JP3918592B2 - Overcurrent protection device, overcurrent protection method and program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for protecting a load from overcurrent.
[0002]
[Prior art]
An overcurrent protection device in an air conditioner is installed, for example, for overload protection of a compressor. As this overcurrent protection device, conventionally, when the drive current of the load becomes overcurrent, the drive current is cut off by the bimetal connected to the current path based on the temperature rise of the load or the like at that time. (First prior art).
[0003]
Further, for example, there is a device that detects a drive current of a load using a current sensor, detects whether or not it is an overcurrent, and cuts off the drive current in the case of an overcurrent (second prior art). . In the second prior art, the CPU determines whether or not there is an overcurrent by defining a reference current value for determining an overcurrent in a preset software program, and performs a drive current cutoff control. I was doing.
[0004]
[Problems to be solved by the invention]
In the first prior art described above, since the temperature characteristic of a component called bimetal is used, it is difficult to make adjustments such as changing the reference current value for determining the overcurrent of the overcurrent protection device.
[0005]
In the second prior art, although it is easy to change the setting of the reference current value with a software program, the reference current value is the same during the start period and during normal operation. For this reason, for example, the temperature of the winding in the compressor is likely to rise more rapidly than during normal operation during the start-up period of the compressor, and a large current may flow more easily during normal operation than during normal operation. Not considered. Therefore, the mode of overcurrent protection did not change according to the change in the situation at that time.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a technique for protecting from overcurrent that can perform finer overcurrent protection processing.
[0007]
[Means for Solving the Problems]
  In order to solve the above problem, the invention according to claim 1 measures the drive current (I) of the load (MC), and changes the reference current value depending on whether the load is started or during normal operation, The measured drive current is compared with the reference current value, and the presence or absence of an overcurrent state is determined based on the comparison result.The overcurrent operation confirmation time for confirming whether or not the overcurrent state exists is shorter during the load starting period than during normal operation.Is.
[0008]
A second aspect of the present invention is the overcurrent protection device according to the first aspect, wherein the drive current (I) is cut off when it is determined that the overcurrent state is present.
[0009]
The invention according to claim 3 is the overcurrent protection device according to claim 1 or 2, wherein the current sensor (2) for measuring the drive current (I) of the load (MC), and the load The reference current value is changed depending on whether it is during the start-up period or during normal operation, the drive current measured by the current sensor is compared with the reference current value, and the presence or absence of an overcurrent state is determined based on the comparison result And a control unit (4) for cutting off the drive current when it is determined that the current state is an overcurrent state.
[0012]
  Claim4The invention as described in claim 1 to claim 13The overcurrent protection device according to any one of the above, wherein a current increase rate of the drive current (I) immediately after the load (MC) is started is obtained, and the current increase rate is a normal current stored in advance. A comparison is made as to whether or not the rate of increase is greater, and the presence or absence of an overcurrent state is determined based on the comparison result.
[0013]
  Claim5According to the invention described in the above, the current decrease rate of the drive current (I) immediately after the peak current of the load (MC) is obtained, and whether or not the current decrease rate is smaller than a normal current decrease rate stored in advance. The comparison is made, and the presence or absence of an overcurrent state is determined based on the comparison result.
[0014]
  Claim6The invention as described in claim 1 to claim 14The overcurrent protection device according to any one of the above, wherein a current decrease rate of the drive current (I) immediately after the peak current of the load (MC) is obtained, and the current decrease rate is a normal value stored in advance. Whether or not the current drop rate is smaller is compared, and the presence or absence of an overcurrent state is determined based on the comparison result.
[0015]
  Claim7The invention as described in claim 1 to claim 16The overcurrent protection device according to any of the above, wherein the drive current (I) is cut off when it is in an overcurrent stateUntil the supply restarts after the drive current is cut off.The cutoff period of time cuts off the drive current for other purposesSaidIt is set differently from the cutoff period.
[0016]
  Claim8The invention as described in claim 1 to claim 17Wherein the load (MC) is a compressor of an air conditioner, and the opening degree of the motor-operated valve for switching the refrigerant supply of the compressor is the driving current ( I)TheShut offdidlaterRestart the supply of the drive current (I)The case where the load is restarted is different from the case where the load is not restarted.
[0017]
  Claim9The invention described in claim 18The overcurrent protection device according to claim 1, wherein the driving current (I)TheShut offdidlaterRestart the supply of the drive current (I)The opening degree of the motor-operated valve for switching the refrigerant supply of the compressor when the load is restarted is larger than in cases other than the restart.
[0018]
  Claim10According to the invention, the drive current (I) of the load (MC) is measured, the reference current value is changed depending on whether the load is started or during normal operation, and the drive current is compared with the reference current value. And determine the presence or absence of an overcurrent state based on the comparison result,The overcurrent operation confirmation time for determining whether or not the overcurrent state exists is shorter during the load starting period than during normal operation..
[0019]
  Claim11The invention described in claim 110In the overcurrent protection method described in (1), the drive current (I) is cut off when it is determined that the overcurrent state is present.
[0020]
  Claim12The invention described in claim 110Or claims11The overcurrent protection method according to claim 1, wherein a first step of measuring a drive current (I) of the load (MC) with a current sensor (2) is performed separately between a start period of the load and a normal operation. A second step of changing and setting a reference current value and a comparison of the drive current measured by the current sensor with respect to the reference current value, and determining the presence or absence of an overcurrent state based on the comparison result And a fourth step of cutting off the drive current when it is determined in the third step that the current state is an overcurrent state.
[0023]
  Claim13The invention described in claim 110Or claims12The overcurrent protection method according to any one of the above, wherein a current increase rate of the drive current (I) immediately after starting the load (MC) is obtained, and the current increase rate is a normal current stored in advance. A comparison is made as to whether or not the rate of increase is greater, and the presence or absence of an overcurrent state is determined based on the comparison result.
[0024]
  Claim14According to the invention described in the above, the current decrease rate of the drive current (I) immediately after the peak current of the load (MC) is obtained, and whether or not the current decrease rate is smaller than a normal current decrease rate stored in advance. The comparison is made, and the presence or absence of an overcurrent state is determined based on the comparison result.
[0025]
  Claim15The invention described in claim 110Or claims13The current drop rate of the drive current (I) immediately after the peak current of the load (MC) is obtained, and the current drop rate is a normal value stored in advance. It is compared whether or not it is smaller than the current drop rate, and the presence or absence of an overcurrent state is determined based on the comparison result.
[0026]
  Claim16The invention described in claim 110Or claims15The overcurrent protection method according to any one ofSaidThe drive current (I) is cut off when it is in an overcurrent state.After that, the supply of the drive current (I) is restarted and the load is restarted.If the interruption period is to cut off the drive current for other purposesSaidIt is set differently from the cutoff period.
[0027]
  Claim17The invention described in claim 110Or claims16Wherein the load (MC) is a compressor of an air conditioner, and the opening degree of the motor-operated valve for switching the refrigerant supply of the compressor is the driving current ( I)TheShut offdidlaterRestart the supply of the drive current (I)The case where the load is restarted is different from the case other than the restart.
[0028]
  Claim18The invention described in claim 117The overcurrent protection method according to claim 1, wherein the driving current (I)TheShut offdidlaterRestart the supply of the drive current (I)The opening degree of the motor-operated valve for switching the refrigerant supply of the compressor when the load is restarted is larger than in cases other than the restart.
[0029]
  Claim19The invention described in claim 1 is executed by a computer,10Or claims17A program for realizing the overcurrent protection method according to any one of the above.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
<Overview>
FIG. 1 is a diagram showing an overcurrent protection device according to an embodiment of the present invention. This overcurrent protection device protects the compressor MC from overcurrent when the compressor MC of the air conditioner (air conditioner) is driven as a load. As shown in FIG. 1, in order to detect the drive current I in the current path 1 for supplying one phase of the current supplied to the compressor MC via the current path 1 (hereinafter simply referred to as “drive current I”). The current sensor 2 is installed. Then, the control unit 4 determines whether or not the drive current I is overcurrent. When the control unit 4 determines that the drive current I is overcurrent, the drive current I is cut off through the current cut-off unit 3. At this time, the overcurrent operation determination time spent to cut off the drive current I and the reference current value as a threshold value for whether or not overcurrent are different between the starting period of the compressor MC and the normal operation. Yes. In this overcurrent protection device, the “starting period” means that the driving current I suddenly increases from the starting point of the compressor MC, the peak current passes, and the driving current I attenuates to a constant normal state. This is the period during which the time required up to this time is measured in advance and initially stored in the ROM or the like. “During normal operation” refers to after the time initially stored in the ROM has elapsed as described above after the compressor MC is started.
[0031]
Further, not only the current level of the driving current I in the starting period but also the overcurrent state is detected by the change of the driving current I. Furthermore, the setting of the cut-off time of the drive current I is performed independently without being limited by the load stop time set for the purpose other than overcurrent protection. At the same time, this overcurrent protection device performs motor-operated valve control when the compressor MC is restarted.
[0032]
Here, the control unit 4 uses a microcomputer including a CPU, ROM (also used for setting a start-up period as described above), RAM, and a timer, and is executed by the CPU based on a predetermined software program. It is a functional element that operates. As the ROM, a write memory such as an EEPROM is used at any time, whereby the software program defining the overcurrent protection process can be changed.
[0033]
The current interrupting unit 3 includes a magnet switch 3a disposed in the current path 1 for supplying the driving current I to the compressor MC, and a relay 3b for switching and controlling the magnet switch 3a based on a command from the control unit 4. Prepare. Here, FIG. 1 shows an example in which the compressor MC is three-phase driven. For this reason, the magnet switch 3a is composed of three-phase switch units 3ar, 3as, and 3at.
[0034]
Next, setting of various functions in the software program in the control unit 4 will be described.
[0035]
<Setting of reference current value>
For example, during the start-up period of the compressor MC, which is a load, the temperature of the winding in the compressor MC is likely to increase more rapidly than during normal operation, so it is necessary to suppress such temperature increase. Considering this, it is desirable to set the reference current value as low as possible. On the other hand, for example, in a compressor (load) MC driven by a three-phase (R, S, T: see FIG. 1) induction motor, a relatively large current flows from the power source during the start period. In consideration of preventing erroneous detection, it is desirable to set a large value corresponding to a large current as the reference current value. In consideration of these points, the reference current value during the starting period is obtained by experiment as a value different from the reference current value during normal operation, and is then stored in advance in a write memory such as an EEPROM. Keep it. In this case, for example, the reference current value in the starting period is set larger than the reference current value during normal operation.
[0036]
Then, for each of the starting period of the compressor MC and during normal operation, each reference current value and the measured current value obtained by the current sensor 2 are compared as needed, and whether or not the measured current value is overcurrent. Judging. In this way, since the reference current value is stored in the writing memory as needed, it is easy to change the setting of the reference current value.
[0037]
Here, with respect to this reference current value, in particular, when the reference current value in the starting period of the compressor MC is inserted, the “starting reference current value” is set. When the reference current value during the normal operation of the compressor MC is set, ".
[0038]
Specific examples of the starting reference current value and the normal operation reference current value are shown in FIG. In FIG. 2, the change in the current value is conceptually illustrated as a curve regardless of the starting reference current value and the normal operation reference current value. In the case of the starting period of the compressor MC, in FIG. 2, when the driving current I detected by the current sensor 2 exceeds the starting reference current value I1 for a predetermined overcurrent operation confirmation time T01 or more, the control unit 4 Determines that such a situation is an overcurrent state, and gives an instruction to the current interrupting unit 3 to interrupt the drive current I of the compressor MC. In the case of normal operation of the compressor MC, in FIG. 2, when the drive current I detected by the current sensor 2 exceeds the normal operation reference current value I2 for a predetermined overcurrent operation confirmation time T02 or more. The control unit 4 determines that such a situation is an overcurrent state, gives an instruction to the current interrupting unit 3, and interrupts the drive current I of the compressor MC (timing t1 in FIG. 2). Here, the starting reference current value I1 and the normal operation reference current value I2 are obtained by experiments as different values independent from each other as described above, and then stored in advance in a write memory such as an EEPROM. Keep it.
[0039]
<Setting of overcurrent operation confirmation time>
During the start-up period of the compressor MC, which is a load, the temperature of the windings in the compressor MC is likely to increase as compared with that during normal operation. Therefore, it is necessary to suppress this temperature increase. For this reason, it is desirable to set the overcurrent operation confirmation time spent to cut off the drive current I as short as possible. Therefore, as shown in FIG. 2, the overcurrent operation confirmation time T01 in the start-up period is set to a different and independent value from the overcurrent operation confirmation time T02 during normal operation based on the results of experiments and the like. As described above, in the overload protection process of this overcurrent protection device, the process from overcurrent detection to the cutoff of the drive current I can all be defined by a software program, so the overcurrent operation confirmation time can be easily changed. Is possible.
[0040]
<Setting of drive current cutoff time>
The cut-off time of the drive current I is necessary for sufficiently reducing the temperature of the winding in the compressor MC, and the compressor from the cut-off of the drive current I of the compressor MC to the restart of supply (retry). The waiting time of MC.
[0041]
Here, in the conventional overcurrent protection device, after the drive current I is cut off, the operator manually turns on the switch next, or sets the cutoff time for other purposes (for example, a pressure switch for high pressure protection). The compressor MC is restarted by setting the same load stop time (for example, 3 minutes) set in (for example, stopping the compressor MC).
[0042]
On the other hand, in this overcurrent protection device, by grasping control of the drive current I of the compressor MC by the judgment control in the control unit 4, grasping of the time point when the drive current I of the compressor MC is interrupted is grasped. Therefore, the setting of the cut-off time of the drive current I is uniquely defined on the software program regardless of the cut-off time of the drive current I set for other purposes, and the control unit 4 The shut-off time is controlled by controlling. This makes it possible to perform optimum drive current I cutoff control, for example, setting the optimum time as the drive current I cutoff time as the time required to sufficiently lower the temperature of the winding in the compressor. It becomes. Specifically, the interruption time when the drive current I is interrupted by the overcurrent protection device is the load stop set for other purposes (for example, the compressor MC is stopped by a pressure switch for high pressure protection). It is set longer than the time (for example, 3 minutes).
[0043]
In this case, for example, whether the compressor MC is stopped for overcurrent protection, or the compressor MC is stopped by the pressure switch described above, or the compressor MC is stopped due to an auto sensor abnormality. Each cause of stoppage of the machine MC is stored as a data flag in the RAM in the control unit 4, and the control unit 4 determines the cause of stoppage of the compressor MC by the data flag at the time of restart and responds to the cause of the stoppage. The compressor MC is restarted after waiting for the shut-off time.
[0044]
<Electric valve control setting when resuming supply of load drive current>
When the supply of the drive current I is resumed as described above after the drive current I is cut off, the opening of the motor-operated valve for the refrigerant is set larger than that during normal operation so that the refrigerant can easily flow. Thereby, restart of compressor MC can be performed efficiently.
[0045]
<Setting of gradient monitoring immediately after starting the measured current value>
In consideration of the overcurrent state in the locked state of the compressor MC, the controller 4 is set to monitor the gradient of the measured current value. That is, during the start-up period of the compressor MC, the gradient of the measured current value (current increase rate) is monitored, and when this exceeds a certain gradient, it is determined that the control unit 4 is overcurrent.
[0046]
FIG. 3 is a diagram showing a change in the driving current I during the start-up period of the compressor MC. A curve 11 is normal when the compressor MC is locked and the compressor MC stops due to overcurrent. Each shows the case of starting.
[0047]
Generally, when the compressor is locked, the drive current I tends to increase rapidly. In view of this, during the start-up period of the compressor MC, the current increase rate (that is, the current change amount per unit time) A from the start start time t2 to the time t3 of the peak current Pm for the drive current I (curve 11). Then, it is determined whether or not the current increase rate A1 is larger than that in the case of normal start (curve 12) stored in advance in the ROM, and it is determined whether or not the control unit 4 is in an overcurrent state.
[0048]
<Setting for monitoring current change from surge current after load start>
If the compressor MC is 12 in the normal start (FIG. 3), the peak current (surge current) Pm2 of the drive current I flows immediately after the start, and the drive current I rapidly decreases immediately after the time t3a. To do. On the other hand, when the compressor MC is in the locked state 11, the current I tends to be maintained at a high value as shown in FIG.
[0049]
In consideration of this, the absolute value of the current drop rate B (that is, the current change amount per unit time) B from the time point t3 of the peak current (surge current) Pm2 of the drive current I to the predetermined time T03 is stored in the ROM in advance. When the control unit 4 determines that the current drop rate B1 is smaller than the absolute value of the current decrease rate 12 in the case of normal starting, it is determined that the overcurrent state is caused by the locked state of the compressor MC.
[0050]
As a result, although the compressor (load) MC is in the locked state during the starting period, the current increase rate (i.e., the driving current I (reference numeral 11) from the starting start time t2 to the peak current (surge current) Pm time t3). Even when the current change amount per unit time) A does not increase so as to exceed the current increase rate A1 of 12 in the case of normal starting, the peak current (surge current) Pm2 flows at the time t3a. The overcurrent state can be detected with the small attenuation of the drive current I immediately after.
[0051]
<Operation>
A processing operation in the control unit 4 of the above-described overcurrent protection device will be described with reference to a flowchart.
[0052]
In step S01 in FIG. 4, the current drive 2 detects the drive current I of the compressor MC, and in step S02, the control unit 4 determines the presence or absence of an overcurrent state based on the drive current I and makes an abnormality determination. .
[0053]
Specific processing procedures for determining whether or not there is an overcurrent state are shown in FIGS.
[0054]
First, the drive current I is compared with a reference current value to determine whether or not there is an overcurrent state. FIG. 5 shows a process of comparing the drive current I with the reference current value and performing the second to determine whether or not an overcurrent state exists. First, in step S11, the control unit 4 determines whether or not the elapsed time from the starting time of the compressor MC is within a predetermined time stored in advance in a ROM or the like, whereby the compressor MC is started. It is determined whether it is during the period.
[0055]
If it is determined in step S11 that the compressor MC is in the starting period, the process proceeds to step S12. In step S12, the overcurrent operation confirmation time T01 of the starting period stored in advance in the ROM is substituted for the variable To and stored in the RAM. At the same time, the starting reference current value I1 stored in advance in the ROM is substituted for the variable Io and stored in the RAM. Then, it progresses to below-mentioned step S14.
[0056]
On the other hand, if it is determined in step S11 that the compressor MC is in normal operation, the process proceeds to step S13. In step S13, the overcurrent operation confirmation time T02 during normal operation stored in advance in the ROM is substituted for the variable To and stored in the RAM. At the same time, the normal operation reference current value I2 stored in advance in the ROM is substituted for the variable Io and stored in the RAM, and the process proceeds to step S14.
[0057]
In step S14, it is determined whether or not the drive current I is smaller than a variable Io stored in the RAM. If it is determined that the drive current I is smaller than the variable Io, the process shown in FIG. 5 is terminated and the process moves to the processes shown in FIGS.
[0058]
On the other hand, if it is determined that the drive current I is greater than or equal to the variable Io, the process proceeds to the next step S15. In step S15, based on the time measured by the timer built in the control unit 4, it is determined whether or not the elapsed time T from the start of the compressor MC is smaller than the variable To. If it is determined that the elapsed time T is smaller than the variable To, the process returns to step S14, and the determination of the magnitude of the drive current I is repeated.
[0059]
On the other hand, if it is determined in step S15 that the elapsed time T is greater than or equal to the variable To, it is determined in step S16 that the current is in an overcurrent state, and it is determined that an overcurrent (OC) operation described later should be executed.
[0060]
FIG. 6 is a flowchart showing a process procedure of gradient monitoring immediately after starting the measured current value. First, in step S21 in FIG. 6, the control unit 4 starts from the start start time t2 of the compressor MC shown in FIG. 3 to the time t3 of the peak current Pm based on the drive current I detected by the current sensor 2. The current increase rate A is acquired, and in step S22, it is determined whether or not the obtained current increase rate A is larger than the current increase rate A1 of 12 when the engine is normally started.
[0061]
If it is determined in this step S22 that the obtained current increase rate A is larger than the current increase rate A1 of 12 in the case of normal start, the process shown in FIG. Then, the process proceeds to the process shown in FIG.
[0062]
On the other hand, when it is determined in step S22 that the obtained current increase rate A is equal to or less than the current increase rate A1 of 12 when the engine is normally started, it is determined that the current is in an overcurrent state, and an overcurrent (OC ) Confirm that the operation should be performed.
[0063]
FIG. 7 is a flowchart showing a processing procedure for monitoring current change from the peak current after the load is started. First, in step S31 in FIG. 7, the current decrease rate B from the time point t3 of the peak current (surge current) Pm2 of the drive current I shown in FIG. Is acquired by the control unit 4 based on the above. In step S32, the control unit 4 determines whether or not the obtained current decrease rate B is smaller than the current decrease rate B1 of 12 when the engine is normally started.
[0064]
If it is determined in step S32 that the obtained current drop rate B is smaller than the current drop rate B1 of 12 when the engine is normally started, the process of FIG. 4 moves to step S03.
[0065]
On the other hand, if it is determined in step S32 that the obtained current drop rate B is equal to or greater than the current drop rate B1 of 12 when the engine is normally started, it is determined that the current is in an overcurrent state, and an overcurrent (OC ) Confirm that the operation should be performed.
[0066]
Here, returning to FIG. 4, in step S03, the operating state of the compressor MC is determined. FIG. 8 is a flowchart showing an outline of a processing procedure for determining and executing the operating state of the compressor MC.
[0067]
First, in step S40 in FIG. 8, it is determined whether or not the compressor MC should wait. If it should not wait here, the process of FIG. 8 ends. On the other hand, if it should be waited, in the next step S41, the overcurrent (OC) operation is performed in any of the above-described steps S16 (FIG. 5), S23 (FIG. 6) and S33 (FIG. 7). It is determined whether or not it is determined that it should be executed.
[0068]
If it is determined in step S41 that the overcurrent (OC) operation is to be executed, the process proceeds to step S42, and the drive current uniquely defined corresponding to the case of the overcurrent state on the software program. The interruption time T1 of I is set as a standby time, and the process proceeds to the next step S44.
[0069]
On the other hand, if it is determined in step S41 that it is not determined that the overcurrent (OC) operation should be performed, the process proceeds to step S43, and the drive current I defined corresponding to the normal state on the software program is determined. The interruption time T is set as a standby time, and the process proceeds to the next step S44.
[0070]
In the next step S45, the control unit 4 determines whether or not the interruption time (T1 or T) of the drive current I obtained in step S42 or S43 has elapsed based on the timing of the timer. If it is determined in step S45 that the cutoff time (T1 or T) of the drive current I has elapsed, in the next step S46, the control unit 4 performs compression at that time based on the data flag stored in the RAM. It is determined whether the start of the machine MC is a start after an overcurrent (OC) operation.
[0071]
If it is determined that the engine is started after the overcurrent operation, the process proceeds to step S47, where the electric valve opening P1 stored in the ROM in advance as data corresponding to the overcurrent operation is used as the current electric valve starting opening. And go to step S49.
[0072]
On the other hand, if it is determined in step S46 that the engine is not started after the overcurrent operation, the process proceeds to step S48, in which the motor-operated valve opening P stored in advance in the ROM as data corresponding to the overcurrent operation is used. The starting opening is set, and the process proceeds to step S49. In this case, P1> P.
[0073]
Steps S47 and S48 correspond to the control process for each actuator (motor valve) in step S04 in FIG.
[0074]
Then, moving to FIG. 4, in step S05, the control unit 4 gives an instruction to each actuator (electric valve) to open the electric valve with the motor valve starting opening obtained in steps S47 and S48 in FIG. Further, the compressor MC is started as in step S49 in FIG.
[0075]
As described above, in this overcurrent protection device, the reference current value and the overcurrent operation confirmation time that are different between the starting period of the compressor MC as a load and the normal operation based on the definition in the software program in the control unit 4. Therefore, the temperature of the winding in the compressor is likely to rise more rapidly than during normal operation during the start-up period of the compressor, and is larger during normal start-up than during normal operation. It is possible to appropriately change the mode of overcurrent protection according to the change in the situation at that time, for example, current can easily flow.
[0076]
In addition to comparing the drive current I with the reference current value, the current increase rate from the start to the peak current and the current decrease rate after the peak current are also monitored to determine whether there is an overcurrent state. Therefore, it is possible to easily and efficiently determine the overcurrent state caused by the locked state of the compressor MC.
[0077]
Furthermore, since the cut-off time of the drive current I due to overcurrent protection (the standby time of the compressor MC) and the standby time of the compressor MC due to other causes / purposes are set differently, the compressor optimal for overcurrent protection MC can be easily restarted.
[0078]
Furthermore, when restarting after overcurrent protection, the opening of the motor valve for supplying refrigerant is operated differently from the opening of the motorized valve during normal operation. It can be done efficiently.
[0079]
As described above, this overcurrent protection device can easily execute special control different from that during normal operation in overcurrent protection. Since the function setting for that purpose is only defined in the software program, special control for overcurrent protection can be easily executed at low cost.
[0080]
【The invention's effect】
  Claim 1, Claim 2, Claim 3, Claim10, Claims11And claims12According to the invention described in (1), the drive current of the load is measured by the current sensor, the reference current value is changed depending on whether the load is started or during normal operation, and the current sensor is measured with respect to the reference current value. And the presence or absence of an overcurrent state is determined based on the comparison result, so that the temperature of the winding in the compressor is likely to rise more rapidly than during normal operation during the start-up period of the load. In the start-up period, the mode of overcurrent protection can be appropriately changed according to the change in the situation, for example, a larger current flows more easily than during normal operation.In addition, since the overcurrent operation confirmation time for comparing the drive current and determining the presence / absence of the overcurrent state is changed depending on whether it is during the load start period or during normal operation, The mode of overcurrent protection can be appropriately changed according to the change in the situation, such as that the temperature of the winding of the coil tends to rise sharply compared to during normal operation.
[0082]
  ContractClaim4And claims13According to the invention described in the above, the drive current of the load is measured by the current sensor, the current increase rate immediately after the start of the load is obtained based on the measurement result, and the current increase rate is a normal value stored in advance. Since it is compared whether the current increase rate is larger or not, and the presence / absence of the overcurrent state is determined based on the comparison result, the overcurrent state caused by the lock state of the load can be easily and efficiently determined.
[0083]
  Claim5, Claims6, Claims14And claims15According to the invention described in the above, the drive current of the load is measured by the current sensor, the current decrease rate immediately after the peak current of the drive current is obtained based on the measurement result, and the current decrease rate is stored in advance. Since it is compared whether or not it is smaller than the normal current drop rate, the presence or absence of an overcurrent state is judged based on the comparison result., ContractClaim4And claims13In this case, the measured current after the peak current is obtained even if the current rise rate immediately after startup does not increase so much as it exceeds the current rise rate during normal startup. An overcurrent state can be reliably detected by having a small value attenuation.
[0084]
  Claim7And claims16According to the invention described in the above, since the drive current cutoff period is set differently from the cutoff period for cutting off the drive current for other purposes, it is possible to easily execute the optimum load restart for overcurrent protection. Can do.
[0085]
  Claim8, Claims9, Claims17And claims18When the compressor of the air conditioner is used as a load, the opening degree of the motor-operated valve for changing the refrigerant supply of the compressor is changed when the load is restarted after the drive current is cut off. Therefore, it is possible to efficiently supply the refrigerant after overcurrent protection.
[0086]
  Claim19According to the invention described in (1), since it is executed by a computer based on a program, special control at the time of starting and at the time of normal operation can be easily realized at low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overcurrent protection device according to an embodiment of the present invention.
FIG. 2 is a diagram showing a specific example of a starting reference current value and a normal operation reference current value in the overcurrent protection device according to one embodiment of the present invention.
FIG. 3 is a diagram showing a change in a measured current value during a starting period of a compressor.
FIG. 4 is a flowchart showing an overall flow of an overcurrent protection method according to an embodiment of the present invention.
FIG. 5 is a flowchart showing a comparison process between a measured current value and a reference current value in the overcurrent protection method according to the embodiment of the present invention.
FIG. 6 is a flowchart showing a current increase rate comparison process in the overcurrent protection method according to the embodiment of the present invention;
FIG. 7 is a flowchart showing a current drop rate comparison process in the overcurrent protection method according to the embodiment of the present invention;
FIG. 8 is a flowchart showing standby time setting processing in the overcurrent protection method according to one embodiment of the present invention;
[Explanation of symbols]
1 Current path
2 Current sensor
3 Current interrupter
4 Control unit
MC compressor (load)

Claims (19)

The drive current (I) of the load (MC) is measured, the reference current value is changed depending on whether the load is started or during normal operation, and the measured drive current is compared with the reference current value. The overcurrent operation determination time for determining the presence / absence of an overcurrent state based on the comparison result and for determining the presence / absence determination of the overcurrent state is shorter during the start-up period of the load than during normal operation. An overcurrent protection device. The overcurrent protection device according to claim 1,
An overcurrent protection device that cuts off the drive current (I) when it is determined that the current is in an overcurrent state. The overcurrent protection device according to claim 1 or 2,
A current sensor (2) for measuring a drive current (I) of the load (MC);
The reference current value is changed depending on whether the load is started or during normal operation, the drive current measured by the current sensor is compared with the reference current value, and the overcurrent state is based on the comparison result. An overcurrent protection device comprising: a control unit (4) that cuts off the drive current when it is determined whether or not an overcurrent state is present. The overcurrent protection device according to any one of claims 1 to 3,
A current increase rate of the drive current (I) immediately after starting the load (MC) is obtained, and whether or not the current increase rate is larger than a normal current increase rate stored in advance is compared, and the comparison result overcurrent protection device according to claim that you determine the presence or absence of overcurrent state based on. Determine the current decrease rate of the load peak current immediately after the driving current of (MC) (I), the current reduction rate, compares whether squid smaller than prestored to normal current decrease rate had, the comparison result An overcurrent protection device that determines the presence or absence of an overcurrent state based on The overcurrent protection device according to any one of claims 1 to 4,
The load determine the current decrease rate of the peak current after the drive current (I) of (MC), the current reduction rate, compares whether squid smaller than a predetermined normal current decrease rate that has been stored, the comparison An overcurrent protection device that determines the presence or absence of an overcurrent state based on a result. The overcurrent protection device according to any one of claims 1 to 6,
When the drive current (I) is cut off because it is in an overcurrent state, the cut-off period from when the drive current is cut off until the supply is restarted is when the drive current is cut off for other purposes. Overcurrent protection device characterized by being set differently . The overcurrent protection device according to any one of claims 1 to 7 ,
The load (MC) is an air conditioner compressor;
When the opening degree of the motor-operated valve for switching the refrigerant supply of the compressor cuts off the drive current (I), the supply of the drive current (I) is restarted, and the load is restarted. overcurrent protection device according to claim Rukoto different in the case of non. The overcurrent protection device according to claim 8 ,
The opening degree of the electronic expansion valve for refrigerant supply switching of the compressor in the case of restarting the previous SL said load to supply restart the drive current (I) after interrupting the driving current (I) is, the restart An overcurrent protection device characterized in that it is larger than other cases . The drive current (I) of the load (MC) is measured, the reference current value is changed depending on whether the load is started or during normal operation, and the drive current is compared with the reference current value. The overcurrent operation determination time for determining the presence or absence of an overcurrent state based on the result and determining the presence or absence of the overcurrent state is shorter during the start-up period of the load than during normal operation. Overcurrent protection method . The overcurrent protection method according to claim 10,
An overcurrent protection method comprising: cutting off the drive current (I) when it is determined that the current is in an overcurrent state . The overcurrent protection method according to claim 10 or 11,
A first step of measuring a drive current (I) of the load (MC) with a current sensor (2);
A second step of changing and setting a reference current value depending on whether the load is started or during normal operation;
A third process step of comparing the drive current measured by the current sensor against the reference current value and determining the presence or absence of an overcurrent state based on the comparison result;
A fourth step of cutting off the drive current when it is determined in the third step that an overcurrent state is present;
Over-current protection method of Ru with a. The overcurrent protection method according to any one of claims 10 to 14 ,
A current increase rate of the drive current (I) immediately after starting the load (MC) is obtained, and whether or not the current increase rate is larger than a normal current increase rate stored in advance is compared, and the comparison result An overcurrent protection method comprising determining whether or not an overcurrent state exists based on The current decrease rate of the drive current (I) immediately after the peak current of the load (MC) is obtained, and whether or not the current decrease rate is smaller than a normal current decrease rate stored in advance is compared. overcurrent protection how to characterized by determining the presence or absence of overcurrent state based on. An overcurrent protection method according to any one of claims 10 to 13 , comprising:
The current decrease rate of the drive current (I) immediately after the peak current of the load (MC) is obtained, and whether or not the current decrease rate is smaller than a normal current decrease rate stored in advance is compared. overcurrent protection method characterized that you determine the presence or absence of overcurrent state based on the result. The overcurrent protection method according to any one of claims 10 to 15,
When the supply of the drive current (I) is restarted after the drive current (I) is cut off due to being in the overcurrent state and the load is restarted, the drive current is cut off until the supply is restarted The overcurrent protection method is characterized in that the interruption period is set differently from the interruption period in which the drive current is interrupted for other purposes . The overcurrent protection method according to any one of claims 10 to 16 , comprising:
The load (MC) is an air conditioner compressor;
When the opening degree of the motor-operated valve for switching the refrigerant supply of the compressor cuts off the drive current (I), the supply of the drive current (I) is restarted, and the load is restarted. overcurrent protection method comprising Rukoto different in the case of non. The overcurrent protection method according to claim 17,
When the driving current (I) is cut off and the supply of the driving current (I) is restarted to restart the load, the opening of the motor-operated valve for switching the refrigerant supply of the compressor is other than the restarting. An overcurrent protection method characterized by being larger than The program which implement | achieves the overcurrent protection method in any one of Claim 10 thru | or 17 by running by a computer.

Images