DE102022002713A1 - System for contactless power transmission from a primary conductor to a handset - Google Patents

Abstract

System for non-contact energy transmission from a primary conductor to a mobile part, the mobile part having a secondary winding, a capacitance being connected in series or in parallel to form a resonant circuit of the secondary winding, a rectifier being supplied from the resonant circuit, with a smoothing capacitor being arranged at its output to which a load, in particular a consumer, is connected in parallel, with the rectifier having controllable switches with which the resonant circuit and/or the input of the rectifier can be short-circuited, in particular with the resonant circuit feeding the AC voltage-side connection of the rectifier and the smoothing capacitor being connected to the DC voltage-side connection and/or the load is fed from the connection on the DC voltage side.

Description

The invention relates to a system for contactless power transmission from a primary conductor to a handset.

From the EP 2 740 208 B1 a secondary-side rectification is known in a system that transmits energy without contact.

The invention is therefore based on the object of further developing a system for contactless energy transmission in a compact manner.

According to the invention, the object is achieved with the system according to the features specified in claim 1.

Important features of the invention in the system are that the system is provided for contactless energy transmission from a primary conductor to a handset,
wherein the handset has a secondary winding,
a capacitance being connected in series or in parallel to form a resonant circuit of the secondary winding,
A rectifier is supplied from the resonant circuit, at the output of which a smoothing capacitor is arranged, to which a load, in particular a consumer, is connected in parallel,
wherein the rectifier has controllable switches with which the resonant circuit and/or the input of the rectifier can be short-circuited,
In particular, the resonant circuit feeds the connection of the rectifier on the AC voltage side and the smoothing capacitor on the connection on the DC voltage side
is connected and/or the load is fed from the DC-side connection.

The advantage here is that the rectifier can also be used as a regulator and the system can therefore be designed to be very compact.

In an advantageous embodiment, the handset can be moved on a floor and the secondary winding is arranged on a side of the handset facing the floor.
in particular where the primary conductor is laid in the ground in an elongated manner or is arranged in the ground as a coil winding. The advantage here is that the handset does not require a large energy storage device since it can be charged while driving. Thus, the handset is compact executable.

In an alternative advantageous embodiment, the mobile part is a rail vehicle, with the primary conductor being movable along or parallel to a rail that the mobile part can travel on. The advantage here is that the handset can be designed as a compact rail vehicle, since the energy store can be selected to be small and the handset can therefore be designed to be compact.

In an advantageous embodiment, the resonant frequency of the resonant circuit formed from the secondary winding and the capacitance, in particular the oscillating circuit, is equal to the frequency of the alternating current impressed in the primary conductor, in particular from a current source. The advantage here is that a high level of efficiency can be achieved with inductive transmission.

In an advantageous embodiment, the rectifier is a bridge rectifier formed from diodes,
wherein a first of the controllable switches is connected in parallel to a first of the diodes, wherein a second of the controllable switches is connected in parallel to a second of the diodes. The advantage here is that the rectifier can be implemented in a cost-effective and compact manner.

In an advantageous embodiment, the rectifier has two series circuits connected in parallel with one another, the first of the two series circuits having two diodes connected in series, a first of the two diodes being connected in parallel with a first of the controllable switches,
wherein the second of the two series circuits has two further diodes connected in series, with a first of the two further diodes being connected in parallel with a second of the controllable switches. The advantage here is that the rectifier can be implemented in a cost-effective and compact manner. Because there is no choke between the rectifier and the load, the voltage and current are made available to the load directly by the rectifier.

In an advantageous embodiment, each of the controllable switches is connected to a lower potential of the output voltage of the rectifier and/or the smoothing capacitor. The advantage here is that the short circuit occurs via the lower potential.

In an advantageous embodiment, the rectifier is designed as a synchronous rectifier and/or the rectifier has two series circuits connected in parallel with one another,
wherein the first of the two series circuits has two series-connected controllable switches,
the second of the two series circuits having two further controllable switches connected in series,
wherein a control unit supplies the control signals to the controllable switches, in particular as a function of the AC voltage side Connection of the rectifier applied voltage or depending on the input current of the rectifier,
in particular, the controllable switches being embodied as MOSFETs. The advantage here is that the state of the controllable switches is changed in time with the AC voltage, in particular when the current passes through zero. This results in the lowest possible losses.

In an advantageous embodiment, the load is supplied directly from the connection of the rectifier on the DC voltage side, that is to say without an interposed choke inductance. The advantage here is that a choke is not necessary and the system can therefore be designed to be compact.

In an advantageous embodiment, a control unit generates the control signals for the controllable switches,
wherein the system has a voltage sensor for detecting the voltage applied to the load and/or the output voltage of the rectifier and/or a current sensor for detecting the current exiting or entering the DC voltage-side connection of the rectifier,
wherein the control unit is connected to the voltage sensor and/or current sensor, in particular wherein the actual values detected by the voltage sensor and/or current sensor are fed to the control unit,
In particular, the control unit has a controller which generates the control signals as a function of the sensor signals from the voltage sensor and/or current sensor. The advantage is that

In an advantageous embodiment, the controller is a linear controller, in particular a PI controller, or a two-point controller. The advantage here is that an inexpensive controller can be used. The bang-bang controller already gives out a digital signal by itself, so that the controllable switches either perform the shorting or not. When using the linear controller, the output signal must still be discretized or digitized so that the duration of the short-circuiting corresponds to the discretized or digitized output signal.

In an advantageous embodiment, the control unit is designed in such a way that the state of the controllable switches is changed only when the current passes through zero of the alternating current impressed on the primary conductor. The advantage here is that the losses are small.

In an advantageous embodiment, the control unit is designed in such a way that the duration of the short-circuiting is an integral multiple of the period duration of the alternating current impressed into the primary conductor, in particular taking into account the dead time of the controllable switches. The advantage here is that the status changes take place in sync with the alternating current. Thus, the state change is carried out in the area of the zero crossing and a minimization of losses is thereby achieved.

In an advantageous embodiment, the controllable switches are controlled before and after the short-circuiting in such a way that the rectifier functions as a synchronous rectifier. The advantage here is that a particularly low-loss rectification can be carried out.

Important features of the method for operating a system are that the system has a rectifier that is fed from a resonant circuit and supplies a load, which has controllable switches with which the resonant circuit can be short-circuited, in particular can be short-circuited repeatedly over time,
wherein the controllable switches are controlled in such a way that the duration of the short-circuiting is an integer multiple of the period of the alternating current flowing in the resonant circuit, in particular or of the alternating current impressed in a primary conductor inductively coupled to a secondary winding of the resonant circuit, in particular taking into account the dead time of the controllable switches ,
the period of time being set, in particular by a controller, in such a way that the actual value of the voltage present at the connection of the rectifier on the DC voltage side is regulated towards a desired voltage value and/or the actual value of the current exiting or entering the connection of the rectifier on the DC voltage side is regulated towards a desired current value becomes.

The advantage here is that the rectifier itself can be used as an actuator and no choke is required between the rectifier and the load. A compact design can thus be achieved. In addition, low-loss operation can be achieved by switching in the area of the current zero crossing.

In an advantageous embodiment, the state of the controllable switch is changed only when the alternating current passes through zero. The advantage here is that low-loss operation can be achieved.

In an advantageous embodiment, before and after the short-circuiting, the load, in particular together with a smoothing device arranged on the DC-voltage-side connection of the rectifier capacitor, powered from the rectifier,
In particular, the rectifier, in particular the rectifier designed as a bridge rectifier, being operated as a synchronous rectifier. The advantage here is that rectification, in particular synchronous rectification, can be carried out before and after the short-circuiting, and a voltage corresponding to the ratio of short-circuiting to rectification can thus be made available to the load.

• - dass zum Aufladen des Energiespeichers der, insbesondere mit dem Stromsensor, erfasste Istwert des Wechselstroms auf den Stromsollwert hin geregelt wird, solange die am gleichspannungsseitigen Anschluss des Gleichrichters erfasste Spannung kleiner ist als ein vorgegebener Schwellwert, insbesondere Ladeschlussspannung,
• - und dass der am gleichspannungsseitigen Anschluss des Gleichrichters, insbesondere mit dem Spannungssensor, erfasste Istwert der Spannung auf den Spannungssollwert hin geregelt wird, solange die am gleichspannungsseitigen Anschluss des Gleichrichters erfasste Spannung größer ist als ein vorgegebener Schwellwert, insbesondere Ladeschlussspannung.

In an advantageous embodiment, the load is designed as an energy store and the rectifier, in particular the controllable switch of the rectifier, acts as an actuator of a charge controller, in particular is used as an actuator of a charge controller,
in particular where the duration is set such that

• - that for charging the energy store, the actual value of the alternating current, in particular with the current sensor, is regulated towards the current setpoint as long as the voltage recorded at the DC voltage-side connection of the rectifier is lower than a predetermined threshold value, in particular the end-of-charge voltage,
• - and that the actual value of the voltage detected at the DC voltage-side connection of the rectifier, in particular with the voltage sensor, is regulated towards the voltage setpoint as long as the voltage detected at the DC voltage-side connection of the rectifier is greater than a predetermined threshold value, in particular the end-of-charge voltage.

The advantage here is that the short-circuiting and the rectification always alternate and/or replace one another. The output voltage or the output current can thus be regulated to a respective desired value. In addition, rapid charging can be carried out with the regulation, which is followed by voltage-controlled charging. The rectifier thus functions together with the control unit as a charge controller, with the resonant circuit feeding the rectifier and making the choke unnecessary.

Further advantages result from the dependent claims. The invention is not limited to the combination of features of the claims. For the person skilled in the art, there are further meaningful combinations of claims and/or individual claim features and/or features of the description and/or the figures, in particular from the task and/or the task posed by comparison with the prior art.

• In der 1 ist der sekundärseitige Teil eines ersten Systems zur berührungslosen Energieübertragung an ein Mobilteil schematisch dargestellt.
• In der 2 sind zugehörige Ansteuersignale 20 beispielhaft dargestellt.
• In der 3 ist der sekundärseitige Teil eines zweiten Systems zur berührungslosen Energieübertragung an ein Mobilteil schematisch dargestellt.
• In der 4 sind zugehörige Ansteuersignale 20 beispielhaft dargestellt.

The invention will now be explained in more detail using schematic illustrations:

• In the 1 the secondary-side part of a first system for contactless energy transmission to a handset is shown schematically.
• In the 2 associated control signals 20 are shown as examples.
• In the 3 the secondary-side part of a second system for contactless energy transmission to a handset is shown schematically.
• In the 4 associated control signals 20 are shown as examples.

As in the 1 and 2 shown as an exemplary embodiment according to the invention, the system has a mobile part, in particular a vehicle, on the underside of which a secondary winding 1 is arranged, which is inductively coupled to an elongated line cable laid in a system, which is supplied with a medium-frequency alternating current, in particular with a frequency between 10 and 1000kHz.

For example, the line cable is laid in the floor of a facility if the vehicle can be moved on the floor of the facility, or is attached to a rail if the vehicle is a rail vehicle.

A capacitor 2 is connected in series to the secondary winding 1, with the capacitor 2 being dimensioned in such a way that the resonant frequency associated with the resonant circuit and/or oscillating circuit formed by the secondary winding 1 and the capacitor 2 corresponds to the frequency of the alternating current impressed on the line conductor functioning as the primary conductor equals.

A bridge rectifier is fed from the resonant circuit, the two half-bridges of which are each formed from a series connection of two diodes each. In a first of the half-bridges, diodes 6 and 10 are connected in series; in a second of the half-bridges, diodes 8 and 11 are connected in series.

On the output side, a smoothing capacitor 12 is connected to the bridge rectifier, to which the load 13 to be supplied, in particular consumers, is connected in parallel, so that the smoothing capacitor 12 and the load 13 are supplied directly from the bridge rectifier, in particular without an intermediate choke or the like. In this case, a first controllable switch 8 is connected in parallel with a diode 6 of the first half-bridge, which is connected to a lower output potential switched. Likewise, a second controllable switch 9 is connected in parallel with a diode 8 of the second half-bridge that is connected to the lower output potential

By closing the two controllable switches 7 and 9, the resonant circuit, in particular the oscillating circuit, is short-circuited.

When switches 7 and 9 are open, the bridge rectifier rectifies the AC voltage appearing in the resonant circuit.

The voltage across the smoothing capacitor 12 can thus be influenced by controlling the time span of the short-circuiting.

The current 20 flowing into the bridge rectifier is detected with a sensor 3 . The sensor signal is fed to a control unit 5, which generates the control signals for the controllable switches (8, 9).

The voltage U_z actual present at the smoothing capacitor 12 is detected and supplied to the control unit 5 as the actual value. The current I_z actual flowing to the load 13 is recorded and fed to the control unit 5 as an actual value.

The control signals 4 of the controllable Switches 7 and 9 created. Either a two-point controller or a linear controller, such as a PI controller, is used as the controller. The duration of the short-circuiting is set in time with complete periods of the alternating current 20 by means of the control signals 4 .

2 shows a schematic of an exemplary drive signal 4 and the current 20 that occurs and flows into the bridge rectifier.

It is important that the switches 7 and 9 are opened and closed in the area of the current zero crossing.

In order to keep the load on the secondary winding symmetrical, the state of the switch is changed only at the minimum time interval of the period duration of the current 20 emerging from the resonant circuit.

The control value determined by the controller is thus output in digitized form and only changed in time with whole periods of the alternating current 20 . The switches 7 and 9 are therefore only closed for a period of time which is equal to an integer multiple of the period of the alternating current, and then opened for a further period of time which in turn is equal to an integer multiple of the period.

Slight deviations from these time periods are only selected in order to take into account the dead time of the switches 7 and 9.

In a first exemplary embodiment, the regulator is designed as a mere voltage regulator. For this purpose, only the difference between the actual value U_z, actual and the desired value U_z, desired is supplied to the controller, from which the controller then determines the activation signal 4 .

In a second exemplary embodiment, the controller is designed as a mere current controller. For this purpose, only the difference between the actual value I_z, actual and the desired value I_z, desired is supplied to the controller, from which the controller then determines the activation signal 4 .

In a third exemplary embodiment, the controller is designed as a voltage controller with a subordinate current controller. For this purpose, the difference between actual value U_z, actual and desired value U_z, desired is supplied to the voltage regulator, from which the controller then determines control signal 4 . However, the setpoint U_z, setpoint is a control value of the current controller, to which the difference between actual value I_z, actual and setpoint I_z, setpoint is supplied.

In a fourth exemplary embodiment, load 13 is an energy store to be charged, in particular an accumulator or battery, and the charging process is first current-controlled by supplying the difference between actual value I_z,actual and setpoint value I_z,setpoint to a current controller, from which the current controller then determines control signal 4. At the same time, however, the actual value of the voltage U_z, ist is monitored for exceeding a threshold value, in particular the end-of-charge voltage, and when it is exceeded, voltage regulation is activated instead of current regulation, with the difference between the actual value U_z, actual and the setpoint value U_z, setpoint being fed to a voltage regulator, from which the regulator then the control signal 4 is determined. Thus, an initial fast charge can be followed by a slow, voltage-controlled, slower charge.

As in 3 shown, in contrast to the above embodiment, a synchronous rectifier consisting of the controllable switches (30, 31, 37, 39), in particular MOSFET, is used instead of the diodes (6, 7, 8, 9) and the switches (7, 9) composite rectifier of the embodiment 1 .

The synchronous rectifier has a first series connection made up of controllable switches 30 and 37, which is formed in parallel with the series connection made up of the controllable switches 31 and 39.

The control signals 4 of the switches (30, 31, 37, 39) are in turn formed by the control unit, which has a controller. The output signal of the controller is in turn formed only in time with whole periods of the alternating current, that is to say the secondary current 20 .

Examples are such control signals 4 in 4 shown. The alternating current 20 is shown in the top line.

The drive signal 40 for the controllable switch 30, in particular MOSFET, is shown in the penultimate line.

The drive signal 41 for the controllable switch 31, in particular MOSFET, is shown in the last line and the drive signal 47 for the controllable switch 37, in particular MOSFET, in the second line.
The control signal 49 for the controllable switch 39, in particular MOSFET, is shown in the third, in particular middle line.

In a first half-wave, the switches 31 and 37, ie the lower switch of the first half-bridge and the upper switch of the second half-bridge, are closed, ie in particular conductive, and the other two switches 30 and 39 are open, in particular taking into account the dead times of the switches ( 30, 31, 37, 39). In the area of the current zero crossing, the states of the switches (30, 31, 37, 39) are inverted, i.e. the switches 31 and 37 are opened and the upper switch 30 of the first half-bridge and the lower switch 39 of the second half-bridge are closed, in particular taking into account the Dead times of the switches (30, 31, 37, 39).

After the second half-wave, the two switches 37 and 39, that is to say the lower switches of the two half-bridges, are closed in order to cause a short-circuit KS in the resonant circuit.

Since the alternating current is impressed on the primary conductor, the behavior is similar to that of a current source. No further current is passed through to the smoothing capacitor 12 as a result of the short-circuiting.

The synchronous rectifier implemented by the switches (30, 31, 37, 39) is therefore not only used for rectifying, but also for short-circuiting the current source, so that the voltage across the smoothing capacitor 12 can be regulated.

The duration of the short circuit is equal to in 4 the temporal length of two periods of the alternating current 20, in particular ignoring the switching times of the switches (30, 31, 37, 39), which are slightly shifted because of the dead time.

After the short-circuit period, the synchronous rectification operation is continued.

It is also important that the load 13 and the smoothing capacitor 12 are supplied directly on the output side of the synchronous rectifier, ie not via an interposed inductance or the like. Nevertheless, a charge controller can be saved according to the invention. This is because the synchronous rectifier acts as a charge controller for a load that can be used as an energy store.

The advantage of using a resonant circuit is the high degree of efficiency in the inductive transfer of energy from the primary line to the secondary winding.

In further exemplary embodiments according to the invention, somewhat more lossy IGBTs are used instead of the MOSFETs.

Reference List

1

secondary winding

2

capacity

3

Current detection sensor

4

control signals

5

control unit

6

diode

7

controllable switch, in particular semiconductor switch

8th

diode

9

controllable switch, in particular semiconductor switch

10

diode

11

diode

12

smoothing capacitor

13

load, especially consumers

20

secondary current

30

controllable switch, in particular MOSFET

31

controllable switch, in particular MOSFET

37

controllable switch, in particular MOSFET

38

controllable switch, in particular MOSFET

40

Control signal for the controllable switch 30, in particular MOSFET

41

Control signal for the controllable switch 31, in particular MOSFET

47

Control signal for the controllable switch 37, in particular MOSFET

48

Control signal for the controllable switch 38, in particular MOSFET

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2740208 B1 [0002]

Claims (15)

System for contactless energy transmission from a primary conductor to a mobile part, the mobile part having a secondary winding, characterized in that a capacitance is connected in series or in parallel to form a resonant circuit of the secondary winding, with a rectifier being supplied from the resonant circuit, at the output of which a smoothing capacitor is arranged, to which a load, in particular a consumer, is connected in parallel, the rectifier having controllable switches with which the resonant circuit and/or the input of the rectifier can be short-circuited, in particular the resonant circuit feeding the AC voltage-side connection of the rectifier and the DC voltage side Connection of the smoothing capacitor is connected and / or the load is fed from the DC voltage side connection. system after claim 1 , characterized in that the mobile part can be moved on a floor and the secondary winding is arranged on a side of the mobile part facing the floor, in particular with the primary conductor being laid in an elongated manner in the floor or being arranged in the floor as a coil winding, or in that the mobile part is a rail vehicle , wherein the primary conductor can be moved along or parallel to a rail that can be driven on by the handset. System according to one of the preceding claims, characterized in that the resonant frequency of the resonant circuit formed from the secondary winding and the capacitance, in particular the oscillating circuit, is equal to the frequency of the alternating current impressed in the primary conductor, in particular from a current source. System according to one of the preceding claims, characterized in that the rectifier is a bridge rectifier formed from diodes, a first of the controllable switches being connected in parallel to a first of the diodes, a second of the controllable switches being connected in parallel to a second of the diodes, and/ or that the rectifier has two series circuits connected in parallel, with the first of the two series circuits having two diodes connected in series, with a first of the two diodes having a first of the controllable switches connected in parallel, with the second of the two series circuits having two more in series has switched diodes, a first of the two further diodes being connected in parallel with a second of the controllable switches. System according to one of the preceding claims, characterized in that each of the controllable switches is connected to a lower potential of the output voltage of the rectifier and/or the smoothing capacitor. system according to one of the Claims 1 until 3 , characterized in that the rectifier is designed as a synchronous rectifier and/or that the rectifier has two series circuits connected in parallel with one another, the first of the two series circuits having two controllable switches connected in series, the second of the two series circuits having two more series-connected switches has controllable switches, in particular wherein in particular wherein the controllable switches are designed as MOSFETs. System according to one of the preceding claims, characterized in that the load is supplied directly from the DC voltage-side connection of the rectifier, ie without an interposed choke inductance. System according to one of the preceding claims, characterized in that a control unit generates the control signals for the controllable switches, the system having a voltage sensor for detecting the voltage present at the load and/or the output voltage of the rectifier and/or a current sensor for detecting the current exiting or entering the DC voltage-side connection of the rectifier, the control unit being connected to the voltage sensor and/or current sensor, in particular the actual values detected by the voltage sensor and/or current sensor being fed to the control unit, in particular the control unit having a controller which Control signals generated depending on the sensor signals of the voltage sensor and / or current sensor. System according to one of the preceding claims, characterized in that the controller is a linear controller, in particular a PI controller, or a two-point controller. System according to one of the preceding claims, characterized in that the control unit is designed in such a way that the state of the controllable switches is changed only when the current passes through zero of the alternating current impressed on the primary conductor. System according to one of the preceding claims, characterized in that the control unit is designed in such a way that the duration of the short-circuiting is an integral multiple of the period duration of the alternating current impressed into the primary conductor, in particular taking into account the dead time of the controllable switches. system according to one of the Claims 6 until 11 , characterized in that before and after short-circuiting the controllable switches are controlled in such a way that the rectifier acts as a synchronous rectifier. Method for operating a system, in particular according to one of the preceding claims, in which the system has a rectifier fed from a resonant circuit and supplying a load, which has controllable switches with which the resonant circuit can be short-circuited, in particular can be short-circuited repeatedly, characterized in that the controllable switches are controlled in such a way that the duration of the short-circuiting is an integer multiple of the period of the alternating current flowing in the resonant circuit, in particular or the alternating current impressed in a primary conductor inductively coupled to a secondary winding of the resonant circuit, in particular taking into account the dead time of the controllable switches, the period of time being set, in particular by a regulator, in such a way that the actual value of the voltage present at the connection of the rectifier on the DC voltage side is regulated towards a desired voltage value and/or d he actual value of the current exiting or entering the connection of the rectifier on the DC voltage side is regulated to a desired current value. Method according to one of the preceding claims, characterized in that the state of the controllable switches is changed only when the alternating current passes through zero, in particular wherein each of the switches is only either in the open or closed state, and/or that before and after the short-circuiting the load, in particular together with a smoothing capacitor arranged on the DC voltage-side connection of the rectifier, from which the rectifier is supplied, in particular the rectifier, in particular the rectifier designed as a bridge rectifier, being operated as a synchronous rectifier. Method according to one of the preceding claims, characterized in that the load is designed as an energy store and the rectifier, in particular the controllable switches of the rectifier, act as an actuator of a charge controller, in particular are used, in particular the time period is set such that - that for charging of the energy store, the actual value of the alternating current recorded, in particular with the current sensor, is regulated towards the current setpoint as long as the voltage recorded at the connection of the rectifier on the DC voltage side is lower than a predetermined threshold value, in particular the end-of-charge voltage, - and that the voltage on the connection of the rectifier on the DC voltage side, in particular with the voltage sensor, the detected actual value of the voltage is regulated to the desired voltage value as long as the voltage detected at the DC voltage-side connection of the rectifier is greater than a predetermined threshold value, in particular charging end spa well.

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