Power supply circuit and lamp

Abstract

The invention provides a power supply circuit and a lamp. The power supply circuit comprises an input port, an output port, a power factor correction module and a ballast detection module. The input port is connected with a power supply; the output port is connected with a load; two ends of the PFC module are respectively connected with the input port and the output port; the ballast detection module is connected with the PFC module, the PFC module is turned off to enable the PFC module not to work when the ballast detection module detects that the ballast is connected, and the PFC module is turned on to enable the PFC module to work when the ballast detection module detects that the ballast is not connected; when the ballast is connected, damage to the PFC module caused by high voltage generated when the ballast is started can be avoided by turning off the PFC module, and power consumption of the PFC module can be reduced.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of lamp power supply, and in particular, to a power supply circuit and a lamp. Background Art

[0002] In the lamp application environment, the access methods of lamps mainly include directly accessing the mains power and accessing the mains power through a ballast. When the power supply circuit of the lamp is connected to the ballast, the ballast will generate a high voltage during startup, and the high voltage generated by the ballast is likely to damage the power factor correction (PFC) circuit. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of the claims.

[0004] The purpose of the present application is to solve at least to a certain extent one of the technical problems existing in the related art. Embodiments of the present application provide a power supply circuit and a lamp, which can reduce the damage to the PFC circuit caused by the high voltage generated by the ballast.

[0005] In an embodiment of the first aspect of the present application, a power supply circuit includes:

[0006] An input port for connecting to a power source;

[0007] An output port for connecting to a load;

[0008] A power factor correction (PFC) module, with both ends of the PFC module connected to the input port and the output port respectively;

[0009] A ballast detection module connected to the PFC module. The ballast detection module is configured to turn off the PFC module to make the PFC module in a non-operating state when it detects that the power supply circuit is connected to a ballast, and turn on the PFC module to make the PFC module in an operating state when it detects that the power supply circuit is not connected to a ballast.

[0010] According to certain embodiments of the first aspect of the present application, the ballast detection module includes a filtering unit and a first comparison unit; both ends of the filtering unit are connected to the input port and the first comparison unit respectively; the filtering unit is configured to filter the input electrical signal of the input port to obtain a filtered electrical signal; the first comparison unit is configured to compare the numerical relationship between the filtered electrical signal and the input electrical signal to obtain a first comparison signal, and the first comparison signal is used to indicate whether the power supply circuit is connected to a ballast.

[0011] According to some embodiments of the first aspect of the present application, the ballast detection module includes a first peak detection unit, an integration unit, and a second comparison unit; both ends of the first peak detection unit are respectively connected to the input port and the second comparison unit, and both ends of the integration unit are respectively connected to the input port and the second comparison unit; the peak detection unit is used to detect the first peak of the input electrical signal at the input port, and the integration unit is used to integrate the input electrical signal at the input port to obtain a first integration value; the second comparison unit is used to compare the numerical relationship between the first peak and the first integration value to obtain a second comparison signal, and the second comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

[0012] According to some embodiments of the first aspect of the present application, the ballast detection module includes a first calculation unit and a third comparison unit; the first calculation unit is used to perform Fourier calculation on the sampling signal of the input electrical signal at the detection input port to obtain a harmonic content ratio value, and the third comparison unit is used to compare the numerical relationship between the harmonic content ratio value and a preset first threshold to obtain a third comparison signal, and the third comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

[0013] According to some embodiments of the first aspect of the present application, the ballast detection module includes a second peak detection unit, a timing unit, and a fourth comparison unit. The second peak detection unit is used to detect the second peak of the input electrical signal at the input port, the timing unit is used to calculate the duration of the second peak, and the fourth comparison unit is used to compare the numerical relationship between the duration and a preset second threshold to obtain a fourth comparison signal, and the fourth comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

[0014] According to some embodiments of the first aspect of the present application, the output end of the ballast detection module is connected to the power input end of the PFC module; when it is detected that a ballast is connected to the power supply circuit, the output end of the ballast detection module outputs a first control level to control the PFC module to turn off the PFC module.

[0015] According to some embodiments of the first aspect of the present application, the output end of the ballast detection module is connected to the feedback end of the PFC module; when it is detected that a ballast is connected to the power supply circuit, the output end of the ballast detection module outputs a second control level to change the voltage at the feedback end of the PFC module to turn off the PFC module.

[0016] According to some embodiments of the first aspect of the present application, the ballast detection module includes a timing unit, and the timing unit is connected to the PFC module; the timing unit is configured to output a startup timing signal in response to receiving a power-on signal, and the startup timing signal is used to control the startup time of the PFC module.

[0017] According to some embodiments of the first aspect of the present application, the PFC module is provided with a buffer capacitor, and the buffer capacitor is used to clamp the voltage output by the ballast when the power supply circuit is connected to the ballast.

[0018] An embodiment of the second aspect of the present application, a lighting fixture includes a light source and a power supply circuit as described in the embodiments of the first aspect of the present application, and the light source is connected to the output port of the power supply circuit.

[0019] The above solution has at least the following beneficial effects: when the ballast detection module detects that the power supply circuit is connected to the ballast, the PFC module is turned off, so that the PFC module does not work; when it detects that the power supply circuit is not connected to the ballast, the PFC module is turned on, so that the PFC module works; when the ballast is connected, turning off the PFC module can avoid damage to the PFC module caused by the high voltage generated by the ballast during startup, and can reduce the loss of the PFC module. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solutions of the present application, and do not constitute a limitation to the technical solutions of the present application.

[0021] Figure 1 It is a connection diagram of the power supply circuit with the power supply, the ballast, and the load;

[0022] Figure 2 It is a connection diagram of the power supply circuit with the power supply and the load;

[0023] Figure 3 It is a structural diagram of the power supply circuit;

[0024] Figure 4 It is a circuit diagram of the ballast detection module including a filtering unit and a first comparison unit;

[0025] Figure 5 It is a circuit diagram of the ballast detection module including a first peak detection unit, an integration unit, and a second comparison unit;

[0026] Figure 6 It is a structural diagram of the first calculation unit and the third comparison unit;

[0027] Figure 7It is a structural diagram of a second peak detection unit, a timing unit, and a fourth comparison unit;

[0028] Figure 8 It is a circuit diagram of a ballast detection module including a microcontroller;

[0029] Figure 9 It is a circuit diagram of a ballast detection module whose output terminal is connected to the power input terminal of the PFC module;

[0030] Figure 10 It is a circuit diagram of a ballast detection module whose output terminal is connected to the feedback terminal of the PFC module;

[0031] Figure 11 It is a structural diagram of the timing unit of the ballast detection module and the PFC module;

[0032] Figure 12 It is a structural diagram of a lamp; Specific embodiments

[0033] In order to make the purpose, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] It should be noted that although functional module division is performed in the device schematic diagram and the logical sequence is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from the module division in the device or the sequence in the flowchart. Terms such as "first" and "second" in the description, claims, or the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0035] Embodiments of the present application provide a power supply circuit and a lamp.

[0036] The following further elaborates on the embodiments of the present application with reference to the accompanying drawings.

[0037] Embodiments of the present application provide a power supply circuit and a lamp.

[0038] The following further elaborates on the embodiments of the present application with reference to the accompanying drawings.

[0039] Referring to Figure 1 and Figure 2 , the power supply circuit 200 includes: an input port 210, an output port 240, a power factor correction PFC module 230, and a ballast detection module 220.

[0040] Among them, the input port 210 is used to connect to the power supply 110; the output port 240 is used to connect to the load 130; both ends of the PFC module 230 are respectively connected to the input port 210 and the output port 240; the ballast detection module 220 is connected to the PFC module 230. The ballast detection module 220 is used to turn off the PFC module 230 to make the PFC module 230 in a non-operating state when it detects that the ballast 120 is connected to the power supply circuit 200, and turn on the PFC module 230 to make the PFC module 230 in an operating state when it detects that the ballast 120 is not connected to the power supply circuit 200.

[0041] Figure 1 FIG. is a schematic diagram of the power supply circuit 200 connected with the ballast 120. The input port 210 of the power supply circuit is connected to the power supply 110 through the ballast 120. Figure 2 FIG. is a schematic diagram of the power supply circuit 200 without the ballast 120 connected. The input port 210 of the power supply circuit is directly connected to the power supply 110.

[0042] It can be understood that the power supply 110 is generally the commercial power.

[0043] The ballast detection module 220 detects whether the ballast 120 is connected to the power supply circuit 200 to determine whether to make the PFC module 230 work. When the ballast 120 is connected to the power supply circuit 200, the PFC module 230 does not substantially help the power factor correction of the circuit itself. At this time, turning off the PFC module 230 can avoid the high voltage generated by the ballast 120 during startup from damaging the PFC module 230, and can reduce the loss of the PFC module 230.

[0044] Refer to Figure 3 , the PFC module 230 includes a PFC controller 231, an inductor L1, a diode D2, a buffer capacitor EC1, and a field effect transistor Q1.

[0045] The input end of the rectification circuit 211 is connected to the power supply 110. One output end 1011 of the rectification circuit 211 is connected to one input end 2011 of the ballast detection module 220, and the other output end 1012 of the rectification circuit 211 is connected to the other input end 2012 of the ballast detection module 220. One output end 2013 of the ballast detection module 220 is connected to one input end of the PFC controller 231. The other input end 3011 of the PFC controller 231 is connected to the other input end of the ballast detection module 220. The output end of the PFC controller 231 is connected to the gate of the field effect transistor Q1. One output end 1011 of the rectification circuit 211 and one input end 2011 of the ballast detection module 220 are connected to one end of the inductor L1. The other end of the inductor L1 is connected to the drain of the field effect transistor Q1 and the positive electrode of the diode D2. The negative electrode of the diode D2 is connected to one end of the buffer capacitor EC1 and one input end of the constant current circuit 241. One output end 1011 of the rectification circuit 211 is connected to the source of the field effect transistor Q1, the other end of the buffer capacitor EC1, and the other input end of the constant current circuit 241. The output end of the constant current circuit 241 is connected to the load 130.

[0046] It can be understood that when the PFC module 230 is in the non-operating state, it means that the switching element Q1 is always in the off state and not in the switching state, so no current flows through it. When the PFC module 230 is in the operating state, it means that the switching element Q1 is in the state of being able to be turned on and off, and high-frequency DC components will flow through it.

[0047] The input port 210 is generally the L and N lines of the power supply or the output end of the ballast. The input port 210 is connected to the rectification circuit 211, and the rectification circuit 211 is used to convert alternating current into direct current. Specifically, the rectification circuit 211 is a rectifier bridge formed by connecting the positive and negative electrodes of four diodes end to end. The mains power is connected through the rectifier bridge to convert the alternating current of the mains power into direct current.

[0048] The output port 240 is generally connected to an LED or other load. The output port 240 is connected to the dimming circuit. The dimming circuit adjusts the brightness of the light source by changing the voltage and current of the power supply 110 or by using PWM and other methods to meet different lighting requirements. When the user does not need full-brightness lighting, the energy consumption is reduced by reducing the brightness of the light source to achieve the purpose of energy saving. The output port 240 is connected to the constant current circuit 241, and the current output to the lamp is stabilized through the constant current circuit 241.

[0049] In a specific embodiment, the ballast detection module 220 includes a filtering unit 2211 and a first comparison unit U4; both ends of the filtering unit 2211 are respectively connected to the input port 210 and the first comparison unit U4; the filtering unit 2211 is configured to filter the input electrical signal of the input port 210 to obtain a filtered electrical signal; the first comparison unit U4 is configured to compare the numerical relationship between the filtered electrical signal and the input electrical signal to obtain a first comparison signal, and the first comparison signal is used to indicate whether a ballast 120 is connected to the power supply circuit 200.

[0050] Exemplarily, referring to Figure 4 , the input end of the filtering unit 2211 is connected to the input port 210, the output end of the filtering unit 2211 is connected to the positive input end of the harmonic amplifier U3, the harmonic amplifier U3 is used to amplify the filtered electrical signal output by the filtering unit 2211, and the negative input end of the harmonic amplifier U3 is connected to the output end of the harmonic amplifier U3.

[0051] Specifically, the filtering unit 2211 is a twin-T band-stop filter composed of a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a ninth resistor R9, and a tenth resistor R10. The operational amplifier U3 performs a follower amplification on the filtered electrical signal filtered by the filtering unit 2211. By designing the parameters of the capacitors and resistors of the filtering unit 2211, the filtering unit 2211 can filter out the fundamental wave signals from 100 Hz to 120 Hz. Since the voltage or current after connecting the ballast 120 contains a large number of high-order harmonics, when the power supply circuit 200 is connected with the ballast 120, the filtering unit 2211 filters out the fundamental wave signals, so that the filtered electrical signal filtered by the filtering unit 2211 is a signal basically containing high-order harmonics. By detecting the ratio of the signals before and after filtering by the first comparison unit U4, it can be determined whether the ballast 120 is connected to the power supply circuit 200.

[0052] When the ratio threshold of the filtered electrical signal is greater than the input electrical signal, it is determined that the ballast 120 is connected in the power supply circuit 200, otherwise it is determined that the ballast 120 is not connected in the power supply circuit 200. After the input port 210 is connected to the municipal power through the ballast 120, the input electrical signal output by the input port 210 passes through the waveform output by the ballast 120 and contains a large number of high-order harmonics. The ratio threshold can be set to 10% of the fundamental wave. Taking whether the filtered electrical signal basically containing high-order filtering is greater than 10% of the fundamental wave as the judgment criterion, it can be quickly determined whether the ballast 120 is connected to the power supply circuit 200. When the filtered electrical signal is greater than 10% of the input electrical signal, a first comparison signal indicating that the ballast 120 is connected to the power supply circuit 200 is obtained; when the filtered electrical signal is less than or equal to 10% of the input electrical signal, a first comparison signal indicating that the ballast 120 is not connected to the power supply circuit 200 is obtained.

[0053] In a specific embodiment, the ballast detection module 220 includes a first peak detection unit 2222, an integration unit 2221, and a second comparison unit U2. The two ends of the first peak detection unit 2222 are respectively connected to the input port 210 and the second comparison unit U2, and the two ends of the integration unit 2221 are respectively connected to the input port 210 and the second comparison unit U2. The peak detection unit is used to detect the first peak of the input electrical signal at the input port 210, and the integration unit 2221 is used to integrate the input electrical signal at the input port 210 to obtain a first integration value. The second comparison unit U2 is used to compare the numerical relationship between the first peak and the first integration value to obtain a second comparison signal, and the second comparison signal is used to indicate whether the ballast 120 is connected to the power supply circuit 200.

[0054] Exemplarily, when the first integration value is greater than 0.707 times the first peak, it is determined that the ballast 120 is connected in the power supply circuit 200, otherwise it is determined that the ballast 120 is not connected in the power supply circuit 200. Among them, for a sine wave, the form factor (the ratio of the effective value and the average value of the periodic waveform) of the sine wave is 1.1, and the crest factor (the ratio of the peak value and the effective value of the periodic waveform) of the sine wave is 1.414. For the ballast 120, the form factor of its output waveform is required to be less than 2.2, generally about 1.5. Due to the constant current function of the ballast 120, its peak voltage is generally less than 1.414 times the effective value. That is, after the ballast 120 is connected, the ratio of the effective value to the peak value of the output waveform is greater than 0.707. Therefore, 0.707 is used as the criterion for judging whether the ballast 120 is connected.

[0055] Referring to Figure 5 , the integration unit 2221 includes an AD637 chip U1, and integration is performed through the AD637 chip U1. The VIN pin of the AD637 chip U1 is connected to the power supply 110 through the sixteenth resistor R16 for collecting the signal of the power supply 110. At the same time, a first capacitor C1 is also connected between the VIN pin and the -VS pin of the AD637 chip U1. The signal output end of the AD637 chip U1 is connected to the positive input end of the second comparison unit U2 and outputs the first integration value of the input electrical signal at the input port 210 to the second comparison unit U2. In other embodiments, the integration unit 2221 may also adopt other circuits or other models of chips with integration calculation functions.

[0056] The output terminal of the input port 210 is connected to the first peak detection unit 2222. The first peak detection unit 2222 is composed of a first diode D1 and a sixth capacitor C6. The positive electrode of the first diode D1 is connected to the output terminal of the input port 210. The negative electrode of the first diode D1 is respectively connected to one end of the sixth capacitor C6 and the inverting input terminal of the second comparison unit U2. The other end of the sixth capacitor C6 is grounded. The first peak detection unit 2222 outputs the first peak of the input electrical signal of the input port 210 to the second comparison unit U2.

[0057] The non-inverting input terminal of the second comparison unit U2 receives the first integral value of the input electrical signal of the input port 210, and its inverting input terminal receives the first peak of the input electrical signal of the input port 210. The second comparison unit U2 compares the two signals to determine whether the first integral value of the input electrical signal is greater than 0.707 times the first peak of the input electrical signal of the input port 210, and further determines whether a ballast 120 is connected to the output terminal of the power supply 110. Specifically, when the first integral value is greater than 0.707 times the first peak, a second comparison signal indicating that the power supply circuit 200 is connected to the ballast 120 is obtained; when the first integral value is less than or equal to 0.707 times the first peak, a second comparison signal indicating that the power supply circuit 200 is not connected to the ballast 120 is obtained.

[0058] In a specific embodiment, referring to Figure 6 , the ballast detection module 220 includes a first calculation unit 2231 and a third comparison unit 2232. The first calculation unit 2231 is used to perform a Fourier calculation on the sampling signal of the input electrical signal of the detection input port 210 to obtain a harmonic content ratio value. The third comparison unit 2232 is used to compare the numerical relationship between the harmonic content ratio value and a preset first threshold to obtain a third comparison signal, and the third comparison signal is used to indicate whether a ballast 120 is connected to the power supply circuit 200.

[0059] Exemplarily, a sampling signal is obtained by sampling the input electrical signal of the input port 210 through a sampling circuit. The first calculation unit 2231 performs a Fourier calculation on the sampling signal of the input electrical signal of the detection input port 210 to obtain a harmonic content ratio value. The third comparison unit 2232 compares the numerical relationship between the harmonic content ratio value and a preset first threshold. The first threshold is set to 10%. When the harmonic content ratio value is greater than 10%, a third comparison signal indicating that the power supply circuit 200 is connected to the ballast 120 is obtained. When the harmonic content ratio value is less than or equal to 10%, a third comparison signal indicating that the power supply circuit 200 is not connected to the ballast 120 is obtained.

[0060] In a specific embodiment, referring to Figure 7, the ballast detection module 220 includes a second peak detection unit 2241, a timing unit 2242, and a fourth comparison unit 2243. The second peak detection unit 2241 is used to detect the second peak of the input electrical signal at the input port 210. The timing unit 2242 is used to calculate the duration of the second peak. The fourth comparison unit 2243 is used to compare the numerical relationship between the duration and a preset second threshold to obtain a fourth comparison signal, and the fourth comparison signal is used to indicate whether the ballast 120 is connected to the power supply circuit 200.

[0061] Exemplarily, a sampling circuit samples the input electrical signal at the input port 210 to obtain a sampling signal. The second peak detection unit 2241 detects the second peak of the input electrical signal at the input port 210. The timing unit 2242 calculates the duration of the second peak. The duration of the second peak is defined as starting from when the voltage reaches 0.95 of the highest voltage and ending when the voltage drops or rises to 0.95 of the highest voltage. The fourth comparison unit 2243 compares the numerical relationship between the duration and a preset second threshold to obtain a fourth comparison signal. The second threshold is set to 2 milliseconds. When the duration is greater than 2 milliseconds, a fourth comparison signal indicating that the ballast 120 is connected to the power supply circuit 200 is obtained. When the duration is less than or equal to 2 milliseconds, a fourth comparison signal indicating that the ballast 120 is not connected to the power supply circuit 200 is obtained.

[0062] The ballast detection module 220 can be implemented by a micro control unit (MCU), such as a single-chip microcomputer, an ARM processor, or an FPGA.

[0063] Refer to Figure 8 , the micro control unit is a single-chip microcomputer U5. The single-chip microcomputer U5 includes a first pin ADC, a second pin GPIO, and a third pin GND. The first pin ADC receives the control signal generated by the ballast detection module 220 and controls the on / off of the second pin GPIO and the third pin GND according to the control signal. The second pin is connected to the PFC module 230, and the third pin GND is grounded.

[0064] The ballast detection module 220 also includes an NPN-type triode. When the ballast detection module 220 detects that the ballast 120 is connected to the power supply circuit 200, it sends a high-level signal to the base of the triode Q1, making the collector and emitter of the triode Q1 conduct, grounding the PFC unit, thereby turning off the PFC module 230 and making the PFC module 230 not work. Otherwise, it sends a low-level signal to the base of the triode Q1, turning on the PFC module 230 and making the PFC module 230 work.

[0065] Refer to Figure 9, on the one hand, the output terminal of the ballast detection module 220 is connected to the power input terminal 110 of the PFC module 230; when it is detected that the ballast 120 is connected to the power supply circuit 200, the output terminal of the ballast detection module 220 outputs a first control level to control the PFC module 230 to turn off the PFC module 230. The turn-off of the PFC module 230 is controlled by controlling the power supply of the PFC module 230, which mainly includes the triode Q101 and the triode Q102, and both the triode Q101 and the triode Q102 are NPN-type triodes; the base of the triode Q101 is connected to the detection module and receives the control signal from the detection module, the collector of the triode Q101 is connected to the base of the triode Q102, the emitter of the triode Q101 is grounded, and the triode Q101 is used to control whether the base of the triode Q102 is grounded; the base of the triode Q102 is connected to the collector of the triode Q101, the collector of the triode Q102 is connected to the power supply 110 of the PFC module 230, and the emitter of the triode Q102 is connected to the VCC pin of the chip in the PFC module 230; when the base of the triode Q101 receives a high-level signal from the detection module, the triode Q101 conducts and makes the base of the triode Q102 grounded through the triode Q101, and then the triode Q102 is cut off, so that the power supply 110 of the PFC module 230 cannot supply power to the PFC module 230 through the triode Q102, thereby realizing the turn-off of the PFC module 230.

[0066] Refer to Figure 10, on the other hand, the output end of the ballast detection module 220 is connected to the feedback end of the PFC module 230; when it is detected that the power supply circuit 200 is connected to the ballast 120, the output end of the ballast detection module 220 outputs a second control level, changing the voltage of the feedback end of the PFC module 230 to turn off the PFC module 230, so that the PFC module 230 is in a non-operating state. By changing the voltage of the feedback end of the PFC module 230, the PFC module 230 is stopped from working. The ballast detection module 220 includes a triode Q201 and a triode Q202, and both the triode Q201 and the triode Q202 are NPN-type triodes; the feedback end of the PFC module 230 is the FB pin of the chip in the PFC module 230. The base of the triode Q201 is connected to the detection module, the collector of the triode Q201 is connected to the base of the triode Q202, and the emitter of the triode Q201 is grounded; the collector of the triode Q202 is connected to the feedback end of the chip in the PFC module 230, and the emitter of the triode Q202 is connected to the feedback end of the chip in the PFC module 230; when the base of the triode Q201 receives a high-level signal from the detection module, the triode Q201 conducts, the base of the triode Q202 is grounded through the triode Q201, the triode Q202 is cut off, disconnecting the connection between the PF pin of the control chip and the feedback end, and by changing the voltage of the feedback end of the PFC module 230, the PFC module 230 is further stopped from working.

[0067] Referring to Figure 11 , the ballast detection module 220 includes a timing unit 2251, and the timing unit 2251 is connected to the PFC module 230; the timing unit 2251 is configured to output a start timing signal in response to receiving a power-on signal, and the start timing signal is used to control the start time of the PFC module 230.

[0068] Specifically, in the initial stage of power-on of the power supply circuit 200, the PFC module 230 is not working. For example, in the initial stage of power-on of the power supply circuit 200, the timing unit 2251 outputs a start timing signal, the first part of the start timing signal is a low level, and the PFC module 230 does not start when receiving the start timing signal of the low level; the second part of the start timing signal is a high level, and the PFC module 230 starts when receiving the start timing signal of the high level.

[0069] The PFC module 230 is provided with a buffer capacitor EC1, and the buffer capacitor EC1 is used to clamp the voltage output by the ballast 120 when the power supply circuit 200 is connected to the ballast 120. In the initial stage of power-on, the ballast 120 will output a relatively high voltage; the buffer capacitor EC1 absorbs the high voltage, buffers the high voltage output by the ballast 120, and reduces the damage to the PFC module 230.

[0070] An embodiment of the present application provides a lighting fixture. Referring toFigure 12 , the lamp includes a light source 300 and the power supply circuit 200 as described above, and the light source 300 is connected to the output port 240 of the power supply circuit 200.

[0071] The above is a specific description of the preferred embodiment of the present application, but the present application is not limited to the embodiments. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present application, and these equivalent deformations or substitutions are all included within the scope defined by the claims of the present application.

Claims

1. A power supply circuit, characterized in that, Comprising: An input port for connecting to a power supply; An output port for connecting to a load; A power factor correction (PFC) module, with both ends of the PFC module connected to the input port and the output port respectively; A ballast detection module connected to the PFC module. The ballast detection module is configured to turn off the PFC module to make it in a non-operating state when detecting that a ballast is connected to the power supply circuit, and turn on the PFC module to make it in an operating state when detecting that no ballast is connected to the power supply circuit.

2. The power supply circuit according to claim 1, wherein The ballast detection module includes a filtering unit and a first comparison unit; both ends of the filtering unit are connected to the input port and the first comparison unit respectively; the filtering unit is configured to filter the input electrical signal of the input port to obtain a filtered electrical signal; The first comparison unit is configured to compare the numerical relationship between the filtered electrical signal and the input electrical signal to obtain a first comparison signal, and the first comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

3. The power supply circuit according to claim 1, wherein The ballast detection module includes a first peak detection unit, an integration unit, and a second comparison unit; both ends of the first peak detection unit are connected to the input port and the second comparison unit respectively, and both ends of the integration unit are connected to the input port and the second comparison unit respectively; the peak detection unit is configured to detect the first peak of the input electrical signal of the input port, and the integration unit is configured to integrate the input electrical signal of the input port to obtain a first integration value; the second comparison unit is configured to compare the numerical relationship between the first peak and the first integration value to obtain a second comparison signal, and the second comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

4. The power supply circuit according to claim 1, wherein, The ballast detection module includes a first calculation unit and a third comparison unit; the first calculation unit is configured to perform Fourier calculation on the sampling signal of the input electrical signal of the detection input port to obtain a harmonic content ratio value, and the third comparison unit is configured to compare the numerical relationship between the harmonic content ratio value and a preset first threshold to obtain a third comparison signal, and the third comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

5. The power supply circuit according to claim 1, characterized in that, The ballast detection module includes a second peak detection unit, a timing unit, and a fourth comparison unit. The second peak detection unit is configured to detect the second peak of the input electrical signal of the input port, the timing unit is configured to calculate the duration of the second peak, and the fourth comparison unit is configured to compare the numerical relationship between the duration and a preset second threshold to obtain a fourth comparison signal, and the fourth comparison signal is used to indicate whether a ballast is connected to the power supply circuit.

6. The power supply circuit according to claim 1, characterized in that The output end of the ballast detection module is connected to the power input end of the PFC module; when detecting that a ballast is connected to the power supply circuit, the output end of the ballast detection module outputs a first control level to control the PFC module to turn off the PFC module.

7. The power supply circuit according to claim 1, wherein The output end of the ballast detection module is connected to the feedback end of the PFC module; when it is detected that a ballast is connected to the power supply circuit, the output end of the ballast detection module outputs a second control level, changing the voltage of the feedback end of the PFC module to turn off the PFC module.

8. The power supply circuit according to claim 1, characterized in that The ballast detection module includes a timing unit, and the timing unit is connected to the PFC module; the timing unit is configured to output a start timing signal in response to receiving a power-on signal, and the start timing signal is used to control the start time of the PFC module.

9. The power supply circuit according to claim 8, wherein The PFC module is provided with a buffer capacitor, and the buffer capacitor is used to clamp the voltage output by the ballast when the power supply circuit is connected with a ballast.

10. A lighting fixture, characterized in that, It includes a light source and the power supply circuit according to any one of claims 1 to 9, and the light source is connected to the output port of the power supply circuit.

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