JP5549187B2 - DC power supply - Google Patents

Description

  The present invention relates to a DC power supply device that converts an AC voltage of an AC power supply into a DC voltage.

In a DC power supply device that converts an AC voltage from an AC power source into a DC voltage by short-circuiting / opening the AC power source through the reactor at least once in a half cycle of the AC power source, a reactor winding If the inductance value of the reactor is extremely low due to a short circuit of the wire, etc., the amount of heat generation increases due to an increase in the peak current value that flows through the switching element and an increase in the current ripple that flows through the reactor. It is necessary to prevent the switching element and the reactor from reaching an abnormal overheat state by adopting the switching element or by detecting an abnormality by some means.

  Conventionally, as a method for preventing abnormal overheating in the event of a short circuit in the reactor, as shown in FIG. 10, a signal output unit 101 that outputs a PAM drive signal for driving the switching means 106 and a current flowing through the switching means 106 are detected. When the instantaneous value of the detected current exceeds a predetermined reference value, the overcurrent detection unit outputs an overcurrent detection signal, and the overcurrent detection signal is output a predetermined number of times (for example, T = 3 s). (For example, X = 100 times), a short-circuit determination unit 104 that determines that the reactor 2 is short-circuited is provided. When the short-circuit determination unit 104 determines that the reactor 2 is in a short-circuit state, And a control device for a power supply circuit that suppresses an increase in input current flowing in a DC power supply device (converter) by correcting the input current value and limiting the input current value (for example, See Patent Document 1).

Japanese Patent Laid-Open No. 2007-300697

  However, the above-described conventional DC power supply device cannot detect that the reactor is in a short circuit state unless the switching operation for actually improving the power factor is started.

  Therefore, it is necessary to allow a situation where the peak value of the current flowing through the switching element temporarily becomes high, so that a sufficient margin is provided for the current value actually flowing when the reactor has a normal inductance value. It was necessary to use a switching element having a large rated current.

  The present invention solves the above-described conventional problems, and with a simple configuration, after the power is turned on, the short circuit of the reactor is detected before the switching operation for power factor improvement is started, and a short circuit abnormality is detected. In such a case, it is possible to reliably prevent an overheating state without flowing an excessive current through the switching element even when the reactor is short-circuited by maintaining a state where the switching operation is not performed for the protection operation. Therefore, it is possible to realize the protective operation of the apparatus with an inexpensive configuration by adopting a switching element having a smaller rated current.

In order to solve the above-described conventional problems, the DC power supply device of the present invention is configured to short-circuit / open an AC power supply via a reactor by a switching means at least once in a half cycle of the AC power supply, and in direct-current power supply that converts the voltage into a DC voltage, and the voltage phase detecting means of the AC power source, and a current detecting means for detecting a current flowing through the reactor or switching means, for switching means of the power factor improvement from power until starting the switching operation of a shall be shorted operate the switching means for a predetermined period of time, short-circuit operation is carried out multiple times, with each passing times, higher absolute value of the instantaneous voltage of the AC power source are those performed by comprising voltage phase, the magnitude of the current flowing through the reactor or switching means during a short circuit operation is predetermined Is larger than the quasi-current value, it is not conducted a switching operation for the power factor correction. Alternatively, the short-circuit operation is performed a plurality of times, and the short-circuit period is lengthened every time the number of times is followed, and the magnitude of the current value flowing through the reactor or the switching means during the short-circuit operation is larger than a predetermined reference current value In this case, the switching operation for improving the power factor is not performed.

Furthermore, the DC power supply device of the present invention performs switching for a predetermined short-circuit period at a predetermined voltage phase of the AC power supply voltage every predetermined time interval even after the switching operation for power factor improvement is started. A short circuit operation of the means is performed, the current value of the reactor or the switching means at the time of the short circuit is detected, and when the detected current value is larger than the reference current value, the switching operation for power factor improvement is stopped. Is.

  Since the direct current power supply device of the present invention can stop the protection without flowing a large current through the switching means even when the reactor is short-circuited after the power is turned on and before the switching operation is started, Since it is possible to reduce the thermal stress applied to the switching means, it is possible to use a switching element with a smaller rated current, so that the device can be protected with an inexpensive configuration. It becomes.

The figure which shows the structure of the direct-current power supply device in Embodiment 1 of this invention. (A) (b) The figure which shows an example of a structure of the voltage phase detection means in the DC power supply device of this invention, and the voltage phase detection by this voltage phase detection means The figure which shows the input current waveform at the time of normal operation in Embodiment 1 of this invention (A) (b) It is a waveform of each part at the time of short circuit detection of the reactor in Embodiment 1 of this invention, Comprising: The figure which shows the case where a reactor is normal and the inductance value of a reactor is lower than a normal value The figure which shows the structure of the DC power supply device in Embodiment 2 of this invention. The figure which shows the input current waveform at the time of normal operation in Embodiment 2 of this invention (A) (b) It is a waveform of each part at the time of the short circuit detection of the reactor in Embodiment 2 of this invention, Comprising: The figure which shows the case where a reactor is normal and the inductance value of a reactor is lower than a regular value The figure which shows the structure of the DC power supply device in Embodiment 3 of this invention. The figure which shows the waveform of each part at the time of the short circuit detection of the reactor in Embodiment 3 of this invention The figure which shows the structure of the conventional DC power supply device

A first aspect of the present invention is a DC power supply device that converts an AC voltage from an AC power source into a DC voltage by short-circuiting / opening the AC power source through a reactor using a switching means at least once in a half cycle of the AC power source. The power supply includes a voltage phase detection means for the AC power supply and a current detection means for detecting the current flowing through the reactor or the switching means, and from when the power is turned on until the switching means starts a switching operation for power factor improvement. , a shall be shorted operate the switching means for a predetermined period of time, short-circuit operation is carried out multiple times, with each passing times, which the absolute value of the instantaneous voltage of the AC power supply is performed in becomes higher voltage phase The switching operation is performed when the magnitude of the current value detected by the current detection means during a short circuit operation exceeds a predetermined reference current value. It is the casting.

As a result, it is possible to detect a decrease in the inductance of the reactor before actually starting the switching operation. Therefore, it is possible to detect a short-circuit abnormality of the reactor without causing an excessive current to flow through the switching means. In particular, by performing multiple short-circuit operations, the voltage at which the absolute value of the instantaneous voltage of the AC power supply increases as the number of times increases, as well as reducing the risk of missing a short-circuit abnormality due to the occurrence of an instantaneous power failure during the short-circuit operation. By performing the short circuit operation in the phase, the smaller the reactor inductance, the smaller the number of times that an abnormality can be detected. Therefore, when the reactor short circuit is abnormal, the current flowing through the switching means is further reduced.

  When the current flowing through the switching means is detected by the current detecting means, it is not necessary to determine whether the current detected by the current detecting means is the current when the switching means is short-circuited (ON). It is possible to detect the short circuit of the reactor with a simpler configuration than when detecting the current flowing through the reactor.

According to a second aspect of the present invention, there is provided a direct current power supply apparatus for converting an alternating current voltage from an alternating current power source into a direct current voltage by short-circuiting / opening the alternating current power source through a reactor at least once in a half cycle of the alternating current power source. The power supply includes a voltage phase detection means for the AC power supply and a current detection means for detecting the current flowing through the reactor or the switching means, and from when the power is turned on until the switching means starts a switching operation for power factor improvement. The switching means is short-circuited only for a predetermined period, the short-circuiting operation is performed a plurality of times, and the short-circuiting period is lengthened every time the number of times is increased, and the current value detected by the current detection means during the short-circuiting operation When the magnitude of exceeds a predetermined reference current value, the switching operation is not performed.

As a result, it is possible to detect a decrease in the inductance of the reactor before actually starting the switching operation. Therefore, it is possible to detect a short-circuit abnormality of the reactor without causing an excessive current to flow through the switching means. In particular, by performing the short-circuit operation multiple times, the risk of overlooking the short-circuit abnormality due to the occurrence of instantaneous power failure during the short-circuit operation is reduced, and the short-circuit period in the short-circuit operation is increased each time the reactor is operated. This is realized by further reducing the current flowing through the switching means when the short circuit is abnormal.

According to a third aspect of the present invention, in the first or second aspect, the power factor is improved only when the current value detected by the current detection means exceeds a predetermined reference value at least twice . The switching operation is not performed, and the risk of erroneously determining a short circuit abnormality due to noise on the circuit is reduced.

According to a fourth invention, in the first to third inventions, the short-circuit operation is performed at least once in both positive and negative polarities of the AC power supply, so that the DC power supply device has an asymmetric circuit configuration, Even if there is an abnormality related to the symmetry of the circuit with respect to both the positive and negative polarities of the AC power supply, such as a defective one switching element in a DC power supply device composed of two switching elements, it is possible to detect a short-circuit abnormality in the reactor It is.

According to a fifth invention, in the first invention, the reference current value in the short-circuit operation is set to a large value every time the number of times is increased, so that the absolute value of the instantaneous voltage of the AC power source is reduced in phase. Thus, the current flowing through the switching means when the reactor is short-circuited abnormally can be further reduced.

According to a sixth aspect , in the second aspect , the reference current value in the short-circuit operation is set to a large value every time the number of times is increased, thereby detecting an abnormality in the inductance of the reactor in the short-circuit operation with a shorter short-circuit period. Therefore, the current flowing through the switching means when the reactor is short-circuited abnormally is further suppressed.

7th invention is equipped with the voltage detection means of alternating current power supply in 1st-3rd invention, and makes the said reference current value high value, so that the absolute value of the instantaneous voltage of alternating current power supply at the time of the said short circuit operation becomes high. Thus, the detection accuracy of the inductance value of the reactor is improved by reducing the influence of variation due to the AC voltage.

According to an eighth invention, in the first to third inventions, the short-circuit period in at least the first short-circuit operation is set to a time equal to or shorter than the short-circuit withstand capability of the switching elements constituting the switching means, so that the reactor dead Even in the case of a short circuit, the switching means is surely prevented from being destroyed without requiring an overcurrent protection circuit capable of high-speed operation.

According to a ninth invention, in the first to third inventions, the voltage phase detection means is configured using a photocoupler, thereby realizing an inexpensive configuration.

According to a tenth aspect , in the first to third aspects, the reference current value is set lower than a maximum current value that flows through the switching unit during normal operation, thereby flowing through the switching unit when a short circuit of the reactor is detected. By suppressing the current below the normal operating range, the switching means is realized with an element having the minimum necessary rated current.

In an eleventh aspect based on the first to third aspects, the current detection during the short-circuit operation is performed by one AD conversion within the short-circuit period, thereby suppressing the burden on the AD conversion and control means. Therefore, it can be realized with an inexpensive and simple configuration.

  In addition, in a DC power supply device that performs input current control by PWM control during normal operation, the effect of facilitating easy synchronization of timing is achieved by performing short-circuit operation and AD conversion in synchronization with the carrier cycle of PWM control. Also play.

In a twelfth aspect according to any one of the first to third aspects, the short-circuit operation in which the absolute value of the instantaneous voltage and the short-circuit period of the AC power supply for starting the short-circuit operation are the same is included in the entire short-circuit operation. Because it is not necessary to increase the voltage phase of the AC power supply that starts the short-circuit or lengthen the short-circuit period just by overlooking the reactor short-circuit abnormality due to an instantaneous power failure or noise, switching means in the event of a reactor short-circuit abnormality The value of the current flowing through can be kept low.

In a thirteenth aspect of the present invention, in the first to third aspects of the present invention, after the short-circuit operation ends, after the switching operation for power factor improvement is started, the predetermined alternating current is at least once within a predetermined period. The switching means is short-circuited for a predetermined period at the voltage phase of the power supply or the voltage phase that is the absolute value of the predetermined instantaneous voltage of the AC power supply, and the magnitude of the current value detected by the current detection means during the short-circuit operation is By stopping the switching operation for power factor improvement when a predetermined reference current value is exceeded, a decrease in the inductance of the reactor is detected even during normal operation, and the switching operation is immediately protected and stopped. It is.

According to a fourteenth aspect , in the thirteenth aspect , the short-circuit operation is performed near the zero cross point of the AC power supply, thereby further reducing the influence on the distortion and power factor of the input current waveform during normal operation. is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a DC power supply device according to the first embodiment of the present invention.

As shown in FIG. 1, the direct-current power supply in the present embodiment includes a reactor 2 connected to one end of an alternating-current power supply 1, current detection means 3 that detects a current flowing through the reactor 2, and an alternating current via the reactor 2. Bidirectional switching means 4 for short-circuiting / opening the power source 1, a rectifier circuit 5 having one AC input terminal connected to a connection portion between the switching means 4 and the reactor 2, and a DC output terminal of the rectifier circuit 5 and A smoothing capacitor 6 and capacitors 7a and 7b respectively connected between the other input terminal and each DC output terminal are provided to form a voltage doubler rectifier circuit and supply a DC voltage to the load 8.

  Furthermore, the DC power supply device of the present embodiment includes voltage phase detection means 9 that is connected to both ends of the AC power supply 1 and detects the voltage phase of the AC power supply 1, and the input current from the AC power supply 1 is approximately sine. On / off control of the bidirectional switching means 4 composed of a combination of a diode bridge and one IGBT or two power MOSFETs connected in opposite directions so as to form a wavy current waveform It has the control means 10 which performs.

  FIG. 2 is a diagram showing an example of the configuration of the voltage phase detection means 9.

  The voltage phase detection means 9 can be configured by using a voltage detection transformer (PT), but as shown in FIG. 2A, it is configured by a circuit configured by a photocoupler and a resistor, By detecting the zero cross point of the AC power source 1 as shown in FIG. 2B and estimating the voltage phase of the AC power source 1 from the detected zero cross point, an inexpensive configuration can be achieved.

  FIG. 3 is a diagram showing an input current waveform during normal operation in the DC power supply device of the present embodiment.

  As shown in FIG. 3, the control means 10 of the DC power supply device of the embodiment performs on / off control of the switching means 4 based on PWM control using a carrier frequency of about 20 kHz corresponding to a non-audible range, The current waveform is shaped into a substantially sinusoidal shape to boost the voltage and improve the power factor.

  The DC power supply device according to the present embodiment detects a short-circuit of the reactor 2 after power-on and before starting a switching operation by PWM control performed for power factor improvement, and an inductance value is lower than a normal value. When it is determined that the value is a value, the protection operation state is set and the subsequent switching operation is not performed.

  In the present embodiment, the current detection means 3 is connected in series with the reactor 2, but the current detection means 3 only needs to be able to detect the current flowing through the reactor 2, so that it is in series with the reactor 2 as shown in FIG. Instead of being connected to, the AC line on the opposite side of the side to which the reactor 2 is connected may be connected.

  Hereinafter, the detailed content regarding the short circuit detection of the reactor 2 is described.

  4 (a) and 4 (b) are diagrams showing waveforms of respective parts when a short circuit is detected in the reactor 2 of the DC power supply device according to the present embodiment.

  FIG. 4A shows the AC voltage of the AC power source 1 and the current of the reactor 2 and the short circuit signal from the control unit when the reactor is normal.

  As shown in FIG. 4A, the control means 10 has a predetermined voltage phase (for example, θ = 10 °, 190 °) of the AC power source 1 that performs a short-circuit operation, which is stored in advance in the storage unit 10c (A1 in the drawing). , A2), the drive signal generator 10a generates a drive signal for forcibly short-circuiting the switching means 4 for a short-circuit period (for example, 5 μs) stored in advance in the storage unit 10c, and the switching means 4 is forcibly short-circuited. The current flowing through the reactor 2 during the short-circuit operation is detected by the current detection means 3.

  The control means 10 compares the magnitude of the detected current value with the reference current value stored in advance in the storage unit 10c in the reactor short-circuit detecting unit 10b, and if the detected current value exceeds the reference current value, By judging that the inductance of the reactor 2 is in an abnormal state lower than the normal value, and for the protection operation, the switching means 4 is kept in the OFF state and the switching operation for power factor improvement is not performed thereafter. The large current is prevented from flowing through the switching means 4.

  The reference current value is a current value determined by the product of a slope dI / dt of current increase obtained by dividing the magnitude of the AC voltage of the AC power source 1 by the normal inductance value of the reactor 2 and the forced short circuit time. Thus, it is set in consideration of fluctuations in the power supply voltage of the AC power supply 1 and variations in current detection. An abnormality in the inductance value of the reactor 2 can be reliably detected when the reference current value is generally about ½ or less of the normal inductance value of the reactor 2.

  Current detection is performed by a current sensor such as a CT and an AD converter in the microcomputer. However, the current detection method may be to detect the maximum value with a peak hold circuit or continuously. It is also possible to check the number and use the maximum value.

  Further, the short-circuit operation and AD conversion are performed in synchronization with the PWM control carrier cycle, and the AD conversion result of only the central detection value in the short-circuit period is used, and the reference current value is lower than the above (within the short-circuit period). Therefore, the short-circuit operation and the current detection timing can be synchronized with a simple configuration.

  Further, when the voltage phase detection means 9 using a photocoupler is used, in order to correctly estimate the voltage phase of the AC power supply 1, at least one cycle of the AC power supply 1 is required immediately after the power is turned on. The short-circuit detection of No. 2 is carried out after several cycles of the AC power source 1 have passed after the power is turned on and the voltage phase of the AC power source 1 can be reliably estimated.

  In the example of FIG. 4A, forcibly short-circuiting of the switching means 4 is performed once for each of the positive and negative polarities of the AC power source 1 in order to detect a short circuit of the reactor 2, but both of them reach the reference current value. Therefore, the reactor 2 is determined to be normal.

  As a result, although not shown, the control means 10 starts a switching operation for power factor improvement, and the switching operation is performed so as to obtain an input current waveform as shown in FIG. .

  Note that, as shown in FIG. 4A, by making a determination based on both positive and negative polarities of the AC power supply 1, in addition to detecting the short circuit of the reactor 2, the symmetry of the circuit can be confirmed.

  That is, when there is an abnormality in a part of the diode or the switching element constituting the switching means 4, the current detected at the time of the short circuit operation differs depending on the positive / negative polarity of the AC power supply 1, and thus the degree of imbalance is confirmed. Thus, it is possible to confirm the above abnormality before performing the switching operation.

  Moreover, it has the effect which suppresses also about the influence of a momentary power failure or noise by performing the current detection by short circuit operation | movement with the same short circuit period in multiple times.

  FIG. 4B is a waveform of each part when the inductance of the reactor 2 is lower than a normal value.

  In the example of FIG. 4B, since a current exceeding the reference current value stored in the storage unit 10c is detected twice at the time of a forced short circuit (B1 and B2 in the figure), the reactor 2 is determined to be a short circuit abnormality. Thereafter, no switching operation is performed.

  As shown in FIG. 4, by performing a short-circuit operation multiple times, even if an instantaneous power failure occurs in the event of a forced short-circuit, the risk of missing a short-circuit abnormality in the reactor without detecting current can be reduced. it can.

  Furthermore, although not shown in the figure, among the short-circuit operations having the same short-circuit period, when the reference current value is exceeded only during some short-circuit operations, there is a possibility that the current detection is affected by noise. As a result, it is determined that the reactor 2 is short-circuited abnormally only when the reference current value is exceeded by a predetermined number of times of at least 2 or more, and the switching operation is stopped due to noise due to noise. It is possible to reduce the risk of false detection.

  The reference current value for abnormality determination is set to be smaller than the maximum current value that flows through the switching means 4 during normal operation, and the short-circuiting time is set to the switching means 4 when the inductance value of the reactor 2 is in the normal range. The magnitude of the flowing current value is set to a short value that does not reach the reference current value.

  As a result, the power factor correction operation by the subsequent switching operation is not performed, and the protection operation state is established, so that an excessive current can be prevented from flowing through the switching means 4 even when the inductance of the reactor 2 is low. can do.

  Further, the short-circuit period is set to a time equal to or shorter than the short-circuit tolerance (acceptable short-circuit time) of the switching elements constituting the switching means 4.

  In general, when the reactor 2 is close to a dead short, the slope dI / dt of the increase in current flowing through the switching means 4 becomes very high, so that the switching elements constituting the switching means 4 can be safely protected without being destroyed. Requires an overcurrent protection circuit with a high response speed while controlling so as not to increase dI / dt at the time of OFF.

  However, in the DC power supply device of the present embodiment, since the short-circuit period is set to a time shorter than the short-circuit tolerance of the switching element, there is no risk of the element being destroyed. However, overcurrent protection with a fast response speed is not required to protect the switching means 4.

  As described above, the DC power supply apparatus according to the present embodiment forcibly short-circuits the AC power supply 1 through the reactor 2 for a short time before performing the switching operation for power factor improvement, and is larger than the reference current value. When a current value flows, the protection operation state is entered, and the switching operation for power factor improvement is not performed, so that an excessive current flows in the switching means 4 even when the reactor 2 is abnormal such as a short circuit. Therefore, the switching means 4 can be constituted by a switching element having a smaller rated current.

  Although not shown, in the DC power supply device of the present embodiment, after starting the switching operation of the switching means 4 for power factor improvement, similarly, at a predetermined voltage phase of the AC power supply 1, By performing a forced short-circuit operation and comparing the reference current value with a short-circuit detection, it is possible to detect an abnormality in the inductance value of the reactor 2 even during operation.

That is, when the inductance value of the reactor 2 is reduced during operation by performing the detection control at least once within a predetermined period in a range of about a few tens of seconds from the half cycle of the AC power supply 1. However, it is possible to quickly stop the protection of the apparatus without continuing the abnormal state with many current ripples over the above time interval.

  Further, it is clear from the current waveforms in FIGS. 3 and 4 that the forced short circuit operation is performed in the vicinity of the zero cross of the AC power supply 1 so that the effects of input current distortion and power factor reduction can be almost ignored. Since the operation can be continued while detecting the short circuit of the reactor, the apparatus can be protected and stopped promptly and safely even when the inductance of the reactor is reduced during the operation.

(Embodiment 2)
FIG. 5 is a diagram showing a configuration of a DC power supply device according to the second embodiment of the present invention.

  As shown in FIG. 5, the DC power supply in the present embodiment includes a reactor 2 connected to one end of an AC power supply 1 and bidirectional switching means 4 that short-circuits / opens the AC power supply 1 via the reactor 2. A current detecting means 3 for detecting a current flowing through the switching means 4, a rectifier circuit 5 having one AC input terminal connected to a connection portion between the switching means 4 and the reactor 2, and a DC output terminal of the rectifier circuit 5 And a smoothing capacitor 6 connected to, and supplies a DC voltage to the load 8.

  Furthermore, the DC power supply device according to the present embodiment includes voltage phase detection means 9 that is connected to both ends of the AC power supply 1 and detects the voltage phase of the AC power supply 1, and includes two pieces connected in opposite directions. It has a control means 10 for performing on / off control of the bidirectional switching means 4 composed of an IGBT or the like.

  FIG. 6 shows an example of an input current waveform during normal operation of the DC power supply device according to the present embodiment.

  As shown in FIG. 6, the control means 10 of the DC power supply device in the present embodiment shorts and opens the switching means 4 once or several times in a half cycle of the AC power supply 1 to Converts voltage to DC voltage and improves power factor.

  FIGS. 7A and 7B are waveforms of respective parts when a short circuit of the reactor is detected in the DC power supply device of the present embodiment.

  FIG. 7 (a) shows the waveform of each part when the reactor is normal.

  As shown in FIG. 7A, the control means 10 of the DC power supply device in the present embodiment is stored in advance in the storage unit 10c after the voltage phase of the AC power supply 1 can be detected after the power is turned on. In the voltage phase of the AC power source 1, the switching means 4 is forcibly short-circuited for a short period stored in advance in the storage unit 10 c.

  Further, the current value flowing through the switching means 4 at the time of the forced short circuit is detected, and when the detected current value is higher than the reference current value stored in the storage unit 10c, the protection operation state is set, and thereafter the switching operation is performed. Do not do.

  In the configuration of the first embodiment, the input current is supplied to the load 8 in the voltage phase when the instantaneous voltage of the AC power supply 1 is higher than the DC voltage of the smoothing capacitor 6 even when the switching means 4 is in the OFF state. Therefore, even when the switching means 4 is off, the current detection means 3 has a period during which current flows. However, in the configuration of the present embodiment, only when the switching means 4 is on, as shown in FIG. No current flows through the current detection means 3.

  Therefore, in the DC power supply device in the first embodiment, when the reference current value for abnormality determination cannot be set sufficiently higher than the input current value normally assumed at the time of short circuit detection, for example, the voltage of the power supply voltage 1 Based on the phase information and the on / off information of the switching means 4 in the control means 10, it is necessary to confirm whether or not the current detected by the current detection means 3 is that when the switching means 4 is short-circuited (ON). However, in the DC power supply device according to the present embodiment, it is not necessary to determine whether or not the current detected by the current detection unit 3 is a current when the switching unit 4 is short-circuited (ON).

  That is, in the present embodiment, the forced short circuit can be performed at an arbitrary voltage phase, so that the degree of freedom in design is increased and the short circuit of the reactor 2 can be detected with a simpler configuration.

  In FIG. 7A, the two forced short-circuit operations (A1 and A2 in the figure) are performed at a voltage phase in which the absolute value of the instantaneous voltage of AC voltage 1 is equal, but from the first time. However, the current value is gradually increased by extending the second short-circuit period.

  However, since the current flowing through the switching means 4 is sufficiently small at any time point, the reactor 2 is determined to be normal and is not shown, but thereafter, a switching operation for power factor improvement is started. The operation is continued with the input current waveform shown in FIG.

  FIG. 7B is a waveform of each part when the inductance value of the reactor is lower than a normal value.

  The two forced short-circuit operations (B1 and B2 in the figure) are performed at a voltage phase where the absolute value of the instantaneous voltage of the AC voltage 1 is equal, but the second short-circuit period is longer than the first. Since the current value gradually increased and exceeded the reference current value at the second time, it was determined that the inductance value of the reactor 2 was low, and although not shown in the figure, after this, the transition to the switching operation was not performed. Stop protection.

  Also, since the first short-circuit period of the two forced short-circuit operations is set to be equal to or shorter than the short-circuit withstand capability of the switching means 4, the switching means 4 can be destroyed even if the reactor 2 is in a dead short state. Absent.

  Furthermore, the ratio between the second short-circuit period and the first short-circuit period is, for example, equal to or less than the ratio of the maximum current value Ipmax of the peak current that can be passed through the switching means 4 and the magnitude of the current value detected by the current detection means 3. Since the magnitude of the current flowing through the switching means 4 can be suppressed to Ipmax or less by setting the value, the second short-circuit period can be set to a time longer than the short-circuit tolerance of the switching means 4. is there.

  As described above, the direct-current power supply device according to the present embodiment has a short-circuiting period that becomes shorter as the reactor 2 becomes almost short-circuited by gradually increasing the short-circuiting period when performing a plurality of forced short-circuiting operations. Can detect an abnormality in the inductance of the reactor, so that a protective operation can be performed without passing an excessive current through the switching means 4, and as a result, a switching element with a smaller rated current can be used for the switching means 4. Become.

  Also in the DC power supply device of the present embodiment, as in the first embodiment, after the switching operation of the switching means 4 for power factor improvement is started, the predetermined AC power supply 1 is set at predetermined time intervals. In this voltage phase, a forced short-circuit operation is performed and short-circuit detection is performed in comparison with the reference current value, so that it is possible to detect abnormality in the inductance value of the reactor 2 continuously during operation.

(Embodiment 3)
FIG. 8 is a diagram showing a configuration of a DC power supply device according to Embodiment 3 of the present invention.

  As shown in FIG. 8, the DC power supply device according to the present embodiment includes a rectifier circuit 5 connected in series to the AC power supply 1, a reactor 2 connected to a DC output terminal on the positive electrode side of the rectifier circuit 5, 2 is connected between the other end of the rectifier circuit 2 and the DC output terminal on the negative side of the rectifier circuit 5 to short-circuit / open the AC power supply 1 via the reactor 2 and a current for detecting a current flowing through the switching means 4 A detection means 3; an AC voltage detection means 13 connected between the DC output terminals of the rectifier circuit 5 to detect an instantaneous voltage of the AC power supply 1; a diode 12 having an anode connected to the other end of the reactor 2; A smoothing capacitor 6 connected between the cathode of 12 and the DC output terminal on the negative side of the rectifier circuit 5 is provided to supply a DC voltage to the load 8.

  FIG. 9 is a waveform of each part at the time of short circuit detection of the reactor 2 in the DC power supply device of the present embodiment.

  As shown in FIG. 9, the control means 10 of the DC power supply apparatus according to the present embodiment is stored in the storage unit 10c in advance after the power is turned on and before performing the switching operation of the switching means 4 for power factor improvement. In the voltage phase of the plurality of AC power supplies 1, the switching means 4 is forcibly short-circuited for each predetermined period stored in the storage unit 10 c in advance, and the current flowing through the switching means 4 is detected by the current detection means 3. 2 state is detected.

  FIG. 9 shows an example in which the inductance value of the reactor 2 is lower than the normal value. Since a current value exceeding the reference current value is detected at the third forced short circuit (A3 in the figure), the forced short circuit operation is terminated. It shows a state in which the switching operation for power factor improvement is not started in the protection operation state.

  The reference current value is corrected according to the voltage of the AC power supply 1.

  For example, in a product with a rated AC voltage of 100V, when an AC voltage with an effective value equivalent to 110V is detected, a value obtained by multiplying the reference current value stored in the storage unit 10c by 1.1 is defined as a corrected reference current value. As described above, the voltage is adjusted in proportion to the power supply voltage of the AC power supply 1.

  By performing the above control, it is possible to cancel the influence due to the voltage variation of the AC power supply 1 at the time of current detection when the reactor 2 is forcibly short-circuited, so that the short-circuit detection accuracy of the reactor 2 can be improved.

  In the present embodiment, the reference current value is constant regardless of the AC voltage phase at the time of the short circuit, but the reference current value in the voltage phase where the absolute value of the instantaneous voltage of the AC power supply 1 is low is set to a lower value. By setting a higher reference current value in a voltage phase where the absolute value of the instantaneous voltage is higher, an abnormality in the inductance of the reactor 2 can be detected in a voltage phase where the absolute value of the instantaneous voltage of the AC power supply 1 is lower. When the reactor 2 is short-circuited, the value of the current flowing through the switching means 4 can be further suppressed.

  As described above, in the DC power supply device according to the present embodiment, when the forced short-circuit operation of the switching means 4 is performed a plurality of times, the absolute value of the instantaneous voltage of the AC power supply 1 increases every time the number of times is increased. By performing the short-circuit operation, the device can be protected while further suppressing the current flowing through the switching means 4 when the inductance of the reactor 2 is abnormal.

Also in the DC power supply device of the present embodiment, as in the first and second embodiments, after the switching operation of the switching means 4 for power factor improvement is started, the AC power supply 1 is provided at predetermined time intervals. By performing a forced short-circuit operation at a predetermined voltage phase and performing short-circuit detection in comparison with the reference current value, it is possible to detect abnormality in the inductance value of the reactor 2 continuously during operation.

  As described above, the DC power supply device according to the present invention detects an abnormality in the inductance of the reactor such as a short circuit after the power is turned on before performing the switching operation, and with a simple configuration even after the switching operation is started. The protection means can be stopped without applying a load to the switching means, and can be applied to almost all electric appliances that are supplied with power by an AC power source such as an air conditioner, a refrigerator, and a washing machine.

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Reactor 3 Current detection means 4 Switching means 5 Rectifier circuit 6 Smoothing capacitor 7 Capacitor 8 Load 9 AC voltage phase detection means 10 Control part 10a Drive signal generation part 10b Reactor short-circuit detection part 10c Storage part

Claims (14)

At least once in a half cycle of the AC power supply, using a switching means, the AC power supply is short-circuited / opened through the reactor, and the AC power supply voltage is converted into a DC voltage from the AC power supply. Phase detection means and current detection means for detecting the current flowing through the reactor or switching means, and only during a predetermined short-circuit period from when the power is turned on until the switching operation for power factor improvement by the switching means is started a shall be shorted operate the switching means, the short operations are performed multiple times, with each passing times, which the absolute value of the instantaneous voltage of the AC power supply is performed in higher becomes the voltage phase, a short circuit operation if at the magnitude of the current value detected by said current detecting means exceeds a reference current value set in advance, the scan for the power factor correction DC power supply apparatus characterized by not perform etching operation. At least once in a half cycle of the AC power supply, using a switching means, the AC power supply is short-circuited / opened through the reactor, and the AC power supply voltage is converted into a DC voltage from the AC power supply. Phase detection means and current detection means for detecting the current flowing through the reactor or switching means, and only during a predetermined short-circuit period from when the power is turned on until the switching operation for power factor improvement by the switching means is started The switching means is short-circuited. The short-circuiting operation is performed a plurality of times, and the short-circuiting period is lengthened every time the number of times is increased, and the current value detected by the current detection means during the short-circuiting operation is large. When the power exceeds a predetermined reference current value, the switching operation for power factor improvement is not performed. DC power supply. In the short-circuit operation, the switching operation for power factor improvement is not performed when the current value detected by the current detection means exceeds a predetermined reference current value at least twice or more. The DC power supply device according to claim 1 or 2. The DC power supply device according to any one of claims 1 to 3, wherein the short-circuit operation is performed at least once in both positive and negative polarities of the AC power supply. 2. The DC power supply device according to claim 1 , wherein the reference current value is set to a large value every time the number of times is increased. 3. The DC power supply device according to claim 2 , wherein the reference current value is set to a large value every time the number of times is increased. Comprising a voltage detecting means of the AC power supply, as the absolute value increases the instantaneous voltage of the AC power supply at the time of the short operation, any one of claims 1 to 3, characterized in that a high value of the reference current value The direct current power supply device described in 1. The DC power supply device according to any one of claims 1 to 3, wherein the short-circuit period in at least the first short-circuit operation is set to a time equal to or shorter than a short-circuit tolerance of a switching element constituting the switching means. . The DC power supply device according to any one of claims 1 to 3, wherein the voltage phase detection means is configured using a photocoupler. The DC power supply device according to any one of claims 1 to 3, wherein the reference current value is set lower than a maximum current value flowing through the switching means during normal operation. 4. The DC power supply device according to claim 1, wherein the current detection during the short-circuit operation is performed by one AD conversion within a short-circuit period. 4. The short circuit operation according to claim 1, wherein the short circuit operation includes a short circuit operation in which the absolute value of the instantaneous voltage and the short circuit period of the AC power supply for starting the short circuit operation are the same . The direct-current power supply device according to item 1 . After the short-circuit operation is completed, after the switching operation for improving the power factor is started, at least once in a predetermined period, the voltage phase of the predetermined AC power supply or the absolute voltage of the predetermined AC power supply instantaneous voltage is absolute. when the value a becomes the voltage is short-circuited operate the switching means for a predetermined short time period by the phase, magnitude of the current value detected exceeds the reference current value set in advance by the current detecting means during a short circuit operation, the force The DC power supply device according to any one of claims 1 to 3, wherein a switching operation for rate improvement is stopped. The DC power supply device according to claim 13 , wherein the short-circuit operation is performed near a zero cross point of an AC power supply.