JP2004040921A - Control method for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect short circuit of a main circuit and an open circuit (phase interruption) in an inverter circuit. <P>SOLUTION: A key switch SW of a motor vehicle is turned on in a step S1. With the key switch on, voltage is applied to the inverter circuit from a preliminary charging circuit in a step S2. By this application, a line capacitor is charged, the positive voltage of the inverter circuit increases is monitored and it determined whether the voltage increases in a step S3. When the voltage of the line capacitor increases, the inverter is determined to be normal. Therefore, a line contactor is turned on in a step S4 and the inverter circuit is operated in a step S6. If shorting is made in both upper and lower elements of the main circuit, the voltage does not increase and is kept at 0 V. Therefore, it is determined to be shorted in both the upper and lower elements of the inverter circuit in a step S6. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control method for an electric vehicle (EV, forklift (FL)).
[0002]
[Prior art]
When controlling an electric vehicle, protection (failure self-diagnosis function) is performed when a main circuit (contact, main circuit element, etc.) fails. Main circuit failures mainly include open (open-phase) mode failures and short-circuit (short-circuit) mode failures. These failure detection methods will be described in connection with the circuit configuration of an electric vehicle control device provided with an inverter circuit shown in FIG. The figures are described below.
[0003]
In FIG. 12, the inverter circuit 11 includes six main circuit elements 11u to 11z such as FETs or IGBTs, and a line capacitor 12 is connected to the inverter circuit 11 in parallel.
[0004]
A series circuit of a line P1, a fuse 14, a line P2, and a line contactor 15 is connected between a line P3 of the inverter circuit 11 and a positive pole of the battery 13, and a negative pole of the battery 13 is connected to a line P7 of the inverter circuit 11. Is connected. An input terminal of a voltage detection analog input circuit 16 is connected to the line P3, and a CPU 17 is connected to an output terminal of the circuit 16, and the CPU 17 monitors the voltage of the line P3.
[0005]
Induction motors (IM) 18 are connected to lines P4 to P6 constituting the arm of the inverter circuit 11. Reference numeral 19 denotes a precharge circuit, which is connected between the line P3 of the inverter circuit 11 and the positive electrode of the battery 13.
[0006]
First, a method of checking the failure of the main circuit of the inverter circuit configured as described above will be described with respect to a short-circuit (short-circuit) check of the main circuit.
[0007]
The first check is to individually monitor the drain-source voltages of the main circuit elements (here, an example of an FET is described), and to confirm that a short circuit occurs due to a rise in the drain voltage when a gate ON command is given. This is a method of detecting (when a large current flows, the drain voltage increases due to the ON resistance of the element).
[0008]
The second check is a method of providing a current sensor (not shown) on the line P1 connected to the positive pole of the battery 13 and detecting a short circuit by detecting a large current at the time of short circuit by the current sensor. is there.
[0009]
Next, an open (open phase) check of the main circuit will be described. A first check is to provide an expensive zero-phase AC device in a wiring portion between the inverter circuit 11 and the induction motor 18 and to use the zero-phase AC device. This is a method of detecting that it is open.
[0010]
The second check is to convert and monitor the motor current detection signal (sine wave) detected by the current sensor into an effective value signal (full-wave rectification) by H / W, and to open when the detected value is smaller than the current command. It is a method of detecting that there is.
[0011]
The third check is a method of detecting that a current sensor provided on the line P1 is open from the current value of the line P1 when a check pulse (pulse voltage) is given before driving the motor.
[0012]
[Problems to be solved by the invention]
As described above, conventionally, various methods for checking whether the main circuit of the inverter circuit is short-circuited or open-circuited are performed. However, when checking for a short circuit in the main circuit of the inverter circuit, a large current flows when the gate of the FET is turned on, and it is determined that a short circuit has occurred. When the circuit is started, the damage may be further magnified.
[0013]
In addition to the above-mentioned problems, a dedicated IC for checking the drain voltage is used for each FET used in the main circuit element. There is a problem that a circuit element is required, and the configuration becomes more complicated and expensive.
[0014]
Further, in checking for an open (open phase) of the main circuit, a zero-phase AC device, a motor current detection signal conversion circuit, and the like are required, and there is a problem that the circuit configuration is more complicated and expensive.
[0015]
The present invention has been made in view of the above circumstances, and enables detection of a short circuit (short circuit) and open circuit (open phase) of a main circuit in an inverter circuit and an electric motor capable of simplifying a circuit configuration. It is an object to provide a vehicle control method.
[0016]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for controlling an electric vehicle including a battery, a pre-charging circuit, a line capacitor, a line contactor, and an inverter circuit.
After turning on the key switch of the electric vehicle, a voltage is applied from the pre-charging circuit to the inverter circuit, and it is monitored whether the positive voltage of the inverter circuit is rising. When the voltage rises, the inverter circuit is normal. It is determined that there is a voltage, and if the voltage is zero volt, it is determined that the inverter circuit is abnormal.
[0017]
According to a second aspect of the present invention, when the positive side voltage of the inverter circuit increases and the inverter circuit is determined to be normal, when the upper arm elements of the upper and lower arms constituting the inverter circuit are all turned on, the voltage becomes zero volts. Then, it is a control method for an electric vehicle, characterized in that it is determined that one of the lower arm elements of the inverter circuit is abnormal.
[0018]
According to a third aspect of the present invention, the positive side voltage of the inverter circuit rises, and if it is determined that the inverter circuit is normal, all of the upper arm elements of the upper and lower arms constituting the inverter circuit are turned on. When the arm element is turned off and the lower arm element is turned on, if the voltage is zero volt, it is determined that one of the upper arm elements is abnormal.
[0019]
A fourth invention provides a method for controlling an electric vehicle having a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
The line contactor is turned on, and while the operation of the inverter circuit is stopped, the voltage of the upper and lower arms constituting the inverter circuit is monitored. When the voltage of the upper and lower arms becomes higher than a preset voltage, one of the upper arm elements is turned off. This is a control method for an electric vehicle, characterized in that when it is determined that an abnormality has occurred and when the voltage of the upper and lower arms is zero volt, one of the lower arm elements is determined to be abnormal.
[0020]
A fifth invention provides a method for controlling an electric vehicle including a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
After obtaining a torque command value by performing a PI calculation on a deviation between the speed command value and the motor speed of the electric vehicle, when the inverter circuit is operated based on the torque command value, the torque command value is set to a preset value. In this case, the control method for an electric vehicle is characterized in that it is determined that there is no phase loss, and that the phase is determined to be missing if the phase is within the range of the phase loss determination value.
[0021]
A sixth invention provides a method for controlling an electric vehicle having a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
After obtaining the torque command value by performing a PI calculation on the deviation between the speed command value and the motor speed of the electric vehicle, when operating the inverter circuit based on the torque command value,
The current estimated value for the preset torque command value is compared with the actual current detection value of the motor, and the phase when the current value is near the peak is compared with the current value in the preset open phase detection current range. An electric vehicle control method characterized in that when the difference between the former current value and the latter current value is large, it is determined that there is no phase loss, and when the difference is small, it is determined that there is no phase loss.
[0022]
According to a seventh aspect of the present invention, in the control method for an electric vehicle according to the fifth and sixth aspects, the counter is incremented each time the phase is determined to be missing, and the phase is determined to be missing when the counter reaches a preset integrated value. This is a control method for an electric vehicle, characterized by making a determination.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart of a method for controlling an electric vehicle according to a first embodiment of the present invention. In FIG. 1, before turning on the line contactor 15 of the electric vehicle in step S1, the key switch SW of the electric vehicle is turned on. (ON).
[0024]
When the key switch is turned on, a voltage is applied from the preliminary charging circuit 19 to the inverter circuit 11 in step S2. The line capacitor 12 is charged by this voltage application, and the voltage is monitored in step S3 to see if the voltage of the line P3 (the positive voltage of the inverter circuit) has increased.
[0025]
Then, it is determined in step S3 whether the voltage of the line P3 has risen. When the voltage of the line capacitor 12 rises, the inverter circuit 11 is normal (the upper and lower arms are not short-circuited). The contactor 15 is turned on, and the inverter circuit 11 operates in step S6.
[0026]
However, when the main circuit upper and lower elements of the inverter circuit 11 are also short-circuited, the voltage of the line P3 does not increase and remains at 0 V. Therefore, it is determined to be “N” in step S3, and the process proceeds to step S6. In step S6, since it is determined that the upper and lower elements of the inverter circuit 11 are also short-circuited, a process of not turning on the line contactor 15 is performed.
[0027]
When only the upper element (eg, element 11u) of the inverter circuit 11 is short-circuited and the lower element (eg, element 11x) is normal (or open), the voltage of the line P3 remains at the charging voltage. A short cannot be detected.
[0028]
FIGS. 2, 3 (a) and 3 (b) are a flow chart and a circuit configuration explanatory diagram showing a second embodiment of the present invention. This second embodiment detects a short circuit of the upper element or the lower element of the inverter circuit 11. It is for doing.
[0029]
In the flowchart of FIG. 2, the processing of steps S1 to S3 and step S6 is the same as that of the first embodiment. If the voltage of the line P3 increases in step S3, "Y", as shown in FIG. The upper elements 11u to 11w of the inverter circuit 11 are turned on collectively in step S11.
[0030]
When the elements 11u to 11w are turned on collectively in step S11, the line P3 and the lines P4 to P6 have the same potential as shown in FIG. At this time, if all the lower elements 11x to 11z of the inverter circuit 11 are normal, the voltage of the line P3 does not change. Therefore, the voltage of the line P3 is determined to be normal "Y" in step S12. If the voltage is abnormal "N" (drops in the 0V direction), the process proceeds to step S13, where it is possible to detect that any of the lower elements 11x to 11z of the inverter circuit 11 is short-circuited.
[0031]
If it is determined in step S12 that the voltage of the line P3 is normal (lower element is normal), the upper element is temporarily turned off, and in step S14, the lower elements 11x to 11z are batched as shown in FIG. Turn ON.
[0032]
When the lower elements of the inverter circuit 11 are turned on all at once, the lines P4 to P6 become 0 V as shown in FIG.
[0033]
At this time, when all of the upper elements 11u to 11w of the inverter circuit 11 are normal, the voltage of the line P3 does not change. Therefore, the voltage of the line P3 is determined to be normal "Y" in step S15. If the voltage is abnormal “N” (drops in the 0 V direction), the process proceeds to step S16, and it is possible to detect that any of the upper elements 11u to 11w of the inverter circuit 11 is short-circuited. If it is normal "Y" in step S15, the process proceeds to step S17, and the line contactor 15 is turned on.
[0034]
By performing the processing as in the second embodiment described above, the upper element and the lower element of the inverter circuit 11 are collectively turned on, so that the short circuit of the upper and lower elements can be determined. In addition, if the second mode is used, it is possible to individually check all elements, but if this method is used, three times as much time is required, and it is not performed because it has an effect on the inverter starting time.
[0035]
FIG. 4 is a circuit configuration explanatory diagram showing a third embodiment of the present invention. In the third embodiment, the upper element or the lower element of the inverter circuit is short-circuited by monitoring the supply voltage from the inverter circuit to the motor. Is to be detected.
[0036]
In FIG. 4, a voltage detection analog input circuit 20 is provided on a line P4 for supplying a voltage from the inverter circuit 11 to the electric motor 18, and the voltage of the line P4 is monitored by the CPU 17 with the voltage detection analog input circuit 20. The circuit constant is set in advance so that the voltage value of P4 is about 1/2 of the voltage of line P3 when the element is normal.
[0037]
In the third embodiment configured as described above, if any of the upper elements 11u to 11w of the inverter circuit 11 is short-circuited, the circuit becomes the same as the second embodiment, and the voltage of the line P4 is changed to the line P3. Since the voltage becomes the same as the voltage of the element, a short circuit of the element can be detected.
[0038]
When any of the lower elements 11x to 11z of the inverter circuit 11 is short-circuited, the voltage of the line P4 becomes 0 V as in the second embodiment, so that the element short-circuit can be detected.
[0039]
If the third embodiment is used as described above, a special gate operation and a special H / W circuit are not required, and it is possible to detect whether the upper and lower elements of the inverter circuit 11 are short-circuited only by monitoring the voltage of the line P4.
[0040]
The flowchart of FIG. 5 is a flowchart showing the operation of the third embodiment. In FIG. 5, step S21 is a process in which the line contactor 15 is turned on. At this time, if the operation of the inverter circuit 11 is stopped (Y), ( In step S22, it is determined in step S23 whether the voltage of the line P4 is a normal value. If the voltage is normal (Y), the process ends.
[0041]
Then, if it is abnormal (N) in step S23, the process proceeds to step S24. It is determined in step S24 whether the voltage of the line P4 has risen. If the voltage has risen (Y), it can be detected in step S25 whether any of the upper elements is short-circuited. If not (N), the lower element has fallen in step S26. It is possible to detect whether any of the elements is short-circuited.
[0042]
Each of the above embodiments detects whether or not an element of the inverter circuit 11 is short-circuited. Next, in order to shorten the startup time of the inverter circuit, a check before startup is not performed. A fourth embodiment of the present invention for detecting whether the motor is open (during phase rotation) while the motor is rotating will be described.
[0043]
FIG. 6 is a control block diagram of an inverter according to the fourth embodiment. This control block includes three control units, a 5.0 ms control unit A, a 2.0 ms control unit B, and a 200 μs control unit C. .
[0044]
The 5.0 ms control unit A includes an accelerator input processing unit 31, a cushion processing unit 32, and a torque command limit processing unit 33.
[0045]
The 2.0 ms control unit B includes a deviation device 34 for obtaining a deviation Δω between the speed command value ω ^* output from the 5.0 ms control unit A and the speed ω of the electric motor 18, a deviation from the deviation device 34, and a torque command. A PI calculation unit 35 to which the output from the limit processing unit 33, the proportional gain Kp, and the integration gain Ki are input, calculates the torque command value Iq ^* at the output, and obtains the command value Iq ^{*. And} a slip operation unit 36 to which ^* is supplied.
[0046]
Further, in addition to the above, the 2.0 ms control unit B includes an hourly speed control processing unit 37, a second-order lag filter 38, a table 39 indicating the relationship between the hourly speed λ and the exciting inductance M, and a current obtained from the reciprocal of the exciting inductance M. It has a command unit 40, a d-axis current processing unit 41, a speed calculation unit 42, and a gain 43.
[0047]
The 200 μs control unit C includes a current control processing unit 45, a polar coordinate conversion unit 46, a coordinate conversion unit 47, a speed estimation unit 48, and an integration element 49. Note that the output of the polar coordinate conversion unit 46 is supplied to the inverter circuit 11 via a PWM conversion circuit (not shown).
[0048]
In the fourth embodiment configured as described above, the speed command value ω ^* is output from the cushion processing unit 32 of the 5.0 ms control unit A. The deviation Δω between this speed command value and the speed of the electric motor 18 is processed by the PI calculation unit 35 of the 2.0 ms control unit B using the torque command, proportionality, and integral gain, and the processing result is output as a torque command value Iq ^*. You.
[0049]
When the torque command value Iq ^* is equal to or greater than a preset value, an open (open phase) check is performed. Here, the preset torque command value Iq ^* is a value (element normal) that is sufficiently larger than the current value level (for example, several amps) for determining that the element is open.
[0050]
In FIG. 7, the sine wave of the thin line in the drawing indicates a normal motor current, the thick line indicates the phase of the motor current missing, and the hatched portion in the figure indicates the open phase detection current range. Also, in the figure, Iq ^* b1 is a current value when the torque command value Iq ^* is large, and Iq ^* b2 is a current value when the torque command value Iq ^* is small. This is a value sufficiently larger than the level, that is, a case where the element is normal.
[0051]
The current detection, the phase calculation, and the PWM control are performed every 200 μsec by the 200 μs control unit C. The current estimation value and the actual current detection with respect to the preset torque command value Iq ^* of each phase are performed every cycle. Compare values (open check).
[0052]
Normally, since the phase current is a sine wave, as shown in FIG. 8, the phase is 0 degree, 180 degrees, 360 degrees (0 degree), and the current value always becomes zero. For this reason, as shown in FIG. 8, when the open phase check phase range is wide, “current = 0” during normal operation cannot be distinguished from “current = 0” (part Z in the figure) due to element opening. The possibility that the element open check is erroneously detected increases.
[0053]
Therefore, as shown in FIG. 8, the phase at which the current value peaks (when the open-phase detection range is narrow) does not change regardless of the output frequency or the output current value. Can be predicted in advance. For this reason, if the current is compared (open check) only when the output phase is near this phase, a large difference occurs between the current value in the normal state and the current value in the open state, and accurate element open detection can be performed without erroneous detection. .
[0054]
When an element open is detected by the element open check (the current detection value is equal to or less than the open determination level), an error counter (not shown) is first incremented (once every current control cycle). After that, as shown in FIG. 9, in the motor current at the time of phase loss, the phase loss count 1, the phase loss count 2,... Are integrated by the above-mentioned counter. Identify as an error.
[0055]
The above-described element open check is performed for the U phase of the inverter circuit. However, other phases (V phase, W phase, X phase, Y phase, and Z phase) can be oscillated. Open detection of each element is possible.
[0056]
FIG. 10 is a flowchart of the open error recognition process by the 5.0 ms process. If the step S31 is a process during the operation of the inverter, it is determined in a step S32 whether the torque command value Iq ^* is larger than a set value. In S34, it is determined whether the error counter is equal to or larger than the authorized counter. If the result of this determination is that it is larger, it is determined as an open error in the processing of step S34. The error counter is reset in step S31 when the inverter is not operating in step S31 and when the value is not larger than the set value in step S32.
[0057]
FIG. 11 is a flowchart of the open error recognition processing by the 200 μs processing. The processing in steps S31 and S32 is the same as the above case. If the output phase is larger than the set value in step S32, whether the output phase is within the open check range in step S36. Judge.
[0058]
If it is within the range in step S36, the process proceeds to step S37 to determine whether the detected current is equal to or lower than the error detection level, and if not, the open counter value is updated in step S38.
[0059]
【The invention's effect】
As described above, according to the present invention, it is possible to detect a short circuit and an open circuit of a main circuit in an inverter circuit without using a special H / W, and to simplify the circuit configuration. Further, it is possible to detect even if the inverter start delay time is shortened (after starting the contactor) after the short / open check time is minimized, and that the element open can be detected during the inverter operation.
[Brief description of the drawings]
FIG. 1 is a flowchart of an electric vehicle control method according to a first embodiment of the present invention.
FIG. 2 is a flowchart of a control method according to a second embodiment of the present invention.
FIG. 3 is an explanatory diagram of a circuit configuration showing a second embodiment.
FIG. 4 is an explanatory diagram of a circuit configuration of an electric vehicle control device according to a third embodiment of the present invention.
FIG. 5 is a flowchart showing the operation of the third embodiment.
FIG. 6 is a control block diagram of an inverter according to a fourth embodiment of the present invention.
FIG. 7 is a motor current waveform chart at the time of phase loss for describing the operation of the fourth embodiment.
FIG. 8 is a motor current waveform diagram at the time of phase loss for describing the operation of the fourth embodiment.
FIG. 9 is a motor current waveform diagram at the time of phase loss for describing the operation of the fourth embodiment.
FIG. 10 is a flowchart showing open error recognition processing by 5.0 ms processing;
FIG. 11 is a flowchart showing open gamma detection processing by 200 μs processing.
FIG. 12 is an explanatory diagram of a circuit configuration of an electric vehicle control device including an inverter circuit.
[Explanation of symbols]
11 inverter circuit 12 line capacitor 13 battery 15 line contactor 16 voltage detection analog input circuit 17 CPU
18 motor 19 pre-charge circuit 20 voltage detection analog input circuit A 5.0 ms control unit B 2.0 ms control unit C 200 μs control unit

Claims (7)

In a control method of an electric vehicle having a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
After turning on the key switch of the electric vehicle, a voltage is applied from the pre-charging circuit to the inverter circuit, and it is monitored whether the positive voltage of the inverter circuit is rising. When the voltage rises, the inverter circuit is normal. A control method for the electric vehicle, wherein it is determined that there is a voltage, and if the voltage is zero volt, the inverter circuit is determined to be abnormal. If the positive side voltage of the inverter circuit rises and it is determined that the inverter circuit is normal, when all the upper arm elements of the upper and lower arms constituting the inverter circuit are turned on, if the voltage becomes zero volts, the inverter circuit 2. The control method for an electric vehicle according to claim 1, wherein it is determined that one of the lower arm elements is abnormal. When the positive side voltage of the inverter circuit rises and the inverter circuit is determined to be normal, when all the upper arm elements of the upper and lower arms constituting the inverter circuit are turned on, if the voltage is normal, the upper arm element is turned off. 2. The control method for an electric vehicle according to claim 1, wherein when the lower arm element is turned on, if the voltage is zero volt, it is determined that one of the upper arm elements is abnormal. In a control method of an electric vehicle having a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
The line contactor is turned on, and while the operation of the inverter circuit is stopped, the voltage of the upper and lower arms constituting the inverter circuit is monitored. When the voltage of the upper and lower arms becomes higher than a preset voltage, one of the upper arm elements is turned off. A method for controlling an electric vehicle, comprising determining that one of the lower arm elements is abnormal when the voltage of the upper and lower arms is determined to be abnormal and the voltage of the upper and lower arms is zero volt. In a control method of an electric vehicle having a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
After obtaining a torque command value by performing a PI calculation on a deviation between the speed command value and the motor speed of the electric vehicle, when the inverter circuit is operated based on the torque command value, the torque command value is set to a preset value. In the above, a control method for an electric vehicle is characterized in that it is determined that there is no phase loss, and that the phase is determined to be missing if the phase is within the range of the phase loss determination value. In a control method of an electric vehicle having a battery, a precharge circuit, a line capacitor, a line contactor, and an inverter circuit,
After obtaining the torque command value by performing a PI calculation on the deviation between the speed command value and the motor speed of the electric vehicle, when operating the inverter circuit based on the torque command value,
The current estimated value for the preset torque command value is compared with the actual current detection value of the motor, and the phase when the current value is near the peak is compared with the current value in the preset open phase detection current range. A control method for an electric vehicle, characterized in that when the difference between the former current value and the latter current value is large, it is determined that there is no phase loss, and when the difference is small, it is determined that there is no phase loss. 7. The control method for an electric vehicle according to claim 5, wherein the counter is incremented each time the phase is determined to be missing, and the phase is determined to be missing when the counter reaches a preset integrated value. Control method for an electric vehicle.

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