Detection of plunger movement in DC solenoids through current sense technique

Patent metadata

Field	Value
Publication number	US-10317453-B2
Application number	US-201816006880-A
Country	US
Kind code	B2
Filing date	Jun 13, 2018
Priority date	Nov 3, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

An apparatus and method of detecting movement of a plunger of the solenoid includes detecting a peak (IPEAK) in a current signal applied to a coil of the solenoid. A predetermined threshold is added to the current signal applied to the coil of the solenoid to generate a level shifted signal. The level shifted signal and the peak signal are compared to detect movement of a plunger of the solenoid.

First claim

The invention claimed is:

1. A method of detecting movement of a plunger of a solenoid comprising:
detecting a peak (I PEAK ) in a current signal applied to a coil of the solenoid;
detecting a valley in the current signal applied to the coil of the solenoid to generate a valley signal (I VALLEY );
adding a predetermined threshold to the current signal applied to the coil of the solenoid to generate a level shifted signal;
comparing the level shifted signal and the peak signal to detect movement of a plunger of the solenoid;
wherein the threshold is related to an absolute value of the difference between I PEAK and I VALLEY .

2. The method of claim 1 within the threshold is determined by measuring characteristics of the solenoid.

3. A method of detecting movement of a plunger of a solenoid comprising:
detecting a peak (I PEAK ) in a current signal applied to a coil of the solenoid;
detecting a valley in the current signal applied to the coil of the solenoid to generate a valley signal (I VALLEY );
adding a predetermined threshold to the current signal applied to the coil of the solenoid to generate a level shifted signal;
comparing the level shifted signal and the peak signal to detect movement of a plunger of the solenoid;
wherein if the current signal does not have a dip at least equal to the predetermined threshold, a fault signal is generated.

4. A method of detecting movement of a plunger of a solenoid comprising:
detecting a peak (I PEAK ) in a current signal applied to a coil of the solenoid;
detecting a valley in the current signal applied to the coil of the solenoid to generate a valley signal (I VALLEY );
adding a predetermined threshold to the current signal applied to the coil of the solenoid to generate a level shifted signal;
comparing the level shifted signal and the peak signal to detect movement of a plunger of the solenoid;
wherein if the current signal has a dip at least equal to the predetermined threshold, current to the solenoid is reduced to its hold value.

5. The method of claim 4 wherein the threshold is added to a voltage representing coil current which is compared with an output of an active peak detector, if the level shifted voltage matches the output of the active peak detector, complete solenoid movement has been detected.

6. The method of claim 3 wherein a dip less than the threshold indicates an unacceptably slower plunger movement.

7. In a system for operating a solenoid, a circuit to detect complete movement of a plunger of a solenoid, comprising:
a device for measuring current through the solenoid and generating a first current signal;
an active peak detector circuit receiving the first current signal for detecting a peak thereof and generating a peak detection signal;
a level shifter circuit coupled in parallel with the active peak detector and receiving the first current signal, the level shifter circuit adding a threshold voltage to the first current signal to generate a level shifted signal; and
a comparator comparing the peak detection signal with the level shifted signal, whereby if the level shifted signal matches the peak detection signal, complete movement of the solenoid is detected;
wherein the threshold is related to an absolute value of the difference between a current peak and a current valley.

8. In a system for operating a solenoid, a circuit to detect complete movement of a plunger of a solenoid, comprising:
a device for measuring current through the solenoid and generating a first current signal;
an active peak detector circuit receiving the first current signal for detecting a peak thereof and generating a peak detection signal;
a level shifter circuit coupled in parallel with the active peak detector and receiving the first current signal, the level shifter circuit adding a threshold voltage to the first current signal to generate a level shifted signal; and
a comparator comparing the peak detection signal with the level shifted signal, whereby if the level shifted signal matches the peak detection signal, complete movement of the solenoid is detected;
wherein the threshold is determined by measuring characteristics of the solenoid.

9. In a system for operating a solenoid, a circuit to detect complete movement of a plunger of the solenoid, comprising:
a device for measuring current through the solenoid and generating a first current signal;
an active peak detector circuit receiving the first current signal for detecting a peak thereof and generating a peak detection signal;
a level shifter circuit coupled in parallel with the active peak detector and receiving the first current signal, the level shifter circuit adding a threshold voltage to the first current signal to generate a level shifted signal; and
a comparator comparing the peak detection signal with the level shifted signal, whereby if the level shifted signal matches the peak detection signal, complete movement of the solenoid is detected;
wherein if the first current signal does not have a dip at least equal to the predetermined threshold, a fault signal is generated.

10. In a system for operating a solenoid, a circuit to detect complete movement of a plunger of the solenoid, comprising:
a device for measuring current through the solenoid and generating a first current signal;
an active peak detector circuit receiving the first current signal for detecting a peak thereof and generating a peak detection signal;
a level shifter circuit coupled in parallel with the active peak detector and receiving the first current signal, the level shifter circuit adding a threshold voltage to the first current signal to generate a level shifted signal; and
a comparator comparing the peak detection signal with the level shifted signal, whereby if the level shifted signal matches the peak detection signal, complete movement of the solenoid is detected;
wherein if the first current signal does not have a dip at least equal to the predetermined threshold, the solenoid current controller continues to drive the solenoid at its nominal current.

11. In a system for operating a solenoid, a circuit to detect complete movement of a plunger of the solenoid, comprising:
a device for measuring current through the solenoid and generating a first current signal;
an active peak detector circuit receiving the first current signal for detecting a peak thereof and generating a peak detection signal;
a level shifter circuit coupled in parallel with the active peak detector and receiving the first current signal, the level shifter circuit adding a threshold voltage to the first current signal to generate a level shifted signal; and
a comparator comparing the peak detection signal with the level shifted signal, whereby if the level shifted signal matches the peak detection signal, complete movement of the solenoid is detected;
wherein if the first current signal has a dip at least equal to the predetermined threshold, current to the solenoid is reduced to its hold value.

12. In a system for operating a solenoid, a circuit to detect complete movement of a plunger of the solenoid, comprising:
a device for measuring current through the solenoid and generating a first current signal;
an active peak detector circuit receiving the first current signal for detecting a peak thereof and generating a peak detection signal;
a level shifter circuit coupled in parallel with the active peak detector and receiving the first current signal, the level shifter circuit adding a threshold voltage to the first current signal to generate a level shifted signal; and
a comparator comparing the peak detection signal with the level shifted signal, whereby if the level s

Assignees

• Texas Instruments Inc

Inventors

• Narayanasamy Navaneeth Kumar
• Balakrishnan Manu

Classifications

• H01F7/1844

  Monitoring or fail-safe circuits (for relays H01H47/002) · CPC title

• H01F2007/185

  with armature position measurement · CPC title

• G01R31/2829

  Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844) · CPC title

• G01R31/06 Primary

  Physics · mapped topic

• G01D5/2006 Primary

  by influencing the self-induction of one or more coils (G01D5/22 takes precedence) · CPC title