Method of Controlling a Motorized Window Treatment

• US 20080260363A1
• Filed: 04/04/2008
• Published: 10/23/2008
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Brenner, Thomas Warren, Lundy, Stephen, Carmen, Lawrence R.
• Granted Patent: US 7,839,109 B2
• Time in Patent Office: Days
• US Class Current: 388/811
• CPC Class Codes: E06B 9/68 Operating devices or mechanisms, e.g. with electric drive
• CPC Class Codes: H02P 7/04 by means of a H-bridge circuit
• CPC Class Codes: H02P 7/29 using pulse modulation

Abstract

A method of controlling a motorized window treatment provides for continued operation of the motorized window treatment during an overload or low-line condition. The motorized window treatment is driven by an electronic drive unit having a motor, a motor drive circuit, and a controller. The controller controls the motor drive circuit to drive the motor with a pulse-width modulated signal generated from a bus voltage. The controller is operable to monitor the magnitude of the bus voltage. If the bus voltage drops below a first voltage threshold, the controller stops the motor or reduces the duty cycle of the pulse-width modulated signal to allow the bus voltage to increase to an acceptable magnitude. When the bus voltage rises above a second voltage threshold, the controller begins driving the motor normally once again. During an overload or low-line condition, the controller is prevented from resetting, while driving the motor with minimal interruption to the movement of the motorized window treatment.

Claims

1. A method of controlling a motorized window treatment in response to a command, the motorized window treatment comprises a motor selectively driven by a bus voltage, the method comprising the steps of:

driving the motor in response to the command;

monitoring the magnitude of the bus voltage;

comparing the magnitude of the bus voltage to a first voltage threshold;

decreasing the amount of current supplied to the motor if the magnitude of the bus voltage has dropped below the first voltage threshold;

comparing the magnitude of the bus voltage to a second voltage threshold after the step of stopping driving the motor; and

increasing the amount of current supplied to the motor if the magnitude of the bus voltage has risen above the second voltage threshold.

2. The method of claim 1, wherein the step of decreasing the amount of current comprises stopping driving the motor if the magnitude of the bus voltage has dropped below the first voltage threshold, and the step of increasing the amount of current comprises driving the motor once again if the magnitude of the bus voltage has risen above the second voltage threshold.

3. The method of claim 2, further comprising the step of:

storing the command and a present position of the motorized window treatment in a memory if the magnitude of the bus voltage has dropped below the first voltage threshold.

4. The method of claim 3, further comprising the step of:

adjusting the present position of the motorized window treatment in response to the rotational position of the motor;

wherein the step of storing a present position further comprises storing a present position of the motorized window treatment in the memory each time the rotational position of the motor changes by the predetermined angle, such that a plurality of positions are stored in the memory.

5. The method of claim 4, further comprising the steps of:

incrementing a memory counter each time one of the plurality of positions is stored in the memory; and

storing the present value of the memory counter in the memory each time one of the plurality of position is stored in the memory, such that a plurality of memory counter values are stored in the memory.

6. The method of claim 3, further comprising the steps of:

recalling the command and the present position from the memory after the magnitude of the bus voltage has risen above the second voltage threshold; and

subsequently driving the motor in response to the command and the present position recalled from the memory.

7. The method of claim 1, wherein the step of driving the motor further comprises generating a pulse-width modulated signal characterized by a duty cycle, and driving the motor with the pulse-width modulated signal in response to the command.

8. The method of claim 7, wherein the step of decreasing the amount of current comprises decreasing the duty cycle of the pulse-width modulated signal driving the motor if the magnitude of the bus voltage has dropped below the first voltage threshold, and the step of increasing the amount of current comprises driving increasing the duty cycle of the pulse-width modulated signal if the magnitude of the bus voltage has risen above the second voltage threshold.

9. The method of claim 8, further comprising the step of:

storing the duty cycle of the pulse-width modulated signal in a memory before the step of decreasing the duty cycle of the pulse-width modulated signal;

wherein the step of increasing the duty cycle comprises increasing the duty cycle to the duty cycle stored in the memory.

10. The method of claim 9, further comprising the step of:

controlling the duty cycle in response to the magnitude of the bus voltage if the magnitude of the bus voltage has dropped below the first voltage threshold.

11. The method of claim 9, wherein the step of decreasing the duty cycle comprises decreasing the duty cycle to a predetermined duty cycle less than the duty cycle stored in the memory.

12. The method of claim 1, wherein the step of increasing the amount of current comprises increasing the amount of current supplied to the motor in response to the command if the magnitude of the bus voltage has risen above the second voltage threshold if the magnitude of the magnitude of the bus voltage has been greater than the second voltage threshold for more than a predetermined amount of time.

13. The method of claim 12, wherein the predetermined amount of time is approximately 50 msec.

14. The method of claim 1, wherein the second voltage threshold is greater than the first voltage threshold.

15. A method of operating a motor of a motorized window treatment in response to a command, the motorized window treatment comprises a motor selectively driven by a bus voltage, the method comprising the steps of:

driving the motor in response to the command;

monitoring the magnitude of the bus voltage;

comparing the magnitude of the bus voltage to a first voltage threshold;

stopping driving the motor if the magnitude of the bus voltage has dropped below the first voltage threshold;

comparing the magnitude of the bus voltage to a second voltage threshold after the step of stopping driving the motor; and

driving the motor once again in response to the command if the magnitude of the bus voltage has risen above the second voltage threshold.

16. A method of controlling a motorized window treatment in response to a command, the motorized window treatment comprises a motor selectively driven by a bus voltage, the method comprising the steps of:

generating a pulse-width modulated signal from the bus voltage, the pulse-width modulated signal characterized by a duty cycle;

driving the motor with the pulse-width modulated signal in response to the command;

monitoring the magnitude of the bus voltage;

comparing the magnitude of the bus voltage to a first voltage threshold; and

decreasing the duty cycle of the pulse-width modulated signal driving the motor if the magnitude of the bus voltage has dropped below the first voltage threshold.

17. The method of claim 16, further comprising the steps of:

comparing the magnitude of the bus voltage to a second voltage threshold after the step of reducing the duty cycle of the pulse-width modulated signal; and

increasing the duty cycle of the pulse-width modulated signal driving the motor if the magnitude of the bus voltage has risen above the second voltage threshold.

18. An electronic drive unit for controlling the position of a motorized window treatment comprising:

a motor coupled to the motorized window treatment for adjusting the position the motorized window treatment;

a motor drive circuit coupled to the motor for driving the motor from a bus voltage;

a controller coupled to the motor drive circuit operable to drive the motor drive circuit so as to control the rotation of the motor to control the motorized window treatment in response to a command; and

a bus voltage monitor circuit coupled to the controller for providing a control signal representative of a magnitude of the bus voltage to the controller;

wherein the controller is operable to compare the magnitude of the bus voltage to a first voltage threshold, to control the motor drive circuit to decrease the amount of current supplied to the motor if the bus voltage has dropped below the first voltage threshold, to subsequently compare the magnitude of the bus voltage to a second voltage threshold, and to control the motor drive circuit to increase the amount of current supplied to the motor if the bus voltage has risen above the second voltage threshold.

19. The electronic drive unit of claim 18, wherein the controller is operable to stop driving the motor if the magnitude of the bus voltage has dropped below the first voltage threshold, and to once again begin driving the motor if the bus voltage has risen above the second voltage threshold.

20. The electronic drive unit of claim 19, further comprising:

a rotational position sensor coupled to the motor, the controller operable to determine a rotational position of the motor in response to the rotational position sensor; and

a memory coupled to the controller, such that the controller is operable to store the command in the memory, the controller further operable to store a present position of the motorized window treatment in the memory in response to determining that the rotational position of the motor has changed by a predetermined angle;

wherein the controller is operable to recall the command and the present position from the memory after the controller is reset, and to drive the motor drive circuit in response to the command and the present position recalled from the memory.

21. The electronic drive unit of claim 18, wherein the controller is operable to generate a pulse-width modulated signal characterized by a duty cycle for driving the motor.

22. The electronic drive unit of claim 21, wherein the controller is operable to decrease the duty cycle of the pulse-width modulated signal if the magnitude of the bus voltage has dropped below the first voltage threshold, and to increase the duty cycle of the pulse-width modulated signal if the magnitude of the bus voltage has risen above the second voltage threshold.

23. The electronic drive unit of claim 18, further comprising:

a bus capacitor coupled to the drive circuit, the bus voltage produced across the bus capacitor; and

a rectifier for receiving a source voltage and for generating the bus voltage across the bus capacitor.

24. A system for delivering a transitory duration of high power from a power source to an electrical load without collapsing a supply voltage, the system comprising:

a first power supply for generating a bus voltage from a source voltage of the power source;

a second power supply for generating the supply voltage from the bus voltage;

a drive circuit receiving the bus voltage and adapted to control the amount of current delivered to the electrical load; and

a controller powered by the supply voltage and coupled to the drive circuit for controlling the amount of current delivered to the electrical load and responsive to the magnitude of the bus voltage, the controller operable to compare the magnitude of the bus voltage to a first voltage threshold, to control the drive circuit to decrease the amount of current supplied to the electrical load if the bus voltage has dropped below the first voltage threshold, to subsequently compare the magnitude of the bus voltage to a second voltage threshold, and to control the drive circuit to increase the amount of current supplied to the electrical load if the bus voltage has risen above the second voltage threshold.

25. The system of claim 24, wherein the first power supply comprises a bus capacitor and a rectifier for receiving a source voltage and for generating the bus voltage across the bus capacitor.