Load driving circuit, light source device, and method of driving a load
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- O2MICRO CHINA
- Filing Date
- 2024-11-27
- Publication Date
- 2026-05-29
Smart Images
Figure CN122121007A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power electronics. More specifically, this application relates to a load driving circuit, a method for driving a load, and a light source device including the load driving circuit. Background Technology
[0002] Traditional dual-channel loads, such as LED loads, employ boost or buck topologies for their driving designs. This is particularly problematic for high-power dual-channel loads, where the driving circuits suffer from drawbacks such as high cost, low efficiency, complex design, and difficult debugging. Summary of the Invention
[0003] A brief overview of this disclosure is given below to provide a basic understanding of certain aspects of it. It should be understood that this overview is not an exhaustive summary of this disclosure. It is not intended to identify key or essential parts of this disclosure, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.
[0004] According to a first aspect of this disclosure, a load drive circuit for driving a first channel load and a second channel load is provided, comprising: a first drive branch configured to provide a first current to the first channel load and the second channel load during a positive half-cycle of an AC power supply for providing drive power to the load; and a second drive branch configured to provide a second current to the first channel load and the second channel load during a negative half-cycle of the AC power supply, wherein each of the first drive branch and the second drive branch constitutes a separate current path connecting an input terminal of the AC power supply to the first channel load and the second channel load.
[0005] According to another aspect of this disclosure, a light source device is also provided, comprising: a first LED group including one or more LED units; a second LED group including one or more LED units; and a load driving circuit according to a first aspect of this disclosure, wherein the first LED group is a first channel load and the second LED group is a second channel load.
[0006] According to other aspects of this disclosure, a method for driving a load using a load drive circuit according to a first aspect of this disclosure is also provided.
[0007] The load drive circuit and method, as well as the light source device according to embodiments of this disclosure, can reduce the number of electronic components and lower the requirements for their specifications while ensuring performance through circuit topology design and further control method design. Therefore, a more cost-effective and efficient load drive circuit and light source device are achieved.
[0008] These and other advantages of this disclosure will become more apparent from the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description
[0009] To further illustrate the above and other advantages and features of this disclosure, a more detailed description of specific embodiments of this disclosure is provided below with reference to the accompanying drawings. These drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are denoted by the same reference numerals. It should be understood that these drawings only depict typical examples of this disclosure and should not be construed as limiting the scope of this disclosure. In the drawings:
[0010] Figure 1 A schematic block diagram of a load drive circuit according to a first embodiment of the present disclosure is shown;
[0011] Figure 2 A schematic block diagram of a load drive circuit according to a second embodiment of the present disclosure is shown;
[0012] Figure 3 A circuit diagram of a load drive circuit according to a third embodiment of the present disclosure is shown;
[0013] Figure 4 A schematic diagram of the current path in the load drive circuit according to the third embodiment of the present disclosure, in which the first drive branch drives the load during the positive half-cycle of the AC power, is shown.
[0014] Figure 5 A schematic diagram of the current path in the load drive circuit according to the third embodiment of the present disclosure, in which the load is driven by the second drive branch during the negative half-cycle of the AC power, is shown.
[0015] Figure 6 This paper illustrates a load drive circuit in the prior art that powers an LED light source load.
[0016] Figure 7 A circuit diagram of a load drive circuit according to a fourth embodiment of the present disclosure is shown. Detailed Implementation
[0017] Exemplary embodiments of the present disclosure will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer’s specific goals, such as complying with constraints related to the system and business, and these constraints may vary from implementation to implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the present disclosure.
[0018] It should also be noted that, in order to avoid obscuring this disclosure with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this disclosure are shown in the accompanying drawings, while other details that are not closely related to this disclosure are omitted.
[0019] This disclosure provides a load driving circuit and method for powering a dual-channel load (e.g., a dual-channel LED), as well as a light source device including the load driving circuit. It should be understood that although LEDs are primarily used as an example of a load below, this disclosure is not limited to this type of load, but can be applied to any load with similar connection configurations and performance requirements.
[0020] The following will combine Figures 1 to 7 Various embodiments based on the technical concept of this disclosure are described respectively.
[0021] <First Embodiment>
[0022] The load drive circuit according to the first embodiment of this disclosure can be configured to include two drive branches, namely a first drive branch and a second drive branch. Its schematic block diagram is shown below. Figure 1 As shown, each of the first and second drive branches is coupled between the AC input terminal and the dual-channel load, and is configured to provide a current path between the AC input terminal and the dual-channel load during the positive and negative half-cycles of the AC power supplied at the AC input terminal, respectively; each of the first and second drive branches constitutes a separate current path connecting the AC power input terminal and the first and second channel loads. That is, the current in the first drive branch and the current in the second drive circuit are 180° out of phase.
[0023] Note that, unless otherwise specified, statements such as A is connected / coupled to B, or C is connected / coupled between A and B do not preclude the existence of other components between A and B, C and A, or C and B. In other words, A and B, C and A, or C and B can be directly electrically connected or electrically connected via intermediate components.
[0024] Specifically, the first drive branch is configured to provide a first current to the first channel load and the second channel load during the positive half-cycle of the AC power used to provide drive power to the loads; the second drive branch is configured to provide a second current to the first channel load and the second channel load during the negative half-cycle of the AC power. For example, the first channel load and the second channel load are connected in series and coupled to the first drive branch and the second drive branch. In one example, the first channel load and the second channel load may be connected in series with a configuration where the positive and negative voltage midpoints are grounded.
[0025] For example, the first drive branch may include a first unidirectional conducting element and a second unidirectional conducting element for supplying a first current, and the second drive branch may include a third unidirectional conducting element and a fourth unidirectional conducting element for supplying a second current. Here, the unidirectional conducting element may be a diode. The first channel load and the second channel load may be coupled between the first unidirectional conducting element and the second unidirectional conducting element of the first drive branch, and coupled between the third unidirectional conducting element and the fourth unidirectional conducting element of the second drive branch.
[0026] For example, AC power can be provided by a first transformer having a primary side and a secondary side. The first transformer is configured to transfer power from the power supply module via a primary side to a first tap and a second tap on the secondary side. In one example, a first unidirectional conducting element and a second unidirectional conducting element are coupled between the first tap and the second tap and arranged to allow a first current to flow from the first tap to the second tap; and a third unidirectional conducting element and a fourth unidirectional conducting element are coupled between the first tap and the second tap and arranged to allow a second current to flow from the second tap to the first tap. This ensures that the first channel load and the second channel load are driven throughout the entire AC cycle, thereby improving circuit efficiency, reducing the average drive current, and mitigating heat generation effects.
[0027] Furthermore, the load drive circuit also includes a filter capacitor shared by the first drive branch and the second drive branch. This filter capacitor is coupled between the first and second unidirectional conducting elements of the first drive branch, and between the third and fourth unidirectional conducting elements of the second drive branch. This shared structure reduces the number of required filter capacitors, lowers costs, and helps reduce ripple.
[0028] <Second Embodiment>
[0029] Figure 2 A schematic block diagram of a load drive circuit according to a second embodiment of the present disclosure is shown. Figure 2 As shown, except Figure 1In addition to the components shown, the load drive circuit can also be configured to include a detection module, a controller, and a power supply module.
[0030] For example, a detection module acquires a detection signal representing the electrical characteristics of the load and provides the detection signal to a controller. The detection signal may include, for example, a voltage signal at a specific location acquired by a voltage detector and / or a current signal at a specific location acquired by a current detector, etc. The controller receives the detection signal provided by the detection module and performs control based on the detection signal. Specifically, the controller can perform overvoltage or undervoltage protection and / or control a first current or a second current based on the detection signal. Thus, the current on the load can be adjusted based on feedback to keep it operating within an ideal predetermined range, and overvoltage or undervoltage can be prevented.
[0031] For example, the detection module is configured to perform differential detection on the voltages of the first channel load and the second channel load to obtain a first sense voltage indicating the degree of deviation of the drive voltage of the first channel load or the second channel load from a reference value, and to provide the first sense voltage to the controller. The controller is configured to determine whether the first sense voltage is outside a predetermined range, and to implement overvoltage protection if the first sense voltage exceeds the upper limit of the predetermined range, and to implement undervoltage protection if the first sense voltage is below the lower limit of the predetermined range.
[0032] In addition, the detection module can also be configured to sense the first current and the second current, and provide a second sensing voltage representing the sensing result to the controller, which adjusts the AC power according to the second sensing voltage to control the first current or the second current, such as increasing or decreasing the first current or the second current.
[0033] For example, a power supply module providing power may include: a second transformer, two signal amplification modules connected to the secondary side of the second transformer, and a power conversion module. The primary side of the second transformer is connected to a drive voltage output from a controller, and the power conversion module includes two controllable switches. These two controllable switches control the supply of AC power to the first transformer based on the output of the signal amplification modules.
[0034] The following embodiments will describe the load driving circuit of this disclosure using LED units as the driven load as an example. Exemplarily, the first channel load and the second channel load each include one or more LED units.
[0035] <Third Embodiment>
[0036] Figure 3A circuit diagram of a load driving circuit 1 according to a third embodiment of the present disclosure is shown. The load driven by the load driving circuit 1 includes a first-channel load LED1 and a second-channel load LED2. The first-channel load LED1 has a positive terminal LED1+ and a negative terminal LED1-, and the second-channel load LED2 has a positive terminal LED2+ and a negative terminal LED2-. The negative terminal LED1- of the first-channel load LED1 is connected to the positive terminal LED2+ of the second-channel load LED2. In other words, LED1 and LED2 are connected in series. It should be noted that only the case of one channel load including one LED is shown here, but this is not limiting. Each channel load can include multiple LEDs, and the number of LEDs in the two channels can be the same or different.
[0037] Load drive circuit 1 is coupled between the AC power source (the input of the AC power source) that provides drive power to the load and the load. As a non-limiting example, the AC power source is... Figure 3 The example shown is provided by the secondary side of transformer T2, which has taps 7 and 8. For ease of description, it is agreed here that during the positive half-cycle of the AC power, tap 7 on the secondary side of transformer T2 has a positive voltage and tap 8 has a negative voltage; during the negative half-cycle of the AC power, tap 7 has a negative voltage and tap 8 has a positive voltage.
[0038] The load drive circuit 1 includes a first drive branch and a second drive branch in parallel. The first drive branch is configured to provide a first current to the first channel load and the second channel load during the positive half-cycle of the AC power used to provide drive power to the load; the first drive branch includes diodes D3 and D5, wherein the anode terminal of diode D3 is connected to tap 7 on the secondary side of transformer T2, the cathode terminal of diode D3 is connected to the positive terminal LED1+ of the first channel load LED1, the anode terminal of diode D5 is connected to the negative terminal LED2- of the second channel load LED2, and the cathode terminal of diode D5 is connected to tap 8.
[0039] The second drive branch is configured to provide a second current to the first channel load and the second channel load during the negative half-cycle of the AC power used to provide drive power to the load; the second drive branch includes diodes D6 and D4, wherein the anode terminal of diode D6 is connected to tap 8 on the secondary side of transformer T2, the cathode terminal of diode D6 is connected to the positive terminal LED1+ of the first channel load LED1, the anode terminal of diode D4 is connected to the negative terminal LED2- of the second channel load LED2, and the cathode terminal of diode D4 is connected to tap 7.
[0040] Thus, each of the first and second drive branches constitutes a separate current path connecting the AC power supply to the first and second channel loads. As previously mentioned, the currents in the first and second drive branches are 180° out of phase.
[0041] As a non-restrictive example, Figure 3 A filter capacitor C3 shared by the first and second drive branches is shown. One end of the filter capacitor C3 is connected to the cathode terminals of diodes D3 and D6, and to the positive terminal LED1+ of the first channel load LED1; the other end of the filter capacitor C3 is connected to the anode terminals of diodes D5 and D4, and to the negative terminal LED2- of the second channel load LED2. However, in other further embodiments, this filter capacitor structure may be omitted or replaced with other known filter circuit structures.
[0042] Furthermore, as a non-restrictive example, Figure 3 Diodes D3 to D6 in the first and second drive branches are shown. However, in other further embodiments, at least one of diodes D3 to D6 may be replaced with other known unidirectional conducting elements, such as thyristors, transistors, or field-effect transistors.
[0043] The following is combined with Figure 4 and Figure 5 The operating modes and functions of the load drive circuit 1 shown in this embodiment will be explained separately.
[0044] AC power positive half-cycle
[0045] Figure 4 A schematic diagram of the current path driving the load in the first drive branch during the positive half-cycle of AC power is shown. During this positive half-cycle, tap 7 on the secondary side of transformer T2 has a positive voltage, and tap 8 has a negative voltage. At this time, diodes D3 and D5 in the first drive branch are forward biased and thus conduct, while diodes D4 and D6 in the second drive branch are reverse biased and thus cut off. The first current flows from tap 7 sequentially through the positive and negative terminals of diode D3 in the first drive branch, the positive terminal LED1+ and the negative terminal LED1- of the first channel load LED1, the positive terminal LED2+ and the negative terminal LED2- of the second channel load LED2, and the positive and negative terminals of diode D5 in the first drive branch, to tap 8 on the secondary side of transformer T2, thus forming a loop.
[0046] AC power negative half-cycle
[0047] Figure 5A schematic diagram of the current path of the second drive branch driving the load during the negative half-cycle of AC power is shown. During this negative half-cycle, tap 8 on the secondary side of transformer T2 has a positive voltage, and tap 7 has a negative voltage. At this time, diodes D6 and D4 in the second drive branch are forward biased and thus conduct, while diodes D5 and D3 in the first drive branch are reverse biased and thus cut off. The second current flows from tap 8 sequentially through the positive and negative terminals of diode D6 in the second drive branch, the positive terminal LED1+ and the negative terminal LED1- of the first channel load LED1, the positive terminal LED2+ and the negative terminal LED2- of the second channel load LED2, and the positive and negative terminals of diode D4 in the second drive branch, to tap 7 on the secondary side of transformer T2, thus forming another circuit.
[0048] Thus, in one complete cycle of AC power, the first drive branch supplies power to the first channel load LED1 and the second channel load LED2 connected in series with the first current in the positive half-cycle, while the second drive branch supplies power to the first channel load LED1 and the second channel load LED2 connected in series with the second current in the negative half-cycle, thus achieving full-cycle power supply.
[0049] Furthermore, as shown in the figure, the connection point between the negative terminal LED1- of the first channel load LED1 and the positive terminal LED2+ of the second channel load LED2 can be grounded to form a positive-negative voltage neutral grounding structure. In this way, during the positive and negative half-cycles, the voltage at this connection point is forced to be maintained at a neutral grounding voltage, such as ground voltage. Ideally, the positive terminal LED1+ of LED1 has a positive voltage within a predetermined range capable of driving the first channel load LED1, and the negative terminal LED2- of LED2 has a negative voltage within a predetermined range capable of driving the second channel load LED2, and both constitute a positive-negative voltage neutral grounding structure. Note that the amplitudes of the positive voltage of the positive terminal LED1+ of LED1 and the negative voltage of the negative terminal LED2- of LED2 can be equal or unequal; this is not limiting.
[0050] For ease of comparison, Figure 6 A load drive circuit 2 for powering a dual-channel LED load is shown in the prior art. Figure 6The LED load consists of two separate LEDs, LED1 and LED2. Transformer T2 provides AC voltages with positive and negative half-cycles at taps 7 and 12 on its secondary side. The load drive circuit 2 is configured such that tap 7 has a positive voltage and tap 12 has a negative voltage during the positive half-cycle of the AC current; the current direction is tap 7 → DC blocking capacitor C3 → diode D2 (which is forward biased and thus conducts) → LED1+ (i.e., the positive terminal of LED1) → LED1- (i.e., the negative terminal of LED1, which is grounded) → ground → diode D7 (the anode terminal of diode D7 is grounded) → tap 12, thus forming a loop. During the negative half-cycle of the alternating current, tap 12 has a positive voltage and tap 7 has a negative voltage; the current direction is tap 12 → diode D6 (which is forward biased and thus conducts) → LED2+ (i.e., the positive terminal of LED2) → LED2- (i.e., the negative terminal of LED2, which is grounded) → ground → diode D4 (the anode terminal of diode D4 is grounded) → DC blocking capacitor C3 → tap 7, thus forming a circuit.
[0051] As mentioned above, in Figure 6 In the load drive circuit 2 shown, LED1 conducts and operates only during the positive half-cycle of the AC current, and LED2 conducts and operates only during the negative half-cycle. Compared to full-cycle conduction, a larger average drive current is required for the same LED power; that is, diodes D3 to D6 need to withstand a larger current. Filter capacitor C4 only performs filtering during the positive half-cycle of the AC current, while filter capacitor C9 only performs filtering during the negative half-cycle. Furthermore, since the first-channel load LED1 and the second-channel load LED2 are in separate circuits, their forward conduction voltages will have a voltage difference, which is unavoidable. To prevent circuit instability, a DC blocking capacitor C3 is connected in series. The operating voltage of C3 is the difference between the forward conduction voltages of the first-channel load LED1 and the second-channel load LED2. Typically, this DC blocking capacitor C3 has high specifications and is expensive.
[0052] Compared with the existing load drive circuit 2, such as Figures 3 to 5 The load drive circuit 1 shown according to the embodiments of this disclosure has the following technical advantages:
[0053] because Figure 6 In the load drive circuit 2 shown, diodes D2 and D7 operate only during the positive half-cycle of the AC power, and the first load is driven only during this positive half-cycle; similarly, diodes D6 and D4 operate only during the negative half-cycle of the AC power, and the second load is driven only during this negative half-cycle. Therefore, the average current across diodes D2, D7, D6, and D4 in load drive circuit 2 is relatively large. In comparison, as... Figures 3 to 5In the load drive circuit 1 shown, the first channel load LED1 and the second channel load LED2 are connected in series and the midpoint of the positive and negative voltages is grounded. They are driven by the first drive branch during the positive half-cycle and by the second drive branch during the negative half-cycle. As a result, compared with the load drive circuit 2, under the same LED power, the average current flowing through diodes D3 and D5 in the first drive branch and diodes D6 and D4 in the second drive branch is halved. The heat dissipation caused by conduction loss in the diodes is also significantly reduced, resulting in a lower temperature. This reduces the current or temperature requirements of the diodes, thereby reducing costs and losses.
[0054] Furthermore, due to such Figures 3 to 5 The first channel load LED1 and the second channel load LED2 in the load drive circuit 1 shown are connected in series. Even when there is a voltage difference between the forward conduction voltages of the first channel load LED1 and the second channel load LED2, it is not necessary to... Figure 6 The DC blocking capacitor C3 shown here saves on components and has a cost advantage.
[0055] Furthermore, due to such Figures 3 to 5 In the load drive circuit 1 shown, the first channel load LED1 and the second channel load LED2 are connected in series. Only a filter capacitor C3 needs to be coupled between the positive terminal LED1+ of the first channel load LED1 and the negative terminal LED2- of the second channel load LED2. Compared to... Figure 6 Compared to the first-path load-only filter capacitor C4 and the second-path load-only filter capacitor C9 shown, the number of filter capacitors in the load drive circuit of this disclosure is halved, thus improving utilization efficiency.
[0056] Figure 6 The first load's individual filter capacitor C4, as shown, performs filtering only during the positive half-cycle of a complete AC voltage cycle; the second load's individual filter capacitor C9 performs filtering only during the negative half-cycle of a complete AC voltage cycle. In contrast, the present application's... Figures 3 to 5 In the load drive circuit 1 shown, the filter capacitor C3 performs filtering during both the positive and negative half-cycles of a complete AC voltage cycle, which is equivalent to doubling the operating frequency of the filter capacitor C3. Therefore, it is related to... Figure 6 Compared to C9, the capacitance value of the filter capacitor C4 can be reduced by half for the same ripple peak value, further reducing the cost of the filter capacitor C3 in the load drive circuit 1.
[0057] <Fourth Embodiment>
[0058] Figure 7 A circuit diagram of a load drive circuit 3 according to a fourth embodiment of the present disclosure is shown.
[0059] The load drive circuit 3 shown in this embodiment includes a first drive branch and a second drive branch, each of which constitutes a separate current path connecting the AC power supply and the first-channel load and the second-channel load. The load drive circuit 3 has a structure similar to that of the load drive circuit 1 shown in the third embodiment. Similar to the third embodiment, the load of the load drive circuit 3 also has a positive and negative voltage neutral grounding structure with the first-channel load LED1 and the second-channel load LED2 connected in series.
[0060] and Figure 3 The load drive circuit 1 shown in the embodiment differs from the one shown in the following way: Figure 7 The load drive circuit 3 of the illustrated embodiment further includes a detection module 32, a controller 33, a transformer T2, and a power supply module 31 coupled between the primary side of the transformer T2 and the controller 33.
[0061] The structures of the power supply module 31, the detection module 32, and the controller 33 are described below. As a non-limiting example, such as... Figure 7 As shown, the power supply module 31 includes: a transformer T1, two signal amplification modules connected to the secondary side of the transformer T1, and a power conversion module 311, wherein the primary side of the second transformer is connected to the drive voltage output from the controller 33. Figure 7 The diagram shows a power conversion module 311 consisting of two controllable switching transistors Q1 and Q2, and correspondingly, two signal amplification modules 312 and 313 connected to the secondary side of transformer T1.
[0062] Power conversion module 311 is coupled to voltage source VIN, and is used to convert the voltage of voltage source VIN into a desired AC voltage and output it to taps 1 and 4 on the primary side of transformer T2. Power conversion module 311 includes controllable switching transistors Q1 and Q2. As a non-limiting embodiment, Figure 7 The power conversion module 311 shown is configured to be coupled to the primary side of transformer T2 and capacitor C2 connected in an LLC circuit topology, wherein the primary side of transformer T2 integrates leakage inductance L, thereby forming an integrated LLC topology with capacitor C2.
[0063] Transformer T2 is configured to transfer power from power conversion module 311 via taps 7 and 8 on the primary side to the secondary side. Each signal amplification module receives a separate drive voltage signal from the controller, amplifies it, and outputs it to the control terminal of the corresponding controllable switching transistor. However, as... Figure 7The number of controllable switching transistors and the circuit topology shown in the power conversion module 311 are for the purpose of brief illustration of this embodiment and are not intended to limit the scope of this disclosure.
[0064] For example, Figure 7 In the power conversion module 311 shown, the first terminal of the controllable switching transistor Q1 is connected to the voltage source VIN, the second terminal of the controllable switching transistor Q1 is connected to the first terminal of the controllable switching transistor Q2, and the second terminal of the controllable switching transistor Q2 is connected to the neutral ground point (ground). The node formed by the connection of Q1 and Q2 is also connected to tap 1 on the primary side of transformer T2, and a capacitor C2 is connected between tap 4 on the primary side of transformer T2 and the neutral ground point (ground). The third terminals (control terminals) of the controllable switching transistors Q1 and Q2 are respectively connected to the outputs of signal amplification modules 312 and 313. The circuit composed of controllable switching transistors Q1 and Q2 is used to perform high-frequency switching in a predetermined mode according to the drive signal received by its control terminal, thereby controlling the voltage waveform output from the voltage source VIN to the taps 1 and 4 on the primary side of transformer T2, and thereby controlling the voltage waveform on both sides of taps 7 and 8 on the secondary side of transformer T2.
[0065] Signal amplification modules 312 and 313 have similar structures. Taking signal amplification module 312 as an example, it includes resistors R1, R3, and R5 connected in series between taps 5 and 6 of an independent winding on the secondary side of the voltage transformer T1, and a diode D1 connected in reverse parallel across resistor R3. The cathode terminal of diode D1 is connected to the node formed by the connection of resistors R1 and R3, and the anode terminal of diode D1 is connected to the node formed by the connection of resistors R3 and R5 to form the reverse parallel connection. The node formed by the connection of the anode terminal of diode D1, resistors R3 and R5 is also connected to the control terminal of controllable switching transistor Q1, and the node formed by the connection of resistor R5 and tap 5 of the independent winding is also connected to the second terminal of controllable switching transistor Q1.
[0066] Similarly, the signal amplification module 313 includes resistors R2, R4, and R6 connected in series between taps 4 and 3 of another independent winding on the secondary side of the voltage transformer T1, and diode D2 connected in reverse parallel across resistor R4; the node formed by the anode terminal of diode D2, resistors R4 and R6 is also connected to the control terminal of controllable switching transistor Q2, and the node formed by resistor R6 and tap 3 of the independent winding is also connected to the second terminal of controllable switching transistor Q1.
[0067] The detection module 32 is used to detect the voltage or current signal (representing a specific electrical characteristic of the load drive circuit) at a specific location of the load drive circuit 3 or the voltage or current signal (representing a specific electrical characteristic of the load) of the load, and provides the obtained detection signal to the controller. The controller performs overvoltage or undervoltage protection and / or controls the current supplied to the load based on the detection signal.
[0068] Figure 7 The detection module 32 is shown as one example. Figure 7 The detection module 32 shown includes a first detection module and a second detection module. The first detection module is configured to perform differential detection on the voltages of the first channel load LED1 and the second channel load LED2 to obtain a first sense voltage indicating the degree of deviation of the drive voltage of either the first channel load LED1 or the second channel load LED2 from a reference value, and to provide the first sense voltage to the controller 33. The controller 33 is configured to determine whether the first sense voltage is outside a predetermined range, and to implement overvoltage protection if the first sense voltage exceeds the upper limit of the predetermined range, and undervoltage protection if the first sense voltage is below the lower limit of the predetermined range. The second detection module is configured to sense the current flowing through LED1 and LED2, and to provide a second sense voltage representing the sensing result to the controller 33. The controller 33 is configured to adjust the AC power according to the second sense voltage to control the current flowing through LED1 and LED2 (i.e., the first current or the second current).
[0069] The first detection module includes resistors R8, R9, and R7. Resistors R8 and R9 are connected in series between the positive terminal LED1+ of the first channel load LED1 and the negative terminal LED2- of the second channel load LED2. One end of resistor R7 is connected between resistors R8 and R9, and the other end of resistor R7 is connected to a neutral ground point. For example, the current flowing through resistor R8 is greater than the current flowing through resistor R9. The first detection module is configured to detect the voltage signal at the connection point of resistors R8 and R9, and the measured voltage value VSEN is used as the first sense voltage. By setting the resistance values of resistors R8 and R9 such that the current flowing through resistor R8 is greater than the current flowing through resistor R9, the current difference flowing through resistor R7 and the neutral ground point generates the first sense voltage VSEN, therefore the first sense voltage VSEN has a positive voltage. When the first sensed voltage VSEN exceeds the upper limit of a predetermined range (exemplarily, 0.7V to 3V), the overvoltage protection of the controller 33 connected to the first sensed voltage VSEN is triggered, and the controller performs overvoltage protection action; when the first sensed voltage VSEN is lower than the lower limit of a predetermined range, the undervoltage protection of the controller 33 connected to the first sensed voltage VSEN is triggered, and the controller performs undervoltage protection action.
[0070] The second detection module includes a resistor R10 connected between the negative terminal LED1- of the first channel load LED1 and the positive terminal LED2+ of the second channel load LED2. The node formed by the connection of resistor R10 and the positive terminal LED2+ is connected to a neutral ground point. The second detection module is configured to detect the voltage signal at the connection point of resistor R10 and the negative terminal LED1-. The measured voltage value is used as a second sense voltage to represent the first current or the second current ISEN flowing through the first channel load LED1 and the second channel load LED2. The controller 33 is configured to control the first current or the second current based on the second sense voltage, for example, by adjusting its magnitude.
[0071] The following description, in conjunction with the first detection module, illustrates this point. Figure 7 The operating mode of the load drive circuit 3 in the illustrated embodiment.
[0072] Normal mode
[0073] In normal mode, the controller 33 of the load drive circuit 3 generates a drive voltage signal, which drives the power conversion module 311 to convert the voltage of the voltage source VIN into the desired AC voltage and transmit it to the first channel load LED1 and the second channel load LED2 via the transformer T2 and the first and second drive branches. The detection module 32 outputs the detected first sense voltage to the controller 33. When the first sense voltage is within a predetermined range between a first predetermined threshold and a second predetermined threshold (here, the second predetermined threshold is defined as greater than the first predetermined threshold), it indicates that the drive voltage of LED1 and LED2 is within the allowable range, and LED1 and LED2 are in normal working condition. The controller 33 determines that the power conversion module 311 is in normal working mode based on the judgment result of the voltage value VSEN between the first and second predetermined thresholds.
[0074] Abnormal mode
[0075] If the voltage value VSEN received by the controller 33 from the detection module 32 is greater than the second predetermined threshold, overvoltage protection is performed. Specifically, in this case, the controller 33 determines that the driving voltage amplitude of the positive terminal LED1+ of the first channel load LED1 is too large and exceeds the allowable range (or is much larger than the reference value), and the controller 33 implements overvoltage protection by shutting down the driving voltage signal.
[0076] If the voltage value VSEN received by the controller 33 from the detection module 32 is less than a first predetermined threshold, undervoltage protection is performed. Specifically, in this case, the controller 33 determines that the driving voltage amplitude of the positive terminal LED1+ of the first channel load LED1 is too small and exceeds the allowable range (or is much smaller than the reference value), and the controller 33 implements undervoltage protection by turning off the driving voltage signal.
[0077] The overvoltage and undervoltage protection of LED1 are discussed here as examples, and the same applies to LED2, so they will not be described again.
[0078] In summary, Figure 7 The load drive circuit 3 shown has the same characteristics as... Figures 3 to 5 The technical advantages of the load drive circuit 1 shown are similar and will not be repeated here. In addition, the load drive circuit 3 can adjust the current or voltage of the first channel load or the second channel load based on the detection signal fed back by the detection module 32 so that the current or voltage is stabilized within a predetermined operating range or overvoltage or undervoltage protection is implemented under abnormal conditions. It has higher operating efficiency and better durability, thereby having lower operating costs and higher performance.
[0079] In one embodiment according to this disclosure, the controller employs a backlight control chip of model OZ9976A / B. This backlight control chip is a low-voltage control chip that outputs a low-voltage drive signal, which is then output to... Figure 7 On the primary side of the transformer T1 shown, the drive signal is amplified by a signal amplification circuit to drive the controllable switching transistor to perform power conversion. The controller 33 with this low-voltage control chip can be integrated with the detection module 32, the first channel load and the second channel load on the low-voltage side, and is electrically isolated from the power supply module 31 on the relatively high-voltage side.
[0080] In one embodiment according to this disclosure, the first channel load and the second channel load each include one or more LED units.
[0081] In one embodiment of the present disclosure, a light source device is provided, comprising: a first LED group including one or more LED units; a second LED group including one or more LED units; and a load driving circuit according to the foregoing embodiments, wherein the first LED group is a first channel load and the second LED group is a second channel load.
[0082] In the embodiments according to this disclosure above, a method for driving a load using the load driving circuit shown in the embodiment is also provided. This method has been described in detail in conjunction with the device structure of the above embodiments, and will not be repeated here.
[0083] It should also be noted that in the apparatus, method, and system disclosed herein, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions to this disclosure.
[0084] Finally, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Furthermore, unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0085] While embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, it should be understood that the embodiments described above are merely illustrative and do not constitute a limitation thereof. Those skilled in the art can make various modifications and alterations to the above embodiments without departing from the spirit and scope of the present disclosure. Therefore, the scope of the present disclosure is defined only by the appended claims and their equivalents.
Claims
1. A load driving circuit for driving a first channel load and a second channel load, comprising: The first drive branch is configured to provide a first current to the first channel load and the second channel load during the positive half-cycle of the AC power used to provide drive power to the load; as well as The second drive branch is configured to provide a second current to the first channel load and the second channel load during the negative half-cycle of the AC power. Each of the first drive branch and the second drive branch constitutes a separate current path connecting the input terminal of the AC power to the first channel load and the second channel load.
2. The load drive circuit according to claim 1, wherein, The first driving branch includes a first unidirectional conducting element and a second unidirectional conducting element for supplying the first current, and the second driving branch includes a third unidirectional conducting element and a fourth unidirectional conducting element for supplying the second current.
3. The load drive circuit according to claim 2 further includes a filter capacitor shared by the first drive branch and the second drive branch, wherein, The filter capacitor is coupled between the first unidirectional conducting element and the second unidirectional conducting element of the first driving branch, and is also coupled between the third unidirectional conducting element and the fourth unidirectional conducting element of the second driving branch.
4. The load drive circuit according to claim 2, wherein, The first channel load and the second channel load are connected in series and coupled to the first drive branch and the second drive branch.
5. The load drive circuit according to claim 4, wherein, The first channel load and the second channel load are connected in series with a structure that grounds the positive and negative voltage midpoint.
6. The load drive circuit according to claim 5, wherein, The first channel load and the second channel load each have a first end and a second end. The second end of the first channel load is coupled to the first end of the second channel load and coupled to the neutral grounding point to form the structure of positive and negative voltage midpoint grounding.
7. The load drive circuit according to claim 4, wherein, The first channel load and the second channel load are coupled between the first unidirectional conducting element and the second unidirectional conducting element of the first drive branch, and are coupled between the third unidirectional conducting element and the fourth unidirectional conducting element of the second drive branch.
8. The load drive circuit of claim 2 further includes a first transformer having a primary side and a secondary side, the first transformer being configured to transmit power from the power supply module via the primary side to a first tap and a second tap on the secondary side; in, The first unidirectional conducting element and the second unidirectional conducting element are coupled between the first tap and the second tap and are arranged to allow the first current to flow from the first tap to the second tap; as well as The third unidirectional conducting element and the fourth unidirectional conducting element are coupled between the first tap and the second tap and are arranged to allow the second current to flow from the second tap to the first tap.
9. The load drive circuit according to claim 5 further includes a detection module and a controller, wherein, The detection module detects a detection signal representing the electrical characteristics of the load and provides the detection signal to the controller, which performs overvoltage or undervoltage protection and / or controls the first current or the second current based on the detection signal.
10. The load drive circuit according to claim 9, wherein, The detection module is configured to perform differential detection on the voltages of the first channel load and the second channel load to obtain a first sense voltage indicating the degree of deviation of the drive voltage of the first channel load or the second channel load from a reference value, and to provide the first sense voltage to the controller.
11. The load drive circuit according to claim 10, wherein, The controller is configured to determine whether the first sensed voltage is outside a predetermined range, and to implement overvoltage protection if the first sensed voltage exceeds the upper limit of the predetermined range, and to implement undervoltage protection if the first sensed voltage is below the lower limit of the predetermined range.
12. The load drive circuit according to claim 10, wherein, The detection module includes a first resistor, a second resistor, and a third resistor. The first resistor and the second resistor are connected in series between the first end of the first channel load and the second end of the second channel load. One end of the third resistor is connected between the first resistor and the second resistor, and the other end of the third resistor is connected to the neutral ground point.
13. The load drive circuit according to claim 12, wherein, The current through the first resistor is greater than the current through the second resistor, so that the difference between the two currents generates the first sensing voltage through the third resistor.
14. The load drive circuit according to claim 10, wherein, The detection module is also configured to sense the first current and the second current, and to provide a second sensing voltage representing the sensing result to the controller, which adjusts the AC power according to the second sensing voltage to control the first current or the second current.
15. The load drive circuit according to claim 14, wherein, The detection module includes a fourth resistor coupled between the second end of the first channel load and the first end of the second channel load, and one end of the fourth resistor coupled to the first end of the second channel load is connected to a neutral ground point.
16. The load drive circuit according to claim 8, wherein, The power supply module includes: a second transformer, two signal amplification modules connected to the secondary side of the second transformer, and a power conversion module, wherein the primary side of the second transformer is connected to the drive voltage output from the controller, and the power conversion module includes two controllable switches.
17. The load drive circuit according to claim 16, wherein, Each of the two signal amplification modules is connected to an independent winding on the secondary side of the second transformer, and is used to amplify the drive voltage of the controller and output it to the control terminal of a corresponding one of the two controllable switches. Each of the two signal amplification modules includes: A fifth resistor, a sixth resistor, and a seventh resistor are connected in series between the two taps of the independent winding, and a fifth unidirectional conducting element is connected in reverse parallel across the sixth resistor. The connection point of the sixth resistor and the seventh resistor is also connected to the control terminal of the corresponding controllable switch.
18. The load drive circuit according to any one of claims 9 to 15, wherein, The controller is a backlight control chip with model number OZ9976A / B.
19. The load drive circuit according to any one of claims 1 to 17, wherein, The first channel load and the second channel load each include one or more LED units.
20. The load drive circuit according to any one of claims 2 to 17, wherein each of the first unidirectional conducting element, the second unidirectional conducting element, the third unidirectional conducting element, and the fourth unidirectional conducting element comprises a diode.
21. A light source device, comprising: A first LED group comprising one or more LED units; A second LED group comprising one or more LED units; as well as The load driving circuit according to any one of claims 1 to 20, wherein the first LED group is a first channel load and the second LED group is a second channel load.
22. A method for driving a load using a load drive circuit according to any one of claims 1 to 20.