JP2012010507A - Dc power supply device - Google Patents

Abstract

To provide a DC power supply apparatus that can be reduced in price and reduced in size and can convert a three-phase AC power supply to a DC power supply with a high power factor.
A three-phase power factor correction circuit that simultaneously performs three-phase power factor improvement when converting a three-phase AC power source to a DC power source and supplies a DC power source to a load is provided in each phase of the three-phase AC power source It consists of three single-phase power factor correction circuits that simultaneously perform single-phase full-wave rectification and power factor correction, and form a DC power supply to the load in parallel. Each of the three single-phase power factor correction circuits has a current flowing through the switching element to the connection line between the negative output terminal of the single-phase full-wave rectifier circuit and the negative terminal of the output capacitor through the switching element. An output blocking diode for blocking output to the load side, and a second choke coil inserted between the negative output terminal of the single-phase full-wave rectifier circuit and the output blocking diode in the connection line; Prepare.
[Selection] Figure 1

Description

  The present invention relates to a DC power supply device that converts an AC power supply into a DC power supply, and more particularly to a DC power supply device that uses a three-phase AC power supply as an input.

  For example, in a power supply system for ships or aircraft, a three-phase generator that outputs a relatively large AC voltage such as AC 440 Vrms is used as a primary power source in a power supply system for ships or aircraft. In order to prevent the harmonic ripple current generated when full-wave rectifying the primary power supply from adversely affecting the primary power supply and other equipment sharing the primary power supply, There is a demand for a DC power supply device capable of AC / DC conversion with a power factor.

  Here, in a conventional DC power supply used in a ship or aircraft power supply system, a three-phase power factor correction circuit is connected to a three-phase generator via a choke coil and a three-phase bridge circuit A circuit constituted by a three-phase power factor control circuit for controlling the three-phase bridge circuit is known.

  In the three-phase bridge circuit, three sets of two series circuits of switching elements having diodes connected in antiparallel are connected in parallel to both ends of the output capacitor, and the series connection end of each series circuit is connected via a choke coil. This is a switching circuit connected to the corresponding phase of the phase generator, utilizing a three-phase full-wave rectification with six diodes, and a booster circuit with a choke coil for each phase, six switching elements, and six diodes. Perform power factor improvement.

  The three-phase power factor control circuit detects an AC voltage and an AC current input to the three-phase bridge circuit via a choke coil, performs dq conversion, and then performs calculations for power factor compensation control and current control. An operation for performing voltage control based on an output voltage from a three-phase bridge circuit to a load (for example, a DC / DC converter) is simultaneously performed to determine an ON / OFF ratio of each switching element of the three-phase bridge circuit. Configured.

  As a result, in the three-phase bridge circuit, the three-phase AC voltage is directly switched at a high speed with the switching frequency based on the ON / OFF ratio controlled in synchronization with the three-phase AC voltage, so that the current in phase with the input voltage waveform is sinusoidal. The three-phase full-wave rectification and the three-phase power factor improvement using the step-up operation are performed simultaneously.

  In Patent Document 1, a plurality of identically-designated converter modules are juxtaposed on the output side of a single-phase full-wave rectifier circuit having a diode bridge configuration to improve power factor, suppress harmonic ripples, and control the DC voltage of a specified voltage value. A converter device that can be generated is disclosed.

  Further, in Non-Patent Document 1, as a DC power supply device used in a single-phase AC power supply system that is currently widely used, an alternating current that flows during full-wave rectification is synchronized with an input voltage waveform in order to keep reactive power low. It is equipped with a single-phase power factor correction circuit that controls the flow so that it flows in a sinusoidal shape, and closes the power factor to 1, while suppressing harmonic ripple and causing stress on other devices that share the single-phase power source that is the primary power source A DC power supply is shown that is designed not to be added.

JP 2002-118966 A

Fuji Switching Power Supply Control IC Application Note “Power Factor Correction IC FA5500A / FA5501A” 09-01 Fuji Electric Device Technology Co., Ltd.

  However, in a configuration that implements three-phase power factor improvement and three-phase full-wave rectification all at once, the three-phase power factor control circuit needs to perform very complicated calculations, and therefore has its own complicated control program. It has been necessary to develop and write and configure a PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), etc., which has been a factor in increasing costs.

  In addition, since the output voltage of the three-phase generator used in power systems for ships and aircraft is as high as AC440Vrms, for example, the withstand voltage of each switching element of the three-phase bridge circuit is about 1000V, which can be switched at high speed. As a result, there is a problem that the entire circuit is enlarged for heat dissipation.

  Therefore, following the example shown in Patent Document 1, a single-phase power factor correction circuit shown in Non-Patent Document 1 is applied to each phase of the three-phase AC power supply to configure a three-phase power factor improvement circuit. Can be considered. According to this configuration, the price can be reduced and the size can be reduced. However, since the three single-phase power factor correction circuits supply DC power to a common load in parallel, a single-phase power factor correction circuit for a certain phase between the three single-phase power factor correction circuits. The current flowing through the switching element that is turned on becomes a return current that cannot be switched and returns to the corresponding phase of the three-phase AC power supply via the other two-phase single-phase power factor correction circuit. Has the problem of getting worse.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a DC power supply device that can be reduced in price and size and can convert a three-phase AC power supply to a DC power supply with a high power factor.

  In order to solve the above-described problems and achieve the object, the present invention provides a three-phase power for simultaneously performing a three-phase power factor improvement when converting a three-phase AC power source to a DC power source and supplying the DC power source to a load. The three-phase power factor correction circuit includes a single-phase full-wave rectification and a power factor correction simultaneously in each phase of the three-phase AC power source to provide a load to the load. It consists of three single-phase power factor correction circuits that form a DC power supply in parallel, and each of the three single-phase power factor correction circuits is a full-wave rectification of a single-phase power supply corresponding to the corresponding phase of the three-phase AC power supply. A single-phase full-wave rectifier circuit, a booster circuit including a first choke coil, a switching element, an output diode and an output capacitor, and the switching element is turned on / off in synchronization with an output voltage waveform of the single-phase full-wave rectifier circuit. By controlling OFF, the unit Control for switching the current output from the positive output terminal of the full-wave rectifier circuit and flowing through the first choke coil toward the output diode, and causing the output capacitor to form a DC voltage to be supplied to the load through the output diode. Inserted into a connection line between the circuit and a negative output terminal of the single-phase full-wave rectifier circuit and a negative terminal of the output capacitor, and a current flowing to the connection line through the switching element during a period when the switching element is ON. An output blocking diode for blocking output to the load side, and a second choke coil inserted between the negative output terminal of the single-phase full-wave rectifier circuit and the output blocking diode in the connection line; It is characterized by having.

  According to the present invention, the three-phase power factor correction circuit is composed of three single-phase power factor correction circuits provided for each phase. Then, the current flowing through the switching element turned on in the single-phase power factor correction circuit of a certain phase returns to the corresponding phase of the three-phase AC power supply via the other two-phase single-phase power factor correction circuit. Since the return current does not become a return current and the single-phase full-wave rectifier circuit returns directly through the second choke coil in the power factor improvement circuit for the own single phase, the first choke coil flows in the power factor improvement circuit for the own single phase. Both the current and the current flowing through the second choke coil can be controlled in the same sine wave shape. Therefore, it is possible to obtain a DC power supply apparatus that can be reduced in price and reduced in size, and that can convert a three-phase AC power supply to a DC power supply with a high power factor.

FIG. 1 is a block diagram showing a configuration of a DC power supply device according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a DC power supply device of a comparative example. FIG. 3 is a waveform diagram for explaining the operation.

  Hereinafter, embodiments of a DC power supply device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a block diagram showing a configuration of a DC power supply device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of a DC power supply device of a comparative example used for easy understanding. FIG. 3 is a waveform diagram for explaining the operation.

  In FIG. 1, a three-phase AC power source 1 is a three-phase generator that is used as a primary power source in a power system for ships or aircraft, for example. The output voltage of the three-phase generator 1 is, for example, AC440Vrms.

  In the DC power supply according to this embodiment, a three-phase power factor correction circuit is provided by single-phase power factor correction circuits 2 a, 3 a, and 4 a arranged in the U phase, V phase, and W phase of the three-phase generator 1. It is configured. In FIG. 1, the outputs of the single-phase power factor correction circuits 2a, 3a, and 4a are input in parallel to a DC / DC converter 5 serving as a common load. The DC / DC converter 5 converts each output voltage of the single-phase power factor correction circuits 2a, 3a, 4a into a DC voltage adapted to the specifications of the mounted electronic device, and supplies the DC voltage to the subsequent circuit.

  The single-phase power factor correction circuits 2a, 3a, and 4a have the same configuration, and include the single-phase full-wave rectifier circuit 10, the smoothing capacitor 11, the choke coil 12, the switching element 13, the drive circuit 14, and the current detection. 15, an output diode 16, an output capacitor 17, a control circuit 18, an output blocking diode 19, and a choke coil 20. Among them, the choke coil 12, the switching element 13, the output diode 16, and the output capacitor 17 constitute a booster circuit as a whole. The choke coils 12 and 20 have the same winding structure, and a normal mode choke coil configured by winding two windings around one core material can be used.

  The single-phase full-wave rectifier circuit 10 has a configuration in which four diodes are bridge-connected. One input terminal of the single-phase full-wave rectifier circuit 10 is connected to the U-phase output terminal of the three-phase generator 1 via the choke coil 21 in the single-phase power factor correction circuit 2a, and in the single-phase power factor correction circuit 3a, The single-phase power factor correction circuit 4a is connected to the W-phase output terminal of the three-phase generator 1 via the choke coil 23. The other input terminal of the single-phase full-wave rectifier circuit 10 is connected to the neutral point N of the three-phase generator 1 in common in the single-phase power factor correction circuits 2a, 3a, and 4a.

  One end of the choke coil 12 is connected to the positive output terminal of the single-phase full-wave rectifier circuit 10, one end of the choke coil 20 is connected to the negative output terminal of the single-phase full-wave rectifier circuit 10, and a smoothing capacitor is connected between both connection lines. 11 is connected. The positive output terminal and the negative output terminal of the single-phase full-wave rectifier circuit 10 are connected to the control circuit 18.

  The other end of the choke coil 12 is connected to the anode terminal of the output diode 16, and the cathode terminal of the output diode 16 is connected to one end (positive terminal) of the output capacitor 17 and the positive input terminal of the DC / DC converter 5. The other end of the choke coil 20 is connected to the cathode terminal of the output blocking diode 18, and the anode terminal of the output blocking diode 18 is connected to the other end (negative end) of the output capacitor 17 and the negative input end of the DC / DC converter 5. It is connected.

  The switching element 13 and the current detection are connected between the connection line between the other end of the choke coil 12 and the anode terminal of the output diode 16 and the connection line between the other end of the choke coil 20 and the cathode terminal of the output blocking diode 18. The container 15 is arranged in series. The drive circuit 14 drives the switching element 13 ON / OFF according to the drive signal from the control circuit 18. The current detector 15 detects a current that flows when the switching element 13 is turned on and outputs the detected current to the control circuit 18. The control circuit 18 also receives the terminal voltage of the output capacitor 17, that is, the output voltage to the DC / DC converter 5.

  In each step-up circuit (choke coil 12, switching element 13, output diode 16, and output capacitor 17) in each of the single-phase power factor correction circuits 2a, 3a, and 4a, the DC voltage charged to the smoothing capacitor 11 by the switching element 13 is high-speed. Switch. In the choke coil 12, electromagnetic energy proportional to the current 26 that flows during the period when the switching element 13 is ON is accumulated, and during the period when the switching element 13 is OFF, the current flows continuously in the same direction, The accumulated current 27 due to the electromagnetic energy is supplied to the output capacitor 17 via the output diode 16, and the output voltage (DC voltage) boosted in the output capacitor 17 is generated by charging.

  The control circuit 18 in each of the single-phase power factor correction circuits 2 a, 3 a, and 4 a receives an output voltage (AC input voltage) input from the single-phase full-wave rectifier circuit 10 and a current detector 15. While monitoring the current, the ON / OFF of the switching element 13 is controlled, and the voltage waveform of the AC input is in phase with the output current (AC input current) input from the single-phase full-wave rectifier circuit 10. In addition, by controlling the ON / OFF ratio of the switching element 13 so that the output voltage charged and generated in the output capacitor 17 becomes a predetermined voltage value, the power factor is brought close to 1 and the output voltage is stabilized. Do that.

  Here, the operation of the configuration including the output blocking diode 19 and the choke coil 20 will be described with reference to FIGS. 2 and 3 for easy understanding. 2, in the configuration shown in FIG. 1, the three-phase power factor correction circuit is configured with single-phase power factor improvement circuits 2 b, 3 b, 4 b instead of the single-phase power factor improvement circuits 2 a, 3 a, 4 a. It is shown. Other configurations are the same as those in FIG.

  The single-phase power factor correction circuits 2b, 3b, and 4b are single-phase power factor correction circuits shown in Non-Patent Document 1, respectively. In the single-phase power factor improvement circuits 2a, 3a, and 4a, the output blocking diode 19 and In this configuration, the choke coil 20 is omitted.

  In FIG. 3, the voltage waveform of each phase output from the AC generator 1 and the current waveform by the full-wave rectifier circuit are shown. Among the voltage waveforms of each phase, the U-phase voltage waveform is indicated by a solid line, and the V-phase voltage waveform and the W-phase voltage waveform are indicated by dotted lines. Since the current waveform by the full-wave rectifier circuit is associated with the voltage waveform, in the negative half cycle, it is represented as a waveform that does not invert the polarity and changes the same as the voltage waveform. The U-phase current waveform, V-phase current waveform, W-phase current It is written as a waveform. The U-phase current waveform is indicated by a solid line, and the V-phase current waveform and the W-phase current waveform are indicated by dotted lines.

  FIG. 3A shows an input voltage waveform and a U-phase current waveform for each phase when only a single-phase full-wave rectifier circuit having a diode bridge configuration is provided. In the case of only the single-phase full-wave rectifier circuit, the current waveform is shown to be a sine wave that is crushed by the generated harmonic ripple current. FIG. 3A shows an input voltage waveform and a U-phase current waveform of each phase in the configuration shown in FIG. FIG. 3C shows an input voltage waveform of each phase and a current waveform of each phase in the configuration shown in FIG.

  Now, in FIG. 2, the single-phase full-wave rectifier circuit 10 to which the U-phase voltage of the AC generator 1 is applied will be described using the single-phase power factor correction circuit 2 b that handles the U-phase of the AC generator 1. A rectified voltage (AC voltage) including a harmonic ripple having a waveform synchronized with the U-phase voltage is output between the positive electrode output terminal and the negative electrode output terminal. As a result, the smoothing capacitor 11 is charged, so that the U-phase current flowing out from the U-phase of the AC generator 1 is input to the single-phase full-wave rectifier circuit 10 with power supply noise being suppressed by the choke coil 21. The single-phase full-wave rectifier circuit 10 outputs the DC voltage including the harmonic ripple in the smoothing capacitor 11 that is output from the positive electrode output terminal toward the choke coil 12.

  The control circuit 18 gives a control command to the drive circuit 14 so that the ON time width of the switching element 13 is narrowed when the input voltage is low and gradually increases as the input voltage increases. The element 13 is caused to perform a switching operation in which the ON / OFF ratio is changed according to the input voltage.

  Then, the U-phase current output from the positive electrode output terminal of the single-phase full-wave rectifier circuit 10 toward the choke coil 12 passes through the switching element 13 to the current detector 15 during the period when the switching element 13 is ON. The current 26 flows to the connection line between the negative output terminal of the single-phase full-wave rectifier circuit 10 and the negative input terminal of the DC / DC converter 5. During the period when the switching element 13 is OFF, The current 27 is directed toward the positive input terminal of the output capacitor 17 and the DC / DC converter 5.

  In this case, the current (U-phase current) 27 flowing from the choke coil 12 toward the output diode 16 is switched by the switching element 13 in such a manner that the ON / OFF ratio changes. It flows in a sawtooth shape indicated by a solid line in (b). The control circuit 18 controls the ON / OFF ratio of the switching element 13 in synchronization with the U-phase input voltage waveform, and controls the current 27 flowing in a sawtooth shape so as to have the same sine wave shape as the input voltage. The sawtooth current 27 having a sine wave shape is output from the output diode 16 to the output capacitor 17 and charged in the output capacitor 17 to become an output voltage.

  On the other hand, since the noise component of the U-phase current flowing out from the U-phase of the AC generator 1 is suppressed by the choke coil 21, it becomes the same smooth sine wave as the input voltage to the control circuit 18. As a result, high power factor power conversion with less harmonic components can be performed.

  However, during the period when the switching element 13 is ON, the current 26 flowing to the connection line between the negative output terminal of the single-phase full-wave rectifier circuit 10 and the negative input terminal of the DC / DC converter 5 is a single-phase full-wave rectifier. The current is divided into a current 29 directed toward the negative output terminal of the circuit 10 and a current 30 directed toward the negative input terminal of the DC / DC converter 5. Then, the current 30 toward the negative input terminal of the DC / DC converter 5 is obtained from the negative output terminal of the single-phase full-wave rectifier circuit 10 and the negative input terminal of the DC / DC converter 5 in the single-phase power factor correction circuits 3b and 4b. The currents 31 and 32 flowing to the connection line between them become. The currents 31 and 32 are return currents that return to the U phase of the AC generator 1 without being subjected to switching control in the single-phase power factor correction circuit 2b.

  The negative half-cycle U-phase current shown in FIG. 3A is due to the return currents 31 and 32 to the U-phase of the AC generator 1. Switching control in the single-phase power factor correction circuit 2b is shown in FIG. Therefore, as in the case of only full-wave rectification by the diode bridge shown in FIG. As described above, in the single-phase power factor correction circuit 2b, the return currents 31 and 32 cannot be switched, so that the U-phase current includes a portion that does not have a sine wave shape as shown in FIG. Will get worse. The same applies to the single-phase power factor correction circuits 3b and 4b.

  In contrast, in this embodiment, as shown in FIG. 1, in each of the single-phase power factor correction circuits 2a, 3a, and 4a, the negative output terminal of the single-phase full-wave rectifier circuit 10 and the DC / DC converter 5 are used. An output blocking diode 19 and a choke coil 20 are interposed in a connection line between the negative input terminal of the first and second negative electrodes.

  According to the configuration shown in FIG. 1, in the single-phase power factor correction circuit 2 a, the negative output terminal of the single-phase full-wave rectifier circuit 10 and the negative input terminal of the DC / DC converter 5 during the period when the switching element 13 is ON. The output blocking diode 19 prevents the current branching in the direction from the current 26 flowing to the connection line between the two to the negative input end of the DC / DC converter 5 from flowing out to the single-phase power factor improving circuits 3a and 4a. Therefore, all of the current 26 passes through the choke coil 20 and returns to the negative output terminal of the single-phase full-wave rectifier circuit 10.

  At this time, the electromagnetic energy accumulated in the choke coil 20 turns on the output blocking diode 19 when the switching element 13 is turned off, draws current from the negative side of the output capacitor 17 and the DC / DC converter 5, and draws it out. The current is energized so as to flow from the output blocking diode 19 toward the negative electrode output terminal of the choke coil 20 to the single-phase full-wave rectifier circuit 10.

  That is, during the period when the switching element 13 is OFF, the U-phase current output from the positive output terminal of the full-wave rectifier circuit 10 is output diode due to the electromagnetic energy stored in the choke coil 12 when the switching element 13 is ON. 16 flows toward the output capacitor 17 and the DC / DC converter 5 via 16. At the same time, the current drawn from the output capacitor 17 and the negative electrode side of the DC / DC converter 5 through the output blocking diode 19 by the electromagnetic energy stored in the choke coil 20 when the switching element 13 is ON is the full-wave rectifier circuit 10. It will flow toward the negative electrode output end of.

  Thus, in the single-phase power factor correction circuit 2a, the U-phase current circulates while being subjected to switching control. Therefore, as shown in FIG. 3C, the U-phase current flows in a sawtooth shape indicating that switching control is performed in both the positive half cycle and the negative half cycle. The same applies to the single-phase power factor correction circuits 3a and 4a.

  Since the choke coils 12 and 20 have the same winding structure, a current having the same waveform as the current flowing through the choke coil 12 also flows through the choke coil 20. Therefore, the current controlled in a sine wave form by the control circuit 18 can be returned to the three-phase generator 1 in a sine wave form, and the power factor can be made as close to 1 as possible.

  As described above, according to this embodiment, a three-phase power factor correction circuit capable of AC / DC conversion at a very high power factor can be realized by using three single-phase power factor correction circuits. Price can be reduced without developing a simple control program. In addition, by manufacturing a plurality of single-phase power factor correction circuits having the same circuit configuration, it is possible to realize a high power factor DC power supply device for three phases, so that low-cost and efficient production can be achieved. Thus, the entire power supply system can be realized at a low price.

  Here, when the three-phase AC power source outputs a high voltage (for example, AC440Vrms) as in the case of a three-phase generator mounted on a ship or an aircraft, the switching element 13 needs to have a withstand voltage of 1000V or more. Therefore, it is necessary to perform switching at high speed and to have a very small resistance at the time of ON. Further, the output diode 17 and the output blocking diode 19 inserted in the output stage require a diode having high breakdown voltage and excellent reverse recovery characteristics.

  With respect to this point, in this embodiment, the switching element 13 has an on-resistance smaller than that of an insulated gate bipolar transistor (IGBT) or Si (silicon) MOSFET, which are switching elements widely used at present. A SiC (silicon carbide) MOSFET capable of high-speed switching is used, and the output diode 17 and the output blocking diode 19 have a higher breakdown voltage and superior reverse recovery characteristics than Si Schottky barrier diodes (Si-SBD). Since the SBD can be used, it is possible to obtain a further compact and highly efficient DC power supply device.

  As described above, the DC power supply device according to the present invention can be reduced in price and size, and is useful as a DC power supply device that can convert a three-phase AC power source to a DC power source with a high power factor. Or it is suitable as a direct-current power supply device used with the power supply system for aircrafts.

1 3-phase AC power supply (3-phase generator)
2a, 3a, 4a Single-phase power factor correction circuit 5 DC / DC converter (load)
10 single-phase full-wave rectifier circuit 11 smoothing capacitor 12 choke coil (first choke coil)
Reference Signs List 13 switching element 14 drive circuit 15 current detector 16 output diode 17 output capacitor 18 control circuit 19 output blocking diode 20 choke coil (second choke coil)

Claims (3)

A DC power supply device including a three-phase power factor correction circuit that simultaneously performs three-phase power factor improvement when converting a three-phase AC power source to a DC power source and supplies DC power to a load,
The three-phase power factor correction circuit performs three single-phase powers that simultaneously perform single-phase full-wave rectification and power factor correction in each phase of the three-phase AC power source to form a DC power source to the load in parallel. Consists of rate improvement circuit,
The three single-phase power factor correction circuits are respectively
A single-phase full-wave rectification circuit for full-wave rectification of a single-phase power supply corresponding to the phase of the three-phase AC power supply;
A booster circuit comprising a first choke coil, a switching element, an output diode and an output capacitor;
The switching element is ON / OFF controlled in synchronization with the output voltage waveform of the single-phase full-wave rectifier circuit, so that the first choke coil is output from the positive output terminal of the single-phase full-wave rectifier circuit as the output diode. A control circuit that controls switching of a current flowing toward the output, and forms a DC voltage to be supplied to the load from the output capacitor to the output capacitor;
Inserted into the connection line between the negative output terminal of the single-phase full-wave rectifier circuit and the negative terminal of the output capacitor, and the current flowing to the connection line through the switching element during the switching element is ON An output blocking diode that blocks output to
A second choke coil inserted between the negative output terminal of the single-phase full-wave rectifier circuit and the output blocking diode in the connection line;
A direct-current power supply device comprising:   The DC power supply device according to claim 1, wherein the switching element is a SiC MOSFET.   3. The DC power supply device according to claim 1, wherein each of the output diode and the output blocking diode is a SiC Schottky barrier diode.

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