JP7096471B2 - Current measuring device, disconnection detection device and current measuring method - Google Patents

Description

The present invention relates to a current measuring device for measuring a current in a power supply path to a plurality of loads, a disconnection detecting device provided with the current measuring device, and a current measuring method.

In various electric and electronic circuits, the current at a predetermined position is measured in the processing operation, and a current measuring circuit for that purpose is provided.
One example of the purpose of current measurement is to detect a disconnection or short circuit in the power supply path to the load.

Japanese Unexamined Patent Publication No. 04-26091 Japanese Unexamined Patent Publication No. 2001-255945

As exemplified in Patent Document 1 and Patent Document 2, in a device having a plurality of loads (heaters), it may be desired to individually detect a disconnection or a short circuit in the power supply path of each load. In such a device, Patent Document 1 consolidates the configurations for detecting disconnection into one. That is, as shown in FIGS. 1 and 2 of Patent Document 1, the inputs from the plurality of current detecting means 104 (heater current detecting circuits) are switched and input to the heater adiabatic detecting means 105 (control means 41). Therefore, the configuration for detecting the disconnection is integrated in the heater adiabatic detection means 105 (control means 41). By consolidating the configurations for detecting disconnection into one in this way, cost reduction and space saving can be achieved.
In the technique of Patent Document 1, "the detection signal of the heater means 101 being operated by the heater operating means 102 is taken in from the one in which the heater current measuring conditions are satisfied, and when the value is lower than a predetermined reference value, the heater to the heater means 101 is taken in. It detects that the circuit is broken (upper left column of item 3). Here, the "heater current measurement condition is satisfied" in Patent Document 1 is determined on the premise that the output ON / OFF period is known (paragraph 5, upper left column). That is, the information of the output ON / OFF period is input to the main body (microcomputer, etc.) that performs the process of switching the input from the plurality of current detecting means 104 (heater current detection circuit) and the process of measuring the heater current. However, such restrictions have one aspect of reducing the degree of freedom in designing the device.
For example, when considering the design of the entire device, information on the output ON / OFF period for the main body (microcomputer, etc.) for switching the inputs from multiple current detection means and processing the current measurement of each load. In some cases, it is not efficient to input, and in such cases, conventional techniques cannot handle it.

In view of the above points, the present invention provides a current measuring device for measuring each current in a power supply path for each of a plurality of loads, and providing a current measuring device for measuring current by a method not conventionally used. With the goal.

(Structure 1)
A current measurement signal selection output unit that switches and outputs a current measurement signal from a current measuring device provided in each of the power supply paths for each of the plurality of loads, and an output on signal or output of power supply for each of the plurality of loads. A stable state determination unit that uses a load that receives an off signal and continues to receive the output on signal or output off signal for a predetermined time or longer as a stable state load, and a load that is determined to be the stable state load. A current that receives a current measurement signal corresponding to a measurable unmeasured load whose current value is unmeasured from the current measurement signal selection output unit, measures the current, and makes the measured load already measured. A current measuring device including a measuring unit.

(Structure 2)
Priority information is associated with the load, and when there are a plurality of measurable unmeasured loads, the current of the load having the highest priority is measured based on the priority information. The current measuring device according to 1.

(Structure 3)
An on-measurable unmeasured load in which the output on signal is a stable state load that has continued for a predetermined time or longer and a current value has not been measured, and a stable state load in which the output off signal has continued for a predetermined time or longer and a current. The current measuring apparatus according to configuration 1 or 2, wherein when an off-measurable unmeasured load whose value is unmeasured is simultaneously present, the current measurement of the on-measurable unmeasured load is preferentially performed.

(Structure 4)
If there is no measurable unmeasured load and there is a measurable measured load that is determined to be the stable state load and the current value has been measured, the current measurement of the measurable measured load is performed. The current measuring device according to any one of configurations 1 to 3, characterized in that.

(Structure 5)
If the measurable unmeasured load occurs during the current measurement of the measurable measured load, the current measurement of the measurable measured load shall be stopped and the current measurement of the measurable unmeasured load shall be performed. 4. The current measuring device according to the configuration 4.

(Structure 6)
The current measuring device according to any one of configurations 1 to 5, wherein when all the current values of the plurality of loads have been measured, all the loads have not been measured.

(Structure 7)
The current measuring device according to any one of configurations 1 to 6, wherein all loads are not measured after a lapse of a predetermined period.

(Structure 8)
It is equipped with an internal reference value capture unit that captures the A / D count value at the LOW level or HIGH level of the signal circuit.
The current measuring device according to any one of configurations 1 to 7, wherein when there is no load determined to be a stable state load, the internal reference value acquisition unit performs an acquisition process.

(Structure 9)
When the capture process is performed by the internal reference value capture unit, it is assumed that the internal reference value has been captured, and the current values of all the loads have been measured and the internal reference value has been captured. The current measuring device according to the configuration 8, wherein all the loads are unmeasured and the internal reference value is not taken in.

(Structure 10)
A disconnection detection device including the current measuring device according to any one of configurations 1 to 9.

(Structure 11)
A step of receiving an output on signal or an output off signal of power supply for each of a plurality of loads, and setting a load in which the output on signal or the output off signal is received for a predetermined time or longer as a stable state load. A current characterized by comprising a step of measuring the current of a load which is determined to be a stable state load and whose current value has not been measured, and making the measured load already measured. Measuring method.

In the current measuring device of the present invention, a load in which the period of receiving the output on signal or the output off signal continues for a predetermined time or longer is determined to be a stable state, and the load is in a stable state and has not been measured. Since the current is measured from the beginning, processing can be performed even if there is no information on the output on / off period.

A block diagram showing an outline of a system configuration including a current measuring device according to an embodiment of the present invention. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. A flowchart showing an outline of the processing operation of the current measuring device of the embodiment. Timing diagram for explaining the operation of the current measuring device of the embodiment Timing diagram for explaining the operation of the current measuring device of the embodiment Timing diagram for explaining the operation of the current measuring device of the embodiment

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It should be noted that the following embodiment is an embodiment of the present invention and does not limit the present invention to the scope thereof.

FIG. 1 is a block diagram showing an outline of a system configuration including a current measuring device according to an embodiment of the present invention.
The system controls the temperature of a device having a plurality of loads (heaters) with a plurality of heaters 6 as control targets. Although only one of the power supply circuit parts to the load (heater) is drawn in FIG. 1 for simplification, a plurality of parts surrounded by dotted lines (16 channels in this embodiment) are provided. Is.
As shown in FIG. 1, a switching element that switches power supply on / off on a power supply path of a heater 6 that is a load and an AC power supply 5 that supplies power to the heater 6 (in this embodiment, a solid state relay (solid state relay (in this embodiment)). SSR)) 21 and a current measuring device (current transformer (CT) 22 in this embodiment) are provided.
The system of FIG. 1 controls the temperature by controlling the power supply to the heater 6 by controlling the on / off of the switching element (SSR) 21 based on the time proportional control. In the system of FIG. 1, as a rough configuration thereof, an output controller 1 that controls the SSR 21 and the like, an output controller 2 equipped with the above-mentioned SSR 21 and CT 22, and an on / off control of the SSR 21 by feedback control such as PID are performed. A temperature controller 3 for calculating a control signal and the like, and a communication device 4 for communicating with a higher-level device and the like are provided.

The SSR 21 and CT 22 mounted on the output device 2 are provided for 16 channels as described above. Each SSR 21 is connected to the microcomputer 11 mounted on the output controller 1 by wiring for 16 channels. On the other hand, each CT 22 is connected to a current measurement signal selection output unit (multiplexer (MUX) in this embodiment) 12, and by connecting the MUX 12 and the microcomputer 11, the MUX 12 is switched by the control from the microcomputer 11, which is desired. The signal from CT22 of the channel is input to the microcomputer 11.
The output device 2 is provided with an internal reference value acquisition unit 23. The internal reference value acquisition unit 23 captures the A / D count value at the LOW level or HIGH level of the signal circuit of the output device 2, and each signal is calibrated based on the A / D count value. Is.
In the microcomputer 31 of the temperature controller 3, the temperature information (PV) obtained by the temperature sensor 7 provided in the vicinity of the controlled object whose temperature is controlled by the heater 6 and the target temperature obtained via the microcomputer 41 of the communication device 4 The operation amount (MV) is calculated based on the information (SV), the output on signal and the output off signal are calculated based on the operation amount (MV), and the process of outputting this to the microcomputer 11 of the output controller 1 is performed. Further, the microcomputer 31 of the temperature controller 3 also performs disconnection alarm processing, short circuit (welding) alarm processing, etc. based on the current value information (based on the signal from each CT 22) obtained from the microcomputer 11 of the output controller 1. Will be.
Although the description of each in each place is omitted, the analog signal (signal from CT22, temperature sensor 7, etc.) is A / D converted and then input to each microcomputer.

The present invention mainly relates to a portion for measuring currents flowing through a plurality of loads, and is mainly implemented in the output controller 1 in the present embodiment. When focusing on the function of current measurement, the output controller 1 functions as a current measuring device.
The microcomputer 11 provided in the output controller 1 receives an output on signal or an output off signal of power supply for each of the plurality of loads (heaters 6) from the microcomputer 31 of the temperature controller 3, and the output on signal or the output off signal is received. The function of discriminating the heater 6 whose signal reception period has continued for a predetermined time or longer as a stable state load, and the heater 6 determined to be the stable state load, and the current value measurement flag has not been measured. It has a function of receiving a current measurement signal corresponding to a measurable unmeasured load from the MUX 12, measuring the current, and setting the current value measurement flag corresponding to the heater 6 for which the current measurement has been measured. That is, the microcomputer 11 has a function as a current measuring unit and a stable state determination unit.

Next, the processing operation portion according to the present invention in the system of FIG. 1 having the above configuration will be described with reference to the flowcharts of FIGS. 2 to 9 and the timing diagrams of FIGS. 10 to 12. In the following description, the processing subject is omitted, but the following processing is executed by the microcomputer 11 of the output controller 1.

2 to 4 are flowcharts showing an example of a process of determining whether or not each load (heater 6) is a stable state load, and the processes of FIGS. 3 and 4 are the processes of FIGS. 2 and 207, respectively. This is the process executed in 208.
The "stable state load" is, as in the present embodiment, in the device (microcomputer 11) for measuring the current, the output on signal or the output off signal is simply input, and the information of the output on / off period is input. For loads in which the output signal is kept on or off for a period of time when there is no information, that is, when the device (microcomputer 11) that measures the current does not have information on when the output is turned on or off. This is treated as a stable state of the output signal. This "fixed period" is set to 20 ms in this embodiment. 20 ms is based on the cycle of the AC power supply 5 (cycle of the power supply of 50 Hz). In the case of switching based on the zero cross of the power supply based on the time proportional control, the signal state is determined by waiting at least half a cycle, but the signal state is set to one cycle with a margin. That is, it absorbs the delay due to the fact that zero cross is the operating reference.
In the present embodiment, as an example, it is determined whether or not the output on signal is in a stable state and whether or not the output off signal is in a stable state.

First, in step 201 (FIG. 2), 1 is substituted for n as the initialization process. As described above, in the present embodiment, there are 16 channels in the portion surrounded by the dotted line in FIG. 1, and numbers 1 to 16 are assigned to each channel, and n is a variable indicating this channel number. Hereinafter, this channel number is referred to as CHn, the CT of channel 1 is referred to as CT1, and the CT of channel n is referred to as CTn. Further, the heater of the channel n is referred to as a heater n.
Although the description is omitted in FIG. 2, 0 is assigned to each flag of the CHn output flag and the CHn state flag as the initialization process.
The information indicated by each flag is as follows.
CHn output flag: Indicates whether the output signal for the heater n input from the microcomputer 31 of the temperature controller 3 is on or off.
-CHn status flag: Heater n is 1. Stable state load with output on signal, 2. The output off signal indicates whether the load is in a stable state, which is neither 3.1 nor 2.

The loop 1 following step 201 repeats the processes of steps 202 to 209 from 1 to 16 (that is, for all channels).

In step 202, the state of the CHn output flag is determined, and if this is "0", the process proceeds to step 203, if it is "ON", the process proceeds to step 207, and if it is "OFF", the process proceeds to step 208. do.

Since the CHn output flag = 0 in the initial state, in the first process, the process proceeds to step 203 and the CHn timer (timekeeping) is started.
In the following step 204, it is determined whether the output signal for the heater n received from the microcomputer 31 of the temperature controller 3 is on or off, and if it is on, the CHn output flag = ON (step 204). → Step 205), if it is off, the CHn output flag = OFF (step 204 → step 206). It should be noted that the expression "flag = ON" or the like is for ease of understanding, and may be numerical information such as "1" in the program. The same applies to each flag described below.
In the following step 209, n is incremented and the processing of loop 1 is repeated.

If the CHn output flag is “ON” as a result of the determination in step 202, the ON stable state determination process of step 207 is performed.
FIG. 3 is a flowchart showing the on-stable state determination process of step 207.
In step 301, it is determined whether the output signal for the heater n received from the microcomputer 31 of the temperature controller 3 is on or off, and if it is on, the process proceeds to step 302 and the output signal is off. If so, the process proceeds to step 304.

If the determination result in step 301 is on, this means that the output signal is kept on. In step 302, it is determined whether or not the maintenance time of this on state continues for a predetermined time (20 ms in this embodiment), and if it continues, the process proceeds to step 303 and the CHn state flag is set to “on stable”. (Stable state load with output on signal) ”, and the on stable state judgment process is terminated. On the other hand, if it has not continued for a predetermined time, step 303 is skipped and the on stable state determination process is terminated.

If the determination result in step 301 is off, this means that the output signal has changed from the on state to the off state. Therefore, assuming that the off state is newly started, the CHn timer (timekeeping) is restarted in step 304, and the CHn output flag = OFF is set in step 305. Further, the CHn state flag is set to 0 (step 306). As mentioned above, the CHn state flag is set by the heater n.
1. 1. Stable state load with output on signal 2. It is information indicating whether the output off signal is a stable state load 3.1 or 2, and immediately after the output signal changes from the on state to the off state, it corresponds to 3 and 0 indicating this is indicated. It is assigned to the CHn state flag.

By the on-stable state determination process of FIG. 3, the load (channel) in the stable state is determined by the output on signal, and the information is obtained as the CHn state flag.

If the CHn output flag is “OFF” as a result of the determination in step 202 of FIG. 2, the off stable state determination process of step 208 is performed.
FIG. 4 is a flowchart showing the off-stability state determination process in step 208.
Since the off-stable state determination process of FIG. 4 is a process in which the on and off of the on-stable state determination process of FIG. 3 are simply switched, the description thereof will be omitted here.
By the off-stable state determination process of FIG. 4, the load (channel) in the stable state is determined by the output off signal, and the information is obtained as the CHn state flag.

The process of determining whether or not the load is in a stable state in FIGS. 2 (and 3 and 4) is always repeatedly executed in a cycle sufficiently fast with respect to the power cycle of the AC power source 5, so that each CHn can be determined. The status of the output signal is constantly monitored, and the information on whether or not the load is in a stable status is constantly updated.

5 to 9 are flowcharts showing an example of the process of measuring the current flowing through each load (heater 6), and the processes of FIGS. 6 to 9 are the processes executed in steps 505 to 508 of FIG. 5, respectively. be.
Although the description is omitted in FIG. 5, as the initialization process, the A / D count value acquisition process by the internal reference value acquisition unit 23, the CHn on current value measurement flag, the CHn off current value measurement flag, and the like. A process of substituting 0 for each flag such as the internal reference value import flag and the internal reference value flag is performed.
The information indicated by each flag is as follows.
-CHn on-current value measurement flag: A flag for each channel indicating whether or not the current in the on state of the output signal has been measured. The numerical value corresponding to the number of measurements is stored.
-CHn off current value measurement flag: A flag for each channel indicating whether or not the current in the off state of the output signal has been measured. The numerical value corresponding to the number of measurements is stored.
-Internal reference value import flag: A flag indicating whether or not the internal reference value (A / D count value) has been imported. A numerical value corresponding to the number of times that the A / D count values of both the LOW level and the HIGH level are acquired is stored.
-Internal reference value flag: A switching variable for alternately taking in the LOW level A / D count value and the HIGH level A / D count value.

First, in step 501 (FIG. 5), the CHn state flag set by the process of FIGS. 2 (and 3 and 4) described above is “on stable”, and the CHn on current value measurement flag is 0. Determine if there is. The CHn heater corresponds to "on measurable unmeasured load". When there is an “on-measurable unmeasured load”, the current measurement process of the corresponding channel is performed by the on-output current measurement process described later (step 501: Yes → step 505). That is, the current measurement of the “on-measurable unmeasured load” is given priority. The result measured when the output is turned on is the current measured value of the load 6, and the current measured value of the load 6 is a measured value used in various control processes other than the determination of the disconnection alarm, and this is given priority. It is something to capture.
If there is no “on measurable unmeasured load”, the process proceeds to step 502, and it is determined whether or not there is a CHn whose CHn state flag is “off stable”. When there is a CHn of "off stability", it is determined whether or not there is a CHn whose CHn off current value measurement flag is 0 (step 502: Yes → step 503). The CHn heater corresponds to "off measurable unmeasured load". When there is an “off-measurable unmeasured load”, the current measurement process of the corresponding channel is performed by the off-output current measurement process described later (step 503: Yes → step 506).
As a result of the determination in step 502, if there is no “off-stable” CHn, the process proceeds to step 504 and it is determined whether or not there is an “on-stable” CHn. When there is no “on-stable” CHn in the determination result of step 504, there is no stable channel (that is, no current-measurable channel) for both on and off. In this case, the process proceeds to step 508, and the internal reference value acquisition process described later is performed. When there is no channel on which the current can be measured, the A / D count value is taken in.
If the determination in step 503 is No, or if the determination in step 504 is Yes, the process proceeds to step 507, and the remeasurement process described later is performed. When there is a measurable (stable state) channel but there is no unmeasured channel, the measured channel is remeasured.

FIG. 6 is a flowchart showing the on-output current measurement process of step 505.
As described above, this process is a current measurement process for “on-measurable unmeasured load”.
In step 601 is determined which channel has the smallest n among CHn (that is, “on-measurable unmeasured load”) in which the CHn state flag is “on stable” and the CHn on-current value measurement flag is 0.
In the following step 602, the current measurement is started for the “on-measurable unmeasured load” of the channel selected in step 601 and the measurement of the measurement time is started. That is, the smaller the channel number, the more preferentially the current measurement is performed. Therefore, the channel number is also the information that determines the priority of the current measurement.
The current measurement is performed by instructing the MUX 12 from the microcomputer 11 to select the CT 22 of the corresponding channel, whereby the signal from the CT 22 of the corresponding channel is input to the microcomputer 11. ..

In step 603, it is determined whether or not the CHn state flag of the channel whose current is being measured is maintained as “on stable”. As described above, the CHn state flag of each channel is constantly updated by the process of FIG. 2 (and FIGS. 3 and 4), and it is determined whether or not the stable state is maintained by this.
When the CHn state flag is no longer “on stable”, the on output current measurement process is terminated (step 603: No → end). In this case, the current measurement of the corresponding channel is not completed, and the current is treated as unmeasured.
On the other hand, when the CHn state flag is "on stable" and maintained for a predetermined time (50 ms in this embodiment), the current measurement is completed and the measured value is stored as the current value at the time of the output on signal of the corresponding channel. Then, the CHn on-current value measurement flag is incremented (step 604: Yes → step 605).
When the measured value is taken in, the signal from the CT 22 is calibrated based on the A / D count value taken in by the internal reference value taking unit 23.

By the above on-output current measurement process, the current measurement of the “on-measurable unmeasured load” is performed in the order of priority according to the channel number.

FIG. 7 is a flowchart showing the off-output current measurement process of step 506 of FIG.
The off-output current measurement process (Fig. 7) is just the on / off switch of the on-output current measurement process (Fig. 6), and the basic processing concept is the same, so the explanation here is omitted. do.

FIG. 9 is a flowchart showing the internal reference value acquisition process of step 508 of FIG.
Step 508 of FIG. 5 is a process executed when there is no channel in a stable state, that is, there is no channel whose current can be measured, and is a process of fetching the A / D count value by the internal reference value fetching unit 23. be.

In step 901 (FIG. 9), the value of the internal reference value flag is determined, and if it is 0, the process proceeds to step 902, and if it is 1, the process proceeds to step 904.
If the internal reference value flag is 0, the Low level A / D count value is fetched (step 902), and the internal reference value flag is changed to 1.
If the internal reference value flag is 1, the high level A / D count value is fetched (step 904), and the internal reference value flag is changed to 0. Further, since the A / D count values of both the Low level and the High level are captured by the above processing, the internal reference value capture flag is incremented (step 906).
In this way, each time the internal reference value acquisition process is executed, the A / D count values of the Low level and the High level are acquired in order, and the A / D count values of both the Low level and the High level are fetched. At that time, the internal reference value acquisition flag is incremented.

FIG. 8 is a flowchart showing the remeasurement process of step 507 of FIG.
Step 507 of FIG. 5 is a process executed when there is a measurable (stable state) channel but there is no channel whose current has not been measured, and is a process of re-measuring the measured channel or taking an internal reference value. It is intended to perform embedded processing.
The channel to be remeasured here corresponds to "measurable measured load".

In step 801 (FIG. 8), the channel in which the CHn state flag is “on stable” or “off stable” and the CHn on current value measurement flag or the CHn off current value measurement flag is the smallest is determined. That is, among the measurable (stable state) channels, the channel with the smallest number of measurements is discriminated.
In the following step 802, the minimum CHn on current value measurement flag or CHn off current value measurement flag determined in step 801 is compared with the internal reference value acquisition flag. If the internal reference value acquisition flag is smaller, the process proceeds to step 809 to perform the internal reference value acquisition process, and if the CHn on current value measurement flag or the CHn off current value measurement flag is small, step 803 or later is performed. Move to the processing of. The number of times the current is measured is compared with the number of times the internal reference value is taken in, and the smaller number of times is measured or taken in. Since the internal reference value acquisition process in step 809 is the process shown in FIG. 9, the description thereof is omitted here.

In step 803, when there are a plurality of channels determined in step 801 are selected with priority given to "on-stable", and the channel number is the smallest among them.
Subsequent processes of steps 804 to 808 are current measurement processes for the channels determined in step 803, and are the same processes as steps 602 to 605 of FIG. 6 or steps 702 to 705 of FIG. 7 except for step 806. ..
In step 806, the CHn state flag is “on stable” and the CHn on current value measurement flag is 0 (that is, “on measurable unmeasured load”) or the CHn state flag during the current measurement of the channel. Is "off stable" and the CHn off current value measurement flag is 0. It is determined whether or not CHn (that is, "off measurable unmeasured load") has occurred. As described above, the CHn state flag of each channel is constantly updated by the process of FIG. 2 (and FIGS. 3 and 4), and it is determined whether or not an unmeasured channel is generated in a stable state. be.
If an unmeasured channel is generated in the stable state, the current measurement process is stopped and the remeasurement process of the measured channel is terminated. As a result, the current measurement of the unmeasured channel in the stable state is started immediately.

The explanation will be continued by returning to FIG.

By the processes of steps 501 to 504 and steps 505 to 508 (FIGS. 6 to 9) described above, a channel is selected according to a predetermined priority, and current measurement (or internal reference value acquisition) of the channel is performed.
In step 509 following this, it is determined whether or not the CHn on current value measurement flag and the CHn off current value measurement flag of all channels are not 0 and the internal reference value acquisition flag is not 0. That is, it is determined whether or not all the current measurements and the internal reference values have been taken in, and if all the current measurements and the internal reference values have been taken in, the process proceeds to step 511. ..
In step 511, the CHn on current value measurement flag, the CHn off current value measurement flag, and the internal reference value acquisition flag of all channels are reset (0 is substituted), and the process returns to step 501 to repeat the above process.

Step 510 is a timeout process, and if all measurements and acquisitions are not completed even after a predetermined period has elapsed, the CHn on current value measurement flag, the CHn off current value measurement flag, and the internal reference value acquisition of all channels are taken. The inclusion flag is reset (0 is substituted) (step 510: Yes → step 511), the process returns to step 501, and the above process is repeated.
The "predetermined period" in the time-out process is appropriately determined based on the design concept. For example, the on / off state of the output is monitored, and the output cycle is determined from the number of on / off switching times (by switching twice). 2 cycles), and the case where 24 cycles have passed is regarded as the lapse of the "predetermined period".

Next, with respect to the processing operation described above, the operation of the current measurement of the present embodiment will be described with reference to FIGS. 10 to 12, which are timing diagrams that briefly exemplify a part thereof. In FIGS. 10 to 12, for the sake of simplicity, only the current measurement for the output on signal is targeted.

FIG. 10 focuses on CH4 and simplifies the other channels by assuming that all channels are measured in current in order.
Since the output signal for CH4 is not on when the order of CH4 is in the order of channel numbers, the current measurement of CH4 at this point is skipped and the current measurement of CH5 is performed.
After that, the output signal for CH4 is turned on during the current measurement of CH7, and this state is maintained, and CH4 is in a stable state during the current measurement of CH8. CH8 waits for the completion of the current measurement of CH8 because this is the first current measurement (not the remeasurement).
After the current measurement of CH8 is completed, CH4 having the smallest channel number among the unmeasured ones becomes the current measurement target.

FIG. 11 focuses on CH4 as in FIG. 10, and is simplified by assuming that all channels are measured in order for the other channels, but all channels other than CH4 have been measured for current. The case is shown.
Until CH4 becomes stable, each channel that has already been measured is remeasured in the order of channel number.
If CH4 becomes stable during the remeasurement of CH8, the remeasurement of CH8 is stopped and the current measurement of CH4 is started immediately. When the current measurement of CH4 is completed, the measurement of all channels is completed, so that all channels are returned to unmeasured, and then the measurement process of each channel is repeated.

FIG. 12 focuses on CH4 as in FIG. 10, and simplifies the other channels by assuming that all channels are measured in current in order.
Since CH4 was in a stable state when the order of CH4 was changed in the order of channel numbers, the current measurement of CH4 was started, but the output signal was turned off in the middle of the current measurement, so that the current measurement of CH4 was performed. It is stopped (the current measurement of CH4 is not completed), and the measurement of CH5 is started immediately. After that, when CH4 becomes stable again, CH10 is in the process of performing the first current measurement, and waits for the completion of the current measurement of CH10.
After the current measurement of CH10 is completed, CH4 having the smallest channel number among the unmeasured ones becomes the current measurement target.

As described above, according to the present embodiment, the current value at the time of the output on signal of each channel and the current value at the time of the output off signal of each channel are efficiently measured.
The current value at the time of the output on signal and the current value at the time of the output off signal of each channel acquired and stored based on the above processing by the microcomputer 11 are transmitted to the microcomputer 31 of the temperature controller 3. Utilizing this, the microcomputer 31 performs disconnection alarm processing and short circuit (welding) alarm processing. That is, when the current value at the time of the output on signal does not reach a predetermined value, it is determined that the wire is disconnected in the corresponding channel, and a disconnection alarm is issued (for example, alarm information is transmitted to the host device via the communication device 4). ). If the current value at the time of the output off signal is equal to or higher than a predetermined value, it is determined that welding is performed in the corresponding channel, and a welding alarm is issued (for example, alarm information is transmitted to a higher-level device via the communication device 4). ..

As described above, according to the present embodiment, when there is no information on the on / off period of the output signal in the microcomputer 11, that is, when the device (microcomputer 11) for measuring the current has the output turned on or off from what time to what time. Even if there is no information as to whether or not it will continue, the current measurement of each channel can be performed efficiently.
In the present embodiment, as shown in FIG. 1, as a rough configuration, an output controller 1 that controls the SSR 21 and the like, an output controller 2 equipped with the SSR 21 and the CT 22 described above, and feedback control such as a PID are used. It is provided with a temperature controller 3 that calculates a control signal that controls on / off of the SSR 21. When the microcomputer 11 in such a configuration is provided with a current measurement function, it cannot be supported by the conventional method, or additional configuration and processing are required to support it, which reduces the degree of freedom in device design. .. On the other hand, according to the present embodiment, such restrictions are reduced.
It should be noted that the application of the present invention is not limited to the configuration as shown in FIG. 1, and for example, all or a part of the output controller 1, the output controller 2, and the temperature controller 3 are integrated in an arbitrary combination. It is possible to take appropriate measures such as those that are present or those that are further subdivided.
Further, in the present embodiment, the processing control entity is the microcomputer 11, and each function is described as being implemented by software. However, a part or all of the processing described above is realized by hardware. It doesn't matter if there is one. Further, the control subject when each function is implemented by software is not limited to the microcomputer, and various devices capable of executing the above-described functions can be used.

In this embodiment, an example is obtained in which both the current value at the time of the output on signal and the current value at the time of the output off signal are acquired, and the current measurement at the time of the output on signal is prioritized. It may be the one that does not set the priority. Further, only one of the current value at the time of the output on signal and the current value at the time of the output off signal may be acquired.

In the present embodiment, a process of giving priority to each channel according to its number is taken as an example, but a process of not giving a special priority to each channel (a process of randomly processing) may be used. .. However, when there are high and low in the importance among a plurality of loads, it is preferable to give priority information corresponding to the high and low.
In the present embodiment, the heater is taken as an example as a load, but the present invention is not limited to this, and the present invention can be applied as a current measurement of various loads other than the heater.

1. 1. .. .. Output controller (current measuring device)
11. .. .. Microcomputer (stable state judgment unit, current measurement unit)
12. .. .. MUX (current measurement signal selection output unit)
2. 2. .. .. Output device 21. .. .. SSR
22. .. .. CT (current measuring instrument)
23. .. .. Internal reference value capture unit 3. .. .. Temperature controller (disconnection detection device)
6. .. .. Heater (load)

Claims (10)

A current measurement signal selection output unit that switches and outputs a current measurement signal from a current measuring device provided in each of the power supply paths for each of a plurality of loads.
A load in which an output on signal or an output off signal of power supply for each of the plurality of loads is received and the period of receiving the output on signal or the output off signal continues for a predetermined time or longer is defined as a stable state load. Stable state judgment unit and
A current measurement signal corresponding to a measurable unmeasured load which is a load determined to be a stable state load and whose current value has not been measured is received from the current measurement signal selection output unit to measure the current, and the current is measured. Equipped with a current measuring unit that makes the measured load already measured ,
Priority information is associated with the load, and when there are a plurality of measurable unmeasured loads, the current of the load having the highest priority based on the priority information is measured. measuring device. A current measurement signal selection output unit that switches and outputs a current measurement signal from a current measuring device provided in each of the power supply paths for each of a plurality of loads.
A load in which an output on signal or an output off signal of power supply for each of the plurality of loads is received and the period of receiving the output on signal or the output off signal continues for a predetermined time or longer is defined as a stable state load. Stable state judgment unit and
A current measurement signal corresponding to a measurable unmeasured load which is a load determined to be a stable state load and whose current value has not been measured is received from the current measurement signal selection output unit to measure the current, and the current is measured. Equipped with a current measuring unit that makes the measured load already measured,
An on-measurable unmeasured load in which the output on signal is a stable state load that has continued for a predetermined time or longer and a current value has not been measured, and a stable state load in which the output off signal has continued for a predetermined time or longer and a current. A current measuring device characterized in that when an off-measurable unmeasured load whose value is unmeasured is simultaneously present, the current measurement of the on-measurable unmeasured load is given priority. A current measurement signal selection output unit that switches and outputs a current measurement signal from a current measuring device provided in each of the power supply paths for each of a plurality of loads.
A load in which an output on signal or an output off signal of power supply for each of the plurality of loads is received and the period of receiving the output on signal or the output off signal continues for a predetermined time or longer is defined as a stable state load. Stable state judgment unit and
A current measurement signal corresponding to a measurable unmeasured load which is a load determined to be a stable state load and whose current value has not been measured is received from the current measurement signal selection output unit to measure the current, and the current is measured. Equipped with a current measuring unit that makes the measured load already measured,
If there is no measurable unmeasured load and there is a measurable measured load that is determined to be the stable state load and the current value has been measured, the current measurement of the measurable measured load is performed. A current measuring device characterized by that. If the measurable unmeasured load occurs during the current measurement of the measurable measured load, the current measurement of the measurable measured load shall be stopped and the current measurement of the measurable unmeasured load shall be performed. The current measuring device according to claim 3 . The current measuring device according to any one of claims 1 to 4 , wherein when all the current values of the plurality of loads have been measured, all the loads have not been measured. The current measuring device according to any one of claims 1 to 5 , wherein all loads are not measured after a lapse of a predetermined period. A current measurement signal selection output unit that switches and outputs a current measurement signal from a current measuring device provided in each of the power supply paths for each of a plurality of loads.
A load in which an output on signal or an output off signal of power supply for each of the plurality of loads is received and the period of receiving the output on signal or the output off signal continues for a predetermined time or longer is defined as a stable state load. Stable state judgment unit and
A current measurement signal corresponding to a measurable unmeasured load which is a load determined to be a stable state load and whose current value has not been measured is received from the current measurement signal selection output unit to measure the current, and the current is measured. Equipped with a current measuring unit that makes the measured load already measured,
It is equipped with an internal reference value capture unit that captures the A / D count value at the LOW level or HIGH level of the signal circuit.
A current measuring device, characterized in that, when there is no load determined to be a stable state load, an acquisition process is performed by the internal reference value acquisition unit. When the capture process is performed by the internal reference value capture unit, it is assumed that the internal reference value has been captured, and the current values of all the loads have been measured and the internal reference value has been captured. The current measuring device according to claim 7 , wherein all the loads are unmeasured and the internal reference value is not taken in. A disconnection detection device including the current measuring device according to any one of claims 1 to 8 . The output on signal or output off signal of the power supply for each of the plurality of loads to which the priority information is associated is received, and the period of receiving the output on signal or the output off signal continues for a predetermined time or longer. Steps to make the load a stable load, and
A step of measuring the current of a measurable unmeasured load which is a load determined to be a stable state load and whose current value has not been measured, and making the measured load already measured.
A current measuring method comprising:, when there are a plurality of measurable unmeasured loads, a step of measuring the current of the load having the highest priority based on the priority information .

Images