The present invention relates to an elevator comprising an elevator motor, a motor drive for the
elevator motor having a frequency converter comprising a rectifier bridge, an inverter bridge and a
DC link in between, which frequency converter is controlled via a controller, the rectifier bridge being
connected to mains via three feed lines comprising chokes, whereby the rectifier bridge is being
realised via controllable semiconductor switches so that it is able to refeed electricity into mains
during generator mode of the elevator or elevator group. Further, the elevator has an isolation relay
being located between the feed lines and mains as well as a backup power supply at least for
emergency drive operation. To effect an emergency drive, the elevator comprises an emergency
control for performing an automatic emergency drive, which emergency control might be a separate
component but is preferably integrated with the controller. For feeding power to the DC link the
backup power supply is via a first switch connectable with only a first of said feed lines and the
necessary Dc link voltage is provided via a boost activity of at least one of the semiconductor
switches of the rectifier bridge connected with the first feed line and the at least one choke provided
in the firstfeed line.
The controller regularly also controls the elevator brakes of the elevator to release them in normal
operation as well as during an emergency drive. The backup power supply which is regularly realized
via a battery may also be formed by other power supplies as e.g, supercapacitors. This technology
forms the background of the invention. Such kind of elevator is disclosed in the WO 2008/100259 A1.
It is object of the present invention to provide an elevator which facilitates and allows an automatic
emergency drive to release trapped passengers.
The object is solved with an elevator according to claim 1. The object is further solved with a method
according to claim 17, Preferred embodiments of the invention are subject matter of the correlated
dependent claims. Preferred embodiments of the invention are also described in the specification
and drawings,
According to the invention, the second and/or third of said feed lines is via a second switch
connectable to a power supply of an elevator car door, whereby the first switch connecting the
backup power supply to the firstfeed line as well as the second switch connecting the power supply
of the elevator car door are controlled by the emergency control.

This inventive solution enables the use of the rectifier bridge on one hand to act as a booster in
connection with a choke in the first feed line to transform the DC voltage of the backup power
supply, hereinafter battery, to the required DC link voltage and the second and third feed line are
simultaneously used to provide alternating current as power supply for the elevator car door which
power supply is connected via the second switch to the second and/or third feed line. Thus, the
emergency control which is usually integrated in the controller is able to release the elevator brakes
and to start rotating the elevator motor to move the elevator car to the adjacent landing of the
elevator. When the elevator car has arrived at the landing, the emergency control is via the second
and/or third feed line able to supply the necessary power for the elevator car door to open it so that
the trapped passengers can be released. The emergency control may feed power for the elevator car
door also during emergency drive, to provide closing torque to keep the doors closed. The rectifier
bridge which is a modulated rectifier bridge comprising of semiconductor switches controlled by the
controller is therefore able to simultaneously fulfil the task of increasing (boosting) the DC voltage for
the DC link as well as to provide the AC voltage for the elevator car door.
The elevator comprises the automatic emergency drive function which is automatically performed by
the emergency control in case of a power failure of (public) AC mains.
According to the invention, the elevator comprises a first feedback circuit configured to provide to
the emergency control a first information indicating the switching state of the isolation relay and a
second feedback circuit configured to provide to the emergency control a second information
indicating the'SWitching state of the first switch. The emergency control is configured to selectively
allow or prevent the emergency run on the basis of the first information and the second information.
With this measure it is possible to replace traditional safety relays or -isolation relays with normal
isolation means, i.e. one or more isolation relays. These normal isolation means are not as reliable
but simpler and cheaper than traditional safety relays. The lower reliability of the normal isolation
means can be compensated with improved supervision by means of the emergency control /
feedback circuits. For example, the emergency control may allow closing of the first switch only after
it has detected opening of the isolation relay. Consequently, emergency control may allow closing of
the isolation relay only after it has detected opening of the first switch. Emergency run may be
allowed only after detecting a correct sequence of opening of the isolation relay and closing of the
first switch.

In particular, the isolation relay may comprise an auxiliary contact and the first feedback circuit may
be configured to provide to the emergency control as the first information an indication of switching
state of the auxiliary contact. The second feedback circuit may be connected to the first feed line
between the isolation relay and the first switch to provide to the emergency control as the second
information an indication of presence or absence of line voltage in said first feed line between the
isolation relay and the first switch. The second information thus indicates when line voltage is
present or absent, i.e. is it possible to close the first switch. After closing the first switch, the second
information indicates presence of backup power supply voltage, i.e. has the first switch closed
properly. When this is the case, emergency run may be started.
Of course, the second feedback circuit could be connected with a switching status indicator of the
first switch, e.g. an additional relay contact of the switch changing its signal status with the switching
status. However, in a preferred embodiment of the invention the second feedback circuit is
connected to the first feed line and is configured to provide to the emergency control information
regarding the presence or absence of line voltage in said first feed line. Now the emergency control is
configured to derive from the line voltage in the feed line information about the switching status of
the first switch. This is a very easy way to get information about the switching status of the first
switch without needing a switching status indicator of the first switch.
In a preferred embodiment of the invention the first feedback circuit comprises an auxiliary contact
of the isolation relay connected to a signal line and is configured to provide to the controller or
emergency control an indication of switching state of the isolation relay as the first information.
This is an easy way to provide and forward the first information to the emergency control.
Preferably the emergency control is integrated with the controller so that it already shares with the
controller all essential input and output lines necessary for the control of an emergency situation.
This further provides a space saving solution and minimises the number of necessary components.
In a preferred embodiment of the invention, the backup power supply is connected to the DC link via
a DC/DC converter, preferably in flyback topology. Via this measure, the capacitor of the DC link can
be charged up to a sufficient voltage level before connecting the first feed line to the backup power
supply to perform the boost action for the DC link. The advantage of the DC/DC converter is that the
current provided by the DC/DC converter to the DC capacitor is limited so that the charge current
peak which is present at the start of the charge up of the capacitor does not harm the DC/DC
converter, the battery or the first switch. Furthermore, by the fact that now the DC link is charged up

by the DC/DC converter and the battery to a certain level, the current is limited when the
semiconductors of the rectifier bridge connected to the first feed line begin the boosting of the
battery voltage to the DC link voltage. If this action would start with an unloaded capacitor, the high
initial current might harm the corresponding semiconductors of the rectifier bridge.
In a preferred embodiment, the DC/DC converter is bidirectional and is configured on one hand to
generate a DC voltage for the DC link which is higher than the battery voltage, and on the other hand
the DC/DC converter is configured to form a charging circuit for the battery fed from the DC link.
Thus, the DC/DC converter has two functions, i.e. to pre-charge the capacitor in case of mains power
off so as to enable the above-mentioned emergency drive action and on the other hand to charge
the battery during normal operation of the elevator. Via this measure, it is also ensured that the
battery capacity is high enough in any case of mains power off,
Preferably, the manual drive circuit is disposed in a remote control unit outside of elevator shaft, so
that the person performing the manual rescue drive does not need to enter the elevator shaft.
In a preferred embodiment of the invention a transformer is arranged between the car door
arrangement (door operator) and the second switch, so that the supply voltage can be easily adapted
to the requirements of the door arrangement..
In an alternative embodiment, the DC/DC converter is one directional such that is it configured only
to charge the battery from the DC link. This means that the DC/DC controller only has one MOSFET
transistor in the DC link side of the transformer, and the other MOSFET transistor in the battery side
is not needed.
Preferably, the DC/DC converter comprises at least one PWM controller, preferably two PWM
controllers, namely one on each side, which is/are controlled via the controller. The programs to
control the PWM controllers are then preferably stored in the controller so that it is optimized for
battery charging during normal operation as well as for pre-charging the capacitor in the DC link
during emergency drive.
In this connection it is to be mentioned that preferably a capacitor is provided in the DC link which is
the normal frequency converter topology to minimize voltage ripple in the DC link.

In a preferred embodiment of the invention, the controller comprises an auxiliary power input being
connectable to the backup power supply. The DC link usually supplies power to the controller.
Anyway, during periods of non-use, e.g. during nights as well as in any case of mains power off, the
voltage of the DC link might drop so that is not any longer sufficientto form a power supply for the
controller, at least to perform the emergency drive. In this case, this auxiliary power input is
advantageous as it can be connected to the backup power supply during mains power off to ensure
that all necessary operations in connection with an emergency drive, independent whether it is an
automatic emergency drive or a manual emergency drive, can be performed.
Preferably, a second DC/DC converter is connected with the auxiliary power input. This has the
advantage that the second DC/DC converter can boost or reduce the incoming voltage to the voltage
level which is adapted as supply voltage for the controller. In this connection it is advantageous if the
second DC/DC converter is a PWM-controlled which enables a wide input voltage range. In this case
it is preferable that the PWM of the second DC/DC converter has its own separated control as the
function of the controller is not ensured in case of mains power off because of missing supply
voltage.
In a preferred embodiment of the invention, the DC/DC converter of the battery is connected to the
auxiliary power input, preferably to the second DC/DC converter, preferably via a diode. In this case,
the controller may receive the energy from the DC/DC converter in a mains power off situation when
the DC/DC converter is starting to charge up the capacitor in the DC link which provides a DC voltage
which is higher than that needed by the controller so that the voltage level can be adapted to the
correct voltage for the controller by the second DC/DC converter. By providing the diode between
the DC/DC converter and the second DC/DC converter, it can be ensured that the voltage is only
flowing in the direction from the DC/DC converter to the second DC/DC converter and thus to the
auxiliary power input of the controller. So the second DC/DC converter receives power from output
of the DC/DC converter when it has higher voltage than the battery, otherwise second DC/DC
converter receives power from the battery via the third switch whereby the first and second diodes
act as selector or the highest input voltage for the second DC/DC converter.
Preferably, an activation circuit is provided between the backup power supply and the auxiliary
power input, in which activation circuit a third switch is provided which is controlled via the
emergency control (controller) as well as via the manual drive arrangement. Via this measure, power
supply from the battery directly to the auxiliary power input - or to the second DC/DC converter
connected to it - happens via this activation circuit, If the controller has still enough power, the

emergency control closes the third switch which is preferably a semiconductor switch and thus it is
ensured that the battery is connected with the auxiliary power input of the controller, possibly via
the second DC/DC converter to ensure a correct voltage level. Thus, in any case of mains power off, a
reliable function of the controller and the emergency control is ensured via this activation circuit and
the controller can keep awareness of current elevator status.
Preferably, the third switch is connected to the second DC/DC converter via a diode, which ensures
that power only flows one way to the auxiliary power input of the controller. As preferably also the
first DC/DC converter is connected to the auxiliary power input - or second DC/DC converter - via a
diode the power is fed to the auxiliary power input either from the DC/DC converter or from the
activation circuit, i.e. which source provides the higher supply voltage level.
Preferably the second DC/DC converter is PWM-controlled enabling a wide input voltage range.
Preferably, at least one capacitor is connected between the positive and negative branch of the DC
link. This capacitor smoothes the ripple in the DC voltage of the DC link. Preferably this capacitor may
be formed by a series connection of two capacitors in which case the connection point of the two
capacitors can be used as a neutral point of the DC link.
Preferably, the third switch in the activation circuit is controlled via at least one semiconductor
switch controlled by the emergency control as well as by the manual drive arrangement. That means
the emergency control during its automatic emergency drive function controls the.third switch to
close so that power is fed from the battery to the auxiliary power input of the emergency control
(controller).
Preferably, at least one capacitor is connected between the positive and negative branch of the DC
link which enables a smooth DC link voltage preferably when the DC link voltage is boosted via the
connection of the backup power supply to the first feed line in connection with its choke and the
corresponding semiconductor switches of the rectifier bridge.
It is further to be mentioned that the semiconductor switches of the rectifier bridge connected to the
first feed lines are operated during boost operation preferably with a frequency of 100 Hz -10 kHz to
provide in connection with the choke located in the first feed line the sufficient DC voltage for the DC
link. Hereby, the semiconductor switch of the lower half-bridge controls via its switching cycle the
voltage, which is based on the inductance voltage peaks of the choke(s), which voltage peaks run via

the anti-parallel diode of the upper semiconductor switch to the positive branch of the DC link. Of
course via this measure a voltage is boosted which is much higher than the feed voltage of the
backup power supply.
Preferably, the semiconductor switches of the rectifier bridge are provided with anti parallel diodes,
so that easier voltage boosting function in the above sense is enabled.
The invention also refers to a method for performing a rescue operation in an elevator according to
the type which is described above. This method works as follows: In case of mains power off, the
isolation relays are opened so that the feed lines are no longer connected with AC mains. Then, the
backup power supply is initiated to feed direct current to the DC link via the DC/DC converter which
boosts the DC voltage to a level which is adapted for the DC link (regularly several hundred volts)
from the battery voltage level (regularly 20 to 63 V). This pre-charges the capacitor in the DC link.
The emergency control (controller) then energizes an activation circuit via the emergency control
,which activation circuit connects the backup power supply to an auxiliary power input of the
emergency control to perform an automatic emergency drive. The backup power supply is connected
to the first feed line and the lower semiconductor of the rectifier bridge connected to the first feed
line is controlled to switch, e.g. with a frequency between 100 Hz and 100 kHz which is optimal for
voltage boosting. In the automatic rescue drive, the emergency control energizes the elevator brakes
to release by controlling power supply from the DC link to the brakes and begins rotating the
elevator motor via control of the inverter bridge.
Via the semiconductor switches connected to the second and/or third feed line an AC voltage is
created in the second and/or third feed line which is/are connected as power supply to the door
arrangement of the elevator car.
After the elevator car has reached a landing zone the car doors are opened to release the passengers
with the supply voltage fed via the second and/or third feed line.
Via the semiconductor switches of the rectifier bridge connected to the second and third feed line,
an AC voltage is created in these feed lines, and the second and/or third feed line is connected via a
second switch to the door arrangement, i.e. door drive and door controller of the elevator car as a
power supply, If only one of the second or third feed line is connected as a power supply to the car
arrangement the other pole for the power supply has to be created by a neutral voltage level of the

DC link. This neutral point could be created for example by using the connection point between two
capacitors which are connected in series between the two branches of the DC link. Thus either the
power supply is between the second or third feed line on one hand and the neutral point on the
other hand or between the second and third feed line. After the elevator car has reached a landing
zone, the car doors are then opened via the connection of the second and/or third feed line to the
door drive of the elevator car. Thus, an automatic drive for releasing trapped passengers is possible
in an economical way.
Preferably, a transformer is arranged between the car door arrangement and the second switch such
that the AC voltage created in the second and third feed lines is supplied to the transformer and
transformed to an adapted voltage for the door arrangement.
Preferably, the DC/DC converter which is used to pre-charge the capacitor in the DC link before
connecting the backup power supply to the first feed line is used in a normal elevator operation as a
charging circuit for the backup power supply. Thus, the different functions can be realized with a
minimum of hardware components.
It shall be clear that the controller may be a separate or integrated part of the elevator control, and it
may comprise or being connected with the control of the elevator brakes to release the elevator
brakes during an emergency drive. Hereinafter, the control of the elevator brakes is described to be
integrated with the controller, but it is clear that it may be a separate control component connected
to the elevator control and/or controller. The controller is usually a digital signal processor which is
connected by control lines with the semiconductors of the rectifier bridge as well as of the inverter
bridge and it has inputs for obtaining status data of the elevator motor as velocity and electric values
of the inverter bridge and of the elevator motor.
Above, the power supply to the emergency control (controller) in case of mains power off has been
realized via its auxiliary power input. Of course, the auxiliary input is preferable but not really
necessary to perform the above functions. In this case the power is fed from the DC/CD converter or
activation circuit to the (normal) power input of the emergency control (controller).
The semiconductor switches of the rectifier bridge and/or inverter bridge may preferably be IGBTs or
MOSFETs or SiC MOSFETs.

It shall be clear for the skilled person that the above-mentioned embodiments may be combined
with each other arbitrarily.
Following terms are used as synonyms: backup power supply - battery; rectifier bridge - modulated
rectifier bridge; DC/DC converter-first DC/DC converter; capacitor- smoothing capacitor; elevator
brake - motor brake; landing zone indicator - door zone indicator; fourth switch - opto coupler;
controller- controller including emergency control -emergency control;
The invention is hereinafter described via a preferred embodiment in connection with the drawings.
Fig. 1 shows an electric diagram of the motor and brake drive section of an elevator including
automatic emergency drive components, and
Fig. 2 shows an electric diagram similar to Fig. 1 with a simplified charging arrangement for the
backup power supply.
Fig. 1 shows an elevator 10 comprising an elevator motor 12 which is controlled by an elevator drive
14 which is embodied as a frequency converter comprising a modulated rectifier bridge 16 consisting
of semiconductor switches with antiparallel diodes, an inverter bridge 18 and a DC link 20 in
between. The DC link 20 comprises a smoothing capacitor 22. The elevator motor 12 comprises
preferably a traction sheave 24 over which a hoisting rope 26 is running carrying an elevator car 28
and optionally a counterweight 30. Alternatively, the hoisting rope 26 may be connected with the
underside of the car to build a closed loop (with or without counterweight 30). Further, the elevator
motor 12 comprises two parallel elevator brakes 32a, 32b, Finally, a controller 34 is provided which
additionally forms an emergency control of the elevator drive 14. The controller 34 controls the
semiconductor switches 17 of the rectifier bridge 16, the semiconductor switches of the inverter 18,
the elevator brakes 32a, 32b and it is connected with a landing zone indicator 36 showing whether or
not the elevator car has arrived a landing zone of the elevator 10. Preferably the controller gets input
of the electrical values of the inverter bridge and elevator motor and eventually a tachometer signal
of an encoder at the motor shaft or traction sheave.
The rectifier bridge 16 is connected via three feed lines 38a-c to an isolation relay 40. The three feed
lines 38 a-c are connected via the isolation relay 40 with AC mains 42, i.e. with normally a three-
phase AC public network. In each feed line 38a-38c, two chokes 44a, 44b are located, The isolation
relay 40 comprises an auxiliary contact 40' connected to a signal line 43, The auxiliary contact 40' and
the signal line 43 form a first feedback circuit 41 to provide an indication of the switching state of the

isolation relay 40 to the emergency control 34 as first information. Between the feed lines 38a-38c, a
capacitor bridge 46 is connected which in connection with the chokes 44a and 44b act as an AC line
filter. The elevator drive 14 comprises a backup power supply 48 preferably in form of a battery
which is connected to a DC/DC converter 50, preferably in a flyback topology. The DC/DC converter
50 comprises on both sides a PWM controller which is controlled by the controller 34. The battery 48
is connected via a first switch 52 to the first feed line 38a. A second feedback circuit 47 is provided
between the first switch 52 and the controller (emergency control) 34 which second feedback circuit
47 is configured to provide to the emergency control 34 second information indicating switching
state of the first switch 52, This second feedback circuit 47 may receive the switching status via a
relay contact of the first switch 52. Alternatively or additionally the second feedback circuit 47 may
be connected to the first feed line 38a, e.g. via a resistor 45, When the isolation relay 40 opens ,
normally there is no voltage on the feed line any longer. However, when the first switch 52 closes the
feed line is provided with voltage from the battery 48. Thus , by detecting the voltage in the first
feed line it is possible to derive the switching status of the first switch 52.
The first switch 52 also disconnects the capacitor bridge 46 from the first feed line 38a
simultaneously with connection to the battery 48. The second and third feed line are connected with
second switches 54a, 54b with door arrangement 56 comprising a door controller as well as a door
drive and the car door.
The controller 34 has preferably an auxiliary power input 58 connected preferably to a second DC/DC
converter 60. The second DC/DC converter 60 acts as a kind of voltage regulator for the auxiliary
power input 58 of the controller 34.
While the first branch of the DC/DC converter 50 is connected with the battery 48, the second branch
is connected to the DC link 20. Furthermore, additionally the second branch of the DC/DC converter
50 is connected via a first diode 62 to the second DC/DC converter 60 at the auxiliary power input 58
of the controller 34. The battery 48 is via an activation circuit 64 directly connected to the second
DC/DC converter 60, and thus to the auxiliary power input 58 of the controller 34. The activation
circuit 64 comprises a third switch 66 and a second diode 68. So the second DC/DC converter 60
receives power from output of the DC/DC 50 converter when it has higher voltage than the battery
48, otherwise second DC/DC converter 60 receives power from the battery 48 via the third switch 66
whereby the first and second diodes 62 and 68 act as selector or the highest input voltage for the
second DC/DC converter 60.

In this activation circuit 64 the third switch 66 is preferably a semiconductor switch which is activated
via a boost transistor 72 connected to the gate of the third switch 66. The boost transistor 72 is
controlled either via a transistor 70 (or other semiconductor switch) which is controlled via the
controller 34. The function of the elevator 10 in an emergency case is carried out hereinafter:
In case of a power off of the mains 42, the isolation relay 40 is opened. Now, there are two cases.
The first case is that the voltage level in the DC link 20 is sufficiently high enough for the controller 34
to operate. In this case, the transistor 70 controlled by the controller 34, i.e. the emergency control
thereof, is activated which closes the third switch 66 in the activation circuit 64 so that the battery 48
is via the second DC/DC converter 60 connected to the auxiliary power input 58 of the controller 34.
This power supply via the activation circuit 64 to the auxiliary power input 58 enables the controller
34 to operate properly. Now the controller 34 controls the two PWM controllers of the DC/DC
converter 50 to charge up the smoothing capacitor 22 in the DC link 20.
As it has been mentioned above, the first feedback circuit 41 is connected between the isolation
relay 40 and the controller 34 to indicate isolation relay 40 status to the controller 34. This feedback
circuit 41 may comprise an auxiliary contact 40', which is connected to a signal line 43 of the
feedback circuit 41 that leads to the input of the controller 34. The auxiliary contact 40' selectively
interrupts or connects a detection signal to the input of the controller 34 such that status of the
auxiliary switch40' / isolation relay 40 can be determined therein.
A second feedback circuit 47 is connected between the first switch 52 and the controller 34 to
indicate first switch 52 status to the controller 34. The first switch 52 may be provided with an
auxiliary contact, which is connected to a signal line that leads to input of the controller 34. The
auxiliary contact selectively interrupts or connects a detection signal to the input of the controller 34
such that status of the auxiliary switch / isolation relay 40 can be determined therein.
The second feedback circuit 47 is connected between the first switch 52 and the emergency control
34 to additionally indicate the status of the first switch (52) to the emergency control (34). The
emergency control 34 is configured to selectively allow or prevent an emergency run on the basis of
the status of the isolation relay 40 and the status of the first switch 52.
After the voltage in the DC link 20 has reached a sufficient level, the first switch 52 is closed by the
controller 34 so that the battery 48 is connected to the first feed line 38a. Simultaneously, the
capacitor bridge 46 is separated from the first feed line 38a. Now, a DC voltage is connected to the

first feed line 38a and the lower semiconductor 17f of the rectifier bridge 16 is controlled to open
and close in a frequency of about 100 Hz to 10 kHz. This leads to corresponding voltage peaks of the
chokes 44a and 44b in the first feed line 38a which voltage flows via the antiparallel diode of the
upper semiconductor 17c to the DC link 20 and charges it to a desired voltage level. Via the fact that
the smoothing capacitor 22 in the DC link has been pre-charged bythe DC/DC converter 50, the
current flowing through the antiparallel diode 17c is not too high for it to be harmed. Now, also the
DC link 20 has a sufficient voltage level so that the second switches 54a, 54b can be closed to
energize the door arrangement 56 to ensure that the car doors are closed during emergency drive.
The controller 34 now controls the elevator brakes 32a and 32b to release and controls the
semiconductors in the inverter bridge 18 to rotate the elevator motor 12. When the elevator car 28
has reached the level of a door zone, this is signalized to the controller 34 via landing zone indicator
36. Then the controller 34 stops rotating the elevator motor 12 and de-energizes the elevator brakes
32a, 32b enabling them to grip and keep the traction sheave 24 stopped. Now, the controller 34
initiates the door controllers and door drives of the door arrangement 56 to open the car door which
is possible via the power supply via the second and third feed lines 38b and-38c which are connected
to the door drive and door controller via second switch 54a, 54b.As normally the car doors
connectors are coupled to the corresponding landing doors both are opened and the trapped
passengers can be released.
If in a second situation the voltage level in the DC link at the beginning of the emergency drive is not
sufficiently high for the controller 34 to work, the controller 34 is not able to activate the transistor
70 to close the third switch 66 in the activation circuit 64. In this case, a maintenance person or an
operator has to push a manual drive switch 82 in the manual drive circuit 78 which closes the fourth
switch 74 parallel to the transistor 70 and thus closes via boost transistor 72 the third switch 66
connecting the battery 48 to the second DC/DC converter 60 at the auxiliary power input 58 of the
controller 34 via the second diode 68. Now, the controller 34 is able to work and to start the
necessary steps for performing the manual emergency drive as mentioned above with starting pre-
charging the capacitor 22 in the DC link 20 via the DC/DC converter 50. Usually the manual drive
switch has to be kept pushed until the car has arrived at a landing and the doors are opened so that
the trapped persons may be released.
The automatic emergency drive maybe started automatically or controlled via a remote maintenance
centre, which is connected to the controller 34 (and/or the elevator control) via a public
communication network.

An alternative embodiment shown in Fig. 2 is almost identical to Fig. 1 with the difference that the
DC/DC converter 51 is only one directional such that is it configured only to charge the battery 48
from the DC link, but in contrast to Fig. 1 it is not able to feed boosted DC voltage to the DC link 20.
In this case the DC/DC controller 51 only has one PWM controlled MOSFET transistor in the DC link
side of the transformer, and the other MOSFET transistor in the battery side is not needed.
In this alternative embodiment, the initial charging of DC link takes place via a pre-charge line S3 in
which a current limiting resistor 84 and a third diode 86 is connected. This pre-charge line is
connected between the output of the third switch 64 and the positive branch DC+ of the DC link 20..
This embodiment has the advantage of lower cost. Of course in this case the capacitor 22 can only be
charged to the voltage level of the battery 48.
The capacitor 22 in the DC link 20 can also be formed by a series connection of two capacitors in
which case the connection point of the two capacitors is used as a neutral point of the DC link, e.g.
for connecting the door arrangement 56 between only one of the second or third feed line 38b, 38c
and this neutral point.
The above elevator therefore allows automatic as well as manual emergency drive operation with a
minimum of hardware components and with a high level of security and reliability.
The invention is not restricted to the disclosed embodiments but may be varied within the scope of
the claims as attached,

List of reference numbers
10 elevator
12 ' elevator motor
14 elevator drive
16 rectifier bridge
18 inverter bridge
20 DClink(DC+, DC-)
22 smoothing capacitor
24 traction sheave
26 hoisting rope - a set of hoisting ropes
28 elevator car
30 counterweight
32a,b elevator brakes - motor brakes
34 controller (including emergency control, e.g. being part of the elevator control)
36 landing zone indicator-door zone indicator
38a,b,c three feed lines to the rectifier bridge
40 main isolation relay
40' auxiliary contact
41 first feedback circuit
42 AC mains (public AC network)
43 signal line of the first feedback circuit
44a first chokes in the feed lines
44b second chokes in the feed lines
45 resistor between first feed line and second feedback circuit
46 capacitor bridge
47 second feedback circuit
48 " backup power supply - battery
50 (first) DC/DC converter
52 first switch (relay)
54a,b second switch
56 door arrangement (door drive with door controller and car door)
58 auxiliary power input of the controller

60 second DC/DC converter at auxiliary power input
62 first diode between DC/DC converter and second DC/DC converter
64 activation circuit
66 third switch
68 second diode
70 transistor controlled by the controller
72 boost transistor for third switch
74 fourth switch - opto coupler
76 manual drive arrangement
78 manual drive circuit
80 second backup power supply - second battery in the manual drive circuit
82 pre-charge line
83 pre-charge line
84 resistor
86 third diode

Claims
1. Elevator comprising
- an elevator motor (12)
- a motor drive (14) for the elevator motor (12) having a frequency converter comprising a rectifier
bridge (16), an inverter bridge (18) and a DC link (20) in between, which frequency converter is
controlled via a controller (34), the rectifier bridge (16) being connected to AC mains (42) via three
feed lines (38a-c) comprising chokes (44a,b), and the rectifier bridge (16) being realised via
controllable semiconductor switches (17a-f),
- an isolation relay (40) being located., between the/feed lines (38a-c) and AC mains (42),.
- a backup power supply (48) at least for emergency drive operation,
- an emergency control (34) for performing an automatic emergency drive,
- the backup power supply (48) is via a first switch (52) connectable with only a first (38a) of said feed
lines (38a-c),
characterized in that
- a second and/orthird (38b,c) of said feed lines (38a-c) is via a second switch (54a,b) connectable as
power supply to a car door arrangement (56), while the second and third feed lines (38b,c) are
separated from AC mains (42) with the isolation relay (40), and
- the first switch (52) as well as the second switch (54a,b) are controlled by the emergency control
(34),
and in that the elevator comprises:
- a first feedback circuit (41) configured to provide to the emergency control (34) first information
indicating the switching state of the isolation relay (40),
- a second feedback circuit (47) which is configured to provide to the emergency control (34) second
information indicating switching state of the first switch (52),
'and in that the emergency control (34) is configured to selectively allow or prevent the emergency
drive operation on the basis of the first information and the second information.
2. Elevator according to claim 1, wherein the second feedback circuit (45) is connected to the first
feed line (38a), which second feedback circuit (45) is configured to provide to the emergency control
(34) information regarding the presence or absence of line voltage in said first feed line (38a), and
that the emergency control is configured to derive from the line voltage in the feed line (38a)
information about the switching status of the first switch (52).

3. Elevator according to claim 1 or 2, wherein the first feedback circuit (41) comprises an auxiliary
contact (40') of the isolation relay (40) connected to a signal line (43) and is configured to provide to
the emergency control (34) an indication of the switching state of the isolation relay (40) as the first
information.
4. Elevator according to one of the preceding claims, wherein the backup power supply (48) is
connected to the DC link (20) via a DC/DC converter (50), preferably in flyback topology.
5. Elevator according to claim 4, wherein the DC/DC converter (50) is bidirectional and is configured
to generate a DC voltage for the DC link (20) which is higher than the backup power supply voltage
(48), and which DC/DC converter (50) is further configured to be a charging circuit for the backup
power supply (48) fed from the DC link (20).
6. Elevator according to claim 4, wherein the DC/DC converter (51) is one directional and a pre-
charging line (82) is connected between the backup power supply (48) .and the positive busbar (DC+)
of the DC link (20), preferably via a third switch (66) of an activation circuit (64).
7. Elevator according to one claims 4 to 6, wherein the DC/DC converter (50) comprises at least one
PWM controller which is/are controlled via the controller (34).

8. Elevator according to one of the preceding claims, wherein the controller (34) comprises an
auxiliary power input (58) being connectable to the backup power supply (48).
9. Elevator according to claim 8, wherein a second DC/DC converter (60) is located in the auxiliary
power input (58).

10. Elevator according one of claims 4 to 7 and one of claims 8 to 9, wherein the DC/DC converter
(50) is connected to the auxiliary power input (58), preferably to the second DC/DC converter (60),
preferably via a first diode (62).
11. Elevator according to one of claims 8 to 10, wherein an activation circuit (64) is provided between
the backup power supply (48) and the auxiliary power input (58), in which activation circuit (64) a
third switch (66) is provided which is controlled via the emergency control (34) and via the manual
drive circuit (76).

12. Elevator according to one of claims 8 to 10 and claim 11, wherein the third switch (66) is
connected to the second DC/DC converter (60) via a second diode (68).
13. Elevator according to claim 11 or 12, wherein the third switch (66) is controlled via at least one
transistor (70) controlled by the emergency control (34).
14. Elevator according to claim 13, wherein parallel to the transistor (70) a fourth switch (74) of a
manual drive circuit (78) is connected, which is preferably an opto-coupler.
15. Elevator according to claim 14, wherein the manual drive circuit (78) comprises a second backup
power supply (80) and a manual drive switch (82), which manual drive circuit (78) controls the third
switch (66) via the opto-coupler (74).
16. Elevator according to one of the preceding claims, wherein the backup power supply (48} is or
comprises a battery.
17. Method for performing a rescue operation in an elevator according to one of the preceding
claims, characterized by following steps:

- in case of mains power off the isolation relay (40) is opened and the backup power supply (48) is
initiated to feed direct current to the DC link (20) via a DC/DC converter (50),
- an activation circuit (64) is energized via the emergency control (34), which activation circuit (64)
connects the backup power supply (48) with an auxiliary power input (58) of the emergency control
(34) to selectively perform an automatic emergency drive,
- the backup power supply (48) is connected to the first feed line (38a) and the lower semiconductor
(17f) of the rectifier bridge (16) connected to the first feed line (38a) is controlled to switch with a
frequency between 100 Hz and 100 kHz,
- whereby in the automatic emergency drive, the emergency control (34) energizes the elevator
brakes (32a,b) to release by controlling power supply from the DC link (20) to the brakes (32a,b) and
beginsJ"otating the elevator motor (12) via control of the inverter bridge (18), and
- wherein via the semiconductor switches (17a,b,d,e) connected to the second and third feed line
(38b,c) an AC voltage is created in the second and/or third feed line (38b,c) which is/are connected
as power supply (48) to the door arrangement (56) of the elevator car (28),
- after the elevator car (28) has reached a landing zone the car doors are opened to release the
passengers with the supply voltage fed via the second and/or third feed line (38b,c),

18. Method for operating an elevator according to one of claims 1 to 16 and designed to use the
method for performing a rescue operation according to claim 17, wherein the DC/DC converter (50)
is used in normal elevator operation to charge the backup power supply (48).