AT15875U1 - Converter module for the operation of lamps, with potential-separating clocked converter - Google Patents

Abstract

In one aspect, the invention provides a converter module (K), comprising: a potential-separated converter (W) clocked on the primary side by means of a switch (S), which can be supplied on the input side on the basis of an AC voltage, in particular a mains voltage, or a DC voltage and starting from its secondary side, a load (L), preferably at least one light source is operable, a control unit (SE), which is adapted to a switch-on period of the switch (S) in a feed-forward operation and / or using a recycled To regulate the measuring signal. For a certain period of time or a certain number of switching cycles after the DC or AC voltage is switched on, a constant or variable limitation of the switch-on time duration of the switch (S) can be predetermined.

Description

description

CONVERTER MODULE FOR THE OPERATION OF LUMINAIRES, WITH A POTENTIAL-DISCONNECTING CLOCKED TRANSFORMER The invention relates to a converter module with a clocked converter, in particular with a flyback converter (flyback converter, also step-up converter), as it is e.g. for the operation of illuminants (LEDs, Oleds, gas discharge lamps ...). The invention relates in particular to the use of potential-isolating clocked converters in such a converter module, which are clocked by a clocked semiconductor switch which is designed as a transistor, preferably as a FET transistor (e.g. MOSFET).

[0002] DE 10 2010 064 032 A1, which describes the use of a flyback converter in a converter module for gas discharge lamps, can be regarded as a starting point for the invention. EP 0 470 750 A2 should also be mentioned, in which the use of a flyback converter in a power supply unit is described.

The potential-isolating clocked converter divides the converter module into a primary side and into a potential-separated secondary side. A supply voltage / a supply current is supplied to the converter module on the primary side, which / corresponds in particular to the mains supply or is derived therefrom. Alternatively, there can be a DC supply. In particular, the supply voltage / the supply current is a DC voltage / a DC current or an AC voltage / an AC current (direct or alternating voltage / current).

Starting from the secondary side of the converter module, a load, in particular at least one lamp, is then supplied. The converter module is preferably arranged in a ballast or is part of the ballast.

The floating clocked converter of the converter module transmits power from the primary to the secondary side. With reference to FIG. 1, the basic mode of operation of a converter, as it is mainly considered below, is to be explained. When the switch is closed (Fig. 1, top), a primary winding of the converter is connected directly to the supply voltage / current. The primary current and magnetic flux in the converter increase and energy is stored in the converter. The voltage induced on the secondary side is then negative, so that a diode on the secondary side blocks. A secondary-side capacitance supplies energy to the load.

When the switch is opened (Fig. 1, below), the primary-side current and the magnetic flux drop. The voltage induced on the secondary side is then positive, and the diode no longer blocks, so that the current can flow out of the converter. The energy provided by the converter on the secondary side charges the capacitance and supplies the load.

To control the transmitted power, the converter module also has a control unit which, for example, as a proportional controller (P controller), proportional-integral controller (PI controller), proportional-integral-differential controller (PID- Controller) and / or proportional-differential controller (PD controller). An integrated circuit (IC, ASIC) or a microcontroller can also be used as the control unit. A load is therefore operated on the converter module, which is operated with power from the secondary side of the converter.

After switching on or resetting the supply voltage / the supply current, the control unit of known converter modules will first try to regulate as quickly as possible to a setpoint for the power output, which is provided for the load, during a starting phase. Thus, the switch-on time of the converter switch (FET, MOSFET, ...) is selected to be long enough to achieve high energy transmission via the converter.

However, this means that during this starting phase, a very high current flows through the converter switch. One of the reasons for this is that capacities on the secondary side of the converter, but also, for example, chokes, must first be charged and / 6

AT15 875U1 2018-07-15 Austrian patent office therefore there is a high power requirement on the secondary side.

This can lead to an avalanche / avalanche breakthrough effect ("avalanche effect," avalanching, avalanche multiplication or carrier multiplication) on the converter switch, which can damage or destroy the silicon structure of the converter switch, that is to say the semiconductor switching element can subsequently lead to a failure of the switch and thus of the converter module. As stated, this high current is caused by the fact that after the supply voltage / supply current has been switched on, a very high current is initially requested from the secondary side of the converter in order to bring the secondary side into a desired operating state.

[0011] During an avalanche / avalanche breakdown effect, a large amount of energy is also converted into thermal energy.

The aim of the invention is therefore to provide a solution that allows operation of the converter module and at the same time prevents damage or destruction of the converter switch, in particular by preventing an avalanche / avalanche breakdown effect from occurring during the Phase comes immediately after switching on the supply voltage / supply current.

The solution according to the invention is implemented by a device and a method as claimed in the independent claims. Further development of the invention is the subject of the dependent claims.

In one aspect, the invention provides a converter module, comprising: a potential-isolated converter clocked on the primary side by means of a switch, which can be supplied on the input side starting from an AC voltage, in particular a mains voltage, or a DC voltage and starting from the secondary side thereof Last, preferably at least one lamp can be operated, a control unit which is designed to regulate a switch-on time of the switch in a feed-forward mode and / or using a returned measurement signal. For a certain period of time or a certain number of switching cycles after switching on the DC or AC voltage, a constant or variable limitation of the switch-on period of the switch can be specified. “Restriction means that the limited switch-on time is shorter than that which can be set as the maximum switch-on time (tone-time) after the start phase.

[0015] The regulation can be a linear or ramp-like increase in the switch-on time.

[0016] The control unit can change the switch-on time period within the specific time period at equal or variable intervals.

The measurement signal can be a supplied parameter, in particular a feedback signal from the secondary side of the converter.

The measurement signal can be a current / voltage at the load and / or a parameter reflecting the type of the connected load.

The specific time period can be 2 to 12 ms, in particular 4 to 10 ms.

The control unit can increase the switch-on time by a fixed or variable value.

The control unit can increase the switch-on time period after 1 ms by 1 ps.

The control unit can determine the switch-on time based on a stored function and / or a look-up table.

In a further aspect, the invention provides a ballast for light sources, in particular for LEDs, with a converter module as described above.

The invention also provides a lamp with a ballast as described above.

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In yet another aspect, the invention provides a method for operating a converter module, wherein a control unit, a switch-on period of a potential-isolated converter clocked on the primary side by means of a switch, which on the input side starts from an AC voltage, in particular a mains voltage, or one DC voltage can be supplied and, starting from its secondary side, controls a load, preferably at least one light source, in feed-forward mode and / or using a returned measurement signal, and for a certain period of time or a certain number of switching cycles after switching on the DC or AC voltage is given a constant or variable limitation of the switch-on time.

The invention will now be described with reference to the figures. 1 shows schematically a basic structure of a clocked electrically isolated switch;

and Figure 2 schematically shows a converter module according to the invention.

In the present case, switching on means an interruption of the supply voltage / the supply current of the converter module, as it is e.g. when a ballast is restarted or the mains voltage supply is switched on again, but the load is also restarted, i.e. of the connected illuminant occurs.

In Fig. 2, the converter module is denoted by K and the load by L. The dashed elements indicate an optional return of a parameter from the Lasst or a parameter identifying this, which can optionally, as well or alternatively be fed to the control unit from the secondary side of the converter. The potential separation by the converter is indicated in the converter by a dash-dotted line. It is clear that (e.g. in a ballast) additional modules can be connected between the mains supply and the converter module and / or between the converter module and the load. This is illustrated in FIG. 2 with interrupted connecting lines.

In most cases, the avalanche / avalanche breakdown effect occurs after switching on during a start-up phase, usually only for a few cycles, i.e. approximately in a period of 6-12 ms, in particular 8-10 ms. More specifically, the start-up phase lasts until the capacitors on the secondary side of the converter are charged and the converter has settled.

In order to avoid the avalanche effect, it is provided to implement a so-called "soft start function in the control unit, i.e. the control unit controls the converter switch in a special way during the start-up phase.

The essence of the invention is now during the start-up phase in particular the switch-on time (tone-time), i.e. to change the time in which the converter switch is switched on or switched on.

In known converter modules, for example, the T _on time of the converter switch would be set to a fixed value, for example 4 microseconds (ps). To now avoid the avalanche or avalanche breakthrough effect, the invention provides for the T _on time to be initially selected to be low or limited to a low value during the start-up phase and then to be increased successively over the duration of the start-up phase.

For example, instead of a period of 4 ps, a period of 1 ps can first be selected. The T _on time can then be increased at fixed or variable intervals. For example, at intervals of one millisecond (ms), the T _on time can be increased by at least one microsecond until a maximum T _on time for the converter switch is reached. Overall, a T _on time of 1-12 microseconds, in particular in the range of 4-10 microseconds, can thus be set in the start-up phase. The time for the start-up phase can be permanently stored in the control unit.

However, it is also possible that the duration of the start-up phase and / or the switch-on time 3/6

AT15 875U1 2018-07-15 Austrian patent office duration is selected as a function depending on, for example, a measured value or parameter supplied to the control unit, for example one returned from the secondary side

Parameter. In particular, the time intervals at which the switch-on time is increased can also be selected dynamically.

It is also possible that a table in the form of a look-up table is stored in the control unit, and thus time intervals for increasing the switch-on time or the duration for the start-up phase are selected depending on a parameter supplied to the control unit. For example, a converter module can detect a connected load by means of a detection function, not shown. If information about the connected load is therefore transmitted to the control unit, the start-up phase or the switch-on time can be set depending on this.

[0038] The control unit can also regulate the switch-on period in feed-forward operation, in particular without a measurement signal or parameter being fed back to the control unit. For example, the control unit can recognize that the supply voltage / supply current has been switched on. From this detection, the control unit can then regulate or limit the switch-on time for a specific time, and / or change it as a function of time or on the basis of data stored in a table.

The sequential increase in the switch-on time can also avoid a large voltage drop on the secondary side of the converter, since the control of the output voltage takes place much faster.

The “soft start” function thus implemented avoids the avalanche effect or the avalanche breakthrough effect and also makes it possible to carry out the control with a controller that only allows a relatively low control speed. Otherwise, ie without the "soft start function", a more expensive controller with higher speed would be necessary in order to achieve a reduction in the avalanche effect or the avalanche breakdown effect with a constant T _on time.

The invention has the further advantage that, with a corresponding setting and change in the switch-on time during the start-up phase, the converter switch can also be selected such that it is in principle designed for a lower power (ie, for example, a smaller transistor can be used ). Since high current flows during the start-up phase are avoided by the control method according to the invention, these smaller switching elements can be used and there is no fear of an avalanche effect or avalanche breakdown effect.

In summary, it can be said that the solution according to the invention during the starting process / during the startup phase limits the maximum switch-on time of the converter switch, so that in this phase the maximum current flowing through the converter switch is also limited. More specifically, however, there is no fixed limit on the switch-on time of the converter switch, but the limit for the maximum switch-on time of the converter switch is increased in a ramp-like or linear manner after switching on / after the mains reset in the start-up phase.

Overall, the duration of the start-up phase, i.e. the switch-on time limit for the converter switch in the range of several switch-on cycles (for example 5-15, in particular 7-12 switch-on cycles).

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Claims (10)

Expectations 1. converter module (K) comprising: - A potential-isolated converter (W) clocked on the primary side by means of a switch (S), which can be supplied on the input side from an AC voltage, in particular a mains voltage, or a DC voltage, and a load (L), preferably at least one, from its secondary side Illuminant can be operated, - A control unit (SE), which is designed to regulate a switch-on period of the switch (S) in a feed-forward mode and / or using a returned measurement signal, and for a specific period of time or a specific number of switching cycles after switching on the DC or AC voltage is subject to a constant or variable limitation of the switch-on time (S). 2. Converter module (K) according to claim 1, wherein the control is a linear or ramp-like Increase of the switch-on time. 3. Converter module (K) according to claim 1 or 2, wherein the control unit (SE) changes the switch-on time period within the determined time period at the same or variable intervals. 4. Converter module (K) according to one of the preceding claims, wherein the measurement signal is a supplied control parameter, in particular a feedback signal from the secondary side of the converter (W). 5. Converter module (K) according to claim 4, wherein the measurement signal is a current / voltage at the load (L) and / or a type reflecting the type of the connected load (L). 6. Converter module (K) according to one of the preceding claims, wherein the specific time period is 2 to 12 ms, in particular 4 to 10 ms. 7. Converter module (K) according to one of the preceding claims, wherein the control unit (SE) increases the switch-on time by a fixed or variable value. 8. Converter module (K) according to one of the preceding claims, wherein the control unit (SE) increases the switch-on time period after 1 ms by 1 ps. 9. Converter module (K) according to one of the preceding claims, wherein the control unit (SE) determines the switch-on time period on the basis of a stored function and / or a look-up table. 10. Ballast for lamps, in particular LEDs, with a converter module (K) according to one of the preceding claims. 1 sheet of drawings 5.6 AT15 875U1 2018-07-15 Austrian patent office Transducer switch switched on Transducer switch switched off Fig. 1 Fig. 2 6.6