JPH02159904A - Regenerative start control circuit for electric vehicle - Google Patents

Abstract

PURPOSE:To protect a contact from burning, to ensure regenerative brake force upon droppage of battery voltage and to protect a power transistor from breakdown by controlling the starting time of regenerative brake according to rotation, current of a DC motor, battery voltage and accelerating condition. CONSTITUTION:When transition is made from traveling condition to regenerative brake condition, an AND gate 11 produces a high level output if the voltage (VB) of a battery 61 is higher than a predetermined value (VC) and the rotation (RM) of a motor 63 is lower than a predetermined value (RC1) or if the voltage VB once drops below the voltage VC and the rotation RM is lower than a predetermined value (RC2)(RC2<RC1). Consequently, an AND element 13 produces a high level output and a FET 14 is turned ON. As a result, voltage drop occurs across a resistor 15 and the collector-emitter voltage of a transistor 68 has low level thus starting regenerative brake.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a regenerative start control circuit for an electric vehicle.

[Conventional technology]

FIG. 3 shows a conventional example. The conventional example shown in FIG. 3 includes a DC motor drive circuit 60 that drives a DC motor 63 with a battery 61, and a regenerative braking circuit that performs regenerative braking using electrical energy generated by the DC motor 63. A contactor synchronized with the accelerator is provided for switching between the DC motor drive circuit 60 and the regenerative braking circuit.

Specifically, the DC motor drive circuit 60 includes a battery 61
, a contactor 62, a DC motor 63, and a diode 64 are connected in series.

The regenerative braking circuit includes a power generation circuit 80 that stores electrical energy generated by the DC motor 63 in the field coil 65, and a charging circuit 70 that charges the battery 61 with the electrical energy stored in the field coil 65. has been done.

A switching signal output circuit 90 outputs a predetermined control signal in response to a motor current signal of the DC motor 63, and an output signal of the switching signal output circuit 90 causes the power generation circuit 80 or the charging circuit 70 to be set in either mode. A power transistor 68 is provided as a switching control means for switching and selecting.

Of these, the power generation circuit 80 specifically includes a power transistor 68, a motor current detection circuit 66, a field coil 65, a contactor 64, a DC motor 63, and a diode 64 connected in series. ing.

The charging circuit 70 also includes a field coil 65, a contactor 64, a DC motor 63, a diode 64, a battery 61, a diode 67, and a motor current detection circuit 66.
are connected in series.

Additionally, there is an accelerator state detection circuit 25 that outputs an accelerator state signal that indicates whether the contactor 64 is on the traveling side (A) or the regeneration side (B), and an accelerator state detection circuit 25 that outputs an accelerator state signal that indicates whether the contactor 64 is on the traveling side (A) or the regeneration side (B), and the relay contact is set to either the traveling side or the regeneration side depending on the accelerator state signal. Relay circuit 10 connected to
0 is provided.

A relay drive signal output circuit 110 is provided which receives an accelerator state signal and a motor current signal output from the motor current detection circuit 66 and outputs a relay drive signal to the relay circuit 100.

Next, the operation of the above conventional example will be explained.

When the accelerator is released, the microswitch inside the accelerator is switched, and the contactors 62 and 64 are also switched to the regeneration side. Then, the accelerator state signal becomes "high" level, the output signal of the relay drive signal output circuit 110 becomes "high" level, and the relay contact of the relay circuit 100 goes to the regeneration side (B).
become. This activates regenerative braking.

When regenerative braking is activated, the motor current gradually increases.

When the motor current signal exceeds a certain value, the output signal of the relay drive signal output circuit 110 becomes a "low" level, and the relay contact of the relay circuit 100 becomes the negative side (A). This ends the activation of regenerative braking.

[Problem to be solved by the invention]

However, in the above conventional example, the regenerative braking start timing is controlled only in the accelerator state, and the contactor contact switches from the power side to the regenerative side and at the same time switches from the DC motor drive circuit to the regenerative braking circuit. If contactor contact burnout occurs due to contactor contact bounce, or if the battery discharge progresses and the voltage drops, the power transistor will be switched on and off frequently, which increases switching loss. In some cases, the power transistor may be damaged.

[Purpose of the invention]

The purpose of the present invention is to improve the disadvantages of the conventional example, to prevent burnout of the contactor contacts, to ensure sufficient regenerative braking force even when the battery voltage drops such as at the end of discharge, and to provide a power transistor. An object of the present invention is to provide a regenerative start control circuit for an electric vehicle that can effectively reduce damage to the electric vehicle.

[Means to solve the problem]

The present invention includes a DC motor drive circuit that drives the DC motor using a battery, and a regenerative braking circuit that performs regenerative braking using electrical energy generated by the DC motor.

Then, a contactor for switching between the DC motor drive circuit and the regenerative braking circuit in synchronization with the accelerator, an accelerator state detection circuit for knowing the state of this contactor, and a motor current detection circuit for measuring the motor current are installed. We are prepared. Further, the DC motor is provided with a regenerative braking start timing control circuit that controls the regenerative braking start timing based on the motor rotational speed, motor current, battery voltage, and accelerator state of the DC motor. This aims to achieve the above-mentioned purpose.

[For production]

When the vehicle shifts from driving to braking, the regenerative braking start timing control circuit detects the accelerator state and battery voltage at that time.
If the battery voltage is above a certain value (e.g. 80V),
When the motor rotation speed reaches a certain value (for example, 5000 rpm), regenerative braking is activated. Also, the battery voltage is at a certain value (
For example, if the motor rotation speed is less than 80 cm), regenerative braking is further delayed until the motor rotation speed reaches a certain value (for example, 350.Qrpm).

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The embodiment shown in FIG. 1 includes a DC motor drive circuit 60 that drives a DC motor 63 by a battery 61;
It has a regenerative braking circuit that causes the DC motor 63 to generate electricity and perform regenerative braking. Then, the DC motor drive circuit 6
A contactor synchronized with the accelerator is provided for switching between zero and regenerative braking circuits.

Specifically, the DC motor drive circuit 60 includes a battery 61
, a contactor 62, a DC motor 63, and a diode 64 are connected in series.

The regenerative braking circuit includes a power generation circuit 80 that stores electrical energy generated by the DC motor 63 in the field coil 65, and a charging circuit 70 that charges the battery 61 with the electrical energy stored in the field coil 65. ing.

A switching signal output circuit 90 outputs a predetermined control signal in response to a motor current signal of the DC motor 63, and an output signal of the switching signal output circuit 90 causes the power generation circuit 80 or the charging circuit 70 to be set in either mode. A power transistor 68 is provided as a switching control means for switching and selecting.

Of these, the power generation circuit 80 specifically includes a power transistor 6, a motor current detection circuit 66, a field coil 65, a contactor 64, a DC motor 63, and a diode 64 connected in series. has been done.

The charging circuit 70 also includes a field coil 65, a contactor 64, a DC motor 63, a diode 64, a battery 61, a diode 67, and a motor current detection circuit 66.
are connected in series.

Furthermore, a motor rotation speed detection means 50 that detects the motor rotation speed of the DC motor 63, and an accelerator state detection circuit 25 that outputs an accelerator state signal that indicates whether the contactor 64 is on the drive side or the regeneration side are provided.

The motor rotation speed detecting means 50 includes a flywheel 51 having a ring gear attached to the armature shaft of a DC motor 63, a pulse pickup 52 installed near the flywheel 51, and an output of the pulse pickup 52. It is composed of frequency-voltage conversion amplifiers 53 arranged in stages.

Further, the DC motor 63 is provided with a regenerative braking start timing control circuit 10 that outputs a regenerative braking start command signal.

The regenerative braking start timing control circuit 10 includes a battery voltage drop detection circuit 20 that outputs a "low" level when the voltage of the battery 61 falls below a certain value (for example, 80V), and a motor rotation speed detection circuit 20 that outputs a "low" level when the voltage of the battery 61 falls below a certain value (for example, 80V). When the rotation speed exceeds a certain value (for example, 5000 rpm), it becomes "low".
A motor overspeed detection circuit 40 that outputs a level, a battery voltage n, and a motor rotational speed signal 0 are input, and the battery voltage n becomes less than a certain value (for example, 80V) even once.

and the motor rotation speed is a certain value (for example, 3500 rpm)
The regenerative braking start timing correction circuit 30 outputs a "low" level until 4-game AND which inputs the timing signal C, the accelerator state signal d, and the battery voltage discrimination signal f which is the output of the battery voltage drop detection circuit 20.
element 11 and a motor current signal e which is the output of the motor current detection circuit 66 as a clock input, and a 4-game) AND element 1
A D-type flip-flop element 12 which uses the output signal g of 1 as a data input and a reset input, and a 4-game) AND
2-game) AND element 1 whose inputs are the output signal g of the element 11 and the output signal of the D-type flip-flop element 12.
3 and a power MO3FET 14 whose gate input is the output signal of the 2-game AND element 13. The source of the power MO3FET 14 is connected to the DC motor 6, 3, and the drain is grounded.

Motor current signal e which is the output of motor current detection circuit 66
is also an input of the switching signal output means 90, and the switching control signal which is the output of the switching signal output means 90 is the gate input of the power transistor 68.

Next, the operation of this embodiment will be explained.

The flywheel 51 attached to the armature shaft of the DC motor 63 rotates in conjunction with the DC motor 63. Furthermore, since the flywheel 51 is provided with a ring gear, by measuring the period of the unevenness of the ring gear with the pulse pickup 52, a frequency pulse proportional to the rotation speed of the DC motor 63 can be obtained.

Further, this frequency pulse is converted and amplified by a frequency-voltage conversion amplifier 53 into a DC voltage signal proportional to the frequency.

Then, the motor rotation speed is set to a certain value (for example, 5000r
pm), the motor rotation speed determination signal e, which is the output of the motor overspeed detection circuit 40, becomes a "low" level.

When the voltage of the battery 61 becomes less than a certain value (for example, 80 cm), the battery voltage discrimination signal f, which is the output of the battery voltage drop detection circuit 20, becomes a "low level".

The regenerative braking starting timing signal C, which is the output of the regenerative braking starting timing correction circuit 30, indicates that if the battery voltage even once falls below a certain value (for example, 80V), the motor rotation speed will reach a certain certain value (
For example, it outputs a "low" level until the speed reaches 3,500 rpm.

In the accelerator state detection circuit 25, the contactor 64 outputs an accelerator state signal d which is at a "low" level on the row side and a "hyper level" on the regeneration side.

4 game) AND element 11 outputs the motor rotation speed determination signal e.
When the regenerative braking start timing signal C, accelerator state signal d, and battery voltage determination signal f are all at the "high" level.
High level output.

The motor current signal that is the output of the motor current detection circuit 66 is a pulse signal that becomes a "high" level when the motor current reaches a certain value, and remains at the "high" level for a certain period of time.

Therefore, the D-type flip-flop element 12 which receives the motor current signal as a clock input outputs a low level at the first rising pulse of the motor current signal.

2 gate AND element 13, 4 gate) AND element 11
When the output signal g of the D-type flip-flop element 12 and the output signal of the D-type flip-flop element 12 are both "high", the output signal is "high".
It becomes a level output.

In the power MO3FET 14, when the gate input becomes "high" level, the motor current flows between the source and drain of the power MO3FET 14 to turn on, and the resistor 1
5, a voltage drop occurs, and the collector-emitter voltage of the power transistor 68 becomes a "low" level and regenerative braking is activated.

- Once regenerative braking is started, regenerative braking is performed that is defined by motor current, motor rotation speed, battery voltage, etc.

〔Effect of the invention〕

Since the present invention is configured and functions as described above, according to this, when moving from a running state to a regenerative braking state, the rotation speed of the motor becomes a predetermined value due to the action of the regenerative braking start timing control circuit. The start time of regenerative braking can be delayed until Therefore, it is possible to prevent burnout due to bounce of the contactor contacts for switching between the DC motor drive circuit and the regenerative braking circuit. Furthermore, sufficient regenerative braking force can be ensured even when the battery voltage drops, such as at the end of discharge, and the frequency of on/off switching of the power transistor can be reduced, thereby reducing switching loss. In addition, it is possible to provide an unprecedented and excellent regenerative start control circuit for an electric vehicle that can effectively reduce damage to power transistors and the like.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2(a)
～(m) are the DC motor rotation speed signal, battery voltage, regenerative braking start timing signal, accelerator state signal, motor rotation speed determination signal, battery voltage determination signal, regenerative braking start command signal, and collector emitter of the power transistor in Figure 1. Figure 3 is a diagram showing the time variation of the voltage between the motors, the motor current, the motor current signal, the output signal of the flip-flop element, the output signal of the 2-gauge AND element, and the source-drain current of the power MOS FET. Figure 3 shows the configuration of a conventional example. It is a diagram. lO...Regenerative braking start timing control circuit, 25...
・Accelerator state detection circuit, 50...Motor rotation speed detection means, 60...DC motor drive circuit, 6
1...Battery, 62.64...Contactor, 63...DC motor, 65...
・Field coil, 66...Motor current detection circuit,
70... Charging circuit, 80... Power generation circuit, d... Accelerator state signal, j... Motor current signal, n... Battery Voltage, 0...
...Motor rotation speed signal.

Claims (1)

[Claims] (1) It has a DC motor drive circuit that drives the DC motor with a battery, and a regenerative braking circuit that performs regenerative braking using the electrical energy generated by the DC motor, and the DC motor drive circuit and the regenerative braking circuit can be switched. A contactor for synchronizing with the accelerator, an accelerator state detection circuit attached to this contactor that outputs an accelerator state signal to know when to switch the contactor, and an accelerator state detection circuit connected in series to the field coil of the DC motor to detect the motor current. In the regenerative start control circuit for an electric vehicle, the circuit includes a motor current detection circuit that outputs a signal, and a motor rotation speed detection means that is attached to a DC motor and detects the rotation speed of the DC motor and outputs a motor rotation speed signal. Regeneration of an electric vehicle, characterized in that the DC motor is provided with a regenerative braking start timing control circuit that controls the regenerative braking start timing based on a motor rotation speed signal, a motor current signal, a battery voltage, and an accelerator state signal of the DC motor. Start-up control circuit.