Modular high voltage power supply for chemical analysis
View Patent ↗A high voltage power supply for use in a system such as a microfluidics system, uses a DC—DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC—DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.
1. A module configured for plug in electrical connection to a device having a processor, said module comprising:
a high voltage power supply including a DC—DC converter, a voltage controlled resistor and a feedback circuit, said DC—DC converter having a low voltage input to which an input current is applied and a high voltage output at which an output current and an output voltage are developed, said voltage controlled resistor being electrically coupled to said high voltage output in parallel with said DC—DC converter and having an input wherein a resistance of said voltage controlled resistor is determined by an input voltage applied to said input of said voltage controlled resistor, said feedback circuit being operatively connected between said high voltage output of said DC—DC converter and said input of said voltage controlled resistor and developing said input voltage as a function of a reference voltage and said output voltage and further applying said input voltage to said input of said voltage controlled resistor such that a variation of said input voltage in response to a variation of said output voltage causes a variation of said resistance in opposition to said variation of said output voltage to maintain said output voltage constant;
a memory in which information relating to voltage conversion curves of said DC—DC converter is stored and readable by said processor when said module is connected to said device;
an operation detection unit that develops a voltage proportional to said output voltage; and
a current sensor that develops a voltage proportional to said output current;
said microprocessor being operative when said module is connected to said device to develop said reference voltage in response to each of said voltage developed by said operation detection unit and said voltage developed by said current sensor in accordance with said information to maintain said output current constant.
2. A module as set forth in claim 1 further comprising a voltage divider in parallel with said voltage controlled resistor, said voltage divider developing a feedback signal as a function of said out put voltage, said feed back signal being applied to each of said feedback circuit, said feedback circuit developing said input voltage as a function of said feedback signal.
3. A module as set forth in claim 2 wherein said feedback circuit compares said feedback signal to said reference voltage to develop said input voltage.
4. A module as set forth in claim 3 wherein said feedback circuit is an operational amplifier that determines an error between said reference voltage and said feedback signal.
5. A module as set both in claim 2 wherein said feedback signal is applied to said operation detection unit, said operation detection unit developing said voltage proportional to said output voltage in response to said feedback signal.
6. A module as set forth in claim 1 wherein said voltage controlled resistor is an MOS photo relay having a photo diode to which said input voltage is applied, and a pair of series connected MOS switches defining said resistor, said photodiode emitting light in response to said input voltage such that an increase in said input voltage causes said light to decrease and a decrease in said input voltage causes said light to increase, said switches developing a current proportionally in response to said light wherein said current in said switches determines said resistance of said voltage controlled resistor.
7. A module as set forth in claim 1 further comprising a voltage follower transistor electrically coupled between said feedback circuit and said low voltage input of said DC—DC converter, said input voltage developed by said feedback circuit being applied to said voltage follower transistor, said volume follower transistor developing said input current applied to said low voltage input in response to input voltage such that input voltage causes said input current to decrease in response to an in said output voltage and said input voltage causes said input current to increase in response to a decrease in said output voltage.