JP2008141357A - Pwm driver and drive method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PWM driver and a PWM drive method, exhibiting a gain stabilized with respect to the temperature without the need to increase the chip area or require post-processes, such as trimming. <P>SOLUTION: The PWM driver comprises a first voltage/current converter 6 for converting a command voltage into current; a voltage divider 5 for dividing the voltage between the output terminals; a second voltage/current converter 7 for converting the output voltage from the voltage divider into current; a capacitor C, having one end connected with the joint of the output of the first voltage/current converter and the output of the second voltage/current converter; an amplifier 8 for amplifying the terminal voltage of the capacitor; a triangular wave generator 9 generating triangular waves, having a phase difference of 180 degrees; a first comparator 10a for comparing one triangular wave, with reference to the output voltage from the amplifier; a second comparator 10b for comparing the other triangular wave with reference to the output voltage from the amplifier; and a drive circuit 11 for driving a load connected to the output terminal, according to the outputs from the first and second comparators. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a PWM drive device such as an electromagnetic actuator, and more particularly to a PWM drive device constituted by a semiconductor or a semiconductor integrated circuit.

  The PWM drive system is a means of reducing power consumption in driving an electromagnetic actuator, for example, for driving an electromagnetic actuator such as an optical disc player focus and tracking, tilt control actuator, spindle motor or pickup feed motor. Widely used. These drive circuits are generally commercialized as semiconductor integrated circuits in which the main parts are integrated into one semiconductor chip, contributing to the reduction in size and weight of the drive device itself.

  Such conventional techniques are disclosed in, for example, Patent Documents 1 and 2. Below, the prior art mainly described in Patent Documents 1 and 2 will be described with reference to FIGS.

FIG. 7 is a circuit diagram showing a configuration of the PWM drive device 101 disclosed in Patent Documents 1 and 2. The PWM drive device 101 supplies power for driving a load 102 corresponding to an electromagnetic actuator for focus, tracking, and tilt control of an optical disc player. The voltage V _in generated by the power supply 103 is a command voltage that commands the average drive voltage of the load 102. A series circuit forming a lag lead filter including resistors Ra and Rb having a predetermined value and a capacitor C is connected to the input terminal IN_, and a connection point between the resistor Ra and the resistor Rb is connected to an input of the amplifier 104. Connected.

  The triangular wave generated from the triangular wave oscillator 106 and the output of the amplifier 104 are input to the first comparator 107, and the output of the amplifier 104 is PWM-modulated. Further, a part of the output of the amplifier 104 is input to the inverter 105 and is inverted by a gain of 1 with reference to the average value of the triangular wave signal. The triangular wave generated from the triangular wave oscillator 106 and the output of the inverter 105 are input to the second comparator 108, and the inverted signal of the output of the amplifier 104 is PWM-modulated. The outputs of the first and second comparators 107 and 108 are input to the first and second pre-drivers 109 and 110, respectively.

  The first and second output circuits 111 and 112 form an H-bridge circuit together with the built-in transistor and the load 102, respectively. The built-in transistors are turned on / off according to the drive signals output from the first and second pre-drivers 109 and 110, respectively, and the load 102 connected to the output terminal FO_ and the output terminal RO_ is supplied with power to be driven. .

On the other hand, a differential input type voltage-current converter 113 is further connected to the output terminals FO_ and RO_. The voltage-current converter 113 outputs a current proportional to the differential voltage between the terminal voltages V _FO and V _RO of the output terminals FO_ and RO_ to the connection point between the resistor Rb and the capacitor C. The lag lead filter including the voltage-current converter 113, the resistors Ra and Rb, and the capacitor C forms a feedback circuit that converts the output terminal voltage V _FO -V _RO into a current and returns it to the input side.

  8 shows the amplifier 104, the triangular wave oscillator 106, the inverter 105, the first and second comparators 107 and 108, the first and second pre-drivers 109 and 110, and the first and second output circuits shown in FIG. 11 is a circuit configuration diagram in which a drive system 114 including up to 111 and 112 and a load 102 are equivalently replaced using two blocks. The gain block 114 a is a block that represents the total gain obtained by excluding the triangular wave oscillator 105 and the first and second comparators 107 and 108 from the load 102 and the drive system 114 in FIG. 7 as G. The modulation degree block 114b determines the modulation degree by the triangular wave oscillator 106, the inverter 105, and the first and second comparators 107 and 108 in the drive system 114 of FIG. It is a block expressed as ≦ M ≦ 1).

In FIG. 8, when the transconductance of the voltage-current converter 113 is gm, the gain G _close of the entire drive circuit is as shown in ( _Equation 1).

The load 102 is driven with a voltage corresponding to the command voltage according to the gain of (Equation 1). That is, the gain of the drive circuit is determined by the resistance value Ra and the transconductance gm of the voltage / current converter 113.
Japanese Patent No. 3803437 Japanese Patent Laid-Open No. 54-100653

  In FIG. 8, the gain of the entire driving device is determined according to the transconductance gm of the voltage-current converter 113 and the resistance Ra in the lag lead filter according to (Equation 1). When the driving circuit is realized by a semiconductor integrated circuit, the transconductance value of the voltage-current converter is determined as the operation of the semiconductor circuit. The resistance value is determined by the dimensions and materials.

  In order to accurately reproduce these values and realize a stable gain as a driving device, conventionally, a resistance element or a semiconductor element in a semiconductor circuit constituting a voltage-current converter or a resistance element, particularly an element related to differential operation For example, by making the dimensions as large as possible, it was possible to reduce variations in electrical resistance caused by errors in the formation dimensions of semiconductor elements, and to reduce variations in voltage and current in the circuit. In addition, a method of correcting the voltage / current to a predetermined value by changing a circuit constant by a method such as laser trimming is widely used.

  However, the method for increasing the size of the semiconductor element conflicts with the recent reduction in power consumption due to process miniaturization and cost reduction due to the reduction in chip area, and the increase in power consumption and cost increase due to increase in chip area. It was inevitable. In addition, correction of circuit constants such as laser trimming also requires considerable labor and time because data such as offsets are individually measured and trimmed, and an increase in working time and cost is inevitable.

  In addition, since the temperature coefficients of the semiconductor element and the resistance element are generally different, the temperature coefficients of the transconductance and the resistance are also different. For this reason, it is inevitable that fluctuations and variations in the gain of the driving device itself due to temperature occur.

  The present invention has been made in view of the above circumstances, and provides a PWM drive device and a PWM drive method having a gain stable with respect to temperature, without increasing the chip area, requiring no post-process such as trimming, and the like. The purpose is to do.

  In order to solve the above problems, a PWM drive device according to the present invention includes a first voltage-current converter that converts a command voltage into a current, a voltage divider that divides a voltage between output terminals, and an output voltage of the voltage divider. A voltage-to-current converter, a capacitor having one end connected to a connection point between the output of the first voltage-current converter and the output of the second voltage-current converter, and the capacitor An amplifier that amplifies the terminal voltage of the amplifier, a triangular wave generator that generates triangular waves that are 180 degrees out of phase with each other, a first comparator that compares one of the triangular waves with reference to the output voltage of the amplifier, and the output of the amplifier A second comparator for comparing a voltage with the other triangular wave as a reference; and a drive circuit for driving a load connected to an output terminal according to the outputs of the first and second comparators.

The PWM driving method according to the present invention includes a first voltage-current conversion step that converts a command voltage into a current, a voltage dividing step that divides a voltage between output terminals, and a first voltage that converts the output voltage of the voltage dividing step into a current. Two voltage-to-current conversion steps; an integration-type voltage conversion step for storing the current output of the first voltage-current conversion step and the current output of the second voltage-current conversion step in a common capacitor and converting the voltage into a voltage; An amplification step for amplifying the terminal voltage of the capacitor;
A triangular wave generating step that generates triangular waves that are 180 degrees out of phase with each other, a first comparing step that compares one triangular wave output from the triangular wave generating step with reference to the output voltage of the amplifying step, and the output of the amplifying step A second comparison step for comparing voltages with reference to the other triangular wave output from the triangular wave generation step, and a drive for driving a load connected to an output terminal in accordance with the outputs of the first and second comparison steps Steps.

  According to the PWM drive device and the PWM drive method of the present invention, the command voltage and the divided output terminal voltage are input to separate voltage-current converters, and one end of the capacitor is connected to the connection point of the outputs of both voltage-current converters. Are connected, PWM modulation and driving are performed based on the voltage obtained by amplifying the terminal voltage of the capacitor with an amplifier, and the gain is determined only by the voltage division ratio by the voltage divider.

  The formation dimension error of the resistor that determines the voltage division ratio formed in the semiconductor chip and the temperature change all have the same tendency. Therefore, even if an error occurs in individual resistance values, the mutual ratio of the resistance values does not change. Therefore, the resistance voltage dividing ratio, that is, the gain of the driving device does not vary. For this reason, it is not necessary to increase the chip area and suppress the formation dimension error of the resistor, and a subsequent process such as trimming is not required, and a stable gain can be maintained with respect to temperature.

  In the PWM drive device of the present invention having the above-described configuration, the triangular wave generator can be configured by one triangular wave oscillator and an inverter.

  Alternatively, the triangular wave generator may be composed of one triangular wave oscillator and a differential output amplifier.

  The voltage divider can be constituted by a voltage divider circuit constituted by two or more resistors.

  Alternatively, the voltage divider is configured by a first voltage divider and a second voltage divider provided for each output terminal, and the second voltage-current converter is configured by the first voltage divider and the second voltage divider. A difference between the output voltages of the voltage divider can be converted into a current.

  The driving circuit includes first and second pre-drivers to which outputs of the first and second comparators are input, respectively, and two switching elements driven by the first and second pre-drivers, respectively. The first and second output circuits may be configured, and an H-bridge circuit may be configured by the first and second output circuits and the load.

  The first and second voltage / current converters may have the same transconductance.

  A plurality of PWM drive devices having any one of the above configurations may be provided, and the triangular wave generator may be shared by the plurality of PWM drive devices.

  Hereinafter, a PWM drive device and a PWM drive method according to embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a circuit diagram showing a configuration of PWM drive device 1a according to the first embodiment of the present invention. FIG. 2 is a waveform diagram showing a time lapse of signals of each part of the driving device of FIG. 1 in the normal mode.

The PWM drive device 1 a supplies power for driving the load 2. Voltage V _in the generation of power supply 3, a command voltage for commanding the input from the input terminal IN_ average drive voltage of the load 2 of the PWM drive device 1a. The command voltage Vin and the reference voltage V _refA output from the power supply 4 are input to the negative input and the positive input of the first voltage-current converter 6, respectively.

On the other hand, the voltages V _Rd and V _Fd respectively input to the negative input and the positive input of the second voltage-current converter 7 are generated as follows. That is, the terminal voltages V _FO and V _{RO of} the output terminals FO_ and RO_ are input to the voltage divider 5. Inside the voltage divider 5, three resistors Rx, Ry, Rz are connected in series, an output terminal RO_ is connected to one end of the resistor Rx, and an output terminal FO_ is connected to one end of the resistor Rz. The voltage V _{Rd at} the connection point between the resistor Rx and the resistor Ry is connected to the negative input of the second voltage-current converter 7. Similarly, the voltage V _{Fd at} the connection point between the resistors Ry and Rz is connected to the plus input of the second voltage-current converter 7. Here, Rx, Ry, and Rz are used as symbols indicating resistance and also as symbols indicating the resistance value. With the above configuration, the both-ends voltage V _Fd −V _Rd of the resistor Ry is Ry / (Rx + Ry + Rz) times the terminal voltage V _FO −V _RO .

  The first and second voltage / current converters 6 and 7 in the present embodiment have predetermined transconductances gm1 and gm2, respectively, and convert the differential voltage between the positive input and the negative input into a current and output the current. The outputs of the first and second voltage / current converters 6 and 7 are connected to each other, and one end of the capacitor C and the input of the amplifier 8 are also connected to the connection point.

The capacitor C receives the respective current outputs of the first voltage-current converter 6 and the second voltage-current converter 7 and generates a wiring potential V _fb . The wiring potential V _fb functions as a negative feedback process in which the feedback voltage (current) is added to the command voltage (current) whose polarity has been inverted, and an integration process in which the current is stored and output as a voltage. It also provides an effect of smoothing the generated harmonic noise component.

In the present embodiment, the amplifier 8 amplifies the wiring voltage V _fb corresponding to the stored voltage of the capacitor C with a predetermined gain. If necessary, the output voltage may be a differential output between an input voltage and a reference potential (not shown).

  The triangular wave generator 9 includes a triangular wave oscillator 9a and an inverter 9b. A part of the triangular wave TRWR output from the triangular wave oscillator 9a is input to the inverter 9b, and is output as another triangular wave TRWF in which the output waveform is inverted without changing the amplitude and the average value. The triangular waves TRWF and TRWR are triangular waves whose amplitude and offset are both predetermined values and whose phases are different from each other by 180 degrees.

The triangular wave TRWF is inputted to the plus input of the first comparator 10a in the PWM modulator 10, and the output voltage V _OF of the amplifier 8 is inputted to the minus input. The output voltage V _OF of the amplifier 8 is inputted to the plus input of the second comparator 10b, and the triangular wave TRWR is inputted to the minus input. Therefore, PWM modulation is performed by comparing the output voltage V _OF with the two triangular waves, and the first and second comparators 10a and 10b output drive signals DSF and DSR, respectively.

  The output circuits 11c and 11d in the drive circuit 11 are configured by a half bridge circuit using two switching elements such as transistors and MOSFETs, and the output circuits 11c and 11d and the load 2 form an H bridge circuit. The pre-drivers 11a and 11b generate appropriate drive signals FH, FL, RH, and RL for driving the switching elements in the output circuits 11c and 11d. When the drive signals DSF and DSR are respectively input, the pre-drivers 11a and 11b output drive signals FH, FL, RH, and RL, respectively. The output circuits 11c and 11d perform switching operations according to the drive signals FH, FL, RH, and RL, and power is supplied to the load 2 from the output terminals FO_ and RO_ to which the outputs of the output circuits 11c and 11d are connected.

FIG. 2A is a waveform showing the command voltage V _in ( _{expressed in} the form of V _in −V _refA ) _in FIG. 1 in the normal mode. (B) shows the wiring voltage V _fb . (C) shows the amplifier output voltage V _OF and triangular waves TRWF and TRWR. (D) and (e) show drive signals DSF and DSR, respectively. (F) and (g) indicate terminal voltages V _FO and V _RO , respectively. (H) shows the time lapse of the output terminal voltage V _FO -V _RO . Triangular wave TRWF, the amplifier output voltage V _OF is subjected to PWM modulation by TRWR, finally output terminal voltage V _FO, V _RO is an output that is PWM modulated, and time average of the PWM cycle, the command voltage V _in It turns out that it becomes a similar shape.

3 shows the amplifier 8, the triangular wave oscillator 9a, the inverter 9b, the first and second comparators 10a and 10b, the first and second pre-drivers 11a and 11b, and the first and second output circuits shown in FIG. It is a figure which shows the circuit structure which replaced the drive system 12 and load 2 including 11c and 11d equivalently using two blocks. The gain block 12a represents the total gain excluding the load 2 and the triangular wave oscillator 9a, the inverter 9b, and the first and second comparators 10a and 10b of the drive system 12 in FIG. ₁ as G1. Modulation block 12b is a triangular wave oscillator 9a of the driving system 12 Figure 1, inverter 9b and the first and second comparators 10a, the degree of modulation by 10b, modulation M ₁ independently of the total gain G ₁ ( Usually expressed as 0 ≦ M ₁ ≦ 1).

In FIG. 3, when the transconductances of the first and second voltage-to-current converters 6 and 7 are gm1 and gm2, respectively, and the capacitance of the capacitor C is C, the gain _Gclose of the entire drive circuit 1 finally becomes (Equation 2 )

つまり、駆動回路１のゲインは、分圧器５の抵抗Ｒｘ、Ｒｙ、Ｒｚの比および第１および第２の電圧電流変換器６、７のトランスコンダクタンスｇｍ１、ｇｍ２の比で決定される。

That is, the gain of the drive circuit 1 is determined by the ratio of the resistors Rx, Ry, Rz of the voltage divider 5 and the ratio of the transconductances gm1, gm2 of the first and second voltage-current converters 6, 7.

  In general, the value of transconductance varies depending on the operating point of the semiconductor circuit constituting the voltage-current converter, the temperature, or a dimension forming error when forming the semiconductor circuit. However, the first and second voltage / current converters 6 and 7 are formed close to each other on the semiconductor chip, and the transconductance gm1 of the first and second voltage / current converters 6 and 7 is taken. By setting gm2 to the same value, it is possible to make the fluctuation rates of gm1 and gm2 substantially the same due to the operating point, temperature, dimensional formation error when forming the semiconductor circuit, and the like. As a result, the gain of the drive circuit 1 is not affected by the transconductance variation of the first and second voltage-current converters 6 and 7. Similarly, the resistors Rx, Ry, and Rz can be formed close to each other to have substantially the same rate of variation due to temperature and dimension formation errors when forming the semiconductor circuit. Therefore, the drive circuit 1 of the present embodiment has a stable gain, and the gain can be determined only by the resistance ratio of the voltage divider 5.

(Embodiment 2)
FIG. 4 is a circuit configuration diagram of the PWM drive device 1b according to the second embodiment of the present invention. In FIG. 4, the same elements as those of the PWM drive device 1a in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will not be repeated. 4 differs from the first embodiment in FIG. 1 in that the voltage divider 5 in FIG. 1 is changed to a voltage divider 13 and that the triangular wave generator 9 is changed to a triangular wave generator 14. is there.

That is, the voltage divider 5 in FIG. 1 directly _{divides the} output terminal voltage V _FO -V _RO by a series resistance, whereas in FIG. 4, the voltage divider 13 respectively outputs the output terminal voltages V _FO and V _RO . Divide pressure between ground. Further, the triangular wave generator 14 is configured by using a differential output amplifier 14b instead of the inverter 9b of FIG. The other elements are the same as those in the first embodiment shown in FIG.

In FIG. 4, the voltage divider 13 includes first and second voltage dividers 13a and 13b, and terminal voltages V _FO and V _{RO at} output terminals FO_ and RO_ are applied to the first and second voltage dividers 13a and 13b, respectively. Each is entered. Inside the first voltage divider 13a, two resistors R1f and R2f are connected in series, and the connection point of the resistors R1f and R2f is connected to the plus input of the second voltage-current converter 7. The other end of the resistor R1f is grounded, and the other end of the resistor R2f is connected to the output terminal FO_. Similarly, in the second voltage divider 13b, two resistors R1r and R2r are connected in series, and the connection point of the resistors R1r and R2r is connected to the negative input of the second voltage-current converter 7. The other end of the resistor R1r is grounded, and the other end of the resistor R2r is connected to the output terminal RO_.

With the above configuration, the output voltages V _Fd and V _Rd of the first and second voltage dividers 13a and 13b are output terminals assuming that the resistance values of the resistors are R1f = R1r = R1 and R2f = R2r = R2. The voltage V _FO and V _RO are R1 / (R1 + R2) times. Due to the differential operation of the input voltage in the second voltage-current converter 7, the difference between the output terminal voltages V _FO and V _RO divided by R1 / (R1 + R2) times, that is, the voltage between the output terminals. A current proportional to the pressure is output from the second voltage-current converter 7. As in the first embodiment of FIG. 1, it can be seen that a current proportional to the voltage between the output terminals is output from the second voltage-current converter 7.

On the other hand, the triangular wave generator 14 includes a triangular wave oscillator 14a and a differential output amplifier 14b. A triangular wave with an average value of 0 oscillated by the triangular wave oscillator 14a is input to the differential output amplifier 14b, and triangular waves TRWF and TRWR having both predetermined amplitudes and offsets and phases different from each other by 180 degrees are output. The triangular wave TRWF is inputted to the plus input of the first comparator 10a in the PWM modulator 10, and the output voltage V _OF is inputted to the minus input. The output voltage V _OF of the amplifier 8 is input to the plus input of the second comparator 10b, and the triangular wave TRWR is input to the minus input, and PWM modulation is performed by comparing the output voltage V _OF with the two triangular waves.

  The differential output amplifier 14b outputs an inverted output and a non-inverted output with the same amplitude and the same timing with respect to the differential input signal. Moreover, the circuit of the inverting output and the non-inverting output is made symmetrical, and has a feature that the differential balance is excellent. In this embodiment, since a triangular wave is input, the phase difference is 180 degrees. It is assumed that the differential output amplifier 14b in the present embodiment has an output offset voltage having the same sign and the same value for both the inverted output and the non-inverted output.

5 is similar to FIG. 3 in that the amplifier 8, the triangular wave oscillator 14a, the differential output amplifier 14b, the first and second comparators 10a and 10b, the first and second pre-drivers 11a and 11b in FIG. FIG. 5 is a circuit configuration diagram in which the drive system 15 including the first and second output circuits 11c and 11d and the load 2 are equivalently replaced using two blocks. Gain block 15a represents the triangular wave oscillator 14a of the load 2 and the drive system 15 of FIG. 4, the differential output amplifier 14b, the first and second comparators 10a, the total gain, excluding 10b as G _2. Modulation block 15b is a triangular wave oscillator 14a of the drive system 15 of FIG. 4, the differential output amplifier 14b and the first and second comparators 10a, the degree of modulation by 10b, modulation independently of the total gain G ₂ M ₂ (Normally 0 ≦ M ₂ ≦ 1).

In FIG. 5, the transconductances of the first and second voltage-current converters 6 and 7 are gm1 and gm2, the capacitance of the capacitor C is C, and the resistance value of each resistor is R1f = R1r = R1, R2f = R2r = R2 , The gain G _close of the entire drive circuit finally becomes (Equation 3).

  That is, the gain of the drive circuit 1b is determined by the ratio of the resistance of the voltage divider 13 and the ratio of the transconductances gm1 and gm2 of the voltage / current converters 6 and 7. As in the first embodiment, by making the transconductances gm1 and gm2 of the voltage-current converters 6 and 7 the same, the gain of the drive circuit 1b is not affected by temperature changes, semiconductor dimension formation errors, etc. The gain of the drive circuit 1b can be set only by the resistance ratio.

(Embodiment 3)
FIG. 6 is a circuit configuration diagram of the PWM drive device according to the third embodiment of the present invention. The present embodiment relates to a configuration for driving a plurality of loads. Drive blocks 20, 21, and 22 shown in FIG. 6 have a configuration in which a triangular wave generator is separated from the PWM drive device in the first or second embodiment, and drives loads 23, 24, and 25, respectively. Command voltage power supplies 26, 27, and 28 are connected to the drive blocks 20, 21, and 22, respectively. On the other hand, the output of the triangular wave center generator 29 is shared by the three drive blocks 20, 21 and 22.

  The triangular wave center generator 29 supplies triangular waves TRWF and TRWR having both predetermined amplitudes and offsets and phases different from each other by 180 degrees to the drive blocks 20, 21, and 22. Each drive block 20, 21, 22 does not have a triangular wave generator, and even if two triangular waves TRWF and TRWR are supplied to each drive block 20, 21, 22 in parallel by one triangular wave central generator 29, The operation of the drive blocks 20, 21, and 22 is not adversely affected. Therefore, it is possible to reduce a circuit corresponding to an extra triangular wave generator.

  In each embodiment of the present invention, the voltage divider is configured using a resistor. However, the voltage divider is not limited to a resistor, and a semiconductor circuit such as an electronic volume or a switched capacitor circuit may be used.

  In addition, regarding the connection between the outputs of the first and second voltage-current converters 6 and 7 and the input of the capacitor C and the amplifier 8, any other element can be inserted in an arbitrary path. For example, a grounded capacitor and a resistor are connected to the output of the second current-voltage converter 12, and the other end of the resistor is connected to the output of the first current-voltage converter 11 and the input of the amplifier 8, and an appropriate circuit constant is set. By setting, it is possible to add effects such as expanding the operating frequency range of the drive circuit and preventing oscillation.

  In addition, the operations of a voltage-current converter, a triangular wave generator, a capacitor, an amplifier, a comparator, and the like may be realized using a microcomputer or software.

  The method used for the drive circuit is not limited to the H-bridge circuit, and other circuit methods may be used.

  The PWM drive device and the PWM drive method according to the present invention do not require a subsequent process such as trimming without increasing the chip area, and can have a stable gain with respect to temperature. Useful for multi-phase motors.

The circuit block diagram of the PWM drive device in Embodiment 1 of this invention Operation waveform diagram of signal of each part of the PWM drive device Circuit configuration diagram in which the drive system and load of the PWM drive device are equivalently replaced using two blocks The circuit block diagram of the PWM drive device in Embodiment 2 of this invention Circuit configuration diagram in which the drive system and load of the PWM drive device are equivalently replaced using two blocks Circuit configuration diagram of PWM drive apparatus according to Embodiment 3 Circuit diagram of a conventional PWM drive device Circuit configuration diagram in which the drive system and load of the PWM drive device are equivalently replaced using two blocks

Explanation of symbols

1a, 1b, 101 PWM drive device 2, 102 Load 3, 4, 103 Power supply 5, 13 Voltage divider 6 First voltage-current converter 7 Second voltage-current converter 8, 104 Amplifier 9, 14 Triangular wave generator 9a , 14a, 106 Triangular wave oscillator 9b, 105 Inverter 10 PWM modulator 10a, 107 First comparator 10b, 108 Second comparator 11 Drive circuit 11c, 111 First output circuit 11d, 112 Second output circuit 12, 15, 114 Drive system 12a, 15a, 114a Gain block 12b, 15b, 114b Modulation depth block 13a First voltage divider 13b Second voltage divider 14b Differential output amplifier 20, 21, 22 Drive block 23, 24, 25 Load 26, 27, 28 Power supply 29 Triangular wave center generator 113 Voltage-current converter IN_ Input terminal FO_ RO_ output terminal

Claims (9)

A first voltage-current converter for converting a command voltage into a current;
A voltage divider that divides the voltage between the output terminals;
A second voltage-current converter that converts the output voltage of the voltage divider to a current;
A capacitor having one end connected to a connection point between the output of the first voltage-current converter and the output of the second voltage-current converter;
An amplifier for amplifying the terminal voltage of the capacitor;
A triangular wave generator that generates triangular waves that are 180 degrees out of phase with each other;
A first comparator for comparing one of the triangular waves with reference to the output voltage of the amplifier;
A second comparator for comparing the output voltage of the amplifier with reference to the other triangular wave;
And a drive circuit for driving a load connected to an output terminal in accordance with the outputs of the first and second comparators.   The PWM drive device according to claim 1, wherein the triangular wave generator includes one triangular wave oscillator and an inverter.   The PWM drive device according to claim 1, wherein the triangular wave generator includes one triangular wave oscillator and a differential output amplifier.   The PWM drive device according to any one of claims 1 to 3, wherein the voltage divider includes a voltage divider circuit configured by two or more resistors. The voltage divider is composed of a first voltage divider and a second voltage divider provided for each output terminal,
5. The PWM drive device according to claim 1, wherein the second voltage-current converter converts a difference between output voltages of the first voltage divider and the second voltage divider into a current. 6.   The driving circuit includes first and second pre-drivers to which outputs of the first and second comparators are input, respectively, and two switching elements driven by the first and second pre-drivers, respectively. 6. The PWM drive according to claim 1, wherein an H-bridge type circuit is configured by the first and second output circuits and the load. apparatus.   The PWM drive device according to any one of claims 1 to 6, wherein the first and second voltage-to-current converters have the same transconductance. A plurality of PWM drive devices according to any one of claims 1 to 7,
A PWM driving device configured to share the triangular wave generator among a plurality of the PWM driving devices. A first voltage-current conversion step for converting a command voltage into a current;
A voltage dividing step for dividing the voltage between the output terminals;
A second voltage-current conversion step for converting the output voltage of the voltage division step into a current;
An integral voltage conversion step of storing the current output of the first voltage-current conversion step and the current output of the second voltage-current conversion step in a common capacitor and converting the voltage into a voltage;
An amplification step of amplifying the terminal voltage of the capacitor;
A triangular wave generating step for generating triangular waves that are 180 degrees out of phase with each other;
A first comparison step of comparing one triangular wave output from the triangular wave generation step with reference to the output voltage of the amplification step;
A second comparison step of comparing the output voltage of the amplification step with reference to the other triangular wave output from the triangular wave generation step;
And a drive step of driving a load connected to an output terminal in accordance with the outputs of the first and second comparison steps.

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