Silicon controlled rectifier dimming system meeting EMC (Electro Magnetic Compatibility) standard

Abstract

The invention discloses a silicon controlled rectifier dimming system meeting EMC (Electro Magnetic Compatibility) standard, which comprises a driving power supply and a silicon controlled rectifier dimmer, and is characterized in that the driving power supply comprises a power supply power module, a control line, a silicon controlled rectifier follow current module, a silicon controlled rectifier sampling module, an isolation module and a dimming control module; the silicon controlled rectifier dimmer is electrically connected with one end of the control line, the other end of the control line is electrically connected with the input end of the silicon controlled rectifier follow current module, and the output end of the silicon controlled rectifier follow current module is electrically connected with the input end of the silicon controlled rectifier sampling module. The output end of the silicon controlled rectifier sampling module is electrically connected with one end of the isolation module, the other end of the isolation module is electrically connected with the input end of the dimming control module, and the output end of the dimming control module is electrically connected with the output end of the power supply power module so as to output a PWM signal to drive an LED load.

Description

Technical Field

[0001] The invention relates to the technical field of thyristor dimming, and in particular to a thyristor dimming system meeting EMC standards. Background Art

[0002] Thyristor dimming technology is mainly used for traditional incandescent lamps and halogen lamps (resistance type). Because it is purely resistive, there is no instantaneous interference when the thyristor is turned on and off. The dimming circuit is simple and easy to use. The existing thyristor dimming is for LEDs. A driving power supply must be provided in front of the LED to work properly. The thyristor dimmer is directly connected in series to the input live wire of the driving power supply, so that the thyristor cannot be compatible with the input voltage range of 100-277V and can only be used for a fixed voltage dimming range, with poor compatibility. Secondly, the input energy of the power supply is determined by the conduction angle of the thyristor dimmer. For example, if the conduction angle of the thyristor dimmer is very small, the energy input to the power supply during the entire AC cycle is very small, and the output voltage of the power supply is insufficient, which will lead to insufficient brightness or low-brightness flashing lights. Furthermore, the input sinusoidal waveform of the power supply is incomplete at any conduction angle of the thyristor. No matter it is the front or rear cut, a spike will be generated at the moment of phase-cutting conduction. This spike will generate noise and interfere with the power grid. Since the input sinusoidal waveform of the power supply is incomplete at any conduction angle of the thyristor, the PF value and harmonics of the power supply cannot reach the standard range, and the harmonics and conduction are seriously exceeded. The problem becomes more serious when the dimming brightness is lower. The input current is seriously distorted, and the harmonics and PF values ​​cannot meet the EMC standards, causing interference to the power grid. Summary of the invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a thyristor dimming system that meets EMC standards and reduces interference to a power grid.

[0004] A thyristor dimming system that meets EMC standards according to an embodiment of the present invention includes a driving power supply and a thyristor dimmer, wherein the driving power supply includes a power module, a control line, a thyristor freewheeling module, a thyristor sampling module, an isolation module and a dimming control module, wherein the input end of the power module is connected to a live wire and a neutral wire, the thyristor dimmer is electrically connected to one end of the control line, the other end of the control line is electrically connected to the input end of the thyristor freewheeling module, the output end of the thyristor freewheeling module is electrically connected to the input end of the thyristor sampling module, the output end of the thyristor sampling module is electrically connected to one end of the isolation module, the other end of the isolation module is electrically connected to the input end of the dimming control module, the output end of the dimming control module is electrically connected to the output end of the power module to output a PWM signal to drive an LED load; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module via the thyristor freewheeling module, and the thyristor sampling module can convert the dimming signal into a square wave signal to control the dimming control module to output a PWM signal.

[0005] The thyristor dimming system that meets the EMC standard according to the embodiment of the present invention has at least the following beneficial effects: the driving power supply is electrically connected to the thyristor dimmer through the control line to sample the dimming signal of the thyristor dimmer, the thyristor freewheeling module maintains the conduction state of the thyristor, and then the conduction angle signal of the dimming signal is sampled by the thyristor sampling module, and then the signal isolation processing of the isolation module is sent to the dimming control module to control the output PWM, so that changing the conduction angle of the thyristor is equivalent to changing the brightness of the LED. 1. Since the thyristor dimming part is not connected to the live wire, whether it is 100% load or 10% load, the power module in the driving power supply can input a complete AC signal through the neutral wire and the live wire, and is not affected by the thyristor dimming part. Its harmonics and PF values ​​are well controlled, and can meet the EMC standards of the LED power supply. In any state of the thyristor dimming, the power can be output linearly without being limited by the conduction angle of the thyristor. 2. During dimming, the dimming signal comes from the thyristor freewheeling module and the sampling module, and is not affected by the power of the power module. Regardless of the conduction angle of the thyristor dimmer, the dimming signal is stable, avoiding the difficulty of low-brightness flickering of traditional thyristor dimming. In addition, the dimming response speed is fast, and the dimming can also be linear, because in the entire dimming range, the power module is in normal working condition, only the weight of the load changes. 3. In the application, if the control line is not connected to the thyristor dimmer, the driving power supply is a conventional non-dimming power supply, which does not affect normal use. When dimming is required, the control line is connected to the thyristor dimmer, and the neutral line and live line are normally connected to the power module. The overall wiring is convenient, and one dimmer can be connected to the control lines of multiple power supplies to achieve synchronous dimming.

[0006] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings; Figure 1 This is the principle block diagram of the thyristor dimming system that meets the EMC standard; Figure 2 This is a schematic diagram of synchronous dimming of multiple driving power supplies; Figure 3 This is the circuit schematic of the thyristor dimming system that meets the EMC standard. DETAILED DESCRIPTION

[0008] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0009] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0010] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0011] Reference Figures 1 to 3The present invention provides a thyristor dimming system that meets the EMC standard, including a driving power supply and a thyristor dimmer, wherein the driving power supply includes a power module 10, a control line, a thyristor freewheeling module 11, a thyristor sampling module 12, an isolation module 13 and a dimming control module, wherein the input end of the power module 10 is connected to a live wire and a neutral wire, the thyristor dimmer is electrically connected to one end of the control line, the other end of the control line is electrically connected to the input end of the thyristor freewheeling module 11, the output end of the thyristor freewheeling module 11 is electrically connected to the output end of the thyristor sampling module 12 The input end is electrically connected, the output end of the thyristor sampling module 12 is electrically connected to one end of the isolation module 13, the other end of the isolation module 13 is electrically connected to the input end of the dimming control module, and the output end of the dimming control module is electrically connected to the output end of the power supply module 10 to output a PWM signal to drive the LED load; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module 12 through the thyristor freewheeling module 11, and the thyristor sampling module 12 can convert the dimming signal into a square wave signal to control the dimming control module to output a PWM signal. That is, the driving power supply is electrically connected to the thyristor dimmer through the control line to sample the dimming signal of the thyristor dimmer, the thyristor freewheeling module 11 maintains the thyristor conduction state, and then the thyristor sampling module 12 obtains the conduction angle signal of the dimming signal, and then the signal isolation processing of the isolation module 13 is sent to the dimming control module to control the output PWM, so that changing the conduction angle of the thyristor is equivalent to changing the brightness of the LED. It has the following advantages: 1. Since the thyristor dimming part is not connected to the live wire, whether it is 100% load or 10% load, the power module 10 in the driving power supply can input a complete AC signal through the neutral wire and live wire, and is not affected by the thyristor dimming part. Its harmonics and PF values ​​are well controlled, and can meet the EMC standards of LED power supply. It can output power linearly in any state of thyristor dimming, and is not limited by the thyristor conduction angle. 2. During dimming, the dimming signal comes from the thyristor freewheeling module 11 and the sampling module, and is not affected by the power size of the power module 10. Regardless of the conduction angle of the thyristor dimmer, the dimming signal is stable, avoiding the difficulty of low-brightness flickering of traditional thyristor dimming, and the dimming response speed is fast, and the dimming can also be linear, because in the entire dimming range, the power module 10 is in normal working state, only the weight of the load changes. 3. In application, if the control line is not connected to the thyristor dimmer, the driving power supply is a conventional non-dimming power supply, which does not affect normal use. When dimming is required, the control line is connected to the thyristor dimmer, and the neutral line and the live line are normally connected to the power module 10, and the overall wiring is convenient.

[0012] like Figure 2 In some embodiments, there are multiple driving power supplies, and a thyristor dimmer is electrically connected to the control lines of the multiple driving power supplies to achieve synchronous dimming.

[0013] like Figure 3 In some embodiments, the thyristor freewheeling module 11 includes a diode D1, a constant current IC U2, a resistor R5 and a MOS tube Q2. The anode of the diode D1 is electrically connected to the thyristor dimmer, the cathode of the diode D1 is electrically connected to one end of the constant current IC U2, the other end of the constant current IC U2 is electrically connected to the drain of the MOS tube Q2 via the series voltage-dividing resistor R5, the source of the MOS tube Q2 is grounded, and the gate of the MOS tube Q2 is electrically connected to the thyristor sampling module 12. The thyristor sampling module 12 includes a MOS tube Q3, a resistor R1, and a resistor R3. One end of the resistor R1 is electrically connected to the gate of the MOS tube Q3, the other end of the resistor R1 is electrically connected to the cathode of the diode D1, the source of the MOS tube Q3 is grounded, one end of the resistor R3 is connected to the VCC voltage, and the drain of the MOS tube Q3 is electrically connected to the other end of the resistor R3 and the isolation module 13 respectively. The isolation module 13 uses an optocoupler U3. The dimming control module includes an integration circuit 14 and a main control chip U1. The integration circuit 14 includes a MOS tube Q4, a resistor R2, a resistor R4 and a capacitor C1. One output end of the isolation module is electrically connected to the drain of the MOS tube Q2 and one end of the resistor R2 via the series resistor R4, respectively. The other end of the resistor R2 is electrically connected to one end of the capacitor C1 and the input end of the main control chip U1, respectively. The other end of the capacitor C1 and the source of the MOS tube Q4 are grounded respectively. The other output end of the isolation module 13 is electrically connected to the gate of the MOS tube Q4 via the series resistor. Among them, U2 is a linear constant current IC, and its constant current is slightly larger than the thyristor freewheeling value, generally greater than about 20mA. The current is determined by the constant current IC U2. ZD1 is a voltage regulator to protect the MOS driver. Generally, a 12V voltage regulator is used. Resistor R1 provides a bias voltage for the MOS tube to turn on. When the thyristor dimmer is turned on, MOS tube Q2 is turned on, and MOS tube Q3 is also turned on. At this time, the optocoupler U3 is cut off, and the emitter of the optocoupler U3 outputs a high level through the resistor R9 to control the MOS tube Q4 to turn on, and outputs a low level through the resistor R2. When the thyristor dimmer is not turned on, the VIN node connected to one end of the resistor R1 has no voltage, the MOS tube Q3 is cut off, the optocoupler U3 is turned on, and the emitter of the optocoupler U3 outputs a low level through the resistor R9 to control the MOS tube Q4 to turn off. At this time, the 5V voltage passes through the resistor R4 The resistor R2 charges the capacitor C1 to form an integration circuit 14. By adjusting the parameters, a smooth voltage value can be obtained on the capacitor C1, and the voltage value is controlled by the conduction angle of the thyristor. The main control chip U1 outputs a PWM signal from pin 3 to drive the MOS tube Q1 according to the voltage value on the capacitor C1, thereby realizing the brightness adjustment of the LED.

[0014] That is, the key to the thyristor dimming system is to add another control line, which is specifically used to sample the thyristor dimming signal, and the power module 10 in the driving power supply can be various power supply topologies. Their working principles are the same as those of normal power supplies (generally including a lightning surge module, a rectifier module, a PFC module, a power conversion module, a rectifier and filter module, and a PWM output module, which are used to convert the AC power into a voltage to power the LED). The input power is L / N. If the metal casing also includes a ground wire, the input voltage range can be 100-277V. During the dimming process, the input sinusoidal waveform of the power supply is complete and is not affected by the conduction angle of the thyristor dimmer. Therefore, its PF value / harmonic noise can easily meet the EMC standard range. The control line added to the system is specifically used to sample the thyristor dimming signal. Any conduction angle of the thyristor will not affect the input sinusoidal waveform of the power module 10, and the thyristor freewheeling circuit uses a simple linear constant current to obtain a stable thyristor freewheeling state. The freewheeling circuit can obtain a square wave waveform with the same input sinusoidal frequency according to the conduction angle of the thyristor. The pulse width of the square wave waveform is controlled by the conduction angle of the thyristor. The square wave waveform is then isolated to the secondary of the power module 10 through the optical coupler U3. The dimming control module converts the square wave waveform into a voltage signal through the integration circuit 14, and then converts the voltage signal into a dimming PWM signal to control the output circuit. In this way, changing the conduction angle of the thyristor is equivalent to changing the output LED brightness. Regardless of the conduction angle of the thyristor, the LED dimming can be done stably, avoiding the difficulty of low-brightness flickering of traditional thyristor dimming. Moreover, the dimming response speed is fast and the dimming can be linear, because the power module 10 is in normal working condition in the entire dimming range, it is just the weight of the load, and the existing thyristor dimming is very small when the thyristor conduction angle is very small, which is equivalent to a small effective sine waveform, and the input energy is very small. At this time, the power supply is in under-voltage protection due to the low input voltage or energy or it takes a long time to start, so the dimming response is very slow, generally delayed by 2-3 seconds, which is also impossible to improve with traditional hardware circuits.

[0015] The thyristor freewheeling module 11 can have many forms, but they are all thyristor freewheeling in essence. After the thyristor is turned on, it maintains a controllable conduction effect. The thyristor sampling module 12 is essentially to convert the input waveform into a square wave, which can be obtained in a variety of existing ways. The isolation module 13 uses optocoupler isolation, and can also use a digital isolation chip. The dimming control module also uses the square wave signal as the control signal to output PWM to control the MOS tube Q1 and thus control the brightness change of the output load LED.

[0016] It is easy for those skilled in the art to understand that the above preferred embodiments can be freely combined and superimposed without conflict.

[0017] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A thyristor dimming system that meets EMC standards, characterized in that: include: A driving power supply and a thyristor dimmer, the driving power supply comprising a power module (10), a control line, a thyristor freewheeling module (11), a thyristor sampling module (12), an isolation module (13) and a dimming control module, the input end of the power module (10) being connected to a live wire and a neutral wire, the thyristor dimmer being electrically connected to one end of the control line, the other end of the control line being electrically connected to the input end of the thyristor freewheeling module (11), the output end of the thyristor freewheeling module (11) being electrically connected to the input end of the thyristor sampling module (12), and the thyristor sampling module The output end of the thyristor dimmer (12) is electrically connected to one end of the isolation module (13), the other end of the isolation module (13) is electrically connected to the input end of the dimming control module, and the output end of the dimming control module is electrically connected to the output end of the power module (10) to output a PWM signal to drive the LED load; the dimming signal of the thyristor dimmer is transmitted to the thyristor sampling module (12) via the thyristor freewheeling module (11), and the thyristor sampling module (12) is capable of converting the dimming signal into a square wave signal to control the dimming control module to output a PWM signal.

2. The thyristor dimming system that meets the EMC standard according to claim 1 is characterized in that: The thyristor freewheeling module (11) comprises a diode D1, a constant current IC U2, a resistor R5 and a diode Q2, wherein the anode of the diode D1 is electrically connected to the thyristor dimmer, the cathode of the diode D1 is electrically connected to one end of the constant current IC U2, the other end of the constant current IC U2 is electrically connected to the drain of the MOS tube Q2 via the series voltage divider resistor R5, the source of the MOS tube Q2 is grounded, and the gate of the MOS tube Q2 is electrically connected to the thyristor sampling module (12).

3. The thyristor dimming system meeting the EMC standard according to claim 2, characterized in that: The thyristor sampling module (12) comprises a MOS tube Q3, a resistor R1, and a resistor R3, one end of the resistor R1 is electrically connected to the gate of the MOS tube Q3, the other end of the resistor R1 is electrically connected to the cathode of the diode D1, the source of the MOS tube Q3 is grounded, one end of the resistor R3 is connected to a VCC voltage, and the drain of the MOS tube Q3 is electrically connected to the other end of the resistor R3 and the isolation module (13) respectively.

4. The thyristor dimming system meeting the EMC standard according to claim 1, characterized in that: The isolation module (13) uses an optical coupler U3.

5. The thyristor dimming system meeting the EMC standard according to claim 1, characterized in that: The dimming control module comprises an integration circuit (14) and a main control chip U1; the input end of the integration circuit (14) is electrically connected to the isolation module (13); the integration circuit (14) can be charged when the thyristor dimmer is not turned on to output a smooth voltage value; the output end of the integration circuit (14) is electrically connected to the input end of the main control chip U1; the main control chip U1 outputs a corresponding PWM signal according to the voltage value.

6. The thyristor dimming system meeting the EMC standard according to claim 5, characterized in that: The integration circuit (14) comprises a MOS tube Q4, a resistor R2, a resistor R4 and a capacitor C1; an output end of the isolation module (13) is electrically connected to the drain of the MOS tube Q2 and one end of the resistor R2 via the series resistor R4; the other end of the resistor R2 is electrically connected to one end of the capacitor C1 and the input end of the main control chip U1; the other end of the capacitor C1 and the source of the MOS tube Q4 are grounded; the other output end of the isolation module (13) is electrically connected to the gate of the MOS tube Q4 via the series resistor.

7. The thyristor dimming system meeting the EMC standard according to claim 1, characterized in that: There are multiple driving power supplies, and the thyristor dimmer is electrically connected to the control lines of the multiple driving power supplies respectively to achieve synchronous dimming.

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