JP2001320882A - Power supply apparatus, inverter and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply apparatus which can control an excessive input voltage inputted in an abnormal state of an AC power supply voltage and to provide an inverter and an air conditioner in which the apparatus is used. SOLUTION: A switching operation control means 11 controls operations of switching devices 4a and 3b so as to improve a power factor and set a DC voltage outputted to a load 7 to a predetermined target DC voltage. If a pulse width and a pulse interval of a pulse signal outputted from a voltage polarity detection means 20 in synchronism with an AC power supply 1 and corresponding to the voltage polarity of eh power supply 1 are out of predetermined ranges corresponding to the AC power supply frequency, the control means 11 controls the switching operations to stop. Further, after the operations are stopped, it controls the switching operations to r-start at the zero-cross timing of the AC power supply voltage. With this constitution, an excessive input current corresponding to the abnormal state of the AC power supply voltage can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, with the spread of home electric appliances and industrial equipment, harmonic currents have flowed into a power system, and problems such as heat generation and malfunction of various devices have come to occur. In response to these problems, various devices require measures against harmonics, and the power supplies in the devices use the energy storage effect of the operation of the reactors and switching elements to improve the power factor and output power. An AC / DC converter circuit for increasing a voltage has been used.

FIG. 13 is a block diagram showing the configuration of the conventional power supply device. In FIG. 13, 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 reactor 3, the switching element 4, the diode 5, and the smoothing capacitor 6 constitute an AC / DC conversion circuit.

The operation of the above configuration will be described.
In the DC voltage obtained by the DC voltage detecting means 10, a ripple component having a frequency twice as high as the AC power supply frequency as shown in FIG. 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 calculates and sets a target DC voltage of the DC voltage. Voltage comparison means 14
Calculates a voltage difference value by comparing the smoothed DC voltage with the predetermined target DC voltage. The target current effective value calculating 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 AC power supply voltage obtained by the input voltage detection means 9 and multiplies the AC power supply voltage by the target current effective value to obtain a target current instantaneous value.

The current comparing means 17 compares the instantaneous target current value with the input current obtained by the current detecting means 8 to obtain a current difference value. The PWM duty calculator 18 multiplies the current difference value by the current gain to calculate a duty for turning on the switching element. PWM
The output determination unit 19 determines whether to perform a switching operation at the duty 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.

FIG. 14 is a block diagram showing another configuration of a conventional power supply device. As shown in FIG. 14, in the AC / DC conversion circuit, instead of using the input voltage detecting means 9 in FIG. 13, a voltage polarity detecting means 20 which outputs a pulse signal based on the voltage polarity in synchronization with the cycle of the AC power supply. The target current instantaneous value calculation means 16 obtains a normalized value of the AC power supply voltage from the pulse signal, and multiplies the obtained value by the target current effective value to obtain a target current instantaneous value.
In this conventional example, the voltage polarity detecting means 20 is used in place of the input voltage detecting means 9 so that an input voltage detecting means such as a transformer 21 for voltage conversion and a diode bridge 22 for rectification as shown in FIG. 9 is simpler than that of the circuit using No. 9, and the problem that the circuit is enlarged is solved.

[0007]

In such a conventional power supply device, when the pulse signal output from the voltage polarity detecting means 20 is not in a normal state due to an instantaneous interruption of the AC power supply 1, the AC power supply 1 The normalized value of the AC power supply voltage cannot be obtained correctly. Further, the target current instantaneous value and the duty for turning on the switching elements 4a and 4b do not become normal values. For example, the pulse signal output from the voltage polarity detection means 20 is the AC power supply 1
When the level changes at the same time as the zero-cross timing of the AC power supply voltage, and a normalized value of the AC power supply voltage is obtained based on the level change, the pulse signal output from the voltage polarity detection means 20 due to an instantaneous power failure or the like is shown in FIG. 16
In the case shown in (b), the normalized value of the AC power supply voltage of the AC power supply 1 is not synchronized with the AC power supply voltage of the AC power supply 1.

Normally, as shown in FIG. 16 (c), the duty at which the switching elements 4a and 4b are turned on is most likely to occur at the zero-cross timing when the normalized value of the AC power supply voltage of the AC power supply 1 becomes 0. Since the calculation is performed so as to increase, the input current flowing in the AC / DC conversion circuit after the recovery from the instantaneous power failure becomes as shown in FIG.
It will be too large.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a power supply device capable of preventing an excessive current at the time of abnormal voltage of an AC power supply voltage while reducing the size and cost of a circuit, and an inverter device using the same. And an air conditioner.

[0010]

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. Voltage polarity detection means for outputting a pulse based on the polarity of the power supply voltage; and switching operation control means for controlling the operation of the switching element, wherein the switching operation control means improves the power factor and reduces the DC voltage. When controlling the switching operation by setting the target current effective value and the target current instantaneous value of the input current flowing in the AC / DC conversion circuit so as to obtain, the pulse width or pulse interval of the pulse signal falls within a predetermined range. This is a power supply device that controls so as to stop the switching operation if it does not fit.

According to the present invention, an excessive current can be prevented when the AC power supply voltage is abnormal.

According to a second aspect of the present invention, the switching operation control means calculates a zero-cross timing of the AC power supply voltage from the pulse width and the pulse interval of the pulse signal, and the pulse width or the pulse interval falls within a predetermined range. The power supply device according to claim 1, wherein the switching operation is controlled so as to be restarted at the zero-cross timing after the switching operation is stopped.

According to the present invention, an excessive input current at the time of restarting the switching operation can be prevented.

The present invention according to claim 3 is the power supply device according to any one of claims 1 and 2, wherein either a microcomputer or a digital signal processor is used for the switching operation control means.

According to the present invention, excellent arithmetic functions can be utilized, the configuration is simpler than that of a separate circuit, and the setting of constants for control can be facilitated.

According to a fourth aspect of the present invention, the pulse width and the pulse interval of the pulse signal are measured by counting the number of switching operations of the switching element performed during the pulse width period and the pulse interval period, respectively. A power supply device according to claim 3 configured as described above.

According to the present invention, the pulse width and the pulse interval can be indirectly measured other than the time measurement, and the necessity of using timer means can be eliminated.

According to a fifth aspect of the present invention, there is provided a power supply according to any one of the first to fourth aspects, and a DC / AC conversion circuit for converting a DC voltage output from the power supply into an AC voltage. And an inverter device comprising:

According to the present invention, it is possible to realize an inverter device that can prevent an excessive input current when the AC power supply voltage is abnormal and output a stable AC voltage.

According to a sixth aspect of the present invention, there is provided an air conditioner configured to drive a motor for a compressor using the inverter device according to the fifth aspect of the present invention.

According to the present invention, it is possible to realize an air conditioner that operates stably by preventing an excessive input current when the AC power supply voltage is abnormal.

[0022]

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 in the conversion circuit, voltage polarity detection means for outputting a pulse signal based on a voltage polarity in synchronization with a cycle of the AC power supply, and a DC voltage output by the AC / DC conversion circuit. DC voltage detecting means for detecting, and a target of an input current to be flown to the AC / DC conversion circuit from a pulse signal output from the voltage polarity detecting means or each value obtained by the current detecting means and the DC voltage detecting means. In order to improve the power factor while calculating the current effective value and the target current instantaneous value, and to reduce the DC voltage to a predetermined target DC voltage Switching operation control means for controlling the operation of the switching element, wherein the switching operation control means stops the switching operation if the pulse width or pulse interval of the pulse signal does not fall within a predetermined range. Device.

In the present invention, the voltage polarity detection means is a means for outputting a pulse signal based on the polarity of the AC power supply voltage, and the voltage polarity detection means is provided at a zero cross timing of the AC power supply voltage.
In addition to the configuration for outputting a pulse signal that changes between a gh level and a low level, the present invention is not limited to the zero-cross timing.
Also includes a configuration that outputs a pulse signal at a timing corresponding to a predetermined offset voltage.In any case, when the AC power supply voltage is abnormal, for example, during a momentary power failure, the pulse width and pulse interval are output differently from those at normal times. We pay attention to being done. The configuration for outputting the pulse signal as described above can be simpler than the configuration for detecting the power supply voltage waveform in an analog manner, for example, the configuration using a transformer or a rectifier circuit. If the pulse width or pulse interval of the pulse signal output from the voltage polarity detection unit does not fall within a predetermined range, the switching operation control unit determines that an abnormality has occurred in the AC power supply voltage, and stops the switching operation of the switching element. This prevents an excessive current when the AC power supply voltage is abnormal due to an instantaneous interruption of the AC power supply.

According to a second aspect of the present invention, the switching operation control means calculates the zero-cross timing of the AC power supply voltage from the pulse width and the pulse interval of the pulse signal output from the voltage polarity detection means, and calculates the pulse width or the pulse width. The power supply device according to claim 1, wherein restart of the switching operation after a pulse interval falls within a predetermined range is performed at the zero-cross timing.

In the present invention, the switching operation control means calculates a zero cross timing of the AC power supply voltage,
By restarting the switching operation at that timing, an excessive power supply is prevented from flowing even when the switching operation is restarted. When the voltage polarity detection means outputs a pulse signal whose level changes at the zero cross timing, the timing of the level change of the pulse signal becomes the zero cross timing as it is. In the case of a pulse signal whose level changes in response to a predetermined offset voltage of the AC power supply voltage, the zero-cross timing can be calculated from the pulse width and the pulse interval.

The present invention according to claim 3 is the power supply device according to claim 1 or claim 2, 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 the control operation of the switching operation control means including the comparing means and the arithmetic means by means of a program, and can utilize excellent arithmetic functions and facilitate systemization.

According to a fourth aspect of the present invention, the switching operation control means performs the pulse width and the pulse interval of the pulse signal output from the voltage polarity detection means during the pulse width period and the pulse interval period, respectively. The power supply device according to claim 3, wherein the power supply device measures the number of times of switching of the switching element by counting.

In the present invention, the switching operation control means does not measure the pulse width and pulse interval output by the voltage polarity detection means by time, but indirectly measures by the number of switching of the switching element. This eliminates the need to use a timer function of a microcomputer or digital signal processor to measure the pulse width and pulse interval of the pulse signal. In this embodiment, a digital signal processor having a function of generating a PWM output signal in synchronization with an up / down counter is used.

According to a fifth aspect of the present invention, there is provided a power supply unit according to any one of the first to fourth aspects, and a DC / AC conversion circuit for converting a DC voltage output from the power supply unit into an AC voltage. It is an inverter device provided with.

In the present invention, the DC / AC conversion circuit converts a DC voltage output by the power supply device according to any one of claims 1 to 4 into an AC voltage, and copes with an abnormality in the AC power supply voltage. Outputs stable AC voltage.

According to a sixth aspect of the present invention, there is provided an air conditioner in which a motor for a compressor is driven by an AC voltage output from the inverter device according to the fifth aspect of the present invention.

[0033] In the present invention, the air conditioner is characterized in that:
, The motor for the compressor is driven stably.

Hereinafter, embodiments of the present invention will be described.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of the present invention will be described below 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 in the conventional example are denoted by the same reference numerals. The present invention differs from the conventional example in that the switching operation is stopped when the pulse width or the pulse interval of the pulse signal based on the voltage polarity of the AC power supply voltage does not fall within a predetermined range in synchronization with the cycle of the AC power supply 1. It is to have done.

In FIG. 1, in the AC / DC converter shown in the upper part, one output terminal of the AC power supply 1 is connected via a reactor 3 to an upper arm formed by connecting a switching element 4a and a high-speed diode 2a in parallel. , Are connected to a common connection point with the lower arm by the parallel connection of the switching element 4b and the high-speed diode 2b. AC power supply 1
The other output terminal is connected to a common connection point between the rectifier diode 5a and the rectifier diode 5b, and a bridge circuit is formed by connecting these circuits. The smoothing capacitor 6 smoothes the voltage obtained by the bridge circuit and supplies it to the load 7.

The AC / DC conversion circuit includes an AC power supply 1
A voltage polarity detecting means 20 for outputting a pulse signal based on the voltage polarity in synchronization with the cycle of the current, a current detecting means 8 for detecting an input current flowing to the AC / DC converter, and a DC voltage output from the AC / DC converter. DC voltage detecting means 1 for detecting
0 is arranged respectively. Switching element 4
The operations of a and the switching element 4b are controlled by the switching operation control means 11.

The operation of the above configuration will be described.
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 occurs due to the characteristics of the AC / DC converter. For example, if the control calculation described below 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.

The voltage comparing means 14 compares the smoothed DC voltage with a predetermined target DC voltage to obtain a voltage difference value. Next, the target current effective value calculation means 15 obtains a target current execution value by multiplying the voltage difference value and the voltage gain. Next, the target current instantaneous value calculation means 16 obtains a value obtained by normalizing the voltage of the AC power supply 1 from the pulse signal output from the voltage polarity detection means 20, and multiplies the value by the target current effective value. To obtain the target current instantaneous value. Here, as the configuration of the voltage polarity detection means 20, the output pulse signal is configured to change its level at the same time as the zero-cross timing of the AC power supply voltage of the AC power supply 1, and a value obtained by normalizing the AC power supply voltage of the AC power supply 1 is Vnorm = 2 ^1/2・ ｜ s
in (2π · fac · Tp) |. Where f
ac is the AC power supply frequency, and Tp is the time from the level change of the pulse signal.

The current comparator 17 compares the instantaneous target current value with the current obtained by the current detector 8 to obtain a current difference value. Next, the PWM duty calculating means 18
Multiplies the current difference value and the current gain to calculate the duty to turn on the switching elements 4a and 4b. Finally, the PWM output determination means 19 determines whether to perform the switching operation with the duty obtained by the PWM duty calculation means 18 based on a control operation command or the like.

In this embodiment, the condition for determining whether or not to perform the switching operation in the PWM output determination means 19 includes the pulse width (time from rising to falling) of the pulse signal or the pulse interval (from rising to rising). The condition that the switching operation is stopped unless the time and the time from falling to falling fall within a predetermined range corresponding to the AC power supply frequency is provided.

Specifically, as shown in FIG. 3, when the AC power supply frequency is 50 Hz, the pulse width is 9 to 11 msec.
c, the pulse interval is 18 to 22 msec, and the pulse width is 7.5 to 9.2 m when the AC power supply frequency is 60 Hz.
When the pulse interval deviates from 15 to 18.3 msec, the switching operation is stopped.

The switching operation when this determination condition is added will be described. FIG. 4 is a waveform chart showing the operation of this embodiment. Now, the voltage polarity detection means 29 is configured so that the level of the pulse signal changes at the zero cross timing of the AC power supply voltage of the AC power supply 1. Therefore, if the AC power supply frequency is 50 Hz, the pulse width of the pulse signal is 1
0 ms and the pulse interval is 20 ms. While the pulse signal is normally recognized, a substantially sinusoidal input current with an improved power factor flows through the AC / DC converter.

When the AC power supply 1 has a momentary power failure at the time of a voltage peak, the pulse signal changes from a high level to a low level in accordance with a decrease in the AC power supply voltage. For this reason, the pulse width is 5 msec, which is out of the range determined as normal, that is, 9 to 11 msec.
Here, the switching operation is temporarily stopped. During the period during which the switching operation is stopped, power is supplied to the load 7 by discharging the smoothing capacitor 6, and the input current flowing to the AC / DC converter becomes zero. Next, the pulse signal after the AC power supply 1 recovers from the momentary power failure changes from the Low level to the High level.
When the signal level changes to the h level, the switching operation is restarted because the pulse interval from the rise of the signal to the rise is 20 msec, and a substantially sinusoidal input current with a power factor improved starts to flow through the AC / DC converter.

In such a case, in the conventional example, the input current flowing to the AC / DC converter circuit after the recovery from the instantaneous power failure becomes excessively large. However, in the present embodiment, if an abnormality is recognized in the pulse signal, the pulse signal is temporarily stopped. By stopping the switching operation, an excessive current can be prevented.

As described above, according to the present embodiment, the switching operation is stopped when the pulse width or pulse interval of the pulse signal based on the voltage polarity of the AC power supply does not fall within a predetermined range. Excessive input current generated at the time of abnormal voltage can be prevented.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to the drawings. This embodiment relates to claim 1 as in the first embodiment.

FIG. 5 is a circuit diagram showing the configuration of the voltage polarity detecting means 20 in this embodiment. This embodiment is Embodiment 1.
The difference from this is that the timing of the level change of the pulse signal output from the voltage polarity detection means 20 does not become the zero cross timing of the AC power supply voltage. FIG.
As shown in (1), in the present embodiment, it is composed of a photocoupler 9a, a resistor 9b, and a diode 9c. Diode 9c connected in parallel to the primary side of photocoupler 9a
Is for protecting the photocoupler 9a.

The voltage polarity detecting means 20 having the above configuration has a simple configuration, while the output pulse signal is
6, the level does not change at the zero-cross timing of the AC power supply voltage of the AC power supply 1, as shown in FIG. Therefore, in the first embodiment, the condition that the switching operation is stopped unless the pulse width or the pulse interval of the pulse signal falls within a predetermined range corresponding to the AC power supply frequency is provided. Is determined by the AC power supply frequency, and the range in which the pulse width is normal is determined by the AC power supply frequency and the circuit characteristics of the voltage polarity detection means 20. Controlling.

Specifically, as shown in FIG. 6, a voltage polarity detecting means such that the AC power supply voltage of the AC power supply 1 is 100 V and the pulse signal becomes High during the period when the instantaneous value is 50 V or more. When the circuit characteristic is 20, the pulse width is 7 to 8.6 ms when the AC power supply frequency is 50 Hz.
ec, when the AC power supply frequency is 60 Hz, the switching operation is stopped when the pulse width deviates from 5.8 to 7.1 msec.

As described above, according to the present embodiment, an excessive input current can be prevented when the AC power supply voltage is abnormal, as in the first embodiment, while simplifying the configuration of the voltage polarity detecting means 20. .

Embodiment 3 Hereinafter, Embodiment 3 of the present invention will be described with reference to the drawings. This embodiment is claimed in claim 1
And claim 2.

FIG. 7 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. Further, the voltage polarity detecting means 20 is composed of a photocoupler 9a, a resistor 9b, and a diode 9c as shown in FIG. 5, as in the second embodiment.

This embodiment is different from the first and second embodiments in that the switching operation is stopped and the zero-cross timing calculating means 23 for calculating the zero-cross timing of the AC power supply voltage is provided. Is to resume.

First, as for the condition for stopping the switching operation, the pulse width and the pulse interval are stored for each cycle of the AC power supply 1 and must be within a predetermined range based on the pulse width and the pulse interval of the previous cycle. In this case, the switching operation is stopped. That is, the switching operation is stopped when the pulse width and the pulse interval of the previous cycle greatly deviate. Particularly, in the case of the voltage polarity detecting means 20 composed of the photocoupler 9a, the resistor 9b, and the diode 9c shown in FIG. 6, the pulse width of the pulse signal output due to the aging of the photocoupler 9a becomes short. Even if you do, you can deal with it.

Next, in this embodiment, as shown in FIG. 7, the switching operation control means 11 is provided with a zero cross timing calculating means 23. The zero-cross timing calculating means 23 obtains the AC power supply frequency fac from the pulse interval of the pulse signal, and obtains the zero-cross timing of the AC power supply voltage of the AC power supply 1 from the AC power supply frequency fac and the pulse width Ton of the pulse signal by the following calculation. This is shown in FIG.
As can be seen from FIG. 5, the time is from the falling change of the pulse signal.

Tz1 = ((1 / (2 · fac)) − Ton) / 2 Tz2 = Tz1 + 1 / (2 · fac) The information of the zero-cross timing is input to the PWM output determination means 19, and the PWM output determination means 19 , The switching operation is started at the zero cross timing.

Therefore, as shown in FIG. 6, even when the level of the pulse signal does not change at the zero-cross timing of the AC power supply voltage of the AC power supply 1, the switching operation can be started at the zero-cross timing. Even when the switching operation is restarted after the switching operation is stopped, no sharp inrush current flows.

As described above, according to this embodiment, the switching operation is restarted at the zero-cross timing of the AC power supply voltage, thereby preventing an excessive input current when the AC power supply voltage is abnormal even when the switching operation is restarted. be able to.

(Embodiment 4) Hereinafter, Embodiment 4 of the present invention will be described. This embodiment relates to claim 3.

In this embodiment, the control by the switching operation control means 11 is all digital control performed by a microcomputer. Since a series of arithmetic processing is realized by a microcomputer program, it is possible to systematize the system very easily as compared with the case where it is configured by a combination of electronic circuits, and furthermore, voltage, current gain, filter constant, pulse signal Since the parameters used for the control calculation, such as the normal range of the pulse width and pulse interval, can be easily changed, the versatility of the system is excellent.

(Embodiment 5) Embodiment 5 of the present invention will be described below. This embodiment relates to claim 3 as in the fourth embodiment.

In the present embodiment, the control by the switching operation control means 11 is all digital control performed by a digital signal processor. Since the series of arithmetic processing is realized by the program of the digital signal processor, the effects described in the fourth embodiment can also be obtained in the present embodiment. Further, the digital signal processor has a built-in multiplier, and the product-sum operation is processed very quickly, so that the operation processing time can be hardly restricted.

Embodiment 6 Hereinafter, Embodiment 6 of the present invention will be described. This embodiment relates to claim 4.

In the present embodiment, the system configuration is the same as that of the first embodiment, and the switching operation control means 11 is all digitally controlled by a digital signal processor, and the pulse signal output from the voltage polarity detection means 20 is controlled. The pulse width and the pulse interval are measured by counting the number of times of switching of the switching elements 4a and 4b.

FIG. 9 is a waveform diagram showing the operation of the digital signal processor in this embodiment, and FIG. 10 is a flowchart showing the operation of this embodiment. As shown in FIG. 9, a digital signal processor having a function of outputting a PWM output signal in synchronization with an up / down counter was used. At this time, the duty of the PWM output signal is determined by the setting of the carrier frequency and the compare value of the PWM output signal based on the period value of the up / down counter. When the up / down counter matches the period value, A for detecting the input current flowing in the AC / DC converter and the DC voltage output from the AC / DC converter is used.
D conversion is performed, and an interrupt is generated when the A / D conversion is completed. In this interrupt, a series of control calculations shown in FIG. 10 are performed, and finally the compare value of the up / down counter is sequentially updated to control the switching operation while changing the duty of the PWM output signal.

The pulse signal output from the voltage polarity detecting means 20 is input to a general-purpose input terminal of the digital signal processor, and the level change is monitored. The number of times of switching of the switching element is counted.
As shown in FIG. 11, under the conditions that the carrier frequency of the PWM output signal is 20 KHz, the AC power supply frequency is 50 Hz, and the level of the pulse signal changes at the zero-cross timing of the AC power supply voltage of the AC power supply 1, The number of switching times is 200 times for the pulse width and 400 times for the pulse interval. If the number of switching operations during the pulse width period does not fall within the range of 180 to 220 and the number of switching operations during the pulse interval period does not fall within the range of 360 to 440, the switching operation is stopped.
The same control content as described above can be implemented.

As described above, according to the present embodiment, the pulse width and pulse interval time of the pulse signal can be measured without using the timer function of the digital signal processor.
Only the up / down counter having the M output function can be controlled.

Embodiment 7 Hereinafter, Embodiment 7 of the present invention will be described. This embodiment relates to claim 5.

FIG. 12 is a block diagram showing the configuration of this embodiment. The same components as those in the first to sixth embodiments are denoted by the same reference numerals.

In FIG. 12, the load 7 includes a DC / AC conversion circuit 24 for converting a DC voltage output from an AC / DC conversion circuit into an AC voltage, and a motor 25 connected to the DC / AC conversion circuit 24. In addition, an inverter device is constituted by the power supply device of the present invention described in the sixth embodiment and the DC / AC conversion circuit 24, and the motor 25
Is driven.

As a result, the motor can be driven by a highly reliable inverter device that does not allow an excessive current to flow through the AC / DC conversion circuit.

Embodiment 8 Hereinafter, Embodiment 8 of the present invention will be described. This embodiment relates to claim 6.

In this embodiment, the inverter device of the present invention described in the seventh embodiment is mounted on an air conditioner to drive an electric motor for a compressor.

According to the present invention, it is possible to realize a highly reliable air conditioner in which an excessive current does not flow in the AC / DC conversion circuit in the inverter device.

[0077]

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
A voltage polarity detection unit that outputs a pulse signal based on a voltage polarity in synchronization with a cycle of the AC power supply, a DC voltage detection unit that detects a DC voltage output by the AC / DC conversion circuit, and the pulse signal and the input. The power factor is improved while calculating the target current effective value and the target instantaneous value of the input current to be passed to the AC / DC conversion circuit from the current and the DC voltage, and the DC voltage is a predetermined target value. Switching operation control means for controlling the operation of the switching element so as to be a DC voltage, wherein the switching operation control means performs the switching operation unless the pulse width or pulse interval of the pulse signal falls within a predetermined range. By using a power supply device that controls to stop, the voltage polarity detection unit outputs an output when the AC power supply voltage is abnormal or the like. Even if the pulse signal is no longer normal state, an effect called it can perform stable power supply without excessive current flow.

According to a second aspect of the present invention, the switching operation control means includes a zero cross timing calculation means for calculating a zero cross timing of the AC power supply voltage from the pulse width and the pulse interval of the pulse signal output from the voltage polarity detection means. The power supply device according to claim 1, wherein the power supply device controls the restart of the switching operation after the pulse width or the pulse interval falls within a predetermined range at the zero-cross timing. In addition to the effect that it becomes possible to prevent an excessive current from occurring, there is also an effect that a steep rush current does not flow even when the switching operation is restarted.

According to a third aspect of the present invention, there is provided a power supply device according to any one of the first and second aspects, wherein either a microcomputer or a digital signal processor is used for the switching operation control means.
In addition to the effects of the power supply device of the present invention according to any one of claims 1 and 2, the number of parts can be reduced as compared with the case where the power supply device is configured by a combination of electronic circuits, and the system can be extremely easily systemized. Also has the effect of being superior in versatility.

According to a fourth aspect of the present invention, the switching operation control means measures the pulse width and the pulse interval of the pulse signal output from the voltage polarity detecting means by measuring the pulse width period and the pulse interval period, respectively. The power supply apparatus according to claim 3, wherein the switching is performed by counting the number of times of switching of the switching element performed at the same time, the pulse width and the pulse interval of the pulse signal are measured together with the effect of the present invention according to claim 3. Simplification of the program structure by not using the timer function to
This also has the effect of reducing the cost of a microcomputer or digital signal processor.

According to a fifth aspect of the present invention, there is provided a power supply according to any one of the first to fourth aspects, and a DC / AC converter for converting a DC voltage output from the power supply into an AC voltage. The effect of improving the reliability of the inverter device is obtained by using the inverter device having the above.

According to a sixth aspect of the present invention, there is provided an air conditioner configured to drive an electric motor for a compressor using the inverter device according to the fifth aspect of the present invention. This has the effect of improving the performance.

[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 AC power supply voltage and a pulse signal output from voltage polarity detection means in the embodiment.

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

FIG. 5 is a circuit diagram illustrating a voltage polarity detection unit according to a second embodiment of the present invention.

FIG. 6 is a waveform chart showing an AC power supply voltage and a pulse signal output from voltage polarity detection means in the embodiment.

FIG. 7 is a block diagram showing a configuration of a third embodiment of the present invention.

FIG. 8 is a waveform chart showing a pulse signal output from voltage polarity detection means in the embodiment.

FIG. 9 is a waveform chart showing a PWM output operation of the digital signal processor according to the sixth embodiment of the present invention.

FIG. 10 is a flowchart showing the operation of the embodiment.

FIG. 11 is a waveform chart showing the operation of the embodiment.

FIG. 12 is a block diagram showing a configuration of a seventh embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a conventional power supply device.

FIG. 14 is a block diagram showing another configuration of a conventional power supply device.

FIG. 15 is a circuit diagram showing a configuration of input voltage detecting means in the conventional example.

FIG. 16 is a waveform chart showing the operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 2a, 2b High-speed diode 3 Reactor 4, 4a, 4b Switching element 5, 9c Diode 5a, 5b Rectifier diode 6 Smoothing capacitor 7 Load 8 Current detecting means 9 Input voltage detecting means 9a Photocoupler 9b Resistance 10 DC voltage detection means 11 Switching operation control means 12 Low-pass filter 13 Target voltage calculation means 14 Voltage comparison means 15 Target current effective value calculation means 16 Target current instantaneous value calculation means 17 Current comparison means 18 PWM duty calculation means 19 PWM output determination means 20 Voltage polarity detecting means 21 Transformer 22 Diode bridge 23 Zero cross timing calculating means 24 DC / AC conversion circuit 25 Motor

Claims (6)

[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, voltage polarity detection means for outputting a pulse signal based on voltage polarity in synchronization with the cycle of the AC power supply, DC voltage detection means for detecting a DC voltage output by the AC / DC conversion circuit, and the pulse signal And calculating the target current effective value and the target current instantaneous value of the input current to be passed to the AC / DC conversion circuit from the input current and the DC voltage so as to improve the power factor, and Switching operation control means for controlling the operation of the switching element so as to attain a predetermined target DC voltage; A power supply device for controlling the switching operation to stop if a pulse width or a pulse interval of the pulse signal does not fall within a predetermined range. 2. The switching operation control means includes a zero-cross timing calculating means for calculating a zero-cross timing of an AC power supply voltage from a pulse width and a pulse interval of a pulse signal output from the voltage polarity detecting means. The power supply device according to claim 1, wherein control is performed such that restart of the switching operation after the pulse interval falls within a predetermined range is performed at the zero-cross timing. 3. 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. 4. The switching operation control means measures the pulse width and pulse interval of the pulse signal output from the voltage polarity detection means, and performs switching of the switching element during the pulse width period and the pulse interval period, respectively. 4. The power supply according to claim 3, wherein the power supply is performed by counting the number of times. 5. An inverter device comprising: the power supply device according to claim 1; and a DC / AC conversion circuit that converts a DC voltage output from the power supply device into an AC voltage. 6. An air conditioner configured to drive a motor for a compressor using the inverter device according to claim 5.