Control method for induction motors

• US 4,503,376 A
• Filed: 10/04/1983
• Issued: 03/05/1985
• Est. Priority Date: 10/04/1982
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Okuyama, Toshiaki
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US06/538,793
• Time in Patent Office: 518 Days
• Field of Search: 318/800, 318/802, 318/803, 318/807-811, 318/798, 318/805, 318/806
• US Class Current: 318/802
• CPC Class Codes: H02P 21/18 Estimation of position or speed
• CPC Class Codes: H02P 21/26 Rotor flux based control
• CPC Class Codes: H02P 2207/01 Asynchronous machines

Abstract

A quick response vector control method which is one of methods for controlling a speed of an induction motors without a speed detector; in which a voltage of the motor is detected to resolve into a vector component e_d parallel with an exciting current component vector of a primary current and a vector component e_q orthogonal to said exciting current component vector, and a frequency of the primary current is controlled to maintain the vector component e_d at zero, while at the same time the primary current is controlled corresponding to a difference between the vector component e_q and the speed command signal.

Claims

1. A vector control method for induction motor for independently controlling a torque current component and an exciting current component of the primary current supplied to an induction motor through the control of an amplitude and a frequency of the primary current, comprising the steps of:

detecting a motor voltage of said induction motor;

resolving said motor voltage into a vector component e_d parallel with an exciting current component of the primary current and a vector component e_q orthogonal to said exciting current component vector; and

controlling a frequency of said primary current so that said vector component e_d of said motor voltage is zeroed, while at the same time controlling said primary current corresponding to a difference between said vector component e_q and a speed command signal, thereby to control the speed of said induction motor.

2. A vector control method according to claim 1, further comprising the step of detecting a difference between said vector component e_q and a command value of said vector component e_q, thereby to automatically set said vector component e_q equally to said command value by controlling said exciting current component.

3. A vector control method according to claim 1, further comprising the step of adding a signal component corresponding to a slip frequency to said speed command signal to provide another speed command signal.

4. A vector control method according to claim 1, further comprising the step of adding a signal component corresponding to a slip frequency in negative polarity to a negative terminal of a speed difference amplifier.