Motor gear shifting speed change circuit and method

Abstract

An H-bridge circuit comprises three-phase windings U, V and W. A switch element of a series control circuit is connected with the tail ends of the three-phase windings U, V and W. When the H-bridge circuit outputs alternating-current voltages with different phases to the head ends and the tail ends of the three-phase windings, the H-bridge circuit outputs alternating-current voltages with different phases to the head ends and the tail ends of the three-phase windings. When the three switching elements of the series control circuit are in an off state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a group of three-phase alternating-current voltage to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and three switch elements of the series control circuit are in a conducting state, the tail ends of the three-phase winding U, V and W are in short circuit to form a star connection mode, so that the three-phase winding is in a series working state, and the three-phase winding is connected in series. The size of the whole controller is reduced, mechanical contact switching is avoided, the switching completion time is short, and the controller can be used for frequent switching occasions.

Description

Technical Field

[0001] The present invention relates to the field of motor driving, and in particular to a motor gear shifting and speed changing circuit and method. Background Art

[0002] Brushless DC motors generally only work in one connection mode. Star connection is used for those requiring high starting torque, and delta connection is used for those requiring high speed. According to the motor static voltage balance equation Ua=Ea+IaRa, Ea represents the back electromotive force after the motor is running, which is proportional to the motor speed, and the more turns the motor winding has, the greater the Ea at the same speed. Ia represents the phase current when the motor is running, and is proportional to the motor output torque after multiplying it by the number of turns of the motor winding. Therefore, to increase the torque of the motor, in addition to increasing the winding current, the number of winding turns can also be increased. However, after increasing the number of winding turns, the greater the Ea at the same speed, the lower the maximum speed of the motor, and it is unable to output high power and high speed. Conversely, to increase the maximum speed of the motor, the number of winding turns can be reduced, but this also sacrifices the motor output torque;

[0003] In the existing technology, star-delta connection is a commonly used motor control method. Star connection is used during startup, which actually makes the motor winding work in series mode. After reaching a certain speed, it switches to delta connection, and the motor winding works in independent mode. It is used for high-power operation of the motor, but the entire switching is performed using a mechanical switch, which is large in size and cannot work frequently.

[0004] like Figure 1 The figure shows the star-delta starting control diagram in the prior art, where Ua, Ub, and Uc are three-phase alternating current, U, V, and W are three groups of motor windings, U1 and U2 are the beginning and end of the U winding, V1 and V2 are the beginning and end of the V winding, W1 and W2 are the beginning and end of the W winding, KM is the main power switch relay, KMy is a star connection control relay, and KMΔ is a delta connection control relay. When KMy is closed and KMΔ is disconnected, it is a star connection, and the tail ends of the three motor windings U2, V2, and W2 of UVW are connected in series, and the three-phase alternating current supplies power to the motor windings connected in series; when KMΔ is closed and KMy is disconnected, it is a delta connection, and the three groups of motor windings UVW are connected head to tail, which is specifically manifested as: U2 is connected to V1, V2 is connected to W1, and W2 is connected to U1, and the three-phase alternating current supplies power to each motor phase line separately. Because relays are large in size, short in life, poor in vibration resistance, easily damaged contacts, long switching times, and intermittent power, they cannot be used in places where frequent switching occurs.

[0005] Therefore, it is necessary to design a motor shift switching circuit with a small controller size, no mechanical contact switching, short switching completion time and can be used in occasions of frequent switching. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the current motor drive field, the present invention provides a motor gear shifting and speed changing circuit and method. When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase winding respectively, and the three switch elements of the series control circuit are in a disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltages to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switch elements of the series control circuit are in a conducting state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, which can achieve the effect of reducing the size of the overall controller, switching without mechanical contacts, short switching completion time and can be used in occasions of frequent switching.

[0007] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0008] A motor gear shifting and speed changing circuit, comprising three H-bridge circuits and a series control circuit connected thereto, wherein the H-bridge circuit comprises an upper bridge arm, a lower bridge arm and a crossbar, wherein the crossbars of the H-bridge circuit are respectively three-phase windings U, V and W of the motor, wherein the series control circuit comprises three switch elements whose drains are connected to each other, wherein the sources of the switch elements are respectively connected to the tail ends of the three-phase windings U, V and W, and when the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in an off state, the output of the H-bridge circuit is The output voltage is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltage to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switching elements of the series control circuit are in a conducting state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, and by controlling the switching state of the switching elements, the motor shifting speed circuit does not rely on external relays or mechanical switches for frequent switching.

[0009] According to one aspect of the present invention, the upper bridge arm includes a first switch and a second switch, the lower bridge arm includes a third switch and a fourth switch, the drains of the first switch and the second switch are connected to the positive electrode of a DC power supply, the sources of the third switch and the fourth switch are connected to the negative electrode of the DC power supply, the head end of the three-phase winding is connected to the source of the first switch and the drain of the third switch, and the tail end of the three-phase winding is connected to the source of the second switch and the drain of the fourth switch.

[0010] According to one aspect of the present invention, the first switch and the third switch output a set of three-phase AC voltages, the second switch and the fourth switch have no output, and the three switching elements of the series control circuit are in the on state, so that the tail ends of the three-phase windings U, V and W are short-circuited to each other.

[0011] According to one aspect of the present invention, the first switch, the second switch, the third switch and the fourth switch respectively output AC voltages with different phases to the head and tail of the three-phase winding, and the three switching elements of the series control circuit are in a disconnected state, so that the three-phase windings U, V and W are each in an independent working state.

[0012] According to one aspect of the present invention, the first switch, the second switch, the third switch and the fourth switch are all fully controlled power transistors.

[0013] According to one aspect of the present invention, the present invention further includes a controller for controlling the conduction states of the first switch, the second switch, the third switch and the fourth switch on the H-bridge circuit.

[0014] According to one aspect of the present invention, the controller is connected to the gates of the first switch, the second switch, the third switch and the fourth switch, and is used to control the input or shutdown of the voltage drive.

[0015] According to one aspect of the present invention, the controller controls the H-bridge circuit to output a corresponding AC voltage by adopting pulse width modulation.

[0016] According to one aspect of the present invention, the three switch elements of the series control circuit are all fully controlled power transistors.

[0017] A motor shifting method includes three H-bridge circuits and a series control circuit connected thereto, wherein the H-bridge circuit includes an upper bridge arm, a lower bridge arm and a crossbar, and the crossbars of the H-bridge circuit are respectively the three-phase windings U, V and W of the motor, and is characterized in that it includes the following steps:

[0018] Three switch elements with drains connected to each other are arranged in the series control circuit, and are used to be connected to the tail ends of the three-phase windings U, V and W;

[0019] When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state;

[0020] When the H-bridge circuit outputs a set of three-phase AC voltage to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switching elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection, so that the three-phase windings are in a series working state.

[0021] Advantages of the implementation of the present invention: the switch elements of the series control circuit are respectively connected to the tail ends of the three-phase windings U, V and W. When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltages to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switch elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, which can achieve the effect of reducing the size of the overall controller, switching without mechanical contacts, short switching completion time and can be used in occasions of frequent switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A circuit diagram of the prior art of a motor gear shifting and speed changing circuit and method according to the present invention;

[0024] Figure 2 A circuit diagram of a motor gear shifting and speed changing circuit and method according to the present invention;

[0025] Figure 3 It is a circuit diagram of a second embodiment of a motor gear shifting and speed changing circuit and method according to the present invention;

[0026] Figure 4 It is a schematic diagram of an equivalent circuit of a motor gear shifting and speed changing circuit and method according to the present invention, in which motor windings are connected in series;

[0027] Figure 5 It is a schematic diagram of an equivalent circuit of independent working connection of motor windings of a motor gear shifting and speed changing circuit and method described in the present invention;

[0028] Figure 6A schematic diagram of the gate, drain and source of a switching element of a motor gear shifting and speed changing circuit and method described in the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Embodiment 1:

[0031] like Figure 2 and Figure 6 As shown, a motor shifting and speed changing circuit includes three identical H-bridge circuits and a series control circuit, wherein the H-bridge circuit includes an upper bridge arm, a lower bridge arm and a crossbar, and the crossbars of the H-bridge circuit are respectively the three-phase windings U, V and W of the motor, and the motor shifting and speed changing circuit includes: a first H-bridge circuit 1, a second H-bridge circuit 2, a third H-bridge circuit 3 and a series control circuit 4. The first H-bridge circuit 1 includes: a switch element S11, a switch element S12, a switch element S13, a switch element S14 and a first winding U; the second H-bridge circuit 2 includes: a switch element S21, a switch element S22, a switch element S23, a switch element S24 and a second winding V; the third H-bridge circuit 3 includes: a switch element S31, a switch element S32, a switch element S33, a switch element S34 and a third winding W. Among them, S11, S12, S21, S22, S31, S32 are all upper bridge arms, and S13, S14, S23, S24, S33, S34 are all lower bridge arms. The series control circuit 4 includes: a switch element S5, a switch element S6 and a switch element S7.

[0032] The first H-bridge circuit 1 is specifically as follows: the drains of the switch element S11 and the switch element S12 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S13 and the switch element S14 are connected to the sources of the switch element S11 and the switch element S12 respectively, the sources of the switch element S13 and the switch element S14 are connected in parallel to the negative electrode GND of the DC power supply, the head end U1 of the first winding U is connected to the source of the switch element S11 and the drain of the switch element S13, and the tail end U2 of the first winding U is connected to the source of the switch element S12 and the drain of the switch element S14.

[0033] The second H-bridge circuit 2 is specifically as follows: the drains of the switch element S21 and the switch element S22 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S23 and the switch element S24 are connected to the sources of the switch element S21 and the switch element S22 respectively, the sources of the switch element S23 and the switch element S24 are connected in parallel to the negative electrode GND of the DC power supply, the head end V1 of the second winding V is connected to the source of the switch element S21 and the drain of the switch element S23, and the tail end V2 of the second winding V is connected to the source of the switch element S22 and the drain of the switch element S24.

[0034] The third H-bridge circuit 3 is specifically as follows: the drains of the switch element S31 and the switch element S32 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S33 and the switch element S34 are connected to the sources of the switch element S31 and the switch element S32 respectively, the sources of the switch element S33 and the switch element S34 are connected in parallel to the negative electrode GND of the DC power supply, the head end W1 of the third winding W is connected to the source of the switch element S31 and the drain of the switch element S33, and the tail end W2 of the third winding W is connected to the source of the switch element S32 and the drain of the switch element S34.

[0035] The series control circuit 4 is specifically as follows: the source of the switch element S5 is connected to the tail end W2 of the third winding, the source of the switch element S32 of the third H-bridge circuit 3, and the drain of the switch element S34; the source of the switch element S6 is connected to the tail end V2 of the second winding, the source of the switch element S22 of the second H-bridge circuit 2, and the drain of the switch element S24; the source of the switch element S7 is connected to the tail end U2 of the first winding, the source of the switch element S12 of the first H-bridge circuit 1, and the drain of the switch element S14; the drain of the fifth switch element S5 is connected to the drain of the sixth switch S6 and the drain of the seventh switch S7.

[0036] like Figure 2 and Figure 4 As shown, when the switching element S of the first H-bridge circuit 1 11 and the switching element S 13 Output voltage, so that the first end of winding U 1 The voltage of the second H-bridge circuit 2 is Ua; the switching element S 21 and the switching element S 23 Output voltage, so that the first end of the winding V 1 The voltage of the third H-bridge circuit 3 is Ub voltage; the switching element S 31 and the switching element S 33 Output voltage, so that the first end of winding W 1 The voltage of the first H-bridge circuit 1 is Uc; the switching element S 12 and the switching element S 14 , the switching element S of the second H-bridge circuit 2 22and the switching element S 24 and the switching element S of the third H-bridge circuit 3 32 and the switching element S 34 Turn off the output, and connect the switch element S of the series control circuit 4 5 , Switching element S 6 and the switching element S 7 When in the on state, the three winding ends U 2 、V 2 and W 2 Short circuit, the effect is as follows Figure 4 The star connection shown, the first end of the first winding U 1 , the first end of the second winding V 1 and the first end of the third winding W 1 It is equivalent to connecting the three-phase alternating current Ua, Ub, and Uc. The tail end U 2 , the tail end of the second winding V 2 and the tail end of the third winding W 2 Connect at one point.

[0037] like Figure 2 and Figure 5 As shown, when the switching element S of the first H-bridge circuit 1 11 and the switching element S 13 Output voltage, so that the first end of winding U 1 The voltage of the second H-bridge circuit 2 is Ua1; the switching element S 21 and the switching element S 23 Output voltage, so that the first end of the winding V 1 The voltage of the third H-bridge circuit 3 is Ub1; the switching element S 31 and the switching element S 33 Output voltage, so that the first end of winding W 1 The voltage of the first H-bridge circuit 1 is Uc1; the switching element S 12 and the switching element S 14 Output voltage, so that the end of winding U 2 The voltage of the second H-bridge circuit 2 is Ua2; the switching element S 22 and the switching element S 24 output voltage, so that the end of the winding V 2 The voltage of the third H-bridge circuit 3 is Ub2; the switching element S 32 and the switching element S 34 The output voltage makes the end of winding W 2 The voltage is Uc2; the switch element S of the series control circuit 4 5 , Switching element S 6 and the switching element S 7When it is in the disconnected state, it is equivalent to the tail ends of the three windings U, V and W being disconnected. The effect diagram is as follows Figure 5 In the independent connection shown, the first winding is equivalent to Ua directly connected to the alternating current, the second winding is equivalent to Ub directly connected to the alternating current, and the first winding is equivalent to Uc directly connected to the alternating current.

[0038] By controlling the switching state of the switch element, the motor gear shifting and speed changing circuit can be frequently switched without the aid of an external relay or a mechanical switch.

[0039] Among them, the switching element S 11 , Switching element S 12 , Switching element S 13 , Switching element S 14 , Switching element S 21 , Switching element S 22 , Switching element S 23 , Switching element S 24 , Switching element S 31 , Switching element S 32 , Switching element S 33 , Switching element S 34 , Switching element S 5 , Switching element S 6 and the switching element S 7 It is a fully controlled power transistor. Semiconductor switches such as insulated gate bipolar transistor (IGBT) or metal-oxide-semiconductor field-effect transistor (MOSFET) belong to the fully controlled power transistor. Generally, MOS is used for low voltage and IGBT is used for high voltage. MOS includes N-channel MOS and P-channel MOS. In this embodiment, N-channel MOS is used. If it is P-channel MOS, the position of source S or drain D will be changed.

[0040] Wherein, the switch element S 5 , Switching element S 6 and the switching element S 7 Responsible for controlling the short-circuit and disconnection of the tails of the three windings U, V and W.

[0041] The windings U, V and W are three sets of windings of the motor, and the three sets of windings are respectively connected to three H-bridge circuits to separately control the voltages at the head and tail ends thereof.

[0042] The H-bridge circuit further includes a controller for controlling the conduction state of the switch element on the H-bridge circuit. The controller is connected to the gate G of the switch element. The controller controls the input or shutdown of the voltage drive. The controller of this embodiment uses pulse width modulation (PWM) to control the three H-bridges to output corresponding AC voltages.

[0043] Advantages of the implementation of the present invention: the switch elements of the series control circuit are respectively connected to the tail ends of the three-phase windings U, V and W. When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltages to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switch elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, which can achieve the effect of reducing the size of the overall controller, switching without mechanical contacts, short switching completion time and can be used in occasions of frequent switching.

[0044] Embodiment 2:

[0045] like Figure 3 and Figure 6 As shown, a motor shifting and speed changing circuit includes three identical H-bridge circuits and a series control circuit, wherein the H-bridge circuit includes an upper bridge arm, a lower bridge arm and a crossbar, and the crossbars of the H-bridge circuit are respectively the three-phase windings U, V and W of the motor, and the motor shifting and speed changing circuit includes: a first H-bridge circuit 1, a second H-bridge circuit 2, a third H-bridge circuit 3 and a series control circuit 4. The first H-bridge circuit 1 includes: a switch element S11, a switch element S12, a switch element S13, a switch element S14 and a first winding U; the second H-bridge circuit 2 includes: a switch element S21, a switch element S22, a switch element S23, a switch element S24 and a second winding V; the third H-bridge circuit 3 includes: a switch element S31, a switch element S32, a switch element S33, a switch element S34 and a third winding W. Among them, S11, S12, S21, S22, S31, S32 are all upper bridge arms, and S13, S14, S23, S24, S33, S34 are all lower bridge arms. The series control circuit 4 includes: a switch element S5, a switch element S6 and a switch element S7.

[0046] The first H-bridge circuit 1 is specifically as follows: the drains of the switch element S11 and the switch element S12 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S13 and the switch element S14 are connected to the sources of the switch element S11 and the switch element S12 respectively, the sources of the switch element S13 and the switch element S14 are connected in parallel to the negative electrode GND of the DC power supply, the head end U1 of the first winding U is connected to the source of the switch element S11 and the drain of the switch element S13, and the tail end U2 of the first winding U is connected to the source of the switch element S12 and the drain of the switch element S14.

[0047] The second H-bridge circuit 2 is specifically as follows: the drains of the switch element S21 and the switch element S22 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S23 and the switch element S24 are connected to the sources of the switch element S21 and the switch element S22 respectively, the sources of the switch element S23 and the switch element S24 are connected in parallel to the negative electrode GND of the DC power supply, the head end V1 of the second winding V is connected to the source of the switch element S21 and the drain of the switch element S23, and the tail end V2 of the second winding V is connected to the source of the switch element S22 and the drain of the switch element S24.

[0048] The third H-bridge circuit 3 is specifically as follows: the drains of the switch element S31 and the switch element S32 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S33 and the switch element S34 are connected to the sources of the switch element S31 and the switch element S32 respectively, the sources of the switch element S33 and the switch element S34 are connected in parallel to the negative electrode GND of the DC power supply, the head end W1 of the third winding W is connected to the source of the switch element S31 and the drain of the switch element S33, and the tail end W2 of the third winding W is connected to the source of the switch element S32 and the drain of the switch element S34.

[0049] The series control circuit 4 is specifically as follows: the drain of the switching element S5 is connected to the tail end W2 of the third winding, the source of the switching element S32 of the third H-bridge circuit 3 and the drain of the switching element S34; the drain of the switching element S6 is connected to the tail end V2 of the second winding, the source of the switching element S22 of the second H-bridge circuit 2 and the drain of the switching element S24; the drain of the switching element S7 is connected to the tail end U2 of the first winding, the source of the switching element S12 of the first H-bridge circuit 1 and the drain of the switching element S14; the source of the fifth switching element S5 is connected to the source of the sixth switch S6 and the source of the seventh switch S7.

[0050] like Figure 3 and Figure 4 As shown, when the switching element S of the first H-bridge circuit 1 11 and the switching element S 13 Output voltage, so that the first end of winding U 1 The voltage of the second H-bridge circuit 2 is Ua; the switching element S21 and the switching element S 23 Output voltage, so that the first end of the winding V 1 The voltage of the third H-bridge circuit 3 is Ub voltage; the switching element S 31 and the switching element S 33 Output voltage, so that the first end of winding W 1 The voltage of the first H-bridge circuit 1 is Uc; the switching element S 12 and the switching element S 14 , the switching element S of the second H-bridge circuit 2 22 and the switching element S 24 and the switching element S of the third H-bridge circuit 3 32 and the switching element S 34 Turn off the output, and connect the switch element S of the series control circuit 4 5 , Switching element S 6 and the switching element S 7 When in the on state, the three winding ends U 2 、V 2 and W 2 Short circuit, the effect is as follows Figure 4 The star connection shown, the first end of the first winding U 1 , the first end of the second winding V 1 and the first end of the third winding W 1 It is equivalent to connecting the three-phase alternating current Ua, Ub, and Uc. The tail end U 2 , the tail end of the second winding V 2 and the tail end of the third winding W 2 Connect at one point.

[0051] like Figure 3 and Figure 5 As shown, when the switching element S of the first H-bridge circuit 1 11 and the switching element S 13 Output voltage, so that the first end of winding U 1 The voltage of the second H-bridge circuit 2 is Ua1; the switching element S 21 and the switching element S 23 Output voltage, so that the first end of the winding V 1 The voltage of the third H-bridge circuit 3 is Ub1; the switching element S 31 and the switching element S 33 Output voltage, so that the first end of winding W 1 The voltage of the first H-bridge circuit 1 is Uc1; the switching element S 12 and the switching element S 14 Output voltage, so that the end of winding U 2 The voltage of the second H-bridge circuit 2 is Ua2; the switching element S 22and the switching element S 24 output voltage, so that the end of the winding V 2 The voltage of the third H-bridge circuit 3 is Ub2; the switching element S 32 and the switching element S 34 The output voltage makes the end of winding W 2 The voltage is Uc2; the switch element S of the series control circuit 4 5 , Switching element S 6 and the switching element S 7 When it is in the disconnected state, it is equivalent to the tail ends of the three windings U, V and W being disconnected. The effect diagram is as follows Figure 5 In the independent connection shown, the first winding is equivalent to Ua directly connected to the alternating current, the second winding is equivalent to Ub directly connected to the alternating current, and the first winding is equivalent to Uc directly connected to the alternating current.

[0052] By controlling the switching state of the switch element, the motor gear shifting and speed changing circuit can be frequently switched without the aid of an external relay or a mechanical switch.

[0053] Among them, the switching element S 11 , Switching element S 12 , Switching element S 13 , Switching element S 14 , Switching element S 21 , Switching element S 22 , Switching element S 23 , Switching element S 24 , Switching element S 31 , Switching element S 32 , Switching element S 33 , Switching element S 34 , Switching element S 5 , Switching element S 6 and the switching element S 7 It is a fully controlled power transistor, an insulated gate bipolar transistor

[0054] Semiconductor switches such as Insulated Gate Bipolar Transistor (IGBT) or Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) are fully controlled power transistors. Generally, MOS is used for low voltage and IGBT is used for high voltage. MOS includes N-channel MOS and P-channel MOS. In this embodiment, N-channel MOS is used. If it is P-channel MOS, the position of source S or drain D will be changed.

[0055] Wherein, the switch element S 5 , Switching element S6 and the switching element S 7 Responsible for controlling the short-circuit and disconnection of the tails of the three windings U, V and W.

[0056] The windings U, V and W are three sets of windings of the motor, and the three sets of windings are respectively connected to three H-bridge circuits to separately control the voltages at the head and tail ends thereof.

[0057] The H-bridge circuit further includes a controller for controlling the conduction state of the switch element on the H-bridge circuit. The controller is connected to the gate G of the switch element. The controller controls the input or shutdown of the voltage drive. The controller of this embodiment uses pulse width modulation (PWM) to control the three H-bridges to output corresponding AC voltages.

[0058] Advantages of the implementation of the present invention: the switch elements of the series control circuit are respectively connected to the tail ends of the three-phase windings U, V and W. When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltages to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switch elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, which can achieve the effect of reducing the size of the overall controller, switching without mechanical contacts, short switching completion time and can be used in occasions of frequent switching.

[0059] Embodiment three:

[0060] A motor shifting and speed changing method is implemented based on a motor shifting and speed changing circuit described in Example 1, comprising three H-bridge circuits and a series control circuit connected thereto, wherein the H-bridge circuit comprises an upper bridge arm, a lower bridge arm and a crossbar, and the crossbars of the H-bridge circuit are respectively the three-phase windings U, V and W of the motor. The following steps are also included:

[0061] S1: three switch elements with drains connected to each other are arranged in the series control circuit, and are used to be connected to the tail ends of the three-phase windings U, V and W.

[0062] It also includes: a first H-bridge circuit 1, a second H-bridge circuit 2, a third H-bridge circuit 3 and a series control circuit 4. The first H-bridge circuit 1 includes: switch element S11, switch element S12, switch element S13, switch element S14 and a first winding U; the second H-bridge circuit 2 includes: switch element S21, switch element S22, switch element S23, switch element S24 and a second winding V; the third H-bridge circuit 3 includes: switch element S31, switch element S32, switch element S33, switch element S34 and a third winding W. Among them, S11, S12, S21, S22, S31, S32 are all upper bridge arms, and S13, S14, S23, S24, S33, S34 are all lower bridge arms. The series control circuit 4 includes: switch element S5, switch element S6 and switch element S7.

[0063] The first H-bridge circuit 1 is specifically as follows: the drains of the switch element S11 and the switch element S12 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S13 and the switch element S14 are connected to the sources of the switch element S11 and the switch element S12 respectively, the sources of the switch element S13 and the switch element S14 are connected in parallel to the negative electrode GND of the DC power supply, the head end U1 of the first winding U is connected to the source of the switch element S11 and the drain of the switch element S13, and the tail end U2 of the first winding U is connected to the source of the switch element S12 and the drain of the switch element S14.

[0064] The second H-bridge circuit 2 is specifically as follows: the drains of the switch element S21 and the switch element S22 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S23 and the switch element S24 are connected to the sources of the switch element S21 and the switch element S22 respectively, the sources of the switch element S23 and the switch element S24 are connected in parallel to the negative electrode GND of the DC power supply, the head end V1 of the second winding V is connected to the source of the switch element S21 and the drain of the switch element S23, and the tail end V2 of the second winding V is connected to the source of the switch element S22 and the drain of the switch element S24.

[0065] The third H-bridge circuit 3 is specifically as follows: the drains of the switch element S31 and the switch element S32 are connected in parallel to the positive electrode Vcc of the DC power supply, the drains of the switch element S33 and the switch element S34 are connected to the sources of the switch element S31 and the switch element S32 respectively, the sources of the switch element S33 and the switch element S34 are connected in parallel to the negative electrode GND of the DC power supply, the head end W1 of the third winding W is connected to the source of the switch element S31 and the drain of the switch element S33, and the tail end W2 of the third winding W is connected to the source of the switch element S32 and the drain of the switch element S34.

[0066] The series control circuit 4 is specifically as follows: the source of the switch element S5 is connected to the tail end W2 of the third winding, the source of the switch element S32 of the third H-bridge circuit 3, and the drain of the switch element S34; the source of the switch element S6 is connected to the tail end V2 of the second winding, the source of the switch element S22 of the second H-bridge circuit 2, and the drain of the switch element S24; the source of the switch element S7 is connected to the tail end U2 of the first winding, the source of the switch element S12 of the first H-bridge circuit 1, and the drain of the switch element S14; the drain of the fifth switch element S5 is connected to the drain of the sixth switch S6 and the drain of the seventh switch S7.

[0067] S2: When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switching elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state.

[0068] like Figure 2 and Figure 5 As shown, when the switching element S of the first H-bridge circuit 1 11 and the switching element S 13 Output voltage, so that the first end of winding U 1 The voltage of the second H-bridge circuit 2 is Ua1; the switching element S 21 and the switching element S 23 Output voltage, so that the first end of the winding V 1 The voltage of the third H-bridge circuit 3 is Ub1; the switching element S 31 and the switching element S 33 Output voltage, so that the first end of winding W 1 The voltage of the first H-bridge circuit 1 is Uc1; the switching element S 12 and the switching element S 14 Output voltage, so that the end of winding U 2 The voltage of the second H-bridge circuit 2 is Ua2; the switching element S 22 and the switching element S 24 output voltage, so that the end of the winding V 2 The voltage of the third H-bridge circuit 3 is Ub2; the switching element S 32 and the switching element S 34 The output voltage makes the end of winding W 2 The voltage is Uc2; the switch element S of the series control circuit 4 5 , Switching element S 6 and the switching element S 7 When it is in the disconnected state, it is equivalent to the tail ends of the three windings U, V and W being disconnected. The effect diagram is as follows Figure 5In the independent connection shown, the first winding is equivalent to Ua directly connected to the alternating current, the second winding is equivalent to Ub directly connected to the alternating current, and the first winding is equivalent to Uc directly connected to the alternating current.

[0069] S3: When the H-bridge circuit outputs a set of three-phase AC voltage to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switching elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection, so that the three-phase windings are in a series working state.

[0070] like Figure 2 and Figure 4 As shown, when the switching element S of the first H-bridge circuit 1 11 and the switching element S 13 Output voltage, so that the first end of winding U 1 The voltage of the second H-bridge circuit 2 is Ua; the switching element S 21 and the switching element S 23 Output voltage, so that the first end of the winding V 1 The voltage of the third H-bridge circuit 3 is Ub voltage; the switching element S 31 and the switching element S 33 Output voltage, so that the first end of winding W 1 The voltage of the first H-bridge circuit 1 is Uc; the switching element S 12 and the switching element S 14 , the switching element S of the second H-bridge circuit 2 22 and the switching element S 24 and the switching element S of the third H-bridge circuit 3 32 and the switching element S 34 Turn off the output, and connect the switch element S of the series control circuit 4 5 , Switching element S 6 and the switching element S 7 When in the on state, the three winding ends U 2 、V 2 and W 2 Short circuit, the effect is as follows Figure 4 The star connection shown, the first end of the first winding U 1 , the first end of the second winding V 1 and the first end of the third winding W 1 It is equivalent to connecting the three-phase alternating current Ua, Ub, and Uc. The tail end U 2 , the tail end of the second winding V 2 and the tail end of the third winding W 2 Connect at one point.

[0071] By controlling the switching state of the switch element, the motor gear shifting and speed changing circuit can be frequently switched without the aid of an external relay or a mechanical switch.

[0072] Among them, switch element S11, switch element S12, switch element S13, switch element S14, switch element S21, switch element S22, switch element S23, switch element S24, switch element S31, switch element S32, switch element S33, switch element S34, switch element S5, switch element S6 and switch element S7 are fully controlled power transistors, and semiconductor switches such as insulated gate bipolar transistor (IGBT) or metal-oxide-semiconductor field-effect transistor (MOSFET) belong to fully controlled power transistors. Generally, MOS is used for low voltage and IGBT is used for high voltage. MOS includes N-channel MOS and P-channel MOS. In this embodiment, N-channel MOS is used. If it is P-channel MOS, the position of source S or drain D will be changed.

[0073] The switch element S5 , the switch element S6 and the switch element S7 are responsible for controlling the tails of the three windings U, V and W to be short-circuited and disconnected.

[0074] The windings U, V and W are three sets of windings of the motor, and the three sets of windings are respectively connected to three H-bridge circuits to separately control the voltages at the head and tail ends thereof.

[0075] The H-bridge circuit further includes a controller for controlling the conduction state of the switch element on the H-bridge circuit. The controller is connected to the gate G of the switch element. The controller controls the input or shutdown of the voltage drive. The controller of this embodiment uses pulse width modulation (PWM) to control the three H-bridges to output corresponding AC voltages.

[0076] Advantages of the implementation of the present invention: the switch elements of the series control circuit are respectively connected to the tail ends of the three-phase windings U, V and W. When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltages to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switch elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, which can achieve the effect of reducing the size of the overall controller, switching without mechanical contacts, short switching completion time and can be used in occasions of frequent switching.

[0077] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A motor shifting speed changing circuit, comprising three H-bridge circuits and a series control circuit connected thereto, wherein the H-bridge circuit comprises an upper bridge arm, a lower bridge arm and a crossbar, and the crossbars of the H-bridge circuit are respectively the three-phase windings U, V and W of the motor, characterized in that: The series control circuit includes three switch elements whose drains are connected to each other, and the sources of the switch elements are connected to the tail ends of the three-phase windings U, V and W respectively. When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in a disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; when the H-bridge circuit outputs a set of three-phase AC voltages to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switch elements of the series control circuit are in a conducting state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection mode, so that the three-phase windings are in a series working state, and by controlling the switching state of the switch elements, the motor gear shifting and speed changing circuit does not rely on external relays or mechanical switches for frequent switching.

2. The motor shifting speed changing circuit according to claim 1, characterized in that: The upper bridge arm includes a first switch and a second switch, and the lower bridge arm includes a third switch and a fourth switch, the drains of the first switch and the second switch are connected to the positive electrode of the DC power supply, the sources of the third switch and the fourth switch are connected to the negative electrode of the DC power supply, the head end of the three-phase winding is connected to the source of the first switch and the drain of the third switch, and the tail end of the three-phase winding is connected to the source of the second switch and the drain of the fourth switch.

3. The motor shifting speed changing circuit according to claim 2, characterized in that: The first switch and the third switch output a set of three-phase AC voltages, the second switch and the fourth switch have no output, and the three switch elements of the series control circuit are in a conducting state, so that the tail ends of the three-phase windings U, V and W are short-circuited with each other.

4. The motor shifting speed changing circuit according to claim 2, characterized in that: The first switch, the second switch, the third switch and the fourth switch respectively output AC voltages with different phases to the head and tail of the three-phase winding, and the three switch elements of the series control circuit are in a disconnected state, so that the three-phase windings U, V and W are each in an independent working state.

5. The motor shifting and speed changing circuit according to claim 2, characterized in that: The first switch, the second switch, the third switch and the fourth switch are all fully controlled power transistors.

6. The motor shifting and speed changing circuit according to claim 2, characterized in that: The invention also includes a controller for controlling the conduction states of the first switch, the second switch, the third switch and the fourth switch on the H-bridge circuit.

7. The motor shifting and speed changing circuit according to claim 6, characterized in that: The controller is connected to the gates of the first switch, the second switch, the third switch and the fourth switch, and is used to control the input or shutdown of voltage driving.

8. The motor shifting speed changing circuit according to claim 7, characterized in that: The controller controls the H-bridge circuit to output a corresponding AC voltage by adopting pulse width modulation.

9. The motor shifting speed changing circuit according to any one of claims 1 to 8, characterized in that: The three switch elements of the series control circuit are all fully controlled power transistors.

10. A motor shifting and speed changing method, implemented based on a motor shifting and speed changing circuit according to claim 1, comprising three H-bridge circuits and a series control circuit connected thereto, wherein the H-bridge circuit comprises an upper bridge arm, a lower bridge arm and a crossbar, and the crossbars of the H-bridge circuit are respectively the three-phase windings U, V and W of the motor, characterized in that: The following steps are involved: Three switch elements with drains connected to each other are arranged in the series control circuit, and are used to be connected to the tail ends of the three-phase windings U, V and W; When the H-bridge circuit outputs AC voltages with different phases to the head and tail ends of the three-phase windings respectively, and the three switch elements of the series control circuit are in the disconnected state, the output voltage of the H-bridge circuit is directly loaded to the three-phase windings U, V and W, so that the three-phase windings are in an independent working state; When the H-bridge circuit outputs a set of three-phase AC voltage to the head end of the three-phase winding and does not output voltage to the tail end of the three-phase winding, and the three switching elements of the series control circuit are in the on state, the tail ends of the three-phase windings U, V and W are short-circuited to each other to form a star connection, so that the three-phase windings are in a series working state.

Images