Low-cost power supply circuit

Abstract

The utility model discloses a low-cost power supply circuit, comprising a master control module, a switch module, an inductor L1 and a sampling module, the switch module is electrically connected with one end of the inductor L1, and the other end of the inductor L1 is electrically connected with the sampling module; the sampling module samples the average value of the electric signals of the inductor L1 in real time to obtain a third sampling signal, the third sampling signal is sent to the main control module to be compared with a preset reference signal to generate an error signal, and the main control module adjusts the first reference Vref1 and the second reference Vref2 according to the error signal to reduce the error signal.

Description

Technical Field

[0001] This utility model relates to the field of LED driver power supply technology, and in particular to a low-cost power supply circuit. Background Technology

[0002] Currently, the application of BUCK step-down control chips is relatively mature, and their stability and reliability provide diverse options for LED constant current lighting power supplies. However, in the new era of rapid development of AI, stability and reliability are no longer sufficient to meet market demands. High precision, intelligence, functional expandability, market compatibility, and other user-friendly and market-oriented features are also required. In the existing market, only digital power supplies can meet these requirements. However, existing digital power supplies have high requirements for digital control units, complex structures, and are difficult to develop. They also require highly specialized developers and have long development cycles, significantly increasing power supply costs. Therefore, digital power supplies are mostly used in high-power, high-end equipment and are rarely used in lighting power supplies, especially in commercial and residential power supplies. Utility Model Content

[0003] The purpose of this invention is to solve at least one of the technical problems existing in the prior art, and to provide a low-cost power supply circuit that is simple in structure and can achieve precise digital control.

[0004] A low-cost power supply circuit according to an embodiment of the present invention includes: a main control module, a switching module, an inductor L1, and a sampling module. The main control module includes a sampling comparator, an error comparator, and a digital processor. The switching module is electrically connected to one end of the inductor L1, and the other end of the inductor L1 is electrically connected to the sampling module. When the inductor L1 is charging, the sampling module samples the peak value of the electrical signal of the inductor L1 to obtain a first sampling signal, and sends the first sampling signal to the sampling comparator for comparison with a first reference Vref1. When the first sampling signal exceeds the first reference Vref1, the sampling comparator generates a braking signal to turn off the switching module, thereby turning on the inductor L1. Upon initial discharge, the sampling module samples the electrical signal of inductor L1 to obtain a second sampling signal, and sends the second sampling signal to the sampling comparator for comparison with a second reference Vref2. When the second sampling signal is lower than the second reference Vref2, the sampling comparator sends a reset signal to turn on the switching module, causing inductor L1 to start charging. The sampling module samples the average value of the electrical signal of inductor L1 in real time to obtain a third sampling signal, and sends the third sampling signal to the error comparator for comparison with a preset reference signal to generate an error signal. The digital processor adjusts the first reference Vref1 and the second reference Vref2 according to the error signal to reduce the error signal.

[0005] The low-cost power supply circuit according to the embodiments of this utility model has at least the following beneficial effects: First, this utility model utilizes the characteristic that the inductive current of inductor L1 does not change abruptly to control the current; when inductor L1 is charging, the sampling module sends the first sampling signal obtained by sampling to the main control module for comparison with the first reference Vref1. When the first sampling signal exceeds the first reference Vref1, the main control module generates a braking signal to turn off the switching module, causing inductor L1 to start discharging; then, the sampling module sends the second sampling signal obtained by sampling to the main control module for comparison with the second reference Vref2. When the second sampling signal is lower than the second reference Vref2, the main control module sends a reset signal to turn on the switching module, causing inductor L1 to start charging again; this cycle repeats, allowing the low-cost power supply circuit to automatically operate in an open-loop state, and allowing inductor L1 to operate in a frequency conversion continuous operating mode throughout the entire process. Furthermore, the sampling module samples the average value of the electrical signal of inductor L1 in real time to obtain the third sampling signal, and sends the third sampling signal to the main control module to compare with the preset reference signal to generate an error signal. The main control module adjusts the first reference Vref1 and the second reference Vref2 according to the error signal to reduce the error signal, so that the error signal tends to zero, thereby realizing the closed-loop control of real-time detection and adjustment of the output current, achieving the effect of digital and precise closed-loop control. 1. Compared to traditional control systems that enter DCM discontinuous mode at low current, this invention, because inductor L1 operates in frequency conversion continuous mode throughout, ensures that the power supply remains in critical continuous mode even when dimmed to low current. This reduces EMI interference, decreases flicker coefficient at low current, and improves power supply performance. 2. The key feature of this invention is that it utilizes the hardware functions of the main control module (sampling comparator, error comparator, and brake reset function) without requiring software intervention in cycle-by-cycle current control. This significantly reduces the clock frequency requirements of the main control module, thereby substantially lowering its cost. Furthermore, by combining the data processing capabilities of a digital processor, it achieves a precise digital control closed loop, reducing the complexity of digital systems and paving the way for the widespread application of digital control power supplies.

[0006] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0007] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings;

[0008] Figure 1 This is a circuit block diagram of a low-cost power supply circuit;

[0009] Figure 2 This is the schematic diagram of a low-cost power supply circuit in constant current mode;

[0010] Figure 3 It is a waveform diagram of the working modes;

[0011] Figure 4 This is a schematic diagram of a low-cost power supply circuit in constant voltage mode. Detailed Implementation

[0012] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0013] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0014] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is used in the description, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0015] Reference Figures 1 to 4This utility model provides a low-cost power supply circuit, including: a main control module 10, a switching module 11, an inductor L1, and a sampling module. The main control module 10 includes a sampling comparator, an error comparator, and a digital processor. The switching module 11 is electrically connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the sampling module. When the inductor L1 is charging, the sampling module samples the peak value of the electrical signal of the inductor L1 to obtain a first sampling signal, and sends the first sampling signal to the sampling comparator for comparison with a first reference (peak-wave reference) Vref1. When the first sampling signal exceeds the first reference Vref1, the sampling comparator generates a braking signal to turn off the switching module 11, causing the inductor L1 to start discharging. The sampling module samples the electrical signal of the inductor L1 to obtain... The second sampled signal is sent to a sampling comparator for comparison with the second reference (zero-crossing sampling reference) Vref2. When the second sampled signal is lower than the second reference Vref2, the sampling comparator sends a reset signal to turn on the switch module 11, causing the inductor L1 to start charging. The sampling module samples the average value of the electrical signal of the inductor L1 in real time to obtain the third sampled signal, and sends the third sampled signal to an error comparator for comparison with a preset reference signal to generate an error signal. The digital processor adjusts the first reference Vref1 and the second reference Vref2 according to the error signal to reduce the error signal, thereby realizing closed-loop control of real-time detection and adjustment of the output current / voltage, achieving a precise digital closed-loop control effect.

[0016] In some embodiments, the sampling module includes an A / D sampling circuit that converts the sampled analog signal into a digital signal for input to the main control module 10. In some embodiments, the main control module 10 includes an A / D sampling circuit, with the sampling module electrically connected to the input of the A / D sampling circuit and the output of the A / D sampling circuit electrically connected to the input of a sampling comparator. The A / D sampling circuit converts the sampled analog signal into corresponding digital first sampling signal and digital second sampling signal, respectively, for comparison with corresponding first reference Vref1 and second reference Vref2.

[0017] In some embodiments, the sampling module includes a sampling circuit 13 and an average value sampling circuit 14. The sampling circuit is used to sample the peak value of the electrical signal of the inductor L1, and the average value sampling circuit samples the average value of the electrical signal of the inductor L1.

[0018] Furthermore, such as Figure 2As shown, the sampling comparator includes a peak sampling comparator CMP1 and a zero-crossing sampling comparator CMP2. The non-inverting input of the peak sampling comparator CMP1 is input to a first reference Vref1, and the non-inverting input of the zero-crossing sampling comparator CMP2 is input to a second reference Vref2. The sampling circuit inputs the first sampling signal to the inverting input of the peak sampling comparator CMP1 for comparison with the first reference Vref1, and the sampling circuit sends the second sampling signal to the inverting input of the zero-crossing sampling comparator CMP2 for comparison with the second reference Vref2.

[0019] Furthermore, it also includes an amplifier circuit for amplifying the first and second sampled signals. One end of the amplifier circuit is electrically connected to the output of the sampling circuit, and the other end is electrically connected to the input of the sampling comparator. Existing operational amplifier circuits can be used for the amplifier circuit.

[0020] Furthermore, it also includes a drive module for driving the switch module 11. The input terminal of the drive module is electrically connected to the main control module 10, and the output terminal of the drive module is electrically connected to the switch module 11. The brake signal / reset signal generated by the sampling comparator is used to control the drive module to turn the switch module 11 off / on, respectively. The drive module can use existing drive circuits such as a half-bridge driver.

[0021] In some embodiments, the main control module 10 uses an existing MCU / DSP chip, which includes a PWM controller. The braking signal and reset signal generated by the sampling comparator are respectively input to the PWM controller. The PWM controller controls the drive module to turn the switch module 11 off / on according to the received braking signal / reset signal.

[0022] Furthermore, in order to improve the quality of the output current, a rectifier and filter module 17 is provided at the output end of the low-cost power supply circuit.

[0023] Figure 2 This is a low-cost power supply circuit in constant current mode. The input terminal of the rectifier and filter module 17 is electrically connected to the output terminal of the inductor L1. The output terminal of the rectifier and filter module 17 is electrically connected to one end of the sampling circuit and the input terminal of the average value sampling circuit. The other end of the sampling circuit is grounded. That is, the average value sampling circuit samples the average current. Based on the above explanation of the principle of this low-cost power supply circuit, it can be seen that this is a low-cost power supply circuit in constant current mode.

[0024] In some embodiments, the sampling circuit 13 includes a sampling resistor Rs, the rectifier and filter module 17 includes a capacitor Co, and the switching module 11 includes MOSFETs Q1 and Q2. The gate of MOSFET Q1 is electrically connected to one output terminal of the driving module, and the gate of MOSFET Q2 is electrically connected to the other output terminal of the driving module. The drain of MOSFET Q1 is connected to the positive terminal of the power supply Vin. The source of MOSFET Q1 is electrically connected to the drain of MOSFET Q2 and one end of inductor L1, respectively. The other end of inductor L1 is electrically connected to one end of capacitor Co, and the other end of capacitor Co is electrically connected to one end of the sampling resistor Rs, the input terminal of the amplifier circuit, and the input terminal of the average value sampling circuit, respectively. The other end of the sampling resistor Rs and the source of MOSFET Q2 are grounded. 1. When Q1 is turned on, current flows through the MOSFET to the inductor L1, and the inductor L1 begins to charge. After being filtered by capacitor Co, the current flows through the load RL, and then through the sampling resistor Rs back to the power supply Vin, forming an inductor charging circuit. As the inductor current continues to increase, it is converted by the A / D sampling circuit and sent to the peak sampling comparator CMP1. When the first sampling signal exceeds the first reference Vref1, a braking signal is generated and sent to the PWM controller. After receiving the braking signal, the PWM controller sets the PWM signal low, and the MOSFET Q1 is turned off. 2. When MOSFET Q1 is turned off and passes through the dead zone, MOSFET Q2 turns on. At this time, the current flows through inductor L1, through capacitor Co for filtering, through load RL, then through sampling resistor Rs, and back to inductor L1 via MOSFET Q2, forming an inductor discharge loop. As the inductor current continuously decreases, it is converted by the A / D sampling circuit and sent to the zero-crossing sampling comparator CMP2. When the second sampling signal is lower than the second reference Vref2, a reset signal is generated and sent to the PWM controller. After receiving the reset signal, the PWM controller sets the PWM signal high, MOSFET Q2 turns off, and after passing through the dead zone MOSFET, Q1 turns on again. This process repeats, forming an open-loop control system. 3. In the open-loop system, the average value of the sampling current of sampling resistor Rs (the third sampling signal) is sent to the error comparator and compared with the preset reference current. An error signal is generated, which is then processed by PID control, limited, and sent to the digital processor to adjust Vref1 and Vref2, thereby realizing peak control of the inductor current. This constructs a peak control critical continuous mode BUCK buck digital control system. The operating modes are as follows: Figure 3As shown, t0-t1: PWM controller resets, dead time is executed; t1-t2: PWM controller starts counting, PWM control signal output is high, Q1 is on, Q2 is off, L1 starts charging, and power supply Vin charges Co and supplies power to the RL load. t2-t3: PWM controller receives braking signal, PWM controller outputs low level, Q1 is turned off, dead time is executed. t3-t4: Q2 is on, inductor starts discharging, RL load is supplied by inductor L1 and Co. t4-t5: PWM controller receives reset signal, PWM controller resets, Q2 is turned off, dead time is executed. t5-t6: PWM controller resets, dead time is executed, the next cycle begins.

[0025] This invention can achieve constant voltage mode not only in constant current mode, but also by changing the connection point of the average value sampling circuit. Figure 4 This is a low-cost power supply circuit in constant voltage mode. The output terminal of the rectifier and filter module 17 is electrically connected to the sampling circuit 13, and the average value sampling circuit 14 is electrically connected to the output terminal of the inductor L1 and the input terminal of the rectifier and filter module 17, respectively. Based on the foregoing explanation of the principle of this low-cost power supply circuit and common circuit knowledge, it can be seen that this is a low-cost power supply circuit in constant voltage mode.

[0026] This invention allows for the external peak sampling comparator CMP1 and zero-crossing sampling comparator CMP2, or the driver module 16, amplifier circuit 15, and average value sampling circuit 14 to be integrated into the MCU / DSP chip.

[0027] This invention utilizes the characteristic that the inductive current of inductor L1 does not change abruptly to control the current. Furthermore, the average value sampling circuit 14 samples the average value of the electrical signal of inductor L1 in real time to obtain a third sampling signal, and sends the third sampling signal to an error comparator to compare it with a preset reference signal to generate an error signal. The digital processor adjusts the first reference Vref1 and the second reference Vref2 according to the error signal to reduce the error signal, so that the error signal tends to zero, thereby realizing closed-loop control of real-time detection and adjustment of the output current, achieving a precise digital closed-loop control effect. 1. Compared to traditional control systems that enter DCM discontinuous mode at low current, this invention, because inductor L1 operates in frequency conversion continuous mode throughout, ensures that the power supply remains in critical continuous mode even when dimmed to low current. This reduces EMI interference, decreases flicker coefficient at low current, and improves power supply performance. 2. The key feature of this invention is its utilization of the hardware functions of the main control module 10 (sampling comparator, error comparator, and brake reset function), eliminating the need for software intervention in cycle-by-cycle current control. This significantly reduces the clock frequency requirements of the main control module 10, thereby significantly lowering its cost and achieving a cost comparable to analog control chips. Furthermore, by combining the data processing capabilities of a digital processor, a precise digital control closed loop is achieved, reducing the complexity of digital systems and paving the way for the widespread application of digital control power supplies. It also supports the input of various digital and analog control signals (existing analog chips only support PWM and analog control signals).

[0028] This invention can be used in both low-voltage and high-voltage buck constant current power supplies. Besides lighting power supplies, it can also be used in all other buck switching power supplies.

[0029] It will be readily understood by those skilled in the art that the above preferred methods can be freely combined and superimposed without conflict.

[0030] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. A low-cost power supply circuit, characterized in that, include: The system comprises a main control module (10), a switch module (11), an inductor L1, and a sampling module. The switch module (11) is electrically connected to one end of the inductor L1, and the other end of the inductor L1 is electrically connected to the sampling module. When the inductor L1 is charging, the sampling module samples the peak value of the electrical signal of the inductor L1 to obtain a first sampling signal, and sends the first sampling signal to the main control module (10) for comparison with a first reference Vref1. When the first sampling signal exceeds the first reference Vref1, the sampling comparator generates a braking signal to turn off the switch module (11), causing the inductor L1 to start discharging. The sampling module samples the peak value of the electrical signal of the inductor L1. The electrical signal obtains a second sampling signal and sends the second sampling signal to the main control module (10) to compare with the second reference Vref2. When the second sampling signal is lower than the second reference Vref2, the sampling comparator sends a reset signal to turn on the switch module (11) so that the inductor L1 starts charging. The sampling module samples the average value of the electrical signal of the inductor L1 in real time to obtain a third sampling signal and sends the third sampling signal to the main control module to compare with a preset reference signal to generate an error signal. The main control module adjusts the first reference Vref1 and the second reference Vref2 according to the error signal to reduce the error signal.

2. The low-cost power supply circuit according to claim 1, characterized in that: The sampling module includes a sampling circuit (13) and an average value sampling circuit (14). The sampling circuit is used to sample the peak value of the electrical signal of the inductor L1, and the average value sampling circuit samples the average value of the electrical signal of the inductor L1.

3. The low-cost power supply circuit according to claim 2, characterized in that: It also includes a rectifier filter module (17), the input terminal of which is electrically connected to the output terminal of the inductor L1, and the output terminal of which is electrically connected to the sampling circuit (13) and the average value sampling circuit (14); or, the output terminal of the rectifier filter module (17) is electrically connected to the sampling circuit (13), and the average value sampling circuit (14) is electrically connected to the output terminal of the inductor L1 and the input terminal of the rectifier filter module (17).

4. The low-cost power supply circuit according to claim 2, characterized in that: It also includes an amplifier circuit (15) for amplifying the first sampling signal and the second sampling signal. One end of the amplifier circuit (15) is electrically connected to the output terminal of the sampling circuit (13), and the other end of the amplifier circuit (15) is electrically connected to the input terminal of the main control module.

5. The low-cost power supply circuit according to claim 4, characterized in that: It also includes a drive module (16), the input terminal of which is electrically connected to the main control module (10), and the output terminal of which is electrically connected to the switch module (11). The brake signal / reset signal are used to control the drive module (16) to turn off / on the switch module (11).

6. The low-cost power supply circuit according to claim 5, characterized in that: The main control module (10) also includes a PWM controller. The brake signal and reset signal are respectively input to the PWM controller. The PWM controller controls the drive module (16) to turn off / on the switch module (11) according to the received brake signal / reset signal.

7. The low-cost power supply circuit according to claim 6, characterized in that: The sampling circuit (13) includes a sampling resistor Rs, the rectifier filter module (17) includes a capacitor Co, the switching module (11) includes a MOS transistor Q1 and a MOS transistor Q2, the gate of the MOS transistor Q1 is electrically connected to one output terminal of the driving module (16), the gate of the MOS transistor Q2 is electrically connected to the other output terminal of the driving module (16), the drain of the MOS transistor Q1 is connected to the positive terminal of the power supply Vin, the source of the MOS transistor Q1 is electrically connected to the drain of the MOS transistor Q2 and one end of the inductor L1, the other end of the inductor L1 is electrically connected to one end of the capacitor Co, the other end of the capacitor Co is electrically connected to one end of the sampling resistor Rs, the input terminal of the amplifier circuit (15) and the input terminal of the average value sampling circuit (14), and the other end of the sampling resistor Rs and the source of the MOS transistor Q2 are grounded.

8. The low-cost power supply circuit according to claim 5, characterized in that: The average value sampling circuit (14), the driving module (16), the amplification circuit (15) and the main control module (10) are integrated into a single MCU / DSP chip.

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