Next, a specific driving method of a brush DC motor uses an H-bridge circuit PWM drive will be described.
Drive a brush DC motor using the PWM output mode
H-bridge circuit PWM driver
This article describes two typical examples of the PWM drive when a brush DC motor is powered by the H-bridge circuit.
1 Enter the PWM signal to one of the two input pins and drive directly
When "drives a brush-driven DC motor by H-bridge circuit: the switching of the H-bridge circuit drives the motor, two logical inputs can be used in 4 states (stop, forward, reverse, braking) Switching between. The first PWM drive method is to input the PWM signal to one of the two input pins.
This is a block diagram of a brush DC motor driver IC. Use IN1 and IN2 logic to switch H bridges. The left side of the two truth tables is the standard switching logic. Among them, H input of forward (H / L) and reverse (L / H) is used as PWM input. See the truth table on the right. This is the opening (Open), forward PWM driver, reverse PWM driver and brake. In this control, the logic signal and the PWM signal need to be sent from the microcontroller or the like to IN1 / IN2. Of course, the driver IC needs to support this driving method.
In this method, the duty cycle of the PWM input signal is equivalent to an equivalent average amount of the duty ratio of the power supply voltage Vm.
2 Motor driver with VREF PWM control
Some motor driver ICs are ICs equipped with a PWM function. In this example, the driver IC is a triangular wave generator and a comparator inside, and can perform the type of output PWM driver and PWM duty cycle.
It can be understood by block diagrams and waveform graphs. The comparator outputs the result of the triangular wave of triangular wave generators and the external reference voltage Vref. The output duty cycle of the comparator is determined by VREF. When VREF is a minimum amplitude value of 0V of the triangular wave, the duty cycle is 0%; when VREF is the maximum amplitude VPH of the triangular wave, the duty cycle is 100%. The output (PWM signal) of the comparator is combined with the IN1 / IN2 logic, and output to OUT1 / OUT2 via the H-bridge.
As in principle, just as described, 1 and 2 can be powered by the H-bridge, but due to the built-in to prevent simultaneous conductive circuits, and 2 analog circuit is used to generate a PWM signal, it may be required Adjustments other than some theories (such as linearity and errors).
Key points:
● There are several types that support the PWM-driven H-bridge bridge-brush DC motor driver IC.
- You can directly input the PWM signal to the type of IN1 / IN2.
- A type of PWM signal generating circuit equipped with a VREF pin, a triangular wave generator, and a comparator.
Original title: R Class | Using PWM Output Mode Drive DC Motor: H-bridge circuit PWM driver
Article Source: [WeChat public number: Roma Semiconductor Group] Welcome to add attention! Please indicate the source of the article.
Editor: Haq, Read full article, original title: R Class | Using PWM output mode Drive Bridge DC Motor: H-bridge circuit PWM driver
Article Source: [Micro Signal: Roma Semiconductor Group, WeChat public number: KYOCERA Jing Porcelain China Business] Welcome to add attention! Please indicate the source of the article.
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