JPS5935533A - Power converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power converter that converts DC power into electric power, and particularly relates to a power converter that is operated in parallel with another AC power source.

As a power conversion device that converts the DC output of a DC power source into AC power and supplies it to the power system, a self-excited inverter 7' (*W having the configuration shown in FIG. 1) is considered.

Inverter 2 takes in DC power from DC power supply 1 and outputs AC power. The output of the inverter 2 is input to a filter 3 for improving the AC waveform, and the output of the filter 3 is further input to a switch 4. On the other hand, there is a control circuit 5 in the power system that has a function of operating the self-excited inverter 2 in parallel, and this control circuit 5 receives the target value Esul of the output voltage of the DC power supply 1, and voltage e
1. Detect the output voltage e8゜e, / of the inverter 2, form a gate signal G to the inverter 2 so as to operate the inverter 2 in synchronization with the power system, and also
Change the output power taken from the inverter to the voltage, a
Parallel operation with the electric wire shaft is performed by controlling the phase of the impeller output voltage so that the voltage becomes the target t [E, t.

In such a power conversion device, the magnitude of output power and output power factor change due to differences in impedance and voltage fluctuations of AC power supplies operating in parallel, and fluctuations in the size and power factor of the load connected to the AC power supply. The disadvantage is that stable and efficient operation cannot be achieved.

An object of the present invention is to provide a power converter using a self-excited inverter that can stably operate in parallel with another AC power source and output high power at a set voltage.

In order to achieve this objective, the present invention is designed to control the magnitude of the inverter output voltage and the output voltage mainly in the output power factor control circuit when the power converter is operated in parallel with another AC power source. The phase of the inverter output voltage is controlled by the control circuit and the synchronous control circuit to control the output of an arbitrary set power.

The present invention will be described in detail below using Examples.

FIG. 2 is a configuration diagram showing an embodiment of a power conversion device according to the present invention. In FIG. 2, 100 is a control circuit that forms the gate signal G of the inverter 2. In FIG. Control circuit 10
0 is the power that detects the output power from the filter 3 and the power factor, and the power factor detector 101. A voltage detector 102 detects the output voltage from the filter 3, a voltage detector 103 detects the voltage on the output side of the switch 4, and voltage detectors 104 and 101 detect the output voltage of the inverter 2. A power control circuit 10 that controls a corresponding value to a set value of output power.
5. Output voltage control circuit 106 that controls the output voltage from the filter 3 detected in 102 to the set value. Controls the output voltage from the filter 3 detected in 102 to the voltage on the output side of the switch 4 detected in 103. Output control circuit 107, 10
Power factor control circuit 108 which controls a value corresponding to the output power factor detected in step 1 to the power factor set value. The gate signal forming circuit 112 for operating the inverter 2 in synchronization with the voltage on the output side of the switch 4 applies the synchronous 1M signal synchronized to the inverter 2 and the voltage of the AC power supply running in parallel to control the current flow. A synchronization control circuit 109 for controlling the inverter frequency by outputting a component perpendicular to the synchronization number 1 from the source pressure; an oscillation circuit 110 for controlling the output frequency of the inverter 2; Voltage control circuit 111. tio
A gate amplifier amplifies the signal applied from the gate signal forming circuits 112 and 112 forming No. 16 which drives the inverter 2 according to the signal applied by the circuit and the signal input by the input circuit 111. 113, switching circuits 114 and 115 for switching the input consumption of the oscillation circuit 110, and a switching circuit 116 for switching the target value of the voltage control circuit.

The operation of the second embodiment of the present invention will be explained according to the operation explanatory diagram shown in FIG. In Fig. 3, after starting the inverter 2 and raising the output voltage of the filter 3, the switch 4 is closed and the
This shows the control details at each point in time when performing parallel operation with the side source. During the period from time 11 to time 13, from when the inverter 2 is started to raise the output voltage (A,) and before parallel operation with another AC power source, the switching circuit 116 is connected to the circuit b, and the switching circuit 116 is connected to the circuit b. 114 and 115 are connected to the circuit a. For this reason, the voltage 16 control circuit 11
A voltage equal to the difference between the output signal 1 of the output voltage control circuit l/07 and the output signal of the voltage detector 104 is applied to the input of the voltage detector 104.
The output signal of the synchronous control circuit 109 is applied to the oscillation circuit 1100 input. Therefore, the output voltage of the inverter 2 is controlled by the output voltage control wholesale circuit 107 so that the output voltage of the filter 3 matches the voltage on the output side of the switch 4, that is, the voltage of another AC power supply operated in parallel. When the control is complete, the output frequency of the inverter 2 is controlled by the synchronous control circuit 109, and the phase of the output voltage of the filter 3 matches the voltage on the output side of the switch 4, that is, the phase of the other 55 current nearby sources operating in parallel. controlled as follows.

Note that the output voltage (A) from time jl to time t2 can be gradually raised from 0 by applying a signal to the voltage control circuit 111 from a sequence circuit (not described) to perform a so-called soft start.

In order to operate inverter 2 in parallel with another AC power supply, t3
At this point, an ON command is given to the switch 4 from the sequence control circuit to close the switch 4. At this time, the switching circuit 106 switches from b to C, and the switching circuit 114 switches from b to a. Therefore, 1 voltage, which is the difference between the output 1δ of the power factor control circuit 108 and the output signal of the voltage detector 104, is applied to the input of the voltage control circuit 111, and the power of the loss circuit 110 is applied to the power control circuit 111. 105 and the phase width pressure of the output signal of the synchronous IIJIJf+11 circuit 109 are stamped. Therefore, the output voltage (A) of the inverter 2 is controlled by the power factor control circuit 108, which controls the output voltage of the inverter 2 so that the power factor on the output side of the filter 3 matches the power factor setting directly, and The output-frequency control of No. 2 is performed by both the synchronous control circuit 109 and the power control circuit 105, so that the inverter 2 is synchronized with another AC power source operated in parallel, and the power (B) on the output side of the filter 3 is The frequency, that is, the phase of the output voltage of the inverter 2 is controlled so as to match the output setting value.

Note that the output power control and power factor control from t3 to t4 are performed by the oscillation circuit 110, !, from the sequence circuit whose description is omitted, similarly to the output voltage rise from t□ to 12. By giving a signal to the pressure control circuit 111 and controlling it to suppress sudden changes in the output signal in response to sudden changes in poison input No. 1d, the output power 9 is gradually increased from 0 to the set value as shown in FIG. 3(B). .

As is clear from the above, before the switch 4 is closed, the output voltage of the output voltage/control circuit 107 and the synchronous control circuit 1 109 and the output voltage of the filter 3 are the same as the voltage of the other power source θbi which operates in parallel. The power factor is controlled to match and be in the same phase as the power factor control circuit 108, the synchronous control circuit 109, and the power control circuit 105 during parallel operation to prevent disturbance when the switch 4 is closed. The inverter 2 is controlled so that the resulting force is output.

For this reason, even if the voltage magnitude, impedance, load power factor, etc. of other AC power supplies that operate in parallel differ, there is an effect that the parallel operation can be performed stably and the set power can be output.

Note that when performing independent operation due to failure of another AC power supply operating in parallel, etc., the switching circuit 116 is set from a1115 to b. The output voltage of the filter 3 is controlled by the output voltage control circuit 106 to match the voltage setting value, and the mantissa becomes a value determined within the oscillation circuit 110.

FIG. 4 shows another embodiment. The difference from the embodiment shown in FIG. 2 is that a switching circuit for switching the gain is provided in the output voltage control circuit 107, and during parallel operation, the gain of 107 is lowered, and the output of 107 and the output of power factor control circuit 108 are 1g of sum
The output voltage of the inverter 2 is controlled by the number. Note that the switching circuit 117 is b1 before parallel operation.
Switch to b during parallel operation. According to this embodiment, there is an effect that the output voltage of 4m, 107, whose load power factor is significantly different from the set power factor, is controlled within the limit value.

FIG. 5 shows another embodiment. The difference from the embodiment shown in FIG. Before parallel operation, the switching circuit 114 is connected to b, so it outputs without shifting the phase of 118, and during parallel operation, 114 is connected to a, and the detected width pressure is adjusted according to the output signal of the -force control circuit. Output with phase shift.

As is clear from the above, according to the present invention, the father's
You can see the effect of being able to supply the set power at the set power factor by operating in parallel with one power source.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a power conversion device, Fig. 2 is a block diagram of an example of the central jlIi of the present invention, Fig. 3 is a control operation explanatory diagram, and Figs. 4 and 5 are other actual images of the present invention. FIG. 2 is an example block diagram.

Claims (1)

[Scope of Claims] 1. In a power conversion device that converts the direct current power of a direct current power source into alternating current power and operates in series with another alternating current power source, an inverter that converts direct current power into alternating current power; A power control circuit that controls the power or output power of the power converter, a power 4 control circuit that controls the output power factor of the power converter, a voltage control circuit that controls the magnitude of the output voltage of the power converter, and a power converter that controls the output power factor of the power converter. A synchronous control circuit that operates in synchronization with the AC power supply is installed. Before parallel operation, the output voltage control circuit controls the inverter voltage magnitude and the synchronous control circuit controls the phase of the output voltage. During parallel operation with the AC power supply, A power conversion device characterized in that a power factor control circuit controls the magnitude of an inverter voltage, and a power control circuit and a synchronous control circuit control the phase of the inverter voltage. 2. In claim 1, the output voltage control circuit has a function of controlling gain, and increases the gain to control the magnitude of the inverter voltage before parallel operation, and decreases the gain during parallel operation. A power conversion device characterized in that the magnitude of an inverter voltage is mainly controlled by a power factor control circuit.