WO1998012799A1 - Electrostatic actuator and helping device utilizing it - Google Patents

Abstract

An electrostatic actuator driving device which has a small size, a light weight, and a high output power, and saves electric power, and a safe helping device which utilizes such a driving device and is movable freely. First and second switching means are controlled to alternately electrically connect the lower-voltage winding of a transformer to the DC voltage source or the high-voltage winding of the transformer to the electrostatic actuator actuating section and electrical energy is repeatedly transferred in an arbitrary direction between a DC voltage source and an electrostatic actuator actuating section.

Description

 Specification

 Electrostatic actuator and assisting device using the same

 Technical field

 The present invention relates to an electrostatic actuator driving device and an assisting device using the same.

 Background art

 Conventionally,? Linear actuators using electromagnetic motors have been used to drive assistive devices for the elderly and the disabled, but the output generated (power) relative to the equipment weight of the actuator is: Because of the low power-to-weight ratio, only small pulses could be generated, and assistance was limited to low, constant speed operations. Such an apparatus is described in, for example, Japanese Patent Application Laid-Open No. 3-17054.

 Therefore, a walking assist device that can flexibly adapt to a user's condition by using an electrostatic actuator having a large weight ratio has been proposed in Japanese Patent Application Laid-Open No. 7-184696. ing. However, in this publication, when using an electrostatic actuator for this device, the conditions for free movement such as small size, light weight, high output and power saving are not sufficiently studied. If an electrostatic actuator is used, a high voltage is required to drive it, so safety measures against this high voltage are also required.

On the other hand, as a conventional electrostatic actuator, there is one described in Japanese Patent Application Laid-Open No. 4-271284. In this electrostatic actuator, the switch means (element) is connected to the DC power supply, and when the switch means is turned on (input), the DC power supply is directly connected to the electrode. It has become. However, such a circuit has a circuit configuration in which an inrush current is generated with respect to the capacitance of the electrode of the electrostatic actuator. It is known that energy loss increases in such a circuit configuration, and the output increases. Attempting to do so further increases energy loss. For this reason, the output obtained from the electrostatic actuator was limited.

 Japanese Patent Application Laid-Open No. 6-785666 discloses an electrostatic actuator in which the voltage of an AC power supply is increased by a transformer, and the efficiency is increased by applying the voltage to an electrode. ing. However, such a device is generally inconvenient to mount on a moving device or equipment because the size and weight of the transformer are large and an AC power supply is required.

 Disclosure of the invention

 Accordingly, a first object of the present invention is to provide an electrostatic actuator that is driven by using a DC power supply and is capable of returning the energy stored in the operating portion of the electrostatic actuator to the DC power supply side. It is in.

 Further, a second object of the present invention is to provide an assistance device that can be used for a long time without being supplied with external power and that can move freely, and can generate a strong force. And there.

 In order to achieve the first object, in the electrostatic actuator of the present invention, a DC power supply and a working part, that is, an electrode of the electrostatic actuator, which is a capacitive load, are connected to the inductive circuit element. Electrically connected alternately.

 At this time, a coil or a transformer can be considered as the inductive circuit element.

 Further, in order to achieve a second object of the present invention, a supporting unit, a unit for detecting a user's force acting on the supporting unit, and a driving unit for driving the supporting unit based on the detected force And an assisting device having the above-mentioned electrostatic actuator and driving the supporting portion.

Since a voltage pulsating at a high frequency is applied to the inductive circuit element, the inductive circuit element, that is, the coil or the transformer can be miniaturized. At this time, the DC power supply and the operating part are separated by a time interval of 50 jus or less, It is preferred that they are alternately connected to the low and high voltage windings of the transformer, respectively.

 The above-mentioned inductive circuit element stores electric energy from the DC power supply and then transfers the electric energy to the operating part of the electrostatic actuator, or after storing electric energy from the operating part of the electrostatic actuator. It acts to transfer that energy to the DC power supply. The operation of returning the electric energy from the working part of the electrostatic actuator to the DC power in this way is called a regenerative operation. In addition, by operating in this manner, it is possible to prevent a rush current to the electrostatic actuator operating portion (electrode) which becomes a capacitive load. Preferred embodiments of the present invention will be described below.

 (a) DC switch, a transformer, an actuating part serving as a capacitive load, and first switch means for connecting a child of the DC power supply and a low voltage side winding of the transformer by selecting a polarity. And a second switch means for selecting and connecting a polarity of the operating portion serving as the capacitive load and a high-voltage side winding of the transformer, wherein the first switch is provided. Means and the second switch means are alternately charged electrostatic actuators.

 (b) a DC switch, a transformer, an operating portion serving as a capacitive load, and first switch means for connecting a terminal of the DC power supply and a low-voltage side winding of the transformer by selecting a polarity. Second switch means for selecting the polarity of the actuating portion serving as the capacitive load and the high-voltage side winding of the transformer and connecting them, and switch control means. The switch control means selects the polarity of the first switch means and the second switch means and turns them on alternately.

(c) a DC power supply, a transformer, an operating part serving as a capacitive load, first switch means for connecting a terminal of the DC power supply and a low-voltage side winding of the transformer, Connects the working part to be a load to the high-voltage side winding of the transformer A second switch means, a switch control means, and a transformer provided with a magnetic sensor.The switch control means controls the DC power supply based on an output of the magnetic sensor. The first switch means and the second switch means for alternately and selectively selecting a polarity to connect the operating portion to a low-voltage side winding of the transformer and a high-voltage winding of the transformer; A static actuator that controls the switch means of the switch.

 In this case, the magnetic sensor includes means and a sensor for detecting the magnitude of the magnetic field by detecting the current flowing through the winding of the transformer.

 (d) a power supply, a transformer, an operating section having electrodes configured to have a plurality of phases, and a polarity of a terminal of the DC power supply and a low voltage side winding of the transformer. First switch means for connecting, second switch means for selecting and connecting the operating part and the high-voltage side winding of the transformer by selecting a polarity, and each phase from the voltage of each phase of the electrode. Means for obtaining a value obtained by subtracting a voltage command value obtained in the second step, wherein the first switch means and the second switch means are switch means which are alternately turned on. In addition, the second switch means passes a current from the high-voltage side winding of the transformer toward the phase having the minimum value, and the high-voltage of the transformer starts from the phase having the maximum value. An electrostatic actuator, which is a switch means that operates so as to flow a current toward the voltage side winding.

 (e) a DC power supply, a coil, an operating part serving as a capacitive load, first switch means for selecting a polarity of the terminal of the DC power supply and connecting the coil, and serving as the capacitive load Second switch means for connecting the operating portion and the coil by selecting a polarity is provided, and the first switch means and the second switch means are alternately turned on. Electrostatic actuator.

(f) a DC power supply, a coil, an operation part serving as a capacitive load, and first switch means for connecting a terminal of the DC power supply to the coil by selecting a polarity. And second switch means for selecting the polarity of the operating portion serving as the capacitive load and connecting the coil, and switch control means.The switch control means comprises: An electrostatic actuator for selectively applying a polarity to the first switch means and the second switch means alternately.

 (g) a DC power supply, a coil, an operation unit serving as a capacitive load, a first switch means for connecting the terminal of the S-current power supply to the coil, and an operation serving as the capacitive load A second switch unit for connecting the unit and the coil, a switch control unit, and a magnetic sensor in the vicinity of the coil. An electrostatic switch for controlling the first switch means and the second switch means to connect either the DC power supply or the operating section to the coil based on the output by selecting a polarity. Actors.

 (h) an AC power supply, a coil, an operating part having an electrode configured to have a plurality of phases, and a first switch for connecting a terminal of the DC power supply and the coil by selecting a polarity. Switch means, second switch means for connecting the operating section and the coil by selecting the polarity, and obtaining a value obtained by subtracting a voltage command value given to each phase from a voltage of each phase of the electrode. Means, wherein the first switch means and the second switch means are alternately turned on, and the second switch means The means is a switch means operable to flow a current from the coil toward the phase having the minimum value and to flow a current from the phase having the maximum value toward the coil.

(i) The DC power supply and the working part are alternately connected to the low voltage side winding and the high voltage side winding of the transformer at time intervals of 50 / is or less, respectively. One. At this time, it is preferable that the DC power supply or the operation unit is connected to the transformer at a time interval of 100 μs or less. DC power supply and working part to transformer If they are connected for the same time, the DC power supply and the working part will be connected to the transformer alternately at a time interval of 50 μS or less. By alternately driving the transformer in such a short cycle, the primary side of the transformer is driven at a sufficiently high frequency, so that the transformer can be downsized.

 Hereinafter, preferred embodiments of the assisting device according to the present invention will be listed.

 (A) an assisting device comprising: a support portion; means for detecting a user's force acting on the support portion; and drive means for driving the support portion based on the detected force. An assistance device comprising the electrostatic actuator according to any one of claims 1 to 8.

 (Mouth) An assisting device comprising: a support portion; means for detecting a user's force acting on the support portion; and drive means for driving the support portion based on the detected force. An assistance device equipped with an electrostatic actuator driven by a battery capable of charging and discharging between 12 V and 60 V.

The above-described electrostatic actuator according to the present invention can be driven by a low-voltage battery by using the electrostatic actuator as an assisting device because it can save power, achieve high efficiency, and obtain a large output.

 BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a circuit diagram showing a first embodiment of the electrostatic actuator driving device of the present invention.

 FIG. 2 is a cross-sectional view illustrating the structure and operation principle of the static actuator.

 FIG. 3 is a perspective view for explaining the structure of a laminated electrostatic actuator. FIG. 4 is a circuit diagram illustrating the operation of the electrostatic actuator driving device in the case of two phases.

FIG. 5 is an operation flow chart of the electrostatic actuator driving device in the case of two phases. FIG. 6 is a graph showing an example of a change in current, voltage, and energy stored in a transformer.

 FIG. 7 is a circuit diagram illustrating the operation of the electrostatic actuator driving device in the case of three or more phases.

 FIG. 8 is an operation flow diagram of the electrostatic actuator driving device in the case of three or more phases.

 FIG. 9 is a diagram showing an example of the assistance device of the present invention.

 FIG. 10 is a cross-sectional view illustrating a structure that enhances safety against electric shock.

 FIG. 11 is a block diagram showing a configuration of an electrostatic actuator equipped with a power smoothing device.

 FIG. 12 is a block diagram showing a first configuration of an electrostatic actuator having a plurality of operating parts.

 FIG. 13 is a partial circuit diagram showing a second embodiment of the electrostatic actuator driving apparatus of the present invention.

 BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 is a circuit diagram showing a first embodiment of an electrostatic actuator driving apparatus according to the present invention. The electrostatic actuator driving device 1 receives the supply of energy from the voltage source 3 and supplies a driving voltage to the n phases P 1 to P n of the electrostatic actuator operating section 2.

The low voltage winding 5 of the transformer 4 is connected to the voltage source 3 via a first switch group 7, and the high voltage winding 6 is connected via a second switch group 8 It is connected to the n phases P 1 to P n of the actuator actuator 2. The number of turns of the high voltage winding 6 is larger than the number of turns of the low voltage winding 5. The first switch group 7 includes bridge-connected electrically controllable switching elements A 1, A 2, B l, and B 2, and selectively turns on and off the switching elements. You As a result, the voltage source 3 can be connected to the low-voltage winding 5 with an arbitrary polarity, or can be disconnected. The second switch group 8 includes 2 × n switching elements C 1 to C n and D l to D n .By selectively turning on and off the switching elements, Any two of the phases Pl to Pn can be selected and connected to the high-voltage winding 6 with any desired polarity, or all phases can be disconnected.

 The voltage comparison device 11 compares the voltages of the phases P1 to Pn obtained by the voltage detector 12 with the voltage command 10 to determine the phase and direction in which the current is applied. The switch control device 9 performs switching based on the stored energy of the transformer 4 detected by the stored energy detector 16 and the phase to which the current determined by the voltage comparison device 11 is applied. Determine the timing for conducting or blocking the elements A l, A 2, B l, B 2, C l to C n, and D l to D n. Switching elements Λ1, A2, B1 to B2, C1 to Cn, and D1 to Dn are, for example, transistors, thyristors, MOS-FETs, IGBTs, and other semiconductors. Switching elements can be used. More preferably, it is desirable to use an intelligent power module in which a switching element and a switching element drive circuit are integrated. Further, in order to protect the switching element, a protection circuit including a coil, a capacitor, a diode and the like may be inserted in series or in parallel with the switching element. Transformer

As for 4, a piezoelectric transformer (piezoelectric transformer) can be used instead of a transformer using a coil. As a method of realizing the stored energy detector 16, there are a method of measuring the magnetic field in the transformer using a magnetic sensor such as a Hall element, and a method of obtaining the value from the winding current of the transformer.

 FIG. 2 is a cross-sectional view for explaining the structure and operation principle of the electrostatic actuator. The electrostatic actuator unit 2 includes a stator 201 and a mover 202. The stator 201 has multiple electrodes 2 on an insulative base 203.

The movable element 202 has a plurality of electrodes on an insulating base 204. 2 0 6 is provided. The plurality of electrodes 205 and 206 are electrically connected to n phases P1 to Pn. In the example of FIG. 2, n = 6. When an AC voltage is generated by the electrostatic actuator driving device 1 and supplied to the phases Pl to Pn, an electrostatic attractive force or a repulsive force is generated between the electrodes 205 and 204. A thrust 208 is generated between the stator 201 and the mover 202. The mover 202 moves relative to the stator 201 by the thrust 208.

 FIG. 3 is a perspective view for explaining the structure of the operation part of the laminated electrostatic actuator. The electrostatic actuator operating section 2 includes a plurality of stators 201 and a plurality of movers 202 which are alternately stacked, and the stator 201 has a connecting section 210 and a mover. 2 0 2 is fixed to the connecting portion 2 1 1. In addition, the plurality of electrodes 205 and 206 provided on the plurality of stators 201 and the mover 202 are electrically connected to n phases P1 to Pn. By supplying a driving voltage to the phases Pl to Pn by the electrostatic actuator driving device 1, a thrust is generated between the adjacent stator 201 and the movable member 202. Then, by adding the thrusts at the joints 210 and 211, a large thrust 208 is generated between the joints 210 and 211.

 In addition, the phase connected to the stator electrode 205 and the phase connected to the mover electrode 205 are connected in reverse order to the common output terminal of the driving device 1 so that the driving is performed. The number of output phases of device 1 can also be reduced. That is, in the example of FIG. 2, by connecting the phases P1 to P3 and the phases P6 to P4, the number of phases of the driving device 1 can be set to three.

The operation of the electrostatic actuator driving device according to the present embodiment will be described in detail with reference to FIGS. 4 and 5 in the case where the number of phases is two. FIG. 4 is an explanatory diagram of the driving device in the case of two phases, and FIG. 5 is an operation flow diagram of the switch control device 9. Since the electrodes of the electrostatic actuator operating section connected to a plurality of phases act as a capacitive load on the driving device, a capacitor having a capacitance C is used here. Represented by load 20. The number of turns of the low-voltage winding 5 of the transformer 4 is n1, the self-inductance is Ll, the number of turns of the high-voltage winding is η2, and the β-inductance is L2. Assuming that the transformer is an ideal transformer with no magnetic flux leakage, the following relationship exists.

L 2 = (n 2 / nl) ² L 1 (Equation 1) When the currents flowing through the low-voltage winding and the high-voltage winding are I 1 and I 2, respectively, the magnetic field energy is stored in the transformer. The following relationship exists between the energy UT and the current that are applied.

UT = (1/2) L 1 1 1 ² + (1/2) L 2I 2 ²

+ (L 1-L 2) ^1/2 I 1-I 2 (Equation 2) The load voltage VL is detected by the voltage detector 12 and the difference calculator 21. In the following, the force for explaining the case of VL 0 is VL. In the case of 0, VL is read as 1 VL, 1 L is read as 1 IL, VR is read as 1 VR, and the switching element C 1.2 is read as 0 1 ′ D The same can be said if it is read interchangeably with 2. This drive operates as follows.

 (1) Transformer energy-accumulation. The regenerative accumulated energy detector 16 detects the accumulated energy UT of the transformer 4 and compares it with a reference value UT0 of the place (step 100). Here, the predetermined reference value U T0 may be set to, for example, about 50% of the energy amount at this time because the amount of energy that can be stored in the transformer is determined by the magnitude of the transformer.

In the case of UT and UT0, turn on the switching elements A1 and B2 and turn off the other elements (step 101) to cut off the current of the high voltage winding 6 and turn off the low voltage winding. Apply the voltage VS of power source 2 to 5. At this time, the current I 1 flows due to the energy stored in the low-voltage winding 5, but the voltage source 2 is connected in a direction to increase the current I 1, so that I 1 increases. Further, the current IS flowing through the voltage source 2 is IS == I1. UT increases according to the increase of I 1 and approaches UT 0. That is, energy is stored from the voltage source 3 to the transformer 4.

 On the other hand, when UT> UTO, the switching elements Α 2 and Β 1 are turned on and the other elements are turned off (step 102), and the current of the high-voltage winding 6 is cut off. Apply a voltage of VS. At this time, the current I 1 flows due to the energy stored in the low-voltage winding 5, but since the voltage source 2 is connected in a direction to reduce this current II,〗 1 decreases and UT decreases. Then approach the UTO. A current of I S = —I 1 flows through the voltage source 2. That is, energy is regenerated from the transformer 4 to the voltage source 3.

Wait until the absolute value of the deviation between UT and UT 0 falls within the predetermined allowable deviation ε (step 103). The allowable deviation _f is appropriately determined, but may be set to 10% or less. This waiting time varies depending on the initial value of U and can be calculated from the initial value of UT. Alternatively, τ can be determined by sequentially detecting UT and comparing it with UT0. Next, the switching elements Al-B1 are turned on and the others are turned off (step 104), and the low-voltage winding 5 is short-circuited. As a result, the current in the low-voltage winding 5 is preserved, and the stored energy UT of the transformer 4 is maintained at a value close to UT0.

Next, it waits for a predetermined time t1 for a time (t1-τ) (step 105). That is, when a predetermined time t1 has elapsed from the start of the operation in (1), the operation proceeds to the next operation. At this time, the predetermined time t 1 is determined from a time constant determined by the inductance of the transformer and the capacitance of the capacitive load. It should be set to a shorter time.

 (2)? 8: Flow output ^ Deviation VE obtained by subtracting command voltage VR from load voltage VL is calculated by difference calculator 22 and compared with predetermined tolerance δ (Steps 106 and 107) . The allowable deviation δ is appropriately determined, but may be set to 10% or less.

 In the case of VE δ, turn on the switching element CI'D 2, turn off the other elements (step 108), cut off the current of the low-voltage winding 5, and load the high-voltage winding 5. Connect to 0.

 As a result, the current I 2 is excited in the high-voltage winding 6 and the current 1 L = I 2 is supplied to the load 20, so that the load voltage VL increases and approaches the voltage command V K. Further, since a voltage in a direction opposite to the current is applied to the high-voltage winding 6, the current I2 decreases, and the stored energy UT of the transformer 4 decreases. That is, energy is supplied from the transformer 4 to the load 20.

 On the other hand, if VE> δ, the switching elements C 2 · I) 1 are turned off and the others are turned off (step 109), so that the current of the low-voltage winding 5 is cut off and the high-voltage winding 6 is turned off. This causes the current 12 to be excited in the high-voltage winding 6 and the current IL = 1-12 to be supplied to the load 20, so that the load voltage VL becomes The voltage decreases and approaches the voltage command VR.In addition, since a voltage in the same direction as the current is applied to the high-voltage winding 6, the current 12 increases and the stored energy UT of the transformer 4 increases. The energy is regenerated from the load 20 to the transformer 4.

 On the other hand, in the case of | V E I, the switching element is not changed, and the low-voltage winding is short-circuited. As a result, the load voltage VL is kept close to the voltage command VR. Also, the energy of the transformer 4 is maintained.

Next, it waits until a predetermined time t2 has elapsed (step 110). t 2 is The resonance period T of the self-inductance L 2 of the high-voltage winding 6 and the capacitance C of the load 20 is sufficiently shorter. here,

T = 2π (L 2 · C) / 2 (Equation 3). Next, the procedure returns to the first operation (step 100).

 Thereafter, the above operations (1) and (2) are repeated at a cycle t c = t l + t 2.

 FIG. 6 shows, by way of example, a graph of a change in UT, VL, and a change in the state of the switching element when a triangular wave is applied to the voltage command VR. In addition, 12 is drawn by enlarging the scale by n 2 Z n l times more than 11.

 Since the first two periods are VL and VR, the pairs of switching elements C 1 -D 2 and A 1 · 2 are turned on alternately to transfer energy from the voltage source to the load via the transformer. ing. In the next two cycles, since V L> V R, the pairs C 2 .D 1 and A 2 · Β 1 are turned on alternately, and energy is transferred from the voltage source to the load via the transformer. As a result, VL is controlled to follow VR. During the entire process, I 1 and I 2 are excited alternately, and UT changes continuously.

 For the sake of explanation, in Fig. 6, switching operation is performed only for four periods for one period of the triangular wave.However, in practice, switching operation is performed sufficiently fast for voltage command changes, Obtain a proper output waveform.

Next, the operation of the electrostatic actuator driving device of the present invention in the case where the number of phases of the electrostatic actuator operating portion as a load is three or more will be described in detail with reference to FIGS. FIG. 7 is an explanatory diagram of the drive device in the case of three or more phases, and FIG. 8 is a flow diagram of the operation of the switch control device 9. Load 20 has multiple phases P 1 ~ P n. Also in this case, the operation (1) (steps 100 to 105) in the case where the number of phases is 2 is performed in the same manner. The above operation (2) (steps 106 to 110) is extended as in the following (2 ').

 (2 ′) Current output The difference V Ei obtained by subtracting the pressure command V R i from the voltage V L i of each phase P i detected by the voltage detector 12 is obtained by the difference calculator 23. The maximum / minimum detector 24 compares the deviations V Ei with a sign, and detects the phase P j having the minimum V E i and the phase P k having the maximum. Also, V E = V E j —V E k is obtained. Here, assuming that VR = VRj-VRk and VL = VLj-VLk, VE = VL-VR holds.

 VE is compared with a predetermined tolerance δ (Step 120), and if IV Ε I> δ, the switching element Cj'Dk is turned on and the other elements are turned off (Step 122). ), Cut off the current in the low voltage winding 5 and connect the high voltage winding 6 to the phases P j and P k of the load 20. As a result, a current 12 is excited in the high-voltage winding 6, and a current 12 is supplied from the phase Pj of the load 20 to the phase Pk. The potential difference VL increases, and VL approaches the potential difference VR of the voltage command of the phase Pj with respect to the phase Pk. When V L ≥ 0, a voltage in the opposite direction to the current is applied to the high-voltage winding 6, so that the current I 2 is small and the stored energy UT of the transformer 4 decreases. That is, energy is supplied from the transformer 4 to the load 20. When V L <0, a voltage in the same direction as the current is applied to the high-voltage winding 6, so that the current I 2 increases and the stored energy U of the transformer 4 increases. That is, energy is regenerated from the load 20 to the transformer 4.

On the other hand, when IVEI ≤ δ, the switching element is not changed and the low-voltage winding is short-circuited. As a result, the potential difference VL of the phase Pj with respect to the phase Pk is kept close to the potential difference VR of the voltage command of the phase Pj with respect to the phase Pk. Further, the energy of the transformer 4 is maintained. Next, it waits until a predetermined time t2 elapses (step 122). t 2 is sufficiently shorter than the resonance period of the self-inductance L 2 of the high-voltage winding 6 and the capacitance of the load 20. Next, the operation returns to the initial operation (step 100). By repeating the above operation at a high speed, it is possible to cause the potential differences of all the phases P 1 to P n to follow the potential difference of the voltage command 10 at a high speed with respect to an arbitrary voltage command 10. Since the thrust generated by the electrostatic actuator operating section is determined by the difference in interrogation potential, the thrust can be controlled by the voltage command 10. In addition, each hook may be grounded via a high resistance in order to make the average ground potential close to zero.

 In the above description, only the switching elements, which are the minimum necessary to allow a desired current to flow through the circuit, are turned on and the others are turned off.However, when the current flowing through the circuit is not affected, the switching elements are turned off. In order to allow time for operation, the switching element may be turned on earlier than required or delayed after being turned off.

 In the above, in order to retain the energy stored in the transformer, a pair of upper and lower switching elements of A 1 -B 1 was turned on and the low-voltage winding 5 was short-circuited. The switching element may be turned on, or the high-voltage winding 6 may be short-circuited.

In this drive device, the switching element is controlled so that the current always flows through only one of the two windings of the transformer, so that the winding is equivalent to the inductance and acts as a current source. No large inrush current to voltage source and capacitive load. Also, since the current in both windings of the transformer is not interrupted, no large surge voltage is generated. Since the switching element is ON or OFF and there is no large inrush current and surge voltage, loss in the circuit is small and large power can be generated without using a large heat sink. In addition, since the energy is moved little by little by operating the switch repeatedly at high speed, the energy stored in the transformer can be smaller than the maximum energy stored in the load, and it is small and lightweight. A large amount of power can be generated using this transformer.

 Also, since the transformer has a boost function, a high voltage can be generated using a low voltage source. Since one transformer has both an energy conversion function from a voltage source to a current source and a voltage conversion function from a low voltage to a high voltage, the circuit configuration is simple, and it can be configured small, lightweight and inexpensive.

 In addition, the reactive power generated when driving a capacitive load and the power generated when an actuator is driven by an external force are regenerated to a voltage source through a transformer. The energy consumption of the voltage source can be reduced. Since a regenerative resistor and a heat sink that consumes excess power are not required, the device can be reduced in size and weight.

 In addition, since the current is applied from the smallest phase to the largest phase with the deviation obtained by subtracting the voltage command for each phase from the voltage of each phase, the potential difference of each phase is applied to any voltage command. It can quickly follow the potential difference of the command.

 As described above, the electrostatic actuator driving device of the present invention is small and lightweight, has high efficiency, has a large output, can use a low-voltage power supply, and can generate a high-voltage arbitrary waveform voltage. High efficiency and use of low-voltage power supply enable long-time operation with small batteries. Also, since high power and large output can be generated, large thrust and large output can be generated in the electrostatic actuator operating section.

Also, if a simple sine wave voltage is applied to the electrostatic actuator operating section to drive it, a large pulsation is generated in the force or speed. Reduce pulsation and smooth Can be operated. Further, the larger the number of phases, the smoother the operation of the electrostatic actuator unit can be performed, but the electrostatic actuator driving device of the present invention can be expanded to any number of phases. Therefore, a multi-phase drive can be realized with a small, lightweight and low-cost circuit.

 In order to reduce the size and weight of the transformer and improve the response to voltage commands, it is desirable that the repetition cycle tc be 1Ο Ο μs or less, and more preferably 20 μs to l / s. . Also, assuming that the maximum value of the interrogation potential difference that can be generated is VLmax, VLmax is in the range of 300 V to 300 V in order to generate a sufficient thrust in the actuator unit of the electrostatic actuator. Hope that there is. Therefore, it is desirable that the switching element has a switching time of 2 μs or less and a withstand voltage of 300 V to 300 V.

 Further, it is desirable that the winding ratio n 2 Z nl of the transformer is close to VL max ZVS, and more preferably, the (n 2 nl) / (VL max / VS) force SO.2 to 5 It is desirable that Under this condition, the time τ required for energy storage and regeneration in the transformer in (1) above is close to the current application time tl to the load in (2), and the second switch group and the second switch Since the operating speed required for the switching elements of the switch group is close, the repetition cycle tc can be shortened by maximizing the performance of the switching elements, contributing to the downsizing and weight reduction of the transformer.

 In addition, in order to maintain a sufficient current during the application of the current to the load in (2) and to reduce the size and weight of the transformer, the resonance period T of the high-voltage winding and the load capacitance must be equal to the current application time t1. It is desirable to set the self-inductance L 2 of the high-voltage winding so as to be in the range of 4 to 40 times. In addition, it is desirable that the reference value U T0 of the energy stored in the transformer is 1 to 10 times the maximum energy transferred during the time t2 in (2).

FIG. 13 shows a second embodiment of the electrostatic actuator driving device of the present invention. FIG. In this embodiment, a high-voltage power supply 60 is provided in place of the voltage source 3 of the first embodiment shown in FIG. 1, and a coil 61 is provided in place of the transformer 4, and a low-voltage winding is provided. Instead of the wire 5 and the high-voltage winding 6, a common coil 61 is connected to the circuit. Although not shown, the switch control device 9, the voltage comparison device 11 and the voltage detector 12 are similarly provided, and the present driving device operates in the same manner as the first embodiment.

 In the present driving device, the current flowing through the switching cables # 1, # 2, Bl, and # 2 is reduced, so that the size of the switching element can be reduced. By using a circuit such as a resonant switching power supply, the high-voltage power supply 60 can be made small, lightweight, and highly efficient. In particular, when a plurality of electrostatic actuator operating sections 2 are provided, the high voltage power supply 60 can be used in common, so that the entire apparatus is reduced in size and weight.

 FIG. 9 (a) is a configuration diagram showing an embodiment of the assistance device of the present invention using the electrostatic actuator driving device of the present invention. The assistance device 30 includes a support portion 32 provided on the arm 31, a linear electrostatic actuator operating portion 2 for driving the arm 31, and the electrostatic actuator of the present invention. A driving device 1 is provided, and a battery is mounted as a voltage source 3. The arm 31 is rotatably mounted on a fulcrum 33 provided on a column 34. The electrostatic actuator operating portion 2 has one end on the column 34 and the other end on the arm 3. It is rotatably mounted on 1 by fulcrums 35 and 36.

 The assisting device 30 includes an acting force detector 38 that detects an acting force 41 acting on the user 37 from the support portion 32 and an assisting control that generates a voltage command to be given to the electrostatic actuator driving device 1. A device 39 is provided so that a part of the weight can be supported in response to the impaired leg strength of the user 37.

The assistance device 30 includes wheels 40 and is configured to be movable. The operation of the assistance device will be described below. FIG. 9 (b) is a control block diagram of the assistance device 30. The acting force 41 acting on the user 37 from the support part 32 is detected by the acting force detector 38. Here, the upward acting force is positive. In the assistance control device 39, the difference between the acting force 41 and the acting force target value 42 is obtained by the subtractor 45, and the difference is multiplied by the gain KV by the multiplier 46, and the electrostatic actuator operating section is obtained. Generate speed command 4 3 for 2. The sign of the gain KV is set so that the support portion 32 is moved upward when the acting force 41 is smaller than the acting force target value 42. Further, the multiplier 47 multiplies the speed instruction 43 by a constant KF determined by the arrangement of the electrodes of the electrostatic actuator operating section 2 to operate the electrostatic actuator operating section 2 in accordance with the speed instruction 43. Generate the frequency command 4 4 for The AC generator 48 generates an AC waveform according to the frequency command 44 and supplies it to the electrostatic actuator driving device 1 as a voltage command 10. As a result, the electrostatic actuator operating section 2 operates according to the speed command 43, and the arm 31 and the support section 32 move in conjunction therewith.

 By the above control, when the acting force 41 is smaller than the acting force target value 42, the support portion 32 moves upward, and when the acting force 41 is larger than the acting force target value 42. Since the support portion 32 moves downward, the acting force 41 approaches the acting force target value 42, and the user 37 can be supported by the force of the acting force target value 42.

 The target force 42 is determined so that a part of the weight is supported according to the degree of the leg weakness of the user 37. As a result, the burden on the leg of the user 37 can be reduced, and the user can easily walk, and at the same time, a decrease in leg strength can be prevented.

As the electrostatic actuator operating section 2, a laminated type configuration shown in Fig. 3 that is small and lightweight and can generate a large output is used. User 3 weighing up to 100 kg In order to cope with the assistance of 7, an assistance force of up to 1 kN is required, but in order to configure the mechanism compactly, the leverage ratio of the arm is 0.5 force> 10 Therefore, it is desirable that the maximum thrust generated by the actuator of the electrostatic actuator be 500 N to 1 O N or less.

 Also, it is desirable to use a battery that can be charged and discharged with a high energy density as the battery used for the voltage source 3, such as a lead storage battery, a nickel-powered dome battery, a nickel hydrogen battery, Lithium batteries can be used.

 Since the actuator of the assisting device according to the present invention uses the static tg actuator, the power weight ratio (output with respect to the equipment weight) is large, and it is small and lightweight. In particular, since the arm is rotationally driven by using a linear electrostatic actuator operating portion, the mechanism is compact.

 Further, since the electrostatic actuator driving device g uses the electrostatic actuator driving device of the present invention, the electrostatic actuator driving device g is small, lightweight, power saving, and high output. In particular, rising and standing T-gags and walking motions include reciprocating movements in the vertical direction, but when moving downward, power is regenerated, further reducing power consumption. Further, since the electrostatic actuator driving device of the present invention has a boosting function, it operates with a low-voltage power supply. Efficiency, low power consumption, and low power supply voltage make it possible to use a small and lightweight battery for power supply for a long time.

As described above, the three elements of the actuator operating section, the actuator drive device, and the power supply, which are all necessary for generating assistance, are reduced in size and weight, so that the entire apparatus can be configured to be small and lightweight. Since the device S is small and lightweight, it can be used for a long time without using external power by using batteries, so it can be freely moved in a variety of environments, such as in a small place like a home or a large outdoor place. It is possible. FIG. Lo is a cross-sectional view illustrating a structure that enhances safety against electric shock. The stacked electrostatic actuator operating section 2 having a plurality of stators 203 and movable elements 204 and the electrostatic actuator driving device 1 are housed in a common insulating case 50, and are connected to the voltage source 3. Have been. The electrostatic actuator driving device 1 is supplied with power from the voltage source 3 and applies a high voltage for driving to the electrostatic actuator operating unit 2.

 Since the electrostatic actuator driving device according to the present invention has a boosting function, the voltage of the voltage source 3 can be set to a low voltage, and the high voltage application portion is minimized in the insulating case. Because it is within the range, high safety against electric shock is obtained. Since the electrostatic actuator driving device of the present invention is small and lightweight, the compact and lightweight nature of the electrostatic actuator is not impaired even in this configuration.

 For safety, it is desirable that the voltage of the voltage source 3 be less than or equal to DC 60 V, which is a safety extra-low voltage specified in JIS-T1001, and limit the current consumption. Therefore, it is desirable that the voltage be 12 V or more.

 FIG. 11 is a block diagram of an electrostatic actuator equipped with a power smoothing device. An electric power smoothing device 51 having a smoothing capacitor 52 and a charge / discharge control device 53 is inserted between the electrostatic actuator driving device 1 connected to the electrostatic actuator operating portion 2 and the voltage source 3. Have been. The charge / discharge control device 53 supplies the power from the voltage source 3 to the smoothing capacitor 52 or the power from the smoothing capacitor 52 to the voltage source 3 so that the voltage of the smoothing capacitor 52 falls within a predetermined range. Regenerate. The electrostatic actuator driving device 1 receives power supply from the smoothing capacitor 52 instead of the power source, and regenerates surplus power to the smoothing capacitor 52.

The charge / discharge control device 53 uses, for example, the same circuit configuration as the two-phase electrostatic actuator drive device shown in FIG. 4 and uses a smoothing capacitor as the load 20. It is realized by connecting 52. As the smoothing capacitor 52, it is desirable to use an electrolytic capacitor having a large capacity and an electric double layer capacitor.

 By inserting the power smoothing device fi, the maximum value of the current flowing through the voltage source is reduced, so that the load on the voltage source is reduced. In addition, since the frequency of charging and discharging of the battery used for the voltage source is reduced, the memory effect is prevented, and the life of the battery is prolonged. In addition, since high-frequency current is reduced and the generation of electromagnetic noise is suppressed, malfunctions of surrounding electronic circuits are prevented, and safety is improved. FIG. 12 is an explanatory diagram of two types of configurations of an electrostatic actuator having a plurality of operating sections. In the configuration shown in FIG. 12, the plurality of electrostatic actuator driving devices 1 connected to the plurality of electrostatic actuator operating sections 2 are connected to the plurality of power smoothing devices 51, respectively. They are connected to a common voltage source 3. With this configuration, the portion where the high-frequency current flows can be kept within the minimum range, and the generation of electromagnetic noise is reduced. On the other hand, a common power smoothing device 51 is provided, and a plurality of electrostatic actuator driving devices 1 respectively connected to the plurality of electrostatic actuator operating units 2 are connected to the common power smoothing device 51. You may do it. With such a configuration, since only one power smoothing device 51 is required, the load on the voltage source 3 can be reduced by a small and low-cost device.

 It should be noted that the electrostatic actuator driving device according to the present invention is connected to a capacitive load such as a piezoelectric element or an ultrasonic motor instead of the electrostatic actuator operating section, and is applied to drive them. Can also. Further, the configuration of the assisting device of the present invention can be applied to a mechanical device such as a robot and a manipulator.

An electrostatic actuator according to the present invention controls a switch group to control a low-voltage winding and a voltage source of a transformer or a high-voltage winding and an electrostatic actuator. Since the actuators are electrically connected alternately, the electrostatic actuator, which is a capacitive load, can be driven with high efficiency, and at the same time, the voltage can be increased to generate a high voltage. In addition, the surplus energy generated in the electrostatic actuator operating section can be regenerated to the voltage source, which saves power. Since the switching means is switched at high speed, large power can be generated using a small transformer. Since the transformer is small and a large heat sink is not required, it is small and lightweight.

 Since the current is applied from the smallest phase to the largest phase of the voltage command of the electrostatic actuator operating section and the deviation of the corresponding voltage command from the minimum phase, the multiple phases of the electrostatic actuator operating section are applied. Potential difference of voltage command to potential difference? You can follow quickly.

 Since a low-voltage power supply is used, and the drive unit is housed in an insulating case common to the electrostatic actuator operating unit, the risk of electric shock is low and it is safe.

Claims

The scope of the claims 1. A first switch for connecting a DC power supply, a transformer, an operating part serving as a capacitive load, and a terminal of the DC power supply to a low voltage follower of the transformer by selecting a polarity. _U-means, and a second switch-stage for selecting and connecting a polarity of the operating part serving as the capacitive load and the high-voltage side winding of the transformer. exchange ⁷ and the second sweep rate Tutsi means sweep rate Tutsi means i: thrown into electrostatic Akuchueta characterized and Turkey "  2. A DC power supply, a transformer, an operation part serving as a capacitive load, and a first switch for selecting and connecting a terminal of the DC power supply and a low-voltage side winding of the transformer with a selected polarity. Means, second switch means for selecting the polarity and connecting the actuating portion serving as the capacitive load and the ¾ ¾ side winding of the transformer by selecting polarity, and switch control means. Wherein the switch control means selects the polarity and alternately turns on the first switch means and the second switch means, and switches on the first switch means and the second switch means. Ta. 3. a DC power supply, a transformer, a capacitive working part, a first switch means for connecting a terminal of the DC power supply to a low-voltage side winding of the transformer, A second switch means for connecting an operating portion serving as a load and a high-voltage side winding of the transformer, switch control means, and a magnetic sensor in the transformer, wherein the switch comprises: Based on the output of the magnetic sensor, the DC power supply is alternately and polarity-changeably connected to the low-voltage side winding of the transformer, and the operating section is connected to the high-voltage side winding of the transformer. An electrostatic actuator characterized by controlling said first switch means and said second switch means to select and connect. 4. A DC power supply, a transformer, an operating part having electrodes configured to have a plurality of phases, and a polarity of a terminal of the DC power supply and a low voltage side winding of the transformer are selected. First switch means for connecting and connecting, the operating part and the transformer Second switch means for selecting the polarity of the high-voltage side winding and connecting the same, and means for calculating a value obtained by subtracting a voltage command value given to each phase from the voltage of each phase of the electrode. The first switch means and the second switch means are switch means which are alternately turned on, and the second switch means further comprises the transformer A switch that operates so that current flows from the high-voltage side winding of the transformer toward the phase having the smaller value, and the current flows from the largest phase to the high-voltage side winding of the transformer. An electrostatic actuator characterized by being a means.  5. DC power supply, coil, operating part serving as a capacitive load, first switch means for connecting the terminal of the DC power supply and the coil by selecting a polarity, and operation serving as the capacitive load And a second switch means for selecting the polarity of the coil and the coil and connecting the first switch means and the coil, wherein the first switch means and the second switch means are alternately turned on. An electrostatic actuator characterized by the above. 6. A DC power supply, a coil, an operation part serving as a capacitive load, first switch means for selecting and connecting a terminal of the DC power supply and the coil by selecting a polarity, and an operation serving as the capacitive load A second switch for selecting a polarity between the unit and the coil, and switch control means, wherein the switch control means comprises: the first switch. And a second switch means. The electrostatic switch is configured to select a polarity and to alternately supply the second switch means and the second switch means. 7-DC power supply, coil, operating part serving as capacitive load, first switch means for connecting a terminal of the DC power supply to the coil, operating part serving as the capacitive load, and the coil , Switch control means, and a magnetic sensor in the vicinity of the coil, wherein the switch control means, based on an output of the magnetic sensor, Before the coil An electrostatic actuator characterized by controlling the first switch means and the second switch means to connect either the DC power supply or the operating section by selecting a polarity. One.  8-a power supply, a coil, an actuating section having electrodes configured to have a plurality of phases, a terminal of the DC power supply, and a front end; A switch means for selecting the polarity of the operating section and the coil, and a value obtained by subtracting a voltage command value obtained for each phase from the voltage of each phase of the electrode. The first switch means and the second switch means are switch means which are alternately turned on, and further comprise the second switch means. The means is switch means operable to flow a tortoise from the coil toward the phase having the minimum value and to flow current from the phase having the maximum value to the coil. Characteristic electrostatic actuator.  9.It is characterized by being connected alternately to the low voltage side winding and high voltage side winding of the transformer, respectively, at a time interval of 50 s or less with the power supply, the working part and the power less than 50 s. Electrostatic actuator.  10. An assisting device comprising: a support portion; a means for detecting a user's force acting on the support portion; and a drive means for driving the support portion based on the detected force. An assistance device comprising the electrostatic actuator according to any one of claims 1 to 8.  11. An assisting device comprising: a support portion; means for detecting a user's force acting on the support portion; and drive means for driving the support portion based on the detected force. An assisting device comprising an electrostatic actuator driven by a chargeable / dischargeable battery of 12 V or more and 60 V or less.