Autonatomy / Semiconductors & Electronic Switching / 09

Power Electronics &
Automotive Applications

Switch it. Convert it. Control it. Trace how MOSFETs, diodes, inductors, and capacitors work together to deliver electrical power — then diagnose what happens when a power stage fails.

10 guided lessons4 interactive experiments5 diagnostic cases12 V teaching models

Your mission

An ECU often cannot simply connect an actuator to the battery and hope for the best. Power-electronic circuits switch and manage energy to regulate voltage, current, motor torque, and electrical power.

Safety & scope: Every lab here is a simplified, isolated, low-voltage computer model — not a vehicle service procedure or a circuit-building instruction. Actual switching converters have inductive transients, heat, protection circuitry, and complex control loops. Automotive traction inverters and HV battery circuits can be lethal. Do not use this page to probe, build, or service a high-voltage system; follow OEM procedures and required training.
01Switch
Semiconductor drivers rapidly connect and disconnect electrical paths.
02Store & transfer
Inductors and capacitors redistribute energy between switching intervals.
03Verify
Compare the command, actual input power, output voltage, and load response.

10 guided lessons

Open each topic, read its application and technician note, then mark it complete.

DC–DC Converter Workbench

A buck converter ideally lowers DC voltage; a boost converter ideally raises it. Both rapidly switch an inductor to move energy into an output filter. Select a topology and adjust the controls to test its behavior.

DC inputSwitching stageL + C energy stageDC outputBATTERY12.0 VMOSFET +diodeINDUCTORCAPACITORLOAD6.0 VBuck: approximate ideal output Vout = duty × Vin (continuous conduction).Functional blocks only; switch, diode, and inductor placement differs between topologies.
The models assume an ideal switch and output filter for the voltage relationship and a user-selectable overall efficiency for input power. Ripple equations assume steady-state continuous inductor current, an ideal capacitor, and negligible ESR. They are educational approximations, not component-selection guidance. Select a light load to discover where continuous conduction no longer holds.

Configure the converter

Simulated steady-state readings

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Output voltage (ideal CCM)
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Output current
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Output power
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Estimated input current
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Estimated inductor current ripple (p-p)
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Estimated capacitive voltage ripple (p-p)

Switching and inductor-current traces

Top: switch command. Bottom: ideal triangular inductor-current ripple. When the inductor current would fall to zero, the triangular model is outside its valid operating region.

12 V Motor Driver Workbench

A MOSFET motor driver delivers rapid voltage pulses. Changing PWM duty changes the average applied voltage; actual motor speed and torque also depend on load, back-EMF, winding resistance, inertia, and control strategy.

FUSEMOTORMMOSFETECU / PWM+12 VConcept only: real flyback clamp / driver topology and wiring must follow manufacturer design.
Flyback matters: A motor is inductive. Current may continue during OFF intervals through appropriately designed recirculation or clamp paths. The simple chart below shows command and motor-terminal voltage pulses, not a measured real motor-current waveform. Never add a diode or bypass protection on a vehicle circuit based only on this illustration.

Driver controls

Command versus actual output

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ECU requested ON time
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Actual ON time
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Average applied voltage*
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PWM period

*Average of a simplified ideal motor-terminal pulse train relative to the modeled return. This is not a prediction of motor speed, torque, or real OFF-state voltage.

Scope · ECU command and terminal voltage

Inverter / H-Bridge Concept Lab

A four-switch H-bridge can reverse the polarity applied to a load. With alternating switch pairs, a DC source can produce a bipolar AC-like output. Automotive traction inverters commonly use controlled three-phase outputs, not the simple single-phase resistive example shown here.

Q1Q2Q3Q4LOADDC +DC −Do not turn on both switches in one leg simultaneously.Simplified single-phase H-bridge; no physical gate-driver instructions.
Critical concept — shoot-through: Turning on the high-side and low-side devices in the same bridge leg can short the DC bus. Real systems use gate-driver interlocks, dead time, current sensing, and fault protection. This simulation intentionally does not expose unsafe switching combinations.

Configure the H-bridge model

Calculated output · resistive load

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Output RMS voltage
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Resistive load power
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Positive half-cycle state
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Negative half-cycle state

Output waveform · two fundamental periods

The output is an ideal stepped bipolar voltage, not a sine wave. AC-machine inverters use more complex PWM and three-phase control; their actual currents depend on motor inductance and back-EMF.

The Challenger · Power Stage Diagnostics

Do not replace a converter or module based only on an output symptom. First gather evidence to separate input power, commanded switching, output voltage, and actual load condition. Each case uses a fictional, simplified 12 V circuit.

Reveal the measurements before choosing an explanation.

Final Knowledge Check

Answer all five questions. Four correct answers pass; finish the 10 lessons, four labs, and five case studies to unlock the course badge. Incorrect answers show an explanation so you can review and try again.