Apparatus for controlling an ultrasonic transducer for generating ultrasonic waves

Abstract

An apparatus for controlling an ultrasonic transducer that generates ultrasonic waves is provided. [Solution] The device includes first and second low-side semiconductor switches 32, 34, each having a current path that can be switched between a conductive state and a non-conductive state, and the device further includes first and second high-side semiconductor switches 36, 38, each having a current path that can be switched between a conductive state and a non-conductive state. The current paths of the first low-side semiconductor switch 32 and the first high-side semiconductor switch 36 are interconnected. The current paths of the second low-side semiconductor switch 34 and the second high-side semiconductor switch 38 are also interconnected. A switch control unit 30 is used to alternately switch the semiconductor switches 32, 34, 36, 38 between a conductive state and a non-conductive state.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for controlling an ultrasonic transducer for generating ultrasonic waves. [Background technology]

[0002] This type of ultrasonic transducer is used, for example, to monitor the surroundings of a vehicle. For this purpose, multiple ultrasonic transducers are typically connected via a communications bus to a central control unit, which not only controls the ultrasonic transducers or their control devices but also evaluates the ultrasonic signals received from the ultrasonic transducers. Each ultrasonic transducer typically pre-processes the received ultrasonic signals with the help of its assigned electronics. In this respect, the ultrasonic transducer is essentially part of the ultrasonic sensor, providing not only the control unit but also the circuit components for pre-processing and, if necessary, partial evaluation of the electrical acoustic signal. These sensors can also perform self-tests and similar self-diagnostics.

[0003] For example, using an ultrasonic transducer to generate the ultrasonic waves at the required acoustic pressure to monitor a vehicle's surroundings typically requires a significant amount of energy and power to control the ultrasonic transducer. Therefore, ultrasonic transducers are controlled via a transformer. One advantage of this is that the voltage capability of the integrated circuit components typically used in ultrasonic sensors can be relatively low, because the ultrasonic transducer's voltage is transformed upward via a transformer.

[0004] In the prior art, it is known to alternately connect the primary coil of a transformer for controlling an ultrasonic transducer to a common potential or a current source via one of two semiconductor switches (e.g., transistors). The current paths of these two semiconductor switches are alternately controlled in opposite directions via a control unit. The primary coil also has a center tap connected to a power supply potential. By alternately controlling the two semiconductor switches in opposite directions, the direction of current alternates in the primary coil, flowing through the primary coil between one of the primary terminals and the center tap. The switching drive voltage (also called AC drive voltage) required for an ultrasonic transducer (see, for example, EP-A-2189808) can be obtained at the secondary terminals by selecting an appropriate transmission ratio of the transformer.

[0005] Designing a transformer with a center tap on the primary requires some effort because it requires two windings (coils) and the connection between them must be brought out as the center tap. The center tap requires an additional terminal on the IC. All of this increases the manufacturing and / or assembly costs of the ultrasonic sensor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent Application Publication No. 2189808 (EP-A-2189808) Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide a remedy in this regard and to provide a simplified construction and connection of an ultrasonic transducer. [Means for solving the problem]

[0008] To this end, the present invention provides an apparatus for controlling an ultrasonic transducer that generates ultrasonic waves, the apparatus comprising: a transformer having first and second primary terminals (having a primary coil between these terminals) and two secondary terminals (having a secondary coil between these terminals) to which an ultrasonic transducer can be connected; first and second low-side semiconductor switches, each having a current path switchable to either a conducting state or a non-conducting state; first and second low-side semiconductor switches, the current path of the first low-side semiconductor switch being arranged between a first circuit node common to the two low-side semiconductor switches and a first primary terminal of a transformer, and the current path of the second low-side semiconductor switch being arranged between the first circuit node and a second primary terminal of the transformer; first and second low-side semiconductor switches, each having a current path switchable to either a conducting state or a non-conducting state; a current path of the first high-side semiconductor switch is arranged between a first primary terminal of a transformer and a second circuit node common to the two high-side semiconductor switches, and a current path of the second high-side semiconductor switch is arranged between a second primary terminal of the transformer and a second circuit node; first and second high-side semiconductor switches, each having two terminals and an energy source connectable directly or indirectly to two circuit nodes; A switch control unit that alternately switches the high-side semiconductor switch and the low-side semiconductor switch between a conductive state and a non-conductive state, a switch control unit that, in one control phase of a control cycle, switches the first high-side semiconductor switch and the second low-side semiconductor switch to a conductive state and switches the second high-side semiconductor switch and the first low-side semiconductor switch to a non-conductive state, and, in another control phase of the control cycle, switches the second high-side semiconductor switch and the first low-side semiconductor switch to a conductive state and switches the first high-side semiconductor switch and the second low-side semiconductor switch to a non-conductive state, so that current alternately flows in reverse directions through the primary terminals and the primary coil of the transformer; It is equipped with:

[0009] The starting point of the present invention, which improves ultrasonic transducer control by simplifying transformer design, is the known connection of two primary terminals of a transformer to respective semiconductor switches, hereinafter referred to as low-side semiconductor switches, with current paths leading from a common first circuit node to the two primary terminals. Furthermore, according to the present invention, two high-side semiconductor switches are connected to the two primary terminals of the transformer, with current paths leading from the two primary terminals of the transformer to a common second circuit node. The current paths of all semiconductor switches, typically transistors, are alternately switchable between a conducting and non-conducting state, meaning that current flows alternately in opposite directions through the primary terminals of the transformer and through a primary coil arranged between two series circuits consisting of the low-side and high-side semiconductor switches.

[0010] The present invention relates to two parallel-connected series circuits, each consisting of two semiconductor switches. The first series circuit has a current path between a first low-side semiconductor switch and a first high-side semiconductor switch, and the second series circuit has a current path between a second low-side semiconductor switch and a second high-side semiconductor switch. The primary terminals of the transformer are connected to the connection nodes between the current paths of the two semiconductor switches in each series connection. The current paths of the four semiconductor switches are controlled such that, during one control phase of a control cycle, the switch control unit switches the first high-side semiconductor switch and the second low-side semiconductor switch to a conductive state and the second high-side semiconductor switch and the first low-side semiconductor switch to a non-conductive state, and during another control phase of the control cycle, the second high-side semiconductor switch and the first low-side semiconductor switch to a conductive state and the first high-side semiconductor switch to a non-conductive state. In this case, current alternately flows in opposite directions through the primary terminals of the transformer, and thus through its primary coil.

[0011] The main advantage of this invention is that it simplifies the transformer design by eliminating the center tap of the primary coil and requiring only one (single) winding or coil on the primary side, further saving terminals on the IC.

[0012] In an advantageous embodiment of the present invention, the device further includes a current source that sets the current flowing through the current paths of the high-side semiconductor switch and the low-side semiconductor switch to their respective conductive end states. The current source is disposed between the first circuit node and one terminal of the energy source or between the second circuit node and the other terminal of the energy source. The current source can be used to set the current flowing through the current paths of the semiconductor switches. This is particularly advantageous when multiple ultrasonic transducers are used to monitor the surroundings of a vehicle, as is typically the case. Due to manufacturing tolerances of ultrasonic transducers and transformers, it is not necessarily guaranteed that all transducers will emit ultrasonic waves of the same sound pressure when connected to the vehicle's electrical system. However, this is advantageous for reliably monitoring the surroundings of the vehicle. Therefore, by adjusting the current source, each ultrasonic transducer can be controlled so that all ultrasonic transducers emit sound waves of essentially the same sound pressure.

[0013] The current source for each ultrasonic transducer used advantageously in this respect can now be connected either to the current path of a high-side semiconductor switch (so-called high-side current source) or to the current path of a low-side semiconductor switch (so-called low-side current source). In both cases, the current source is therefore connected to one of two circuit nodes, the other of which is, for example, connected to ground potential when the current source is used as a high-side current source, or to the power supply potential of the vehicle electrical system when the current source is used as a low-side current source.

[0014] The control of the primary side of the transformer according to the present invention, combined with its higher supply voltage, results in a reduction / halving of the current compared to transformers with a center tap on the primary side, and the semiconductor switches used need to be significantly smaller, resulting in a smaller chip area. Furthermore, space is saved for the high-voltage IC pins of the center tap. Finally, diagnostics of the control unit are simplified. Regarding the simplification of the transformer, the present invention allows the omission of two primary windings / coils, and the use of a single coil instead.

[0015] For OEM suppliers of ultrasonic sensors and individual sensor modules, further benefits include simplified wiring on the PCB, since only two wires are required from the IC to the transformer (instead of the three previously required at the transformer's center tap). The aforementioned halving of the current also means reduced resistive losses, which means less power loss and allows the transformer to operate more efficiently. Considering the fact that currently used transformers already reach inductive saturation at higher currents (around 500 mA), halving the current gives suppliers considerable leeway. Halving the current also reduces EMC emissions on the supply lines.

[0016] However, suppliers can also use the control system according to the invention without changing the design of previously used transformers. For this purpose, the center tap no longer needs to be connected to the control unit, and the two "outer" primary connections are connected to the control unit. This procedure applies in particular when the transmission ratio is halved (for example, 1:5 instead of 1:10). However, suppliers also have the option of using optimized transformers that do not require a center tap on the primary side. This reduces the manufacturing costs of the transformer.

[0017] In this regard, in order to achieve the above object, according to the present invention, a control device comprises: first and second low-side semiconductor switches, each having a current path switchable between a conductive state and a non-conductive state; first and second low-side semiconductor switches, the current path of the first low-side semiconductor switch being arranged between a first circuit node common to the two low-side semiconductor switches and a first output terminal connectable to a first primary terminal of a transformer connected to an ultrasonic transducer, and the current path of the second low-side semiconductor switch being arranged between the first circuit node and a second output terminal connectable to a second primary terminal of the ultrasonic transducer; first and second low-side semiconductor switches, each having a current path switchable between a conductive state and a non-conductive state; a current path of the first high-side semiconductor switch is arranged between a second circuit node common to the two high-side semiconductor switches and the first output terminal, and a current path of the second high-side semiconductor switch is arranged between the second circuit node and the second output terminal; first and second high-side semiconductor switches, each having two terminals and an energy source connectable directly or indirectly to two circuit nodes; A switch control unit that alternately switches a high-side semiconductor switch and a low-side semiconductor switch between a conductive state and a non-conductive state, a switch control unit that switches the first high-side semiconductor switch and the second low-side semiconductor switch to a conductive state and switches the second high-side semiconductor switch and the first low-side semiconductor switch to a non-conductive state during one control phase of a control cycle, and switches the second high-side semiconductor switch and the first low-side semiconductor switch to a conductive state and switches the first high-side semiconductor switch to a non-conductive state during another control phase of the control cycle; It is alternatively proposed to comprise [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The figure (FIG. 1) shows one embodiment of the present invention. The overall structure of an ultrasonic sensor 10 is shown diagrammatically, comprising an ultrasonic transducer 12, a transformer 14 that supplies energy to the ultrasonic transducer 12, and a control unit 16 designed as an IC.

[0020] The transformer 14 has a first primary terminal 18 and a second primary terminal 20, between which a primary coil or winding 22 is disposed. On the secondary side, the transformer 14 has a first terminal 24 and a second terminal 26, between which a secondary coil or winding 28 is disposed. The two secondary terminals 24, 26 are connected to the TR- and TR+ terminals of the ultrasonic transducer 12.

[0021] Part of the control unit 16 is a switch control unit 30 for switching the line and block ends of a total of four semiconductor switches. In this case, the current path of a first low-side semiconductor switch 32 is connected to the current path of a first high-side semiconductor switch 36 to form a first series circuit 40, and the current path of a second low-side semiconductor switch 34 is connected to the current path of a second high-side semiconductor switch 38 to form a second series circuit 42. Both series circuits are connected between a supply potential VBAT and, in this embodiment, a current source 44, which is connected to a second voltage potential GND. The two low-side semiconductor switches 32 and 34 are connected to a first circuit node 45, and the two high-side semiconductor switches 36 and 38 are connected to a second circuit node 46. A connection node 48 of the two semiconductor switches of the first series circuit 40 is connected to the first primary terminal 18 of the transformer 14 as the outward-wired terminal DRV1 of the control unit 16. Similarly, the connection node 50 of the semiconductor switches of the second series circuit 42 is connected to the second primary terminal 20 of the transformer 14 as outwardly wired terminal DRV2.

[0022] The figure also shows that the two terminals TR+ and TR- of the ultrasonic transducer 12 are connected to two terminals AINS and ANG of the control unit 16. Via these two IC terminals, the electrical receive signals generated by the ultrasonic transducer in response to received echoes reach circuit components not shown for pre-processing of the receive signals, after which they are routed externally via other IC terminals (e.g. for communication and external control) I / O and I / O_, for example via a communication bus 52 to a central control and evaluation unit 54.

[0023] Although not shown in the figures, there are external and internal components that ensure the isolation of the high voltage control signals and the low voltage receive signals of the ultrasonic transducer. Such measures and circuit components are generally known in connection with the operation of ultrasonic transducers and therefore need not be described further here.

[0024] The present invention has been described above with a transformer as a component of a control device for an ultrasonic transducer. However, the present invention may be implemented without reference to a transformer. In this respect, the present invention relates to a control device for an ultrasonic transducer for generating ultrasonic waves, the control device comprising the four semiconductor switches interconnected as described above, and a switch control unit for alternately switching the semiconductor switches between a conductive state and a non-conductive state as described above. [Explanation of symbols]

[0025] 10 sensors 12 Ultrasonic transducer 14 Transformer 16 Control section (IC) 18 First primary terminal 20 Second primary terminal 22 Primary coil or winding 24 First secondary terminal 26 Second secondary terminal 28 Secondary coil or winding 30 Switch control section 32 First low-side semiconductor switch 34 Second low-side semiconductor switch 36 First high-side semiconductor switch 38 Second high-side semiconductor switch 40, 42 series connection 44 Energy Supply 45 First Circuit Node 46 Second Circuit Node 48, 50 connected nodes 52 Communication Bus 54 Central Control and Evaluation Department DRV1 First output terminal DRV2 Second output terminal AINS, AING receiving signal terminal I / O_, I / O communication bus terminal VBAT Power supply potential GND Power supply ground potential

Claims

1. a transformer (14) having first and second primary terminals (18, 20) and two secondary terminals (24, 26) to which an ultrasonic transducer (12) can be connected; first and second low-side semiconductor switches (32, 34) each having a current path switchable to either a conducting state or a non-conducting state; first and second low-side semiconductor switches (32, 34), the current path of the first low-side semiconductor switch (32) being arranged between a first circuit node (45) common to the two low-side semiconductor switches (32, 34) and the first primary terminal (18) of the transformer (14), and the current path of the second low-side semiconductor switch (34) being arranged between the first circuit node (45) and the second primary terminal (20) of the transformer (14); first and second high-side semiconductor switches (36, 38) each having a current path switchable to either a conducting or non-conducting state; the current path of the first high-side semiconductor switch (36) is arranged between a second circuit node (46) common to the two high-side semiconductor switches (36, 38) and the first primary terminal (18) of the transformer (14), and the current path of the second high-side semiconductor switch (38) is arranged between the second circuit node (46) and the second primary terminal (20) of the transformer (14); first and second high-side semiconductor switches (36, 38) having two terminals, and an energy source (VBAT, GND) connectable directly or indirectly to the two circuit nodes (45, 46); a switch control unit that alternately switches the high-side semiconductor switches (36, 38) and the low-side semiconductor switches (32, 34) between a conductive state and a non-conductive state, a switch control unit (30) that, during one control phase of a control cycle, switches the first high-side semiconductor switch (36) and the second low-side semiconductor switch (34) to a conductive state and switches the second high-side semiconductor switch (38) and the first low-side semiconductor switch (32) to a non-conductive state, and, during another control phase of the control cycle, switches the second high-side semiconductor switch (38) and the first low-side semiconductor switch (32) to a conductive state and switches the first high-side semiconductor switch (36) and the second low-side semiconductor switch (34) to a non-conductive state; An apparatus for controlling an ultrasonic transducer (12) for generating ultrasonic waves, comprising:

2. first and second low-side semiconductor switches (32, 34) each having a current path switchable to either a conducting state or a non-conducting state; first and second low-side semiconductor switches (32, 34), the current path of the first low-side semiconductor switch (32) being arranged between a first circuit node (45) common to the two low-side semiconductor switches (32, 34) and a first output terminal (DVR1) connectable to a first primary terminal (18) of a transformer (14) connected to the ultrasonic transducer (12), and the current path of the second low-side semiconductor switch (34) being arranged between the first circuit node (45) and a second output terminal (DRV2) connectable to a second primary terminal (20) of the transformer (14); first and second high-side semiconductor switches (36, 38) each having a current path switchable to either a conducting or non-conducting state; the current path of the first high-side semiconductor switch (36) is arranged between a second circuit node (46) common to the two high-side semiconductor switches (36, 38) and the first output terminal (DRV1), and the current path of the second high-side semiconductor switch (38) is arranged between the second circuit node (46) and the second terminal (DRV2); first and second high-side semiconductor switches (36, 38) having two terminals, and an energy source (VBAT, GND) connectable directly or indirectly to the two circuit nodes (45, 46); a switch control unit that alternately switches the high-side semiconductor switches (36, 38) and the low-side semiconductor switches (32, 34) between a conductive state and a non-conductive state, a switch control unit (30) that, during one control phase of a control cycle, switches the first high-side semiconductor switch (36) and the second low-side semiconductor switch (34) to a conductive state and switches the second high-side semiconductor switch (38) and the first low-side semiconductor switch (32) to a non-conductive state, and, during another control phase of the control cycle, switches the second high-side semiconductor switch (38) and the first low-side semiconductor switch (32) to a conductive state and switches the first high-side semiconductor switch (36) and the second low-side semiconductor switch (34) to a non-conductive state; An apparatus for controlling an ultrasonic transducer (12) for generating ultrasonic waves, comprising:

3. 3. The device according to claim 1, further comprising a current source (44) that sets the currents flowing through the current paths of the high-side semiconductor switches (36, 38) and the low-side semiconductor switches (32, 34) to their respective conductive end states, the current source (44) being arranged between the first circuit node (45) and one terminal of the energy source (VBAT, GND) or between the second circuit node (46) and the other terminal of the energy source (VBAT, GND).

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