JPWO2013157387A1 - Rectifier and rectifier system - Google Patents

Abstract

Provided are a rectifying device and a rectifying system that enable harmonic switching that quickly responds even when the value of the input current greatly fluctuates, and that can provide sufficient effects as power factor improvement and harmonic suppression. Select the switching pattern data corresponding to the value of the input current, turn on and off each MOSFET based on the selected switching pattern data, and then sequentially correct the selected switching pattern data in the direction of improving the power factor. On the other hand, each MOSFET is turned on and off based on the corrected switching pattern data, and the difference between the switching pattern data for each correction and the selected switching pattern data is obtained. If the obtained difference is less than the set value, The correction is continued, and if the obtained difference is equal to or larger than the set value, the initial selection is returned.

Description

  Embodiments described herein relate generally to a rectifier and a rectifier system that convert an AC voltage into a DC voltage.

  A rectifier circuit that rectifies the voltage of a three-phase AC power source and converts it into a DC voltage has three series circuits in which a pair of diodes are connected in series, and the interconnection point of each diode in these series circuits is a three-phase AC Connected to each phase of the power supply. A smoothing capacitor is connected to the output terminal of the rectifier circuit, and a load is connected to the smoothing capacitor.

  The three-phase AC power supply voltage is composed of three phase voltages whose phases are different from each other by 120 °. With these phase voltages, a current flows through the positive diode of each series circuit to the smoothing capacitor, and from the smoothing capacitor to each series circuit. Current flows through each negative diode.

  In addition, in order to improve the power factor in such a rectifier circuit and to suppress the harmonic current contained in the input current, a reactor is provided on the input side and a plurality of switches for forming a short circuit for these reactors are connected. Then, a three-phase harmonic reduction circuit is adopted that switches the switches at an appropriate timing to cause the input current waveform to follow a sine wave (for example, described in JP 2010-233292 A).

In the above switching, for example, a switching pattern corresponding to the value of the input current is first selected, the switch is turned on / off based on the selected switching pattern, and then the selected switching pattern is sequentially increased in a direction in which the power factor improves. While correcting, the switch is turned on / off based on the corrected switching pattern.
However, when the value of the input current largely fluctuates, the correction of the switching pattern cannot catch up with the fluctuation, and a sufficient effect as power factor improvement and harmonic suppression may not be obtained.

  An object of an embodiment of the present invention is to enable switching corresponding to a rapid change even when the value of an input current greatly fluctuates, and thereby a rectifier and a rectifier that can obtain sufficient effects as power factor improvement and harmonic suppression Is to provide a system.

  A rectifier according to an embodiment of the present invention includes a rectifier circuit that rectifies the voltage of an AC power supply, a reactor provided between the connection of the AC power supply and the rectifier circuit, and a short circuit to the AC power supply through the reactor and the rectifier circuit. A switching element for forming a path, a detecting means for detecting an input current from the AC power supply, a detecting means for detecting a power factor, and a control means are provided. The control means selects a switching pattern for intermittently turning on the switching element in a predetermined phase of the voltage of the AC power supply according to the detection current of the detection means, and the switching based on the selected switching pattern The device is turned on and off, and then the selected switching pattern is sequentially corrected in a direction in which the detection power factor of the detection means improves, and the switching device is turned on and off based on the switching pattern for each correction. Then, the difference between the switching pattern for each correction and the switching pattern at the time of selection is obtained. If the obtained difference is less than a predetermined value, the correction is continued, and if it is greater than the predetermined value, the selection is returned to the selection.

It is a block diagram which shows the structure of one Embodiment. It is a figure which shows the waveform of the input voltage in one Embodiment. It is a flowchart which shows control of one Embodiment. It is a block diagram which shows the structure of the modification of one Embodiment.

[1] A first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a plurality of, for example, three rectifiers (three-phase rectifiers) 10 are connected to the R, S, and T phases of a three-phase AC power source 1. The output terminals of these rectifiers 10 are commonly connected to the smoothing capacitor 70. The voltage generated in the smoothing capacitor 70 is supplied to the load 2. The load 2 is, for example, an inverter device for driving a motor. The rectifiers 10 are connected in parallel to each other and are connected to each other via a communication line. The number of rectifiers 10 corresponding to the capacity of the load 2 can be increased as appropriate. The rectifier 10 and the smoothing capacitor 70 constitute a rectifier system.

  The rectifier 10 includes a rectifier circuit (three-phase rectifier circuit) 20 connected to the three-phase AC power source 1, and reactors 11, 12, 13 provided in connection lines between the rectifier circuit 20 and the three-phase AC power source 1. The zero cross detection circuits 41, 42, 43 and current sensors 51, 52, 53 and the output voltage of the rectifier circuit 20 provided in the connection line between the reactors 11, 12, 13 and the three-phase AC power supply 1 are detected. It has a voltage detection circuit 47, a current detection circuit 48 that detects an output current of the rectifier circuit 20, a control unit 60, a memory (storage means) 61, and a communication unit 62.

  The rectifier circuit 20 includes an R-phase series circuit in which a positive diode 21 and a negative diode 22 are connected in series, an S-phase series circuit in which a positive diode 23 and a negative diode 24 are connected in series, and a positive diode 25 and a negative side. It has a T-phase series circuit in which diodes 26 are connected in series. An interconnection point between the positive side diode 21 and the negative side diode 22 is connected to the R phase of the three-phase AC power supply 1. An interconnection point between the positive side diode 23 and the negative side diode 24 is connected to the S phase of the three-phase AC power supply 1. An interconnection point between the positive side diode 25 and the negative side diode 26 is connected to the T phase of the three-phase AC power supply 1. That is, the rectifier circuit 20 converts the three-phase AC voltage of the three-phase AC power source 1 into a DC voltage and outputs the DC voltage from the positive output terminal (+) and the negative output terminal (−). Switching elements such as MOSFETs 31, 32, 33, 34, 35, and 36 are connected in parallel to the positive side diodes 21, 23, 25 and the negative side diode diodes 22, 24, 26 of the rectifier circuit 20, respectively.

  When MOSFETs are used as the switching elements, the MOSFETs 31, 32, 33, 34, 35, and 36 have parasitic diodes therein, so that these parasitic diodes are directly used as the positive side diodes 21, 23, 25 and the negative side. Used as diode diodes 22, 24, 26. When the switching element is not a MOSFET but a transistor or IGBT, it is necessary to prepare positive side diodes 21, 23, 25 and negative side diode diodes 22, 24, 26 separately from the switching element.

  The zero cross detection circuit 41 detects the zero cross point of the R-phase input voltage from the three-phase AC power supply 1. The zero cross detection circuit 42 detects the zero cross point of the S phase input voltage from the three-phase AC power supply 1. The zero cross detection circuit 43 detects the zero cross point of the T-phase input voltage from the three-phase AC power supply 1. The current sensor 51 detects the value of the R-phase input current from the three-phase AC power source 1. The current sensor 52 detects the value of the S-phase input current from the three-phase AC power supply 1. The current sensor 53 detects the value of the T-phase input current from the three-phase AC power supply 1.

  Note that three zero cross detection circuits 41, 42, 43 and three current sensors 51, 52, 53 are provided to accurately detect the zero cross point of each phase input voltage and the current value of each phase input current. One of the zero cross points of each phase input voltage can be detected from the phase shift of the input voltage of the two phases, and one of the values of each phase input current is calculated from the value of the input current of the two phases Since it can be obtained, two zero cross detection circuits and two current sensors may be provided. The number of parts and the cost can be reduced.

  The communication unit 62 performs mutual data communication with the communication unit 62 of the other rectifying device 10 via a communication line.

  The memory 61 stores a plurality of switching pattern data for on / off driving of the MOSFETs 31, 32, 33, 34, 35, and 36. These switching pattern data are for intermittently turning on each MOSFET on at least the leading edge side of the phase where each phase input voltage from the three-phase AC power supply 1 is at a positive level and at least the leading edge side of the phase where it is at a negative level. The ON timing and OFF timing are sequentially determined as the phase progresses. These switching pattern data are respectively associated with the value (effective value) of each phase input current from the three-phase AC power source 1. The leading edge side means the rising and falling portions of each phase input voltage from 0V, specifically, the range of 0 ° to 60 ° and the range of 180 ° to 240 ° of the waveform of each phase input voltage. Means.

  That is, as shown in FIG. 2, the leading edge side of the phase at which each phase input voltage is at the positive level is from the zero crossing point to the next zero crossing point of the R phase input voltage, S phase input voltage, and T phase input voltage. Among the half cycle periods of electrical angles 0 ° to 180 °, periods Rx1, Sx1, and Tx1 of the forward electrical angles 0 ° to 60 °. The leading edge side of the phase that is the negative level of each phase input voltage has an electrical angle of 180 ° to 360 ° from the zero cross point to the next zero cross point of the R phase input voltage, S phase input voltage, and T phase input voltage. Among the half cycle periods, the periods Ry1, Sy1, and Ty1 are forward electrical angles of 180 ° to 240 °. Note that intermittently turning on means repeating on and off at a predetermined time interval.

The control unit 60 has the following control means (1) to (4) as main functions.
(1) Of the switching pattern data in the memory 61, switching pattern data corresponding to the value (effective value) of each phase input current detected by the current sensors 51 to 53 is selected, and the selected switching pattern data Based on the switching pattern data after the correction, the MOSFETs 31 to 36 are turned on and off based on the corrected switching pattern data. In addition, the difference between each switching pattern for each correction and each switching pattern at the time of the selection is obtained. If the obtained difference is less than a predetermined value, the correction is continued. First control means for returning to the above selection if the value is greater than or equal to the value. Here, the difference between each switching pattern data for each correction and each switching pattern data at the time of selection is, for example, a difference in time width of on data at the same timing.

  (2) The detected currents (input currents) of the current sensors 51 to 53 in all the rectifiers 10 including the rectifier 10 are grasped by data communication of the communication unit 62, and any detected current is near zero (less than 2A, etc.) ) Or second control means for stopping on / off of the MOSFETs 31 to 36 when a predetermined value or more is reached.

  (3) The average value of the detected currents of the current sensors 51 to 53 in all the rectifying devices 10 obtained as described above is obtained, and the switching elements of the MOSFETs 31 to 36 are turned on so that the detected current in the rectifying device 10 approaches this average value. Third control means for adjusting an ON period at the time of OFF.

  (4) The detection current of the current detection circuit 48 (the output current of the rectification circuit 20) in all the rectification devices 10 including the rectification device 10 is grasped by data communication of the communication unit 62, and any detection current is determined in advance. Fourth control means for stopping on / off of the MOSFETs 31 to 36 of all the rectifiers 10 when the predetermined value or more is reached.

Next, the operation will be described.
In the phase where the R-phase input voltage is at a positive level, a current flows from the three-phase AC power source 1 through the reactor 11 and the positive diode 21 to the smoothing capacitor 70, and the current passing through the smoothing capacitor 70 first becomes the negative diode 24. And the reactor 12 returns to the S phase of the three-phase AC power supply 1, and then the path returning to the T phase of the three-phase AC power supply 1 through the negative diode 26 and the reactor 13 is formed as the phase of the R phase advances. Is done. In addition to this operation, the MOSFET 32 is intermittently turned on in a period Rx1 of 0 ° to 60 ° on the leading edge side of the phase where the R-phase input voltage is at a positive level. When the MOSFET 32 is turned on, the interconnection point of the diodes 21 and 22 is electrically connected to the negative output terminal of the rectifier circuit 20, and as shown by an arrow in FIG. 1, the reactor 11, the MOSFET 32, and the negative diode are connected to the three-phase AC power source 1. 24, a short circuit is formed through the reactor 12.

  In the phase where the S-phase input voltage is at a positive level, a current flows from the three-phase AC power source 1 through the reactor 12 and the positive diode 23 to the smoothing capacitor 70, and the current passing through the smoothing capacitor 70 first becomes the negative diode 26. And the reactor 13 returns to the T phase of the three-phase AC power source 1, and then the path returns to the R phase of the three-phase AC power source 1 through the negative diode 22 and the reactor 11 as the phase of the S phase advances. Is done. In addition to this operation, the MOSFET 34 is intermittently turned on during a period Sx1 of 0 ° to 60 ° on the leading edge side of the phase where the S-phase input voltage is at a positive level. When the MOSFET 34 is turned on, the interconnection point of the diodes 23 and 24 is electrically connected to the negative output terminal of the rectifier circuit 20, and the short-circuit path through the reactor 12, the MOSFET 34, the negative diode 26, and the reactor 13 with respect to the three-phase AC power supply 1. Is formed.

  In a phase in which the T-phase input voltage is at a positive level, a current flows from the three-phase AC power source 1 through the reactor 13 and the positive diode 25 to the smoothing capacitor 70, and the current passing through the smoothing capacitor 70 is firstly the negative diode 22. And the reactor 11 returns to the R phase of the three-phase AC power source 1, and then the path returns to the S phase of the three-phase AC power source 1 through the negative diode 24 and the reactor 12 as the phase of the T phase advances. Is done. In addition to this operation, the MOSFET 36 is intermittently turned on during the period Tx1 of 0 ° to 60 ° on the leading edge side of the phase where the T-phase input voltage is positive. When the MOSFET 36 is turned on, the interconnection point between the diodes 25 and 26 is electrically connected to the negative output terminal of the rectifier circuit 20, and the short-circuit path through the reactor 13, the MOSFET 36, the negative diode 22, and the reactor 11 with respect to the three-phase AC power supply 1. Is formed.

  In the leading edge side periods Ry1, Sy1, and Ty1 of the phase in which the R-phase input voltage, the S-phase input voltage, and the T-phase input voltage are negative, the MOSFETs 31, 33, and 35 connected in parallel with the positive diodes 21, 23, and 25 are intermittent. Turn on. About the operation | movement accompanying these intermittent ON of MOSFET, it becomes the same operation pattern as a positive level period fundamentally only by the opposite of positive / negative. Therefore, the detailed description is abbreviate | omitted.

  As described above, the MOSFETs 32, 34, and 36 of the rectifier circuit 20 are intermittently turned on in the leading edge periods Rx1, Sx1, and Tx1 of the phase in which the R-phase input voltage, the S-phase input voltage, and the T-phase input voltage are positive levels. The MOSFETs 31, 33, and 35 of the rectifier circuit 20 are intermittently turned on in the leading edge side periods Ry1, Sy1, and Ty1 of the phase in which the R-phase input voltage, the S-phase input voltage, and the T-phase input voltage become negative levels. The waveform of the input current to the device 10 can be approximated to a sine wave with good followability. Thereby, while a power factor improves, the harmonic current contained in the input current to the rectifier 10 can be suppressed. The period Rx1, Sx1, Tx1, Ry1, Sy1, Ty1 of the leading edge side where the MOSFET is intermittently turned on is affected by the on / off control of one phase on the current waveforms of the other two phases. It hits the rise of each phase in a short period. Therefore, by selecting this period, a large harmonic current reduction effect can be obtained with a small number of switching operations. In addition, the number of times of switching can be reduced and switching noise can be reduced as compared with the case of switching at a high frequency in all phases.

  On the other hand, as shown in the flowchart of FIG. 3, among the switching pattern data in the memory 61, the switching pattern data corresponding to the value (effective value) of each phase input current detected by the current sensors 51 to 53 is stored in the memory 61. (Step 101), and the MOSFETs 31 to 36 are turned on and off based on the selected switching pattern data (step 102). Originally, the switching pattern data corresponding to the effective value of the input current stored in the memory 61 is experimentally set assuming an operating state of a specific load. For this reason, during actual operation, the stored switching pattern data may not be an optimum value from the viewpoint of power factor improvement and harmonic reduction due to the influence of temperature, load fluctuation and the like. Therefore, even if the execution values are the same, it is possible to obtain harmonics and improve the power factor by shifting the switching pattern. In order to realize this, the switching pattern is corrected in step 103 and later described later.

  That is, each phase input voltage and each phase input current based on the zero cross point of each phase input voltage detected by the zero cross detection circuits 41 to 43 and the value of each phase input current detected by the current sensors 51 to 53. Is obtained, and the amount of deviation of the power factor cos θ is obtained by integrating the power factor cos θ based on the phase difference θ and the value of each phase input current (step 103). Then, the switching pattern data selected first is sequentially corrected in a direction in which the obtained deviation amount of the power factor cos θ is reduced, that is, in a direction in which the power factor is improved (step 104). The difference between the switching pattern data for each correction and the initially selected switching pattern data is obtained (step 105), and the difference is compared with the set value (step 106).

  If the obtained difference is less than the set value (NO in step 106), it is then determined whether or not the value (effective value) of each phase input current detected by the current sensors 51 to 53 has changed by more than the set value. (Step 107). If the detected current value (effective value) of the current sensors 51 to 53 has not changed more than the set value (NO in step 107), the process returns to step 102, and the MOSFETs 31 to 36 are turned on based on the corrected switching pattern data. Driven off. Subsequently, a deviation amount of the power factor cos θ is obtained (step 103), and the corrected switching pattern data is further corrected in a direction in which the deviation amount is reduced, that is, in a direction in which the power factor is improved (step 104). As described above, as long as the deviation amount of the power factor cos θ is within the predetermined range, the switching pattern data is corrected so that the switching pattern is optimally repeated. For example, a method such as a hill climbing method is used to correct the switching pattern. Specifically, switching is performed by shifting the switching pattern in the + or − direction by a predetermined phase. As a result, if the power factor shift amount decreases, the switching pattern is shifted again by the predetermined phase in the same direction. On the other hand, if the amount of power factor shift increases as a result of switching with a new switching pattern, the operation of shifting again by a predetermined phase in the reverse direction is repeated.

Further, if the value (effective value) of the detected current of the current sensors 51 to 53 has changed more than the set value during such a correction operation (YES in Step 107), the value of the detected current of the current sensors 51 to 53 is determined. Is selected from the memory 61 (step 101). After that, the switching pattern is corrected again. (Steps 103-106)
On the other hand, if the calculated difference is equal to or greater than the set value (YES in step 106), the situation of the surroundings and load fluctuates, and it is determined that the optimum value cannot be reached even after repeated corrections. In addition, the process returns to the first step 101 without using the corrected switching pattern data, and the switching pattern data (initial value) corresponding to the value of the current detected by the current sensors 51 to 53 is selected again. By selecting the switching pattern data anew, it becomes possible to reach the appropriate switching pattern more quickly than when the correction of the switching pattern data continues. Thereby, sufficient effects can be obtained as power factor improvement and harmonic suppression.

  In addition, since each rectifier 10 can be added or detached according to the capacity of the load 2, when the load 2 is an air conditioner having various models having different capacities, for example, the rectifier 10 is adapted to the model. Select the number of connections. As a result, it is not necessary to individually design a dedicated rectifier for each model, and the development cost, development period, and cost of the air conditioner can be reduced, and inventory management is facilitated.

  Further, the detected currents of the current sensors 51 to 53 in all the rectifying devices 10 including the rectifying device 10 are grasped by each rectifying device 10 through data communication of the communication unit 62, and any detected current is near zero or predetermined. When the abnormal value is equal to or greater than the value, the on / off of the MOSFETs 31 to 36 in each rectifier 10 is immediately stopped. Thereby, destruction of electric parts including MOSFET 31-36 of each rectifier 10 is prevented. Since each rectifier 10 has the same specification and performs data communication with each other, any one rectifier 10 may store a predetermined value for determining an abnormality.

  Furthermore, the average value of the detected currents of the current sensors 51 to 53 in all the rectifying devices 10 that have been grasped is obtained, and the detected currents of the individual current sensors 51 to 53 of each rectifying device 10 approach this average value. The on period when the MOSFETs 31 to 36 are turned on and off is adjusted. When the MOSFETs 31 to 36 in each rectifier 10 have on / off timing, on / off frequency, switching patterns, and the like, currents flow intensively to any of the rectifiers 10, and the MOSFETs 31 to 36 are caused by the current concentration. Although there is a possibility that electric parts such as 36 are consumed quickly, the current balance between the rectifiers 10 can be maintained by adjusting the ON period. Thereby, the malfunction that consumption of an electrical component is accelerated can be prevented.

  The detected currents of the current detection circuits 48 in all the rectifiers 10 are also grasped by the respective rectifiers 10 by data communication of the communication unit 62, and the detected currents of the current detection circuits 48 in any of the rectifiers 10 are for abnormality determination. When it becomes more than a predetermined value, ON / OFF of MOSFET31-36 of each rectifier 10 is stopped. For example, when the positive side MOSFET and the negative side MOSFET in the rectifier circuit 20 of any of the rectifiers 10 are erroneously fired simultaneously due to the influence of noise or the like, the positive side line and the negative side line of the rectifier circuit 20 are There is a possibility that a large short-circuit current (also referred to as overcurrent) flows through the short circuit and the MOSFETs 31 to 36 may be destroyed, but the MOSFETs 31 to 36 are destroyed by immediately stopping the on / off of the MOSFETs 31 to 36. A malfunction can be prevented. Moreover, since the MOSFETs 31 to 36 are turned on and off not only in the rectifier 10 in which the short circuit has occurred, but also in the remaining rectifiers 10, the MOSFETs 31 to 36 are destroyed by the short circuit current flowing into the other rectifiers 10. Can also be prevented.

[2] A second embodiment of the present invention will be described.
In the first embodiment, when the detected current of any of the current detection circuits 48 in each rectifier 10 becomes equal to or greater than a predetermined value, the MOSFETs 31 to 36 of each rectifier 10 are turned on and off. On the other hand, in the second embodiment, as shown in FIG. 4, a normally closed relay contact 49 is inserted into the positive output line of the rectifier circuit 20, and any of the current detection circuits 48 in each rectifier 10 is connected. When the detected current exceeds a predetermined value, the relay contact 49 is opened in addition to stopping the on / off of the MOSFETs 31 to 36 of each rectifier 10. By opening the relay contact 49 in addition to stopping the on / off of the MOSFETs 31 to 36, the short-circuit current does not flow into the other rectifiers 10, and the reliability of protection against the short-circuit current is improved.

  Other configurations, operations, and effects are the same as those in the first embodiment. Therefore, the description is omitted.

[3] A third embodiment of the present invention will be described.
In the first embodiment, each of the rectifiers 10 is executed including the abnormality determination of the other rectifiers 10. On the other hand, in the third embodiment, when a plurality of rectifiers 10 are connected by communication, one three-phase rectifier is set as a master unit, the other rectifier 10 is set as a slave unit, and set as a master unit. Only the connected rectifier 10 determines the abnormality of all the connected rectifiers 10 and instructs the operation / abnormal stop of all the rectifiers 10 by communication.

  Other configurations, operations, and effects are the same as those in the first embodiment. Therefore, the description is omitted.

[4] A fourth embodiment of the present invention will be described.
In the first embodiment, as the period in which the MOSFET is intermittently turned on, the period Rx1, Sx1, Tx1 of the leading edge side 0 ° to 60 ° of the phase in which the input voltage becomes positive level, and the phase in which the input voltage becomes negative level Periods Ry1, Sy1, and Ty1 of the leading edge side of 0 ° to 60 ° were set. In the fourth embodiment, in addition to this setting, a period of 120 ° to 180 ° of the trailing edge side of the phase in which the input voltage is at a positive level, and a period of 120 ° to 180 ° of the trailing edge side of the phase in which the input voltage is at a negative level. Set. In this case, 0 ° to (40 ° ± 10 °) is set as the period Rx1, Sx1, Tx1, Ry1, Sy1, Ty1 on the leading edge side, and (160 ° ± 10 °) to 180 ° is set as the period on the trailing edge side. May be. Here, the trailing edge side means a falling (negative level phase) and falling (positive level phase) portion of each AC voltage toward 0 V, specifically, 120 ° to 180 ° of each AC voltage waveform. The range of ° and the range of 300 ° to 360 ° are meant.

  For example, when the zero cross point of each phase input voltage is expressed as 0 ° regardless of whether it is positive or negative, when 0 ° to 30 ° is set as the period Rx1, Sx1, Tx1, Ry1, Sy1, Ty1 on the leading edge side, A longer period of 150 ° to 180 ° is set as the period on the edge side. When a longer 0 ° to 50 ° is set as the period Rx1, Sx1, Tx1, Ry1, Sy1, Ty1 on the front edge side, a period of 170 ° to 180 ° is set as the period on the rear edge side. In short, the period of the leading edge side and the period of the trailing edge side may be distributed within an electric angle of 60 °. Switching between the leading edge side 0 ° to (40 ° ± 10 °) and the trailing edge side (160 ° ± 10 °) to 180 ° is performed during the leading edge side 0 ° to 60 ° and the trailing edge side 120 ° to 180 °. Compared with the case of switching, the MOSFETs 31 to 36 that are turned on throughout the entire period (0 ° to 180 °) are any one, and the effect of improving controllability and reducing switching noise can be obtained.

  If switching noise is not a problem, it is not necessary to limit switching to only a specific phase period of each phase as in this embodiment. In this case, although switching noise increases, by performing switching (short circuit) at an appropriate timing in all phases, it is possible to further reduce harmonics and improve the power factor.

  Other configurations, operations, and effects are the same as those in the first embodiment. Therefore, the description is omitted.

  The above embodiments are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the scope of the invention. In these embodiments, the scope of the invention is included in the gist, and is included in the invention described in the claims and an equivalent scope thereof.

  The rectifier and the rectifier system according to the embodiment of the present invention can be used for an apparatus that converts an AC voltage into a DC voltage.

Claims (7)

A rectifier circuit for rectifying the voltage of the AC power supply;
A reactor provided between the AC power supply and the rectifier circuit;
A switching element for forming a short circuit for the AC power supply through the reactor and the rectifier circuit;
Detecting means for detecting an input current from the AC power source;
Detecting means for detecting the power factor;
A switching pattern for intermittently turning on the switching element at a predetermined phase of the voltage of the AC power supply is selected according to the detection current of the detection means, and the switching element is turned on / off based on the selected switching pattern Then, while sequentially correcting the selected switching pattern in a direction in which the detection power factor of the detection means is improved, the switching element is turned on / off based on the switching pattern for each correction, and for each correction. A control means for obtaining a difference between the switching pattern and the switching pattern at the time of selection, and if the obtained difference is less than a predetermined value, the correction is continued, and if the difference is greater than or equal to a predetermined value, control means for returning to the selection;
A rectifying device comprising: The AC power supply is a three-phase AC power supply,
The rectifier circuit is a series circuit for R phase in which a positive diode and a negative diode are connected in series, and an interconnection point between the two diodes is connected to the R phase of a three-phase AC power supply, and a positive diode and a negative diode are connected in series. An S-phase series circuit in which the connection point between the two diodes is connected to the S phase of the three-phase AC power source, and a positive diode and a negative diode are connected in series. Having a T-phase series circuit connected to the T-phase of the AC power source, converting the voltage of the three-phase AC power source into a DC voltage and outputting the DC voltage;
The switching element is connected in parallel to the diodes.
The reactor is provided between each phase of the three-phase AC power supply and the series circuit.
The control means includes a switching pattern for intermittently turning on the switching element on at least the leading edge side of a phase where each phase voltage of the three-phase AC power supply is a positive level and at least the leading edge side of a phase where the phase voltage is a negative level. Select according to the detection current of the detection means,
The rectifier according to claim 1.   A rectifying system comprising a plurality of the rectifiers according to claim 1 or 2, connecting the rectifiers in parallel, and performing data communication between the rectifiers. Each of the rectifiers stops on and off of each switching element when the detection current of any of the detection means becomes near zero or a predetermined value or more.
The rectifying system according to claim 3. Each of the rectifying devices grasps the detection currents of the respective detection means from each other by the data communication and obtains an average value thereof, and when each switching element is turned on / off so that the respective detection currents approach the average value. Adjust the on-period,
The rectifying system according to claim 3. Each of the rectifiers includes detection means for detecting an output current of each rectifier circuit, and when each output current of the rectifier circuit exceeds a predetermined value, the switching elements are turned on and off. ,
The rectifying system according to claim 3. Each of the rectifiers includes a detection unit that detects an output current of each rectifier circuit, and shuts off an output line of each rectifier circuit when the output current of any of the rectifier circuits becomes a predetermined value or more.
The rectifying system according to claim 3.

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