JPH01268410A - Dc series motor controller for electric vehicle - Google Patents

Abstract

PURPOSE:To obtain brake force proportional to the operating amount of accelerator, by performing voltage control under normal traveling and performing current control under plugging. CONSTITUTION:Contacts 31b1, 31b2 are turned ON under normal traveling. Consequently, a PWM modulation circuit 14 produces a PWM signal corresponding to an accelerator voltage which is proportional to the operating amount of accelerator fed from a voltage divider 10. When the armature current exceeds over the voltage of a reference voltage generating power source 30, a differential amplifier circuit 9 blocks application of voltage onto the PWM modulation circuit 14. On the other hand, contacts 31a1, 31a2 are turned ON under plugging. Consequently, voltage is fed from the reference voltage generating power source 30 to the PWM modulation circuit 14, and accelerator voltage is fed to the differential amplifier circuit 9. By such arrangement, plugging can be performed smoothly with no impact.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a control device for a DC series motor for an electric vehicle.

Prior Art and Problems of the Invention There are two methods for controlling DC series motors for electric vehicles: one is a current control method in which the amount of accelerator operation is proportional to the current value of the motor, and the other is a current control method in which the amount of accelerator operation is proportional to the motor voltage value (chopper circuit current flow). There is a voltage control method that is proportional to

In the case of the current control method, the amount of accelerator operation is proportional to the amount of acceleration, and it is difficult to maintain the vehicle speed constant. However, it has the advantage that smooth acceleration characteristics and smooth plugging characteristics can be obtained.

In the case of the voltage control method, since a speed proportional to the amount of accelerator operation is obtained, it is easy to maintain the vehicle speed constant. However, during plugging, it is not possible to obtain a braking force proportional to the accelerator, so even if it is desired to stop the vehicle with a small braking force, the braking force cannot be controlled and there is a drawback that a shock occurs. However, even if the voltage control method is used, there is a current limiting circuit that limits the maximum current, so if the amount of accelerator operation is large,
The current limiting circuit operates and the same characteristics as the current limiting method can be obtained.

In the voltage control system, a method has been developed in which the conduction rate of the chopper circuit is reduced to a fraction of that during normal running only during plugging in order to soften the impact during plugging. However, this method has the drawback that when the vehicle starts climbing in the middle of a slope, even if the vehicle backs up a little, it enters plugging mode, resulting in insufficient braking force and climbing force, causing the vehicle to slide down and not be able to climb the hill. Also,
Even in this case, it is not possible to obtain a braking force proportional to the amount of accelerator operation.

An object of the present invention is to provide a control device for a DC series motor for an electric vehicle, which has characteristics of a voltage control method during normal running and characteristics of a current control method during plugging.

In order to understand the present invention, a specific example of a current control method and a specific example of a voltage control method will be explained.

FIG. 3 shows a current control type motor control circuit developed by the applicant. A forward and reverse drive circuit (2) is connected in series to the armature (1) of the series-wound DC motor.
This series circuit is connected in parallel to the storage battery (3).

The forward/reverse drive circuit (2) includes a forward drive circuit consisting of a series circuit of a forward field winding (4r) and a forward power transistor (5f), and a reverse field winding (4r) and a reverse drive circuit. It is composed of a reverse drive circuit consisting of a series circuit with a power transistor (5r). The forward drive circuit and the reverse drive circuit are connected in parallel.

A plugging diode (6) is connected in parallel to the armature (1). Armature (1) and forward field winding (
A forward flywheel diode (7r) is connected in parallel to the series circuit with '41'). Armature (1
) and the reverse field winding (4r), a reverse flywheel diode (7r) is connected in parallel.

The armature circuit is equipped with an armature current (motor current) detector (8
) is provided. This detector (8) consists of, for example, a current shunt, and the voltage Vf dropped across the resistance of the current shunt is used as a detection signal. This detection signal Vf is sent to the inverting input terminal of the differential amplifier circuit (9) via a resistor R3. Positive feedback is applied to the differential amplifier circuit (9) via a feedback resistor R2.

A voltage divider (1) whose partial pressure ratio m is controlled according to the accelerator operation
0) (accelerator voltage) Vd is sent to the non-inverting input terminal of the differential amplifier circuit (9) via the resistor R1. The accelerator voltage Vd is proportional to the accelerator operation amount.

The output (voltage Va) of the differential amplifier circuit (9) is sent to the transistor drive circuit (11). The output terminal of the drive circuit (11) is connected to the base of the forward power transistor (5f) via the forward A contact (22a), and is connected to the base of the forward power transistor (5f) via the reverse A contact (23a). Connected to the base of the power transistor (5r). The forward a contact (22a) is the forward/reverse switching operation switch (
21) is switched to the forward side, and the forward relay (22
) is activated. Reverse a contact (
23a) is turned on when the forward/reverse switching operation switch (21) is switched to reverse and the reverse relay (23) is activated.

The power transistor (5f) or (5r) is controlled on and off according to the output of the differential amplifier circuit (9), thereby driving the DC motor in forward or reverse rotation.

The input voltage of the voltage divider (10) is input to the Ve1 differential amplifier circuit (9).
The input voltage of the non-inverting input terminal of the VB1 current detector (8)
The output voltage of the differential amplifier circuit (9) is Vf, the input voltage of the inverting input terminal of the differential amplifier circuit (9) is Vc, and the output voltage of the differential amplifier circuit (9) is Vf.
Let it be a.

a, When Vb<Vc, the following relationship holds true.

Vd-m -Ve Vb-Vd Vc-Vf Va-Q b, When Vb>Vc, the following relationship holds true. However, the resistance of the voltage divider (10) is assumed to be much smaller than R1.

Vd-m・Ve Vb-Vd+ (Va-Vd) ・ (R1/ (R1
+R2)) Vc-Vf Va-Vs (constant voltage) FIG. 4 shows the waveforms of vb and Vf, and FIG. 5 shows the waveform of Va. In FIG. 4, the rise characteristics of Vf are determined by the inductance of the DC motor, the load, and the voltage vb. The falling curve of Vf is
The current flowing through the flywheel diode (7r) or (7r) is shown.

As can be seen from FIGS. 4 and 5, in the current@one-way type motor control circuit, the maximum current value flowing through the DC motor, that is, the acceleration performance, is controlled by operating the accelerator.

FIG. 6 shows the characteristics of the DC motor obtained by the above-mentioned current control method, and shows the relationship between the rotational speed N and the generated torque T.

Curve A (a-d) shows the static characteristic curve of a DC motor. Torque T1 indicates the load torque during steady running, and speed N1 indicates the speed corresponding to T1. When the accelerator operation amount is a relatively small operation ff1sL, the characteristics of the DC motor are those shown by the curve g-c-d. When the accelerator operation amount is a relatively large operation amount SH, the characteristics of the DC motor are as shown by the curve e-a-d. The accelerator operation amount is the intermediate value S between SH and SL
When M, the characteristics of the DC motor are curve f'-b
The characteristic is indicated by -d.

As can be seen from Figure 6, in the above current control method, the accelerator operation amount acts to control torque, so it has a characteristic of controlling acceleration, and it is difficult to control the vehicle speed to an intermediate speed smaller than speed N1. It is. For example, even if the accelerator operation amount is maintained at a relatively small operation amount SL, the acceleration will be small but the vehicle speed will reach the speed N1. In this way, with the current control method, it is difficult to control the vehicle speed, but at the time of plugging, a braking force corresponding to the accelerator operation amount can be obtained, so that smooth plugging can be performed.

FIG. 7 shows a voltage control type motor control circuit. In FIG. 7, the same parts as in FIG. 3 are given the same reference numerals and their explanations will be omitted.

A voltage divider (10
) is sent to the PWM modulation circuit (chopper control circuit) (14) as a speed command signal. The PWM signal output from the PWM modulation circuit (14) is sent to the transistor drive circuit. The input terminal of the PWM modulation circuit (14) is connected to the PWM signal cutoff switching transistor (14).
3) is grounded via.

The detection signal of the armature current detector (8) is sent via a resistor R1 to a non-inverting input terminal of a differential amplifier circuit (9) to which positive feedback is applied via a feedback resistor R2. Differential amplifier circuit (
The inverting input terminal of 9) is connected to the resistor R3 from the power supply (12).
A reference voltage for current limiting is sent via. The differential amplifier circuit (9) outputs a transistor activation signal that turns on the transistor (13) when the output voltage of the detector (8) exceeds the current limiting reference voltage.

When the accelerator is operated, a voltage proportional to the amount of accelerator operation is input to the PWM modulation circuit (14), and a PWM signal with a pulse width proportional to this voltage is output from the PWM modulation circuit (14). The power transistor (5f) or (5r) selected by the forward changeover switch (21) is controlled on and off according to the PWM signal,
This drives the DC motor.

On the other hand, a voltage proportional to the motor current outputted from the armature current detector (8) and a current limiting reference voltage are compared by a differential amplifier circuit (9).

When the output voltage of the detector (8) exceeds the current limiting reference voltage, the transistor (13) is turned on,
Voltage input to the PWM modulation circuit (14) is cut off. The operation under such high loads is similar to that of the current control method.

FIG. 8 shows the load voltage waveform and average load voltage. The average load voltage Vm is the power supply voltage of the storage battery (3)
bb, it is expressed by the following formula.

Vm-V b b -Ton/ (Ton+Toff'
) FIG. 9 shows the characteristics of the DC motor obtained by the voltage control method described above, and shows the relationship between the rotational speed N and the generated torque T.

Curve A shows the static characteristic curve of a DC motor. Torque T1 indicates the additional torque during steady running, and speed N1 indicates the speed corresponding to T1.

Curve AL is an operation with a relatively small amount of accelerator operation! The curve AH shows the characteristics of the DC motor when the accelerator operation amount is SL, the curve AH shows the characteristics of the DC motor when the accelerator operation amount is a relatively large operation amount AH, and the curve AM shows the characteristics of the DC motor when the accelerator operation amount is an intermediate value SM between SH and SL. Each shows the characteristics of a DC motor at a certain time. At high loads, current limiting operation
Torque is limited to a constant value. Speeds NL, NM and N
H means the accelerator operation amount is SL.

Steady running speeds in SM and SH are shown.

In the voltage control method described above, in a load range where the motor current is equal to or less than a predetermined current limit, a pulse width proportional to the accelerator operation amount, that is, an average motor voltage is supplied to the motor. When the accelerator operation amount is SL, the speed NL, when the accelerator operation amount is SM, the speed NM, and the accelerator operation amount is S.
At H, a speed proportional to the accelerator operation amount, such as speed NH, is obtained.

During plugging, even if the accelerator operation amount is a relatively small value SL, the motor current increases to the limit current value, so a braking force proportional to the accelerator operation amount cannot be obtained. When the amount of accelerator operation is large, the plugging characteristics are the same as those of the current control type, but even when the amount of accelerator operation is small, a large braking force is generated, so a shock is generated during plugging.

Means for Solving the Problems A control device for a DC series motor for an electric vehicle according to the present invention has the following features:
A current detector detects the motor current, a plugging detector detects the plugging state, and the detected current of the current detector is compared with the limit current, and while the detected current exceeds the limit current, the output signal of the chopper control circuit is a limiting current control means that sets the limiting current to a predetermined reference value for overcurrent protection during normal running, and sets the limiting current to a value according to the accelerator operation amount when a plugging state is detected; and a chopper control circuit during normal running. A speed command signal control means is provided which sets the speed command signal inputted to the accelerator to a value corresponding to the accelerator operation amount, and sets the speed command signal to a value corresponding to the accelerator operation amount or a predetermined constant value when a plugging state is detected. shall be.

Effect of the Invention During normal running, the limiting current is set to a predetermined reference value for overcurrent protection, and the speed command signal input to the chopper control circuit is set to a value corresponding to the accelerator operation amount, resulting in voltage control type control. .

When the plugging state is detected, the limiting current is set to a value corresponding to the accelerator operation amount, and the speed command signal input to the chopper control circuit is set to a value corresponding to the accelerator operation amount or a predetermined constant value, resulting in current control type control. .

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows an embodiment of the invention.

In FIG. 1, the same parts as in FIG. 7 are given the same reference numerals, and their explanations will be omitted.

The input terminal of the PWM modulation circuit (14) is connected to the output terminal of a voltage divider (10) whose voltage division ratio is controlled in accordance with accelerator operation, and the 1b contact (31bL) for driving mode and the resistor R4.
is connected to the reference voltage generation power supply (
30) is the 1st a contact (31al) for plugging mode
and are connected via resistor R4.

The reference voltage generation power source (30) is connected to the inverting input terminal of the differential amplifier circuit (9) through the second b contact (31b2) for driving mode.
and a resistor R3, and the output terminal of the voltage divider (10) is connected to a plugging mode second a contact (31a2) and a resistor R3.

A plugging detector (31) is connected in parallel to the armature circuit. The plugging detector (31) detects the plugging state based on the inversion of the voltage applied to the armature (1) during plugging, and detects the plugging state based on the reversal of the voltage applied to the armature (1) during plugging, and
2).

During normal running, the 1st b contact for running (31bl) and the 2nd b contact for running (31b2) are in the on state. Therefore, the PWM modulation circuit (14) includes a voltage divider (
10) (accelerator voltage) is input via resistor R4. In addition, the inverting input terminal of the differential amplifier circuit (9) is
The power supply voltage of the reference voltage generation power supply (30) is inputted via the resistor R3. As a result, during normal running, the operation of this motor control circuit is similar to that of the voltage control type motor control circuit shown in FIG. Therefore, a speed proportional to the amount of accelerator operation can be obtained.

In other words, when the accelerator is operated, the PWM modulation circuit (1
4) A voltage proportional to the amount of accelerator operation is input, and PWM
A pulse width P proportional to this voltage is output from the modulation circuit (14).
A WM signal is output. And forward/forward changeover switch (
21) selected by the power transistor (5
f) or (5r) is controlled to be turned on or off according to the PWM signal, thereby driving the DC motor.

When the output voltage of the motor current detector (8) exceeds the power supply voltage of the reference voltage generation power supply (30), the transistor (
13) is turned on, and the voltage input to the PWM modulation circuit (14) is cut off.

During plugging, the plugging detector (31) detects the 1st b contact (81bl) for running and the 2nd contact for running.
The b contact (31b2) is turned off and the first
A contact (31al) and the 28th contact for plugging (
31a2) is turned on.

Therefore, the power supply voltage of the reference voltage generation power supply (30) is input to the PWM modulation circuit (14) via the resistor R4. Further, the output (accelerator voltage) of the voltage divider (10) is inputted to the inverting input terminal of the differential amplifier circuit (9) via a resistor R3. That is, the voltage (limited current value) input to the inverting input terminal of the differential amplifier circuit (9) has a value proportional to the accelerator voltage. As a result, during plugging, the operation of this motor control circuit is similar to that of the current control type motor control circuit shown in FIG. Therefore, at the time of plugging, a braking force corresponding to the accelerator operation amount can be obtained, so that smooth plugging can be performed.

Figure 2 shows the main parts of the control circuit in Figure 1 (symbols in Figure 1).
40) is shown. The output of the voltage divider (10), whose voltage division ratio is controlled in accordance with the accelerator operation, is sent to the PWM modulation circuit (14) via the diode (41), as well as the diode (60) and the resistor (6).
1), it is also sent to the light emitting diode of the photocoupler (57). This photocoupler (57) is used in an analog operation region, and the equivalent resistance between the collector and emitter of the phototransistor in the photocoupler (57) changes depending on the output voltage of the voltage divider (10).

The output voltage of the armature current detector (8) is input to the non-inverting input terminal of the running current limiting voltage comparator (43). The output of the limiting current setting voltage divider (42) is input to the inverting input terminal of the voltage comparator (43). The output of the running current limiting voltage comparator (43) is connected to the diode (44).
) and the photocoupler (46) via the resistor (45).
light emitting diode. The collector of the phototransistor of the photocoupler (46) is connected to a DC power supply via a resistor (47). The emitter of this phototransistor is a resistor (48) and a diode (49)
It is connected to the base of the switching transistor (13) via.

The detection signal voltage of the armature current detector (8) is further input to the non-inverting input terminal of the plugging current control voltage comparator (50). The inverting input terminal of the voltage comparator (50) is connected to the DC power supply VP1 via a resistor (58). The output of the voltage comparator (50) is passed through a diode (44) and a resistor (45) to a photocoupler (
46) is sent to the light emitting diode.

The inverting input terminal of the voltage comparator (50) is further connected to a resistor (
59) and the output terminal of the voltage comparator (5B) via the phototransistor of the photocoupler (57). This voltage comparator (56) outputs a voltage at the same level as the power supply voltage of the DC power supply VP1 when the input voltage at its non-inverting input terminal is greater than the input voltage at its inverting input terminal. Therefore, the inverting input side of the voltage comparator (50) becomes a high level voltage, no voltage is generated from the output side of the voltage comparator (50), and its operation is blocked. When the input voltage at the non-inverting input terminal of the voltage comparator (56) is smaller than the input voltage at its inverting input terminal,
The output terminal is in a retracting operation, and the emitter side of the phototransistor of the photocoupler (57) is grounded.

The output of the voltage divider (55) for adjusting the plugging detection level is input to the non-inverting input terminal of the voltage comparator (5B). A resistor (53) connected between the DC type 1iXVP2 and the ground is connected to the inverting input terminal of the voltage comparator (56).
The voltage across the terminals of a resistor (54) in a series circuit consisting of a phototransistor of a photocoupler (52) and a resistor (54) is input. The output of the plugging detector (31) is sent to the light emitting diode of the photocoupler (52).

During normal driving, the plugging detector (31) does not output a plugging detection signal, and the photocoupler (5)
The light emitting diode in 2) is off, and the phototransistor is also off. Therefore, the input voltage at the inverting input terminal of the voltage comparator (5G) is smaller than the input voltage at the inverting input terminal. Therefore, during normal running, no current flows through the resistor (59).

For this reason, a voltage comparator (50
) is equal to the power supply voltage of the DC power supply VPI. Since the Wi power supply voltage of the DC power supply vP1 is set higher than the output voltage of the limit current setting voltage divider (42), during normal running, the switching transistor (13) )
is controlled by the output of Therefore, the motor is controlled using a voltage control method.

During plugging, a plugging detection signal is output from the plugging detector (31), so the light emitting diode of the photocoupler (52) is turned on, and the phototransistor is also turned on. Therefore, the voltage comparator (56)
The input voltage at the inverting input terminal of is greater than the input voltage at the non-inverting input terminal. Therefore, current flows from the power supply VPI to the resistor (58), resistor (59) and photocoupler (57).
), the power supply voltage flows through the phototransistor of the resistor (58
) and a resistor (59) and sent to the inverting input terminal of a voltage comparator (50) for current control during plugging.

Since the photocoupler (57) has a light emitting diode flowing through it, a current corresponding to the amount of accelerator operation flows, so the photocoupler (57)
The current flowing through the phototransistor 57) also has a value corresponding to the accelerator operation amount.

For this reason, a voltage comparator (50
) also has a value corresponding to the accelerator operation amount. The input voltage of the inverting input terminal of the voltage comparator (50) during plugging is determined by the limit current setting voltage divider (42).
Since it is set to be smaller than the output voltage of
When plugging, the switching transistor (13
) is controlled by the output of the current control voltage comparator (5G) during plugging. Therefore, the motor is controlled using a current control method.

Effects of the Invention In the control device for a DC series motor for an electric vehicle according to the present invention, control is performed using a voltage control method, and a speed proportional to the accelerator operation amount can be obtained. During plugging, current control is used to obtain a braking force proportional to the amount of accelerator operation, allowing for smooth plugging without impact.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing an embodiment of the present invention, Fig. 2 is an electric circuit diagram showing a modification of the main parts of Fig. 1, and Fig. 3 is an electric circuit diagram showing a current control type motor control circuit. , FIG. 4 is a time chart showing both input voltage waveforms of the differential amplifier circuit of FIG. 3, FIG. 5 is a time chart showing the output voltage waveform of the differential amplifier circuit of FIG. 3, and FIG. Fig. 7 is a graph showing the relationship between rotational speed and generated torque, showing the characteristics of a DC motor obtained by the motor control circuit shown in Fig. 7. Fig. 7 is an electric circuit diagram showing a voltage control type motor control circuit. The figure is a time chart showing the load voltage waveform and average load voltage obtained by the motor control circuit of FIG.
FIG. 9 shows the characteristics of the DC motor obtained by the motor control circuit shown in FIG. 7, and is a graph showing the relationship between rotational speed and generated torque. (1) Armature of DC series motor, (3) Storage battery, (4r) (4r) Field winding, (5f) (5
rl...power transistor (chopper transistor), (8)...armature current detector (motor current detector), (9)...differential amplifier circuit, (10)...voltage divider, ( 13)...Switching transistor, (■4
)...PWM modulation circuit (chopper control circuit), (3
0)...DC power supply, (31)...Plugging detector, (42)...Limit current setting voltage divider, (43)...
・Voltage comparator for current limitation during running, (4B) (52)
(57)...Photo coupler, (50)...Voltage comparator for current control during plugging. that's all

Claims (1)

[Claims] A current detector that detects a motor current, a plugging detector that detects a plugging state, a chopper that compares the detection current of the current detector with a limit current, and while the detected current exceeds the limit current. a means for cutting off the output signal of the control circuit; a limiting current control means that sets the limiting current to a predetermined reference value for overcurrent protection during normal driving; and sets the limiting current to a value corresponding to the accelerator operation amount when a plugging state is detected; Speed command signal control means that sets the speed command signal input to the chopper control circuit at a value corresponding to the accelerator operation amount during traveling, and sets the speed command signal to a value corresponding to the accelerator operation amount or a predetermined constant value when a plugging state is detected; A control device for a DC series motor for electric vehicles.