JPS6046639B2 - 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 speed control efficiency 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 source, 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. It will be done. Generally, in an electric vehicle using a DC series motor 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 wire voltage.

Therefore, in order to perform regenerative braking on the J 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, air braking is used to supplement it. In order to eliminate such inconvenience,
Conventionally, when braking, a resistor is inserted into the motor circuit,
Efforts have been made to increase the braking force by increasing 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 and the
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, V on the horizontal axis. ．． aO indicates the maximum speed during braking, and V1 indicates the maximum motor current IM. ．． ax indicates the speed at which the voltage becomes equal to the overhead wire voltage. Therefore, the speed V
When applying regenerative braking at a higher speed than 1, the maximum motor current 1
Mm. 8, the motor generated voltage EM exceeds the power supply voltage Es, so the motor current 1 is adjusted so that the following equation is always satisfied.
M is controlled to be reduced. However, EM: Motor generated voltage E,
: Power supply voltage IM: Motor current RB: Brake resistance α1 : Current flow rate of the chopper In Fig. 2, maximum speed V. The case is shown in which the motor current is reduced to a predetermined value of 1M1 at nax.

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 the speed V1 to V.1. ．． In the range of ax (lower than medium speed range and high speed range), the flow rate is approximately small α1. nin, and the speed V1
~O range (medium speed range), motor current 1M is maximum current 1
Since the control is performed so that Mmax, the minimum conductivity α1. ．．
increases approximately linearly from in.

In this case, the torque generated by the electric motor is constant in the speed range 0-V1'' (middle speed range and below the middle speed range), but decreases in the speed range V/~V.n~ (high speed range). Also,
In the speed range V1 to V1'' (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 opening indicated by a 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 constant (maximum value IM...a
x) is the medium speed range (ACRl). in this case,
At point b, the motor voltage V1 and the power supply voltage become equal, and the conduction rate α2 of the bypass thyristor TH becomes maximum. Furthermore, the range of points b-c is a case where the flow rate α1 of the chopper CH is controlled at a medium speed range or lower (ACR2).

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 after a time t equal to the minimum flow time, the motor current 1M flows to the power supply side via the brake resistor BR and blocking diode BD connected in series, and the current is increased 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■.

Maximum permissible motor current EMO.

,: Maximum speed■. . , the motor voltage generated at the maximum allowable current of the motor Es. ~: Maximum value of power supply voltage α1min: Minimum conductivity of chopper The characteristics of the motor between points a'' and b'' of the 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., n), ■ shows the case of the maximum power supply voltage (Es...-), and ■ shows the case of the power supply voltage The case where the voltage is minimum (E, min) is shown. 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 RB 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 IMl''.At this time, the notch characteristic curve is as shown in Figure 3 C.Here, the maximum power supply voltage E,.n is 1,650cm,
Minimum power supply voltage ES. ．． If in 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 method shown in FIG. 1, if commutation fails during high-speed braking, the motor current becomes very large because there is no resistance 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 can you hear it. The problem is that the device also becomes larger due to the higher voltage resistance. In order to overcome all the drawbacks of the chopper control device mentioned above, the inventors of the present invention conducted various studies and made prototypes, and as a result, they connected the 7 brake resistors connected in series with the electric motor to the power supply so that they were connected in parallel with the chopper. death,
By connecting a bypass thyristor in parallel to the series circuit of this brake resistor and blocking diode,
It prevents the chopper voltage from exceeding the power supply voltage even when the voltage generated by the motor is higher than the power supply voltage, and also keeps the current flow rate of the chopper to a minimum when the voltage generated by the motor exceeds the power supply voltage, and also reduces the motor current. The conduction rate of the bypass thyristor is controlled to a specified value, and after the conduction rate of the bypass thyristor reaches the maximum or a specified value, the conduction rate of the chopper is controlled, and the conduction rate of the chopper is controlled so that it becomes a specified value. By continuously controlling the resistance value of the brake resistor so that the motor current becomes a specified value without any problem, the regeneration rate, regenerative power, and regenerative braking force during regenerative braking of the motor can be increased, and the above-mentioned problems can be solved. I found out that it can be solved in one go.

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 a chopper control device configured to connect a bypass thyristor in parallel to a series circuit with a motor and control the conduction rate of the bypass thyristor to perform regenerative braking of an electric motor, the brake resistor is connected to a circuit on the motor side of the chopper. A diode connected in series with the brake resistor is provided in the DC power supply side circuit of the chopper, a bypass thyristor is connected in parallel to the brake resistor and the diode, and a short circuit switch is connected in parallel to the brake resistor. The composite resistance value of the brake resistor is set so that the allowable motor current flows at the maximum speed and the minimum power supply voltage, and the conduction rate of the bypass thyristor is controlled so that the motor current or motor terminal voltage becomes a specified value, and the motor Short circuit occurs if the terminal voltage is below the specified value. The brake resistor is configured to be short-circuited by the inch.

In the above-mentioned chopper control device, if a stabilizing resistor is connected to the motor side circuit, it will be possible to prevent sudden changes in the power supply voltage in high-speed range where the motor voltage is higher than the power supply voltage. It becomes possible to increase the stability of driving the electric motor.

In this case, connect a shorting switch in parallel to the ballast resistor,
If this switch is operated in the same manner as the short circuit switch of the brake resistor, it is possible to reduce the loss caused by the stabilizing resistor.

Next, embodiments of a 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 the basic configuration of a 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, for the power supply, the electric motor 1
A blocking diode 22 and a brake resistor 24 are connected in series with the blocking diode 6, and a bypass resistor 26 is connected in parallel to the series circuit of the blocking diode 22 and the brake resistor 24. in this case,
The present invention is characterized in that the chopper 14 is connected and arranged between the connection point P between the blocking diode 22 and the brake resistor 24 and the negative side of the power supply. Note that in the circuit shown in FIG. 6, 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. 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 [
Since the motor 16 is short-circuited via the brake resistor 24, 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 resistor 24 and the blocking diode 22, and the electric current is regenerated into the power supply. 1M decreases [see Figure 7, 5, 7, and 8]. Next, when the bypass thyristor 26 is ignited at time t=, the current 1R flowing through the brake resistor 24 decreases.
is transferred to the bypass thyristor 26, and the motor current 1M increases again [see Fig. 7, 6, 7, and 8]. At this time,
Greater than motor voltage. Therefore, when the chopper 14 is turned on again at time t=T3 (see FIG. 7 1), the bypass thyristor 26 receives the power supply voltage and the brake resistor 24.
A difference with the terminal voltage of a is added in the opposite direction, and the bypass thyristor 26 is turned off (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. In addition, bypass thyristor 2
6 controls the conduction rate so that the motor current of 1M or 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 brake resistors 24a, 24 have a resistance value such that at the maximum speed and the minimum power supply voltage ESmin, the allowable motor current
The combined resistance value RB of b is expressed by the following equation.

However, IMl'': Maximum speed■.Electric motor permission at AO
Capacity maximum current EMmax: Motor voltage generated at maximum allowable motor current at maximum speed Vmax ESmin: Minimum power supply voltage α1. nin: Minimum conductivity of the chopper By setting such a resistance value, the operating characteristics of the motor 16 become as shown in FIG.

That is, in FIG. 8, characteristic curve 1 shows the voltage-current characteristic of the motor at maximum speed. Also,
Characteristic curves ■ and ■ are terminal E of chopper 14. H (the chopper 14 operates at a minimum conduction rate α1m,n), ■ indicates the case where the power supply voltage is maximum (EsmaO), and ■ indicates the case where the power supply voltage is minimum (E, min). 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 motor 16 becomes A, and when the power supply voltage is maximum (characteristic curve ■ in FIG. 8). In other words, in the conventional chopper control device, the minimum power supply voltage Esm
, n 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, 7.,), the characteristic curve ■
In this case, the conduction rate of the bypass thyristor 26 is increased to equivalently obtain the characteristic shown in (2). 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, and thus can improve 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 12 show different embodiments of the chopper control device according to the present invention.

In other words, Fig. 10 shows the circuit configuration shown in Fig. 6 in which the stabilizing resistor 28 is inserted and connected. By inserting the stabilizing resistor 28 in this way, the motor voltage is higher than the power supply voltage at high speed. The stability of the motor drive can be increased when the power supply voltage suddenly changes in the region.
The figure shows an embodiment of the present invention in which a shorting switch 30 is connected in parallel to the brake resistor 24 in the circuit configuration shown in FIG.

With this configuration, by short-circuiting the brake resistor 24 when the bypass thyristor 26 reaches the maximum conduction rate and under certain conditions during regenerative braking, it is possible to reduce the loss generated by the brake resistor 24. . Figure 12 shows
In the circuit configuration shown in FIG.
Short circuit switches 30 and 32 are connected in parallel to the stabilizing resistor 28, and the brake resistor 24 is connected in parallel to the stabilizing resistor 28, respectively.
Also, the loss generated by the stabilizing resistor 28 is reduced.

In the embodiments shown in FIGS. 11 and 12 described above, the shorting switches 30 and 32 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 in Yanghe, where the power supply voltage is low,
) has a large effect. (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 if the present invention is applied to a device in which a chopper is interposed in a DC intermediate circuit to perform regeneration control.

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.

[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. 7 is an operating waveform diagram of the circuit shown in FIG. 6, and FIG. 8 is an operating characteristic curve of the motor of the circuit shown in FIG. 6. 9 is a notch characteristic curve diagram during regenerative braking of the circuit shown in FIG. 6, and FIGS. 10 to 12 are main circuit configuration wiring diagrams showing different embodiments of the chopper control device according to the present invention. 10... overhead wire, 12... pantograph,
14...Chopper, 16...Electric motor, 1
8...Motor field, 20...Smoothing reactor, 22...Blocking diode, 2
4... Brake resistor, 26... Bypass thyristor, 28... Stability resistor, 30, 32
...Short switch.

Claims (1)

[Claims] 1. 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 the brake resistor are connected in a series circuit. In a chopper control device configured to connect bypass thyristors in parallel and perform regenerative braking of an electric motor by controlling the conduction rate of the bypass thyristors, the brake resistor is connected to a motor side circuit for the chopper, and the brake resistor is connected to a circuit on the electric motor side of the chopper. A diode connected in series with the brake resistor is installed in the DC power supply circuit for the chopper, and a bypass thyristor is connected in parallel to the brake resistor and the diode.A short-circuit switch is connected in parallel to the brake resistor to minimize the power supply voltage at maximum speed. The composite resistance value of the brake resistor is set so that the allowable motor current flows at the specified value, and the conduction rate of the bypass thyristor is controlled so that the motor current or motor terminal voltage becomes the specified value, and the motor terminal voltage is less than or equal to the specified value. A chopper control device configured to short-circuit a brake resistor by means of a short-circuit switch. 2. The chopper control device according to claim 1, wherein a stabilizing resistor is connected to the motor side circuit. 3. 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.