US 5,631,528 A · Elimination of motor negative voltages during motor brake

Abstract

A method for sensing motor commutation pulses during motor braking without creating negative voltages, which some junction isolated technologies substantially cannot tolerate. For instance, a commutation pulse sensing circuit containing junction isolated technology may only be able to detect commutation pulses intermittently. An H-bridge motor drive configuration is used to drive and brake a motor. High side clamp diodes are coupled between the motor terminals and a high potential source for high side braking of the motor. As an alternative to high side clamp diodes, any other suitable device may be used, including operating the pair of transistors in the upper portion of the H-bridge in an inverse mode. A commutation pulse sensing circuit is coupled to a terminal of the motor. The use of the high side brake clamp diodes avoids generating negative voltages at the motor terminals.

Claims16

Dependent claims

A method for elimination of motor negative voltages and sensing positive braking during braking of a motor, having a first and a second terminals, by use of a high and a low potential terminals, wherein, in a drive mode, current is driven from the first terminal to the second terminal of the motor, the method comprising the steps of:

coupling the second terminal of the motor to the high potential terminal;
coupling a diode from the first terminal of the motor to the high potential terminal, the diode being connected such that the diode's forward current is from the first terminal of the motor to the high potential terminal;
and
coupling a commutation pulse sensing circuit employing junction isolation technology to one of the first and second motor terminals.

1 more element

An apparatus for sensing commutation pulses by elimination of motor negative voltages during braking of a motor having a first and a second terminals by use of a high and a low potential terminals, wherein, in a drive mode, current is driven from the first terminal to the second terminal of the motor, the apparatus comprising:

a first diode coupled between the first terminal of the motor and the high potential terminal, the diode being capable of carrying a forward current and being connected such that the diode's forward current is from the first terminal of the motor to the high potential terminal;
a first switch coupled between the second terminal of the motor and the high potential terminal, the first switch being switchable between the first and second states:
a commutation pulse sensing circuit using junction isolated technology coupled to the second terminal of the motor, the commutation pulse sensing circuit being substantially incapable of tolerating negative voltages.

Dependencies are inferred from the claim text.

Elimination of motor negative voltages during motor brake

Life of this patent

Elimination of motor negative voltages during motor brake

Life of this patent

Abstract

Claims16