[0033] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary, and are only used to explain the present invention, but should not be understood as limiting the present invention.
[0034] In the description of the present invention, several means one or more, multiple means two or more, greater than, less than, exceeding, etc. are understood to not include the number, and above, below, and within are understood to include the number. If it is described that the first and second are only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying the relative importance or implicitly specifying the number of the indicated technical features or implicitly specifying the order of the indicated technical features relationship.
[0035] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installation, and connection should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the above terms in the present invention in combination with the specific content of the technical solution.
[0036] Reference figure 1 with figure 2 The phase dimming circuit according to the embodiment of the first aspect of the present invention includes a dimmer 100, a phase discriminating circuit 200, and a driving circuit 300. The dimmer 100 is any embodiment of the high-power MOSFT dimming circuit disclosed in the invention patent with publication number CN 108337774A. By modifying the configuration of the main control chip, the dimmer 100 can output in phases φ and A narrow pulse AC sine wave is set at the phase φ+π, the waveform of the sine wave is referenced Image 6 As shown in the waveform A, the narrow pulse at the phase φ is a negative pulse, and the narrow pulse at the phase φ+π is a positive pulse. The duration t of the narrow pulse satisfies 50≤t≤100. The output of the dimmer 100 is connected to the input of the phase discriminating circuit 200. The sine wave is sent to the phase discriminating circuit 200. The phase discriminating circuit 200 performs a series of transformations on the sine wave, and obtains the phase φ at the beginning of the narrow pulse from it, According to φ, a PWM square wave with a certain duty ratio or a DC control level of a certain value is generated. The output terminal of the phase discrimination circuit 200 is connected to the input terminal of the driving circuit 300, and the output terminal of the driving circuit 300 is connected to the light source power supply. The driving circuit 300 controls the output of the light source power supply according to the input PWM square wave or DC control level, thereby controlling the light source The brightness changes. Since the modulating sine wave only has a narrow pulse with a short duration to mark the phase φ, the modulating waveform is similar to a complete sine wave, and there will be no periodic current sudden changes, which will not cause damage to the power grid. Influence, can also extend the life of power devices.
[0037] In a further embodiment, the phase detection circuit 200 includes a single chip microcomputer 210, a rectifier circuit 220, a zero-crossing identification circuit 230, and a phase identification circuit 240. The single chip microcomputer 210 is mainly used to calculate the phase φ according to the input waveform, and output a PWM square wave corresponding to the duty cycle D according to the phase φ. The input terminal of the rectifier circuit 220 is used as the input terminal of the phase discrimination circuit 200 and is connected to the output terminal of the dimmer 100 to rectify the input sine wave with narrow pulse blocking to facilitate subsequent parameter measurement and calculation. It can be understood that the rectifier circuit 220 may use rectifier elements such as vacuum diodes, gas tubes, semiconductor diodes, or silicon controlled rectifiers.
[0038] The input terminal of the zero-crossing identification circuit 230 is connected to the output terminal of the rectifying circuit 220, and is used to block and filter out the narrow pulses in the rectified sine wave, so as to identify the zero-crossing point of the sine wave. By measuring the zero-crossing identification circuit 230 The period T can be obtained by the time interval between two adjacent points closest to 0. The output terminal of the zero-crossing identification circuit 230 is connected to the single-chip 210. It can be understood that the zero-crossing identification circuit 230 may adopt RC filtering or an amplitude filtering method. The input terminal of the phase identification circuit 240 is connected to the output terminal of the rectifier circuit 220, and is used to reverse the blocking part of the narrow pulse in the rectified sine wave, that is, to detect the narrow pulse and output a low level with the same duration as the narrow pulse. In order to measure the start time of the narrow pulse, the output terminal of the phase identification circuit 240 is connected to the single chip microcomputer 210.
[0039] Reference Image 6 Waveform C, Waveform D, and Waveform E, wherein Waveform C is the output waveform of the zero-crossing recognition circuit 230, Waveform D is the output waveform of the phase recognition circuit 240, and Waveform E is the PWM square wave output by the single chip microcomputer 210. The single chip microcomputer 210 respectively detects the time t1 and t2 when the waveform C and the waveform D reach the lowest level in the same period. Since the time t1 when the waveform C reaches the lowest level corresponds to the zero-crossing time of the sine wave, the time t2 when the waveform D reaches the lowest level is the start time of the narrow pulse blocking, so the beginning of the narrow pulse can be obtained by subtracting the two Relative to the interval time of the nearest zero-crossing point ΔT=t2-t1, combined with the period T obtained above, the phase φ=π(ΔT/T) at the narrow pulse can be obtained. The MCU 210 outputs a PWM square wave corresponding to the duty cycle according to the calculated phase φ, such as Image 6 The waveform E is shown in.
[0040] In some embodiments, the phase detection circuit 200 may further include a filter circuit 250. The input end of the filter circuit 250 is connected with the single-chip 210, and is used for filtering the PWM square wave output by the single-chip 210. It can be understood that the filter circuit 250 can only remove the noise in the PWM square wave, or can filter out the low voltage in the PWM square wave, and convert the PWM square wave into a DC control level. The output terminal of the filter circuit 250 is connected to the input terminal of the driving circuit 300.
[0041] Reference below figure 2 , image 3 with Figure 4 The phase dimming circuit according to the embodiment of the present invention is described in detail with a specific embodiment. It should be understood that the following description is only an exemplary description, rather than a specific limitation to the invention.
[0042] Reference figure 1 Shown is a specific embodiment of the dimmer 100 according to the embodiment of the present invention. Because the dimmer 100 in this embodiment adopts the first high-power MOSFT dimming circuit disclosed in the invention patent with publication number CN 108337774 A For the specific circuit structure of this embodiment, please refer to the patent document, which will not be described in detail here. In this embodiment, the duration t of the narrow pulse is 75 microseconds.
[0043] Reference figure 2 , Are specific embodiments of the phase detection circuit 200 and the driving circuit 300 according to the embodiment of the present invention. Reference image 3 , Is a specific embodiment of the rectifier circuit of the present invention. The rectifier circuit 220 includes a connector CON1, a fuse F1, a varistor ZR1, a safety capacitor X1, a negative temperature coefficient thermistor RT1 and a rectifier bridge DB1. One pin of the connector CON1 is connected to node L through the fuse F1 and one end of the varistor ZR1, the other pin of the connector CON1 and the other end of the varistor ZR1 are connected to node N, and the safety capacitor X1 is connected in parallel to the varistor At both ends of ZR1, node L is connected to one end of the input end of the rectifier bridge DB1, node N is connected to the other end of the input end of the rectifier bridge DB1 through a negative temperature coefficient thermistor RT1, CON1 is used as the input end of the rectifier circuit 220, and the output end of the rectifier bridge DB1 The positive pole is the output terminal of the rectifier circuit 220. DB1 uses DB107 integrated rectifier bridge, safety capacitor X1 is used for differential mode and common mode filtering, fuse F1 is used to protect the main components, negative temperature coefficient thermistor RT1 is used for temperature correction, and varistor ZR1 is used For overvoltage protection.
[0044] The zero-crossing identification circuit 230 is an RC filter circuit composed of a resistor R18, a resistor R15, a resistor R20, and a capacitor C15. One end of the resistor R18 is connected to the output terminal of the rectifier circuit 220, the other end of the resistor R18 is grounded through the resistor R15, the resistor R18 and the resistor R15 are connected to the node C, the capacitor C15 is connected in parallel to the two ends of the resistor R15, and the node C is connected to the single-chip microcomputer through the resistor R19 The 7-pin connection of 210, where R19 is used for current limiting.
[0045] The phase identification circuit 240 is composed of a capacitor C6, a capacitor C7, a resistor R21, a resistor R20 and a Zener diode D10. The output ends of the rectifier circuit 220 are respectively connected to one end of the capacitor C6 and the resistor R21, the other end of the capacitor C6 and the other end of the resistor R21 are connected to the node D, the node D is connected to the cathode of the Zener diode D10, and the anode of the Zener diode D10 is grounded. The capacitor C7 is connected in parallel to both ends of the Zener diode D10, and the node D is connected to the 8 pins of the single-chip microcomputer 210 through the resistor R20, where R20 is used for current limiting.
[0046] The filter circuit 250 is composed of a resistor R17, a resistor R16 and a resistor R14. One end of the resistor R17 is connected to the microcontroller 210, the other end of the resistor R17 is respectively connected to one end of the resistor R16 and one end of the resistor R14, the other end of the resistor R16 is connected to the driving circuit 300 as the output dim_det signal of the filter circuit, and the other end of the resistor R14 is grounded. At this time, the filter circuit 250 removes the noise in the PWM square wave output by the single-chip 210. Reference Figure 4 When the capacitor C12 is connected in parallel at both ends of the resistor R14, the filter circuit 250 transforms the output of the single chip microcomputer 210 into a DC control level whose voltage value is proportional to the PWM square wave duty cycle.
[0047] Reference figure 2 , Is a specific embodiment of the drive circuit 300, which includes a power conversion circuit composed of a single-chip microcomputer U1 and a number of protection circuits and switching power devices. The driving circuit 300 is a general light source power source driving circuit, which can drive the light source power source to output a corresponding output voltage according to the input PWM square wave duty cycle or level signal, which is a prior art known or known to those skilled in the art. Therefore, I will not go into details here.
[0048] In the phase dimming circuit of the above embodiment, refer to Figure 5 , Figure 5 I1 is the current waveform of the safety capacitor X1, Figure 5 VF in the dimming power supply driving circuit is the voltage waveform at both ends of the capacitor C8, and the waveforms of I1 and VF have no large fluctuations.
[0049] The phase dimming method according to the second aspect of the present invention can be implemented by the phase dimming circuit of the first aspect of the present invention. The specific steps include the following steps:
[0050] Firstly, the phase φ and the phase φ+π are respectively provided with narrow pulses, and the duration t of the narrow pulses satisfies the sine wave A with 50≤t≤100 microseconds. In some embodiments, the narrow pulse at phase φ is a negative pulse, and the narrow pulse at phase φ+π is a positive pulse.
[0051] Then rectify sine wave A into waveform B.
[0052] Then filter the narrow pulses in the waveform B to obtain the waveform C, and obtain the period T according to the waveform C.
[0053] Obtain waveform C and detect the narrow pulse in waveform B at the same time, and output a low level with the duration of the narrow pulse to mark the narrow pulse to obtain waveform D, and obtain the sine wave at the beginning of the narrow pulse according to waveform C and waveform D A: The interval time of the last zero crossing △T.
[0054] Finally, according to the phase Φ=π(△T/T), the PWM square wave corresponding to the duty cycle is output to the light source power supply.
[0055] Among them, sine wave A, waveform B, waveform C and waveform D can be referred to Image 6 Shown. In combination with the phase dimming circuit of the first aspect of the present invention, the sine wave A with narrow pulse blocking is generated by the dimmer 100, and the remaining steps are completed by the phase discriminating circuit 200. Among them, the rectification of the sine wave A into the waveform B is implemented by the rectification circuit 220; the waveform B is filtered out of narrow pulses to obtain the waveform C implemented by the zero-crossing identification circuit 230; the narrow pulses in the waveform B are detected and output low-level marks to form a waveform D is implemented by the phase identification circuit 240; the period T is obtained through the waveform C and the waveform D, and the measurement and calculation of the interval time ΔT from the beginning of the narrow pulse to the nearest zero crossing is implemented by the single chip microcomputer 210. The specific method for obtaining the period T and the time ΔT has been described in the discussion of the first aspect of the present invention, and will not be repeated here.
[0056] In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples", "specific examples", or "some examples" etc. mean to incorporate the implementation The specific features, structures, materials or characteristics described by the examples or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner.
[0057] According to the phase dimming circuit of the present invention, since a sine wave with narrow pulse blocking is used to transmit phase information, it has a relatively complete sine wave compared to the method of directly chopping the sine wave in the front and back tangential directions. , Will not produce periodic current sudden changes, and will not have an excessive impact on the grid current. At the same time, since there is no large peak current, the power devices in the dimming circuit can be protected.
[0058] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above-mentioned embodiments. Within the scope of knowledge possessed by those of ordinary skill in the technical field, various modifications can be made without departing from the purpose of the present invention. Kind of change.
