Engineers designing appliance pump and fan applications for large home appliances such as refrigerator, dishwasher, or washer and dryer need to consider a lot of factors when carefully constructing a motor drive system to meet their application requirements. In this product overview we consider a refrigerator fan motor system using a BLDC motor driver with efficiency as the key application requirement.

TI's BLDC motor driver designs solve these efficiency challenges with low voltage BLDC motor drivers with integrated sinusoidal and field-oriented control commutation methods for achieving peak performance out of a BLDC motor. Below we compare our efficiency performance against an existing industry design from Competitor A.

Test Considerations

In this refrigerator fan application, the main consideration here is the efficiency. We are measuring the power needed to be delivered to the motor to reach specific target RPMs. There are five target RPMs: 580, 910, 960, 1000, and 1080. Using the FG output given in Hz, we can convert to the target RPM given that this is a 12-pole motor (6 pole pairs) using the equation below:

For this benchmarking data, we used the Competitor A design as the baseline and determined the % efficiency difference while using DRV10974 as the TI BLDC design. The DRV10974 is an 18V abs max with integrated 180-degree sinusoidal commutation and integrated MOSFETs to allow for low power applications that require a small form factor. This driver has an H+L R_DS(on) of 750m$\Omega$ (typical) allowing for a phase drive current strength of about 1A Continuous (1.5A Peak). This device also includes a simple user interface with a slew of features including one-pin configurable start-up, a pin for forward and reverse control, an open-drain FG output for speed feedback, a resistor-configurable lead angle, current limit, and acceleration profile, and a full suite of protection features.

In this experiment we tested this design on three different refrigerator fan motors to provide data on a wider range of conditions.

Motor One

In motor one, we saw that system level efficiency can be improved by up to 7.6% varying across motor speeds while using DRV10974.

Motor Two

In motor two, we saw that system level efficiency can be improved by up to 8.2% varying across motor speeds while using DRV10974.

Motor Three

In motor three, we saw that system level efficiency can be improved by up to 8.4% varying across motor speeds while using DRV10974.

One of the key value propositions of DRV10974 is the ability to enter into a low-power mode when the motor is not spinning to conserve additional power as shown by the idle current in the table above.

As shown in the data above, TI’s DRV10974 outperforms competitor A at all target speeds across different motors offering engineers the best efficiency for their low voltage fan applications. Consider this when designing your next low voltage appliance fan system.