Independent pathways for detecting fault condition in electric motor

Patent metadata

Field	Value
Publication number	US-9735726-B2
Application number	US-201514967056-A
Country	US
Kind code	B2
Filing date	Dec 11, 2015
Priority date	Jun 25, 2014
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

An electric motor system having substantially independent hardware-based and software-based pathways for detecting and initiating responses to fault conditions, such as over-current conditions, in an electric motor which is powered by a power inverter which is controlled by a power module and a microprocessor. Each pathway involves comparing a voltage, which is representative of an electric current flowing to the motor, to a predetermined maximum voltage, and if the former exceeds the latter using hardware or software to initiate shutting off the motor, such as by shutting off the power inverter. When one pathway detects a fault condition it may notify the other pathway, and the notified pathway may also initiate shutting off the motor.

First claim

Having thus described one or more embodiments of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:

1. A motor control system for controlling an electrical motor, including detecting and responding to a fault condition in the electric motor, the motor control system comprising:
a first pathway for detecting and responding to the fault condition, the first pathway including—
a power module configured to generate a driving waveform to power the electric motor,
a power inverter configured to convert direct current power to alternating current power at a frequency and an amplitude to power the electric motor, and
a first resistor block configured to generate a first voltage signal that is representative of an electric current flowing to the electric motor,
wherein the power module compares the first voltage signal to a first predetermined maximum voltage signal, and if the first voltage signal exceeds the first predetermined maximum voltage signal the first pathway shuts off the electric motor; and

a second pathway for detecting and responding to the fault condition, the second pathway including—
a microprocessor connected to the power module, and configured to control operation of the power module and the electric motor, and
a second resistor block configured to generate a second voltage signal that is representative of the electric current flowing to the electric motor,
wherein the microprocessor compares the second voltage signal to a second predetermined maximum voltage signal, and if the second voltage signal exceeds the second predetermined maximum voltage signal the second pathway shuts off the electric motor,

wherein the first pathway and the second pathway are configured to substantially independently detect and respond to the fault condition, and
wherein the first resistor block and the second resistor block are the same resistor block, the first voltage signal and the second voltage signal are the same voltage signal, and the first predetermined maximum voltage signal and the second predetermined maximum voltage signal are the same maximum voltage signal.

2. A motor control system for controlling an electrical motor, including detecting and responding to a fault condition in the electric motor, the motor control system comprising:
a first pathway for detecting and responding to the fault condition, the first pathway including—
a power module configured to generate a driving waveform to power the electric motor,
a power inverter configured to convert direct current power to alternating current power at a frequency and an amplitude to power the electric motor, and
a first resistor block configured to generate a first voltage signal that is representative of an electric current flowing to the electric motor,
wherein the power module compares the first voltage signal to a first predetermined maximum voltage signal, and if the first voltage signal exceeds the first predetermined maximum voltage signal the first pathway shuts off the electric motor; and

a second pathway for detecting and responding to the fault condition, the second pathway including—
a microprocessor connected to the power module, and configured to control operation of the power module and the electric motor, and
a second resistor block configured to generate a second voltage signal that is representative of the electric current flowing to the electric motor,
wherein the microprocessor compares the second voltage signal to a second predetermined maximum voltage signal, and if the second voltage signal exceeds the second predetermined maximum voltage signal the second pathway shuts off the electric motor,

wherein the first pathway and the second pathway are configured to substantially independently detect and respond to the fault condition, and
wherein the first predetermined maximum voltage and the second predetermined maximum voltage are adjustable.

3. The motor control system as set forth in claim 1 , wherein the electric motor is a permanent magnet motor or an induction motor.

4. The motor control system as set forth in claim 1 , wherein the motor control system is incorporated into a machine selected from the group consisting of: heating and air conditioning machines and household and commercial appliance machines, and the electric motor drives a load selected from the group consisting of: blowers, pumps, and fans.

5. The motor control system as set forth in claim 1 , wherein the fault condition is an over-current condition in which too much current is flowing to the electric motor.

6. The motor control system as set forth in claim 1 , wherein the fault condition is selected from the group consisting of: An over-current condition, an under-current condition, an over-voltage condition, an under-voltage condition, an over-temperature condition, and an under-temperature condition.

7. The motor control system as set forth in claim 1 , wherein the first predetermined maximum voltage and the second predetermined maximum voltage are adjustable.

8. The motor control system as set forth in claim 1 , wherein both the first pathway and the second pathway shut off the electric motor by shutting off the power inverter.

9. The motor control system as set forth in claim 1 , wherein—
the first pathway further responds to the detected fault condition by notifying the second pathway of the detected fault condition, and
the second pathway further responds to the detected fault condition by notifying the first pathway of the detected fault condition.

10. The motor control system as set forth in claim 9 , wherein—
the first pathway responds to being notified by the second pathway of the detected fault condition by shutting off the electric motor, and
the second pathway responds to being notified by the first pathway of the detected fault condition by shutting off the electric motor.

11. A motor control system for controlling an electrical motor, including detecting and responding to a fault condition in the electric motor, the motor control system comprising:
a hardware-based pathway for detecting and responding to the fault condition, the hardware-based pathway including—
a power module configured to generate a driving waveform to power the electric motor,
a power inverter configured to convert direct current power to alternating current power at a frequency and an amplitude to power the electric motor, and
a resistor block configured to generate a voltage signal that is representative of an electric current flowing to the electric motor,
wherein the power module compares the voltage signal to a predetermined maximum voltage signal, and if the voltage signal exceeds the predetermined maximum voltage signal the hardware-based pathway shuts off the electric motor; and

a software-based pathway for detecting and responding to the fault condition, the software-based pathway including—
a microprocessor connected to the power module, and configured to control operation of the power module and the electric motor, and to compare the voltage signal to the predetermined maximum voltage signal, and if the voltage signal exceeds the predetermined maximum voltage signal the software-based pathway shuts off the electric motor,

wherein the hardware-based pathway and the software-based pathway are configured to substantially independently detect and respond to the fault condition, and
wherein the first predetermined maximum voltage and the second predetermined maximum voltage are adjustable.

12. The motor control system as set forth in claim 11 , wherein the electric motor is a permanent magnet motor or an induction motor.

Assignees

• Nidec Motor Corp

Inventors

• Glenn Douglas D
• Schock Christopher D

Classifications

• H02H7/0852

  directly responsive to abnormal temperature by using a temperature sensor (in a control circuit H02H7/0833) · CPC title

• H02H7/0838

  with H-bridge circuit · CPC title

• H02H5/041

  additionally responsive to excess current (H02H5/048 takes precedence) · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02H3/20

  responsive to excess voltage · CPC title