JP2009033790A - Charging monitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect leakage even at very low level by preventing impact on the precision of leakage detection employing a zero-phase current transformer while having circuitry for detecting the existence of welding individually at each relay contact provided on each AC line by detecting a voltage between a ground line. <P>SOLUTION: The charging monitor is provided with a switch 11 interposed between an external power supply AC and a battery 53 and having relay contacts 111 and 112 for opening/closing two AC lines L1 and L2 individually is further provided with a voltage monitor 25 for detecting generation of a voltage between each AC line closer to the battery 53 side than the switch 11 and a sub-ground line S-GND branched from a ground line GND under a state where the switch 11 is designated to open state, and a leakage detection means 26 having a zero-phase current transformer 12 for detecting a level difference of currents flowing through the two AC lines L1, L2 and the sub-ground line S-GND on the side closer to the external power supply AC than the switch 11 and judging that leakage has occurred if there is a difference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is provided between an external AC power source and a ground battery from the external AC power source and a storage battery charged via the two AC lines, and each relay contact for individually opening and closing the two AC lines. It is related with the charge monitoring apparatus provided with the switch which has.

  Conventionally, an electric vehicle driven by using electric power from the battery and an auxiliary power supply system that can take out the electric power stored in the battery when necessary are known. It is mainly carried out from an external AC power source for home use or industrial use. In this case, electric leakage may occur during charging due to poor connection between the charging line and the device or an insulation defect that may occur around the battery of the device. Such leakage is desired to be detected at an early stage for reasons such as electric shock, device failure, and loss of charging efficiency. In addition, in the structure in which the device is insulated from the ground, there may be a feeling of uncomfortable feeling when the leakage charge during charging flows to the ground through the human body.

  Therefore, as shown in Patent Document 1, charging is performed in a state where a charging device including a relay is interposed between the external AC power source and the battery. This relay is an electromagnetic relay having a relay contact for each of two AC lines from an external AC power source. Then, as shown in Patent Document 1, when leakage is confirmed by the leakage detection circuit, both relay contacts of the electromagnetic relay are simultaneously switched to the open state to open the external AC power source from the battery side.

  By the way, since charging of the battery of this type of device is performed with a comparatively large current of several tens of amperes, the relay contact repeatedly melts slightly due to a transient inrush current that occurs during repeated on / off. Depending on the case, there is a risk of welding to the fixed end. For this reason, conventionally, a charge monitoring device having a circuit for detecting welding of an electromagnetic relay is known. This welding detection circuit detects the presence or absence of a voltage between two AC lines in a state in which an instruction signal for opening an electromagnetic relay is provided while being connected to an external AC power source. If there is welding.

Furthermore, as a technique for detecting welding between a relay contact and a fixed point, as shown in Patent Document 2, in an electric vehicle, welding detection provided in the middle of two current supply lines connecting a battery and an inverter. The device is known. This welding detection device is adapted to detect the presence or absence of welding for each of the main relays R1 and R2 interposed in each of the two current supply lines, and detects the presence or absence of welding for each one. Therefore, the abnormality of the relay is detected as soon as possible before both relay contacts are welded.
JP-A-11-205909 JP 2006-310219 A

  However, the welding detection device described in Patent Document 2 is a so-called individual relay in which the main relays R1 and R2 can be independently driven on and off. Therefore, the detection operation is performed in order while sequentially supplying a drive signal to each relay. It is different from one electromagnetic relay in which each relay contact is turned on and off in synchronization. By the way, as a circuit configuration for individually detecting the presence or absence of welding of each relay contact of the electromagnetic relay, when the electromagnetic relay is instructed to be in an open state, a pair of each detecting the presence or absence of a voltage between each AC line and the ground line. One having a circuit is conceivable.

  On the other hand, unlike Patent Document 1, a zero-phase current transformer that has been conventionally inserted with two AC lines from an external AC power source as the primary side is provided to detect minute electric leakage, and flows through both AC lines. In general, a leakage monitoring apparatus that can detect a minute leakage current by detecting a difference in current level is generally employed. Therefore, when a pair of circuit configurations are used as the welding detection circuit, the current flowing between the AC lines becomes unbalanced due to the current flowing through the welding detection circuit between one AC line and the ground line, and the leakage detection circuit malfunctions. There is a possibility of doing.

  The present invention has been made in view of the above, and has a circuit configuration that individually detects the presence or absence of welding of each relay contact provided in each AC line by detecting the voltage between the relay line and the ground line. It is an object of the present invention to provide a leakage monitoring device that prevents an influence on the accuracy of leakage detection using a phase current transformer and prevents erroneous detection even for leakage at a minute level.

  The invention according to claim 1 is interposed between an external AC power source, a ground line from the external AC power source, and a storage battery charged via the two AC lines, and individually opens and closes the two AC lines. In the charge monitoring device including a switch having each relay contact, the sub-ground branched from the AC line and the ground line on the storage battery side with respect to the switch in a state where the switch is instructed to be opened Contact state detection means for detecting the generation of a voltage between the line and the difference between the levels of currents flowing through the two AC lines and the sub-ground line on the external AC power supply side of the switch. It has a zero-phase current transformer and includes a leakage detection means for determining a leakage when there is a difference.

  According to this configuration, the switch interposed between the external AC power source, the ground line from the external AC power source, and the storage battery charged via the two AC lines has two AC lines individually. Each relay contact opens and closes. Accordingly, in addition to the case where both relay contacts are welded, only one relay contact may be welded in the switch. With the switch instructed to be in the open state, the contact state detection means detects the occurrence of voltage between each AC line on the storage battery side relative to the switch and the sub-ground line branched from the ground line. Is done. If voltage generation is detected on at least one side, the corresponding relay contact is welded. If no voltage generation is detected on either side, in principle there is no welding of each relay contact. become. Further, the difference in the level of the current flowing through the two AC lines and the sub ground line on the external AC power supply side from the switch is detected as a voltage via the zero-phase current transformer. If a differential voltage is detected, it is determined that there is a leakage, and if not, it is determined that there is no leakage. Here, during the charging operation, a part of the AC current flows from each AC line through a loop of the sub ground line through the contact state detection means, and this sub ground line should be the primary side of the zero-phase current transformer. As a result, the number of flux linkages between the AC line and the sub-ground line is canceled, and as a result, the leakage detection means does not perform false detection even if the welding state detection means is present, and a small level of leakage is prevented. Can also be detected.

  According to a second aspect of the present invention, in the charge monitoring apparatus according to the first aspect, the contact state detecting means has a direct current component cut-off circuit for cutting off a direct current component at an input stage thereof. According to this configuration, even if the welding state is detected while the battery is connected, all direct current flowing from the battery side is cut off, so that the influence on the battery side is eliminated when detecting the welding state. The In this configuration, although there is current circulation from the AC line to the sub-ground line, since the sub-ground line is the primary side of the zero-phase current transformer, the influence is eliminated as described above. .

  According to the first aspect of the present invention, the leakage detection means does not perform erroneous detection even by the presence of the welding state detection means, and it is possible to detect even a minute level of leakage.

  According to the second aspect of the present invention, even if the welding state is detected in a state where the battery is connected, all direct current flowing from the battery side is cut (excluding the influence on the battery side), and welding is performed. The presence or absence of can be detected. Moreover, since the sub ground line is the primary side of the zero-phase current transformer, the influence of the current circulation from the AC line to the sub ground line can be eliminated as described above.

  FIG. 1 is a block diagram showing an embodiment in which the charge monitoring device according to the present invention is applied to a charging device including a storage battery (battery). In FIG. 1, a charge monitoring device 1 includes a plug P1 connected to the external AC power supply AC side and a plug (socket) P2 connected to a battery of the charging device (load unit), and a circuit for monitoring the charge therebetween. It has a block. Between the plugs P1 and P2, AC signal lines L1 and L2 (Hot, Cold), a ground line (GND), and a control signal line to the load unit are provided.

  A circuit block for monitoring charging is provided in the AC lines L1 and L2 on the external AC power supply AC side of the electromagnetic relay 11, which is a switch provided with relay contacts 111 and 112 interposed in the AC lines L1 and L2, respectively. A zero-phase current transformer (ZCT) 12 that is a current detection circuit, and a test electromagnetic relay 13 that is connected across the AC lines L1 and L2 and across the ZCT 12 are provided. Further, the circuit block for monitoring the charge is connected to the AC lines L1 and L2 on the input side of the plug P1 and connected to the external AC power supply AC, thereby generating a power supply voltage at a level required for each circuit unit. Confirmation of connection with the battery 53 (see FIG. 3) between the power supply circuit 21 and the load unit 50, for example, the charge control circuit 51 (see FIG. 3), an instruction for a test operation, and an exchange of a permission signal for starting charging Is connected to the control circuit 22, the leakage detection circuit 23 connected to the output side of the ZCT 12, the ground monitor 24, the AC lines L1 and L2 on the input side of the plug P2, and the voltage between the AC lines L1 and L2 is A voltage monitor 25 for detection and a test circuit 26 for performing a test operation are provided. Further, a sub-ground line S-GND branched from the ground line GND is input to the voltage monitor 25 through the ZCT 12 (primary side).

  The excitation coil 230 on the output side of the leakage detection circuit 23 is for stopping the current supply when the leakage is detected and returning the relay contacts 111 and 112 of the electromagnetic relay 11 from the closed state to the open state at once. At the start of charging, the relay contacts 111 and 112 are collectively switched from the open state to the closed state.

  When the control circuit 22 receives power supply from the power supply circuit 21, the control circuit 22 is activated to perform communication for confirming the connection of the load unit 50, for example, the charge control circuit 51, and to the test circuit 26 when the connection is confirmed. The test operation is instructed. When it is determined that the test operation is normal, the charging start is permitted. The test circuit 26 switches the test electromagnetic relay 13 to the closed state and shorts the AC lines L1 and L2 through the resistor R13 for a predetermined time. This short circuit causes an abnormality in the leakage detection circuit 23 as will be described later. When the occurrence of (leakage) is detected and the electromagnetic relay 11 is switched to the open state and the voltage monitor 25 detects that the voltage has disappeared between the AC lines L1 and L2 due to this switching, the leakage detection circuit 25, the electromagnetic This detection result is output to the control circuit 22 on the assumption that the relay 11 operates normally. Conversely, when the voltage monitor 25 detects an abnormality such as not detecting a voltage change, a signal indicating that there was an abnormality at the time of the test is output to the control circuit 22. The check in the voltage monitor 25 includes the presence or absence of welding of the relay contacts 111 and 112 of the electromagnetic relay 11, and details are shown in FIG. The control circuit 22 gives an instruction to start charging if it is normal, and rejects charging if it is abnormal.

  FIG. 2 is a detailed block diagram illustrating an example of the voltage monitor 25. In FIG. 2, the ZCT 12 is composed of a secondary winding (coil) wound around an annular core made of a ferromagnetic material such as permalloy, for example, and AC lines L1 and L2 and a sub-ground are arranged inside the annular. The line S-GND is inserted as the primary side. The sub ground line S-GND is branched between the plug P1 and the ZCT 12 in the middle of the ground line GND, and is used as a common line (ground) of the voltage monitor 25 as will be described later.

  The voltage monitor 25 is composed of first and second voltage monitor circuits 251 and 252, both of which basically have the same circuit configuration. The first voltage monitor circuit 251 cuts a DC component from an input signal, for example, a DC cut circuit 2511 made of a capacitor, a rectifier circuit 2512 that rectifies an input AC signal into a DC signal, and a rectified voltage signal A voltage detection circuit 2513 for detecting the level of the signal and a determination circuit 2514 for detecting or determining whether or not the detected voltage level exceeds a predetermined set value are connected in this order. Similarly, the second voltage monitor circuit 252 is also configured by connecting a DC cut circuit 2521, a rectifier circuit 2522, a voltage detection circuit 2523, and a determination circuit 2524 in this order.

  In the first voltage monitor circuit 251, the DC cut circuit 2511 is connected to the AC line L1 through the ZCT 12 and the switch 11, and the common side of each circuit unit is connected to the sub-ground line S-GND. . In the second voltage monitor circuit 252, the DC cut circuit 2521 is connected to the AC line L2 at a position through the ZCT 12 and the switch 11, and the common side of each circuit unit is connected to the sub-ground line S-GND. .

  Next, the welding state detection operation of the switch 11 by the voltage monitor 25 will be described. First, an instruction signal for opening the switch 11 is output from the test circuit 26. Specifically, the supply of the excitation current to the excitation coil 230 is stopped. If each relay contact 111, 112 operates normally (if it is not welded), both are open, and if not, at least one abnormal (welding) relay contact 111, 112 remains closed. .

  Next, the test circuit 26 outputs instructions for performing detection operations to the first and second voltage monitor circuits 251 and 252, respectively. In response to this instruction, the first and second voltage monitor circuits 251 and 252 start a detection operation, and output a determination result to the monitor circuit 26 according to the level of the detection voltage.

  If the relay contacts 111 and 112 of the switch 11 are both normal, no voltage is generated in the DC cut circuits 2511 and 2521. However, if a current corresponding to the stored charge flows in from any of potential difference absorbing capacitors C50, C51, and C52 described later in the load section 50 (see FIG. 3) having the plug TL, the current level depends on the current level. DC voltage will be generated. However, since the DC voltage is cut by the DC cut circuits 2511 and 2521, no output is output to the rectifier circuits 2512 and 2522. Therefore, even in such a case, the welding state detection of the switch 11 is normally performed.

  Next, if one of the relay contacts 111 and 112 of the switch 11 is welded, for example, the relay contact 111 is welded, a voltage is generated only in the DC cut circuit 2511 by the alternating current input through the alternating current line L1. . The generated voltage is rectified by the rectifier circuit 2512, the voltage level is detected by the voltage detection circuit 2513, and is determined to be abnormal by the determination circuit 2514 as exceeding a predetermined set level. Therefore, welding is detected with respect to the relay contact 111. Similarly, when both relay contacts 111 and 112 are welded, it is determined that both of the determination circuits 2514 and 2524 are abnormal. Therefore, in any case, the welding state detection for each relay contact of the switch 11 is normally performed. The voltage monitor circuits 251 and 252 adopt a configuration in which the DC component input to the DC cut circuits 2511 and 2521 is cut off, only the AC component is allowed to pass through, and fed back to the sub-ground line S-GND. Therefore, as will be described later, the number of flux linkages on the primary side line in the ZCT 12 can be balanced as compared with the case where the configuration is fed back to the ground line GND. As a result, the voltage monitor circuits 251 and 252 are present. Nevertheless, the normal operation of the leakage detection circuit 26 can be ensured. Note that the voltage detection circuits 2513 and 2523 may be digitally processed. Therefore, the determination circuits 2514 and 2524 may be determined by software using a microcomputer.

  Further, in FIG. 1, a leakage detection circuit 23 detects the presence or absence of abnormality during the charging operation, and details are shown in FIG.

  FIG. 3 is a detailed block diagram illustrating an example of the leakage detection circuit 23. In FIG. 3, first, the load unit 50 has a plug TL connected to the plug P2, and the AC line L1, L2, the ground line GND, and the control signal line can be connected to the load unit 50 through the plug TL. Has been. The load unit 50 includes an inverter-type known charge control circuit 51, a relay 52, and a chargeable / dischargeable battery (storage battery) 53. The output side from the battery 53 is not shown. The charging control circuit 51 can adopt various methods. For example, the voltage of the AC lines L1 and L2 is temporarily charged, switched at a high frequency to be converted into a predetermined DC voltage, and then supplied to the battery 53 via the relay 52. For example, the battery is charged with a current of about a dozen amperes. The relay 52 is for stopping the charging operation when fully charged.

  A capacitor C50 is connected between the AC lines L1 and L2, a capacitor C51 is connected between the AC line L1 and GND, and a capacitor C53 is connected between the AC lines L2 and GND. These capacitors C50, C51, and C52 are connected between the conversion voltage level in the charge control circuit 51 and the voltage levels of the AC lines L1 and L2 when the plug P2 and the plug TL are connected and the charging operation is started. It is for absorbing the difference. Further, by performing a switching operation at a high frequency in the charge control circuit 51, a high-frequency noise current flows, similarly, a potential difference is generated, and a noise current of each level flows in at least one of the capacitors. A current level difference is generated between the AC lines L1 and L2 of the charge monitoring device 1 due to the current as described above. Similarly, leakage between the AC lines L1 and L2 due to a power system line, a plug for each connection, a decrease in insulation around the battery 53, or a short circuit with a ground or other part having a voltage, etc. A current level difference occurs.

  The ZCT 12 detects such a difference in current level, and is generated by currents that are opposite to each other at normal 60 Hz flowing through the AC lines L1 and L2 and the sub-ground line S-GND at both ends of the coil (reverse directions). A voltage corresponding to the difference in the number of flux linkages is induced. Accordingly, while normal AC currents are flowing through the AC lines L1, L2 and the sub-ground line S-GND, the numbers of flux linkages in opposite directions are equal, the difference is zero, and there is no output. When a leakage current flows through one of the AC lines or when a current from another part is superimposed, the current level between the AC lines L1 and L2 is different, so that a differential voltage is generated at both ends of the coil. As described in FIG. 2, the AC lines L1. The AC current flowing in from L2 is reliably fed back through the sub-ground line S-GND by providing DC cut circuits 2511 and 2521 at the input stage of the voltage monitor circuits 251 and 252. Therefore, there is no false detection of leakage during charging.

  The mid-point ground circuit 231 functions as a voltage suppression circuit, and includes a series circuit composed of two resistors R1 and R2 having the same resistance value at both ends of the coil of the ZCT 12, and two capacitors C1 and C2 having the same capacitance value. Are connected in parallel, and the midpoints of the resistors R1 and R2 and the midpoints of the capacitors C1 and C2 are connected to the ground. The detected voltage of the coil is input to the differential amplifier circuit 232 via the midpoint ground circuit 231.

  The differential amplifier circuit 232 is composed of two operational amplifiers, each of which connects the terminal of the coil of the ZCT 12 to the input terminal, amplifies the difference from the ground of the other input terminal, and outputs the difference. It is something to get. In the mode in which the difference is amplified and output by one operational amplifier, the offset voltage of the amplifier affects the differential voltage and may contain an error, but two operational amplifiers are used in parallel. Thus, both offset voltages are canceled out, and the difference in input voltage with respect to zero potential is amplified, so that high accuracy can be ensured.

    The low-pass filter 233 is a filter that takes into account the frequency characteristics of the leakage current. This filter is used when the leakage current includes multiple frequencies. Its frequency and signal attenuation characteristics are matched to the perception threshold, and the sensitivity is higher at lower frequencies, and the sensitivity is lower at higher frequencies. As described above, the values of the circuit elements are set. The DC cut filter 234 blocks a DC component from a differential voltage detected based on a temporary transient current other than leakage that is superimposed on the AC lines L1 and L2, and is typically used for cutting a DC component. Consists of capacitors. The rectifying / smoothing circuit 235 rectifies the output signal of the DC cut filter 234, further smoothes it, and outputs it. Since the DC component is cut by the DC cut filter 234 in the rectifying operation of the rectifying / smoothing circuit 235, a full-wave rectification circuit configuration can be obtained, and the DC component can be suppressed by using full-wave rectification. After that, sensitivity and responsiveness can be increased. The determination circuit 236 is configured as a comparison circuit that compares the level of the input signal with a preset reference level. When the input signal level exceeds the reference level, it is considered that leakage has occurred and is sent to the excitation coil 230. Is stopped, and the electromagnetic relay 11 is switched from the closed state during charging to the open state at the time of abnormality. Note that the determination circuit 236 may convert the input signal into a digital signal and perform comparison determination processing by software using a microcomputer.

  Moreover, although this embodiment demonstrated the example of single phase 200V alternating current and 60 Hz, this invention is applicable to various external alternating current power supplies (voltage, frequency). In addition, the present invention is applied to a battery charging system for an automobile or an electric vehicle having two power sources of an engine and an electric motor, a battery storage system for household and electric equipment, a power storage system for solar power generation and wind power generation, and the like. Is also applicable.

It is a block diagram which shows one Embodiment at the time of applying the charge monitoring apparatus which concerns on this invention to a charging device provided with a storage battery (battery). It is a detailed block diagram showing an example of a voltage monitor. It is a detailed block diagram showing an example of a leakage detection circuit.

Explanation of symbols

1 Charge monitoring device 11 Electromagnetic relay (switch)
111, 112 Relay contact 12 Zero-phase current transformer (current detection circuit)
DESCRIPTION OF SYMBOLS 23 Leakage detection circuit 230 Excitation coil 231 Mid-point ground circuit 232 Differential amplification circuit 233 Low-pass filter 234 DC cut filter 235 Rectification smoothing circuit 236 Determination circuit 25 Voltage monitor (contact state detection means)
2511, 2521 DC cut circuit 2512, 2522 Rectifier circuit 2513, 2523 Voltage detection circuit 2514, 2524 Determination circuit 26 Test circuit (part of contact state detection means)
L1, L2 AC line GVD Ground line S-GND Sub-ground line P1, P2 Plug

Claims (2)

A switch having a relay contact interposed between an external AC power source and a ground battery from the external AC power source and a storage battery charged via the two AC lines, and individually opens and closes the two AC lines. In the charge monitoring device with
Contact state detecting means for detecting the occurrence of voltage between each AC line and the sub-ground line branched from the ground line on the storage battery side of the switch in a state in which the switch is in the open state. When,
It has a zero-phase current transformer that detects the difference between the levels of the currents flowing through the two AC lines and the sub-ground line on the external AC power supply side of the switch, and determines that there is a leakage if there is a difference. A charge monitoring apparatus comprising: a leakage detection means.   2. The charge monitoring apparatus according to claim 1, wherein the contact state detecting means has a DC component blocking circuit for blocking a DC component at an input stage thereof.

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