JPS62104481A - Driving system for dc power source - Google Patents

Abstract

PURPOSE:To reduce a surge voltage by superposing drive signals of transistors at a predetermined electric angle between phases, continuing currents to continue a regenerative current, and reducing a DC voltage rise at regenerative time. CONSTITUTION:Power from an AC power source 1 is supplied through a converter 3 and an inverter 4 to an AC induction motor 8. A controller 7 supplies drive signals 5, 6 to the converter 3 and the inverter 4, respectively. The drive signals 5 of transistors CTR1-CTR6 on the converter 3 are widened more than a zone 120 deg. (electric angle) that rectifiers D1-D6 are conducted from the phase slightly ahead of 30 deg. electric angle to the phase slightly behind 150 deg. electric angle width the phase voltage of the power source 1 as a reference, and the zone that the adjacent phases are superposed is provided.

Description

[Detailed description of the invention] [Industrial application field].

The present invention provides a direct current Tr! that enables regeneration by bridge-connecting an arm consisting of a self-extinguishing semiconductor switching element connected in antiparallel to a rectifier. , regarding Gensozu.

[Prior Art] Figure 3 is a diagram showing the configuration of a conventional DC power supply of this type (
(However, an inverter and an AC induction motor are also shown.) FIG. 4 is a diagram showing the direction of current in the rectifier power supply section 3 in FIG.
It is a time chart showing the relationship among the conduction sections of the rectifiers D1 to D6, the AC power supply, the drive signals of the transistors CTRI to CTR8, and the waveform of the regenerative current Ioc in the DC power supply device shown in the figure.

In this DC power supply, in the electric mode, the rectifiers D1 to D6 of the converter 3 conduct, and current flows in the direction of the solid line in FIG.
etc.), and in the regeneration mode, the control circuit 7 is synchronized with the AC power source 1, and the control circuit 7
Transistors CTRI - CTR (
(By driving the
A lit current flows (this is called a regenerative current Ipc), and an operation is performed to regenerate the energy of the load to the AC power supply l.

[Point to be solved by the invention 1 Conventionally, these regeneration transistors CTR1 to CTR
As shown in Fig. 5, the drive signal 5 of No. 8 has a gap Td between each phase for the purpose of preventing line-to-line short circuit mode and preventing an increase in circulating current, so the waveform of the regenerative current Ioc is zero current. It was a continuous waveform that always had a section of . Note that Tp is the pulse width of the drive signal 5, and the gap Td
The relationship 'rp=eo° (electrical angle) - 2XTd holds true.

For this reason, conventional DC power supplies have the following drawbacks.

(2) The peak value of the current is larger than the average value of the regenerative current Ioc.

■Since the current peak value is when the transistors CTRI to CTR6 turn off, the voltage at turn-off is large, and therefore the current applied to the transistors CTRI to CTR6 is intermittent as shown in Figure 5. The rise in the DC voltage increases. This DC voltage -
1- Ascending is power transformer, line and AC reactor 2
It is easily influenced by the inductance of transistors CTRI to CTR8 (reverse bias A
SO), it is necessary to reduce the capacity of the device.

■Furthermore, the gap Td is between all transistors CTR1-CT
This is the section in which R8 is turned off, and in this section, +li source distortion occurs, which adversely affects other devices.

[Means for Solving Problems 1] The drive method of the DC power supply device of the present invention is such that the transistor drive signal is changed from a phase slightly ahead of 30 degrees in electrical angle to 150 degrees in electrical angle with respect to the phase voltage of the alternating input power source. It is characterized by providing a width of 120 degrees or more in electrical angle to a slightly delayed phase, and providing an overlapping section with an adjacent phase.

[Operation] Therefore, the regenerative current is continuous, the DC voltage rise during regeneration is reduced, and the surge voltage is also reduced.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a time chart showing an embodiment of the driving method of the DC power supply device of the present invention. Note that the DC power supply is
Refers to what is shown in the figure.

In this embodiment, transistors CTRI~
By making the drive signal 5 of the CTR 8 wider than the 120° (electrical angle) conduction section of the rectifiers D1 to D6, and overlapping the conduction sections of each phase as shown in the diagonal line (a in the figure is the drive signal of the previous phase). b is the electrical angle of overlap with the drive signal of the subsequent phase), creating a commutation mode performed by the thyristor and making the current continuous (regenerative current 1o in Figure 1).
(See waveform in c).

In this case, the pulse width Tp of the drive current 5 is 'rp =
120° (electrical angle) + a' (electrical angle) + b0 (electrical angle)≧120° (electrical angle).

In the overlapping section, a mutual short circuit occurs, and a short circuit current that is suppressed by the inductance of the power supply and wiring and the AC reactor 2 flows, but unlike a cysostar, a transistor does not have a reverse blocking ability, so it is necessary to Turn off the drive signal and short circuit section (electrical angle a0, bo section)
It is necessary to make it as small as possible. In this example, this is changed to 1°
~2° (electrical angle).

[Effects of the Invention] As explained above, the present invention is superior to the conventional method when obtaining the same regenerative DC Ichihara (average value) by overlapping transistor drive signals between each phase and making the '1i current continuous. The comparison has the following effects:

■The peak value of the current waveform is small. ■The current when the transistor is turned off is small, and the surge voltage generated when the transistor is turned off is also small (see Figure 2). ■The DC voltage rise during regeneration is small (the (See Figure 2), etc., it is possible to increase the margin compared to transistors, increasing the margin of the device and improving reliability.

■Also, power supply distortion used to occur twice, but
This occurs only once, and the drop-off is reduced to about half of the conventional level due to a short circuit between the lines.

[Brief explanation of drawings]

FIG. 1 is a time chart showing the waveforms of the drive current 5 of the transistors CTRI to CTR6 and the regenerative type f & T o C in an embodiment of the drive method of the power supply device of the present invention;
The figure shows a comparison of the characteristics of DC voltage and surge voltage with respect to DC current between the present invention and the conventional system. Figure 3 is a diagram showing the configuration of a regenerative DC power supply. Figure 4 is the same as that of Figure 3. A diagram showing the direction of current in the converter 3 in the electric mode and in the regeneration mode. FIG. 5 shows the drive signals 5 of the transistors CTRI to CTRfi in the regenerative DC power supply device of FIG.
, is a diagram showing the waveform of regenerative current Ipc. ■...AC power supply, 2...AC reactor, 3...Converter, 4...Inverter, 5...Transistor CTRI of converter 3 ~CTR13 drive signal 6... Inverter 4 transistor drive signal 7... Control circuit, 8... AC induction machine, old ~D6... Rectifier , CTRI~CTR8...Transistor, Ioc
...Regenerative current.

Claims (1)

[Claims] In a DC power supply device that enables regeneration by bridge-connecting an arm consisting of a self-extinguishing semiconductor switching element connected in antiparallel to a rectifier, the transistor drive signal is set at an electrical angle of 30° with respect to the phase voltage of the AC input power supply. A drive system for a DC power supply device characterized by providing a width of 120° or more in electrical angle from a slightly leading phase to a slightly lagging phase of 150° in electrical angle, and providing an overlapping section with adjacent phases.