JPH06225539A - Semiconductor power converter - Google Patents

Abstract

PURPOSE:To materialize the improvement of loss generated in a semiconductor power converter used for a power system or the like and the improvement of follow-up property to a command value at the same time. CONSTITUTION:This converter is provided with inverters 4A-4C each composed of a control circuit 3, which operates an output command value, using the load current IL detected by CT1 for current detection and the power voltage VS detected by PT2 for detection of the voltage of a power source, and a plurality of semiconductor elements for power, which operate by the output command value operated in the control circuit 3 and are different in operation frequency area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of loss and response of a semiconductor power converter.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing an example of an active filter device announced in Mitsubishi Electric Technical Report Vol. 62 No. 6 (P15-20). In this figure, 1 is a load current detection CT (measuring instrument current transformer) for detecting a load current, and 2 is a power supply voltage detection P for detecting a power supply voltage.
T (instrument transformer), 3 is a control circuit that calculates a control signal from the load current detected by the load current detection CT1 and the power supply voltage detected by the power supply voltage detection PT2, and 4 is this control circuit 3. The inverter unit is a semiconductor device configured by a power semiconductor element that is controlled and performs power conversion. Further, 5 is a semiconductor power conversion device, 6 is a load, and 7 is a step-up transformer. Furthermore, I _L
Indicates a load current and V _S indicates a power supply voltage.

Next, the operation will be described. The semiconductor power conversion device 5 having the above configuration is used as a device for suppressing the reactive power and the harmonic current generated by the load 6, and for suppressing the fluctuation of the power supply voltage, and the load current detection CT1 detects the load current I _L and the power supply voltage detection. Power supply voltage V by PT2 for
_S is detected, and the reactive power generated by the load 6 and the fluctuation of the power supply voltage are calculated. Then, the control circuit 3 generates a control signal for suppressing fluctuations in reactive power, harmonic current, and power supply voltage, and the inverter unit 4 transmits and receives power to load the load 6.
This suppresses the reactive power and harmonic current that are generated, and suppresses fluctuations in power supply voltage.

[0004]

Since the conventional semiconductor power conversion device 5 is configured as described above, the control circuit 3
It was necessary to make the output of the power semiconductor element follow the output command value having a wide frequency range calculated by. In such a device configuration, for example, when it is required to follow the frequency range in which the output command value is high, it is necessary to increase the operating frequency of the power semiconductor element, and the loss of the power semiconductor element increases. Further, for example, in order to reduce the generated loss of the power semiconductor element, it is necessary to lower the operating frequency of the power semiconductor element, and there is a problem that followability to a frequency region where the output command value is high is hindered.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a semiconductor power conversion device that simultaneously achieves loss reduction of a power semiconductor element and high-speed followability to a command value. And

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a control circuit for calculating an output command value of a semiconductor power converter and a plurality of semiconductors operating in different operating frequency regions according to the output command value calculated by the control circuit. A device is provided.

[0006]

In the semiconductor power conversion device according to the present invention, a plurality of semiconductor devices having different operating frequency regions which operate in a frequency region in which the generated loss is small corresponding to the output command value calculated by the control circuit operate. Therefore, by inputting the output command value to the semiconductor device having a plurality of different operating frequency regions, it is possible to follow the output command value in a wide frequency region without increasing the generated loss of the entire device.

[0007]

[Embodiment 1] FIG. 1 shows an embodiment 1 of the present invention in which a semiconductor device for performing three types of power conversion is provided and operated as an active filter. In FIG.
Reference numeral 1 is a load current detection CT, 2 is a power supply voltage detection PT, 3 is a load current I detected by the load current detection CT 1.
A control circuit for calculating and generating a control signal (command value) from the power supply voltage V _S detected by _L and the power supply voltage detection PT2. These circuits are the same as those in the conventional example (FIG. 5). 4A to 4C are three types of semiconductor devices that perform power conversion, 4A is an inverter unit for operating in a low frequency region near the power source fundamental wave, 4B is an inverter unit for operating in a frequency region of several hundreds Hz, and 4C is several kHz. Up to the high frequency region operation inverter section, 5 is a semiconductor power converter, and 6 is a load.

Next, the operation of the first embodiment will be described. CT1 for load current detection and PT2 for power supply voltage detection
The output command value is calculated in the control circuit 3 according to the detected amount of 1 and is given to the inverter units 4A to 4C. The inverter unit 4A having a low operating frequency region follows a low frequency region of the output command value, the inverter unit 4B follows a medium frequency region of the output command value, and the inverter unit 4C follows a frequency region of the high output command value. By doing so, a total output that follows the command value output from the control circuit 3 can be obtained without increasing the generated loss of the entire device, and high frequency, reactive power, or negative-phase current compensation, etc. can be applied to the semiconductor power conversion device 5 Done by.

[Embodiment 2] FIG. 2 is a configuration diagram of a semiconductor power conversion device 5 showing Embodiment 2 of the present invention. Example 1 above
Then, the output command value is input to the inverter units 4A to 4C, but instead of this, in the second embodiment of FIG. 2, the output command values are input to the bandpass filters 6A to 6C that match the operating frequency regions of the inverter units 4A to 4C. Input and inverter section 4A-4
By converting to a command value most suitable for C, the followability to the output command value of the control circuit 3 can be improved. The basic operation is the same as that of the first embodiment, and will be omitted.

[Third Embodiment] FIG. 3 is a configuration diagram of a semiconductor power conversion device 5 according to a third embodiment of the present invention. Example 1 above
In this case, the outputs of the inverter units 4A to 4C are added as they are. However, in general, the higher the frequency component amount is, the lower the ratio of the control amount to the control amount is. By boosting the outputs of 4B and 4C by boosting transformers 7B and 7C, it is possible to reduce the DC voltage and the device capacity of the inverter units 4B and 4C. The basic operation is the same as that of the first embodiment, and will be omitted.

[Embodiment 4] FIG. 4 is a block diagram of a semiconductor power converter 5 showing Embodiment 4 of the present invention, showing a single inverter, and 8 is a DC voltage source. Examples 1 to 3 above
In the above, an example in which a semiconductor device that performs power conversion is operated as an active filter is shown.
Then, for example, in the control circuit 3, it is possible to operate as a sine wave output inverter that outputs a rectangular wave output by the inverter unit 4D for the low frequency region and outputs a harmonic component output and an output reference value by the inverter unit 4E for the high frequency region. Is.

[0012]

As is apparent from the above description, according to the semiconductor power conversion device of the present invention, since a plurality of semiconductor devices operating in the frequency range with less power loss are connected in parallel, the power loss of the entire device is reduced. It is possible to quickly follow up the control command value in a wide range of frequency regions without increasing.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a semiconductor power conversion device of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the semiconductor power conversion device of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the semiconductor power conversion device of the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of the semiconductor power conversion device of the present invention.

FIG. 5 is a circuit diagram showing a conventional semiconductor power conversion device.

[Explanation of symbols]

 1 Load Current Detection CT 2 Power Supply Voltage Detection PT 3 Control Circuit 4A Inverter Section 4B Inverter Section 4C Inverter Section 4D Inverter Section 4E Inverter Section 5 Semiconductor Power Converter 6A Bandpass Filter 6B Bandpass Filter 6C Bandpass Filter 7B For Boosting Transformer 7C step-up transformer

Claims (1)

[Claims] 1. In a power conversion device including a semiconductor device using a power semiconductor element, a control circuit that calculates an output command value of the power conversion device and an operating frequency range that operates according to the output of the control circuit are different. A semiconductor power conversion device comprising a plurality of semiconductor devices.