JPS59181969A - Chopper circuit - Google Patents

Abstract

PURPOSE:To efficiently and accurately control a drive of a chopper circuit by providing a power source of a controller separately from of a main power source for a load, and closing and connecting the power source the controller in reverse polarity between the emitter and the base when a switching transistor of OFF. CONSTITUTION:A switching transistor Q1 in a 1-transistor chopper is supplied with a base current from a power source 3 connected between the base and the emitter. Further, the base current is applied or interrupted, and the transistor Q1 is turned ON or OFF when a transistor Q2 is turned ON or OFF, thereby controlling a discharge lamp H. At this time, the transistor Q2 is turned ON or OFF by the ON or OFF signal determined by a controller 4. The controller 4 produces the ON or OFF signal by detecting the current by a detector 9. When the transistor Q2 is OFF, the transistor Q1 is ON, and when the transistor Q2 is ON, a DC power source 2 is connected in reverse polarity between the emitter and the base of the transistor Q1, and the transistor Q1 is accordingly rapidly turned OFF.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chopper circuit that controls the power of a load using a switching transistor.

Conventional devices that control the power of loads using switching transistors include a control IC in the control circuit that drives the transistors.
Although the cost can be reduced, the voltage of the control circuit is lower than the power supply voltage, so it is necessary to lower the voltage for the control circuit by using methods such as dropping the power supply voltage with a resistor. However, there was a drawback that the loss due to resistance was large. On the other hand, even if the above-mentioned drawbacks could be solved by providing a separate power supply for the control circuit, when the switching transistor is turned off, it does not turn off immediately due to the accumulated base current, so it is difficult to turn it on and off quickly. It was not easy to do. For this reason, various measures have been taken to shorten the storage time, but it is difficult to find an accurate countermeasure, and efficient and accurate drive control is desired.

In view of the above points, the present invention provides a power supply for a control circuit that drives a switching transistor for load control separately from the main power supply for the load, and also provides a power supply between the emitter and base when the switching transistor is turned off. Connect the power supply for the control circuit to the reverse polarity, thereby -C
The present invention provides a one-stone chamber circuit that can efficiently and accurately operate a control circuit device and a switching transistor with a lower rated voltage than the main power supply L1 for the load. The configuration will be explained below using illustrated embodiments. Figures 1 to 2 all show one embodiment of the present invention, and the same reference numerals indicate the same parts in each figure.

In FIG. 1, H is a load such as a discharge lamp (HID), and 1 is a DC power supply device that serves as the main power source of the discharge lamp J.

This DC power supply device 1 includes a primary winding N on the primary side of a transformer T. , transistors Trl and Tr2, a drive circuit A, a constant power supply, and an inverter consisting of a secondary winding N1, and rectifying and smoothing the output of the secondary winding N with a rectifier D and a fundensor C to produce a discharge lamp H. It is intended to supply Qo is a switching transistor for controlling a discharge lamp connected in series between the output side of the DC power supply device 1 and the discharge lamp H; 4 is a switching transistor for controlling the discharge lamp;
This is a control circuit device that turns on and off the transistor Q.

This control circuit device 4 has a rated voltage lower than the output voltage of the DC power supply, for example, a controller having a rated voltage of 12V for a DC power supply output voltage of 120V;
It is a roll IC, and an example is TL49 manufactured by TI.
o2 (using switching mode EC for one-chip transistors like '7) and other control/role ICi (
d DC power supply provided for the control circuit device 4, a winding mjq2 provided on the secondary side of the inverter, a diode D2,
It consists of a capacitor C2 and supplies a predetermined output load to the control circuit arrangement 4 via terminals 5.6 and 7.8.

3 is a power supply between the base and emitter of the switching transistor Q1, which consists of the secondary winding 1q3 of the inverter, a diode D3, and a capacitor C3, and one end of the capacitor C3 is connected to the base of the transistor Q through the base resistor R. and the other end is connected to the emitter via the terminal 5.6. Furthermore, one end of the control circuit power supply 2 is connected to the emitter of the switching transistor Q through a terminal 5.6 so that the polarity is opposite to the emitter of the switching transistor Q, and the other end is connected to the switching transistor Q through a second transistor Q2. Connect to the base of Q-engine. The base of this second transistor Q2 is connected to the output side of the control circuit device 4, and a resistor R2 is connected between the base and the terminal 6. Reference numeral 9 denotes a detection unit for the output of the DC power supply bag @1, and when the switching transistor Q1 is turned off, the control circuit device 4 turns on the second transistor Q, and the DC power supply 2 is connected to the switching transistor Q. Make a connection between the emitter and base of the machine. In addition, C4 is a capacitor in parallel with the discharge lamp H,
D4 is a diode forming a discharge circuit for the energy stored in the choke fill L.

In the single-stone chopper device as described above, the switching transistor Q is supplied with a base current from the power supply 3 connected between the base and the emitter. Further, by turning on and off the transistor Q2, the base current is cut off, and the transistor Q is turned on and off to control the discharge lamp H. At this time, the transistor Q2 is turned on and off by the on and off signals determined by the control circuit 4. Note that the control circuit outputs on/off signals by detecting current with the detection section 9. As mentioned above, when Q2 is off, Q
When it turns on and Q2 turns on, the switching transistor Ql
Since the DC power supply 2 is connected between the emitter and the base of the switching transistor Q1 with reverse polarity, even if the base current of the switching transistor Q remains high during the storage time, the DC power supply 2 is connected between the emitter and the base of the switching transistor Q1. Since the current flows in the opposite direction between the emitter and the base through the second transistor Q2 and the switching transistor Q1, the storage time is shortened.
The switch off is completed quickly.

In the embodiment shown in the second diagram, the DC power supply 2.3 shown in the first diagram is used as a battery power supply, and in order to reduce the current flowing through the resistor R when the switching transistor Q is off, the resistor R3
is connected to the base of the switching transistor Q via the transistor Q3, and R<R3 to reduce the loss of the resistor R when the switching transistor Q1 is off, thereby reducing the loss of the resistor R1 as a whole. be.

As described above, in the present invention, the power supply 2 of the control circuit 4 is provided separately from the main power supply for the load, and the switching transistor Q
Since the power supply 2 of the control circuit described in 1) is reversely connected between the emitter and the base when the unit is turned off, the loss when it is turned off can be reduced, and the power supply for the control circuit is connected from the main power supply through a resistor, etc. Because it is not a gain, there is less loss, and switching transistors and control circuits can be driven efficiently.

This proposal is particularly effective when the main power source is several times higher than the rated voltage of the control circuit.''5 In the example described in M, the load is a discharge lamp, but it can also be applied to various types of loads. Available.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 each show an embodiment of the present invention. 1: DC power supply 2' Control circuit power supply 4 Control circuit Q1 switching transistor H: Discharge lamp 1st stroke Figure 2

Claims (1)

[Claims] 1. A DC power supply, a load, and a switching transistor connected in series between the DC power supply and the load;
A control circuit device having a discharge rated voltage higher than the voltage of the DC power supply device and driving and controlling the switching transistor, and a DC power source for the control circuit device, and when the switching transistor is turned off, the emitter and base A chopper circuit characterized in that the DC power source for the control circuit is connected in reverse polarity between the chopper circuits. 2. The chopper circuit according to claim 1, wherein the control circuit device detects the output of the DC power supply device to drive and control the switching transistor. 3. The chopper circuit according to claim 1 or 2, characterized in that the DC power supply device is an inverter.