Voltage Follower Opamp Current Amplification/Inrush/Power Consumption

[electrovanga]

Hello,
I got an idea that when I have a 6V, 1.5A(Max. Contionious) battery with an voltage follower opamp, I cantprovide more current and more outpu voltage with lower impedance in theory that I know. My question is do you think  it is possible. I drive a dc brushed motor and i would like to compansate inrush current and the high voltage drop issue on the battery.

I attach one example circuit. The question here is if i set the zener to 5.2V as referance voltage. How will the current supply amplified, battery will consume less current or the inrush current will be limited? I think I need a transistor to limit the inrush current.

[mtwieg]

That circuit basically behaves as a linear regulator, reducing the 6V battery voltage to 5.2V. This will reduce inrush current, but not by much, and power efficiency will be bad.

Normally one drives a brushed DC motor with high frequency PWM, which is very power efficient. By changing the PWM duty cycle you can soft-start the motor to reduce inrush.

[electrovanga]

My idea was after this circuit connect the half bridge to the output of opamp and apply PWM. I was imagining kind of double inrush current protection. Because, I can not really get what I want with soft start and PWM adjustment.

[mtwieg]

My idea was after this circuit connect the half bridge to the output of opamp and apply PWM. I was imagining kind of double inrush current protection. Because, I can not really get what I want with soft start and PWM adjustment.

I don't think there's any protection this circuit provides that proper pwm control can't replicate (though the pwm control might be a bit complicated). Maybe you can describe the inrush issue in more detail? Does it happen when changing speed quickly, or when the load on the motor is increased suddenly? What is generating the PWM for the half bridge?

[Circlotron]

Maybe replace the zener diode with a capacitor that will charge up slowly, and by doing so will soft start the motor. And preferably put a diode across the resistor that feeds this capacitor to make the capacitor discharge when the power is removed.