Switching power supply circuit suitable for motor power supply

Abstract

The utility model discloses a switching power supply circuit suitable for motor power supply, which comprises a commercial power input rectification filter circuit, a starting circuit, a PWM chip, a field effect transistor, a transformer, a voltage stabilizing circuit and an output current limiting control circuit, when the switching power supply is started, the PWM chip obtains working voltage when U1 is started through the starting circuit, and when the output PWM chip and the field effect transistor work, the voltage stabilizing circuit outputs the working voltage when U1 is started. A secondary side main working winding of the transformer outputs controlled motor working voltage, due to the fact that current is large when the motor is started, output current is set and controlled by a related circuit of U3 according to the maximum working current of the motor, and after the motor works normally, a primary side power supply winding of the transformer supplies power to a PWM chip. In this way, it is guaranteed that the motor is started at the maximum working current, the switching power supply does not enter short-circuit protection due to too large output current, and starting and working of the circuit enter a good state.

Description

Technical Field

[0001] The utility model relates to a motor power supply, in particular to a switching power supply circuit suitable for motor power supply. Background Art

[0002] In the field of motor power supply circuits, with the advancement and widespread application of motor technology, traditional power supply designs have gradually exposed many defects, especially in motor starting, operating stability and protection mechanisms.

[0003] For example, when a motor is started, a large starting current is usually generated at the moment of starting due to the need to overcome static friction and rotational inertia. This current peak is often several times or even more than ten times the rated current of the motor, posing a huge challenge to the power supply system. The power supply design in the existing technology is often difficult to effectively cope with this transient high current impact, resulting in the following problems: PWM chip overload protection triggering: When the starting current exceeds the carrying capacity of the PWM chip, the chip's overload protection mechanism will be triggered, causing the PWM chip to stop working or enter a protection state, thereby affecting the normal starting and subsequent operation of the motor. Power supply voltage fluctuation: Large current impacts will also cause a momentary drop in the power supply voltage, which not only affects the starting performance of the motor, but may also have an adverse effect on other devices in the same power supply network. Shortened equipment life: Frequent overloads and voltage fluctuations will accelerate the aging of internal components of the power supply and shorten the service life of the equipment.

[0004] Of course, although some solutions have been proposed in the existing technology to address the above problems, such as adding a soft-start circuit, optimizing the PWM control algorithm, and increasing the power supply capacity, these solutions still have limitations in practical applications:

[0005] Increased cost: Adding a soft-start circuit or increasing the power supply capacity will significantly increase the system cost, which is not conducive to the market competitiveness of the product.

[0006] Increased complexity: Optimizing the PWM control algorithm requires complex programming and debugging, which increases the complexity of system design and the development cycle.

[0007] Limited effectiveness: Some solutions may be effective under specific conditions, but their effectiveness may be greatly reduced in complex and changing actual application scenarios. Summary of the Invention

[0008] The technical problem to be solved by the embodiments of the present invention is to provide a switching power supply circuit suitable for powering a motor, which can provide reliability and stability to the power supply of the motor by optimizing the power supply design.

[0009] In order to solve the above technical problems, the embodiment of the present utility model provides a switching power supply circuit suitable for motor power supply, including a mains input rectifier filter circuit, a start-up circuit, a PWM chip, a field effect tube, a transformer, a voltage stabilizing circuit, and an output current limiting control circuit. The output voltage of the mains input rectifier filter circuit is connected in series with the drain of the field effect tube through the primary side winding of the transformer, and the gate of the field effect tube is connected to the output end of the PWM chip. The start-up circuit includes a resistor unit and an energy storage capacitor connected in series at both ends of the output voltage. The energy storage capacitor and the primary side power supply winding of the transformer are connected to the P The power supply end of the WM chip is electrically connected, the secondary side main working winding of the transformer serves as the motor power supply output, the voltage stabilizing circuit includes an optocoupler, the input end of the optocoupler is connected to the motor power supply output, and the output end is connected to the voltage stabilizing end of the PWM chip, the output current limiting control circuit includes a current detection resistor and an amplifier, the current detection resistor is connected in series to the motor power supply output, the inverting end of the amplifier obtains a sampling signal from the current detection resistor and compares it with the first reference voltage on the non-phase end, and its output end is connected in series with the input end of the optocoupler, and the optocoupler is connected to a second reference voltage.

[0010] A preferred solution is that the resistance unit includes three resistors connected in series.

[0011] A preferred solution is that the primary-side power supply winding is electrically connected to the power supply end of the PWM chip via a series resistor R6 and a rectifier diode D2.

[0012] A preferred solution is that the secondary side main working winding of the transformer has an output rectifier and filter circuit.

[0013] A preferred solution is that the voltage stabilizing circuit also includes a voltage divider resistor unit connected to the motor power supply output, and a three-terminal voltage regulator connected in series with the optocoupler input end and the ground end, and the reference end of the three-terminal voltage regulator and the voltage divider resistor unit obtain the second reference voltage.

[0014] A preferred solution is that a diode D6 and a resistor R26 are connected in series to the output end of the amplifier, and the anode of the diode D6 is connected between the optocoupler and the three-terminal regulator.

[0015] Preferably, the current limiting control circuit includes a voltage regulator connected to the non-inverting terminal of the amplifier, and the voltage regulator provides the first reference voltage.

[0016] The implementation of the embodiments of the present utility model has the following beneficial effects: the present utility model can start with the maximum working current when the motor starts, avoiding the switching power supply entering short-circuit protection due to excessive output current, so that the circuit enters a good working state after startup, and can output PWM signals normally after the circuit enters the normal working state, so that the motor can work stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall circuit structure of the utility model. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. In the following paragraphs, the present invention is described in more detail by way of example with reference to the drawings. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are for the purpose of describing specific embodiments only and are not intended to limit this invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] like Figure 1 The circuit schematic diagram shown in FIG. 1 is used as the basis for implementing the present embodiment. Specifically, the present embodiment includes a mains input rectifier filter circuit, a startup circuit, a PWM chip, a field effect transistor, a transformer, a voltage stabilizing circuit, and an output current limiting control circuit.

[0022] Specifically, the AC input rectifier and filter circuit is composed of AC power ACL and ACN passing through the fuse F1 and the anti-surge thermistor RT1, and then reaching the common mode filter composed of capacitors C1 and LF1, and then rectified by the rectifier bridge DB1 and filtered by capacitor C2 to obtain a DC voltage.

[0023] The positive electrode of the DC voltage obtained above is connected to the ground after passing through the primary winding T1A of the transformer, the field effect transistor Q1, and the current detection resistor R11.

[0024] The current feedback terminal of the PWM chip U1 is connected to the current detection resistor R11 at the source of the field effect transistor Q1.

[0025] The startup circuit includes a resistance unit and a storage capacitor C3 connected in series at both ends of the output voltage. The resistance unit is composed of R3, R4, and R5 connected in series. The positive end of the voltage input is connected to the power input end of the PWM chip U1 through the startup resistors R3, R4, R5 and the storage capacitor C3.

[0026] The gate of the field effect transistor Q1 is connected to the output end of the PWM power supply chip through the resistor R8 and the diode D3.

[0027] The primary side of the transformer also includes a primary side power supply winding T1B, and the secondary side main working winding T1C of the transformer is connected to the motor load as the motor power supply output.

[0028] The primary side power supply winding T1B is electrically connected to the power supply terminal of the PWM chip via a series resistor R6 and a rectifier diode D2.

[0029] The secondary side main working winding of the transformer has an output rectifier and filter circuit, which includes an output rectifier diode D4, peak absorption components C8, R14, R15 and output filters C15, C16, C17. R37 is a dummy load.

[0030] The voltage stabilization circuit includes an optocoupler. The input terminal PC1A of the optocoupler is connected to the motor power supply output through a resistor R23 and is connected in parallel with a resistor R25. The output terminal PC1B of the optocoupler is connected to the voltage stabilization terminal of the PWM chip U1. The input terminal PC1A of the optocoupler and the ground terminal are connected in series with a three-terminal voltage regulator U2. The reference terminal of the three-terminal voltage regulator U2 is connected to a voltage divider resistor unit. The voltage divider resistor unit consists of resistors R16, R17, R18, and R19 connected in parallel to the motor power supply output. Resistors R18 and R19 are connected in parallel and connected to the reference terminal of the three-terminal voltage regulator U2. The three-terminal voltage regulator U2 provides a second reference voltage for the input terminal PC1A of the optocoupler.

[0031] The output current limit control circuit includes a current detection resistor R20 and an amplifier U3. The current detection resistor R20 is connected in series to the motor power output loop. The inverting terminal of the amplifier U3 obtains a sampling signal from the current detection resistor R20 through a resistor R28 and compares it with a first reference voltage on the non-inverting terminal. The output terminal of the amplifier U3 is connected in series with the input terminal PC1A of the optocoupler. Specifically, the output terminal of the amplifier U3 is connected in series with a diode D6 and a resistor R26. The anode of the diode D6 is connected between the input terminal PC1A of the optocoupler and the three-terminal regulator U2.

[0032] A voltage regulator U4 is connected to the non-inverting end of the amplifier to provide a first reference voltage for the amplifier U3. The voltage regulator U4, resistor R30, and capacitor C11 form a precise and stable reference voltage source. Resistors R29, R31, and R33 divide the reference voltage and apply it to the non-inverting input end of the amplifier U3.

[0033] In this embodiment, the voltage stabilization control process is as follows: when the output voltage of R16, R17, R18, and R19 increases, the voltage at the connection point of R16, R18, and U2 also increases, the current flowing through the input terminal PC1A of the optocoupler increases, and the phototransistor at the output terminal PC1B of the optocoupler is turned on, thereby pulling down the voltage at pin 2 of the PWM chip U1. The reduced voltage at pin 2 of the PWM chip U1 adjusts the duty cycle of the field-effect transistor Q1. As the duty cycle of the field-effect transistor Q1 decreases, the output voltage of the secondary side main working winding also decreases, and vice versa. This ensures the stability of the output voltage.

[0034] The current control process of this embodiment is as follows: Controlling the stable maximum output current is composed of D6, R20, R26, R27, C10, R28, R29, R30, R31, R33, U3, and U4. U4, R30, and C11 form a precise and stable reference voltage source. R29, R31, and R33 divide the reference voltage and apply it to the non-inverting input terminal of amplifier U3. When the motor is operating, current flows through resistor R20, generating a voltage across it. This voltage is fed to the inverting input of amplifier U3, where it is compared with the reference voltage at the non-inverting input, resulting in error amplification. When the voltage at U3's inverting input is higher than the voltage at the non-inverting input, amplifier U3's output goes low, increasing the current flowing through optocoupler PC1A through D6 and R26. Optocoupler PC1B conducts, lowering the voltage at pin 2 of PWM chip U1. This reduced voltage at pin 2 adjusts the duty cycle of field-effect transistor Q1. This lowers the voltage at the output, reducing the output current. This ensures that the load current never exceeds the set value. Adjusting the reference voltage at the non-inverting input of amplifier U3 or the resistance of current sampling resistor R20 can modify the maximum output current.

[0035] When the motor is turned on, the PWM chip stores energy through the starting resistors R3, R4, R5 and capacitor C3 to provide the working voltage for the PWM chip U1 when it starts. Because the starting current of the motor is large when it is turned on, the output voltage of the primary side power supply winding T1B and the secondary side main working winding T1C is low. The working voltage of the PWM chip U1 is provided by the starting resistors R3, R4, R5 and capacitor C3, so that the motor starts normally.

[0036] This embodiment uses the OB2263 PWM chip and an N-channel enhancement-mode MOSFET. The maximum motor operating current is determined by the voltage at pin 5 of U3 and the resistance value of R20. This limits the maximum output current of the motor power supply. Even in the event of an output short circuit, the power supply's input power consumption remains minimal due to the extremely low output voltage and maximum output current. This allows the motor to be started while also providing the switching power supply's short-circuit protection.

[0037] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A switching power supply circuit suitable for powering a motor, characterized in that: The invention comprises a mains input rectifier and filter circuit, a start-up circuit, a PWM chip, a field effect transistor, a transformer, a voltage stabilizing circuit, and an output current limiting control circuit. The output voltage of the mains input rectifier and filter circuit is connected in series with the drain of the field effect transistor through the primary winding of the transformer, and the gate of the field effect transistor is connected to the output end of the PWM chip. The start-up circuit comprises a resistor unit and an energy storage capacitor connected in series with both ends of the output voltage. The energy storage capacitor and the primary power supply winding of the transformer are electrically connected to the power supply end of the PWM chip. The secondary main working winding of the transformer serves as the motor power supply output. The voltage stabilizing circuit comprises an optocoupler, the input end of the optocoupler is connected to the motor power supply output, and the output end is connected to the voltage stabilizing end of the PWM chip. The output current limiting control circuit comprises a current detection resistor and an amplifier. The current detection resistor is connected in series to the motor power supply output. The inverting end of the amplifier obtains a sampling signal from the current detection resistor and compares it with a first reference voltage on the non-phase end. The output end of the amplifier is connected in series with the input end of the optocoupler, and the optocoupler is connected to a second reference voltage.

2. The switching power supply circuit suitable for motor power supply according to claim 1, characterized in that: The resistance unit includes three resistors connected in series.

3. The switching power supply circuit suitable for motor power supply according to claim 1, characterized in that: The primary-side power supply winding is electrically connected to the power supply terminal of the PWM chip via a series resistor R6 and a rectifier diode D2.

4. The switching power supply circuit suitable for powering a motor according to claim 1, characterized in that: The secondary side main working winding of the transformer is provided with an output rectification and filtering circuit.

5. The switching power supply circuit suitable for motor power supply according to claim 4, characterized in that: The voltage stabilization circuit also includes a voltage divider resistor unit connected to the motor power supply output, and a three-terminal voltage regulator connected in series with the optocoupler input terminal and the ground terminal. The reference terminal of the three-terminal voltage regulator and the voltage divider resistor unit obtain the second reference voltage.

6. The switching power supply circuit suitable for powering a motor according to claim 5, characterized in that: A diode D6 and a resistor R26 are connected in series to the output terminal of the amplifier. The anode of the diode D6 is connected between the input terminal PC1A of the optocoupler and the three-terminal regulator.

7. The switching power supply circuit suitable for powering a motor according to claim 6, characterized in that: The current limit control circuit further includes a voltage regulator connected to the non-inverting terminal of the amplifier, and the voltage regulator provides the first reference voltage.

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