RU84642U1 - CURRENT VOLTAGE CONVERTER - Google Patents

Abstract

The voltage-to-current converter, which contains a resistive bridge with a temperature sensor in one arm, is connected to the output of the power supply unit with a positive voltage on one diagonal of the bridge, the inputs of the differential operational amplifier with bipolar power supply and the anodes of two on-board reference diodes are connected to the other, their cathodes are connected to the resistor base of the pnp transistor of the knot for indicating a breakage of the temperature sensor, an LED is included in the collector circuit of this transistor, the emitter is connected to the input of the bias current adjuster and through the current-limiting a resistor - to the output of the power supply with a positive voltage, the output of the bias current adjuster is connected to the input of the stabilizer-regulator built into the operational amplifier, the resistive divider is connected to the battery, a bi-directional current switch is connected between the output of the operational amplifier and the input of the resistive divider, the output of the divider is connected to the input PWM comparator, the driver input is connected to the output of the PWM comparator, its output is connected to the control input of the inverter power key, the output of the generator through section diesel diodes are connected respectively to the power input of the inverter power key and the inputs of the battery and the bipolar power supply, the output of the inverter power key is connected to the excitation winding of the electric generator, characterized in that it also has a positive voltage limiter, and an analog CMOS as a bi-directional current switch - a demultiplexer, the inputs of the voltage limiter, the first address and second data input of the demultiplexer are connected to the output of the operational amplifier, to

Description

The utility model relates to electrical engineering and can be used in automated power supply systems for passenger cars with independent excitation generators.

Known for the closest to the technical essence voltage-to-current converter (see Charging voltage control device depending on temperature ЕВТ71. Electrical scheme 2471.071-974: 61/9 p. 1, Germany, 1992, Device for regulation and control of autonomous power supply system ДУУГ 28B. Technical description 2470.072 - 973: 61/9 p.4.5, Germany, 1993), which contains a resistive bridge with a temperature sensor in one arm, a positive voltage supply output connected to one diagonal of the bridge, and inputs to the other differential op a bipolar powered amplifier and the anodes of two counterclockwise connected diodes, their cathodes are connected to a resistor of the base of the transistor of the thermistor breakage indicating unit, a LED is connected to the collector circuit of this transistor, the emitter is connected to the input of the bias current adjuster and, through current limiting resistors, to the base of the transistor bi-directional current switch and the output of the power supply with a positive voltage, the output of the bias current master is connected to the input of the built-in operational amplifier l stabilizer - regulator, the output of the operational amplifier is connected to the anode of the cut-off diode, its cathode is connected to the emitter of the transistor current switch, the resistive divider is connected to the battery, the collector of the transistor current switch is connected to the input of this divider, the output of the divider is connected to the input of the PWM comparator, output The PWM comparator through the driver is connected to the control input of the inverter power key, the output of the electric generator through the diodes is connected respectively to the power input of the inverter Operations and the battery input and a bipolar power supply, an inverter connected to the output of the generator excitation winding, the power input of the PWM comparator and drivers are connected to the output of the power supply with the positive voltage.

The disadvantages of this converter are:

1. Unlimited reduction of the installation voltage with increasing temperature in the area of the battery. This can lead to the shutdown of some electric consumers of the car (for example, such as air conditioning, fan) and to a decrease in services for passengers.

2. Low accuracy of switching signals by a diode-transistor bi-directional current switch due to the nonlinearity of the working area of its output current-voltage characteristics.

3. Low reliability of the known current switch. Since the operation of its transistor switch depends on the output voltage of the differential operational amplifier and the state of the temperature sensor break indication unit, when certain failures of this node are detected, the key transistor will be blocked, and when the temperature sensor is connected and operating correctly, the system will false transfer the system to the mode of limiting the installation voltage at a given level. In addition, some malfunctions of the display unit lead to a change in the voltage regulation parameters. Moreover, when this happens, it is impossible to unambiguously determine the "weak" place, which complicates the operation. The utility model is based on the task:

- to ensure that the voltage of the installation is limited to a level slightly higher than that required to turn on energy-intensive consumers and stabilize it in the range of positive operating temperatures;

- to increase reliability, for this it is necessary to minimize the influence of the auxiliary technological unit for indicating a breakage of the temperature sensor on a bi-directional current switch, i.e. the main work of the voltage regulator;

- use an analog switch on field-effect transistors with a high input DC resistance, linearity of characteristics, and the possibility of opening the output by a special command as a bi-directional current commutator.

The problem is solved in that the voltage-to-current converter contains a resistive bridge with a temperature sensor in one arm, a positive voltage output of the power supply unit is connected to one diagonal of the bridge, the inputs of the differential operational amplifier with bipolar power supply and the anodes of the two on-board bind diodes, their the cathodes are connected to the resistor of the base of the transistor of the transistor of the temperature sensor breakage indication node, a LED is included in the collector circuit of this transistor, the emitter is connected to the input of the current setter and through a current-limiting resistor - to the output of the power supply with a positive voltage, the output of the bias current regulator is connected to the input of the stabilizer-regulator integrated in the operational amplifier, the resistive divider is connected to the battery, a bi-directional current switch is connected between the output of the operational amplifier and the input of the resistive divider, output the divider is connected to the input of the PWM comparator, the driver input is connected to the output of the PWM comparator, its output is to the control input of the inverter power key, the output the generator through the diodes is connected respectively to the power supply input of the inverter power switch and the inputs of the battery and the bipolar power supply, the output of the inverter power switch is connected to the excitation coil of the generator, in accordance with the utility model, a positive voltage limiter is additionally introduced into it, and as a bi-directional current switch - analog complementary, metal oxide-semiconductor (CMOS) demultiplexer, voltage limiter inputs, first address the first and second data input of the demultiplexer are connected to the output of the operational amplifier, a load resistor is connected to the first data input, the output of the demultiplexer is connected to the input of the resistive divider, the second address input of the demultiplexer is connected to the "common" bus, the resolution input of the output data of the demultiplexer is connected to the temperature sensor.

The essence of the utility model is illustrated by drawings, in which Fig. 1 is a structural block diagram of the proposed voltage-to-current converter, and Fig. 2 is a characteristic of controlling the voltage of the installation depending on temperature (high-quality).

The proposed voltage-to-current converter 1 consists of a resistive bridge 2 (R1..R4 with a temperature sensor R2 and binding diodes VD1, VD2), a differential operational amplifier 3 with bipolar power supply, a base resistor 4, a transistor indicating the breakage of the temperature sensor 5, and a bias current adjuster 6 , positive voltage limiter 7, analog CMOS demultiplexer 8 with decoder 9, load resistor 10, resistive divider 11, PWM comparator 12, driver 13, inverter power key 14, field winding 15 of the generator 16, a mutator battery 17, isolation diodes 18, 19, a bipolar power supply 20.

The voltage-to-current converter 1 with a connected and serviceable temperature sensor R2 works as follows.

When you turn on the power supply system of the car from the battery 17, the power supply unit 20 and the resistive bridge 2 and the entire logic 3, 5, 6, 8, 12, 13 of the voltage-to-current converter 1 are fed from it. Positive voltage reference from the common connection point of the resistors R3, R4 resistive bridge 2 is fed to the inverting input of the differential operational amplifier 3 with bipolar power. The non-inverting input of this amplifier and the input of the resolution E of the demultiplexer 8 are supplied with a temperature-dependent voltage drop from the bridge temperature sensor R2. Its value corresponds to a low level for the CMOS structure. The amplified difference of the two input voltages controls the operation of the analog CMOS demultiplexer 8 through the built-in decoder 9. As a temperature sensor R2, a resistance thermoconverter with a copper sensitive element (TCM) is used. Using the bias current adjuster 6, the operating mode of the stabilizer-regulator integrated in the differential amplifier 3 is set, which determines the output parameters of the amplifier.

Adjustment provide a zero value of the output voltage of the differential amplifier 3 at a certain initial temperature value. By changing the gain of the operational amplifier 3, the required temperature sensitivity [mV / k] of the output voltage is obtained, the value of which corresponds to the values of the CMOS logic levels of the demultiplexer taking into account its supply voltage.

As soon as at a positive ambient temperature near the battery 17, the voltage at the non-inverting input of the differential amplifier 3 exceeds the reference voltage at its inverting input, then the output voltage of the amplifier will be high. Obviously, at low temperatures, the output voltage of the operational amplifier will be low. The operation of the demultiplexer is carried out in accordance with the table.

Inputs Data Channel Enabled Output resolution Address E A1 A2 N (low level) N N D1 N AT N D2 In (high level) x x Z state

With an active level E (low voltage is present), the signal that is present at the selectable input is transmitted to the output from demultiplexer 8. If a high level voltage is applied to input E, then regardless of the state of the address inputs A1, A2, the output of the demultiplexer will open, go into a high-impedance Z-state.

It follows from the table that, with the connection indicated in FIG. 1, the decoder 9 of the demultiplexer 8 allows, with a high signal level at the address input Al and low at the inputs A2 and E, to transmit data from the output of the differential amplifier 3 through channel D2 to the input of the resistive divider 11 and at low level at the inputs A1, A2 and E, close the input of the resistive divider 11 through the channel D1 to the load resistor 10. The operating voltage of the battery 17, scaled by the resistive divider 11, is summed with the offset from the demultiplexer 8. The total signal with compares with the setpoint voltage at the input of the PWM comparator 12, amplifies and compares with the sawtooth voltage of the modulator, resulting in the formation of rectangular pulses of varying duration, which through the driver 13 control the power switch of the inverter 14. Moreover, as the signal level at the input of the PWM comparator 12 approaches to the voltage level of the setting, the duration of the pulses at the output of the modulator varies from the maximum working to zero. The pulses on the field winding 15 determine the value of the output voltage of the generator 16: with an increase in the pulse duration, the generator voltage increases and vice versa. Under conditions of elevated temperatures in the area where the battery 17 is located, the greater the positive voltage level from the output of the operational amplifier 3 and, consequently, the greater the outgoing current from the converter 1 towards the resistive divider 11, the greater the signal level at the input of the PWM comparator and the shorter the duration excitation pulses and the magnitude of the generator voltage. In order to prevent operation of reducing the installation voltage outside the acceptable values at the output of the operational amplifier 3, a positive voltage limiter 7 is connected. At negative operating temperatures and a correspondingly low voltage level at the output of the operational amplifier 3, the current flowing into the converter 1 from the resistive divider 11 through the channel D1 of the demultiplexer 8 and a load resistor 10 reduces the voltage at the input of the PWM comparator, expanding the duration of the excitation pulses to the maximum a working value, to increase the generator voltage. In general, when the generator is operating, its output voltage is regulated depending on the temperature at the location of the battery 17 by changing the pulse duration in the field winding 15. A qualitative characteristic of the voltage regulation of the installation depending on the temperature is shown in FIG. 2.

Separating diode 18 eliminates the power supply to the inverter 14 during main operation directly from the battery 17 and its possible discharge through the stator winding of the generator 16. Diode 19 is necessary to provide diagnostic control of the inverter when the generator 16 is idle.

In normal operation, the voltage drop across the base 4 resistor from the current from the output diagonal of resistive bridge 2 (through the coupling diodes VD1, VD2) is less than the voltage on the emitter, while the pnp transistor of node 5 is open and the LED connected to the collector circuit will glow, which indicates the health of the R2 temperature sensor and the integrity of its communication lines with the converter. In the event of a breakdown of the temperature sensor R2 or its communication lines with the converter, the voltage at the input E of the demultiplexer 8 and at the base resistor 4 will be approximately equal to the positive voltage from the output of the power supply unit 20, i.e. correspond to a high level. In this case

- the output of the demultiplexer 8 is disconnected from the input of the resistive divider 11 and the system goes into voltage limiting mode at a level corresponding to the main adjusted value;

- the pnp transistor of node 5 is locked at the base-emitter junction, the LED "break of the temperature sensor" ceases to glow, which signals a marriage situation.

Thus, the control characteristic implemented in accordance with FIG. 2 with a two-sided limitation of the installation voltage eliminates both recharging the battery at negative temperatures and turning off consumers at maximum positive ambient temperatures in the battery placement zone, thereby preserving the planned list of services for passengers the wagon.

Due to the large input resistance of the CMOS structure, the output of the resolution of the demultiplexer E is connected directly to the temperature sensor, which reduces the likelihood of a false transfer of the system to the voltage limiting mode at a level corresponding to the main adjusted value. In addition to higher reliability, the integrated demultiplexer provides stability of parameters under the influence of destabilizing factors, simplifies adjustment operations, and reduces power consumption.

The advantage of the analog CMOS demultiplexer is the ability to transmit signals with high accuracy, since such a switch has a linear range of output current-voltage characteristics, it does not have zero residual voltage and is capable of transmitting signals with various amplitudes and any polarity without distortion.

The operation of the analog CMOS demultiplexer practically does not depend on the state of the display node of the breakage of the temperature sensor and in case of a defect in the latter, the failed element is easily determined by indirect signs. In this case, the main mode is not violated - the voltage regulation of the installation.

Claims (1)

The voltage-to-current converter, which contains a resistive bridge with a temperature sensor in one arm, is connected to the output of the power supply unit with a positive voltage on one diagonal of the bridge, the inputs of the differential operational amplifier with bipolar power supply and the anodes of two on-board reference diodes are connected to the other, their cathodes are connected to the resistor base of the pnp transistor of the knot for indicating a breakage of the temperature sensor, an LED is included in the collector circuit of this transistor, the emitter is connected to the input of the bias current adjuster and through the current-limiting a resistor - to the output of the power supply with a positive voltage, the output of the bias current adjuster is connected to the input of the stabilizer-regulator built into the operational amplifier, the resistive divider is connected to the battery, a bi-directional current switch is connected between the output of the operational amplifier and the input of the resistive divider, the output of the divider is connected to the input PWM comparator, the driver input is connected to the output of the PWM comparator, its output is connected to the control input of the inverter power key, the output of the generator through section diesel diodes are connected respectively to the power input of the inverter power key and the inputs of the battery and the bipolar power supply, the output of the inverter power key is connected to the excitation winding of the electric generator, characterized in that it also has a positive voltage limiter, and an analog CMOS as a bi-directional current switch - a demultiplexer, the inputs of the voltage limiter, the first address and second data input of the demultiplexer are connected to the output of the operational amplifier, to A load resistor is connected to the first data input, the output of the demultiplexer is connected to the input of the resistive divider, the second address input of the demultiplexer is connected to the "common" bus, and the resolution input to the output data of the demultiplexer is connected to the temperature sensor.