JPS63234867A - Power throw-in circuit of inverter device - Google Patents

Abstract

PURPOSE:To prevent a current-limiting impedance in abnormality from damage and to prevent a rectifier and an inverter from breakage, by controlling the charging time of a smoothing capacitor. CONSTITUTION:When power supply is preformed, a relay drive circuit 8 actuates to turn ON a relay 11 with a timing signal of a time control means 7 and a smoothing capacitor 3 is charged by the DC output of a rectifier 2. The time control means 7 counts the time from the ON point of time of the relay 11. In case smoothing capacitor 3 does not reach the specified voltage value after a preset time is over and no output data from a voltage detecting means 5 is inputted, this set time length is set up to the value longer than the time constants of a current-limiting impedance 12 and the smoothing capacitor 3. Even if this preset time passes, in case the smoothing capacitor 3 is not charged up or it is still in charging, it is judged that the main circuit is abnormal. The relay 11 is then turned OFF with a timing signal of the time control means 7 through the relay drive circuit 8 and AC input from an AC power source 1 is interrupted to stop the operation immediately.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention performs a current limiting operation when power is turned on in an inverter device that rectifies an AC power supply with a rectifier and smoothes the DC power with a smoothing capacitor and converts it into AC with an inverter. This inverter device is suitable for power-on circuits of inverter devices, and is particularly suitable for preventing burnout of the current limiting impedance in the event of short circuit abnormalities, and in preventing destruction of rectifiers, etc. due to inrush current in the event of abnormalities such as failure of circuit components or poor wiring or contact. Regarding power-on circuit.

[Conventional technology]

In the conventional power-on circuit of this type of inverter device, a current-limiting impedance is inserted between the rectifier and the smoothing capacitor in order to limit the excessive charging current of the smoothing capacitor that forms the inrush current when the power is turned on. After a predetermined period of time has elapsed or a predetermined charging voltage has been reached, the short circuit of the current limiting impedance is short-circuited using a relay or the like to enter normal operation. A power-on circuit for this type of rectifier circuit is described in Japanese Patent Laid-Open No. 58-9573.

[Problem that the invention seeks to solve]

The above conventional technology involves short-circuiting of the current-limiting impedance according to the surge withstand capacity of the rectifying element, burnout of the current-limiting impedance in the event of a short-circuit abnormality, and failures due to inverter device operation in the event of an abnormality such as failure of circuit components or poor wiring or contact. Therefore, if the short-circuit operation is fast due to constant short-circuiting at a constant predetermined time or predetermined charging voltage, a large capacity current-limiting impedance is required, and if the short-circuit becomes abnormal, If the current limiting impedance burns out, or if an abnormality occurs such as a failure of a circuit component, a wiring error, or a poor contact, there are problems such as damage to the rectifier or inverter.

An object of the present invention is to provide a power-on circuit for an inverter device that can reduce the capacity of the current limiting impedance and prevent burnout of the current limiting impedance and damage to the rectifier and inverter in the event of an abnormality.

[Means for solving problems]

The above purpose is to provide an inverter device consisting of a rectifier composed of diodes to rectify the alternating current of the alternating current power source, a smoothing capacitor to smooth the direct current output, and an inverter to convert the direct current output to alternating current. A relay that connects a current-limiting impedance between the relay, a relay that directly connects the AC power supply and the rectifier, a voltage detection means that detects the voltage across the smoothing capacitor, and a voltage detection time of the voltage detection means that is managed to detect abnormalities. This is achieved by a power-on circuit for an inverter device that is provided with a means for determining the timing of turning on and releasing the relay, as well as means for controlling the timing of turning on and releasing the relay.

[Effect]

In the power-on circuit of the inverter device described above, when the power is turned on, the smoothing capacitor is charged through a current-limiting impedance to suppress the inrush current, and by managing the time for charging the smoothing capacitor, the smoothing capacitor is limited to a predetermined voltage or higher. By separating the current impedance and controlling the operation of directly connecting the AC power source and the rectifier, the capacity of the current limiting impedance can be reduced, and if the charging voltage is insufficient for the charging time of the smoothing capacitor, Since the AC power source and the rectifier are not directly connected, safety is maintained because inrush current does not flow even in the event of an abnormality such as poor contact.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a block diagram showing an embodiment of a power supply circuit for an inverter device according to the present invention. In Figure 1, 1
2 is an AC power supply, 2 is a rectifier composed of a rectifying diode for rectifying AC, 3 is a smoothing capacitor for smoothing DC output, and 4 is an inverter (inverter) for converting DC to AC.

5 is a voltage detection means for detecting the voltage across the smoothing capacitor 3; 6 is a drive circuit for driving the inverter 4; 7 is a voltage detection means for managing the voltage detection time of the voltage detection means to determine an abnormality and turning on/off the relay. 8 is a drive circuit for the relay 11 which operates according to the output timing of the time management means 7, and 9 is a drive circuit for the relay 10. 10 is a relay (contact) that short-circuits the current limiting circuit and directly connects the AC power supply 1 and the AC input terminal of the rectifier 2; 11 is a relay (contact) that connects the current limiting impedance 12;
Relay (contact) to disconnect, 12 is AC power supply 1 and rectifier 2
The series circuit of the current limiting impedance 12 and the relay 11 constitutes a current limiting circuit.

FIG. 2 is a timing chart when the power of FIG. 1 is turned on. Further, FIG. 3 is a flowchart when the power is turned on in FIG. 1. Next, the operation of the configuration shown in FIG. 1 will be explained with reference to FIGS. 2 and 3. First, when the power is turned on, the relay drive circuit 8 is activated by the timing signal from the time management means 7, and the relay 11 is turned on. is input, and the smoothing capacitor 3 is charged from the DC output of the rectifier 2. The charging voltage of this smoothing capacitor 3 is detected by the voltage detection means, and the smoothing capacitor 3
Determine whether the voltage across the terminal exceeds a predetermined voltage value E,
When the predetermined voltage value E is exceeded, the information is sent to the time management means 7.
At the same time, it is output to the drive circuit 6 of the inverter 4. Then, based on the output information from the voltage detection means 5, the time management means 7 outputs a timing signal to the relay drive circuit 8 and relay drive circuit 9 to operate them when the voltage across the smoothing capacitor 3 reaches a predetermined voltage E. As a result, the relay 11 of the current limiting circuit is turned off, and at the same time, the relay 10 that short-circuits the current limiting circuit is turned on, and at this time, the AC N source 1 and the AC input terminal of the rectifier 2 are directly connected, and at the same time, the current limiting impedance is At 12, it is disconnected and normal operation begins. The drive circuit 6 of one inverter 4 is activated based on the output information from the voltage detection means when the voltage across the smoothing capacitor 3 exceeds a predetermined voltage E, thereby causing the inverter 4 to operate normally. AC output can be changed.

The time management means 7 is composed of a microcomputer or a timer, and counts the time from when the relay 11 of the current limiting circuit is first turned on when the power is turned on. If the voltage across the smoothing capacitor 3 does not reach the predetermined voltage value E and the output information from the voltage detection means 5 is not input after the elapsed time, this predetermined time T is determined by the time constant of the current limiting impedance 12 and the smoothing capacitor 3. By setting it to a larger appropriate value, if the voltage across the smoothing capacitor 3 does not reach the predetermined voltage value E even after the predetermined time T has elapsed, and charging is not possible or charging is in progress, the connection of the main circuit can be changed. When it is determined that there is an abnormality such as a mistake or poor contact, the relay 11 of the current limiting circuit is turned off via the relay drive circuit 8 in response to a timing signal from the time management means 7, thereby cutting off the AC input from the AC power source 1. and immediately stop operation.

According to this embodiment, by using a simple voltage detection means and a time management means using a microcomputer, a timer, etc., the smoothing capacitor 3 can be set to a predetermined voltage even when there is an abnormality such as a failure of a circuit component or a poor connection or contact. When the value E is not reached or the charging time takes an abnormally long time, it is possible to determine that there is an abnormality in the device and to stop the operation while it is safe. Furthermore, even if an abnormality occurs in the relay that short-circuits the current-limiting circuit during normal operation, the current-limiting impedance will not be burnt out because the current-limiting impedance is disconnected.

〔Effect of the invention〕

According to the present invention, since it is possible to manage the charging time of the smoothing capacitor when turning on the AC power of the inverter device,
You can easily reduce the current-limiting impedance by setting the short-circuit time of the current-limiting impedance according to the surge resistance of the rectifier and the time constant of the circuit. In addition to improving safety by stopping the inverter by determining an abnormality based on the charging voltage and charging time of the smoothing capacitor, the current limiting impedance is disconnected during normal operation, so even if a short circuit or other abnormality occurs, it will not burn out. There are results such as never.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the power supply official circuit of an inverter device according to the present invention, FIG. 2 is a time chart when the power is turned on as shown in FIG. 1, and FIG. 3 is a flowchart when the power is turned on as shown in FIG. It is. 1... AC power supply, 2... Rectifier, 3... Smoothing capacitor, 4... Inverter (inverter), 5...
Voltage detection means, 6... Inverter drive circuit, 7... Time management means (timing control circuit), 8.9... Relay drive circuit, 10.11... Relay (contact), 12.
・]Current-limiting impedance. Figure 1 z2 $ 2 Figure 3

Claims (1)

[Claims] 1. In an inverter device consisting of a rectifier composed of diodes that rectify alternating current from alternating current, a smoothing capacitor that smoothes the DC output, and an inverter that converts the direct current to alternating current, there is a connection between the alternating current power source and the rectifier. A relay that connects a current-limiting impedance that suppresses inrush current when the power is turned on, a relay that connects directly between the AC power supply and the rectifier, a voltage detection means that detects the voltage across the smoothing capacitor, and the voltage of the voltage detection means. A power-on circuit for an inverter device, comprising means for determining an abnormality by managing detection time and controlling timing for turning on and releasing the relay.