JPH04251503A - Electric car control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to an electric vehicle that uses an induction motor for propulsion and is driven by a power converter that outputs polyphase alternating current power of variable voltage and variable frequency. In particular, the present invention relates to a control device for an electric vehicle that controls a braking range from a regenerative braking range to a reverse-phase braking range.

0002

[Prior Art] In recent years, electric vehicles have been developed that use an induction motor for propulsion and control the motor from the power running range to the braking range using a power converter that outputs polyphase AC power of variable voltage and frequency. Although it is becoming more common, in recent years,
In order to obtain sufficient braking force up to extremely low speeds, various electric vehicles have been proposed that use anti-phase braking in combination with braking, and an example of a control device for such an electric vehicle is shown in FIG.

The example shown in FIG. 4 shows a variable voltage/variable frequency (
Using an example of a control device for an electric vehicle that uses an inverter (VVVF) as a power converter, the control operation during normal braking will be explained below. A brake force command is input to the slip frequency pattern generator 1, and in response to the brake force command, a slip frequency command fs that changes according to a predetermined pattern is generated. Deviation from frequency fr (fr-f
s) is obtained as the inverter frequency fINV.

The inverter frequency fI thus generated
NV is input to the pulse mode control section 6, where various pulse modes are selected, and then the PWM pulse generation section 8
is supplied to

On the other hand, the brake force command is also input to the V/F pattern generating section 2, which generates a V/F pattern value corresponding to the brake force command. Therefore, the modulation degree calculating section 7 uses this V/F pattern value and the inverter frequency f.
INV is input, the modulation degree necessary to generate a predetermined output voltage V is generated as a result of these multiplications, and this is
It is supplied to the WM pulse generator 8.

Therefore, this PWM pulse generating section 8 uses the above-mentioned inverter frequency fINV, the pulse mode supplied from the pulse mode control section 6, and the modulation degree calculation section 7.
A PWM pulse is generated based on the modulation degree supplied from the gate pulse generating section 1 via the phase sequential switching section 9.
0 so that the gate pulse is supplied to the switching element of the VVVF inverter (not shown),
As a result, AC output having the inverter frequency fINV and voltage V necessary for generating torque (regenerative braking torque) corresponding to the brake command from the induction motor for electric vehicle propulsion is supplied from the VVVF inverter to the induction motor. We will make sure that it is done.

[0007] In this way, by generating regenerative braking torque corresponding to the brake command, a predetermined regenerative braking force is applied to the electric vehicle, and as a result, the speed of the electric vehicle decreases. As the deviation (fr
Since the inverter frequency fINV given by -fs) also decreases, it eventually becomes 0 Hz.

On the other hand, the inverter frequency fINV is 0Hz
Since it is also input to the detection unit 5, the inverter frequency f
When INV reaches 0 Hz, a switching signal is generated from the 0 Hz detection section 5, and the phase sequential switching section 9 is thereby operated. As a result, the phase order of the PWM pulses supplied from the PWM pulse generator 8 to the gate pulse generator 10 is switched to the opposite direction, and as a result, the AC power supplied from the inverter to the induction motor for propulsion of the electric vehicle is changed. The phase sequence will also be reversed and the brake will be in reverse phase braking mode.
Sufficient braking force can be obtained up to almost zero speed.

[0009] This type of technology that uses anti-phase braking in combination with braking in order to obtain sufficient braking force up to very low speeds is considered to be particularly effective in the case of linear motor propulsion electric vehicles. Related technologies for this purpose include, for example, "Science of Electric Vehicles" 1989, Vol. 1.40, No.
．． 10 "Research and development of linear motor-driven vehicles for Tokyo Metropolitan Subway Line 12 [3]", and further related to the present invention are JP-A-58-15402 and JP-A-2 Examples include various publications such as No.-17805.

0010

SUMMARY OF THE INVENTION The above-mentioned prior art does not take into account the reduction in the degree of modulation when the inverter frequency approaches 0 Hz, and has a problem in ensuring a stable braking force. In other words, when applying anti-phase braking, as described above, when the inverter frequency decreases from the regenerative braking state and reaches 0Hz, the phase order is switched, and then the inverter frequency is gradually increased (inverter However, in the conventional technology, when the inverter frequency is near 0Hz, the modulation degree that controls the inverter output voltage also becomes a value close to zero, so the induction motor Since no voltage is applied to the motor, almost no braking torque can actually be obtained from the electric motor, and as a result, stable braking force cannot be secured in the extremely low speed range.

An object of the present invention is to provide a control device for an electric vehicle that is capable of sufficiently stable braking operation from the regenerative braking region at low speeds to the reverse phase braking region, even at very low speeds where the speed is close to zero. It is about providing.

0012

[Means for Solving the Problem] In order to achieve the above object, a modulation degree control system for reverse phase braking control, which is different from a modulation degree control system for normal regenerative braking control, is provided in the control section of the inverter, These are switched just before the inverter frequency reaches 0 Hz.

[0013]

[Operation] The modulation degree control system for inverter regenerative braking control controls the ratio of the inverter frequency and inverter output voltage, that is, V/F, to a predetermined constant value, thereby achieving a predetermined regenerative braking torque. Work to get what you want.

The modulation degree control system for anti-phase braking control includes a dedicated inverter for use in calculating the modulation degree in a predetermined range including the transition point from regenerative braking to anti-phase braking in the low speed region of the inverter. The frequency is created using a pattern different from that of the modulation degree control system for regenerative braking control. This dedicated inverter frequency is limited to a predetermined constant value, such as 1.5Hz, when the original inverter frequency is near 0Hz, and even when it is in the opposite phase braking region to the regenerative braking region before and after it. The frequency is set higher than the original inverter frequency.

Therefore, when the original inverter frequency approaches 0Hz, by switching from the modulation degree control system for regenerative braking control to the modulation degree control system for anti-phase braking control, the inverter output in this region can be adjusted. Unnecessary drops in voltage are suppressed, making it possible to maintain stable braking torque.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for an electric vehicle according to the present invention will be explained in detail below with reference to the illustrated embodiments.

First, FIG. 1 shows an embodiment of the present invention. In FIG. 1, 30 is a reverse phase brake pattern generator;
is a 5Hz detection part, and 50 is a changeover switch part,
Other components are the same as the conventional example shown in FIG.

The reverse phase brake pattern generator 30 inputs both the inverter frequency fINV (hereinafter also referred to as the original inverter frequency) and the detection signal from the 0Hz detection section 5, and generates a predetermined pattern, that is, as shown in FIG. According to the characteristics shown by the solid line, a dedicated inverter frequency (herein referred to as the second inverter frequency fINV2) is used to calculate the modulation degree at the time of transition from regenerative braking to anti-phase braking in the low speed region of the inverter. ). In FIG. 2, the broken line represents the characteristics when the original inverter frequency is used as is, and as is clear from comparison with this, the characteristics of the negative phase brake pattern generator 3 are in the positive phase region. In other words, in the regenerative braking state region, the inverter frequency fINV decreases, and when it reaches approximately 2.5Hz, it departs upward from the characteristic indicated by the broken line, and below approximately 1.0Hz, the inverter frequency fINV decreases to the second inverter frequency fINV.
2 is clamped to a constant value of 1.5Hz, and this 1
．． Starting from a clamp value of 5 Hz, the characteristics match the dashed line up to 5 Hz.

The 5Hz detection unit 40 detects the inverter frequency fI
It functions to generate a switching signal s for operating the above-mentioned changeover switch section 50 only when the NV is input and enters a region of 5 Hz or less.

The changeover switch section 50 performs a switching operation in accordance with the switching signal s supplied from the 5Hz detection section 40, and changes the input to the modulation factor calculation section 7 to the original inverter frequency fIN.
It functions to switch from V to the second inverter frequency fINV2, and specifically, only when the switching signal s is supplied from the 5Hz detection section 40, as shown in FIG. The configuration is such that the inverter frequency fINV2 is selected.

Next, the operation of the embodiment shown in FIG. 1 will be explained. First, as in the case of the conventional example shown in FIG. Since the switching signal s is not generated from the detection section 40, the changeover switch section 50 is switched to the right side opposite to that shown in the figure.
INV is being input. Therefore, at this time, the embodiment shown in FIG. 1 is in the same configuration as the conventional example shown in FIG. regenerative braking torque) is generated, and a deceleration driving control operation by regenerative braking is obtained.

[0022] As a result of such deceleration operation, the speed of the electric vehicle decreases, and eventually the inverter frequency fINV
Assuming that the frequency has decreased to 5Hz, the switching signal s is generated from the 5Hz detection unit 40, the changeover switch unit 50 is switched to the left as shown in the figure, and from this point on, the modulation degree calculation unit 7 The inverter frequency f that had been input until now
In place of INV, the second inverter frequency f that changes according to the characteristics shown in FIG.
INV2 is input, and the modulation degree calculated based on this is P.
The voltage is supplied to the WM pulse generator 8, thereby controlling the voltage supplied from the inverter to the induction motor.

As a result, as is clear from FIG. 2, in the embodiment of FIG. 1, when the vehicle speed decreases under braking and the inverter frequency fINV decreases to about 2.5 Hz, the inverter frequency fINV becomes The second inverter frequency fIN is different and takes a higher frequency.
The modulation degree is calculated by V2, and therefore the inverter frequency fIN of 1.5Hz even near zero speed.
The modulation degree corresponding to V is maintained, and the speed eventually becomes zero, and along with the phase sequence switching based on the detection signal from the 0Hz detection unit 5, the torque is reliably transferred from the motor from the regenerative braking region, that is, from the normal phase region to the negative phase braking region. (in the opposite direction), ensuring sufficient stable braking force even in the extremely low speed range.

Next, another embodiment of the present invention is shown in FIG. The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. is provided, and the changeover switch section 5
0 is only that the output of the V/F pattern generation section 2 and the output of this negative phase brake modulation rate pattern generation section 60 are switched and inputted to the modulation degree calculation section 7,
The other configurations are the same.

The negative phase brake modulation rate pattern generator 60 has a different modulation rate pattern from the V/F pattern generator 2, and thereby generates a higher modulation rate than the output of the V/F pattern generator 2. is configured to do so.

Therefore, even in the embodiment shown in FIG. 3, the induction motor for running the vehicle is capable of generating the torque necessary for regenerative braking and anti-phase braking even in the extremely low speed region where the vehicle speed is close to zero. Since sufficient terminal voltage is ensured to enable
Sufficient and stable braking force can be ensured even at extremely low speeds.

By the way, although not specifically explained in the above embodiment, the present invention may be applied to an electric vehicle using a linear induction motor propulsion system. In this case, since the above-mentioned slip frequency is large, It is also more effective, and the braking range can be greatly expanded from the regenerative braking range to the reverse phase braking range.

Furthermore, although the above embodiments have been explained using open-loop control, the present invention may also be implemented using a feedback control system using motor current detection, which is common for controlling a normal rotary induction motor. Needless to say.

[0029]

According to the present invention, when the vehicle speed is below a predetermined value, the degree of modulation of the VVVF inverter is changed, so that braking can be applied from a low speed regenerative braking region to an extremely low speed reverse phase braking region. It is now possible to apply the brakes smoothly and while maintaining the necessary braking force.
As a result, the braking control area by the brake can be sufficiently widened, so the range in which the air brake is used is reduced, and wear of the brake shoes and the like is reduced, so that effects such as improved maintainability can be obtained.

[Brief explanation of the drawing]

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

FIG. 2 is a characteristic diagram showing the characteristics of a negative phase brake pattern generating section in the present invention.

FIG. 3 is a block diagram showing another embodiment of the electric vehicle control device according to the present invention.

FIG. 4 is a block diagram showing a conventional example of a control device for an electric vehicle.

[Explanation of symbols]

1 Slip frequency pattern generation section 2 V/F pattern generation section 5 0Hz detection part 6 Pulse mode control section 7 Modulation degree calculation section 8 PWM pulse generation section 9 Phase sequence switching section 10 Gate pulse generation section 30　Reverse phase brake pattern generation part 40 5Hz detection part 50 Changeover switch section

Claims (4)

[Claims] Claim 1: A power converter that outputs polyphase AC power of variable voltage and variable frequency is used to supply power to an electric motor for propulsion of an electric vehicle, and a predetermined pattern of polyphase AC power output from the power converter is used. In the control device for an electric vehicle, the operation of the motor for propulsion of the electric vehicle is controlled by voltage-frequency related control and phase-sequence switching control of the multi-phase AC power. means for detecting a predetermined range of operation region that includes a control region approximately in the center thereof, and detects the pattern for the related control of the voltage and frequency of the polyphase AC power when the control region is within the predetermined range of operation region. A control device for an electric vehicle, characterized in that it is configured to switch to a pattern different from a predetermined pattern. 2. In the invention according to claim 1, the means for generating a pattern different from the predetermined pattern is configured to receive an output frequency of the power converter as an input and generate a pattern as a function of the output frequency. An electric car control device characterized by: 3. In the invention according to claim 1, the means for generating a pattern different from the predetermined pattern is configured to receive a brake force command of an electric vehicle as an input and generate a pattern as a function of the command. An electric car control device characterized by: 4. A control device for an electric vehicle according to claim 1, wherein the electric motor for propulsion of the electric vehicle is a ground secondary conductor type linear induction motor.