LED driver and method of operating the same

Abstract

The invention provides an LED driver and an operation method thereof. The LED driver comprises a plurality of conversion circuits and a control circuit. The plurality of conversion circuits are respectively used for being coupled with the plurality of LED light sources and supplying power to the plurality of LED light sources. The control circuit is used for setting the conversion circuit to generate an output current and an output voltage; calculating to obtain the output power of the conversion circuit; summing up the output power of all the conversion circuits to obtain total output power; and when the total output power is judged to be greater than the power upper limit, arranging at least one conversion circuit to adjust and reduce the output current according to the power upper limit and at least one of the total output power and the output power of the individual conversion circuit, so that the total output power is reduced to be less than or equal to the power upper limit.

Description

Technical Field

[0001] This disclosure relates to an LED (light-emitting diode) driver and its operation method, and particularly to an LED driver with total power limiting protection and its operation method. Background Technology

[0002] In LED lighting applications, LED drivers are typically used to provide appropriate voltage and current to ensure stable and efficient operation of LED light sources. An LED driver may contain multiple voltage converters to meet the power requirements of different LED light sources. Each voltage converter is connected to a preceding PFC (power factor correction) circuit to receive power factor-corrected energy. Furthermore, each voltage converter is also coupled to multiple LED light sources to power different LEDs individually.

[0003] While each voltage converter typically has overpower protection to automatically adjust or shut down when the output power exceeds a safe range, preventing damage from overload, from a system-wide perspective, the PFC circuit must supply power to the entire system. Furthermore, the heat dissipation capacity of the PFC circuit and the LED luminaire also affects the overall system's stability and performance. Since not all voltage converters operate at maximum power simultaneously, designing based solely on the sum of their maximum power outputs would result in an excessively large product with low power density, potentially failing to meet specific product specifications. Conversely, neglecting to consider the sum of the maximum power outputs of the LED drivers could lead to total output power and heat generation exceeding the system's tolerance, thus affecting the LED driver's operational stability and lifespan. Moreover, in applications such as plant lighting, LED drivers supply power to red, far-infrared, blue, and white LED light sources separately, requiring more flexible power adjustment for each LED to meet diverse lighting needs.

[0004] Therefore, inventing an LED driver and its operation method that can improve upon the aforementioned existing technologies is an urgent need. Summary of the Invention

[0005] The purpose of this disclosure is to provide an LED driver and its operation method to solve the aforementioned technical problems.

[0006] To achieve the above objectives, this disclosure provides an LED driver for driving a plurality of LED light sources based on an input voltage, and includes a plurality of conversion circuits and a control circuit. A plurality of output terminals of the plurality of conversion circuits are respectively coupled to the plurality of LED light sources to supply power to the plurality of LED light sources. The plurality of conversion circuits form a first-stage circuit and a second-stage circuit. The first-stage circuit includes an input terminal for receiving the input voltage, and the second-stage circuit includes an input terminal coupled to an output terminal in the first-stage circuit. The control circuit is coupled to the plurality of conversion circuits and is used to set each of the plurality of conversion circuits to generate an output current and an output voltage at its output terminal. The control circuit calculates the output power of each of the plurality of conversion circuits based on the output current and output voltage of each of the plurality of conversion circuits. The control circuit sums the plurality of output powers of the plurality of conversion circuits to obtain the total output power. When the control circuit determines that the total output power is greater than the power limit, the control circuit sets at least one of the plurality of conversion circuits to reduce the output current based on the power limit, the total output power and the output power of individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit.

[0007] To achieve the above objectives, this disclosure further provides a method for operating an LED driver, wherein the LED driver is used to drive a plurality of LED light sources according to an input voltage, and includes a plurality of conversion circuits and a control circuit. A plurality of output terminals of the plurality of conversion circuits are respectively coupled to the plurality of LED light sources to supply power to the plurality of LED light sources, and the plurality of conversion circuits form a first-stage circuit and a second-stage circuit. The first-stage circuit includes an input terminal for receiving the input voltage, and the second-stage circuit includes an input terminal coupled to an output terminal in the first-stage circuit. The control circuit is coupled to the plurality of conversion circuits. The operating method includes the following steps: (a) setting the control circuit to generate output current and output voltage at the output terminal of each plurality of conversion circuits; (b) setting the control circuit to calculate the output power of each plurality of conversion circuits based on the output current and output voltage of each plurality of conversion circuits; (c) setting the control circuit to sum the plurality of output powers of the plurality of conversion circuits to obtain the total output power; and (d) when it is determined that the total output power is greater than the power limit, setting the control circuit to reduce the output current of at least one of the plurality of conversion circuits based on the power limit, and based on at least one of the total output power and the output power of individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit.

[0008] This invention reduces the output current of each conversion circuit when the total output power is too high, thereby limiting the total output power to within the acceptable range of the overall system, thereby improving the operational stability and lifespan of the LED driver. Attached Figure Description

[0009] Figure 1This is a schematic diagram of the architecture of an LED driver according to an embodiment of the present disclosure.

[0010] Figure 2 for Figure 1 A schematic diagram of the control circuit architecture.

[0011] Figure 3 This is a flowchart illustrating the operation method of an LED driver according to an embodiment of the present disclosure.

[0012] Explanation of reference numerals in the attached figures:

[0013] 1: LED driver

[0014] 11: First conversion circuit

[0015] 12: Second conversion circuit

[0016] 13: Third conversion circuit

[0017] 14: Fourth conversion circuit

[0018] 15: Fifth conversion circuit

[0019] 21, 22, 23, 24, 25: LED light source

[0020] 3: Control circuit

[0021] 4: PFC circuit

[0022] Vac: AC voltage

[0023] Vdc: DC voltage

[0024] V1, V2, V3, V4, V5: Output voltage

[0025] I1: Output current

[0026] 31: Current setting unit

[0027] 32: Sampling unit

[0028] 33: Computational Unit

[0029] 34: Judgment Unit

[0030] 35: Control Interface

[0031] S11, S12, S13, S14, S15, S16, S17, S18: Steps Detailed Implementation

[0032] Some typical embodiments embodying the features and advantages of this disclosure will be described in detail in the following description. It should be understood that this disclosure can be varied in different implementations without departing from the scope of this disclosure, and the descriptions and illustrations therein are for illustrative purposes only and not for limiting the scope of this disclosure.

[0033] Figure 1 This is a schematic diagram of the architecture of an LED driver according to an embodiment of this disclosure. Figure 1 As shown, LED driver 1 is used to drive a plurality of LED light sources (five LED light sources 21, 22, 23, 24, and 25 are used as an example in the figure). Figure 1 In this embodiment, the LED driver 1 includes a PFC circuit 4, a control circuit 3, and a first-stage circuit and a second-stage circuit formed by a plurality of conversion circuits. The first-stage circuit includes one or more conversion circuits (two conversion circuits are used as an example in the figure, namely the first conversion circuit 11 and the second conversion circuit 12), and the second-stage circuit includes one or more conversion circuits (three conversion circuits are used as an example in the figure, namely the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15). For the sake of simplicity and ease of explanation, Figure 1 Other components of the LED driver 1 are not shown in the diagram. In this embodiment, the LED driver 1 is divided into a PFC circuit 4, a first conversion circuit 11, a second conversion circuit 12, a third conversion circuit 13, a fourth conversion circuit 14, a fifth conversion circuit 15, and a control circuit 3 to clearly illustrate the operation of the LED driver 1. The PFC circuit 4, first conversion circuit 11, second conversion circuit 12, third conversion circuit 13, fourth conversion circuit 14, fifth conversion circuit 15, and control circuit 3 can be implemented using suitable circuit elements, or they can be integrated or implemented separately as one or more circuit elements. In another embodiment, the PFC circuit 4, first conversion circuit 11, second conversion circuit 12, third conversion circuit 13, fourth conversion circuit 14, fifth conversion circuit 15, and control circuit 3 can also perform the functions of the aforementioned components within the same circuit composed of discrete components and / or integrated circuit components.

[0034] PFC circuit 4 is used to receive AC voltage Vac and generate DC voltage Vdc accordingly. PFC circuit 4 can adopt a suitable power conversion architecture to achieve power factor correction and provide the required DC voltage Vdc, such as, but not limited to, passive PFC circuit, active boost PFC circuit or bridgeless PFC circuit.

[0035] In the first-stage circuit, the input terminals of the first conversion circuit 11 and the second conversion circuit 12 are connected in parallel and both are connected to the PFC circuit 4 to receive the DC voltage Vdc. Furthermore, the output terminal of each conversion circuit in the first-stage circuit is coupled to the corresponding LED light source and supplies it with power. Specifically, in this embodiment, the output terminal of the first conversion circuit 11 is coupled to the LED light source 21, and the first conversion circuit 11 generates an output voltage V1 based on the DC voltage Vdc to supply power to the LED light source 21. The output terminal of the second conversion circuit 12 is coupled to the LED light source 22, and the second conversion circuit 12 generates an output voltage V2 based on the DC voltage Vdc to supply power to the LED light source 22. The first conversion circuit 11 and the second conversion circuit 12 can employ suitable power conversion architectures to provide the electrical energy required by the LED light sources 21 and 22, such as buck converting circuits, inverse buck converting circuits, and buck-boost converting circuits. Furthermore, depending on the circuit architecture adopted, such as buck converter circuit or inverted buck converter circuit, the positive or negative output terminals of each conversion circuit can be coupled to each other accordingly.

[0036] The input terminal of each conversion circuit in the second-stage circuit is coupled to the output terminal of the corresponding conversion circuit in the first-stage circuit to receive electrical energy, and the output terminal of each conversion circuit in the second-stage circuit is coupled to the corresponding LED light source and supplies it with power. The multiple conversion circuits in the second-stage circuit can be coupled to the same conversion circuit in the first-stage circuit, or they can be coupled to multiple different conversion circuits in the first-stage circuit. In this embodiment, the input terminals of the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 are all coupled to the output terminal of the first conversion circuit 11 to receive the output voltage V1 of the first conversion circuit 11. The output terminal of the third conversion circuit 13 is coupled to the LED light source 23, and the third conversion circuit 13 generates an output voltage V3 based on the output voltage V1 to supply power to the LED light source 23. The output terminal of the fourth conversion circuit 14 is coupled to the LED light source 24, and the fourth conversion circuit 14 generates an output voltage V4 based on the output voltage V1 to supply power to the LED light source 24. The output of the fifth conversion circuit 15 is coupled to the LED light source 25, and the fifth conversion circuit 15 generates an output voltage V5 based on the output voltage V1 to power the LED light source 25. The third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 can adopt suitable power conversion architectures to provide the power required by the LED light sources 23, 24, and 25, such as buck converter circuits, inverted buck converter circuits, and buck-boost converter circuits. In addition, depending on whether a buck converter circuit or an inverted buck converter circuit is adopted, the positive or negative output terminals of each conversion circuit can be coupled to each other accordingly.

[0037] In this embodiment, the DC voltage Vdc is greater than the output voltage V1 of the first-stage circuit, and the output voltage V1 is greater than the output voltages V3, V4, and V5 of the second-stage circuit. The first conversion circuit 11 in the first-stage circuit steps down the DC voltage Vdc to a lower output voltage V1, and then provides this output voltage V1 to the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 in the second-stage circuit. These circuits then convert the output voltage V1 to even lower output voltages V3, V4, and V5, respectively. The output voltages V3, V4, and V5 can be set to the same or different voltages. This embodiment, through multi-stage step-down conversion, enables the conversion circuits in both the first-stage and second-stage circuits to operate within a high conversion efficiency range. In another embodiment, the first conversion circuit 11 and the second conversion circuit 12 of the first stage circuit can be configured to provide the output voltages V1 and V2 to the third conversion circuit 13, the fourth conversion circuit 14 and the fifth conversion circuit 15 in the second stage circuit, respectively, so that the third conversion circuit 13, the fourth conversion circuit 14 and the fifth conversion circuit 15 can convert the output voltages V1 and V2 into lower output voltages V3, V4 and V5, respectively.

[0038] Control circuit 3 is coupled to the first-stage circuit and the second-stage circuit; in this embodiment, it is coupled to the first conversion circuit 11, the second conversion circuit 12, the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15. Control circuit 3 may include logic circuits and other components to control the operation of each conversion circuit. For example, Figure 2 for Figure 1 A schematic diagram of an embodiment of the control circuit 3 is shown, wherein the control circuit 3 includes a current setting unit 31, a sampling unit 32, an arithmetic unit 33, a judgment unit 34, and a control interface 35. For the sake of simplicity and ease of explanation, Figure 2 In this embodiment, other components of the control circuit 3 are not shown. In other embodiments, the components of the control circuit 3 may be added or removed depending on different design considerations. In this embodiment, the control circuit 3 is divided into a current setting unit 31, a sampling unit 32, an arithmetic unit 33, a judgment unit 34, and a control interface 35 to clearly illustrate the control method of the control circuit 3 for the operation of each conversion circuit. These components can be implemented using appropriate circuit elements, or integrated, or implemented separately using one or more circuit elements. In another embodiment, the current setting unit 31, sampling unit 32, arithmetic unit 33, judgment unit 34, and control interface 35 may also perform the functions of the aforementioned components using the same circuit composed of discrete components and / or integrated circuit components, or implemented using software and / or firmware combined with hardware.

[0039] Please see Figure 1 and Figure 2 The current setting unit 31 of the control circuit 3 can set the required output current for each conversion circuit. In some embodiments, the control circuit 3 can receive a command (e.g., parameters such as the on / off state or brightness of each LED light source input by the user) through the control interface 35, so that the current setting unit 31 sets the required output current for each conversion circuit according to the command. For example, the control interface 35 can be implemented in a suitable manner, such as a graphical user interface or a digital addressable lighting interface (DALI).

[0040] The sampling unit 32 of the control circuit 3 can sample the output voltage and / or output current generated by the conversion circuit. Since the output current generated by the conversion circuit is set by the current setting unit 31, the calculation unit 33 of the control circuit 3 can calculate the output power of the conversion circuit based on the sampled output current and sampled output voltage, or it can calculate the output power of the conversion circuit based on its set output current and sampled output voltage. For example, the current setting unit 31 sets the first conversion circuit 11 to generate an output current I1 at its output terminal, the sampling unit 32 samples the output voltage V1 at the output terminal of the first conversion circuit 11, and the calculation unit 33 multiplies the set output current I1 of the first conversion circuit 11 and the sampled output voltage V1 to calculate the output power of the first conversion circuit 11. In another embodiment, the sampling unit 32 samples the output voltage V1 and output current I1 at the output terminal of the first conversion circuit 11, and the calculation unit 33 multiplies the sampled output current I1 and sampled output voltage V1 of the first conversion circuit 11 to calculate the output power of the first conversion circuit 11. Similarly, control circuit 3 can obtain the output power of the second conversion circuit 12, the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 in the same way. The arithmetic unit 33 sums the output power of the conversion circuits to obtain the total output power of the LED driver 1 (the arithmetic unit 33 can sum the output power of all conversion circuits, or it can sum only the output power of the conversion circuits in operation). The judgment unit 34 compares the total output power with the power limit, where the power limit can be set to be less than the sum of the rated power of all conversion circuits, less than the sum of the overpower protection trigger power of all conversion circuits, or other suitable values ​​(the specific value of the power limit can be set according to actual needs, for example, based on the load capacity of the PFC circuit 4 and the heat dissipation capacity of the LED light source). When the judgment unit 34 determines that the total output power is greater than the power limit, control circuit 3 executes the adjustment mode. In the adjustment mode, the current setting unit 31 of the control circuit 3 sets the output current of each conversion circuit to adjust the output power of each conversion circuit based on the power upper limit, and at least one of the total output power and the output power of each individual conversion circuit (e.g., at least one of the six factors: the output power of the five conversion circuits (11-15) and their summed total output power), thereby adjusting the output power of each conversion circuit and reducing the total output power to less than or equal to the power upper limit. In some embodiments, the current setting unit 31 of the control circuit 3 determines the adjustment ratio based on the difference between the total output power and the power upper limit, and sets each conversion circuit to adjust its output current by the same or different adjustment ratios. For example, the control circuit 3 sets each conversion circuit to reduce its output current using the same adjustment ratio based on the difference between the total output power and the power upper limit.For example, when the total output power is 2000W and the power limit is 1800W, the control circuit 3, based on the difference between the total output power and the power limit being 200W, correspondingly sets each conversion circuit to reduce its output current by 200W / 2000W = 10% or a larger percentage, so that the total output power decreases to less than or equal to the power limit. In another embodiment, when the total output power is 2000W and the power limit is 1800W, the control circuit 3 can also, based on the difference between the total output power and the power limit, set the output current reduction ratio for each conversion circuit separately, so that the total output power of the LED driver 1 decreases to 1800W or a lower power value. For example, the control circuit 3, based on the total output power and the output power of individual conversion circuits, reduces the output current of conversion circuits with higher output power by a larger percentage and reduces the output current of conversion circuits with lower output power by a smaller percentage. In another embodiment, the control circuit 3 reduces the output current of the conversion circuit 11 with a larger output power by a smaller proportion, and reduces the output current of the conversion circuit with a smaller output power by a larger proportion, based on the total output power and the output power of the individual conversion circuits.

[0041] Therefore, the LED driver 1 disclosed herein can limit the total output power to within the acceptable range of the overall system, thereby achieving the total power limiting protection function and improving the operational stability and lifespan of the LED driver.

[0042] At Figure 1 In the illustrated embodiment, the multiple conversion circuits of the LED driver 1 form a two-stage circuit. In another embodiment, the multiple conversion circuits of the LED driver can also form a more advanced circuit, wherein, except for the conversion circuit in the first stage, the input terminal of the conversion circuit in any stage is coupled to the output terminal of the corresponding conversion circuit in the previous stage. Furthermore, in yet another embodiment, the multiple conversion circuits of the LED driver can also form a single-stage circuit, meaning that the input terminals of all conversion circuits are connected in parallel and receive the same input voltage. By configuring the LED driver 1 with a suitable circuit architecture to enable the conversion circuits to operate in the desired operating mode, technical effects such as improved conversion efficiency are achieved.

[0043] Furthermore, the components of LED driver 1 can be added or removed depending on different design considerations. For example, in Figure 1 In the illustrated embodiment, the LED driver 1 includes a PFC circuit 4. In another embodiment, when the LED driver is coupled to a DC input power supply, the LED driver may not include a PFC circuit 4.

[0044] The control circuit 3 can transmit control signals in pulse width modulation (PWM), pulse frequency modulation (PFM), or other suitable formats to set the output current of each conversion circuit. In one embodiment, the control circuit 3 provides PWM format control signals to each conversion circuit to generate the required output current accordingly. The control circuit 3 sets a set current for the first conversion circuit 11 and provides PWM format control signals to the first conversion circuit 11 according to the set current. By setting the duty cycle of the control signals, the first conversion circuit 11 operates according to the control signals and generates an output current equal to the set current. Similarly, the control circuit 3 can provide PWM format control signals to the second conversion circuit 12, the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 respectively, so that the second conversion circuit 12, the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 generate output currents equal to the corresponding set currents.

[0045] In some embodiments, the duty cycle of the PWM format control signal provided by the control circuit 3 is positively correlated with the output current of the corresponding conversion circuit. Therefore, in the adjustment mode, the control circuit 3 can reduce the output current of the corresponding conversion circuit by decreasing the duty cycle of the PWM format control signal.

[0046] Please see Figure 3 and pair Figure 1 ,in Figure 3 This is a flowchart illustrating an operation method of an LED driver according to an embodiment of the present disclosure. This operation method is applicable to... Figure 1 The LED driver 1 is shown. Taking the LED driver 1 as an example, where multiple conversion circuits form a first conversion circuit group and a second conversion circuit group, the first conversion circuit group includes a first conversion circuit 11, a second conversion circuit 12, and a third conversion circuit 13 with higher power, and the second conversion circuit group includes a fourth conversion circuit 14 and a fifth conversion circuit 15 with lower power. Figure 1 and Figure 3 As shown, in step S11, the control circuit 3 controls the first conversion circuit group to start. In step S12, the control circuit 3 obtains the total output power of the LED driver 1 (which is the sum of the output power of the first conversion circuit group at this time). In step S13, the control circuit 3 determines whether the total output power of the LED driver 1 (which is the sum of the output power of the operating conversion circuits of the first conversion circuit group at this time) is greater than the power upper limit.

[0047] If the judgment result of step S13 is yes (i.e., the total output power of LED driver 1 is greater than the power limit), then in step S14, control circuit 3 executes adjustment mode. In adjustment mode, since the second conversion circuit group has not yet been started, control circuit 3 sets the conversion circuit in the first conversion circuit group to reduce the output current according to at least one of the power limit, the total output power, and the output power of the individual conversion circuits, so as to reduce the total output power of LED driver 1 to less than or equal to the power limit.

[0048] After executing step S14, step S13 will be executed again to determine whether the total output power of LED driver 1 is greater than the power limit. If the result of step S13 is negative (i.e., the total output power of LED driver 1 is less than or equal to the power limit), then step S15 will be executed to enable control circuit 3 to start the second conversion circuit group.

[0049] In another embodiment, the LED driver is set such that the maximum output power of the first conversion circuit group is less than the power limit. In this case, steps S13 and S14 can also be omitted. After the first conversion circuit group is started in step S11, step S15 is performed to start the second conversion circuit group.

[0050] In step S16, the control circuit 3 obtains the total output power of the LED driver 1 (which is the sum of the output power of the first conversion circuit group and the second conversion circuit group). In step S17, the control circuit 3 determines whether the total output power is greater than the power limit. If the determination result of step S17 is yes, then step S18 is executed to make the control circuit 3 execute the adjustment mode to reduce the total output power by reducing the output current of the conversion circuit. After executing step S18, step S16 will be executed again. Alternatively, if the determination result of step S17 is no, step S16 will be executed again. In subsequent operation, the control circuit 3 can continuously execute steps S16-S18, detect the total output power of the LED driver 1 and adjust the output current of the conversion circuit accordingly to ensure that the total output power of the LED driver 1 is less than or equal to the power limit.

[0051] In the adjustment modes of steps S14 and S18, the control circuit 3 can also, based on the power limit, and at least one of the total output power and the output power of individual conversion circuits, set only some conversion circuits to reduce their output current, and set specific conversion circuits to maintain or increase their output current. For example, in the adjustment mode of step S18, when the total output power of the LED driver 1 is close to the power limit and it is desired to increase the output power of the fourth conversion circuit 14, the control circuit 3 can gradually increase the output current of the fourth conversion circuit 14 and execute steps S16-S18 to correspondingly set other operating conversion circuits to reduce their output current accordingly, so as to ensure that the total output power of the LED driver 1 is less than or equal to the power limit.

[0052] exist Figure 3 In this embodiment, each conversion circuit group can be started in batches. Upon startup of each group, it is confirmed that the total output power of the already started circuits exceeds the power limit. The next batch of conversion circuit groups is only started when the total output power is confirmed to be less than or equal to the power limit. This prevents components from being damaged or failing due to high current or voltage stress during startup and provides total power limiting protection during startup. Furthermore, after all conversion circuits in all groups have been started, the total output power is continuously monitored to ensure it does not exceed the power limit. If the total output power exceeds the power limit, the output current of each conversion circuit is reduced in real time to decrease the total output power, thus continuously providing total power limiting protection during operation.

[0053] Furthermore, the classification logic for grouping multiple conversion circuits into different conversion circuit groups is unrestricted and can be determined according to actual needs. For example, in some embodiments, each conversion circuit group is formed by conversion circuits in the same level of circuitry. The first conversion circuit group includes the first conversion circuit 11 and the second conversion circuit 12 in the first level of circuitry, and the second conversion circuit group includes the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 in the second level of circuitry. In other embodiments, the sum of the rated power of the conversion circuits in each conversion circuit group is less than or equal to the upper power limit. Assuming the upper power limit is 1800W and the rated power of the first conversion circuit 11, the second conversion circuit 12, the third conversion circuit 13, the fourth conversion circuit 14, and the fifth conversion circuit 15 are 700W, 700W, 400W, 200W, and 200W, respectively, then the first conversion circuit group may include the first conversion circuit 11, the second conversion circuit 12, and the third conversion circuit 13, and the second conversion circuit group may include the fourth conversion circuit 14 and the fifth conversion circuit 15. Therefore, if the control circuit 3 only activates one of the first conversion circuit group and the second conversion circuit group, the total output power of the LED driver will not exceed the power limit.

[0054] Additionally, it should be noted that the specific number of conversion circuit groups is not limited and can be determined according to actual needs. Furthermore, when there are three or more conversion circuit groups, they can be connected to... Figure 3 The same principle applies to batch startup as shown in the diagram, so it will not be elaborated further here.

[0055] The above are merely preferred embodiments for illustrating this disclosure. This disclosure is not limited to the described embodiments, and the scope of this disclosure is determined by the scope of the patent application. Furthermore, this disclosure may be modified in various ways by those skilled in the art, but all such modifications shall not depart from the scope of protection sought in the patent application.

Claims

1. An LED driver for driving a plurality of LED light sources according to an input voltage, comprising: A plurality of conversion circuits, each having a plurality of output terminals, are respectively coupled to the plurality of LED light sources to supply power to the plurality of LED light sources. The plurality of conversion circuits form a first-stage circuit and a second-stage circuit. The first-stage circuit includes an input terminal for receiving the input voltage, and the second-stage circuit includes an input terminal coupled to an output terminal in the first-stage circuit. as well as A control circuit, coupled to the plurality of conversion circuits, is used to set each of the plurality of conversion circuits to generate an output current and an output voltage at the output terminal; The control circuit calculates the output power of each of the plurality of conversion circuits based on the output current and the output voltage of each of the plurality of conversion circuits. The control circuit sums the multiple output powers of the multiple conversion circuits to obtain a total output power; as well as When the control circuit determines that the total output power is greater than a power limit, the control circuit sets at least one of the plurality of conversion circuits to reduce the output current based on the power limit, the total output power and the output power of individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit.

2. The LED driver as claimed in claim 1, wherein the control circuit determines an adjustment ratio based on the difference between the total output power and the upper power limit, and sets each of the plurality of conversion circuits to reduce the output current by the adjustment ratio.

3. The LED driver as claimed in claim 1, wherein the control circuit determines a plurality of adjustment ratios based on the power limit, and based on at least one of the total output power and the output power of individual conversion circuits, and respectively sets each of the plurality of conversion circuits to reduce the output current based on one of the plurality of adjustment ratios.

4. The LED driver as claimed in claim 1, wherein the control circuit determines a plurality of adjustment ratios based on the power limit, and based on at least one of the total output power and the output power of individual conversion circuits, and respectively sets a portion of the plurality of conversion circuits to reduce the output current based on one of the plurality of adjustment ratios.

5. The LED driver as claimed in claim 1, wherein the plurality of conversion circuits comprises a first conversion circuit group and a second conversion circuit group; The control circuit is also used to control the startup of the first conversion circuit group and to compare the total output power with the power limit. When the control circuit determines that the total output power is greater than the power limit, it sets at least one of the plurality of conversion circuits in the first conversion circuit group to reduce the output current based on the power limit, the total output power and the output power of the individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit. After the control circuit determines that the total output power is less than or equal to the power limit, it controls the second conversion circuit group to start and compares the total output power with the power limit; and When the control circuit determines that the total output power is greater than the power limit, the control circuit sets at least one of the plurality of conversion circuits to reduce the output current based on the power limit, the total output power and the output power of the individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit.

6. A method of operating an LED driver, wherein the LED driver is used to drive a plurality of LED light sources according to an input voltage, and includes a plurality of conversion circuits and a control circuit, wherein a plurality of output terminals of the plurality of conversion circuits are respectively coupled to the plurality of LED light sources to supply power to the plurality of LED light sources, and the plurality of conversion circuits form a first-stage circuit and a second-stage circuit, the first-stage circuit including an input terminal for receiving the input voltage, the second-stage circuit including an input terminal coupled to an output terminal of the first-stage circuit, and the control circuit being coupled to the plurality of conversion circuits, the method of operating includes the steps of: (a) The control circuit is configured to generate an output current and an output voltage at the output terminal for each of the plurality of conversion circuits; (b) The control circuit is configured to calculate an output power of each of the plurality of conversion circuits based on the output current and the output voltage of each of the plurality of conversion circuits; (c) The control circuit is configured to sum the output powers of the plurality of conversion circuits to obtain a total output power; and (d) When it is determined that the total output power is greater than a power limit, the control circuit is configured to reduce the output current of at least one of the plurality of conversion circuits based on the power limit and based on at least one of the total output power and the output power of the individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit.

7. The operating method as described in claim 6, wherein, In step (d), the control circuit determines an adjustment ratio based on the difference between the total output power and the upper limit of the power, and sets each of the plurality of conversion circuits to reduce the output current by the adjustment ratio.

8. The operating method as described in claim 6, wherein, In step (d), the control circuit determines a plurality of adjustment ratios based on the power limit, and based on at least one of the total output power and the output power of the individual conversion circuits, and sets each of the plurality of conversion circuits to reduce the output current based on one of the plurality of adjustment ratios.

9. The operating method as described in claim 6, wherein, In step (d), the control circuit determines a plurality of adjustment ratios based on the power limit, and based on at least one of the total output power and the output power of the individual conversion circuits, and respectively sets some of the plurality of conversion circuits to reduce the output current based on one of the plurality of adjustment ratios.

10. The operating method of claim 6, wherein the plurality of conversion circuits comprises a first conversion circuit group and a second conversion circuit group; the operating method further comprises: The control circuit is configured to start the first conversion circuit group and compare the total output power with the power limit. When the control circuit determines that the output power of the first conversion circuit group is greater than the power limit, the control circuit sets at least one of the plurality of conversion circuits in the first conversion circuit group to reduce the output current based on the power limit, the total output power and the output power of the individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit. When the control circuit determines that the output power of the first conversion circuit group is less than or equal to the power limit, the control circuit is configured to start the second conversion circuit group, and the control circuit is configured to compare the total output power with the power limit; and When the control circuit determines that the total output power is greater than the power limit, the control circuit sets at least one of the plurality of conversion circuits to reduce the output current based on the power limit, the total output power and the output power of the individual conversion circuits, so as to reduce the total output power to less than or equal to the power limit.

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