EW - Hardware-Software solution for three-phase BLDC motor inverters

Power Integrations has unveiled new control software for three-phase BLDC motor drives.

Combined with the company’s BridgeSwitch integrated half-bridge motor driver and easy-to-use Motor- Expert configuration and diagnostics tool, this complete hardware-software solution delivers 98.2 percent efficiency, reduces board space by more than 70 percent and requires just three components for current feedback circuitry, compared to 30 components in a discrete solution.

The solution is intended for residential and commercial appliances with three-phase motors, such as air conditioner fans, high-speed hair dryers, refrigerator compressors, range hood fans and water pumps.

Power Integrations’ new software adds three-phase FOC to the existing library of single-phase code and allows real-time adjustment of motor speed and torque via the Motor-Expert graphical user interface (GUI). The code runs on any Arm Cortex-M0 at 48 MHz and does not require a hardware accelerator block. It can also be ported to other equivalent MCUs.

The current modelling algorithm is robust and reliable and has passed extensive static and dynamic test conditions, including low latency response to real-time events. The high degree of current accuracy ensures low jitter operation. The new code is MISRA C-compliant (Motor Industry Software Reliability Association), portable, modular and allows the user to modify any of the software layers.

Power Integrations’ BridgeSwitch ICs provide a motor current output signal that maps the current passing through the low-side FREDFET - an internal sense-FET provides lossless current sensing. The sense circuit cannot provide current information when the anti-parallel body diode is conducting during commutation. Built-in gain amplification allows direct connection of the current phase signal to the microcontroller ADC input. The local sense circuit provides an accurate analogue of current with a high signal-to-noise ratio and a correspondingly high degree of accuracy.

The new software includes a reconstruction algorithm that uses the phase-shifted trigonometric relationship between current signals of all three phases to accurately deduce negative phase-current information.

Motor-Expert 2.0 is Power Integrations’ motor control configuration and diagnostics tool for the BridgeSwitch IC family. It supports easy manipulation of input parameters, as well as a terminal emulator for interacting with the motor controller in serial mode. In addition, a motion scope feature displays linear graphs of important controller variables that can be viewed in real time.

Motor and application tuning is performed through the Motor-Expert 2.0 GUI with control loop coefficients being updated in real-time without having to recompile code. The interface also enables users to visualise system operation, displaying the status of data, including current, speed, status, current error, and speed error. A diagnostics field within the software interface provides insight into inverter and motor operation.

Motor-Expert 2.0 supports three-phase and single-phase motor drive design and replaces the previous version of Motor-Expert.