JP2000125545A - Dc power unit and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the rate of a processing for control, improve power factor, reduce harmonics and reduce cost by reducing the number of switching times and setting it to be the required minimum. SOLUTION: A DC power unit is provided with a rectifying circuit 2 which rectifies the voltage of AC power 1, a smoothing capacitor 4 for smoothing output voltage compared to the rectifying circuit 2, a switch means 6 arranged on an AC power 1-side compared to the smoothing capacitor 4, a reactor 3 arranged to the power-side compared to a switching means 6, a load quantity detection means 10 for detecting the load quantity of a load connected to the smoothing capacitor 4 connected in parallel and a control means 8 for controlling the opening/closing of the switching means 6 at opening/closing time corresponding to load quantity at least twice in a power half period in synchronization with the power period of AC power 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply used for an air conditioner, etc.
The present invention relates to a DC power supply device that suppresses harmonics so as to generate an amount equal to or less than a limit value of a harmonic regulation.

[0002]

2. Description of the Related Art FIG.
FIG. 7 is a block diagram illustrating a configuration of a conventional DC power supply device disclosed in Japanese Patent Publication No. 7-No. In the figure, 1 is an AC power supply, 2 is a rectifier circuit for full-wave rectification of the voltage of the AC power supply 1, 7 is a load, 33
Is a transformer provided on the output side of the rectifier circuit 2 via the smoothing capacitor C1, and 34 is a primary coil L of the transformer 33.
A field effect transistor (hereinafter referred to as an FET) for controlling the voltage applied to 1; 35, a first comparator for comparing the voltage applied to the load 7 with the reference voltage Vref; 36, a triangular wave for generating and outputting a triangular wave A generator 37 for comparing the result of the first comparator 35 with the triangular wave output from the triangular wave generator 36;
A driver that outputs a drive pulse to the gate of the FET 34 based on the output from the comparator 37, and a line filter 39 that removes noise on the voltage supplied from the AC power supply 1 and outputs the noise to the rectifier circuit 2. is there.

Next, the operation of the conventional DC power supply will be described. The first comparator 35 detects a voltage corresponding to the current flowing through the load 7, compares the detected voltage with the reference voltage Vref, and outputs the difference to the second comparator 37. Second comparator 3
Reference numeral 7 compares the difference output from the first comparator 35 with the triangular wave of the triangular wave generator 36, and switches the FET 34 with a drive pulse having a pulse width determined according to the detected voltage, thereby smoothing and stabilizing the FET 34. DC voltage is load 7
Supplied to

[0004]

In the above-described conventional DC power supply device, when the switching operation of the FET 34 is performed at a constant cycle, the output voltage changes depending on the load amount. The first comparator 35 compares the difference between the first comparator 35 and the triangular wave of the triangular wave generator 36 with the reference voltage, and the second comparator 37 compares the difference between the first comparator 35 and the triangular wave. FET3 according to the detected voltage
Although the ratio of the pulse width of the drive pulse for switching 4 is changed, it is necessary to always perform feedback control because the output voltage is significantly increased if the load variation of the load 7 becomes too large. There was a problem. Here, if this DC power supply is applied to a model with a wide range of operation, such as an air conditioner, where the load changes, the output voltage will increase significantly, and parts with a high withstand voltage must be used. Was. Also, in order to prevent the output voltage from boosting, very high-speed control is required as a loop speed of the feedback control, and in order to realize high-speed control, components capable of high-speed processing are required. Further, the control becomes complicated, leading to an increase in cost.

When such a conventional DC power supply is applied to an air conditioner, while the air conditioner is operating,
Since the FET 34 continues to operate, a switching loss occurs in the FET 34, which causes a problem that efficiency is reduced. Further, when high-speed switching is performed in the FET 34, noise is generated, and the line filter 29 is enlarged. Such a problem also occurred.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Instead of always causing the switching element to perform a switching operation, the number of times of switching is reduced, thereby reducing the processing speed in control. It is an object of the present invention to provide a DC power supply control device capable of reducing harmonics at a low cost.

[0007]

A DC power supply according to the present invention comprises a rectifier circuit for rectifying a voltage of an AC power supply, a smoothing capacitor for smoothing an output voltage from the rectifier circuit, and The switch means disposed, a reactor disposed on the power supply side of the switch means, a load amount detecting means for detecting a load amount of a load connected in parallel to the smoothing capacitor, and a power supply cycle of the AC power supply. Control means for controlling the opening and closing of the switch means at least twice in a half cycle of the power supply with an opening and closing time according to the load amount.

When the switching means switches between DC bus voltages on the output side of the rectifier circuit,
A diode for preventing backflow from the smoothing capacitor to the switch means.

A rectifier circuit for rectifying the voltage of the AC power supply, a smoothing capacitor for smoothing an output voltage from the rectifier circuit, switch means disposed on the AC power supply side of the smoothing capacitor, and a power supply from the switch means. A reactor arranged on the side, an inverter connected in parallel to the smoothing capacitor, an inverter control unit for driving and controlling the inverter at a desired inverter frequency, and at least a power supply half cycle in synchronization with a power supply cycle of the AC power supply. Twice,
Control means for controlling the opening and closing of the switch means with the opening and closing time according to the inverter frequency.

The control means controls the opening and closing of the switch means at least twice during a period in which no input current flows.

Further, the control means controls to start the second switching before the input current becomes zero by the first switching of the switching means.

A storage means for storing the switching time of the switch means according to the load amount of the load connected in parallel to the smoothing capacitor or the inverter frequency, and the switching means of the switch means according to the load amount of the load or the inverter frequency. Selecting means for selecting a time from a storage means, and at least two times in a power supply half cycle in synchronization with a power supply cycle of the AC power supply.
And control means for controlling the opening and closing of the switch means at an opening and closing time according to the load amount.

Further, in the air conditioner according to the present invention, any one of the DC power supply devices is a DC power supply device for a compressor.

The load detecting means detects a load obtained by the compressor.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 1 of the present invention. In FIG. 1, 1 is an AC power supply, 2 is a full-wave rectification circuit composed of four diodes for full-wave rectification of the voltage of the AC power supply 1, and 3 is one end connected to the positive output side of the full-wave rectification circuit 2. DC reactor 4 for storing energy and smoothing current, 4 is a smoothing capacitor provided between the other end of DC reactor 3 and the negative output side of full-wave rectifier circuit 2 for smoothing a DC bus voltage. Reference numeral 5 denotes a reverse current blocking diode provided between the other end of the DC reactor 3 and the positive side of the smoothing capacitor 4 for preventing current from flowing backward from the smoothing capacitor 4 to the full-wave rectifier 2.

Reference numeral 6 denotes a switch provided between the other end of the DC reactor 3 and the negative output of the full-wave rectifier circuit 2 for switching between DC buses. 7 denotes a load connected in parallel with the smoothing capacitor 4; Reference numeral 8 denotes control means for controlling opening and closing of the switch means 6 at least twice in a half cycle of the power supply based on a power supply synchronizing signal generated from the voltage of the AC power supply 1 for an opening / closing time selected by a selection means described later. Storage means for storing data on the opening and closing time of the switch means 6 set in advance according to the following. 10 is a load amount detecting means for detecting the load amount of the load 7, and 11 is detected by the load amount detecting means 10. This is selection means for appropriately selecting a switch opening / closing time stored in the storage means 9 in advance according to the load amount.

Next, the operation of the DC power supply according to the first embodiment of the present invention will be described. First, the relationship between the input voltage and the input current when the switch means 6 shown in FIG. 1 does not operate at all will be described. When the switch means 6 does not operate at all, when the DC voltage smoothed by the smoothing capacitor 4 is compared with the AC input voltage applied by the AC power supply 1, only when the input voltage is higher than the DC voltage Since the current flows from the AC power supply 1, an input current as shown in FIG. 2 flows, but this current contains a large amount of harmonic components, and this current has a large phase difference from the input voltage. The power factor is also bad.

The switching means 6 shown in FIG.
When the switch is operated only several times during a period in which no input current flows in a half cycle of the power supply,
A current path is formed from the AC power supply 1 to the AC power supply 1 through the full-wave rectifier 2, the DC reactor 3, the switch means 6, the full-wave rectifier 2, and the AC power supply 1. After the switch means 6 has been turned on and closed, even if the switch means 6 is subsequently opened, the input current is not interrupted. This is due to the nature of the DC reactor 3, and since the reactor tends to continue to flow current, the energy stored in the reactor is charged into the smoothing capacitor 4, so that the input current flows. Therefore, the input current continues to flow until the energy stored in the DC reactor 3 is consumed.

FIG. 3 is a waveform diagram showing the relationship between the input current and the input voltage when the switch means 6 is operated only twice during the period in which the input current flows immediately after the zero crossing point in FIG. . Here, Tsw1 is a first delay time until the switch means 6 is closed, and Ton1 is a first delay time until the switch means 6 is closed.
Is the first closing time, Tsw2 is the second delay time until the switch means 6 is closed, and Ton2 is the second closing time when the switch means 6 is closed. When the switch means 6 is closed after passing through the zero cross point, a current path is formed as described above, and a current flows. Even when the switch means 6 is opened, energy is accumulated in the DC reactor 3, and the DC reactor 3 works to supply a current by the energy of the DC reactor 3, so that the switch means 6 is turned off before the current becomes zero. The second switch operation is performed. Then, after the switch means 6 is turned off for the second time, the input voltage becomes higher than the DC voltage and a current flows, and the input current waveform is as shown in FIG. In this way, by operating the switch means 6 to flow the current during the period when the input current does not flow, the phase difference between the voltage and the current is reduced, and the power factor is improved. Further, by controlling the operation timing of the switch means 6, the input current flows not only near the peak but also near the zero cross, so that the harmonics are reduced.

Next, the operation of the DC power supply according to the first embodiment of the present invention shown in FIG. 1 will be described. When power is supplied from the AC power supply 1, the circuit operates, and the load 7 operates. Here, the load 7 performs work by obtaining power by driving a motor, and a driving part for driving the motor is also a part of the load. The motor may be a DC motor or an AC motor, but in the case of a load that obtains power from an AC motor, the DC-AC converter is also a part of the load. For example, a compressor used in an air conditioner is a load not only for the compressor motor but also for the entire compressor and a driving part for driving the compressor motor.

When such a load 7 is operating, the load amount is detected by the load amount detecting means 10. Then, the detected load amount is transmitted to the selection unit 11. Here, the load amount detected by the load amount detecting means 10 is the number of rotations of the motor or the torque generated by the motor, and the load is a compressor used in the air conditioner. In such a case, since the load amount detecting means 10 cannot detect the number of rotations of the motor, the load amount is, for example, an induced voltage from the motor or a flow rate of the refrigerant. Next, selection means 11
In the above, in order to properly open and close the switches of the switch means 6, the open / close time of the switch means 6 according to the load amount detected by the load amount detecting means 10 is selected from the storage means 9,
Notify control means 8. Here, the opening / closing time according to the load amount is stored in the storage unit 9 in advance.
Is operated with an appropriate opening and closing time according to the load.

The control means 8 controls the switching means 6 to open and close during the opening and closing time transmitted from the selecting means 11. Here, the reference of the switching timing of the switch means 6 is based on the power supply synchronization signal input from the AC power supply 1 and the signal generated by the power supply synchronization signal generation means incorporated in the control means 8. That is, the control means 8 controls the switching means 6 to open and close by counting the time for opening and closing the switching means 6 from the reference point when the input AC power supply 1 voltage crosses the zero volt midpoint. Control.

As described above, it is necessary to synchronize with the power supply. However, in the control according to the present invention, an error in power supply synchronization affects the effect of suppressing harmonics. The reason is that the control according to the present invention is configured to control at the switching timing from the true zero-cross point, but if the detected zero-cross point is later than the true zero-cross point, the switching timing Will approach the peak of the fundamental wave. In the present invention, the current is supplied before the peak of the fundamental wave to suppress the third-order component. Therefore, if the delay is later than the true zero-cross point, the amount by which the third-order component is suppressed by the control. It is because it becomes more. Conversely, if the measurement of the switching timing starts earlier than the true zero-cross point, the reduced third-order component is dispersed to the third and higher orders, and the higher-order component increases. This is because it is necessary to reduce the synchronization error. However, speaking of air conditioners,
If the error occurs in the power supply synchronizing signal generating means used by the current product, the error is at a level that does not cause any problem. Is not a problem.

Here, for example, if the AC power supply 1 has a frequency of 50
In the case of Hz, the zero cross point exists twice in one cycle. In other words, the zero-cross point exists once in a half cycle of the AC power supply 1 and the cycle of the power supply is 20 ms.
There will be a zero-cross point once every 0 ms.
Further, if the control means 8 switches the switch means 6 twice, for example, in a half cycle of the power supply, an input current as shown in FIG. 3 flows, the power factor is improved, and harmonics are reduced. Since the above control only operates the switch means 6 several times in 10 ms, there is almost no processing load on the control system caused by controlling the switch means 6. Therefore, the control is simplified, and there is almost no increase in cost caused by executing the control.

In FIG. 3, the switch means 6 is opened and closed only twice in a half cycle of the power supply. However, the switching means 6 is not limited to two times, and the same effect can be obtained if it is opened and closed two to several times. Not even. Conversely, in switching only once every half cycle of the power supply, the DC reactor 3
The inductance value at the point increases, and the outer shape increases. This is because when the input current is caused to flow by the operation of the switch means 6 and the input current becomes zero, not only does the power factor deteriorate, but also the amount of harmonics of higher-order components becomes larger than usual. In addition, it is necessary to store a large amount of energy in the DC reactor 3 in order to prevent the input current from becoming zero with only one switching. Conversely, if the time during which the switch means 6 is closed is prolonged, the steep current becomes too large, and the switch means 6 is closed.
May be damaged, and harmonics cannot be suppressed. Also, when the inductance value increases, the DC reactor 3
The heat generated by the heat increases. For this reason, the switch means 6
Plural switchings are preferable to switching only once.

Next, a method of setting a reactor value and an opening / closing time will be described below. FIG. 4 is a flowchart illustrating a method of setting a reactor value. In step 1, the load amount of the load 7 is set. Here, when a load whose load amount changes, for example, a load such as a compressor of an air conditioner, is used as the load 7, regulation of power supply harmonics is as follows.
Since it is specified that measurement is performed at the maximum rated operation, the load amount at the time of the maximum rating is set. In step 2, the inductance value of the DC reactor 7 is set. In step 3, a combination of the opening and closing times of several switching operations in the switching means 6 is set. Calculating the input current waveform in the circuit using the setting data up to step 3 is the input current calculation in step 4.

Step 5 is an FFT analysis calculation in which the input current waveform calculated in step 4 is subjected to fast Fourier expansion (FFT) to calculate a harmonic component. Step 6 compares the harmonic amount of the input current calculated for each order in step 5 with the regulation value. In step 7, when the comparison result is not less than the regulation value, steps 2 and 3 are performed. Change the setting data in. If the regulation value is satisfied, the setting data in steps 2 and 3 and the analysis data of the input current subjected to FFT are output in step 8. In FIG. 4, the processing is ended in step 8, but in order to obtain a setting for suppressing harmonics, a loop is formed to return to step 2 after step 8, or to return to step 3, Even if the data of the combination of the opening and closing times at regular intervals is created, the input current calculation and the FFT analysis calculation are performed with other setting data, and the other setting data for suppressing the harmonics is obtained. Absent.

Simulation results of the amount of generation of harmonics in the air conditioner having the configuration as shown in FIG. 1 based on the reactor value of the DC reactor 3 and the switching time of the switch means 6 set by the method as shown in FIG. Is shown in FIG. FIG. 5 is a graph comparing the analysis result with the harmonic regulation value. The bar graph shows the analysis result of the amount of generated harmonics, and the line graph shows the harmonic regulation value. The simulation shown in FIG. 5 is based on a model of an air conditioner when the output power is 3300 W. The analysis set values are as follows: the reactor value of the DC reactor 3 is 3 mH, and the first delay time until the switch means 6 is closed. Tsw1 is 1.9 ms, the first closing time Ton1 for closing the switch means 6 is 0.3 ms, and the switch means 6
The second delay time Tsw2 before closing is 0.3 ms,
The second closing time Ton2 for closing the switch means 6 is 0.1 ms.

In the simulation shown in FIG.
FIG. 6 shows the result of the simulation at the time of 2200 W, which was at the time of 00 W. The difference between the set values in FIG. 6 and FIG.
mH. Regarding the opening / closing time of the switch means 6, T
sw1 = 2.4 ms, Ton1 = 0.1 ms, Tsw2
= 0.2 ms, Ton2 = 0.2 ms. From FIG. 6, it is possible to cope with a load such as an air conditioner in which the load amount varies by changing the opening / closing time for operating the switch means 6. Also, in this case, the switch means 6 is operated only twice in a half cycle of the power supply. However, if the number of times the switch means 6 is operated is increased, the reactor value necessary for achieving the same harmonic suppression effect is reduced. However, the number of switching times to be increased is about several times, and if the number of times is excessively increased, not only the above-mentioned problem of the boosting occurs but also the cost increases due to an increase in the processing load of the control system.

When a model of an air conditioner with a 3300 W output is simulated by operating the switch means 6 once, the reactor value of the DC reactor 3 is 4 mH, and the switching time of the switch means 6 is Tsw.
When 1 = 2.3 ms and Ton1 = 0.35 ms, the amount of generation of harmonics satisfying the harmonic regulation value can be suppressed. However, when the number of switches is one, the reactor of the DC reactor 3 is larger than the number of times of two switches. The value increases. FIG. 7 shows a comparison between the simulation result and the regulation value when the number of switches is one. When the reactor value increases, the heat generated in the DC reactor 3 increases, and the outer shape of the DC reactor 3 itself also increases. Therefore, the DC reactor 3 does not reach the boosting region, for example, twice or three times than once. It is clear that a few switches are better. Here, the boost region refers to a switching on time in which a current amount such that the DC bus voltage rises is supplied.

Further, if the load of the load 7 changes with one switching, the regulation value of the harmonic cannot be satisfied only by the switching time of the switch means 6, so that the air conditioner is different from the air conditioner. In order to change the load amount, a plurality of switch times is required. in this way,
Since the opening / closing time of the switch means 6 can be finely changed according to the load amount of the load 7, it is possible to reduce harmonics of the input current while always maintaining a high power factor. Further, since the switching means 6 is opened and closed several times in a half cycle of the power supply, low-frequency switching is realized, switching loss is reduced, high efficiency is achieved, and further, cost reduction can be realized in terms of noise countermeasures. Further, in the high-frequency switching, the necessary feedback is unnecessary because the feedback is the low-frequency switching, and the control is simplified, so that further cost reduction can be realized.

Conversely, in switching only once every half cycle of the power supply, in order to suppress harmonics, the inductance value in the reactor increases, and as the inductance value increases, heat generation in the reactor increases. ,
By performing switching several times in a half cycle of the power supply, it becomes possible to reduce the inductance value of the reactor and reduce heat generation compared to switching only once in a half cycle of the power supply. Further, when the inductance value decreases, the outer shape of the reactor also decreases, so that the reactor can be downsized.

Embodiment 2 FIG. FIG. 8 is a block diagram illustrating a DC power supply device according to Embodiment 2 of the present invention. In the drawing, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. Reference numeral 12 denotes an inverter connected in parallel to the smoothing capacitor 4, reference numeral 13 denotes an inverter control unit that controls the inverter 12, and reference numeral 14 denotes a load that receives an operation mode command and inverter frequency information from the inverter control unit 13 and estimates a load amount applied to the inverter 12. It is a quantity estimating means. The inverter 12 is a driving portion for driving a motor, and the motor is connected to the inverter 12. This motor is, for example, a motor for a compressor used in an air conditioner.

The operation of the DC power supply according to the second embodiment of the present invention shown in FIG. 8 will be described. In an air conditioner using the inverter 12, a required number of rotations and a required rotation force are set depending on an operation state. In addition, since the operating speed of the inverter 12 is determined by the inverter frequency, the set value of the rotating force required for the operation can be known from the operating state and the operating speed. Here, the motor output P
Is determined by the product of the rotational speed n and the rotational force T, and P = k
It is represented by × n × T, where k is a coefficient. Since the motor output P of the motor connected to the inverter 12 is controlled by the inverter control unit 13 to output according to the load amount, the motor output P can be regarded as the load amount. Therefore, if the operating state and inverter frequency are known,
It is possible to estimate the load amount by calculation. Therefore,
The operation mode and the inverter frequency are transmitted to the load estimating means 14 by the inverter control section 13 and the load estimating means 1
By calculating at 4, the load amount can be estimated.

The load estimating means 14 opens and closes the switch means 6 in accordance with the estimated load amount.
The same effect as the invention shown in the first embodiment of the invention can be achieved without operating the load amount detecting means, and operating the air conditioner equipped with the inverter. This means that, in the air conditioner equipped with the inverter, the load amount can be detected without performing the load amount detection by the existing control unit, so that the cost can be reduced as compared with the invention shown in the first embodiment of the invention. It is.

Embodiment 3 FIG. 9 is a block diagram illustrating a DC power supply device according to Embodiment 3 of the present invention. In the drawing, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. 15 is an output current detecting means for detecting an output current flowing through the load 7;
Is the load 7 based on the output current detected by the output current detection means 15.
Load amount calculating means for calculating the load amount.

The operation of the DC power supply according to Embodiment 3 of the present invention shown in FIG. 9 will be described. The output current flowing from the load 7 flows in proportion to the load amount of the load 7. This is because a rotational force T corresponding to the flowing current is generated in the motor. Therefore, the output current is detected, and the load amount is calculated from the detected current value. That is, the load amount is approximated by (output current × DC bus voltage × power factor), and since the DC bus voltage and the power factor during operation are substantially constant, the load amount can be obtained by detecting the output current. . Therefore, the output current detection means 15 detects the output current flowing through the load 7, and the load amount calculation means 16 outputs the load amount of the load 7 calculated from the output current detected by the output current detection means 15 to the selection means 11. Then, Embodiment 1 of the present invention
Similarly to the above, the selecting means 11 selects the opening / closing time according to the load amount from the storage means 9 and notifies the controlling means 8, and the controlling means 8 switches the switching means 6 at an appropriate opening / closing time according to the load 7. .

The third embodiment of the present invention shown in FIG. 9 has a configuration in which an output current detecting means 15 and a load calculating means 16 are provided in place of the load detecting means 10 of the first embodiment. Since the load amount can be detected only by using the load amount calculating means for performing a simple calculation using the output current detecting means, the cost can be reduced as compared with that shown in the first embodiment of the present invention. Further, it is possible to protect circuit elements and the like caused by excess output current.

Embodiment 4 FIG. 10 is a block diagram showing a DC power supply device according to Embodiment 4 of the present invention. In the drawing, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. 17 is an output voltage detecting means for detecting an output voltage flowing to the load 7;
Is the load 7 based on the output voltage detected by the output voltage detecting means 17.
Load amount calculating means for calculating the load amount.

The operation of the DC power supply according to the fourth embodiment of the present invention shown in FIG. 10 will be described. In the fourth embodiment, as in the first embodiment, the switch means 6 is operated only several times in a half cycle of the power supply. However, this operation is performed so that the switch timing of the switch means 6 does not operate in the boosting region. Is set, the DC bus voltage causes a voltage drop due to the resistance existing in the DC reactor 3. In this case, as the load amount of the load 7 increases, the voltage drop increases, and conversely, when there is no load amount of the load 7, no voltage drop occurs.

Therefore, when the DC bus voltage when there is no load on the load 7 is used as a reference, the load can be estimated from the voltage drop from the reference voltage. For example, if the reference voltage is 282 V and the load is 80% of the maximum rating, the output voltage drops by about 20 V, so the voltage value detected by the output voltage detecting means 17 is 262 V. it is conceivable that. In other words, when the detected voltage value of the output voltage means 16 is 262 V, the load amount can be estimated to be about 80% of the maximum rating. Therefore, the output voltage detecting means 17 detects the output voltage applied to the load 7, and the load amount calculating means 18 outputs the load amount of the load 7 calculated from the output voltage detected by the output voltage detecting means 17 to the selecting means 11. I do. Then, as in the first embodiment of the present invention, the selection means 11 selects the opening / closing time corresponding to the load amount from the storage means 9 and notifies the control means 8, and the control means 8 sends the switch means 6 to the load 7. The switch is operated at the appropriate opening / closing time.

The fourth embodiment of the present invention shown in FIG. 10 has a configuration in which an output voltage detecting means 16 and a load calculating means 17 are provided instead of the load detecting means 10 of the first embodiment. Since the load amount can be detected only by using the load amount calculating means for performing a simple calculation using the output voltage detecting means, the cost can be lower than that shown in the first embodiment of the invention. Further, the existing overvoltage detecting means is designed to handle only the output voltage excess. However, the output voltage detecting means 16 and the load amount calculating means 17 can protect overcurrent, malfunction and the like due to low voltage. .

Embodiment 5 FIG. FIG. 11 is a block diagram illustrating a DC power supply device according to Embodiment 5 of the present invention. In the drawing, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. 19 is a temperature rise detecting means for detecting a temperature rise of the switch means 6;
Numeral 0 denotes a load calculating means for calculating the load of the load 7 from the temperature rise value detected by the temperature rise detecting means 19.

The operation of the DC power supply according to the fifth embodiment of the present invention shown in FIG. 10 will be described. First, before the switch means 6 starts operating, the ambient temperature is detected by the temperature rise detection means 19. Thereafter, when the switching means 6 starts operating, the temperature rise of the switching means 6 is detected. The reason why the temperature of the switch means 6 rises is because of switching loss in the switch means 6. Assuming that the switching loss is Pc, the current flowing through the switching element is I, and the on-resistance of the switching element is Ron, the switching loss Pc can be expressed as Pc = I ² × Ron. Also, the case temperature Tc of the switching element and the ambient temperature Tn
Is used, the temperature rise value Tα can be approximated by Tα = Tc−Tn. Here, the relationship between the temperature rise value Tα and the switching loss Pc is as follows.
c can be approximated by Pc = k × Tα (k is a coefficient).

Therefore, Pc = k × Tα = k × (Tc−T
n) = I ² × Ron, so that I can be obtained if Tc, Tn, Ron, and k are known. Where Ron, k
Is a value determined by the switching element used, so I is the temperature rise value T obtained by detecting Tc and Tn.
It can be obtained from α. The ambient temperature Tn is almost the same as the temperature of the sufficiently cooled switching element before switching starts. I is a current value when the switch means is turned on, and is a value that varies depending on the load amount. If the current value flowing through the switch means is known, the load amount can be estimated from the current value as described above. . From this, the current value flowing through the switch means 6 is obtained from the temperature rise value of the switch means 6, the load amount is estimated from the current value, and the control means 8 controls the switch means 6 to operate.

Therefore, the temperature rise detecting means 19 detects the temperature rise of the switch means 6, and the load calculating means 20 first calculates the current value from the temperature rise value detected by the temperature rise detecting means 19, and then calculates the current value. The load amount of the load 7 is calculated from the current value, and the calculated load amount of the load 7 is output to the selection unit 11. Then, as in the first embodiment of the present invention, the selection means 11 selects the opening / closing time corresponding to the load amount from the storage means 9 and notifies the control means 8, and the control means 8 sends the switch means 6 to the load 7. The switch is operated at the appropriate opening / closing time.

The fifth embodiment of the present invention shown in FIG. 11 employs a configuration in which a temperature rise detecting unit 19 and a load calculating unit 20 are provided instead of the load detecting unit 10 of the first embodiment. The same operation as described in the first embodiment can be performed. In addition, temperature rise detecting means 1
The provision of 9 also makes it possible to protect the temperature of the switch means 6 and to prevent deterioration and breakage of the switch element used for the switch means 6.

Embodiment 6 FIG. FIG. 12 is a block diagram illustrating a DC power supply device according to Embodiment 6 of the present invention. In the drawing, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. Reference numeral 21 denotes the number of times the switch means 6 is opened and closed in a half cycle of the power supply.
The opening / closing time of the switch means 6 not stored is calculated from the load amount detected by the load amount detecting means 10 and the opening / closing time of the switch means 6 stored in the storage means 9 for the remaining times. It is a calculating means.

The operation of the DC power supply according to the fifth embodiment of the present invention shown in FIG. 10 will be described. The storage unit 9 stores data of a delay time Tsw1 from the zero crossing point of the AC power supply 1 to the closing of the switch unit 6 and data of a closing time Ton1 in which the switch unit 6 is closed according to the load amount. The load amount detection means 10 detects the load amount, the selection means 11 appropriately selects Tsw1 and Ton1 from the storage means 9 in accordance with the detected load amount, and selects the Tsw1 and Ton1 from the control means 8 and the calculation means. Tell 21. Regarding the first opening / closing of the switch means 6 in the half cycle of the power supply, the control means 8 determines whether Tsw1 and Tsw
The switch means 6 is opened and closed by on1. For the opening and closing of the switch means 6 after the first time in the half cycle of the power supply, the open / close time calculated by the calculation means 21 is output to the control means 8 via the selection means 11, and the control means 8 uses the calculated open / close time. The switch means 6 is opened and closed.

Here, a method of calculating the remaining opening / closing time by the calculating means 21 will be described. For example, in the case of a control device for a DC power supply of an air conditioner for domestic use, the calculation is performed as follows. If the load amount is αkW, the inductance value of the reactor is L [mH], the second delay time until the switch means 6 is closed is Tsw2, and the time when the switch means 6 is closed for the second time is Ton2, Tsw2 = (L -T
sw1) / α, Ton2 = Ton1 / α, and the opening / closing time of the second switch means 6 is obtained by the above calculation method. When opening and closing three or more times, Tsw3 = Tsw2 / α, Ton3 = Tsw3
It is obtained by two equations of on2 / α. The above two equations are created based on experiences such as experiments and simulations.

As described above, since the opening and closing times of the second and subsequent times can be sequentially obtained based on the previous one, even if the number of times of opening and closing by the switch means 6 is increased, the calculating means 21 can be used. Without increasing the storage capacity of the storage means 9,
It can be opened and closed several times in a half cycle of the power supply. It is assumed that the calculating means 21 itself stores the opening and closing times obtained one after another after the second time. Further, since the storage amount required according to the number of operations of the switch unit 6 in the storage unit 9 can be reduced to one storage amount, as the number of times of opening and closing increases, the degree of decrease in the total storage amount increases. Thus, the size of the storage element can be reduced. In addition, since the total storage amount is reduced, it is possible to store a longer opening / closing time according to the load amount when elements having the same storage amount are used,
High power factor and harmonic suppression control can be finely performed.

Embodiment 7 FIG. FIG. 13 is a block diagram showing a DC power supply according to Embodiment 7 of the present invention. In the drawing, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. Reference numeral 22 denotes a power supply unit connected in parallel to the smoothing capacitor 4, and 23 denotes a power supply control unit that controls the power supply unit 22. The power supply control unit stops the control unit itself based on a stop signal generated by detecting an abnormality when an abnormality occurs. It has a function part 23a. Further, the control means 8 of the present embodiment detects a malfunction at the time of an abnormality, and stops the control unit itself based on a stop signal generated by the abnormality.
Having. The stop function unit 8a of the control unit 8 and the stop function unit 23a of the power supply control unit 23 are connected by a signal line 24, and the power supply control unit 23 is connected to the stop function unit 23.
a stops when it receives the stop signal from the stop function unit 8a of the control unit 8, and the control unit 8 stops the stop function unit 8a when it receives the stop signal from the stop function unit 23a of the power supply control unit 23. It has a configuration that works together. A power supply device is configured by the power supply unit 22 and the power supply control unit 23, and examples of the power supply device include an inverter and the like.

The operation of the DC power supply according to the seventh embodiment of the present invention shown in FIG. 13 will be described. In FIG. 13, when the switch unit 6 is operating while the power supply unit 22 is stopped, a steep pulse-like current flows through the switch unit 6, and energy is stored in the DC reactor 3. However, since the power supply unit 22 is stopped, the energy of the smoothing capacitor 4 is not transmitted to the power supply unit 22. For this reason, the smoothing capacitor 4 cannot discharge, the energy remains stored, and the smoothing capacitor 4 does not shift to the discharging state. The energy stored in the DC reactor 3 is not discharged from the DC reactor 3 but is merely stored since the smoothing capacitor 4 in the receiver of the energy of the DC reactor 3 stores the energy. Therefore, the voltage component in DC reactor 3 is added to the DC bus voltage, and the DC bus voltage rises. The boosting of the DC bus voltage causes the deterioration of the smoothing capacitor 4, and the inflow of a steep pulse-like current into the switch means 6 leads to failure / damage of the switch means 6.

If the switch means 6 is not operated while the power supply means 22 is operating, the operation is performed with the power factor lowered. Since output power is approximated by power factor × output voltage × output current, the output current increases when the same power is output in an operation in a state where the power factor is reduced. This is because the DC bus voltage is
Because it is determined by the capacity of the battery and becomes almost constant. Therefore, a current larger than the expected current value flows through the power supply unit 22. The increase in the output current caused by the decrease in the power factor causes failure of not only the power supply means 22 but also the full-wave rectifier circuit 2, the DC reactor 3, the backflow prevention diode 5, the smoothing capacitor 4, and the like in the current path. Become. Therefore, in the DC power supply control device including the switch means 6 and the like and the power supply device including the power supply means 22 and the power supply control unit 23, operating only one of them causes a failure. Embodiment 7 of the present invention has been made to solve such a problem.

For example, in the power supply device, when the stop function unit 23a of the power supply control unit 23 detects an abnormality and stops the control unit itself based on the stop signal, the control unit 8 of the DC power supply control unit The stop function unit 8a receives the stop signal from the stop function unit 23a of the power supply control unit 23 and stops the control unit itself. When the stop function unit 8a of the control unit 8 of the DC power supply control device detects an abnormality and stops the control unit itself based on the stop signal, the stop function unit 23a of the power supply control unit 23 of the power supply device is activated. Control means 8
The control unit itself is stopped in response to a stop signal from the stop function unit 8a.

As described above, while the power supply device and the DC power control device operate independently, the DC power control device is always stopped when the power supply device is stopped, and the power supply device is always stopped when the DC power control device is stopped. Is stopped to prevent failure of components constituting the circuit. Also,
Since the operation of only one of the power supply device and the DC power supply control device is eliminated, a highly reliable DC power supply device can be provided. Further, in the above embodiment, the power supply means 22 is connected in parallel to the smoothing capacitor 4, and the power supply means 22 is applied to a DC power supply device controlled by the power supply control unit 23. In the DC power supply device according to the second embodiment, the inverter control unit 13
Has a stop function unit for stopping the control unit itself on the basis of a stop signal generated upon detection of an abnormality in the event of an abnormality.
Has a stop function unit that stops the control unit itself based on a stop signal generated by detecting an abnormality in the event of an abnormality, and the stop function unit of the inverter control unit 13 and the stop function unit of the control unit 8 are connected by a signal line. It is needless to say that the same operation and effect as in the seventh embodiment of the present invention can be obtained.

Embodiment 8 FIG. FIG. 14 is a block diagram illustrating a DC power supply device according to Embodiment 8 of the present invention. In the figure, the same components as those of the seventh embodiment of the present invention are denoted by the same reference numerals, and the description of the duplicated components will be omitted. 25 detects the current flowing from the smoothing capacitor 4 and the switch means 6 to the DC bus, and when the current exceeds a certain set value, the power supply control unit 20 stops the operation of the power supply means. And an overcurrent detecting means for issuing a command to the control means 8 to stop the switch means 6 when the detected current exceeds a certain set value set close to the peak value.

The operation of the DC power supply according to the eighth embodiment of the present invention shown in FIG. 14 will be described. In FIG. 14, when a current larger than a normal current flows on the bus due to a failure, the switch unit 6 of the DC power supply control unit and the power supply unit 19 of the power supply unit operate to protect the product. Need to stop. Either the switching means 6 or the power supply means 22 is provided with an overcurrent detection means, or any of the switching means 6 and the power supply means 22 is provided with an overcurrent detection means. It is necessary to adopt a configuration in which the current detection means is not provided. In the former case, two overcurrent detecting means are required, and in the latter case, it is not clear which is the cause of the overcurrent occurrence.

In the eighth embodiment of the present invention, protection of the switching means 6 and the power supply means 19 from overcurrent is realized by one overcurrent detecting means, and the overcurrent generating source is specified. Things. In FIG. 14, when an overcurrent flows due to a failure of the switch means 6, a steep current flows through the overcurrent detection means 24 from the switch means 6 to the negative side of the full-wave rectifier circuit 2. Conversely, when the load 7 to which power is supplied from the power supply means 22 is overloaded, the load 7 consumes a current larger than the current flowing in the normal state, and the current flowing through the entire circuit increases. I do. Further, even when the power supply means 22 causes a short-circuit fault, the peak current flows, but the direction of the flow is opposite to the peak current caused by the inconvenience of the switch means 6 of the DC power supply control device. The current flows from the supply means 22 to the positive side of the full-wave rectifier circuit 2 through the smoothing capacitor 4 via the negative electrode side of the full-wave rectifier circuit 2, and flows back so as to be regenerated to the power supply means 19 because the backflow is prevented by the diode 5. .

As described above, it is possible to detect from the flow of the bus current that there is an overcurrent flowing due to a malfunction of the switch means 6 or the power supply means 22, and it is possible to specify the device that caused the overcurrent. In addition, since overcurrent due to overload can be recognized, failure of the DC power supply and the power supply device can be prevented, and it is possible to specify that the DC power supply control device and the power supply device are not failures.

Here, the operation of the control means 8 and the power supply control unit 20 after detecting an overcurrent will be described. First, when a steep current near the peak value flows, the overcurrent detection means 25 controls the control means 8 to stop the switch means 6 when the steep current is larger than the second set reference value. A control means stop signal is sent to the control means 8 and the control means 8 receiving the control means stop signal stops the switch means 6. This means that if the DC power supply control unit has failed,
This is because all components after the DC power supply may be damaged. If the direction in which the steep overcurrent flows is from the negative side of the full-wave rectifier 2 to the negative side of the smoothing capacitor 4, it is a failure of the power supply device. If it flows to the negative electrode side, it is determined that the DC power supply control device has failed. Then, since it is not preferable to operate in a failure state, the control unit 8 issues a stop command signal to the power supply control unit 23 so as to stop the power supply unit 22 after a predetermined time has elapsed, and outputs the stop command signal. The received power supply control unit 23 stops the power supply unit 22, stops the operation of the power supply device, and prevents a failure of other components.

When the overcurrent detecting means 22 is not a steep current but the overcurrent is caused by an overload and the current increases to some extent, the overcurrent detecting means 25 determines that the increased current is the first current. The control unit 23 sends a control unit stop signal to the power supply control unit 23 so as to stop the power supply unit 22 when the power supply control unit 23 is larger than the set reference value. Stop. By stopping the operation of the power supply unit 22, damage to the load to which power is supplied from the electrode supply unit 22 is prevented, and damage to the power supply device is also prevented. Then, the power supply control section 23 issues a stop command signal to the control means 8 so as to stop the switch means 6 after a lapse of a predetermined time, and the control means 8 which has received the stop command signal stops the switch means 6 and outputs the other components. It is intended to prevent the failure. As described above, both the DC power supply control device and the power supply device are stopped, and after a certain period of time, the operation is started again, and if no overcurrent occurs, it is a temporary overload state, or the input fluctuates. , There is no problem even if the operation is restarted.

Furthermore, as described in the above embodiment, the operation of only one of them causes a failure or deterioration. Therefore, when a steep overcurrent or a rise in overcurrent is detected, there is no problem even if the operations of the DC power supply device and the power supply device are stopped at the same time. If both are stopped at the same time after detecting an overcurrent, it is not clear which is the cause, and it may be a temporary overcurrent stop due to input / output fluctuations, or an overcurrent stop due to a failure. There is a risk that it may not be possible to determine whether it is something. Therefore, stop only one side,
As soon as the cause of the occurrence of the overcurrent is specified, the other device is stopped, thereby preventing the device from being deteriorated or damaged due to the overcurrent.

By detecting the direction of the peak current with the overcurrent detecting means 25, it is possible to identify whether the DC power supply control device or the power supply device is the source of the overcurrent, and to detect the rise of the current. As a result, it is possible to protect the load in the overload state, and also to protect the two devices and the load with one overcurrent detection unit 24, thereby contributing to downsizing of the circuit configuration and cost reduction. Things. In the above embodiment, the overcurrent detection means 25 detects the current flowing from the smoothing capacitor 4 and the switch means 6 to the DC bus, and when the current exceeds a certain set first reference value, the power supply The controller 23 is instructed to stop the operation of the power supply means 22. The average value of the current detected by incorporating an integrator or a constant time constant circuit is equal to a first set reference value. May be issued to the power supply control unit 23 to stop the operation of the power supply unit 22. In this case, a malfunction due to a transient current rise can be prevented.

Further, in the above embodiment, the power supply means 22 is connected in parallel to the smoothing capacitor 4, and the power supply means 22 is applied to a DC power supply device controlled by the power supply control unit 23. Also has a stop function unit for stopping the control unit itself based on a stop signal generated by the inverter control unit 13 detecting an abnormality when an abnormality occurs, and A stop function unit for stopping the control unit itself based on a stop signal generated by detecting an abnormality at the time, and a stop function unit of the inverter control unit 13 and a stop function unit of the control unit 8 are connected by a signal line; A current flowing from the smoothing capacitor 4 and the switch means 6 to the DC bus is detected, and when the current exceeds a certain set value, the power supply control unit 20
Is issued to stop the operation of the power supply means, and when the detected current exceeds a certain set value set close to the peak value, a command is issued to the control means 8 to stop the switch means 6. It goes without saying that the provision of the overcurrent detecting means has the same operation and effect as the eighth embodiment of the present invention.

[0066]

According to the present invention, there is an effect that the power factor of the input current can be improved and harmonics can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a DC power supply device according to a first embodiment of the present invention.

FIG. 2 is an operation input current waveform diagram when the switch means of the DC power supply device is not operating.

FIG. 3 is an operation input current waveform diagram when a switch means of the DC power supply device is operating.

FIG. 4 is a flowchart showing a method for setting a reactor value and an opening / closing time.

FIG. 5 is a graph showing a comparison between a harmonic generation amount and a regulation value when an operation simulation is performed with the configuration of the DC power supply device.

FIG. 6 is a graph showing a comparison between a harmonic generation amount and a regulation value when an operation simulation of different outputs is performed in the configuration of the DC power supply device.

FIG. 7 is a graph showing a comparison between a harmonic generation amount and a regulation value when a simulation is performed by operating the switch means once in a power supply half cycle in the configuration of the DC power supply device.

FIG. 8 is a block diagram illustrating a configuration of a DC power supply device according to a second embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 3 of the present invention.

FIG. 10 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 4 of the present invention.

FIG. 11 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 5 of the present invention.

FIG. 12 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 6 of the present invention.

FIG. 13 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 7 of the present invention.

FIG. 14 is a block diagram illustrating a configuration of a DC power supply device according to Embodiment 8 of the present invention.

FIG. 15 is a block diagram showing a configuration of a conventional DC power supply device.

[Explanation of symbols]

1 AC power supply, 2 full-wave rectifier, 3 DC reactor,
5 backflow preventing diode, 6 switch means, 7 load, 8 control means, 9 storage means, 10 load amount detection means, 11 selection means.

Claims (8)

[Claims] 1. A rectifier circuit for rectifying a voltage of an AC power supply, a smoothing capacitor for smoothing an output voltage from the rectifier circuit, a switch disposed closer to the AC power supply than the smoothing capacitor, and a power supply from the switch. And a load detecting means for detecting a load of a load connected in parallel to the smoothing capacitor; and a load at least twice in a power supply half cycle in synchronization with a power supply cycle of the AC power supply. And a control means for controlling the opening and closing of the switch means at a corresponding opening and closing time. 2. The switching device according to claim 1, further comprising: a diode for preventing backflow from the smoothing capacitor to the switching device when the switching device switches between DC bus voltages on the output side of the rectifier circuit. A DC power supply as described. 3. A rectifier circuit for rectifying a voltage of an AC power supply, a smoothing capacitor for smoothing an output voltage from the rectifier circuit, a switch disposed closer to the AC power supply than the smoothing capacitor, and a power supply from the switch. An inverter connected in parallel with the smoothing capacitor; an inverter control unit for driving and controlling the inverter at a desired inverter frequency; and at least a power supply half cycle in synchronization with a power supply cycle of the AC power supply. A DC power supply device comprising: control means for controlling the opening and closing of the switch means twice in an opening and closing time according to the inverter frequency. 4. The DC power supply device according to claim 1, wherein said control means controls opening and closing of said switch means at least twice during a period when no input current flows. 5. The control device according to claim 1, wherein the control device controls the second switching operation before the input current becomes zero by the first switching operation. DC power supply. 6. A storage means for storing an open / close time of a switch means according to a load amount of a load connected in parallel to the smoothing capacitor or an inverter frequency, and opening and closing of the switch means according to a load amount of the load or an inverter frequency. Selection means for selecting a time from a storage means; and control means for controlling opening and closing of the switch means at least twice in a power supply half cycle in synchronization with a power supply cycle of the AC power supply, in accordance with a load amount. The direct-current power supply according to any one of claims 1 to 5, characterized in that: 7. An air conditioner, wherein the DC power supply device according to any one of claims 1 to 6 is used as a DC power supply device for a compressor. 8. The air conditioner according to claim 7, wherein said load amount detecting means detects a load amount obtained by a compressor.