Power supply circuit, control method, and lighting apparatus

Abstract

The invention discloses a power supply circuit, a control method, and a lighting apparatus. The power supply circuit includes: an input terminal configured to receive an input voltage; a rectifying circuit configured to be connected to one of the input terminals; a voltage conversion circuit configured to be connected to the rectification circuit and output a DC voltage (Vo); a controller configured to output a control signal to the voltage conversion circuit; a voltage detector configured to detect whether the input voltage is a DC voltage or an AC voltage, and output a detection signal corresponding to a detection result; and an oscillation circuit configured to output an oscillation signal when the voltage detector detects a DC voltage, and stop outputting the oscillation signal when the voltage detector detects an AC voltage; the oscillation signal output by the oscillation circuit is provided to the controller to change an operating frequency of the controller. As a result, the EMI result of the power supply circuit at the DC input will be improved at a lower cost and in a smaller space.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of circuits, and more particularly to power supply circuits, control methods, and lighting devices. Background Art

[0002] This section presents aspects that may be useful for a better understanding of the present disclosure. Therefore, statements in this section should be read in this context and should not be construed as an admission of what is or is not prior art.

[0003] LED (Light Emitting Diode) drivers typically need to operate under AC (Alternative Current) input and DC (Direct Current) input (176V - 280V), which is an emergency application. If the LED driver is connected to the AC mains, the operating frequency range of the LED driver is from dozens to hundreds of kHz. Therefore, the noise energy is dispersed to various frequency points and is more likely to pass CISPER. When operating under DC input, the LED driver operates in the conduction mode at a fixed operating frequency, so it is difficult to pass CISPER.

[0004] Existing market solutions typically use an MCU (Micro Controlling Unit) to generate a signal with a jitter frequency and input the signal into the controller of the LED driver. This technology changes the operating frequency under DC input, so better EMI (Electro Magnetic Interference) results can be obtained. Summary of the Invention

[0005] Figure 1 is a diagram of an LED driver in the related art. As Figure 1 shown, the MCU 10 is used to detect whether the input signal is an AC signal or a DC signal. When the input signal is a DC signal, the MCU 10 generates a signal with a jitter frequency and inputs the signal into the controller 11 to achieve a change in the operating frequency under DC input, thereby helping to improve the EMI results of the LED driver 100. As Figure 1 shown, the MCU 10 is located on the secondary side of the transformer 12 of the LED driver 100, and the optical couplers 13, 14 are used to isolate the primary side and the secondary side of the transformer 12.

[0006] The inventors of the present disclosure are in Figure 1The following limitations were found. For example, MCUs are expensive, require software, and optical couplers may take up space on a PCBA (Printed Circuit Board Assembly).

[0007] Generally speaking, embodiments of the present disclosure provide a power supply circuit, a control method, and a lighting device. In an embodiment, a voltage detector can detect whether an input voltage is a DC voltage or an AC voltage. When a DC input voltage is detected, an oscillation circuit outputs an oscillation signal to a controller to change its operating frequency. Therefore, the EMI results of the power supply circuit under DC input can be improved at lower cost and in less space.

[0008] In a first aspect, a power supply circuit is provided, the power supply circuit comprising:

[0009] Input terminals (x1-a, x1-b) configured to receive an input voltage;

[0010] A rectification circuit configured to be connected to one of the input terminals;

[0011] A voltage conversion circuit configured to be connected to the rectification circuit and output a DC voltage (Vo);

[0012] A controller configured to output a control signal to the voltage conversion circuit;

[0013] A voltage detector configured to detect whether the input voltage is a DC voltage or an AC voltage and output a detection signal corresponding to the detection result; and

[0014] An oscillation circuit configured to output an oscillation signal when the voltage detector detects a DC voltage and stop outputting the oscillation signal when the voltage detector detects an AC voltage;

[0015] The oscillation signal output by the oscillation circuit is provided to the controller to change the operating frequency of the controller.

[0016] In at least one embodiment, when the voltage detector detects a DC voltage, the detection signal enables the oscillation circuit;

[0017] When the voltage detector detects an AC voltage, the detection signal disables the oscillation circuit.

[0018] In at least one embodiment, the voltage detector is connected to an output node of the rectification circuit and detects whether the input voltage is a DC voltage or an AC voltage based on the voltage at the output node.

[0019] In at least one embodiment, the voltage detector includes:

[0020] A first switch (M60);

[0021] A first resistor (R64) and a first capacitor (C64), the first resistor and the first capacitor being connected in parallel between the output node of the rectifier circuit and the control terminal of the first switch (M60); and

[0022] A second resistor (R63) and a second capacitor (C49), the second resistor and the second capacitor being connected in parallel between the control terminal of the first switch (M60) and the ground terminal (GND);

[0023] A first terminal of the first switch is connected to the ground terminal, and a second terminal of the first switch is connected to the oscillation circuit.

[0024] In at least one embodiment, the voltage detector further includes:

[0025] A first diode (D22), an anode of the first diode being connected to a first connection node of the first resistor (R64) and the first capacitor (C64), and a cathode of the first diode being connected to a second connection node of the second resistor (R63) and the second capacitor (C49).

[0026] In at least one embodiment, the voltage detector further includes:

[0027] A second diode (D23), an anode of the second diode being connected to the ground terminal, and a cathode of the second diode being connected to the first connection node of the first resistor (R64) and the first capacitor (C64).

[0028] In at least one embodiment, the oscillation circuit includes:

[0029] A self-excited oscillator that outputs a rectangular wave from an output terminal.

[0030] In at least one embodiment, the oscillation circuit further includes:

[0031] A third resistor (R58) and a third capacitor (C47), the third resistor and the third capacitor being connected in series between the output terminal and the ground terminal.

[0032] In at least one embodiment, a third connection node of the third resistor (R58) and the third capacitor (C47) is connected to the voltage detector to receive the detection signal.

[0033] In a second aspect, a control method for a power supply circuit is provided, the method comprising:

[0034] Rectifying an input voltage;

[0035] Detecting whether the input voltage is a DC voltage or an AC voltage, and outputting a detection signal corresponding to the detection result;

[0036] Generating an oscillation signal when the voltage detector detects a DC voltage, and stopping outputting the oscillation signal when the voltage detector detects an AC voltage;

[0037] Outputting a control signal according to the oscillation signal; and

[0038] Converting the rectified voltage into an output voltage.

[0039] In a third aspect, a lighting device is provided, the lighting device comprising a lighting module and a power supply circuit according to any one of the embodiments, the power supply circuit being connected to the lighting module and supplying a DC voltage to the lighting module.

[0040] According to various embodiments of the present disclosure, a voltage detector can detect whether an input voltage is a DC voltage or an AC voltage. When a DC input voltage is detected, an oscillation circuit outputs an oscillation signal to a controller to change its operating frequency. Accordingly, the EMI results of the power supply circuit under DC input can be improved at lower cost and in a smaller space. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] By way of example, and with reference to the following detailed description of the accompanying drawings, the above and other aspects, features and advantages of various embodiments of the present disclosure will become more apparent, in which like reference numerals or letters are used to denote like or equivalent elements. The drawings are shown for the purpose of facilitating a better understanding of the embodiments of the present disclosure and are not necessarily drawn to scale, in which:

[0042] Figure 1 is a diagram of an LED driver in the related art;

[0043] Figure 2 is a diagram of a power supply circuit according to at least one embodiment of the present disclosure;

[0044] Figure 3 is a diagram of a power supply circuit according to at least one embodiment of the present disclosure;

[0045] Figure 4 shows a flowchart of a control method 400 of a power supply circuit. DETAILED DESCRIPTION

[0046] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that the purpose of discussing these embodiments is only to enable those skilled in the art to better understand the present disclosure and thus implement the present disclosure, rather than to impose any limitation on the scope of the present disclosure.

[0047] As used herein, the terms "first" and "second" refer to different elements. Unless the context clearly indicates otherwise, the singular forms "a" and "an" are also intended to include the plural forms. As used herein, the terms "comprising," "including," "having," and / or "containing" specify the presence of the stated features, elements, and / or components, etc., but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. The term "based on" should be understood as "at least partially based on." The terms "one embodiment" and "embodiment" should be understood as "at least one embodiment." The term "another embodiment" should be understood as "at least one other embodiment." Other explicit and implicit definitions may be included below.

[0048] The first aspect of the embodiment

[0049] In a first aspect of an embodiment, a power supply circuit is provided.

[0050] Figure 2 is a diagram of a power supply circuit according to at least one embodiment of the present disclosure. As Figure 2 shown, the power supply circuit 2 includes input terminals x1-a and x1-b, a rectifier circuit 21, a voltage conversion circuit 22, a controller 23, a voltage detector 24, and an oscillation circuit 25.

[0051] In at least one embodiment, the input terminals x1-a and x1-b are configured to receive an input voltage Vin.

[0052] The rectifier circuit 21 is configured to be connected to the input terminal x1-a. For example, the rectifier circuit 21 is a rectifier bridge composed of four diodes D01A, D01B, D01C, and D01D. The output node N1 of the rectifier circuit 21 outputs a rectified voltage Uo.

[0053] The voltage conversion circuit 22 is configured to be connected to the rectifier circuit 21 and output a DC voltage Vo. For example, the voltage conversion circuit 22 includes a switch M10 (e.g., a MOS transistor), a transformer T, and at least one resistor (e.g., resistors R13, R14, and R15 connected in parallel). The primary coil of the transformer T is connected between the output node N1 and the drain of the switch M10. At least one resistor is connected between the source of the switch M10 and the ground terminal GND.

[0054] As Figure 2As shown, the voltage conversion circuit 22 further includes a diode D02C and a capacitor C80A. The diode D02C and the capacitor C80A are connected to the secondary coil of the transformer T. The connection node of the diode D02C and the capacitor C80A outputs a DC voltage Vo.

[0055] The controller 23 is configured to output a control signal to the voltage conversion circuit 22 to control the voltage conversion operation. For example, the control signal is a PWM (Pulse Width Modulation) signal and is provided to the gate of the switch M10 to control the on state of the switch M10.

[0056] The voltage detector 24 is configured to detect whether the input voltage Vin is a DC voltage or an AC voltage and output a detection signal DS corresponding to the detection result.

[0057] The oscillation circuit 25 is configured to output an oscillation signal when the voltage detector 24 detects a DC voltage and stop outputting the oscillation signal when the voltage detector 24 detects an AC voltage.

[0058] The oscillation signal output by the oscillation circuit 25 is provided to the controller 23 to change the operating frequency of the controller 23. For example, the oscillation signal is provided to the MULT or COMP pin of the controller 23.

[0059] The oscillation signal output by the oscillation circuit 25 may affect the operation of the controller 23, causing the input current of the controller 23 to follow the waveform of the oscillation signal, and thus causing the operating frequency of the controller 23 to also follow the waveform. Therefore, the noise energy of the power supply circuit 2 will be dispersed at different frequency points. Therefore, when the input voltage is a DC voltage, the power supply circuit 2 is more likely to pass CISPER.

[0060] In at least one embodiment, when the voltage detector 24 detects a DC voltage, the detection signal DS enables the oscillation circuit 25 so that the oscillation signal can be applied to the controller 23.

[0061] When the voltage detector 24 detects an AC voltage, the detection signal deactivates the oscillation circuit 25 so that the oscillation circuit 25 does not generate an oscillation signal and the operation of the controller 23 under AC input can be unaffected by the oscillation circuit 25.

[0062] Figure 3 is a diagram of a power supply circuit according to at least one embodiment of the present disclosure. Figure 3 An example of the voltage detector 24 and the oscillation circuit 25 is shown.

[0063] In at least one embodiment, as Figure 3As shown, the voltage detector 24 is connected to the output node N1 of the rectifier circuit 22. The voltage detector 24 can detect whether the input voltage Vin is a DC voltage or an AC voltage based on the voltage Uo at the output node N1.

[0064] As Figure 3 shown, the voltage detector 24 may include:

[0065] A first switch M60, such as a MOS transistor;

[0066] A first resistor R64 and a first capacitor C64, which are connected in parallel between the output node N1 of the rectifier circuit 22 and the control terminal (e.g., gate) of the first switch M60; and

[0067] A second resistor R63 and a second capacitor C49, which are connected in parallel between the control terminal (e.g., gate) of the first switch M60 and the ground terminal GND.

[0068] As Figure 3 shown, the first terminal (e.g., source) of the first switch M60 is connected to the ground terminal GND, and the second terminal (e.g., drain) of the first switch M60 is connected to the oscillation circuit 25. The second terminal (e.g., drain) of the first switch M60 can generate a detection signal.

[0069] As Figure 3 shown, the voltage detector 24 may further include a first diode D22. The anode of the first diode D22 is connected to the first connection node N12 of the first resistor R64 and the first capacitor C64. The cathode of the first diode D22 is connected to the second connection node N2 of the second resistor R63 and the second capacitor C49.

[0070] The voltage detector 24 may further include a second diode D23. The anode of the second diode D23 is connected to the ground terminal GND, and the cathode of the second diode D23 is connected to the first connection node N12 of the first resistor R64 and the first capacitor C64.

[0071] The oscillation circuit 25 includes a self-excited oscillator 251. The self-excited oscillator 251 can output a rectangular wave from the output terminal N3.

[0072] The self-excited oscillator 251 may include transistors Q1-a, Q1-b, capacitors C44, C46, resistors R45, R55, R56 and R57. The capacitors C44 and C46 can be alternately charged to output a rectangular wave. The working principle of the self-excited oscillator 251 can refer to the related art.

[0073] The oscillation circuit 25 may further include a third resistor R58 and a third capacitor C47 connected in series between the output terminal and the ground terminal. The third resistor R58 and the third capacitor C47 are used to filter out high-frequency components from the rectangular wave. In addition, a diode D21 is also included in the oscillation circuit 25.

[0074] As Figure 3 shown, a third connection node N31 of the third resistor R58 and the third capacitor C47 is connected to the voltage detector 24 to receive a detection signal output by the voltage detector 24.

[0075] When an AC voltage is input to X1-a, the first switch M60 is turned on, and when the third connection node N31 is set to a low level, the oscillation circuit 25 may not output an oscillation signal.

[0076] When an input DC voltage is input to X1-a, the first switch M60 may not be turned on, and the oscillation circuit 25 outputs an oscillation signal.

[0077] As can be seen in the above embodiments, the voltage detector can detect whether the input voltage is a DC voltage or an AC voltage. When a DC input voltage is detected, the oscillation circuit outputs an oscillation signal to the controller to change its operating frequency. Therefore, the EMI results of the power supply circuit under DC input can be improved at a lower cost and in a smaller space. In addition, the embodiments can be implemented by hardware.

[0078] The second aspect of the embodiment

[0079] In one embodiment, a control method for the power supply circuit of the first aspect of the embodiment is provided. Those contents that are the same as those in the first aspect of the embodiment are omitted.

[0080] Figure 4 A flowchart of the control method 400 of the power supply circuit is shown.

[0081] As Figure 4 shown, the method 400 includes:

[0082] Block 401: Rectify the input voltage;

[0083] Block 402: Detect whether the input voltage is a DC voltage or an AC voltage, and output a detection signal corresponding to the detection result;

[0084] Block 403: Generate an oscillation signal when the voltage detector detects a DC voltage, and stop outputting the oscillation signal when the voltage detector detects an AC voltage;

[0085] Block 404: Output a control signal according to the oscillation signal; and

[0086] Frame 405: Convert the rectified voltage into an output voltage.

[0087] In at least one embodiment, when a DC voltage is detected in block 402, the detection signal enables the oscillation circuit to output an oscillation signal; when an AC voltage is detected in block 402, the detection signal disables the oscillation circuit.

[0088] As can be seen in the above embodiments, the voltage detector can detect whether the input voltage is a DC voltage or an AC voltage. When the input DC voltage is detected, the oscillation circuit outputs an oscillation signal to the controller to change its operating frequency. Therefore, the EMI results of the power supply circuit under DC input can be improved at lower cost and with less space.

[0089] The third aspect of the embodiment

[0090] In one embodiment, a lighting device is provided. The lighting device includes a lighting module and a power supply circuit according to the first aspect of the embodiment.

[0091] In an embodiment, the power supply circuit is connected to the lighting module and provides a DC voltage to drive the lighting module. The lighting module may be an LED lighting module.

[0092] Although the present disclosure has been described in language specific to structural features and / or method acts, it is to be understood that the disclosure defined by the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A power supply circuit, the power supply circuit comprising: Input terminals (x1-a, x1-b), the input terminals being configured to receive an input voltage; A rectifier circuit, the rectifier circuit being configured to be connected to one of the input terminals; A voltage conversion circuit, the voltage conversion circuit being configured to be connected to the rectifier circuit and output a DC voltage (Vo); A controller, the controller being configured to output a control signal to the voltage conversion circuit; A voltage detector, the voltage detector being configured to detect whether the input voltage is a DC voltage or an AC voltage and output a detection signal corresponding to the detection result; And An oscillation circuit, the oscillation circuit being configured to output an oscillation signal when the voltage detector detects a DC voltage and stop outputting the oscillation signal when the voltage detector detects an AC voltage; Wherein, the oscillation signal output by the oscillation circuit is provided to the controller to change the operating frequency of the controller.

2. The power supply circuit according to claim 1, wherein When the voltage detector detects a DC voltage, the detection signal enables the oscillation circuit, When the voltage detector detects an AC voltage, the detection signal disables the oscillation circuit.

3. The power supply circuit according to claim 1, wherein The voltage detector is connected to the output node of the rectifier circuit and detects whether the input voltage is a DC voltage or an AC voltage according to the voltage at the output node.

4. The power supply circuit according to claim 3, wherein The voltage detector includes: A first switch (M60); A first resistor (R64) and a first capacitor (C64), the first resistor and the first capacitor being connected in parallel between the output node of the rectifier circuit and the control terminal of the first switch (M60); and A second resistor (R63) and a second capacitor (C49), the second resistor and the second capacitor being connected in parallel between the control terminal of the first switch (M60) and the ground terminal (GND); The first terminal of the first switch is connected to the ground terminal, and the second terminal of the first switch is connected to the oscillation circuit.

5. The power supply circuit according to claim 4, wherein The voltage detector further includes: A first diode (D22), the anode of the first diode being connected to the first connection node of the first resistor (R64) and the first capacitor (C64), and the cathode of the first diode being connected to the second connection node of the second resistor (R63) and the second capacitor (C49).

6. The power supply circuit according to claim 5, wherein The voltage detector further includes: A second diode (D23), the anode of the second diode being connected to the ground terminal, and the cathode of the second diode being connected to the first connection node of the first resistor (R64) and the first capacitor (C64).

7. The power supply circuit according to claim 4, wherein The oscillation circuit includes: A self-excited oscillator that outputs a rectangular wave from an output terminal.

8. The power supply circuit according to claim 7, wherein the oscillation circuit further includes: a third resistor (R58) and a third capacitor (C47), the third resistor and the third capacitor being connected in series between the output terminal and the ground terminal.

9. The power supply circuit according to claim 7, wherein a third connection node of the third resistor (R58) and the third capacitor (C47) is connected to the voltage detector to receive the detection signal.

10. A lighting device, the lighting device comprising a lighting module and a power supply circuit according to any one of claims 1 to 9, wherein, The power supply circuit is connected to the lighting module and supplies a DC voltage to the lighting module.

11. A control method for a power supply circuit, the method comprising: rectifying an input voltage; detecting whether the input voltage is a DC voltage or an AC voltage and outputting a detection signal corresponding to the detection result; generating an oscillation signal when the voltage detector detects a DC voltage and stopping outputting the oscillation signal when the voltage detector detects an AC voltage; outputting a control signal according to the oscillation signal; and converting the rectified voltage into an output voltage.

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