Method and a control system for starting a motor

• US 7,345,859 B2
• Filed: 07/13/2006
• Issued: 03/18/2008
• Est. Priority Date: 07/15/2005
• Status: Active Grant

• Current Assignee: Secop GmbH (Nidec Corporation)
• Original Assignee: Danfoss Compressors, Spol. S R.O. (AURELIUS Equity Opportunities SE & Co. KGaA)
• Inventors: Thomsen, Rune, Andersen, Mads, Joergensen, Henrik, Pedersen, Niels
• Primary Examiner(s): Donovan; Lincoln
• Assistant Examiner(s): PAUL, ANTONY M
• Application Number:
  US11/486,201
• Publication Number:
  US 20070014056A1
• Time in Patent Office: 614 Days
• Field of Search: 361/28, 361/23, 318/102
• US Class Current: 361/23
• CPC Class Codes: H02H 3/006 Calibration or setting of parameters
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02H 3/093 with timing means in general H02H3/027; thermal delay H02H3/085; timing means for undervoltage protection H02H3/247
• CPC Class Codes: H02H 7/0816 concerning the starting sequence, e.g. limiting the number of starts per time unit, monitoring speed during starting
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/00304 Overcurrent protection

Abstract

A method for starting a battery driven motor, wherein an input voltage is measured continuously. In case the input voltage becomes smaller than a predefined minimum voltage the attempt to start the motor is stopped and the maximum permitted current level to be supplied from the battery to an electronic unit of the motor is lowered before the next attempt. This is repeated until the input voltage is larger than the minimum voltage and the motor is no longer in start-up mode. The method protects the battery from collapsing. The method is suitable for starting battery driven motors for driving compressors. The number of attempted start-up sequences may be counted and on the basis of this it may be determined that the battery is weak or that the wiring is misdimensioned. Furthermore, a control system for controlling starting of a motor.

Claims

1. A method of starting a motor, the method comprising the steps of:

(a) connecting a battery to input terminals at an electronic unit controlling the motor, thereby supplying a current to the electronic unit from the battery, the electronic unit ensuring that the supplied current does not exceed a predefined maximum current, I_max;

(b) at least substantially continuously measuring an input voltage, V_input, on the electronic unit input terminals, and comparing V_input to a predefined minimum voltage, V_min;

(c) in case V_input becomes smaller than V_min, stopping the motor and waiting for a predefined time interval;

(d) lowering the maximum permitted current level, I_max, to be supplied from the battery to the electronic unit; and

(e) repeating steps (b) through (d) until it is obtained that V_input≧

V_min and the motor is no longer in start-up mode.

2. The method according to claim 1, wherein V_min is chosen as the minimum voltage required in order to protect the battery from collapsing.

3. The method according to claim 1, further comprising the step of counting the number of times steps (b) through (d) are repeated.

4. The method according to claim 3, further comprising the step of determining, on the basis of the counting step, whether or not there is a fault on the battery.

5. The method according to claim 3, further comprising the step of determining, on the basis of the counting step, whether or not wiring between the battery and the electronic unit has been misdimensioned.

6. A control system for controlling starting of a motor by means of a battery, the control system comprising:

means for at least substantially continuously measuring an input voltage, V_input, on input terminals of an electronic unit controlling the motor, the input voltage being supplied by the battery,

means for comparing V_input to a predefined minimum voltage, V_min,

means for generating a stop signal to the motor in response to an output from the comparing means, and in case V_input becomes smaller than V_min, thereby stopping the motor, and

means for controlling the maximum permitted current level, I_max, to be supplied from the battery to the electronic unit in response to the stop signal.

7. The control system according to claim 6, wherein the means for controlling the maximum current level is or forms part of a microcontroller.

8. The control system according to claim 6, further comprising means for counting a number of attempted start sequences.

9. A starter assembly for a motor, the starter assembly comprising a control system according to claim 6.

10. The starter assembly according to claim 9, wherein the motor is adapted to drive a compressor.