METHOD FOR CONTROLLING OPERATION OF AN ELECTRIC MOTOR IN A HEIGHT-ADJUSTABLE FURNITURE ARRANGEMENT

• US 20120181968A1
• Filed: 01/19/2012
• Published: 07/19/2012
• Est. Priority Date: 01/19/2011
• Status: Active Grant

• Current Assignee: Rol AB
• Original Assignee: Kih-Utveckling AB
• Inventors: Clausen, Björn, Pettersson, Hans
• Granted Patent: US 9,608,557 B2
• Time in Patent Office: Days
• US Class Current: 318/504
• CPC Class Codes: A47B 9/00 Tables with tops of variable height lecterns with variable height A47B19/06; school forms or desks with variable height A47B39/02, A47B41/02; seats with variable height A47C3/20
• CPC Class Codes: H02P 2205/03 Power loop, i.e. comparison of the motor power with a power reference
• CPC Class Codes: H02P 29/40 Regulating or controlling the amount of current drawn or delivered by the motor for controlling the mechanical load

Abstract

The present invention relates to a method for controlling operation of an electric motor in a height-adjustable furniture arrangement, wherein operation of the electric motor provides a height-adjusting function in the height-adjustable furniture arrangement. The method comprises the steps of providing, by a power supply unit connected to the electric motor, an incoming power comprising an incoming current and an incoming voltage, transforming the incoming current and the incoming voltage to a motor supply current and a motor supply voltage supplied to the electric motor, measuring load on the electric motor, and when the measured load requires a current higher than the incoming current for providing the height-adjusting function, setting the levels of the motor supply current and/or the motor supply voltage such that the motor supply current is higher than the incoming current and the motor supply voltage is lower than the incoming voltage.

Claims

1. Method for controlling operation of an electric motor in a height-adjustable furniture arrangement, wherein operation of the electric motor provides a height-adjusting function in the height-adjustable furniture arrangement, the method comprising;

providing, by a power supply unit connected to the electric motor, an incoming power comprising an incoming current and an incoming voltage;

transforming the incoming current and the incoming voltage to a motor supply current and a motor supply voltage supplied to the electric motor,

measuring load on the electric motor, and

when the measured load requires a motor supply current higher than the incoming current for providing the height-adjusting function, setting the levels of the motor supply current and/or the motor supply voltage such that the motor supply current is higher than the incoming current and the motor supply voltage is lower than the incoming voltage.

2. Method according to claim 1, wherein measuring the load on the electric motor is realized by measuring the motor supply current level that the motor demands for providing the height-adjusting function, and wherein the setting is realized by calculating a motor supply voltage level necessary for achieving the measured motor supply current level and setting the motor supply voltage to the calculated motor supply voltage level.

3. Method according to claim 2, wherein setting the motor supply voltage comprises comparing the calculated motor supply voltage level to a predetermined minimum motor supply voltage level, and only setting the motor supply voltage to the calculated level if the calculated level is above the predetermined minimum level.

4. Method according to claim 1, wherein the levels of the motor supply current and the motor supply voltage is set such that the incoming power is not exceeded.

5. Method according claim 1, further comprising:

measuring the incoming current and the incoming voltage,

calculating the incoming power based on the measured incoming current and incoming voltage provided by the power supply unit.

6. Method according to claim 1, wherein the motor supply voltage and the motor supply current is provided to the motor as a pulse width modulation signal, and wherein the motor supply voltage level is set by varying the width of the pulse width modulation signal.

7. Method according to claim 1, wherein the motor supply current and the motor supply voltage, in a first state when the measured load requires a motor supply current level that is lower than the incoming current, provide a power to the electric motor that is less than the incoming power level, and in a second state, when the measured load requires a motor supply current level that is equal to or higher than the incoming current, provide a power to the electric motor that is substantially equal to the incoming power level.

8. A height-adjustable furniture arrangement comprising

a power supply unit providing an incoming current and an incoming voltage, which incoming current and incoming voltage set a incoming power level for the height-adjustable furniture arrangement,

at least one electric motor adapted to provide a height-adjusting function in the height-adjustable furniture arrangement, and

a control device adapted to receive the incoming current and the incoming voltage from the power supply unit, and to transform the incoming current to a motor supply current and the incoming voltage to a motor supply voltage, wherein the motor supply current and motor supply voltage are supplied to the at least one electric motor,

wherein the control device is adapted to

measure load on the electric motor, and

when the measured load requires a motor supply current higher than the incoming current for providing the height-adjusting function, setting the levels of the motor supply current and/or the motor supply voltage such that the motor supply current is higher than the incoming current and the motor supply voltage is lower than the incoming voltage.

9. Height-adjustable furniture arrangement according to claim 8, wherein the control device is adapted to set the motor supply current and the motor supply voltage such that the incoming power level is not exceeded.

10. A height-adjustable furniture arrangement comprising

a power supply unit providing an incoming current and an incoming voltage, which incoming current and incoming voltage set an incoming power level for the height-adjustable furniture arrangement,

at least one electric motor adapted to provide a height-adjusting function in the height-adjustable furniture arrangement, and

a control device adapted to receive the incoming current and the incoming voltage from the power supply unit, and to supply a motor supply current and motor supply voltage to the at least one electric motor, wherein the control device further comprises:

a transformation unit for transforming the incoming current and the incoming voltage to the motor supply current and the motor supply voltage supplied to the electric motor,

a measuring unit for measuring load on the electric motor, and

a regulator unit arranged for, when the measured load requires a motor supply current higher than the incoming current for providing the height-adjusting function, setting the levels of the motor supply current and/or the motor supply voltage such that the motor supply current is higher than the incoming current and the motor supply voltage is lower than the incoming voltage, the regulator unit further being arranged for providing the set values for the motor supply voltage and the motor supply current to the transformation unit.