JP5381229B2 - Capacitor deterioration detection circuit and electronic device equipped with the same - Google Patents

Description

  The present invention relates to a voltage doubler rectifier circuit including a voltage doubler capacitor and a smoothing capacitor, and a capacitor deterioration detecting a deterioration of the voltage doubler capacitor and / or the smoothing capacitor when a capacity reduction occurs due to the capacitor deterioration due to long-term use. The present invention relates to a detection circuit and an electronic apparatus including the detection circuit.

In a voltage doubler rectifier circuit used for an inverter circuit or the like, a voltage doubler capacitor for boosting a DC voltage and a smoothing capacitor for smoothing a ripple are used. Since these capacitors are long-lived components, capacitor components are selected on the assumption of the usage conditions of the product such as operating voltage and operating temperature. However, performance degradation such as capacity reduction occurs with use of capacitors, and in the worst case, explosion-proof valves of voltage doubler capacitors and / or smoothing capacitors may rupture, which may cause destruction of the board on which these capacitors are mounted. is there.
Such danger must be avoided in advance, and safety must be ensured until the product is discarded.

Therefore, in the prior art, a deterioration detection circuit for detecting the life of the smoothing capacitor in advance has been proposed (Patent Document 1).
In FIG. 8 showing this prior art, after the AC power supply 11 is rectified by the rectifier 12 and smoothed by the smoothing capacitor 13, the load current detected by the load current detector 15 is also detected by the ripple voltage detector 14. The DC voltage across the smoothing capacitor 13 is sent to the control unit 19. The control unit 19 calculates a ripple voltage value and compares it with a preset predetermined ripple value for warning. If the ripple voltage value is exceeded, a signal that limits the load current, such as reducing the rotational speed of the three-phase motor 17. Is sent to the conversion unit 16 via the motor drive unit 18 to perform protection control. Further, when the calculated ripple voltage value is compared with a predetermined ripple value for abnormality determination that is set in advance and stored in the storage unit 20 and is determined to be abnormal, a signal for abnormally stopping the system is sent via the motor drive unit 18. Send protection control to the conversion unit 16. In addition, a ripple voltage for warning / abnormality determination corresponding to the load current is set as a factor for determining an abnormality, and protection control corresponding to the detected load current is performed.

JP2007-240450A.

Various inventions for detecting deterioration in a circuit having only a smoothing capacitor have been proposed.
However, in the past, even in a voltage doubler rectifier circuit equipped with a voltage doubler capacitor and a smoothing capacitor, regardless of the capacitor's lifetime, the factor for determining an abnormality is common, and the specified value and protection control in the event of abnormality are also common Therefore, the difference that appears at the time of abnormality was not considered between when the smoothing capacitor deteriorated and when the voltage doubler capacitor deteriorated.

The present invention provides a capacitor degradation detection circuit capable of detecting degradation of these two types of capacitors in a voltage doubler rectifier circuit including a voltage doubler capacitor and a smoothing capacitor, and an electronic device including the same. With the goal.
In addition, the present invention provides a capacitor deterioration detection circuit that can detect whether the capacitor having a simple detection control and the deteriorated capacitor is a voltage doubler capacitor or a smoothing capacitor, and detects the deterioration of the capacitor in more detail. It aims at realizing the electronic device provided with.

As a result of experiments and research, the present inventors have found that there are the following differences between the deterioration characteristics of the smoothing capacitor and the deterioration characteristics of the voltage doubler capacitor in the voltage doubler rectifier circuit including the voltage doubler capacitor and the smoothing capacitor. .
When the voltage doubler capacitor deteriorates due to use and the capacity is reduced, the charge amount of the voltage doubler capacitor is reduced. At this time, when the load is connected, the discharge amount is larger than the charge amount, so that the discharge is faster than the charge and a voltage drop occurs across the voltage doubler capacitor. Since the input current flows due to the voltage difference between the input voltage and the voltage across the voltage doubler capacitor, the phase of the input current peak advances as the voltage drop occurs (the input current flows faster than the power supply voltage increases), and the power factor Becomes worse. However, since it is smoothed by a normal smoothing capacitor, the influence as a ripple voltage is small.
On the other hand, when the smoothing capacitor is deteriorated by use and the capacity is reduced, if the voltage doubler capacitor is normal, the charge amount is sufficient and charging / discharging is performed in a well-balanced manner. At this time, even if a load is connected, charging and discharging are performed in a well-balanced manner, so there is no excessive discharge for charging and no voltage drop occurs. Therefore, since no voltage drop occurs, the phase of the input current peak does not change. However, the smoothing capacitor is difficult to be charged due to a decrease in capacitance, and the DC voltage including ripple is not smoothed, and the influence as ripple increases.
The present invention has been made based on the above findings, and is characterized by having the following configuration.

(1) The present invention provides a voltage doubler rectifier circuit having a voltage doubler capacitor and a smoothing capacitor, comprising a voltage detection unit for detecting a DC voltage across the smoothing capacitor, an input current detection unit for detecting an input current, and a control unit Calculates a ripple voltage value and an average voltage value from the DC voltage, and calculates an input current peak phase and a reference input current peak phase from the input current.
The deterioration of the smoothing capacitor is determined by comparing the ripple voltage value with the comparison ripple voltage value stored in the storage unit, and comparing the average voltage with the comparison average voltage stored in the storage unit.
The degradation of the voltage doubler capacitor is caused by the phase difference between the input current peak value and the reference input current peak value stored in the storage unit, and the phase difference between the comparison input current peak phase stored in the storage unit and the reference input current peak phase (comparison input current level). (Phase difference), and the comparison is made by comparing the average voltage with the comparison average voltage stored in the storage unit.
In addition, the control unit detects the drive rotation speed of a motor connected as a load and stores it in the storage unit.

(2) The comparison ripple voltage value in the item (1) indicates a warning ripple voltage value indicating that the deterioration degree of the smoothing capacitor is a characteristic requiring attention, and a characteristic in which the deterioration degree is determined to be a failure. It is composed of abnormal ripple voltage values.

(3) The comparison average voltage value in the item (1) is a warning average voltage value indicating that the deterioration degree of the smoothing capacitor and the voltage doubler capacitor is a characteristic that requires attention, and a characteristic in which the deterioration degree is determined to be a failure. It is constituted by an abnormal average voltage value indicating that there is.

(4) The reference input current peak phase of the item (1) is a value when the voltage doubler capacitor is normal, and consists of several patterns depending on the drive rotation speed pattern and input current pattern of the motor connected as a load. These patterns are stored in the storage unit in association with the values detected in (1) above.

(5) The comparison input current peak phase in the item (1) is a warning input current peak phase indicating that the deterioration degree of the voltage doubler capacitor is a characteristic that requires attention, and a characteristic in which the deterioration degree is determined to be a failure. And an abnormal input current peak phase.

According to the first aspect of the present invention, the input current of the voltage doubler rectifier circuit is detected in the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier unit with the voltage doubler capacitor, smoothes it with the smoothing capacitor, and supplies the load to the load. The phase difference between the phase of the input current peak when the voltage doubler capacitor is normal and the phase of the input current peak when determining the deterioration of the voltage doubler capacitor from the input current detected by the input current detector. An input current peak phase calculation unit for calculating the input current peak phase difference, and determining deterioration of the voltage doubler capacitor based on a difference between the phase difference and a preset comparison input current peak phase difference. Therefore, unlike the phenomenon that appears when the smoothing capacitor deteriorates, the deterioration is caused by the phase shift (phase difference) of the input current peak that appears when the voltage doubler capacitor deteriorates. It detects, it is possible to detect which capacitor has degraded.

According to a second aspect of the present invention, the input current peak phase calculation unit measures an input current value at predetermined time intervals for at least a power supply cycle, sets the maximum value among them as an input current peak, and is generated for each power supply cycle. Since the phase from the interrupt to the input current peak is calculated as the phase of the input current peak, the input current peak phase shift (phase difference) that appears when the voltage doubler capacitor deteriorates can be accurately detected Can do.

According to the third aspect of the present invention, the input current of the voltage doubler rectifier circuit is detected in the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier unit with the voltage doubler capacitor, smoothes it with the smoothing capacitor, and supplies the load to the load. An input current detection unit, a voltage detection unit for detecting a voltage at both ends of the smoothing capacitor, a phase of the input voltage peak when the voltage doubler capacitor is normal from the input current detected by the input current detection unit, and the voltage doubler An input current peak phase calculation unit for calculating an input current peak phase difference that is a phase difference from an input current peak phase at the time of capacitor deterioration determination, and a ripple voltage from a voltage at both ends of the smoothing capacitor detected by the voltage detection unit And a ripple voltage calculator for calculating the voltage doubler voltage based on a difference between the input current peak phase difference and a preset comparison input current peak phase difference. Since the deterioration of the smoothing capacitor is determined based on the difference between the ripple voltage and a preset comparison ripple voltage, it is possible to accurately detect the type of the deteriorated capacitor. Can do.

  According to a fourth aspect of the present invention, the input current peak phase calculation unit measures an input current value at predetermined time intervals for at least a power supply cycle, sets the maximum value among them as an input current peak, and is generated every power supply cycle. The phase from the interruption to the input current peak is calculated as the phase of the input current peak, and the ripple voltage calculation unit measures the voltage across the smoothing capacitor every predetermined time for at least the power cycle, and the maximum value Therefore, the phase shift (phase difference) of the input current peak value and the ripple voltage can be accurately detected.

According to the fifth aspect of the present invention, the input current of the voltage doubler rectifier circuit is detected in the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier unit with the voltage doubler capacitor, smoothes it with the smoothing capacitor, and supplies the load to the load. An input current detection unit, a voltage detection unit for detecting a voltage at both ends of the smoothing capacitor, a phase of the input voltage peak when the voltage doubler capacitor is normal from the input current detected by the input current detection unit, and the voltage doubler An input current peak phase calculation unit for calculating an input current peak phase difference that is a phase difference from an input current peak phase at the time of capacitor deterioration determination, and an average voltage from voltages at both ends of the smoothing capacitor detected by the voltage detection unit An average voltage calculation unit that calculates the ripple voltage calculation unit that calculates a ripple voltage from the voltage across the smoothing capacitor detected by the voltage detection unit, Degradation of the voltage doubler capacitor is determined only by the difference between the input current peak phase difference and the preset comparison input current peak phase difference, or the difference between the input current peak phase difference and the preset comparison input current peak phase difference, and A determination is made based on a combination of a difference between the average voltage and a preset comparison average voltage, and deterioration of the smoothing capacitor is determined only by a difference between the ripple voltage and a preset comparison ripple voltage, or the ripple voltage and the preset voltage. Since the discrimination is based on the difference between the set comparison ripple voltage and the difference between the average voltage and the preset comparison average voltage, deterioration of the voltage doubler capacitor is caused by a current peak phase shift (phase difference). Not only based on the average voltage, but also the smoothing capacitor deterioration is based not only on the ripple voltage value but also on the average voltage. By another, it is possible to detect the deterioration state type and a capacitor of the capacitor are degraded more accurately. In addition, since the measured ripple voltage value is compared with the predetermined comparison ripple voltage value and the measured average voltage value is compared with the predetermined comparison average voltage value to determine the deterioration of the smoothing capacitor, the smoothing capacitor is accurately measured even when the load is light. Degradation can be determined, and a degradation state that cannot be detected only by the ripple voltage can also be determined.

According to a sixth aspect of the present invention, the input current peak phase calculation unit measures an input current value at predetermined time intervals for at least a power supply cycle, sets the maximum value among them as an input current peak, and is generated for each power supply cycle. The phase from the interruption to the input current peak is calculated as the phase of the input current peak, and the average voltage calculation unit measures the voltage at both ends of the smoothing capacitor every predetermined time for at least the power cycle, and the average value thereof The ripple voltage calculation unit is configured to measure a voltage at both ends of the smoothing capacitor every predetermined time for at least a power cycle and detect a difference between the maximum value and the minimum value as a ripple voltage. Therefore, it is possible to accurately detect the phase shift (phase difference) of the input current peak, the average input voltage, and the ripple voltage.

According to the seventh aspect of the present invention, the input current peak phase difference determination level is the comparison input current peak phase setting unit, and the ripple voltage determination level is the comparison ripple voltage value setting unit, and the average voltage determination level is Is set to a warning value indicating that the degree of deterioration is determined to require attention and an abnormal value indicating that the degree of deterioration is determined to be a failure in the comparative average voltage value setting unit. The deterioration state can be classified into three states, normal, warning, and abnormal, and appropriate processing can be performed according to each state.

According to the eighth aspect of the present invention, the deterioration detection circuit of the capacitor of the present invention is mounted in, for example, an outdoor unit of an air conditioner, so that the deterioration of the smoothing capacitor and the voltage doubler capacitor can be accurately detected even when the load fluctuation is severe. In addition, the operation of the air conditioner can be restricted according to the degree of deterioration, and a safe operation can be performed by preventing a failure due to deterioration of the capacitor.

It is an electric circuit diagram showing an embodiment of a capacitor deterioration detection circuit according to the present invention. 6 is a flowchart for explaining the operation of the capacitor deterioration detection circuit according to the present invention. The characteristics of the smoothing capacitor when it is normal and deteriorated are shown. (A) is a ripple voltage characteristic chart, (b) is an average voltage characteristic chart, and (c) is an input current peak phase characteristic chart. is there. FIG. 6A shows changes over time in the capacitance of a capacitor. FIG. 5A is a characteristic diagram of a conventional capacitor deterioration detection circuit, and FIG. 5B is a characteristic diagram of a capacitor deterioration detection circuit of the present invention. (A) is a characteristic diagram of the aging of the ripple voltage when the smoothing capacitor ruptures, (b) is a characteristic diagram of the aging of the average voltage, and (c) is the aging of the input current peak phase shift when the voltage doubler capacitor is ruptured. It is a characteristic view of a change. It is a characteristic figure of the motor rotation speed at the time of warning processing. It is an electric circuit diagram which shows the other Example of the deterioration detection circuit of the capacitor | condenser of this invention. It is an electric circuit diagram of a conventional capacitor deterioration detection circuit.

  The capacitor deterioration detection circuit according to the present invention detects the input current of the voltage doubler rectifier circuit to the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier unit with a voltage doubler capacitor, smoothes it with a smoothing capacitor, and supplies it to the load. And an input current that is a phase difference between the phase of the input current peak when the capacitor is normal and the phase of the input current peak when determining deterioration of the capacitor from the input current detected by the input current detection unit An input current peak phase calculation unit that calculates a peak phase difference is provided, and deterioration of the voltage doubler capacitor is determined based on a difference between the phase difference and a preset comparison input current peak phase difference.

Degradation of the voltage doubler capacitor is determined based on the difference between the input current peak phase difference and the preset comparison input current peak phase difference, and is determined based on the difference between the ripple voltage and the preset comparison ripple voltage. It is characterized by.

  In addition to determining the deterioration of the voltage doubler capacitor, the deterioration of the smoothing capacitor is determined based on the ripple voltage and the average voltage.

  The input current peak phase phase difference judgment level is the comparison input current peak phase setting unit, the ripple voltage judgment level is the comparison ripple voltage setting unit, and the average voltage judgment level is degraded by the comparison average voltage setting unit. A warning value indicating that the degree is determined to require attention and an abnormal value indicating that the degree of deterioration is determined to be a failure are set.

A capacitor deterioration detection circuit according to a first embodiment of the present invention will be described with reference to FIG.
A power supply circuit for driving a load (for example, a three-phase motor) 28 includes a rectifying unit 22 of an AC power supply 21, a voltage doubler capacitor 23 including two boosting capacitors 23 a and 23 b connected in series, and a smoothing capacitor for smoothing ripples 24, a voltage doubler rectifier circuit, an input current detector 25 having a coil 25a and a resistor 25b, a voltage detector 26 having two resistors 26a and 26b, and three transistors 6a to 27f. A phase AC converter 27 (inverter), an inverter drive circuit 29 that drives the converter 27, a motor rotation speed detection circuit 30, and a controller 31 that controls the inverter drive circuit 29. ing.

A capacitor deterioration detecting unit (capacitor deterioration detecting circuit) according to the present invention is connected to the voltage doubler rectifier circuit portion of the power supply circuit. The capacitor deterioration detection unit is mainly composed of the control unit 31.
The control unit 31 is mainly configured by a CPU unit (not shown) that controls the entire control unit 31, a calculation unit, and a data storage unit 35.

The calculation unit performs various calculations, settings, discrimination, and the like under the control of the CPU. The input current A / D conversion unit 32, the motor rotation number A / D conversion unit 33, the input voltage A / D D converter 34, input current measuring unit 36, input current peak phase calculating unit 37, voltage measuring unit 39, ripple voltage calculating unit 40, average voltage calculating unit 41, comparative ripple voltage setting unit 42, comparative average voltage setting unit 43, A comparison input current peak phase setting unit 44, a smoothing capacitor deterioration determining unit 45, a voltage doubler capacitor deterioration determining unit 46, a motor rotation speed control unit 47, a warning display control unit 48, a system stop control unit 49, and an inverter control unit 50 It has.
The inverter control unit 50 controls the inverter drive circuit 29.
The input current peak phase calculation unit 37, the voltage measurement unit 39, the ripple voltage calculation unit 40, and the average voltage calculation unit 41 calculate an initial value (reference value) immediately after the start of operation and a value based on data that changes with time, respectively. .
An input circuit 52 is connected to the comparison ripple voltage setting unit 42, the comparison average voltage setting unit 43, and the comparison input current peak phase setting unit 44, and a warning value and an abnormal value are set, respectively.
A display unit 51 is connected to the warning display control unit 48.

This will be described in more detail. In the following explanation,
The ripple voltage Er is a measured value Erx, a reference value Er0, a warning value Er1, and an abnormal value Er2.
The input average voltage Ea is measured value Eax, reference value Ea0, warning value Ea1, abnormal value Ea2,
Input current I is measured value Ix, reference value I0, warning value I1, abnormal value I2,
The input current peak phase θ is a measured value θx, a reference value θ0, a warning value θ1, and an abnormal value θ2.

(1) The DC voltage detection signal from the voltage detection unit 26 is A / D converted by the A / D conversion unit 34 and sent to the voltage measurement unit 39. At this voltage measurement unit 39, for example, at least every 1 msec. The DC voltage is measured during the power cycle, for example, 100 msec. The data is stored in the storage unit 35.
The ripple voltage calculation unit 40 searches for the maximum value and the minimum value from the measurement results for 100 msec stored in the storage unit 35, and calculates the ripple voltage Er shown in FIG. The data is stored in the storage unit 35. The detection of the ripple voltage Er is continuously performed at a predetermined time interval from the start of operation.
Further, the ripple voltage calculation unit 40 has a power supply frequency measured every 1 msec measured by the DC voltage measurement unit 39 when the capacitor immediately after the start of operation (for example, immediately after the AC power supply 21 is first applied to the power supply circuit) is in a normal state (initial state). Based on the input voltage during the period, the reference ripple voltage Er0 shown in FIG. The data is stored in the storage unit 35.

(2) The average voltage calculation unit 41 performs measurement based on the measurement result of the DC voltage for, for example, 100 msec stored in the storage unit 35, measured by the voltage measurement unit 39, and the result shown in FIG. An average voltage value Eax of the input DC voltage shown is calculated. The average voltage value Eax is calculated continuously at a predetermined time interval from the start of operation.
Further, the average voltage calculation unit 41 has a power supply frequency measured every 1 msec measured by the DC voltage measurement unit 39 when the capacitor immediately after the start of operation (for example, immediately after the AC power supply 21 is first applied to the power supply circuit) is in a normal state (initial state). A reference average voltage value Ea0 is calculated based on the input voltage of the period. The data is stored in the storage unit 35.
(3) The rotation speed detection circuit 30 continuously detects the rotation speed of the motor 28 from the start of operation, A / D-converts the data by the A / D conversion unit 33, and stores the data in the storage unit 35.

(4) A DC current detection signal from the input current detection unit 25 is A / D converted by the A / D conversion unit 32 and sent to the input current measurement unit 36. The input current measurement unit 36, for example, 1 msec. Measure the input current at least during each power cycle. The data is stored in the storage unit 35.
The input current peak phase calculation unit 37 searches for the maximum value Ix shown in FIG. 3C from the stored measurement results during the power cycle, and uses this as the input current peak value (Ix includes phase information θx). May be.) The data is stored in the storage unit 35. The detection of the input current peak value Ix is continuously performed at a predetermined time interval from the start of operation.
(5) The input current peak phase calculation unit 37 is measured by the input current measurement unit 36 when the capacitor immediately after the start of operation (for example, immediately after the AC power supply 21 is first applied to the power supply circuit) is in a normal state (initial state). A reference input current peak value I0 shown in FIG. 3C is calculated based on the input current during the power supply cycle every 1 msec (I0 may include phase information θ0). The data is stored in the storage unit 35.
(6) Further, the input current peak calculation unit 37, in the above (4) and (5), the power supply cycle of the input current peak value Ix and the reference input current peak value I0 that change over time as shown in FIG. The input current peak phase θx and the reference input current peak phase θ0 are calculated as the time from the power interruption that occurs every time, and the input current peak phase difference θ = θ0−θx is calculated. The phases θ0 and θx and the phase difference θ of these input current peak values are stored in the storage unit 35. Further, the rotational speed of the motor 28 at that time is also detected and stored in the storage unit 35. Here, the power interruption that occurs every power cycle is a timing signal that is input to the control unit 31 by detecting the timing of the zero cross point of the AC power source (for example, the point at which the polarity of the power source changes from negative to positive).

(7) The comparison ripple voltage setting unit 42 refers to a reference ripple voltage Er0 as indicated by a solid line in FIG. 3A immediately after the start of operation calculated by the ripple voltage calculation unit 40, according to a command from the input circuit 52. For example, Er0 is multiplied by a predetermined ripple coefficient to set a warning ripple voltage Er1 (for example Er0 × 1.2) and an abnormal ripple voltage Er2 (for example Er0 × 1.5) to be compared. The warning value Er1 indicates that if a ripple voltage higher than this is detected, it is a ripple voltage that does not cause a failure immediately but may cause a failure in some cases. The abnormal value Er2 indicates that there is a possibility of failure when a ripple voltage higher than this is detected. The warning value Er1 and the abnormal value Er2, or the respective predetermined ripple coefficients may be set in the storage unit 35 in advance.

(8) The comparative average voltage setting unit 43 refers to the average voltage Ea0 as indicated by a solid line in FIG. 3B immediately after the start of operation calculated by the average voltage calculation unit 41, for example, according to a command from the input circuit 52 A warning average voltage Ea1 (for example, Ea0 × 0.9) and an abnormal average voltage Ea2 (for example, Ea0 × 0.7) are set by multiplying Ea0 by a predetermined average voltage coefficient. The warning value Ea1 indicates that when an average voltage equal to or lower than this is detected, it is an average voltage that does not cause a failure immediately but may possibly cause a failure. The abnormal value Ea2 indicates that the average voltage having a possibility of failure is detected when an average voltage lower than this is detected. The warning value Ea1 and the abnormal value Ea2 or the respective predetermined average voltage coefficients may be set in the storage unit 35 in advance.

(9) The comparison input current peak phase setting unit 44 refers to the reference input current peak phase θ0 as shown in FIG. 3C calculated by the input current peak calculation unit 37 when the capacitor is normal. For example, the warning input current peak phase θ1 (for example, θ0-20 degrees) and the abnormal input current peak phase θ2 (for example, θ0-40 degrees) are set by subtracting a predetermined phase from θ0, for example. The warning value θ1 indicates an input current peak phase that does not cause a failure immediately but may possibly fail if a further shift in the input current peak phase occurs. The abnormal value θ2 indicates that the input current peak phase has a possibility of failure when the input input current peak phase shifts further. Each predetermined phase to be subtracted from the warning value θ1 and the abnormal value θ2 or the reference value θ0 may be set in the storage unit 35 in advance.

(10) The life of the capacitor refers to a case where the capacity of the capacitor gradually decreases due to aging due to the operation of the apparatus and decreases to a predetermined ratio from the initial capacity. The predetermined comparison ripple voltage Er0, comparison average voltage Ea0, comparison input current peak phase θ1, θ2 (or respective predetermined phases subtracted from the reference input current phase) as described in (7), (8) and (9) above. Depends on the voltage applied to the capacitor and the load, and therefore is determined in consideration of the maximum load when designing a device using the capacitor. Further, since the capacitance may be reduced due to the initial variation of the capacitor itself, it is determined in consideration of the margin.

(11) The decrease in the capacitance of the smoothing capacitor 24 appears as an increase in the ripple voltage shown in FIG. 3A and a decrease in the average voltage shown in FIG. When the capacitance is large, the ripple voltage is small and the average voltage drop is also small. When the capacitance is small, the ripple voltage is large and the average voltage drop is also large.
(12) The decrease in the capacity of the voltage doubler capacitor 23 appears as a shift (phase difference) in the input current peak phase shown in FIG. When the capacity is small, the peak phase moves in the direction in which the phase advances compared to when the capacity is large. Moreover, it appears as a decrease in the average voltage shown in FIG.

(13) The measured value Erx of the ripple voltage calculated by the ripple voltage calculation unit 40 is compared with the warning value Er1 of the ripple voltage set by the comparison ripple voltage setting unit 42, and the measured value Erx is equal to or higher than the warning value Er1 or the average voltage When the measured value Eax of the average voltage calculated by the calculation unit 41 is equal to or less than the warning value Ea1 of the average voltage set by the comparison average voltage setting unit 43, the deterioration determination unit 45 of the smoothing capacitor deteriorates the smoothing capacitor 24 ( Warning). In this case, a warning process for lowering the rotation speed of the motor 28 is performed by the inverter drive section 29 and the conversion section (inverter) 27 through the motor rotation speed control section 47 and the inverter control section 50. The warning process may include a process of displaying a warning on the display unit 51 via the warning display control unit 48 at the same time.
The measured value Erx of the ripple voltage calculated by the ripple voltage calculating unit 40 is compared with the abnormal value Er2 of the ripple voltage set by the comparative ripple voltage setting unit 42, and the measured value Erx is equal to or higher than the abnormal value Er2, or the average voltage calculating unit 41 When the measured value Eax of the average voltage calculated in step S1 becomes equal to or less than the abnormal value Er2 of the average voltage, the smoothing capacitor deterioration determining unit 45 determines that the smoothing capacitor 24 is deteriorated (abnormal). In this case, the system is stopped. Abnormal processing for stopping the system is performed via the control unit 49 and the inverter control unit 50. Although not shown, a process for displaying a warning on the display unit 51 at the same time may be included.

(14) The phase difference θ between the measured value θx of the input current peak phase calculated by the input current peak phase calculation unit 37 and the reference value θ0 of the input current peak phase is the input current peak set by the comparison input current peak phase setting unit 44 The measured value of the average voltage calculated by the average voltage calculation unit 41 is equal to or greater than the phase difference (comparison input current peak phase difference) θ01 between the warning value θ1 (= θ0−20 °) and the reference value θ0 of the input current peak When Eax is equal to or lower than the warning value Ea1 (= Ea0 × 0.9) of the average voltage set by the comparison average voltage setting unit 43, it is determined that the voltage doubler capacitor 23 is deteriorated (warning). A warning process for decreasing the number of revolutions of the motor 28 through the motor revolution number control unit 47 and the inverter control unit 50 is performed. The warning process may include a process of displaying a warning on the display unit 51 via the warning display control unit 48 at the same time.
The phase difference θ between the measured value θx of the input current peak phase calculated by the input current peak phase calculation unit 37 and the reference value θ0 of the input current peak phase is an abnormality in the input current peak phase set by the comparison input current peak phase setting unit 44. A phase difference (comparison input current peak phase difference) θ02 between the value θ2 (= θ0−40 °) and the reference value θ0 of the input current peak phase, and a measured value Eax of the average voltage calculated by the average voltage calculation unit 41 Is equal to or less than the abnormal value Ea0 × 0.7 of the average voltage, the system stop control unit 49 determines that the voltage doubler capacitor is deteriorated (abnormal), and passes through the system stop control unit 49 and the inverter control unit 50. Abnormal processing to stop. Although not shown, a process for displaying a warning on the display unit 51 at the same time may be included.

The operation of the capacitor deterioration detection circuit configured as described above according to the present invention will be described with reference to the flowchart shown in FIG.
(A) Immediately after the AC power supply 21 is first applied to the power supply circuit, various initial values are calculated and stored in the storage unit 35. Specifically, the reference ripple voltage Er0, the reference input average voltage Ea0, and the reference input current phase θ0 are detected and calculated as initial values when the capacitor is in a normal state (initial state), and stored in the storage unit 35. The comparison ripple voltage setting unit 42 compares the ripple voltage (warning value Er1 / abnormal value Er2), the comparative average voltage setting unit 43 compares the average voltage (warning value Ea1 / abnormal value Ea2), and the comparison input current peak phase setting unit 44. The comparison input current peak phase (warning value θ1 / abnormal value θ2) is set and stored in the storage unit 35.

(B) The AC power supply 21 is full-wave rectified by the rectifier 22, boosted to a double voltage by the voltage doubler capacitor 23, and smoothed by the smoothing capacitor 24. This DC voltage is supplied to the conversion unit (inverter) 27, a control signal is output from the inverter control unit 50 of the control unit 31 to the inverter drive unit 29, and the conversion unit (inverter) is output by the switching signal output from the inverter drive unit 29. ) 27 transistors 27 a to 27 f are switched to be converted into a three-phase alternating current and supplied to the motor 28. It is assumed that the motor 28 has been operated for a long time.

(C) The motor 28 is continuously operated, and the detection and calculation of the ripple voltage Erx, the average voltage Eax, and the input current phase θx are repeated every predetermined time (when determining deterioration of the capacitor).
When the operation of the motor 28 is continued for a long period of time, as shown in (p1) of FIGS. 4 (a) and 4 (b), the capacity of the capacitor is reduced and the life of the inverter is approached. When the motor 28 continues to operate, the capacitor generates heat and ruptures the valve, resulting in a sudden decrease in capacity and a life span.

Even after s1 in FIG. 5C reaches the end of life and the valve ruptures, the voltage doubler capacitor 23 is not immediately destroyed. When the operation is continued as it is, the voltage of the voltage doubler capacitor 23 is abruptly decreased, and it becomes difficult to charge due to the decrease in the capacity. Since the motor 28 is connected, the amount of discharge is larger than the amount of charge, and the discharge is faster than the charge, resulting in a voltage drop across the voltage doubler capacitor 23. Since the input current flows due to the voltage difference from the input voltage, the phase (position) of the input current peak is more likely to advance as the voltage drop occurs as shown in FIG. That is, when only the voltage doubler capacitor 23 is deteriorated, the ripple voltage Er is not greatly affected, and the deviation θ of the input current peak phase θx from the normal voltage doubler capacitor θ0 becomes large. Further, the average voltage Ea is reduced as shown by s1 in FIG.
Note that, when the smoothing capacitor 24 is in a substantially normal state as shown in FIG. 5C, the smoothing capacitor 24 smoothes the surface, so that the influence on the ripple voltage is small.

The smoothing capacitor 24 does not break immediately even after the lifetime is reached at q1 in FIG. When the operation is continued as it is, the smoothing capacitor 24 rapidly decreases in capacity, and the ripple voltage Er increases due to the decrease in capacity. However, as shown by the dotted line characteristic in FIG. 5A, if the voltage doubler capacitor 23 is substantially normal, the charge amount of the voltage doubler capacitor 23 is sufficient, and charge / discharge is performed in a well-balanced manner. Even when the motor 28 is connected, charging and discharging are performed in a well-balanced manner, so there is no excessive discharge for charging and no voltage drop occurs. That is, when the smoothing capacitor 24 deteriorates, the ripple voltage Er increases or the average voltage Ea decreases as indicated by q1 in FIG.

(D) Continue operation while repeating detection and calculation of ripple voltage Erx, average voltage Eax, and input current phase θx.
(E-1) After the continuous operation, the input current peak phase calculation unit 37 calculates the input current phase θx, and the phase difference θ (= θx−θ0) between the measured value θx and the reference value θ0 already calculated in (A). ) Is calculated. Further, the phase difference θ01 (= θ1−θ0) between the warning value θ1 set by the comparison input current peak phase setting unit 44 and the reference value θ0 is calculated. Further, the average voltage calculation unit 41 calculates the average voltage Eax. Then, (θx−θ0) and (θ1−θ0) are compared to determine whether θ is equal to or greater than θ01 and whether Eax is equal to or less than the warning average voltage Ea1 set by the comparison average voltage setting unit 43. If the condition is not satisfied, NO is determined and the process proceeds to (H-2).
(E-2) After the continuous operation, the measured value Erx calculated by the ripple voltage calculating unit 40 is compared with the warning value Er1 set by the comparative ripple voltage value setting unit 42, and the measured value Erx is equal to or higher than the warning value Er1. It is determined whether the measured value Erx is equal to or less than the warning value Er1 set by the comparative average voltage value setting unit 43. When the condition is not satisfied, it becomes NO. Even if the capacity of the voltage doubler capacitor 23 and / or the smoothing capacitor 24 decreases, if both (E-1) and (E-2) are NO, the process returns to (D) and the operation of the motor 28 continues.

(F) In (E-1), whether the phase difference θ is greater than or equal to θ1 at s2 in FIG. 5C, or the average voltage Ea is less than or equal to the warning value Ea1 at r1 in FIG. 2), when the ripple voltage Er is equal to or higher than the warning value Er1 at q2 in FIG. 5A, or the average voltage Ea is equal to or lower than the warning value Ea1 at r1 in FIG. 5B, at least one of them becomes YES. Then, the inverter drive circuit 29 is controlled via the inverter control unit 50 according to a command from the motor rotation number control unit 47, and the rotation number of the motor 28 is decreased at t1 in FIG. At the same time, an abnormal message and other warnings are displayed on the display unit 51 via the warning display control unit 48.
(G) When (E-1) or (E-2) becomes YES, the rotational speed of the motor 28 is decreased and the operation of the motor 28 is continued.

(H-1) The phase difference θ (= θx−θ0) between the input current peak phase θx calculated by the input current peak phase calculation unit 37 and the reference value θ0 while continuing the operation by lowering the rotational speed of the motor 28 is obtained. The phase difference θ02 (= θ2−θ0) between the abnormal value θ2 set by the comparative input current peak phase setting unit 44 and the reference value θ0 is equal to or larger than the abnormal value Ea2 set by the comparative average voltage setting unit 43. Is determined. If the condition is not satisfied, NO is determined and the process proceeds to (H-2).
(H-2) The ripple voltage Erx calculated by the ripple voltage calculation unit 40 is equal to or higher than the abnormal value Er2 set by the comparison ripple voltage setting unit 42 or the average voltage while lowering the rotation speed of the motor 28 and continuing the operation. It is determined whether Eax is equal to or less than the abnormal value Ea2 set by the comparative average voltage setting unit 43. If the condition is not satisfied, NO is returned and the operation returns to the continuous operation (G).

(I) In (H-1), the phase difference θ is greater than or equal to θ2 at s3 in FIG. 5C, or the average voltage Eax is less than or equal to the abnormal value Ea2 at r2 in FIG. 2), when q3 in FIG. 5A, the ripple voltage Erx is equal to or higher than the abnormal value Er2, or the average voltage Eax is equal to or lower than the abnormal value Ea2 at r2 in FIG. 5B, or at least one of them is YES. In response to a command from the system stop control unit 49, the inverter drive unit 29 is controlled via the inverter control unit 50, and the power is shut off at r2 in FIG. 5B and the operation of the motor 28 is stopped at t3 in FIG. .
(J) Stops abnormally as shown by p3 in FIG. Incidentally, in the past, there was a risk that the apparatus would continue to drive even after passing p3 in FIG. 4 (a), resulting in an unpredictable state such as smoke or fire.

Since the ripple voltage tends to decrease when the load current is small, in the present invention, the magnitude of the average voltage is added to the determination condition in order to accurately detect the deterioration of the capacitor at light load, and the ripple voltage value is a warning. If the average voltage is less than the warning value or failure value even if it is less than the value or failure value, it is determined as a warning or failure. On the other hand, you may add the structure which changes the comparison ripple voltage value Er0 according to the input current I to this invention. For example, since the ripple voltage tends to change depending on the load current so that the ripple voltage increases when the load current is large, for example, the input current I is large according to the detected input current Ix (the input current increases as the load current increases). If the comparison ripple voltage Er0 is also made to vary greatly, it is possible to prevent erroneous detection of a capacitor failure due to load current fluctuation. The comparison ripple voltage Er0 corresponding to the input current I may be stored in the storage unit 35 in advance.

In the first embodiment, the case where the input current peak phase difference, the ripple voltage, and the average voltage are all used for detecting the deterioration of the capacitor has been described. For example, only the input current peak phase difference may be used for detecting the deterioration of the voltage doubler capacitor, and only the ripple voltage may be used for detecting the deterioration of the smoothing capacitor. A ripple voltage and an average voltage may be used for detection. Further, only the voltage doubler capacitor may be subject to deterioration detection.

In the first embodiment, in order to detect the deterioration of the voltage doubler capacitor, the input current peak phase calculation unit 37 compares the phase difference θ between the measured value θx of the input current peak phase and the reference value θ0 of the input current peak phase, and the comparison input. For example, the difference between the input current peak warning value θ1 (= θ0−20 °) and the reference value θ0 of the input current peak (comparison input current peak phase difference) θ01 set by the current peak phase setting unit 44 However, since θ01 is equal to a predetermined phase (20 ° = θ0−θ1) input in advance to the comparison input current peak phase setting unit 44, this is regarded as a comparison input current peak phase difference, and the input current peak The phase difference θ between the measured value θx of the phase and the reference value θ0 of the input current peak phase may be directly compared.

In the first embodiment, the case of the double voltage rectifier circuit using the two capacitors 23a and 23b as the voltage doubler capacitor 23 has been described, but the present invention is not limited to this.
If a so-called Cockcroft-Walton circuit is used, an n-fold voltage rectifier circuit (n is a positive integer of 3 or more) may be used. FIG. 7 shows a double wave quadruple voltage rectifier circuit using four capacitors 23a, 23b, 23c, and 23d, four rectifier diodes 22a, 22b, 22c, and 22d, and a smoothing capacitor 24. The capacitor 23c is added with the charge of the capacitor 23a, the capacitor 23d is added with the charge of the capacitor 23b, and the capacitor 23c + 23d becomes a quadruple voltage. Three times, five times or more can be similarly configured.
In such a voltage doubler rectifier circuit, the deterioration of voltage doubler capacitor 23 and smoothing capacitor 24 can be detected in the same manner as in the first embodiment.

The capacitor deterioration detection circuit according to the present invention is used in an inverter circuit and other power supply circuits including a voltage doubler rectifier circuit (voltage doubler capacitor and smoothing capacitor) as a rectifier circuit, and an electronic apparatus such as an air conditioner including the inverter circuit. be able to.

DESCRIPTION OF SYMBOLS 11 ... AC power supply, 12 ... Rectification part, 13 ... Smoothing capacitor, 14 ... Ripple voltage detection part, 15 ... Load current detection part, 16 ... Conversion part, 17 ... Three-phase motor, 18 ... Motor drive part, 19 ... Control part , 20 ... storage section, 21 ... AC power supply, 22 ... rectification section, 23 ... voltage doubler capacitor, 24 ... smoothing capacitor, 25 ... input current detection section, 26 ... voltage detection section, 27 ... conversion section (inverter), 28 ... Load (3-phase motor), 29 ... inverter drive circuit, 30 ... rotation speed detection circuit, 31 ... control unit, 32 ... A / D conversion unit, 33 ... A / D conversion unit, 34 ... A / D conversion unit, 35 DESCRIPTION OF SYMBOLS ... Memory | storage part 36 ... Input current measurement part 37 ... Input current peak phase calculation part 39 ... Voltage measurement part 40 ... Ripple voltage calculation part 41 ... Average voltage calculation part 42 ... Comparison ripple voltage setting part 43 ... Comparative average voltage setting unit, 44 Comparison input current peak phase setting unit, 45... Smoothing capacitor deterioration determining unit, 46 .. double voltage capacitor deterioration determining unit, 47... Motor speed controller, 48 .. warning display controller, 49. Control unit 51. Display unit 52 52 Input circuit.

Claims (8)

To the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier with a voltage doubler capacitor, smoothes it with a smoothing capacitor, and supplies it to the load,
An input current detection unit for detecting an input current of the voltage doubler rectifier circuit, and a phase of an input current peak when the voltage doubler capacitor is normal from the input current detected by the input current detection unit and a deterioration determination of the voltage doubler capacitor An input current peak phase difference calculation unit that calculates an input current peak phase difference that is a phase difference from the input current peak phase, and based on a difference between the phase difference and a preset comparison input current peak phase difference. A capacitor deterioration detection circuit for determining deterioration of a voltage doubler capacitor.   The input current peak phase calculation unit measures an input current value at predetermined time intervals for at least a power cycle, and sets a maximum value among them as an input current peak, and a phase from an interrupt that occurs every power cycle to the input current peak. The capacitor deterioration detection circuit according to claim 1, wherein: is calculated as a phase of the input current peak. To the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier with a voltage doubler capacitor, smoothes it with a smoothing capacitor, and supplies it to the load,
An input current detection unit for detecting an input current of the voltage doubler rectifier circuit, a voltage detection unit for detecting a voltage across the smoothing capacitor, and the normal operation of the voltage doubler capacitor from the input current detected by the input current detection unit An input current peak phase calculation unit for calculating an input current peak phase difference that is a phase difference between an input current peak phase of the input voltage and a phase difference of the input current peak at the time of deterioration determination of the voltage doubler capacitor, and the voltage detection unit A ripple voltage calculation unit that calculates a ripple voltage from the voltage across the smoothing capacitor, and the voltage doubler capacitor is deteriorated based on a difference between the input current peak phase difference and a preset comparison input current peak phase difference. And determining deterioration of the smoothing capacitor based on a difference between the ripple voltage and a preset comparison ripple voltage. Deterioration detecting circuit of a capacitor to be.   The input current peak phase calculation unit measures an input current value at predetermined time intervals for at least a power cycle, and sets a maximum value among them as an input current peak, and a phase from an interrupt that occurs every power cycle to the input current peak. Is calculated as the phase of the input current peak, and the ripple voltage calculation unit measures the voltage at both ends of the smoothing capacitor every predetermined time for at least the power cycle, and detects the difference between the maximum value and the minimum value as the ripple voltage. The capacitor deterioration detection circuit according to claim 3, wherein To the voltage doubler rectifier circuit that boosts the AC power source rectified by the rectifier with a voltage doubler capacitor, smoothes it with a smoothing capacitor, and supplies it to the load,
An input current detection unit for detecting an input current of the voltage doubler rectifier circuit, a voltage detection unit for detecting a voltage across the smoothing capacitor, and the normal operation of the voltage doubler capacitor from the input current detected by the input current detection unit An input current peak phase calculation unit for calculating an input current peak phase difference that is a phase difference between an input current peak phase of the input voltage and a phase difference of the input current peak at the time of deterioration determination of the voltage doubler capacitor, and the voltage detection unit An average voltage calculation unit that calculates an average voltage from the voltage across the smoothing capacitor; and a ripple voltage calculation unit that calculates a ripple voltage from the voltage across the smoothing capacitor detected by the voltage detection unit, the voltage doubler The deterioration of the capacitor is determined only by the difference between the input current peak phase difference and the preset comparison input current peak phase difference or the input current peak phase difference. And determining based on the combination of the difference between the comparison input current peak phase difference and the difference between the average voltage and the preset comparison average voltage, and the deterioration of the smoothing capacitor is compared with the ripple voltage and the preset comparison Capacitor deterioration detection characterized by determining only based on a difference from a ripple voltage or a combination of a difference between this ripple voltage and a preset comparison ripple voltage and a difference between an average voltage and a preset comparison average voltage circuit.   The input current peak phase calculation unit measures an input current value at predetermined time intervals for at least a power supply cycle, and sets a maximum value among them as an input current peak value, from an interrupt generated every power supply cycle to the input current peak value Is calculated as the phase of the input current peak, the average voltage calculation unit measures the voltage across the smoothing capacitor every predetermined time for at least the power cycle, and calculates the average value as the average voltage, 6. The capacitor according to claim 5, wherein the ripple voltage calculation unit measures the voltage across the smoothing capacitor every predetermined time for at least a power cycle, and detects a difference between the maximum value and the minimum value as a ripple voltage. Deterioration detection circuit.   The input current peak value phase difference determination level is the comparison input current peak phase setting unit, the ripple voltage determination level is the comparison ripple voltage value setting unit, and the average voltage determination level is the comparison average voltage value setting unit. 7. The capacitor deterioration detection according to claim 5, wherein a warning value indicating that the degree of deterioration is determined to require attention and an abnormal value indicating that the degree of deterioration is determined to be a failure are set. circuit. An electronic apparatus comprising the capacitor deterioration detection circuit according to claim 1.

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