Pilot signal generation circuit

• US 9,024,685 B2
• Filed: 12/03/2013
• Issued: 05/05/2015
• Est. Priority Date: 04/14/2010
• Status: Active Grant

• Current Assignee: Webasto Charging Systems, Inc. (Webasto Beteiligungs Verwaltung Gbr)
• Original Assignee: Aerovironment
• Inventors: Flack, Albert
• Primary Examiner(s): Nguyen, Khanh V
• Application Number:
  US14/095,945
• Publication Number:
  US 20140176236A1
• Time in Patent Office: 518 Days
• Field of Search: 330/10, 330/51, 330/69, 330/85, 330/109, 330/260
• US Class Current: 330/69
• CPC Class Codes: B60L 3/00 Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption methods or circuit arrangements for monitoring or controlling batteries or fuel cells B60L58/00
• CPC Class Codes: B60L 3/0069 relating to the isolation, e.g. ground fault or leak current
• CPC Class Codes: H02H 9/08 Limitation or suppression of earth fault currents, e.g. Petersen coil
• CPC Class Codes: H03F 1/3235 using a pilot signal
• CPC Class Codes: H03F 3/45 Differential amplifiers differential sense amplifiers G11C7/062

Abstract

In some embodiments, a pilot signal generation circuit is provided including a buffer and a differential amplifier responsive to an output of the buffer. A first transistor is connected to control a reference voltage at an input of the buffer in response to a pulse width modulated logic signal and a second transistor connected to control a reference voltage at an input of the differential amplifier based on the pulse width modulated logic signal such that the second transistor is connected so as to turn on when the first transistor is turned off and to turn off when the first transistor is turned on. The differential amplifier is configured to provide at an output a pilot signal proportional to a gain of the differential amplifier.

Claims

1. A pilot signal generation circuit comprising:

a) a buffer;

b) a differential amplifier responsive to an output of the buffer;

c) a first transistor connected to control a reference voltage at an input of the buffer in response to a pulse width modulated logic signal;

d) a second transistor connected to control a reference voltage at an input of the differential amplifier based on the pulse width modulated logic signal such that the second transistor is connected so as to turn on when the first transistor is turned off and to turn off when the first transistor is turned on; and

e) wherein the differential amplifier is configured to provide at an output a pilot signal proportional to a gain of the differential amplifier.

2. The pilot signal generation circuit of claim 1, wherein the second transistor is connected to an output of the first transistor so as to be responsive to the output of the first transistor to control the reference voltage at the input of the differential amplifier.

3. The pilot signal generation circuit of claim 2, wherein the first transistor and the second transistor are connected such that the reference voltage at the input of the differential amplifier is high when the reference voltage at the input of the buffer is low, and such that the reference voltage at the input of the differential amplifier is low when the reference voltage at the input of the buffer is high.

4. The pilot signal generation circuit of claim 1, wherein the first transistor and the second transistor are connected such that the reference voltage at the input of the differential amplifier is high when the reference voltage at the input of the buffer is low, and such that the reference voltage at the input of the differential amplifier is low when the reference voltage at the input of the buffer is high.

5. The pilot signal generation circuit of claim 1, wherein the reference voltage at the input of the buffer and the reference voltage at the input of the differential amplifier are connected via respective resistors to a common source reference voltage.

6. The pilot signal generation circuit of claim 5, wherein the second transistor is connected so as to respond to an output of the first transistor to control the reference voltage at the input of the differential amplifier based on the pulse width modulated logic signal.