JPH0374176A - Pwm waveform outputting method - Google Patents

Abstract

PURPOSE:To reduce memory capacity by reading out basic data with interval corresponding to the target frequency of load, setting the time data in the real timer in a microcomputer every half period of carrier wave, then inverting the output and producing a PWM waveform necessary for inverter control of the load. CONSTITUTION:An inverter comprises a control section (microcomputer) 10, a first memory 12a for storing basic data concerning to the amplitude of a sinusoidal wave at equally divided positions, a second memory 12b for storing time data, a third memory 12c for storing step data, and a fourth memory 12d for storing voltage data. A timer is reset and started with rising or falling timing of a PWM timer and the output from a real time I/O port is inverted by means of a real timer. By such arrangement, memory capacity can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a pH control system used for inverter control of a load (for example, a compressor such as an air conditioner). H (plus width)
The present invention relates to a waveform output method (thmodulation), and more specifically to a PvM waveform output method that reduces the pulse width of a phase-to-phase voltage waveform with respect to a load and suppresses load noise.

[Conventional example] In recent years, inverter control devices have come to be used not only in air conditioners but also in various home appliances.

Here, to explain an air conditioner as an example, as shown in FIG. part 2, a memory part 3 that stores various waveform data corresponding to the operating frequency of the compressor 1, such as time data and switch data for 60 electrical degrees (or 30 degrees), and a memory part 3 that stores various waveform data corresponding to the operating frequency of the compressor 1, and A control unit (cpu
; a microcomputer) 4, and a base drive unit 5 that drives the plurality of transistors according to control signals thereof.

Then, when a command for a predetermined operating frequency is output in accordance with the operation of a remote control, panel, etc., waveform data for 60 electrical degrees corresponding to the operating frequency command is read out from the memory section 3, and these waveform data are PWM of compressor 1 based on
A waveform (pulse signal) is obtained. At this time, as shown in FIG. 14, in the case of the time data storage control method, the waveform data is U-phase, V-phase, V-phase sine waves 6, 7, .
8 and the carrier waveform 9 to the next intersection (time data), and data on the magnitude of the carrier waveform 9 and the sine wave 6 during that time (switch data). In this case, for example, as shown in FIG.
For example, in section A, 50 μs time data and “0
The switch data of "011/O" is obtained, and in section B, the time data of 64 μs and the switch data of "/O/O/O" are obtained.
“X+y*Z” is the inversion of “u, v, w”.

Therefore, the memory section 3 stores time data and switch data "u" corresponding to the operating frequency of the compressor 1 in advance.
, v, w" are stored. Also, the time data and switch data are repeatedly read out from the memory,
Basic waveform pattern for 60 degrees based on those waveform data (
PWM waveform) is repeated to obtain a one-period pattern (approximate sine wave).

To explain in more detail, the power and
Turn on each transistor in transistor section 2.

A signal to turn off is output for a predetermined period of time by the control unit 4, but
First, the I/O port 1' (UpVpLX
pY*2) outputs a signal of "0011/O" for a period of 50 μs. Furthermore, the primary I/O port (UpV
*I'tXtY*Z) for a time of 64 μs "/O/
O/O" signal is output. Similarly, the I/O" signal is output.
A signal combining 1"00" is output from the port (UyVy'yX+yyZ) during the time data period. That is, from the I/O port,
A pulse train of the Q It signal is output, and these pulse trains are input to the base drive unit 5. Then.

Each transistor of the power transistor section 2 is driven by this base drive section 5, and the output (U
, V, W) is applied to the compressor. Due to these pulsed voltages, υ-v, v-w, w-u interphase voltage waveforms are applied to the compressor ■, so an approximate sine wave current flows through the compressor 1. The motor is driven.

[Problems to be Solved by the Invention] However, in the PwM waveform output of the inverter control device, since the voltage/operating frequency (V/F) of the load is controlled constant, the data for obtaining the PWM waveform is requires an electrical angle of 30 or 60 degrees, and the amount of data required to make the load operating frequency extremely fine is enormous. Furthermore, the carrier frequency is also restricted, and the time data stored in the memory section 3 cannot be stored in the microcomputer. There was a problem that the processing speed could not be set to a value smaller than the processing speed (several μs). In other words, the signal (UyVJyXy3'tZ) output from the I/O boat cannot be applied to the compressor 1 in a phase-to-phase voltage waveform of about several μs;
For example, the distortion of the current waveform of the compressor 1 becomes large, and the variation of the operating frequency when the compressor 1 is driven causes a step sound to be generated.

Therefore, it is conceivable to use a high-speed processing microcomputer or gate array circuit as the control unit 4.
At present, the problem is that the cost is high.

This invention was made in view of the above problems.

The purpose of this is to reduce the memory capacity required to store the data used to obtain the PWS waveform, and also to provide PWM waveform output that allows for finer variation of the operating frequency and suppresses the gradual noise caused by the load. The purpose is to provide a method.

[Means for Solving the Problems] In order to achieve the above object, the inverter control device of the present invention divides a predetermined sine wave into equal parts, and uses the height value of the fundamental wave at the positions of the equal division as fundamental wave data. , and 0 degrees to 60 degrees, 60 degrees to 120 degrees, and 120 degrees of the sine wave.
a first memory that stores fundamental wave data from 180 degrees to 180 degrees; and a carrier wave of a constant frequency is superimposed on the sine wave, and corresponds to the height value of the fundamental wave data from the peak or trough of the carrier wave. a second memory that stores time data of the interval to a predetermined position of the carrier wave to be read, and a third memory that stores data of the interval for reading the fundamental wave data of the first memory according to the target frequency of the load. and a fourth memory for storing data of the output voltage corresponding to the target frequency, and the frequency range is from 0 degrees to 60 degrees and 60 degrees based on the reading interval data corresponding to the target frequency of the load.
Read fundamental wave data from 120 degrees and from 120 degrees to 180 degrees.

The time data of the second memory is obtained from the fundamental wave data and the voltage data, and these time data are set in the real timer of the microcomputer every half period of the carrier wave, and the real timer of the microcomputer is set to the time data of the second memory. The gist is that the output of the I/O port is inverted controlled using the above time data to obtain U-phase, V-phase and S-phase PVM waveforms for inverter control of the load.

[Function] With the above configuration, the predetermined fundamental wave data of the first memory is read out in accordance with the operating frequency command of the load, and the predetermined time data of the second memory is read out based on these fundamental wave data. Moreover, the time data is set in the real timer of the microcomputer every half period of the carrier wave. Furthermore, the reading interval data (step data) of the third memory is changed depending on the operating frequency of the load, and the fundamental wave data read from the first memory is changed, so the time data read from the second memory is changed. Differently, this time data is set in a real timer. Moreover, the time data for the U phase, V phase, and the other phase are each set in the real timer, and several pieces of time data are sequentially read out using the reading interval data of the third memory and the fundamental wave data based on this interval data. and is set in the real timer every half period of the carrier wave.

Then, the output of the real-time I/O port is inverted controlled at the time corresponding to the set time data, so the I/O
The PIIM waveform for driving the load at the above operating frequency is output from the /O port, and the U-phase and V-phase are and PW for V phase
M waveform is output. In this way, the PG
An M waveform can be obtained, and the PIIIN waveform allows an interphase voltage waveform of several μs to be applied to the load.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. Note that in FIG. 1, the same parts as in FIG. 13 are given the same reference numerals, and redundant explanation will be omitted.

In FIGS. 1 to 8, the inverter control device includes:
Control unit with real-time and its I/O ports (
cpu (microcomputer)/O and a predetermined sine wave 1
1 is divided into equal parts (for example, the 60 degree sine wave is divided into 256 equal parts), the height value of the sine wave 11 obtained at this equal division position is taken as the fundamental wave data, and in the same way from 60 degrees to 120 degrees. A first memory 12a stores the height values of the sine wave 11 obtained at equal division positions from 120 degrees to 180 degrees as a fundamental wave, and a carrier wave 13 of a constant frequency is superimposed on the sine wave 11. , the interval from the peak or valley point of this carrier wave 13 to the position of the height value of the sine wave 11 resulting from the above-mentioned equal division is defined as time data 1. A second memory 12b that stores step data as II, a third memory 12c that stores step data for reading out the fundamental wave data according to the target operating frequency, and a third memory 12c that stores step data for reading out the fundamental wave data according to the target operating frequency, and The memory unit 12 includes a fourth memory 12d that stores voltage data to be multiplied by the fundamental wave data read by the step data. In FIG. 2, the fundamental wave data is an average value in equal division, but it may be a value at one end of the equal division. In addition, in FIGS. 2 to 4, the peak value H of the sine wave 11 is 256, the carrier frequency fc is 3°3 kl (z, and the maximum value of the control rate is 256.
The data is for the case.

Here, with reference to FIGS. 2 to 8, the data stored in the first to fourth memories and the method of calculating time data I and (2) using this data will be explained.

First, as shown in FIG. 2, for example, the peak value (H=2
56) 60 degrees of the sine wave 11 is divided into 256 equal parts, and the height (Ha) of the sine wave 11 in this equal division is Ha = 2
55 sin (calculated by J, and this calculated value is used as fundamental wave data.Furthermore, in the same manner as above, 6 of sine wave 11
0 degrees to 120 degrees and 120 degrees to 180 degrees are also divided into 256 equal parts, the height of the sine wave 11 in these equal divisions is calculated, and this calculated value is used as the fundamental wave data (5th (shown in figure). In addition, as shown in FIGS. 3 and 4, the interval (time) from the peak of carrier wave 2 with a negative slope to the intersection of the carrier wave 13 and the fundamental wave data is defined as time data I, and the interval (time) with a positive slope The interval (time) from the trough of the carrier wave 13 to the intersection of the carrier wave 13 and the fundamental wave data is defined as time data ■ (shown in FIG. 6). Furthermore, in order to repeatedly read the fundamental wave data of the first memory 12a according to the operating frequency, read interval data is calculated. For example, if it is 157, the third fundamental wave data from the beginning (3, 222 or 220), this third to fourth fundamental wave data (7, 224 or 217), this fourth to third fundamental wave data, this third to fourth fundamental wave data, and this Interval data "3, 4, 3, 4.3" for repeatedly reading out the fourth to third fundamental wave data is calculated (as shown in FIG. 7). In order to obtain the time data I or ■ using the read fundamental wave data, the fundamental wave data is multiplied by predetermined voltage data, and the voltage data for obtaining the time data I or ■ from the calculated value obtained as a result. is calculated (shown in FIG. 8). Note that the second memory 12
b, the above calculated value is time data 1. II (shown in FIG. 6).

Next, the operation of the above-mentioned inverter control device is shown in FIGS. 9 to 1.
This will be explained based on the flowchart shown in FIG. 1 and the time chart shown in FIG. 12.

First, assuming that the operating frequency command of the compressor 1 is issued at, for example, 15 Hz, the PVM timer in the control unit/O is set for a predetermined period of time 1, for example, 2/f c (41501 Js).
(Step 5TI), its PII
The M timer operates repeatedly at 150 μs (see Figure 12 (
(shown in a)). Then, it is determined whether the timer time of the PVM timer has elapsed, that is, it is the rising or falling timing of the PIIIM timer (step 5).
T2), if the timer time has not elapsed, it is determined whether or not the operating frequency is changed (step 5T3); if there is no change in the operating frequency, the process returns to step ST2, and the above-mentioned Steps are repeated.

When the above operating frequency has changed, for example, when the previous operating frequency was changed from 16 Hz to 15 Hz, frequency data setting processing is performed (step 5T4), and in this case, since the operating frequency is 15 Hz, The reading interval data 5n (Sl to SS) is "3.4.4."

3.4” is changed to “3, 4, 3, 4.3”, and this “3, 4, 3, 4.3” is read and set (
Step 5TIO), furthermore, "17" of the voltage data (V) corresponding to the 15th operating frequency is read out and set (Step 5TII), and again in Step ST2.
Return to and repeat the above steps.

Subsequently, in step ST2, when the timer time of the Pli1M timer elapses, that is, when the 1wM timer rises or falls, an interrupt is generated to set the waveform data, and the timer 1 is reset and started ( Step 3T20), and the already obtained time data is set in the real timer (step 5T21). Note that the real-time setting is performed for the U phase, V phase, and V phase, respectively.

Next, the next time data, for example, the U phase, will be explained. When the already obtained time data is I, a process is performed to obtain time data ■. If the time data I set in the real timer is based on the read interval data S1 "3", then No=No+S, =3+ due to the next interval data S, IJ4 #j
4=7 is calculated (step 5T22), and this No=7
The fundamental wave data corresponding to is read out and set (
Step 5T23), and further.

The fundamental wave data is multiplied by the voltage data "'17", but when the maximum control rate of the compressor 1 is 2, 0.
In order to obtain a control rate with an accuracy of 01, /O0 times, that is, the control rate 2 becomes voltage data "200", and the voltage data is
Since 17 u indicates a control rate of 0.17, the calculation of fundamental wave data x 177200 is performed, and the predetermined calculated value shown in FIG. 6 is obtained (step 5T24). Then, the time data corresponding to the calculated value is For example, you can get the previous time data! In this case, the time data corresponding to the current calculated value is transferred from the first memory 12b to the RAM.
(internal memory). Furthermore, although we have explained the U phase, based on the fundamental wave data from 0 degrees to 60 degrees, 60 degrees to 120 degrees, and 120 degrees to 180 degrees shown in Fig. When the time data corresponding to is set from the second memory 12b to V, V of the RAM, the process returns to step ST3 and the above steps are repeated. On the other hand, when the time of timer 1 reaches the value set in the real timer, the real timer inverts the output of the real time I/O port (as shown in FIG. 12(b)). In addition, the reversal control is performed for the U phase and
This is done for the V phase and the S phase.

Subsequently, in the above step ST2, when the timer time of the PIi1M timer elapses, an interrupt is generated to set the waveform data again, the timer 1 is reset and started, and in the above step 5T25, υ, V of the RAM are
, W are respectively set in the real timer. Furthermore, processing for obtaining the next time data is performed in the same manner as described above, and the process returns to step ST3. On the other hand, when the time of the timer 1 reaches the value set in the real timer for the U phase, the real timer inverts the output of the real time I/O boat (as shown in FIG. 12(b)). Note that the inversion control is performed for the υ phase, the V phase, and the V phase, respectively, as described above.

In addition, the inversion of the real-time I/O boat output (U-phase, V-phase, and S-phase PWM waveform output) is
By obtaining the phase PVM waveform, the U of '1"80"
Phase, ■ phase, l11 phase, X phase, y phase, and two-phase PVM waveforms are obtained, and these pulse trains are input to the base drive unit 5. Then, each transistor of the power transistor section 2 is driven by the base drive section 5, and a pulse-like voltage waveform corresponding to the above-mentioned PWM waveform is applied to the compressor 1. .

V-xi, w-v interphase voltage waveforms are applied, an approximate sinusoidal current flows through the compressor 1, and the motor of the compressor 1 is driven.

In this way, the memory unit 12 stores one fundamental wave data based on the predetermined sine wave 11 and a carrier wave 1 with a constant frequency.
3 and the time data I and ■ based on the fundamental wave data, and to obtain the time data corresponding to the operating frequency,
Step data (reading interval data) for reading the fundamental wave data and voltage data corresponding to the operating frequency are provided, and time data corresponding to the operating frequency of the compressor 1 can be obtained using these data.
2, and the carrier frequency remains constant as the operating frequency changes. Therefore, when controlling the compressor 1 with an inverter, the interphase voltage waveform applied to the compressor 1 can be made into a pulse of several microseconds, and the current waveform of the compressor 1 becomes closer to a sine wave (that is, the current waveform of the compressor 1 becomes more similar to a sine wave). distortion is reduced), harmonic components included in the current waveform are reduced, and noise from the compressor 1 is suppressed.

[Effects of the Invention] As explained above, according to the PvM waveform output method of the present invention, a predetermined sine wave is equally divided, and fundamental wave data at the equally divided positions and a constant frequency carrier wave are added to the sine wave. and reads the fundamental wave data according to the interval data (switching data; time data) from the peak or trough of this carrier wave to the position corresponding to the fundamental wave data and the operating frequency of the load (compressor). Interval data and output voltage data for the above operating frequency are provided, and calculation processing is performed using the fundamental wave data and output voltage data corresponding to the reading interval data corresponding to the operating frequency of the compressor, and the The time data was set to real time, and the output waveform of the real-time I/O port was set to PVM waveform.

The amount of data required to obtain the PVM waveform is small, the memory capacity is small, the carrier frequency can be kept constant even when the operating frequency is varied, and the pulse width of several μs can be achieved in the phase-to-phase voltage waveform applied to the compressor. This reduces the distortion of the compressor current waveform, and
Moreover, it is possible to reduce harmonic components included in the current waveform and suppress the noise of the compressor.

[Brief explanation of drawings]

Fig. 4 shows one embodiment of the present invention, and is a schematic block diagram of an inverter control device to which a PGM waveform is applied, and Figs. 2 to 4 are for explaining data calculation used in the above-mentioned PWM waveform output method. Figures 5 to 8 are from P above.
Figures 9 to 11 and 12, which are diagrams for explaining the contents of the memory used in the WM waveform output method, are shown in the above P.
A flowchart and a time chart for explaining the VM waveform output method, FIG. 13 is a schematic block diagram of a conventional inverter control device, and FIG. 14 is data used in the PVM waveform output method of the conventional inverter control device. FIG. 15 is a diagram for explaining the contents of a memory used in a conventional PVM waveform output method of an inverter control device. In the figure, 1 is a compressor (load), 2 is a power transistor section (several switching elements), 5 is a base drive section, /
O is a control unit (CPU: microcomputer). 11 is a sine wave, 12 is a memory section, 12a is the I-th memory (fundamental wave data), 12b is the second memory (time data), 12c is the third memory (reading interval data), 12d is the fourth memory memory (output voltage data), 13 is a carrier waveform. Figure 1

Claims (1)

[Claims] (1) A predetermined sine wave is equally divided, the height value of the fundamental wave at the equally divided position is used as fundamental wave data, and from 0 degrees to 60 degrees, from 60 degrees to 120 degrees, and from 120 degrees a first memory that stores fundamental wave data at 180 degrees; and a carrier wave that superimposes a carrier wave of a constant frequency on the sine wave and that corresponds to the height value of the fundamental wave data from the peak or trough of the carrier wave. a second memory that stores time data of an interval to a predetermined position of the wave; a third memory that stores data of an interval for reading the fundamental wave data of the first memory according to a target frequency of the load; and a fourth memory that stores output voltage data corresponding to the target frequency, and the output voltage is adjusted from 0 degrees to 60 degrees, from 60 degrees to 120 degrees, and from 120 degrees based on reading interval data corresponding to the target frequency of the load. read out fundamental wave data at 180 degrees from 180 degrees, obtain time data in the second memory using the fundamental wave data and the voltage data, and transfer these time data to the microcomputer real time every half period of the carrier wave. A U-phase and V
A PWM waveform output method characterized in that PWM waveforms of phase and W phase are obtained.