JP2009131125A - Control unit for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and stably predict remaining capacitance of a capacitor, without being affected by the external conditions, relating to a control unit for electric vehicle that includes a power converter which converts a single-phase AC into DC, and then converts the DC into AC. <P>SOLUTION: The electric vehicle control unit comprises a first power converter which converts a single phase AC into DC, a second power converter which converts DC into AC of an optional frequency, and a capacitor connected in parallel with the DC side of the second power converter and comprises a means for predicting the residual service life of the capacitor, based on the charging hours of the capacitor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an electric vehicle control device.

  In the electric vehicle control device, the smoothing capacitor installed on the DC side of the power converter and the capacitor used have a property that the capacity decreases due to deterioration over time. The conventional electric vehicle control device does not have a means for detecting the capacitance of the capacitor. Therefore, it is necessary to measure the capacitance of the capacitor by using a capacitance meter for periodic inspection and inspection, which requires time and effort. There is a problem. Various attempts have been proposed to accurately perform life prediction in order to avoid such problems (see References).

  Patent Document 1 proposes a technique for estimating the capacitance of a capacitor based on a current detection value and a voltage detection value at the time of initial charging.

  In the above prior art, since the charging time of the capacitor is affected by changes in the power supply voltage and the charging resistance value, accurate detection of the circuit requires accurate detection of the capacitor capacity.

Patent Document 2 proposes a technique for estimating the capacitor capacity from the magnitude of the voltage fluctuation of the capacitor.

In the above prior art, it is necessary to accurately detect the magnitude of the voltage fluctuation of the capacitor and the fluctuation frequency. Therefore, it is also necessary to accurately detect the circuit.

  A conventional example is shown in FIG. FIG. 8 shows a conventional control apparatus for an AC electric vehicle described in Reference 1. In FIG. 8, 1 is an overhead wire that is a single-phase AC voltage power source, 2 is a transformer that transforms the single-phase AC power supply voltage into a suitable voltage, 3 is a converter that converts the single-phase AC voltage into DC voltage, and 4 is from the converter. A smoothing capacitor for smoothing the output DC voltage, 5 is an inverter for converting the DC voltage to a variable voltage variable frequency, and 6 is a main motor which is a load device.

  Reference numeral 7 denotes a converter and inverter control circuit, and the control circuit includes a main control unit 71, a converter control unit 72, and an inverter control unit 73. A DC voltage command Ed * and a gate start command GS1 * are input from the main control unit 71 to the converter control unit 72, and an inverter frequency command Fi *, an output voltage command E * and a gate start command GS2 * are input to the inverter control unit 73. input. Converter control unit 72 and inverter control unit 73 output a gate signal.

  Here, detection values of voltage and current used for normal control are omitted.

A capacitor capacity determining circuit 8 detects an AC component from the capacitor voltage ed of the DC intermediate circuit, and estimates the capacitor capacity by the capacity estimating unit 82 from the AC input current command Is * and the modulation factor a. When the first comparator 83 determines that the estimated capacitor capacity is equal to or less than the reference value, it is determined that the capacitor capacity has decreased. The second comparator 84 determines whether or not to stop the main control.

Further, the history of the capacitor capacity estimation value, the AC input current command value Is *, and the modulation factor a is stored in the memory.

  Next, the operation will be described. In a converter using a single-phase alternating current as a power source, an AC fluctuation having a frequency twice that of the single-phase power source is generated in the capacitor of the intermediate direct current circuit during operation.

Assuming that the converter input voltage ec is a sine wave, the AC output Δid is equal to ΔId = a × Is / √2 (1)
Where, a: converter modulation factor Is: converter input current (fundamental value of fundamental wave)
Is approximately obtained. On the other hand, if the capacitor voltage ed ignores the harmonic component resulting from the switching of the converter, the voltage fluctuation ΔE is ΔE = (a × Is) / (2√2 × ω × C) (2)
Where ω: power supply angular frequency C: capacitor capacity, which is C = (a × Is) / (2√2 × ΔE × ω) (3)
It can be calculated with.
JP-A-5-308701 Japanese Patent Laid-Open No. 10-14097 Japanese Patent Laid-Open No. 06-163084

  However, there is a harmonic component due to the converter switching as described above, and the voltage fluctuation Δed of the capacitor voltage ed depends on the external circuit conditions and is actually difficult to detect with high accuracy.

  Therefore, the present invention provides a stable and easy capacitor in an electric vehicle control device having a power converter that converts a single-phase alternating current into a direct current and converts the direct current into an alternating current without being influenced by external conditions. The purpose is to perform capacity life prediction.

The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. This can be achieved by providing a means for predicting the lifetime of the capacitor based on the charging time of the capacitor in the electric vehicle control device including the capacitor.

  The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. In the electric vehicle control device including a capacitor, the means for predicting the lifetime of the capacitor can be achieved by calculating the deterioration degree of the capacitor.

The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. This can be achieved by providing a means for displaying the deterioration degree of the capacitor on the display when the deterioration degree of the capacitor exceeds a predetermined deterioration degree.

The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. In the electric vehicle control device composed of a capacitor, this can be achieved by stopping the power converter when the deterioration degree of the capacitor exceeds a predetermined deterioration degree.

  The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. This can be achieved by storing the degree of deterioration in a memory in an electric vehicle control device including a capacitor.

The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. In an electric vehicle control device composed of a capacitor, this can be achieved by performing life prediction from the change history of the degree of deterioration and the frequency of use.

  The above-described problem is connected in parallel to the first power converter that converts single-phase alternating current into direct current, the second power converter that converts direct current into alternating current of an arbitrary frequency, and the direct current side of the second power converter. In the electric vehicle control device comprising a capacitor, this can be achieved by performing life prediction from a history of at least three times from the degree of deterioration stored in the memory.

According to the present invention, in an electric vehicle control device having a power converter that converts a single-phase alternating current into a direct current and converts the direct current into an alternating current, the capacitance of the capacitor is stable and easy without being influenced by external conditions. It is possible to provide an electric vehicle control device capable of performing life prediction.

Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a first embodiment of the present invention. From the single-phase AC power source 1, the control circuit 7 for the converter and inverter is the same as that of the conventional device described above.

  In FIG. 1, 93 is a charging resistor switch for inserting a charging resistor, 94 is a charging resistor, and 95 is a charging resistor short-circuit switch for short-circuiting the charging resistor. 82a is a charging time measuring unit that measures the charging time of the capacitor, and 83a is a deterioration degree calculating unit that calculates the deterioration degree of the capacitor from the charging time of the capacitor. Reference numeral 85a denotes a memory that records a history of past capacitor charging times and capacitor deterioration levels, and 84a denotes a predicted replacement time calculation unit that calculates a predicted replacement time of the capacitor from the past history. Reference numeral 91 is an indicator for transmitting the capacitor charging time to the crew, and 92 is a monitor device for monitoring the past capacitor charging time, the degree of deterioration, and the predicted replacement time.

Next, the operation will be described. FIG. 2 is a diagram illustrating an operation at the time of initial charging in the charging time measuring unit 82. First, when the capacitor is initially charged at the time of start-up of the control device for the AC electric vehicle, the charging resistor insertion switch is turned on. When charging is completed, the charging resistor insertion switch is opened and the charging resistor short-circuit switch is turned on. T1 is then the capacitor charging time. This is stored in the memory and input to the deterioration degree calculation unit 83a. The deterioration degree calculation unit 83a calculates the deterioration degree from the reference charging time, the use limit charging time, and the charging time measurement value T1. For example, when the reference charging time is 1 second and the charging time at the design use limit is 0.9 seconds, if the measured charging time is reduced to 0.97 seconds, the deterioration degree is (1-0. 97) / (1-0.9) = 0.3 (4)
Can be calculated.

FIG. 3 shows an internal image diagram of the memory 83a. The memory stores a measurement history such as measurement date, device operating time, charging time, deterioration degree, usage frequency, and signals from the main control as a database. Comparator 86a determines that the capacitor is in an abnormal state when the degree of deterioration exceeds a predetermined predetermined design limit value, and outputs a stop signal to the main control unit to stop the power converter. The predicted replacement time calculation unit 84a calculates the predicted replacement time from the measurement history database. FIG. 4 is a list of the measurement date in the memory, the device operating time, the charging time, and the deterioration degree. FIG. 5 is a graph plotting the estimated operating time based on FIG. 4 on a coordinate axis with the apparatus operating time as the X axis and the degree of deterioration as the Y axis. The predicted life time in FIG. 5 is an intermediate value of the deterioration rate change rate calculated from the past three measurement points and operation time, and the remaining predicted life time when changing at the change rate is calculated.

For example, in three measurements of 2007/5/7, 2007/06/20, and 2007/7/18, the degree of deterioration is 0, 0.1, and 0.3, respectively. The operating time is 0, 500, and 950 hours, respectively. The intermediate value A of the deterioration rate change rate is A = (0.3-0) / (950-0) = 0.00031579 (5)
It becomes.

Based on the deterioration rate change rate A and the operating time, the remaining predicted life time Ta is Ta = (1-0.3) / A (6)
= (1-0.3) /0.00031579
≒ 2217 hours can be calculated.

FIG. 6 is a diagram in which a predicted replacement date is estimated and calculated in consideration of the average operation time from the predicted life time of FIG. A method for calculating the predicted exchange date will be described. Separately from the charging time, measure the daily device operating time, calculate the average operating time Tb per day from the average of the device operating time several days ago, and divide the expected life time Ta by the average operating time Tb per day The number of days added to the measurement date is calculated as the predicted exchange date.

The predicted replacement date when the average operating time per day is 15 hours is the predicted replacement date = July 18, 2007 + Ta / Tb (7)
= July 18, 2007 + 2217/15
= July 18, 2007 + 147.8 days
= December 12, 2007.

When the predicted exchange date corresponding to the measurement date is calculated by the method described above, as shown in FIG.
From 6/20 and 2007/7/18 and 2007/8/5, it will be September 11, 2007. Similarly, from the measurement days 2007/7/18, 2007/8/5 and 2007/9/10, May 29, 2008.

As described above, if the charging time and the latest device operating time are known, the predicted replacement date according to the usage frequency can be calculated. Reference 3 has a technique based on regression analysis, but the regression equation requires a lot of periodic or non-periodic measurement data. According to this embodiment, at least three charging time measurement points and timings are used. If the operation time is long, the predicted replacement date according to the use frequency can be easily calculated by an extremely simple calculation.

  A book comprising a first power converter for converting single-phase alternating current to direct current, a second power converter for converting direct current to alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter. In the electric vehicle control apparatus according to the embodiment, when the degree of deterioration of the capacitor exceeds a predetermined degree of deterioration, the fact can be displayed on the display 91, so that the crew can be notified of the deterioration of the capacitor.

(Second Embodiment)
FIG. 7 is a block diagram showing a schematic configuration of the second embodiment of the present invention.

This embodiment differs from the first embodiment of FIG. 1 in that the overhead line is not a single-phase AC power supply but a DC power supply and that the power converter and converter control unit for converting single-phase AC to DC are deleted. Also in the present embodiment, the expected replacement date can be calculated by measuring the charging time of the initial charging voltage ed as in the first embodiment.

1 is a block diagram showing a first embodiment of the present invention. Operation diagram during initial charging Internal image diagram of memory 83a List of measurement date, device operation time, measurement charge time, and degree of deterioration Graph plot on the coordinate axis with the operating time as the X-axis and the deterioration level as the Y-axis Figure showing the predicted replacement date taking into account the average operating time from the predicted life time Block diagram showing a second embodiment of the present invention Conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Overhead wire 2 ... Transformer 3 ... Converter 4 ... Smoothing capacitor 5 ... Inverter 6 ... Main motor 7 ... Control circuit 71 of a converter and an inverter ... Main control part 72 ... Converter control unit 73 ... Inverter control unit 8 ... Capacitor capacity determination circuit 81 ... AC component detection unit 82 ... Capacity estimation unit 83 ... First comparator 84 ... Second comparator 85 ... Memory 91 ... Display 92 ... Monitor device 93 ... Charging resistor input switch 94 ... Charging resistor 95 ... Charging resistor short circuit switch 82a ... Charging Time measuring unit 83a ... Deterioration degree calculating unit 84a ... Predictive replacement time calculating unit 85a ... Memory 86a ... Comparator

Claims (7)

Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter An electric vehicle control apparatus comprising a means for predicting a life of a capacitor based on a charging time of the capacitor.   Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter In the vehicle control device, the means for predicting the life of the capacitor calculates a deterioration degree of the capacitor, and the electric vehicle control device is characterized in that Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter An electric vehicle control device comprising: means for displaying a deterioration degree of a capacitor on a display device when the deterioration degree of the capacitor exceeds a predetermined deterioration degree. Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter In the vehicle control device, the electric vehicle control device stops the power converter when the deterioration degree of the capacitor exceeds a predetermined deterioration degree. Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter In the vehicle control device, the degree of deterioration is stored in a memory. Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter An electric vehicle control device characterized in that in a vehicle control device, life prediction is performed from a change history of deterioration degree and a use frequency. Electricity comprising a first power converter that converts single-phase alternating current into direct current, a second power converter that converts direct current into alternating current of any frequency, and a capacitor connected in parallel to the direct current side of the second power converter In the vehicle control device, the life prediction is performed from the history of at least three times from the degree of deterioration stored in the memory.

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