JP2011061901A - Dc power supply apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a DC power supply apparatus capable of further increasing efficiency at low cost by operating at least three elements in mutually different phases. <P>SOLUTION: The DC power supply apparatus includes at least three reactors 3 connected to an output terminal of a rectifier 2 for rectifying an AC voltage of an AC power supply 1 to a DC voltage, a capacitor 6 that is connected to the respective reactors 3 via a diode 5 and smoothes the DC power, at least three switch elements 4 that are connected to the respective reactors 3 and form a power supply short-circuiting path via the rectifier 2, and a control means 10 of generating an operation signal for operating the respective switch elements by mutually different phase differences on the basis of one carrier and a plurality of modulation waves. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a DC power supply device that converts and controls an AC voltage into a DC voltage, for example. This is especially for harmonic current suppression and power factor improvement.

  For example, there is a DC power supply device that converts AC power in a commercial power source or the like into DC power. In such a DC power supply device, the power from the AC power supply is rectified. At this time, harmonic current suppression and power source power factor improvement are performed in the reactor, and a DC voltage is applied to the load side.

  Here, in order to further suppress the harmonic current and improve the power source power factor, some conventional DC power supply devices are provided with two sets of elements including a reactor, a switch element, and the like. Then, the current ripples (harmonic currents) of the two combined currents are reduced by operating the two switch elements in different phases (see, for example, Patent Document 1).

  In addition, there is a technique in which the cost is reduced by reducing the size and weight of the reactor by operating the two switch elements in opposite phases (for example, see Patent Document 2).

JP 2007-195282 A (FIG. 1, 0014) JP 2008-86107 A

  The technique as described above controls the output DC voltage to an arbitrary value, and controls it to a sinusoidal input current on which ripples due to switching are superimposed. Further, the two switch elements are operated at phases different from each other, the integrated value of the currents flowing through the two reactors is reduced, and the harmonic current that becomes noise is reduced. Here, in order to more effectively realize the reduction of the harmonic current and the like, it is better to use three or more (greater than two) switch elements, etc., instead of two, and increase the current component to be synthesized to achieve smoothing. Good.

  However, when three or more switch elements are operated at phases different from each other, it is not necessary to control the two switch elements simply to have opposite phases. Therefore, it is necessary to consider a specific signal generation method. At this time, although it is possible to configure the control means with a new circuit configuration or the like to perform control, the cost is increased accordingly.

  The present invention has been made in order to solve the above-described problems, and is capable of operating three or more elements in mutually different phases, and is capable of achieving high efficiency and reduced current ripple at a low cost. It was made in order to obtain a power supply device.

  A DC power supply device according to the present invention is connected to each reactor via a rectifier that rectifies an AC voltage of an AC power supply into a DC voltage, three or more reactors connected to an output terminal of the rectifier, and a DC power. Capacitors to be smoothed, three or more switch elements connected to each reactor and forming a power supply short-circuit path through a rectifier, one carrier signal, and a plurality of modulated waves are used. And a control means for generating an operation signal to operate with a phase difference.

  In the DC power supply device according to the present invention, since there are three or more reactors, switch elements, and diodes, and each switch element is operated with a different phase difference, the power source power factor is improved and the DC voltage is made constant. A highly efficient DC power supply device can be provided. Further, the reactor can be reduced in size and weight. By controlling the control means, it is possible to reduce the pulsation (ripple) of the current that flows through the reactors and to supply DC power with reduced harmonics that are noise.

1 is a circuit block diagram centering on a DC power supply device according to Embodiment 1. FIG. It is a wave form diagram of the operation signal etc. which operate three switch elements 4 with the same phase. It is a wave form diagram of the operation signal etc. which operate three switch elements 4 in a different phase. It is a waveform diagram of three operation signals and carriers related to a phase difference of 120 degrees. It is a wave form diagram for demonstrating the operation | movement based on a pseudo carrier. FIG. 6 is a waveform diagram of operation signals related to processing of the control means 10 of stages 2 and 5. FIG. 4 is a diagram illustrating a flowchart of a processing procedure related to processing of the control unit 10. It is a circuit block diagram of the control means 10 which concerns on Embodiment 2 of this invention. It is another circuit block diagram of the control means 10 concerning Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a circuit block diagram centering on the DC power supply according to Embodiment 1 of the present invention. In FIG. 1, an AC power source 1 supplies power by applying an AC voltage to a DC power source device. The rectifier 2 rectifies AC power related to the supply of the AC power supply 1.

  The reactors (inductors) 3a to 3c are respectively connected in parallel to the output terminal side of the rectifier 2 in order to improve the power factor. The switch elements 4a to 4c perform a switching operation based on an operation signal (PWM signal, gate signal) sent from the control means 10. In the on state, a short circuit path is formed through the AC power source 1, the rectifier 2, and the reactor 3. Here, since each set is connected in parallel and current is distributed, the current capacity of each of the switch elements 4 a to 4 c can be equal to or less than the rated current capacity of the load 7. For this reason, the switch elements 4a to 4c can protect the elements even if they are not more durable than necessary. Furthermore, current flows through the diodes 5a to 5c while the switch elements 4a to 4c are in the OFF state. In the following, when there is no need to distinguish or specify, subscripts may be omitted.

  In the present invention, three or more switch elements 4 are operated in different phases. For this reason, in the present embodiment, description will be made with three switch elements 4. Then, the switch element 4a, the reactor 3a, and the diode 5a are paired. Similarly, the switch element 4b, the reactor 3b, and the diode 5b are grouped, and the switch element 4c, the reactor 3c, and the diode 5c are grouped, and an operation process and the like related to the three groups of elements will be described. Here, in each set, one end of the reactor 3 is connected to the anode side of the diode 5 and the drain (collector) side of the switch element 4.

  Capacitor 6 is inserted in parallel with diodes 5a to 5c, switch elements 4a to 4c and load 7, and smoothes the power. The load 7 is connected in parallel with the capacitor 6. The voltage detector 8 detects the voltage across the capacitor 6. The current detector 9 detects the current flowing out from the rectifier 2.

  The control means 10 has, for example, one or a plurality of microcomputers (microcomputers). Based on the detection values of the voltage detector 8 that detects the DC voltage and the current detector 9 that detects the DC current, an operation signal is output to each of the switch elements 4a to 4c. Then, the switching operation of the switch elements 4 a to 4 c is controlled by PWM (Pulse Width Modulation) and the DC voltage and DC current supplied to the load 7 are controlled. Here, in order to realize a function capable of PWM control (hereinafter referred to as a PWM function), the control means 10 is assumed to have one PWM timer for obtaining timing for turning on / off a pulse at a carrier frequency.

  FIG. 2 is a waveform diagram for illustrating generation of operation signals when the three switch elements 4a to 4c are operated in the same phase. Here, an operation signal is generated by a triangular wave comparison that compares a modulated wave with a triangular wave (carrier) signal generated at a carrier frequency (the same frequency as the frequency related to the switching operation of the switch element 4). Operating the three switch elements 4 in the same phase is synonymous with generating the same operation signal.

  FIG. 3 is a waveform diagram for illustrating generation of an operation signal when the three switch elements 4a to 4c are operated at phases different from each other. In FIG. 3, the phases of the carriers (triangular waves) for PWM control of the switch elements 4a to 4c are different from each other. Here, the phase difference of 120 degrees is given to each other so that the combined vector of the waves related to the three operation signals becomes zero. In this way, by comparing the three carriers operating at the carrier frequency with one modulation wave, a triangular wave can be used to generate operation signals having different phases for the three switch elements 4a to 4c.

  On the other hand, for example, when two switch elements are operated at phases different from each other, the current ripple reduction effect becomes the highest when the combined vector is driven at a phase difference of 180 degrees. Here, a signal having a phase difference of 180 degrees may be compared by inverting the reference carrier so as to have an opposite phase. Therefore, the signal generation is not so complicated and can be easily generated by a general logic circuit or the like. For example, existing commercially available microcomputers often have a PWM function as a standard function that can output an operation signal and an operation signal having a phase difference of 180 degrees.

  However, when three or more switch elements are operated in different phases, the signal is not simply inverted. For example, in order to perform PWM control of each switch element 4, it is conceivable to configure a microcomputer that generates an operation signal by comparing three or more different carriers and a modulated wave. However, such a microcomputer is not general, and is configured by manufacturing a custom IC (special circuit), designing with an external circuit, or the like. Custom ICs, external analog circuits, etc. are not versatile, so they are expensive and difficult to reduce.

  Therefore, in the present embodiment, for example, a commercially available microcomputer for driving an electric motor (motor) having a PWM function (hereinafter referred to as a PWM microcomputer) is used as the control means 10. Then, three or more operation signals having different phases are generated, and the ripple of the combined current is reduced by the switching operation of the three or more switch elements 4. For example, when the AC power supply 1 is a single-phase power supply, it is possible to control the power supply voltage to a similar, substantially sinusoidal input current by combining three operation signals, and when the AC power supply 1 is a three-phase power supply, it is rectangular. It can be controlled to a wavy input current. Here, the PWM function in the PWM microcomputer is to generate an operation signal by comparing one carrier and a plurality of modulated waves (the motor is usually three-phase because it has three phases).

  FIG. 4 is a waveform diagram of three operation signals and a carrier (triangular wave) related to a phase difference of 120 degrees. 4A shows a waveform with a duty ratio (duty ratio) = small, FIG. 4B shows a waveform with a duty ratio = medium, and FIG. 4C shows a waveform with a duty ratio = large. Further, the carrier in FIG. 4 represents one of the three carriers for generating three operation signals. In FIG. 4B, in the three operation signals during the half carrier period (half period in the carrier), an edge occurs only once, so that the PWM microcomputer can output an operation signal having a pulse with a predetermined duty ratio. . Here, the edge means a change in the polarity of the voltage of the operation signal from Hi to Lo or Lo to Hi.

  However, as shown in FIGS. 4A and 4C, if the duty ratio is different, as shown in the operation signals of the switch elements 4b and 4c, an edge is generated twice in the operation signal during the half carrier period. There are things to do. In this case, it will concentrate on one of the half carrier periods. On the other hand, the switch element 4a has no problem because the edge appears only once in the half carrier period. This is because the operation signals of the switch elements 4b and 4c are generated by a triangular wave comparison using a triangular wave having a phase different from that of the triangular wave shown in FIG. Therefore, a PWM microcomputer having only one carrier can basically generate one operation signal regardless of the duty ratio, but has a duty ratio of 50 for the other two operation signals. Only motion signals around% can be generated.

  Therefore, the control means 10 first divides the original carrier period and generates 1 / n times the frequency (the frequency is n) when generating the operation signals having different phases from each other to the n switching elements 4 (n ≧ 3). Have or generate pseudo carriers that are triangular waves that are doubled). In the case of dividing by n, if the switching operation is performed so as to have a phase difference of 360 / n degrees, the combined vector can be set to 0, and the ripple of the combined current can be reduced to the maximum. Become. In the present embodiment, since three switch elements 4 are provided, n = 3.

  FIG. 5 is a waveform diagram for explaining the operation based on the pseudo carrier. The waveforms in FIGS. 5A to 5C represent three carriers having a phase difference of 120 degrees from each other. FIG. 5D shows a pseudo carrier having a pseudo carrier frequency obtained by triple the carrier frequency in the carrier. Further, FIG. 5 (e) shows stages assigned for every rising and falling of the triangular wave in the pseudo carrier. At this time, six stages are formed based on the rising and falling of the pseudo carrier having the triple frequency. For example, if the pseudo carrier is 4 times, there are 8 stages, and if the pseudo carrier is 5 times, 10 stages.

  In the triangular wave that is a pseudo carrier shown in FIG. 5D, the triangular points (a) to (c) that originally have a phase difference of 120 degrees coincide with the peak points (black points in FIG. 5). . The PWM microcomputer has a function of changing the duty at this peak point (generally called a peak / valley). For this reason, when the duty ratio is more than 0% and less than 100%, an edge of the operation signal is generated between the peaks and valleys that are the peak points. Accordingly, in the stages assigned to the six stages, the edges of the three operation signals are always only once in the same stage. Therefore, when the PWM microcomputer performs processing based on the pseudo carrier, even if the operation signal having the duty ratio as shown in FIGS. 4A and 4C is generated, the peak in the triangular wave that is the pseudo carrier is generated. Edge generation in the three operation signals between the valleys is less than once.

  From the above, by switching based on a pseudo carrier having a pseudo carrier frequency that is three times the original carrier frequency, in a PWM microcomputer having only one carrier, the DC power supply device can be operated efficiently. Three operation signals having different phases can be generated. For this reason, it can be constructed with an inexpensive control circuit having the largest circulation amount. Further, since a plurality of operation signals can be generated from one carrier, it is only necessary to have one PWM timer.

  Here, the generation of three operation signals having different phases using the pseudo carrier can be mechanically realized, but the same operation signal as that generated by the original carrier is generated based on the pseudo carrier. In order to do this, another device is needed.

  For example, when a modulated wave with a modulation factor Kc = 20% and a pseudo carrier having a pseudo carrier frequency three times the carrier frequency are compared, an operation signal having a signal frequency of three times (the period for switching is 1/3) Three (pulse width 1/3) are generated. Here, the modulation rate Kc represents the position (height) of the modulated wave with respect to the carrier, and is the same as the duty ratio in the carrier period. Even with such an operation signal, the duty ratio and the like do not change ideally, but the number of pulses per time (one period) (the number of edges) increases, so that the efficiency decreases, for example, the switching loss increases.

  Therefore, in the present embodiment, the control means 10 performs processing related to the modulation rate for each of the six stages, and processes so that an operation signal (one continuous pulse) based on the original carrier is generated ( The three operating signal pulses based on the pseudo carrier are combined into one). At that time, the polarity (positive or negative) is determined based on the modulation factor Kc and the stage.

  Regarding the processing related to the processing of the control means 10 as described above, the (original) operation signal generated by the triangular wave in FIG. 5A and the operation signal generated by the triangular wave of the pseudo carrier in FIG. 5D. A description will be given based on the comparison. Here, in FIG. 5 (e), the stage immediately before the peak point that is the valley of the triangular wave in FIG. 5 (a) is defined as stage 0 as the stage start point, and the six stages are sequentially designated as stages 0 to 5, respectively. To do.

  Since the pseudo carrier frequency is three times higher than the original carrier frequency, if the pulse width in the operation signal is made the same, the modulation rate in the modulated wave compared with the pseudo carrier is tripled and the pulse width is tripled. Like that. Here, the modulation rate at the original carrier is Kc, and the pseudo modulation rate representing the modulation rate at each stage at the pseudo carrier is Kc ′. Here, since the pseudo modulation rate Kc ′ is different for each stage, the control means 10 performs the calculation for each stage.

  If the modulation factor Kc is greater than 0 and less than about 33% (1/3), the pseudo modulation factor Kc ′ is 1 or less even if the modulation factor Kc is tripled. Therefore, an edge is generated in the period of stage 0 and stage 1 (stage 0 rises and stage 1 falls). An operating signal is generated. Here, in stage 2, stage 3, stage 4 and stage 5, the pseudo modulation rate Kc 'is 0 or less, so it is set to 0. Here, since there are three switch elements 4 in the present embodiment, the modulation rate Kc is divided into cases with approximate values of 1/3 and 2/3.

  When the modulation factor Kc is about 33% (1/3) or more, the tripled value exceeds 1, so that an edge is generated in stages other than stage 0 and stage 1. Therefore, the pseudo modulation rate Kc ′ in the stage 0 and the stage 1 is set to 100% (1. all on state).

  When the modulation factor Kc is greater than or equal to about 33% (1/3) and less than about 66% (2/3), an edge occurs during the stage 2 and stage 5 (stage 5 rises and stage 2 falls). . If the modulation factor Kc is tripled, it will exceed 1, but since the stage 0 and stage 1 are all on, the value obtained by subtracting 1 (value relating to the all-on state) from the value obtained by multiplying the modulation factor Kc by 3 Is the original pseudo-modulation rate Kc ′ during the stage 2 and stage 5 periods.

  FIG. 6 is a waveform diagram of operation signals for explaining the processing of the control means 10 when the period edges of the stage 2 and the stage 5 occur. Normally, since the stage 1 period is all on, the operation signal in the stage 2 period starts from the on state. However, if the operation signal is generated by the triangular wave comparison, the stage 2 period is off. It will start from the state. Similarly, the period of stage 5 starts from the off state, an edge is generated, the pulse rises, and all the on states in stage 0 are connected. However, when the operation signal generation by the triangular wave comparison is performed, stage 2 is It ends in the off state. Therefore, pulses are not continuously generated and are interrupted (FIG. 6A).

  This is because the polarities of the carrier and the pseudo carrier are different in the stage 2 and stage 5 periods. For example, during the stage 2 period, the triangular wave that is the original carrier rises to the right while the triangular wave that becomes the pseudo carrier falls to the right. In the stage 5 period, the triangular wave of the original carrier is descending to the right, while the triangular wave of the pseudo carrier is rising to the right. For this reason, the result of the triangular wave comparison cannot be used as it is.

  Therefore, in the stage 2 and the stage 5 in which the modulation rate Kc is about 33% or more and less than 66%, the control unit 10 sets a value obtained by subtracting a value that is three times the modulation rate Kc from 2 to the pseudo modulation rate Kc ′ (hereinafter referred to as “pseudo modulation rate Kc ′”). The triangular wave comparison is performed as a special pseudo modulation rate Kc ′. Then, a signal obtained by inverting the result is output. The original pseudo modulation rate Kc ′ in the period of stage 2 and stage 5 is maintained, and an operation signal that does not divide the pulse is generated (FIG. 6B).

  When the modulation rate Kc is 33% (1/3) or more and less than 66% (2/3), the pseudo modulation rate Kc ′ is 0 or less during the stage 4 and stage 3 periods. To do.

  When the modulation factor Kc is about 66% (2/3) or more and less than 100% (1.00), the tripled value exceeds 2, so that an edge occurs during the stage 3 and stage 4 (stage 4). Rises and stage 3 falls). For this reason, not only the stage 0 and the stage 1, but also the pseudo modulation rate Kc ′ in the stage 2 and the stage 5 is 100% (1. all-on state). A value obtained by subtracting 2 from the value obtained by multiplying the modulation rate Kc by 3 is the pseudo modulation rate Kc ′ during the stage 3 and stage 4 periods.

  FIG. 7 is a flowchart illustrating a processing procedure related to processing of the control means 10. FIG. 7 shows the above-described processing flow. The control means 10 determines whether the modulation factor Kc is 34% or more and 67% or less (S1). If the modulation rate Kc is not about 33% or more and less than about 66%, the normal pseudo modulation rate Kc ′ at each stage is calculated based on the modulation rate Kc (S3). Here, when the value obtained by multiplying the modulation factor Kc by 3 and subtracting 1 or 2 is 1 or more, the pseudo modulation rate Kc ′ is 1, and when the value is 0 or less, the pseudo modulation rate Kc ′ is 0. To do. A triangular wave is compared based on the calculated pseudo modulation rate Kc '(S4), and an operation signal is generated (S5).

  On the other hand, if it is determined in S1 that the modulation factor Kc is not less than about 33% and less than about 66%, it is further determined whether or not the operation signal is generated in the stage 2 or stage 5 (S2). If the period is not stage 2 or stage 5, a normal pseudo modulation rate Kc 'is calculated (S3), and the subsequent processing is performed.

  If it is determined in S2 that the operation signal related to the period of stage 2 or stage 5 is generated, a special pseudo modulation factor Kc 'is calculated (S6). Then, a triangular wave comparison is performed based on the calculated pseudo modulation rate Kc ′ (S7), and an operation signal in which the signal is inverted is generated (S8).

  Here, in FIG. 6 and the like, the generation of the operation signal using the triangular wave of FIG. 5A as the original carrier has been described. For example, regarding the generation of the operation signal when the operation signal and the triangular wave of FIG. 5B having a phase difference of 120 degrees are used as the carrier, the stage 1 and the stage 4 are the same as the stage 2 and the stage 5 in the above description. Therefore, it should be replaced. Similarly, stage 0 and stage 3 correspond to the generation of the operation signal when the triangular wave in FIG. 5C is used as a carrier.

  From the above, there is one triangular wave of the pseudo carrier, and there are three pseudo modulated waves corresponding to the three triangular waves having different phases, so that three operations having different phases by the combination of one carrier and three modulated waves 3 are performed. A signal can be generated. For this reason, in the PWM microcomputer, three operation signals having different phases can be easily generated.

  Here, in the above description, 1/3 and 2/3 are numbers that are not divisible when generating the operation signal for switching the three switch elements 4 at different phases. The case of Kc was divided. For example, in the generation of operation signals related to n or more switch elements 4 of 4 or more, by dividing the case according to the number of the switch elements 4 (the number of sets of the reactor 3, the switch element 4, and the diode 5), it is commercially available. Needless to say, this can be realized by a microcomputer having a PWM function.

  As described above, in the DC power supply device of the first embodiment, there are three or more sets of the reactor 3, the switch element 4, and the diode 5, and the switch elements 4 of each set are operated with different phase differences. Therefore, it is possible to provide a high-efficiency DC power supply device that realizes zero current switching and the like, improves the power source power factor, and makes the DC voltage constant. Further, the reactor can be reduced in size and weight. At this time, the control means 10 performs control so that the amplitude width caused by the pulsation in the combined current obtained by synthesizing the currents of each set is smaller than the amplitude width caused by the pulsation (ripple) generated in the current flowing through the reactor 3 of each set. Therefore, there are few pulsations, noise can be reduced, and stable DC power can be supplied to the load 7. Furthermore, since the direct-current power supply device of the first embodiment has three or more sets of switch elements 4 and the like, it is possible to further suppress harmonic current and the like than the two sets of direct-current power supply devices.

  Further, the control means 10 generates an operation signal for each group of the switch elements 4 by comparing the pseudo carrier having a frequency obtained by multiplying the carrier frequency by a triangular wave with the modulated wave corresponding to the number of the group. Therefore, not only two operation signals whose phases are different by 180 degrees, but also three or more operation signals whose phases are different from each other can be easily generated. In particular, when there are three switch elements 4 as in the present embodiment, a microcomputer for driving an electric motor having a PWM function can be applied, so that the control means 10 (DC power supply device) is configured at low cost. Can do. At this time, since the operation signal is inverted and the generation method is changed and adjusted for the part having a polarity different from that of the original carrier, the operation generated by the carrier even in the triangular comparison with the pseudo carrier is performed. The same signal as the signal can be generated. Further, since the current capacity of each switch element 4 is set to be equal to or lower than the rated current capacity of the DC power supply device, the elements can be protected, the durability can be improved, and the life can be extended.

Embodiment 2. FIG.
FIG. 8 is a circuit block diagram showing a configuration example of the control means 10 according to the second embodiment of the present invention. As described above, the control means 10 outputs an operation signal to the switch elements 4a to 4c based on the detection values of the voltage detector 8 and the current detector 9, and controls the DC voltage and the DC current.

  First, in order to make the DC voltage constant, the PI control unit 11 compares the DC voltage command value Vdc * with the voltage detection value from which high-frequency component noise has been removed in the low-pass filter 15, and the deviation becomes zero. In this way, PI control is performed. The value output as a result of the control by the PI control unit 11 is the DC current command value Idc *.

  The PID control unit 12 compares the DC current command value Idc * with the current detection value from which high-frequency component noise has been removed in the low-pass filter 16 and performs PID control so that the deviation becomes zero. The value output as a result of control by the PID control unit 12 is the modulation factor Kc described in the first embodiment. If the direct current command value Idc * is controlled to be constant, when the alternating current power supply 1 is a three-phase power supply, it can be controlled to a rectangular wave input current. When the AC power supply 1 is a single-phase power supply, it can be controlled to a sinusoidal input current by controlling the direct current command value Idc * so as to approximate a half-wave rectified waveform of the current voltage. .

  Here, in the present embodiment, the PID control unit 12 is configured by a standard microcomputer. Therefore, direct current control is performed by PID control. For example, in general, in the case of digital control, a control delay occurs in the time from control calculation to PWM operation (actual operation) by signal output. This control delay is caused by dead time due to discretization of digital control. When the control delay occurs, the phase is delayed, and the controllability of the switch element 4 is deteriorated. Here, it is known that differential control is used to perform phase lead compensation. Therefore, in this embodiment, the PID controller 12 performs a differential operation to control the phase lead compensation.

  Then, based on the modulation factor Kc related to the output of the PID control unit 12, the PWM calculator 13 generates an operation signal for operating the switch elements 4a to 4c with different phase differences as described in the first embodiment. And output to the switch elements 4a to 4c.

  As a result, it is possible to easily configure the control means 10 that can operate three or more switch elements 4 even with an existing microcomputer having a PWM function, and to provide an inexpensive and highly efficient DC power supply device. .

  FIG. 9 is a circuit block diagram showing another configuration example of the control means 10 according to Embodiment 2 of the present invention. As shown in FIG. 8, the phase lead compensation for dead time is set as a pseudo-differentiation, and the output of the gain unit 14 is added using the high-pass filter 17 to obtain the modulation factor Kc. Needless to say, it has the same effect as the control means 10. FIG. 9 shows a circuit block for controlling the input current to a rectangular wave shape.

  By configuring the control means 10 as described above, when the AC power supply 1 is a single-phase power supply, the power supply voltage can be controlled to a similar substantially sinusoidal input current, and the AC power supply 1 is a three-phase power supply. In this case, the input current can be controlled to a rectangular wave input current. As a result, the harmonic current can be reduced, power source power factor improvement and constant DC voltage control can be realized, and current ripple can be reduced by operating a plurality of switch elements with different phase differences in an inexpensive configuration. Noise suppression and a smaller and lighter reactor can be realized.

Embodiment 3 FIG.
Although not specifically shown in the above-described embodiment, wide band gap semiconductors such as SiC (silicon carbide) -based and GaN (gallium nitride) -based devices may be used as the materials of the switch element 4 and the diode 5. In the case of a wide band gap semiconductor, loss due to switching operation or the like can be greatly reduced, so that the carrier frequency is made higher than in the case where the switch element 4 and the diode 5 of the Si (silicon) device are used. Can do.

  Further, by operating three or more switch elements 4 with operation signals having different phase differences, the frequency of the combined current becomes higher than the switching frequency. For this reason, it is possible to provide a DC power supply apparatus that can significantly reduce noise and reduce noise countermeasure costs.

  As an application example of the present invention, the present invention can be used for a DC power supply device for a load that consumes power by DC. In particular, it can be used as a power supply device for an inverter that is a DC / AC converter, and can be applied to an inverter that drives a permanent magnet motor, thereby realizing energy saving, a low-cost and low-noise DC power supply configuration. For this reason, in addition to an air conditioner, a refrigerator, and a washing / drying machine, it can be applied to a variety of home appliances such as a refrigerator, a dehumidifier, a heat pump water heater, a showcase, and a vacuum cleaner. Further, it can be applied to power supply devices such as fan motors, ventilation fans, and hand dryers.

  DESCRIPTION OF SYMBOLS 1 AC power supply, 2 Rectifier, 3a-3c reactor, 4a-4c switch element, 5a-5c diode, 6 Smoothing capacitor, 7 Load, 8 Voltage detector, 9 Current detector, 10 Control means, 11 PI control part, 12 PID control unit, 13 PWM calculator, 14 gain unit, 15, 16 low-pass filter, 17 high-pass filter.

Claims (9)

Three or more reactors connected to the output terminal of the rectifier that rectifies the AC voltage into a DC voltage;
A capacitor connected to each reactor via a diode and smoothing DC power;
Three or more switch elements connected to each reactor and forming a power supply short-circuit path through the rectifier;
A direct-current power supply device comprising: control means for generating an operation signal for operating each switch element with a different phase difference based on one carrier and a plurality of modulated waves.   The operation signal of each switch element is generated based on a pseudo carrier having a frequency obtained by multiplying the operation frequency of the three or more switch elements by the number of switch elements. DC power supply.   The control means generates an operation signal of one pulse per cycle, and therefore generates the operation signal when the edge of the pulse occurs in a period in which the polarities of the waveforms of the carrier and the pseudo carrier are different. The DC power supply device according to claim 2, wherein the DC power supply device is performed based on different procedures.   The control means generates the operation signal by inverting a signal generated by switching a time during which the pulse is on and a time during which the pulse is off during the periods of different polarities. 3. The DC power supply device according to 3.   5. The DC power supply device according to claim 1, wherein the control unit has one PWM timer for generating a PWM operation signal for each switch element. 6.   The control means generates the operation signal of each switch element so that a pulsation width in a combined current of currents flowing through each reactor is smaller than a pulsation width in a current flowing through one reactor. The direct-current power supply device in any one of thru | or 5.   The DC power supply device according to any one of claims 1 to 6, wherein the DC power supply device has a rated current capacity larger than a current capacity of the switch element.   The DC power supply device according to any one of claims 1 to 7, wherein the control means includes a microcomputer having a PWM function for driving an electric motor, and generates an operation signal of each switch element.   9. The DC power supply device according to claim 1, wherein at least one of the switch element and the diode is formed of a wide band gap semiconductor.

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