JP5339985B2 - Inverter controller for DC motor drive - Google Patents

Description

  The present invention relates to an inverter control device for driving a DC motor that drives a DC motor connected to an inverter, and relates to an apparatus for stably operating a DC motor with a maximum capacity.

  In general, an inverter control device that drives a compressor for an air conditioner does not exceed the current capacity (for example, 15 A) of the power breaker in an air conditioner that is supplied with commercial AC power through an indoor wiring breaker. Control the compressor. For example, primary current detection means is provided on the input side of the breaker, the value of the current (primary current) of the commercial AC power supply 1 is detected by the primary current detection means, and the information is detected by a microcomputer (the main part of the inverter control device) Yes, hereinafter referred to as a microcomputer). Inside the microcomputer, the operating frequency calculation unit determines the frequency so that the value of the primary current taken in does not exceed the current regulation value stored in advance in the current limit value storage unit. The waveform generation unit outputs a drive signal matched with the frequency determined by the operation frequency calculation unit to the inverter unit, and the compressor operates by applying a desired waveform from the inverter unit to the compressor. At this time, by setting the current regulation value stored in the current limit value storage unit to a value smaller than the current capacity of the power breaker (for example, 14A), the maximum capacity operation of the air conditioner is prevented while preventing the operation of the power breaker. Is realized. As a specific example of a control device that restricts the operating current to be equal to or less than the current capacity of the power breaker, for example, a method disclosed in Patent Document 1 is known.

JP-A-4-106348 (first page to third page, FIGS. 1 and 2) Japanese Patent No. 3680016

  The conventional inverter device for an air conditioner is configured as described above, and is configured to operate the compressor while limiting the current to be equal to or less than the current capacity of the power breaker. Conventionally, the operating limit of the compressor is higher than the current capacity of the power breaker, so that no problem has occurred in the system even if only the restriction on the current capacity of the power breaker is implemented. On the other hand, in recent air conditioners, DC motors are the mainstream as motors for compressors due to demands for higher efficiency, and as a method for further improving the efficiency, the DC motor is strengthened by increasing the magnetic force. A method of reducing is used. In general, when the magnetic force of the DC motor is increased, the limit value for the step-out of the DC motor is reduced (that is, the step-out becomes easy). For this reason, there is a possibility that a reverse phenomenon occurs in which the operating limit of the compressor becomes lower with respect to the current capacity of the power breaker. In the conventional method of limiting the current value only to the power breaker, the motor is disconnected. As a result, the air conditioner system may stop.

  In the current limiting method for the current capacity of the power supply breaker, when the power supply voltage fluctuates, the input value of the inverter control device fluctuates accordingly. As a result, the input value increases when the power supply voltage is high. Therefore, when the power supply voltage is high, heat generation of the switching element of the inverter device increases, and there are problems such as protection stop due to temperature and destruction of the switching element.

  Furthermore, when operating a DC motor with an unknown step-out limit value under the maximum load condition, it is not possible to prevent the DC motor from stepping out only by limiting the current to the power breaker. There was a risk of stopping. Also, when there are many types of DC motors for compressors, the step-out limit value differs for each motor, so it is necessary to set separate current limit values for all the motors, which is very complicated. If the setting is changed or simplified, the current regulation value has a large margin with respect to the DC motor step-out limit, and there is a problem that the performance of the DC motor cannot be fully exhibited. It was.

The present invention has been made to solve the above-described problems, and is capable of operating at maximum capacity in a stable state without being affected by the specifications of the DC motor while preventing the operation of the power breaker. An object is to obtain an inverter control device for driving an electric motor.
In addition, even when the power supply voltage fluctuates, the DC motor drive inverter control device that can operate at maximum capacity in a stable state without being stopped due to unnecessary step-out of the DC motor or protection due to excessive heat generation of the switching element The purpose is to obtain.

An inverter control device for driving a DC motor according to the present invention includes a converter unit that converts electric power of a commercial AC power source into DC power, and an inverter unit that converts DC power from the converter unit into AC power and supplies the AC power to the DC motor. And an inverter control unit that controls the inverter unit, a current detection unit that detects a current of the commercial AC power supply, and a step-out state of the DC motor is extremely compared with a cycle corresponding to the operating frequency of the DC motor. A step-out state detecting means for repeatedly monitoring and detecting in a short cycle , wherein the inverter control unit stores a current limit value of the commercial AC power source as a primary current limit value, and the step-out state An operation limit current value calculating means for calculating a limit current value at which the DC motor can normally operate based on the output of the detection means and the output of the current detection means; A current limit value calculation unit that compares the primary current limit value stored in the storage means with the output of the operation limit current value calculation means and outputs the lower current value as the current limit value of the current supplied to the DC motor. An operation frequency calculation unit that determines an operation frequency so as to be an output of the current limit value calculation unit, and a waveform generation unit that outputs a drive signal that matches the output of the operation frequency calculation unit to the inverter unit, It is provided.

  According to the present invention, the maximum capacity operation can always be performed in a stable state without being affected by the specifications of the DC motor while preventing the operation of the power breaker, and the DC motor can be removed unnecessarily even when the power supply voltage fluctuates. Because it is possible to operate in a stable state without entering into a stop due to adjustment or protection due to excessive heat generation of the switching element, it is possible to improve reliability while maximizing the performance of a system using a DC motor Has an effect.

It is a schematic diagram showing the structure of the inverter control apparatus for DC motor drive in Embodiment 1 of this invention. It is a schematic diagram showing the structure of the inverter control apparatus for DC motor drive in Embodiment 2 of this invention. It is a schematic diagram showing the structure of the inverter control apparatus for DC motor drive in Embodiment 3 of this invention. It is a schematic diagram showing the structure of the inverter control apparatus for DC motor drive in Embodiment 4 of this invention. It is a conceptual diagram which shows the relationship between the number of step-out in Embodiment 7 of this invention, and a limiting current calculation coefficient. It is a flowchart which shows the flow of the process in Embodiment 1 of this invention. It is a flowchart which shows the flow of the process in Embodiment 2 of this invention. It is a flowchart which shows the flow of the process in Embodiment 3 of this invention. It is a flowchart which shows the flow of the process in Embodiment 4 of this invention. It is a flowchart which shows the flow of the process in Embodiment 7 of this invention. It is a flowchart which shows the flow of the process at the time of a step-out in this invention.

Embodiment 1 FIG.
Hereinafter, the form of an inverter control device for driving a DC motor according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an inverter control device for driving a DC motor according to Embodiment 1 of the present invention.

  As shown in FIG. 1, an inverter control device for driving a DC motor includes a converter unit 5 that converts AC power of a commercial AC power source 1 into DC power, and converts DC power from the converter unit 5 into AC power. An inverter unit 6 to be supplied to the DC motor 7, a microcomputer (inverter control unit, hereinafter referred to as a microcomputer) 8 for controlling the inverter unit 6, and a primary current detecting means 9 for detecting the current of the commercial AC power source 1; The step-out state detecting means 17 for detecting the step-out state of the DC motor 7 is constituted. The converter unit 5 includes a reactor 2, a rectifying diode bridge 3, and a smoothing electrolytic capacitor 4. The inverter unit 6 includes a switching element (not shown) that converts the DC voltage generated by the converter unit 5 into three-phase AC by performing on / off control with a drive signal from the microcomputer 8. The DC motor 7 is connected to the inverter unit 6 and can be operated at an arbitrary number of revolutions by controlling the voltage supplied from the inverter unit 6.

  The microcomputer 8 includes a current limit value storage unit 11 that stores a regulation value of the primary current, and a limit current value (hereinafter, an operation limit current) at which the DC motor 7 can be normally operated from the step-out state detection unit 17 of the DC motor 7. An operation limit current value calculation unit 15 for calculating the control value of the primary current detected by the primary current detecting means 9 and comparing the operation limit current value with the lower limit current value. Control as.

The step-out state detecting means 17 for detecting the step-out state of the DC motor 7 is a step-out step for determining whether or not there is a step-out by processing the detected current in the microcomputer and the motor current detecting unit 10 for detecting the current of the DC motor. The determination unit 16 is configured. Although various methods are disclosed as a method for detecting the step-out state of the DC motor, there is Patent Document 2 as a representative method.
Patent Document 2 discloses a method of determining a normal operation state and a step-out state by detecting a current of a DC motor and processing the current information inside the microcomputer. Specifically, the current of the DC motor is detected, the detected current is coordinate-converted into an excitation current component (d-axis current) and a torque current component (q-axis current), and an AC component of this dq-axis current is extracted. Then, when any of the dq-axis current alternating current components exceeds a preset step-out determination value, it is determined that step-out has occurred. For example, when the q-axis current alternating current component is used for the step-out detection signal, the absolute value of the q-axis current alternating current component is calculated, and when the predetermined step-out determination value is exceeded, it is determined that the step-out occurs.

  As described above, in Patent Document 2, a step-out determination value is determined by providing a step-out determination value. However, in the present invention, a level lower than the step-out determination value using the same circuit configuration and detection method. By providing another determination value (operation limit determination value), it becomes possible to detect the state immediately before the step-out. In addition, by incorporating the information of the operation limit determination value into the control, the DC motor can be operated with the limit current without falling into a stop state due to step-out.

FIG. 6 is a flowchart showing a flow of processing for determining a current limit value of the inverter control device for driving a DC motor according to Embodiment 1 of the present invention.
Next, the operation of the first embodiment will be described with reference to FIGS.

The process starts at ST1 in FIG. In ST2, the operation limit current value calculation unit 15 compares the step-out detection signal with the operation limit determination value, and if the step-out determination signal exceeds the operation limit determination value, the compressor has generated a step-out abnormality. Proceed to Note that “the step-out determination signal has exceeded the operation limit determination value” means that the operation limit current value calculation unit 15 sets the step-out determination signal from the step-out determination unit 16 and the preset operation limit determination value of the compressor. Therefore, it means that a slight step-out of the DC motor has been detected because the monitoring is repeatedly performed with an extremely short period.
In ST3, the operation limit current value calculation unit 15 sets the detected value of the primary current at that time (when the step-out is detected) as the operation limit current value, and proceeds to ST5. Since the detected value of the primary current is the primary current value at the time when the slight step-out is detected as described above, it indicates the maximum current value that can be substantially operated. This means that the maximum operable current value is set as the operation limit current value. In ST5, the current limit value calculation unit 12 compares the operation limit current value with the primary current regulation value, and branches to the processes of ST6 and ST7 according to the comparison result.
ST6 and ST7 are processes for determining the smaller current value of the comparison result in ST5 as the current limit value. That is, when the primary current regulation value is smaller than the operation limit current value, the current limit value calculation unit 12 sets the primary current regulation value to the current limit value in ST6, and the operation limit current value is greater than the primary current regulation value. Is smaller, the operation limit current value is set to the current limit value in ST7.
In ST2, if the step-out detection signal is smaller than the operation limit determination value, the current limit value calculation unit 12 is executing a normal operation without step-out, so the operation limit current value is set to 20A in ST4. To do. The meaning of 20A is set to a value larger than the primary current regulation value (for example, 20A for a breaker model with a current capacity of 15A), so that the primary current regulation value is always limited in the next step (ST5). It is a value for making a value.

  In FIG. 1, the operation limit current value calculation unit 15 determines the operation limit current value by the processing described in ST2 to ST4 in FIG. The current limit value calculation unit 12 calculates a final current limit value by the processing described in ST5 to ST7 in FIG. The operating frequency calculator 13 determines the operating frequency so as to be the current limit value. The waveform generation unit 14 outputs a drive signal matched with the frequency determined by the operation frequency calculation unit 13 to the inverter unit 6 and operates the DC motor 7 by applying a desired waveform to the DC motor 7.

  As described above, the direct current motor is operated with the smaller current value as the current limit value among the primary current regulation value for preventing the operation of the power breaker and the operation limit current value that can be operated without stepping out the direct current motor. Can do.

  Thereby, the operation at the operation limit of the DC motor can be realized while always preventing the operation of the power breaker.

Embodiment 2. FIG.
In the first embodiment, when the power supply voltage fluctuates, it may be necessary to protect the switching element due to excessive heat generation by a high voltage. Therefore, in the second embodiment, a method for preventing such a situation from occurring will be described.

FIG. 2 is a schematic diagram showing the configuration of an inverter control device for driving a DC motor in Embodiment 2 of the present invention.
2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. Except for the primary voltage detection means 18 and the primary current limit value correction unit 19, the configuration is the same as in FIG. 1, so only the different parts will be described. The primary voltage detection means 18 detects the voltage (primary voltage) of the commercial AC power supply. The primary current limit value correction unit 19 corrects the primary current regulation value stored in the current limit value storage unit 11 using the primary voltage detected by the primary voltage detection unit 18. The primary voltage detection means 18 and the primary current limit value correction unit 19 are realized by the microcomputer 8.

  FIG. 7 is a flowchart showing the flow of the primary current regulation value correction process by the microcomputer 8. Next, the correction process of the primary current regulation value by the microcomputer 8 in the second embodiment will be described with reference to the flowchart of FIG. In FIG. 7, the same step numbers as those in FIG. 6 indicate the same processing contents. The processing from ST1 to ST4 in FIG. 7 is the same as that in FIG. After the processing of ST3 and ST4 is completed, the process proceeds to ST9. In ST9, the primary voltage detection means 18 detects the primary voltage (Vin). In ST10, the primary current limit value correcting unit 19 calculates the ratio of the primary voltage detected by the primary voltage detecting means 18 and the rated voltage (Vs) and determines the voltage ratio (voltage ratio = Vin / Vs). In ST11, the primary current limit value correction unit 19 determines whether the voltage ratio is larger than 1.0. If the voltage ratio is larger than 1.0, in ST12, the primary current regulation value is converted into the reciprocal of the voltage ratio (1 / voltage ratio). To correct the primary current regulation value. When the voltage ratio is 1.0 or less, the primary current limit value correction unit 19 does not correct the primary current regulation value in ST13, and keeps the value as it is. If the primary voltage is lower than the rated voltage by the processing from ST9 to ST13, the primary current regulation value is left as it is without correction so as to maintain the primary voltage value, and the primary voltage is higher than the rated voltage. In this case, the primary current regulation value is corrected according to the ratio between the rated voltage and the primary voltage so that the primary voltage becomes the rated voltage. The processing from ST5 to ST8 in FIG. 7 is the same as that in FIG.

  For example, in the case of a DC motor having a rated voltage of 100 V and a primary current regulation value of 15 A, the maximum input of the inverter device is 100 V × 15 A = 1500 W (when the power factor is 1). When the primary voltage is 90V, 90V × 15A = 1350W, and when the primary voltage is 110V, 110V × 15A = 1650W. As described above, when the primary current regulation value is constant, the maximum input varies depending on the primary voltage. That is, if the primary current regulation value is not corrected when the primary voltage is higher than the rated voltage, the load on the inverter increases and the heat generation of the switching element increases.

  On the other hand, the case where the primary current regulation value is corrected according to the ratio between the rated voltage and the primary voltage when the primary voltage according to the present invention is higher than the rated voltage will be described. When the primary voltage is 110V, the voltage ratio is 110V / 100V = 1.1, and the primary current regulation correction value = 15A × (1 / 1.1) = 13.64A. The maximum input value is 110V × 13.64A = 1500W, and even if the primary voltage fluctuates, the input becomes constant and the load on the inverter does not fluctuate. Therefore, even when the power supply voltage is high, the heat generated by the switching element of the inverter device does not increase.

  This realizes operation at the operating limit of the DC motor while preventing the operation of the power breaker, and even when the power supply voltage fluctuates, operation in a stable state without entering protection due to excessive heat generation of the switching element. realizable.

Embodiment 3 FIG.
The above embodiment has been described on the assumption that the step-out limit value is known in advance. In the third embodiment, a mode in which the number of step-outs is minimized when a DC motor with an unknown step-out limit value is operated under the maximum load condition will be described.

  FIG. 3 is a schematic diagram showing the configuration of an inverter control device for driving a DC motor according to Embodiment 3 of the present invention. 3 except for the step-out current storage unit 20, the configuration is the same as that in FIG. The step-out current storage unit 20 stores the value of the primary current when the step-out state detecting means 17 detects the step-out, and is realized by the microcomputer 8.

  FIG. 11 is a flowchart showing a flow of processing at the time of step-out by the microcomputer 8. Next, processing at the time of step-out by the microcomputer 8 in the third embodiment will be described with reference to the flowchart of FIG.

  In step ST101, a step-out determination process is started. In ST102, the step-out determination unit 16 converts the motor current detected by the motor current detection unit 10 into a step-out detection signal, compares the step-out detection signal with a preset step-out determination value, and detects the step-out detection signal. If exceeds the step-out determination value, the process proceeds to ST103. In ST103, the value of the primary current at the time of step-out is stored in the step-out current storage unit 20, and in step ST104, the step-out count is incremented (+1). When the step-out detection signal does not exceed the step-out determination value, the processes of ST103 and ST104 are not executed, and the step-out determination process is terminated at ST105. Thus, only when it is determined that the step-out has occurred, the primary current value at the time of the step-out is stored, and the number of steps out is counted. Note that the step-out determination unit 16 also stores the step-out count in the step-out current storage unit 20.

  As described above, the primary current at the time of step-out and the number of step-outs are stored.

  FIG. 8 is a flowchart showing the flow of limit operation processing by the microcomputer 8 when the step-out limit value of the DC motor is unknown in the third embodiment. Next, the correction process of the primary current regulation value when the step-out limit value by the microcomputer 8 in the third embodiment is unknown will be described with reference to the flowchart of FIG. In FIG. 8, the same step numbers as those in FIG. 6 indicate the same processing contents.

  The process starts in ST1 of FIG. In ST14, the operation limit current value calculation unit 15 checks the value of the step-out count. If the step-out count = 0, the process proceeds to ST4. If the step-out count is 1 or more, the process proceeds to ST15. In ST4, the operation limit current value calculation unit 15 sets the operation limit current to 20 A, and proceeds to ST5. In ST15, the operation limit current value calculation unit 15 calculates the operation limit current value (operation limit current = primary current at step-out × limit current calculation coefficient). For example, when the primary current at the time of step-out is 10 A and the limit current calculation coefficient is 0.8, the operation limit current value = 10 A × 0.8 = 8 A. After this, the process proceeds to ST5. The processing from ST5 to ST8 in FIG. 8 is the same as that in FIG.

  As described above, since the operation limit current of the DC motor is determined using information on the primary current at the time of step-out, limit operation is possible even when the step-out limit value of the DC motor is unknown.

  As a result, even when operating a DC motor with an unknown step-out limit value under the maximum load condition, always operate at the limit current value of the DC motor with the minimum number of step-outs while preventing the operation of the power breaker. Is possible.

Embodiment 4 FIG.
In the third embodiment, when the power supply voltage fluctuates, it may be necessary to protect the switching element due to excessive heat generation by a high voltage. Therefore, in the fourth embodiment, a method for preventing the occurrence of such a situation while satisfying the conditions of the third embodiment will be described.
FIG. 11 is also used in the fourth embodiment, but the description is omitted to avoid duplication of explanation.

  FIG. 4 is a schematic diagram showing the configuration of an inverter control device for driving a DC motor according to Embodiment 4 of the present invention. In FIG. 4, since the configuration other than the step-out current storage unit 20 is the same as that in FIG. 2, only different parts will be described. The step-out current storage unit 20 stores the value of the primary current when the step-out state detecting means 17 detects the step-out, and is realized by the microcomputer 8. The operation of the step-out current storage unit 20 is the same as that described in FIG.

  Fig. 9 shows that the limit value of the DC motor step-out is unknown, and the limit operation of the DC motor is performed stably even if the power supply voltage fluctuates by performing limit operation using the primary current value when the DC motor steps out. It is a flowchart which shows the flow of the process in the case of performing a driving | operation.

  In FIG. 9, the operation of ST1 to ST15 is the same as that of FIG. Further, the operations of the next ST9 to ST13 are the same as those of FIG. Further, the operations of the next ST5 to ST8 are the same as those of FIG.

  As an effect obtained as a result of executing the processing of FIG. 9, the effects of FIG. 8 and FIG. 7 are combined. Specifically, after determining the operating limit current of the DC motor using the primary current information at the time of step-out, the maximum input value of the inverter device increases as the power supply voltage increases, It can be prevented that the maximum input value of the inverter device becomes excessive from the adjustment limit value and the DC motor is again in a step-out state.

  As a result, even when a DC motor with an unknown step-out limit value is operated under the maximum load condition, the DC motor can be stably operated even when the power supply voltage fluctuates while always preventing the operation of the power breaker, and Limit operation can be realized with the minimum number of steps-out.

Embodiment 5 FIG.
In the fifth embodiment, a description will be given of a mode in which the primary current regulation value is not corrected when the primary voltage detection value is equal to or lower than the rated voltage.
The processing of ST9 to ST13 described in the flowchart of FIG. 7 or FIG. 9 represents the contents according to the present invention.

  In ST9, the primary voltage is detected by the primary voltage detection means, and the ratio between the primary voltage detected in ST10 and the rated voltage is calculated to determine the voltage ratio. If the voltage ratio is 1.0 or less in ST11, the primary current regulation value is not corrected in ST13 and is used as it is. That is, when the primary voltage detection value is equal to or lower than the rated voltage, the primary current regulation value is not corrected.

  For example, it is assumed that an inverter device having a primary current regulation value of 14.5 A is connected to a power source having a rated voltage of 100 V and a current capacity of 15 A of a power breaker. When the primary current regulation value is corrected in accordance with the voltage ratio when the primary voltage is 90 V, the voltage ratio = 90 V / 100 V = 0.9, and the primary current regulation correction value = 14.5 A × (1/0 .9) = 16.1A. Since the primary current regulation value exceeds the current capacity 15A of the power breaker, the power breaker may be activated. In order to prevent the operation of the power breaker, it is necessary to lower the primary current regulation value to a value that does not exceed the current capacity of the power breaker even if correction is made, in which case the power supply performance should be fully utilized. Can not be.

  As in the fifth embodiment, if the primary current regulation value is not corrected when the primary voltage detection value is less than or equal to the rated voltage, the primary current regulation value is set to the limit of the power breaker capacity. However, the operation of the power breaker can always be prevented.

Embodiment 6 FIG.
In the sixth embodiment, another mode for further minimizing the number of steps-out will be described.
Next, a sixth embodiment will be described. The processing of ST15 described in the flowchart of FIG. 8 or FIG. 9 represents the contents according to the present invention.

  When the step-out count is 1 or more at ST14, the operation limit current value is calculated at ST15 (operation limit current = primary current at step-out × limit current calculation coefficient). At this time, if the limit current calculation coefficient is set to 1 or more, the step-out state may occur again. In order to surely prevent the step-out state, the limit current calculation coefficient needs to be less than 1, and the limit current calculation coefficient may be changed by a DC motor. For example, by switching to a limit current calculation coefficient of about 0.9 in the case of a DC motor whose step-out limit value is known, and to about 0.8 in the case of a DC motor whose step-out limit value is unknown. Step-out can be reliably prevented while performing limit operation. As a matter of course, the closer the limit current calculation coefficient is to 1, the closer to the limit of the DC motor can be operated.

Embodiment 7 FIG.
In the seventh embodiment, another mode for further minimizing the number of steps-out will be described.
Next, a seventh embodiment will be described. The contents of the invention according to the present invention are described in FIG. 10 and FIG.

  The flowchart of FIG. 10 is obtained by adding the process of ST16 to the flowchart of FIG. 9, and the other processes are the same as those of FIG. In the process of ST16, the DC motor is operated at the limit of the step-out limit by gradually decreasing the limit current value calculation coefficient every time the step-out occurs.

  In ST16, if the step-out count = 1 (the number of step-out times) and the current limit resolution = 0.1, the limit current calculation coefficient = 1− (0.1 × 1) = 0.9. If further step-out occurs due to the rotational speed of the DC motor or other conditions, the step-out count = 2 (the number of step-out times is 2), and the limit current calculation coefficient = 1− (0.1 × 2) = 0.8. Become. If the step-out does not occur in this state, the limit current calculation coefficient is set to 0.8, and the process from ST9 is executed.

  FIG. 5 shows the relationship between the number of step-outs and the limiting current calculation coefficient, which is a feature of the present invention. As shown in FIG. 5, the limit current calculation coefficient gradually decreases as the number of step-outs increases, and the operation at the limit of the step-out limit becomes possible as the current limit resolution decreases. However, it should be noted that if the current limit resolution is reduced, the number of step-out steps increases until stable operation is possible.

  When the inventions of Embodiments 1 to 4 are mounted on an inverter for an air conditioner, the primary current limit value is set to be equal to or less than the current value defined for each product. As a result, even when the air conditioner and other devices are used together in the same power supply system, the operation of the power breaker can be prevented if the air conditioner is accurately selected based on the current value of the product. Of course, the limit value of the primary current of the air conditioner may be switched.

  In addition, in the inverter control apparatus for driving a DC motor shown in FIGS. 1 to 4, the motor current detection unit of the step-out state detecting means is described by a method for detecting the phase current of the DC motor. You may detect from an electric current. Also, when detecting the phase current, the current for two phases may be detected, or the current for three phases may be detected.

  The step-out state detecting means described this time detects step-out from the current of the DC motor. Of course, the step-out state may be detected by other methods.

  In the inverter control apparatus for driving a DC motor shown in FIGS. 1 to 4, the converter unit is described in a passive circuit system, but the converter unit may of course include an active converter system capable of controlling a DC voltage. Has the same effect.

  In the relationship between the number of step-outs and the limit current calculation coefficient described in FIG. 5, the limit current calculation coefficient at the first step-out is set to 1, but the limit current calculation coefficient at the first step-out is other than 1 (for example, 0.9), or the current limit resolution may be reduced by making the initial value other than 1.

  DESCRIPTION OF SYMBOLS 1 Commercial AC power supply, 2 Reactor, 3 Rectification diode bridge, 4 Smoothing electrolytic capacitor, 5 Converter part, 6 Inverter part, 7 DC motor, 8 Microcomputer, 9 Primary current detection means, 10 Motor current detection part, DESCRIPTION OF SYMBOLS 11 Current limit value memory | storage part, 12 Current limit value calculation part, 13 Operation frequency calculation part, 14 Waveform generation part, 15 Operation limit electric current value calculation part, 16 Step out determination part, 17 Step out state detection means, 18 Primary voltage Detection means, 19 primary current limit value correction unit, 20 step-out current storage unit.

Claims (8)

A converter unit that converts the power of the commercial AC power source into DC power, an inverter unit that converts DC power from the converter unit into AC power and supplies the DC power to the DC motor, an inverter control unit that controls the inverter unit, Current detection means for detecting the current of the commercial AC power supply, and step-out state detection means for repeatedly monitoring and detecting the step-out state of the DC motor in a very short period compared to the period corresponding to the operating frequency of the DC motor And comprising
The inverter control unit is configured to store the current limit value of the commercial AC power source as a primary current limit value, and based on the output of the step-out state detection means and the output of the current detection means, the DC motor An operation limit current value calculation unit that calculates a limit current value that can be normally operated, and a primary current limit value stored in the storage unit and an output of the operation limit current value calculation unit are compared, and a lower current value is calculated. A current limit value calculation unit that outputs as a current limit value of the current supplied to the DC motor, an operation frequency calculation unit that determines an operation frequency so as to be an output of the current limit value calculation unit, and an output of the operation frequency calculation unit And a waveform generation unit that outputs a drive signal matched to the inverter unit to the inverter unit. A converter unit that converts the power of the commercial AC power source into DC power, an inverter unit that converts DC power from the converter unit into AC power and supplies the DC power to the DC motor, an inverter control unit that controls the inverter unit, Current detection means for detecting the current of the commercial AC power supply, and step-out state detection means for repeatedly monitoring and detecting the step-out state of the DC motor in a very short period compared to the period corresponding to the operating frequency of the DC motor And comprising
The inverter control unit is configured to store the current limit value of the commercial AC power source as a primary current limit value, and based on the output of the step-out state detection means and the output of the current detection means, the DC motor An operation limit current value calculation unit that calculates a limit current value that can be normally operated, a voltage detection unit that detects a voltage of the commercial AC power supply, and the primary current according to a ratio of an output of the voltage detection unit and a rated voltage Primary current limit value correcting means for correcting the limit value, and comparing the output of the primary current limit value correcting means with the output of the operation limit current value calculating means, and comparing the output of the lower current value to the DC motor. A current limit value calculation unit that outputs as a current limit value of the current to be supplied, an operation frequency calculation unit that determines an operation frequency so as to be an output of this current limit value calculation unit, and an output of this operation frequency calculation unit A waveform generating section for outputting a driving signal to the inverter unit, the inverter control device for a DC motor drive, characterized in that it comprises a. A converter unit that converts the power of the commercial AC power source into DC power, an inverter unit that converts DC power from the converter unit into AC power and supplies the DC power to the DC motor, an inverter control unit that controls the inverter unit, Current detection means for detecting the current of the commercial AC power supply, and step-out state detection means for repeatedly monitoring and detecting the step-out state of the DC motor in a very short period compared to the period corresponding to the operating frequency of the DC motor And comprising
The inverter control unit stores a current limit value of the commercial AC power source as a primary current limit value, and a second storage unit stores a current value when the DC motor has stepped out. An operation limit current value calculating means for calculating, as the operation limit current value, a value obtained by multiplying the current value at the time of step-out stored in the second storage means by a fixed ratio, and the first storage means A current limit value calculation unit that compares the stored primary current limit value and the output of the operation limit current value calculation means and outputs the lower current value as the current limit value of the current supplied to the DC motor; An operation frequency calculation unit that determines an operation frequency so as to be an output of the limit value calculation unit, and a waveform generation unit that outputs a drive signal that matches the output of the operation frequency calculation unit to the inverter unit. Characteristic DC motor drive The inverter control device for use. A converter unit that converts the power of the commercial AC power source into DC power, an inverter unit that converts DC power from the converter unit into AC power and supplies the DC power to the DC motor, an inverter control unit that controls the inverter unit, Current detection means for detecting the current of the commercial AC power supply, and step-out state detection means for repeatedly monitoring and detecting the step-out state of the DC motor in a very short period compared to the period corresponding to the operating frequency of the DC motor And comprising
The inverter control unit includes a first storage unit that stores a current limit value of the commercial AC power source as a primary current limit value, a voltage detection unit that detects a voltage of the commercial AC power source, and an output of the voltage detection unit. Primary current limit value correction means for correcting the primary current limit value according to the ratio of the rated voltage, second storage means for storing the current value when the DC motor has stepped out, and the second storage means. Operating limit current value calculating means for calculating, as an operating limit current value, a value obtained by multiplying the current value at the time of step-out stored in the storage means by a certain ratio, and the output of the primary current limit value correcting means And an output of the current limit value calculation unit that outputs the lower current value as a current limit value of the current supplied to the DC motor, and the output of the current limit value calculation unit So as to determine the operating frequency And the wave number calculation unit, and a waveform generating section for outputting a driving signal according to the output of the operating frequency calculator to the inverter unit, the inverter control device for a DC motor drive, characterized in that it comprises a.   5. The DC motor drive unit according to claim 2, wherein the inverter control unit does not correct the primary current limit value when an output of the voltage detection unit is lower than a rated voltage. 6. Inverter control device.   5. The inverter control device for driving a DC motor according to claim 3, wherein the inverter control unit sets a ratio to be multiplied when calculating an operation limit current value at the time of step-out to less than 1. 5.   5. The DC motor driving device according to claim 3, wherein the inverter control unit gradually decreases a ratio to be multiplied when calculating an operation limit current value at the time of step-out from 1 every time step-out occurs. Inverter control device.   5. The inverter control apparatus for driving a DC motor according to claim 1, wherein the inverter control unit sets the limit value of the primary current to be equal to or less than a current value defined by a product. .

Images