MotorXpert drives FOC motors without shunts or sensors

The latest MotorXpert motor control design software handles shuntless and sensorless technology for field-oriented control (FOC) for the first time.

The latest version of the MotorXpert tool from Power Integrations also simplifies the design flow for single-phase and three phase brushless DC motors (BLDC) inverters using the for the BridgeSwitch controller and adds support for advanced modulation schemes and unconditional startup under any load condition.

BridgeSwitch is a half-bridge motor driver of low RDS(on) FREDFET switches, controllers and drivers in a thermally efficient package. Sensorless feedback, fault reporting, and self and load protection are also available for applications from 30 W to 1 HP (750 W).

Applications include indoor and outdoor air conditioning fans, refrigerator compressors, fluid pumps, washing machine and dryer drums, range hoods, industrial fans and heat pumps.

“In this version 3.0 release, we have added a two-phase modulation scheme, which is ideal for applications that work in high temperature environments such as hot-water circulation pumps. The new modulation reduces inverter switching losses by 33 percent,” said Cristian Ionescu-Catrina, product marketing manager at Power Integrations.

“Version 3.0 also features a five-fold improvement to our waveform visualization tool and an enhanced zoom function, giving developers substantially more information for motor tuning and debugging. The intuitive interface follows the logic flow for motor tuning, and this shortens the learning curve. It also gives the motor condition and inverter configuration in one view with the motor speed and phase current to modify frequency and current parameters from the dashboard,” he tells eeNews Europe.

“We have upgraded the digital scope in the tool with four configurable independent channels and we have increased the resolution of the data by 3x to give more zoom capabilities,” he added. “This means you can see the dynamic and steady state response and it also gives the ability to scale and relative positions, for example to see the time lapse between signals.”

MotorXpert 3.0 uses algorithms resident on the local MCU or DSP construct accurate feedback signals from the BridgeSwitch and provide real-time control of the switching patterns. A host-side application interprets inverter actions and displays critical data in actionable format for engineering analysis. The control interface permits development engineers to experiment and quickly converge to a final product.

The software is MCU-agnostic and precompiled for an entry level Cortex M0+ so it is upwards compatible for many controllers. It also includes a comprehensive porting guide to simplify deployment with a wide range of MCUs. It is implemented in common C language to MISRA standards.

“The tool is MCU agnostic. It is written in C and can be ported to any microcontroller,” said Ionescu-Catrina. “There are so many different microcontrollers out there so we are offering this ability to port the code in no time. The GUI is also MCU agnostic.”

“For non-ARM microcontrollers we are providing a porting guide with description of the APIs so customers can transition and we have examples moving from ARM to a proprietary core in four days,” he said. PI plans to extend the supported library moving forward to allow the download the same code regardless of the microcontroller type.

The MotorXpert v3.0 host application includes a graphical user interface to configure parameters and operation and simplifies debugging. Parameter tool tips and a tuning assistant improve the development process, and the intuitive parameter list provides easy motor tuning.

The update also features both V/F and I/F control, which permits motor startup in any load condition. A selectable two-phase modulation scheme allows developers to trade off temperature of the inverter vs torque ripple which is beneficial in applications such as hot water circulation pumps, reducing heatsinking requirements and enclosure cost. Development time is greatly reduced by the included single- and three-phase code libraries with sensorless support, reference designs, and other tools such as a power supply design and analysis tool.

“We made the flow more logical to really match now the motor should be driven, but it also offers two configuration modes, an easy one for vector estimation with two parameters. For the Xpert mode with five parameters to define the rotor position for people who know more about the how the motor works. This is new,” he said.

“The motor control works in a system so it needs to take account of the feedback. In the past this was only possible through modifying the code. Now what we have done is the software recognises faults and provides solution support so the user can select in the protection tab how the system reacts when different faults happen, it’s just a matter of configuration for the six of seven faults.”

MotorXpert v3.0 is available at no cost with an end-user license agreement. The FOC motor control software suite comes with a quick start guide, software manual, MCU porting guide, single- and three-phase software libraries.