JP6489548B2 - Power converter, air conditioning system, power converter control method and program - Google Patents

Description

  The present invention relates to a power conversion device, an air conditioning system, a control method for the power conversion device, and a program.

  An inverter (power converter) that is installed in an air conditioning system, etc., that drives a motor-driven compressor by converting direct current to alternating current detects the overcurrent for some reason and immediately starts power conversion. It has a shutdown function to stop (specifically, switching operation by the switching element). The inverter determines, for example, the voltage generated between the terminals of the current detection shunt resistor using a comparator circuit, and when the detected voltage exceeds a predetermined determination threshold, the signal is input to the shutdown signal input terminal of the gate driver. Will be stopped.

  In addition, as a technology related to this, the current and the amount of change in the current are grasped by the voltage between the terminals of the resistor and the voltage between the terminals of the coil. Has been disclosed (see Patent Document 1).

JP 2012-066549 A

There are two possible causes of overcurrent in the power converter described above, for example, “upper and lower arm series short circuit” and “short circuit via motor”. Here, if the cause of the overcurrent is “short circuit via the motor”, there is a possibility of erroneous detection of the overcurrent (temporary factor), and it may operate normally by restarting. is assumed.
On the other hand, when the cause of the overcurrent is “upper and lower arm series short circuit”, it is assumed that the switching element is broken or broken. When the power conversion device is restarted in such a state, an overcurrent flows again in the power conversion device, and the failure may be further deteriorated due to excessive stress. Therefore, in this case, operation should not be resumed.

However, the above-described overcurrent detection method cannot distinguish whether the overcurrent is based on “upper and lower arm series short circuit” or “short circuit via a motor”. Therefore, even if it is the case of either “upper and lower arm series short circuit” or “short circuit via motor”, once an overcurrent is detected, a permanent stop process is performed to limit the restart by the user. The
Therefore, even if the cause of the overcurrent is “short circuit via the motor” and it actually operates normally if it is restarted, the user itself cannot be restarted uniformly. There were many complaints from customers.

  The present invention has been made in view of the above problems, and its purpose is to provide a power conversion device, an air conditioning system, and an air conditioning system capable of appropriately limiting restart by a user when an overcurrent is detected. An object of the present invention is to provide a control method and program for a power converter.

  One aspect of the present invention is a power conversion device that drives an AC motor by converting power from direct current to alternating current, and for determining a voltage value for determination according to both the current and the amount of change in the current. A voltage detection unit, an operation stop instructing unit for instructing to stop operation of the power conversion when the determination voltage value exceeds a first determination threshold value, and the determination voltage value is greater than the first determination threshold value And a permanent stop processing unit configured to perform a permanent stop process for restricting the restart of the power conversion operation after the stop of the power conversion operation when the second determination threshold value is exceeded.

  The power conversion device according to one aspect of the present invention may further include a restart instruction unit that instructs to resume operation of the power conversion when the determination voltage value is equal to or less than the second determination threshold value. Prepare.

  In the aspect of the present invention, the restart instruction unit repeats an instruction to restart the power conversion operation a predetermined number of times after the power conversion operation is stopped.

  In addition, the power conversion device according to one aspect of the present invention includes a hold unit that holds the determination voltage value after a predetermined time has elapsed since the determination voltage value exceeds a first determination threshold value, and the hold And a determination unit that determines whether or not the hold value held by the unit exceeds the second determination threshold value.

  In the aspect of the invention, the determination voltage detection unit is an element including an inductance component and a resistance component.

  Another embodiment of the present invention is an air conditioning system including the power conversion device described above and a compressor having the AC motor driven by AC power supplied from the power conversion device.

  One embodiment of the present invention includes a determination voltage detection unit that detects a determination voltage value corresponding to both the current and the amount of change in the current, and drives the AC motor by converting power from DC to AC. A method for controlling the power conversion device to perform the step of instructing the operation stop of the power conversion when the determination voltage value exceeds a first determination threshold value, and the determination voltage value is the first determination threshold value. And a step of performing a permanent stop process for restricting the restart of the power conversion operation after the operation stop of the power conversion when the second determination threshold value is larger than the second determination threshold value.

  One embodiment of the present invention includes a determination voltage detection unit that detects a determination voltage value corresponding to both the current and the amount of change in the current, and drives the AC motor by converting power from DC to AC. When the determination voltage value exceeds a first determination threshold, the computer of the power conversion device to be operated is an operation stop instruction means for instructing stop of the power conversion operation, and the determination voltage value is greater than the first determination threshold. Is a program that functions as a permanent stop processing means for performing a permanent stop process for restricting the restart of the power conversion operation after the power conversion operation is stopped.

  According to the above-described power conversion device, air conditioning system, power conversion device control method, and program, when an overcurrent is detected, the user can appropriately limit the restart.

It is a figure which shows the whole structure of the power converter device which concerns on 1st Embodiment. It is a figure which shows the function structure of the control part which concerns on 1st Embodiment. It is a 1st figure explaining the factor of the overcurrent which may occur in the power converter concerning a 1st embodiment. It is a 2nd figure explaining the factor of the overcurrent which may arise in the power converter device concerning a 1st embodiment. It is a figure explaining the characteristic of the overcurrent which can occur in the power converter device concerning a 1st embodiment. It is a figure explaining the characteristic of the shunt voltage value which concerns on 1st Embodiment. It is a figure which shows the processing flow of the control part which concerns on 1st Embodiment. It is a figure which shows the whole structure of the power converter device which concerns on 2nd Embodiment. It is a figure explaining the characteristic of the shunt voltage value which concerns on 2nd Embodiment.

<First Embodiment>
Hereinafter, the power converter according to the first embodiment will be described with reference to FIGS.

(overall structure)
FIG. 1 is a diagram illustrating an overall configuration of the power conversion device according to the first embodiment.
As shown in FIG. 1, the power conversion device 1 is an inverter that converts DC power supplied from the storage battery 3 into three-phase AC power and drives an AC motor 2 that is a load. Here, the AC motor 2 is an electric motor that is driven by three-phase AC power supplied from the power converter 1.

  The power converter 1, AC motor 2, and storage battery 3 according to the first embodiment are used in an air conditioning system (car air conditioner) mounted on a vehicle. In this case, AC motor 2 drives the compressor (compressor) of the air conditioning system. The storage battery 3 is a battery mounted on the vehicle.

  As shown in FIG. 1, the power conversion device 1 includes a control unit 10, a power conversion circuit 11, a shunt resistor element 12 (determination voltage detection unit), a reference voltage output unit 13, and a comparator 14. ing.

The control unit 10 governs the overall operation of the power conversion device 1. In particular, the control unit 10 functions as a gate driver that outputs a drive signal to a power conversion circuit 11 (described later) to control the drive. The control unit 10 is realized by, for example, a microcomputer.
Specific functions of the control unit 10 will be described in detail with reference to FIG.

The power conversion circuit 11 converts the DC power supplied from the storage battery 3 into three-phase AC power by being driven based on a control signal from the control unit 10. Here, the power conversion circuit 11 includes six switching elements SW. Each switching element SW is switched between an ON state in which a current flows and an OFF state in which the current is interrupted based on a drive signal (gate input) from the control unit 10. Corresponding to each of the U-phase, V-phase, and W-phase forming a three-phase alternating current, two switching elements SW are respectively connected to a high potential line α (wiring to which the high potential side of the storage battery 3 is connected) and a low potential line β It is connected in series with the shunt resistance element 12 (wiring grounded through a later-described). By switching each switching element SW ON / OFF at a prescribed timing, three-phase (U-phase, V-phase, W-phase) AC power is supplied to the AC motor 2.
The switching element SW is typically an IGBT (Insulated Gate Bipolar Transistor), but may be a bipolar transistor, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), or the like.

The shunt resistance element 12 is a resistance element inserted between the power conversion circuit 11 and the ground point. The shunt resistance element 12 is provided for the purpose of detecting a current (motor current) required to drive the AC motor 2. Specifically, a voltage drop corresponding to the motor current occurs between the terminals of the shunt resistor element 12. The motor current can be detected by reading the shunt voltage value Vsh (determination voltage value) which is the voltage between the terminals.
Actually, the shunt resistance element 12 includes not only the resistance component 12b as a resistance element but also an inductance component 12a floating on the resistance component 12b. In this case, the circuit diagram of the shunt resistance element 12 is equivalent to a circuit in which an inductance component 12a and a resistance component 12b are connected in series as shown in FIG.
In the present embodiment, the resistance component 12b is about 1 mΩ to 10 mΩ, and the inductance component 12a is about 20 nH to 40 nH.

  The reference voltage output unit 13 outputs a predetermined reference voltage. The reference voltage output by the reference voltage output unit 13 corresponds to a first determination threshold value Vt1 described later.

  The comparator 14 receives the shunt voltage value Vsh and the first determination threshold value Vt1 that is the reference voltage, and outputs a determination signal corresponding to the magnitude relationship between the shunt voltage value Vsh and the first determination threshold value Vt1. For example, the comparator 14 outputs a determination signal “High” when the shunt voltage value Vsh exceeds the first determination threshold value Vt1, and the determination signal “Low” when the shunt voltage value Vsh is equal to or less than the first determination threshold value Vt1. "Is output.

(Functional configuration of control unit)
FIG. 2 is a diagram illustrating a functional configuration of the control unit according to the first embodiment.
As illustrated in FIG. 2, the control unit 10 includes a power conversion drive control unit 100, an operation stop instruction unit 101, a determination unit 102, a permanent stop processing unit 103, and a restart instruction unit 104. .

The power conversion drive control unit 100 outputs a drive signal to each switching element SW (FIG. 1) constituting the power conversion circuit 11 (FIG. 1) and performs power conversion from direct current to alternating current.
The operation stop instruction unit 101 instructs the power conversion drive control unit 100 to stop the power conversion when the detected shunt voltage value Vsh exceeds a predetermined first determination threshold value Vt1.
The determination unit 102 determines whether or not the detected shunt voltage value Vsh exceeds the second determination threshold value Vt2 that is larger than the first determination threshold value Vt1 after the operation stop instruction unit 101 stops the power conversion operation. .
As a result of the determination by the determination unit 102, the permanent stop processing unit 103 performs a permanent stop process that restricts the restart (restart) of power conversion when the shunt voltage value Vsh exceeds the second determination threshold value Vt2.
When the determination by the determination unit 102 indicates that the shunt voltage value Vsh is equal to or less than the second determination threshold value Vt2, the restart instruction unit 104 restarts the power conversion operation (restart) with respect to the power conversion drive control unit 100. Instruct.

(Cause of overcurrent)
FIG. 3 is a first diagram for explaining factors of overcurrent that may occur in the power conversion device according to the first embodiment.
FIG. 4 is a second diagram for explaining the cause of overcurrent that may occur in the power conversion device according to the first embodiment.
FIG. 3 shows an example in the case where an overcurrent occurs in the power conversion device 1 due to “upper and lower arm series short circuit”. The overcurrent caused by the “upper and lower arm series short circuit” refers to an overcurrent generated when the high potential line α and the low potential line β are short-circuited through the switching element SW constituting the power conversion circuit 11.
Here, during normal operation of the power conversion device 1, at least one of the two switching elements SW connected in series between the high potential line α and the low potential line β of the power conversion circuit 11 is at least one of them. It is controlled to be “OFF”. Therefore, during normal operation, the high potential line α and the low potential line β of the power conversion circuit 11 are not short-circuited. However, when any switching element SW fails and “OFF” does not function, the high potential line α and the low potential line β are short-circuited through the switching element SW.
Specifically, as shown in FIG. 3, the high potential line α is applied to the low potential line β through the two switching elements SW connected in series between the high potential line α and the low potential line β. Overcurrent Io1 caused by “upper and lower arm series short circuit” flows.

FIG. 4 shows an example in the case where an overcurrent occurs in the power conversion device 1 due to “short circuit via the motor”. The overcurrent caused by the “short circuit via the motor” refers to an overcurrent generated when the high potential line α and the low potential line β are short-circuited through the AC motor 2 serving as the load of the power conversion device 1. Point to.
The overcurrent caused by the “short circuit via the motor” is, for example, when an overload state occurs due to the rotational drive of the AC motor 2 being locked due to mechanical factors, or from the control unit 10 (FIG. 1). This occurs when noise is superimposed on the drive signal and the switching element SW malfunctions.
Specifically, as shown in FIG. 4, the overcurrent Io2 caused by the “short circuit via the motor” is generated from the high potential line α to the low potential line β through the coil 20 mounted inside the AC motor 2. Flowing.

(Overcurrent characteristics)
FIG. 5 is a diagram for explaining characteristics of overcurrent that may occur in the power conversion device according to the first embodiment.
The graph shown in FIG. 5 shows the change over time of the current flowing through the shunt resistance element 12. In FIG. 5, the graph indicated by the solid line shows the transition of the current when the overcurrent Io1 caused by the “upper and lower arm series short circuit” occurs at time t1. Further, the graph indicated by the broken line shows the transition of the current when the overcurrent Io2 due to the “short circuit via the motor” occurs at the time t1.

Here, when the “upper and lower arm series short circuit” occurs, the high potential line α and the low potential line β are directly shorted via the switching element SW (see FIG. 3). The overcurrent Io1 due to “” changes extremely abruptly.
On the other hand, when the “short circuit via the motor” occurs, the high potential line α and the low potential line β are short-circuited via the coil 20 inside the AC motor 2 (see FIG. 4). The overcurrent Io2 resulting from the “short circuit via” is suppressed relatively transiently by the coil 20 and changes relatively slowly.
Therefore, as shown in FIG. 5, the overcurrent Io1 caused by the “upper and lower arm series short circuit” increases more rapidly than the overcurrent Io2 caused by the “short circuit via the motor”.

(Characteristics of shunt voltage value)
FIG. 6 is a diagram for explaining the characteristics of the shunt voltage value according to the first embodiment.
The graph shown in FIG. 6 shows the change over time of the shunt voltage value Vsh generated between the terminals of the shunt resistor element 12. In FIG. 6, the graph indicated by the solid line shows the transition of the shunt voltage value Vsh1 that occurs when the overcurrent Io1 caused by the “upper and lower arm series short circuit” flows at time t1. Further, the graph indicated by a broken line shows the transition of the shunt voltage value Vsh2 that occurs when the overcurrent Io2 caused by the “short circuit via the motor” flows at time t1.

As described above, the shunt resistance element 12 according to the present embodiment has the floating inductance component 12a and the resistance component 12b as the resistance element (see FIG. 1). Here, when the inductance of the inductance component 12a is “L”, the voltage VL generated between the terminals of the inductance component 12a is “VL = L · di / dt”. Here, “di / dt” is a transient change amount of the current (overcurrent Io1, Io2) flowing through the inductance component 12a.
When the resistance value of the resistance component 12b is “R”, the voltage VR generated between the terminals of the resistance component 12b is “VR = R · I”. Here, “I” is a current (overcurrent Io1, Io2) flowing through the resistance component 12b.
Therefore, the shunt voltage value Vsh generated between the terminals of the shunt resistor element 12 is expressed by the following formula (1).

  Vsh = VL + VR = L · di / dt + R · I (1)

  As described above, the shunt resistance element 12 detects the shunt voltage value Vsh corresponding to both the current “I” and the current variation “di / dt”.

  Therefore, when the overcurrents Io1 and Io2 flow at time t1, the shunt voltage value Vsh changes as shown in FIG. 6 based on the current “I” and the current change amount “di / dt”. That is, since the current change amount “di / dt” becomes the largest at the time t1 when the overcurrents Io1 and Io2 occur, the shunt voltage value Vsh instantaneously rises at the time t1 based on the “VL”. . Further, the shunt voltage value Vsh also rises due to the current values of the overcurrents Io1 and Io2 based on the above “VR” (see Expression (1)).

  However, as described above, the overcurrent Io1 caused by the “upper and lower arm series short circuit” fluctuates more rapidly than the overcurrent Io2 caused by the “short circuit via the motor”. The amount of current change “di / dt” increases. Therefore, immediately after time t1, the shunt voltage value Vsh1 becomes larger than the shunt voltage value Vsh2 by the amount of change in current “di / dt”.

As shown in FIG. 6, the first determination threshold value Vt1 depends on the shunt voltage value Vsh1 generated in response to the overcurrent Io1 due to “upper and lower arm series short circuit” and the overcurrent Io2 due to “short circuit via the motor”. All of the generated shunt voltage values Vsh2 are defined in advance to exceed the first determination threshold value Vt1 at time t1.
On the other hand, the second determination threshold value Vt2 is defined in advance so that only the shunt voltage value Vsh1 generated according to the overcurrent Io1 due to the “upper and lower arm series short circuit” exceeds the second determination threshold value Vt2 at time t1.

(Processing flow of the control unit)
FIG. 7 is a diagram illustrating a processing flow of the control unit according to the first embodiment.
The processing flow of the control unit 10 illustrated in FIG. 7 is started from a stage before the power conversion device 1 is activated.
First, the power conversion drive control unit 100 of the control unit 10 drives the power conversion circuit 11 in accordance with an external instruction or the like, and starts a power conversion operation (step S01). During the power conversion operation by the power conversion drive control unit 100, the DC power of the storage battery 3 is converted into three-phase AC power and supplied to the AC motor 2. Therefore, after step S01, normal operation as an air conditioning system is performed.

  During normal operation, the operation stop instruction unit 101 constantly monitors whether or not the shunt voltage value Vsh exceeds the first determination threshold value Vt1 based on the determination signal from the comparator 14 (FIG. 1) (step) S02). Here, when the determination signal from the comparator 14 is “Low” (that is, when the shunt voltage value Vsh is equal to or lower than the first determination threshold value Vt1 (step S02: NO)), the operation stop instruction unit 101 detects an overcurrent. It is assumed that the system is operating normally without any problems, and no processing is performed. Therefore, the power conversion drive control unit 100 continues normal operation.

  On the other hand, when the determination signal from the comparator 14 is “High” (that is, when the shunt voltage value Vsh exceeds the first determination threshold value Vt1 (step S02: YES)), the operation stop instructing unit 101 receives the overcurrent. The power conversion drive control unit 100 is instructed to stop operation immediately. Receiving the instruction to stop the operation, the power conversion drive control unit 100 urgently stops the operation of power conversion (step S03).

After the emergency stop by the operation stop instruction unit 101, the determination unit 102 determines whether or not the shunt voltage value Vsh at the time when the first determination threshold value Vt1 exceeds the second determination threshold value Vt2 (step S1) S04).
Here, when the shunt voltage value Vsh further exceeds the second determination threshold value Vt2 (step S04: YES), the detected overcurrent is large because the current change amount “di / dt” is large. It is assumed that this occurred due to “short circuit” (see FIG. 6). Therefore, the permanent stop process part 103 performs the permanent stop process which restrict | limits restart of the power converter device 1 (step S07).
Thereby, the power converter device 1 will be in a "permanent stop state", and the restart by the user of an air conditioning system is restrict | limited. Therefore, it is possible to prevent the occurrence or progress of further failure in the power conversion device 1.

On the other hand, when the shunt voltage value Vsh is further equal to or smaller than the second determination threshold value Vt2 (step S04: NO), since the amount of change “di / dt” of the current is small, the detected overcurrent is “via the motor. It is assumed that this occurred due to “short circuit” (see FIG. 6). In this case, the restart instruction unit 104 first counts up the restart count N (initial value is “0”) (step S05), and the restart count N is a predetermined specified count Nth (for example, “5”). ) Is determined (step S06).
When the number N of restarts is equal to or less than the specified number Nth, the restart instruction unit 104 instructs the power conversion drive control unit 100 to restart operation of power conversion. Thereby, the operation | movement of the power conversion by the power conversion drive control part 100 is restarted (step S01).
As a result, when it is determined that the detected overcurrent is caused by “a short circuit via the motor”, the restart instruction unit 104 attempts to restart. Therefore, when the cause of the overcurrent is transient, normal operation is automatically resumed.

On the other hand, when the number N of restarts exceeds the specified number Nth, the permanent stop processing unit 103 performs a permanent stop process that limits the restart of the power conversion device 1 (step S07). Here, even if the overcurrent occurs due to the “short circuit via the motor”, the cause may not be transient. Therefore, as a result of attempting to restart a plurality of times (for example, 5 times), if any overcurrent is detected (step S02: YES) and the emergency stop is performed, there is a permanent failure factor in the power converter 1. It is determined that a permanent stop process is to be performed.
If the restart instruction unit 104 restarts normally while trying to restart a plurality of times (for example, five times) (step S02: NO), the restart number N is reset to the initial value.

(Function and effect)
As described above, according to the power conversion device 1 according to the first embodiment, when the shunt voltage value Vsh corresponding to both the current and the amount of change in the current exceeds the first determination threshold value Vt1, the operation stop instruction unit 101 instruct | indicates the operation stop of power conversion. Then, when the shunt voltage value Vsh exceeds the second determination threshold value Vt2 that is larger than the first determination threshold value Vt1, the permanent stop processing unit 103 limits the restart of power conversion operation after the power conversion operation stop. Apply processing.
Thus, even when the shunt voltage value Vsh exceeds the first determination threshold value Vt1 and an overcurrent is detected, the shunt voltage value Vsh is permanent only when the overcurrent exceeds the second determination threshold value Vt2. Stop processing is performed. Therefore, if the restart is attempted, the permanent stop process is not performed until the possibility of normal operation is high, so that the user can restart the operation as desired. That is, when an overcurrent is detected, it is possible to appropriately limit the restart by the user.

Moreover, according to the power converter device 1 which concerns on 1st Embodiment, when the shunt voltage value Vsh is below a 2nd determination threshold value, the restart instruction | indication part 104 instruct | indicates the driving | operation restart of power conversion.
By doing in this way, even if an overcurrent is detected and an emergency stop is performed, if there is a high possibility of normal operation if a restart is attempted, the restart is automatically performed. Therefore, it is possible to reduce time and effort for the user to operate for restarting.

Moreover, according to the power converter device 1 which concerns on 1st Embodiment, the restart instruction | indication part 104 repeats the instruction | indication of restart only for the predetermined times (specified number Nth) prescribed | regulated after the operation | movement stop of power conversion. .
In this way, when an overcurrent due to a “short circuit via the motor” is assumed, it can be determined whether the cause is transient or not, and appropriate processing should be performed. Can do. For example, when an overcurrent is detected over a plurality of restarts, it is determined that there is no expectation of normal operation, and the user can be prevented from starting through a permanent stop process.

Moreover, according to the power converter device 1 according to the first embodiment, the shunt resistance element 12 is a single element including an inductance component and a resistance component.
By doing so, the degree to which the shunt voltage value Vsh changes depending on the current change amount “di / dt” increases, so the cause of the overcurrent is “upper and lower arm series short circuit” or “through the motor Can be accurately identified. Further, since only a single element (shunt resistor element 12) needs to be provided, the number of components to be mounted can be reduced, and downsizing and cost reduction can be achieved.

In step S04 of the processing flow (FIG. 7) of the control unit 10 according to the first embodiment, the determination unit 102 determines whether or not the shunt voltage value Vsh at time t1 further exceeds the second determination threshold value Vt2. The following modes can be considered as specific means for determining.
For example, apart from the reference voltage output unit 13 (FIG. 1) and the comparator 14 (FIG. 1), the same reference voltage output unit and comparator are provided, and the reference voltage output unit is set to the second determination threshold value Vt2. It is good also as an aspect which outputs a corresponding reference voltage. In this case, the determination unit 102 determines whether or not the shunt voltage value Vsh exceeds the second determination threshold based on the determination signal from the comparator that compares the second determination threshold Vt2 (step S04). .
Further, the determination unit 102 acquires the sampling value of the shunt resistance value Vsh through a separately provided A / D converter, and refers to the sampling value acquired at the corresponding time (time t1), thereby performing the determination process. You may go.

<Second Embodiment>
Next, a power conversion device according to the second embodiment will be described with reference to FIGS. 8 and 9.

(overall structure)
FIG. 8 is a diagram illustrating an overall configuration of a power conversion device according to the second embodiment.
In FIG. 8, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As illustrated in FIG. 8, the power conversion device 1 according to the second embodiment includes a hold unit 15.
The hold unit 15 holds the shunt voltage value Vsh after a predetermined time has elapsed since the shunt voltage value Vsh exceeded the first determination threshold value Vth. Specifically, using the determination signal “High” input from the comparator 14 as a trigger, the shunt voltage value Vsh after the elapse of a predetermined time is acquired and held.

  The functional configuration of the control unit 10 according to the second embodiment is the same as that of the first embodiment, and a detailed description thereof is omitted. However, the determination unit 102 (FIG. 2) according to the second embodiment receives an input of the hold value Vhold from the hold unit 15, and the hold value Vhold held by the hold unit 15 exceeds the second determination threshold value Vth2. It is determined whether or not.

FIG. 9 is a diagram for explaining the characteristics of the shunt voltage value according to the second embodiment.
The graph shown in FIG. 9 shows the change over time of the shunt voltage value Vsh generated between the terminals of the shunt resistor element 12. In FIG. 9, the graph indicated by the solid line shows the transition of the shunt voltage value Vsh1 that occurs when the overcurrent Io1 caused by the “upper and lower arm series short circuit” flows at time t1. Further, the graph indicated by a broken line shows the transition of the shunt voltage value Vsh2 that occurs when the overcurrent Io2 caused by the “short circuit via the motor” flows at time t1.

When the hold unit 15 according to the second embodiment receives the determination signal “High” from the comparator 14 which is an overcurrent detection signal at time t1, the hold unit 15 receives the shunt voltage at time t2 after elapse of a predetermined time from the time t1. Processing for holding the value Vsh is performed (see FIG. 9). On the other hand, the operation stop instruction unit 101 (FIG. 2) instructs the power conversion drive control unit 100 to stop operation based on the determination signal “High” from the comparator 14 (see step S03 in FIG. 7).
Here, as a result of the operation stop instruction by the operation stop instruction unit 101, the power conversion drive control unit 100 actually stops the operation. At time t3, no overcurrent flows (see FIG. 9). The hold unit 15 holds the shunt voltage value Vsh from the time t1 at which the determination signal “High” is received to the time t3 at which the emergency stop is actually performed by the operation stop instruction unit 101 and the power conversion drive control unit 100. (That is, there is a relationship of time t1 <time t2 <time t3).
As in the first embodiment, the shunt voltage value Vsh1 and the shunt voltage value vsh2 have a potential difference corresponding to the current change amount “di / dt” at the time t1 when the overcurrent is detected. This potential difference is maintained even at time t2 after a predetermined time has elapsed from time t1.

  The determination unit 102 acquires the hold value Vhold (that is, the shunt voltage value Vsh at time t2) held by the hold unit 15 in step S04 (FIG. 7), and the hold value Vhold sets the second determination threshold value Vt2. It is determined whether or not it exceeds.

  As described above, the power conversion device 1 according to the second embodiment has the hold unit 15 separately, so that it is possible to accurately isolate the cause of the overcurrent (whether or not the determination threshold Vt2 is exceeded) with a simple circuit configuration. Determination).

(Modification of each embodiment)
As mentioned above , although the power converter device 1 concerning 1st, 2nd embodiment was demonstrated in detail, the specific aspect of the power converter device 1 is not limited to the above-mentioned thing, The range which does not deviate from a summary. It is possible to make various design changes and so on.

For example, in the power conversion devices 1 according to the first and second embodiments, when the shunt voltage value Vsh is equal to or less than the second determination threshold value Vt2, the restart instruction unit 104 instructs the restart of power conversion operation. However, the present invention is not limited to this aspect in other embodiments.
For example, the power conversion device 1 does not automatically restart operation when the shunt voltage value Vsh is equal to or lower than the second determination threshold value Vt2, but simply urges the user to perform a restart operation. May be.

In the power conversion device 1 according to the first and second embodiments, the inductance component 12a is used as a determination voltage detection unit that detects a determination voltage value according to both the current and the amount of change in the current. However, in the other embodiments, the present invention is not limited to this mode.
In the power conversion device 1 according to another embodiment, the determination voltage detection unit may be, for example, an aspect in which a resistance element and an inductance element are connected in series.

In each of the above-described embodiments, a program for realizing various functions of the control unit 10 of the power conversion device 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is stored in a computer system. It is assumed that various processes are performed by reading and executing. Here, the process of the various processes of the control unit 10 described above is stored in a computer-readable recording medium in the form of a program, and the above-described various processes are performed by the computer reading and executing the program. The computer-readable recording medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.
The control unit 10 is not limited to a mode in which various functional configurations are housed in a single device housing, and the various functional configurations of the control unit 10 are provided over a plurality of devices connected via a network. An aspect may be sufficient.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof, as long as they are included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 1 Power converter 10 Control part 100 Power conversion drive control part 101 Operation stop instruction | indication part 102 Determination part 103 Permanent stop process part 104 Restart instruction | indication part 11 Power conversion circuit 12 Shunt resistance element (voltage detection part for determination)
12a Inductance component 12b Resistance component 13 Reference voltage output unit 14 Comparator 15 Hold unit 2 AC motor 20 Coil 3 Storage battery SW Switching element

Claims (6)

A power conversion device that converts power from direct current to alternating current to drive an alternating current motor,
An element including an inductance component and a resistance component, and a determination voltage detection unit that detects a determination voltage value according to both the current and the amount of change in the current;
An operation stop instructing unit for instructing to stop operation of the power conversion when the voltage value for determination exceeds a first determination threshold;
When the voltage value for determination exceeds a second determination threshold value that is larger than the first determination threshold value, a permanent stop process for performing a permanent stop process for restricting restart of the power conversion operation after the operation stop of the power conversion is performed. And
A hold unit that holds the determination voltage value after a predetermined time has elapsed since the determination voltage value exceeded a first determination threshold;
A determination unit that determines whether or not a hold value held by the hold unit exceeds the second determination threshold;
A power conversion device comprising: The power conversion device according to claim 1, further comprising a restart instruction unit that instructs resumption of operation of the power conversion when the determination voltage value is equal to or less than the second determination threshold value. The restart instruction unit
The power conversion device according to claim 2, wherein after the power conversion operation is stopped, an instruction to restart the power conversion operation is repeated a predetermined number of times specified in advance. The power conversion device according to any one of claims 1 to 3 ,
A compressor having the AC motor driven by AC power supplied from the power converter;
Air conditioning system equipped with. An element that includes an inductance component and a resistance component, and includes a determination voltage detection unit that detects a determination voltage value according to both the current and the amount of change in the current, and converts power from DC to AC. A method for controlling a power converter for driving an AC motor,
Instructing the operation stop of the power conversion when the determination voltage value exceeds a first determination threshold;
When the determination voltage value exceeds a second determination threshold value that is greater than the first determination threshold value, after the operation of the power conversion is stopped, a step of performing a permanent stop process for limiting the restart of the power conversion operation;
Holding the determination voltage value after a predetermined time has elapsed since the determination voltage value exceeded a first determination threshold;
Determining whether or not the held value held in the step of holding the voltage value for determination exceeds the second determination threshold;
A control method for a power conversion device having An element that includes an inductance component and a resistance component, and includes a determination voltage detection unit that detects a determination voltage value according to both the current and the amount of change in the current, and converts power from DC to AC. A computer of a power conversion device that drives an AC motor,
An operation stop instruction means for instructing to stop the operation of the power conversion when the voltage value for determination exceeds a first determination threshold;
When the voltage value for determination exceeds a second determination threshold value that is larger than the first determination threshold value, a permanent stop process for performing a permanent stop process for restricting restart of the power conversion operation after the operation stop of the power conversion is performed. means,
Holding means for holding the determination voltage value after a predetermined time has elapsed since the determination voltage value exceeded a first determination threshold;
Determination means for determining whether or not a hold value held by the hold means exceeds the second determination threshold;
Program to function as.

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