JP2008086108A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact motor controller in which input voltage rise ratio and efficiency is increased. <P>SOLUTION: The motor controller includes: a rectification circuit 3 that uses an AC power supply 2 as input; a first step-up converter circuit 4 connected to a first transformer 10 connected to the rectification circuit 3 and composed of a first switching means 11 and first and second diodes 12a, 12b; a second step-up converter circuit 5 connected to a second transformer 13 connected to the rectification circuit 3 and composed of a second switching means 14 and third and fourth diodes 15a, 15b; a smoothing capacitor 6 connected to the first and second step-up converter circuits 4, 5; and an inverter circuit 7 that is connected to the smoothing capacitor 6 and drives a motor 8. The operating periods of the first and second step-up converter circuits 4, 5 are made shorter than the period of the AC power supply 2, thereby increasing the operating voltage of the inverter circuit 7, enhancing the efficiency of the motor 8 to save energy, and reducing the price and size of the motor controller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor control device using a converter circuit.

  A full-wave voltage doubler circuit has been used as a circuit for boosting the input voltage of this type of conventional motor control device.

  FIG. 5 is a circuit diagram showing an example of a full-wave voltage doubler circuit of a conventional motor control device.

  In FIG. 5, a full-wave voltage doubler circuit 40 of a conventional motor control device is connected in series between a bridge diode circuit 41 that rectifies the output voltage of the AC power supply 2, and the AC power supply 2 and the bridge diode circuit 41. It has a power factor improving reactor 42, two electrolytic capacitors 43 and 44 connected in series to a bridge diode circuit 41, and an electrolytic capacitor 45 connected in parallel to the electrolytic capacitors 43 and 44. .

  The input terminals 1 a and 1 b of the full wave voltage doubler circuit 40 are connected to the output terminal of the AC power supply 2. The bridge diode circuit 41 includes two diodes 41a and 41b connected in series between the output terminals 1c and 1d of the full-wave voltage doubler circuit 40. A connection point 41c between the diodes 41a and 41b is used for power factor improvement. The reactor 42 is connected to one input terminal 1 a of the full-wave voltage doubler circuit 40 through the reactor 42. The other input terminal 1b of the full wave voltage doubler circuit 40 is connected to a connection point of electrolytic capacitors 43 and 44. Diodes 46 and 47 are connected in parallel to the electrolytic capacitors 43 and 44, respectively. Yes.

  In such a full wave voltage doubler circuit 40, the output voltage of the AC power supply 2 is full wave rectified by the diodes 41 a and 41 b constituting the bridge diode circuit 41, and electrolytic capacitors 43 and 44 are generated by the full wave rectified output of the bridge diode circuit 41. Are alternately charged at the cycle of the output voltage of the AC power supply 2. The voltage doubler of the AC power supply 2 generated at both ends of the capacitors 43 and 44 connected in series by this charging is smoothed by the electrolytic capacitor 45, and is smoothed between the output terminals 1c and 1d of the full-wave voltage doubler circuit 40. Will occur.

  As a method for improving the power factor of the input power source and boosting the input voltage to an arbitrary voltage, a circuit system in which a rectifier circuit includes a booster circuit has been proposed (see, for example, Patent Document 1).

  FIG. 6 is a circuit diagram of a voltage conversion circuit of the conventional motor control device disclosed in Patent Document 1.

  The voltage conversion circuit 50 includes a rectifier circuit 51 that rectifies the output voltage of the AC power supply 2 input to the input terminals 2a and 2b, a boost converter circuit 52 that boosts the output voltage of the rectifier circuit 51, and the boost converter circuit. And an electrolytic capacitor 53 charged by an output voltage of 52.

  The rectifier circuit 51 includes diodes 54 and 55 connected in series and diodes 56 and 57 connected in series. A connection point 50 a between the diodes 54 and 55 is connected to one input terminal 2 a of the voltage conversion circuit 50, and a connection point 50 b between the diodes 56 and 57 is connected to the other input terminal 2 b of the voltage conversion circuit 50. The common connection cathode of the diodes 54 and 56 serves as one output terminal of the rectifier circuit 51, and the common connection anode of the diodes 55 and 57 serves as the other output terminal of the rectifier circuit 51. Yes.

  The boost converter circuit 52 has one end connected to one output terminal of the rectifier circuit 51, an anode connected to the other end of the reactor 58, and a cathode connected to one output terminal 2c of the voltage conversion circuit 50. And a switching means 60 connected between the connection point of the reactor 58 and the diode 59a and the other output terminal of the rectifier circuit 51. Here, the switching means 60 is an IGBT (insulated gate bipolar transistor), and a diode 59b is connected to the switching means 60 in antiparallel.

  In the voltage conversion circuit 50, the AC voltage supplied from the AC power supply 2 is rectified by the rectifier circuit 51, and when the output of the rectifier circuit 51 is input to the boost converter circuit 52, the boost converter circuit 52 includes the rectifier circuit. The output of 51 is boosted by turning on / off the switching means 60. In other words, in the boost converter circuit 52, when the switching means 60 is turned on, the electric circuit on the output side of the reactor 58 is short-circuited, a direct current flows from the rectifier circuit 51 into the reactor 58, and energy is stored in the reactor 58. Thereafter, when the switching means 60 is turned off, an induced voltage is generated in the reactor 58, the capacitor 53 is charged by the sum voltage of the induced voltage and the output of the rectifier circuit 51, and between the terminals of the capacitor 53, the rectifier circuit 51 A voltage higher than the output is generated.

In the voltage conversion circuit 50 having this type of boost capacitor circuit 52, the waveform of the input current from the AC power supply is controlled to be a sine wave by adjusting the time ratio between the ON period and the OFF period of the switching means 60, The power factor can be improved, and the level of the output DC voltage can be controlled by controlling the magnitude (absolute value) of the input current by adjusting the time ratio.
Japanese Patent No. 3308993 (Fig. 1)

  However, the full-wave voltage doubler circuit 40 of the conventional motor control device shown in FIG. 5 requires large-capacitance voltage-doubler capacitors 43 and 44 and a large-capacity power factor improving reactor 42. When the capacity of the capacitor for use is small, the operation as a voltage doubler circuit is not performed.

  The operation of the full wave voltage doubler circuit is such that two capacitors connected in series are alternately charged every half cycle of the input AC voltage, and the sum of the terminal voltages of the two capacitors is output. For this reason, when the capacitance of the capacitor is small, the terminal voltage of the charged capacitor drops during the half cycle of the input voltage where charging is not performed, and is output as the sum of the terminal voltages of the two capacitors. The output voltage of the full wave voltage doubler circuit 40 does not become twice the input voltage.

  Further, in the configuration of the conventional voltage conversion circuit 50 as shown in FIG. 6, for example, it constitutes a motor control device, and depends on the capacity of the reactor 58 constituting the boost converter circuit 52 and the output of the boost converter circuit 52. The capacity of the capacitor 53 to be charged is determined by the switching frequency of the switching means 60. That is, in order to reduce the capacity of the reactor 58, it is necessary to increase the switching frequency so that the harmonic current appearing on the input side can be suppressed. Further, when the capacitance of the capacitor 53 is decreased, the ripple of the voltage charged in the capacitor 53 increases. Therefore, in order to reduce the ripple, it is necessary to increase the switching frequency.

Due to the efficiency of the voltage conversion circuit 50 and the cost of the high-frequency switching element, there is a limit to increasing the actual switching frequency in the boost converter circuit 52. For this reason, the capacities of the reactor 58 and the capacitor 53 must be reduced beyond a certain level. Can not.

  As described above, in the circuit configurations such as the conventional full-wave voltage doubler circuit 40 and the voltage conversion circuit 50 described above, the capacitance of the capacitors and reactors constituting these circuits cannot be reduced more than a certain level. Circuits such as the circuit 40 and the voltage conversion circuit 50 cannot be made small, and there is a problem that it is difficult to reduce the size of a motor control device using such a circuit.

  The present invention solves the above-described conventional problems, and without using a large-capacity capacitor or large-capacity reactor, the step-up rate of the input voltage can be increased more than twice, and the electrical stress of the capacitor can be reduced. An object is to provide a highly efficient and compact motor control device, a compressor, a refrigerator, and an air conditioner.

  In order to solve the above-described conventional problems, a motor control device of the present invention includes a rectifier circuit that receives an AC power supply, a first boost converter circuit, a second boost converter circuit, and the first boost converter. Circuit and a smoothing capacitor connected to the output of the second boost converter circuit, and an inverter circuit connected to the smoothing capacitor and driving the motor, wherein the first boost converter circuit is connected to the output of the rectifier circuit. A primary winding of the first transformer connected; first switching means connected to the primary winding of the first transformer; a first diode; and the output connected to the output of the rectifier circuit. A secondary winding of the first transformer and a second diode connected to the secondary winding of the first transformer, wherein the second boost converter circuit is connected to an output of the rectifier circuit A primary winding of the second transformer, a second switching means connected to the primary winding of the second transformer, a third diode, and the first transformer connected to the output of the rectifier circuit. Operation of the first boost converter circuit and the second boost converter circuit, including a secondary winding of the second transformer and a fourth diode connected to the secondary winding of the second transformer. By making the cycle shorter than the cycle of the AC power supply, the operating voltage of the inverter circuit can be boosted, and the maximum number of revolutions of the motor can be increased. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

  The compressor according to the present invention includes an AC power supply as an input and a motor driven by the motor control device according to any one of claims 1 to 8. The pressure can be increased and the maximum number of rotations of the motor can be increased. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the compressor can be achieved. Further, the price and size of the compressor can be reduced.

  Moreover, the refrigerator of the present invention includes a compressor driven by a motor and the motor control device according to any one of claims 1 to 8, and the motor is driven by the motor control device. The operating voltage of the inverter circuit can be boosted, and the maximum number of revolutions of the motor can be increased. In addition, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the refrigerator can be achieved. Furthermore, the price and size of the refrigerator can be reduced.

Moreover, the air conditioner of this invention is equipped with the compressor driven with a motor, and the motor control apparatus of any one of Claims 1-8, and drives the said motor with the said motor control apparatus. Thus, the operating voltage of the inverter circuit can be boosted, and the maximum number of revolutions of the motor can be increased. In addition, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the air conditioner can be achieved. Further, the reactor can be reduced in size and weight, and the price and size of the air conditioner can be reduced.

  The motor control device of the present invention can continuously increase the input voltage step-up rate to more than double without using a large-capacity capacitor or large-capacity reactor, and can reduce the electrical stress of the capacitor, thereby controlling the motor. The price and size of the apparatus can be reduced.

  Furthermore, since the operating voltage of the inverter circuit can be boosted, the maximum number of revolutions of the motor can be increased and the motor torque can be increased. In addition, when the maximum number of rotations of the motor is determined in advance, it is possible to use a high-efficiency motor with a thin motor winding and an increased number of turns, and energy saving of the motor control device can be achieved.

  According to a first aspect of the present invention, there is provided a rectifier circuit having an AC power supply as an input, a first boost converter circuit, a second boost converter circuit, and outputs of the first boost converter circuit and the second boost converter circuit. A first winding of a first transformer connected to the output of the rectifier circuit, the smoothing capacitor connected and an inverter circuit connected to the smoothing capacitor and driving a motor; First switching means and a first diode connected to a primary winding of the first transformer, a secondary winding of the first transformer connected to an output of the rectifier circuit, A second diode connected to the secondary winding of the first transformer, and the second boost converter circuit includes a primary winding of the second transformer connected to an output of the rectifier circuit, The second A second switching means and a third diode connected to the primary winding of the lance, a secondary winding of the second transformer connected to the output of the rectifier circuit, and 2 of the second transformer. A fourth diode connected to the next winding, wherein the operation cycle of the first boost converter circuit and the second boost converter circuit is shorter than the cycle of the AC power supply, and the operation of the inverter circuit The voltage can be boosted, and the maximum number of rotations of the motor can be increased. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

  In the second invention, in particular, the first transformer and the second transformer of the first invention are configured by a switching transformer, a pulse transformer or a toroidal core, and the operating voltage of the inverter circuit can be boosted. It is possible to increase the maximum number of revolutions of the motor. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

  In the third invention, the first switching means and the second switching means of the first or second invention are constituted by transistors, FETs, IGBTs or photocouplers, and the operating voltage of the inverter circuit is boosted. It is possible to increase the maximum number of rotations of the motor. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

In the fourth invention, in particular, the smoothing capacitor according to any one of the first to third inventions is constituted by an electrolytic capacitor or a film capacitor, and the operating voltage of the inverter circuit can be boosted, and the maximum rotation of the motor The number can be increased. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

  In the fifth invention, in particular, the first boost converter circuit and the second boost converter circuit according to any one of the first to fourth inventions operate in opposite phases, and boost the operating voltage of the inverter circuit. It is possible to increase the maximum number of rotations of the motor. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

  The sixth invention is the first boost converter circuit in which the switch circuit is connected in parallel to the first boost converter circuit of any one of the first to fifth inventions, and the first boost converter circuit is operated when the motor is operated at a low speed. When the boosting operation of the second boost converter circuit is stopped and the switch circuit is turned on, no operation loss occurs in the first and second boost converter circuits, and the motor can be driven efficiently.

  In the seventh invention, in particular, the switch circuit of the sixth invention is constituted by a relay, a transistor, an FET, an IGBT, a bidirectional switch or a photocoupler. It is possible to increase the maximum number of revolutions. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the motor control device can be achieved. Furthermore, the motor control device can be reduced in price and size.

  In the eighth invention, in particular, the first boost converter circuit according to any one of the first to fifth inventions is connected to a fifth diode in parallel. When the motor is operated at a low speed, the first booster circuit is provided. When the boost operation of the converter circuit and the second boost converter circuit is stopped, the operation loss of the first and second boost converters does not occur, and the motor can be driven efficiently.

  A ninth invention includes an AC power supply as an input and a motor driven by the motor control device according to any one of claims 1 to 8, and boosts the operating voltage of the inverter circuit. And the maximum number of rotations of the motor can be increased. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the compressor can be achieved. Further, the price and size of the compressor can be reduced.

  A tenth invention comprises a compressor driven by a motor and the motor control device according to any one of claims 1 to 8, wherein the motor is driven by the motor control device, and an inverter circuit The operating voltage of the motor can be boosted, and the maximum number of revolutions of the motor can be increased. In addition, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the refrigerator can be achieved. Furthermore, the price and size of the refrigerator can be reduced.

  An eleventh invention comprises a compressor driven by a motor and the motor control device according to any one of claims 1 to 8, wherein the motor is driven by the motor control device, and an inverter circuit The operating voltage of the motor can be boosted, and the maximum number of revolutions of the motor can be increased. Further, when the maximum number of rotations of the motor is determined in advance, it is possible to use a motor having higher efficiency than the motor to be used, and energy saving of the air conditioner can be achieved. Furthermore, the reactor can be reduced in size and weight, and the price and size of the air conditioner can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a circuit diagram of a motor control device according to the first embodiment of the present invention, and FIG. 2 is a diagram showing current waveforms and signal waveforms of respective parts of the motor control device.

  1 and 2, the motor control device 1 according to the present embodiment includes an AC power source 2, a rectifier circuit 3 that receives the AC power source 2, and a first transformer 10 that is connected to the output of the rectifier circuit 3. Primary winding 10a, first switching means 11 connected to the primary winding 10a, first diode 12a, and secondary of the first transformer 10 connected to the output of the rectifier circuit 3. A first boost converter circuit 4 having a winding 10b and a second diode 12b connected to the secondary winding 10b of the first transformer 10, and a second connected to the output of the rectifier circuit 3. A primary winding 13a of the transformer 13, a second switching means 14 and a third diode 15a connected to the primary winding 13a, and a second transformer 13 connected to the output of the rectifier circuit 3. Secondary winding 13 And a second boost converter circuit 5 having a fourth diode 15b connected to the secondary winding 13b, and connected to outputs of the first boost converter circuit 4 and the second boost converter circuit 5. Smoothing capacitor 6, an inverter circuit 7 connected to the smoothing capacitor 6 and driving the motor 8, and a motor current of the motor 8 is controlled via the inverter circuit 7 to control the rotation speed of the motor 8. It has the control part 9 to do.

  The primary winding 10a and the secondary winding 10b of the first transformer 10 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite.

  The primary winding 13a and the secondary winding 13b of the second transformer 13 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite.

  The first transformer 10 and the second transformer 13 can be configured with a switching transformer, a pulse transformer, a toroidal core, or the like.

  The first switching means 11 and the second switching means 14 can be composed of transistors, FETs, IGBTs or photocouplers.

  The smoothing capacitor 6 can be composed of an electrolytic capacitor or a film capacitor.

  In the first boost converter circuit 4, the AC voltage supplied from the AC power supply 2 is rectified by the rectifier circuit 3, and the output of the rectifier circuit 3 is input to the first boost converter circuit 4. In the first boost converter circuit 4, the output of the rectifier circuit 3 is boosted by turning on / off the operating cycle of the first switching means 11 in a cycle shorter than the cycle of the AC power supply 2. That is, in the first step-up converter circuit 4, when the first switching unit 11 is turned on, the electric circuit on the output side of the primary winding 10 a of the first transformer 10 is short-circuited, and the primary of the first transformer 10. A direct current flows from the rectifier circuit 3 into the winding 10 a and energy is stored in the primary winding 10 a of the first transformer 10. Thereafter, when the first switching means 11 is turned off, an induced voltage is generated in the primary winding 10a of the first transformer 10, and the smoothing capacitor 6 is charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3. A voltage higher than the output of the rectifier circuit 3 is generated between the terminals of the smoothing capacitor 6.

  Since the primary winding 10a and the secondary winding 10b of the first transformer 10 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite to each other, the first switching means 11 Is turned on, an induced voltage is generated in the secondary winding 10b of the first transformer 10, and the smoothing capacitor 6 is further charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3 through the second diode 12b. Is done.

  In the second boost converter circuit 5, the AC voltage supplied from the AC power supply 2 is rectified by the rectifier circuit 3, and the output of the rectifier circuit 3 is input to the second boost converter circuit 5. In the second boost converter circuit 5, the output of the rectifier circuit 3 is boosted by turning on / off the operation cycle of the second switching means 14 in a cycle shorter than the cycle of the AC power supply 2. The on / off of the second switching means 14 operates in the opposite phase to the on / off of the first switching means 11 of the first boost converter circuit 4.

  That is, in the second step-up converter circuit 5, when the second switching unit 14 is turned on, the electric circuit on the output side of the primary winding 13 a of the second transformer 13 is short-circuited, and the primary winding of the second transformer 13. A direct current flows from the rectifier circuit 3 into the line 13 a and energy is stored in the primary winding 13 a of the second transformer 13. Thereafter, when the second switching means 14 is turned off, an induced voltage is generated in the primary winding 13a of the second transformer 13, and the smoothing capacitor 6 is charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3. A voltage higher than the output of the rectifier circuit 3 is generated between the terminals of the smoothing capacitor 6.

  Since the primary winding 13a and the secondary winding 13b of the second transformer 13 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite to each other, the second switching means 14 Is turned on, an induced voltage is generated in the secondary winding 13b of the second transformer 13, and the smoothing capacitor 6 is further charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3 through the fourth diode 15b. Is done.

  As a result, the first boost converter circuit 4 and the second boost converter circuit 5 alternately perform the boosting operation, so that the boosting rate can be increased more than twice, and the boosting rate can be continuously changed.

  Further, in this embodiment, since a transformer is used in place of the reactor used in the conventional boost converter, energy flowing through the core is also effectively used, so that energy saving can be achieved.

  Furthermore, since the electrical stress applied to the smoothing capacitor 6 can be reduced, the smoothing capacitor 6 can be reduced in size and weight, and low-capacitance switching elements can be used for the first and second switching means 11 and 14, and the motor. The control device can be reduced in price and size.

(Embodiment 2)
FIG. 3 is a circuit diagram of the motor control device according to the second embodiment of the present invention. Note that the same components as those of the motor control device in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In FIG. 3, the motor control device 20 in the present embodiment includes an AC power source 2, a rectifier circuit 3 that receives the AC power source 2, and one of the first transformers 10 connected to the output of the rectifier circuit 3. The secondary winding of the first transformer 10 connected to the output of the secondary winding 10a, the first switching means 11 and the first diode 12a connected to the primary winding 10a, and the rectifier circuit 3. 10b, a first boost converter circuit 4 having a second diode 12b connected to the secondary winding 10b of the first transformer 10, and a second transformer connected to the output of the rectifier circuit 3. 13 primary windings 13 a, second switching means 14 connected to the primary winding 13 a, third diode 15 a, and 2 of the second transformer 13 connected to the output of the rectifier circuit 3. Next winding 13b , A second boost converter circuit 5 having a fourth diode 15b connected to the secondary winding 13b of the second transformer 13, the first boost converter circuit 4, and the second boost converter circuit. The smoothing capacitor 6 connected to the output 5, the inverter circuit 7 connected to the smoothing capacitor 6 and driving the motor 8, and the motor 8 by controlling the motor current of the motor 8 via the inverter circuit 7. It has the control part 9 which controls the rotational speed.

  The primary winding 10a and the secondary winding 10b of the first transformer 10 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite.

  The primary winding 13a and the secondary winding 13b of the second transformer 13 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite.

  Furthermore, the first transformer 10 and the second transformer 13 can be configured by a switching transformer, a pulse transformer, or a toroidal core.

  The first switching means 11 and the second switching means 14 can be composed of transistors, FETs, IGBTs or photocouplers.

  The smoothing capacitor 6 can be composed of an electrolytic capacitor or a film capacitor.

  In the first boost converter circuit 4, the AC voltage supplied from the AC power supply 2 is rectified by the rectifier circuit 3, and the output of the rectifier circuit 3 is input to the first boost converter circuit 4. In the first boost converter circuit 4, the output of the rectifier circuit 3 is boosted by turning on / off the operating cycle of the first switching means 11 in a cycle shorter than the cycle of the AC power supply 2.

  That is, in the first step-up converter circuit 4, when the first switching unit 11 is turned on, the electric circuit on the output side of the primary winding 10 a of the first transformer 10 is short-circuited, and the primary winding of the first transformer 10. A direct current flows from the rectifier circuit 3 into the line 10 a, and energy is stored in the primary winding 10 a of the first transformer 10. Thereafter, when the first switching means 11 is turned off, an induced voltage is generated in the primary winding 10a of the first transformer 10, and the smoothing capacitor 6 is charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3. A voltage higher than the output of the rectifier circuit 3 is generated between the terminals of the smoothing capacitor 6.

  Since the primary winding 10a and the secondary winding 10b of the first transformer 10 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite to each other, the first switching means 11 Is turned on, an induced voltage is generated in the secondary winding 10b of the first transformer 10, and the smoothing capacitor 6 is further charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3 through the second diode 12b. Is done.

  In the second boost converter circuit 5, the AC voltage supplied from the AC power supply 2 is rectified by the rectifier circuit 3, and the output of the rectifier circuit 3 is input to the second boost converter circuit 5. In the second boost converter circuit 5, the output of the rectifier circuit 3 is boosted by turning on / off the operation cycle of the second switching means 14 in a cycle shorter than the cycle of the AC power supply 2. The on / off of the second switching means 14 operates in the opposite phase to the on / off of the first switching means 11 of the first boost converter circuit 4.

  That is, in the second step-up converter circuit 5, when the second switching unit 14 is turned on, the electric circuit on the output side of the primary winding 13 a of the second transformer 13 is short-circuited, and the primary winding of the second transformer 13. A direct current flows from the rectifier circuit 3 into the line 13 a and energy is stored in the primary winding 13 a of the second transformer 13. Thereafter, when the second switching means 14 is turned off, an induced voltage is generated in the primary winding 13a of the second transformer 13, and the smoothing capacitor 6 is charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3. A voltage higher than the output of the rectifier circuit 3 is generated between the terminals of the smoothing capacitor 6.

  Since the primary winding 13a and the secondary winding 13b of the second transformer 13 are connected to the output of the rectifier circuit 3 so that the polarities of the windings are opposite to each other, the second switching means 14 Is turned on, an induced voltage is generated in the secondary winding 13b of the second transformer 13, and the smoothing capacitor 6 is further charged by the sum voltage of the induced voltage and the output of the rectifier circuit 3 through the fourth diode 15b. Is done.

  As a result, the first boost converter circuit 4 and the second boost converter circuit 5 alternately perform the boosting operation, so that the boosting rate can be increased more than twice, and the boosting rate can be continuously changed.

  Further, since a transformer is used instead of the reactor used in the conventional boost converter, the energy flowing through the core is also effectively used, so that energy saving can be achieved.

  Furthermore, since the electrical stress applied to the smoothing capacitor 6 can be reduced, the smoothing capacitor 6 can be reduced in size and weight, and low-capacitance switching elements can be used for the first and second switching means 11 and 14. Therefore, the motor control device can be reduced in price and size.

  In the present embodiment, as shown in FIG. 3, since the switch circuit 21 is provided in parallel with the first boost converter circuit 4, when the motor 8 is operated at a low speed, When the boosting operation of the second boost converter circuit 5 is stopped and the switch circuit 21 is turned on, no operation loss occurs in the first and second boost converter circuits 4 and 5, and the motor 8 can be driven efficiently. it can.

(Embodiment 3)
FIG. 4 is a circuit diagram of a motor control device according to the third embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the component same as the component of the motor control apparatus in the said embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 4, the motor control device 30 in the present embodiment replaces the switch circuit 21 of the motor control device 20 in the second embodiment with a fifth diode 31 as the first boost converter circuit 4. The other configurations and functions are the same as those of the second embodiment.

  With the above configuration, when the boost operation of the first boost converter circuit 4 and the second boost converter circuit 5 is stopped when the motor 8 is operated at a low speed, the operation loss of the first and second boost converters 4 and 5 is reduced. The motor 8 can be driven efficiently without being generated.

  In the first to third embodiments, an example in which two boost converter circuits are connected in parallel has been described. Needless to say, the present invention can also be applied to a form in which three or more boost converter circuits are connected in parallel. No.

  As described above, the motor control device according to the present invention can continuously increase the input voltage step-up rate more than twice without using a large-capacity capacitor or a large-capacity reactor, and the electric stress of the capacitor can be increased. The motor control device can be reduced in price and size. Furthermore, since the operating voltage of the inverter circuit can be boosted, the maximum number of revolutions of the motor can be increased and the motor torque can be increased. In addition, when the maximum number of rotations of the motor is determined in advance, it is possible to use a high-efficiency motor with a thin motor winding and an increased number of turns, which can save energy. It can be widely applied not only to air conditioners but also to various devices using motors.

Circuit diagram of motor control apparatus according to Embodiment 1 of the present invention The figure which shows the current waveform and signal waveform of each part of the motor control device Circuit diagram of motor control apparatus according to Embodiment 2 of the present invention Circuit diagram of motor control apparatus according to Embodiment 3 of the present invention The figure which shows the full wave voltage doubler circuit of the conventional motor control apparatus Circuit diagram of voltage conversion circuit of another conventional motor control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 20, 30 Motor control apparatus 2 AC power supply 3 Rectifier circuit 4 1st step-up converter circuit 5 2nd step-up converter circuit 6 Smoothing capacitor 7 Inverter circuit 8 Motor 9 Control part 10 1st transformer 10a, 13a Primary winding 10b, 13b Secondary winding 11 First switching means 12a First diode 12b Second diode 13 Second transformer 14 Second switching means 15a Third diode 15b Fourth diode 21 Switch circuit 31 5th Diode

Claims (11)

A rectifier circuit that receives an AC power supply, a first boost converter circuit, a second boost converter circuit, a smoothing capacitor connected to the outputs of the first boost converter circuit and the second boost converter circuit, An inverter circuit connected to the smoothing capacitor and driving a motor, wherein the first boost converter circuit includes a primary winding of a first transformer connected to an output of the rectifier circuit, and the first The first switching means and the first diode connected to the primary winding of the transformer, the secondary winding of the first transformer connected to the output of the rectifier circuit, and 2 of the first transformer A second diode connected to a secondary winding, and the second boost converter circuit includes a primary winding of a second transformer connected to an output of the rectifier circuit, and the second transformer. Primary of A second switching means and a third diode connected to the line, a secondary winding of the second transformer connected to the output of the rectifier circuit, and a secondary winding of the second transformer; And a fourth booster circuit, wherein the operation cycle of the first boost converter circuit and the second boost converter circuit is shorter than the cycle of the AC power supply. The motor control device according to claim 1, wherein the first transformer and the second transformer are configured by a switching transformer, a pulse transformer, or a toroidal core. 3. The motor control device according to claim 1, wherein the first switching means and the second switching means are constituted by a transistor, an FET, an IGBT, or a photocoupler. The motor control device according to claim 1, wherein the smoothing capacitor is configured by an electrolytic capacitor or a film capacitor. 5. The motor control device according to claim 1, wherein the first boost converter circuit and the second boost converter circuit operate in opposite phases to each other. The motor control device according to claim 1, wherein a switch circuit is connected in parallel to the first boost converter circuit. The motor control device according to claim 6, wherein the switch circuit includes a relay, a transistor, an FET, an IGBT, a bidirectional switch, or a photocoupler. The motor control device according to claim 1, wherein a fifth diode is connected in parallel to the first boost converter circuit. A compressor having an AC power supply as an input and a motor driven by the motor control device according to any one of claims 1 to 8. A refrigerator comprising a compressor driven by a motor and the motor control device according to any one of claims 1 to 8, wherein the motor is driven by the motor control device. An air conditioner comprising: a compressor driven by a motor; and the motor control device according to any one of claims 1 to 8, wherein the motor is driven by the motor control device.

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