Constant voltage, constant current and constant power output circuit based on motor inductance and MOS tube

Abstract

The utility model relates to motor control technical field discloses a kind of constant-voltage constant-current constant-power output circuit based on motor inductance and MOS tube, and circuit is composed of upper and lower bridge arms by six MOS tubes (VT1-VT6), and DC power Ud is input after voltage division filtering by capacitor C1, C2, and output end connects motor three-phase winding (L1, L2, L3) and resistance R1-R3.PWM control circuit controls MOS tube gate by 6-way IO, and upper and lower tubes on same bridge arm (such as VT1 and VT4) are not simultaneously conducted, to avoid short circuit.The utility model circuit is with motor inductance and MOS tube, and constant torque and constant-power output are realized by PWM control.Constant torque control maintains PWM duty ratio, guarantees rotating torque constant, and current is stable when load changes;Constant-power control is adjusted by closed loop PWM duty ratio, so that voltage and current product do not change, ensure output power constant, effectively improve the stability and adaptability of motor drive system.

Description

Technical Field

[0001] This utility model relates to the field of motor control technology, specifically to a constant voltage, constant current and constant power output circuit based on motor inductance and MOSFET. Background Technology

[0002] In traditional motor drive control, load changes can easily cause fluctuations in parameters such as speed and current, making it difficult to stably achieve constant torque or constant power output, thus affecting the stability and reliability of the drive system. Summary of the Invention

[0003] Based on this, the present invention provides a constant voltage, constant current and constant power output circuit based on motor inductance and MOSFET, in order to solve the problem that the existing motor drive circuit cannot stably achieve constant torque or constant power output when the load changes, resulting in poor motor operation performance and difficulty in meeting the application scenarios with strict requirements for output characteristics.

[0004] To achieve the above objectives, this utility model provides a constant voltage, constant current and constant power output circuit based on motor inductance and MOSFET, which includes a main circuit, a PWM control circuit and a closed-loop control unit. The main circuit includes a three-phase bridge arm, a motor, a DC power supply Ud, and voltage divider capacitors C1 and C2; the three-phase bridge arm consists of VT1 - The VT6 bridge consists of six MOSFETs. Each phase arm includes two MOSFETs, VT1 and VT4, VT3 and VT6, and VT5 and VT2, respectively. The two MOSFETs in the same phase arm do not conduct simultaneously. VT1, VT3, and VT5 share a common drain and are connected to the positive terminal of the DC power supply Ud, while VT2, VT4, and VT6 share a common source and are connected to the negative terminal of the DC power supply Ud. The voltage divider capacitors C1 and C2 are connected in series and then in parallel across the DC power supply Ud. The motor has motor inductors L1, L2, and L3 and resistors R1, R2, and R3. The connection point of VT1 and VT4 is connected to the neutral point N via resistor R1 and motor inductor L1, the connection point of VT3 and VT6 is connected to the neutral point N via resistor R2 and motor inductor L2, and the connection point of VT5 and VT2 is connected to the neutral point N via resistor R3 and motor inductor L3. The input of the PWM control circuit is connected to the MCU, and the output is connected to the gates of six MOSFETs VT1-VT6 through six IO interfaces to control the switching of the MOSFETs. The closed-loop control unit is used to synchronously acquire the voltage and current of the DC power supply Ud, and adjust the duty cycle of the PWM wave output by the PWM control circuit according to the acquired voltage and current signals to achieve constant voltage, constant current or constant power output.

[0005] Preferably, the closed-loop control unit includes a voltage acquisition module and a current acquisition module, which are used to acquire the output voltage and output current of the DC power supply Ud, respectively, and transmit the acquired signals to the MCU. The MCU adjusts the duty cycle of the PWM wave according to the deviation between the preset constant voltage, constant current or constant power target value and the acquired signal.

[0006] Preferably, the resistance values ​​of resistors R1-R3 are equal.

[0007] Preferably, the capacitance values ​​of the voltage divider capacitors C1 and C2 are equal.

[0008] The constant voltage, constant current, and constant power output circuit based on motor inductance and MOSFET of this utility model, by adopting the above technical solution, can achieve the following beneficial effects: This circuit utilizes the motor inductance and MOSFET to achieve constant torque and constant power output through PWM control. Constant torque control maintains the PWM duty cycle to ensure constant torque and stable current when the load changes. Constant power control adjusts the PWM duty cycle through a closed loop to keep the voltage-current product constant, ensuring constant output power and effectively improving the stability and adaptability of the motor drive system. Attached Figure Description

[0009] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0010] Figure 1 This is a circuit diagram of one embodiment of the constant voltage, constant current and constant power output circuit based on motor inductance and MOSFET of this utility model.

[0011] The purpose, features, and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Terms such as "upper," "lower," "left," "right," "middle," and "one" used in the preferred embodiments are merely for clarity of description and are not intended to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of the present invention.

[0013] like Figure 1 As shown, this utility model provides a constant voltage, constant current and constant power output circuit based on motor inductance and MOSFET, including a main circuit, a PWM control circuit and a closed-loop control unit (not shown in the figure). The main circuit includes a three-phase bridge arm, a motor, a DC power supply Ud, and voltage divider capacitors C1 and C2; the three-phase bridge arm consists of VT1 - The VT6 bridge consists of six MOSFETs. Each phase arm includes two MOSFETs, VT1 and VT4, VT3 and VT6, and VT5 and VT2, respectively. The two MOSFETs in the same phase arm do not conduct simultaneously. VT1, VT3, and VT5 share a common drain and are connected to the positive terminal of the DC power supply Ud, while VT2, VT4, and VT6 share a common source and are connected to the negative terminal of the DC power supply Ud. The voltage divider capacitors C1 and C2 are connected in series and then in parallel across the DC power supply Ud. The motor has motor inductors L1, L2, and L3 and resistors R1, R2, and R3. The connection point of VT1 and VT4 is connected to the neutral point N via resistor R1 and motor inductor L1, the connection point of VT3 and VT6 is connected to the neutral point N via resistor R2 and motor inductor L2, and the connection point of VT5 and VT2 is connected to the neutral point N via resistor R3 and motor inductor L3. The input of the PWM control circuit is connected to the MCU, and the output is connected to the gates of six MOSFETs VT1-VT6 through six IO interfaces to control the switching of the MOSFETs. The closed-loop control unit is used to synchronously acquire the voltage and current of the DC power supply Ud, and adjust the duty cycle of the PWM wave output by the PWM control circuit according to the acquired voltage and current signals to achieve constant voltage, constant current or constant power output.

[0014] Figure 1 The circuit shown consists of six MOSFETs (VT1-VT6) forming the upper and lower bridge arms. The DC power supply Ud is input after being divided and filtered by capacitors C1 and C2. The output is connected to the three-phase windings of the motor (L1, L2, L3) and resistors R1-R3. The PWM control circuit controls the gates of the MOSFETs through 6 I / O channels. The upper and lower MOSFETs of the same bridge arm (such as VT1 and VT4) are not turned on at the same time to avoid short circuits.

[0015] Constant torque control requires maintaining a constant motor torque. Based on load characteristics, speed and current change in opposite directions when the load changes, while torque is related to current. Closed-loop control maintains a stable PWM duty cycle, ensuring a constant current (and consequently, torque). When the load increases, speed decreases and current increases; the closed-loop system reduces the duty cycle to suppress current. When the load decreases, speed increases and current decreases; the system increases the duty cycle to boost current, thus maintaining constant torque.

[0016] Constant power control requires the power supply output power (voltage × current) to remain constant. When the load changes, the system adjusts the PWM duty cycle to change the combination of voltage and current. An increase in load leads to a decrease in speed, requiring a decrease in voltage and an increase in current, or vice versa, to keep their product constant. Conversely, a decrease in load leads to an increase in speed, requiring an increase in voltage and a decrease in current. Constant power is achieved through closed-loop adjustment of the duty cycle. The motor inductors L1-L3 act as energy storage and freewheeling during switching, working in conjunction with the high-frequency switching of the MOSFETs to smooth the output voltage and current, providing a stable basis for closed-loop control.

[0017] This circuit utilizes a three-phase bridge inverter topology, leveraging the motor inductor's energy storage for freewheeling and PWM closed-loop control to achieve constant torque and constant power output. Constant torque control is achieved by maintaining a stable current through the PWM duty cycle; constant power control is achieved by adjusting the duty cycle to keep the voltage-current product constant. Both are accomplished using the motor inductance and MOSFET switching characteristics, along with closed-loop feedback. Details are as follows: 1) Constant torque control Constant torque means maintaining a constant motor torque. This is achieved by maintaining the PWM duty cycle. The load characteristics are as follows: (1) When the load increases, the speed will decrease and the current will increase.

[0018] (2) When the load decreases, the speed will increase and the current will decrease.

[0019] 2) Constant power means keeping the power supply output power constant. The load characteristics are as follows: (1) When the load increases, the rotational speed will decrease, while (voltage * current) remains unchanged; (2) When the load decreases, the rotation speed will increase, while (voltage*current) remains unchanged.

[0020] Increase output power, decrease PWM duty cycle; decrease output power, increase PWM duty cycle.

[0021] Although specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A constant voltage, constant current, and constant power output circuit based on motor inductance and MOSFET, characterized in that, Includes the main circuit, PWM control circuit, and closed-loop control unit; The main circuit includes a three-phase bridge arm, a motor, a DC power supply Ud, and voltage divider capacitors C1 and C2; the three-phase bridge arm is composed of six MOSFETs VT1-VT6, and each phase bridge arm includes two MOSFETs, namely VT1 and VT4, VT3 and VT6, and VT5 and VT2, respectively. The two MOSFETs in the same phase bridge arm do not conduct simultaneously; VT1 - In VT6, VT1, VT3, and VT5 share a common drain and are connected to the positive terminal of the DC power supply Ud, while VT2, VT4, and VT6 share a common source and are connected to the negative terminal of the DC power supply Ud. The voltage-dividing capacitors C1 and C2 are connected in series and then in parallel across the DC power supply Ud. The motor has motor inductors L1, L2, and L3 and resistors R1, R2, and R3. The connection point between VT1 and VT4 is connected to the neutral point N sequentially through resistor R1 and motor inductor L1. The connection point between VT3 and VT6 is connected to the neutral point N sequentially through resistor R2 and motor inductor L2. The connection point between VT5 and VT2 is connected to the neutral point N sequentially through resistor R3 and motor inductor L3. The input of the PWM control circuit is connected to the MCU, and the output is connected to the gates of six MOSFETs VT1-VT6 through six IO interfaces to control the switching of the MOSFETs. The closed-loop control unit is used to synchronously acquire the voltage and current of the DC power supply Ud, and adjust the duty cycle of the PWM wave output by the PWM control circuit according to the acquired voltage and current signals to achieve constant voltage, constant current or constant power output. The resistance values ​​of resistors R1-R3 are equal, and the capacitance values ​​of voltage divider capacitors C1 and C2 are equal.

2. The constant-voltage, constant-current, constant-power output circuit based on motor inductance and MOS transistors according to claim 1, characterized in that, The closed-loop control unit includes a voltage acquisition module and a current acquisition module, which are used to acquire the output voltage and output current of the DC power supply Ud, respectively, and transmit the acquired signals to the MCU. The MCU adjusts the duty cycle of the PWM wave according to the deviation between the preset constant voltage, constant current or constant power target value and the acquired signal.

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