KR940007971B1 - Room air conditioner inverter controlling method - Google Patents

Abstract

The method controls a room air conditioner (RAC) by frequency variation, improves a data processing speed, reduces a memory capacity, and varies a phase and frequency of sinusoidal wave. The circuit includes a rectifier (1) which recitifies AC power into DC power, a pulse width modulation signal generator (4) which generates PWM signal, an inverter main circuit (2) which controls a motor drive, and varies a pressure motor speed by frequency variation with power transistor ON,OFF in an inverter main circuit (2). The method memorizes a 1/3 period data of 2-phases: Vdc- root 2 E1COS(wt-π/6),Vdc- root 2 E1SIN(wt), loads output pointer and micro steps from ROM, and controls a room air conditioner.

Description

How to control inverter of room air conditioner

1 is an exemplary waveform diagram of a sine wave and its pulse width modulation (PWM).

2 is an exemplary waveform diagram of sinusoidal wave generation of a conventional one phase (V phase).

3 is an inverter circuit diagram of a room air conditioner to which the inverter control method of the present invention is applied.

4 is an explanatory diagram showing the relationship between line voltages on U, V, and W phases.

5 is a phase voltage waveform diagram of one cycle according to the present invention.

6 is a waveform diagram of a third cycle of FIG.

7 is a flowchart of data processing by a microcomputer in performing an inverter control method of a room air conditioner of the present invention.

8 is an embodiment of the inverter control method of the room air conditioner of the present invention.

* Explanation of symbols for main parts of the drawings

1: rectifier 2: inverter main circuit

3: micom 4: pulse width modulated signal generation controller

5: compressor motor

The present invention relates to an inverter control method, and more particularly, to an inverter control method of a room air conditioner, which is suitable for generating a pulse width modulated signal in varying the capacity of a room air conditioner (RAC) with a variable frequency.

In the conventional inverter control, in order to generate the waveform of the pulse width modulation, the resolution is increased to be close to the sine wave as in the first diagram. In other words, the maximum frequency is 120 Hz, and the maximum resolution is obtained by dividing the sine wave (T ₁ ) by 256 equal parts and dividing the equal period (T ₂ ) by 256 equal parts.

In addition, conventionally, as shown in FIG. 2, the image portion f (t) of the output terminal voltage of the inverter is changed.

Made a sine wave.

However, in the conventional inverter as described above, the pulse width modulated signal is generated close to the sine wave, so that the resolution is too high, and there is a problem in the data processing speed that cannot be handled by an 8-bit microcomputer. Because it is divided into V and W phases and stored in the memory, the size of the memory is limited, and in order to generate a waveform like the second degree, three images f (t) must be applied to each phase. Speed problem.

Accordingly, the present invention does not divide sinusoidal data of one cycle into U, V, and W phases and store it in a memory in consideration of the problems of the conventional circuit as described above. Stored in the memory, by changing the phase and phase only by the processing of the program to reduce the capacity of the memory, and was created to be fully processed by an 8-bit microcomputer, which will be described in detail with reference to the accompanying drawings. Same as

3 is an inverter circuit diagram of a room air conditioner to which the inverter control method of the present invention is applied. As shown in FIG. 3, the rectifier 1 receives a commercial AC power and rectifies the DC power, and the control of the microcomputer 3. Receiving a pulse width modulated signal (PWM) signal and generating a pulse width modulated signal generating controller (4) and the pulse width modulated signal generated by the pulse width modulated signal generating controller (4). The inverter main circuit 2 converts the sinusoidal wave to control the driving of the compressor motor 5, and the power of the inverter main circuit 2 is changed according to the pulse width modulated signal of the pulse width modulated signal generation controller 4 as described above. The speed of the compressor motor 5 is varied by changing the frequency at which the transistor is turned on or off.

On the other hand, the present invention is to generate a pulse width modulation waveform of the controller for the pulse width modulation signal applied to the base of the inverter main circuit (2), the operation thereof will be described as follows.

4 is an explanatory diagram showing the relationship between line voltages on U, V, and W. When the line voltages (e _uv , e _vw , e _wu ) are represented by a complex vector,

It becomes as, and can be expressed by converting it as the following equation.

Where α is ε ^j2π3 .

The above line voltages (e _uv , e _vw , e _wu ) can be divided into three components: image fraction (V ₁₀ ), normal fraction (V ₁₁ ), and inverse phase (V _12). ), It becomes as following formula (1).

For V ₁₀ , V ₁₁ and V ₁₂ ,

On the other hand, if the equation is rewritten as a complex vector, the following equation (2) is obtained.

In the above formula (1) and (2),

That is, V ₁₀ = 0, V ₁₁ = (1-α ² ) V _t1 , V ₁₂ = (1-α) V _t2 ,

∵

Where I _m (V _t0 ) = f (t),

Where θ = π / 3,

It becomes Where f (t) is

The voltage of each phase is made as follows.

In the interval 0≤wt <2π / 3,

e _ut = V _DC

In the interval 2π / 3≤wt <4π / 3,

e _vt = V _DC

In the interval 4π / 3≤wt <2π

e _wt = V _DC

As a result, when the image components f (t) are synthesized with the respective phase voltages U (t), V (t), and W (t) as shown in the waveform diagram of FIG. 5, the phase voltages e _ut , e _vt , e _wt Is the same as b, c, d in FIG.

Also, indicates a waveform of the fifth degree b, c, d as one coordinate and the like to help claim 6, when the exception of the direct current V _DC, as can be seen from the sixth degree waveform, V, W The waveform of the phase is repeated in 1/3 cycle (π / 6 to 5π / 6). Therefore, in FIG. 5, except for the DC V _DC phase, only one third of the data of the two phases (W, V) is stored in the memory, and the phase and phase conversion are processed by the microcomputer 3 to output the output to the port. Just do it.

Meanwhile, a process of processing data in the actual microcomputer 3 will be described with reference to the flowchart of FIG. 7 as follows. In other words, if the power is on, check whether the compressor is on and if it is off, terminate the process. If interrupt occurs while it is on, set the frequency generated at that time, and set the sequence number, interrupt pointer, and pulse width. The output pointer (in the form of a waveform, i.e., the phase changes in one cycle) and the microstep (large and small), ST0 to ST4, are loaded from the ROM together with the large and small data.

After checking the status of the outdoor unit, specifying the output port of the microcomputer, setting the interrupt time, increasing the frequency by 1 and repeating the first step again.

8 is an embodiment executed by the above process.

As described above, the present invention has the effect of improving the data processing speed while reducing the memory capacity by storing only one-third period and two-phase data of the sine wave in the memory and changing the phase and phase only by the program processing. do.

Claims (1)

In order to generate the pulse width modulation waveform, the voltage of each phase is changed to V _DC . , With the exception of the above V _DC , Only two-thirds of the data is stored in memory, and if an interrupt occurs when the compressor is on, the frequency generated at that time is set and the output pointer, together with the sequence number and interrupt pointer, the larger pulse width, and the smaller data. Load the microstep from the ROM, check the status of the outdoor unit, specify the output port of the microcomputer, set the interrupt time, increase the frequency by 1 and repeat the first step again. An inverter control method for a room air conditioner.