PFC loop circuit

Abstract

The utility model discloses a PFC loop circuit, which comprises a first starting circuit, a second starting circuit and a detection switching circuit, compensation parameter resistance values are respectively preset at the first starting circuit and the second starting circuit, and the first starting circuit and the second starting circuit are connected in parallel to form a fast response starting circuit. The second starting circuit independently forms a slow response starting circuit, and the detection switching circuit is used for determining whether the high-power LED power supply works quickly or stably by detecting the voltage condition output by a power conversion circuit of the high-power LED power supply, and switching to access the quick response starting circuit when the high-power LED power supply is quickly switched, so that the high-power LED power supply works stably. When the high-power LED power supply works stably, the slow response starting circuit is switched to be connected independently; the LED master control circuit has the advantages that the response speed of the LED master control circuit is slow when the high-power LED power supply works stably, and the response speed of the LED master control circuit is fast when the high-power LED power supply is switched on and off rapidly.

Description

Technical Field

[0001] The utility model relates to a loop circuit, in particular to a PFC loop circuit. Background Art

[0002] With the rapid development of the LED industry, LED power supply technology is becoming increasingly widely used, with high-power LED power supplies increasingly being used. Existing high-power LED power supplies typically include a PFC main control circuit, a power supply detection circuit, a PCF loop circuit, a power conversion circuit, an AC input rectifier and filter circuit, and an output rectifier and filter circuit. The AC input rectifier and filter circuit rectifies and filters the AC voltage into a DC voltage to power the PFC main control circuit. The power supply detection circuit detects whether the AC input rectifier and filter circuit outputs a preset DC voltage to the PFC main control circuit. If detected, it powers the PFC loop circuit, activating the PFC loop circuit. The PFC loop circuit provides a preset compensation parameter resistance value to the PFC main control circuit. The PFC main control circuit detects the input voltage based on the PFC loop's compensation parameter resistance value and generates a corresponding control voltage to control the power conversion circuit to output a corresponding voltage to the output rectifier and filter circuit. The output rectifier and filter circuit rectifies and filters the output voltage of the power conversion circuit to generate a DC current to drive an external LED load.

[0003] When the AC input rectifier and filter circuit is connected to an AC voltage, the AC input rectifier and filter circuit rectifies and filters the AC voltage into a DC voltage and outputs it to the PFC main control circuit. At the same time, the power supply detection circuit detects the DC voltage and outputs a corresponding voltage to power the PFC loop circuit. The PFC loop circuit starts to work and outputs a preset compensation parameter resistance value to the PFC main control circuit. The PFC main control circuit starts to operate normally, performs input voltage detection based on the compensation parameter resistance value, and generates a corresponding control voltage to control the power conversion circuit to output a corresponding voltage to the output rectifier and filter circuit. The output rectifier and filter circuit rectifies and filters the voltage output by the power conversion circuit to obtain a DC current to drive the external LED load.

[0004] Existing PFC loop circuits are divided into two types according to the size of their preset compensation parameter resistance values: slow response PFC loop circuits and fast response PFC loop circuits. The preset compensation parameter resistance value of the slow response PFC loop circuit is larger, and the preset compensation parameter resistance value of the fast response PFC loop circuit is smaller.

[0005] When a slow-response PFC loop circuit is used in a high-power LED power supply, due to the large preset compensation parameter resistance value, the input voltage detected by the PFC main control circuit is small, and the input voltage is difficult to identify. The PFC main control circuit responds slowly. Although the output voltage of the power conversion circuit is stable and the temperature of the LED main control circuit is low when the high-power LED power supply is working stably, the response speed of the PFC main control circuit cannot keep up with the rapid switching action of the high-power LED power supply when the high-power LED power supply is switched on and off quickly, which will cause significant voltage fluctuations at the output of the power conversion circuit.

[0006] When a fast-response PFC loop circuit is used in a high-power LED power supply, due to the small preset compensation parameter resistance value, the input voltage detected by the PFC main control circuit is large and easy to identify, and the PFC main control circuit responds quickly. Although the response speed of the PFC main control circuit can keep up with the fast switching action of the high-power LED power supply when the high-power LED power supply is switched on and off quickly, and the output voltage of the power conversion circuit is stable (fluctuations can be ignored), when the high-power LED is working stably, the temperature of the PFC main control circuit with a fast response speed will be high. Utility Model Content

[0007] The technical problem to be solved by the present invention is to provide a PFC loop circuit which can make the LED main control circuit respond slowly when the high-power LED power supply is working stably, and can also make the LED main control circuit respond quickly when the high-power LED power supply is switching quickly.

[0008] The present invention solves the above-mentioned technical problem by adopting a technical solution: a PFC loop circuit, comprising a first startup circuit, a second startup circuit, and a detection switching circuit. The first startup circuit and the second startup circuit are respectively preset with compensation parameter resistance values. The first startup circuit and the second startup circuit are connected in parallel to form a fast-response startup circuit, and the second startup circuit alone forms a slow-response startup circuit. The detection switching circuit is used to determine whether the high-power LED power supply is fast switching or stable operation by detecting the voltage output by the power conversion circuit of the high-power LED power supply. When the high-power LED power supply is fast switching, the fast-response startup circuit is switched to be connected. At this time, the compensation parameter resistance value output by the PFC loop circuit is the compensation parameter resistance value generated by the fast-response startup circuit. When the high-power LED power supply is stable, the slow-response startup circuit is switched to be connected alone. At this time, the compensation parameter resistance value output by the PFC loop circuit is the compensation parameter resistance value preset by the second startup circuit.

[0009] The detection switching circuit includes a MOS transistor, a diode, a first capacitor, a second capacitor, a first resistor, a second resistor, and a third resistor. One end of the first resistor, one end of the first capacitor, one end of the second capacitor, and one end of the third resistor are all grounded. The other end of the first resistor, the other end of the first capacitor, one end of the second resistor, the anode of the first diode, and the gate of the MOS transistor are connected. The drain of the MOS transistor is connected to the operating voltage output by the power supply detection circuit of the high-power LED power supply. The drain of the MOS transistor is the first output end of the detection switching circuit, and the source of the MOS transistor is the second output end of the detection switching circuit. The first output end and the second output end of the detection switching circuit output a signal for switching to the fast response startup circuit or the slow response startup circuit. The cathode of the diode, the other end of the second resistor, the other end of the second capacitor, and the other end of the third resistor are connected, and their connection end serves as the detection end of the detection switching circuit. The detection end of the detection switching circuit is used to be connected to the power conversion circuit of the high-power LED power supply to detect the voltage output by the power conversion circuit of the high-power LED power supply.

[0010] The first startup circuit includes a third capacitor, a fourth resistor and a fifth resistor, one end of the fourth resistor is the first output end of the first startup circuit, the other end of the fourth resistor is connected to one end of the third capacitor, and its connection end is the input end of the first startup circuit, the other end of the third capacitor is connected to one end of the fifth resistor, and the other end of the fifth resistor is the second output end of the first startup circuit, the first output end and the second output end of the first startup circuit are used to be connected to the PFC main control module, the first output end of the first startup circuit is connected to the first output end of the detection switching circuit, and the input end of the first startup circuit is connected to the second output end of the detection switching circuit.

[0011] The second startup circuit includes a fourth capacitor, a fifth capacitor and a sixth resistor, one end of the fifth capacitor is connected to one end of the sixth resistor, and the connection end thereof is the first output end of the second startup circuit, the other end of the sixth resistor is connected to one end of the fourth capacitor, the other end of the fourth capacitor is connected to the other end of the fifth capacitor, and the connection end thereof is the second output end of the second startup circuit, the first output end of the second startup circuit is connected to the first output end of the detection switching circuit, the second output end of the second startup circuit is connected to the second output end of the first startup circuit, and the first output end and the second output end of the second startup circuit are used to be connected to the PFC main control module.

[0012] Compared with the prior art, the advantage of the present invention is that a PFC loop circuit is constructed by the first startup circuit, the second startup circuit and the detection switching circuit. Because when the high-power LED power supply is switched on and off quickly, the voltage output by the power conversion circuit of the high-power LED power supply will jump accordingly. When the high-power LED power supply is working stably, the voltage output by the power conversion circuit of the high-power LED power supply is stable. Therefore, the voltage output by the power conversion circuit of the high-power LED power supply can be detected by the detection switching circuit to judge whether the high-power LED power supply is switched on and off quickly and whether the high-power LED power supply is working stably. Therefore, when the high-power LED power supply is switched on and off quickly, the fast-response startup circuit formed by connecting the first startup circuit and the second startup circuit in parallel can be connected. At this time, the compensation parameter resistance value connected to the LED main control circuit of the high-power LED power supply is small, and the high-power LED power supply is stable. The LED main control circuit has a relatively fast response speed and can keep up with the rapid switching action of the high-power LED power supply, so that the voltage output by the power conversion circuit is stable (fluctuations can be ignored). When the high-power LED power supply is operating stably, the slow-response startup circuit independently formed by the second startup circuit is connected. At this time, the compensation parameter resistance value connected to the LED main control circuit of the high-power LED power supply is relatively large, and the PFC main control circuit of the high-power LED power supply has a relatively slow response speed and a relatively low temperature. Therefore, the PFC loop circuit of the utility model can not only make the LED main control circuit respond slowly when the high-power LED power supply is operating stably, but also make the LED main control circuit respond quickly when the high-power LED power supply is switching rapidly, thereby ensuring the stability of the voltage output by the power conversion circuit and the relatively low temperature of the LED main control circuit during the operation of the high-power LED power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a circuit diagram of a PFC loop circuit of the utility model; DETAILED DESCRIPTION

[0014] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0015] Embodiment 1: A PFC loop circuit includes a first startup circuit, a second startup circuit, and a detection switching circuit. Compensation parameter resistance values are preset at the first startup circuit and the second startup circuit, respectively. The first startup circuit and the second startup circuit are connected in parallel to form a fast-response startup circuit, and the second startup circuit alone forms a slow-response startup circuit. The detection switching circuit is configured to determine whether the high-power LED power supply is fast switching or stable operation by detecting a voltage output by a power conversion circuit of the high-power LED power supply. When the high-power LED power supply is fast switching, the detection switching circuit switches to connecting the fast-response startup circuit. At this time, the compensation parameter resistance value output by the PFC loop circuit is the compensation parameter resistance value generated by the fast-response startup circuit. When the high-power LED power supply is stable operation, the detection switching circuit switches to connecting the slow-response startup circuit alone. At this time, the compensation parameter resistance value output by the PFC loop circuit is the compensation parameter resistance value preset at the second startup circuit.

[0016] In this embodiment, a PFC loop circuit is constructed by using the first startup circuit, the second startup circuit, and the detection switching circuit. Because when the high-power LED power supply is rapidly switched on and off, the voltage output by the power conversion circuit of the high-power LED power supply will jump accordingly. When the high-power LED power supply is operating stably, the voltage output by the power conversion circuit of the high-power LED power supply is stable. Therefore, the voltage output by the power conversion circuit of the high-power LED power supply can be detected by the detection switching circuit to determine whether the high-power LED power supply is rapidly switched on and off or operating stably. Therefore, when the high-power LED power supply is rapidly switched on and off, the fast-response startup circuit formed by connecting the first startup circuit and the second startup circuit in parallel can be connected. At this time, the compensation parameter resistor value connected to the LED main control circuit of the high-power LED power supply is relatively small, and the LED main control circuit of the high-power LED power supply has It has a relatively fast response speed and can keep up with the rapid switching action of the high-power LED power supply, so that the voltage output by the power conversion circuit is stable (fluctuations can be ignored). When the high-power LED power supply is working stably, the slow-response startup circuit independently formed by the second startup circuit is connected. At this time, the compensation parameter resistance value connected to the LED main control circuit of the high-power LED power supply is relatively large, and the PFC main control circuit of the high-power LED power supply has a relatively slow response speed and a relatively low temperature. Therefore, the PFC loop circuit of the utility model can not only make the LED main control circuit respond slowly when the high-power LED power supply is working stably, but also make the LED main control circuit respond quickly when the high-power LED power supply is switching rapidly, thereby ensuring the stability of the voltage output by the power conversion circuit and the relatively low temperature of the LED main control circuit during the operation of the high-power LED power supply.

[0017] Example 2: This example is basically the same as Example 1, except that: Figure 1As shown, in this embodiment, the detection switching circuit includes a MOS transistor Q1, a diode D1, a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2 and a third resistor R3. One end of the first resistor R1, one end of the first capacitor C1, one end of the second capacitor C2 and one end of the third resistor R3 are all grounded. The other end of the first resistor R1, the other end of the first capacitor C1, one end of the second resistor R2, the anode of the first diode D1 and the gate of the MOS transistor Q1 are connected. The drain of the MOS transistor Q1 is connected to the working voltage output by the power supply detection circuit of the high-power LED power supply. The drain of Q1 is the first output end of the detection switching circuit, and the source of the MOS transistor Q1 is the second output end of the detection switching circuit. A signal indicating whether the detection switching circuit is switched to a fast response startup circuit or a slow response startup circuit is output between the first output end and the second output end of the detection switching circuit. The cathode of the diode D1, the other end of the second resistor R2, the other end of the second capacitor C2, and the other end of the third resistor R3 are connected, and the connection end serves as a detection end of the detection switching circuit. The detection end of the detection switching circuit is used to be connected to the power conversion circuit of the high-power LED power supply to detect the voltage output by the power conversion circuit of the high-power LED power supply.

[0018] In this embodiment, when the high-power LED power supply is rapidly switching, the voltage output by the power conversion circuit of the high-power LED power supply will jump accordingly. At this time, the conduction condition of the MOS transistor Q1 is met, and the MOS transistor Q1 is turned on. A signal is output between the first output terminal and the second output terminal of the detection switching circuit to switch to the fast-response startup circuit. When the high-power LED power supply is operating stably, the voltage output by the power conversion circuit of the high-power LED power supply is stable. At this time, the conduction condition of the MOS transistor Q1 is no longer met, and the MOS transistor Q1 is turned off. A signal is output between the first output terminal and the second output terminal of the detection switching circuit to switch to the slow-response startup circuit. Thus, the detection switching circuit can determine whether the high-power LED power supply is rapidly switching or operating stably by simply detecting the voltage output by the power conversion circuit of the high-power LED power supply. Based on the determination result, the fast-response startup circuit and the slow-response startup circuit are switched to, switching to the fast-response startup circuit when the high-power LED power supply is rapidly switching and switching to the slow-response startup circuit when the high-power LED power supply is operating stably. Thus, the detection switching circuit of this embodiment achieves high-power LED power supply state detection and switching between the fast-response startup circuit and the slow-response startup circuit using a simple circuit structure, resulting in low cost and high reliability.

[0019] Example 3: This example is basically the same as Example 2, except that: Figure 1As shown, in this embodiment, the first startup circuit includes a third capacitor C3, a fourth resistor R4 and a fifth resistor R5, one end of the fourth resistor R4 is the first output end of the first startup circuit, the other end of the fourth resistor R4 is connected to one end of the third capacitor C3, and its connection end is the input end of the first startup circuit, the other end of the third capacitor C3 is connected to one end of the fifth resistor R5, and the other end of the fifth resistor R5 is the second output end of the first startup circuit, the first output end and the second output end of the first startup circuit are used to be connected to the PFC main control module, the first output end of the first startup circuit is connected to the first output end of the detection switching circuit, and the input end of the first startup circuit is connected to the second output end of the detection switching circuit.

[0020] like Figure 1 As shown, in this embodiment, the second startup circuit includes a fourth capacitor C4, a fifth capacitor C5 and a sixth resistor R6, one end of the fifth capacitor C5 is connected to one end of the sixth resistor R6, and the connection end thereof is the first output end of the second startup circuit, the other end of the sixth resistor R6 is connected to one end of the fourth capacitor C4, the other end of the fourth capacitor C4 is connected to the other end of the fifth capacitor C5, and the connection end thereof is the second output end of the second startup circuit, the first output end of the second startup circuit is connected to the first output end of the detection switching circuit, the second output end of the second startup circuit is connected to the second output end of the first startup circuit, the first output end of the second startup circuit is connected to the first output end of the first startup circuit, and the second output end of the second startup circuit is connected to the second output end of the first startup circuit.

[0021] When the PFC loop circuit of this embodiment is used in a high-power LED power supply, its operating principle is as follows: when the high-power LED power supply begins rapid startup or is unloaded, the output voltage of the power conversion circuit fluctuates. At this time, the detection end of the detection switching circuit detects the fluctuating voltage, and this voltage begins to charge the second capacitor C2. Simultaneously, the voltage divider circuit formed by the second resistor R2 and the first resistor R1 also begins to charge the first capacitor C1, causing the other end of the first capacitor C1 to output a high level to the gate of the MOS transistor Q1. At this time, the MOS transistor Q1 is turned on, and a fast-response startup circuit formed by the parallel connection of a first startup circuit formed by the fifth resistor R5, the fourth resistor R4, and the third capacitor C3 and a second startup circuit formed by the fourth capacitor C4, the fifth capacitor C5, and the sixth resistor R6 is connected. The fast-response startup circuit outputs a compensation parameter resistance value formed by the parallel connection of the compensation parameter resistance value generated by the first startup circuit formed by the fifth resistor R5, the fourth resistor R4, and the third capacitor C3 and the compensation parameter resistance value generated by the second startup circuit formed by the fourth capacitor C4, the fifth capacitor C5, and the sixth resistor R6, and provides it to the PFC main control module. When the high-power LED power supply operates in a stable state, the voltage output by the power conversion circuit does not fluctuate. At this time, the detection end of the detection switching circuit cannot detect any voltage. The second capacitor C2 discharges through the third resistor R3, and the first capacitor C1 discharges through the first resistor R1. The other end of the first capacitor C1 becomes low level, and the gate of the MOS transistor Q1 is low level. At this time, the MOS is not turned on. The second startup circuit formed by the fifth capacitor C5, the fourth capacitor C4 and the sixth resistor R6 is connected, and the compensation parameter value preset in the second startup circuit is provided to the PFC main control circuit.

Claims

1. A PFC loop circuit, characterized in that The invention comprises a first startup circuit, a second startup circuit, and a detection switching circuit. Compensation parameter resistance values are preset at the first startup circuit and the second startup circuit, respectively. The first startup circuit and the second startup circuit are connected in parallel to form a fast-response startup circuit, and the second startup circuit alone forms a slow-response startup circuit. The detection switching circuit is used to determine whether the high-power LED power supply is fast switching or stable operation by detecting the voltage output by the power conversion circuit of the high-power LED power supply. When the high-power LED power supply is fast switching, the detection switching circuit switches to connecting the fast-response startup circuit. At this time, the compensation parameter resistance value output by the PFC loop circuit is the compensation parameter resistance value generated by the fast-response startup circuit. When the high-power LED power supply is stable, the detection switching circuit switches to connecting the slow-response startup circuit alone. At this time, the compensation parameter resistance value output by the PFC loop circuit is the compensation parameter resistance value preset at the second startup circuit.

2. A PFC loop circuit according to claim 1, characterized in that The detection switching circuit includes a MOS transistor, a diode, a first capacitor, a second capacitor, a first resistor, a second resistor, and a third resistor. One end of the first resistor, one end of the first capacitor, one end of the second capacitor, and one end of the third resistor are all grounded. The other end of the first resistor, the other end of the first capacitor, one end of the second resistor, the anode of the first diode, and the gate of the MOS transistor are connected. The drain of the MOS transistor is connected to the operating voltage output by the power supply detection circuit of the high-power LED power supply. The drain of the MOS transistor is the first output end of the detection switching circuit, and the source of the MOS transistor is the second output end of the detection switching circuit. The first output end and the second output end of the detection switching circuit output a signal for switching to the fast response startup circuit or the slow response startup circuit. The cathode of the diode, the other end of the second resistor, the other end of the second capacitor, and the other end of the third resistor are connected, and their connection end serves as the detection end of the detection switching circuit. The detection end of the detection switching circuit is used to be connected to the power conversion circuit of the high-power LED power supply to detect the voltage output by the power conversion circuit of the high-power LED power supply.

3. A PFC loop circuit according to claim 2, characterized in that The first startup circuit includes a third capacitor, a fourth resistor and a fifth resistor, one end of the fourth resistor is the first output end of the first startup circuit, the other end of the fourth resistor is connected to one end of the third capacitor, and its connection end is the input end of the first startup circuit, the other end of the third capacitor is connected to one end of the fifth resistor, and the other end of the fifth resistor is the second output end of the first startup circuit, the first output end and the second output end of the first startup circuit are used to be connected to the PFC main control module, the first output end of the first startup circuit is connected to the first output end of the detection switching circuit, and the input end of the first startup circuit is connected to the second output end of the detection switching circuit.

4. A PFC loop circuit according to claim 3, characterized in that The second startup circuit includes a fourth capacitor, a fifth capacitor and a sixth resistor, one end of the fifth capacitor is connected to one end of the sixth resistor, and the connection end thereof is the first output end of the second startup circuit, the other end of the sixth resistor is connected to one end of the fourth capacitor, the other end of the fourth capacitor is connected to the other end of the fifth capacitor, and the connection end thereof is the second output end of the second startup circuit, the first output end of the second startup circuit is connected to the first output end of the detection switching circuit, the second output end of the second startup circuit is connected to the second output end of the first startup circuit, and the first output end and the second output end of the second startup circuit are used to be connected to the PFC main control module.

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