Electronic Control Circuit Comprising Power Transistors And Method For Monitoring The Service Life Of The Power Transistors

• US 20140253170A1
• Filed: 11/21/2011
• Published: 09/11/2014
• Est. Priority Date: 11/21/2011
• Status: Active Grant

• Current Assignee: Ebm-Papst Mulfingen GmbH & Company KG
• Original Assignee: Ebm-Papst Mulfingen GmbH & Company KG
• Inventors: Lipp, Helmut, Haas, Gnter, Brkert, Martin
• Granted Patent: US 9,529,038 B2
• Time in Patent Office: Days
• US Class Current: 324/762.01
• CPC Class Codes: G01R 31/2642 Testing semiconductor operation lifetime or reliability, e.g. by accelerated life tests
• CPC Class Codes: G01R 31/282 Testing of electronic circuits specially adapted for particular applications not provided for elsewhere G01R31/2801 and G01R31/2851 take precedence
• CPC Class Codes: G01R 31/42 AC power supplies
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output

Abstract

The disclosure relates to an electronic control circuit for an electric device, in particular designed as a commutation electric system of an EC motor, having a plurality of power transistors which are controlled in an operating mode for controlling the device. An additional, similar, non-charged reference transistor in the operating mode of the power transistors is arranged or formed together with the power transistors on a common support or substrate. The circuit also comprises means for applying to the reference transistor and at least one power transistor, respectively one test flow in a test mode for measuring the respective associated saturation voltage and for evaluating saturation tension differences resulting from the measured saturation voltages of the reference transistors and the respective power transistors taking into account the temperature of the support/substrate produced during the measurement as the criterion for an aging process and an expected remaining service life of the power transistors. The disclosure also relates to a method for monitoring power transistors in said type of electronic control circuit with respect to the expected remaining service life thereof.

Claims

1. An electronic control circuit for an electrical device, in particular designed as a commutation electronic system of an EC motor, having a plurality of power transistors, which are controlled in an operating mode to control the device,

wherein an additional, similar reference transistor which is non-charged in the operating mode of the power transistors and is arranged or formed together with the power transistors on a common support or substrate, and by means for applying to the reference transistor and at least one of the power transistors respectively a test current in a test mode and for measuring the respective associated saturation voltage and for evaluating a saturation voltage difference resulting from the measured saturation voltages of the reference transistor and the respective power transistor taking into account the prevailing temperature of the support/substrate during the measurement as a criterion for an ageing process and an expected remaining service life of the power transistors.

2. The control circuit according to claim 1,

wherein additional means for evaluating a rate of change of the saturation voltage differences recorded in each of the respective consecutive test modes are provided.

3. The control circuit according to claim 1,

wherein an electronic control unit to trigger and perform the respective test mode.

4. The control circuit according to claim 1,

wherein the respective power transistor and the reference transistor may be connected to a constant current source in order to be supplied with the test current or to a DC voltage intermediate circuit via a resistor.

5. The control circuit according to claim 1,

wherein the transistors can be supplied individually and consecutively with the test current via a commutator.

6. The control circuit according to claim 1,

wherein the transistors can be supplied simultaneously with the respective test current via a multiple switch.

7. The control circuit according to claim 1,

further comprising means for storing to store certain empirical values of the saturation voltage difference and preferably its rate of change assigning them to certain stages of an ageing process of the power transistors and taking into account the temperature of the support/substrate.

8. The control circuit according to claim 1,

further comprising means for displaying the remaining service life and/or to generate a warning signal for an impending failure of at least one of the power transistors.

9. The control circuit according to claim 1,

four or six power transistors are arranged in series in pairs on respective bridge branches, which are parallel to each other, of a bridge circuit, the saturation voltage being measured in the/each test mode on at least one of the two power transistors of each bridge branch, in particular only on the so-called low side transistors of each bridge branch, and included in the evaluation.

10. A method for monitoring power transistors in an electronic control circuit for an electrical device, in particular in a commutation electronic system of an EC motor, with respect to the expected remaining service life, the method comprising

measuring the saturation voltage for at least one of the power transistors in a test mode of the control circuit and

comparing the saturation voltage for the at least one of the power transistors with the saturation voltage of an additional, similar, reference transistor, which is non-charged in the operating mode of the control circuit and is arranged or formed together with the power transistors on a common support or substrate, likewise measured under the same conditions, wherein a resultant saturation voltage difference is evaluated, taking into account the prevailing temperature of the support/substrate during the measurement as a criterion for the advance of the ageing process and for the expected remaining service life of the power transistors.

11. The method according to claim 10,

wherein a rate of change of the saturation voltage differences is also recorded in the respective test modes, which are carried out consecutively, and evaluated as a criterion for the remaining service life.

12. The method according to claim 10,

wherein the respectively determined saturation voltage differences and preferably their rates of change are compared to stored empirical values characterising an ageing process, taking into account the temperature of the support/substrate.

13. The method according to claim 10,

wherein a signal for displaying the remaining service life and/or an impending end to the service life of the power transistors is generated with reference to the evaluation of the respective saturation voltage when a certain value of the saturation voltage difference and/or its rate of change is reached.

14. The method according to claim 10,

wherein the test mode of a control unit is triggered and carried out before every operation of the control circuit and/or at certain intervals during operation by switching from the operating mode, and wherein switching to the operating mode takes place subsequent to the/each test mode.

15. The method according to claim 10,

wherein the saturation voltages of each of a plurality of power transistors of the control circuit are measured in the test mode, wherein the power transistor with the greatest saturation voltage difference and/or the highest rate of change is regarded as definitive for the advance of the ageing process and the expected remaining service life of the power transistors.

16. The method according to claim 10,

wherein the measurements of the saturation voltages of the power transistors and of the reference transistor are carried out consecutively or simultaneously.

17. The method according to claim 10,

wherein the respective power transistor and the reference transistor are supplied similarly with a test current from a constant current source or from a DC voltage intermediate circuit via a resistor.