Power conversion device and outdoor unit of an air conditioner

Abstract

A power conversion device comprising: a converter (2) for rectifying an alternating current supplied by an alternating current source (1); an inverter (5) for converting the voltage rectified by the converter into an alternating current power for output to a motor; a drive signal generation unit (7) for generating drive signals and outputting them to the inverter (5); a first voltage sensing unit (8) for sensing a voltage at an input part of the inverter; a zero-crossing sensing unit (9) for sensing at least one voltage zero crossing point on power lines; a current sensing unit (10) for sensing a current value of an alternating current power supplied by the alternating current source (1);a power source voltage reconstruction unit (11) for reconstructing information based on the voltage zero crossing point detected by the zero-crossing detection unit (9) and the voltage detected by the first voltage detection unit (8) at the input part of the inverter (5), wherein the information relates to AC quantities of the AC power supplied by the AC source (1); and a power calculation unit (12) for calculating an input power from the AC source (1) based on the information relating to the AC quantities and the current value of the AC current detected by the current detection unit.

Description

Technical field

[0001] The present disclosure relates to a power conversion device that rectifies alternating current power supplied by a mains power source and then converts it into alternating current power for output. The present disclosure also relates to an outdoor unit of an air conditioning system comprising the power conversion device. background

[0002] In a power conversion device that rectifies alternating current power supplied by a mains power source and subsequently converts it into alternating current power for output, as disclosed in patent literature 1, an amplitude value of a phase voltage of a power source voltage is determined from a detected bus voltage value, and the input power is determined on the basis of the determined amplitude of the phase voltage and an active current component. Citation list of patent literature

[0003] Patent literature 1: Japanese patent application, publication number 2009 - 089 469 Overview of the invention: The problem to be solved by the invention

[0004] The power conversion device disclosed in patent literature 1 determines the input power based on the amplitude of the power source and the active current, without obtaining information about the AC parameters of the power source voltage. This reduces the accuracy of the input power. Implementing a circuit that detects the AC parameters of the power source voltage increases the substrate size and component costs, which poses a problem.

[0005] The present disclosure was made in view of the foregoing, and one objective of the present disclosure is to obtain a power conversion device that is able to estimate the input power with higher accuracy while limiting the increase in the size of the substrate and the cost of the components. Means to solve the problem

[0006] To solve the aforementioned problem and achieve the objective, a power conversion device according to the present disclosure comprises: a converter for rectifying alternating current power supplied by an alternating current power source; a main circuit capacitor for smoothing the power rectified by the converter; an inductor arranged between the converter and the main circuit capacitor; an inverter for converting the power rectified by the converter into alternating current power for output to a motor; and A drive signal generation unit for generating drive signals to drive the motor and for outputting the drive signals to the inverter. The power conversion device further comprises: a first voltage sensing unit for detecting a voltage at an input part of the inverter; a zero-crossing detection unit for detecting at least one voltage zero crossing point on power lines connecting the AC power source and the converter; a current sensing unit for detecting a current value of an AC power supplied by the AC power source;a power source voltage reconstruction unit for reconstructing information based on the voltage zero-crossing point detected by the zero-crossing detection unit and the voltage detected by the first voltage detection unit at the input part of the inverter, wherein the information relates to AC quantities of the AC power supplied by the AC power source; and a power calculation unit for calculating an input power from the AC power source based on the information relating to the AC quantities reconstructed by the power source voltage reconstruction unit and the current value of the AC power detected by the current detection unit. Effects of the invention

[0007] The power conversion device according to the present disclosure has the effect of allowing the input power to be estimated with higher accuracy while limiting an increase in substrate size and component costs. Brief description of the drawings Fig. Figure 1 is a diagram showing a configuration of a power conversion device according to a first embodiment. Fig. Figure 2 is a diagram showing an exemplary configuration of hardware implementing a control unit of the power conversion device according to the first embodiment. Fig. Figure 3 is a diagram showing an exemplary relationship between a power source voltage waveform and a detection signal in the power conversion device according to the first embodiment. Fig. Figure 4 is a diagram showing a configuration of a power conversion device according to a second embodiment. Fig. Figure 5 is a diagram showing an exemplary relationship between a power source voltage waveform and a detection signal in the power conversion device according to the second embodiment. Fig. Figure 6 is a diagram showing a configuration of a power conversion device according to a third embodiment. Fig. Figure 7 is a diagram showing a power source voltage and an output voltage of a rectifier circuit in the power conversion device according to the third embodiment when there is an imbalance in a three-phase power source. Fig. Figure 8 is a diagram showing a configuration of a power conversion device according to a fourth embodiment. Fig. Figure 9 is a diagram showing a configuration of a power conversion device according to a fifth embodiment. Fig. Figure 10 is a diagram showing a configuration of a power conversion device according to a sixth embodiment. Fig. Figure 11 is a diagram showing a configuration of an outdoor unit of an air conditioner according to a seventh embodiment. Fig. Figure 12 is a diagram showing a configuration of a power conversion device included in the outdoor unit of the air conditioner according to the seventh embodiment. Description of the embodiments

[0008] With reference to the drawings, a detailed description of power conversion devices and an outdoor unit of an air conditioning system according to embodiments is provided below. First embodiment.

[0009] Fig. Figure 1 is a diagram showing a configuration of a power conversion device according to a first embodiment. The power conversion device 100 according to the first embodiment comprises a converter 2, an inductor 3, a main circuit capacitor 4, an inverter 5, a drive signal generation unit 7, a first voltage sensing unit 8, a zero-crossing sensing unit 9, and a current sensing unit 10. The converter 2 rectifies an alternating voltage supplied by an alternating current power source 1. The inductor 3 is provided between the converter 2 and the main circuit capacitor 4. The main circuit capacitor 4 smooths the rectified voltage. The inverter 5 converts the rectified and smoothed voltage into an alternating voltage, which is output to a motor 6. The drive signal generation unit 7 generates drive signals and sends them to the inverter 5 to drive the motor 6.The first voltage sensing unit 8 detects the voltage Vdc at an input of the inverter 5. The zero-crossing detection unit 9 detects at least one phase-to-phase voltage zero crossing point. The current sensing unit 10 detects a current value of the AC power. Either an electrolytic capacitor or a film capacitor can be used as the main circuit capacitor 4.

[0010] The drive signal generation unit 7 generates the drive signals for controlling the power conversion operation of the inverter 5 based on externally input voltage commands (not shown) and sends the drive signals to the inverter 5. The drive signal generation unit 7 generates the drive signals using a generally known and common method. The output voltage from the inverter 5 to the motor 6 depends on the voltage Vdc at the input part of the inverter 5; therefore, the drive signals can be generated based on information about the voltage Vdc, which is detected at the input part of the inverter 5 by the first voltage sensing unit 8.

[0011] The power conversion device 100 further comprises a power source voltage reconstruction unit 11 and a power calculation unit 12. Based on the voltage zero-crossing point detected by the zero-crossing detection unit 9 and a voltage sensing value detected by the first voltage sensing unit 8, the power source voltage reconstruction unit 11 reconstructs information relating to AC quantities of the power source voltage. The power calculation unit 12 calculates the input power based on a reconstructed power source voltage and the current sensing value detected by the current sensing unit 10. Here, the term "AC quantities" refers to values ​​representing waveform characteristics of the AC voltage, including the amplitude and phase of the AC voltage.

[0012] The zero-crossing detection unit 9 detects when the power source voltage supplied by the AC power source 1 passes through the voltage zero-crossing point and outputs a detection signal ZC to the power source voltage reconstruction unit 11.

[0013] The drive signal generation unit 7, the power source voltage reconstruction unit 11 and the power calculation unit 12 are provided in a control unit 400. Fig. Figure 2 is a diagram showing an exemplary hardware configuration implemented by the control unit of the power conversion device according to the first embodiment. The control unit 400 is implemented using a processor 91, which executes various processes, a memory 92 serving as main memory, and a storage device 93, which stores information.

[0014] The processor 91 can be an arithmetic unit, a microprocessor, a microcomputer, a central processing unit (CPU), or a digital signal processor (DSP). The memory 92 can be a non-volatile or volatile semiconductor memory, such as random-access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), or electrically erasable programmable read-only memory (EEPROM) (registered trademark). The memory device 93 stores a program for executing a capacitor charge reduction control process. The processor 91 reads programs stored in the memory device 93 into memory 92 to execute the programs. The processor 91 reads the programs stored in the memory device 93 into memory 92 and executes the programs, thereby implementing the functions of the control unit 400.

[0015] The drive signal generation unit 7, the power source voltage reconstruction unit 11 and the power calculation unit 12 can be implemented by a common function of the processor 91 or each by separate functions of the processor 91.

[0016] Fig. Figure 3 is a diagram illustrating an exemplary relationship between a power source voltage waveform and the detection signal at the power conversion device according to the first embodiment. The zero-crossing detection unit 9 outputs the detection signal ZC at a high level to the power source voltage reconstruction unit 11 when the power source voltage waveform passes through the voltage zero crossing point, and outputs the detection signal ZC at a low level to the power source voltage reconstruction unit 11 when the power source voltage waveform passes through a subsequent voltage zero crossing point.The zero-crossing detection unit 9 then outputs the detection signal ZC again at the high level when the power source voltage waveform passes through a subsequent voltage zero point, thus repeatedly switching the signal between the high and low output levels each time the power source voltage passes through a voltage zero-crossing point.

[0017] A in Fig. The mode shown in Figure 3 is such that the detection signal ZC is output at a high level while the power source voltage is positive, and at a low level while the power source voltage is negative; however, this example is not limited. The mode can be such that the detection signal ZC is output at a low level while the power source voltage is positive, and at a high level while the power source voltage is negative.

[0018] The power source voltage reconstruction unit 11 determines the phase and amplitude of the power source voltage and reconstructs the power source voltage waveform based on the determined phase and amplitude. In other words, the power source voltage reconstruction unit 11 reconstructs the phase, amplitude, and power source voltage waveform.

[0019] First, the phase reconstruction is described. The power source voltage reconstruction unit 11 expresses the power source voltage phase by defining the time at which the detection signal ZC transitions from the low level to the high level as 0 [rad], the time at which the detection signal ZC transitions from the high level to the low level as π [rad], and one cycle as 2π [rad]. The power source voltage reconstruction unit 11 counts the time t [s] elapsed since the power source voltage passed the voltage zero crossing point, calculates the power source voltage phase from the elapsed time, and generates a sine wave signal X synchronized with the calculated power source voltage phase.

[0020] The power source voltage reconstruction unit 11 determines the power source voltage phase using the relationship θac = ωac·t, where θac is the power source voltage phase [rad], ωac is the power source voltage frequency [rad / s], and t is the time elapsed since the detection signal ZC transitioned from a low level to a high level. Based on the power source determinations, the power source voltage frequency is generally constant. However, if the power supply is unstable, frequency fluctuations can occur, resulting in the power source voltage not being supplied with a uniform power source voltage frequency ωac. Accordingly, the power source voltage reconstruction unit 11 can count the time from when the power source voltage passes through the zero crossing point until the next such point and correct the power source voltage frequency ωac accordingly.Based on the power source voltage phase θac calculated in this way, the power source voltage reconstruction unit 11 generates the sine signal X=sin(θac).

[0021] Next, the amplitude reconstruction is described. Assuming that a single-phase full-wave rectifier circuit is used for the converter 2 and that the voltage drop across the choke 3 is small, a relationship arises between the mean value of the voltage Vdc, which is detected at the input point of the inverter 5 by the first voltage sensing unit 8, and the amplitude Vamp of the mains voltage, which is given by Vamp=(π / 2)Vdc.

[0022] If the capacitance of the main circuit capacitor 4 is small, resulting in significant pulsation of the Vdc measurement value, the configuration can include a filter, either hardware or software, to smooth the pulsation in the measurement value. An example of software that implements this smoothing filter is software that performs a filter operation, such as an averaging operation.

[0023] In the example described above, a single-phase full-wave rectifier circuit is used for converter 2; however, a different rectifier circuit than a full-wave rectifier circuit, a power factor correction circuit, or a boost converter can also be used for converter 2. In this case, the formula used in the amplitude reconstruction process differs from the formula above; however, the amplitude can be reconstructed in a similar way.

[0024] Next, the reconstruction of the power source voltage waveform is described. The power source voltage reconstruction unit 11 calculates the power source voltage Vac based on the sine signal X and the result of the amplitude reconstruction Vamp using Vac=(π / 2)Vdc·sin(θac) and thus reconstructs the power source voltage waveform.

[0025] The power calculation unit 12 calculates the input power P based on the current value of the AC power detected by the current sensing unit 10 and the reconstructed power source voltage Vac. The power calculation unit 12 calculates the input power P using P = Vac · Ia, where the instantaneous current value Ia of the single-phase AC power is used.

[0026] The power conversion device 100 according to the first embodiment can acquire the information relating to the AC parameters of the power source voltage, which is necessary for calculating the input power of the power conversion device 100, thus eliminating the need for a direct sensing device, such as a power source voltage sensor. In particular, the zero-crossing sensing unit 9 is a simple circuit comprising a substrate-mounted electronic component, requiring a small substrate area and allowing for cost-effective configuration. Therefore, the power conversion device 100 can be implemented in a smaller size and at a lower cost than a power conversion device configured to directly sense the power source voltage using a power source voltage sensor.

[0027] The in Fig. The power conversion device 100 shown has the choke 3 as a DC choke on a bus line; however, the power conversion device 100 can be configured with an AC choke provided on power lines between the AC power source 1 and the converter 2. Second embodiment

[0028] Fig. Figure 4 is a diagram showing a configuration of a power conversion device according to a second embodiment. The power conversion device 100a according to the second embodiment is supplied with power by a three-phase AC power source 1a. The three-phase AC power source 1a and a converter 2a are connected via an R-phase, a T-phase, and an S-phase line. A current sensing unit 10a detects the current values ​​of the R-phase and the S-phase. The instantaneous current value Ir of the R-phase and the instantaneous current value Is of the S-phase are input into a power calculation unit 12a.

[0029] The zero-crossing detection unit 9 detects at least one phase-to-phase voltage zero crossing point. The zero-crossing detection unit 9 is defined such that it detects a zero crossing point of the mains voltage Vst between the S-phase voltage Vs and the T-phase voltage Vt, and a zero crossing point of the mains voltage Vst between the R-phase voltage Vr and the t-phase voltage Vt. The following describes the zero-crossing detection unit 9, which detects the zero crossing point of the mains voltage Vst between the S-phase voltage Vs and the T-phase voltage Vt across phases R, S, and T of the power source. The same applies, however, to the detection of the mains voltage Vst between the R-phase voltage Vr and the t-phase voltage Vt.

[0030] Fig. Figure 5 is a diagram illustrating an exemplary relationship between a power source voltage waveform and a detection signal at the power conversion device according to the second embodiment. The zero-crossing detection unit 9 outputs the detection signal ZC at a high level to the power source voltage reconstruction unit 11 when a voltage waveform of the mains voltage Vst passes through the voltage zero crossing point between the S-phase and the T-phase, and outputs the detection signal ZC at a low level to the power source voltage reconstruction unit 11 when the voltage waveform passes through a subsequent voltage zero crossing point.The zero-crossing detection unit 9 then outputs the detection signal ZC again at the high level when the voltage waveform passes through a subsequent voltage zero point, thus repeatedly switching the signal between the high and low output levels each time the voltage waveform of the mains voltage Vst passes through a voltage zero-crossing point between the S-phase and the T-phase.

[0031] A in Fig. The mode shown in Figure 5 is such that the detection signal ZC is output at the high level while the voltage waveform of the mains voltage Vst between the S-phase and the T-phase is positive, and at the low level while the voltage waveform of the mains voltage Vst between the S-phase and the T-phase is negative; however, this example is not limiting. The mode can be such that the detection signal ZC is output at the low level while the voltage waveform of the mains voltage Vst between the S-phase and the T-phase is positive, and at the high level while the voltage waveform is negative.

[0032] Assuming that a three-phase full-wave rectifier circuit is used for the converter 2a and that the voltage drop in the inductor 3 is small, the power source voltage reconstruction unit 11 calculates the amplitude Vamp of the power source voltage using Vamp = (π / 3)Vdc, based on an average value of the voltage Vdc detected at the input point of the inverter 5 by the first voltage sensing unit 8. To calculate the input power using Blondel's theorem described later, the power source voltage reconstruction unit 11 reconstructs the line voltage Vac(st) between the S-phase and the T-phase and the line voltage Vac(tr) between the T-phase and the R-phase. The input power can also be calculated using a method other than Blondel's theorem.

[0033] The power calculation unit 12a calculates the input power P with P=Vac(st)·Ir+Vac(tr)·Is, where the instantaneous current value Ir of the R-phase and the instantaneous current value Is of the S-phase are used.

[0034] In the case described above, the current sensing unit 10a detects the currents of the two phases, and the zero-crossing sensing unit 9 detects the individual zero-crossing point. However, by detecting currents from an increased number of phases or an increased number of zero-crossing points, variations in each phase can be taken into account in the power calculation. Furthermore, the current values ​​of the AC power and the zero point of the AC voltage can be detected at multiple points, without being limited to the detections in this embodiment, and corresponding reconstructions for the input power to be calculated can be performed. For the three-phase power source, the phases to be detected are not limited to the previously selected phases.

[0035] The power conversion device 100a according to the second embodiment can acquire information relating to AC parameters of the power source voltage of the three-phase AC power source 1a, which are required to calculate the input power of the power conversion device 100a, thereby eliminating the need for a direct acquisition device, such as a power source voltage sensor. Third embodiment

[0036] Fig. Figure 6 is a diagram showing a configuration of a power conversion device according to a third embodiment. In the power conversion device 100b according to the third embodiment, a power source voltage reconstruction unit 11a determines whether a voltage imbalance has occurred between the R-phase, S-phase, and T-phase voltages supplied by the three-phase AC power source 1a. If the voltage imbalance is detected, the power source voltage reconstruction unit 11a reports the occurrence of the voltage imbalance to a drive signal generation unit 7a. When the drive signal generation unit 7a is informed of the occurrence of the voltage imbalance, it generates drive signals that reduce the power of the inverter 5. The power conversion device 100b is otherwise similar to the power conversion device 100a according to the second embodiment.

[0037] Fig. Figure 7 is a diagram showing a power source voltage and an output voltage of a rectifier circuit in the power conversion device according to the third embodiment with an imbalance in the three-phase power source. Vr represents the R-phase voltage, Vs represents the S-phase voltage, and Vt represents the T-phase voltage. In the example of Fig. 7. The amplitude of the S-phase is smaller than that of the R-phase and the T-phase. If the converter 2a is a three-phase full-wave rectifier circuit, as in Fig. Figure 7 shows a voltage difference between a maximum and a minimum value among the voltages of the phases relative to the output voltage of converter 2a. The minimum voltage value here refers to the negative voltage value, which is the largest absolute value. As shown in Fig. As shown in Figure 7, local maxima occur in the output voltage of converter 2a at intervals of 1 / 6 of a power supply cycle. If the three-phase power source is symmetrical, the local maxima are equal. In the Fig. However, in the example shown in Figure 7, the amplitude of the S-phase is small compared to the amplitudes of the R-phase and the T-phase, which leads to a voltage asymmetry that results in fluctuations of the local maximum.

[0038] When the mains voltage Vst between the S-phase and the T-phase is reconstructed by the power source voltage reconstruction unit 11a, as in Fig. As shown in Figure 7, the aforementioned local maxima occur when the phases [rad] of Vst are π / 6, π / 2, 5π / 6, 7π / 6, 2π / 3, and 11π / 6. The first voltage sensing unit 8 detects instantaneous voltage values ​​at which these phases coincide with the phases of the reconstructed values ​​Vac(rs) of the grid voltage Vrs between the R phase and the S phase. If the detected voltage fluctuates, a voltage imbalance is detected. In other words, a voltage imbalance is detected when the difference between the maximum and minimum values ​​among the local maximums detected by the first voltage sensing unit 8 exceeds a predetermined value.

[0039] The determination of whether a voltage imbalance has occurred can be based on local minima that similarly occur at intervals of 1 / 6 of the power supply cycle when the phase [rad] of Vst is 0, π / 3, 2π / 3, π, 4π / 3 and 5π / 3, without being limited to the local maxima that occur at intervals of 1 / 6 of the power supply cycle.

[0040] To reduce the output of inverter 5, the drive signal generation unit 7a generates drive signals that decrease the output current of inverter 5, i.e., the current in motor 6. Alternatively, to reduce the output of inverter 5, the drive signal generation unit 7a generates drive signals that decrease a frequency of the output voltage of inverter 5, namely the speed of motor 6.

[0041] In the presence of voltage imbalance, the output voltage of converter 2a fluctuates over a larger range, resulting in a maximum instantaneous current value and thus an overcurrent. However, the power conversion device 100b according to the third embodiment reduces the power output of inverter 5, thereby reducing the current flowing from converter 2a to inverter 5; therefore, the power conversion device 100b can prevent its components from being damaged by the overcurrent. Fourth embodiment

[0042] Fig. Figure 8 is a diagram showing a configuration of a power conversion device according to a fourth embodiment. The power conversion device 100c according to the fourth embodiment differs from the power conversion device 100 according to the first embodiment in that the power conversion device 100c includes a display unit 13 that displays an index value correlated with the power based on a calculated value of the power calculation unit 12.

[0043] The display unit 13 shows the index value correlated with the input power, based on the calculated value of the power calculation unit 12. The display unit 13 can be a monitor integrated into the power conversion device 100c. The display unit 13 can be a personal computer or other terminal device that monitors the operation and status of the power conversion device 100c via wired communication. The display unit 13 can be a remote control or portable terminal device that monitors the operation and status of the power conversion device 100c via wireless communication.

[0044] Examples of the power-correlated index value are the instantaneous power calculated sequentially by the power calculation unit 12 during the operation of the motor 6, and a cumulative power value obtained by sequentially adding the calculated power values, including indices calculated using power information such as an electricity tariff conversion value (described later) and an annual power factor (APF), which is a well-known index for air conditioners. For any values ​​that change over time, an average value can be displayed, obtained by averaging over a predetermined period.

[0045] The power conversion device 100c according to the fourth embodiment displays the index value correlated with the power, enabling a user to determine an appropriate balance between a function currently performed by a device with the power conversion device 100c, such as an air conditioner, and the index value correlated with the power, and to provide feedback on the operation of the device. Fifth embodiment

[0046] Fig. Figure 9 is a diagram showing a configuration of a power conversion device according to a fifth embodiment. The power conversion device 100d according to the fifth embodiment differs from the power conversion device 100 according to the first embodiment in that the power conversion device 100d includes a data storage unit 14 which stores and retains a power-correlated index value based on a calculated value of the power calculation unit 12.

[0047] Among the index values ​​that correlate with power and are calculated based on the calculated value of the power calculation unit 12, some index values, such as the instantaneous power consumed during operation, can be calculated and updated sequentially; however, some other indices must be calculated using a history of past operating conditions for motor 6 and a history of electricity consumption over a specific period. For example, an electricity tariff conversion value, calculated for a fixed period based on the consumption history and an annual power factor of an air conditioner, is among the index values ​​that must be calculated using the consumption history over the specified period.

[0048] The data storage unit 14 stores the history of past drive conditions for the motor 6 and the power history required for calculating the power-correlated index values. The data storage unit 14 can be implemented using a memory function of a microcontroller. The memory function of the microcontroller implementing the data storage unit 14 can be included in the same microcontroller that implements the drive signal generation unit 7, the power source voltage reconstruction unit 11, and the power calculation unit 12 functions described above, or it can be in a microcontroller different from the one implementing these functions.

[0049] The power conversion device 100d according to the fifth embodiment is able to calculate the index value that correlates with the power and is calculated on the basis of the consumption history, such as the electricity tariff conversion value for the specified period, and can therefore provide a user with useful power-related information. Sixth embodiment

[0050] Fig. Figure 10 is a diagram showing a configuration of a power conversion device according to a sixth embodiment. The power conversion device 100e according to the sixth embodiment differs from the power conversion device 100 according to the first embodiment in that the power conversion device 100e includes a second voltage sensing unit 15 that senses the voltage across the choke 3.

[0051] A power source voltage reconstruction unit 11b reconstructs information regarding the AC quantities of the power source voltage based on the voltage zero crossing point detected by the zero crossing detection unit 9, the voltage detection value detected by the first voltage detection unit 8, and a voltage detection value detected by the second voltage detection unit 15.

[0052] The first embodiment is based on the assumption that the voltage drop in the inductor 3 is small. However, if the inductor 3 used has a larger capacitance as a measure against current source harmonics, the magnitude of a DC component of the voltage drop, which occurs mainly due to the coil resistance in the inductor 3, can no longer be neglected. This impairs the reconstruction accuracy of the power source voltage reconstruction unit 11b. To take the voltage drop in the inductor 3 into account in the power calculation, the power conversion device 100e according to the sixth embodiment includes the second voltage sensing unit 15, which senses the voltage VL across the inductor 3. In amplitude reconstruction, the

[0053] According to the first embodiment, the power conversion device 100 determines the amplitude Vamp of the power source voltage from the voltage Vdc detected by the first voltage sensing unit 8. However, according to the sixth embodiment, the power conversion device 100e determines the amplitude Vamp of the power source voltage based on a value obtained by adding a DC component of the voltage VL across the inductor 3 to the voltage Vdc detected by the first voltage sensing unit 8, taking into account the magnitude of the DC component of the voltage drop due to the inductor resistance. A new current sensing means (not shown) may be provided to detect the current flowing through the inductor 3, and the power generated in the inductor 3 can be calculated based on the current and the voltage VL across the inductor 3.The input power can then be the sum of the power calculated by the power calculation unit 12 as described above and the power generated in the throttle 3.

[0054] To implement the second voltage sensing unit 15, a sensor or similar device that detects the power source voltage must be used. However, since the voltage across the choke 3 is lower than the power source voltage, a smaller and more cost-effective sensor can be used compared to a sensing device that detects the power source voltage.

[0055] The power conversion device 100e according to the sixth embodiment also takes into account the voltage drop that occurs in the inductor 3 when the information regarding the AC parameters of the power source voltage is reconstructed. Therefore, the AC parameters are reconstructed with improved accuracy, which in turn improves the accuracy of the input power calculation. Seventh embodiment

[0056] Fig. Figure 11 is a diagram showing a configuration of an outdoor unit of an air conditioner according to a seventh embodiment. The air conditioner 200 according to the seventh embodiment comprises the outdoor unit 120 and an indoor unit 130. The outdoor unit 120 comprises a power conversion device 100f; a compressor 60 which uses a motor as a drive source; a fan 63; a fan motor 62 which serves as a drive source for the fan 63; a fan drive device 101 which controls the fan 63; and a four-way valve 121 and a heat source-side heat exchanger 122, which are part of a refrigeration circuit 110. The compressor 60 comprises the compressor motor 6a and a compression element 61. The indoor unit 130 comprises an expansion device 131 and a load-side heat exchanger 132, which are parts of the refrigeration circuit 110.

[0057] The compressor motor 6a corresponds to the one in Fig. 1. Motor 6 shown. The refrigeration circuit 110 is not necessarily limited to the configuration shown and may have any other known configuration.

[0058] Fig. Figure 12 is a diagram showing a configuration of the power conversion device included in the outdoor unit of the air conditioner according to the seventh embodiment. As in Fig. As shown in Figure 12, the power conversion device 100f with the current sensing unit 10 is arranged closer to the AC power source 1 than the branches to the compressor 60 and the fan drive device 101, so that the current sensing unit 10 can detect the sum of the currents flowing to the compressor 60 and the fan drive device 101 to ensure that the power used to drive the fan 63 is included in the power calculated by the power calculation unit 12.

[0059] The power conversion device 100f according to the seventh embodiment can be implemented in a smaller size and at a lower cost than a power conversion device configured to directly detect the power source voltage by means of a power source voltage sensor. Therefore, the outdoor unit 120, which includes the power conversion device 100f, can also be implemented in a smaller size and at a lower cost.

[0060] The power conversion device 100f can be equipped with the display unit 13 described in the fourth embodiment. The display unit 13 can be provided in the air conditioning unit 200.

[0061] The configurations shown above in the embodiments serve to illustrate the content, can be combined with other prior art and can be partially omitted or modified without deviating from the core. Reference symbol list 1 AC power source; 1a three-phase alternating current power source; 2, 2a converter; 3. Throttle; 4 Main circuit capacitors; 5 inverters; 6 engine; 6a Compressor motor; 7, 7a Drive signal generation unit; 8 first voltage detection unit; 9 zero-crossing detection unit; 10, 10a Current sensing unit; 11, 11a, 11b Power source voltage reconstruction unit; 12, 12a Unit of performance calculation; 13 Display unit; 14 Data storage unit; 15 second voltage detection unit; 60 Compressor; 61 Compression element; 62 Fan motor; 63 Fan; 91 processor; 92 memory slots; 93 Storage device; 100, 100a, 100b, 100c, 100d, 100e, 100f Power conversion device; 101 Fan drive device; 110 Refrigeration circuit; 120 outdoor unit; 121 Four-way valve; 122 Heat exchanger on the heat source side; 130 indoor unit; 131 Expansion device; 132 load-side heat exchanger; 200 air conditioners; 400 control units. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2009 - 089 469

[0003]

Claims

[1] Power conversion device comprising: a converter for rectifying alternating current power supplied by an alternating current power source; a main circuit capacitor to smooth the power rectified by the converter; a choke provided between the converter and the main circuit capacitor; an inverter for converting the power rectified by the converter into alternating current power for output to a motor; a drive signal generation unit for generating drive signals to drive the motor and for outputting the drive signals to the inverter; a first voltage detection unit for detecting a voltage at an input part of the inverter; a zero-crossing detection unit for detecting at least one voltage zero-crossing point on power lines connecting the AC power source and the converter; a current sensing unit for recording the current value of an alternating current power supplied by the alternating current power source; a power source voltage reconstruction unit for reconstructing information based on the data from the zero-crossing detection unit detects voltage zero-crossing point and the voltage detected by the first voltage detection unit at the input part of the inverter, wherein the information relates to AC quantities of the AC power supplied by the AC power source; and a power calculation unit for calculating an input power from the AC power source based on the information relating to the AC quantities reconstructed by the power source voltage reconstruction unit, and the current value of the AC power detected by the current sensing unit. [2] Power conversion device according to claim 1, wherein the AC power source is a three-phase AC power source. [3] Power conversion device according to claim 2, wherein the power source voltage reconstruction unit informs the drive signal generation unit about the occurrence of a voltage imbalance between phases of a three-phase alternating current, and where, when the power source voltage reconstruction unit informs the drive signal generation unit about the occurrence of voltage imbalance between the phases of the three-phase alternating current, the drive signal generation unit outputs the drive signals to the inverter in order to reduce the output power of the inverter. [4] Power conversion device according to claim 1, comprising: a display unit for showing information, wherein the power calculation unit calculates an index value correlated with the input power and causes the display unit to display the calculated index value. [5] Power conversion device according to claim 1, comprising: a data storage unit for storing the input power calculated by the power calculation unit, wherein the power calculation unit calculates an index value correlated with the input power based on historical data about the input power stored in the data storage unit. [6] Power conversion device according to claim 1, comprising: a second voltage detection unit for detecting a voltage at the choke. [7] Outdoor unit of an air conditioning system, wherein the outdoor unit comprises the power conversion device according to any one of claims 1 to 6.

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