Introduction

A Mitsubishi Electric IPM brings the three-phase power stage, the drive circuit and the protection together in one package, which simplifies the drive design but still leaves several decisions to the designer: the control supply, the current-sense resistor, the protection thresholds and the thermal path. This application note explains those decisions for compact servo, inverter and compressor drives, so a design moves quickly from concept to a reliable board.

Control Supply and Interface

A Mitsubishi Electric IPM is designed to be driven directly by a microcontroller. It uses a dedicated control supply and accepts standard logic inputs, so it connects without level shifting. The control supply must be clean and well decoupled close to the module, because noise on the supply can disturb the drive circuit. The undervoltage protection shuts down the output if the supply sags below its threshold, then clears when the supply recovers, which protects the silicon from weak gate drive.

Input Logic and Dead Time

Inside the IPM, the dead time between the high-side and low-side switches is fixed and factory-tuned, so the designer does not generate it in software. This removes a common source of shoot-through failures in discrete designs and simplifies the microcontroller code. The input signals still need to respect the module's minimum pulse timing, so check the datasheet for the switching timing and the propagation delay before finalizing the control loop.

Short-Circuit Protection

An IPM detects a short circuit by sensing the current through the low-side switches. The designer selects an external current-sense resistor that sets the trip level. Size the resistor so the trip current sits above the motor's peak operating current with margin, but below the module's safe limit. A trip that is too low nuisance-trips on normal acceleration; a trip that is too high does not protect the module. After a trip, the module asserts a fault and latches off until the fault is cleared, so the controller should read the fault and shut down the motor cleanly before re-enabling.

Current and Temperature Sensors

Many Mitsubishi Electric IPM parts include built-in current and temperature sensors, which simplify the control loop and the thermal protection. The temperature information output lets the controller reduce load or improve cooling before the over-temperature threshold is reached, which improves reliability without extra sensing hardware.

Over-Temperature and Undervoltage

Undervoltage protection protects against a sagging control supply, and over-temperature detection monitors the module temperature and shuts down if it exceeds a safe threshold. Both conditions assert the fault output. The controller should treat the over-temperature fault as a warning to reduce load or improve cooling, and the undervoltage fault as a supply problem to investigate. The thermal protection is a last line of defence, not a normal operating condition.

Board Layout

Even with integrated protection, layout decides reliability and EMI. Mount the IPM flat against a clean, flat heatsink with a thin, uniform interface, and verify the case temperature at full load. Keep the DC-link capacitor close to the module power terminals to minimize the commutation loop, route the current-sense resistor with short leads, and keep high-current paths away from the low-level control signals. These habits keep EMI low and the protection reliable.

Cooling and Mounting

The IPM must dissipate the inverter loss through its case, so the thermal interface and the heatsink are as important as for a discrete design. Use the specified mounting torque, avoid an uneven or contaminated interface, and confirm the case temperature under the worst-case load and ambient. A marginal thermal path does not necessarily destroy the part because the module protects itself, but it limits output and hurts reliability.

Scaling Across the Family

The G1 and V1 series share a common interface concept, so a design can scale from a compact 50 A inverter to a high-current 200 A module without changing the control approach. When you move to a higher rating, re-check the current-sense resistor, the DC-link capacitor and the thermal design, but the microcontroller interface and firmware stay essentially the same. That consistency shortens development and reduces the risk of a redesign when the product range grows.

Conclusion

A Mitsubishi Electric IPM removes most of the power-stage engineering from the designer's task, leaving the control supply, the trip level and the thermal path to specify. Get those right, respect the layout and thermal rules, and the result is a compact, reliable drive that reaches production quickly.