JPH03230760A - Controlling method for converter - Google Patents

Abstract

PURPOSE:To improve the power factor of input by resetting the current of a choke coil with every switching, and approximately inversely proportioning the on time of a switching element to the effective value of input voltage, and approximately proportioning the off time to output voltage. CONSTITUTION:A chopper circuit 3 consists of a series circuit comprising switching elements 4 and 5 and a choke coil 6. The switching elements 4 and 5 are turned on or turned off at the same time through driving circuits 20 and 21 by the signal of a pulse width control circuit 14. The switching frequency is made enough higher than that of AC voltage, and the current of the choke coil 6 is reset with every switching. When switching cycle is defined as T and on time as TON, TON/T is made constant to made input current waveform analog to the input voltage waveform. Moreover, the stabilization of output voltage is performed by controlling the off time.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides AC voltage S! In a converter that converts current to DC voltage by smoothing it, a converter that makes the input current waveform similar to the input voltage waveform! 401 method.

[Conventional technology]

8 and 9 are diagrams for explaining a conventional i4 control method of a converter, and FIG. 8 is a circuit diagram.

g%9 Figure shows an operating waveform diagram.

In FIG. 8, an AC voltage is passed through a high-frequency filter l to a full-wave rectifier circuit 2 with a full-wave i! By switching the switching f-elements 4 and 5 of the chiasova circuit 3 at a frequency sufficiently higher than the frequency of the AC tATs pressure, a DC voltage is obtained at the output of the chimapper circuit 3.

The operation of the chip 5 circuit 3 shown in FIG. 8 will be explained with reference to the operation waveform diagram shown in FIG. 9. First, when the switching elements 4.5 are turned on at the same time, energy is blindly loaded in the Chi-Lake coil 6, and the electric current flowing through the Chi-Lake coil 6 is +5! ! L (9th
Figure (shown in bl) and Swift + Y Gui 4.5 1fE
If the electric current tlL[z (shown in m911+a) is the inductance of the choke coil 6, and the voltage full-wave rectified by the full-wave rectifier circuit 2 is E (shown in FIG. 9+a+), then E/L is Then, when the switching elements 4.5 are turned off at the same time, the energy accumulated in the chibuk coil 6 causes a current to flow through the rectifier diode 7 and the flywheel diode 8 (chibuk coil 6
Electricity flowing through! ++ is shown in FIG. 9 ibl, and the current flowing through the rectifier diode 7 is shown in FIG. 9(d)), charging the smoothing capacitor 9 with a large capacity.

A DC output voltage E0 is obtained from this capacitor 9.

The error amplification 5 calculates the deviation between the current II flowing through the 100-1 coil 6 by the converter fL converter IO and extracting its low frequency component, and the output voltage E0 and the reference voltage E r*f.
The difference between the proportional value of the full-wave rectified AC voltage waveform detected and amplified by 11 and the voltage detection value obtained by calculating the voltage MrB type gain amplifier S (hereinafter referred to as vCA) 12 is calculated using a differential J-scaler. 13
The pulse amplitude control circuit 14 controls the driving of the switching element 4.5 at 1A so that the output thereof is minimized.

By controlling tA in this way, the current waveform of the choke coil 6 (shown in FIG. 9 fbl) is changed to the full-wave a current voltage waveform (
9th Mf8+) to reduce harmonic components of the input voltage.

Problem to be solved by the invention] However, in this f1111+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. , the input current waveform is no longer similar to the input voltage waveform. This is because, in order to make the input voltage waveform similar to the input voltage waveform, the duty ratio of the switching element must be constant regardless of the phase of the voltage f, but as in this example, the current of the choke coil must be Assuming it is a sine wave.

This is because the duty ratio of the switching element must be controlled by the voltage phase. As a result, there is a drawback that the input power factor deteriorates. Another problem is that the VCA is expensive and requires offset III adjustment. Furthermore, a special current transformer is required to measure direct current.

(Means for Solving Problem R) In order to eliminate the above-mentioned drawbacks, the present invention provides a full-wave rectifier circuit that performs full-wave rectification of AC voltage to obtain a full-wave rectified voltage, and a 1s full-wave single-current circuit. Two switching elements connected to the output and turned on and off WJ4rII at the same time at a conversion frequency sufficiently higher than the above AC voltage, a choke coil sandwiched between the switching elements, and two diodes connected to both ends of the choke coil. , and a smoothing capacitor, the energy is transferred to the choke coil when the switching element is on, and is transmitted through the two diodes when the switching element is off.
C In the t1011 method of the converter that releases energy to the above-mentioned Hiranamekawa capacitor and supplies power from the l1ii end of the capacitor to the g1 load, the current of the choke coil is reset every time the choke coil is switched, and the on-time of the switching element is A converter characterized in that the predetermined time period is approximately inversely proportional to the effective value or average value of the input voltage, and the off time is set to the predetermined time period approximately proportional to the output voltage! 4 control methods, a full-wave rectifier circuit that obtains a full-wave rectified voltage by fully rectifying an AC voltage, a transformer in which an 11JC winding is connected to the output of the full-frL rectifier circuit, and a primary winding of the transformer. A switching element connected between the line and the output of the 1-2 full 1jL rectifier circuit and turned on and off at a conversion frequency sufficiently higher than the above AC fL voltage, and 2 of the above transformer.
A series circuit of a diode and a smoothing capacitor connected to the next winding is provided, and when the switching element is turned on, the transformer ! In a method for controlling a converter, the converter supplies energy to a secondary winding, releases energy from the secondary S1 of the transformer to the smoothing capacitor via the diode when off, and supplies power from both ends of the capacitor to the load, The current in the primary winding of the transformer is reset at each switching, the on time of the switching element is set to a predetermined time approximately inversely proportional to the effective value or average voltage of the input voltage, and the off time is set to a predetermined time approximately proportional to the output voltage. It also provides a 14r11 method of converter characterized by the time.

(Operation) According to the 11g1 method of such a converter, the input current waveform can be made similar to the input voltage waveform, so that it is as if a resistor is connected to the input voltage, and the input power factor can be improved.

〔Example〕

FIGS. 1 and 2 are diagrams for explaining one embodiment of the present invention, with FIG. 1 showing a circuit diagram and FIG. ff12 showing an operation waveform diagram.

In FIG. 1, an AC voltage is connected to the input voltage of a full-wave rectifier circuit 2 via a high-frequency filter 1, and the full-wave rectifier circuit 2
A switching element 4 is connected between the DC output voltages of 4 and 4. A series circuit of the cheer coil 6 and the switching element 5 is connected. Then, a series circuit of a rectifier diode 7 and a smoothing capacitor 9 is connected in parallel with the switching element 5, and a connection point between the switching element 4 and the check coil 6 is connected to the switching element 5 and the smoothing capacitor 9. A flywheel diode 8 is connected between the points in a direction in which it conducts when the switching f-terminal 4.5 is off, and an output is taken out from between the voltages of the smoothing capacitor 9. And output voltage stabilization M1m
The on-time generating circuit 15 generates a time that is almost inversely proportional to the effective value of the input voltage, the output voltage E0 is divided by the resistor 17.18 in the error amplifier circuit 16, and the reference voltage E r
The off time generation circuit 11819 generates a time approximately proportional to the error voltage obtained by amplifying the 1% difference with m f by the error amplifier 11, and sends these times to the drive circuit 20.21 to drive the switching element 45 on and off. Do by doing.

Next, the operation will be explained. If the voltage value 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 1, and if the inductance value of the check coil 6 is L, then it becomes 1, = Et/L. , the on-time [ is constant and the current of the cheer coil is reset every switching, the line connecting the peak value of the current 1□ will be the full wave shown in Fig. 2 181 as shown in Fig. 2 1b+. The waveform becomes similar to the rectified voltage waveform.

If the switching element 4.5 is driven at a switching frequency that is sufficiently high compared to the frequency of the AC voltage, and the current in the cheer coil 6 is reset at each switching, the output current of the full-wave rectifier circuit 2 is changed to the switching element 4 at each switching.
．． This is a series of average values of the fl current flowing through 5. The average value i, W for each switching is the switching period T,
Let the on time be 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.

On the other hand, if the on-time of switching element 4.5 is always kept constant, the current peak value changes in proportion to the effective value of the input voltage. When set, fl at maximum input voltage
The current peak value is large (too much). Therefore, by making the on time almost inversely proportional to the input voltage, the current peak value can be kept almost constant regardless of the input voltage.The output voltage can be stabilized by controlling the off time. To/T is kept constant by keeping the off time unchanged if the load power does not change.

Since all the current flowing to the input 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 i4 control has a gain with respect to the fundamental frequency of the full-wave GL current voltage E, the off-time of the switching element is controlled in order to reduce fluctuations in this frequency component, and T , , /T changes and the input current waveform does not have a similar shape to the voltage waveform, so the error amplifier I! of FIG. ! By sufficiently lowering the AC gain of 316 with the capacitor 22 and resistor 23 so that it does not respond to the fundamental frequency of the full-wave rectified voltage E, and making it possible to stabilize only DC, the input voltage waveform has a similar shape to the voltage waveform.

In this embodiment, the on time is generated almost inversely proportional to the effective value of the input voltage, but the same effect can be obtained even if the on time is made almost inversely proportional to the average value.

FIG. 3 is a diagram for explaining another embodiment of the present invention, in which a bandpass filter 24 is inserted into the output voltage detection section of the circuit shown in FIG. 1, and the fundamental frequency component of the full-wave rectified voltage E is After removing the signal, it is input to the Il difference amplifier 11 in order to improve the response to load fluctuations and input fluctuations.

FIG. 4 is a diagram for explaining another embodiment of the present invention, in which a high-speed response converter circuit 2 is connected to the output section of the circuit shown in FIG.
5 are connected. In the embodiment shown in Fig. 1, the response is slow, and even in the embodiment shown in Fig. 3, there is voltage pulsation in the fundamental frequency component of the full-wave rectified voltage, which may cause a problem with the load, or if input/output insulation is required. 'ii! It performs stabilization control, insulates the main output, and supplies power with good zero voltage to the load. Since this converter circuit 11326 is well known, a description of its operation will be omitted.Although a forward converter is shown in this example, the same effect can be obtained with any circuit configuration such as a flyback converter. can get.

FIG. 5 is a diagram for explaining another embodiment of the present invention, in which a flyback type ■
It is used when it is necessary to insulate the output of one person.

In FIG. 5, an AC voltage is connected to the input voltage of a full-wave rectifier circuit 2 via a high-frequency filter l, and the full-wave rectifier circuit 2
A series circuit of the primary S line Nl of the transformer 26 and the switching element 4 is connected between the DC output voltages of the transformer 26 and the switching element 4. Then, a series circuit of a rectifying diode 7 and a smoothing capacitor 9 is connected to the secondary winding N2 of the transformer 260, and the smoothing capacitor 9
Output is taken from between the voltages. To stabilize the output voltage m11m, an on-time generating circuit I5 generates a time that is almost inversely proportional to the effective value of the input voltage, and a 1% difference amplifying circuit I6
, the output 14IEE is divided by a resistor 17.18,
The WA difference with the reference voltage E rpf is amplified by the error amplifier 11 and isolated by the photocoupler 27 , a time approximately proportional to the error voltage is generated by the off time generation circuit 11819 , and these times are sent to the drive circuit 20 . In this actual MN, which is performed by turning on and off the switching element 4, the operation is almost the same as that described in the embodiment of FIG. 1, and the same effects can be obtained.

In this embodiment, the on time is generated almost inversely proportional to the effective value of the input voltage, but the same effect can be obtained even if the on time is made almost inversely proportional to the average value.

FIG. 6 is a diagram for explaining another embodiment of the present invention, in which a bandpass filter 24 is inserted in the output voltage detection section of the circuit of FIG. is removed, and then input manually to the error amplifier 11 in order to improve 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 17 circuit 232 is provided at the output section of the circuit shown in FIG.
8 are connected. In the actual S example 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 total i11 rectified voltage, which causes problems with the U load, but it stabilizes quickly! 4 control, and is configured to supply power with a good voltage opening to the f1 load. Furthermore, this chi M
Since the 7P circuit 28 is well known, a description of its operation will be omitted.

〔Effect of the invention〕

As explained above, the present invention does not use a special circuit such as a current detection current transformer or VCA for current waveform control, and has a simple configuration that allows the input voltage waveform to be changed to the input voltage waveform. It can be made to have a similar shape, as if a resistor was connected to the input voltage, and the power factor of the input can be improved.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 are diagrams for explaining one embodiment of the present invention, and FIGS. 3 to 7 are diagrams for explaining one embodiment of the present invention, respectively. FIGS. 8 and 9 are diagrams for explaining conventional examples. l...High frequency filter 2...Full wave rectifier circuit 3.
... Chigofva circuit 4.5... Switching element 6... Chitark coil 7... Rectifier diode 8... Flywheel diode 9... Smoothing capacitor 10... fL current flow device 11.
-・Error amplifier 12...VCA! 3...Differential amplifier 14...-Pulse width control circuit 15...
・On time generation circuit 16・-・Ig4 difference amplifier circuit 19
... Off time generation circuit 22 ... Capacitor 24 ... Bandpass filter circuit 27 ... Photocoupler circuit 17, 18 ... Resistors 20, 21 ... Drive circuit 23 ... Resistor 25 ...High-speed response comparator 26...Transformer 28...High-speed response selector

Claims (5)

[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 ON time of the switching element is a predetermined time approximately inversely proportional to the effective value of the input voltage, and the OFF time is a predetermined time approximately proportional to the output voltage. (2) A full-wave rectifier circuit that full-wave rectifies the 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 ON time of the switching element is a predetermined time approximately inversely proportional to the average value of the input voltage, and the OFF time is a predetermined time approximately proportional to the output voltage. (3) 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 Control of a converter characterized in that the current is reset every time the switching element is switched, the on time of the switching element is set to a predetermined time approximately inversely proportional to the effective value of the input voltage, and the off time is set to a predetermined time approximately proportional to the output voltage. Method. (4) 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 Control of a converter characterized in that the current is reset every time the switching element is switched, the on time of the switching element is set to a predetermined time approximately inversely proportional to the average value of the input voltage, and the off time is set to a predetermined time approximately proportional to the output voltage. Method. (5) The converter control method according to claim 1, 2, 3 or 4, wherein the off-time of the switching element is made not to respond to the fundamental frequency of the full-wave rectified voltage.