JP2008092640A - Three-phase rectifier device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-phase rectifier device capable of reducing power source harmonics and controlling a power source power factor to be 1. <P>SOLUTION: The device is provided with a three-phase rectifying circuit 2 having diodes D1-D12 and switching elements Q1-Q6, rectifying AC power of three-phase AC reactors La-Lc and outputting the rectified power to smoothing capacitors C1, C2; a coordinate converter 34 for converting a first coordinate current of the three-phase AC power source into a second coordinate current on the basis on the power source voltage phase calculated in a phase calculator 33 based on the voltage of the three-phase AC power source; PI controllers 40, 36 for generating a second coordinate system voltage command value on the basis of an effective branched current command value generated in a PI controller 38 on the basis of a smooth capacitor voltage and a reference voltage value, and a predetermined invalid branched current command value and a second system current; and a spatial voltage vector modulation calculating section 42 for calculating a voltage vector to be selected on the basis of the first coordinate system voltage command value obtained by converting the second coordinate system voltage command value by a coordinate converter 41 on the basis of the power source voltage phase and the smoothing capacitor voltage, calculating a switching pattern having an order of the least number of times of switching of each switching element, and generating a command signal to each switching element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a three-phase rectifier that converts three-phase alternating current into direct-current power.

  FIG. 12 is a circuit configuration diagram of a conventional three-phase rectifier. The three-phase rectifier shown in FIG. 12 is a three-level converter called a VIENNA rectifier. In this three-level converter, three-phase AC power supplies Va, Vb, Vc are connected in series with three-phase AC reactors La, Lb, Lc, and two diodes are connected in series to each phase. When a switching element is connected to the middle point of the diode connected to the switch and the switching element is turned on, the switching element is connected to the middle point of the two smoothing capacitors C1 and C2 connected in series.

  This circuit will be described in detail. Three-phase AC reactors La, Lb, and Lc are connected in series to the three-phase AC power sources Va, Vb, and Vc in correspondence with them. To the three-phase AC reactors La, Lb, and Lc, a three-level converter unit 2 including 12 diodes D1 to D12 and 6 IGBT switching elements Q1 to Q6 is connected.

  The three-level converter unit 2 corresponds to three groups including four diodes among the twelve diodes D1 to D12, and each group includes first to fourth diodes D1 to D4, D5 to D8, It has three series circuits formed by connecting D9 to D12 in series with the same polarity.

  In addition, the three-level converter unit 2 includes a first switching unit including a switching element Q1 and a switching element Q2 connected in series between a connection point between the diode D1 and the diode D2 and a connection point between the diode D3 and the diode D4. A second switching circuit composed of a switching element Q3 and a switching element Q4 connected in series between a connection point of the circuit, a connection point of the diode D5 and the diode D6, and a connection point of the diode D7 and the diode D8; A third switching circuit including a switching element Q5 and a switching element Q6 connected in series is provided between a connection point of the diode D10 and a connection point of the diode D11 and the diode D12.

  Between the connection point where the connection points of the switching elements Q1, Q3, Q5 and the switching elements Q2, Q4, Q6 are connected in common and the connection point where the cathodes at both ends of each of the three series circuits are connected together, A smoothing capacitor C1 is connected. Between the connection point where the connection points of the switching elements Q1, Q3, Q5 and the switching elements Q2, Q4, Q6 are connected in common and the connection point where the anodes at both ends of each of the three series circuits are connected together, A smoothing capacitor C2 is connected.

  The connection point between the diode D2 and the diode D3 is connected to the three-phase AC reactor La, the connection point between the diode D6 and the diode D7 is connected to the three-phase AC reactor Lb, and the connection point between the diode D10 and the diode D11 is three-phase. It is connected to AC reactor Lc. Each gate terminal of the switching elements Q1 to Q6 is connected to a control circuit (not shown), and on / off of the switching elements Q1 to Q6 is controlled by this control circuit.

  The three-level converter circuit as shown in FIG. 12 has an advantage that the withstand voltage of the semiconductor element can be halved as compared with a full bridge converter circuit including six diodes and six switching elements.

  In general, a converter circuit is aimed at reducing power supply harmonics and setting the power supply power factor to 1 in order to regulate power supply harmonics and improve power utilization. That is, in this three-level converter, it is required to set the input power factor to 1, stably control the voltages of the smoothing capacitors C1 and C2, and also to have controllability capable of instantaneously responding to load fluctuations and input voltage fluctuations. Is required.

In order to solve this problem, the converters described in Patent Document 1 and Patent Document 2 turn on the switching element once every half cycle of the power supply voltage, thereby reducing the switching loss of the switching element and the power supply harmonics. We are trying to reduce it.
Japanese Patent Laid-Open No. 10-174442 JP 2000-295853 A

  However, in the converters described in Patent Document 1 and Patent Document 2, since the switching element is switched only once in a half cycle of the power supply voltage, the power supply harmonics are reduced only when the load is known in advance. On the other hand, in the PWM (pulse width modulation) system in which switching is performed at a high frequency, power supply harmonics are reduced, but switching loss is increased, and high efficiency of the apparatus is not achieved.

  Although there is a method of reducing the carrier frequency as a method of reducing the loss of the switching element, it has a disadvantage that the control performance is lowered.

  An object of the present invention is to have a control algorithm for selecting a switching pattern of a switching element so that switching loss does not increase as much as possible while using PWM control, and can reduce power supply harmonics and set the power factor to 1. The object is to provide a three-phase rectifier.

  In order to solve the above-mentioned problem, the invention described in claim 1 includes a three-phase AC reactor connected in series to a three-phase AC power source, a plurality of diodes, and a plurality of switching elements. A three-phase rectifier circuit that rectifies the three-phase alternating current and outputs the same to a smoothing capacitor, a phase calculating means that calculates a power supply voltage phase based on the voltage of the three-phase alternating current power supply, Based on the first coordinate conversion means for converting the current in the first coordinate system of the three-phase AC power source into the current in the second coordinate system, and the effective current command value is generated based on the voltage of the smoothing capacitor and the reference voltage value. A voltage command value for the second coordinate system is generated based on the current control means, the current in the second coordinate system from the first coordinate conversion means, the effective current command value, and a predetermined reactive current command value. To do And second coordinate conversion means for converting the voltage command value of the second coordinate system from the voltage control means into a voltage command value of the first coordinate system based on the power supply voltage phase from the phase calculation means. And the voltage vector selected based on the voltage command value of the first coordinate system from the second coordinate conversion means and the voltage of the smoothing capacitor, and the switching frequency of each switching element is the smallest order. Spatial voltage vector modulation means for calculating a switching pattern and generating a command signal for each of the switching elements is provided.

  According to a second aspect of the present invention, in the three-phase rectifier according to the first aspect, the three-phase rectifier circuit corresponds to three groups each including four diodes out of twelve diodes. Are provided in correspondence with the three series circuits, wherein the first to fourth diodes are connected in series with the same polarity, the connection point between the first diode and the second diode, and Three switching circuits comprising a first switching element and a second switching element connected in series between a connection point of a third diode and the fourth diode, the first switching element, and the second switching element A first smoothing capacitor connected between a connection point commonly connected to each other and a connection point commonly connected to the cathodes at both ends of each of the three series circuits, and the first switching element, A second smoothing capacitor connected between a connection point commonly connected to the connection point of the second switching element and a connection point commonly connected to the anodes at both ends of each of the three series circuits; The connection point between the second diode and the third diode is a three-level converter circuit connected to the three-phase AC reactor.

  According to a third aspect of the present invention, in the three-phase rectifier according to the first or second aspect, the spatial voltage vector modulation means calculates an application time of the selected voltage vector.

  According to the present invention, the spatial voltage vector modulation means determines the voltage vector selected based on the voltage command value of the first coordinate system from the second coordinate conversion means and the voltage of the smoothing capacitor and the number of switching times of each switching element. Since the switching pattern in the smallest order is calculated and the command signal to each switching element is generated, the switching frequency of the switching element can be reduced compared with the conventional method, the switching loss does not increase, and the power supply harmonics And the power factor can be made 1. Further, it can be realized without deteriorating the control performance, the component cost and the size of the apparatus.

  Hereinafter, embodiments of the three-phase rectifier of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a circuit configuration diagram of a three-phase rectifier according to an embodiment of the present invention. Since the configuration of the control circuit 3 is different from the configuration of the three-phase rectifier shown in FIG. 12 in the three-phase rectifier of Embodiment 1 shown in FIG. 1, only the configuration of the control circuit 3 will be described. 1 that are the same as those shown in FIG. 12 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The control circuit 3 includes three-phase / two-phase coordinate converters 31, 32, a phase calculator 33, a two-phase / dq coordinate converter 34, adders 30, 35, 37, 39, PI controllers 36, 38, 40, A dq / 2-phase coordinate converter 41 and a spatial voltage vector modulation calculation unit 42 are provided.

  The three-phase / two-phase coordinate converter 31 detects the three-phase AC voltages VSA, VSB, VSC of the UVW three-phase stationary coordinate system of the three-phase AC power source 1, and detects the detected UVW three-phase stationary coordinate system of the three-phase AC power source 1. The three-phase AC voltages VSA, VSB, and VSC are converted into the two-phase AC voltages VSα and VSβ in the αβ orthogonal two-axis stationary coordinate system.

  The three-phase / two-phase coordinate converter 32 converts the three-phase alternating currents IA, IB, IC of the UVW three-phase stationary coordinate system of the three-phase alternating current power supply 1 into the two-phase alternating currents Iα, Iβ of the αβ orthogonal two-axis stationary coordinate system. Convert. The current transformer 4a detects the current IA flowing through the first phase (U phase) of the three-phase AC power supply 1, and the current transformer 4b detects the current IB flowing through the second phase (V phase) of the three-phase AC power supply 1. Then, a current IC that flows through the third phase (W phase) of the three-phase AC power supply 1 is generated from the current −IA and the current −IB by the adder 30.

  The phase calculator 33 corresponds to the phase calculator of the present invention, and obtains the power supply voltage phase θs from the two-phase AC voltages VSα and VSβ converted by the three-phase / two-phase coordinate converter 31. The 2-phase / dq coordinate converter 34 corresponds to the first coordinate conversion means of the present invention, and is converted by the 3-phase / 2-phase coordinate converter 32 based on the power supply voltage phase θs obtained by the phase calculator 33. The two-phase AC currents Iα and Iβ of the αβ orthogonal two-axis stationary coordinate system (corresponding to the first coordinate system of the present invention) are used as the d-axis current Id of the dq orthogonal two-axis rotating coordinate system (corresponding to the second coordinate system of the present invention). , Q-axis current Iq.

  That is, the three-phase / two-phase coordinate converters 31, 32, the phase calculator 33, and the two-phase / dq coordinate converter 34 are current components corresponding to the reactive currents of the three-phase alternating currents lA, IB, IC. The d-axis current Id is converted into a q-axis current Iq which is a current component corresponding to the effective component current.

  The adder 35 is a d-axis current of the dq orthogonal two-axis rotational coordinate system converted by the two-phase / dq coordinate converter 34 from the d-axis current command value (the reactive current command value is 0 (zero)). Id is subtracted and output to the PI controller 36. The PI controller 36 adjusts the output from the adder 35 by proportional integration, and outputs the d-axis voltage command value VRd to the dq / 2-phase coordinate converter 41.

  The adder 37 subtracts the positive voltage (Vp) of the smoothing capacitor C1 from the reference voltage value VRef and outputs the result to the PI controller 38. The PI controller 38 adjusts the output from the adder 37 by proportional integration, and outputs a q-axis current command value IRef to the adder 39. The adder 37 and the PI controller 38 correspond to the current control means of the present invention.

  The adder 39 subtracts the q-axis current Iq of the dq orthogonal two-axis rotational coordinate system converted by the two-phase / dq coordinate converter 34 from the q-axis current command value IRef (effective current command value), and performs PI control. To the device 40. The PI controller 40 adjusts the output from the adder 39 by proportional integration, and outputs the q-axis voltage command value VRq to the dq / 2-phase coordinate converter 41. The adders 35 and 39 and the PI controllers 36 and 40 correspond to the voltage control means of the present invention.

  The dq / 2-phase coordinate converter 41 corresponds to the second coordinate conversion means of the present invention, and is based on the dq orthogonal two axes from the PI controllers 36 and 40 based on the power supply voltage phase θs determined by the phase calculator 33. The d-axis voltage command value VRd and q-axis voltage command value VRq in the rotating coordinate system are converted into the two-phase AC voltages VRα and VRβ (two-phase AC voltage command values) in the αβ orthogonal two-axis stationary coordinate system.

  Each control terminal (gate terminal) of the switching elements Q <b> 1 to Q <b> 6 is connected to the output of the spatial voltage vector modulation calculation unit 42 in the control circuit 3. The spatial voltage vector modulation calculation unit 42 is based on the two-phase AC voltages VRα and VRβ that are voltage command values from the dq / 2-phase coordinate converter 41 and the positive side voltages (Vp, Vo) of the smoothing capacitors C1 and C2. A voltage vector to be executed is selected, and a switching pattern for determining the order of the selected voltage vector is calculated so that the application time of the selected voltage vector and the switching frequency of each switching element Q1 to Q6 are minimized. A command signal to each of the switching elements Q1 to Q6 according to the switching pattern thus generated is generated. In addition, the spatial voltage vector modulation calculating unit 42 switches a maximum of four switching elements among the six switching elements Q1 to Q6 in one carrier, thereby generating a DC output voltage having a stable input power factor and one. obtain.

  Hereinafter, details of the spatial voltage vector modulation calculation unit 42 will be described. FIG. 2 is a voltage vector pattern diagram of the three-level converter unit. FIG. 2 shows switch states and voltage vectors of the six switching elements Q1 to Q6 in the three-level converter unit 2. In FIG. 2, U-axis, V-axis, and W-axis are set every 120 degrees in the counterclockwise direction, and sectors / areas A1 to A4, B1 to B4, C1 to C4, D1 to D4, which are equilateral triangles on a circle, E1 to E4 and F1 to F4 are arranged.

  The apex of the equilateral triangle is marked with a three-letter alpha bed, for example, “PNN”. In “PNN”, P (positive potential) is selected for the U phase in the first phase, N (reference potential) is selected for the V phase in accordance with the selection of ON / OFF of each switching element. The second shows that N is selected in the W phase. In this case, all the switching elements Q1 to Q6 are off, and the path of La → D2 → D1 → C1 → C2 → D8 → D7 → Lb and La → D2 → D1 → C1 → C2 → D12 → D11 → Lc Current flows through the path.

  Depending on the on / off state of the six switching elements Q1 to Q6, there are 12 kinds of states (PNN, PON, PPN, OPN, NPN, NPO, NPP, NOP, NNP, ONP, PNP, PNO at the apex of the outer triangle) ), 12 kinds of states (ONN, POO, OON, PPO, NON, OPO, NOO, OPP, NNO, OOP, ONO, POP) at the vertex of the inner triangle, and 3 kinds (NNN, OOO, PPP) at the origin In total, 27 types of states can be taken.

  FIG. 3 is a diagram showing voltage command vectors and voltage vectors. FIG. 3 shows a case where the sector / region A2 includes a voltage command vector Vref obtained by combining the two-phase AC voltages VRα and VRβ from the dq / 2-phase coordinate converter 41. For example, when all the switching elements Q1 to Q6 are off and the U-phase voltage of the three-phase AC power supply 1 is a positive voltage and the V-phase voltage and the W-phase voltage are negative voltages, the voltage vector is V1 (PNN in FIG. ) At this time, when the V-phase switching elements Q3 and Q4 and the W-phase switching elements Q5 and Q6 are turned on, the voltage vector is V3 (POO) in FIG.

  In the spatial voltage vector modulation method, the voltage command vector is generated from the voltage vector constituting the nearest triangle. In the case of the voltage command vector Vref shown in FIG. 3, the voltage command vector Vref is derived from the three voltage vectors V1 (PNN), V2 (PON), and V3 (POO, ONN) indicated by the sector A2 constituting the nearest triangle. Will be configured.

  FIG. 4 is a diagram showing the relationship between the order of voltage vectors and the number of switching times of the switching elements. In the rightmost column of FIG. 4, the number of switching operations of the switching elements is counted under the condition that all the switching elements Q1 to Q6 are off. As shown in FIG. 4, there are twelve methods for selecting the voltage vectors V1, V2, and V3 and the order of the voltage vectors, and the number of times of switching differs according to these methods.

  In FIG. 4, when the initial value is “PNN”, in Method 2, when the voltage vector is changed in the order of V 1 → V 3 → V 2, N is O in the V phase in V 1 (PNN) → V 3 (POO). , Once in the W phase, N once in the W phase and once in V3 (POO) → V2 (PON), O changes in the W phase once in N, and the number of switching is 3 Times.

  Further, for example, in Method 5, when the voltage vector is changed in the order of V3 → V1 → V2, the initial value is “PNN”. Therefore, in the initial value “PNN” → V3 (POO), the V phase and the W phase are changed. 2 times, V3 (POO) → V1 (PNN), V phase and W phase 2 times, V1 (PNN) → V2 (PON), V phase N is changed to O once, switching times 5 times.

  In the method 1, when the voltage vector is changed in the order of V1 → V2 → V3, in V1 (PNN) → V2 (PON), N is changed to O once in the V phase, and V2 (PON) → V3 (POO). ), N is changed to O in the W phase once, and the number of times of switching is two.

  In the first embodiment, the voltage vector and the order of the voltage vectors in Method 1 that minimizes the number of switching operations are selected. That is, the voltage vector V1 selects PNN, and the voltage vector V3 selects POO. The voltage vector V2 is PON with no room for selection. And a voltage vector is comprised in order of V1-> V2-> V3. With this configuration, the number of times of switching is minimized, switching loss can be reduced, and power supply harmonics can be reduced.

  The voltage vector to be selected and the order of the voltage vectors are updated by calculation every time. Within the same sector / area, one type of voltage vector is selected, but the order of the voltage vectors is two types. For example, in a certain section, the method 1 shown in FIG. 4 (positive order V1 → V2 → V3) is selected, and in the next section, the reverse order V3 → V2 → V1 is selected, and the number of times of switching is selected. It will be the least twice.

  FIG. 5 is a switching pattern showing the selection of the voltage vector in the sector A and its order and application time. FIG. 6 is a switching pattern showing selection of voltage vectors in the sector B, their order, and application time. FIG. 7 is a switching pattern showing the selection of the voltage vector in the sector C and its order and application time. FIG. 8 is a switching pattern showing the selection of the voltage vector in the sector D and its order and application time. FIG. 9 is a switching pattern showing selection of voltage vectors in the sector E and their order and application time. FIG. 10 is a switching pattern showing selection of voltage vectors in the sector F, their order, and application time.

  For example, since the voltage command vector Vref shown in FIG. 3 belongs to the sector A / region 2, the switching pattern shown in FIG. 5B is used. Here, each switching pattern will be described. A right alignment PWM (corresponding to the positive order of voltage vectors) and a left alignment PWM (corresponding to the reverse order of voltage vectors) are provided. T5, T4, and T2 are set, and application times T2, T4, and T5 are set for the left alignment PWM. The sum of the application times T2, T4, and T5 is the half carrier period Tpwm. The total interval of the right alignment PWM interval and the left alignment PWM interval is one carrier cycle.

  The application time T5 corresponds to the voltage vector V1, the application time T4 corresponds to the voltage vector V2, and the application time T2 corresponds to the voltage vector V3. In this switching pattern, only the order of voltage vectors (V1 → V2 → V3) in which the number of times of switching in Method 1 shown in FIG.

  Further, for the switching elements Q1 to Q6, the switching elements indicated by hatching are turned on. In this case, the right-aligned PWM section will be described. In order to generate the voltage vector V1, the switching elements Q1 to Q6 are not turned on during the application time T5. Next, the switching element Q4 is turned on during the application time T4 in order to generate the voltage vector V2.

  Next, in order to generate the voltage vector V3, the switching elements Q4 and Q6 are turned on during the application time T2.

  In this case, V-phase switching element Q4 is switched once at the first timing of application time T4 and W-phase switching element Q6 is switched once at the first timing of application time T2, for a total of two times. The number of times is the smallest.

  As described above, the voltage vector selection shown in FIGS. 5 to 10 and the switching pattern indicating the order thereof are stored in advance in the pattern selection memory 423 (shown in FIG. 11) for all sectors / areas. Thereby, the calculation time required for the selection of the voltage vector and the processing of the order can be shortened.

  FIG. 11 shows a configuration diagram illustrating the function of the spatial voltage vector modulation calculation unit 42 described above. In FIG. 11, the spatial voltage vector modulation calculation unit 42 includes a sector / region determination unit 421, a pattern selection memory 423, an application time calculation unit 425, and a gate command signal generation unit 427.

  The sector / region determination unit 421 determines to which sector / region the two-phase AC voltages VRα and VRβ that are voltage command values from the dq / 2-phase coordinate converter 41 belong. This determines the voltage vector to be selected and the order of the voltage vectors.

  The application time calculation unit 425 calculates the application time of each of the three voltage vectors based on the sector / region result determined by the sector / region determination unit 421 and the two-phase AC voltages VRα and VRβ that are voltage command values. For example, in FIG. 3, the application times T5, T4, and T2 of the voltage vectors V1, V2, and V3 from the α-axis component VRα of the voltage command vector Vref and the β-axis component VRβ obtained by rotating the α-axis by 90 degrees counterclockwise are as follows: It can obtain | require by the relational expression.

VRα = 2 × T5 + T2 + 3 × T4 / 2
VRβ = √3 / 2 × T4
Tpwm = T5 + T2 + T4
By giving VRα, VRβ, and Tpwm to these three equations, T5, T4, and T2 can be obtained by calculation. Here, Tpwm is a pattern calculation cycle for one time.

  When the magnitude (length) of the voltage vector of V3 is 1, the magnitude (length) of the voltage vector of V2 is √3, the α-axis component is 3/2, and the β-axis component is √3 / 2. Thus, the voltage vector of V1 has a magnitude (length) of 2, an α-axis component of 2, and a β-axis component of 0.

  The pattern selection memory 423 performs any switching based on the sector / region result determined by the sector / region determination unit 421, the positive side voltage (Vp) of the smoothing capacitor C1, and the positive side voltage (Vo) of the smoothing capacitor C2. Select a pattern. When there are two types of switching patterns that can be selected, such as the switching patterns of the right alignment PWM and the left alignment PWM shown in FIGS. 5 to 10, the both-ends voltage (Vp−Vo) of the smoothing capacitor C1 and both ends of the smoothing capacitor C2. One of the switching patterns is selected depending on the magnitude relationship with the voltage (Vo).

  The gate command signal generation unit 427 includes switching elements for each phase based on the application time of each of the three voltage vectors calculated by the application time calculation unit 425 and the order of the voltage vectors based on the switching pattern selected by the pattern selection memory 423. The gate command signals Q1 to Q6 are generated.

  As described above, according to the first embodiment of the three-phase rectifier, the spatial voltage vector modulation calculation unit 42 is selected based on the voltage command value from the dq / 2-phase coordinate converter 41 and the voltages of the smoothing capacitors C1 and C2. Since the switching vector which calculates the voltage vector and the switching pattern in which the switching frequency of each of the switching elements Q1 to Q6 becomes the smallest is calculated and the command signal to each switching element is generated, the switching of the switching element is compared with the conventional method. The number of times can be reduced, the switching loss does not increase, the power harmonics can be reduced, and the power factor can be made 1. Further, it can be realized without deteriorating the control performance, the component cost and the size of the apparatus.

It is a circuit block diagram of the three-phase rectifier of embodiment of this invention. It is a voltage vector pattern figure of a 3 level converter part. It is the figure which showed the voltage command vector and the voltage vector. It is a figure which shows the relationship between the order of a voltage vector, and the frequency | count of switching of a switching element. It is a switching pattern which shows selection of the voltage vector in the sector A, its order, and application time. It is a switching pattern which shows selection of the voltage vector in the sector B, its order, and application time. It is a switching pattern which shows selection of the voltage vector in the sector C, its order, and application time. It is a switching pattern which shows selection of the voltage vector in the sector D, its order, and application time. It is a switching pattern which shows selection of the voltage vector in the sector E, its order, and application time. It is a switching pattern which shows selection of the voltage vector in the sector F, its order, and application time. It is a block diagram of a spatial voltage vector modulation calculating part. It is a circuit block diagram of the conventional three-phase rectifier.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3 phase alternating current power supply 2 3 level converter part 3 Control circuit 31,32 3 phase / 2 phase coordinate converter 33 Phase calculator 34 2 phase / dq coordinate converter 30,35,37,39 Adder 36,38,40 PI controller 41 dq / 2-phase coordinate converter 42 Spatial voltage vector modulation calculation unit 421 Sector / region determination unit 423 Pattern selection memory 425 Application time calculation unit 427 Gate command signal generation unit La, Lb, Lc Three-phase AC reactor C1, C2 smoothing capacitor

Claims (3)

A three-phase AC reactor connected in series to a three-phase AC power source;
A three-phase rectifier circuit having a plurality of diodes and a plurality of switching elements, rectifying the three-phase alternating current from the three-phase alternating current reactor and outputting the rectified current to a smoothing capacitor;
Phase calculating means for calculating a power supply voltage phase based on the voltage of the three-phase AC power supply;
First coordinate conversion means for converting the current in the first coordinate system of the three-phase AC power source into the current in the second coordinate system based on the power supply voltage phase from the phase calculation means;
Current control means for generating an effective current command value based on the voltage of the smoothing capacitor and a reference voltage value;
Voltage control means for generating a voltage command value of the second coordinate system based on the current of the second coordinate system from the first coordinate conversion means, the effective current command value and a predetermined reactive current command value; ,
Second coordinate conversion means for converting the voltage command value of the second coordinate system from the voltage control means to a voltage command value of the first coordinate system based on the power supply voltage phase from the phase calculation means;
A voltage vector selected based on the voltage command value of the first coordinate system from the second coordinate conversion means and the voltage of the smoothing capacitor, and a switching pattern in which the switching frequency of each switching element is in the smallest order A spatial voltage vector modulation means for generating a command signal to each of the switching elements;
A three-phase rectifier comprising: The three-phase rectifier circuit corresponds to three sets of four diodes out of twelve diodes, and each set is formed by connecting the first to fourth diodes in series with the same polarity. Two series circuits,
A first circuit is provided corresponding to the three series circuits, and is connected in series between a connection point between the first diode and the second diode and a connection point between the third diode and the fourth diode. Three switching circuits comprising a switching element and a second switching element;
A first smoothing connected between a connection point where the connection points of the first switching element and the second switching element are commonly connected and a connection point where the cathodes at both ends of each of the three series circuits are commonly connected. A capacitor,
A second smoothing connected between a connection point where the connection points of the first switching element and the second switching element are commonly connected and a connection point where the anodes at both ends of each of the three series circuits are commonly connected. And having a capacitor
2. The three-phase rectifier according to claim 1, comprising a three-level converter circuit in which a connection point between the second diode and the third diode is connected to the three-phase AC reactor.   3. The three-phase rectifier according to claim 1, wherein the space voltage vector modulation unit calculates an application time of the selected voltage vector. 4.

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