Control devices, power conditioners, heat pump systems and electrical equipment

Abstract

The power pulsation of the DC link section caused by fluctuations in the power consumption of electrical equipment connected to the DC link section is adjusted. [Solution] The control device is a control device that controls one or more converters that transmit first DC power to a DC link unit, where the first DC power includes a first power pulsation that is an AC component, and the DC link unit is configured to be able to transmit second DC power to an electrical device connected to the DC link unit, and the control device has a pulsation acquisition unit that acquires second power pulsation that is an AC component included in the second DC power, and adjusts the first power pulsation according to the second power pulsation acquired by the pulsation acquisition unit.

Description

[Technical Field]

[0001] The present disclosure relates to a control device, a power conditioner, a heat pump system, and an electric device. [Background technology]

[0002] Patent Document 1 discloses a power system including a DC link unit, a grid-connected inverter connected to the DC link unit, one or more DC power sources, a smoothing capacitor, and one or more electrical devices, wherein the electrical devices have a pulsating power adjustment function that adjusts pulsating power components, which are frequency components that are two or more integer multiples of the power supply frequency of the single-phase AC power source, in the DC power consumed by the electrical devices, in accordance with the operation of the grid-connected inverter and the voltage phase of the single-phase AC power source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7514001 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power generation system that reversely flows power generated by solar panels or the like to a grid power supply, a configuration in which electrical equipment such as an air conditioner is connected to a DC link of the power generation system is known. If the fluctuations in power consumption of the electrical equipment connected to the DC link are large, the power fluctuations, i.e., power pulsation, of the DC link will become large, which may result in large distortions in the power that flows back to the grid power supply. The present disclosure aims to adjust power pulsation in a DC link section caused by fluctuations in power consumption of an electrical device connected to the DC link section. [Means for solving the problem]

[0005] A control device according to a first aspect is a control device for controlling one or more converters that transmit first DC power to a DC link unit, the first DC power including a first power pulsation that is an AC component, the DC link unit configured to transmit second DC power to an electric device connected to the DC link unit, the control device including a pulsation acquiring unit that acquires second power pulsation that is an AC component included in the second DC power, and adjusting the first power pulsation in accordance with the second power pulsation acquired by the pulsation acquiring unit. In this case, it is possible to adjust the power pulsation of the DC link unit that is caused by fluctuations in power consumption of the electric device connected to the DC link unit. A control device according to a second aspect is the control device according to the first aspect, wherein the DC link unit is configured to transmit and receive third DC power to and from a capacitor connected to the DC link unit, and the control device adjusts the first power pulsation so as to reduce third power pulsation, which is an AC component included in the third DC power, thereby suppressing a reduction in the life of the capacitor. A control device according to a third aspect is the control device according to the first or second aspect, and adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation, thereby facilitating the adjustment of the power pulsation. A control device according to a fourth aspect is the control device according to any one of the first to third aspects, and adjusts the first power pulsation so that it approaches the second power pulsation, thereby canceling out the power pulsation component. A control device according to a fifth aspect is the control device according to any one of the first to fourth aspects, wherein the DC link unit is connected to the DC link unit and is configured to transmit and receive fourth DC power to and from a grid-connected inverter connected to a single-phase grid power supply, and the control device adjusts a frequency component that is twice the frequency of the grid power supply in the first power pulsation in accordance with fourth power pulsation of the fourth DC power, the frequency component being twice the frequency of the grid power supply. In this case, it is possible to adjust a power pulsation component generated in the grid-connected inverter. A control device according to a sixth aspect is the control device according to any one of the first to fifth aspects, wherein at least one of the converters is connected to a power source and converts power from the power source into the first DC power, thereby making it possible to adjust power pulsation of the DC link unit caused by fluctuations in power consumption of an electrical device connected to the DC link unit. A seventh aspect of the present invention is a control device according to any one of the first to sixth aspects, wherein the pulsation acquisition unit acquires information correlated with the second power pulsation from the electric device, in which case the electric device and the control device can share the arithmetic processing. According to an eighth aspect of the present invention, there is provided a control device according to any one of the first to seventh aspects, wherein the pulsation acquiring unit acquires the second DC power from a DC power measuring unit that measures the second DC power. In this case, even when a plurality of electric devices are provided, the second DC power can be easily acquired. A control device according to a ninth aspect is the control device according to any one of the first to eighth aspects, wherein the electric device includes a rotating electric machine. In this case, it is possible to adjust power pulsation caused by the rotation of the rotating electric machine. A control device according to a tenth aspect is the control device according to the ninth aspect, wherein the second power pulsation pulsates at an integer multiple of the rotation speed of the rotating electric machine. In this case, it is possible to adjust the power pulsation caused by the rotation of the rotating electric machine. A power conditioner according to an eleventh aspect includes the control device according to any one of the first to tenth aspects, one or more converters controlled by the control device, a DC link unit connected to the converter and configured to be connectable to an electric device, and a grid-connected inverter connected to the DC link unit and configured to be connectable to a grid power supply. In this case, it is possible to adjust power pulsation of the DC link unit caused by fluctuations in power consumption of the electric device connected to the DC link unit. A heat pump system according to a twelfth aspect is the power conditioner according to the eleventh aspect, further comprising a refrigeration device as the electric device. In this case, it is possible to adjust power pulsation of the DC link unit caused by fluctuations in power consumption of the electric device connected to the DC link unit. According to a thirteenth aspect, there is provided an electric device connected to a DC link unit, the DC link unit being controlled by a control device and connected to one or more converters that transmit first DC power to the DC link unit, the first DC power including a first power pulsation that is an AC component, the DC link unit being configured to transmit second DC power to the electric device, the control device including a pulsation acquiring unit that acquires second power pulsation that is the AC component included in the second DC power, and configured to adjust the first power pulsation in accordance with the second power pulsation acquired by the pulsation acquiring unit, the electric device including a communication unit that transmits information correlated with the second power pulsation to the pulsation acquiring unit. In this case, it is possible to adjust the power pulsation of the DC link unit that is caused by fluctuations in power consumption of the electric device connected to the DC link unit. In a fourteenth aspect, the electric device according to the thirteenth aspect is a refrigeration device. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a diagram illustrating an example of the configuration of a power system to which a control device according to a first embodiment is applied. [Figure 2] FIG. 2 is a diagram illustrating an example of the hardware configuration of a computer used as a control device. [Figure 3] FIG. 2 is a diagram illustrating an example of a functional configuration of a control device. [Figure 4] FIG. 4 is a diagram illustrating an example of a waveform of power input to an air conditioner. [Figure 5] 1A and 1B are diagrams showing power waveforms in a power system when a control device does not control the power output by a DC / DC converter, where (a) shows an example when the power consumption of an air conditioner is constant, and (b) shows an example when the power consumption of an air conditioner pulsates. [Figure 6] 10A and 10B are diagrams illustrating an example of a power waveform in a power system when a control device controls the power output by a DC / DC converter. [Figure 7] FIG. 10 is a diagram illustrating an example of the configuration of a power system to which a control device according to a second embodiment is applied. [Figure 8]1A and 1B are diagrams showing power waveforms in a power system when a control device does not control the power output by a DC / DC converter, where (a) shows an example when the power consumption of an air conditioner is constant, and (b) shows an example when the power consumption of an air conditioner pulsates. [Figure 9] 10A and 10B are diagrams illustrating an example of a power waveform in a power system when a control device controls the power output by a DC / DC converter. [Figure 10] FIG. 10 is a diagram showing an example of a power waveform in a power system when the power pulsation of power Pload is included in the difference between power Ppv and power Ppcs. [Figure 11] FIG. 1 is a diagram illustrating an example of a power decoupling circuit. [Figure 12] FIG. 10 is a diagram illustrating another example of a power decoupling circuit. [Figure 13] FIG. 1 illustrates an example of a series voltage injector circuit. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. (First embodiment) <Power system configuration> FIG. 1 is a diagram showing an example of the configuration of a power system 1 to which a control device 80 according to the first embodiment is applied. The power system 1 includes a grid-connected inverter 10, a DC link unit 20, a capacitor 30, a solar panel 40, a storage battery 50, an air conditioner 60, a detection circuit 70, and a control device 80. The power system 1 is connected to a three-phase AC power supply 100. The three-phase AC power supply 100 is an example of a grid power supply. In the figure, the grid-connected inverter 10 is referred to as a grid-connected INV. The DC link may also be referred to as a DC link.

[0008] The grid-connected inverter 10 has two input / output units through which power is input and output. One of the input / output units of the grid-connected inverter 10 is configured to be connectable to a three-phase AC power supply 100. The other input / output unit of the grid-connected inverter 10 is connected to a DC link unit 20. A capacitor 30 is connected to the DC link unit 20. A solar panel 40 is connected to the DC link unit 20 via a DC / DC converter 41. A storage battery 50 is connected to the DC link unit 20 via the DC / DC converter 51. An air conditioner 60 is connected to the DC link unit 20. A detection circuit 70 is provided between the DC link unit 20 and the air conditioner 60. An AC current path to which the three-phase AC power supply 100 is connected is referred to as an AC line (referred to as an AC line in FIG. 1 ), and a DC current path to which the DC link unit 20, the solar panel 40, the storage battery 50, and the air conditioner 60 are connected is referred to as a DC line (referred to as a DC line in FIG. 1 ). The grid-connected inverter 10 is provided between an AC line and a DC line.

[0009] The grid-connected inverter 10 is an inverter that can supply power bidirectionally. The grid-connected inverter 10 performs a forward flow operation in which it converts AC power to DC power and supplies power from the three-phase AC power supply 100 side to the DC link unit 20 side. It also performs a reverse flow operation in which it converts DC power to AC power and supplies power from the DC link unit 20 side to the three-phase AC power supply 100 side. The grid-connected inverter 10 interconnects an AC power system and a DC power system. The grid-connected inverter 10 is configured, for example, by a voltage-type two-level inverter using six transistors.

[0010] The DC link unit 20 is a DC current path, one of which is designated as positive (+) and the other as negative (-). The capacitor 30 is connected between the two current paths of the DC link unit 20. The capacitor 30 is, for example, a ceramic capacitor, a film capacitor, an electrolytic capacitor, etc. The DC link unit 20 is configured to be able to transmit and receive power to and from the capacitor 30.

[0011] The solar panel 40 converts light energy into electrical energy through the photoelectric effect. The DC / DC converter 41 is provided between the solar panel 40 and the DC link unit 20, and converts the DC voltage output by the solar panel 40 into a DC voltage for the DC link unit 20 for transmission. The storage battery 50 stores electric energy. The DC / DC converter 51 is provided between the storage battery 50 and the DC link unit 20, and converts the output voltage of the storage battery 50 into a DC voltage of the DC link unit 20 for transmission. Hereinafter, the DC / DC converter 41 and the DC / DC converter 51 may be simply referred to as "DC / DC converters."

[0012] The DC / DC converter may be configured to have a function of performing power conversion in only one direction, converting DC power input from the primary side into predetermined DC power and outputting it to the secondary side. Alternatively, the DC / DC converter may be configured to perform power conversion in both directions, having a function of converting DC power input from the secondary side into predetermined DC power and outputting it to the primary side, in addition to the function of converting DC power input from the primary side into predetermined DC power and outputting it to the secondary side.

[0013] The DC / DC converter circuit configuration can be selected from a step-down circuit, a step-up circuit, or a step-up / step-down circuit depending on the voltage value of the connected power supply or DC line, etc. The converter may also include a power decoupling circuit or a series voltage injector (SVI) that can input substantially constant DC power from the primary side and output highly pulsating DC power from the secondary side. DC / DC converter 41 and DC / DC converter 51 are examples of converters. Note that the converter is not limited to a DC / DC converter, and the converter may be an AC / DC converter that is connected to an AC power source and converts AC voltage into DC voltage.

[0014] The air conditioner 60 is connected to the DC link unit 20 and consumes DC power supplied from the DC link unit 20. The DC link unit 20 is configured to be able to transmit power to the air conditioner 60. The air conditioner 60 has a rotating electric machine, and the rotation speed of the rotating electric machine is controlled by varying it. When the air conditioner 60 is connected to an AC line, an AC / DC converter that converts AC to DC is required. When the air conditioner 60 is connected to the DC link unit 20, an AC / DC converter is not required.

[0015] In electrical equipment that includes a rotating electric machine, the power consumption may include periodic power pulsation due to the rotation of the rotating electric machine. If the power consumption pulsation is large, the power fluctuation, i.e., the power pulsation, of the DC link unit 20 may become large, which may increase the distortion of the power that flows back to the three-phase AC power supply 100. The air conditioner 60 is an example of an electrical device. The electrical device may be a refrigeration device or a ventilation device. The refrigeration device may be, for example, an air conditioner, a water heater, a chiller unit, or a cooling device that cools the air inside a storage unit. The air conditioner may be a dedicated cooling device, a dedicated heating device, or an air conditioner that switches between cooling and heating. The cooling device cools the air inside a refrigerator, a freezer, a showcase, a container, etc.

[0016] The grid-connected inverter 10, the DC link unit 20, the capacitor 30, the control device 80, and the DC / DC converter can be regarded as part of a power conditioner. Furthermore, when a refrigeration unit is connected as an electrical device to the DC link unit 20 in the power conditioner, the power conditioner can be regarded as a heat pump system.

[0017] The air conditioner 60 includes, for example, a single-cylinder positive displacement compressor and a rotating electric machine. The rotating electric machine drives the positive displacement compressor. The output torque of the rotating electric machine is controlled in accordance with the load torque of the positive displacement compressor. The single-cylinder positive displacement compressor has a suction stroke, a compression stroke, and a discharge stroke during one rotation, and the output torque of the rotating electric machine pulsates once per rotation.

[0018] Power pulsation in the power consumed by rotating equipment can be caused by the structure of the rotating electrical machine. For example, due to harmonic components of the magnetic flux density in the air gap between the rotor and stator of a rotating electrical machine, pulsation occurs at a frequency of rotation speed x number of pole pairs x 6. Also, due to differences in magnetic resistance between the slots where the windings are wound and the iron core, pulsation occurs at a frequency of rotation speed x (least common multiple of the number of slots and the number of poles).

[0019] Power pulsation in power consumption by rotating equipment can be caused by a power converter that drives the rotating electrical machine. For example, when vibration suppression control is performed to control the output torque of the rotating electrical machine in accordance with the periodically pulsating load torque, the power pulsation occurs at the fundamental frequency of the load torque. The power consumption of the air conditioner 60 pulsates at an integral multiple of the rotation speed of the rotating electrical machine.

[0020] The detection circuit 70 measures the power consumption of the air conditioner 60 and transmits information related to the measured power to the control device 80. The detection circuit 70 may measure the input power to the air conditioner 60, or may be configured to measure the DC current supplied from the DC link unit 20. The detection circuit 70 measures the current using, for example, a current sensor, and amplifies the signal to measure the power consumption of the air conditioner 60. The detection circuit 70 transmits information related to the measured power to the control device 80. The detection circuit 70 is an example of a DC power measurement unit.

[0021] The control device 80 controls the DC / DC converter that transmits power to the DC link unit 20. The DC / DC converter 41 and the DC / DC converter 51 may be controlled by one control device 80, or a configuration may be such that a control device 80 is provided for each DC / DC converter. The control device 80 may also be configured as an independent device, or may be incorporated into any of the DC / DC converter, the grid-connected inverter 10, or the air conditioner 60.

[0022] The control device 80 acquires power pulsation (second power pulsation), which is an AC component included in the power input from the DC link unit 20 to the air conditioner 60. The control device 80 adjusts the power pulsation (first power pulsation) to be superimposed on the DC power output by the DC / DC converter according to the acquired second power pulsation. The control device 80 adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation, for example, by adding, to the DC power output by the DC / DC converter, an AC component whose amplitude information and phase information match those of the second power pulsation. The functional configuration of the control device 80 will be described in detail later.

[0023] The name of the power and the direction in which the power is supplied to each device are defined in Figure 1. In Figure 1, the direction in which the power is supplied is indicated by an arrow. The power when the grid-connected inverter 10 performs reverse power flow operation is denoted as power Ppcs. The direction in which the power Ppcs is supplied from the DC link unit 20 side to the three-phase AC power supply 100 side is defined as positive (+). The power Ppcs is an example of fourth DC power.

[0024] The power supplied to the capacitor 30 is denoted as power PC. The direction in which the power PC is supplied from the DC link unit 20 to the capacitor 30 is positive (+). The power PC is an example of a third DC power. The power transmitted by the DC / DC converter 41 is denoted as power Ppv. The direction in which the power Ppv is supplied from the solar panel 40 to the DC link unit 20 is positive (+). The power Ppv is an example of a first DC power.

[0025] The power transmitted by the DC / DC converter 51 is referred to as power Pbattery. The direction in which the power Pbattery is supplied from the storage battery 50 to the DC link unit 20 is positive (+). If the power Pbattery is positive (+), the storage battery 50 is discharging, and if it is negative (-), the storage battery 50 is charging. The power Pbattery is an example of a first DC power. The power consumed by the air conditioner 60 is represented as power Pload. The direction in which the power Pload is supplied from the DC link unit 20 to the air conditioner 60 is positive (+). The power Pload is an example of second DC power.

[0026] 2 is a diagram showing an example of the hardware configuration of a computer 800 used as the control device 80. The computer 800 includes a CPU (Central Processing Unit) 801, a RAM (Random Access Memory) 802, and a ROM (Read Only Memory) 803. The RAM 802 is a volatile memory used as a work area when the CPU 801 executes a program. The ROM 803 is a non-volatile memory that stores the program executed by the CPU 801 and other data. The CPU 801 uses the RAM 802 as a work area and executes a program read from the ROM 803. The computer 800 also includes an IF (interface) 804 for communication.

[0027] <Controller functional configuration> FIG. 3 is a diagram illustrating an example of the functional configuration of the control device 80. As shown in FIG. The control device 80 includes a pulsation information acquisition unit 81, a pulsation identification unit 82, an output determination unit 83, and a signal transmission unit 84 as functions executed by a CPU 801, which is a processor.

[0028] The pulsation information acquisition unit 81 acquires information on the second power pulsation, which is an AC component included in the power Pload (hereinafter referred to as "power pulsation information") The pulsation information acquisition unit 81 acquires the power pulsation information from the detection circuit 70, for example. The power pulsation information is, for example, the power Pload measured by the detection circuit 70 .

[0029] The pulsation information acquisition unit 81 may also acquire power pulsation information from the air conditioner 60. In this case, the air conditioner 60 includes a communication unit that transmits the power pulsation information to the control device 80. The function of the communication unit is executed by a hardware configuration similar to that of the computer 800 shown in FIG. The power pulsation information is information relating to the operating state of the air conditioner 60, such as the rotation angle of the rotating electrical machine of the air conditioner 60 or the amplitude of the power pulsation, or information for identifying the second power pulsation, such as a value correlated thereto. Alternatively, the communication unit of the air conditioner 60 may be configured to transmit the second power pulsation estimated from the operating state of the air conditioner 60 or identified by frequency analysis in the air conditioner 60. In this case, the control device 80 does not need to include the pulsation identification unit 82, thereby reducing the processing load on the control device 80.

[0030] The pulsation information acquisition unit 81 may also be configured to acquire power pulsation information from both the detection circuit 70 and the air conditioner 60. The pulsation information acquisition unit 81 acquires the measured power Pload from the detection circuit 70. The pulsation information acquisition unit 81 also acquires information relating to the operating state of the air conditioner 60 from the air conditioner 60.

[0031] The pulsation identifying unit 82 identifies the second power pulsation based on the power pulsation information acquired by the pulsation information acquiring unit 81. For example, when the pulsation information acquisition unit 81 acquires the power Pload measured by the detection circuit 70, the pulsation identification unit 82 performs frequency analysis on the power Pload to identify the second power pulsation. The frequency analysis is, for example, a short-time Fourier transform using a window function. In the short-time Fourier transform, power consumption over a predetermined period of time is extracted and subjected to a Fourier transform. The predetermined period of time may be, for example, an integer multiple of the period of the three-phase AC power supply 100, which is the system power supply.

[0032] When the pulsation information acquisition unit 81 acquires power pulsation information from both the detection circuit 70 and the air conditioner 60, the pulsation identification unit 82 performs frequency analysis on the power Pload based on information about the operating state of the air conditioner 60 to identify the second power pulsation. The pulsation identification unit 82 performs a short-time Fourier transform using, for example, a window function based on the information about the operating state of the air conditioner 60. In this case, for example, a window function that extracts power consumption over a period corresponding to the rotation speed of the rotating electric machine is used. Alternatively, for example, a window function that extracts power consumption over an integer multiple of the reciprocal of the rotation speed corresponding to one cycle of time is used. The pulsation information acquiring unit 81 and the pulsation identifying unit 82 are an example of a pulsation acquiring unit.

[0033] The output determining unit 83 determines the first power pulsation to be superimposed on the DC power output by the DC / DC converter based on the second power pulsation. The output determination unit 83 determines the first power pulsation so as to reduce the third power pulsation, which is, for example, an AC component included in the power PC supplied to the capacitor 30. The third power pulsation pulsates at the same frequency as the second power pulsation. This reduces the power pulsation absorbed by the capacitor 30, thereby suppressing voltage fluctuations on the DC line. Furthermore, it is no longer necessary for the capacitor 30 to absorb the power pulsation of the power consumed by the air conditioner 60, which reduces heat generation in the capacitor 30 due to the power pulsation and suppresses a reduction in the lifespan of the capacitor 30.

[0034] The output determining unit 83 may determine the first power pulsation so as to approximate the second power pulsation, for example. Alternatively, the output determining unit 83 may determine the first power pulsation in accordance with the power pulsation (fourth power pulsation) of the fourth DC power (Ppcs), which has a frequency component twice the frequency of the three-phase AC power supply 100, which is the system power supply. In this case, the control device 80 adjusts the frequency component twice the frequency of the three-phase AC power supply 100 in the first power pulsation. The signal transmitting unit 84 outputs to the DC / DC converter a control signal on which the determined first power pulsation is superimposed and output.

[0035] <Example> 4 is a diagram showing an example of the waveform of the power input to the air conditioner 60. The vertical axis represents power (W) and the horizontal axis represents time (sec). The air conditioner 60 is equipped with a rotating electric machine, and the power consumption of the air conditioner 60 pulsates due to the rotating electric machine. The power Pload input to the air conditioner 60 is expressed as the sum of a steady-state component Pload_dc and a pulsating component Pload_fluctuate. Fig. 4 shows the power input to the air conditioner 60 when the load torque fluctuates at a fundamental frequency of 20 Hz and vibration suppression control is performed to control the output torque of the rotating electric machine in accordance with the fluctuations in the load torque.

[0036] An example of control of the DC / DC converter by the control device 80 will be described with reference to Figures 5 and 6. For simplicity, the description will be given here of a case where the power system 1 does not include the storage battery 50 and the DC / DC converter 51. In this example, the control device 80 controls the power output by the DC / DC converter 41, and voltage fluctuations in the DC line are suppressed.

[0037] Fig. 5 shows power waveforms in the power system 1 when the control device 80 does not control the power output by the DC / DC converter 41. Fig. 5(a) shows an example where the power consumption of the air conditioner 60 is constant, and Fig. 5(b) shows an example where the power consumption of the air conditioner 60 pulsates. The vertical axis represents power (W) and the horizontal axis represents time (sec). 5, the power Ppv output by the DC / DC converter 41 is shown by a solid line. The power Ppcs input to the grid-connected inverter 10 is shown by a dashed-dotted line. The power PC supplied to the capacitor 30 is shown by a two-dot chain line. The power Pload input to the air conditioner 60 is shown by a dashed line.

[0038] The power system 1 is connected to a three-phase AC power supply 100, and the input power Ppcs to the DC line side of the grid-connected inverter 10 is constant. The power Ppcs input to the grid-connected inverter 10 is controlled so that it becomes the DC component of the difference between the power Ppv output by the DC / DC converter 41 and the power Pload input to the air conditioner 60.

[0039] 5(a), when the power consumption Pload of the air conditioner 60 is constant, the power PC supplied to the capacitor 30 is always 0 W. In the example shown in FIG. 5(a), the power Ppv is 1500 W, the power Pload is constant at 500 W, and the power Ppcs is constant at 1000 W. On the other hand, when the power consumption Pload of the air conditioner 60 pulsates, a power pulsation that is opposite in phase to the power pulsation of the power Pload occurs in the power PC supplied to the capacitor 30, as shown in Figure 5(b). The power pulsation of the power PC supplied to the capacitor 30 causes pulsation in the capacitor voltage and reduces the life of the capacitor 30.

[0040] 6 is a diagram showing an example of a power waveform in the power system 1 when the control device 80 controls the power output by the DC / DC converter 41. The vertical axis represents power (W) and the horizontal axis represents time (sec). 6, the power Ppv output by the DC / DC converter 41 is shown by a solid line. The power Ppcs input to the grid-connected inverter 10 is shown by a dashed-dotted line. The power PC supplied to the capacitor 30 is shown by a two-dot chain line. The power Pload input to the air conditioner 60 is shown by a dashed line.

[0041] The control device 80 controls the power output by the DC / DC converter 41 so that the power Ppv supplied to the DC line by the DC / DC converter 41 includes the power pulsation of the power consumption Pload of the air conditioner 60. As a result, as shown in Fig. 6, the input power PC to the capacitor 30 is always 0 W, thereby suppressing voltage fluctuations on the DC line and shortening the life of the capacitor 30.

[0042] When the storage battery 50 and the DC / DC converter 51 are provided, the configuration may be such that it is possible to select which DC / DC converter is used to compensate for power pulsation in the power consumption Pload of the air conditioner 60. Furthermore, when multiple DC / DC converters are provided, the configuration may be such that power pulsation is compensated for by one DC / DC converter, or may be such that power pulsation is compensated for by multiple DC / DC converters.

[0043] (Second embodiment) 7 is a diagram showing an example of the configuration of a power system 2 to which a control device 80 according to the second embodiment is applied. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals. The power system 2 includes a grid-connected inverter 10, a DC link unit 20, a capacitor 30, a solar panel 40, a storage battery 50, an air conditioner 60, a detection circuit 70, and a control device 80. The power system 2 differs from the power system 1 in that the power system 2 is connected to a single-phase AC power supply 200 via the grid-connected inverter 10. The single-phase AC power supply 200 is an example of a grid power supply. The grid-connected inverter 10 is configured, for example, with a full-bridge circuit in which four transistors are arranged in a bridge shape.

[0044] An example of control of the DC / DC converter by the control device 80 will be described with reference to Figures 8 and 9. For simplicity, the following description will be given of a case where the power system 2 does not include the storage battery 50 and the DC / DC converter 51. In this example, the control device 80 controls the power output by the DC / DC converter 41, thereby suppressing voltage fluctuations in the DC line.

[0045] 8A and 8B are diagrams showing power waveforms in the power system 2 when the control device 80 does not control the power output by the DC / DC converter 41. (a) shows an example where the power consumption of the air conditioner 60 is constant, and (b) shows an example where the power consumption of the air conditioner 60 pulsates. The vertical axis represents power (W) and the horizontal axis represents time (sec). 8, the power Ppv output by the DC / DC converter 41 is shown by a solid line. The power Ppcs input to the grid-connected inverter 10 is shown by a dashed-dotted line. The power PC supplied to the capacitor 30 is shown by a two-dot chain line. The power Pload input to the air conditioner 60 is shown by a dashed line.

[0046] The DC component of the power Ppcs input to the grid-connected inverter 10 is controlled to be the DC component of the difference between the power Ppv output by the DC / DC converter 41 and the power Pload input to the air conditioner 60. The power system 2 is connected to a single-phase AC power supply 200, and the input power Ppcs on the DC line side of the grid-connected inverter 10 pulsates at a frequency twice the power supply frequency of the single-phase AC power supply 200. Here, the power supply frequency of the single-phase AC power supply 200 is assumed to be 50 Hz. In this case, the input power Ppcs pulsates at a frequency of 100 Hz.

[0047] As shown in FIG. 8(a), when the power consumption Pload of the air conditioner 60 is constant, the power PC supplied to the capacitor 30 generates a power pulsation that is opposite in phase to the power pulsation of the power Ppcs. On the other hand, when the power consumption Pload of the air conditioner 60 pulsates, as shown in Figure 8(b), a power pulsation occurs in the power PC supplied to the capacitor 30, which is the sum of a power pulsation that is opposite in phase to the power pulsation of the power Pload and a power pulsation that is opposite in phase to the power pulsation of the power Ppcs.

[0048] 9 is a diagram showing an example of a power waveform in the power system 2 when the control device 80 controls the power output by the DC / DC converter 41. The vertical axis represents power (W), and the horizontal axis represents time (sec). The control device 80 controls the power output by the DC / DC converter 41 so that the power Ppv that the DC / DC converter 41 supplies to the DC line includes the power pulsation of the power consumption Pload of the air conditioner 60. As a result, as shown in Fig. 9, the pulsation component caused by the power pulsation of the power consumption Pload of the air conditioner 60 is removed from the input power PC to the capacitor 30, thereby suppressing voltage fluctuations on the DC line and shortening the life of the capacitor 30.

[0049] (Modification of the second embodiment) In power system 2, control device 80 may be configured to control the power output by DC / DC converter 41 so that the power pulsation of power Pload is included in the difference between power Ppv and power Ppcs. In other words, control device 80 may control the power output by DC / DC converter 41 so that both the power pulsation of power Pload and the power pulsation of power Ppcs are included in power Ppv.

[0050] 10 is a diagram showing an example of a power waveform in power system 2 when the power pulsation of power Pload is included in the difference between power Ppv and power Ppcs. The vertical axis represents power (W) and the horizontal axis represents time (sec). 10, the power Ppv supplied to the DC line by the DC / DC converter 41 includes both the power pulsation of the power Pload and the power pulsation of the power Ppcs, so that the power pulsation of the power PC input to the capacitor 30 becomes zero. This suppresses voltage fluctuations on the DC line and shortens the lifespan of the capacitor 30.

[0051] The power ripple component of the power Ppcs input to the grid-connected inverter 10 is estimated from, for example, the AC voltage, AC current, and phase output to the AC line by the grid-connected inverter 10. Alternatively, the power ripple component may be identified by providing a mechanism for measuring the output power of the grid-connected inverter 10 and performing frequency analysis on the measured output power.

[0052] (Modified DC / DC converter) As mentioned above, the DC / DC converter may include a power decoupling circuit, a series voltage injector circuit, and the like.

[0053] 11 is a diagram showing an example of a power decoupling circuit, which is a step-up active buffer circuit 101. The active buffer circuit 101 is connected in parallel to a DC power supply 110. The DC power supply 110 may be, for example, a solar panel or a storage battery. The active buffer circuit 101 includes a boost chopper 1011, a buffer capacitor 1012, and a filter capacitor 1013. The active buffer circuit 101 adjusts the voltage of the buffer capacitor 1012 to adjust pulsation in the DC power. The voltage of the buffer capacitor 1012 is adjusted by the boost chopper 1011. The filter capacitor 1013 filters ripple currents and the like generated in the grid-connected inverter 10 (see FIG. 1). The active buffer circuit 101 may be configured without the filter capacitor 1013.

[0054] 12 is a diagram showing another example of a power decoupling circuit, which is a step-down active buffer circuit 102. The active buffer circuit 102 is connected in parallel to the DC power supply 120. The DC power supply 120 may be, for example, a solar panel or a storage battery. The active buffer circuit 102 includes a step-down chopper 1021, a buffer capacitor 1022, and a filter capacitor 1023. The active buffer circuit 102 adjusts the voltage of the buffer capacitor 1022 to adjust pulsation in the DC power. The voltage of the buffer capacitor 1022 is adjusted by the step-down chopper 1021. The filter capacitor 1023 filters ripple currents and the like generated in the grid-connected inverter 10 (see FIG. 1). The active buffer circuit 102 may be configured without the filter capacitor 1023.

[0055] FIG. 13 is a diagram illustrating an example of a series voltage injector circuit. The series voltage injector circuit 103 is connected in series to a DC power supply 130. The DC power supply 130 may be, for example, a solar panel or a storage battery. The series voltage injector circuit 103 includes a capacitor 1031, an inductor 1032, a switch circuit 1033, and a buffer capacitor 1034. The series voltage injector circuit 103 adjusts the pulsation of the DC power by adjusting the voltage of the capacitor 1031 connected in series to the DC power supply 130. The voltage of the capacitor 1031 is adjusted by the switch circuit 1033. Note that although the inductor 1032 in FIG. 13 is connected to one end of the capacitor 1031, it may also be connected to the other end of the capacitor 1031. Alternatively, the inductor 1032 may be connected to one end of the capacitor 1031 and the other end of the capacitor 1031. The circuits shown in FIGS. 11 to 13 are merely examples, and the present invention is not limited to these.

[0056] The circuit configuration of the DC / DC converter may also include a step-down circuit, a step-up circuit, or a step-up / step-down circuit, and a power decoupling circuit, a series voltage injector circuit, etc. For example, the circuit configuration of the DC / DC converter may include a step-up circuit and a power decoupling circuit. For example, the circuit configuration of the DC / DC converter may include a step-up / step-down circuit and a series voltage injector circuit.

[0057] <Effects> The control device 80 of the present disclosure controls one or more converters that transmit a first DC power Ppv to a DC link unit 20, the first DC power Ppv including a first power pulsation that is an AC component, the DC link unit 20 being configured to transmit a second DC power Pload to an air conditioner 60 connected to the DC link unit 20, and the control device 80 includes a pulsation information acquisition unit 81 that acquires a second power pulsation that is an AC component included in the second DC power Pload, and adjusts the first power pulsation in accordance with the second power pulsation acquired by the pulsation information acquisition unit 81. In this case, it is possible to adjust the power pulsation of the DC link unit 20 that is caused by fluctuations in power consumption of the air conditioner 60 connected to the DC link unit 20. Here, the DC link unit 20 is configured to be able to transmit and receive third DC power PC to and from a capacitor 30 connected to the DC link unit 20, and the control device 80 adjusts the first power pulsation so as to reduce third power pulsation, which is an AC component included in the third DC power PC. In this case, it is possible to suppress a decrease in the life of the capacitor 30. Furthermore, the control device 80 of the present disclosure adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation, which makes it easier to adjust the power pulsation. Furthermore, the control device 80 of the present disclosure adjusts the first power pulsation so that it approaches the second power pulsation, thereby canceling out the power pulsation component. Furthermore, the DC link unit 20 is configured to be able to transmit and receive a fourth DC power Ppcs to and from a grid-connected inverter 10 connected to the DC link unit 20 and connected to a single-phase AC power supply 200, and the control device 80 adjusts the frequency component of the first power pulsation that is twice the frequency of the single-phase AC power supply 200 in accordance with a fourth power pulsation of the fourth DC power Ppcs that is a frequency component that is twice the frequency of the grid power supply. In this case, the power pulsation component generated in the grid-connected inverter 10 can be adjusted. At least one of the converters is connected to a power source and converts the power of the power source into the first DC power Ppv. In this case, it is possible to adjust power pulsation of the DC link unit 20 caused by fluctuations in power consumption of the air conditioner 60 connected to the DC link unit 20. Furthermore, the pulsation information acquisition unit 81 acquires information correlated with the second power pulsation from the air conditioner 60. In this case, the air conditioner 60 and the control device 80 can share the arithmetic processing. Furthermore, the pulsation information acquiring unit 81 acquires the second DC power Pload from the detecting circuit 70 that measures the second DC power Pload. In this case, even when a plurality of air conditioners 60 are provided, the second DC power Pload can be easily acquired. The air conditioner 60 includes a rotating electric machine, in which case power pulsation caused by the rotation of the rotating electric machine can be adjusted. Furthermore, the second power pulsation pulsates at an integral multiple of the rotational speed of the rotating electric machine, making it possible to adjust the power pulsation caused by the rotation of the rotating electric machine. Moreover, a power conditioner of the present disclosure includes a control device 80 according to any one of claims 1 to 10, one or more converters controlled by the control device 80, a DC link unit 20 to which the converter is connected and configured to be connectable to an air conditioner 60, and a grid-connected inverter 10 connected to the DC link unit 20 and configured to be connectable to a grid power supply. In this case, it is possible to adjust power pulsation in the DC link unit 20 caused by fluctuations in power consumption of the air conditioner 60 connected to the DC link unit 20. Furthermore, the heat pump system of the present disclosure includes a refrigeration device as the electric device in the power conditioner according to claim 11. In this case, it is possible to adjust power pulsation of the DC link unit 20 caused by fluctuations in power consumption of the electric device connected to the DC link unit 20. The air conditioner 60 according to the present disclosure is an air conditioner 60 connected to a DC link unit 20, the DC link unit 20 being controlled by a control device 80 and connected to one or more converters that transmit a first DC power Ppv to the DC link unit 20, the first DC power Ppv including a first power ripple that is an AC component, the DC link unit 20 being configured to transmit a second DC power Pload to the air conditioner 60, the control device 80 including a pulsation information acquisition unit 81 that acquires a second power ripple that is an AC component included in the second DC power Pload, and is configured to adjust the first power ripple in accordance with the second power ripple acquired by the pulsation information acquisition unit 81, and the air conditioner 60 including a communication unit that transmits information correlated with the second power ripple to the pulsation information acquisition unit 81. In this case, it is possible to adjust the power ripple of the DC link unit 20 that is caused by fluctuations in power consumption of the air conditioner 60 connected to the DC link unit 20. The air conditioner 60 of the present disclosure is a refrigeration device.

[0058] Although the embodiments have been described above, the technical scope of the present disclosure is not limited to the scope of the above-described embodiments. It is clear from the claims that combinations of two or more of the above-described embodiments, and various modifications or improvements to the above-described embodiments, are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0059] 10...Grid-connected inverter, 20...DC link unit, 30...Capacitor, 40...Solar panel, 50...Storage battery, 60...Air conditioner, 70...Detection circuit, 80...Control device, 100...Three-phase AC power supply, 200...Single-phase AC power supply

Claims

1. A control device that controls one or more converters that transmit first DC power to a DC link unit, the first DC power includes a first power ripple that is an AC component, the DC link unit is configured to be able to transmit second DC power to an electric device connected to the DC link unit; The control device a pulsation acquiring unit that acquires a second power pulsation that is an AC component included in the second DC power, adjusting the first power pulsation in accordance with the second power pulsation acquired by the pulsation acquisition unit; Control device.

2. the DC link unit is configured to be able to transmit and receive third DC power to and from a capacitor connected to the DC link unit; The control device according to claim 1 , wherein the control device adjusts the first power pulsation so as to reduce a third power pulsation, which is an AC component included in the third DC power.

3. The control device according to claim 1 , wherein the control device adjusts an amplitude difference and a phase difference between the second power pulsation and the first power pulsation.

4. The control device of claim 1 , wherein the control device adjusts the first power pulsation to approximate the second power pulsation.

5. the DC link unit is connected to the DC link unit and is configured to be able to transmit and receive fourth DC power to and from a grid-connected inverter that is connected to a single-phase grid power supply; 2. The control device according to claim 1, wherein the control device adjusts the frequency component of the first power pulsation that is twice the frequency of the grid power supply in accordance with a fourth power pulsation of the fourth DC power that is a frequency component that is twice the frequency of the grid power supply.

6. The control device according to claim 1 , wherein at least one of the converters is connected to a power source and converts power from the power source into the first DC power.

7. The control device according to claim 1 , wherein the pulsation acquisition unit acquires information correlated with the second power pulsation from the electric device.

8. The control device according to claim 1 , wherein the pulsation acquiring unit acquires the second DC power from a DC power measuring unit that measures the second DC power.

9. The control device according to claim 1 , wherein the electrical equipment includes a rotating electrical machine.

10. The control device according to claim 9 , wherein the second power pulsation pulsates at an integer multiple of the rotational speed of the rotating electric machine.

11. A control device according to any one of claims 1 to 10; one or more converters controlled by the controller; a DC link unit to which the converter is connected and to which an electric device can be connected; a grid-connected inverter connected to the DC link unit and configured to be able to be connected to a grid power supply; A power conditioner equipped with

12. The power conditioner according to claim 11, A heat pump system including a refrigeration device as the electrical equipment.

13. An electric device connected to a DC link unit, the DC link unit is controlled by a control device and connected to one or more converters that transmit first DC power to the DC link unit; the first DC power includes a first power ripple that is an AC component, the DC link unit is configured to be able to transmit second DC power to the electric device, The control device a pulsation acquiring unit that acquires a second power pulsation that is an AC component included in the second DC power, The power supply is configured to adjust the first power pulsation in accordance with the second power pulsation acquired by the pulsation acquisition unit, The electrical device includes a communication unit that transmits information correlated with the second power pulsation to the pulsation acquisition unit. Electrical equipment.

14. The electrical appliance according to claim 13, wherein the electrical appliance is a refrigeration device.

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