JP2013109943A - Latching relay control circuit and watt-hour meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a latching relay control circuit and a watt-hour meter capable of drastically reducing high-withstanding voltage elements without using a DC power supply for driving a latching relay.SOLUTION: A latching relay control circuit has: a switch connected with both ends of a series circuit in which an AC power supply and a latching relay drive coil are connected; a voltage detector detecting an AC voltage of the AC power supply; an open/close signal output part outputting an open signal or a close signal to the latching relay drive coil; and a switch controller turning on the switch on the basis of the AC voltage detected by the voltage detector, a first voltage threshold to be compared with the AC voltage when the open signal is input from the open/close signal output part, and a second voltage threshold to be compared with the AC voltage when the close signal is input.

Description

  The present invention relates to a latching relay control circuit used in a watt-hour meter and a watt-hour meter using the latching relay control circuit.

  The watt-hour meter measures the power from the power supply facility, and the latching relay control circuit turns on the latching relay to supply the power to the load.

  FIG. 18 is a diagram illustrating an example of a conventional latching relay control circuit. The latching relay control circuit shown in FIG. 18 includes a DC power supply Vd, switches SW1 to SW4, and a latching relay drive coil L1 having a resistance R1. The switch SW1 and the switch SW4 are simultaneously turned on by the open signal, the DC power source Vd is applied to the latching relay drive coil L1, and the switch SW2 and the switch SW3 are simultaneously turned on by the close signal, and the DC is applied to the latching relay drive coil L1. The latching relay can be driven by applying the power supply Vd.

  FIG. 19 is a diagram illustrating another example of a conventional latching relay control circuit. The latching relay control circuit shown in FIG. 19 includes a first series circuit including a latching relay drive coil L1 having a resistor R1 and a switch SW1, and a second series circuit including a latching relay drive coil L2 having a resistor R2 and a switch SW2. Are connected in parallel to the DC power source Vd. When the switch SW1 is turned on by the open signal, the DC power source Vd is applied to the latching relay drive coil L1, and when the switch SW2 is turned on by the close signal, the DC power source Vd is applied to the latching relay drive coil L2, thereby enabling the latching relay. It can be driven.

  Further, for example, Patent Documents 1 and 2 are known as conventional techniques. Patent Document 1 monitors a capacitor that accumulates energy from Vcc when a relay drive power supply Vcc is applied, and determines whether the energy accumulated in the capacitor is greater than or equal to a predetermined value by monitoring the voltage of the capacitor. A voltage monitoring unit, a first transistor that is turned on when it is determined that the energy accumulated in the capacitor is equal to or greater than a predetermined value, a second transistor that is turned on when Vcc is cut off, and a set coil and a reset coil. A latching relay that is set by flowing current from Vcc to the set coil when the first transistor is turned on, and reset by flowing current from the capacitor to the set coil when the second transistor is turned on, The relay switch can be switched on and off reliably.

  In Patent Document 2, the hybrid relay includes a latching-type first mechanical contact switch having a contact portion whose both ends are connected to a terminal, and a second magnetic that is separate from the first magnetic coil of the first mechanical contact switch. The first mechanical contact switch having a coil is provided, and the second mechanical contact switch and the semiconductor switch are turned on only when the first mechanical contact switch is switched on / off.

JP 2006-179232 A JP 2010-103099 A

  However, the latching relays shown in FIGS. 18 and 19 and Patent Documents 1 and 2 require a large DC power supply of about several watts to drive the relay. For this reason, in the watt-hour meter which has the conventional latching relay, it was necessary to provide the big DC power supply Vd for driving a relay.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a latching relay control circuit and a watt hour meter that can significantly reduce high withstand voltage elements without using a DC power source for driving a latching relay.

  In order to solve the above problems, a latching relay control circuit according to the present invention detects a switch connected to both ends of a series circuit in which an AC power supply and a latching relay drive coil are connected, and an AC voltage of the AC power supply. A voltage detection unit, an open / close signal output unit that outputs an open signal or a close signal to the latching relay drive coil, an AC voltage detected by the voltage detection unit, and the open signal from the open / close signal output unit And a switch control unit that turns on the switch based on a first voltage threshold value to be compared with the AC voltage and a second voltage threshold value to be compared with the AC voltage when the closed signal is input. And

  Moreover, the watt-hour meter which concerns on this invention is provided with the latching relay control circuit of any one of Claims 1 thru | or 7.

  According to the present invention, high voltage elements can be significantly reduced without using a DC power supply for driving a latching relay.

It is a block diagram which shows the structure of the watt-hour meter which has a latching relay control circuit which concerns on Example 1 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 1 of this invention. It is a flowchart which shows operation | movement when a closing signal is applied to a latching relay by the latching relay control circuit which concerns on Example 1 of this invention. It is a wave form diagram of each part when a closing signal is applied to a latching relay by the latching relay control circuit concerning Example 1 of the present invention. It is a flowchart which shows operation | movement when an open signal is applied to a latching relay by the latching relay control circuit which concerns on Example 1 of this invention. It is a wave form diagram of each part when an open signal is applied to a latching relay by the latching relay control circuit which concerns on Example 1 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 2 of this invention. It is a wave form diagram of each part of the latching relay control circuit which concerns on Example 2 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 3 of this invention. It is a wave form diagram of each part of the latching relay control circuit which concerns on Example 3 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 4 of this invention. It is a figure which shows the operation | movement of the filter of the latching relay control circuit which concerns on Example 4 of this invention. It is a flowchart which shows the operation | movement of the filter of the latching relay control circuit which concerns on Example 4 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 5 of this invention. It is a flowchart which shows operation | movement of the latching relay control circuit which concerns on Example 5 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 6 of this invention. It is a figure which shows the latching relay control circuit which concerns on Example 7 of this invention. It is a figure which shows an example of the conventional latching relay control circuit. It is a figure which shows another example of the conventional latching relay control circuit.

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

  FIG. 1 is a block diagram illustrating the configuration of the watt-hour meter having the latching relay control circuit according to the first embodiment. This watt-hour meter 3 includes an input terminal 30 connected to the power supply facility 1 via the power line 2, an output terminal 31 connected to the load 4, a current detection unit 32, a voltage detection unit 33, a latching relay 34, relay control. A circuit 35, a central processing unit 36, a display unit 37, a nonvolatile memory 38, and a communication connector 39 are provided.

  The current detection unit 32 detects the use current (A1) used in the load 4 of the consumer, converts it into an electrical signal corresponding to the use current, and outputs it. The voltage detector 33 is a part for detecting the voltage of the system under measurement, and is constituted by a voltage dividing resistor such as a voltage transformer or an attenuator, etc., and a working voltage (V1) used at the customer load 4 Is detected, converted to a low level voltage signal that is directly proportional to the operating voltage, and output.

The power calculation unit 36 is configured by a digital multiplication circuit, a DSP (digital signal processor), and the like, and calculates the amount of power based on the current detected by the current detection unit 32 and the voltage detected by the voltage detection unit 33. . The display unit 37 is composed of a liquid crystal display or the like and displays usage data.
The relay control circuit 35 connects the input terminal 30 and the output terminal 31 by driving the latching relay 34 to supply power from the power supply facility 1 to the load 4. The nonvolatile memory 38 stores the usage data calculated by the power calculation unit 36. The communication connector 39 is a connector for performing communication between the watt-hour meter 3 and the outside.

  FIG. 2 is a diagram illustrating the latching relay control circuit according to the first embodiment of the invention. In the relay control circuit shown in FIG. 2, a switch SW is connected to both ends of a series circuit in which a latching relay drive coil L1 having a resistor R1 and an AC power source Vs are connected, and a voltage detection unit 341, an open / close signal output unit 342, a switch A control unit 343 is included.

  The voltage detection unit 341 detects the AC voltage of the AC power supply Vs and outputs the detected voltage to the switch control unit 343. The open / close signal output unit 342 outputs a close signal for closing the latching relay and outputs an open signal for opening the latching relay.

  The switch control unit 343 includes a central processing unit (CPU) and the like, and includes a detection voltage detected by the voltage detection unit 341, an open signal or a close signal from the open / close signal output unit 342, and a first voltage when the close signal is applied. The switch SW is turned on based on the threshold value VTH1 and the second voltage threshold value VTH2 when the open signal is applied.

  Next, the operation of the latching relay control circuit according to the first embodiment configured as described above will be described with reference to the flowchart shown in FIG. FIG. 3 is a flowchart showing an operation when a closing signal is applied to the latching relay by the latching relay control circuit according to the first embodiment of the present invention.

  First, when a close signal output command is issued, a close signal is output from the open / close signal output unit 342 to the switch control unit 343. The voltage threshold detection flag VTFG is set to “0” (step S11). The AC voltage of the AC power source Vs is measured by the voltage detection unit 341 (step S12).

  Next, the switch control unit 343 determines whether or not the actual measurement value Vi of the AC power supply Vs is greater than the first voltage threshold value VTH1 (step S13). When the actual measurement value Vi is smaller than the first voltage threshold value VTH1, the voltage threshold value detection flag VTFG is set to “1” (step S14), and the process returns to step S12.

  The switch control unit 343 determines whether or not the voltage threshold detection flag VTFG is “1” (step S15). If the voltage threshold detection flag VTFG is not “1”, the process returns to step S12. If the voltage threshold detection flag VTFG is “1”, the switch SW is turned on (step S16). As a result, as shown in FIG. 4, a positive current i flows through the drive coil L1. FIG. 4 shows the AC voltage Vs of the AC power supply.

  Next, the AC voltage of the AC power source Vs is measured by the voltage detector 341 (step S17). The switch controller 343 determines whether or not the actual measurement value Vi of the AC power supply Vs is smaller than the first voltage threshold value VTH1 (step S18). When the actual measurement value Vi is larger than the first voltage threshold value VTH1, the process returns to step S17.

  When the actual measurement value Vi is smaller than the first voltage threshold value VTH1, the switch SW is turned off (step S19, time t1 in FIG. 4).

  Next, the operation when the closing signal is applied to the latching relay by the latching relay control circuit according to the first embodiment will be described with reference to the flowchart shown in FIG.

  First, when an open signal output command is issued, an open signal is output from the open / close signal output unit 342 to the switch control unit 343. The voltage threshold detection flag VTFG is set to “0” (step S21). The AC voltage of the AC power source Vs is measured by the voltage detector 341 (step S22).

  Next, the switch control unit 343 determines whether or not the actual measurement value Vi of the AC power supply Vs is smaller than the second voltage threshold value VTH2 (step S23). When the actual measurement value Vi is larger than the second voltage threshold value VTH2, the voltage threshold value detection flag VTFG is set to “1” (step S24), and the process returns to step S22.

  The switch control unit 343 determines whether or not the voltage threshold detection flag VTFG is “1” (step S25). If the voltage threshold detection flag VTFG is not “1”, the process returns to step S22. If the voltage threshold detection flag VTFG is “1”, the switch SW is turned on (step S26). As a result, as shown in FIG. 6, a negative current i flows through the drive coil L1. FIG. 6 shows the AC voltage Vs of the AC power supply.

  Next, the AC voltage of the AC power source Vs is measured by the voltage detector 341 (step S27). The switch control unit 343 determines whether or not the actual measurement value Vi of the AC power supply Vs is greater than the second voltage threshold value VTH2 (step S28). When the actual measurement value Vi is smaller than the second voltage threshold value VTH2, the process returns to step S27.

  When the actual measurement value Vi is larger than the second voltage threshold value VTH2, the switch SW is turned off (step S29, time t2 in FIG. 6).

  Thus, according to the latching relay control circuit according to the first embodiment, the voltage detection unit 341 monitors the AC voltage of the AC power supply Vs, and compares the detected AC voltage with a plurality of voltage thresholds VTH1 and VTH2. By turning on the switch SW, the voltage applied to the latching relay drive coil can be controlled to drive the latching relay.

  Therefore, it is possible to efficiently apply voltage or current from the AC power source to the latching relay drive coil without using a DC power source, a rectifying unit, or a plurality of switches.

  FIG. 7 is a diagram illustrating a latching relay control circuit according to the second embodiment of the present invention. In the latching relay control circuit shown in FIG. 7, a switch SW is connected to both ends of a series circuit in which a latching relay drive coil L1 having a resistor R1 and an AC power supply Vs are connected, and a voltage detection unit 341, a timer 344, and a switch control unit. 343.

  The timer 344 sets a time necessary for applying a plurality of currents to the latching relay drive coil L1 from the time of zero crossing of the voltage detected by the voltage detection unit 341. The switch control unit 343 turns on the switch SW only for the time set by the timer 344 only when the voltage detected by the voltage detection unit 341 is positive.

  FIG. 8 is a waveform diagram of each part of the latching relay control circuit according to the second embodiment of the present invention. As shown in FIG. 8, when the AC voltage detected by the voltage detector 341 is a positive voltage and the switch SW is turned on for the time set by the timer 344, the coil current i flows.

  As described above, according to the latching relay control circuit according to the second embodiment, the time set by the timer 344 is required when it is necessary to apply a plurality of currents due to the influence of the power supply voltage condition, the condition of the latching relay drive coil, and the like. Only the coil current can be applied multiple times or intermittently.

  A counter may be used instead of the timer, and the coil current can be applied a plurality of times or intermittently by the number of times set by the counter.

  FIG. 9 is a diagram illustrating a latching relay control circuit according to the third embodiment of the present invention. The latching relay control circuit according to the third embodiment illustrated in FIG. 9 includes a latching relay drive coil L1 having a resistor R1, an AC power supply Vs, a triac SWa, a voltage detection unit 341, a timer 344, and a switch control unit 343.

  The voltage detector 341 detects the AC voltage of the AC power supply Vs, and detects the detected zero cross of the AC voltage as shown in FIG. The timer 341 sets the operation time of the triac SWa. As shown in FIG. 10, the switch control unit 343 turns on the triac SWa for a time set by the timer 341 from the zero cross of the voltage detection unit 341. For this reason, a coil current i consisting of a complete half-wave flows.

  Therefore, also in the latching relay control circuit according to the third embodiment, the same effect as that of the latching relay control circuit according to the second embodiment can be obtained.

  FIG. 11 is a diagram illustrating a latching relay control circuit according to the fourth embodiment of the present invention. The latching relay control circuit according to the fourth embodiment illustrated in FIG. 11 includes a filter 401 and a detection unit 403 for preventing a malfunction (hardware or software) in the voltage detection unit of the latching relay control circuit according to the third embodiment. A voltage detection unit 341a including the above is provided.

  The detection unit 403 detects the AC voltage of the AC power supply Vs. The filter 401 has an A / D 402 that converts an analog signal into a digital signal.

  The filter 401 converts the AC voltage signal detected by the detection unit 403 into an AD conversion value. The filter 401 performs the following determination to prevent erroneous determination due to noise or the like. When the AD conversion value (AC voltage signal shown in FIG. 12) is positive (including 0), the counter shown in FIG. 12 is incremented by one. If the AD conversion value is negative, the counter is decremented by -1. When the counter value reaches the first set value N1 (N1 = 5 in the example shown in FIG. 12), it is in a plus (+) state, and the counter value is the second set value N2 (N2 = 0 in the example shown in FIG. 12). ), A negative (-) state is assumed.

  As shown in FIG. 12, when the signal is “+”, the counter is “5” and the state is “+”. When the signal changes from “+” to “−”, the counter becomes “4”, “3”, “2,“ 1 ”, and the state is“ + ”. The state changes from “+” to “−”, and a positive to negative zero cross is detected.

  When the signal is “−”, the counter is “0” and the state is “−”. When the signal changes from “−” to “+”, the counter becomes “1”, “2”, “3,“ 4 ”, and the state is“ − ”. The state changes from “−” to “+”, and a negative to positive zero cross is detected, and when the signal is “+”, the counter is “5” and the state is “+”.

  In this way, by providing a step for zero cross detection, it is possible to prevent a malfunction of the latching relay that occurs when voltage fluctuation due to pulse noise or the like instantaneously crosses the zero cross.

  FIG. 13 is a flowchart showing the operation of the filter of the latching relay control circuit according to the fourth embodiment of the present invention. Each process shown in FIG. 13 is used when each process shown in FIG. 12 is performed.

  The zero cross detection flag ZCFG is any one of “−1”, “0”, and “1”, “−1” indicates detection of a positive to negative zero cross, and “1” indicates a negative to positive zero cross. Indicates detection. The state flag STS is either “0” or “1”, “0” indicates that the state is “−”, and “1” indicates that the state is “+”.

  First, when zero-cross detection is started, the zero-cross detection flag ZCFG is set to “0” (step S31).

  Next, it is determined whether or not the AC voltage signal Vi is negative (step S32). If the AC voltage signal Vi is negative and the counter J is positive, the counter J is set to “−1” (step S32). S34). Further, it is determined whether or not the counter J is “0” (step S35). If the counter J is “0”, it is determined whether or not the status flag STS is “1” (step S36). If the status flag STS is “1”, the zero cross detection flag ZCFG is set to “−1” (step S37), and the status flag STS is set to “0”.

  On the other hand, if the AC voltage signal Vi is positive in step S32, it is determined whether the counter J is smaller than N (= 5) (step S39), and if the counter J is smaller than N (= 5). The counter J is incremented by 1 (step S40). If the counter J is greater than or equal to N, it is determined whether or not the status flag STS is “0” (step S42). If the status flag STS is “0”, the zero cross detection flag ZCFG is set to “1” (step S43), and the status flag STS is set to “1”.

  FIG. 14 is a diagram illustrating a latching relay control circuit according to the fifth embodiment of the present invention. The latching relay control circuit according to the fifth embodiment shown in FIG. 14 has a correction unit 405 that corrects the set time 406 that the timer 344a should apply to the drive coil with respect to the timer 344 shown in FIGS. Features.

  Although the voltage and current applied to the driving coil of the latching relay change due to the influence of the power supply voltage conditions (power supply frequency, voltage value, etc.) and the number of relays to be controlled, the correction unit 405 The set time 406 to be applied to the drive coil is corrected according to the number of relays. Therefore, it is possible to prevent malfunction due to the above-described influence.

  Further, when the timer 344a measures a certain time, the switch control unit 343 turns off the switch SW, so that long time continuous voltage and current application to the drive coil can be prevented.

  FIG. 15 is a flowchart showing the operation of the latching relay control circuit according to the fifth embodiment of the present invention. It is determined whether or not the AC power supply Vs is on (step S51). If the AC power supply Vs is on, the counter C is incremented by 1 (step S52). When the counter C exceeds the set time T, the open / close signal Vs is turned off (step S54), and the counter C is set to “0” (step S55).

  FIG. 16 is a diagram illustrating a latching relay control circuit according to the sixth embodiment of the present invention. In FIG. 16, a parallel circuit of a series circuit of a diode D1 and a switch SW1 and a series circuit of a diode D2 and a switch SW2 is connected to both ends of a series circuit of an AC power supply Vs and a latching relay L1. The anode of the diode D1 and the cathode of the diode D2 are connected to one end of the AC power supply Vs.

  The timer 344 sets the operation time of the switches SW1 and SW2. The switch SW1 applies an open signal to the latching relay drive coil L1. The switch SW2 applies a close signal to the latching relay drive coil L1. The switch control unit 343 turns on the switch SW1 and the switch SW2 for the time set by the timer 344.

  As described above, according to the latching relay control circuit according to the sixth embodiment, the switch control unit 343 turns on the switch SW1 and the switch SW2 only for the time set by the timer 344. Therefore, for the time set by the timer 344, The AC power source of the AC power source Vs can be applied to the latching relay drive coils L1 and L2 to drive the latching relay. Therefore, the latching relay can be driven without using a large-capacity DC power source for driving the latching relay.

  FIG. 17 is a diagram illustrating a latching relay control circuit according to the seventh embodiment of the present invention. The latching relay control circuit according to the seventh embodiment shown in FIG. 17 has a bridge rectification unit including diodes D3 to D6 for full-wave rectification of the AC voltage of the AC power supply Vs, and a diode D3 and a diode that are outputs of the bridge rectification unit Between the connection point of D4 and the connection point of the diode D5 and the diode D6, a series circuit of the switch SW1 and the latching relay drive coil L1 and a series circuit of the switch SW2 and the latching relay drive coil L2 are in parallel. It is connected.

  As described above, according to the latching relay control circuit according to the seventh embodiment, the switch control unit 343 turns on the switch SW1 and the switch SW2 only for the time set by the timer 344. Therefore, only for the time set by the timer 344, The rectified voltage from the bridge rectifier can be applied to the latching relay drive coils L1, L2 to drive the latching relay. Therefore, the latching relay can be driven without using a large-capacity DC power source for driving the latching relay.

DESCRIPTION OF SYMBOLS 1 Power supply equipment 2 Power line 3 Wattmeter 4 Load 30 Input terminal 31 Output terminal 32 Current detection part 33 Voltage detection part 34 Latching relay 35 Relay control circuit 36 Central processing part 37 Display part 38 Non-volatile memory 39 Communication connectors 341 and 341a Voltage detection unit 342 Open / close signal output unit 343 Switch control unit 344 Timer 344a Counter 401 Filter 402 A / D
403 Detection unit 405 Correction unit Vs AC power supply L1, L2 Latching relay drive coil R1, R2 Resistance D1-D6 Diode SW, SW1, SW2 Switch SWa Triac

Claims (8)

A switch connected to both ends of a series circuit to which an AC power supply and a latching relay drive coil are connected;
A voltage detector for detecting an AC voltage of the AC power source;
An open / close signal output unit for outputting an open signal or a close signal to the latching relay drive coil;
The AC voltage detected by the voltage detector and the AC voltage when the closed signal is input as a first voltage threshold value compared with the AC voltage when the open signal is input from the switching signal output unit. A switch controller that turns on the switch based on a second voltage threshold compared to
A latching relay control circuit comprising: A timer for setting a time necessary for applying a plurality of currents to the latching relay drive coil based on the voltage threshold detected by the voltage detector;
The latching relay control circuit according to claim 1, wherein the switch control unit outputs the open signal or the close signal for a time set by the timer.   The latching relay control circuit according to claim 1, wherein the switch is a triac.   The voltage detector increments the counter value when the detected voltage value is positive, decrements the counter value when the voltage value is negative, and increases when the counter value becomes the first set value. 4. The filter according to claim 1, further comprising a filter that sets a negative state when the state and the counter value become the second set value, and provides stepping for the zero cross detection of the voltage. The latching relay control circuit described.   5. The timer includes a correcting unit that corrects the set time according to at least one of a condition of a power supply voltage of the AC power supply and the number of latching relay drive coils. A latching relay control circuit according to claim 1. A first series circuit in which an AC power source and a latching relay drive coil are connected;
A second series circuit connected to both ends of the first series circuit and connected to a first switch for applying an open signal to the latching relay drive coil;
A third series circuit connected to both ends of the first series circuit and connected to a second diode and a second switch for applying a closing signal to the latching relay drive coil;
A timer to set the time,
A switch control unit for turning on the first switch and the second switch for a time set by the timer;
A latching relay control circuit comprising: A rectifier that rectifies the AC voltage of the AC power supply;
A first series circuit connected to both ends of the output of the rectifying unit and connected to a first switch and a first latching relay drive coil;
A second series circuit connected to both ends of the output of the rectifying unit and connected to a second switch and a second latching relay drive coil;
A timer to set the time,
A switch control unit for turning on the first switch and the second switch for a time set by the timer;
A latching relay control circuit comprising:   A watt-hour meter comprising the latching relay control circuit according to claim 1.

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