JP2677804B2 - How to start / stop the inverter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinated control method between a DC power supply unit and an inverter, and more particularly, between a converter and an inverter in an electric vehicle having a main circuit including an inverter and a converter. Suitable start-up of inverter device used for coordinated control of
Regarding stop method. [Prior Art] In general, these controls in an electric vehicle having a main circuit composed of a DC power supply unit and an inverter and the like need to perform coordinated control of the DC power supply unit and the inverter.
The inverter is started after the DC power supply is started. Then, this kind of control method according to the conventional technique operates the inverter on condition that the DC output voltage of the DC power supply unit is within a certain voltage range. As a conventional technique of this control method, for example, the technique described in Japanese Patent Laid-Open No. 56-107709 is known. [Problems to be Solved by the Invention] However, the prior art does not consider the case where the output target value pattern from the inverter to the DC power supply unit changes due to the speed of the vehicle or the like, and the inverter stops. Since the output voltage of the DC power supply unit is constant regardless of the output voltage target value pattern, there is a problem in that the operable range of the inverter changes depending on the vehicle speed or the like. In other words, if an overhead line power failure occurs during power running (regeneration) of the vehicle, the inverter consumes (supplies) power, so the voltage across the terminals of the filter capacitor connected between the DC power supply and the inverter is ,
If the inverter goes down (rises) in a short time, the DC power supply may be burned out by the inrush current to the filter capacitor when the overhead power line is restored, or the filter capacitor may be punctured due to overvoltage. Although it is necessary to stop the inverter, in the above-described conventional technique, the inverter stop control may be delayed due to a change in the inverter operable range, and the DC power supply unit may be burned or the filter capacitor may be punctured. There was a problem. An object of the present invention is to provide a method for starting / stopping an inverter device, which solves the above-mentioned problems of the prior art and can reliably start / stop the inverter. [Means for Solving the Problems] According to the present invention, the above object is to provide an apparatus including a power supply section for outputting direct current and an inverter connected through a capacitor connected in parallel with the direct current side of the power supply section. Monitoring the voltage of the capacitor, calculating the difference between the obtained monitoring voltage and the DC-side output voltage target value instructing the power supply unit,
This is achieved by activating the inverter when the absolute value of the difference is a fixed value or less and stopping the inverter when the absolute value is a fixed value or more. [Operation] The inverter sends the output voltage target value to the DC power supply,
The DC power supply unit receives this and outputs a DC voltage. On the other hand, the inverter constantly monitors the capacitor voltage connected to the DC side of the DC voltage section, and when the absolute value of the difference between the capacitor voltage obtained by this monitoring and the output voltage target value is a certain value or more, The operation of the inverter is stopped, and the inverter is put into operation only when the absolute value of this difference is equal to or less than a certain value. [Embodiment] An embodiment of a method for starting and stopping an inverter device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment in which the present invention is applied to an electric vehicle of a PWM converter + VVVF inverter control system, and FIG. 2 is a diagram showing a relation between a converter actual output voltage and an inverter operable area in FIG. Is. In FIG. 1, 1 is a train line, 2 is a current collector, 3 is a transformer, 4 is a converter body, 5 is a converter gate control device, 6 is a converter gate PWM unit, 7 is a filter capacitor, 8 is an inverter body, 9 is an inverter gate control device, 10 is an inverter gate PWM unit, 11 is a DC voltage target value generation unit, 14
Is a gate-on signal generator, 15 is an induction motor, 16 is a pulse generator, and 17 is a V _c ^* generator. As shown in FIG. 1, the electric vehicle of the PWM converter + VVVF inverter control system is a DC power source composed of a transformer 3, a converter body 4 and a converter gate control device 5 which are connected to a train line 1 via a current collector 2. Section, a filter capacitor 7, an inverter device including an inverter body 8 and an inverter gate control device 9, and an induction motor 15
And a pulse generator connected to this induction motor 15
16 and. The converter gate control device 5 is configured to include a converter gate PWM unit 6, and the inverter gate control device 9 is an inverter gate.
A PWM unit 10, a DC voltage target value generation unit 11, a gate-on signal generation unit 14, and an inverter output voltage target value V _c ^* generation unit 17 are provided. In the electric vehicle configured as described above, during power running, the AC power supplied from the train line 1 via the current collector 2 is:
The voltage is stepped down by the transformer 3, and the converter gate control device 5
Is converted into a DC voltage by the converter main body 4 which operates by the gate pulse from and the filter capacitor 7 is charged. The inverter body 8 operates by the gate pulse from the inverter gate control device 9, and the converter body 4
The DC motor applied from the filter capacitor 7 through the filter capacitor 7 is converted into three-phase AC to drive the induction motor 15. Rotational speed of the induction motor 15 (rotor frequency) f _r is
It is detected by the pulse generator 16, taken into the inverter gate controller 9, and used for controlling the inverter body 8. During regenerative braking, the regenerative AC power from the induction motor 15 is converted into direct current by the inverter body 8 to charge the filter capacitor 7. And the converter body 4
Converts this direct current power into alternating current and regenerates the electric power in the train line 1 via the transformer 3 and the current collector 2. Thereby, the electric vehicle can obtain the braking force. Next, the flow of various signals when the above operation is performed will be described. The inverter gate control device 9 is a pulse generator.
The rotation frequency (rotor frequency) f _r of the induction motor 15 is always taken in from 16, and the inverter frequency target value f _INV ^{* is} obtained by adding the slip frequency target value f _s ^{* and} this rotation speed f _r ^.
Occurs. The inverter frequency target value F _INV ^* is sent to the V _c ^* generation unit 17, which generates the inverter output voltage target value V _c ^* , the DC voltage target value generation unit 11, and the inverter gate PWM unit 10. The V _c ^* generation unit 17 is a calculator or a function circuit, calculates the inverter output voltage target value V _c ^* from the inverter frequency target value f _INV ^* , and sends it to the inverter gate PWM unit 10. Further, the DC voltage target value generation unit 11 is an arithmetic unit or a function circuit, calculates a DC voltage target value E _d ^* for the converter unit, that is, the DC power supply unit from the inverter frequency target value f _INV ^* , and a converter gate control device. It is sent to the converter gate PWM section 6 in 5. This DC voltage target value E _d ^* is controlled so as to change according to the value of the inverter frequency target value f _INV ^* . This is one of the control methods for controlling the constant torque of the induction motor 15 over a wide speed range in this type of electric vehicle. This DC voltage target value E _d ^* does not have to be a function of the above-mentioned inverter frequency target value f _INV ^* , and for example, the electric vehicle speed, the rotation speed of the induction motor, the rotor frequency of the induction motor, the slip frequency of the induction motor. , May be controlled as a function of time, etc. The converter gate PWM unit 6 uses the above-mentioned DC voltage target value E
_The gate pulse commanded to the converter body 4 is controlled by _d ^* and the power factor target value PF ^* . A filter capacitor 7 is connected between the converter body 4 and the inverter body 8, and the voltage across the terminals of the filter capacitor 7 is
That is, the actual output voltage E _d of the converter body 4 is taken in by the inverter gate control device 9, and the difference between the actual output voltage E _d and the DC voltage target value E _d ^* is sent to the gate-on signal generator 14. To be The gate-on signal generation unit 14 outputs the gate-on signal to the inverter gate PWM unit 10 only when the difference is within a certain range, for example, in the range of −200V to + 200V, that is, only when the absolute value of the difference is 200V or less. To send. The inverter gate PWM unit 10 keeps the above-described inverter frequency target value f _INV ^* and the inverter output voltage target value V only while the gate-on signal is given from the gate-on signal generator 14.
_A gate pulse is generated according to _c ^* to operate the inverter body 8. As a result, the induction motor 15 is drive-controlled. The above-described operation is an operation during normal power running, but the embodiment of FIG. 1 can be similarly operated during regeneration. In the above-described operation, the relationship between the DC voltage target value E _d ^* , the actual output voltage E _d , the inverter frequency target value f _INV ^*, and the operation / stop of the inverter is shown in FIG. 2, which will be described below. . In FIG. 2, the DC voltage target value E _d ^* changes depending on the value of the inverter frequency target value f _INV ^* as described above, and the DC voltage target value E _d ^* is set to a large value in a high frequency range. It is set by the value generator 11. Since the embodiment shown in FIG. 1 operates as described above, when the normal power running / regeneration is started, first, the converter main body 4
When the voltage of the filter capacitor 7 enters the inverter operating region 21, the inverter body 8 starts operating and starts supplying electric power to the induction motor 15. If an overhead power line power failure occurs during power running, that is, a power line 1 power failure, the induction motor 15 consumes power through the inverter body 8, so that the voltage across the terminals of the filter capacitor 7, that is, the actual converter body 4. The output voltage E _d begins to drop sharply. This actual output voltage is the DC voltage target value E _d
^{If the voltage} drops from ^* to a certain value or more, the inverter operating area 21
Therefore, the inverter stop region 22 is entered from the gate on signal generator 14 to the inverter PWM
When the gate-on signal given to the section 8 is turned off, the inverter 8 stops its operation and prevents the actual output voltage E _d of the converter body 4 from further decreasing. The overhead line power is restored and the actual output voltage of the converter body 4
When E _d rises and the difference from the DC voltage E _d ^* becomes a certain value or less, the applied voltage of the inverter body 8 enters the inverter operation area 21 again, and the inverter body 8 starts operating. To do. When an overhead line power failure occurs during regeneration, the induction motor 15 supplies electric power to the converter body 4 via the inverter body 8 as opposed to during power running, so that the terminal voltage of the filter capacitor 7, that is, The actual output voltage E _d of the converter body 4 starts to rise rapidly. When this voltage rises from the DC voltage target value E _d ^* by a certain value or more, the applied voltage of the inverter main body 8 enters from the inverter operation area 21 to the inverter stop area 23, and by the above operation,
The inverter body 8 stops its operation and prevents the actual output voltage E _d , which is the terminal voltage of the filter capacitor 7, from further increasing. When the overhead power line is restored, the actual output voltage E _d
When the voltage drops and the difference from the DC voltage target value becomes a certain value or less, the voltage applied to the inverter body 8 enters the inverter operation area 21 again, and the inverter body 8 starts its operation. Although the above-described embodiments of the present invention have been described as being applied to an electric vehicle, the present invention is applicable to any power supply unit as long as it includes a DC power supply unit and an inverter. can do. [Effects of the Invention] As described above, according to the present invention, the inverter can be safely and reliably started by the completely same control method during both normal startup and power failure without unnecessarily performing a protective operation. It can be stopped.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an embodiment in which the present invention is applied to an electric vehicle of a PWM converter + VVVF inverter control system, and FIG.
The figure is a diagram showing the relationship between the converter actual output voltage and the inverter operable area in FIG. 1 …… train line, 2 …… current collector, 3 …… transformer, 4 ……
Converter main body, 5 ... Converter gate control device, 6
...... Converter gate PWM section, 7 …… Filter capacitor, 8 …… Inverter body, 9 …… Inverter gate controller, 10 …… Inverter gate PWM section, 11 …… DC voltage target value generation section, 14 …… Gate on signal Generator, 15 ……
Induction motor, 16 …… Pulse generator, 17 …… V _c ^* generator.

Claims (1)

(57) [Claims] A device comprising an inverter connected via a power source for outputting direct current and a capacitor connected in parallel with the direct current side of the power source, the voltage of the capacitor being monitored, and the obtained monitoring voltage and the power source A difference from the commanded DC output voltage target value is calculated, the inverter is started when the absolute value of the difference is a fixed value or less, and the inverter is stopped when the absolute value is a fixed value or more. How to start / stop the inverter device. 2. The DC side output voltage target value is a function of a target value of an inverter frequency, an electric vehicle speed, a rotation speed of an induction motor, a rotor frequency of an induction motor, a slip frequency of an induction motor or time. A method for starting and stopping the inverter device according to the first aspect of the invention.