Driving circuit for a switched reluctance motor

• US 5,896,020 A
• Filed: 05/30/1997
• Issued: 04/20/1999
• Est. Priority Date: 06/28/1996
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Pyo, Sang-Yeon
• Primary Examiner(s): Sircus, Brian
• Application Number:
  US08/866,079
• Time in Patent Office: 690 Days
• Field of Search: 318/696, 318/685, 318/254, 318/439, 318/138, 318/701
• US Class Current: 318/701
• CPC Class Codes: H02H 7/0833 for electric motors with control arrangements
• CPC Class Codes: H02P 25/08 Reluctance motors
• CPC Class Codes: H02P 25/098 Arrangements for reducing torque ripple
• CPC Class Codes: H02P 29/40 Regulating or controlling the amount of current drawn or delivered by the motor for controlling the mechanical load

Abstract

This invention provides a driving circuit for a switched reluctance motor(SRM) comprising a current sensing unit which senses current amount flowing into a driving circuit of the SRM and outputs a signal representing current amount flowing in the driving circuit, a comparing unit which compares a reference current amount with current amount flowing in the driving circuit in response to the output signal from the current sensing means, and outputs a stop signal in case the current amount flowing in the driving circuit of the SRM exceeds the reference current amount, and a signal selecting unit which receives output signal from the comparing means, a Pulse Width Modulated(PWM) signal and a rotor position signal, and outputs a gate controlling signal for turning off the switching element during an input of the stop signal from the comparing means. The protection of the driving circuit against the excess current according to the present invention improves reliability of the SRM, as well as eliminates the ripple component in the driving current(torque ripple) generated at the time of an initial start-up of each phase, which reduces loud noise of the motor.

Claims

1. A driving circuit for a switched reluctance motor having a plurality of phase coils, the driving circuit having a plurality of switching elements, operated in response to gate signals input from an external source, for applying a direct voltage to or cutting off a direct voltage from each of said phase coils, said driving circuit comprising:

current sensing means which senses current amount flowing in a driving circuit of said motor and outputs a signal representing said current amount flowing in the driving circuit;

comparing means for comparing a reference current amount with said current amount flowing in the driving circuit in response to the output signal from the current sensing means, and for outputting a stop signal when the current amount flowing in the driving circuit of said motor exceeds the reference current amount; and

signal selecting means for receiving output signals from the comparing means, a pulse width modulated signal and a rotor position signal, and for outputting a gate controlling signal for turning off the switching element during an input of the stop signal from the comparing means;

said current sensing means comprising a current sensing resistor, coupled to said driving circuit, for outputting a voltage signal proportional to a driving current value;

said comparing means comprising a variable resistor for determining a reference voltage, a capacitor for eliminating noise components contained in the voltage signal produced by the current sensing resistor, and an operational amplifier which outputs a low level signal when a voltage signal applied through the capacitor has a value larger than that of the reference voltage, and which outputs a high level signal when a voltage signal applied through the capacitor has a value smaller than that of the reference voltage; and

said signal selecting means comprising a first logic product gate which performs a logic product of the output signal from the comparing means and the rotor position signal and then produces a signal for controlling the gate of one of the switching elements, and a second logic product gate which performs a logic product of the output signal from the first logic product gate and the pulse width modulated signal and then produces a signal for controlling the gate of a further one the switching elements.