An inverter outputs the voltage of a rectangular waveform, with the amplitude of the high-voltage power supply voltage and ground level. The voltage increase rate (dv/dt) is very high, from 100V/µs – several kV/µs. Since wiring for low voltage signals [ 5V ], such as a Hall signals (HU, HV, HW terminals), speed signal (VSP terminal) and triangular wave signals (CR terminal), exists on the same board, noise may due to the high voltage dv/dt. Care should be taken to arrange PCB patterns to enhance EMI influence. It is also effective to add a capacitor or pull-up resistor to attain lower impedance wiring. Where large currents flow, such as the inverter output terminal, please consider a pattern to minimise stray inductance. Noise may be generated from the power supply system or ground wiring system leading to an over-voltage applied to IC which may lead to IC destruction. Care should be taken to apply noise suppression from external sources.
We recommend the application of a conformal coating or to mold the pin(s) of IC. There are various kind of coating resin. Resins can influence thermal and mechanical stress to semiconductor devices. When selecting a coating resin, please consult with the manufacturer.
Insulation voltage. Generally during an insulation voltage test of a motor, a voltage of several 1000V may be applied. As the maximum rating of an inverter IC is typically 500V-600V, when an insulated design is inadequate, over-voltage can be applied to the IC leading to destruction. The tab (cooling fin) and IC chip are connected to the GL terminal by a high resistance of several 100kΩ and insulation is not provided. When attaching the tab to a motor case, it is necessary to adopt appropriate insulation.
The tab (cooling fin) and IC chip are connected to the GL terminal by a high resistance of several 100kΩ and insulation is not provided. When attaching the tab to a motor case, it is necessary to adopt appropriate insulation.
The tab of the inverter IC does not need to be electrically connected to a potential. However, if connected to the ground of IC, for example, the floating capacity inside the IC may become large leading to incorrect operation. Floating is therefore the recommended route.
If wiring is long, noise and over-voltage may be applied to the IC. The IC may operate incorrectly or may be destroyed. Precautions to monitor each terminal and avoid over-voltage to the IC are advised. Surge voltage durability is not guaranteed. If the maximum rating voltage is exceeded, there is a possibility of causing degradation of IC and/or destruction.
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