A dimming power supply

Abstract

This invention discloses a dimming power supply, comprising a rectifier input filter unit, a flyback control unit, an isolation transformer unit, and a dimming unit arranged sequentially. The flyback control unit includes an on-time setting terminal for setting the on-time of the thyristor in the dimmer. The on-time adjustment unit includes a first resistor unit, a switch unit, and a second resistor unit. When the switch unit is open, the second resistor unit is in an open-circuit state, and the on-time is determined by the resistance value of the first resistor unit. When the switch unit is on, the second resistor unit is connected in parallel with the first resistor unit, and the on-time is determined by the resistance value of the first and second resistor units connected in parallel. By changing the conduction state of the switch unit when the actual on-time of the thyristor in the dimmer is inconsistent with the set on-time, the on-time of the thyristor in the dimmer can be adjusted, resulting in a deeper dimming depth.

Description

Technical Field

[0001] This invention relates to the field of thyristor dimming control technology, and in particular to a dimming power supply. Background Technology

[0002] SCR dimming is a technology that adjusts the output current by changing the conduction angle of a SCR, thereby controlling the brightness of an LED. Due to its advantages such as good dimming stability, fast response speed, and low adjustment cost, it is the most widely used dimming method compared to others. Dimming depth is a crucial indicator of SCR dimming fixtures, representing the lowest LED brightness without flicker when the conduction phase is relatively small. However, SCR dimming requires matching different dimmers, and due to the semi-controlled switch nature of the SCR, it can only turn on the current, not completely turn it off. Even at the lowest setting, a weak current still flows, resulting in a limited dimming range and a relatively poor dimming depth.

[0003] Therefore, the purpose of this application is to provide a dimming power supply that solves at least one of the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a dimming power supply that addresses the shortcomings of the aforementioned technologies.

[0005] The present invention designs a dimming power supply, including a rectifier input filter unit, a flyback control unit, an isolation transformer unit, and a dimming unit arranged in sequence. The dimming unit includes a conduction time adjustment unit electrically connected to the rectifier input filter unit, the flyback control unit, and the isolation transformer unit respectively. The flyback control unit includes a conduction time setting terminal for setting the conduction time of the thyristor in the dimmer. The conduction time adjustment unit includes a first resistor unit, a switch unit, and a second resistor unit.

[0006] The primary coil of the isolation transformer unit includes a first main winding and a first auxiliary winding. The first end of the first main winding is electrically connected to the grid side through a rectifier input filter unit. The dimmer is disposed between the grid side and the input end of the dimming power supply. The second end of the first main winding is electrically connected to the flyback control unit. The flyback control unit is electrically connected to both ends of the first auxiliary winding. The first main winding is coupled to the secondary coil. Both ends of the secondary coil are electrically connected to the load side.

[0007] A first resistor unit is provided between the on-time setting terminal and the ground terminal. After the switch unit and the second resistor unit are connected in series, one end of the switch unit is electrically connected to the first end of the first main winding, the output terminal of the rectifier input filter unit, one end of the first auxiliary winding and the ground terminal, and the other end of the switch unit is electrically connected to the on-time setting terminal.

[0008] When the switching unit is open, the second resistor unit is in an open-circuit state, and the conduction time of the thyristor is determined by the resistance value of the first resistor unit; when the switching unit is on, the second resistor unit and the first resistor unit are connected in parallel, and the conduction time of the thyristor is determined by the resistance value of the first resistor unit and the second resistor unit connected in parallel.

[0009] After the dimming power supply is started, the grid side supplies power to the flyback control unit. When the supply voltage of the flyback control unit reaches the preset voltage, the flyback control unit sends a control signal to its built-in MOSFET to turn it on. Current flows through the isolation transformer unit, causing the primary coil to store energy. When the MOSFET's on-time reaches the set duration, the flyback control unit sends a control signal to turn it off. The primary coil releases energy to its secondary coil, and the secondary coil outputs a constant current control signal to power the LED on the load side. At the same time, current flows through the first auxiliary winding, providing a stable operating voltage to the flyback control unit. When the actual on-time of the dimmer is less than the on-time set at the on-time setting terminal, the switching unit turns on, connecting the second resistor unit in parallel with the first resistor unit. At this time, the resistance value between the on-time setting terminal and the ground terminal of the flyback control unit decreases, the on-time becomes shorter, and the dimming depth becomes deeper.

[0010] Preferably, the first resistor unit includes a variable resistor, the switching unit includes a first switching transistor, a first resistor, a second resistor, and a first capacitor, and the second resistor unit includes a third resistor;

[0011] The first end of the first resistor is electrically connected to the first end of the first main winding and the output end of the rectifier input filter unit, respectively. The second end of the first resistor is electrically connected to the first end of the second resistor and the base of the first switching transistor, respectively. The second end of the second resistor is electrically connected to the collector of the first switching transistor and one end of the first auxiliary winding, respectively. The collector of the first switching transistor is electrically connected to the ground terminal. The first capacitor is connected in parallel across the two ends of the second resistor. The emitter of the first switching transistor is electrically connected to the on-time setting terminal through the third resistor. The first end of the variable resistor is electrically connected to the ground terminal, and the second end of the variable resistor is electrically connected to the on-time setting terminal.

[0012] Preferably, the dimming unit further includes a voltage smoothing unit, which includes a second capacitor and a fourth resistor connected in series. The first end of the fourth resistor is electrically connected to the output end of the rectifier input filter unit, the first end of the first resistor, and the first end of the first main winding, respectively. The second end of the second capacitor is electrically connected to the ground terminal.

[0013] Preferably, the dimming power supply further includes a ripple reduction unit, the input terminal of which is electrically connected to the secondary coil, and the output terminal of which is electrically connected to the load side.

[0014] Preferably, the dimming power supply further includes a rectifier output filter unit electrically connected to the ripple removal unit. The secondary coil of the isolation transformer unit includes a second main winding and a second auxiliary winding. The first end of the second auxiliary winding is electrically connected to the input end of the ripple removal unit, and the output end of the ripple removal unit is electrically connected to the negative terminal of the load side. The first end of the second main winding is electrically connected to the second end of the second auxiliary winding. The input end of the rectifier output filter unit is electrically connected to both ends of the second main winding. The output end of the rectifier output filter unit is electrically connected to the positive terminal of the load side. The rectifier output filter unit is electrically connected to the ripple removal unit and to the ground terminal.

[0015] Preferably, the rectifier input filter unit includes a rectifier bridge and an EMI filter unit; the input terminal of the rectifier bridge is electrically connected to the power grid side and the dimmer, respectively, and the output terminal of the rectifier bridge is electrically connected to the first terminal of the first main winding through the EMI filter unit.

[0016] Preferably, the resistance value of the first resistor unit is 20K-50K.

[0017] Preferably, the conduction time setting terminal sets the conduction time of the thyristor to 4-10ms.

[0018] The technical effect of this invention is that, when the actual on-time of the dimmer's thyristor is inconsistent with the set on-time, the on-state of the switching unit changes, allowing the second resistor unit to be selectively connected in parallel with the first resistor unit. This enables adjustment of the on-time set by the flyback control unit and adjustment of the dimming depth, resulting in a deeper dimming depth, simplifying the circuit structure, and taking into account the dimming effects of different dimmers.

[0019] By isolating high voltage and low voltage through an isolation transformer unit, the safety of the dimming power supply is improved. Compared with the conventional method of increasing line impedance to improve the dimming effect, it does not require increasing line impedance and can reduce heat generation.

[0020] By setting a voltage smoothing unit to buffer the current, voltage surges are prevented, resulting in smoother dimming. At the same time, a ripple reduction unit is set to reduce output ripple and output a low-ripple constant current signal to the load side to improve the dimming effect. Attached Figure Description

[0021] Figure 1 This is a structural principle block diagram of the dimming power supply provided by the present invention;

[0022] Figure 2 yes Figure 1 The circuit schematic diagram.

[0023] The attached figures are labeled as follows:

[0024] 1. Rectifier input filter unit; 11. Rectifier bridge; 12. EMI filter unit; 2. Flyback control unit; 3. Isolation transformer unit; 4. Dimming unit; 41. On-time adjustment unit; 411. First resistor unit; 412. Switching unit; 413. Second resistor unit; 42. Voltage smoothing unit; 5. Dimmer; 6. Ripple removal unit; 7. Rectifier output filter unit. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] Example 1

[0027] In this embodiment, as Figure 1 , 2 As shown, the present invention discloses a dimming power supply, comprising a rectifier input filter unit 1, a flyback control unit 2, an isolation transformer unit 3, and a dimming unit 4 arranged sequentially. The flyback control unit 2 has a thyristor dimming function, including an on-time setting terminal (i.e., the TONMAX pin of the flyback chip U1) for setting the on-time of the thyristor in the dimmer 5, thereby realizing thyristor dimming control. The flyback chip U1 of the flyback control unit 2 has a built-in MOSFET for high-frequency switching. The isolation transformer unit 3 uses a transformer T1 to couple high-voltage signals and isolate low-voltage output signals.

[0028] The dimming unit 4 includes a conduction time adjustment unit 41 that is electrically connected to the rectifier input filter unit 1, the flyback control unit 2, and the isolation transformer unit 3 respectively. The conduction time adjustment unit 41 includes a first resistor unit 411, a switch unit 412, and a second resistor unit 413.

[0029] The primary coil of the isolation transformer unit 3 includes a first main winding and a first auxiliary winding. The first end of the first main winding is electrically connected to the grid side through the rectifier input filter unit 1. The dimmer 5 is located between the grid side and the input end of the dimming power supply. A filter unit is also provided between the input end of the dimming power supply and the input end of the rectifier input filter unit 1.

[0030] The second end of the first main winding is electrically connected to the flyback control unit 2. The flyback control unit 2 is electrically connected to both ends of the first auxiliary winding. The first main winding is coupled to the secondary coil. Both ends of the secondary coil are electrically connected to the load side.

[0031] Among them, the load side is the lighting unit, and the dimmer 5 is a thyristor dimmer. When the input voltage is applied to the two ends of the thyristor, the effective value of the input voltage is changed by adjusting the conduction angle of the thyristor. The larger the conduction angle, the higher the effective value of the input voltage, and the brightness of the lighting unit will increase. Conversely, the smaller the conduction angle, the lower the effective value of the input voltage, and the brightness of the lighting unit will decrease.

[0032] A first resistor unit 411 is provided between the conduction time setting terminal 21 and the ground terminal. After the switch unit 412 and the second resistor unit 413 are connected in series, one end of the switch unit 412 is electrically connected to the first terminal of the first main winding, the output terminal of the rectifier input filter unit 1, one end of the first auxiliary winding, and the ground terminal, respectively, and the other end of the switch unit 412 is electrically connected to the conduction time setting terminal. When the switch unit 412 is open, the second resistor unit 413 is in an open circuit state, and the conduction time of the thyristor is determined by the resistance value of the first resistor unit 411. When the switch unit 412 is on, the second resistor unit 413 is connected in parallel with the first resistor unit 411, and the conduction time of the thyristor is determined by the resistance value of the first resistor unit 411 and the second resistor unit 413 connected in parallel.

[0033] The first resistor unit 411 includes a variable resistor R9; the switching unit 412 includes a first switching transistor Q3, a first resistor R17, a second resistor R10, and a first capacitor C7; the second resistor unit 413 includes a third resistor R5; the first end of the first resistor R17 is electrically connected to the first end of the first main winding and the output end of the rectifier input filter unit 1, respectively; the second end of the first resistor R17 is electrically connected to the first end of the second resistor and the base of the first switching transistor Q3, respectively; the second end of the second resistor R10 is electrically connected to the collector of the first switching transistor Q3 and one end of the first auxiliary winding, respectively; the collector of the first switching transistor Q3 is electrically connected to the ground terminal; the first capacitor C7 is connected in parallel across the two ends of the second resistor R10; the emitter of the first switching transistor Q3 is electrically connected to the conduction time setting terminal through the third resistor R5; the first end of the variable resistor R9 is electrically connected to the ground terminal; and the second end of the variable resistor R9 is electrically connected to the conduction time setting terminal.

[0034] When the first switch Q3 is off, the third resistor R5 is not connected to the TONMAX pin, and the conduction time of the thyristor is determined solely by the resistance value of the variable resistor R9. When the voltage at the connection point of the first resistor R17 and the second resistor R10 is below 0.6V, since the conduction voltage of the first switch Q3 is 0.6V, the first switch Q3 is on. Furthermore, in addition to the variable resistor R9, the third resistor R5 is connected in parallel to the TONMAX pin. The conduction time of the thyristor is determined by the parallel resistance value of the variable resistor R9 and the third resistor R5. Therefore, as the resistance value to ground at the TONMAX pin decreases, the conduction time of the thyristor decreases, resulting in a smaller minimum turn-off current and a deeper dimming depth.

[0035] In practical applications, because the flyback chip U1 also has internal impedance, R TONMAX The actual resistance to ground of the TONMAX pin is the sum of the internal impedance of the flyback chip U1 and the resistance to ground of the TONMAX pin. The main purpose of this invention is to provide a circuit structure that does not increase the line impedance. By adjusting the conduction time of the TONMAX pin of the flyback chip U1 in combination with the change of the conduction state of the switching unit 412, the dimming effect and dimming depth can be improved. As for the internal impedance value of the flyback chip U1, it can be obtained by conventional measurement methods, which will not be elaborated here.

[0036] To be compatible with more types of dimmers, the on-time setting terminal sets the on-time of the thyristor to 4-10ms. When the actual on-time of the thyristor of the matched dimmer 5 is greater than the set on-time, the first switch Q3 is in the off state. When the actual on-time of the thyristor of the matched dimmer 5 is less than or equal to the set on-time, the first switch Q3 is in the on state.

[0037] In this embodiment, the conduction time of the thyristor is set to 4.5ms, corresponding to a conduction angle of 81°. The thyristor conducts during the 0-81° range of the positive half-cycle of the sine wave and de-converts during the 81°-180° range of the positive half-cycle. The specific conduction time setting is determined by the user's actual requirements.

[0038] like Figure 2 As shown, the dimming unit 4 also includes a voltage smoothing unit 42. The voltage smoothing unit 42 includes a second capacitor C3 and a fourth resistor R2 connected in series. The first end of the fourth resistor R2 is electrically connected to the output end of the rectifier input filter unit 1, the first end of the first resistor R17, and the first end of the first main winding, respectively. The second end of the second capacitor C3 is electrically connected to the ground end.

[0039] When the dimming power supply is turned on, the input terminal of the rectifier input filter unit 1 is connected to the grid side. When the voltage exceeds the trigger voltage of the thyristor, the thyristor in the dimmer 5 starts to conduct, and the current flows through the fourth resistor R2 and the second capacitor C3. The second capacitor C3 starts to charge. When the second capacitor C3 is fully charged, the voltage of the voltage smoothing unit 42 reaches a stable value. When the dimming power supply is turned off, the second capacitor C3 starts to discharge, the voltage of the voltage smoothing unit 42 drops to zero, and the thyristor stops conducting.

[0040] By setting the voltage smoothing unit 42, the dimming power supply can remain in a stable state during the discharge process of the second capacitor C3, allowing the current flowing through it to gradually become zero, avoiding sudden current changes, and making the dimming smoother and the dimming effect better. The fourth resistor R2 is 470Ω, and the second capacitor C3 is 220nF, which meets the requirements of general dimmers, with low losses and good dimming effect.

[0041] Taking the MIBOXER AC Triac RF+Push dimmer Model TRI-C1 dimmer as an example, without the on-time adjustment unit 41, the dimming effect is improved by increasing the line impedance through adjusting the resistor and capacitor values ​​in the voltage smoothing unit 42. Under these conditions, where the circuit temperature allows, the minimum current for SCR dimming is 47.1mA. Since dimming depth = minimum turn-off current / maximum current, and given the maximum current, the corresponding dimming depth is 13%. However, higher impedance results in more heat generation from the SCR, affecting heat dissipation. Without increasing the circuit impedance, by setting the on-time adjustment unit 41, the minimum current for SCR dimming becomes 18mA, resulting in a dimming depth of 5%. Therefore, the on-time adjustment unit 41 deepens the dimming depth of the power supply and reduces heat generation compared to increasing the line impedance.

[0042] The dimming power supply also includes a ripple reduction unit 6. The input terminal of the ripple reduction unit 6 is electrically connected to the secondary coil, and the output terminal of the ripple reduction unit 6 is electrically connected to the load side. By controlling the conduction state of the switching transistor Q1 in the ripple reduction unit 6, the output ripple is reduced.

[0043] The dimming power supply also includes a rectifier output filter unit 7 electrically connected to the ripple removal unit 6. The secondary coil of the isolation transformer unit 3 includes a second main winding and a second auxiliary winding. The first end of the second auxiliary winding is electrically connected to the input end of the ripple removal unit 6, and the output end of the ripple removal unit 6 is electrically connected to the negative terminal of the load side. The first end of the second main winding is electrically connected to the second end of the second auxiliary winding. The input end of the rectifier output filter unit 7 is electrically connected to both ends of the second main winding. The output end of the rectifier output filter unit 7 is electrically connected to the positive terminal of the load side. The rectifier output filter unit 7 is electrically connected to the ripple removal unit 6 and to the ground terminal.

[0044] like Figure 1 , 2 As shown, the rectifier input filter unit 1 includes a rectifier bridge 11 and an EMI filter unit 12; the input terminal of the rectifier bridge 11 is electrically connected to the grid side and the dimmer 5 respectively, and the output terminal of the rectifier bridge 11 is electrically connected to the first terminal of the first main winding through the EMI filter unit 12.

[0045] In this embodiment, rectifier bridge 11 is rectifier bridge BD1, and EMI filter unit 12 includes inductor L1, inductor L3, resistor R1, resistor R21, capacitor C1, and capacitor C2. The input terminal of rectifier bridge BD1 is electrically connected to the power grid side. The two ends of inductor L1 are electrically connected to the output terminal of rectifier bridge BD1 and transformer T1, respectively. Resistor R1 is connected in parallel across inductor L1. One end of inductor L3 is electrically connected to one end of resistor R1 through capacitor C1, and the other end of inductor L3 is electrically connected to the other end of resistor R1 through capacitor C2. Resistor R21 is connected in parallel across inductor L3, and the two ends of R21 are electrically connected to ground. Rectifier bridge BD1 rectifies the input AC power and outputs high-voltage DC power. EMI filter unit 12 is used to reduce high-frequency components and remove noise and interference.

[0046] Based on the operating performance of the dimmer 5 and the operating parameters of the LED on the load side, the resistance value of the first resistor unit 411 (i.e., the variable resistor R9) is adjusted to set the conduction time of the thyristor in the dimmer 5. The resistance value of the first resistor unit 411 is 20K-50K. The flyback control unit 2 can adjust the resistance value of the first resistor unit 411 as needed to set the conduction time of the thyristor in the dimmer 5.

[0047] The AC input voltage of 230V from the grid side is rectified by the rectifier bridge BD1. Inductors L1 and L3, capacitors C1 and C2 filter the forward voltage and current. The voltage is absorbed by the second capacitor C3 and the fourth resistor R2. The high voltage DC current is current-limited by the resistor R4 and supplies power to the HV pin of the flyback chip U1 in the flyback control unit 2.

[0048] After the flyback chip U1 completes a set cycle, the flyback control unit 2 detects the voltage at the CS pin of the flyback chip U1 through the first voltage acquisition unit between the CS pin and the ground terminal. When the voltage at the CS pin of the flyback chip U1 reaches the preset voltage, the flyback control unit 2 sends a control signal to the MOSFET built into the flyback chip U1 to turn it on; otherwise, it turns off the dimming power supply. After the MOSFET is turned on, the DRAIN pin of the flyback chip U1 is turned on, and current flows through the transformer T1, causing the primary coil to store energy. At this time, the secondary coil is in a non-operating state. The first main winding of the transformer T1 is equipped with an RCD snubber circuit electrically connected to the DRAIN pin of the flyback chip U1. The RCD snubber circuit is used to absorb the LC oscillation voltage caused by the transformer leakage inductance and the MOSFET parasitic capacitance, and to suppress the DS spike voltage of the MOSFET.

[0049] When the MOSFET of flyback chip U1 has been on for a set duration, flyback control unit 2 sends a control signal to the MOSFET to turn it off. The primary coil releases energy to its secondary coil. The voltage output from the secondary coil is rectified by diode D4, filtered by capacitor CE3, and then passes through ripple reduction unit 6 to output a low-ripple constant current signal to power the load side. Simultaneously, current flows through the first auxiliary winding to provide a stable operating voltage to flyback chip U1 in flyback control unit 2. During operation, flyback chip U1 uses a second voltage acquisition unit between its OVP pin and the first auxiliary winding to detect the voltage at its OVP pin in real time, controlling the maximum voltage output of the dimming power supply to achieve overvoltage protection. When flyback chip U1 is operating normally, its operating cycle is the same as the on-time of the MOSFET in flyback chip U1.

[0050] The dimming power supply provided by this invention uses fewer components, occupies a small size, can achieve safe isolation, low ripple, smooth dimming, deeper dimming depth, and generates less heat.

[0051] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A dimming power supply, characterized by: The application relates to a dimmer, which comprises a rectifying input filter unit (1), a flyback control unit (2), an isolation transformer unit (3) and a dimming unit (4) arranged in sequence, wherein the dimming unit (4) comprises a conduction time adjusting unit (41) electrically connected with the rectifying input filter unit (1), the flyback control unit (2) and the isolation transformer unit (3) respectively, the flyback control unit (2) comprises a conduction time setting end for setting the conduction time of a thyristor in a dimmer (5), and the conduction time adjusting unit (41) comprises a first resistor unit (411), a switch unit (412) and a second resistor unit (413). The primary coil of the isolation transformer unit (3) comprises a first main winding and a first auxiliary winding, the first end of the first main winding is electrically connected with a power grid side through the rectifying input filter unit (1), the dimmer (5) is arranged between the power grid side and the input end of a dimming power supply, the second end of the first main winding is electrically connected with the flyback control unit (2), the flyback control unit (2) is electrically connected with the two ends of the first auxiliary winding, the first main winding is coupled with a secondary coil, and the two ends of the secondary coil are electrically connected with a load side. The first resistor unit (411) is arranged between the conduction time setting end and a grounding end, the switch unit (412) and the second resistor unit (413) are connected in series, one end of the switch unit (412) and the second resistor unit (413) is respectively electrically connected with the first end of the first main winding, the output end of the rectifying input filter unit (1), one end of the first auxiliary winding and the grounding end, and the other end of the switch unit (412) and the second resistor unit (413) is electrically connected with the conduction time setting end (21). When the switch unit (412) is turned off, the second resistor unit (413) is in an open circuit state, and the conduction time of the thyristor is determined by the resistance value of the first resistor unit (411); when the switch unit (412) is turned on, the second resistor unit (413) is connected in parallel with the first resistor unit (411), and the conduction time of the thyristor is determined by the resistance value of the parallel connection of the first resistor unit (411) and the second resistor unit (413). The first resistor unit (411) comprises a variable resistor, the switch unit (412) comprises a first switch tube, a first resistor, a second resistor and a first capacitor, and the second resistor unit (413) comprises a third resistor. The first end of the first resistor is respectively electrically connected with the first end of the first main winding and the output end of the rectifying input filter unit (1), the second end of the first resistor is respectively electrically connected with the first end of the second resistor and the base of the first switch tube, the second end of the second resistor is respectively electrically connected with the collector of the first switch tube and one end of the first auxiliary winding, the collector of the first switch tube is electrically connected with the grounding end, the first capacitor is connected in parallel with the two ends of the second resistor, the emitter of the first switch tube is electrically connected with the conduction time setting end through the third resistor, the first end of the variable resistor is electrically connected with the grounding end, and the second end of the variable resistor is electrically connected with the conduction time setting end.

2. The dimming power supply of claim 1, wherein: The dimming unit (4) further comprises a voltage smoothing unit (42), the voltage smoothing unit (42) comprising a second capacitor and a fourth resistor connected in series, a first end of the fourth resistor being electrically connected with an output end of the rectifier input filter unit (1), a first end of the first resistor and a first end of the first main winding respectively, and a second end of the second capacitor being electrically connected with a ground end.

3. The dimming power supply of claim 1, wherein: The dimming power supply further comprises a ripple elimination unit (6), an input end of the ripple elimination unit (6) being electrically connected with the secondary winding, and an output end of the ripple elimination unit (6) being electrically connected with a load side.

4. The dimming power supply of claim 3, wherein: The dimming power supply further comprises a rectifier output filter unit (7) electrically connected with the ripple elimination unit (6), the secondary winding of the isolation transformer unit (3) comprising a second main winding and a second auxiliary winding, a first end of the second auxiliary winding being electrically connected with an input end of the ripple elimination unit (6), an output end of the ripple elimination unit (6) being electrically connected with a negative pole of the load side, a first end of the second main winding being electrically connected with a second end of the second auxiliary winding, an input end of the rectifier output filter unit (7) being electrically connected with two ends of the second main winding, an output end of the rectifier output filter unit (7) being electrically connected with a positive pole of the load side, the rectifier output filter unit (7) being electrically connected with the ripple elimination unit (6), and the rectifier output filter unit (7) being electrically connected with a ground end.

5. A dimming power supply as claimed in any one of claims 1 to 4, characterized in that: The rectifier input filter unit (1) comprises a rectifier bridge (11) and an EMI filter unit (12), input ends of the rectifier bridge (11) being electrically connected with a power grid side and a dimmer (5) respectively, and output ends of the rectifier bridge (11) being electrically connected with a first end of the first main winding through the EMI filter unit (12).

6. The dimming power supply of claim 1, wherein: The first resistor unit (411) has a resistance value of 20K-50K.

7. The dimming power supply of claim 1, wherein: The conduction time setting end sets the conduction time of the thyristor to 4-10ms. The conduction time setting end sets the conduction time of the thyristor to 4-10ms.

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