Regenerative circuit for motor drive system having leakage current compensation

• US 5,034,669 A
• Filed: 06/18/1990
• Issued: 07/23/1991
• Est. Priority Date: 10/04/1989
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Sako, Akira, Tsutsumishita, Yoji
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): SALATA, ANTHONY J
• Application Number:
  US07/539,494
• Time in Patent Office: 400 Days
• Field of Search: 312/363, 312/375-378, 312/759-763, 312/87, 312/88, 318/379-381, 318/362, 318/366, 318/367, 318/63, 318/86, 318/794, 318/817
• US Class Current: 318/376
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02P 23/07 Polyphase or monophase asynchronous induction motors

Abstract

A regenerative control circuit for controlling the regenerative energy of an electric motor drive system includes a regenerative energy dissipating resistor connected in parallel to a main smoothing capacitor through a switching element, a comparator connected to the switching element and adapted to produce an output signal to drive the switching element, a regenerative reference voltage rectifying circuit connected to a 3-phase a.c. power source, a regenerative reference voltage smoothing capacitor connected to the output of the regenerative reference voltage rectifying circuit, and a regenerative circuit including a regeneration transistor for entering a voltage difference, which is created between the main smoothing capacitor and the regenerative reference voltage smoothing capacitor by regenerative energy in certain circumstance, to the comparator. The circuit operates to control the regenerative energy, while maintaining the voltage of the main smoothing capacitor constant.

Claims

1. A regenerative control circuit for an electric motor drive system which includes a rectifying circuit connected to a 3-phase a.c. power source, a main smoothing capacitor connected to the output of said rectifying circuit, and an inverter having an input thereof connected to said main smoothing capacitor and an output thereof connected to an electric motor, said regenerative control circuit comprising:

regenerative energy dissipating means connected in parallel to said main smoothing capacitor through a switching element;

a comparator connected to said switching element and adapted to produce an output signal to drive said switching element;

a regenerative reference voltage rectifying circuit connected to said 3-phase a.c. power source and adapted to produce a regenerative reference voltage;

a regenerative reference voltage smoothing capacitor connected to the output of said regenerative reference voltage rectifying circuit; and

a regenerative circuit including a regeneration transistor for inputting a voltage difference which is created between said main smoothing capacitor and said regenerative reference voltage smoothing capacitor by regenerative leakage current energy, to said comparator after biasing said voltage difference.

2. A regenerative control circuit according to claim 1, wherein said regenerative energy dissipating means comprises a resistor.

3. A regenerative control circuit according to claim 1, wherein said regenerative reference voltage rectifying circuit is formed of six diodes.

4. A regenerative control circuit according to claim 1, wherein said switching element comprises a transistor.

5. A regenerative control circuit for an electric motor drive system, comprising:

regenerative energy dissipating means for dissipating excess regenerative energy connected in parallel to a main smoothing capacitor of said electric motor drive system through a switching element;

comparator means for developing a switching element drive signal for driving said switching element;

means for developing a regenerative reference voltage;

a regenerative circuit for biasing a voltage difference between said main smoothing capacitor and said regenerative reference voltage means and applying said voltage difference to said comparator means to develop said switching element drive signal.

6. A regenerative control circuit for a motor drive system according to claim 5, wherein said regenerative circuit comprises:

a transistor having an emitter connected to said main smoothing capacitor, a collector connected to said comparator means, and a base connected to said regenerative reference voltage means.