JP5151729B2 - Power supply device and device provided with the same - Google Patents

Description

  The present invention relates to an AC power supply device provided in a device such as an air conditioner, and more specifically, an instantaneous voltage fluctuation in which an input power supply voltage is temporarily reduced occurs, and is generated by a subsequent power supply voltage recovery. The present invention relates to a configuration for preventing component destruction due to inrush current.

  Conventionally, what is shown in the circuit diagram of FIG. 7 is disclosed as a power supply device that suppresses a re-entry current at the time of power recovery when an instantaneous interruption of an AC power supply occurs. Such a power supply device is used in various devices, but is often used particularly in an air conditioner in which a large load current flows.

  This power supply apparatus is configured as shown in FIG. A bridge diode 82 that rectifies by inputting an AC power supply 81, a first capacitor 83 connected between the positive terminal and the negative terminal of the bridge diode 82, and an inductor connected in parallel to the first capacitor 83 The first resistor 84 having one end connected to the negative terminal of the bridge diode 82 and the other end connected to the negative terminal of the first capacitor 83 and a thyristor 85 as a switch element. And a parallel circuit.

  Note that the anode terminal of the diode 88 is connected to the connection point between the inductor 86 and the transistor 87, and one end of the smoothing capacitor 89 is connected to the cathode terminal of the diode 88, and the other end of the smoothing capacitor 89 is connected to the first capacitor 83. Connected to the negative terminal. Therefore, both ends of the smoothing capacitor 89 are terminals for the DC output voltage. The base terminal of the transistor 87 is switching-controlled by the control unit 90, and is controlled so that the DC output voltage becomes a DC output voltage setting value that is a control target voltage by the boosting operation by the switching control. In the normal case, the DC output voltage setting value is set to an optimum standard voltage for the load of the power supply device.

  In addition, from the AC power supply 81, first and second diodes 91 and 92 connected in parallel to the bridge diode 82, and a second capacitor 93 connected in parallel to the first and second diodes 91 and 92 are provided. A series circuit of second and third resistors 94 and 95 connected in parallel to the second capacitor 93, a third capacitor 96 connected in parallel to the third resistor 95, and one end of A trigger circuit 98 including a Zener diode 97 connected to the connection point of the second and third resistors 94 and 95 and having the other end connected to the gate terminal of the thyristor 85 is provided.

  The trigger circuit 98 rectifies the input voltage of the AC power supply 81 by the first and second diodes 91 and 92, smoothes the output by the second capacitor 93, and outputs the output to the second and third resistors 94 and 92. The voltage is divided by 95, the divided voltage is detected by the Zener diode 97, the detection signal is applied to the gate of the thyristor 85, and the thyristor 85 is turned on / off by the input voltage of the AC power supply 81.

  In the above configuration, when the AC power supply 81 is turned on, the thyristor 85 is non-conductive, so that the inrush current to the first capacitor 83 is suppressed by the first resistor 84. Thereafter, a charging current flows to the third capacitor 96 through the second resistor 94 connected to the cathodes of the first and second diodes 91 and 92 and the positive electrode of the second capacitor 93, and the potential of the zener diode 97 Is reached, the voltage is applied to the gate of the thyristor 85 through the Zener diode 97.

  Here, the thyristor 85 can be turned on by setting the Zener voltage to a voltage necessary for the thyristor 85 to turn on. Therefore, thereafter, a charging current flows to the first capacitor 83 through the thyristor 85.

  Here, when the input of the AC power supply 81 is interrupted by an instantaneous power failure, the discharge current of the third capacitor 96 flows through the third resistor 95, so that the potential of the positive electrode of the third capacitor 96 decreases and the Zener diode 97 turns off. Therefore, the gate voltage of the thyristor 85 is also lower than the potential Vgt at which the thyristor 85 is turned on, and the thyristor 85 becomes nonconductive. After that, when returning from the instantaneous power failure state, the thyristor 85 is already in a non-conducting state, so the re-entry current is suppressed by the first resistor 84 (see, for example, Patent Document 1).

  The above is the operation in the instantaneous power failure state of the AC power supply, but there is what is called instantaneous voltage fluctuation in addition to the instantaneous power failure. This means a state where the AC power supply voltage fluctuates temporarily, for example, for about 20 to 500 milliseconds. When the voltage rises temporarily, it is stabilized by the constant voltage circuit and there is almost no problem. However, when the voltage drops temporarily, a problem occurs. This is a problem of inrush current that flows to the smoothing capacitor when the electric charge of the smoothing capacitor is reduced due to a temporary voltage drop and the instantaneous voltage fluctuation is finished and the voltage returns to a normal voltage.

  FIG. 8 is a timing chart in the power supply device 81. 8A shows the AC power supply voltage, FIG. 8B shows the DC output voltage, FIG. 8C shows the DC output voltage setting value, and FIG. 8D shows the AC input current. Note that the DC output voltage set value in FIG. 8 (3) is a set value set in the control unit 90 described as a pseudo waveform, and is actually set by a microcomputer (not shown) in the control unit 90. The value is shown.

  As shown in the timing chart of FIG. 8, when the voltage of the AC power supply 81 decreases, the control unit 90 feeds back the voltage drop to increase the ON time of switching of the transistor 87. However, since the on-time of the transistor 87 is controlled to be longer than that in the case of the rated AC power supply voltage when the instantaneous voltage fluctuation ends and returns to the normal voltage, the energy accumulated in the inductor 86 is smoothed by the smoothing capacitor 89. Flows in as an inrush current. If the value of the inrush current exceeds the allowable value of the diode 88 and the smoothing capacitor 89, these components may be destroyed.

  Generally, a temporarily allowable current is defined as a surge current in an electrolytic capacitor or a diode. Therefore, as described above, the power supply device is provided with a circuit for suppressing a surge current when the power is turned on. Further, in order to withstand the instantaneous voltage fluctuation as described with reference to FIG. 8, a component having a sufficient margin against the surge current is selected and used.

However, in devices such as an air conditioner equipped with a compressor, instantaneous voltage fluctuations may occur in devices that require a long time from when the power is turned off to when the power is turned on again and the compressor rotates normally and air conditioning is resumed. In order to maintain the comfort of air conditioning by continuing the compressor operation as much as possible even if it occurs, you must use parts with sufficient margin against surge current. Is expensive and its use has not been practical as a product.
JP-A-5-316723 (page 3, FIG. 1)

  The present invention solves the above-described problems, and in an apparatus equipped with a power supply device through which a large current flows, such as an air conditioner, an inrush that occurs at the time of recovery from an instantaneous voltage fluctuation in which the AC power supply voltage temporarily decreases The purpose is to reduce the cost by reducing the current and using components with a small allowable surge current.

In order to solve the above-described problems, the present invention provides an input voltage detection means for detecting an input AC voltage, a booster circuit that boosts a DC voltage obtained by rectifying the AC voltage and supplies the boosted voltage as an output voltage to the load, and the output An output voltage detecting means for detecting a voltage, a detection result of the input voltage detecting means and the output voltage detecting means is inputted, and an output voltage value of the booster circuit is set as a target voltage value for control And control means for controlling so that
The control means reduces the set voltage value stepwise as time passes when the AC voltage becomes a predetermined voltage or less, and sets the set voltage when the AC voltage becomes the predetermined voltage or more. The value is returned to a value before the AC voltage becomes equal to or lower than the predetermined voltage.

By using the above means, according to the power supply device of the present invention,
The invention according to claim 1 can suppress the inrush current to the booster circuit when it recovers from the decrease of the input AC voltage due to the instantaneous voltage fluctuation, and can prevent the destruction of the components in the booster circuit. In addition, since a component having a low surge current can be used as a component in the booster circuit, the cost can be reduced.
In addition, the longer the instantaneous voltage fluctuation period, the lower the voltage of the capacitor, and the inrush current increases corresponding to this voltage, so even if the period during which the input AC voltage drops due to instantaneous voltage fluctuation is unknown is output little by little By reducing the voltage, it is possible to suppress a decrease in output voltage while suppressing an inrush current that is generated.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail as examples based on the attached drawings.

  FIG. 1 is a block diagram of a main part of an outdoor unit 20 of an air conditioner incorporating a power supply device 1 according to the present invention. The outdoor unit 20 includes a power supply device 1 and a load 3 connected thereto. The power supply device 1 inputs an AC power supply 2 and rectifies it, and then supplies a predetermined DC voltage to the load 3. The load 3 includes an inverter 31 that inputs a DC output voltage of the power supply device 1 and a compressor motor 32 (not shown) that is driven by the inverter 31.

  The power supply device 1 includes a bridge diode 6 that rectifies the input AC power supply 2, an input voltage detector 4 that detects the voltage of the input AC power supply 2, and an input current detector 5 that detects the current of the input AC power supply 2. The inductor 7 has one end connected to the positive side of the bridge diode 6, the other end connected to the anode terminal of the diode 8, the collector terminal at the anode terminal of the diode 8, and the negative side of the bridge diode 6 at the emitter terminal. A transistor 9 (switching element) connected to the capacitor 8, a capacitor 11 having one end connected to the cathode terminal of the diode 8 and the other end connected to the negative electrode side of the bridge diode 6, and a DC that detects the voltage across the capacitor 11. While outputting a switching signal to the voltage detector 10, the base terminal of the transistor 9, and the inverter 31, And a control unit 12 that the detection signal of the force-voltage detector 4 and the input current detector 5 and the DC voltage detector 10 is input. The voltage across the capacitor 11 becomes a DC voltage output supplied to the load 3.

  The load 3 of the power supply device 1 is a compressor motor 32 mounted on an outdoor unit 20 of an air conditioner (not shown) and an inverter 31 that drives the compressor motor 32, and a DC output voltage output from the power supply device 1 is obtained. This is supplied to the motor 32 via the inverter 31. In order to apply a predetermined voltage, for example, 200 V (volts) to the load 3, the voltage rectified by the bridge diode 6 is boosted as a chopper type switching circuit including an inductor 7, a transistor 9, a diode 8, and a capacitor 11. The circuit 13 is configured to boost the voltage.

  Therefore, the control means 12 monitors the DC output voltage via the DC voltage detector 10, and outputs a signal subjected to switching control to the base terminal of the transistor 9 so that this voltage becomes a predetermined voltage. The predetermined voltage value that is the target of control is stored in the control means 12 as a DC output voltage setting value. Therefore, the DC output voltage can be set to an arbitrary value by rewriting the DC output voltage setting value. In this embodiment, description will be made on the assumption that this voltage control is always performed unless otherwise specified.

  In this embodiment, the control means 12 controls the power supply device 1 and also controls the inverter 31 at the same time. However, the control means 12 may be configured using separate control means. In this embodiment, an outdoor unit of an air conditioner has been described. However, the present invention is not limited to this and can be widely applied to devices having a load through which a large current flows.

  The input voltage detector 4 detects the voltage of the AC power source, and the detection result is constantly monitored by the control means 12. By this monitoring, the control means 12 can know the power-off, the occurrence and recovery of instantaneous voltage fluctuation or instantaneous interruption, the timing of the zero cross point of the voltage, and the like. The input current detector 5 detects the current of the AC power supply, and the detection result is constantly monitored by the control means 12. With this monitoring, the control means 12 can know the peak value of the current and the current consumption. Note that the input voltage detector 4 and the input current detector 5 are provided as standard in an air conditioner, for example.

  FIG. 2 is a timing chart in the power supply device 1. 2 (1) shows the AC power supply voltage, FIG. 2 (2) shows the DC output voltage, FIG. 2 (3) shows the DC output voltage set value, and FIG. 2 (4) shows the AC input current. Note that the DC output voltage setting value in FIG. 2C is a pseudo waveform of the setting value set in the control means 12.

  A microcomputer (not shown) in the control unit 12 controls the DC output voltage output from the booster circuit 13 to be a DC output set voltage value that is a voltage value targeted for control. Therefore, the DC output set voltage can be changed to an arbitrary voltage by rewriting the DC output set voltage value.

  A feature of the present invention is that the DC output voltage set value is temporarily reduced when an instantaneous voltage fluctuation occurs. Thereafter, when the voltage returns to the normal voltage, the DC output voltage set value is changed to the set value before the instantaneous voltage fluctuation occurs. For this reason, the DC output voltage when returning from the instantaneous voltage fluctuation is low, and the inrush current to the capacitor 11 is reduced as compared with the case where the DC output voltage set value is made constant.

  Next, the processing of the control means 12 according to the present invention will be described with reference to FIGS.

  First, for example, when the voltage of the AC power supply 2 is the rated voltage in the outdoor unit 20, the control unit 12 sets the DC output voltage setting value to 200V so that the DC output voltage becomes a predetermined voltage (standard voltage), for example, 200V. Set to the corresponding value. Then, the transistor 9 is switched so that the DC output voltage becomes this set voltage.

  Here, when the control means 12 detects that an instantaneous voltage fluctuation has occurred, the control means 12 temporarily changes the DC output voltage setting value from 200V to 180V and sets it. Note that the control means 12 constantly monitors the voltage state of the AC power supply via the input voltage detector 4, and recognizes that an instantaneous voltage fluctuation has occurred when this voltage falls below the rated operating voltage range. Conversely, when this voltage returns to within the rated operating voltage range, it is recognized that the instantaneous voltage fluctuation has ended. Further, when this voltage becomes equal to or lower than the lowest operable voltage of the power supply device 1, the supply of the DC output voltage is stopped.

  As a method of determining the voltage state of the AC power source described above, for example, there is a method of monitoring a half cycle period of the AC power source voltage and determining the peak voltage value during this period. This method is also used in this embodiment. Therefore, the detection of the instantaneous voltage fluctuation may be delayed for the maximum half period of the AC power supply voltage after the instantaneous voltage fluctuation occurs. In this embodiment, the timing at which the actual occurrence of instantaneous voltage fluctuation and the end of instantaneous voltage fluctuation are detected are referred to as instantaneous voltage fluctuation occurrence (recognition) and instantaneous voltage fluctuation end (recognition), respectively.

Then, the control means 12 temporarily sets the DC output voltage setting value from 200 V to 180 V, then monitors the instantaneous voltage fluctuation, and recognizes the end of the instantaneous voltage fluctuation, and changes the DC output voltage setting value from 180 V to 200 V. Return. As described above, it is necessary to monitor and determine the AC power supply voltage to determine the end of the instantaneous voltage fluctuation, and when this determination is completed, the inrush current has almost converged, and the DC output voltage setting value is restored to the original value. There is no problem even if it returns to the voltage value. If the inrush current has not converged at the time when this determination is completed, the time until the DC output voltage setting value is returned to the original voltage value may be delayed.
FIG. 3 is an example in which the concept described above is further developed. Note that the hardware configuration of the power supply device 1 is the same as that in FIG. 1, and only the processing contents of the control means 12 are different. In addition, about the processing content of the control means 12, the flowchart at the time of using a microcomputer is demonstrated in detail later.

  FIG. 3 is a timing chart in the power supply device 1. 3 (1) shows the AC power supply voltage, FIG. 3 (2) shows the DC output voltage, FIG. 3 (3) shows the DC output voltage setting value, and FIG. 3 (4) shows the AC input current. Note that the DC output voltage setting value in FIG. 3 (3) is a pseudo waveform of the setting value set in the control means 12, and is actually set by a microcomputer (not shown) in the control means 12. The value is shown.

  When recognizing the occurrence of instantaneous voltage fluctuation, the control means 12 changes the DC output voltage setting value to one level, for example, changes from the current DC voltage setting value 200V to 198V, which is 2V lower, and sets it. Then, it waits for a certain period of time, for example, a period of one cycle of the AC power supply voltage. If the instantaneous voltage fluctuation is still occurring, the DC output voltage set value is further lowered by one step and set to 196V.

  In this way, the DC output voltage set value is sequentially decreased. Naturally, since there is a limit to the voltage to be lowered, supply of the DC output voltage is stopped when the voltage drops below the lowest operable voltage of the power supply device 1. Since the control means 12 is shared with a control unit (not shown) of the outdoor unit 20, if the voltage of the AC power source 2 or the DC output voltage is lower than the minimum operable voltage of the outdoor unit, the control unit 12 A power-off process is performed, and thereafter the supply of the DC output voltage is stopped.

  As described above, the reason why the DC output voltage set value is sequentially reduced is that it is not desired to reduce the DC output voltage supplied to the load 3 as much as possible. On the other hand, if the AC power supply voltage decreases due to instantaneous voltage fluctuation, the charge accumulated in the capacitor 11 also decreases, that is, the voltage of the capacitor 11 also decreases. Since it is proportional to the length of the instantaneous voltage fluctuation period, the voltage of the capacitor 11 decreases as the instantaneous voltage fluctuation period becomes longer.

  Therefore, when the instantaneous voltage fluctuation ends, the inrush current to the capacitor 11 increases as the period of the instantaneous voltage fluctuation increases. For this reason, in order to reduce the inrush current that increases corresponding to the period of the instantaneous voltage fluctuation, the DC output voltage set value is decreased corresponding to the period of the instantaneous voltage fluctuation.

  For example, since the inrush current is small when the instantaneous voltage fluctuation period is short, the DC output voltage set value can be kept as low as possible and supplied to the load 3 without much decrease. On the contrary, since the inrush current is large when the period of the instantaneous voltage fluctuation is long, the DC output voltage set value is reduced as much as necessary, and the inrush current is reduced as much as possible.

  On the other hand, when recognizing the end of the instantaneous voltage fluctuation, the control means 12 increases the DC output voltage set value step by step. This is because when a DC output voltage set value that has been gradually reduced, for example, 186V, is changed to the original set value, for example, 200V, an inrush current is generated corresponding to this voltage difference. The set value is raised. As a result, the energy that should become the inrush current is dispersed over time, and as a result, the peak value of the inrush current can be suppressed.

  In the method of FIG. 3, the DC output voltage set value is gradually lowered and gradually raised, but for simplicity, either the DC output voltage set value is gradually lowered or gradually raised. May only be realized. This is effective when the control is realized relatively easily.

  For example, in the method of gradually decreasing the DC output voltage set value, when the occurrence of instantaneous voltage fluctuation is recognized, the DC output voltage set value is changed to one level, for example, changed from the current DC voltage set value 200V to 198V, which is 2V lower, and set . Then, it waits for a certain period of time, for example, a period of one cycle of the AC power supply voltage. If the instantaneous voltage fluctuation is still occurring, the DC output voltage set value is further lowered by one step and set to 196V. In this way, the DC output voltage set value is sequentially decreased.

  Then, when recognizing the end of the instantaneous voltage fluctuation, the control means 12 changes 186V, for example, to the original set value, for example, 200V at once. When the load 3 is relatively light, the inrush current generated by the load 3 is also small, so this is an effective method simply.

  On the other hand, in the case of a method of gradually increasing the DC output voltage setting value, for example, when recognizing the occurrence of instantaneous voltage fluctuation, the control means 12 changes the DC output voltage setting value from 200V to 186V temporarily and sets it. Then, the time from the occurrence of the instantaneous voltage fluctuation to the end is counted. Next, when recognizing the end of the instantaneous voltage fluctuation, the control means 12 increases the DC output voltage set value stepwise in accordance with the length of the instantaneous voltage fluctuation period. This method is used when the load 3 is not significantly affected by fluctuations in the DC output voltage, and is a simple method mainly using suppression of inrush current.

  Next, the processing in FIG. 3 of the control means 12 will be described using the flowchart of FIG. In FIG. 5, ST represents a step, and the subsequent number indicates a step number. Y represents Yes and N represents No. Although not described in this flowchart, the control means 12 detects the voltage of the DC voltage output via the DC voltage detector 10, and this voltage becomes the currently set DC output voltage setting value. Thus, the switching timing of the transistor 9 and the on / off time of the transistor 9 are always controlled.

  The control means 12 first checks whether an instantaneous voltage fluctuation (temporary AC voltage drop) has occurred (ST1). As described above, this can be recognized by monitoring the peak voltage of the half cycle of the AC input voltage. When the instantaneous voltage fluctuation does not occur (ST1-N), the DC output voltage setting value is set to a standard voltage value, for example, 200 V (ST10). Then jump to ST1.

  When the occurrence of instantaneous voltage fluctuation is recognized (ST1-Y), the DC output voltage set value is lowered by one step, for example, 2V, and set to 198V (ST2). Next, “0” is stored in a counter provided in the microcomputer of the control means 12 in order to count the elapsed time when the DC output voltage set value is lowered by one step (ST3). In this embodiment, one cycle of the counter corresponds to one cycle of the input power supply frequency. However, since this counter only counts the elapsed time, any unit time may be used as long as it is shorter than the instantaneous voltage fluctuation period.

  Next, it is confirmed whether or not the instantaneous voltage fluctuation has been recovered (ST4). As described above, this can be recognized by monitoring the peak voltage of the half cycle of the AC input voltage. If it has not recovered from the instantaneous voltage fluctuation (ST4-N), it is next confirmed whether one cycle time has elapsed since the setting of the DC output voltage set value (ST5). If one cycle time has not elapsed since the setting of the DC output voltage set value (ST5-N), the process jumps to ST4.

  Next, when one cycle time has elapsed since the setting of the DC output voltage setting value (ST5-Y), "1" is added to the counter (ST6). Then, the DC output voltage set value is set by decreasing it by one step, for example, by 2V (ST7). Next, it is confirmed whether the value of the AC input voltage has decreased to the value of the operation limit voltage of the power supply device 1 and the devices connected thereto, here the air conditioner (ST8). When the value of the AC input voltage is equal to or greater than the value of the operation limit voltage (ST8-N), the process jumps to ST4.

  When the value of the AC input voltage is reduced to the value of the operation limit voltage of the power supply device 1 and the outdoor unit 20 including the power supply device (ST8-Y), the control means 12 determines that the power is actually turned off, The operation is stopped and the process of shutting off the power supply of the DC output voltage is performed (ST9). Then, all the processes are finished.

  On the other hand, when returning from the instantaneous voltage fluctuation (ST4-Y), it is next checked whether the counter is “0” (ST11). When the counter is “0” (ST11-Y), the DC output voltage setting value has also returned to the original value (standard voltage value), so the routine jumps to ST1.

  When the counter is not “0” (ST11-N), “1” is subtracted from the counter (ST12). Then, the DC output voltage set value is increased by one step, for example, increased by 2V (ST13). Then, it is confirmed whether one cycle time has elapsed since the setting of the DC output voltage set value (ST14). If one cycle time has not elapsed since the setting of the DC output voltage set value (ST14-N), the process jumps to ST14. When one cycle time has elapsed from the setting of the DC output voltage setting value (ST14-Y), it is confirmed whether or not the occurrence of instantaneous voltage fluctuation has been recognized (ST15). When the occurrence of instantaneous voltage fluctuation is not recognized (ST15-N), the process jumps to ST11. When the occurrence of the instantaneous voltage fluctuation is recognized (ST15-Y), the process jumps to ST6 and again shifts to the process of reducing the DC output voltage set value.

  As described above, when recovering from a decrease in input AC voltage due to instantaneous voltage fluctuation, inrush current to the booster circuit can be suppressed, and component destruction in the booster circuit can be prevented. In addition, since a component having a low surge current can be used as a component in the booster circuit, the cost can be reduced.

  On the other hand, the longer the period of the instantaneous voltage fluctuation, the lower the voltage of the capacitor, and the inrush current increases corresponding to this voltage when returning from the instantaneous voltage fluctuation. In the present invention, since the DC voltage set value is gradually decreased after the instantaneous voltage fluctuation occurs, the output voltage is gradually decreased even if the period during which the AC input voltage decreases due to the instantaneous voltage fluctuation is unknown. Thus, it is possible to suppress a decrease in the DC output voltage while corresponding to the generated inrush current.

  Further, since the DC voltage set value is gradually increased after recovering from the decrease in the AC input voltage due to instantaneous voltage fluctuation, the generated inrush current can be dispersed in time and the peak current can be suppressed.

  FIG. 4 is a timing chart for explaining the operation of the power supply device 1 in another embodiment. 2 and 3, FIG. 4 (1) is an AC power supply voltage, FIG. 4 (2) is a DC output voltage, FIG. 4 (3) is a DC output voltage set value, and FIG. 4 (4) is an AC input. Current, respectively. Note that the DC output voltage setting value in FIG. 4 (3) is a pseudo waveform of the setting value set in the control means 12, and is actually set by a microcomputer (not shown) in the control means 12. The value is shown. In this embodiment, the same circuit as that in FIG. 1 is used as hardware, and the control content of the control means 12 is only different from that in FIGS.

  In the processing of the control means 12 in FIG. 2 or FIG. 3, when the instantaneous voltage fluctuation is recognized, the DC output voltage set value is temporarily reduced, and then when the normal voltage recovery is recognized, the DC output is reversed. The voltage setting value is changed to the setting value before the instantaneous voltage fluctuation occurs. In the second embodiment, the AC input current is monitored, and the DC output is performed so that the inrush current due to the instantaneous voltage fluctuation does not exceed the predetermined value. The voltage setting value is set. Since this configuration is controlled only by the value of the input current regardless of the presence or absence of instantaneous voltage fluctuation, the input voltage detector 4 of FIG. 1 may be omitted.

  In FIG. 4, even if instantaneous voltage fluctuation occurs, the control means 12 controls the DC output voltage set value with the standard voltage value (200 V) as in the normal state. However, the control means 12 always detects the input current from the AC power source 2 via the input current detector 5, and the input current is limited to the input current because the instantaneous voltage fluctuation ends and the inrush current enters the capacitor 11. When the value exceeds, for example, 20 A (ampere), the control means 12 decreases the DC output voltage set value so that it is within the input current limit value. In this example, when the DC output voltage setting value is reduced to 150 V, the input current does not exceed the input current limit value: 20 A (ampere).

When the input current falls below the input current limit value, the control means 12 restores the DC output voltage set value to the standard voltage value. This operation is continued until the input current stabilizes below the input current limit value. (In practice, monitoring is always performed regardless of whether there is instantaneous voltage fluctuation.)
In this configuration, the period during which the DC output voltage setting value can be maintained at the standard voltage value can be longer than that described with reference to FIGS. 2 and 3. It is effective in the case. However, since the feedback is made after the inrush current is generated, the setting of the DC output voltage set value is delayed, and as a result, the DC output voltage may temporarily increase. Therefore, when determining the input current limit value, it is preferable to set the input current limit value to a smaller value in order to provide a slight margin.

  Next, the processing in FIG. 4 of the control means 12 will be described using the flowchart of FIG. In FIG. 6, ST represents a step, and the subsequent number indicates a step number. Y represents Yes and N represents No. Although not described in this flowchart, the control means 12 detects the voltage of the DC voltage output via the DC voltage detector 10, and this voltage becomes the currently set DC output voltage setting value. Thus, the switching timing of the transistor 9 and the on / off time of the transistor 9 are always controlled.

  First, the control means 12 checks whether the AC input current is equal to or greater than a predetermined value (input current limit value) (ST21). If the AC input current is greater than or equal to a predetermined value (ST21-Y), the DC output voltage set value is set by one step reduction, for example, 10V reduction (ST22). Again, it is confirmed whether the AC input current is equal to or greater than a predetermined value (ST23). If the AC input current is equal to or greater than the predetermined value (ST23-Y), the process jumps to ST22. As a result, a DC output voltage set value at which the AC input current becomes a predetermined value is set. In the case of FIG. 4, as a result of lowering the DC output voltage setting value so as to be the input current limit value, this value becomes 150V to 190V.

  The frequency of the AC power source 2 is 50 or 60 hertz, but the switching frequency of the transistor 9 is about several kilohertz to several tens of kilohertz, so that the DC output voltage is sufficient for the change in the input current of the AC power source 2. It can be controlled at speed.

  In FIG. 6, when the AC input current is less than or equal to a predetermined value (ST23-N), the DC output voltage set value is set by one step, for example, 10V (ST24). Next, it is confirmed whether the DC output voltage setting value is a standard voltage value, for example, 200 V (ST25). When the DC output voltage set value is the standard voltage value (ST25-Y), the process jumps to ST21. If the DC output voltage set value is not the standard voltage value (ST25-N), the process jumps to ST23.

  On the other hand, when the AC input current is equal to or smaller than the predetermined value (ST21-N), the DC output voltage set value is set to the standard voltage value (ST26). Next, it is confirmed whether the value of the AC input voltage has decreased to the value of the operation limit voltage of the power supply device 1 and the devices connected thereto, here the air conditioner (ST27). When the value of the AC input voltage is equal to or greater than the value of the operation limit voltage (ST27-N), the process jumps to ST21.

  When the value of the AC input voltage is reduced to the value of the operation limit voltage of the power supply device 1 and the outdoor unit 20 including the power supply device 1 (ST27-Y), the control unit 12 determines that the power is actually turned off, and the outdoor unit 20 Is stopped, and the process of shutting off the power supply of the DC output voltage is performed (ST28). Then, all the processes are finished.

  In this embodiment, the inrush current of the capacitor 11 is detected as the consumption current flowing in the input current detector 5. However, the present invention is not limited to this, and the current detector is arranged in series with the capacitor 11. You may make it measure the pure inrush current which flows into. In this case, since an accurate inrush current can be measured, highly accurate control can be performed.

  As described above, since the set voltage value is controlled in accordance with the input AC current corresponding to the generated inrush current, the control is easy. Further, since the necessary minimum set voltage value can be lowered, a voltage close to the standard voltage can be supplied to the load.

  In addition, by providing the power supply device described in Example 1 or Example 2 in a device such as an air conditioner, even if instantaneous voltage fluctuations occur, it is not necessary to cut off the power supply once to prevent inrush current. Continuous equipment operation is possible. For this reason, even in a device such as an air conditioner in which the compressor cannot be restarted immediately after the power is turned off, the air conditioning is not interrupted by the continuous operation, so that the comfort can be maintained.

It is a principal part block diagram which shows the Example of the outdoor unit of the air conditioner by this invention. It is a timing chart explaining the fundamental operation | movement of the 1st Example by this invention. It is a timing chart explaining the application operation | movement of the 1st Example by this invention. It is a timing chart explaining operation | movement of the 2nd Example by this invention. It is a flowchart explaining the process of 1st Example by this invention. It is a flowchart explaining the process of 2nd Example by this invention. It is a block diagram which shows the conventional power supply device. It is a timing chart explaining operation | movement with the conventional power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply device 2 AC power supply 3 Load 4 Input voltage detector (input voltage detection means)
5 Input current detector (input current detection means)
6 Bridge diode 7 Inductor 8 Diode 9 Transistor 10 DC voltage detector 11 Capacitor 12 Control means 20 Outdoor unit 31 Inverter 32 Motor

Claims (1)

Input voltage detection means for detecting an input AC voltage, a booster circuit for boosting a DC voltage obtained by rectifying the AC voltage and supplying the output voltage to a load, an output voltage detection means for detecting the output voltage, Control means for inputting detection results of the input voltage detection means and the output voltage detection means and controlling the output voltage value of the booster circuit to be a set voltage value which is a voltage value targeted for control; ,
The control means reduces the set voltage value stepwise as time passes when the AC voltage becomes a predetermined voltage or less, and sets the set voltage when the AC voltage becomes the predetermined voltage or more. A power supply apparatus, wherein the value is returned to a value before the AC voltage becomes equal to or lower than the predetermined voltage.

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