Power converter and air conditioning

Abstract

A power converter (100) comprises: a converter (2) that rectifies AC power; a first inverter (5a) and a second inverter (5b); a first voltage detection circuit (8a) that filters a detection value of a voltage input and outputs the detection value as a first voltage detection value; a second voltage detection circuit (8b) that filters a detection value of a voltage input and outputs the detection value as a second voltage detection value; first drive signal generation means (7a) that performs, based on the first voltage detection value, an operation of generating a drive signal for the first inverter and an operation of protecting the first inverter;and a second drive signal generating means (7b) that performs an operation of generating a drive signal for the second inverter and an operation of protecting the second inverter based on the second voltage detection value, wherein at least one of time constants of filter circuits and threshold values ​​is set based on wire impedances between the converter and the first inverter and between the converter and the second inverter, the filter circuits performing filtering in the first voltage detection circuit and the second voltage detection circuit, and the threshold values ​​are used in abnormality detection processes in the first drive signal generating means and the second drive signal generating means.;

Description

Area

[0001] The present disclosure relates to a power converter and an air conditioner. background

[0002] As a conventional power converter, there is a power converter with a plurality of power conversion circuits that convert power supplied from a common power source into a desired AC power and supply power. The power converter causes the power conversion circuits to generate the power required by a plurality of connected devices and supplies the generated power to the connected devices.

[0003] For example, Patent Literature 1 discloses a power converter (motor drive circuit) in which two inverters, that is, a first inverter and a second inverter, are connected to a rectifier circuit that rectifies an AC voltage of an AC power supply, and the first inverter and the second inverter generate drive voltages for driving a fan motor and a compressor motor, respectively. Citation listPatent literature

[0004] Patent Literature 1: Japanese Patent Application, Publication No. 2020-61913 Overview of the inventionProblem to be solved by the invention

[0005] In the case of the circuit configuration disclosed in Patent Literature 1, the two inverters are connected to a common bus. Therefore, voltages at the input sides of the two inverters are ideally equal. However, when there is a difference between the distances from an input bus to the inverters, there is also a difference between the impedances of the wires to the inverters. In particular, when the length of the bus between a converter (rectifier circuit) and an inverter increases due to limitations in arrangement within the device, the wire impedance further increases. Furthermore, the difference between the wire impedances increases when the distance to one inverter is greater than the distance to the other inverter.For example, when a motor drive circuit serving as a power converter as described in Patent Literature 1 is applied to an air conditioner, it is conceivable that a difference between a wire impedance of an electric circuit that supplies power to a motor of a compressor provided in an outdoor unit and a wire impedance of an electric circuit that supplies power to a motor of a blower provided in an indoor unit increases.

[0006] When the wire impedance increases, bus voltage fluctuations occur, such as a transient surge caused by a sudden change in the supply voltage or a sudden change in current associated with a sudden change in the motor load on one side. The higher the wire impedance, the greater the transient voltage fluctuation and the higher the risk of overvoltage. Therefore, higher overvoltage detection responsiveness is required to protect inverters. That is, when an overvoltage occurs, it must be detected early, and a protective circuit must quickly trigger a protective operation (protection function). When the wire impedance is low, the influence of ambient noise is greater than that of bus voltage fluctuations caused by the wire impedance.Therefore, there is a concern that false voltage detection due to noise may affect motor control or lead to false detection of overvoltage anomalies. Therefore, attempting to increase the responsiveness of overvoltage detection without considering the difference between wire impedances will increase the risk of malfunction due to noise, such as operation stoppage caused by the protection function, in a case where the difference between the wire impedances from the converter to the inverters is large, on a side where the wire impedance is smaller.Furthermore, an attempt to suppress the occurrence of a malfunction due to noise without considering the difference between the wire impedances will reduce the responsiveness of the overvoltage detection and increase the risk of device malfunction due to a delay in activating the protection function on a side where the wire impedance is larger, that is, where overvoltage protection is important.

[0007] It is necessary to reduce the influence of the difference between the wire impedances caused by the difference between the distances from the converter to the inverters due to limitations of the arrangement within the device.

[0008] The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain a power converter capable of suppressing an influence of a difference in wire impedances between a converter and two inverters and implementing highly reliable operation. Means of solving the problem

[0009] To solve the above-mentioned problems and achieve the object, a power converter according to the present disclosure includes: a converter configured to rectify AC power supplied from an AC power supply; a first inverter and a second inverter, each connected to both ends of a main circuit capacitor configured to smooth a DC power output from the converter; a first voltage detection circuit configured to detect a voltage input to the first inverter and filter a detection value and output the detection value as a first voltage detection value; a second voltage detection circuit configured to detect a voltage input to the second inverter and filter a detection value and output the detection value as a second voltage detection value;a first drive signal generating means configured to perform, based on the first voltage detection value, an operation of generating a drive signal for the first inverter and an operation of protecting the first inverter when an abnormality occurs;and a second drive signal generating means configured to perform, based on the second voltage detection value, an operation of generating a drive signal for the second inverter and an operation of protecting the second inverter when an abnormality occurs. At least one of time constants of the filter circuits and threshold values is set based on the wire impedances between the converter and the first inverter and between the converter and the second inverter. The filter circuits are configured to perform filtering in the first voltage detection circuit and the second voltage detection circuit, and the threshold values are used in abnormality detection processes in the first drive signal generating means and the second drive signal generating means. Effects of the invention

[0010] The power converter according to the present disclosure achieves an effect of suppressing an influence of a difference between the wire impedances between a converter and each of two inverters and implementing highly reliable operation. Short description of the drawings Fig. 1 is a diagram showing an exemplary configuration of a power converter according to a first embodiment. Fig. 2 is a diagram schematically showing the wire impedances of the power converter according to the first embodiment. Fig. 3 is a diagram showing an exemplary configuration of a first voltage detection circuit and a second voltage detection circuit included in the power converter according to the first embodiment. Fig. 4 is a flowchart showing an exemplary operation of a first drive signal generating means included in the power converter according to the first embodiment. Fig. 5 is a diagram showing an exemplary configuration of a power converter according to a second embodiment. Fig. 6 is a diagram showing an exemplary configuration of an air conditioner according to a third embodiment. Description of the embodiments

[0011] Hereinafter, power converters and an air conditioner according to embodiments of the present disclosure will be described in detail with reference to the drawings. First embodiment.

[0012] Fig. 1 is a diagram showing an exemplary configuration of a power converter 100 according to a first embodiment. The power converter 100 includes a converter 2, a reactor 3, a main circuit capacitor 4, a first inverter 5a, a second inverter 5b, a first drive signal generating means 7a, a second drive signal generating means 7b, a first voltage detection circuit 8a, and a second voltage detection circuit 8b.

[0013] The converter 2 is connected to an AC power supply 1 and rectifies and outputs three-phase AC power supplied from the AC power supply 1. The converter 2 can be a passive converter using a diode bridge, or a boost converter capable of increasing the output voltage. The reactor 3 is connected at one end to a positive output end of the converter 2 and at the other end to one end of the main circuit capacitor 4. Another end of the main circuit capacitor 4 is connected to a negative output end of the converter 2. That is, the main circuit capacitor 4 is connected to the other end of the reactor 3 and to the negative output end of the converter 2. Further, the first inverter 5a and the second inverter 5b are connected to both ends of the main circuit capacitor 4.A first motor 6a is connected to the output ends of the first inverter 5a, and a second motor 6b is connected to the output ends of the second inverter 5b.

[0014] The reactor 3 and the main circuit capacitor 4 suppress oscillations of the DC power output from the converter 2 and smooth the DC power output from the converter 2. A voltage across the main circuit capacitor 4 is denoted by V dc0The first inverter 5a converts the DC power input from the converter 2 into AC power via the reactor 3 and the main circuit capacitor 4 and supplies the AC power to the first motor 6a. The first inverter 5a performs a DC-to-AC power conversion operation according to a drive signal input from the first drive signal generating means 7a, which will be described later. The second inverter 5b converts the DC power input from the converter 2 into AC power via the reactor 3 and the main circuit capacitor 4 and supplies the AC power to the second motor 6b. The second inverter 5b performs a DC-to-AC power conversion operation according to a drive signal input from the second drive signal generating means 7b, which will be described later.

[0015] The first drive signal generating means 7a is configured to: generate a drive signal for controlling the operation of the power conversion of the first inverter 5a based on a voltage V dc1 , which is input to the first inverter 5a and detected by the first voltage detection circuit 8a, and an externally input voltage command (not shown); and output the drive signal to the first inverter 5a. The second drive signal generation means 7b is configured to: generate a drive signal for controlling the power conversion operation of the second inverter 5b based on a voltage V dc2, which is input to the second inverter 5b and detected by the second voltage detection circuit 8b, and an externally input voltage command (not shown); and outputs the drive signal to the second inverter 5b. Note that the first drive signal generating means 7a and the second drive signal generating means 7b generate drive signals using a known general drive signal generating method. The first drive signal generating means 7a and the second drive signal generating means 7b are implemented, for example, by a microcontroller. The first drive signal generating means 7a and the second drive signal generating means 7b may be implemented by a single microcontroller or by separate microcontrollers.

[0016] The first voltage detection circuit 8a is configured to: detect a voltage of an input part of the first inverter 5a; and send to the first drive signal generating means 7a a signal corresponding to the detected voltage V dc1 which is input to the first inverter 5a. The second voltage detection circuit 8b is configured to: detect a voltage of an input part of the second inverter 5b; and send a signal corresponding to the detected voltage V to the second drive signal generating means 7b. dc2 which is input to the second inverter 5b.

[0017] Furthermore, the first drive signal generating means 7a and the second drive signal generating means 7b have the function of causing the first inverter 5a and the second inverter 5b, respectively, to stop the power conversion operation when the power converter 100 fails or when a malfunction of the power converter 100 is feared. For example, when the voltage input V detected by the first voltage detection circuit 8a dc1 is greater than a predetermined threshold, the first drive signal generating means 7a determines that an overvoltage abnormality has occurred in which an excessive voltage is applied to the first inverter 5a, and causes the first inverter 5a to stop the power conversion operation. Similarly, when the voltage input V detected by the second voltage detection circuit 8b dc2is greater than a predetermined threshold, the second drive signal generating means 7b determines that an overvoltage abnormality has occurred in which an excessive voltage is applied to the second inverter 5b, and causes the second inverter 5b to stop the power conversion operation.

[0018] There are wire impedances between the converter 2 and the first inverter 5a and between the converter 2 and the second inverter 5b of the power converter 100, as shown in Fig. 2 shown. Fig. 2 is a diagram schematically showing the wire impedances of the power converter 100 according to the first embodiment. In Fig. 2: Z1 denotes an impedance of a wire from the main circuit capacitor 4 to a positive input end of the first inverter 5a; Z2 denotes an impedance of a wire from the main circuit capacitor 4 to a negative input end of the first inverter 5a; Z3 denotes an impedance of a wire from the main circuit capacitor 4 to a positive input end of the second inverter 5b; and Z4 denotes an impedance of a wire from the main circuit capacitor 4 to a negative input end of the second inverter 5b. The wire impedances Z1 to Z4 include minute resistance components and reactance components present on the wires. The wire impedances Z1 to Z4 cause a potential difference between V dc0 and V dc1 , a potential difference between V dc0 and V dc2and a transient voltage fluctuation. It should be noted that the first voltage detection circuit 8a, the second voltage detection circuit 8b, the first drive signal generating means 7a and the second drive signal generating means 7b in Fig. 2 are omitted.

[0019] An increase in the difference between the wire impedance (Z1, Z2) between the converter 2 and the first inverter 5a and the wire impedance (Z3, Z4) between the converter 2 and the second inverter 5b may result in a difference between the response time required to start the protective operation for the first inverter 5a to stop the power conversion operation and the response time required to start the protective operation for the second inverter 5b to stop the power conversion operation when an overvoltage occurs. This increases the probability of an element being damaged due to a delay in protecting one of the inverters. In addition, a difference between voltage fluctuations due to the influence of noise increases. This increases the probability of an overvoltage anomaly being falsely detected and leading to an unnecessary operation stop.

[0020] To suppress the influence of such a difference between the wire impedances, the first voltage detection circuit 8a and the second voltage detection circuit 8b include filter circuits, and the time constants (hereinafter referred to as filter time constants) of the filter circuits are separately set in the power converter 100 according to the present embodiment. That is, setting the filter time constants of the filter circuits to different values reduces the influence of the difference between the wire impedance between the converter 2 and the first inverter 5a and the wire impedance between the converter 2 and the second inverter 5b.

[0021] Fig. 3 is a diagram showing an exemplary configuration of the first voltage detection circuit 8a and the second voltage detection circuit 8b included in the power converter 100 according to the first embodiment.

[0022] The first voltage detection circuit 8a and the second voltage detection circuit 8b each include a resistance voltage dividing circuit 81 and an RC circuit 82. The resistance voltage dividing circuit 81 is used to detect a voltage input to an inverter (the first inverter 5a, the second inverter 5b). The RC circuit 82 is a filter circuit. The RC circuit 82 is connected in parallel to a resistor having a resistance value of R2, which is one of two resistors included in the resistance voltage dividing circuit 81. A filter time constant of the RC circuit 82 included in the first voltage detection circuit 8a and a filter time constant of the RC circuit 82 included in the second voltage detection circuit 8b are calculated based on the wire impedances Z1, Z2, Z3, and Z4 shown in Fig. 2 are set so as to reduce a difference between the response time required for the first drive signal generating means 7a to detect an abnormality and the response time required for the second drive signal generating means 7b to detect an abnormality in the event of the abnormalities. A time constant T[sec] of the RC circuit 82 is determined by the product of a resistance value R[Ω] of a resistor included in a circuit and a value C[F] of the capacitance of a capacitor included in the circuit. Therefore, the respective time constants T of the first voltage detection circuit 8a and the second voltage detection circuit 8b are set to different values to suppress the influence of the difference between the wire impedances.Specifically, the time constant T is set to a larger value on a side with a smaller wire impedance than on a side with a larger wire impedance. This prevents a decrease in the responsiveness of detecting an overvoltage anomaly on the side with the larger wire impedance. It also prevents an overvoltage anomaly from being easily detected when a voltage fluctuation due to noise occurs on the side with the smaller wire impedance, thus preventing malfunction.

[0023] It should be noted that the Fig. 3 can be replaced by a known voltage sensor such that the first voltage detection circuit 8a and the second voltage detection circuit 8b are each configured as a combination of the voltage sensor and the RC circuit 82.

[0024] Each of the first drive signal generating means 7a and the second drive signal generating means 7b may further have the function of generating, based on both the voltage V applied to the first inverter 5a dc1 as well as the voltage applied to the second inverter 5b to determine whether an error has occurred.

[0025] A description will be given of the operation in which the first drive signal generating means 7a and the second drive signal generating means 7b detect an error based on both the voltage V dc1 , which is input to the first inverter 5a, as well as the voltage V dc2input to the second inverter 5b, and cause the first inverter 5a and the second inverter 5b, respectively, to stop the power conversion operation. Since the first drive signal generating means 7a and the second drive signal generating means 7b operate similarly, the operation of the first drive signal generating means 7a will be described here.

[0026] Fig. 4 is a flowchart showing the exemplary operation of the first drive signal generating means 7a included in the power converter 100 according to the first embodiment. In particular, Fig. 4 shows the exemplary operation of detecting a fault of the power converter 100 and causing the first inverter 5a to stop the power conversion operation.

[0027] The first drive signal generating means 7a begins generating a drive signal for the first inverter 5a (step S11) and outputs the generated drive signal to the first inverter 5a. After starting to generate the drive signal, the first drive signal generating means 7a first detects a first voltage detection value V dc1 from the first voltage detection circuit 8a (step 12). Further, the first drive signal generating means 7a outputs the first voltage detection value V dc1 detected in step S12 to the second drive signal generating means 7b (step S13). It should be noted that the first voltage detection value V dc1 detected in step S12 is also used in generating a drive signal for the first inverter 5a.

[0028] Next, the first drive signal generating means 7a detects a second voltage detection value V from the second drive signal generating means 7b. dc2 detected by the second voltage detection circuit 8b (step S14). Note that the processing in step S13 and the processing in step S14 may be performed in reverse order.

[0029] Next, the first drive signal generating means 7a checks whether an absolute value of a difference between the first voltage detection value V dc1 and the second voltage detection value is greater than a predetermined threshold value V lim is, ie, whether “V lim <|V dc1 -V dc1 |“ applies (step S15). The threshold value V limis a threshold value for determining the occurrence of a fault of the power converter 100. When both the first inverter 5a and the second inverter 5b are in normal operation, there is no large difference between the first voltage detection value V dc1 and the second voltage detection value V dc2 However, if one of the first inverter 5a and the second inverter 5b fails, a sudden change in the voltage input to the inverter where an abnormality has occurred occurs. This results in a large difference between the first voltage detection value V dc1 and the second voltage detection value V dc2 -Therefore, the first drive signal generating means 7a determines in step S15 whether an error has occurred by calculating the absolute value of the difference between the first voltage detection value V dc1 and the second voltage detection value V dc2 with the threshold value Vlim compares.

[0030] If the absolute value of the difference between the first voltage detection value V dc1 and the second voltage detection value V dc2 equal to the threshold value V lim (Step S15: No) or less, the first drive signal generating means 7a returns to step S12 and repeats the processing of steps S12 to S15. Furthermore, the first drive signal generating means 7a continues the operation of generating a drive signal for the first inverter 5a.

[0031] In addition, if the absolute value of the difference between the first voltage detection value V dc1 and the second voltage detection value V dc2 greater than the threshold V limis (step S15: Yes), the first drive signal generating means 7a stops generating a drive signal for the first inverter 5a (step S16) and causes the first inverter 5a to stop the power conversion operation. At this time, the first drive signal generating means 7a performs control so that all switching elements included in the first inverter 5a are in an off state.

[0032] It should be noted that in step S14 of the Fig. 4, the first drive signal generating means 7a acquires the second voltage detection value from the second drive signal generating means 7b, however, the first drive signal generating means 7a may be configured such that the first drive signal generating means 7a acquires the second voltage detection value directly from the second voltage detection circuit 8b.

[0033] Furthermore, a fault could be detected only by the first drive signal generating means 7a or the second drive signal generating means 7b, although the second drive signal generating means 7b operates like the first drive signal generating means 7a to detect a fault and cause the second inverter 5b to stop the power conversion operation as described above. For example, if only the first drive signal generating means 7a detects a fault, the Fig. 4 is omitted, and if an error is detected in step S15, ie, if it is determined that the absolute value of the difference between the first voltage detection value V dc1 and the second voltage detection value is greater than the threshold value V limis, the first drive signal generating means 7a notifies the second drive signal generating means 7b of the detection of the fault and executes step S16. When the second drive signal generating means 7b receives the notification from the first drive signal generating means 7a that the fault has been detected, it stops generating a drive signal for the second inverter 5b and causes the second inverter 5b to stop the power conversion operation.

[0034] As described above, the power converter 100 according to the present embodiment includes: the converter 2 that rectifies AC power; the first inverter 5a; the second inverter 5b that converts DC power from the converter 2 into AC power for driving connected loads; the first voltage detection circuit 8a that detects the first voltage detection value V dc1which is a voltage value of the input part of the first inverter 5a; the first drive signal generating means 7a, which generates a drive signal for the first inverter 5a based on the first voltage detection value V dc1 and causes the first inverter 5a to stop operation when a voltage abnormality is detected; the second voltage detection circuit 8b, which generates the second voltage detection value V dc2 which is a voltage value of the input part of the second inverter 5b; and the second drive signal generating means 7b which generates a drive signal for the second inverter 5b based on the second voltage detection value V dc2 and causes the second inverter 5b to stop operation when a voltage abnormality is detected. When the first voltage detection value V dc1is greater than a predetermined threshold, the first voltage detection circuit 8a determines that the voltage is abnormal, and when the second voltage detection value is greater than a predetermined threshold, the second voltage detection circuit 8b determines that the voltage is abnormal. In addition, the first voltage detection circuit 8a and the second voltage detection circuit 8b include filter circuits that filter voltage detection values, and the time constants of the filter circuits are different. The time constant of the filter circuit included in the first voltage detection circuit 8a and the time constant of the filter circuit included in the second voltage detection circuit 8b are determined based on the wire impedances between the converter 2 and the first inverter 5a and the wire impedances between the converter 2 and the second inverter 5b, respectively.

[0035] The power converter 100 according to the present embodiment can achieve highly reliable operation by setting the respective time constants of the filter circuits of the first voltage detection circuit 8a and the second voltage detection circuit 8b to different values to suppress the influence of the difference between the wire impedances between the converter 2 and the first inverter 5a and between the converter 2 and the second inverter 5b.

[0036] It should be noted that the Fig. 1 assumes that the AC power supply 1 connected to the power converter 100 is a three-phase AC power supply, but the AC power supply 1 may be a single-phase AC power supply. Furthermore, although the configuration in which the reactor 3 (DC reactor) is provided on a DC bus bar connecting the converter 2 and the main circuit capacitor 4 was described above, an AC reactor may be provided on a power supply cable connecting the AC power supply 1 and the converter 2. In addition, although an example in which the main circuit capacitor 4 is an electrolytic capacitor was described, a film capacitor may also be used as the main circuit capacitor 4. Second embodiment.

[0037] Fig. 5 is a diagram showing an exemplary configuration of a power converter 100a according to a second embodiment. Like the power converter 100 according to the first embodiment, the power converter 100a includes the converter 2, the reactor 3, the main circuit capacitor 4, the first inverter 5a, the second inverter 5b, the first drive signal generating means 7a, the second drive signal generating means 7b, the first voltage detection circuit 8a, and the second voltage detection circuit 8b, and converts the three-phase AC power output from the AC power supply 1 to generate three-phase AC power for driving both the first motor 6a and the second motor 6b.

[0038] The power converter 100a according to the second embodiment differs from the power converter 100 according to the first embodiment in that a first power conversion circuit including the first inverter 5a, the first drive signal generating means 7a, and the first voltage detection circuit 8a is mounted on a first substrate 10a, and a second power conversion circuit including the second inverter 5b, the second drive signal generating means 7b, and the second voltage detection circuit 8b is mounted on a second substrate 10b provided separately from the first substrate 10a.

[0039] As described above, the two power conversion circuits, including the inverters and their peripheral circuits, are mounted on different substrates. This allows the same effect as the power converter 100 according to the first embodiment to be achieved. Furthermore, since the signals on the power conversion circuits do not interfere with each other, malfunction of the power conversion circuits mounted on each substrate can be prevented, further improving operational reliability. Third embodiment.

[0040] In the present embodiment, a device to which each of the power converters described in the first and second embodiments is applied will be described. As an example, an air conditioner implemented by applying the power converter 100 described in the first embodiment will be described.

[0041] Fig. 6 is a diagram showing an exemplary configuration of an air conditioner 200 according to a third embodiment. The air conditioner 200 according to the third embodiment includes the power converter 100 described in the first embodiment. The power converter 100 is connected to the AC power supply 1. Note that the power converter 100 can be replaced with the power converter 100a described in the second embodiment.

[0042] In addition, the air conditioner 200 includes: a compressor motor 6c and a compression element 61 constituting the compression element 61; a blower motor 6d that rotates a blower 62; a four-way valve 121 constituting a refrigeration cycle 110 with the compression element 61; a heat source-side heat exchanger 122; an expansion means 131; and a load-side heat exchanger 132. The power converter 100, the compressor 60, the blower motor 6d, the blower 62, the four-way valve 121, and the heat source-side heat exchanger 122 are provided in an outdoor unit 120 of the air conditioner 200. The expansion means 131 and the load-side heat exchanger 132 are provided in an indoor unit 130 of the air conditioner 200. For example, the compressor motor 6c corresponds to the first motor 6a provided in Fig. 1, and the blower motor 6d corresponds to the second motor 6b shown in Fig. 1. It should be noted that the configuration of the refrigeration cycle 110 is not limited to that shown in Fig. 6 shown configuration is limited. Fig. 6 shows a known exemplary configuration.

[0043] In the power converter 100 to be applied to the air conditioner 200, a time constant of a filter included in a voltage detection circuit that detects a voltage input to an inverter to which the blower motor 6d is connected is set to a value greater than a time constant of a filter included in a voltage detection circuit that detects a voltage input to an inverter to which the compressor motor 6c is connected. Furthermore, the first drive signal generating means 7a and the second drive signal generating means 7b detect overvoltage abnormalities using the same threshold value.

[0044] With such a configuration, in a case where the amounts of transient change of the voltage inputs to the inverters are equal at the time of an abnormality in the power converter 100 or 100a, the operation of the first inverter 5a on a side with a smaller filter time constant, where the compressor 60 is arranged, is stopped first in the air conditioner 200. Therefore, the second inverter 5b driving the fan motor 6d continues its operation, and the fan motor 6d continues its rotation even if the first inverter 5a driving the compressor motor 6c stops its operation due to the execution of the overvoltage abnormality protection operation. Thus, the cooling of the power converter 100 or 100a by the wind generated by the fan 62 can continue even if the compressor 60 is stopped.Accordingly, electronic components such as the switching elements included in the first inverter 5a can be protected.

[0045] Furthermore, the air conditioner 200 according to the present embodiment can reduce the risk that the air conditioner 200 abnormally stops the air conditioning operation due to a malfunction of the power converter 100 or 100a when performing the protective operation. Thus, user comfort can be improved. Fourth embodiment.

[0046] In the power converters 100 and 100a of the air conditioner 200 according to the third embodiment, the time constants of the filter circuits included in the first voltage detection circuit 8a and the second voltage detection circuit 8b are set to different values to attenuate the influence of the difference in the wire impedances between the converter 2 and the first inverter 5a and between the converter 2 and the second inverter 5b. Meanwhile, another method may be used to attenuate the influence.

[0047] For example, the first drive signal generating means 7a and the second drive signal generating means 7b may use different threshold values for determining overvoltage anomalies to mitigate the influence of the difference between the wire impedances. In this case, the time constant of the filter circuit included in the first voltage detection circuit 8a and the time constant of the filter circuit included in the second voltage detection circuit 8b may be set to the same value or to different values.That is, at least either the time constants of the filter circuits included in the voltage detection circuits or the threshold values to be used by the drive signal generating means for determining overvoltage anomalies can be set to different values in order to dampen the influence of the difference between the wire impedances between the converter 2 and the first inverter 5a and between the converter 2 and the second inverter 5b.

[0048] In a case where the threshold values used by the first drive signal generating means 7a and the second drive signal generating means 7b for determining an overvoltage abnormality are set to different values in order to attenuate the influence of the difference between the wire impedances between the converter 2 and the first inverter 5a and between the converter 2 and the second inverter 5b, a threshold value used for determining overvoltage abnormalities in a drive signal generating means that generates a drive signal for the inverter connected to the blower motor 6d is set to a value larger than a threshold value used for determining overvoltage abnormalities in a drive signal generating means that generates a drive signal for the inverter connected to the compressor motor 6c.

[0049] The threshold values used by the drive signal generating means (the first drive signal generating means 7a and the second drive signal generating means 7b) to determine overvoltage anomalies are determined based on the wire impedances between the converter 2 and the first inverter 5a and between the converter 2 and the second inverter 5b, respectively.

[0050] Given that the power converters 100 and 100a described in the first and second embodiments are respectively used in an air conditioner, in the present embodiment, at least one of the time constant of the filter circuit included in each voltage detection circuit and the threshold value used by each drive signal generation means for determining overvoltage abnormalities is adjusted to reduce an influence on the operating characteristics caused by the impedance of the wire from the converter 2 to the input part of each inverter. However, the configuration of the present embodiment is not limited to this.Likewise, when using the power converters 100 and 100a in other devices (devices other than air conditioners), it is possible to reduce the influence of the wire impedance on the operating characteristics by adjusting at least either the time constant of the filter circuit included in each voltage detection circuit or the threshold value to be used by each drive signal generating means for determining overvoltage anomalies.

[0051] The configurations explained in the above embodiments show examples, and it is possible to combine the configurations with another known technique or to combine the embodiments with each other, and it is also possible to partially omit or change the configurations without departing from the scope of the present disclosure. List of reference symbols 1 AC power supply; 2 converters; 3 throttle; 4 main circuit capacitor; 5a first inverter; 5b second inverter; 6a first engine; 6b second engine; 6c compressor motor; 6d blower motor; 7a first drive signal generating means; 7b second drive signal generating means; 8a first voltage detection circuit; 8b second voltage detection circuit; 10a first substrate; 10b second substrate; 60 compressor; 61 compression element; 62 fans; 81 resistance voltage division circuit; 82 RC circuit; 100, 100a power converter; 110 Refrigeration circuit; 120 outdoor unit; 121 four-way valve; 122 heat source side heat exchanger; 130 indoor unit; 131 expansion agents; 132 load-side heat exchanger; 200 air conditioning. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] JP 2020-61913

[0004]

Claims

[1] Power converter, comprising: a converter configured to rectify AC power supplied from an AC power supply; a first inverter and a second inverter each connected to both ends of a main circuit capacitor configured to smooth DC power output from the converter; a first voltage detection circuit configured to detect a voltage input to the first inverter; and filter a detection value and output the detection value as a first voltage detection value; a second voltage detection circuit configured to detect a voltage input to the second inverter, filter a detection value, and output the detection value as a second voltage detection value; a first drive signal generating means configured to perform, based on the first voltage detection value, an operation of generating a drive signal for the first inverter and an operation of protecting the first inverter when an abnormality occurs; and a second drive signal generating means configured to perform, based on the second voltage detection value, an operation of generating a drive signal for the second inverter and an operation of protecting the second inverter when an abnormality occurs, wherein at least one of time constants of filter circuits or threshold values is set based on wire impedances between the converter and the first inverter and between the converter and the second inverter, wherein the filter circuits are configured to perform the filtering in the first voltage detection circuit and the second voltage detection circuit, and wherein the threshold values are used in anomaly detection processes in the first drive signal generating means and the second drive signal generating means. [2] The power converter according to claim 1, wherein the first drive signal generating means and the second drive signal generating means further have functions of detecting abnormalities in the first inverter and the second inverter, respectively, based on a difference between the first voltage detection value and the second voltage detection value, and causing the first inverter and the second inverter, respectively, to stop an operation when abnormalities are detected based on the difference. [3] Power converter according to claim 1 or 2, wherein the first voltage detection circuit, the first drive signal generating means, and the first inverter are mounted on a first substrate; and wherein the second voltage detection circuit, the second drive signal generating means and the second inverter are mounted on a second substrate provided separately from the first substrate. [4] Power converter according to one of claims 1 to 3, wherein, in a case where the time constants of the filter circuits included in the first voltage detection circuit and the second voltage detection circuit are set based on the wire impedances, the time constants are set such that a time constant of a filter circuit included in the first voltage detection circuit is smaller than a time constant of a filter circuit included in the second voltage detection circuit when a wire impedance between the converter and the first inverter is larger than a wire impedance between the converter and the second inverter; and wherein the time constants are set such that the time constant of the filter circuit included in the first voltage detection circuit is greater than the time constant of the filter circuit included in the second voltage detection circuit when the wire impedance between the converter and the first inverter is smaller than the wire impedance between the converter and the second inverter. [5] Power converter according to one of claims 1 to 4, wherein in a case where the threshold values to be used in the abnormality detection processes in the first drive signal generating means and the second drive signal generating means are set based on the wire impedances: the threshold values are set such that a threshold value to be used in an abnormality detection process in the first drive signal generating means is smaller than a threshold value to be used in an abnormality detection process in the second drive signal generating means when a wire impedance between the converter and the first inverter is larger than a wire impedance between the converter and the second inverter; and the threshold values are set such that the threshold value to be used in the anomaly detection process in the first drive signal generating means is larger than the threshold value to be used in the anomaly detection process in the second drive signal generating means when the wire impedance between the converter and the first inverter is smaller than the wire impedance between the converter and the second inverter. [6] Air conditioning system, comprising: the power converter according to one of claims 1 to 3, wherein the first inverter is adapted to drive a compressor motor provided in a compressor, wherein the second inverter is adapted to drive a fan motor to rotate a fan, and wherein the time constants are set such that a time constant of a filter circuit included in the second voltage detection circuit is greater than a time constant of a filter circuit included in the first voltage detection circuit. [7] Air conditioning system, comprising: the power converter according to one of claims 1 to 3, wherein the first inverter is adapted to drive a compressor motor provided in a compressor, and wherein the second inverter is adapted to drive a fan motor to rotate a fan, and wherein the threshold values are set such that a threshold value to be used in an abnormality detection process in the second drive signal generating means is larger than a threshold value to be used in an abnormality detection process in the first drive signal generating means.

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