JPS5850113B2 - Inverter voltage control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impark voltage control method for reducing output voltage fluctuations caused by sudden changes in the voltage of a DC power source to be converted in a bridge-connected impark that combines a current source impark and a voltage source inverter.

In general, inverters that convert DC electricity into AC electricity are classified into current-type impulse inverters and voltage-type inverters.

These basic circuit configurations are shown in FIGS. 1 and 2.

That is, E is a DC power source to be converted, OR, to CR4 are control rectifying elements, LD is a smoothing reactor, ZL is a load, D is a feedback rectifier, and CD is a smoothing capacitor used as an energy storage element.

However, the current source impark shown in FIG.
It is known that the voltage source inverter shown in the figure itself does not have a voltage control capability, but by using a combination of these in a bridge connection, the inverter itself has a voltage control function.

The bridge-connected inverter constructed in this manner is, for example, as described in Japanese Patent Application Laid-open No. 81935/1982, a current source inverter with a simple circuit configuration and a voltage source inverter that can operate stably regardless of the load. The advantages of this are effectively utilized to make it small and lightweight.

This is shown in FIGS. 3 and 4.

FIG. 3 shows a known example of a bridge-connected impark device, and FIG. 4 shows a control signal and voltage waveform of a control rectifier element with the circuit configuration shown in FIG. 3.

In other words, the device shown in Fig. 3 is constructed by connecting the circuit configurations shown in Figs. 1 and 2 in parallel to the load ZL, and the DC power source E to be converted is connected to the DC input terminal of the current type impark section, and the voltage It is constructed by connecting a smoothing capacitor CD to the DC input terminal of the impark section.

Further, FIG. 4 shows the case where the control rectifiers CR1, OR2 are controlled to advance by an electrical angle θ relative to the control rectifiers OR, 3, OR, .

In the device shown in FIG. 3, the AC output voltage eL is uniquely determined by the control rectifying elements OR3, C, and R, and becomes a rectangular wave whose peak value is the height of the DC voltage D of the smoothing capacitor CD.

Further, the voltage waveform VLD of the smooth riatle LD is as shown in the example.

Furthermore, the control rectifier elements OR, ,C of the current source inverter section
R2 is the control rectifier C of the voltage source inverter section, respectively.
! R3,C! When R4 is controlled with a phase difference of electrical angle θ, the relationship between the input DC voltage E and the DC voltage VD becomes as shown in the following equation.

In this way, the AC output voltage e4. Since is a rectangular AC wave with a peak value of VD, it is determined by the input DC voltage vE and the electrical angle θ which is the control angle, and it can be seen that the voltage can be controlled by the impark itself.

FIG. 5 is a block diagram showing a conventional inverter voltage control method, where pv is an AC output voltage detector, Sv is a voltage setting device,
OOM is a comparator, AMP is an amplifier that amplifies the output of the comparator COM, O20 is an oscillator that serves as a reference for the operation of the voltage source inverter, and G is a control rectifier CR3 that amplifies the output of the oscillator O8C.゜Gate amplifier that gives a pulse signal to the gate of CR4, PS is amplifier AM with reference to oscillator O8C
a phase shifter that generates a phase-shifted signal in response to the signal of P;
■ is a control rectifier CR1 that amplifies the output signal of the phase shifter PS.
+ This is a gate amplifier that provides a pulse signal to the gate of CR2.

In the drawings, the same reference numerals as in FIGS. 1 to 3 indicate the same components.

In the conventional device constructed in this way, the phase shifter PS simply uses the reference value of the voltage setter Sv and the AC output voltage detector Pv.
This method obtains an output for comparison with the output, and due to the delay that inevitably occurs in the voltage control system, it has been impossible to perform control that is responsive to transient fluctuations.

In view of the above-mentioned points, the present invention provides an inverter voltage control method that is sufficiently responsive to sudden changes in the input DC voltage of the current type impark section.

The present invention will be explained below based on the drawings.

FIG. 6 is a block diagram showing an embodiment to which the present invention is applied, and Es is an input DC voltage detector that detects input DC voltage fluctuations and supplies its output signal to the phase shifter PS'.

In the figure, the same reference numerals as in FIG. 5 indicate the same components.

In this way, the circuit shown in FIG. 6 has an input DC voltage detector E8 added to the circuit configuration shown in FIG. 5, and the function of the input DC voltage detector Es is shown in FIG.

In other words, the input DC voltage detector Es acts to generate a signal and outputs the amount of variation in the input DC voltage (E) as shown in the example.

In this embodiment, when the input DC voltage suddenly changes, the amount of change is applied from the input DC voltage detector Es to the phase shifter PS' to control the gate amplifier GI of the current source impark part, and the voltage The firing phase impulse between the type inverter section and the current source inverter section is automatically controlled in the direction of maintaining the AC output voltage at a predetermined value.

Since the control system is performed in an open loop, it is possible to perform coordinated control, and transient voltage fluctuations can be sufficiently suppressed without increasing the number of main circuit components such as the smoothing capacitor CD1 and the smoothing axle LD. .

FIGS. 8 and 9 each show an example of a three-phase impark device to which the present invention is applied.

As shown, the apparatus in FIG. 8 includes a smooth reactor LD1. L.D.
It is composed of current source inverter parts each equipped with a 2°LD3, and the device shown in Fig. 9 has a smoothing reactor L.
D is commonly provided in three sets of current source inverter sections.

It is clear that the voltage control method as shown in FIG. 6 can also be applied to such a three-phase impark device.

As described above, according to the present invention, it is possible to provide a bridge-connected impark voltage control method that is sufficiently responsive to sudden changes in the input DC voltage of the voltage source inverter section.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram for the basic circuit of a conventional current-source impark, Fig. 2 is a wiring diagram for the basic circuit of a conventional voltage-type impark, and Fig. 3 is a wiring diagram for a known example of a bridge-connected inverter device. , FIG. 4 is a time chart shown to explain the circuit operation of FIG. 3, FIG. 5 is a block diagram showing a conventional inverter voltage control method, and FIG. 6 is a block diagram showing an embodiment of the present invention. , FIG. 1 is a diagram showing the function of the input DC voltage detector portion, and FIGS. 8 and 9 are wiring diagrams showing an example of a three-phase impark device to which the present invention is applied. E: DC power supply to be converted, CR1 to CR6, CR
1, ~CR, 6... Control rectifier, D, D
1~D6...Feedback rectifier, LD, LDt~LD
3...Smoothing reactor, cD...Smoothing capacitor, ZL...Load, P■...
AC output voltage detector, Sv... Voltage setting device, C
OM... Comparator, PS, PS'... Phase shifter, Gv. GF...Gate amplifier, Es...Input DC voltage detector.

Claims (1)

[Claims] 1. A current source inverter configured with a smooth sliding axle and a plurality of controlled rectifiers, and an energy storage element connected between a plurality of control rectifiers, a plurality of feedback rectifiers, and a DC terminal. A bridge-connected inverter in which a voltage-type impark is connected in parallel to a load, and the load power is supplied from a converted DC power source connected to a DC input terminal of the current-type impark, and the load voltage of the impark is connected in parallel to the load. is introduced into a voltage control system including a comparator, a phase shifter, and a gate amplifier, respectively, and the load voltage is kept constant by controlling the firing phase of the current source inverter with respect to the voltage source inverter. In the impark voltage control method, an open-loop control system detects a sudden change in voltage of the DC power source to be converted and applies this signal output to the phase shifter. An impark voltage control method characterized by controlling the ignition phase of.