Apparatus and method for motor current protection through a motor controller

• US 6,359,410 B1
• Filed: 02/22/2000
• Issued: 03/19/2002
• Est. Priority Date: 02/22/2000
• Status: Expired due to Fees

• Current Assignee: CEI Of Springfield, TN
• Original Assignee: Saia-Burgess Automotive Actuators LLC
• Inventors: Randolph, Bruce
• Primary Examiner(s): Masih, Karen
• Application Number:
  US09/510,548
• Time in Patent Office: 756 Days
• Field of Search: 318/599, 318/432, 318/434, 318/807, 318/808, 318/811, 318/812
• US Class Current: 318/599
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36

Abstract

The present invention provides a new limiting signal circuit configuration for the connection of a pulse-width modulation motor controller integrated circuit. This new circuit allows for increased control over the over-current protection scheme while increasing the maximum available current levels. The invention utilizes a resistor based voltage divider connected to an input power source to provide a sliding scale current limiting signal in proportion to the input voltage. This method provides protection in relationship to the incoming power signal.

Claims

1. An improved over-current protection circuit for a pulse width modulation motor controller, comprising:

a variable input voltage signal;

a ground signal;

a pulse width modulation motor control signal;

a motor current signal;

a current adjustment signal which sets a limit for said motor current signal;

an integrated circuit chip which selectively outputs said pulse width modulation motor control signal in proportion to said variable input voltage signal, said ground signal, said current adjustment signal and said motor current signal;

a first resistor, wherein said first resistor connects said variable input voltage signal and said current adjustment signal; and

a second resistor, wherein said second resistor connects said current adjustment signal and said ground signal,

whereby said first resistor and said second resistor control said current adjustment signal in proportion to said variable input voltage signal.

2. Said over-current protection circuit of claim 1, wherein:

said integrated circuit chip clips said pulse width modulation motor control signal whenever said motor current signal exceeds said limit.

3. Said over-current protection circuit of claim 1 wherein:

said variable input voltage signal includes a range between zero and 5 volts.

4. Said over-current protection circuit of claim 1, wherein:

said current adjustment signal is between zero and 4 volts.

5. Said over-current protection circuit of claim 1, wherein:

said integrated circuit chip is a DELCO ELECTRONICS CORPORATION 16214712.

6. Said over-current protection circuit of claim 1, wherein:

said first resistor and said second resistor are proportioned to set said current adjustment signal between 1 and 4 volts for a range of variable input voltage signal.

7. A method for adjustable over-current protection, comprising:

connecting an adjustable input voltage signal and a reference signal to an integrated circuit which selectively outputs a pulse width modulation motor control signal in proportion to the adjustable input voltage signal, the reference signal, and a current adjustment signal; and

generating said current adjustment signal in proportion to a difference between said adjustable input voltage signal and said reference signal.

8. Said method of claim 7, wherein:

said generating is performed by a voltage divider.

9. Said method of claim 8, wherein:

said voltage divider is formed from a first and second resistor connected in series.

10. A method for an improved protection circuit for a motor, comprising:

receiving a variable input voltage at a motor controller;

generating at the motor controller a motor control signal which controls an amount of power supplied to said motor;

monitoring said amount of power supplied to said motor;

deriving a motor power limit from said variable input voltage using a voltage divider;

monitoring the motor power limit at the motor controller and

changing said motor control signal to reduce said amount of power supplied to said motor when said amount of power exceeds said motor power limit.

11. An improved protection circuit for a motor controller, comprising:

a variable power supply signal;

a voltage divider which provides a power limiting signal in proportion to said power supply signal;

a motor power signal; and

an integrated circuit chip which outputs a motor control signal when said power limiting signal exceeds said motor power signal.

12. An improved apparatus for generating a motor limiting signal for a pulse width modulation motor control circuit utilizing an integrated circuit which accepts an input voltage signal, a ground signal, and a motor limiting signal, said improvement comprising:

a voltage divider means for generating said motor limiting signal in proportion to said input voltage signal.

13. Said improved apparatus of claim 12, wherein said voltage divider means includes:

a first resistor connected to said input voltage signal and an attachment point; and

a second resistor connected to said attachment point and said ground signal.

14. Said improved apparatus of claim 13, wherein:

said first resistor and said second resistor maintain a voltage level at said attachment point in proportion to said input voltage signal.

15. Said improved apparatus of claim 14, wherein:

said voltage level is maintained between zero and five volts.

16. Said improved apparatus of claim 12, wherein:

said motor limiting signal includes a voltage signal.

17. Said improved apparatus of claim 16, wherein:

said voltage signal includes voltages between zero volts and five volts.