Treadmill motor control

• US 6,443,875 B1
• Filed: 08/30/2000
• Issued: 09/03/2002
• Est. Priority Date: 09/07/1999
• Status: Expired due to Term

• Current Assignee: Life Fitness LLC
• Original Assignee: Brunswick Corporation
• Inventors: Kim, Young-Chul, Sutkowski, Robert J., Lantz, Kenneth F., Golen, Emil S. Jr.
• Primary Examiner(s): Richman, Glenn E.
• Application Number:
  US09/651,248
• Time in Patent Office: 734 Days
• Field of Search: 482/51, 482/54
• US Class Current: 482/54
• CPC Class Codes: A63B 2024/0009 Computerised real time comparison with previous movements or motion sequences of the user
• CPC Class Codes: A63B 2024/0078 Exercise efforts programmed as a function of time
• CPC Class Codes: A63B 2024/0093 the load of the exercise apparatus being controlled by performance parameters, e.g. distance or speed
• CPC Class Codes: A63B 22/02 with movable endless bands , e.g. treadmills other training appliances for running on the spot A63B69/0028
• CPC Class Codes: A63B 22/0207 having shock absorbing means
• CPC Class Codes: A63B 22/0242 with speed variation
• CPC Class Codes: A63B 22/025 electrically, e.g. D.C. motors with variable speed control
• CPC Class Codes: A63B 2220/13 Relative positions
• CPC Class Codes: A63B 24/0006 Computerised comparison for qualitative assessment of motion sequences or the course of a movement
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 7/53873 with digital control
• CPC Class Codes: Y02B 70/10 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

Abstract

A motor control for exercise treadmill having an AC motor is disclosed which includes various features to enhance operation of the treadmill. These features include a motor control that can vary by shifting or staggering the phases of drive signals applied to the motor in order to reduce treadmill frame vibration. The features also include having the motor controller increase the slip of the motor to improve low speed operation of the motor and to increase the amperage of the drive signals when the motor is operating at a given speed in order to maintain that speed. In addition, a power factor control circuit can be used to increase the efficiency of the motor.

Claims

1. An exercise treadmill, comprising:

a frame structure including two rotatable pulleys, said pulleys being positioned substantially parallel to each other, and a pair of spaced apart longitudinal frame members for providing longitudinal structural support for said frame structure wherein said frame structure has a frame resonance frequency;

a three phase AC motor, having a plurality of armature windings, operatively connected to a first of said pulleys for rotating said first pulley;

a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

a control system operatively connected to said motor;

a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a first set of user controls for controlling the treadmill including said belt speed; and

a motor controller, operatively connected to said control system, having a processor and a plurality of drive transistors operatively connected to said processor to apply drive signals, having varying amplitude and frequency with predetermined phases, to each of said armature windings wherein said processor applies a control signal to said drive transistors such that the phases of said drive signals are shifted a predetermined amount from said predetermined phases at the speed of said motor corresponding to said frame resonance frequency.

2. The exercise treadmill of claim 1 wherein said phase shifting occurs at zero crossings of said drive signals.

3. The exercise treadmill of claim 1 wherein said processor increases said phase shifting from a minimum speed of said motor to said predetermined amount at said motor speed corresponding to said frame resonance frequency and then decreases said phase shifting as said speed of said motor increases beyond said resonant frequency.

4. The exercise treadmill of claim 3 wherein said increase and decrease of said phase shifting are linear with respect to increases in the speed of said motor.

5. The exercise treadmill of claim 1 wherein said predetermined amount is approximately 2 percent.

6. An exercise treadmill, comprising:

a frame structure including two rotatable pulleys, said pulleys being positioned substantially parallel to each other, and a pair of spaced apart longitudinal frame members for providing longitudinal structural support for said frame structure wherein said frame structure has a frame resonance frequency;

a three phase AC motor, having a plurality of armature windings, operatively connected to a first of said pulleys for rotating said first pulley;

a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

a control system operatively connected to said motor;

a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a first set of user controls for controlling the treadmill including said belt speed; and

a motor controller, operatively connected to said control system, having a processor and a plurality of drive transistors operatively connected to said processor to apply drive signals, having varying amplitude and frequency with predetermined phases, to each of said armature windings wherein said processor applies a control signal to said drive transistors such that at least one of said phases of said drive signals are staggered a predetermined amount from said predetermined phases at the speed of said motor corresponding to said frame resonance frequency.

7. The exercise treadmill of claim 6 wherein said predetermined amount of said phase staggering is approximately zero for a first of said phases, a minus 5 degrees for a second of said phases and a plus 5 degrees for a third of said phases.

8. An exercise treadmill, comprising:

a frame structure including two rotatable pulleys, said pulleys being positioned substantially parallel to each other, and a pair of spaced apart longitudinal frame members for providing longitudinal structural support for said frame structure wherein said frame structure has a frame resonance frequency;

a three phase AC motor, having a plurality of armature windings, operatively connected to a first of said pulleys for rotating said first pulley;

a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

a control system operatively connected to said motor;

a motor speed sensor operatively connected to said motor and said control system;

a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a first set of user controls for controlling the treadmill including said belt speed; and

a motor controller, operatively connected to said control system, having a processor and a plurality of drive transistors operatively connected to said processor to apply drive signals, having varying amplitude and frequency to each of said armature windings wherein said processor responsive to said motor speed sensor applies at low motor speed a control signal to said drive transistors such that the frequency of said drive signals is substantially greater than the speed of the motor to generate a substantial slip in said motor.

9. The exercise treadmill of claim 8 wherein said processor also reduces the amplitude of said drive signal during said slip of said motor in order to regulate the speed of said belt.

10. An exercise treadmill, comprising:

a frame structure including two rotatable pulleys, said pulleys being positioned substantially parallel to each other, and a pair of spaced apart longitudinal frame members for providing longitudinal structural support for said frame structure wherein said frame structure has a frame resonance frequency;

a three phase AC motor, having a plurality of armature windings, operatively connected to a first of said pulleys for rotating said first pulley;

a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

a control system operatively connected to said motor;

a motor speed sensor operatively connected to said motor and said control system;

a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a first set of user controls for controlling the treadmill including a plurality of predetermined speeds of said belt; and

a motor controller, operatively connected to said control system, having a processor and a plurality of drive transistors operatively connected to said processor to apply drive signals, having varying amplitude and frequency, to each of said armature windings wherein said processor, responsive to said user controls and said motor speed sensor, applies a motor speed control signal, representing a first of said predetermined belt speeds, to said drive transistors such that said drive transistors apply a first set of voltages and frequencies to said armature windings to obtain said first belt speed and wherein if said first belt speed should decrease due to increased load on said belt as indicated by said motor speed sensor, said processor will increase said voltage applied by said drive transistors to said armature windings to maintain the belt speed at said first belt speed.

11. An exercise treadmill that utilizes a power source, comprising:

a frame structure including two rotatable pulleys, said pulleys being positioned substantially parallel to each other, and a pair of spaced apart longitudinal frame members for providing longitudinal structural support for said frame structure wherein said frame structure has a frame resonance frequency;

a three phase AC motor, having a plurality of armature windings, operatively connected to a first of said pulleys for rotating said first pulley;

a belt secured over said pulleys so as to move in a longitudinal direction when said first pulley is rotated;

a control system operatively connected to said motor;

a motor speed sensor operatively connected to said motor and said control system;

a control panel secured to said frame structure and operatively connected to said control system wherein said control panel includes at least one display and a first set of user controls for controlling the treadmill including a plurality of predetermined speeds of said belt;

a motor controller, operatively connected to said control system to apply drive signals, having varying amplitude and frequency to each of said armature windings; and

a power factor control circuit, operatively connected between the power source and said motor control, for improving the power factor of the current applied to said motor controller from the power source.

12. The exercise treadmill of claim 11 including a rectifier connected between the power source and said power factor control circuit wherein said power factor control circuit includes an inductor and a switch connected to a line from the power source and operatively connected to a power factor controller.

13. The exercise treadmill of claim 12 wherein said switch is a power transistor.