LED constant current power supply and lighting system with adjustable output according to number of parallel loads

Abstract

The utility model discloses a kind of LED constant-current power supplies that can be adjusted output according to load parallel quantity, comprising: light source load current detection end, it detects light source load current signal, the light source load current signal characterizes the actual working current of light source;Counting special constant-voltage power supply, it is loaded in the two ends of light source counting resistance and counting sampling resistance, light source counting resistance characterizes the quantity of parallel branch of LED light source, and the light source counting resistance is connected in series with counting sampling resistance;Counting sampling circuit, it collects the counting resistance current signal in the two ends of counting sampling resistance;Comparator circuit, it compares the light source load current signal and counting resistance current signal and exports PWM control reference signal;PWM switching power supply, it adjusts the actual working current of light source according to the PWM control reference signal.The utility model also discloses a kind of lighting system.The utility model can adjust the current compatible with it according to the different branch quantity of parallel LED light source.

Description

Technical Field

[0001] This utility model relates to LED driver power supply, and more specifically to an LED constant current power supply and lighting system that can adjust the output according to the number of loads connected in parallel. Background Technology

[0002] Existing lighting systems typically use LEDs as light sources, connected in series or parallel. Multiple LEDs connected in parallel are driven by an LED power supply. Since the operating current of each branch of the LED light source is a constant value, the total operating current required by the LEDs must increase or decrease accordingly when the number of LEDs increases or decreases. However, ordinary parallel constant current power supplies will introduce errors in the number of light sources when the number of light sources changes, resulting in output current errors. Clearly, existing LED constant current power supplies cannot accurately count the number of LEDs and cannot precisely adjust the output current based on the number of parallel LEDs, leading to a mismatch between the output current and the actual required current, thus creating output current errors. Utility Model Content

[0003] To address the technical problem that existing technologies cannot accurately adjust the output current according to the number of parallel LED light sources, resulting in a mismatch between the output current and the actual required current and thus an output current error, this utility model provides an LED constant current power supply that can adjust the output according to the number of parallel loads.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is to design an LED constant current power supply that can adjust the output according to the number of loads connected in parallel, including:

[0005] Counting sampling resistor;

[0006] The light source load current detection terminal detects the light source load current signal, which represents the actual operating current of the light source.

[0007] A constant voltage power supply for counting is applied across the light source counting resistor and the counting sampling resistor. The light source counting resistor represents the number of parallel branches of the LED light source, and the light source counting resistor is connected in series with the counting sampling resistor.

[0008] The counting sampling circuit has its input terminal connected to the counting sampling resistor and acquires the counting resistor current signal applied across the counting sampling resistor by the dedicated constant voltage power supply for counting.

[0009] The comparator circuit has one input terminal connected to the light source load current detection terminal and the other input terminal connected to the output terminal of the counting sampling circuit; the comparator circuit compares the light source load current signal and the counting resistor current signal and outputs a PWM control reference signal according to the comparison result.

[0010] The PWM switching power supply has its control input terminal connected to the output terminal of the comparator circuit. The PWM switching power supply adjusts the actual operating current of the light source according to the PWM control reference signal output by the comparator, so that the actual operating current of the light source is adapted to the number of parallel branches of the LED light source.

[0011] The dedicated constant voltage power supply for counting is connected to the PWM switching power supply. The dedicated constant voltage power supply for counting is composed of voltage division by the PWM switching power supply and combined with constant voltage components.

[0012] The dedicated constant voltage power supply for counting includes:

[0013] The negative terminal of the first Zener diode is connected to the positive output terminal of the PWM switching power supply.

[0014] The first voltage divider resistor has one end connected to the positive terminal of the first Zener diode and the other end connected to the negative output terminal of the PWM switching power supply.

[0015] The dedicated constant voltage power supply for counting includes:

[0016] The positive terminal of the second controllable precision voltage regulator is connected to the negative output terminal of the PWM switching power supply.

[0017] The second voltage divider resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative terminal of the second controllable precision voltage regulator.

[0018] The gate of the second field-effect transistor is connected to the negative terminal of the second controllable precision voltage regulator, and the source is connected to the reference terminal of the second controllable precision voltage regulator.

[0019] The second source resistor has one end connected to the source of the second field-effect transistor and the reference of the second controllable precision voltage regulator, and the other end connected to the negative output terminal of the PWM switching power supply.

[0020] The negative terminal of the second Zener diode is connected to the positive output terminal of the PWM switching power supply, and the positive terminal is connected to the drain of the second field-effect transistor.

[0021] The dedicated constant voltage power supply for counting includes:

[0022] Third voltage divider resistor;

[0023] Fourth voltage divider resistor;

[0024] The fifth voltage divider resistor, the third voltage divider resistor, the fourth voltage divider resistor and the fifth voltage divider resistor are connected in series between the positive output terminal and the negative output terminal of the PWM switching power supply;

[0025] The third controllable precision voltage regulator has its positive terminal connected between the fourth and fifth voltage divider resistors, its negative terminal connected to the positive output terminal of the PWM switching power supply, and its reference terminal connected between the third and fourth voltage divider resistors.

[0026] The dedicated constant voltage power supply for counting includes:

[0027] The fourth controllable precision voltage regulator has its positive terminal connected to the negative output terminal of the PWM switching power supply.

[0028] The sixth voltage divider resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative terminal of the fourth controllable precision voltage regulator.

[0029] The fourth field-effect transistor has its gate connected to the negative terminal of the fourth controllable precision voltage regulator, and its source connected to the reference terminal of the fourth controllable precision voltage regulator.

[0030] The fourth source resistor has one end connected to the source of the fourth field-effect transistor and the reference of the fourth controllable precision voltage regulator, and the other end connected to the negative output terminal of the PWM switching power supply.

[0031] The fourth drain resistor has one end connected to the positive output terminal of the PWM switching power supply, and the positive terminal connected to the drain of the fourth field-effect transistor.

[0032] The fourth comparator has its positive input terminal connected to the drain of the fourth field-effect transistor, and its negative input terminal connected to the output terminal of the fourth comparator.

[0033] The dedicated constant voltage power supply for counting includes:

[0034] The seventeenth resistor;

[0035] The eighteenth resistor;

[0036] The nineteenth resistor, the seventeenth resistor, the eighteenth resistor and the nineteenth resistor are connected in series between the positive output terminal and the negative output terminal of the PWM switching power supply connected in series;

[0037] The fifth controllable precision voltage regulator has its positive terminal connected between the eighteenth and nineteenth resistors, its negative terminal connected to the positive output terminal of the PWM switching power supply, and its reference terminal connected between the seventeenth and eighteenth resistors.

[0038] The counting sampling circuit includes:

[0039] The fifteenth resistor has one end connected between the light source counting resistor and the counting sampling resistor;

[0040] The sixteenth resistor has one end connected to the positive terminal of the fifth controllable precision voltage regulator.

[0041] The fourteenth resistor has one end connected to the negative output terminal of the PWM switching power supply.

[0042] The fifth comparator has its non-inverting input connected to the other end of the fourteenth resistor and the other end of the fifteenth resistor, and its inverting input connected to the other end of the sixteenth resistor.

[0043] The thirteenth resistor has one end connected to the inverting input terminal of the fifth comparator and the other end connected to the output terminal of the fifth comparator.

[0044] The twelfth resistor has its first end connected to the output of the fifth comparator.

[0045] The eleventh resistor has one end connected to the other end of the twelfth resistor, and the other end connected to the negative output terminal of the PWM switching power supply.

[0046] The comparator circuit includes:

[0047] The sixth comparator has its non-inverting input connected to the other end of the twelfth resistor, and its output connected to the control input of the PWM switching power supply.

[0048] The tenth resistor has one end connected to the inverting input terminal of the sixth comparator and the other end connected to the load current detection terminal of the light source.

[0049] The eighth resistor;

[0050] The ninth resistor, the eighth resistor and the ninth resistor are connected in series between the positive output terminal of the PWM switching power supply and the load current detection terminal of the light source;

[0051] The seventh resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative output terminal of the PWM switching power supply.

[0052] The sixth controllable precision voltage regulator has its positive terminal connected to the negative output terminal of the PWM switching power supply, its positive terminal connected to the output terminal of the sixth comparator, and its reference terminal connected between the eighth and ninth resistors.

[0053] The PWM switching power supply includes:

[0054] The first PWM chip has a feedback input terminal;

[0055] The optocoupler has its input terminal as the control input terminal of the PWM switching power supply, and its output terminal is connected to the feedback input terminal of the first PWM chip.

[0056] The dedicated constant voltage power supply for counting includes:

[0057] The seventh controllable precision voltage regulator has its positive terminal connected to the negative output terminal of the PWM switching power supply.

[0058] The twenty-first resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative terminal of the seventh controllable precision voltage regulator.

[0059] The base of the seventh transistor is connected to the negative terminal of the seventh controllable precision voltage regulator, and the emitter is connected to the reference terminal of the seventh controllable precision voltage regulator.

[0060] The twentieth resistor has one end connected to the emitter of the seventh transistor and the reference terminal of the seventh controllable precision voltage regulator, and the other end connected to the negative output terminal of the PWM switching power supply.

[0061] The seventh Zener diode has its negative terminal connected to the positive output terminal of the PWM switching power supply, and its positive terminal connected to the collector of the seventh transistor.

[0062] The counting sampling circuit includes:

[0063] The thirty-seventh resistor has one end connected to the negative output terminal of the PWM switching power supply;

[0064] The thirty-eighth resistor has one end connected between the light source counting resistor and the counting sampling resistor;

[0065] The thirty-ninth resistor has one end connected to the collector of the seventh transistor;

[0066] The seventh comparator has its non-inverting input connected to the other ends of the thirty-seventh and thirty-eighth resistors;

[0067] The thirty-sixth resistor has one end connected to the inverting input terminal of the seventh comparator and the other end connected to the output terminal of the seventh comparator.

[0068] The thirty-fifth resistor has one end connected to the output of the seventh comparator;

[0069] The comparator circuit includes:

[0070] The eighth comparator has its non-inverting input connected to the load current detection terminal of the light source.

[0071] The thirty-fourth resistor has one end connected to the negative output terminal of the PWM switching power supply, and the other end connected to the inverting input terminal of the eighth comparator and the other end of the thirty-fifth resistor.

[0072] The thirty-second resistor has one end connected to the output terminal of the eighth comparator and the other end connected to the control input terminal of the PWM switching power supply.

[0073] The thirty-third resistor has one end connected to the other end of the thirty-second resistor, and the other end connected to the negative output terminal of the PWM switching power supply.

[0074] The thirtieth resistor has one end connected to the negative output terminal of the PWM switching power supply and the other end connected to the positive input terminal of the eighth comparator.

[0075] The PWM switching power supply includes:

[0076] The second PWM chip has a feedback input terminal, which is the control input terminal of the PWM switching power supply.

[0077] This utility model also provides a lighting system, which includes a plurality of LED light sources connected in parallel and a light source counting resistor corresponding to the LED light sources; the lighting system also has the above-mentioned LED constant current power supply whose output can be adjusted according to the number of loads connected in parallel, the light source load current detection terminal is connected to the LED light source, and the LED light source is connected to the PWM switching power supply.

[0078] The light source counting resistor includes several counting resistors connected in parallel. The number of counting resistors is the same as the number of LED light sources, and each counting resistor corresponds to one LED light source.

[0079] This invention incorporates a counting sampling resistor, a light source load current detection terminal, a dedicated constant voltage power supply for counting, a counting sampling circuit, a comparator circuit, and a PWM switching power supply. The dedicated constant voltage power supply is applied across the light source counting resistor and the counting sampling resistor. The light source counting resistor represents the number of parallel branches of the LED light source. The light source counting resistor and the counting sampling resistor are connected in series. The light source load current detection terminal detects the light source load current signal, which represents the actual operating current of the light source. The counting sampling circuit acquires the counting resistor current signal applied across the counting sampling resistor by the dedicated constant voltage power supply. The comparator circuit compares the light source load current signal and the counting resistor current signal and outputs a PWM control reference signal to the PWM switching power supply based on the comparison result. The PWM switching power supply adjusts the actual operating current of the light source according to the PWM control reference signal output by the comparator, ensuring that the actual operating current of the light source matches the number of parallel branches of the LED light source. This allows for precise adjustment of the output current based on the number of parallel branches of the LED light source, ensuring that the output current matches the actual required current and reducing output current errors. Attached Figure Description

[0080] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0081] Figure 1 This is a schematic diagram of the lighting system of this utility model;

[0082] Figure 2 This is a circuit diagram of a first embodiment of the constant voltage power supply for counting in this utility model;

[0083] Figure 3 This is a circuit diagram of Embodiment 2 of the constant voltage power supply for counting in this utility model;

[0084] Figure 4 This is a circuit diagram of Embodiment 3 of the constant voltage power supply for counting in this utility model;

[0085] Figure 5 This is the circuit diagram of Embodiment 4 of the constant voltage power supply for counting in this utility model;

[0086] Figure 6 This is a circuit diagram of one embodiment of the lighting system of this utility model;

[0087] Figure 7 This is a circuit diagram of Embodiment 2 of the lighting system of this utility model. Detailed Implementation

[0088] The specific embodiments of this utility model are further described below with reference to the accompanying drawings:

[0089] Please see also Figures 1 to 7 This utility model lighting system includes an LED light source 1, a light source counting resistor 2, and an LED constant current power supply 4. Wherein:

[0090] LED light source 1 includes several LEDs connected in parallel. In this specific embodiment, all LEDs are identical, thereby ensuring that the current through each LED light source branch is the same.

[0091] The light source counting resistor 2 corresponds to the LED light source. The light source counting resistor represents the number of parallel branches of the LED light source; that is, the resistance value of the light source counting resistor is related to the number of parallel branches of the LED light source. The number of parallel branches of the LED light source can be determined by the resistance value of the light source counting resistor. The resistance value of the light source counting resistor can be constructed by multiple counting resistors. The light source counting resistor includes several parallel counting resistors, each with the same resistance value, and the number of counting resistors is proportional to the number of LED light sources. In this specific embodiment, the light source counting resistor includes several parallel counting resistors, the number of which is consistent with the number of LED light sources, and each counting resistor corresponds one-to-one with an LED light source, with each counting resistor having the same resistance value.

[0092] The LED constant current power supply 4 can adjust the output according to the number of parallel loads, that is, adjust the output current according to the number of parallel branches of LED light sources to ensure that the actual working current of each LED light source is consistent with its required current.

[0093] The LED constant current power supply 4 includes a counting sampling resistor 3, a light source load current detection terminal 41, a dedicated constant voltage power supply for counting 42, a counting sampling circuit 43, a comparator circuit 44, and a PWM switching power supply 45. Among them:

[0094] The counting sampling resistor 3 is connected to the light source counting resistor, and the light source counting resistor is connected in series with the counting sampling resistor. Since the resistance values ​​of each counting resistor and the counting sampling resistor are preset, the total resistance value of the counting resistors connected in parallel and then in series with the counting sampling resistor can be calculated. If a constant voltage is applied across the light source counting resistor and the counting sampling resistor, the total resistance value of the light source counting resistor can be obtained through the voltage or current across the counting sampling resistor, thereby determining the number of counting resistors and further determining the number of parallel branches of the LED light source.

[0095] The light source counting resistor and the counting sampling resistor are set together with the LED light source to form the light source assembly. The light source counting resistor can be integrated into the LED light source during production. Of course, the light source counting resistor can also be set synchronously according to the number of LED light source branches when the LED light source branches are connected in parallel.

[0096] The light source load current detection terminal 41 detects the light source load current signal, which represents the actual operating current of the light source. The light source load current signal can be the actual operating current of the LED light source, or a current proportional to the actual operating current of the LED light source. The light source load current detection terminal is mainly used to collect information about the actual operating current of the LED light source, so as to compare it with the current collected by the counting and sampling circuit, thereby determining whether the PWM switching power supply needs to adjust the actual operating current.

[0097] The two ends of the dedicated constant voltage power supply 42 are applied across the light source counting resistor and the counting sampling resistor. The light source counting resistor represents the number of parallel branches of the LED light source, and the light source counting resistor and the counting sampling resistor are connected in series. Due to the setting of the dedicated constant voltage power supply, the voltage applied across the light source counting resistor and the counting sampling resistor is constant. Since the counting sampling resistor is constant, when the light source counting resistor changes, the change in the light source counting resistor can be calculated by the voltage or current applied across the counting sampling resistor.

[0098] The input terminal of the counting sampling circuit 43 is connected to the counting sampling resistor and acquires the counting resistor current signal applied across the counting sampling resistor by the dedicated constant voltage power supply. The counting sampling circuit is mainly used to acquire the counting resistor current signal applied across the counting sampling resistor by the dedicated constant voltage power supply, and can convert the counting resistor current signal into a voltage value suitable for comparison as needed.

[0099] One input terminal of the comparator circuit 44 is connected to the light source load current detection terminal, and the other input terminal is connected to the output terminal of the counting sampling circuit; the comparator circuit compares the light source load current signal and the counting resistor current signal and outputs a PWM control reference signal according to the comparison result.

[0100] The control input terminal of the PWM switching power supply 45 is connected to the output terminal of the comparator circuit. The PWM switching power supply adjusts the actual operating current of the light source according to the PWM control reference signal output by the comparator, so that the actual operating current of the light source is adapted to the number of parallel branches of the LED light source. The load current detection terminal of the light source is connected to the LED light source, and the LED light source is connected to the PWM switching power supply.

[0101] When the number of parallel branches of the LED light source is increased, the number of parallel counting resistors in the light source counting resistors also increases proportionally. This reduces the total resistance of the light source counting resistors, increasing the current and voltage applied to the counting sampling resistors. Consequently, the light source load current signal across the comparator circuit becomes less than the counting resistor current signal, causing the comparator circuit to output a high or low level. The PWM switching power supply adjusts the output current until the light source load current signal is less than the counting resistor current signal. At this point, the comparator circuit output reverses, outputting a low or high level, and the PWM switching power supply stops adjusting the output current. The actual operating current of the light source is now the same as its rated current. Therefore, the output current of the PWM switching power supply can be adjusted according to the number of parallel branches of the LED light source, achieving precise adjustment of the output current and ensuring it matches the actual required current, thus reducing output current errors.

[0102] In this specific embodiment, the dedicated constant voltage power supply for counting is generated by a PWM switching power supply. The dedicated constant voltage power supply is connected to the PWM switching power supply and is constructed by dividing the voltage of the PWM switching power supply and combining it with a constant voltage element. By dividing the voltage of the PWM switching power supply and then combining it with a constant voltage element, a dedicated constant voltage power supply for counting can be constructed with a constant voltage.

[0103] Please see Figure 2In this specific embodiment, the dedicated constant voltage power supply for counting includes a first Zener diode Dz and a first voltage divider resistor R1. The negative terminal of the first Zener diode Dz is connected to the positive output terminal of the PWM switching power supply. One end of the first voltage divider resistor R1 is connected to the positive terminal of the first Zener diode, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0104] LED light sources D1, D2...Dn are connected in parallel, and counting resistors Rf1, Rf2...Rfn are connected in parallel to form the light source counting resistor. A constant voltage power supply for counting applies a constant voltage across the counting sampling resistor Rd and the light source counting resistor. The counting sampling circuit collects the current or voltage of the counting sampling resistor Rd.

[0105] Please see Figure 3 In this specific embodiment, the dedicated constant voltage power supply for counting includes a second controllable precision voltage regulator TL431, a second voltage divider resistor R1, a second field-effect transistor Q1, a second source resistor R2, and a second Zener diode Dz. Wherein:

[0106] The positive terminal of the second controllable precision voltage regulator TL431 is connected to the negative output terminal of the PWM switching power supply.

[0107] One end of the second voltage divider resistor R1 is connected to the positive output terminal of the PWM switching power supply, and the other end is connected to the negative terminal of the second controllable precision voltage regulator.

[0108] The gate of the second field-effect transistor Q1 is connected to the negative terminal of the second controllable precision voltage regulator, and the source is connected to the reference terminal of the second controllable precision voltage regulator.

[0109] One end of the second source resistor R2 is connected to the source of the second field-effect transistor and the reference terminal of the second controllable precision voltage regulator, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0110] The negative terminal of the second Zener diode Dz is connected to the positive output terminal of the PWM switching power supply, and the positive terminal is connected to the drain of the second field-effect transistor.

[0111] LED light sources D1, D2...Dn are connected in parallel, and counting resistors Rf1, Rf2...Rfn are connected in parallel to form the light source counting resistor. A constant voltage power supply for counting applies a constant voltage across the counting sampling resistor Rd and the light source counting resistor. The counting sampling circuit collects the current or voltage of the counting sampling resistor Rd.

[0112] Please see Figure 4 In this specific embodiment, the dedicated constant voltage power supply for counting includes a third voltage divider resistor R1, a fourth voltage divider resistor R2, a fifth voltage divider resistor R3, and a third controllable precision voltage regulator TL431. Wherein:

[0113] The third voltage divider resistor R1, the fourth voltage divider resistor R2, and the fifth voltage divider resistor R3 are connected in series between the positive output terminal and the negative output terminal of the PWM switching power supply.

[0114] The positive terminal of the third controllable precision voltage regulator TL431 is connected between the fourth and fifth voltage divider resistors, the negative terminal is connected to the positive output terminal of the PWM switching power supply, and the reference terminal is connected between the third and fourth voltage divider resistors.

[0115] LED light sources D1, D2...Dn are connected in parallel, and counting resistors Rf1, Rf2...Rfn are connected in parallel to form the light source counting resistor. A constant voltage power supply for counting applies a constant voltage across the counting sampling resistor Rd and the light source counting resistor. The counting sampling circuit collects the current or voltage of the counting sampling resistor Rd.

[0116] Please see Figure 5 In this specific embodiment, the dedicated constant voltage power supply for counting includes a fourth controllable precision voltage regulator TL431, a sixth voltage divider resistor R1, a fourth field-effect transistor Q1, a fourth source resistor R3, a fourth drain resistor R2, and a fourth comparator Q2.

[0117] in:

[0118] The positive terminal of the fourth controllable precision voltage regulator TL431 is connected to the negative output terminal of the PWM switching power supply.

[0119] One end of the sixth voltage divider resistor R1 is connected to the positive output terminal of the PWM switching power supply, and the other end is connected to the negative terminal of the fourth controllable precision voltage regulator.

[0120] The gate of the fourth field-effect transistor Q1 is connected to the negative terminal of the fourth controllable precision voltage regulator, and the source is connected to the reference terminal of the fourth controllable precision voltage regulator.

[0121] One end of the fourth source resistor R3 is connected to the source of the fourth field-effect transistor and the reference terminal of the fourth controllable precision voltage regulator, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0122] One end of the fourth drain resistor R2 is connected to the positive output terminal of the PWM switching power supply, and the positive terminal is connected to the drain of the fourth field-effect transistor.

[0123] The positive input terminal of the fourth comparator Q2 is connected to the drain of the fourth field-effect transistor, and the negative input terminal is connected to the output terminal of the fourth comparator.

[0124] Please see Figure 6In this specific embodiment, the dedicated constant voltage power supply for counting includes a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, and a fifth controllable precision voltage regulator U04. Wherein:

[0125] The seventeenth resistor R17, the eighteenth resistor R18, and the nineteenth resistor R19 are connected in series between the positive output terminal and the negative output terminal of the PWM switching power supply.

[0126] The positive terminal of the fifth controllable precision voltage regulator U04 is connected between the eighteenth and nineteenth resistors, the negative terminal is connected to the positive output terminal of the PWM switching power supply, and the reference terminal is connected between the seventeenth and eighteenth resistors.

[0127] The counting and sampling circuit includes a fifteenth resistor R15, a sixteenth resistor R16, a fourteenth resistor R14, a fifth comparator U03-2, a thirteenth resistor R13, a twelfth resistor R12, and an eleventh resistor R11. Wherein:

[0128] One end of the fifteenth resistor R15 is connected between the light source counting resistor and the counting sampling resistor.

[0129] One end of the sixteenth resistor R16 is connected to the positive terminal of the fifth controllable precision voltage regulator.

[0130] One end of the fourteenth resistor R14 is connected to the negative output terminal of the PWM switching power supply.

[0131] The non-inverting input of the fifth comparator U03-2 is connected to the other end of the fourteenth resistor and the other end of the fifteenth resistor, and its inverting input is connected to the other end of the sixteenth resistor.

[0132] One end of the thirteenth resistor R13 is connected to the inverting input of the fifth comparator, and the other end is connected to the output of the fifth comparator.

[0133] One end of the twelfth resistor R12 is connected to the output of the fifth comparator.

[0134] One end of the eleventh resistor R11 is connected to the other end of the twelfth resistor, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0135] The comparator circuit includes a sixth comparator U03-1, a tenth resistor R10, an eighth resistor R8, a ninth resistor R9, a seventh resistor Rs, and a sixth controllable precision voltage regulator U02. Wherein:

[0136] The non-inverting input of the sixth comparator U03-1 is connected to the other end of the twelfth resistor, and its output is connected to the control input of the PWM switching power supply.

[0137] One end of the tenth resistor R10 is connected to the inverting input of the sixth comparator, and the other end is connected to the load current detection terminal of the light source.

[0138] The eighth resistor R8 and the ninth resistor R9 are connected in series between the positive output terminal of the PWM switching power supply and the load current detection terminal of the light source.

[0139] One end of the seventh resistor Rs is connected to the positive output terminal of the PWM switching power supply, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0140] The positive terminal of the sixth controllable precision voltage regulator U02 is connected to the negative output terminal of the PWM switching power supply, and the positive terminal is connected to the output terminal of the sixth comparator. The reference terminal is connected between the eighth resistor and the ninth resistor.

[0141] The PWM switching power supply includes a first PWM chip U01 and its peripheral circuitry, and an optocoupler PC817. Wherein:

[0142] The first PWM chip U01 has a feedback input terminal.

[0143] The input terminal of the optocoupler PC817 is the control input terminal of the PWM switching power supply, and its output terminal is connected to the feedback input terminal of the first PWM chip.

[0144] LED light sources D1, D2...Dn are connected in parallel, and counting resistors Rf1, Rf2...Rfn are connected in parallel to form the light source counting resistor Rf. A constant voltage power supply for counting applies a constant voltage across the counting sampling resistor Rd and the light source counting resistor. The counting sampling circuit collects the current or voltage of the counting sampling resistor Rd.

[0145] The dedicated constant voltage power supply for counting forms a voltage divider through the counting sampling resistor Rd and the light source counting resistor Rf connected in series with it. The counting resistor current signal is output from the Rd terminal. This counting resistor current signal is then output as a suitable signal voltage by the fifth comparator U03-2, which is used as a reference signal voltage input to the positive terminal of the sixth comparator U03-1. The negative terminal of the sixth comparator U03-1 receives the light source load current signal. When the light source load current signal voltage is less than the voltage converted from the counting resistor current signal, the sixth comparator U03-1 outputs a high level, the optocoupler PC817 is turned off, and the first PWM chip U01 drives the power switch Q01 to remain on. When the light source load current signal voltage is greater than the voltage converted from the counting resistor current signal, the sixth comparator U03-1 outputs a low level, the optocoupler PC817 is turned on, and the first PWM chip U01 turns off the power switch Q01.

[0146] Please see Figure 7In this specific embodiment, the dedicated constant voltage power supply for counting includes a seventh controllable precision voltage regulator U03, a twenty-first resistor R11, a seventh transistor Q02, a twentieth resistor R10, and a seventh Zener diode Dz. Wherein:

[0147] The positive terminal of the seventh controllable precision voltage regulator U03 is connected to the negative output terminal of the PWM switching power supply.

[0148] One end of the twenty-first resistor R11 is connected to the positive output terminal of the PWM switching power supply, and the other end is connected to the negative terminal of the seventh controllable precision voltage regulator.

[0149] The base of the seventh transistor Q02 is connected to the negative terminal of the seventh controllable precision voltage regulator, and the emitter is connected to the reference terminal of the seventh controllable precision voltage regulator.

[0150] One end of the twentieth resistor R10 is connected to the emitter of the seventh transistor and the reference terminal of the seventh controllable precision voltage regulator, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0151] The negative terminal of the seventh Zener diode Dz is connected to the positive output terminal of the PWM switching power supply, and the positive terminal is connected to the collector of the seventh transistor.

[0152] The counting and sampling circuit includes resistors R07 (37th), R08 (38th), R09 (39th), comparator U02-2 (7th), R06 (36th), and R05 (35th). Wherein:

[0153] One end of the thirty-seventh resistor R07 is connected to the negative output terminal of the PWM switching power supply.

[0154] One end of the thirty-eighth resistor R08 is connected between the light source counting resistor and the counting sampling resistor.

[0155] One end of the thirty-ninth resistor R09 is connected to the collector of the seventh transistor.

[0156] The non-inverting input of the seventh comparator U02-2 is connected to the other end of the thirty-seventh resistor and the other end of the thirty-eighth resistor.

[0157] One end of the thirty-sixth resistor R06 is connected to the inverting input of the seventh comparator, and the other end is connected to the output of the seventh comparator.

[0158] One end of the thirty-fifth resistor R05 is connected to the output of the seventh comparator.

[0159] The comparator circuit includes an eighth comparator U02-1, a thirty-fourth resistor R04, a thirty-second resistor R02, a thirty-third resistor R03, and a thirtieth resistor Rs. Wherein:

[0160] The non-inverting input of the eighth comparator U02-1 is connected to the load current detection terminal of the light source. The non-inverting input of the eighth comparator U02-1 is connected to the LED light source through the field-effect transistor Q01 and the inductor L01.

[0161] One end of the thirty-fourth resistor R04 is connected to the negative output terminal of the PWM switching power supply, and the other end is connected to the inverting input terminal of the eighth comparator and the other end of the thirty-fifth resistor.

[0162] One end of the thirty-second resistor R02 is connected to the output terminal of the eighth comparator, and the other end is connected to the control input terminal of the PWM switching power supply.

[0163] One end of the thirty-third resistor R03 is connected to the other end of the thirty-second resistor, and the other end is connected to the negative output terminal of the PWM switching power supply.

[0164] One end of the thirtieth resistor Rs is connected to the negative output terminal of the PWM switching power supply, and the other end is connected to the positive input terminal of the eighth comparator.

[0165] The PWM switching power supply includes a second PWM chip U01 and its peripheral circuitry. The second PWM chip U01 has a feedback input terminal, which is also the control input terminal of the PWM switching power supply.

[0166] LED light sources D1, D2...Dn are connected in parallel, and counting resistors Rf1, Rf2...Rfn are connected in parallel to form the light source counting resistor. A constant voltage power supply for counting applies a constant voltage across the counting sampling resistor Rd and the light source counting resistor. The counting sampling circuit collects the current or voltage of the counting sampling resistor Rd.

[0167] The dedicated constant voltage power supply for counting forms a voltage divider through the counting sampling resistor Rd and the light source counting resistor Rf connected in series with it. The light source count signal is output from the Rd terminal. The count signal is then output as a suitable signal voltage by the seventh comparator U02-2, which is used as a reference signal voltage and input to the negative terminal of the eighth comparator U02-1. The positive terminal of the eighth comparator U02-1 receives the light source load current signal. When the light source load current signal voltage is less than the voltage converted from the counting resistor current signal, the eighth comparator U02-1 outputs a low level, and the PWM switching power supply drives the power switch Q01 to remain on. When the light source load current signal voltage is greater than the voltage converted from the counting resistor current signal, the eighth comparator U02-1 outputs a high level, and the PWM switching power supply turns off the power switch Q01.

[0168] This invention incorporates a counting sampling resistor, a light source load current detection terminal, a dedicated constant voltage power supply for counting, a counting sampling circuit, a comparator circuit, and a PWM switching power supply. The dedicated constant voltage power supply is applied across the light source counting resistor and the counting sampling resistor. The light source counting resistor represents the number of parallel branches of the LED light source. The light source counting resistor and the counting sampling resistor are connected in series. The light source load current detection terminal detects the light source load current signal, which represents the actual operating current of the light source. The counting sampling circuit acquires the counting resistor current signal applied across the counting sampling resistor by the dedicated constant voltage power supply. The comparator circuit compares the light source load current signal and the counting resistor current signal and outputs a PWM control reference signal to the PWM switching power supply based on the comparison result. The PWM switching power supply adjusts the actual operating current of the light source according to the PWM control reference signal output by the comparator, ensuring that the actual operating current of the light source matches the number of parallel branches of the LED light source. This allows for precise adjustment of the output current based on the number of parallel branches of the LED light source, ensuring that the output current matches the actual required current and reducing output current errors.

[0169] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A constant current power supply for LEDs whose output can be adjusted according to the number of loads connected in parallel, characterized in that... include: Counting sampling resistor; The light source load current detection terminal detects the light source load current signal, which represents the actual operating current of the light source. A constant voltage power supply for counting is provided, with its two ends applied across the light source counting resistor and the counting sampling resistor. The light source counting resistor represents the number of parallel branches of the LED light source, and the light source counting resistor is connected in series with the counting sampling resistor. The counting sampling circuit has its input terminal connected to the counting sampling resistor and acquires the counting resistor current signal applied across the counting sampling resistor by the dedicated constant voltage power supply for counting. The comparator circuit has one input terminal connected to the light source load current detection terminal and the other input terminal connected to the output terminal of the counting sampling circuit; the comparator circuit compares the light source load current signal and the counting resistor current signal and outputs a PWM control reference signal according to the comparison result. The PWM switching power supply has its control input terminal connected to the output terminal of the comparator circuit. The PWM switching power supply adjusts the actual operating current of the light source according to the PWM control reference signal output by the comparator, so that the actual operating current of the light source is adapted to the number of parallel branches of the LED light source.

2. The LED constant current power supply with adjustable output according to the number of parallel loads as described in claim 1, characterized in that: The dedicated constant voltage power supply for counting is connected to the PWM switching power supply. The dedicated constant voltage power supply for counting is composed of voltage division by the PWM switching power supply and combined with constant voltage components.

3. The LED constant current power supply with adjustable output according to the number of parallel loads as described in claim 2, characterized in that: The dedicated constant voltage power supply for counting includes: The negative terminal of the first Zener diode is connected to the positive output terminal of the PWM switching power supply. The first voltage divider resistor has one end connected to the positive terminal of the first Zener diode and the other end connected to the negative output terminal of the PWM switching power supply.

4. The LED constant current power supply with adjustable output according to the number of parallel loads as described in claim 2, characterized in that: The dedicated constant voltage power supply for counting includes: The positive terminal of the second controllable precision voltage regulator is connected to the negative output terminal of the PWM switching power supply. The second voltage divider resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative terminal of the second controllable precision voltage regulator. The gate of the second field-effect transistor is connected to the negative terminal of the second controllable precision voltage regulator, and the source is connected to the reference terminal of the second controllable precision voltage regulator. The second source resistor has one end connected to the source of the second field-effect transistor and the reference of the second controllable precision voltage regulator, and the other end connected to the negative output terminal of the PWM switching power supply. The negative terminal of the second Zener diode is connected to the positive output terminal of the PWM switching power supply, and the positive terminal is connected to the drain of the second field-effect transistor.

5. The LED constant current power supply with adjustable output according to the number of parallel loads as described in claim 2, characterized in that: The dedicated constant voltage power supply for counting includes: Third voltage divider resistor; Fourth voltage divider resistor; The fifth voltage divider resistor, the third voltage divider resistor, the fourth voltage divider resistor and the fifth voltage divider resistor are connected in series between the positive output terminal and the negative output terminal of the PWM switching power supply; The third controllable precision voltage regulator has its positive terminal connected between the fourth and fifth voltage divider resistors, its negative terminal connected to the positive output terminal of the PWM switching power supply, and its reference terminal connected between the third and fourth voltage divider resistors.

6. The LED constant current power supply with adjustable output according to the number of loads connected in parallel as described in claim 2, characterized in that: The dedicated constant voltage power supply for counting includes: The fourth controllable precision voltage regulator has its positive terminal connected to the negative output terminal of the PWM switching power supply. The sixth voltage divider resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative terminal of the fourth controllable precision voltage regulator. The fourth field-effect transistor has its gate connected to the negative terminal of the fourth controllable precision voltage regulator, and its source connected to the reference terminal of the fourth controllable precision voltage regulator. The fourth source resistor has one end connected to the source of the fourth field-effect transistor and the reference of the fourth controllable precision voltage regulator, and the other end connected to the negative output terminal of the PWM switching power supply. The fourth drain resistor has one end connected to the positive output terminal of the PWM switching power supply, and the positive terminal connected to the drain of the fourth field-effect transistor. The fourth comparator has its positive input terminal connected to the drain of the fourth field-effect transistor, and its negative input terminal connected to the output terminal of the fourth comparator.

7. The LED constant current power supply with adjustable output according to the number of parallel loads as described in claim 1, characterized in that: The dedicated constant voltage power supply for counting includes: The seventeenth resistor; The eighteenth resistor; The nineteenth resistor, the seventeenth resistor, the eighteenth resistor and the nineteenth resistor are connected in series between the positive output terminal and the negative output terminal of the PWM switching power supply connected in series; The fifth controllable precision voltage regulator has its positive terminal connected between the eighteenth and nineteenth resistors, its negative terminal connected to the positive output terminal of the PWM switching power supply, and its reference terminal connected between the seventeenth and eighteenth resistors. The counting sampling circuit includes: The fifteenth resistor has one end connected between the light source counting resistor and the counting sampling resistor; The sixteenth resistor has one end connected to the positive terminal of the fifth controllable precision voltage regulator. The fourteenth resistor has one end connected to the negative output terminal of the PWM switching power supply. The fifth comparator has its non-inverting input connected to the other end of the fourteenth resistor and the other end of the fifteenth resistor, and its inverting input connected to the other end of the sixteenth resistor. The thirteenth resistor has one end connected to the inverting input terminal of the fifth comparator and the other end connected to the output terminal of the fifth comparator. The twelfth resistor has its first end connected to the output of the fifth comparator. The eleventh resistor has one end connected to the other end of the twelfth resistor, and the other end connected to the negative output terminal of the PWM switching power supply. The comparator circuit includes: The sixth comparator has its non-inverting input connected to the other end of the twelfth resistor, and its output connected to the control input of the PWM switching power supply. The tenth resistor has one end connected to the inverting input terminal of the sixth comparator and the other end connected to the load current detection terminal of the light source. The eighth resistor; The ninth resistor, the eighth resistor and the ninth resistor are connected in series between the positive output terminal of the PWM switching power supply and the load current detection terminal of the light source; The seventh resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative output terminal of the PWM switching power supply. The sixth controllable precision voltage regulator has its positive terminal connected to the negative output terminal of the PWM switching power supply, its positive terminal connected to the output terminal of the sixth comparator, and its reference terminal connected between the eighth and ninth resistors. The PWM switching power supply includes: The first PWM chip has a feedback input terminal; The optocoupler has its input terminal as the control input terminal of the PWM switching power supply, and its output terminal is connected to the feedback input terminal of the first PWM chip.

8. The LED constant current power supply with adjustable output according to the number of parallel loads as described in claim 1, characterized in that: The dedicated constant voltage power supply for counting includes: The seventh controllable precision voltage regulator has its positive terminal connected to the negative output terminal of the PWM switching power supply. The twenty-first resistor has one end connected to the positive output terminal of the PWM switching power supply and the other end connected to the negative terminal of the seventh controllable precision voltage regulator. The base of the seventh transistor is connected to the negative terminal of the seventh controllable precision voltage regulator, and the emitter is connected to the reference terminal of the seventh controllable precision voltage regulator. The twentieth resistor has one end connected to the emitter of the seventh transistor and the reference terminal of the seventh controllable precision voltage regulator, and the other end connected to the negative output terminal of the PWM switching power supply. The seventh Zener diode has its negative terminal connected to the positive output terminal of the PWM switching power supply, and its positive terminal connected to the collector of the seventh transistor. The counting sampling circuit includes: The thirty-seventh resistor has one end connected to the negative output terminal of the PWM switching power supply; The thirty-eighth resistor has one end connected between the light source counting resistor and the counting sampling resistor; The thirty-ninth resistor has one end connected to the collector of the seventh transistor; The seventh comparator has its non-inverting input connected to the other ends of the thirty-seventh and thirty-eighth resistors; The thirty-sixth resistor has one end connected to the inverting input terminal of the seventh comparator and the other end connected to the output terminal of the seventh comparator. The thirty-fifth resistor has one end connected to the output of the seventh comparator; The comparator circuit includes: The eighth comparator has its non-inverting input connected to the load current detection terminal of the light source. The thirty-fourth resistor has one end connected to the negative output terminal of the PWM switching power supply, and the other end connected to the inverting input terminal of the eighth comparator and the other end of the thirty-fifth resistor. The thirty-second resistor has one end connected to the output terminal of the eighth comparator and the other end connected to the control input terminal of the PWM switching power supply. The thirty-third resistor has one end connected to the other end of the thirty-second resistor, and the other end connected to the negative output terminal of the PWM switching power supply. The thirtieth resistor has one end connected to the negative output terminal of the PWM switching power supply and the other end connected to the positive input terminal of the eighth comparator. The PWM switching power supply includes: The second PWM chip has a feedback input terminal, which is the control input terminal of the PWM switching power supply.

9. A lighting system comprising a plurality of LED light sources connected in parallel and light source counting resistors corresponding to the LED light sources; characterized in that: The lighting system further comprises an LED constant current power supply as described in any one of claims 1-8, the output of which can be adjusted according to the number of loads connected in parallel, wherein the load current detection terminal of the light source is connected to the LED light source, and the LED light source is connected to the PWM switching power supply.

10. The lighting system according to claim 9, characterized in that: The light source counting resistor includes several counting resistors connected in parallel. The number of counting resistors is the same as the number of LED light sources, and each counting resistor corresponds one-to-one with an LED light source. The resistance value of each counting resistor is the same.

Images