JPH0787699B2 - Inverter control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inverter control device used for controlling a load (for example, a compressor such as an air conditioner), and more specifically, to increase the resolution of an inverter frequency, The present invention relates to an inverter control device in which changes in operating frequency are made extremely fine.

[Conventional example] In recent years, this type of inverter control device has come to be used not only in air conditioners but also in various home appliances.

Here, taking an air conditioner as an example, as shown in FIG. 11, the inverter control device includes a power transistor including a plurality of switching elements (transistors) for driving the compressor (load) 1. Waveform data corresponding to the operating frequency of the section 2 and the compressor 1, for example, electrical angle
A memory unit 3 that stores various time tables and switch data for 60 degrees (or 30 degrees), and a predetermined waveform data is read from the memory according to a command of the operating frequency, and the plurality of switchings are performed based on the waveform data. A control unit (CPU; microcomputer) 4 for controlling ON / OFF of the elements for a predetermined time, and a base drive unit 5 for driving the plurality of transistors by the control signal thereof are provided.

Then, when a command for a predetermined operating frequency is output according to the operation of the remote controller or the panel, the waveform data for an electrical angle of 60 degrees corresponding to the operating frequency command is read out from the memory unit 3, and these waveform data are stored. Based on this, a PWM waveform ((pluse width modulation) pulse signal) of the compressor 1 is obtained.At this time, as shown in Fig. 12, when the waveform data is the time data storage control method, the U phase is used. , V
Data (time data) of the interval from the intersection of the sine waves 6, 7 and 8 of the W and W phases and the carrier waveform 9 to the next intersection, and the large and small data of the carrier waveform 9 and the sine wave 6 between them (switch data) ) And. In this case, for example, as shown in FIG. 13, in the section A, time data of 50 μs and switch data of “001110” are obtained,
In section B, time data of 64 μs and switch data of “101010” are obtained. The "x, y, z" of the switch data is the inversion of "U, V, W". Therefore, the memory unit 3 stores the time data and the switch data "U, V, W" corresponding to the operating frequency of the compressor 1 in advance. Further, the time data and the switch data are repeatedly read from the memory, the basic waveform pattern (PWM waveform) for 60 degrees by these waveform data is repeated, and a one-cycle pattern (approximate sine wave) is obtained.

To explain in more detail, the power
A signal for turning on / off each transistor of the transistor unit 2 is output for a predetermined time by the control unit 4, but first from the I / O port (U, V, W, x, y, z) of the control unit 4. The signal "001110" is output for 50 μs. Further, the signal "101010" is then output from the I / O ports (U, V, W, x, y, z) for a time of 64 μs. Similarly, the I / O ports (U, V, W, x,
From y, z), a signal combining "1" and "0" is output during the time of the time data. That is, pulse trains of these “1” and “0” signals are output from the I / O port, and these pulse trains are input to the base drive unit 5. Then, each transistor of the power transistor unit 2 is driven by the base driving unit 5, and a pulsed voltage waveform corresponding to the output (U, V, W) of the I / O port is applied to the compressor 1. It Due to the pulsed voltages, the compressor 1 has UV, VW, WU
Since the phase-to-phase voltage waveform is applied, an approximate sine wave current flows in the compressor 1 and the motor of the compressor 1 is driven.

[Problems to be Solved by the Invention] However, in the above inverter control device, since the voltage / operating frequency (V / F) of the load is controlled to be constant, the data for obtaining the PWM waveform has an electrical angle of 30 However, there is a problem in that the amount of data becomes enormous and the memory capacity increases if the resolution of the inverter frequency is increased and the change of the operating frequency is made extremely fine.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to increase the resolution of the inverter frequency without increasing the memory capacity and to change the operating frequency extremely finely. To provide.

[Means for Solving the Problem] In order to achieve the above object, the present invention reads waveform data corresponding to a target frequency of the load from a memory when controlling the load by an inverter, and PWM based on the waveform data. In an inverter controller that obtains a waveform, drives a switching transistor ON / OFF by the PWM waveform, and outputs a voltage waveform to be applied to the load, a predetermined sine wave for an electrical angle of 60 degrees, 120 degrees, or 180 degrees. For the current division, and the first memory for storing the value of the height of the sine wave at the corresponding division position as the fundamental wave data, and the fundamental wave data corresponding to the operating frequency of the load is read from the first memory. A second memo that stores a plurality of step data specifying a data reading interval in the order of increase and decrease of its own address And,
A third memory for storing voltage data for adjusting the voltage of the output waveform by multiplying the fundamental wave data, and a position corresponding to each height of the carrier wave from a peak or a valley of the carrier wave of a constant frequency. And a fourth memory for storing the time interval up to the time interval as time data, and when the operating frequency of the load is set, a predetermined address of the second memory corresponding to the operating frequency is constantly provided over a fixed address range between them. Temporary storage means for temporarily storing a fixed number of each step data, and the second memory when the operating frequency is changed and until the changed operating frequency is reached from the current operating frequency. While shifting the address by 1 address at a time, a fixed number of each step data is read out over a constant address range and the The fundamental wave data is read out based on each step data stored in the storage means, the fundamental wave data is multiplied by the voltage data of the third memory, and the time data corresponding to the calculated value is obtained. A real timer I / O port according to a set value of the internal real timer, the control means repeatedly performing control for reading from the fourth memory and setting the internal real timer every half cycle of the carrier wave. It is characterized in that the PWM waveform is obtained by inversion control of the output of.

[Operation] With the above configuration, when the load (for example, the compressor) is controlled by the inverter, the temporary storage means (internal memory RA) is used.
A fixed number (for example, 20) of step data stored in M) are sequentially read. The fundamental wave data is read based on the step data, and the fundamental wave data is multiplied by the voltage data corresponding to the operating frequency of the compressor. Further, the time data corresponding to the calculated value by the multiplication result is read from the fourth memory and set in the real timer, and the real timer set is the timer time of the PWM timer (half cycle of carrier wave). It is done every time. That is, real timer I / O
Since the output of the port is inverted when the time data has elapsed from the start of the PWM timer, the PWM waveform corresponding to the operating frequency of the compressor is output from the real timer I / O port from the fixed number of step data. Is output.

Here, when the operating frequency is changed, the contents of the temporary storage means are rewritten. This rewriting is performed while shifting the address of the second memory by one address, so that the temporary storage means is rewritten. From the address shifted by one address, a fixed number of each step data is always stored over a fixed address range. Then, when a predetermined number of step data corresponding to the changed frequency is stored in the temporary storage means,
The rewriting of the fixed storage means is stopped. In this way, since a fixed number of step data are stored in the temporary storage means, the PWM waveform corresponding to the step data is output from the real timer I / O port as described above. Therefore, since it is not necessary to increase various data for obtaining the PWM waveform, the memory capacity can be reduced, and
The resolution of the operating frequency is increased, and the frequency can be changed smoothly.

[Examples] Examples of the present invention will be described below with reference to FIGS. 1 to 10. Incidentally, in FIG. 1, the same parts as those in FIG.

1 to 8, the inverter control device includes:
Control unit with real timer and its I / O port (CP
U; a microcomputer) 10 is further provided, and the predetermined sine wave 11 is divided into 60 electrical degrees, 120 electrical degrees, or 180 electrical degrees (for example, the electrical angle of the sine wave is defined as 225th electrical division), The first value stored as the fundamental wave data (shown in FIG. 3) in the height value of the sine wave 11 obtained at this equal division position
Memory 12a, a second memory 12b for storing the step data (shown in FIG. 4) for reading the fundamental wave data according to the operating frequency of the load, and the fundamental wave data read by the step data are multiplied. Voltage data (5th
(Shown in the figure) for storing a third memory 12c and the sine wave 1
1 is superimposed with a carrier wave 13 of a constant frequency, and the sine wave
The interval up to the position of the height value of time data I, II (8th
Memory unit 12 having a fourth memory 12d (shown in the figure). In addition, the control unit 10
Is an internal memory RAM that stores a certain number of step data in the second memory 12b when controlling the load inverter.
(Temporary storage means) 10a and step data of the internal memory RAM 10a are sequentially read out, the fundamental wave data is read out based on the step data, and the fundamental wave data and the voltage data are multiplied to obtain this calculation. It has a function of setting the above-mentioned time data corresponding to the value in the above-mentioned real timer at a constant time, for example, every half cycle time of the carrier wave (time of PWM timer).

Note that, in FIGS. 2 and 3, 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, the fundamental wave data is such that the peak value H of the sine wave 11 is 255 and the carrier frequency f
It is a value when c is 3.3 kHz and the control rate is 2.

Data stored in the first to fourth memories 12a, 12b, 12c and 12d will be described with reference to FIGS. 2 to 8.

First, as shown in FIG. 2, 60 degrees of the sine wave 11 having a peak value (H = 256) is equally divided into 255, and the height (Ha) of the sine wave 11 in this even division is calculated by Ha = 255sin θ. Then, the calculated value is used as the fundamental wave data. Also, in the same manner as above, at 60 degrees to 120 degrees and 120 degrees to 180 degrees of the sine wave 11,
Equally divide each into 255, and sine wave 1 in this equal division
The height of 1 is calculated, and the calculated value is used as basic data (shown in FIG. 3).

Further, as shown in FIG. 4, the step data has a larger value as the operating frequency of the load becomes higher. That is, in this embodiment, the step data is set to a larger value as the address of the memory 12b increases. Here, when controlling the compressor 1 at a certain operating frequency, a certain number (for example, 20) of step data is provided from the second memory 12b over a certain address range starting from an address corresponding to the above operating frequency. Are read out and stored in the internal memory (temporary storage means) RAM 10a. Then, the desired operating frequency is obtained by sequentially reading the reference wave data according to the step data stored in the internal memory. As is apparent from FIG. 4, the operating frequency is changed by changing the start address when reading the step data from the second memory 12b.
In addition, how much the operating frequency can be changed is
Since it is determined by the change rate of the step data stored in the second memory 12b, it is possible to improve the resolution of the operating frequency by appropriately setting the change rate.

Further, as shown in FIG. 5, the voltage data has a function of adjusting the voltage of the output waveform, and calculation for obtaining time data I and II to be described later by multiplication with the read fundamental wave data. The value is calculated.

Furthermore, as shown in FIGS. 6 to 8, the interval (time; Tai) from the peak of the carrier wave 13a having a negative slope to the intersection αa between the carrier wave 2 and the fundamental wave data is the time data I. The time data II is the interval (time; Tbi) from the valley of the positive carrier wave 13b to the intersection αb between the carrier wave 2 and the fundamental wave data. In addition, the second
The calculated value i is stored in the memory 12d corresponding to the time data I and II (shown in FIG. 6).

Next, the operation of the above inverter control device will be described with reference to FIG.
Description will be given based on the flowchart of FIG. 10 and the time chart.

First, assuming that the operating frequency command of the compressor 1 is, for example, 16 Hz, F16 is set in the symbol (F) (step ST1). At this time, since the predetermined time of the PWM timer in the control unit 10 is set to the half cycle of the carrier wave,
The PWM timer repeatedly operates in that cycle (for example, 150 μs). Then, the timer time of that PWM timer elapses,
That is, it is determined whether it is the timing of the rise or fall of the PWM timer, and if the timer time has not elapsed, it is determined whether the operation frequency has been changed (step ST2). When the operating frequency is not changed, the timer data obtained based on the step data (a fixed number; 20 pieces) stored in the internal memory RAM10a is set in real time, and this real timer sets the real timer I / O port. Is controlled to be reversed. By this inversion control, the PWM waveform for controlling the compressor 1 at the above 16 Hz is obtained from the real timer I / O port.

When the operating frequency is changed, for example, 16
When the frequency is changed from Hz to 17 Hz (step ST2), the timer I (for example, a timer of 0.1 sec) is set (step ST3). Furthermore, the symbol F17 of the new frequency (17Hz)
Is set (step ST4), and the changing flag (HF) indicating the frequency change is set (step ST4).
Five). Then, it is determined whether the change is an increase or decrease in frequency (step ST6). in this case,
Since the frequency has been changed from 16 Hz to 17 Hz, the process proceeds to step ST7, and the start address (SA) for reading the step data of the setting symbol F17 is calculated (step
ST7). Then, since the start address (SA) is set to "5" at the time of the previous symbol F16, 5 + 1 = 6 is set to the start address (SA), that is, the address is shifted by one, for example, step data 20 The range from address "6" to address "25" is specified to obtain the number. Subsequently, the internal memory RAM 10a is rewritten by the step data “3”, “3” “3”, “3”, ... From those addresses “6” to “25” (step ST
8). Then, when the timer I times out (step ST9), it is determined whether or not the start address is the address of the new symbol (F17) (step ST10).
At this time, since the start address is "6", the process returns to step ST6, steps ST7 to ST9 are repeated, and the start address is repeated until it becomes "9". That is, when the operating frequency is changed, the step data “3”, “3” “4”, “4”, ... Of the addresses “9” to “28” of the symbol F17 are finally stored in the internal memory RAM10a. However, the start address does not jump from "5" to "9", but steps one by one, and
The internal memory RAM 10a is shifted by one address, and the step data is rewritten in units of a fixed number. Then, when the start address (SA) reaches the address "9" of the new symbol F17, the above-mentioned changing flag (HF) is set to "0" (the flag is cleared) (step ST11), and the process returns to step ST2. Then, the above steps are repeated.

Here, in step ST8, the internal memory RAM10
While a certain number of step data is stored in a,
The fundamental wave data is sequentially read by the fixed number of step data. That is, as shown in FIG.
If the step data is "3", "3", "3", ..., N
o. is "2", "5", depending on (No.) + (step data)
The fundamental wave data of these addresses are “3”,
"6", "9", ... (For 60 electrical degrees) are read.
Further, the fundamental wave data and the voltage data are sequentially multiplied, but when the maximum control rate of the compressor 1 is 2, 100 times to obtain a control rate with an accuracy of 0.01, that is, the voltage data “200”
Therefore, the fundamental wave data × (voltage data / 200) is sequentially calculated, and the predetermined calculated value shown in FIG. 8 is obtained. Then, the time data corresponding to the calculated value is obtained. For example, when the previous time data is the time data I, the time data II corresponding to the same calculated value is read from the first memory 12d, and the time data I Is 20
It is obtained corresponding to individual step data.

On the other hand, when the operating frequency is changed from 16Hz to 15Hz, the process proceeds from step 6 to ST12 and the start address (SA) is SA.
= SA-1 is sequentially subtracted. That is, the start address (SA) is changed, which is the reverse of the case where the operating frequency is increased, and the internal memory RAM 10a is rewritten from this start address by a fixed number of step data (step ST8). Further, the time data can be obtained from the step data stored in the internal memory RAM 10a as described above.

The above time data I and II are sequentially obtained, and since these time data are set in the real timer as described above,
A PWM waveform that controls the compressor 1 is output from the real timer I / O port. If the above PWM waveform is U phase,
Similarly to the above, the time data I and II corresponding to the V phase and the W phase can be obtained from the fundamental wave data and the voltage data read by the step data stored in the internal memory RAM 10a. Then, since those time data are set in the real timer respectively, the real timer I / O
U-phase, V-phase and W-phase PWM waveforms are output from the port. Real-time I / O by setting time data
When the port inversion control is performed and the timer time of the PWM timer has elapsed, the timer is reset and started, and the next time data is set. Further, similarly to the above, processing for obtaining the next time data I or II is performed by the next step data stored in the internal memory RAM 10a, and the real timer is set to the timer time,
It is executed every half cycle of the carrier frequency. Then, the tenth
As shown in the figure, the real timer I / O port is inverted after time data from the timing of its half cycle,
With this inversion control, a PWM waveform for controlling the compressor 1 at 17 Hz can be obtained.

The real-timer I / O port outputs U-phase, V-phase, and W-phase PWM waveforms as well as their inverted x-phase, y-phase, and z-phase PWM waveforms.
A waveform pulse train is input to the base drive unit 5. Then, the base drive unit 5 causes the power transistor unit 2 to
Each of the transistors is driven, and the pulse-shaped voltage waveform corresponding to the PWM waveform is applied to the compressor 1. Therefore, the U-V, V-W, and W-U phase voltage waveforms are applied to the compressor 1. An approximate sine wave current flows through the compressor 1, and the motor of the compressor 1 is driven.

Thus, the memory unit 12 stores one fundamental wave data of the predetermined sine wave 11, the carrier wave 2 having a constant frequency and the time data I or II based on the fundamental wave data, and the time corresponding to the operating frequency. In order to combine the data I and II, step data (readout interval data) for reading the fundamental wave data is provided, and there are a plurality of step data for each frequency, and the step data is read in correspondence with the operating frequency. The step data to be stored is set to a fixed number (for example, 20), the step data is changed stepwise, and finally the step data of the changed frequency is stored in the internal memory RAM 10a. Therefore, when the operating frequency is variable, the carrier frequency becomes constant, the phase voltage waveform applied to the compressor 1 becomes a pulse of several μs, and the operating frequency resolution is ± 0.2 due to the stepwise change of the step data. Since the frequency rises from Hz to ± 0.25 Hz (in the case of this embodiment) and the frequency changes smoothly, the memory capacity of data does not increase and the current waveform of the compressor 1 becomes closer to a sine wave ( That is, the distortion of the current waveform becomes small), the harmonic components included in the current waveform are reduced, and the noise of the compressor 1 is suppressed.

In the above example, the operating frequency is changed in units of 1 Hz, but due to the improvement in the resolution of the frequency, the operating frequency can be changed in units of ± 0.2 Hz to ± 0.25 Hz. Can be changed more smoothly.

[Effects of the Invention] As described above, according to the inverter control device of the present invention, the predetermined sine wave is equally divided, and the fundamental wave data at the equal division position and the peak or the valley of the carrier wave having a constant frequency are obtained. When reading the time data up to the position corresponding to each height of the carrier wave and the fundamental wave data according to the operating frequency of the load, step data that specifies the reading interval of the address for each operating frequency, and the operating frequency When the operating frequency of the load is changed, a certain number of the above step data are always read and stored in the internal memory (RAM) when the operating frequency of the load is changed, and the basic data is stored based on the stored step data. While reading out the wave data, the fundamental wave data is multiplied by the voltage data to obtain the time data from the calculated value,
Set the same time data in the real timer,
By setting the output waveform of the I / O port to the PWM waveform, the PWM
The memory capacity of the data to obtain the waveform may be small,
Moreover, the carrier frequency can be kept constant with respect to the variable operating frequency, the resolution of the operating frequency can be improved, and the frequency can be changed smoothly.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an inverter control device showing an embodiment of the present invention, and FIGS. 2, 6, and 7 are views for explaining calculation of data used in the inverter control device. FIGS. 3, 4, 5, and 8 are diagrams for explaining the contents of the memory used in the inverter control device, and FIGS. 9 and 10 are diagrams for explaining the inverter control device. Flowchart diagram and time chart diagram, FIG. 11 is a schematic block diagram of a conventional inverter control device, FIG. 12 is a diagram for explaining a method of obtaining data used in the inverter control device of the conventional inverter control device, FIG. 13 is a diagram for explaining the contents of a memory used in the conventional inverter control device. In the figure, 1 is a compressor (load), 2 is a power transistor section (a plurality of switching elements), 5 is a base drive section, 10
Is a control unit (CPU; microcomputer), 10a is an internal memory RAM (temporary storage means), 11 is a sine wave, 12 is a memory unit, 12a is a first memory (for fundamental wave data), and 12b is a second.
Memory (for step data), 12c is a third memory (for voltage data), 12d is a fourth memory (for time data), and 13, 13a and 13b are carrier waveforms.

Claims (1)

[Claims] 1. When controlling a load with an inverter, waveform data corresponding to a target frequency of the load is read from a memory, and a PWM waveform is obtained based on the waveform data.
Switching transistor ON / OFF according to the PWM waveform
In the inverter control device that drives and outputs the voltage waveform applied to the load, the electrical angle of a predetermined sine wave of 60 degrees, 120 degrees, or 180 degrees is equally divided, and the height of the sine wave at the equally divided position is divided. And a plurality of step data for designating a data reading interval when reading the fundamental wave data from the first memory in correspondence with the operating frequency of the load. The second value is stored in the order in which the value increases or decreases according to the increase or decrease of its own address
And a third memory for storing voltage data for multiplying the fundamental wave data to adjust the voltage of the output waveform, and a height of the carrier wave from a peak or a valley of the carrier wave of a constant frequency. A fourth memory that stores a time interval to a position corresponding to the time data as time data; and, when an operating frequency of the load is set, a constant address from a predetermined address of the second memory that corresponds to the operating frequency. Temporary storage means for temporarily storing a predetermined number of each step data in the range, and when the operating frequency is changed, until the changed operating frequency is reached from the current operating frequency, the While shifting the address of the second memory by one address at a time, always read a fixed number of each step data over a fixed address range. The basic wave data is read out and stored in the temporary storage means, and the fundamental wave data is read out based on the respective step data.
Control for repeatedly performing the control of multiplying the voltage data of the memory of the above, the time data corresponding to the calculated value from the fourth memory, and setting the internal real timer every half cycle of the carrier wave. And a real timer I / O according to the set value of the internal real timer.
An inverter controller characterized in that the output of a port is inverted and controlled to obtain the PWM waveform.