Overtemperature warning cycle in operation of polyphase DC motors

• US 6,094,026 A
• Filed: 02/02/1994
• Issued: 07/25/2000
• Est. Priority Date: 08/28/1992
• Status: Expired due to Term

• Current Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Cameron, Scott W.
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US08/191,060
• Time in Patent Office: 2,365 Days
• Field of Search: 318/471, 318/434, 388/804, 388/805, 388/811, 388/812, 388/819, 388/814, 388/820, 388/903, 388/934, 361/23, 361/25, 361/27, 361/103, 361/105
• US Class Current: 318/471
• CPC Class Codes: H02H 5/044 using a semiconductor device to sense the temperature
• CPC Class Codes: H02H 7/0833 for electric motors with control arrangements
• CPC Class Codes: H02H 7/0858 by reversing, cycling or reducing the power supply to the motor
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: H02P 6/34 Modelling or simulation for control purposes

Abstract

A method and integrated circuit for providing drive signals to a polyphase dc motor. The integrated circuit is fabricated on a semiconductor substrate for providing drive signals to a polyphase dc motor. The circuit includes a coil drive circuit for connection to drive coils of the motor to selectively supply drive currents thereto in a predetermined sequence. A sequencer circuit commutatively selects the drive coils to which the drive currents are selectively supplied, and a motor, speed controlling circuit controls the speed of the motor by controlling the speed of commutation. A temperature sensing element, such as a diode, is fabricated in the substrate to indicate the temperature of the substrate, and a temperature measuring circuit is connected to the temperature sensing element and to the motor speed controlling circuit to operate the motor speed controlling circuit to slow the speed of the motor when the temperature of the substrate exceeds a first predetermined temperature. If desired, temperature measuring circuit can include a circuit for measuring a second temperature higher than the first predetermined temperature to operate a shut down circuit to turn off the motor if the substrate temperature is too high.

Claims

1. An integrated circuit fabricated on a semiconductor substrate for providing drive signals to a polyphase dc motor, comprising:

a driver for sequentially supply drive currents to drive coils of the motor;

a commutation controller for commutatively selecting, at first and second frequencies, the drive coils to which the drive currents are sequentially supplied by the driver, said first frequency being higher than said second frequency;

a temperature sensing element fabricated in said substrate to indicate the temperature of said substrate;

a temperature measuring circuit connected to said temperature sensing element and to said commutation controller, for causing the commutation controller to operate at the second frequency responsive to the temperature of the substrate exceeding a first threshold temperature and for subsequently causing the commutation controller to operate at the first frequency responsive to the temperature of the substrate falling below a second threshold temperature, the second threshold temperature being lower than the first threshold temperature, wherein said temperature measuring circuit comprises a comparator connected to receive a reference potential on one input and a voltage across the temperature sensing element on another input and wherein said comparator has a hysteresis characteristic corresponding to the difference between said second predetermined threshold temperature and said first predetermined temperature.

2. An integrated circuit fabricated on a semiconductor substrate for providing drive signals to a polyphase dc motor, comprising:

a coil driver circuit for sequentially supplying drive currents to drive coils of the motor;

a commutation controller for commutatively selecting, at first and second frequencies, the drive coils to which the drive currents are supplied by the coil driver circuit, said first frequency being higher than said second frequency;

a motor shut off circuit for shutting off the motor;

a temperature sensing element fabricated in said substrate to indicate the temperature of said substrate, wherein said temperature sensing element is a diode and further comprising a constant current source connected to supply current to said diode;

a temperature measuring circuit connected to said temperature sensing element, said temperature measuring circuit comprising;

a first temperature threshold circuit for producing a warm signal to said commutation controller responsive to the temperature of said substrate exceeding a first temperature threshold, said warm signal causing said commutation controller to operate at said second frequency when said first temperature threshold has been exceeded, said first temperature threshold circuit for inactivating said warm signal responsive to the temperature of the substrate falling below a second threshold temperature, causing said commutation controller to operate at said first frequency;

a second temperature threshold circuit for producing a hot signal to said motor shut off circuit responsive to the temperature of said substrate exceeding a third temperature threshold higher than said first temperature threshold, causing said motor shut off circuit to shut off the motor when said third temperature threshold has been exceeded,

wherein said temperature measuring circuit comprises first and second comparators connected to receive respective reference potentials on one input and a voltage across the temperature sensing element on another input and wherein each of said comparators has a hysteresis characteristic.