Direct current motor speed regulation circuit

Abstract

The utility model relates to the technical field of motor speed regulation, in particular to a direct current motor speed regulation circuit. The speed regulation circuit comprises an input connector CON1 used for accessing a DC input voltage; the output connector CON2 is used for connecting a direct current motor; the step-down chip ME3148 is used for converting the direct-current input voltage into adjustable output voltage, and the step-down chip comprises a VI N pin 8, an SW pin 2, an FB pin 4, a VC pin 7, a CS pin 5 and a GND pin 3. The direct-current motor speed regulation control circuit is simple in structure, can realize wide-range and high-precision speed regulation control only by adjusting a single potentiometer, has the characteristics of low cost and high reliability while ensuring the speed regulation performance, and is suitable for direct-current motor control scenes with higher requirements on speed regulation range and precision.

Description

Technical Field

[0001] This utility model relates to the field of motor speed control technology, specifically a DC motor speed control circuit. Background Technology

[0002] DC motor speed control technology has wide applications in industrial control and consumer electronics. Traditional speed control methods mainly include armature circuit resistance adjustment, thyristor phase-shift speed control, and pulse width modulation (PWM) speed control. Among these, armature circuit resistance adjustment suffers from low efficiency and limited speed range; while thyristor phase-shift speed control can achieve a wider speed range, it generates significant electromagnetic interference and noise; and although PWM speed control has high efficiency, its circuit structure is complex and costly. Existing technologies using DC-DC step-down chips for speed control, while addressing these issues to some extent, still suffer from limitations such as limited output voltage adjustment range, insufficient adjustment accuracy, and poor circuit stability. Especially in applications requiring wide-range, high-precision speed control, existing solutions struggle to simultaneously meet the multiple requirements of continuously adjustable output voltage, low-noise operation, and high-efficiency conversion. Utility Model Content

[0003] This invention provides a DC motor speed control circuit to develop a DC motor speed control circuit that is simple in structure, has a wide adjustment range, high precision, and stable operation.

[0004] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0005] A DC motor speed control circuit is provided, the speed control circuit comprising:

[0006] Input connector CON1 is used to connect a DC input voltage;

[0007] Output connector CON2 is used to connect a DC motor;

[0008] The step-down chip ME3148 is used to convert the DC input voltage into an adjustable output voltage. The step-down chip includes a VIN pin 8, a SW pin 2, an FB pin 4, a VC pin 7, a CS pin 5, and a GND pin 3.

[0009] Potentiometer RP1 has its fixed end connected to pin 4 of the step-down chip and to the first pin of the output connector CON2 via resistor R1, and its sliding end grounded via resistor R2. The second pin of the output connector CON2 is also grounded.

[0010] The input capacitor C1 is connected between the first and second pins of the input connector CON1.

[0011] The output capacitor C2 is connected between the first pin of the output connector CON2 and ground.

[0012] Capacitors C3 and C4 are connected in series between the VC pin 7 and ground, and the VIN pin 8 is connected between the capacitors C3 and C4. The CS pin 5 is grounded.

[0013] Diode D1 has its cathode connected to pin 2 of the step-down chip and its anode connected to the first pin of the output connector CON2 via capacitor C5.

[0014] Inductor L1 is connected between the SW pin 2 of the step-down chip and the first pin of the output connector CON2;

[0015] Switch S1 is connected in series between the second pin of the input connector CON1 and the VIN pin 8 of the step-down chip, and the first pin of the input connector CON1 is grounded.

[0016] Furthermore, the potentiometer RP1 is a linearly adjustable resistor, used to change the feedback voltage of the step-down chip ME3148 by adjusting the position of the sliding end, so as to continuously adjust the output voltage and ensure that the output voltage is adjustable in the range of 5V-35V.

[0017] Furthermore, resistors R1 and R2 form a voltage divider network to set the reference feedback voltage of the step-down chip ME3148, and work with potentiometer RP1 to determine the adjustment range and accuracy of the output voltage.

[0018] Furthermore, the diode D1 is a Schottky diode, used to provide a freewheeling path for the inductor L1 during the turn-off period of the switch of the step-down chip ME3148, in order to prevent high voltage spikes and reduce switching losses.

[0019] Furthermore, the inductor L1 is a power inductor used to store and release energy during the switching cycle of the step-down chip ME3148, convert the voltage to a step-down, and simultaneously smooth the output current with the output capacitor C2 to reduce ripple.

[0020] Furthermore, the input capacitor C1 and the output capacitor C2 are electrolytic capacitors used to filter out low-frequency noise and provide energy storage; the capacitors C3 and C4 are MLCC capacitors used to filter out high-frequency noise to improve the transient response capability of the circuit.

[0021] Furthermore, the step-down chip ME3148 is a constant voltage or constant current step-down DC-DC converter that uses internal PWM to control the duty cycle of the switching transistor to convert voltage and control current.

[0022] The beneficial effects of this utility model are:

[0023] This invention effectively solves the technical problems existing in the prior art by using a feedback network composed of an ME3148 step-down chip and a precision potentiometer. Specifically, through an adjustable voltage divider network composed of potentiometer RP1 and resistors R1 and R2, continuous and precise adjustment of the output voltage within the range of 5V-35V is achieved, expanding the speed regulation range and improving the adjustment accuracy. The built-in PWM control mechanism of the ME3148 step-down chip, together with the external power inductor L1 and freewheeling diode D1, ensures efficient energy conversion and stable output voltage, while reducing switching noise. The filter network composed of input capacitor C1 and output capacitor C2 effectively suppresses voltage ripple at the input and output terminals, while the high-frequency filter network composed of C3 and C4 further improves the transient response capability of the circuit. This invention has a simple circuit structure, achieving wide-range and high-precision speed regulation control by adjusting only a single potentiometer. While ensuring speed regulation performance, it features low cost and high reliability, making it suitable for DC motor control scenarios with high requirements for speed regulation range and accuracy. Attached Figure Description

[0024] Figure 1 This is the circuit diagram of this utility model;

[0025] Figure 2 This is a schematic diagram of the PCB layout of this utility model. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0030] The present invention provides the following preferred embodiments:

[0031] To address the technical problems of limited voltage regulation range, insufficient output stability, and poor electromagnetic interference suppression in practical applications of DC motor speed control circuits, this embodiment provides a DC motor speed control solution based on the ME3148 buck chip, such as... Figure 1 and Figure 2 As shown. This utility model achieves more stable motor drive performance by optimizing the power path design, improving the feedback control mechanism, and strengthening the filter network configuration. The implementation methods of each technical feature and their interaction relationships will be described in detail below.

[0032] In this embodiment, the input connector CON1 uses a standard DC power interface, and its positive terminal is connected to the VIN pin 8 of the step-down chip ME3148 via switch S1. Switch S1 is a rocker switch with a rated current of 10A, and its contact material is silver alloy plated to ensure contact reliability under frequent operation. The input capacitor C1 is a 100μF / 50V electrolytic capacitor, connected in parallel between the positive terminal of CON1 and ground, used to filter out low-frequency ripple in the input voltage. The first ceramic capacitor C3 is a 0.1μF / 50V MLCC capacitor, also connected in parallel between the positive terminal of CON1 and ground, used to suppress high-frequency noise. It should be understood that this parallel configuration of the filtering network can cover a wide bandwidth of noise from low to high frequencies, ensuring the purity of the input voltage.

[0033] Furthermore, at the circuit input, the first pin of the input connector CON1 is directly connected to system ground, and the second pin forms a connection path with the VIN pin 8 of the step-down chip ME3148 through a mechanical switch S1. This switch is a rocker switch with a rated current of 10A, and its silver alloy contacts ensure long-term reliability. The input filter network consists of an electrolytic capacitor C1, which is connected between the two pins of CON1. ​​Its 100μF capacitance and low ESR effectively suppress voltage fluctuations at the input.

[0034] Furthermore, the buck converter section is implemented using the ME3148 chip. A series capacitor C3 and C4 are connected between the chip's VC pin 7 and system ground, forming a voltage divider network. Notably, the VIN pin 8 is directly connected to the midpoint of these two capacitors; this unique connection effectively improves the stability of the chip's internal reference voltage. The chip's CS pin 5 and GND pin 3 are reliably grounded, ensuring consistent signal reference levels. The power switching signal is output from SW pin 2 and transmitted to the output terminal through the power inductor L1.

[0035] Furthermore, the freewheeling circuit design employs a combination of a Schottky diode D1 and a ceramic capacitor C5. The cathode of diode D1 is directly connected to pin 2 of the SW circuit, while the anode is connected to the output terminal via a 10nF capacitor C5. This configuration not only fulfills the conventional freewheeling function but also effectively absorbs high-frequency noise during the switching process through capacitor C5, reducing electromagnetic interference at the output terminal by more than 12dB in actual measurements.

[0036] Furthermore, the output circuit employs a two-stage filtering design, using a large-capacity electrolytic capacitor C2 in parallel with a ceramic capacitor exhibiting excellent high-frequency characteristics to form the output filtering network. The first pin of the output connector CON2 receives the filtered DC voltage, while the second pin is directly grounded, forming a complete circuit. This design allows the output voltage ripple to be controlled below 50mVpp under rated load conditions.

[0037] Furthermore, the voltage feedback system employs a precision resistor network in conjunction with a multi-turn potentiometer. The first fixed terminal of potentiometer RP1 is connected to pin 4 of FB, the second fixed terminal is connected to the output terminal through a 24kΩ precision resistor R1, and the sliding terminal is grounded through a 1kΩ resistor R2. This direct feedback structure avoids the efficiency loss caused by traditional pre-regulator circuits, and actual measurements show that the voltage regulation linearity reaches over 99.5%.

[0038] During circuit operation, the input DC voltage is fed into the ME3148 chip after being switched on and off by switch S1. The chip's internal PWM controller automatically adjusts the pulse width output from pin SW based on the feedback voltage detected by pin FB4. The Buck topology, composed of power inductor L1 and freewheeling diode D1, converts the input voltage into an adjustable output voltage, which is supplied to the DC motor via CON2. Adjusting potentiometer RP1 changes the feedback voltage, thus achieving continuous and precise adjustment of the output voltage within the range of 5-35V.

[0039] Furthermore, in terms of thermal management, the exposed pads of the ME3148 chip are connected to the underlying copper foil through multiple thermal vias. Combined with a well-planned component layout, this ensures that the chip junction temperature does not exceed 85°C under full load. The power inductor and freewheeling diode are arranged orthogonally, reducing magnetic coupling interference and creating an effective natural convection heat dissipation channel.

[0040] Furthermore, the implementation of this utility model fully considers the reliability requirements in industrial environments. The PCB trace width for all high-current paths is no less than 2mm, and critical signal lines are grounded. The grounding system adopts a star connection, effectively avoiding ground loop interference. After rigorous testing, this solution demonstrates excellent performance in electromagnetic compatibility, conversion efficiency, and output voltage stability, fully meeting the application requirements of industrial-grade DC motor speed control.

[0041] This embodiment achieves high-performance DC motor speed control through optimized circuit topology and component parameters. The synergistic effect of various technical features gives the circuit significant advantages in terms of adjustment accuracy, output stability, and electromagnetic compatibility, making it promising for broad applications and market value. In practical applications, relevant parameters can be adjusted according to specific needs; for example, increasing the output capacitor capacitance can further reduce ripple, and selecting higher-precision resistors can improve adjustment resolution.

[0042] The circuit protection system in this embodiment includes multiple levels of protection. An overvoltage protection element is provided at the input terminal to absorb transient high-voltage pulses from the power grid. A reverse current blocking circuit is configured at the output terminal to prevent reverse current generated during motor power generation from damaging the power module. A precise current sampling network is provided at the current detection pin of the control chip to monitor load current changes in real time. It is understood that these protection measures effectively improve the safety and reliability of the system.

[0043] The operation of this embodiment is as follows: When the input voltage is connected through CON1, it is switched on and off by switch S1, and then the ME3148 chip performs step-down conversion. By adjusting the position of the sliding end of potentiometer RP1, the feedback voltage at pin 4 of FB can be changed, thereby adjusting the output voltage value. Power inductor L1 and freewheeling diode D1 complete energy storage and release during the on and off periods of the switching transistor, realizing the voltage conversion function. The output filter network further smooths the output voltage and reduces the ripple coefficient.

[0044] The technical advantages of this embodiment are reflected in several aspects: optimized power path design reduces conduction losses, improved feedback control system enhances voltage regulation accuracy, and strengthened filter network configuration improves electromagnetic compatibility performance. The entire circuit adopts a modular design concept, with each functional unit relatively independent yet organically coordinated, resulting in good maintainability and scalability. Furthermore, this solution fully considers reliability requirements in industrial production environments, employing corresponding safeguards in component selection and process handling.

[0045] The implementation of this embodiment effectively solves the voltage regulation stability problem in DC motor speed control circuits, achieving more stable motor drive performance. The optimized design and synergistic effect of various technical features make this solution perform excellently in practical applications, demonstrating high practical value and promising prospects for widespread adoption.

[0046] The beneficial effects of this utility model are specifically reflected in the fact that the above description is only a preferred embodiment of this utility model and is not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A DC motor speed control circuit, characterized in that, The speed control circuit includes: Input connector (CON1) is used to connect DC input voltage; Output connector (CON2) is used to connect a DC motor; A step-down chip (ME3148) is used to convert the DC input voltage into an adjustable output voltage. The step-down chip includes a VIN pin (8), a SW pin (2), an FB pin (4), a VC pin (7), a CS pin (5), and a GND pin (3). The potentiometer (RP1) has its fixed end connected to the FB pin (4) of the step-down chip and the first pin of the output connector (CON2) through a resistor (R1), and its sliding end is grounded through a resistor (R2). The second pin of the output connector (CON2) is also grounded. An input capacitor (C1) is connected between the first and second pins of the input connector (CON1); The output capacitor (C2) is connected between the first pin of the output connector (CON2) and ground; Capacitors (C3) and (C4) are connected in series between the VC pin (7) and ground, and the VIN pin (8) is connected between the capacitors (C3) and (C4), and the CS pin (5) is grounded; The diode (D1) has its cathode connected to the SW pin (2) of the step-down chip, and its anode connected to the first pin of the output connector (CON2) via a capacitor (C5). An inductor (L1) is connected between the SW pin (2) of the step-down chip and the first pin of the output connector (CON2); A switch (S1) is connected in series between the second pin of the input connector (CON1) and the VIN pin (8) of the step-down chip, and the first pin of the input connector (CON1) is grounded.

2. The DC motor speed control circuit as described in claim 1, characterized in that, The potentiometer (RP1) is a linearly adjustable resistor used to change the feedback voltage of the step-down chip (ME3148) by adjusting the position of the sliding end, thereby continuously adjusting the output voltage to ensure that the output voltage is adjustable within the range of 5V-35V.

3. The DC motor speed control circuit as described in claim 1, characterized in that, The resistors (R1) and (R2) form a voltage divider network, which is used to set the reference feedback voltage of the step-down chip (ME3148), and together with the potentiometer (RP1), determines the adjustment range and accuracy of the output voltage.

4. The DC motor speed control circuit as described in claim 1, characterized in that, The diode (D1) is a Schottky diode, used to provide a freewheeling path for the inductor (L1) during the turn-off period of the switch of the buck chip (ME3148) to prevent high voltage spikes and reduce switching losses.

5. The DC motor speed control circuit as described in claim 1, characterized in that, The inductor (L1) is a power inductor used to store and release energy during the switching cycle of the step-down chip (ME3148), convert the voltage to a step-down, and smooth the output current with the output capacitor (C2) to reduce ripple.

6. The DC motor speed control circuit as described in claim 1, characterized in that, The input capacitor (C1) and output capacitor (C2) are electrolytic capacitors used to filter out low-frequency noise and provide energy storage; the capacitors (C3) and (C4) are MLCC capacitors used to filter out high-frequency noise to improve the transient response capability of the circuit.

7. The DC motor speed control circuit as described in claim 1, characterized in that, The step-down chip (ME3148) is a constant voltage or constant current step-down DC-DC converter that uses internal PWM to control the duty cycle of the switching transistor to convert voltage and control current.

Images