Current controlled motor amplifier system

• US 6,683,437 B2
• Filed: 10/31/2001
• Issued: 01/27/2004
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: Immersion Corporation
• Original Assignee: Immersion Corporation
• Inventors: Tierling, Kollin
• Primary Examiner(s): Masih, Karen
• Application Number:
  US10/000,662
• Publication Number:
  US 20030080710A1
• Time in Patent Office: 818 Days
• Field of Search: 318/811, 318/594, 318/254, 318/280, 318/801, 318/800, 318/798, 388/829, 388/828, 388/811, 360/78.12
• US Class Current: 318/811
• 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 3/1555 for the generation of a regulated current to a load whose impedance is substantially inductive
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02P 7/04 by means of a H-bridge circuit
• CPC Class Codes: H02P 7/29 using pulse modulation
• CPC Class Codes: H02P 7/292 using static converters, e.g. AC to DC

Abstract

Aspects of a current controlled motor amplifier system are provided. These aspects include a current source motor amplifier comprising current source means on each leg of a top half of the H bridge configuration and switching means on each leg of a bottom half of the H bridge configuration. A motor is coupled to the current source motor amplifier at a center portion of the H bridge configuration. Control circuitry is coupled to the current source motor amplifier for controlling the switching on of the current source motor amplifier for a predetermined time to operate the top half of the H bridge configuration essentially as a linear constant current source and the bottom half of the H bridge configuration in switching mode. The aspects also allow for simplified circuitry to protect against overvoltage conditions and eliminate electrical damping in applications with higher rotational velocities associated with induced back EMF.

Claims

1. A method, comprising:

providing a substantially constant current source on each leg of a top half of an H bridge configuration;

providing a switch on a bottom half of each leg of the H bridge configuration;

switching on the substantially constant current source for a predetermined time and an appropriate switch to operate the top half of the H bridge configuration essentially as a linear substantially constant current source and the bottom half of the H bridge configuration in switching mode; and

achieving overvoltage protection in the current controlled motor amplifier by;

disabling the substantially constant current source on each leg;

enabling power transistors on each side of the H bridge configuration;

inducing a circulation current through a ground plane to limit back EMF induced motor voltage;

dissipating the back EMF induced motor voltage in a motor winding via the circulation current; and

including signal conditioning circuitry to control a duration of the overvoltage protection.

2. An apparatus, comprising:

a first current source coupled to a first terminal of an H-bridge amplifier configuration, the first current source being configured to operate substantially in a linear mode;

a second current source coupled to a second terminal of the H-bridge amplifier configuration, the second current source being configured to operate substantially in a linear mode;

a first switching component coupled to a third terminal of the H-bridge amplifier configuration, the first switching component being associated with the first current source, and the first switching component being configured to operate in a switching mode;

a second switching component coupled to a fourth terminal of the H-bridge amplifier configuration, the second switching component being associated with the second current source, and the second switching component being configured to operate in a switching mode; and

a control circuitry coupled to each of the first switching component and the second switching component, the control circuitry being configured to activate the first switching component and the second switching component during discrete time intervals, the first current source configured to provide a first directional current to a load coupled to the first current source and to the first switching component in response to activation from the control circuitry, and the second current source configured to provide a second directional current to a load coupled to the second current source and to the second switching component in response to activation from the control circuitry.

3. The apparatus of claim 2, wherein the first current source includes at least one transistor configured to provide current in a forward direction, and the second current source includes at least one transistor configured to provide current in a reverse direction.

4. The apparatus of claim 3, wherein each of the transistors of the first current source and the second current source includes a bipolar junction transistor.

5. The apparatus of claim 2, wherein each of the first switching component and the second switching component includes a field effect transistor.

6. The apparatus of claim 2, wherein the control circuitry includes a controller coupled to the H-bridge configuration, the control circuitry being configured to provide selection signals to the first current source and the second current source, and the first switching component and to the second switching component.

7. The apparatus of claim 6, wherein the control circuitry includes a multiplexer coupled to the controller and the H-bridge configuration, the controller and multiplexer collectively configured to provide selection signals to the first current source and the second current source, and to the first switching component and the second switching component.

8. The apparatus of claim 2, further comprising:

a forward-biased diode coupled to the first current source; and

a forward-biased diode coupled to the second current source.

9. The apparatus of claim 2, further comprising:

an overvoltage protection circuitry configured to induce a circulation current through a ground plane, and to dissipate back EMF experienced by a load.

10. An amplifier, comprising:

a first current source means coupled to a first terminal of an H-bridge amplifier configuration, the first current source means being configured to operate substantially in a linear mode;

a second current source means coupled to a second terminal of the H-bridge amplifier configuration, the second current source means being configured to operate substantially in a linear mode;

a first switching means coupled to a third terminal of the H-bridge configuration, the first switching means being associated with the first current source means, and the first switching means being configured to operate in a switching mode; and

a second switching means coupled to a fourth terminal of the H-bridge configuration, the second switching means being associated with the second current source means, and the second switching means being configured to operate in a switching mode.

11. The amplifier of claim 10, wherein the first current source means includes at least one transistor configured to provide a current in a forward direction, and the second current source means includes at least one transistor configured to provide current in a reverse direction.

12. The amplifier of claim 11, wherein each of the transistors of the first current source means and the second current source means includes a bipolar junction transistor.

13. The amplifier of claim 10, wherein each of the first switching means and the second switching means includes a field effect transistor.

14. The amplifier of claim 10, further comprising:

means for selectively activating each of the first switching means and the second switching means.

15. The amplifier of claim 14, wherein the means for selectively activating provides selection signals to each of the first current source means, the second current source means, the first switching means, and the second switching means to enable the first current source means and the second current source means to alternately provide respective currents in a forward direction and a reverse direction.

16. The amplifier of claim 10, further comprising:

a forward-biased diode coupled to the first current source means; and

a forward-biased diode coupled to the second current source means.

17. A method, comprising:

sourcing current to a first terminal of an H-bridge amplifier configuration, the current sourced to the first terminal being sourced in a linear mode;

sourcing current to a second terminal of the H-bridge amplifier configuration, the current sourced to the second terminal being sourced in a linear mode;

switching a state of a third terminal of the H-bridge amplifier configuration, the third terminal being associated with the first terminal;

switching a state of a fourth terminal of the H-bridge amplifier configuration, the fourth terminal being associated with the second terminal;

alternating the state of the third terminal and the state of the fourth terminal such that the third terminal and the fourth terminal are each activated during different time intervals;

providing the current sourced to the first terminal to a load in a first direction when the third terminal is activated; and

providing the current sourced to the second terminal to a load in a second direction when the fourth terminal is activated.

18. The method of claim 17 wherein the first terminal is located diagonally from the third terminal in the H-bridge configuration and wherein the second terminal is located diagonally from the fourth terminal in the H-bridge configuration.

19. The method of claim 17, wherein the providing current sourced to the first terminal to a load includes providing current from at least one transistor in a forward direction, and wherein the providing current sourced to the second terminal includes providing current from at least one transistor in a reverse direction.

20. The method of claim 19, wherein the providing current sourced to the first terminal includes providing current from at least one bipolar junction transistor, and wherein the providing current sourced to the second terminal includes providing current from at least one bipolar junction transistor.

21. The method of claim 17, wherein the switching the state of the third terminal includes activating a field effect transistor and the switching the state of the fourth terminal includes activating a field effect transistor.

22. The method of claim 17, further comprising:

protecting a load from an overvoltage condition by;

disabling the current sourced to the first terminal and the current sourced to the second terminal;

inducing a circulation current through a ground plane; and

dissipating any back EMF voltage via the induced circulation current.

23. The method of claim 22, further comprising:

controlling a duration of the protecting a load from an overvoltage condition according to control signals.

24. The method of claim 22, further comprising:

compensating for back EMF voltage.

25. The method of claim 24, wherein the compensating includes:

detecting a body diode conduction in a provided switch;

capacitively coupling a drive signal to the provided switch; and

prematurely terminating the drive signal to the provided switch on an opposite terminal of the H-bridge configuration.

26. The method of claim 17, further comprising:

regulating current provided by at least one-high power transistor independent of emitter-to-base voltage drops of the at least one-high power transistor.

27. Apparatus, comprising:

a first current source coupled to a first terminal of an H-bridge amplifier configuration, the first current source being configured to operate substantially in a linear mode;

a second current source coupled to a second terminal of the H-bridge amplifier configuration, the second current source being configured to operate substantially in a linear mode;

a first switch coupled to a third terminal of the H-bridge amplifier configuration, the first switch being associated with the first current source, the first switch being configured to operate in a switching mode; and

a second switch coupled to a fourth terminal of the H-bridge configuration, the second switch being associated with the second current source, the second switch being configured to operate in a switching mode.

28. The apparatus of claim 27, further comprising:

a control system configured to selectively activate a current source from the first current source and the second current source and to control which switch from the first switch and the second switch is activated.

29. The apparatus of claim 28, wherein the control system includes:

a controller and a multiplexer coupled to the H-bridge configuration, the controller and multiplexer being configured to collectively provide selection signals for each current source selected from the first current source and the second current source and each switch selected from the first switch and the second switch.