High Voltage Brushless DC Motor Control
Schematic Block Diagram for High Voltage Motor Controllers
Motor Control: High Voltage Overview
HVAC motors, Industrial Inverters, or HV Permanent Magnet Brushless motors are examples of high-voltage systems and typically classified by their power in horsepower. Although rotary motors are the most common, other configurations are available, such as linear motors, and gear head motors with various implementations of actuators built on.
Digital motor control solutions precisely control the position, velocity, and torque of these mechanical drives. MOSFETs in such large drives typically exceed 600V. TI has gate drive solutions TPS2829, for example; a non-inverting high-speed MOSFET Driver. When combined with the TLV3501 comparator in the feedback loop, the gates in these systems can be digitally controlled. Alternatively, TI MOSFET drivers such as UCC37321 or UCC37323 can drive smaller motors directly or drive power devices such as MOSFETs or IGBTs.
The Core Subsystems Include:
Controllers
TI offers a range of solutions for the control processor; from the ultra-low power MSP430 microcontroller to the ARM® Cortex™-R4F-based Hercules™ Safety MCUs and C2000 Digital Signal Controllers (DSC). The right controller can optimize motor drive efficiency, improve reliability and lower overall system costs.
The 32-bit DSP-class performance and motor-control optimized on-chip peripherals of the C2000 controllers enable users to easily implement advanced algorithms such as sensor-less vector control of three-phase motors. The C2000 family offers software-compatible controllers ranging from the low-cost F28016 to the industry’s first floating-point DSC, the TMS320F28335.
Isolation
TI Digital isolators have logic input and output buffers separated by TI’s silicon dioxide (SiO2) isolation barrier, providing 4kV of isolation. Used in conjunction with isolated power supplies, these devices block high voltage, isolate grounds, and prevent noise currents from entering the local ground and interfering with or damaging sensitive circuitry.
Controller Interface
RS-232 or RS-422 are adequate for many systems. RS-485 signaling may be bundled with protocols such as Profibus, Interbus, Modbus or BACnet, each tailored for the specific requirements of the end user. Sometimes controller area network (CAN) or EtherNet/IP (Industrial Protocol) are preferred do to network requirements. M-LVDS can provide lower power dissipation alternative. See the app note for additional information on interface selection.
Motion Feedback Using External Circuits
Isolated delta-sigma modulators (AMC1203/AMC1210) are ideal for shunt measurements to flatten glitches and increase current feedback resolution. Alternatively, INA19x (x=3 to 8) and INA20x (x=1 to 9) provide wide common-mode voltages for both low-side and high-side current shunt monitoring. Hall Effect or magnetic based sensors are typically more efficient when measuring over 10 Amps; plus they inherently provide isolation. ADS1204, ADS1205 and ADS1208 are recommended for this. To connect ±10V (20Vpp) signals to an analog-to-digital converter (ADC) using only a 3.3V or 5V supply, use an INA159 level translation difference amplifier. ADCs like ADS7861/ADS7864 or ADS8361/ADS8364 provide 4-channel or 6-channel simultaneous current sampling.
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