Intelligent switch for connecting power to a load

• US 20040021427A1
• Filed: 12/12/2002
• Published: 02/05/2004
• Est. Priority Date: 06/13/2000
• Status: Active Grant

• Current Assignee: Abraham Carl Greyling, Brandt Aucamp, Frederick Johannes Bruwer
• Original Assignee: Abraham Carl Greyling, Brandt Aucamp, Frederick Johannes Bruwer
• Inventors: Bruwer, Frederick Johannes, Greyling, Abraham Carl, Aucamp, Brandt
• Granted Patent: US 7,119,459 B2
• Time in Patent Office: Days
• US Class Current: 315/200A
• CPC Class Codes: H02J 2207/10 Control circuit supply, e.g. means for supplying power to the control circuit
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02M 3/157 with digital control

Abstract

A switching circuit includes a microchip which, in response to a signal from a signal switch, controls the operation of a power switch which, when closed, connects a load to a battery. The microchip can monitor the status of the battery and control the power switch to ensure optimum operation of the load and optimum usage of the energy in the battery. The microchip can control the connection of the load to the battery in different ways according to the manner of operation of the signal switch.

Claims

1. A switching circuit for controlling the supply of power from an exhaustible power source to a load which includes a control circuit, a power switch which is controlled by the control circuit or a man-machine-interface (MMI) and which, when closed, connects the power source to the load, and at least one signal switch input to the control circuit which can detect if a switch is open or closed and does not form a serial part of an energy transfer circuit from the power supply to the load and wherein the control circuit further provides at least one function selected from the following functions:

(a) a power source level indication which is determined by comparing a fixed reference voltage to a closed circuit supply voltage and which is displayed to a user, even at times when the load is disconnected from the power source; and

(b) a function wherein the control circuit compares the voltage of the power source to a fixed reference voltage and, in response to the comparison, controls a duty cycle of the power switch to provide a substantially constant supply of power from the power source to the load over a voltage range of the power source.

2. A switching circuit according to claim 1(b) wherein the level of said substantially constant supply of power is determined in accordance with a level selected by means of a signal at the signal switch input.

3. A switching circuit according to claim 1 or 2 wherein the control circuit provides at least one further function in response to a sequence of activation signals at the signal switch input.

4. A switching circuit according to claim 3 wherein the sequence of activation signals is changed dynamically to select off on the next activation or deactivation signal once any specific selection from the functions has been active for a predetermined period of time.

5. A switching circuit according to any one of claims 1 to 4 wherein the control circuit monitors the voltage of the power source and when the power source voltage drops below an operating voltage of at least one element of the control circuit, the power switch is controlled directly by a signal at the signal switch input to connect the power source to load.

6. A switching circuit according to any one of claims 1 to 5 wherein the power source level indicator also functions as a find-in-the-dark indicator.

7. A switching circuit according to any one of claims 1 to 6 wherein the control circuit monitors the voltage of the power source at predetermined intervals in the “

on” and

in the “

off”

state of the power switch.

8. A switching circuit according to claim 7 wherein a load is automatically connected to the power source before the voltage of the power source is measured.

9. A switching circuit according to any one of claims 1 to 8 wherein the power source level indication is additionally based on a measurement of the level of the supply voltage when the power switch is not conducting.

10. A switching circuit according to any one of claims 1 to 9 wherein the load is an electric motor and the duty cycle of the power switch is controlled to achieve a substantially constant operation of the motor over a range of power source levels.

11. A switching circuit according to any one of claims 1 to 9 wherein the load is a lighting element and the duty cycle of the power switch is controlled to achieve a substantially constant illumination level of the lighting element over a range of power source levels.

12. A switching circuit according to any one of claims 1 to 11 wherein the power source level indication additionally gives an indication of a selected function or made of the control circuit.

13. A switching circuit according to any one of claims 1 to 12 which is packaged within the housing of a conventional electromechanical switch.

14. A switching circuit according to any one of claims 1 to 13 wherein the substantially constant power supplied to the load is achieved by stepping up the input voltage to a higher voltage for the load.