JP2550325B2 - Power supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power supply device that uses a discharge lamp lighting device, an inverter type motor drive device or the like as a load, and includes a power conversion means such as a chopper circuit or an inverter circuit. is there.

BACKGROUND ART In recent years, switching power supply devices have become widespread, but in general, this switching power supply device inputs a DC (smoothed) voltage and outputs an arbitrary voltage. Therefore, when inputting an AC power supply voltage, it is necessary to rectify it into a pulsating voltage with a rectifying element, smooth this pulsating voltage with a large-capacity capacitor, and supply it to the switching part. Is remarkably distorted, the peak value is remarkably high, and the input power factor is low.

This is because a large-capacity capacitor was connected after the rectifying element.

Therefore, various means for solving the problems have been conventionally proposed, and will be described below. First, an outline will be described and then individual contents will be described.

First shows in FIG. 7 to 9 figures, the drive power supply V _D to a DC power supply is controlled so that the voltage and similar of the AC power source Vs to the input current Is by the PWM control. Therefore, the distortion of the input current Is is improved and the input power factor is also improved.

However, because the driving power supply V _D is a DC voltage and has a constant value,
When the rectified output voltage Vi is low, the transistor Q ₁
Has the drawback of being overdriven.

In FIGS. 10 and 11, the drive power source V _D is an AC power source.
Since the full-wave rectified voltage of Vs is used, overdrive of the transistor Q ₁ does not occur. On the other hand, there is a drawback that the input current waveform is distorted due to the shortage of the driving voltage, and the input current waveform is distorted.

Next, the operation of the above-described conventional power supply device will be described.

The power supply device shown in FIG. 7 uses a so-called step-up / down chopper circuit. The AC power supply Vs shown in FIG. 8 (a) is full-wave rectified by a full-wave rectifier DB forming a rectifier circuit, and the power supply device shown in FIG. The full-wave rectified voltage Vi shown in FIG. 4) is inserted between the load R and the full-wave rectifier DB to switch the transistor Q ₁ which is a switching element at high speed. A current I _Q flows through the transistor Q ₁ when the transistor Q ₁ is turned on, and a high frequency current I _L shown in FIG. 8 (c) is caused to flow through the inductance element L to accumulate ergi. When the transistor Q ₁ is turned off, the inductance element L
To release energy stored in the diode D ₁ the current I _D
The capacitor C _{2 is used} for rectifying and smoothing, and the power source V ₀ is supplied to the load R. In this conventional example, since a large-capacity capacitor is not connected to the output terminal of the full-wave rectifier DB, the waveform of the input current Is is changed to the AC power supply Vs waveform depending on the control circuit CTRL that controls the switching of the transistor Q _1. It is possible to make them substantially coincident with each other as shown in FIG. Here, the control circuit CTRL detects the voltage V ₀ across the load R and detects the voltage.
The transistor drive pulse of the transistor Q ₁ is pulse-width modulated according to the above-mentioned voltage V ₀ so that V ₀ becomes constant.
It is PWM controlled and has an operating power supply.

By the way, the current flowing through the transistor Q ₁ which is a switching element becomes a high frequency triangular current whose envelope coincides with the input current as shown in FIG. 9 (d). Thus the peak of the current I _Q is in the vicinity of the peak of the input voltage is high, also low peak current I _Q in the vicinity zero crossing of the input voltage.

9 (a) to 9 (f) show the outputs of the control circuit CTRL and the respective parts of the drive circuit DR of the transistor Q _1. The control signal Va from the control circuit CTRL shown in FIG. When applied to the _second base, the control signal Va transistor Q ₂ is turned on, the current flows from the driving power source V _D to the primary winding n ₁ of the pulse transformer PT when the on the transistor Q _2. When this current flows, a voltage is generated in the secondary winding n ₂ of the pulse transformer PT, this voltage is limited by the base resistor R _B , and the base current I _B shown in FIG. 9 (c) is applied to the base of the transistor Q ₁ . Shed. At this time, the base voltage V _B applied to the base of the transistor Q ₁ is as shown in FIG. 9 (b). Now, when the transistor Q ₁ turns on, the transistor Q ₁
The current I _Q shown in FIG. The current I _Q is a triangular wave, as described above. When the transistor Q ₂ is turned off, the energy stored in the pulse transformer PT is generated in the opposite polarity, so that the transistor Q ₂ is reverse biased and turned off. Note that FIG. 9 (e) shows the current I _D due to energy release from the inductance element L, and FIG. 9 (f) shows the current I _L flowing through the inductance element L.

Using such a drive circuit DR makes it easy to use transistors
Q ₁ can be controlled by a transistor
The base current I _B to turn on the Q ₁ is where current I _Q is the maximum, or current I _Q at the peak of the input AC power source Vs voltage
Need to be designed. If the maximum value of the current I _Q and I _QP, than the current amplification factor hfe of the transistor Q _1, the I _B ≧ I _QP / hfe. Current I _Q in a low region of the input AC power source Vs voltage when thus does not become so large,
However, since the base current I _B is constant, there is a serious overdrive, which delays the switching of the transistor Q _{1 when it} is off, resulting in a large loss.

The circuit shown in FIG. 10 uses a pulsating current as shown in FIG. 11 (a) synchronized with the AC power supply Vs as the driving power supply V _D. According to this circuit, the circuit shown in FIG. 11 (c) is used. increases or decreases the current I _Q is proportional to the envelope of the voltage waveform of the AC power source Vs, 11
Since the base current I _B shown in FIG. 7B also increases / decreases according to the driving power supply V _D , that is, the AC power supply Vs voltage, the overdrive is almost constant over the entire area, and the switching loss due to this is small and good driving is achieved. You can However, near the zero cross of the AC power supply Vs, sufficient energy cannot be transmitted to the secondary winding n ₂ of the pulse transformer PT due to the voltage drop between the collector and emitter of the transistor Q ₂ and the transmission capability of the pulse transformer PT. Further, there is a voltage drop (about several hundred mV) between the base and emitter of the transistor Q ₁ , and if the voltage generated in the secondary winding n ₂ is low, the transistor Q ₁ cannot be turned on and the 11th
There is a problem that a current blocking section is generated like the currents I _B and I _Q shown in FIGS. 7B and 7C, and the waveform of the input current Is is distorted so that the original purpose cannot be achieved.

[Object of the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply device that converts power by a power conversion unit including a chopper circuit or an inverter circuit having a switching element. The present invention provides a power supply device capable of optimally driving a switching element in the entire region when the input voltage has a pulsating waveform.

DISCLOSURE OF THE INVENTION The present invention relates to an AC power supply, a rectifier circuit that full-wave rectifies the AC voltage of the AC power supply, and outputs a full-wave rectified voltage. A power conversion means composed of a chopper circuit for intermittently boosting or lowering the voltage by means of, a driving power supply for applying a voltage of a similar voltage waveform synchronized with the full-wave rectified voltage waveform to the switching element as a driving voltage, and the driving power source. In a power supply device including a control circuit that controls on / off of a driving voltage of a power source and applies an on / off signal to the switching element, a trough portion between a peak portion and a peak portion of the driving voltage of the driving power source. In the section including the zero voltage, the auxiliary voltage means for superimposing a direct current voltage on the current flowing through the switching element to such an extent that a rest section cannot be provided. Is what you do.

 The present invention will be described below with reference to examples.

Embodiment 1 FIG. 1 shows a circuit of Embodiment 1 of the present invention, in which a step-up / step-down chopper circuit similar to the step-up / step-down chopper circuit of FIG. 7 is used as a power conversion means, a full-wave rectifier DB, a transistor Q. The operation of the step-up / down chopper circuit composed of ₁ , the inductance element L, the diode D ₁ and the capacitor C ₂ is basically the same as that of the circuit of FIG.

Here the driving circuit DR is a driving means of the transistor Q ₁ which is the main structure of the present invention, an AC power source Vs shown in FIG. 2 (a) as a driving power source V _D is stepped down by the step-down transformer T, the step-down output Is full-wave rectified by the full-wave rectifier DB ₂ and the capacitors C ₄ and C ₅ are serially charged via the diode D ₃ so that the voltage of each capacitor C ₄ and C ₅ is output from the full-wave rectifier DB _2. It is set to 1/2 of the peak voltage value and capacitor C
Charge each of ₄ and C ₅ through the diodes D ₄ and D ₅ ,
A power supply circuit having an auxiliary power supply means for outputting a voltage waveform in which the valleys of the pulsating flow waveform shown in FIG.

Therefore, the same RW as the control circuit CTRL explained in the conventional example of FIG.
When the transistor Q ₂ is turned on by the control signal Va of the M type control circuit CTRL and current flows from the driving power supply V _D to the primary winding n ₁ of the pulse transformer PT, a voltage is applied to the secondary winding n _2. Occurs,
Base resistance R Figure 2 through _B (c) the base current is indicated I _B
Flows to the base of transistor Q ₁ . In this case, since there is no zero cross in the waveform of the drive power supply V _D , the AC power supply Vs
Sufficient base current I _B is obtained in the entire region of, and current I _B, I
_As shown in FIGS. 2 (c) and 2 (d), there is no quiescent period in _Q , so the input current Is is not distorted. In addition, the base current I _B can be optimally designed as I _B = I _Q / hfe except for the valley portion of the drive power source V _D voltage waveform (discharging section of capacitors C ₄ and C ₅ ), and loss in this portion is small. It will be.

Second Embodiment FIG. 3 shows a drive circuit DR of the present embodiment, in which the control circuit CTRL and the main circuit of the step-up / down chopper circuit are omitted.

In this drive circuit DR, the full-wave rectifier DB is used as the drive power supply V _D.
Charge the capacitor C ₆ from the ₂ output through the resistor R ₁ to the voltage Vc value determined by the Zener voltage of the Zener diode Z,
When the output of the full-wave rectifier DB ₂ falls below the voltage Vc value, a power supply circuit that discharges the charge stored in the capacitor C ₆ through the diode D ₆ is used as auxiliary power supply means, and the voltage waveform shown in FIG. 4 (b) is used. Is getting This voltage waveform is also a so-called valley filling waveform and has the same effect as that of the first embodiment. Here, the voltage Vc at the valley portion can be set lower by the Zener voltage than in the case of the first embodiment, and the design region where the base current I _B = I _Q / hfe can be made wider. The voltage Vc value can be arbitrarily set to the extent that the current I _B and I _Q do not have a pause period, and the switching loss can be reduced as compared with the first embodiment. Note the FIG. 4 (a) shows the voltage waveform of the AC power source Vs, the FIG (c) is the base current I _B of the waveform of the transistor Q _1, FIG. (D) shows each current I _Q flowing through the transistor Q ₁ s Show.

Embodiment 3 FIG. 5 shows the entire circuit of this embodiment. In this circuit, the transistor Q ₂ controlled by the primary winding n ₁ of the pulse transformer PT of the drive circuit DR and the control signal Va of the control circuit CTRL.
The voltage generated at both ends of the secondary winding N ₂ wound around the inductance element L of the chopper circuit is applied to the capacitor C ₇ connected in parallel to the series circuit with the diode C through the diode D ₇ , and is also used for the control circuit CTRL. This power supply Vcc voltage is supplied to the transistor Q ₃ , Zener diode Z ₁ , bias resistor
An arbitrary DC voltage Vc is obtained by a DC constant voltage circuit as an auxiliary power supply means composed of R ₂ and a smoothing capacitor C _8, and this DC voltage Vc is applied to both ends of the capacitor C ₇ via a diode D _8. There is.

Therefore, the transistor is controlled by the control signal Va of the control circuit CTRL.
Q ₂ is turned on, a DC voltage of DC constant voltage circuit by the on
Vc is the primary winding of the pulse transformer PT via the diode D _8.
When the transistor Q ₁ is turned on by the output voltage of the secondary winding n ₂ of the pulse transformer PT which is applied to n ₁ ,
Since the output voltage Vi of the full-wave rectifier DB shown in FIG. 6 (a) is applied to the primary winding N ₁ of the inductance element L, the envelope of the applied voltage substantially matches the waveform of the AC power supply Vs. . When the transistor Q ₁ turns off, the inductance element L
Since a constant direct-current voltage V ₀ is applied to, the envelope has a constant value. Therefore, the voltage V _L across the primary winding N ₁ of the inductance element L has a waveform as shown in FIG. 6 (c). The extraction and transformation to an arbitrary voltage value from the secondary winding N ₂ of the inductance element L, and the voltage V _L2 diode D
₇ a high-frequency component is removed by the capacitor C ₇ rectifies only the polarity at the time of the on transistor Q ₁ by, applying to the capacitor C ₃ to the DC voltage Vc of the DC constant voltage circuit to the voltage via a diode D ₈ As a result, the drive power source V _D voltage shown in FIG. 6 (d) is obtained.

This driving power supply V _D voltage has a voltage waveform in which the pulsating current waveform is filled in the valleys, and the voltage Vc can be set arbitrarily, so that the same effect as that of the second embodiment can be obtained. Moreover, since the pulsating current waveform portion is taken out from the inductance element L, the step-down transformer T or the like used in the above embodiment is unnecessary,
It is advantageous for downsizing.

EFFECTS OF THE INVENTION The present invention relates to an AC power supply, a rectifier circuit that full-wave rectifies the AC voltage of the AC power supply, and outputs a full-wave rectified voltage. A power conversion means composed of a chopper circuit for intermittently boosting or lowering the voltage by means of, a driving power supply for applying a voltage of a similar voltage waveform synchronized with the full-wave rectified voltage waveform to the switching element as a driving voltage, and the driving power source. In a power supply device including a control circuit that controls on / off of a driving voltage of a power source and applies an on / off signal to the switching element, a trough portion between a peak portion and a peak portion of the driving voltage of the driving power source. Since the auxiliary voltage means for superimposing a DC voltage to the extent that a rest period is not possible on the current flowing through the switching element is provided in the section including the zero voltage of The drive of the switching element can be optimized according to the change of the pressure to suppress the switching loss, and the switching operation of the switching element is possible even at the zero crossing part of the pulsating waveform, so the input current does not stop. Instead, the switching element can be optimally switched over the entire region.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the drive circuit of the same, and FIG. 3 is a second embodiment of the present invention.
4 is a circuit diagram of the driving circuit of FIG. 4, FIG. 4 is a waveform diagram for explaining the operation of the above driving circuit, and FIG. 5 is a circuit diagram of a third embodiment of the present invention.
FIG. 7 is a waveform diagram for explaining the operation of the above-mentioned drive circuit, FIG. 7 is a circuit diagram of the conventional example, FIGS. 8 and 9 are waveform diagrams for explaining the operation of the same, and FIG. FIG. 11 is a circuit diagram of the circuit, and FIG. 11 is a waveform diagram for explaining the operation of the above driving circuit. Q ₁ is a transistor, L is an inductance element, and V _D is a driving power supply.

Claims (1)

(57) [Claims] 1. An AC power supply, a rectifier circuit for full-wave rectifying an AC voltage of the AC power supply to output a full-wave rectified voltage, and a full-wave rectified voltage output from the rectifier circuit is intermittently turned on and off by a switching element. And a step-up or step-down chopper circuit for converting power, a drive power supply for applying a voltage of a similar voltage waveform synchronized with the full-wave rectified voltage waveform to the switching element as a drive voltage, and a drive for the drive power supply. In a power supply device comprising a control circuit that controls on / off of a driving voltage to apply an on / off signal to the switching element, a zero voltage in a valley portion between the peak portion and the peak portion of the driving voltage of the driving power source. The auxiliary voltage means for superimposing a direct current voltage on the current flowing through the switching element in such a range that does not allow a pause interval. Apparatus.