High-integration chipset for small electric motors in traction applications
AEC-qualified integrated solutions for electric traction
Electric traction for small vehicles is getting more and more popular among two- and three-wheelers ranging from pedal-assist e-bikes to e-scooters and motorbikes. DC brushless (BLDC) motors are generally used for traction due to their efficiency, size and reliability. Typical power for pedal-assist e-bikes ranges from 250 to 500 W, while for e-scooters, motorbikes and three-wheelers power can reach up to 5 kW and more. The other key element that affects system performance (autonomy, motor power, etc.) are batteries which have typical voltages ranging from 24 up to 72 V. 48V batteries are becoming the most common choice especially for e-scooters. Battery voltage as well motor power are instrumental for correct IC selection.
ST offers an AEC-qualified integrated chipset for the ECU (Electronic Control Unit) up to 48V electric BLDC traction motors
The key building blocks of ST’s proposal are an SPC5 32-bit automotive MCU based on the Power Architecture family, an L9907 BLDC pre-driver and 100V MOSFETs for the bridge-inverter implementation. Particularly suitable for motor control applications, the SPC560P automotive MCU includes specific peripherals such as 6-channel PWM outputs (FlexPWM) which can be used to control each single phase of a 3-phase BLDC motor, two ADCs whose shared signal can acquire the 3-phase current and a Cross Timer Unit (CTU) to completely avoid having to use the CPU for in-time acquisitions of the state variables during the control cycle (PWM cycle, half PWM cycle or number of PWM cycles).
The L9907 is able to drive 6 MOSFET transistors for 3-phase BLDC motor applications. The circuit is suitable for operation in environments with a high supply voltage such as double-battery or 48V systems. Supply-related pins are capable of withstanding up to 90 V. Moreover, the L9907 is able to control its six pre-driver channels independently. In this way it is possible to implement all kinds of electric motor control strategies. The device offers programmability for a base gate output current via an external resistor. It is possible to select among 4 gate output current levels though the SPI bus even while the application is running. All channels are protected against short-circuits and the device is protected against over-temperature conditions.
A wide selection of 100V N-channel power MOSFETs with different output currents and RDS(on) according to application requirements is also part of ST’s product portfolio.
Each component has its own development toolchain and set of collaterals; a complete motor demonstrator based on this chipset equipped with a FOC control library is also available.
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The SPC5-MCTK-LIB FOC (Field oriented Control) Library is a software library specifically developed for SPC5 microcontroller family to control Automotive BLDC motor control applications. The library is also configurable via the SPC5-Studio development environment.
Collaterals also include dedicated application notes (see below).
Resources
