JP3419190B2 - Inverter device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter for controlling the speed of a motor, and more particularly to an inverter for setting the rotation speed of the motor by an analog voltage signal. FIG. 8 is a block diagram of a conventional inverter device. In the figure, 50 is an inverter device, 51 is a converter unit for converting an AC voltage to a DC voltage, 52 is a smoothing capacitor for smoothing the voltage converted by the converter unit 51, 53 is a bridge-connected transistor and diode, An inverter unit for reconverting the DC voltage smoothed by the smoothing capacitor 52 into an AC voltage having a variable frequency; 54, a control unit for generating a signal for driving the inverter unit 53; 55, an inverter unit generated by the control unit 54 53, a PWM signal for driving 53,
Reference numeral 56 denotes a second unit which gives the control unit 54 a parameter for control.
Is an input interface, and 58 is an induction motor as a motor connected to the inverter device 50. Next, the operation will be described. The converter 51 converts the three-phase AC voltage into a DC voltage, and the DC voltage converted by the smoothing capacitor 52 is smoothed. The inverter 53 converts a DC voltage into an AC voltage having a variable frequency in accordance with the PWM signal 55 output from the control unit 54, and drives an induction motor 58 connected to the inverter device 50. FIG. 9 is a block diagram showing the inside of the control means 54. In the figure, 59 is a microcomputer for calculating the output frequency, output voltage and acceleration / deceleration time of the inverter device based on the frequency command, and 60 is a PWM for driving the inverter unit 53 based on the result calculated by the microcomputer 59. Signal 5
5, a PWM signal generating means for generating and outputting 5; 61, a ROM storing a calculation program to be executed by the microcomputer 59;
62 is a RAM as a work area used when the microcomputer 59 executes an operation, 63 is a parameter setting means 5
EER that stores control parameters such as a frequency command conversion value for the analog voltage input value set by step 6.
OM and 64 are analog voltage input terminals as first setting means, 65 is an A / D converter for converting an analog voltage input value input from the analog voltage input terminal into a digital value, and 66 is external contact signal input means. is there. Next, the operation will be described. Microcomputer 59
Receives the parameters set in the parameter setting means 56 via the input interface 57 and stores them in the EEPROM 63. Further, it receives the analog voltage input as a digital value via the A / D converter 65 and converts it into a frequency command value based on the conversion value stored in the EEPROM 63 in advance. Further, based on the frequency command, a control operation is performed in accordance with a program stored in the ROM 61, and the operation result is sent to the PWM signal generating means 60. The PWM creating means 60 creates a PWM signal based on the calculation result sent from the microcomputer 59 and outputs the PWM signal to the inverter 53. FIG. 10 is a diagram showing the relationship between the input voltage after the input voltage calibration and the output frequency. The relationship of the output frequency to the input voltage after the above-described input voltage calibration is a linear function as shown in the figure. Here, when an arbitrary voltage is input,
An output frequency is obtained according to the linear function. A process for converting an analog voltage command into a frequency command in the above-described conventional inverter device will be described. Before operating the inverter device, for example, as shown in FIG. 10, a frequency setting voltage bias and a gain setting for converting a frequency command corresponding to an analog voltage input value are performed. (This operation is hereinafter referred to as input voltage calibration.) First, a frequency setting voltage bias is set. An arbitrary voltage bias is input from the analog voltage input terminal 64, and an output frequency for the voltage bias is input from the setting means 56. The CPU 59 receives the write signal from the parameter setting means 56 and stores the voltage bias value converted into a digital value via the A / D converter 65 and the output frequency corresponding to the voltage bias value in the EEPROM 62. An arbitrary voltage gain input from the analog voltage input terminal 64 by a similar operation and an output frequency corresponding to the gain value are also stored in the EEPROM 62. FIG. 11 is a flowchart for converting a conventional inverter device into a frequency command. Next, a description will be given of a process of converting an analog voltage input value into a frequency command during operation of a conventional inverter device after input voltage calibration. The voltage bias value converted into a digital value in step S51 is taken in by the A / D converter 65. When a frequency command is made based on an analog voltage input value, noise affects the frequency command. In step S52, it is checked whether or not filtering is necessary to reduce the influence of the noise. If filtering is required, step S
At 53, the filter processing is always performed irrespective of the output frequency according to the set value set in advance by the parameter setting means 56, and then the process proceeds to step S54. Step S
If the filter processing is not performed in 52, the frequency command is converted in accordance with the linear function after input voltage calibration in step S54. Next, a description will be given of a frequency setting process of a conventional inverter device having a plurality of analog voltage input terminals. In an inverter device having a plurality of analog input voltage terminals 64, an analog voltage input from each terminal is converted into a digital value using an A / D converter 65. Is
Processing is performed so that the same frequency command is given for the same input voltage value, and is converted into a frequency using one type of linear function determined by the above-described input voltage calibration. [0010] The minute vibration of the input voltage is as follows.
The effect is greater when the motor is rotating at low speed than when it is rotating at high speed. If the conventional filter processing is set to suppress the fluctuation of the rotation speed due to the vibration of the command voltage at low rotation, the filter processing will be performed up to the high rotation area where the minute vibration of the input voltage is not affected. However, there has been a problem that the response to the frequency command is reduced. In the conventional apparatus, the frequency resolution for the input voltage can be set arbitrarily. However, since the calibration operation cannot be performed during the operation of the inverter, it is impossible to change the frequency resolution during the operation. Was. Further, even when a plurality of voltage input terminals are provided, only one terminal voltage calibration is performed, so that there is a problem that individual voltage input terminals cannot be corrected. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a first object of the present invention is to provide an inverter device capable of performing a filtering process to reduce the influence of noise in accordance with the number of rotations of a motor. What you get. A second object of the present invention is to provide an inverter device which can change the frequency resolution with respect to an input voltage even during operation and can easily control the speed of an induction motor by analog voltage input. A third object of the present invention is to provide an inverter device having a plurality of voltage input terminals and capable of correcting variations by individual voltage input terminals. In the inverter device according to the present invention, a converter for converting an AC voltage to a DC voltage is provided. A capacitor for smoothing a DC voltage, an inverter unit for converting the smoothed DC voltage to an AC voltage, first setting means for setting a frequency command value by an analog voltage, and a second setting means for setting a control parameter. Setting means;
Control means for individually converting a frequency command for a plurality of analog voltage set values inputted from the first setting means , wherein at least two or more of the first setting means are provided.
The resolution of the frequency command set by analog voltage
It can be set to . BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 of the Invention FIG. 1 is a block diagram of an inverter device according to an embodiment of the present invention. In the figure,
Reference numerals 51 to 53 and 55 to 58 are the same as those of the conventional device, and a description thereof will be omitted. Reference numeral 10 denotes an inverter device, and reference numeral 11 denotes control means for generating a signal for driving the inverter unit 53. FIG. 2 is a block diagram showing the inside of the control means of the inverter device according to one embodiment of the present invention.
In the figure, 55 to 57, 59, 60, and 64 to 66 are the same as those of the conventional device, and the description thereof is omitted. 11 is a control means for generating a signal for driving the inverter unit 53, 12 is a ROM storing a program for an operation to be executed by the microcomputer 59, and 13 is a RAM as a work area used when the microcomputer 59 executes the operation. , 14 are EEROMs for storing control parameters such as a frequency command conversion value for an analog voltage input value set by the parameter setting means 56. FIG. 3 is a flowchart of the filtering process of the inverter device according to one embodiment of the present invention. When performing a frequency command based on an analog voltage input value, noise affects the frequency command.However, the effect of this noise on the frequency command is greater when the output frequency is lower than when it is high. A time constant for the high-speed filter is previously stored in the EEPROM 14 as a time constant.
Two types of low-speed filter time constants are prepared, and filter processing is performed by switching between the two filter time constants according to the output frequency. When the filtering process is started, step S
In step S1, the current output frequency is read, and in step S2, it is determined whether the current output frequency is a high-speed area or a low-speed area. In the case of the high-speed region, the high-speed filter time constant is read from the EEROM 14 in step S3.
The low-speed filter time constant is read from M14. continue,
Filter processing is performed in step S5. The reference frequency for determining whether the region is the high-speed region or the low-speed region in step S2, the high-speed filter time constant read in step S3, and the low-speed filter time constant read in step S4 are the write signal from the parameter setting means 56. The microcomputer 59 receives the
And the setting value written in the RAM 13. By the way, in the above-described embodiment, when the filtering process is started (corresponding to step S53 in FIG. 11),
An example in which the high-speed filter time constant and the low-speed filter time constant are selectively used in the flowchart shown in FIG.
It is also possible to determine whether or not to execute the filter processing by the determination in step S2 in FIG. For example, step S
Assuming that the reference frequency for judging between the high-speed region and the low-speed region in 0 is 0 Hz, the high-speed filter time constant is always selected. If the high-speed filter time constant is set to 0, this corresponds to the operation without filtering. As described above, the setting of the reference frequency for judging the high-speed area or the low-speed area in step S2 and the setting of the high-speed filter time constant and the low-speed filter time constant allow the processing without the filter and the conventional filter. Processing, high-speed filtering, and low-speed filtering can be selected. Embodiment 2 of the Invention FIG. 4 is a flowchart for switching the frequency resolution by the external terminal of the inverter device according to one embodiment of the present invention, and FIG. 5 is switching the frequency resolution by the external terminal of the inverter device according to one embodiment of the present invention. FIG. 7 is a diagram showing a relationship between an analog voltage and a frequency command at the time. In FIG.
Reference numeral 21 denotes a straight line of a frequency command for an analog voltage in the normal mode, and reference numeral 22 denotes a straight line of a frequency command for the analog voltage in the simple positioning mode. The process of changing the frequency resolution by an external contact signal will be described with reference to FIGS. In step S11, the ON / OFF state of the external contact signal 66 is read, and in step S12, it is checked whether the simple positioning mode has been designated. If the simple positioning mode is not specified, the gain frequency by the straight line 21 of the normal mode in FIG. 5 is selected in step S13, and if the simple positioning mode is specified, the process proceeds to step S13.
At 14, the gain frequency by the straight line 22 in the simple positioning mode of FIG. 5 is selected. Here, the value of the frequency voltage gain in the normal mode in step S13 and the value of the frequency voltage gain in the simple positioning mode in step S14 are written in the EEPROM 12 and the RAM 13 by the microcomputer 59 in response to a write signal from the parameter setting means 56. Use the set value. Subsequently, the frequency command is changed in step S15. The calculation method of the frequency command for the analog voltage can be changed depending on the ON / OFF state of the external contact signal 66. Therefore, the method for calculating the frequency command for the analog voltage and for the analog voltage input in the simple positioning mode can be changed. Switching of the frequency resolution can be easily performed. Next, the operation method will be described. In the case of the normal speed control, the analog voltage command is converted into the frequency command in the same manner as the conventional mode in the normal mode. When the operator of the inverter attempts to perform the simple positioning control and designates the simple positioning mode by an external setting signal, the frequency command is switched from f1 to f2 even with the same analog voltage input VIN as shown in FIG. Can be decelerated to f2, the frequency resolution increases after the start of deceleration, and precise speed control becomes possible, so that simple positioning control by analog voltage input is facilitated. Embodiment 3 of the Invention FIG. 6 is a flowchart for calculating a frequency command from an analog voltage input value of the inverter device according to one embodiment of the present invention. FIG. FIG. 6 is a diagram showing a relationship between an input voltage and an output frequency when input voltage calibration is performed for each analog voltage input terminal. Embodiment 3 of the present invention is an inverter device having a plurality of analog voltage input means, in which the frequency resolution for each analog voltage input value is individually set. In FIG. 2, the microcomputer 59 receives a write signal from the parameter setting means 56 and receives the frequency setting voltage bias V set at the analog voltage input terminal 64.
a1 and the output frequency corresponding to the voltage bias set in the setting means 56 are stored in the EEPROM 14. Also,
An arbitrary frequency setting voltage gain set in the analog voltage input terminal 64 by the same operation and an output frequency corresponding to the gain value are stored in the EEPROM 14. Next, the frequency setting voltage bias Va2 and the frequency corresponding to the bias value, the frequency setting voltage gain and the frequency corresponding to the gain value are stored in the EEPROM 14 in the same manner. As described above, there are two types of linear functions of the frequency command with respect to the voltage input, the case of the frequency setting voltage bias Va1 and the case of the frequency setting voltage bias Va2. Next, the processing from the input of the analog voltage to the calculation of the frequency command will be described with reference to FIGS. The analog voltage input Va1 captured in step S21 is
A / D conversion is performed in step S22, and a frequency command f1 is calculated from the A / D conversion value in step S23. In step S24, the value of f1 is stored. Subsequently, the analog voltage input Va2 captured in step S25 is A / D converted in step S26, and the frequency command f2 is calculated from the A / D converted value in step S27. In step S28, the value of f2 is stored. Step S29
In step S24, the values f1 and S2 stored in step S24 are used.
The frequency f2 stored in step 8 is synthesized to generate a frequency command. Next, a method of operating the frequency command will be described. For example, if there are two analog voltage input terminals,
As shown in FIG. 7, one is a normal frequency command terminal,
One of them is assigned as a high-precision frequency command terminal.If the same accuracy as the conventional one is used, a command is sent using the frequency setting voltage bias by the normal frequency command terminal, and if you want to increase the resolution of the frequency command, Using the terminal and high-precision frequency command terminal together, first send a rough command with the frequency setting voltage bias by the normal frequency command terminal, and then fine-adjust the frequency command using the frequency setting voltage bias by the high-precision frequency command terminal I do. As described above, the input voltage calibration is performed for each terminal, and the frequency command for each voltage command is obtained according to the calibration value, whereby the frequency resolution of the terminal can be set individually. Since the present invention is configured as described above, it has the following effects. The input voltage is calibrated for each voltage input terminal , and the frequency command is obtained based on the calibration value. It can be set individually, and the variation of each voltage input terminal can be corrected. Furthermore, since the resolution of the frequency command of each voltage input terminal can be set arbitrarily, fine adjustment of the frequency command is possible.

BRIEF DESCRIPTION OF THE 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 a control unit 20 of the inverter device according to one embodiment of the present invention. FIG. 3 is a flowchart of a filter process of the inverter device according to the embodiment of the present invention; FIG. 4 is a flowchart for switching frequency resolution by an external terminal of the inverter device according to one embodiment of the present invention. FIG. 5 is a diagram showing a relationship between an analog voltage and a frequency command when frequency resolution is switched by an external terminal of the inverter device according to one embodiment of the present invention. FIG. 6 is a flowchart for calculating a frequency command from an analog voltage input of the inverter device according to one embodiment of the present invention. FIG. 7 is a diagram illustrating a relationship between an input voltage and an output frequency after voltage input calibration is performed for each of a plurality of analog voltage input terminals of the inverter device according to the embodiment of the present invention; FIG. 8 is a block diagram of a conventional inverter device. FIG. 9 is a block diagram showing the inside of the control unit 4. FIG. 10 is a diagram illustrating a relationship between an output voltage and an input voltage after voltage input calibration. FIG. 11 is a flowchart of conversion to a frequency command of a conventional inverter device. [Description of Signs] 10 inverter device, 11 control means, 12 R
OM, 13 RAM, 14 EEPROM, 21
Linear frequency command for analog voltage in normal mode, linear frequency command for analog voltage in simple positioning mode, 50 inverter unit, 51 converter unit, 52 smoothing capacitor,
53 Inverter part, 54 Control means, 55 PW
M signal, 56 parameter setting means, 57 input interface, 58 induction motor, 59 microcomputer,
60 PWM signal creation means, 61 ROM, 6
2RAM, 63 EEROM, 64 analog voltage input terminal, 65 A / D converter, 66 external contact signal input means.

Continuation of the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628-7/632 H02P 21/00 H02M 7/42-7/98 H03H 11 / 00-11/54 G06F 3/05 H03M 1/00-1/88

Claims (1)

(57) [Claim 1] A converter unit for converting an AC voltage to a DC voltage, a smoothing capacitor for smoothing the DC voltage, an inverter unit for converting the smoothed DC voltage to an AC voltage, At least two or more frequency command values set by analog voltage
First setting means, the second setting means, said first control means for converting separately the frequency command to a plurality of analog voltage setting value input from the setting means for setting parameters for the control of When, with the analog electric in at least two of said first setting means
The resolution of the frequency command set by the pressure can be set arbitrarily
An inverter device characterized in that: