CURRENT DRIVING SYSTEM FOR A SOLENOID

• US 20140238494A1
• Filed: 02/26/2013
• Published: 08/28/2014
• Est. Priority Date: 02/26/2013
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: SCHWEIKERT, Christian, SCHAEFER, Juergen
• Granted Patent: US 9,528,625 B2
• Time in Patent Office: Days
• US Class Current: 137/1
• CPC Class Codes: F02D 2041/2003 using means for creating a boost voltage, i.e. generation or use of a voltage higher than the battery voltage, e.g. to speed up injector opening
• CPC Class Codes: F02D 2041/2044 using pre-magnetisation or post-magnetisation of the coils
• CPC Class Codes: F02D 2041/2051 using voltage control
• CPC Class Codes: F02D 2041/2058 using information of the actual current value
• CPC Class Codes: F02D 2041/2068 characterised by the circuit design or special circuit elements
• CPC Class Codes: F02D 2041/286 comprising means for signal processing
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: F16K 31/0648 the armature and the valve member forming one element F16K31/0651 takes precedence
• CPC Class Codes: F16K 31/0675 Electromagnet aspects, e.g. electric supply therefor
• CPC Class Codes: H01F 7/064 Circuit arrangements for actuating electromagnets circuit arrangements for obtaining special operating characteristics H01F7/18; driving circuits for electromagnets making use of a switching regulator H01H47/325
• CPC Class Codes: Y10T 137/0318 Processes

Abstract

A current driving system for a solenoid valve is described herein. In an embodiment, the current driving system comprises a pre-driver to control a control input of a transistor coupled to an electrical input of a solenoid valve. The transistor inducts electric power into the solenoid valve when the transistor is switched on.

The current driving system further comprises a signal generator to produce a small signal and to output the small signal to the electrical input of the solenoid valve. The electric power being supplied by the small signal into the solenoid valve is substantially smaller than the electric power being supplied by the transistor when the transistor is switched on. The current driving system further comprises a measurement unit to measure a response to the small signal at the electrical input of the solenoid valve.

Claims

1. A current driving system for a solenoid valve, comprising:

a pre-driver to control a control input of a transistor coupled to an electrical input of a solenoid valve, wherein the transistor supplies electric power to the solenoid valve when the transistor is switched on;

a signal generator to generate a small signal and to output the small signal to the electrical input of the solenoid valve, wherein an amount of electric power of the small signal input to the solenoid valve is substantially smaller than an amount of the electric power supplied by the transistor to the solenoid valve when the transistor is switched on; and

a measurement unit to measure a response to the small signal.

2. The current driving system of claim 1, wherein the small signal is a periodic signal.

3. The current driving system of claim 1, wherein no small signal is coupled to the electrical input of the solenoid valve during the time in which the transistor drives current into the solenoid valve.

4. The current driving system of claim 1, wherein the coupling unit comprises:

a capacitor comprising a first electrode and a second electrode, wherein the first electrode is connected to an output of the signal generator, and wherein the second electrode is connected to the electrical input of the solenoid valve.

5. The current driving system of claim 1, wherein the measurement unit measures a frequency response at the electrical input.

6. The current driving system of claim 5, wherein the frequency response is within a range of substantially between 1 and 10 MHz.

7. The current driving system of claim 1, wherein the measurement unit comprises:

a comparator; and

a counter coupled downstream of an output of the comparator.

8. The current driving system of claim 1, wherein the pre-driver, the signal generator and the measurement unit are monolithically integrated in an integrated circuit.

9. The current driving system of claim 1, wherein the electric power supplied by the transistor to the solenoid valve when the transistor is switched on is at least ten times larger than the electric power being supplied by the small signal into the solenoid valve.

12. The current driving circuit according to claim 1, whereby no small signal is coupled to the output during the time in which the transistor drives current into the solenoid valve.

13. The current driving system of claim 1, further comprising:

a regulator for regulating the current through the solenoid valve by controlling the pre-driver;

a first feedback path to the regulator for providing a measurement of one or more of a voltage at the electrical input of the solenoid valve and a current through the solenoid valve; and

a second feedback path to the regulator for providing a measurement of the response to the small signal.

14. The current driving circuit according to claim 13, wherein the regulator bases the regulation on an impedance value of the solenoid valve, wherein the impedance value is based on the measured response to the small signal.

15. The current driving circuit according to claim 1, whereby the small signal has a frequency in the range of 5 to 10 MHz.

16. The current driving circuit according to claim 1, whereby the measurement unit comprises a sampling unit for sampling the response with sampling frequency between 100 and 200 MHz.

17. The current driving circuit according to claim 1, whereby the measurement unit comprises a zero crossing detection unit.

18. Method for controlling a solenoid valve, comprising:

generating a small signal;

outputting the small signal to an electrical input of the solenoid valve;

measuring, using a measurement unit, a response to the coupled small signal at the electrical input of the solenoid valve.

19. The method of claim 18, wherein generating the small signal comprises generating a periodic signal.

20. The method of claim 18, further comprising:

not coupling any small signal to the output during the time in which the power transistor drives current into the solenoid valve.

21. A method for controlling a solenoid valve, comprising:

determining a first impedance parameter based on an inductance of the solenoid valve

driving current, via a pre-driver controlling a control input of a power transistor, into the solenoid valve according to the first impedance parameter, wherein the current comprises a small signal;

measuring a response to the small signal of the driven current at the electrical input of the solenoid valve;

determining a second impedance parameter based on the measured response; and

comparing the first impedance parameter to the second impedance parameter.

22. The method of claim 21, wherein

if the measured impedance is not equal to the first impedance parameter, overwriting the first impedance parameter by second impedance parameter.

23. The method of claim 21, wherein the small signal comprises a small voltage signal.

24. The method of claim 21, wherein the small signal comprises a small current signal.

25. The method of claim 21, further comprising:

continuing to drive current into the solenoid valve according to the first impedance parameter after comparing the first impedance parameter to the second impedance parameter.

26. A computer-readable medium comprising instructions configured to cause a computing device to:

generate a small signal;

output the small signal to an electrical input of the solenoid valve;

measure, using a measurement unit, a response to the coupled small signal at the electrical input of the solenoid valve.