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Soft-start switching control circuit and control method for brushless DC motor

A brushed DC motor and control circuit technology, applied in the direction of the starting device, etc., can solve the problems of severe vibration of the motor operation, change of the PWM duty cycle of the chip output, and non-smooth start.

Active Publication Date: 2018-10-09
FORTIOR TECH SHENZHEN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But because the external is an analog speed regulation, when the internal PWM ends, I don’t know the value of the external setting. The internal PWM and the external speed setting may not correspond. If the internal PWM works after the end of the time, the internal PWM cannot correspond to the external adjustment. The value corresponding to the speed, the chip output PWM duty cycle will change suddenly, which will cause the motor to vibrate violently, which is manifested as an unsmooth start.

Method used

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  • Soft-start switching control circuit and control method for brushless DC motor
  • Soft-start switching control circuit and control method for brushless DC motor
  • Soft-start switching control circuit and control method for brushless DC motor

Examples

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Embodiment 1

[0021] Such as figure 1 As shown, the present invention provides a soft-start switching control circuit for DC motor drive control, including a switching circuit and an external control circuit. Wherein, the switching circuit includes a voltage follower U1, a voltage follower U2, an inverter U3, a PMOS transistor MP1, an NMOS transistor MN1, a filter resistor R1 and a switch transistor U5. The input terminal of the voltage follower U1 is connected to the voltage V1, and the output terminal of the voltage follower U1 is connected to the source of the PMOS transistor MP1. The input terminal of the voltage follower U2 is connected to the voltage V2, and the output terminal of the voltage follower U2 is connected to the source of the NMOS transistor MN1. The input terminal of the inverter U3 is used for inputting the PWM signal for controlling the starting of the motor, and the output terminal of the inverter U3 is connected to the gates of the PMOS transistor MP1 and the NMOS tr...

Embodiment 2

[0040] The circuit of this embodiment is basically the same as that of Embodiment 1, and the only difference is that the circuit of this embodiment does not include the filter resistor R1. Such as image 3 As shown, one end of the switch tube U5 is connected to the drain of the PMOS tube MP1 and the drain of the NMOS tube MN1, and the other end of the switch tube U5 is connected to one end of the resistor R2, the resistor R3, and the capacitor C1 as a soft-start switching circuit. The output terminal is connected to the non-inverting input terminal of the comparator U4, the inverting input terminal of the comparator U4 is connected to a sawtooth wave signal whose amplitude is between the voltage V1 and the voltage V2, and the output terminal of the comparator U4 is connected to the motor for controlling The speed of the motor. The other end of the resistor R2 is connected to the power supply VDD, the other end of the resistor R3 and the other end of the capacitor C1 are groun...

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PUM

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Abstract

The invention provides a soft start switching control circuit and control method for a brushless direct current motor. The soft start switching control circuit comprises a switching circuit and an external control circuit. The switching circuit comprises a voltage follower U1, a voltage follower U2, a phase inverter U3, a PMOS transistor MP1 and an NMOS transistor MN1. The output end of the voltage follower U1 is connected with the source of the PMOS transistor MP1. The output end of the voltage follower U2 is connected with the source of the NMOS transistor MN1. The output end of the phase inverter U3 is connected with the gates of the PMOS transistor MP1 and the NMOS transistor MN1. The source of the PMOS transistor MP1, the drain of the NMOS transistor MN1 and the output end of the external control circuit are connected as the output end of the soft start switching control circuit and the output end is used for controlling a rotating speed of a motor. According to the circuit and the method, the switching circuit is arranged, so a rotating speed value controlled by the external control circuit corresponds to the rotating speed value controlled by internal PWM, and the operation of the motor is transited smoothly.

Description

technical field [0001] The invention relates to the technical field of soft start for drive control of brushless direct current motors, in particular to a soft start switching control circuit and control method for brushless direct current motors. Background technique [0002] At present, in the brushless DC motor drive control chip, external analog speed regulation is often used. Not only can the speed regulation through resistor voltage division not need to increase the MCU, but also can directly adjust the speed manually through the adjustable resistor, which reduces the cost and is convenient to use. The basic speed regulation method of the driver chip. However, when the motor is started, especially when the sensorless brushless DC motor is started, a starting PWM is first set internally. After the motor starts, the chip can clearly detect the back EMF of the winding, and then the speed of the motor is adjusted by the external simulation. The value and the speed corres...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02P6/20
CPCH02P6/20
Inventor 陈思军毕超毕磊
Owner FORTIOR TECH SHENZHEN