Control algorithm for backup power system

• US 20070213876A1
• Filed: 03/09/2006
• Published: 09/13/2007
• Est. Priority Date: 03/09/2006
• Status: Active Grant

• Current Assignee: Lennox Manufacturing Inc. (Lennox International Incorporated)
• Original Assignee: Lennox Manufacturing Inc. (Lennox International Incorporated)
• Inventors: Warren, Donald, Smith, John
• Granted Patent: US 7,389,159 B2
• Time in Patent Office: Days
• US Class Current: 700/276
• CPC Class Codes: G05D 23/1924 using thermal energy, the availability of which is aleatory

Abstract

A method for controlling fossil fuel fired heating systems according to an improved adaptive cyclical control method when operating on backup (auxiliary DC) electrical power. Battery life is prolonged when used in conjunction with such improved method. Operating characteristics of the heating equipment and home or building being heated are monitored and stored in electronic memory during normal periods of operation when grid power is available. These characteristics are used to create control algorithms that are in turn specific to the system, as defined by the heating equipment and conditioned space. When the grid power is lost the control algorithms select the optimal heating mode, determine optimal cycle duration, and estimate the time to exhaustion of the remaining backup power. Operation is divided into sequential modes. When a prolonged low voltage period is detected, the backup power control initiates a short-term preliminary energy conservation mode. As the outage persists, the control transitions to intermediate and long-term energy conservation modes until the backup power is exhausted or grid power is restored.

Claims

1. A method for controlling a heating unit operating on backup electrical power comprising the steps of:

(a) operating the heating unit according to at least one comfort mode when an estimate of remaining backup electrical power is above a threshold value; and

,

(b) operating the heating unit according to a long-term electrical power protection mode when an estimate of remaining backup electrical power is below a threshold value.

2. The method of claim 1 wherein the control sequence for a heating unit operating on backup electrical power comprising the steps of:

(a) operating the heating unit according to a short-term comfort mode when an estimate of remaining backup electrical power is above a threshold value and when a cycle count is below a pre-determined short-term limit;

(b) operating the heating unit according to a long-term comfort mode when an estimate of remaining backup electrical power is above a threshold value, when a cycle count is above a pre-determined short-term limit, and when a cycle count is below a pre-determined long-term limit; and

(c) operating the heating unit according to a long-term electrical power protection mode when an estimate of remaining backup electrical power is below a threshold value or when a cycle count is above a pre-determined long-term limit.

3. The method of claim 2 wherein the heating unit is operated according to a long-term electrical power protection mode if a comfort mode override switch is set.

4. The method of claim 2 wherein steps (a) through (c) are not performed until normal electrical grid line power is disrupted for a pre-determined amount of time.

5. A method for determining the optimum operating mode, number of cycles, and the duration of each cycle of the heating unit comprising the steps of:

storing operating mode (High Heat, Low Heat, Fan Only) at multiple points in time;

storing values of indoor temperature at multiple points in time;

storing values of outdoor temperature at multiple points in time; and

,

storing electrical power used by the heating unit at multiple points in time.

6. The method of claim 5 wherein said stored data is used to;

construct dynamic heat loss equations for the dwelling;

calculate an optimum heating ratio, defined as the heat provided to the dwelling relative to the electrical power requirement of the heating unit;

estimate time remaining prior to the complete exhaustion of available backup power;

estimate time remaining until the dwelling experiences dangerously low temperatures.