A control system for improving phase-cut dimming performance

Abstract

The present invention relates to a control system for improving phase-cut dimming performance, the control system comprising a power grid input and dimmer module (1), a PFC module (2) connected to the power grid input and dimmer module (1), and an output constant voltage and dimming module (3) connected to the PFC module (2), the control system also comprising a control module (4) respectively connected to the power grid input and dimmer module (1) and the PFC module (2) and utilizing the boost characteristics of the PFC and the output electrolytic characteristics of the PFC in combination with the dimming mode of the power grid input and dimmer module (1) to use the phase-cut duty cycle of the dimming power supply as a dimming input signal of the output constant voltage and dimming module (3) to control the start time point of the PFC module (2); the control module (4) is also electrically connected to the output constant voltage and dimming module (3) to control the dimming of the output constant voltage and dimming module (3). The circuit can improve the phase-cut dimming performance.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a control system for improving phase-cut dimming performance. Background Art

[0002] In the existing constant voltage phase-cut dimming system, there are many brands of dimmers, and the specifications of dimmers produced by different manufacturers are different. There is no special and universal driving system in the existing circuit. In actual use, ordinary constant voltage drive is used. The phase-cut dimmer is divided into front phase-cut and rear phase-cut. In order to realize the phase-cut dimming function, the power supply of the ordinary constant voltage drive must be adjusted according to the phase-cut type and specifications of the dimmer to meet the normal working requirements of the dimmer, which makes the circuit system design complicated.

[0003] More importantly, in the front-cut dimmer circuit system, the dimming power supply needs to provide a maintenance current during the conduction period of the thyristor so that the thyristor can conduct normally, and a very small impedance during the off period for the start of the next phase-cut cycle; in the rear-cut dimming system, the differential mode voltage in the circuit system needs to be discharged cleanly after the MOS tube inside the dimmer is turned off, so that the dimmer can start normally in the next cycle.

[0004] At present, most of the solutions on the market are to add a discharge circuit to the hardware to solve the voltage discharge problem of the latter phase, and to set an RC filter at the input end of the detection power supply and adjust the RC time constant to a very large value to filter out the jitter problem caused by the inability to maintain a stable current due to the large change of the former phase signal, or to add a maintenance current detector to the main circuit to add an additional current when the current is insufficient.

[0005] However, a very large RC filter constant will result in a very slow dimming response speed. When the constant voltage drive circuit is working, it is necessary to first complete the phase-cut signal detection, and then use the phase-cut signal to control the duty cycle of the PWM MOS tube in the constant voltage output circuit. The existing phase-cut signals are mostly the average value after RC filtering, which makes the detected phase-cut signal lag, resulting in the dimming input signal not being the real power signal of the front end, resulting in poor dimming performance.

[0006] At the same time, the design incompatibility of ordinary constant voltage drive in specific circuits makes the rear-cut phase circuit fail to make corresponding control for the maintenance current characteristics of the front-cut phase, causing the dimmer to work in an abnormal state in most intervals and not applicable to the front-cut phase; the front-cut phase circuit is not applicable to the rear-cut phase dimmer, resulting in the rear-cut dimmer having basically no dimming effect when the power load is low; although adding a current maintainer to the main circuit can improve the front-cut dimming effect, it increases additional losses. Summary of the invention

[0007] In view of the above problems, an object of the present invention is to provide a control system which can skillfully use the phase-cutting duty cycle as a dimming input signal by controlling the start and stop time points of the PFC to obtain a better dimming performance effect.

[0008] In order to achieve the above object, the technical solution of the present invention is: a control system for improving phase-cut dimming performance, the control system includes a power grid input and dimmer module, a PFC module connected to the power grid input and dimmer module, and an output constant voltage and dimming module connected to the PFC module, characterized in that:

[0009] The control system also includes a control module which is respectively connected to the grid input and dimmer module and the PFC module, and utilizes the boost characteristics of the PFC and the output electrolytic characteristics of the PFC in combination with the grid input and the dimming mode of the dimmer module to use the phase-cutting duty cycle of the phase-cutting dimmer as the dimming input signal of the output constant voltage and dimming module to control the start-up time point of the PFC module. The control module is also electrically connected to the output constant voltage and dimming module to control the dimming of the output constant voltage and dimming module.

[0010] Furthermore, the control module includes a control chip electrically connected to the grid input and the dimmer module to obtain power supply information and judge the dimming mode of the grid input and the dimmer module accordingly, and a drive enable module respectively connected to the control chip and the PFC module and driving the PFC module to turn on at a start-up time point in the corresponding dimming mode under the control of the control chip.

[0011] Furthermore, the dimming modes include a leading phase dimming mode, a trailing phase dimming mode and a dimmer-unconnected mode;

[0012] The start-up time points include a first time point when the control chip in the front-phase dimming mode controls the drive enable module to drive the PFC module to turn on when the output voltage of the phase dimmer drops to a threshold value so as to use the output electrolytic capacitor of the PFC module to provide a maintenance current, a second time point when the control chip in the rear-phase dimming mode controls the drive enable module at a related breakpoint to drive the PFC module to turn on so as to use the output electrolytic capacitor of the PFC module for discharge, and a third time point when the control chip determines that the dimmer is not connected, controls the drive enable module to enable so that the PFC module can operate freely according to its own characteristics.

[0013] Furthermore, the control system also includes an input voltage detection module connected between the grid input and dimmer module and the control chip to obtain power information and transmit the power information to the control chip.

[0014] Furthermore, the power supply information includes a voltage amplitude signal and a voltage slope signal.

[0015] Further, the PFC module includes a PFC chip, a first switch component electrically connected to the PFC chip and the output constant voltage and dimming module;

[0016] The driving enabling module includes a second switch component arranged between the PFC chip and the first switch component to control whether the PFC chip is connected to the first switch component. The second switch component is also connected to the control chip and is controlled by the control chip to be turned on or off.

[0017] Further, the second switch component includes a first NPN transistor and a first PNP transistor, the base of the first NPN transistor is connected to the control chip, the emitter is grounded, and the collector is connected to the base of the first PNP transistor;

[0018] The emitter of the first PNP transistor is connected to the PFC chip and the collector is connected to the first switch component.

[0019] Furthermore, the first switch component is an N-channel MOS tube, and the output of the PFC module is electrolytically connected between the N-channel MOS tube and the output constant voltage and dimming module.

[0020] Furthermore, the input voltage detection module includes a rectifier component connected to the grid input and the dimmer module, and a voltage-dividing resistor component connected between the rectifier component and the control chip to obtain voltage and transmit the voltage to the control chip.

[0021] Furthermore, the threshold is 1 / 2 of the maximum value of the grid input and the output voltage of the dimmer module.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] The dimming mode is determined by collecting voltage amplitude signals and voltage slope change signals, and the PFC module is controlled according to the dimming mode to be in a closed state in the early stage of the pre-phase-cutting mode and to be turned on when the output voltage of the phase-cutting dimmer drops to the threshold value, and the output electrolysis of the PFC is used for continuous current. In the post-phase-cutting mode, the PFC module is turned on at the relevant breakpoint, and the output electrolysis of the PFC is used for discharge. When the dimmer is not connected, the PFC operates according to its own characteristics, which well realizes the compatibility of the dimming circuit with different dimming modes, and according to the circuit characteristics of different dimming modes, the output electrolysis of the PFC is cleverly used to solve the problems of unstable continuous current or poor discharge effect, and the phase-cutting waveform is well restored, so that the phase-cutting duty cycle is directly used as the input signal for dimming, which makes the output stable and improves the dimming performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an overall structural block diagram for improving the phase-cut dimming performance of this application.

[0025] Figure 2 A circuit schematic diagram for improving phase-cut dimming performance in this application. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0027] Figure 1-2 The preferred embodiment of the present application for improving phase-cut dimming performance is shown. As shown in the figure, the control system includes a grid input and dimmer module 1, a PFC module 2 connected to the grid input and dimmer module 1, and an output constant voltage and dimming module 3 connected to the PFC module 2.

[0028] As described in the background technology, the front-cut phase circuit has the problem of insufficient maintenance current and restart due to oscillation when the thyristor of the dimmer is turned on for the first time, and the rear-cut phase circuit has the problem of poor discharge and cannot start normally in the next cycle. RC filtering can solve the oscillation jitter problem, but it will cause the acquired phase-cut signal to lag, so that the dimming circuit cannot follow the dimming power supply at the front end to perform dimming operations, resulting in poor dimming performance. Adding hardware devices can solve the problem of poor discharge, but it increases circuit losses.

[0029] At the same time, the existing constant voltage driving circuit is not compatible with different dimming modes. In other words, if the existing constant voltage driving circuit is used for trailing phase dimming, it cannot be used for leading phase dimming, and vice versa. The circuit's non-universality leads to increased design costs.

[0030] In order to solve this problem, the present application sets up a control module 4 in the circuit, which is connected to the grid input and the dimmer module 1 and the PFC module 2 respectively, and can utilize the boost characteristics of the PFC and the output electrolytic characteristics of the PFC in combination with the grid input and the dimming mode of the dimmer module 1 to use the phase-cutting duty cycle of the phase-cutting dimmer as the output constant voltage and the dimming input signal of the dimming module 3, thereby controlling the start-up time point of the PFC module 2, making the dimming input signal closer to the front-end dimming power supply, and improving the dimming performance.

[0031] The PFC module 2 provides driving power for the output constant voltage and dimming module 3 at the back end, and the specific dimming operation needs to be controlled by the control module 4, so the control module 4 is also electrically connected to the output constant voltage and dimming module 3 to control the dimming of the output constant voltage and dimming module 3. Since the specific electrical connection design is not the focus of protection of this application, different manufacturers can choose the specific connection control method according to their actual needs, and it belongs to a conventional design, so it will not be elaborated here.

[0032] In the present application, the control module 4 includes a control chip 41 electrically connected to the grid input and the dimmer module 1 to obtain power supply information and judge the dimming mode of the grid input and the dimmer module 1 accordingly, and a drive enable module 42 respectively connected to the control chip 41 and the PFC module 2 and driving the PFC module 2 to turn on at the start-up time point in the corresponding dimming mode under the control of the control chip 41.

[0033] The dimming mode includes a front-phase dimming mode, a rear-phase dimming mode and a dimmer-not-connected mode, and the start-up time points correspond to a first time point in which the control chip 41 controls the drive enable module 42 to drive the PFC module 2 to turn on when the output voltage of the phase dimmer drops to a threshold value to use the output electrolyte of the PFC module 2 to provide a maintaining current in the front-phase dimming mode, a second time point in which the control chip 41 controls the drive enable module 42 to drive the PFC module 2 to turn on at a related breakpoint to use the output electrolyte of the PFC module 2 for discharge, and a third time point in which the control chip 41 controls the drive enable module 42 to enable the PFC module 4 to operate freely according to its own characteristics when it determines that the dimmer is not connected.

[0034] PFC has a boost function during operation, and its output electrolytic capacitor will continue to be in a boost state when PFC is in operation, and its potential difference is higher than the maximum voltage value of the front-end grid input and the output of the dimmer module 1. PFC operates according to its own characteristics in the previous dimming circuit, resulting in PFC being continuously in operation during a cycle of the thyristor conduction, and the output electrolytic capacitor of PFC being continuously in a high-voltage state, especially for the front-cut phase dimming mode, the voltage and current suddenly change at the moment when the thyristor is turned on for the first time, making the current in the circuit greater than the current required for the thyristor to conduct, and the thyristor is briefly turned on, but as the voltage and current fall back and stabilize, the current in the dimming circuit gradually decreases to below the current value required for the thyristor to conduct. The continuous operation of PFC and the boost characteristics make the output electrolytic capacitor unable to provide the circuit with supply current, resulting in current oscillation after the thyristor is briefly turned on, and the maintenance current is insufficient and forced to shut down and restart. The thyristor of the dimmer is constantly turned on-off-restarted, which will cause the output voltage to be unstable and seriously affect the dimming effect.

[0035] In the present application, a control module is added to control the start-up time of the PFC module according to the dimming mode. Before the thyristor is turned on for the first time, the PFC is in the off state. When the circuit current drops, that is, when the output voltage drops to the threshold value, the PFC is turned on. The boost function of the PFC is used to raise the voltage of the output electrolytic capacitor so that the circuit current can be maintained, and the current that is about to drop is replenished to maintain it above the maintenance current. The characteristic that the output electrolytic capacitor will continue to be in the boost state afterwards is used to ensure that the current in the circuit continues to remain stable, and the thyristor is continuously turned on, thereby ensuring the output voltage is stable, solving the problem of continuously providing the maintenance current in the front-cut mode. In the rear-cut mode, turning on the PFC at the relevant breakpoint can transfer and release the energy in the circuit to the output electrolytic capacitor of the PFC to complete the discharge. When the output voltage signal of the dimming power supply drops to the set value, the PFC is turned off. In this way, the discharge can be ensured to be clean.

[0036] In the present application, whether the PFC is turned on or off in the front-cut mode or the PFC is turned on or off in the rear-cut mode, the duty cycle of the phase-cut signal is fully utilized, and the PFC is turned on or off according to the duty cycle, so that the back-end circuit follows the voltage waveform changes of the front-end grid input and the dimmer module very well. In other words, the back-end dimming circuit uses the duty cycle of the phase-cut signal as the dimming input signal, and realizes the dimming function of the back-end output constant voltage and dimming module, which is accurate and effective. In this embodiment, the threshold is selected as 1 / 2 of the maximum voltage of the grid input and the output of the dimmer module. Of course, it can also be other values, which are specifically determined by the thyristor and the entire circuit design.

[0037] In order to obtain the power supply information of the front-end grid input and the dimmer module 1, the control system also includes an input voltage detection module 5 connected between the grid input and the dimmer module 1 and the control chip 41 to obtain the power supply information and transmit the power supply information to the control chip 41. The power supply information includes a voltage amplitude signal and a voltage slope signal. For the front-cut phase dimming mode, the voltage slope changes significantly, while the voltage slope changes more slowly in the rear-cut mode. Therefore, according to the voltage amplitude and the slope change, it can be well distinguished whether it is front-cut or rear-cut or whether the dimmer is not connected. It is specifically realized by software algorithm and will not be elaborated in detail here.

[0038] like Figure 2 As shown, the PFC module 2 includes a PFC chip 21, a first switch component 22 electrically connected to the PFC chip 21 and the output constant voltage and dimming module 3, and the drive enabling module 42 includes a second switch component arranged between the PFC chip 41 and the first switch component 22 to control whether the PFC chip 21 is connected to the first switch component 22, and the second switch component is also connected to the control chip 41 and is controlled by the control chip 41 to be turned on or off.

[0039] Specifically, the second switch component includes a first NPN transistor Q11 and a first PNP transistor Q12, the base of the first NPN transistor Q11 is connected to the control chip 41, the emitter is grounded, and the collector is connected to the base of the first PNP transistor Q12, the emitter of the first PNP transistor Q12 is connected to the PFC chip 21, and the collector is connected to the first switch component, the first switch component 22 is an N-channel MOS transistor Q1, and the output electrolyte C31 of the PFC module 2 is connected between the N-channel MOS transistor Q1 and the output constant voltage and dimming module 3. Of course, the second switch component can also be other turn-off devices, such as a combination of MOS transistors and MOS transistors, or MOS transistors and transistors, as long as it can be realized by its own conduction or shutdown to determine whether the PFC chip and the first switch component are turned on or off.

[0040] The input voltage detection module 5 includes a rectifier component 51 connected to the grid input and the dimmer module 1, and a voltage-dividing resistor component 52 connected between the rectifier component 51 and the control chip 41 to obtain the voltage and transmit the voltage to the control chip 41. Figure 2 As shown, the voltage-dividing resistor component 52 includes resistors R62, R63, R64, and R65 connected in series, wherein a capacitor C36 is connected in parallel at both ends of R65 to form an RC filter. The voltage-dividing resistor component 52 transmits the acquired voltage difference signal on the voltage-dividing resistor R65 to the control chip 41. The control chip 41 calculates the voltage change according to the program code burned inside itself and the collected multiple voltage values, thereby determining the dimming mode, which is not repeated here.

[0041] The present application determines the dimming mode by collecting voltage amplitude signals and voltage slope change signals, and controls the PFC module to be in an off state in the early stage of the front-phase mode according to the dimming mode and to be turned on when the dimming power supply voltage drops to the threshold value, and uses the output electrolysis of the PFC to continue the current, and turns on the PFC module at the relevant breakpoint in the post-phase mode, and uses the output electrolysis of the PFC to discharge, and makes the PFC operate according to its own characteristics when the dimmer is not connected. According to the circuit characteristics of the dimming mode itself, the output electrolysis of the PFC is cleverly used to solve the problems of unstable follow-up or poor discharge effect, and the phase-cut waveform is well restored, so that the phase-cut duty cycle is directly used as the input signal for dimming, thereby improving the dimming performance.

[0042] Although embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A control system for improving phase-cut dimming performance, the control system comprising a power grid input and dimmer module (1), a PFC module (2) connected to the power grid input and dimmer module (1), and an output constant voltage and dimming module (3) connected to the PFC module (2), characterized in that: The control system further comprises a control module (4) which is connected to the grid input and dimmer module (1) and the PFC module (2) respectively and which utilizes the boost characteristics of the PFC and the output electrolytic characteristics of the PFC in combination with the grid input and the dimming mode of the dimmer module (1) to use the phase-cutting duty cycle of the phase-cutting dimmer as the output constant voltage and dimming input signal of the dimming module (3) to control the start-up time point of the PFC module (2); The dimming modes include a leading phase dimming mode, a trailing phase dimming mode and a dimmer-not-connected mode; The start-up time point comprises a first time point in which the control chip (41) controls the drive enable module (42) to drive the PFC module (2) to start up in the front-cut phase dimming mode when the output voltage of the phase dimmer drops to a threshold value so as to use the output electrolyte (C31) of the PFC module (4) to provide a maintenance current; a second time point in which the control chip (41) controls the drive enable module (42) to drive the PFC module (2) to start up at a relevant breakpoint in the rear-cut phase dimming mode so as to use the output electrolyte (C31) of the PFC module (2) for discharge; and a third time point in which the control chip (41) controls the drive enable module (42) to enable when it determines that the dimmer is not connected so as to allow the PFC module (2) to run freely according to its own characteristics; the control module (4) obtains power supply information and determines the dimming mode of the dimmer module (1) accordingly; the power supply information comprises a voltage amplitude signal and a voltage slope signal; The control module (4) is also electrically connected to the output constant voltage and dimming module (3) to control the dimming of the output constant voltage and dimming module (3).

2. The control system for improving phase-cut dimming performance according to claim 1, characterized in that: The control module (4) comprises a control chip (41) electrically connected to the power grid input and the dimmer module (1) to obtain power supply information and judge the dimming mode of the power grid input and the dimmer module (1) based on the power supply information, and a drive enable module (42) connected to the control chip (41) and the PFC module (2) respectively and driving the PFC module (2) to turn on at a start time point corresponding to the dimming mode under the control of the control chip (41).

3. The control system for improving phase-cut dimming performance according to claim 2, characterized in that: The control system further comprises an input voltage detection module (5) connected between the grid input and dimmer module (1) and the control chip (41) to obtain power supply information and transmit the power supply information to the control chip (41).

4. The control system for improving phase-cut dimming performance according to claim 2, characterized in that: The PFC module (2) comprises a PFC chip (21), and a first switch component (22) electrically connected to the PFC chip (21) and the output constant voltage and dimming module (3); The drive enabling module (42) comprises a second switch component arranged between the PFC chip (21) and the first switch component (22) to control whether the PFC chip (21) is connected to the first switch component (22); the second switch component is also connected to the control chip (41) and is controlled by the control chip (41) to be turned on or off.

5. The control system for improving phase-cut dimming performance according to claim 4, characterized in that: The second switch component comprises a first NPN transistor (Q11) and a first PNP transistor (Q12), wherein the base of the first NPN transistor (Q11) is connected to the control chip (41), the emitter is grounded, and the collector is connected to the base of the first PNP transistor (Q12); The emitter of the first PNP transistor (Q12) is connected to the PFC chip (21) and the collector is connected to the first switch component (22).

6. The control system for improving phase-cut dimming performance according to claim 4, characterized in that: The first switch component (22) is an N-channel MOS tube (Q1), and the output electrolyte (C31) of the PFC module (4) is connected between the N-channel MOS tube (Q1) and the output constant voltage and dimming module (3).

7. The control system for improving phase-cut dimming performance according to claim 3, characterized in that: The input voltage detection module (5) comprises a rectifier component (51) connected to the grid input and the dimmer module (1), and a voltage-dividing resistor component (52) connected between the rectifier component (51) and the control chip (41) to obtain a voltage signal and transmit the voltage signal to the control chip (41).

8. The control system for improving phase-cut dimming performance according to claim 1, characterized in that: The threshold is 1 / 2 of the maximum value of the grid input and the output voltage of the dimmer module (1).

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