JP2007267566A - Control method and controller of power converter, and controller and system of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the service life of a switch. <P>SOLUTION: After the rotation speed ω rises, when a full-wave rectifying circuit is selected and voltage Va outputted from an inverter reaches an upper limit value Va0 of the voltage Va at the selecting of the full-wave rectifying circuit (after time t1), a current phase β is raised, while the switch S is controlled to on. At time t3, the switch S is switched from on to off. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to control of a power converter, and more particularly to switching of a switch for switching between two types of rectifier circuits.

  The power converter includes a converter that rectifies an input voltage and an inverter that converts the rectified voltage into a certain voltage. The motor can be driven by supplying the voltage output from the inverter to the motor.

  The converter includes a voltage doubler rectifier circuit and a full-wave rectifier circuit, and any one of these is selected to be switchable by a switch. That is, the selected one is connected to the inverter.

  Such control is disclosed in, for example, Patent Document 1 described later. In Patent Document 1, the motor efficiency is improved at low speeds by this control.

  The power converter disclosed in Patent Literature 1 selects a full-wave rectifier circuit when the rotational speed of the motor is smaller than a predetermined value, and a voltage doubler rectifier circuit when the rotational speed is larger than a predetermined value.

JP 61-112575 A

  However, when switching between the full-wave rectifier circuit and the voltage doubler rectifier circuit according to only the rotation speed, there are the following problems. That is, as the load increases, the maximum rotation speed when the full-wave rectifier circuit is selected decreases. For this reason, the predetermined value of the rotation speed serving as a reference for switching must be set to be equal to or lower than the maximum rotation speed at the assumed maximum load. Therefore, when the full-wave rectifier circuit is selected and the load is low, even if the rotational speed does not reach the maximum rotational speed, switching from the full-wave rectifier circuit to the voltage doubler rectifier circuit is executed. It was difficult to increase efficiency.

  In addition, since the switch is switched from the full-wave rectifier circuit to the voltage doubler rectifier circuit before the rotation speed reaches the maximum rotation speed, the number of switching of the switch has increased. When the number of switch switching increases, the switch is likely to be worn, and thus the life of the switch may be shortened.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to extend the life of the switch. Another purpose is to improve efficiency.

  The control method of the power converter according to claim 1 of the present invention includes a pair of input terminals (11a, 11b) to which an AC voltage is supplied, a full-wave rectifier circuit (11) for full-wave rectifying the AC voltage, A voltage doubler rectifier circuit (11) for voltage doubler rectifying the AC voltage, and an output from one of the full wave rectifier circuit and the voltage doubler rectifier circuit are converted into a voltage (Va), and the voltage is converted into a motor (13). An inverter (12) to be supplied to), and a switch (S) capable of selecting which of the full-wave rectifier circuit and the voltage doubler rectifier circuit is connected between the input terminal and the inverter, A method of controlling a power converter (1) capable of executing a flux weakening control on a motor, wherein the switch is not executed until the voltage increases to reach a predetermined value. Select the full-wave rectifier circuit After the voltage reaches the predetermined value, the power converter controls the motor to weaken the magnetic flux while allowing the switch to select the full-wave rectifier circuit, and then the switch performs the voltage doubler rectification. Let the circuit be selected.

  A power converter control method according to a second aspect of the present invention is the power converter control method according to the first aspect, wherein the current flowing through the motor (13) is a phase shift from the q-axis. The weakening magnetic flux control is performed by controlling the phase (β).

  A power converter control method according to a third aspect of the present invention is the power converter control method according to the first aspect, wherein the motor (13) and the inverter (12) obtained when the flux-weakening control is executed. After the efficiency (η) decreases and becomes substantially equal to the efficiency (η0) obtained when the voltage doubler rectifier circuit is selected, the switch (S) is made to select the voltage doubler rectifier circuit.

  A power converter control method according to claim 4 of the present invention is the power converter control method according to claim 3, wherein the current flowing through the motor (13) is a phase shift from the q-axis. The flux weakening control is performed by controlling the phase (β), and the efficiency at the time of execution of the flux weakening control is based only on the current phase or on the basis of the current phase and the rotation speed (ω) of the motor. Desired.

  A power converter control method according to a fifth aspect of the present invention is the power converter control method according to the second or fourth aspect, wherein the current phase (β) is obtained after the flux-weakening control is executed. Is reduced, and the switch (S) is made to select the voltage doubler rectifier circuit.

  A power converter control method according to a sixth aspect of the present invention is the power converter control method according to the fifth aspect, wherein the motor (13) is rotated in parallel with the control for reducing the rotational speed to a predetermined value. Alternatively, after the control is performed, the current phase (β) is decreased.

  A power converter control method according to claim 7 of the present invention is the power converter control method according to claim 6, wherein the rotation is performed even after the switch (S) has selected the voltage doubler rectifier circuit. The speed is maintained at the predetermined value, and then the rotational speed is increased.

  The control method of the power converter according to claim 8 of the present invention includes a pair of input terminals (11a, 11b) to which an AC voltage is supplied, a full-wave rectifier circuit (11) for full-wave rectifying the AC voltage, A voltage doubler rectifier circuit (11) for voltage rectifying the AC voltage, and an output from one of the full-wave rectifier circuit and the voltage doubler rectifier circuit are converted into a voltage, and the voltage is supplied to the motor (13). An inverter (12) for switching, and a switch (S) capable of selecting which of the full-wave rectifier circuit and the voltage doubler rectifier circuit to be connected between the input terminal and the inverter. A method of controlling the power converter (1) capable of performing the flux-weakening control on the other hand, wherein the efficiency (η) of the motor and the inverter is lowered, and the efficiency when the voltage is the same is doubled. Selection of voltage rectifier circuit While the selection time (η1) of the full-wave rectifier circuit is smaller than that, the switch selects the voltage doubler rectifier circuit, the efficiency is further reduced, and the efficiency when the voltage is the same is After the full-wave rectifier circuit is selected more than when the voltage doubler rectifier circuit is selected, the power converter causes the power converter to select the full-wave rectifier circuit and the weak flux with respect to the motor. Execute control.

  A power converter control method according to claim 9 of the present invention is the power converter control method according to claim 8, wherein the current flowing through the motor (13) is a phase shift from the q-axis. The flux weakening control is performed by controlling the phase (β), and the efficiency at the time of execution of the flux weakening control is based only on the current phase or on the basis of the current phase and the rotation speed (ω) of the motor. Desired.

  A power converter control method according to claim 10 of the present invention is the power converter control method according to claim 8 or claim 9, wherein the efficiency decreases when the voltage is the same. When the voltage doubler rectifier circuit and the full-wave rectifier circuit are substantially equal to each other or after that, the rotational speed of the motor is reduced to a predetermined value, and then the full-wave is applied to the switch. The rectifier circuit is selected, and then the rotational speed is maintained for a predetermined period with the predetermined value, and then increased to the rotational speed immediately before the decrease.

  A power converter control method according to an eleventh aspect of the present invention is the power converter control method according to any one of the first to tenth aspects, wherein the motor (13) has a rotor core. In the PM (Permanent Magnet) motor, the rotor core has a reverse saliency.

  A power converter control method according to claim 12 of the present invention is the power converter control method according to claim 11, wherein the q-axis inductance of the rotor core is larger than the d-axis inductance.

  According to a thirteenth aspect of the present invention, a power converter control device executes the power converter control method according to any one of the first to twelfth aspects.

  According to a fourteenth aspect of the present invention, a motor control device includes the control device (2) according to the thirteenth aspect and a power converter (1), and the power converter has a weak magnetic flux with respect to the motor. The control is executable and a pair of input terminals (11a, 11b) to which an AC voltage is supplied, a full-wave rectifier circuit (11) for full-wave rectifying the AC voltage, and a double-voltage rectification of the AC voltage A voltage doubler rectifier circuit (11), an inverter (12) that converts an output from one of the full-wave rectifier circuit and the voltage doubler rectifier circuit into a voltage, and supplies the voltage to the motor (13); A switch (S) capable of selecting which of the full-wave rectifier circuit and the voltage doubler rectifier circuit is connected between the input terminal and the inverter;

  A system according to a fifteenth aspect of the present invention includes the motor control device according to a fourteenth aspect, and the motor (13) controlled by the control device.

  According to the method for controlling a power converter according to the first aspect of the present invention, even if the voltage reaches a predetermined value, the flux weakening control is performed while the full-wave rectifier circuit is selected. The upper limit value of the rotational speed of the motor that can be controlled when selecting is increased. Therefore, the number of times of switching of the switch can be reduced, thereby extending the life of the switch. In addition, after the flux-weakening control is performed, the voltage is switched to the voltage doubler rectifier circuit, so that the voltage supplied to the motor can be increased.

  According to the method for controlling the power converter according to the second aspect of the present invention, the flux weakening control can be executed with high accuracy.

  According to the method for controlling a power converter according to claim 3 of the present invention, the efficiency can be increased.

  According to the method for controlling a power converter according to claim 4 of the present invention, the accuracy of efficiency is good by obtaining the efficiency based on the current phase. Further, by obtaining the efficiency based on the current phase and the rotation speed, the accuracy of the efficiency is further increased. In addition, the efficiency of the motor is increased by switching the switch based on the required efficiency.

  According to the control method of the power converter according to the fifth aspect of the present invention, the control at the time of switching the switch can be stably performed.

  According to the power converter control method of the sixth aspect of the present invention, the counter electromotive force can be reduced by reducing the rotational speed to a predetermined value. Therefore, the current phase can be reduced.

  According to the control method of the power converter according to the seventh aspect of the present invention, the control immediately after the switching of the switch can be stably performed.

  According to the method for controlling a power converter according to claim 8 of the present invention, it is more efficient to perform the control of the full-wave rectifier circuit and the flux-weakening control in parallel than the case of the control by the voltage doubler rectifier circuit. Can be increased.

  According to the method for controlling a power converter according to the ninth aspect of the present invention, the accuracy of the efficiency is good by obtaining the efficiency based on the current phase. Moreover, the accuracy of efficiency further increases by increasing the efficiency based on the current phase and the rotation speed. In addition, the efficiency of the motor is increased by switching the switch based on the required efficiency.

  According to the control method of the power converter of the tenth aspect of the present invention, the control can be stably performed at the time of switching the connection from the voltage doubler rectifier circuit to the full wave rectifier circuit and immediately after that.

  According to the control method of the power converter according to claim 11 or claim 12 of the present invention, the efficiency of the motor and the inverter is increased.

  According to a power converter control device according to a thirteenth aspect of the present invention, a motor control device according to a fourteenth aspect, or a system according to a fifteenth aspect, the control device according to any one of the first to twelfth aspects. The control method can be executed.

  FIG. 1 conceptually shows a system according to the present invention. The system includes a power conversion device and a motor 13. The power conversion device includes a power converter 1 and a control device 2. The output of the power converter 1 is supplied to the motor 13. In FIG. 1, a power source that supplies the AC voltage Vc to the power converter 1 is also shown.

  The power converter 1 includes input terminals 11 a and 11 b, a converter 11, an inverter 12, and a switch S, and can perform a flux-weakening control on the motor 13.

  An AC voltage Vc is applied between the input terminals 11 a and 11 b to supply the AC voltage Vc to the converter 11.

  Converter 11 includes a full-wave rectifier circuit and a voltage doubler rectifier circuit, and is connected between input terminals 11 a and 11 b and inverter 12. The full-wave rectifier circuit full-wave rectifies the AC voltage Vc, and the voltage doubler rectifier circuit double-rectifies the AC voltage Vc.

  The switch S can select which of the full-wave rectifier circuit and the voltage doubler rectifier circuit is connected between the input terminals 11 a and 11 b and the inverter 12. For example, a latch relay is preferably used as the switch S. This is because the power consumed by the switch S is reduced. Further, a latch relay having a relatively short life may be used.

  Specific configurations of the converter 11 and the switch S will be described below.

  Converter 11 includes a bridge diode 111 and capacitors C1 and C2.

  The bridge diode 111 has diodes D1 to D4. The cathode of the diode D1 and the anode of the diode D2 are each connected to the input terminal 11a. The diode D3 has a cathode connected to the input terminal 11b and an anode connected to the anode of the diode D1. The diode D4 has an anode connected to the input terminal 11b and a cathode connected to the cathode of the diode D2.

  Capacitors C1 and C2 are connected in series between the anode of diode D1 and the cathode of diode D2.

  The switch S is connected between a position r1 where the capacitors C1 and C2 are connected to each other and the input terminal 11b.

  Then, by controlling the switch S to be on, the position r1 and the input terminal 11b are short-circuited, so that the converter 11 functions as a full-wave rectifier circuit. On the other hand, by controlling the switch S to be off, the position r1 and the input terminal 11b are opened, so that the converter 11 functions as a voltage doubler rectifier circuit. That is, by switching the switch S, the connection to the voltage doubler rectifier circuit and the connection to the full wave rectifier circuit can be switched to each other. The control of the switch S is performed by the control device 2 as will be described later.

  The output of the converter 11 is supplied to the inverter 12. The inverter 12 converts the output into an AC voltage and supplies the AC voltage to the motor 13. FIG. 1 shows a case where the inverter 12 converts the output of the converter 11 into a three-phase AC voltage and supplies it to the motor 13.

  The control device 2 includes a switch switching unit 21 and a current phase control unit 22. The switch switching unit 21 controls on / off of the switch S.

  The current phase control unit 22 causes the power converter 1 to cause the motor 13 to perform the flux weakening control. Specifically, the current phase β, which is a phase shift from the q-axis of the current flowing through the motor 13, is changed between 0 ° and 90 °. According to such control, the flux-weakening control can be executed with high accuracy.

  Below, control of the power converter by the control apparatus 2 is demonstrated.

First embodiment.
2, (a) current phase β, (b) rotational speed ω of motor 13, (c) DC voltage Vd input to inverter 12, (d) efficiency η of motor 13 and inverter 12, and (e) switch. S switching and (f) the voltage Va output from the inverter 12 are shown.

  At a time t0 when the rotational speed ω is low ((b) in the figure), the switch S is controlled to be turned on by the switch switching unit 21 ((e) in the figure). That is, the full-wave rectifier circuit is selected in the converter 11 ((c) in the figure).

  Then, control for increasing the rotational speed ω is executed from time t0. At this time, the current phase β is controlled to 0 ° by the current phase control unit 22 ((a) in the figure). That is, the power converter 1 does not execute the flux weakening control on the motor 13.

  The rotational speed ω increases, and at time t1, the voltage Va output from the inverter 12 reaches the upper limit value Va0 of the voltage Va when the full-wave rectifier circuit is selected ((f) in the figure). The rotational speed at this time is represented by the symbol ω1 in FIG.

  After the voltage Va reaches the upper limit value Va0, the current phase β is increased by the current phase control unit 22 while the switch S is controlled to be turned on by the switch switching unit 21 ((e) in the figure). a)). That is, the power converter 1 executes the flux weakening control on the motor 13 while the converter 11 selects the full-wave rectifier circuit. By executing the flux weakening control, the rotational speed ω can be further increased from the rotational speed ω1 while maintaining the voltage Va at the upper limit value Va0 (FIGS. (F) and (b) in the figure). However, the efficiency η decreases as the current phase β increases ((d) in the figure). FIG. 2B shows a case where the rotational speed ω is increased to the rotational speed ω2.

  Thereafter, at time t3, the switch S is switched from ON to OFF by the switch switching unit 21 ((e) in the figure). That is, the voltage doubler rectifier circuit is selected in the converter 11 ((c) in the figure).

  According to the control according to the present embodiment, even when the voltage Va reaches the upper limit value Va0, the flux-weakening control is performed with the full-wave rectifier circuit selected, so that the control can be performed when the full-wave rectifier circuit is selected. The upper limit value of the rotational speed ω of the motor 13 can be increased to the rotational speed ω1. Then, even when the motor 13 is driven beyond the rotational speed ω1, the switch S does not have to be switched as long as the rotational speed ω2 is reached. Therefore, the number of times the switch S is switched can be reduced, thereby extending the life of the switch S. In addition, the voltage Va that can be supplied to the motor 13 can be increased because the switching to the voltage doubler rectifier circuit is performed after the flux-weakening control.

  When the flux-weakening control is executed while selecting the full-wave rectifier circuit, the efficiency η decreases because the current phase β increases as the rotational speed ω increases. On the other hand, when the voltage doubler rectifier circuit is selected, the efficiency η decreases because the voltage utilization rate decreases as the rotational speed ω decreases. Therefore, from the viewpoint of increasing the efficiency η, the rotational speed ω2 at which the efficiency η when the flux-weakening control is executed while selecting the full-wave rectifier circuit is substantially equal to the efficiency η when the voltage doubler rectifier circuit is selected. It is desirable to switch the switch S from the full-wave rectifier circuit to the voltage doubler rectifier circuit with (efficiency η0).

  The efficiency η when the flux weakening control is executed while selecting the full-wave rectifier circuit can be obtained based on the current phase β and the rotational speed ω, for example. The efficiency η may be obtained using only the current phase β.

  In the present embodiment, before time t3 when the switch S is switched, the current phase β is controlled to 0 ° at time t2 when the flux weakening control is executed and the rotational speed ω2 is reached. That is, the power converter 1 stops the flux-weakening control that has been performed on the motor 13. According to such control, when the switch S is switched at time t3, the control in the voltage doubler rectifier circuit can be stably performed. It should be noted that the current phase β need not be reduced to 0 ° as long as the control by the voltage doubler rectifier circuit can be performed stably.

  At time t2, the rotational speed ω is decreased to the rotational speed ω3 in parallel with the stop of the flux-weakening control. According to such control, the counter electromotive force can be reduced by reducing the rotational speed ω. Therefore, the current phase β can be reduced. Further, instead of lowering the rotational speed ω, the back electromotive force may be reduced by reducing the load. In the present embodiment, at the time t2, the weakening magnetic flux control is stopped and the rotational speed ω is decreased in parallel. However, the current phase β may be decreased after the rotational speed ω is decreased, for example.

  At time t4 after switching the switch S (after time t3), the rotational speed ω is increased to the rotational speed ω2. In the present embodiment, the rotational speed ω is maintained at the rotational speed ω3 between time t3 and time t4. According to such control, the control immediately after the switch S is switched can be stably performed.

Second embodiment.
3, (a) current phase β, (b) rotational speed ω of motor 13, (c) DC voltage Vd input to inverter 12, (d) efficiency η of motor 13 and inverter 12, and (e) switch. The switching of S is shown respectively.

  At a time t5 when the rotational speed ω is high ((b) in the figure), the switch S is controlled to be turned off by the switch switching unit 21 ((e) in the figure). That is, the voltage doubler rectifier circuit is selected in the converter 11 ((c) in the figure). Then, control for reducing the rotational speed ω is executed from time t5.

  Thereafter, when the rotational speed ω is reduced and the output voltage of the inverter 12 is the same, the efficiency η when the voltage doubler rectifier circuit is selected, and the efficiency η when the flux weakening control is executed while selecting the full-wave rectifier circuit Are switched from the voltage doubler rectifier circuit to the full-wave rectifier circuit at a rotational speed ω4 (efficiency η1) at which they are substantially equal (time t7). Note that the efficiency η when the flux-weakening control is executed while the full-wave rectifier circuit is selected can be obtained based on, for example, the current phase β and the rotational speed ω. The efficiency η may be obtained using only the current phase β.

  After switching the switch S, the current phase β is increased by the current phase control unit 22 (FIG. 5A) while the switch S is controlled to be turned on by the switch switching unit 21 (FIG. 5E). That is, the power converter 1 executes the flux weakening control on the motor 13 while the converter 11 selects the full-wave rectifier circuit.

  Thereafter, if the rotational speed ω decreases to the rotational speed ω1 that can be driven only by the full-wave rectifier circuit without executing the flux-weakening control (time t9), the motor 13 is driven only by the full-wave rectifier circuit. That is, while the full-wave rectifier circuit is selected ((c) in the figure), the weakening magnetic flux control that has been executed is stopped ((a) in the figure).

  According to the control according to the present embodiment, the control of the full-wave rectifier circuit and the flux-weakening control are performed until the control with only the full-wave rectifier circuit (until time t9), compared with the case of the control with the voltage doubler rectifier circuit. The efficiency η can be increased by performing the control using only the full-wave rectifier circuit after performing in parallel.

  In the present embodiment, the efficiency η when the voltage doubler rectifier circuit is selected when the output voltage of the inverter 12 is the same and the efficiency η when the flux weakening control is executed while selecting the full-wave rectifier circuit are substantially equal. At time t6, the rotational speed ω is decreased to the rotational speed ω5, and then the switch S is switched at time t7. Thereafter, the rotational speed ω is maintained until the time t8 while maintaining the rotational speed ω5, and then the rotational speed ω is increased to the rotational speed ω4. According to such control, the control can be stably performed at the time of switching the switch S and immediately after that.

  The controls according to the first and second embodiments are preferably applied when the motor 13 is a PM (Permanent Magnet) motor having a rotor core. In particular, when the rotor core has reverse saliency, for example, when the q-axis inductance is larger than the d-axis inductance, the efficiency of the motor 13 and the inverter 12 can be increased. In the case of a PM motor having reverse saliency, for example, when performing maximum torque control, it is desirable that the steady current phase be a predetermined value other than 0 °.

It is a figure which shows notionally the system concerning this invention. It is a figure which shows control of the power converter demonstrated by 1st Embodiment. It is a figure which shows control of the power converter demonstrated by 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power converter 2 Control apparatus 11 Converter 11a, 11b Input terminal 12 Inverter 13 Motor S switch Va Voltage beta Current phase (eta), (eta) 0, (eta) 1 Efficiency (omega) Rotational speed

Claims (15)

A pair of input terminals (11a, 11b) to which an alternating voltage is supplied;
A full-wave rectification circuit (11) for full-wave rectification of the AC voltage;
A voltage doubler rectifier circuit (11) for voltage rectifying the AC voltage;
An inverter (12) for converting an output from one of the full-wave rectifier circuit and the voltage doubler rectifier circuit into a voltage (Va) and supplying the voltage to the motor (13);
A switch (S) capable of selecting which of the full-wave rectifier circuit and the voltage doubler rectifier circuit is connected between the input terminal and the inverter, and can perform a flux weakening control on the motor. A method for controlling a power converter (1),
Until the voltage increases to a predetermined value, the switch selects the full-wave rectifier circuit without performing the flux-weakening control,
After the voltage reaches the predetermined value, the power converter controls the motor to weaken magnetic flux while allowing the switch to select the full-wave rectifier circuit, and then the switch includes the voltage doubler rectifier circuit. Control method of power converter to be selected.   The method of controlling a power converter according to claim 1, wherein the flux weakening control is performed by controlling a current phase (β) which is a phase shift from a q-axis of a current flowing through the motor (13).   After the efficiency (η) of the motor (13) and the inverter (12) obtained at the time of execution of the flux-weakening control is lowered and becomes substantially equal to the efficiency (η0) obtained at the time of selecting the voltage doubler rectifier circuit The control method of the power converter according to claim 1, wherein the switch (S) selects the voltage doubler rectifier circuit. Performing the flux-weakening control by controlling the current phase (β), which is a phase shift from the q-axis of the current flowing through the motor (13),
The power converter control method according to claim 3, wherein the efficiency at the time of execution of the flux-weakening control is obtained based only on the current phase or based on the current phase and the rotational speed (ω) of the motor.   The method for controlling a power converter according to claim 2 or 4, wherein after the weakening magnetic flux control is executed, the switch (S) is made to select the voltage doubler rectifier circuit after reducing the current phase (β). .   The method of controlling a power converter according to claim 5, wherein the current phase (β) is decreased in parallel with or after the control for reducing the rotational speed of the motor (13) to a predetermined value. .   The method of controlling a power converter according to claim 6, wherein the rotation speed is maintained at the predetermined value even after the switch (S) selects the voltage doubler rectifier circuit, and then the rotation speed is increased. A pair of input terminals (11a, 11b) to which an alternating voltage is supplied;
A full-wave rectification circuit (11) for full-wave rectification of the AC voltage;
A voltage doubler rectifier circuit (11) for voltage rectifying the AC voltage;
An inverter (12) that converts an output from one of the full-wave rectifier circuit and the voltage doubler rectifier circuit into a voltage and supplies the voltage to the motor (13);
A switch (S) capable of selecting which of the full-wave rectifier circuit and the voltage doubler rectifier circuit is connected between the input terminal and the inverter;
A power converter (1) capable of performing flux-weakening control on the motor, comprising:
While the efficiency (η) of the motor and the inverter is reduced, the efficiency when the voltage is the same is smaller when the full-wave rectifier circuit is selected (η1) than when the voltage doubler rectifier circuit is selected. Causes the switch to select the voltage doubler rectifier circuit;
The efficiency is further reduced, and the full-wave rectification is applied to the switch after the efficiency when the voltage is the same is greater when the full-wave rectifier circuit is selected than when the voltage doubler rectifier circuit is selected. A control method for a power converter, wherein the magnetic flux control is performed on the motor by causing the power converter to select a circuit. Performing the flux-weakening control by controlling the current phase (β), which is a phase shift from the q-axis of the current flowing through the motor (13),
The power converter control method according to claim 8, wherein the efficiency at the time of execution of the flux-weakening control is obtained only based on the current phase or based on the current phase and a rotation speed (ω) of the motor. When the efficiency decreases and the efficiency when the voltage is the same is approximately equal when the voltage doubler rectifier circuit is selected and when the full wave rectifier circuit is selected, or after that, the rotation speed of the motor Is reduced to a predetermined value, and then the switch selects the full-wave rectifier circuit,
The method for controlling the power converter according to claim 8 or 9, wherein the rotation speed is increased after maintaining the rotation speed at the predetermined value for a predetermined period. The motor (13) is a PM (Permanent Magnet) motor having a rotor core,
The method of controlling a power converter according to any one of claims 1 to 10, wherein the rotor core has a reverse saliency.   The method of controlling a power converter according to claim 11, wherein the q-axis inductance of the rotor core is larger than the d-axis inductance.   The power converter control apparatus which performs the control method of the power converter as described in any one of Claims 1 thru | or 12. A control device (2) according to claim 13,
A power converter (1),
The power converter is capable of performing flux-weakening control on the motor,
A pair of input terminals (11a, 11b) to which an alternating voltage is supplied;
A full-wave rectification circuit (11) for full-wave rectification of the AC voltage;
A voltage doubler rectifier circuit (11) for voltage rectifying the AC voltage;
An inverter (12) that converts an output from one of the full-wave rectifier circuit and the voltage doubler rectifier circuit into a voltage and supplies the voltage to the motor (13);
A motor control device comprising: a switch (S) capable of selecting which of the full-wave rectifier circuit and the voltage doubler rectifier circuit is connected between the input terminal and the inverter. The motor control device according to claim 14;
The system comprising the motor (13) controlled by the control device.

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