JPH06133592A - Inverter device - Google Patents

Abstract

PURPOSE:To efficiently accelerate and decelerate an inverter device by performing the acceleration and deceleration in a short time within such an extent that the inverter function of the device does not stop due to overcurrent protection and, at the same time, constantly maintaining the magnitude of the supplying current. CONSTITUTION:This inverter device is provided with a converter section 101 which converts an AC voltage into a DC voltage, capacitor 102 which smoothes the DC voltage converted by the section 101, inverter section 103 which inputs the DC voltage smoothed by the capacitor 102 and converts the DC voltage into an AC voltage, and current detector 104 which detects the current supplied to an induction motor 111 from the section 103 and the section 103 is disconnected and protected when the current value detected by the current detector 104 exceeds a prescribed value. In addition, the inverter device is also provided with a control section 107 which starts the acceleration or deceleration of the inverter device within specific accelerating or decelerating time and controls the acceleration or deceleration at every unit time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device whose output voltage and output frequency can be freely controlled, and more specifically, it automatically adjusts acceleration time or deceleration time to accelerate or decelerate in a short time. The present invention relates to an inverter device.

[0002]

2. Description of the Related Art A conventional inverter device includes a converter section for converting an AC voltage into a DC voltage and a smoothing section for smoothing the DC voltage converted by the converter section in order to freely control an output voltage and an output frequency. It is composed of a capacitor and an inverter unit that reconverts the DC voltage smoothed by the capacitor into an AC voltage. In addition, it is equipped with a current detector that detects the output current value of the inverter unit (current value that is supplied to the electric motor connected to the inverter device) and a DC voltage detector that detects the voltage value of the DC voltage. , If the current value detected by the current detector exceeds the specified overcurrent protection level, or if the voltage value detected by the DC voltage detector exceeds the specified overvoltage protection level, protect the inverter section. In order to do so, the inverter unit is cut off.

When an induction motor is driven by an inverter device, when a speed command and acceleration time and deceleration time are set as parameters using a setter and the operation is started, as shown in FIG.
As shown in, the output frequency of the inverter device accelerates to the speed command value in the acceleration time, and when the operation ends, the output frequency of the inverter device decelerates in the deceleration time and stops. At this time, if the setting of the acceleration time or the deceleration time is made too short, the output current will flow too much during the acceleration or the deceleration, the operation of the overcurrent protection will operate, and the inverter unit will be cut off. Or if you set the deceleration time too short,
During deceleration, the regenerative energy activates the overvoltage protection operation, which shuts off the inverter. In order to perform the shortest acceleration and deceleration while maximizing torque output while the inverter is not shut down, the acceleration time and deceleration time must be determined by trial and error while observing the output current status and DC bus voltage status. Had to decide.

As a device for automatically determining the deceleration time in consideration of the DC bus voltage, there is a "voltage type pulse width modulation inverter device" disclosed in Japanese Patent Laid-Open No. 58-51775. In this voltage-type pulse-width modulation inverter device, the DC line voltage supplied to the inverter unit is detected, the deceleration characteristic is made gentle every time the detected voltage value exceeds a predetermined voltage value, and the voltage is reduced to the predetermined voltage value. Each time it returns, the deceleration characteristic is restored.

In addition, as a reference technical document related to the present invention, there is "acceleration / deceleration control method and apparatus for servo motor" disclosed in Japanese Patent Laid-Open No. 3-36977.

[0006]

Since the conventional inverter device is configured as described above, the acceleration time and the deceleration time are determined by repeating trial and error while observing the output current and the DC bus voltage. However, there was a problem that it was inefficient.

Further, in Japanese Patent Laid-Open No. 58-51775, the deceleration characteristic is made gentle every time the detected voltage value exceeds a predetermined voltage value. However, if the deceleration characteristic is made gentle, the deceleration time becomes long and the efficiency is reduced. There was a problem that was bad.

The present invention has been made in order to solve the above-mentioned problems, and accelerates and decelerates in a short time within a range where the inverter function is not stopped by overcurrent protection, and supplies the power. An inverter that achieves efficient acceleration and deceleration by maintaining a constant amount of current, and that achieves efficient deceleration by performing deceleration in a short time within a range where the inverter function does not stop due to overvoltage protection. The purpose is to obtain the device.

[0009]

In order to achieve the above-mentioned object, an inverter device according to the present invention comprises a first converting means for converting an AC voltage into a DC voltage, and a DC converting by the first converting means. Smoothing means for smoothing the voltage, second converting means for inputting the DC voltage smoothed by the smoothing means and converting into AC voltage, and current detecting means for detecting the current supplied from the second converting means to the electric motor. In the inverter device, which is provided with and which protects the second conversion means by shutting it off when the current value detected by the current detection means exceeds a predetermined current value, starts acceleration or deceleration at a predetermined acceleration time or deceleration time. However, a control means for controlling the acceleration time or the deceleration time for each unit time is provided.

The control means compares the output current value from the second conversion means with a comparison value which is determined to be smaller than a predetermined current value in advance, and the output current value of the second conversion means is larger. In this case, the acceleration time or deceleration time within the unit time is lengthened, and when the output current value of the second conversion means is smaller, the acceleration time or deceleration time within the unit time is shortened.

The inverter device according to the present invention is
To achieve the above object, first conversion means for converting an AC voltage into a DC voltage, smoothing means for smoothing the DC voltage converted by the first conversion means, and DC voltage smoothed by the smoothing means And a voltage detecting unit for detecting a DC voltage input to the second converting unit, and the voltage value detected by the voltage detecting unit is a predetermined voltage value. In the inverter device that shuts off and protects the second conversion means when the value exceeds, deceleration is started at a predetermined deceleration time, and control means for controlling the deceleration time for each unit time is provided.

When the value of the DC voltage input to the second conversion means is less than or equal to the predetermined first comparison voltage value, the control means has a predetermined determination value and unit time. And the rise value of the DC voltage are compared with each other, and when the first comparison voltage value is exceeded, the first comparison voltage value becomes the determination value and the second comparison voltage value is determined to be smaller than the predetermined voltage value in advance. The determination value having a proportional relationship according to the value of the DC voltage input to the second conversion means and the increase value of the DC voltage within the unit time so that the value becomes 0 when the comparison voltage value of In both cases, if the rise value of DC voltage is larger, the deceleration time within the unit time is lengthened, and if the rise value of DC voltage is smaller within the unit time. Shorten the deceleration time of.

The value at the start of the acceleration time or the deceleration time is the average value of the acceleration time or the deceleration time which is successively changing at the previous acceleration or deceleration.

[0014]

The inverter device according to the present invention starts acceleration or deceleration in a predetermined acceleration time or deceleration time,
A value smaller than a predetermined overcurrent protection value is compared with the output current of the inverter device, and if the output current of the inverter unit is larger, the acceleration time or deceleration time within a unit time is lengthened and the inverter unit If the output current is smaller, shorten the acceleration time or deceleration time within the unit time.

Further, the inverter device according to the present invention is
When deceleration is started for a predetermined deceleration time and the value of the DC voltage input to the inverter unit is equal to or less than the predetermined first comparison voltage value, the predetermined judgment value and unit time If the value of the DC voltage input to the inverter unit exceeds the first comparison voltage value by comparing with the rise value of the DC voltage, it becomes a predetermined judgment value for the first comparison voltage value. ,
A judgment value having a proportional relationship according to the value of the DC voltage input to the inverter unit so that the value becomes 0 when the second comparison voltage value that is determined to be smaller than the voltage value for overvoltage protection is exceeded. And the rise value of the DC voltage in the unit time are compared, and when comparing with any of the judgment values, if the rise value of the DC voltage is larger, the deceleration time in the unit time is lengthened and the When the rising value is smaller, the deceleration time within the unit time is shortened.

As the acceleration time or the deceleration time at the start, the average value of the acceleration time or the deceleration time which has been sequentially changed last time is used.

[0017]

[Embodiment 1] An embodiment of the present invention will be described below in detail with reference to the drawings. 1 is a block diagram showing a configuration of an inverter device showing a first embodiment of the present invention. In the figure, 101 is a converter unit that converts an AC voltage into a DC voltage, 102 is a capacitor that smoothes the DC voltage converted by the converter unit 101, 103 is a bridge-connected transistor and a diode, and is smoothed by the capacitor 102. Inverter unit for reconverting the DC voltage into AC voltage, 104 is a current detector for detecting the output current of the inverter unit 103, 105 is a voltage detector for detecting the DC bus voltage, and 106 is a parameter or speed command for control. A setting unit for setting, a control unit 107 for creating a signal for driving the inverter unit 103,
108 is detected by the voltage detector 105 and is controlled by the control unit 107.
Voltage information transmitted to the control unit 109, a PWM signal generated by the control unit 107 for driving the inverter unit 103, 1
Reference numeral 10 is current information detected by the current detector 104 and transmitted to the control unit 107, and reference numeral 111 is an induction motor connected to the inverter unit 103.

FIG. 2 is a block diagram showing the configuration of the control unit 107 shown in FIG. In FIG. 2, 201 is a PWM signal 109 for driving the inverter unit 103.
A PWM signal generating device for generating and outputting the signal, 202 performs various interfaces with the setting device 106,
Input I / F (interface) for fetching parameters and speed commands input to 6 into the control unit 107, 2
03 performs various interfaces with the current detector 104, and the current information 11 detected by the current detector 104
Input I / F for fetching 0 into the control unit 107, 2
Reference numeral 04 denotes various interfaces with the voltage detector 105, and the voltage information 10 detected by the voltage detector 105
Input I / F for taking 8 into the control unit 107, 2
Reference numeral 05 is a ROM storing a control program, 206 is a RAM as a work area, 207 is current information 110,
It is a microcomputer that inputs the voltage information 108 and the speed command and calculates the output frequency, the output voltage, the acceleration time, and the deceleration time of the inverter unit 103 based on the control program stored in the ROM 205.

Next, the operation will be described. In FIG. 1, a converter unit 101 converts a three-phase AC voltage into a DC voltage, and the DC voltage converted by the converter unit 101 is smoothed by a capacitor 102. This smoothed DC voltage is always detected by the voltage detector 105, and the value of the DC bus voltage is output to the control unit 107 by the voltage information 108. In the inverter unit 103, the DC voltage smoothed by the capacitor 102 is converted into an AC voltage in accordance with the PWM signal 109 output from the control unit 107, and the inverter unit 1
The induction motor 111 connected to 03 is driven. At this time, the current supplied from the inverter unit 103 to the induction motor 111 is detected by the current detector 104, and the value of the output current of the inverter unit 103 is always output to the control unit 107 based on the current information 110.

In FIG. 2, the microcomputer 20
7, the value of the output current of the inverter unit 103 detected by the current detector 104 is input via the input I / F 202 to the speed command and parameters input to the setting unit 106, and the input I / F 2
03, the value of the DC bus voltage detected by the voltage detector 105 is received via the input I / F 204. Next, based on the speed command and parameters, the RAM 206 is used to perform an operation based on the control program stored in the ROM 205, and the operation result is output to the PWM signal generating device 2.
Output to 01. The PWM signal creation device 201 creates the PWM signal 109 based on the calculation result sent from the microcomputer 207 and outputs it to the inverter unit 103.

When the value of the output current of the inverter 103 detected by the current detector 104 is judged to exceed the overcurrent protection level as a result of calculation by the microcomputer 207, the microcomputer 207 creates a PWM signal. An output cutoff command is output to the device 201 to cut off and protect the inverter unit 103. If the voltage detector 105 determines that the value of the DC bus voltage exceeds the overvoltage protection level as a result of the calculation by the microcomputer 207, the microcomputer 207 outputs P
An output cutoff command is output to the WM signal generation device 201,
Protect the inverter by shutting it off.

Means for automatically adjusting the acceleration time or the deceleration time in the inverter device which operates as described above will be described with reference to the flowchart of FIG. The flowchart of FIG. 3 is for adjusting the acceleration time or the deceleration time for each cycle (predetermined constant time interval). In FIG. 3, first, an initial value of the acceleration time or the deceleration time when starting acceleration or deceleration is set (S30).
1). This initial value may be a fixed value determined by the designer in advance.
Next, the input I / F 20 detected by the current detector 104
The value of the output current of the inverter unit 103 input to the microcomputer 207 via 3 is compared with a current limit level set to a value lower than the overcurrent protection level in advance to determine whether the output current exceeds the limit level. Judge (S30
2). When a current smaller than the current limit level is flowing, 90% of the acceleration time or deceleration time of the previous cycle, that is, the previous cycle is set as the current acceleration time or deceleration time (S303). In this case, the output current increases more than the previous time. When a current larger than the current limit level is flowing, 110% of the acceleration time or deceleration time of the previous cycle, that is, the previous cycle is set as the current acceleration time or deceleration time (S304). In this case, the output current will be lower than it was last time. Then, the above S303 or S3
Acceleration processing or deceleration processing is performed according to the current acceleration time or deceleration time determined in 04 (S305). Finally, it is determined whether or not the acceleration process or the deceleration process is completed (S306), and the processes from S302 to S306 are repeated until the completion.

By repeating the processes from S302 to S306, as shown in FIG. 4, the output current expands and contracts in a time near the acceleration time and deceleration time at which the output current reaches a predetermined limit level, and on average. The time is adjusted so that the output current of about the limit level flows. A, b in FIG.
In c, d, e and h, the output current does not exceed the limit level, and thus the time is reduced. That is, it indicates that the time required for acceleration or deceleration is reduced. Further, f and g in the figure extend the time because the output current exceeds the limit level. That is, it indicates that the time required for acceleration or deceleration is increased. In addition,
If the limit level value is set to the maximum value at which overcurrent protection does not work, the shortest acceleration or deceleration without overcurrent protection can be realized.

[Second Embodiment] Next, a second embodiment will be described. The configuration is similar to that of the first embodiment. When the induction motor is operated using the inverter device, energy is regenerated from the induction motor to the inverter unit 103 during deceleration, and the DC bus voltage of the inverter unit 103 rises. The DC bus voltage is detected by the voltage detector 105, is input to the microcomputer 207 via the input I / F 204, and the deceleration time is determined by the method described later so that the DC bus voltage is held at the maximum allowable value. By decelerating with, the shortest deceleration without overvoltage protection is realized.

FIG. 5 is a flow chart showing the operation of the means for adjusting the deceleration time so that the overvoltage protection does not work. A method for realizing the shortest deceleration will be described with reference to FIG. First, an initial value of deceleration time for deceleration is set (S501). The initial value of the deceleration time may be a fixed value determined by the designer in advance. Next, the voltage is detected by the voltage detector 105 and is input to the microcomputer 207 via the input I / F 204.
The DC bus voltage value input to is taken in and set as the DC bus voltage value this time (S502). When the current DC bus voltage value is determined this time, a value (ΔV) is calculated by subtracting the previous DC bus voltage value stored in S505, which will be described later, from the current DC bus voltage value (S503). Next, a DC bus voltage increase determination value (V _H ) is calculated based on the current DC bus voltage value according to FIG. 7 described later (S504).

FIG. 7 is a graph for obtaining the DC bus voltage increase judgment value when adjusting the deceleration time so that the overvoltage protection does not work. According to FIG. 7, as the DC bus voltage V _DC this time becomes closer to the voltage limit level (V _B ) which is previously set to a value lower than the overvoltage protection level (V _O ), the increase in the DC bus voltage is suppressed. To be decided.
V _B than to take the maximum value which can be tolerated, it is possible to realize a minimum reduction. The determination value (V _H ) is a constant value until the value of the DC bus voltage becomes V _A, and when the value of the DC bus voltage exceeds V _A , the relationship shown in the following formula 1 is used. The value obtained by the formula is used as the judgment value. V _A may be arbitrarily determined from experience values.

[0027]

[Equation 1]

For the next calculation, the current DC bus voltage fetched in S502 is stored as the previous DC bus voltage in the next time (S505). After that, S503
In comparing the V _H was determined by calculated [Delta] V and S504, [Delta] V
It is determined whether or not> V _H (S506). If ΔV is smaller than V _H , 90% of the previously calculated deceleration time is set as the current deceleration time (S507). If ΔV is larger than V _H , 110% of the previously calculated deceleration time is set as the current deceleration time (S508). Subsequently, deceleration processing is performed according to the calculated current deceleration time (S509). Finally, it is determined whether or not the deceleration processing is completed (S510), and the processing from S502 to S510 is repeated until it is completed.

By repeating the processes from S502 to S510, as shown in FIG. 6, if the DC bus voltage starts to decelerate and the DC bus voltage is sufficiently lower than the voltage limit level, the DC bus voltage rise determination value V _H If the deceleration time is shortened to a large extent and the DC bus voltage rise judgment value V _H is set so that the deceleration time cannot be shortened when the voltage approaches the voltage limit level, the DC bus voltage is reduced to the voltage limit level. The expansion and contraction are repeated in the vicinity of the deceleration time reaching, and as a result, the shortest deceleration is achieved by holding the maximum allowable DC bus voltage on average. In FIG. 6A, a, b, c, d, g, and j are shorter because the increase ΔV of the DC bus voltage is less than or equal to the determination value (V _H ). That is, it indicates that the time required for deceleration is reduced. In addition, e, f, h, and i in the figure extend the time because the increase ΔV of the DC bus voltage exceeds the determination value (V _H ). That is, it indicates that the time required for deceleration is increasing.

[Third Embodiment] Next, a third embodiment will be described. FIG. 8 is a graph showing a comparison between the case where the previous average value is used as the initial value of the acceleration time and the case where it is not used, and FIGS. 8A and 8B show the case where the average value is not used. 8 (c) and (d) are used. In the first and second embodiments described above, the initial value of the acceleration time at the start of acceleration is set to a fixed value. Therefore, when the initial value is far from the shortest acceleration time as shown in FIG. It takes time until the time converges to the shortest acceleration time, which is a waste of time. Therefore, the actual acceleration time is extended. Therefore,
As shown in FIG. 8C, the average value of the acceleration time that has sequentially changed from the previous stop state to the end of acceleration is calculated and stored, and when the next acceleration is performed, the average value is used as the initial value of the acceleration time. By doing so, it is possible to reduce the wasted time and the actual acceleration time.

Similarly, in deceleration, the wasted time can be reduced and the actual deceleration time can be shortened. According to this method, the more the acceleration or deceleration is repeated, the more wasted time can be reduced.

[Fourth Embodiment] Next, a fourth embodiment will be described. Although the three-phase inverter device is used in the first, second, and third embodiments, the invention is not particularly limited to this, and a single-phase or other multi-phase inverter device may be used. The same effect can be obtained even if the induction motor 111 is not an induction motor but a synchronous motor. Further, although the reduction rate of the acceleration time or the deceleration time is 90% in the first and second embodiments, it may be any value less than 100%. Further, although the extension ratio of the acceleration time or the deceleration time is 110%, it may be set to any value larger than 100%.

[0033]

As described above, according to the present invention, the first conversion means for converting the AC voltage into the DC voltage, the smoothing means for smoothing the DC voltage converted by the first conversion means, and the smoothing means. A second conversion means for inputting the DC voltage smoothed by the means and converting it into an AC voltage, and a current detection means for detecting the current supplied from the second conversion means to the electric motor are provided, and are detected by the current detection means. When the current value exceeds a predetermined current value, in the inverter device that shuts off and protects the second conversion means, acceleration or deceleration is started in a predetermined acceleration time or deceleration time, and the acceleration time or Since the control means for controlling the deceleration time is provided, efficient acceleration and deceleration can be performed.

According to the present invention, the first converting means for converting the AC voltage into the DC voltage, the smoothing means for smoothing the DC voltage converted by the first converting means, and the smoothing means for smoothing the DC voltage. It is provided with a second conversion means for inputting a DC voltage and converting it into an AC voltage, and a voltage detection means for detecting a DC voltage input to the second conversion means, and the voltage value detected by the voltage detection means has a predetermined value. Second when the voltage value is exceeded
In the inverter device that shuts off and protects the conversion means, the control means that starts deceleration at a predetermined deceleration time and controls the deceleration time for each unit time is provided, so that efficient deceleration can be performed.

[Brief description of drawings]

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

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

FIG. 3 is a flowchart showing the operation of the means for adjusting the acceleration time or the deceleration time so that the overcurrent protection according to the present invention does not work.

FIG. 4 is a graph showing changes in acceleration time or deceleration time adjusted so that overcurrent protection according to the present invention does not work.

FIG. 5 is a flowchart showing the operation of the means for adjusting the deceleration time so that the overvoltage protection according to the present invention does not work.

FIG. 6 is a graph showing changes in deceleration time and changes in DC bus voltage adjusted so that overvoltage protection according to the present invention does not work.

FIG. 7 is a graph for obtaining a DC bus voltage increase determination value when adjusting the deceleration time so that the overvoltage protection according to the present invention does not work.

FIG. 8 is a graph showing a comparison between a case where a previous average value is used as an initial value of an acceleration time or a deceleration time and a case where it is not used.

FIG. 9 is a graph showing acceleration time and deceleration time by a conventional inverter device.

[Explanation of symbols]

 103 Inverter Unit 104 Current Detector 105 Voltage Detector 107 Control Unit 201 PWM Signal Generation Device 207 Microcomputer

Claims (5)

[Claims] 1. A first conversion means for converting an AC voltage into a DC voltage, a smoothing means for smoothing the DC voltage converted by the first conversion means, and a DC voltage smoothed by the smoothing means. And a second conversion means for converting into an AC voltage and a current detection means for detecting a current supplied from the second conversion means to the electric motor, and the current value detected by the current detection means is a predetermined current. In the inverter device that shuts off and protects the second conversion means when the value exceeds the value, control for starting acceleration or deceleration for a predetermined acceleration time or deceleration time and controlling the acceleration time or deceleration time for each unit time An inverter device comprising means. 2. The control means compares the output current value from the second conversion means with a comparison value which is determined in advance to be smaller than the predetermined current value, and outputs the output current value from the second conversion means. Is longer, the acceleration time or deceleration time within the unit time is lengthened, and when the output current value of the second conversion means is smaller, the acceleration time or deceleration time within the unit time is shortened. The inverter device according to claim 1, wherein: 3. A first conversion means for converting an AC voltage into a DC voltage, a smoothing means for smoothing the DC voltage converted by the first conversion means, and a DC voltage smoothed by the smoothing means. And a voltage detecting unit for detecting a DC voltage input to the second converting unit, and the voltage value detected by the voltage detecting unit is a predetermined voltage value. In the case of an inverter device that shuts off and protects the second conversion means when the value exceeds
An inverter device comprising a control means for starting deceleration at a predetermined deceleration time and controlling the deceleration time for each unit time. 4. The control unit, when the value of the DC voltage input to the second conversion unit is less than or equal to a predetermined first comparison voltage value, a predetermined determination value and a unit. Compared with the rise value of the DC voltage within the time, when the first comparison voltage value is exceeded, the first comparison voltage value becomes the judgment value, and the predetermined voltage value is set in advance. Within a unit time and a judgment value having a proportional relationship in accordance with the value of the DC voltage input to the second conversion means so that it becomes 0 when the value of the second comparatively small voltage is exceeded. If the increase value of the DC voltage is greater than that of any of the judgment values, the deceleration time within the unit time is lengthened and the increase value of the DC voltage is The deceleration time within a unit time is shortened when it is small, and the in-line according to claim 3, Verta device. 5. The value at the start of the acceleration time or the deceleration time is an average value of the acceleration time or the deceleration time which is sequentially changing at the previous acceleration or deceleration. The inverter device according to 3 or 4.