DE2728468A1 - Digital power controller esp. for heater loads - has A=D converter and zero voltage switches controlling power to binary stepped heating elements - Google Patents

Abstract

The power controller provides very fine incremental power adjustment without mains interference even with high powers. If is esp. suitable for controlling heaters. The controller consists of an input unit (1) to which desired temperature, actual temperature, heating rate (temp. rise with time) and correction rate (follow-up speed) signals are fed. The analogue signals from the input unit are converted to digital form in an A/D converter (2) having an 8-bit output. These outputs are coupled via opto-insolators (3) to individual zero voltage switches (4). These in turn control the amount of power fed to the individual heating elements (5). The zero voltage switches switch the AC power on and off only at the zero-crossing instant and the power is supplied in the form of bursts of a few cycles at a time.

Description

fisar graded power regulator state of the techuunik äremul mesh Device, e.g. vine-closing electric motors, the sesölse bnexgie itself zuel, others are fully dependent on a Bosierasg from the outside (e.g. thermostats). An "off" switch is to be axed as a next switch, which is triggered by an actuator What is affected is what is influenced by a sensor (Lewelkreis). This arrangement, see Fig.1, leads uaturgesäü to a velle switching on and off of the entire performance, what causes the Isl-Tehperatsr to commute around the Sollvert (Fig. 5 and 6).

Ed the dusting liquor and heat conduction pipes at a higher temperature wschsen, vereticht sinch the ratio of the switch-on time to the switch-off tent (Ant.5). Thereby Thermestalem were developed, which Slttels Stellertransfersator the agitation reduce in order to achieve the same switch-on and switch-off times (Fig. 2) the amplitudes of the sawtooth vibrations are reduced by the setpoint, irdem the heating power divided into a base and a cusp (Fig. 3). From the thermal The sliding adjustment of the heating voltage through is to be regarded as jdcal a variable transformer (Fig.4). Unfortunately it is here at Höborer Leistuegen un site heavy and bulky euro direction, which with additional electromechanical Works well and reacts sluggishly.

Another option is the connection of resistors (Fig.

7), which can be changed manually, mechanically or electrically (sotentiementer, tube, Trausistor). It leads to Pv losses that are up to 25.6 the maximum useful power PN (Fig. 9). This could also be done digitally Carry out if the considerable resistance of the heating elements did not have a disruptive effect (Fig.8).

Nenere developments, which the desired, sliding change of the Effecting performance (Fig.10), but started with the phase limit controller of higher power the sinusoidal shape of the mains current and thus also connected at the same time Consumers, such as measuring and analysis devices, are sensitive to interference (Fig. 11). This disadvantage avoids the zero voltage switch, which the mains alternating voltage only momentarily of the zero crossing on or off, which puts the required power in the form longer or shorter sequences of sinusoidal oscillations is assigned (Fig. 12). However here too there are often disturbances due to "flickering" (= very brief switching on and off full power).

Task It is to unseal a power regulator, which has a sebr fine gradation of the delivered power allowed and thus to the supply probe Arrangement can be optimally adapted. There must be no interference in the power supply network arise, even if the dismantled services have been high, solution if a analog dosing is not practicable, a digital graduation is sufficient, as long as it is only fine, i.e. the smallest unit only 1% or 1% of the maximum Weries.

Since this cannot be achieved using series resistors (Fig.8), the heating element must be broken down into a number of binary elements graded in performance; (5) in Fig. 13. This can be done via optocoupler (3) and zero voltage switch (4) are switched, which in turn are starred by an analog-to-digital converter (2) will.

The A / D converter receives its analog signal from the temperature sensor (Tist) and of preselected voltages (TsAll, heating rate for temperature programs, correction rate) via a tax unit (1).

The setting of the control unit and thus the weighting of this Sizes depend on the thermal properties of the device to be controlled (water value, Thermal insulation). The arrangement shown in Fig. 13 provides a gradation of the Heating output to 0.4% of the? Axiinal output (8 bit), to Fig. 13: Toll specified Target temperature, Tis measured actual temperature, H.R. Heating rate (temp. Increase per time), k.H. Correction rate (speed of tracking), t: control unit; 2: A / D converter ; 3: optocoupler ": zero voltage switch; 5: heating elements.

L e r s e i t e

Claims (1)

Dinar graded performance regulator P a t e n t a n s p r ü c h e 1. Power regulator, characterized by the binary gradation of the power supplied by means of separating the consumer into a number of binary graded ones in terms of performance Elements, 2. Leistunsrsgler after cont. 1, marked by controlling the condemners Via low voltage switch and a suitable analog-to-digital converter. 3. Power regulator according to claims 1 and 2, characterized by a control unit, which reports an Aualogsignal from the input data, which the required Performance is prepertioral,