Motor Control H-Bridge: PWM Input to Get Red Output Signal

In summary, the conversation discusses building an H-bridge to control a motor in both forward and reverse modes. The speaker has drawn a schematic and is having trouble with the output signal, which they need to look like a specific red signal. They mention input signals and a logic table, but it is not clear what the exact problem is. The conversation ends with a suggestion to use a negative voltage supply and an op-amp to add the two signals.
  • #1
anita1984
34
0
I am building a H-bridge to control motor in forward mode and reverse mode , in the attachment i draw the schematic of the circuit , my problem is that the output signal looks like in the picture DSC07167 black signal and i need it like the red signal. How should the input signal of 2 PWM to have on the ouput the both mode? What do you recomand me. my inputs(before logic gates signals) are in the picture DSC07168
Thanks in advance,
 

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  • #2
anita1984 said:
I am building a H-bridge to control motor in forward mode and reverse mode , in the attachment i draw the schematic of the circuit , my problem is that the output signal looks like in the picture DSC07167 black signal and i need it like the red signal. How should the input signal of 2 PWM to have on the ouput the both mode? What do you recomand me. my inputs(before logic gates signals) are in the picture DSC07168
Thanks in advance,

Sorry, I'm not quite understanding the question. Your circuit looks okay for driving the H-bridge, assuming the logic drive signals are correct. Perhaps you could show us your truth table for the 4 logic inputs to the drive circuit?
 
  • #3
Hello i am sending the logic table , i think i have problem with the input signals to the logic gates and the result isn't like my need
A and B are in input to the logic gates
Av and Bv are the output from thr logic gates

A B Av Bv
1 1 0 0
1 0 1 0
0 1 0 1
0 0 0 0


Thanks in advance
 
  • #4
I'm assuming that the red signal has a negative voltage component. In that case your first going to need a negative voltage supply and your probably going to want to add the two signals using an op-amp, also commonly called an "adder".

AdderAmp.gif
 
  • #5
anita1984 said:
Hello i am sending the logic table , i think i have problem with the input signals to the logic gates and the result isn't like my need
A and B are in input to the logic gates
Av and Bv are the output from thr logic gates

A B Av Bv
1 1 0 0
1 0 1 0
0 1 0 1
0 0 0 0


Thanks in advance

What are A, B, Av, Bv? I don't see them labelled in the schematic. And what is the output for each of those input combinations?
 

Q1: What is a motor control H-bridge?

A motor control H-bridge is a circuit that allows for the direction and speed control of a DC motor. It consists of four transistors arranged in an "H" shape, with the motor connected between the middle of the "H" and the power supply.

Q2: What is the purpose of using PWM input in motor control H-bridge?

PWM (Pulse Width Modulation) input is used in motor control H-bridge to control the speed of the motor. By varying the duty cycle of the PWM signal, the average voltage applied to the motor can be adjusted, thereby controlling its speed.

Q3: How does the H-bridge control the direction of the motor?

The H-bridge controls the direction of the motor by switching the transistors on and off in a specific pattern. By turning on and off the appropriate transistors, the current can be directed through the motor in either direction.

Q4: What is the role of the red output signal in motor control H-bridge?

The red output signal is the result of the PWM input being processed by the H-bridge circuit. It is the signal that is sent to the motor, controlling its speed and direction.

Q5: What are the applications of motor control H-bridge?

Motor control H-bridges are commonly used in robotics, electric vehicles, and other applications where precise speed and direction control of a DC motor is required. They are also used in household appliances such as fans, washing machines, and electric drills.

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