State detection circuit, control device, state detection method, control method, and program

Abstract

Provided are a control device, a state detection circuit, a state detection method, a control method, and a program that enable early detection of the state of a refrigeration cycle device. The control device (1) comprises: a state detection circuit (3); and a control circuit (6) that controls a drive circuit (2) that drives a motor (11) of a compressor of the refrigeration cycle device. The state detection circuit (3) outputs at least one of the frequency and signal strength of a target high-frequency component from the target high-frequency component that is higher than a carrier frequency of an inverter circuit (22) separated from an electric signal passing through connection lines (Lu, Lv, Lw) between the inverter circuit (22) and motor (11) of the drive circuit (2), and the control circuit (6) stops or restricts the operation of the drive circuit (2) when, on the basis of at least one of the output frequency and signal strength, it is determined that the state of the refrigeration cycle device is in a non-steady state.

Description

State detection circuit, control device, state detection method, control method, and program

[0001] The present disclosure relates to a state detection circuit, a control device, a state detection method, a control method, and a program.

[0002] Patent Literature 1 discloses a diagnostic device for a power conversion device that drives a motor. The diagnostic device includes a data acquisition unit that acquires target data related to current values ​​between the power conversion device and the motor, a detection unit that detects peak values ​​in a time-series waveform of the target data, a counting unit that calculates the amplitude and occurrence frequency of the peak values ​​using a frequency counting method, and a diagnostic unit that diagnoses an abnormality in the motor based on the amplitude and occurrence frequency. The diagnostic unit diagnoses an abnormality in the motor if statistics calculated from the amplitude and occurrence frequency do not satisfy a predetermined criterion.

[0003] Patent No. 7151827

[0004] In Patent Document 1, statistics calculated from amplitude and frequency of occurrence are used to diagnose motor abnormalities. Since it takes a relatively long time to obtain such statistics, it is difficult to detect abnormalities such as layer shorts in the motor at an early stage.

[0005] The present disclosure provides a control device, a state detection circuit, a state detection method, a control method, and a program that enable early detection of a state.

[0006] A control device according to one aspect of the present disclosure is a control device for controlling a refrigeration cycle device, and includes a state detection circuit and a control circuit for controlling a drive circuit that drives a motor of a compressor of the refrigeration cycle device. The state detection circuit includes a high-frequency separator that separates target high-frequency components higher than the carrier frequency of the inverter circuit from an electrical signal passing through a connecting line between the inverter circuit of the drive circuit and the motor, and an analyzer that outputs at least one of the frequency and signal strength of the target high-frequency components from the target high-frequency components separated by the high-frequency separator. The control circuit stops or restricts operation of the drive circuit when it determines that the state of the refrigeration cycle device is in an unsteady state based on at least one of the frequency and signal strength output from the analyzer.

[0007] A state detection circuit according to one aspect of the present disclosure is a state detection circuit for detecting the state of a refrigeration cycle device, and includes: a high-frequency separator that separates target high-frequency components higher than the carrier frequency of the inverter circuit from an electrical signal passing through a connecting line between the inverter circuit of a drive circuit that drives the motor of a compressor of the refrigeration cycle device and the motor; an analyzer that outputs at least one of the frequency and signal strength of the target high-frequency components from the target high-frequency components separated by the high-frequency separator; and a processing circuit that determines the state of the refrigeration cycle device based on at least one of the frequency and signal strength output from the analyzer.

[0008] A state detection method according to one aspect of the present disclosure acquires a target high-frequency component higher than the carrier frequency of the inverter circuit separated from an electrical signal passing through a connecting line between the inverter circuit of a drive circuit that drives the motor of a compressor of a refrigeration cycle device and the motor, outputs at least one of the frequency and signal strength of the target high-frequency component based on the target high-frequency component, and determines the state of the refrigeration cycle device based on at least one of the frequency and signal strength.

[0009] A control method according to one aspect of the present disclosure acquires a target high-frequency component higher than the carrier frequency of an inverter circuit separated from an electrical signal passing through a connecting line between the inverter circuit of a drive circuit that drives a compressor motor of a refrigeration cycle device and the motor, outputs at least one of the frequency and signal strength of the target high-frequency component from the target high-frequency component, and stops or restricts operation of the drive circuit when it is determined that the state of the refrigeration cycle device is in an unsteady state based on at least one of the frequency and signal strength.

[0010] A program according to one aspect of the present disclosure is a program for causing a computer system to execute the above-described state detection method.

[0011] A program according to one aspect of the present disclosure is a program for causing a computer system to execute the above control method.

[0012] Aspects of the present disclosure allow for earlier detection of the condition.

[0013] Schematic circuit diagram of a control device including a state detection circuit according to one embodiment. Schematic circuit diagram of a state detection circuit according to one embodiment. Part of a flowchart of the operation of the control device ... Schematic circuit diagram of a state detection circuit according to one modified example. Schematic circuit diagram of a state detection circuit according to one modified example. Schematic circuit diagram of a state detection circuit according to one modified example. Schematic circuit diagram of a control device according to one modified example.

[0014] [1. Embodiments] Hereinafter, embodiments of the present disclosure will be described, with reference to the drawings where appropriate. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following content (e.g., the shape, dimensions, and arrangement of each component). Positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings unless otherwise specified. Each figure described in the following embodiments is a schematic diagram, and the ratios of the size and thickness of each component in each figure do not necessarily reflect the actual dimensional ratios. Furthermore, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0015] In the following description, when it is necessary to distinguish between multiple components, prefixes such as "first" and "second" are added to the names of the components. However, when the components can be distinguished from each other by the symbols attached to them, the prefixes such as "first" and "second" may be omitted in consideration of readability of the text.

[0016] 1 is a schematic circuit diagram of a control device 1 according to this embodiment. The control device 1 controls a motor (electric motor) 11.

[0017] The motor 11 is, for example, a brushless motor (three-phase brushless motor). The motor 11 includes, for example, a rotor and a stator disposed around the rotor. The stator is configured, for example, by concentrating or dispersing a stator winding (magnet wire, etc.) around a stator core (electromagnetic steel sheet, etc.) with an insulating material such as insulating paper interposed therebetween. The stator winding is covered with an insulating material. Examples of insulating materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid polymer, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), etc.

[0018] The control device 1 includes a drive circuit 2 , a state detection circuit 3 , a first protection device 4 , a second protection device 5 , and a control circuit 6 .

[0019] The drive circuit 2 drives the motor 11 based on input power from a power supply 10. In this embodiment, the power supply 10 is an AC power supply, and the input power is AC power. The drive circuit 2 includes a converter circuit 21 and an inverter circuit 22.

[0020] The converter circuit 21 outputs DC output power based on the input power from the power supply 10 so that the voltage becomes a first voltage. That is, the converter circuit 21 converts the input power into DC output power so that the voltage of the DC output power becomes the first voltage. The first voltage corresponds to the rated voltage of the drive circuit 2.

[0021] The converter circuit 21 includes a rectifier circuit 21a and a smoothing circuit 21b.

[0022] The rectifier circuit 21a is a diode bridge composed of a plurality of diodes D1 to D4. The power supply 10 is connected between the input terminals of the rectifier circuit 21a (the connection point between the diodes D1 and D2 and the connection point between the diodes D3 and D4), and the smoothing circuit 21b is connected between the output terminals of the rectifier circuit 21a (the connection point between the diodes D1 and D3 and the connection point between the diodes D2 and D4).

[0023] The smoothing circuit 21b smoothes and outputs the voltage between the output terminals of the rectifier circuit 21a. The smoothing circuit 21b sets the voltage of the DC output power to a first voltage. The smoothing circuit 21b includes a series circuit of an inductor L1 and smoothing capacitors C1 and C2. In the smoothing circuit 21b, the connection point between the inductor L1 and the smoothing capacitor C1 is a first output point P1 that outputs a voltage corresponding to the first voltage. In the smoothing circuit 21b, the connection point between the diodes D2 and D4 and the smoothing capacitor C2 is a second output point P2 that outputs a voltage lower than the voltage at the first output point P1. In the smoothing circuit 21b, the connection point between the smoothing capacitor C1 and the smoothing capacitor C2 is a third output point P3 that outputs a voltage between the voltage at the first output point P1 and the voltage at the second output point P2. In the relationship between the first output point P1, the second output point P2, and the third output point P3, the first output point P1 is a high-voltage point, the second output point P2 is a low-voltage point, and the third output point P3 is an intermediate-voltage point. In the smoothing circuit 21b, the smoothing capacitors C1 and C2 have the same capacitance. Therefore, the voltage between the first output point P1 and the third output point P3 is equal to the voltage between the second output point P2 and the third output point P3. If the voltage between the first output point P1 and the second output point P2 (which corresponds to the first voltage) is E, the voltage between the first output point P1 and the third output point P3 is E / 2, and similarly, the voltage between the second output point P2 and the third output point P3 is E / 2. This allows the drive circuit 2 to provide five voltage levels: E, E / 2, 0, −E / 2, and −E.

[0024] The inverter circuit 22 outputs AC output power to the motor 11 based on the DC output power from the converter circuit 21. In this embodiment, the AC output power is three-phase AC power. The inverter circuit 22 includes a plurality of semiconductor switching elements U1 to U4, V1 to V4, and W1 to W4. The semiconductor switching elements U1 to U4, V1 to V4, and W1 to W4 are, for example, transistors.

[0025] The semiconductor switching elements U1 to U4, V1 to V4, and W1 to W4 each form a series circuit and are connected between a first output point P1 and a second output point P2.

[0026] The connection point of the semiconductor switching elements U1 and U2, the connection point of the semiconductor switching elements V1 and V2, and the connection point of the semiconductor switching elements W1 and W2 are connected to a third output point P3 via diodes D5, D7, and D9, respectively.

[0027] The anodes of diodes D5, D7, and D9 are connected to the third output point P3, and the cathodes of diodes D5, D7, and D9 are connected to the connection point of semiconductor switching elements U1 and U2, the connection point of semiconductor switching elements V1 and V2, and the connection point of semiconductor switching elements W1 and W2, respectively.

[0028] The connection point of the semiconductor switching elements U2 and U3 forms a U-phase output terminal Pu connected to a U-phase input terminal of the motor 11. The connection point of the semiconductor switching elements V2 and V3 forms a V-phase output terminal Pv connected to a V-phase input terminal of the motor 11. The connection point of the semiconductor switching elements W2 and W3 forms a W-phase output terminal Pw connected to a W-phase input terminal of the motor 11.

[0029] The connection point of the semiconductor switching elements U3 and U4, the connection point of the semiconductor switching elements V3 and V4, and the connection point of the semiconductor switching elements W3 and W4 are connected to a third output point P3 via diodes D6, D8, and D10, respectively.

[0030] The cathodes of diodes D6, D8, and D10 are connected to the third output point P3, and the anodes of diodes D6, D8, and D10 are connected to the connection point of semiconductor switching elements U3 and U4, the connection point of semiconductor switching elements V3 and V4, and the connection point of semiconductor switching elements W3 and W4, respectively.

[0031] In the inverter circuit 22, the semiconductor switching elements U1, U2, V1, V2, W1, and W2 constitute a first semiconductor switching element group connected between the first output point P1 and the motor 11. In particular, the semiconductor switching elements U1 and U2 constitute a U-phase first semiconductor switching element group connected between the first output point P1 and a U-phase input terminal of the motor 11. The semiconductor switching elements V1 and V2 constitute a V-phase first semiconductor switching element group connected between the first output point P1 and a V-phase input terminal of the motor 11. The semiconductor switching elements W1 and W2 constitute a W-phase first semiconductor switching element group connected between the first output point P1 and a W-phase input terminal of the motor 11.

[0032] The semiconductor switching elements U3, U4, V3, V4, W3, and W4 constitute a second semiconductor switching element group connected between the second output point P2 and the motor 11. In particular, the semiconductor switching elements U3 and U4 constitute a U-phase second semiconductor switching element group connected between the second output point P2 and the U-phase input terminal of the motor 11. The semiconductor switching elements V3 and V4 constitute a V-phase second semiconductor switching element group connected between the second output point P2 and the V-phase input terminal of the motor 11. The semiconductor switching elements W3 and W4 constitute a W-phase second semiconductor switching element group connected between the second output point P2 and the W-phase input terminal of the motor 11.

[0033] The semiconductor switching elements U2, U3, V2, V3, W2, and W3 constitute a third semiconductor switching element group connected between the third output point P3 and the motor 11. In particular, the semiconductor switching elements U2 and U3 constitute a U-phase third semiconductor switching element group connected between the third output point P3 and the U-phase input terminal of the motor 11. The semiconductor switching elements V2 and V3 constitute a V-phase third semiconductor switching element group connected between the third output point P3 and the V-phase input terminal of the motor 11. The semiconductor switching elements W2 and W3 constitute a W-phase third semiconductor switching element group connected between the third output point P3 and the W-phase input terminal of the motor 11.

[0034] The converter circuit 21 has a plurality of output points including first to third output points P1 to P3. The inverter circuit 22 has a plurality of semiconductor switching element groups including a first semiconductor switching element group (semiconductor switching elements U1, U2, V1, V2, W1, W2) connected between the first output point P1 and the motor 11, a second semiconductor switching element group (semiconductor switching elements U3, U4, V3, V4, W3, W4) connected between the second output point P2 and the motor 11, and a third semiconductor switching element group (semiconductor switching elements U2, U3, V2, V3, W2, W3) connected between the third output point P3 and the motor 11. The drive circuit 2 is a so-called multilevel inverter, particularly a three-level inverter.

[0035] The inverter circuit 22 is connected to the motor 11 by connection lines Lu, Lv, and Lw. The connection lines Lu, Lv, and Lw are connection lines for the U, V, and W phases, respectively. The connection lines Lu, Lv, and Lw connect the U-phase, V-phase, and W-phase output terminals Pu, Pv, and Pw of the inverter circuit 22 to the U-phase, V-phase, and W-phase input terminals of the motor 11, respectively.

[0036] The state detection circuit 3 is provided for detecting the state. The state detection circuit 3 includes a high-frequency separator 31, an analyzer 32, and a processing circuit. In this embodiment, the control circuit 6 functions as the processing circuit. The state detection circuit 3 will be further described with reference to FIG. 2. FIG. 2 is a schematic circuit diagram of the state detection circuit 3. The processing circuit (control circuit 6) is not shown in FIG. 2.

[0037] The high-frequency separator 31 separates target high-frequency components higher than the carrier frequency of the inverter circuit 22 from the electrical signals passing through the connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 that drives the motor 11 and the motor 11. The higher the carrier frequency, the smoother the waveform of the AC output power output from the inverter circuit 22. However, a higher carrier frequency increases the number of switching losses, which can be a factor in increasing circuit loss. The carrier frequency is, for example, 2 kHz or higher and 10 kHz or lower.

[0038] The high-frequency separator 31 includes high-pass filters 311a, 311b, and 311c. The high-pass filters 311a, 311b, and 311c are connected between the connecting lines Lu, Lv, and Lw and the analyzer 32, respectively. The high-pass filters 311a, 311b, and 311c pass high-frequency components higher than the carrier frequency of the inverter circuit 22. The high-pass filters 311a, 311b, and 311c are LC type. The high-pass filters 311a, 311b, and 311c include inductors L31, L32, and L33 inserted in the connecting lines Lu, Lv, and Lw, respectively, and capacitors C31, C32, and C33 connected between the ends of the inductors L31, L32, and L33 on the motor 11 side and the analyzer 32, respectively. The capacitances of the capacitors C31, C32, and C33 and the inductances of the inductors L31, L32, and L33 are set so as to pass high frequency components higher than the carrier frequency of the inverter circuit 22.

[0039] The analyzer 32 outputs at least one of the frequency and signal strength of the target high-frequency component from the target high-frequency component separated by the high-frequency separator 31. The analyzer 32 can be realized, for example, by a computer system including at least one processor (microprocessor) and one or more memories. The analyzer 32 executes a calculation process to determine at least one of the frequency and signal strength of the target high-frequency component from the target high-frequency component separated by the high-frequency separator. In this embodiment, the analyzer 32 performs a fast Fourier transform on the target high-frequency component separated by the high-frequency separator 31 to determine the frequency and signal strength of the target high-frequency component. At least one of the frequency and signal strength of the target high-frequency component determined by the analyzer 32 is output to the control circuit 6, which functions as a processing circuit.

[0040] In this embodiment, the state detected by the state detection circuit 3 is determined to be an unsteady state. When the control device 1 controls the compressor of the refrigeration cycle device, the unsteady state includes, for example, an abnormality in at least one of the compressor of the refrigeration cycle device and the drive circuit 2, a state in which a discharge phenomenon that may cause a disproportionation reaction of the working medium of the refrigeration cycle device has occurred or may occur, or a state in which a disproportionation reaction of the working medium of the refrigeration cycle device is progressing or may progress. In this embodiment, the unsteady state is an abnormality in the motor 11. The abnormality in the motor 11 is a layer short. The inventors have found that when a layer short occurs in the motor 11, the frequency of ringing changes in the voltage between the connection lines Lu, Lv, and Lw. The cause of this change in ringing frequency is thought to be an impedance mismatch between the drive circuit 2 and the motor 11. This impedance mismatch is thought to be caused by a change in the impedance of the motor 11 due to a change in the inductance of the motor 11 (the inductance of the coil of the motor 11) caused by the layer short in the motor 11. That is, since the motor 11 and the drive circuit 2 are normally designed to have matching impedances, the impedance between the motor 11 and the drive circuit 2 is relatively matched. On the other hand, if a layer short occurs in the motor 11, the impedance mismatch between the motor 11 and the drive circuit 2 increases due to a change in the inductance of the motor 11. As a result, the frequency of the ringing generated in the voltage between the connecting lines Lu, Lv, and Lw changes. It has been confirmed that the frequency of the ringing after such a change is typically 1 MHz or higher. From the above, it can be said that an abnormal condition occurs when the frequency of the target high-frequency component is 1 MHz or higher.

[0041] When separating high frequencies of 1 MHz or higher using the high frequency separator 31, the following equation (1) is taken into consideration: In the following equation (1), L is inductance [H], and C is capacitance [F].

[0042]

[0043] According to the above formula (1), in consideration of the existing impedance in the power circuit, the capacitance of the LC circuit must be extremely small, and it is difficult to guide the superimposed high-frequency power of 1 MHz or more in the power circuit out of the circuit. Therefore, the superimposed high-frequency components must be detected by the analyzer 32 and fed back to the inverter circuit 22, and the configuration is limited to the high-frequency components separated by the high-frequency separator 31 being analyzed by the analyzer 32 and then controlled by the control circuit 6.

[0044] The inventors focused on the change in circuit constants resulting from the change in inductance of the motor 11, because the inductance of the motor 11 changes when a layer short occurs in the motor 11. For example, if a layer short occurs at the midpoint (50th turn) of a 100-winding coil, the inductance of the coil will be halved. In this case, the frequency of the high-frequency components of the motor 11 in its rated operating state will be approximately 1.41 times the frequency of the high-frequency components of the motor 11 in its normal rated operating state. The frequency of the high-frequency components of the motor 11 in its rated operating state is the frequency of the high-frequency components flowing through the connecting lines Lu, Lv, and Lw when the motor 11 is being operated at its rated operating state by the drive circuit 2. A normal state means that no layer short occurs. Considering the relationship between the location of the layer short in the motor 11's coil and the frequency of the high-frequency components of the motor 11 in its rated operating state, an abnormal condition can be defined as the frequency of the high-frequency components being 1.1 times or more the frequency of the high-frequency components of the motor 11 in its normal rated operating state.

[0045] In this embodiment, the abnormal condition may be at least one of the following: condition (1) that the frequency of the target high-frequency component is 1 MHz or higher; or condition (2) that the frequency of the target high-frequency component is 1.1 times or higher than the frequency of the high-frequency component in the rated operating state of the motor 11 under normal conditions. The abnormal condition may be satisfied when at least one of condition (1) or condition (2) is satisfied, or when both condition (1) and condition (2) are satisfied. The abnormal condition may be satisfied when condition (3) that the signal strength of the target high-frequency component is equal to or higher than a predetermined value. The predetermined value may be, for example, 3 dB when the signal strength is expressed as a voltage ratio. However, the predetermined value is not particularly limited and may be set appropriately so that the desired abnormality can be detected through experiments, simulations, or the like. The abnormal condition may be satisfied when at least one of conditions (1) to (3) is satisfied.

[0046] The first protection device 4 is provided to stop the output of AC output power. The first protection device 4 includes switches Su, Sv, and Sw interposed between the drive circuit 2 and the motor 11. The switches Su, Sv, and Sw are connected between the U-phase, V-phase, and W-phase input terminals of the motor 11 and the U-phase output terminals Pu, Pv, and Pw, respectively. The switches Su, Sv, and Sw may be controllable switches such as semiconductor switches or electromagnetic relays. When the switches Su, Sv, and Sw are closed in an on state, the first protection device 4 allows the output of AC output power from the drive circuit 2 to the motor 11, and when the switches Su, Sv, and Sw are open in an off state, the first protection device 4 stops the output of AC output power from the drive circuit 2 to the motor 11.

[0047] The second protection device 5 is provided to stop the input of input power. The second protection device 5 includes switches S1 and S2 interposed between the drive circuit 2 and the power supply 10. The switches S1 and S2 are respectively connected between the input terminal of the rectifier circuit 21a and the power supply 10. The switches S1 and S2 may be controllable switches such as semiconductor switches or electromagnetic relays. When the switches S1 and S2 are closed in an on state, the second protection device 5 allows the input of input power from the power supply 10 to the drive circuit 2, and when the switches S1 and S2 are open in an off state, the second protection device 5 stops the input of input power from the power supply 10 to the drive circuit 2.

[0048] The control circuit 6 may be realized, for example, by a computer system including at least one processor (microprocessor) and one or more memories. The computer system may also include one or more A / D converters. For example, the one or more A / D converters are used to convert the detected voltage from the state detection circuit 3 from analog to digital format. The control circuit 6 controls the drive circuit 2, the first protection device 4, and the second protection device 5. In particular, the control circuit 6 performs PWM control of a group of semiconductor switching elements of the inverter circuit 22 of the drive circuit 2 so that the drive circuit 2 operates the motor 11. More specifically, the control circuit 6 controls the switching of the semiconductor switching elements U1 to U4, V1 to V4, and W1 to W4 of the inverter circuit 22 of the drive circuit 2 so that the inverter circuit 22 supplies AC output power (three-phase AC power) to the motor 11 based on the DC output power from the smoothing circuit 21b.

[0049] The semiconductor switching elements U1 to U4 have three states: a first state in which the semiconductor switching elements U1 and U2 are on and the semiconductor switching elements U3 and U4 are off, a second state in which the semiconductor switching elements U3 and U4 are on and the semiconductor switching elements U1 and U2 are off, and a third state in which the semiconductor switching elements U2 and U3 are on and the semiconductor switching elements U1 and U4 are off. The voltage at the U-phase output terminal Pu is E / 2 in the first state, −E / 2 in the second state, and 0 in the third state.

[0050] The semiconductor switching elements V1 to V4 have three states: a first state in which the semiconductor switching elements V1 and V2 are on and the semiconductor switching elements V3 and V4 are off, a second state in which the semiconductor switching elements V3 and V4 are on and the semiconductor switching elements V1 and V2 are off, and a third state in which the semiconductor switching elements V2 and V3 are on and the semiconductor switching elements V1 and V4 are off. The voltage at the V-phase output terminal Pv is E / 2 in the first state, −E / 2 in the second state, and 0 in the third state.

[0051] The semiconductor switching elements W1 to W4 have three states: a first state in which the semiconductor switching elements W1 and W2 are on and the semiconductor switching elements W3 and W4 are off, a second state in which the semiconductor switching elements W3 and W4 are on and the semiconductor switching elements W1 and W2 are off, and a third state in which the semiconductor switching elements W2 and W3 are on and the semiconductor switching elements W1 and W4 are off. The voltage at the W-phase output terminal Pw is E / 2 in the first state, −E / 2 in the second state, and 0 in the third state.

[0052] In this way, the drive circuit 2 can provide voltages at five levels: E, E / 2, 0, −E / 2, and −E.

[0053] The control circuit 6 controls the switching of the semiconductor switching elements U1 to U4, V1 to V4, and W1 to W4 of the inverter circuit 22 of the drive circuit 2 based on, for example, U-phase, V-phase, and W-phase output voltage command values ​​corresponding to the sinusoidal AC voltages of the U-phase, V-phase, and W-phase of the three-phase AC, respectively, and on first and second carrier triangular waves. The frequencies of the first and second carrier triangular waves define the carrier frequency of the inverter circuit 22. The value of the first carrier triangular wave is equal to or greater than 0, and the value of the second carrier triangular wave is equal to or less than 0. The drive circuit 2 can apply five voltage levels: E, E / 2, 0, −E / 2, and −E, thereby making the voltage between the U-phase input terminal and the V-phase input terminal of the motor 11, the voltage between the V-phase input terminal and the W-phase input terminal of the motor 11, and the voltage between the W-phase input terminal and the U-phase input terminal of the motor 11 each closer to a sine wave.

[0054] The control circuit 6 functions as a processing circuit that determines whether an abnormality has occurred based on at least one of the frequency and signal strength output from the analyzer 32. The abnormality conditions can be a combination of the above-described conditions (1) to (3). For example, the processing circuit may determine whether an abnormality has occurred when the frequency of the target high-frequency component is 1 MHz or higher (condition (1)). The processing circuit may determine whether an abnormality has occurred when the frequency of the target high-frequency component is 1.1 times or higher than the frequency of the high-frequency component in the rated operating state of the motor 11 under normal conditions (condition (2)). The processing circuit may determine whether an abnormality has occurred when the signal strength of the target high-frequency component is equal to or higher than a predetermined value (condition (3)).

[0055] The control circuit 6 further stops or restricts the operation of the drive circuit 2 when the processing circuit (the control circuit 6 in this embodiment) determines an abnormality based on at least one of the frequency and signal strength output from the analyzer 32. In other words, in this embodiment, the control circuit 6 stops or restricts the operation of the drive circuit 2 when the frequency of the target high-frequency component is 1 MHz or higher. The process of determining the frequency of the target high-frequency component from the target high-frequency component can be performed in a much shorter time than, for example, the process using statistics described in Patent Document 1. This enables earlier detection of abnormalities.

[0056] The operation of the drive circuit 2 can be stopped by stopping the output of AC output power, stopping the output of DC output power, or stopping the input of input power. The operation of the drive circuit 2 can be limited by reducing the set value of the amplitude of the AC output power or reducing the set value of the frequency of the AC output power.

[0057] In this embodiment, the control circuit 6 sets the first protection device 4 to the OFF state to electrically isolate the motor 11 from the drive circuit 2 and stop the output of AC output power. To resume the output of AC output power, the control circuit 6 sets the first protection device 4 to the ON state to connect the motor 11 to the drive circuit 2.

[0058] In this embodiment, the control circuit 6 controls the drive circuit 2 to reduce the set value of the amplitude of the AC output power. In this embodiment, the drive circuit 2 can apply five levels of voltage: E, E / 2, 0, −E / 2, and −E, so the set value of the amplitude of the AC output power is changed from E to E / 2. In this case, the rotation speed of the motor 11 is lower than when the set value of the amplitude of the AC output power is E.

[0059] When the input of input power is stopped, the output of AC output power is stopped as a result. In this embodiment, the control circuit 6 sets the second protection device 5 to the OFF state to electrically isolate the power supply 10 from the drive circuit 2 and stop the output of AC output power. When the input of input power is resumed, the control circuit 6 sets the second protection device 5 to the ON state to connect the power supply 10 to the drive circuit 2.

[0060] The control circuit 6 stops or limits the operation of the drive circuit 2 in different ways depending on the number of times the frequency of the target high-frequency component satisfies the abnormal condition.

[0061] The control circuit 6 stops or restricts the operation of the drive circuit 2 in different ways depending on the time difference between the first time when the frequency of the target high-frequency component first satisfies the abnormal condition and the second time when the frequency of the target high-frequency component next satisfies the abnormal condition. In particular, the shorter the time difference, the more the control circuit 6 restricts the operation of the motor 11.

[0062] The process for stopping or restricting the operation of the motor 11 includes, for example, first to third processes. The first process is a process for stopping the output of AC output power and resuming the output of AC output power after a standby time has elapsed. The second process is a process for stopping the output of AC output power and operating the motor after a standby time has elapsed by reducing the set value of the amplitude of the AC output power. The third process is a process for stopping the output of AC output power and stopping the input of input power. Among the first to third processes, the degree of restriction on the operation of the motor 11 increases in the order of the third process, the second process, and the first process. Even in the first or second process, the longer the standby time, the higher the degree of restriction on the operation of the motor 11.

[0063] Next, an example of the operation of the control circuit 6 of the control device 1 will be briefly described with reference to Figures 3 to 8. Each of Figures 3 to 8 is a part of a flowchart of the operation of the control circuit 6 of the control device 1, and Figures 3 to 8 are combined to form a complete flowchart.

[0064] Referring to Figure 3, the control circuit 6 causes the drive circuit 2 to output AC output power to the motor 11 based on the input power of the power supply 10, thereby driving the motor 11. The control circuit 6 sets the number of abnormalities to 0 (S10). The number of abnormalities indicates the number of times an abnormality condition has been satisfied. The number of abnormalities is an indicator of the likelihood that an abnormality exists in the motor 11.

[0065] The control circuit 6 acquires the frequency of the target high frequency component from the state detection circuit 3 (S11). The control circuit 6 determines whether the frequency of the target high frequency component satisfies the abnormality condition (S12).

[0066] If the frequency of the target high frequency component does not satisfy the abnormal condition (S12: NO), the process returns to step S11. In steps S11 and S12, the control circuit 6 determines whether the frequency of the target high frequency component satisfies the abnormal condition at a predetermined period.

[0067] In step S12, if the frequency of the target high frequency component satisfies the abnormality condition (S12: YES), the control circuit 6 adds 1 to the number of abnormalities (S13), and determines whether the number of abnormalities is 1 or less (S14).

[0068] If the number of abnormalities is 1 or less in step S14 (S14: YES), the control circuit 6 sets the first protection device 4 to the OFF state and stops the output of AC output power (S15). The control circuit 6 determines whether a first standby time has elapsed since the output of AC output power was stopped (S16). The first standby time is, for example, 1 second. When the first standby time has elapsed (S16: YES), the control circuit 6 sets the first protection device 4 to the ON state and resumes the output of AC output power (S17), and resumes driving the motor 11 (S18). After that, the process returns to step S11.

[0069] In this way, when the frequency of the target high-frequency component satisfies the abnormal condition, the control circuit 6 stops the output of the AC output power. The control circuit 6 resumes the output of the AC output power when the first standby time has elapsed since the output of the AC output power was stopped.

[0070] If the number of abnormalities is not equal to or less than 1 in step S14 (S14: NO), referring to FIG. 4, the control circuit 6 determines whether the time difference between the first time when the frequency of the target high-frequency component first satisfied the abnormal condition and the second time when the frequency of the target high-frequency component next satisfied the abnormal condition is within a first predetermined time (step S19). The shortness of this time difference is an indicator of the likelihood of an abnormality in the motor 11. The first predetermined time is, for example, approximately 100 times the period corresponding to the reference frequency of the inverter circuit 22, or approximately 20 to 100 ms.

[0071] In step S19, if the time difference is within the first predetermined time (step S19: YES), the control circuit 6 sets the first protection device 4 to the OFF state to stop the output of AC output power (S20). The control circuit 6 sets the second protection device 5 to the OFF state to stop the input of input power (S21). The control circuit 6 outputs a first abnormality notification (S22). The first abnormality notification indicates that there is a very high possibility that an abnormality has occurred in the motor 11. The first abnormality notification is output to, for example, an external terminal. After this, the control circuit 6 stops driving the motor 11 (S23).

[0072] In this way, if the frequency of the target high-frequency component satisfies the abnormal condition (S19: YES) before a predetermined time (first predetermined time) has elapsed since the output of AC output power was resumed after the first waiting time had elapsed (S17), the control circuit 6 stops the output of AC output power (S20) and stops the input of input power (S21).

[0073] If the time difference is not within the first predetermined time in step S19 (step S19: NO), referring to Fig. 5, the control circuit 6 determines whether the time difference is within a second predetermined time that is longer than the first predetermined time (step S24). The second predetermined time is, for example, about 1000 times the period corresponding to the reference frequency of the inverter circuit 22, and is about 200 ms to 1 s.

[0074] In step S25, if the time difference is within the second predetermined time (step S24: YES), the control circuit 6 sets the first protection device 4 to the OFF state and stops the output of AC output power (S25). The control circuit 6 changes the switching control of the semiconductor switching elements of the drive circuit 2 so that the set value of the amplitude of the AC output power decreases from E to E / 2 (S26). The control circuit 6 outputs a second abnormality notification (S27). The second abnormality notification indicates that there is a high possibility that an abnormality has occurred in the motor 11. The second abnormality notification is output to, for example, an external terminal.

[0075] The control circuit 6 determines whether a fourth standby time has elapsed since the output of the AC output power was stopped (S28, which is longer than the first standby time. The fourth standby time is, for example, 60 seconds). When the fourth standby time has elapsed (S28: YES), as shown in FIG. 6 , the control circuit 6 sets the first protection device 4 to the ON state to resume the output of the AC output power (S29), and resumes driving the motor 11 (S30). In this case, the set value of the amplitude of the AC output power remains lowered from E to E / 2.

[0076] In this way, if the frequency of the target high-frequency component satisfies the abnormality condition before a predetermined time (second predetermined time) has elapsed since the output of the AC output power was resumed after the first standby time (S17), the control circuit 6 stops the output of the AC output power (S25) and reduces the set value of the amplitude of the AC output power (S26).When a fourth standby time longer than the first standby time has elapsed since the output of the AC output power was stopped, the control circuit 6 resumes the output of the AC output power while keeping the set value of the amplitude of the AC output power reduced (S29).

[0077] Thereafter, the control circuit 6 acquires the frequency of the target high frequency component from the state detection circuit 3 (S31). The control circuit 6 determines whether the frequency of the target high frequency component satisfies the abnormality condition (S32).

[0078] In step S32, if the frequency of the target high frequency component satisfies the abnormal condition (S32: YES), the control circuit 6 proceeds to step S20 in FIG.

[0079] In step S32, if the frequency of the target high-frequency component does not satisfy the abnormal condition (S32: NO), the control circuit 6 determines whether the second monitoring time has elapsed since the driving of the motor 11 was restarted (S33).

[0080] In step S33, if the second monitoring time has elapsed since the restart of driving of the motor 11 (S33: YES), the control circuit 6 cancels the reduction in the set value of the amplitude of the AC output power, returns the set value of the amplitude of the AC output power to E (S34), and proceeds to step S11 in FIG. 3.

[0081] In step S33, if the second monitoring time has not elapsed since the driving of the motor 11 was restarted (S33: NO), the process returns to step S31.

[0082] In steps S31 to S33, if the frequency of the target high-frequency component satisfies the abnormal condition between the time when the motor 11 is restarted and the time when the second monitoring time has elapsed, the process proceeds to step S20 in FIG. 4, and if the frequency of the target high-frequency component does not satisfy the abnormal condition between the time when the motor 11 is restarted and the time when the second monitoring time has elapsed, the process proceeds to step S34.

[0083] In this way, if the frequency of the target high-frequency component does not satisfy the abnormal condition during the second monitoring time from when the output of AC output power is resumed after the fourth waiting time has elapsed (S29) (YES at S33), the control circuit 6 cancels the reduction in the set value of the amplitude of the AC output power (S34).If the frequency of the target high-frequency component satisfies the abnormal condition before the second monitoring time has elapsed from when the output of AC output power is resumed after the fourth waiting time has elapsed (S29) (YES at S32), the control circuit 6 stops the output of AC output power (S20) and stops the input of input power (S21).

[0084] 5, if the time difference is not within the second predetermined time in step S24 (step S24: NO), referring to Fig. 7, the control circuit 6 determines whether the time difference is within a third predetermined time that is longer than the second predetermined time (step S35). The third predetermined time is, for example, about 10,000 times the period corresponding to the reference frequency of the inverter circuit 22, which is about 2 seconds to 10 seconds.

[0085] In step S35, if the time difference is not within the third predetermined time (step S35: NO), the process returns to step S10, and the control circuit 6 sets the number of abnormalities to 0 (see FIG. 3). In other words, if a sufficient amount of time has passed since the abnormality was detected, it is considered that there is a possibility of erroneous detection, so the number of abnormalities is reset to 0.

[0086] In step S35, if the time difference is within the third predetermined time (step S35: YES), the control circuit 6 determines whether the number of abnormalities is 2 or less (S36).

[0087] If the number of abnormalities is two or less in step S36 (S36: YES), the control circuit 6 sets the first protection device 4 to the OFF state and stops the output of AC output power (S37). The control circuit 6 outputs a third abnormality notification (S38). The third abnormality notification indicates that there is a possibility of an abnormality in the motor 11. The third abnormality notification is output, for example, to an external terminal. The control circuit 6 determines whether a second waiting time has elapsed since the output of AC output power was stopped (S39). The second waiting time is longer than the first waiting time. The second waiting time is, for example, 10 seconds. When the second waiting time has elapsed (S39: YES), the control circuit 6 sets the first protection device 4 to the ON state and resumes the output of AC output power (S40), thereby resuming the drive of the motor 11 (S41). Then, the process returns to step S11.

[0088] In this way, if the frequency of the target high-frequency component satisfies the abnormality condition before a predetermined time (third predetermined time) has elapsed since the output of AC output power was resumed after the first standby time had elapsed (S17), the control circuit 6 stops the output of AC output power. The control circuit 6 resumes the output of AC output power when a second standby time, which is longer than the first standby time, has elapsed since the output of AC output power was stopped (S40).

[0089] In step S36, if the number of abnormalities is not two or less (S36: NO), that is, if the number of abnormalities is three or more, the control circuit 6 sets the first protection device 4 to the off state and stops the output of AC output power (S42). The control circuit 6 changes the switching control of the semiconductor switching elements of the drive circuit 2 so that the set value of the amplitude of the AC output power decreases from E to E / 2 (S43). The control circuit 6 outputs a second abnormality notification (S44).

[0090] The control circuit 6 determines whether a third waiting time has elapsed since the output of the AC output power was stopped (S45). The third waiting time is longer than the second waiting time. The third waiting time is, for example, 60 seconds. When the third waiting time has elapsed (S45: YES), as shown in FIG. 8 , the control circuit 6 sets the first protection device 4 to the ON state, resumes the output of the AC output power (S46), and resumes driving the motor 11 (S47). In this case, the set value of the amplitude of the AC output power remains reduced from E to E / 2.

[0091] In this way, if the frequency of the target high-frequency component satisfies the abnormality condition before a predetermined time (third predetermined time) has elapsed since the output of the AC output power was resumed after the second standby time (S40), the control circuit 6 stops the output of the AC output power (S42) and reduces the set value of the amplitude of the AC output power (S43).When a third standby time, which is longer than the second standby time, has elapsed since the output of the AC output power was stopped, the control circuit 6 resumes the output of the AC output power while keeping the set value of the amplitude of the AC output power reduced (S46).

[0092] Thereafter, the control circuit 6 acquires the frequency of the target high frequency component from the state detection circuit 3 (S48). The control circuit 6 determines whether the detected voltage is less than the second voltage (S49).

[0093] In step S51, if the frequency of the target high frequency component satisfies the abnormal condition (S49: YES), the control circuit 6 proceeds to step S20 in FIG.

[0094] If the frequency of the target high-frequency component does not satisfy the abnormal condition in step S49 (S49: NO), the control circuit 6 determines whether the first monitoring time has elapsed since the restart of driving the motor 11 (S50). The first monitoring time may be the same as or different from the second monitoring time in step S33.

[0095] In step S50, if the first monitoring time has elapsed since the restart of driving of the motor 11 (S50: YES), the control circuit 6 cancels the reduction in the set value of the amplitude of the AC output power, returns the set value of the amplitude of the AC output power to E (S51), and proceeds to step S11 in FIG. 3.

[0096] In step S50, if the first monitoring time has not elapsed since the driving of the motor 11 was restarted (S50: NO), the process returns to step S48.

[0097] In steps S47 to S50, if the frequency of the target high-frequency component satisfies the abnormal condition between the time when the motor 11 is restarted and the time when the first monitoring time has elapsed, the process proceeds to step S20 in FIG. 4; if the frequency of the target high-frequency component does not satisfy the abnormal condition between the time when the motor 11 is restarted and the time when the first monitoring time has elapsed, the process proceeds to step S51.

[0098] In this way, if the frequency of the target high-frequency component does not satisfy the abnormal condition during the first monitoring time from when the output of the AC output power is resumed after the third waiting time has elapsed (S46) (YES at S50), the control circuit 6 cancels the reduction in the set value of the amplitude of the AC output power (S51). If the frequency of the target high-frequency component satisfies the abnormal condition before the first monitoring time has elapsed from when the output of the AC output power is resumed after the third waiting time has elapsed (S46) (YES at S49), the control circuit 6 stops the output of the AC output power (S20) and stops the input of the input power (S21).

[0099] [1.1.2 Effects, etc.] The control device 1 described above controls a refrigeration cycle apparatus and includes a state detection circuit 3 and a control circuit 6 that controls a drive circuit 2 that drives a motor 11 of a compressor of the refrigeration cycle apparatus. The state detection circuit 3 includes a high-frequency separator 31 that separates target high-frequency components higher than the carrier frequency of the inverter circuit 22 from an electrical signal passing through connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 and the motor 11, and an analyzer 32 that outputs at least one of the frequency and signal strength of the target high-frequency components from the target high-frequency components separated by the high-frequency separator 31. The control circuit 6 stops or limits operation of the drive circuit 2 when it determines that the state of the refrigeration cycle apparatus is unsteady based on at least one of the frequency and signal strength output from the analyzer 32. This configuration enables earlier detection of the state (particularly the state of the refrigeration cycle apparatus).

[0100] In the state detection circuit 3, the high-frequency separator 31 is connected between the connection lines Lu, Lv, Lw and the analyzer 32, and includes high-pass filters 311a, 311b, 311c that pass the target high-frequency components. This configuration enables early state detection.

[0101] In the state detection circuit 3, the analyzer 32 obtains the frequency of the target high-frequency component by performing a fast Fourier transform on the target high-frequency component separated by the high-frequency separator 31. This configuration makes it possible to reduce the time required for the process of obtaining the frequency of the target high-frequency component.

[0102] In the state detection circuit 3, the processing circuit (control circuit 6) determines that the state is unsteady when the frequency of the target high frequency component is 1 MHz or higher. This configuration makes it possible to improve the accuracy of state detection.

[0103] In the state detection circuit 3, the processing circuit (control circuit 6) determines that the state is unsteady when the frequency of the target high-frequency component is 1.1 times or more the frequency of the high-frequency component in the rated operating state of the motor 11 under normal conditions. This configuration makes it possible to improve the accuracy of state detection.

[0104] The above-described state detection circuit 3 detects the state of the refrigeration cycle apparatus, and includes a high-frequency separator 31 that separates target high-frequency components higher than the carrier frequency of the inverter circuit 22 from an electrical signal passing through connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 that drives the motor 11 of the compressor of the refrigeration cycle apparatus and the motor 11, an analyzer 32 that outputs at least one of the frequency and signal strength of the target high-frequency component from the target high-frequency component separated by the high-frequency separator 31, and a processing circuit (control circuit 6) that determines the state of the refrigeration cycle apparatus based on at least one of the frequency and signal strength output from the analyzer 32. This configuration enables earlier detection of the state (particularly the state of the refrigeration cycle apparatus).

[0105] It can be said that the above-described state detection circuit (abnormality detection circuit) 3 executes the following state detection method (abnormality detection method). The state detection method acquires target high-frequency components higher than the carrier frequency of the inverter circuit 22, which are separated from an electrical signal passing through connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 that drives the motor 11 of the compressor of the refrigeration cycle apparatus, and the motor 11, outputs at least one of the frequency and signal strength of the target high-frequency component based on the target high-frequency component, and determines the state of the refrigeration cycle apparatus based on at least one of the frequency and signal strength. This configuration enables early detection of the state.

[0106] The control device 1 described above can be said to execute the following control method. The control method acquires target high-frequency components higher than the carrier frequency of the inverter circuit 22, which are separated from an electrical signal passing through connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 that drives the motor 11 of the compressor of the refrigeration cycle apparatus, and the motor 11; outputs at least one of the frequency and signal strength of the target high-frequency components from the target high-frequency components; and stops or restricts operation of the drive circuit 2 when it is determined that the state of the refrigeration cycle apparatus is unsteady based on at least one of the frequency and signal strength. This configuration enables earlier detection of the state and improves safety.

[0107] The state detection method executed by the state detection circuit 3 can be realized by a computer system executing a program. This program is a program for causing a computer system to execute the state detection method. This configuration enables early detection of the state.

[0108] The control method executed by the control circuit 6 can be realized by a computer system executing a program. This program is a program for causing the computer system to execute the control method. This configuration enables early detection of the condition.

[0109] [2. Modifications] The embodiments of the present disclosure are not limited to the above-described embodiments. The above-described embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the above-described embodiments are listed below. The modifications described below can be applied in appropriate combinations.

[0110] In one modification, the configuration of the state detection circuit is not limited to the configuration of the above embodiment.

[0111] 9 to 12 are schematic circuit diagrams of a state detection circuit according to a modified example, in which the processing circuit (control circuit 6) is omitted.

[0112] The state detection circuit 3A shown in FIG. 9 includes a high frequency separator 31A and an analyzer 32.

[0113] The high-frequency separator 31A includes high-pass filters 311d, 311e, and 311f. The high-pass filters 311d, 311e, and 311f are connected between the connecting lines Lu, Lv, and Lw and the analyzer 32, respectively. The high-pass filters 311a, 311b, and 311c pass high-frequency components higher than the carrier frequency of the inverter circuit 22. The high-pass filters 311d, 311e, and 311f include resistors R34, R35, and R36 inserted in the connecting lines Lu, Lv, and Lw, respectively, and capacitors C34, C35, and C36 connected between the ends of the resistors R34, R35, and R36 on the motor 11 side and the analyzer 32, respectively. The capacitances of the capacitors C34, C35, and C36 are set so as to pass high-frequency components higher than the carrier frequency of the inverter circuit 22.

[0114] These high-pass filters 311d, 311e, and 311f are RC types. If necessary, the high-pass filters 311d, 311e, and 311f of the high-frequency separator 31A may be configured with more stages, such as a two-stage RCRC, a three-stage RCRCRC, or a four-stage RCRCRCRC. The RC-type high-pass filters 311d to 311f enable the high-frequency separator 31A to be realized with a simpler configuration, enabling lower costs than the LC-type high-pass filters 311a to 311c. In the case of the LC type, as with the RC type, the high-pass filters 311a to 311c may be configured with more stages, such as a two-stage LCLC, a three-stage LCLCLC, or a four-stage LCLCLCLC, if necessary.

[0115] The state detection circuit 3B shown in FIG. 10 includes a high frequency separator 31B and an analyzer 32.

[0116] The high-frequency separator 31B includes high-pass filters 311g, 311h, and 311i. Similar to the high-pass filters 311a, 311b, and 311c, the high-pass filters 311g, 311h, and 311i include inductors L31, L32, and L33 and capacitors C31, C32, and C32, respectively. However, in the high-pass filters 311g, 311h, and 311i, the capacitors C31, C32, and C33 are connected between the analyzer 32 and the ends of the inductors R31, R32, and R32, respectively, that are located on the driver circuit 2 side.

[0117] Like the high-frequency separator 31, the high-frequency separator 31B separates target high-frequency components higher than the carrier frequency of the inverter circuit 22 from the electrical signals passing through the connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 that drives the motor 11 and the motor 11.

[0118] The state detection circuit 3C shown in FIG. 11 includes a high frequency separator 31C and an analyzer 32.

[0119] The high-frequency separator 31C includes high-pass filters 311j, 311k, and 311l. Similar to the high-pass filters 311d, 311e, and 311f, the high-pass filters 311j, 311k, and 311l include resistors R34, R35, and R36 and capacitors C34, C35, and C36, respectively. However, in the high-pass filters 311j, 311k, and 311l, the capacitors C34, C35, and C36 are connected between the analyzer 32 and the ends of the resistors R34, R35, and R36 on the driver circuit 2 side, respectively.

[0120] Like the high-frequency separator 31A, the high-frequency separator 31C separates target high-frequency components higher than the carrier frequency of the inverter circuit 22 from the electrical signals passing through the connection lines Lu, Lv, and Lw between the inverter circuit 22 of the drive circuit 2 that drives the motor 11 and the motor 11.

[0121] The high-frequency separator 31 does not necessarily have to include all of the high-pass filters 311a, 311b, and 311c, but only needs to include one or more of the high-pass filters 311a, 311b, and 311c. Similarly, the high-frequency separator 31A does not necessarily have to include all of the high-pass filters 311d, 311e, and 311f, but only needs to include one or more of the high-pass filters 311d, 311e, and 311f. This also applies to the high-frequency separators 31B and 31C.

[0122] The high-frequency separator 31 is not necessarily limited to a configuration including a high-pass filter. The high-frequency separator 31 may include a band-pass filter instead of a high-pass filter. The high-frequency separator 31 only needs to be able to separate target high-frequency components higher than the carrier frequency of the inverter circuit 22 from the electrical signals passing through the connection lines Lu, Lv, and Lw.

[0123] The state detection circuit 3D shown in FIG. 12 includes a high-frequency separator 31 and an analyzer 32D. The analyzer 32D is configured with an analog circuit. The analyzer 32D also includes an integrating circuit 321 and an operational amplifier 322. The integrating circuit 321 is connected to the high-frequency separator 31 and receives the target high-frequency component separated by the high-frequency separator 31. The operational amplifier 322 is connected to the output of the integrating circuit 321. The operational amplifier 322 amplifies the voltage of the output from the integrating circuit 321 to output a voltage signal indicating the signal strength of the target high-frequency component. In this way, the analyzer 32D inputs the target high-frequency component separated by the high-frequency separator 31 to the integrating circuit 321 and voltage-amplifies the output of the integrating circuit 321 using the operational amplifier 322, thereby outputting a signal indicating the signal strength of the target high-frequency component when the target high-frequency component increases.

[0124] In one variant, the processing circuitry does not have to be implemented by the control circuitry 6, but may be implemented by a computer system separate from the control circuitry 6. Alternatively, the analyzer 32 and the processing circuitry may be implemented by a single computer system. Alternatively, the analyzer 32, the processing circuitry, and the control circuitry 6 may be implemented by a single computer system.

[0125] In one modified example, in the control circuit 6, stopping the operation of the drive circuit 2 may include one or more of stopping the output of AC output power, stopping the output of DC output power, or stopping the input of input power. Restricting the operation of the drive circuit 2 may include one or more of reducing the set value of the amplitude of the AC output power or reducing the set value of the frequency of the AC output power.

[0126] In one modified example, the control circuit 6 may stepwise stop or decelerate the motor 11. As an example, the control circuit 6 may stepwise reduce at least one of the amplitude and frequency of the AC output power, thereby stepwise reducing the effective value of the AC output power supplied to the motor 11.

[0127] In this modification, the operation of the control circuit 6 is not necessarily limited to the operations shown in the flowcharts of Figures 3 to 8. The flowcharts shown in Figures 3 to 8 are merely examples.

[0128] For example, the processing of steps S20 to S23, i.e., the processing of stopping the output of AC output power and stopping the input of input power, is not essential in the operation of the control circuit 6. The processing of steps S25 to S28, i.e., the processing of stopping the output of AC output power and reducing the set value of the amplitude of the AC output power after the standby time has elapsed, is not essential in the operation of the control circuit 6. Similarly, the processing of steps S30 to S34, steps S35 to S41, or steps S42 to S51 is not essential in the operation of the control circuit 6.

[0129] The control circuit 6 does not necessarily have to stop or restrict the operation of the drive circuit 2 in different ways depending on the time difference between the first time when the frequency of the target high-frequency component first satisfies the abnormal condition and the second time when the frequency of the target high-frequency component next satisfies the abnormal condition, or the number of times the frequency of the target high-frequency component satisfies the abnormal condition.

[0130] In one modified example, the first protection device 4 is not limited to a circuit configuration including the switches Su, Sv, and Sw, and may include a circuit configuration that adjusts the magnitude of the AC output power, for example, the magnitude of the voltage, output from the drive circuit 2 to the motor 11. The first protection device 4 may be disposed within the drive circuit 2.

[0131] In one modified example, the second protection device 5 is not limited to a circuit configuration including the switches S1 and S2, and may include a circuit configuration that adjusts the magnitude of the input power, for example, the magnitude of the voltage, input from the power source 10 to the drive circuit 2. The second protection device 5 may be disposed within the drive circuit 2.

[0132] In one modified example, the control device 1 does not necessarily include both the first protection device 4 and the second protection device 5, and may include either the first protection device 4 or the second protection device 5, or the first and second protection devices 4, 5 may be omitted if the drive circuit 2 has a function of adjusting the AC output power. For example, the control circuit 6 may stop the output of AC output power to the motor 11 by turning on the semiconductor switching elements V1 to V4 of the inverter circuit 22 and turning off the remaining semiconductor switching elements U1 to U4, W1 to W4. In this case, the first protection device 4 may be omitted.

[0133] FIG. 13 shows a modified control device 1E. In FIG. 13, the control device 1E includes a third protection device 7. The third protection device 7 is provided to stop the output of DC output power. The third protection device 7 includes switches S3, S4, and S5 interposed between the converter circuit 21 and the inverter circuit 22 of the drive circuit 2. The switch S3 is commonly connected between the first output point P1 and the semiconductor switching elements U1, V1, and W1. The switch S4 is commonly connected between the second output point P2 and the semiconductor switching elements U4, V4, and W4. The switch S5 is commonly connected between the third output point P3 and the connection point between diodes D5 and D6, the connection point between diodes D7 and D8, and the connection point between diodes D9 and D10. The switches S3, S4, and S5 may be controllable switches such as semiconductor switches or electromagnetic relays. When the switches S3, S4, and S5 are closed in the on state, the third protection device 7 allows the output of DC output power from the converter circuit 21 to the inverter circuit 22, and when the switches S3, S4, and S5 are open in the off state, the third protection device 7 stops the output of DC output power from the converter circuit 21 to the inverter circuit 22.

[0134] When stopping the output of power to the motor 11, the safety level increases in the order of stopping the input of input power, stopping the output of DC output power, and stopping the output of AC output power. Therefore, after the operation of the first protection device 4, the third protection device 7 may be operated before the operation of the second protection device 5. Note that if the third protection device 7 is present, the second protection device 5 may be omitted.

[0135] In one variant, the third protection device 7 is not limited to a circuit configuration including switches S3, S4, and S5, but may include a circuit configuration that adjusts the magnitude of the DC output power, for example, the magnitude of the voltage, output from the converter circuit 21 to the inverter circuit 22.

[0136] In one variant, the power supply 10 may be any of a variety of AC power sources, particularly a commercial power source. Although the voltage and frequency of the commercial power source vary depending on the country, the drive circuit 2 may be configured to be able to drive the motor 11 using any of a variety of commercial power sources.

[0137] In one modified example, the drive circuit 2 may be configured to supply AC output power corresponding to the type of the motor 11. The AC output power is not limited to three-phase AC power, but may be single-phase AC power.

[0138] In one variation, the converter circuit 21 may have a plurality of third output points. The plurality of third output points may output different voltages. The inverter circuit 22 may have a plurality of third semiconductor switching element groups connected between the plurality of third output points and the motor 11. If the total number of the first output point P1, the second output point P2, and the plurality of third output points P3 is n, the drive circuit 2 can provide voltages at (2×n−1) levels. By increasing n, the voltage waveform applied to the motor 11 by the drive circuit 2 can be made closer to a sine wave.

[0139] In one modified example, the circuit configuration of the inverter circuit 22 is not limited to the circuit configuration shown in FIG. 1. The circuit configuration of the inverter circuit 22 shown in FIG. 1 is a so-called NPC (Neutral-Point-Clamped) type, but may also be an A-NPC (Advanced-NPC) type. The inverter circuit 22 may have multiple semiconductor switching element groups connected between multiple output points with different voltages and the electric motor. The multiple semiconductor switching elements constituting the multiple semiconductor switching element groups may include semiconductor switching elements that are common to two or more semiconductor switching element groups. The inverter circuit 22 does not necessarily have to be a multilevel inverter.

[0140] The motor 11 may be used in various devices, including, but not limited to, electric vehicles (electric automobiles, etc.), home appliances (washing machines, electric fans, air conditioners, etc.), power tools, control devices, etc. As an example, the motor 11 may be used in a compressor of a refrigeration cycle device used in an air conditioner, etc. In recent years, from the perspective of preventing global warming, working fluids with lower GWPs, such as 1,1,2-trifluoroethylene (HFO1123) and 1,2-difluoroethylene (HFO1132), have been used as working fluids in refrigeration cycle devices. HFO1123 and HFO1132 have lower GWPs than the conventionally widely used R410A, but this makes them less stable than R410A. For example, the generation of radicals may cause a disproportionation reaction of HFO1123 or HFO1132 to proceed, potentially converting HFO1123 and HFO1132 into different compounds. The causes of the disproportionation reaction of the working fluid are thought to be heat and radicals. For example, it is thought that the disproportionation reaction of the working fluid progresses when radicals are generated under high temperature and high pressure. Radicals may be generated, for example, by a discharge phenomenon that may occur when a layer short occurs in the compressor motor. Here, the state detection circuit 3 of this embodiment enables early detection of a motor abnormality (layer short). In other words, using the state detection circuit 3 in the compressor motor enables early detection of a sign of the disproportionation reaction of the working fluid. If the sign of the disproportionation reaction of the working fluid can be detected earlier, the disproportionation reaction can be suppressed earlier, thereby improving the suppression of the disproportionation reaction.

[0141] [3. Aspects] As is clear from the above-described embodiment and modifications, the present disclosure includes the following aspects.

[0142] [Aspect 1] A control device for controlling a refrigeration cycle device, comprising: a control circuit that controls a drive circuit that drives a motor of a compressor of the refrigeration cycle device; wherein the state detection circuit comprises: a high frequency separator that separates target high frequency components higher than a carrier frequency of the inverter circuit from an electrical signal passing through a connection line between an inverter circuit of the drive circuit and the motor; and an analyzer that outputs at least one of a frequency and a signal strength of the target high frequency components from the target high frequency components separated by the high frequency separator; and wherein the control circuit stops or limits operation of the drive circuit when it determines that the state of the refrigeration cycle device is unsteady based on at least one of the frequency and the signal strength output from the analyzer.

[0143] [Aspect 2] The state detection circuit of Aspect 1, wherein the high-frequency separator includes a high-pass filter connected between the connection line and the analyzer, and passing high-frequency components of the target.

[0144] [Aspect 3] The state detection circuit of Aspect 1 or 2, wherein the analyzer performs a fast Fourier transform on the high frequency component of the target separated by the high frequency separator to obtain the frequency of the high frequency component of the target.

[0145] [Aspect 4] The state detection circuit of Aspect 1, wherein the high-frequency separator includes a band-pass filter connected between the connection line and the analyzer and passing high-frequency components of the target.

[0146] [Aspect 5] The state detection circuit of Aspect 4, wherein the analyzer includes: an integrating circuit to which the high-frequency components of the target separated by the high-frequency separator are input; and an operational amplifier that amplifies the voltage of the output from the integrating circuit to output a voltage signal indicating the signal strength of the high-frequency components of the target.

[0147] [Aspect 6] The state detection circuit according to any one of Aspects 1 to 5, wherein the control circuit determines that the state is unsteady when the frequency of the high frequency component of the target is 1 MHz or higher.

[0148] [Aspect 7] The state detection circuit according to any one of Aspects 1 to 5, wherein the control circuit determines that the state is unsteady when the frequency of the high frequency component of the target is 1.1 times or more the frequency of the high frequency component in a rated operating state of the motor under normal conditions.

[0149] [Aspect 8] A state detection circuit for detecting a state of a refrigeration cycle device, comprising: a high frequency separator for separating target high frequency components higher than a carrier frequency of an inverter circuit from an electrical signal passing through a connection line between an inverter circuit of a drive circuit that drives a motor of a compressor of the refrigeration cycle device and the motor; an analyzer for outputting at least one of a frequency and a signal strength of the target high frequency components from the target high frequency components separated by the high frequency separator; and a processing circuit for determining a state of the refrigeration cycle device based on at least one of the frequency and the signal strength output from the analyzer.

[0150] [Aspect 9] A state detection method comprising: acquiring a target high-frequency component higher than a carrier frequency of an inverter circuit separated from an electrical signal passing through a connection line between an inverter circuit of a drive circuit that drives a compressor motor of a refrigeration cycle device and the motor; outputting at least one of a frequency and a signal strength of the target high-frequency component based on the target high-frequency component; and determining a state of the refrigeration cycle device based on at least one of the frequency and the signal strength.

[0151] [Aspect 10] A control method comprising: acquiring a target high-frequency component higher than a carrier frequency of an inverter circuit, which is separated from an electrical signal passing through a connection line between an inverter circuit of a drive circuit that drives a motor of a compressor of a refrigeration cycle device and the motor; outputting at least one of a frequency and a signal strength of the target high-frequency component from the target high-frequency component; and stopping or restricting operation of the drive circuit when it is determined that the state of the refrigeration cycle device is unsteady based on at least one of the frequency and the signal strength.

[0152] [Aspect 11] A program for causing a computer system to execute the state detection method of aspect 9.

[0153] [Aspect 12] A program for causing a computer system to execute the control method of aspect 10.

[0154] Aspects 2 to 7 are optional elements and are not essential. Aspects 2 to 7 can be appropriately combined with Aspect 9 or 10.

[0155] The present disclosure is applicable to a control device, a state detection circuit, a state detection method, a control method, and a program. Specifically, the present disclosure is applicable to a control device, a state detection circuit, a state detection method, a control method, and a program (computer program, computer program product) for executing the state detection method or the control method that detects the state of a refrigeration cycle device.

[0156] REFERENCE SIGNS LIST 1, 1E Control device 2 Drive circuit 21 Converter circuit 22 Inverter circuit 3, 3A, 3B, 3C, 3D State detection circuit 31 High frequency separator 32, 32A, 32B, 32C, 32D Analyzer 4 First protection device 5 Second protection device 6 Control circuit (processing circuit) 10 Power supply 11 Motor

Claims

1. A control device for controlling a refrigeration cycle apparatus, comprising: a state detection circuit; and a control circuit for controlling a drive circuit for driving a motor of a compressor of the refrigeration cycle apparatus, wherein the state detection circuit comprises: a high frequency separator for separating target high frequency components higher than a carrier frequency of the inverter circuit from an electrical signal passing through a connecting line between an inverter circuit of the drive circuit and the motor; and an analyzer for outputting at least one of a frequency and a signal strength of the target high frequency component from the target high frequency components separated by the high frequency separator, wherein the control circuit stops or limits operation of the drive circuit when it determines that the state of the refrigeration cycle apparatus is unsteady based on at least one of the frequency and the signal strength output from the analyzer.

2. The control device of claim 1, wherein the high-frequency separator is connected between the connection line and the analyzer and includes a high-pass filter that passes high-frequency components of the target.

3. The control device according to claim 1, wherein the analyzer performs a fast Fourier transform on the high frequency components of the target separated by the high frequency separator to obtain the frequency of the high frequency components of the target.

4. The control device of claim 1, wherein the high-frequency separator includes a band-pass filter connected between the connection line and the analyzer and passing high-frequency components of the target.

5. The control device of claim 4, wherein the analyzer includes: an integrating circuit to which the high frequency components of the target separated by the high frequency separator are input; and an operational amplifier which outputs a voltage signal indicating the signal strength of the high frequency components of the target by amplifying the voltage of the output from the integrating circuit.

6. The control device according to claim 1, wherein the control circuit determines that the target is in the unsteady state when the frequency of the high frequency component of the target is 1 MHz or higher.

7. The control device according to claim 1, wherein said control circuit judges said non-steady state to be occurring when the frequency of the high frequency component of said target is 1.1 times or more the frequency of the high frequency component of said motor in a normal rated operating state.

8. A status detection circuit for detecting a status of a refrigeration cycle device, comprising: a high frequency separator for separating target high frequency components higher than a carrier frequency of an inverter circuit from an electrical signal passing through a connecting line between an inverter circuit of a drive circuit for driving a motor of a compressor of the refrigeration cycle device and the motor; an analyzer for outputting at least one of a frequency and a signal strength of the target high frequency components from the target high frequency components separated by the high frequency separator; and a processing circuit for determining a status of the refrigeration cycle device based on at least one of the frequency and the signal strength outputted from the analyzer.

9. A status detection method comprising: acquiring a target high-frequency component higher than a carrier frequency of an inverter circuit separated from an electrical signal passing through a connecting line between an inverter circuit of a drive circuit that drives a motor of a compressor of a refrigeration cycle device and the motor; outputting at least one of a frequency and a signal strength of the target high-frequency component based on the target high-frequency component; and determining a status of the refrigeration cycle device based on at least one of the frequency and the signal strength.

10. A control method comprising: acquiring a target high-frequency component higher than the frequency of the high-frequency component in the rated operating state of the motor, separated from an electrical signal passing through a connecting line between a drive circuit that drives a motor of a compressor of a refrigeration cycle device and the motor; outputting at least one of the frequency and signal strength of the target high-frequency component from the target high-frequency component; and stopping or restricting operation of the drive circuit when it is determined that the state of the refrigeration cycle device is non-steady based on at least one of the frequency and the signal strength.

11. A program for causing a computer system to execute the state detection method of claim 9.

12. A program for causing a computer system to execute the control method of claim 10.

Images