Electrostatic motor drive circuit

Abstract

To achieve high output without increasing a size of a circuit configuration.SOLUTION: A voltage application circuit 3 includes: a half-bridge circuit 12 including switching elements Q1 and Q2; an inductor L1 having one terminal connected to the half-bridge circuit 12 and the other terminal connected to a stator electrode 5; a half-bridge circuit 13 including switching elements Q3 and Q4; and an inductor L2 having one terminal connected to the half-bridge circuit 13 and the other terminal connected to the stator electrode 5. The voltage application circuit 3 utilizes resonance between each of the inductors L1 and L2, which is generated by complementarily turning on and off the switching elements Q1, Q2 and Q3, Q4, and an electrode capacitance 6 formed with the stator electrode 5 as one electrode, to output an output voltage, which is a voltage having an amplitude higher than that of a power supply voltage VDD, from the other terminal of each of the inductors L1 and L2, and uses the output voltage to generate a positive fixed voltage, a negative fixed voltage, an A-phase voltage, and a B-phase voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrostatic motor drive circuit for driving an electrostatic motor. [Background technology]

[0002] An electrostatic motor is configured to obtain a rotational force by an electrostatic force generated between a rotor electrode, which is an electrode provided on a rotor, and a stator electrode, which is an electrode provided on a stator. An electrostatic motor drive circuit for driving such an electrostatic motor applies a fixed voltage to one of the electrodes, and applies an A-phase voltage whose level is switched depending on the rotational position and a B-phase voltage whose phase is opposite to the A-phase voltage, to the other of the electrodes. Patent Document 1 discloses an electrostatic motor drive circuit that employs a circuit configuration of an isolated flyback converter. In the following description, the configuration disclosed in Patent Document 1 will be referred to as the prior art. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-48557 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, the output voltage of the drive circuit, that is, the motor applied voltage, which is the voltage applied to the electrostatic motor, is only positive, so a correspondingly high voltage is required to achieve high output. In addition, in the conventional technology, when such a high voltage is applied, the voltage to ground becomes high, which makes the insulation design difficult and may lead to an increase in the size of the circuit configuration.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrostatic motor drive circuit that can achieve high output without increasing the size of the circuit configuration. [Means for solving the problem]

[0006] The electrostatic motor drive circuit described in claim 1 drives an electrostatic motor (2) configured to obtain a rotational force by an electrostatic force generated between an electrode (4) provided on a rotor and an electrode (5) provided on a stator, and includes a voltage application circuit (3, 41). In this case, one of the electrodes provided on the rotor and the stator is designated as a first electrode and the other is designated as a second electrode, and a voltage on the high potential side of a ground (10) that is a reference potential of the circuit is designated as a positive voltage and a voltage on the low potential side is designated as a negative voltage. The voltage application circuit applies a positive fixed voltage and a negative fixed voltage to the first electrode, and applies a first phase voltage, the positive and negative of which are switched according to the rotational position of the electrostatic motor, and a second phase voltage, the phase of which is opposite to that of the first phase voltage, to the second electrode.

[0007] The voltage application circuit includes a first half-bridge circuit (12, 21, 31) including two switching elements (Q1, Q2, Q21, Q22, Q31, Q32) connected in series between a power supply line (9) to which a power supply voltage is applied and the ground, a first inductor (L1) having one terminal connected to the first half-bridge circuit and the other terminal connected to the second electrode, a second half-bridge circuit (13) including two switching elements (Q3, Q4) connected in series between the power supply line and the ground, and a second inductor (L2) having one terminal connected to the second half-bridge circuit and the other terminal connected to the second electrode.

[0008] The voltage application circuit utilizes resonance between the first inductor and the second inductor, which occurs by complementarily turning on and off the two switching elements, and an electrode capacitance (6) formed with the second electrode as one electrode, to output an output voltage having an amplitude higher than the power supply voltage from each of the other terminals of the first inductor and the second inductor. The voltage application circuit generates the positive fixed voltage, the negative fixed voltage, the first phase voltage, and the second phase voltage using the output voltage.

[0009] According to the above configuration, the electrode capacitance specific to the electrostatic motor is utilized, and an output voltage having a higher amplitude than the power supply voltage is generated by LC resonance between the electrode capacitance and the first and second inductors, and the output voltage is used to generate a positive fixed voltage, a negative fixed voltage, a first phase voltage, and a second phase voltage. In this way, it becomes possible to apply positive and negative voltages to each electrode of the electrostatic motor, so that it is possible to increase the motor application voltage, and as a result, it is possible to improve the torque that increases in proportion to the square of the voltage, in other words, to achieve high output. In addition, this makes it easier to ensure the withstand voltage to ground, so that the circuit configuration can be made smaller. Therefore, according to the above configuration, it is possible to obtain the excellent effect of realizing high output without incurring an increase in the size of the circuit configuration. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an electrostatic motor drive circuit according to a first embodiment; [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of each electrode of the electrostatic motor according to the first embodiment; [Diagram 3] FIG. 1 is a diagram showing an example of a specific electrode configuration of an electrostatic motor according to the first embodiment. [Figure 4] FIG. 2 shows an example of a specific electrode configuration of the electrostatic motor according to the first embodiment. [Diagram 5] FIG. 4 is a diagram showing a schematic diagram of waveforms of voltages applied to each electrode of an electrostatic motor by a voltage application circuit according to the first embodiment; [Figure 6] FIG. 1 is a diagram showing the configuration of only one phase of a voltage application circuit according to a first embodiment; [Figure 7] FIG. 1 is a diagram for explaining the operation of a voltage application circuit according to a first embodiment of the present invention, which is configured for one phase; [Figure 8] FIG. 10 is a diagram showing waveforms of each part of one phase of a voltage application circuit during start-up boosting according to the first embodiment; [Figure 9]FIG. 10 is a diagram showing a schematic diagram of waveforms at each part of one phase of a voltage application circuit during actual operation according to the first embodiment; [Figure 10] FIG. 1 is a diagram showing a schematic diagram of waveforms at various parts of the entire voltage application circuit during actual operation according to the first embodiment; [Figure 11] FIG. 13 is a diagram showing the configuration of only one phase of a voltage application circuit according to a second embodiment. [Figure 12] FIG. 13 is a diagram showing the configuration of only one phase of a voltage application circuit according to a third embodiment. [Figure 13] FIG. 1 is a diagram showing the configuration of only one phase of the voltage application circuit according to the fourth embodiment. [Figure 14] FIG. 2 shows the configuration of only one phase of the voltage application circuit according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a number of embodiments will be described with reference to the drawings. Note that the same reference numerals are used to designate substantially the same components in the respective embodiments, and the description thereof will be omitted. (First embodiment) The first embodiment will be described below with reference to FIGS.

[0012] <Overall composition> As shown in FIG. 1, the electrostatic motor drive circuit 1 of this embodiment drives an electrostatic motor 2 and includes a voltage application circuit 3. In the following description, the electrostatic motor drive circuit 1 may be abbreviated as drive circuit 1. As shown in FIG. 2, the electrostatic motor 2 is configured to obtain a rotational force by an electrostatic force generated between a rotor electrode 4, which is an electrode provided on a rotor, and a stator electrode 5, which is an electrode provided on a stator. In this configuration, an electrode capacitance 6 is formed with the stator electrode 5 as one electrode and the rotor electrode 4 as the other electrode. In the following description, the rotor electrode 4 and the stator electrode 5 may be abbreviated as electrode 4 and electrode 5, respectively.

[0013] Specific electrode configurations of the electrostatic motor 2 can be, for example, those shown in Fig. 3 and Fig. 4. In Fig. 3, a large number of electrodes 4, 5 are arranged circumferentially, i.e., parallel to the axis 7. In Fig. 4, a large number of electrodes 4, 5 are arranged radially, i.e., perpendicular to the axis 7. In this case, the rotor electrode 4, which is one of the rotor electrode 4 and the stator electrode 5, corresponds to the first electrode, and the other, the stator electrode 5, corresponds to the second electrode. In this case, the voltage on the high potential side of the ground, which is the reference potential of the circuit, is set to a positive voltage, and the voltage on the low potential side is set to a negative voltage.

[0014] The voltage application circuit 3 applies a positive fixed voltage and a negative fixed voltage to the rotor electrode 4, and also applies an A-phase voltage and a B-phase voltage, the positive and negative of which are switched according to the rotational position of the electrostatic motor 2, to the stator electrode 5. In this case, the A-phase voltage corresponds to the first phase voltage, and the B-phase voltage corresponds to the second phase voltage. The positive fixed voltage, the negative fixed voltage, the A-phase voltage, and the B-phase voltage have waveforms as shown in FIG. 5. Note that in FIG. 1 and FIG. 5, the positive fixed voltage is abbreviated as "positive", the negative fixed voltage as "negative", the A-phase voltage as "A", and the B-phase voltage as "B".

[0015] The positive fixed voltage is a voltage that is constant at a voltage value higher than 0V, which is the potential of the ground 10. The negative fixed voltage is a voltage that is constant at a voltage value lower than 0V. The A-phase voltage and the B-phase voltage are voltages that alternate between voltage values ​​higher than 0V and voltage values ​​lower than 0V. However, the B-phase voltage is a voltage of opposite phase to the A-phase voltage. In other words, the A-phase voltage and the B-phase voltage are shifted in phase from each other by a half cycle.

[0016] The voltage application circuit 3 operates by receiving a power supply voltage VDD from a DC power supply 8. A high-potential terminal of the DC power supply 8 is connected to a power supply line 9 via a resistor R1, and a low-potential terminal of the DC power supply 8 is connected to a ground 10. A capacitor C1 is connected between the power supply line 9 and the ground 10, which, together with the resistor R1, constitutes a filter circuit 11 for smoothing the power supply voltage VDD.

[0017] The voltage application circuit 3 includes half-bridge circuits 12 and 13, inductors L1 and L2, and diodes D1 to D4. The half-bridge circuit 12 corresponds to a first half-bridge circuit, and includes two switching elements Q1 and Q2 connected in series between a power supply line 9 to which a power supply voltage VDD is applied and a ground 10. The half-bridge circuit 12 includes diodes D5 and D6 that function as a reverse current prevention unit that prevents reverse flow of current flowing through the two switching elements Q1 and Q2.

[0018] The switching elements Q1 and Q2 can be configured with transistors such as MOSFETs or IGBTs. In this case, both the switching elements Q1 and Q2 are N-channel MOSFETs. The drain of the switching element Q1 is connected to the power line 9, and its source is connected to a node N1 via a diode D5 in the forward direction. The drain of the switching element Q2 is connected to the node N1 via a diode D6 in the reverse direction, and its source is connected to the ground 10.

[0019] A binary drive signal Sa output from the control circuit 14 is applied to the gate of the switching element Q1 via a buffer 15. A binary drive signal Sb output from the control circuit 14 is applied to the gate of the switching element Q2 via a buffer 16. With this configuration, the control circuit 14 controls the on / off of the switching elements Q1 and Q2. A rotation signal Sc indicating the rotation position of the electrostatic motor 2 is applied to the control circuit 14. The control circuit 14 controls the operation of the drive circuit 1 based on the rotation signal Sc so that the rotation position of the electrostatic motor 2 is a desired position.

[0020] The inductor L1 corresponds to a first inductor, one terminal of which is connected to the node N1 of the half-bridge circuit 12, and the other terminal of which is connected to the stator electrode 5. The diode D1 corresponds to a first diode, the anode of which is connected to the other terminal of the inductor L1. The cathode of the diode D1 is connected to the rotor electrode 4. The diode D2 corresponds to a second diode, the cathode of which is connected to the other terminal of the inductor L1. The anode of the diode D2 is connected to the rotor electrode 4.

[0021] The half-bridge circuit 13 corresponds to a second half-bridge circuit, and includes two switching elements Q3 and Q4 connected in series between a power supply line 9 to which a power supply voltage VDD is applied and a ground 10. The half-bridge circuit 13 includes diodes D7 and D8 that function as a reverse current prevention unit that prevents reverse current flowing through the two switching elements Q3 and Q4. The switching elements Q3 and Q4 can be configured with transistors such as MOSFETs or IGBTs. In this case, both the switching elements Q3 and Q4 are N-channel MOSFETs. The drain of the switching element Q3 is connected to the power supply line 9, and its source is connected to a node N2 via a diode D7 in the forward direction.

[0022] The drain of switching element Q4 is connected to node N2 via diode D8 in the reverse direction, and its source is connected to ground 10. A binary drive signal Sd output from control circuit 14 is applied to the gate of switching element Q3 via buffer 17. A binary drive signal Se output from control circuit 14 is applied to the gate of switching element Q4 via buffer 18. With this configuration, the on / off of switching elements Q3 and Q4 is controlled by control circuit 14.

[0023] The inductor L2 corresponds to a second inductor, and one terminal of the inductor L2 is connected to the node N2 of the half-bridge circuit 13, and the other terminal of the inductor L2 is connected to the stator electrode 5. The diode D3 corresponds to a first diode, and its anode is connected to the other terminal of the inductor L2. The cathode of the diode D3 is connected to the rotor electrode 4. The diode D4 corresponds to a second diode, and its cathode is connected to the rotor electrode 4.

[0024] The voltage application circuit 3 uses LC resonance between the inductor L1 and the electrode capacitance 6, which occurs by complementarily turning on and off two switching elements Q1 and Q2 of the half-bridge circuit 12, to output an output voltage having an amplitude higher than the power supply voltage VDD from the other terminal of the inductor L1. The voltage application circuit 3 then uses the output voltage to generate a positive fixed voltage, a negative fixed voltage, and an A-phase voltage. Specifically, the voltage application circuit 3 outputs the voltage at the cathode of the diode D1 as a positive fixed voltage, and the voltage at the anode of the diode D2 as a negative fixed voltage. The voltage application circuit 3 also outputs the output voltage output from the other terminal of the inductor L1 as an A-phase voltage.

[0025] The voltage application circuit 3 uses LC resonance between the inductor L2 and the electrode capacitance 6, which occurs by complementarily turning on and off two switching elements Q3 and Q4 of the half-bridge circuit 13, to output an output voltage having an amplitude higher than the power supply voltage VDD from the other terminal of the inductor L2. The voltage application circuit 3 then uses the output voltage to generate a positive fixed voltage, a negative fixed voltage, and a B-phase voltage. Specifically, the voltage application circuit 3 outputs the voltage at the cathode of the diode D3 as a positive fixed voltage, and the voltage at the anode of the diode D4 as a negative fixed voltage. The voltage application circuit 3 also outputs the output voltage output from the other terminal of the inductor L2 as a B-phase voltage.

[0026] Next, the operation of the voltage application circuit 3 having the above configuration will be described with reference to Fig. 6 to Fig. 10. Note that in the following [1] to [3], the operation of the half-bridge circuit 12 and the configuration corresponding to the half-bridge circuit 12, that is, the configuration for one phase, will be described as an example, but the operation of the half-bridge circuit 13 and the configuration corresponding to the half-bridge circuit 13 is similar. Also, in Fig. 6, illustration of configurations that are not related to the explanation of the operation is omitted.

[0027] [1] Overview of operation As described above, the voltage application circuit 3 utilizes the resonance between the inductor L1 and the electrode capacitance 6. During the period Ta when the switching element Q1 is on, a current flows through the inductor L1 and the electrode capacitance 6 via the path A1 shown by the dotted arrow in Fig. 6, and thus a boost operation is performed. After a half cycle of the boost operation, during the period Tb when the switching element Q2 is on, a current flows through the inductor L1 and the electrode capacitance 6 via the path A2 shown by the dotted arrow in Fig. 6, and thus a regenerative operation, that is, a voltage reversal operation, is performed.

[0028] As a result of each of these operations, the output voltage output from the other terminal of the inductor L1 becomes as shown in FIG. 7. In FIG. 7 and other figures, the output voltage is Vo and the inductor current is IL. In FIG. 7 and other figures, the high level of each of the drive signals including the drive signals Sa and Sb is a level at which the switching element is turned on, and the low level is a level at which the switching element is turned off. As shown in FIG. 7, the output voltage Vo becomes a voltage having an amplitude higher than that of the power supply voltage VDD. Specifically, in the initial operation in FIG. 7, the drive signal Sa becomes a high level, so that a boost operation is performed by resonance, and the output voltage Vo is boosted to a voltage approximately twice the power supply voltage VDD. Then, after a half cycle, the drive signal Sb becomes a high level, so that an inversion operation is performed, and the output voltage Vo becomes a negative voltage, that is, a negative voltage is generated.

[0029] In the above configuration, since resonance is utilized, it is desirable to set the ON time Ton, which is the time for turning on the switching elements Q1 and Q2, to a time equal to or longer than a half cycle of the resonance. Therefore, in this embodiment, the control circuit 14 controls the operation of the drive circuit 1 so that the ON time Ton satisfies the following formula (1). Here, the inductance value of the inductor L1 is L, and the capacitance value of the electrode capacitance 6 is C.

[0030]

number

[0031] In this embodiment, for example, when the capacitance value C of the electrode capacitance 6 is 100 pF and the inductance value L of the inductor L1 is 1H, the on-time Ton is set to 31.4 μs.

[0032] [2] Waveforms of each part during startup voltage rise (for one phase) At the time of start-up boost, that is, immediately after the drive circuit 1 is started and there is no load, the waveforms of each part of one phase are as shown in FIG. 8. In this case, each operation is repeated every half cycle, such as "boosting by resonance" → "generation of negative voltage by inversion" → "boosting by resonance", and so on, so that the output voltage Vo gradually rises due to an increase in the resonance amplitude relative to the power supply voltage VDD. As a result, a voltage sufficiently larger than the power supply voltage VDD is obtained as the output voltage. According to the above configuration, after the amplitude of the output voltage reaches a desired value, the output voltage can be set to any voltage by controlling the pulse width of the drive signals Sa and Sb, that is, the on-time of the switching elements Q1 and Q2.

[0033] [3] Waveforms of each part during actual operation (one phase) During actual operation, that is, when the drive circuit 1 is driving the electrostatic motor 2, the waveforms of each part for one phase are as shown in Fig. 9. In this case, while the output voltage increases as each operation is repeated, the output voltage decreases due to the power consumption by the electrostatic motor 2 and the change in electrostatic capacitance accompanying the movement of the electrodes, and so on, so that the output voltage eventually balances at a certain level higher than the power supply voltage VDD.

[0034] 9, the output voltage drops at a certain rate from the boost operation to the reversal operation, which is due to the power consumption by the electrostatic motor 2 and the change in capacitance caused by the movement of the electrodes. In the reversal operation, the residual voltage that has dropped in this way is reversed, so that the absolute value of the output voltage is smaller for the negative voltage than for the positive voltage.

[0035] [4] Waveforms of each part during actual operation (overall) During actual operation, that is, when the output voltage is in a balanced state, the waveforms of each part as a whole are as shown in Fig. 10. The A-phase voltage applied to the stator electrode 5 is the output voltage output from the other terminal of the inductor L1, and therefore has the same waveform as the output voltage shown in Fig. 9. The B-phase voltage applied to the stator electrode 5 is the output voltage output from the other terminal of the inductor L2, and therefore has the same waveform as the output voltage shown in Fig. 9. However, the A-phase voltage and the B-phase voltage have waveforms of opposite phases to each other. In Fig. 10, the inductor current flowing through the inductor L1 is ILA, and the inductor current flowing through the inductor L2 is ILB.

[0036] The positive fixed voltage applied to rotor electrode 4 is a DC voltage having a voltage value approximately equal to the positive peak value of the A-phase voltage and B-phase voltage, since it is the voltage at the cathodes of diodes D1 and D3, i.e., the A-phase voltage and B-phase voltage rectified by diodes D1 and D3 and smoothed by the electrode capacitance between the positive and negative rotor terminals. The negative fixed voltage applied to rotor electrode 4 is a DC voltage having a voltage value approximately equal to the negative peak value of the A-phase voltage and B-phase voltage, since it is the voltage at the anodes of diodes D2 and D4, i.e., the A-phase voltage and B-phase voltage rectified by diodes D2 and D4 and smoothed by the electrode capacitance between the positive and negative rotor terminals.

[0037] According to the present embodiment described above, the following effects can be obtained. The drive circuit 1 of this embodiment utilizes an electrode capacitance 6 specific to the electrostatic motor 2, and generates an output voltage having an amplitude higher than the power supply voltage VDD through LC resonance between the electrode capacitance 6 and inductors L1 and L2, and uses the output voltage to generate a positive fixed voltage, a negative fixed voltage, an A phase voltage, and a B voltage.

[0038] In this way, since it becomes possible to apply positive and negative voltages to the electrodes 4, 5 of the electrostatic motor 2, it becomes possible to increase the voltage applied to the motor, and as a result, it becomes possible to improve the torque that increases in proportion to the square of the voltage, in other words, to achieve high output. In addition, in this way, it becomes easier to ensure the withstand voltage to ground, and therefore the circuit configuration can be made smaller. Therefore, according to this embodiment, it is possible to obtain the excellent effect of achieving high output without increasing the size of the circuit configuration.

[0039] As described above, in the drive circuit 1 of this embodiment, the electrode capacitance 6 that is originally present in the electrostatic motor 2 is used as the configuration for resonance, so the circuit configuration can be made smaller than when a separate capacitor is provided as the configuration for resonance. Also, in this embodiment, the voltage application circuit 3 is configured with inductors L1 and L2, and the switching operation for generating the output voltage is soft switching, so that switching loss and electromagnetic interference noise are reduced, and the burden on each element including the switching elements Q1 to Q4 is reduced, so that surges, heat generation, and the like can be suppressed.

[0040] In the conventional technology, the voltage is simply boosted by a transformer, and the operation does not take into account the load characteristics, so there is a risk of loss increasing and efficiency decreasing. In contrast, in the drive circuit 1 of this embodiment, it is possible to achieve high output by boosting the voltage through resonance, and furthermore, it is possible to achieve low loss, that is, high efficiency, by performing regenerative operation. In this embodiment, transistors such as MOSFETs and IGBTs can be used as the switching elements Q1 to Q4. In this way, a configuration for resonance can be formed using general-purpose elements, so that advantages such as reduced manufacturing costs and easy procurement of parts can be obtained.

[0041] The half-bridge circuit 12 includes diodes D5 and D6, which function as a reverse current prevention unit that prevents the reverse flow of current flowing through the switching elements Q1 and Q2. The half-bridge circuit 13 includes diodes D7 and D8, which function as a reverse current prevention unit that prevents the reverse flow of current flowing through the switching elements Q3 and Q4. In this way, the resonance effect can function as a boost operation.

[0042] In the voltage application circuit 3, the on-time Ton during which each of the switching elements Q1 to Q4 is turned on can be set to a time equal to or longer than a half cycle of the resonance. In this way, it is possible to reliably obtain the boosting effect due to the resonance, and it is possible to more reliably achieve high output.

[0043] Second embodiment Hereinafter, a second embodiment in which the configuration of the half-bridge circuit is changed from that of the first embodiment will be described with reference to FIG. In addition, in FIG. 11, a configuration equivalent to a first half-bridge circuit will be described as an example, but a configuration equivalent to a second half-bridge circuit can be similarly applied.

[0044] 11, the half-bridge circuit 21 of this embodiment corresponds to a first half-bridge circuit, and includes two switching elements Q21 and Q22 connected in series between a power supply line 9 and ground 10. The switching elements Q21 and Q22 are reverse blocking IGBTs, i.e., RB-IGBTs. The collector of the switching element Q21 is connected to the power supply line 9, and the emitter of the switching element Q21 is connected to a node N1. The collector of the switching element Q22 is connected to the node N1, and the emitter of the switching element Q22 is connected to the ground 10.

[0045] A drive signal Sa is applied to the gate of switching element Q21 via buffer 15 (not shown). A drive signal Sb is applied to the gate of switching element Q22 via buffer 16 (not shown). In this case, switching elements Q21 and Q22, which are formed from reverse blocking IGBTs, function as backflow prevention units that prevent reverse flow of current through the two switching elements Q21 and Q22.

[0046] This embodiment can also provide the same effects as those of the first embodiment. Furthermore, this embodiment can omit the four diodes D5 to D7 compared to the first embodiment, and therefore the number of elements can be reduced accordingly, resulting in a further miniaturization of the circuit configuration.

[0047] Third embodiment Hereinafter, a third embodiment in which the configuration of the half-bridge circuit is changed from that of the first embodiment will be described with reference to FIG. In addition, in FIG. 12, a configuration equivalent to a first half-bridge circuit will be described as an example, but a configuration equivalent to a second half-bridge circuit can be similarly applied.

[0048] 12, the half-bridge circuit 31 of this embodiment corresponds to a first half-bridge circuit, and includes two switching elements Q31, Q32 connected in series between a power supply line 9 and ground 10. The switching elements Q31, Q32 are thyristors. The anode of the switching element Q31 is connected to the power supply line 9, and the cathode of the switching element Q31 is connected to a node N1. The anode of the switching element Q22 is connected to the node N1, and the cathode of the switching element Q22 is connected to the ground 10.

[0049] A drive signal Sa is applied to the gate of switching element Q31 via buffer 15 (not shown). A drive signal Sb is applied to the gate of switching element Q32 via buffer 16 (not shown). Generally, a thyristor has the drawback that it cannot be turned off, but in this circuit, the switching elements Q31 and Q32, which are thyristors, can be turned off by stopping the current. In this case, the switching elements Q31 and Q32, which are thyristors, themselves function as backflow prevention units that prevent the backflow of current flowing through the two switching elements Q31 and Q32.

[0050] This embodiment can also provide the same effects as the first embodiment. Furthermore, this embodiment can omit the four diodes D5 to D7 compared to the first embodiment, so the number of elements can be reduced accordingly, and as a result, the circuit configuration can be made even smaller. Furthermore, this embodiment has the advantage that control is simpler than the first embodiment in which transistors such as MOSFETs are used as the switching elements Q1 and Q2, because thyristors are used as the switching elements Q31 and Q32.

[0051] (Fourth embodiment) Hereinafter, a fourth embodiment in which the configuration and arrangement of the inductors are changed from those of the first embodiment will be described with reference to FIGS.

[0052] Note that FIG. 13 illustrates only the configuration corresponding to the half-bridge circuit 12, which corresponds to the first half-bridge circuit, from the voltage application circuit 41 of this embodiment, and FIG. 14 illustrates only the configuration corresponding to the half-bridge circuit 13, which corresponds to the second half-bridge circuit, from the voltage application circuit 41 of this embodiment.

[0053] 13, the voltage application circuit 41 of this embodiment includes an inductor L3. In this case, the inductor L1 has one terminal connected to the half-bridge circuit 12 and the other terminal connected to a node N41. The inductor L3 corresponds to a third inductor, has one terminal connected to the half-bridge circuit 12 and the other terminal connected to the node N41. The node N41 is connected to the stator electrode 5 forming the electrode capacitance 6.

[0054] Specifically, one terminal of the inductor L1 is connected, via a diode D5 in the reverse direction, to the upstream switching element Q1 of the two switching elements Q1 and Q2 included in the half-bridge circuit 12. Also, one terminal of the inductor L3 is connected, via a diode D6 in the forward direction, to the downstream switching element Q2 of the two switching elements Q1 and Q2 included in the half-bridge circuit 12.

[0055] 14, the voltage application circuit 41 of this embodiment includes an inductor L4. In this case, the inductor L2 has one terminal connected to the half-bridge circuit 13 and the other terminal connected to a node N42. The inductor L4 corresponds to a fourth inductor, has one terminal connected to the half-bridge circuit 13 and the other terminal connected to the node N42. The node N42 is connected to the stator electrode 5 that forms the electrode capacitance 6.

[0056] Specifically, one terminal of the inductor L2 is connected to the upstream switching element Q3 of the two switching elements Q3 and Q4 included in the half-bridge circuit 13 via a diode D7 in the reverse direction. Also, one terminal of the inductor L4 is connected to the downstream switching element Q4 of the two switching elements Q3 and Q4 included in the half-bridge circuit 13 via a diode D8 in the forward direction.

[0057] This embodiment can also provide the same effect as the first embodiment. Both the embodiment and the first embodiment have the following advantages. The first embodiment has an advantage that the circuit configuration can be simplified compared to the present embodiment, since it is sufficient to provide one inductor corresponding to each of the half-bridge circuits 12 and 13. In contrast, this embodiment has an advantage that it is possible to reduce recovery loss compared to the first embodiment, since it is necessary to provide two inductors corresponding to each of the half-bridge circuits 12 and 13, but the inductors L1 and L2 provided upstream of the two inductors make it difficult for steep currents accompanying recovery to flow.

[0058] (Other embodiments) The present invention is not limited to the embodiments described above and illustrated in the drawings, and can be modified, combined, or expanded in any manner without departing from the spirit and scope of the present invention. The numerical values ​​and the like shown in the above embodiments are merely examples and are not intended to be limiting.

[0059] Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, and other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0060] 1...electrostatic motor drive circuit, 2...electrostatic motor, 3...voltage application circuit, 4...rotor electrode, 5...stator electrode, 6...electrode capacitance, 9...power supply line, 10...ground, 12...half-bridge circuit, 13...half-bridge circuit, 21...half-bridge circuit, 31...half-bridge circuit, 41...voltage application circuit, D1, D3...diode, D2, D4...diode, D5, D6, D7, D8...diode, L1...inductor, L2...inductor, L3...inductor, L4...inductor, Q1, Q2...switching element, Q3, Q4...switching element, Q21, Q22...switching element, Q31, Q32...switching element.

Claims

1. An electrostatic motor drive circuit for driving an electrostatic motor (2) configured to obtain a rotational force by an electrostatic force generated between an electrode (4) provided on a rotor and an electrode (5) provided on a stator, comprising: One of the electrodes provided on the rotor and the stator is designated as a first electrode and the other is designated as a second electrode. With respect to the ground (10) that is the reference potential of the circuit, the voltage on the high potential side is designated as a positive voltage and the voltage on the low potential side is designated as a negative voltage. a voltage application circuit (3, 41) that applies a positive fixed voltage and a negative fixed voltage to the first electrode, and applies a first phase voltage, the positive and negative of which are switched according to a rotational position of the electrostatic motor, and a second phase voltage, the phase of which is opposite to that of the first phase voltage, to the second electrode; The voltage application circuit includes: a first half-bridge circuit (12, 21, 31) including two switching elements (Q1, Q2, Q21, Q22, Q31, Q32) connected in series between a power supply line (9) to which a power supply voltage is applied and the ground; a first inductor (L1) having one terminal connected to the first half-bridge circuit and the other terminal connected to the second electrode; a second half-bridge circuit (13) including two switching elements (Q3, Q4) connected in series between the power supply line and the ground; a second inductor (L2) having one terminal connected to the second half-bridge circuit and the other terminal connected to the second electrode; Equipped with an output voltage having an amplitude higher than the power supply voltage is output from the other terminal of each of the first inductor and the second inductor by utilizing resonance between the first inductor and the second inductor and an electrode capacitance (6) formed with the second electrode as one electrode, which is generated by complementarily turning on and off the two switching elements; an electrostatic motor drive circuit that uses the output voltage to generate the positive fixed voltage, the negative fixed voltage, the first phase voltage, and the second phase voltage;

2. 2. The electrostatic motor drive circuit according to claim 1, wherein the first half-bridge circuit and the second half-bridge circuit are provided with a reverse current prevention unit (D5, D6, D7, D8, Q21, Q22, Q31, Q32) that prevents a reverse flow of a current flowing through the two switching elements.

3. 3. The electrostatic motor drive circuit according to claim 1, wherein an on-time during which the two switching elements are turned on is set to a time equal to or longer than a half cycle of the resonance.

4. The voltage application circuit includes: a first diode (D1, D3) having an anode connected to the other terminal of one or both of the first inductor and the second inductor; a second diode (D2, D4) having a cathode connected to the other terminal of one or both of the first inductor and the second inductor; Equipped with A voltage at the cathode of the first diode is output as the positive fixed voltage; The voltage of the anode of the second diode is output as the negative fixed voltage; The output voltage output from the other terminal of the first inductor is output as the first phase voltage; 3. The electrostatic motor drive circuit according to claim 1, wherein the output voltage output from the other terminal of the second inductor is output as the second phase voltage.

5. The voltage application circuit (41) a third inductor (L3) having one terminal connected to the first half-bridge circuit and the other terminal connected to the second electrode; a fourth inductor (L4) having one terminal connected to the second half-bridge circuit and the other terminal connected to the second electrode; Equipped with one terminal of the first inductor is connected to an upstream switching element of the two switching elements included in the first half-bridge circuit, one terminal of the third inductor is connected to a downstream switching element of the two switching elements included in the first half-bridge circuit; one terminal of the second inductor is connected to an upstream switching element of the two switching elements included in the second half-bridge circuit, 3 . The electrostatic motor drive circuit according to claim 1 , wherein one terminal of the fourth inductor is connected to a downstream switching element of the two switching elements included in the second half-bridge circuit.

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