Control device, electric compressor, and method and program for detecting ripple voltage

Abstract

To provide a method for detecting ripple voltage.SOLUTION: A control device comprises: an acquisition unit which samples voltage values of input voltage of a battery-driven motor compressor at unequal intervals; and a waveform calculation unit which assumes a sine wave as a waveform of a ripple component of the input voltage and calculates the waveform by fitting the sine wave so that a value of the sine wave at time corresponding to the voltage values sampled at the unequal intervals approximates the voltage values at the time of each.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a control device, an electric compressor, and a method and program for detecting ripple voltage. [Background technology]

[0002] One of the components of a car air conditioner installed in a vehicle is an electric compressor. Ripple voltage can occur in the drive circuit that drives the electric compressor. When the ripple voltage becomes large, resonance occurs and an excessive current flows.

[0003] Patent Document 1 discloses a technique for detecting the ripple voltage of an automotive AC generator, and determining that the AC generator has failed if the difference between the maximum and minimum values ​​of the ripple voltage exceeds a predetermined value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-135393 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to protect the electric compressor from excessive current caused by resonance of the ripple voltage, it is necessary to be able to detect the vibration state of the ripple voltage.

[0006] The present disclosure provides a control device, an electric compressor, and a method and program for detecting ripple voltage that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The control device disclosed herein includes an acquisition unit that samples voltage values ​​of an input voltage of a battery-powered electric compressor at irregular intervals, and a waveform calculation unit that assumes a sine wave as the waveform of a ripple component of the input voltage and calculates the waveform by fitting the sine wave so that the values ​​of the sine wave at times corresponding to the unevenly sampled voltage values ​​approximate the voltage values ​​at each of the times.

[0008] The electric compressor of the present disclosure includes the above-described control device.

[0009] In addition, in the ripple voltage detection method disclosed herein, the voltage values ​​of the input voltage of a battery-powered electric compressor are sampled at irregular intervals, a sine wave is assumed as the waveform of the ripple component of the input voltage, and the waveform is calculated by fitting the sine wave so that the values ​​of the sine wave at times corresponding to the unevenly sampled voltage values ​​approximate the voltage values ​​at each of the times.

[0010] In addition, the program disclosed herein causes a computer to execute a process of calculating the waveform by sampling voltage values ​​of an input voltage to an electric compressor driven by a battery at irregular intervals, assuming a sine wave as the waveform of the ripple component of the input voltage, and fitting the sine wave so that the values ​​of the sine wave at times corresponding to the unevenly sampled voltage values ​​approximate the voltage values ​​at each of the times. Effect of the Invention

[0011] According to the above-described control device, electric compressor, and ripple voltage detection method and program, an abnormality in the ripple voltage can be reliably detected. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of an electric compressor according to an embodiment. [Diagram 2]5A and 5B are diagrams illustrating a detection process of a ripple voltage in one embodiment. [Diagram 3] FIG. 4 is a diagram illustrating an example of resonance protection control in one embodiment. [Figure 4] 10 is a flowchart illustrating an example of control according to an embodiment. [Diagram 5] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Embodiment> Hereinafter, an electric compressor according to one embodiment will be described with reference to FIGS. 1 to 5. FIG. (composition) 1 shows an example of a schematic configuration of an electric compressor 20 provided in a vehicle air conditioner 30. The battery 1, the vehicle air conditioner 30, a vehicle device 40, and an electric circuit for driving these are mounted on a vehicle. Inductors 5a and 5b represent inductor components of the electric circuit including the battery 1, the vehicle air conditioner 30, and the vehicle device 40. The battery 1 is a power supply unit mounted on the vehicle (outside the vehicle air conditioner 30). The battery 1 supplies high-voltage DC power to the vehicle air conditioner 30 and the vehicle equipment 40. The vehicle equipment 40 includes a capacitor 2, an inverter 3, and a load 4 connected to the inverter 3. In the vehicle equipment 40, the inverter 3 converts the high-voltage DC power supplied from the battery 1 into three-phase AC power and supplies it to the load 4. If the carrier frequency of the inverter 3 is f1, a ripple voltage (described later) of frequency f1 generated by the vehicle equipment 40 may occur in the electric circuit.

[0014] The vehicle air conditioner 30 includes an electric compressor 20. The electric compressor 20 is an inverter-integrated electric compressor in which an inverter 7 is integrally built. The electric compressor 20 includes a power supply circuit 8 including a capacitor 6 and an inverter 7, a motor 9, a control device 10, a voltmeter 11, and a compression unit 12. The electric compressor 20 is driven by the inverter 7 converting high-voltage DC power supplied from a battery 1 into three-phase AC power and applying it to the motor 9. The inverter 7 and the motor 9 are connected by a power line. The inverter 7 converts the DC power supplied from the battery 1 into three-phase AC power and supplies it to the motor 9. The inverter 7 is controlled by the control device 10. The control device 10 includes a microcomputer and controls the motor 9 to operate as desired via the inverter 7 based on a control signal acquired from an ECU (Electric Control Unit) (not shown) or the like. For example, the control device 10 controls the rotation speed of the motor 9. When the motor 9 is driven to rotate by an instruction from the inverter 7, the compressor 12 compresses the refrigerant and supplies the refrigerant to a refrigerant circuit (not shown) of the vehicle air conditioner 30. The inverter 7, the voltmeter 11, and the control device 10 are connected by a signal line. The voltmeter 11 measures the DC voltage input to the inverter 7 and outputs the measured voltage value to the control device 10. The voltage measured by the voltmeter 11 is called the input voltage. The input voltage measured by the voltmeter 11 may contain a ripple component. The value obtained by subtracting the DC voltage value derived from the battery 1 from the voltage value measured by the voltmeter 11 is called the ripple voltage. If the carrier frequency of the inverter 7 is f0, a ripple voltage of frequency f0 generated by the electric compressor 20 may be generated in the electric circuit. When the ripple voltage of frequency f0 or f1 becomes large, resonance occurs in the resonant circuit formed by the capacitors 2 and 6 and the inductors 5a and 5b, and an excessive current flows in the electric circuit of FIG. 1. Therefore, the control device 10 monitors the fluctuation of the voltage value measured by the voltmeter 11, and when the ripple voltage value W becomes equal to or exceeds a predetermined threshold value α, it determines that the ripple voltage is abnormal, and performs resonance protection control to stop or decelerate the motor 9 and suppress the ripple voltage value W. This suppresses the ripple voltage generated by the electric compressor 20.

[0015] The control device 10 includes an acquisition unit 101 , a waveform calculation unit 102 , a determination unit 103 , and a control unit 104 . The acquisition unit 101 samples the voltage value measured by the voltmeter 11 at irregular intervals. The waveform calculation unit 102 calculates a waveform from the voltage values ​​sampled at irregular intervals by the acquisition unit 101. The waveform calculated by the waveform calculation unit 102 is a ripple component of the input voltage, that is, a ripple voltage. The ripple voltage may include a voltage generated by the electric compressor 20 (inverter 7) as well as a voltage generated by the vehicle device 40 (inverter 3).

[0016] Based on the waveform calculated by the waveform calculation unit 102, the determination unit 103 calculates the difference between the maximum and minimum voltage values ​​in a predetermined short time. This value is called the ripple voltage value W. The determination unit 103 compares the ripple voltage value W with a predetermined threshold value α. If the ripple voltage value W is equal to or greater than the threshold value α, the determination unit 103 decides to perform resonance protection control to protect the circuit from resonance. The resonance protection control is a control that reduces the rotation speed of the motor 9 to suppress the ripple voltage value W to less than the threshold value.

[0017] The control unit 104 instructs the inverter 7 on the rotation speed of the motor 9. When the judgment unit 103 decides to perform resonance protection control, the control unit 104 stops the motor 9. Alternatively, the control unit 104 reduces the rotation speed of the motor 9 to a predetermined rotation speed X (rpm). By stopping the motor 9 or reducing the rotation speed, the value W of the ripple voltage generated by the electric compressor 20 can be reduced.

[0018] (Ripple voltage detection process) FIG. 2 is a diagram illustrating a process for detecting a ripple voltage in one embodiment. The vertical axis of FIG. 2 is the input voltage, and the horizontal axis is the time. The diamond-shaped points plotted in FIG. 2 are the voltage values ​​of the input voltage sampled by the acquisition unit 101 at irregular intervals. The points P1 to P11 are the voltage values ​​sampled continuously in a unit time Tp (time width T1), and the points Q1 to Q11 are the voltage values ​​sampled continuously in another unit time Tq (time width T1). The waveform calculation unit 102 calculates the waveform of the ripple voltage based on the voltage values ​​sampled continuously during the time width T1. Taking the points P1 to P11 as an example, the waveform calculation unit 102 assumes a certain sine wave (for example, y=a+b×sin(c)) and performs fitting by adjusting parameters a to c of the equation of the assumed sine wave so that the values ​​of the assumed sine wave at the times corresponding to the points P1 to P11 respectively approximate the voltage values ​​of the points P1 to P11. Once an approximate sine wave has been calculated, waveform calculation unit 102 sets the sine wave as the waveform of the ripple voltage at time Tp. Waveform C1 is the waveform of the ripple voltage calculated by waveform calculation unit 102 based on points P1 to P11. Similarly, waveform C2 is the waveform of the ripple voltage at time Tq calculated by waveform calculation unit 102 based on points Q1 to Q11. Wp is the value Wp of the ripple voltage indicated by waveform C1, and Wq is the value Wq of the ripple voltage indicated by waveform C2.

[0019] Here, it is assumed that the voltage value measured by the voltmeter 11 is sampled at a constant interval T0. And the values ​​are all 0 as shown by points R1 to R11. In such a case, it seems that the amplitude of the ripple voltage is always 0 from the measured voltage value. However, in reality, a ripple voltage like the waveform C1 or C2 may be generated. If the ripple voltage shown in the waveform C2 is generated and the value W of the ripple voltage exceeds the threshold value α, resonance occurs in the electric circuit of FIG. 1. If the input voltage is sampled at equal intervals in this way, for example, when the sampling interval of the input voltage and the period of the sine wave coincide with each other, there is a possibility that the vibration state of the ripple voltage cannot be observed. Therefore, in this embodiment, the acquisition unit 101 samples the input voltage at unequal intervals, and the waveform calculation unit 102 calculates the waveform based on those values. In this way, even if a ripple voltage of any frequency is generated, it is difficult to miss the vibration.

[0020] The timing for sampling the voltage value at unequal intervals in the time span T1 may be determined in advance, or may be set randomly by the acquisition unit 101 every time the time span T1 elapses. The length of the unit time T1 and the number of samples during that time are determined so that the number of samples required for waveform calculation can be obtained and no abnormal delay in detection of the ripple voltage occurs. For example, it is considered that the risk of missing detection of the ripple voltage due to the period of the ripple voltage overlapping with the sampling period can be further reduced by randomly changing the sampling interval for each unit time.

[0021] When the unit time Tp has elapsed, the waveform calculation unit 102 calculates the waveform C1 of the ripple voltage at the unit time Tp. The judgment unit 103 compares the ripple voltage value Wp of the waveform C1 with the threshold value α, and if the ripple voltage value Wp is equal to or greater than the threshold value α, judges that the resonance protection control is to be executed. Similarly, when the waveform calculation unit 102 calculates the waveform C2 for the unit time Tq, the judgment unit 103 compares the ripple voltage value Wq with the threshold value α. If the ripple voltage value Wq is equal to or greater than the threshold value α, the judgment unit 103 judges that the resonance protection control is to be executed. In this way, the control device 10 samples the input voltage at irregular intervals for each unit time Tp, calculates the waveform of the ripple voltage during this period, and monitors the behavior of the ripple voltage. If an abnormality is found in the ripple voltage value W, the control device 10 continues to monitor the ripple voltage and performs the resonance protection control. Next, the resonance protection control will be described with reference to FIG. 3.

[0022] FIG. 3 is a diagram illustrating an example of the resonance protection control in one embodiment. The vertical axis in the upper diagram of Fig. 3 represents the value W of the ripple voltage generated by electric compressor 20, and the horizontal axis represents time. The vertical axis in the lower diagram of Fig. 3 represents the rotation speed of motor 9, and the horizontal axis represents time. The same positions on the horizontal axis in the upper diagram and the lower diagram of Fig. 3 represent the same time.

[0023] Referring to the upper diagram of Fig. 3, the value W of the ripple voltage at time t0 is 0. Referring to the lower diagram of Fig. 3, the rotation speed of the motor 9 at time t0 is Y (rpm). Y (rpm) is the required rotation speed determined by the vehicle's ECU based on the heating and cooling temperature settings set by the user.

[0024] At time t1, the value W of the ripple voltage is equal to or greater than the threshold value α. When the value W is equal to or greater than the threshold value α, the judgment unit 103 instructs the control unit 104 to execute resonance protection control. The control unit 104 then instructs the inverter 7 to set the rotation speed to 0 (zero). The progress of the rotation speed of the motor 9 when the motor 9 is stopped is shown in graph L1, and the progress of the value W of the ripple voltage is shown in graph A1. When the motor 9 is stopped, the value W of the ripple voltage also decreases as shown in graph A1. This makes it possible to prevent resonance from occurring.

[0025] The control unit 104 may reduce the rotation speed of the motor 9 instead of stopping the motor 9. The change in the rotation speed when the rotation speed of the motor 9 is reduced is shown in graph L2, and the change in the value W of the ripple voltage is shown in graph A2. The control unit 104 sets the target rotation speed to X (rpm), which is a value smaller than Y, and instructs the inverter 7 to the rotation speed X. Alternatively, the control unit 104 may set the rotation speeds set stepwise between the required rotation speed Y (rpm) and the rotation speed X (rpm) as the target rotation speed in sequence, and instruct the inverter 7 at predetermined time intervals to reduce the rotation speed of the motor 9 stepwise to the rotation speed X. When an instruction to reduce the rotation speed is given at time t1, the rotation speed of the motor 9 gradually decreases, and decreases to X (rpm) at time t1-1. This makes it possible to prevent the occurrence of resonance. In addition, by operating the motor 9 at the rotation speed X without stopping it in the resonance protection control, the vehicle air conditioner 30 can continue air conditioning even if it is weak, and the decrease in user comfort can be suppressed.

[0026] The abnormality of the ripple voltage may occur due to a transient phenomenon. Therefore, regardless of whether the motor 9 is stopped or the rotation speed of the motor 9 is reduced, when a predetermined time has elapsed since the value W of the ripple voltage has fallen below the threshold value α, the control unit 104 may determine that the transient cause of the abnormality of the ripple voltage may have been removed, and may perform control to increase the rotation speed of the motor 9 again toward the requested rotation speed Y requested by the vehicle air conditioner 30. This makes it possible to bring the operating state of the vehicle air conditioner 30 closer to an operating state according to the load, thereby restoring the comfort of the user. If the abnormality of the ripple voltage does not occur even if the rotation speed of the motor 9 is increased, the control unit 104 maintains the rotation speed Y (rpm) of the motor 9. If an abnormality in the ripple voltage occurs again, the control unit 104 stops the motor 9 or reduces the rotation speed of the motor 9, and when a predetermined time has elapsed since the value W of the ripple voltage has fallen below the threshold value α, the control unit 104 repeats the control of increasing the rotation speed of the motor 9 toward the required rotation speed Y until the abnormality in the ripple voltage no longer occurs or the number of times the rotation speed of the motor 9 is increased reaches a predetermined upper limit number. If an abnormality in the ripple voltage occurs no matter how many times the rotation speed is increased, the control unit 104 keeps the motor 9 stopped. This makes it possible to prevent resonance due to the ripple voltage, and to perform air conditioning by the vehicle air conditioner 30 if possible, thereby suppressing a decrease in user comfort. In addition, the control unit 104 may increase the rotation speed of the motor 9 stepwise toward the required rotation speed Y, rather than increasing the rotation speed to Y (rpm) at once. In this case, even if the control unit 104 cannot increase the rotation speed of the motor 9 to Y, it may increase the rotation speed to the maximum rotation speed at which an abnormality in the ripple voltage does not occur, and continue operation as is.

[0027] As shown in FIG. 3, when the source of the ripple voltage is the electric compressor 20, the control unit 104 can reduce the ripple voltage value W by reducing the rotation speed of the motor 9. However, when the source of the ripple voltage is the vehicle device 40, the abnormality of the ripple voltage cannot be removed by the control of the control device 10. For example, if the value W is equal to or greater than the threshold value α even when the rotation speed of the motor 9 is reduced, there is a possibility that the source of the ripple voltage is the vehicle device 40. When the source of the ripple voltage is the vehicle device 40, the control device 10 may wait until the value W of the ripple voltage becomes less than the threshold value α while stopping the motor 9. In addition, the control device 10 may record a log describing the occurrence of an abnormality in the ripple voltage generated by the vehicle device 40 in a storage unit (not shown). For example, the log can be provided to the manufacturer of the vehicle device 40 to request that the generation of the abnormal ripple voltage be suppressed.

[0028] Next, a flow of the ripple voltage detection process and the resonance protection control in this embodiment will be described below. Fig. 4 is a flowchart showing an example of the control in one embodiment. In the electric compressor 20, the motor 9 is driven at a required rotation speed Y according to the air conditioning load of the vehicle air conditioner 30. The acquisition unit 101 samples the latest voltage value measured by the voltmeter 11 at irregular intervals (step S10). The acquisition unit 101 outputs the sampled voltage value to the waveform calculation unit 102. The waveform calculation unit 102 calculates the waveform of the ripple voltage in a predetermined unit time (time width T1) (step S11). For example, the waveform calculation unit 102 performs sine wave fitting on the multiple voltage values ​​acquired by the acquisition unit 101 at irregular intervals within the unit time to calculate the waveform of the ripple voltage. The waveform calculation unit 102 calculates a ripple voltage value W (for example, Wp, Wq in FIG. 2) for the calculated waveform. The waveform calculation unit 102 outputs the ripple voltage value W to the determination unit 103. The determination unit 103 compares the ripple voltage value W with a threshold value α (step S12). If the value W is less than the threshold value α (step S12; No), the determination unit 103 determines that the possibility of resonance due to the ripple voltage is low, and repeats the process from step S10.

[0029] When the value W of the ripple voltage is equal to or greater than the threshold value α (step S12; Yes), the judgment unit 103 judges that there is a possibility that resonance due to the ripple voltage will occur, and instructs the control unit 104 to start resonance protection control. The control unit 104 stops the motor 9 or reduces the rotation speed of the motor 9 to a predetermined rotation speed X (rpm) (step S13). Even after the motor 9 is stopped or the like, the process from step S10 is repeated. When the resonance protection control is performed, for example, the rotation speed of the motor 9 may be increased again after a predetermined time has elapsed since the value W of the ripple voltage has fallen below the threshold value α. Furthermore, if the value W of the ripple voltage remains equal to or greater than the threshold value α even after the resonance protection control is performed, it is considered that there is an abnormality in the ripple voltage originating from the vehicle device 40. In such a case, the occurrence of the abnormality in the ripple voltage may be recorded in a log, or an alarm may be notified to the vehicle device 40.

[0030] According to this embodiment, the input voltage value of the electric compressor 20 is sampled at irregular intervals, and the waveform of the ripple voltage is calculated based on the sampling results. This makes it possible to detect any vibration of any frequency of the ripple voltage generated, and to grasp the vibration state of the ripple voltage. In addition, by detecting without fail that the ripple voltage value W is equal to or greater than the threshold value α and executing the resonance protection control, it is possible to prevent resonance and damage to the electric compressor 20, etc.

[0031] FIG. 5 is a diagram illustrating an example of a hardware configuration of a control device according to an embodiment. The computer 900 includes a CPU 901 , a main memory device 902 , an auxiliary memory device 903 , an input / output interface 904 , and a communication interface 905 . The above-mentioned control device 10 is implemented in a computer 900. The above-mentioned functions are stored in the auxiliary storage device 903 in the form of a program. The CPU 901 reads the program from the auxiliary storage device 903, loads it in the main storage device 902, and executes the above-mentioned processing in accordance with the program. The CPU 901 also reserves a storage area in the main storage device 902 in accordance with the program. The CPU 901 also reserves a storage area in the auxiliary storage device 903 for storing data being processed in accordance with the program.

[0032] In addition, a program for realizing all or part of the functions of the control device 10 may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. In addition, if a WWW system is used, the term "computer system" also includes a homepage providing environment (or display environment). In addition, the term "computer-readable recording medium" refers to a portable medium such as a CD, DVD, or USB, and a storage device such as a hard disk built into a computer system. In addition, if the program is distributed to the computer 900 via a communication line, the computer 900 that receives the program may deploy the program in the main storage device 902 and execute the above processing. In addition, the above program may be for realizing part of the above-mentioned functions, and may further be capable of realizing the above-mentioned functions in combination with a program already recorded in the computer system.

[0033] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention.

[0034] <Additional Notes> The control device 10, the electric compressor 20, and the method and program for detecting a ripple voltage described in each embodiment can be understood, for example, as follows.

[0035] (1) The control device 10 according to the first aspect includes an acquisition unit 101 that samples the voltage values ​​of the input voltage to the electric compressor 20 driven by the battery 1 at irregular intervals, and a waveform calculation unit 102 that calculates the waveform of the ripple component of the input voltage based on the voltage values ​​sampled at irregular intervals.

[0036] The control device 10 can detect the vibration state of the ripple voltage regardless of the frequency of the ripple voltage. This makes it possible to detect any abnormality in the ripple voltage without fail and to prevent the occurrence of resonance due to the abnormality in the ripple voltage.

[0037] (2) A control device 10 according to a second aspect is the control device 10 of (1), wherein the acquisition unit 101 performs the sampling at a plurality of time points (points P1 to P11, points Q1 to Q11) that are determined to divide a predetermined unit time (Tp, Tq) at unequal intervals, and the waveform calculation unit 102 calculates the waveform for each unit time. The time required to obtain the number of voltage value samples required to calculate the waveform is defined as a unit time, and by defining the time so that voltage values ​​can be sampled at irregular intervals within that unit time, it is possible to achieve complete ripple voltage detection.

[0038] (3) A control device 10 according to a third aspect is the control device 10 of (1), wherein the acquisition unit 101 determines a plurality of time points that divide a predetermined unit time (Tp, Tq) at unequal intervals and performs the sampling for each of the time points (points P1 to P11, points Q1 to Q11), and the waveform calculation unit 102 calculates the waveform for each of the unit times. By varying the sampling interval, it is possible to reduce the risk of missing a ripple voltage detection due to the period of the ripple voltage overlapping with the sampling period.

[0039] (4) The control device 10 according to a fourth aspect is the control device 10 of (1) to (3), and further includes a judgment unit 103 that judges whether a ripple voltage value W indicated by the waveform is equal to or greater than a predetermined threshold value α, and a control unit 104 that reduces the rotation speed of the motor 9 of the electric compressor 20 when the ripple voltage value W is equal to or greater than the threshold value α. When an abnormal ripple voltage is detected, the rotation speed of the motor 9 is reduced (including stopped), thereby making it possible to avoid the occurrence of resonance.

[0040] (5) An electric compressor 20 according to a fifth aspect includes the control device 10 of (1) to (4).

[0041] (6) A method for detecting ripple voltage according to a sixth aspect samples, at irregular intervals, the voltage values ​​of an input voltage to an electric compressor 20 driven by a battery 1, and calculates the waveform of the ripple component of the input voltage based on the voltage values ​​sampled at irregular intervals.

[0042] (7) A program according to a seventh aspect causes a computer to function as a means for sampling, at irregular intervals, voltage values ​​of an input voltage to an electric compressor driven by a battery, and a means for calculating a waveform of a ripple component of the input voltage based on the voltage values ​​sampled at irregular intervals. [Explanation of symbols]

[0043] 1. Battery 2. Capacitor 3. Inverter 4. Load 5a, 5b... Inductor 6. Capacitor 7. Inverter 8...Power supply circuit 9. Motor 10. Control device 101...Acquisition section 102...Waveform calculation section 103... Judgment section 104...Control section 11. Voltmeter 12. Compression section 13...Storage device 20. Electric compressor 30 Vehicle air conditioner 40 Vehicle equipment 900...Computer 901···CPU 902...Main memory 903...Auxiliary storage device 904 Input / Output Interface 905 Communication Interface

Claims

1. an acquisition unit that samples a voltage value of an input voltage of the battery-driven electric compressor at irregular intervals; a waveform calculation unit that calculates the waveform by assuming a sine wave as a waveform of a ripple component of the input voltage and fitting the sine wave so that values ​​of the sine wave at times corresponding to the voltage values ​​sampled at the uneven intervals approximate the voltage values ​​at each of the times; A control device comprising:

2. the waveform calculation unit calculates the waveform by adjusting a, b, and c so that the value of y in an equation y=a+b×sin(c) expressing the sine wave at the time t corresponding to the sampled voltage value approximates the sampled voltage value at the time t; The control device according to claim 1 .

3. the acquiring unit randomly sets a plurality of time points that divide a predetermined unit time at unequal intervals, and performs the sampling for each of the time points; The waveform calculation unit calculates the waveform for each unit time. The control device according to claim 1 .

4. a determination unit that determines whether a ripple voltage value indicated by the waveform is equal to or greater than a predetermined threshold value; a control unit that reduces a rotation speed of a motor of the electric compressor when a value of the ripple voltage is equal to or greater than the threshold value; The control device according to claim 1 , further comprising:

5. An electric compressor comprising the control device according to any one of claims 1 to 4.

6. The voltage value of the input voltage of the battery-driven electric compressor is sampled at irregular intervals; a sine wave is assumed as the waveform of the ripple component of the input voltage, and the waveform is calculated by fitting the sine wave so that values ​​of the sine wave at times corresponding to the voltage values ​​sampled at the uneven intervals approximate the voltage values ​​at each of the times; How to detect ripple voltage.

7. On the computer, The voltage value of the input voltage of the battery-driven electric compressor is sampled at irregular intervals; a process of calculating the waveform by assuming a sine wave as the waveform of the ripple component of the input voltage and fitting the sine wave so that the values ​​of the sine wave at times corresponding to the voltage values ​​sampled at the uneven intervals approximate the voltage values ​​at each of the times; A program that executes the following.

Images