Pilot signal generation circuit

• US 8,618,877 B2
• Filed: 10/14/2012
• Issued: 12/31/2013
• 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:
  US13/651,418
• Publication Number:
  US 20130187716A1
• Time in Patent Office: 443 Days
• Field of Search: 330/10, 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 various embodiments, a pilot signal generation circuit is provided having an operational amplifier buffer connected via a first resistor to receive a source reference voltage. A differential amplifier is connected at a first input to receive the source reference voltage and at a second input to an output of the operational amplifier buffer. A first shunt transistor is connected to shunt the source reference voltage at the operational amplifier buffer in response to pulse width modulated signal. A second shunt transistor is connected to the differential operational amplifier so as to shunt the source reference voltage in response to an output of the first shunt transistor. The output of the differential amplifier provides a pulse width modulated bipolar signal at precision voltage levels in response to the pulse width modulated signal.

Claims

1. A pilot signal generation circuit comprising:

a) a buffer connected to receive a source reference voltage;

b) a differential amplifier comprising a first input connected to receive the source reference voltage and a second input connected to an output of the buffer;

c) a first shunt transistor connected to shunt the source reference voltage at the buffer in response to a pulse width modulated signal;

d) a second shunt transistor connected to the differential amplifier so as to shunt the source reference voltage to the differential amplifier in response to an output of the first shunt transistor; and

e) wherein the output of the differential amplifier provides a pulse width modulated bipolar signal at precision voltage levels in response to the pulse width modulated signal.

2. The circuit of claim 1, wherein the buffer comprises an operational amplifier.

3. The circuit of claim 2, wherein the operational amplifier is connected via a first resistor to receive the source reference voltage, and wherein the differential amplifier is connected via a second resistor to receive the source reference voltage.

4. The circuit of claim 2, wherein the pilot signal generation circuit is configured to receive a logic level pulse width modulated signal at the input of the first shunt transistor.

5. The circuit of claim 2, further comprising a processor connected to an input of the first shunt transistor.

6. The circuit of claim 2, wherein the first shunt transistor and the second shunt transistor comprise field effect transistors.

7. The circuit of claim 1, wherein the differential amplifier is capable of providing a pulse width modulated bipolar output signal within about 1% at +/−

12 Volts in response to a logic level source reference voltage.

8. A pilot signal generation circuit comprising:

a) a first operational amplifier comprising a first input connected via a first resistor to receive a source reference voltage, the first operational amplifier being configured to buffer the first input to an output of the first operation amplifier;

b) a second operational amplifier configured as a differential amplifier comprising a first input connected via a second resistor to receive the source reference voltage and a second input connected via a third resistor to the output of the first operational amplifier;

c) a first transistor connected to the first operational amplifier to be capable of shunting the source reference voltage at the input of the first operational amplifier;

d) a second transistor connected to the second operational amplifier so as to be capable of shunting the source reference voltage at the first input of the second operational amplifier in response to a voltage level at the first input of the first operation amplifier; and

e) wherein pilot signal generation circuit is configured to receive a pulse width modulated signal at an input of the first transistor and to provide a precision voltage pulse width modulated bipolar signal at the output of the second operational amplifier.

9. The circuit of claim 8, wherein the pilot signal generation circuit is configured to receive a logic level pulse width modulated signal at the input of the first transistor.

10. The circuit of claim 8 further comprising a processor connected to the gate of the first transistor.

11. The circuit of claim 8, wherein the first shunt transistor and the second shunt transistor comprise field effect transistors.

12. The circuit of claim 8, wherein the second operational amplifier is capable of providing a pulse width modulated bipolar output signal within about 1% at +/−

12 Volts in response to a logic level source reference voltage.

13. A pilot signal generation circuit comprising:

a) a first operational amplifier comprising;

i) a non-inverting input connected via a first resistor to receive a source reference voltage;

ii) an inverting input; and

iii) an output directly connected to the inverting input of the first operational amplifier;

b) a second operational amplifier comprising;

i) a non-inverting input connected via a second resistor to receive the source reference voltage and also connected in parallel to ground via a third resistor;

ii) an inverting input connected via a fourth resistor to the output of the first operational amplifier; and

iii) an output connected via a fifth resistor to the inverting input of the second operational amplifier;

c) a first transistor comprising;

i) a gate connected to receive a logic level pulse width modulated control signal;

ii) a drain connected to the non-inverting input of the first operational amplifier; and

iii) a source connected to ground; and

d) a second transistor comprising;

i) a gate connected to the drain of the first transistor;

ii) a drain connected to the non-inverting input of the second operational amplifier; and

iii) a source connected to ground.

14. The circuit of claim 13, further comprising a microprocessor connected to the gate of the first transistor.

15. The circuit of claim 13, wherein the first transistor and the second transistor comprise field effect transistors.

16. The circuit of claim 13, wherein the second operational amplifier is capable of providing a bipolar pulse width modulated output signal within about 1% at +/−

12 Volts in response to the logic level pulse width modulated control signal at the non-inverting input of the first operational amplifier.