JP5713978B2 - DC power supply device, motor drive device, air conditioner, refrigerator and heat pump water heater - Google Patents

Description

  The present invention relates to a DC power supply device including a plurality of reactors, a motor drive device, an air conditioner, a refrigerator, and a heat pump water heater.

  As a conventional DC power supply device, for example, Patent Document 1 discloses a rectifier circuit that converts an AC voltage of an input power source into a DC voltage and supplies power to a load, a reactor connected to an input side or an output side of the rectifier circuit, A switching means for controlling the accumulation and release of energy to and from the reactor by an on / off operation that is short-circuited through the reactor, a smoothing means for charging by the energy released from the reactor, and an AC voltage for detecting a zero crossing of the power supply AC voltage Zero cross detection means, first control means for performing high frequency switching control of the switching means so that an input current proportional to the power supply AC voltage flows, a preset number of times for each detected zero cross, and a set time, A second control means for controlling the switching means; and a plurality of reactors. The second control is performed in the boost range in which any one of a plurality of reactors can be selected, the switching loss is small, and the second control means having an advantage in circuit efficiency can sufficiently cope with the power factor improvement. The first control is performed by the first control means in a range that cannot be handled. Specifically, one of the first control means and the second control means is selected and switched depending on the magnitude of the load. Further, the switching of the reactor and the switching of the control method may be performed while the reactor is energized. If there is any problem with doing so, the control device temporarily stops energizing the rectifier circuit (the method thereof). However, a power supply device has been proposed that performs switching in a state where no current flows through the reactor.

  In addition, as shown in FIG. 1 of Patent Document 2, the power supply device proposed in Patent Document 2 branches the output of the rectifier circuit into two current paths, and an inductor element L11 is provided in one current path. The inductor element L12 is provided in the other current path. In this power supply device, the current IL11 of L11 is controlled by turning on / off the transistor Q11, and the current IL12 of L12 is controlled by turning on / off the transistor Q12. Further, output currents IL11 and IL12 from L11 and L12 when Q11 and Q12 are off are supplied to the smoothing means via backflow prevention diodes D11 and D12, respectively. Further, the gates of Q11 and Q12 are driven with different phases. As a result, the switching current flowing through each transistor can be reduced, and the ripple component ΔI1 of the current (IL11 + IL12) is further reduced.

JP 2007-135254 A JP 2007-195282 A

  In the power supply device described in Patent Document 1, the first control and the second control are switched to the more efficient one, but when the control is switched while the reactor is energized, the energy stored in the reactor is changed. A high voltage is applied to the reactor switching means, and the reactor switching means is likely to be damaged. On the other hand, if the reactor is switched once stopped, the air conditioner cannot be operated continuously when this power supply device is applied to the air conditioner. The problem which impairs property occurs.

  Moreover, when the power supply device described in Patent Document 1 is applied to an air conditioner, the following problem also occurs. In other words, the power supply device is configured so that the backflow prevention diode always flows regardless of which reactor is switched. However, in the air conditioner, the power supply current is a harmonic current regulation value without operating the switching means. Since there is a case where low load operation is performed as follows, when a full-wave rectification operation is performed without operating the switching means, a reverse current prevention diode is unnecessary, but current flows through the reverse current prevention diode, so the reverse current prevention diode There is a problem that a loss occurs.

  Further, the power supply device described in Patent Document 2 has a problem that a circuit loss at a light load is large because the reactors are connected in parallel. In other words, when the switching means is not operated, the inductance of the rectifier circuit becomes small and harmonic current is likely to be generated. Therefore, even when there is no need to boost the voltage at a low load, the switching means is operated as a countermeasure against harmonic current. There is a problem that the circuit loss at a low load is large. If a plurality of backflow prevention diodes are provided, when a full-wave rectification operation is performed without operating the switching means, a backflow prevention diode is unnecessary, but the current flows through the plurality of backflow prevention diodes. There is a problem that loss occurs.

  In addition, by adopting a wide band gap semiconductor such as SiC as the switching means, it is possible to increase the on / off operating frequency of the switching means and further reduce the inductance of the high frequency reactor of the boosting means. When the reactor is switched from a low-frequency reactor with a large inductance to a high-frequency reactor with a small inductance, the voltage across the smoothing means is higher when the low-frequency reactor is not connected than when the low-frequency reactor is connected. Since it is high, inrush current flows. As the inductance of the high frequency reactor is smaller, inrush current is more likely to flow, leading to failure of the backflow prevention diode, the inductance of the high frequency reactor cannot be reduced, and the performance of a wide band gap semiconductor such as SiC cannot be sufficiently exhibited. Alternatively, even if the inductance of the high-frequency reactor can be reduced, it is necessary to increase the current capacity of the backflow prevention diode, resulting in a high cost.

  Although not described in the power supply device of Patent Document 1, for example, when the AC voltage of the AC power supply is 200V AC or 230V, inrush current until the smoothing means is charged to prevent inrush current when the power is turned on. It is necessary to provide switching means for causing a current to flow through the prevention resistor and for short-circuiting so that no current flows through the inrush current prevention resistor when the smoothing means is charged. For this reason, when the switching means for switching the reactor is provided, a current flows through a total of two switching means, and there is a problem that a loss occurs in the switching means. In particular, if the switching means is a mechanical relay, driving power for the relay is also generated.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a power supply device that does not generate a high voltage exceeding the component breakdown voltage when the reactor is switched in a power supply device using a plurality of reactors.

  It is another object of the present invention to provide a power supply device that does not impair comfort and energy saving even when applied to an air conditioner.

  It is another object of the present invention to provide a power supply device that can eliminate the loss of current flow in the backflow prevention diode and reduce the conversion loss when operating without operating the switching means. It is another object of the present invention to provide a power supply apparatus that can eliminate the loss of current flow in the backflow prevention diode with a single short-circuit means, even if it has a configuration including a plurality of backflow prevention diodes.

  Also, when the inductance of the high frequency reactor is reduced by providing a plurality of boosting means, or by using a wide band gap semiconductor such as SiC as the switching means, the on / off operating frequency of the switching means is increased, and the high frequency reactor It is an object of the present invention to provide a power supply device that can prevent inrush current from flowing when switching between a low-frequency reactor and a high-frequency reactor even when the inductance is further reduced.

  It is another object of the present invention to provide a power supply device that can suppress a loss in a resistor switching means and a reactor switching means for preventing inrush current.

  In order to solve the above-described problems and achieve the object, a DC power supply apparatus according to the present invention includes a rectifying unit that rectifies an AC voltage of an AC power source into a DC voltage, a smoothing unit that smoothes the DC voltage, and the rectifying unit. A low-frequency reactor connected to the input side or output side, a short-circuit means connected in parallel to the low-frequency reactor, a rectifier means and a smoothing means connected between the high-frequency reactor, switching means and backflow prevention One or more boosting means comprising a diode, and a control means for operating the short-circuit means and the switching means are provided.

  According to the present invention, there is an effect that it is possible to realize a DC power supply device in which circuit loss is suppressed.

  Also, when using a low-frequency reactor, the second short-circuiting means is short-circuited so that the high-frequency reactor and the backflow prevention diode are short-circuited. There is an effect that time loss can be reduced.

  Further, even when a plurality of boosting means including a high frequency reactor, a switching means, and a backflow prevention diode are provided, the plurality of high frequency reactors and the backflow prevention diode can be short-circuited by short-circuiting the second short-circuit means. The loss in the backflow prevention diode can be eliminated and the loss at low load can be reduced.

  Further, if the switching means is composed of a wide band gap semiconductor, the switching loss can be reduced and the switching means can be turned on / off, and the switching means can be switched when switching the reactor even if the inductance of the high frequency reactor is further reduced. Since the low-frequency reactor is short-circuited by the short-circuit means after the voltage across the smoothing means exceeds the peak value of the power supply voltage, the low-frequency reactor is short-circuited by the short-circuit means even if the inductance of the high-frequency reactor is small. The inrush current at the moment is small.

  Also, the inrush current at power-on flows through the first reactor and the inrush current prevention resistor, and when the smoothing means is charged, the third short-circuit means is short-circuited, but when the short-circuit means is short-circuited, Since the third short-circuit means is opened, the current only passes through either the short-circuit means or the third short-circuit means, and even if the number of short-circuit means for switching the reactor increases, the loss in the short-circuit means There is an effect that does not increase. Further, when the short-circuit means is a mechanical relay, the effect is great because the relay driving power is not increased.

  Further, since the current flowing through the low frequency reactor is smaller than the maximum current that can be flowed by the DC power supply device, the current capacity of the low frequency reactor can be reduced and the size can be reduced.

FIG. 1 is a diagram illustrating a configuration example of the DC power supply device according to the first embodiment. FIG. 2 is a diagram illustrating a control operation according to the first embodiment. FIG. 3 is a diagram illustrating an example of a power supply current waveform in the low load mode. FIG. 4 is a diagram illustrating an example of a power supply current waveform in the high load mode. FIG. 5 is a diagram illustrating an example of loss-power supply current characteristics in the DC power supply device of the first embodiment. FIG. 6 is a diagram illustrating another configuration example of the DC power supply device according to the first embodiment. FIG. 7 is a diagram illustrating a configuration example of the DC power supply device according to the second embodiment. FIG. 8-1 is a diagram illustrating a control operation according to the second embodiment. FIG. 8-2 is a diagram illustrating a control operation according to the second embodiment. FIG. 9 is a diagram illustrating a configuration example of the DC power supply device according to the third embodiment. FIG. 10A is a diagram illustrating a control operation according to the third embodiment. FIG. 10-2 is a diagram illustrating a control operation according to the third embodiment. FIG. 11 is a diagram illustrating a configuration example of the DC power supply device according to the fourth embodiment. FIG. 12 is a diagram showing an example of a DC power supply device that includes a short-circuit means individually for each backflow prevention diode of each boost means.

  Hereinafter, embodiments of a DC power supply device, a motor drive device, an air conditioner, a refrigerator, and a heat pump water heater according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of a DC power supply device according to the present invention. The DC power supply device according to the present embodiment includes an AC power supply 1, a low frequency reactor 2, a rectifying means 3, a smoothing means 4, high frequency reactors 5a and 5b, switching means 6a and 6b, a backflow prevention diode 7a, 7b, boosting means 8a and 8b, short-circuiting means 10, power supply current detecting means 11, power supply voltage detecting means 12, DC voltage detecting means 13, control means 14, inrush current preventing resistor 16, And a short-circuit means 17. The DC load 9 is a load such as an inverter and operates upon receiving power supply from the DC power supply device. The direct-current power supply device described in the present embodiment and the second and subsequent embodiments can be used as a power supply device for a motor drive device that constitutes an air conditioner, a refrigerator, a heat pump hot water supply device, and the like.

  As shown in FIG. 1, the AC power source 1 is full-wave rectified by the rectifying means 3 via the low frequency reactor 2 and smoothed by the smoothing means 4 via the boosting means 8a and 8b. The boosting means may be a single boosting means 8a, or may be connected in several stages in parallel with the boosting means 8a and the boosting means 8b.

  The low frequency reactor 2 has, for example, an inductance characteristic of 4 mH with respect to a current that is ¼ of an alternating current that can be supplied by the power supply device of the present embodiment. However, the inductance characteristic is not particularly limited, and may be appropriately selected from harmonic current, efficiency, weight, and volume. The short circuit means 10 is connected in parallel to the low frequency reactor 2.

  The boosting means 8a is composed of a high frequency reactor 5a, a switching means 6a and a backflow prevention diode 7a. Similarly, the boosting means 8b is composed of a high frequency reactor 5b, a switching means 6b and a backflow prevention diode 7b.

  The high frequency reactors 5a and 5b have, for example, an inductance characteristic of 200 μH with respect to the maximum AC current that can be flowed by the power supply device of the present embodiment. Moreover, the core with especially small high frequency iron loss is used. However, the inductance characteristic is not particularly limited, and may be appropriately selected from the switching frequency, efficiency, heat, weight, volume, and the like of the switching means 6a and 6b.

  The switching means 6a is composed of an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Are connected to the negative output terminal of the rectifying means 3 and the negative terminal of the smoothing means 4. The switching means 6b has a collector or drain connected between the high frequency reactor 5b and the backflow prevention diode 7b, and an emitter or source connected to the negative output terminal of the rectifying means 3 and the negative terminal of the smoothing means 4.

  The backflow prevention diode 7 a has an anode connected to the high frequency reactor 5 a and the switching means 6 a and a cathode connected to the smoothing means 4. The backflow prevention diode 7 b has an anode connected to the high frequency reactor 5 b and the switching means 6 b and a cathode connected to the smoothing means 4.

  The inrush current preventing resistor 16 is connected between the AC power source 1 and the low frequency reactor 2. The inrush current preventing resistor 16 may be a cement resistor or a PTC (Positive Temperature Coefficient). Further, the short-circuit means 17 is connected in parallel to the inrush current preventing resistor 16.

  A DC load 9 such as an inverter is connected to the smoothing means 4 in parallel. The power supply current detection means 11 is connected between the AC power supply 1 and the rectification means 3, and the power supply voltage detection means 12 is connected to both ends of the AC power supply 1. The DC voltage detection means 13 is connected to both ends of the smoothing means 4.

  The control means 14 is connected to input signal lines from the power supply current detection means 11, the power supply voltage detection means 12 and the DC voltage detection means 13, and to the short circuit means 10, the short circuit means 17, the switching means 6a and the switching means 6b. Output signal lines are connected.

  Next, the operation when the DC power supply device according to the present embodiment is turned on will be described. When the power is turned on in the circuit of FIG. 1, since the smoothing means 4 has no electric charge, a current called a rush current (charging current of the smoothing means 4) flows when the power is turned on, and the rectifying means 3, the backflow prevention diode 7a, The backflow prevention diode 7b may be damaged. Therefore, inrush current is suppressed by using a technique for preventing inrush current. Specifically, the control means 14 opens the short-circuit means 17 and 10 at the initial stage (when the power is turned on) so that a current flows through the inrush current prevention resistor 16 when the power is turned on. As a result, the inrush current is changed from the AC power source 1 → the inrush current preventing resistor 16 → the low frequency reactor 2 → the rectifying means 3 → the high frequency reactors 5a and 5b → the backflow preventing diodes 7a and 7b → the smoothing means 4 → the rectifying means 3 → the AC power source. 1 and the smoothing means 4 is charged. When the charging of the smoothing means 4 is completed, the control means 14 keeps the short-circuit means 17 short-circuited so that no current flows to the inrush current prevention resistor 16 thereafter.

  However, it goes without saying that when the inrush current is small because the voltage of the AC power source 1 is small, the capacity of the smoothing means 4 is small, the impedance of the low frequency reactor 2 is large, or the parts of the path through which the inrush current flows. When the current capacity is large and is not affected by the inrush current, the inrush current preventing resistor 16 and the short-circuit means 17 may not be provided.

  Next, the operation of the DC power supply device will be described with reference to FIG. FIG. 2 is a flowchart showing the operation of the control means 14, and shows the control operation of the short-circuit means 10 and the switching means (switching means 6a, 6b) after completing the above-described power-on operation. As already described, after the power-on operation is completed, the control means 14 keeps the short-circuit means 17 short-circuited so that no current flows through the inrush current preventing resistor 16 (short-circuit means). 17 does not open).

  In the initial state, the control means 14 opens the short-circuit means 10 and the switching means 6a and 6b are stopped. The control means 14 detects the power supply current from the power supply current detection means 11, detects the power supply voltage from the power supply voltage detection means 12, and calculates the power supply power. Further, the voltage across the smoothing means 4 is detected from the DC voltage detection means 13.

  And the control means 14 operates the short circuit means 10 and the switching means 6a and 6b like the flowchart of FIG. In the flowchart, the initial state of each flag and counter is as follows: load state flag = 0 (low load), short-circuit means 10 state flag = 0 (open), switching means state flag = 0 (stopped), short-circuit means 10 operation Time counter = 0 (reset state).

  First, the control means 14 calculates power supply power based on the power supply current detected by the power supply current detection means 11 and the power supply voltage detected by the power supply voltage detection means 12, and compares the power supply power with the threshold value P1 (step S1). .

  When the power source power is less than P1 (step S1: Yes), the control unit 14 determines that the load state is a light load, and sets the load state flag to 0 (low load mode) (step S2). On the other hand, when the power supply power is other than P1 (P1 or more) (step S1: No), the control means 14 compares the power supply power with the threshold value P2 (where P1 <P2) (step S3).

  When the power source power is less than P2 (step S3: Yes), the process proceeds to step S5 without changing the load state flag. When the power source power is P2 or more (step S3: No), the load state flag is set to 1 (high load mode) (step S4).

  In the processes of steps S1 to S4, when each step to be described later is executed to short-circuit or open the short-circuit means 10, when the switching means is operated or stopped, and when the state of the load changes during the state transition process In order to prevent hunting, when the power supply power is P1 or more and less than P2, it has hysteresis to maintain the state of the previous load mode (low load mode if less than P1, high load mode if P2 or more) It is

  When the processes of steps S1 to S4 are completed, the control unit 14 confirms the load state flag (step S5). If the load state flag = 0 (low load mode) (step S5: Yes), the short-circuit unit 10 The status flag is confirmed (step S6).

  When the short-circuit means 10 state flag = 1 (short-circuit) (step S6: Yes), the control means 14 opens the short-circuit means 10 (step S7) and starts counting by the short-circuit means 10 operation time counter (step S8). . Thereafter, it is monitored whether or not the count of the operating time counter of the short-circuit means 10 has reached a predetermined value (here, 100 ms as an example) (step S9). When the count value is less than 100 ms, the monitoring is continued (step S9: No), and when the count value reaches 100 ms (step S9: Yes), the control means 14 clears (resets) the short-circuit means 10 operation time counter. At the same time, the short-circuit means 10 state flag is set to 0 (open) (steps S10 and S11), and the control operation ends. Thereafter, the process proceeds to step S1 to continue the operation.

  In addition, the process of step S8-S10 is a process in case it takes time until the operation | movement is complete | finished after the short circuit means 10 starts operation | movement like a mechanical relay, and when operation time does not take, The processing in steps S8 to S10 may be omitted. Further, the count value (100 ms) is not limited to this, but may be a value that matches the operating time of the short-circuit means 10.

  On the other hand, when the short circuit means 10 state flag = 0 (open) (step S6: No), the control means 14 confirms the switching means state flag (step S12). When the switching means state flag = 1 (in operation) (step S12: Yes), the control means 14 stops the operation (switching) of the switching means 6a and 6b, and sets the switching means state flag to 0 (stopped). Setting is performed (steps S13 and S14), and the control operation ends. If the switching means state flag = 0 (stopped) (step S12: No), the control operation is terminated here. Thereafter, the process proceeds to step S1 to continue the operation.

  As described above, when the control unit 14 determines that the low load mode is set based on the power supply power, the control unit 14 controls the short circuit unit 10 and the switching units 6a and 6b according to steps S6 to S14, and opens the short circuit unit 10 to reduce the low load mode. A current is passed through the frequency reactor 2 and the switching means 6a and 6b are stopped.

  On the other hand, when the load state flag = 1 (high load mode) (step S5: No), the control unit 14 further checks the switching unit state flag (step S15).

  When the switching means state flag = 0 (stopped) (step S15: Yes), the control means 14 starts the operation (switching) of the switching means 6a and 6b and sets the switching means state flag to 1 (in operation). Setting is performed (steps S16 and S17), and the control operation ends. Thereafter, the process proceeds to step S1 to continue the operation.

  On the other hand, when the switching means state flag = 1 (in operation) (step S15: No), the control means 14 checks the short-circuit means 10 state flag (step S18). When the short circuit means 10 state flag = 0 (open) (step S18: Yes), the control means 14 detects the DC voltage detected by the DC voltage detection means 13 (corresponding to the voltage across the smoothing means 4) and the power supply voltage detection means. The peak values of the power supply voltage detected by 12 are compared (step S19). When “DC voltage> power supply voltage peak value” (step S19: Yes), the short-circuit means 10 is short-circuited, and the short-circuit means 10 state flag is set to 1 (short-circuit) (steps S20 and S21). End. Thereafter, the process proceeds to step S1 to continue the operation.

  In step S21, the operation time of the short-circuit means 10 is not taken into consideration, but this is because the influence is small even if the operation time of the short-circuit means 10 is somewhat delayed, and the steps of the short-circuit means 10 are performed as in steps S8 to S10. It is good also as operation which considered operation time.

  When the short circuit means 10 state flag = 1 (short circuit) (step S18: No) and when “DC voltage ≦ power supply voltage peak value” (step S19: No), the control operation ends here. Thereafter, the process proceeds to step S1 to continue the operation.

  As described above, when the control unit 14 determines that the load mode is high based on the power supply power, the control unit 14 controls the short-circuit unit 10 and the switching units 6a and 6b according to steps S15 to S21 to switch the switching units 6a and 6b. At the same time, the short-circuit means 10 is short-circuited based on the DC voltage detected by the DC voltage detection means and the power supply voltage (peak value) detected by the power supply voltage detection means 12. Specifically, switching of the switching means 6a and 6b is started, and the short-circuit means 10 is short-circuited after the DC voltage becomes larger than the peak value of the power supply voltage.

  The explanation of the control operation is as described above. Here, when the load of the DC load 9 is small and the load state flag = 0 (low load), the short-circuit means 10 is open, and the switching means 6a and 6b are stopped. The current flows as follows: AC power supply 1 → low frequency reactor 2 → rectifying means 3 → boosting means 8a / boosting means 8b → smoothing means 4 → rectifying means 3 → AC power supply 1. The power source current is as shown in FIG. The voltage across the smoothing means 4 is a voltage determined by the voltage of the AC power source 1, the inductance of the low frequency reactor 3, the inductances of the reactors 5a and 5b, and the load size of the DC load 9. Since the switching means 6a and 6b are not operated, the voltage cannot be controlled. However, since there is no loss in the switching means 6a and 6b, the conversion loss generated by the conversion of AC voltage → DC voltage is small.

  On the other hand, when the DC load 9 is large and the load state flag = 1 (high load), the short-circuit means 10 is short-circuited, the switching means 6a and 6b are operating, and the control means 14 is connected to both ends of the smoothing means 4. The switching means 6a and 6b are operated so that the voltage is a preset target voltage and the power supply current is a sine wave in phase with the power supply voltage. The operation method of the switching means 6a and 6b is not particularly defined. For example, the method described in “Patent Document 2” may be used. Moreover, it is good also as a structure which added the resistor for electric current detection etc. (not described in FIG. 1) required in order to control switching means 6a and 6b. The power supply current when the short-circuit means 10 is short-circuited and the switching means 6a and 6b are operated has a current waveform as shown in FIG. Since loss occurs in the switching means 6a and 6b, the conversion loss is large when the load of the DC load 9 is small, but no current flows through the low frequency reactor 2 that increases as the load increases. There is no loss, and the conversion loss when the load of the DC load 9 is large is small.

  The order of the operations of the short-circuit means 10 and the switching means 6a and 6b is such that when the DC load 9 becomes large and the short-circuit means 10 is short-circuited to operate the switching means 6a and 6b, the switching means 6a and 6b is operated, the voltage across both ends (DC voltage) of the smoothing means 4 is controlled (boosted) to a target DC voltage equal to or higher than the peak value of the power supply voltage, and then the short-circuit means 10 is short-circuited. When the switching means 6a and 6b are stopped and the short-circuit means 10 is desired to be opened, the switching means 6a and 6b are stopped after the short-circuit means 10 is first opened. This is because, before the switching means 6a and 6b are operated, the voltage across the smoothing means 4 is the voltage of the AC power source 1, the inductance of the low frequency reactor 2, the inductance of the high frequency reactor 5a and the high frequency reactor 5b of the boosting means. The voltage is determined by the magnitude of the load of the DC load 9, and is at least smaller than the peak value of the power supply voltage. Here, the larger the inductance, the lower the voltage across the smoothing means 4, the lower the inductance, the higher the both-end voltage of the smoothing means 4, and the larger the inductance, the higher the power factor (the smaller the inductance). If the short-circuit means 10 is short-circuited from the two points of the power source power factor to prevent the current from flowing through the low-frequency reactor 2, the voltage across the smoothing means 4 must go from a low state to a high state. Without obtaining the short-circuit means, a charging current having a voltage difference tends to flow to the smoothing means 4 (inrush current). Furthermore, since the inductance is small, the inrush current has a large peak current value. Therefore, depending on the inductance values of the low-frequency reactor 2 and the high-frequency reactors 5a and 5b of the boosting means, there is a possibility that the backflow prevention diode having a short-circuit resistance is destroyed. When the switching means 5a and 5b are operated to control the voltage across the smoothing means 4 to be equal to or higher than the peak value of the power supply voltage and then the short-circuit means 10 is short-circuited, no inrush current flows, so that the backflow prevention diode can be protected.

  As described above, the loss of the DC power supply device according to the present embodiment is based on the power supply power (according to the load of the DC load 9) as in the loss-power supply current characteristic example of the present embodiment shown in FIG. Thus, by opening and closing the short-circuit means 10, it is possible to realize a DC power supply device with a small loss over a wide range.

  Moreover, when the low frequency reactor 2 is used, the short-circuit means 10 is opened, and when the low-frequency reactor 2 is not used, the short-circuit means 10 is short-circuited. Reactor switching can be realized without generating Furthermore, since the current flowing through the low frequency reactor 2 may be smaller than the maximum current that can be flowed by the DC power supply device of the present embodiment, the low frequency reactor 2 is made to be lower than the conventional power supply device using the low frequency reactor. Smaller and cheaper.

  Moreover, since the short-circuit means 10 can be opened and closed without stopping the DC power supply device, the air-conditioning apparatus provided with the power supply device of the present embodiment does not impair energy saving and comfort.

  Further, when a wide band gap semiconductor such as SiC is used for the switching means 6a and 6b, the switching loss is reduced. Therefore, the on / off operating frequency of the switching means 6a and 6b is increased, and the high-frequency reactors 5a and 5b Although the inductance can be reduced, on the other hand, if the difference in inductance between the low-frequency reactor 2 and the high-frequency reactors 5a and 5b increases and the short-circuit means 10 is short-circuited so that no current flows through the low-frequency reactor 2, an inrush current Becomes easier to flow. However, in this embodiment, the switching means 6a and 6b are operated so that the voltage across the smoothing means 4 exceeds the peak value of the power supply voltage and then the short-circuit means 10 is short-circuited. Therefore, it is possible to reduce the inductance of the high-frequency reactor and to reduce the capacity of the backflow prevention diode.

  Even if the low-frequency reactor 2 and the short-circuit means 10 are connected between the rectifier means 3 and the booster means as shown in FIG. 6, the same effect is obtained with the same operation as described above. Needless to say. However, in this case, it is necessary to select a low-frequency reactor 2 having a direct current and a short-circuit means 10 having a higher breakdown voltage than the configuration of FIG.

  As described above, the DC power supply device according to the present embodiment includes the low-frequency reactor 2 and the short-circuit means 10 connected in parallel between the AC power supply 1 and the boosting means (boost means 8a and 8b). The low frequency reactor having a large inductance is used by opening the means 10, and the operation of the switching means forming the boosting means is stopped, while the switching means forming the boosting means is operated in a high load state. In addition, the short-circuit means 10 is short-circuited so that no current flows through the low-frequency reactor 2. Thereby, circuit loss can be suppressed low. Further, when short-circuiting means 10 is short-circuited, it is determined that the DC voltage after boosting has become higher than the peak value of the AC voltage output from AC power supply 1, so that the short-circuit means 10 Even if the short-circuit means 10 is short-circuited in a state where current is flowing through the reactor 2, peripheral components such as the short-circuit means 10 can be protected without generating a high voltage in the low-frequency reactor 2. Moreover, since the current flowing through the low frequency reactor 2 is smaller than the maximum current that can be flowed by the DC power supply device, the size can be reduced accordingly.

  Further, when the switching means is composed of a wide band gap semiconductor, the switching loss is small and the on / off operating frequency of the switching means can be increased. Even when the inductances of the high frequency reactors 5a and 5b are further reduced, Since the switching means 6a and 6b are operated so that the voltage across the smoothing means 4 is equal to or higher than the peak value of the power supply voltage, the low-frequency reactor 2 is short-circuited by the short-circuit means 10, so that the inductance of the high-frequency reactors 5a and 5b Even if is small, the inrush current at the moment when the low frequency reactor 2 is short-circuited by the short-circuit means 10 can be reduced.

Embodiment 2. FIG.
In the second embodiment, a DC power supply device capable of further reducing the loss as compared with the first embodiment will be described.

  FIG. 7 is a diagram illustrating a configuration example of the second embodiment of the DC power supply device according to the present invention. In FIG. 7, the same code | symbol is attached | subjected to the same component as the DC power supply device (see FIG. 1) described in the first embodiment. That is, the DC power supply of this embodiment is obtained by adding a short-circuit means 15 to the DC power supply apparatus shown in FIG. 1, and this short-circuit means 15 is connected in parallel to the boosting means 8a and 8b. ing. Specifically, one is connected to the + side output terminal of the rectifier 3 and the other is connected to the cathodes of the backflow prevention diodes 7a and 7b. The short-circuit means 15 may be a mechanism that is turned on when no current is supplied and turned off when current is supplied, such as a B-contact type mechanical relay. In the DC power supply device of the present embodiment, the control means 14 is connected to the output signal line to the short-circuit means 15, and is connected to the short-circuit means 10 and 17 and the switching means 6 a and 6 b that were controlled in the first embodiment. In addition, the short-circuit means 15 is controlled.

  The operation of the DC power supply device of the present embodiment will be described with reference to FIGS. FIGS. 8A and 8B are flowcharts illustrating the operation of the control unit 14 according to the second embodiment. Steps S201 to S209 are added to the flowchart of FIG. 2 used in the description of the first embodiment. It is a thing. In the present embodiment, description of parts common to the first embodiment will be omitted, and only different parts will be described.

  In the initial state, the short circuit means 15 state flag = 1 (short circuit) and the short circuit means 15 operating time counter = 0 (reset state).

  When the switching means state flag = 0 (stopped) in step S12 (step S12: No), the control means 14 checks the short circuit means 15 state flag (step S201). When the short-circuit means 15 state flag = 0 (open) (step S201: Yes), the short-circuit means 15 is short-circuited, and the short-circuit means 15 state flag is set to 1 (short-circuit) (steps S202 and S203), and the control operation ends. It becomes. Thereafter, the process proceeds to step S1 to continue the operation. On the other hand, when the short circuit means 15 state flag = 1 (short circuit) (step S201: No), the control operation ends here. Thereafter, the process proceeds to step S1 to continue the operation.

  Moreover, the control means 14 confirms the short circuit means 15 state flag, when the load state flag = 1 (high load mode) in Step S5 (Step S5: No) (Step S204).

  When the short-circuit means 15 state flag = 1 (short-circuit) (step S204: Yes), the control means 14 opens the short-circuit means 15 (step S205) and starts counting by the short-circuit means 15 operation time counter (step S206). . Thereafter, it is monitored whether or not the count of the short-circuit means 15 operation time counter has reached a predetermined value (here, 100 ms as an example) (step S207). When the count value is less than 100 ms, the monitoring is continued (step S207: No), and when the count value reaches 100 ms (step S207: Yes), the control means 14 clears (resets) the short-circuit means 15 operating time counter. At the same time, the short-circuit means 15 state flag is set to 0 (open) (steps S208 and S209), and the control operation ends. Thereafter, the process proceeds to step S1 to continue the operation. On the other hand, when the short-circuit means 15 state flag = 0 (open) (step S204: No), the process proceeds to step S15.

  In addition, the process of step S206-S208 is a process in preparation for when it takes time until the operation | movement is complete | finished after the short circuit means 15 starts operation | movement like a mechanical relay, and when operation time does not take, The processing in steps S206 to S208 may be omitted. Further, the count value (100 ms) is not limited to this, but may be a value that matches the operating time of the short-circuit means 15. On the other hand, in step S202, the operation time of the short-circuit means 15 is not considered, but this is because the influence is small even if the operation time of the short-circuit means 15 is somewhat delayed. It is good also as operation which considered operation time.

  Here, when the DC load 9 is small and the load state flag = 0 (low load mode), the short-circuit means 10 is open, the short-circuit means 15 is short-circuited, the switching means 6a and 6b are stopped, and the power supply current is The low-frequency reactor 2 → the rectifying means 3 → the short-circuiting means 15 → the smoothing means 4 flows. The waveform of the power supply current is almost the same as that of the first embodiment, but since no current flows through the backflow prevention diodes 7a and 7b, the backflow prevention diodes 7a and 7b are compared with the direct current power supply device of the first embodiment. Loss can be further reduced.

  When the DC load 9 is large and the load state flag = 1 (high load mode), the short-circuit means 10 is short-circuited, the short-circuit means 15 is open, and the switching means 6a and 6b are operating. The same as in the first embodiment.

  As described above, the DC power supply device of the present embodiment further includes the short-circuit means 15 connected in parallel with the boosting means 8a and 8b, and the short-circuit means 15 is short-circuited in a low load state. As a result, when the load is small, no current flows through the backflow prevention diodes 7a and 7b, and no loss occurs in the backflow prevention diodes 7a and 7b. Therefore, the loss can be made smaller than in the first embodiment.

  Even if there is one or a plurality of boosting means, the short-circuit means 15 is connected between the rectifying means and the smoothing means. The loss in the backflow prevention diode can be reduced.

Embodiment 3 FIG.
In the second embodiment, the DC power supply device has been described in which the backflow prevention diode is short-circuited by the short-circuit means 15 to reduce the loss in the low load state. However, in this embodiment, the loss is reduced by the combination with the inrush current prevention circuit. A DC power supply that can be further reduced will be described.

  FIG. 9 is a diagram illustrating a configuration example of the third embodiment of the DC power supply device according to the present invention. In the DC power supply device of this embodiment, the connection destination of one terminal of the short-circuit means 10 provided in the DC power supply device (see FIG. 7) described in Embodiment 2 is not the low frequency reactor 2 but an inrush current. The prevention resistor 16 is changed to one that is not connected to the low frequency reactor 2 (AC power supply 1 side). That is, the short-circuit means 10 of the present embodiment is connected in parallel to the inrush current preventing resistor 16 and the low-frequency reactor 2 that are connected in series, and the DC power supply device short-circuits the short-circuit means 10. In this configuration, no current flows through the inrush current preventing resistor 16 and the low frequency reactor 2.

  In the DC power supply device of the first embodiment or the second embodiment, when the power-on operation is completed, the short-circuit means 17 is maintained in a short-circuited state, and when the DC load 9 is large, the short-circuit means 10 is short-circuited. The current flows through the short-circuit means 17 and the short-circuit means 10. Since the short-circuit means 17 and the short-circuit means 10 also have a slight impedance, a loss occurs in the short-circuit means 17 and the short-circuit means 10 when a large current is passed. Therefore, in the present embodiment, one of the short-circuit means 10 is connected not to the low-frequency reactor 2 but to one of the inrush prevention resistors 16 that is not connected to the low-frequency reactor 2, To avoid the loss.

  The operation of the DC power supply device according to the present embodiment will be described with reference to FIGS. 10-1 and 10-2. FIGS. 10-1 and 10-2 are flowcharts showing the operation of the control unit 14 of the third embodiment, and are compared with the flowcharts of FIGS. 8-1 and 8-2 used in the description of the second embodiment. Steps S301 to S312 are added. In the present embodiment, description of parts common to Embodiments 1 and 2 will be omitted, and only different parts will be described.

  In the initial state, the short-circuit means 17 state flag = 0 (open) and the short-circuit means 17 operating time counter = 0 (reset state).

  When the load state flag = 0 (low load mode) in step S5 (step S5: Yes), the control unit 14 checks the short circuit unit 17 state flag (step S301).

  When the short-circuit means 17 state flag = 0 (open) (step S301: Yes), the control means 14 short-circuits the short-circuit means 17 (step S302) and starts counting by the short-circuit means 17 operation time counter (step S303). . Thereafter, it is monitored whether or not the count of the short-circuit means 17 operating time counter has reached a predetermined value (here, 100 ms is taken as an example) (step S304). If the count value is less than 100 ms, monitoring is continued (step S304: No). If the count value reaches 100 ms (step S304: Yes), the control means 14 clears (resets) the short-circuit means 17 operating time counter. At the same time, the short-circuit means 17 state flag is set to 1 (short-circuit) (steps S305 and S306), and the control operation ends. Thereafter, the process proceeds to step S1 to continue the operation. On the other hand, when the short circuit means 17 state flag = 1 (short circuit) (step S301: No), the process proceeds to step S6.

  In addition, the process of step S303-S305 is a process in preparation for when it takes time until the operation | movement is complete | finished after the short circuit means 17 starts operation | movement like a mechanical relay, and when operation time does not take, The processing in steps S303 to S305 may be omitted. Further, the count value (100 ms) is not limited to this, but may be a value that matches the operating time of the short-circuit means 17.

  Further, the control means 14 determines that “DC voltage> power supply voltage peak value” in step S19 (step S19: Yes), and short-circuits the short-circuit means 10 (step S20). Counting is started (step S307). Thereafter, it is monitored whether or not the count of the operating time counter of the short-circuit means 10 has reached a predetermined value (here, 100 ms as an example) (step S308). If the count value is less than 100 ms, monitoring is continued (step S308: No). If the count value reaches 100 ms (step S308: Yes), the short-circuit means 10 operation time counter is cleared (reset), and further short-circuited. The means 10 state flag is set to 1 (short circuit) (steps S309 and S21).

  In addition, the process of step S307-S309 is a process in preparation for when it takes time until the operation | movement is complete | finished after the short circuit means 10 starts operation | movement like a mechanical relay, and when operation time does not take, The processing of S307 to S309 may be omitted. Further, the count value (100 ms) is not limited to this, but may be a value that matches the operating time of the short-circuit means 10. Further, the short-circuit means 10 operating time counter, the short-circuit means 15 operating time counter, and the short-circuit means 17 operating time counter may be independent, or the same counter may be used.

  Further, when the short-circuit means 10 state flag = 1 (short-circuit) in step S18 (step S18: No), the control means 14 checks the short-circuit means 17 state flag (step S310). When the short circuit means 17 state flag = 1 (short circuit) (step S310: Yes), the short circuit means 17 is opened, and the short circuit means 17 state flag is set to 0 (open) (steps S311 and S312), and the control operation ends. It becomes. Thereafter, the process proceeds to step S1 to continue the operation. On the other hand, when the short-circuit means 17 state flag = 0 (open) (step S310: No), the control operation ends here. Thereafter, the process proceeds to step S1 to continue the operation.

  In step S312, the operation time of the short-circuit means 17 is not taken into account, but this is because the influence is small even if the operation time of the short-circuit means 17 is somewhat delayed, and the steps of the short-circuit means 17 are performed as in steps S303 to S305. It is good also as operation which considered operation time.

  Thus, in the DC power supply device of the present embodiment, the connection destination of one terminal of the short-circuit means 10 is not connected to the low-frequency reactor 2 of the inrush current preventing resistor 16 instead of the low-frequency reactor 2. On the other hand (AC power supply 1 side). Thereby, while the short-circuit means 10 is short-circuited so that current does not flow to the low-frequency reactor 2 at high load, current does not flow to the inrush current prevention resistor 16 even if the short-circuit means 17 is not short-circuited. Therefore, the short-circuit means 17 can be opened, and the loss in the short-circuit means 17 can be eliminated.

Embodiment 4 FIG.
In the first to third embodiments, the DC power supply device that realizes the loss reduction has been described. However, in this embodiment, the short-circuit means 15 connected in parallel to the boosting means is abnormally short-circuited and cannot be opened. The protection operation in the case of failure will be described.

  FIG. 11 is a diagram illustrating a configuration example of the fourth embodiment of the DC power supply device according to the present invention. In FIG. 11, the same code | symbol is attached | subjected to the same component as the DC power supply device (see FIG. 9) described in the third embodiment. That is, the direct current power supply device of the present embodiment is obtained by adding overcurrent protection means 18a and 18b to the direct current power supply device shown in FIG. The overcurrent protection means 18a is connected between the switching means 6a and the -side terminal of the rectifying means 3, and the overcurrent protection means 18b is connected between the switching means 6b and the -side terminal of the rectifying means 3. Input signal lines from the overcurrent protection means 18a and 18b are connected to the control means 14.

  The operation will be described. First, in the state where the control means 14 short-circuits the short-circuit means 10, opens the short-circuit means 15, opens the short-circuit means 17, and operates the switching means 6 a and 6 b, the control means 14 operates abnormally under the influence of noise or the like. The operation in the case where the short circuit time of the switching means 6a has become longer will be described.

  When the short circuit time of the switching means 6a is long, a current flows through the path of the AC power source 1 → the short circuit means 10 → the rectifying means 3 → the high frequency reactor 5a → the switching means 6a → the rectifying means 3 → the AC power source 1. In this case, when the current increases with a slope depending on the power supply impedance and the circuit impedance and reaches a preset protection current value, the overcurrent protection means 18a instructs the switching means 6a output from the control means 14 to operate. Regardless, the operation of the switching means 6a is stopped and information indicating the occurrence of abnormality (referred to as overcurrent abnormality information) is output to the control means 14. When receiving the overcurrent abnormality information from the overcurrent protection unit 18a, the control unit 14 stops the operation of the switching unit 6a.

  Next, an operation in the case where the short-circuit means 15 has some abnormality and cannot be opened in the short-circuit state will be described.

  Since the control means 14 recognizes that the short circuit means 15 has been opened after issuing a command to open the short circuit means 15, the switching means 6 a is operated without detecting any abnormality even if it becomes impossible to open due to some abnormality. I will let you. Then, a current flows through the path of the smoothing means 4 → the short circuit means 15 → the high frequency reactor 5 a → the switching means 6 a → the smoothing means 4. In this case, the increase in current is faster than that in the case where the short-circuit means 15 is normal (open state). However, when the protection current value set in advance is reached, the overcurrent protection means 18a is switched by the control means 14. Regardless of the operation command of the means 6a, the operation of the switching means 6a is stopped and information indicating the occurrence of abnormality (overcurrent abnormality information) is output to the control means 14. When receiving the overcurrent abnormality information from the overcurrent protection unit 18a, the control unit 14 stops the operation of the switching unit 6a. The same applies to the case where the switching means 6b is operated without detecting an abnormality.

  By the way, in the DC power supply devices shown in the second to fourth embodiments, one end of the short-circuiting unit 15 is connected between the rectifying unit 3 and the boosting unit 8a and the boosting unit 8b. However, as shown in FIG. Consider the case where one end of the means 15 is connected to the anode of the backflow prevention diode 7a. As shown in FIG. 12, even if the short-circuit means 15 is connected in parallel to the backflow prevention diode 7a, and the other short-circuit means 15b is connected in parallel to the backflow prevention diode 7b, the switching means 6a and 6b are connected at low load. By short-circuiting the short-circuit means 15 and the short-circuit means 15b when not operating, the same effects as those of each embodiment can be obtained. However, when the switching means 6a is operated in a state where the abnormality of the short-circuit means 15 (a state in which the short-circuit means cannot be opened) occurs, a current flows through the path of the smoothing means 4 → the short-circuit means 15 → the switching means 6a → the smoothing means 4, Since the current does not pass through 5a, the impedance is smaller than that of the DC power supply device of the present embodiment (FIG. 11), the slope of the short-circuit current is increased, the detection of the short-circuit current in the overcurrent protection means 18a is delayed, and the switching means Problems such as the destruction of 6a occur. The same applies when the short-circuit means 15b cannot be opened.

  Thus, even when a short circuit abnormality occurs in the short circuit means 15, since the short circuit current passes through the high frequency reactors 5a and 5b, the overcurrent protection means 18a is interposed between the switching means 6a and 6b and the negative terminal of the rectification means 3. , 18b, the overcurrent can be detected at an early stage, and the overcurrent protection of the switching means 6a, 6b can be realized.

  As described above, the present invention is useful as a DC power supply device that converts a voltage supplied from an AC power supply into a direct current and supplies it to a load.

  DESCRIPTION OF SYMBOLS 1 AC power supply, 2 Low frequency reactor, 3 Rectification means, 4 Smoothing means, 5a, 5b High frequency reactor, 6a, 6b Switching means, 7a, 7b Backflow prevention diode, 8a, 8b Boosting means, 9 DC load, 10, 15, 17, 15b Short-circuit means, 11 Power supply current detection means, 12 Power supply voltage detection means, 13 DC voltage detection means, 14 Control means, 16 Inrush current prevention resistor, 18a, 18b Overcurrent protection means.

Claims (13)

Rectifying means for rectifying the AC voltage of the AC power source into a DC voltage;
Smoothing means for smoothing the DC voltage;
A first reactor connected to the input side or output side of the rectifying means;
Shorting means connected in parallel to the first reactor;
One or more boosting means connected between the rectifying means and the smoothing means, and comprising a second reactor, a switching means and a backflow prevention diode;
Control means for operating the short-circuit means and the switching means;
A power source current detecting means for detecting a current flowing from an AC power source to the rectifying means;
Power supply voltage detection means for detecting the voltage of the AC power supply;
With
The control means includes
Obtain power supply power from the current detected by the power supply current detection means and the voltage detected by the power supply voltage detection means,
When the power supply power is less than a predetermined power value, after the short-circuit means is opened, the operation of the switching means is stopped,
If the source power is less than a predetermined power value, after the DC voltage to operate the switching means is equal to or greater than the peak value of the supply voltage, the DC power supply device according to claim Rukoto to short-circuit the short circuit means.   2. The DC power supply device according to claim 1, wherein the first reactor has a larger inductance value and smaller current capacity than the second reactor, and the second reactor has a small high-frequency iron loss. . The switching means is composed of a wide band gap semiconductor,
The control means is characterized in that the on / off operating frequency of the switching means is made higher and the inductance value of the second reactor is made smaller than that of the switching means made of Si semiconductor. Item 3. The DC power supply device according to Item 1 or 2. DC power supply device according to any one of claims 1 to 3, further comprising a second shorting means connected in parallel with said boosting means. A second short-circuiting means connected in parallel with the series part of the second reactor of the boosting means and the backflow prevention diode;
The control means includes
Obtain power supply power from the current detected by the power supply current detection means and the voltage detected by the power supply voltage detection means,
If the power supply power is less than a predetermined power value, stop the operation of the switching means after opening the short-circuit means, short-circuit the second short-circuit means after stopping the operation of the switching means,
When the power supply power is equal to or higher than a predetermined power value, the switching means is operated after opening the second short-circuit means, and the short-circuit means is short-circuited after the DC voltage becomes equal to or higher than the peak value of the power-supply voltage. The direct-current power supply device according to any one of claims 1 to 4, wherein The first reactor is connected to the input side of the rectifying means;
An inrush current preventing resistor connected between an AC power source and the first reactor or between the first reactor and the input side of the rectifying means;
A third short-circuit means connected in parallel with the inrush current preventing resistor;
With
It said shorting means is a DC power supply device according to any one of claims 1 to 5, characterized in that it is connected in parallel with the series portion between the first reactor and the rush current prevention resistor . In the initial state, the control means is configured such that the short-circuit means and the third short-circuit means are in an open state, and when the smoothing means is charged after being connected to an AC power source, When the load increases and the power supply power increases and the short-circuit means is short-circuited, the third short-circuit means is opened, and when the load is reduced and the power supply power is reduced and the short-circuit means is opened, 7. The DC power supply device according to claim 6 , wherein the short-circuit means is opened after the third short-circuit means is short-circuited. DC power supply device according to claim 6 or 7, characterized in that the current flowing in said switching means further comprises a reaches the predetermined value overcurrent protection means for stopping the operation of said switching means. Rectifying means for rectifying the AC voltage of the AC power source into a DC voltage;
  Smoothing means for smoothing the DC voltage;
  A first reactor connected to the input side of the rectifying means;
  Shorting means connected in parallel to the first reactor;
  One or more boosting means connected between the rectifying means and the smoothing means, and comprising a second reactor, a switching means and a backflow prevention diode;
  Control means for operating the short-circuit means and the switching means;
  An inrush current preventing resistor connected between an AC power source and the first reactor or between the first reactor and the input side of the rectifying means;
  A third short-circuit means connected in parallel with the inrush current preventing resistor;
  With
  The DC power supply device characterized in that the short-circuit means is connected in parallel with a series portion of the inrush current preventing resistor and the first reactor. Motor driving apparatus comprising: a DC power supply device according to any one of claims 1 to 9. An air conditioning apparatus characterized by comprising a motor driving device according to claim 1 0. Refrigerator, characterized in that it comprises a motor driving device according to claim 1 0. The heat pump water heater, characterized in that it comprises a motor driving device according to claim 1 0.

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