Software eases BLDC motor driver design -

Software eases BLDC motor driver design

During PCIM, Power Integrations presented an embedded “C” code application, library and control GUI that enables designers using the company’s BridgeSwitch brushless DC (BLDC) motor driver ICs to precisely control and tune single-phase motors. In an interview with Power Electronics News, Cristian Ionescu-Catrina, Sr. Marketing Manager, Power Integrations, highlighted how a new eco-design for each motor driver is making its way into the consumer sector. “New regulations increase efficiency challenges: dishwashers are required to be 30% more efficient and the EU targets $20B in energy savings by 2035,” said Ionescu-Catrina. This leads us to simplify fault diagnosis and design with new solutions to meet market demands with lower audible noise and accurate control, supported by BLDC motors as a cost-optimised solution in single-phase applications. BLDC motors are widely used in modern, high-efficiency appliances such as compressors, fans and water pumps in domestic appliances, and for ceiling fans and room air conditioning systems.

BridgeSwitch BLDC motor drive ICs support emerging market requirements with an integrated, flexible half-bridge that drives up to 400 W without heatsinks. BridgeSwitch drives single-phase or three-phase motors with hardwired protection and monitoring of the entire inverter. Ionescu-Catrina pointed out that the design of motor control applications requires complex solutions, and simplifying the process in hardware and software is a requirement for all designers. Currently, software examples work with a specific motor and don’t have a built-in mechanism for customization. Moreover, traditional inverter solutions lack diagnostics, relying on software to pass Safety Class B per IEC-60730, taking two to three months longer to certify than a hardware solution.

“Customers require total solutions with software examples and design tools,” said Ionescu-Catrina. “Motor control applications need customization [and to] have an optimum operating zone; proportional integral loops need configuration; PWM frequency and thermal specs vary; fast and smooth start-up is required.

“For example, in Figure 1, on the x-axis, you have the airflow; on the y-axis, you have the air pressure, and there is an optimal operating zone for each type of fan,” he detailed. “So to get the fan to that operating mode, customization and tuning are necessary. So the motors have to be optimized; they have to be tuned to operate in that optimal operating zone, which requires significant effort by the designer. Designers must also consider other use cases, such as speed control concerning proportional-integral control constants. And this also needs configuration such as Kp parameters. In addition, many designers also want to optimize the MCU from a memory and bandwidth perspective to minimize PCB space and heating. All this is possible with the new software that Power integrations is presenting at PCIM this year.”

Figure 1: Motor control applications need customization. (Source: Power Integrations)

BLDC motors

BLDC motors offer greater efficiency and reliability than brushed motors. They are increasingly being used in household appliances and consumer electronics. As efficiency standards for these applications continue to tighten, better power-conversion technology is also needed to minimize total power losses and simplify the design. The driver is a basic element of BLDC control. It is a power amplifier that produces a voltage output to drive the high-current high-side and low-side IGBT gates of the H-bridge circuit.

To meet future demands, at PCIM, Power Integrations presented a new GUI for single-phase motor system design using the BridgeSwitch family for BLDC motors up to 400 W. This high-voltage half-bridge motor is 99.2% efficient, requires no heatsink, and reduces software certification time and expense. The BridgeSwitch driver family from Power Integrations features advanced fast-recovery epitaxial-diode field-effect transistors (FREDFETs) with integrated lossless current sensing.

Through the interface, it is now possible to control the start and stop of the motor, as well as the protection parameters, making it possible to monitor the status of the motor without any external instrumentation. Figure 2 shows the list of possible states that the interface allows you to program and its layout. The BridgeSwitch Motor-Expert software reduces the cost and complexity of BLDC drives.

click for full size image

Figure 2: Features and layout of new GUI (Source: Power Integrations)

Figure 3: Example of system architecture — sensor control (Source: Power Integrations)

“The interface allows you to make all changes in several configurations in real time,” said Ionescu-Catrina. “Every time you make a change, the configuration will be updated in the microcontroller and its software. There is no need for recompilation and everything happens in real time.”

The interface also enables users to visualize 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.

The new software comes with ready-to-use application examples for constant-speed and constant-torque operation, all of which are IEC6730 Class A-ready. The GUI can be downloaded together with examples and documentation. An MCU is, of course, still required for the control system (Figure 3).

The software meets static (MISRA) and dynamic performance profiling covering latency, jitter and execution time.  It requires only 14 kB code memory and 5 kB SRAM, suiting it to microcontrollers with small memory capabilities.

>> This article was originally published on our sister site, Power Electronics News.

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