Gate driver chip for DC motor control

[XaviPacheco]

Hello,

I'm looking for a proper gate driver for driving a power DC motor (4HP). I do not want to control direction. I attach one that I found while searching in Texas Instruments products, UCC27712. However. I'm confused about that chip when it says High-Side Low-Side. What does that mean by high and low side? How could I use that chip to control DC motor speed in one direction?

[james_s]

High side, low side is a dual mosfet controller intended for driving a half bridge as shown in that picture. If all you want to do is control a DC motor then what you want is a single low side mosfet driver. One that I recently used for just such a task is IXDI609PI.

[Siwastaja]

The one shown, dual MOSFET-based half-bridge, has the added benefit of running at higher efficiency (especially relevant in low voltage systems, or systems running at low rpms, high torques) compared to the single mosfet + diode solution; this is because diode has higher voltage drop than a mosfet. Another added benefit is that the dual mosfet half-bridge can do regenerative braking with permanent magnet DC motors. (This can be a downside as well - you need to monitor the input DC voltage, detect overvoltage situation and bring the gate driver enable signal low to make the motor freewheel. This overvoltage situation can happen especially if you have a flywheel-like mechanical load that stores a lot of inertia.)

High-side+low-side (as imaged) is often the way to go because integrated bootstrap gatedrivers, as shown, are commonplace and cheap. While single mosfet + diode solution is theoretically simpler (needing simpler low-side only gate driver), there is not that much actual price difference. Also, the increased power dissipation in the diode may increase heat sinking costs.

For the diode version, if you want to go that way, just replace the upper mosfet with a diode (doesn't need a gate driver ), and the gate driver with a low-side gate driver IC.

To make a decent motor driver, especially with bigger motors, you definitely need current sense, though (not shown). For small motors with high winding resistance, just oversizing the FETs (or 1 FET + diode) to handle the stall current (expect 10 times the nameplate current if no other info available) is often enough.

For a 4HP motor, I'd definitely do some more homework first. You need to learn about:
- current sense
- DC link bypassing, and
- layout considerations
- control schemes, which can be trivial, but nevertheless you need to have an idea how to control the PWM duty based on current and voltage measurements.