Voltage sensing with high and low side signals for deadtime compensation and shutdown for short circuit protection

• US 6,580,627 B2
• Filed: 11/30/2001
• Issued: 06/17/2003
• Est. Priority Date: 01/29/2001
• Status: Expired due to Term

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Toshio, Takahashi
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US09/996,975
• Publication Number:
  US 20020105316A1
• Time in Patent Office: 564 Days
• Field of Search: 363/16, 363/17, 363/97, 363/98, 363/131, 363/132
• US Class Current: 363/98
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/385 with means for correcting output voltage deviations introduced by the dead time
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H03K 17/0828 in composite switches

Abstract

A circuit for sensing the voltage across a power device, such as an insulated gate bipolar transistor (IGBT), that provides a power signal, such as to a motor. Where power devices are connected in a half bridge configuration, the sensing circuitry provides low side and high side sense signals. The signals indicate respectively when voltage changes across the low side and high side power devices. If on times of the devices are separated by deadtime, one sense signal can indicate the beginning of deadtime and the other can indicate the ending of the deadtime. The sensing circuitry can provide a sense result signal indicating whether voltage across the power device is greater than a reference voltage. The sense result signal can be received both by feedback signal circuitry that provides a signal indicating when voltage changes and also by shutdown circuitry that causes driving circuitry to turn off the power device if it is turned on when voltage across it is greater than the reference voltage, which occurs in a short circuit condition. The circuitry can be combined in an integrated circuit in which low side and high side sense signals are used both to provide voltage feedback signals and also to turn off the low or high side device if it is on when the voltage across it exceeds its reference voltage.

Claims

1. A voltage feedback circuit for low side and high side power devices arranged in a half-bridge configuration for providing an output power signal, the output power signal depending on voltages across the low and high side power devices, the voltage feedback circuit comprising:

sensing circuitry that senses voltage changes across the low and high side power devices;

the sensing circuitry providing low and high side sense signals, the low side sense signal indicating when voltage changes across the low side power device and the high side sense signal indicating when voltage changes across the high side power device.

2. The circuit of claim 1 in which the low and high side power devices are separately turned on and off to control the voltages thereacross, wherein on times of the low and high side power devices are separated by a deadtime that begins when one of the devices is turned off and ends when the other is turned on, and wherein one of the low and high side sense signals indicates a beginning of the deadtime and the other indicates an ending of the deadtime.

3. An integrated circuit that includes the voltage feedback circuit of claim 1, wherein the sensing circuitry includes:

low side sensing circuitry for providing the low side sense signal; and

high side sensing circuitry for providing the high side sense signal;

the low and high side sensing circuitry including low and high side sense input pins, respectively, for receiving sense input signals from the low and high side power devices, respectively, each sense input signal including information about voltage across the respective power device.

4. An integrated circuit that includes a voltage feedback circuit for low side and high side power devices arranged in a half-bridge configuration for providing an output power signal, the output power signal depending on voltages across the low and high side power devices, the voltage feedback circuit comprising:

sensing circuitry that senses voltage changes across the low and high side power devices;

the sensing circuitry providing low and high side sense signals, the low side sense signal indicating when voltage changes across the low side power device and the high side sense signal indicating when voltage changes across the high side power device;

wherein the sensing circuitry includes;

low side sensing circuitry for providing the low side sense signal; and

high side sensing circuitry for providing the high side sense signal;

the low and high side sensing circuitry including low and high side sense input pins, respectively, for receiving sense input signals from the low and high side power devices, respectively, each sense input signal including information about voltage across the respective power device;

wherein each of the power devices has a respective power supply lead and a respective ground lead, the sense input signal for each power device indicating voltage at the respective power supply lead,

each of the low and high side sensing circuitry including a respective comparator with first and second inputs, the first input for receiving the respective sense input signal and the second input for receiving a reference voltage relative to the respective round lead, the comparator providing a result signal indicating whether the sense input signal is greater than the reference voltage, the result signal including a transition between low and high values when voltage changes across the respective power device.

5. The integrated circuit of claim 4 wherein each of the low and high side power devices has a respective gate lead for receiving signals to turn the device on and off, the integrated circuit further including:

low and high side driving circuitry for the low and high side power devices, respectively, each of the low and high side driving circuitry including a respective driver for providing an output drive signal in response to a respective input drive signal indicating whether to turn on or off the respective device and a driver output pin for connecting to provide the output drive signal to the respective power device'"'"'s gate lead; and

low and high side shutdown circuitry, each causing the respective low or high side driver to turn off the respective power device if the power device is turned on when the result signal from the respective comparator indicates that the sense input signal is greater than the reference voltage.

6. The integrated circuit of claim 5 wherein each input drive signal is derived from a pulse width modulated drive signal, each of the low and high side driving circuitry including a respective driver input pin for connecting to receive the respective input drive signal, the high side driving circuitry further including level shift up circuitry that shifts the high side input drive signal to a high side voltage range.

7. A power control circuit that includes a voltage feedback circuit for low side and high side power devices arranged in a half-bridge configuration for providing an output power signal, the output power signal depending on voltages across the low and high side power devices, the voltage feedback circuit comprising:

sensing circuitry that senses voltage changes across the low and high side power devices;

the sensing circuitry providing low and high side sense signals, the low side sense signal indicating when voltage changes across the low side power device and the high side sense signal indicating when voltage changes across the high side power device;

each of the low and high side power devices having a respective gate lead for receiving signals to turn the device on and off, each of the low and high side sense signals indicating whether voltage across the respective power device is greater than a reference voltage;

the power control circuit further including;

low and high side driving circuitry for the low and high side power devices, respectively, each of the low and high side driving circuitry being connected to provide a respective output drive signal to the respective power device gate lead; and

low and high side shutdown circuitry, each causing the respective low or high side driver to turn off the respective power device if the power device is turned on when the respective low or high side sense signal indicates that voltage across the respective power device is greater than the reference voltage.

8. The power control circuit of claim 7 wherein each of the low and high side driving circuitry includes a respective driver that provides the output drive signal in response to a respective input drive signal indicating whether to turn on or off the respective power device, each of the low and high side shutdown circuitry receiving the respective low or high side sense signal from the respective sensing circuitry and the respective input drive signal and, if the sense signal and the input drive signal indicate that the respective power device is turned on when the voltage across the respective power device is greater than the reference voltage, causing the respective driver to turn off the respective power device.

9. A voltage feedback circuit for low side and high side power devices arranged in a half-bridge configuration for providing an output power signal, the output power signal depending on voltages across the low and high side power devices, the voltage feedback circuit comprising:

sensing circuitry that senses voltage changes across the low and high side power devices;

the sensing circuitry providing low and high side sense signals, the low side sense signal indicating when voltage changes across the low side power device and the high side sense signal indicating when voltage changes across the high side power device; and

feedback signal circuitry for receiving the low and high side sense signals and, in response, providing first and second feedback signals obtained respectively from the low and high side sense signals, the feedback signal circuitry including level shilling circuitry that shills at least one of the high and low side sense signals to obtain the first and second feedback signals in approximately the same voltage range.

10. The circuit of claim 9 in which the level shifting circuitry shifts only the high side sense signal to obtain the second feedback signal.

11. An integrated circuit that includes the voltage feedback circuit of claim 9, the feedback signal circuitry including low and high side feedback output pins for connecting to provide the first and second feedback signals.

12. A power control circuit for controlling a power device that provides an output power signal, the output power signal depending on voltage across the power device, the power device having a gate lead for receiving signals to turn the power device on and off, the power control circuit comprising:

driving circuitry that provides output drive signals to the power device'"'"'s gate lead;

sensing circuitry for providing a sense result signal indicating whether voltage across the power device is greater than a reference voltage;

feedback signal circuitry for receiving the sense result signal and, in response, providing a voltage feedback signal indicating when voltage changes across the power device; and

shutdown circuitry for receiving the sense result signal and causing the driving circuitry to turn off the power device if the power device is turned on when the sense result signal indicates that voltage across the power device is greater than the reference voltage.

13. An integrated circuit that includes the power control circuit of claim 12, the power device having a power supply lead and a ground lead, the sensing circuitry including:

a sense input pin for receiving a sense input signal indicating voltage at the power supply lead; and

a comparator with first and second inputs, the first input receiving the sense input signal from the sense input pin and the second input receiving the reference voltage relative to the ground lead, the comparator providing the sense result signal.

14. The integrated circuit of claim 13 wherein the driving circuitry includes:

a driver for providing the output drive signals in response to the shutdown circuitry and in response to an input drive signal indicating whether to turn on or off the power device, the driver providing the output drive signals in accordance with the input drive signal except when the shutdown circuitry causes the driver to turn off the power device; and

a driver output pin for connecting to provide the output drive signals to the gate lead.

15. A power control circuit for low and high side power devices that provide an output power signal, the output power signal depending on voltages across the low and high side power devices, each of the power devices having a respective gate lead for receiving signals to turn the power device on and off, the power control circuit comprising:

driving circuitry for providing low and high side output drive signals for the gate leads of the low and high side power devices, respectively;

sensing circuitry for sensing voltage changes across the low and high side power devices, the sensing circuitry providing low and high side sense signals indicating respectively whether voltage across the low or high side power device is greater than a respective reference voltage;

feedback signal circuitry for receiving the low and high side sense signals and, in response, providing voltage feedback signals indicating when voltages change across the low and high side power devices; and

shutdown circuitry for receiving the low and high side sense signals and causing the driving circuitry to turn off the low or high side power device if the power device is turned on when the respective sense result signal indicates that voltage across the power device is greater than the respective reference voltage.

16. The circuit of claim 15 wherein the low and high side power devices can be separately turned on and off to control the voltages across them, on times of the low and high side power devices being separated by a deadtime that begins when one of the devices is turned off and ends when the other is turned on;

one of the low and high side sense signals indicating a beginning of the deadtime and the other indicating an ending of the deadtime;

the voltage feedback signals indicating the beginning and ending of the deadtime.

17. The circuit of claim 15 wherein the driving circuitry includes low and high side driving circuitry for the low and high side power devices, respectively, each of the low and high side driving circuitry providing the respective output drive signal to the respective power device'"'"'s gate lead;

each of the low and high side driving circuitry including;

a respective driver for providing the respective output drive signal in response to the shutdown circuitry and in response to a respective input drive signal indicating whether to turn on or off the respective power device, the driver providing the respective output drive signal in accordance with the respective input drive signal except when the shutdown circuitry causes the driver to turn off the power device.

18. An integrated circuit that includes the power control circuit of claim 15, the sensing circuitry including:

low side sensing circuitry that provides the low side sense signal; and

high side sensing circuitry that provides the high side sense signal;

the low and high side sensing circuitry including low and high side sense input pins, respectively, for receiving sense input signals from the low and high side power devices, respectively, each sense input signal including information about voltage across the respective power device.

19. An integrated circuit that includes the power control circuit of claim 15, the feedback signal circuitry including low and high side feedback output pins for connecting to provide low and high side voltage feedback signals, respectively indicating when voltage across the respective power device changes between less than and greater than the respective reference voltage.

20. The circuit of claim 15 wherein the voltage feedback signals include first and second feedback signals obtained respectively from the low and high side sense signals, the feedback signal circuitry including level shifting circuitry that shifts at least one of the high and low side sense signals to obtain the first and second feedback signals in approximately the same voltage range.