JPH0797908B2 - Sine wave PWM signal generator - Google Patents

Description

The present invention relates to an inverter device, and more particularly to a sine wave PWM signal generator for an inverter that applies a one-chip microcomputer.

[Conventional technology]

Figure 4 shows, for example, "AC servomotor and microcomputer control".
(February 1984) Published by Sogo Electronics Co., Ltd.) FIG. 6 is a block diagram of an internal microcomputer of the sine wave PWM signal generation by the microcomputer shown in Chapter 6. In the above-mentioned document, the software timer is used, but in the conventional example, an interval timer that is actually suitable is used. Figure 5 shows PWM
FIG. 6 is a flow chart of the interrupt processing for occurrence, and FIG. 6 is a flow chart of the main processing.

In FIG. 4, 101 is a CPU, 102 is a timer, 103 is a RAM for storing correction values, and 104 is waveform generation data (port output data + time data) created by a computer such as a personal computer.
A ROM storing a table, 105 is a waveform data pointer, and 106 is a port for outputting a PWM signal.

Next, the operation will be described with reference to FIGS. 4, 5, and 6.

As shown in the flow chart of FIG. 5, when an interrupt request is issued by the timer 102, the timer interrupt is entered, the address pointer 105 of the table of the ROM 104 is incremented (501), and if the address pointer 105 is the table end, the address pointer 105 is set. Initialize (502, 503), import the data from the table to the CPU 101, and port the output data to the port.
Output to 106 (504) and if the port output is zero voltage,
The correction value stored in the RAM 103 is added to the time data (505, 506). Next, the time data until the next interrupt is set in the timer 102 (507), and the interrupt processing is exited.

After that, an interrupt occurs at the timing of the time data of the waveform generation data stored in the table in ROM 104, and 501 to 507
The operation of is repeated and the PWM signal is generated. Next, when changing the frequency, it is judged whether the correction value is within the correction limit as shown in FIG. 6 (602).
Change the correction value in RAM103 added in 06. If the correction value exceeds the limit, change the table in ROM 104.

[Problems to be solved by the invention]

Since the conventional sinusoidal PWM signal generator is configured as described above, as shown in FIG. 7, since the base waveform generation data is corrected to lower the frequency and simultaneously lower the voltage, There is a drawback that the relationship between the voltage and the frequency cannot be set independently and is uniquely determined, and it is necessary to have many tables in the ROM, which increases the ROM capacity.

The present invention has been made to solve the above problems, and an object thereof is to obtain a sinusoidal PWM signal generator capable of arbitrarily setting the voltage and frequency with a small ROM capacity.

[Means for solving problems]

The sine wave PWM signal generator of the present invention has a plurality of tables in RAM in which waveform generation data consisting of port output data and time data are sequentially arranged, and also has waveform data such as reference sine wave data in ROM. , PWM signal is generated by timer interrupt processing using one table, and in parallel, waveform generation data is created in other table of RAM based on the waveform data on the ROM and frequency and voltage command by main processing. After the creation, the table selected in the interrupt process is switched, and the frequency and the voltage are sequentially switched.

[Action]

The sine wave PWM signal generator according to the present invention creates waveform generation data in a microcomputer, which was previously created in a personal computer, etc. and written in ROM, and writes it in RAM, and generates a PWM signal based on that data. It was made to let.

Example of Invention

 An embodiment of the present invention will be described in detail below.

FIG. 1 is an internal block diagram of a microcomputer which is a computer showing an embodiment of the present invention. In the figure, 101 is a CPU, 102 is a timer, 103 is a RAM that stores waveform generation data, 104 is a ROM that stores a waveform data table such as reference sine wave data, and 105 is a waveform generation data address in the waveform generation data table. Is an address pointer, and 106 is a port for outputting a PWM signal.

In FIG. 1, the part drawn with a solid line shows the flow of interrupt processing for generating a PWM signal, and the part with a dotted line shows the flow of main processing for creating waveform generation data.

Next, the operation will be described.

A flowchart of the main process is shown in FIGS. 3a and 3b.

First, in the main processing, it is determined in 301 whether or not there is a change in frequency and voltage, and if there is a change, the process goes to the data creation program in 302. In the data creation program, the one not used in interrupt processing is selected as the output of the created data (303).

Next, from the frequency data, voltage data, carrier frequency data, and ROM 104, waveform generation data for 30 ° is created from the waveform data by the conventional triangular wave comparison method (30
Four).

Next, develop from 30 ° data to 60 ° (30
5) Furthermore, at 306, the data that is short in time (it does not affect the processing of the microcomputer) is cut. When data creation is completed, a flag indicating that table switching is possible is set (307) and the main loop is executed.

On the other hand, in the interrupt processing shown in the flowchart of FIG.
When the interrupt process is started by the timer 102, the address pointer 105 is incremented (201) and it is determined whether it is the table end (202). If it is the table end, it is determined whether there is a table switching request (20
3) If there is a request, switch the table (204). Next, the address pointer 105 is initialized.

Further, the contents of the table on the RAM 103 indicated by the address pointer 105 are fetched into the CPU, the point output data is output to the port 106 (206), and the time data is transferred to the timer 10.
Set to 2 and exit from interrupt processing. After that, interrupt processing is started at the timing according to the time data of the waveform generation data, and the PWM signal is generated.

According to one embodiment of the present invention, a plurality of waveform generation data tables are provided on the RAM, waveform generation data created in a personal computer or the like and written in the ROM is created in the microcomputer, and written in the RAM. By generating the PWM signal based on the data, it is not necessary to have a lot of data in the ROM, and since the waveform generation data is created from the voltage and frequency data, there is no need to add zero voltage correction.
Moreover, as shown in FIG. 8, there is an effect that the voltage and frequency can be set arbitrarily.

〔The invention's effect〕

As described above, according to the present invention, since the waveform generation data is stored in the RAM, it is not necessary to have much data in the ROM, and since the waveform generation data is created from the voltage and frequency data, the zero voltage There is no need to add
Moreover, there is an effect that a device capable of arbitrarily setting the voltage and the frequency can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a microcomputer section showing an embodiment of the present invention, FIGS. 2, 3a, and 3b are flow charts showing an embodiment of the present invention, and FIG. 4 is an internal block diagram of a conventional microcomputer. 5 and 6 are conventional flowcharts,
FIG. 7 is an explanatory diagram of a conventional voltage / frequency pattern, and FIG. 8 is an explanatory diagram of a voltage / frequency pattern according to an embodiment of the invention. In the figure, 101 is a CPU, 102 is a timer, 103 is RAM, 104 is ROM, 1
05 is an address pointer and 106 is a boat. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A sine wave PWM signal generator using a computer, which has a RAM having a plurality of tables for sequentially arranging waveform generation data consisting of port output data and time data, and waveform data such as reference sine wave data. A ROM and one table on the RAM are used to generate a PWM signal by a timer interrupt process, and in parallel, another table of the RAM based on waveform data and frequency on the ROM and a voltage command by the main process. A sine wave PWM signal generator characterized in that it further comprises control means for sequentially generating waveform generation data, switching a table to be selected in an interrupt process after creation, and arbitrarily setting a frequency and a voltage.