JPS6046638B2 - Chiyotsupa control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chopper control device for regenerative braking of a drive motor in an electric vehicle or the like using a chopper.

BACKGROUND ART In electric vehicles, choppers are often used to improve the efficiency of speed control and ride comfort during power running.

Additionally, this chopper is used to perform regenerative braking during braking to reduce power consumption. In general electric vehicles, a DC series motor is often used as the drive motor, but even in this case it is desirable to perform chopper control to ensure stability from high speeds and to obtain as much braking force and regenerative power as possible. . Generally, in an electric vehicle using a DC series-wound electric crosspiece as a drive motor, in order to perform stable regenerative braking using a chopper, it is necessary to always limit the voltage generated by the motor to below the overhead line voltage.

Therefore, in order to perform regenerative braking on the motor from a high speed, it is necessary to limit the motor current or use the motor in a weak field. However, when the electric motor is controlled in this way, the braking force of the electric motor decreases, so when this braking force does not reach the required braking force for an electric vehicle, it is supplemented by air braking. In order to eliminate such inconveniences, conventional efforts have been made to increase the braking force by inserting a resistor into the motor circuit during braking to increase the voltage generated by the motor.

Generally, the resistor used in this case is short-circuited when the rotational speed of the motor decreases. However, when the resistor is short-circuited, the voltage of the filter capacitor inserted on the power supply side jumps, which may cause a sudden change in the torque of the motor or damage to the chopper. For this reason,
Measures are required to ensure that the voltage jump of the filter capacitor falls within a permissible value, and to prevent a decrease in riding comfort due to sudden changes in the torque of the motor. FIG. 1 shows a known main circuit configuration for regenerative braking that has been proposed to meet this type of requirement.

Note that in FIG. 1, a filter circuit composed of a capacitor and a reactor is actually connected to the power supply side, but this is omitted for convenience of explanation. That is, in FIG. 1, P is a pantograph that supplies power from the overhead wire T, CH is a chopper, MSL is a smoothing reactor, M is a motor, F is a motor field, BD is a blocking diode, BR is a brake resistor, and A bypass thyristor TH is connected in parallel to a series circuit of a blocking diode BD and a brake resistor BR. According to the circuit configuration shown in Fig. 1, the motor voltage exceeds the specified value in the high-speed range (AVR).
In this case, the motor voltage is controlled with the brake resistor BR inserted in series without firing the bypass thyristor TH.

Next, in the medium speed range (ACRl), the bypass thyristor TH is turned on and the conduction rate is controlled to keep the motor current constant. Furthermore, below the medium speed range (ACR2), the bypass thyristor TH is set to the maximum conduction rate to
Controls the current conduction rate and keeps the voltage value constant. In this way, the resistance value of the brake resistor BR is continuously controlled to reduce the voltage jump of the capacitor (not shown) constituting the filter circuit when the brake resistor BR is short-circuited. Sudden torque fluctuations can be avoided. The operating characteristics of the circuit described above will be explained in more detail as shown in FIGS. 2 to 5.

That is, FIG. 2 shows the operating characteristics of the chopper CH during regenerative braking. In Fig. 2, ■ on the horizontal axis. , indicates the maximum speed during braking, and V1 indicates the speed at which the voltage EM generated by the motor becomes equal to the overhead line voltage at the maximum motor current IMm~. Therefore, when applying regenerative braking at a higher speed than the speed V1, the maximum motor current is 1 Mma.
Since the motor generated voltage EM exceeds the power supply voltage Es at x, the motor current 1M is controlled to be reduced so as to always satisfy the following equation. However, EM: Motor generated voltage E,: Power supply voltage IM: Motor current RB: Brake resistance α1: Choppa's conduction rate In Fig. 2, maximum speed ■M. ．． The case where the motor current is reduced to a predetermined 1M1 at x is shown.

Note that the broken line indicates the characteristics when the brake resistor BR is not connected. On the other hand, the flow rate α of chopper CH
1 is approximately the minimum flow rate α1m1n in the range of speeds V1 to ■Max (lower than medium speed range and high speed range), and
In the range of 0 (medium speed range), the motor current ■9 is the maximum current of 1M
m. , so the minimum conductivity α1m,n
increases approximately linearly from .

In this case, the torque generated by the electric motor is constant in the speed range 0-V1'' (medium speed range and below the medium speed range), but decreases in the speed range V/~max (high speed range). ,
In the speed range V1~■1'' (lower than medium speed range), the motor current is 1M by controlling the conduction rate α2 of the bypass thyristor TH.
keep constant. FIG. 3 shows notch characteristics.

In Fig. 3, characteristic curves A and C represent brake resistor BR.
are connected, A is the characteristic when the power supply voltage is maximum, and C is the characteristic when the power supply voltage is minimum. Further, the characteristic curve shown by the broken line is the characteristic when the brake resistor BR is not connected. The range from a'' to b'' of the characteristic curve A is a high speed range (AVR) in which the bypass thyristor TH remains in the OFF state and the motor voltage is maintained at a constant value. The bypass thyristor TH fires at point b'' and starts control. In the range from b'' to point b, the conduction rate α2 of the bypass thyristor TH is controlled to keep the motor current 1M constant (maximum value IMma
．． ) is the medium speed range (ACRl). in this case,
At point b, the motor voltage 1 becomes equal to the power supply voltage, and the conduction rate α2 of the bypass thyristor TH becomes maximum. Furthermore, the range of points b to c is for a medium speed range or lower (ACR2) that controls the flow rate α1 of the chopper CH.

In addition, in FIG. 3, the range a-b of the characteristic curve opening is as follows:
High speed range (AVR) when brake resistor BR is not connected
). FIG. 4 is a waveform diagram showing the operating characteristics of the circuit shown in FIG. 1 in the medium speed range (ACRl). That is, the operation of the circuit shown in FIG. 1 will be explained based on the operating waveforms of FIG. 4. Now, when the chopper CH is turned on at time t=TO [see Fig. 4, 1, 3, and 4], the motor current 1M increases with the motor voltage [see Fig. 4, 8]. When the chopper CH is turned off at a time t equal to the minimum flow time, a motor current of 1M flows to the power supply side via the brake resistor BR and blocking diode BD connected in series, and the current flows while regenerating the power to the power supply. 1M decreases [see Figure 4, 5, 7, and 8]. Then, time t=T
When the bypass thyristor TH is turned on in step 2,
Refer to Figure 2], the current 1R flowing through the brake resistor BR
[See Fig. 4, 5] moves to the bypass thyristor TH,
The motor current 1M increases again [Fig. 4 6, 7, 8
reference〕. At this time, the motor voltage is greater than the power supply voltage.
Therefore, when the chopper CH is turned on again at time t=T3 (see FIG. 4, 1), the bypass thyristor TH is turned off (see FIG. 4, 2). Similarly, by controlling the firing timing T2 of the bypass thyristor TH, the resistance value of the brake resistor BR can be made continuously variable. In the control method described above, the resistance value RB of the brake resistor BR is determined by the following equation based on the equation (1).

However, IMl″: Maximum speed ■ Electric motor permission at Max
Maximum current capacity EMmax: Motor voltage generated at maximum allowable current of the motor at maximum speed ■Max Es. n~: Maximum value of power supply voltage α1, n: Minimum conductivity of chopper The characteristics of the motor between points a'' and b'' of characteristic curve A shown in FIG. 3 are shown in FIG.

That is, in FIG. 5, characteristic curve 1 shows the voltage-current characteristic of the motor at maximum speed. Also,
The characteristic curves ■ and ■ are the terminal voltage EcH of the chopper CH (the chopper CH operates at the minimum conduction rate α1.nin), and ■
indicates the case where the power supply voltage is maximum (Es..~), and ■ indicates the case where the power supply voltage is minimum (ESm,n). When the power supply voltage is maximum, the operating point of motor M is A, and the maximum allowable motor current 1M1'' flows, but when the power supply voltage is minimum,
Bypass thyristor TH for high speed range (AVR) control
is in the off state and the resistance value R8 of the brake resistor BR does not change, so the operating point of the motor M moves to B and the maximum allowable motor current must be reduced to IIMl''.At this time, the notch characteristic curve is as shown in Figure 3 C.Here, the maximum power supply voltage E,max is 1,650V.
1 Minimum power supply voltage Es, . If it is 1,000V,
Maximum allowable motor current 1M1″ is approximately 6 of motor current 1M1
It drops to 0% (see Figure 2). in this way,
The control method shown in FIG. 1 has the drawback that when the power supply voltage decreases, the braking current decreases, resulting in a decrease in regenerative power, and furthermore, the regenerative braking force is reduced.

Furthermore, according to the control system shown in FIG. 1, if commutation fails during high-speed braking, the motor current will become very large because no resistor is included to limit the current. Therefore, in order to coordinate overcurrent protection of the chopper and motor, it becomes necessary to add an interphase reactor to the circuit only during braking, or it is necessary to use a circuit breaker with a short operating time. Furthermore, in the control method shown in Figure 1, the motor voltage is applied to the chopper, and this voltage is nearly twice the power supply voltage, so the components that make up the chopper must be selected with this voltage in mind. Not only. The problem is that the device also becomes larger due to the higher voltage resistance. Therefore, the inventors of the present invention have conducted various studies and made prototypes in order to overcome all of the drawbacks of the chopper control device described above. As a result, the brake resistor, which is connected in series with the electric motor to the power supply, is divided into two at the connection point of the chopper. By connecting a bypass thyristor in parallel to the series circuit of a brake resistor and a blocking diode, the current flow rate of the chopper can be kept to a minimum when the voltage generated by the motor is higher than the power supply voltage, and the motor current can be kept at a specified value. By controlling the conduction rate of the bypass thyristor so that the conduction rate of the bypass thyristor reaches the maximum or a specified value, the conduction rate of the chopper is controlled so that the motor current is regulated regardless of the power supply voltage. By continuously controlling the resistance value of the brake resistor so that the brake resistor has a value of I figured it out.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a chopper control device that can increase the regeneration rate, regenerative power, and regenerative braking force without increasing the duty of the chopper with a simple circuit configuration.

In order to achieve the above object, in the present invention, a motor and a chopper are connected in parallel to a DC power supply, and a diode and a brake resistor are connected in series with the motor to the DC power supply, and the diode and brake resistor are connected in series to the DC power supply. In the chopper control device, a bypass thyristor is connected in parallel to a series circuit with a chopper, and the current rate of the bypass thyristor is controlled to perform regenerative braking of the motor. A bypass thyristor is connected in parallel to the series circuit of these divided brake resistors and diodes, and the divided circuit is connected so that the allowable motor current flows at the maximum speed and the minimum value of the power supply voltage. The present invention is characterized in that the composite resistance value of the brake resistors is set, and the conduction rate of the bypass thyristor is controlled so that the motor current or the motor terminal voltage becomes a specified value.

In the chopper control device described above, if a stabilizing resistor is connected to the motor side circuit, it is possible to increase the stability of motor drive in the event of a sudden change in power supply voltage in a high speed range where the motor voltage is higher than the high source voltage. .

Furthermore, if a short circuit switch is connected in parallel to the brake resistor and the short circuit switch shorts the brake resistor when the motor terminal voltage is below a specified value, it is possible to reduce the loss generated by the brake resistor. It is suitable.

Furthermore, even when a stabilizing resistor is connected, it is preferable to connect a shorting switch in parallel to the stabilizing resistor in the same way as described above, and to make a configuration shift to reduce the loss generated by the stabilizing resistor. next,
Embodiments of the chopper control device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 6 is a circuit diagram showing an embodiment of the chopper control device according to the present invention, in which reference numeral 10 is an overhead wire, 12 is a pantograph, 14 is a chopper, and 16 is an electric motor.

A motor field 18 and a smoothing reactor 20 are connected in series with the motor 16. Also, the electric motor 16
A blocking diode 22 and a brake resistor 24 are connected in series, and a bypass thyristor 26 is connected in parallel to the series circuit of the blocking diode 22 and brake resistor 24. Note that in the circuit shown in FIG. 6, a filter circuit consisting of a capacitor L capacitor and a reactor is actually connected to the power supply side, but
This is omitted for convenience of explanation. However, the chopper control device according to the present invention is characterized in that the brake resistor 24 is divided into two brake resistors 24a and 24b at the connection point P of the chopper 14, respectively. Next, the operating characteristics of the circuit shown in FIG. 6 will be explained below with reference to the waveform diagram shown in FIG.

Now, if the chopper 14 is turned on at time t=TO [
As the motor 16 is short-circuited via the brake resistor 24b, the motor current 1M increases [see FIG. 7 and 8]. Next, when the chopper 14 is turned off at a time t=t1 equal to the minimum conduction time, the motor current 1M flows to the power supply side via the brake resistors 24a, 24b and the blocking diode 22, regenerating the power to the power supply. However, the current 1M decreases [see Fig. 7, 5, 7, and 8]. Then, when the bypass thyristor 26 is fired at time t=T2, the brake resistors 24a, 2
The current 1R flowing through 4b is transferred to the bypass thyristor 26, and the motor current 1M increases again [Fig.
7, 8]. At this time, the motor voltage is greater than the power supply voltage. Therefore, when the chopper 14 is turned on again at time t=0 [see FIG. 7 1], the difference between the power supply voltage and the terminal voltage of the brake resistor 24a is applied to the bypass thyristor 26 in the opposite direction, and the bypass thyristor 26 is in the off state [see FIG. 7, 2]. Thereafter, by similarly controlling the firing time of the bypass thyristor 26, the resistance value of the brake resistor 24 can be continuously varied. Note that the bypass thyristor 26 has a motor current of 1M.
Alternatively, the conduction rate is controlled so that the terminal voltage of the motor 16 becomes a specified value. The above operating characteristics are substantially the same as those of the conventional chopper control device shown in FIG. 1 described above (see FIG. 4). In the chopper control device according to the present invention, the minimum power supply voltage Es. ．． , n, a resistance value such that an allowable motor current 1M1'' flows, that is, a combined resistance value RB of the brake resistors 24a and 24b.
is expressed by the following equation.

However, IMl″: Maximum speed ■ Electric motor allowance at MaO
Maximum current capacity EMmax: Motor voltage generated by the maximum allowable current of the motor at maximum speed Vmax Esmln: Minimum power supply voltage α1m1n: Minimum conductivity of the chopper By setting such a resistance value, the operating characteristics of the motor 16 are as follows. The result is as shown in Figure 8.

That is, in FIG. 8, characteristic curve 1 shows the voltage-current characteristic of the motor at maximum speed. Also,
The characteristic curves ■ and ■ are the terminal voltage EcH of the chopper 14 (the chopper 14 operates at the minimum conduction rate α1.,.), ■ indicates the case where the power supply voltage is maximum (to E, m), and ■ is the power supply voltage The case of minimum (E, min) is shown. In the present invention, in the case of the characteristic curve (■), the conduction rate α2 of the bypass thyristor 26 becomes zero, the operating point of the electric motor 16 becomes A,
As in the case where the power supply voltage is maximum (characteristic curve ■ in Figure 8),
A maximum allowable current of 1M1'' can be passed through the motor.In other words, in the conventional chopper control device, the minimum power supply voltage E
、． The characteristic curve of 1 becomes ▪ (indicated by a broken line), and the operating point of the motor also becomes B, and the motor current can be increased from IMl'' to IMl''. In addition, when the power supply voltage is maximum (E, .n~), it is necessary to have the characteristic shown in the characteristic curve ■ in Fig. 8, and in this case, the conduction rate of the bypass thyristor 26 is increased to equivalently The characteristics of In the chopper control device according to the present invention, the notch characteristics are as shown in characteristic curve 2 in FIG. 9 regardless of the power supply voltage.

Characteristic curves A and C shown in FIG. 9 are notch characteristics of the conventional chopper control device, where A shows the case where the power supply voltage is maximum and curve C shows the case where the power supply voltage is the minimum. As is clear from FIG. 9, the device of the present invention can increase the motor current at high speeds compared to the conventional device, so it is possible to improve the braking force, regenerated power, and regeneration rate. Also, if supplementary air braking is required, the proportion of that burden can be reduced. In particular, as the power supply voltage becomes lower, the above effect becomes even greater. 10 to 13 show different embodiments of the chopper control device according to the present invention.

That is, FIG. 10 shows the circuit configuration shown in FIG. 6 in which a stabilizing resistor 28 is inserted and connected. By inserting the stabilizing resistor 28 in this way, it is possible to increase the stability of driving the motor when the power supply voltage suddenly changes in a high speed range where the motor voltage is higher than the power supply voltage. 11th
The figure shows the circuit configuration shown in FIG. 6 in which a shorting switch 30 is connected in parallel to the brake resistors 24a and 24b.

With this configuration, if the brake resistors 24a and 24b are short-circuited when the bypass thyristor 26 reaches the maximum conduction rate and under certain conditions during regenerative braking, the loss generated by the brake resistors 24a and 24b can be reduced. can do. FIG. 12 shows each brake resistor 24a, 24b and the ballast resistor 2 in the circuit configuration shown in FIG.
Short-circuit switches 32, 34, and 36 are connected in parallel to the brake resistors 24a, 24b, and the stabilizing resistor 28, respectively, in the same manner as in the previous embodiment to reduce the loss generated by the brake resistors 24a, 24b and the stabilizing resistor 28.

In this case, as shown in FIG. 13, it is also possible to configure the shorting switches 32 and 34 with a single shorting switch 32. In the embodiments shown in FIGS. 11 to 13, the shorting switches 30, 32, 34, and 36 are each exemplified as mechanical switches, but it is of course possible to use semiconductor switches such as thyristors.

As is clear from the embodiments described above, the chopper control device according to the present invention has various advantages over conventional devices, and these can be summarized as follows.

(1) Since the motor current can flow up to the maximum allowable value regardless of the power supply voltage, it is possible to increase regenerative braking force, regenerative power, and regeneration rate.

(2) If the regenerative braking force alone is insufficient in braking force and air braking is supplemented, the air braking force can be reduced and maintenance costs etc. can be reduced.

(3) Especially when the power supply voltage is low, the above (1) and (2)
The effect is large. (4) Even if the chopper fails to commutate during high-speed regenerative braking, the motor current is limited because a resistor (brake resistor) is inserted in the circuit, facilitating overcurrent protection coordination.

(5) Since the voltage applied to the chopper during regenerative braking is lower than the motor voltage, the chopper device can be made smaller.

Since the chopper control device according to the present invention regenerates power from a DC motor to a DC power source, it can be suitably applied not only to electric cars and electric vehicles, but also to all other semiconductor converters. The above-mentioned effects can be expected when the present invention is applied to a device that performs regeneration control by interposing a chopper in a DC intermediate circuit.

Although the case of a single-phase single chopper has been described above as a preferred embodiment of the present invention, the present invention is not only applicable to a multi-phase multiplex chopper, but also has other applications within the scope of the spirit of the present invention. Of course, various design changes can be made within the structure.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram showing the main circuit configuration of a conventional chopper control device, Fig. 2 is an operating characteristic curve diagram during regenerative braking of the circuit shown in Fig. 1, and Fig. 3 is a regenerative braking diagram of the circuit shown in Fig. 1. A notch characteristic curve diagram during braking, Figure 4 is an operating waveform diagram of the circuit shown in Figure 1, Figure 5 is an operating characteristic curve diagram of the motor when it has the notch characteristic shown in Figure 3, and Figure 6 is a diagram of the operating characteristic curve of the circuit shown in Figure 1. A main circuit configuration wiring diagram showing an embodiment of the chopper control device according to the invention, FIG. 7 is an operating waveform diagram of the circuit shown in FIG. 6, and FIG. 8 is an operating characteristic curve diagram of the motor of the circuit shown in FIG. , FIG. 9 is a notch characteristic curve diagram during regenerative braking of the circuit shown in FIG. 6, and FIGS. 10 to 13 are main circuit configuration wiring diagrams showing different embodiments of the chopper control device according to the present invention. be. 10... Overhead wire, 12... Pantograph,
14...Chopper, 16...Electric motor, 18
...Motor field, 20...Smoothing reactor, 22...Blocking diode, 24.
... Brake resistor, 26 ... Bypass thyristor, 28 ... Stability resistor, 30, 32, 34,
36...Short switch.

Claims (1)

[Claims] 1. A motor and a chopper are connected in parallel to a DC power source, and a diode and a brake resistor are connected in series with the motor to the DC power source, and a series circuit of the diode and the brake resistor is connected to the DC power source. In a chopper control device configured to connect bypass thyristors in parallel and control the conduction rate of the bypass thyristor to perform regeneration control of a motor, the brake resistor is connected to a DC power supply side circuit and a motor side circuit with respect to the chopper. A bypass thyristor is connected in parallel to the series circuit of these divided brake resistors and diodes, and the divided brake resistors are connected in parallel so that the permissible motor current flows at the maximum speed and the minimum value of the power supply voltage. 1. A chopper control device that sets a combined resistance value of and controls a conduction rate of a bypass thyristor so that a motor current or a motor terminal voltage becomes a specified value. 2. The chopper control device according to claim 1, wherein a stabilizing resistor is connected to the motor side circuit. 3. In the chopper control device according to claim 1, a shorting switch is connected in parallel to the brake resistor, and the shorting switch short-circuits the brake resistor when the motor terminal voltage is below a specified value. Chopper control device. 4. The chopper control device according to claim 2, wherein a shorting switch is connected in parallel to the stabilizing resistor, and the shorting switch short-circuits the stabilizing resistor when the motor terminal voltage is below a specified value. Chopper control device.