JP2001314084A - Power supply apparatus, motor drive apparatus and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply apparatus which can suppress an over boosted voltage and a hunting of a DC voltage outputted with a light load and to provide a motor drive apparatus and an air conditioner using the power supply apparatus. SOLUTION: A switching operation control means 11 improves a power factor and, when a switching operation of a switching device 4 is controlled so as to reach a DC voltage outputted to a load 7 to a predetermined target DC voltage, restricts a lower limit value of a target current effective value of a current inputted from an AC power supply 1, discontinues the switching operation if the DC voltage exceeds a 1st level higher than the target voltage, and, if the DC voltage is higher than the target DC voltage and lower than a 2nd level lower than the 1st level, restores the switching. With this constitution, the DC voltage in a light load state is restricted between the 1st level and the 2nd level, so that an excessive voltage rise and hunting of the DC voltage can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying a stable DC voltage to industrial and consumer electronic devices, and a motor driving device and an air conditioner using the same.

[0002]

2. Description of the Related Art In recent years, with the spread of home appliances and industrial equipment, harmonic currents have flowed into a power system, and problems such as heat generation and malfunction of various equipment have come to occur. In response to these problems, various devices require harmonic countermeasures, and accordingly the power supply in the device uses the energy storage effect of the switching operation of the reactor and switching element to improve the power factor. An AC / DC converter circuit for boosting an output voltage has been used.

FIG. 18 is a block diagram showing the configuration of the conventional power supply device. In FIG. 18, 1 is an AC power source, 2
Is a rectifier circuit, 3 is a reactor, 4 is a switching element, 5
Is a diode, 6 is a smoothing capacitor, 7 is a load, 8 is current detection means, 9 is input voltage detection means, 10 is DC voltage detection means, and 11 is switching operation control means. Here, the rectifier circuit 2, the reactor 3, the switching element 4, the diode 5, and the smoothing capacitor 6 constitute an AC / DC conversion circuit, and the switching operation control means 11 controls the operation of the switching element 4.

The operation of the above configuration will be described.
FIG. 19 is a flowchart showing the control operation of the above conventional example. The DC voltage obtained by the DC voltage detecting means 10 includes:
Due to the characteristics of the AC / DC converter, a ripple component having a frequency twice as high as the AC power supply frequency as shown in FIG. 2B is generated. If the control operation described below is performed while the ripple component is included in the DC voltage, the ripple component is redundant in the target current effective value, and finally the input current waveform is distorted. In order to eliminate the ripple component, a DC voltage smoothed by the low-pass filter 12 having a low cutoff frequency is obtained. On the other hand, the target voltage calculation means 13
A predetermined target DC voltage of the DC voltage is calculated and set. The voltage comparing means 14 compares the smoothed DC voltage with the target DC voltage to obtain a voltage difference value.

The target current effective value calculation means 15 obtains a target current effective value by multiplying the voltage difference value and the voltage gain. The target current instantaneous value calculation means 16 normalizes the voltage of the AC power supply 1 obtained by the input voltage detection means 9 and multiplies the value by the target current effective value obtained by the target current effective value calculation means 15. Obtain the target current instantaneous value. The current comparison means 17 compares the instantaneous target current value with the input current detected by the current detection means 8 to obtain a current difference value. The PWM duty calculator 18 multiplies the current difference value by a current gain to calculate a pulse width for turning on the switching element 4. The PWM output determination unit 19 determines whether to perform a switching operation with the pulse width obtained by the PWM duty calculation unit 18 based on a control operation command or the like. By performing the above switching operation normally, control is performed so that the AC power supply voltage and the input current have the same phase, that is, the power factor is 1, and the DC voltage is a predetermined target DC voltage.

In this conventional power supply device, when the load 7 connected to the output is a light load smaller than the controllable power consumption, the DC voltage sharply rises above the target DC voltage by performing the above switching operation. Resulting in. For example, when a motor is connected to the output, if the motor is stopped or rotating at a low speed, the DC voltage is in an excessively boosted state. This is because the time constant of the low-pass filter 12 having a low cutoff frequency is large, and the subsequent control and switching operations are performed without recognizing a sharp rise in the DC voltage under light load.

According to the means described in Japanese Patent Application Laid-Open No. Hei 7-115788, when the load is a motor, in order to prevent the DC voltage from being excessively boosted at the time of light load, the power consumption of the motor is stopped or the power consumption of the motor is reduced. When it is small, the switching operation is completely stopped to prevent over-boosting. Also,
In the means described in Japanese Patent Application Laid-Open No. H10-127083, the switching operation is stopped when the difference between the DC voltage and the target DC voltage becomes equal to or more than a predetermined threshold value to prevent an excessive boost.

[0008]

In such a conventional power supply device, the means for completely stopping the switching operation at a light load is, for example, when a commercial power supply is used.
When the switching operation is stopped, the AC / DC conversion circuit becomes a capacitor input circuit, and the output DC voltage is about 140 V. This value is not arbitrarily determined depending on the AC power supply voltage. Further, if the predetermined target DC voltage of the DC voltage is 170 V, the fluctuation range of the DC voltage accompanying the start and stop of the switching operation is about 30 V,
If the target DC voltage is 200 V, the fluctuation range of the DC voltage is about 60 V. The allowable range of the DC voltage variation varies depending on the system in which the power supply device is used. However, as described above, a system that attempts to raise the AC power supply voltage higher has a disadvantage in that the DC voltage variation width increases, and thus is disadvantageous.

On the other hand, the means for stopping the switching operation when the difference between the DC voltage and the target DC voltage becomes equal to or more than a predetermined threshold value is to set the DC voltage at light load to be near an arbitrary target DC voltage. However, it has the following problems.

That is, as shown in FIG.
In the switching operation at the time of light load, even if the DC voltage is excessively boosted, the DC voltage only increases to a voltage obtained by adding a predetermined threshold value to the target DC voltage of the DC voltage. However, due to the slow time constant of the low-pass filter 12 having a low cutoff frequency shown in FIG. 19, even when the DC voltage decreases below the target DC voltage, the filter operation value of the low-pass filter 12 is smaller than the target DC voltage of the DC voltage. Therefore, the switching operation is not restarted for a while. As a result, the fluctuation range of the DC voltage becomes equal to or larger than the threshold.

The present invention has been made to solve the above problems, and a power supply device capable of minimizing the fluctuation range of a DC voltage under a light load without increasing the scale of the device and supplying power more stably. It is an object of the present invention to provide a motor drive device and an air conditioner that have been used.

[0012]

According to a first aspect of the present invention, there is provided an AC / DC conversion circuit that includes at least a switching element, a reactor, and a diode, and obtains a DC voltage from an AC power supply by a switching operation of the switching element. Switching operation control means for controlling an operation of a switching element, wherein the switching operation control means includes a target current effective of an input current flowing through the AC / DC conversion circuit so as to obtain the predetermined DC voltage while improving a power factor. When the switching operation is controlled by setting the value and the target current effective value, the lower limit value is regulated on the target current effective value, and the output DC voltage is higher than or equal to a first level higher than a predetermined target DC voltage. If the switching operation is stopped, the DC voltage becomes higher than the predetermined target DC voltage. If below a second level which is less than the first level is a power supply device for controlling to restart the switching operation.

According to the present invention, the fluctuation of the DC voltage at the time of light load can be suppressed between the first level and the second level.

According to a second aspect of the present invention, there is provided an AC / DC conversion circuit including at least a switching element, a reactor, and a diode, for obtaining a DC voltage from an AC power supply by a switching operation of the switching element, and controlling an operation of the switching element. Switching operation control means, wherein the switching operation control means includes a target current effective value and a target current instantaneous value of an input current flowing through the AC / DC conversion circuit so as to obtain the predetermined DC voltage while improving a power factor. When controlling the switching operation by setting
The lower limit value is regulated on the target current effective value, and when the output DC voltage becomes equal to or higher than a first level higher than a predetermined target DC voltage, the switching operation is stopped, and the DC voltage becomes lower than the predetermined target DC voltage. A power supply device that controls the switching operation to restart at a second level that is higher than the DC voltage and lower than the first level and equal to or lower than the second level and at a zero-cross timing of the AC power supply voltage of the AC power supply.

According to the present invention, the fluctuation of the DC voltage at the time of light load is suppressed between the first level and the second level, and an excessive input current does not flow when the switching operation is restarted. be able to.

According to a third aspect of the present invention, the first level and the second level are controlled by changing the first level and the second level in accordance with a load amount or an input current or a target current effective value reflecting the load amount. A power supply device according to any one of claims 1 to 2.

According to the present invention, while suppressing the fluctuation of the DC voltage at the time of light load between the first level and the second level,
It is possible to prevent the switching operation from stopping even when the load increases.

According to a sixth aspect of the present invention, there is provided a power supply apparatus according to any one of the first to fifth aspects, wherein the first level and the second level are changed and controlled within a half cycle of an AC power supply. is there.

According to the present invention, the fluctuation of the DC voltage under a light load is suppressed between the first level and the second level while preventing the switching operation from being stopped due to the influence of the ripple component in the DC voltage. Can be.

The present invention according to claim 7 is the power supply device according to any one of claims 1 to 6, wherein either a microcomputer or a digital signal processor is used for the switching operation control means.

According to the present invention, it is possible to utilize the excellent arithmetic functions of a microcomputer or a digital signal processor and to easily set an arbitrary constant used for control.

According to an eighth aspect of the present invention, there is provided a motor driving device provided with an inverter for driving an electric motor at the output of the power supply device according to the first to seventh aspects of the present invention.

According to the present invention, it is possible to realize a motor drive device that operates stably with small fluctuations in the AC voltage output from the inverter.

According to a ninth aspect of the present invention, there is provided an air conditioner using the motor driving device according to the eighth aspect of the present invention.

According to the present invention, an air conditioner that operates stably can be realized.

[0026]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of an AC / DC conversion circuit including at least a switching element, a reactor, and a diode for obtaining a DC voltage from an AC power supply by a switching operation of the switching element; Current detection means for detecting an input current flowing through a conversion circuit, input voltage detection means for detecting an AC power supply voltage of the AC power supply, DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit, From the input current, the AC power supply voltage, and the DC voltage, a target current effective value and a target current instantaneous value of the input current are calculated to improve a power factor, and the DC voltage is set to a predetermined target DC voltage. Switching operation control means for controlling the operation of the switching element so that the switching operation control means, The lower limit of the target current effective value is regulated, and the switching operation is stopped when the DC voltage is equal to or higher than a first level higher than the predetermined target DC voltage, and the DC voltage is higher than the predetermined target DC voltage. A power supply device that controls so as to restart the switching operation when the voltage falls below a second level that is significantly lower than the first level.

In the present invention, the configurations of the AC / DC converter, the current detecting means, the input voltage detecting means, and the DC voltage detecting means may be the same as those of the conventional example. On the other hand, in addition to the configuration and operation of the conventional example, the switching operation control means regulates the lower limit of the target current effective value and stops the switching operation when the DC voltage becomes equal to or higher than a first level higher than the target DC voltage. When the DC voltage falls below a second level that is higher than the target DC voltage and lower than the first level, the switching operation is restarted. Here, the first level is a level that is set as an upper limit of the output DC voltage, and the second level is a level that is set as a lower limit below the first level, and can be arbitrarily set. . Further, the lower limit value of the target current effective value is to provide a lower limit value to the target current effective value calculated by the target current effective value calculation means. It works so that it does not become smaller than the lower limit.

Thus, the switching operation control means increases the DC voltage by setting the target effective current value to the lower limit larger than the value suitable for the light load when the load is light, and the switching operation is performed correspondingly. By stopping and restarting, the DC voltage is suppressed between the first level and the second level. When the load increases, the switching operation does not stop and restart, and the DC voltage converges on the target DC voltage.

According to a second aspect of the present invention, there is provided an AC / DC conversion circuit that includes at least a switching element, a reactor, and a diode, and obtains a DC voltage from an AC power supply by a switching operation of the switching element. Current detection means for detecting an input current; input voltage detection means for detecting an AC power supply voltage of the AC power supply; DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit; From the AC power supply voltage and the DC voltage, to improve the power factor while calculating the target current effective value and the target current instantaneous value of the input current, and so that the DC voltage becomes a predetermined target DC voltage. Switching operation control means for controlling an operation of a switching element, wherein the switching operation control means While regulating the flow effective value to the lower limit, the switching operation is stopped when the DC voltage is equal to or higher than a first level higher than the predetermined target DC voltage, and the DC voltage is higher than the predetermined target DC voltage. A power supply device that controls the switching operation to be restarted at a second level that is less than a first level and equal to or lower than a second level and at a zero-cross timing of the AC power supply voltage.

In the present invention, the switching operation control means suppresses the fluctuation of the DC voltage at the time of a light load between the first level and the second level as well as the AC according to the first aspect of the present invention. By restarting the switching operation at the zero cross timing of the power supply voltage, it is possible to prevent an excessive rush current from flowing to the AC / DC converter circuit when the switching operation is restarted.

According to a third aspect of the present invention, the switching operation control means performs control by changing the first level and the second level in accordance with the amount of load connected to the output of the AC / DC converter. A power supply device according to any one of claims 1 and 2.

In the present invention, the switching operation control means changes the first level and the second level in accordance with the magnitude of the load, and the first level and the second level are changed. The control of the present invention according to claim 2 is performed. That is, when the ripple component in the DC voltage increases with an increase in the load, the DC voltage with the ripple component is more likely to exceed the first level than when the ripple component is not included. , The switching operation stops. As a countermeasure, the first level is increased according to the size of the load so that a margin between the DC voltage and the first level can be secured.
In addition, the second level is increased to maintain the fluctuation range. This prevents the switching operation from stopping even if the load increases and the ripple component increases.
In the embodiment, when the load is an electric motor, the first level and the second level are changed stepwise or continuously with respect to the rotation speed, assuming that the rotation speed corresponds to the magnitude of the load.

According to a fourth aspect of the present invention, in the power supply according to the third aspect, the switching operation control means performs control by changing the first level and the second level in accordance with an input current reflecting a load amount. Device.

In the present invention, the input current detected by the current detection means reflects the load amount. Therefore, the switching operation control means changes the first level and the second level in accordance with the input current. As a result, the switching operation is prevented from being stopped even if the load increases and the ripple component increases, as in the third aspect of the present invention. Further, it is not necessary to provide a new means for detecting the load amount.

According to a fifth aspect of the present invention, in the third aspect, the switching operation control means performs control by changing the first level and the second level in accordance with the target current effective value reflecting the load amount. It is a related power supply device.

In the present invention, the effective value of the target current set by the switching operation control means reflects the load amount. Therefore, the switching operation control means sets the first level and the effective level corresponding to the target current effective value. By controlling by changing the second level, a situation in which the switching operation is stopped even if the load increases and the ripple component increases is prevented, as in the present invention according to claim 3. Further, it is not necessary to provide a new means for detecting the load amount.

According to a sixth aspect of the present invention, the switching operation control means performs control by changing the first level and the second level within a half cycle of the AC power supply. It is a power supply device related to either.

In the present invention, the first level and the second level are changed within a half cycle of the AC power supply, thereby changing the first level and the second level in synchronization with a ripple component having a frequency twice as high as the frequency of the AC power supply. , The amplitude of the change can be made to correspond to the load amount. Thus, the fluctuation range of the DC voltage at the time of light load is suppressed between the first level and the second level, and when the load amount increases, the instantaneous value of the DC voltage including the ripple component and the first level Is always kept at a constant value to prevent the switching operation from being stopped.

The present invention according to claim 7 is the power supply device according to any one of claims 1 to 6, wherein either a microcomputer or a digital signal processor is used for the switching operation control means.

In the present invention, the microcomputer or the digital signal processor executes each control operation in the switching operation control means by an operation according to a program, realizes a configuration that is more compact than the configuration using individual components, and has an excellent arithmetic function. Control is performed quickly, and arbitrary setting of constants for control is facilitated.

According to an eighth aspect of the present invention, there is provided a power supply device according to any one of the first to seventh aspects, and a DC voltage output from an AC / DC conversion circuit in the power supply device is converted into an AC voltage for driving a motor. This is a motor drive device including an inverter for converting.

In the present invention, the power supply of the present invention supplies a stable DC voltage, and the inverter converts the DC voltage into a stable AC voltage to drive the motor, thereby preventing rotation unevenness and step-out.

According to a ninth aspect of the present invention, there is provided an air conditioner configured to drive a motor for a compressor by the motor driving device according to the eighth aspect.

In the present invention, the motor driving device according to the present invention drives the compressor motor with a stable AC voltage.

Hereinafter, embodiments of the present invention will be described.

[0046]

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. This embodiment relates to claim 1.

FIG. 1 is a block diagram showing the configuration of this embodiment. The same components as those in the conventional example are denoted by the same reference numerals.

In FIG. 1, the AC / DC converter shown in the upper part of the figure rectifies the output of an AC power supply 1 by a rectifier circuit 2 using a diode bridge, and converts a voltage obtained by the rectifier circuit 2 through a reactor 3 into a switching element. 4 to switch the voltage across the switching element 4 to a diode 5
, And is supplied to the load 7 after being smoothed by the smoothing capacitor 6. The AC / DC converter includes a current detector 8 for detecting an input current flowing through the AC / DC converter, an input voltage detector 9 for detecting an AC power supply voltage, and a DC voltage output from the AC / DC converter. DC voltage detecting means 10 is provided.

The operation of the switching element 4 is controlled by the switching operation control means 11. First, the DC voltage obtained by the DC voltage detecting means 10 becomes a DC voltage smoothed by the low-pass filter 12 having a low cutoff frequency. This is to eliminate a ripple component having a frequency twice as high as the AC power supply frequency, as shown in FIG. 2B, which is generated due to the characteristics of the AC / DC converter. For example, if the control operation is performed while the ripple component is included, the ripple component is redundant in the target current effective value, and finally the input current waveform is distorted. Further, the DC voltage obtained by the DC voltage detecting means 10 is also input to the PWM output determining means 19.

Next, the voltage comparing means 14 compares the smoothed DC voltage with the predetermined target DC voltage set by the target voltage calculating means 13 to obtain a voltage difference value. Next, the target current effective value calculating means 15 obtains a target current effective value by multiplying the voltage difference value and the voltage gain. Next, the target current instantaneous value calculating means 16 normalizes the AC power supply voltage obtained by the input voltage detecting means 9,
The target value is multiplied by the target current effective value to obtain a target current instantaneous value. Next, the current comparing means 17 compares the above-mentioned target instantaneous value with the input current obtained by the current detecting means 8 to obtain a current difference value. Next, the PWM duty calculating means 18 calculates a pulse width for turning on the switching element 4 by multiplying the current difference value by the current gain. Finally, the PWM output determination means 19 determines that the PWM
Whether to perform the switching operation with the pulse width obtained by the duty calculating means 18 is determined based on a control operation command or the like.

The present embodiment is different from the conventional example in that the switching operation control means 11 for performing the above control regulates the lower limit value of the target current effective value calculated by the target current effective value calculation means 15 and also controls the PWM output. Judgment means 19
As a condition for determining whether or not to perform the switching operation in
The condition that the switching operation is stopped when the DC voltage obtained by the DC voltage detecting means 10 becomes equal to or higher than a first level higher than a predetermined target DC voltage, and the first DC voltage is higher than the predetermined target DC voltage The condition that the switching operation is restarted when the voltage falls below the second level, which is less than the second level, is provided.

In the specific example shown in FIGS. 3 and 4,
The AC power supply voltage is 100 V, the predetermined target DC voltage of the DC voltage is 170 V, the first level at which the switching operation is stopped is 200 V, the second level at which the switching operation is restarted is 195 V, and the lower limit of the target effective value is 1 A. The operation at the time of light load when the value is set will be described.

Even at a light load when the load 7 does not require an effective current value of 1 A or more, the target effective current value is forcibly set to a value of 1 A by the lower limit value regulation.
The DC voltage is boosted to a target DC voltage of 170 V or more. When the boosting proceeds and reaches the first level of 200 V, the switching operation is stopped once, so that the DC voltage decreases. When the voltage drops to the second level of 195 V, the switching operation is restarted, and the DC voltage is increased again. Since this operation is repeated, the fluctuation range of the DC voltage is 5V. If the load 7 needs 1 A or more as the effective value of the current, as shown in FIG.
The DC voltage of 5V to 200V is the target DC voltage of 170V.
Converges to V. As described above, the fluctuation of the DC voltage at the time of light load can be suppressed between the first level and the second level, which can be arbitrarily set, and the fluctuation width of the DC voltage can be reduced accordingly. Thus, it is possible to automatically converge to the target DC voltage without determining the state of the load.

As described above, according to the present embodiment, in the method of completely stopping the switching operation at a light load described in the conventional example, an arbitrary DC voltage can be set depending on the AC power supply voltage while the switching operation is stopped. In the method of stopping the switching operation when the difference between the DC voltage and the target DC voltage becomes equal to or more than a predetermined threshold value, the fluctuation range of the DC voltage is affected by the delay time due to the low-pass filter. It is possible to solve the problem that the DC voltage is not less than the value, and to suppress the fluctuation of the DC voltage between the first level and the second level when the load is light.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to the drawings. This embodiment corresponds to claim 2
Related to

FIG. 5 is a block diagram showing the configuration of this embodiment. The same components as those in the first embodiment are denoted by the same reference numerals.

This embodiment differs from the first embodiment in that, as shown in FIG. 5, the AC power supply voltage obtained by the input voltage detecting means 9 is input to the PWM output determining means 19, and the DC voltage is changed to the second voltage. , And the switching operation is restarted at the zero-cross timing of the AC power supply voltage. Other operations are the same as in the first embodiment.

In the switching operation control means 11,
In the target current effective value calculating means 15, as in the first embodiment,
The lower limit of the target current effective value is regulated. In the present embodiment, as shown in the flowchart of FIG. 6, the DC voltage obtained by the DC voltage detecting means 10 includes a predetermined target DC voltage as a condition for determining whether or not to perform the switching operation in the PWM output determining means 19. The condition that the switching operation is stopped when the voltage becomes equal to or higher than the first level higher than the voltage, and the condition that the input voltage detecting means 9 obtains the voltage lower than the second level which is higher than the predetermined target DC voltage and lower than the first level and lower than A condition is provided that the switching operation is restarted at the zero cross timing of the AC power supply voltage determined from the AC power supply voltage. As a specific example, the input voltage detection means 9 divides the voltage obtained by the rectifier circuit 2 by the diode bridge by resistance and outputs the divided voltage. The PWM output determination means 19 determines the timing at which the divided voltage becomes 0 by using the AC. It is recognized as the zero cross timing of the power supply voltage.

Thereafter, similarly to the first embodiment, the AC power supply voltage is 100 V, and as shown in FIG. 3, the target DC voltage of the predetermined DC voltage is 170 V, and the first operation for stopping the switching operation is performed.
The operation at the time of light load when the level is 200 V, the second level is 195 V, and the lower limit of the target current effective value is 1 A will be described.

FIG. 6 is a flowchart showing the operation of the present embodiment, and FIG. 7 is a waveform diagram showing the operation of the present embodiment at a light load. Even at a light load where the load 7 does not require an effective current value of 1 A or more, the target current effective value is forcibly set to a value equivalent to 1 A due to the lower limit value regulation.
The DC voltage is boosted to a target DC voltage of 170 V or more. When the boosting proceeds and reaches 200 V, the switching operation is stopped once, so that the DC voltage falls. 195V
Then, the PWM output determination means 19 waits for the zero-cross timing of the AC power supply voltage of the AC power supply 1 to be recognized, and when it is recognized, restarts the switching operation, and the DC voltage is boosted again. While waiting for the zero-cross timing of the AC power supply voltage, as shown in FIG. 7C, the DC voltage continues to decrease slightly, but the decrease is gradual due to the light load, and the decrease value from 195 V is almost ignored. It was possible. Since the above operation is repeated, the fluctuation range of the DC voltage is approximately 5V.

As described above, according to the present embodiment, the switching operation is restarted at the zero-cross timing of the AC power supply voltage determined from the AC power supply voltage obtained by the input voltage detecting means 9, so that the switching operation is sharply restarted. Inrush current no longer flows.

FIG. 8 is a circuit diagram showing another configuration of the input voltage detecting means 9. As shown in FIG. 8, a photocoupler 9a is connected to the output line of the AC power supply 1, and a photocoupler 9a is connected to the secondary side of the photocoupler 9a. You may comprise so that a voltage may be made into a detection result.

Embodiment 3 Hereinafter, Embodiment 3 of the present invention will be described with reference to the drawings. This embodiment is claim 3
Related to

FIG. 9 is a block diagram showing the configuration of this embodiment. The same components as those in the first embodiment are denoted by the same reference numerals.

This embodiment is different from the first and second embodiments in that, as shown in FIG. 9, an inverter 20 for converting a DC voltage output from an AC / DC converter into an AC voltage,
The load 7 is formed by the motor 21 connected to the inverter 20, and the switching operation control unit 11 includes a rotation speed detection unit 22 for detecting the rotation speed of the motor 21, and sets the first level and the second level to the rotation speed. It is to control by changing according to the number.

The operation in the above configuration will be described.
Since the fluctuation range of the DC voltage at the time of light load is smaller than that of the conventional example, the power supply device of the present invention can drive the electric motor 21 to a state where the rotation unevenness and the step-out probability are small. At this time, the rotation speed of the electric motor 21 obtained by the rotation speed detection unit 22 is input to the PWM output determination unit 19 and is treated as information on the load amount. That is, when the rotation speed of the electric motor 21 is large, the load amount is large, and when the rotation speed is small, the load amount is small.

The PWM output determining means 19 changes the first level of the DC voltage at which the switching operation is stopped and the second level at which the switching operation is restarted according to the rotation speed of the electric motor 21, that is, the load amount. Let it. This is because the DC voltage output from the AC / DC conversion circuit has a ripple component having a frequency twice as high as the AC power supply frequency, and its width changes in proportion to the load amount. When the ripple component of the DC voltage increases due to the increase, the margin between the DC voltage and the first level is secured so that the switching operation is not unintentionally stopped due to the influence of the ripple component. .

FIG. 10 is a waveform diagram showing an operation when the margin is not secured. For example, as shown in FIG.
If the first level at which the switching operation is stopped is 180 V and the second level at which the switching operation is restarted is 175 V in order to make the DC voltage at light load as close as possible to the target DC voltage as much as possible, the motor The DC voltage is 175 V to 180 V before the rotation of the motor 21 or at a light load when the rotation speed is small. However, when the rotation speed of the electric motor 21 increases, the ripple component of the DC voltage increases, and the peak value of the ripple component is 1 which is the first level.
When the voltage exceeds 80 V, the switching operation stops, and the waveform of the input current flowing through the AC / DC converter is distorted.

However, in this embodiment, as shown in FIG. 11, by changing the first level and the second level of the DC voltage in accordance with the rotation speed of the electric motor 21, that is, the load amount, DC voltage is 175V ~ 180 at light load
V, while maintaining the DC voltage as close as possible to the target DC voltage 170 V, and when the load becomes large, for example,
When the rotation speed of the motor 21 is 50 Hz or more, the first level is 200 V, and the ripple component of the DC voltage is 20 V.
Even at Vpp, a margin of 20 V is secured so that the switching operation is not stopped.

It is more preferable that the first level and the second level of the DC voltage are continuously changed as shown in FIG. In a system in which the target DC voltage of the DC voltage changes, the first level is set to (target DC voltage +
α), the second level is (target DC voltage + β), and the threshold value α and the threshold value β can be changed as shown in FIG.

As described above, according to the present embodiment, by changing the first level and the second level in accordance with the load, the DC voltage and the first level when the load is large are different. A margin can be secured to prevent the switching operation from being stopped based on the influence of the ripple component.

Embodiment 4 Hereinafter, Embodiment 4 of the present invention will be described with reference to the drawings. This embodiment is claim 4
Related to

FIG. 14 is a block diagram showing the configuration of this embodiment. The same components as those of the third embodiment are denoted by the same reference numerals. This embodiment is different from the third embodiment in that the first level and the second level are controlled by changing the first level and the second level in accordance with the input current corresponding to the load amount instead of the load amount. .

In FIG. 14, the input current obtained by the current detecting means 8 is proportional to the power consumption of the load 7, that is, the load amount if the voltage of the AC power supply 1 is fixed. Therefore, paying attention to the fact that the input current corresponds to the load amount, in the present embodiment, a value obtained by calculating the average of the input current in place of the load amount obtained by the rotation speed detecting means 22 in the third embodiment is used,
The first level of the DC voltage at which the switching operation is stopped and the second level at which the switching operation is restarted are changed.

That is, the input current obtained by the current detecting means 8 is input to the PWM output determining means 19, and the PWM output determining means 19 calculates the average of the input current flowing through the AC / DC converter circuit. As shown in (1), the first level and the second level were changed.

As described above, according to the present embodiment, the third embodiment
It is no longer necessary to newly provide a means for detecting the load amount such as the rotation number detecting means 22 in the above.

In this embodiment, the load amount is the average value of the input current obtained by the current detecting means 8, but it is needless to say that the effective value or the peak value of the input current may be used.

Embodiment 5 Hereinafter, Embodiment 5 of the present invention will be described with reference to the drawings. This embodiment is defined by claim 5
Related to

FIG. 16 is a block diagram showing the configuration of this embodiment. The same components as those of the third embodiment are denoted by the same reference numerals. The present embodiment is different from the third embodiment in that the first level and the second level are controlled by changing the first level and the second level in accordance with the target current effective value corresponding to the load amount instead of the load amount. It is in.

Referring to FIG. 16, in the present embodiment, attention is paid to the fact that the target effective current value obtained by the switching operation control means 11 corresponds to the load amount, and the load obtained by the rotation speed detection means 22 of the third embodiment. The target current effective value is used in place of the amount, and the first level and the second level are set corresponding to the target current effective value.
And try to change the level. That is, the target current effective value obtained by the target current effective value calculation means 15 is input to the PWM output determination means 19, and the first level and the second level are changed according to the target current effective value.

As described above, according to the present embodiment, the fourth embodiment
Similarly to the above, it is not necessary to newly provide a means for detecting the load amount such as the rotation speed detecting means 22 in the third embodiment.

(Embodiment 6) Hereinafter, Embodiment 6 of the present invention will be described with reference to the drawings. This embodiment is claim 6
Related to

FIG. 17 is a waveform chart showing the operation of this embodiment. This embodiment is different from the third and fourth embodiments in that, as shown in FIG. 17, the first level of the DC voltage for stopping the switching operation and the second level for restarting the switching operation are set to the alternating current. The control is performed by changing the voltage so as to match the fluctuation of the ripple component having a frequency twice as high as the AC power supply frequency included in the DC voltage during a half cycle of the power supply 1.

This is because the time of the zero-cross timing interval of the AC power supply voltage determined from the AC power supply voltage obtained by the input voltage detecting means 9 is measured, and the first level and the first level are changed with the lapse of time in the next zero-cross timing interval. It was realized by the method of changing between the two levels. Thus, it is possible to secure a constant value between the DC voltage including the ripple component and the first level at which the switching operation is stopped at any timing when the load amount increases.

As described above, according to the present embodiment, the DC voltage including the ripple component and the first operation in which the switching operation stops.
By ensuring a constant margin at any point in time, the situation in which the switching operation stops when the load amount increases can be accurately prevented.

(Embodiment 7) Hereinafter, Embodiment 7 of the present invention will be described. This embodiment relates to claim 7.

In this embodiment, the control by the switching operation control means 11 is entirely digital control performed by a microcomputer. By realizing a series of arithmetic processing by a program of a microcomputer, it was possible to systematize the system very easily as compared with the case where it was configured by a combination of electronic circuits.

(Embodiment 8) An embodiment 8 of the present invention will be described below. This embodiment relates to claim 7.

In the present embodiment, the control by the switching operation control means 11 is all digital control performed by a digital signal processor. By realizing a series of arithmetic processing by a program of a digital signal processor, it was possible to systematize the system very easily as compared with a case where it was configured by a combination of electronic circuits. In particular, digital signal processors have built-in multipliers,
Since the product-sum operation is performed very quickly, it is possible to achieve a configuration that is not easily restricted by the operation processing time.

(Embodiment 9) Hereinafter, Embodiment 9 of the present invention will be described. This embodiment relates to claims 8 and 9.

In this embodiment, an inverter is provided at the output of the power supply device according to any of the third to eighth embodiments to form a motor drive device, and the motor drive device is mounted on an air conditioner.

Since the load of the compressor motor of an air conditioner greatly changes depending on the state of the refrigeration cycle, it is necessary to supply a stable DC voltage to the inverter for driving the motor. The fluctuation range of the DC voltage was reduced, and in particular, the starting of the compressor motor was ensured, and stable rotation with little fluctuation in the number of revolutions after the start was realized.

[0093]

According to the first aspect of the present invention, there is provided an AC / DC conversion circuit that includes at least a switching element, a reactor, and a diode and obtains a DC voltage from an AC power supply by a switching operation of the switching element. Current detection means for detecting an input current flowing through
Input voltage detection means for detecting an AC power supply voltage of the AC power supply, DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit, the input current, the AC power supply voltage, and the DC voltage Switching operation control for controlling the operation of the switching element so as to improve the power factor while calculating the target current effective value and the target current instantaneous value of the input current, and so that the DC voltage becomes a predetermined target DC voltage. Means, the switching operation control means restricts the target current effective value to a lower limit value, and stops the switching operation when the DC voltage is equal to or higher than a first level higher than the predetermined target DC voltage. The switching is performed when the DC voltage falls below a second level which is higher than the predetermined target DC voltage and lower than the first level. With the power supply device for controlling to restart the work, an effect called fit between the first level DC voltage under light load is arbitrarily set and a second level. Further, there is an effect that the convergence to the target DC voltage is automatically performed without determining the state of the load.

According to a second aspect of the present invention, there is provided an AC / DC conversion circuit which includes at least a switching element, a reactor, and a diode, and obtains a DC voltage from an AC power supply by a switching operation of the switching element, and flows to the AC / DC conversion circuit. Current detection means for detecting an input current; input voltage detection means for detecting an AC power supply voltage of the AC power supply; DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit; From the AC power supply voltage and the DC voltage, to improve the power factor while calculating the target current effective value and the target current instantaneous value of the input current, and so that the DC voltage becomes a predetermined target DC voltage. Switching operation control means for controlling an operation of a switching element, wherein the switching operation control means While regulating the flow effective value to the lower limit, the switching operation is stopped when the DC voltage is equal to or higher than a first level higher than the predetermined target DC voltage, and the DC voltage is higher than the predetermined target DC voltage. 2. The effect of the present invention according to claim 1, wherein the power supply device controls the switching operation to be restarted at a second level which is lower than the first level and at a zero cross timing of the AC power supply voltage. In addition, there is an effect that a steep rush current does not flow when the switching operation is restarted.

According to a third aspect of the present invention, the switching operation control means performs control by changing the first level and the second level in accordance with the amount of load connected to the output of the AC / DC conversion circuit. By providing the power supply device according to any one of the first and second aspects, the effect of the present invention according to the first or second aspect is provided, and when the load amount increases and the ripple component of the DC voltage increases. This also has an effect that a margin between the DC voltage for stopping the switching operation and the first level can be secured. Also, there is an effect that the DC voltage at the time of light load can be made as close as possible to the target DC voltage.

According to a fourth aspect of the present invention, in the power supply according to the third aspect, the switching operation control means performs control by changing the first level and the second level in accordance with an input current reflecting a load amount. Claim 3
In addition to the effect of the present invention, there is no need to newly provide a means for detecting the load amount, so that the system can be reduced in size and weight and cost can be reduced.

According to a fifth aspect of the present invention, in the third aspect, the switching operation control means performs control by changing the first level and the second level in accordance with the target current effective value reflecting the load amount. With the power supply device concerned, not only the effect of the present invention according to claim 3 but also the necessity for newly providing a means for detecting the load amount is not required, and the effect that the system can be reduced in size and weight and the cost can be achieved is achieved.

According to a sixth aspect of the present invention, the switching operation control means controls by changing the first level and the second level within a half cycle of the AC power supply. By providing the power supply device according to any one of the first to fifth aspects, in addition to the effect of the present invention according to any one of the first to fifth aspects, when the load amount increases, the DC voltage including the ripple component and the switching operation stop. Is maintained at a constant value at any timing, that is, the over-boost width of the DC voltage is constant even if the load is suddenly reduced, which also has the effect of improving the operation reliability of the system. .

According to a seventh aspect of the present invention, there is provided a power supply unit according to any one of the first to sixth aspects, wherein any one of a microcomputer and a digital signal processor is used as the switching operation control means.
In addition to the effects of the present invention according to any one of claims 1 to 6, the number of parts can be reduced as compared with the case where the electronic circuit is configured as a combination, and the system can be extremely easily systemized.

According to an eighth aspect of the present invention, there is provided a power supply according to any one of the first to seventh aspects, and a DC voltage output from an AC / DC conversion circuit in the power supply for driving a motor. By using a motor drive device equipped with an inverter that converts to AC voltage, it is possible to prevent uneven rotation and step-out of the motor, and to start the motor under conditions where the DC voltage fluctuates little. The effect of improving is also achieved.

According to a ninth aspect of the present invention, there is provided an air conditioner configured to drive a motor for a compressor by the motor driving device according to the eighth aspect, thereby achieving the effects of the eighth aspect of the present invention. Since the DC voltage can be set to the preset target DC voltage even when the compressor motor is stopped, there is also an effect that the control of the blower motor and other actuators of the air conditioner can be stably performed. Play.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a waveform chart showing input / output voltages of an AC / DC converter in the embodiment.

FIG. 3 is a waveform chart showing an operation at a light load in the embodiment.

FIG. 4 is a waveform chart showing the operation of the embodiment.

FIG. 5 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of the embodiment.

FIG. 7 is a waveform chart showing an operation at a light load in the embodiment.

FIG. 8 is a circuit diagram showing another configuration of the input voltage detecting means in the embodiment.

FIG. 9 is a block diagram showing a configuration of a third embodiment of the present invention.

FIG. 10 is a waveform chart showing an operation in a state where a margin between a DC voltage and a first level is not secured in the embodiment.

FIG. 11 is a characteristic diagram showing changes in a first level and a second level in the embodiment.

FIG. 12 is a characteristic diagram showing another change of the first level and the second level in the embodiment.

FIG. 13 is a characteristic diagram showing changes in threshold values α and β in the embodiment.

FIG. 14 is a block diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 15 is a characteristic diagram showing changes in a first level and a second level in the embodiment.

FIG. 16 is a block diagram showing a configuration of a fifth embodiment of the present invention.

FIG. 17 is a characteristic diagram showing changes in a first level and a second level in Embodiment 6 of the present invention.

FIG. 18 is a block diagram showing a configuration of an example of a power supply device using a conventional AC / DC conversion circuit.

FIG. 19 is a flowchart showing a control operation of the conventional example.

FIG. 20 is a waveform chart showing an operation at a light load of the conventional example.

[Explanation of symbols]

 Reference Signs List 1 AC power supply 2 Rectifier circuit 3 Reactor 4 Switching element 5 Diode 6 Smoothing capacitor 7 Load 8 Current detection means 9 Input voltage detection means 9a Photocoupler 10 DC voltage detection means 11 Switching operation control means 12 Low-pass filter 13 Target voltage calculation means 14 Voltage comparing means 15 Target current effective value calculating means 16 Target current instantaneous value calculating means 17 Current comparing means 18 PWM duty calculating means 19 PWM output determining means 20 Inverter 21 Motor 22 Revolution detecting means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masanori Ogawa 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 5H006 AA01 AA02 AA05 BB05 CA02 CA07 CB01 CB08 CC08 DA04 DB01 DB07 DC02 DC05 FA01 FA02 5H576 AA10 BB01 BB03 BB04 CC05 DD02 DD04 EE11 EE18 FF01 HA02 HB02 JJ03 LL01 LL22 LL24 MM02

Claims (9)

[Claims] 1. An AC / DC conversion circuit including at least a switching element, a reactor, and a diode and obtaining a DC voltage from an AC power supply by a switching operation of the switching element, and a current detection detecting an input current flowing through the AC / DC conversion circuit. Means, input voltage detection means for detecting an AC power supply voltage of the AC power supply, DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit, the input current, the AC power supply voltage, and the DC voltage Controlling the operation of the switching element so as to improve the power factor while calculating the target current effective value and the target current instantaneous value of the input current, and so that the DC voltage becomes a predetermined target DC voltage. Switching operation control means, wherein the switching operation control means regulates a lower limit of the target current effective value. And when the DC voltage is equal to or higher than a first level higher than the predetermined target DC voltage, the switching operation is stopped, and the DC voltage is higher than the predetermined target DC voltage and lower than the first level. A power supply device that controls the switching operation to be resumed when the voltage falls below level 2. 2. An AC / DC conversion circuit including at least a switching element, a reactor, and a diode, for obtaining a DC voltage from an AC power supply by a switching operation of the switching element, and a current detection for detecting an input current flowing through the AC / DC conversion circuit. Means, input voltage detection means for detecting an AC power supply voltage of the AC power supply, DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit, the input current, the AC power supply voltage, and the DC voltage Controlling the operation of the switching element so as to improve the power factor while calculating the target current effective value and the target current instantaneous value of the input current, and so that the DC voltage becomes a predetermined target DC voltage. Switching operation control means, wherein the switching operation control means regulates a lower limit of the target current effective value. And when the DC voltage is equal to or higher than a first level higher than the predetermined target DC voltage, the switching operation is stopped, and the DC voltage is higher than the predetermined target DC voltage and lower than the first level. A power supply device that controls the switching operation to resume at a level of 2 or less and at a zero-cross timing of the AC power supply voltage. 3. The switching operation control means controls the first and second levels by changing the first level and the second level in accordance with the amount of load connected to the output of the AC / DC conversion circuit.
The power supply device according to claim 2. 4. The power supply device according to claim 3, wherein the switching operation control means performs control by changing the first level and the second level in accordance with the input current reflecting the load amount. 5. The power supply device according to claim 3, wherein the switching operation control means controls the first and second levels by changing the first level and the second level in accordance with the target current effective value reflecting the load amount. 6. The power supply device according to claim 1, wherein the switching operation control means controls the first level and the second level by changing the first level and the second level within a half cycle of the AC power supply. . 7. The power supply device according to claim 1, wherein one of a microcomputer and a digital signal processor is used as the switching operation control means. 8. A power supply device according to claim 1, further comprising an inverter for converting a DC voltage output from an AC / DC conversion circuit in the power supply device into an AC voltage for driving a motor. Motor drive. 9. An air conditioner configured to drive a motor for a compressor by the motor drive device according to claim 8.