JPH03230753A - Controlling method for converter - Google Patents

Abstract

PURPOSE:To improve the power factor of input by resetting the current of a chock coil with every switching, and driving the switching elements with fixed frequency, and controlling the on time according to the change of output voltage. CONSTITUTION:A series circuit, comprising a switching element 4, a choke coil 6, and a switching element 5, is connected between the DC output terminals of a full-wave rectifying circuit 2. By driving circuits 18 and 19, the switching elements 4 and 5 are turned on or turned off at the same time with the fixed frequency enough high than the frequency of AC voltage. The on-time is controlled according to the change of output voltage. The current of the choke coil 6 is reset with every switching. The AC gain of an error amplifier 15 is let down enough with a capacitor 20 and a resistance 21 so that it may not respond to the basic frequency of full-wave rectifying voltage. This way, input current waveform becomes analog to the input voltage waveform.

Description

[Detailed description of the invention] [Not for industrial use! f] The present invention relates to a converter that rectifies and smoothes AC voltage and converts it into DC voltage, and relates to a method of controlling the converter to make the input terminal waveform similar to the input terminal waveform.

[Conventional technology]

8 and 9 are diagrams for explaining the 'M m method of the conventional converter, where FIG. 8 shows a circuit diagram and FIG. 9 shows an operating waveform diagram.

In Fig. 8, an AC voltage is passed through a high-frequency filter I in a full-wave U flow circuit 2, and a switching element 4.5 of a circuit 3 is switched at a frequency sufficiently higher than the frequency of the AC voltage. By letting Chikofupa times 1I
Direct fLf to the output of II3! Get pressure.

The operation of the chip-flange circuit 3 shown in FIG. 8 will be explained with reference to the operating waveform diagram shown in FIG. 9. First, when switching elements 4.5 are turned on at the same time, energy is stored in choke coil 6, and electric current IILIt (
181 in FIG. 9) and the electric current filz (shown in FIG. 9 181) flowing through the switching element 4.5, the inductance of the choke coil 6 is L total'eL? Assuming that the voltage full-wave rectified by the iW current circuit 2 is E (shown at 181 in FIG. 9), it rises with a slope of E/L. Next, when the switching elements 4 and 5 are turned off at the same time, the energy stored in the choke coil 6 causes electricity to flow through the rectifier diode 7 and the flyboil diode 8! (Chiraak coil 6
The fa current flowing through the v1 diode 7 is shown in FIG. 9, 1b+, and the fIi current 2. A ninth current (shown as idl) flows, charges a large capacitance smoothing capacitor 9, and obtains a DC output voltage E0 from this capacitor 9.

The current detection value is obtained by detecting the current 11 flowing through the choke coil 6 at a variable *mlO and extracting its low frequency component. :,
Output i pressure +>, and base I'Frri pressure E1. ．． The error amplifier 11 detects and amplifies the deviation between
) 12 is amplified by the differential amplifier 13, and the pulse width control circuit 14 drives the switching element 4.5 by 14g1 so that the output thereof is minimized.

By setting the voltage to 1 Am in this way, the Ai of the choke coil 6 makes the Ura waveform (shown in FIG. 9 1b+) similar to the full-wave rectified voltage waveform (shown in FIG. 9 181), and the input terminal Ai
Reduces harmonic components.

[Invention tries to solve! l! However, in the Ml)1 method, the current waveform of the choke coil is made similar to the full-wave rectified voltage waveform, so harmonics can be reduced compared to a capacitor input type rectifier circuit, but the input current waveform is The waveform will no longer be similar to the input terminal waveform. This is because in order to make the input current waveform similar to the input voltage waveform, the duty ratio of the switching element must be constant regardless of the voltage phase.
If the current of the chiller coil is a sine wave as shown in 1.

The duty ratio of the switching element is controlled by the voltage phase (ML
Because it becomes necessary. As a result, there is a drawback that the input power factor deteriorates. Another problem is that VCA is expensive and requires offset yi adjustment. Furthermore, a special current transformer is required to measure direct current.

[Means to solve the problem]

In order to eliminate the above-mentioned drawbacks, the present invention provides a full-wave rectifier circuit that full-wave rectifies an AC voltage to obtain a full-wave rectified voltage, and a full-wave rectifier circuit that is connected to the output of the full-wave rectifier circuit and has a conversion frequency sufficiently higher than the AC voltage The switching element includes two switching elements that are simultaneously turned on and off at Ni1, a choke coil sandwiched between the switching elements, two diodes connected to both ends of the choke coil, and a smoothing capacitor. In the v40+1 method of a converter, which stores energy in the choke coil when it is on, and outputs energy to the smoothing capacitor via the two diodes when it is off, and supplies power from both ends of the capacitor to the load, the current in the chiller coil At the same time, the switching element is driven at a fixed frequency, and the on-time is set to 14 times according to fluctuations in the output voltage.
14FB method of converter characterized by rR,
and a full-wave rectifier circuit that obtains a full-wave rectified voltage by full-wave rectifying an AC voltage, a transformer in which a primary 5IIIA is connected to the output of the full-wave rectifier circuit, and a primary winding of the transformer and the full-wave rectifier circuit. A switching element connected between the outputs of the rectifier circuit and controlled to be turned on and off at a conversion frequency sufficiently higher than the alternating current voltage, and a series circuit of a diode and a smoothing capacitor connected to the secondary winding of the transformer, When the switching element is turned on, energy is stored in the primary S6 of the transformer, and when the switching element is turned off, energy is released from the secondary winding of the transformer to the smoothing capacitor via the diode,
In the t14 control method of the converter that supplies power from both ends of the capacitor to the load, the current in the primary winding of the transformer is reset every time the transformer is switched, and the switching element is driven at a fixed frequency to compensate for fluctuations in the output voltage. Turn on time accordingly! This invention provides a 111g11 method for a converter characterized by i-control.

(Function) According to method [6] of such a converter, the input current waveform can be made similar to the input terminal waveform, so that it becomes as if a resistor is connected to the input terminal, and the input power factor can be improved.

〔Example〕

1 and 2 are for explaining one embodiment of the present invention, FIG. 1 shows a circuit diagram, and FIG. 2 shows an operation waveform diagram.

In FIG. 1, an AC voltage is connected to the input terminal of a full-wave rectifier circuit 2 through a high-frequency filter 1, and a switching circuit 4. Chilark coil6. A series circuit of switching elements 5 is connected. Then, a series circuit of a rectifier diode 7 and a smoothing capacitor 9 is connected in parallel with the switching wife and child 5, and between the connection point between the switching element 4 and the chiroku coil 6 and the connection point between the switching wife and child 5 and the smoothing capacitor 9. A flywheel diode 8 is connected in the direction in which it conducts when the switching wife 45 is off, the output is taken out between the terminals of the smoothing capacitor 9, and the output voltage is stabilized by 14 m.
In the W4 difference amplifier circuit 15, the output voltage E0 is connected to the resistor 1.
6.17, the 1% difference with the reference voltage E
, 5 are turned on and off.

Next, the operation will be explained. If the voltage at any phase of the full-wave rectified voltage is E, then the current () flowing when the switching elements 4.5 are simultaneously turned on is, and if the inductance of the choke coil 6 is L.

1.=Et/L, and if the on time t is constant and the current of the chiller coil is reset at each switching, the current 1. The line connecting the peak values of , as shown in 21iJfbl, becomes similar to the waveform of the full-wave rectified voltage shown in FIG. 2ial.

If the switching elements 4 and 5 are driven at a switching frequency that is sufficiently high compared to the frequency of the AC voltage and the current of the chiller coil 6 is reset at each switching, the output current of the full-wave rectifier circuit 2 is changed to the switching wife and child 4 at each switching.
．． The average value of the current I2 flowing through the current I2 is continuous. The average value l□ for each switching is assumed to be the switching period T and the on time Ton.

As mentioned above, ET, , /L are similar to the full-wave rectified voltage waveform, so if Ton/T is kept constant, the output current of the full-wave rectifier circuit will be similar to the full-wave rectified voltage waveform, and therefore ,
The input current waveform becomes similar to the input voltage waveform.

Since all the current flowing to the human power flows to the output, the voltage of the smoothing capacitor 9 fluctuates at the fundamental frequency of the full-wave rectified voltage E. If the output voltage stabilization control has a gain with respect to the fundamental frequency of the full-wave rectified voltage E, switching! The child's off time will be reduced to mm. , , /T changes, and the input terminal waveform does not have a similar shape to the voltage waveform. Therefore, the AC gain of the 111Z error amplification circuit 15 is adjusted by the capacitor 20 and the resistor 21.
The input terminal waveform becomes similar to the voltage waveform by sufficiently lowering the voltage E, so as not to respond to the fundamental frequency of the full-wave rectified voltage E, and by making stabilization control possible only for direct current.

FIG. 3 is a diagram for explaining another embodiment of the present invention, in which a bandpass filter 22 is inserted in the output voltage detection section of the circuit of FIG. 1, and the fundamental frequency component of the full-wave rectified voltage E is After removing it, r! Difference amplifier! 1 is manually operated, and is designed to improve response to load fluctuations and input fluctuations.

FIG. 1114 is a diagram for explaining another embodiment of the present invention, in which a high-speed response converter circuit 23 is connected to the output section of the circuit shown in FIG. In the embodiment shown in FIG. 1, the response is slow, and in the embodiment shown in FIG.
When input/output insulation is required, the system is configured to perform stabilization i4m at high speed, insulate input/output, and supply power with high voltage accuracy to the load. Incidentally, since this converter circuit 1!823 is well known, a description of its operation will be omitted. Furthermore, although a forward converter is shown in this embodiment, similar effects can be obtained with any circuit configuration such as a flyback converter.

FIG. 5 is a diagram for explaining another embodiment of the present invention, in which a flyback type circuit is used instead of the 1,170-pin circuit shown in FIG. Used in certain cases.

In FIG. 5, the AC voltage is connected to the input terminal of the full-wave rectifier circuit 2 via the high-frequency filter l, and the primary winding mNl of the transformer 24 and the switching terminal are connected between the DC output terminals of the full-wave rectifier circuit 2. Connect the series circuit of element 4. Then, a series circuit of a rectifier diode 7 and a smoothing capacitor 9 is connected to the secondary S latitude N2 of the transformer 24, and the output is taken out between the terminals of the smoothing capacitor 9, and the output voltage is stabilized! 4 people are lI! In the I difference amplifier circuit 15, the output voltage E, is divided by the resistor 1617, and the base Ijfli pressure E,...
, is amplified by the error amplification 311, and the photocoupler 2
In this embodiment, the pulse width is insulated by 5, and the pulse width 1A is transmitted to g314, and after converting the pulse width, it is sent to the drive circuit 18 and the switching element 4 is turned on and off. The operation is almost the same as that described in the embodiment of FIG. 1, and the same effects can be obtained.

FIG. 6 is a diagram for explaining another embodiment of the present invention, in which an Indian pass filter 22 is inserted into the output voltage detection section of the circuit of FIG. 5, and the fundamental frequency component of the full-wave rectified voltage E is is removed and then manually applied to the a-difference amplifier 11, with the aim of improving the response to load fluctuations and input fluctuations.

FIG. 7 is a diagram for explaining another embodiment of the present invention, in which a high-speed response chip zipper circuit 26 is connected to the output section of the circuit of FIG.
is connected. In the embodiment shown in Fig. 5, the response is slow, and even in the embodiment shown in Fig. 5, there is voltage pulsation in the fundamental frequency component of the full-wave rectified voltage, which causes a problem with the load. 4 control, and is configured to supply power with high voltage accuracy to the load. Incidentally, since this chipper circuit 26 is well known, a description of its operation will be omitted.

〔Effect of the invention〕

As explained above, the present invention does not use any special circuit such as the current detection function fLS or VCA for current waveform control, and has a simple configuration that allows the input current waveform to be similar to the input voltage waveform. It is possible to change the input power factor by making it appear as if a resistor is connected to the input terminal.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining one embodiment of the present invention, FIGS. 3 to 7 are diagrams for explaining one embodiment of the present invention, respectively, and FIGS. 8 and 9 are diagrams for explaining one embodiment of the present invention, respectively. FIG. 2 is a diagram for explaining a conventional example. l...High frequency filter 2...Full wave rectifier circuit 3.
・・Chi1 Fupa circuit 4.5・・Switching diode 6・・Chiku-ku coil 7・・Rectifier diode 8・・Flywheel diode 9・・Smoothing capacitor 10・・Current transformer Vessel II...
・Error amplification B 12...VCA13...Differential amplification 2514...Pulse width control circuit 15...Error amplification circuit 16.17...Resistors 18, 19...Drive circuit 20...Capacitor 21...Resistance 22
... Bandpass filter 23 ... High-speed response converter circuit 24 ... -Transformer 25 ... Photocoupler 26 ... High-speed response chipper circuit

Claims (3)

[Claims] (1) A full-wave rectifier circuit that full-wave rectifies an AC voltage to obtain a full-wave rectified voltage; and 2, which is connected to the output of the full-wave rectifier circuit and is simultaneously controlled on and off at a conversion frequency sufficiently higher than the AC voltage. The device includes two switching elements, a choke coil sandwiched between the switching elements, two diodes connected to both ends of the choke coil, and a smoothing capacitor, and stores energy in the choke coil when the switching element is turned on. , in a method of controlling a converter that releases energy to the smoothing capacitor through the two diodes when off and supplies power to the load from both ends of the capacitor, the current of the choke coil being reset each time the choke coil is switched; A method for controlling a converter, characterized in that the switching element is driven at a fixed frequency and the on-time is controlled according to fluctuations in output voltage. (2) A full-wave rectifier circuit that full-wave rectifies an AC voltage to obtain a full-wave rectified voltage, a transformer with a primary winding connected to the output of the full-wave rectifier circuit, and a primary winding of the transformer. a switching element connected between the outputs of the full-wave rectifier circuit and controlled to turn on and off at a conversion frequency sufficiently higher than the AC voltage; and a series circuit of a diode and a smoothing capacitor connected to the secondary winding of the transformer. storing energy in the primary winding of the transformer when the switching element is turned on;
In a method for controlling a converter, which releases energy from the secondary winding of the transformer to the smoothing capacitor via the diode when turned off, and supplies power to the load from both ends of the capacitor, the primary winding of the transformer A method for controlling a converter, characterized in that the current is reset every time the current is switched, the switching element is driven at a fixed frequency, and the on-time is controlled according to fluctuations in the output voltage. (3) The method of controlling a converter according to claim 1 or 2, wherein the on-time of the switching element is made not to respond to the fundamental frequency of the full-wave rectified voltage.