20A/40V Integrated Power Module for DC Brushless Motors (BLDC)

Rajkumar Sharma
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SKU: EL93630
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This project is based on STK984-090A which is a fully-integrated inverter with current rating 20A and supply voltage 40V DC. It has been designed to drive the Brushless DC Motors (BLDC) and permanent magnet synchronous motors (PMSM), the module works as output driver which include power stage and current sense circuitry, header connector provided to interface with Arduino or other micro-controller for PWM inputs and current feedback. Screw terminals help to connect the motor and power supply. INA168 IC is a current sensor and measures the current across the internal sense resistor and provides an output voltage. This voltage can be feed to Arduino analog pins to detect the current flowing across the MOSFET’s. LM317 voltage regulator provides 5V DC to power the current sense IC INA168 and other logic circuitry. D1 motor power LED. Maximum PWM frequency 20 KHz and duty cycle 10 to 90 % or 100%.

Note: This board is compatible with our Development board for Brushless Motor, DC Brushed Motor, AC Motors (Pre-Driver)

Current Feedback Output

The device INA168 converts a differential input voltage to a current output. This current is converted back to a voltage with an external load resistor that sets any gain from 1 to over 100.

Current feedback Output voltage can be set using this formula V = Current x 3mohms x R1/5K ohms ( Is.Rs.RL/5Kohms )

Note : 3mOhms Internal Shunt Resistor of STK984-090A

Output Voltage Range

The output of the INA168 device is a current that is converted to a voltage by the load resistor, R1, RX. The output current remains accurate within the compliance voltage range of the output circuitry. The shunt voltage and the input common-mode and power-supply voltages limit the maximum possible output swing. The maximum output voltage (Vout max) compliance is limited by either Equation (Vout max = VIN– – 0.5 V )

The project is a fully-integrated inverter power stage consisting of the gate driver, 6 Mosfets and high side current shunt resistor, suitable for driving permanent magnet synchronous motors and brushless DC (BLDC) motors. The MOSFETs are configured in a 3-phase bridge with a single drain connection for the lower legs. The power stage has a full range of protections including cross conduction protection, external shutdown and under-voltage lockout. Built-in charge pump for operation with low battery voltage, over current protection on both high side and low side Mosfets, over-temperature shutdown, under-voltage and over voltage shutdown for defined operation at all input voltages, integrated high side resistor for external current sensing.

Note: Refer to STK984-090A datasheet below for more information, C7-C12 capacitors are optional used as RC filters and recommended in a noisy environment. Required large size heat sink for peak load.