CN109688661B

CN109688661B - Single-pulse silicon controlled rectifier back phase-cut dimming method and dimmer

Info

Publication number: CN109688661B
Application number: CN201811600341.7A
Authority: CN
Inventors: 车浩; 黄义深; 刘权爱; 卢嫦嫦
Original assignee: Zhuhai Zhengcheng Electronic Technology Co ltd
Current assignee: Zhuhai Zhengcheng Electronic Technology Co.,Ltd.
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2021-02-19
Anticipated expiration: 2038-12-26
Also published as: CN109688661A

Abstract

The invention provides a single-pulse silicon controlled rectifier back phase-cut dimming method and a dimmer, wherein the method comprises the following steps: the control unit receives a zero-crossing pulse signal of the alternating sine wave generated by the zero-crossing detection unit, generates an external trigger event when the edge jump of the zero-crossing pulse signal is detected, starts an internal counter according to the external trigger event, and outputs a high level to the driving unit when the count of the counter reaches a preset comparison value to control the driving unit to be started; the counter continues counting, when the count of the counter reaches an automatic loading value, a low level is output to the driving unit, the driving unit is controlled to be closed, the count of the counter is cleared and stopped, and a next external trigger event is waited; the automatic loading value is a reference value corresponding to the dimming signal value. The invention adopts a single pulse dimming mode with fixed duty ratio and variable frequency, and the dimming mode is more stable.

Description

Single-pulse silicon controlled rectifier back phase-cut dimming method and dimmer

Technical Field

The invention relates to the technical field of dimmers, in particular to a single-pulse silicon controlled rectifier back-phase-cut dimming method and a dimmer.

Background

The silicon controlled rectifier dimmer is divided into a front-cut type and a rear-cut type, and because the front-cut silicon controlled rectifier dimmer conducts front phase cutting on an alternating current sine wave, voltage and current after zero crossing are suddenly loaded on a capacitive or inductive LED lamp power supply driving load in the dimming process, so that the phenomena of unstable output, flickering of an LED lamp and the like are caused. Such a front-cut thyristor dimmer is not suitable for dimming LED lamps. The silicon controlled rectifier is switched back to phase, and only the waveform after zero crossing is switched back to phase, so that the voltage and current applied to the LED power supply driving load rise steadily, and the silicon controlled rectifier is very suitable for capacitive or inductive LED lamp dimming. In order to achieve the purpose of back cut dimming, a single chip microcomputer is usually used for detecting the zero crossing point of an alternating current sine wave, and a PWM dimming signal is output through software or hardware to control an output field effect transistor within a half period of the sine wave so as to perform back cut dimming on an alternating current waveform.

The software PWM dimming method of the back cut dimmer has many disadvantages, such as inaccurate PWM modulation pulse width, and susceptibility to the influence of software operation size on the PWM frequency and duty ratio, resulting in an uneven and undesirable dimming process. Compared with a software PWM dimming mode, the hardware PWM dimming mode of the post-cut dimmer has obvious advantages. The hardware PWM dimming mode is that the hardware in the singlechip is used for outputting PWM signals, as long as the frequency and the duty ratio are given, a 16-bit counter of the hardware PWM automatically counts, and the counting is controlled without depending on the software operation of the singlechip, so the frequency and the duty ratio of the output back-cut dimming PWM signals are very accurate and stable. However, this method has a disadvantage that, since the output PWM signal is continuously output once the hardware PWM has given frequency and duty ratio, the frequency and duty ratio of the PWM signal are precisely controlled in timing to obtain a hardware PWM signal of one period to control the half-wave of the sine wave after the fet is switched to zero. Although good, this dimming approach has the disadvantage of requiring a timed and precise PWM control to intercept a PWM signal for one cycle, and once this timed interrupt is interrupted by a higher level of interrupt, the intercepted hardware PWM signal may overflow a sinusoidal ac half-wave, which may be uncontrolled near the zero crossing, indicating a glitch at minimum brightness.

Disclosure of Invention

The invention provides a single-pulse silicon controlled rectifier back-phase-cut dimming method and a dimmer.

According to a first aspect of the present invention, the present invention provides a single-pulse silicon controlled rectifier back-cut phase dimming method, comprising the following steps: the control unit receives a zero-crossing pulse signal of the alternating sine wave generated by the zero-crossing detection unit, generates an external trigger event when the edge jump of the zero-crossing pulse signal is detected, starts an internal counter according to the external trigger event, and outputs a high level to the driving unit when the count of the counter reaches a preset comparison value to control the driving unit to be started; the counter continues counting, when the count of the counter reaches an automatic loading value, a low level is output to the driving unit, the driving unit is controlled to be closed, the count of the counter is cleared and stopped, and a next external trigger event is waited; the automatic loading value is a reference value corresponding to the dimming signal value.

Preferably, the reference value is a result value calculated by the dimming signal value according to a data gamma curve algorithm.

According to a second aspect of the present invention, the present invention provides a single-pulse silicon controlled rectifier trailing edge dimmer, comprising an input unit, a zero-crossing detection unit, a driving unit, a control unit and a power supply unit for supplying power to the control unit, wherein the control unit is configured to receive a dimming signal, the input unit is configured to output an ac sine wave signal, the input unit, the zero-crossing detection unit and the control unit are sequentially connected, and the input unit and the control unit are further connected to the driving unit respectively; the control unit is configured to: receiving a zero-crossing pulse signal of an alternating sine wave generated by a zero-crossing detection unit, generating an external trigger event when the edge jump of the zero-crossing pulse signal is detected, starting an internal counter according to the external trigger event, and outputting a high level to a driving unit to control the driving unit to be started when the count of the counter reaches a preset comparison value; the counter continues counting, when the count of the counter reaches an automatic loading value, a low level is output to the driving unit, the driving unit is controlled to be closed, the count of the counter is cleared and stopped, and a next external trigger event is waited; the automatic loading value is a reference value corresponding to the dimming signal value.

Preferably, the lighting control system further comprises a potentiometer dimming unit or a wireless remote control unit connected with the control unit, and the dimming signal is sent by the potentiometer dimming unit or the wireless remote control unit.

Preferably, the input unit further includes a protection circuit.

Preferably, the power supply unit is connected with the output end of the input unit, and the power supply unit comprises a rectifying circuit and a voltage stabilizing circuit.

Preferably, the control unit comprises a single chip microcomputer STM 8S.

The invention has the beneficial effects that: in conventional PWM dimming, the frequency of the PWM is fixed, and dimming is performed by changing the duty cycle of the signal. The invention controls the driving unit to be opened or closed according to the automatic loading value, so that the duty ratio is fixed, the frequency is changed according to the dimming signal, single-pulse dimming is formed, the influence of high-level interruption is avoided, and the dimming mode is stable and reliable.

Drawings

Fig. 1 is a schematic structural diagram of a single-pulse scr post-phase-cut dimmer according to an embodiment of the present invention;

FIG. 2 is a waveform diagram of an AC sinusoidal signal according to an embodiment of the present invention;

FIG. 3 is a waveform diagram of a zero-crossing pulse signal according to an embodiment of the present invention;

FIG. 4 is a waveform diagram illustrating a single pulse mode according to an embodiment of the present invention;

FIG. 5 is a waveform diagram of a single pulse in accordance with one embodiment of the present invention;

fig. 6 is a schematic waveform diagram of an output of a driving unit according to an embodiment of the invention.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings.

Before the present invention is explained in detail, it is necessary to explain a circuit to which the present invention is applied, and as shown in fig. 1, an input unit 1 outputs an alternating sinusoidal current, and a zero-crossing detection unit 2 performs zero-crossing detection of the alternating sinusoidal signal to generate a zero-crossing pulse signal. The control unit 3 receives the zero-crossing pulse signal and the dimming signal, outputs a control signal to the driving unit 4, controls the driving unit 4 to be turned on or turned off, and further outputs the dimming signal. The control unit 3 may be a single chip microcomputer specifically, hereinafter, a description will be given by taking the single chip microcomputer STM8S as an example, and naturally, the control unit 3 may also be another single chip microcomputer or another chip according to actual needs. Because of the need to generate a monopulse waveform, the single chip microcomputer STM8S needs to be configured in monopulse mode, which allows the counter to respond to a stimulus and produce a pulse with a controllable pulse width after a programmable delay. The counter may be started by a clock/trigger controller to generate a waveform in an output compare mode or a PWM mode. Setting the OPM bit of the TIM1_ CR1 register will select the monopulse mode, at which time the counter automatically stops at the next update event UEV. When the comparison value is different from the initial value of the counter, a pulse is generated. The method provided by the embodiment is set to the single-pulse mode by default.

The embodiment of the invention provides a single-pulse silicon controlled rectifier phase-cut dimming method, which is discussed from the view angle of a control unit based on the circuit and specifically comprises the following steps:

the input unit outputs an ac sinusoidal power supply, which may be 110V or 220V ac power supply, and as shown in fig. 2, the waveform of the output signal is a sine wave. The zero-crossing detection unit 2 performs zero-crossing detection to generate a corresponding zero-crossing pulse signal, as shown in fig. 3, when the ac sinusoidal signal crosses zero, the level of the pulse signal changes, and a zero-crossing pulse signal matched with the ac sinusoidal signal is formed. The control unit receives the zero-crossing pulse signal generated by the zero-crossing detection unit.

The control unit detects the waveform change of the zero-crossing pulse signal in real time, and generates an external trigger event when the edge jump of the zero-crossing pulse signal is detected, namely the rising edge or the falling edge of the zero-crossing pulse signal is generated. An internal channel IC2 of the single chip may be configured to detect the edge transition and use IC2 as a trigger source (TRGI) of the clock/trigger controller to start the counter. Thus, an internal counter is started to count according to an external trigger event. Setting the output port of the control unit to rising edge trigger, the auto-load value TIM1_ ARR and the compare value TIM1_ CCR1 may be preset, and the auto-load value TIM1_ ARR should be greater than the compare value TIM1_ CCR 1. As shown in FIG. 4, the delay time tDELAY is defined by the TIM1_ CCR1 value, while the width tPULSE of a single pulse is defined by the difference between the auto-load value and the compare value (TIM1_ ARR-TIM 1_ CCR 1).

Along with the counting of the counter, when the counting of the counter reaches a preset comparison value, a high level is output to the driving unit, the driving unit is controlled to be started, and then the sine wave signal of the input unit is loaded on the lamp to be dimmed through the driving unit. And (3) with the continuous counting of the counter, when the counting of the counter reaches an automatic loading value, outputting a low level to the driving unit, controlling the driving unit to be closed, at the moment, cutting off the sine wave signal of the input unit, so that the sine wave signal cannot be loaded on the lamp to be dimmed, and stopping counting and resetting the counter. Since the zero-crossing pulse signal maintains a level value for a half-period, the control drive unit will be continuously turned off until the half-period of the zero-crossing pulse signal is over. The control unit will wait for the next external trigger event and start the control of the next cycle. Wherein, the comparison value is kept fixed, so that the output signals keep relatively consistent duty ratio. The auto-loading value is a reference value corresponding to the dimming signal value, and the auto-loading value is changed by the dimming signal value, so that the width of the single pulse is determined by the dimming signal. As shown in fig. 5, the single pulse signal is formed within a half of the zero-crossing pulse period. Finally, the waveform outputted by the driving unit is as shown in fig. 6, which shows the process from dark to brightest and from brightest to dark, and from the output waveform of the driving unit, the rear part of the waveform after the zero crossing point of the sine alternating current is chopped, and the front part is kept intact, so as to achieve the dimming effect. The dimming mode is not influenced by high-level interruption and is stable and reliable.

The following programs can be configured for a hardware PWM single-pulse mode of the singlechip STM 8S:

//PWMset

TIM1 — CR1 — 0x 00; // close timer

TIM1_ IER — 0x 00; // close interrupt

TIM1_PSCRH＝0；

TIM1_ PSCRL ═ 3; //4M clock PWM

TIM1_ARRH＝0x8E； //PWMfreq8E0C/110Hz

TIM1_ARRL＝0x0C；

TIM1 — CCR1H — 0x 01; // duty cycle coefficient: duty ratio-duty ratio coefficient/reload value

TIM1_CCR1L＝0x00；

TIM1_ CCER1 — 0x 01; // channel 1: turn on the output

TIM1_ CCMR1 — 0x 78; // PWM mode 2; channel 1PWM output// 0x78 or 0x68

TIM1_ CCMR2| ═ 0x 01; // trigger mode: channel 2 as a trigger input, maps to TI2FP2

TIM1_ CCER1& (1< < 5); // channel 2 output polarity: high level active

TIM1_ SMCR | ═ 0x 66; // trigger selection: TI2FP2 trigger mode: flip-flop input rising edge triggering

TIM1_ BKR &0 xEC; // CC polarity locked clear

TIM1_ BKR | ═ 0x 80; // Master Enable

TIM1 — CR1 — 0x 89; // count Enable

TIM1 — EGR | ═ 1; v/clearing the counter and waiting for the next trigger event

The reference value is specifically a result value calculated by the dimming signal value according to the data gamma curve algorithm, and in an initial state, the auto load value is assigned with an initial value, such as the program code mentioned above, and the auto load value ARR is assigned with 0x8E0C, which is only a temporary value, and when the control unit receives the dimming signal, the auto load value will change with the dimming signal value.

The dimming signal value is changed between 0 and 255, the dimming signal value 0 to 255 corresponds to a result value according to a data gamma curve algorithm, the result value and the dimming signal value have a corresponding table, and the control unit converts the dimming signal value into an automatic loading value of 16-bit hardware PWM through table lookup and further controls the driving unit.

The embodiment of the invention also provides a single-pulse silicon controlled rectifier phase-cut dimmer, which comprises an input unit 1, a zero-crossing detection unit 2, a driving unit 4, a control unit 3 and a power supply unit 5 for supplying power to the control unit 3, wherein the control unit 3 is used for receiving dimming signals, the input unit 1 is used for outputting alternating-current sine wave signals, the input unit 1, the zero-crossing detection unit 2 and the control unit 3 are sequentially connected, and the input unit 1 and the control unit 3 are also respectively connected with the driving unit 4. The control unit is configured to: receiving a zero-crossing pulse signal of an alternating sine wave generated by a zero-crossing detection unit, generating an external trigger event when the edge jump of the zero-crossing pulse signal is detected, starting an internal counter according to the external trigger event, and outputting a high level to a driving unit to control the driving unit to be started when the count of the counter reaches a preset comparison value; the counter continues counting, when the count of the counter reaches an automatic loading value, a low level is output to the driving unit, the driving unit is controlled to be closed, the count of the counter is cleared and stopped, and a next external trigger event is waited; the automatic loading value is a reference value corresponding to the dimming signal value. Wherein, the reference value is a result value calculated by the dimming signal value according to a data gamma curve algorithm. The control unit may be configured to generate an external trigger event upon detection of an edge transition of the zero-crossing pulse signal. The above dimmer can be described with reference to the foregoing embodiments of the single-pulse triac trailing-phase dimming method.

The source of the dimming signal will be explained below, and in one embodiment, the dimming signal further includes a potentiometer dimming unit 61 connected to the control unit 3, and the dimming signal is generated by the potentiometer dimming unit 61 and sent to the control unit 3. The potentiometer adopts AD sampling input for dimming, the single chip microcomputer carries out analog-to-digital conversion on 0-5V dimming voltage on the adjustable potentiometer to obtain 10-bit AD data, and the 10-bit AD data is converted into 8-bit dimming data through software data, so that the 8-bit single chip microcomputer can carry out operation and control conveniently.

In another embodiment, the lighting system further comprises a wireless remote control unit 62 connected to the control unit 3, and the dimming signal is generated by the wireless remote control unit 62 and is transmitted to the control unit 3. The single chip microcomputer receives the wireless signal sent by the wireless remote control unit 62 through the wireless receiving module, and performs timing software decoding on the received control data sequence, so as to obtain a control instruction and dimming data.

In the above embodiment, the input unit 1 may be directly connected to a mains supply to output a 220v voltage signal, and may specifically include a protection circuit to perform an overvoltage protection function and prevent a back-end circuit from being damaged. And the power supply unit 5 is connected with the output end of the input unit 1, and the power supply unit 5 comprises a rectifying circuit and a voltage stabilizing circuit. Thereby outputting a stable voltage as an operating voltage of the control unit 3.

The foregoing is a more detailed description of the present invention that is presented in conjunction with specific embodiments, and the practice of the invention is not to be considered limited to those descriptions. It will be apparent to those skilled in the art that a number of simple derivations or substitutions can be made without departing from the inventive concept.

Claims

1. A single-pulse silicon controlled rectifier back phase-cut dimming method is characterized by comprising the following steps:

the control unit receives a zero-crossing pulse signal of the alternating sine wave generated by the zero-crossing detection unit, generates an external trigger event when the edge jump of the zero-crossing pulse signal is detected, starts an internal counter according to the external trigger event, and outputs a high level to the driving unit when the count of the counter reaches a preset comparison value to control the driving unit to be started; the counter continues counting, when the count of the counter reaches an automatic loading value, a low level is output to the driving unit, the driving unit is controlled to be closed, the count of the counter is cleared and stopped, and a next external trigger event is waited; the automatic loading value is a reference value corresponding to the dimming signal value, the automatic loading value is changed by the dimming signal value, the width of the single pulse is determined by the dimming signal, and the reference value is a result value calculated by the dimming signal value according to a data gamma curve algorithm.

2. The utility model provides a monopulse silicon controlled rectifier back phase-cut dimmer which characterized in that:

the dimming circuit comprises an input unit, a zero-crossing detection unit, a driving unit, a control unit and a power supply unit for supplying power to the control unit, wherein the control unit is used for receiving dimming signals, the input unit is used for outputting alternating current sine wave signals, the input unit, the zero-crossing detection unit and the control unit are sequentially connected, and the input unit and the control unit are also respectively connected with the driving unit; the control unit is configured to: receiving a zero-crossing pulse signal of an alternating sine wave generated by a zero-crossing detection unit, generating an external trigger event when the edge jump of the zero-crossing pulse signal is detected, starting an internal counter according to the external trigger event, and outputting a high level to a driving unit to control the driving unit to be started when the count of the counter reaches a preset comparison value; the counter continues counting, when the count of the counter reaches an automatic loading value, a low level is output to the driving unit, the driving unit is controlled to be closed, the count of the counter is cleared and stopped, and a next external trigger event is waited; the automatic loading value is a reference value corresponding to the dimming signal value, the automatic loading value is changed by the dimming signal value, the width of the single pulse is determined by the dimming signal, and the reference value is a result value calculated by the dimming signal value according to a data gamma curve algorithm.

3. The single-pulse thyristor trailing edge dimmer of claim 2, wherein:

the light modulation signal is sent by the potentiometer light modulation unit or the wireless remote control unit.

4. The single-pulse thyristor trailing edge dimmer of claim 2, wherein:

the input unit further includes a protection circuit.

5. The single-pulse thyristor trailing edge dimmer of claim 2, wherein:

the power supply unit is connected with the output end of the input unit and comprises a rectifying circuit and a voltage stabilizing circuit.

6. The single-pulse thyristor trailing edge dimmer of claim 2, wherein:

the control unit comprises a single chip microcomputer STM 8S.