JP3382018B2 - Inverter device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device used for speed control of an induction motor, and more particularly to an inverter device for automatically adjusting the acceleration / deceleration time of the induction motor.

[0002]

2. Description of the Related Art FIG. 9 is a block diagram of a conventional inverter device. In the figure, 1 is a converter section for converting an AC voltage into a DC voltage, 2 is a capacitor for smoothing the voltage converted by the converter section, 3 is a bridge-connected transistor and a diode, and is smoothed by a smoothing capacitor 2. The inverter unit 4 for reconverting the DC voltage into the AC voltage is connected to the induction motor 11 from the inverter unit.
A current detector for detecting a current supplied to the inverter, a control unit 20 for generating a signal for driving the inverter unit, a voltage detector 6 for detecting a DC bus voltage, and a control unit 7 for detection and control by the voltage detector 6. The voltage information transmitted to the unit 20, 8 is P for driving the inverter unit created by the control unit 20.
The WM signal, 9 is detected by the current detector 4 and the control unit 20
Current information transmitted to the control unit 20, reference numeral 30 is a setting device for giving control parameters and speed commands to the control unit 20, and reference numeral 11 is an induction motor connected to the inverter device.

FIG. 10 is a block diagram showing the inside of a control unit of a conventional inverter device. In the figure, reference numeral 12 is a PWM signal generator for generating and outputting a PWM signal 8 for driving the inverter unit 3 based on the result calculated by the microcomputer 35, and 13 is a current value detected by the current detector 4. Is transmitted to the microcomputer 35, 14 is an input interface for transmitting parameters and speed commands input to the setter 30 to the microcomputer 35,
Reference numeral 35 is a microcomputer that calculates the output frequency, output voltage, and acceleration / deceleration time of the inverter device based on the output current value, DC bus voltage, and speed specification, 36 is a ROM that stores the calculation program executed by the microcomputer 35, and 37 is RAM as a work area used when executing calculations with the microcomputer 35
Is.

Next, the operation will be described. In FIG. 9, the converter unit 1 converts the three-phase AC voltage into a DC voltage, and the capacitor 2 smoothes the DC voltage. The smoothed DC voltage is constantly detected by the voltage detector 6 and transmits the value of the DC bus voltage to the control unit 20. The inverter unit 3 converts a DC voltage into an AC voltage according to the PWM signal 8 output by the control unit 20, and drives the induction motor 11 connected to the inverter device. At this time, the current supplied from the inverter device to the induction motor 11 is detected by the detector 4
The output current value is constantly transmitted to the control unit 20.

In FIG. 10, in the microcomputer 35, the speed command and the parameter input to the setter 30 are detected via the input interface 14, and the value of the output current detected by the current detector 4 is detected via the input interface 13. The value of the DC bus voltage detected by the device 6 is received via the input interface 18. Next, according to the program stored in the ROM 36 based on the speed command and the parameter, the RAM 37 is used for the calculation, and the calculation result is calculated as PW.
It is sent to the M signal generator 12. In the PWM signal generator 12, the PW is calculated based on the calculation result sent from the microcomputer 35.
The M signal is generated and output to the inverter unit 3.

When it is determined that the value of the output current detected by the current detector 4 exceeds the current limit level calculated by the microcomputer 35, the induction motor 11 is controlled to keep the output current below the current limit level. The output frequency calculated from the acceleration / deceleration time is corrected and output so as to reduce the slip. When the output current becomes smaller than the current limit level, the actual output frequency output from the inverter unit 3 is restored up to the output frequency calculated from the acceleration / deceleration time. Even in the current limiting operation, if it is determined that the output current value exceeds the overcurrent protection level calculated by the microcomputer 35, the microcomputer 35 issues an output cutoff command to the PWM signal generation device 12 to cut off the inverter unit and protect it. To do.

When the voltage detector 6 determines in the microcomputer that the value of the DC bus voltage exceeds the overvoltage protection level, the microcomputer 35 outputs an output cutoff command to the PWM signal generating device 12, and the inverter section is output. Block and protect.

A conventional means for automatically adjusting the acceleration time and the deceleration time in the inverter device which operates as described above will be described. First, a fixed value determined by the designer is set as the initial value of the acceleration time or the deceleration time, and the output current value from the inverter unit 3 detected by the current detector 4 and a value lower than the overcurrent protection level are set in advance. Compare the current limit levels, and if a current smaller than the current limit level is flowing,
90% of the previously calculated acceleration time or deceleration time is set as the current acceleration time or deceleration time. On the contrary, when a large current is flowing, the previous 110% is set as the current acceleration time or deceleration time. The current output from the inverter unit 3 to the induction motor 11 becomes larger as the acceleration time or deceleration time becomes faster, and becomes smaller as the acceleration time or deceleration time becomes faster. Therefore, by repeating this processing until the acceleration or deceleration processing ends, the current limit level is averaged. The time is adjusted so that the output current of the device flows.

Next, conventional means for preventing the overvoltage protection from operating during deceleration in the above-described inverter device will be described. Using the DC voltage detected by the voltage detector 6 as the current DC bus voltage, the DC bus voltage change amount ΔV is obtained from the previous DC bus voltage, and the ΔV is calculated.
Then, the DC bus voltage increase determination value VH calculated from the DC bus voltage of this time is compared, and if ΔV is smaller than VH, 90% of the previously calculated deceleration time is set as the current deceleration time. On the contrary, if it is larger, 110% of the previous deceleration time is set as the current deceleration time. This process is repeated until the deceleration process ends, and the deceleration time is adjusted so that the DC bus voltage does not rise to the overvoltage protection level.

A conventional current limiting operation in the inverter device which operates as described above will be described. The output current exceeding the current limit level is output from the inverter unit 3 to the induction motor 1
When it flows to 1, the process of extending the acceleration time and the deceleration time to reduce the output current is performed as described above, but if the increase of the output current cannot be suppressed, the output frequency calculated by the acceleration time and the deceleration time is changed. Modify so that the output current becomes smaller. When the output current becomes smaller than the current limit level, the correction amount of the output frequency is restored. The acceleration / deceleration time for recovery is calculated by a fixed value determined by the designer.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a device which can appropriately perform acceleration / deceleration by an inverter device.

The first invention is to set the acceleration time or deceleration time.
The purpose is to obtain a device that allows the user to adjust appropriately.

The second aspect of the invention is to set the acceleration time or deceleration time.
It is an object of the present invention to provide a device that can be appropriately adjusted by a user and can perform acceleration / deceleration according to a load.

A third aspect of the invention is to set the acceleration time or deceleration time.
It is an object of the present invention to provide a device that allows a user to appropriately adjust the lower limits of acceleration time and deceleration time separately.

A fourth aspect of the invention is to set the acceleration time or the deceleration time.
It is an object of the present invention to provide a device that allows the user to adjust appropriately and set a reference value for maximizing or shortening the deceleration time.

A fifth aspect of the invention is to set the acceleration time or deceleration time.
It is possible to obtain a device that allows the user to adjust appropriately and uses the average value of the acceleration / deceleration time before current limitation for the control of the acceleration / deceleration time in the recovery of the output frequency after the current limiting operation, so that the frequency changes smoothly. To aim.

[0017]

According to a first aspect of the invention, a user intentionally sets a rate at which the acceleration time or the deceleration time is changed.
A change rate setting means that can be set is provided , and the change rate setting means
So that the rate of change during acceleration and deceleration can be set separately
It was done.

The second invention is acceleration time or deceleration time.
Change rate that allows the user to intentionally set the rate at which
Setting means is provided, and the change rate setting means reduces acceleration and decrease.
In addition to setting the rate of change at high speed separately, a means for setting the initial value of acceleration time or deceleration time is provided ,
The initial value of acceleration time and deceleration time by the initial value setting means
The initial value of is set separately .

The third invention is acceleration time or deceleration time.
Change rate that allows the user to intentionally set the rate at which
Setting means is provided, and the change rate setting means reduces acceleration and decrease.
The lower limit value of the acceleration time is set by the lower limit value setting means by setting the lower limit value of the acceleration time or the deceleration time while separately setting the rate of change at high speed.
And the lower limit of deceleration time are set separately .

A fourth invention is acceleration time or deceleration time.
Change rate that allows the user to intentionally set the rate at which
Setting means is provided, and the change rate setting means reduces acceleration and decrease.
The rate of change at high speed is set separately, and means for setting a reference value for determining whether to extend or shorten the deceleration time is provided.

A fifth aspect of the present invention is acceleration time or deceleration time.
Change rate that allows the user to intentionally set the rate at which
Setting means is provided, and the change rate setting means reduces acceleration and decrease.
The rate of change at high speed is set separately, and in the output frequency recovery operation after current limitation, the output frequency is restored by the average value of the excessive deceleration time before current limitation.

[0022]

The means for setting the rate of change of the acceleration / deceleration time of the electric motor can intentionally change the rate of change of the acceleration / deceleration time. The acceleration / deceleration time of the electric motor can be adjusted by setting the initial value of the acceleration / deceleration time of the electric motor and the lower limit of the acceleration / deceleration time. The deceleration time of the electric motor can be easily adjusted depending on whether the regenerative brake is used or not by means of setting a reference value that serves as a reference for determining whether to increase or decrease the deceleration time of the electric motor. . The means for adjusting the current limit recovery operation to the average value of the acceleration / deceleration time of the electric motor has the effect of smoothly changing the output frequency even in the situation where the acceleration / deceleration time is changing.

[0023]

EXAMPLE 1 An example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an inverter device according to an embodiment of the present invention. In the figure, 1 is a converter section for converting an AC voltage into a DC voltage, 2 is a capacitor for smoothing the voltage converted by the converter section, 3 is a bridge-connected transistor and a diode, and is smoothed by a smoothing capacitor 2. An inverter unit for reconverting the DC voltage into the AC voltage, 4 is a current detector for detecting the current supplied from the inverter unit to the induction motor 11, and 5 is a control unit for generating a signal for driving the inverter unit 3, 6 Is a voltage detector for detecting the DC bus voltage, 7 is voltage information detected by the voltage detector 6 and transmitted to the control unit 5, 8 is a PWM signal for driving the inverter unit generated by the control unit, and 9 is a current Current information detected by the detector 4 and transmitted to the control unit 5, 10 is a setting device for giving control parameters and speed commands to the control unit 5, 11 An induction motor connected to the inverter device.

FIG. 2 is a block diagram showing the inside of the control unit 5 of the inverter device according to the embodiment of the present invention. In the figure, reference numeral 12 is a PWM signal generation device for generating and outputting a PWM signal 8 for driving the inverter unit 3 based on the result calculated by the microcomputer 15, and 13 is a current detector 4
The input interface for transmitting the current value detected by the microcomputer 15 to the microcomputer 15, 14 is an input interface for transmitting the parameters and speed command input to the setter to the microcomputer 15, and 15 is the output current value, DC bus voltage, and speed specification. Based on the output frequency, output voltage of the inverter device,
A microcomputer for calculating the acceleration / deceleration time, a ROM 16 for storing a calculation program executed by the microcomputer 15, and a RAM 17 as a work area used when the microcomputer 15 executes the calculation.

Next, the operation will be described. In FIG. 1, a converter unit 1 converts a three-phase AC voltage into a DC voltage, and a capacitor 2 smoothes the DC voltage converted. This smoothed DC voltage is constantly detected by the voltage detector 6 and transmits the value of the DC bus voltage to the control unit 5. The inverter unit 3 converts a DC voltage into an AC voltage in accordance with the PWM signal 8 output by the control unit 5, and drives the induction motor 11 connected to the inverter device. At this time, the current supplied from the inverter device to the induction motor 11 is detected by the detector 4, and the output current value is always transmitted to the control unit 5.

In FIG. 2, the microcomputer 15 detects the speed command and parameters input to the setting device 10 via the input interface 14 and the output current value detected by the current detector 4 via the input interface 13 to detect the voltage. The value of the DC bus voltage detected by the device 6 is received via the input interface 18. Next, according to the program stored in the ROM 16 based on the speed command and parameters, the RAM 17 is used to perform the operation, and the operation result is PWM.
It is sent to the signal generator 12. In the PWM signal generator 12, PWM is performed based on the calculation result sent from the microcomputer 15.
A signal is created and output to the inverter unit 3.

When it is determined that the value of the output current detected by the current detector 4 exceeds the operation result current protection level in the microcomputer 15, the microcomputer 15 outputs an output cutoff command to the PWM signal generator 12. Then, the inverter unit 3 is shut off and protected. If the voltage detector 6 determines that the value of the DC bus voltage exceeds the overvoltage protection level as a result of calculation in the microcomputer, the microcomputer 15 outputs an output cutoff command to the PWM signal generation device 12, and the inverter unit 3 is turned off. Block and protect.

In the inverter device which operates as described above, the controller 5 sets the rate of change of acceleration / deceleration time, the initial value, and the lower limit value by the setter 10, and the set value is set in the microcomputer 15 via the input interface. Tell.

When the rate of change of the acceleration / deceleration time is set, the microcomputer 15 stores the set value in the RAM 17 and uses the output current value from the inverter unit 3 detected by the current detector 4 and the overcurrent protection level in advance. Is compared with the current limit level set to a lower value, and if a current smaller than the current limit level flows, the acceleration time and deceleration time calculated last time are shortened by the ratio stored in the RAM 17, and the current acceleration / deceleration is set. Time. If the rate of change at the time of acceleration and that at the time of deceleration are set separately, the acceleration / deceleration characteristic according to the set value can be obtained. FIG. 3 is a diagram showing a difference in acceleration characteristic when the rate of change of the acceleration / deceleration time according to the embodiment of the first invention is changed. According to this embodiment, the user can intentionally set the rate of change of the acceleration time and the rate of change of the deceleration time, so that the time from the start of acceleration to the end of acceleration or the time from the start of deceleration to the end of deceleration is adjusted. Therefore, it is possible to obtain the acceleration / deceleration time of the inverter that matches the characteristics of the peripheral device.

When the initial value of the acceleration / deceleration time is set, the microcomputer 15 stores the set value in the RAM 17. The initial value stored in the RAM 17 is processed as the acceleration or deceleration first acceleration time or deceleration time, and thereafter the acceleration / deceleration time is calculated by the same processing as described above. FIG. 4 is a diagram showing a difference in acceleration characteristic when the initial value of the acceleration / deceleration time according to the embodiment of the second invention is changed. According to this embodiment, since the initial value of the acceleration time and the initial value of the deceleration time can be set separately, it is possible to perform acceleration and deceleration according to the load applied when the inverter starts acceleration or starts deceleration.

When the lower limit value of the acceleration / deceleration time is set, the microcomputer 15 first stores the set value in the RAM 17.
Acceleration / deceleration time calculated by the same process as above
When it becomes smaller than the lower limit value stored in 17, the lower limit value is set as the acceleration time or the deceleration time, and in any case,
Make sure that the acceleration / deceleration time does not become shorter than the lower limit value. FIG. 5 is a diagram showing a difference in acceleration / deceleration characteristics when the lower limit value of the acceleration / deceleration time according to the third embodiment of the invention is changed. In the figure, the solid line shows the case of the lower limit.
The broken line shows the case where the lower limit is not used. According to this embodiment, since the lower limit values of the acceleration time and the deceleration time can be set separately, it is possible to prevent the peripheral equipment from being damaged or abruptly worn due to excessive sudden acceleration of the inverter.

Embodiment 2 FIG. 6 is a flow chart when a DC bus voltage is used as a reference for automatic adjustment of deceleration time according to an embodiment of the fourth invention. This will be described below with reference to FIG. In the inverter device, a DC voltage that serves as a reference for determining whether to increase or decrease the deceleration time is set by the setter 10, and the set value is transmitted to the microcomputer 15 via the input interface. In the microcomputer 15, first, in S101, the initial value of the deceleration time is set. Next, in S102, the value of the DC bus voltage detected by the voltage detector 6 is fetched into the microcomputer through the input interface, and in S103 the fetched value is compared with the reference value set by the setter. As a result of the comparison, if the DC bus voltage exceeds the reference value, the deceleration time is set to the maximum deceleration time, and if not, the deceleration time is shortened. This process is repeated until the deceleration ends. By the process of shortening the deceleration time or maximizing it, the deceleration time can be adjusted according to the value of the DC bus voltage during deceleration,
Moreover, the amount of increase in the DC bus voltage during deceleration can be adjusted by changing the reference value of the DC bus voltage.
FIG. 7 shows a deceleration characteristic when the reference value of the DC bus voltage is changed depending on the presence or absence of a regenerative brake in the means for adjusting the deceleration time according to the reference value of the DC bus voltage according to the embodiment of the fourth invention. FIG. According to this example,
Since the DC bus voltage level can be set to maximize or shorten the deceleration time, the rise in DC bus voltage can be adjusted by the set value, and there is a device that consumes the regenerative energy returned from the motor. It is possible to obtain the deceleration time that matches the case where there is no case.

Embodiment 3 FIG. 8 is a diagram for explaining a recovery operation after current limitation with an average value of acceleration / deceleration time according to an embodiment of the fifth invention. In the inverter device, when the output current from the inverter unit 3 becomes larger than the current limit level, the output current is suppressed to be smaller than the current limit level. Therefore, in order to reduce slip of the induction motor 11, the output frequency obtained from the acceleration time during acceleration is reduced. Is reduced, and the output frequency obtained by the deceleration time is increased during deceleration. When the current becomes lower than the limit level, the frequency is restored to the output frequency that should be output, which is calculated by the acceleration time and the deceleration time. As the acceleration / deceleration time until the output frequency is recovered at this time, the average value of the acceleration / deceleration time before the current limit is activated is used so that the output current is stabilized. By this processing, the operation of the output frequency after the current limitation becomes smooth. According to this embodiment, since the average value of the acceleration / deceleration time before the current limitation is used for the acceleration / deceleration time in the recovery of the output frequency after the current limiting operation, the frequency changes smoothly and the output current can be stabilized. Becomes

[0034]

Effect of the Invention According to the first invention, since the separate User <br/> over The rate of change or rate of change of the deceleration time of the acceleration time during acceleration and deceleration is to be intentionally set It is possible to appropriately adjust the time from the start of acceleration to the end of acceleration or the time from the start of deceleration to the end of deceleration, and it is possible to obtain the acceleration / deceleration time of the inverter that matches the characteristics of peripheral devices.

According to the second aspect of the invention, the rate of change of the acceleration time or
Alternatively, the rate of change of deceleration time can be used separately for acceleration and deceleration.
Can be set intentionally, the initial value of acceleration time,
Since the initial value of the deceleration time can be set separately, peripherals
While obtaining the acceleration / deceleration time of the inverter that matches the characteristics,
It is possible to perform acceleration and deceleration according to the load applied when the inverter starts acceleration or deceleration.

According to the third invention, the rate of change of the acceleration time or
Alternatively, the rate of change of deceleration time can be used separately for acceleration and deceleration.
Can be set intentionally, and the initial values of acceleration time and deceleration time can be set separately, so it can be set according to the characteristics of peripheral devices.
It becomes possible to obtain the acceleration / deceleration time of the inverter as well as to prevent the peripheral equipment from being damaged or abruptly worn due to excessive sudden acceleration of the inverter.

According to the fourth invention, the rate of change in acceleration time or
Alternatively, the rate of change of deceleration time can be used separately for acceleration and deceleration.
Can be set intentionally and the reference value for maximizing or shortening the deceleration time can be set .
While obtaining the acceleration / deceleration time of the inverter that matches the characteristics,
The rise of the DC bus voltage can be adjusted by the reference value set value, and it is possible to obtain the deceleration time depending on the case where there is a device that consumes the regenerative energy returned from the motor and the case where it does not.

According to the fifth aspect of the invention, the rate of change of the acceleration time or
Alternatively, the rate of change of deceleration time can be used separately for acceleration and deceleration.
Can be set intentionally, and the average value of the acceleration / deceleration time before current limitation is used for the acceleration / deceleration time in the recovery of the output frequency after current limiting operation, so it matches the characteristics of peripheral devices.
In addition to obtaining the acceleration / deceleration time of the inverter, the frequency changes smoothly and the output current can be stabilized.

[Brief description of drawings]

FIG. 1 is a block diagram of an inverter device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the inside of the control unit of the inverter device according to the embodiment of the present invention.

FIG. 3 is a diagram showing a difference in acceleration characteristic when changing a rate of change in acceleration time by means for setting a rate of change in acceleration / deceleration time according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a difference in acceleration characteristic when an initial value of acceleration / deceleration time is changed by means for setting a lower limit value of acceleration / deceleration time according to the embodiment of the second invention.

FIG. 5 is a diagram showing a difference in acceleration / deceleration characteristics when a lower limit value of acceleration / deceleration time is set by means for setting a lower limit value of acceleration / deceleration time according to the embodiment of the third invention.

FIG. 6 is a flowchart showing the operation of the means for adjusting the deceleration time so that the overvoltage protection does not operate according to the reference value of the DC bus voltage according to the embodiment of the fourth invention.

FIG. 7 is a diagram showing deceleration characteristics when a reference value of a DC bus voltage according to an embodiment of the fourth invention is changed depending on whether a regenerative brake is present or absent.

FIG. 8 is a diagram illustrating a recovery operation after current limitation by an average value of acceleration / deceleration time according to an embodiment of the fifth invention.

FIG. 9 is a block diagram of a conventional inverter device.

FIG. 10 is a block diagram showing the inside of a control unit of a conventional inverter device.

[Explanation of symbols]

1 converter section, 2 smoothing capacitor, 3 inverter section, 4 current detector, 5 control section, 6 voltage detector,
8 PWM signal, 10 setting device, 11 induction motor, 1
5 microcomputer, 16 ROM, 17 RAM, 20 control unit, 30 setting device, 35 microcomputer, 36 ROM,
37 RAM.

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Claims (5)

(57) [Claims] 1. A converter section for converting an AC input into a DC output, an inverter section for receiving a DC output of the converter section as an input and converting the AC output into an AC output for supplying to a motor, and a voltage for detecting a DC output voltage. A detector, a current detector for detecting a current supplied from the inverter unit to the electric motor, and means for adjusting the acceleration time or the deceleration time according to the detection values from the voltage detector and the current detector,
A change rate setting means is provided which allows the user to intentionally set the rate of changing the acceleration time or deceleration time of the electric motor , and the change rate setting means changes the rate of change during acceleration and deceleration.
The inverter device is characterized in that the above is set separately . 2. An initial value setting means for setting an initial value of acceleration time or deceleration time of the electric motor is provided , and the initial value setting means is provided .
Initial value of acceleration time and initial value of deceleration time are separately set for each step
The inverter apparatus according to claim 1, characterized in that it has to set. 3. A lower limit value setting means for setting a lower limit value of acceleration time or deceleration time of the electric motor is provided , and the lower limit value setting means is provided .
Lower limit of acceleration time and lower limit of deceleration time are separately set for each step
The inverter apparatus according to claim 1, characterized in that it has to set. 4. The inverter device according to claim 1, further comprising means for setting a reference value for determining whether to increase or decrease the deceleration time of the electric motor. 5. The inverter device according to claim 1, wherein in the output frequency recovery operation after the current limit, the output frequency is recovered by an average value of the overdeceleration time before the current limit.