JPS62285662A - Power converter - Google Patents

Abstract

PURPOSE:To limit currents flowing through an inductor without varying reference oscillation frequency, and to prevent overcurrents in case of a deep drooping by operating a switching element by reference oscillation frequency for some period and stopping the switching element for some period. CONSTITUTION:The peak value of currents flowing through an inductor 6 detected by a current detector 16 does not reach the first reference value of a comparison circuit 14 under a stationary state. Consequently, a control signal from a control circuit 11 is inputted to a drive circuit 12, and the drive circuit 12 drives a transistor 3. When the short circuit, etc. of an output are generated and the peak value of currents flowing through the inductor 6 detected by the current detector 16 reaches the first reference value of the comparison circuit 14, a stop-signal generation circuit 13 outputs a stop signal to the drive circuit 12, and the drive circuit 12 stops the drive of the transistor 3. When currents detected by the current detector 16 reach the second reference value of the comparison circuit 14, the drive circuit 12 drives the transistor 3 again.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application] The invention connects a DC paper source, a transformer, and a switching element in series, and outputs the acceleration time of the switching element. The present invention relates to a power conversion device that obtains a stable output voltage by controlling the voltage according to deviation from a reference voltage.

[Conventional technology]

Technology that connects a DC power source, a transformer, and a switching element in series and periodically turns on and off the switching element to convert power has high power conversion efficiency and has been used in various fields for a long time.

FIG. 6 is a diagram for explaining such a conventional power conversion device. In the figure, 1 is a direct current source, 2 is a primary winding MN, and a transformer having a secondary winding N2', 6 is a transistor which is a switching element, 4 is a rectifier, and 5 is a non-conducting transistor 6. This is a flywheel guide designed to release energy by the load 7 so that the residual energy accumulated in the inductor B does not generate high pressure υ. 8 is a flat f# circuit consisting of an inductor 6 and a capacitor 9, 1o is a reference oscillator, 11 is a control circuit,
12 is a drive circuit.

Next, the operation will be explained. First, the transistor in the drive circuit 12 begins to operate in a switching manner, and the voltage E1 of the @fL power supply 1 is periodically applied to the primary winding N1 of the transformer 2. As a result, a voltage is generated in the secondary winding 1RN2, and this spiral voltage flows through the rectifier 4, is smoothed by the smoothing circuit 8, and is supplied to the load 7. The voltage E2 applied to the load 7 is compared with the reference voltage in the control circuit 11, and the deviation is amplified and the entire pulse width of the reference pulse from the reference oscillator 10 is changed and sent to the drive circuit 1 as the control signal S1.
2, the drive circuit 12 controls the conduction time of the transistor 6 and stabilizes the output voltage. However, when the output is overflowing, it has a drooping function, and when there is a particularly deep drop (output short circuit, etc.), it detects a drop in the output voltage and uses this to adjust the reference oscillation frequency from the reference oscillator 10. This prevents an excessive current from flowing into the transistor 3' and prevents the transistor 6 from being destroyed.

[Problem that the invention seeks to solve]

However, in the conventional power conversion device, since the reference oscillation frequency from the reference oscillator 10 is lowered during deep droop, the device becomes unstable and tends to malfunction.

[Means for resolving issues]

In order to solve the above problems, the present invention provides a series connection circuit consisting of a DC power supply, a transformer, and a switching element, a drive circuit for driving the switching element, a rectifier, and a smoothing circuit consisting of an inductor and a capacitor. and a control circuit that performs negative feedback control of the conduction time of the switching element according to the deviation of the output voltage from a reference voltage, and is configured to maintain a stable output voltage. a '1-area current output that detects the flowing current;
When the current detected by the current detector reaches the first base value, a signal to stop driving the switching element is generated, and the current detected value becomes lower than the first reference value. When the second reference value, which is a low value, is reached, the signal t-
A power conversion device characterized by a stop signal generation circuit that disappears! 1 [Operation] Since the invention has the above-mentioned configuration, by operating the switching element at the reference oscillation frequency for a certain period and stopping it for a certain period, the reference oscillation frequency can be adjusted. ′l! flows into the inductor without changing ′l! [Embodiment] FIGS. 1 and 2 are diagrams for explaining an embodiment of the present invention. In FIG. 1, 13 is a stop signal generation circuit consisting of a comparison circuit 14 and an amplifier circuit 15, and 16 is a current flow detector that detects the current 't flowing through the inductor 6t.
' Also, in Fig. 2, VFD is the voltage of the flywheel diode 5, L is the flow through the inductor 6: rt,
6 #L style.

I will briefly explain the operation. First, in a steady state, the current I flowing through the intactor 6 is detected by the current detector 16.
The peak value of the first group 111111.
However, as shown in FIG. 2(a), since the first reference value is not exceeded, the stop signal generating circuit 12 does not generate the stop signal s2. Therefore, the drive (b) path 12 inputs the control signal S1 from the control circuit 11 to drive the transistor 6. Next, a short circuit or the like occurs on the output side, and the current I flowing through the inductor 6 is detected by the current detector 16.
As shown in FIG. 2(b), the peak value of L is
40 When the first reference value is reached, the deviation value is
The stop signal generation circuit 13Fi stop signal 82't- is amplified by 5 and output to the drive circuit 12, which stops driving the transistor 6. Next, the current flows through the inductor 6 detected by the current detector 16 (comparison (b) where the flow decreases and is lower than the first reference value as shown in FIG. 2(b)). When the second reference value of path 14 is reached, the stop signal generating circuit 16 completely stops outputting the stop signal S2 to the drive circuit 12, so that the drive circuit 12 starts driving the transistor 3 again.

In this way, in the present invention, the reference number of oscillations from the reference oscillator 10 remains constant, and the prevention of tailing at the time of drooping is performed by a completely separate control system, so that there is no interference and the operation is stable. 9. Comparison circuit 1 of stop signal generation circuit 13
4 also includes hysteresis, which prevents the power converter from restarting unless the current flowing through the inductor 6 decreases, resulting in a stop period in the power converter, which equivalently lowers the frequency. Furthermore, since the current flowing through the inductor 6t is detected, an instantaneous response is possible. Therefore, from the above, the switching element 3t can be reliably protected in the event of a load short circuit.

〔Effect of the invention〕

As mentioned above, Book 5@Akira includes a series connection circuit consisting of a DC power supply, a transformer, and a switching element, a drive circuit that drives the switching element, a 1M current transformer, a smoothing circuit consisting of an inductor and a capacitor, A control circuit that performs negative feedback control according to the deviation of the total output voltage from the reference voltage during the conduction time of the switching element, and stabilizes the output direct voltage t.
- A current detector detects the current flowing through the inductor, and a current detector detects the current flowing through the inductor, and when the detected value reaches the first reference value, the current detector detects the current flowing through the inductor. , generating a signal to stop the driving of the switching element, and disappearing the signal when the first flow detection value reaches a second reference value that is lower than the tenth reference value; This is a single force conversion device characterized by being fully equipped with a signal generation circuit. Does the present invention have such characteristics? Therefore, instantaneous response is possible, and a stop period can be provided for the power converter, and the frequency can be equivalently lowered completely.

Therefore, the switching element can be reliably protected in the event of a load short-circuit or the like.

[Brief explanation of the drawing]

1 and 2 are companion diagrams for explaining one embodiment of the present invention, and FIG. 6 is a diagram for explaining the entire conventional power conversion device. 1... DC power supply 2... Transformer 6... Switching cable 4... Rectifier 5... Flywheel diode 6... Inductor 7... Load 8... Flat l
l1t circuit 9...Capacitor 10...Reference oscillator 11...Control circuit 12...Drive circuit 16...Stop signal generation circuit 14...Comparison circuit 15...Amplification circuit 16...? 4-flow detector patent applicant Origin Hikiki Co., Ltd. Nichifu Telephone and Telephone Co., Ltd. Figure 3

Claims (1)

[Claims] A series connection circuit consisting of a DC power supply, a transformer, and a switching element, a drive circuit that drives the switching element,
It has a rectifier, a smoothing circuit consisting of an inductor and a capacitor, and a control circuit that performs negative feedback control of the conduction time of the switching element according to the deviation of the output voltage from the reference voltage, so as to obtain a stable output voltage. In the power conversion device, a current detector detects direct current flowing through the inductor, and when a current detection value detected by the current flow detector reaches a first reference value, stopping driving of the switching element. A stop signal generation circuit that generates a signal and eliminates the signal when the detected current value reaches a second reference value that is lower than the first reference value. conversion device.