Method and system of requesting engine on/off state in a hybrid electric vehicle

• US 7,216,729 B2
• Filed: 09/19/2003
• Issued: 05/15/2007
• Est. Priority Date: 09/19/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: McGee, Ryan A., Syed, Fazal U., Anthony, Joseph W.
• Primary Examiner(s): VANAMAN, FRANK BENNETT
• Application Number:
  US10/605,290
• Publication Number:
  US 20050061563A1
• Time in Patent Office: 1,334 Days
• Field of Search: 180/65.2, 180/65.3, 180/65.4, 903/941, 903/943, 701/22
• US Class Current: 180/65.28
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 903/905 Combustion engine

Abstract

A method and system of engine start/stop control for a HEV that monitors the battery and requests a specific engine state based on condition of the battery. A battery parameter such as discharge power limit (DPL) or state of charge (SOC) is compared with a set of threshold levels including a MIN level, an ON level, and an OFF level and the result of the comparison provides inputs to a state machine. The state machine includes an ON state, an OFF state and a OPPORTUNISTIC state. The machine transitions between the various states as a function of DPL and SOC relative to the sets of threshold levels.

Claims

1. A method of controlling a hybrid electric vehicle powertrain having a power unit, an energy storage battery, and a controller responding to powertrain operating parameters including discharge power limit (DPL) and battery state of charge (SOC), the controller including a state machine having a plurality of states and an arbitrator for effecting a response to state machine change requests in accordance with the powertrain operating parameters, the method comprising a sequence of the following steps:

(a) monitoring the powertrain operating parameters;

(b) determining the values of the discharge power limit (DPL) and the state of charge (SOC) of the energy storage battery;

(c) if the state machine is in an OFF state, which requests that the power unit be off, and the DPL is less than an ON level, causing the state machine to transition from the OFF state to an OPPORTUNISTIC state, which requests that the power unit be kept on if already on;

(d) if the state machine is in an ON state, which requests that the power unit be on, and the DPL is greater than the ON level, causing the state machine to transition from the ON state to the OPPORTUNISTIC state;

(e) if the state machine is in the OPPORTUNISTIC state and the DPL is less than a MIN level, the MIN level being less than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the ON state; and

(f) if the state machine is in the OPPORTUNISTIC state and the DPL is greater than an OFF level, the OFF level being greater than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the OFF state.

2. A method of controlling a hybrid electric vehicle powertrain having a power unit, an energy storage battery, and a controller responding to powertrain operating parameters including discharge power limit (DPL) and battery state of charge (SOC), the controller including a state machine having a plurality of states and an arbitrator for effecting a response to state machine change requests in accordance with the powertrain operating parameters, the method comprising a sequence of the following steps:

(a) monitoring the powertrain operating parameters;

(b) determining the values of the discharge power limit (DPL) and the state of charge (SOC) of the energy storage battery;

(c) if the state machine is in an OFF state, which requests that the power unit be off, and the SOC is less than an ON level, causing the state machine to transition from the OFF state to an OPPORTUNISTIC state, which requests that the power unit be kept on if already on;

(d) if the state machine is in an ON state, which requests that said power unit be on, and the SOC is greater than the ON level, causing the state machine to transition from the ON state to the OPPORTUNISTIC state;

(e) if the state machine is in the OPPORTUNISTIC state and the SOC is less than a MIN level, the MIN level being less than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the ON state; and

(f) if the state machine is in the OPPORTUNISTIC state and the SOC is greater than an OFF level, the OFF level being greater than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the OFF state.

3. A method of controlling a hybrid electric vehicle powertrain having a power unit, an energy storage battery, and a controller responding to powertrain operating parameters including discharge power limit (DPL) and battery state of charge (SOC), the controller including a state machine having a plurality of states and an arbitrator for effecting a response to state machine change requests in accordance with the powertrain operating parameters, the method comprising a sequence of the following steps:

(a) monitoring the powertrain operating parameters;

(b) determining the values of the discharge power limit (DPL) and the state of charge (SOC) of the energy storage battery;

(c) if the state machine is in an OFF state, which requests that the power unit be off, and the DPL or SOC is less than an ON level, causing the state machine to transition from the OFF state to an OPPORTUNISTIC state, which requests that the power unit be kept on if already on;

(d) if the state machine is in an ON state, which requests that said power unit be on, and the DPL or SOC is greater than the ON level, causing the state machine to transition from the ON state to the OPPORTUNISTIC state;

(e) if the state machine is in the OPPORTUNISTIC state and the DPL or SOC is less than a MIN level, the MIN level being less than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the ON state; and

(f) if the state machine is in the OPPORTUNISTIC state and the DPL or SOC is greater than an OFF level, the OFF level being greater than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the OFF state.

4. A method of controlling a hybrid electric vehicle powertrain having a power unit, an energy storage battery, and a controller responding to powertrain operating parameters including discharge power limit (DPL) and battery state of charge (SOC), the controller including a state machine having a plurality of states and an arbitrator for effecting a response to state machine change requests in accordance with the powertrain operating parameters, the method comprising a sequence of the following steps:

(a) monitoring the powertrain operating parameters;

(b) determining the values of the discharge power limit (DPL) and the state of charge (SOC) of the energy storage battery;

(c) if the state machine is in an OFF state, which requests that the power unit be off, and the DPL is less than an ON level, causing the state machine to transition from the OFF state to an OPPORTUNISTIC state, which requests that the power unit be kept on if already on;

(d) if the state machine is in an ON state, which requests that the power unit be on, and the DPL is greater than the ON level, causing the state machine to transition from the ON state to the OPPORTUNISTIC state;

(e) if the state machine is in the OPPORTUNISTIC state and the DPL is less than a MIN level, the MIN level being less than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the ON state; and

(f) if the state machine is in the OPPORTUNISTIC state and the DPL is greater than an OFF level, the OFF level being greater than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the OFF state;

wherein the step of monitoring the powertrain operating parameters includes monitoring the drive mode of the powertrain to determine whether it is in reverse drive or forward drive, the ON level and the OFF level being dependent on the drive mode of a vehicle transmission.

5. A method of controlling a hybrid electric vehicle having a power unit, an energy storage battery, a transmission, and a controller including a state machine having a plurality of states including an ON state, which requests that said power unit be on, an OFF state, which requests that said power unit be off, and an OPPORTUNISTIC state, which requests that said power unit be kept on if already on, the method comprising a sequence of the following steps:

(a) determining the values of a discharge power limit (DPL) and a state of charge (SOC) of the energy storage battery;

(b) if the state machine is in the ON state and the DPL or SOC is greater than an ON level, causing said machine to transition from the ON state to the OPPORTUNISTIC state;

(c) if the state machine is in said OFF state and the DPL or SOC is less than an ON level, causing the state machine to transition from the OFF state to the OPPORTUNISTIC state;

(d) if the state machine is in the OPPORTUNISTIC state and the DPL or SOC is less than a MIN level, wherein the MIN level is less than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the ON state; and

(e) if said machine is in the OPPORTUNISTIC state and the DPL or SOC is greater than an OFF level, wherein the OFF level is greater than the ON level, causing the state machine to transition from the OPPORTUNISTIC state to the OFF state.