DE102004019305A1 - Impedance component for mains supply has adjustable impedance to supply increasing current to an additional user - Google Patents

Abstract

An impedance component for supplying a constant mains current to a user (R3) comprises means of changing the impedance to supply at least one further user (K1) having a switch with contacts (SK1) to change the impedance of the capacitor part (10) and provide this user with a higher current.

Description

The The invention relates to an impedance power supply with adjustable impedance according to the preamble of claim 1.

Such Impedance power supplies are often as a capacitor power supply or resistance power supply accomplished and are used in small power electronic devices, such as e.g. Motion detectors, touch switches, Timers, etc., and a low power consumption, for example below 50mA, used. These power supplies have the advantage that They are extremely inexpensive and are easy. In addition, they have a high level of robustness against EMC interference. A disadvantage of these power supplies is the lack of galvanic Separation, whereby it is used only for fully isolated small appliances can be.

The documents DE 29 49 347 C2 . DD 257 339 A1 and DE 35 45 323 A1 each describe measures to reduce the absorbed active power. By inserting a temporary short circuit by means of a controllable switch, which is for example a thyristor or transistor, the active power consumption is reduced. However, this has the disadvantage that the apparent power increases.

The DE 199 34 850 A1 discloses a power-saving capacitor power supply that controls the ingested constant current by turning a complex resistor on or off. For this purpose, a triac is used as the switching element, which increases or decreases the complex resistance. A disadvantage can be considered in this proposed circuit variant that an additional control output to an example designed as a microcontroller control unit is required to control the triac by means of a drive circuit not described in detail or via optocouplers. Furthermore, a circuit is required, which monitors the supply voltage and turns on the triac at a detected voltage dip. As a result, the circuit complexity is increased.

Task and solution

The The object of the invention is a simply constructed impedance power supply specify which in particular a consumption-dependent controlled constant current feed allows.

Is solved this object by an impedance power supply with the features of the claim 1. Advantageous and preferred embodiments of the invention are Subject of further claims and will be closer in the following explained. The wording of the claims is by express Reference made to the content of the description.

The Impedance power supply according to the invention is suitable especially for Circuits in which in a first mode of operation, a control circuit permanently with a constant supply current with a minimum value must be supplied and in a second mode, the control circuit and an additional one Consumer in the form of a switching means with a higher constant Supply current must be supplied. According to the invention changed switchable consumers themselves the impedance of the impedance power supply via a existing switching contact, so that the constant supply current on the needed higher Value is set. Because the impedance of the power supply is automatic with the switching of the extra Consumer changed is, the supply voltage must not be monitored. This eliminates one Circuit for evaluating the supply voltage. In addition, in the control circuit no additional Output control terminal and / or means for controlling the impedance change be provided. As a result, the solution according to the invention reduces the Circuit complexity of the impedance power supply. It is preferred when switching on of the additional Consumer lowered the impedance and when switching off the impedance raised again.

Of the Switchable consumers, for example, as a relay and the control circuit is designed for example as a microprocessor with external circuitry. One such relay is supplied with that in the attracted or activated Elevated condition Electricity, so to speak, by bringing the supply current to the higher value brings.

In a possible Design of the capacitor power supply is via the switching contact of the switchable Consumer an additional Impedance parallel to the previous impedance and so the Total impedance of the capacitor power supply reduced.

alternative or additionally includes the switching contact a partial impedance to the previous impedance short and thus reduces the overall impedance of the capacitor power supply.

These and other features will become apparent from the claims and from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections and intermediate headings limit the statements made thereunder not in its generality.

Summary the drawings

embodiments The invention are shown schematically in the drawings and will be closer in the following explained. Showing:

1 a circuit diagram of a conventional capacitor power supply,

2 a circuit diagram of an embodiment of an impedance power supply according to the invention and

3 a further embodiment of an impedance power supply according to the invention.

detailed Description of the embodiments

1 shows a conventional capacitor power supply according to the prior art, as it is installed in small electrical appliances that can be connected to mains voltage. The capacitor C101 forms a complex impedance, which determines the constant AC current of the circuit. A resistor R101 provides a current limit when charging the capacitor C101. A resistor R102 serves to discharge the capacitor C101. For rectification, a bridge circuit D101 is provided which, for example, is constructed as a four-diode Grätz bridge. A capacitor C102 and a Zener diode D102 are used for buffering, smoothing and voltage limiting. A resistor R103 represents a first load, such as a microcontroller, and a relay K101 represents another load, which is connectable via a transistor T101. To connect the further consumer or the relay K101, a corresponding control signal is applied to a control input A101.

The conventional Capacitor power supply is on a maximum continuous load case interpreted, that is, when switched off consumers not needed Current from the constant AC power source through Zener diode D102 is consumed. This is the total power absorbed composed of active power and apparent power, in each operating state the capacitor power supply the same size. Partially, the recorded Active power in part-load operation even greater than in full-load operation be.

How out 2 is apparent in the embodiment according to the invention, an alternating current is impressed after the application of a mains voltage U, which results from the complex series resistance of an ohmic resistor R1 and a first capacitor C1. The AC voltage is rectified by a two-way bridge rectifier circuit D1, limited by a Zener diode D2 and smoothed by a capacitor C3.

In In a first mode, the impedance power supply only supplies one as a resistor R3 shown first consumer, for example one as a microprocessor with external circuitry executed Represents control circuit, permanently with a constant supply current with a minimum Value. The complex resistance consisting of the resistor R2 and the Capacitor C1 is formed, is chosen such that the flowing constant current big enough for the consumer R3 is.

By Subject a control signal to the base of the transistor V1 via a Input terminal A1 is an additional consumer in the form of a Relay K1 switched, for example, in an application in a cooktop another heating circuit of a multi-circuit heating means of a main contact. This is also about the Circuit SL a switching contact SK1 of the relay K1 closed and another capacitor C2 is connected in parallel to the capacitor C1. So will the necessary extra Supply current for the additional consumer K1 supplied itself, so that the whole Supply current increased from the minimum value to the new value. at a possible Contact ON delay of the relay K1 should be the energy stored in the capacitor C1 big enough be to the relay K1 during the contact delay time to provide energy. After closing the switching contact SK1 is above SL the capacitor C2 in parallel with the capacitor C1. The complex resistance from the ohmic resistor R1 and the capacitors C1 and C2 dimensioned so that the required holding current for the relay K1 and the electricity for the continuous consumer R2 available be put. about an ohmic resistance R2, which between two terminals of the both capacitors C1 and C2 is looped, the capacitors Unload C1 and C2.

In an alternative embodiment, not shown, in the first operating mode of the impedance power supply, the in 2 represented capacitance C1 formed by a series circuit of two capacitors, which provide the minimum supply current. In this case, the switching contact SK1 is connected in parallel to one of the two capacitors. To increase the supply current, the switching contact of the relay is closed and the corresponding switched to the switching contact in parallel capacitor short-circuited in this embodiment. As a result, the total impedance of the impedance power supply also decreases and the supply current is increased.

In another alternative, in 3 illustrated embodiment of the impedance power supply according to the invention or the amended section with the impedances, the two capacitors C1 and C2 are replaced by the resistors R11 and R12, wherein the in 2 shown resistors R1 and R3 is omitted. In the first mode, the minimum supply current is then determined by resistor R11. In the second mode, the required higher supply current is realized by connecting resistor R12 in parallel with resistor R11, thereby reducing the overall impedance and increasing the supply current.

Furthermore, in 3 the second switching contact SK2 shown, which is included in the relay K1 and a consumer like a further heating a cooking place or the like. can switch. The second switching contact SK2 is actuated via the common connection SL 'with the switching contact SK1'. Thus, the relay K1 switches to a control command, the further heating via the second switching contact or main contact SK2, wherein for the required holding current energy is needed. This turns on the relay itself virtually by adding the power of the power supply 10 is increased by connecting the further resistor R12 in parallel by the switching contact SK1 '.

By the solution according to the invention is the complex and / or real resistance and thus the impedance of the impedance power supply changed by a switching element, preferably the switching Element of the switchable consumer itself can be, the one about existing switching contact the complex and / or real resistance switches. The circuit construction of the impedance power supply can be simplified as an additional Control output and means for monitoring the Supply voltage and for driving the switching element in the Control circuit omitted.

Claims (6)

Adjustable impedance impedance power supply providing a constant supply current having a first value for supplying at least a first load (R3) and providing the supply current with a higher value with an impedance change when at least one additional load (K1) is connected characterized in that at least one further consumer (K1) is a switching means with at least one switching contact (SK1, SK1 ', SK2), which by operation of the switching contact (SK1), the impedance of the capacitor power supply ( 10 ) Is changed so that the constant supply current to the additional supply of the at least one further consumer (K1) is adjustable to the required higher value. Impedance power supply according to Claim 1, characterized that the switching means is a relay (K1), preferably with at least a main contact (SK2) and the switching contact (SK1, SK1 '). Impedance power supply according to claim 1 or 2, characterized characterized in that the first consumer (R3) is a microprocessor is. Impedance power supply according to one of the preceding claims, characterized in that the switching contact (SK1, SK1 ') an additional parallel impedance (C2, R12) parallel to the previous impedance (C1, R11) and so the total impedance of the capacitor power supply ( 10 ) reduced for the increased value of the supply current. Impedance power supply according to one of the preceding claims, characterized in that the switching contact (SK1, SK1 ') short-circuits a partial impedance of the previous impedance (C1, R11) and thus the total impedance of the capacitor power supply ( 10 ) reduced. Impedance power supply according to one of the preceding claims, characterized in that the impedance of the impedance power supply ( 10 ) is formed of capacitors (C1, C2) and / or resistors (R11, R12).