JPS6369467A - Air conditioner - Google Patents

Abstract

PURPOSE:To set pause time to satisfy a minimum requirement minimum value, by a method wherein pause time of a transistor contained in an inverter is adjusted according to operation temperature and operation frequency using software. CONSTITUTION:To each frequency data of a motor-driven compressor 4, operation temperature of corresponding transistors Q1-Q6 is estimated, and variation of storage time and drop time by temperature is determined from the operation temperature, and based on the variation pause time of the transistors Q1-Q6 contained in an inverter 3 is previously determined and stored. Control operation of an air conditioner is as follows. First, in response to a room temperature or the like, a routine generating base drive signal corresponding to operation frequency supplied to the motor-driven compressor 4 is selected. Next, base drive signals BU-BZ are supplied from a control device 5 to the transistors Q1-Q6 of the inverter 3, and three-phase AC output corresponding to the base drive signals is supplied from the inverter 3. Thereby pause period corresponding to variation of the operation frequency can be set.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an air conditioner, particularly an inverter-controlled tXl
This invention relates to a 91m circuit for a variable capacity air conditioner based on K2.

[Prior Art] FIG. 4 is a diagram showing the configuration of a 1rilJ control circuit system of a variable capacity air conditioner. In Fig. 4, the control circuit system of a variable capacity air conditioner includes a converter 2 that receives input from an AC power source 1, rectifies and smoothes it, and outputs it, and a three-phase AC voltage that receives DC voltage from the converter 2. 1I which converts the output frequency and output voltage of the inverter 3 to the electric compressor 4 and the inverter 93 to 1ilJlIjl.
It consists of Ii Gosoba 5.

Converter 2 receives the output of AC power supply 1, rectifies it, and converts it to DC! I! It is composed of a smoothing capacitor 22 for removing AC components contained in the rectifier 21, such as It21.

Inverter 3 has six transistors (np in the figure) to convert the series output of converter 2 into three-phase
Including commuting to school. The first phase output is connected in series to a transistor Q1 that performs on/off operations in response to a base drive signal @3u, and a transistor Q1 that performs on/off operations in response to a base drive signal 3x. transistor Q4. The second phase output consists of transistor Q2, which operates on and off in response to the base drive signal [3V, and transistor 0
2 and a transistor Q5 which is connected in series with the base drive signal By and turns on and off in response to the base drive signal By. The third power Aikawa includes a transistor Q3 that operates on and off in response to a base drive signal 3w, and a transistor 03.
A transistor Q6 is connected in series with the base drive signal 3z and turns on and off in response to the base drive signal 3z.

Control unit V! 15 applies an It, II signal base drive signal) to the inverter 3 according to a predetermined routine in response to, for example, the indoor temperature in which the air peace machine is installed, and thereby changes the output frequency and output of the inverter 3. Adjusting the voltage.

In the inverter 3, the DC output from the converter 2 is converted into a three-phase AC output by turning on only one of the same-phase transistors (for example, transistors Q1 and Q4).

FIG. 5 is a diagram showing the relationship between base current and collector current of a transistor, and is a diagram showing general switching characteristics of a transistor. Normally, in a bipolar transistor as shown in FIG. 5, there is a time delay between the base current 1B and the collector current I, as shown in FIG. In other words, base 7M style 16
Even if the collector current falls, the collector current does not fall rapidly, and the accumulation time Ts due to the N stacking tube in the transistor
A delay in the switching operation occurs due to the falling time Tg and the falling time Tf. Therefore, keeping the transistor in the off state
Even if the base current 1a is lowered in order to reduce the collector current 1c, the collector current 1c continues to flow for a while, so the transistor remains on during this time. Therefore, in the inverter 3 shown in FIG. 4, the in-phase upper and lower transistors QII3 and Q4, Q2 and Q5, Q3 . In order to prevent the transistors from being destroyed due to simultaneous conduction of tj and Q6, a delay time called a rest time is provided in which the 1-transistors of the same phase are simultaneously turned off in each phase.

FIG. 6 is a timing diagram that does not show the operation of transistors in the same phase. ′! In other words, as seen from the operating waveform diagram in Figure 6, after the base drive signal 3x fell, the base drive signal 3u rose after the pause time had elapsed, and in the same way, the base drive signal @3u fell. Base drive signal 3x after the pause time has elapsed
is made to stand up. Of course, a base drive signal is applied to the upper and lower transistors in the same phase so that one transistor is reliably turned off and the other transistor is turned on. There are generally two methods for setting this pause time: one is setting it using hardware as shown in FIG. 7, and the other is setting it using software as shown in FIG.

FIG. 7 is a diagram showing a configuration in which the generation timing of the base drive signal is set by hardware.

In FIG. 7, 1i' consisting of a microcomputer
j Fit part 50 is electric compression! A false signal υj is generated depending on the operating frequency of a4, etc. This control signal is resistor IR
(And the rise of the capacitor C is slowed down by a delay circuit, and the signal is sent to the buffer circuit 51. The buffer 7 circuit 51 shapes the waveform of the given signal and converts it into a square wave 1) to output a base drive signal. . In this configuration J3, the pause time provided for the transistors in the same phase is set by the delay time provided by the resistor R6 and the capacitor C.

FIG. 8 is a diagram illustrating the operation steps when controlling the pause time for transistor operation by software. In FIG. 8, first, a routine corresponding to the operating frequency of the electric compressor 4 is selected (Sl), and a be-strive signal corresponding to the selected output signal is output as ill l1.
Output from the tl device 5 (S2), next time
The output cover turn of the stripe signal and the cover turn for the base drive signal at that time are ANDed (or OR), and the logical result is output (33).The operation changes depending on the next output cover turn. This is done to temporarily put the transistors in an intermediate state (both transistors in the same phase that change state are in the off state).Next, the signal output is stopped for a predetermined waiting time. <84), and after this predetermined time has elapsed, the next output cover turn to receive the base drive is output (85). After outputting the next output cover turn, a return operation is performed to return to step S1 ( 86).

In order to prevent the transistors of the same phase from turning on at the same time and destroying the transistors when outputting three-phase AC as described above, a predetermined pause time is provided by software control. There is.

Here, the pause time in software vJIII corresponds to the time consisting of step S3 and step S4 in FIG.

[Problem to be Solved by the Invention] During the rest time, both transistors in the same phase are in the off state, so 'f! Does the current flowing through the single-motion compressor 4 include a pulsating component? Torque fluctuation occurs in the dynamic compression fi4. Therefore, reducing the downtime as much as possible will result in good results for the electrical characteristics of the electric compressor. However, in the conventional inverter 8MJ control circuit, the switching characteristics of the transistors change depending on the operating conditions, etc., and although there are cases where it is possible to reduce the downtime, the downtime is uniquely 311 1. Because the time period was determined, not much consideration was given to the electric compressor. :
.

Therefore, an object of the present invention is to provide an air conditioner that can eliminate the above-mentioned problems, suppress the period of downtime to the necessary minimum, and thereby minimize the adverse effects of the downtime on electric compression b1. It is to provide.

Means for Solving Problem E 1 The air conditioner a of the present invention is configured to adjust the downtime depending on the operating frequency of the electric compressor or the operating temperature of the i-ran transistor included in the inverter.

1 Effect] Normally, the delay time (the sum of the accumulation time and the falling time) of a transistor changes depending on the temperature; as the temperature rises, the delay time becomes longer, and as the temperature falls, the delay time becomes shorter.

Further, the operating humidity of the transistor is related to the switching loss of 1-range, and when the switching loss is large, the element 1&1 degree increases. This switching loss includes a loss caused by excessive If ff='i during switching and a loss caused by the saturation voltage VcH (sat) in the on state. The former is proportional to the number of times the transistor switches, and the latter is proportional to the number of times the transistor switches, and the latter is proportional to the number of times the transistor switches. proportional to the flow.

On the other hand, the number of switching times is uniquely determined according to the operating frequency of the electric compressor, and collector 1! The current increases as the frequency increases, so there is a proportional relationship between the operating frequency of the electric compressor and the switching loss of the transistor, and a proportional relationship between the switching loss of the transistor and the element temperature (the operating temperature of the transistor). It is in. As a result, a proportional relationship exists between the switching loss of the transistor and the element temperature, and it becomes possible to estimate the increase in element temperature from each operating frequency.

Therefore, by adjusting the downtime provided in the iqa of the inverter according to the operating frequency or element temperature, the downtime can be reduced to just one! ! ! It is possible to set the minimum distance to 1m.

[Embodiments of the Invention] First, before describing embodiments of the present invention, the theoretical background supporting this invention will be explained.

Normally, the storage time 7sig and fall time T'' in the switching characteristics of bipolar transistors change depending on humidity, and as the temperature rises, the storage time 7sig decreases.

On the other hand, the fall time T becomes longer as the temperature decreases, while it becomes shorter as the temperature decreases.Therefore, it is necessary to change the length of the rest time depending on the humidity of the element.On the other hand, the operating temperature of the transistor is related to its switching loss. and
If the switching loss is large, the operating temperature of the transistor increases. In general, the switching losses of transistors can be broadly divided into three types: ■Loss that occurs during the transition of switch-on operation, ■Loss due to the saturation voltage Vc E (sat) in the on state, and ■Loss that occurs during the transition of switch-off operation. be. Of these, the losses that occur during the transient switching operation of ■ and ■ are proportional to the number of times the transistor is switched, while the loss of one due to the saturation voltage of ■ is the collector 1! current) is proportional to C.

FIG. 2A is a diagram showing the relationship between the operating frequency of the electric pressure N machine and the number of switching times of the transistor included in the inverter. As shown in FIG. 2A, the number of times the transistor is switched is uniquely determined by the operating frequency of the electric compressor, and on the other hand, the collector current 10 flowing through the transistor increases as the frequency increases. , the relationship between the operating frequency of the electric compressor and the switching loss of the transistor is determined. Here, the second
In Figure A, the number of switching times decreases as the operating frequency increases, but as the operating frequency increases, the pulse interval of the base drive signal given to the transistor becomes shorter, and once for multiple base drive signals. This corresponds to the fact that the transistor performs a switching operation.

FIG. 2B is a diagram showing the relationship between the switching loss of the transistor and the operating frequency of the electric compressor.

The relationship between the operating frequency and the switching loss in the transistor can be determined through the relationship between the number of switching times and the operating frequency determined from FIG. 2A, and the relationship is shown in FIG. 2B. On the other hand, since there is a proportional relationship between the switching loss of a transistor and the operating temperature of the transistor, it is safe to consider that the switching loss (vertical axis) in FIG. 2B is the operating temperature of the transistor. Therefore, it is possible to estimate the temperature rise of the transistor from each operating frequency data (for the electric compressor). The present invention is carried out based on the above-mentioned theory, and one embodiment of the present invention will be described below.

First, from the relationship shown in FIG. 2B, the operating degree of the transistor corresponding to each frequency data of the electric compressor is estimated. From this estimated temperature of the transistor, the temperature-related changes in the accumulation time Tstg and fall time Tl are determined, and based on this, the period of rest time of the transistor included in the inverter 3 is determined in advance, and this is stored. put.

Figure 1 shows i/1 of an air conditioner which is an embodiment of this invention.
FIG. 1 is a diagram showing the operation of one circuit. Hereinafter, the control operation of the air peace machine which is an embodiment of the present invention will be explained with reference to the tR1 diagram.

First, electric compression responds to the indoor temperature where the air conditioner is installed! A routine is selected ($10) to generate a base drive signal corresponding to the operating frequency applied to 114. At this time, is it already in the base drive output routine? ! ! A time period corresponding to the operating frequency of the dynamic compression rock 4 is set. Next, according to the selected base drive output routine, the base drive signal is sent from the control device 5 to the transistors 01 to Q6 of the inverter 3.
given to each base. Transistor 01~
Q6 turns on or off in response to the applied base drive signal, and outputs a signal from inverter 3 to 3 in response to the applied base drive signal.
A phase alternating current output is given to the electric compressor 4. After a predetermined period of time has passed after the base drive signal is output (this pulse period is also set in the output routine), the pattern of the base drive signal that should be output next time and the base drive signal that is currently being output AND with pattern
(or OR) is taken and the logical result is output.
Q6 transitions from the current state to an intermediate state before transitioning to the next state. This prevents the transistors in the same phase from being turned on at the same time and prevents the transistors from being destroyed (812). After the AND (or OR) output is output, the output including the base drive @ The time that has already been set in the routine is output, and the generation of the base drive signal is stopped ($13
). After this holding time has elapsed, the next base drive signal cover turn is applied to the inverter 3 (814)
, After that, the process returns to step 10 via step 15 and the above-described operation is repeated. Here, in step 812, the AND (or OR) with the next base drive output cover turn changes depending on the polarity of the transistor included in the inverter 3; Only logical results are output. As described above, in the method of setting the down time of the transistors included in the inverter 3 using software, the time included in the down time is determined corresponding to each operating frequency of each electric compressor, and each of the electric compressors is By setting 43 in correspondence to each of the base drive output routines selected for each operating frequency, it is possible to set the down time in accordance with the change in the operating frequency of the electric compressor.

In the above embodiment, the down time setting is determined and stored in advance in accordance with the operating frequency data of the electric compressor, and the down time is determined using the stored time using software. The decision is made based on the However, the duration included in this rest time is closely related to the operating temperature of the transistors included in the inverter, and the temperature of the transistors is directly measured.
The holding time may be changed depending on the measured temperature.

That is, as described above, the delay in the switching operation of the transistor, that is, the delay time T stg and the fall time 1'l, change with temperature, and this relationship can be easily determined. Therefore, by setting the hold time according to changes in the open and fall times during accumulation of this transistor, it is possible to set the hold time corresponding to the element temperature. That is, in this embodiment, the advantage of the method of setting the pause time using software, that is, the length of the pause time can be set by a program, is utilized to adjust the pause time according to the operating temperature of the transistor. This is an attempt to set a target.

FIG. 3 is a flow diagram showing the operation of a control circuit according to another embodiment of the present invention. Hereinafter, referring to FIG. 3, a description will be given of the operation of 1 and 1J, which is another embodiment of the present invention.

First, the element temperature (operating temperature of the transistor) and the corresponding duration included in the rest time are determined in advance and
l Store it in the III device 5. Here, it is necessary to accurately measure the operating temperature of the transistors, but since the six transistors that make up the inverter 3 are usually modularized into one package, it is necessary to incorporate the Si temperature sensor into this package. Alternatively, it is possible to accurately detect the element temperature by mounting a temperature sensor near the package. Depending on the conditions such as the indoor temperature where the air peace machine is installed, the Iζ base drive output cultin is selected according to the required operating frequency of the electric compressor 14 (8201°). A temperature detector measures the element temperature and determines whether the transistor temperature has risen since the last time the base drive signal was output. <3213° If the transistor temperature rises at this time, a corresponding The waiting time is selected and the waiting time is lengthened (822).If the temperature of the transistor has not increased, it is determined whether the temperature of the transistor has decreased since the last time the base drive signal was output. (823).If the element temperature has decreased compared to the previous time, the retention time corresponding to the decreased temperature is selected, and the retention time is shortened ($24).
Here, if the temperature of the transistor is the same as when the base drive signal was output last time, the holding time is not changed at all and the same holding time as the previous time is selected. When the duration setting is completed, a base drive signal is output to the inverter 3 according to the selected base drive output routine.<8
25), the base drive signal is output for a predetermined time (
When the pulse I1 period of the base drive signal has elapsed,
Next, the base drive signal pattern to be output next time and the current base drive signal pattern are ANDed (or OR), and the logical result is output for a predetermined time period (826). This logical result is output. When this period ends, the selected duration time is output and the output of the drive signal is stopped (827).When this duration period has elapsed, the next base drive signal output pattern is output from the inverter 3.
(828).

After the output of the next base drive signal is completed, the process moves to step $29, where a return operation is performed, and then the process moves to step 20, where a similar operation is performed. As mentioned above, by detecting the operating temperature of the transistor and adjusting the hold time accordingly, the necessary minimum pause vf can be achieved in response to changes in the delay time (sum of accumulation time and fall time) of the transistor. It is possible to set the interval.

[Effects of the Invention] As described above, according to the present invention, the down time of the transistor included in the inverter can be adjusted using software in response to the operating temperature of the transistor and the operating frequency given to the electric compressor. Because it's ill,
It is now possible to set the minimum required rest time according to the delay time (sum of M product time and fall time) of the transistors included in the inverter, thereby minimizing the period during which transistors in the same phase are simultaneously in the off state. This makes it possible to reduce the adverse effects on the electric compressor such as torque fluctuations in the dynamic compressor and pulsating current in the line current.

[Brief explanation of the drawing]

Figure 1 shows an illustration of an air conditioner that is an embodiment of the present invention.
I! It is a flowchart which shows I operation|movement. Figure 2 is a diagram showing the relationship between the operating frequency of the electric compressor, the operating temperature of the transistor, and the number of switching times, and Figure 2A is a diagram showing the relationship between the frequency of the electric compressor and the number of switching times of the transistor included in the inverter. , FIG. 2B is a diagram showing the relationship between the operating frequency of the N-dynamic compressor and the element temperature via switching loss in the transistor. FIG. 3 is a flowchart showing control operations in an air conditioner according to another embodiment of the present invention. FIG. 4 is a diagram showing a schematic configuration of a control circuit of a conventional air peace machine to which the present invention is applied. FIG. 5 is a diagram showing the relationship between base current and collector current of a transistor used in an inverter.
FIG. 3 is a diagram showing on/off operation characteristics of a transistor. FIG. 6 is a timing chart showing the operation of transistors included in the inverter. FIG. 7 is a diagram illustrating a configuration in which the pause time given to the transistors included in the inverter is set using hardware. FIG. 8 is a flow diagram showing the operation of the v control circuit when using software to set the down time for the transistors included in the inverter. In the figure, 1 is an AC power supply, 2 is a converter, 3 is an inverter, 4 is an electric compressor, 5 is a control device, and Q1 to Q6 are transistors. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Collar 5 Diagram 6 Funeral Diagram

Claims (4)

[Claims] (1) A converter that receives AC output from an AC power source, converts it to DC power, and outputs it; an inverter that receives DC power from the converter, converts it to three-phase AC voltage, and outputs it to the electric compressor; An air conditioner comprising: a control device that controls the output frequency and output voltage of the inverter by controlling the operation of series-connected transistors provided for each phase of the three-phase output of the inverter; In each output phase, a pause time is provided for the operation of the transistors so that the transistors provided in the same phase do not become conductive at the same time, and the pause time is set according to the operating frequency of the electric compressor. An air conditioner characterized in that the air conditioner is configured to change the temperature. (2) The rest time adjustment means includes means for pre-storing a rest time according to the operating frequency of the electric compressor, and a means for storing a corresponding rest time from the storage means according to the operating frequency of the electric compressor at that time. and means for reading out the time.
An air conditioner according to claim 1. (3) a converter that receives AC output from an AC power source, converts it to DC power, and outputs it; an inverter that receives DC output from the converter, converts it to three-phase AC, and outputs it to the electric compressor; and the inverter. and a control device that controls the output frequency and output voltage of the inverter by controlling the operation of series-connected transistors provided for each phase of the three-phase output, the air conditioner comprising: In each phase, a pause time is provided for the operation of the transistors so that the transistors provided in the same phase do not become conductive at the same time, and the pause time is determined according to the operating temperature of the transistors included in the inverter. An air conditioner characterized in that the air conditioner is configured to change the temperature. (4) The rest time adjusting means includes: a means for storing a rest time determined in advance according to an operating temperature of a transistor included in the inverter; and a means for measuring an operating temperature of a transistor included in the inverter; means for reading out a corresponding rest time from the storage means in response to the measured temperature from the operating temperature measuring means;
An air conditioner according to claim 3.