Power converters and outdoor units of air conditioners

Abstract

The present invention comprises: a converter (2) that rectifies an alternating-current voltage supplied from an alternating-current power source (1); an inverter (5) that converts the voltage rectified by the converter (2) into an alternating-current voltage and outputs the alternating-current voltage to a motor (6); a driving signal generation unit (7) that generates a driving signal and outputs the driving signal to the inverter (5); a first voltage detection unit (8) that detects a voltage of an input unit of the inverter (5); a zero cross detection unit (9) that detects at least one voltage zero cross point in power source wiring; a current detection unit (10) that detects a current value of alternating-current power supplied from the alternating-current power source (1); a power source voltage restoration unit (11) that restores information relating to an alternating-current amount of the alternating-current voltage supplied from the alternating-current power source (1) on the basis of the voltage zero cross point detected by the zero cross detection unit (9), and the voltage of the input unit of the inverter (5) detected by the first voltage detection unit (8); and a power calculation unit (12) that calculates input power input from the alternating-current power source (1) on the basis of the information relating to the alternating-current amount and the alternating-current value of the alternating-current power.

Description

Technical Field

[0001] The present disclosure relates to a power conversion device that rectifies AC power supplied from a commercial power source and then converts it into AC power for output, and an outdoor unit of an air conditioner equipped with the same.

Background Art

[0002] In a power conversion device that rectifies AC power supplied from a commercial power source and then converts it into AC power for output, as disclosed in Patent Document 1, the amplitude value of the phase voltage of the power source is obtained from the detected value of the bus voltage, and the input power is obtained based on the obtained phase voltage amplitude and the effective current component.

Prior Art Documents

Patent Documents

[0003] [[ID=2[1]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The power conversion device disclosed in Patent Document 1 obtains the input power from the amplitude value of the power source and the effective current, and since information related to the AC amount of the power supply voltage cannot be obtained, the accuracy of the input power decreases. In order to detect the AC amount of the power supply voltage, there is a problem that when a circuit for performing the detection is mounted, the substrate size and component cost for mounting increase.

[0005] The present disclosure has been made in view of the above, and an object thereof is to obtain a power conversion device that suppresses an increase in substrate size and component cost and can estimate input power with high accuracy.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the power conversion device according to this disclosure comprises a converter that rectifies AC power supplied from an AC power source, a main circuit capacitor that smooths the power rectified by the converter, a reactor provided between the converter and the main circuit capacitor, an inverter that converts the power rectified by the converter into AC power and outputs it to a motor, and a drive signal generation unit that generates a drive signal for driving the motor and outputs it to the inverter. The power conversion device comprises a first voltage detection unit that detects the voltage at the input of the inverter, a zero-crossing detection unit that detects at least one voltage zero-crossing point in the power wiring connecting the AC power source and the converter, a current detection unit that detects the current value of the AC power supplied from the AC power source, a power supply voltage restoration unit that restores information relating to the amount of AC power supplied from the AC power source based on the voltage zero-crossing point detected by the zero-crossing detection unit and the voltage at the input of the inverter detected by the first voltage detection unit, and a power calculation unit that calculates the input power input from the AC power source based on the information relating to the amount of AC power restored by the power supply voltage restoration unit and the current value of the AC power detected by the current detection unit. [Effects of the Invention]

[0007] The power conversion device described herein has the effect of suppressing increases in substrate size and component costs, while also being able to estimate input power with high accuracy. [Brief explanation of the drawing]

[0008] [Figure 1] Diagram showing the configuration of the power conversion device according to Embodiment 1. [Figure 2] This figure shows an example of a hardware configuration that realizes the control unit included in the power conversion device according to Embodiment 1. [Figure 3] This figure shows an example of the relationship between the power supply voltage waveform and the detection signal of the power conversion device according to Embodiment 1. [Figure 4] Diagram showing the configuration of the power converter according to Embodiment 2. [Figure 5] This figure shows an example of the relationship between the power supply voltage waveform and the detection signal of the power conversion device according to Embodiment 2. [Figure 6] Diagram showing the configuration of the power converter according to Embodiment 3. [Figure 7] This figure shows the power supply voltage and rectifier circuit output voltage when a three-phase power supply imbalance occurs in the power converter according to Embodiment 3. [Figure 8] Diagram showing the configuration of the power converter according to Embodiment 4. [Figure 9] Diagram showing the configuration of the power converter according to Embodiment 5. [Figure 10] Diagram showing the configuration of the power converter according to Embodiment 6. [Figure 11] Diagram showing the configuration of the outdoor unit of the air conditioner according to Embodiment 7. [Figure 12] This diagram shows the configuration of the power conversion device included in the outdoor unit of the air conditioner according to Embodiment 7. [Modes for carrying out the invention]

[0009] The power conversion device and the outdoor unit of the air conditioner according to the embodiment will be described in detail below with reference to the drawings.

[0010] Embodiment 1. Figure 1 shows the configuration of a power conversion device according to Embodiment 1. The power conversion device 100 according to Embodiment 1 includes a converter 2 that rectifies the AC voltage supplied from an AC power source 1, a main circuit capacitor 4 that smooths the rectified voltage, a reactor 3 provided between the converter 2 and the main circuit capacitor 4, an inverter 5 that converts the smoothed rectified voltage into an AC voltage and outputs it to a motor 6, a drive signal generation unit 7 that generates and sends a drive signal to the inverter 5 to drive the motor 6, a first voltage detection unit 8 that detects the voltage Vdc at the input of the inverter 5, a zero-crossing detection unit 9 that detects a zero-crossing point of voltage between at least one phase, and a current detection unit 10 that detects the current value of the AC power. Either an electrolytic capacitor or a film capacitor may be used for the main circuit capacitor 4.

[0011] The drive signal generation unit 7 generates a drive signal for controlling the power conversion operation by the inverter 5 based on a voltage command (not shown) input from the outside, and sends it to the inverter 5. The drive signal generation unit 7 generates a drive signal using a known general method. Since the voltage output from the inverter 5 to the motor 6 depends on the voltage Vdc at the input section of the inverter 5, the drive signal may be generated based on the information on the voltage Vdc at the input section of the inverter 5 detected by the first voltage detection unit 8.

[0012] Also, the power conversion device 100 includes a power supply voltage restoration unit 11 that restores information related to the alternating current amount of the power supply voltage based on the voltage zero-crossing point detected by the zero-crossing detection unit 9 and the voltage detection value detected by the first voltage detection unit 8, and a power calculation unit 12 that calculates the input power based on the restored power supply voltage and the current detection value detected by the current detection unit  10. Here, the "alternating current amount" is a value indicating the characteristics of the waveform of the alternating current voltage, and includes the amplitude and phase of the alternating current voltage.

[0013] The zero-crossing detection unit 9 detects that the power supply voltage supplied from the alternating current power supply 1 has passed through the voltage zero-crossing point, and outputs a detection signal ZC to the power supply voltage restoration unit 11.

[0014] The drive signal generation unit 7, the power supply voltage restoration unit 11, and the power calculation unit 12 are provided in the control unit 400. FIG. 2 is a diagram showing an example of the hardware configuration for realizing the control unit included in the power conversion device according to Embodiment 1. The control unit 400 is realized by a processor 91 that executes various processes, a memory 92 that is a main memory, and a storage device 93 that stores information.

[0015] The processor 91 may be an arithmetic means such as an arithmetic unit, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Also, the memory 92 may use a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory). The storage device 93 stores a program for executing the capacitor load suppression control process. The processor 91 reads out and executes the program stored in the storage device 93 in the memory 92. By the processor 91 reading out and executing the program stored in the storage device 93 in the memory 92, the functions of the control unit 400 are realized.

[0016] Note that the drive signal generation unit 7, the power supply voltage restoration unit 11, and the power calculation unit 12 may be realized by the functions of a common processor 91, or may be realized by the functions of separate processors 91, respectively.

[0017] FIG. 3 is a diagram showing an example of the relationship between the power supply voltage waveform and the detection signal of the power conversion device according to Embodiment 1. When the power supply voltage waveform passes through the voltage zero-crossing point, the zero-crossing detection unit 9 outputs a high-level detection signal ZC to the power supply voltage restoration unit 11, and outputs a low-level detection signal ZC to the power supply voltage restoration unit 11 when passing through the next voltage zero-crossing point. Then, the output level of the signal is repeatedly switched between high level and low level at the timing when the power supply voltage passes through the voltage zero-crossing point, such that a high-level detection signal ZC is output again when passing through the next voltage zero point.

[0018] Figure 3 shows a configuration in which a high-level detection signal ZC is output when the power supply voltage is positive and a low-level detection signal ZC is output when the power supply voltage is negative. However, the system is not limited to this example; a configuration in which a low-level detection signal ZC is output when the power supply voltage is positive and a high-level detection signal ZC is output when the voltage is negative is also possible.

[0019] The power supply voltage restoration unit 11 determines the phase and amplitude of the power supply voltage and restores the power supply voltage waveform based on the determined phase and amplitude. In other words, the power supply voltage restoration unit 11 restores the phase, restores the amplitude, and restores the power supply voltage waveform.

[0020] First, let's explain the phase restoration. The power supply voltage restoration unit 11 represents the power supply voltage phase by setting the timing when the detection signal ZC changes from a low level to a high level as 0 [rad], the timing when it changes from a high level to a low level as π [rad], and one period as 2π [rad]. It counts the elapsed time t [s] from the timing when the power supply voltage passes the voltage zero-crossing point, calculates the power supply voltage phase from the elapsed time, and generates a sinusoidal signal X synchronized with the calculated power supply voltage phase.

[0021] When the power supply voltage phase is θac [rad], the power supply voltage frequency is ωac [rad / s], and the elapsed time from the timing when the detection signal ZC changes from a low level to a high level is t [s], the power supply voltage restoration unit 11 calculates the power supply voltage phase from the relationship θac = ωac·t. Although the power supply voltage frequency is generally constant based on the power supply specifications, if the power supply is unstable, frequency fluctuations occur and the power supply voltage is no longer supplied at a uniform power supply voltage frequency ωac. For this reason, the power supply voltage restoration unit 11 may count the time from the timing when the power supply voltage crosses the zero-cross point to the next time the same timing occurs, and adjust the power supply voltage frequency ωac as appropriate. In this way, the power supply voltage restoration unit 11 generates a sine wave signal X = sin(θac) based on the calculated power supply voltage phase θac.

[0022] Next, the amplitude restoration will be explained. Assuming that a single-phase full-wave rectifier circuit is used in converter 2 and that the voltage drop across reactor 3 is small, the relationship between the average value of the input voltage Vdc of inverter 5 detected by the first voltage detection unit 8, which detects the input voltage of inverter 5, and the amplitude Vamp of the power supply voltage is Vamp = (π / 2)Vdc.

[0023] Furthermore, if the capacitance of the main circuit capacitor 4 is small and the pulsation of the detected value of Vdc is large, the system may be configured to include a filter, either in hardware or software, that smooths the pulsation of the detected value. An example of software that implements a filter to smooth the pulsation of the detected value is software that performs filtering operations such as averaging.

[0024] In the example above, we described the case where a single-phase full-wave rectifier circuit is used for converter 2. However, converter 2 may also use a rectifier circuit other than a full-wave rectifier circuit, a power factor correction circuit, or a boost circuit. In this case, the calculation formula used for amplitude restoration will differ from the formula above, but it will still be possible to restore the amplitude in a similar manner.

[0025] Next, the restoration of the power supply voltage waveform will be explained. The power supply voltage restoration unit 11 calculates the power supply voltage Vac using Vac = (π / 2)Vdc·sin(θac) based on the restoration results of the sinusoidal signal X and amplitude Vamp, and restores the power supply voltage waveform.

[0026] The power calculation unit 12 calculates the input power P based on the current value of the AC power detected by the current detection unit 10 and the restored power supply voltage Vac. The power calculation unit 12 uses the instantaneous value Ia of the single-phase AC power current to calculate the input power P using the formula P = Vac·Ia.

[0027] The power converter 100 according to Embodiment 1 can detect information related to the AC amount of the power supply voltage, which is necessary for calculating the input power of the power converter 100, without providing a direct detection means such as a power supply voltage sensor. In particular, the zero-cross detection unit 9 is a simple circuit composed of electronic components mounted on a circuit board, and can be constructed inexpensively with a small footprint on the board. Therefore, it can be made smaller and less expensive compared to a power converter that directly detects the power supply voltage using a power supply voltage sensor.

[0028] Although the power converter 100 shown in Figure 1 has a DC reactor 3 on the busbar, it may also be configured with an AC reactor on the power wiring between the AC power source 1 and the converter 2.

[0029] Embodiment 2. Figure 4 shows the configuration of the power converter according to Embodiment 2. The power converter 100a according to Embodiment 2 receives power from a three-phase AC power supply 1a. The three-phase AC power supply 1a and the converter 2a are connected by power wiring for the R phase, T phase, and S phase. The current detection unit 10a detects the current values ​​of the R phase and the S phase. The power calculation unit 12a receives the instantaneous value Ir of the R phase current and the instantaneous value Is of the S phase current as input.

[0030] The zero-cross detection unit 9 detects zero-crossing points of voltage between at least one phase. Here, it is assumed that the zero-crossing point of Vst, which is the line voltage between the S-phase voltage Vs and the T-phase voltage Vt, and the zero-crossing point of Vst, which is the line voltage between the R-phase voltage Vr and the t-phase voltage Vt, are detected. In the following description, the zero-cross detection unit 9 will be described as detecting the zero-crossing point of Vst, which is the line voltage between the S-phase voltage Vs and the T-phase voltage Vt, among the R-phase, S-phase, and T-phase of the power supply, but the line voltage Vst between the R-phase voltage Vr and the t-phase voltage Vt is detected in the same way.

[0031] Figure 5 shows an example of the relationship between the power supply voltage waveform and the detection signal of the power converter according to Embodiment 2. The zero-cross detection unit 9 outputs a high-level detection signal ZC to the power supply voltage restoration unit 11 when the voltage waveform of the line voltage Vst between the S phase and the T phase passes through a voltage zero-cross point, and outputs a low-level detection signal ZC to the power supply voltage restoration unit 11 when it passes through the next voltage zero point. Then, it outputs a high-level detection signal ZC again when it passes through the next voltage zero point, and so on, repeatedly switching the signal output level between high and low levels at the timing when the voltage waveform of the line voltage Vst between the S phase and the T phase passes through a voltage zero-cross point.

[0032] Figure 5 shows a configuration in which a high-level detection signal ZC is output during periods when the line voltage Vst between the S-phase and T-phase is positive, and a low-level detection signal ZC is output during periods when the line voltage Vst between the S-phase and T-phase is negative. However, the system is not limited to this example; a configuration in which a low-level detection signal ZC is output during periods when the line voltage Vst between the S-phase and T-phase is positive, and a high-level detection signal ZC is output during periods when it is negative, is also possible.

[0033] Assuming that a three-phase full-wave rectifier circuit is used in converter 2a and that the voltage drop across reactor 3 is small, the power supply voltage restoration unit 11 calculates the amplitude Vamp of the power supply voltage using the average value of the voltage Vdc detected by the first voltage detection unit 8, which detects the voltage at the input of inverter 5, as Vamp = (π / 3)Vdc. As described later, for the purpose of calculating the input power using Blondel's theorem, the power supply voltage restoration unit 11 restores 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. Note that calculation methods other than Blondel's theorem may be used in the input power calculation.

[0034] The power calculation unit 12a uses the instantaneous value Ir of the R-phase current and the instantaneous value Is of the S-phase current to calculate the input power P using the formula P = Vac(st)·Ir + Vac(tr)·Is.

[0035] In the above description, we showed a case where the current detection unit 10a detects the currents of two phases and the zero-crossing detection unit 9 detects one zero-crossing point. However, by increasing the number of phases for current detection or the number of zero-crossing point detection locations, it is possible to determine the power while considering the variation in each phase. Furthermore, in detecting the current value of AC power and the voltage zero-crossing point of AC voltage, detection may be performed at multiple points, and the input power may be calculated by restoring these points, rather than being limited to this embodiment. Also, in the case of a three-phase power supply, the selection of detection phases is not limited to the selected phases described above.

[0036] The power converter 100a according to Embodiment 2 can detect information related to the AC amount of the power supply voltage of the three-phase AC power supply 1a, which is necessary for calculating the input power of the power converter 100a, without providing any direct detection means such as a power supply voltage sensor.

[0037] Embodiment 3. Figure 6 shows the configuration of the power converter according to Embodiment 3. In the power converter 100b according to Embodiment 3, the power supply voltage restoration unit 11a determines whether or not a voltage imbalance occurs in the R phase, S phase, and T phase voltages supplied from the three-phase AC power supply 1a. If the power supply voltage restoration unit 11a determines that a voltage imbalance has occurred, it notifies the drive signal generation unit 7a that a voltage imbalance has occurred. The drive signal generation unit 7a, notified that a voltage imbalance has occurred, generates a drive signal to suppress the output of the inverter 5. Otherwise, it is the same as the power converter 100a according to Embodiment 2.

[0038] Figure 7 shows the power supply voltage and rectifier circuit output voltage of the power converter according to Embodiment 3 when a three-phase power supply imbalance occurs. Vr is the voltage of the R phase, Vs is the voltage of the S phase, and Vt is the voltage of the T phase. Figure 7 is an example where the amplitude of the S phase is small compared to the amplitudes of the R phase and T phase. When converter 2a is a three-phase full-wave rectifier circuit, as shown in Figure 7, the output voltage of converter 2a is the difference voltage between the maximum and minimum values ​​of the voltages of each phase. The minimum voltage here is the voltage value with a negative sign and the largest absolute value. As shown in Figure 7, a maximum value appears in the output voltage of converter 2a every 1 / 6 of the power supply cycle. If the three-phase power supply is balanced, each maximum value will be the same, but in the example shown in Figure 7, the amplitude of the S phase is small compared to the amplitudes of the R phase and T phase, causing a voltage imbalance, so the maximum value fluctuates.

[0039] Assuming that the line voltage Vst between the S phase and the T phase is restored in the power supply voltage restoration unit 11a, the above maximum values ​​appear when the phase [rad] of Vst is π / 6, π / 2, 5π / 6, 7π / 6, 2π / 3, and 11π / 6, as shown in Figure 7. Therefore, the first voltage detection unit 8 detects the instantaneous voltage value when the phase of the restored line voltage Vrs between the R phase and the S phase matches the phase of these values, and if there is variation in the voltage for each detection, it is determined that a voltage imbalance has occurred. That is, if the difference between the maximum and minimum values ​​among the maximum values ​​detected by the first voltage detection unit 8 exceeds a predetermined value, it is determined that a voltage imbalance has occurred.

[0040] Furthermore, the determination of voltage imbalance is not limited to the maximum value that occurs every 1 / 6 of the power supply cycle, but may also be based on the minimum value that occurs every 1 / 6 of the power supply cycle and appears when the phase [rad] of Vst is 0, π / 3, 2π / 3, π, 4π / 3, and 5π / 3.

[0041] In suppressing the output of inverter 5, the drive signal generation unit 7a generates a drive signal that reduces the output current of inverter 5, i.e., the current of motor 6. Alternatively, in suppressing the output of inverter 5, the drive signal generation unit 7a generates a drive signal that reduces the frequency of the output voltage of inverter 5, i.e., the rotational speed of motor 6.

[0042] When voltage imbalance occurs, the fluctuation range of the output voltage of converter 2a increases, which in turn increases the instantaneous maximum value of the current, causing an overcurrent. However, the power converter 100b according to Embodiment 3 can suppress the output of inverter 5, thereby reducing the current flowing from converter 2a to inverter 5 and suppressing damage to each component of the power converter 100b due to overcurrent.

[0043] Embodiment 4. Figure 8 shows the configuration of the power converter according to Embodiment 4. The power converter 100c according to Embodiment 4 differs from the power converter 100 according to Embodiment 1 in that it has a display unit 13 that displays an index value correlated with power based on the calculated value of the power calculation unit 12.

[0044] The display unit 13 displays an index value correlated with the input power based on the calculated value from the power calculation unit 12. The display unit 13 may be a monitor built into the power converter 100c. Alternatively, the display unit 13 may be a terminal such as a personal computer for operating and monitoring the status of the power converter 100c via wired communication, or it may be a remote controller or portable terminal for operating and monitoring the status of the power converter 100c via wireless communication.

[0045] The index values ​​correlated with power are, for example, the instantaneous power of the motor 6 during operation, which is sequentially calculated in the power calculation unit 12, or the cumulative power value obtained by sequentially adding the calculated power values. They also include indicators that use power information in their calculations, such as the power rate conversion value described later, and the annual performance factor (APF), which is a well-known indicator for air conditioners. Furthermore, if the value changes over time, it is also acceptable to perform an averaging process over a predetermined period and display the averaged value.

[0046] The power converter 100c according to Embodiment 4 displays an index value correlated with power, allowing the user to determine an appropriate balance between the function currently performed by a device such as an air conditioner into which the power converter 100c is incorporated and the index value correlated with power, and enabling the user to provide feedback on the operation of the device.

[0047] Embodiment 5. Figure 9 shows the configuration of the power converter according to Embodiment 5. The power converter 100d according to Embodiment 5 differs from the power converter 100 according to Embodiment 1 in that it has a data storage unit 14 that stores and holds index values ​​correlated with power based on the calculated values ​​of the power calculation unit 12.

[0048] Among the index values ​​correlated with power calculated based on the power calculation unit 12, some can be calculated and updated sequentially, such as instantaneous power consumption during operation. However, some index values ​​require calculation using the history of past motor 6 driving conditions or the history of power consumption over a defined period. For example, index values ​​such as the electricity rate conversion value for a certain period calculated from the power consumption history and the annual energy efficiency of the air conditioner require calculation using the history of power consumption over a defined period.

[0049] The data storage unit 14 stores the history of past motor 6 driving conditions and power history, which are necessary for calculating index values ​​correlated with power. The data storage unit 14 can be implemented using the memory function of a microcontroller. The memory function of the microcontroller that implements the data storage unit 14 may be provided by a microcontroller that implements the functions of the drive signal generation unit 7, power supply voltage restoration unit 11, and power calculation unit 12, or it may be provided by a microcontroller different from the one that implements the functions of the drive signal generation unit 7, power supply voltage restoration unit 11, and power calculation unit 12.

[0050] The power conversion device 100d according to Embodiment 5 can calculate an index value correlated with power, which is calculated from a history of power consumption, such as the equivalent value of electricity charges over a certain period, and can therefore provide the user with useful information related to power.

[0051] Embodiment 6. Figure 10 shows the configuration of the power converter according to Embodiment 6. The power converter 100e according to Embodiment 6 differs from the power converter 100 according to Embodiment 1 in that it includes a second voltage detection unit 15 for detecting the voltage of the reactor 3.

[0052] The power supply voltage restoration unit 11b restores information related to the AC amount of the power supply voltage based on the voltage zero-crossing point detected by the zero-crossing detection unit 9, the voltage detected by the first voltage detection unit 8, and the voltage detected by the second voltage detection unit 15.

[0053] In Embodiment 1, it was assumed that the voltage drop across reactor 3 was small. However, when a reactor 3 with a large capacitance is used for power supply harmonic countermeasures, the magnitude of the DC component of the voltage drop generated across reactor 3, mainly due to winding resistance, becomes significant. As a result, the restoration accuracy of the power supply voltage restoration unit 11b is affected. For this reason, the power converter 100e according to Embodiment 6 includes a second voltage detection unit 15 that detects the voltage VL across reactor 3 in order to take the voltage drop across reactor 3 into consideration in power calculations.

[0054] In amplitude restoration, in the power converter 100 according to Embodiment 1, the amplitude Vamp of the power supply voltage was determined from the voltage Vdc detected by the first voltage detection unit 8. However, in the power converter 100e according to Embodiment 6, the amplitude Vamp of the power supply voltage is determined based on the value obtained by adding the DC component of the voltage VL of the reactor 3 to the voltage Vdc detected by the first voltage detection unit 8, taking into consideration the magnitude of the DC component of the voltage drop across the winding resistance. Alternatively, a current detection means (not shown) may be newly provided to detect the current flowing through the reactor 3, and the power generated by the reactor 3 may be calculated based on the voltage VL and current of the reactor 3. The power calculated by the power calculation unit 12 described above, plus the power generated by the reactor 3, may be used as the input power.

[0055] When realizing the second voltage detection unit 15, it becomes necessary to use a sensor to detect the power supply voltage. However, since the voltage across the reactor 3 is small compared to the magnitude of the power supply voltage, it can be realized with a smaller and lower-cost sensor compared to a detection means for detecting the power supply voltage.

[0056] The power converter 100e according to Embodiment 6 takes into account the voltage drop generated by the reactor 3 when restoring information related to the AC amount of the power supply voltage, thereby improving the accuracy of restoring the AC amount and improving the accuracy of input power calculation.

[0057] Embodiment 7. Figure 11 is a diagram showing the configuration of the outdoor unit of an air conditioner according to Embodiment 7. The air conditioner 200 according to Embodiment 7 comprises an outdoor unit 120 and an indoor unit 130. The outdoor unit 120 comprises a power converter 100f, a compressor 60 driven by a motor, a fan 63, a fan motor 62 which is the 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 the refrigeration cycle 110. The compressor 60 comprises a 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 part of the refrigeration cycle 110.

[0058] The compressor motor 6a corresponds to motor 6 shown in Figure 1. Note that the refrigeration cycle 110 is not necessarily limited to the example configuration and may be other known configurations.

[0059] Figure 12 shows the configuration of the power conversion device provided in the outdoor unit of the air conditioner according to Embodiment 7. As shown in Figure 12, in the power conversion device 100f, the current detection unit 10 is provided on the AC power supply 1 side of the branch between the compressor 60 side and the fan drive unit 101 side. The current detection unit 10 detects the sum of the current flowing to the compressor 60 side and the current flowing to the fan drive unit 101 side, and the power calculated by the power calculation unit 12 includes the power used to drive the fan 63.

[0060] The power converter 100f according to Embodiment 7 can be made smaller and less expensive compared to a power converter that directly detects the power supply voltage using a power supply voltage sensor. Therefore, the outdoor unit 120 equipped with the power converter 100f can also be made smaller and less expensive.

[0061] The power converter 100f may also be provided with the display unit 13 shown in Embodiment 4. Alternatively, the air conditioner 200 may also be provided with the display unit 13.

[0062] The configurations shown in the above embodiments are merely examples of the content, and can be combined with other known technologies. It is also possible to omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of symbols]

[0063] 1 AC power supply, 1a Three-phase AC power supply, 2,2a Converter, 3 Reactor, 4 Main circuit capacitor, 5 Inverter, 6 Motor, 6a Compressor motor, 7,7a Drive signal generation unit, 8 First voltage detection unit, 9 Zero-crossing detection unit, 10,10a Current detection unit, 11,11a,11b Power supply voltage restoration unit, 12,12a Power calculation unit, 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, 93 Storage device, 100,100a,100b,100c,100d,100e,100f Power conversion device, 101 Fan drive device, 110 Refrigeration cycle, 120 Outdoor unit, 121 Four-way valve, 122 Heat source side heat exchanger, 130 Indoor unit, 131 Expansion device, 132 Load side heat exchanger, 200 Air conditioner, 400 Control unit.

Claims

1. A converter that rectifies AC power supplied from an AC power source, The main circuit capacitor smooths the power rectified by the converter, A reactor is provided between the converter and the main circuit capacitor, An inverter converts the power rectified by the converter into AC power and outputs it to the motor, A drive signal generation unit that generates a drive signal for driving the motor and outputs it to the inverter, A first voltage detection unit for detecting the voltage at the input section of the inverter, A zero-crossing detection unit for detecting at least one voltage zero-crossing point in the power wiring connecting the AC power supply and the converter, A current detection unit that detects the current value of the AC power supplied from the aforementioned AC power source, A power supply voltage restoration unit restores information relating to the amount of AC power supplied from the AC power supply based on the voltage zero-crossing point detected by the zero-crossing detection unit and the voltage of the inverter input detected by the first voltage detection unit. A power conversion device comprising a power calculation unit that calculates the input power input from the AC power source based on information relating to the amount of AC restored by the power supply voltage restoration unit and the current value of the AC power detected by the current detection unit.

2. The power conversion device according to claim 1, wherein the AC power supply is a three-phase AC power supply.

3. The power supply voltage restoration unit notifies the drive signal generation unit that a voltage imbalance has occurred between the phases of the three-phase AC, The power conversion device according to claim 2, wherein when the drive signal generation unit is notified by the power supply voltage restoration unit that a voltage imbalance has occurred between the phases of the three-phase AC, it outputs the drive signal to the inverter to suppress the output power of the inverter.

4. Equipped with a display unit that displays information, The power conversion device according to claim 1, wherein the power calculation unit calculates an index value correlated with the input power and displays the calculated index value on the display unit.

5. The system includes a data storage unit that stores the input power calculated by the power calculation unit, The power conversion device according to claim 1, wherein the power calculation unit calculates an index value correlated with the input power based on the historical data of the input power stored in the data storage unit.

6. The power conversion device according to claim 1, further comprising a second voltage detection unit for detecting the voltage of the reactor.

7. An outdoor unit of an air conditioner equipped with a power conversion device according to any one of claims 1 to 6.

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