voltage detection means satisfies the continuous cutoff unnecessary condition before the determination required period elapses, the semiconductor switch means is continuously turned off. Blocking means;
A semiconductor circuit breaker comprising: The semiconductor circuit breaker according to claim 1,
The continuous interruption unnecessary condition is that the voltage detected by the voltage detection unit is equal to or higher than a preset voltage threshold after the determination current period elapses after the overcurrent determination unit determines the overcurrent. A semiconductor circuit breaker characterized by that. The semiconductor circuit breaker according to claim 1,
The continuous interruption unnecessary condition is a voltage change in which a change amount of the voltage detected by the voltage detection unit is determined in advance from the time when the overcurrent determination unit determines that the overcurrent has elapsed until the determination required period elapses. A semiconductor circuit breaker characterized by having a quantity threshold value or more. The semiconductor circuit breaker according to any one of claims 1 to 3,
The determination required period is a period until a predetermined determination time elapses or a period in which the retry operation by the retry control unit is performed a predetermined number of determinations. The semiconductor circuit breaker according to any one of claims 1 to 4,
The retry control means is detected by the voltage detection means by the voltage determination means until the determination required period elapses after the retry operation is started when the overcurrent determination means determines the overcurrent. When it is determined that the voltage to be applied satisfies the continuous interruption unnecessary condition, the retry operation is stopped after a preset retry stop condition is satisfied. The semiconductor circuit breaker according to claim 5,
The retry stop condition is that a predetermined retry time elapses from the start of the retry operation, or the retry operation is performed for a predetermined number of times from the start of the retry operation. Semiconductor breaker to do. The semiconductor circuit breaker according to claim 5,
The retry stop condition is that the current detected by the current detection means falls below the current threshold. A DC power supply system for supplying DC power from a power supply device to a plurality of load devices,
DC power from the power supply device is distributed to a plurality of systems, and each system is configured to supply DC power to one or a plurality of load devices via current supply lines, respectively.
A DC power supply system, wherein the semiconductor circuit breaker according to any one of claims 1 to 7 is provided in at least one of the current supply lines.

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