Soft-switching multi-channel dimmable LED driver and driving method thereof

Abstract

The application discloses a soft-switching multi-channel adjustable light LED driver, which comprises a direct-current power supply V in , a switch tube S1, a switch tube S2, a resonant capacitor C r1 , a resonant capacitor C r2 , a common inductor L s , a first full-wave rectification double-current equalization unit and a second full-wave rectification double-current equalization unit. The application also discloses a soft-switching multi-channel adjustable light LED driving method. The application adopts a common inductor as the resonant inductor of two resonant cavities, and does not adopt a transformer, so that the number of magnetic elements is reduced, and the power density is improved. The switch tubes can all realize zero-voltage turn-on, the switching loss is greatly reduced, and the efficiency is high. Four current outputs can be realized, two of which form a group to realize dimming, and the application is suitable for occasions of multi-color lighting application.

Description

Technical Field

[0001] This invention relates to the field of LED driver control, specifically to a soft-switching multi-channel dimmable LED driver, and also to a soft-switching multi-channel dimmable LED driving method, applicable to fields such as power electronics. Background Technology

[0002] With societal development, energy efficiency in lighting products has become crucial. Light-emitting diodes (LEDs) are widely used in LCD backlighting, residential, industrial, and signal applications due to their long lifespan, high luminous efficacy, and diverse colors. However, in multi-output LED drivers for dimmable lighting systems and color mixing applications, some topologies can only drive loads with the same voltage and current. While some can achieve independent dimming, they increase the converter size and number of components, and the switching is hard switching. Although LLC resonant converters for LED multi-color lighting offer soft switching and high efficiency, the presence of a transformer affects the dimming range due to the transformer's turns ratio. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned problems in the prior art by providing a soft-switching multi-channel dimmable LED driver and a soft-switching multi-channel dimmable LED driving method. This invention achieves four current outputs with only two switching transistors, one common inductor, two resonant capacitors, and eight diodes. The currents of output load LED1 and LED2 are shared, as are the currents of output load LED3 and LED4. Output load LED1 and LED2 are used for one dimming channel, while output load LED3 and LED4 are used for the other. Simultaneously, it enables zero-voltage turn-on of all switching transistors and zero-current turn-off of the diodes.

[0004] The above-mentioned objectives of the present invention are achieved through the following technical means:

[0005] A soft-switching multi-channel dimmable LED driver includes a DC power supply V in It also includes switching transistor S1, switching transistor S2, and resonant capacitor C. r1 Resonant capacitor C r2 Common inductor L s The first full-wave rectifier dual-path current sharing unit and the second full-wave rectifier dual-path current sharing unit, DC input power supply V in The positive terminals are connected to the drain of the switching transistor S1 and the resonant capacitor C, respectively. r1 The positive terminal, resonant capacitor C r1 The negative terminal is connected to the positive terminal of the first full-wave rectifier dual-path current sharing unit. The source of switch S1 and the drain of switch S2 are both connected to the common inductor L. s The positive terminal is connected, and the common inductor Ls The negative terminals of the transistors are connected to the negative terminals of the first full-wave rectifier dual-path current sharing unit and the positive terminals of the second full-wave rectifier dual-path current sharing unit, respectively. The source terminal of the switching transistor S2 is connected to the DC input power supply V. in The negative terminal and resonant capacitor C r2 The negative terminal is connected, and the resonant capacitor C r2 The positive terminal is connected to the negative terminal interface of the two full-wave rectifier dual-path current sharing units.

[0006] As described above, the first full-wave rectifier dual-path current sharing unit includes freewheeling diodes D1, D2, D3, and D4, and a filter capacitor value C. o1 Filter capacitor value C o2 Output load LED1 and output load LED2

[0007] The positive terminal of the first full-wave rectifier dual-path current sharing unit is connected to the cathode of freewheeling diode D1 and the anode of freewheeling diode D2, respectively. The cathode of freewheeling diode D2 is connected to the anode of output load LED1. The cathodes of output load LED1, D4, and LED2 are all connected to the anode of freewheeling diode D1. The anode of output load LED2 is connected to the cathode of freewheeling diode D3. The anodes of freewheeling diode D3 and D4 are both connected to the negative terminal of the first full-wave rectifier dual-path current sharing unit. A filter capacitor with a value of C is connected in parallel between the anode and cathode of output load LED1. o1 The output load LED2 has a filter capacitor with value C connected in parallel between its anode and cathode. o2 .

[0008] As described above, the second full-wave rectifier dual-path current sharing unit includes freewheeling diodes D5, D6, D7, and D8, and a filter capacitor value C. o3 Filter capacitor value C o4 Output load LED3 and output load LED4

[0009] The negative terminal of the second full-wave rectifier dual-path current sharing unit is connected to the cathode of freewheeling diode D7 and the anode of freewheeling diode D8, respectively. The cathode of freewheeling diode D8 is connected to the anode of output load LED4. The cathodes of output load LED4, D7, and LED3 are all connected to the anode of freewheeling diode D6. The anode of output load LED3 is connected to the cathode of freewheeling diode D5. The anodes of freewheeling diode D5 and D6 are both connected to the positive terminal of the second full-wave rectifier dual-path current sharing unit. A filter capacitor with value C is connected in parallel between the anode and cathode of output load LED3. o3 The output load LED4 has a filter capacitor with value C connected in parallel between its anode and cathode.o4 .

[0010] A soft-switching multi-channel dimmable LED driving method includes the following modes in one switching cycle:

[0011] Mode 1 begins and ends at times t0 and t1, respectively. When switch S1 is turned on, mode 1 begins at time t0. Switch S2 is turned off, and the drain-source voltage of switch S2 is equal to the input power supply voltage V. in The instantaneous current i of the common inductor Ls Ls The voltage rises linearly under forward bias and freewheels through the body diode of switch S1, making the drain-source voltage of switch S1 zero, thus providing zero-voltage turn-on for switch S1. The resonant capacitor C... r1 The resonant current I on cr1 and resonant capacitor C r2 The resonant current I on cr2 When the resonance reaches zero, freewheeling diodes D2, D4, D6, and D8 conduct, while freewheeling diodes D1, D3, D5, and D7 achieve zero-current turn-off. When the common inductor L... s instantaneous current i Ls When it rises to 0, it enters mode 2.

[0012] Mode 2, with start and end times t1 and t2, i Ls i cr1 and i cr2 Defined as common inductance L s Resonant capacitor C r1 and resonant capacitor C r2 The instantaneous current flowing through i Ls =0, i Cr1 =0, i Cr2 When = 0, mode 2 starts at time t1, and the drain-source voltage of switch S2 is equal to the input power supply V. in Public inductor L s instantaneous current i Ls The linear increase, while the resonant capacitance C r2 Charging begins, resonant capacitor C r1 For input power supply V in Slow discharge occurs, freewheeling diodes D5 and D7 are turned on, while freewheeling diodes D1, D2, D3, D4, D6, and D8 are reverse-biased and cut off, entering mode 3.

[0013] Mode 3, with start and end times t2 and t3, respectively. At time t2, the common inductance L... s instantaneous current i Ls Before the switching transistor S2 turns on when the peak value is reached, the common inductance L s instantaneous current i LsThe parasitic capacitance and resonant capacitance C of the switching transistor S1 r2 Slow charging, common inductor L s instantaneous current i Ls The parasitic capacitance and resonant capacitance C of the switching transistor S2 r1 Discharge begins, freewheeling diodes D1, D3, D5, and D7 conduct, while freewheeling diodes D2, D4, D6, and D8 are reverse-biased and cut off. When the drain-source voltage of switch S2 drops to zero, the body diode of switch S2 turns on, entering mode 4.

[0014] Mode 4 begins and ends at times t3 and t4. When switch S2 is turned on, mode 4 starts at time t3, and the common inductance L... s instantaneous current i Ls The voltage drops linearly under reverse voltage and freewheels through the body diode of switch S2, making the drain-source voltage of switch S2 zero, thus providing zero-voltage turn-on for switch S2. The resonant capacitor C... r1 The resonant current I on cr1 and resonant capacitor C r2 The resonant current I on cr2 When the resonance reaches zero, freewheeling diodes D1, D3, D5, and D7 conduct, while freewheeling diodes D2, D4, D6, and D8 achieve zero-current turn-off, entering mode 5.

[0015] Mode 5, with start and end times t4 and t5, when the common inductance L... s instantaneous current i Ls =0, i Cr1 =0, i Cr2 When = 0, mode 5 starts at time t4, and the drain-source voltage of switch S1 is equal to the input power supply V. in Public inductor L s instantaneous current i Ls After time t3, it becomes negative and decreases linearly, indicating the resonant capacitance C. r2 For common inductor L s Charging, input power V in For resonant capacitor C r1 During slow charging, freewheeling diodes D6 and D8 are turned on, while freewheeling diodes D1, D2, D3, D4, D5, and D7 are reverse-biased and cut off. When the common inductor L... s instantaneous current i Ls When the value drops to 0, mode 5 ends.

[0016] Mode 6 begins and ends at times t5 and t6. At time t6, before switch S1 is turned on, the common inductance L... s instantaneous current i Ls The inductance continues to decrease linearly until it reaches its peak value, with the common inductance L...s instantaneous current iL s The parasitic capacitance and resonant capacitance C of the switching transistor S2 r1 Charging, common inductor L s instantaneous current iL s For the parasitic capacitance of switching transistor S1, the common inductance L s instantaneous current iL s For resonant capacitor C r2 Discharge occurs, freewheeling diodes D2, D4, D6, and D8 conduct, while freewheeling diodes D1, D3, D5, and D7 are reverse-biased and cut off. When the drain-source voltage of switching transistor S1 drops to zero, the body diode of switching transistor S1 turns on, and the next switching cycle begins.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention uses a common inductor as the resonant inductor of the two resonant cavities, and there is no transformer, the number of magnetic components is reduced, and the power density is improved.

[0019] (2) All the switching transistors of the present invention can achieve zero voltage turn-on, and the diodes can achieve zero current turn-off, greatly reducing switching losses and increasing efficiency.

[0020] (3) The present invention can adopt a control strategy with a fixed duty cycle or a fixed frequency, which is simple to control.

[0021] (4) The present invention can realize four-channel current output, with the current of output load LED1 and output load LED2 being equal, the current of output load LED3 and output load LED4 being equal, output load LED1 and output load LED2 being used as one dimming channel, and output load LED3 and output load LED4 being used as another dimming channel. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the circuit structure of a soft-switching multi-channel dimmable LED driver.

[0023] Figure 2(a) is a schematic diagram of mode 1.

[0024] Figure 2(b) is a schematic diagram of mode 2.

[0025] Figure 2(c) is a schematic diagram of mode 3.

[0026] Figure 2(d) is a schematic diagram of mode 4.

[0027] Figure 2(e) is a schematic diagram of mode 5.

[0028] Figure 2(f) is a schematic diagram of mode 6;

[0029] Figure 3 This is a schematic diagram of the equivalent circuit of a soft-switching multi-channel dimmable LED driver.

[0030] Figure 4(a) shows the waveforms of the voltage across the switching transistor of the present invention under rated load and the amplitude of the drive signal amplified by 20 times. The horizontal axis represents time, and the vertical axis represents voltage.

[0031] Figure 4(b) shows the waveform of the output current of the switching transistor under a balanced load. The horizontal axis represents time, and the vertical axis represents current.

[0032] Figure 4(c) shows the waveforms of the reverse voltage of the freewheeling diode D1, the reverse voltage of the freewheeling diode D2, the current amplification of the freewheeling diode D1 by 5 times, and the current amplification of the freewheeling diode D2 by 5 times. The horizontal axis represents time, and the vertical axis represents voltage.

[0033] Figure 4(d) shows the waveforms of the reverse voltage of the freewheeling diode D3, the reverse voltage of the freewheeling diode D4, the current amplification of the freewheeling diode D3 by 5 times, and the current amplification of the freewheeling diode D4 by 5 times. The horizontal axis represents time, and the vertical axis represents voltage.

[0034] Figure 4(e) shows the waveforms of the reverse voltage of the freewheeling diode D5, the reverse voltage of the freewheeling diode D6, the current amplification of the freewheeling diode D5 by 2 times, and the current amplification of the freewheeling diode D6 by 5 times. The horizontal axis represents time, and the vertical axis represents voltage.

[0035] Figure 4(f) shows the waveforms of the reverse voltage of the freewheeling diode D7, the reverse voltage of the freewheeling diode D8, the current amplification of the freewheeling diode D7 by 3 times, and the current amplification of the freewheeling diode D8 by 3 times. The horizontal axis represents time, and the vertical axis represents voltage.

[0036] Figure 4(g) shows the waveform of the output current of the switching transistor of the present invention under an unbalanced load. The horizontal axis represents time, and the vertical axis represents current. Detailed Implementation

[0037] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to examples. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0038] For ease of explanation and analysis later, the definitions of parameters such as voltage and current representing circuit elements are as follows:

[0039] A soft-switching multi-channel dimmable LED driver with a power input voltage of V in , direction as Figure 3 D is defined as the duty cycle of the power switch S1 during its on-time; T is defined as the time of one switching cycle; DT sDefined as the product of the duty cycle D of the power switch's on-time and the time of one switching cycle; T r1 and T r2 f is defined as the time of one resonant cycle between the first and second resonant cavities; r1 and f r2 The resonant frequencies of the first and second resonant cavities are defined respectively; f s Defined as switching frequency; w s1 w s2 V is defined as the angular frequency of the first resonant cavity and the second resonant cavity, respectively. s1 and V s2 These are the source voltages of power switches S1 and S2, respectively, V d1 and V d2 These are the drain voltages of power switching transistors S1 and S2, respectively, V ds1 and V ds2 These are the drain-source voltages of power switches S1 and S2, respectively, both in the direction from drain to source; V g1 and V g2 These are defined as the gate drive signals for power switches S1 and S2, respectively; V EC1 and V EC2 Defined respectively as AC equivalent output load R ac1 The voltage and AC equivalent output load R ac2 The voltage, direction as Figure 3 V AB and V BC I is defined as the equivalent input voltage of the first resonant cavity and the second resonant cavity, respectively; m1 I m2 and I m The common inductance L flowing through the first resonant cavity and the second resonant cavity are defined respectively. s and common inductor L s The peak value of the average current on the surface, with the direction defined as positive from left to right, as shown in the figure. Figure 3 i Ls1 and i Ls2 The common inductance L flowing through the first and second resonant cavities are defined respectively. s The instantaneous current on the circuit is defined as positive from left to right; i Ls i cr1 and i cr2 Defined as common inductance L s Resonant capacitor C r1 and resonant capacitor C r2 The instantaneous current flowing through it, in the direction of... Figure 3 By analogy; V cr1 and V cr2 Defined as resonant capacitor Cr1 and resonant capacitor C r2 The voltage across the two ends, in the direction of... Figure 1 VD1~VD8 are defined as the voltages across the freewheeling diodes D1~D8, and ID1~ID8 are defined as the currents across the freewheeling diodes D1~D8, with the directions as follows: Figure 3 Similarly, VLED1~VLED4 are defined as the output voltages across the output loads LED1~LED4, with the direction as follows: Figure 3 By analogy; ILED1~ILED4 are defined as the average output current on the output loads LED1~LED4, iLED j Defined as the instantaneous output current on the output loads LED1~LED4, with the direction in the same direction as VLED1~VLED4; ΔQ1dis and ΔQ2dis are defined as the resonant capacitance C within one switching cycle. r1 and resonant capacitor C r2 The amount of charge discharged; ΔQ1ch and ΔQ2ch are defined as the resonant capacitance C within one switching cycle. r1 and resonant capacitor C r2 The amount of charge during charging.

[0040] A soft-switching multi-channel dimmable LED driver, circuit diagram as shown below. Figure 1 ,

[0041] The integrated half-bridge switching resonant unit includes a DC power supply V in Switch S1, Switch S2, Resonant capacitor C r1 Resonant capacitor C r2 Common inductor L s The output of the integrated half-bridge switching resonant unit includes two independent full-wave rectifier dual-path current sharing units, with a DC input power supply V. in The positive terminals are connected to the drain of the switching transistor S1 and the resonant capacitor C, respectively. r1 The positive terminal, resonant capacitor C r1 The negative terminal is connected to the positive terminal of the first full-wave rectifier dual-path current sharing unit. The source of switch S1 and the drain of switch S2 are both connected to the common inductor L. s The positive terminal is connected, and the common inductor L s The negative terminals of the transistors are connected to the negative terminals of the first full-wave rectifier dual-path current sharing unit and the positive terminals of the second full-wave rectifier dual-path current sharing unit, respectively. The source terminal of the switching transistor S2 is connected to the DC input power supply V. in The negative terminal and resonant capacitor C r2 The negative terminal is connected, and the resonant capacitor C r2 The positive terminal is connected to the negative terminal interface of the two full-wave rectifier dual-path current sharing units.

[0042] The first full-wave rectifier dual-path current sharing unit includes freewheeling diodes D1, D2, D3, and D4, and a filter capacitor value C. o1 Filter capacitor value C o2 Output load LED1 and output load LED2.

[0043] The positive terminal of the first full-wave rectifier dual-path current sharing unit is connected to the cathode of freewheeling diode D1 and the anode of freewheeling diode D2, respectively. The cathode of freewheeling diode D2 is connected to the anode of output load LED1. The cathodes of output load LED1, D4, and LED2 are all connected to the anode of freewheeling diode D1. The anode of output load LED2 is connected to the cathode of freewheeling diode D3. The anodes of freewheeling diode D3 and D4 are both connected to the negative terminal of the first full-wave rectifier dual-path current sharing unit. A filter capacitor with a value of C is connected in parallel between the anode and cathode of output load LED1. o1 The output load LED2 has a filter capacitor with value C connected in parallel between its anode and cathode. o2 .

[0044] The second full-wave rectifier dual-path current sharing unit includes freewheeling diodes D5, D6, D7, and D8, and a filter capacitor with a value of C. o3 Filter capacitor value C o4 Output load LED3 and output load LED4.

[0045] The negative terminal of the second full-wave rectifier dual-path current sharing unit is connected to the cathode of freewheeling diode D7 and the anode of freewheeling diode D8, respectively. The cathode of freewheeling diode D8 is connected to the anode of output load LED4. The cathodes of output load LED4, D7, and LED3 are all connected to the anode of freewheeling diode D6. The anode of output load LED3 is connected to the cathode of freewheeling diode D5. The anodes of freewheeling diode D5 and D6 are both connected to the positive terminal of the second full-wave rectifier dual-path current sharing unit. A filter capacitor with value C is connected in parallel between the anode and cathode of output load LED3. o3 The output load LED4 has a filter capacitor with value C connected in parallel between its anode and cathode. o4 .

[0046] The first full-wave rectifier dual-path current sharing unit, resonant capacitor C r1 and common inductor L s The AC equivalent output load of the first full-wave rectifier dual-path current sharing unit, forming the first resonant cavity, is R. ac1 Resonant capacitor C r1 The connection node with the drain of the switching transistor S1 and the common inductance L sThe connection node with the source of the switching transistor S1 forms the input terminal of the first resonant cavity.

[0047] The second full-wave rectifier dual-path current sharing unit, resonant capacitor C r2 and common inductor L s The AC equivalent output load of the second full-wave rectifier dual-path current sharing unit, forming the second resonant cavity, is R. ac2 Public inductor L s The connection node with the drain of the switching transistor S2 and the resonant capacitor C r2 The connection node with the source of the switching transistor S2 forms the input terminal of the second resonant cavity.

[0048] To simplify the analysis, assume...

[0049] (1) All switching transistors, diodes, capacitors and inductors are ideal devices.

[0050] (2) Filter capacitor C o1 C o2 C o3 and C o4 The capacitance value is much larger than the resonant capacitance value C. r1 and C r2 Generally, the resonant filter capacitor C o1 C o2 C o3 and C o4 The capacitance value is greater than 3.3 times the resonant capacitance C. r1 The capacitance value, the resonant capacitance C r1 The capacitance value is the resonant capacitor C. r2 It is more than 30 times the capacitance value, therefore V LED1 V LED2 V LED3 and V LED4 It is a constant value.

[0051] A soft-switching multi-channel dimmable LED driving method has six modes sequentially within one switching cycle, namely mode 1 to mode 6, as shown in Figures 2(a) to 2(f):

[0052] Mode 1 [t0,t1]: As shown in Figure 2(a), when switch S1 is turned on, mode 1 starts from t0. When switch S2 is turned off, the drain-source voltage of switch S2 is V. in At this moment, the instantaneous current i of the common inductor Ls Ls Because it withstands a positive voltage, the voltage rises linearly and freewheels through the body diode of switch S1, making the drain-source voltage of switch S1 zero, thus providing zero-voltage turn-on (ZVS condition) for switch S1. Resonant capacitor C r1 The resonant current I on cr1and resonant capacitor C r2 The resonant current I on cr2 When the resonance reaches zero, freewheeling diodes D2, D4, D6, and D8 conduct, while freewheeling diodes D1, D3, D5, and D7 achieve zero-current turn-off. When the common inductor L... s instantaneous current i Ls When the value rises to 0, mode 1 ends and mode 6 begins.

[0053] Mode 2 [t1,t2]: As shown in Figure 2(b), when i Ls =0, i Cr1 =0, i Cr2 When =0, i Ls i cr1 and i cr2 Defined as common inductance L s Resonant capacitor C r1 and resonant capacitor C r2 The instantaneous current flowing through it, mode 2 begins at time t1. The drain-source voltage of switch S2 is V. in Common inductor L s instantaneous current i Ls The linear increase, while the resonant capacitance C r2 Start charging. In this embodiment, the resonant capacitor C... r1 The capacitance value is the resonant capacitor C. r2 30 times the capacitance value, due to the resonant capacitance C r1 A larger capacitance value is required for the input power supply V. in The discharge is slow, and the current flowing through it is very small and can be ignored. At this time, only freewheeling diodes D5 and D7 are conducting, while freewheeling diodes D1, D2, D3, D4, D6, and D8 are reverse-biased and cut off. The system enters mode 3.

[0054] Mode 3 [t2,t3]: As shown in Figure 2(c), at t=t2, the common inductance L s instantaneous current i Ls Rise to peak value. Before switch S2 is turned on, the common inductance L... s instantaneous current i Ls The parasitic capacitance and resonant capacitance C of the switching transistor S1 r2 Slow charging, common inductor L s instantaneous current i Ls The parasitic capacitance and resonant capacitance C of the switching transistor S2 r1 Discharge begins. Freewheeling diodes D1, D3, D5, and D7 are turned on, while freewheeling diodes D2, D4, D6, and D8 are reverse-biased and cut off. When the drain-source voltage of switch S2 drops to zero, the body diode of switch S2 turns on, entering mode 4.

[0055] Mode 4 [t3,t4]: As shown in Figure 2(d), when switch S2 is turned on, mode 4 starts from t3. When t=t3, the common inductance L s instantaneous current i Ls The voltage decreases linearly due to the reverse voltage applied, and freewheeling occurs through the body diode of switch S2, resulting in a zero-voltage turn-on (ZVS) condition for switch S2. Resonant capacitor C r1 The resonant current I on cr1 and resonant capacitor C r2 The resonant current I on cr2 Resonance reaches zero. Freewheeling diodes D1, D3, D5, and D7 conduct, while freewheeling diodes D2, D4, D6, and D8 achieve zero-current turn-off. Entering mode 5.

[0056] Mode 5 [t4,t5]: As shown in Figure 2(e), when the common inductance L s instantaneous current i Ls =0, i Cr1 =0, i Cr2 When t=0, mode 5 begins at time t4. The drain-source voltage of switch S1 is V. in Common inductor L s instantaneous current i Ls It becomes negative after time t3 and decreases linearly. The resonant capacitance C r2 For common inductor L s Charging, input power V in For resonant capacitor C r1 Slow charging occurs because the current flowing through it is small and negligible. Freewheeling diodes D6 and D8 are conducting, while freewheeling diodes D1, D2, D3, D4, D5, and D7 are reverse-biased and cut off. When the common inductor L... s instantaneous current i Ls When the temperature drops to 0, mode 5 ends and mode 6 begins.

[0057] Mode 6 [t5,t6]: As shown in Figure 2(f), before t=t6, that is, before the switching transistor S1 is turned on, the common inductance L s instantaneous current i Ls It continues to decrease linearly until it reaches its peak. Common inductance L s instantaneous current iL s The parasitic capacitance and resonant capacitance C of the switching transistor S2 r1 Charging, common inductor L s instantaneous current iL s For the parasitic capacitance of switching transistor S1, the common inductance L s instantaneous current iL s For resonant capacitor C r2Discharge. Freewheeling diodes D2, D4, D6, and D8 conduct, while freewheeling diodes D1, D3, D5, and D7 are reverse-biased and cut off. When the drain-source voltage of switching transistor S1 drops to zero, the body diode of switching transistor S1 turns on, and the next switching cycle begins.

[0058] Modal analysis shows that in modes 1 and 6, due to the unidirectional conductivity of the diode, the energy storage capacitor C... r1 The energy storage capacitor C is charged through the load LED1 and freewheeling diodes D2 and D4 within one switching cycle. r1 The amount of charge ΔQ1ch during charging is equal to the amount of charge flowing through the output load LED1 in one switching cycle; similarly, in modes 3 and 4, the energy storage capacitor C... r1 The energy storage capacitor C is charged within one switching cycle by the load LED2 and freewheeling diodes D1 and D3. r1 The amount of charge discharged, ΔQ1dis, is equal to the amount of charge flowing through the output load LED2 in one switching cycle. Since the filter capacitor is large enough, the output current can be considered a constant value. Therefore, the following relationship holds:

[0059] (1)

[0060] Modal analysis shows that in modes 1 and 6, due to the unidirectional conductivity of the diode, the energy storage capacitor C... r2 Discharge is achieved through load LED4 and freewheeling diodes D6 and D8. Within one switching cycle, the energy storage capacitor C... r2 The amount of charge discharged, ΔQ2dis, is equal to the amount of charge flowing through the output load LED4 within one switching cycle; similarly, in modes 3 and 4, the energy storage capacitor C... r2 The energy storage capacitor C is charged through the load LED3 and freewheeling diodes D5 and D7 within one switching cycle. r2 The amount of charge ΔQ2ch during charging is equal to the amount of charge flowing through the output load LED3 in one switching cycle. Since the filter capacitor is large enough, the output current can be considered a constant value, and the following relationship holds: Similarly, from the modal analysis of modes 1 and 6 and modes 3 and 4, we can obtain:

[0061] (2)

[0062] According to the principle of capacitor charge balance, the relationship between the capacitor charge / discharge balance and the amount of charge flowing through the capacitor in each mode during one switching cycle is shown in the following equation:

[0063] (3)

[0064] (4)

[0065] From (1) to (4), we can obtain:

[0066] (5)

[0067] Therefore, this circuit topology can utilize the charge balance principle of the resonant capacitor to achieve current sharing between the upper and lower paths of the four output currents.

[0068] Figure 3 This is a simplified AC equivalent circuit diagram of the dual resonant cavity of the present invention, wherein the two resonant slots share a common inductor L. s When pulse frequency modulation (PFM) is used, the duty cycles of Q1 and Q2 are complementary. According to Fourier series analysis, the equivalent input voltage of each phase is:

[0069] (6)

[0070] Where point A is the drain of switch S1, point B is the source of switch S1 (and the drain of switch S2), and point C is the source of switch S2, V AB Let V be the voltage between points A and B. BC Let t be the voltage between points B and C, and t be the time.

[0071] Since the two resonant capacitors have different capacitance values, the resonant frequencies of the two resonant cavities are:

[0072] (7)

[0073] The AC equivalent circuit of the first resonant cavity has the following voltage gain:

[0074] (8)

[0075] The inductance of the first resonant cavity is: The capacitance reactance is AC equivalent resistance ,in ;

[0076] From (6) and (8), the static gain G1 of the first resonant cavity can be obtained as follows:

[0077] (9)

[0078] Similarly, the static gain of the second resonant cavity is:

[0079] (10)

[0080] The inductance of the second resonant cavity is: The capacitance reactance is AC equivalent resistance ,in ;

[0081] Analysis revealed that the instantaneous value i of the resonant inductor current flowing through the first resonant cavity at any given moment in this invention... Ls1 (t) is: (11)

[0082] in, (12)

[0083] Similarly, the instantaneous value of the resonant inductor current flowing through the second resonant cavity at any given moment is: (13)

[0084] in, (14)

[0085] Using equations (11) and (13), the peak value Im of the common resonant inductance Ls of this invention can be obtained as follows: (15)

[0086] Since the current is filtered by the rectifier diode and the output capacitor, the output current can be obtained through analysis: (16)

[0087] A PSIM simulation was built based on the soft-switching multi-channel dimmable LED driver shown in Figures 2(a) to 2(f), and the main simulation waveforms are shown in Figures 4(a) to 4(f). The main simulation parameters are set as follows: power input voltage V in The voltage is 48V, and the resonant capacitor C is... r1 =3uF, resonant capacitor C r2 =100nF, common inductance L s =10uH, switching frequency is 180kHz, duty cycle D=0.2, rated output load equivalent impedance R LED1 R LED2 R LED3 R LED4 The filter capacitor C is 35Ω. o1 C o2 C o3 C o4 It is 10uF.

[0088] Table 1: Output Current I LED1 / 2 I LED3 / 4 (Unit: mA) Table showing the relationship between switching frequency and duty cycle in the range of 130kHz~200kHz.

[0089]

[0090] Since the two switching transistors conduct in a complementary manner, the four-channel output current of the LED is the largest when D=0.5; the four-channel output current when D=0.2 is equal to the four-channel output current when D=0.8, the four-channel output current when D=0.3 is equal to the four-channel output current when D=0.7, and so on. Therefore, this table only records the data when D=0.2~0.5.

[0091] This invention can achieve zero-voltage turn-on of switching transistors S1 and S2 and zero-current turn-off of diodes within the switching frequency range of 130kHz to 200kHz and the duty cycle range of 0.2 to 0.8.

[0092] To verify the current sharing effect of the output load of each resonator under extreme imbalance conditions, the equivalent impedance R of the output load was set. LED1 R LED2 R LED3 R LED4 The current ratings are 20Ω, 50Ω, 30Ω, and 40Ω. The output current waveform is shown in Figure 4(g).

[0093] Based on the above analysis, the soft-switching multi-channel dimmable LED driver proposed in this invention can achieve four-channel current output, wherein the output load current is 1 / 2 I. LED1 / 2 Current sharing, output load current I 3 / 4 LED3 / 4 Current sharing, output load 1 / 2 current I LED1 / 2 and output load 3 / 4 current I LED3 / 4 Both channels are dimmable within a certain current range. Furthermore, it enables zero-voltage turn-on of the switching transistor and zero-current turn-off of the diode.

[0094] The above-disclosed embodiments are merely the simplest implementations of the present invention, but the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the scope of the claims and any improvements made without departing from the principle of the present invention.

Claims

1. A soft-switching multi-channel dimmable LED driver, comprising a DC power supply V in Its characteristics are, It also includes switching transistor S1, switching transistor S2, and resonant capacitor C. r1 Resonant capacitor C r2 Common inductor L s The first full-wave rectifier dual-path current sharing unit and the second full-wave rectifier dual-path current sharing unit, DC input power supply V in The positive terminals are connected to the drain of the switching transistor S1 and the resonant capacitor C, respectively. r1 The positive terminal, resonant capacitor C r1 The negative terminal is connected to the positive terminal of the first full-wave rectifier dual-path current sharing unit. The source of switch S1 and the drain of switch S2 are both connected to the common inductor L. s The positive terminal is connected, and the common inductor L s The negative terminals of the transistors are connected to the negative terminals of the first full-wave rectifier dual-path current sharing unit and the positive terminals of the second full-wave rectifier dual-path current sharing unit, respectively. The source terminal of the switching transistor S2 is connected to the DC input power supply V. in The negative terminal and resonant capacitor C r2 The negative terminal is connected, and the resonant capacitor C r2 The positive terminal is connected to the negative terminal interface of the second full-wave rectifier dual-path current sharing unit.

2. The soft-switching multi-channel dimmable LED driver according to claim 1, characterized in that, The first full-wave rectifier dual-path current sharing unit includes freewheeling diodes D1, D2, D3, and D4, and a filter capacitor value C. o1 Filter capacitor value C o2 Output load LED1 and output load LED2, The positive terminal of the first full-wave rectifier dual-path current sharing unit is connected to the cathode of freewheeling diode D1 and the anode of freewheeling diode D2, respectively. The cathode of freewheeling diode D2 is connected to the anode of output load LED1. The cathodes of output load LED1, D4, and LED2 are all connected to the anode of freewheeling diode D1. The anode of output load LED2 is connected to the cathode of freewheeling diode D3. The anodes of freewheeling diode D3 and D4 are both connected to the negative terminal of the first full-wave rectifier dual-path current sharing unit. A filter capacitor with a value of C is connected in parallel between the anode and cathode of output load LED1. o1 The output load LED2 has a filter capacitor with value C connected in parallel between its anode and cathode. o2 .

3. The soft-switching multi-channel dimmable LED driver according to claim 2, characterized in that, The second full-wave rectifier dual-path current sharing unit includes freewheeling diodes D5, D6, D7, and D8, and a filter capacitor value C. o3 Filter capacitor value C o4 Output load LED3 and output load LED4 The negative terminal of the second full-wave rectifier dual-path current sharing unit is connected to the cathode of freewheeling diode D7 and the anode of freewheeling diode D8, respectively. The cathode of freewheeling diode D8 is connected to the anode of output load LED4. The cathodes of output load LED4, D7, and LED3 are all connected to the anode of freewheeling diode D6. The anode of output load LED3 is connected to the cathode of freewheeling diode D5. The anodes of freewheeling diode D5 and D6 are both connected to the positive terminal of the second full-wave rectifier dual-path current sharing unit. A filter capacitor with value C is connected in parallel between the anode and cathode of output load LED3. o3 The output load LED4 has a filter capacitor with value C connected in parallel between its anode and cathode. o4 .

4. A soft-switching multi-channel dimmable LED driving method, utilizing the soft-switching multi-channel dimmable LED driver described in claim 3, characterized in that... One switching cycle includes the following modes: Mode 1 begins and ends at times t0 and t1, respectively. When switch S1 is turned on, Mode 1 begins at time t0. Switch S2 is turned off, and the drain-source voltage of switch S2 is equal to the input power supply voltage V. in The instantaneous current i of the common inductor Ls Ls The voltage rises linearly under forward bias and freewheels through the body diode of switch S1, making the drain-source voltage of switch S1 zero, thus providing zero-voltage turn-on for switch S1. The resonant capacitor C... r1 The resonant current I on cr1 and resonant capacitor C r2 The resonant current I on cr2 When the resonance reaches zero, freewheeling diodes D2, D4, D6, and D8 conduct, while freewheeling diodes D1, D3, D5, and D7 achieve zero-current turn-off. When the common inductor L... s instantaneous current i Ls When it rises to 0, it enters mode 2.

5. The soft-switching multi-channel dimmable LED driving method according to claim 4, characterized in that, It also includes the following modes: Mode 2, with start and end times t1 and t2, i Ls i cr1 and i cr2 Defined as common inductance L s Resonant capacitor C r1 and resonant capacitor C r2 The instantaneous current flowing through i Ls =0, i Cr1 =0, i Cr2 When = 0, mode 2 starts at time t1, and the drain-source voltage of switch S2 is equal to the input power supply V. in Public inductor L s instantaneous current i Ls The linear increase, while the resonant capacitance C r2 Charging begins, resonant capacitor C r1 For input power supply V in Slow discharge occurs, freewheeling diodes D5 and D7 are turned on, while freewheeling diodes D1, D2, D3, D4, D6, and D8 are reverse-biased and cut off, entering mode 3.

6. The soft-switching multi-channel dimmable LED driving method according to claim 5, characterized in that, It also includes the following modes: Mode 3, with start and end times t2 and t3, respectively. At time t2, the common inductance L... s instantaneous current i Ls Before the switching transistor S2 turns on when the peak value is reached, the common inductance L s instantaneous current i Ls The parasitic capacitance and resonant capacitance C of the switching transistor S1 r2 Slow charging, common inductor L s instantaneous current i Ls The parasitic capacitance and resonant capacitance C of the switching transistor S2 r1 Discharge begins, freewheeling diodes D1, D3, D5, and D7 conduct, while freewheeling diodes D2, D4, D6, and D8 are reverse-biased and cut off. When the drain-source voltage of switch S2 drops to zero, the body diode of switch S2 turns on, entering mode 4.

7. The soft-switching multi-channel dimmable LED driving method according to claim 6, characterized in that, It also includes the following modes: Mode 4 begins and ends at times t3 and t4. When switch S2 is turned on, mode 4 starts at time t3, and the common inductance L... s instantaneous current i Ls The voltage decreases linearly under reverse voltage and freewheels through the body diode of switch S2, making the drain-source voltage of switch S2 zero, thus providing zero-voltage turn-on for switch S2. The resonant capacitor C... r1 The resonant current I on cr1 and resonant capacitor C r2 The resonant current I on cr2 When the resonance reaches zero, freewheeling diodes D1, D3, D5, and D7 conduct, while freewheeling diodes D2, D4, D6, and D8 achieve zero-current turn-off, entering mode 5.

8. The soft-switching multi-channel dimmable LED driving method according to claim 7, characterized in that, It also includes the following modes: Mode 5, with start and end times t4 and t5, when the common inductance L... s instantaneous current i Ls =0, i Cr1 =0, i Cr2 When = 0, mode 5 starts at time t4, and the drain-source voltage of switch S1 is equal to the input power supply V. in Public inductor L s instantaneous current i Ls After time t3, it becomes negative and decreases linearly, indicating the resonant capacitance C. r2 For common inductor L s Charging, input power V in For resonant capacitor C r1 During slow charging, freewheeling diodes D6 and D8 are turned on, while freewheeling diodes D1, D2, D3, D4, D5, and D7 are reverse-biased and cut off. When the common inductor L... s instantaneous current i Ls When the value drops to 0, mode 5 ends.

9. The soft-switching multi-channel dimmable LED driving method according to claim 8, characterized in that, It also includes the following modes: Mode 6 begins and ends at times t5 and t6. At time t6, before switch S1 is turned on, the common inductance L... s instantaneous current i Ls The inductance continues to decrease linearly until it reaches its peak value, with the common inductance L... s instantaneous current iL s The parasitic capacitance and resonant capacitance C of the switching transistor S2 r1 Charging, common inductor L s instantaneous current iL s For the parasitic capacitance of switching transistor S1, the common inductance L s instantaneous current iL s For the resonant capacitor C r2 Discharge occurs, freewheeling diodes D2, D4, D6, and D8 conduct, while freewheeling diodes D1, D3, D5, and D7 are reverse-biased and cut off. When the drain-source voltage of switching transistor S1 drops to zero, the body diode of switching transistor S1 turns on, and the next switching cycle begins.

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