JPS6223549B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor control device using a microcomputer, and particularly to a motor control device suitable for use in an electric vehicle.

Electric motors are generally controlled using command values obtained by operating command devices such as accelerator pedals and brake pedals.
It compares the detected value of the actual motor current and generates gate pulses for turning on and off the chopper circuit so that the motor current matches the command value within the limit value range. At this time, it is necessary to deal with changes in operating modes such as power running and regeneration, and to accurately control the timing of gate pulse generation to avoid commutation failure. For this reason, a method is known, for example, as disclosed in JP-A-53-74221, in which an interrupt is generated immediately after the off-pulse is generated in the chopper circuit, and a motor current close to the peak value is taken in to calculate the conduction rate.

However, due to the configuration of the main circuit, detecting the current value of the DC power supply (battery) with a current detector and replacing it with the motor current value may make the overall configuration cheaper than directly detecting the motor current. In such a configuration, since battery current does not flow after the off-pulse is generated, it cannot be replaced as a motor current. Further, a technique for controlling the tipper current by using the average value of the current twice in one cycle immediately after the tipper is turned on and immediately after the tipper is turned off as a feedback amount is also known, for example, in Japanese Patent Laid-Open No. 103524/1983. In this case, there is a problem that immediately after the chopper is turned off, no current flows to the DC power supply side and cannot be used as a motor current.

An object of the present invention is to enable the motor current to be taken in at a time close to its peak value, regardless of the connection position of the current detector in the main circuit.

A feature of the present invention is that the microcomputer is interrupted immediately before the chopper circuit is turned off (approximately a certain period of time), and the interrupt program causes the motor current to be detected.

Embodiments of the present invention will be explained with reference to FIG. 1 and subsequent figures.
FIG. 1 is a basic configuration diagram of an electric vehicle control device according to an embodiment of the present invention. Reference numeral 1 designates a microcomputer, which includes a microprocessor 2, a random access memory 3, a read-only memory 4, an oscillator 5, and a bus line 6 for address, data, and control. 7 is an analog input circuit, which outputs analog electric signals ACA,
This is a circuit that converts a plurality of analog signals obtained from the detection signals of the operating states of the BRA and the main circuit 10 via the level conversion circuit 11 into digital signals and captures the digital signals, and one embodiment thereof is shown in FIG. The level conversion circuit 11 is composed of six circuits, including an amplifier 10 that amplifies the output IM of the armature current detector.
1. Amplifier 10 that amplifies the output of the field current detector
2. An amplifier 103 that amplifies the output of the battery temperature detector, an amplifier 104 that amplifies the output TM of the motor temperature detector, and an amplifier that amplifies the output TT of the detector that detects the temperature of the main thyristor constituting the main circuit 10. 105, it is composed of a voltage dividing circuit 106 that lowers the battery voltage VB to a low voltage. Further, the analog input circuit 7 is an analog multiplexer 10.
7, an A/D converter 108, a register 109, and an analog input control circuit 110. Now, when a signal is given from the microprocessor 2 to the AIC shown in FIG.
The analog input specified by A/D converter 108
The multiplexer 107 is operated to connect to. Also, at the same time, start up the A/D converter 108,
The designated analog quantity is converted into a digital quantity and held in the register 109. As a result, the microprocessor 2 can take in the specified analog amount by reading the AI value.

12 is a digital input circuit, which receives a 1-bit accelerator switch signal ACD from the accelerator device 8 that indicates that the accelerator pedal has been depressed, and a 1-bit brake switch signal from the brake device 9 that indicates that the brake pedal has been depressed.
The signal KSD from the BRD and key switch 13 is taken in, and the signal is converted by the circuit shown in FIG. 3 to be input to the microcomputer.
That is, the digital input circuit 12 is a resistor connected to the power supply V _CC of the microcomputer 1.
It consists of R ₁ , R ₃ , R ₅ , resistors R ₂ , R ₄ , R ₆ and capacitors C ₁ , C ₂ , C ₃ that constitute a first-order lag filter. Now, when the accelerator switch SWA is open, a voltage of V _CC is generated at DIA. Furthermore, when the accelerator switch SWA is closed, 0V is output to DIA. Note that the filter with R ₂ and C ₁ is for noise prevention. Similarly, the brake switch
When SWB and key switch SWK operate, voltage V _CC or 0V is output to DIB and DIK depending on the operation.

The interrupt circuit 14 has a configuration as shown in FIG. In the example shown in FIG. 4, the circuit receives interrupt pulses INP1 to INP4 from four sources. Now, when a pulse is generated on INP1, the flip-flop circuit 111 is set and the output becomes the IND1 level. On the other hand, interrupt pulse INP1 is OR circuit 1
15, and provides an interrupt pulse INT to the microprocessor 2. As a result, microprocessor 2 takes in the contents of IND and also outputs reset pulses for flip-flops 111 to 114.
Generate INRE. Then, looking at the contents of IND,
If IND1 is at level 1, it is assumed that an interrupt has occurred in that part, and the interrupt processing is executed.
The same applies when an interrupt pulse is input to INP2 to INP4.

Returning to FIG. 1, 15 is a conduction rate control circuit for the armature chopper and field chopper, and 2
The two square waves are divided by the pulse distribution circuit 16 into on-pulses and off-pulses of the armature chopper. These pulse signals are amplified by the amplifier circuit 17 and become control signals for the chopper in the main circuit 10. FIG. 5 shows the details of this portion of the circuit, and FIG. 6 shows some of its operating waveforms. The conduction rate control circuit 15 includes a counter 116 and a register 1.
17, 118, digital comparator 119, 12
0, a matching circuit 121. Counter 116 counts the clock pulses CLO produced by oscillator 5. However, the counter 116 is a down counter. As a result, the output of the counter 116
COUT exhibits sawtooth wave characteristics as shown in FIG.
The output COUT of this counter 116 is, as shown in FIG.
17,118 value and digital comparator 119,1
It is compared with 20. And digital comparator 1
When the values in the registers 117 and 118 become larger than the counter value COUT, the square wave signals 19 and 120 become 1 level. Also, counter 1
The output COUT of 16 becomes the input of the matching circuit 121, and the value of COUT becomes COUTL as shown in FIG.
When this happens, a pulse INP1 of a constant width is generated. This INP1 pulse becomes the interrupt pulse shown in FIG. 4 described above, and interrupts the microprocessor 2.
Further, as shown in the operating waveform of FIG. 6, the pulse of INP1 is generated a certain period of time before the pulse of APF is generated.

Specifically, the time from the on-pulse to the off-pulse when the conductivity of the chopper is at its minimum (usually 300μ
A specific time ΔT slightly shorter than sec~500μsec)
(arbitrary setting) occurs before.

Furthermore, each of the interrupt cause pulses INP1 to INP4 becomes an input to the OR gate circuit 115 and is directly applied to the interrupt terminal of the microprocessor 2 as INT.

In the example shown in FIG. 6, only INP1 is used for interrupts. Therefore, INP2 to INP4 in FIG. 4 are not used in this example, but can be used depending on the purpose. For example, since the field current response is slower than the armature current, INP1 detects only the armature current,
Alternatively, commutation failure may also be detected, and the field current may be detected only once every plurality of chopper cycles or asynchronously at INP2, which is interrupted. Further, the INP 3 may be made to perform an interruption to give priority to processing for emergencies.

The pulse distribution circuit 16 shown in FIG. 1 is constructed as shown in FIG. A monostable circuit 122 that generates a constant width pulse in synchronization with the rising edge of the output square wave of the digital comparator 119, a monostable circuit 123 that generates a constant width pulse in synchronization with the falling edge, and two AND gate circuits. It consists of 124 and 125. SUP, which is one input of the AND gate circuits 124 and 125, sets this signal to 0 level when the microcomputer 2 wants to stop generating pulses. Now, when SUP is at 1 level, the outputs of the monostable circuits 122 and 123 directly become the outputs of the AND gate circuits 124 and 125, resulting in signals such as APO and APF in FIG. The outputs of the AND gate circuits 124 and 125 are amplified by pulse amplifiers 126 and 127, and become an ON gate pulse APGO and an OFF gate pulse APGF, respectively, of a thyristor chopper for armature current control, which will be described later. Also, the digital comparator 12
The output square wave of 0 is amplified by amplifier 128;
This becomes a base drive signal for a field current control transistor chopper, which will be described later.

The main circuit 10 has the configuration shown in FIG. A battery 130 is used as a power source, and a thyristor chopper circuit 131 controls the armature current of the shunt motor 132, and a transistor chopper circuit 133 controls the current flowing through the field winding 134 of the shunt motor 132. The thyristor chopper circuit 131 includes a main thyristor 135, an auxiliary thyristor 136, a diode 137, a commutating capacitor 138, and a commutating reactor 139. The commutating capacitor 138 includes an auxiliary charging diode 140 and a resistor 1.
41 is connected. Furthermore, 142 is a flywheel diode for the shunt motor 132 and the DC reactor 144. Furthermore, 143 is a flywheel diode for the rotating magnetic winding. 145 is a power supply/disconnection switch, which is turned on with a manual lever installed in the driver's seat, and the signal is turned on.
Pull it open with a FET. 146A and 146B are the contacts of the contactor 146, and when the contactor control signal CON is at 0 level, the state shown in FIG. C.B.
Connected to CBM. This contactor 146 performs switching between power running and regeneration. That is,
The state shown in FIG. 7 shows the regeneration mode, and when the thyristor chopper circuit 131 is turned on, the induced voltage of the shunt motor 132 is short-circuited via the DC reactor 144, and when it is turned off after a certain period of time, the shunt motor 132 is short-circuited. The induced voltage of DC reactor 144 is regenerated to battery 130 via flywheel diode 142. During this time, the field current is controlled by the chopper circuit 133. In this way, regeneration operation is performed. On the other hand, the contactor excitation signal
When CON becomes 1 level and the contactor 146 operates, terminals CA and CAM are connected, and terminals CB and CBM are connected. In this state, thyristor chopper circuit 1
31, the voltage of the battery 130 is applied to the shunt motor 132, and the current flowing through the shunt motor 132 increases. Further, when the thyristor chopper circuit 132 is turned off, the current flowing through the shunt motor 132 is attenuated through the DC reactor 144 and the flywheel diode 142, thereby performing a powering operation.

Note that 147 and 148 are fuses for protection. Further, 149 and 150 are a shunt resistor for armature current detection and a shunt resistor for field current detection, respectively, and are connected to the amplifiers 101 and 10 in FIG.
The value is taken into the microcomputer 1 via the microcomputer 2. 151, 152, and 153 are thermistors that detect the temperatures of the battery 130, the main thyristor 135, and the shunt motor 132, respectively, and the amplifiers 103, 104, and 1 of FIG.
The value is taken into the microcomputer 1 via the microcomputer 05.

Returning to FIG. 1, 18 is a power digital output circuit, which outputs the signal SUP for suppressing the gate pulse shown in FIG. 5, and the contactor 1 shown in FIG.
46, generate excitation signals CON and FET for the switch 145.

19 is a speed detection circuit, and a pulse generator 2 generates pulses corresponding to the rotational position and whose frequency is proportional to the speed of the shunt motor 132.
The speed is digitally detected based on the zero output pulse train PLP and is input into the microcomputer 1.

An embodiment of the speed detection circuit is shown in FIG. a counter 155 for generating pulses at time intervals serving as a reference for measuring speed;
A monostable circuit 156 that generates a pulse of a constant width in synchronization with the falling edge of the overflow pulse of , a counter 157 for counting the output pulse PLP of the pulse generator 20, and a register that holds the output of the counter 157 at regular intervals. It consists of 158 pieces. Since the counter 157 is reset at fixed time intervals by the output pulses of the monostable circuit 156, the speed can be detected from the number of pulses that have arrived at a fixed time, that is, the output of the counter. Note that the output of the counter is set in the register 158 by the overflow pulse of the counter 155 immediately before the reset pulse is input. The microcomputer 1 can detect the speed by reading the contents of this register 158. Note that the clock pulse of the counter 155 is the reference pulse of the oscillator 5 in FIG.
I am using CLO.

Returning to FIG. 1 again, 21 is a digital output circuit, which is provided to light up a lamp on a panel 22 provided at the driver's seat.

All operations of the control device shown in FIG. 1 are performed by sequentially processing the contents of the program written in the read-only memory 4. The details of this process will be explained below.

There are roughly two types of programs written in the read-only memory 4 shown in FIG. The first program is a MAIN program that is constantly executed, and its processing contents are shown in FIG. The second program is an INT program that is activated by the generation of an interrupt pulse, and its processing contents are shown in FIG. 9 and 10 will be explained in relation to FIG. 1.

When the power is turned on to the microcomputer 1, the process of step 200 in FIG. 9 is first performed to set initial values of each register and the random access memory 3 shown in FIG. Next, the key switch signal KSD, accelerator switch signal ACD, and brake switch signal BRD are taken in via the digital input circuit 12, and a key switch determination is made in step 201. If the key switch is off, step 2
02 is performed, a stop designation is performed, and the process returns to the key switch determination. When the key switch is turned on, the state of the accelerator switch is checked in the next step 203. When the accelerator is being depressed, the power running mode is specified in step 204, and the analog output ACA of the accelerator device 8 is taken in via the analog input circuit 7. on the other hand,
When the accelerator switch is in the off state, the state of the brake switch is determined in step 205. When the brake switch is off, a stop is designated and the process returns to step 202. When the brake switch is on, the regeneration mode is specified in step 205, and the
Takes in the analog output BRA of the brake device 9.

Next, in step 208, the level conversion circuit 11,
The values of the temperatures TM, TT, and TB of the motor, main thyristor, and battery are taken in through the analog input circuit 7, and if the values are abnormal, the process moves to step 209 and a protective operation is performed to reduce the current command. At the same time, an alarm is displayed on the lamp of the panel 21 via the digital output circuit 20.

Further, in step 211, the level conversion circuit 11,
The battery voltage VB is taken in through the analog input circuit 7. If the battery voltage is too low to continue operating the electric vehicle, an abnormality is determined in step 212, and steps 209 and 2 are performed.
10 protection and alarm display. Next, in step 213, the rotational speed of the electric motor is acquired via the speed detection circuit 19. If this rotational speed is abnormally high, it is determined in step 214 that overspeeding has occurred, and protection and warning display are performed. If the engine is not over-speeding, it operates normally and issues armature current commands and field current commands based on the accelerator pedal depression amount, brake pedal depression amount, and motor rotation speed detected in steps 215 and 216. After calculation, the process returns to step 202. This kind of operation is executed repeatedly in the MAIN program.

In this way, while running the MAIN program, the 5th
When the interrupt pulse shown at INP1 in the figure is input, the 10th
Execute the INT program shown in the figure. In the INT program, it is first determined whether a stop specification has been made. When a stop is specified, the process moves to step 302, where SUP is set to 0 level via the power digital output circuit 18, and the pulse of the chopper is stopped. If there is no stop instruction, step 303
Then, the armature current value IM is input into the microcomputer 1 via the analog input circuit 7. If the value is extremely large, it is abnormal, so the switch 145 shown in FIG. An alarm is displayed on the panel 21 via 20. If there is no overcurrent, step 3
07, the field current value IF is input into the microcomputer 1 via the analog input circuit 7. If this value is very large, it is abnormal, so the process moves to steps 305 and 306, and the switch 14
5 is released, an alarm is displayed, the interrupt program ends, and the program returns to the MAIN program. If there is no overcurrent, the process moves to steps 309 and 310, and the armature current command and field current command given in advance in the MAIN program and the previously detected values of the armature current IM and field current IF are Based on this, control calculations are performed to match the actually flowing current with the command value, and the conductivity values obtained as a result are set as DUA and DUF in register 11 in Figure 5.
Set to 7,118. As a result, in accordance with the set conduction rate command, the conduction rate control circuit 15, the pulse distribution circuit 16, the thyristor chopper circuit 131,
Each generates a gate pulse and a square wave for driving the base of the transistor chopper circuit 133.

These signals are amplified and the thyristors and transistors are operated to control the current flowing through the armature and field of the motor.

In the INT program shown in Figure 10, step 310
It exits when the process is finished and is always running.
Performs the action of returning to the MAIN program.

FIG. 11 shows an example of the starting sequence of these two programs in comparison with the armature chopper operation. Interrupt pulse INP1 is generated ΔT before the armature chopper's off pulse is generated, and the INT program is activated by this pulse generation. For example, after 2.0 to 2.5 msec, when the INT program ends, the operation returns to the MAIN program and is repeated. . The computer receives IM close to the peak value IP of the armature current. Note that here ΔT is 2
It is desirable to set it slightly longer than the current detection time. Detection of commutation failure may be executed in interrupt processing after the off-pulse is generated.

When an electric motor is controlled with the configuration described above, since a microprocessor is used, control performance is less likely to change due to changes in temperature and environment, and a highly reliable and compact device can be realized. Furthermore, the 11th
Generating and controlling interrupt pulses at the timing shown in the figure brings about the following effects. first, first
As can be seen from Figure 1, the current value immediately before the chopper turns off is detected, and the peak value of the current is detected and controlled, so there is less risk of commutation failure, etc., which is beneficial for protecting the motor. desirable.

Furthermore, the armature current can be detected not only directly, but also by using a signal from a shunt 149 that detects the battery current flowing through the armature, as shown in FIG. If a shunt is placed at a position such as shunt 149' in FIG. 7, the motor current will flow through the diode 142 even after the chopper is turned off, so that the armature current can be detected.

However, it is necessary to connect one end of shunt 149' to the battery's ground terminal. shant 14
Position 9 has the advantage that no special ground line is required.

Furthermore, since calculation of conduction rate in the next chopper cycle is started from the timing immediately before the chopper turns off using the previous current value, control with good responsiveness to commands and load changes is possible. Furthermore, since the current control, which has a quick response, is processed every chopper cycle, the response is even better. On the other hand, in an electric vehicle, the response after pressing the accelerator pedal is relatively slow, so the current command is calculated in the MAIN program once every few chopper cycles. Therefore, the number of processing programs in the INT program is small, and the processing time is also shortened, which has the effect that processing can be performed on a relatively slow microcomputer.

As explained above, according to the present invention, by using a method of applying an interrupt using a pulse that is synchronized with the chopper cycle and whose timing is set approximately a certain period of time before the generation of the off-pulse, it is possible to obtain control performance with good quick response. Since only the current detection control is executed by an interrupt program, the processing time is short, and even a microcomputer with relatively slow processing speed can control the electric motor.

In the embodiment, an example in which the chopper period is constant is shown, but it can be similarly applied to a variable period.
In addition, when locking the chopper's off pulse when the chopper is fully open to obtain maximum output, use the chopper control oscillator signal to generate an interrupt in synchronization with a constant cycle signal corresponding to the chopper's off pulse. All you have to do is multiply it.

Furthermore, in the control of series-wound motors, in bypass contactor closing control that short-circuits the chopper in order to obtain maximum output, the chopper is stopped when the contactor is closed, but even in this case, it is synchronized with the fixed-period signal of the chopper control oscillator. All you have to do is interrupt it.

[Brief explanation of the drawing]

1 is a block diagram showing an embodiment of an electric vehicle control device according to the present invention, FIG. 2 is a block diagram showing an embodiment of the analog input control circuit of FIG. 1, and FIG. 3 is a block diagram of an embodiment of the analog input control circuit of FIG. 4 is a circuit diagram showing an embodiment of the input circuit. FIG. 4 is a circuit diagram showing an embodiment of the interrupt circuit in FIG. 1. FIG. 5 is a circuit diagram showing an embodiment of the interrupt circuit in FIG. 1. A circuit diagram showing an embodiment, FIG. 6 is an operation waveform diagram of FIG. 5, FIG. 7 is a circuit diagram showing an embodiment of the main circuit of FIG. 1, and FIG. 8 is a diagram of the speed detection circuit of FIG. 1. A circuit diagram showing one embodiment, FIG.
Figure 10 is a flowchart of an embodiment of the INT program showing the control operations shown in Figure 1. Figure 11 is a startup sequence of the MAIN program and INT program. This is a time chart showing an example. DESCRIPTION OF SYMBOLS 1...Microcomputer, 2...Microprocessor, 8...Accelerator device, 131...Thyristor chopper circuit, 132...Shunt motor.

Claims (1)

[Scope of Claims] 1. A device that continues to supply current from a DC power supply to an electric motor according to the amount of operation of a command generation device for an accelerator pedal, which receives the motor current and the operation state of the command generation device as input, and stores it in advance in a memory. A computer that performs a logical operation on the current value to be passed through the motor according to control characteristics stored in the motor, and controls whether the chopper circuit is turned on or off based on the result, and an interrupt circuit that generates an interrupt pulse. A motor control device characterized in that it receives an interrupt pulse immediately before turning off the chopper circuit, and detects a motor current in interrupt processing. 2. The computer calculates the current command value to be applied to the motor in a constantly running program, detects the motor current in interrupt processing, and controls the motor based on the comparison between the detected value and the current command value. The electric motor control device according to claim 1, wherein the electric motor control device executes calculation of current control. 3. The motor control device according to claim 1, wherein the interrupt pulse is generated between the time when the on-pulse is generated and the time when the off-pulse is generated in the minimum conduction rate state of the chopper circuit.