High-efficiency H-bridge circuit using switched and linear stages

• US 6,486,643 B2
• Filed: 08/27/2001
• Issued: 11/26/2002
• Est. Priority Date: 11/30/2000
• Status: Expired due to Term

• Current Assignee: Analog Technologies Incorporated
• Original Assignee: Analog Technologies Incorporated
• Inventors: Liu, Gang
• Primary Examiner(s): STERRETT, JEFFREY L
• Application Number:
  US09/813,078
• Publication Number:
  US 20020089316A1
• Time in Patent Office: 456 Days
• Field of Search: 323/268, 323/274, 323/284, 323/350
• US Class Current: 323/268
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• CPC Class Codes: H03F 1/02 Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence

Abstract

An H bridge regulating system for driving an electric load includes a linear output stage and switch mode output stage connected to opposite ends of the load. The linear output stage has a linear mode amplifier and a feedback circuit, and its amplifier generates a first output signal tied to one end of the load. This output voltage is passed through a conditioning resistor to an inverting input of the linear mode amplifier. The switch mode output stage has a switch mode amplifier and a feedback circuit, and its amplifier generates a second output signal tied to the other end of the load. Its voltage signal is passed through a second conditioning resistor to an inverting input of the switch mode amplifier. Other feedback circuit elements are also provided to create three distinct regions of operations for each of the amplifiers. Due to this novel arrangement for an H bridge circuit, and this novel method of operation involving three distinct regions of operation for the linear mode and switch mode output stages, very high power-saving energy efficiencies are achieved. In addition, H bridge systems for three terminal electrical devices such as three-phase electric motors are disclosed.

Claims

1. An H bridge regulating system for driving an electric load, the H bridge system comprising:

a linear output stage, the linear output stage having a linear mode amplifier with inverting and non-inverting inputs and a feedback circuit with a first element, the amplifier generating a first output signal, the first output signal passing through the first element of the feedback circuit to the inverting input of the linear mode amplifier;

a switch mode output stage, the switch mode output stage having a switch mode amplifier with inverting and non-inverting inputs and a feedback circuit with a first element, the switch mode amplifier generating a second output signal, the second output signal passing through the first element of the feedback circuit of the switch mode output stage to the inverting input of the switch mode amplifier, and wherein

the outputs of the linear mode amplifier and the switch mode amplifier are simultaneously connectable to an electric load to be driven.

2. The H bridge regulating system as in claim 1, further comprising an electric load including at least one thermoelectric cooler connected to the outputs of the linear mode amplifier and the switch mode amplifier.

3. The H bridge regulating system as in claim 1, further comprising:

an electric load being connected to the outputs of the linear mode amplifier and the switch mode amplifier, and wherein

the electric load is selected from the group of electric loads consisting of electric motors, coil motors, relay coils, solenoids, audio speakers, ultrasound transducers, horns, buzzers, and thermoelectric coolers.

4. The H bridge regulating system as in claim 1, wherein:

the feedback circuits of the linear mode output stage and the switch mode output stage each have at least a second element;

the second element of the linear mode output stage is in electrical communication with the inverting input of the linear mode amplifier; and

the second element of the switch mode output stage is in electrical communication with the non-inverting input of the switch mode amplifier.

5. The H bridge regulating system as in claim 4, further comprising an input to the H bridge system for receiving an input command signal, and wherein:

the feedback circuit of the switch mode output stage has at least third and fourth elements,

the third element of the switch mode output stage is in electrical communication with the inverting input of the switch mode amplifier and with the input for receiving the input command signal, and

the fourth element of the switch mode output stage is in electrical communication with the non-inverting input of the switch mode amplifier and the output of the linear mode amplifier.

6. The H bridge regulating system of claim 5, wherein the feedback circuit of the switch mode output stage is arranged to provide electrical communication between the output of the switch mode amplifier and the input command signal, and between the output of the linear mode amplifier and the non-inverting input of the switch mode amplifier.

7. The H bridge regulating system of claim 1, wherein the switch mode amplifier uses pulse width modulation.

8. The H bridge regulating system of claim 1, wherein the switch mode amplifier uses switch mode modulation.

9. The H bridge regulating system as in claim 1, further comprising:

a positive voltage supply and a negative voltage supply, with the linear mode amplifier and the switch mode amplifier each being connected to both the positive voltage supply and the negative voltage supply, and wherein

the linear mode output stage is arranged such that the linear mode amplifier is operable in one of three regions depending upon a desired load current magnitude and direction, the first region having the linear mode amplifier being at least substantially fully saturated to the negative voltage supply, and the second region having the linear mode amplifier being operated linearly throughout at least most of the region, and the third region having the linear mode amplifier being at least substantially fully saturated to the positive voltage supply.

10. The H bridge regulating system as in claim 9, wherein the linear mode output stage and the switch mode output stage are arranged such that:

a changing input signal to the non-inverting input of the linear mode amplifier results in the output signal from the switch mode amplifier changing in the opposite direction when the linear mode amplifier is in its first and third regions, and

a changing input signal to the non-inverting input of the linear mode amplifier results in the output signal from the switch mode amplifier changing in the same direction when the linear mode amplifier is in its second region.

11. The H bridge regulating system as in claim 9, wherein:

the gain of the linear mode amplifier is set such that the second region of the linear mode amplifier is sufficiently narrow to result in the linear mode amplifier having an efficiency greater than about eighty percent, whereby more than about 80 percent of the electrical power supplied to the linear mode amplifier is transferred to the electrical load.

12. The H bridge regulating system as in claim 1, further comprising:

an electric load connected to the outputs of the linear mode amplifier and the switch mode amplifier, and wherein

the electric load includes a thermoelectric cooler,

the feedback circuits of the linear mode output stage and the switch mode output stage each have at least a second element,

the second element of the linear mode output stage is in electrical communication with the inverting input of the linear mode amplifier; and

the second element of the switch mode output stage is in electrical communication with the non-inverting input of the switch mode amplifier.

13. The H bridge regulating system as in claim 12, wherein:

the feedback circuit of the switch mode output stage has at least third and fourth elements,

the third element of the switch mode output stage is in electrical communication with the non-inverting input of the linear mode amplifier and the output of the switch mode amplifier through the first element of the switch mode output stage; and

the fourth element of the switch mode output stage is in electrical communication with the non-inverting input of the switch mode amplifier and the output of the linear mode amplifier.

14. The H bridge regulating system as in claim 13, wherein all of the aforementioned elements of the feedback circuits of the linear mode output stage and the switch mode output stage are each substantially entirely resistive elements.

15. An electronic control system for driving an electric load having at least two terminals in a regulated manner, the control system including an H bridge arrangement for driving the electric load, the electronic control system comprising:

a linear mode amplifier having an input and having the output electrically connectable to the first terminal end of the electric load to be drive;

a switch mode amplifier having an input and having an output, the output being electrically connectable to the second terminal end of the electric load to be driven;

a load sensing circuit electrically connectable to the first and second terminal ends of the electric load to be driven, the load sensing circuit having at least one sensing output signal for providing information about at least one sensed electrical condition of the electric load;

an electronic processing circuit having first and second inputs and first and second outputs, the first input being for receiving a master input command signal, the second input being for receiving the sensing output signal of the load sensing circuit, the first and second outputs being for providing first and second input signals to the input of the linear mode amplifier and to the input of the switch mode amplifier respectively, and wherein the linear mode amplifier and switch mode amplifier are arranged in an H bridge configuration with the electric load being electrically connectable between the outputs of the linear mode amplifier and the switch mode amplifier, and

the electronic processing circuit is arranged to operate the linear mode amplifier in first, second and third regions of operation and the switch mode amplifier in first, second and third regions of operation, with the first and third regions of operation of the linear mode amplifier being regions in which at least a portion of the linear mode amplifier is at least substantially saturated, and with the second region of operation of the linear mode amplifier being a region in which the linear mode amplifier id operating linearly through a substantial portion of the second region.

16. The electronic control system of claim 15, wherein the linear mode amplifier has a closed-loop gain which is sufficient to provide a power efficiency for that amplifier of at least about 80 percent, whereby at least about 80 percent of the electrical power being supplied to the linear mode amplifier is passed therethrough to the electric load to be driven.

17. The electronic control system of claim 15, wherein the linear mode amplifier as arranged to have a closed-loop gain which is sufficient to provide a power efficiency for that amplifier of at least about 90 percent, whereby at least about 90 percent of the electrical power being supplied to the linear mode amplifier is passed therethrough to the electric load to be driven.

18. The electronic control system of claim 15, wherein the linear mode amplifier is arranged to have a closed-loop gain which is sufficient to provide a power efficiency for that amplifier of at least about 99 percent, whereby at least about 99 percent of the electrical power being supplied to the linear mode amplifier is passed therethrough to the electric load to be driven.

19. An electronic control system as in claim 18, further comprising the electric load to be driven, which load includes at least one thermoelectric cooler having first and second terminal ends connected to the outputs of the linear mode amplifier and the switch mode amplifier respectively.

20. The electronic control system of claim 15 wherein the switch mode amplifier is arranged such that, in its first and third regions, the output signal of the switch mode amplifier is proportional to the input command signal, and that in its second region, the output signal of the switch mode amplifier is proportional to the difference between the output signal of the linear mode amplifier and the input command signal.

21. The electronic control system of claim 15, further comprising:

an electric load having first and second terminal ends respectively connected to the outputs of the linear mode amplifier and the switch mode amplifier, the electric load being a thermoelectric cooler, and wherein the electronic processing circuit and the load sensing circuit are at least substantially comprised primarily of resistive elements.

22. The electronic control system of claim 15, further comprising an electric load having first and second terminal ends respectively connected to the outputs of the linear mode amplifier and the switch mode amplifier, the electric load being selected from the groups of electric loads consisting of electric motors, coil motors, relay coils, solenoids, audio speakers, ultrasound transducers, horns, buzzers, and thermoelectric coolers.

23. The electronic control system of claim 15, wherein the load sensing circuit senses a voltage across the load.

24. The electronic control system of claim 15, wherein the load sensing circuit senses a current flowing through the load.

25. The electronic control system of claim 15, wherein the load sensing circuit senses both a current flowing through the load and a voltage across the load.

26. The electronic control system of claim 15, wherein the load sensing circuit is arranged:

(a) to sense in real time both a current associated with the load and a first voltage associated with the load, whereby information as to the phase angle relationship of the load current and the first voltage associated with the load is obtained, and

(b) to pass along to the electronic processing unit at least periodically information as to the current and first voltage associated with the load, and as to the phase angle relationship therebetween.

27. The electronic control system of claim 15, wherein:

the load sensing circuit is arranged to produce a first sensed signal associated with the current of the load , and the provide the first and second sensed signals to the electronic processing circuit.

28. An electronic control system as in claim 15, further comprising the electric load to be driven, which load includes at least one thermoelectric cooler having first and second terminal ends connected to the outputs of the linear mode amplifier and the switch mode amplifier respectively.

29. The electronic control system of claim 15, wherein:

the system includes a positive voltage supply and a negative voltage supply, with the linear mode amplifier and the switch mode amplifier each being connected to both the positive voltage supply and the negative voltage supply, and

the linear mode amplifier is arranged such that, in its first region, the linear mode amplifier is at least substantially saturated to the negative voltage supply, and that in substantially all of its second region, the linear mode amplifier is operated linearly, and that in its third region, the linear mode amplifier is at least substantially saturated to the positive voltage supply.

30. An electronic control system as in claim 29, further comprising the electric load to be driven, which load includes at least one thermoelectric cooler having first and second terminal ends connected to the outputs of the linear mode amplifier and the switch mode amplifier respectively.

32. A method of driving an electric load using an H bridge system as in claim 28, wherein the second output signal in the second region of operation of the switch mode amplifier is proportional to a difference between a value associated with the first output signal and a value associated with the first input command signal.

33. A method of driving an electric load using an H bridge system as in claim 28, wherein the electric load is selected from the group of electrical loads consisting of electric motors, coil motors, relay coils, solenoids, audio speakers, ultrasound transducers, horns, buzzers, and thermoelectric coolers.

31. A method of driving an electric load, using an H bridge system, in proportion to a value of an input command signal, the method comprising the steps of:

(a) providing an H bridge system including first and second nodes for connecting an electric load to be driven thereto, the H bridge system having a linear mode amplifier and a switch mode amplifier, the linear mode amplifier being provided with an input and with an output which is connected to the first node, and the switch mode amplifier being provided with an input and with an output which is connected to the second node;

(b) connecting an electric load having two opposed terminal ends to the first and second nodes;

(c) providing an input command signal;

(d) communicating a first input signal related to the input command signal to the input of the linear mode amplifier;

(e) communicating a second input signal related to the input command signal to the input of the switch mode amplifier;

(f) generating a first output signal at the output of the linear mode amplifier in response to the first input signal;

(g) generating a second output signal at the output of the switch mode amplifier and

(h) simultaneously applying the first and second output signals to the first and second nodes to drive the electric load, such that the difference between the first and second output signals across the load is substantially proportional to the input command signal over at least a substantial portion of the full range of the input command signal.

34. A method of driving an electric load as in claim 31, wherein in step (g), the switch mode amplifier operates substantially linearly in first, second and third distinct regions which are respectively associated with but are different from the first, second and third regions of the linear mode amplifier.

35. A method of driving an electric load using an H bridge system as in claim 31, wherein, in step (f), the linear mode amplifier:

(1) operates in one of first, second and third regions, depending upon the value of the input command signal,

(2) operates in opposite saturation states when in the first and third regions, and

(3) operates substantially linearly in at least most of the second region, the second region being between the first and third regions, whereby the second region serves to smoothly transition the first output signal from a first saturation state associated with the first region to a second and opposite saturation state associated with the third region.

36. A method of driving an electric load using an H bridge system as in claim 35;

wherein;

the first region of the linear mode amplifier is characterized by the output signal thereof being substantially clamped at a fist supply voltage;

the third region of the linear mode amplifier is characterized by the output signal thereof being substantially clamped at a second supply voltage which is different from the first supply voltage; and

the second region of the linear mode amplifier is characterized by the first output signal being a function that is dependent upon the load current.

37. An electronic control system including a H bridge arrangement for driving an electric load having three terminal ends, each of which are to be driven, the electronic control system comprising:

a linear mode amplifier having an input and having an output electrically connectable to the first terminal en of the electric load to be driven;

a first switch mode amplifier having an input and having an output the output being electrically connectable to the second terminal end of the electric load to be driven;

a second switch mode amplifier having an input and having an output, the output being electrically connectable to the third terminal end of the electric load to be driven;

a load sensing circuit having at least one sensing output signal for providing information about at least one sensed electrical condition of the electric load;

an electronic processing circuit having at least first and second inputs and first, second and third output, the first input being for receiving a master input command signal, the second input being for receiving the sensing output signal of the load sensing circuit, the first, second and third outputs being for providing first, second and third input signals to the input of the linear mode amplifier and to the inputs of the first and second switch mode amplifiers respectively, and wherein

the linear mode amplifier and switch mode amplifiers are arranged in an H bridge configuration with the electric load being electrically connectable between the outputs of the linear mode amplifier and the first and second switch mode amplifiers, and

the electronic processing circuit is arranged to operate the linear mode amplifier in first, second and third regions of operation, the first switch mode amplifier in first, second and third regions of operation, and the second switch mode amplifier in first, second and third regions of operation, with the first and third regions of operation of the linear mode amplifier being regions in which at least a portion of the linear mode amplifier is at least substantially saturated, and with the second region of operation of the linear mode amplifier being a region in which the linear mode amplifier is operating linearly through a substantial portion of the second region.

38. The electronic control system of claim 37 wherein the first and second switch mode amplifiers are each arranged to be operable such that, in its first and third regions, the output signal of each switch mode amplifier is proportional to its input signal, and that in its second region, the output signal of each switch mode amplifier is proportional to the difference between the output signal of the linear mode amplifier and its input signal.

39. An electronic control system as in claim 37 wherein:

the load sensing circuit is electrically connectable to at least two of the first, second and third terminal ends of the electric load to be driven,

the load sensing circuit is arranged to generate at least first and second sensing output signals for providing information about at least first and second sensed electrical conditions of the electric load, and

the electronic processing circuit further has at least a third input for receiving the second sensing output signal of the load sensing circuit, and

the electronic processing circuit further has at least a third input for receiving the second sensing output signal of the load sensing circuit, and

the electronic processing circuit is arranged to utilize the first and second sensing output signals from the load sensing circuit to help control the operation of the linear mode amplifier and the first and second switch mode amplifiers.

40. The electronic control system of claim 37, wherein:

the system includes a first source for connecting to positive voltage supply and a second source for connecting a negative voltage supply, with the linear mode amplifier and the first and second switch mode amplifiers each being connected to both the first source and the second source, and

the linear mode amplifier is arranged to be operable such that, in its first region, the linear mode amplifier is at least substantially saturated to the negative voltage supply, and that in substantially all of its second region the linear mode amplifier is operated linearly, and that in its third region, the linear mode amplifier is at least substantially saturated to the positive voltage supply.

41. An electronic control system as in claim 37, further comprising the electric load which is a three-phase electrical device.

42. An electronic control system as in claim 41, wherein the three-phase electrical device is a three-phase electric motor.

43. An electronic control system including a H bridge arrangement for driving an electric load having three terminal ends, each of which are to be driven, the electronic control system comprising:

a first linear mode amplifier having an input and having an output, the output being electrically connectable to the first terminal end of the electric load to be driven;

a second linear mod amplifier having an input and having an output, the output being electrically connectable to the second terminal end of the electric load to be driven;

a switch mode amplifier having an input and having an output, the output being electrically connectable to the third terminal end of the electric load to be driven;

a load sensing circuit having at least one sensing output signal for providing information about at least one sensed electrical condition of the electric load;

an electronic processing circuit having at least first and second inputs and first, second and third outputs, the first input being for receiving a master input command signal, the second input being for receiving the sensing output signal of the load sensing circuit, the first, second and third outputs being for providing first, second and third input signals to the inputs of the first and second linear mode amplifiers and to the input of the switch mode amplifier respectively, and wherein

the linear mode amplifiers and the switch mode amplifier are arranged in an H bridge configuration with the electric load being electrically connectable between the outputs of the first and second linear mode amplifiers and the switch mode amplifier, and

the electronic processing circuit is arranged to operate the first and second linear mode amplifiers in first, second and third regions of operation, and the switch mode amplifier in first, second and third regions of operation, with the first and third regions of operation of the first and second linear mode amplifiers each being regions in which at least a portion of the respective linear mode amplifier is at least substantially saturated, and with the second region of operation of the respective linear mode amplifier being a region in which the linear mode amplifier is operating linearly through a substantial portion of the second region.

44. The electronic control system of claim 43 wherein the switch mode amplifier is arranged to be operable such that, in its first and third regions, the output signal of the switch mode amplifier is proportional to its input signal, and that in its second region, the output signal of the switch mode amplifier is proportional to the difference between the output signal of at least one of the linear mode amplifiers and the input signal to the switch mode amplifier.

45. An electronic control system as in claim 43 wherein:

the load sensing circuit is electrically connectable to at least two of the first, second and third terminal ends of the electric load to be driven,

the load sensing circuit is arranged to generate at least first and second sensing output signals for providing information about at least first and second sensed electrical conditions of the electric load, and

the electronic processing circuit further has at least a third input for receiving the second sensing output signal of the load sensing circuit, and

the electronic processing circuit is arranged to utilize the first and second sensing output signals from the load sensing circuit to help control the operation of the first and second linear mode amplifiers and the switch mode amplifier.

46. The electronic control system of claim 43, wherein:

the system includes a first source for connecting to positive voltage supply and a second source for connecting a negative voltage supply, with the first and second linear mode amplifiers and the switch mode amplifier each being connected to both the first source and the second source, and

the linear mode amplifiers are each arranged to be operable such that, in its respective first region, each linear mode amplifier is at least substantially saturated to the negative voltage supply, and that in substantially all of its respective second region, each linear mode amplifier is operated inearly, and that in its third respective region, each linear mod amplifier is at least substantially saturated to the positive voltage supply.

47. An electronic control system as in claim 43, further comprising the electric load which is a three-phase electrical device.

48. An electronic control system as in claim 43, wherein the three-phase electrical device is a three-phase electric motor.