WO2023002559A1

WO2023002559A1 - Dc power source device and refrigeration cycle apparatus

Info

Publication number: WO2023002559A1
Application number: PCT/JP2021/027106
Authority: WO
Inventors: 裕一清水; 和徳畠山
Original assignee: 三菱電機株式会社
Priority date: 2021-07-20
Filing date: 2021-07-20
Publication date: 2023-01-26
Also published as: CN117616684A; JPWO2023002559A1

Abstract

A DC power source device (100) comprises: a rectification circuit (2); a reactor (3); a charging unit (4); a charge storage unit (6); and a control unit (10). The charge storage unit (6) has first and second capacitors (6a, 6b) that are connected in series. The charging unit (4) has first and second switching elements (4a, 4b) connected in series and first and second reverse flow prevention elements (5a, 5b), and selectively charges one or both of the first and second capacitors (6a, 6b). The control unit (10) controls, when the rotational speed of a motor provided to a load (8) is equal to or higher than a first speed during control of an operation of the charging unit (4), the first and second switching elements (4a, 4b) so that an electrical capacitance obtained when the charge storage unit (6) is viewed from the charging unit (4) becomes equal to an electrical capacitance of the first or second capacitor (6a, 6b) alone, and individually charges either one of the first and second capacitors (6a, 6b).

Description

DC power supply and refrigeration cycle equipment

The present disclosure relates to a DC power supply that supplies DC power to a load having a motor, and a refrigeration cycle device including the same.

Patent Document 1 below discloses a switching element having first and second switching elements connected in series and first and second capacitors connected in series between output terminals to a load, and output from an AC power supply. A direct current power supply is disclosed that converts an alternating current voltage to a direct current voltage. In this patent document 1, a full-wave rectification mode in which the first and second switching elements are always turned off, and the first and second switching elements are appropriately controlled to be turned on, so that the voltage across the two capacitors is and a boost mode for charging to a voltage equal to or higher than the peak value of the AC voltage.

WO2015/033437

As described above, in the DC power supply device described in Patent Document 1, the two capacitors connected between the output terminals to the load are connected in series. A combined capacitance, which is the capacitance of the two capacitors connected in series, is smaller than the capacitance of the two capacitors alone. For example, if two capacitors have the same capacitance, the combined capacitance of the two capacitors connected in series is half the capacitance of the single capacitor.

If the capacitance of the capacitors is small, the voltage ripple of each capacitor increases when the load of the DC power supply increases, and there is a problem that the deterioration of the life of the capacitors accelerates. In addition, when the capacitance of the capacitor is small, there is a problem that an increase in power source harmonics and deterioration of the power factor are caused, and the efficiency of the DC power supply is deteriorated. Moreover, if a capacitor with a large capacitance is used to solve these problems, another problem arises in that the cost of the device increases.

The present disclosure has been made in view of the above, and aims to obtain a DC power supply device that can contribute to higher efficiency, lower cost, and longer life.

In order to solve the above-described problems and achieve the object, the DC power supply according to the present disclosure is a DC power supply that converts AC power into DC power and supplies DC power to a load having a motor. A DC power supply device includes a rectifier circuit, a reactor, a charge storage section, a charging section, and a control section. The rectifier circuit rectifies an AC voltage, which is the voltage of AC power. A reactor is connected to the input side or the output side of the rectifier circuit. The charge storage section has first and second capacitors connected in series and is connected across the output terminals to the load. The charging unit includes first and second switching elements connected in series, a first backflow prevention element that prevents backflow of charge in the first capacitor, and a second backflow prevention element that prevents backflow of charge in the second capacitor. and two backflow prevention elements to selectively charge one or both of the first and second capacitors. When the control unit controls the operation of the charging unit, if the rotation speed of the motor is equal to or higher than the first speed, the electrostatic capacity when the charge storage unit is viewed from the charging unit is the first or second value. Either one of the first and second capacitors is individually charged by controlling the first and second switching elements so as to have the capacitance of a single capacitor.

The DC power supply device according to the present disclosure has the effect of contributing to higher efficiency, lower cost, and longer life.

1 is a circuit diagram showing a configuration example of a DC power supply device according to Embodiment 1; A diagram showing an example of a switching control state in the DC power supply device according to Embodiment 1. FIG. 2 shows each operation mode in the DC power supply device according to Embodiment 1; FIG. 4 shows a first example of operation waveforms when the DC power supply according to Embodiment 1 operates in operation mode (1); FIG. 4 shows a second example of operation waveforms when the DC power supply according to Embodiment 1 operates in operation mode (1); FIG. 2 is a table summarizing the characteristics of each operation mode in the DC power supply according to Embodiment 1. FIG. Flowchart for explaining the operation of the DC power supply device according to Embodiment 1 FIG. 3 is a block diagram showing a first example of a hardware configuration that implements the functions of the control unit according to Embodiment 1; FIG. 4 is a block diagram showing a second example of a hardware configuration that implements the functions of the control unit according to Embodiment 1; Flowchart for explaining the operation of the DC power supply device according to the second embodiment FIG. 11 shows an example of operation waveforms when the DC power supply according to Embodiment 2 operates in operation mode (2); Flowchart for explaining the operation of the DC power supply device according to the third embodiment A diagram showing a configuration example of a refrigeration cycle device according to Embodiment 6

A DC power supply device and a refrigeration cycle device according to an embodiment of the present disclosure will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are examples, and the scope of the present disclosure is not limited by the following embodiments.

Embodiment 1.
FIG. 1 is a circuit diagram showing a configuration example of a DC power supply device according to Embodiment 1. FIG. A DC power supply device 100 shown in FIG. 1 is configured to convert AC power supplied from an AC power supply 1 into DC power and supply the converted DC power to a load 8 . Although a three-phase power supply is illustrated as the AC power supply 1 in FIG. 1, it is not limited to this example. The AC power supply 1 may be a single-phase power supply. Moreover, the load 8 may be any load as long as it receives supply of DC power and consumes power. In this paper, the load 8 is assumed to be an inverter load that drives a motor of a compressor used in equipment to which a refrigeration cycle is applied. Devices to which the refrigerating cycle is applied include, for example, air conditioners, refrigerators, washer/dryers, refrigerators, dehumidifiers, heat pump water heaters, and showcases. Note that the load 8 is not limited to the load of equipment to which the refrigeration cycle is applied, and may be a vacuum cleaner, a fan motor, a ventilation fan, a hand dryer, an induction heating electromagnetic cooker, or the like.

As shown in FIG. 1, the DC power supply device 100 includes a rectifier circuit 2, a reactor 3, a charging section 4, a charge storage section 6, a first voltage detection section 7a, a second voltage detection section 7b, and a , a third voltage detection unit 7 c and a control unit 10 .

The rectifier circuit 2 is configured as a three-phase full-wave rectifier circuit in which six rectifier diodes are connected in a full bridge. The rectifier circuit 2 rectifies a three-phase AC voltage, which is the voltage of the three-phase AC power supplied from the AC power supply 1 . When the AC power supply 1 is a single-phase power supply, the rectifier circuit 2 is configured as a single-phase full-wave rectifier circuit in which four rectifier diodes are connected in a full bridge.

The charge storage unit 6 has a first capacitor 6a and a second capacitor 6b connected in series. The first capacitor 6a is positioned on the higher potential side, and the second capacitor 6b is positioned on the lower potential side. The first capacitor 6 a and the second capacitor 6 b are charged by the charging section 4 and retain the charges supplied from the charging section 4 .

The charging section 4 has a first switching element 4a and a second switching element 4b connected in series, a first backflow prevention element 5a, and a second backflow prevention element 5b. Charging unit 4 is connected to the output side of rectifier circuit 2 via reactor 3 . A series circuit of the first capacitor 6 a and the second capacitor 6 b is connected between the output terminals to the load 8 between the charging section 4 and the load 8 . Although the reactor 3 is connected to the output side of the rectifier circuit 2 in FIG. 1, the configuration is not limited to this. The reactor 3 may be connected to the input side of the rectifier circuit 2 , that is, between the AC power supply 1 and the rectifier circuit 2 .

An example of the first switching element 4a and the second switching element 4b is the illustrated IGBT (Insulated Gate Bipolar Transistors), but is not limited to this. A MOSFET (Metal Oxide Semiconductor Field Effect Transistor) may be used instead of the IGBT. Semiconductor elements other than IGBTs and MOSFETs may also be used.

Each of the first switching element 4a and the second switching element 4b may have a freewheeling diode connected in anti-parallel for the purpose of suppressing a surge voltage due to switching. When the first switching element 4a and the second switching element 4b are MOSFETs, parasitic diodes formed inside the MOSFETs may be used as free wheel diodes. Materials forming the first switching element 4a and the second switching element 4b include not only silicon (Si) but also silicon carbide (SiC), which is a wide bandgap semiconductor, gallium nitride (GaN), gallium oxide ( Ga ₂ O ₃ ), diamond. By using a semiconductor element made of a wide bandgap semiconductor, low loss and high speed switching can be realized.

The midpoint of the series circuit composed of the first switching element 4a and the second switching element 4b is connected to the midpoint of the series circuit composed of the first capacitor 6a and the second capacitor 6b. The anode of the first backflow prevention element 5a is connected to the collector of the first switching element 4a, and the cathode of the first backflow prevention element 5a is connected to the positive electrode side of the first capacitor 6a. That is, the first backflow prevention element 5a is connected in a direction that prevents the backflow of electric charges in the first capacitor 6a. The cathode of the second backflow prevention element 5b is connected to the emitter of the second switching element 4b, and the anode of the second backflow prevention element 5b is connected to the negative electrode side of the second capacitor 6b. That is, the second backflow prevention element 5b is connected in a direction that prevents the backflow of electric charges in the second capacitor 6b. Moreover, with these configurations, the charging unit 4 selectively charges one or both of the first switching element 4a and the second switching element 4b.

The first voltage detection section 7a detects the capacitor voltage Vpc, which is the voltage of the first capacitor 6a, and the second voltage detection section 7b detects the capacitor voltage Vnc, which is the voltage of the second capacitor 6b. Further, the third voltage detection section 7c detects an output voltage Vdc which is the voltage between the positive electrode of the first capacitor 6a and the negative electrode of the second capacitor 6b. The detected value of the capacitor voltage Vpc detected by the first voltage detector 7a, the detected value of the capacitor voltage Vnc detected by the second voltage detector 7b, and the output voltage detected by the third voltage detector 7c The detected value of Vdc is input to the control unit 10 . The control unit 10 controls the operation of the charging unit 4 based on the detected values of the capacitor voltages Vpc and Vnc and the output voltage Vdc. Specifically, the control unit 10 controls the DC voltage applied to the load 8 by on/off controlling the first switching element 4a and the second switching element 4b. Since there is a relationship of Vdc=Vpc+Vnc between the capacitor voltages Vpc and Vnc and the output voltage Vdc, all of the first voltage detector 7a, the second voltage detector 7b and the third voltage detector 7c need not be provided. Any two of these voltage detection units may be provided, and voltage information acquired from the two voltage detection units may be used to estimate the remaining one voltage.

Next, switching control of the first switching element 4a and the second switching element 4b by the control section 10 will be described with reference to FIGS. 1 to 3. FIG. FIG. 2 is a diagram showing an example of a switching control state in the DC power supply device according to Embodiment 1. FIG. FIG. 3 is a diagram showing each operation mode in the DC power supply device according to Embodiment 1. FIG. In addition, in FIG. 2, the code|symbol of each component is abbreviate|omitted for the simplification of a figure.

State A in FIG. 2 shows a state in which both the first switching element 4a and the second switching element 4b are controlled to be off. In this state, the first capacitor 6a and the second capacitor 6b are charged.

State B in FIG. 2 shows a state in which the first switching element 4a is controlled to be ON and the second switching element 4b is controlled to be OFF. In this state, only the second capacitor 6b is charged.

State C in FIG. 2 shows a state in which the second switching element 4b is controlled to be ON and the first switching element 4a is controlled to be OFF. In this state, only the first capacitor 6a is charged.

State D in FIG. 2 shows a short-circuit state in which both the first switching element 4a and the second switching element 4b are on-controlled. In this state, neither the first capacitor 6a nor the second capacitor 6b are charged.

In the first embodiment, by switching between the states shown in FIG. 2, the DC voltage supplied to the load 8 is controlled while suppressing the rush current in which the current flowing from the AC power supply 1 sharply increases.

FIG. 3 shows each operation mode in the DC power supply device 100 according to the first embodiment. As shown in FIG. 3, the DC power supply device 100 according to Embodiment 1 has nine operation modes (1) to (9). Each operation mode will be described below. Note that A to D in FIG. 3 indicate each state in FIG. Also, the on-duty D1 used in the following description is the ratio of the time during which the first switching element 4a is in the ON state to the total time during which it is in the ON state and the OFF state. Similarly, the on-duty D2 is the ratio of the time during which the second switching element 4b is in the ON state to the total time during which it is in the ON state and the OFF state.

The operation mode (1) is a mode in which the first switching element 4a and the second switching element 4b are always controlled to be off. At this time, the first capacitor 6a and the second capacitor 6b are each charged, and the magnitude of the output voltage Vdc becomes about √2 times the effective value Vac of the AC voltage applied from the AC power supply 1. Also, the first capacitor 6a and the second capacitor 6b are electrically connected in series and charged. Therefore, the electrostatic capacity when the charge accumulating part 6 is viewed from the charging part 4 during charging is the combined electrostatic capacity, which is the total electrostatic capacity of the first capacitor 6a and the second capacitor 6b. The combined capacitance is approximately half the capacitance of the first capacitor 6a or the second capacitor 6b alone.

The operation mode (2) is a mode in which the on-duty D1 of the first switching element 4a is in the range of 0%<D1≦100%, and the second switching element 4b is always in the OFF control state. At this time, the second capacitor 6b is charged, and the magnitude of the output voltage Vdc becomes approximately √2 times the effective value Vac of the AC voltage. In addition, since only the second capacitor 6b is charged, the capacitance of the second capacitor 6b when viewed from the charging unit 4 during charging is the value of the second capacitor 6b alone.

The operation mode (3) is a mode in which the first switching element 4a is always controlled to be off and the on-duty D2 of the second switching element 4b is in the range of 0%<D2≦100%. At this time, the first capacitor 6a is charged, and the magnitude of the output voltage Vdc becomes approximately √2 times the effective value Vac of the AC voltage. In addition, since only the first capacitor 6a is charged, the capacitance of the first capacitor 6a when viewed from the charging unit 4 during charging is the value of the first capacitor 6a alone.

In operation mode (4), the on-duty D1 of the first switching element 4a and the on-duty D2 of the second switching element 4b are in the range of 0%<D1=D2<100%, and the first switching element 4a is driven. In this mode, the phase difference between the signal Gp and the drive signal Gn for the second switching element 4b is 0 degrees. During the period of state D, energy is stored in the reactor 3 by short-circuiting between the positive electrode of the first capacitor 6a and the negative electrode of the second capacitor 6b. During the period of state A, the energy stored in the reactor 3 charges the first capacitor 6a and the second capacitor 6b. Thereby, the magnitude of the output voltage Vdc can be made larger than in the operation modes (1) to (3). Also, the first capacitor 6a and the second capacitor 6b are charged while being electrically connected in series. Therefore, the electrostatic capacitance when the charge accumulating portion 6 is viewed from the charging portion 4 during charging is the combined electrostatic capacitance of the first capacitor 6a and the second capacitor 6b as a whole. 2 is about 1/2 of the capacitance of the single capacitor 6b. Since the phase difference between the drive signal Gp and the drive signal Gn is set to 0 degrees, the magnitude of the capacitor voltage Vpc and the magnitude of the capacitor voltage Vnc are approximately equal. Also, the phase difference does not necessarily have to be 0 degrees, but if there is a phase difference, the capacitor voltage Vpc and the capacitor voltage Vnc become unbalanced.

The operation mode (5) is a mode in which the on-duty D1 of the first switching element is in the range of 0%<D1<100%, and the second switching element 4b is always on. During the period of state D, energy is stored in the reactor 3 by short-circuiting between the positive electrode of the first capacitor 6a and the negative electrode of the second capacitor 6b. During the period of state C, the energy stored in the reactor 3 charges the first capacitor 6a. Thereby, the magnitude of the output voltage Vdc can be made larger than in the operation modes (1) to (3). In addition, since only the first capacitor 6a is charged, the capacitance of the first capacitor 6a when viewed from the charging unit 4 during charging is the value of the first capacitor 6a alone.

The operation mode (6) is a mode in which the first switching element 4a is always on-controlled and the on-duty D2 of the second switching element 4b is in the range of 0%<D2<100%. During the period of state D, energy is stored in the reactor 3 by short-circuiting between the positive electrode of the first capacitor 6a and the negative electrode of the second capacitor 6b. During the period of state B, the energy stored in the reactor 3 charges the second capacitor 6b. Thereby, the magnitude of the output voltage Vdc can be made larger than in the operation modes (1) to (3). In addition, since only the second capacitor 6b is charged, the capacitance when the charge storage unit 6 is viewed from the charging unit 4 during charging is the value of the second capacitor 6b alone.

In operation mode (7), the on-duty D1 of the first switching element 4a and the on-duty D2 of the second switching element 4b are in the range of 0%<D1=D2<50%, and the first switching element 4a is driven. In this mode, the phase difference between the signal Gp and the drive signal Gn for the second switching element 4b is 180 degrees. During state B, the second capacitor 6b is charged, and during state C, the first capacitor 6a is charged. As a result, the magnitude of the output voltage Vdc has a relationship of Vac×√2<Vdc<Vac×2×√2 with respect to the effective value Vac of the AC voltage. Note that the magnitude of the output voltage Vdc is proportional to the on-duties D1 and D2. In addition, since the first capacitor 6a and the second capacitor 6b are charged alternately, the capacitance when the charge storage unit 6 is viewed from the charging unit 4 during charging is the same as that of the first capacitor 6a or the second capacitor 6b. is the value of the capacitor 6b alone.

In operation mode (8), the on-duty D1 of the first switching element 4a and the on-duty D2 of the second switching element 4b are in the range of D1=D2=50%, and the drive signal Gp of the first switching element 4a and In this mode, the phase difference with the drive signal Gn for the second switching element 4b is 180 degrees. During state B, the second capacitor 6b is charged, and during state C, the first capacitor 6a is charged. As a result, the magnitude of the output voltage Vdc is Vdc=Vac×2×√2. In addition, since the first capacitor 6a and the second capacitor 6b are charged alternately, the capacitance when the charge storage unit 6 is viewed from the charging unit 4 during charging is the same as that of the first capacitor 6a or the second capacitor 6b. is the value of the capacitor 6b alone.

In operation mode (9), the on-duty D1 of the first switching element 4a and the on-duty D2 of the second switching element 4b are in the range of 50%<D1=D2<100%, and the first switching element 4a is driven. In this mode, the phase difference between the signal Gp and the drive signal Gn for the second switching element 4b is 180 degrees. During the period of state D, energy is stored in the reactor 3 by short-circuiting the positive electrode of the first capacitor 6a and the negative electrode of the second capacitor 6b. The energy stored in the reactor 3 charges the second capacitor 6b during the state B period, and charges the first capacitor 6a during the state C period. As a result, the magnitude of the output voltage Vdc can have a relationship of Vdc>Vac×2×√2 with respect to the effective value Vac of the AC voltage. In addition, since the first capacitor 6a and the second capacitor 6b are charged alternately, the capacitance when the charge storage unit 6 is viewed from the charging unit 4 during charging is the same as that of the first capacitor 6a or the second capacitor 6b. is the value of the capacitor 6b alone.

As described above, in the DC power supply device 100 according to Embodiment 1, by changing the on-duty D1 of the first switching element 4a and the on-duty D2 of the second switching element 4b, the direct current applied to the load 8 Voltage can be controlled.

Next, the gist of the DC power supply device 100 according to Embodiment 1 will be described with reference to FIGS. 4 to 7. FIG. FIG. 4 is a diagram showing a first example of operation waveforms when the DC power supply according to Embodiment 1 operates in operation mode (1). FIG. 5 is a diagram showing a second example of operation waveforms when the DC power supply according to Embodiment 1 operates in operation mode (1). FIG. 6 is a table summarizing the characteristics of each operation mode in the DC power supply according to the first embodiment. 7 is a flowchart for explaining the operation of the DC power supply device according to Embodiment 1. FIG.

As described above, in operation mode (1), the capacitance of the charge storage unit 6 when viewed from the charging unit 4 is about 1/1 of the capacitance of the first capacitor 6a or the second capacitor 6b alone. 2 is the operation mode. 4 and 5 show operation waveforms when the DC power supply 100 operates in operation mode (1). In each figure, the waveforms of the input current to the rectifier circuit 2, the voltage detected by the third voltage detector 7c, and the voltages detected by the first and

second voltage detectors

7a and 7b are shown in order from the top. ing. Moreover, the horizontal axis of each figure represents time. The difference between the two is that FIG. 4 is an example in which the load power is 15 kW, ie, a light load, whereas FIG. 5 is an example in which the load power is 30 kW, ie, a medium load or heavy load. As shown in FIG. 4, when the load power is relatively small, even in the operation mode (1), the ripple of the output voltage Vdc is kept small. On the other hand, as shown in FIG. 5, when the load power is relatively large, the ripple of the output voltage Vdc becomes large.

In the case of operation mode (1), state A continues as shown in FIGS. Charging is performed in a state of about half the capacitance of the second capacitor 6b alone. Therefore, as shown in FIG. 5, when the load power increases, the ripples of the output voltage Vdc and the output current increase. As a result, as described in the section [Problems to be Solved by the Invention], the life deterioration of the first capacitor 6a or the second capacitor 6b accelerates. Further, if the capacitance of the first capacitor 6a or the second capacitor 6b is small, the efficiency of the DC power supply 100 may be deteriorated due to an increase in power source harmonics and deterioration of the power factor. Moreover, if a capacitor with a large capacitance is used to solve these problems, another problem arises in that the cost of the device increases.

Furthermore, when the load 8 is a compressor used in refrigeration cycle equipment, the drive frequency of the compressor motor is often increased in order to achieve higher refrigeration capacity. In this case, as the induced voltage of the compressor motor increases, it is necessary to apply a higher voltage to the compressor motor. Also, the maximum output voltage of the inverter is determined by the output voltage of the DC power supply 100 . Therefore, in order to apply a higher voltage to load 8, the output voltage of DC power supply 100 must be increased. In view of the above, the DC power supply 100 is required to output a voltage sufficient to drive the load 8, suppress power supply harmonics, and operate with a high power factor.

Based on the above points, each embodiment of this paper uses different operation modes according to the operating conditions of the load. In addition, from the viewpoint of the combined capacitance during charging described above, an operation mode not to be used is determined. Specifically, in each embodiment of this paper, the operation mode (4) is not used. In this paper, operation modes (1) to (3) are referred to as "first operation mode", "second operation mode" and "third operation mode" respectively, and operation modes (5) to ( 9) are sometimes referred to as a "fourth mode of operation", a "fifth mode of operation", a "sixth mode of operation", a "seventh mode of operation" and an "eighth mode of operation", respectively.

Next, the operation of the DC power supply device 100 according to Embodiment 1 will be described. Here, taking the case where the load 8 is a compressor as an example, an embodiment will be described in which operation modes (1) to (3) and operation modes (5) to (9) are selectively used according to the rotation speed of the compressor motor. do.

FIG. 6 shows the magnitude of the output voltage Vdc in operation modes (1) to (9) and the combined capacitance corresponding to each operation mode. , the load torque and the rotation speed are shown.

As described above, the magnitude of the output voltage Vdc is determined by the magnitude of the reactor 3, the on-duty D1 of the first switching element 4a, and the on-duty D2 of the second switching element 4b. Among the operation modes (1) to (9), the operation mode (9) can output the largest output voltage Vdc. When operating mode (9) is used, a voltage lower than the theoretical maximum voltage that can be output may be set as the maximum voltage for practical use in consideration of noise or heat dissipation. In this embodiment, the maximum voltage in actual use is assumed to be Vmax.

First, since the rotational speed of the motor and the induced voltage of the motor are in a proportional relationship, the output voltage Vdc is approximately the same as the induced voltage of the motor. Here, the maximum rotation speed that can be operated at the maximum voltage Vmax in practical use, ie, the upper limit of the rotation speed of the motor, is defined as Nmax. In the operation mode (8), the magnitude of the output voltage Vdc is 2×√2 times the effective value Vac of the AC voltage. Here, the maximum rotation speed that can be operated with this output voltage Vdc=2√2·Vac is assumed to be Nmid. Further, the magnitude of the output voltage Vdc in the operation modes (4) to (7) is in the range of √2·Vac<Vdc<2√2·Vac, and the magnitude of the output voltage Vdc in the operation modes (1) to (3) is The height is Vdc=√2·Vac. Here, the maximum rotational speed that can be operated with this output voltage Vdc=√2·Vac is defined as Nmin. In this paper, the maximum rotation speed Nmin may be called "first speed" and the maximum rotation speed Nmid may be called "second speed".

In this embodiment, the maximum rotation speed for each of these operation modes is used to determine the rotation speed region. Specifically, the rotation speed range of 0 to Nmin is defined as a low speed region, the rotation speed range of Nmin to Nmid is defined as a medium speed region, and the rotation speed range of Nmid to Nmax is defined as a high speed region. In motor control, there are cases where flux-weakening control is used to increase the rotational speed by supplying a current so as to lower the induced voltage of the motor. Therefore, the maximum rotational speeds Nmin, Nmid, and Nmax for each operation mode slightly change depending on the amount of current generated by the flux-weakening control.

In this embodiment, as shown in FIGS. 6 and 7, each operation mode is switched according to the rotational speed range. However, as described above, operation mode (4) is not used. A specific processing flow will be described below with reference to FIG.

First, the control unit 10 determines whether or not the rotational speed is in the low speed range (step S11). If the rotation speed is in the low speed range (step S11, Yes), the control unit 10 selects one of the operation modes (1) to (3) (step S12), and the first operation is performed in the selected operation mode. The switching element 4a and the second switching element 4b are driven (step S13). Henceforth, it returns to step S11 and repeats the processing flow of FIG.

If the rotation speed is not in the low speed range (step S11, No), the control unit 10 determines whether the rotation speed is in the medium speed range (step S14). If the rotation speed is in the middle speed range (step S14, Yes), the control unit 10 selects one of the operation modes (5) to (8) (step S15), and selects the first operation mode in the selected operation mode. The switching element 4a and the second switching element 4b are driven (step S13). Henceforth, it returns to step S11 and repeats the processing flow of FIG.

If the rotation speed is not in the middle speed range (step S14, No), the control unit 10 determines whether the rotation speed is in the high speed range (step S16). It should be noted that although it is highly likely that the rotation speed is in the high-speed region by the determination processing of steps S11 and S14, the possibility that the rotation speed will change after the processing of step S14 is not zero, and the rotation speed is near the boundary of the region. In consideration of the case where the position is located at , the judgment processing of step S16 is provided. If the rotation speed is not in the high speed region (step S16, No), the process returns to step S11 and repeats the processing flow of FIG. On the other hand, if the rotation speed is in the high speed region (step S16, Yes), the control unit 10 selects the operation mode (9) (step S17), and switches the first switching element 4a and the second switching element 4a in the selected operation mode. 2 switching element 4b is driven (step S13). Henceforth, it returns to step S11 and repeats the processing flow of FIG.

With the above processing, an appropriate voltage can be output for the rotation speed of the motor, and the motor can be operated efficiently and stably. When switching the operation mode, the motor rotation speed for determining each speed range is calculated based on the rotation speed command value, the actual rotation speed of the motor obtained from the speed sensor or the position sensor, and the current of the motor. An estimate of the rotational speed obtained can be used.

As described above, the DC power supply device according to the first embodiment selectively selects one or both of the charge storage unit having the first and second capacitors connected in series and the first and second capacitors. and a charging unit for charging the battery. When the rotation speed of the motor is equal to or higher than the first speed, the controller controls the first and second switching elements so that the capacitance when the charge storage unit is viewed from the charging unit becomes a single capacitance. to individually charge either one of the first and second capacitors. When the capacitance of the charge storage unit viewed from the charging unit is the capacitance of the first or second capacitor alone, even when the load power increases, the output voltage and the ripple of the output current are reduced. increase can be suppressed. If the rotation speed of the motor is less than the first speed, the capacitance of the charge storage unit when viewed from the charging unit is 1/2 of the capacitance of the first or second capacitor alone. can also suppress an increase in ripples in the output voltage and output current. If it is possible to suppress the increase in ripples in the output voltage and output current, it is possible to slow down the deterioration of the life of the capacitor, thereby contributing to the extension of the life of the DC power supply.

In addition, when the capacitance of the first and second capacitors is small, there is a problem that an increase in power supply harmonics and deterioration of the power factor are caused, and the efficiency of the DC power supply is deteriorated. Moreover, if a capacitor with a large capacitance is used to solve this problem, another problem arises in that the cost of the device increases. To solve these problems, the control method according to the first embodiment can suppress the increase in the ripples of the output voltage and the output current while suppressing the increase in the capacitance of the first and second capacitors. Therefore, by using the control method according to the first embodiment, it is possible to contribute to the efficiency improvement and cost reduction of the DC power supply.

Next, a hardware configuration for realizing the functions of the control unit in Embodiment 1 will be described with reference to FIGS. 8 and 9. FIG. 8 is a block diagram illustrating a first example of a hardware configuration that implements the functions of the control unit according to Embodiment 1. FIG. 9 is a block diagram illustrating a second example of a hardware configuration that implements the functions of the control unit according to Embodiment 1. FIG.

When realizing part or all of the functions of the control unit 10 in Embodiment 1, as shown in FIG. and an interface 304 for inputting and outputting signals.

The processor 300 may be arithmetic means such as an arithmetic unit, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). The memory 302 includes nonvolatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (registered trademark) (Electrically EPROM), Magnetic discs, flexible discs, optical discs, compact discs, mini discs, and DVDs (Digital Versatile Discs) can be exemplified.

The memory 302 stores a program for executing the functions of the control unit 10 according to the first embodiment. Processor 300 performs the above-described processing by exchanging necessary information via interface 304, executing programs stored in memory 302, and referring to tables stored in memory 302 by processor 300. It can be carried out. Results of operations by processor 300 may be stored in memory 302 .

Also, when implementing part of the functions of the control unit 10 in Embodiment 1, the processing circuit 303 shown in FIG. 9 can also be used. The processing circuit 303 corresponds to a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information to be input to the processing circuit 303 and information to be output from the processing circuit 303 can be obtained via the interface 304 .

Note that part of the processing in the control unit 10 may be performed by the processing circuit 303 and the processing not performed by the processing circuit 303 may be performed by the processor 300 and the memory 302 .

Embodiment 2.
Next, a DC power supply device according to Embodiment 2 will be described. In the second embodiment, an example in which the load 8 is a compressor is taken as an example, and the above-described operation modes are selectively used according to the load torque of the motor of the compressor and the rotational speed of the motor. Note that, in the second embodiment, the operation mode (4) is not used as in the first embodiment. The same applies to other embodiments described below.

The operation mode (1) has the advantage of simple control because the first switching element 4a and the second switching element 4b may be kept in the off state at all times. On the other hand, in the operation mode (1), the capacitance of the charge accumulating portion 6 viewed from the charging portion 4 is approximately half the capacitance of the first capacitor 6a or the second capacitor 6b alone. Therefore, as shown in FIG. 5, when the load power increases, ripples in the output voltage Vdc and the output current increase, leading to an increase in power supply harmonics and a deterioration in the power factor. It should be noted that when operating in operation mode (1), an increase in load power may be considered synonymous with an increase in load torque. Based on the above points, a specific processing flow in the second embodiment will be described with reference to FIG. 10 is a flowchart for explaining the operation of the DC power supply device according to Embodiment 2. FIG.

First, the control unit 10 operates the DC power supply device 100 in operation mode (1) (step S21). Next, the control unit 10 determines whether or not the load torque has increased during operation in operation mode (1) (step S22). If the load torque has not increased (step S22, No), the process returns to step S21 to repeat the process from step S21. On the other hand, if the load torque is increasing (step S22, Yes), it is determined whether or not the rotational speed of the motor has further increased (step S23). If the rotation speed has not increased (step S23, No), the control unit 10 selects either operation mode (2) or operation mode (3), and operates in the selected operation mode (step S24). , the processing flow of FIG. 10 ends. Further, when the rotational speed increases (step S23, Yes), the control unit 10 selects one of the operation modes (5) to (9), operates in the selected operation mode ( Step S25), the processing flow of FIG. 10 is terminated.

It should be noted that the determination process in step S22 may use a method of comparing the load torque increase amount with a threshold value, or a method of comparing the load torque increase ratio with a threshold value. The rotation speed used in the determination process in step S23 may be a rotation speed command value, the actual rotation speed of the motor obtained from a speed sensor or a position sensor, and an estimated rotation speed calculated based on the current of the motor. can be done. Further, when the operation mode (1) is selected during operation in the operation mode selected in step S24 or step S25, the processing flow of FIG. 10 is called again.

According to the process of FIG. 10, when the load torque increases, the operation mode of the DC power supply 100 is changed from the operation mode (1) to the operation mode (2), the operation mode (3), or the operation mode (5). The operation is switched to any one of (9). The operation modes before and after switching are operation modes in which the capacitance when the charge storage unit 6 is viewed from the charging unit 4 is the value of the first capacitor 6a or the second capacitor 6b alone. As a result, even when the load torque increases, it is possible to suppress an increase in ripples in the output voltage and output current. In addition, since the charge storage section 6 can be charged in a state where the electrostatic capacity of the charge storage section 6 when viewed from the charging section 4 is large, power supply harmonics can be suppressed and operation with a high power factor can be performed.

FIG. 11 is a diagram showing an example of operation waveforms when the DC power supply according to Embodiment 2 operates in operation mode (2). The types and display positions of the operating waveforms in FIG. 11 are the same as in FIG. Also, the load power, which is the load condition, is 30 kW, which is the same as in FIG. The on-duty D1 of the first switching element 4a to be turned on is set to "10%". As is clear from the comparison between FIG. 5 and FIG. 11, the ripple of the output voltage Vdc is greatly improved as compared with FIG.

Next, the considerations for implementing the processing flow shown in FIG. 10 will be described. First, operation mode (2) and operation mode (3) are essentially the same in operation, but different in capacitors to be charged. Therefore, by controlling the operation time of the operation mode (2) and the operation time of the operation mode (3) to be approximately the same, the charge/discharge time of each capacitor can be equalized. As a result, the life of the charge accumulating section 6 as a whole can be extended as compared with the case where the charging and discharging times of the capacitors are not equalized. The same relationship applies to operation mode (5) and operation mode (6). Therefore, by controlling the operation time of the operation mode (5) and the operation time of the operation mode (6) to be approximately the same, the charge/discharge time of each capacitor can be equalized.

As described above, according to the DC power supply device according to the second embodiment, the control unit, during the operation in the first operation mode, anticipates an increase in the load torque of the motor and increases the rotation speed of the motor. is expected, control is performed to switch the operation mode to any one of the fourth to eighth operation modes. In addition, even if an increase in the load torque of the motor is expected during operation in the first operation mode, the control unit changes the operation mode to the second operation mode when an increase in the rotation speed of the motor is not expected. or the third operation mode. In these controls, the operation modes before and after switching are operation modes in which the electrostatic capacitance when viewed from the charging unit is the value of the first or second capacitor alone. As a result, even when the load torque increases, it is possible to suppress an increase in ripples in the output voltage and output current. In addition, since the charge storage section can be charged in a state where the electrostatic capacity of the charge storage section when viewed from the charging section is large, it is possible to suppress power supply harmonics and perform operation with a high power factor.

Embodiment 3.
Next, a DC power supply device according to Embodiment 3 will be described. In Embodiment 3, in the DC power supply devices according to

Embodiments

1 and 2, operation mode (1), operation mode (2) or operation mode (3), and operation mode (5) or operation mode A preferred embodiment for transitioning to (6) will now be described. In the following description, as in the second embodiment, the case where the load 8 is a compressor is taken as an example.

FIG. 12 is a flowchart for explaining the operation of the DC power supply device according to Embodiment 3. FIG. Note that the processing flow of FIG. 12 is called each time the compressor is started. In the processing flow of FIG. 12, it is assumed that the number of times the compressor has been started is stored in the memory 302 shown in FIG. 8 or the processing circuit 303 shown in FIG.

During operation in operation mode (1), when a transition to operation mode (2) or operation mode (3) and operation mode (5) or operation mode (6) occurs, the control unit 10 controls the operation of the compressor. The number of activations is confirmed (step S31). If the number of times the compressor has been started is an odd number (step S31, Yes), the control unit 10 operates the DC power supply device 100 in operation mode (2) or operation mode (5) (step S32). If the compressor has been started an even number (step S31, No), the controller 10 causes the DC power supply 100 to operate in operation mode (3) or operation mode (6) (step S33).

According to the processing flow of FIG. 12, it is possible to control the operation time of operation mode (2) and the operation time of operation mode (3) to be approximately the same. Similarly, the operation time of operation mode (5) and the operation time of operation mode (6) can be controlled to be approximately the same. Thereby, the charging and discharging time of each capacitor can be equalized. As a result, the life of the entire charge accumulating section 6 can be extended as compared with the case where the charging and discharging times of the capacitors are not equalized.

Supplementary information about the processing flow in FIG. In step S31 of FIG. 12, "Yes" is determined when the number of times the compressor is started is an odd number, but "No" may be determined. In other words, the operation mode transition conditions may be reversed from those in the example of FIG. Even in this way, the charge/discharge time of each capacitor can be equalized.

In step S31 of FIG. 12, the operation mode transition condition is switched based on the number of times the compressor is started. good. If the charge/discharge time is stored in the memory 302 or the processing circuit 303, the operation mode can be switched so that the charge/discharge time is approximately the same.

As described above, according to the DC power supply device according to Embodiment 3, the control unit performs the second and third operations based on the number of times the load is started or the charging and discharging times of the first and second capacitors. Decide which of the modes of operation to select. This makes it possible to equalize the charging and discharging times of the capacitors, thereby extending the life of the entire charge storage section.

Further, according to the DC power supply device according to the third embodiment, the control unit selects one of the fourth and fifth operation modes based on the number of times the load is started or the charging and discharging times of the first and second capacitors. Decide which operating mode to select. This makes it possible to equalize the charging and discharging times of the capacitors, thereby extending the life of the entire charge storage section.

Embodiment 4.
Next, a DC power supply device according to Embodiment 4 will be described. In the fourth embodiment, an operation mode suitable for starting the DC power supply will be described, taking as an example the case where the load 8 is a compressor.

When the compressor is used in the refrigeration cycle of an air conditioner, for example, the rotation speed command value of the motor of the compressor transitions to the speed increasing side or to the decelerating side depending on the tendency of temperature adjustment of the air conditioner. may be predictable. For example, when the difference between the current temperature and the target temperature is large, a large refrigerating capacity is required, so the motor rotation speed command value is a value in the medium to high speed range. In such a case, starting the motor using operating mode (1) or operating mode (7) would be the preferred embodiment.

Also, as shown in FIG. 6, operation modes (5) to (7) have the same output voltage Vdc range. On the other hand, operation mode (5) and operation mode (6) charge only one of the first capacitor 6a and second capacitor 6b, whereas operation mode (1) and operation mode (7) to (9) are operation modes in which the first capacitor 6a and the second capacitor 6b are alternately charged. In operation mode (5) and operation mode (6), one capacitor is not charged. Therefore, in order to increase the rotation speed of the motor, when transitioning from operation mode (5) or operation mode (6) to operation mode (8) or operation mode (9) capable of outputting a higher voltage, , an inrush current may flow through an uncharged capacitor.

When the inrush current to the charge storage unit 6 is large, the DC power supply device 100 may operate the overcurrent protection function, etc., and stop the device. Moreover, when the overcurrent is large, there is a possibility that the first capacitor 6a and the second capacitor 6b are broken. This kind of rush current can be suppressed by switching the operation mode while gradually changing the on-duty D1 of the first switching element 4a and the on-duty D2 of the second switching element 4b. Therefore, although it is possible to switch the operation mode itself, there is a drawback that the control becomes somewhat complicated. Therefore, it can be said that it is desirable to use operation mode (1) or operation mode (7) under conditions in which the rotation speed of the motor tends to transition to the high speed side.

When the operation mode (1) and the operation mode (7) are used, both the first capacitor 6a and the second capacitor 6b are charged. The inrush current to the charge storage section 6 can be kept small. Thereby, the operation mode can be changed easily and safely. In addition, when the rotation speed of the motor changes to a low speed region or when the load torque increases, the operation mode (1) or operation mode (7) is changed to operation mode (2) or operation mode ( 3) When transitioning to operation mode (5) or operation mode (6), the operating state is such that one of the first capacitor 6a and the second capacitor 6b is discharged. Therefore, by using the operation mode (1) and the operation mode (7), it is possible to avoid the occurrence of a rush current to the charge storage section 6 . That is, by using operation mode (1) and operation mode (7), it is possible to easily and safely transition to operation mode (2), operation mode (3), operation mode (5), or operation mode (6). Transition is possible. Therefore, it can be said that it is desirable to use the operation mode (1) or the operation mode (7) even if the motor rotation speed does not tend to transition to the high speed side. From the above, it is a desirable embodiment to use operation mode (1) or operation mode (7) when starting the motor.

As described above, according to the DC power supply device according to Embodiment 4, the control unit starts up in the first operation mode or the sixth operation mode when starting up the DC power supply device. By doing so, it is possible to easily and safely transition to another operation mode while avoiding the occurrence of rush current to the charge storage section.

Embodiment 5.
Next, a DC power supply device according to Embodiment 5 will be described. In the fifth embodiment, an example in which the load 8 is a compressor is taken as an example, and operation modes (1) to (7) are selectively used according to the amount of circuit loss generated in the DC power supply.

When the current flows through the charging section 4, the number of backflow prevention elements and switching elements present on the current path differs depending on the states A to D, as shown in FIG. Further, the range of Vdc that can be output is the same in each set of operation modes (1) to (3) and operation modes (5) to (7), but as shown in FIG. ~D have different occurrence periods.

Here, for example, in the case of a circuit configuration in which the conduction loss of the first switching element 4a is smaller than the conduction loss of the first backflow prevention element 5a, it is better to operate in operation mode (2) than in operation mode (1). Circuit loss can be reduced. Specifically, in the case of operation mode (1), both the first switching element 4a and the second switching element 4b are always in the OFF control state as shown in FIG. Therefore, in the case of operation mode (1), as shown in FIG. 2, the current always passes through the first backflow prevention element 5a and the second backflow prevention element 5b, and conduction loss occurs in each backflow prevention element. . On the other hand, in the case of operation mode (2), a period of state B occurs as shown in FIG. During state B, the current flows through the first switching element 4a instead of the first backflow prevention element 5a, as shown in FIG. Therefore, in the circuit configuration in which the conduction loss of the first switching element 4a is smaller than the conduction loss of the first backflow prevention element 5a, the conduction loss is smaller in the operation mode (2). 2 and 3, in operation mode (3), current flows through the second switching element 4b instead of the second backflow prevention element 5b, as compared with operation mode (1). Therefore, in the circuit configuration in which the conduction loss of the second switching element 4b is smaller than the conduction loss of the second backflow prevention element 5b, the conduction loss is smaller in the operation mode (3) than in the operation mode (1). .

Also, operation modes (5) and (6) have the same features as operation modes (2) and (3). As described above, the operation mode (4) is not used in each embodiment of this paper, but the features of the operation modes (5) and (6) will be explained in comparison with the operation mode (4).

By comparing operation mode (4) with operation modes (5) and (6), it can be seen that state A is replaced by state B or state C, as shown in FIG. Therefore, as in the operation modes (1) to (3), in the case of a circuit configuration in which the conduction loss of the first switching element 4a is smaller than the conduction loss of the first backflow prevention element 5a, the operation mode ( Conduction loss can be reduced by using operation mode (6) instead of 4). Similarly, in the case of a circuit configuration in which the conduction loss of the second switching element 4b is smaller than the conduction loss of the second backflow prevention element 5b, the operation mode (5) is used instead of the operation mode (4). However, the conduction loss can be reduced.

The conduction losses of the first switching element 4a and the second switching element 4b, and the first backflow prevention element 5a and the second backflow prevention element 5b are known in terms of design. Therefore, by selecting operation modes (1) to (3), (5), and (6) so as to reduce the amount of conduction loss generated, a highly efficient DC power supply 100 can be realized. .

In addition, from the viewpoint of improving the reliability of the DC power supply 100, in the operation modes (1) to (3) or the operation modes (5) to (7) having the same output voltage range, the corresponding The operation mode may be switched as appropriate so that the time integral value of the loss in the set of the switching element and the backflow prevention element becomes approximately the same. As a result, the amount of heat generated by the pairs of corresponding switching elements and backflow prevention elements can be roughly uniformed, the concentration of load on some elements can be avoided, and the life of the device can be extended.

Based on the above viewpoints, the DC power supply according to Embodiment 5 performs the following control. First, when the circuit configuration of the charging unit is such that the conduction loss of the first switching element is smaller than the conduction loss of the first backflow prevention element, the control unit operates in the second operation mode after starting in the first operation mode. Or switch to the fifth operating mode. By controlling in this way, the amount of conduction loss generated can be reduced, so that a highly efficient DC power supply can be realized. Also, after starting in the first operation mode, the operation mode may be switched to the third operation mode or the fourth operation mode. Even with such control, the amount of conduction loss generated can be reduced, and a highly efficient DC power supply can be realized.

Embodiment 6.
In Embodiment 6, refrigeration cycle equipment will be described as an application example of the DC power supply devices according to Embodiments 1 to 5. FIG. FIG. 13 is a diagram illustrating a configuration example of a refrigeration cycle device according to Embodiment 6. FIG.

FIG. 13 shows a configuration example in which an inverter 30 is connected as the load 8 connected to the DC power supply device 100 of FIG. The refrigerating cycle 200 has a compressor 31, a four-way valve 32, an internal heat exchanger 33, an expansion mechanism 34, and a heat exchanger 35, and these parts are sequentially connected via a refrigerant pipe 36, It constitutes a separate type refrigeration cycle device.

A compression mechanism 37 for compressing the refrigerant and a compressor motor 38 for operating the compression mechanism 37 are provided inside the compressor 31 . Compressor motor 38 is driven by inverter 30 .

Next, an example of operation when the refrigeration cycle device shown in FIG. 13 is applied to an air conditioner will be described. When the power consumption of the refrigerating cycle 200 is large, the refrigerating cycle 200 is driven using operation modes (5) to (9) in FIG. Thereby, the output voltage to the refrigerating cycle 200 can be increased. Further, when the power consumption of the refrigerating cycle 200 is small, the refrigerating cycle 200 is driven using operation modes (1) to (3). As a result, the equipment can be operated with a high power factor and high efficiency. Moreover, the methods according to the first to fifth embodiments described above are used for switching between operation modes. Thereby, the effect of each embodiment mentioned above can be received.

It should be noted that the configurations shown in the above embodiments are merely examples, and can be combined with another known technique, or can be combined with other embodiments, or deviate from the gist of the invention. It is also possible to omit or change part of the configuration as long as it is not necessary.

1 AC power supply, 2 rectifier circuit, 3 reactor, 4 charging section, 4a first switching element, 4b second switching element, 5a first backflow prevention element, 5b second backflow prevention element, 6 charge storage section, 6a first capacitor, 6b second capacitor, 7a first voltage detection unit, 7b second voltage detection unit, 7c third voltage detection unit, 8 load, 10 control unit, 30 inverter, 31 compressor, 32 four-way valve, 33 internal heat exchanger, 34 expansion mechanism, 35 heat exchanger, 36 refrigerant pipe, 37 compression mechanism, 38 compressor motor, 100 DC power supply, 200 refrigeration cycle, 300 processor, 302 memory, 303 processing circuit , 304 interfaces.

Claims

A DC power supply that converts AC power into DC power and supplies the DC power to a load having a motor,
a rectifier circuit that rectifies an AC voltage that is the voltage of the AC power;
a reactor connected to the input side or the output side of the rectifier circuit;
a charge storage section having first and second capacitors connected in series and connected between output terminals to the load;
First and second switching elements connected in series, a first backflow prevention element for preventing backflow of charge in the first capacitor, and a second backflow prevention element for preventing backflow of charge in the second capacitor. a charging unit that selectively charges one or both of the first and second capacitors, and has a backflow prevention element;
a control unit that controls the operation of the charging unit;
with
When the rotation speed of the motor is equal to or higher than a first speed, the controller controls the capacitance of the first or second capacitor when viewed from the charging unit. A direct-current power supply that controls the first and second switching elements so as to individually charge one of the first and second capacitors.
When the on-duty of the first switching element is D1 and the on-duty of the second switching element is D2,
a first operation mode in which the first and second switching elements are in a constantly off controlled state;
a second operation mode in which the on-duty D1 of the first switching element is in the range of 0% < D1 ≤ 100% and the second switching element is in a constantly off controlled state; and the first switching element at least one operation mode out of a third operation mode in which the always-off control state is set and the on-duty D2 of the second switching element is in the range of 0%<D2≦100%;
a fourth operation mode in which the on-duty D1 is in the range of 0%<D1<100% and the second switching element is in a constantly ON controlled state; the first switching element is in a constantly ON controlled state; A fifth operation mode in which the on-duty D2 is in the range of 0%<D2<100%, the on-duty D1 is in the range of 0%<D1=D2<50%, and the on-duty D2 is in the range of 0%<D2 <50% range, and a sixth operation mode in which the phase difference between the drive signal for the first switching element and the drive signal for the second switching element is 180 degrees, and the on-duty D1 D1 is in the range of 50%, the on-duty D2 is in the range of D2=50%, and the phase difference between the drive signal for the first switching element and the drive signal for the second switching element is 180 at least one operating mode of a seventh operating mode;
The on-duty D1 is set in the range of 0%<D1<100%, the on-duty D2 is set in the range of 0%<D2<100%, and the drive signal for the first switching element and the second switching element an eighth operation mode in which the phase difference between the drive signal of
The DC power supply device according to claim 1, comprising:
The DC power supply according to claim 2, wherein when starting up the DC power supply, the DC power supply is started in the first operation mode or the sixth operation mode.
operating in any one of the first to third operation modes when the rotational speed of the motor is in a low-speed region below the first speed;
In the middle speed range in which the rotational speed of the motor is equal to or higher than the first speed and lower than the second speed higher than the first speed, one of the fourth to seventh operation modes works with either
The direct-current power supply device according to claim 2, wherein in a high-speed region in which the rotation speed of the motor is equal to or higher than the second speed, the operation mode is the eighth operation mode.
The first speed is a rotational speed that can be operated at √2 times the effective value of the AC voltage,
5. The DC power supply device according to claim 4, wherein the second speed is a rotation speed that can be operated at 2×√2 times the effective value of the AC voltage.
When the load torque of the motor is expected to increase and the rotational speed of the motor is expected to increase during operation in the first operation mode, the control unit changes the operation mode to the fourth operation mode. 6. The direct current power supply according to claim 4 or 5, wherein the operation mode is switched from one of the eighth operating modes.
Even if an increase in the load torque of the motor is expected during operation in the first operation mode, the control unit controls the operation when the rotation speed of the motor is not expected to increase. 6. The direct-current power supply device according to claim 4, wherein the mode is switched to either the second operation mode or the third operation mode.
When the circuit configuration of the charging unit is such that the conduction loss of the first switching element is smaller than the conduction loss of the first backflow prevention element,
The DC power supply device according to any one of claims 4 to 7, wherein the control unit switches to the second operation mode or the fifth operation mode after starting in the first operation mode.
When the circuit configuration of the charging unit is such that the conduction loss of the second switching element is smaller than the conduction loss of the second backflow prevention element,
The DC power supply device according to any one of claims 4 to 7, wherein the control unit switches to the third operation mode or the fourth operation mode after starting in the first operation mode.
The control unit determines which one of the second and third operation modes is to be selected based on the number of times the load is activated or the charging and discharging times of the first and second capacitors. The DC power supply device according to any one of claims 2 to 9.
The control unit determines which one of the fourth and fifth operation modes is to be selected based on the number of times the load is activated or the charging and discharging times of the first and second capacitors. The DC power supply device according to any one of claims 2 to 9.
Refrigeration cycle equipment comprising the DC power supply device according to any one of claims 1 to 11.
The refrigeration cycle equipment according to claim 12, comprising an inverter for driving the motor as the load.