DE10002650C2 - Circuit arrangement for reducing the active power in a stabilized DC power supply by means of a ballast capacitor - Google Patents

Description

State of the art and problem definition

In the conventional circuit technology is for a DC power supply due to space and cost reasons, often a complex series resistor (Hochspan Capacitor), the storage capacity to the required low charge voltage. The voltage of the storage capacities is stabilized at a DC voltage supply limited, otherwise the low voltage to potential the supply voltage is running high.

This limitation is i. d. R. realized by Zener diodes, which the of the downstream circuit does not need to derive power. This creates in particular dere for larger low voltages (greater than about 10 V) and downstream Circuits with larger load changes considerable active power in the zener diode. This is a significant disadvantage of prior art circuits, because with it the efficiency of the power supply is lowered and the ent standing heat has a negative impact on the environment in most applications bende circuit.

A capacitor power supply, which takes this disadvantage into account, is already out of the Where known 99/30408. So there is the power loss of the power supply reduced by the lying at the phase of an alternating voltage network capacitor against the Neutral is shorted by a thyristor when the voltage is at the off transition of the power supply exceeds a predetermined reference value.

Based on this known solution of the application is the task based, with the least possible circuit complexity such a capacitor so that both a negative, as well as a positive out output voltage is provided with independently definable levels.

Description of the invention

The circuit arrangement serves the active power of conventional, stabilized Reduce DC supplies. This is achieved by the fact that the Leakage, which is derived via the Zener diode from the storage capacity, z. B. is measured via a resistor and when a well-defined Threshold of the ballast capacitor by means of a triac to ground shorted. A short-circuited capacitor is known to produce only Reactive power (except for minimal dielectric losses) thus no heat.

The benefit of the invention lies in: For larger low voltages and at Downstream circuits with larger load changes are known to occur considerable active power in the Zener diode with the resulting disadvantages.

The drawing 1 shows a possible embodiment with triac to produce a positive and negative voltage.  

Of course, the triac can of course also be made of discrete components (Transistors with wiring) can be realized.

Explanations to drawing 1 Voltage limitation

V2 = mains voltage source
C2 = mains voltage or ballast capacitor
D5 = rectifier diode
D9 and D10 = zener diode
U1 = positive DC output voltage
C5 = storage capacity for the positive voltage
C6 = storage capacity for the negative voltage
D6 = rectifier diode
D8 = Zener diode
U2 = negative output voltage
R2 = suppressor element, preferably resistor, possibly 0 ohms
R5 = current measuring element, preferably resistance
D2 = triac

Claims (1)

1. Power supply circuit for providing a positive and negative supply chip with a ballast connected in series with the AC input capacitor (C2) whose output alternating voltage depends on the polarity of one of two half-wave rectifiers (D5, D6) for charging one each Storage capacitor (C5, C6) is supplied, wherein the output side of the ballast capacitor (C2) pending AC voltage separated for the positive and negative half wave, each with a constant vorge voltage threshold (D9, D10, R5) is compared and the capacitor (C2) output side is shorted to ground via a triac (D2), if at positive half-wave the voltage threshold is exceeded and at negative Half wave is fallen below.