JPH0759358A - Capacitor charging current suppressor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an economical and compact inverter device that has a simple circuit configuration. [Structure] An electromagnetic switch 2, a DC reactor 3 and a diode 4 are provided between a DC power supply 1 and a smoothing capacitor 5, and pulse charging is performed to intermittently turn on the electromagnetic switch 2 for a maximum charging current. It limits the current, reduces the capacity of the DC reactor, and enables disconnection at the time of stop. [Effect] With the above configuration, the inverter device can be downsized and made economical.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device or a chopper circuit driven by an AC power source via an inverter and a rectifier driven by a storage battery like an electric vehicle, and more particularly to a charging current suppressing device for smoothing capacitors thereof.

[0002]

2. Description of the Related Art FIG. 6 is a connection circuit diagram of an embodiment of a conventional inverter, FIG. 7 is a circuit diagram of an inverter in which the electromagnetic switch of the inverter shown in FIG. 6 is replaced by a thyristor, and FIG. 8 is only a DC reactor. It is a circuit diagram of an inverter which limits an inrush current. Since a voltage source inverter uses a large-capacity capacitor as a smoothing capacitor, a large current flows at the time of startup and damages the power supply. Therefore, in the conventional method, the resistor R is connected to the capacitor charging circuit as shown in FIGS. It was designed to be short-circuited by an electromagnetic switch or thyristor when it was charged. As a method of short-circuiting, a method of detecting when the voltage for charging the capacitor is completed and the current is sufficiently reduced, a method of detecting when the voltage of the capacitor is sufficiently high, and the like are disclosed. In addition, as shown in FIG. 8, there has been one that suppresses the current by inserting a DC reactor.

[0003]

DISCLOSURE OF THE INVENTION The above-mentioned conventional method and means for suppressing the charging current of a capacitor are designed to insert a DC circuit resistance and short-circuit the resistance with an electromagnetic switch or thyristor after the charging of the capacitor is completed or disconnect the power supply from the power supply at the time of stop. Therefore, the circuit configuration becomes complicated such that an opening / closing switch for performing the operation is required. When using a DC reactor, if you use a capacitor that matches the capacity of the capacitor, you will have the problem of requiring a considerably large reactor, which has the disadvantage of complicating the system and hindering downsizing and weight reduction. There is a risk of overvoltage due to LC resonance. An object of the present invention is to provide an inverter capacitor charging current suppressing method and apparatus which has a simple circuit configuration, can be miniaturized, and is economical.

[0004]

A capacitor charging current suppressing device of the present invention is driven by a storage battery and other DC power supplies, and a contact of an electromagnetic switch, a DC reactor and a reflux are provided between the DC power supply and a smoothing capacitor. In a capacitor charging current suppressing device of a voltage type inverter device having a diode, control of current for charging the smoothing capacitor by repeating pulse power supply by intermittently opening and closing contacts of the electromagnetic switch for a predetermined period and number of times. It also has an opening / closing control means for performing the above, and it is possible to disconnect from the power supply while the inverter device is stopped by opening the contact. Further, in a capacitor charging current suppressing device of a voltage type inverter device driven by an AC power source via a rectifier and having a DC reactor between a rectifier and a smoothing capacitor, an electromagnetic switching device provided between the AC power source and the rectifier. And a switching control means for charging the smoothing capacitor by repeating pulse feeding by intermittently opening and closing the contacts of the electromagnetic switch for a predetermined period and number of times, and the electromagnetic switch The opening of the contact makes it possible to disconnect from the power supply while the operation of the inverter device is stopped.

Further, the switching control means sets a time during which the electromagnetic switch is turned on so that the maximum current flowing through the DC reactor becomes equal to or less than a preset value,
What opens and closes the contacts of the electromagnetic switch according to the time, the power supply voltage, the inductance of the DC reactor,
The maximum current flowing through the DC reactor from the electrostatic capacity of the smoothing capacitor is determined in advance with a pulse pattern such that it has a preset value, and the opening and closing of the contacts of the electromagnetic switch according to the pattern is controlled. Having a means for detecting the voltage of the smoothing capacitor, the switching control means calculates the rate of increase of the current from the difference between the voltage of the DC power supply and the voltage of the smoothing capacitor, and turns on the contact of the electromagnetic switch. That controls the electromagnetic switch by setting the ON time each time it is turned on so that the maximum current value when the current is a preset value, and the current that detects the current flowing in the DC reactor It has a detection means, and the switching control means turns on the electromagnetic switch when the current value indicated by the current detection means is 0, and turns off when the current value reaches a preset maximum value. To control the electromagnetic switch so that the switching control means turns on the magnetic switch when the current detected by the current detection means becomes equal to or lower than a preset minimum value, and reaches the preset maximum value. The capacitor charging current suppressing device of the present invention also includes a device that performs control to repeat the intermittent operation of turning off the electromagnetic switch when it becomes low.

Further, the voltage source inverter device may instead be a chopper circuit having a rectifying circuit and a smoothing capacitor, and other DC / AC converting means and DC / DC converting means.

[0007]

The charging with a limited upper limit is performed stepwise by pulse power feeding of one or a set of electromagnetic switches, so that the rush current during power reception does not become an excessive current and the electromagnetic switches stop the operation. Sometimes the circuit can be separated from the power supply.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a circuit diagram of a first embodiment of an inverter device to which the capacitor charging current suppressing method of the present invention is applied, and FIG. 2 is a circuit diagram of the second embodiment. In the first embodiment shown in FIG. 1, a storage battery 1, an electromagnetic switch 2, a DC reactor 3, a diode 4, a smoothing capacitor 5, a current detector 6, an inverter 7, an output terminal 8, It consists of a controller 9. When the electromagnetic switch 2 is turned on, the storage battery 1,
A circuit that passes through the reactor 3 and the capacitor 5 is formed,
The current due to LC resonance starts to flow. When the electromagnetic switch 2 is turned off after the lapse of a certain on-time, the current from the storage battery 1 is cut off, a reflux circuit passing through the diode 4 and the reactor 3 capacitor 5 is formed, and the resonance current is attenuated to zero. The diode conduction stops at. As a result, the capacitor is charged to a voltage determined by the time product of current. By repeatedly turning on and off the electromagnetic switch in this manner, the capacitor can be sequentially charged. Because of the pulsed power supply that is on for a short time, the inductance of the reactor may be small and there is no possibility of overvoltage. When the electromagnetic switch is turned off, this inverter device is disconnected from the power supply.

The second embodiment shown in FIG. 2 is an inverter device driven by an AC power supply 11 via a rectifier 13, and an electromagnetic switch 12 is provided on the AC power supply side without being installed in series with a reactor, and a rectifier circuit 13 is provided. It also functions as a freewheeling diode. The operation is the same as in the first embodiment.
3, 4 and 5 are diagrams showing an example of an on / off control method for the electromagnetic switch 2 and the electromagnetic contactor 12. FIG. 3 is a diagram showing a charging situation when the electromagnetic switch 2 performs pulse power supply with the same pulse length so that the charging time becomes uniform. The maximum value of the current is largest in the first pulse in which the difference between the power supply voltage and the capacitor voltage is large, and gradually decreases. When it is turned on at t ₁ , the current increases, and when it is turned off at t ₂ , the current is attenuated and the charging is stopped when it becomes 0 at t ₃ . By repeating such an operation, charging is performed up to the power supply voltage. FIG. 4 shows a case in which the on-time is optimally controlled so that the maximum values of the currents at the on-time are aligned.
In this case, charging is completed when the current does not reach the maximum value even when turned on. Specific control methods include: 1. A method of calculating the constants of circuit components in advance and setting the charging pattern. Method of detecting the capacitor voltage and setting the on-state time from the difference with the power supply voltage. As shown by the broken lines in FIGS. 1 and 2, there is a method in which the current detector 6 turns off when the current reaches a set value.

Further, in the case of detecting the current, it is possible to continuously control the current so as to fall between the maximum value and the minimum value as shown in FIG. 5, and thereby perform the efficient charging. You can

[0011]

As described above, according to the present invention, since the charging can be controlled by the electromagnetic switch for disconnection, one contactor can be omitted, and the influence of the charging current on the power supply can be reduced by the effect of the reactor. It is possible to do so, and there is an effect that the reactor can be significantly downsized.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of an inverter device to which a capacitor charging current suppressing method of the present invention is applied.

FIG. 2 is a circuit diagram of a second embodiment of an inverter device to which the capacitor charging current suppressing method of the present invention is applied.

FIG. 3 is a charging time chart showing a charging situation in which charging is controlled so as to be charged in a uniform charging time.

FIG. 4 is a time chart of charging when the charging time is optimally controlled so that the maximum value of the current during each charging becomes equal.

FIG. 5 is a time chart of charging when the charging current is continuously controlled so as to fall between a maximum value and a minimum value.

FIG. 6 is a circuit diagram of an example of a conventional inverter device.

7 is a circuit diagram of an inverter device in which the electromagnetic contactor of the inverter device of FIG. 6 is replaced with a thyristor.

FIG. 8 is a circuit diagram of a conventional inverter device using a DC reactor as a current limiting element.

[Explanation of symbols]

 1 DC power supply 2 Electromagnetic switch 3 Reactor 4 Diode 5 Capacitor 6 Current detector 7 Inverter 8 Output terminal 9 Controller 11 AC power supply 12 Electromagnetic switch 13 Rectifier

Claims (8)

[Claims] 1. A capacitor charging current suppressing device for an inverter device, which is driven by a storage battery and other direct current power supply, and which has a contact of an electromagnetic switch, a direct current reactor and a freewheeling diode between the direct current power supply and the smoothing capacitor. There is an opening / closing control means for controlling the current for charging the smoothing capacitor by repeating pulse power supply by intermittently opening and closing the contacts of the electromagnetic switch for a predetermined period and number of times, and by opening the contacts. A capacitor charging current suppressing device characterized in that the inverter device is disconnected from a power source while the inverter device is stopped. 2. A capacitor charging current suppressing device of a voltage type inverter device, which is driven by an AC power source via a rectifier and has a DC reactor and a freewheeling diode between the rectifier and the smoothing capacitor, between the AC power source and the rectifier. And a switching control means for charging the smoothing capacitor by repeating pulse power supply by intermittently switching the contact of the electromagnetic switch for a predetermined period and number of times, and A capacitor charging current suppressing device, characterized in that the inverter device is disconnected from a power supply during stoppage by opening a contact of the electromagnetic switch. 3. The switching control means sets a time during which the electromagnetic switch is turned on so that a maximum current flowing through the DC reactor becomes a preset value or less, and the electromagnetic switch is set according to the time. Claim 1 which opens and closes the contact of
Alternatively, the capacitor charging current suppressing device described in 2. 4. The switching control means predetermines a pulse pattern such that the maximum current flowing through the DC reactor from the power supply voltage, the inductance of the DC reactor, and the electrostatic capacity of the smoothing capacitor has a preset value. The charging current suppressing device for a capacitor according to claim 1 or 2, which controls opening and closing of a contact of the electromagnetic switch according to the pattern. 5. A means for detecting the voltage of the smoothing capacitor, wherein the switching control means calculates the rate of increase of the current from the difference between the voltage of the DC power supply and the voltage of the smoothing capacitor, and the contact of the electromagnetic switch. 3. The capacitor according to claim 1, wherein the electromagnetic switch is controlled by setting the ON time each time the power is turned on so that the maximum current value when the power is turned on becomes a preset value. Charge current suppression device. 6. A current detection means for detecting a current flowing through the DC reactor, wherein the switching control means turns on an electromagnetic switch when the current value indicated by the current detection means is 0, and the current value is preset. The capacitor charging current suppressing device according to claim 1, wherein the electromagnetic switch is controlled so as to be turned off when the set maximum value is reached. 7. A current detecting means for detecting a current flowing through the DC reactor, wherein the switching control means operates an electromagnetic switch when the current detected by the current detecting means becomes equal to or less than a preset minimum value. The control is repeated such that the electromagnetic switch is turned on and turned on and off when the preset maximum value is reached.
Alternatively, the capacitor charging current suppressing device described in 2. 8. The capacitor charging according to claim 1, wherein a chopper circuit having a rectifying circuit and a smoothing capacitor and other DC / AC converting means or DC / DC converting means are used in place of the voltage source inverter device. Current suppression device.