JP4957350B2 - Power conversion device and inverter control device for motor drive using the same - Google Patents

Description

  The present invention relates to a power converter and an inverter controller for driving a motor using the power converter.

  Conventionally, this type of power conversion device has realized a reduction in size, weight, and cost by using a small-capacity reactor and a small-capacity DC link capacitor. Furthermore, the primary side circuit of the switching power supply is configured to charge the primary side capacitor through the unidirectional rectifier from the bus voltage of the inverter, so that the switching power supply can be stabilized even when the DC bus voltage of the inverter has large pulsations. Operation is possible, and power for control and driving can be supplied constantly and stably (for example, Patent Document 1). FIG. 6 shows a conventional power conversion device described in Patent Document 1. In FIG.

  The conventional power converter shown in FIG. 6 includes an AC power source 1, a diode bridge 6 formed of four diodes 2 to 5 for full-wave rectification of AC from the AC power source, and an AC input side of the diode bridge 6. An inserted small-capacity reactor 9, an extremely small-capacity DC link capacitor 7 connected between the DC-side buses of the diode bridge 6, and an inverter 10 for converting the DC power output from the diode bridge 6 into AC power; One end is connected to one of the DC buses of the inverter 10 and the primary circuit of the switching control power supply unit 14 stores the charge, and one end is connected to the other end of the primary capacitor 13 and the other end is the inverter. Unidirectional rectification means 12 connected to the other of the 10 DC buses, and control means 16 to which the output of the switching control power supply unit 14 is supplied Than is.

In such a configuration, a diode or the like is provided between the other end of the primary side capacitor 13 of the switching control power supply unit 14 whose one end is connected to one of the DC buses of the inverter 10 and the other of the DC buses of the inverter 10. By providing the direction rectifying means 12, the primary side capacitor 13 is charged only when the voltage between the DC buses of the inverter 10 is higher than the voltage of the primary side capacitor 13, and the voltage between the DC buses of the inverter 10 is changed to the primary side capacitor. When the voltage is lower than 13, the primary side capacitor 13 does not discharge. Therefore, even if the DC bus voltage of the inverter 10 pulsates greatly, the primary side capacitor 13 that is the input voltage of the switching control power supply unit 14 is used. The switching control power supply unit 14 performs a stable operation without lowering the voltage between both ends to zero, and a constant control power supply and drive Source can be supplied.
JP 2005-253282 A

  However, in the above prior art, when the inverter 10 drives a motor such as a brushless DC motor, when a steep speed fluctuation occurs, regeneration from the motor occurs, and the primary side capacitor via the unidirectional rectifying means 12 is generated. As a result of charging 13, the voltage of the primary side capacitor 13 rises and may exceed the withstand voltage of the components connected to the primary side capacitor 13 and the primary side capacitor 13 such as the switching control power supply unit 14. It had the problem of having sex.

The object of the present invention is to solve the above-mentioned conventional problems, and is a compact, lightweight and low-cost power converter that can ensure stable operation of the switching control power supply even if the DC bus voltage of the inverter pulsates greatly. By improving the reliability of the power conversion device, the utility of the power conversion device shown in the prior art is further enhanced.

In order to achieve the above object, a power converter of the present invention comprises a control means for controlling an inverter, a DC link capacitor provided between the DC buses of the inverter, and one end connected to one of the DC buses of the inverter. A primary-side capacitor, and a switching control power supply unit that is connected to both ends of the primary-side capacitor and receives the voltage across the primary-side capacitor and supplies power to the control means . The switch means that closes when the voltage exceeds a predetermined voltage is connected in parallel with the unidirectional rectifying means.

  As a result, it is possible to prevent the primary side capacitor voltage from rising beyond the withstand voltage of the primary side capacitor itself and the withstand voltage of the components such as the switching control power supply connected to the primary side capacitor. Even if the DC bus voltage of the inverter pulsates greatly, the converter can ensure stable operation of the switching control power supply, improve the reliability of the power converter, and increase the practicality of the power converter shown in the prior art. .

  The motor drive device of the present invention can realize a stable operation of the switching control power supply unit even if the DC link capacitor of the inverter has a very small capacity, and the dc bus voltage of the inverter pulsates greatly, and a rapid fluctuation of the motor speed By protecting the switching control power supply unit from the regenerative voltage associated with, the reliability of the device is remarkably improved.

The invention of the power conversion device according to claim 1 of the present invention includes a rectifier circuit including an AC power supply as an input and a diode bridge and a reactor connected to an AC input side or a DC output side of the diode bridge; An inverter that converts direct current power, which is the output of the rectifier circuit, into alternating current power, control means for controlling the inverter, a DC link capacitor provided between the direct current buses of the inverter, and one end of one of the direct current buses of the inverter and connected primary side capacitor, connected across the primary-side capacitor, an input voltage of both ends of the primary-side capacitor, and the switching control power source for supplying power to said control means, one end of the Unidirectional rectifying means connected to the other end of the primary capacitor and connected to the other of the DC buses of the inverter; Switch means connected in parallel with the means and closing when the voltage of the primary side capacitor becomes a predetermined voltage or higher, so that the charge accumulated in the primary side capacitor can be supplied to the load side. ing. As a result, when charge is accumulated in the primary side capacitor higher than usual due to regeneration or the like, this charge is used to drive the load and the primary side capacitor voltage is lowered, so that the reliability of the device is improved. Can do.

  In addition to the invention of claim 1, the invention of the power conversion device of claim 2 includes a voltage detection means for detecting the voltage of the primary side capacitor, and a voltage detected by the voltage detection means. Switch control means for opening and closing the switch means when the voltage exceeds a predetermined voltage, and when the primary capacitor voltage rises to a predetermined potential, the switch means is turned on. The rise in the capacitor voltage can be accurately detected, the rise in the voltage can be reliably prevented, and the reliability can be further improved.

  According to a third aspect of the present invention, there is provided a power conversion device according to the first or second aspect, wherein the unidirectional rectifying means and the switch means are combined into a single package. Therefore, it is possible to reduce the number of manufacturing steps and improve the reliability by reducing the number of parts.

  According to a fourth aspect of the present invention, there is provided the power conversion device according to the first aspect, wherein when the switch means becomes a preset voltage of the primary side capacitor voltage, It was made to become. This eliminates the need for voltage detection means for the primary capacitor and switch control means for controlling on / off of the switch, and simplification of the algorithm and further reduction in size and cost can be realized by reducing the number of parts. .

  Further, the invention of the inverter control device for driving a motor according to claim 5 has the power conversion device according to any one of claims 1 to 4, and is small, light weight, low cost, and high. Reliability can be realized.

  According to a sixth aspect of the present invention, there is provided a motor drive inverter control apparatus, wherein the motor drive inverter drives a motor of a compressor of a refrigerating and air-conditioning cycle. An inverter control device for driving the machine motor can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but detailed description of the same configurations as those of the conventional examples or the embodiments described above will be omitted. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 is a block diagram of a power conversion apparatus according to Embodiment 1 of the present invention.

  The power conversion device according to the present embodiment includes an AC power source 1, a diode bridge 6 formed by four diodes 2 to 5 for full-wave rectification of AC from the AC power source, and an AC input side of the diode bridge 6. A small-capacity reactor 9, a very small-capacity DC link capacitor 7 connected between the DC-side buses of the diode bridge 6, an inverter 10 for converting DC power output from the diode bridge 6 into AC power, and one end Is connected to one of the DC buses of the inverter 10, the primary circuit of the switching control power supply unit 14 stores the charge, and one end is connected to the other end of the primary capacitor 13 and the other end is connected to the inverter 10. Unidirectional rectifying means 12 connected to the other DC bus, control means 16 to which the output of the switching control power supply unit 14 is supplied, and unidirectional regulation. The switch means 19 connected in parallel with the means 12 and closed when the voltage of the primary side capacitor 13 exceeds a predetermined voltage, the voltage detection means 17 for detecting the voltage of the primary side capacitor 13, and the voltage detection means 17 And a switch control means 18 for closing the switch means 19 from the open state when the voltage detected in (1) exceeds a predetermined voltage.

  The control means 16 for controlling the inverter 10 is supplied with electric power from the switching control power supply unit 14, and the switching control power supply unit 14 is connected to both ends of the primary capacitor 13. The primary capacitor 13 is connected in series with the unidirectional rectifier 12, and the primary capacitor 13 and the unidirectional rectifier 12 connected in series are connected in parallel with the diode bridge 6.

  The voltage detection means 17 detects the voltage across the primary side capacitor 13 of the switching control power supply unit 14, and the switch control means 18 turns on / off the switch means 19 connected in parallel with the unidirectional rectification means 12. It is something to control.

  In the present embodiment, the output of the inverter 10 (power converter) drives the motor 20, and the motor 20 includes a three-phase star-connected winding stator and a rotor having a permanent magnet. It has a brushless DC motor.

In addition, the winding method of the stator winding may be concentrated winding or distributed winding. Further, the arrangement method of the permanent magnet of the rotor may be a surface magnet type (SPM) or a magnet embedded type (IPM), and may be a ferrite magnet or a rare earth magnet.

  By using a rare earth magnet as the permanent magnet, the motor efficiency can be improved when using the same magnet weight as that of the ferrite magnet, and a motor having the same performance as a motor using a ferrite magnet can be used. In this case, the weight of the motor can be reduced because the magnet weight can be reduced.

  Further, in the present embodiment, the motor 20 drives the compressor 22 of the refrigeration and air conditioning system, and the compression element 21 is connected to the rotor shaft of the motor 20 and sucks, compresses and discharges the refrigerant gas. The motor 20 and the compression element 21 are housed in the same hermetic container to constitute the compressor 22.

  The discharge gas compressed by the compressor 22 constitutes a refrigeration air conditioning system that returns to the suction of the compressor 22 through the condenser 23, the decompressor 24, and the evaporator 25. Then, since endotherm is performed, cooling and heating can be performed. In addition, a heat exchanger may be further accelerated | stimulated using a fan etc. for the condenser 23 and the evaporator 25 as needed.

  In this embodiment, an FET is used as an element constituting the inverter 10, but an IGBT or a bipolar transistor may be used.

  About the power converter device comprised as mentioned above, the operation | movement is demonstrated using FIG.1, FIG.2 and FIG.3.

  FIG. 2 is a timing chart showing the operation of the switch means in the same embodiment. The line (a) in FIG. 2 shows the state of the voltage across the primary capacitor, and the line (b) in FIG. Indicates an on / off state. FIG. 3 shows an operation flowchart in the embodiment.

  In FIG. 3, in Step 101, the voltage detection means 17 detects the voltage level of the primary side capacitor 13 in real time to check whether it is higher or lower than a predetermined potential (for example, 200V). In the normal state (section a), the potential across the primary capacitor 13 is about the peak value of the commercial power supply (140V in the case of AC100V), so the switch control means 18 in Step 101 causes the switch means 19 to This operation is repeated after that.

  Next, the case where the speed variation of the motor 20 occurs (section b) will be described. Due to the occurrence of regeneration due to the speed fluctuation of the motor 20, the voltage of the primary side capacitor 13 also starts to rise as the inverter bus voltage rises. Here, when the voltage of the capacitor 13 on the primary side reaches a predetermined potential (for example, 200 V), the process proceeds to Step 103, where the switch control means 18 turns on the switch means 19 and the potential of the capacitor 13 on the primary side is predetermined. This operation is repeated until the potential drops to.

  As a result, the outflow of the charge of the primary side capacitor 13 to the inverter 10 side is blocked by the unidirectional rectifying means 12, but the DC bus of the inverter 10 and the positive side of the primary side capacitor 13 are short-circuited. The accumulated charge in the secondary capacitor is consumed by driving the load by the inverter, and the potential of the primary capacitor 13 is lowered.

Further, when the voltage of the primary side capacitor 13 returns to a predetermined potential, the process proceeds from Step 101 to Step 102, the switch means 19 is turned off, and this operation is repeated (section d).

  In this way, the potential of the primary side capacitor 13 is monitored, and when the potential rises to a predetermined level, the switch means 19 is turned on to drive the load higher than normal stored in the primary side capacitor 13 to the load. By using the power consumption for the first time, the abnormal voltage rise of the primary side capacitor 13 is prevented, and the breakdown voltage of the parts connected to the primary side capacitor 13 itself and the primary side capacitor 13 is always lower than the breakdown voltage of the parts. Failure is prevented and the reliability of the equipment is improved.

  Furthermore, when the motor 20 has a large current, when the motor 20 is driven at a high speed, and when the rotor of the motor 20 has a rare earth magnet with a strong magnetic force, the regenerative energy of the motor 20 increases, so that In the technology, in order to keep the regenerative energy below the breakdown voltage of the component, the circuit size is increased as the capacity of the primary capacitor 13 is increased. However, in this embodiment, the minimum required capacitor capacity is sufficient, and the circuit size is increased. Can be suppressed.

  As described above, the power conversion device according to the present embodiment includes the rectifier circuit including the diode bridge 6 and the reactor 9 connected to the AC input side of the diode bridge 6 with the AC power supply 1 as an input, and the rectifier circuit. Of the inverter 10 for converting the direct current power to the alternating current power, the DC link capacitor 7 provided between the direct current buses of the inverter 10, and the switching control power supply unit 14 having one end connected to one of the direct current buses of the inverter 10. Primary capacitor 13, unidirectional rectifier 12 having one end connected to the other end of primary capacitor 13 and the other end connected to the other DC bus of inverter 10, and connected in parallel to unidirectional rectifier 12 And switch means 19 that closes when the voltage of the primary side capacitor 13 becomes equal to or higher than a predetermined voltage. Can be supplied to the load side, so that when the electric charge is accumulated in the primary side capacitor 13 higher than usual and the voltage of the primary side capacitor 13 rises abnormally due to regeneration or the like, the load is driven. Since the voltage of the primary side capacitor 13 can be lowered by using this charge, the reliability of the device can be improved and the voltage of the primary side capacitor 13 can be set to the minimum necessary capacity. Cost reduction can be realized.

  Further, voltage detecting means 17 for detecting the voltage of the primary side capacitor 13 and switch control means 18 for closing the switch means 19 from open to closed when the voltage detected by the voltage detecting means 17 exceeds a predetermined voltage. And the voltage detection means 17 detects the voltage of the primary side capacitor 13 and turns on the switch means 19 when the voltage of the primary side capacitor 13 rises to a predetermined potential. The rise can be accurately detected, the rise in voltage can be reliably prevented, and the reliability can be further improved.

  In the present embodiment, since the inverter control device for motor drive is configured by the power conversion device of the present embodiment, the motor drive inverter control device can be realized in a small size, light weight, low cost, and high reliability. Can do.

  Moreover, the inverter for motor drive of this Embodiment drives the motor of the compressor of a refrigerating / air-conditioning cycle, and can provide the inverter control apparatus which drives the compressor motor which has the said effect.

(Embodiment 2)
FIG. 4 is a block diagram of the power conversion device according to Embodiment 2 of the present invention. In FIG. 4, the rectifying / switching means 26 is an element having a composite function that serves as both the unidirectional rectifying means 12 and the switching means 19 in the first embodiment, and is housed in one package. In this embodiment, an FET is used, and a parasitic diode between the drain and source plays a role as a unidirectional rectifier.

  As described above, according to the second embodiment, the unidirectional rectification unit and the switch unit are the components (rectification / switch unit 26) housed in one package, thereby further reducing the size of the power conversion device. Cost reduction and reliability can be improved by reducing man-hours for component mounting.

  Note that an IGBT is used as the rectifying / switching means 26 (in this case, a diode is required between the collector and the emitter as the unidirectional rectifying means, but an FRD is generally inserted between the collector and the emitter of the power circuit IGBT. In many cases, it is enclosed in one package, and it may be used as one component as in the case of FET).

  As described above, in the second embodiment, the unidirectional rectification means and the switch means are configured by a single component (rectification / switch means 26) contained in one package, thereby further reducing the size of the power conversion device. Can be realized, and cost reduction and reliability can be improved by reducing man-hours for component mounting.

(Embodiment 3)
FIG. 5 is a block diagram of a power conversion device according to Embodiment 3 of the present invention. In the present embodiment, the switch means 27 is a rectifier diode and a Zener diode that are connected in series on the anode side. When the voltage of the primary side capacitor 13 becomes a preset voltage, the switch means 27 is turned on by itself. It is trying to be in a state.

  As a result, the primary-side capacitor voltage that is rendered conductive by selecting the Zener diode can be set, and the on / off timing is controlled by itself. Therefore, the voltage detection means 17 and the switch control means of the primary-side capacitor 13 in the first embodiment. No. 18 is not necessary, and the control algorithm can be simplified and the power converter can be further reduced in size and cost associated with the reduction in the number of parts.

  As a result, when the voltage of the capacitor is increased, the conductive state is established, so that an abnormal voltage increase of the capacitor can be avoided.

  The power conversion device of the present invention can prevent the primary side capacitor voltage from rising beyond the withstand voltage of the primary side capacitor itself and the withstand voltage of components such as the switching control power supply connected to the primary side capacitor. A lightweight, low-cost power converter that ensures stable operation of the switching control power supply even if the DC bus voltage of the inverter pulsates greatly, improving the reliability of the power converter and increasing the degree of freedom in product design. Since low-priced products can be provided, the present invention can be applied to motor-driven inverter control devices that drive motors using inverter circuits such as air conditioners, refrigerators, washing machines, dishwashers, vacuum cleaners, and blowers.

The block diagram of the power converter device in Embodiment 1 of this invention Timing chart showing operation of switch means in Embodiment 1 of the present invention The flowchart which shows the operation | movement in Embodiment 1 of this invention. The block diagram of the power converter device in Embodiment 2 of this invention The block diagram of the power converter device in Embodiment 3 of this invention Block diagram of a conventional power converter

DESCRIPTION OF SYMBOLS 1 AC power supply 6 Diode bridge 7 DC link capacitor 9 Reactor 10 Inverter 12 Unidirectional rectification means 13 Primary side capacitor 14 Switching control power supply part 17 Voltage detection means 18 Switch control means 19 Switch means 22 Compressor 26 Rectification / switch means 27 Switch means

Claims (6)

A rectifier circuit comprising an AC power supply as an input and a diode bridge and a reactor connected to an AC input side or a DC output side of the diode bridge; an inverter for converting DC power, which is an output of the rectifier circuit, into AC power; A control means for controlling the inverter, a DC link capacitor provided between the DC buses of the inverter, a primary capacitor having one end connected to one of the DC buses of the inverter, and both ends of the primary capacitor A switching control power supply unit that inputs the voltage across the primary capacitor and supplies power to the control means; one end connected to the other end of the primary capacitor and the other end of the inverter A unidirectional rectifier connected to the other of the DC buses, and an electric power supply of the primary capacitor connected in parallel with the unidirectional rectifier There power conversion apparatus characterized by a switch means for closing when it is higher than a predetermined voltage. 2. A voltage detection means for detecting the voltage of the primary side capacitor, and a switch control means for closing the switch means from open to closed when the voltage detected by the voltage detection means exceeds a predetermined voltage. The power converter device described in 1. The power converter according to claim 1 or 2, wherein the unidirectional rectifying means and the switch means are a single component placed in one package. 2. The power conversion device according to claim 1, wherein when the primary side capacitor voltage becomes a preset voltage, the switch unit is in a conductive state by itself. The inverter control apparatus for motor drive using the power converter device as described in any one of Claims 1-4. The inverter control apparatus for motor drive according to claim 5 which drives a compressor of a refrigeration air-conditioning cycle.

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