Electric Tricycle Motor Controller: Principles and Fault Diagnosis

The controller is the brain of the trike,managing power flow from the battery to the motor based on rider input.

1.Working Principles(Simplified)

The controller converts DC battery power into AC for the motor.

Core Process:The Microcontroller(MCU)reads the throttle position and motor position sensors(Hall sensors).It then sends signals to a Gate Driver,which rapidly switches high-power MOSFETs on and off.This switching creates the AC waveform that spins the motor.

Key Functions:

DC-DC Converter:Steps down high battery voltage to low voltage(e.g.,5V,12V)to power the MCU and sensors.

PWM(Pulse Width Modulation):The MCU controls motor speed by varying the"on"time of the power switches.More"on"time equals more power.

Commutation:The MCU uses Hall sensor feedback to know when to switch power between the motor's three phases,keeping it turning.

2.Common Symptoms&Quick Checks

Vehicle Dead(No Power):

Check:Main fuse,key switch,and large battery connections.

Motor Doesn't Run(Lights Work):

Check:Throttle signal(voltage should rise smoothly when twisted).Brake lever switch(may be stuck in"on"position).

Motor Runs Rough/Jerks:

Check:Connections on the three thick motor phase wires.Test Hall sensors(see below).

Overheating/Shuts Down:

Check:Vehicle overloaded,poor ventilation,or internal MOSFET failure.

Reduced Speed/Power:

Check:Weak or old battery,throttle not reaching full voltage.

3.Simple Diagnostic Flow

Visual:Look for loose wires,burns,or damage.

Power:Measure battery voltage at controller input.

Throttle:Probe signal wire;voltage should increase smoothly from~1V to~4V when twisted.

Hall Sensors:With power on,probe the three signal wires.Manually turn the wheel.A good sensor will pulse between 0V and 5V.A stuck value means a bad sensor.

MOSFETs(Diode Test-Power Off):

Multimeter on diode setting.

Put black probe on battery positive(+).Touch each motor phase wire with red probe.You should see a voltage drop(~0.5V).A short(0V)or open(OL)means a blown MOSFET.

Repeat with red probe on battery negative(-)and black probe on phases.You should again see a voltage drop.