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MARS MV converter input plane design and implementation. Shuai Lu, Prof El-Sharkawi EE, University of Washington March 29, 2005. Outline. Input plane components overview MV switching circuit topology Converter startup power supply Switching operation and AB selection logic
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MARS MV converter input plane design and implementation Shuai Lu, Prof El-Sharkawi EE, University of Washington March 29, 2005
Outline • Input plane components overview • MV switching circuit topology • Converter startup power supply • Switching operation and AB selection logic • MV voltage and current measurement
Input plane components • Physically: • MV switching board, including MV switches, voltage dividers, (isolation diodes), charging resistors, etc. Mostly HV parts • MV logic board, including converter startup power supply, switching control logic circuit, and MV voltage sensing circuit. All LV parts.
Input plane components • Logically: • MV switching circuit • Converter startup power supply • Switching operation logic • AB selection logic • MV voltage sensing
MV switching circuit Diodes: isolate positive voltage from converter input S1_A and S1_B: 10kV isolation switches 3k ohm resistor: limits charging current when connecting converters to 10kV S2: bypass 10kV isolation switch
MV switching circuit • Rules behind switching operations: • Two converters, one in cold standby (means when one is working, another is isolated from 10kV) • When one converter has fault, it should be isolated so that the other one will work. • Switches not close to a load or open with current flowing at voltage higher than 500V (means S1 and S2 have to be latching switches, and operated at low voltage)
Converter startup power supply • Functions: • Supply power to logic circuit to operate switches • Supply power to converter gate signal for startup. Requires 20-25W, 10V for at least 4ms. • Must be available when converter is not running. Therefore after converter is shutdown for load fault, it can still be started. • The last two points mean that the startup power supply has to be periodical pulse. Otherwise, it’ll consume too much energy. (25W constantly) • Startup power supply has to be available both at low voltage for switching operations and high voltage for starting converter. • A 12V voltage regulator with input from 100V to 10kV, positive or negative.
Converter startup power supply Waveform at positive voltage (Sing_vin=0), switches are being opened: 1: VCC (inverted) 2: NAND gate output
Converter startup power supply Waveform at positive voltage (Sing_vin=0), switches are already opened: 1: VCC (inverted) 2: NAND gate output
Converter startup power supply Waveform at negative voltage (Sing_vin=1), when switches are being closed: 1: counter clock signal 2: fault detection circuit voltage sensing output (ignore the spikes, it can be seen as VCC inverted)
Switching operation logic • Functions: • Open all switches (S1 and S2) at positive voltage • Close S1 at negative voltage • Check fault at place (4), i.e., converter input. If fault exists, open S1.
Switching operation logic Switching operation logic circuit diagram
Switching operation logic Logic sequence for switching operations A_OK and B_OK are indicating the fault status of converter input. They are sent to node controller.
Switching operation logic Vin = -500V. When S1_A has 250k fault, S1_B has 500k fault. 1: clock signal 2: LPF(CA3140) output in fault detection circuit
Switching operation logic Vin = -500V. When S1_A has 250k fault, S1_B has no fault. 1: clock signal 2: LPF(CA3140) output in fault detection circuit
Switching operation logic Vin = -500V. When S1_A no fault, S1_B has no fault. 1: clock signal 2: LPF(CA3140) output in fault detection circuit
Switching operation logic Vin = -500V. When S1_A has 250k fault, S1_B has 500k fault. Whole process view. 1: clock signal 2: LPF(CA3140) output in fault detection circuit
AB selection logic • Functions: • Close S2 after Vin is higher than threshold voltage(5.3kV). • Close S3 to give converter gate signal to start it. • When converter A works, open S1_B to isolate B from 10kV. • When converter A doesn’t work, open S1_A and starts B.
AB selection logic AB selection logic circuit diagram
AB selection logic When converter is successfully started: 1: S3_A closing signal 2: VCC (inverted)
AB selection logic When converter is successfully started: 1: S3_A closing signal 2: S2 closing signal (inverted) 15ms earlier than S3_A closing signal
AB selection logic When converter is not successfully started: 1: S3_A closing signal 2: VCC (inverted) (the drop at the end is caused by the 3.6 ohm resistor simulating converter gate driving circuit)