JP3726611B2 - Air conditioner power circuit - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a power supply circuit of an air conditioner and its control.
[0002]
[Prior art]
Conventionally, various rectification methods using diodes are known. FIG. 18 shows an example of a full-wave rectifier circuit using a bridge rectifier circuit also used in an air conditioner.
[0003]
FIG. 18A shows the flow of current when the alternating current from the alternating current power source 1 is in the positive half cycle. As indicated by the arrows, the current flows in the order of the diode 3, the smoothing capacitor 7, and the diode 4, and the positive voltage Vo can be taken out.
[0004]
FIG. 18B shows the flow of current during the negative half cycle of alternating current from the alternating current power source 1. As indicated by the arrows, the current flows in the order of the diode 5, the smoothing capacitor 7, and the diode 2, and the positive voltage Vo can be taken out.
[0005]
As described above, the current waveform is as indicated by L3 in FIG. 19, and the AC from the AC power source 1 is rectified during both the positive half cycle and the negative half cycle, and a positive DC voltage can be obtained.
[0006]
[Problems to be solved by the invention]
However, in the conventional power supply circuit as described above, since the input current flows only during a period when the voltage of the AC power supply is higher than the DC voltage, there is a problem that the power factor at light load is low and the harmonics are large. It was.
[0007]
Normally, a method of connecting a reactor between an AC power supply and a bridge rectifier circuit is used as a proposal for improving harmonics. However, with this method, a power factor of only about 70% can be obtained even if harmonics can be suppressed. There was a problem.
[0008]
The present invention solves such a conventional problem, and connects a capacitor via an opening / closing means between an AC terminal and a DC terminal of a bridge rectifier circuit, and controls the opening / closing means. It is an object of the present invention to provide a power supply circuit that can achieve both efficiency and harmonic suppression.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention comprises an AC power supply, a bridge rectifier circuit comprising four diodes for full-wave rectification of the AC power supply, and a capacitor at a DC output terminal of the bridge rectifier circuit, An AC power source; a reactor connected between the bridge rectifier circuit; an opening / closing means and a capacitor connected in series between an AC input terminal and a DC output terminal of the bridge rectifier circuit; and a load detection means. And opening / closing means is controlled according to the load detection means.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
(Embodiment 1)
FIG. 1 shows a power supply circuit configuration of the air conditioner according to Embodiment 1.
[0012]
The AC power source 1 shown in FIG. 1 is 200 VAC, and the power source includes a bridge rectifier circuit 6 composed of four diodes 2 to 5 and a load 8 connected in parallel with a smoothing capacitor 7. The AC input terminal is connected to the AC power source 1 through the reactor 9, and an opening / closing means 10 and a capacitor 11 are connected in series between the other AC input terminal and the negative output terminal of the bridge rectifier circuit 6. 10, a diode 12 is connected in parallel so that the forward direction is from the negative input side to the negative input side.
Further, at both ends of the smoothing capacitor 7, voltage detection means 13 constituted by a voltage dividing resistor or the like is provided for detecting a DC voltage, and is connected to the comparison means 14. In the comparison means 14, the detection voltage in the voltage detection means 13 and a reference voltage composed of a resistor, a constant voltage diode or the like are compared by a comparator 15 such as a comparator. The output of the comparison means 14 is connected to an opening / closing drive means 16 that drives the opening / closing means 10.
[0013]
The reactor 9 is relatively large at about 5 to 10 mH for suppressing harmonics, and the capacitor 11 connected to the switching means 10 is as small as about 1/50 to 1/100 of the smoothing capacitor 7.
[0014]
FIG. 2 shows a current waveform when the switching means 10 is turned on in the circuit of FIG. In the figure, L1 represents a power supply voltage and L2 represents a current waveform. In normal full-wave rectification, when the AC power source 1 is in a negative half cycle, the voltage of the smoothing capacitor 7 is lower than the voltage of the AC power source 1 near the phase zero, so no current flows, but in the circuit of the present invention, A current flows from the capacitor 11 through the diode 2 and the reactor 9. This current continues to flow until the capacitor 11 is charged to a voltage lower than the rectified voltage of the AC power supply 1 by the forward voltage VF of the diode 2. Thereafter, when the voltage of the AC power supply 1 rises and reaches the voltage of the smoothing capacitor 7 or more, a charging current starts to flow to the smoothing capacitor 7 through the capacitor 5.
[0015]
Next, when the AC power supply 1 is in a positive half cycle, the voltage of the capacitor 11 is superimposed on the voltage of the AC power supply 1, so that the smoothing capacitor 7 and the load 8 pass from the AC power supply 1 through the diode 3 even near the phase zero. Current flows into the. As described above, the circuit according to the present invention allows a current to flow from the zero phase of the AC voltage regardless of whether the alternating current from the AC power source 1 is a positive half cycle or a negative half cycle, thereby increasing the power factor. Can be planned. Further, since this current is a series resonance current between the reactor 9 and the capacitor 11, the waveform thereof is smooth and sufficiently satisfies the harmonic regulation.
[0016]
As described above, the power supply circuit of the present invention is a power supply in which the current waveform is improved when the load 8 is larger than a certain level, and both harmonics and power factor are compatible. However, when the load is light, that is, when the energy of the electric charge charged in the capacitor 11 is not consumed by the load 8 by the next half cycle of the AC power supply 1, the voltage of the smoothing capacitor 7 gradually increases, and finally It reaches the same DC voltage as that during voltage doubler rectification.
[0017]
In a normal air conditioner, a compressor and a fan motor are the main loads, but their drive voltage is about 300 to 400V or less. On the other hand, when the circuit of the present invention is used at AC 200 V, the boosting effect by the reactor 9 is also added, and the DC voltage after smoothing exceeds about 600 V at the maximum. Therefore, when the switching means 10 is kept on from the heavy load to the light load, the required withstand voltage of the smoothing capacitor 7 becomes larger than necessary.
[0018]
Furthermore, at the time of a light load, the charge / discharge current to the capacitor 11 becomes larger than the charge / discharge current to the smoothing capacitor 7 that is seen at the time of normal full-wave rectification, and the power factor decreases. In such a case, the fact that the DC voltage is increased as described above is utilized, the comparison means 14 compares the voltage detection means 13 with the reference voltage, and the DC voltage exceeds the preset overvoltage limit value. In such a case, control to turn off the opening / closing means 10 is performed.
[0019]
Here, the diode 12 is connected in parallel with the switching means 10 in such a direction that a discharge path can be secured in order to discharge the charge accumulated in the capacitor 11 when the switching means 10 is turned off.
[0020]
When the opening / closing means 10 is off, the operation of this circuit is the same as that of a normal full-wave rectifier circuit. Even when the opening / closing means 10 is off, the reactor 9 is inserted on the AC side in the circuit of the present invention, so that the harmonic components are suppressed and the harmonic regulation is sufficiently met.
[0021]
As described above, by providing an overvoltage limit value and turning off the switching means at the time of a light load where the DC voltage becomes high, it is possible to supply a power source corresponding to harmonics with a high power factor from light load to heavy load. it can.
[0022]
(Embodiment 2)
A power supply circuit in which the overvoltage limit value described in the first embodiment is set lower than the DC voltage after rectification at no load will be described with reference to FIG.
As described in the first embodiment, the power supply circuit of the present invention has a voltage limit mechanism that turns off the switching means 10 when the DC voltage rises excessively in order to prevent an excessive voltage rise at light load. However, by setting the overvoltage limit value to be lower than the DC voltage after rectification at no load, the opening / closing means 10 can be prevented from being turned on at a light load that is preferably turned off. That is, in the case of no load, the DC voltage is equal to or higher than the overvoltage limit value, and the switching means 10 is turned off. Even if the load gradually increases, the switching means 10 is kept off until the DC voltage becomes lower than the set voltage.
[0023]
Therefore, at the time of light load, the opening / closing means 10 is maintained off, so there is no loss for opening / closing the opening / closing means 10 and the efficiency is improved as compared with the first embodiment.
Further, the comparison means 14 has no hysteresis, and the DC voltage is substantially kept at the set limit voltage while the switching means 10 is repeatedly turned on and off at light to medium loads. When the load further increases, the opening / closing means 10 is turned on.
From the above, FIG. 3 shows an example of the load-DC voltage characteristics when the set voltage value of the voltage limit is set to 260 V in the second embodiment. In the figure, M5 represents a region where the opening / closing means 10 is repeatedly turned on and off, and the DC voltage is maintained at about DC 260 V as the center by changing the ratio of on and off.
[0024]
In the circuit according to the second embodiment, when the opening / closing means 10 changes from on to off or from off to on, it always changes through the repeated on / off state, and therefore, the DC generated when the opening / closing means 10 is switched. A change in voltage can be avoided. Further, since the influence on the ripple of the DC voltage in a state where the opening / closing means 10 is repeatedly turned on and off is as small as several volts, there is almost no influence on the load.
[0025]
(Embodiment 3)
The configuration of the power supply circuit according to Embodiment 3 is shown in FIG.
[0026]
When the switching means 10 is in the on state, the DC voltage is increased by several tens of volts in the same load state, depending on the capacitance of the capacitor 11, due to the boosting effect by the reactor 9, as compared with the off state. Therefore, when the state of the opening / closing means 10 changes, the DC voltage changes by several tens of volts within a period of several power supply cycles.
[0027]
In view of the above, in the configuration of the third embodiment, the overvoltage limit value is detected using the first reference voltage and the second reference voltage set about 40 to 50 V higher than the first reference voltage. When the DC voltage is equal to or lower than the first reference voltage, the switching means 10 is turned on, and when the DC voltage is equal to or higher than the second reference voltage, the switching means 10 is turned off to give the comparison means 14 hysteresis characteristics. As a result, even if the DC voltage rises when the switching means 10 is turned on, the second reference voltage is not exceeded due to the voltage rise that occurs, so the switching means 10 remains on and uses a single reference voltage. Unlike the case where the switching means 10 is turned on, the voltage rises, and the hunting phenomenon in which the switching means 10 is repeatedly turned on / off, such as the switching means 10 being turned off again by an overvoltage limit, does not occur.
[0028]
FIG. 5 shows the load-voltage characteristics in the first embodiment. In the figure, M1 represents a characteristic when the opening / closing means 10 is on, and M2 represents a characteristic when the switching means 10 is off. As described above, since the comparison unit 14 has a hysteresis characteristic, when the load gradually increases, it changes from M2 → M3 → M1, and conversely, when it becomes lighter, M1 → M4 → M2. And change.
As described above, it is possible to provide a power supply circuit that suppresses harmonics and realizes a high power factor regardless of the weight of the load by turning on and off the switching means 10 according to the magnitude of the voltage of the smoothing capacitor 7. Can do.
[0029]
(Embodiment 4)
FIG. 6 shows a power supply circuit configuration of the air conditioner according to the fourth embodiment.
[0030]
In addition to the power supply configuration of the first embodiment, current detection means 17 configured by a current transformer or the like for detecting current from an AC power supply is inserted in the AC line, and its output is connected to the control means 18. ing.
[0031]
Control is performed to turn on the switching means 10 when the input current detected by the current detector 17 exceeds the set current. Therefore, during the light load, since the input current of the AC power supply 1 is small, the switching means 10 is turned off. However, when the load becomes heavy and the input current increases, the switching means 10 is turned on.
[0032]
Since the input current and the magnitude of the load correspond approximately one to one, by performing this control, the magnitude of the load is judged almost accurately by the current, and the switching means 10 is turned off at light load. Is possible.
[0033]
The detected current may be controlled using a DC current supplied to the load instead of the input current.
[0034]
Further, the control means 18 may be the comparison means 14 constituted by a comparator or the like as in the first embodiment.
[0035]
(Embodiment 5)
FIG. 7 shows a power supply circuit configuration applied to an outdoor unit of an air conditioner.
[0036]
The main load of the air conditioner is the compressor 19, and the rotational speed of the compressor 19 is controlled by the indicated rotational speed output from the control means 18.
[0037]
In order to detect the current rotational speed of the compressor 19, the rotational speed detection means 20 takes out a signal for detecting the motor magnetic pole position in the compressor 19, and the controller 19 detects the timing of the detection signal and its time. The current rotational speed of the compressor 19 is calculated from the change.
Since the compressor 19 occupies most of the load of the air conditioner, it can be considered that the air conditioner is in a light load state when the rotation speed of the compressor 19 is low. Therefore, the control to turn on the opening / closing means 10 is performed only when the rotation speed of the compressor 19 is higher than the preset rotation speed.
[0038]
Depending on the operating condition of the air conditioner, such as during de-icing, the load may be reduced even though the rotational speed of the compressor 19 is large. In preparation for such a case, in the first embodiment, It is effective to have a mechanism for turning off the switching means 10 using the DC voltage limiter mechanism mentioned above. In this case, the comparison means 14 used for the voltage limiter may or may not have hysteresis.
[0039]
As described above, by controlling the opening / closing means 10 in accordance with the rotational speed of the compressor 19, it is possible to provide a power source that suppresses harmonics with a high power factor in a wide range of air conditioner load conditions. It becomes.
[0040]
(Embodiment 6)
Similarly, the power supply circuit and control in the outdoor unit of the inverter air conditioner having the compressor 19 as a load will be described with reference to FIG.
Here, the AC power source 1 represents a commercial power source connected to the indoor unit via an internal / external connection wire.
[0041]
In the inverter air conditioner, the target rotational speed of the compressor 19 is determined on the basis of the difference between the set temperature and the current indoor temperature. The control means for each time step in the control with respect to the target rotational speed thus determined. At 18, the indicated rotational speed of the compressor 19 is determined.
[0042]
The indicated rotational speed is determined by determining the amount of increase / decrease in the rotational speed for each time step from the difference between the target rotational speed and the current compressor rotational speed and the current rotational speed of the compressor. Further, the calculation is performed by adding the rotation speed increase / decrease amount for each step to the command rotation speed. The reason for determining the indicated rotational speed from the target rotational speed is to prevent the compressor 19 from stepping out.
[0043]
The compressor 19 is driven by the compressor drive means 21 so that the compressor 19 rotates at the commanded rotational speed calculated in this way. If the commanded rotational speed is greater than the set rotational speed, the load is increased. The opening / closing means 10 is turned on because it is considered sufficiently heavy. If it is smaller than the set number of revolutions, it is regarded as a light load, and the opening / closing means 10 is turned off.
[0044]
FIG. 8 shows the relationship between the rotational speeds when the target rotational speed is N2 when the compressor 19 rotates at the rotational speed N1, and FIG. 9 shows a control flowchart.
[0045]
If controlled in this way, the target rotational speed does not change complicatedly under conditions where there is no sudden temperature change or temperature setting change, and the indicated rotational speed monotonously increases or decreases. Without repeating opening and closing, it is possible to avoid a hunting phenomenon in which the rotation speed of the compressor 19 as a load repeatedly overshoots.
In addition, since the load state is determined by using the indicated rotational speed that is closer to the actual compressor rotational speed than the target rotational speed, even when the target rotational speed is high and the load is light, the opening / closing means It is possible to turn on the opening / closing means 10 after the load has increased to some extent without turning on the switch 10.
[0046]
(Embodiment 7)
FIG. 10 shows a configuration of a power supply circuit according to the seventh embodiment. The power supply circuit of the seventh embodiment has a power supply phase detection circuit 22 that detects the phase of the AC power supply 1.
[0047]
The controller 19 opens and closes an opening / closing means control signal 23 in which the deviation of the on-timing is adjusted so that the opening / closing means 10 is turned on after several hundred μs to several ms has elapsed with respect to the detected zero phase of the AC power supply 1. Tell to means 16. FIG. 11 shows an example of the opening / closing means control signal 23.
[0048]
Note that the time from the zero phase timing of the AC power supply 1 to turning on the switching means 10 is set in advance based on the power supply rotation speed of the AC power supply 1 and the detected value of the load state represented by power supply current, DC voltage, etc. Select the time set with.
[0049]
If controlled in this way, the amount of charge charged / discharged by the capacitor 11 during one cycle of the AC power supply 1 varies depending on the length of time ΔT from the zero phase timing until it is turned on, and therefore, ΔT has several differences. Having the length data makes it possible to control the DC voltage by selecting ΔT.
[0050]
Therefore, if this control is used when the switching means 10 is on, the DC voltage can be kept low even during light loads.
[0051]
(Embodiment 8)
FIG. 12 shows the control timing of the switching means in the power supply circuit according to the eighth embodiment.
[0052]
The power supply circuit of the present invention performs switching of the switching means 10 in order to improve the power factor and harmonics over a wide range. At that time, depending on the presence or absence of the action of the booster circuit composed of the reactor 9, the diode 2, and the capacitor 11. A phenomenon occurs in which the DC voltage changes by several tens of volts during several power supply cycles.
[0053]
In this case, when the compressor 19 as a load is a DC motor, the rotational speed changes because the DC voltage changes. In particular, when the voltage rises, if the speed of increase in the rotation speed of the compressor 19 cannot follow the rise in voltage, there is a risk that the winding current of the motor will rise, so a rapid voltage rise is not preferable. .
[0054]
In order to improve the above problem, in the present embodiment, the ON timing of the opening / closing means control signal 23 sent from the control unit 19 to the opening / closing drive means 16 is delayed from the negative zero phase of the AC power supply 1. If the delay amount ΔT from the zero phase to the on-timing is changed, the charge amount of the capacitor 11 in the negative half cycle of the power supply changes. By changing the charge amount, the discharge amount in the next positive half cycle can be changed, and as a result, the voltage change amount in one cycle of the power source can be suppressed.
[0055]
Accordingly, when the switching means 10 is switched, the delay amount of the ON timing of the switching means control signal 23 is gradually changed as ΔT1 and ΔT2 (ΔT1> ΔT2), and finally ΔT is set to zero, so that the DC voltage The change speed can be suppressed, and the opening / closing means 10 can be switched smoothly.
[0056]
(Embodiment 9)
FIG. 13 shows a control timing waveform of the opening / closing means 10 according to the ninth embodiment.
[0057]
FIG. 13 shows a case where the opening / closing means 10 is changed from OFF to ON according to the change of the load 8.
[0058]
The opening / closing means control signal 23 is initially turned on for a negative half cycle and turned off. In the positive half cycle, since there is the diode 12, the electric charge of the capacitor 11 is discharged regardless of the state of the switching means 10, so that the current waveform is the same as when the switching means 10 is on, resulting in opening and closing for one cycle. The current waveform is obtained when the means 10 is on.
After the opening / closing means 10 is turned off for a period corresponding to the next three cycles, the opening / closing means 10 is turned on again for a half cycle, and the voltage that has decreased while the opening / closing means 10 is turned off begins to rise again.
[0059]
Further, the switching means 10 is synchronized with the power supply frequency by using the power supply phase detection means 20 for detecting the phase of the AC power supply 1, and the current waveform for one cycle of the power supply or an integral multiple of the off period thereof, While repeating the current waveform in the ON period for one cycle of the power supply, the voltage change during switching of the switching means 10 is suppressed by gradually changing the ON ratio.
[0060]
By this control, the voltage rise at the time of switching of the opening / closing means 10 is suppressed to about the voltage charged in the capacitor 11 in one half cycle of the power supply, and therefore the voltage rise rate is several times compared to the first embodiment. It becomes possible to make it about 1 / min.
[0061]
(Embodiment 10)
FIG. 14 shows a power supply circuit configuration according to the tenth embodiment.
[0062]
The first opening / closing means 24 and the first capacitor 25 are connected in series, and in parallel therewith, the second opening / closing means 26 and the second capacitor 27 are connected in series. Further, similarly to the first embodiment, the first opening / closing means 28 and the second opening / closing driving means 29 are provided. The rest of the configuration is the same as in the first embodiment, and a description thereof will be omitted.
[0063]
As described in the first embodiment, when the opening / closing means 10 is turned on at a light load, the power factor is reduced, but the magnitude of the load at which the power factor starts to decrease varies depending on the size of the capacitor 11. The relationship is shown in FIG.
[0064]
In the circuit of the present invention, it is effective to increase the capacity of the capacitor 11 in order to ensure a DC voltage at the time of heavy load. However, when the capacitor 11 is increased, the power factor decreases. May cause the power factor at medium load to be kept high.
[0065]
Therefore, switching the capacity of the capacitor 11 to change the capacity of the capacitor 11 during medium load and heavy load is an effective means for maintaining a high power factor during light to medium loads.
[0066]
The first opening / closing means 24 and the second opening / closing means 26 are both controlled based on the same load detection means expressed by voltage, current, or the rotational speed of the compressor, and the first opening / closing means at light load. Both the means 24 and the second opening / closing means 26 are turned off, only the first opening / closing means 24 is turned on during an intermediate load, and both the first and second opening / closing means 24, 26 are turned on during a heavy load.
[0067]
As described above, a circuit configuration having a smaller capacitor capacity at the time of medium load than at the time of heavy load can be taken, and a high power factor can be obtained.
[0068]
In addition, when the load is heavy, the capacitor capacity can be increased and a DC voltage can be secured.
[0069]
As described above, the voltage change at the time of switching of the switching means becomes three stages. Therefore, by appropriately selecting the capacities of the first capacitor 25 and the second capacitor 27, the first switching means and the second switching means The voltage change at the time of on / off switching can be reduced and a smooth transition effect can be expected, and harmonic suppression and higher power factor can be realized in a wider range of load conditions.
[0070]
(Embodiment 11)
FIG. 16 shows a circuit configuration of a power supply according to the eleventh embodiment.
[0071]
The reactor 9 includes an intermediate tap 30, and the inductance can be changed by the third opening / closing means 31 connected to the intermediate tap 30.
[0072]
In the circuit of the present invention, a reactor having a relatively large inductance is used to suppress harmonics. Therefore, in an air conditioner of 4 kW, 5 kW or more, the voltage drop in the reactor 9 increases as the current increases. As a result, the DC voltage drops, and there may be a case where a DC voltage sufficient to drive the compressor 19 cannot be obtained.
In such a case, by turning on the third opening / closing means 31 under heavy load, it is possible to reduce the voltage drop by reducing the inductance and to secure the DC voltage.
[0073]
(Embodiment 12)
FIG. 17 shows a configuration of a circuit in which the switching means 10 and the diode 12 of the third embodiment are replaced with a MOSFET 32 and the switching drive means 16 is replaced with a gate drive circuit 33 as a twelfth embodiment.
[0074]
Since a parasitic diode exists in the MOSFET 32, the number of parts is reduced by using it instead of the switching means 10 and the diode 12 connected in parallel thereto. The circuit can be reduced in size and price.
In addition, since there is no mechanical contact, the advantage in terms of life is increased.
[0075]
【The invention's effect】
As is apparent from the above embodiment, according to the first aspect of the present invention, the reactor, the capacitor, and the switching means are connected to the full-wave rectifier circuit, the smoothed voltage is detected, and the full voltage rectifier circuit is opened and closed by the overvoltage limiter at light load. By turning off the means, it is possible to supply a power source that achieves both suppression of harmonics and high power factor over a wide range from light load to heavy load.
[0076]
According to the second aspect of the present invention, it is desirable to turn off the opening / closing means in terms of power factor and efficiency by setting the set value of the overvoltage limiter to be equal to or lower than the rectified voltage of the power supply during no load. The opening / closing means can be automatically turned off when a load is applied. In addition, since there is no sudden change in the DC voltage due to opening / closing of the opening / closing means, it is possible to continuously and smoothly change the DC voltage with respect to load fluctuations.
[0077]
According to the third aspect of the present invention, when the overvoltage limiter has a hysteresis characteristic and the amount of hysteresis is set to be equal to or greater than the fluctuation of the DC voltage generated when the switching means is opened and closed, the switching means is switched. In addition, it is possible to prevent the hunting phenomenon that the DC voltage is not stabilized by repeatedly opening and closing.
[0078]
According to the fourth aspect of the present invention, by controlling the opening / closing means with current, it is possible to determine the weight of the load almost correctly and control the opening / closing means.
[0079]
Further, according to the fifth aspect of the present invention, the opening / closing means is opened / closed according to the rotational speed of the compressor of the air conditioner, so that the opening / closing means can be opened at a light load where the voltage may actually increase. The opening / closing means can be controlled without being turned on.
[0080]
According to the sixth aspect of the present invention, by controlling the opening / closing means at the indicated rotational speed of the compressor, it is possible to prevent the rotational speed of the load from hunting due to a voltage change at the time of switching of the opening / closing means. be able to. Furthermore, by opening and closing the opening / closing means using the indicated rotational speed that takes a value close to the actual rotational speed, it is possible to supply power to prevent load hunting while determining the weight of the load almost correctly.
[0081]
Furthermore, according to the seventh aspect of the present invention, it is possible to control the voltage of the load by changing the length of the on-time of the switching means and the start timing.
[0082]
According to the eighth aspect of the invention, the ON signal of the opening / closing means has a width representing the duty, and the ON timing and the width thereof are gradually changed, so that the voltage changing speed when switching the opening / closing means is reduced. It becomes possible to do.
[0083]
According to the ninth aspect of the present invention, the rate of change of the voltage at the time of switching the switching means can be reduced by gradually changing the ON / OFF ratio of the switching means with the power supply half cycle as a basic unit. it can.
[0084]
Furthermore, according to the invention of claim 10, smooth switching can be performed by performing switching in three stages using two sets of opening / closing means, and over a wider range.
A power circuit that can meet high power factor and high frequency regulation can be supplied.
[0085]
According to the invention of claim 11, the intermediate tap is provided in the reactor, and the opening / closing means is provided between the intermediate tap and one end of the reactor, so that the opening / closing means is turned off during light to medium loads, and during heavy loads. By turning on the opening / closing means, it is possible to secure a DC voltage at the time of heavy load, and to supply power that can handle a wider range of loads.
[0086]
According to the invention of claim 12, by using the MOSFET instead of the switching means and the diode, the number of parts can be reduced and a simple configuration can be achieved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a power supply circuit of an air conditioner according to the present invention.
FIG. 2 is a current waveform diagram in the first embodiment.
FIG. 3 is a load-voltage characteristic diagram according to the second embodiment.
FIG. 4 is a configuration diagram of Embodiment 3.
FIG. 5 is a load-voltage characteristic diagram according to the third embodiment.
FIG. 6 is a configuration diagram of a fourth embodiment.
FIG. 7 is a configuration diagram of a fifth embodiment and a sixth embodiment.
FIG. 8 is a relationship diagram of each rotation speed related to compressor control.
FIG. 9 is a flowchart of control in the sixth embodiment.
FIG. 10 is a block diagram of a seventh embodiment.
11 is an explanatory diagram of an opening / closing means control signal in Embodiment 7. FIG.
FIG. 12 is an explanatory diagram of the control timing and current waveform of the switching means in the eighth embodiment.
FIG. 13 is an explanatory diagram of control timing and current waveforms of the switching means in the ninth embodiment.
14 is a configuration diagram of Embodiment 10. FIG.
FIG. 15 is a graph showing load-power factor characteristics in the power supply circuit of the present invention.
FIG. 16 is a configuration diagram of the eleventh embodiment.
FIG. 17 is a block diagram of a twelfth embodiment.
FIG. 18 is a power circuit configuration diagram of a conventional air conditioner
FIG. 19 is a current waveform diagram in a power supply circuit of a conventional air conditioner.
[Explanation of symbols]
1 AC power supply
2 Diode
3 Diode
4 Diode
5 Diode
6 Bridge rectifier circuit
7 Smoothing capacitor
8 Load
9 Reactor
10 Opening and closing means
11 Capacitor
12 diodes
13 Voltage detection means
14 Comparison means
15 comparator
16 Opening and closing drive means
17 Current detection means
18 Control means
19 Compressor
20 Rotational speed detection means
21 Compressor drive means
22 Power supply phase detection means
23 Control means control signal
24 First opening / closing means
25 First capacitor
26 Second opening / closing means
27 Second capacitor
28 First opening / closing drive means
29 Second opening / closing drive means
30 Middle tap
31 Third opening / closing means
32 MOSFET
33 Gate drive circuit

Claims (12)

An AC power source, a bridge rectifier circuit composed of four diodes for full-wave rectification of AC from the AC power source, a smoothing capacitor connected between DC outputs of the bridge rectifier circuit, the AC power source and the bridge A reactor connected between the AC input terminal of the rectifier circuit; an opening / closing means and a capacitor connected in series between one AC input terminal and one DC output terminal of the bridge rectifier circuit; A diode connected in parallel to the means, a voltage detection means for detecting the voltage across the smoothing capacitor, and a comparison means for comparing the detection voltage in the voltage detection means with a reference voltage. A power supply circuit for an air conditioner characterized in that the switching means is turned on when the voltage becomes lower than the reference voltage, and the switching means is turned off when the voltage becomes higher than the reference voltage. The reference voltage of the comparison means is set to a voltage lower than the peak value of the DC voltage when the AC power supply is full-wave rectified at no load, and the detection voltage in the voltage detection means is higher than the reference voltage 2. The power supply circuit according to claim 1, wherein the switching means is turned off and the switching means is turned on when the voltage is lower than a reference voltage. The reference voltage of the comparison means is composed of a first reference voltage and a second reference voltage set higher than the first reference voltage, and the detection voltage in the voltage detection means is higher than the first reference voltage. A power supply circuit having hysteresis characteristics in which the switching means is turned on when the voltage becomes lower and the switching means is turned off when the voltage becomes higher than the second reference voltage, and the difference between the first reference voltage and the second reference voltage 2. The power supply circuit according to claim 1, wherein is greater than a change amount of a DC voltage generated when the opening / closing means is opened / closed. An AC power source, a bridge rectifier circuit composed of four diodes for full-wave rectification of AC from the AC power source, a smoothing capacitor connected between DC outputs of the bridge rectifier circuit, the AC power source and the bridge A reactor connected between the AC input terminal of the rectifier circuit, a capacitor connected in series with the switching means between one AC input terminal and the other DC output terminal of the bridge rectifier circuit, and the switching means A diode connected in parallel with each other, a current detection means for detecting a power supply current or a DC current of the load, and a comparison means for comparing a current detected by the current detection means with a set current, which is detected by the current detection means A power supply circuit for an air conditioner, wherein the opening / closing means is turned on when the applied current is larger than a set current. A compressor, a rotational speed detection means for detecting the rotational speed of the compressor, and a control for calculating an indicated rotational speed of the compressor from a difference between an actual rotational speed detected by the rotational speed detection means and a target rotational speed; And an air conditioner for controlling the rotation speed of the compressor, the compressor driving means for driving the compressor to rotate the compressor at the indicated rotation speed,
An AC power source, a bridge rectifier circuit composed of four diodes for full-wave rectification of AC from the AC power source, a smoothing capacitor connected between DC outputs of the bridge rectifier circuit, the AC power source and the bridge A reactor connected between the AC input end of the rectifier circuit, an opening / closing means and a capacitor connected in series between one AC input end and one DC output end of the bridge rectifier circuit, and the opening / closing means And a diode connected in parallel, and when the rotation speed of the compressor detected by the rotation speed detection means is larger than a set rotation speed, the opening / closing means is turned on. Power supply circuit. Control for calculating the indicated rotational speed of the compressor from the target rotational speed and the difference between the compressor, the rotational speed detecting means for detecting the rotational speed of the compressor, and the actual rotational speed detected by the rotational speed detecting means And an air conditioner for controlling the rotation speed of the compressor, the compressor driving means for driving the compressor to rotate the compressor at the indicated rotation speed,
An AC power source, a bridge rectifier circuit composed of four diodes for full-wave rectification of AC from the AC power source, a smoothing capacitor connected between DC outputs of the bridge rectifier circuit, the AC power source and the bridge A reactor connected between the AC input end of the rectifier circuit, an opening / closing means and a capacitor connected in series between one AC input end and one DC output end of the bridge rectifier circuit, and the opening / closing means And a diode connected in parallel to the air conditioner, wherein the opening / closing means is turned on when the indicated rotational speed of the compressor calculated by the control means is larger than the set rotational speed. circuit. Power supply phase detection means for detecting the phase of the AC power supply, and for each power supply cycle of the AC power supply, the opening / closing means for a certain period from the time when the AC power supply detected by the power supply phase detection means becomes zero phase. A control means for turning on the opening / closing means after being kept off, and adjusting a DC voltage supplied to the load by changing a period during which the opening / closing means is kept off within a range from zero to a power cycle. The power supply circuit according to any one of claims 3 to 6, wherein: The control means sets in advance a time from when the AC power supply detected by the power supply phase detection means becomes zero phase to when the opening / closing means is turned on when switching the opening / closing means from OFF to ON. The rising speed of the DC voltage generated when switching the switching means is suppressed by gradually changing the period from the initial time to the power supply cycle of the AC power supply and gradually reducing it to zero. Item 8. A power supply circuit for an air conditioner according to Item 7. The control means, when switching the opening and closing means from OFF to ON state, alternately turning on the opening and closing means for a plurality of cycles after turning on the opening and closing means for one cycle of the AC power supply, By gradually decreasing the period for turning off the opening / closing means from a preset number of cycles, the period for turning off the opening / closing means is finally eliminated, thereby suppressing the rate of increase in DC voltage when switching the opening / closing means. The power supply circuit according to claim 3, wherein: A first switching means and a first capacitor connected in series between one AC input terminal and one DC output terminal of the bridge rectifier circuit, and a first switching circuit connected in parallel to the first switching circuit. 1 diode, a second switching means and a second capacitor connected in series, and a second diode connected in parallel with the second switching means, the first switching means and the second A power supply circuit connected so that the first capacitor and the second capacitor are connected in parallel when the switching means of
Load detection means for detecting the voltage across the smoothing capacitor, the indicated rotational speed of the compressor or the actual rotational speed of the compressor, and comparison means or control for comparing the output of the load detection means with a preset value The first opening / closing means and the second opening / closing means are both turned off at a light load, and only the first opening / closing means is at a middle load by comparing the output of the load detection means with a preset value. 10. The air conditioner power supply circuit according to claim 3, wherein both the first opening / closing means and the second opening / closing means are turned on when the load is heavy. The reactor includes an intermediate tap, and includes a third opening / closing means connected between the intermediate tap and either end of the reactor, and the load detection means,
The power supply circuit according to any one of claims 3 to 9, wherein the third opening / closing means is turned on at a light load, and the third opening / closing means is turned off at a heavy load. 12. The power supply circuit according to claim 1, wherein at least one of the opening / closing means and the diode connected in parallel to the opening / closing means are configured by MOSFETs.

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