LED constant-current driving method and device based on linearity and PWM operating mode
A working mode and constant current drive technology, which is applied to lighting devices, lamp circuit layout, light sources, etc., can solve the problems of small fluctuations in power supply voltage, device heating, and efficiency decline, and achieve no inductive components, simple circuit structure, and solution The effect of high power consumption
Active Publication Date: 2016-02-17
王汉忠
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Problems solved by technology
[0003] 1. The linear constant current driver works in the linear mode and is used in series with the load (LED light source). It controls the load current by adjusting its own voltage drop to achieve the purpose of constant current. The voltage drop of the linear constant current driver itself depends on the The reactive power generated will cause the device to heat up and the efficiency will drop. In the application, a light source with high voltage, low current and low dropout voltage must be selected, so the application is limited to a certain extent.
[0004] 2. The fluctuation range of the power supply voltage allowed by the linear constant current driver is relatively small. Once the fluctuation range of the power supply exceeds the allowable range, the efficiency will drop or even affect the normal operation.
[0005] 3. The existing LED light source is generally composed of several LED chips or lamp beads in series. The forward voltage of a single LED is about 3.2V. If a linear drive scheme is used, the manufacturer will generally increase the number of lamp beads. Increase the voltage of the light string, reduce the pressure difference, or use higher-priced high-voltage lamp beads, which will increase the cost of the product
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[0023] refer to figure 1 , figure 2 , a LED constant current driving method based on linear and PWM working modes. Under the framework of linear constant current, PWM control technology is used to control the current of LED load by changing the duty cycle of the pulse waveform after rectification of alternating current.
[0024] Sampling the pulse waveform after AC rectification, and the pulse controller generates a group of pulse signals that are cycle-synchronous and of the same frequency as the rectified pulse waveform, and control the on-off of the semiconductor power device connected in series with the LED load by changing the duty cycle time to make the LED load current constant.
[0025] The pulse controller generates a set of square wave signals with controllable duty ratio, and modulates the rectified DC pulse waveform, and controls the on-off time of the semiconductor power device connected in series with the LED load by modulating the duty ratio of the pulse, so t...
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The invention discloses an LED constant-current driving method and device based on linearity and a PWM operating mode. According to the method, under the framework of linear constant currents, a PWM control technology is adopted, and the current of an LED load is controlled by changing the duty ratio of an impulse waveform obtained after rectification of alternating currents; as a result, the calorific value of a power device can be reduced, conversion efficiency can be improved, the defects of high reactive power consumption, a small allowable power voltage fluctuation range, low conversion efficiency and the like of linear constant-current driving in the prior art are effectively overcome, and the LED constant-current driving method and device have the advantages that the circuit structure is simple, inductance elements are not needed, manufacture cost is low, and EMI is not adopted.
Description
technical field [0001] The invention relates to a lighting lamp driving power supply, in particular to a LED constant current driving method and device. Background technique [0002] In LED lighting fixtures powered by AC220V / 50Hz mains power, the high-voltage linear constant current drive scheme has been widely used. The linear constant current drive has the advantages of simple structure, low cost, no electromagnetic radiation, and high reliability. It has been recognized by the industry. However, the linear constant current driver also has the following unavoidable defects: [0003] 1. The linear constant current driver works in the linear mode and is used in series with the load (LED light source). It controls the load current by adjusting its own voltage drop to achieve the purpose of constant current. The voltage drop of the linear constant current driver itself depends on the The reactive power generated will cause the device to heat up and the efficiency will drop. ...
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IPC IPC(8): H05B37/02
CPCY02B20/40
Inventor 王汉忠
Owner 王汉忠