CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2016/087223 filed Dec. 14, 2019.

TECHNICAL FIELD

This application relates to a control device for an electric motor, and can be applied to a control device of a generator motor which is mainly mounted on a vehicle, operates as an electric motor, during the start of the engine and the assisting torque, and also operates as a generator after the start of the engine.

BACKGROUND ART

In the recent years, in order to improve fuel economy and conforming to environmental standards, vehicles have been developed for the purpose of conformity with environmental standards, mounting a generator motor, stopping the engine when the vehicle is stopped and restarting the engine with the generator motor when starting the vehicle. Since the generator motor used for such vehicle is required to be compact, low cost, with a high torque, driving with square wave energization is often performed using a wound field type generator motor.

In the case of operating such electric motor with the electric power supplied from the battery, the battery voltage lowers because frequent excessive electric power supply is required. In addition, at low temperatures or when battery deterioration is advanced, the voltage reduction becomes particularly large. As a suppression means for this voltage reduction, a power supply control device provided in the vehicle system, a change in the power supply voltage predicted based on the battery state and the operation state of the electric load, and a current of the electric load limited by the load controller are proposed.

(See Patent Literature 1)

PRIOR ART DOCUMENT

Patent Literature

[Patent Literature 1] JP2004-194364A

DISCLOSURE OF INVENTION

Technical Problem

However, in Patent Document 1, as the installation of a power supply control device and a load controller for a conventional vehicle system are required, there are problems such as increase in number of man-hours for development, cost increase, space pressure, etc.

This application was made to solve the above-described problems, and it is an object of the invention to provide a control device for an electric motor that autonomously reduces the motor output based on the battery voltage.

Solution to Problem

The control device for an electric motor according to this application provides a battery voltage detecting part for detecting a battery voltage at the time of driving a motor driven by a battery, and a minimum voltage holding part for keeping the battery voltage above the predetermined voltage by reducing the consumption current of the electric motor when the battery voltage detected by the battery voltage detecting part falls below a predetermined voltage during driving of the electric motor, so that the battery voltage can be maintained above the predetermined voltage.

Advantageous Effects of Invention

According to this application, it is possible to suppress the voltage reduction of the battery during driving at low cost, and to keep the battery voltage above the predetermined voltage.

