Current-limiting protection device and motor driving chip

Abstract

A current-limiting protection device comprises a current sampling circuit which is connected with a driving power device and is used for sampling the current of a load and converting a sampling current signal into a sampling output voltage signal, and a PWM signal transmission and control circuit which is in signal connection with the current sampling circuit and the PWM and is used for controlling the driving power device to be turned on or turned off according to a comparison result of the sampling output voltage and a reference voltage. According to the scheme of the invention, the current-limiting protection device is integrated in the motor driving chip, peripheral elements such as an armature series resistor and a switching tube for starting the motor are omitted, and the developmentcost and the motor driving loss are reduced. Moreover, the starting current is controlled by sampling the current of the power tube cycle by cycle, the current-limiting starting function of the motorcan be realized without changing the duty ratio of the preset PWM signal, and the current-limiting function of the device is automatically stopped after the motor is started, so that the normal transmission of the preset PWM control signal is not influenced.

Description

technical field [0001] The invention relates to the technical field of motors, in particular to a current limiting protection device and a motor drive chip. Background technique [0002] In the motor drive, such as the starting stage of a DC motor, since the motor speed is 0, the corresponding electromotive force e of the armature of the motor is also 0. If the applied voltage is the rated voltage Vin, considering that the armature resistance Ra is small, the voltage balance equation It can be seen that the starting current will be relatively large, generally speaking, the starting current can reach 10 to 20 times the rated current. Such a high start-up current may cause overheating of the driving power switch tube, thereby damaging the power switch tube, and such a large current impact may cause an instantaneous drop in the power supply voltage, thereby affecting the normal operation of other circuits around the power grid. Therefore, the usual solution is to use a curre...

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Problems solved by technology

[0004] However, the disadvantages of the above-mentioned prior art are: 1. In the armature circuit series resistance starting scheme, the circuit needs external components such as resistors and switches, which increases the cost of circuit design. At the same time, increasing the resistance element will inevitably increase the loss on the resistance

2. Relying on changing the PWM duty cycle of the drive signal to reduce the voltage. In the starting scheme, it is necessary to design a PWM signal with a complex duty cycle, and it is necessary to judge when the start-up ends, which increases the difficulty of designing the overall circuit.

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