JPS6031164B2 - Electric car chip control method - Google Patents

Description

[Detailed Description of the Invention] This invention maintains the conduction time of the chopper at startup to the minimum conduction time when an electric car driven by a DC motor is digitally controlled by a control device using a small computer such as a microcomputer. By gradually increasing the chopping frequency from a low frequency to the normal chopping frequency on the condition that the motor Yuka flow becomes smaller than the current limit value pattern voltage value, the continuity rate is equivalently lowered.
The inrush current is suppressed by controlling the chopper's conduction time (i.e. conduction rate) so that the current pattern follows the current pattern at a constant chopping frequency after the inrush current reaches the normal chopping frequency. This invention relates to a chopper control method that enables smooth start-up.

FIG. 1 shows the power running main circuit of a typical chopper-controlled electric vehicle.

In the figure, 1 is a current collector layer, 2, 3, 9, 18 are unit switches,
14 is a weak field contactor, 4 is a high-speed flow reducer, 5 is a flow reduction resistor, 6 is a filter reactor, 10 is an armature of a motor, 11
is a field winding, 12 is an inductive shunt, 13 is a weak field resistance, 1
5 is a main smoothing reactor, 16 is a freewheeling diode, and 17 is a chopper. The operation of this chopper main circuit is well known. Generally, chopper control is performed at a constant frequency in consideration of coordination with ground safety equipment, but due to the characteristics of thyristors, there is a limit to the minimum conductivity at a constant frequency, and when activated at a constant frequency,
There is a problem in that excessive current flows until the main motor generates a back electromotive force, causing the train to idle and making the ride uncomfortable.
The following three methods can be considered to solve this startup problem.

{i) At startup, insert a startup resistor to suppress inrush current.

'ii' As a low frequency startup method, the current conductivity is substantially reduced and inrush current is suppressed.

Wind Weaken the motor field to suppress torque even if the motor current is large.

Of these, 'i),' due to the configuration and stability of the control system.
Method ii has been in practical use for some time.

An embodiment of the starting resistance insertion method for 'i' is shown in FIG.
Components in the figure that are the same as those in FIG. 1 are designated by the same symbols. Reference numeral 7 indicates a brake converter cam switch (hereinafter referred to as cam switch), and 8 indicates a starting resistance.

In this method, the cam switch 7 is left open during startup, allowing the main circuit current to flow through the startup resistor 8, thereby suppressing rush current during startup. After a certain period of time has elapsed after startup, the cam switch 7 is turned on and normal control is started. This starting resistor insertion method requires a starting resistor 8 and a cam switch 7 compared to the main circuit in steady state as shown in Figure 1. The control circuit requires a time-limited closing circuit for the cam switch 7.

The low frequency starting method of [ii] does not require the starting resistor 8 and cam switch 7 of the starting resistor insertion method of 'i', and the main circuit during power running is as shown in FIG.

FIG. 3 shows a block diagram of an embodiment of the thyristor gate control circuit using this low frequency activation method. (This example is two-stage switching) In the figure, 20', the gate start signal 21 is the power running notch command, 22 is the variable load adjustment output, 23 is the motor current feedback amount, 24 is the reference oscillator 25, and the frequency dividing circuit 26 is the frequency switch. 27 is a phase shifter, 28 and 29 are timers, 30 is a current limit value pattern generation circuit 30, 31 is a comparison/increase calculation circuit, 32 is a thyristor gate on pulse signal, 33
is the thyristor gate off pulse signal. Generally, a crystal oscillator with a stable oscillation frequency is used as the reference oscillator 24, and the frequency is an integral multiple of the chopping frequency (hereinafter referred to as fcH). Generates a check signal. The oscillation frequency of the crystal oscillator is
Compared to fcH, this frequency is divided to fcH by the frequency dividing circuit 25 to improve the accuracy of the chopping frequency. 26 is a frequency dividing circuit with a switching function, and the timer 2 starts in synchronization with the gate start signal 20.
Detect the rising edge of the output signal of 8 and change the output frequency to fc
From H/4 to fcH/2, the rising edge of the output signal of timer 29 is detected and the output frequency is changed from fcH/2 to fc
It has the function of switching to H.

The current limit value pattern generation circuit 30 generates a current limit value pattern according to the variable load output 22 at the same time as the power running notch command 21, and inputs the pattern to the comparison increase calculation circuit 31. The comparison increase calculation circuit 31 performs comparison increase calculation on this current limit value pattern and the motor current 23 as the main circuit feedback amount, and outputs the result to the phase shifter 27 . Phase shifter 27 outputs clock signal 26
At the beginning of each cycle synchronized with , a chopper on pulse is issued and a mirror tooth wave is generated, and when this sawtooth wave becomes large due to the output of the comparison increase calculation circuit 31, an off pulse is issued to the chopper. , controls the conduction rate and thereby controls the motor current. Therefore, as shown in FIG. 4, the chopping frequency at startup is fcH for L seconds after startup until the output of the timer 28 rises.
After that, the chopping frequency is controlled at fcH/2 for t2 seconds until the output of the timer 29 rises, and after t2 seconds, it is controlled at the steady chopping frequency fcH. According to this low frequency starting method, compared to the starting resistor insertion method as mentioned above, starting resistors and cam switches are not required, and only a few new items need to be added to the gate control circuit. Miniaturization becomes possible. However, the selection of the cutting frequency is based on the steady chopping frequency fcH due to the circuit configuration.
Therefore, the chopping frequency cannot be controlled finely.

The appropriate number of switching stages is usually 1 to 3 stages, but
As mentioned above, frequency switching using this method is time-controlled by a timer regardless of the motor current, which causes the motor current to jump or drop during switching, making it difficult to control smoothly according to the current limit value pattern. Yes, it is necessary to perform a motor load test and select the optimum value for the timer setting.

As a way to eliminate this drawback, a circuit with frequency subtraction and switching functions is provided in the part corresponding to the timer circuits 28 and 29 of the frequency switching circuit 26 in FIG. 3 to more precisely control the frequency at startup. For example, if the frequency at startup is Z, fCH/8 → fCH/4 → fC
There is also a method of controlling H/3→fCH/2→public cH/3→fcH. This method also uses a timer for frequency switching timing, and is essentially the same as the method shown in Figure 3 above, which allows for relatively smooth control along the current limit value pattern compared to the method shown in Figure 3. Although this is possible, the control circuit becomes complicated due to frequency subtraction and the addition of a sliding door circuit, which is not preferable.
This invention was made in view of these points,
A chopper control device consisting of a sequence control circuit using conventional relay logic, an analog gate control circuit using obair lamp transistors, and an analog protection detection circuit is configured by a dedicated microcomputer, and when the chopper is digitally controlled, When controlling the inrush current smoothly along the current-limiting value pattern, the chopping frequency is changed while the chopper's induction time is kept at the minimum induction time, so that the motor current becomes smaller than the current-limiting value pattern voltage value. The purpose of the present invention is to provide a chopper control method for an electric vehicle that is controlled to equivalently lower the conduction rate and suppress inrush current by increasing the frequency from a low frequency to a normal chopping frequency under the following conditions.

An embodiment of the present invention shown in FIG. 5 will be described below.

In the figure, 40 to 45 are analog signals, 40 is a motor current value from a current detector (not shown), 41 is a filter capacitor voltage from a voltage detector (not shown), and 42
is the motor voltage value from another voltage detector (not shown), 4
3 is a powering eye flow value command from a variable load device (not shown); 4
Reference numeral 4 indicates a brake torque command from a brake control device (not shown), and 45 indicates a motor rotation speed obtained by frequency/voltage conversion of the output from a tacho generator (not shown). A multiplexer 46 has the function of selecting one of the five analog signals 41 to 45, and an A/D converter 47 converts the analog signal selected by the multiplexer 46 into a digital signal.

The number of bits of the digital signal is determined by the number of bits of data that can be handled by the CPU 51 used, and in the embodiment shown in FIG. 5, it is 8 bits. Note that the portion indicated by double lines in FIG. 5 indicates an 8-bit data line. Reference numeral 48 denotes an input port, which normally closes the gate of the data line and opens its own gate in response to an input command signal when an input command is received from the CPU 51, during which time the CPU 51 reads data.

Since this input command has a one-to-one correspondence with each gate, there is no possibility that the data will overlap. For example, CPU
executes the command “IN48”, input port 4
8 is opened, and the CPU 51 reads the A/D converted digital signal from the A/D converter 47 via this input port. Here, the above CPU5
1 is a central processing unit generally referred to as a CPU,
In synchronization with a clock signal of about 2 MHZ, data is read from an input port or memory, data is written to an output port or memory, and logical operations and arithmetic operations are executed according to a predetermined program. 52
is a clock generator that generates a clock with a frequency N times the chopping frequency (generally several hundred days 2), and this output is C
This is the first interrupt signal of the PU51.

Reference numeral 71 denotes a frequency divider which divides the clock signal of a clock signal generator 52 (described later) by 1/N', and its output serves as a second interrupt signal for the CPU 51.

53 is a read-only memory (ROM), and 54 is a RAM (RandomAc
cessMemory) and is a writable memory.

A program for controlling the chopper device is stored in the ROM of this memory, and the CPU 51 controls the chopper device by sequentially executing the programs stored here. The RAM 54 is a control file for the CPU 51 to determine the conduction rate of the thyristor. It is used to store temporary data when executing a zero program, or to store data when a timer mechanism is provided by increasing or decreasing the number every cycle of the chopper.

55 is a main controller, and from this main controller, forward commands, reverse commands, power running, braking commands, 1 notch, 2 notch, 3 notch, etc.
There are digital signals indicating the operating mode of the train, such as notch signals such as 4-notch signals.

57 is an input interface circuit, which converts the level of the above-mentioned digital signal (normal (DCIOOV)) to TTL, and at the same time functions to isolate the DCIOV circuit and the TTL level circuit to prevent noise from entering using relays, photocouplers, etc. The numeral 49 is the same input port as the input port 48.

56 is a high-speed current reducer of the chopper main circuit, a unit switch,
It represents the interlock signals of the brake converter, reverser, weak field switch, pre-excitation contactor, etc. These interlocks output digital signals regarding the state of the main circuit of the chopper.

Reference numeral 58 is the same input interface circuit as the input interface circuit 57, and has the functions of level conversion and insulation.

50 is the same input boat as input boats 48 and 46.

50, 60, and 61 are output ports, and data is held in each of the output ports 56 to 61 according to an output command from the CPU 51. For example, when the command ``OUT591'' is executed, the data in the nozzle register of the CPU 51 is transferred to the output port 59.
is maintained. 62 is a digital phase shifter using a counter. Simultaneously with the chopper-on command, data corresponding to the conduction rate is output from the CPU 51 to the output port 59, and at the same time, a trigger signal is given to the counter 62, and the counter 62 generates a clock signal. It automatically starts counting down in synchronization with the clock signal from the counter 63, and the counter value reaches 0.
When this occurs, a borrow signal is generated, which becomes a chopper-off signal.

The oscillation frequency of the clock signal generator 63 has M bits,
When the chopper frequency is 〆cH, it becomes 2M x nacH. In other words, if M=8, the maximum number represented by 8 bits is 1
=255, and this value corresponds to a conduction rate of 10%. Therefore, when the thin flow rate is 50%, the CPU 51 issues a chopper-on command and outputs 128 to the counter 62 at the same time.
The counter 62 starts counting down in synchronization with the clock signal (frequency cross × 〆cH) from the clock signal generator 63, and when it has counted 128 (after the on-pulse is output, the punishment for the child = T student has passed) ), a BORO signal is output, a chopper-off signal is generated, and the conduction rate is controlled to 50%. In reality, it takes about 150 ms for the chopper to turn off completely after the chopper off signal is output, so Goo 1 does not correspond to 100% conduction rate, and it takes more time to turn off than G 1. The value obtained by subtracting this amount corresponds to the conduction rate of 100%. 64 is a one-shot multi-circuit which generates a pulse only during the off pulse in response to the rise of the borrow signal from the counter 62.

67 is a gate amplifier circuit, and 69 is a commutating thyristor.

Reference numeral 65 is a one-shot multi-circuit similar to the one-shot multi-circuit 64, and generates a solid pulse only during the on-pulse.

68 is the same gate amplifier circuit as the gate amplifier circuit 67;
70 is the main thyristor 70.

66 is an output interface circuit which outputs a main circuit configuration command from the CPU 51 via the output port 61;
That is, DCIO commands such as front/rear switching commands, brake switching commands, unit position switch input, open commands, weak field switch input, open commands, pre-excitation contactor input, and open commands are executed from the TTL level.
It has the function of converting OV level and insulating at the same time.

The outline of the control by the chopper control device using the microcomputer shown in FIG. 5 is as follows.

When the control circuit power is activated by the driver's operation, the CPU5
1 reads commands from the master controller 55 via the input boat 49, and in accordance with the commands from the master controller 55, performs forward/reverse switching, power running, braking circuit configuration, turning on unit switches, etc. via the output boat 61. Controls the sequence of the main circuit. This sequence control is executed while checking the interlock signal read through the input port 5. When the configuration of the main circuit is completed, the chopper conductivity is calculated based on the pattern voltage value, motor current value, motor voltage value, and filter capacitor voltage value read through the input port 48, and the motor current is control.
If the chopper control method according to the present invention is controlled at a constant frequency ㆆcH at startup, it has the disadvantage of worsening ride comfort due to torque shock caused by rush current, as described above.In order to solve this problem, the chopper frequency at startup is limited. By comparing the relaxation pattern of the current value and the motor current, and gradually increasing the NCH from a low frequency, smooth startup is possible.

In order to suppress the inrush current, it is possible to reduce the current flow rate of the chopper, but the minimum current flow time of the chopper has a lower limit due to the characteristics of the sirens and commutation circuit used, so it cannot be reduced unnecessarily; The minimum conductivity at the frequency 'cH is generally on the order of several percent.

Therefore, at startup, if the chopper frequency is lowered while keeping the optimum conduction time at the minimum optimum conduction time, the conduction rate can be equivalently lowered. The chopper control program at startup (hereinafter referred to as the first control program) is executed in synchronization with an interrupt signal (hereinafter referred to as the first interrupt signal) from the clock generator 52 in FIG.

That is, the IZ-th control program counts the number of times the first interrupt signal is generated, and when this count reaches a set value, the count is cleared and the first control program is repeatedly executed from the beginning. The first control program first controls the main thyristor 7 through the output boat 6Z0, the one-shot multi 65, and the gate amplifier circuit 68.
After applying a 0' gate pulse and turning it on, a value corresponding to the minimum optimization time is set in the counter 62 via the output port 59. Thereafter, the counter 62 counts down the clock signal 63 to a certain extent regardless of the program, and when the minimum suitable time has elapsed, the counter 62 is turned off. - A signal is output to the one-shot multi-circuit 64, which passes through the gate amplifier circuit 67 and becomes a gate pulse for the commutating thyristor 69, firing the commutating thyristor and turning off the chopper. This allows the chopper to be controlled in the minimum optimization time. The set value of the count number can be set to any value. For example, if the set value is N, the constant chopper frequency other than during startup is set to "cH chopper cycle to Tc".
If H (TcH = 1/nacH), the first interrupt signal will interrupt with a cycle of TcH/N, and when the interrupt occurs N times, the count will reach the set value of N, so clear the count. At the same time, the chopper is turned on in the minimum suitable time. Therefore, the repetition period of the chopper is Tc
It will be controlled by H. Therefore, if the set value is N0K, the repetition period T can be made longer than TCHXN as K is increased.

At startup, the first control program sets the increment K of the set value to N to a sufficiently large value Km, which is approximately ten times as large as N.
Control is started by setting the final value of ax to N+Kmax.

As a result, the current flow rate of the chopper at startup becomes approximately one-tenth from a fraction of the chopper frequency (4) and gutter flow rate (QcH) during steady state, and inrush current can be suppressed.

If the set value is controlled at a constant value, the chopper's optimum time is constant at the minimum optimum time, so the chopper will be controlled at a constant voltage, and as the motor speed increases, the motor current will change according to the motor characteristics. is decreasing.

Therefore, in order to control the motor current according to the current limit value pattern, it is necessary to reduce the number of counts, shorten the repetition period, and increase the current flow rate of the chopper. In the first control program, after data is set to the output counter of the chopper ON command, the current limit value pattern voltage value and motor current value are transmitted via the multiplexer 46, A/D converter 47, and input port 48. Read and compare the size.

While the motor current value is greater than the pattern voltage value, control continues with the set value of the count number unchanged, and when the motor current is equal to or smaller than the pattern voltage, the set value of the count number is decreased by a fixed amount △K and repeated. Shorten the cycle to increase the chopper current and increase the motor current. The operation during this time is shown in the time chart of FIG. Figure A in Figure 6 is the first
Figure B is a diagram showing the processing time of the first control program. Figure C shows an on command, and Figure D shows an off command.
Now, the set value of the count number is 8, and the time t. When the Kawato number reaches 8 due to the interrupt processing by the first interrupt signal (the period indicated by diagonal lines in Figure B), the count number is cleared and when the interrupt processing is completed, the control program is repeatedly executed from the beginning, as shown in Figure C. Issue the on command to turn on Chita Choppa. Immediately after that, data corresponding to the minimum optimum time is set in the counter, so after the minimum optimum time has elapsed, an off signal is output as shown in Figure D, turning off the chopper. After setting data in the counter, read the current limit value pattern voltage value and the motor voltage 0 voltage value and compare their magnitude. a shown in diagram B,
, also, the period a3 corresponds to the period in which the above processing is being performed, and the period indicated by b corresponds to the "WAIT" state, which is a period in which nothing is being executed.

If the motor current is larger than the pattern voltage value by comparing T and cycles shown in Figure C, the set value remains unchanged at 8. Therefore, when the count reaches 8 due to an interrupt at the time signal, the count is cleared and the above-described operation is repeated. Comparing the motor current value and pattern voltage value in the T3 cycle, if the motor current value is equal to or smaller than the pattern pressure value, the set value of the count number is reduced by △K (in this case △K = 1) to 7. . Therefore, when the count reaches the set value of 7 due to the time interrupt, the above-described operation is repeated again. FIG. 7 shows the rate of change in conductivity with respect to the increase K in the set value of the count number. In the figure, QcH and mln indicate the minimum conduction rate when the fixed chopper frequency nCH is constant.
FIG. 8 shows the relationship between changes in motor current value and current limit value pattern voltage value and chopper frequency.

In this way, the set value of the count number, which started at N + Kmax at startup, decreases by △K and finally reaches N', the chopper frequency becomes equal to the steady state chopper frequency zocH, and from then on, the control method By switching the chopper frequency to a constant value of nacH and changing the chopper conduction time, the far current rate is controlled and the motor current is controlled in a current limit value pattern. When the chopper frequency becomes NCH, the first interrupt signal is ignored and the clock signal from the frequency divider 71 (the clock signal from the clock signal generator 52 in FIG. It is a clock signal with the same frequency as cH.) is accepted as the second interrupt signal. The second interrupt 3 interrupt signal is interrupted at the chopper period TcH, so the first
A second control program in a steady state, which is different from the control program , is repeatedly executed from the beginning each time an interrupt is generated by the second interrupt signal. 3
The second control program first issues a chopper ON command and then outputs data corresponding to the conduction rate to the counter, which is the same as the first control program, but the second control program In the program, the voltage value of the current limit value pattern 4 read after this is compared with the motor current value to determine the conduction rate. The conduction rate determined here is set in a counter at the beginning of the next cycle. The operation during this time is shown in the time chart of FIG.

A in the figure indicates the second interrupt signal from the frequency divider 71.
Figure B shows the processing time of the second control program. A is a period in which processes such as chopper-on command output, setting to the counter 62, reading of data and calculation of conductivity are performed, and b is a period in a "special" state, waiting for the next interrupt signal. . When the second interrupt occurs at the specified time, the data corresponding to the conduction rate calculated in cycle 0 before issuing the switch-on command is sent to the counter 62 as shown in Figure C.
Set to .

As described above, the counter 62 issues an off command as shown in FIG. D after the time period corresponding to the flow time has passed, and the flow rate of the chopper is controlled. Thereafter, the conductivity calculated in the T cycle is similarly outputted at the beginning of the next T2 cycle, and an OFF command is issued at time t. FIG. 10 shows a control method according to the present invention.

At startup, the first control method controls the chopper frequency while keeping the chopper optimization time constant at the minimum optimization time.
Control starts from HXN, and the chopper frequency is gradually increased while comparing the current limit value pattern and the motor current, and when the chopper frequency reaches 〆cHi at time To, from then on, the second The motor current is controlled in a current limit value pattern by controlling the chopper's optimum time using the control method while keeping the chopper frequency constant. As described above, according to the present invention, the chopper frequency is controlled while comparing the motor current value of the electric vehicle with the current limiting value pattern voltage value as a feedback amount, so that the motor current value is Smooth control along the current limit value pattern is possible without rise or fall.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing the power running main circuit of a chopper-controlled electric vehicle, Figures 2 and 3 are circuit diagrams showing a starting resistor insertion method and a low frequency starting method as conventional starting control methods, and Figure 4 is a circuit diagram showing a starting resistance insertion method and a low frequency starting method as conventional starting control methods. Fig. 3 is a time chart showing the operation of the low frequency startup method, Fig. 5 is a block diagram showing an embodiment of the present invention, Fig. 6 is a time chart for explaining the operation of the invention, and Fig. 7 is a time chart showing the operation of the low frequency startup method. FIGS. 8 and 10 are diagrams for explaining the principle of the invention, FIGS. 8 and 10 are diagrams for explaining the control system of the invention, and FIG. 9 is a time chart for explaining the operation of the invention. In the figure, 18 to 5 input boats, 51 is the CPU,
52 is a clock signal generator, 53 is ROM, 54 is RA
M, 59 to 61 are output ports, 62 is a counter, 63 is a clock generator, 64 and 65 are one-shot multi circuits, 67 and 68 are gate amplifier circuits, and 71 is a frequency divider. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. In an electric vehicle in which a DC motor is controlled by a chopper, a chopper control device is configured using a microcomputer, and a clock signal generator generates a clock signal with a frequency N times the normal chopping frequency of the chopper, which has a constant frequency. , a frequency divider 71 is provided which divides the frequency of the clock signal by 1/N, the clock signal is used as a first interrupt signal of the microcomputer, the output signal from the frequency divider is used as a second interrupt signal, and the clock signal is used as a first interrupt signal of the microcomputer. 1 interrupt signal is counted, and when the count number reaches a set value, the count number is cleared and the conduction time of the chopper is repeatedly executed while keeping the conduction time to the minimum conduction time; The second control controls the conduction time of the chopper by comparing and calculating the current limit pattern voltage value and the motor current value every time there is an interrupt signal, and the first control controls the conduction time of the chopper at startup. Control is started by setting the set value to N+K while keeping the current at the minimum conduction time, and after that, the set value is reduced by a certain amount of △K on the condition that the motor current becomes smaller than the current limit value pattern voltage value. By controlling as N + K - △K and repeating similar control, the chopping frequency is gradually increased from low frequency to the normal chopping frequency while the chopper conduction time is constant, suppressing the inrush current at startup, and increasing the motor current. is controlled according to a current limit value pattern, and when the set value reaches N, thereafter, the motor current is controlled according to the current limit value pattern by changing the chopper conduction time with a constant chopping frequency by the second control. A control method for an electric car chip characterized by: