JP7353315B2 - Switching power supply device and current detection value conversion device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a switching power supply device and a detected current value converting device, which are equipped with a current balance circuit that makes the output current values of a plurality of switching power supply devices connected in parallel almost equal to each other.

Conventionally, as shown in FIG. 10, when using two switching power supplies 100A and 100B connected in parallel to a load 102, the output terminals +V and -V are connected in parallel and the current balance terminal CB is connected between them. The output voltages of the switching power supply devices 100A and 100B are controlled by a current balance circuit so that the output current values of the switching power supply devices 100A and 100B are approximately the same.

FIG. 11 shows a circuit of a conventional switching power supply device equipped with a current balance circuit. After the AC input voltage Vin is rectified and smoothed by an input rectifying and smoothing circuit 103, it is rectified and smoothed by the switching of an inverter circuit composed of an output transformer 104, an inverter element 105 using MOS-FET, a drive control circuit 106, and a rectifying and smoothing circuit 107. A constant output voltage Vout is supplied to the load from output terminals +V and -V.

The output terminals +V and -V are connected to sensing terminals +S and -S, and the output voltage Vout is input to the error detection circuit 108. The error detection circuit 108 causes an output current corresponding to the difference between the input voltage of a series circuit of resistors R116, R117, and R118 and a reference voltage VR to flow through a photocoupler light emitting element 113a connected in series with a resistor R119 using a differential amplifier 111 to emit light. It is driven and fed back to the input side by negative feedback 110.

The light from the photocoupler light emitting element 113a is received by the photocoupler light receiving element 113b built in the drive control circuit 106, and the inverter element 105 is controlled by switching so as to maintain the output voltage at a constant voltage.

The current balance circuit 109 includes a first current mirror circuit 115 made up of resistors R111, R112, R115, and transistors TR111, TR112, and a second current mirror circuit 116 made up of resistors R113, R114, and transistors TR113, TR114. .

The first current mirror circuit 115 receives a constant bias voltage VB from the bias voltage source 114. Further, a voltage (VB+V1) obtained by adding an output current detection voltage V1 proportional to the output current Iout detected from the inverter primary current Isw by the current transformer 112 to the bias voltage VB is applied to the second current mirror circuit 116. .

The current transformer 112 connects the primary winding to the primary side of the inverter, rectifies and smoothes the output of the secondary winding using diodes D111 and D112, a current detection resistor R120, and a capacitor C110, and extracts the output current detection voltage V1. ing.

The first current mirror circuit 115 causes a constant current IR to flow through the transistor TR111 by applying the bias voltage VB, and therefore, a constant current IR also flows to the other transistor TR112, and the transistor TR113 of the second current mirror circuit 116 is connected to the transistor TR112 side. It operates as a constant current source connected to the side.

The operation of the current balance circuit 109 is as follows. A constant current IR flows through the transistor TR113 of the second current mirror circuit 116 by the transistor TR112 of the first current mirror circuit 115, which functions as a constant current source. Further, a current balance voltage VCB is applied to the current balance terminal CB, which is lower than the output current detection voltage V1 proportional to the output current by the voltage drop of the resistor R113 and the transistor TR113 caused by the constant current IR.

Here, if the current balance voltage VCB of the current balance terminal of another switching power supply device connected to the current balance terminal CB is low, a current balance current IC corresponding to the difference between the two will flow, and as a result, the collector current of the transistor TR113 becomes (IR+IC). Therefore, the collector current of the other transistor TR114 also becomes (IR+IC), and the voltage generated across the resistor R118 increases in accordance with the current balance current IC.

As a result, the output of the differential amplifier 111 also increases, and the drive control circuit 106 controls the switching of the inverter element 105 to lower the output voltage Vout, thereby lowering the output current Iout and balancing the current.

Japanese Patent Application Publication No. 2013-150513

However, in a current balance circuit using such a conventional current transformer, component characteristics such as the inductance of the output transformer 104 are affected by the relationship between the primary side switch current Isw and the output current Iout, which are originally in a proportional relationship. Due to variations in the output current, a deviation occurs between devices, and therefore, the output current detection voltage V1, which is rectified and smoothed by transmitting the primary side switch current Isw to the secondary side by the isolated current transformer 112, and the output current Iout. There are also discrepancies in the relationship between devices.

Therefore, when connecting multiple switch power supplies in parallel, it is necessary to take this deviation into account. In other words, the deviation reduces the accuracy of current balance and reduces the allowable output current when connected in parallel. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a switching power supply device that enables highly accurate current balance operation by correcting variations in output current detection values for current balance control caused by variations inherent in the device such as components. .

Another object of the present invention is to provide a current detection value conversion device that enables highly accurate current monitoring by correcting variations in output current detection values caused by device-specific variations in components and the like.

(First invention: switching power supply device)
The present invention provides a current balance circuit that aligns the output current values of each switching power supply to almost the same value based on the output current detection value based on the switch current flowing in the primary side when the outputs of a plurality of switching power supply are connected in parallel. A switching power supply device comprising:
A first detected output current value detected corresponding to the switch current flowing to the primary side is converted into a second detected output current value according to predetermined conversion characteristics based on a pulse width modulation section using pulse width modulation conversion. Equipped with a current detection value conversion section that outputs the detected current value to the current balance circuit.
The present invention is characterized in that the conversion characteristics can be corrected by changing predetermined elements and maintaining the settings.

(Correction of conversion characteristics of output current detection value)
The conversion characteristic of the current detection value conversion section is a conversion characteristic of a predetermined linear function,
The predetermined element is an element for determining the pulse period of pulse width modulation conversion and/or a bias value added to the first output current detection value input to the pulse width modulation section,
By changing the elements for determining the pulse period and holding the settings, the slope of the linear function is corrected, and by changing the bias value and holding the settings, the intercept of the linear function is corrected.

(Pulse modulation section)
The pulse width modulation section is
a current detection value input section that detects and inputs a first output current detection value by dividing, rectifying and smoothing the switch current flowing to the primary side;
a reset section that outputs a reset signal at a predetermined cycle;
a triangular wave generator that repeatedly generates a triangular wave signal at a period based on a reset signal;
a comparator that inputs and compares the first output current detection value and the triangular wave signal to perform pulse width modulation conversion and output a pulse width modulation signal;
After inputting the pulse width modulation signal to the set terminal, inputting the reset signal to the reset terminal, and outputting the inverted pulse width modulation signal from the inversion output terminal and supplying it to the triangular wave generator to stop the generation of the triangular wave signal. A set-reset type flip-flop that generates the signal again,
a signal transmission section that electrically separates the inverted pulse width modulation signal output from the inverted output terminal by optical coupling of a photocoupler and transmits it to the secondary side;
a current detection value output unit that generates a second output current detection value by smoothing the inverted pulse width modulation signal transmitted by the signal transmission unit and outputs the second output current detection value to the current balance circuit;
Equipped with
By changing the period of the reset signal output from the reset section and maintaining the setting, and changing the period of the pulse width modulation signal, the slope of the linear function is corrected, and the first output current detection value input to the comparator is By changing the bias value and maintaining the setting, the intercept of the linear function is corrected.

(Second invention: current detection value conversion device)
The present invention is a current detection value conversion device, comprising:
A current detection value conversion device that converts an inputted first output current detection value into a second output current detection value according to predetermined conversion characteristics based on a pulse width modulation section using pulse width modulation conversion, and outputs the second output current detection value. ,
The present invention is characterized in that the conversion characteristics can be corrected by changing predetermined elements and maintaining the settings.

(Correction of conversion characteristics of output current detection value)
The conversion characteristic is a conversion characteristic according to a predetermined linear function,
The predetermined element is an element for determining the pulse period of pulse width modulation conversion and/or a bias value added to the first output current detection value input to the pulse width modulation section,
By changing the elements for determining the pulse period and holding the settings, the slope of the linear function is corrected, and by changing the bias value and holding the settings, the intercept of the linear function is corrected.

(Pulse modulation section)
The pulse width modulation section is
a current detection value input unit that detects and inputs a first output current detection value from a predetermined current flowing through a predetermined target device;
a reset section that outputs a reset signal at a predetermined cycle;
a triangular wave generator that repeatedly generates a triangular wave signal at a period based on a reset signal;
a comparator that inputs and compares the first output current detection value and the triangular wave signal to perform pulse width modulation conversion and output a pulse width modulation signal;
After inputting the pulse width modulation signal to the set terminal, inputting the reset signal to the reset terminal, and outputting the inverted pulse width modulation signal from the inversion output terminal and supplying it to the triangular wave generator to stop the generation of the triangular wave signal. A set-reset type flip-flop that generates the signal again,
a current detection value output unit that generates and outputs a second output current detection value by smoothing the inverted pulse width modulation signal;
Equipped with
By changing the period of the reset signal output from the reset section and maintaining the setting, and changing the period of the pulse width modulation signal, the slope of the linear function is corrected, and the first output current detection value input to the comparator is By changing the bias value and maintaining the setting, the intercept of the linear function is corrected.

(Photocoupler signal transmission part)
The pulse width modulation section further includes a signal transmission section that electrically separates the inverted pulse width modulation signal output from the inversion output terminal of the flip-flop by optical coupling of a photocoupler and transmits it to the current detection value output section. Be prepared.

(First invention: Effects of switching power supply device)
According to the switching power supply device of the present invention, even if there is device-specific variation in the detected current value of the primary switch current used for current balance control due to variations caused by device components such as the inductance value of the output transformer. , a first output current detection value detected corresponding to the switch current flowing in the primary side is converted into a second output current detection value according to a predetermined conversion characteristic based on the pulse width modulation section, and the current balance circuit The conversion characteristics are corrected by changing a predetermined element of the pulse width modulation section, and the variation in the second output current detection value converted from the first output current detection value, which varies from device to device, is reduced and specified. By enabling highly accurate current balance operation, it is possible to reduce the degree of reduction in allowable output current when a plurality of switching power supply devices are connected in parallel to a load.

(Effects due to correction of conversion characteristics of output current detection value)
In addition, since the conversion characteristics of the current detection value conversion section are those of a predetermined linear function, the slope of the linear function is corrected by changing the pulse period of the pulse width modulation section. By changing the bias value of the first output current detection value to be input, the intercept of the linear function is corrected, and this eliminates variations in the first output current detection value due to components in the switching power supply connected in parallel. Even if there is, by correcting the conversion characteristics by changing the pulse period and/or bias value, it is possible to appropriately align the second output current detection values that are converted and output.

Correction of this conversion characteristic is performed in the process after manufacturing the switching power supply by using a special adjustment device such as a personal computer, which adjusts the first output voltage detection value and the second current detection value while changing the output current. Measure the values, plot the conversion characteristics of the linear function, correct the pulse period and bias value so that they become the reference characteristics, and after correction, set the pulse period and bias value on the switching power supply side. By storing it as , the conversion characteristics can be easily and easily corrected.

(Effect of pulse modulation section)
The pulse width modulation section includes a current detection value input section using a rectifying and smoothing circuit, a reset section, a triangular wave generator, a comparator, a set-reset type flip-flop, a photocoupler signal transmission section, and a smoothing circuit. Since it is based on a known pulse width modulation circuit equipped with a current detection value output section, it can be simply and easily configured, and the conversion characteristic of the linear function is based on the period of the reset signal, that is, the pulse width modulation signal. By changing the pulse period and storing the settings, the slope of the linear function is corrected, and by changing the bias value of the first output current detection value input to the comparator and storing the settings, the linear function The intercept can be corrected. Furthermore, signals can be transmitted from the primary side to the secondary side using an inexpensive photocoupler without using a current transformer.

(Second invention: Effects of current detection value conversion device)
The present invention is not limited to a switching power supply device equipped with a current balance circuit, but can be used, for example, as a current detection value conversion device for monitoring a current flowing in an arbitrary target device or performing a predetermined control based on the current. Even if the current varies from device to device due to variations in the components of the target device, the first output current detection value detected from the current flowing through the target device is is converted into a second output current detection value according to a predetermined conversion characteristic based on the current value and outputted for monitoring or control, and the conversion characteristic is corrected by changing a predetermined element of the pulse width modulation section, and the first output current is It is possible to reduce variations in the second output current detection value converted from the current detection value between devices and keep it within the specified range, enabling highly accurate current monitoring and current-based control even if the target devices are different. This makes it possible to maintain the performance and quality of the target device at a high level.

Furthermore, the "effects of correcting the conversion characteristics of the detected output current value" and the "effects of the pulse modulation section" are basically the same as in the case of the switching power supply device described above.

In addition, unlike switching power supplies, current detection value converters do not necessarily require isolation between the primary and secondary sides, so the "photocoupler transmission section" is not included in the pulse width modulation section. This makes the configuration simpler. On the other hand, if the target device is insulated and separated into the primary side and the secondary side, and the conversion result is used on the secondary side, the pulse width modulation section should be connected to the photocoupler transmission section, similar to a switching power supply. ”.

1 is a circuit block diagram showing an embodiment of a switching power supply device of the present invention connected in parallel; FIG. FIG. 2 is a circuit block diagram showing an embodiment of the current detection value conversion section of FIG. 1. FIG. 3 is a time chart showing signal waveforms of each part of the current detection value converter shown in FIG. 2. FIG. 4 is a graph section showing conversion characteristics of the first output current detection value V1 and the second output current detection value V2 by the current detection value conversion section of FIG. 3; 3 is a time chart showing signal waveforms of various parts when the pulse period is changed in the current detection value converter shown in FIG. 2. FIG. 6 is a graph section showing a change in the conversion characteristics of the first output current detection value V1 and the second output current detection value V2 by the current detection value conversion section as the pulse period of FIG. 5 is changed; 3 is a time chart showing signal waveforms at various parts when the bias value is changed in the current detection value converter shown in FIG. 2; 8 is a graph section showing a change in the conversion characteristics of the first output current detection value V1 and the second output current detection value V2 by the current detection value conversion section as the bias value of FIG . 7 is changed; 1 is a block diagram showing an embodiment of a current detection value conversion device according to the present invention. FIG. 2 is an explanatory diagram showing switching power supply devices that are connected in parallel and used. FIG. 1 is a circuit block diagram showing a conventional switching power supply device including a current balance circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a switching power supply device and a current detection value conversion device according to the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following embodiments.

[Basic concept of embodiment]
First, the basic concept of the embodiment will be explained. The embodiment according to the first invention of the present application generally relates to a switching power supply device including a current balance circuit.

Here, a "switching power supply" refers to a switching element that converts input power on the primary side into a specified DC power to be used on the secondary side, and uses a switching element to maintain a constant output voltage through feedback control. It is a control device equipped with a current balance circuit, and includes a switching stabilized power supply, a switching regulator, etc., and the concept includes an AC-DC converter, a DC-DC converter, etc.

Furthermore, "switching power supplies" are divided into non-insulated types and isolated types, but this embodiment takes as an example an isolated DC-DC converter that transmits power from the primary side to the secondary side by transformer coupling. The circuit methods include LLC resonance method, forward method, flyback method, half bridge method, full bridge method, etc.

Furthermore, a "current balance circuit" is a circuit that controls switching elements so that when multiple switching power supplies are connected in parallel to a load, the output current values of each switching power supply are approximately the same. This concept includes circuits using current mirror circuits.

The switching power supply device also includes a current detection value conversion section. "Current detection value conversion unit" is a device that converts the first output current detection value detected corresponding to the switch current flowing in the primary side into a predetermined conversion characteristic based on a pulse width modulation unit using pulse width modulation conversion. The second output current detection value is converted into a second output current detection value and output to the current balance circuit, and the conversion characteristics can be corrected by changing predetermined elements and holding the settings (setting memory). .

Here, the "first output current detection value" is a "first output current detection voltage" that is a detection voltage detected by dividing, rectifying and smoothing the switch current flowing to the primary side, for example. Conventionally, the current detection value is output as is to the current balance circuit, but in this embodiment, the current detection value converter converts it into a second output current detection value according to predetermined conversion characteristics, and then outputs it to the current balance circuit. This is what is output.

Furthermore, the "pulse width modulation unit" is a unit that converts the inputted first output current detection value into a pulse width modulation signal having a pulse width corresponding to the pulse width and outputs the signal, and uses PWM (Pulse Width Modulation). It is. Here, the pulse width is the time during which the pulse signal is at the H level within the pulse, and can also be expressed as the duty (also called on-duty or duty ratio), which is the pulse width divided by the pulse period. In this case, it can also be said that the "pulse width modulation section" converts into a pulse width modulation signal having a duty corresponding to the inputted first output current detection value and outputs the signal.

The pulse width modulation section is well known, and its configuration and function are arbitrary. It inputs a triangular wave signal and outputs a pulse width modulated signal.

Furthermore, "predetermined conversion characteristics" refers to characteristics for converting the first detected output current value into a pulse width (duty) and characteristics for converting the converted pulse width (duty) into a second detected output current value. In this embodiment, the first output current detection value is the first output current detection voltage V1, and the second output current detection value is the second output current detection voltage V2. Ori,
V2=aV1+b
The conversion characteristic follows a linear function of . Here, a is the slope of the linear function, and b is the intercept of the linear function.

In addition, the switching power supply device of this embodiment can change predetermined elements and maintain the settings so that V2=aV1+b
It is configured to be able to correct the conversion characteristics of.

Here, the "predetermined element" includes an element for determining the pulse period of pulse width modulation conversion and a bias value added to the first output current detection value input to the pulse width modulation section. When the element for determining the pulse period of pulse width modulation conversion is changed to change the pulse period of the pulse width modulation section, the slope a in the conversion characteristic of the linear function is corrected. Furthermore, when the bias value is changed, the intercept b in the conversion characteristic of the linear function is corrected. By correcting the conversion characteristics of the pulse width modulation section, the second output current detection value output from the current detection value conversion section can be adjusted to an appropriate value.

Although the switch current flowing through the primary side of a switching power supply device and the output current from the secondary side have a predetermined relationship, deviations occur from device to device due to variations in components such as the inductance value of the output transformer. Therefore, the first output current detection value, which is obtained by dividing the switch current flowing to the primary side and rectifying and smoothing it, also varies from device to device in relation to the output current due to component variations, and the current balance remains unchanged. When used for operation, the accuracy of current balance to match the output current of other switching power supply devices connected in parallel decreases.

Therefore, in the present embodiment, in a process after the manufacturing of the switching power supply device is completed, the first output current detection value and the second output current detection value of the pulse width modulation section are changed to the output current to the load. For example, the conversion characteristics of a linear function are obtained by measuring while changing the characteristics, and the correction is performed so that the conversion characteristics of the obtained linear function match the conversion characteristics of a linear function that is a predetermined standard. The optimum pulse period and bias value are obtained using the pulse width modulation section of the switching power supply device, and the settings are held in the pulse width modulation section of the switching power supply device.

As a result, even if there is a deviation between the primary side switch current and the output current of a manufactured switching device due to variations in components, the second output current detection value used for current balance control can be adjusted for each device. The deviation is reduced and eliminated, and a highly accurate current balance operation is performed when the switching power supply device is connected in parallel to the load.

Further, the current detection value converting device according to the second invention of the present application is not limited to a switching power supply device equipped with a current balance circuit, but is capable of converting the input first output current detection value using pulse width modulation conversion. It converts into a second output current detection value and outputs it according to a predetermined conversion characteristic based on the pulse width modulation section, and as in the case of a switching power supply, it includes elements for determining the pulse period of pulse width modulation conversion, for example. By changing the bias value, the slope and intercept of the conversion characteristic are corrected according to the linear function, and even if there is a deviation due to device-specific variations, the conversion characteristic of the linear function based on the second output current detection value is corrected. In accordance with this, for example, the accuracy of monitoring the second output current detection value or performing predetermined control based on the second output current detection value is improved.

Hereinafter, specific embodiments will be described. In the specific embodiment shown below, the "switching power supply" is an "LLC resonance type switching power supply", and the "first output current detection value" is the "first output current detection voltage V1". A case will be described in which the "second output current detection value" is the "second output current detection voltage V2".

[Specific embodiment of switching power supply device]
The specific contents of the embodiment of the switching power supply device will be described in more detail. The contents will be explained separately as follows.

a. Switching power supply device connected in parallel a1. Switching power supply 10A
a2. LLC resonant converter a3. Current balance circuit 32
b. Current detection value converter 30
b1. Current detection value input section 46
b2. Pulse width modulation section 38
b2-1. Triangle wave generator 50
b2-2. Comparator 48
b2-3. Reset section 54
b2-4. RS-FF52
b3. Photo coupler 58
b4. Current detection value output section 60
b5. Bias section 64
c. Correction of conversion characteristics of current detection value conversion section c1. Operation and conversion characteristics of current detection value converter 30 c2. V1-V2 conversion characteristics d. Correction of V1-V2 conversion characteristics by changing pulse period e. Correction of V1-V2 conversion characteristics by changing bias voltage valuef. Adjustment of switching power supply g. Current detection value converter h. Modifications of the present invention

[a. Switching power supply connected in parallel]
First, a switching power supply device including a current balance circuit will be described in more detail. FIG. 1 is a circuit block diagram showing an embodiment of two LLC resonance type switching power supply devices. As shown in FIG. 1, when using two switching power supplies 10A and 10B connected in parallel to the load 26, the output terminals 24a and 24b are connected in parallel, and the current balance terminal 25 is connected, The current balance circuit 32 controls the output voltage Vout of each of the switching power supply devices 10A and 10B so that the output current value Iout of each of the switching power supply devices 10A and 10B is equalized to substantially the same value.

(a1. Switching power supply device 10A)
To explain the switching power supply device 10A (the same applies to the switching power supply device 10B), the AC input voltage Vin is rectified and smoothed by the input rectification and smoothing circuit 14, and then the output transformer 20, the switching element 15 using MOS-FET, 16, a drive control section 18, and a rectifying and smoothing circuit 22. By switching an LLC resonant converter, a constant output voltage Vout is supplied to the load 26 from output terminals 24a and 24b. Here, although the rectifying and smoothing circuit 22 on the secondary side is arbitrary, it is, for example, a voltage doubler rectifying and smoothing circuit using a secondary winding L2 having a center tap.

(a2.LLC resonant converter)
The LLC resonant converter takes a half-bridge type as an example, and is composed of a series circuit of switching elements 15 and 16, a resonant capacitor C1, an output transformer 20, and a rectifying and smoothing circuit 22. The output transformer 20 has a primary winding L1 and a secondary winding L2, and by reducing the coupling coefficient, the equivalent leakage inductance Lr is increased, and this is used as a resonant inductor. Furthermore, an exciting inductance Lm is equivalently connected in parallel to the primary winding L1.

The outline of the operation of the LLC resonant converter is as follows. The drive control unit 18 turns on and off the switching elements 15 and 16 alternately at a predetermined switching frequency. When the switching element 15 is turned on while the switching element 16 is off, the current flows in the positive direction along a path that connects the power supply positive 12a side, the leakage inductance Lr, the primary winding L1 and the exciting inductance Lm, the resonance capacitor C1, and the power supply negative 12b side. Resonant current flows.

As the resonant capacitor C1 is charged, the resonant current in the positive direction decreases, and the switching element 15 is activated at the timing when the current flowing through one of the rectifier diodes of the voltage doubler rectifier circuit that constitutes the rectifier and smoothing circuit 22 on the secondary side approaches zero. Zero voltage switching (ZVC) is performed in which the switching element 16 is turned off and then turned on. As a result, the electrical energy stored in the resonant capacitor C1 causes a resonant current to flow in the negative direction through the switching element 16, the primary winding L1, the exciting inductance Lm, the leakage inductance Lr, and the resonant capacitor C1.

The resonant current in the negative direction decreases due to the discharge of the resonant capacitor C1, and the switching element 16 is turned off at the timing when the current flowing through the other rectifier diode of the voltage doubler rectifier circuit that constitutes the rectifier and smoothing circuit 22 on the secondary side approaches zero. Then, zero voltage switching (ZVC) is performed to turn on the switching element 15, and this process is repeated. Note that the details of the zero voltage switching (ZVC) operation of the switching elements 15 and 16 are well known and are omitted here.

Further, the LLC resonant converter is a circuit system that controls the output voltage Vout by frequency modulation. Regarding the relationship between the switching frequency and the input/output voltage ratio of the LCC resonant converter, the operation mode differs around the maximum value of the input/output voltage ratio as a boundary, and the LCC resonant converter is used in a frequency region where the input/output voltage ratio is higher than the maximum value. In this frequency range, the input/output voltage ratio decreases as the switching frequency increases. That is, by increasing the switching frequency in the drive control section 18, the output voltage Vout can be decreased, and by decreasing the switching frequency, the output voltage Vout can be increased.

The output voltage Vout is input to the error detection section 28. The error detection unit 28 outputs an output current corresponding to the difference between the voltage obtained by dividing the output voltage Vout by a series circuit of resistors R3 and R4 and the reference voltage VR of the reference voltage source 36 to the photocoupler light emitting element 40a using the differential amplifier 34. Flow and drive the light emission.

The light from the photocoupler light emitting element 40a is received by the photocoupler light receiving element 40b built into the drive control section 18, and the switching frequencies of the switching elements 15 and 16 are controlled so as to maintain the output voltage at a constant voltage. The drive control unit 18 is, for example, a computer circuit equipped with a CPU such as a microprocessor, memory, various input/output ports, etc., and the functions of the drive control unit 18 are realized by executing a program.

(a3. Current balance circuit 32)
The current balance circuit 32 includes a current mirror circuit composed of resistors R1, R2 and transistors TR1, TR2, and the collector of the transistor TR1 is connected in series to a constant current source 42 and a bias power source 44 having a bias voltage VB.

The current detection value converter 30 detects a first output current detection voltage V1 by dividing, rectifying and smoothing the switch current flowing through the resonant capacitor C1, and then detects the first output current detection voltage V1 by performing pulse width modulation and smoothing. 2 output current detection voltage V2 is applied to the current mirror circuit of the current balance circuit 32.

Therefore, a voltage (VB+V2) obtained by adding a second output current detection voltage V2 proportional to the output current Iout from the current detection value converter 30 to the bias voltage VB is applied to the current mirror circuit.

The operation of the current balance circuit 32 is as follows. A constant current source 42 causes a constant current IR to flow through the transistor TR1 of the current mirror circuit. Further, a current balance voltage VCB is applied to the current balance terminal 25, which is lower than the second output current detection voltage V2 proportional to the output current by the voltage drop across the resistor R1 and the transistor TR1 due to the constant current IR.

Here, if the current balance voltage VCB of the current balance terminal 25 of another switching power supply device 10B connected to the current balance terminal 25 is low, a current balance current IC corresponding to the difference between the two flows, and therefore The collector current is (IR+IC). Therefore, the collector current of the other transistor TR2 also becomes (IR+IC), and the voltage generated across the resistor R4 increases in accordance with the current balance current IC.

As a result, the output of the differential amplifier 34 also increases, and the drive control unit 18 controls the output voltage Vout to decrease by increasing the switching frequency of the switching elements 15 and 16, so that the output current Iout decreases and the current balance You will begin to take .

On the other hand, the collector current of the transistor TR2 of the current balance circuit 32 in the other switching power supply device 10B becomes (IR-IC), and the voltage generated across the resistor R4 decreases. As a result, the output of the differential amplifier 34 also decreases, and the drive control unit 18 controls to increase the output voltage Vout by lowering the switching frequency of the switching elements 15 and 16, so that the output current Iout increases and the current balance You will begin to take .

[b. Current detection value conversion unit 30]
Next, the detected current value converter 30 shown in FIG. 1 will be explained in more detail. The current detection value converter 30 performs pulse width modulation on a first output current detection voltage V1 detected corresponding to a resonant current that becomes a switch current flowing to the primary side when the switching elements 15 and 16 are turned on and off. The second output current detection voltage V2 is converted into a second output current detection voltage V2 according to a predetermined conversion characteristic based on the pulse width modulation section 38 and applied to the current mirror circuit of the current balance circuit 32. In particular, the pulse period T in the pulse width modulation section 38 is inputted. By changing the bias value Vb of the first output current detection voltage V1 and storing the setting, a conversion characteristic (hereinafter referred to as "V1-V2 It is characterized by being configured to be able to correct the conversion characteristics (referred to as "conversion characteristics").

FIG. 2 is a circuit block showing an embodiment of the current detection value converter. As shown in FIG. 50, an RS-FF (set/reset type flip-flop) 52, a reset section 54, a photocoupler 58, a detected current value output section 60, and a bias section 64. Of these, the pulse width modulation section 38 includes a comparator 48, a triangular wave generator 50, an RS-FF 52, and a reset section 54.

(b1. Current detection value input section 46)
The current detection value input section 46 will be explained in more detail. The current detection value input section 46 is composed of, for example, capacitors C2, C3, C4, diodes D1, D2, and resistors R5, R6. That is, a series circuit of capacitors C2 and C3 is connected between the primary winding L1 and the resonant capacitor C1, a cathode of the anode diode D2 of the diode D1 is connected between the capacitors C2 and C3, and a capacitor is connected to the cathode of the diode D2. One end of C4 is connected to a series circuit of resistors R5 and R6, and a first output current detection voltage V1 is taken out between resistors R5 and R6.

The current detection value input section 46 divides the current flowing through the resonant capacitor C1 with capacitors C3 and C4, rectifies it with diodes D1 and D2, smooths it with capacitor C4, divides it with resistors R5 and R6, and divides the current into the primary A first output current detection voltage V1 proportional to the resonant current (switch current) flowing to the side is detected.

(b2. Pulse width modulation section 38)
The pulse width modulation section 38 will be explained in more detail. The pulse width modulation section 38 is composed of a triangular wave generator 50, a comparator 48, an RS-FF 52, and a reset section 54.

(b2-1. Triangular wave generator 50)
The triangular wave generator 50 will be explained in more detail. The triangular wave generator 50 generates a triangular wave that increases linearly over time with a predetermined pulse period T, and although its configuration and function are arbitrary, as an example, it includes a constant current source 62 and a capacitor. It consists of a C5 series circuit. The capacitor C5 is discharged and reset at every predetermined pulse period, and when the discharge reset is released, the capacitor C5 is charged with a constant current from the constant current source 62, and the capacitor increases linearly with the passage of time. The charging voltage is output to the comparator 48 as a triangular wave signal (triangular wave voltage) Vt.

(b2-2. Comparator 48)
Comparator 48 will be explained in more detail. The comparator 48 inputs the first output current detection voltage V1 from the current detection value input section 46 to the positive input terminal, inputs the triangular wave signal (triangular wave voltage) Vt from the triangular wave generator 50 to the negative input terminal, By comparing the two, a pulse width modulation signal is output.

That is, in the pulse period T, when the triangular wave signal Vt, which increases over time, is smaller than the first output current detection voltage V1, the output of the comparator 48 becomes H level, and the triangular wave signal Vt becomes the first output current. When the detection voltage V1 is reached, the output of the comparator 48 switches to the L level, and outputs a pulse width modulation signal with a pulse width proportional to the magnitude of the first output current detection voltage V1. Here, the ratio of the pulse width to the pulse period of the pulse width modulation signal is the duty, and the comparator 48 outputs the pulse width modulation signal with the duty proportional to the magnitude of the first output current detection voltage V1. .

(b2-3. Reset section 54)
The reset unit 54 will be explained in more detail. The reset unit 54 outputs a reset pulse Vr at a predetermined period that determines the pulse period T of the pulse width modulation signal, and its configuration and function may be arbitrary. For example, the function of the drive control unit 18 in FIG. This is realized by the pulse generation function 56 realized by executing a program of a computer circuit such as a microprocessor. That is, the pulse generation function 56 of the reset section 54 generates a reset pulse Vr of a predetermined pulse width every cycle based on the pulse cycle setting value stored in the pulse cycle setting section 57, which is realized as a memory storage function. , is output to the reset terminal R of the RS-FF52.

(b2-4.RS-FF52)
The RS-FF52 will be explained in more detail. As is well known, the RS-FF52 has a set input S, a reset input R, a non-inverted output Q, and an inverted output Qbar, and the relationship between the input (RS) and the output (QQbar) is as follows.
(L L) (hold)
(HL) at (HL)
(L H) at (L H)
(H H) (prohibited)
becomes. Note that the inverted output Qbar is indicated in the drawing by a symbol with a horizontal bar placed above Q, as is well known.

In this embodiment, the output of the comparator 48 becomes the set input S of the RS-FF 52, the output of the reset section 56 (reset pulse Vr) becomes the reset input R of the RS-FF 52, and the Qbar output is sent to the next stage photocoupler 58. Since the pulse width modulation signal is output from the comparator 48, it is inverted by the RS-FF 52 and output to the photocoupler 58.

Further, the Qbar output of the RS-FF 52 is connected between the constant current source 62 of the triangular wave generator 50 and the capacitor C5 via a diode D3. Therefore, the triangular wave signal Vt reaches the first output current detection voltage V1 in the comparator 48, the output of the comparator 48 rises from the L level to the H level, and the Qbar output of the RS-FF 52 falls to the L level. , the capacitor C5 of the triangular wave generator 50 is discharged and reset via the diode D3, and the triangular wave signal Vt is stopped. Next, when the reset pulse Vr is output, the Qbar output rises to H level due to the reset of the RS-FF 52, and the diode D3 is turned off by reverse bias, and the constant current source 62 of the triangular wave generator 50 charges the capacitor C5. By restarting, generation of a new triangular wave signal Vt is started.

(b3. Photocoupler 58)
The photocoupler 58 will be explained in more detail. The photocoupler 58 functions as a signal transmission section that electrically insulates and separates the primary side and the secondary side of the current detection value conversion section 30, and converts an electrical signal into an optical signal, transmits it, and then converts it back into an electrical signal. Its configuration and type are arbitrary, but for example, it is equipped with a light emitting diode 58a and a phototransistor 58b, each of which is connected in pull-up to the power supply line by resistors R9 and R10, and the pulse inverted by the RS-FF52. The width modulation signal drives the light emitting diode 58a to emit light, and the phototransistor 58b receives the light, converts it into a pulse width modulation signal Vpwm, and outputs it to the current detection value output section 60.

(b4. Current detection value output section 60)
The current detection value output section 60 will be explained in more detail. The current detection value output unit 60 is a smoothing circuit in which a resistor R11 and a capacitor C7 are connected in series, and outputs the charging voltage of the capacitor C7, which is obtained by smoothing the pulse width modulation signal Vpmw output from the photocoupler 58, to the second output current detection. The voltage V2 is applied to the current mirror circuit of the current balance circuit 32 shown in FIG.

(b5. Bias section 64)
The bias section 64 will be explained in more detail. The bias section 64 includes a bias value setting section 68, a duty pulse generation function 66, resistors R7 and R8, and a capacitor C6. The duty pulse generation function 66 is realized, for example, by executing a program of a computer circuit such as a microprocessor that realizes the function of the drive control unit 18 in FIG. A pulse signal having a set duty is generated at a predetermined period in a section 68.

Resistor R7 and capacitor C6 constitute a smoothing circuit, which smooths the duty pulse output from duty pulse generation function 66 to generate a smoothed voltage corresponding to the duty, outputs bias voltage Vb via resistor R8, and current It is added to the first output current detection voltage V1 output from the detection value input section 46 and outputs (V1+Vb) to the comparator 48.

[c. Correction of conversion characteristics of current detection value conversion section]
The conversion characteristic based on the PWM modulation circuit section 38 for converting the first output current detection voltage V1 to the second output current detection voltage V2 in the current detection value conversion section 30 is a conversion characteristic of a predetermined linear function,
V2=a・V1+b
is given by Here, a is the slope of the graph of the linear function, and b is the intercept on the V2 axis.

(c1. Operation and conversion characteristics of current detected value converter 30)
The operation of the current detection value conversion section 30 in FIG. 2 when the bias voltage Vb is set to zero in the bias section 64 will be explained as follows with reference to the time chart showing the signal waveforms of each section in FIG.

As shown in FIG. 3(A), the comparator 48 receives the first output current detection voltage V1 and the triangular wave signal Vt, and outputs the triangular wave signal at a pulse period T1 determined by the reset pulse Vr shown in FIG. 3(B). The occurrence of Vt is repeated. The triangular wave signal Vt starts to increase in synchronization with the rising of the reset pulse Vr to the H level, and when it is smaller than the first output current detection voltage V1, the output of the comparator 48 is at the L level, and as shown in FIG. 3(D). The Qbar output of the RS-FF 52 shown is at H level.

When the triangular wave signal Vt reaches and matches the first output current detection voltage V1, the output of the comparator 48 rises to the H level, and the Qbar output of the RS-FF 52 falls to the L level. Therefore, the Qbar output of the RS-FF 52 becomes a pulse width modulated signal with a pulse width (duty) proportional to the voltages at points a, b, and c of the first output current detection voltage V1. The pulse width modulation signal from Qbar of the RS-FF 52 is transmitted to the current detection value output section 60 on the secondary side via the photocoupler 58, and is smoothed to produce a second output current corresponding to the pulse width (duty). It is converted into a detection voltage V2 and output to the current balance circuit 32.

(c2.V1-V2 conversion characteristics)
FIG. 4 shows the conversion characteristic of the current detection value conversion section 30 corresponding to the operation according to the time chart of FIG. 3, that is, the V1-V2 conversion characteristic 70,
V2=a・V1+b
The conversion characteristic follows a predetermined linear function shown by .

Here, the switch current on the primary side of the switching power supply devices 10A and 10B is proportional to the output current Iout, but deviations inherent to the devices occur due to variations in the inductance value of the output transformer 20, etc. Therefore, the V1-V2 characteristic of the current detection value converter 30 shown in FIG. 4 also becomes different depending on the deviation of the primary side switch current. Therefore, in this embodiment, even if there is a deviation in the primary side switching current proportional to the output current Iout for each switching power supply device, the current value converter 30 adjusts V1- to eliminate this deviation. This is to correct the V2 conversion characteristics.

[d. Correction of V1-V2 conversion characteristics by changing pulse period]
The slope a of the linear function in the V1-V2 conversion characteristic of the current detection value converter 30 can be corrected by changing the pulse period T of the pulse width modulator 38.

FIG. 5 shows signal waveforms of various parts when the pulse period of the reset pulse Vr output from the reset section 54 is changed to a pulse period T2 longer than the pulse period T1 of FIG. When the pulse period T2 is changed to a longer pulse period T2 in this way, as shown in the graph of the V1-V2 conversion characteristics in FIG. The characteristic 72 can be corrected to increase the slope a of the linear function. On the other hand, by changing the pulse period to a shorter period, correction can be made to reduce the slope a of the linear function.

[e. Correction of V1-V2 conversion characteristics by changing bias voltage value]
The intercept b of the linear function in the V1-V2 conversion characteristic of the current detection value conversion section 30 can be corrected by changing the bias voltage Vb by the bias section 64.

FIG. 7 shows signal waveforms at each section when the bias voltage VB is output from the bias section 64 and (V1+Vb) is inputted to the comparator 48 . When the bias voltage Vb is added and the first output current detection voltage V1 is changed to an increased value, the V1-V2 conversion characteristic without the bias voltage Vb is changed as shown in the graph of the V1-V2 conversion characteristic in FIG. 70, the V1-V2 conversion characteristic 74 when the bias voltage Vb is applied can be corrected by increasing the intercept b of the linear function to the intercept b1. Of course, by reducing the bias voltage VB, correction can be made to reduce the intercept b1 of the linear function.

[f. Adjustment of switching power supply]
In the switching power supply device of this embodiment, during the inspection process after the manufacturing is completed, the first output current detection voltage of the current detection value converter is changed while changing the output current Iout for each device. Measure V1 and the second output current detection voltage V2, create a graph of the V1-V2 conversion characteristic shown in Figure 4, and make it match the predetermined reference V1-V2 conversion characteristic or minimize the deviation. , the pulse period setting section 57 changes the pulse period to correct the slope a in the V1-V2 conversion characteristic, and the bias value setting section 68 changes the bias value to correct the intercept b in the V1-V2 conversion characteristic. The operation will be performed. Here, the pulse period setting section 57 and the bias value setting section 68 are realized by storing each setting value in memory, and when the correction operation is completed, the changed pulse period and bias value stored in the memory are realized. The value-based pulse width modulation results in a conversion according to the reference V1-V2 conversion characteristic.

In this way, the correction work to adjust the V1-V2 conversion characteristic to the reference V1-V2 conversion characteristic can be carried out by preparing a dedicated adjustment device using a personal computer, etc., and changing the output current Iout while changing the output current Iout. Measure the first output current detection voltage V1 and the second output current detection voltage V2, display the V1-V2 conversion characteristics as a graph on the display, and enter each setting value of the pulse period setting section 57 and bias value setting section 68 using the keyboard or the like. After the correction is completed, each set value is stored in the memory of the microprocessor provided in the switching power supply.

[g. Current detection value conversion device]
An embodiment of the current detection value conversion device according to the second invention of the present application will be described in more detail. FIG. 9 is a block diagram showing an embodiment of a current detection value conversion device 80. As an example, the current detection value conversion device 80 includes a current detection value input section 46, a comparator 48, a triangular wave generator 50, an RS-FF 52 , a reset section 54, a pulse period setting section 57, a photocoupler 58, a detected current value output section 60, a bias section 64, and a bias value setting section 68. Of these, the pulse width modulation section 38 includes a comparator 48, a triangular wave generator 50, an RS-FF 52, and a reset section 54.

The current detection value conversion device 80 of the present embodiment converts a first output current detection voltage V1 detected corresponding to a switch current flowing through the primary side of an arbitrary target device into a predetermined output current detection voltage V1 based on the pulse width modulation unit 38. It converts into a second output current detection voltage V2 according to the conversion characteristics and outputs it, for example, as a current monitor value or a control current value, and in particular, the pulse period in the pulse width modulation section 38 and the input first output current detection voltage By changing the bias value of V1 and storing the setting, it is possible to correct the V1-V2 conversion characteristic for converting the first output current detection voltage V1 to the second output current detection voltage V2.

Also, a current detection value input section 46, a comparator 48, a triangular wave generator 50, an RS-FF 52, a reset section 54, a pulse period setting section 57, a photocoupler 58, a current detection value output section 60, a bias section 64, and a bias value setting section. The details of the section 68 are the same as those shown as the current detection value converting section 30 in FIG. 2, so the explanation will be omitted. Furthermore, if the target device does not require insulation and separation between the primary side and the secondary side, the photocoupler 58 functioning as a signal transmission section is not required.

According to the current detection value conversion device 80, even if the current varies from device to device due to variations in components of the target device, the first output current detected from the current flowing through the target device The value V1 is converted into a second output current detection value V2 according to a predetermined conversion characteristic based on the pulse width modulation section 38 and output for monitoring or control, and the pulse period of the pulse width modulation section 38 and/or the first By changing the bias voltage Vb added to the output current detection voltage V1, the slope and intercept in the conversion characteristic according to the linear function are corrected, and the second output current detection value is converted from the first output current detection value V1. It is possible to reduce the variation between devices in V2 and keep it within the specified range, and even if the target devices are different, it is possible to perform accurate current monitoring and current-based control, thereby increasing the performance and quality of the target devices to a high level. It is possible to maintain the

The current detection value input unit 46 of the current detection value conversion unit 30 in FIG. 9 detects the first output current detection voltage V1 by dividing, rectifying and smoothing the switch current flowing to the primary side of the target device. However, it is not limited to this and may be any device that detects the current of the target device. For example, the current detection value input section 46 may be a current detection value input unit 46 that uses a current detection resistor or the like to convert the current flowing through the target device into a voltage signal. It may also be a voltage conversion circuit.

[h. Modification of the present invention]
A modification of the switching power supply device according to the present invention will be described in more detail. The in-vehicle information display device of the present invention includes the following modifications in addition to the above-described embodiments.

(LLC resonant converter)
Although the switching power supply device of the above embodiment uses a half-bridge type LLC resonant converter as an example, it may also be a full-bridge type LLC resonant converter.

(Correction of V1-V2 conversion characteristics)
In the above embodiment, the set values of the pulse period and bias value corrected using a dedicated adjustment device are stored in the memory of the microprocessor that functions as the drive control section of the switching power supply, but the present invention is not limited to this. Instead, it may be set using a setting operation unit such as a dip switch.

(others)
Further, the present invention is not limited to the above-described embodiments, but includes appropriate modifications without impairing the objects and advantages thereof, and is not limited by the numerical values shown in the above-described embodiments.

10A, 10B: Switching power supply device 12a, 12b: Input terminal 14: Input rectifier smoothing circuit 15, 16: Switching element 18: Drive control section 20: Output transformer 22: Rectifier smoothing circuit 24a, 24b: Output terminal 25: Current balance terminal 26: Light shielding body 26: Load 28: Error detection section 30: Current detection value conversion section 32: Current balance circuit 34: Differential amplifier 36: Reference voltage source 38: Pulse width modulation section 40a: Photocoupler Light emitting element 40b: Photocoupler Light receiving elements 42, 62: Constant current source 44: Bias voltage source 46: Current detection value input section 48: Comparator 50: Triangular wave generator 52: RS-FF
54: Reset section 56: Reset pulse generation function 57: Pulse cycle setting section 58: Photocoupler 60: Current detection value output section 64: Bias section 66: Duty pulse generation function 68: Bias value setting section 70, 72, 74: V1 -V2 conversion characteristics

Claims (7)

A switching power supply equipped with a current balance circuit that aligns the output current value of each switching power supply to almost the same value based on the output current detection value based on the switch current flowing in the primary side when the outputs of multiple switching power supply are connected in parallel. A device,
A first detected output current value detected corresponding to the switch current flowing to the primary side is converted into a second detected output current value according to predetermined conversion characteristics based on a pulse width modulation section using pulse width modulation conversion. and a current detection value conversion unit that outputs the current detection value to the current balance circuit,
A switching power supply device characterized in that the conversion characteristic can be corrected by changing predetermined elements and maintaining the settings.
In the switching power supply device according to claim 1,
The conversion characteristic of the current detection value conversion section is a conversion characteristic of a predetermined linear function,
The predetermined element is an element for determining the pulse period of the pulse width modulation conversion and/or a bias value added to the first output current detection value input to the pulse width modulation section,
By changing and holding the setting of an element for determining the pulse period, the slope of the linear function is corrected, and by changing the bias value and holding the setting, the intercept of the linear function is corrected.
A switching power supply device characterized by:
In the switching power supply device according to claim 2,
The pulse width modulation section includes:
a current detection value input section that detects and inputs the first output current detection value by dividing, rectifying and smoothing the switch current flowing to the primary side;
a reset section that outputs a reset signal at a predetermined cycle;
a triangular wave generator that repeatedly generates a triangular wave signal at the period based on the reset signal;
a comparator that inputs and compares the first output current detection value and the triangular wave signal to perform pulse width modulation conversion and output a pulse width modulation signal;
The pulse width modulation signal is input to the set terminal, the reset signal is input to the reset terminal, and the inverted pulse width modulation signal is output from the inversion output terminal and is also supplied to the triangular wave generator to generate the triangular wave signal. A set-reset type flip-flop that generates the signal again after it stops generating.
a signal transmission section that electrically separates the inverted pulse width modulation signal outputted from the inversion output terminal by optical coupling of a photocoupler and transmits it to a secondary side;
a current detection value output unit that generates the second output current detection value by smoothing the inverted pulse width modulation signal transmitted by the signal transmission unit and outputs the second output current detection value to the current balance circuit;
Equipped with
The period of the reset signal outputted from the reset unit is changed and the setting is held, the slope of the linear function is corrected by changing the period of the pulse width modulation signal, and the first signal is input to the comparator. The intercept of the linear function is corrected by changing the bias value of the detected output current value and maintaining the setting.
A switching power supply device characterized by:
A current detection value conversion device that converts an inputted first output current detection value into a second output current detection value according to predetermined conversion characteristics based on a pulse width modulation section using pulse width modulation conversion, and outputs the second output current detection value. ,
A current detection value conversion device characterized in that the conversion characteristic can be corrected by changing a predetermined element and holding the setting.
In the current detection value conversion device according to claim 4,
The conversion characteristic is a conversion characteristic according to a predetermined linear function,
The predetermined element is an element for determining the pulse period of the pulse width modulation conversion and/or a bias value added to the first output current detection value input to the pulse width modulation section,
By changing and holding the setting of an element for determining the pulse period, the slope of the linear function is corrected, and by changing the bias value and holding the setting, the intercept of the linear function is corrected.
A current detection value conversion device characterized by:
In the current detection value conversion device according to claim 5,
The pulse width modulation section includes:
a current detection value input unit that detects and inputs the first output current detection value from a predetermined current flowing through a predetermined target device;
a reset section that outputs a reset signal at a predetermined cycle;
a triangular wave generator that repeatedly generates a triangular wave signal at the period based on the reset signal;
a comparator that inputs and compares the first output current detection value and the triangular wave signal to perform pulse width modulation conversion and output a pulse width modulation signal;
The pulse width modulation signal is input to the set terminal, the reset signal is input to the reset terminal, and the inverted pulse width modulation signal is output from the inversion output terminal and is also supplied to the triangular wave generator to generate the triangular wave signal. A set-reset type flip-flop that generates the signal again after it stops generating.
a current detection value output unit that generates and outputs the second output current detection value by smoothing the inverted pulse width modulation signal;
Equipped with
By changing the period of the reset signal outputted from the reset section and holding the setting, and changing the period of the pulse width modulation signal, the slope of the linear function is corrected, and the slope of the first order signal input to the comparator is The intercept of the linear function is corrected by changing the bias value of the detected output current value and maintaining the setting.
A current detection value conversion device characterized by:
In the current detection value conversion device according to claim 6,
The pulse width modulation section further electrically separates the inverted pulse width modulation signal output from the inversion output terminal of the flip-flop by optical coupling of a photocoupler, and transmits the electrically separated signal to the current detection value output section. What is claimed is: 1. A current detection value conversion device characterized by comprising a signal transmission section.

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