JPH0347066B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a base current supply method in a ringing current converter, in particular a method in which DC voltage is intermittently applied to the primary winding of the transformer and transformed to the secondary winding. A ringing current transformer is connected to the circuit that intermittently applies DC voltage to the primary winding to improve efficiency and prevent abnormal oscillations.
This relates to a base current supply method in a converter.

[Problems to be solved by conventional technology and invention]

Conventionally, a ringing current converter (hereinafter referred to as RCC ₎ as shown in _{FIG .} Since the flowing collector current I _c has a large peak current value, it is necessary to supply a base current commensurate with this peak current value. Therefore, when the capacitance is increased, the voltage generated in the _N2 winding for positive feedback in Figure 5 is transferred to the base current _IB of the transistor _Tr3 via the resistor _R1 , diode D and capacitor _C1 . When supplying the voltage, the Ohmitsu cross (heat loss) caused by the resistor R ₁ becomes large, and the base current is so-called short-circuited to control the voltage generated in the secondary winding N ₃ to a predetermined voltage. The capacitance of the circuit 21 also inevitably increases, resulting in a problem of deterioration of power conversion efficiency and an increase in the size of the circuit. In order to solve this problem, it is considered to use a transformer to supply the base current of the transistor _Tr3 . However, in this case, a current transformer circuit, which is a positive feedback circuit, is further inserted into the RCC circuit that continues oscillation by a positive feedback circuit, and the self-resonant frequency of the secondary winding of the current transformer causes the self-resonance. Excited oscillation may occur.

[Means for solving problems]

In order to solve the above problems, the present invention provides a circuit in which a DC voltage is intermittently applied to the primary winding of a transformer to obtain a transformed voltage to the secondary winding. By connecting a current transformer to a circuit that intermittently applies power and employing a circuit that prevents abnormal oscillations, we aim to improve power conversion efficiency and stabilize operation. Therefore, the base current supply method in the ringing current converter of the present invention is as follows:
A transistor is connected to the primary winding of the transformer, the voltage applied to the primary winding is intermittent, and the voltage generated in the positive feedback winding wound around the transformer is applied to the base of the transistor to generate self-excitation. In a base current supply method in a ringing current converter configured to output a transformed voltage from a secondary winding of a transformer, the current transformer is connected in series to the primary winding; a current transformer drive circuit that drives the transistor by applying a voltage generated by the current transformer in a superimposed manner to the base of the transistor; The present invention is characterized by comprising a current transformer drive circuit abnormal oscillation prevention circuit that eliminates the current superimposed on the base of the transistor via the current transformer drive circuit.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams explaining the operation of the configuration of one embodiment of the present invention shown in FIG. 1, and FIG. 4 is another embodiment of the present invention. An example configuration diagram is shown.

In the figure, 1 is a current transformer drive circuit, 1-1 is a current transformer CT ₁ , 2 is a control circuit, 3 is an RCC transistor T ₁ , 4 is a voltage sense circuit, R ₁ to R ₃ are resistors, C ₁ to C ₄ represent capacitors, and D ₁ to D ₄ represent diodes.

In Fig. 1, a current transformer drive circuit 1 is for supplying a current in a manner that superimposes the current from the positive feedback winding _N2 supplied to the base of the transistor _Tr2 . It is. The transistor Tr ₁ , the resistor R ₂ , and the capacitor C ₃ in the current transformer drive circuit 1 are designed to prevent abnormal oscillations that occur when the power supply voltage E _io drops, etc., as will be described later with reference to FIG. This is provided to prevent this. The configuration and operation will be explained in detail below.

Transistor Tr ₂ in Figure 1 is an RCC transformer.
This is for intermittently applying the power supply voltage E _io to the primary winding N ₁ of T ₁ 3. Then, the voltage that is transformed by the RCC transformer T ₁ 3 and generated in the secondary winding N ₃ is rectified and smoothed by the diode (rectifier) D ₄ and the electrolytic capacitor C ₄ , resulting in a DC voltage E ₀
is output as The value of the output DC voltage E ₀ is detected by the voltage sense circuit 4 and supplied to the control circuit 2 in a negative feedback manner. For this reason,
The control circuit 2 controls the supply time of the base current supplied to the base of the transistor Tr ₂ so that the value of the DC voltage E ₀ detected by the voltage sense circuit 4 becomes equal to a predetermined value.

On the other hand, the base current supplied to the base of the transistor Tr ₂ firstly transfers the voltage generated in the secondary winding N ₂ of the RCC transformer T ₁ to the resistor R ₁ and the capacitor C ₁
is supplied in the form of positive feedback. By supplying the base current to the base of the transistor Tr ₂ in the positive feedback mode, the collector current I _C increases between the primary winding N ₁ of the RCC transformer T ₁ 3 and the primary winding of the current transformer CT ₁ 1-1. Flows to _Na . Therefore, secondly, the voltage generated in the secondary winding N _b of the current transformer CT ₁ 1-1 is controlled by a diode D ₂ , capacitors C ₂ , C ₃ , transistor Tr ₁ and resistor R ₂ . Transistor Tr ₂
The base current is supplied by applying the current to the base of the base in a so-called superimposed manner. As above, RCC transformer T ₁
A current transformer CT 1 is connected in series to the collector side of the transistor Tr 2, and the voltage generated in the secondary winding N ₂ of the transistor Tr ₂ is applied to the base of the transistor Tr ₂ in a positive feedback manner to supply the base current _.
Tr ₂ which also carries the voltage generated by 1-1
Since the base current is supplied by applying it to the base of the transistor, it improves the power conversion efficiency and improves the power conversion efficiency.
Abnormal oscillation is prevented by a switching circuit (abnormal oscillation prevention circuit) consisting of Tr ₁ , capacitor C ₃ , and resistor R ₂ .

Next, the operation of the configuration shown in FIG. 1 will be explained in detail using the waveform diagram shown in FIG. 2.

The current i _R1 in FIG. 2 is the current flowing to the base of the transistor Tr ₂ , and the voltage generated in _{the positive feedback winding N 2 in} FIG _.
It is supplied by applying it to the base of transistor Tr ₂ via Tr 2 .

In the figure, the current i _e2 is the current flowing through the emitter of the transistor Tr ₂ .

The current i _c1 in the figure is a current flowing from the base of the transistor Tr ₂ to the emitter as shown in the figure by the current transformer drive circuit 1.
It is supplied by the voltage generated by the secondary winding N _b of the current transformer CT ₁ 1-1.

In the figure, V _CE of transistor Tr ₂ is transistor Tr ₂
shows the voltage generated between the collector and emitter of Next, the operation will be explained.

At the time in FIG. 2, the current i _R1 is supplied to the base of the transistor Tr ₂ as shown, so the collector and emitter of the transistor Tr ₂ are in a conductive state, and V _CE becomes zero potential. and,
A current i _e2 is gradually increasing at the emitter of the transistor Tr ₂ .

At the time in the figure, the current i _c1, that is, the current from the current transformer drive circuit 1, is supplied from the base of the transistor Tr ₂ to the emitter direction, so the current i _e2 flows through the so-called transistor Tr 2 as shown in the figure.
It will be supplied in a manner that exceeds the saturation current I _TH of Tr ₁ . The value of the saturation current I _TH can be set to a desired value by inserting a bias diode in series with the resistor R ₂ in FIG.

At the time in the figure, both ends of the control circuit 2 are short-circuited based on the signal from the voltage sense circuit 4, so
The current i _R1 flows in a negative direction in a manner of charging, and the value of the current i _C1 becomes zero. Then, the transistor Tr ₂ becomes non-conductive and V _CE becomes a predetermined voltage as shown in the figure. Also, the current transformer
A back electromotive voltage is generated in the secondary winding _Nb of CT ₁ 1-1, but it is consumed through the diode D ₁ and is reset. By continuing the oscillation as shown in the figure repeatedly as described above, a predetermined voltage is generated on the secondary side. In addition, if the load on the secondary side is light and the collector current of transistor Tr ₂ does not reach the saturation value I _TH , the current transformer
The power generated in the secondary winding N _b of CT ₁ 1-1 is consumed by charging and discharging capacitors C ₂ and C ₃ , but since the current flowing in the primary winding N _a is small,
Losses are small.

Next, using FIG. 3, the transistor in FIG.
The operation of the abnormal oscillation prevention circuit composed of Tr ₁ , resistor R ₂ and capacitor C ₃ will be explained.

Generally, the current flows to the collector side of the transistor.
By connecting transformers in series and using the voltage generated in the secondary winding due to the collector current flowing through the primary winding of the current transformer, the direction from the base to the emitter of transistor Tr ₂ as shown in Figure 1 is applied. In other words, when current is forced to flow, the RCC transformer T ₁ 3 and the current transformer in Figure 1
The time relationship between the currents and CT ₁ 1-1 becomes a problem, and abnormal oscillations sometimes occur. The operation in the configuration shown in FIG. 1 without the abnormal oscillation prevention circuit will be described below, and then the operation in the case where the abnormal oscillation prevention circuit is added will be described in detail.

First, when the power supply voltage E _io decreases, the duty of maintaining conduction by transistor Tr ₂ increases, the oscillation frequency decreases, and the output voltage E ₀
is controlled to keep it constant.

Second, in the first case, the current transformer CT ₁
Abnormal oscillation does not occur when the current transformer CT 1 1-1 is not saturated and the reset (discharge) of the current transformer CT ₁ 1-1 is completed within the period in which the transistor Tr ₂ is kept non-conductive.

Thirdly, when the power supply voltage E _io further decreases, the current transformer CT ₁ 1-1 tries to forcefully supply the base current to the base of the transistor Tr ₂ . Then, when the current transformer CT ₁ 1-1 is saturated, the supply of the base current is stopped, so the transistor Tr ₂ becomes non-conductive, and the output voltage E ₀ decreases.

Fourthly, at the third point in time, the duty of conducting is much greater than 50%, so the current transformer CT ₁ is sufficiently shortened to 1-1 during the period when transistor Tr ₂ is non-conducting. There may be cases where it is not possible to reset. and,
When the RCC transformer _T13 is reset,
A current is supplied to the base of the transistor Tr ₂ by positive feedback, and the transistor Tr ₂ becomes conductive. However, since no current is supplied to the base from the current transformer CT ₁ 1-1, a small current flows through the transistor Tr _2. , and immediately becomes non-conductive.

Fifth, the small oscillation continues until the reset of the current transformer CT ₁ 1-1 is completed, but when the current transformer CT ₁ 1-1 is reset and the transistor Tr ₂ becomes conductive. , a large collector current flows because the base current is supplied until the current transformer CT ₁ 1-1 is saturated.

In the third to fifth operations explained above,
A large collector current flows in a relatively large cycle, and the cycle changes further due to fluctuations in the power supply voltage E _io , resulting in abnormal oscillation noise. The transistor Tr ₂ in this state
The V _CE and I _C waveforms are shown in Figure 3.

Next, the reason why the abnormal oscillation does not occur when a switching circuit (abnormal oscillation prevention circuit) consisting of the transistor Tr ₁ , the capacitor C ₃ and the resistor R ₂ in FIG. 1 is added will be explained.

(A) The first and second operations described above are the same, so their explanation will be omitted.

(B) If the power supply voltage E _io decreases further, the voltage generated in the positive feedback winding N ₂ shown in Figure 1 is transferred to the resistor R ₁
and transistor Tr ₂ through capacitor C ₁
It is not possible to supply a current up to the current value I _TH in the current i _e2 in FIG. 2 by simply supplying the base current by applying it to the base of Moreover, due to the abnormal oscillation prevention circuit, if the current i _e2 does not exceed the current value I _TH , the current transformer
Since the base current is not supplied from CT ₁ 1-1 in a superimposed manner, abnormal oscillation does not occur. At this time, the current transformer
With the high voltage generated in the secondary winding N _b of CT ₁ 1-1,
It is necessary to properly choose the values of capacitors C ₂ and C ₃ so that transistor Tr ₁ is not destroyed.

FIG. 4 shows a block diagram of another embodiment of the saturation type. In the saturated type, diodes D ₂ and D ₃ are removed from the unsaturated type shown in the first diagram, and the transistor Tr ₂ becomes saturated during operation. The other configurations and operations are the same as those shown in FIG. 1, so explanations will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, in a circuit that intermittently applies a DC voltage to the primary winding of a transformer and obtains a transformed voltage to the secondary winding, the DC voltage is intermittently applied to the primary winding. Applying current to the circuit
Since a transformer is used and a circuit that prevents abnormal oscillation is adopted, power conversion efficiency can be improved and operation can be stabilized.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams explaining the operation of the configuration of one embodiment of the present invention shown in FIG. 1, and FIG. 4 is another embodiment of the present invention. Example Configuration Diagram: FIG. 5 shows a configuration diagram of a base current supply system in a conventional ringing-choke converter. In the figure, 1 is a current transformer drive circuit, 1-1 is a current transformer CT ₁ , 2 is a control circuit, 3 is an RCC transformer T ₁ , 4 is a voltage sense circuit, R ₁ to R ₃ are resistors, C ₁ to C ₄ represent capacitors, and D ₁ to D ₄ represent diodes.

Claims (1)

[Claims] 1 A transistor is connected to the primary winding of the transformer, and the voltage applied to the primary winding is intermittent, and the voltage generated in the positive feedback winding wound around the transformer is applied to the base of the transistor to generate a self-energizing system. A ringing converter configured to operate in an excited mode and output a transformed voltage from the secondary winding of the transformer.
In a base current supply method in a Chi-Yoke converter, a current transformer is connected in series to the primary winding, and the voltage generated by the current transformer is applied to the base of the transistor in a superimposed manner to drive the converter. current
a current transformer drive circuit that eliminates the current superimposed on the base of the transistor via the current transformer drive circuit when a current below a predetermined threshold is supplied to the primary winding; A base current supply method for a ringing-choke converter characterized by comprising an abnormal oscillation prevention circuit.