An isolated h-bridge driving device

Abstract

The invention discloses an isolated H-bridge drive device, which realizes the drive of the H-bridge by combining an isolation transformer and optocoupler isolation, the optocoupler is used to isolate the drive signal of the upper bridge arm of the H-bridge, and the isolation transformer generates The voltage is used to provide the working voltage for the isolated driving signal circuit. At the same time, the negative pole of the voltage generated by the isolation transformer is connected to the common terminal HV‑360V‑ of the lower bridge of the H bridge arm, and is isolated from the ground of the driving signal chip, which can make the driving The signal directly drives the power MOSFET tubes of the upper and lower bridge arms in the H-bridge circuit, and the driver chip does not need to add a circuit to increase the driving voltage, which makes the application range of the driver chip more extensive, and the saved space can be used to increase other performance and electrical characteristics. Compared with the high-cost special-purpose driving chip, the present invention has the advantages of low cost, safety and reliability, and the driving device does not need boosting by a bootstrap capacitor, and can produce the same function and electrical characteristics as the special-purpose IC.

Description

technical field [0001] The present invention relates to the field of power supplies, and more specifically, to an isolated H-bridge driving device. Background technique [0002] In the H-bridge circuit, the H-bridge is mostly used for commutation to transfer energy. The four tubes of the current H-bridge circuit generally use the same type. The two pipes of the lower bridge can share the ground, but the two pipes of the upper bridge cannot share the ground. The H-bridge circuit is mostly connected to a high-voltage circuit. Since the two tubes of the upper bridge cannot be connected to the ground, they are in a floating connection state, so the driving signal voltage needs to be raised or isolated from the ground. Especially, for DSP or FPGA as When driving the source, because the driving circuit is often grounded without raising the driving voltage, it cannot be directly used to drive the upper bridge arm of the H-bridge with the ground signal. Existing methods for increa...

AI Technical Summary

Problems solved by technology

The two pipes of the lower bridge can share the ground, but the two pipes of the upper bridge cannot share the ground

The H-bridge circuit is mostly connected to a high-voltage circuit. Since the two tubes of the upper bridge cannot be connected to the ground, they are in a floating connection state, so the driving signal voltage needs to be raised or isolated from the ground. Especially, for DSP or FPGA as When driving the source, because the driving circuit is often grounded without raising the driving voltage, it cannot use the ground signal to directly drive the upper bridge arm of the H bridge.

Existing methods for increasing the driving voltage include the method of boosting the capacitor, and the method of using a BOOST circuit to boost the voltage. A dedicated chip can also be used to increase the driving voltage, and there is also a method of directly isolating the drive by using an isolation transformer. These methods Unfavorable factors will complicate the design of the drive circuit, increase the difficulty of the design, and are not conducive to mastering the results of the control design, resulting in lower reliability of the designed product and bringing more design costs.

Images