Power conversion device and overcurrent protection circuit

Abstract

The invention provides a power conversion device and an over-current protection circuit, damage of a capacitor for smoothing contained in a dc part of a power conversion device for providing an ac generated by a conversion dc to an electromotor and driving the electromotor is prevented, and a semiconductor switch for change-over is protected from being destroyed by over-current. The power conversion device is provided: a power conversion part converting the dc input from a dc power supply to an ac via conversion operation and supplying the ac to the electromotor; a current detection part detecting current supplied from the power conversion part to the electromotor; an over-current detection part comparing a current detected by the current detection part and a threshold value for determining whether an over-current protection function is started, wherein when the former exceeds the latter, an over-current detection signal is output; and a conversion operation control part, with the over-current detection signal received from the over-current detection part as a moment, stopping conversion operation of the power conversion part; and a threshold value setting part setting a threshold value.

Description

technical field [0001] The present invention relates to a power conversion device that converts DC power into AC power, supplies it to an AC motor, and performs drive control of the AC motor. Background technique [0002] In recent years, electric vehicles that use AC motors (hereinafter referred to as "motors") as power sources and hybrid vehicles that use both electric motors and internal combustion engines have rapidly spread in response to increased attention to environmental issues. This is because electric motors do not emit CO2 like internal combustion engines, helping to cut CO2 emissions. Figure 13 It is a graph showing an example of the speed-torque characteristic of an electric motor for an electric vehicle or a hybrid vehicle. This kind of motor has a wide operating speed range, maintains a given large torque at low speeds, and gathers torque and maintains given power at high speeds. In addition, in electric vehicles and hybrid vehicles, braking operation in wh...

AI Technical Summary

Problems solved by technology

Therefore, in power conversion devices for electric vehicles and hybrid vehicles, when the overcurrent protection function is activated, the voltage between the electrodes of the smoothing capacitor included in the DC unit must not exceed the withstand voltage of the capacitor. insufficient attention was paid to this

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