Many applications use BLDC or Brushless DC motors for powering several types of high-speed equipment. These include industrial machines, data center cooling fans for servers and home vacuum cleaners. One of the challenges designers face is to ensure the motors operate effectively and reliably. Now, Toshiba is making it easy for designers to do this with its intelligent phase control motor controller.
While other manufacturers also offer intelligent phase control devices, they usually meet a specific design need. Toshiba’s TC78B016FTG has a driver rated for 40 VDC and 3 A maximum. The fully integrated motor control driver requires a power supply ranging from 6 to 36 VDC, and provides a sine wave output drive. ON resistance of the driver is only 0.24 ohms, representing the total of low and high sides. This typically reduces the self-heating of the device during operation and allows driving 1 to 1.5 A loads without a heat sink.
TC78B016FTG uses a simple speed control mechanism using pulse width modulation. It has several built-in protections, and these include protection from over-current, thermal runaway, and motor lock. Toshiba offers the TC78B016FTG in a 5 x 5 mm VQFN32 package.
Other controllers from Toshiba include the TC78B941FNG and TC78B042FTG. These intelligent phase controllers allow users to tailor the power requirement of an application by selecting a proper MOSFET and its gate driver for the design. Toshiba offers these devices in SSOP30 and VQFN32 packages respectively. Both measure 5 x 5 mm.
Another controller from Toshiba is the TC78B027FTG, which incorporates a gate driver, for which the user can select the proper MOSFETs according to the application. This controller also has a one-Hall drive system for the user to drive a less expensive one-sensor BLDC motor. Toshiba offers the device in a VQFN24 device measuring 4 x 4 mm.
Conventional drive technology adjusts the phase or lead angle of the voltage and current it feeds to the motor for achieving high-level efficiency. However, high-speed rotation prevents the magnetic drive from reaching maximum power, as phase lag delays the voltage applied to the coil from rising until the current has increased to a maximum.
Intelligent phase controllers avoid the above situation by advancing the rotor by a certain angle from the calculated position. This is the new lead angle that depends on the BLDC motor’s characteristics, its rotational speed, and load conditions.
Designers try to achieve optimal efficiency over rotational speeds ranging from almost zero rpm at motor startup to several thousand rpm at high speeds. As this requires several characterizations for adjusting the phase, they achieve optimal efficiency only for a limited range of speeds. Intelligent phase controllers allow BLDC motors to rotate at high speeds with uniform accuracy and efficiency.
Compared to earlier technologies, the approach taken by Toshiba is different. Rather than adjust the phase difference between the voltage and current to the motor at different points in its operating range, Toshiba automatically and continually adjusts the phases of voltage and current the controller feeds to the motor. Intelligent phase controllers from Toshiba thereby achieve the highest possible efficiency for the entire operating range of the motor.
