JP3486603B2 - Power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device, and more particularly to a power supply device for converting an AC voltage into a DC voltage.

[0002]

2. Description of the Related Art A capacitor input type rectifier circuit is widely used as a power supply circuit for obtaining a DC voltage from an AC voltage of a commercial power supply or the like.

A typical circuit diagram of a capacitor input type rectifier circuit is described, for example, in FIG. 5 of JP-A-4-138506. As described in the publication, in the capacitor input type rectifier circuit, an input smoothing capacitor is inserted between both output terminals of the input rectifying diode, and the output voltage from the input rectifying diode is generated by the input smoothing capacitor. The pulsating flow is smoothed.

However, in the capacitor-input type rectifier circuit, the input current becomes a pulse current flowing for a very short time every half cycle of the input voltage, and contains many harmonic components. Therefore, the power factor is very low, voltage distortion occurs, reactive power increases, and the power supply equipment is adversely affected.

[0005]

In order to solve such a problem, a method of inserting a booster circuit between an input rectifying diode and an input smoothing capacitor has been proposed (see FIG. 8 of the same publication). . According to this method, the power factor can be brought close to 1, but there is a problem that the conversion efficiency is lowered due to the loss of the booster circuit.

On the other hand, a method has also been proposed in which an input smoothing capacitor is not provided in the subsequent stage of the input rectifying diode and the output rectifying diode is directly connected to the primary winding of the high frequency transformer via a switching transistor. (See FIG. 1 of the same publication). According to this method, the power factor can be improved by optimally controlling the conduction / non-conduction of the switching transistor, but the input current does not flow when the input voltage is low, so that the power factor is almost 1. You cannot do it. There is also a problem that the harmonic components contained in the input current cannot be effectively removed.

Therefore, an object of the present invention is to provide a power supply device which can improve the power factor and can effectively remove the harmonic components contained in the input current while suppressing the decrease in the conversion efficiency. That is.

[0008]

The object of the present invention is to:
An input rectifying means for rectifying an input voltage supplied from an AC power source, a transformer for receiving an output from the input rectifying means in a primary winding, and an output rectifying circuit for smoothing an output from a secondary winding of the transformer. A booster circuit for boosting the output voltage of the input rectifying means and supplying the booster voltage to the primary winding of the transformer; and a first control means for controlling the operation of the booster circuit, wherein the booster circuit comprises: An inductor and a first switch means connected in series, the input rectifying means,
At least a first input rectifier circuit and a second input rectifier circuit are included, the first control means is set to a first state periodically, and the output voltage of the first input rectifier circuit, A second input rectifier circuit is provided with a latch circuit that is brought into a second state based on the output voltage and the input current to determine conduction / non-conduction of the first switch means, and is supplied from the AC power supply. In response to the instantaneous value of the input voltage becoming equal to or lower than a predetermined voltage, the waveform of the input current supplied from the AC power supply and the waveform of the output voltage of the input rectifying means have similar shapes, By controlling conduction / non-conduction of the first switch means, the voltage of the primary winding of the transformer is configured to be boosted, and the first input rectifier circuit and the primary winding of the transformer are configured. Through the booster circuit Without being connected, the second input rectifier circuit and the primary winding of the transformer are configured to be connected via the booster circuit. .

According to the present invention, the voltage of the primary winding of the transformer is boosted in response to the instantaneous value of the input voltage becoming equal to or lower than the predetermined voltage, and the instantaneous value of the input voltage becomes equal to or higher than the predetermined voltage. In some cases, since such boosting is not performed, the input current supplied from the AC power supply flows into the primary winding of the transformer without passing through the boosting means when the instantaneous value of the input voltage is equal to or higher than a predetermined voltage. Therefore, it is possible to minimize the decrease in conversion efficiency due to the interposition of the booster.

In a preferred aspect of the present invention, the transformer has a winding ratio of the primary winding and the secondary winding of 1: n, and the predetermined voltage is output from the output rectifying circuit. Output voltage divided by n.

According to the preferred embodiment of the present invention, since the predetermined voltage is defined by the voltage obtained by dividing the output voltage output from the output rectifying circuit by n, the instantaneous value of the input voltage is reduced and In response to the fact that the current has stopped flowing in the next winding, the boosting means boosts the voltage. Therefore, even if the instantaneous value of the input voltage drops and the current does not flow in the primary winding of the transformer, the input current can always flow from the AC power supply, and as a result, the input current waveform is input. It is possible to match the voltage waveform. Thereby, the power factor can be improved.

[0012] In a further preferred aspect of the present invention, the boosting means boosts an output from the second input rectifying means for rectifying the input voltage and an output from the second input rectifying means for boosting the output of the transformer. A booster circuit for supplying the primary winding.

In a further preferred aspect of the present invention, there is further provided switch means for making the voltage waveform of the primary winding of the transformer a pulse waveform.

In a further preferred aspect of the present invention, a control signal having a sine wave waveform synchronized with the phase of the AC power supply is generated based on at least one of an output voltage and an output current output from the output rectifier circuit. The sine wave generating means, the current detecting means for detecting a current flowing through the primary winding of the transformer, the current waveform of the current detected by the current detecting means is generated by the sine wave generating means. It further comprises control means for controlling the switching of the switch means so as to match the waveform of the control signal.

According to a further preferred embodiment of the present invention, since the current waveform of the current flowing through the primary winding of the transformer is sinusoidal, the waveform of the input current can be matched with the waveform of the input voltage. . Thereby, the power factor can be improved. Further, since the current waveform of the current flowing through the primary winding of the transformer is determined based on at least one of the output voltage and the output current output from the output rectifier circuit, the output voltage output from the output rectifier circuit is kept constant. In either case, in order to keep the output current output from the output rectifier circuit constant, or to keep the output power output from the output rectifier circuit constant, the switching means of It becomes possible to perform switching.

[0016] In a further preferred aspect of the present invention, the sine wave waveform of the control signal generated by the sine wave generating means includes a harmonic component.

In a further preferred aspect of the present invention, the sine wave generating means is responsive to at least one of an output voltage, an output current and an output power output from the output rectifier circuit being larger than a desired value. Decreasing the amplitude of the control signal and increasing the amplitude of the control signal in response to being less than a desired value.

In a further preferred aspect of the present invention, the control means includes comparison means for comparing the current detected by the current detection means with the control signal supplied from the sine wave generation means. At least the switching of the switch means is controlled in response to the result of the comparison by the comparison means.

[0019] In a further preferred aspect of the present invention, the control means keeps at least one of the output voltage, the output current and the output power output from the output rectifier circuit substantially constant, and the AC power source. The waveform of the input current supplied by the device is a sine wave.

In a further preferred aspect of the present invention, the control means is in one state in response to the oscillator for generating an oscillation signal and the oscillation signal, and is in the other state in response to the result of the comparison by the comparison means. And a latch circuit which is in a state, and switching of the switch means is controlled based on the state of the latch circuit.

[0021]

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram showing a power supply device according to a preferred embodiment of the present invention.

As shown in FIG. 1, the power supply device according to the present embodiment has a first input rectifier circuit 10, a second input rectifier circuit 20, a booster circuit 30, and a switch circuit 40.
And an output rectifying circuit 50 and a control unit 60.

The first input rectifying circuit 10 is composed of four diodes 11-14.
The cathodes of 1 and 12 are commonly connected and connected to the signal line X1, and the anodes of the diodes 13 and 14 are commonly connected and connected to the signal line X2. Further, the anode of the diode 11 and the cathode of the diode 13 are commonly connected to the input terminal IN1 to which one end of the AC power source 1 is connected via the input filter 2, and the anode of the diode 12 and the cathode of the diode 14 are connected to the input filter. 2 is commonly connected to an input terminal IN2 to which the other end of the AC power supply 1 is connected. The AC power supply 1 connected between the input terminals IN1 and IN2 is a power supply that supplies an input voltage Vin and an input current Iin to the power supply device according to this embodiment, and is, for example, a commercial power supply. The first input rectifier circuit 10 having such a configuration receives the input voltage Vin supplied from the AC power supply 1 via the input filter 2 and full-wave rectifies it.

The second input rectifier circuit 20 is composed of two diodes 21 and 22, and the cathodes of the diodes 21 and 22 are commonly connected and connected to the signal line X3. The anode of the diode 21 is
It is connected to the input terminal IN2 via the input filter 2, and the anode of the diode 22 is connected to the input terminal IN1 via the input filter 2. The second input rectifier circuit 20 having such a configuration receives the input voltage Vin supplied from the AC power supply 1 via the input filter 2 and full-wave rectifies it.

The booster circuit 30 includes an inductor 31, a switch element 32 formed of a field effect transistor, a diode 33, a capacitor 34, and a current detecting element 35. The inductor 31 has one end connected to the signal line X3 and the other end connected to the anode of the diode 33. The cathode of the diode 33 is the signal line X.
Connected to 1. The switch element 32 has one end connected to the node between the inductor 31 and the anode of the diode 33, and the other end connected to the signal line X2. Further, the capacitor 34 is connected between the cathode of the diode 33 and the signal line X2. Since the capacitor 34 is used as a high frequency filter, its capacitance value may be small. Therefore, the capacitor 34 does not have a sufficient smoothing function in the frequency band of the commercial power source. Further, the current detection element 35 is the switching element 3 of the signal line X2.
It is connected between the other end of 2 and the common anode of the diodes 13 and 14 included in the first input rectifier circuit 10, and the current Ia flowing therethrough is detected. The booster circuit 30 having such a configuration receives the pulsating current supplied from the signal line X3, which is the output signal line of the second input rectifier circuit 20, and boosts the pulsating current to generate the first input rectifier circuit 10. The voltage of the signal line X1, which is the output signal line of the above, is increased.

The switch circuit 40 comprises a high frequency transformer 41.
And a switch element 44 composed of a field effect transistor
And a current detection element 45. The high frequency transformer 41 includes a primary winding 42 having a winding ratio of 1: n.
And the secondary winding 43, one end of the primary winding 42 is connected to the signal line X1, and the other end is connected to one end of the switch element 44. The other end of the switch element 44 is connected to the signal line X2. Further, the current detection element 45 is
Of the signal line X2, it is connected between the other end of the switch element 44 and the other end of the switch element 32, and a current I flowing therethrough.
c is detected. Switch circuit 4 having such a configuration
0 causes the power waveform appearing on the signal line X1 to be a pulse waveform by switching the switch element 44.

The output rectifying circuit 50 includes two diodes 5
1 and 52, inductor 53, capacitor 54,
The current detecting element 55 is included. In the diode 51, the anode is the secondary winding 4 of the high frequency transformer 41.
3 and the cathode is connected to one end of the inductor 53. The diode 52 has an anode connected to the other end of the secondary winding 43 of the high frequency transformer 41 and a cathode connected to one end of the inductor 53. One end of the capacitor 54 is connected to the other end of the inductor 53,
The other end is connected to the anode of the diode 52. Further, one end of the capacitor 54 is connected to the output terminal OUT1 to which one end of the load 3 is connected, and the other end of the capacitor 54 is connected to the output terminal OUT2 to which the other end of the load 3 is connected. Further, the current detection element 55 has an output terminal OUT.
2 and the other end of the capacitor 54, and detects the current Iout flowing there. The output rectifier circuit 50 having such a configuration smoothes the pulse waveform of the output from the switch circuit 40 and converts it into direct current.

The control unit 60 includes three control circuits 61 to 63.
And a pulse transformer 64 and a zero-cross detection circuit 65. The control circuit 61 has input terminals a and b.
And c and an output terminal d, the input terminal a is supplied with the voltage Va appearing on the signal line X3, and the input terminal b is supplied with information indicating the current Ia detected by the current detection element 35.
The voltage Vb appearing on the signal line X1 is supplied to the input terminal c. A control signal for controlling the switching of the switch element 32 is output from the output end d. Control circuit 62
Has input ends e, f and g and an output end h, the input end e is supplied with information indicating the current Iout detected by the current detection element 55, and the input end f is a voltage appearing on the output terminal OUT1. Vout is supplied, and the output signal output from the output terminal o of the zero-cross detection circuit 65 is supplied to the input terminal g. The control signal cntrl is output from the output terminal h.
Is output. The control circuit 63 includes input terminals i and j and an output terminal k, a control signal cntrl is supplied to the input terminal i, and information indicating the current Ic detected by the current detection element 45 is supplied to the input terminal j. It Further, a control signal for controlling switching of the switch element 44 is output from the output end k via the pulse transformer 64. The zero-cross detection circuit 65 includes input terminals 1 and m and an output terminal o, and the input terminal 1 is connected via an input filter 2 to an input terminal IN1 to which one end of an AC power supply 1 is connected. Similarly, the input end m is connected to the input terminal IN2 to which the other end of the AC power supply 1 is connected via the input filter 2. Further, the output terminal o outputs the zero-cross detection signal zero each time the input voltage Vin supplied from the AC power supply 1 connected between the input terminals IN1 and IN2 crosses the zero voltage, and as described above, the control circuit It is supplied to the input terminal g of 62. The control unit 60 having such a configuration controls the operation of the entire power supply device according to the present embodiment, and outputs the output voltage V
In addition to stabilizing out, the current waveform of the input current Iin is shaped into a sine wave to improve the power factor.

FIG. 2 is a block diagram showing the circuit configuration of the control circuit 61.

As shown in FIG. 2, the control circuit 61 includes
Multiplier 71, comparator 72, oscillator 73, R
The S latch circuit 74 is included.

The oscillator 73 has a predetermined frequency, for example, 10
This is a circuit that generates a triangular wave having a frequency of 0 kHz to 200 kHz, and the generated triangular wave is an RS latch circuit 7
4 set input terminals (S). Multiplier 71
Receives the voltage Va supplied from the input terminal a and the voltage Vb supplied from the input terminal c, performs necessary calculations on these, and supplies the result to the inverting input terminal (−) of the comparator 72. Information indicating the current Ia supplied from the input terminal b is input to the non-inverting input terminal (+) of the comparator 72. The comparator 72 compares the calculation result obtained by the multiplier 71 with the information indicating the current Ia, and calculates the current Ia.
The high level output is supplied to the reset input terminal (R) of the RS latch circuit 74 in response to the information indicating that exceeds the calculation result by the multiplier 71. RS latch circuit 74
Sets the level of the signal output from the output terminal (Q) to low level in response to the high level of the signal supplied to the reset input terminal (R), and supplies the signal to the set input terminal (S). The level of the signal output from the output terminal (Q) in response to the high level of the signal is set to the high level.

The control circuit 61 having such a configuration is
The voltage Vb appearing on the signal line X1 is output voltage Vout / n
(N: turn ratio of the primary winding 42 and the secondary winding 43 of the high frequency transformer 41) and more, and further, the voltage waveform of the voltage Va appearing on the signal line X3 and the current detected by the current detection element 35. So that the current waveform of Ia is similar,
Moreover, the conduction / non-conduction of the switch element 32 in the booster circuit 30 is controlled so that the voltage across the capacitor 34 is maintained substantially constant.

That is, the winding ratio of the primary winding 42 and the secondary winding 43 of the high frequency transformer 41 is 1: n, and the voltage Vs generated between the secondary winding 43 of the high frequency transformer 41 is 1
Although it is n times the voltage Vb generated between the secondary windings 42, if the voltage Vs generated between the secondary windings 43 is lower than the output voltage Vout supplied to the load 3, the secondary winding 43
No current flows from the load to the load 3. The fact that the current does not flow to the load 3 means that the input current Iin does not flow, so that the input current Iin does not flow when the voltage Vb is lower than the voltage Vout / n. If the period during which the input current Iin does not flow becomes long, the harmonic component of the input current will increase. Therefore, the control circuit 61 controls the voltage V appearing on the signal line X1 via the input terminal c.
b is monitored, and in a region where the voltage Vb cannot be maintained at the voltage Vout / n or more by the first input rectifier circuit 10, a pulsed control signal is supplied to the switch element 32 through the output terminal d to switch the switch element 32. Are switched, and the boosting circuit 30 starts boosting.

More specifically, the first input rectifying circuit 10
In the region where the voltage Vb cannot be maintained at the output voltage Vout / n or higher by the, the RS latch circuit 74 is set when the level of the triangular wave supplied from the oscillator 73 reaches a predetermined level, and sets its output to the high level. As a result, the switch element 32 becomes conductive. After that, the RS latch circuit 74 causes the calculation result by the multiplier 71 and the current Ia.
Is reset at a predetermined timing based on the information indicating
The output is set to low level. As a result, the switch element 32 is turned off. Here, the "predetermined timing" is an element that determines the duty of the output waveform from the output end d. In other words, the duty of the output waveform from the output terminal d is determined by the timing at which the output of the comparator 72 becomes high level after the switch element 32 becomes conductive. The duty is the waveform of the voltage Va supplied to the input end a and the current I supplied to the input end b as a result of switching by the switch element 32.
The waveform of a has a similar shape, and the capacitor 34
It is determined so that the voltage across V is maintained approximately constant.

On the other hand, in the region where the voltage Vb can be maintained at the output voltage Vout / n or higher by the first input rectifier circuit 10, the comparator 72 maintains its output at a high level, whereby the RS latch circuit 74 causes the oscillator. The reset state is maintained regardless of the input from 73 to the set input terminal (S). Therefore, the output from the output terminal d is maintained at a low level (duty = 0), and the switch element 32 becomes non-conductive. As a result, the boosting operation by the booster circuit 30 is stopped.

In this way, the control circuit 61 controls the switch element 32 so that the voltage Vb does not drop below the output voltage Vout / n, so that the input voltage Vin is equal to the output voltage Vout.
When it is out / n or more, the input current Iin directly flows into the switch circuit 40 via the first input rectifying circuit 10, and when the input voltage Vin is the output voltage Vout / n or less, the voltage Vb is The input current Iin cannot flow into the switch circuit 40 via the first input rectifier circuit 10 because the output voltage Vout / n or more is held, and the second input rectifier circuit 20 and the booster circuit 30 are not provided. Will flow into the switch circuit 40 via.

As the control circuit 61 having such a function, for example, a power control IC: U manufactured by UNITRODE
There is C3854B.

FIG. 3 is a block diagram showing the circuit configuration of the control circuit 62.

As shown in FIG. 3, the control circuit 62 includes
Multiplexer 81, A / D converter 82, interrupt controller 83, processor core 84, R
It is configured to include an OM 85, a timer 86, a RAM 87, and an I / O controller 88.

The multiplexer 81 receives the output current Iout supplied from the input terminal e and the output voltage Vout supplied from the input terminal f, and supplies one of them to the A / D converter 82. The A / D converter 82 converts the output current Iout or the output voltage Vout supplied via the multiplexer 81 into digital information. The interrupt controller 83 receives the zero-cross detection signal zero supplied from the input terminal g and issues an interrupt to the processor core 84 each time it is activated. The processor core 84 is a control unit that controls the overall operation of the control circuit 62. The ROM 85 is the processor core 84
Stores a program showing a processing procedure to be performed by the program and basic data obtained by dividing a waveform of a half cycle of a sine wave having an amplitude of 1 (half-sine waveform) into 128 in the time axis direction,
Of the basic data, the data stored at the head address is read by the processor core 84 in response to the interrupt signal issued by the interrupt controller 83. After the interrupt signal is issued from the interrupt controller 83, the timer 86 generates an interrupt signal in a cycle of 78 μsec (when the AC power supply 1 is a commercial power supply of 50 Hz), and the processor core 84 receiving this generates the interrupt signal.
Of the basic data stored in the ROM 85, the data stored at the next address is read. RAM87
Is a work area used for calculation by the processor core 84. The I / O controller 88 is a processor
This is an interface circuit for outputting the data obtained by the calculation by the core 84 from the output end h as the control signal cntrl.

The control circuit 62 having such a configuration is
In this embodiment, the output voltage Vout is monitored,
The control signal cntrl is controlled so that it has a constant voltage value.
To generate.

Specifically, first, the output voltage Vout converted into digital information by the A / D converter 82 via the multiplexer 81 is converted into predetermined parameters under the control of the processor core 84. on the other hand,
As described above, when the zero-cross detection signal zero supplied from the input terminal g is activated, the data stored at the head address of the basic data stored in the ROM 85 is read by the processor core 84. The processor core 84 compares the obtained parameter with a parameter indicating the reference value of the output voltage Vout. As a result of the comparison, if the obtained parameter is larger than the parameter indicating the reference value, it means that the output voltage Vout supplied between the output terminals OUT1 and OUT2 is larger than the reference value. Is decreased and the value is output from the output terminal h via the I / O controller 88. On the contrary, if the obtained parameter is smaller than the parameter indicating the reference value, it means that the output voltage Vout supplied between the output terminals OUT1 and OUT2 is smaller than the reference value. Increase the value shown and change this to I / O
Output from the output terminal h via the controller 88.

Next, 78 μsec after the interrupt signal is issued from the interrupt controller 83, the timer 86
An interrupt signal is generated by the processor core 84, and in response thereto, the processor core 84 reads out the data stored at the next address from the basic data stored in the ROM 85. The data read in this way is also reduced or increased based on the result of comparison of the above parameters by the processor core 84, and is output from the output end h.

Such processing is performed one after another each time an interrupt signal is generated by the timer 86. As a result, the control signal cntrl having a waveform corresponding to the output voltage Vout supplied between the output terminals OUT1 and OUT2 is output from the output terminal h, and this is the control circuit 63 as described above.
Is supplied to the input terminal i.

As the control circuit 62 having such a function, for example, a microcontroller manufactured by NEC: μP
There is D78324.

FIG. 4 is a block diagram showing the circuit configuration of the control circuit 63.

As shown in FIG. 4, the control circuit 63 has
Comparator 91, oscillator 92, RS latch circuit 9
3 is included.

The comparator 91 receives the control signal cntrl supplied from the input terminal i from the inverting input terminal (-) and the information indicating the current Ic supplied from the input terminal j from the non-inverting input terminal (+). Comparing these, the current Ic
The high level output is supplied to the reset input terminal (R) of the RS latch circuit 93 in response to the information indicating that the control signal cntrl has exceeded. The oscillator 92 is a circuit that generates a triangular wave having a predetermined frequency, for example, a frequency of 100 kHz to 200 kHz, and the generated triangular wave is R.
It is supplied to the set input terminal (S) of the S latch circuit 93. The RS latch circuit 93 sets the level of the signal output from the output terminal (Q) to low level in response to the high level of the signal supplied to the reset input terminal (R), and sets the set input terminal (S). The level of the signal output from the output terminal (Q) is set to the high level in response to the high level of the signal supplied to.

The control circuit 63 having such a configuration is
The pulse current Ic detected by the current detection element 45 is monitored, and the switching element is provided via the pulse transformer 64 so that the current waveform of the pulse current Ic matches the waveform of the control signal cntrl supplied from the control circuit 62. Control 44. Specifically, the drive signal of the switch element 44 output from the output end k becomes high level in response to the triangular wave supplied from the oscillator 92 becoming high level and the RS latch circuit 93 being set, and thereafter,
It becomes low level in response to the information indicating the current Ic becoming larger than the control signal cntrl. This allows
The waveform of the current Ic is a waveform whose peak is limited by the control signal cntrl.

As the control circuit 63 having such a function, for example, a power control IC: U manufactured by UNITRODE
There is C3825.

Next, the operation of the power supply device according to the preferred embodiment of the present invention will be described.

FIG. 5 is a voltage waveform and a current waveform showing the operation of the power supply device according to the preferred embodiment of the present invention.

As shown in FIG. 5, the waveform of the input voltage Vin of the AC power supply 1 is sinusoidal, and the voltage Va after full-wave rectifying the input voltage Vin by the second input rectifying circuit 20 becomes a pulsating flow. The voltage Vb after full-wave rectification of the input voltage Vin of the AC power supply 1 by the first input rectifier circuit 10 also tries to become a pulsating current. However, as described above, the voltage boosted by the booster circuit 30 results in the voltage Vout / n (n: high frequency transformer 4
The winding number ratio of the primary winding 42 and the secondary winding 43 of 1) or less does not decrease, and as a result, the waveform becomes as shown in FIG.

More specifically, at time t0 when the input voltage Vin crosses the zero voltage, the signal line X1 is boosted by the booster circuit 30, and the voltage Vb on the signal line X1 is V.
Since it is maintained at out / n or more, the input current Iin
Cannot flow directly into the capacitor 34, but flows into the capacitor 34 via the booster circuit 30. At this time, as described above, the control circuit 61 keeps the voltage across the capacitor 34 substantially constant, and the input voltage V
The switching of the switch element 32 is controlled so that the waveform of in and the waveform of the input current Iin are substantially similar to each other.

This operation is performed until time t1 when the instantaneous value of the input voltage Vin becomes higher than the output voltage of the booster circuit 30. When the instantaneous value of the input voltage Vin becomes higher than the output voltage of the booster circuit 30, the control circuit 61 stops switching of the switch element 32 as described above, so that boosting by the booster circuit 30 is stopped. As a result, the input current Iin directly flows into the capacitor 34 without passing through the booster circuit 30. As mentioned above, capacitor 3
Since the capacity of 4 is small and has substantially no smoothing effect,
The voltage Vb, which is the voltage across the capacitor 34, becomes substantially equal to the input voltage Vin, and the voltage Vb is the input voltage Vi.
It changes following the change of n.

After that, when the instantaneous value of the input voltage Vin becomes lower than the output voltage of the booster circuit 30 again at the time t2, the control circuit 61 restarts the switching by the switch element 32 again and performs the boosting operation by the booster circuit 30. Voltage Vb is maintained at Vout / n or higher. This operation is performed until time t3 when the instantaneous value of the input voltage Vin becomes higher than the output voltage of the booster circuit 30.

As described above, in the power supply device according to the preferred embodiment of the present invention, the instantaneous value of the input voltage Vin is Vou.
When it is higher than t / n, the booster circuit 30 does not boost the voltage, and the input current Iin flows into the switch circuit 40 without passing through the booster circuit 30.
The reduction in conversion efficiency due to the interposition of is minimized. In addition, the instantaneous value of the input voltage Vin is Vout / n
When it is lower than the above, the voltage is boosted by the voltage boosting circuit 30 and the voltage Vb is maintained at Vout / n or more, so that the input current Iin can be constantly supplied, and as a result, the input current Iin
It is possible to match the waveform of in with the waveform of the input voltage Vin. Thereby, the power factor can be improved.

Since the capacitance of the capacitor 34 is small, the input current Iin follows changes in the current Ic flowing through the primary winding 42 of the high frequency transformer 41 of the switch circuit 40. Therefore, the waveform of the input current Iin is converted to the input voltage Vi.
The current Ic flowing through the primary winding 42 of the high-frequency transformer 41 needs to be sinusoidal in order to have the same sinusoidal waveform as the waveform of n and bring the power factor close to 1.

FIG. 6 is a waveform diagram showing the operation of the control circuit 63.

As shown in FIG. 6, when the drive signal of the switch element 44 output from the output terminal k becomes high level, the switch element 44 becomes conductive and the current Ic increases, but the amount of the current Ic is reduced. When the value indicated by the control signal cntrl is reached, the output of the comparator 91 becomes high level, the RS latch circuit 93 is reset, and the switch element 44 becomes non-conductive. Then oscillator 9
The level of the triangular wave supplied from 2 becomes high level,
When the RS latch circuit 93 is set again, the switch element 44 becomes conductive, and the current Ic again starts to increase. As described above, since the frequency of the triangular wave supplied from the RS latch circuit 93 is, for example, 100 kHz to 200 kHz, the above operation is repeated at that frequency.

The peak of the current Ic is the control signal cn.
Since it is limited by trl, when the control signal cntrl changes, the peak of the current Ic also changes accordingly. For example, as shown in FIG. 6, the control signal cntr
If the level of l becomes low (control signal cntrl '), the peak of the current Ic can be suppressed low accordingly. As described above, the control signal cnt generated by the control circuit 62.
The level of rl decreases when the output voltage Vout supplied between the output terminals OUT1 and OUT2 is excessive,
If the output voltage Vout supplied between the output terminals OUT1 and OUT2 is too small, it rises. Therefore, the peak of the current Ic also decreases if the output voltage Vout supplied between the output terminals OUT1 and OUT2 is too large. , The output voltage V supplied between the output terminals OUT1 and OUT2
If out is too small, it rises. Accordingly, in the power supply device according to the preferred embodiment of the present invention, the output terminal OU
Output voltage Vout supplied between T1 and OUT2
Is stabilized and the current Ic flowing through the primary winding 42 of the high frequency transformer 41 becomes sinusoidal.

In order to bring the waveform of the input current Iin closer to a sine wave, the amount of the current Ic is changed to the capacitor 34 during the period in which the voltage is boosted by the booster circuit 30 (for example, time t2 to time t3). Of the input current I during the period (for example, time t1 to time t2) where the booster circuit 30 does not boost the current.
It is desirable to control the switching of the switch element 44 so that the waveform of in becomes similar to the waveform of the input voltage Vin. The reason will be described below.

FIG. 7 is a circuit diagram showing a state in which the AC power supply 1 is connected to the input side of the booster circuit 30 and the load 3 is connected to the output side. FIG. 8 is a diagram showing current waveforms of the input current Iin ₃₀ and the current Icin.

As shown in FIG. 7, when the AC power supply 1 is connected to the input side of the booster circuit 30, the input voltage Vin ₃₀
And the waveform of the input current Iin ₃₀ are both sine waves, the envelope of the current Icin flowing into the capacitor 34 when the switch element 32 is in the non-conducting state is as shown in FIG. _The current waveform has twice the frequency component of ₃₀ .

Because the current Icin flowing into the capacitor 34 is

[0067]

[Equation 1] Therefore, since the waveforms of the input voltage Vin ₃₀ and the input current Iin ₃₀ are both sine waves,

[0068]

[Equation 2] Therefore, the current Icin flowing into the capacitor 34 has a current waveform having a frequency component twice that of the input current Iin ₃₀ .

On the other hand, in order for the voltage Vb to become constant, the current Icin flowing into the capacitor 34 and the capacitor 34
The current Icout flowing out from must be equal.

Therefore, in order to bring the waveform of the input current Iin closer to a sine wave, the amount of the current Ic is changed to the capacitor during the period (eg, time t2 to time t3) in which the booster circuit 30 is boosting. In order to make the waveform of the input current Iin similar to the waveform of the input voltage Vin during the period in which the booster circuit 30 does not perform boosting (for example, time t1 to time t2), the amount of current that flows into the voltage source 34 is made similar. It is desirable to control the switching of the switch element 44.

That is, the control signal cntrl generated by the control circuit 62 has a current waveform having a frequency component that is twice the input current Iin during the period in which the booster circuit 30 operates, and the booster circuit 30 operates. If the waveform of the input voltage Vin is similar during the non-use period, the input current Ii
The waveform of n will be closer to a sine wave.

As described above, according to the power supply device of this embodiment, the power factor is improved and the harmonic components contained in the input current are effectively removed while suppressing the decrease in conversion efficiency. It is possible to provide a power supply device that can do this.

According to the power supply device of this embodiment, a power factor of 0.99 and a harmonic current distortion rate (THD) of the input current Iin (THD) = 5.85% can be obtained.
The standard value of 61000-3-2 class A could be satisfied.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

For example, in the above embodiment, the control unit 60 is composed of three control circuits consisting of the control circuits 61 to 63. However, the control unit 60 is composed of only one control circuit having all the functions of these three control circuits. May be configured.

Further, in the above embodiment, the control circuit 62 compares the parameter generated based on the output voltage Vout with the parameter indicating the reference value of the output voltage Vout, and based on this, stored in the ROM 85. The control signal cntrl is generated by decreasing or increasing the value of the basic data stored therein, and thereby the output voltage Vout is stabilized. However, the present invention is not limited to this, and the output current Iout is stabilized, Output power (Vout x Io
ut) may be stabilized. In order to stabilize the output current Iout, the parameter generated based on the output current Iout is compared with the parameter indicating the reference value of the output current Iout, and based on this, the ROM
The control signal cntrl may be generated by decreasing or increasing the value of the basic data stored in 85. In order to stabilize the output power (Vout × Iout), both the output current Iout and the output voltage Vout are set. The parameter generated based on this is compared with the parameter indicating the reference value of the output power Vout × Iout, and based on this, the ROM 8
The control signal cntrl may be generated by decreasing or increasing the value of the basic data stored in 5.

Further, in the above-described embodiment, the control circuit 62 compares the parameter generated based on the output voltage Vout with the parameter indicating the reference value of the output voltage Vout, and based on this, stored in the ROM 85. The control signal cntrl is generated by decreasing or increasing the value of the basic data present, thereby matching the waveform of the input current Iin with the waveform of the input voltage Vin, and removing the harmonic component contained in the input current. However, during the period t2 to t3 when the boosting circuit 30 boosts the basic data stored in the ROM 85, the current amount of the current Ic and the current amount flowing into the capacitor 34 match, and the boosting circuit 3
In a period t1 to t2 in which the boosting by 0 is not performed, a harmonic component such that the waveform of the input current Iin and the waveform of the input voltage Vin match is included, whereby the harmonic component included in the input current is more effective. It may be configured to be removed selectively.

Further, in the present invention, the means does not necessarily mean a physical means but also includes a case where the function of each means is realized by software. Further, the function of one means may be realized by two or more physical means, or the functions of two or more means may be realized by one physical means.

[0079]

As described above, according to the present invention,
The power factor is improved while minimizing the decrease in conversion efficiency.
It is possible to provide a power supply device in which harmonic components included in the input current are effectively removed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a power supply device according to a preferred embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of a control circuit 61.

FIG. 3 is a block diagram showing a circuit configuration of a control circuit 62.

FIG. 4 is a block diagram showing a circuit configuration of a control circuit 63.

FIG. 5 is a voltage waveform and a current waveform showing the operation of the power supply device according to the preferred embodiment of the present invention.

FIG. 6 is a waveform diagram showing an operation of a control circuit 63.

FIG. 7 is a circuit diagram showing a state in which the AC power supply 1 is connected to the input side of the booster circuit 30 and the load 3 is connected to the output side.

FIG. 8 shows an input current Iin ₃₀ and a current Icin.
It is a figure which shows the current waveform of.

[Explanation of symbols]

1 AC power supply 2-input filter 3 load 10 First input rectifier circuit 11-14 Diode 20 Second input rectifier circuit 21, 22 Diode 30 booster circuit 31 Inductor 32 switch element 33 diode 34 capacitor 35 Current detection element 40 switch circuit 41 high frequency transformer 42 Primary winding 43 Secondary winding 44 switch element 45 Current detection element 50 output rectifier circuit 51,52 Diode 53 inductor 54 capacitor 55 Current detection element 60 control 61-63 control circuit 64 pulse transformer 65 Zero cross detection circuit 71 multiplier 72 Comparator 73 oscillator 74 RS latch circuit 81 Multiplexer 82 A / D converter 83 Interrupt controller 84 processor cores 85 ROM 86 timer 87 RAM 88 I / O controller 91 Comparator 92 oscillator 93 RS latch circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-177745 (JP, A) JP-A-11-89221 (JP, A) JP-A-10-14231 (JP, A) JP-A-4- 138506 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02M 7/12 H02M 3/155 H02M 3/28

Claims (7)

(57) [Claims] 1. An input rectifying means for rectifying an input voltage supplied from an AC power source, and an output from the input rectifying means
A transformer that receives a secondary winding, an output rectifier circuit that smoothes the output from the secondary winding of the transformer, and a booster that boosts the output voltage of the input rectifying means and supplies the voltage to the primary winding of the transformer. Circuit and first control means for controlling the operation of the booster circuit, wherein the booster circuit has an inductor and a first switch means connected in series, and the input rectifying means has at least a first An input rectifier circuit and a second input rectifier circuit, wherein the first control means is periodically set to the first state, the output voltage of the first input rectifier circuit, and the second input rectifier circuit. A latch circuit that is placed in a second state on the basis of the output voltage of the circuit and the input current to determine conduction / non-conduction of the first switch means, and the input voltage supplied from the AC power supply The instantaneous value is the specified In response to the following, the conduction / non-conduction of the first switch means is set so that the waveform of the input current supplied from the AC power supply and the waveform of the output voltage of the input rectification means have a similar shape. By controlling conduction, the voltage of the primary winding of the transformer is configured to be boosted, and the first input rectifier circuit and the primary winding of the transformer do not go through the booster circuit, A power supply device connected to the second input rectifying circuit and the primary winding of the transformer via the booster circuit. 2. The power supply device according to claim 1, further comprising second switch means for making a voltage waveform of the primary winding of the transformer into a pulse waveform. 3. A sine wave generating means for generating a control signal having a sine wave waveform synchronized with the phase of the AC power source, based on at least one of an output voltage and an output current output from the output rectifier circuit. Current detecting means for detecting a current flowing through the primary winding of the transformer,
Second control means for controlling switching of the second switch means such that the current waveform of the current detected by the current detection means matches the waveform of the control signal generated by the sine wave generation means. The power supply device according to claim 2, further comprising: 4. The power supply device according to claim 3, wherein the sine wave waveform of the control signal generated by the sine wave generating means includes a harmonic component. 5. The sine wave generating means is responsive to at least one of an output voltage, an output current and an output power output from the output rectifier circuit being larger than a desired value,
The power supply device according to claim 3 or 4, wherein the power supply device is configured to decrease the amplitude of the control signal and increase the amplitude of the control signal in response to being smaller than a desired value. 6. The second control means includes a comparison means for comparing the current detected by the current detection means with the control signal supplied from the sine wave generation means, and at least the comparison means. 6. The power supply device according to claim 3, wherein the power supply device is configured to control the switching of the second switch means in response to the result of the comparison according to. 7. The second control means keeps at least one of an output voltage, an output current, and an output power output from the output rectifier circuit substantially constant, and an input supplied from the AC power supply. 7. The power supply device according to claim 3, wherein the power supply device is configured to have a sinusoidal current waveform.