JP2014158365A - Dc power feeding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power feeding system capable of reducing abnormal current which flows when electric leakage occurs due to foreign matter and electrical conduction materials of an operator or the like.SOLUTION: A DC power feeding system for feeding DC voltage to load includes: a detection circuit 130 which detects electric leakage between each bus bar to feed DC voltage and ground; a discharge circuit 20 in which bus bars 120A, 120B are connected to the ground, respectively; and a control circuits 10 in which, when the detection circuit 130 detects the electric leakage, the discharge circuit 20 is controlled, and the bus bar having electric leakage is connected to the ground to make a potential of this bus bar equal to that of the ground.

Description

  The present invention relates to a DC power supply system that supplies a DC voltage to various devices, and more particularly to a DC power supply system that copes with leakage occurrence.

  There is a high voltage direct current (HVDC) as a direct current power supply. For example, in the case of a data center that accommodates a large number of servers, positive and negative DC high voltages are supplied by high-voltage DC power supply instead of supplying AC power to each server. Such direct current power supply eliminates the need for conversion from alternating current to direct current at each server, so that efficient use of electricity is performed (see, for example, Patent Document 1).

  An example of a power supply system for performing this high-voltage DC power supply is shown in FIG. The power supply system includes a power supply device 110, buses 120 </ b> A and 120 </ b> B, a detection circuit 130, a control circuit 140, and a high-resistance grounding circuit 150, and supplies a DC high voltage to the electronic device 200. The power supply device 110 is a floating power supply, generates DC high voltages from an AC power supply or the like, and outputs these DC high voltages to the buses 120A and 120B. The bus bars 120 </ b> A and 120 </ b> B send a DC high voltage to the electronic device 200.

  Capacitors C211 and C212 are provided on the input side of the electronic apparatus 200 as Y capacitors (Y capacitors) for noise removal and the like. Capacitor C211 is connected between the bus 120A side for sending a positive DC high voltage and the ground, and capacitor C212 is connected between the bus 120B side for sending a negative DC high voltage and the ground. Has been. In the electronic device 200, a high DC voltage from which noise or the like has been removed is applied to the electronic device main body 210. Note that when the power supply system is installed in a data center, for example, the electronic device 200 is a device such as a server. And although illustration is abbreviate | omitted, the several electronic apparatus 200 is connected in parallel with respect to bus-line 120A, 120B, and DC high voltage is supplied. That is, a high DC voltage of a magnitude corresponding to the difference between the positive DC high voltage on the bus 120A and the negative DC high voltage on the bus 120B is applied to the electronic device main body 210.

  The detection circuit 130 detects a leakage caused by a foreign object, a conductor such as an operator, etc. coming into contact with the bus bars 120A and 120B. The detection circuit 130 generates a detection signal that is a detection result of leakage, and sends this detection signal to the control circuit 140.

  The control circuit 140 controls the high resistance ground circuit 150 based on the detection signal from the detection circuit 130. That is, when the detection signal is not output from the detection circuit 130, the control circuit 140 sends an ON control signal to the high-resistance ground circuit 150. When the detection signal is output, the control circuit 140 increases the OFF control signal. Send to the resistance ground circuit 150.

  The high resistance ground circuit 150 includes resistors R1 and R2 and a switch 151. In high-resistance ground circuit 150, a series circuit of resistors R1 and R2, which are high resistances, is connected between bus 120A and bus 120B. A switch 151 is connected between the connection point 152 of the resistors R1 and R2, that is, the middle point, and the ground. The switch 151 is turned on upon receiving an ON control signal from the control circuit 140, and connects the connection point 152 of the resistors R1 and R2 to the ground. Thereby, the midpoint ground is performed, and the midpoint becomes the same potential as the ground. Further, the switch 151 is turned off when it receives an off control signal from the control circuit 140 and opens the connection between the connection point 152 and the ground.

  In such a DC power supply system, for example, as shown in FIG. 9, a leakage accident caused by a foreign object or an operator occurs in the bus 120 </ b> A that supplies a positive DC high voltage, and the fault point 121 passes through the foreign object or the operator. An abnormal current flows to the ground. Note that the abnormal current due to leakage is a current that flows to a foreign object or an operator when a conductive object or an operator contacts the bus 120A or the bus 120B. The detection circuit 130 sends a detection signal to the control circuit 140 when detecting that a foreign object, an operator, or the like has contacted the bus 120 </ b> A. The control circuit 140 normally sends an ON control signal to the high-resistance ground circuit 150, but when receiving a detection signal from the detection circuit 130, sends an OFF control signal to the high-resistance ground circuit 150.

Since the switch 151 of the high-resistance ground circuit 150 normally receives an ON control signal, the switch 151 is in an ON state and connects the connection point 152, which is the middle point, to the ground. In this state, when the high resistance ground circuit 150 receives an off control signal from the control circuit 140, the switch 151 of the high resistance ground circuit 150 is turned off, and the connection between the connection point 152 and the ground is released. As a result, the path of the abnormal current flowing from the accident point 121 to the ground through a foreign object, an operator, or the like is blocked. For example, when the operator touches the bus 120A and receives an electric shock, a path through which an abnormal current flows due to the electric shock, that is,
Bus 120A → Accident point 121 → Worker → Ground → Switch 151 →
Middle point → Resistance R2 → Bus 120B
Since the path formed as described above is blocked by the off switch 151, the influence on the operator is eliminated.

JP 2010-193614 A

  In the DC power feeding system described above, the detection point 130 and the control circuit 140 and the high resistance grounding method using the high resistance grounding circuit 150 allow the middle point that is the connection point 152 of the resistors R1 and R2 to be set when a leakage occurs. This is a method of cutting off the path of abnormal current that flows to conductive foreign objects, workers, etc. by disconnecting from the ground. However, this method has the following problems. In this system, when a leakage occurs, the middle point that is the connection point 152 of the resistors R1 and R2 is opened. However, if there is a midpoint at another location, for example, the load side, this midpoint is always grounded with high resistance. As a result, when an abnormal current occurs, even if the switch 151 of the high-resistance ground circuit 150 of the DC power supply system is turned off, the abnormal current continues to flow through the middle point on the load side. Thereby, for example, when an operator is electrocuted, an abnormal current flows.

  In addition, when electric leakage occurs, the electric charges of the capacitor C211 and the capacitor C212 provided in the electronic device 200 as a load are discharged through a foreign object, a worker, or the like, resulting in a longer time for the abnormal current to flow. .

  An object of the present invention is to solve the above-described problems and to provide a DC power supply system that can shorten the time of an abnormal current that flows when a leakage due to a conductive material such as a foreign object or an operator occurs.

  In order to solve the above-described problems, the invention of claim 1 is a DC power supply system that supplies a DC voltage to a load, and a detection circuit that detects a leakage between each bus supplying the DC voltage and the ground. The discharge circuit for connecting each of the buses to the ground and the detection circuit detect the leakage, the discharge circuit is controlled, the leaking bus is connected to the ground, and the potential of the bus is made the same as the ground. A DC power supply system.

  In the invention of claim 1, the DC power supply system includes a detection circuit, a discharge circuit, and a control circuit. When the detection circuit detects a leakage between each bus supplying the DC voltage and the ground, the control circuit controls the discharge circuit to connect the leaking bus to the ground.

  According to a second aspect of the present invention, in the DC power supply system according to the first aspect, the control circuit controls the discharge circuit after a predetermined time after discharging the electric charge on the busbar side that is leaking electric current. And the connection to the ground is released.

  According to the first aspect of the present invention, when a leak is detected, the leaking bus is connected to the ground, and the potential of the bus is made the same as that of the ground. Thereby, the leakage current that flows when the leakage occurs can be reduced. For example, when a capacitor is provided on the load side, the charge of the capacitor can also be discharged.

  According to the second aspect of the present invention, the connection between the bus bar and the ground is released after a predetermined time after discharging the electric charge on the leaking bus bar side, so that the bus side charge can be reliably discharged.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows an example of the DC power supply system by Embodiment 1 of this invention. It is a block diagram which shows an example of a detection circuit. It is a block diagram which shows an example of a discharge circuit. It is a block diagram which shows an example of a control circuit. It is a flowchart which shows an example of an opening / closing process. It is explanatory drawing explaining generation | occurrence | production of a leak. It is explanatory drawing explaining operation | movement of a discharge circuit. It is a block diagram which shows an example of the conventional electric power feeding system. It is explanatory drawing explaining operation | movement of a high resistance grounding circuit.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
A DC power supply system according to this embodiment is shown in FIG. In this embodiment, components that are the same as or the same as those in FIG. 8 described above are denoted by the same reference numerals, and description thereof is omitted. 1 includes a power supply device 110, buses 120A and 120B, and a detection circuit 130, as in FIG. Further, the DC power supply system includes a control circuit 10 and a discharge circuit 20. The DC power supply system supplies positive and negative DC high voltages to the ground to the electronic device 200 that is a load. For example, when the power supply system is installed in a data center, the electronic device 200 is a server device. When the server receives a DC high voltage of, for example, several hundred volts from the buses 120A and 120B, the server performs step-down of this voltage to make the power supply have a voltage of several tens of volts.

  The detection circuit 130 detects a leakage as described above. An example of this embodiment is shown in FIG. The detection circuit 130 in FIG. 2 includes resistors R131 to R135. In detection circuit 130, a series circuit of resistors R131 and R132 is connected between bus 120A and bus 120B, and a series circuit of resistors R133 and R134 is connected between bus 120A and bus 120B. ing. As a result, a bridge circuit is formed by the resistors R131 to R134. A connection point 131 between the resistor R131 and the resistor R132 is connected to the ground via the resistor R135, and a connection point 132 between the resistor R133 and the resistor R134 is directly connected to the ground, so that the bridge circuit is balanced. The resistor R135 has a higher resistance than the resistors R131 to R134, and performs high-resistance grounding at the connection point 131. The voltage change at the connection point 131 is sent to the control circuit 10 as a detection signal.

  The detection circuit 130 detects electric leakage as follows. Usually, the bridge circuit by the resistors R131 to R134 is balanced and outputs a zero voltage from the connection point 131. In this state, for example, if a leakage accident due to a foreign object or a conductor such as an operator occurs in the bus 120A that supplies a positive DC high voltage, the resistance due to the conductor enters between the fault point 121 and the ground. become. As a result, a resistor made of a conductive material is connected in parallel to the resistor R133 of the bridge circuit, and the bridge circuit using the resistors R131 to R134 becomes unbalanced. When the bridge circuit becomes unbalanced, the zero voltage changes and a voltage is generated at the connection point 131 of the detection circuit 130. The detection circuit 130 outputs the changed voltage to the control circuit 10 as a detection signal.

  As shown in FIG. 3, the discharge circuit 20 includes switches 21 and 22. The switch 21 is an open / close switch. One end of the switch 21 is connected to the bus 120A, and the other end is connected to the ground. If the control signal a1 is not output from the control circuit 10, the switch 21 is open. In addition, when the switch 21 receives the control signal a1 instructing closing from the control circuit 10, the switch 21 closes and connects the bus 120A to the ground. Thereby, the switch 21 sets the potential of the bus 120A to the ground. At the same time, the switch 21 also discharges the electric charge of the capacitor C211 of the electronic device 200 that is a load.

  Similarly, the switch 22 is an open / close switch, and one end of the switch 22 is connected to the bus 120B and the other end is connected to the ground. If the control signal a2 is not output from the control circuit 10, the switch 22 is open. Further, when the switch 22 receives the control signal a2 instructing the closing from the control circuit 10, the switch 22 is closed and connects the bus 120B to the ground. As a result, the switch 22 sets the potential of the bus 120B to the ground. At the same time, the switch 22 discharges the electric charge of the capacitor C212 of the electronic device 200 that is a load.

  The control circuit 10 generates control signals a1 and a2 based on the detection signals from the detection circuit 130, and sends these control signals a1 and a2 to the discharge circuit 20. An example of the control circuit 10 is shown in FIG. The control circuit 10 includes interfaces 11 and 13 and a processing unit 12. The interface 11 is used to connect the detection circuit 130 to the processing unit 12 and performs voltage level conversion and the like. Similarly, the interface 13 is for connecting the discharge circuit 20 to the processing unit 12, and performs voltage level conversion and the like.

  The processing unit 12 of the control circuit 10 is a circuit that controls the discharge circuit 20 based on the output of the detection circuit 130. When the detection circuit 130 outputs zero voltage, the processing unit 12 does not output a control signal to the detection circuit 130.

  On the other hand, when the processing unit 12 receives a detection signal from the detection circuit 130 via the interface 11, the processing unit 12 performs an open / close control process. When the opening / closing process shown in FIG. 5 is started, the processing unit 12 examines the bus where the leakage has occurred, for example, from the polarity of the detection signal (step S1). Then, the processing unit 12 selects a switch connected to the bus checked in step S1 from the switches 21 and 22 of the discharge circuit 20 (step S2). The processing unit 12 sends a control signal instructing closing to the switch of the discharge circuit 20 selected in step S2 via the interface 13 (step S3). After step S3, the processing unit 12 checks the elapsed time (step S4). In step S4, the processing unit 12 uses a timer function provided therein.

  The processing unit 12 determines whether or not the elapsed time checked in step S4 has exceeded a predetermined time (step S5). The predetermined time in step S5 is a time for discharging all the capacitors C211 and C212 of the electronic device 200, and is set in the processing unit 12 in advance. When determining that the predetermined time has not elapsed in step S5, the processing unit 12 returns the process to step S4. If it is determined in step S5 that the predetermined time has elapsed, the processing unit 12 checks the detection signal from the detection circuit 130 (step S6) and determines whether the detection signal is output (step S7). In steps S6 and S7, it is determined whether or not a conductive material such as a foreign object or an operator is still in contact with the busbar. If the process part 12 determines with the detection signal being output by step S7, it will return a process to step S6. If it is determined in step S7 that there is no detection signal, the processing unit 12 stops outputting the control signal that instructs the switch of the discharge circuit 20 to close (step S8). When step S8 ends, the open / close control process ends.

  The control circuit 10 that performs such processing is composed of, for example, a one-chip controller.

  Next, the operation of the DC power supply system according to this embodiment will be described. The power supply device 110 supplies a DC voltage to the electronic device 200 through the bus bars 120A and 120B. In this state, since the detection circuit 130 has not detected a leakage, it outputs a zero voltage. Thereby, since the control circuit 10 does not output the control signals a1 and a2 to the switches 21 and 22 of the discharge circuit 20, the switches 21 and 22 are in an open state.

  By the way, for example, as shown in FIG. 6, when a conductor such as a foreign object or an operator comes into contact with the bus 120A, the detection circuit 130 detects a leakage due to the conductor, and generates a detection signal indicating the leakage detection. Send to control circuit 10. Thereby, the control circuit 10 performs an opening / closing control process, and sends a control signal a1 instructing closing to the switch 21 of the discharge circuit 20 connected to the bus 120A. When the switch 21 of the discharge circuit 20 receives the control signal a1, it is closed as shown in FIG. As a result, the bus 120 </ b> A has the same potential as the ground, and prevents current from flowing from the contact point 121 toward the ground via a foreign object or an operator. At the same time, since the switch 21 is connected in parallel to the capacitor C211 of the electronic device 200, the charge of the capacitor C211 of the electronic device 200 is also discharged.

  Thus, according to this embodiment, when a conductive object such as a foreign object or an operator comes into contact with the bus bars 120A and 120B, the potential of the bus bar on the contact side is made the same as the ground. Can be reduced. At the same time, the electric charge of the Y capacitor provided on the load side is discharged by the switch 21 and the switch 22 of the discharge circuit 20, so that it is possible to prevent the electric charge of the Y capacitor from flowing into a foreign substance or a conductor such as an operator due to electric leakage. it can.

  Furthermore, according to this embodiment, when a leakage occurs due to a foreign object or a conductor such as an operator, the bus 120A or the bus 120B is set to the same potential as the ground, so the electronic device 200 on the load side has a midpoint. However, it is possible to prevent an abnormal current from flowing through the middle point on the load side as in the prior art.

(Embodiment 2)
In this embodiment, the control of the control circuit 10 is performed as follows. In this embodiment, components that are the same as or the same as those in FIG. 1 described above are denoted by the same reference numerals, and description thereof is omitted. In this embodiment, the control circuit 10 checks whether the opening / closing control processing for the bus has already been performed before starting the opening / closing control processing. When the opening / closing control process is being performed, the current opening / closing control process is performed after the opening / closing control process that has already been completed is completed.

  According to this embodiment, it is possible to prevent the switch 21 and the switch 22 of the discharge circuit 20 from being closed simultaneously, thereby preventing a short circuit between the bus 120A and the bus 120B.

DESCRIPTION OF SYMBOLS 10 Control circuit 20 Discharge circuit 21, 22 Switch 110 Power supply device 120A, 120B Bus-line 130 Detection circuit

Claims (2)

In a DC power supply system that supplies a DC voltage to a load,
A detection circuit for detecting a leakage between each bus bar supplying the DC voltage and the ground;
A discharge circuit for connecting each of the buses to the ground;
When the detection circuit detects a leakage, the control circuit controls the discharge circuit, connects the leaking bus to the ground, and makes the potential of the bus the same as the ground;
A direct current power supply system comprising: The control circuit controls the discharge circuit after a predetermined time to finish discharging the electric charge on the busbar side that is leaking, and opens the connection between the busbar and the ground.
The DC power supply system according to claim 1, wherein