Apparatus and method for driving semiconductor light-emitting device assembly

1. A driving apparatus for driving a semiconductor light-emitting device assembly, comprising:

a driving unit configured to drive the semiconductor light-emitting device assembly;

a constant-current control unit configured to sample a current average value of the semiconductor light-emitting device assembly and control the driving unit according to the current average value, and

a cycle by cycle control unit comprising:

a sampling circuit configured to sample a current instantaneous value of the driving unit or the semiconductor light-emitting device assembly; and

an adjusting circuit configured to adjust an output of the driving unit when the current instantaneous value sampled by the sampling circuit is not less than a preset reference value,

wherein when the current instantaneous value sampled by the sampling circuit is not less than a preset reference value, the driving unit is controlled by the constant-current control unit and the cycle by cycle control unit; and

when the current instantaneous value sampled by the sampling circuit is less than the preset reference value, the driving unit is controlled by the constant-current control unit.

2. The driving apparatus according to claim 1 , wherein the semiconductor light-emitting device assembly comprises more than one strings of semiconductor light-emitting devices connected in parallel.

3. The driving apparatus according to claim 2 , wherein each string of the semiconductor light-emitting device comprises a filter capacitor, a protection circuit and a LED string, and the filter capacitor and the protection circuit are respectively connected in parallel to two ends of the LED string.

4. The driving apparatus according to claim 1 , wherein a sampling point from which the sampling circuit samples the current instantaneous value is the same as a sampling point from which the constant-current control unit samples the current average value.

5. The driving apparatus according to claim 1 , wherein a sampling point from which the sampling circuit samples the current instantaneous value is different from a sampling point from which the constant-current control unit samples the current average value.

6. The driving apparatus according to claim 1 , wherein the driving unit comprises a first switch, a second switch, a resonant circuit and a transformer;

the first switch is connected with the second switch in series;

one end of the resonant circuit is connected to a connection point between the first switch and the second switch, and the other end of the resonant circuit is connected to one end of a primary side of the transformer;

the other end of the primary side of the transformer is connected to one end of the second switch which is not connected to the first switch.

7. The driving apparatus according to claim 1 , wherein the sampling circuit comprises a first resistor and a second resistor connected in series, and one end of the first resistor is connected to a sampling point for sampling currents, the other end of the first resistor is connected to one end of the second resistor, and the other end of the second resistor is grounded.

8. The driving apparatus according to claim 7 , wherein the adjusting circuit comprises a third resistor and a transistor;

an emitter of the transistor is grounded, a base of the transistor is connected to a connection point between the first resistor and the second resistor, a collector of the transistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the driving unit.

9. The driving apparatus according to claim 7 , wherein the adjusting circuit comprises a digital signal processing unit of which an input terminal is connected to a connection point between the first resistor and the second resistor and an output terminal is connected to the driving unit.

10. The driving apparatus according to claim 1 , wherein the adjusting circuit is configured to adjust the output of the driving unit when the current instantaneous value sampled by the sampling circuit is not less than the preset reference value, so as to limit a current peak of the semiconductor light-emitting device assembly.

11. The driving apparatus according to claim 10 , wherein the adjusting circuit is configured to limit the current peak of the semiconductor light-emitting device assembly by adjusting an operating frequency of the driving unit.

12. The driving apparatus according to claim 10 , wherein the adjusting circuit is configured to limit the current peak of the semiconductor light-emitting device assembly by adjusting a duty cycle of the driving unit.

13. The driving apparatus according to claim 1 , wherein the driving unit is a forward circuit, a flyback circuit, a half-bridge switching circuit or a full bridge switching circuit.

14. A method for driving a semiconductor light-emitting device assembly by using a driving apparatus, the driving apparatus comprising a driving unit configured to drive the semiconductor light-emitting device assembly; a constant-current control unit configured to sample a current average value of the semiconductor light-emitting device assembly and control the driving unit according to the current average value; and a cycle by cycle control unit comprising: a sampling circuit configured to sample a current instantaneous value of the driving unit or the semiconductor light-emitting device assembly; and an adjusting circuit configured to adjust an output of the driving unit when the current instantaneous value sampled by the sampling circuit is not less than a preset reference value, wherein the method comprises:

sampling, by the sampling circuit, a current instantaneous value of the driving unit or the semiconductor light-emitting device assembly;

comparing the current instantaneous value with the preset reference value;

adjusting, by the adjusting circuit, the output of the driving unit when the current instantaneous value is not less than the preset reference value; and

driving the semiconductor light-emitting device assembly according to the output of the driving unit,

wherein when the current instantaneous value sampled by the sampling circuit is not less than the preset reference value, the driving unit is controlled by the constant-current control unit and the cycle by cycle control unit; and

when the current instantaneous value sampled by the sampling circuit is less than the preset reference value, the driving unit is controlled by the constant-current control unit.