JPH1014267A - Starting controller for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain stable starting and positive detection of locking for a motor by utilizing the torque of a power conversion circuit to its maximum within such a range as breakage and burning of the motor and the power conversion can be prevented, even if the load torque is large. SOLUTION: If at the time of starting of a motor CM, an inverter output current I exceeds, the first setting value I1 which is a protective upper limit based on time limit characteristic for protecting the motor CM and power transistors Tr, Tr,..., a rising signal is outputted. If the rising signal is outputted further, an operating signal continues to be outputted to an inverter circuit 23, and when the inverter output current I is higher than the first setting value I1 and exceeds the second setting value [2 which is a protective upper limit, based on time limit characteristic for protecting the power transistors Tr, Tr,..., the output of the inverter circuit 23 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting control device for an electric motor, and more particularly, to a measure against a torque increase at the time of starting.

[0002]

2. Description of the Related Art Conventionally, a control device for controlling a compressor motor of an air conditioner is configured to supply control power to a compressor motor from a power supply via a rectifier circuit, a smoothing circuit, and an inverter circuit. There is.

When the motor is started, in a normal state, as shown in FIG. 5A, an output current I (hereinafter, referred to as an inverter output current I) supplied from the inverter circuit to the compressor motor gradually increases. It will be accelerated.

On the other hand, in the above-mentioned control device, a protection upper limit value I1, based on a time limit characteristic, that is, a rated current value is set to protect the compressor motor and the inverter element. When the inverter output current I reaches the protection upper limit I1, the acceleration is stopped and the inverter output current I is held at the protection upper limit I1 until a predetermined time TM31 elapses, as shown in FIGS. 5B and 5C. .

[0005] Further, as shown in FIG.
If the inverter output current I decreases before the elapse of TM31, the operation returns to the normal operation. On the other hand, as shown in FIG. 5C, if the inverter output current I does not decrease until the predetermined time TM3 elapses, the compressor motor locks. And the operation was stopped.

[0006]

In the control device for an air conditioner described above, only one protection upper limit value I1 is set. Therefore, only the torque corresponding to the inverter output current I of this protection upper limit value I1 is set. There was a problem that the compressor could not be obtained and the compressor could not be started stably.

That is, when the refrigerant is stagnated in the compressor, when the differential pressure between the discharge side and the suction side of the compressor is large,
If the starting torque is increased, such as when dust is stuck in the rotating part of the compressor, there is a problem in that even if there is a case where the compressor starts smoothly and shifts to normal operation, it is determined to be locked and the operation is stopped. there were.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. Sho 59-106881, during startup, even if the inverter output current I exceeds the protection upper limit I1, the supply frequency to the compressor motor is maintained for a while. Some are designed to provide smooth acceleration without lowering.

However, in this method, when the inverter output current I reaches the protection upper limit value I1, the decrease of the supply frequency is simply delayed, and the torque is not positively increased. As described above, there is a problem that when the load torque is large, such as when the refrigerant stagnates, stable starting cannot be performed.

[0010] The present invention has been made in view of the above points, and maximizes the torque of a power conversion circuit within a range where damage and burnout of an electric motor and a power conversion circuit can be prevented even when load torque is large. It is an object of the present invention to make it possible to perform a stable start-up by using the motor and to surely detect a lock of the electric motor.

[0011]

[Means for Solving the Problems]

−Summary of the Invention− The present invention provides a power conversion circuit (2) when a motor (CM) is started.
0) is output by the motor (CM) and the power conversion circuit (2).
0), a rising signal is output when the value exceeds a first set value I1 which is a protection upper limit based on a time limit characteristic for protecting the control element (Tr, Tr,...). Further, when the rising signal is output, an operation continuation signal is output to the drive circuit (31) of the power conversion circuit (20), and the output current I of the power conversion circuit (20) is changed to the first set value. If the set value is higher than I1 and exceeds a second set value I2 which is a protection upper limit based on an instantaneous characteristic for protecting the control elements (Tr, Tr,...) Of the power conversion circuit (20), the drive circuit (31 ) To output a stop signal.

-Specific Items of the Invention- Specifically, as shown in FIG. 1, means taken by the invention according to claim 1 first includes a power supply (PS) and a motor (CM), while the power supply (CM) is provided. A power conversion circuit (20) that converts the power supplied from the PS) into a predetermined control power and outputs the control power to a motor (CM); and a drive circuit (31) that outputs a drive signal to the power conversion circuit (20). And a current detecting means (CT) for detecting an output current I output from the power conversion circuit (20) to the electric motor (CM). Further, when the motor (CM) is started, the current detection means (CT) detects the power conversion circuit (2
0) is output by the motor (CM) and the power conversion circuit (2).
0) is determined to have exceeded a first set value I1, which is a protection upper limit value based on a time limit characteristic for protecting the control element (Tr, Tr,...), And the output current I is set to the first set value I1. A determination means (43) for outputting an ascending signal when the value exceeds. In addition, when the discriminating means (43) outputs a rising signal, it outputs a driving continuation signal to the drive circuit (31),
The output current I of the power conversion circuit (20) is the first set value I
It is determined whether the set value is higher than 1 and exceeds a second set value I2 which is a protection upper limit based on an instantaneous characteristic for protecting the control element (Tr, Tr,...) Of the power conversion circuit (20). And
A drive stop means (44) for outputting a stop signal to the drive circuit (31) when the output current I exceeds the second set value I2.

According to a second aspect of the present invention, in the first aspect of the present invention, the drive stopping means (44) is set in advance after the determining means (43) outputs a rising signal. If the output current I of the power conversion circuit (20) does not fall below the first set value I1 within the first lock determination time TM11, a stop signal is output to the drive circuit (31).

According to a third aspect of the present invention, in the first aspect of the present invention, the drive stopping means (44) comprises a power conversion circuit after the determination means (43) outputs a rising signal. The output current I of (20) is equal to the first set value I1 and the second set value I1.
A time for maintaining the high current state between the set value I2 and the accumulated time is integrated, and this integrated time is set to a predetermined second lock determination time.
When the signal reaches TM21, a stop signal is output to the drive circuit (31).

Further, the means adopted by the invention according to claim 4 is that, in the invention described in claim 1, the output current I of the power conversion circuit (20) detected by the current detection means (CT) is:
It is determined whether or not the output current I has exceeded the second set value I2 within a predetermined abnormality determination time. If the output current I has exceeded the second set value I2, the drive circuit (31) is provided separately from the drive stopping means (44). The configuration is provided with abnormal stop means (45) for outputting a stop signal.

The means adopted by the invention according to claim 5 is the electric motor (CM) according to the invention described in claim 1.
Is a motor of a compressor provided in the air conditioner.

-Operation- According to the above-mentioned invention specifying matter, in the invention of claim 1,
If the output current I of the power conversion circuit (20) detected by the current detection means (CT) does not rise above the first set value I1 when the motor (CM) is started, the motor is normally accelerated, and therefore, normally Driving will continue.

On the other hand, when the output current I of the power conversion circuit (20) exceeds the first set value I1 but does not reach the second set value I2, the determination means (43) outputs a rising signal. However, the drive stopping means (44) outputs a continuation signal. And although the load torque at startup was large,
Thereafter, when the output current I of the power conversion circuit (20) decreases and becomes lower than the first set value I1, the operation has shifted to the normal operation, and the normal operation is continued.

That is, the first set value I1 is a so-called rated current, and there is a margin before reaching the second set value I2 which causes destruction of the control element (Tr, Tr,. Since there is no problem in increasing the current I, the output current I is increased to increase the torque.

When the output current I of the power conversion circuit (20) exceeds the first set value I1 and reaches the second set value I2, the motor (CM) is locked, and the power conversion circuit ( The output of 20) is stopped, that is, the operation is stopped and a lock display or the like is performed.

According to the second aspect of the present invention, the output current I of the power conversion circuit (20) exceeds the first set value I1, but does not reach the second set value I2, but the first set value I1
If the current value does not decrease further, it is considered that an unexpected abnormality or a lock of the electric motor (CM) whose current value at the time of locking is set to a relatively small value has occurred. Therefore, since the stress of the motor (CM) can be tolerated as it is, when the drive stopping means (44) counts the lock determination time, the motor (C)
M) is determined to be overloaded according to the lock, and the power conversion circuit (2
The output of 0) is stopped, and a lock display or the like is performed.

Further, according to the third aspect of the present invention, the output current I of the power conversion circuit (20) fluctuates up and down near the first set value I1, and the first set value I1 and the second set value I2 are changed. If the integration time to maintain the high current state during the period becomes longer, the motor (CM) is considered to be locked, so the output of the power conversion circuit (20) is stopped, that is, the operation is stopped and the lock is displayed. And so on.

Further, in the invention according to the fourth aspect, the abnormality stopping means (45) sets the power conversion circuit (20) within the abnormality determination time.
When it is determined that the output current I has instantaneously reached the second set value I2, the control elements (Tr, T
(r,...) may be short-circuited or the like, so that the output of the power conversion circuit (20) is stopped to display an abnormality or the like.

[0024]

Therefore, according to the present invention, two reference values, a first set value I1 which is a protection upper limit value based on a time limit characteristic and a second set value I2 which is a protection upper limit value based on an instantaneous characteristic, are set. Then, when the output current I of the power conversion circuit (20) exceeds the second set value I2, the motor (CM) is determined to be locked and stopped, so that acceleration is stopped or deceleration is performed as in the related art. The output current I of the power conversion circuit (20) at the time of startup can be increased as compared with a method of performing the operation, and the compressor can be started stably even when a large load torque is required. .

Further, when the output current I of the power conversion circuit (20) reaches the second set value I2, the lock of the motor (CM) is determined, so that a predetermined protection function can be ensured.

According to the second aspect of the present invention, the motor (CM) is stopped when the output current I of the power conversion circuit (20) continues to exceed the first set value I1. It is possible to reliably prevent continuation of an overload operation in accordance with the lock of the motor, and to reliably prevent the motor (CM) having a low starting current from being locked.

According to the third aspect of the present invention, the lock of the motor (CM) is determined even when the output current I of the power conversion circuit (20) rises and falls near the first set value I1. Therefore, a predetermined protection function can be ensured.

According to the fourth aspect of the present invention, the output current I of the power conversion circuit (20) is instantaneously changed to the second set value I.
Since it stops when it reaches 2, the abnormality such as destruction of the control element (Tr, Tr,...) Of the power conversion circuit (20) can be determined, so that the cause of the stop can be reliably identified. it can.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 2, (10) is a control device for an induction motor (CM) of a compressor which is a compressor motor provided in an outdoor unit of the air conditioner, and includes a power conversion circuit (20). And a power control circuit (30), and supplies control power to the induction motor (CM) from a power supply (PS) via a power conversion circuit (20).

The power conversion circuit (20) converts three-phase AC power supplied from a power supply (PS) into controlled three-phase AC power, and includes a rectifier circuit (21) and a smoothing circuit (2).
2) and an inverter circuit (23). And
The rectifier circuit (21) includes six diodes (d1, d1,
…) And a power supply (P
A diode module connected to S) that performs full-wave rectification on AC from the power supply (PS).

The smoothing circuit (22) is for smoothing the full-wave rectified DC by the rectifier circuit (21), and is provided with a reactor (2L) and a capacitor circuit (2C) having a smoothing capacitor (2C). 2a) and a resistor circuit (2b) having a discharge resistor (2R) are connected to a power supply line (2P, 2P).
N). The smoothing circuit (22) includes a current detecting means (CT) such as a current transformer or a shunt resistor for detecting a DC section current, that is, an inverter output current I supplied to the induction motor (CM) by the inverter circuit (23). ) Are provided on the power supply line (2N).

The inverter circuit (23) includes a transistor having six power transistors (Tr, Tr,...).
A smoothing circuit (22) is a transistor module that converts a smoothed direct current into an alternating current, and is connected to an induction motor (CM) to supply three-phase AC control power to the induction motor (CM). I have. The power transistors (Tr, Tr,...) Are connected with a free-wheeling diode (d2, d2,...) Between the emitter and the collector, and the power transistors (Tr, Tr,. ) Is turned ON / OFF by the drive signal.

The power control circuit (30) receives a current signal from the current detection means (CT) while the drive circuit (31)
And a CPU (40). The drive circuit (31)
The power transistor (Tr, Tr,...) Modulates the DC voltage smoothed by the smoothing circuit (22) by PWM modulation (pulse width modulation).
A drive signal is output to the power transistor (Tr, Tr,...) So as to perform the operation. The CPU (40) is provided with an air conditioning load signal such as an indoor temperature, and is provided with speed control means (41) and optimum control means (42).

The speed control means (41) receives an air conditioning load signal such as an indoor temperature, and derives a supply frequency of an induction motor (CM) which is an operating frequency of the compressor in accordance with the air conditioning load signal. Then, a control signal is output to the drive circuit (31) so as to have the supply frequency.

That is, the speed control means (41) controls the drive of the inverter circuit (23) so that the supply frequency and the supply voltage of the induction motor (CM) change based on a preset reference voltage frequency characteristic. A control signal for controlling the supply frequency of the induction motor (CM) to control the induction motor (CM) at a variable speed is output to the drive circuit (31). Then, the drive circuit (31) outputs the drive signal to the inverter circuit (23) of the power conversion circuit (20) based on the control signal.

The optimal control means (42) drives an adjustment signal for adjusting the supply voltage so as to minimize the motor current by making the supply voltage of the induction motor (CM) minutely fluctuate by a predetermined fluctuation amount. Output to the circuit (31). Then, the drive circuit (31) outputs the drive signal to the inverter circuit (23) of the power conversion circuit (20) based on the adjustment signal.

As a feature of the present invention, the CPU (40) is provided with a discriminating means (43) and a drive stopping means (44), while the power control circuit (30) is provided with a power failure stopping means (45). ) Is provided.

When the induction motor (CM) is started, the discriminating means (43) determines whether the inverter output current I detected by the current detecting means (CT) is equal to the induction motor (CM) and the power conversion circuit (20).
It is determined whether or not the inverter output current I has exceeded the first set value I1 which is a protection upper limit value based on a time limit characteristic for protecting a power transistor (Tr, Tr,...) Which is a control element of the inverter. When the value exceeds the value I1, a rising signal is output.

The drive stopping means (44) is provided with a discriminating means (4
3) outputs a rising signal, outputs a driving continuation signal to the drive circuit (31), and outputs the inverter output current I within a preset first lock determination time TM11 from the output of the rising signal. The inverter determines whether the set value is higher than the first set value I1 and exceeds a second set value I2 which is a protection upper limit based on an instantaneous characteristic for protecting the power transistors (Tr, Tr,...). When the output current I exceeds the second set value I2, it is determined that the induction motor (CM) is locked, and a stop signal is output to the drive circuit (31).

If the inverter output current I does not drop below the first set value I1 within the first lock determination time TM11, the drive stop means (44) determines that the overload is equivalent to the lock and determines that the drive circuit (31) ) To output a stop signal.

Further, the drive stopping means (44) detects that the inverter output current I is in a high current state between the first set value I1 and the second set value I2 after the determination means (43) outputs the rising signal. When the accumulated time reaches a preset second lock determination time TM21, the driving circuit (31)
Output a stop signal.

The abnormal stopping means (45) determines whether or not the inverter output current I detected by the current detecting means (CT) has exceeded the second set value I2 within a predetermined abnormality determining time. When the output current I exceeds the second set value I2, a stop signal is output to the drive circuit (31) separately from the drive stop means (44). That is, since it is considered that the inverter output current I instantaneously increases due to an abnormality such as a short circuit of the power transistor (Tr, Tr,...), The output of the inverter circuit (23) is stopped.

-Control Operation of Induction Motor (CM)-Next, the control operation of the above-described induction motor (CM) will be described.

First, when an operation command such as a cooling operation is output from a remote controller (not shown) in a state where the power supply (PS) is turned on and the switching circuit (11) is turned on, the CPU (40) receives the operation command. Then, the speed control means (41) outputs a control signal. The control signal is received by the drive circuit (31), and the drive signal is output to the inverter circuit (23), and the power transistors (Tr, Tr,...) Are turned ON / OFF.

On the other hand, the three-phase AC power from the power supply (PS) is full-wave rectified by a rectifier circuit (21), converted into DC, smoothed by a smoothing circuit (22), and then converted by an inverter circuit (22). Output to 23). And six power transistors (Tr, Tr,...) Of the inverter circuit (23).
Converts a direct current into an alternating current and supplies a predetermined supply voltage to an induction motor (CM) by pulse width modulation.

The CPU (40) receives an air-conditioning load signal such as an indoor temperature, and the speed control means (41)
The supply frequency of the induction motor (CM), which is the operating frequency of the compressor, is derived in response to the air conditioning load signal, and a control signal is output to the drive circuit (31) so as to reach the supply frequency. That is, the speed control means (41) controls the drive of the inverter circuit (23) so that the supply frequency and the supply voltage of the induction motor (CM) change based on the preset reference voltage frequency characteristic. And the drive circuit (31) outputs a drive signal to the inverter circuit (23) based on the control signal. As a result, the induction motor (CM)
Will rotate in response to the air conditioning load.

When the induction motor (CM) is rotating, the optimum control means (42) makes the supply voltage of the induction motor (CM) minutely fluctuate by a predetermined fluctuation amount so that the motor current is minimized. And outputs an adjustment signal to the drive circuit (31). Then, the drive circuit (31) outputs a drive signal to the inverter circuit (23) based on the adjustment signal so that the induction motor (CM) rotates at the most efficient minimum current value.

-Start-up control operation- Next, the control operation at the time of start-up, which is a feature of the present invention, will be described based on the control flow of FIG.

First, when the control operation is started, step ST
In step 1, it is determined whether the inverter output current I detected by the current detection means (CT) has reached the second set value I2. If the inverter output current I has not reached the second set value I2, the process proceeds to step ST1.
Is negative, the process proceeds to step ST2, and the first timer
It is determined whether TM-1 and the second timer TM-2 are counting.

The first timer TM-1 starts counting when the inverter output current I reaches the first set value I1, and is reset when the inverter output current I falls below the first set value I1. On the other hand, the second timer TM-2 integrates the time when the inverter output current I has become equal to or greater than the first set value I1,
Even if the inverter output current I falls below the first set value I1, it is not reset. For example, when the inverter output current I rises and falls near the first set value I1, it becomes equal to or more than the first set value I1. This is a timer for counting the integration time.

In step ST2, the first timer TM
If -1 and the second timer TM-2 are not counting, the determination is no and the process moves to step ST3, where it is determined whether or not the engine is activated. If not, the determination is no and the process proceeds to step ST3.
Then, the process proceeds to step 4, where the first timer TM-1 and the second timer TM-2 are reset and the process returns, and the operation from step ST1 is performed. That is, the determination in step ST2 is performed to determine whether or not control is performed at the time of startup.

If it is determined in step ST3 that it is a start-up time, the determination is YES and the process moves to step ST5, where it is determined whether or not the inverter output current I has reached the first set value I1. I is the first set value I1
If not, the process proceeds to step ST6, where the first timer
TM-1 is reset, the routine returns with the second timer TM-2 kept in the current count state, and the operation from step ST1 is performed.

At the start of step ST3, the first
When the timer TM-1 and the second timer TM-2 are operating, the process proceeds from step ST2 to step ST5.
If the induction motor (CM) is normally driven after this startup and the inverter output current I does not rise above the first set value I1,
That is, as shown in FIG. 4A, when the vehicle is accelerated normally,
Normal operation is continued as it is.

On the other hand, if the inverter output current I has reached the first set value I1 in step ST5, the determination is YES and the process moves to step ST7, where the first timer TM-1 starts counting and , The integrating operation of the second timer TM-2 is started.

Thereafter, from the above-mentioned steps ST7 to ST
In step 8, it is determined whether the first timer TM-1 or the second timer TM-2 has counted a preset first lock determination time TM11 or first lock determination time TM21. Until the first lock determination time TM11 or the first lock determination time TM21, the determination in step ST8 is NO and the process returns, and the operation from step ST1 is performed.

Subsequently, when the first timer TM-1 and the second timer TM-2 are operating at the start of the step ST3, the process returns from the step ST8 to the step ST1 and the above-mentioned operation is repeated. However, there are cases where the inverter output current I exceeds the first set value I1, but does not reach the second set value I2. At this time, as shown in FIG. 4B, although the load torque at the time of startup was large, but the inverter output current I subsequently decreased to become lower than the first set value I1, normal operation was started. The process moves from ST5 to step ST6, and normal operation is continued.

That is, the first set value I1 is a so-called rated current, and there is a margin before the second set value I2 or more causing the destruction of the power transistors (Tr, Tr,...) Is reached. Since there is no problem in increasing the output current I, the inverter output current I is increased to increase the torque.

On the other hand, when the first timer TM-1 and the second timer TM-2 are operating at the start of the step ST3, the process returns from the step ST8 to the step ST1 and the above operation is repeated. When the inverter output current I exceeds the first set value I1 and reaches the second set value I2, the induction motor (CM) is locked as shown in FIG. 4C. Therefore, the determination in step ST1 becomes YES, and the process proceeds to step ST9, in which it is determined whether the first timer TM-1 or the second timer TM-2 has counted a predetermined abnormality determination time TM12, TM22. I do. And the first timer TM
If -1 or the second timer TM-2 has counted the abnormality determination times TM12 and TM22, the determination in step ST9 becomes YES, and the process proceeds to step ST10, where the lock of the induction motor (CM) is determined, and the inverter circuit is determined. The output of (23) is stopped, the first timer TM-1 and the second timer TM-2 are reset, and the routine returns. In other words, the operation is stopped and the lock is displayed.

When the first timer TM-1 and the second timer TM-2 are operating at the start of the step ST3, the process returns from the step ST8 to the step ST1 and the above operation is repeated. Although the inverter output current I exceeds the first set value I1 but does not reach the second set value I2, the inverter output current I may not drop below the first set value I1. That is, as shown in FIG. 4D, when the state where the inverter output current I continues to exceed the first set value I1 is continued,
It is considered that an unexpected abnormality has occurred.

Therefore, since the stress of the induction motor (CM) can be tolerated as it is, when the first timer TM-1 counts the first lock determination time TM11, the determination in step ST8 is YE.
In S, the process proceeds to step ST10, where it is determined that the overload is equivalent to the lock of the induction motor (CM), and the inverter circuit (23)
Is stopped, the first timer TM-1 and the second timer TM-2 are reset and the process returns, and the operation is stopped to display the lock or the like.

When the first timer TM-1 and the second timer TM-2 are operating at the start of the step ST3, the process returns from the step ST8 to the step ST1 and the above operation is repeated. In some cases, the inverter output current I fluctuates near the first set value I1 and does not reach the second set value I2. In this case, the second timer TM-2
When the inverter output current I is equal to the first set value I1 and the second set value I
Since the time during which the high current state is maintained between the second lock determination time TM2 and the second lock determination time TM21 is determined, the determination in step ST8 becomes YES, and the process proceeds to step ST8.
Move to ST10, determine that the induction motor (CM) is locked, stop the output of the inverter circuit (23), reset the first timer TM-1 and the second timer TM-2, return, and stop the operation Thus, the above lock is displayed.

On the other hand, when the first timer TM-1 and the second timer TM-2 are operating at the start of the step ST3, the process returns from the step ST8 to the step ST1 and the above-mentioned operation is repeated. When the inverter output current I exceeds the first set value I1 and instantaneously reaches the second set value I2, in the step ST9, the first timer TM
If -1 or the second timer TM-2 has not finished counting the abnormality determination times TM21 and TM22 or does not enter the count operation, the determination is NO and the process proceeds to step ST11, where the power transistors (Tr, Tr ,...), It is considered that the inverter output current I increased instantaneously due to an abnormality such as a short circuit.
Therefore, the output of the inverter circuit (23) is stopped, the first timer TM-1 and the second timer TM-2 are reset, and the routine returns. That is, the operation is stopped, and the display of the abnormality is performed.

-Effects of Embodiment- As described above, according to the present embodiment, the first set value I1 which is the protection upper limit value based on the time limit characteristic and the second set value I2 which is the protection upper limit value based on the instantaneous characteristic. When the inverter output current I exceeds the second set value I2, the lock of the induction motor (CM) is determined and stopped. Therefore, acceleration is stopped as in the prior art. The inverter output current I at the time of starting can be increased as compared with a method of decelerating or decelerating, and the compressor can be started stably even when a large load torque is required.

When the inverter output current I reaches the second set value I2, the lock of the induction motor (CM) is determined, so that a predetermined protection function can be ensured.

Further, since the inverter is stopped when the inverter output current I continues to exceed the first set value I1, it is ensured that the overload operation according to the lock of the induction motor (CM) is continued. And locking of the induction motor (CM) having a low starting current can be reliably prevented.

Even when the inverter output current I fluctuates near the first set value I1, the lock of the induction motor (CM) is determined, so that a predetermined protection function can be ensured.

In addition, when the inverter output current I instantaneously reaches the second set value I2, the operation is stopped.
Since abnormality such as destruction of the power transistor (Tr, Tr,...) Can be determined, the cause of the stop can be reliably identified.

[0069]

Other Embodiments In this embodiment, an induction motor (CM) of a compressor of an air conditioner has been described. However, in the inventions according to claims 1 to 3, various types of induction motors (CM) are used. It is applicable and the invention is not limited to induction motors (CM).

Although the inverter circuit (23) in this embodiment uses six power transistors (Tr, Tr,...), The present invention uses six IGBTs (Insulated Gate).
Bipolar Transistor) may be used.

The current detecting means (CT) may be provided between the power conversion circuit (20) and the induction motor (CM). In this case, the number of the current detecting means (CT) is one, Two or three
One of the two.

Further, according to the second aspect of the present invention, the first timer
TM-1 alone may be used.
Needless to say, only the timer TM-2 may be used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a control circuit diagram of the induction motor.

FIG. 3 is a flowchart showing start control.

FIG. 4 is a characteristic diagram of an inverter output current at the time of startup.

FIG. 5 is a characteristic diagram of an inverter output current at the time of conventional startup.

[Explanation of symbols]

 20 Power conversion circuit 21 Rectifier circuit 22 Smoothing circuit 23 Inverter circuit 30 Power control circuit 31 Drive circuit 40 CPU 43 Judgment means 44 Driving stop means 45 Abnormal stop means CT Current detection means

Claims (5)

[Claims] 1. A power conversion circuit (20) that includes a power supply (PS) and a motor (CM), converts power supplied from the power supply (PS) into predetermined control power, and outputs the control power to the motor (CM).
A drive circuit (31) for outputting a drive signal to the power conversion circuit (20); and a current detection means (CT) for detecting an output current I output from the power conversion circuit (20) to the electric motor (CM). When the motor (CM) is started, the output current I of the power conversion circuit (20) detected by the current detection means (CT) is changed by the motor (C).
M) and control elements (Tr, Tr, ...) of the power conversion circuit (20)
Is the upper limit of protection based on the time limit characteristic for protecting
It is determined whether or not the output current I has exceeded the first set value I1. The determination means (43) outputs a rising signal when the output current I exceeds the first setting value I1, and the determination means (43) outputs a rising signal. A drive continuation signal is output to the drive circuit (31), and the output current I of the power conversion circuit (20) is a set value higher than the first set value I1 and the control of the power conversion circuit (20) is performed. It is determined whether or not the output current I exceeds a second set value I2 which is a protection upper limit value based on an instantaneous characteristic for protecting the elements (Tr, Tr,...). Circuit (3
(1) An electric motor start-up control device, comprising: a driving stop means (44) for outputting a stop signal. 2. The start control device for an electric motor according to claim 1, wherein the drive stop means (44) is configured to set the first lock determination time TM11 within a predetermined first lock determination time TM11 after the determination means (43) outputs the rising signal. An activation control device for an electric motor, which outputs a stop signal to a drive circuit (31) when an output current I of a power conversion circuit (20) does not fall below a first set value I1. 3. The start control device for an electric motor according to claim 1, wherein the drive stopping means (44) determines that the output current I of the power conversion circuit (20) is less than the output current I after the determination means (43) outputs the rising signal. A time for maintaining the high current state between the first set value I1 and the second set value I2 is integrated, and when the integrated time reaches a second lock determination time TM21 set in advance, a stop signal is sent to the drive circuit (31). And a motor start-up control device. 4. The motor start control device according to claim 1, wherein the output current I of the power conversion circuit (20) detected by the current detection means (CT) is set to a second set value I2 within a predetermined abnormality determination time. It is determined whether or not the output current I has exceeded the second set value I2.
Exceeds the drive stop means (44) and the drive circuit (3
(1) An electric motor start-up control device, comprising: an abnormal stop means (45) for outputting a stop signal. 5. The start control device for an electric motor according to claim 1, wherein the motor (CM) is a motor of a compressor provided in the air conditioner.