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Neutral point voltage controller

A neutral point voltage and control device technology, which is applied in the direction of output power conversion devices, electrical components, irreversible DC power input to AC power output, etc., can solve the problem of expensive neutral point voltage control devices and are susceptible to noise and other issues to achieve the effect of reducing impact and improving reliability

Inactive Publication Date: 2009-03-04
YASKAWA DENKI KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0021] However, since this isolation amplifier 6 is analog and has an expensive insulation circuit with wide linear characteristics, there is a problem that the neutral point voltage control device is expensive.
In addition, in the conventional neutral point voltage control device, since the calculation circuit 3 performs neutral point voltage control based on an analog signal, there is a problem that it is easily affected by noise, etc.

Method used

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Embodiment 1

[0040] A three-phase neutral point clamp type PWM inverter device according to Embodiment 1 of the present invention will be described with reference to FIG. 7 . FIG. 7 is a block diagram showing the configuration of a PWM pulse calculator applied to the three-phase neutral point clamp type PWM inverter device of this embodiment. As shown in Figure 7, the three-phase neutral point clamped PWM inverter device of this embodiment has a parameter calculator 101 for neutral point potential control, a vector time calculator 102, a vector time register 103, and a PWM mode setting device 104.

[0041] In the case of the three-phase neutral-point clamped PWM inverter device of this embodiment outputting the output voltage vector V, according to Figure 4 The shown vectors constitute the region (regions 1 to 6) in which the output voltage vector V exists, and output PWM pulses. Assume the classification of the vectors that make up the regions as Figure 4 As shown, the vector time ca...

Embodiment 2

[0114] The second neutral point voltage control device of the present invention will be described. FIG. 8 is a block diagram showing the structure of the neutral point voltage control device of this embodiment. As shown in FIG. 8 , the neutral point voltage control device of this embodiment is composed of a subtractor 1 , two comparators 2 , a calculation circuit 3 and an isolation circuit 10 .

[0115] Subtractor 1 output from the neutral point voltage V CN subtract the first reference voltage V ref1 value. The first reference voltage value V ref1 is a half voltage value (1 / 2·V PN ).

[0116] In addition to the first reference voltage value V ref1 In addition, a second reference voltage value V ref2 and the third reference voltage V ref3 . The second reference voltage value V ref2 and the third reference electric value V ref3 like Figure 9 Shown are negative and positive values, respectively.

[0117] A comparator 2 where the output value of the subtractor 1 is ...

Embodiment 3

[0124] Next, a neutral point voltage control device according to Embodiment 3 of the present invention will be described with reference to FIG. 10 . Fig. 10 is a block diagram showing the configuration of a neutral point voltage control device according to Embodiment 3 of the present invention. As shown in FIG. 10, the difference between the neutral point voltage control device of this embodiment and the neutral point voltage control device of the above-mentioned embodiment is that a comparator 4 is provided instead of two comparators 2, and a storage device 5 is provided instead of two comparators 2. Calculation circuit 3.

[0125] Comparator 4 input from the neutral point voltage V CN subtract the first reference voltage V ref1 value, the output value of the subtractor 1 is more than the second reference voltage value V ref2 Small case, in the second reference voltage value V ref2 Above the third reference voltage value V ref3 In the following cases, the ratio of the th...

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Abstract

The invention provides a neutral voltage controller for controlling a neutral voltage, i.e. a voltage beween a neutral point between two capacitors connected in series between a positive point and a negative point of a three levels converter, and the negative point, characterised in that it comprises: A subtractor which outputs a value obtained by subtracting a first reference voltage, a voltage value equal to 1 / 2 the voltage between positive point and negative point from a neutral voltage. A first comparator which turns on a signal for increasing the neutral voltage when the value of output of the subtractor is lower than the value of a second reference voltage. A second comparator which turns on a signal for reducing the neutral voltage when the value of output of the subtractor is higher than the value of a third reference voltage. An insulation circuit convertes the signals outputted from the two comparators into a two-bit digital signal. And an calculating circuit for calculating the neutral voltage control command based on the digital signal and outputting.

Description

[0001] This application is filed in accordance with Article 42 of the Detailed Rules for the Implementation of the Patent Law. The date of application is November 30, 2001, and the application number is 01820178. A divisional application of the Chinese patent application for "neutral point voltage control device". technical field [0002] The present invention relates to power conversion devices such as inverters and servo drives for variable-speed drive motors, three-level neutral point clamp type PWM (pulse width modulation) inverter devices as one of the power conversion devices of connection systems, and The voltage between the neutral point and the negative bus, which is the neutral point, is used in this three-level neutral-point clamped PWM inverter device to control the two capacitors connected in series between the positive bus and the negative bus. Voltage neutral point voltage control device. Background technique [0003] figure 1 It is a circuit diagram showing...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/487H02M7/48H02M7/483
Inventor 田中善之山中克利渡辺英司
Owner YASKAWA DENKI KK
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