What Is an H-Bridge?

The H-bridge is a typical DC motor control circuit, because its circuit shape is exactly like the letter H, so it is named "H-bridge". The four triodes make up the four vertical legs of H, and the motor is the horizontal bar in H (note: the figure is only a schematic diagram, not a complete circuit diagram, and the driving circuit of the triode is not shown).

H bridge is a

H-Bridge (H-Bridge), because of its similar appearance to H, is often used for

The control of H bridge is mainly divided into approximate square wave control and

H-bridge control is mainly divided into approximate square wave control, pulse width modulation (PWM) and cascaded multilevel control. The approximate square wave control is quasi-square-wave-control. The output waveform has a 3-level more than the positive and negative alternating square waves, and the harmonics are greatly reduced. The advantage is that the switching frequency is low, the disadvantage is that the harmonic component is high, and the cost of the filter is large.

H-bridge pulse width modulation

Pulse width modulation, which is divided into unipolar and bipolar pwm. With the increase of the switching frequency, the output voltage and current waveforms tend to be sinusoidal and the harmonic components are reduced, but high switching frequency brings a series of problems: switching loss Large, motor insulation pressure is large, heat and so on.

H-bridge cascade multilevel control

That is, the multi-level inverter adopts the cascaded H-bridge method, which reduces the harmonic distortion to the minimum at the same switching frequency, and does not even need a filter to obtain a good approximate sinusoidal output waveform. ^[2]