Drive device for driving an electric motor of an electronic lock

Abstract

A drive device (1) for driving an electric motor of an electronic lock is described herein, comprising: a bridge rectifier circuit (10) comprising at least one pair of switching device bridge arms (110) electrically connected in a bridge arrangement, the switching device bridge arms (110) being connected at an input side to two bridge inputs (101) of the bridge rectifier circuit, respectively accessing a battery voltage of different polarity, and being connected at an output side to a bridge output (102) of the bridge rectifier circuit; and a drive circuit (20) electrically connected upstream to the bridge rectifier circuit and downstream to the electric motor, the drive circuit (20) comprising: an electric motor drive device (21); and a polarity switching circuit (22) comprising a switching device (221), and the switching device being connected at an input side to two second inputs (222), respectively accessing a second voltage of different polarity, and being connected at an output side to the electric motor drive device.

Description

Technical Field

[0001] This disclosure relates to the field of on-board charging devices for new energy vehicles, and in particular to a drive device for driving a motor of an electronic lock, and more specifically, to a drive device for driving a motor of an electronic lock for a charging gun of a new energy vehicle. Background Technology

[0002] Currently, new energy electric vehicles have become a global trend in the transportation industry. Electric vehicles are equipped with charging docks, which work in conjunction with charging guns to charge the vehicle's battery. Electronic locks are currently a crucial functional component in new energy vehicle charging, typically integrated as a separate module within the charging interface product. They are used to ensure the charging gun is locked during charging, preventing safety issues. Specifically, as an example, current applications of electronic lock drives in electric vehicle charging typically employ independent drive circuits to lock and release the electronic lock. That is, a drive signal is given during charging to lock the charging gun securely to the charging dock; a drive signal is given after charging is complete to release the charging gun, allowing it to be removed.

[0003] Based on the control characteristics of electronic locks, an independent drive circuit is designed for each lock. The charging controller controls the operation of the electronic lock through this drive circuit. Currently, most drive circuits use dual-channel switching signals. At present, the drive circuit for the motor of electronic locks is typically powered by ±12V DC. With the application of 48V power supply devices, customers are placing higher demands on the power supply range of electronic locks.

[0004] In electronic lock applications using a 48V power supply, there are two approaches to utilizing the motor. For example, one could choose to power the electronic lock with a 48V DC-powered motor. However, it's important to consider that a 48V DC-powered motor would be very large and unsuitable for assembly and design with existing charging interface products. As an alternative, an adapter circuit can be designed to adapt a 12V DC-powered motor to a 48V power supply.

[0005] Therefore, in the existing technology, there is an urgent need for an improved drive device for driving the motor of the electronic lock of the charging gun of new energy vehicles. Specifically, this can be achieved by improving the circuit design to adapt the 12V DC power supply to the 48V power supply, without changing the electronic lock itself. The compatibility problem between the 48V DC power supply and the 12V DC power supply can be solved simply by designing the peripheral connection circuit. Utility Model Content

[0006] The purpose of this disclosure is to solve at least one aspect of the aforementioned problems and defects in the prior art by providing a simple drive device for driving the motor of the electronic lock of the charging gun of a new energy vehicle, which is achieved, for example, by improving the circuit design by adapting the 12V DC-powered motor to a 48V power supply through an adapter circuit for driving the motor.

[0007] To achieve the above objectives, this disclosure provides the following technical solution:

[0008] In a first aspect of this disclosure, a drive device for driving a motor of an electronic lock is provided. The drive device includes: a bridge rectifier circuit including at least a pair of switching device arms electrically connected in a bridge arrangement, the switching device arms being connected at the input side to two bridge input terminals of the bridge rectifier circuit respectively connected to battery voltages of different polarities, and at the output side to a bridge output terminal of the bridge rectifier circuit; and a drive circuit electrically connected upstream to the bridge rectifier circuit and downstream to the motor, including: a motor driving device; and a polarity switching circuit including switching devices, wherein the switching devices are connected at the input side to two second input terminals respectively connected to second voltages of different polarities, and at the output side to the motor driving device.

[0009] In an exemplary embodiment, the bridge rectifier circuit includes a full-bridge rectifier circuit, which includes two pairs of bridge arms connected in parallel. Each pair of bridge arms includes a front bridge arm and a rear bridge arm connected in series. Each bridge arm has a corresponding diode and is electrically connected to the corresponding bridge input terminal at the intermediate node between the front bridge arm and the rear bridge arm in each pair of bridge arms connected in series. The bridge output terminal is electrically connected at the parallel connection of the respective rear bridge arms of the two pairs of bridge arms.

[0010] In an exemplary embodiment, the driving device further includes a DC-DC buck converter circuit, which is electrically connected between the bridge rectifier circuit and the driving circuit. The voltage input pin of the DC-DC buck converter circuit is connected to the bridge output terminal, and the voltage output pin of the DC-DC buck converter circuit is connected to the power supply pin of the driving circuit.

[0011] In an exemplary embodiment, the DC buck converter circuit is a synchronous buck DC-DC converter IC with integrated MOSFETs.

[0012] In an exemplary embodiment, the polarity switching circuit includes two discrete unipolar detection circuits, each unipolar detection circuit including a MOS switch and a resistor network electrically connected to each other, and the respective MOS switch of each unipolar detection circuit is electrically connected to the respective bridge input terminal of the bridge rectifier circuit with its gate, electrically connected to the voltage output pin of the DC buck converter circuit with its source, and grounded with its drain.

[0013] In an exemplary embodiment, the motor driving device includes an H-bridge rectifier circuit, which is connected to the output terminal of the DC buck converter circuit via the power supply pin and electrically connected to the motor via the output pin.

[0014] In an exemplary embodiment, the H-bridge rectifier circuit is an H-bridge motor driver IC and includes four N-channel power MOSFETs and an internal charge pump configured to generate a gate drive voltage.

[0015] In an exemplary embodiment, each unipolar detection circuit further includes a logic pin connected to the source of the corresponding MOS switch; and the H-bridge rectifier circuit is electrically connected to the corresponding logic pin of each unipolar detection circuit at each of the two enable pins.

[0016] In an exemplary embodiment, the bridge rectifier circuit includes two parallel half-bridge rectifier circuits, each half-bridge rectifier circuit being connected to the corresponding polarity of the bipolar input DC.

[0017] In an exemplary embodiment, the polarity switching circuit includes a pair of high-side switches, and the bridge rectifier circuit is connected to the motor via the connected high-side switches. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate certain aspects of the subject matter disclosed herein and, together with the description, help to explain some principles associated with the disclosed embodiments. In the drawings:

[0019] Figure 1 A schematic block diagram of an exemplary drive device for driving a motor of an electronic lock according to an embodiment of the present disclosure is shown.

[0020] Figures 2 to 4 A schematic circuit diagram of various sub-circuits in an exemplary drive device for driving a motor of an electronic lock according to an embodiment of the present disclosure is shown. Specifically, Figure 2 As shown Figure 1 A schematic circuit diagram of the bridge rectifier circuit and the DC buck converter circuit in the drive device is shown schematically. Figure 3 As shown Figure 1 A schematic circuit diagram of the polarity switching circuit in the drive device is shown schematically; and Figure 4 As shown Figure 1 A schematic circuit diagram of the motor driving device (shown as an H-bridge motor driver chip) and its peripheral circuitry in the drive unit is shown.

[0021] Figure 5 As shown Figure 3 The diagram shows a schematic circuit connection diagram of the polarity switching circuit. Detailed Implementation

[0022] This disclosure will now be described in detail with reference to the accompanying drawings, which are provided as illustrative examples to enable those skilled in the art to practice this disclosure. It is important to note that the following drawings and examples are not intended to limit the scope of this disclosure to a single embodiment, but rather to enable other embodiments by means of interchange of some or all of the described or illustrated elements. Furthermore, where certain elements of this disclosure can be implemented using known components in part or entirely, only those portions of such known components necessary for understanding this disclosure will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure this disclosure. Unless otherwise stated herein, it will be understood by those skilled in the art that embodiments described as being implemented in software are not intended to be limited to this, but may include embodiments implemented in hardware or a combination of software and hardware, and vice versa. Embodiments showing a singular number of components in this specification should not be considered limiting; rather, unless expressly stated otherwise herein, this disclosure is intended to cover other embodiments including a plurality of identical components, and vice versa. Furthermore, the applicant does not intend for any terminology in this specification or claims to be relegated to an uncommon or particular meaning unless so expressly stated. In addition, this disclosure covers current and future known equivalents of known components mentioned herein with the aid of illustrations.

[0023] Unless otherwise specified, the terms "bottom" and "top," "upper" and "lower," etc., used in this disclosure are relative concepts. Furthermore, the terms "corresponding" or "corresponding" in this disclosure refer to the correspondence between paired, collaboratively working components.

[0024] Figure 1 A schematic block diagram of an exemplary drive device 1 for driving a motor of an electronic lock according to an embodiment of the present disclosure is shown. Figures 2 to 4 A schematic circuit diagram of various sub-circuits in an exemplary drive device 1 for driving a motor of an electronic lock according to an embodiment of the present disclosure is shown. Specifically, Figure 2 As shown Figure 1A schematic circuit diagram of the bridge rectifier circuit 10 and the DC buck converter circuit 23 in the drive device 1 is shown. Figure 3 As shown Figure 1 A schematic circuit diagram of the polarity switching circuit 22 in the drive device 1 is shown schematically; and Figure 4 As shown Figure 1 A schematic circuit diagram of the motor drive device 21 and its peripheral circuits in the drive device 1 is shown.

[0025] In one aspect of this disclosure, based on the overall technical concept of this disclosure, such as Figures 1 to 4 As shown, a drive device 1 for driving a motor of an electronic lock is provided. The drive device 1 includes a bridge rectifier circuit 10, including at least a pair of switching device bridge arms 110 electrically connected in a bridge arrangement. The switching device bridge arms 110 are connected at the input side to two bridge input terminals 101 of the bridge rectifier circuit 10, which are respectively connected to battery voltages of different polarities (VBAT+ and VBAT- as shown, preferably ±48V, for example), and at the output side to a bridge output terminal 102 of the bridge rectifier circuit 10. The bridge rectifier circuit 10 is configured to respond to the battery voltages of different polarities (respectively connected at the two bridge input terminals 101) at the bridge output terminal 102. The circuit provides at least one unipolar first output voltage (typically one, such as +48V, as shown in the figure); and a drive circuit 20, electrically connected upstream to the bridge rectifier circuit 10 and downstream to the motor, including: a motor drive device 21; and a polarity switching circuit 22, including a switching device 221, wherein the switching device 221 is connected on the input side to two second input terminals 222 respectively connected to a second voltage of different polarities (for example, these two second input terminals 222 serve as a pair of polarity control signal input ports of the polarity switching circuit 22, such as VBAT+ and VBAT- as shown in the figure, preferably, for example, ±48V), and is connected on the output side to the motor drive device 21.

[0026] In a specific embodiment, as an example, each switching device bridge arm is a bridge arm that includes a unidirectional switching device. More specifically, for example, each switching device bridge arm is a bridge arm that includes a diode.

[0027] As an example, the polarity switching circuit 22 is configured to switch the operation of the motor in response to the second voltages of different polarities (as a pair of polarity control signals) provided at the two second input terminals 222 respectively, according to the switching timing between the pair of polarity control signals.

[0028] This setup allows for improvements in circuit design, such as adapting a motor with relatively low DC power requirements (e.g., ±12V) to a relatively high voltage (e.g., ±48V) power supply by designing an adapter circuit for driving the motor. This solves the problem of direct voltage matching between the DC power supply and the DC-powered motor without altering the electronic lock itself, simply through the design of the external connection circuit.

[0029] In exemplary embodiments of this disclosure, for example, as Figure 2 As shown, the bridge rectifier circuit 10 includes a full-bridge rectifier circuit 11, which includes two pairs of bridge arms 110 connected in parallel. Each pair of bridge arms 110 includes a front bridge arm 111 and a rear bridge arm 112 connected in series, and each bridge arm 110 has a corresponding diode 113. The intermediate node between the front bridge arm 111 and the rear bridge arm 112 of each pair of bridge arms 110 is electrically connected to a corresponding bridge input terminal 101 (e.g., a corresponding bipolar input DC voltage is connected to the corresponding bridge input terminal 101), and the parallel connection of the respective rear bridge arms 112 of the two pairs of bridge arms 110 is electrically connected to the bridged output terminal 102.

[0030] With this configuration, a pair of battery voltages of relatively high magnitudes (e.g., ±48V) can be converted into a first output voltage of unipolarity, for example, only positive but with a magnitude that remains constant (e.g., +48V), through a simple circuit such as a bridge rectifier circuit 10 in the form of a full-bridge rectifier circuit 11. Essentially, for example, for the input from VBAT+, it is electrically connected to the bridge output terminal 102 via the illustrated diode 113, such as D4, thereby producing a +48V output; and for the input from VBAT-, it is electrically connected to the bridge output terminal 102 via the illustrated diode 113, such as D5, thereby producing a +48V output. Both diodes 113, such as D3 and D6, are always in the off state.

[0031] In exemplary embodiments of this disclosure, such as Figure 2As shown as an example, the drive device 1 further includes a DC-DC buck converter circuit 23, comprising a buck DC-DC converter in the form of an integrated circuit chip, such as a synchronous buck DC / DC converter. As an example, the DC-DC buck converter circuit 23 is electrically connected between the bridge rectifier circuit 10 and the drive circuit 20, and the voltage input pin VIN of the DC-DC buck converter circuit 23 is connected to the bridge output terminal 102, and the voltage output pin BIAS of the DC-DC buck converter circuit 23 is connected to the power supply pin 200 of the drive circuit 20. Specifically, as an example, the DC-DC buck converter circuit 23 is configured to voltage-convert a first output voltage of single polarity from the bridge output terminal 102 of the bridge rectifier circuit 10 to obtain a second output DC voltage of single polarity at the output terminal of the DC-DC buck converter circuit 23 having a different magnitude from the battery voltage.

[0032] As a further example, the DC buck converter circuit 23 is a synchronous buck DC-DC converter IC with integrated MOSFETs. As shown in the figure, the DC buck converter circuit 23 is a buck DC-DC converter in the form of an integrated circuit chip, such as a synchronous buck DC-DC converter with integrated upper / lower MOSFETs (HS-FET and LS-FET, respectively).

[0033] With this setup, DC-DC buck conversion is achieved, for example, through a DC-DC buck converter circuit 23 in the form of an integrated IC. This allows for the selection of matching peripheral circuits based on the integrated chip to convert a relatively high DC voltage to a relatively low DC voltage, such as converting a +48V power supply to +12V. A high DC / DC efficiency ratio is achieved, typically exceeding 90%.

[0034] Figure 5 As shown Figure 3 The schematic circuit component connection diagram of the polarity switching circuit 22 shown is shown.

[0035] In exemplary embodiments of this disclosure, such as Figure 3 and Figure 5As shown as an example, the polarity switching circuit 22 includes two discrete unipolar detection circuits 220, each unipolar detection circuit 220 including a MOS switch 223 and a resistor network electrically connected to each other. The MOS switch 223 is, for example, an N-type resistor generated by DIODES widely used in power management and switching circuits. The circuit consists of a channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor); and each unipolar detection circuit 220 has its corresponding MOS switch 223 electrically connected at its gate 224 to the corresponding bridge input 101 of the bridge rectifier circuit 10 (e.g., the inputs of the unipolar detection circuit 220 connected to the gate 224 of the switching device 221 are respectively electrically connected to the corresponding polarity of the bipolar input DC, i.e., the inputs of the unipolar detection circuit 220 are, for example, VBAT+ and VBAT- as shown in the figure, preferably ±48V), at its source 225 to the voltage output pin BIAS of the DC buck converter circuit 23 (e.g., +12V as shown in the figure, and the source 225 is then electrically connected to the logic control pins of the downstream motor driver device 21 for switching the drive state of the motor, the logic control pins being IN1 and IN2 as shown in the figure, and the signals from the source 225 to the logic control pins being IN1 Input and IN2 Input as shown in the figure), and grounded at its drain 226.

[0036] With this setup, the polarity switching circuit 22, in the form of two separate unipolar detection circuits 220, can output a corresponding enable signal for logic control to the downstream motor drive device 21.

[0037] In exemplary embodiments of this disclosure, such as Figure 4 As shown as an example, the motor driving device 21 includes an H-bridge rectifier circuit, and the H-bridge rectifier circuit 210 is connected to the output terminal of the DC-DC buck converter circuit 23 via the power supply pin 200 to receive the converted voltage, for example 12V, from the DC-DC buck converter circuit 23 as a power supply voltage matching the specifications of the H-bridge rectifier circuit 210; and the H-bridge rectifier circuit 210 is electrically connected to the motor via the output pin to drive the motor.

[0038] In a further example, as shown in the figure, the H-bridge rectifier circuit is an H-bridge motor driver IC, and the H-bridge motor driver IC includes, for example, four N-channel power MOSFETs and an internal charge pump configured to generate a gate 224 drive voltage.

[0039] In a further exemplary embodiment, for example, as Figure 3 and Figure 5As shown, each unipolar detection circuit 220 also includes a logic pin 227 connected to the source 225 of the corresponding MOS switch 223; and the H-bridge rectifier circuit 210 is electrically connected to the corresponding logic pin 227 of each of the two enable pins IN1 and IN2. Furthermore, as shown in Table 1, the H-bridge rectifier circuit 210 is configured to provide a final-stage output voltage that switches between bipolarity at its output to achieve different drive states for the motor, in response to a corresponding high or low level provided by the polarity detection circuit and based on a converted unipolar second output DC voltage, such as +12V, from the DC buck converter circuit 23.

[0040]

[0041] As shown in Table 1, the H-bridge rectifier circuit 210 provides the ±12V power required to drive the motor of the electronic lock, with the input being the +12V output of the DC-DC step-down converter circuit 23. The motor's state can be automatically switched via power supply. When the motor needs to reverse, a +48V power supply is provided, at which point the enable pins IN1, IN2, and EN1 of the H-bridge rectifier circuit 210 are low, and EN2 is high. In other words, the H-bridge rectifier circuit 210 provides the -12V level required for motor reversal. When the motor needs to reverse, a -48V power supply is provided, at which point the enable pins IN1, IN2, and EN1 of the H-bridge rectifier circuit 210 are high, and EN2 is low. In other words, the H-bridge rectifier circuit 210 provides the +12V level required for motor reversal.

[0042] With this setup, for example specifically based on the truth table for motor control of the H-bridge rectifier circuit 210, by providing higher DC voltage inputs of different polarities, the corresponding logic pins 227 of the unipolar detection circuit 220 are provided to the H-bridge rectifier circuit 210, thereby driving the motor to achieve the desired forward or reverse rotation state, or other operating states.

[0043] In alternative exemplary embodiments of this disclosure, for example, the bridge rectifier circuit 10 includes two parallel half-bridge rectifier circuits, each half-bridge rectifier circuit being connected to the corresponding polarity of the bipolar input DC.

[0044] In another alternative exemplary embodiment of this disclosure, for example, the polarity switching circuit 22 includes a pair of high-side switches, the bridge rectifier circuit 10 being connected to the motor via the connected high-side switches, and driving the motor to switch between forward and reverse rotation, for example, in response to a synchronous control signal of the polarity of the input DC following the corresponding polarity of the high-side switch.

[0045] The improved drive device 1 for driving the motor of the electronic lock of the charging gun of a new energy vehicle, based on the above-described configuration, can achieve the following superior technical effects compared to existing technical solutions in the field:

[0046] This is achieved, for example, by designing an adapter circuit for driving the motor to adapt a 12V DC-powered motor to a 48V power supply. This improvement in circuit design eliminates the need to modify the electronic lock itself; the compatibility issue between the 48V DC power supply and the 12V DC-powered motor can be resolved solely through the design of the external connection circuit. Furthermore, regardless of whether +48V is provided at VBAT+ or -48V at VBAT-, a unipolar voltage, such as +48V, can only be obtained at the bridge input 101 of the bridge rectifier circuit 10. Simultaneously, different logic signals can be provided to the discrete unipolar detection circuit 220 of the polarity switching circuit 22, which are then transmitted to the enable pins IN1 and IN2 of the H-bridge rectifier circuit 210, which acts as the motor driver 21, to switch the motor drive state based on a truth table.

[0047] The above description of the drive device for driving the motor of the electronic lock in the foregoing embodiments of this disclosure is intended to be illustrative and not restrictive. Although this disclosure has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to exemplify preferred embodiments of this disclosure and should not be construed as limiting this disclosure.

[0048] Therefore, those skilled in the art will understand that the embodiments described above are exemplary and can be improved by those skilled in the art. The structures described in the various embodiments can be modified and freely combined without conflict in structure or principle, and these changes should fall within the protection scope of this disclosure.

[0049] The breadth and scope of this disclosure should not be limited to any of the embodiments described above, but should be defined only by the following claims and their equivalents.

[0050] It should be noted that the word "comprising" does not exclude other elements or steps, and the words "a" or "an" do not exclude multiple. Furthermore, any element reference numerals in the claims should not be construed as limiting the scope of this disclosure.

Claims

1. A drive device (1) for driving a motor of an electronic lock, characterized in that, The driving device (1) includes: A bridge rectifier circuit (10) includes at least one pair of switching device bridge arms (110) electrically connected in a bridge arrangement. The switching device bridge arms (110) are connected at the input side to two bridge input terminals (101) of the bridge rectifier circuit, each connected to a battery voltage of different polarities, and at the output side to a bridge output terminal (102) of the bridge rectifier circuit. The drive circuit (20), electrically connected upstream to the bridge rectifier circuit and downstream to the motor, includes: Motor drive device (21); and The polarity switching circuit (22) includes a switching device (221), and the switching device is connected on the input side to two second input terminals (222) respectively connected to a second voltage of different polarities, and on the output side to the motor driving device.

2. The driving device (1) according to claim 1, characterized in that, The bridge rectifier circuit (10) includes a full-bridge rectifier circuit (11), which includes two pairs of bridge arms (110) connected in parallel. Each pair of bridge arms (110) includes a front bridge arm (111) and a rear bridge arm (112) connected in series. Each bridge arm (110) has a corresponding diode (113). The bridge input terminal (101) is electrically connected at the intermediate node between the front bridge arm (111) and the rear bridge arm (112) of each pair of bridge arms (110) connected in series, and is electrically connected to the bridge output terminal (102) at the parallel connection of the respective rear bridge arms (112) of the two pairs of bridge arms (110).

3. The driving device (1) according to claim 1, characterized in that, The driving device (1) further includes a DC buck converter circuit (23), which is electrically connected between the bridge rectifier circuit (10) and the driving circuit (20). The voltage input pin (VIN) of the DC buck converter circuit (23) is connected to the bridge output terminal (102), and the voltage output pin (BIAS) of the DC buck converter circuit (23) is connected to the power supply pin (200) of the driving circuit (20).

4. The driving device (1) according to claim 3, characterized in that, The DC buck converter circuit (23) is a synchronous buck DC converter IC with integrated MOSFET.

5. The driving device (1) according to claim 3, characterized in that, The polarity switching circuit (22) includes two discrete unipolar detection circuits (220), each unipolar detection circuit (220) including a MOS switch (223) and a resistor network electrically connected to each other, and The corresponding MOS switch (223) of each unipolar detection circuit (220) is electrically connected to the corresponding bridge input (101) of the bridge rectifier circuit (10) with its gate (224), electrically connected to the voltage output pin (BIAS) of the DC buck converter circuit (23) with its source (225), and grounded with its drain (226).

6. The driving device (1) according to claim 3, characterized in that, The motor drive device (21) includes an H-bridge rectifier circuit, and the H-bridge rectifier circuit (210) is connected to the output terminal of the DC buck converter circuit (23) via the power supply pin (200) and is electrically connected to the motor via the output pin.

7. The driving device (1) according to claim 6, characterized in that, The H-bridge rectifier circuit is an H-bridge motor driver IC and includes four N-channel power MOSFETs and an internal charge pump configured to generate gate (224) drive voltage.

8. The driving device (1) according to claim 7, characterized in that, Each unipolar detection circuit (220) also has a logic pin (227) connected to the source (225) of the corresponding MOS switch (223); and The H-bridge rectifier circuit (210) is electrically connected at each of the two enable pins (IN1, IN2) to the corresponding logic pin (227) of each unipolar detection circuit (220).

9. The driving device (1) according to claim 1, characterized in that, The bridge rectifier circuit (10) includes two parallel half-bridge rectifier circuits, each of which is connected to the corresponding polarity of the bipolar input DC.

10. The driving device (1) according to claim 2 or 9, characterized in that, The polarity switching circuit (22) includes a pair of high-side switches, and the bridge rectifier circuit (10) is connected to the motor via the connected high-side switches.

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