JP5724451B2 - Power supply device and air conditioner - Google Patents

Description

  The present invention relates to prevention of inrush current in a power supply device.

  In a power supply for driving a compressor of a conventional air conditioner, it is energized through an inrush current prevention resistor to prevent destruction of elements such as a diode bridge due to an inrush current flowing when charging an electrolytic capacitor when the power is turned on. ing. This inrush prevention resistor is charged in the capacitor after a certain time, and when a large current stops flowing, the mechanical relay, which is a bidirectional switch, is switched to disconnect the resistor (see, for example, Patent Document 1).

JP 2008-252966 A (columns 0017, 0025, FIG. 1)

  The conventional air conditioner has a configuration in which a mechanical relay is made non-conductive to flow current through an inrush current prevention resistor and then the mechanical relay is made conductive again in response to an instantaneous power failure such as a momentary power interruption. Depending on the timing when the mechanical relay is turned on, the electrolytic capacitor is not sufficiently charged, and there is a problem that an inrush current flows to an element such as a diode bridge through the mechanical relay.

  An object of the present invention is to provide a power supply apparatus that can prevent an inrush current from flowing through an element such as a diode bridge when an external AC power supply is momentarily cut off.

  The power supply device of the present invention includes a rectifier circuit that rectifies an alternating current supplied from an alternating current power supply, phase detection means that detects a phase of an alternating voltage applied from the alternating current power supply to the rectifier circuit, the alternating current power supply, and the A bidirectional switch provided between the rectifier circuits, capable of energizing bidirectionally from the AC power source to the rectifier circuit and from the rectifier circuit to the AC power source, a resistor provided in parallel with the bidirectional switch, and the rectifier A smoothing capacitor that smoothes the current rectified by the circuit and supplies it to the load side, whether or not the alternating current is stopped based on the phase detected by the phase detection means, and whether or not the alternating current is restarted Determining means for determining whether or not the bidirectional switch is turned off when the determining means determines that energization of the alternating current is stopped, and the determining means is configured to pass the alternating current. But and a control means for controlling said bidirectional switch near zero cross of the AC voltage detected by said phase detecting means and determines that resume is turned on.

  A rectifying circuit for rectifying an alternating current supplied from the alternating current power supply; a phase detecting means for detecting a phase of the alternating voltage flowing from the alternating current power supply to the rectifying circuit; and a load obtained by smoothing the current rectified by the rectifying circuit. A smoothing capacitor to be supplied to the side, a P-type MOSFET element provided on a high voltage side wiring connecting the rectifier circuit and the load side, a source connected to the rectifier side and a drain connected to the load side, and the phase detection Determining means for determining whether or not the supply of the alternating current has been stopped based on the phase detected by the means and whether or not the supply of the alternating current has been resumed; and the determination means has stopped supplying the alternating current If the determination means determines that the MOSFET element is turned off, and the determination means determines that energization of the alternating current has been resumed, the AC voltage detected by the phase detection means is zero. It said MOSFET device in loss near and control means for controlling the turn on.

  A rectifying circuit for rectifying an alternating current supplied from an alternating current power supply; a phase detecting means for detecting a phase of the alternating current flowing from the alternating current power supply to the rectifying circuit; and a current rectified by the rectifying circuit is smoothed. A smoothing capacitor to be supplied to the load side, an N-type MOSFET element provided on a low-voltage side wiring connecting the rectifier circuit and the load side, a source connected to the rectifier side and a drain connected to the load side, and the phase Based on the phase detected by the detection means, determination means for determining whether the supply of the alternating current is stopped and whether the supply of the alternating current is restarted, and the determination means stops the supply of the alternating current If it is determined that the MOSFET element is turned off, the AC voltage detected by the phase detection unit is detected when the determination unit determines that the energization of the AC current is resumed. It said MOSFET device in Rokurosu vicinity and control means for controlling the turn on.

  An air conditioner according to the present invention includes any one of the power supply devices described above, an inverter that converts a direct current converted by the power supply device into an alternating current, and a motor that is driven by the alternating current converted by the inverter. Prepare.

  In the present invention, both switches or MOSFET elements are turned off until AC voltage zero crossing is detected even after the AC power supply recovers, so that an inrush current flows to an element such as a rectifier circuit when the AC power supply recovers. Can be prevented.

1 is a circuit diagram of a power supply device 100 according to a first embodiment of the present invention. The figure which shows the ON / OFF timing of the bidirectional | two-way switch 10 at the time of the momentary power failure of AC power supply 1 of Embodiment 1 of the present invention. 1 is a configuration diagram of a bidirectional switch 10 according to a first embodiment of the present invention. Another block diagram of bidirectional switch 10 of Embodiment 1 of the present invention. The figure which shows switching of the bidirectional | two-way switch 10 at the time of the power recovery of Embodiment 1 of this invention. The flowchart figure which shows the control method of the power supply device 100 of Embodiment 1 of this invention. The circuit diagram of the power supply device 110 of Embodiment 2 of this invention. The circuit diagram of the power supply device 120 of Embodiment 2 of this invention. The block diagram of the air conditioning apparatus 200 of Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 shows a configuration diagram of a power supply device 100 according to the first embodiment. The power supply device 100 described in the first embodiment is used as a power source for driving, for example, a motor built in a compressor of an air conditioner or a motor of a blower fan.
The power supply device 100 includes an inrush current prevention circuit 2 that prevents an inrush current from an AC power source 1 that is an external power source, a rectifier circuit 3 that rectifies an AC current supplied from the AC power source 1, and a current rectified by the rectifier circuit 3. The step-up chopper circuit 4 is provided for boosting and converting to DC current.
A high voltage side bus 5 is connected to the output terminal of the rectifier circuit 3 on the high voltage side, and a low voltage side bus 6 is connected to the output terminal on the low voltage side. The rectifier circuit 3 and the step-up chopper circuit 4 are converter units that convert alternating current into direct current. The current converted into direct current is supplied from the step-up chopper circuit 4 to the inverter 7 on the load side, and the direct current is converted into the inverter 7. Is converted into a three-phase alternating current of any frequency. The current converted from the direct current to the three-phase alternating current by the inverter 7 flows to the motor 8 connected to the inverter 7 to drive the motor 8. The motor 8 is, for example, a compressor of an air conditioner or a blower fan motor.

The inrush current prevention circuit 2 includes a resistor 9 and a bidirectional switch 10. The resistor 9 and the bidirectional switch 10 are connected in parallel. When the bidirectional switch 10 is on-controlled and an alternating current is conducted through the bidirectional switch 10, almost all current flows through the bidirectional switch 10. When the bidirectional switch 10 is off-controlled and non-conductive, all current flows through the resistor 9.
The bidirectional switch 10 includes a switching element, and the switching element is turned on / off to switch between conduction / non-conduction of alternating current between the power supply side contact 11 and the rectifier circuit side contact 12. . A specific configuration of the bidirectional switch 10 will be described later with reference to FIGS.

  The rectifier circuit 3 is a diode bridge in which, for example, four diodes are provided in a bridge shape, and rectifies an alternating current flowing from the alternating current power supply 1 and supplies it to the load side.

The step-up chopper circuit 4 includes a coil 13, a switching element 14, a diode 15, and a smoothing capacitor 16. The coil 13 is connected in series with the output terminal on the high voltage side of the rectifier circuit 3 on the high voltage side bus 5 on the high voltage side of the rectifier circuit 3, and a diode 15 is provided in series with the coil 13. The diode 15 has an anode connected to the coil 13 and a cathode connected to the inverter 7. A switching element 14 is provided on the wiring connecting the high voltage side bus 5 to the low voltage side bus 6 between the coil 13 and the diode 15. The switching element 14 is, for example, an IGBT (Insulated Gate Bipolar Transistor). The smoothing capacitor 16 is provided on the wiring connecting the high voltage side bus 5 to the low voltage side bus 6 between the diode 15 and the inverter 7. The low-voltage bus 6 is grounded and has a ground potential.
In the step-up chopper circuit 4, the coil 13 accumulates energy while the switching element 14 is on, and the smoothing capacitor 16 is connected via the diode 15 using the back electromotive force generated from the coil 13 when the switching element 14 is off. To charge. The AC current supplied from the AC power source 1 flows into the inverter 7 as a DC current boosted and smoothed by the rectifier circuit 3 and the boost chopper circuit 4.

  The power supply device 100 includes a phase detection unit 17 that detects the phase of the AC voltage applied from the AC power source 1 to the rectifier circuit 3 and whether AC current is supplied from the AC power source 1 based on the phase detected by the phase detection unit 17. Determination results of the energization / power failure determination means 18 for determining whether a power failure has occurred, the voltage detection means 20 for detecting the voltage across the smoothing capacitor 16, that is, the potential difference between the high-voltage side bus 5 and the low-voltage side bus 6, and the energization / power failure determination means 18 Alternatively, a control means 19 for controlling the bidirectional switch 10, the switching element 14, and the inverter 7 from the detection value of the voltage detection means 20 is provided, and the bidirectional switch 10 is turned on / off based on a control signal output from the control means 19. A drive circuit 21 for driving off and a drive circuit 22 for driving on / off of the switching element 14 are also provided.

The phase detection unit 17 detects a potential difference between the positive side and the negative side of the AC power supply 1 and outputs the detected value to the energization / power failure determination unit 18. Furthermore, the phase detection means 17 detects the moment when the potential difference (AC voltage value) becomes zero when the potential difference changes from positive to negative or from negative to positive as a zero cross.
The energization / power failure determination unit 18 performs the following three pattern determinations based on the detection value input from the phase detection unit 17 and outputs the determination result to the control unit 19.
(1) Whether the AC power supply 1 has failed.
(2) Whether energization of the alternating current flowing from the alternating current power source 1 to the rectifier circuit 3 is resumed.
(3) Whether or not the AC voltage value of the AC power source 1 has crossed zero.
The control means 19 performs drive control of the bidirectional switch 10 based on the determination result input from the energization / power failure determination means 18. Details of the control method of the control means 19 will be described later with reference to FIG.

  A determination method performed by the energization / power failure determination means 18 will be described with reference to FIG. 2A shows the relationship between the time t and the AC voltage V in FIG. 2A in the upper stage, and FIG. 2B shows the relationship between the time t and the ON / OFF timing of the bidirectional switch 10 in the lower stage. 2A, the horizontal axis represents time t, and the vertical axis represents the voltage V of the AC voltage applied by the AC power source 1 to the rectifier circuit 3. In FIG. 2B, the horizontal axis represents time t and the vertical axis represents bidirectional. The on / off state of the switch 10 is shown. In FIG. 2, the power supply from the AC power supply 1 is stopped due to a power failure at time t = t1, the AC power supply 1 is restored at time t = t2, and the power supply from the AC power supply 1 is resumed. To do. At time t = t3, the AC voltage V zero-crosses for the first time after the power supply is restored. The alternating voltage V at time t1 is V1, and the alternating voltage V at time t2 is V2.

When a power failure occurs at time t1, the AC voltage V changes from V1 to 0V in an instant. The phase detection means 17 outputs the change amount ΔV of the AC voltage V every predetermined time interval (Δt) to the energization / power failure determination means 18, and the energization / power failure determination means 18 determines that ΔV input from the phase detection means 17 is a predetermined value. As described above, if the changed AC voltage V≈0, it can be determined that a power failure has occurred.
When AC power supply 1 recovers from a power failure at time t2, AC voltage V changes from 0V to V2 in an instant. The energization / power failure determination means 18 can determine that the power has been restored from the power failure if the change amount ΔV input from the phase detection means 17 is equal to or greater than a predetermined value and the AC voltage V = 0 before the change.
Further, the energization / power failure determination means 18 can determine that the AC voltage has zero-crossed if the polarity of the AC voltage V is reversed before and after the predetermined time Δt and the value of ΔV is less than the predetermined value.

  As soon as the control means 19 receives a signal determined by the energization / power failure determination means 18 that the AC power supply 1 has failed based on the detection value of the phase detection means 17, a signal for making the bidirectional switch 10 non-conductive immediately becomes a drive circuit 21. The drive circuit 21 makes the bidirectional switch 10 non-conductive based on the signal. When the bidirectional switch 10 becomes non-conductive, the current flows through the resistor 9 when the AC power source 1 is restored at time t2 and energization is resumed, so that it is possible to prevent an inrush current from flowing through the elements such as the rectifier circuit 3. it can.

  Further, the control means 19 performs control to maintain the non-conductive state without turning on the bidirectional switch 10 until the AC voltage is zero-crossed after the AC power supply 1 is restored, and when the AC voltage is zero-crossed (time t3). To control the bidirectional switch 10 to be conductive. That is, the bidirectional switch 10 is controlled to be off from time t1 to time t3.

  The AC voltage V2 varies depending on the timing at which the AC power supply 1 recovers. For example, it is assumed that the absolute value of the AC voltage V2 becomes the maximum value when the AC power source 1 is restored. In such a case, a large voltage difference occurs between both ends of the resistor 9 immediately after the AC power source 1 is restored at time t2, so when the energization / power failure determination means 18 makes the bidirectional switch 10 conductive at time t2, Inrush current may flow through the bidirectional switch 10 and the rectifier circuit 3. In the first embodiment, the bidirectional switch 10 is non-conductive at the instant of time t2, and AC power is supplied to the rectifier circuit 3 via the resistor 9, and the bidirectional switch 10 is made conductive from time t3. Therefore, it is possible to prevent an inrush current from occurring when the AC power supply 1 is restored.

  In the first embodiment, it has been described that the bidirectional switch 10 is controlled to conduct after the AC voltage has zero-crossed at time t3. However, the timing for making the bidirectional switch 10 conductive is the moment when the zero-crossing is strictly performed. It is not limited to only, and it may be in the vicinity of the zero cross, and includes the moment of zero crossing and the minute time before and after that. That is, it is sufficient that no inrush current flows when the bidirectional switch 10 is turned on for a predetermined time interval including the moment when the zero crossing occurs. Further, the timing at which the bidirectional switch 10 is turned on is not limited to the first zero crossing after the power recovery, and may be the second or subsequent zero crossing.

  Note that information such as setting information set externally and the number of revolutions of the motor 8 is input to the control means 19. The setting information is information such as room temperature and air volume set by the user or the like, for example. The control means 19 calculates the target rotational speed of the motor 8 so as to satisfy the setting information from the input rotational speed of the motor, and the switching element 14 and the inverter 7 so that the motor 8 can achieve the target rotational speed. To control the duty ratio and drive frequency.

Here, a specific structure of the bidirectional switch 10 will be described with reference to FIGS. FIG. 3 shows one form of the bidirectional switch 10, and FIG. 4 shows another form of the bidirectional switch 10.
The bidirectional switch 10 illustrated in FIG. 3 includes a diode bridge 23 and a MOSFET 28. MOSFET is a metal oxide semiconductor field effect transistor and is a kind of switching element. The diode bridge 23 is a diode bridge composed of four diodes 24, a diode 25, a diode 26, and a diode 27.
The point a connected to the power source side contact 11 and the anode of the diode 24 are connected, and the cathode of the diode 24 and the cathode of the diode 25 are connected at the point b. The anode of the diode 24 is connected to the cathode of the diode 27 at a point a. The anode of the diode 25 is connected to the cathode of the diode 26 at a point c, and the point c is connected to the rectifier circuit side contact 12. The anode of the diode 26 and the anode of the diode 27 are connected at a point d.
The point b and the point d are connected via the MOSFET 28. The MOSFET 28 is P type, its drain electrode is connected to the point b, and the source electrode of the MOSFET 28 is connected to the point d. A signal output from the drive circuit 21 is applied to the gate electrode of the MOSFET 28 as a gate voltage.
When a current flows from the power source side contact 11 to the rectifier circuit side contact 12, the current flows in the order of the power source side contact 11, point a, diode 24, point b, MOSFET 28, point d, diode 26 point c, and rectifier circuit side contact 12. . When a current flows from the rectifier circuit side contact 12 to the power source side contact 11, the rectifier circuit side contact 12, point c, diode 25, point b, MOSFET 28, point d, diode 27, point a, and power source side contact 11 are sequentially arranged. Current flows.
The control means 19 can control conduction / non-conduction of the bidirectional switch 10 by turning on / off the MOSFET 28.

The bidirectional switch 10 illustrated in FIG. 4 includes two diodes 29 and 30 and two MOSFETs 31 and 32. MOSFETs 31 and 32 are both P-type. The source electrode of the MOSFET 31 is connected to the power supply side contact 11, and the drain electrode of the MOSFET 31 is connected to the cathode of the diode 29. The anode of the diode 29 is connected to the rectifier circuit side contact 12, and the source electrode of the MOSFET 32 is also connected to the rectifier circuit side contact 12. The drain electrode of the MOSFET 32 is connected to the cathode of the diode 30, and the anode of the diode 30 is connected to the power supply side contact 11.
When a current flows from the power supply side contact 11 to the rectifier circuit side contact 12, the current flows in the order of the power supply side contact 11, the diode 30, the MOSFET 32, and the rectifier circuit side contact 12. When a current flows from the rectifier circuit side contact 12 to the power source side contact 11, the current flows in the order of the rectifier circuit side contact 12, the diode 29, the MOSFET 31, and the power source side contact 11.
A signal output from the drive circuit 21 is applied to the gate electrode of the MOSFET 31 and the gate electrode of the MOSFET 32 as a gate voltage.
The control means 19 turns on / off the MOSFET 32 when a current flows from the power supply side contact 11 to the rectifier circuit side contact 12, and controls the MOSFET 31 when a current flows from the rectifier circuit side contact 12 to the power supply side contact 11. By turning on / off, conduction / non-conduction of the bidirectional switch 10 can be controlled.

  The switching elements included in the bidirectional switch 10 in the first embodiment, that is, the MOSFET 28, the MOSFET 31, and the MOSFET 32 are MOSFET elements using a wide band gap semiconductor, particularly silicon carbide (hereinafter, SiC).

  The wide band gap semiconductor is a general term for semiconductors having a band gap larger than that of silicon (Si), and semiconductors such as SiC, gallium nitride (GaN), and diamond are applicable. In particular, SiC has a band gap of 3.25 eV, which is about three times larger than Si. Switching elements using these wide bandgap semiconductors can be switched at a higher carrier frequency (25 kHz or more) than switching elements using Si, and also have low on-resistance and high heat resistance when energized. SiC has a dielectric breakdown field strength of 3 MV / cm, which is about 10 times larger than Si. Therefore, in the case of a SiC-MOSFET, the SiC epitaxial layer (semiconductor layer) can be made much thinner than Si, and the carrier concentration can be increased, so that high-speed switching with low loss is possible. Become.

FIG. 5 shows the operation of the bidirectional switch 10 when power is restored from a power failure. 5A shows the relationship between the time t and the AC voltage V, as in FIG. 2A. The horizontal axis indicates the time t, and the vertical axis indicates the voltage of the AC voltage that the AC power source 1 applies to the rectifier circuit 3. FIG. V. In FIG. 5, as in FIG. 2, the supply of power from the AC power supply 1 is stopped due to a power failure at time t = t1, the power supply is restored at time t = t2, and the supply of power from the AC power supply 1 is resumed. Shall. At time t = t3, the AC voltage V zero-crosses for the first time after the power supply is restored.
FIGS. 5B and 5C show the relationship between the time t and the on / off state of the bidirectional switch 10. In FIG. 5B and FIG. 5C, the bidirectional switch 10 is turned off at time t1 in the same manner as in FIG. However, from the time t3, unlike the case of FIG. 2B, the bidirectional switch 10 is controlled by PWM (Pulse Width Modulation).
FIG. 5B shows a case where the bidirectional switch 10 is switched at a constant carrier frequency from time t3. In FIG. 5B, the bidirectional switch 10 is switched at an arbitrary frequency of 25 to 60 kHz from time t3 for a predetermined time or until the detection value of the voltage detection means 20 reaches a predetermined value.
FIG. 5C illustrates a case where switching is performed with the carrier frequency decreased from time t3 as time passes. In FIG. 5C, switching of the bidirectional switch 10 is started at an arbitrary frequency between 25 and 60 kHz from the time t3 for a predetermined time or until the detection value of the voltage detection means 20 reaches a predetermined value, and at the end of 25 kHz Switching of the bidirectional switch 10 is terminated at a frequency lower than that.

In this Embodiment 1, since SiC-MOSFET is used for the switching element which bidirectional switch 10 has, a frequency (25 kHz or more) larger than the carrier frequency in which switching element using Si, for example, Si-IGBT is possible. Switching becomes possible. By using the SiC-MOSFET and switching at a high frequency from time t3, the load applied to the smoothing capacitor 16 can be reduced, and the service life of the smoothing capacitor 16 can be extended. Further, switching loss can be reduced by lowering the carrier frequency as time passes from time t3.
5B and 5C show the case where the bidirectional switch 10 is switched at a constant duty ratio, but switching is performed by increasing the duty ratio stepwise or continuously over time. You may let them.

The operation of the bidirectional switch 10 when the AC power source 1 is restored has been described so far, but the operation of the bidirectional switch 10 when the AC power source 1 is interrupted will also be described.
If there is a delay time between the AC power supply 1 power failure and the bidirectional switch 10 becoming non-conductive, the smoothing capacitor 16 is discharged during this time, and the voltage at both ends thereof is lowered. If the AC power supply 1 is restored before the bidirectional switch 10 is turned off, an inrush current may flow through the rectifier circuit 3. In particular, when a mechanical relay is used instead of the bidirectional switch 10, such a problem becomes remarkable because a physical operation is required to disconnect the relay.
Therefore, in the present invention, the bidirectional switch 10 using a switching element is used instead of the mechanical relay. Switching of the bidirectional switch 10 between conduction / non-conduction is performed by turning on / off the switching element, that is, by performing an electrical operation instead of a physical operation, thereby detecting the power failure (time t1). The time until non-conduction can be greatly shortened.
In particular, the first embodiment uses a SiC-MOSFET for the bidirectional switch 10, and its merit is great. Here, the SiC-MOSFET, Si-IGBT, and Si-MOSFET will be compared and described. First, the bidirectional switch 10 is required to satisfy the following three requirements.
(1) There is little energy loss (steady loss) during energization. Since current flows through the bidirectional switch 10 during normal operation, it is naturally desirable that the energy loss be small during energization from the viewpoint of energy saving.
(2) There is little energy loss (switching loss) at the time of switching. In order to reduce the load applied to the smoothing capacitor 16 during power recovery, it is desirable to charge the smoothing capacitor 16 while switching the bidirectional switch 10 during power recovery.
(3) The response speed is fast. Since a rush current may occur if power is restored before the bidirectional switch 10 becomes non-conductive during a power failure, it is desirable that the response speed of the bidirectional switch 10 be fast.

When SiC-MOSFET, Si-IGBT, and Si-MOSFET are applied to the above three requirements, Si-IGBT has a small steady loss, but has a large switching loss and a slow response speed. Si-MOSFET has a small switching loss, but has a large steady loss and a slow response speed. On the other hand, the SiC-MOSFET has a small switching loss and a steady loss, and further has a high response speed.
It should be noted that the response speed here has a correlation with the carrier frequency, and it can be said that the response speed is higher for a switching element capable of increasing the carrier frequency.

  Thus, in this Embodiment 1, since SiC-MOSFET is used for the bidirectional | two-way switch 10, the above three requirements are satisfy | filled and the reliability with respect to energy saving and instantaneous power failure can be improved.

Here, the control method of the power supply apparatus 100 is demonstrated in detail using the flowchart of FIG.
In step 1 (hereinafter, step is abbreviated as S), the user turns on the AC power supply 1 at the start of use. The AC power supply 1 applies an AC voltage to the power supply device 100, and the process proceeds to S2. When the AC power supply 1 is turned on for the first time, the smoothing capacitor 16 is not charged, and if the bidirectional switch 10 is in a conductive state, an inrush current may flow through the elements such as the rectifier circuit 3. Therefore, in S2, the control means 19 outputs a control signal to the drive circuit 21 immediately after the start of energization to control the bidirectional switch 10 to be in a non-conductive state. Thereafter, the process proceeds to S3.
In S3, l11 determines from the output value of the phase detector 17 whether or not the AC voltage has zero-crossed. If it is determined that zero crossing has been performed, the process proceeds to S4. If it is determined that zero crossing has not been performed, S3 is looped.
In S4, the bidirectional switch 10 is turned on from the time when the AC voltage crosses zero, the alternating current is supplied to the bidirectional switch 10 to charge the smoothing capacitor 16, and the driving of the motor 8 is started. Thereafter, the process proceeds to S5.
In S5, the control means 19 determines whether or not to continue the operation of the motor 8. If the operation is not continued, the process proceeds to S6. The case where the operation is not continued means that, for example, when the user inputs a signal for stopping the operation of the apparatus to the control means 19, the control means 19 stops the operation of the motor 8 in S6 based on the input signal. If the operation is continued, the process proceeds to S7 as it is.
In S <b> 7, the energization / power failure determination means 18 determines whether or not a power failure has occurred based on the output value of the phase detection means 17. If it is determined that a power failure has occurred, the process proceeds to S8. If it is determined that a power failure has not occurred, the process returns to S5. Note that the determination as to whether or not a power failure has occurred is made by the method described above.
In S8, the control means 19 outputs a control signal for making the bidirectional switch 10 non-conductive to the drive circuit 21, and makes the bidirectional switch 10 non-conductive. Thereafter, the process proceeds to S9.
In S <b> 9, the energization / power failure determination unit 18 determines whether the AC power source 1 has recovered from the power failure from the output value of the phase detection unit 17. If it is determined that the power has not been recovered from the power failure, S9 is looped, and if it is determined that the power has been recovered from the power failure, the processing returns to S3. It should be noted that the determination as to whether power has been restored from a power failure is made by the method described above.

  As described above, since the bidirectional switch 10 is controlled to be turned off at S2 and S8 at the start of energization and immediately after the power failure recovery, the AC current is a resistance immediately after the AC power source 1 is turned on and immediately after the power recovery. 9, the inrush current does not occur no matter what timing the AC power supply 1 is turned on and restored. Furthermore, since the AC power supply 1 is turned on and restored, the zero cross is detected and control is performed to turn on the bidirectional switch 10 at the moment of zero crossing or before and after that. Generation of current can be prevented.

Embodiment 2. FIG.
In the first embodiment, the power supply device 100 having the configuration in which the bidirectional switch 10 is provided on the line through which the alternating current between the alternating current power supply 1 and the rectifier circuit 3 flows has been described. In the second embodiment, power supply apparatuses 110 and 120 having a configuration in which a switching element is provided on a wiring through which a DC current on the load side from coil 13 flows instead of bidirectional switch 10 will be described. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

FIG. 7 shows a circuit diagram of the power supply device 110 according to the second embodiment. The power supply device 110 includes a P-type P-MOSFET 33 as a switching element on the high-voltage side bus 5 on the load side of the coil 13. The P-MOSFET 33 has a source electrode connected in series with the coil 13, and a drain electrode connected to the smoothing capacitor 16 and the high-voltage side terminal of the inverter 7. The control means 19 outputs a control signal to a drive circuit 34 provided instead of the drive circuit 21. Further, the source potential of the P-MOSFET 33 is input to the drive circuit 34. The gate electrode of the P-MOSFET 33 is connected to the drive circuit 34, and the drive signal output from the drive circuit 34 is applied to the gate electrode of the P-MOSFET 33 as a gate voltage.
The switching element 14 is provided on a wiring connecting the high voltage side bus 5 and the low voltage side bus 6 between the coil 13 and the P-MOSFET 33.

  FIG. 8 shows a circuit diagram of another form of power supply device 120 according to the second embodiment. The power supply device 120 includes an N-type N-MOSFET 35 on the low-voltage bus 6. The N-MOSFET 35 has a source electrode connected to the ground and a drain electrode connected to the smoothing capacitor 16 and the low-voltage side terminal of the inverter 7. The control means 19 outputs a control signal to a drive circuit 36 provided in place of the drive circuit 21. The gate electrode of the P-MOSFET is connected to the drive circuit 36, and the drive signal output from the drive circuit 36 is applied to the gate electrode of the N-MOSFET 35 as a gate voltage. The drive circuit 36 outputs a gate voltage with reference to the ground potential.

The control means 19 controls the P-MOSFET 33 and the N-MOSFET 35 in the same manner as the bidirectional switch 10 of the first embodiment. That is, the control means 19 controls the P-MOSFET 33 and the N-MOSFET 35 based on the determination result of ll2. Referring to the flowchart of FIG. 6 of the first embodiment, when the energization / power failure determination means 18 determines in S7 that a power failure has occurred, the control means 19 performs control to turn off the P-MOSFET 33 and the N-MOSFET 35 in S8. . If the energization / power failure determination means 18 determines that the power supply has been restored in S9, the process returns to S3. If a zero cross of the AC voltage is detected in S3, the control means 19 turns on the P-MOSFET 33 and the N-MOSFET 35 in S4. When the P-MOSFET 33 and the N-MOSFET 35 are turned on in S4, switching may be performed as described above with reference to FIG. Further, when the AC power source 1 is turned on at the start of operation in S1, S3 may be skipped and the process may proceed from S2 to S4.
In the second embodiment, since the P-MOSFET 33 and the N-MOSFET 35 are SiC-MOSFETs, switching can be performed at a carrier frequency of 25 to 60 kHz as already described in the first embodiment, and when the smoothing capacitor 16 is charged. The load applied to the smoothing capacitor 16 can be reduced.

Further, in the power supply device 110, the switching element provided on the high-voltage side bus 5 is the P-type MOSFET 33, so that the drive circuit 34 outputs the gate voltage with reference to the potential from the converter side, that is, the source voltage. Therefore, it is not necessary to provide a separate insulated power supply when generating the gate voltage of the P-MOSFET 33.
Similarly, in the power supply device 120, since the switching element provided on the low voltage side bus 6 is the N-type MOSFET 35, the drive circuit 36 can output the gate voltage with reference to the source voltage which is the ground potential. When creating the gate voltage of the N-MOSFET 35, it is not necessary to provide a separate insulated power supply.

Embodiment 3 FIG.
FIG. 9 is a configuration diagram of the air-conditioning apparatus 200 according to the third embodiment. The air conditioning apparatus 200 includes any one of the power supply apparatuses 100, 110, and 120 described in the first and second embodiments. The third embodiment will be described assuming that the power supply device 100 is provided.

The air conditioner 200 includes an outdoor unit 37 installed outside and an indoor unit 38 installed in an indoor space to be air-conditioned.
The outdoor unit 37 is provided with a compressor 39 that compresses and discharges the refrigerant, and a four-way valve 40 that switches the flow direction of the refrigerant discharged from the compressor 39 according to the heating operation and the cooling operation. The four-way valve 40 has four connecting portions, one connected to the refrigerant discharge pipe of the compressor 39, one connected to the refrigerant suction pipe of the compressor 39, and one provided to the compressor 39. One is connected to a load-side heat exchanger 42 provided in the indoor unit 38. An expansion valve 43 for reducing the pressure of the refrigerant is provided between the heat source side heat exchanger 41 and the load side heat exchanger 42. The outdoor unit 37 is provided with an outdoor blower 44 that blows outdoor air to the heat source side heat exchanger 41. The indoor unit 38 is provided with a load side heat exchanger 42 and an indoor blower 45 that blows indoor air to the load side heat exchanger 42.

The outdoor unit 37 includes a power supply device 100 that converts alternating current supplied from the alternating current power supply 1 into direct current, and a control board 46 that includes an inverter 7 that converts direct current converted by the power supply device 100 into three-phase alternating current. I have. The three-phase alternating current converted by the inverter 7 is supplied from the control board 46 to the motor 8 that drives the drive unit that compresses the refrigerant inside the compressor 39. The motor 8 is provided with means for detecting the rotational speed of the motor 8, and the detected rotational speed is output to the control means 19 of the control board 46.
A remote controller 47 is provided in the room where the indoor unit 38 is installed, and the user can set operation information such as cooling operation, heating operation, and indoor set temperature with the remote controller 47. The information is output to the control means 19.
The control means 19 controls the bidirectional switch 10, the switching element 14, and the inverter 7 based on the input rotation speed of the motor 8, the detection value of the voltage detection means 20, and the operation information set by the remote controller 47.

  As described above, the air-conditioning apparatus 200 according to the third embodiment includes any one of the power supply apparatuses 100, 110, and 120 described in the first and second embodiments. Occurrence of inrush current at the time can be prevented, and the reliability of the apparatus against the inrush current can be improved.

  In the third embodiment, the configuration in which the alternating current converted by the power supply device 100 and the inverter 7 is supplied to the motor 8 of the compressor 39 has been described. However, the motor 8 is not limited to the one used for the compressor 39, and may be a motor used for the outdoor blower 44 or the indoor blower 45.

  The present invention can be used in a power supply device that converts alternating current into direct current.

1 AC power supply, 2 Inrush current prevention circuit, 3 Rectifier circuit, 4 Boost chopper circuit, 5 High voltage side bus, 6 Low voltage side bus, 7 Inverter, 8 Motor, 9 Resistance, 10 Bidirectional switch, 11 Power supply side contact, 12 Rectification Circuit side contact, 13 coil, 14 switching element, 15 diode, 16 smoothing capacitor, 17 phase detection means, 18 energization / power failure determination means, 19 control means, 20 voltage detection means, 21 drive circuit, 22 drive circuit, 23 diode bridge 24, 25, 26, 27 Diode, 28 MOSFET, 29, 30 Diode, 31 MOSFET, 32 MOSFET, 33 P-MOSFET, 34 Drive circuit, 35 N-MOSFET, 36 Drive circuit, 37 Outdoor unit, 38 Indoor , 39 compressor, 40 four-way valve, 41 heat source side heat exchanger, 42 load side heat exchanger, 43 expansion valve, 44 outdoor blower, 45 indoor blower, 46 control board, 47 remote control, 100, 110, 120 power supply, 200 Air conditioner.

Claims (9)

A rectifier circuit for rectifying an alternating current supplied from an alternating current power supply;
Phase detection means for detecting the phase of an AC voltage applied to the rectifier circuit from the AC power supply;
A bidirectional switch provided between the AC power supply and the rectifier circuit, capable of energizing bidirectionally from the AC power supply to the rectifier circuit and from the rectifier circuit to the AC power supply;
A resistor provided in parallel with the bidirectional switch;
A smoothing capacitor that smoothes the current rectified by the rectifier circuit and supplies it to the load side;
Determining means for determining whether or not energization of the alternating current is stopped and whether or not energization of the alternating current is restarted based on the phase detected by the phase detecting means;
The bi-directional switch is controlled to be turned off when the determination unit determines that the energization of the alternating current is stopped, and the phase detection unit detects when the determination unit determines that the energization of the alternating current is resumed. Control means for controlling the bidirectional switch to be turned on near the zero cross of the AC voltage;
Power supply unit with The bidirectional switch has a MOSFET element using a wide band gap semiconductor,
2. The power supply device according to claim 1, wherein the control unit switches between control for turning on and off the bidirectional switch by controlling on and off of the MOSFET element. A rectifier circuit for rectifying an alternating current supplied from an alternating current power supply;
Phase detection means for detecting the phase of an AC voltage flowing from the AC power supply to the rectifier circuit;
A smoothing capacitor that smoothes the current rectified by the rectifier circuit and supplies it to the load side;
A P-type MOSFET element provided on a high-voltage side wiring connecting the rectifier circuit and the load side, a source connected to the rectifier side and a drain connected to the load side;
Determining means for determining whether or not energization of the alternating current is stopped and whether or not energization of the alternating current is restarted based on the phase detected by the phase detecting means;
When the determination means determines that the supply of the alternating current is stopped, the MOSFET element is controlled to be turned off. When the determination means determines that the supply of the alternating current is resumed, the alternating current detected by the phase detection means is detected. Control means for controlling the MOSFET element to be turned on in the vicinity of the zero cross of the voltage;
Power supply unit with A rectifier circuit for rectifying an alternating current supplied from an alternating current power supply;
Phase detection means for detecting the phase of the alternating current flowing from the alternating current power source to the rectifier circuit;
A smoothing capacitor that smoothes the current rectified by the rectifier circuit and supplies it to the load side;
An N-type MOSFET element provided on a low-voltage side wiring connecting the rectifier circuit and the load side, a source connected to the rectifier side and a drain connected to the load side;
Determining means for determining whether or not energization of the alternating current is stopped and whether or not energization of the alternating current is restarted based on the phase detected by the phase detecting means;
When the determination means determines that the supply of the alternating current is stopped, the MOSFET element is controlled to be turned off. When the determination means determines that the supply of the alternating current is resumed, the alternating current detected by the phase detection means is detected. Control means for controlling the MOSFET element to be turned on in the vicinity of the zero cross of the voltage;
Power supply unit with 5. The power supply device according to claim 2, wherein the MOSFET element is a MOSFET element using silicon carbide. 6. The power supply device according to claim 5, wherein the control means starts switching of the MOSFET element by PWM control when the phase detection means detects a zero cross of the alternating current. The power supply apparatus according to claim 6, wherein the control unit lowers a carrier frequency after starting switching of the MOSFET element by PWM control . Voltage detecting means for detecting a voltage across the smoothing capacitor;
The power supply device according to claim 6 or 7, wherein the carrier frequency is lowered when a detection value of the voltage detection means increases. A power supply device according to any one of claims 1 to 8,
An inverter that converts the direct current converted by the power supply device into an alternating current;
A motor driven by the alternating current converted by the inverter;
An air conditioner comprising:

Images