Linear stage efficiency techniques for H-bridge systems

Patent metadata

Field	Value
Publication number	US-11194356-B2
Application number	US-202016886451-A
Country	US
Kind code	B2
Filing date	May 28, 2020
Priority date	Jun 28, 2019
Publication date	Dec 7, 2021
Grant date	Dec 7, 2021

Abstract

Techniques for efficient operation of a linear stage in an H-bridge system are provided. In an example, a linear stage can switch between voltage regulation and current regulation over a range of a command signal. The particular regulation mode can depend on the regulation mode of a switched stage of the H-bridge system. Efficiency can be realized by using current regulation of the linear stage when the output voltage of the linear stage moves away from the voltage of a supply rail. Such a control scheme can reduce the voltage across the linear stage for a larger range of the command signal resulting in less heat dissipation of the linear stage compared to conventional control of H-bridge linear stages.

First claim

What is claimed is:

1. A linear power stage for an H-bridge system, the H-bridge system configured to couple to a load and to include a switched power stage, the load configured to receive power via a differential voltage supplied by a first output of the linear power stage and a second output of the switched power stage, the linear power stage comprising:
a linear amplifier configured to receive power from a first supply rail and a second supply rail and to provide the first output; and
a control circuit configured to provide voltage regulation of the first output in response to the switched power stage providing current regulation of the second output, and to provide current regulation of the first output in response to the switched power stage providing voltage regulation of the second output.

2. The linear power stage of claim 1 , wherein the control circuit includes a first error amplifier configured to receive a representation of a voltage drop across the linear amplifier and a system command signal and to provide a first linear command signal to the linear amplifier.

3. The linear power stage of claim 2 , wherein an output of the first error amplifier is coupled to an input of the linear amplifier via a first diode.

4. The linear power stage of claim 2 , including a second error amplifier configured to receive a representation of a current supplied to the load and the system command signal and to provide a second linear command signal to the linear amplifier.

5. The linear power stage of claim 4 , including a third error amplifier configured to receive the representation of the current supplied to the load and the system command signal and having an output configured to couple with a first error signal of the switched power stage.

6. The linear power stage of claim 5 , wherein an output of the second error amplifier is configured to couple with a second error signal of the switched power stage.

7. The linear power stage of claim 6 , including a second diode configured to couple the first error signal with the output of the second error amplifier.

8. The linear power stage of claim 5 , including a second diode configured to couple the output of the third error amplifier with the first error signal.

9. The linear power stage of claim 8 , including a third diode configured to couple the output of the third error amplifier with the first linear command signal.

10. A system comprising:
a linear power stage comprising:
a power amplifier configured to provide a linear change in output voltage of the linear power stage in response to a change in a command signal; and
a power limit circuit configured to control the output voltage of the linear power stage to have a first slope characteristic with respect to the command signal in response to the output voltage of the switched stage being between a first threshold and a second threshold,
to control the output voltage of the linear power stage to have a second slope characteristic with respect to the command signal in response to the output voltage of the switched stage being at or above the first threshold, and
to control the output voltage of the linear power stage to have the second slope characteristic with respect to the command signal in response to the output voltage of the switched stage being at or below the second threshold,

wherein the first slope characteristic is greater than the second slope characteristic and the first threshold is greater than the second threshold.

11. The system of claim 10 , wherein the switched stage includes a first voltage-regulation error amplifier having an output coupled to an output of a first current-regulation error amplifier of the linear power stage.

12. The system of claim 11 , wherein the switched stage includes a second voltage-regulation error amplifier having an output coupled to an output of a second current-regulation error amplifier of the linear power stage.

13. The system of claim 12 , wherein a first input to the first voltage-regulation error amplifier is the first threshold, and a second input to the second voltage-regulation error amplifier is the second threshold.

14. The system of claim 10 , further comprising a switched power stage coupled to a first terminal of a load, the switched power stage configured to operate in a current regulation mode, and to establish a differential voltage across the load in response to the command signal;
wherein the linear power stage is coupled to a second terminal of the load.

15. A method of operating a H-bridge circuit, the method comprising:
for a first range of a command signal, operating a linear stage of the H-bridge circuit to provide an output voltage of the linear stage commensurate with a first supply voltage;
for the first range of the command signal, operating a switched stage of the H-Bridge circuit to provide a differential load voltage commensurate with the command signal;
for a second range of the command signal, operating the linear stage to provide the differential load voltage commensurate with the command signal; and
for the second range of the command signal, operating the switched stage to provide an output voltage of the switched stage commensurate with a voltage extreme of the switched stage.

16. The method of claim 15 , wherein, for the first range of the command signal, the operating the linear stage includes operating the linear stage in a voltage regulation mode to provide the output voltage of the linear stage commensurate with the first supply voltage.

17. The method of claim 15 , wherein, for the first range of the command signal, the operating the switched stage includes operating the switched stage in a current regulation mode to provide the differential load voltage commensurate with the command signal.

18. The method of claim 15 , wherein, for the second range of the command signal, the operating the linear stage includes operating the linear stage in a current regulation mode to provide the differential load voltage commensurate with the command signal.

19. The method of claim 15 , wherein, for the second range of the command signal, the operating the switched stage includes operating the switched stage in a voltage regulation mode responsive to the command signal.

20. The method of claim 19 , wherein operating the switched stage in a voltage regulation mode includes regulating the output voltage of the switched stage at an upper or lower voltage threshold the switched stage.

Assignees

• Analog Devices International Unlimited Co

Inventors

• Sun Fu
• Su Xiaohua
• Van Duyne Stephen Todd
• Lu Yanfeng
• Wich Mathew Todd

Classifications

• G05F1/618 Primary

  using semiconductor devices in series and in parallel with the load as final control devices (G05F1/461 takes precedence) · CPC title

• G05F1/56 Primary

  using semiconductor devices in series with the load as final control devices (G05F1/461 takes precedence) · CPC title

• G05F1/575

  characterised by the feedback circuit · CPC title

• Y02B70/10

  Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes · CPC title

• H02M1/0045

  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 title