JPH0452682B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a slipping/slipping detection device for an electric vehicle,
In particular, the present invention relates to a device for detecting slipping and skidding in an electric vehicle that supplies power to a plurality of induction motors using a variable voltage variable frequency inverter.

[Technical background of the invention]

In a typical electric vehicle, constant torque control of the electric motor is desired because acceleration and deceleration must be performed quickly. When constant torque control of an induction motor is performed using an inverter, the slip frequency s of the induction motor is kept constant by controlling the V/ratio of the output voltage V and output frequency of the inverter to a constant value.

FIG. 5 shows a typical system block. That is, DC power is supplied from the overhead wire 1 through the pantograph 2, smoothed through the reactor 3 and capacitor 4 of the filter, and is used as the input DC power to the inverter 5. Inverter 5
Then, the power is converted to DC/3-phase AC, and the variable voltage variable frequency power according to the vehicle speed is applied to the induction motors 6 and 7.
supply to.

These electric motors 6 and 7 are provided with rotation speed detectors 8 and 9, and rotation speed signals PG1 and PG2 are obtained, and these signals are given to a rotation frequency calculation section 10 to determine the rotation speed of the electric motors 6 and 7. Rotation frequency according to
R1 and R2 are calculated. This calculation result is given to the rotational frequency selection unit 11, which selects MIN (R1, R2) during power running acceleration of the electric vehicle and MAX during regenerative deceleration.
Select (R1, R2) to obtain the reference rotation frequency R.

On the other hand, the torque command value Tc for the electric motors 6 and 7 is given to the input current pattern generating section 12 of the electric motor to form a current pattern Ip. This current pattern Ip
is given to the slip frequency setting pattern generating section 13 to form a slip frequency pattern sp.

Further, the current pattern Ip is detected by the motor input current detector 14. This detection signal is the current effective value obtained by calculation processing in the current effective value calculation section 17.
It is compared with IM and the deviation between the two is extracted.
This deviation is then given to the amplifying section 15 to obtain the corrected slip frequency Δs.

This allows the inverter output frequency during power running acceleration to
INV is INV=R+sp+ΔS...(1), and during regenerative deceleration, INV=R-(sp+ΔS)...(2).

This inverter frequency INV is given to the phase shifter 16, and as shown in FIG. 6, the current flow rate of the inverter is controlled so that the output voltage V of the inverter 5 becomes constant V/INV according to the inverter output frequency INV. be exposed.

Here, since the induction motor has a shunt characteristic, if the input power frequency is kept constant, even if the wheels are spinning, the torque will decrease as the speed approaches the synchronous speed.
It has the property of being easy to re-stick.

[Problems with background technology]

However, in the idling/slipping detection device shown in FIG. 5, for example, when the drive shafts of the electric motors 6 and 7 both idle and the rotational speed increases, the inverter's output frequency INV follows and increases, so that the inverter output voltage also increases so that it becomes V/constant. As a result, electric motors 6, 7
The torque does not decrease and the engine spins even more violently. For this reason, there is a need to detect slippage by some method and promptly re-adhesion.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and
An object of the present invention is to provide a slipping/skidding detection device for an electric vehicle that can promptly detect slipping/sliding without malfunction in an electric vehicle that drives a plurality of induction motors with a variable voltage variable frequency inverter.

[Summary of the invention]

In order to achieve this objective, the present invention calculates the average value of the rotational speed every predetermined time, detects idle rotation when the change in the average value of the rotational speed every predetermined time exceeds a first predetermined value, and This invention provides a slipping/sliding detection device for an electric vehicle that detects skidding when the value falls below a predetermined value.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows an embodiment of the present invention. This embodiment has two pulse signal processing circuits 20 and 30, both of the same configuration, for processing pulse signals PG1 and PG2 from two pulse generators, respectively. The processing results of these two pulse signal processing circuits 20 and 30 are then processed as data.
The signals are given to the microprocessor 29 as CH1, CH2, M1n, M2n, TM1n, and TM2n, and are used to detect whether the electric car is idling or skidding.

Here, the circuit 20 will be explained using two pulse signal processing circuits 20 and 30 having the same configuration as representatives, and the relationship between the circuit 20 and the microprocessor 29 will be explained.

The pulse signal processing circuit 20 receives the pulse signal PG1 from one of the pulse generators through the one-shot multivibrator 21. The one-shot multivibrator 21 receives the received pulse signal.
After shaping PG1, it is applied to the digital input section 22.

The digital input section 22 converts the rising edge of the signal from the one-shot multivibrator 21 into a synchronization signal.
It is detected as CH1 and provided to the microprocessor 29.

Furthermore, the pulse signal that is the output signal of the one-shot multivibrator 21 is transmitted to another one-shot multivibrator 24 for on-delay.
given to. The pulse signal subjected to on-delay by the one-shot multivibrator 24 is applied to a counter 23 capable of reading out count values and preset loading, and the number M1n of pulse signals PG1 from the pulse generator is counted.

And one-shot multivibrator 24
The output signal is applied to another counter 27 which can read the count value and load a preset, and the pulse signal generation period TM1n is measured based on the clock signal from the clock generator 25.

This measurement result is given to the microprocessor 29.

FIG. 2 shows how the microprocessor 29 performs the function of detecting wheel slipping and skidding of the electric vehicle based on the data CH1, M1n, TM1n and CH2, M2n, TM2n input to the microprocessor 29 in FIG. This is a circuit representation using a block diagram.

Here, CH1 and CH2 given as input are
This is a pulse rising signal indicating the rise of the pulse signal PG from the pulse generator, M1n and M2n are the number of pulses, and TM1n and TM2n are the pulse intervals (periods). In addition, P/B is a signal indicating whether the electric vehicle is in power running state or regeneration state, MP is the detection level of slipping during power running, MB is the detection level of skidding during regeneration, and Ts
indicates the detection period for slipping and skidding, and WSD
1. WSD2 shows the detection signals of slipping and skidding, respectively.

Of the circuit elements that respond to these inputs, 41 and 51 are average value calculation units that calculate the average value of the motor rotation speed during the detection period Ts, and 42 and 5
2 is a sample hold circuit that takes out a sampling value for each detection period Ts, and 43 and 53 are comparison units that compare the change in motor rotation speed for each detection period Ts with the slip detection level MP or the skidding detection level MB. Yes, and 60 is the detection level MP of slippage during power running according to the electric vehicle status signal P/B.
This is a switch that switches between the detection level MB of skidding during regeneration and the detection level MB of skidding during regeneration.

In the circuit shown in FIG. 2, the pulse signal processing circuit 2
Perform calculations according to the signals from 0 and 30. Looking at the signals from the pulse signal processing circuit 20, the number of pulses M1n from the counter 23 from the time when the pulse rising signal CH1 is given,
Then, the average rotational speed of the electric motor is calculated using the pulse number TM1n from the counter 27.

FIG. 3 is a timing chart for explaining the operation of the circuit shown in FIGS. 1 and 2.
The operation will be explained below based on the diagram.

In FIG. 3, the sampling time TS is from time t1 to t2. When a motor rotational speed signal as shown in the figure is given in relation to this time TS, the output of the one-shot multivibrator 21 is input to the microprocessor 29 via the digital input section 22 as a latch signal for calculation. .

At the same time, at time t11, which is delayed by ΔtA via the one-shot multivibrator 24, the counter 27 is preset and starts counting by the clock output from the clock generator 25. Then, at the next output time t12 of the one-shot multivibrator 21, the microprocessor 2
9 is given the calculation latch signal CH1, the count value TM11 of the counter 27 and the count value M11 of the counter 23 (number of PG pulses)
is read into the microprocessor 29.

This operation is performed over the sampling time TS from time t1 to t2, and n pieces of data are read into the microprocessor 29. In the microprocessor 29, the average rotational speed calculating section 41 calculates the rising signal CH1, the number of pulses M1n, and the pulse interval TM1n.
Accordingly, the following calculation is performed: FM1=k・TM11+...TM1n/M1n+1-M11...(3) The average rotational speed M of the motor is determined. Then, at time t2, the next sampling period starts, and at this time, the average rotational speed M of the motor is sampled and held in the sample and hold circuit 42.

The calculation of equation (3) above is also performed from time t1 to t3. Then, at time t3 [FM1 (N) - FM1 (0)]
and [FMp (during power running), FMB (during regeneration)] are compared in a comparison section 43. Here, FM1 (N) is from t2 to t3
The average rotational speed calculation value, FM1 (0) is the average rotational speed calculation value from t1 to t2. If FM1 (N) - FM1 (0) > FMP, then the wheel connected to the electric motor 6 is spinning, and if FM1 (N) - FM1 (0) < FMB, the wheel connected to the electric motor 6 is spinning. Detects that the wheels are skidding.

Similarly, the detection circuit 30 calculates the PG2 signal and detects whether the wheels connected to the electric motor 7 are spinning or skidding.

In this way, the average rotation speed of the motor within the sampling time TS is calculated for each sampling time Ts,
Spin and skid of the electric vehicle's wheels is detected based on the average rotational speed change rate for each sampling time.

FIG. 4 shows another embodiment of the present invention, in which vehicle speed is added to the determination condition. That is, the reference rotational frequency R is given to the vehicle speed determination section 61 and compared with a predetermined value C, and when the vehicle speed is low, the sampling time is set by the selection switch 62.
TS1, and when the vehicle speed is higher than C, the sampling time is TS2 (TS1>TS2).

This is because in Figure 3, when the vehicle speed is low, the number of pulses input within the sampling time TS is small, and the error in the average rotation speed calculation value is larger than when the vehicle speed is high.
This is designed to increase Ts.

〔Effect of the invention〕

As described above, the present invention calculates the average value of the wheel rotation speed at each predetermined time, compares the change in the above average value at each predetermined time with the slip detection level or the skid detection level, and when the wheel rotation speed is greater than the slip detection level, is determined to be slipping, and when it is smaller than the skidding detection level, it is determined to be skidding, so that it is possible to accurately and quickly detect when the wheels of the electric vehicle are spinning or skidding.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention, FIG. 2 is a block diagram showing the main structure of the embodiment of FIG. 1, and FIG. A timing chart for explaining the operation of the circuit; FIG. 4 is an explanatory diagram showing the configuration of another embodiment of the present invention; FIG.
FIG. 6 is an explanatory diagram showing the configuration of an electric vehicle control system to which the present invention is applied, and FIG. 6 is a diagram showing control characteristics of the inverter in the system of FIG. 5. 5... Inverter, 6, 7... Induction motor, 2
1, 24...One-shot multivibrator,
22... Digital input section, 23, 27... Counter, 25, 28... Clock generator, 4
1, 51...Average rotation speed calculation section, 60, 62...
Changeover switch, 61...vehicle speed determination section.

Claims (1)

[Claims] 1. A plurality of rotation speed detection means 8, 9 for detecting the respective rotation speeds of the plurality of induction motors 6, 7 for driving an electric vehicle supplied with power from the variable voltage variable frequency inverter 5.
Obtaining the respective rotational speeds of the plurality of induction motors from these rotational speed detection means and calculating the average value at predetermined time intervals,
calculation storage means 41 for storing this average value and outputting the stored average value at each predetermined time;
51, 42, 52, a change detecting means for receiving an output from the calculation storage means at the predetermined time intervals and detecting a change in the output; a slip level during power running and a skidding level during regeneration of the electric vehicle; a level signal output means for forming and outputting signals FMP and FMB each having a predetermined value corresponding to the electric vehicle; a switching means 60 that performs a switching operation to take out a slipping level signal during power running and a sliding level signal during regeneration during regeneration; A slipping/sliding detection device for an electric vehicle, comprising comparing means 43, 53 for comparing the level signals of the electric vehicle and outputting the comparison results. 2. In the device according to claim 1, the slipping/slipping detection device includes a speed determining means 61 for detecting the speed of the electric vehicle.
and means 62 for selecting a larger predetermined time when the speed is low and a smaller predetermined time when the speed is high, according to the output of the speed detecting means.