Internal combustion engine stop controller and stop control method

• US 7,822,535 B2
• Filed: 04/20/2007
• Issued: 10/26/2010
• Est. Priority Date: 04/24/2006
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Yaguchi, Hideaki
• Primary Examiner(s): Kwon; John T
• Application Number:
  US12/226,053
• Publication Number:
  US 20090171554A1
• Time in Patent Office: 1,285 Days
• Field of Search: 701/101, 701/102, 701/112, 123/319, 123/320, 123/325, 123/331, 123/334, 123/335, 123/339.14, 180/65.21, 180/65.265, 180/65.28
• US Class Current: 701/112
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2260/54 Energy consumption estimation
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/25 by controlling the electric load
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• 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 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2710/244 Charge state
• CPC Class Codes: B60W 2710/248 Current for loading or unloading
• CPC Class Codes: F02D 29/06 peculiar to engines driving electric generators
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

When engine stop control is executed, an ECU estimates input power to a power storage device in accordance with an estimation of power generated by a generator and estimation of total power consumption of circuitry from the generator to the power storage device in the current state of operation. Further, the ECU compares the estimated input power with a tolerable input power to the storage device. When the generated power is excessive, the state of operation of the circuitry is changed such that the total power consumption by the circuitry increases, and then, torque output of the generator is permitted, to attain desired deceleration at the engine stop. Accordingly, in the engine stop control in which stopping force is generated by the power generating operation by the rotating electric machine, excessive charging caused by excessive power input to the power storage device can be prevented.

Claims

1. A stop controller for an internal combustion engine in a vehicle including the internal combustion engine operated on fuel combustion, a first rotating electric machine formed to generate stopping force for said internal combustion engine by a power generating operation when said internal combustion engine is stopped, a second rotating electric machine capable of generating vehicle driving force in parallel with said internal combustion engine, and a power exchange circuit for exchanging power between a power storage device and said first and second rotating electric machines, wherein

said power exchange circuit includes

a converter provided between said power storage device and a DC power line, for exchanging DC power between said power storage device and said DC power line by a switching operation of a switching element such that the voltage on said DC power line matches a voltage command value,

a first inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said first rotating electric machine, by switching operations of a plurality of switching elements, and

a second inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said second rotating electric machine, by switching operations of a plurality of switching elements;

said stop controller comprising;

input limit setting means for setting tolerable input power of said power storage device;

power generation estimating means for estimating power generation when said first rotating electric machine generates prescribed said stopping force while said internal combustion engine is stopped;

input power estimating means for estimating total power consumption based on a sum of estimated power consumption by said power exchange circuit and said first and second rotating electric machines in the current operation state, when said internal combustion engine is stopped, and based on the estimated total power consumption and the power generation estimated by said power generation estimating means, for estimating input power to said power storage device;

first stop control means for generating an output torque command for said first rotating electric machine such that said first rotating electric machine generates said prescribed stopping force in said current operation state, when the input power estimated by said input power estimating means is within said tolerable input power;

loss control means for controlling an operation state of said power exchange circuit such that power consumption by said power exchange circuit increases, when the input power estimated by said input power estimating means exceeds said tolerable input power;

input power predicting means for predicting input power to said power storage device when the power consumption by said power exchange circuit is increased to an upper limit by said loss control means, if the input power estimated by said input power estimating means exceeds said tolerable input power;

power generation reducing means for modifying, when the input power estimated by said input power estimating means exceeds said tolerable input power and the input power predicted by said input power predicting means exceeds said tolerable input power, the output torque command for said first rotating electric machine from a value of said first stop control means, so that power generation by said first rotating electric machine is reduced; and

second stop control means for generating said output torque command comparable to said first stop control means, together with control of said operation state by said loss control means, when the input power estimated by said input power estimating means exceeds said tolerable input power and the input power predicted by said input power predicting means is within said tolerable input power.

2. The stop controller for an internal combustion engine according to claim 1, further comprising:

voltage determining means for comparing an output voltage of said power storage device with a management upper limit voltage; and

power generation stopping means for stopping, when it is determined by said voltage determining means that the output voltage of said power storage device exceeds said management upper limit voltage, the power generation operation by said first rotating electric machine when said internal combustion engine is stopped.

3. The stop controller for an internal combustion engine according to claim 1, wherein

said vehicle further includes a second rotating electric machine capable of generating vehicle driving force in parallel with said internal combustion engine;

said power exchange circuit includes

a converter provided between said power storage device and a DC power line, for exchanging DC power between said power storage device and said DC power line by a switching operation of a switching element,

a first inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said first rotating electric machine, by switching operations of a plurality of switching elements, and

a second inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said second rotating electric machine, by switching operations of a plurality of switching elements;

said switching operation in said converter is controlled such that voltage of said DC power line matches a voltage command value; and

said loss control means executes, when the input power estimated by said input power estimating means exceeds said tolerable input power, at least one of (1) increase of switching frequency of said switching element of said converter, (2) increase of switching frequency of each of said switching elements of said first inverter, (3) increase of switching frequency of each of said switching elements of said second inverter, and (4) increase of the voltage command value of said converter.

4. The stop controller for an internal combustion engine according to claim 1, wherein

said power storage device is implemented by a lithium ion secondary battery.

5. The stop controller for an internal combustion engine according to claim 1, wherein

said input power estimating means estimates said total power consumption, using at least a first map for estimating power loss at said first rotating electric machine using torque and rotation number of said first rotating electric machine as arguments, a second map for estimating power loss and effective power at said second rotating electric machine using torque and rotation number of said second rotating electric machine as arguments, a third map for estimating power loss at said first inverter based on the torque and rotation number of said first rotating electric machine, the voltage on said DC power line and switching frequency of said first inverter, a fourth map for estimating power loss at said second inverter based on the torque and rotation number of said second rotating electric machine, the voltage on said DC power line and switching frequency of said second inverter, and a fifth map for estimating, power loss at said converter based on the voltage of said DC power line, switching frequency of said converter and current of said power storage device.

6. The stop controller for an internal combustion engine according to claim 5, wherein

said input power estimating means estimates said total power consumption further using a sixth map for estimating a change in stored power of a smoothing capacitor connected to said DC power line, based on the voltage on said DC power line.

7. The stop controller for an internal combustion engine according to claim 5, wherein

said input power estimating means estimates said total power consumption further using a seventh map for estimating power consumption by a load, based on a state of operation of the load receiving power supply from said DC power line.

8. The stop controller for an internal combustion engine according to claim 7, wherein

said loss control means further changes the state of operation of said load so that power consumption by said load increases, when the input power estimated by said input power estimating means exceeds said tolerable input power.

9. The stop controller for an internal combustion engine according to claim 1, wherein

said power generation reducing means sets an amount of modifying said output torque command, based on an excess of predicted input power predicted by said input power predicting means with respect to said tolerable input power.

10. A stop control method for an internal combustion engine in a vehicle including the internal combustion engine operated on fuel combustion, a first rotating electric machine formed to generate force for stopping said internal combustion engine by a power generating operation when said internal combustion engine is stopped, a second rotating electric machine capable of generating vehicle driving force in parallel with said internal combustion engine, and a power exchange circuit for exchanging power between a power storage device and said first and second rotating electric machines, wherein

said power exchange circuit includes

a converter provided between said power storage device and a DC power line, for exchanging DC power between said power storage device and said DC power line by a switching operation of a switching element, such that the voltage on said DC power line matches a voltage command value,

a first inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said first rotating electric machine, by switching operations of a plurality of switching elements, and

a second inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said second rotating electric machine, by switching operations of a plurality of switching elements;

said stop control method comprising the steps of;

setting tolerable input power of said power storage device;

estimating power generation when said first rotating electric machine generates prescribed said stopping force while said internal combustion engine is stopped;

estimating total power consumption based on a sum of estimated power consumption by said power exchange circuit and said first and second rotating electric machines in the current operation state, when said internal combustion engine is stopped, and based on the estimated total power consumption and the estimated power generation, for estimating input power to said power storage device;

generating an output torque command for said first rotating electric machine such that said first rotating electric machine generates said prescribed stopping force in said current operation state, when the input power estimated at said step of estimating is within said tolerable input power;

controlling an operation state of said power exchange circuit such that power consumption by said power exchange circuit increases, when the estimated input power exceeds said tolerable input power;

predicting input power to said power storage device when the power consumption by said power exchange circuit is increased to an upper limit at said step of controlling, if the estimated input power exceeds said tolerable input power;

modifying, when the input power estimated at said step of estimating exceeds said tolerable input power and the input power predicted at said step of predicting exceeds said tolerable input power, the output torque command for said first rotating electric machine from a value at said step of generating, so that power generation by said first rotating electric machine is reduced; and

generating said output torque command comparable to that of said step of generating, together with control of said operation state at said step of controlling, when the input power estimated at said step of estimating exceeds said tolerable input power and the input power predicted at said step of predicting is within said tolerable input power.

11. The stop control method for an internal combustion engine according to claim 10, further comprising the steps of:

comparing an output voltage of said power storage device with a management upper limit voltage; and

stopping, when it is determined at said step of comparing that the output voltage of said power storage device exceeds said management upper limit voltage, the power generation operation by said first rotating electric machine when said internal combustion engine is stopped.

12. The stop control method for an internal combustion engine according to claim 10, wherein

said vehicle further includes a second rotating electric machine capable of generating vehicle driving force in parallel with said internal combustion engine;

said power exchange circuit includes

a converter provided between said power storage device and a DC power line, for exchanging DC power between said power storage device and said DC power line by a switching operation of a switching element,

a first inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said first rotating electric machine, by switching operations of a plurality of switching elements, and

a second inverter formed to perform power-conversion between DC power on said DC power line and AC power input to/output from said second rotating electric machine, by switching operations of a plurality of switching elements;

said switching operation in said converter is controlled such that voltage of said DC power line matches a voltage command value; and

at said step of controlling, when the estimated input power exceeds said tolerable input power, at least one of (1) increase of switching frequency of said switching element of said converter, (2) increase of switching frequency of each of said switching elements of said first inverter, (3) increase of switching frequency of each of said switching elements of said second inverter, and (4) increase of the voltage command value of said converter, is executed.

13. The stop control method for an internal combustion engine according to claim 10, wherein

said power storage device is implemented by a lithium ion secondary battery.

14. The stop control method for an internal combustion engine according to claim 10, wherein

at said step of estimating said input power, said total power consumption is estimated by using at least a first map for estimating power loss at said first rotating electric machine using torque and rotation number of said first rotating electric machine as arguments, a second map for estimating power loss and effective power at said second rotating electric machine using torque and rotation number of said second rotating electric machine as arguments, a third map for estimating power loss at said first inverter based on the torque and rotation number of said first rotating electric machine, the voltage on said DC power line and switching frequency of said first inverter, a fourth map for estimating power loss at said second inverter based on the torque and rotation number of said second rotating electric machine, the voltage on said DC power line and switching frequency of said second inverter, and a fifth map for estimating power loss at said converter based on the voltage of said DC power line, switching frequency of said converter and current of said power storage device.

15. The stop control method for an internal combustion engine according to claim 14, wherein

at said step of estimating said input power, said total power consumption is estimated further using a sixth map for estimating a change in stored power of a smoothing capacitor connected to said DC power line, based on the voltage on said DC power line.

16. The stop control method for an internal combustion engine according to claim 14, wherein

at said step of estimating said input power, said total power consumption is estimated further using a seventh map for estimating power consumption by a load, based on a state of operation of the load receiving power supply from said DC power line.

17. The stop control method for an internal combustion engine according to claim 16, wherein

at said step of control, the state of operation of said load is changed so that power consumption by said load increases, when the input power estimated at said step of estimating input power exceeds said tolerable input power.

18. The stop control method for an internal combustion engine according to claim 10, wherein

at said step, an amount of modifying said output torque command is set, based on an excess of predicted input power predicted at said step of predicting with respect to said tolerable input power.