Motor Duty Limit Control to Prevent Stall and Overcurrent

The duty ratio upper limit value is made dynamic rather than fixed. The control device adjusts the duty ratio upper limit value based on the detected rotation speed of the motor. When rotation speed is high, a higher duty ratio upper limit value is permitted; when rotation speed is low, the duty ratio upper limit value is restricted. This dynamic adjustment resolves the contradiction by allowing high duty ratios only when the motor is already rotating at sufficient speed, preventing excessive current during startup while enabling strong acceleration capability when safe.

The control device changes the parameter (duty ratio upper limit value) based on another parameter (rotation speed). By establishing a relationship where the duty ratio upper limit value is determined by the current rotation speed, the system optimizes motor performance across different operating conditions. This parameter change strategy allows the system to prevent excessive current at low speeds while enabling aggressive acceleration at higher speeds.

The system dynamically adjusts the duty ratio upper limit value based on real-time rotation speed detection. During motor startup when rotation speed is low, the duty ratio upper limit is restricted to prevent excessive current. Once the motor reaches sufficient rotation speed, the duty ratio upper limit is increased to provide the torque needed to overcome applied loads. This dynamic approach maintains both current safety and reliability under varying operating conditions.

The control device performs preliminary action by gradually increasing the duty ratio upper limit value as the motor accelerates. Rather than immediately applying high duty ratios that could cause current damage, the system progressively increases the duty ratio upper limit as rotation speed increases, preparing the motor for higher power demands before they are needed, thus preventing both current damage and stalling.