JPH11150873A - Controller for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect residual capacity of a battery with high accuracy, by detecting an offset value of a discharge current detecting sensor whenever non-charging or nondischarging state of a battery is detected without using any detecting means for detecting the charging and discharging currents of batteries. SOLUTION: When an external switch 70 is turned on, a transistor 73 and a power switch 71 are turned on and a power supply voltage is supplied to a microcomputer 72, resulting in an actuation of the micrcomputer 72. When the switch 70 is conducted, the microcomputer 72 converts an analog signal into a digital signal by means of a built-in A/D converter and outputs a delay signal from a timer 76 to a transistor 74. When the microcomputer 72 is initialized, charging states or discharing states of batteries 1 and 3 are discriminated from numerical value of a digital signal indicating whether or not a key switch is turned on and the turning off of a charging switch. When the batteries 1 and 3 are not in non-charging states nor nondischarging states, the microcomputer 72 calculates the residual capacities of the batteries 1 and 3 at regular time intervals by executing normal control operations. While a vehicle is stopped, the offset value of a current sensor 4, etc., calculated when the timer 76 is actuated and the integrated value of self-discharge values are written in a nonvolatile memory and used for the calculation of the residual capacities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric vehicle, and more particularly to a technique for calculating a remaining capacity of a battery.

[0002]

2. Description of the Related Art The remaining capacity of a battery is detected with high accuracy by integrating the charge / discharge current of the battery. For example, Japanese Patent Application Laid-Open No. 4-368432 discloses that even when an ignition key is opened, a discharge current of a battery is intermittently detected for a certain period of time (even when the engine is stopped), and the discharge current is integrated while the engine is stopped. By storing it in a backup memory, it is proposed to realize more accurate calculation of the remaining capacity while reducing the power consumption required for these processes.

[0003]

As described above, in order to detect the remaining capacity of the battery with high accuracy, it is necessary to detect the charge / discharge current of the battery with high accuracy. Therefore, if the current sensor that detects the charge / discharge current of the battery has an offset value, the detection error is accumulated by the offset value and a large remaining capacity error occurs. Required.

However, the offset value of a current sensor mounted on an electric vehicle has a temporally non-negligible fluctuation, which causes a non-negligible remaining capacity error.
As a result, a problem such as overcharging or overdischarging may occur, leading to a decrease in battery performance. Thus, when the time variation of the offset value of the current sensor was examined, it was found that one of the following causes existed.

As a current sensor, a semiconductor magnetic sensor capable of detecting a current with high accuracy is generally used. However, a semiconductor magnetic sensor disposed close to a conductor to be detected includes an external magnetic field, for example, terrestrial magnetism. Magnetic flux leaking from motors, relays, transformers, coils, and the like, and furthermore, magnetic flux from transmission lines and the like act. Further, a magnetic core is wound around the semiconductor magnetic sensor with a slit in order to concentrate a magnetic flux of a current to be detected flowing through a conductor to be detected, and the semiconductor magnetic sensor is housed in the slit. The core absorbs an external magnetic field and generates an offset value in the semiconductor magnetic sensor in the same manner as described above, and the external magnetic field also fluctuates as the vehicle travels, and the offset value fluctuates.

In addition, when a strong external magnetic field acts on the core, a residual magnetic field remains in the core even after the strong external magnetic field is eliminated, and the offset value similarly occurs and varies. Eventually, in the current sensor that detects the charge / discharge current of the battery of the electric vehicle, the offset value slightly fluctuates due to the movement of the vehicle, but when the charge / discharge current of the battery is integrated to detect the remaining capacity of the battery, the charge current becomes Although the offset current and the discharge current cancel each other, the offset value is integrated over time, so that the offset value becomes gradually larger, resulting in a large error in the remaining capacity. If the offset value is constant and does not change, it is measured, stored, and subtracted from the measured value of the charging / discharging current, and there is no problem. However, in an electric vehicle, the magnetic source inside the vehicle and the magnetic state outside the vehicle change spatially and temporally, and this causes a temporal change in the offset value, so that simple offset value storage cannot be canceled.

[0007] After all, since the electric vehicle is the vehicle itself, it is difficult to avoid the fluctuation of the offset value due to the change of the surrounding environment of the current sensor. The present invention has been made in view of the above problems, and has as its object to provide an electric vehicle control device capable of detecting the battery capacity of an electric vehicle with high accuracy.

[0008]

According to the first aspect of the present invention, a predetermined non-charging / discharging state of the battery is detected by means other than the current detecting means.
An offset value of a current sensor that detects a discharge current of a battery mounted on the electric vehicle is detected. This allows
Even if the offset value fluctuates with time due to space movement of the electric vehicle or changes over time of the current sensor, the discharge current and the charging current of the battery mounted on the electric vehicle can be detected with high accuracy. It is possible to solve such a problem that the estimation of the remaining capacity of the battery varies due to the integration of the errors, and the overcharge and overdischarge occur, and the effective use of the battery is hindered.

[0009] The non-charge / discharge state of the electric vehicle can be detected as a non-charge / discharge state when both the conditions of turning off the key switch and turning off the charge switch for instructing charging are satisfied. However, other means can be employed. In such a non-charging / discharging state, the output value of the current detecting means (current sensor) for detecting the charging / discharging current of the battery is an offset value, so that it can be detected accurately.

[0010] In a preferred aspect of this configuration, the current detecting means has a magnetic core surrounding a conductor through which a current to be detected flows, and a magnetic sensor for detecting a magnetic flux flowing through the magnetic core. With this configuration, it is possible to favorably cancel the influence of the external magnetic field change including the geomagnetism due to the vehicle movement, in addition to the time change of the leakage magnetic field from the vehicle-mounted magnetism generating device.

According to a second aspect of the present invention, in the control apparatus for an electric vehicle according to the first aspect, an offset value is periodically detected and stored in a non-volatile memory during a period in which a non-charge / discharge state is detected. With this configuration, during the offset value non-detection period in the non-charge / discharge state, the application of the power supply voltage to the control device is turned off, and the battery can be prevented from being consumed. For example, it is possible to reduce unnecessary power consumption of a battery by starting up a battery control controller having a microcomputer configured to process a signal by a timer periodically when the vehicle is stopped and storing the result in a nonvolatile memory. it can.

According to a third aspect of the present invention, in the control apparatus for an electric vehicle according to the second aspect, during the non-charge / discharge state period, the operation of periodically calculating the amount of self-discharge of the battery, and The detection storage operation is performed together. With this configuration, the offset value is detected and stored when the self-discharge amount of the battery is periodically started during the non-charge / discharge state period, so that the additional battery power consumption can be almost ignored.

According to a fourth aspect of the present invention, in the control apparatus for an electric vehicle according to the second aspect, the control unit (usually a microcomputer) periodically starts the work of detecting the self-discharge amount and the offset value in the non-charge / discharge state. At the same time, power supply voltage application to the control unit is cut off, and power saving is performed. The power supply unit includes a power switch, a timer, and a timer input control switch. The power switch is controlled by the timer to intermittently control power supply from the battery to the control unit.
On the other hand, when the control section determines that the activation of the control section is caused by the timer, the control section executes a predetermined operation and then starts the timer and shuts off the power switch.

[0014] In this manner, the control device of the electric vehicle is started up periodically to perform a predetermined operation by simply adding a simple configuration such as a timer without adding any complicated circuit means. Until the start of the work, the control device can be shut down and its power consumption can be used only for the timer, to prevent the battery of the electric vehicle from being consumed, and the estimation of the power storage amount due to the accumulation of the power consumption is inaccurate. Can be suppressed.

According to a fifth aspect of the present invention, there is provided the electric vehicle control device according to the fourth aspect, further comprising an external input control switch operated by an external signal, a control unit input control switch operated by the control unit, and a timer. A timer input control switch to be operated is connected in parallel, and the power switch is intermittently controlled by its output. If you do this,
During the power supply interruption period to the control unit, each of these control switches
Since no current is consumed, power consumption can be further reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the electric vehicle charging apparatus of the present invention will be described with reference to the drawings. (Circuit Configuration) A control device of the main battery 1 in the hybrid electric vehicle of this embodiment will be described with reference to a block diagram shown in FIG.

A high-voltage (about 300 V) main battery 1 supplies power to a traveling power control circuit 2 including a traveling motor. 3
Is a low-voltage auxiliary battery, 4 is a current sensor for detecting the charge / discharge current of the main battery 1, 7 is an ECU which is a controller for battery management, and 70 is an external switch comprising a key switch. The configuration of the ECU 7 will be described below.

Reference numeral 71 denotes a transistor (power switch) supplied with a power supply voltage from the auxiliary battery 3, 72 denotes a microcomputer (control unit), and 73 denotes an external switch 70 provided between the control terminal of the power switch 71 and ground. A grounded-emitter transistor (external input control switch) which is rendered conductive by conduction; 74, a grounded-emitter transistor (timer input control switch) which is connected in parallel with the transistor 73;
Reference numeral 5 denotes a common-emitter transistor (control unit input control switch) connected in parallel with the transistors 73 and 74 and controlled by the microcomputer 72. Reference numeral 76 denotes a timer, which is directly supplied with power from the auxiliary battery 3, counts clock pulses generated by a built-in clock generator in response to a count start command signal input from the microcomputer 72, and delays the count when the count reaches a predetermined value. A high-level voltage forming a signal is output to the transistor 74.

The operation of the ECU 7 will be described below. When the external switch 70 is turned on, the transistor 73 and the power switch 71 are turned on, the power supply voltage is supplied to the microcomputer 72, and the microcomputer 72 starts. The conduction state of the external switch 70 is input to the microcomputer 72, and the built-in AD
It is converted to a digital signal by a converter. When a delay signal is output from the timer 76 to the transistor 74 and the power switch 71 is turned on, the power supply voltage is supplied to the microcomputer 72 in the same manner as described above, and the microcomputer 72 starts up.

The operation of the microcomputer (control section) 72 will be described with reference to FIG. When the microcomputer 72 is started in one of the two types of start modes, initial settings are first made (S100), and then it is detected whether the battery is in a non-charging / discharging state (electric vehicle is in a halt state). . In the non-charge / discharge state, in this embodiment, it is determined whether a key switch (corresponding to a conventional ignition switch) is turned on by determining whether the numerical value of the digital signal is equal to or greater than a predetermined value, and not shown. The suspension of the charging device for charging the main battery 1 and the auxiliary battery 3 from the commercial power supply is determined by the fact that a charging switch (not shown) is turned off (S102). If it is not in the non-charge / discharge state, a normal control operation (normal processing) is executed (S104). In this normal process, the remaining capacity of the batteries 1 and 3 is calculated at least at regular intervals.

On the other hand, if it is in the non-charge / discharge state,
And the current sensors 100 and 30
The offset value (output signal value) of 0 is detected and written in the built-in nonvolatile memory (S105), and then the temperature of the microcomputer 72 (detected by the built-in thermistor) is measured, and this temperature and the self- The self-discharge amount of these batteries 1 and 3 is estimated from a built-in map indicating the relationship with the discharge amount, and is added to the accumulated value of the self-discharge amount accumulated last time to obtain the current accumulated value (S106). This is written into the nonvolatile memory included in the microcomputer 72 (S108), and thereafter, a count start command signal is output to the timer 76 (S110).
The transistor 75 is turned off (S112).

At this point, since the transistor 74 is off, the power switch 71 is turned off by turning off the transistor 75, and the controller 71 is turned off. Next, a case where the external switch 70 is shut off during the execution of the normal control operation executed in S104 will be described. This control is performed by an interrupt routine (see FIG. 3) performed at predetermined short intervals. At the same time as the activation of the interrupt routine, it is checked whether or not the normal processing is being performed (S2).
00), otherwise return to the main routine. If so, it is checked whether or not the external switch 70 is turned off (S202). If the external switch 70 is turned on, the routine returns to the main routine (see FIG. 1).
If it is shut off, necessary information during normal processing is written to the nonvolatile memory (S204), a count start command signal is output to the timer 76 (S206), and the transistor 75 is shut off (S208).

The offset value of the current sensor 4 and the like calculated when the timer is started while the vehicle is at rest (non-charge / discharge state) and the integrated value of the integrated self-discharge amount are written in the nonvolatile memory, It is used for calculating the remaining capacity thereafter. In the above embodiment, the battery 1
Although the self-discharge amount of No. 3 was obtained by a map according to the temperature detected each time the timer was started, it is also possible to simply calculate the self-discharge amount simply by the self-discharge time.

Further, in the above embodiment, the description of the method of calculating the remaining capacity itself is omitted, but various methods can be adopted for calculating or estimating the remaining capacity of the battery. However, the detection and integration of at least the battery charge / discharge current and the discharge current are indispensable for the highly accurate calculation of the remaining capacity, and the periodic cancellation of the offset value according to this embodiment is effective in improving the accuracy.

In addition, in addition to the non-charge / discharge state (vehicle halt state) described in this embodiment, the fluctuation of the offset value of the current sensor 4 and the like and the self-discharge also occur during the charge / discharge state of the battery 1. While performing (S200), offset value detection and self-discharge amount detection are periodically performed,
Preferably, an integration is performed. Specifically, S105 and S106 may be executed during the normal process (S200) shown in FIG. 6 or periodically immediately before S204.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a battery control device for a hybrid electric vehicle according to the present invention.

FIG. 2 is a flowchart showing the operation of the ECU 7;

FIG. 3 is a flowchart showing the operation of the ECU 7;

DESCRIPTION OF SYMBOLS 1 is a main battery (battery), 3 is an auxiliary battery (battery), 4 is a current sensor, 7 is an ECU (running motor control means, remaining capacity calculation means, battery charge / discharge control means, Charge / discharge state detection means, offset value detection storage means, self-discharge amount calculation means), 71 is a power switch, 72 is a control unit,
73 is an external input control switch, 74 is a timer input control switch, 75 is a control unit input control switch, and 76 is a timer.

Claims (5)

[Claims] 1. A traveling motor control means for controlling the output of a traveling motor supplied from a battery, a current detecting means for detecting a charging / discharging current of the battery, and a battery remaining based on the detected discharging current. A control device for an electric vehicle, comprising: a remaining capacity calculation unit that determines a capacity; and a battery charge / discharge control unit that controls charging / discharging of the battery based on the determined remaining capacity. A non-charge / discharge state detecting means for detecting a predetermined non-charge / discharge state; and detecting an output value of the current detecting means each time the non-charge / discharge state is detected, and storing the output value as a charge / discharge current correction offset value. A control device for an electric vehicle, comprising: an offset value detection storage unit. 2. The control device for an electric vehicle according to claim 1, wherein the offset value detection storage means periodically detects the offset value within a period for detecting the non-charge / discharge state and stores the offset value in a nonvolatile memory. A control device for an electric vehicle. 3. The control device for an electric vehicle according to claim 2, further comprising: a self-discharge amount calculating unit that periodically calculates a self-discharge amount of the battery within a period of detecting the non-charge / discharge state. The control device for an electric vehicle, wherein the value detection storage means performs the detection storage of the offset value continuously with the calculation of the self-discharge amount. 4. The control device for an electric vehicle according to claim 2, wherein the control unit includes the remaining capacity calculation unit and the battery charge / discharge control unit, and the control unit is interposed between the battery and the control unit. A power supply unit for intermittently controlling supply of power current from a battery to the control unit, wherein the power supply unit is interposed between the battery and the control unit and intermittently supplies power from the battery to the control unit. A power switch to be controlled; a timer that is supplied with power from the battery without passing through the power switch and outputs a delay signal a predetermined time after the input of a predetermined count start command signal; and a power supply that receives the delay signal from the timer. A timer input control switch for conducting a switch, wherein the control unit has determined that the self-startup is due to the timer input control switch. In this case, a periodic operation including the self-discharge amount calculation and the offset value detection storage is performed, and after the periodic operation is completed, the count start command signal is output to the timer and the power switch is shut off. Electric vehicle control device 5. The control device for an electric vehicle according to claim 4, wherein an external input control switch that is activated by an external signal to conduct the power switch, and a control unit that is activated by the control unit and conducts the power switch. An electric vehicle control device comprising: an input control switch in parallel with the timer input control switch.