POWER CONTROL OF TRANSPORT SYSTEM
Field of the invention
The object of the invention is a rectifier of the intermediate circuit power as
defined in the preamble of claim 1, a power control of a transport system as
defined in the preamble of claim 2, and a method for controlling the power of a
transport system as defined in the preamble of claim 10.
Prior art
In a transport system power is supplied to the motor for moving the transport
appliance. Power supply to the motor generally occurs by means of an inverter.
When braking the transport appliance, power also returns from the motor to the
DC intermediate circuit of the inverter, where it is often converted into heat,
especially in low-power systems, in a separate power resistor. There are also
applications in which the braking power of the motor is returned to the network
by means of a mains AC rectifier. In this case a separate, application-specific
appliance for handling braking power is fitted in connection with the inverter.
The power resistor that consumes braking power is conventionally fitted to the
DC intermediate circuit of the inverter via a controlling switch, i.e. a brake
chopper, between the positive and the negative intermediate circuit busbar, e.g.
in the manner presented in Fig. 1. When the switch is conducting, the power
resistor consumes the intermediate circuit power as heat. When the motor
brakes, the intermediate circuit voltage starts to rise, and resistor braking starts
up when the voltage has reached a limit value, which can be as much as 700
volts. In this case the voltage endurance of the power resistor must be
dimensioned in accordance with the intermediate circuit voltage.
During resistor braking the current and the voltage of the power resistor vary
according to the switching frequency of the brake chopper, and the speeds of
changes in the current and voltage roughly correspond to the rise and fall times
of the switch of the brake chopper. This kind of great speed of change in the
voltage and current produces high-frequency EMC disturbances, which must be
taken into account in designing the interference suppression of the appliance. In
this case special protectively screened cable must generally be used in the
supply cables of the power resistor.
Purpose of the invention
The purpose of this invention is to solve the aforementioned problems of prior
art as well as the problems presented in the description of the invention below.
Thus a rectifier of the intermediate circuit power is presented in the invention, by
means of which the supplied load can be controlled more versatilely than in
prior art.
Characteristic features of the invention
The rectifier of the intermediate circuit power according to the invention is
characterized by what is disclosed in the characterization part of claim 1. The
power control of a transport system according to the invention is characterized
by what is disclosed in the characterization part of claim 2. The method
according to the invention for controlling the power of a transport system is
characterized by what is disclosed in the characterization part of claim 10. Other
features of the invention are characterized by what is disclosed in the other
claims. Some inventive embodiments are also discussed in the descriptive
section of the present application. The inventive content of the application can
also be defined differently than in the claims presented below. The inventive
content may also consist of several separate inventions, especially if the
invention is considered in the light of expressions or implicit sub-tasks or from
the point of view of advantages or categories of advantages achieved. In this
case, some of the attributes contained in the claims below may be superfluous
from the point of view of separate inventive concepts.
The power supply appliance of the intermediate circuit according to the
invention can be e.g. a single-phase or a multiphase inverter. The power supply
appliance of the motor according to the invention can be a controller of an AC
motor, such as a frequency converter or on the other hand the power supply
appliance can comprise e.g. a power rectifier of an H-bridge DC motor.
The transport system referred to in the invention can be, for instance, an
elevator system, an escalator system, a travelator system or a crane system. A
transport appliance refers in this context to a part of a transport system that is
used to move the transported load, such as passengers or goods.
The rectifier of intermediate circuit power according to the invention contains
interfaces to the intermediate circuit of the power supply appliance as well as to
the supplied load. The aforementioned power supply appliance of the
intermediate circuit contains interfaces to a first power source as well as to a
second power source. The aforementioned rectifier of the intermediate circuit
power contains a control, in which is an input for the signal indicating the power
supply of the second power source. The control is fitted to control the rectifier of
the intermediate circuit power in response to the aforementioned signal
indicating the power supply of the second power source, for supplying to the
load the power transmitted to the intermediate circuit from the second power
source. The aforementioned rectifier of the intermediate circuit power is single-
phase, comprising a choke as well as a changeover switch. The choke is fitted
between the first connection point of the supplied load and the output of the
changeover switch, at least two capacitors in series are connected in parallel
with the changeover switch, and the second connection point of the supplied
load is connected between the capacitors.
The aforementioned signal indicating the power supply of the second power
source can comprise e.g. data about some electrical magnitude of the power
supply appliance of the second power source or of the intermediate circuit, such
as about the voltage, current or instantaneous power.
The aforementioned first power source can be, for instance, an electricity
network or a generator.
The aforementioned second power source can be, for instance, a generator, a
motor, an accumulator, a supercapacitor, a fuel cell, or the power supply of a
solar panel.
The power control of a transport system according to the invention comprises
an electric motor for moving the transport appliance as well a power supply
appliance of the motor, which comprises an intermediate circuit and which
power supply appliance of the motor is fitted between the power source and the
electric motor. The power control further comprises a single-phase rectifier of
the intermediate circuit power, which single-phase rectifier of the intermediate
circuit power is fitted between the intermediate circuit of the power supply
appliance of the motor and the supplied load, for supplying onwards to the load
the power returning to the intermediate circuit from the electric motor. The
single-phase rectifier of the intermediate circuit power comprises a choke as
well as a changeover switch. The choke is fitted between the first connection
point of the supplied load and the output of the changeover switch of the
rectifier of the intermediate circuit power, at least two capacitors in series are
connected in parallel with the changeover switch, and the second connection
point of the supplied load is connected between the capacitors. The
aforementioned power source can be, for instance, an electricity network or a
generator.
In one power control according to the invention the rectifier of the intermediate
circuit power is fitted to supply power from the intermediate circuit of the power
supply appliance of the motor to a phase of the electricity network.
One power control according to the invention comprises at least two
aforementioned single-phase rectifiers of the intermediate circuit.
In one embodiment of the invention three aforementioned single-phase rectifiers
of the intermediate circuit power are fitted to the power control of the transport
system, for supplying power from the intermediate circuit of the power supply
appliance of the motor to a three-phase electricity network. In this case each of
the aforementioned single-phase rectifiers of the intermediate circuit power is
connected to a different phase of the aforementioned three-phase electricity
network.
In one power control according to the invention the rectifier of the intermediate
circuit power can be controlled according to the load connected. The control of
the rectifier of the intermediate circuit power can in this case vary depending on
the supplied load, and the current supplied and the frequency of the voltage can
change. With the control of the rectifier it is possible to implement e.g. a supply
voltage at the generally used 50 hertz frequency and with a nominal value of
230 volts, in which case different loads connected to a normal 230 volt
electricity network can be supplied with the rectifier of the intermediate circuit
power. The frequency of the supply voltage can, if necessary, also be increased
and e.g. a transformer can be supplied with this higher-frequency voltage, in
which case the power density of the transformer is greater than with
conventional 50 hertz transformers.
In one power control according to the invention the supplied load comprises a
power resistor.
In one power control according to the invention the supplied load comprises a
power supply of the electrification of a transport system.
In one power control according to the invention the positive and negative
changeover contacts of the rectifier of the intermediate circuit power can be
controlled into a conductive state simultaneously for dynamic braking of the
motor.
In one power control according to the invention the rectifier of the intermediate
circuit power comprises a definition of the power to be supplied to the load.
One rectifier of the intermediate circuit power according to the invention
comprises a measurement of the current of the load, and the status of the load
is in this case estimated on the basis of the measured current.
In the method according to the invention for controlling the power of a transport
system a power supply appliance of the motor is fitted between the power
source and the electric motor; a single-phase rectifier of intermediate circuit
power is fitted between the intermediate circuit of the power supply appliance
and the supplied load; a changeover switch is fitted in the single-phase rectifier
of the of the intermediate circuit power; a choke is fitted between the output of
the changeover switch and the first connection point of the supplied load; at
least two capacitors in series are connected in parallel with the aforementioned
changeover switch; and also a second connection point of the supplied load is
connected between the capacitors.
In one method according to the invention for controlling the power of a transport
system the intermediate circuit voltage is measured; the power supply from the
intermediate circuit to the supplied load is started after the intermediate circuit
voltage has exceeded the limit value of voltage; and also the power supply from
the intermediate circuit to the supplied load is stopped after the intermediate
circuit voltage has fallen below the limit value of voltage.
In one power control according to the invention the rectifier control comprises a
first and a second limit value of intermediate circuit voltage, of which the first
limit value is greater than the second limit value. The rectifier of the intermediate
circuit power is in this case fitted to start the power supply from the intermediate
circuit to the supplied load after the intermediate circuit voltage has exceeded
the first limit value and to stop the power supply from the intermediate circuit to
the supplied load after the intermediate circuit voltage has fallen below the
second limit value. In other words, in this case the first and the second limit
value form hysteresis limits for the starting and the stopping of the power
supply.
In another power control according to the invention the rectifier control
comprises only one limit value. The rectifier of the intermediate circuit power is
in this case fitted to start the power supply from the intermediate circuit to the
supplied load after the intermediate circuit voltage has exceeded the limit value
and to stop the power supply after the intermediate circuit voltage has fallen
below the limit value.
In one embodiment of the invention a wire is connected between the capacitors
of the rectifier of the intermediate circuit power, the other end of which is
connected to the second connection point of the supplied load. In one
embodiment of the invention at least one interference filtering choke is
connected in series with the aforementioned wire for filtering interference
caused by the rectifier of the intermediate circuit power. The aforementioned
choke can be an RF choke, in which case it is used for filtering only high-
frequency, over 150 kilohertz, interference. The choke can also be intended for
filtering lower-frequency interference, such as changes in the current of the
switching frequencies of the rectifier of the intermediate circuit power. It is also
possible that the choke connected in series with the lead between the output of
the changeover switch of the rectifier of the intermediate circuit power and the
first connection point of the supplied load is divided into two parts, and the
second of the aforementioned chokes is fitted in place of the interference
filtering choke or in series with the interference filtering choke. In one
embodiment of the invention the interference filtering also comprises at least
one capacitor.
In one power control according to the invention a controllable switch, which is
fitted to close when the intermediate circuit voltage has reached a pre-
determined limit value, is fitted in series with at least one choke. The pre-
determined limit value can be, for instance, 350 volts.
In one power control according to the invention the rectifier of the intermediate
circuit power comprises a rectifier control, which comprises a reference value of
the current of the supplied load formed on the basis of the measurement of the
intermediate circuit voltage. The rectifier of the intermediate circuit power is in
this case fitted to adjust the current of the load to be connected according to the
reference value with the rectifier control.
The supplied load can comprise an accumulator set and/or a supercapacitor, or
the charging device of these.
In one embodiment of the invention IGBT transistors are preferably used as the
changeover contacts of the changeover switches of the rectifier of the
intermediate circuit power.
In one embodiment of the invention the aforementioned single-phase rectifier of
the intermediate circuit power is integrated into the aforementioned power
supply appliance of the motor. In this case at least a part of the main circuit of
the rectifier of the intermediate circuit power, such as the changeover switch
and the capacitors, is integrated into the main circuit of the power supply
appliance of the motor, e.g. onto the same circuit board. It is also possible that
the control of the single-phase rectifier of the intermediate circuit power is
integrated into the control of the power supply appliance of the motor, in which
case it can be implemented e.g. on the same microprocessor.
Advantages of the invention
With the invention at least one of the following advantages, among others, is
achieved:
- With the rectifier of the intermediate circuit power it is possible to supply
intermediate circuit power, such as braking energy returning from the
motor of the transport system, to different loads to be supplied. The
supplied load can be diversely selected, and the rectifier of the
intermediate circuit power can be controlled according to the load
connected. The supply voltage and the current of the supplied load can
in this case be fitted on the basis of the supplied load, in which case the
frequency and amplitude of the current and the voltage can be selected
according to the dimensioning of the supplied load. When the variation of
the switching frequency of the current and voltage of the supplied load
diminishes, it is also possible to manage with less interference protection
than in prior art.
- When the power resistor that consumes the braking power of the motor
is supplied with the rectifier of the intermediate circuit power according to
the invention, the supply voltage of the power resistor can be selected
according to the voltage endurance of the resistor, in which case it is
possible to select, for instance, the generally used resistors dimensioned
for a voltage endurance of 230 volts as the power resistor.
- When the power supply of the electrification of the transport system
occurs via the rectifier of the intermediate circuit power, the braking
power of the motor can be used as an energy source of the electrification
of the transport system, in which case the efficiency ratio of the transport
system improves.
- The rectifier of the intermediate circuit power according to the invention
can also, if necessary, be fitted to supply power to the electricity network,
in which case the braking power of the motor can be returned back to the
network, and the efficiency ratio of the transport system improves.
- By means of the rectifier of the intermediate circuit power it is also
possible to implement so-called dynamic braking, in which case the
positive and negative changeover contact of the rectifier are controlled
into a conductive state simultaneously. In this case the source voltage
produced in the phases of the motor by the movement of the motor short
circuits via the serial connection of the changeover contacts of the
rectifier of the intermediate circuit power, and the short circuit current
brakes the movement of the motor.
- The rectifier of the intermediate circuit power can also determine the
power of the supplied load e.g. by means of the voltage and current of
the load. In this case on the basis of the input power the rectifier can e.g.
estimate the warming of the power resistor functioning as the supplied
load, and determine any overheating of the resistor, in which case the
operation of the transport system can if necessary be stopped when the
safety of the transport system is endangered.
- The status of the supplied load can be estimated from the measurement
of the current of the supplied load. For example, a poor connection of the
supply cables of the power resistor can be detected as an interruption of
the passage of current, in which case the operation of the transport
system can be halted. Fault data about malfunctioning of the load can
also if necessary be sent to the service center.
Presentation of drawings
In the following, the invention will be described in more detail by the aid of a few
examples of its embodiments with reference to the attached drawings, wherein
Fig. 1 presents a power control of a transport system according to prior
art
Fig. 2 presents a power control of a transport system according to the
invention
Fig. 3 presents a rectifier of the intermediate circuit power according to
the invention
Fig. 4 presents a rectifier control as a block diagram
Fig. 6 presents an embodiment of the invention, which contains three
single-phase rectifiers of the intermediate circuit power
Fig. 7 presents an embodiment of the invention, in which a power supply
of a solar panel is fitted
Fig. 1 presents a power control of a transport system according to prior art. The
frequency converter 3 comprises a rectifier 8, a DC intermediate circuit 4,5 and
an inverter 9. The rectifier 8 converts the three-phase voltage of the electricity
network 6 into DC voltage to the DC intermediate circuit, and the inverter 9
further converts the voltage of the DC intermediate circuit into the variable
frequency and variable amplitude supply voltage of the motor. Power supply by
means of the frequency converter according to Fig. 1 is possible only from the
electricity network 6 towards the motor 2. In the transport system during motor
braking, however, power also returns from the motor back to the DC
intermediate circuit 4,5 and in this case the power is consumed in the power
resistor 15 as heat. When the power starts to return from the motor to the
intermediate circuit, the intermediate circuit voltage starts to rise. The frequency
converter 3 registers the rise in voltage, and connects the switch 20, i.e. the
brake chopper, into a conductive state. In this case the power resistor 15
connects between the positive 4 of the DC intermediate circuit and the negative
intermediate circuit busbar, and current starts to travel in the power resistor 15.
This so-called resistor braking can start e.g. after the intermediate circuit
voltage has risen to 700 volts, in which case the power resistor 15 must be
dimensioned to withstand this kind of high intermediate circuit voltage.
Fig. 2 presents a power control of a transport system according to the invention.
In this embodiment of the invention the transport system is an elevator system,
but a corresponding power control is also suited to many different transport
systems. In this context the power supply appliance 3 of the elevator motor is a
frequency converter, comprising a rectifier 8, an intermediate circuit 4,5 and an
inverter 9. The frequency converter 3 supplies power from the electricity
network 6 to the motor 2 that moves the elevator car (not shown in the figure).
The power control also comprises a rectifier 7 of the intermediate circuit power,
which is fitted between the intermediate circuit 4,5 of the power supply
appliance of the motor and the supplied load 14. In this context the supplied
load 14 is the power resistor, but the load can also be e.g. the power supply of
the electrification of an elevator system, in which case it is possible to supply
the intermediate circuit power of the frequency converter e.g. to the control
electronics of the elevator, to the electrification of the elevator shaft or to the
lighting of the elevator. Since power returns from the elevator motor 2 to the DC
intermediate circuit 4,5 during generator operation of the elevator, the returning
power can in this case be utilized in the electrification of the elevator system, in
which case the efficiency ratio of the elevator system improves. The rectifier 7
of the intermediate circuit power can also be fitted to supply power from the
intermediate circuit 4,5 of the frequency converter to a phase of the electricity
network 6.
The rectifier 7 of the intermediate circuit power comprises a rectifier control 29,
with which the power from the intermediate circuit 4,5 of the frequency
converter to the supplied load 14 is controlled. The rectifier control starts up
after the intermediate circuit voltage has risen above the pre-determined first
limit value 38, and stops after the intermediate circuit voltage has fallen below
the second pre-determined limit value 39. In other words, the limit values form
hysteresis limits for the rectifier control, in which case it is not possible that with
a certain value of intermediate circuit voltage the control would start to switch on
and off at a high frequency.
Fig. 3 describes a rectifier 7 of the intermediate circuit power according to the
invention in more detail. The rectifier comprises a choke 11 as well as a
changeover switch 10. The choke 11 is fitted between the first connection point
of the supplied load 14 and the output 16 of the changeover switch of the
rectifier of the intermediate circuit power. Two capacitors 17 in series are
connected in parallel with the changeover switch 10, and the second connection
point of the supplied load 14 is connected between the capacitors 18. A
controllable switch 24 is also fitted in series with the choke 11. By means of the
controllable switch the supplied load 14 can, if necessary, be isolated from the
rectifier 7 of the intermediate circuit power.
The rectifier 7 of the intermediate circuit power also comprises a measurement
26 of the current of the choke 11 as well as a measurement 27 of the voltage of
the supplied load 14. The rectifier 7 of the intermediate circuit power endeavors
to adjust the current of the choke 11 with the rectifier control 29. The magnitude
of the current is changed by switching the positive 36 or the negative 37
changeover contact of the changeover switch 10 in turns to the potential of the
positive 4 and the negative 5 busbar of the intermediate circuit of the frequency
converter. Pulse-width modulation (PWM modulation) is used for the control of
the switches. IGBT transistors are used as the changeover contacts. The
rectifier of the intermediate circuit power defines the power of the supplied load
14 by means of the measurements of the voltage 27 and the current 26 of the
supplied load.
Fig. 4 describes a rectifier 7 of the intermediate circuit power according to the
invention fitted to supply power from the intermediate circuit 4,5 of the
frequency converter to a phase of the electricity network 6. The neutral wire N
of the electricity network 6 is connected between the capacitors 18. A choke 11
is connected between the output 16 of the changeover switch and a phase of
the electricity network 6. A controllable switch 24 is also fitted in series with the
choke. The controllable switch closes after the intermediate circuit voltage has
risen to a pre-determined limit value, which is here 350 volts. By means of the
controllable switch 24 a possible surge current caused by sudden charging of
the capacitors 17 in connection with the closing of the main contactor of the
network is prevented.
The rectifier 7 of the intermediate circuit power is fitted to the intermediate
circuit of the frequency converter via the diodes 12,13. The diode 12 is fitted to
conduct current from the positive busbar 4 of the intermediate circuit of the
frequency converter to the collector of the positive changeover contact 36 of the
changeover switch 10 of the rectifier of the intermediate circuit power. The
diode 13 is fitted to conduct current from the emitter of the negative changeover
contact 37 of the changeover switch 10 of the rectifier 7 of the intermediate
circuit power to the negative busbar 5 of the intermediate circuit of the
frequency converter. The diodes connected in this way prevent the supply of
power from the electricity network 6 to the motor 2 via the rectifier 7 of the
intermediate circuit power, which is important from the standpoint of the safety
of the transport system, because in this case malfunctioning of the rectifier 7 of
the intermediate circuit power does not in a possible fault situation enable the
flow of power creating torque to the motor 2 from the electricity network 6.
Fig. 5 presents a rectifier control 29 of the rectifier of the intermediate circuit
power in more detail. The rectifier control 29 is fitted to control the rectifier 7 of
the intermediate circuit power in response to intermediate circuit voltage signal
25 of the frequency converter that indicates the power supply of the second
power source 2.
The intermediate circuit voltage 25 of the frequency converter 3 is measured
and compared by the comparator 40 to the first limit value 38 (U1) of
intermediate circuit voltage, which can be, for instance, 680 volts. After the
intermediate circuit voltage has increased to be greater than the first limit value
38, the comparator 40 gives permission to the rectifier control 29 to start to
control the power supplied to the load 14 from the intermediate circuit 4,5 of the
frequency converter with the rectifier 7 of the intermediate circuit power. In this
case the intermediate circuit voltage 25 starts to fall. The comparator 40
compares the intermediate circuit voltage to the second limit value 39 (U2) of
voltage, which can be, for instance, 650 volts. After the intermediate circuit
voltage has decreased to below the second limit value 39, the comparator
commands the rectifier control to stop the power supply of the rectifier 7 of the
intermediate circuit power.
The amplitude of the current reference of the choke 11, 20 is determined by
comparing the reference value 30 of the intermediate circuit voltage of the
frequency converter to the intermediate circuit voltage 25 measured with the
current regulator 31. The reference value of the intermediate circuit voltage can
be, for instance, 650 volts. The amplitude of the current reference grows in
proportion to the difference of the reference values and the actual values of the
intermediate circuit voltage. The current 26 measured by the choke tries to
adjust in the current regulator 33 according to the current reference 29 such that
the modulator 35 is controlled by means of the current regulator, by means of
which the switching reference of the changeover switch 10 is formed. A pulse
width modulator functions as the modulator, in which case the width of the
control pulse of the changeover switch is changed according to the output of the
current regulator,
In another embodiment the rectifier control 29 differs from the embodiment in
Fig. 5 such that the rectifier control does not contain a current regulator 31 at
all, but instead the amplitude of the current reference 29 is a constant. In this
case after the rectifier control has started the power supply from the
intermediate circuit 4,5 to the supplied load 14 with the rectifier 7 of the
intermediate circuit power, the current of the load is according to the current
reference 29 a constant in terms of its amplitude.
Fig. 6 presents an embodiment of the invention, in which three single-phase
rectifiers of the intermediate circuit power are fitted to the power control of the
transport system, for supplying power from the intermediate circuit 4,5 of the
power supply appliance 3 of the motor to a three-phase electricity network 6. In
this case each of the aforementioned single-phase rectifiers 7 of the
intermediate circuit power is connected to a different phase of the three-phase
electricity network 6. All three single-phase rectifiers 7 of the intermediate circuit
power are controlled with a common rectifier control 29. The rectifier control 29
determines the three-phase network current reference such that the currents
are phased with each other in accordance with the three-phase system. A
communication channel 41 is between the rectifier control and the single-phase
rectifiers 7 of the intermediate circuit power, via which the rectifier control sends
control commands to the single-phase rectifiers 7 of the intermediate circuit
power, for adjusting the network current according to the aforementioned three-
phase network current reference. The neutral wire N of the electricity network is
also connected to each single-phase rectifier of the intermediate circuit power,
in the same way as is described for one rectifier 7 in the embodiment of Fig. 4.
Fig. 7 presents an embodiment of the invention, in which a single-phase rectifier
7 of the intermediate circuit power is fitted to supply to the electricity network 6
the power generated by a solar panel 2 for the power supply circuit 3 of a
building. In this embodiment of the invention the power supply to the
electrification 42 of the building occurs from the electricity network 6 via the
inverter 3. The solar panel 2 is connected to the intermediate circuit 4,5 of the
inverter 3 via a separate DC/DC transformer 43 such that the voltage fitting
between the solar panel 2 and the DC intermediate circuit 4,5 of the inverter is
done with the aforementioned DC/DC transformer 43. The power supply to the
electrification 42 of the building can in this case occur wholly or partially from
the solar panel 2, in which case at least a part of the power of the electricity
supply of the building taken from the electricity network 6 can be replaced with
the power supply of the solar panel 2. When the power supply of the solar panel
exceeds the power requirement of the electrification 42 of the building, the
surplus power is supplied with the single-phase rectifier 7 of the intermediate
circuit power from the intermediate circuit 4,5 of the inverter to a phase of the
electricity network 6.
It is also possible that at least one accumulator is fitted in connection with the
solar panel 2, for the purpose of storing the energy produced by the solar panel.
The invention is not limited solely to the embodiments described above, but
instead many variations are possible within the scope of the inventive concept
defined by the claims below.
CLAIMS
1. A rectifier (7) of the intermediate circuit power, which contains interfaces
to the intermediate circuit (4, 5) of the power supply appliance (3) as well
as to the supplied load (14);
which power supply appliance (3) of the intermediate circuit contains
interfaces to a first power source (6) as weii as to a second power source
(2);
and which rectifier (7) of the intermediate circuit power contains a control
(29), in which is an input for the signal indicating the power supply of the
second power source;
and which control (29) is fitted to control the rectifier (7) of the
intermediate circuit power in response to the aforementioned signal
indicating the power supply of the second power source, for supplying to
the load (14) the power transmitted to the intermediate circuit from the
second power source (2);
characterized in that the rectifier (7) of the intermediate circuit power is
single-phase, comprising a choke (11) and also a changeover switch
(10), and in that the choke (11) is fitted between the first connection point
of the supplied load (14) and the output (16) of the changeover switch, at
least two capacitors (17) in series are connected in parallel with the
changeover switch, and in that the second connection point of the
supplied load (14) is connected between the capacitors (18).
2. Power control (1) of a transport system, which power control comprises
an electric motor (2) for moving the transport appliance as well as a
power supply appliance (3) of the motor, which comprises an
intermediate circuit (4,5) and which power supply appliance (3) of the
motor is fitted between the power source (6) and the electric motor (2),
characterized in that the power control (1) further comprises a single-
phase rectifier (7) of the intermediate circuit power, which single-phase
rectifier of the intermediate circuit power is fitted between the
intermediate circuit (4,5) of the power supply appliance of the motor and
the supplied load (14), for supplying power returning to the intermediate
circuit (4,5) from the electric motor (2) onwards to the load (14), and
which single-phase rectifier (7) of the intermediate circuit power
comprises a choke (11) and also a changeover switch (10); and in that
the choke (11) is fitted between the first connection point of the supplied
load (14) and the output (16) of the changeover switch of the rectifier of
the intermediate circuit power, at least two capacitors (17) in series are
connected in parallel with the changeover switch, and in that the second
connection point of the supplied load (14) is connected between the
capacitors (18).
3. Power control according to claim 1 or 2, characterized in that the
rectifier (7) of the intermediate circuit power can be controlled according
to the connected load (14).
4. Power control according to any of the preceding claims, characterized
in that the supplied load (14) comprises a power resistor.
5. Power control according to any of the preceding claims, characterized
in that the supplied load (14) comprises a power supply of the
electrification of a transport system.
6. Power control according to any of the preceding claims, characterized
in that the rectifier of the intermediate circuit power is fitted to supply
power from the intermediate circuit (4,5) of the power supply appliance of
the motor to a phase of the electricity network.
7. Power control according to any of the preceding claims, characterized
in that the positive (36) and negative (37) changeover contact of the
rectifier (7) of the intermediate circuit power can be controlled into a
conductive state simultaneously for the dynamic braking of the motor (2).
8. Power control according to any of the preceding claims, characterized
in that the (7) rectifier of the intermediate circuit power comprises a
definition of the power to be supplied to the load (14)
9. Power control according to any of the preceding claims, characterized
in that the rectifier (7) of the intermediate circuit power comprises a
measurement (26) of the current of the load, and in that the status of the
load is estimated on the basis of the measured current.
10.Method for controlling the power of a transport system, in which method:
a power supply appliance (3) of the motor is fitted between
the power source (6) and the electric motor (2)
a single-phase rectifier (7) of the intermediate circuit power
is;"fitted between the intermediate circuit (4,5) of the power
supply appliance of the motor and the supplied load (14)
characterized in that:
a changeover switch (10) is fitted in the single-phase rectifier
(7) of the intermediate circuit power,
a choke (11) is fitted between the output (16) of the
changeover switch (10) and the first connection point of the
supplied load (14)
at least two capacitors (17) in series are connected in
parallel with the aforementioned changeover switch (10)
a second connection point (18) of the supplied load (14) is
connected between the capacitors
11.Method according to claim 10, characterized in that:
the intermediate circuit voltage (25) is measured
the power supply from the intermediate circuit (4,5) to the
supplied load (14) is started with the single-phase rectifier
(7) of the intermediate circuit power after the intermediate
circuit voltage has exceeded the limit value (38) of voltage.
the power supply from the intermediate circuit (4,5) to the
supplied load (14) is stopped after the intermediate circuit
voltage has fallen below the limit value (39) of voltage.

The power control of a transport system comprises an electric motor (2) for moving the transport appliance as well
as a power supply appliance (3) of the motor, which comprises an intermediate circuit (4,5). The power supply appliance of the
motor is fitted between the power source (6) and the electric motor (2). The transport system further comprises a rectifier (7) of the
intermediate circuit power, which is fitted between the intermediate circuit (4.5) of the power supply appliance of the motor and the
supplied load (14) for transmitting intermediate circuit power to the supplied load.