A discrete component self-oscillating thyristor deep dimming circuit

Abstract

The present invention relates to the technical field of deep dimming circuits, and particularly to a discrete self-oscillating thyristor deep dimming circuit. The power input end is connected to the circuit through a thyristor dimmer to control the LED load light source, and includes an EMC circuit, a rectifier filter circuit, a discrete self-oscillating circuit, a ripple smoothing circuit and a deep dimming circuit; it also includes a transformer with a primary coil and a secondary coil respectively connected to the discrete self-oscillating circuit and the ripple smoothing circuit. The present invention solves the problems that the existing thyristor dimming circuit cannot achieve good dimming depth, cannot support most of the thyristor dimmers on the market, has large power frequency ripple, jitters and flickers during the dimming process, and has high costs.

Description

Technical Field

[0001] The present invention relates to the technical field of deep dimming circuits, and particularly to a discrete self-oscillating thyristor deep dimming circuit. Background Art

[0002] A dimming circuit is to adjust the brightness of an LED or a light bulb, and the implementation methods usually include: analog dimming, timer dimming, PWM pulse width dimming, and thyristor dimming, etc.

[0003] In the existing thyristor dimming circuits, problems such as inability to achieve good dimming depth, inability to support most of the thyristor dimmers on the market, large power frequency ripple, jitter and flicker during the dimming process, and high cost usually occur.

[0004] Therefore, a discrete self-oscillating thyristor deep dimming circuit has emerged as the times require. Summary of the Invention

[0005] The content of the present invention is to provide a discrete self-oscillating thyristor deep dimming circuit, which mainly solves the problems of the existing thyristor dimming circuit, such as inability to achieve good dimming depth, inability to support most of the thyristor dimmers on the market, large power frequency ripple, jitter and flicker during the dimming process, and high cost.

[0006] The present invention proposes a discrete self-oscillating thyristor deep dimming circuit. The power input terminal controls an LED load light source after being connected to the circuit through a thyristor dimmer, and includes an EMC circuit, a rectifier filter circuit, a discrete self-oscillating circuit, a ripple smoothing circuit, and a deep dimming circuit; it also includes a transformer with a primary coil and a secondary coil respectively connected to the discrete self-oscillating circuit and the ripple smoothing circuit;

[0007] The rectifier filter circuit is used to rectify the input voltage to obtain a rectified voltage;

[0008] The discrete self-oscillating circuit is used to convert the rectified voltage into a PWM voltage signal;

[0009] The ripple smoothing circuit is used to remove the input AC component;

[0010] The deep dimming circuit is used to stabilize the current oscillation flowing in the thyristor dimmer; it is also used to provide a stable dynamic load when the input voltage is a phase-cut voltage.

[0011] Preferably, the discrete self-oscillating circuit includes a resistor R2, a resistor R3, a resistor R6, a resistor R6A, a resistor RS1, a resistor RS2, a transformer T1, a triode Q1, a triode Q2, a capacitor C5, and a diode D1.

[0012] Preferably, the resistors RS1 and RS2 are connected in parallel and serve as current-limiting sampling resistors; a transformer leakage inductance discharging circuit is further provided in the discrete component self-oscillation circuit, and the transformer leakage inductance discharging circuit includes a resistor R8, a resistor R8A, a capacitor C6, and a diode D3.

[0013] Preferably, the ripple smoothing circuit includes a capacitor C9, a capacitor C10, resistors R18, R19, R20, R21, R22, diodes D11, D13, D14, zener diodes Z3, Z4, and an NMOS transistor Q5.

[0014] Preferably, the capacitor C9 and the diode D13 are connected in series and then connected to the secondary coil of the transformer, and the anode signal of the diode D13 is grounded; the anode of the capacitor C10 is connected to the resistors R21 and R20 and then connected to the cathode of the diode D4 in parallel and connected to one end of the capacitor C9; the other end of the capacitor C9 is connected to the between the resistors R20 and R21 through the resistor R19 and then through the diode D11; the cathode of the D4 is also connected in parallel with the anode of the diode D14, the resistor R24, and the drain of the NMOS transistor Q5; the cathode of the diode D14 is connected to the cathode of the zener diode Z3; the source of the NMOS transistor is connected to the anode of the zener diode Z4.

[0015] Preferably, the deep dimming circuit includes resistors R13, R14, R15, R16, R17, diodes D8, D9, a transistor Q6, and a transistor Q7.

[0016] Preferably, the transistors Q6 and Q7 form a thyristor trigger button circuit.

[0017] Preferably, a short-circuit protection circuit and an open-circuit protection circuit are further provided in parallel between the discrete component self-oscillation circuit and the LED load light source.

[0018] As can be seen from the above, the following beneficial effects can be obtained by applying the technical solution provided by the present invention:

[0019] First, a deep dimming circuit is provided in the circuit proposed by the present invention, which can be used to support a dimming depth of 1 to 100%, thereby controlling the LED load light source to achieve a larger dimming range, a smaller dimming step value, and a better dimming effect;

[0020] Second, a discrete component self-oscillation circuit is provided in the circuit proposed by the present invention, which uses discrete component devices to achieve self-excited oscillation, and the cost is lower;

[0021] Thirdly, the circuit proposed by the present invention can be adapted to up to 95% of thyristor dimmers, and can also achieve a ripple factor of less than 1% in the output, and there is no jitter or flicker during the dimming process, realizing smooth dimming. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is the actual application connection diagram of the discrete self-oscillating thyristor deep dimming circuit in the embodiment of the present invention;

[0024] Figure 2 It is the internal block diagram of the discrete self-oscillating thyristor deep dimming circuit in the embodiment of the present invention;

[0025] Figure 3 It is the specific circuit diagram of the discrete self-oscillating thyristor deep dimming circuit in the embodiment of the present invention. Detailed Embodiment

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0027] The existing thyristor dimming circuit cannot achieve good dimming depth, cannot support most of the thyristor dimmers on the market, has large power frequency ripple, jitter and flicker during the dimming process, and high cost.

[0028] As Figures 1 to 3 shown, in order to solve the above problems, this embodiment proposes a discrete self-oscillating thyristor dimming circuit. The power input terminal controls the LED load light source after being connected to the circuit through a thyristor dimmer. The circuit includes an EMC circuit, a rectifier filter circuit, a discrete self-oscillating circuit, a ripple smoothing circuit, and a deep dimming circuit; it also includes a transformer with a primary coil and a secondary coil respectively connected to the discrete self-oscillating circuit and the ripple smoothing circuit.

[0029] Among them, a rectifier filter circuit is used to rectify the input voltage to obtain a rectified voltage; a discrete component self-oscillation circuit is used to convert the rectified voltage into a PWM voltage signal; a ripple smoothing circuit is used to remove the input AC component; a deep dimming circuit is used to stabilize the current oscillation flowing in the thyristor dimmer; and it is also used to provide a stable dynamic load when the input voltage is a phase-cut voltage.

[0030] Preferably, the EMC circuit includes an inductor L1 and a capacitor C1 to form an LC circuit to suppress the conducted interference from the outside to the drive power supply.

[0031] More specifically, the discrete component self-oscillation circuit includes a resistor R2, a resistor R3, a resistor R6, a resistor R6A, a resistor RS1, a resistor RS2, a transformer T1, a triode Q1, a triode Q2, a capacitor C5, and a diode D1.

[0032] More specifically, the resistor RS1 and the resistor RS2 are in parallel and serve as a current-limiting sampling resistor; a transformer leakage inductance discharge circuit is also provided in the discrete component self-oscillation circuit, and the transformer leakage inductance discharge circuit includes a resistor R8, a resistor R8A, a capacitor C3, and a diode D3.

[0033] In this embodiment, when the AC voltage is turned on, the rectifier filter circuit provides a DC voltage to the DC bus, generating a voltage across the resistors R2 and R3. The current passes through R2 and R3 to supply power to the base of the main switch triode Q1, and at the same time charges the VCC capacitor C5, making the main switch triode Q1 slightly conductive; the voltage is applied to the primary winding and the auxiliary winding of the transformer T1; PIN1 and PIN4 are the same-named terminals, resulting in an induced voltage on the auxiliary winding. The current flows through D1 to the base of the main switch triode Q1, accelerating the conduction of the main switch triode Q1; at this time, the current of the main switch triode Q1 flows from the collector to the emitter, through the current-limiting detection resistors RS1 / / RS2 to the ground. As the current of the main switch triode Q1 increases, the voltage across the current-limiting detection resistors RS1 / / RS2 also increases. The voltage of 0.7V is detected by the base detection resistor R9 of the triode Q2, and the triode Q2 conducts, equivalent to short-circuiting the base-emitter of the main switch triode Q1; the main switch triode Q1 stops working; when the switch Q1 is turned off. The voltage of the auxiliary winding of the transformer T1 reverses, and the current flows from the VCC end of the auxiliary winding to the resistors R6 / / R6A, through the capacitor C5 to the base of the main switch triode Q1, and the main switch triode Q1 conducts. The high-speed on / off of the main switch triode Q1 provides a continuous load energy to the secondary.

[0034] More specifically, the ripple smoothing circuit includes a capacitor C9, a capacitor C10, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a diode D11, a diode D13, a diode D14, a zener diode Z3, a zener diode Z4, and an NMOS transistor Q5.

[0035] Among them, capacitor C9 and diode D13 are connected in series and then connected to the secondary coil of the transformer, and the cathode of diode D13 is grounded; the anode of capacitor C10 is connected to resistor R21 and resistor R20 and then connected to the cathode of diode D4 and is connected in parallel to one end of capacitor C9; the other end of capacitor C9 is connected to the junction between resistor R20 and resistor R21 through resistor R19 and then through diode D11; the cathode of diode D4 is also connected in parallel with the anode of diode D14, resistor R24 and the drain of NMOS transistor Q5; the cathode of diode D14 is connected to the cathode of voltage regulator diode Z3; the source of the NMOS transistor is connected to the anode of voltage regulator diode Z4.

[0036] In this embodiment, when P6 of the main transformer T1 is at a high potential at the output end, current flows through diode D4, through resistors R20 and R21 to capacitor C10, through resistor R22 to NMOS transistor Q5, and supplies power to the G pole of the NMOS transistor. The clamping voltage regulator diode Z4 is connected in parallel between the G pole and the S pole of the NMOS transistor, so that the voltage between the G-S poles of the NMOS transistor is clamped at a voltage value. At the same time, when P6 of the main transformer T1 is at a high potential at the output end, current flows through diode D4, through resistor R24, and supplies power to the G pole of the NMOS transistor. The clamping voltage regulator diode Z4 is connected in parallel between the G pole and the S pole of the NMOS transistor, so that the voltage between the G-S poles of the NMOS transistor is clamped at a voltage value.

[0037] When P6 of the main transformer T1 is at a high potential at the output end, current flows through capacitor C9, through resistor R19, through diode D11; through resistor R21 to capacitor C10, through resistor R22 to NMOS transistor Q5, and supplies power to the G pole of the NMOS transistor. The clamping voltage regulator diode Z4 is connected in parallel between the G pole and the S pole of the NMOS transistor, so that the voltage between the G-S poles of the NMOS transistor is clamped at a voltage value. When P7 of the main transformer T1 is at a high potential at the output end, current flows through diode D13, through resistors R18 and R19, through diode D11; through resistor R21 to capacitor C10, through resistor R22 to NMOS transistor Q5, and provides continuous power supply to the G pole of the NMOS transistor.

[0038] More specifically, the deep dimming circuit includes resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, diode D8, diode D9, triode Q6 and triode Q7.

[0039] Among them, triode Q6 and triode Q7 constitute a thyristor trigger button circuit.

[0040] In this embodiment, when the output circuit works normally, the current flows from the load O+ to O-, through the parallel resistors R14 and R15 to SG; a voltage of 0.7V is generated across the resistors R14 / / R15, and then through the resistor R16 to the base of the triode Q7. At the same time, O+ goes through the resistor R13 to the collector of the triode Q7, and the triode Q7 conducts, forming a very small fake load, and the base of the triode Q6 is cut off.

[0041] When the AC input voltage is lowered, the output load voltage also decreases. When the voltage across the resistors R14 / / R15 drops to the cut-off voltage of the triode Q7, the triode Q7 turns off and stops working; the load current flows from O+ to O-, through the resistor R13 to the base of Q6, through the resistor R17 to the collector and emitter of the triode Q6, and the triode Q6 is forward-biased and conducts. R17 is a power resistor, forming a fake load in the low voltage section, which can better provide a stable dynamic load for the front-end circuit.

[0042] Preferably, this embodiment further includes a short-circuit protection circuit and an open-circuit protection circuit connected in parallel between the discrete component self-oscillation circuit and the LED load light source.

[0043] Among them, the circuit consists of the device main transformer T1, the resistors R6 / / R6A, the capacitor C5, and the main switch triode Q1. When the secondary winding of the main transformer T1 outputs a short circuit, a very small voltage is generated. At this time, the magnetic energy returned to the VCC auxiliary winding of the main transformer T1 is also very small, generating a low voltage that cannot reach the turn-on voltage of the main switch triode Q1. Therefore, the main switch triode Q1 does not work, achieving the protection of the circuit.

[0044] Among them, the circuit consists of the device zener diode Z1, the triodes Q3, Q4, the resistor R5, and the capacitor C3. When the output voltage works normally, the current flows through the zener diode Z1, through the resistor R5, the capacitor C3 to R4, through D2 to VCC, and the triodes Q3 and Q4 are cut off. When the output voltage becomes higher, the voltage at the VCC terminal of the auxiliary winding of the main transformer T1 also increases. The current flows through the resistors R6 / / R6A, through the capacitor to the base of the main switch triode Q1, a high potential is generated at the emitter of the triode Q4, and the triodes Q3 and Q4 conduct. The current flows through the zener diode to PG, and the current of the triode Q4 flows from the emitter through the collector to the zener diode Z1 to PG. The base of the main switch triode Q1 is at a low potential, and the main switch triode Q1 stops working, achieving the open-circuit protection function.

[0045] In summary, a discrete component self-oscillating thyristor deep dimming circuit proposed in this embodiment rectifies the input voltage through a rectifier filter circuit to obtain a rectified voltage. Then, the discrete component self-oscillating circuit converts the rectified voltage into a PWM voltage signal, and the ripple smoothing circuit removes the input AC component. The deep dimming circuit can stabilize the oscillation of the current flowing in the thyristor dimmer, and when the input voltage is a phase-cut voltage, the deep dimming circuit provides a stable dynamic load. The load of whether the input voltage is a phase-cut voltage or a non-phase-cut voltage is obtained to maintain the operating characteristics of the thyristor dimmer. It meets the safety requirements, is composed of conventional discrete components, has consistent and stable product performance, reduces the manufacturing economic cost, and improves the efficiency.

[0046] The above-described embodiments do not constitute a limitation on the protection scope of the technical solution. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the above embodiments shall be included in the protection scope of the technical solution.

Claims

1. A discrete component self-oscillating thyristor deep dimming circuit, where the power input terminal is connected to the circuit through a thyristor dimmer to control the LED load light source. It is characterized in that: It includes an EMC circuit, a rectifier filter circuit, a discrete component self-oscillating circuit, a ripple smoothing circuit and a deep dimming circuit; it also includes a transformer with a primary coil and a secondary coil respectively connected to the discrete component self-oscillating circuit and the ripple smoothing circuit. The rectifier filter circuit is used to rectify the input voltage to obtain a rectified voltage. The discrete component self-oscillating circuit is used to convert the rectified voltage into a PWM voltage signal. The ripple smoothing circuit is used to remove the input AC component. The deep dimming circuit is used to stabilize the current oscillation flowing in the thyristor dimmer. It is also used to provide a stable dynamic load when the input voltage is a phase-cut voltage. The deep dimming circuit includes resistor R13, resistor R14, resistor R15, resistor R16, resistor R17, diode D8, diode D9, triode Q6 and triode Q7; the base of triode Q6 is connected to the emitter of triode Q7, and after being shunted with resistor R13, it is connected to the load input terminal O+; the collector of triode Q6 is shunted and connected to the base of triode Q7, and after being connected with resistor R16, it is connected to the load output terminal O-; the emitter of triode Q6 is connected to the load input terminal O+ after passing through resistor R17; the collector of triode Q7 is connected to the load output terminal O-; after diode D9 and diode D8 are connected in series, one end is shunted and connected to the collector of triode Q7, and the other end is shunted and connected between resistor R16 and the load output terminal O-; resistor R14 and resistor R15 are connected in parallel and are arranged between the load output terminal O- and the ground terminal. In the deep dimming circuit, when the AC input voltage is lowered, the output load voltage also decreases. When the voltage across the parallel-connected resistor R14 and resistor R15 drops to the cut-off of triode Q7, triode Q7 turns off and stops working. The load current passes from the load input terminal O+ to the load output terminal O-, through resistor R13 to the base of Q6, through resistor R17 to the collector and emitter of triode Q6. Triode Q6 is forward-biased and conducts. R17 is a power resistor, forming a false load in the low voltage section to provide a stable dynamic load for the front-end circuit.

2. A discrete component self-oscillating thyristor deep dimming circuit according to claim 1. It is characterized in that: The discrete component self-oscillating circuit includes resistor R2, resistor R3, resistor R6, resistor R6A, resistor RS1, resistor RS2, transformer T1, triode Q1, triode Q2, capacitor C5 and diode D1.

3. A discrete component self-oscillating thyristor deep dimming circuit according to claim 2. It is characterized in that: Resistor RS1 and resistor RS2 are connected in parallel and serve as current-limiting sampling resistors; a transformer leakage inductance discharge circuit is also provided in the discrete component self-oscillating circuit, and the transformer leakage inductance discharge circuit includes resistor R8, resistor R8A and capacitor C6, diode D3.

4. A discrete component self-oscillating thyristor deep dimming circuit according to claim 1. It is characterized in that: The ripple smoothing circuit includes capacitor C9, capacitor C10, resistor R18, resistor R19, resistor R20, resistor R21, resistor R22, diode D11, diode D13, diode D14, zener diode Z3, zener diode Z4 and NMOS transistor Q5.

5. A discrete-component self-oscillating thyristor deep dimming circuit according to claim 4, wherein: The capacitor C9 and the diode D13 are connected in series and then connected to the secondary coil of the transformer, and the anode signal of the diode D13 is grounded; the anode of the capacitor C10 is connected to the resistors R21 and R20 and then connected to the cathode of the diode D4 and connected in parallel to one end of the capacitor C9; the other end of the capacitor C9 is connected to the resistor R19 and then connected to the resistor R20 and the resistor R21 through the diode D11; the cathode of the D4 is also connected in parallel to the anode of the diode D14, the resistor R24 and the drain of the NMOS transistor Q5; the cathode of the diode D14 is connected to the cathode of the zener diode Z3; the source of the NMOS transistor is connected to the anode of the zener diode Z4.

6. A discrete-component self-oscillating thyristor deep dimming circuit according to any one of claims 1 to 5, wherein: It further includes a short-circuit protection circuit and an open-circuit protection circuit connected in parallel between the discrete-component self-oscillating circuit and the LED load light source.

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