An ac-dc conversion circuit for a drive motor of a cell wall breaking machine
By combining a low-loss synchronous rectifier bridge and a PWM controller in the AC/DC conversion circuit of the blender's drive motor, the problems of heat loss caused by diode rectification and power instability caused by load changes are solved, achieving efficient and stable motor power supply and improving the reliability and adaptability of the equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG SHUNDE TUOHAO ELECTRONIC APPLIANCE CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-16
AI Technical Summary
In the existing AC/DC conversion circuit of the drive motor of the blender, there is a voltage drop of about 0.7V during the diode rectification process, which leads to a large amount of heat and power loss. Moreover, undervoltage or overvoltage is prone to occur when the load changes, making it difficult to achieve stable power supply.
The circuit design combines a low-loss synchronous rectifier bridge and a PWM controller. Power MOSFETs are used instead of diodes for rectification, and the duty cycle of the switching MOSFETs is adjusted by the PWM controller according to the voltage sampling signal to form a closed-loop feedback mechanism to ensure the stability of the DC input voltage of the motor.
It significantly reduces power loss and heat generation, improves the reliability and adaptability of the motor, ensures the stability and efficiency of motor power supply when the load changes, and extends the equipment life.
Smart Images
Figure CN122225866A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of conversion circuit technology, specifically relating to an AC / DC conversion circuit for a blender drive motor. Background Technology
[0002] A high-speed blender is a high-powered household or commercial food processing appliance that uses high-speed rotating blades to break down the cell walls of ingredients, releasing nutrients and improving food absorption. It's commonly used for making juice, soy milk, smoothies, or grinding hard ingredients like ice and nuts. The blender's motor is the driving unit, responsible for converting electrical energy into mechanical energy to power the high-speed rotating blades, performing tasks such as breaking down, blending, and chopping. The motor typically requires a stable DC voltage to ensure high-speed operation and load adaptability. The AC-DC converter circuit, also known as an AC-DC power rectifier circuit, is used to convert alternating current (AC) to direct current (DC). In a high-speed blender, it converts household mains power into stable DC power for the blender's operation.
[0003] AC / DC converters play a crucial role in modern electrical appliances and industrial equipment. They convert alternating current (AC) supplied by the power grid into direct current (DC) required by electronic components and DC motors, ensuring a stable and controllable power supply for efficient and safe operation. In kitchen appliances such as blenders, AC / DC converters not only ensure the drive motor operates smoothly at high speeds but also effectively reduce the impact of voltage fluctuations on the motor and control circuits, preventing overheating or damage. Simultaneously, they improve overall energy efficiency, extend equipment lifespan, and are an indispensable key component in ensuring equipment performance, reliability, and safety.
[0004] However, existing blender motor AC / DC conversion circuits typically use diodes. When current flows through them, during rectification, there is a voltage drop of approximately 0.7V, generating significant heat. This affects the equipment's operating environment, causing energy loss and disrupting the stable power supply to the blender motor. Furthermore, when the blender processes different materials, load variations can lead to voltage fluctuations, potentially causing undervoltage or overvoltage damage, making it difficult to achieve a stable power supply to the blender motor. Summary of the Invention
[0005] The purpose of this invention is to provide an AC / DC conversion circuit for a blender drive motor. This circuit addresses the problem of existing AC / DC conversion circuits for blender drive motors, which typically use diodes. When current flows through these diodes, a voltage drop of approximately 0.7V occurs during rectification, generating significant heat, affecting the equipment's operating environment, causing energy loss, and hindering stable power supply to the blender drive motor. Furthermore, the voltage fluctuates with load changes when the blender processes different materials, potentially leading to undervoltage or overvoltage damage, making it difficult to achieve stable power supply to the blender drive motor.
[0006] To solve the above-mentioned technical problems, the present invention provides an AC / DC conversion circuit for a blender drive motor.
[0007] First aspect This invention provides an AC / DC conversion circuit for a blender drive motor, comprising: a power input connector, a synchronous rectifier controller, a low-loss synchronous rectifier bridge with multiple power MOSFETs, a PWM controller, and a blender drive motor control sub-circuit with switching MOSFETs. The power input connector is connected to a low-loss synchronous rectifier bridge via a synchronous rectifier controller, wherein the low-loss synchronous rectifier bridge is used to perform low-loss rectification of the AC power passing through the power input connector. The low-loss synchronous rectifier bridge is connected to the PWM controller and the blender drive motor control sub-circuit, respectively. The blender drive motor control sub-circuit also includes a first sampling resistor and a second sampling resistor connected across the blender drive motor to sample the voltage of the blender drive motor and output a voltage sampling signal; Both the low-loss synchronous rectifier bridge and the PWM controller are connected to the blender drive motor control sub-circuit through switching MOSFETs; the PWM controller is used to control the duty cycle of the switching MOSFETs according to the voltage sampling signal. The PWM controller maintains a stable DC input voltage for the blender's drive motor by adjusting the duty cycle, thus preventing overvoltage or undervoltage in the blender's drive motor under different loads.
[0008] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, the entire process begins with the AC power input, driving a low-loss synchronous rectifier bridge via a synchronous rectifier controller. This bridge uses power MOSFETs instead of traditional diodes for rectification. Due to the extremely low on-resistance of the power MOSFETs, the voltage drop during rectification is significantly reduced, thereby significantly reducing power loss and heat generation, and improving the operating environment of the equipment. The rectified DC power supplies the PWM controller and the blender motor control sub-circuit. The latter detects the motor voltage in real time through a sampling resistor and feeds back the sampling signal. Based on this, the PWM controller dynamically adjusts the duty cycle of the switching MOSFETs. When the load changes (such as when processing different materials), it automatically maintains the stability of the motor's DC input voltage by adjusting the conduction time, avoiding undervoltage or overvoltage damage. The low-loss characteristics of synchronous rectification combined with the feedback mechanism of closed-loop PWM control: the low voltage drop of the power MOSFETs reduces rectification losses, while voltage sampling and duty cycle adjustment form a voltage stabilization closed loop, ensuring a constant output voltage. This achieves efficient and stable power supply to the blender motor, not only saving energy but also improving the motor's reliability and adaptability, effectively coping with load fluctuations. Attached Figure Description
[0009] Figure 1 This is a schematic diagram of the AC / DC conversion circuit for a blender drive motor provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the AC / DC conversion circuit for a blender drive motor provided in another embodiment of the present invention.
[0010] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0012] The AC / DC conversion circuit for the blender drive motor provided in this invention will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.
[0013] Example 1 Reference Figure 1 The diagram shows a schematic diagram of the AC / DC conversion circuit for a blender drive motor provided in an embodiment of the present invention.
[0014] Reference Figure 2The diagram shows a schematic of the AC / DC conversion circuit for a blender drive motor provided in an embodiment of the present invention.
[0015] This invention provides an AC / DC conversion circuit for a blender drive motor, comprising: The system includes a power input connector, a synchronous rectifier controller, a low-loss synchronous rectifier bridge with multiple power MOSFETs, a PWM controller, and a blender drive motor control sub-circuit with switching MOSFETs.
[0016] The power input connector is connected to a low-loss synchronous rectifier bridge via a synchronous rectifier controller. The low-loss synchronous rectifier bridge is used to perform low-loss rectification of the AC power passing through the power input connector.
[0017] This rectifier bridge structure ensures that current always flows through a low-impedance path, thereby reducing the on-state voltage drop. A synchronous rectifier controller detects the input phase and controls the turn-on timing of the MOSFETs in the upper and lower bridge arms respectively. The MOSFETs only turn on during their required half-cycle, avoiding cross-conduction or wasted power, further reducing power consumption.
[0018] The low-loss synchronous rectifier bridge is connected to the PWM controller and the blender drive motor control sub-circuit, respectively.
[0019] The blender drive motor control sub-circuit also includes a first sampling resistor and a second sampling resistor connected across the blender drive motor to sample the voltage of the blender drive motor and output a voltage sampling signal.
[0020] Both the low-loss synchronous rectifier bridge and the PWM controller are connected to the blender drive motor control sub-circuit via switching MOSFETs. The PWM controller controls the duty cycle of the switching MOSFETs based on the voltage sampling signal.
[0021] The PWM controller maintains a stable DC input voltage for the blender's drive motor by adjusting the duty cycle, thus preventing overvoltage or undervoltage in the blender's drive motor under different loads.
[0022] The power input connector H1 connects to the AC power supply, providing energy for the entire circuit. The synchronous rectifier controller controls the MOSFET switching sequence of the low-loss synchronous rectifier bridge according to the AC phase, ensuring current flows only through low-impedance paths, avoiding energy waste and cross-conduction. The low-loss synchronous rectifier bridge consists of multiple power MOSFETs, replacing traditional diode rectification. Its low on-resistance and negligible voltage drop reduce rectification losses and heat generation, achieving efficient AC-to-DC conversion. The PWM controller adjusts the on-time of the switching MOSFETs via duty cycle, enabling high-frequency regulation of the motor power supply, stabilizing the output voltage and adapting to load changes. The blender's drive motor control sub-circuit includes switching MOSFETs and sampling resistors, used to sample and control the motor voltage, forming a closed-loop feedback to ensure a constant DC voltage for the motor, allowing stable operation regardless of load variations.
[0023] The AC / DC conversion circuit of this blender's drive motor uses a synchronous rectifier controller to control a low-loss synchronous rectifier bridge, efficiently converting AC power into stable DC power. The low on-resistance of the power MOSFET significantly reduces rectified voltage drop and heat generation. The rectified DC power supplies the motor through a PWM controller and switching MOSFETs. A sampling resistor monitors the motor terminal voltage in real time and feeds it back to the PWM controller, which adjusts the duty cycle in a closed loop to keep the DC input voltage constant despite load changes. This mechanism, combining synchronous rectification and closed-loop PWM, not only improves energy efficiency but also ensures stable motor operation when processing different ingredients, preventing overvoltage or undervoltage damage, improving reliability and adaptability, and extending the equipment's lifespan.
[0024] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, the entire process begins with the AC power input, driving a low-loss synchronous rectifier bridge via a synchronous rectifier controller. This bridge uses power MOSFETs instead of traditional diodes for rectification. Due to the extremely low on-resistance of the power MOSFETs, the voltage drop during rectification is significantly reduced, thereby significantly reducing power loss and heat generation, and improving the operating environment of the equipment. The rectified DC power supplies the PWM controller and the blender motor control sub-circuit. The latter detects the motor voltage in real time through a sampling resistor and feeds back the sampling signal. Based on this, the PWM controller dynamically adjusts the duty cycle of the switching MOSFETs. When the load changes (such as when processing different materials), it automatically maintains the stability of the motor's DC input voltage by adjusting the conduction time, avoiding undervoltage or overvoltage damage. The low-loss characteristics of synchronous rectification combined with the feedback mechanism of closed-loop PWM control: the low voltage drop of the power MOSFETs reduces rectification losses, while voltage sampling and duty cycle adjustment form a voltage stabilization closed loop, ensuring a constant output voltage. This achieves efficient and stable power supply to the blender motor, not only saving energy but also improving the motor's reliability and adaptability, effectively coping with load fluctuations.
[0025] In one possible implementation, the low-loss synchronous rectifier bridge includes protection diodes connected to a first power MOSFET, a second power MOSFET, a third power MOSFET, and a fourth power MOSFET, respectively.
[0026] The anode of the protection diode is connected to the drain of the third power MOSFET and the drain of the fourth power MOSFET, respectively. The cathode of the protection diode is connected to the source of the first power MOSFET and the source of the second power MOSFET, respectively.
[0027] The low-loss synchronous rectifier bridge consists of multiple power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) used to efficiently convert alternating current (AC) to direct current (DC). Compared to traditional diode rectification, it has lower on-resistance and minimal voltage drop, reducing energy loss and heat generation. The power MOSFETs (Q1–Q4) control the current path of each bridge arm, precisely controlled by the synchronous rectifier controller to ensure current always flows along the low-impedance path. Protection diodes are connected to the power MOSFETs, with their anodes connected to the drain of the upper bridge arm MOSFET and their cathodes connected to the source of the lower bridge arm MOSFET. Their function is to prevent voltage spikes and reverse current from damaging the MOSFETs, providing a safe discharge path when the MOSFETs are off, and protecting the rectifier bridge for stable operation.
[0028] It should be noted that the low-loss synchronous rectifier bridge in this circuit achieves high-efficiency rectification through power MOSFETs. The power MOSFETs have extremely low on-resistance, greatly reducing rectified voltage drop and heat generation, and improving energy utilization. Protection diodes provide a safe discharge path in each bridge arm. When transient spikes occur in current direction or voltage fluctuations, the diodes conduct to release energy, preventing damage to the MOSFETs and maintaining voltage stability in the rectifier bridge. With this configuration, current always flows along a low-impedance path, resulting in high rectification efficiency and low heat generation. Simultaneously, it protects the circuit and motor load from overvoltage surges, achieving the goal of safe, stable, and efficient power supply for the blender's drive motor.
[0029] In one possible implementation, the power input connector includes a neutral input terminal and a live input terminal. The synchronous rectification controller includes pins IN1, IN2, TG1, TG2, BG1, BG2, EP, OUTP, and OUTN.
[0030] The gate of the first power MOSFET is connected to pin TG1. The drain of the first power MOSFET is connected to the live wire input. The gate of the first power MOSFET is connected to pin BG1. The drain of the first power MOSFET is connected to the neutral wire input. The gate of the third power MOSFET is connected to pin TG2. The source of the third power MOSFET is connected to the live wire input. The gate of the fourth power MOSFET is connected to pin BG2. The source of the fourth power MOSFET is connected to the neutral wire input.
[0031] The common connection point of the cathode of the protection diode, the source of the first power MOSFET, and the positive terminal of the source of the second power MOSFET is connected to the OUTP pin. The common connection point of the anode of the protection diode, the drain of the third power MOSFET, and the negative terminals of the source and drain of the fourth power MOSFET is connected to the OUTN pin and the EP pin, respectively.
[0032] The power input connectors (neutral and live wires) connect to the AC power supply, providing energy to the entire rectifier circuit. The neutral and live wires correspond to the two ends of the AC input, ensuring the rectifier bridge receives a complete voltage. The synchronous rectifier controller detects the phase of the input AC power and controls the turn-on timing of the power MOSFETs. The rectifier bridge, through low-impedance MOSFETs and synchronous control, ensures the current follows the path of least resistance while precisely controlling the turn-on timing, achieving efficient AC-to-DC conversion while reducing energy loss and heat, thus improving power supply efficiency and stability. The upper and lower bridge arm MOSFETs are driven by the TG and BG pins, respectively, ensuring current flows only in the appropriate half-cycle and avoiding cross-conduction. EP, OUTP, and OUTN are used to output DC power and provide a power loop reference. Power MOSFETs (Q1–Q4) form the core conductive components of the rectifier bridge, with the upper and lower bridge arms controlling the current direction. Precise turn-on by the synchronous controller achieves low-loss rectification. Protection diodes are connected in parallel with the MOSFETs to discharge voltage spikes and reverse current, preventing damage to the MOSFETs from high voltage while maintaining stable output DC power. The negative and positive common connection points are connected to the OUTP and OUTN pins, respectively, to enable the synchronous rectifier controller to monitor the rectified output.
[0033] It should be noted that in this circuit, AC power enters the rectifier system through the power input connector, with the neutral and live wires providing complete voltage to the rectifier bridge. The synchronous rectifier controller precisely drives the upper and lower bridge power MOSFETs according to the AC phase, ensuring current flows only along low-impedance paths while avoiding cross-conduction and energy waste. Protection diodes release transient voltage spikes when the MOSFETs are off, preventing device damage and stabilizing the output voltage. The rectified DC power is output through the common connection point, providing a stable power supply for the PWM control and the blender's drive motor. This configuration achieves efficient rectification, low heat loss, and voltage regulation, improving the blender's power supply reliability and motor adaptability, enabling the equipment to operate stably and efficiently even under varying loads.
[0034] In one possible implementation, the synchronous rectification controller is specifically the LT4320.
[0035] The first power MOSFET, the second power MOSFET, the third power MOSFET, and the fourth power MOSFET are specifically NCE65T180F.
[0036] The protection diode D1 is specifically an SMAJ440A.
[0037] Specifically, the synchronous rectifier controller U1 can be an LT4320. The first power MOSFET Q1, second power MOSFET Q2, third power MOSFET Q3, and fourth power MOSFET Q4 can all be NCE65T180F. The protection diode D1 can be an SMAJ440A to prevent voltage spikes. The neutral input and live input are AC_N and AC_L, respectively. This circuit configuration uses a synchronous controller to precisely drive low-impedance MOSFETs for rectification, combined with the protection diode to prevent voltage spikes, achieving efficient, low-heat, and stable DC power supply, ensuring safe and reliable motor operation.
[0038] When AC power is applied, the LT4320 (U1) acts like a smart traffic policeman. It monitors the phase of the AC input in real time. During the positive half-cycle, it outputs a high level to turn on Q1 and Q4; during the negative half-cycle, it turns on Q2 and Q3. Traditional rectifier bridges use diodes, which result in a voltage drop of approximately 0.7V when current flows through them, generating a significant amount of heat. In contrast, Solution A uses the NCE65T180F (Q1-Q4) with extremely low on-resistance and negligible voltage drop, thus solving the problem of "low efficiency and energy waste in traditional circuits" that you mentioned.
[0039] In one possible implementation, a bypass capacitor is connected between the OUTP and OUTN pins of the synchronous rectifier controller.
[0040] Optionally, the bypass capacitor C1 can be a 0.1μF capacitor. The bypass capacitor absorbs high-frequency interference at the rectifier output, smooths transient voltage fluctuations, and stabilizes the output DC power, thereby ensuring efficient and reliable operation of the subsequent circuits and motor.
[0041] In one possible implementation, the PWM controller includes a VFB pin, a VCC pin, an ISENSE pin, an OUT pin, and a GND pin.
[0042] Both the ISENSE and GND pins are connected to the negative common connection point. The VCC pin is connected to the positive common connection point through the third voltage divider resistor.
[0043] The PWM controller (VFB, VCC, ISENSE, OUT, GND pins) generates pulse width modulation signals to control the on-time of the switching MOSFETs, thereby regulating the output voltage and motor power supply. The ISENSE and GND pins are connected to the negative common point to detect circuit current, enabling overcurrent protection and feedback regulation. The VCC pin is connected to the positive common point through a voltage divider resistor, providing a stable reference voltage to the controller for adjusting the PWM duty cycle and maintaining a constant output voltage. The PWM controller generates pulse signals by sampling the current and reference voltage, adjusting the MOSFET duty cycle to achieve closed-loop voltage control, ensuring stable and efficient motor power supply and automatically adapting to load changes.
[0044] In one possible implementation, the PWM controller is specifically the UC3842.
[0045] Optionally, the PWM controller U4 can be a UC3842. The third voltage divider resistor R3 can be a 150K resistor.
[0046] It should be noted that in this circuit, the PWM controller uses UC3842, which generates high-frequency pulses based on voltage and current feedback signals, drives the switching MOSFET to regulate the current flow to the motor, and maintains stable output voltage through closed-loop control of the duty cycle, thereby achieving stable and efficient power supply to the motor and adapting to load changes, ensuring safe and reliable operation of the equipment.
[0047] In one possible implementation, the blender drive motor control sub-circuit includes a second voltage filter capacitor, a third voltage filter capacitor, a switching MOSFET, a freewheeling diode, an energy storage inductor, an output capacitor, a blender drive motor, a first sampling resistor, and a second sampling resistor.
[0048] The second voltage filter capacitor, the third voltage filter capacitor, the freewheeling diode, the energy storage inductor, the output capacitor, and the blender drive motor are all connected in parallel between the negative common connection point and the positive common connection point.
[0049] A switching MOSFET is connected in series between the third voltage filter capacitor and the freewheeling diode. An energy storage inductor is connected in series between the freewheeling diode and the output capacitor.
[0050] The first sampling resistor and the second sampling resistor are connected in series and then connected in parallel across the two ends of the blender's drive motor.
[0051] Optionally, the second voltage filter capacitor C2 can be 470μF, and the third voltage filter capacitor C3 can be 0.1μF. The switching MOSFET Q5 can also be an NCE65T180F MOSFET. The energy storage inductor L1 can be a 1mH inductor. The output capacitor C4 can be a 470μF capacitor. The blender drive motor is represented as U3 (M) in the diagram. Both the first sampling resistor R1 and the second sampling resistor R2 can be 10K resistors.
[0052] R1 and R2 are connected across the motor to sample the voltage, and the sampled signal is sent to the feedback pin of U4. If the blender is blending hard ice cubes, the increased motor load causes the output voltage to drop. U4 will immediately sense this and automatically increase the on-time (duty cycle) of Q5. This real-time adjustment ensures that the DC voltage across the motor remains at the set value regardless of whether the cup contains water or ice, avoiding the "overvoltage or undervoltage damage to the motor" you mentioned.
[0053] The second and third voltage filter capacitors are used to smooth the PWM output voltage, absorb high-frequency ripple, and provide stable DC power to the motor. The switching MOSFET, as a high-frequency switching device, quickly turns on and off according to the PWM signal to achieve energy transfer and voltage regulation. The freewheeling diode provides a current loop when the MOSFET is off, allowing the energy storage inductor to release energy for continuous power supply and preventing voltage drops. The energy storage inductor stores electrical energy and releases it through a magnetic field, achieving smooth current output and reducing the impact of current fluctuations on the motor. The output capacitor further smooths the DC output voltage, providing clean energy to the motor. The blender drive motor receives a stable DC power supply, enabling high-speed, high-load blending and pulverizing of ingredients. The first and second sampling resistors monitor the motor terminal voltage and feed the signal back to the PWM controller to form a closed-loop regulation, achieving voltage stability.
[0054] Although the rectified voltage is DC, its waveform resembles undulating mountains. The large capacitor C2 (470μF) smooths the pulsating voltage to approximately 311V (out of 220V) through its charging and discharging effect. 1.414) Stable DC bus power provides a clean energy pool for the motor.
[0055] It should be noted that the motor control sub-circuit of this blender smooths the DC power after PWM regulation through filter capacitors, energy storage inductors, and freewheeling diodes, minimizing output voltage and current fluctuations and thus providing stable energy to the motor. The switching MOSFETs rapidly turn on and off according to the PWM signal, precisely adjusting the energy to the motor. The first and second sampling resistors monitor the motor voltage in real time and feed it back to the PWM controller, forming a closed-loop control. This closed-loop regulation ensures that the motor input voltage remains constant regardless of load changes, guaranteeing safe and efficient operation of the blender under high-speed and heavy-load conditions, while reducing heat and energy loss, and improving overall reliability and lifespan.
[0056] The UC3842 (U4) generates a high-frequency pulse signal to drive Q5. Q5 switches at a rate of tens of thousands of times per second. When Q5 is on, energy is injected into inductor L1 and drives the motor; when Q5 is off, inductor L1 uses magnetic field energy to continue powering the motor through U2 (MUR1560).
[0057] In one possible implementation, the switching MOSFET is specifically an NCE65T180F field-effect transistor.
[0058] The freewheeling diode is specifically MUR1560.
[0059] It should be noted that the freewheeling diode U2 can be a MUR1560, allowing the inductor to release energy.
[0060] It should be noted that in this circuit, the switching MOSFET quickly turns on and off, injecting energy into the energy storage inductor. The freewheeling diode provides a current loop, allowing the inductor to release the stored energy to maintain the power supply to the motor. Combined with closed-loop control, this ensures stable output voltage, reduces fluctuations and energy loss, thereby achieving safe, efficient and stable operation of the blender motor.
[0061] In one possible implementation, the gate of the switching MOSFET is connected to the OUT pin. The source of the switching MOSFET is connected to a third voltage filter capacitor. The drain of the switching MOSFET is connected to the cathode of a freewheeling diode.
[0062] The VFB pin is connected between the first sampling resistor and the second sampling resistor.
[0063] The switching MOSFET's gate is connected to the OUT pin, which is also connected to the PWM controller's output. The gate receives pulse signals to control the MOSFET's on / off state, thus regulating the current. The MOSFET's source is connected to a third voltage filter capacitor, which provides a stable DC reference voltage and absorbs switching transients, smoothing voltage fluctuations. The MOSFET's drain is connected to the freewheeling diode's cathode. When the MOSFET is off, the freewheeling diode provides a loop, allowing the energy storage inductor to release energy for continuous power supply and preventing voltage drops. The VFB pin is connected between the first and second sampling resistors. These resistors monitor the motor terminal voltage and feed it back to the PWM controller to form a closed-loop regulation, keeping the output voltage constant.
[0064] It should be noted that in this circuit, the PWM controller outputs a pulse signal through the OUT pin to drive the switching MOSFET, controlling the energy injection into the energy storage inductor and maintaining continuous motor current through the freewheeling diode. A source-connected filter capacitor smooths voltage fluctuations and provides a stable reference voltage. The VFB pin monitors the DC voltage at the motor terminals through a sampling resistor and feeds it back to the PWM controller to form a closed-loop control. The PWM dynamically adjusts the MOSFET's on-time to keep the motor input voltage constant. This configuration achieves efficient, stable, and adaptive power supply to the blender motor, while reducing energy loss and voltage fluctuations, improving motor reliability and overall equipment performance.
[0065] In practical applications, the AC / DC conversion circuit of this blender's drive motor precisely controls the low-loss MOSFET rectifier bridge through a synchronous rectifier controller, efficiently converting AC power into stable DC power. The low on-resistance of the power MOSFETs significantly reduces rectified voltage drop and heat generation, improving energy utilization. The rectified DC power passes through a filter capacitor and a smoothing energy storage inductor, further stabilizing the voltage and current. The switching MOSFETs quickly turn on and off according to the pulse signal output by the PWM controller, precisely regulating energy to the motor. A sampling resistor monitors the motor terminal voltage in real time and feeds it back to the PWM controller to form a closed-loop regulation, maintaining a constant DC input voltage to the motor by dynamically adjusting the MOSFET duty cycle. This mechanism, combining synchronous rectification and closed-loop PWM control, not only ensures stable operation of the blender motor under different loads, preventing damage from overvoltage and undervoltage, but also reduces energy loss, heat generation, and improves power supply efficiency and motor reliability, ensuring the blender operates safely and efficiently under high-speed and high-load conditions.
[0066] More specifically, in the first stage, the rectification section, this part consists of U1 and Q1-Q4. The input current is approximately: The peak voltage is approximately: A traditional diode bridge, consisting of two diodes, has a voltage drop of approximately 2.0V and a power consumption of approximately [missing information]. The internal resistance of the power MOSFET in this scheme At any given time, two chips are conducting. The rectified power consumption is approximately: It can be seen that power consumption has decreased by about 60%. This means the circuit board temperature will decrease significantly. In the second stage, DC bus filtering is handled by C2. When C2 discharges at 100Hz (the rectified frequency), the voltage will fluctuate. At this time, the bus ripple voltage is approximately: The actual bus voltage range is: The average DC voltage is approximately 297V. This fluctuation is acceptable for voltage-driven circuitry because the subsequent Buck circuitry stabilizes it. In the third stage, the Buck converter bucks and regulates the voltage. To reduce the input voltage from approximately 297V to 150V, the duty cycle is approximately: The UC3842's switching frequency is typically set at 50kHz. The inductor ripple current is approximately: The average click current is 3.3A, and the ripple is 1.47A. The ripple factor is approximately 45%. Within a reasonable range, it can be seen that a 1mH inductor L1 is suitable. Using C4 for filtering, assuming the equivalent series resistance of the capacitor is 0.1Ω, the output voltage ripple is approximately: As can be seen, at an output of 150V, the ripple is only 0.15V, indicating an extremely clean power supply. Overall, the simulated rectification efficiency is approximately 99.2% (extremely high rectification efficiency, minimal heat generation). With an output voltage of 150DC, R1 needs to be corrected to 590kJ. The load regulation is less than 1% (voltage does not drop when encountering hard objects, remaining stable). The output ripple is less than 0.15V (very stable, with low motor noise).
[0067] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.
Claims
1. An AC / DC conversion circuit for a blender drive motor, characterized in that, include: Power input connector, synchronous rectifier controller, low-loss synchronous rectifier bridge with multiple power MOSFETs, PWM controller, and blender drive motor control sub-circuit with switching MOSFETs; The power input connector is connected to the low-loss synchronous rectifier bridge via the synchronous rectifier controller, wherein the low-loss synchronous rectifier bridge is used to perform low-loss rectification of the AC power passing through the power input connector. The low-loss synchronous rectifier bridge is connected to the PWM controller and the blender drive motor control sub-circuit, respectively. The blender drive motor control sub-circuit also includes a first sampling resistor and a second sampling resistor connected across the blender drive motor to sample the voltage of the blender drive motor and output a voltage sampling signal; Both the low-loss synchronous rectifier bridge and the PWM controller are connected to the blender drive motor control sub-circuit via the switching MOSFET; wherein, the PWM controller is used to control the duty cycle of the switching MOSFET according to the voltage sampling signal; The PWM controller maintains a stable DC input voltage for the blender drive motor by adjusting the duty cycle, thereby preventing overvoltage or undervoltage of the blender drive motor under different loads.
2. The AC / DC conversion circuit for the blender drive motor according to claim 1, characterized in that, The low-loss synchronous rectifier bridge includes protection diodes connected to the first power MOSFET, the second power MOSFET, the third power MOSFET, and the fourth power MOSFET, respectively. The anode of the protection diode is connected to the drain of the third power MOSFET and the drain of the fourth power MOSFET, respectively; the cathode of the protection diode is connected to the source of the first power MOSFET and the source of the second power MOSFET, respectively.
3. The AC / DC conversion circuit for the blender drive motor according to claim 2, characterized in that, The power input connector includes a neutral input terminal and a live input terminal; the synchronous rectifier controller includes IN1 pin, IN2 pin, TG1 pin, TG2 pin, BG1 pin, BG2 pin, EP pin, OUTP pin, and OUTN pin; The gate of the first power MOSFET is connected to the TG1 pin; the drain of the first power MOSFET is connected to the live wire input terminal; the gate of the first power MOSFET is connected to the BG1 pin; the drain of the first power MOSFET is connected to the neutral wire input terminal; the gate of the third power MOSFET is connected to the TG2 pin; the source of the third power MOSFET is connected to the live wire input terminal; the gate of the fourth power MOSFET is connected to the BG2 pin; the source of the fourth power MOSFET is connected to the neutral wire input terminal. The common connection point of the cathode of the protection diode, the source of the first power MOSFET, and the positive terminal of the source of the second power MOSFET is connected to the OUTP pin; the common connection point of the anode of the protection diode, the drain of the third power MOSFET, and the negative terminals of the source and drain of the fourth power MOSFET is connected to the OUTN pin and the EP pin, respectively.
4. The AC / DC conversion circuit for the blender drive motor according to claim 3, characterized in that, The synchronous rectifier controller is specifically the LT4320; The first power MOSFET, the second power MOSFET, the third power MOSFET, and the fourth power MOSFET are specifically NCE65T180F; The protection diode D1 is specifically an SMAJ440A.
5. The AC / DC conversion circuit for the blender drive motor according to claim 1, characterized in that, A bypass capacitor is connected between the OUTP and OUTN pins of the synchronous rectifier controller.
6. The AC / DC conversion circuit for the blender drive motor according to claim 3, characterized in that, The PWM controller includes a VFB pin, a VCC pin, an ISENSE pin, an OUT pin, and a GND pin; Both the ISENSE pin and the GND pin are connected to the negative common connection point; the VCC pin is connected to the positive common connection point through a third voltage divider resistor.
7. The AC / DC conversion circuit for the blender drive motor according to claim 7, characterized in that, The PWM controller is specifically a UC3842.
8. The AC / DC conversion circuit for the blender drive motor according to claim 1, characterized in that, The blender drive motor control sub-circuit includes a second voltage filter capacitor, a third voltage filter capacitor, a switching MOSFET, a freewheeling diode, an energy storage inductor, an output capacitor, a blender drive motor, a first sampling resistor, and a second sampling resistor; The second voltage filter capacitor, the third voltage filter capacitor, the freewheeling diode, the energy storage inductor, the output capacitor, and the blender drive motor are all connected in parallel between the negative common connection point and the positive common connection point; The switching MOSFET is connected in series between the third voltage filter capacitor and the freewheeling diode; the energy storage inductor is connected in series between the freewheeling diode and the output capacitor. The first sampling resistor and the second sampling resistor are connected in series and then connected in parallel across the two ends of the blender drive motor.
9. The AC / DC conversion circuit for the blender drive motor according to claim 8, characterized in that, The switching MOSFET is specifically an NCE65T180F field-effect transistor; The freewheeling diode is specifically a MUR1560.
10. The AC / DC conversion circuit for the blender drive motor according to claim 8, characterized in that, The gate of the switching MOSFET is connected to the OUT pin; the source of the switching MOSFET is connected to the third voltage filter capacitor; the drain of the switching MOSFET is connected to the cathode of the freewheeling diode. The VFB pin is connected between the first sampling resistor and the second sampling resistor.