Pulse width modulation converter

Details Pulse width modulation converter Pulse width modulation converter

1999-06-25

2000-08-22

Han, Jessica

Electric power conversion systems

Current conversion

With means to introduce or eliminate frequency components

363 37, 323207, H02M 112

Patent

active

06108221&

DESCRIPTION:

BRIEF SUMMARY
TECHNOLOGICAL FIELD

The present invention relates to a pulse width modulation converter (referred to as "PWM converter" hereinafter), in particular to a PWM converter for converting three-phase AC power to DC power.


BACKGROUND ART

In recent years, PWM converters have been widely used with an object of transmitting and receiving electric power in both directions from an AC power source to a DC power source or from a DC power source to an AC power source.
PWM converters are also often used with an object of reducing a phase difference of voltage and current of an AC power source, i.e., for the purpose of improving a power factor, and suppressing current distortion of an AC power source, i.e., reducing higher harmonics of the power source.
A typical conventional PWM converter system will now be described with reference to FIGS. 14 to 17.
In FIG. 14, it is assumed that a voltage between a plus terminal and a minus terminal of a smoothing capacitor 60 is higher than the maximum value of a phase voltage of a three-phase AC power source 1. First of all, in a current instruction generator 7, a phase information value .theta. and amplitude instruction value ip of the three-phase AC current wave form to be supplied from the three-phase AC power source 1 are set, and on the basis of these values of information, the current instruction generator 7 generates respective line current instructions that are to be input from the three-phase AC power source 1: these are first line current instruction iTU, second line current instruction iTV, and third line current instruction iTW.
Next, a power source current detector 9 detects two line currents of the three line currents output from the three-phase AC power source 1 and the remaining one line current is then obtained by taking the sum of the two detected line currents and inverting the sign thereof, and the obtained three line currents are output as the first line current measurement result iFU, second line current measurement result iFV, and third line current measurement result iFW. It should be noted here that this power source current detector 9 may be also constructed to detect the three line currents of the three-phase AC power source 1, outputting these as first line current measurement result iFU, second line current measurement result iFV and third line current measurement result iFW.
Next, a current controller 106 receives these first line current instruction iTU, second line current instruction iTV, third line current instruction iTW, and first line current measurement result iFU, second line current measurement result iFV, and third line current measurement result iFW to be compared, respectively, and generates a first switching instruction signal PU, second switching instruction signal PV, and third switching instruction signal PW controlling such that, the first line current instruction iTU and first line current measurement result iFU, the second line current instruction iTV and second line current measurement result iFV, and the third line current instruction iTW and third line current measurement result iFW are respectively coincident with each other as closely as possible.
Next, a main circuit power control section 8 includes the smoothing capacitor 60 and a switching power device group having a three-phase bridge construction. The switching power device group is comprised of a first switching power device Q1 connected to the plus terminal of the smoothing capacitor 60 for controlling the first line current IU, second switching power device Q2 connected to the plus terminal of the smoothing capacitor 60 for controlling the second line current IV, third switching power device Q3 connected to the plus terminal of the smoothing capacitor 60 for controlling the third line current IW, fourth switching power device Q4 connected to the minus terminal of the smoothing capacitor 60 for supplying the first line current IU to the three-phase AC power source 1, fifth switching power device Q5 connected to the minus terminal of the smoothing capacitor 60 for contro

REFERENCES:
patent: 5045991 (1991-09-01), Dhyanchand et al.
patent: 5491624 (1996-02-01), Levran et al.
patent: 5621627 (1997-04-01), Krawchuk et al.
Jiang, Y. et al.: "Simple High Performance Three-Phase Boost Rectifiers", Proceedings of the Annual Power Electronics Specialists Conference, Taipei, Taiwan, Jun. 20-24, 1994, vol. vol. 2, No. Conf. 25, Jun. 20, 1994, Society, pp. 1158-1163, XP000510342, see Figure 2.

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